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  • 1.
    Abdel-Magied, Ahmed F.
    et al.
    KTH Royal Inst Technol, Dept Chem Engn, S-100 44 Stockholm, Sweden.;Nucl Mat Author, POB 530,El Maadi, Cairo, Egypt..
    Ashour, Radwa M.
    KTH Royal Inst Technol, Dept Chem Engn, S-100 44 Stockholm, Sweden.;Nucl Mat Author, POB 530,El Maadi, Cairo, Egypt..
    Fu, Le
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Hunan, Peoples R China..
    Dowaidar, Moataz
    King Fahd Univ Petr & Minerals KFUPM, Dept Bioengn, Dhahran 31261, Saudi Arabia..
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Forsberg, Kerstin
    KTH Royal Inst Technol, Dept Chem Engn, S-100 44 Stockholm, Sweden..
    Abdelhamid, Hani Nasser
    Assiut Univ, Dept Chem, Adv Multifunct Mat Lab, Assiut 71515, Egypt.;Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Magnetic metal-organic frameworks for efficient removal of cadmium(II), and lead(II) from aqueous solution2022In: Journal of Environmental Chemical Engineering, E-ISSN 2213-3437, Vol. 10, no 3, article id 107467Article in journal (Refereed)
    Abstract [en]

    Efficient and convenient methods for the removal of toxic heavy metal ions especially Cd(II) and Pb(II) from aqueous solutions is of great importance due to their serious threat to public health and the ecological system. In this study, two magnetic metal-organic frameworks (namely: Fe3O4@ZIF-8, and Fe3O4@UiO-66-NH2) were synthesized, fully characterized, and applied for the adsorption of Cd(II) and Pb(II) from aqueous solutions. The adsorption efficiencies for the prepared nanocomposites are strongly dependent on the pH of the aqueous solution. The maximum adsorption capacities of Fe3O4@UiO-66-NH2, and Fe3O4@ZIF-8 at pH 6.0 were calculated to be 714.3 mg.g(-), and 370 mg.g(-1) for Cd(II), respectively, and 833.3 mg.g(-1), and 666.7 mg.g(-1) for Pb(II), respectively. The adsorption process follows a pseudo-second-order model and fit the Langmuir isotherm model. Moreover, the thermodynamic studies revealed that the adsorption process is endothermic, and spontaneous in nature. A plausible adsorption mechanism was discussed in detail. The magnetic adsorbents: Fe3O4@ZIF-8, and Fe3O4@UiO-66-NH2 showed excellent reusability, maintaining the same efficiency for at least four consecutive cycles. These results reveal the potential use of magnetic Fe3O4@ZIF-8, and Fe3O4@UiO-66-NH2 as efficient adsorbents in removing Cd(II) and Pb(II) from aqueous solutions.

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  • 2.
    Abenayake, Himesha
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Additively Manufactured Rare Earth Free Permanent Magnets2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It’s well known that MnAl(C) material consists of a metastable phase (τ) with promising ferromagnetic properties, produced either by controlled cooling from the high-temperature hexagonal ε-phase or rapid cooling that freezes the ε-phase followed by low-temperature annealing. Due to the high cooling rates involved, additive manufacturing (AM) especially selective laser melting (SLM), has been identified as a possible method to retain the high-temperature ε-phase, hence containing a potential capacity to produce permanent magnets upon low-temperature annealing. Moreover, the competency of additive manufacturing to address manufacturing design complexity, material scarcity and tailored properties, yields a great opportunity to produce permanent magnets with suitable magnetic properties for complex applications. This work provides a systematic study on three main aspects; development of printing parameters for improved relative density of as-printed MnAl(C) samples; investigation of the influence of scanning strategies on the crystallographic texture of as-printed and annealed samples; investigation of the influence of annealing time and temperature on τ-phase purity and magnetic properties. It was found that laser remelting (multiple laser exposure) combined with specific scanning strategies is a promising path to enhance the relative density of as-printed samples. Some specific scanning strategies were found to be capable of retaining relatively strong crystallographic textured ε-phase in as-printed samples. Following the annealing process for ε→τ transformation, only a partial transformation of crystallographic texture was observed. Characterization of annealed samples through XRD (x-ray diffraction) and phase fractions calculations through Rietveld refinement reveals that relatively short annealing times and low temperatures result in incomplete ε→τ transformation. In addition, longer annealing times and higher temperatures surpass the complete ε→τ transformation and lead to the formation of equilibrium phases subsequently reducing the magnetic performance. Furthermore, the experimental findings demonstrated a pronounced influence of higher carbon content in the powder, resulting in improved magnetic properties.

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    Additively Manufactured Rare Earth Free Permanent Magnets
  • 3.
    Ali, Hasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Uppsala Univ, Dept Engn Sci, Appl Mat Sci, Electron Microscopy & Nanoengn, Box 534, S-75121 Uppsala, Sweden..
    Negi, Devendra Singh
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden.;Max Planck Inst Solid State Res, Stuttgart Ctr Electron Microscopy, Heisenbergstr 1, D-70569 Stuttgart, Germany..
    Warnatz, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Uppsala Univ, Dept Engn Sci, Appl Mat Sci, Electron Microscopy & Nanoengn, Box 534, S-75121 Uppsala, Sweden..
    Atomic resolution energy-loss magnetic chiral dichroism measurements enabled by patterned apertures2020In: Physical Review Research, E-ISSN 2643-1564, Vol. 2, no 2, article id 023330Article in journal (Refereed)
    Abstract [en]

    Electron energy-loss magnetic chiral dichroism (EMCD) has the potential to measure magnetic properties of the materials at atomic resolution but the complex distribution of magnetic signals in the zone axis and the overlapping diffraction discs at higher beam convergence angles make the EMCD signal acquisition challenging. Recently, the use of ventilator apertures to acquire the EMCD signals with atomic resolution was proposed. Here we give the experimental demonstration of several types of ventilator apertures and obtain a clear EMCD signal at beam semiconvergence angles of 5 mrad. To simplify the experimental procedures, we propose a modified ventilator aperture which not only simplifies the complex scattering conditions but reduces the influence of lens aberrations on the EMCD signal as compared to the originally proposed ventilator apertures. In addition, this modified aperture can be used to analyze magnetic crystals with various symmetries and we demonstrate this feature by acquiring EMCD signals on different zone axis orientations of an Fe crystal. With the same aperture we obtain EMCD signals with convergence angles corresponding to atomic resolution electron probes. After the theoretical demonstration of the EMCD signal on a zone axis orientation at high beam convergence angles, this work thus overcomes the experimental and methodological hurdles and enables atomic resolution EMCD on the zone axis by using apertures.

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  • 4.
    Ali, Hasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Forschungszentrum Julich, Ernst Ruska Ctr Microscopy & Spect Electrons, D-52425 Julich, Germany..
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Buergler, Daniel E.
    Forschungszentrum Julich, Peter Grunberg Inst, D-52425 Julich, Germany..
    Adam, Roman
    Forschungszentrum Julich, Peter Grunberg Inst, D-52425 Julich, Germany..
    Schneider, Claus M.
    Forschungszentrum Julich, Peter Grunberg Inst, D-52425 Julich, Germany..
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Thersleff, Thomas
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Noise-dependent bias in quantitative STEM-EMCD experiments revealed by bootstrapping2024In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 257, article id 113891Article in journal (Refereed)
    Abstract [en]

    Electron magnetic circular dichroism (EMCD) is a powerful technique for estimating element-specific magnetic moments of materials on nanoscale with the potential to reach atomic resolution in transmission electron microscopes. However, the fundamentally weak EMCD signal strength complicates quantification of magnetic moments, as this requires very high precision, especially in the denominator of the sum rules. Here, we employ a statistical resampling technique known as bootstrapping to an experimental EMCD dataset to produce an empirical estimate of the noise-dependent error distribution resulting from application of EMCD sum rules to bcc iron in a 3-beam orientation. We observe clear experimental evidence that noisy EMCD signals preferentially bias the estimation of magnetic moments, further supporting this with error distributions produced by Monte-Carlo simulations. Finally, we propose guidelines for the recognition and minimization of this bias in the estimation of magnetic moments.

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  • 5.
    Ali, Hasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Mirpur Univ Sci & Technol MUST, Dept Elect Engn, Mirpur 10250, Ajk, Pakistan.;Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden. .
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Warnatz, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Simultaneous mapping of EMCD signals and crystal orientations in a transmission electron microscope2021In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, article id 2180Article in journal (Refereed)
    Abstract [en]

    When magnetic properties are analysed in a transmission electron microscope using the technique of electron magnetic circular dichroism (EMCD), one of the critical parameters is the sample orientation. Since small orientation changes can have a strong impact on the measurement of the EMCD signal and such measurements need two separate measurements of conjugate EELS spectra, it is experimentally non-trivial to measure the EMCD signal as a function of sample orientation. Here, we have developed a methodology to simultaneously map the quantitative EMCD signals and the local orientation of the crystal. We analyse, both experimentally and by simulations, how the measured magnetic signals evolve with a change in the crystal tilt. Based on this analysis, we establish an accurate relationship between the crystal orientations and the EMCD signals. Our results demonstrate that a small variation in crystal tilt can significantly alter the strength of the EMCD signal. From an optimisation of the crystal orientation, we obtain quantitative EMCD measurements.

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  • 6.
    Ali, Hasan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Forschungszentrum Julich, Ernst Ruska Ctr Microscopy & Spect Electrons & Pe, D-52425 Julich, Germany..
    Sathyanath, Sharath Kumar Manjeshwar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Uusimaki, Toni
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Thersleff, Thomas
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Single scan STEM-EMCD in 3-beam orientation using a quadruple aperture2023In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 251, article id 113760Article in journal (Refereed)
    Abstract [en]

    The need to acquire multiple angle-resolved electron energy loss spectra (EELS) is one of the several critical challenges associated with electron magnetic circular dichroism (EMCD) experiments. If the experiments are performed by scanning a nanometer to atomic-sized electron probe on a specific region of a sample, the precision of the local magnetic information extracted from such data highly depends on the accuracy of the spatial registration between multiple scans. For an EMCD experiment in a 3-beam orientation, this means that the same specimen area must be scanned four times while keeping all the experimental conditions same. This is a non-trivial task as there is a high chance of morphological and chemical modification as well as non-systematic local orientation variations of the crystal between the different scans due to beam damage, contamination and spatial drift. In this work, we employ a custom-made quadruple aperture to acquire the four EELS spectra needed for the EMCD analysis in a single electron beam scan, thus removing the above-mentioned complexities. We demonstrate a quantitative EMCD result for a beam convergence angle corresponding to sub-nm probe size and compare the EMCD results for different detector geometries.

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  • 7.
    Andersen, Ole Zoffmann
    et al.
    Univ Bern, Dept Periodontol, Frieburg str 7, CH-3010 Bern, Switzerland.;Inst Straumann AG, Basel, Switzerland..
    Bellon, Benjamin
    Inst Straumann AG, Basel, Switzerland.;Univ Tampere, Fac Med & Hlth Technol, Tampere, Finland..
    Lamkaouchi, Maryam
    Univ Bordeaux, INSERM BIOTIS, U1026, Bordeaux, France..
    Brunelli, Marzia
    Inst Straumann AG, Basel, Switzerland..
    Wei, Qiuju
    Univ Bern, Dept Periodontol, Frieburg str 7, CH-3010 Bern, Switzerland..
    Procter, Philip
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Pippenger, Benjamin E.
    Univ Bern, Dept Periodontol, Frieburg str 7, CH-3010 Bern, Switzerland.;Inst Straumann AG, Basel, Switzerland..
    Determining primary stability for adhesively stabilized dental implants2023In: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, Vol. 27, p. 3741-3748Article in journal (Refereed)
    Abstract [en]

    Objectives: To examine factors influencing the primary stability of dental implants when stabilized in over-sized osteotomies using a calcium phosphate-based adhesive cement was the objective.

    Methods: Using implant removal torque measurements as a surrogate for primary stability, we examined the influence of implant design features (diameter, surface area, and thread design), along with cement gap size and curing time, on the resulting primary implant stability.

    Results: Removal torque values scaled with implant surface area and increasing implant diameters. Cement gap size did not alter the median removal torque values; however, larger gaps were associated with an increased spread of the measured values. Among the removal torque values measured, all were found to be above 32 Ncm which is an insertion torque threshold value commonly recommended for immediate loading protocols.

    Conclusion: The adhesive cement show potential for offering primary implant stability for different dental implant designs. In this study, the primary parameters influencing the measured removal torque values were the implant surface area and diameter. As the liquid cement prevents the use of insertion torque, considering the relationship between insertion and removal torque, removal torque can be considered a reliable surrogate for primary implant stability for bench and pre-clinical settings.

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  • 8.
    Ansari, Shaquib Rahman
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Suárez-López, Yael del Carmen
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Thersleff, Thomas
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Katsaros, Ioannis
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Åhlén, Michelle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    Karlgren, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Rinaldi-Ramos, Carlos
    Teleki, Alexandra
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    A pharmaceutical quality by design approach to develop high-performance nanoparticles for magnetic hyperthermiaManuscript (preprint) (Other academic)
  • 9. Antonio Cabas, Vidani
    et al.
    Léo, Choubrac
    Jose, Marquez-Prieto
    Thomas, Unold
    Matthias, Maiberg
    Roland, Scheer
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Shandong Univ, Sch Microelect, Jinan 250100, Peoples R China.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Robin, Pauer
    Evgeniia, Gilshtein
    A. N., Tiwari
    Yaroslav, Romanyuk
    Influence of the Rear Interface on Composition and Photoluminescence Yield of CZTSSe Absorbers: A Case for an Al2O3 Intermediate Layer2021In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 13, no 16, p. 19487-19496Article in journal (Refereed)
    Abstract [en]

    The rear interface of kesterite absorbers with Mo back contact represents one of the possible sources of nonradiative voltage losses (Delta V-oc,V-nrad) because of the reported decomposition reactions, an uncontrolled growth of MoSe2, or a nonoptimal electrical contact with high recombination. Several intermediate layers (IL), such as MoO3, TiN, and ZnO, have been tested to mitigate these issues, and efficiency improvements have been reported. However, the introduction of IL also triggers other effects such as changes in alkali diffusion, altered morphology, and modifications in the absorber composition, all factors that can also influence Delta V-oc,V-nrad. In this study, the different effects are decoupled by designing a special sample that directly compares four rear structures (SLG, SLG/Mo, SLG/Al2O3, and SLG/Mo/Al2O3) with a Na-doped kesterite absorber optimized for a device efficiency >10%. The IL of choice is Al2O3 because of its reported beneficial effect to reduce the surface recombination velocity at the rear interface of solar cell absorbers. Identical annealing conditions and alkali distribution in the kesterite absorber are preserved, as measured by time-of-flight secondary ion mass spectrometry and energy-dispersive X-ray spectroscopy. The lowest Delta V-oc,V-nrad of 290 mV is measured for kesterite grown on Mo, whereas the kesterite absorber on Al2O3 exhibits higher nonradiative losses up to 350 mV. The anticipated field-effect passivation from Al2O3 at the rear interface could not be observed for the kesterite absorbers prepared by the two-step process, further confirmed by an additional experiment with air annealing. Our results suggest that Mo with an in situ formed MoSe2 remains a suitable back contact for high-efficiency kesterite devices.

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  • 10.
    Atif, Abdul Raouf
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Carter, Sarah-Sophia
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Deng, Hanlu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Tenje, Maria
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Mestres, Gemma
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    A Universal Microfluidic Platform for In Vitro Biomaterial Evaluation2022Conference paper (Other academic)
    Abstract [en]

    INTRODUCTION: Conventionally, the biological properties of biomaterials are evaluated using well plates. Although being a standardized method, it is static in terms of fluid flow and is far from the physiological conditions found in vivo. This work presents a versatile microfluidic system that allows for integration of different biomaterials (ceramic, metals and polymers) under dynamic conditions.

    METHODS: The Universal Biomaterial-on-Chip (UBOC) consisted of two separate 3D printed (Polylactic acid, Ultimaker 2+) structures: the upper layer which contains the channel through which medium can flow (Fig1A) and the bottom layer that holds and secures the biomaterial in place (Fig 1B). A glass coverslip was taped to the upper layer to tightly seal the channel. Subsequently, an oval Polydimethylsiloxane (PDMS) gasket (l=10mm,w=7mm, h=0.8mm) was inserted into the periphery of the channel in the upper layer. Furthermore, magnets (Ø=12mm, h=3mm) were glued on both sides of the bottom layer. To close the channel, two magnets were placed on the upper layer, causing attraction to the magnets in the bottom layer. The gasket would then directly interface with the biomaterial inside the bottom layer, creating a leak-free channel on its surface. MC3T3-E1 pre-osteoblasts were seeded in the UBOC platform (50,000 cells/cm2) on calcium-deficient hydroxyapatite (HA) (Ø=15mm) and clinical grade titanium (Ti) (Ø=12mm). The cells were cultured for a period of 5 days at a flow rate of 2 μl/min using supplemented MEM-α medium (Hyclone, 10% FBS, 1% Pen-Strep). On day 5, the cells were stained on-chip with Live/Dead stain (Calcein, Propidium Iodide and Hoechst) and subsequently imaged.

    RESULTS: HA and Ti samples were successfully integrated into the UBOC. Cells cultured on-chip displayed a high degree of viability and confluence on day 5 of culture on both HA and Ti substrates (Fig 2).

    DISCUSSION & CONCLUSIONS: UBOC presents the possibility for flexible in vitro biomaterial analysis as it allows for easy incorporation of flow to conventional cell culture regimes in a low-cost manner. Via this method,cells can be cultured on the biomaterial with exposure to fluid flow and controlled shear-stress. The platform is compatible with standard characterization methods, such as imaging and biochemical cell analysis. In addition, since the system is designed to be opened and closed, the biomaterial could be easily accessed, harvested and transferred to a regular tissue culture vessel,enabling standard off-chip biochemical assays and protocols to be performed for further analysis.

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  • 11.
    Atif, Abdul Raouf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Pujari-Palmer, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Tenje, Maria
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology.
    Mestres, Gemma
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology.
    A microfluidics-based method for culturing osteoblasts on biomimetic hydroxyapatite2021In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 127, p. 327-337Article in journal (Refereed)
    Abstract [en]

    The reliability of conventional cell culture studies to evaluate biomaterials is often questioned, as in vitro outcomes may contradict results obtained through in vivo assays. Microfluidics technology has the potential to reproduce complex physiological conditions by allowing for fine control of microscale features such as cell confinement and flow rate. Having a continuous flow during cell culture is especially advantageous for bioactive biomaterials such as calcium-deficient hydroxyapatite (HA), which may otherwise alter medium composition and jeopardize cell viability, potentially producing false negative results in vitro. In this work, HA was integrated into a microfluidics-based platform (HA-on-chip) and the effect of varied flow rates (2, 8 and 14 µl/min, corresponding to 0.002, 0.008 and 0.014 dyn/cm2, respectively) was evaluated. A HA sample placed in a well plate (HA-static) was included as a control. While substantial calcium depletion and phosphate release occurred in static conditions, the concentration of ions in HA-on-chip samples remained similar to those of fresh medium, particularly at higher flow rates. Pre-osteoblast-like cells (MC3T3-E1) exhibited a significantly higher degree of proliferation on HA-on-chip (8 μl/min flow rate) as compared to HA-static. However, cell differentiation, analysed by alkaline phosphatase (ALP) activity, showed low values in both conditions. This study indicates that cells respond differently when cultured on HA under flow compared to static conditions, which indicates the need for more physiologically relevant methods to increase the predictive value of in vitro studies used to evaluate biomaterials.

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    Supplementary section
  • 12.
    Atif, Abdul Raouf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology.
    Pujari-Palmer, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Tenje, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology.
    Influence of flow in the adhesion and proliferation of cells on hydroxyapatite integrated in a microscale culture2021Conference paper (Other academic)
    Abstract [en]

    INTRODUCTION:

    Synthetic biomaterials, such as calcium phosphate cements (CPCs), are a promising alternative to autologous bone to enhance bone regeneration. Calcium-deficient hydroxyapatite (CDHA), the end-product of apatite cements, matches the inorganic phase of the bone and exhibits excellent biocompatibility in vivo [1]. However,  in vitro, CDHA uptakes calcium ions (Ca2+) from cell culture medium [2], causing detrimental effects on cell activity and function [3]. The aim of this work was to integrate CDHA into a microfluidic chip that provides continued culture medium supply, and to evaluate cell adhesion and proliferation as compared to standard well plates.

    METHODS:

    CDHA was integrated in a polydimethylsiloxane (PDMS)-glass microfluidic chip (CDHA-on-chip). PDMS was cured in a 3D-printed mould at 60°C for 2h. α-tricalcium phosphate was mixed with 2.5% w/v Na2HPO4(aq) (liquid-to-powder of 0.65 ml/g) and the CPC was cast within a PDMS pocket. The CPC was immersed in an aqueous solution at 37°C for 10 days to ensure full transformation to CDHA. Through plasma treatment, a glass slide was bonded to the PDMS holding the CDHA, thus forming a 0.5mm channel above the CDHA. CDHA samples were pre-incubated for 24h in minimum essential media (MEM) supplemented with 10% FBS and 1% penicillin-streptomycin (sMEM). Pre-osteoblasts (MC3T3-E1) were seeded at 50,000 cells/cm2 and after a cell adhesion period of 2h, flow was applied for 72h through the chip at different rates: 2, 8 and 14 μl/min. A static (0 μl/min) chip condition was included, where sMEM was manually replaced every 24h. CDHA discs (⌀=6mm, h=2mm) placed in a 96-well plate were used as a standard static control (200 μl sMEM replaced every 24h). At 6h and 72h, the cells were stained with a calcein, propidium iodide and Hoechst triple-stain to assess their adhesion and proliferation, respectively. In a separate experiment, sMEM was flown through the chips for 24h at the aforementioned flow rates, and Ca2+ concentration was quantified via inductively coupled plasma-optical emission spectroscopy (ICP-OES). As control, sMEM in contact with CDHA discs for 24h was evaluated.

    RESULTS:

    A larger number of cells adhered on the CDHA-on-chip under flow as opposed to both static CDHA-on-chip and CDHA disc in a well plate. Differences in cell adhesion between the flow conditions were negligible. Cell proliferation at 72h was significantly increased under flow compared to CDHA disc samples (Fig.1A). Static CDHA-on-chip showed almost no viable cells. 2 and 8 μl/min flow conditions showed the greatest cell counts, followed by the 14 μl/min flow condition. At higher flow rates, Ca2+ concentrations were closer to in fresh medium (Fig.1B)

    DISCUSSION & CONCLUSIONS:

    The static CDHA-on-chip and disc samples displayed a low degree of cell adhesion and proliferation, which seemed to indicate that ionic exchange led to detrimental cell behaviour. Cells displayed the greatest degree of adhesion and proliferation at a flow rate of 2 and 8 μl/min, probably due to more optimal Ca2+ concentrations. At 14 μl/min, the degree of cell adhesion and proliferation decreased, which could be ascribed to adverse effects of shear stress.

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  • 13.
    Atif, Abdul Raouf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Pujari-Palmer, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Tenje, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Quantitative evaluation of osteoblast proliferation and differentiation on a biomaterial in a microfluidic device2020Conference paper (Other academic)
    Abstract [en]

    Introduction

    Calcium phosphate cements (CPCs) are able to transform into calcium deficient hydroxyapatite (CDHA), whose crystal size and chemistry closely matches that of the inorganic phase of bone [1]. CDHA readily uptakes calcium ions, and releases phosphate, when immersed in synthetic solutions that mimic physiological fluids [1]. While CPCs are able to enhance bone regeneration in defect sites located in non-load bearing areas, the ionic imbalance that arises from dissolution may also have detrimental effects on cell behavior and function. The purpose of this study was to culture cells on CDHA embedded in a microfluidic chip, under flow, to sustain optimal ionic concentrations, and subsequently evaluate cell proliferation and differentiation.   

    Methods

    CPC was cast into a polydimethylsiloxane (PDMS) pocket (h = 0.8 mm) and then set in a 0.9 % NaCl(aq) solution at 37°C for 10 days leading to conversion into CDHA. The CDHA embedded in PDMS were dried and bonded to glass via oxygen plasma treatment, resulting in chips with a 0.5 mm deep channel above the CDHA. In parallel, CDHA discs (⌀ = 6 mm) were set in Teflon molds for the same period of time. The CDHA chips and discs were sterilized with ethanol and pre-incubated with cell culture media overnight. MC3T3-E1 pre-osteoblasts (50,000 cells/cm2) were seeded on the CDHA, and allowed to adhere for 2 h, before initiating a flow of 8 µl/min. Cell proliferation (indirectly measured as the cytosolic lactate dehydrogenase (LDH) enzyme of cells previously adhered to the material) and cell differentiation (alkaline phosphatase activity normalized by total amount of protein) were quantified on day 1, 5 and 10. On day 10, cells were stained with Calcein, Propidium iodide (live/dead assay) and Hoechst (nucleus), and were imaged via fluorescence microscopy.   

    Results

    The fabrication of the CDHA-on-chip was successful (Fig 1A). There was a faster increase of osteoblast growth on the CDHA-on-chip (under flow) than on discs (static conditions). Specifically, between day 5 and 10, cell number on-chip increased a two-fold as compared to the insignificant change on discs (Fig 1B). Cells on-chip were observed confluent at day 10 (Fig 1C) and seemed to differentiate over time (not shown).

    Conclusion

    The integrated hydroxyapatite platform is a potential alternative for standard in vitro analysis using well plates. Application of flow ameliorates media ionic imbalance, while also providing fresh nutrients and removing waste.

  • 14.
    Atif, Abdul-Raouf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Lacis, Ugis
    KTH Royal Inst Technol, FLOW Ctr, Dept Engn Mech, S-11428 Stockholm, Sweden..
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Tenje, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Bagheri, Shervin
    KTH Royal Inst Technol, FLOW Ctr, Dept Engn Mech, S-11428 Stockholm, Sweden..
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Experimental Characterization and Mathematical Modeling of the Adsorption of Proteins and Cells on Biomimetic Hydroxyapatite2022In: ACS Omega, E-ISSN 2470-1343, Vol. 7, no 1, p. 908-920Article in journal (Refereed)
    Abstract [en]

    Biomaterial development is a long process consisting of multiple stages of design and evaluation within the context of both in vitro and in vivo testing. To streamline this process, mathematical and computational modeling displays potential as a tool for rapid biomaterial characterization, enabling the prediction of optimal physicochemical parameters. In this work, a Langmuir isotherm-based model was used to describe protein and cell adhesion on a biomimetic hydroxyapatite surface, both independently and in a one-way coupled system. The results indicated that increased protein surface coverage leads to improved cell adhesion and spread, with maximal protein coverage occurring within 48 h. In addition, the Langmuir model displayed a good fit with the experimental data. Overall, computational modeling is an exciting avenue that may lead to savings in terms of time and cost during the biomaterial development process.

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    FULLTEXT01
  • 15.
    Bai, Xuan
    et al.
    Sichuan Univ, West China Hosp Stomatol, State Key Lab Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Natl Clin Res Ctr Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Dept Cariol & Endodont, Chengdu 610041, Peoples R China..
    Liu, Wenjuan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Hunan Univ Sci & Technol, Sch Mat Sci & Engn, Xiangtan 411201, Peoples R China.;Hunan Univ Sci & Technol, Hunan Prov Key Lab Controllable Preparat & Funct, Xiangtan 411201, Peoples R China..
    Xu, Laijun
    Sichuan Univ, West China Hosp Stomatol, State Key Lab Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Natl Clin Res Ctr Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Dept Cariol & Endodont, Chengdu 610041, Peoples R China..
    Ye, Qing
    Sichuan Univ, West China Hosp Stomatol, State Key Lab Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Natl Clin Res Ctr Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Dept Cariol & Endodont, Chengdu 610041, Peoples R China..
    Zhou, Huasi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Berg, Camilla
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Yuan, He
    Sichuan Univ, West China Hosp Stomatol, State Key Lab Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Natl Clin Res Ctr Oral Dis, Chengdu 610041, Peoples R China..
    Li, Jiyao
    Sichuan Univ, West China Hosp Stomatol, State Key Lab Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Natl Clin Res Ctr Oral Dis, Chengdu 610041, Peoples R China.;Sichuan Univ, West China Hosp Stomatol, Dept Cariol & Endodont, Chengdu 610041, Peoples R China..
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Sequential macrophage transition facilitates endogenous bone regeneration induced by Zn-doped porous microcrystalline bioactive glass2021In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 9, no 12, p. 2885-2898Article in journal (Refereed)
    Abstract [en]

    Macrophages play an important role in the immune microenvironment during bone healing, and sequential macrophage phenotypic transition could achieve superior osteogenic outcomes. Microcrystalline bioactive glasses (MCBGs) with osteoimmunomodulatory effects show potential in bone tissue regeneration. Zinc (Zn) has been approved to coordinate innate and adaptive immunity. Therefore, in this study, different amounts of ZnO were incorporated into microcrystalline bioactive glass to improve its immunomodulatory ability. The effect of Zn-MCBG ionic extracts on macrophage transition was studied, and the 5Zn-MCBG extracts could orchestrate sequential M1-to-M2 macrophage transition and promote the expression of proinflammatory and anti-inflammatory genes and cytokine expression to induce human bone marrow stromal cells (hBMSCs) osteogenic differentiation in vitro. Macroporous Zn-MCBG scaffolds containing mesopores were fabricated and showed good cell adhesion and feasible apatite formation when immersed in SBF in vitro. Furthermore, a rat calvarial defect model was used to confirm that the Zn-MCBG scaffold could modulate macrophage phenotypic transition and create a desirable osteogenic microenvironment to promote osteogenesis in vivo.

  • 16.
    Bang, Le T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Filho, Luimar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Synthesis and assessment of metallic ion migration through a novel calcium carbonate coating for biomedical implants2020In: Journal of Biomedical Materials Research. Part B - Applied biomaterials, ISSN 1552-4973, E-ISSN 1552-4981, Vol. 108, no 2, p. 429-438Article in journal (Refereed)
    Abstract [en]

    Titanium (Ti) implants are commonly regarded as well accepted by the body. However, metal ion release is still a cause for concern. A small decrease in pH, which can be caused by inflammation, may produce a large increase in the corrosion rate of Ti implants. Coating the alloy with a buffer layer could have a significant protective effect. In this study, a calcium carbonate coating was developed on commercially pure Ti and a Ti-6Al-4V alloy through a hydrothermal treatment of previously NaOH-treated surfaces in calcium-citric acid chelate complexes. The results showed that a superstructured calcite coating layer formed on the Ti substrate after treatment at 170 degrees C for 3 hr. The coating was approx. 1 mu m thick and covered the substrate surface uniformly. When prolonging the hydrothermal treatment from 5 hr to 24 hr, the rhombohedral structure of calcite was observed in addition to the superstructure of calcite. Dissolution test results showed no significant differences in solution pH between the coated- and un-coated samples. However, the CaCO3 coating reduced by approx. 2-5 times the Ti and V ion release from the substrate as compared to the uncoated material, at pH 4. CaCO3 and hydroxyapatite (HA) coatings gave nonsignificant effects at neutral pH although the HA coating showed a trend for better results at the longer time points. The reduction in metal ion release from the substrate and the buffering ability of the CaCO3 coating encourage further studies on this coating for clinical applications.

  • 17.
    Berg, Camilla
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Ceramic Core–Shell Particles: Synthesis and Use within Dentistry2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dentin hypersensitivity is one of the most prevalent conditions related to oral health, affecting a large share of the adult population. Shortcomings with the available treatment options are related to non-ideal particle sizes and degradation properties. An improved clinical outcome could possibly be obtained using a bioactive occluding agent that can offer a high, continuous release of ions, as well as having a particle size that allows for penetration into the dentin tubules. 

    The work in this thesis focused on the development and investigation of a synthesis approach for calcium phosphate core–shell particles and the use of those in the treatment of dentin hypersensitivity. The overall aim was to increase the knowledge about the synthesis and to evaluate the in vitro performance of amorphous calcium magnesium phosphate (ACMP) particles when used as an occluding agent. 

    The synthesis of the core-shell particles was based on precipitation reactions in aqueous solutions and the synthesized materials were studied in terms of morphological, structural, and compositional aspects. Resulting particles had diameters ranging from 400 nm–1. 5 µm (depending on reaction conditions), with morphologies and structures that were shown to correlate with the ionic radius and the concentration of the substituting ion. This insight resulted in the possibility to control the outcome of the reaction and to extend the synthesis to other alkaline earth phosphates. The mechanism of formation was suggested to be the simultaneous precipitation of primary nanoparticles (NPs) and the formation of gas bubbles that could function as soft templates.

    A study of the degradation properties together with a series of in vitro studies, using a dentin-disc model, indicated that the ACMP particles may be a promising candidate for clinical use. The material was shown to offer a rapid and continuous release of Ca2+, Mg2+, and phosphate, aiding surface, as well as intratubular occlusion and mineralization. Additional use of a fluoride toothpaste resulted in incorporation of F in the mineralized material. This could enhance the in vivo performance due to the known benefits of including F in dental tissues, e.g. decreased solubility. The ACMP particles were, furthermore, shown to be more efficient in terms of degree of occlusion when compared to other similar products available on the market. The intratubular mineralization was additionally mitigating the effect of an acid attack, which is of importance for a long-lasting effect in clinical use.

    List of papers
    1. Bubble-assisted fabrication of calcium phosphate core–shell particles
    Open this publication in new window or tab >>Bubble-assisted fabrication of calcium phosphate core–shell particles
    (English)Manuscript (preprint) (Other academic)
    National Category
    Engineering and Technology Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-437862 (URN)
    Available from: 2021-03-17 Created: 2021-03-17 Last updated: 2021-03-17
    2. Ion substitution induced formation of spherical ceramic particles
    Open this publication in new window or tab >>Ion substitution induced formation of spherical ceramic particles
    2019 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 45, no 8, p. 10385-10393Article in journal (Refereed) Published
    Abstract [en]

    How to precipitate ceramic nano- and microspheres in water based solutions only using inorganic ions is a challenge. In this study, spherical particles of alkaline earth phosphates and fluorides were synthesized using a precipitation reaction. Substituting ions, through inhibition of crystal growth, was used to induce sphere formation and to alter the morphology, size and composition of the spheres. The difference in ionic radius between the substituting ion (Mg, Ca and Sr) and the main cation (Sr and Ba) influenced the critical concentration to allow for sphere formation as well as the crystallinity. The larger difference, the lower was the concentration needed to form spheres. Low concentrations of Mg was enough to generate amorphous spheres of Sr- and Ba- phosphates whereas higher concentrations were needed if the radius difference were smaller. An increasing degree of substitution leads to a decrease in crystallinity of precipitated particles. The degree of substitution was determined to 16-55% where a low degree of ion substitution in the phosphates resulted in the formation of spheres (500-800 nm) with rough surfaces composed of apatite like phases. A higher degree of substitution resulted in amorphous spheres (500 nm- (1) mu m) with smooth surfaces.

    Place, publisher, year, edition, pages
    ELSEVIER SCI LTD, 2019
    Keywords
    Powders, Chemical preparation, Chemical properties
    National Category
    Ceramics
    Identifiers
    urn:nbn:se:uu:diva-383145 (URN)10.1016/j.ceramint.2019.02.097 (DOI)000465058500089 ()
    Funder
    Swedish Research Council, 2013-5419
    Available from: 2019-05-10 Created: 2019-05-10 Last updated: 2021-03-17Bibliographically approved
    3. Amorphous Calcium Magnesium Phosphate Particles for Treatment of Dentin Hypersensitivity: A Mode of Action Study
    Open this publication in new window or tab >>Amorphous Calcium Magnesium Phosphate Particles for Treatment of Dentin Hypersensitivity: A Mode of Action Study
    2020 (English)In: ACS Biomaterials Science & Engineering, E-ISSN 2373-9878, Vol. 6, no 6, p. 3599-3607Article in journal (Refereed) Published
    Abstract [en]

    Occlusion of exposed dentin tubules may eliminate or reduce dentin hypersensitivity by hindering fluid movements within the tubules. In this study, the mode of action of spherical particles of amorphous calcium magnesium phosphate (180-440 nm in diameter) was studied. A degradation study of the particles in Tris-HCl buffer showed that the particles continuously released Ca2+, Mg2+, and phosphate, and XRD analysis revealed the formation of hydroxyapatite (HA) after 1 week. The occluding effect and efficacy of the spherical particles as an occluding agent were evaluated in an in vitro study. The ACMP particles were incorporated in a gel intended for at-home use and tested on extracted human molars. Application of the particles followed by incubation in artificial saliva resulted in occlusion of exposed tubules, and examination with SEM showed that the particles could penetrate the tubules down to 100 mu m from the dentin surface. Transformation of the particles into nanocrystalline HA-structures (nanoHA) was initiated at the dentin surface within 12 h of application, and tubule penetration of the particles, accompanied by further ion release and diffusion of ions, resulted in deep intratubular occlusion in the majority of the tubules within 3 days from application. NanoHA was tightly adhered to the tubule walls, filling the entire tubule volume after 7 days. The results of this study demonstrate the mode of action of the amorphous calcium magnesium phosphate particles in occluding exposed dentin tubules. Interaction with saliva and transformation of the particles within the tubules inducing further mineralization indicate that the particles may be used as an effective treatment to reduce dentin hypersensitivity.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2020
    Keywords
    dentin hypersensitivity, amorphous calcium phosphate, magnesium, remineralization, occlusion
    National Category
    Biomaterials Science Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-418842 (URN)10.1021/acsbiomaterials.0c00262 (DOI)000541442600031 ()
    Funder
    Swedish Research Council, 2017-04728_3
    Available from: 2020-09-15 Created: 2020-09-15 Last updated: 2022-02-10Bibliographically approved
    4. Electron microscopy evaluation of mineralization on peritubular dentin with amorphous calcium magnesium phosphate microspheres
    Open this publication in new window or tab >>Electron microscopy evaluation of mineralization on peritubular dentin with amorphous calcium magnesium phosphate microspheres
    Show others...
    2020 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 46, no 11, p. 19469-19475Article in journal (Refereed) Published
    Abstract [en]

    Dentin hypersensitivity can be reduced by the use of a remineralization agent to hinder movement of fluids within the dentin tubules. Penetration of particles into the tubules and a continuous release of Ca2+ and phosphate ions can induce the mineralization of a material mimicking the mineral component of dentin, sealing the tubules. In this work, we have used complementary electron microscopy techniques to investigate the ultrastructure of dentin and crystallization and occlusion effects when using amorphous calcium magnesium phosphate (ACMP) microspheres on extracted human molars. Application of the particles in a gel intended for athome use resulted in intra-tubular mineralization of a carbonate substituted hydroxyapatite (HA). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that crystallization was initiated on the peritubular dentin (PTD) with undirected crystal growth leading to the formation of a porous material. We additionally investigated the effects from using a fluoride toothpaste to potentially improve the remineralization and anti-cariogenic properties of the ACMP microspheres. Energy dispersive x-ray spectroscopy (EDX) using TEM in scanning mode (STEM) showed that fluoride incorporation resulted in an increase in aspect ratio of the crystals, crystal growth directed towards the center of the tubule lumen and densification of the mineralized material. Thus, ACMP microspheres are promising alternatives as occluding agents and the efficacy of the particles could be further improved with the complementary use of a fluoride toothpaste.

    Keywords
    Dentin, Peritubular dentin, Electron microscopy, Occlusion, Amorphous calcium phosphate, Fluoride
    National Category
    Materials Chemistry Ceramics Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-417827 (URN)10.1016/j.ceramint.2020.04.295 (DOI)000537564300126 ()
    Funder
    Swedish Research Council, 2017-04728_3The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), CH2015-6394
    Available from: 2020-08-28 Created: 2020-08-28 Last updated: 2021-03-17Bibliographically approved
    5. Comparative study of technologies for tubule occlusion and treatment of dentin hypersensitivity
    Open this publication in new window or tab >>Comparative study of technologies for tubule occlusion and treatment of dentin hypersensitivity
    2021 (English)In: Journal of Functional Biomaterials, E-ISSN 2079-4983, Vol. 12, no 2, article id 27Article in journal (Refereed) Published
    Abstract [en]

    This study aimed to evaluate the occluding/remineralization performance and resistance to acid attacks of the mineralization layer formed by a tooth-desensitizing gel containing amorphous calcium magnesium phosphate (ACMP) particles and compare it to six other desensitizing products available on the market. Similar comprehensive studies are few and there is especially a lack of studies that are up to date. A dentin-disc model was used for in vitro evaluation of the desensitizing toothpastes/gels. Application of the products was performed twice daily for seven days. One set of specimens were evaluated using scanning electron microscopy (SEM) directly after the final treatment and another set was evaluated after an acid challenge, exposing specimens to 2 wt% citric acid. The ACMP desensitizing gel was the only product resulting in complete occlusion by the formation of mineralized material on the dentin surface and inside the tubules. Particle deposition was dominant after treatment with the other desensitizing products, with little or no mineralization, resulting in partial occlusion only. Sensodyne Repair & Protect and Oral-B Pro-Expert showed the highest resistance toward acid attacks. Material inside the tubules remained relatively unaffected by acid attacks in all specimens. The results in this study indicated a great variability among the occluding agents in terms of occlusion and acid resistance of the mineralization layer. The high degree of occlusion and intra-tubular mineralization that could mitigate the effect of acid solubilization indicate that the ACMP desensitizing gel may be a superior option for the treatment of dentin hypersensitivity.

    Place, publisher, year, edition, pages
    MDPI, 2021
    National Category
    Dentistry Biomaterials Science
    Research subject
    Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-437985 (URN)10.3390/jfb12020027 (DOI)000665503500001 ()33925548 (PubMedID)
    Funder
    Swedish Research Council, 2017-04728
    Available from: 2021-03-17 Created: 2021-03-17 Last updated: 2024-05-02Bibliographically approved
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  • 18.
    Berg, Camilla
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Fu, Le
    Cent South Univ, Sch Mat Sci & Engn, Changsha, Peoples R China.
    Liu, Yihong
    Peking Univ Sch, Dept Gen Dent, Beijing 100081, Peoples R China.;Hosp Stomatol, Beijing 100081, Peoples R China..
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Bulk nanobubbles as soft templates in the fabrication of inorganic core-shell particles2023In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 49, no 11, p. 16501-16513Article, review/survey (Refereed)
    Abstract [en]

    Hollow microstructured-and nanostructured-materials (also known as core-shell particles) have got great attention as advanced materials due to their fascinating physicochemical properties and favourable application prospects in many fields. In recent years, a variety of synthesis strategies have been explored to fabricate core-shell particles with different morphologies, compositions, microstructures, and thereby versatile functionalities. Among the synthesis strategies, soft-templating with the usage of nanobubbles is a feasible and effective one. Many inorganic core-shell particles have been prepared by using nanobubbles as a template. Nevertheless, studies in this field have not been reviewed comprehensively yet. Herein, the paper firstly reviewed several critical aspects of nanobubbles, such as the formation methods, stability and stabilization strategies of nano-bubbles; Secondly, characteristics of core-shell particles prepared by using nanobubbles soft template were summarized, including formation mechanisms, morphologies, etc.; Lastly, concerns regarding nanobubbles as soft templates were also briefly discussed.

    Download full text (pdf)
    fulltext
  • 19.
    Berg, Camilla
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Unosson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Amorphous Calcium Magnesium Phosphate Particles for Treatment of Dentin Hypersensitivity: A Mode of Action Study2020In: ACS Biomaterials Science & Engineering, E-ISSN 2373-9878, Vol. 6, no 6, p. 3599-3607Article in journal (Refereed)
    Abstract [en]

    Occlusion of exposed dentin tubules may eliminate or reduce dentin hypersensitivity by hindering fluid movements within the tubules. In this study, the mode of action of spherical particles of amorphous calcium magnesium phosphate (180-440 nm in diameter) was studied. A degradation study of the particles in Tris-HCl buffer showed that the particles continuously released Ca2+, Mg2+, and phosphate, and XRD analysis revealed the formation of hydroxyapatite (HA) after 1 week. The occluding effect and efficacy of the spherical particles as an occluding agent were evaluated in an in vitro study. The ACMP particles were incorporated in a gel intended for at-home use and tested on extracted human molars. Application of the particles followed by incubation in artificial saliva resulted in occlusion of exposed tubules, and examination with SEM showed that the particles could penetrate the tubules down to 100 mu m from the dentin surface. Transformation of the particles into nanocrystalline HA-structures (nanoHA) was initiated at the dentin surface within 12 h of application, and tubule penetration of the particles, accompanied by further ion release and diffusion of ions, resulted in deep intratubular occlusion in the majority of the tubules within 3 days from application. NanoHA was tightly adhered to the tubule walls, filling the entire tubule volume after 7 days. The results of this study demonstrate the mode of action of the amorphous calcium magnesium phosphate particles in occluding exposed dentin tubules. Interaction with saliva and transformation of the particles within the tubules inducing further mineralization indicate that the particles may be used as an effective treatment to reduce dentin hypersensitivity.

  • 20.
    Berg, Camilla
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Unosson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Comparative study of technologies for tubule occlusion and treatment of dentin hypersensitivity2021In: Journal of Functional Biomaterials, E-ISSN 2079-4983, Vol. 12, no 2, article id 27Article in journal (Refereed)
    Abstract [en]

    This study aimed to evaluate the occluding/remineralization performance and resistance to acid attacks of the mineralization layer formed by a tooth-desensitizing gel containing amorphous calcium magnesium phosphate (ACMP) particles and compare it to six other desensitizing products available on the market. Similar comprehensive studies are few and there is especially a lack of studies that are up to date. A dentin-disc model was used for in vitro evaluation of the desensitizing toothpastes/gels. Application of the products was performed twice daily for seven days. One set of specimens were evaluated using scanning electron microscopy (SEM) directly after the final treatment and another set was evaluated after an acid challenge, exposing specimens to 2 wt% citric acid. The ACMP desensitizing gel was the only product resulting in complete occlusion by the formation of mineralized material on the dentin surface and inside the tubules. Particle deposition was dominant after treatment with the other desensitizing products, with little or no mineralization, resulting in partial occlusion only. Sensodyne Repair & Protect and Oral-B Pro-Expert showed the highest resistance toward acid attacks. Material inside the tubules remained relatively unaffected by acid attacks in all specimens. The results in this study indicated a great variability among the occluding agents in terms of occlusion and acid resistance of the mineralization layer. The high degree of occlusion and intra-tubular mineralization that could mitigate the effect of acid solubilization indicate that the ACMP desensitizing gel may be a superior option for the treatment of dentin hypersensitivity.

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  • 21.
    Berg, Camilla
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Unosson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Electron microscopy evaluation of mineralization on peritubular dentin with amorphous calcium magnesium phosphate microspheres2020In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 46, no 11, p. 19469-19475Article in journal (Refereed)
    Abstract [en]

    Dentin hypersensitivity can be reduced by the use of a remineralization agent to hinder movement of fluids within the dentin tubules. Penetration of particles into the tubules and a continuous release of Ca2+ and phosphate ions can induce the mineralization of a material mimicking the mineral component of dentin, sealing the tubules. In this work, we have used complementary electron microscopy techniques to investigate the ultrastructure of dentin and crystallization and occlusion effects when using amorphous calcium magnesium phosphate (ACMP) microspheres on extracted human molars. Application of the particles in a gel intended for athome use resulted in intra-tubular mineralization of a carbonate substituted hydroxyapatite (HA). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that crystallization was initiated on the peritubular dentin (PTD) with undirected crystal growth leading to the formation of a porous material. We additionally investigated the effects from using a fluoride toothpaste to potentially improve the remineralization and anti-cariogenic properties of the ACMP microspheres. Energy dispersive x-ray spectroscopy (EDX) using TEM in scanning mode (STEM) showed that fluoride incorporation resulted in an increase in aspect ratio of the crystals, crystal growth directed towards the center of the tubule lumen and densification of the mineralized material. Thus, ACMP microspheres are promising alternatives as occluding agents and the efficacy of the particles could be further improved with the complementary use of a fluoride toothpaste.

  • 22.
    Berg, Camilla
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Yu, Shun
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Bubble-assisted fabrication of calcium phosphate core–shell particlesManuscript (preprint) (Other academic)
  • 23.
    Berglund, Sigrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Bassy, Clara
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Kaya, Ibrahim
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Andrén, Per E.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, MMS, Medical Mass Spectrometry. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Lasagna, Mauricio
    Department of Biochemistry and Biphysics, Texas A&M University.
    Tommos, Cecilia
    Department of Biochemistry and Biphysics, Texas A&M University.
    Magnuson, Ann
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Glover, Starla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hydrogen production by a fully de novo enzyme2024Manuscript (preprint) (Other academic)
    Abstract [en]

    Molecular catalysts based on abundant elements that function in neutral water represent an essential component of sustainable hydrogen production. Artificial hydrogenases based on protein-inorganic hybrids have emerged as an intriguing class of catalysts for this purpose. We have prepared a novel artificial hydrogenase based on cobaloxime bound to a de novo three alpha-helical protein, α3C, via a pyridyl-based unnatural amino acid. The functionalized de novo protein was characterised by UV-visible, CD, and EPR spectroscopy, as well as MALDI spectrometry, which confirmed the presence and ligation of cobaloxime to the protein. The new de novo protein produced hydrogen under electrochemical, photochemical and reductive chemical conditions in neutral water solution. A change in hydrogen evolution capability of the de novo enzyme compared with native cobaloxime was observed, with turnover numbers around 80% of that of cobaloxime, and hydrogen evolution rates of 40% of that of cobaloxime. We discuss these findings in the context of existing literature, how our study contributes important information about the functionality of cobaloxime as hydrogen evolving catalysts in protein environments, and the feasibility of using de novo proteins for developent into artificial metalloenzymes. Small de novo proteins as enzyme scaffolds have the potential to function as upscalable bioinspired catalysts thanks to their efficient atom economy, and the findings presented here show that these types of novel enzymes are a possible product. 

  • 24.
    Bergstedt, Edwin
    et al.
    KTH Royal Inst Technol, Dept Machine Design, Stockholm, Sweden..
    Holmberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Lindholm, Per
    KTH Royal Inst Technol, Dept Machine Design, Stockholm, Sweden..
    Olofsson, Ulf
    KTH Royal Inst Technol, Dept Machine Design, Stockholm, Sweden..
    Influence of the DIN 3962 Quality Class on the Efficiency in Honed Powder Metal and Wrought Steel Gears2020In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 63, no 6, p. 1076-1084Article in journal (Refereed)
    Abstract [en]

    To increase the efficiency of a gearbox, research on gear mesh loss is of importance. Britton et al. concluded that the surface finishing method affects the gear mesh efficiency. The efficiency benefits of superfinishing a surface and reducing the surface roughness have been reported by Kahraman. A novel method for calculating the bearing loss torque was proposed by Tu et al. Andersson et al. found that the efficiency can vary between 2 and 5% during repeated efficiency tests due to variations in the assembly process. This work investigates how the honing surface finishing process and DIN 3962 quality class affect the gear mesh efficiency by performing tests in an FZG back-to-back test rig. Two materials, a powder metal and a wrought steel, were tested. All gears were finished using a honing process and sorted according the measured quality class. Powder metal gears of class 6, 7, 8, and >= 9 and wrought steel gears of class 6, 7, and >= 9 were tested. The efficiency were calculated from measuring the torque required to maintain a constant velocity of the FZG test rig. The results from the efficiency tests showed no significant difference in efficiency between the wrought steel and powder metal steel gears. In addition, no obvious correlation between the DIN 3962 quality class and the gear mesh efficiency could be found. When examining the wrought steel material it was found that the reproducibility of the efficiency was comparable to the assembly error of the test rig, despite the variation in quality class.

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  • 25.
    Beyermann, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Microstructural characterization of quench annealed duplex SAF 2507 utilizing EBSD2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Producing large bars of duplex stainless steel free from precipitated embrittling phases isdifficult due to the many factors that influence precipitation. Research shows that intermetallicslike sigma and chi deteriorate principal material properties for the main application areas.Constructing a process with minimized precipitates is made more leisurely by understanding theevolution of the microstructure and the effects on precipitation. This thesis investigates themechanisms accompanying annealing at elevated temperatures, mainly recrystallization, phasetransformation, and grain growth. Compression samples of duplex SAF 2507 were annealed at900 ◦C and strained in Gleeble. Afterward, the annealing process split in two, (1) quenching withair and (2) heating to 1100 ◦C and soaking for various durations before controlled air cooling.EDS and EBSD in SEM were used to analyze the microstructures. EBSD data shows that mostof the sigma phase was dissolved after 2.5 min at 1100 ◦C when cooling with 2.3 ◦C/s. With thesame conditions, the recrystallization of austenite was complete. However, ferriterecrystallization was mostly complete after annealing at 900 ◦C with subsequent air-quenching.Austenite and ferrite grains showed tendencies of considerable pinning effects that inhibit graingrowth in both phases, expected of a two-phase material. During strain annealing at 900 ◦C,with a strain rate of 1/s, a reduction in the true stress-strain curve was observed. The reductionvaried for the samples if at all present, and for one specimen, the decrease was 75 MPa.Establishing the cause needs further investigation, but dynamic recrystallization is conceivable.

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  • 26.
    Bohlin, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Lifetime prediction of a polymeric propellant binder using the Arrhenius approach2021Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thermal-oxidative degradation of a crosslinked hydroxy-terminated polybutadiene (HTPB)/cycloaliphatic diisocyanate (H12MDI) based polymer, which is commonly used as a polymeric binder in propellants, is investigated at temperatures from 95°C to 125°C with the aim of estimating the lifetime of the material in storage conditions (20°C) using the Arrhenius approach. Furthermore, the effect of antioxidants and to a lesser extent plasticizer on the degradation process was also studied. Diffusion-limited oxidation (DLO) was theoretically modelled and DLO conditions were estimated by gathering oxygen permeability and consumption data from similar studies. It was concluded that DLO-effects might be present at the highest experiment temperature (125°C) depending on the actual properties of the material investigated. The mechanical degradation was monitored by conducting tensile tests in a DMA apparatus and photographs using a microscope was taken to examine potential DLO effects. The degradation process of the stabilized polymer (with antioxidant) did not showcase Arrhenius behaviour, which was confirmed by the failure to construct a satisfactory mastercurve. This was most likely due to loss of antioxidants, resulting in autocatalytic oxidation(acceleration of the oxidation process). However, the induction period of the stabilized polymer showcased Arrhenius behaviour in the temperature region 95-125°C with an ~E_a = 90 kJ/mol. If the activation energy E_a is assumed to remain constant, the lifetime at ambient temperature (20°C) is predicted to be approximately 176 Years for a 2mm thick sample. However, this is probably an overestimation since curvature in the Arrhenius plot has been observed for many rubber materials in the lower temperature region. Assuming the E_a drops from ~90 kJ/mol to~71 kJ/mol, a more conservative lifetime prediction of 58 Years was estimated.

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  • 27.
    Bojan, Alicja J.
    et al.
    Univ Gothenburg, Sahlgrenska Acad, Inst Clin Sci, Gothenburg, Sweden.;Sahlgrens Univ Hosp, Dept Orthopaed, Mölndal, Sweden..
    Stadelmann, Vincent A.
    Schulthess Klin, Dept Teaching Res & Dev, Zurich, Switzerland..
    Wu, Dan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Pujari-Palmer, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Insley, Gerard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Sundh, Daniel
    Univ Gothenburg, Inst Med, Dept Internal Med & Clin Nutr, Geriatr Med, Gothenburg, Sweden.;Sahlgrens Univ Hosp, Geriatr Med, Mölndal, Sweden..
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Procter, Philip
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    A new bone adhesive candidate- does it work in human bone?: An ex-vivo preclinical evaluation in fresh human osteoporotic femoral head bone2022In: Injury, ISSN 0020-1383, E-ISSN 1879-0267, Vol. 53, no 6, p. 1858-1866Article in journal (Refereed)
    Abstract [en]

    Introduction: The fixation of small intraarticular bone fragments is clinically challenging and an obvious first orthopaedic indication for an effective bone adhesive. In the present study the feasibility of bonding freshly harvested human trabecular bone with OsStic(R), a novel phosphoserine modified cement, was evaluated using a bone cylinder model pull-out test and compared with a commercial fibrin tissue adhesive. Methods: Femoral heads (n=13) were collected from hip fracture patients undergoing arthroplasty and stored refrigerated overnight in saline medium prior to testing. Cylindrical bone cores with a pre-inserted bone screw, were prepared using a coring tool. Each core was removed and glued back in place with either the bone adhesive (alpha-tricalcium phosphate, phosphoserine and 20% trisodium citrate solution) or the fibrin glue. All glued bones were stored in bone medium at 37 degrees C. Tensile loading, using a universal testing machine (5 kN load cell), was applied to each core/head. For the bone adhesive, bone cores were tested at 2 (n=13) and 24 (n=11) hours. For the fibrin tissue adhesive control group (n=9), bone cores were tested exclusively at 2 hours. The femoral bone quality was evaluated with micro-CT. Results: The ultimate pull-out load for the bone adhesive at 2 hours ranged from 36 to 171 N (mean 94 N, SD 42 N). At 24 hours the pull-out strength was similar, 47 to 198 N (mean 123 N, SD 43 N). The adhesive failure usually occurred through the adhesive layer, however in two samples, at 167 N and 198 N the screw pulled out of the bone core. The fibrin tissue adhesive group reached a peak force of 8 N maximally at 2 hours (range 2.8-8 N, mean 5.4 N, SD 1.6 N). The mean BV/TV for femoral heads was 0.15 and indicates poor bone quality. Conclusion: The bone adhesive successfully glued wet and fatty tissue of osteoporotic human bone cores. The mean ultimate pull-out force of 123 N at 24 hours corresponds to similar to 300 kPa shear stress acting on the bone core. These first ex-vivo results in human bone are a promising step toward potential clinical application in osteochondral fragment fixation. (C) 2022 The Authors. Published by Elsevier Ltd.

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  • 28.
    Borna, Arash
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Raman spectroscopy and refractive index: how it can be used to study blood2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This work was about Raman spectroscopy and refractive index and how they could be used tostudy healthy blood. The purpose of the paper was to study how Raman spectroscopy andrefractive index can be used to study blood. Subsequently, this was done through both aqualitative and quantitative study. The qualitative part was about gathering theory andintegrating it with the results. The quantitative part was conducted through empirics. Hence,Raman spectroscopy examined blood from a rabbit. Moreover, two scaffolds were built to studyhow the refractive index was affected by the blood. The result showed that Raman spectroscopyand refractive index both can be used to study blood in the present. Raman spectroscopy canexamine blood through intensity and wavenumber. Consequently, the refractive index shows thatthe larger the area of the blood sample, the smaller the refractive index.

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  • 29.
    Braesch-Andersen, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Wu, Dan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Ferguson, Stephen J.
    Swiss Fed Inst Technol, Inst Biomech, Zurich, Switzerland..
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Isaksson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Application of phase-field fracture theories and digital volume correlation to synchrotron X-ray monitored fractures in human trabecular bone: A case study2022In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 135, article id 105446Article in journal (Refereed)
    Abstract [en]

    Fracture processes of trabecular bone have been studied using various approaches over the years. However, reliable methods to analyse fracture at the single trabecula level are limited. In this study, a digital volume correlation (DVC) and a phase-field fracture model are applied and contrasted for human trabecular bone to analyse its failure under global compression at high resolution.A human trabecular bone sample was fractured in situ under synchrotron-based X-ray micro computed to-mography (CT). Reconstructed CT data was then used in DVC algorithms to obtain high-resolution displacement fields in the bone at different load steps. A high-resolution specimen-specific structural mesh was discretized from the CT data and used for the phase-field simulation of the fracturing bone.The DVC analysis showed opening mode cracks as well as shear mode cracks. Strains in cracked regions were analysed. The load distribution in the trabecular structure resulted in two completely separated fracture regions in the sample body. A phenomenon that was also captured in the phase-field model. The results encourage us to believe improvements in boundary conditions and material models are worthwhile pursuing. Findings in this study support further development of a phase-field method to analyse fracture in samples with complex morphology, such as trabecular bone, and the capacity of DVC to quantify strains and slowly growing stable fractures during step-wise loading of trabecular bone.

  • 30.
    Bremler, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Fatigue and microstructural study of a 316L austenitic stainless steel marine component produced by Wire Arc Additive Manufacturing (WAAM)2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this study, the fatigue- and fracture properties and microstructure of a marine component of austenitic stainless steel 316L manufactured with the novel method Wire Arc Additive Manufacturing were investigated and compared with data from literature. The purpose was to find a critical flaw size in the material related to its fatigue life.

    It was done by studying the microstructure and interpreting fatigue- and mechanical data for the marine component in empirical models related to the fatigue- and fracture properties. Fracture properties were approximated to estimate fatigue life and critical flaw size. Fatigue limit and fatigue threshold were based on hardness test data, fracture toughness, and FADs on Charpy-V impact test data.

    The material manufactured with Wire Arc Additive Manufacturing had superior fatigue properties than cast and rolled equivalents and performed better in the fatigue test than recommendations for austenitic stainless steel in a seawater environment from the British Standard 7910:2019. Due to the conservative model's fatigue limit and fatigue threshold, the results are conservative. The reason for that could be the crack closure properties of the material. The results for fracture toughness are lower than the literature data. This is most likely due to conservative models based on Charpy-V impact test data.

    The most important properties of the fatigue life are the fatigue limit and the fatigue threshold due to their relationship with crack growth. Testing the lifetime of the component in seawater is complex and time-consuming due to the corrosion and the need for low test frequency.

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  • 31.
    Carlsson, Gustav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    An MST approach to skin perforation using wet etched silicon microneedles2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The human skin functions as a strong barrier and when administering medical drugs through the skin a very high concentration of medicine is needed. With the use of microneedles the diffusivity can be increased. This project aims to manufacture microneedles with lasered holes in them, which could be used to increase the diffusivity and to lengthen the window of this increased diffusivity.

     

    Microneedles were wet etched from p-doped (100) silicon wafers in potassium hydroxide (KOH) using a square mask design. A laser cutter was used to create holes in the microneedles but it proved difficult to obtain sharp 90 degrees edges. The laser cutter was then used on plane silicon wafers with different protective thin films (molybdenum, silicon dioxide and a photoresist) to create holes with sharper edges. Lastly, the laser cutter was also used in combination with a deep etch on a plane silicon wafer coated with thin films of molybdenum and aluminium.

     

    Microneedles with a height of around 150 micrometers were able to be etched from a silicon wafer and the deep etch in combination with the laser cutter showed proof of concept in creating holes with sharp edges. Future work can be done to further increase the sharpness of the edges and to apply this method of creating holes directly on the microneedles.

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  • 32.
    Carter, Sarah-Sophia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology.
    Atif, Abdul Raouf
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology.
    Kadekar, Sandeep
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Lanekoff, Ingela
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Varghese, Oommen P.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Tenje, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Microsystems Technology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    PDMS leaching and its implications for on-chip studies focusing on bone regeneration applications2020In: Organs-on-a-Chip, ISSN 2666-1020, Vol. 2, article id 100004Article in journal (Refereed)
    Abstract [en]

    Polydimethylsiloxane (PDMS) is among the most widely used materials for organ-on-chip systems. Despite itsmultiple beneficial characteristics from an engineering point of view, there is a concern about the effect of PDMSon the cells cultured in such devices. The aim of this study was to enhance the understanding of the effect of PDMSon cellular behavior in a context relevant for on-chip studies. The focus was put on an indirect effect of PDMS,namely leaching of uncrosslinked oligomers, particularly for bone regeneration applications. PDMS-based chipswere prepared and analyzed for the potential release of PDMS oligomers within the microfluidic channel whenkept at different flow rates. Leaching of uncrosslinked oligomers from PDMS was quantified as silicon concen-tration by inductively coupled plasma - optical emission spectrometry and further confirmed by mass spec-trometry. Subsequently, PDMS-leached media, with a silicon concentration matching the on-chip experiment,were prepared to study cell proliferation and osteogenic differentiation of MC3T3-E1 pre-osteoblasts and humanmesenchymal stem cells. The silicon concentration initially detected in the media was inversely proportional tothe tested flow rates and decreased to control levels within 52 h. In addition, by curing the material overnightinstead of 2 h, regardless of the curing temperature (65 and 80 C), a large reduction in silicon concentration wasfound, indicating the importance of the PDMS curing parameters. Furthermore, it was shown that PDMS oligo-mers enhanced the differentiation of MC3T3-E1 pre-osteoblasts, this being a cell type dependent effect as nochanges in cell differentiation were observed for human mesenchymal stem cells. Overall, this study illustrates theimportance of optimization steps when using PDMS devices for biological studies, in particular PDMS curingconditions and extensive washing steps prior to an experiment.

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  • 33.
    Cedervall, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Manuel, Pascal
    Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Facil, Harwell Campus, Didcot OX11 0QX, England..
    Pomjakushin, Vladimir
    Paul Scherrer Inst, Lab Neutron Scattering & Imaging, CH-5232 Villigen, Switzerland..
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Haeussermann, Ulrich
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Andersson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Magnetic property changes of NdGa upon hydrogen absorption2024In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 109, no 13, article id 134434Article in journal (Refereed)
    Abstract [en]

    Rare earth monogallide (REGa) Zintl phases are attractive for their properties in hydrogen storage and magnetic cooling. However, the magnetic effects upon hydrogen additions in REGa are not well understood. This study aims to explore the magnetic effects in REGaHx using SQUID magnetometry and neutron powder diffraction. To avoid challenges due to absorption and high incoherent scattering in the neutron diffraction experiments, the compound NdGaDx (x = 0, 0.9, or 1.6) was chosen for examination. It was found that NdGa exhibits two ferromagnetic structures below the Curie temperature of 42 K. Just below 42 K the magnetic moments are oriented along the crystallographic c axis, and at 20 K a spin reorientation occurs where the moments turn similar to 30 degrees toward the a axis. Upon partial deuteration (x = 0.9), the magnetization decreases and two magnetic phases are observed, one intermediate incommensurate phase, and one canted ferromagnetic phase with the net magnetization aligning along the b axis. For the full deuteride (x = 1.6) only one incommensurate magnetic phase is observed at low temperatures. Magnetometry also reveals that there are no isotope effects when absorbing H or D. The absorption of H or D changes the Nd-Nd distances as well as the electronic structure, which results in a drastic change in the magnetic properties as compared to NdGa.

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  • 34.
    Chen, Zhang
    et al.
    Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Xiaoxiao, Zheng
    Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Jie, Cui
    Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061, China.
    Jiangwei, Liu
    School of Energy and Power Engineering, Shandong University, Jinan 250061, China.
    Duan, Tianbo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Baoqing, Zhang
    Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Zihao, Zhang
    Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Jafri, Hassan
    Department of Electrical Engineering, Mirpur University of Science and Technology (MUST), Mirpur Azad Jammu and Kashmir 10250, Pakistan.
    Papadakis, Raffaello
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. TdB Labs, Ultuna, Uppsala 75651, Sweden.
    Zhao, Qian
    Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061, China.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Shandong Technology Centre of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250101, China.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Making monolayer graphene photoluminescent by electron-beam-activated fluorination approach2023In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 608, article id 154593Article in journal (Refereed)
    Abstract [en]

    The past one and half decades have witnessed a tremendous development of graphene electronics, and the key to the success of graphene is its exceptional properties. The lacking of an inherent bandgap endows graphene with excellent electrical properties but considerably limits its applications in light-emitting and high-performance graphene-based devices. Herein, an approach for the direct writing of semiconducting and photoluminescent fluorinated graphene (C4F) patterns on monolayer graphene by an optimized electron-beam-activated fluorination technique is reported. A series of characterization approaches, such as atomic force microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy were used to demonstrate the successful preparation of C4F for maskless lithography. Specially, a sharp and strong photoluminescence located at the purple light range of ∼380 nm was observed in C4F, demonstrating a desirable semiconducting nature, and the bandgap was further confirmed by follow-up electrical measurements, where the C4F filed-effect transistor exhibited a p-type semiconductor behavior and significantly enhanced on/off ratio. Therefore, this work provides a novel technique for the fabrication of graphene devices for promising electronic and optoelectronic applications, but also opens a route towards the tailoring and engineering of electronic properties of graphene.

  • 35.
    Cheng, Kaiyuan
    et al.
    Chinese Acad Med Sci & Peking Union Med Coll, Peking Union Med Coll Hosp, Dept Orthopaed Surg, 1 Shuaifuyuan, Beijing 100730, Peoples R China.;Chinese Acad Med Sci & Peking Union Med Coll, 9 Dongdan 3rd Alley, Beijing 100730, Peoples R China..
    Zhu, Wei
    Chinese Acad Med Sci & Peking Union Med Coll, Peking Union Med Coll Hosp, Dept Orthopaed Surg, 1 Shuaifuyuan, Beijing 100730, Peoples R China..
    Weng, Xisheng
    Chinese Acad Med Sci & Peking Union Med Coll, Peking Union Med Coll Hosp, Dept Orthopaed Surg, 1 Shuaifuyuan, Beijing 100730, Peoples R China..
    Zhang, Linjie
    Chinese Acad Med Sci & Peking Union Med Coll, 9 Dongdan 3rd Alley, Beijing 100730, Peoples R China..
    Yang, Liu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Harbin Inst Technol, Natl Key Lab Sci & Technol Adv Composites Special, Harbin 150001, Peoples R China..
    Han, Chang
    Chinese Acad Med Sci & Peking Union Med Coll, 9 Dongdan 3rd Alley, Beijing 100730, Peoples R China..
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Injectable tricalcium phosphate/calcium sulfate granule enhances bone repair by reversible setting reaction2021In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 557, p. 151-158Article in journal (Refereed)
    Abstract [en]

    Towards repairing bone defects, calcium sulfate and calcium phosphate cement have been recognized as promising bone grafts. However, the current bone cements are generally lack of proper porosity for cell migration and new tissue formation. On the other hand, porous scaffold cannot be delivered by injection, which limits its use its clinical use. Herein, we develop a novel tricalcium phosphate/calcium sulfate granule to overcome the limitations of injectable cements and traditional scaffolds. The biocompatible granule underwent in situ self-setting to form scaffold with porous structure after injection. It con-tributes to calcium deposition and upregulation of osteogenic genes of mesenchymal stem cells in a time-dependent manner. Within three months, cavitary bone defects of distal rabbit femurs implanted the granules exhibited better bone formation than those with those implanted with autologous bone.

  • 36.
    Chlouba, Tomas
    et al.
    Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany.
    Shiloh, Roy
    Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany.
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Hamberg, Mathias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Kozák, Martin
    Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic.
    Hommelhoff, Peter
    Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany.
    Diamond-based dielectric laser acceleration2022In: Optics Express, E-ISSN 1094-4087, Vol. 30, no 1, p. 505-510Article in journal (Refereed)
    Abstract [en]

    The field of dielectric laser accelerators (DLA) garnered a considerable interest in the past six years as it offers novel opportunities in accelerator science and potentially transformative applications. Currently, the most widespread approach considers silicon-based structures due to their low absorption and high refractive index in the infrared spectral region and the well-developed silicon processing technology. In this paper we investigate a diamond as an alternative to silicon, mainly due to its considerably higher damage threshold. In particular, we find that our diamond grating allows a three times higher acceleration gradient (60 MeV/m) compared to silicon gratings designed for a similar electron energy. Using more complex geometries, GeV/m acceleration gradients are within reach for subrelativistic electrons.

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  • 37.
    Dahlberg, Tobias
    et al.
    Umeå Univ, Dept Phys, Umeå, Sweden..
    Malyshev, Dmitry
    Umeå Univ, Dept Phys, Umeå, Sweden..
    Andersson, Per Ola
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Swedish Def Res Agcy FOI, Umeå, Sweden.
    Andersson, Magnus
    Umeå Univ, Dept Phys, Umeå, Sweden..
    Biophysical Fingerprinting of Single Bacterial Spores using Laser Raman Optical Tweezers2020In: Chemical, biological, radiological, nuclear, and explosives (CBRNE) sensing XXI / [ed] Guicheteau, JA Howle, CR, SPIE-Intl Soc Optical Eng , 2020, article id 114160IConference paper (Refereed)
    Abstract [en]

    Spore-forming bacteria that cause diseases pose a danger in our society. When in spore form, bacteria can survive high temperatures and resist a plethora of disinfection chemicals. Effective disinfection approaches are thus critical. Since a population of bacterial spores is heterogeneous in many aspects, single spore analyzing methods are suitable when heterogeneous information cannot be neglected. We present in this work a high-resolution Laser Raman optical tweezers that can trap single spores and characterize their Raman spectra. We first evaluate our system by measuring Raman spectra of spores, and purified DNA and DPA. Thereafter, we expose Bacillus thuringiensis spores to peracetic acid, chlorine dioxide, and sodium hypochlorite, which are common disinfection chemicals. The data reveals how these agents change the constitutes of a spore over time, thus improving on the mode of action of these disinfection chemicals.

  • 38.
    Daly, Colin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Increased build rate by laser powder bed fusion of SSAB steel powder2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    SSAB has built a pilot gas atomization facility looking to expand their expertise of steel into the metal powder and additive manufacturing industry. Laser powder bed fusion is an additive manufacturing method that melts and fuse metal feedstock powder together layer by layer using a high intensity laser. The complex process requires optimization in order to be competitive. The process parameters laser power, scan speed, hatch distance and layer thickness largely govern the build rate and total production time. To increase the build rate, two iterations of test cubes with unique parameters sets were experimentally printed. Evaluation of relative density, porosity, microstructure, hardness and mechanical properties was performed. All results were compared to a reference parameter set previously studied. A candidate parameter set successfully increased the build rate by 116% while maintaining satisfactory material properties.

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    Exjobb SSAB FINAL
  • 39.
    Deng, Yin
    et al.
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;Cent South Univ, Key Lab Nonferrous Met Mat Sci & Engn Hunan Prov, Changsha 410083, Peoples R China..
    Zhu, Xin-wen
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China..
    Lai, Yi
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China..
    Guo, Yi-fan
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China..
    Fu, Le
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China..
    Xu, Guo-fu
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;Cent South Univ, Key Lab Nonferrous Met Mat Sci & Engn Hunan Prov, Changsha 410083, Peoples R China..
    Huang, Ji-wu
    Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;Cent South Univ, Key Lab Nonferrous Met Mat Sci & Engn Hunan Prov, Changsha 410083, Peoples R China..
    Effects of Zr/(Sc plus Zr) microalloying on dynamic recrystallization, dislocation density and hot workability of Al-Mg alloys during hot compression deformation2023In: Transactions of Nonferrous Metals Society of China, ISSN 1003-6326, E-ISSN 2210-3384, Vol. 33, no 3, p. 668-682Article in journal (Refereed)
    Abstract [en]

    The deformation behavior and microstructure characteristics of Al-6.00Mg, Al-6.00Mg-0.10Zr and Al-6.00Mg-0.25Sc-0.10Zr (wt.%) alloys were investigated by hot compression tests and electron microscopy methods. The results show that after deforming under the maximum processing efficiency condition (673 K, 0.01 s-1), dislocation densities of Al-6.00Mg, Al-6.00Mg-0.10Zr and Al-6.00Mg-0.25Sc-0.10Zr alloys are 2.68x1016, 8.93x1016 and 6.1x1017 m-2, respectively. Their dynamic recrystallization fractions are 19.8%, 15.0% and 12.7%, respectively. Kernel average misorientation (KAM) analyses indicate that dislocation accumulation near grain boundaries is enhanced by adding Zr or Sc+Zr. Besides, the established hot processing maps, based on the dynamic material model (DMM), reveal that the addition of Zr or Sc+Zr can reduce the range of low-temperature unstable domain but expand the unstable domain at high temperatures and high strains. The experimental results further verify that under the testing deformation condition, only the Al-6.00Mg-0.25Sc-0.10Zr alloy cracks at 773 K and 1 s-1.

  • 40.
    Dettenrieder, Carina
    et al.
    Ulm University, Germany.
    Türkmen, Dervis
    Ulm University, Germany.
    Mattsson, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Mizaikoff, Boris
    Ulm University, Germany.
    Determination of volatile organic compounds in water by attenuated total reflection infrared spectroscopy and diamond-like carbon coated silicon wafers2020In: Chemosensors, ISSN 2227-9040, Vol. 8, no 3, p. 1-17, article id 75Article in journal (Refereed)
    Abstract [en]

    Volatile organic compounds (VOCs) are one of the most commonly detected contaminants in water. The occurrence is mainly in gasoline and other petroleum-based products, fumigants, paints and plastics. Releases into the environment and the widespread use have an impact on the ecosystem such as humans and animals due to their toxicity, mutagenicity, and carcinogenicity. VOCs may persist in groundwater and may enter drinking water supplies. In this paper, a diamond-like carbon (DLC)-coated silicon waveguide in combination with a polymer film (ethylene/propylene copolymer, E/P-co) for enrichment of analytes was investigated to determine its suitability for ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopic detection of VOCs. The DLC film was fluorine-terminated enhancing the adhesion of the hydrophobic polymer to the waveguide surface. The analytes diffuse into the hydrophobic polymer whereas water is excluded from the emanating evanescent field. Therefore, direct detection in aqueous systems is enabled. Nine VOCs, i.e., ethylbenzene (EB), trichloroethylene (TCE), tetrachloroethylene (TeCE), the xylene isomers (p-xylene, pXYL; m-xylene, mXYL; o-xylene, oXYL), naphthalene (NAPH), toluene (TOL), and benzene (BENZ), were evaluated simultaneously qualitatively and quantitatively showing the potential of DLC coatings revealing high sensitivities in the low ppb to ppm concentration range, i.e., 50 ppb for TeCE. To the best of our knowledge, this is the first time of IR spectroscopic detection of VOCs in aqueous solutions using DLC-coated waveguides in combination with a hydrophobic polymer. By utilizing a DLC-coated waveguide, a versatile sensor for real-time monitoring in harsh environments such as effluents, leaking pipelines, and underground storage tanks is feasible due to response times within a few minutes.

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  • 41.
    Dey, Ananta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Mendalz, Amal
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Wach, Anna
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland.;Jagiellonian Univ, SOLARIS Natl Synchrotron Radiat Ctr, Krakow, Poland..
    Vadell, Robert Bericat
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Silveira, Vitor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Leidinger, Paul Maurice
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Huthwelker, Thomas
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Novotny, Zbynek
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Artiglia, Luca
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Marcina Kasprzaka 44-52, PL-01224 Warsaw, Poland..
    Hydrogen evolution with hot electrons on a plasmonic-molecular catalyst hybrid system2024In: Nature Communications, E-ISSN 2041-1723, Vol. 15, article id 445Article in journal (Refereed)
    Abstract [en]

    Plasmonic systems convert light into electrical charges and heat, mediating catalytic transformations. However, there is ongoing controversy regarding the involvement of hot carriers in the catalytic process. In this study, we demonstrate the direct utilisation of plasmon hot electrons in the hydrogen evolution reaction with visible light. We intentionally assemble a plasmonic nanohybrid system comprising NiO/Au/[Co(1,10-Phenanthrolin-5-amine)2(H2O)2], which is unstable at water thermolysis temperatures. This assembly limits the plasmon thermal contribution while ensuring that hot carriers are the primary contributors to the catalytic process. By combining photoelectrocatalysis with advanced in situ spectroscopies, we can substantiate a reaction mechanism in which plasmon-induced hot electrons play a crucial role. These plasmonic hot electrons are directed into phenanthroline ligands, facilitating the rapid, concerted proton-electron transfer steps essential for hydrogen generation. The catalytic response to light modulation aligns with the distinctive profile of a hot carrier-mediated process, featuring a positive, though non-essential, heat contribution. Direct participation of plasmon-induced hot electrons in the photoelectrocatalytic synthesis of hydrogen. This report solves a long-lasting contentious issue surrounding plasmonic materials on catalytic applications.

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  • 42.
    Dey, Ananta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Silveira, Vitor R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Bericat Vadell, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Shtender, Vitalii
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Görlin, Mikaela
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Marcina Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Exploiting hot electrons from a plasmon nanohybrid system for the photoelectroreduction of CO22024In: Communications Chemistry, E-ISSN 2399-3669, Vol. 7, no 1, article id 59Article in journal (Refereed)
    Abstract [en]

    Plasmonic materials convert light into hot carriers and heat to mediate catalytic transformation. The participation of hot carriers (photocatalysis) remains a subject of vigorous debate, often argued on the basis that carriers have ultrashort lifetime incompatible with drive photochemical processes. This study utilises plasmon hot electrons directly in the photoelectrocatalytic reduction of CO2 to CO via a Ppasmonic nanohybrid. Through the deliberate construction of a plasmonic nanohybrid system comprising NiO/Au/ReI(phen-NH2)(CO)3Cl (phen-NH2 = 1,10-Phenanthrolin-5-amine) that is unstable above 580 K; it was possible to demonstrate hot electrons are the main culprit in CO2 reduction. The engagement of hot electrons in the catalytic process is derived from many approaches that cover the processes in real-time, from ultrafast charge generation and separation to catalysis occurring on the minute scale. Unbiased in situ FTIR spectroscopy confirmed the stepwise reduction of the catalytic system. This, coupled with the low thermal stability of the ReI(phen-NH2)(CO)3Cl complex, explicitly establishes plasmonic hot carriers as the primary contributors to the process. Therefore, mediating catalytic reactions by plasmon hot carriers is feasible and holds promise for further exploration. Plasmonic nanohybrid systems can leverage plasmon’s unique photophysics and capabilities because they expedite the carrier’s lifetime.

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  • 43.
    Diez-Escudero, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Andersson, Brittmarie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Hailer, Nils
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
    Hexagonal pore geometry and the presence of hydroxyapatite enhance deposition of mineralized bone matrix on additively manufactured polylactic acid scaffolds2021In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 125, article id 112091Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing (AM) has revolutionized the design of regenerative scaffolds for orthopaedic applications, enabling customizable geometric designs and material compositions that mimic bone. However, the available evidence is contradictory with respect to which geometric designs and material compositions are optimal. There is a lack of studies that systematically compare different pore sizes and geometries in conjunction with the presence or absence of calcium phosphates. We therefore evaluated the physicochemical and biological properties of additively manufactured scaffolds based on polylactic acid (PLA) in combination with hydroxyapatite (HA). HA was either incorporated in the polymeric matrix or introduced as a coating, yielding 15 and 2% wt., respectively. Pore sizes of the scaffolds varied between 200 and 450 um and were shaped either triangularly or hexagonally. All scaffolds supported the adhesion, proliferation and differentiation of both primary mouse osteoblasts and osteosarcoma cells up to four weeks, with only small differences in the production of alkaline phosphatase (ALP) between cells grown on different pore geometries and material compositions. However, mineralization of the PLA scaffolds was substantially enhanced in the presence of HA, either embedded in the PLA matrix or as a coating at the surface level, and by larger hexagonal pores. In conclusion, customized HA/PLA composite porous scaffolds intended for the repair of critical size bone defects were obtained by a cost-effective AM method. Our findings indicate that the analysis of osteoblast adhesion and differentiation on experimental scaffolds alone is inconclusive without the assessment of mineralization, and the effects of geometry and composition on bone matrix deposition must be carefully considered in order to understand the regenerative potential of experimental scaffolds.

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  • 44.
    Diez-Escudero, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics. Uppsala Univ, Dept Mat Sci & Engn, Div Appl Mat Sci, Dag Hammarskjolds Vag 20, S-75237 Uppsala, Sweden..
    Harlin, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Isaksson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Porous polylactic acid scaffolds for bone regeneration: A study of additively manufactured triply periodic minimal surfaces and their osteogenic potential2020In: Journal of Tissue Engineering, ISSN 2041-7314, Vol. 11, article id 2041731420956541Article in journal (Refereed)
    Abstract [en]

    Three different triply periodic minimal surfaces (TPMS) with three levels of porosity within those of cancellous bone were investigated as potential bone scaffolds. TPMS have emerged as potential designs to resemble the complex mechanical and mass transport properties of bone. Diamond, Schwarz, and Gyroid structures were 3D printed in polylactic acid, a resorbable medical grade material. The 3D printed structures were investigated for printing feasibility, and assessed by morphometric studies. Mechanical properties and permeability investigations resulted in similar values to cancellous bone. The morphometric analyses showed three different patterns of pore distribution: mono-, bi-, and multimodal pores. Subsequently, biological activity investigated with pre-osteoblastic cell lines showed no signs of cytotoxicity, and the scaffolds supported cell proliferation up to 3 weeks. Cell differentiation investigated by alkaline phosphatase showed an improvement for higher porosities and multimodal pore distributions, suggesting a higher dependency on pore distribution and size than the level of interconnectivity.

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  • 45. Dong, Zhiyun
    et al.
    Wu, Dan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Luo, Jun
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science. Sichuan University.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Silk fibroin hydrogels induced and reinforced by acidic calcium phosphate: A simple way of producing bioactive and drug-loadable composites for biomedical applications2021In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 193, p. 433-440Article in journal (Refereed)
    Abstract [en]

    Silk fibroin (SF) hydrogels have attracted extensive interest in biomedical applications due to their biocompatibility and wide availability. However, their generally poor mechanical properties limit their utility. Here, injectable, ready-to-use SF-based composites, simultaneously induced and reinforced by acidic calcium phosphates, were prepared via a dual-paste system requiring no complex chemical/physical treatment. The composite was formed by mixing a monocalcium phosphate monohydrate paste with a β-tricalcium phosphate/SF paste. The conformational transition of SF in an acidic environment forms continuous networks, and the acidic calcium phosphate, brushite and monetite, formed simultaneously in the networks during mixing. The composites displayed a partly elastomeric compression behavior, with mechanical properties increasing with an increasing calcium phosphate and β-sheet content at the lower calcium phosphate contents evaluated (22.2–36.4 wt%). While the stiffness was still relatively low, the materials presented a high elasticity and ductility, and no failure at stresses in the range of failure stresses of trabecular bone. Furthermore, the calcium phosphate confers bioactivity to the material, and the composites with a promising in vitro cell response also showed potential as drug vehicles, using vancomycin as a model drug. These dual-paste systems exhibit potential utility in biomedical applications, such as bone void fillers and drug vehicles.

  • 46.
    Du, Wenzheng
    et al.
    Shandong Univ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Minist Educ, Qilu Hosp,Dept Gen Surg, Jinan, Peoples R China.
    Zhao, Chuanzong
    Shandong Univ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Minist Educ, Qilu Hosp,Dept Gen Surg, Jinan, Peoples R China.
    Liu, Kunpeng
    Shandong Univ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Minist Educ, Qilu Hosp,Dept Gen Surg, Jinan, Peoples R China.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Chen, Yougen
    Shandong Univ, Shandong Prov Hosp, Dept Urol, Jinan, Peoples R China.
    Bai, Yanwen
    Shandong Univ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Minist Educ, Qilu Hosp,Dept Gen Surg, Jinan, Peoples R China.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Qian, Zhao
    Shandong Univ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Minist Educ, Qilu Hosp,Dept Gen Surg, Jinan, Peoples R China.
    Defective and doped aluminum nitride monolayers for NO adsorption: Physical insight2020In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 753, article id 137592Article in journal (Refereed)
    Abstract [en]

    An atomistic insight into the pristine, defective and doped AlN monolayers for NO adsorption is conducted using Density Functional Theory. The adsorption energy of NO on N-vacancy monolayer (−7.374 eV) is much larger than that of pure AlN (−0.397 eV). The Al-vacancy or B-doped monolayer are likely to be utilized for NO sensing due to the favorable band gap changes (0.969 eV and 0.836 eV respectively) compared with the pure monolayer. This work is to give physical insight into the NO adsorption mechanism of AlN monolayer and help experimentalists to design better 2-D materials for molecular adsorption and/or sensing applications.

  • 47.
    Du, Xiaoyu
    et al.
    Swiss Fed Inst Technol, Inst Biomech, Zurich, Switzerland..
    Zhou, Yijun
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Li, Lingzhe
    Empa Swiss Fed Labs Mat Sci & Technol, Dubendorf, Switzerland.;Swiss Fed Inst Technol, Inst Struct Engn, Zurich, Switzerland..
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Ferguson, Stephen J.
    Swiss Fed Inst Technol, Inst Biomech, Zurich, Switzerland..
    The porous cantilever beam as a model for spinal implants: Experimental, analytical and finite element analysis of dynamic properties2023In: Mathematical Biosciences and Engineering, ISSN 1547-1063, E-ISSN 1551-0018, Vol. 20, no 4, p. 6273-6293Article in journal (Refereed)
    Abstract [en]

    Investigation of the dynamic properties of implants is essential to ensure safety and compatibility with the host's natural spinal tissue. This paper presents a simplified model of a cantilever beam to investigate the effects of holes/pores on the structures. Free vibration test is one of the most effective methods to measure the dynamic response of a cantilever beam, such as natural frequency and damping ratio. In this study, the natural frequencies of cantilever beams made of polycarbonate (PC) containing various circular open holes were investigated numerically, analytically, and experimentally. The experimental data confirmed the accuracy of the natural frequencies of the cantilever beam with open holes calculated by finite element and analytical models. In addition, two finite element simulation methods, the dynamic explicit and modal dynamic methods, were applied to determine the damping ratios of cantilever beams with open holes. Finite element analysis accurately simulated the damped vibration behavior of cantilever beams with open holes when known material damping properties were applied. The damping behavior of cantilever beams with random pores was simulated, highlighting a completely different relationship between porosity, natural frequency and damping response. The latter highlights the potential of finite element methods to analyze the dynamic response of arbitrary and complex structures, towards improved implant design.

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  • 48.
    Duan, Tianbo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Functionalized Graphene as Superlattice and Gas Sensor2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Graphene, an atomic-thin carbon sheet with carbon atoms tightly packed honeycomb-like lattice, has attracted enormous interest due to its unique chemical and physical properties. However, the intrinsic zero bandgap characteristic of graphene has so far prevented graphene from building effective electronic and optoelectronic devices. To address this concern, different functionalization methods have been proposed to modify the electronic properties of graphene. This thesis focuses on different graphene surface functionalizations and their applications in gas detections and superlattices.

    First of all, the surface cleanness of graphene plays a crucial role in the performance of graphene devices. To achieve a controlled removal of polymer residues on graphene surface, a facile solvent based method has been proposed, which can drastically improve the charge carrier mobility of graphene devices by a factor of 3, indicating a potential ballistic transport of graphene under ambient condition. In addition, an electron beam induced fluorination cycle is proposed to eliminate the airborne hydrocarbon contamination related to aging effects on the graphene surface. Subsequent spectroscopic analysis confirms the long-term preservation of graphene using such technique. 

    A similar technique, ion beam induced covalent functionalization has been used to locally fluorinate graphene, which could enhance the sensitivity of NH3 sensing as compared to a pristine graphene gas sensor by a factor of 8. The use of non-covalent, π-π stacking interactions for the functionalization of graphene opens a pathway to bind the functionalizing groups from nearly unlimited variety of p conjugated molecules. Here, we demonstrate that the use of BP2T molecules functionalizing graphene leads to an enhanced sensitivity to NH3 by a factor of 3 comparing with that of pristine graphene. 

    This particle beam induced functionalization technique can be used for the fabrication of graphene superlattices. Here, a direct nanostructuring technique by employing electron beam induced etching with different precursor gases has been proposed to achieve localized structuring of graphene/hBN structures. Suspended fluorinated graphene can be obtained by using this dual-beam process, suggesting the capability of printing antidot superlattices where graphene would be suspended in a controllable way. When functionalizing a graphene bilayer by electron beam activated fluorination, a new type of moiré superlattice with rectangular periodicity can be formed due to the crystalline mismatch between the topmost fluorographene and underneath pristine graphene. Recently, rotational moiré superlattices of graphene were shown to be superconducting. We believe that this unique structure has the potential to equally reveal novel properties of 2D materials.

    List of papers
    1. Towards Ballistic Transport CVD Graphene by Controlled Removal of Polymer Residues
    Open this publication in new window or tab >>Towards Ballistic Transport CVD Graphene by Controlled Removal of Polymer Residues
    2022 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 33, no 49, p. 495704-Article in journal (Refereed) Published
    Abstract [en]

    Polymer-assisted wet transfer of chemical vapor deposited (CVD) graphene has achieved great success towards the true potential for large-scale electronic applications, while the lack of an efficient polymer removal method has been regarded as a crucial factor for realizing high carrier mobility in graphene devices. Hereby, we report an efficient and facile method to clean polymer residues on graphene surface by merely employing solvent mixture of isopropanol (IPA) and water (H2O). Raman spectroscopy shows an intact crystal structure of graphene after treatment, and the x-ray photoelectron spectroscopy indicates a significant decrease in the C–O and C=O bond signals, which is mainly attributed to the removal of polymer residues and further confirmed by subsequent atomic force microscopy analysis. More importantly, our gated measurements demonstrate that the proposed approach has resulted in a 3-fold increase of the carrier mobility in CVD graphene with the electron mobility close to 10 000 cm2 V−1 S−1, corresponding to an electron mean free path beyond 100 nm. This intrigues the promising application for this novel method in achieving ballistic transport for CVD graphene devices.

    Place, publisher, year, edition, pages
    IOP Publishing, 2022
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-439384 (URN)10.1088/1361-6528/ac8d9b (DOI)000855158800001 ()
    Available from: 2021-04-07 Created: 2021-04-07 Last updated: 2024-06-10Bibliographically approved
    2. Electron Beam Induced Fluorination Cycle for Long-term Preservation of Graphene under Ambient Condition
    Open this publication in new window or tab >>Electron Beam Induced Fluorination Cycle for Long-term Preservation of Graphene under Ambient Condition
    (English)Manuscript (preprint) (Other academic)
    National Category
    Physical Sciences Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-439385 (URN)
    Available from: 2021-04-07 Created: 2021-04-07 Last updated: 2021-04-07
    3. Enhanced Ammonia Gas Sensing Properties of Graphene via Ion‑Beam‑Induced Fluorination
    Open this publication in new window or tab >>Enhanced Ammonia Gas Sensing Properties of Graphene via Ion‑Beam‑Induced Fluorination
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Physical Sciences Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-439386 (URN)
    Available from: 2021-04-07 Created: 2021-04-07 Last updated: 2021-04-07
    4. Fabrication of BP2T Functionalized Graphene via Non-covalent π-π Stacking Interactions for Ammonia Detection
    Open this publication in new window or tab >>Fabrication of BP2T Functionalized Graphene via Non-covalent π-π Stacking Interactions for Ammonia Detection
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-439387 (URN)
    Available from: 2021-04-07 Created: 2021-04-07 Last updated: 2021-04-07
    5. Suspended Graphene Fabrication using Electron Beam Induced Etching with Different Precursor Gas
    Open this publication in new window or tab >>Suspended Graphene Fabrication using Electron Beam Induced Etching with Different Precursor Gas
    (English)Manuscript (preprint) (Other academic)
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-439508 (URN)
    Available from: 2021-04-07 Created: 2021-04-07 Last updated: 2021-04-16
    6. Direct Writing of Lateral Fluorographene Nanopatterns with Tunable Bandgaps and Its Application in New Generation of Moiré Superlattice
    Open this publication in new window or tab >>Direct Writing of Lateral Fluorographene Nanopatterns with Tunable Bandgaps and Its Application in New Generation of Moiré Superlattice
    Show others...
    2020 (English)In: Applied Physics Reviews, E-ISSN 1931-9401, ISSN 1931-9401, Vol. 7, article id 011403Article in journal (Refereed) Published
    Abstract [en]

    One of the primary goals for monolayer device fabrications and an ideal model of graphene as an atomic thin “canvas” is one that permits semiconducting/insulating lateral nanopatterns to be freely and directly drawn on the semimetallic graphene surface. This work demonstrates a reversible electron-beam-activated technique that allows direct writing of semiconducting/insulating fluorographene lateral nanopatterns with tunable bandgaps on the graphene surface with a resolution down to 9–15 nm. This approach overcomes the conventional limit of semiconducting C4F in the single-sided fluorination of supported graphene and achieves insulating C2F. Moreover, applying this technique on bilayer graphene demonstrates for the first time a new type of rectangular moiré pattern arising from the generated C2F boat/graphene superlattice. This novel technique constitutes a new approach to fabricating graphene-based flexible and transparent electronic nanodevices with the CxF channels utilized as semiconducting or insulating counterparts, and also opens a route toward the tailoring and engineering of electronic properties of such materials in addition to the dominating triangular moiré patterns from a graphene/hBN system.

    National Category
    Atom and Molecular Physics and Optics
    Identifiers
    urn:nbn:se:uu:diva-401434 (URN)10.1063/1.5129948 (DOI)000515505800001 ()
    Funder
    Swedish Research Council, 621-2012-3679Swedish Research Council, 2016-05259Knut and Alice Wallenberg FoundationSwedish Research Council Formas, 2019-01538Swedish National Infrastructure for Computing (SNIC)
    Available from: 2020-01-08 Created: 2020-01-08 Last updated: 2021-04-12Bibliographically approved
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  • 49.
    Duan, Tianbo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Daukiya, Lakshya
    Institut de Sciences des Matériaux de Mulhouse.
    Simon, Laurent
    Institut de Sciences des Matériaux de Mulhouse.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Enhanced Ammonia Gas Sensing Properties of Graphene via Ion‑Beam‑Induced FluorinationManuscript (preprint) (Other academic)
  • 50.
    Duan, Tianbo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Electron Beam Induced Fluorination Cycle for Long-term Preservation of Graphene under Ambient ConditionManuscript (preprint) (Other academic)
1234567 1 - 50 of 319
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