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  • 101.
    Kassman Rudolphi, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The contact resistance of rolling silver coated copper contacts1997In: Proc. 43rd IEEE Holm Conf. on Electrical Contacts, 1997, p. 33-40Conference paper (Refereed)
  • 102.
    Kassman Rudolphi, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The role of gross plastic fretting in serviceability and deterioration of power contacts1996Conference paper (Refereed)
  • 103.
    Kassman, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Surface damage, adhesion and contact resistance of siler coated plated copper contacts subjected to fretting motion1993In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 165, no 2, p. 227-230Article in journal (Refereed)
  • 104.
    Kassman, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Erickson, Lynn
    Hedenqvist, Per
    Olsson, Mikael
    A new test method for the intrinsic abrasion resistance of thin coatings1991In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 50, no 1, p. 75-84Article in journal (Refereed)
  • 105.
    Klaus-Joerger, Tanja
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Joerger, Ralph
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Olsson, Eva
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Bacteria as workers in the living factory: metal-accumulating bacteria and their potential for materials science2001In: Trends in Biotechnology, ISSN 0167-7799, E-ISSN 1879-3096, Vol. 19, no 1, p. 15-20Article, review/survey (Refereed)
    Abstract [en]

    Metal micro-/nano-particles with suitable chemical modification can be organized into new ceramic–metal (cermet) or organic–metal (orgmet) composites or structured materials. These materials are attracting significant attention because of their unique structures and highly optimized properties. However, the synthesis of composite materials with inhomogeneities on the nanometer or sub-micrometer scale is a continuing challenge in materials science. Many industrial physical and chemical surface-coating processes using conventional techniques are both energy and cost inefficient and require sophisticated instrumentation. In the future, biology might offer a superior option.

  • 106.
    Krieg, Marie-Louise
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Impact of Oxygen-Release Material on Human Urine-Derived Stem Cells’ Differentiation and Proliferation in Hypoxic Condition In Vitro2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One of today’s most widely spread health problems is urinary incontinence, affecting 60-80% of the US population from age 15 and up. Treatment based on the possibility to implant a scaffold seeded with the patients’ own urine-derived stem cells, hUSC, to regenerate the damaged muscle tissue, would prove effective. A main challenge in regenerating new tissue from cell-seeded scaffolds is the limited cell survival due to insufficient oxygen diffusion to the center of the scaffold. Ways of enhancing cell survival, and thereby, proliferation and differentiation, is by hypoxic preconditioning of the cells or implantation in an oxygen-release material. Hypoxic preconditioning has shown to enhance proliferation as well as the expression of vascular endothelial growth factor, VEGF, in for example human bone marrow derived stem cells, hBMSC. VEGF is involved in the establishment of vasculature structures and an upregulation of its expression may therefore help promote quicker angeogenisis, increasing the oxygen supply and the cell survival. Oxygen-release materials have shown to enhance cell survival and growth both in vitro and in vivo.

    This study aims to investigate the effect of hypoxia on hUSC, during 9 days of hypoxic culturing (2.0% ± 0.1% O2) with and without oxygen-release material (PLGA 75:25 with 5 w% CPO) in vitro. hBMSC, and human smooth muscle cells, hSMC, have been used as control groups. Cell proliferation, morphology, differentiation, production of VEGF, and expression of hypoxia inducible factor HIF-1α have been studied.

    According to the results, combining hypoxic preconditioning of hUSC with implantation in oxygen-release material could be an effective way to regenerate muscular tissue. Hypoxic preconditioning enhanced cell proliferation, production of VEGF, and HIF-1α expression. The increase of VEGF and HIF-1α would promote vascularization when implanted. The oxygen-release material showed possible promotion of cell differentiation, which would augment the hUSCs’ myogenic differentiation, while supplying oxygen until the tissue’s vascular structure has been established.

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  • 107.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Electron microscopy and nano-engineering.
    Quantitative electron microscopy2006In: Proceedings of conference on density functional theory and TEM, Wien, March 2006, 2006Conference paper (Other academic)
  • 108.
    Lewin, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Olsson, Erik
    André, Benny
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Joelsson, Torbjörn
    Öberg, Åke
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ljungcrantz, Henrik
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Industrialisation Study of Nanocomposite nc-TiC/a-C Coatings for Electrical Contact Applications2009In: Plasma Processes and Polymers, ISSN 1612-8850, Vol. 6, no S1, p. S928-S934Article in journal (Refereed)
    Abstract [en]

    Nanocomposite nc-TiC/a-C coatings were prepared by non-reactive magnetron sputtering in industrial scale equipment, under varying deposition conditions in order to investigate upscaling and possible industrialisation. The coatings were found to have similar microstructure and performance compared to previous laboratory scale experiments. The samples were characterised with XRD, XPS and SEM as well with ball-on-disc, nanoindentation and electrical measurements. Coatings containing a small fraction of a-C matrix phase were found to have promising both electrical properties (rho < 400 mu Omega cm and contact resistances down to 0.34 m Omega at 40 N) and tribological properties (f < 0.3 for 10 000 laps).

  • 109.
    Lidbaum, Hans
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Elektronmikroskopi och nanoteknologi.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Elektronmikroskopi och nanoteknologi.
    Structural transitions in multilayered thin films and their impact on the magnetic properties2006Conference paper (Other (popular science, discussion, etc.))
  • 110. Liddle, A
    et al.
    Borse, V
    Skrzypic, D
    Timothy, J
    Jacob, J
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kapur, N
    Hall, Richard
    The use of bone cement to minimize interbody device subsidence2015Conference paper (Other (popular science, discussion, etc.))
  • 111.
    Lindahl, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Borchardt, Per
    Department of Chemistry and Materials Technology, SP Technical Research Institute of Sweden.
    Lausmaa, Jukka
    Department of Chemistry and Materials Technology, SP Technical Research Institute of Sweden.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Studies of early growth mechanisms of hydroxyapatite on single crystalline rutile: a model system for bioactive surfaces2010In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 21, no 10, p. 2743-2749Article in journal (Refereed)
    Abstract [en]

    Previous studies have shown that crystalline titanium oxide is in vitro bioactive and that there are differences in the HA formation mechanism depending on the crystalline direction of the titanium oxide surface. In the present study, the early adsorption of calcium and phosphate ions on three different surface directions of the single-crystal rutile TiO2 substrate has been investigated. A crucial step in the nucleation of HA is believed to be the adsorption of Ca2+ and PO4 3− from phosphate buffer solutions. The (001), (100) and (110) single crystalline rutile surfaces were soaked in phosphate buffer saline solution for 10 min, 1 h and 24 h at 37°C. The surfaces were then analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS). The results show that the adsorption of Ca2+ and PO4 3− is faster on the (001) and (100) surfaces than on the (110) surface. This study also shows that TOF-SIMS can be used as a tool to better understand the adsorption of calcium and phosphate ions and the growth mechanism of HA. This knowledge could be used to tailor new bioactive surfaces for better biological reaction.

  • 112.
    Lindahl, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Snis, Anders
    Arcam AB, Sweden.
    Lausmaa, Jukka
    Palmquist, Anders
    Department of Biomaterials, Sahlgrenska Academy at the University of Gothenburg, Gothenburg.
    Biomimetic calcium phosphate coating of additively manufactured porous CoCr implants2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 353, p. 40-47Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to study the feasibility to use a biomimetic method to prepare biomimetic hydroxyapatite (HA) coatings on CoCr substrates with short soaking times and to characterize the properties of such coatings. A second objective was to investigate if the coatings could be applied to porous CoCr implants manufactured by electron beam melting (EBM). The coating was prepared by immersing the pretreated CoCr substrates and EBM implants into the phosphate-buffered solution with Ca2+ in sealed plastic bottles, kept at 60 degrees C for 3 days. The formed coating was partially crystalline, slightly calcium deficient and composed of plate-like crystallites forming roundish flowers in the size range of 300-500 nm. Cross-section imaging showed a thickness of 300-500 nm. In addition, dissolution tests in Tris-HCl up to 28 days showed that a substantial amount of the coating had dissolved, however, undergoing only minor morphological changes. A uniform coating was formed within the porous network of the additive manufactured implants having similar thickness and morphology as for the flat samples. In conclusion, the present coating procedure allows coatings to be formed on CoCr and could be used for complex shaped, porous implants made by additive manufacturing.

  • 113.
    Lindahl, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lausmaa, Jukka
    Department of Chemistry and Materials Technology, SP Technical Research Institute of Sweden, Borås, Sweden .
    Borchardt, Per
    Department of Chemistry and Materials Technology, SP Technical Research Institute of Sweden, Borås, Sweden .
    Thomsen, Peter
    Institute for Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Co-substituted strontium and silicon apatite coatings for metallic implants2010In: Seventh SICOT/SIROT Annual International Conference, Gothenburg, Sweden, 2010., 2010Conference paper (Refereed)
  • 114.
    Lindahl, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Thomsen, Peter
    Institute for Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden .
    Lausmaa, Jukka
    Department of Chemistry and Materials Technology, SP Technical Research Institute of Sweden .
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Co-mineralization of fluoride substitued hydroxyapatite/TiO2 coating on Ti implants through a biomineralization process2009In: Scandinavian Society for Biomaterials (ScSB)  annual meeting 2009, Copenhagen, Denmark, 2009Conference paper (Refereed)
  • 115.
    Lindgren, M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Åstrand, M
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Investigation of boundary conditions for biomimetic HA deposition on titanium oxide surfaces2009In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 20, no 7, p. 1401-1408Article in journal (Refereed)
    Abstract [en]

    To improve the clinical outcome of metal implants, i.e. earlier loading and reduction of the incidence of revision surgery, better bone bonding ability is wanted. One method to achieve this is to change the surface chemistry to give a surface that facilitates bone bonding in vivo, i.e. a bioactive surface. Crystalline titanium oxide has recently been proven to be bioactive in vitro and is an interesting option to the more common hydroxylapatite (HA) coatings on implants. A materials possible in vitro bioactivity is tested through soaking in simulated body fluid and studies of possible HA formation on the surface. For bioactive materials, the formed HA layer can also be used as a coating. The aim of the current paper is to investigate some boundary conditions for HA formation on crystalline titanium oxide surfaces regarding influence from coating thickness, soaking time and soaking temperature. The influence from soaking time and temperature on the HA growth were investigated on oxidised Ti samples, (24 h at 800°C) resulting in a rutile surface structure. The oxidised samples were tested at three temperatures (4, 37 and 65°C) and four times (1 h, 1 day, 1 week and 4 weeks). The influence from titanium coating thickness on the HA growth was investigated via depositing thin films of crystalline titanium dioxide on Ti plates using a reactive magnetron sputtering process. Four different PVD runs with coating thicknesses between 19 and 74 nm were tested. The soaking temperature had an effect on the HA formation and growth on both rutile surfaces and native oxide on Ti substrates. Higher temperatures lead to easier formation of HA. It was even possible, at 65°C, to grow HA on native titanium oxide from soaking in PBS. The coating quality was better for HA formed at 65°C compared to 37°C. All PVD-coatings showed HA growth after 1 week in PBS at 37°C, thus even very thin coatings of crystalline titanium oxide coatings are bioactive.

  • 116.
    Lindquist, M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wilhelmsson, O
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Jansson, U
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tribofilm formation and tribological properties of nanocomposite TiC and TiAlC coatings2007Conference paper (Refereed)
  • 117.
    Lindquist, Mattias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wilhelmsson, Ola
    Jansson, Ulf
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tribofilm formation and tribological properties of TiC and nanocomposite TiAlC coatings2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 266, no 3-4, p. 379-387Article in journal (Refereed)
    Abstract [en]

    In a recent work a concept for self lubricating low friction TiC and nanocomposite TiAlC coatings was developed. Here we further investigate the mechanical and tribological properties of these coatings. Under identical deposition conditions, the addition of Al initiates the formation of a nanocomposite consisting of (Ti,Al)C grains in an amorphous carbon matrix. The coefficient of friction is lowered from 0.2 to below 0.1 in a pin-on-disc test against steel with unaffected coating wear rate. The lower friction is attributed to a more extensive formation of amorphous carbon and graphitisation on both the counter surface and in the coating wear track. The addition of Al also reduces coating hardness, Young's modulus and the residual stress, which can be explained by the weak carbide-forming ability of Al and the formation of a nanocomposite microstructure.

  • 118.
    Lindquist, Mattias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wilhelmsson, Ola
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tribofilm formation from TiC and nanocomposite TiAlC coatings, studied with Focused Ion Beam and Transmission Electron Microscopy2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 266, no 9-10, p. 988-994Article in journal (Refereed)
    Abstract [en]

    This work demonstrate how two different carbide coatings respond very differently to tribological stress and their very different ability to provide low friction tribofilms in dry sliding against steel. Both coatings, TiC and TiAlC, were deposited by DC-magnetron sputtering, but while the TiC is a thermodynamically stable coating, the TiAlC is made metastable with the addition of Al, and therefore releases carbon upon tribological testing. Thus, the TiAlC coating is shown to be self-lubricating on the atomic scale which makes very low friction   achievable. The primary interest in this study is the differences in the tribofilms formed on the steel balls that have been sliding against  the two coatings. Cross-section samples for transmission electron  microscopy were extracted from the ball tribofilms using a focused ion beam instrument. X-ray photoelectron spectroscopy and Raman analysis were employed to provide information on the chemical and structural  characteristics of the tribofilms. It was shown that tribofilms on steel balls largely inherit the structure and composition that evolve   in the coating wear tracks, that the tribofilm microstructure greatly affects the friction level. It was also shown that tribofilm delamination, occurring with tribofilm growth, was initiated in weak ribbon like regions inside the tribofilm.

  • 119.
    Liu, Yang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Harbin Institute of Technology.
    Zhang, mingfu
    Harbin Institute of Technology.
    Wu, Dan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wang, Tao
    Harbin Institute of Technology.
    Ying, Nie
    Harbin Institute of Technology.
    Han, Jiecai
    Harbin Institute of Technology.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Microstructures and mechanical properties of Al2O3/YAG:Ce3+ eutectics with different Ce3+concentrations grown by HDS method2019In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669Article in journal (Refereed)
  • 120.
    Longtin, R
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Fauteux, C
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Coronel, E
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, U
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Pegna, J
    Boman, M
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Nanoindentation of carbon microfibers deposited by laser-assisted chemical vapor deposition2004In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 79, no 3, p. 573-7Article in journal (Refereed)
    Abstract [en]

    Carbon microfibers were deposited using laser-assisted chemical vapor deposition at atmospheric and sub-atmospheric pressures. Precursor pressures and incident laser powers were varied. Fibers were cast in acrylic resin and polished to allow nanoindentation of the cross sections. Cross-sectional roughness was examined by optical profilometry. A radial change in mechanical properties was observed. The local elastic modulus (Young's modulus) and hardness for the edge and core regions are reported. These mechanical properties were investigated with respect to deposition parameters and corresponding fiber microstructure

  • 121.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Injectable biodegradable composites for the degenerated intervertebral disc2010In: GRIBOI Congress, Turin, 2010, 2010Conference paper (Refereed)
  • 122.
    López, Alejandro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Synthesis and characterization of injectable composites of poly[D,L-lactide-co-(ε-caprolactone)] reinforced with β-TCP and CaCO3 for intervertebral disk augmentation.2010In: Journal of Biomedical Materials Research, Part B: Applied Biomaterials, ISSN 15524973, Vol. 95B, no 1, p. 75-83Article in journal (Refereed)
    Abstract [en]

    Degeneration of the intervertebral disk constitutes one of the major causes of low back pain in adults aged 2050 years old. In this study, injectable, in situ setting, degradable composites aimed for intervertebral disk replacement were prepared. beta-TCP and calcium carbonate particles were mixed into acrylic-terminated oligo[D,L-lactide-co-(epsilon-caprolactone)], which were crosslinked at room temperature. The structure of the oligomers was confirmed by H-1-NMR spectroscopy. The composites were examined via SEM, and the mechanical properties of the crosslinked networks were determined. The porous beta-TCP particles showed good mechanical anchorage to the matrix due to polymer penetration into the pores. In vitro degradation tests showed that the composites containing beta-TCP slowly degraded, whereas the composites containing CaCO3 exhibited apatite formation capacity. It was concluded that the surface area, morphology, and solubility of the fillers might be used to control the degradation properties. The incorporation of fillers also increased both the elastic modulus and the maximum compression strength of the composites, properties that were similar to those of the physiological disk. These materials have potential for long-term intervertebral disk replacement and regenerative scaffolds because of their low degradation rates, bioactivity, and mechanical properties.

  • 123.
    Lööf, Jesper
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Svahn, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jarmar, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Pameijer, Cornelis H.
    A comparative study of the bioactivnity of three materials for dental applications2008In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 24, no 5, p. 653-659Article in journal (Refereed)
    Abstract [en]

    Objectives. The aim of this work was to investigate the in vitro bioactivity of two different experimental dental luting cement formulations based on calcium aluminate (CA) in comparison with glass ionomer cement (GIC). One of the CA-based formulations was a hybrid between CA and GIC. Methods. Samples were submerged in phosphate buffered saline and stored at 37 degrees C for four periods of time: 1 h, 1 day, 7 days and 4 weeks. After storage the samples were analyzed in order to investigate if a surface layer of hydroxyapatite had formed. The analysis techniques used included grazing incidence X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy. Results. Both the CA-containing formulations were found to be bioactive. The highest degree of bioactivity was found on the sample with only CA as active substance. A relatively thick and totally covering layer was already formed after 24 h. On the hybrid material hydroxyapatite was found after 7 days. The GIC showed no bioactivity during the test period. Significance. The utilization of a bioactive material for tooth restorations will give an opportunity for remineralization and a natural and durable seal of the tooth-material interface. Materials based on CA exhibit bioactivity.

  • 124.
    Malmros, Martina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Nanocomposite Coatings for Contact Brush Applications2010In: Proceedings of the 4th International Tribology Congress, ASIATRIB2010 / [ed] G. Stachowiak, 2010Conference paper (Refereed)
  • 125.
    Mihranyan, Albert
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Forsgren, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Assessing Surface Area Evolution during Biomimetic Growth of Hydroxyapatite Coatings2009In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, no 3, p. 1292-1295Article in journal (Refereed)
    Abstract [en]

    The surface area of biomimetically deposited hydroxyapatite (HA) coatings on metallic implants is important for the biological performance of the implant. Thus, a nondestructive method of assessing this quantity directly on the solid substrate would be highly valuable. The objective of this study was to develop such a method and for the first time assess the evolution of surface area of HA during biomimetic growth. The surface area of a TiO2-covered titanium substrate was measured prior to and following the biomimetic coating deposition using Ar gas adsorption at 77 K. The presence of HA on the surface was verified with scanning electron microscopy and X-ray diffraction. The specific surface area of the coating was found to increase linearly during 1 week of deposition at a rate of ∼100 cm2 day−1 (g substrate)−1. The presented method may be used as a tool for studying the evolution in surface area of coatings on solid substrates during biomimetic deposition or other growth processes.

  • 126. Mohan, D. Bharathi
    et al.
    Svahn, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Cavaleiro, A.
    Deposition of TiN-WS2-Nanocomposite Coatings by a Hybrid Process: Reactive Sputtering and Clusters Gun2009In: Plasma processes and polymers, Vol. 6, p. S923-S927Article in journal (Refereed)
    Abstract [en]

    A dc magnetron reactive sputtering equipment connected with a homemade clusters gun was used to deposit a series of TiN-WS2-nanocomposite coatings with different magnetron power values and different argon pressures in the clusters gun. The original idea was to achieve from the TiN matrix, originated from the normal running of the magnetron system, the high wear resistance property, whereas the pre-formed IF-WS2 nanospheres introduced by the clusters gun would provide the low friction coefficient. A small peak detected at low diffraction angles by X-ray diffraction in two of the produced samples gave the first evidence of the WS2 nanospheres incorporation in the TiN matrix. Then, scanning electron microscopy was used for observing very small grain features which were identified as the WS2 nanospheres by energy dispersive analysis of X-rays, demonstrating the feasibility of this hybrid technique for the deposition of nanocomposite coatings.

  • 127. Neovius, Erik
    et al.
    Fransson, Maria
    Matthis, Sköld Peter
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Östlund, Sophie
    Farnebo, Filip
    Lundgren, T. Kalle
    Persistent diplopia after fractures involving the orbit related to nerve injury2015In: Journal of Plastic, Reconstructive & Aesthetic Surgery, ISSN 1748-6815, E-ISSN 1532-1959, Vol. 68, no 2, p. 219-225Article in journal (Refereed)
    Abstract [en]

    Background: Fractures in the facial skeleton are common and may lead to orbital sequelae caused by the injury and/or the surgery. In this long-term follow-up, we examined the nature of sequelae after facial fractures involving the orbit and whether a higher complexity of the fractures produced more sequelae compared to simpler fracture patterns, and if so, to what extent. Methods: Patients surgically treated for facial fractures involving the orbit at the Karolinska University Hospital with a follow-up duration of >= 3 years were included in this retrospective study and were examined by a neuro-ophthalmologist. Based on the location and severity of the fractures, the patients were divided into four groups according to fracture complexity: 1) isolated zygomatic fracture, 2) isolated orbital floor blowout fracture, 3) zygomatic fracture combined with blowout fracture and 4) bilateral or multiple fracture patterns. Results: Out of 154 patients, 81 patients (53%) attended follow-up examinations, 65 male (80%) and 16 female (20%). The duration of follow-up was 3.0-7.6 years (mean of 4.9 years). The incidence of diplopia was 3.7%, visual loss 2.5%, dystopia 4.9% and visible enophthalmos (>2 mm) 8.6%. Severe diplopia (2.5%) was due to nerve injuries. Visual loss was encountered only in group 4 with complex fractures. Fracture complexity had an effect on the presence of any sequelae, with group 4 presenting a higher percentage of patients with sequelae than the other three groups. However, no statistically significant effect of group could be found on the individual, quantitative output values of dystopia and enophthalmos. Conclusions: In this study, severe persistent diplopia in patients was due to nerve injuries, which emphasizes the need for preoperative ophthalmologic examinations, in all patients with fractures involving the orbit. A higher fracture complexity was found to lead to a higher percentage of patients presenting sequelae. (C) 2014 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  • 128.
    Neovius, Erik
    et al.
    Stockholm Craniofacial Center, Department of Reconstructive Plastic Surgery, Karolinska University Hospital, Stockholm, Sweden & Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden.
    Fransson, Maria
    Department of General Surgery, Sundsvall-Härnösand County Hospital, Sundsvall, Sweden.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Clarliden, Sophie
    Department of Oral- & Maxillofacial Surgery, Örebro University Hospital, Sweden.
    Farnebo, Filip
    Stockholm Craniofacial Center, Department of Reconstructive Plastic Surgery, Karolinska University Hospital, Stockholm, Sweden & Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden.
    Lundgren, T. Kalle
    Stockholm Craniofacial Center, Department of Reconstructive Plastic Surgery, Karolinska University Hospital, Stockholm, Sweden & Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden.
    Long-term sensory disturbances after orbitozygomatic fractures2017In: Journal of Plastic, Reconstructive & Aesthetic Surgery, ISSN 1748-6815, E-ISSN 1532-1959, Vol. 70, p. 120-126Article in journal (Refereed)
    Abstract [en]

    Background: Orbitozygomatic fractures often lead to infraorbital nerve (ION) injury, and affected sensibility is a common long-term complaint within this patient group. We present a long-term follow-up study where the validated von Frey filament system was used for testing ION sensibility. Furthermore, we examined the incidence of persistent nerve injury and whether more complex fractures led to more pronounced ION sensibility disturbances. Methods: Patients treated for facial fractures involving the orbitozygomatic complex were included and the follow-up time was 3 years or more. Depending on the location and severity of the fractures, the patients were divided into 4 groups. The patients answered a questionnaire before ION sensibility testing with von Frey filaments. Results: Eighty-one patients were examined: 65 males (80%) and 16 females (20%). Examinations were conducted between 3.0 and 7.6 years (mean 4.9 years) after injury. Sixteen patients (20%) had affected and 6 patients (7.4%) had severely affected ION sensibility according to von Frey testing. No statistically significant differences were found in terms of questionnaire score between the groups. There was also no statistically significant correlation between questionnaire results and log von Frey values. Although the effect of groups could not be statistically verified using the log von Frey values, a larger proportion of patients with complex fractures had higher log von Frey values than the other groups

  • 129.
    Neto, Jose
    et al.
    Federal University of Santa Catarina.
    Fredel, M.C.
    Federal University of Santa Catarina.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hexagonal ion doped Calcium phosphates2014Conference paper (Refereed)
  • 130.
    Nikolajeff, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Materialvetenskap.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Uppsala Berzelii Technology Center: Swedish Center to Target Neurodegenerative Diseases2006Other (Other (popular science, discussion, etc.))
  • 131.
    Nilsson, D
    et al.
    MATERIALS SCIENCE / TRIBOLOGY. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Coronel, E
    Wiklund, U
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effects of substrate bias polarity on tribological a-C:Ta coatings2002In: AUSTRIB ´02, Perth, 2002Conference paper (Refereed)
  • 132.
    Nilsson, D
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Stavlid, N
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lindquist, M
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hogmark, Sture
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The role of aluminum additions in the oxidation and wear of a TaC:C low-friction coating2009In: Surface and Coatings Technology, ISSN 0257-8972, Vol. 203, no 20-21, p. 2989-2994Article in journal (Refereed)
    Abstract [en]

    A very attractive feature possessed by many carbon-based coatings is the ability to provide a combination of lowered friction and high wear resistance in various sliding contact situations. The flair for low friction is commonly attributed to large amounts of surplus carbon present in the microstructure. However, the surplus carbon also makes these coatings rather susceptible to oxidation. To expand the field of application for carbon-based low-friction coatings it is important to improve their oxidation resistance. Of course this must not be accomplished by impairing their main function, of giving low friction. In an attempt to increase the oxidation resistance of a TaC:C coating without sacrificing its extremely good tribological behaviour, Al was added in increasing amounts at the expense of carbon. The effects of Al addition was evaluated on as-deposited coatings from a mechanical and tribological standpoint. The oxidation resistance of the coatings was evaluated in air at temperatures up to 500C and the resulting oxides were analyzed as to their chemistry and thickness. The oxidation rate was found to decrease quite rapidly with increasing amounts of Al. Moreover, it was found that the Al addition could be optimized to give low friction and reduced oxidation rate at only a moderate increase in wear rate.

  • 133.
    Nilsson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Modified PMMA for osteoporotic vertebral fracture - reason for a better suited PMMA cement for fragile bone.2017Conference paper (Refereed)
  • 134.
    Nordh, L-G
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Broqvist, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Miller, P
    Gunnarsson, S
    Machinability of high performance die steels2003In: Transactions of the 22nd International Die Casting Congress and Exposition: Die casting in the heartland : September 15-17, 2003, Indianapolis, Indiana, Rosemont, Ill.: North American Die Casting Association , 2003, , p. 327-335p. 327-335Conference paper (Other academic)
  • 135.
    Nyberg, Harald
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Olofsson, Johanna
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gerth, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    On the influence from micro topography on the structure and growth of low friction amorphous carbon PVD coatings2010In: Twelfth International Conference on Plasma Surface Engineering (PSE 2010), September 13-17, 2010, Garmisch-Partenkirchen, 2010Conference paper (Refereed)
    Abstract [en]

    The interest in metal carbide doped amorphous carbon coatings produced by physical vapour deposition (PVD) for use on heavily stressed machine elements is currently increasing, mainly due to their ability to achieve low friction and reduced wear of the counter surface. The tribological properties of these types of coatings have however been found to vary strongly between seemingly similar coatings. A potential source of these differences could be the micro topography of the coated surfaces.

     

    Argon ion etch cleaning of the substrates is a common process step in the production of PVD coatings and is usually performed as the final cleaning step before coating deposition. For some materials, the etching process may result in a roughening of the substrate surface, due to differences in the etch rates of the different parts of the material. In high speed steels, carbides typically etch slower than the metallic phase, resulting in a surface covered by protruding carbides.

     

    In the current study, it was examined how varying amounts of argon ion etching of highly polished high speed steel substrates prior to coating influences the micro topography of the substrates and the final coatings. Tantalum carbide doped amorphous carbon coatings (TaC:C) were produced by co-sputtering of carbon and tantalum, in an argon atmosphere. The impact of the substrate micro topography on the growth and structure of the coatings was studied, using high resolution scanning electron microscopy (SEM) of superficial coating cross sections produced with a focused ion beam (FIB). Special attention was paid to coating growth in the immediate vicinity of protruding carbides, as well as to the structure of the coating in these regions.

  • 136.
    Oladokun, A.
    et al.
    Institute of Functional Surfaces (iFS), School of Mechanical Engineering, University of Leeds, Leeds, UK.
    Pettersson, M.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Caring Sciences. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Centre for Research Ethics and Bioethics.
    Bryant, M.
    Institute of Functional Surfaces (iFS), School of Mechanical Engineering, University of Leeds, Leeds, UK.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hall, Richard
    Institute of Functional Surfaces (iFS), School of Mechanical Engineering, University of Leeds, Leeds, UK.
    Neville, A.
    Institute of Functional Surfaces (iFS), School of Mechanical Engineering, University of Leeds, Leeds, UK.
    Fretting of CoCrMo and Ti6Al4V alloys in modular prostheses2015In: Tribology - Materials, Surfaces & Interfaces, ISSN 1751-5831, E-ISSN 1751-584X, Vol. 9, no 4, p. 165-173Article in journal (Refereed)
    Abstract [en]

    Implantation of a total hip replacements (THR) is an effective intervention in the management of arthritis. Modularity at the taper junction of THR was introduced in order to improve the ease with which the surgeon could modify the length of the taper section and the overall length of the replacement. Cobalt chromium (Co–28Cr–6Mo) and titanium (Ti–6Al–4V) alloys are the most commonly used materials for the device. This study investigates the fretting behaviour of both CoCr–CoCr and CoCr–Ti couplings and analyses their damage mechanisms. A reciprocating tribometer ball on plate fretting contact was instrumented with in situelectrochemistry to characterise the damage inflicted by tribocorrosion on the two couplings. Fretting displacements amplitudes of 10, 25 and 50 μm at an initial contact pressure of 1 GPa were assessed. The results reveal larger metallic volume loss from the CoCr–CoCr alloy compared to the CoCr–Ti alloy, and the open circuit potential indicates a depassivation of the protective oxide layer at displacement amplitudes >25 μm. In conclusion, the damage mechanisms of CoCr–CoCr and CoCr–Ti fretting contacts were identified to be wear and fatigue dominated mechanisms respectively.

  • 137.
    Olofsson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Grehk, T. Mikael
    Sandvik Materials Technology.
    Berlind, Torun
    Linköpings universitet, Institutionen för Fysik, Kemi och Biologi (IFM).
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Evaluation of silicon nitride as a wear resistant and resorbable alternative for total joint replacement2012In: Biomatter, ISSN 2159-2527, Vol. 2, no 2, p. 94-102Article in journal (Refereed)
    Abstract [en]

    Many of the failures of total joint replacements are related to tribology, i.e., wear of the cup, head and liner. Accumulation of wear particles at the implants can be linked to osteolysis which leads to bone loss and in the end aseptic implant loosening. Therefore it is highly desirable to reduce the generation of wear particles from the implant surfaces.

    Silicon nitride (Si3N4) has shown to be biocompatible and have a low wear rate when sliding against itself and is therefore a good candidate as a hip joint material. Furthermore, wear particles of Si3N4 are predicted to slowly dissolve in polar liquids and they therefore have the potential to be resorbed in vivo, potentially reducing the risk for aseptic loosening.

    In this study, it was shown that α-Si3N4-powder dissolves in PBS. Adsorption of blood plasma indicated a good acceptance of Si3N4 in the body with relatively low immune response. Si3N4 sliding against Si3N4showed low wear rates both in bovine serum and PBS compared with the other tested wear couples. Tribofilms were built up on the Si3N4 surfaces both in PBS and in bovine serum, controlling the friction and wear characteristics.

  • 138.
    Olofsson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The Role of Surface Treatment in the Tribofilm Formation on Alumina Friction Drive Components2009In: World tribology congress 2009, Kyoto, 2009Conference paper (Refereed)
  • 139.
    Olofsson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Johansson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. PiezoMotor AB.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Analysis of the tribofilm formation on the friction drive surfaces of a piezoelectric motor2007In: ASME/STLE International Joint Tribology Conference, Parts A and B, 2007, p. 871-872Conference paper (Refereed)
  • 140.
    Olofsson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Johansson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. PiezoMotor AB.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influence from humidity on the alumina friction drive system of an ultrasonic motor2009In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 42, no 10, p. 1467-1477Article in journal (Refereed)
    Abstract [en]

    Miniaturized ultrasonic motors, based on piezoelectric movement, are rapidly developing and the number of commercial applications is steadily growing. The details of the friction drive system of these motors still need systematic studies to fully utilize the potential of the technique. The friction drive system transfers the high frequency oscillatory movement from the stator to a drive rail. The friction force should be maximized and stabilized to achieve the best motor performance, while maintaining a low wear rate.

    The mating parts of a friction drive system typically consist of alumina which is selected due to its relatively low wear rate and relatively high coefficient of friction. With increasing relative humidity, the friction coefficients of alumina ceramics generally decrease.

    This work examines how water and humidity affect a friction drive system with respect to coefficient of friction and wear of the mating surfaces. Ball-on-disc experiments were used to evaluate the tribological properties. The worn surfaces were studied by scanning electron microscopy.

    The coefficient of friction was found to be relatively low but stable with water on the surface but higher and more fluctuating in dryer conditions. The character of the worn surfaces did not clearly correlate to the friction behaviour.

  • 141.
    Olofsson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Johansson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. PiezoMotor AB.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Influences from humidity on the friction drive system of a piezoelectric motor2008Conference paper (Refereed)
  • 142.
    Olofsson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Johansson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. PiezoMotor AB.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The effect of grain size on the tribofilm formation on the alumina friction drive system of an ultrasonic motor2009In: ECOTRIB 09 / [ed] E. Ciulli, B. Piccigallo, R. Bassani, F. Franek, J. Vizintin, R. Crockett, Pisa: Edizioni ETS , 2009, p. 965-970Conference paper (Refereed)
  • 143.
    Olofsson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lindberg, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Johansson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. PiezoMotor AB.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    On the role of tribofilm formation on the alumina drive components of an ultrasonic motor2009Conference paper (Refereed)
    Abstract [en]

    Ultrasonic motors typically have a friction drive system to transfer the movement. The miniaturized motor type investigated here has a friction drive system consisting of two drive pads that transfer the high frequency oscillating movement of two piezoelectric elements to a linear drive rail. The pads and rail consist of alumina.

    Fiction tests were carried out to investigate how the coefficient of friction between the drive pads and the drive rail depends on the number of strokes of the rail. It was found to initially increase with the number of strokes and then stabilize.

    Scanning electron microscopy studies of the friction drive surfaces show how a tribofilm forms and develops with the number of strokes. Interestingly, the smooth tribofilm surface gives a higher coefficient of friction than the original rougher surface. To further investigate the nature of the tribofilm. cross section samples were produced with a focused ion beam instrument. The tribofilms show different characters and appear to form gradually by agglomeration and sintering of wear debris. Transmission electron microscopy showed the tribofilm to be amorphous and partly nano-crystal line. This high resolution investigation also clearly demonstrated that the tribofilm bonds very well to the underlying alumina grains.

    The processes of friction increase and tribofilm build-up stabilize early compared to the lifetime of the motor.

  • 144.
    Olofsson, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lindberg, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Johansson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. PiezoMotor AB.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    On the role of tribofilm formation on the alumina drive components of an ultrasonic motor2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 267, no 5-8, p. 1295-1300Article in journal (Refereed)
    Abstract [en]

    Ultrasonic motors typically have a friction drive system to transfer the movement. The miniaturized motor type investigated here has a friction drive system consisting of two drive pads that transfer the high frequency oscillating movement of two piezoelectric elements to a linear drive rail. The pads and rail consist of alumina.

    Fiction tests were carried out to investigate how the coefficient of friction between the drive pads and the drive rail depends on the number of strokes of the rail. It was found to initially increase with the number of strokes and then stabilize.

    Scanning electron microscopy studies of the friction drive surfaces show how a tribofilm forms and develops with the number of strokes. Interestingly, the smooth tribofilm surface gives a higher coefficient of friction than the original rougher surface. To further investigate the nature of the tribofilm. cross section samples were produced with a focused ion beam instrument. The tribofilms show different characters and appear to form gradually by agglomeration and sintering of wear debris. Transmission electron microscopy showed the tribofilm to be amorphous and partly nano-crystal line. This high resolution investigation also clearly demonstrated that the tribofilm bonds very well to the underlying alumina grains.

    The processes of friction increase and tribofilm build-up stabilize early compared to the lifetime of the motor.

  • 145.
    Olsson, Mikael
    et al.
    Dalarna University.
    Heinrichs, Jannica
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Yvell, Karin
    Dalarna University.
    Jacobson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    On the relevance of hardness as a material parameter in the deformation and wear of cemented carbides in rock drilling2014Conference paper (Other academic)
  • 146.
    Orhan, Münire
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Polylactide Foams Reinforced with Wood Fibers or Microfibrillated Cellulose2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The growing environmental awareness of pollution and climate change has set up newrules and regulations, which forces the industries to seek and satisfy the demand formore alternative and renewable products. Research has been launched for findingnovel lightweight materials for packaging, transportation and construction. Currently,there is an interest of finding new applications of new forms of cellulose since theyoffer low density and cost, renewability and biodegradability. The potential of usingnano-scale cellulose as reinforcement in novel forms of composite materials opens upa fairly new unresearched area.The primary goal with this project is to produce foams by composite materials. This isa part of the large scale European collaboration project SustainComp, which aims todevelop more "green" materials. A manufacturing process similar to papermaking isused to make completely renewable and biodegradable materials.In this study, a repeatable manufacturing method for foaming of wood fiber (WF) andmicrofibrillated cellulose (MFC) reinforced polylactide (PLA) composites was studiedand tailored to produce thermally adapted pre-forms with an uniform dispersion. Amanufacturing process based on a wet commingling technique, was used to preparethe pre forms with a significant drying step to avoid material degradation in thesubsequent melting and pressing steps. Furthermore, various characterizations werecarried out to get a more detailed understanding of the materials.The future looks promising for these types of novel materials, using this newtechnique of manufacturing pre-forms. However, it requires more studies to ensurethat there is a possibility of making foams of PLA pre-forms reinforced with MFC aswith the case for WF reinforced composites.

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  • 147. Palmquist, A.
    et al.
    Emanuelsson, L.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Thomsen, P.
    A current update of the FIB/TEM method used in implant research2009In: 2nd China-Europe Symposium on Biomaterials in Regenerative Medicine, Barcelona, Spain; 16-20th of November 2009, 2009Conference paper (Refereed)
  • 148.
    Palmquist, A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lindberg, F.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Branemark, R.
    Thomsen, P.
    P.Biomechanical, Histological and ultrastructural Analysis of Micro-and Nano-structured Titanium alloy Implants2009In: 55th Annual Meeting of the Orthopaedic Research Society. Las Vegas, USA; 22-25th February, 2009, 2009Conference paper (Refereed)
  • 149. Palmquist, A.
    et al.
    Malmström, J.
    Emanuelsson, L.
    Slotte, C.
    Adolfsson, E.
    Botton, G.
    Thomsen, P.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Morphological studies on machined implants of commercially pure titanium and titanium alloy (Ti6A14V).2009In: 55th Annual Meeting of the Orthopaedic Research Society. Las Vegas, USA; 22-25th of February, 2009, 2009Conference paper (Refereed)
  • 150. Palmquist, Anders
    et al.
    Lindberg, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Emanuelsson, Lena
    Brånemark, Rickard
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Thomsen, Peter
    Biomechanical, Histological and Ultrastructural Analyses of Laser Micro- and Nano-structured Titanium Alloy Implants: A Study in Rabbit2010In: Journal of Biomedical Materials Research - Part A, ISSN 1549-3296, Vol. 92A, no 4, p. 1476-1486Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate the biomechanical properties and ultrastructure of the bone response of partly laser-modified Ti6Al4V implants compared with turned, machined implants after 8 weeks in rabbit. The surface analyses performed with interference microscopy and electron microscopy showed increased surface topography with micro- and nano-sized surface features as well as increased oxide thickness of the modified surface. The biomechanical testing demonstrated a 270% increase in torque value for the surface modified implants compared with the control implants. Histological evaluation of ground sections of specimens subjected to biomechanical testing revealed ongoing bone formation and remodeling. A histological feature exclusively observed at the laser-modified surface was the presence of fracture in the mineralized bone rather than at the interface between the bone and implant. Transmission electron microscopy (TEM) was performed on Focused Ion Beam (FIB) prepared samples of the intact bone-implant interface, demonstrating a direct contact between nanocrystalline hydroxyapatite and the oxide of the laser-modified implant surface. In conclusion, laser-modified titanium alloy implants have significantly stronger bone anchorage compared with machined implants and show no adverse tissue reactions.

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