| 1. |
- Sarius, N. G., et al.
(författare)
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Contact Resistance of Ti-Si-C-Ag and Ti-Si-C-Ag-Pd Nanocomposite Coatings
- 2012
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 41:3, s. 560-567
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Tidskriftsartikel (refereegranskat)abstract
- Ti-Si-C-Ag-Pd and Ti-Si-C-Ag nanocomposite coatings were deposited by direct-current magnetron sputtering on Cu substrates with an electroplated Ni layer. Analytical electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy show that the nanocomposites consist of TiC, Ag:Pd, and amorphous SiC. The contact resistance of these coatings against a spherical Au-Co surface was measured for applied contact forces up to 5 N. Ti-Si-C-Ag-Pd coatings with Ag:Pd top coating had similar to 10 times lower contact resistance at contact forces below 1 N (similar to 10 m Omega at similar to 0.1 N), and 2 to 3 times lower for contact forces around 5 N (< 1 m Omega at 5 N), compared with the Ti-Si-C-Ag coating.
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| 2. |
- Eiler, Konrad, et al.
(författare)
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Oxygen reduction reaction and proton exchange membrane fuel cell performance of pulse electrodeposited Pt–Ni and Pt–Ni–Mo(O) nanoparticles
- 2022
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Ingår i: Materials Today Energy. - : Elsevier Ltd. - 2468-6069. ; 27
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Tidskriftsartikel (refereegranskat)abstract
- Proton exchange membrane fuel cells (PEMFCs) are an important alternative to fossil fuels and a complement to batteries for the electrification of vehicles. However, their high cost obstructs commercialization, and the catalyst material, including its synthesis, constitutes one of the major cost components. In this work, Pt–Ni and Pt–Ni–Mo(O) nanoparticles (NPs) of varying composition have been synthesized in a single step by pulse electrodeposition onto a PEMFC's gas diffusion layer. The proposed synthesis route combines NP synthesis and their fixation onto the microporous carbon layer in a single step. Both Pt–Ni and Pt–Ni–Mo(O) catalysts exhibit extremely high mass activities at oxygen reduction reaction (ORR) with very low Pt loadings of around 4 μg/cm2 due to the favorable distribution of NPs in contact with the proton exchange membrane. Particle sizes of 40–50 nm and 40–80 nm were obtained for Pt–Ni and Pt–Ni–Mo(O) systems, respectively. The highest ORR mass activities were found for Pt67Ni33 and Pt66Ni32–MoOx NPs. The feasibility of a single-step electrodeposition of Pt–Ni–Mo(O) NPs was successfully demonstrated; however, the ternary NPs are of more amorphous nature in contrast to the crystalline, binary Pt–Ni particles, due to the oxidized state of Mo. Nevertheless, despite their heterogeneous nature, the ternary NPs show homogeneous behavior even on a microscopic scale. © 2022 The Author(s)
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| 3. |
- Neher, Margit, et al.
(författare)
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Learning opportunities in rheumatology practice : A qualitative study
- 2015
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Ingår i: Journal of Workplace Learning. - : Emerald Group Publishing Limited. - 1366-5626 .- 1758-7859. ; 27:4, s. 282-297
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Tidskriftsartikel (refereegranskat)abstract
- Purpose – This paper aims to explore what opportunities for learning practitioners in rheumatology perceive of in their daily practice, using a typology of workplace learning to categorize these opportunities.Design/methodology/approach – Thirty-six practitioners from different professions in rheumatology were interviewed. Data were analyzed using conventional qualitative content analysis with a directed approach, and were categorized according to a typology of formal and informal learning.Findings – The typology was adjusted to ft the categories resulting from the analysis. Further analysis showed that work processes with learning as a by-product in general, and relationships with other people in the workplace in particular, were perceived as important for learning in the workplace. The use of many recognized learning opportunities was lower. Barriers for learning were a perceived low leadership awareness of learning opportunities and factors relating to workload and the organization of work.Research limitations/implications – The generalizability of results from all qualitative inquiries is limited by nature, and the issue of transferability to other contexts is for the reader to decide. Further studies will need to confrm the results of the study, as well as the proposed enhancement of the typology with which the results were categorized.Practical implications – The study highlights the importance of relationships in the workplace for informal learning in rheumatology practice. In the clinical context, locally adapted strategies at organizational and individual levels are needed to maximize opportunities for both professional and interprofessional informal learning, taking the importance of personal relationships into account. The fndings also suggest a need for increased continuing professional education in the specialty.Originality/value – The workplace learning typology that was used in the study showed good applicability to empirical health-care study data, but may need further development. The study confrmed that informal workplace learning is an important part of learning in rheumatology. Further studies are needed to clarify how informal and formal learning in the rheumatology clinic may be supported in workplaces with different characteristics.
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| 4. |
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| 5. |
- Birmpilis, Georgios, 1988, et al.
(författare)
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Towards a methodology for the characterisation of the fabric of wet clays using x-ray scattering
- 2019
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Ingår i: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 92
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Konferensbidrag (refereegranskat)abstract
- X-ray scattering is a promising non-invasive technique to study evolving nano- and micro-mechanics in clays. This study discusses the experimental considerations and a successful method to enable X-ray scattering to study clay samples at two extreme stages of consolidation. It is shown that the proposed sample environment comprising flat capillaries with a hydrophobic coating can be used for a wide range of voids ratios ranging from a clay suspension to consolidated clay samples, that are cut from larger specimens of reconstituted or natural clay. The initial X-ray scattering results using a laboratory instrument indicate that valuable information on, in principal evolving, clay fabric can be measured. Features such as characteristic distance between structural units and particle orientations are obtained for a slurry and a consolidated sample of kaolinite. Combined with other promising measurement techniques from Materials Science the proposed method will help advance the contemporary understanding on the behaviour of dense colloidal systems of clay, as it does not require detrimental sample preparation.
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| 6. |
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| 7. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Atmospheric Corrosion of Mg Alloy AZ91D Fabricated by aSemi-Solid Casting Technique: The Influence of Microstructure
- 2015
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 162:7, s. C311-C321
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Tidskriftsartikel (refereegranskat)abstract
- The atmospheric corrosion behavior of alloy AZ91D produced by a semi-solid metal (SSM) technique and by conventional high pressure die casting (HPDC) was investigated for up to 1176 hours in the laboratory. Alloy AZ91D in the SSM state was fabricated using a rheocasting (RC) technique in which the slurry was prepared by the RheoMetal process. Exposures were performed in 95% RH air at 22 and 4 degrees C. The RC alloy AZ91D exhibited significantly better corrosion resistance than the HPDC material at two temperatures studied. The effect of casting technology on corrosion is explained in terms of the microstructural differences between the materials. For example, the larger number density of cathodic beta phase particles in the HPDC material initially causes relatively rapid corrosion compared to the RC material. During later stages of corrosion, the more network-like beta phase particles in the RC alloy act as a corrosion barrier, further improving the relative corrosion resistance of the RC material.
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| 8. |
- Havsed, Kristian, et al.
(författare)
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Bacterial Composition and Metabolomics of Dental Plaque From Adolescents
- 2021
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Ingår i: Frontiers in Cellular and Infection Microbiology. - : Frontiers Media SA. - 2235-2988. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Supragingival dental plaque samples were collected from 40 Swedish adolescents, including 20 with caries lesions (CAR) and 20 caries-free (CF). Fresh plaque samples were subjected to an ex vivo acid tolerance (AT) test where the proportion of bacteria resistant to an acid shock was evaluated through confocal microscopy and live/dead staining, and the metabolites produced were quantified by 1H Nuclear Magnetic Resonance (1H NMR). In addition, DNA was extracted and the 16S rRNA gene was sequenced by Illumina sequencing, in order to characterize bacterial composition in the same samples. There were no significant differences in AT scores between CAR and CF individuals. However, 7 out of the 10 individuals with highest AT scores belonged to the CAR group. Regarding bacterial composition, Abiotrophia, Prevotella and Veillonella were found at significantly higher levels in CAR individuals (p=0.0085, 0.026 and 0.04 respectively) and Rothia and Corynebacterium at significantly higher levels in CF individuals (p=0.026 and 0.003). The caries pathogen Streptococcus mutans was found at low frequencies and was absent in 60% of CAR individuals. Random-forest predictive models indicate that at least 4 bacterial species or 9 genera are needed to distinguish CAR from CF adolescents. The metabolomic profile obtained by NMR showed a significant clustering of organic acids with specific bacteria in CAR and/or high AT individuals, being Scardovia wiggsiae the species with strongest associations. A significant clustering of ethanol and isopropanol with health-associated bacteria such as Rothia or Corynebacterium was also found. Accordingly, several relationships involving these compounds like the Ethanol : Lactate or Succinate : Lactate ratios were significantly associated to acid tolerance and could be of predictive value for caries risk. We therefore propose that future caries risk studies would benefit from considering not only the use of multiple organisms as potential microbial biomarkers, but also their functional adaptation and metabolic output.
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| 9. |
- Jarfors, A. E. W., et al.
(författare)
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Microstructure formation of porous sintered Ti-Si-Zr compacts with mechanically alloyed-activated Ti-Si and TiH2 powders
- 2014
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 594, s. 202-210
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Tidskriftsartikel (refereegranskat)abstract
- Metallic implants are widely used in applications associated with bone. A major drawback of using metals is their elastic modulus which is higher than that of bone resulting in stress shielding and premature failure of the implant. The employment of biomaterials with a porous structure has the potential to lower the modulus and promote osseointegration. The present work investigates the microstructure formation and the resulting elastic modulus of a new Ti-Si-Zr alloy. The sintering procedure involves the use of both mechanically alloyed Ti-Si powder and TiH2 to activate sintering with the TiH2 also serving as a pore precursor. The procedure is designed to promote bonding but not consolidation. The influence of sintering temperature, heating rate, as well as the amount and size of the TiH2 on the phases formed and porosity was investigated. It was observed that the use of TiH2 increased the degree of porosity whilst the size of TiH2 particles could be used to control the pore size. The results showed that when using small TiH2 particles, the elastic modulus was strongly dependent on the fraction of TiH2. When large TiH2 particles were used, the porosity had no significant influence on the elastic modulus. The variation in behavior could be attributed to differences in microstructure. To control the bulk modulus it is essential to understand the differences in the microstructure formation mechanisms between these two cases. (C) 2014 Elsevier B.V. All rights reserved.
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| 10. |
- Kristensen, Brian K., et al.
(författare)
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Identification of oxidised proteins in the matrix of rice leaf mitochondria by immunoprecipitation and two-dimensional liquid chromatography-tandem mass spectrometry
- 2004
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Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 65:12, s. 1839-1851
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Tidskriftsartikel (refereegranskat)abstract
- Highly purified mitochondria were isolated from green 7-day-old rice leaves. The mitochondria were sonicated and the matrix fraction isolated as the 100,000g supernatant. Part of the matrix fraction was left untreated while the other part was subjected to a mild oxidative treatment (0.5 mM H2O2 + 0.2 mM CuSO4 for 10 min at room temperature). The oxidised proteins in both samples were tagged with dinitrophenylhydrazine (DNP), which forms a covalent bond with carbonyl groups. The DNP-tagged proteins were immunoprecipitated using anti-DNP antibodies and digested with trypsin. The mixture of peptides was analysed by nano-HPLC coupled online to an ESI-Quad-TOF mass spectrometer. The peptides were separated by stepwise ion exchange chromatography followed by reverse phase chromatography (2D-LC), and analysed by MS/MS. Proteins were identified by un-interpreted fragment ion database searches. Using this approach we identified 20 oxidised proteins in the control sample and a further 32 in the oxidised sample. Western blots of 2D-gels of the same samples prior to immunoprecipitation verified that the oxidation treatment increases protein oxidation also for specific proteins. Likewise Western blots showed that neither the isolation of mitochondria nor their subfractionation introduced carbonyl groups. We therefore conclude that a number of proteins are oxidised in the matrix of rice leaf mitochondria in vivo and further identify a group of proteins that are particularly susceptible to mild oxidation in vitro.
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