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  • 1.
    Chajara, Khalil
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för biokemi och organisk kemi.
    Andersson, Claes-Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för biokemi och organisk kemi.
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrostrukturlaboratoriet, MSL. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Widenkvist, Erika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Grennberg, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för biokemi och organisk kemi.
    The reagent-free, microwave-assisted purification of carbon nanotubes2010Inngår i: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 34, nr 10, s. 2275-2280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed a microwave-assisted, reagent-free method for the efficient primary purification of MW and SW carbon nanotubes that is extremely fast compared to previously reported processes. The treatment dissociates and disperses non-nanotube carbon in an organic solvent to yield very pure carbon nanotubes within a few minutes of heating and a simple filtration, without the involvement of acidic/oxidative reagents. According to thermogravimetric analysis, Raman and IR spectroscopy, as well as scanning and transmission electron microscopy, the process yields pure nanotubes with a low degree of defects.

  • 2.
    Chen, Song
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Shi, Liyang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi. Hunan Univ, Coll Biol, Changsha 410082, Hunan, Peoples R China.
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Novel Fast-Setting Mineral Trioxide Aggregate: Its Formulation, Chemical-Physical Properties, and Cytocompatibility2018Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 24, s. 20334-20341Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the main drawbacks that limits the application of mineral trioxide aggregate (MTA) in dental field is its long setting time. Mineral trioxide aggregate with accelerated setting properties and excellent chemical-physical and biological properties is still required. In this study, an innovative mineral trioxide aggregate, which consists of calcium silicates, calcium aluminates, and zirconium oxide, was designed to obtain fast-setting property. The optimized formulation can achieve initial setting in 10 min and final setting in 15 min, which are much faster than commercial mineral trioxide aggregate. In addition, the optimized fast-setting MTA showed adequate radiopacity and good biocompatibility. The ion concentrations after storage in water for 1 day were 52.3 mg/L Ca, 67.7 mg/L Al, 48.8 mg/L Si, and 11.7 mg/L Mg. The hydration products of hardened cements were investigated by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared, showing the accelerated setting time was due to the formation of honeycomb-like calcium silicate hydrate gel. The novel MTA could be a promising material for dental applications.

  • 3. Dezelah, Charles L.
    et al.
    Niinisto, Jaakko
    Kukli, Kaupo
    Munnik, Frans
    Lu, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Ritala, Mikko
    Leskela, Markku
    Niinisto, Lauri
    The Atomic Layer Deposition of HfO2 and ZrO2 using Advanced Metallocene Precursors and H2O as the Oxygen Source2008Inngår i: Chemical Vapor Deposition, ISSN 0948-1907, E-ISSN 1521-3862, Vol. 14, nr 11-12, s. 358-365Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The atomic layer deposition (ALD) of HfO2 and ZrO2 thin films is investigated using (MeCp)(2)HfMe2, (MCp)(2)Hf(OMe)(Me), (MeCp)(2)ZrMe2, and (MeCp)(2)Zr(OMe)(Me) as the precursors at deposition temperatures between 300 and 500 degrees C, with water vapor as the oxygen Source. A self-limiting growth mechanism is confirmed at 350 degrees C for all the metal precursors examined. The processes provide nearly stoichiometric HfO2 and ZrO2 films with carbon and hydrogen concentrations below 0.5 and 1.0 at.-%, respectively, for representative samples. All films are polycrystalline as deposited, and possess a thin interfacial SiO2 layer. The capacitance-voltage (C-V) and Current density-voltage (I-V) behavior is reported and discussed for capacitor structures containing films from this study.

  • 4. Duenas, S.
    et al.
    Castan, H.
    Garcia, H.
    Bailon, L.
    Kukli, K.
    Lu, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Ritala, M.
    Leskelae, M.
    Selection of post-growth treatment parameters for atomic layer deposition of structurally disordered TiO2 thin films2008Inngår i: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 354, nr 2-9, s. 404-408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Routes to atomic layer-deposited TiO2 films With decreased leakage have been studied by using electrical characterization techniques. The combination of post-deposition annealing parameters, time and temperature, which provides measurable aluminum-titanium oxide-silicon structures - i.e., having capacitance-voltage curves which show accumulation behavior - are 625 degrees C, 10 min for p-type substrates, and 550 degrees C, 10 min for n-type substrates. The best annealing conditions for p-type substrates are 625 degrees C with the length extended to 30 min, which produces an interfacial state density of about 5-6 x 10(11) cm(-2) eV(-1), and disordered-induced gap state density below our experimental limits. We have also proved that a post-deposition annealing must be applied to TiO2/HfO2 and HfO2/TiO2/HfO2 stacked structures to obtain adequate measurability conditions.

  • 5. Gudmundsson, Valur
    et al.
    Hellström, Per-Erik
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Lu, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Östling, Mikael
    Fully Depleted UTB and Trigate N-Channel MOSFETs Featuring Low-Temperature PtSi Schottky-Barrier Contacts With Dopant Segregation2009Inngår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 30, nr 5, s. 541-543Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Schottky-barrier source/drain (SB-S/D) presents a promising solution to reducing parasitic resistance for device architectures such as fully depleted UTB, trigate, or FinFET. In this letter, a low-temperature process (<= 700 degrees C) with PtSi-based S/D is examined for the fabrication of n-type UTB and trigate FETs on SOI substrate (t(si) = 30 nm). Dopant segregation with As was used to achieve the n-type behavior at implantation doses of 1 (.) 10(15) and 5. 10(15) cm(-2). Similar results were found for UTB devices with both doses, but trigate devices with the larger dose exhibited higher on currents and smaller process variation than their lower dose counterparts.

  • 6. Kukli, Kaupo
    et al.
    Aarik, Jaan
    Aidla, Aleks
    Jogi, Indrek
    Arroval, Tonis
    Lu, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Sajavaara, Timo
    Laitinen, Mikko
    Kiisler, Alma-Asta
    Ritala, Mikko
    Leskela, Markku
    Peck, John
    Natwora, Jim
    Geary, Joan
    Spohn, Ronald
    Meiere, Scott
    Thompson, David M.
    Atomic layer deposition of Ru films from bis(2,5-dimethylpyrrolyl)ruthenium and oxygen2012Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, nr 7, s. 2756-2763Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ru thin films were grown on hydrogen terminated Si, SiO2, Al2O3, HfO2, and TiO2 surfaces by atomic layer deposition from bis(2,5-dimethylpyrrolyl)ruthenium precursor and oxygen. The 4-20 nm thick films on these surfaces consisted of nanocrystalline hexagonal metallic ruthenium, regardless of the deposition temperature. At the lowest temperatures examined, 250-255 degrees C, the growth of the Ru films was favored on silicon, compared to the growth on Al2O3, TiO2 and HfO2. At higher temperatures the nucleation and growth of Ru became enhanced in particular on HfO2, compared to the process on silicon. At 320-325 degrees C, no growth occurred on Si-H and SiO2-covered silicon. Resistivity values down to 18 mu Omega.cm were obtained for ca. 10 nm thick Ru films. 

  • 7. Lu, Jun
    et al.
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Ostling, Mikael
    Hultman, Lars
    On Epitaxy of Ultrathin Ni1-xPtx Silicide Films on Si(001)2010Inngår i: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 13, nr 10, s. H360-H362Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Epitaxial Ni(Pt)Si2-y (y < 1) films readily grow upon thermal treatment of 2 nm thick Ni and Ni0.96Pt0.04 films deposited on Si(001). For annealing at 500 degrees C, the films are 5.4-5.6 nm thick with 61-70 mu cm in resistivity. At 750 degrees C, the epitaxial Ni(Pt)Si2-y films become 6.1-6.2 nm thick with a resistivity of 42-44 mu cm. Structural analysis reveals twins, facet wedges, and thickness inhomogeneities in the films grown at 500 degrees C. For higher temperature, an almost defect-free NiSi2-y film with a flat and sharp interface is formed. The presence of Pt makes the aforementioned imperfections more persistent.

  • 8.
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Calcium Phosphate Based Biomaterials for Bone Augmentation2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Basic (apatite-based) calcium phosphate cements (CPCs), and acidic (brushite and monetite-based) CPCs are used as bone replacement materials because of their bioactivity, mouldability and ability to harden in place. However, their application is limited by their inherent brittleness and difficulties related to their handling. The current thesis aimed to provide solutions to these limitations.

    To assess the baseline, the mechanical properties of two promising experimental and two commercially available apatite and brushite cements were investigated. The two experimental CPCs exhibited significantly higher mechanical strengths than the two commercially available ones, warranting further advancement of the former towards clinical use.

    The setting reaction of brushite cements was, for the first time, quantitatively studied in the first seconds and minutes, using synchrotron X-ray diffraction. The reaction was found to include a fast nucleation induction period (<9 s), nucleation (<18 s), brushite content increase and setting completion. The effect of the commonly used retardant citric acid – which usually also gives stronger brushite cements - was also evaluated, providing important information for further cement development.  

    To overcome complicated usage and short shelf life of acidic CPCs, a ready-to-use acidic CPC was developed by mixing a monocalcium phosphate monohydrate (MCPM) paste and a β-tricalcium phosphate (β-TCP) paste with suitable amounts of citric acid. The CPC showed adequate shelf life, good cohesion and mechanical performance.

    To mitigate against the brittle behavior of CPCs, i) poly(vinyl alcohol) fibres were used to reinforce apatite cements, significantly improving the apatite matrix’s toughness and resistance to cracking; ii) injectable, ready-to-use organic-inorganic composites with partly elastomeric compression behavior were designed based on silk fibroin hydrogels and acidic calcium phosphates, and their ability for antibiotic drug delivery was assessed. 

    In summary, insights into the functional properties of currently available CPCs as well as the setting process of brushite cements were gained and several new calcium phosphate-based formulations were developed to overcome some of the drawbacks of traditional CPCs. Further studies, in particular of the biological response, are needed to verify the potential of the developed materials for future use in the clinical setting. 

     

    Delarbeid
    1. Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements
    Åpne denne publikasjonen i ny fane eller vindu >>Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements
    Vise andre…
    2016 (engelsk)Inngår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 60, s. 617-627Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Calcium phosphate cements (CPCs) are widely used in bone repair. Currently there are two main types of CPCs, brushite and apatite. The aim of this project was to evaluate the mechanical properties of particularly promising experimental brushite and apatite formulations in comparison to commercially available brushite- and apatite-based cements (chronOS Inject and Norian® SRS®, respectively), and in particular evaluate the diametral tensile strength and biaxial flexural strength of these cements in both wet and dry conditions for the first time. The cements׳ porosity and their compressive, diametral tensile and biaxial flexural strength were tested in wet (or moist) and dry conditions. The surface morphology was characterized by scanning electron microscopy. Phase composition was assessed with X-ray diffraction. It was found that the novel experimental cements showed better mechanical properties than the commercially available cements, in all loading scenarios. The highest compressive strength (57.2±6.5 MPa before drying and 69.5±6.0 MPa after drying) was found for the experimental brushite cement. This cement also showed the highest wet diametral tensile strength (10.0±0.8 MPa) and wet biaxial flexural strength (30.7±1.8 MPa). It was also the cement that presented the lowest porosity (approx. 12%). The influence of water content was found to depend on cement type, with some cements showing higher mechanical properties after drying and some no difference after drying.

    Emneord
    Calcium phosphate cement; Brushite; Apatite; Compressive strength; Tensile strength; Flexural strength
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-284218 (URN)10.1016/j.jmbbm.2016.03.028 (DOI)000378969100055 ()27082025 (PubMedID)
    Forskningsfinansiär
    The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IG2011-2047Swedish Research Council, 621-2011-6258
    Tilgjengelig fra: 2016-04-15 Laget: 2016-04-15 Sist oppdatert: 2018-08-10bibliografisk kontrollert
    2. In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth
    Åpne denne publikasjonen i ny fane eller vindu >>In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth
    Vise andre…
    2017 (engelsk)Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 41, s. 36392-36399Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Brushite cements are fast self-setting materials that can be used as bone substitute materials. Although tracing their fast setting process is a challenge, it is important for the understanding of the same, which in turn is important for the material’s further development and use in the clinics. In this study, the setting rate, phase formation, and crystal growth of brushite cements were quantitatively studied by in situ synchrotron powder X-ray diffraction (SXRD) on a time scale of seconds. The influence of reactant ratios and a retardant (citric acid) on the setting reaction were analyzed. To complement the in situ investigations, scanning electron microscopy was carried out for ex situ morphological evolution of crystals. The initial reaction followed a four-step process, including a fast nucleation induction period, nucleation, crystal growth, and completion of the setting. The brushite crystal size grew up to the micro scale within 1 min, and the brushite content increased linearly after the nucleation until all monocalcium phosphate monohydrate (MCPM; Ca(H2PO4)2·H2O) had dissolved within minutes, followed by a slow increase until the end of the monitoring. By adjusting the MCPM to the β-tricalcium phosphate (β-TCP, β-Ca3(PO4)2) ratio in the starting powders, the brushite/monetite ratio in the cements could be modified. In the presence of citric acid, the formation of brushite nuclei was not significantly retarded, whereas the increase in brushite content and the growth of crystal size were effectively hindered. The amount of monetite also increased by adding citric acid. This is the first time that the brushite setting process has been characterized in the first seconds and minutes of the reaction by SXRD.

    Emneord
    synchrotron X-ray diffraction, setting reaction process, brushite cement, crystal size, citric acid, MCPM/β-TCP ratio
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot materialvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-330146 (URN)10.1021/acsami.7b10159 (DOI)000413503700092 ()
    Tilgjengelig fra: 2017-09-26 Laget: 2017-09-26 Sist oppdatert: 2018-08-10bibliografisk kontrollert
    3. A ready-to-use acidic calcium phosphate cement
    Åpne denne publikasjonen i ny fane eller vindu >>A ready-to-use acidic calcium phosphate cement
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Premixed calcium phosphate cements have been developed to simplify the usage of traditional calcium phosphate cements and reduce the influence of the setting reaction on the delivery process. However, difficulties in achieving a good cohesion, adequate shelf life and sufficient mechanical properties have so far impeded their use in clinical applications, especially for the more degradable acidic calcium phosphate cements.

    In this study, a brushite cement was developed from a series of ready-to-use calcium phosphate pastes. The brushite cement paste was formed via mixing of a monocalcium phosphate monohydrate (MCPM) paste and a β-tricalcium phosphate (β-TCP) paste with good injectability and adequate shelf life. The MCPM paste was based on a water-immiscible liquid with two surfactants and the β-TCP paste on a sodium hylauronate aqueous solution. The effect of citric acid as a retardant was assessed. Formulations with suitable amounts of citric acid showed good cohesion and mechanical performance with potential for future clinical applications.

    Emneord
    Ready-to-use, acidic calcium phosphate cement, brushite, cohesion, injectability, shelf life
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-356978 (URN)
    Tilgjengelig fra: 2018-08-09 Laget: 2018-08-09 Sist oppdatert: 2018-08-10
    4. The addition of poly(vinyl alcohol) fibres to apatitic calcium phosphate cement can improve its toughness
    Åpne denne publikasjonen i ny fane eller vindu >>The addition of poly(vinyl alcohol) fibres to apatitic calcium phosphate cement can improve its toughness
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Calcium phosphate cements, and in particular hydroxyapatite cements, have been widely investigated for use as bone void fillers due to their chemical similarity to bone and related osteoconductivity. However, they are brittle, which limits their use to non-load-bearing applications.

    The aim of the current study was to improve the toughness of hydroxyapatite cements through fibre reinforcement. The effect of the addition of hydrophilic, poly(vinyl-alcohol) (PVA) fibres to hydroxyapatite cement was evaluated in terms of mechanical properties, including compressive strength, diametral tensile strength and toughness (work of fracture), as well as setting time, phase composition and cement morphology. The fibre reinforcement enhanced the fracture resistance of the hydroxyapatite cement, but also simultaneously reduced the compressive strength and setting time of the cements. However, cement with 5 wt% of fibres (of powder component) could be considered a good compromise, with a compressive strength of 46.5 ± 4.6 MPa (compared to 62.3 ± 12.8 MPa of that without fibres), i.e. still much greater than that of human trabecular bone (0.1-14 MPa). A significantly higher diametral tensile strength (9.2 ± 0.4 MPa) was found for this cement compared to that without fibres (7.4 ± 1.5 MPa). The work of fracture increased four times to 9.1 ± 1.5 kJ/m2 in comparison to the pristine apatite. In summary, the hydroxyapatite cements could be reinforced by suitable amounts of PVA fibres, which resulted in enhancing the material’s structural integrity and ductility, and increased the material’s resistance to cracking.

    Emneord
    fibre reinforcement, apatite cement, poly(vinyl alcohol), composite, compressive strength, work of fracture, diametral tensile strength, toughness
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-356979 (URN)
    Tilgjengelig fra: 2018-08-09 Laget: 2018-08-09 Sist oppdatert: 2018-08-10
    5. Silk fibroin hydrogels induced and reinforced by acidic calcium phosphate – A simple way of producing injectable, bioactive and drug-loadable composites for biomedical applications
    Åpne denne publikasjonen i ny fane eller vindu >>Silk fibroin hydrogels induced and reinforced by acidic calcium phosphate – A simple way of producing injectable, bioactive and drug-loadable composites for biomedical applications
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    silk fibroin, acidic calcium phosphates, composites, hydrogels, mechanical strength, drug-loadable
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-356991 (URN)
    Tilgjengelig fra: 2018-08-10 Laget: 2018-08-10 Sist oppdatert: 2018-08-10
  • 9.
    Luo, Jun
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Ajaxon, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Ginebra, Maria Pau
    Research Centre in Biomedical Engineering, Biomaterials Division, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC).
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements2016Inngår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 60, s. 617-627Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Calcium phosphate cements (CPCs) are widely used in bone repair. Currently there are two main types of CPCs, brushite and apatite. The aim of this project was to evaluate the mechanical properties of particularly promising experimental brushite and apatite formulations in comparison to commercially available brushite- and apatite-based cements (chronOS Inject and Norian® SRS®, respectively), and in particular evaluate the diametral tensile strength and biaxial flexural strength of these cements in both wet and dry conditions for the first time. The cements׳ porosity and their compressive, diametral tensile and biaxial flexural strength were tested in wet (or moist) and dry conditions. The surface morphology was characterized by scanning electron microscopy. Phase composition was assessed with X-ray diffraction. It was found that the novel experimental cements showed better mechanical properties than the commercially available cements, in all loading scenarios. The highest compressive strength (57.2±6.5 MPa before drying and 69.5±6.0 MPa after drying) was found for the experimental brushite cement. This cement also showed the highest wet diametral tensile strength (10.0±0.8 MPa) and wet biaxial flexural strength (30.7±1.8 MPa). It was also the cement that presented the lowest porosity (approx. 12%). The influence of water content was found to depend on cement type, with some cements showing higher mechanical properties after drying and some no difference after drying.

  • 10.
    Luo, Jun
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    A ready-to-use acidic, brushite-forming calcium phosphate cement2018Inngår i: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 81, s. 304-314Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Premixed calcium phosphate cements have been developed to simplify the usage of traditional calcium phosphate cements and reduce the influence of the setting reaction on the delivery process. However, difficulties in achieving a good cohesion, adequate shelf life and sufficient mechanical properties have so far impeded their use in clinical applications, especially for the more degradable acidic calcium phosphate cements. In this study, a brushite cement was developed from a series of ready-to-use calcium phosphate pastes. The brushite cement paste was formed via mixing of a monocalcium phosphate monohydrate (MCPM) paste and a beta-tricalcium phosphate (beta-TCP) paste with good injectability and adequate shelf life. The MCPM paste was based on a water-immiscible liquid with two surfactants and the beta-Tcp paste on a sodium hyaluronate aqueous solution. The effect of citric acid as a retardant was assessed. Formulations with suitable amounts of citric acid showed good cohesion and mechanical performance with potential for future clinical applications. Statement of Significance Acidic calcium phosphate cements have attracted extensive attention as bone substitute materials due to their ability to resorb faster than basic calcium phosphate cements in vivo. However, traditionally, short working times and low mechanical strength have limited their clinical application. Premixed cements could simplify the clinical use as well as improve property reproducibility, but short shelf lives, low cohesion and low mechanical properties have restricted the development. In this study, an injectable ready-to-use two-phase system consisting of an MCPM paste and a beta-TCP paste was developed based on acidic cement. It shows good cohesion, compressive strength and adequate shelf life, which has the potential to be used in a dual chamber system for simplified and fast filling of bone defects in a minimally invasive manner. This will reduce surgery time, decrease the risk of contamination and ensure repeatable results.

  • 11.
    Luo, Jun
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Faivre, Julien
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    The Addition of Poly(Vinyl Alcohol) Fibers to Apatitic Calcium Phosphate Cement Can Improve Its Toughness2019Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 9, artikkel-id 1531Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Calcium phosphate cements, and in particular hydroxyapatite cements, have been widely investigated for use as bone void fillers due to their chemical similarity to bone and related osteoconductivity. However, they are brittle, which limits their use to non-load-bearing applications. The aim of the current study was to improve the toughness of hydroxyapatite cements through fiber reinforcement. The effect of the addition of hydrophilic, poly(vinyl-alcohol) (PVA) fibers to hydroxyapatite cement was evaluated in terms of mechanical properties, including compressive strength, diametral tensile strength and toughness (work of fracture), as well as setting time, phase composition and cement morphology. The fiber reinforcement enhanced the fracture resistance of the hydroxyapatite cement, but also simultaneously reduced the compressive strength and setting time of the cements. However, cement with 5 wt % of fibers (of the powder component) could be considered a good compromise, with a compressive strength of 46.5 +/- 4.6 MPa (compared to 62.3 +/- 12.8 MPa of that without fibers), i.e., still much greater than that of human trabecular bone (0.1-14 MPa). A significantly higher diametral tensile strength (9.2 +/- 0.4 MPa) was found for this cement compared to that without fibers (7.4 +/- 1.5 MPa). The work of fracture increased four times to 9.1 +/- 1.5 kJ/m(2) in comparison to the pristine apatite. In summary, the hydroxyapatite cements could be reinforced by suitable amounts of PVA fibers, which resulted in enhancing the material's structural integrity and ductility, and increased the material's resistance to cracking.

  • 12.
    Luo, Jun
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Martinez-Casado, Francisco Javier
    Max IV Laboratory, Lund University.
    Balmes, Olivier
    Max IV Laboratory, Lund University.
    Yang, Jiaojiao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Xia, Wei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth2017Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 41, s. 36392-36399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Brushite cements are fast self-setting materials that can be used as bone substitute materials. Although tracing their fast setting process is a challenge, it is important for the understanding of the same, which in turn is important for the material’s further development and use in the clinics. In this study, the setting rate, phase formation, and crystal growth of brushite cements were quantitatively studied by in situ synchrotron powder X-ray diffraction (SXRD) on a time scale of seconds. The influence of reactant ratios and a retardant (citric acid) on the setting reaction were analyzed. To complement the in situ investigations, scanning electron microscopy was carried out for ex situ morphological evolution of crystals. The initial reaction followed a four-step process, including a fast nucleation induction period, nucleation, crystal growth, and completion of the setting. The brushite crystal size grew up to the micro scale within 1 min, and the brushite content increased linearly after the nucleation until all monocalcium phosphate monohydrate (MCPM; Ca(H2PO4)2·H2O) had dissolved within minutes, followed by a slow increase until the end of the monitoring. By adjusting the MCPM to the β-tricalcium phosphate (β-TCP, β-Ca3(PO4)2) ratio in the starting powders, the brushite/monetite ratio in the cements could be modified. In the presence of citric acid, the formation of brushite nuclei was not significantly retarded, whereas the increase in brushite content and the growth of crystal size were effectively hindered. The amount of monetite also increased by adding citric acid. This is the first time that the brushite setting process has been characterized in the first seconds and minutes of the reaction by SXRD.

  • 13.
    Luo, Jun
    et al.
    Institute of Microelectronics of Chinese Academy of Sciences.
    Qiu, Zhijun
    Fudan University.
    Deng, Jian
    Institute of Microelectronics of Chinese Academy of Sciences.
    Zhao, Chao
    Institute of Microelectronics of Chinese Academy of Sciences.
    Li, Junfeng
    Institute of Microelectronics of Chinese Academy of Sciences.
    Wang, Wenwu
    Institute of Microelectronics of Chinese Academy of Sciences.
    Cheng, Dapeng
    Institute of Microelectronics of Chinese Academy of Sciences.
    Wu, Dongping
    Fudan University.
    Östling, Michael
    KTH.
    Ye, Tianchun
    Institute of Microelectronics of Chinese Academy of Sciences.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Variation of Schottky barrier height induced by dopant segregation monitored by contact resistivity measurements2013Konferansepaper (Annet vitenskapelig)
  • 14.
    Luo, Jun
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Qiu, Zhi-Jun
    Zhang, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Östling, Mikael
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Interaction of NiSi with dopants for metallic source/drain applications2010Inngår i: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 28, nr 1, s. C1I1-C1I11Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work has a focus on NiSi as a possible metallic contact for aggressively scaled complementary metal oxide semiconductor devices. As the bulk work function of NiSi lies close to the middle of Si bandgap, the Schottky barrier height (SBH) of NiSi is rather large for both electron ( ∼ 0.65 eV) and hole ( ∼ 0.45 eV). Different approaches have therefore been intensively investigated in the literature aiming at reducing the effective SBH: dopant segregation (DS), surface passivation (SP), and alloying, in order to improve the carrier injection into the conduction channel of a field-effect transistor. The present work explores DS using B and As for the NiSi/Si contact system. The effects of C and N implantation into Si substrate prior to the NiSi formation are examined, and it is found that the presence of C yields positive effects in helping reduce the effective SBH to 0.1–0.2 eV for both conduction polarities. A combined use of DS or SP with alloying could be considered for more effective control of effective SBH, but an examination of undesired compound formation and its probable consequences is necessary. Furthermore, an analysis of the metal silicides that have a small “intrinsic” SBH reveals that only a very small number of them are of practical interest as most of the silicides require either a high formation temperature or possess a high specific resistivity.

  • 15. Rosental, Arnold
    et al.
    Tarre, Aivar
    Gerst, Alar
    Kasikov, Aarne
    Lu, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Ottosson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Uustare, Teet
    Epitaxial Single and Double Nanolayers of SnO2 and TiO2 for Resistive Gas Sensors2013Inngår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, nr 5, s. 1648-1655Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rutile TiO2 (1 0 1) and cassiterite SnO2 (1 0 1) epitaxial single and double nanolayers, the latter stacked in either sequence, are atomic layer deposited on r-cut alpha-Al2O3(0 1 (1) over bar 2) substrates. Thickness of the layers is varied. Epitaxial quality of the films is characterized by X-ray diffraction (XRD), reflection high-energy electron diffraction, and transmission electron microscopy. In gas response measurements, as-grown films and the films coated with electron-beam evaporated Pt nanoclusters are exposed, at 350 degrees C, to H-2, CO, and CH4 diluted in air. In response to test gas concentrations of 30 parts per million (ppm), the films with a thickness of order of 10 nm exhibit, depending on the makeup and gas, as high as two- to five-fold decrease in the resistance. It is shown that the platinum surface catalyst is effective in accelerating the response and recovery processes. The transition times of the order of a few tens of seconds are observed. The results demonstrate the feasibility of gas sensing with single-crystal-like nanolayer films. Comparison of sensor characteristics of such quasi-2D nanostructures and the literature data relevant to individual nanowires, nanorods, and nanobelts, i.e., typical representatives of the quasi-1D structures, shows that, as to H-2, CO, and CH4, both structures are worthy competitors.

  • 16. Sammelselg, V.
    et al.
    Tarre, A.
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrostrukturlaboratoriet, MSL.
    Aarik, J.
    Niilisk, A.
    Uustare, T.
    Netsipailo, I.
    Rammula, R.
    Parna, R.
    Rosental, A.
    Structural characterization of TiO2–Cr2O3 nanolaminates grown by atomic layer deposition2010Inngår i: Surface and Coatings Technology, ISSN 0257-8972, Vol. 204, nr 12-13, s. 2015-2018Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    TiO2-Cr2O3 nanolaminates were atomic layer deposited on (0 1 2)-oriented sapphire and (1 0 0)-oriented silicon. The thickness of the alternating layers in the eight-layer laminates grown was close to 10 nm. The laminates were characterized by cross-sectional high-resolution transmission electron microscopy, high-resolution scanning electron microscopy, atomic force microscopy, reflection high-energy electron diffraction, and micro-Raman spectroscopy. A highly oriented growth of the laminate on sapphire and its growth with a very little preferred orientation on silicon were revealed. The laminate grown on sapphire had, along with better crystallinity. more exactly defined and more planar interphase boundaries. The amount of indefiniteness of the boundaries increased with the layer distance from the substrate. The crystalline phase of titania was rutile in the laminate grown on sapphire and anatase in the laminate grown on silicon, while the crystalline phase of chromia had eskolaite structure. In the laminate grown on sapphire, titania contained numerous twins: compressively strained chromia had in this case more perfect structure.

  • 17.
    Yang, Jiaojiao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Han, Yuanyuan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Liefer, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    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.
    Synthesis and Characterization of Amorphous Magnesium Carbonate Nanoparticles2019Inngår i: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 224, s. 301-307Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the template-free, low-temperature, environment-friendly synthesis of amorphous magnesium carbonate nanoparticles (AMN). Scanning electron microscopy and transmission electron microscopy show that AMN consist of small nanoparticles approximately 20-65 nm in diameter. Drying temperature and centrifugation are shown to affect the nanostructure and functional properties of the material. Aggregated AMN can be produced with a total pore volume up to 1.72 cm(3)/g and can absorb as much as 24 mmol/g water, substantially surpassing the pore volume and moisture-absorbing capacity of all previously described alkali earth metal carbonates. The nanoparticles are foreseen to be useful in applications such as water sorption, drug delivery and catalysis.

  • 18.
    Yang, Jiaojiao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Luo, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Welch, Ken
    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. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Adhesives from Inorganic Nanoparticles and Low-Molecular-Weight Organic CompoundsManuskript (preprint) (Annet vitenskapelig)
1 - 18 of 18
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