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  • 1.
    Abdellah, Mohamed
    et al.
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden.;South Valley Univ, Qena Fac Sci, Dept Chem, Qena 83523, Egypt..
    Poulsen, Felipe
    Univ Copenhagen, Dept Chem, DK-2100 Copenhagen, Denmark..
    Zhu, Qiushi
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Zhu, Nan
    Tech Univ Denmark, Dept Chem, Kemitorvet Bldg 207, DK-2800 Lyngby, Denmark.;Dalian Univ Technol, Zhang Dayu Sch Chem, Dalian 116024, Peoples R China..
    Zidek, Karel
    Acad Sci Czech Republ, Inst Plasma Phys, Reg Ctr Special Opt & Optoelect Syst TOPTEC, Za Slovankou 1782-3, Prague 18200 8, Czech Republic..
    Chabera, Pavel
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Corti, Annamaria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hansen, Thorsten
    Univ Copenhagen, Dept Chem, DK-2100 Copenhagen, Denmark..
    Chi, Qijin
    Tech Univ Denmark, Dept Chem, Kemitorvet Bldg 207, DK-2800 Lyngby, Denmark..
    Canton, Sophie E.
    DESY, Attosecond Sci Grp, Notkestr 85, D-22607 Hamburg, Germany.;ELI HU Nonprofit Ltd, ELI ALPS, Dugonics Ter 13, H-6720 Szeged, Hungary..
    Zheng, Kaibo
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden.;Qatar Univ, Coll Engn, Gas Proc Ctr, POB 2713, Doha, Qatar..
    Pullerits, Tonu
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Drastic difference between hole and electron injection through the gradient shell of CdxSeyZn1−xS1−y quantum dots2017Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, nr 34, s. 12503-12508Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ultrafast fluorescence spectroscopy was used to investigate the hole injection in CdxSeyZn1-xS1-y gradient core-shell quantum dot (CSQD) sensitized p-type NiO photocathodes. A series of CSQDs with a wide range of shell thicknesses was studied. Complementary photoelectrochemical cell measurements were carried out to confirm that the hole injection from the active core through the gradient shell to NiO takes place. The hole injection from the valence band of the QDs to NiO depends much less on the shell thickness when compared to the corresponding electron injection to n-type semiconductor (ZnO). We simulate the charge carrier tunneling through the potential barrier due to the gradient shell by numerically solving the Schrodinger equation. The details of the band alignment determining the potential barrier are obtained from X-ray spectroscopy measurements. The observed drastic differences between the hole and electron injection are consistent with a model where the hole effective mass decreases, while the gradient shell thickness increases.

  • 2.
    Ahlberg, Patrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Johansson, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Zhang, Zhibin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Lindblad, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Nyberg, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Defect formation in graphene during low-energy ion bombardment2016Ingår i: APL Materials, ISSN 2166-532X, Vol. 4, nr 4, artikel-id 046104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This letter reports on a systematic investigation of sputter induced damage in graphene caused by low energy Ar+ ion bombardment. The integral numbers of ions per area (dose) as well as their energies are varied in the range of a few eV's up to 200 eV. The defects in the graphene are correlated to the dose/energy and different mechanisms for the defect formation are presented. The energetic bombardment associated with the conventional sputter deposition process is typically in the investigated energy range. However, during sputter deposition on graphene, the energetic particle bombardment potentially disrupts the crystallinity and consequently deteriorates its properties. One purpose with the present study is therefore to demonstrate the limits and possibilities with sputter deposition of thin films on graphene and to identify energy levels necessary to obtain defect free graphene during the sputter deposition process. Another purpose is to disclose the fundamental mechanisms responsible for defect formation in graphene for the studied energy range.

  • 3.
    Ahlberg, Patrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Seung, Hee Jeong
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Jiao, Mingzhi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Wu, Zhigang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zhang, Zhi-Bin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Graphene as a Diffusion Barrier in Galinstan-Solid Metal Contacts2014Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 61, nr 8, s. 2996-3000Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the use of graphene as a diffusion barrier to a eutectic Ga-In-Sn alloy, i.e., galinstan, for electrical contacts in electronics. Galinstan is known to be incompatible with many conventional metals used for electrical contacts. When galinstan is in direct contact with Al thin films, Al is readily dissolved leading to the formation of Al oxides present on the surface of the galinstan droplets. This reaction is monitored ex situ using several material analysis methods as well as in situ using a simple circuit to follow the time-dependent resistance variation. In the presence of a multilayer graphene diffusion barrier, the Al-galinstan reaction is effectively prevented for galinstan deposited by means of drop casting. When deposited by spray coating, the high-impact momentum of the galinstan droplets causes damage to the multilayer graphene and the Al-galinstan reaction is observed at some defective spots. Nonetheless, the graphene barrier is likely to block the formation of Al oxides at the Al/galinstan interface leading to a stable electrical current in the test circuit.

  • 4.
    Ahlström, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Characterizing the state of water in an amorphous magnesium carbonate using Dielectric spectroscopy2013Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the industry of today, materials which can adsorb and hold large amounts of water are playing an important role. Here, the free and bound water carrying capacity of an amorphous magnesium carbonate is investigated. It is also determined how these parameters depend on the relative humidity of the surrounding environment. To do this, the technique of dielectric spectroscopy is employed. Along with the water binding properties, the concentration of charge carriers and the diffusion coefficient was determined. A smaller part of around 10-30 % of the water adsorbed was shown to behave as free water in the material. The concentration of charge carriers was calculated to be in an order of magnitude of 1018-1022 m-3 for the higher relative humidity environments. The diffusion coefficient was shown to be about 5*10-9 m2/s for the adsorption spectrum. This value is in good agreement with the value for OH- ions in water.

  • 5.
    Ahmadi, Majid
    et al.
    University of Puerto Rico.
    Sahoo, Satyaprakash
    University of Puerto Rico.
    Younesi, Reza
    Technical University of Denmark.
    Gaur, Anand P. S.
    Katiyar, Ram S.
    Guinel, Maxime J-F
    WO3 nano-ribbons: their phase transformation from tungstite (WO3·H2O) to tungsten oxide (WO3)2014Ingår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, nr 17, s. 5899-5909Artikel i tidskrift (Refereegranskat)
  • 6.
    Ahmadi, Majid
    et al.
    University of Puerto Rico.
    Younesi, Reza
    Technical University of Denmark.
    Guinel, Maxime J-F.
    University of Puerto Rico.
    Synthesis of tungsten oxide nanoparticles using a hydrothermal method at ambient pressure2014Ingår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 29, nr 13, s. 1424-1430Artikel i tidskrift (Refereegranskat)
  • 7. Ahrentorp, Fredrik
    et al.
    Blomgren, Jacob
    Zardán Gómez de la Torre, Teresa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Johansson, Christer
    Development of a sensitive induction based magnetic nanoparticlebiodetection method2018Ingår i: 12th International Conference on the Scientific and Clinical Applications of Magnetic Carriers, 2018Konferensbidrag (Refereegranskat)
  • 8. Ahrentorp, Fredrik
    et al.
    Blomgren, Jakob
    Jonasson, Christian
    Sarwe, Anna
    Sepehri, Sobhan
    Eriksson, Emil
    Kalaboukhov, Alexei
    Jesorka, Aldo
    Winkler, Dag
    Schneiderman, Justin F.
    Nilsson, Mats
    Albert, Jan
    Gómez de La Torre, Teresa Zardán
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Johansson, Christer
    Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils2017Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 427, nr Supplement C, s. 14-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abstract We use functionalized iron oxide magnetic multi-core particles of 100nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75min of amplification we obtain an average RCA coil diameter of about 1µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.

  • 9. Ahrentorp, Fredrik
    et al.
    Blomgren, Jakob
    Jonasson, Christian
    Sarwe, Anna
    Sepehri, Sobhan
    Eriksson, Emil
    Kalaboukhov, Alexei
    Jesorka, Aldo
    Winkler, Dag
    Schneiderman, Justin F.
    Nilsson, Mats
    Albert, Jan
    Zardán Gómez de la Torre, Teresa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strømme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Johansson, Christer
    Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils2017Ingår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 427, s. 14-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.

  • 10.
    Akhtar, Sultan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Rubino, Stefano
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Leifer, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    A simple TEM method for fast thickness characterization of suspendedgraphene flakesManuskript (preprint) (Övrigt vetenskapligt)
  • 11.
    Ali, Hasan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Towards atomically resolved magnetic measurements in the transmission electron microscope: A study of structure and magnetic moments in thin films2020Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The magnetic properties of thin metallic films are significantly different from the bulk properties due to the presence of interfaces. The properties shown by such thin films are influenced by the atomic level structure of the films and the interfaces. Transmission electron microscope (TEM) has the potential to analyse the structure and the magnetic properties of such systems with atomic resolution. In this work, the TEM is employed to characterize the structure of the Fe/V and Fe/Ni multilayers and the technique of electron magnetic circular dichroism (EMCD) is developed to obtain the quantitative magnetic measurements with high spatial resolution.

    From TEM analysis of short period Fe/V  multilayers, a coherent superlattice structure is found. In short period Fe/Ni multilayer samples with different repeat frequency, only the TEM technique could verify the existence of the multilayer structure in the thinnest layers. The methods of scanning TEM imaging and electron energy loss spectroscopy (EELS) results were used and refined to determine interdiffusion at the interfaces. The confirmation of the multilayer structure helped to explain the saturation magnetization of these samples.

    Electron magnetic circular dichroism (EMCD) has the potential to quantitatively measure the magnetic moments of the materials with atomic resolution, but the technique presents several challenges. First, the EMCD measurements need to acquire two EELS spectra at two different scattering angles. These spectra are mostly acquired one after the other which makes it difficult to guaranty the identical experimental conditions and the spatial registration between the two acquisitions. We have developed a technique to simultaneously acquire the two angle-resolved EELS spectra in a single acquisition. This not only ensures the accuracy of the measurements but also improves the signal to noise ratio as compared to the previously used methods. The second important question is the effect of crystal orientations on the measured EMCD signals, considering the fact that the crystal orientation of a real crystal does not remain the same in the measured area. We developed the methodology to simultaneously acquire the EMCD signals and the local crystal orientations with high precision and experimentally showed that the crystal tilt significantly changes the magnetic signal. The third challenge is to obtain EMCD measurements with atomic resolution  which is hampered by the need of high beam convergence angles. We further developed the simultaneous acquisition technique to obtain the quantitative EMCD measurements with beam convergence angles corresponding to atomic size electron probes. 

    Delarbeten
    1. Shrinking of silicon nanocrystals embedded in an amorphous silicon oxide matrix during rapid thermal annealing in a forming gas atmosphere
    Öppna denna publikation i ny flik eller fönster >>Shrinking of silicon nanocrystals embedded in an amorphous silicon oxide matrix during rapid thermal annealing in a forming gas atmosphere
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    2016 (Engelska)Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 27, nr 36, artikel-id 365601Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We report the effect of hydrogen on the crystallization process of silicon nanocrystals embedded in a silicon oxide matrix. We show that hydrogen gas during annealing leads to a lower sub-band gap absorption, indicating passivation of defects created during annealing. Samples annealed in pure nitrogen show expected trends according to crystallization theory. Samples annealed in forming gas, however, deviate from this trend. Their crystallinity decreases for increased annealing time. Furthermore, we observe a decrease in the mean nanocrystal size and the size distribution broadens, indicating that hydrogen causes a size reduction of the silicon nanocrystals.

    Nyckelord
    silicon nanocrystals, rapid thermal annealing, oxidation, forming gas, hydrogen, defects, passivation
    Nationell ämneskategori
    Materialteknik
    Identifikatorer
    urn:nbn:se:uu:diva-306271 (URN)10.1088/0957-4484/27/36/365601 (DOI)000384064400019 ()27478921 (PubMedID)
    Tillgänglig från: 2016-10-26 Skapad: 2016-10-26 Senast uppdaterad: 2019-12-06Bibliografiskt granskad
    2. Crystal perfection by strain engineering: The case of Fe/V (001)
    Öppna denna publikation i ny flik eller fönster >>Crystal perfection by strain engineering: The case of Fe/V (001)
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    2017 (Engelska)Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 636, s. 608-614Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We study the effect of bilayer thickness at fixed volume fraction on the structural quality of Fe/V (001)superlattices. We find that such artificial metallic superlattices can be manufactured with excellent crystalquality and layering up to at least 50 Å in repeat distance (K = LFe +LV). For an intended fixed ratio of theconstituents: LFe/LV= 1/7, out-of-plane coherence lengths comparable to the thicknesses of the sampleswere obtained. We evaluate the strain in- and out-of-plane of both layers as a function of the bilayer thicknessand comment on the growth using the framework of linear elasticity theory. We interpret the stabilityof the superlattice against crystal degradation due to the alternating compressive and tensile strain, yieldingclose to ideal lattice matching to the substrate.

    Nyckelord
    Superlattice; Iron/Vanadium; Sputtering; Epitaxy; Reciprocal space mapping; X-ray diffraction; X-ray reflectivity; Linear elasticity
    Nationell ämneskategori
    Annan materialteknik
    Identifikatorer
    urn:nbn:se:uu:diva-332050 (URN)10.1016/j.tsf.2017.07.005 (DOI)000408037800086 ()
    Tillgänglig från: 2017-10-23 Skapad: 2017-10-23 Senast uppdaterad: 2019-12-06Bibliografiskt granskad
    3. Composition, structure and magnetic properties of ultra-thin Fe/Ni multilayers sputter deposited on epitaxial Cu/Si(001)
    Öppna denna publikation i ny flik eller fönster >>Composition, structure and magnetic properties of ultra-thin Fe/Ni multilayers sputter deposited on epitaxial Cu/Si(001)
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    2018 (Engelska)Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 646, s. 117-125Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Sputter deposited symmetric multilayers of (n Fe)/(n Ni), with individual thicknesses from n = 4 to n = 48 monolayers (ML), were deposited on epitaxial Cu/Si(001), and their microstructural evolution and magnetic properties versus n have been studied. Elemental layering can be seen with transmission electron microscopy down to n = 4 ML layer thickness, although an intermixed region characterized by a finite interface width is found to be present. This width is composed of the interface roughness as well as the interdiffusion between layers, but the relative contributions from these two sources could not be concluded by the techniques used. The measured elemental layering and X-ray reflectivity (XRR) give an upper limit to the interface width which must be smaller than the thinnest layers, 4 ML. Electron energy loss spectroscopy (EELS), depth profiling X-ray photoelectron spectroscopy (XPS) and also XRR reveal that Fe has a higher tendency to mix with Ni than vice versa. XPS does not have the resolution to measure this thin elemental layering: composition variations for n = 8 ML which are clearly seen by EELS are barely resolved by XPS. The structure was determined by X-ray diffraction, and an epitaxial fcc (001) structure is found to be maintained throughout the multilayers up to n less than or similar to 8 ML. For larger n values, relaxation starts by Fe-fcc(001) layers changing into Fe-bcc(110), which is then followed by Ni-fcc(001) changing from (001) to (111) orientation along the growth direction. A decreased total measured magnetic moment for the fully epitaxial multilayers can be explained by the fcc Fe layers being partly anti-ferromagnetic, whereas the relaxed multilayers exhibit the expected magnetic properties of (bcc Fe) +(fcc Ni).

    Nationell ämneskategori
    Den kondenserade materiens fysik Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-305519 (URN)10.1016/j.tsf.2017.11.023 (DOI)000418575900017 ()
    Forskningsfinansiär
    Vetenskapsrådet
    Tillgänglig från: 2016-10-22 Skapad: 2016-10-18 Senast uppdaterad: 2019-12-06Bibliografiskt granskad
    4. Quantitative EMCD by use of a double aperture for simultaneous acquisition of EELS
    Öppna denna publikation i ny flik eller fönster >>Quantitative EMCD by use of a double aperture for simultaneous acquisition of EELS
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    2019 (Engelska)Ingår i: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 196, s. 192-196Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The weak signal strength in electron magnetic circular dichroism (EMCD) measurements remains one of the main challenges in the quantification of EMCD related EELS spectra. As a consequence, small variations in peak intensity caused by changes of background intervals, choice of method for extraction of signal intensity and equally differences in sample quality can cause strong changes in the EMCD signal. When aiming for high resolution quantitative EMCD, an additional difficulty consists in the fact that the two angular resolved EELS spectra needed to obtain the EMCD signal are taken at two different instances and it cannot be guaranteed that the acquisition conditions for these two spectra are identical.  Here, we present an experimental setup where we use a double hole aperture in the transmission electron microscope to obtain the EMCD signal in a single acquisition. This geometry allows for the parallel acquisition of the two electron energy loss spectra (EELS) under exactly the same conditions. We also compare the double aperture acquisition mode with the qE acquisition mode which has been previously used for parallel acquisition of EMCD. We show that the double aperture mode not only offers better signal to noise ratio as compared to qE mode but also allows for much higher acquisition times to significantly improve the signal quality which is crucial for quantitative analysis of the magnetic moments.

    Nationell ämneskategori
    Annan materialteknik
    Forskningsämne
    Materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-364715 (URN)10.1016/j.ultramic.2018.10.012 (DOI)000451180800026 ()30439606 (PubMedID)
    Forskningsfinansiär
    Vetenskapsrådet, C0367901Vetenskapsrådet, 2016-05259Knut och Alice Wallenbergs Stiftelse
    Tillgänglig från: 2018-10-31 Skapad: 2018-10-31 Senast uppdaterad: 2019-12-06Bibliografiskt granskad
    5. Simultaneous mapping of EMCD signals and crystal orientations in a transmission electron microscope
    Öppna denna publikation i ny flik eller fönster >>Simultaneous mapping of EMCD signals and crystal orientations in a transmission electron microscope
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    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Nanoteknik
    Identifikatorer
    urn:nbn:se:uu:diva-398559 (URN)
    Tillgänglig från: 2019-12-06 Skapad: 2019-12-06 Senast uppdaterad: 2019-12-06
    6. Atomic resolution electron probe magnetic circular dichroism measurements enabled by patterned apertures
    Öppna denna publikation i ny flik eller fönster >>Atomic resolution electron probe magnetic circular dichroism measurements enabled by patterned apertures
    Visa övriga...
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Nationell ämneskategori
    Nanoteknik
    Identifikatorer
    urn:nbn:se:uu:diva-398560 (URN)
    Tillgänglig från: 2019-12-06 Skapad: 2019-12-06 Senast uppdaterad: 2019-12-06
    7. An electron energy loss spectrometer based streak camera for time resolved TEM measurements
    Öppna denna publikation i ny flik eller fönster >>An electron energy loss spectrometer based streak camera for time resolved TEM measurements
    Visa övriga...
    2017 (Engelska)Ingår i: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 176, s. 5-10Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We propose an experimental setup based on a streak camera approach inside an energy filter to measure time resolved properties of materials in the transmission electron microscope (TEM). In order to put in place the streak camera, a beam sweeper was built inside an energy filter. After exciting the TEM sample, the beam is swept across the CCD camera of the filter. We describe different parts of the setup at the example of a magnetic measurement. This setup is capable to acquire time resolved diffraction patterns, electron energy loss spectra (EELS) and images with total streaking times in the range between 100 ns and 10 μs.

    Nyckelord
    Time resolved; TEM; Energy filter; Streak camera; Sweep
    Nationell ämneskategori
    Fysik Teknik och teknologier
    Identifikatorer
    urn:nbn:se:uu:diva-329982 (URN)10.1016/j.ultramic.2016.11.026 (DOI)000403992200003 ()
    Tillgänglig från: 2017-09-25 Skapad: 2017-09-25 Senast uppdaterad: 2019-12-06Bibliografiskt granskad
  • 12. Ali, Hasan
    et al.
    Negi, Devendra
    Warnatz, Tobias
    Hjörvarsson, Björgvin
    Rusz, Jan
    Leifer, Klaus
    Atomic resolution electron probe magnetic circular dichroism measurements enabled by patterned aperturesManuskript (preprint) (Övrigt vetenskapligt)
  • 13. Ali, Hasan
    et al.
    Rusz, Jan
    Warnatz, Tobias
    Hjörvarsson, Björgvin
    Leifer, Klaus
    Simultaneous mapping of EMCD signals and crystal orientations in a transmission electron microscopeManuskript (preprint) (Övrigt vetenskapligt)
  • 14.
    Ali, Hasan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Warnatz, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Xie, Ling
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Hjörvarsson, Björgvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Leifer, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Towards Quantitative Nanomagnetism in Transmission Electron Microscope by the Use of Patterned Apertures2019Ingår i: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 25, nr S2, s. 654-655Artikel i tidskrift (Övrigt vetenskapligt)
  • 15.
    Ali, Hasan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Xie, Ling
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    van Sebille, Martijn
    Delft University of Technology, Netherlands.
    Fusi, Adele
    Delft University of Technology, Netherlands.
    van Swaaij, Rene A C M M
    Delft University of Technology, Netherlands.
    Zeman, Miro
    Delft University of Technology, Netherlands.
    Leifer, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    TEM analysis of multilayered nanostructures formed in the rapid thermal annealed silicon rich silicon oxide film2016Ingår i: European Microscopy Congress 2016: Proceedings, 2016, s. 965-966Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Silicon (Si) nanoparticles (NPs) embedded in an ultrathin silicon rich silicon oxide (SRSO) film through the thermal annealing process has emerged as a highly absorbing layer for third-generation solar cells 1. The concept of using Si NPs is to achieve a band gap tunable absorber layer by controlling the size and structure of Si NPs because of the quantum confinement effect 2. In our study, a multilayer stack of silicon oxide with 35 periods of alternating layers of 1-nm thick near-stoichiometric and 3-nm thick Si-rich hydrogenated silicon oxide were deposited on fused quartz substrate by plasma-enhanced chemical vapor deposition (PECVD) method. Two samples were annealed using a rapid thermal annealing (RTA) furnace in forming gas atmosphere (90% N2 + 10% H2) for 210s and 270s respectively. From the Raman spectroscopy, a reduction in crystallinity of Si has been discovered from 210s annealed sample to 270s annealed sample (shown in Figure 2). The goal of transmission electron microscopy (TEM) analysis is to investigate the nanostructural change of Si in these two annealed samples and try to correlate the TEM observations to the Raman spectroscopy results.

    As the dimension of the Si nanostructures formed in SRSO films is in nanometer-scale, the energy-filtered TEM (EFTEM) tomography technique using the low-loss signals in electron energy-loss spectroscopy (EELS) has been applied as a powerful technique to correlate the precipitated Si nanostructures to the phase transformation mechanisms in the thermally annealed SRSO films 3. In this case, EFTEM spectrum-imaging (SI) technique was applied to characterize the Si nanostructures formed in SRSO films by different annealing times. The EFTEM SI dataset was acquired from -4eV to 40eV using a 2eV energy slit and the reconstructed zero loss peak (ZLP) was used to calibrate the spectra shift. Si plasmon images were extracted by fitting a Gaussian into the low-loss region with a peak position at 16.7 eV 4 and FWHM of 4.5 eV. In order to analyze the multilayer structures at different annealing durations, the TEM samples were prepared in cross sectional geometry using the conventional polishing and ion milling methods.

    Figure 1 shows the EFTEM images extracted from the Si plasmon peak, in these images Si appears as bright contrasts. For shorter annealing time, an alternating bright and dark contrast can be observed which indicates that the multilayer structure still remains whereas for longer annealing time, Si shows nanoparticles like contrast. The continuous layer like contrasts shown in Figure 1(a) indicates the overlapping of the contrasts generated by small Si crystallites in a very high density. After longer annealing time (Figure 1(b)), the small Si crystallites grow in size but may take overall less volume fraction due to the Ostwald ripening process. Therefore, it explains the reduction in crystallinity of Si discovered from 210s annealed sample to 270s annealed sample by Raman. However, such a reduction in Si crystallinity was not observed in nitrogen annealed SRSO films, this indicates that samples annealed in the forming gas environment follow a different crystallization mechanism and hydrogen must play a decisive role during the Si crystallization at the initial stage.

  • 16.
    Alvebratt, Caroline
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Cheung, Ocean
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Bergström, Christel A. S.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    A Modified In Situ Method to Determine Release from a Complex Drug Carrier in Particle-Rich Suspensions2018Ingår i: AAPS PharmSciTech, ISSN 1530-9932, E-ISSN 1530-9932, Vol. 19, nr 7, s. 2859-2865Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Effective and compound-sparing methods to evaluate promising drug delivery systems are a prerequisite for successful selection of formulations in early development stages. The aim of the study was to develop a small-scale in situ method to determine drug release and supersaturation in highly concentrated suspensions of enabling formulations. Mesoporous magnesium carbonate (MMC), which delivers the drug in an amorphous form, was selected as a drug carrier. Five model compounds were loaded into the MMC at a 1:10 ratio using a solvent evaporation technique. The μDiss Profiler was used to study the drug release from MMC in fasted-state simulated intestinal fluid. To avoid extensive light scattering previously seen in particle-rich suspensions in the μDiss Profiler, an in-house-designed protective nylon filter was placed on the in situ UV probes. Three types of release experiments were conducted for each compound: micronized crystalline drug with MMC present, drug-loaded MMC, and drug-loaded MMC with 0.01% w/w hydroxypropyl methyl cellulose. The nylon filters effectively diminished interference with the UV absorption; however, the release profiles obtained were heavily compound dependent. For one of the compounds, changes in the UV spectra were detected during the release from the MMC, and these were consistent with degradation of the compound. To conclude, the addition of protective nylon filters to the probes of the μDiss Profiler is a useful contribution to the method, making evaluations of particle-rich suspensions feasible. The method is a valuable addition to the current ones, allowing for fast and effective evaluation of advanced drug delivery systems.

  • 17.
    Alvebratt, Caroline
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Denning, T.
    Prestidge, Cliff
    Bergström, Christel
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Advanced methodologies to study in vitro digestion of a lipid-loaded mesoporous drug carrier2019Ingår i: Preclinical Form and Formulation for Drug Discovery, Gordon Research Conference 2019, 2019Konferensbidrag (Refereegranskat)
  • 18.
    Alvebratt, Caroline
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Petersson, E.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Bergström, Christel
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Dissolution studies of solid formulations - Applicability of µDiss inmonitoring supersaturation, nucleation and crystallization behavior; Casestudy: Carrier-based formulation.2016Ingår i: pION Fiber Optic Advanced Training Course. Uppsala, June 14-15, 2016., 2016Konferensbidrag (Refereegranskat)
  • 19.
    Alvebratt, Caroline
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Petersson, Erik
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bergström, Christel
    A small scale method to determine release rate from complex carrier-mediated systems2016Ingår i: Emerging Technologies in Drug Discovery and Development. Zhuhai, August 23-26, 2016., 2016Konferensbidrag (Refereegranskat)
  • 20.
    Alvebratt, Caroline
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Bergström, Christel
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
    A new method that enables in situ measurement of drug release from complex carrier-mediated systems2017Ingår i: 6th FIP Pharmaceutical Sciences World Congress2017., 2017Konferensbidrag (Refereegranskat)
  • 21.
    Amorim, Rodrigo G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Scheicher, Ralph H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Silicene as a new potential DNA sequencing device2015Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, nr 15, artikel-id 154002Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicene, a hexagonal buckled 2D allotrope of silicon, shows potential as a platform for numerous new applications, and may allow for easier integration with existing silicon-based microelectronics than graphene. Here, we show that silicene could function as an electrical DNA sequencing device. We investigated the stability of this novel nano-bio system, its electronic properties and the pronounced effects on the transverse electronic transport, i.e., changes in the transmission and the conductance caused by adsorption of each nucleobase, explored by us through the non-equilibrium Green's function method. Intriguingly, despite the relatively weak interaction between nucleobases and silicene, significant changes in the transmittance at zero bias are predicted by us, in particular for the two nucleobases cytosine and guanine. Our findings suggest that silicene could be utilized as an integrated-circuit biosensor as part of a lab-on-a-chip device for DNA sequencing.

  • 22.
    Andersson, Mikael Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Industriell teknik. Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.
    Nanoparticle Magnetism: Superspin Glasses2019Ingår i: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 19, nr 8, s. 4903-4910Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article discusses the magnetic super-phase, which occurs in strongly interacting magnetic nanoparticle systems. The phase is a nanoparticle analog to the atomic magnetic spin glass phase and is therefore called a superspin glass. Experimental data for a dense maghemite nanoparticle compact is presented and it is shown that this system forms a superspin glass phase by undergoing a second order phase transition. Below its transition temperature the system exhibits non-equilibrium dynamical properties similar to those of atomic spin glasses. It was shown that it is possible to tune the transition temperature by choosing the size of the particles used to make the compact. By mixing two sizes of particles (9 and 11.5 nm) and making compacts of different relative concentration of these sizes it was shown that it is the average dipolar interaction which determines the transition temperature.

  • 23.
    Andersson, Mikael Svante
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mathieu, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Lee, Su Seong
    The Nanos, Inst Bioengn & Nanotechnol, Singapore 138669, Singapore..
    Normile, Peter S.
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
    Singh, Gurvinder
    Norwegian Univ Sci & Technol, Dept Mat Sci & Engn, N-7491 Trondheim, Norway..
    Nordblad, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Angel De Toro, Jose
    Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
    Size-dependent surface effects in maghemite nanoparticles and its impact on interparticle interactions in dense assemblies2015Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, nr 47, artikel-id 475703Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The question of the dominant interparticle magnetic interaction type in random closely packed assemblies of different diameter (6.2-11.5 nm) bare maghemite nanoparticles (NPs) is addressed. Single-particle magnetic properties such as particle anisotropy and exchange bias field are first of all studied in dilute (reference) systems of these same NPs, where interparticle interactions are neglible. Substantial surface spin disorder is revealed in all particles except the smallest, viz. for diameters d = 8-11.5 nm but not for d = 6.2-6.3 nm. X-ray diffraction analysis points to a crystallographic origin of this effect. The study of closely packed assemblies of the d >= 8 nm particles observes collective (superspin) freezing that clearly appears to be governed by interparticle dipole interactions. However, the dense assemblies of the smallest particles exhibit freezing temperatures that are higher than expected from a simple (dipole) extrapolation of the corresponding temperatures found in the d >= 8 nm assemblies. It is suggested that the nature of the dominant interparticle interaction in these smaller particle assemblies is superexchange, whereby the lack of significant surface spin disorder allows this mechanism to become important at the level of interacting superspins.

  • 24. Angel Nino, Miguel
    et al.
    Kowalik, Iwona Agnieszka
    Jesus Luque, Francisco
    Arvanitis, Dimitri
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik V. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Miranda, Rodolfo
    Jose de Miguel, Juan
    Enantiospecific Spin Polarization of Electrons Photoemitted Through Layers of Homochiral Organic Molecules2014Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 26, nr 44, s. 7474-7479Artikel i tidskrift (Refereegranskat)
  • 25.
    Antila, Liisa J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ghamgosar, Pedram
    Maji, Somnath
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Tian, Haining
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Dynamics and Photochemical H-2 Evolution of Dye-NiO Photocathodes with a Biomimetic FeFe-Catalyst2016Ingår i: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 1, nr 6, s. 1106-1111Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mesoporous NiO films were cosensitized with a coumarin 343 dye and a proton reduction catalyst of the [Fe-2(CO)(6)(bdt)] (bdt = benzene-1,2-dithiolate) family. Femtosecond ultraviolet visible transient absorption experiments directly demonstrated subpicosecond hole injection into NiO from excited dyes followed by rapid (t(50%) similar to 6 ps) reduction of the catalyst on the surface with similar to 70% yield. The reduced catalyst was long-lived (2 mu s to 20 ms), which may allow protonation and a second reduction step of the catalyst to occur. A photo electrochemical device based on this photocathode produced H-2 with a Faradaic efficiency of similar to 50%. Fourier transform infrared spectroscopy and gas chromatography experiments demonstrated that the observed device deterioration with time was mainly due to catalyst degradation and desorption from the NiO surface. The insights gained from these mechanistic studies, regarding development of dye-catalyst cosensitized photocathodes, are discussed.

  • 26.
    Anttila-Eriksson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Electrical Characterizationon Commercially Available Chemical Vapor Deposition (CVD) Graphene2016Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Field-effect transistors (FET) based on graphene as channel has extraordinaryproperties in terms of charge mobility, charge carrier density etc. However, there aremany challenges to graphene based FET due to the fact graphene is a monolayer ofatoms in 2-dimentional space that is strongly influenced by the operating conditions.One issue is that the Dirac point, or K-point, shifts to higher gate voltage whengraphene is exposed to atmosphere. In this study graphene field-effect transistors(GFET) based on commercially available CVD graphene are electrically characterizedthrough field effect gated measurements. The Dirac point is initially unobservable andlocated at higher gate voltages (>+42 V), indicating high p-doping in graphene.Different treatments are tried to enhance the properties of GFET devices, such astransconductance, mobility and a decrease of the Dirac point to lower voltages, thatincludes current annealing, vacuum annealing, hot plate annealing, ionized water bathand UV-ozone cleaning. Vacuum annealing and annealing on a hot plate affect thegated response; they might have decreased the overall p-doping, but also introducedDirac points and non-linear features. These are thought to be explained by localp-doping of the graphene under the electrodes. Thus the Dirac point of CVDgraphene is still at higher gate voltages. Finally, the charge carrier mobility decreasedin all treatments except current – and hot plate annealing, and it is also observed that charge carrier mobilities after fabrication are lower than the manufacturer estimatesfor raw graphene on SiO2/Si substrate.

  • 27. Apell, S. P.
    et al.
    Hanson, G. W.
    Hägglund, Carl
    epartment of Chemical Engineering, Stanford University, USA.
    High optical absorption in grapheneManuskript (preprint) (Övrigt vetenskapligt)
  • 28.
    Araujo, Rafael B.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Banerjee, Amitava
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Panigrahi, Puspamitra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Hindustan Univ, Ctr Clean Energy & Nanoconvergence, Madras, Tamil Nadu, India.
    Yang, Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Sjödin, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Araujo, C. Moyses
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol KTH, Dept Mat, Appl Mat Phys, S-10044 Stockholm, Sweden.; Royal Inst Technol KTH, Dept Engn, S-10044 Stockholm, Sweden.
    Assessing Electrochemical Properties of Polypyridine and Polythiophene for Prospective Application in Sustainable Organic Batteries2017Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, nr 4, s. 3307-3314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Conducting polymers are being considered promising candidates for sustainable organic batteries mainly due to their fast electron transport properties and high recyclability. In this work, key properties of polythiophene and polypyridine have been assessed through a combined theoretical and experimental study focusing on such applications. A theoretical protocol has been developed to calculate redox potentials in solution within the framework of the density functional theory and using continuous solvation models. Here, the evolution of the electrochemical properties of solvated oligomers as a function of the length of the chain is analyzed and then the polymer properties are estimated via linear regressions using ordinary least square. The predicted values were verified against our electrochemical experiments. This protocol can now be employed to screen a large database of compounds in order to identify organic electrodes with superior properties.

  • 29.
    Araujo, Rafael B.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Banerjee, Amitava
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Panigrahi, Puspamitra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Hindustan Univ, Ctr Clean Energy & Nanoconvergence, Chennai, Tamil Nadu, India.
    Yang, Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Sjödin, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Araujo, C. Moyses
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    Designing strategies to tune reduction potential of organic molecules for sustainable high capacity batteries application2017Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 9, s. 4430-4454Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Organic compounds evolve as a promising alternative to the currently used inorganic materials in rechargeable batteries due to their low-cost, environmentally friendliness and flexibility. One of the strategies to reach acceptable energy densities and to deal with the high solubility of known organic compounds is to combine small redox active molecules, acting as capacity carrying centres, with conducting polymers. Following this strategy, it is important to achieve redox matching between the chosen molecule and the polymer backbone. Here, a synergetic approach combining theory and experiment has been employed to investigate this strategy. The framework of density functional theory connected with the reaction field method has been applied to predict the formal potential of 137 molecules and identify promising candidates for the referent application. The effects of including different ring types, e.g. fused rings or bonded rings, heteroatoms, [small pi] bonds, as well as carboxyl groups on the formal potential, has been rationalized. Finally, we have identified a number of molecules with acceptable theoretical capacities that show redox matching with thiophene-based conducting polymers which, hence, are suggested as pendent groups for the development of conducting redox polymer based electrode materials.

  • 30. Aroutiouinian, V. M.
    et al.
    Mkhitaryan, Z. H.
    Shatveryan, A. A.
    Ghulinyan, M.
    Pavesi, L.
    Granqvist, C.-G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kish, L.-B.
    Noise Spectroscopy of Gas Sensors2007Ingår i: Conference on Nanoelectronic Devices for Defence & Security (Nano-DDS), 2007, s. 69-Konferensbidrag (Refereegranskat)
  • 31.
    Arvizu, Miguel A
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Rejuvenation of degraded electrochromic MoO3 thin films made by DC magnetron sputtering: Preliminary results2016Ingår i: Journal of Physics: Conference Series, Institute of Physics Publishing (IOPP), 2016, Vol. 764, artikel-id 012009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Molybdenum oxide thin films were deposited by reactive DC magnetron sputtering and were subjected to voltammetric cycling in an electrolyte comprised of lithium perchlorate in propylene carbonate. The films were heavily degraded during 20 voltammetric cycles in an extended voltage range. The films were subsequently rejuvenated by use of potentiostatic treatments under different voltages during 20 hours. Optical changes were recorded during the electrochemical degradation and ensuing rejuvenation.

  • 32.
    Arvizu, Miguel A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Electrochromism in DC sputtered W1-yMoyO3 thin films2015Ingår i: INERA Conference 2015: Light in Nanoscience and Nanotechnolog (LNN2015) / [ed] Nesheva, D; Chamati, H; Genova, J; Gesheva, K; Ivanova, T; Szekeres, A, Institute of Physics (IOP), 2015, artikel-id 012005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Electrochromic (EC) properties of tungsten–molybdenum oxide (W1–yMoyO3) thin films were investigated. The films were deposited on indium tin oxide covered glass by reactive DC sputtering from tungsten and molybdenum targets. Elemental compositions of the W1–yMoyO3 films were determined by Rutherford back scattering. Voltammetric cycling was performed in an electrolyte of 1 M LiClO4 in propylene carbonate. The increase in molybdenum content in the EC films caused both a shift towards higher energies and a quenching of the value of the maximum of the coloration band, as compared with WO3 EC films. Durability was also diminished for W1–yMoyO3 EC films.

  • 33. Asano, Kohta
    et al.
    Westerwaal, Ruud J.
    Anastasopol, Anca
    Mooij, Lennard P. A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Boelsma, Christiaan
    Ngene, Peter
    Schreuders, Herman
    Eijt, Stephan W. H.
    Dam, Bernard
    Destabilization of Mg Hydride by Self-Organized Nanoclusters in the Immiscible Mg-Ti System2015Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, nr 22, s. 12157-12164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mg is an attractive hydrogen storage material not only because of its high gravimetric and volumetric hydrogen capacities but also because of it low material costs. However, the hydride of MgH2 is too stable to release hydrogen under moderate conditions. We demonstrate that the formation of nanometer-sized clusters of Mg reduces the stability of MgH2 by the interface energy effect in the immiscible Mg-Ti system. Ti-rich MgxTi1-x (x < 0.5) thin films deposited by magnetron sputtering have a hexagonal close packed (HCP) structure, which forms a face-centered cubic (FCC) hydride phase upon hydrogenation. Positron Doppler broadening depth profiling demonstrates that after hydrogenation, nanometer-sized MgH2 clusters are formed which are coherently embedded in an FCC TiH2 matrix. The P (pressure)-T (optical transmission) isotherms measured by hydrogenography show that these MgH2 clusters are destabilized. This indicates that the formation of nanometer-sized Mg allows for the development of a lightweight and cheap hydrogen storage material with a lower desorption temperature.

  • 34.
    Asfaw, Habtom
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuskript (preprint) (Övrigt vetenskapligt)
  • 35.
    Asper, M.
    et al.
    Charles River Biopharmaceut Serv GmbH, D-51105 Cologne, Germany..
    Hanrieder, T.
    Charles River Biopharmaceut Serv GmbH, D-51105 Cologne, Germany..
    Quellmalz, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Mihranyan, Albert
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Removal of xenotropic murine leukemia virus by nanocellulose based filter paper2015Ingår i: Biologicals (Print), ISSN 1045-1056, E-ISSN 1095-8320, Vol. 43, nr 6, s. 452-456Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The removal of xenotrpic murine leukemia virus (xMuLV) by size-exclusion filter paper composed of 100% naturally derived cellulose was validated. The filter paper was produced using cellulose nanofibers derived from Cladophora sp. algae. The filter paper was characterized using atomic force microscopy, scanning electron microscopy, helium pycnometry, and model tracer (100 nm latex beads and 50 nm gold nanoparticles) retention tests. Following the filtration of xMuLV spiked solutions, LRV >= 5.25 log(10) TCID50 was observed, as limited by the virus titre in the feed solution and sensitivity of the tissue infectivity test. The results of the validation study suggest that the nanocellulose filter paper is useful for removal of endogenous rodent retroviruses and retrovirus-like particles during the production of recombinant proteins.

  • 36. Atluri, Rambabu
    et al.
    Iqbal, Muhammad Naeem
    Bacsik, Zoltan
    Hedin, Niklas
    Villaescusa, Luis Angel
    Garcia-Bennett, Alfonso E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Self-assembly mechanism of folate-templated mesoporous silica.2013Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, nr 38, s. 12003-12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method to form ordered mesoporous silica based on the use of folate supramolecular templates has been developed. Evidence based on in situ small-angle X-ray scattering (SAXS), electron microscopy, infrared spectroscopy, and in situ conductivity measurements are used to investigate the organic-inorganic interactions and synthesis mechanism. The behavior of folate molecules in solution differs distinctively from that of surfactants commonly used for the preparation of ordered mesoporous silica phases, notably with the absence of a critical micellar concentration. In situ SAXS studies reveal fluctuations in X-ray scattering intensities consistent with the condensation of the silica precursor surrounding the folate template and the growth of the silica mesostructure in the initial stages. High-angle X-ray diffraction shows that the folate template is well-ordered within the pores even after a few minutes of synthesis. Direct structural data for the self-assembly of folates into chiral tetramers within the pores of mesoporous silica provide evidence for the in register stacking of folate tetramers, resulting in a chiral surface of rotated tetramers, with a rotation angle of 30°. Additionally, the self-assembled folates within pores were capable of adsorbing a considerable amount of CO2 gas through the cavity space of the tetramers. The study demonstrates the validity of using a naturally occurring template to produce relevant and functional mesoporous materials.

  • 37.
    Barros, Michael Taynnan
    et al.
    TSSG, Waterford Inst Technol, Waterford, Ireland.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Set point regulation of astrocyte intracellular Ca2+ signalling2017Ingår i: Proceedings / 2017 IEEE 17Th International Conference On Nanotechnology (IEEE-NANO), 2017, s. 315-320Konferensbidrag (Refereegranskat)
    Abstract [en]

    Neurodegenerative diseases are the current centre of attention in medicine due to their increased physiological and psychological burden on the ageing society and in the other hand the lack of efficient treatment to them. In parallel, nanotechnology opens possibilities to study neurodegeneration in the molecular level and uncover cellular properties at the nanoscale that possibly allow disease control using novel system biology methods. The communication between neurons and astrocytes explains how a failure in their communication impact neuronal activity, and how the intracellular Ca2+ signalling of astrocytes can interfere in the synaptic quality. This paper presents a theoretical investigation of a feed forward and feedback control technique to regulate the quantity of IP3 that determines the concentration of Ca2+ emitted from intracellular signalling. The analysis of the control model showed that the quantity of Ca2+ signalling can be stabilised at a desired level. A potential application is to facilitate the Ca2+ concentration around this desired level to maintain cellular homoeostasis for longer periods of time, which can lead to a technology for preventing neurodegenerative diseases. The proposed approach can result in novel solutions for both nanobiology and nanomedicine development, where synthetic biology can be used to program the control functionality into the cells. Other ways of implementing such technology are also explored, including nanoparticles, implantable devices and molecular communications.

  • 38.
    Baruah, Sunandan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Jaisai, Mayuree
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Pathumthani, Thailand.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Pathumthani, Thailand, and Sultan Qaboos University, Muscat, Sultanate of Oman.
    Development of a visible light active photocatalytic portable water purification unit using ZnO nanorods2012Ingår i: Catalysis Science & Technology, ISSN 2044-4753, Vol. 2, nr 5, s. 918-921Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A ZnO nanorods based water purification unit was designed which operates with solar energy as the source of activation. The purifier was tested on two model bacteria Escherichia coli and Staphylococcus aureus with concentration as high as 10(10) colony forming units (CFU) per litre, which is about 10(5) times higher than the bacterial concentration in tap water. Up to 99% (0.99 x 10(10) CFU L-1) removal of viable bacterial cells was achieved under sunlight activation.

  • 39.
    Basu, Alex
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ion-Crosslinked Nanocellulose Hydrogels for Advanced Wound Care Applications2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A current trend in the field of wound care is the development of wound healing materials that are designed to address specific types of wounds or underlying pathologies to achieve improved healing. At the same time, there is a societal drive to replace synthetic materials with renewable alternatives. The work presented in this thesis was therefore carried out to investigate the use of wood nanocellulose, produced from the world’s most abundant biopolymer, cellulose, in advanced wound care applications.

    Wood-based nanofibrillated cellulose (NFC) was chemically functionalized and crosslinked using calcium to obtain a self-standing hydrogel. The NFC hydrogel was evaluated in terms of its physicochemical properties, biocompatibility, blood interactions, bacterial interactions, in vivo wound healing ability and, finally, as a protein carrier. Parallel with the assessment of the NFC hydrogel, modified versions of the material were tested to investigate the tunability of the above-mentioned characteristics.

    The ability of the hydrogel to maintain a moist wound bed was demonstrated. Evaluation of the biocompatibility showed that the material was cytocompatible and did not trigger inflammatory mechanisms. Furthermore, the NFC hydrogel supported cell proliferation, and was shown to possess hemostatic properties. It was also discovered that the material had a slight bacteriostatic effect and the ability to act as a barrier against bacteria. When tested in vivo, the hydrogel was found to significantly improve wound healing.

    Modifications through the incorporation of additives to the hydrogel matrix, as well as exchange of the crosslinking ion, were shown to influence the biological response to the material. Moreover, the results presented here demonstrate the possibility of using the NFC hydrogel as a protein carrier; the easily adjustable charge property being identified as a central parameter for manipulation to regulate the release profile.

    In conclusion, this work has demonstrated the extensive wound healing ability of the calcium-crosslinked NFC hydrogel, and represents an important milestone in the research on NFC towards advanced wound care applications. It is expected that the easily modifiable nature of the material can be exploited to further develop the NFC hydrogel to suit the treatment needs for a broad range of wound types.

    Delarbeten
    1. On the use of ion-crosslinked nanocellulose hydrogels for wound healing solutions: Physicochemical properties and application-oriented biocompatibility studies
    Öppna denna publikation i ny flik eller fönster >>On the use of ion-crosslinked nanocellulose hydrogels for wound healing solutions: Physicochemical properties and application-oriented biocompatibility studies
    Visa övriga...
    2017 (Engelska)Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 174, s. 299-308Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Calcium ion-crosslinked nanofibrillated cellulose (NFC) hydrogels were investigated as potential materials for wound healing dressings. The physicochemical properties of the hydrogels were examined by rheology and water retention tests. Skin cells and monocytes were selected for application-oriented bio-compatibility studies. The NFC hydrogels presented entangled fibrous networks and solid-like behavior. Water retention tests showed the material's potential to maintain a suitable moist environment for different type of wounds. The hydrogels did not affect dermal fibroblasts monolayer cultures upon directcontact, as cell monolayers remained intact after application, incubation and removal of the materials. Inflammatory response studies with blood-derived mononuclear cells revealed the inert nature of the hydrogels in terms of cytokine secretion and reactive oxygen species production. Results highlight the great potential of ion-crosslinked NFC hydrogels for the development of advanced wound dressings, where further functionalization of the material could lead to improved properties towards the healing of specific wound types.

    Nyckelord
    Nanofibrillated cellulose, Inflammation, Fibroblasts, Mononuclear cells
    Nationell ämneskategori
    Nanoteknik
    Forskningsämne
    Teknisk fysik med inriktning mot nanoteknologi och funktionella material
    Identifikatorer
    urn:nbn:se:uu:diva-332126 (URN)10.1016/j.carbpol.2017.06.073 (DOI)000407696800032 ()28821071 (PubMedID)
    Forskningsfinansiär
    Forskningsrådet Formas
    Tillgänglig från: 2017-10-24 Skapad: 2017-10-24 Senast uppdaterad: 2018-10-12Bibliografiskt granskad
    2. Hemocompatibility of Ca2+-Crosslinked Nanocellulose Hydrogels: Toward Efficient Management of Hemostasis
    Öppna denna publikation i ny flik eller fönster >>Hemocompatibility of Ca2+-Crosslinked Nanocellulose Hydrogels: Toward Efficient Management of Hemostasis
    2017 (Engelska)Ingår i: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 17, nr 11, artikel-id 1700236Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The present work investigates Ca2+-crosslinked nanofibrillated cellulose hydrogels as potential hemostatic wound dressings by studying core interactions between the materials and a central component of wounds and wound healing—the blood. Hydrogels of wood-derived anionic nanofibrillated cellulose (NFC) and NFC hydrogels that incorporate kaolin or collagen are studied in an in vitro whole blood model and with platelet-free plasma assays. The evaluation of thrombin and factor XIIa formation, platelet reduction, and the release of activated complement system proteins, shows that the NFC hydrogel efficiently triggered blood coagulation, with a rapid onset of clot formation, while displaying basal complement system activation. By using the NFC hydrogel as a carrier of kaolin, the onset of hemostasis is further boosted, while the NFC hydrogel containing collagen exhibits blood activating properties comparable to the anionic NFC hydrogel. The herein studied NFC hydrogels demonstrate great potential for being part of advanced wound healing dressings that can be tuned to target certain wounds (e.g., strongly hemorrhaging ones) or specific phases of the wound healing process for optimal wound management.

    Nyckelord
    biocompatibility, blood coagulation, complement system, nanofibrillated cellulose, wound dressing
    Nationell ämneskategori
    Nanoteknik
    Forskningsämne
    Teknisk fysik med inriktning mot nanoteknologi och funktionella material
    Identifikatorer
    urn:nbn:se:uu:diva-332127 (URN)10.1002/mabi.201700236 (DOI)000415130800015 ()28941135 (PubMedID)
    Forskningsfinansiär
    Forskningsrådet Formas
    Tillgänglig från: 2017-10-24 Skapad: 2017-10-24 Senast uppdaterad: 2018-10-12Bibliografiskt granskad
    3. Ion-crosslinked wood-derived nanocellulose hydrogels with tunable antibacterial properties: Candidate materials for advanced wound care applications
    Öppna denna publikation i ny flik eller fönster >>Ion-crosslinked wood-derived nanocellulose hydrogels with tunable antibacterial properties: Candidate materials for advanced wound care applications
    Visa övriga...
    2018 (Engelska)Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 181, s. 345-350Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Development of advanced dressings with antimicrobial properties for the treatment of infected wounds is an important approach in the fight against evolution of antibiotic resistant bacterial strains. Herein, the effects of ion-crosslinked nanocellulose hydrogels on bacteria commonly found in infected wounds were investigated in vitro. By using divalent calcium or copper ions as crosslinking agents, different antibacterial properties against the bacterial strains Staphylococcus epidermidis and Pseudomonas aeruginosa were obtained. Calcium crosslinked hydrogels were found to retard S. epidermidis growth (up to 266% increase in lag time, 36% increase in doubling time) and inhibited P. aeruginosa biofilm formation, while copper crosslinked hydrogels prevented S. epidermidis growth and were bacteriostatic towards P. aeruginosa (49% increase in lag time, 78% increase in doubling time). The wound dressing candidates furthermore displayed barrier properties towards both S. epidermidis and P. aeruginosa, hence making them interesting for further development of advanced wound dressings with tunable antibacterial properties.

    Nyckelord
    Nanofibrillated cellulose, Biofilm, Wound dressing, Infected wound
    Nationell ämneskategori
    Nanoteknik
    Forskningsämne
    Teknisk fysik med inriktning mot nanoteknologi och funktionella material
    Identifikatorer
    urn:nbn:se:uu:diva-333382 (URN)10.1016/j.carbpol.2017.10.085 (DOI)000418661000041 ()29253982 (PubMedID)
    Forskningsfinansiär
    Forskningsrådet Formas
    Tillgänglig från: 2017-11-13 Skapad: 2017-11-13 Senast uppdaterad: 2018-10-12Bibliografiskt granskad
    4. In vitro and in vivo evaluation of the wound healing properties of nanofibrillated cellulose hydrogels
    Öppna denna publikation i ny flik eller fönster >>In vitro and in vivo evaluation of the wound healing properties of nanofibrillated cellulose hydrogels
    (Engelska)Ingår i: Artikel i tidskrift (Refereegranskat) Submitted
    Nationell ämneskategori
    Nanoteknik
    Forskningsämne
    Teknisk fysik med inriktning mot nanoteknologi och funktionella material
    Identifikatorer
    urn:nbn:se:uu:diva-362724 (URN)
    Tillgänglig från: 2018-10-09 Skapad: 2018-10-09 Senast uppdaterad: 2018-10-12
    5. Towards Tunable Protein-Carrier Wound Dressings Based on Nanocellulose Hydrogels Crosslinked with Calcium Ions
    Öppna denna publikation i ny flik eller fönster >>Towards Tunable Protein-Carrier Wound Dressings Based on Nanocellulose Hydrogels Crosslinked with Calcium Ions
    2018 (Engelska)Ingår i: Nanomaterials, E-ISSN 2079-4991, Vol. 8, nr 7, artikel-id 550Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    A Ca2+-crosslinked wood-based nanofibrillated cellulose (NFC) hydrogel was investigated to build knowledge toward the use of nanocellulose for topical drug delivery applications in a chronic wound healing context. Proteins of varying size and isoelectric point were loaded into the hydrogel in a simple soaking procedure. The release of the proteins from the hydrogel was monitored and kinetics determining parameters of the release processes were assessed. The integrity of the hydrogel and proteins were also studied. The results showed that electrostatic interactions between the proteins and the negatively-charged NFC hydrogel structure played a central role in the loading process. The release of the proteins were governed by Fickian diffusion. An increased protein size, as well as a positive protein charge facilitated a slower and more sustained release process from the hydrogel matrix. At the same time, the positively-charged protein was shown to increase the post-loading hydrogel strength. Released proteins maintained structural stability and activity, thus indicating that the Ca2+-crosslinked NFC hydrogel could function as a carrier of therapeutic proteins without compromising protein function. It is foreseen that, by utilizing tunable charge properties of the NFC hydrogel, release profiles can be tailored to meet very specific treatment needs.

    Ort, förlag, år, upplaga, sidor
    MDPI, 2018
    Nyckelord
    nanofibrillated cellulose, ion-crosslinked, drug delivery, wound healing, chronic wounds
    Nationell ämneskategori
    Nanoteknik
    Forskningsämne
    Teknisk fysik med inriktning mot nanoteknologi och funktionella material
    Identifikatorer
    urn:nbn:se:uu:diva-362722 (URN)10.3390/nano8070550 (DOI)000442523100101 ()30036970 (PubMedID)
    Forskningsfinansiär
    Forskningsrådet Formas, 942-2015-475
    Tillgänglig från: 2018-10-09 Skapad: 2018-10-09 Senast uppdaterad: 2018-10-30Bibliografiskt granskad
  • 40.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Celma, Gunta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    In vitro and in vivo evaluation of the wound healing properties of nanofibrillated cellulose hydrogelsIngår i: Artikel i tidskrift (Refereegranskat)
  • 41.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Celma, Gunta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ion-crosslinked nanocellulose hydrogels promote wound healing in vitro and in vivo2019Ingår i: Scandinavian Society for Biomaterials Conference 2019 / [ed] Scandinavian Society for Biomaterials, 2019Konferensbidrag (Refereegranskat)
  • 42.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ion-crosslinked nanocellulose hydrogels for biomedical applications2015Konferensbidrag (Refereegranskat)
  • 43.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nanocellulose hydrogels as candidates for advanced wound healing solutions2018Konferensbidrag (Refereegranskat)
  • 44.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nanocellulose hydrogels for topical wound care applications2016Konferensbidrag (Övrigt vetenskapligt)
  • 45.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nanocellulose hydrogels for wound-healing applications2016Konferensbidrag (Refereegranskat)
  • 46.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nanocellulose hydrogels: preparation, characterization and cytotoxicity studies toward biomedical applications2016Konferensbidrag (Refereegranskat)
  • 47.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nanofibrillated cellulose hydrogels for wound healing solutions: the status quo and future prospects2015Ingår i: Uppsala Biomaterials Conference 2015, 2015Konferensbidrag (Refereegranskat)
  • 48.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Heitz, Karen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Welch, Ken
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ion-crosslinked wood-derived nanocellulose hydrogels with tunable antibacterial properties: Candidate materials for advanced wound care applications2018Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 181, s. 345-350Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Development of advanced dressings with antimicrobial properties for the treatment of infected wounds is an important approach in the fight against evolution of antibiotic resistant bacterial strains. Herein, the effects of ion-crosslinked nanocellulose hydrogels on bacteria commonly found in infected wounds were investigated in vitro. By using divalent calcium or copper ions as crosslinking agents, different antibacterial properties against the bacterial strains Staphylococcus epidermidis and Pseudomonas aeruginosa were obtained. Calcium crosslinked hydrogels were found to retard S. epidermidis growth (up to 266% increase in lag time, 36% increase in doubling time) and inhibited P. aeruginosa biofilm formation, while copper crosslinked hydrogels prevented S. epidermidis growth and were bacteriostatic towards P. aeruginosa (49% increase in lag time, 78% increase in doubling time). The wound dressing candidates furthermore displayed barrier properties towards both S. epidermidis and P. aeruginosa, hence making them interesting for further development of advanced wound dressings with tunable antibacterial properties.

  • 49.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Hong, Jaan
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Klinisk immunologi.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Hemocompatibility of Ca2+-Crosslinked Nanocellulose Hydrogels: Toward Efficient Management of Hemostasis2017Ingår i: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 17, nr 11, artikel-id 1700236Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present work investigates Ca2+-crosslinked nanofibrillated cellulose hydrogels as potential hemostatic wound dressings by studying core interactions between the materials and a central component of wounds and wound healing—the blood. Hydrogels of wood-derived anionic nanofibrillated cellulose (NFC) and NFC hydrogels that incorporate kaolin or collagen are studied in an in vitro whole blood model and with platelet-free plasma assays. The evaluation of thrombin and factor XIIa formation, platelet reduction, and the release of activated complement system proteins, shows that the NFC hydrogel efficiently triggered blood coagulation, with a rapid onset of clot formation, while displaying basal complement system activation. By using the NFC hydrogel as a carrier of kaolin, the onset of hemostasis is further boosted, while the NFC hydrogel containing collagen exhibits blood activating properties comparable to the anionic NFC hydrogel. The herein studied NFC hydrogels demonstrate great potential for being part of advanced wound healing dressings that can be tuned to target certain wounds (e.g., strongly hemorrhaging ones) or specific phases of the wound healing process for optimal wound management.

  • 50.
    Basu, Alex
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Hong, Jaan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Klinisk immunologi.
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ion-crosslinked nanocelluose hydrogels as potential hemostatic wound dressings2019Ingår i: Euromat 2019, 2019Konferensbidrag (Refereegranskat)
1234567 1 - 50 av 1061
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