| 1. |
- Andersson, Bengt-Åke, et al.
(författare)
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Plasma tumor necrosis factor-α and C-reactive protein as biomarker for survival in head and neck squamous cell carcinoma.
- 2014
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Ingår i: Journal of Cancer Research and Clinical Oncology. - : Springer Science and Business Media LLC. - 0171-5216 .- 1432-1335. ; 140:3, s. 515-519
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Tumor TNM staging is the main basis for prognosis and treatment decision for head and neck squamous cell carcinoma (HNSCC) despite significant heterogeneity in terms of outcome among patients with the same clinical stage. In this study, a possible role of plasma interleukin-2 (IL-2), interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP) as biomarkers for survival of HNSCC patients was investigated.METHODS: In this prospective study, plasma levels of IL-2, IL-6, GM-CSF, TNF-α and CRP in patients (n = 100) and controls (n = 48) were analyzed.RESULTS: Significantly elevated levels of CRP and TNF-α (p < 0.001) were found in the patients. Combination of upregulated CRP and TNF-α in the patient plasma was significantly related to shorter patient survival, independent of clinical stage.CONCLUSIONS: Our findings indicate that CRP and TNF-α might be suitable as biomarkers in combination with tumor TNM staging for predicting survival and individualized treatment of HNSCC patients. Plasma CRP and TNF-α analysis are simple, rapid, cost effective and suitable for clinical practice.
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| 2. |
- Ekström, Erik, 1989-
(författare)
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Growth and thermoelectric properties of CaMnO3-based thin films
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The field of them1oelectrics started in early 19th century. Since the discovery of the Seebeck effect and the Peltier effect, thermoelectric modules have found their way into, mostly, niche applications such as radioisotope thermoelectric generators on space missions. Thermoelectric modules can also be used for cooling, utilizing the Peltier effect.Thermoelectrics are promising materials due to the operation nature of the modules. That is, they have no moving parts, no exhaust, long lifetime without maintenance, features that make them attractive for many applications. Despite these promising properties, thermoelectric modules are mostly used in niche applications. The main reason for this is conventional modules with the highest efficiency are commonly made of expensive and/or rare elements which prevents mass production.To tackle this problem, new materials are investigated to find a module that can be made widely available. Oxides are one possibility, where an added benefit is that they are chemically stable even at elevated temperature. The perovskite CaMnO3 is one of the more promising oxides, with elements that are abundant on earth and cheap. The material does suffer from low electrical conductivity which results in a low electrical conductivity and efficiency. A substantial effort has been put in to increase the efficiency of CaMnO3, hut it still needs improvement.In my thesis, I have investigated the CaMnO3 system. CaMnO3 was synthesized using co-reactive RF-magnetron sputtering and post annealing. The synthesis method is already known hut has not been used for deposition of perovskites. I have also demonstrated that this synthesis method can be used to dope CaMnO3 with niobium at appropriate levels for enhancing the efficiency.
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| 3. |
- Kumar, Ankit, et al.
(författare)
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Effect of in situ electric-field-assisted growth on antiphase boundaries in epitaxial Fe3O4 thin films on MgO
- 2018
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Ingår i: Physical Review Materials. - : American Physical Society. - 2475-9953. ; 2:5
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Tidskriftsartikel (refereegranskat)abstract
- Antiphase boundaries (APBs) normally form as a consequence of the initial growth conditions in all spinel ferrite thin films. These boundaries result from the intrinsic nucleation and growth mechanism, and are observed as regions where the periodicity of the crystalline lattice is disrupted. The presence of APBs in epitaxial films of the inverse spinel Fe3O4 alters their electronic and magnetic properties due to strong antiferromagnetic (AF) interactions across these boundaries. We explore the effect of using in-plane in situ electric-field-assisted growth on the formation of APBs in heteroepitaxial Fe3O4(100)/MgO(100) thin films. The electric-field-assisted growth is found to reduce the AF interactions across APBs and, as a consequence, APB-free thin-film-like properties are obtained, which have been probed by electronic, magnetic, and structural characterization. The electric field plays a critical role in controlling the density of APBs during the nucleation process by providing an electrostatic force acting on adatoms and therefore changing their kinetics. This innovative technique can be employed to grow epitaxial spinel thin films with controlled AF interactions across APBs.
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| 4. |
- Laytragoon-Lewin, Nongnit, et al.
(författare)
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Direct Effects of Pure Nicotine, Cigarette Smoke Extract, Swedish-type Smokeless Tobacco (Snus) Extract and Ethanol on Human Normal Endothelial Cells and Fibroblasts
- 2011
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 31:5, s. 1527-1534
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Tidskriftsartikel (refereegranskat)abstract
- The adverse health effects of cigarette smoking are well established including the increased risk of various types of cancer. In this study, the direct effects of ethanol, pure nicotine, cigarette smoke extract and Swedish type smokeless tobacco (Snus) extract on normal cells were investigated. Materials and Methods: Primary normal adult human endothelial cells and fibroblasts at early passage were used. Upon exposure to pure nicotine, cigarette smoke extract, Snus extract and ethanol, these cells were assessed for DNA synthesis, gene expression profile and cellular morphology. Results: Normal human fibroblasts and endothelial cells have unique gene expression profiles. The effects of treatment with ethanol and nicotine from different sources was more prominent in endothelial cells than fibroblasts. The combination of alterated gene expressions and strongly inhibited DNA synthesis was only detected in cells exposed to smoke extract. In the presence and absence of ethanol, pure nicotine and Snus extract induced abnormalities in the cytoplasm without any significant degree of cell death. With similar doses of nicotine and ethanol, the additional components in smoke extract had a dominant effect. The smoke extract induced vast cellular abnormalities and massive cell death. Conclusion: Cigarette smoke induced massive cell death and various abnormalities at cellular and molecular levels in surviving endothelial cells and fibroblasts. The combination of genomic alterations and the chronic inflammatory microenvironment induced from massive cell death, will potentially promote tumourigenesis and various diseases in cigarette smokers.
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| 5. |
- Laytragoon-Lewin, Nongnit, et al.
(författare)
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DNA Content and Methylation of p16, DAPK and RASSF1A Gene in Tumour and Distant, Normal Mucosal Tissue of Head and Neck Squamous Cell Carcinoma Patients
- 2010
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 30:11, s. 4643-4648
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Tidskriftsartikel (refereegranskat)abstract
- Long-term survival of head and neck squamous cell carcinoma (HNSCC) patients has not improved significantly during the last 20 years and recurrent disease is frequently observed. In this study, the potential presence of pre-malignant cells or rare malignant cells at the time of diagnosis in HNSCC was investigated. Patients and Methods: Fifty-nine biopsies obtained from 41 HNSCC patients were analysed. Eighteen of these biopsies were normal mucosal tissue, located at least 5 cm from the tumour margin. DNA content and DNA methylation of p16, DAPK and RASSF1A was examined. Results: Thirty-nine out of 41 (95%) tumour biopsies showed p16 methylation and 21 (51%) of them displayed aneuploidy. Of 18 distant normal mucosal biopsies, 6 (33%) of these showed evidence of aneuploidy and 15(83%) of them showed methylated p16 genes. Among paired samples, the highest frequencies of DNA methylation were found in tumours with aneuploidy. Regardless of DNA content, methylation at DAPK, RASSF1A or p16 were found in the corresponding distant mucosal biopsies. Conclusion: The cells with abnormal DNA content or DNA methylation in mucosal tissue were not detected clinically or by pathological macroscopic and microscopic examination. Thus, distant mucosal tissue DNA content and DNA methylation analyses in combination with histopathology will provide a better prognostic base for the evaluation and treatment of HNSCC patients.
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| 6. |
- Laytragoon-Lewin, Nongnit, et al.
(författare)
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Perforin, CD28 and CD95 expression in circulating CD4 and CD8 cells as predictors of head and neck (H&N) cancer patient survival
- 2014
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Ingår i: Medical Oncology. - : Springer Science and Business Media LLC. - 1357-0560 .- 1559-131X. ; 31:12, s. 290-
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Tidskriftsartikel (refereegranskat)abstract
- Long-term survival of H&N cancer patients has not improved significantly over the last 30 years. The possibility of using circulating blood cell phenotypes as a prognostic biomarker of H&N cancer patient was investigated in this study. Pre-treatment, circulating T lymphocyte subpopulations as well as the survival time of the patients in question were studied. Upregulated CD4+ perforin+ and CD8+ CD95+ but downregulated CD4+ CD28+ (p < 0.001) were detected in H&N cancer patients. With 3 years of follow-up time, an increase in the frequency of the pre-treatment, circulating CD4+ perforin+ cells and CD8+ perforin+ cells was showed to have reverse effects on the survival time in H&N cancer patients (p < 0.01). Detection of perforin? frequency in CD4+ and CD8+ lymphocyte by FACS is fast, simple and cost-effective. A potential role of perforin expression in CD4+ and CD8+ cells as a prognostic biomarker for H&N cancer patient in the clinical setting was suggested.
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| 7. |
- Lewin, Erik, et al.
(författare)
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Industrialisation Study of Nanocomposite nc-TiC/a-C Coatings for Electrical Contact Applications
- 2009
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Ingår i: Plasma Processes and Polymers. - : WILEY-VCH Verlag GmbH & Co. - 1612-8850. ; 6:S1, s. S928-S934
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Tidskriftsartikel (refereegranskat)abstract
- 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).
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| 8. |
- Lewin, N. L., et al.
(författare)
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Influence of single nucleotide polymorphisms among cigarette smoking and non-smoking patients with coronary artery disease, urinary bladder cancer and lung cancer
- 2021
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Cigarette smoke is suggested to be a risk factor for coronary artery disease (CAD), urinary bladder cancer (UBCa) or lung cancer (LCa). However, not all heavy smokers develop these diseases and elevated cancer risk among first-degree relatives suggests an important role of genetic factor. Methods Three hundred and ten healthy blood donors (controls), 98 CAD, 74 UBCa and 38 LCa patients were included in this pilot study. The influence of 92 single nucleotide polymorphisms (SNPs) and impact of cigarette smoking were analysed. Results Out of 92 SNPs tested, differences in distribution of 14 SNPs were detected between controls and patient groups. Only CTLA4 rs3087243 showed difference in both CAD and UBCa patient group compared to control group. Stratified by smoking status, the impact of smoking was associated to frequencies of 8, 3 and 4 SNPs in CAD, UBCa, LCa patients, respectively. None of these 92 SNPs showed a statistically significant difference to more than one type of disease among smoking patients. In non-smoking patients, 7, 3 and 6 SNPs were associated to CAD, UBCa, LCa, respectively. Out of these 92 SNPs, CTLA4 rs3087243 was associated to both non-smoking CAD and UBCa. The XRCC1 rs25487 was associated to both non-smoking UBCa and LCa. Conclusion SNPs might be important risk factors for CAD, UBCa and LCa. Distribution of the SNPs was specific for each patient group, not a random event. Impact of cigarette smoking on the disease was associated to the specific SNP sequences. Thus, smoking individuals with SNPs associated to risk of these serious diseases is an important target group for smoking cessation programs.
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| 9. |
- Lewin, Nongnit, et al.
(författare)
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Single Nucleotide Polymorphism and Cancer Risk, Tumour Recurrence, or Survival of Head and Neck Cancer Patients
- 2017
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Ingår i: Oncology. - : S. Karger AG. - 0030-2414 .- 1423-0232. ; 92, s. 161-169
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This paper aims at studying the influence of single-nucleotide polymorphisms (SNPs) on cancer risk, tumor recurrence, and survival in head and neck (H&N) cancer patients. Methods: A total of 45 SNPs in 41 genes were investigated. A total of 174 Caucasian H&N cancer patients and 245 healthy blood donors were enrolled in the study. Results: Ten SNPs were associated with H&N cancer risk, but the identified SNPs differed among males and females. Some of the SNPs were related to immune response genes. The immune response gene SNPs were also related to survival. In particular, we noted that the tumor necrosis factor alpha (TNFα) rs1800629 could have an influence on cancer risk, tumor recurrence as well as survival. Conclusion: Genetic variation of the TNFα rs1800629 might be useful as a biomarker in clinical decision-making since it was found to be related to cancer risk, tumor recurrence, and survival of H&N cancer patients.
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| 10. |
- Lewin, Nongnit, et al.
(författare)
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The Influence of Adjuvant Radiotherapy and Single Nucleotide Polymorphisms on Circulating Immune Response Cell Numbers and Phenotypes of Patients With Breast Cancer
- 2019
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Ingår i: Anticancer Research. - : INT INST ANTICANCER RESEARCH. - 0250-7005 .- 1791-7530. ; 39:9, s. 4957-4963
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aim: Adjuvant radiotherapy (RT) damages multiple layers of skin, muscle, blood vessels and blood cells that are included within the RT area. Indirect, bystander systemic effects could also develop in cells not directly hit by radiation. Materials and Methods: Ninety-three female patients recovering from breast cancer surgery and 82 female healthy blood donors were analyzed. For identification of systemic adaptive and innate immune response, rapid and low-cost blood-based biomarkers were assayed. Results: Post-operated breast cancer patients had a decreased number of circulating adaptive immune response cells but increased number of circulating immunosuppressive myeloid subpopulations. RT decreased the number of T-cells and platelets without influencing the number of immunosuppressive myeloid subpopulations. Alterations in the number and phenotypes of T-cell subpopulations were associated with SNPs. Conclusion: The combination of RT and immunotherapy might provide optimal treatment for cancer patients.
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| 11. |
- Lewin, Nongnit, et al.
(författare)
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The Influence of Single Nucleotide Polymorphisms and Adjuvant Radiotherapy on Systemic Inflammatory Proteins, Chemokines and Cytokines of Patients With Breast Cancer
- 2019
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Ingår i: Anticancer Research. - : INT INST ANTICANCER RESEARCH. - 0250-7005 .- 1791-7530. ; 39:3, s. 1287-1292
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Tidskriftsartikel (refereegranskat)abstract
- Independently of tumour and treatment modulation, the host immune response status plays an important role in the clinical outcome of patients with cancer. The influence of single nucleotide polymorphisms (SNPs) and adjuvant radiotherapy (RT) on the systemic immune response status of patients with breast cancer was investigated. Materials and Methods: Eighty-six female patients recovering from breast cancer surgery were investigated. As a control cohort, 82 healthy female blood donors were used. Blood-based SNPs, plasma C-reactive protein (CRP), cytokines and chemokines were analyzed for this purpose. Results: Independently of tumour stage and hormone receptor status, dysregulation of plasma CRP, chemokine (C-C motif) ligand 4 (CCL4) and interleukin 2 (IL2), but not CCL5, CCL2, platelet-derived growth factor, IL6, IL10, IL12, interferon-gamma or tumour necrosis factor alpha were detected in the patients when compared to controls. The extent of alteration in plasma levels of CRP and IL2 patients was significantly associated with SNPs in CRP rs1800947 and IL2 rs6822844, respectively. These SNPs had no influence on the levels of corresponding plasma biomarkers in the healthy controls. Adjuvant RT reduced plasma CRP and CCL5 levels in patients with regards to CRP rs1800947CC, CCL5 rs2107538GG and CCL5 rs2280789AA sequences. Conclusion: Dysregulation of immune responses, as indicated by plasma levels of CRP, CCL4 and IL2 were found in patients with breast cancer despite the removal of the tumour mass. The benefit of adjuvant RT, as indicated by reduced plasma amounts of inflammatory protein CRP and chemokine CCL5 were based on the SNPs of the patients. Analyses of blood-based SNPs, plasma CRP, IL2 and CCL5 are low cost, rapid and can be carried out using general laboratory facilities while requiring only a peripheral blood sample. The possibility of using these blood-based biomarkers as an indicator of patient immune status for selection of individual patient treatment warrants further investigation.
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| 12. |
- Lewin, Nongnit, et al.
(författare)
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The use of rapid and cost-effective blood-based biomarkers in combination with tumour TNM stage for individual head and neck cancer patient treatment selection
- 2017
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Ingår i: Medical Oncology. - : HUMANA PRESS INC. - 1357-0560 .- 1559-131X. ; 34:4
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Forskningsöversikt (refereegranskat)abstract
- Head and neck (Hamp;N) cancer is an aggressive disease and the incidence has increased in younger population worldwide. Tumour TNM staging is the main basis for treatment decision despite significant variation in clinical outcome. Survival time of these patients has marginally improved during the last 30 years. Various biomarkers with cumbersome analysis, high cost, time consumption and requirement of special laboratory facilities have been investigated. However, none of these biomarkers have been shown to be suitable to use for individual Hamp;N cancer patient treatment selection in the clinic. For practical use in clinical settings, the given biomarkers must be simple to analyse, rapid, cost effective and available in routine laboratories. With this intension, we suggested the combination of standard TNM staging and biomarkers associated with inflammation such as neutrophils, neutrophil to lymphocyte ratio, plasma C-reactive protein or plasma tumour necrosis factor alpha (TNFa) and single-nucleotide polymorphism in TNFa rs1800629 using blood-based analysis. The optimal treatment outcome of Hamp;N cancer by using combination of TNM stage and these blood-based biomarkers for individual patient selection need further investigation.
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| 13. |
- Alfakes, Boulos, et al.
(författare)
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Enhanced photoelectrochemical performance of atomic layer deposited Hf-doped ZnO
- 2020
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 385
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Tidskriftsartikel (refereegranskat)abstract
- Generation of hydrogen using photoelectrochemical (PEC) water splitting has attracted researchers for the last two decades. Several materials have been utilized as a photoanode in a water splitting cell, including ZnO due to its abundance, low production cost and suitable electronic structure. Most research attempts focused on doping ZnO to tailor its properties for a specific application. In this work, atomic layer deposition (ALD) was used to precisely dope ZnO with hafnium (Hf) in order to enhance its PEC performance. The resultant doped materials showed a significant improvement in PEC efficiency compared to pristine ZnO, which is linked directly to Hf introduction revealed by detailed optical, structural and electrical analyses. The photocurrent obtained in the best performing Hf-doped sample (0.75 wt% Hf) was roughly threefold higher compared to the undoped ZnO. Electrochemical impedance spectroscopy (EIS) and open-circuit potential-decay (OCPD) measurements confirmed suppression in photocarriers' surface recombination in the doped films, which led to a more efficient PEC water oxidation. The enhanced PEC performance of Hf-doped ZnO and effectiveness of the used metal dopant are credited to the synergistic optimization of chemical composition, which enhanced the electrical, structural including morphological, and optical properties of the final material, making Hf-doping an attractive candidate for novel PEC electrodes.
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| 14. |
- Andersson, Bengt-Åke, et al.
(författare)
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Cigarette smoking affects microRNAs and inflammatory biomarkers in healthy individuals and an association to single nucleotide polymorphisms is indicated
- 2019
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Ingår i: Biomarkers. - : Taylor & Francis. - 1354-750X .- 1366-5804. ; 24:2, s. 180-185
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cigarette smoke induces inflammation and remodels immune response. Genetic and epigenetic alterations might be involved in the pathogenesis of smoking related diseases. In this study, we investigated the effect of smoking on systemic inflammation biomarkers and epigenetic changes at microRNA (miRNA) expression level. We also examined if the levels of inflammatory biomarkers were associated with selected single nucleotide polymorphisms (SNPs).METHOD: From 39 smokers and 101 non-smokers, levels of total white blood cells (WBCs) and its subpopulations, plasma cytokines/chemokines/proteins and miRNAs were analysed. For three biomarkers, C-reactive protein (CRP), MCP-1 and IFN-γ that were affected by smoking, the influence of SNPs was analyzed.RESULT: Elevated levels of total WBCs, neutrophils, monocytes, lymphocytes, CRP, MCP-1, IFN-γ and lower levels of miR-21 were detected in smokers. The elevated levels of IFN-γ in smokers was only statistically significantly associated with rs2069705 AG/GG SNP-genotype.CONCLUSIONS: A lower level of oncomir miRNA-21 and a higher level of immune modelling cytokine IFN-γ detected in smokers could be a protective immune response to cigarette smoke. The higher level of IFN-γ in smokers with a specific SNP genotype also suggests that a genetic interaction with smoking might predict the pathobiology of smoking related disease.
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| 15. |
- Andersson, Matilda, et al.
(författare)
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Magnetron sputtering of Zr-Si-C thin films
- 2012
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 520:20, s. 6375-6381
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Tidskriftsartikel (refereegranskat)abstract
- The phase composition and chemical bonding of Zr-C and Zr-Si-C films deposited by magnetron sputtering has been studied. The results show that the binary Zr-C films at higher carbon contents form nanocrystallites of ZrC in an amorphous carbon matrix. The addition of Si induces a complete amorphization of the films above a critical concentration of about 15 at.%. X-ray diffraction and transmission electron microscopy confirm that the amorphous films contain no nanocrystallites and therefore can be described as truly amorphous carbides. The amorphous films are thermally stable but start to crystallize above 500 degrees C. Analysis of the chemical bonding with X-ray photoelectron spectroscopy suggests that the amorphous films exhibit a mixture of different chemical bonds such as Zr-C, Zr-Si and Si-C and that the electrical and mechanical properties are dependent on the distribution of these bonds. For higher carbon contents, strong Si-C bonds are formed in the amorphous Zr-Si-C films making them harder than the corresponding binary Zr-C films.
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| 16. |
- André, Benny, et al.
(författare)
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Friction and contact resistance of nanocomposite Ti-Ni-C coatings
- 2011
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 270:9-10, s. 555-566
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic nanocomposite coatings in the Ti-Ni-C were deposited using PVD and studied with respect to tribological properties and contact resistance. It was shown that coatings could be deposited combining of a low contact resistance and a low friction coefficient against silver, making them suitable for use in high performance electrical contacts.Nine coatings with different amounts of C and Ni were deposited. Coatings on flat Ni plated copper substrates were tested in a tribological ball-on-disc setup against ball bearing steel balls. Depending on primarily the amount of carbon the coatings showed very different friction coefficient and wear rate. The coatings were also deposited on cylindrical Ni plated copper substrates. Using geometrically identical silver plated cylinders as counter surface these were evaluated in a test setup better resembling a real life electrical contact. For most coatings a low electrical contact resistance was measured. The evolution of friction coefficient and contact resistance was correlated to wear marks and contact tracks, with their generated tribofilms, as examined after testing using electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy.
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| 17. |
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| 18. |
- Barbe, Laurent, et al.
(författare)
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Toward a confocal subcellular atlas of the human proteome
- 2008
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Ingår i: Molecular and cellular proteomics. - 1535-9476 .- 1535-9484. ; 7:3, s. 499-508
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Tidskriftsartikel (refereegranskat)abstract
- Information on protein localization on the subcellular level is important to map and characterize the proteome and to better understand cellular functions of proteins. Here we report on a pilot study of 466 proteins in three human cell lines aimed to allow large scale confocal microscopy analysis using protein-specific antibodies. Approximately 3000 high resolution images were generated, and more than 80% of the analyzed proteins could be classified in one or multiple subcellular compartment(s). The localizations of the proteins showed, in many cases, good agreement with the Gene Ontology localization prediction model. This is the first large scale antibody-based study to localize proteins into subcellular compartments using antibodies and confocal microscopy. The results suggest that this approach might be a valuable tool in conjunction with predictive models for protein localization.
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| 19. |
- Barker, Paul Michael, et al.
(författare)
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An investigation of c-HiPIMS discharges during titanium deposition
- 2014
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 258, s. 631-638
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Tidskriftsartikel (refereegranskat)abstract
- Abstract A modified version of high power impulse magnetron sputtering (HiPIMS) has been used to deposit titanium films at higher deposition rates than for conventional HiPIMS whilst maintaining similar pulse voltages and peak currents. This process, named chopped-HiPIMS (c-HiPIMS) utilises pulses decomposed into several short single pulses instead of single HiPIMS pulses. Experiments show that manipulating the pulse sequence during c-HiPIMS, i.e. the tÎŒon and tÎŒoff times (explained in the glossary) allows for an increase of the deposition rate; increases of up to 150% are reported here for selected conditions. Further, deposition rates higher than those measured using direct current magnetron sputtering are also shown. Investigations by optical emission and optical absorption spectroscopy at the substrate show that the increase of deposition rate is not a consequence of different ion concentrations arriving at the substrate when changing the micro-pulse-off times of c-HiPIMS. Thus alternative reasons for the enhanced deposition rate during c-HiPIMS deposition of metal films are discussed. It is demonstrated that film micro-structure maintains the void free, dense nature typically demonstrated by HiPIMS deposited coatings whilst at enhanced deposition rates. Thus c-HiPIMS allows for the preparation of dense films with the benefit of faster growth rates.
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| 20. |
- Barker, Paul Michael, et al.
(författare)
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Modified high power impulse magnetron sputtering process for increased deposition rate of titanium
- 2013
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 31:6, s. 060604-
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Tidskriftsartikel (refereegranskat)abstract
- A modified version of high power impulse magnetron sputtering (HiPIMS) has been used to deposit titanium films at higher deposition rates than for conventional HiPIMS while maintaining similar pulse voltages and peak currents. In the present study, additional control parameters are explored through the chopping of the HiPIMS pulse into a pulse sequence. Experiments show that the use of sequences allows for an increase of the deposition rate of more than 45% compared to conventional HiPIMS. The increase in deposition rate is ascribed to a combination of reduced gas rarefaction effects, prevention of sustained self-sputtering, and a relaxation of ion trapping.
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| 21. |
- Bijelovic, Stojanka, et al.
(författare)
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Wear-resistant magnetic thin film material based on a Ti1−xFexC1−y nanocomposite alloy
- 2010
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Ingår i: Physical Review B Condensed Matter. - : The American Physical Society. - 0163-1829 .- 1095-3795. ; 81:1, s. 014405-
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Tidskriftsartikel (refereegranskat)abstract
- In this study we report on the film growth and characterization of thin films deposited on amorphous quartz. The experimental studies have been complemented by first-principles density-functional theory metastable Ti-Fe-C film changes. With increasing annealing time, there is a depletion of iron close to the surface of the film, while regions enriched in iron are simultaneously formed deeper into the film. Both the magnetic ordering temperature and the saturation magnetization changes significantly upon annealing. The DFT calculations show that the critical temperature and the magnetic moment both increase with increasing Fe and C-vacancy concentration. The formation of the metastable iron-rich Ti-Fe-C compound is reflected in the strong increase in the magnetic ordering temperature. Eventually, after enough annealing time nanocrystalline -Fe starts to precipitate, the amount and size of which can be controlled by the annealing procedure; after 20 min of annealing, the experimental results indicate a nanocrystalline iron-film embedded in a wear-resistant TiC compound. This conclusion is further supported by transmission electron microscopy studies on epitaxial Ti-Fe-C films deposited on single-crystalline MgO substrates where, upon annealing, an iron film embedded in TiC is formed. Our results suggest that annealing of metastable Ti-Fe-C films can be used as an efficient way of creating a wear-resistant magnetic thin film material. approximately 50-nm-thick Ti-Fe-CDFT calculations. Upon annealing of as-prepared films, the composition of the10 min, nanocrystalline -Fe starts to precipitate, the amount and size of which can be controlled by the annealing procedure; after 20 min of annealing, the experimental results indicate a nanocrystalline iron-film embedded in a wear-resistant TiC compound. This conclusion is further supported by transmission electron microscopy studies on epitaxial Ti-Fe-C films deposited on single-crystalline MgO substrates where, upon annealing, an iron film embedded in TiC is formed. Our results suggest that annealing of metastable Ti-Fe-C films can be used as an efficient way of creating a wear-resistant magnetic thin film material.
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| 22. |
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| 23. |
- Bottger, P. H. M., et al.
(författare)
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Hard wear-resistant coatings with anisotropic thermal conductivity for high thermal load applications
- 2014
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 116:1, s. 013507-
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Tidskriftsartikel (refereegranskat)abstract
- High thermal load applications such as high speed dry cutting lead to high temperatures in the coated tool substrate that can soften the tool and high temperature gradients that can put stress on the coating/tool interface. In this work, theoretical considerations are presented for multilayer and graded protective coatings that can induce a significant anisotropy in their thermal conductivity. Solution of the heat equation shows that anisotropy of thermal conductivity has the potential to reduce temperatures and temperature gradients arising due to brief, localized heat at the coating surface ("hot-spots"). Experimental realization of high anisotropy is demonstrated in TiN/AlCrN multilayer coatings with variable layer thickness. In the coating with 50 nm bilayer periodicity, the highest anisotropy was obtained with a value of kappa(parallel to)/kappa(perpendicular to) = 3.0 +/- 0.9. Time-domain thermoreflectance is used to measure in-plane and cross-plane thermal conductivity of fabricated coatings. The observed high values of anisotropy of thermal conductivity are compared with theoretical predictions and its realisation is discussed with regard to the coating microstructure.
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| 24. |
- Casillas Trujillo, Luis, et al.
(författare)
-
Experimental and theoretical evidence of charge transfer in multi-component alloys : how chemical interactions reduce atomic size mismatch
- 2021
-
Ingår i: Materials Chemistry Frontiers. - : Royal Society of Chemistry. - 2052-1537. ; 5:15, s. 5746-5759
-
Tidskriftsartikel (refereegranskat)abstract
- Ab initio simulations of a multi-component alloy using density functional theory (DFT) were combined with experiments on thin films of the same material using X-ray photoelectron spectroscopy (XPS) to study the connection between the electronic and atomic structures of multi-component alloys. The DFT simulations were performed on an equimolar HfNbTiVZr multi-component alloy. Structure and charge transfer were evaluated using relaxed, non-relaxed, as well as elemental reference structures. The use of a fixed sphere size model allowed quantification of charge transfer, and separation into different contributions. The charge transfer was generally found to follow electronegativity trends and results in a reduced size mismatch between the elements, and thus causes a considerable reduction of the lattice distortions compared to a traditional assumption based on tabulated atomic radii. A calculation of the average deviation from the average radius (i.e. the so-called δ-parameter) based on the atomic Voronoi volumes gave a reduction of δ from ca. 6% (using the volumes in elemental reference phases) to ca. 2% (using the volumes in the relaxed multi-component alloy phase). The reliability of the theoretical results was confirmed by XPS measurements of a Hf22Nb19Ti18V19Zr21 thin film deposited by sputter deposition. The experimentally observed core level binding energy shifts (CLS), as well as peak broadening due to a range of chemical surroundings, for each element showed good agreement with the calculated DFT values. The single solid solution phase of the sample was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) including energy dispersive spectroscopy (EDS) with nm-resolution. These observations show that the HfNbTiVZr solid solution phase is non-ideal, and that chemical bonding plays an important part in the structure formation, and presumably also in the properties. Our conclusions should be transferable to other multi-component alloy systems, as well as some other multi-component material systems, and open up interesting possibilities for the design of material properties via the electronic structure and controlled charge transfer between selected metallic elements in the materials.
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| 25. |
- Cederblad, Lena, et al.
(författare)
-
The Combined Effects of Single-Nucleotide Polymorphisms, Tobacco Products, and Ethanol on Normal Resting Blood Mononuclear Cells
- 2013
-
Ingår i: Nicotine & tobacco research. - : Oxford University Press (OUP). - 1462-2203 .- 1469-994X. ; 15:5, s. 890-895
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Tobacco and ethanol consumption are crucial factors in the development of various diseases including cancer. In this investigation, we evaluated the combined effects of a number of single nucleotide polymorphisms (SNPs), with ethanol and tobacco products on healthy individuals. Methods: Pure nicotine, cigarette smoke extract, and Swedish snuff (snus) extract were used. The effects were examined by means of in vitro cell cycle progression and cell death of peripheral blood mononuclear cells (PBMCs) obtained from healthy donors. Results: After 3 days, in vitro, resting PBMCs entered the S and G2 stage in the presence of 100 mu M nicotine. The PBMCs only proceeded to S stage, in the presence of 0.2% ethanol. The nicotine- and ethanol-induced normal cell cycle progression correlated to a number of SNPs in the IL12RB2, Rad 52, XRCC2, P53, CCND3, and ABCA1 genes. Certain SNPs in Caspases 8, IL12RB2, Rad 52, MMP2, and MDM2 genes appeared to significantly influence the effects of EtOH-, snus-, and snus + EtOH-induced cell death. Importantly, the highest degree of cell death was observed in the presence of smoke + EtOH. The amount of cell death under this treatment condition also correlated to specific SNPs, located in the MDM2, ABCA1, or GASC1 genes. Conclusions: Cigarette smoke in combination with ethanol strongly induced massive cell death. Long-term exposure to smoke and ethanol could provoke chronic inflammation, and this could be the initiation of disease including the development of cancer at various sites.
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| 26. |
- Cedervall, Johan, et al.
(författare)
-
On the structural and magnetic properties of the double perovskite Nd2NiMnO6Nd2NiMnO6
- 2019
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 30:17, s. 16571-16578
-
Tidskriftsartikel (refereegranskat)abstract
- The structural, electronic and magnetic properties of phase pure and stoichiometric samples of the double perovskite Nd 2NiMnO 6 have been investigated with a combination of X-ray and neutron diffraction, X-ray photoelectron spectroscopy and magnetometry. It is found that the monoclinic space group P2 1/ n best describes the crystal structure of Nd 2NiMnO 6. Photoectron spectroscopy revels a mixed valence of the transition metal sites where Ni has 3+/2+ oxidation states and Mn has 3+/4+. The compound orders ferromagnetically at ∼195 K. The magnetic structure was determined from the refinement of the neutron diffraction data. The results suggests that the B-site magnetic moments align along the crystallographic a-direction.
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| 27. |
- Fernandes, Arthur B., et al.
(författare)
-
Recoverable and Reusable Polymer Microbead-Supported Metal Nanocatalysts for Redox Chemical Transformations
- 2020
-
Ingår i: ACS APPLIED NANO MATERIALS. - : AMER CHEMICAL SOC. - 2574-0970. ; 3:2, s. 1722-1730
-
Tidskriftsartikel (refereegranskat)abstract
- Metal nanoparticles have been widely exploited in catalysis, but their full impact on the environment and human health is still under debate. Here we describe the one-step fabrication of recoverable and reusable polymer microbead-supported metal and metal oxide nanocatalysts for application in batch reactions and flow systems. Au, Ag, and Fe3O4 nanoparticles were prepared directly at the surface of commercial benzylamine-coated spherical polymer beads in water by using low-energy microwave radiation for 5 min. The functionalization of microbead surface with betalamic acid, an antioxidant from plant origin, before irradiation changes the morphology and catalytic properties of the grafted nanoparticles. No leaching of the active phase was observed during the application of these effective and ready-to-use nanocatalysts on the reduction of 4-nitrophenol and oxidation of dihydrorhodamine 123. The supported nanocatalysts were recovered by filtration and/or magnetic separation and reused up to three times without significant drop in catalytic performance. These results can stimulate the controlled and facile synthesis of recoverable microbead-supported magnetic and nonmagnetic nanocatalysts that can be applied under myriad reaction conditions and reused multiple times.
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| 28. |
- Folkenant, Matilda, et al.
(författare)
-
Structure and properties of Cr–C/Ag films deposited by magnetron sputtering
- 2015
-
Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 281, s. 184-192
-
Tidskriftsartikel (refereegranskat)abstract
- Cr–C/Ag thin films with 0–14 at.% Ag have been deposited by magnetron sputtering from elemental targets. The samples were analyzed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to study their structure and chemical bonding. A complex nanocomposite structure consisting of three phases; nanocrystalline Ag, amorphous CrCx and amorphous carbon is reported. The carbon content in the amorphous carbide phase was determined to be 32–33 at.% C, independent of Ag content. Furthermore, SEM and XPS results showed higher amounts of Ag on the surface compared to the bulk. The hardness and Young's modulus were reduced from 12 to 8 GPa and from 270 to 170 GPa, respectively, with increasing Ag content. The contact resistance was found to decrease with Ag addition, with the most Ag rich sample approaching the values of an Ag reference sample. Initial tribological tests gave friction coefficients in the range of 0.3 to 0.5, with no clear trends. Annealing tests show that the material is stable after annealing at 500 °C for 1 h, but not after annealing at 800 °C for 1 h. In combination, these results suggest that sputtered Cr–C/Ag films could be potentially applicable for electric contact applications.
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| 29. |
- Folkenant, Matilda
(författare)
-
Synthesis and Characterization of Amorphous Carbide-based Thin Films
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, research on synthesis, structure and characterization of amorphous carbide-based thin films is presented. Crystalline and nanocomposite carbide films can exhibit properties such as high electrical conductivity, high hardness and low friction and wear. These properties are in many cases structure-related, and thus, within this thesis a special focus is put on how the amorphous structure influences the material properties.Thin films within the Zr-Si-C and Cr-C-based systems have been synthesized by magnetron sputtering from elemental targets. For the Zr-Si-C system, completely amorphous films were obtained for silicon contents of 20 at.% or higher. Modeling of these films, as well as experimental results suggest that the films exhibit a network-type structure where the bond types influence the material properties. Higher hardness and resistivity were observed with high amounts of covalent Si-C bonds.Several studies were performed in the Cr-C-based systems. Cr-C films deposited in a wide composition range and with substrate temperatures of up to 500 °C were found to be amorphous nanocomposites, consisting of amorphous chromium carbide (a-CrCx) and amorphous carbon (a-C) phases. The carbon content in the carbidic phase was determined to about 30-35 at.% for most films. The properties of the Cr-C films were very dependent of the amount of a-C phase, and both hardness and electrical resistivity decreased with increasing a-C contents. However, electrochemical analysis showed that Cr-C films deposited at higher substrate temperature and with high carbon content exhibited very high oxidation resistance. In addition, nanocomposite films containing Ag nanoparticles within an amorphous Cr-C matrix were studied in an attempt to improve the tribological properties. No such improvements were observed but the films exhibited a better contact resistance than the corresponding binary Cr-C films. Furthermore, electrochemical analyses showed that Ag nanoparticles on the surface affected the formation of a stable passive film, which would make the Cr-C/Ag films less resilient to oxidation than the pure Cr-C films.
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| 30. |
- Fritze, Stefan, et al.
(författare)
-
Elemental distribution and fracture properties of magnetron sputtered carbon supersaturated tungsten films
- 2024
-
Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 477
-
Tidskriftsartikel (refereegranskat)abstract
- The combination of strength and toughness is a major driving force for alloy design of protective coatings, and nanocrystalline tungsten (W)-alloys have shown to be promising candidates for combining strength and toughness. Here we investigate the elemental distribution and the fracture toughness of carbon (C) alloyed W thin films prepared by non-reactive magnetron sputtering. W:C films with up to ~4 at.% C crystallize in a body-centered-cubic structure with a strong 〈hh0〉texture, and no additional carbide phases are observed in the diffraction pattern. Atom probe tomography and X-ray photoelectron spectroscopy confirmed the formation of such a supersaturated solid solution. The pure W film has a hardness ~13 GPa and the W:C films exhibit a peak hardness of ~24 GPa. In-situ micromechanical cantilever bending tests show that the fracture toughness decreases from ~4.5 MPa·m1/2 for the W film to ~3.1 MPa·m1/2 for W:C films. The results show that C can significantly enhance the hardness of W thin films while retaining a high fracture toughness.
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| 31. |
- Fritze, Stefan, et al.
(författare)
-
Hard and crack resistant carbon supersaturated refractory nanostructured multicomponent coatings
- 2018
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- The combination of ceramic hardness with high crack resistance is a major challenge in the design of protective thin films. High entropy alloys have shown in earlier studies promising mechanical properties with a potential use as thin film materials. In this study, we show that small amounts of carbon in magnetron-sputtered multicomponent CrNbTaTiW films can lead to a significant increase in hardness. The film properties were strongly dependent on the metal composition and the most promising results were observed for TaW-rich films. They crystallised in a bcc structure with a strong (110) texture and coherent grain boundaries. It was possible to deposit films with 8 at.% C in a supersaturated solid-solution into the bcc structure without carbide formation. A major effect of carbon was a significant grain refinement, reducing the column diameter from approximately 35 to 10 nm. This resulted in an increase in hardness from 14.7 to 19.1 GPa while the reduced E-modulus stayed constant at 322 GPa. The carbon-containing films exhibited extremely little plastic deformation around the indent and no cracks were observed. These results show that supersaturation of carbon into high entropy films can be a promising concept to combine superior hardness with high crack resistance.
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| 32. |
- Fritze, Stefan, et al.
(författare)
-
Influence of Carbon on Microstructure and Mechanical Properties of Magnetron Sputtered TaW Coatings
- 2020
-
Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 196
-
Tidskriftsartikel (refereegranskat)abstract
- (Ta,W) and (Ta,W):C films with-5 at.% C were deposited by non-reactive magnetron sputtering. They crystallised in a bcc structure with a columnar microstructure. The solid solubility of C in (Ta,W) alloys is very low, which suggests that the (Ta,W):C films are supersaturated with respect to carbon. This was confirmed by diffraction and atom probe tomography (APT) showing that carbon is in the as-deposited (Ta,W):C films homogeneously distributed in the structure without carbide formation or carbon segregation. Annealing at 900 degrees C for 2 h showed no significant column coarsening but an increased defect density at the column boundaries in the (Ta,W):C films. The films were still supersaturated with respect to carbon but APT showed a partial segregation of carbon presumably to defect-rich column boundaries after annealing. The (Ta,W) films exhibited a hardness of-12-13 GPa. Alloying with carbon increased the hardness to-17 GPa. The hardness increased to-19 GPa for the annealed (Ta,W):C films. This annealing-induced hardness increase was explained by C segregation to the more defect-rich column boundaries, which restricts dislocation movements. (Ta,W):C coatings may be a potential alternative to ceramic coatings, worth exploring further by small scale mechanical testing to investigate if these materials are ductile.
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| 33. |
- Fritze, Stefan, et al.
(författare)
-
Influence of Deposition Temperature on the Phase Evolution of HfNbTiVZr High-Entropy Thin Films
- 2019
-
Ingår i: Materials. - : MDPI. - 1996-1944. ; 12:4
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, we show that the phase formation of HfNbTiVZr high-entropy thin films is strongly influenced by the substrate temperature. Films deposited at room temperature exhibit an amorphous microstructure and are 6.5 GPa hard. With increasing substrate temperature (room temperature to 275 degrees C), a transition from an amorphous to a single-phased body-centred cubic (bcc) solid solution occurs, resulting in a hardness increase to 7.9 GPa. A higher deposition temperature (450 degrees C) leads to the formation of C14 or C15 Laves phase precipitates in the bcc matrix and a further enhancement of mechanical properties with a peak hardness value of 9.2 GPa. These results also show that thin films follow different phase formation pathways compared to HfNbTiVZr bulk alloys.
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| 34. |
|
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| 35. |
- Fritze, Stefan, et al.
(författare)
-
Magnetron sputtering of carbon supersaturated tungsten films-A chemical approach to increase strength
- 2021
-
Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 208
-
Tidskriftsartikel (refereegranskat)abstract
- Tungsten (W)-based materials attract significant attention due to their superior mechanical properties. Here, we present a chemical approach based on the addition of carbon (C) for increased strength via the combination of three strengthening mechanisms in W thin films. W:C thin films with C concentrations up to-4 at.% were deposited by magnetron sputtering. All films exhibit a body-centred-cubic structure with strong texture and columnar growth behaviour. X-ray and electron diffraction measurements suggest the formation of supersaturated W:C solid solution phases. The addition of C reduced the average column width from-133 nm for W to-20 nm for the film containing-4 at.% C. The column refinement is explained by a mechanism where C acts as re-nucleation sites. The W film is-13 GPa hard, while the W:C films achieve a peak hardness of-24 GPa. The W:C films are-11 GPa harder than the W film, which is explained by a combination of grain refinement strengthening, solid solution strengthening and increased dislocation density. Additional micropillar compression tests showed that the flow stress increased upon C addition, from-3.8 to-8.3 GPa and no brittle fracture was observed.
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| 36. |
- Fritze, Stefan
(författare)
-
Microstructure and Mechanical Properties of Magnetron Sputtered Refractory Metal Thin Films
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The design and development of new multifunctional materials that exhibit a combination of high hardness and ductility, as well as a high corrosion resistance and thermal stability, is one of the key challenges in the field of material science. The focus of this thesis is on the development of novel multifunctional magnetron sputtered CrNbTaTiW–C based thin films. Carbon was selected as an alloying element to investigate if it could modify the microstructure (via grain refinement) and improve the properties (e.g. the hardness and ductility).TaW-rich and near-equimolar high entropy alloys in the CrNbTaTiW system were selected as starting points for this study. The latter alloys were predicted, based on empirical design rules, to form a single-phase solid solution. In contrast, thermodynamic calculations showed that the films at equilibrium should be composed of a mixture of several phases at temperatures below 1100 °C. Experimentally, however, a single-phase bcc structure was observed for the deposited films and it was concluded that the films were kinetically and not entropy stabilised. A hypothesis is that the kinetics during sputtering allow a ’direct’ phase selection by tuning the process parameters and evidence of this was found in the HfNbTiVZr alloy system.The CrNbTaTiW–C system is, however, complex and additional studies were carried out on the W–C and TaW–C systems. All metallic films crystallised in a bcc structure with a <110> texture and the column width of these films varied between 25 nm and 80 nm. The films were very hard (~ 13 GPa), which was explained by the small grain size. A single-phase bcc structure was also obtained upon the addition of 5-10 at.% carbon for all compositions except the near-equimolar CrNbTaTiW. X-ray diffraction indicated a unit cell expansion, which was attributed to the formation of a supersaturated solid solution. Additional atom probe tomography (APT) studies on selected samples confirmed the formation of such solid solutions. The supersaturated solid solution is not thermodynamically stable and an annealing study showed that heat treatment yielded segregation and clustering of carbon at the grain boundaries. The addition of carbon had a grain refining effect in the W–C system and the multicomponent CrNbTaTiW–C system. In general, the addition of carbon increased the hardness, which was mainly caused by a reduced grain size in line with the Hall-Petch relationship. Excellent mechanical properties of carbon supersaturated films were further confirmed in pillar tests on W–C films, which showed very high yield strength (~ 9 GPa) and no brittle fracture. The results show that carbon can be used as a chemical approach to control the grain size and properties of these films. Multicomponent carbides with a B1 structure were formed at high carbon concentrations (~ 40 at.%). The microstructure of these films depended strongly on the process parameters and a higher deposition temperature was found to increase the film density and hardness. The TaW-rich carbide exhibited a very high hardness of ~ 35 GPa and excellent corrosion resistance.
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| 37. |
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| 38. |
- Garlisi, Corrado, et al.
(författare)
-
N-TiO2/Cu-TiO2 double-layer films : Impact of stacking order on photocatalytic properties
- 2017
-
Ingår i: Journal of Catalysis. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0021-9517 .- 1090-2694. ; 353, s. 116-122
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we report for the first time a unique configuration of N-doped and Cu-doped TiO2 bilayer. The activity of TiO2 was improved by combining Cu- and N-doping in a layered thin-film structure. The impact of the stacking order was studied, pointing out how the best arrangement is by far the one with Cu-TiO2 as the top layer. The results reveal a unique and simple way to enhance the photocatalytic response of TiO2 in the visible domain.
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| 39. |
- Gaulton, Kyle J, et al.
(författare)
-
Genetic fine mapping and genomic annotation defines causal mechanisms at type 2 diabetes susceptibility loci.
- 2015
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 47:12, s. 1415-1415
-
Tidskriftsartikel (refereegranskat)abstract
- We performed fine mapping of 39 established type 2 diabetes (T2D) loci in 27,206 cases and 57,574 controls of European ancestry. We identified 49 distinct association signals at these loci, including five mapping in or near KCNQ1. 'Credible sets' of the variants most likely to drive each distinct signal mapped predominantly to noncoding sequence, implying that association with T2D is mediated through gene regulation. Credible set variants were enriched for overlap with FOXA2 chromatin immunoprecipitation binding sites in human islet and liver cells, including at MTNR1B, where fine mapping implicated rs10830963 as driving T2D association. We confirmed that the T2D risk allele for this SNP increases FOXA2-bound enhancer activity in islet- and liver-derived cells. We observed allele-specific differences in NEUROD1 binding in islet-derived cells, consistent with evidence that the T2D risk allele increases islet MTNR1B expression. Our study demonstrates how integration of genetic and genomic information can define molecular mechanisms through which variants underlying association signals exert their effects on disease.
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| 40. |
- Glechner, T., et al.
(författare)
-
Tuning structure and mechanical properties of Ta-C coatings by N-alloying and vacancy population
- 2018
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Tailoring mechanical properties of transition metal carbides by substituting carbon with nitrogen atoms is a highly interesting approach, as thereby the bonding state changes towards a more metallic like character and thus ductility can be increased. Based on ab initio calculations we could prove experimentally, that up to a nitrogen content of about 68% on the non-metallic sublattice, Ta-C-N crystals prevail a face centered cubic structure for sputter deposited thin films. The cubic structure is partly stabilized by non-metallic as well as Ta vacancies-the latter are decisive for nitrogen rich compositions. With increasing nitrogen content, the originally super-hard fcc-TaC0.71 thin films soften from 40 GPa to 26 GPa for TaC0.33N0.67, accompanied by a decrease of the indentation modulus. With increasing nitrogen on the non-metallic sublattice (hence, decreasing C) the damage tolerance of Ta-C based coatings increases, when characterized after the Pugh and Pettifor criteria. Consequently, varying the non-metallic sublattice population allows for an effective tuning and designing of intrinsic coating properties.
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| 41. |
- Greczynski, Grzegorz, et al.
(författare)
-
X-ray photoelectron spectroscopy of thin films
- 2023
-
Ingår i: NATURE REVIEWS METHODS PRIMERS. - : SPRINGERNATURE. - 2662-8449. ; 3:1
-
Tidskriftsartikel (refereegranskat)abstract
- X-ray photoelectron spectroscopy (XPS) is a popular analytical technique in materials science as it can assess the surface chemistry of a broad range of samples. This Primer concerns best practice in XPS analysis, aimed at both entry-level and advanced users, with a focus on thin film samples synthesized under vacuum conditions. The high surface to volume ratio of thin films means that factors such as substrate choice and air exposure time are important for the final result. Essential concepts are introduced, such as binding energy, photoelectric effect, spectral referencing and chemical shift, as well as practical aspects including surface sensitivity, probing depth, energy resolution, sample handling and sputter etching. Correct procedures for experimental planning, instrument set-up, sample preparation, data acquisition, results analysis and presentation are reviewed in connection with physical principles and common applications. Typical problems, including charging, spectral overlap, sputter damage and binding energy referencing, are discussed along with possible solutions or workarounds. Finally, a workflow is presented for arriving at high-quality results. X-ray photoelectron spectroscopy (XPS) can be used to investigate chemical bonding and elemental composition. This Primer discusses how XPS can be used to characterize thin films, including key considerations for sample preparation, experimental set-up and data analysis.
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| 42. |
- Hanifpour, Fatemeh, et al.
(författare)
-
Investigation into the mechanism of electrochemical nitrogen reduction reaction to ammonia using niobium oxynitride thin-film catalysts
- 2022
-
Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 403
-
Tidskriftsartikel (refereegranskat)abstract
- Niobium oxynitride (NbOxNy) thin films with varying combined non-metal vs. metal stoichiometries ( x + y ) and N/O stoichiometric ratios (y/x) are investigated for their ability to catalyze the nitrogen re-duction reaction and ammonia synthesis at ambient conditions. Electrochemical impedance spectroscopy and ammonia measurements show stark differences both in nitrogen vs. argon media on each surface and on the surfaces in the series when the combined stoichiometry of N + O vs. Nb increases. Surface stability checks at fixed intervals during the experiments and surface characterization after the experiments us -ing X-ray diffraction reveal the least changes occurred to the surface with the highest N + O stoichiometry. Based on these observations, an ammonia synthesis mechanism is proposed. Isotope labeling experiments on the most promising surface of the series, however, show no sign of catalytically produced ammonia, possibly due to the lack of stability of the surface to endure through the ammonia production cycle.
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| 43. |
- Hanifpour, Fatemeh, et al.
(författare)
-
Operando quantification of ammonia produced from computationally-derived transition metal nitride electro-catalysts
- 2022
-
Ingår i: Journal of Catalysis. - : Elsevier. - 0021-9517 .- 1090-2694. ; 413, s. 956-967
-
Tidskriftsartikel (refereegranskat)abstract
- Electrochemical reduction of dinitrogen to ammonia is investigated in a micro-reactor flow-cell using thin films of VN, CrN, NbN and ZrN. Chronoamperometry loops are used for ammonia production analysis. Operando ammonia quantification is accomplished in a flow injection analyzer. Results show the effect of presence/absence of N-2(g) within both the electrochemical characterization and ammonia production for ZrN. However, no ammonia is detected from studies on CrN. VN and NbN are inactivated upon reacting their N atoms of the surface top layer(s). Results obtained from ammonia measurements, electrochemical impedance spectroscopy analysis, surface stability checks, and surface characterization using X-ray reflectivity, reveal certain trends indicating catalytic behavior for ZrN. However, the concentration of produced ammonia is below the detection limit of the methods devised to analyze the samples from isotope labeling experiments. The onset of ammonia production on ZrN appears to be in close agreement with that predicted previously by computational studies.
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| 44. |
- Huang, Yu-Kai
(författare)
-
Advancements in Lithium-Based Batteries : Unraveling and Mitigating Performance-Limiting Phenomena in Negative Electrodes
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of lithium-based batteries, especially lithium-ion batteries, has changed our daily lives significantly. The technologies first enabled by lithium-based batteries are now in turn creating a demand for better lithium-based batteries with higher energy densities and longer cycling lifetimes. This requires studies and development of negative electrodes, with a particular focus on gaining a better and more complete understanding of all performance-limiting phenomena and to develop appropriate mitigation strategies.For negative electrodes based on alloy-forming materials such as silicon, aluminum and tin, it has, recently been shown that capacities losses can result from diffusion-controlled trapping of lithium due to an incomplete delithiation of the electrodes. In the first part of the thesis, it is demonstrated explicitly that such a lithium trapping effect also is seen for conventional graphite electrodes. This effect is further demonstrated to greatly affect the cycle life performance of NMC811/graphite full cells during high-rate cycling. However, it is also demonstrated that the inclusion of constant-voltage delithiation steps can increase the delithiation efficiency and decrease the influence of the trapping effect. The use of silicon electrodes based on silicon nanoparticles is also revisited. It is proposed that the influence of the lithium trapping effect seen for such electrodes is affected by the size of the employed silicon nanoparticles, most likely, via its influence on the electrode microstructure. Replacing the currently used negative electrodes with lithium-metal electrodes, especially in a “anode-free” configuration, can significantly increase the energy densities of lithium-based batteries due to the high capacity and low electrochemical potential of elemental lithium. However, the inhomogeneous lithium deposition and stripping greatly limit the cycling performance. In the second part of this thesis, strategies focusing on electrochemically controlling the nucleation and growth of lithium are proposed to improve the deposition of lithium on lithium-metal electrodes as well as directly on copper current collectors. In the former study, it is shown that forming a great number of homogeneously distributed nucleation sites across the entire electrode surface, via the introduction of a one-second long potentiostatic oxidation pulse, subsequently yields more homogeneous lithium deposition. In the second study, it is found that the nucleation of lithium on copper current collectors can be affected by the diffusion of lithium into the current collectors. It is also demonstrated that the influence of this effect can be decreased by chemically prelithiating the current collectors so that more homogeneous lithium deposition can be attained.
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| 45. |
- Ingason, A. S., et al.
(författare)
-
Growth and structural properties of Mg:C thin films prepared by magnetron sputtering
- 2010
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:15, s. 4225-4230
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the growth and structure properties of Mg:C thin films. The films are prepared using a dc magnetron sputtering discharge where the electrical resistance over the films is monitored during growth in-situ with a four point probe setup. The structural properties of the films are investigated using X-ray diffraction measurements and the elemental composition and binding in the films is determined using elastic recoil detection analysis and X-ray photoelectron spectroscopy. The results show that during co-sputtering the carbon flux influences the initial stages of the film growth. The films are made of polycrystalline magnesium grains embedded in a carbon network, the size of which depends on the carbon content, but amorphous phases cannot be excluded. The XPS measurements show the presence of carbidic carbon whereas X-ray measurements find no Mg:C phases. The overall stability of the films is found to depend on the carbon content, where stable films capped with a 14 nm Pd layer cannot be obtained with carbon content above 18%.
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| 46. |
- Ivanov, Sergey, et al.
(författare)
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Temperature-dependent structural and magnetic properties of R2MMnO6 double perovskites (R=Dy, Gd; M=Ni, Co)
- 2018
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Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 29:21, s. 18581-18592
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Tidskriftsartikel (refereegranskat)abstract
- The structural and magnetic properties of the Dy2CoMnO6, Dy2NiMnO6 and Gd2CoMnO6 double perovskites are investigated using X-ray powder diffraction and squid magnetometry. The materials adopt an orthorhombic structure (space ground Pnma) with disordered Co(Ni)/Mn cations, and exhibit ferrimagnetic transitions near T(C)85, 95, and 115K respectively. T-C was found to monotonously depend on the orthorhombic distortion (a-c)/(a+c) of the compounds. The crystal structure of the compounds was investigated as a function of temperature (16-1100K range), evidencing changes in the BO6 octahedron near T-C. The magnetic entropy changes are estimated for comparison of the magnetocaloric properties to those from literature.
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| 47. |
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| 48. |
- Jansson, Ulf, 1960-, et al.
(författare)
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Carbon-containing multi-component thin films
- 2019
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 688
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Forskningsöversikt (refereegranskat)abstract
- High entropy alloys (HEAs) have been a hot research area for many years. They are solid solutions of at least five elements in approximately equimolar compositions. The HEAs are assumed to be stabilized by a high entropy of mixing favouring a solid solution phase instead of a mixture of intermetallic phases. The importance of entropy of mixing and the true nature of HEAs are debated but the concept has contributed to an interesting development of new alloys. They idea of stabilizing solid solutions with many elements have recently been expanded to nitrides, borides, oxides and carbides. Furthermore, a growing number of thin film studies of these compounds are now published. In this paper we summarise recent results from studies of carbon-containing multi-component thin films based on the HEA concept. We will summarise some general observations connected to "high-entropy" materials. We also describe some general trends in metal-carbon interactions for transition metals and discuss how they should influence the formation of multi-component carbides. A summary of results on bulk multi-component carbide materials is also presented. We review published studies of carbon-containing multi-component thin films mainly deposited with magnetron-sputtering. The crystal structure, microstructure and properties of these films are described. Finally, we highlight some interesting topics for future research.
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| 49. |
- Jansson, Ulf, et al.
(författare)
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Design of carbide-based nanocomposite thin films by selective alloying
- 2011
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 206:4, s. 583-590
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews a series of studies on alloying of sputtered TiC coatings with weak carbide-forming metals, Me, such as Al, Fe, Ni, Pt and Cu. Metastable solid solutions with Me on the Ti sites are easily obtained by magnetron sputtering at low temperatures (< 300 °C). First principles density functional theory (DFT) calculations of such carbides show that a driving force exists to remove carbon from the structure as an alternative and kinetically more favourable route compared to Me precipitation. This leads to a situation where additional control of the phase composition is given by annealing: both direct influence during film growth, as well as through subsequent annealing. Thus, alloying of the nanocomposite with weak carbide-forming metals can be used to tune many mechanical, electric and magnetic properties of a carbide-based nanocomposite film.
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| 50. |
- Jansson, Ulf, et al.
(författare)
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Sputter deposition of transition-metal carbide films - A critical review from a chemical perspective
- 2013
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 536, s. 1-24
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Forskningsöversikt (refereegranskat)abstract
- Thin films based on transition-metal carbides exhibitmany interesting physical and chemical properties making them attractive for a variety of applications. The most widely used method to produce metal carbide films with specific properties at reduced deposition temperatures is sputter deposition. A large number of papers in this field have been published during the last decades, showing that large variations in structure and properties can be obtained. This review will summarise the literature on sputter-deposited carbide films based on chemical aspects of the various elements in the films. By considering the chemical affinities (primarily towards carbon) and structural preferences of different elements, it is possible to understand trends in structure of binary transition-metal carbides and the ternary materials based on these carbides. These trends in chemical affinity and structure will also directly affect the growth process during sputter deposition. A fundamental chemical perspective of the transition-metal carbides and their alloying elements is essential to obtain control of the material structure (from the atomic level), and thereby its properties and performance. This review covers a wide range of materials: binary transition-metal carbides and their nanocomposites with amorphous carbon; the effect of alloying carbide-based materials with a third element (mainly elements from groups 3 through 14); as well as the amorphous binary and ternary materials from these elements deposited under specific conditions or at certain compositional ranges. Furthermore, the review will also emphasise important aspects regarding materials characterisation which may affect the interpretation of data such as beam-induced crystallisation and sputter-damage during surface analysis.
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