| 1. |
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| 2. |
- Santoro, V., et al.
(författare)
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HighNESS conceptual design report: Volume I
- 2024
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Ingår i: Journal of Neutron Research. - 1023-8166 .- 1477-2655. ; 25:3-4, s. 85-314
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Tidskriftsartikel (refereegranskat)abstract
- The European Spallation Source, currently under construction in Lund, Sweden, is a multidisciplinary international laboratory. Once completed to full specifications, it will operate the world’s most powerful pulsed neutron source. Supported by a 3 million Euro Research and Innovation Action within the EU Horizon 2020 program, a design study (HighNESS) has been completed to develop a second neutron source located below the spallation target. Compared to the first source, designed for high cold and thermal brightness, the new source has been optimized to deliver higher intensity, and a shift to longer wavelengths in the spectral regions of cold (CN, 2–20 Å), very cold (VCN, 10–120 Å), and ultracold (UCN, >500 Å) neutrons. The second source comprises a large liquid deuterium moderator designed to produce CN and support secondary VCN and UCN sources. Various options have been explored in the proposed designs, aiming for world-leading performance in neutronics. These designs will enable the development of several new instrument concepts and facilitate the implementation of a high-sensitivity neutron-antineutron oscillation experiment (NNBAR). This document serves as the Conceptual Design Report for the HighNESS project, representing its final deliverable.
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| 3. |
- Santoro, V., et al.
(författare)
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HighNESS conceptual design report: Volume II. the NNBAR experiment.
- 2024
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Ingår i: Journal of Neutron Research. - 1023-8166 .- 1477-2655. ; 25:3-4, s. 315-406
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Tidskriftsartikel (refereegranskat)abstract
- A key aim of the HighNESS project for the European Spallation Source is to enable cutting-edge particle physics experiments. This volume presents a conceptual design report for the NNBAR experiment. NNBAR would exploit a new cold lower moderator to make the first search in over thirty years for free neutrons converting to anti-neutrons. The observation of such a baryon-number-violating signature would be of fundamental significance and tackle open questions in modern physics, including the origin of the matter-antimatter asymmetry. This report shows the design of the beamline, supermirror focusing system, magnetic and radiation shielding, and anti-neutron detector necessary for the experiment. A range of simulation programs are employed to quantify the performance of the experiment and show how background can be suppressed. For a search with full background suppression, a sensitivity improvement of three orders of magnitude is expected, as compared with the previous search. Civil engineering studies for the NNBAR beamline are also shown, as is a costing model for the experiment.
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| 4. |
- Wang, Y.-D., et al.
(författare)
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Grain-to-grain stress interactions in an electrodeposited iron coating
- 2005
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 17:10, s. 1221-1226
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of residual stresses, in an iron electrolytic coating with the thickness of 1 mm, was discussed. It was found that the coating minimizes the influence of crystallographic texture and stress gradients. Scanning electron microscopy observations indicate that some cracks are produced in the direct current deposited layer. The results show that the grain size in the electrolytic coating observed by transmission electron microscopy is around 20 nm with an aspect ratio of 5:1
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| 5. |
- Gorishnyy, T.Z., et al.
(författare)
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Optimization of wear-resistant coating architectures using finite element analysis
- 2003
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 21:1, s. 332-339
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Tidskriftsartikel (refereegranskat)abstract
- The design of successful wear-resistant coating architectures requires simultaneous consideration of several factors. In particular, coatings which consist of CrN layers of varying thickness separated by thin Cr layers have the highest wear resistance for both aluminum and steel substrate materials, but a methodology was needed to optimize both the overall coating design and the individual layer thicknesses. This paper provides an initial step toward the development of future application specific coating designs and improved coating design methodologies.
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| 6. |
- Brennan, S L, et al.
(författare)
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FRAX provides robust fracture prediction regardless of socioeconomic status.
- 2013
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 25:1, s. 61-69
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the fracture risk assessment tool (FRAX) Canada calibration and discrimination according to income quintile in 51,327 Canadian women, with and without a competing mortality framework. Our data show that, under a competing mortality framework, FRAX provides robust fracture prediction and calibration regardless of socioeconomic status (SES).
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| 7. |
- Kanis, J A, et al.
(författare)
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The use of clinical risk factors enhances the performance of BMD in the prediction of hip and osteoporotic fractures in men and women.
- 2007
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Ingår i: Osteoporosis international. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 18:8, s. 1033-46
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Tidskriftsartikel (refereegranskat)abstract
- SUMMARY: BMD and clinical risk factors predict hip and other osteoporotic fractures. The combination of clinical risk factors and BMD provide higher specificity and sensitivity than either alone. INTRODUCTION AND HYPOTHESES: To develop a risk assessment tool based on clinical risk factors (CRFs) with and without BMD. METHODS: Nine population-based studies were studied in which BMD and CRFs were documented at baseline. Poisson regression models were developed for hip fracture and other osteoporotic fractures, with and without hip BMD. Fracture risk was expressed as gradient of risk (GR, risk ratio/SD change in risk score). RESULTS: CRFs alone predicted hip fracture with a GR of 2.1/SD at the age of 50 years and decreased with age. The use of BMD alone provided a higher GR (3.7/SD), and was improved further with the combined use of CRFs and BMD (4.2/SD). For other osteoporotic fractures, the GRs were lower than for hip fracture. The GR with CRFs alone was 1.4/SD at the age of 50 years, similar to that provided by BMD (GR = 1.4/SD) and was not markedly increased by the combination (GR = 1.4/SD). The performance characteristics of clinical risk factors with and without BMD were validated in eleven independent population-based cohorts. CONCLUSIONS: The models developed provide the basis for the integrated use of validated clinical risk factors in men and women to aid in fracture risk prediction.
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| 8. |
- Leslie, W D, et al.
(författare)
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Direct comparison of eight national FRAX® tools for fracture prediction and treatment qualification in Canadian women.
- 2013
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Ingår i: Archives of Osteoporosis. - : Springer Science and Business Media LLC. - 1862-3514 .- 1862-3522. ; 8:1-2, s. 145-
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Tidskriftsartikel (refereegranskat)abstract
- We compared the calibration of FRAX tools from Canada, the US (white), UK, Sweden, France, Australia, New Zealand, and China when used to assess fracture risk in 36,730 Canadian women. Our data underscores the importance of applying country-specific FRAX tools that are based upon high-quality national fracture epidemiology.
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| 9. |
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| 10. |
- Ayesa, S., et al.
(författare)
-
CYSTEINE PROTEASE INHIBITORS
- 2011
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Patent (populärvet., debatt m.m.)abstract
- Compounds of the formula IwhereinR1a is H; and R1b is C1-C6 alkyl, Carbocyclyl or Het; orR1a and R1b together define a saturated cyclic amine with 3-6 ring atoms;R2a and R2b are H, halo, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy; orR2a and R2b together with the carbon atom to which they are attached form a C3-C6cycloalkyl;R3 is a branched C5-C10alkyl chain, C2-C4haloalkyl or C3-C7cycloalkylmethyl,R4 is Het, Carbocyclyl,optionally substituted as defined in the specification and pharmaceutically acceptable salts,hydrates and N-oxides thereof; are inhibitors of cathepsin S and have utility in the treatment of psoriasis, autoimmune disorders and other disorders such as asthma, arteriosclerosis, COPD and chronic pain.
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| 11. |
- Calamba, Katherine, et al.
(författare)
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Effect of nitrogen vacancies on the growth, dislocation structure, and decomposition of single crystal epitaxial (Ti1-xAlx)N-y thin films
- 2021
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Ingår i: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 203
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Tidskriftsartikel (refereegranskat)abstract
- The effect of varying nitrogen vacancies on the growth, microstructure, spinodal decomposition and hardness values of predominantly single crystal cubic phase c-(Ti1-xAlx)N-y films was investigated. Epitaxial c-(Ti1-xAlx)N-y films with y = 0.67, 0.79, and 0.92 were grown on MgO(001) and MgO(111) substrates by magnetron sputter deposition. High N vacancy c-(Ti1-xAlx)N-0.67 films deposited on MgO(111) contained coherently oriented w-(0001) structures while segregated conical structures were observed on the films grown on MgO(001). High resolution STEM images revealed that the N-deficient growth conditions induced segregation with small compositional fluctuations that increase with the number of N vacancies. Similarly, strain map analysis of the epitaxial c-(Ti1-xAlx)N-y (001) and (111) films show fluctuations in strain concentration that scales with the number of N vacancies and increases during annealing. The spinodal decomposition coarsening rate of the epitaxial c-(Ti1-xAlx)N-y films was observed to increase with decreasing N vacancies. Nanoindentation showed decreasing trends in hardness of the as-deposited films as the N vacancies increase. Isothermal post-anneal at 1100 degrees C in vacuum for 120 min revealed a continuation in the increase in hardness for the film with the largest number of N vacancies (y = 0.67) while the hardness decreased for the films with y = 0.79 and 0.92. These results suggest that nitrogen-deficient depositions of c-(Ti1-xAlx)N-y films help to promote a self-organized phase segregation, while higher N vacancies generally increase the coherency strain which delays the coarsening process and can influence the hardness at high temperatures.
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| 12. |
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| 13. |
- Engberg, David L. J., et al.
(författare)
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Solid Solution and Segregation Effects in Arc-Deposited Ti1-xSixN Thin Films Resolved on the nanometer scale by 15N Isotopic Substitution in AtomP robe Tomography
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Nanostructured TiSiN is an important material in wear--‐resistant coatings for extending the lifetime of cutting tools. Yet, the understanding regarding the structure, phase composition, and bonding on the detailed nanometer scale, which determines the properties of TiSiN, is lacking. This limits our understanding of the growth phenomena and eventually a larger exploitation of the material. By substituting natN2 with 15N2 during reactive arc deposition of TiSiN thin films, atom probe tomography (APT) gives elemental sensitivity and sub-nanometer resolution, a finer scale than what can be obtained by commonly employed energy dispersive electron spectroscopy in scanning transmission electron microscopy. Using a combination of analytical transmission electron microscopy and APT we show that arc-deposited Ti0.92Si0.0815N and Ti0.81Si0.1915N exhibit Si segregation on the nanometer scale in the alloy films. APT composition maps and proximity histograms from domains with higher than average Ti content show that the TiN domains contain at least ~2 at. % Si for Ti0.92Si0.08N and ~5 at. % Si for Ti0.81Si0.19N, thus confirming the formation of solid solutions. The formation of relatively pure SiNy domains in the Ti0.81Si0.19N films is tied to pockets between microstructured, columnar features in the film. Finer SiNy enrichments seen in APT possibly correspond to tissue layers around TiN crystallites, thus effectively hindering growth of TiN crystallites, causing TiN renucleation and thus explaining the featherlike nanostructure within the columns of these films. For the stoichiometry of the TiN phase, we establish a global under stoichiometry, in accordance with the tendency for SiNy films to have tetrahedral bonding coordination towards a nominal Si3N4 composition.
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| 14. |
- Kanis, J A, et al.
(författare)
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A meta-analysis of previous fracture and subsequent fracture risk.
- 2004
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 35:2, s. 375-82
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Tidskriftsartikel (refereegranskat)abstract
- Previous fracture is a well-documented risk factor for future fracture. The aim of this study was to quantify this risk on an international basis and to explore the relationship of this risk with age, sex, and bone mineral density (BMD). We studied 15259 men and 44902 women from 11 cohorts comprising EVOS/EPOS, OFELY, CaMos, Rochester, Sheffield, Rotterdam, Kuopio, DOES, Hiroshima, and two cohorts from Gothenburg. Cohorts were followed for a total of 250000 person-years. The effect of a prior history of fracture on the risk of any fracture, any osteoporotic fracture, and hip fracture alone was examined using a Poisson model for each sex from each cohort. Covariates examined were age, sex, and BMD. The results of the different studies were merged by using the weighted beta-coefficients. A previous fracture history was associated with a significantly increased risk of any fracture compared with individuals without a prior fracture (RR = 1.86; 95% CI = 1.75-1.98). The risk ratio was similar for the outcome of osteoporotic fracture or for hip fracture. There was no significant difference in risk ratio between men and women. Risk ratio (RR) was marginally downward adjusted when account was taken of BMD. Low BMD explained a minority of the risk for any fracture (8%) and for hip fracture (22%). The risk ratio was stable with age except in the case of hip fracture outcome where the risk ratio decreased significantly with age. We conclude that previous history of fracture confers an increased risk of fracture of substantial importance beyond that explained by measurement of BMD. Its validation on an international basis permits the use of this risk factor in case finding strategies.
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| 15. |
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| 16. |
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| 17. |
- Kanis, J A, et al.
(författare)
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Smoking and fracture risk: a meta-analysis.
- 2005
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Ingår i: Osteoporosis international. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 16:2, s. 155-62
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Tidskriftsartikel (refereegranskat)abstract
- Smoking is widely considered a risk factor for future fracture. The aim of this study was to quantify this risk on an international basis and to explore the relationship of this risk with age, sex and bone mineral density (BMD). We studied 59,232 men and women (74% female) from ten prospective cohorts comprising EVOS/EPOS, DOES, CaMos, Rochester, Sheffield, Rotterdam, Kuopio, Hiroshima and two cohorts from Gothenburg. Cohorts were followed for a total of 250,000 person-years. The effect of current or past smoking, on the risk of any fracture, any osteoporotic fracture and hip fracture alone was examined using a Poisson model for each sex from each cohort. Covariates examined were age, sex and BMD. The results of the different studies were merged using the weighted beta-coefficients. Current smoking was associated with a significantly increased risk of any fracture compared to non-smokers (RR=1.25; 95% Confidence Interval (CI)=1.15-1.36). Risk ratio (RR) was adjusted marginally downward when account was taken of BMD, but it remained significantly increased (RR=1.13). For an osteoporotic fracture, the risk was marginally higher (RR=1.29; 95% CI=1.13-1.28). The highest risk was observed for hip fracture (RR=1.84; 95% CI=1.52-2.22), but this was also somewhat lower after adjustment for BMD (RR=1.60; 95% CI=1.27-2.02). Risk ratios were significantly higher in men than in women for all fractures and for osteoporotic fractures, but not for hip fracture. Low BMD accounted for only 23% of the smoking-related risk of hip fracture. Adjustment for body mass index had a small downward effect on risk for all fracture outcomes. For osteoporotic fracture, the risk ratio increased with age, but decreased with age for hip fracture. A smoking history was associated with a significantly increased risk of fracture compared with individuals with no smoking history, but the risk ratios were lower than for current smoking. We conclude that a history of smoking results in fracture risk that is substantially greater than that explained by measurement of BMD. Its validation on an international basis permits the use of this risk factor in case finding strategies.
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| 18. |
- Kanis, J A, et al.
(författare)
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The use of multiple sites for the diagnosis of osteoporosis.
- 2006
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Ingår i: Osteoporosis international. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 17:4, s. 527-34
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: It has been suggested that bone mineral density (BMD) measurements should be made at multiple sites, and that the lowest T-score should be taken for the purpose of diagnosing osteoporosis. PURPOSE: The aim of this study was to examine the use of BMD measurements at the femoral neck and lumbar spine alone and in combination for fracture prediction. METHODS: We studied 19,071 individuals (68% women) from six prospective population-based cohorts in whom BMD was measured at both sites and fracture outcomes documented over 73,499 patient years. BMD values were converted to Z-scores, and the gradient of risk for any osteoporotic fracture and for hip fracture was examined by using a Poisson model in each cohort and each gender separately. Results of the different studies were merged using weighted beta-coefficients. RESULTS: The gradients of risk for osteoporotic fracture and for hip fracture were similar in men and women. In men and women combined, the risk of any osteoporotic fracture increased by 1.51 [95% confidence interval (CI)=1.42-1.61] per standard deviation (SD) decrease in femoral-neck BMD. For measurements made at the lumbar spine, the gradient of risk was 1.47 (95% CI=1.38-1.56). Where the minimum of the two values was used, the gradient of risk was similar (1.55; 95% CI=1.45-1.64). Higher gradients of risk were observed for hip fracture outcomes: with BMD at the femoral neck, the gradient of risk was 2.45 (95% CI=2.10-2.87), with lumbar BMD was 1.57 (95% CI=1.36-1.82), and with the minimum value of either femoral neck and lumbar spine was 2.11 (95% CI=1.81-2.45). Thus, selecting the lowest value for BMD at either the femoral neck or lumbar spine did not increase the predictive ability of BMD tests. By contrast, the sensitivity increased so that more individuals were identified but at the expense of specificity. Thus, the same effect could be achieved by using a less stringent T-score for the diagnosis of osteoporosis. CONCLUSIONS: Since taking the minimum value of the two measurements does not improve predictive ability, its clinical utility for the diagnosis of osteoporosis is low.
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| 19. |
- Leslie, W D, et al.
(författare)
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Fracture risk assessment without bone density measurement in routine clinical practice
- 2012
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Ingår i: Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. - : Springer Science and Business Media LLC. - 1433-2965 .- 0937-941X. ; 23:1, s. 75-85
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Tidskriftsartikel (refereegranskat)abstract
- Fracture probability assessed without bone mineral density (BMD) could potentially be sufficient for clinical decision making in many individuals categorized as low or high fracture risk. For individuals falling in a moderate risk range, there is incremental value in using BMD in the probability calculation as this appropriately reclassifies risk in over one third of the individuals.
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| 20. |
- Norrby, Niklas, et al.
(författare)
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High pressure and high temperature stabilization of cubic AlN in Ti0.60Al0.40N
- 2013
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 113:5
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, the decomposition of unstable arc evaporated Ti0.6Al0.4N at elevated temperatures and quasihydrostatic pressures has been studied both experimentally and by first-principles calculations. High pressure and high temperature (HPHT) treatment of the samples was realized using the multi anvil press and diamond anvil cell techniques. The products of the HPHT treatment of Ti0.6Al0.4N were investigated using x-ray diffractometry and transmission electron microscopy. Complimentary calculations show that both hydrostatic pressure and high temperature stabilize the cubic phase of AlN, which is one of the decomposition products of Ti0.6Al0.4N. This is in agreement with the experimental results which in addition suggest that the presence of Ti in the system serves to increase the stability region of the cubic c-AlN phase. The results are industrially important as they show that Ti0.6Al0.4N coatings on cutting inserts do not deteriorate faster under pressure due to the cubic AlN to hexagonal AlN transformation.
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| 21. |
- Reeve, P. A. P., et al.
(författare)
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Radical Functionalization of Unsaturated Amino Acids : Synthesis of Side-Chain-Fluorinated, Azido-Substituted, and Hydroxylated Amino Acids
- 2019
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Ingår i: ACS Omega. - : American Chemical Society. - 2470-1343. ; 4:6, s. 10854-10865
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Tidskriftsartikel (refereegranskat)abstract
- A range of enantiomerically pure protected side-chain-fluorinated amino acids has been prepared (13 examples) by treatment of protected amino acids containing unsaturated side chains with a combination of Fe(III)/NaBH4 and Selectfluor. The modification of the conditions by replacement of Selectfluor with NaN3 allowed the preparation of side-chain azido-substituted amino acids (five examples), which upon catalytic hydrogenation gave the corresponding amines, isolated as lactams (four examples). Radical hydration of the unsaturated side chains leading to side-chain-hydroxylated protected amino acids has also been demonstrated.
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| 22. |
- Rogström, Lina, et al.
(författare)
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Decomposition routes and strain evolution in arc deposited TiZrAlN coatings
- 2019
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Ingår i: Journal of Alloys and Compounds. - : ELSEVIER SCIENCE SA. - 0925-8388 .- 1873-4669. ; 779, s. 261-269
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Tidskriftsartikel (refereegranskat)abstract
- Phase, microstructure, and strain evolution during annealing of arc deposited TiZrAlN coatings are studied using in situ x-ray scattering and ex situ transmission electron microscopy. We find that the decomposition route changes from nucleation and growth of wurtzite AlN to spinodal decomposition when the Zr-content is decreased and the Al-content increases. Decomposition of Ti0.31Zr0.24Al0.45N results in homogeneously distributed wurtzite AlN grains in a cubic, dislocation-dense matrix of TiZrN consisting of domains of different chemical composition. The combination of high dislocation density, variation of chemical composition within the cubic grains, and evenly distributed wurtzite AlN grains results in high compressive strains, -1.1%, which are retained after 3 h at 1100 degrees C. In coatings with higher Zr-content, the strains relax during annealing above 900 degrees C due to grain growth and defect annihilation. (C) 2018 Elsevier B.V. All rights reserved.
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| 23. |
- Salamania, Janella, 1992-, et al.
(författare)
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Elucidating dislocation core structures in titanium nitride through high-resolution imaging and atomistic simulations
- 2022
-
Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 224
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Tidskriftsartikel (refereegranskat)abstract
- Although titanium nitride (TiN) is among the most extensively studied and thoroughly characterizedthin-film ceramic materials, detailed knowledge of relevant dislocation core structures is lacking. Byhigh-resolution scanning transmission electron microscopy (STEM) of epitaxial single crystal (001)-oriented TiN films, we identify different dislocation types and their core structures. These include, besidesthe expected primary a/2{110}h110i dislocation, Shockley partial dislocations a/6{111}h112i and sessileLomer edge dislocations a/2{100}h011i. Density-functional theory and classical interatomic potentialsimulations complement STEM observations by recovering the atomic structure of the different disloca-tion types, estimating Peierls stresses, and providing insights on the chemical bonding nature at the core.The generated models of the dislocation cores suggest locally enhanced metal–metal bonding, weakenedTi-N bonds, and N vacancy-pinning that effectively reduces the mobilities of {110}h110i and {111}h112idislocations. Our findings underscore that the presence of different dislocation types and their effects onchemical bonding should be considered in the design and interpretations of nanoscale and macroscopicproperties of TiN.
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| 24. |
- Salamania, Janella, et al.
(författare)
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High temperature decomposition and age hardening of single-phase wurtzite Ti1−xAlxN thin films grown by cathodic arc deposition
- 2024
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Ingår i: Physical Review Materials. - : AMER PHYSICAL SOC. - 2475-9953. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Wurtzite TmAlN (T-m = transition metal) themselves are of interest as semiconductors with tunable band gap, insulating motifs to superconductors, and piezoelectric crystals. Characterization of wurtzite TmAlN is challenging because of the difficulty to synthesize them as single-phase solid solution and such thermodynamic, elastic properties, and high temperature behavior of wurtzite Ti1-xAlxN is unknown. Here, we investigated the high temperature decomposition behavior of wurtzite Ti1-xAlxN films using experimental methods combined with first-principles calculations. We have developed a method to grow single-phase metastable wurtzite Ti1-xAlxN (x = 0.65, 0.75, 085, and 0.95) solid-solution films by cathodic arc deposition using low duty-cycle pulsed substrate-bias voltage. We report the full elasticity tensor for wurtzite Ti1-xAlxN as a function of Al content and predict a phase diagram including a miscibility gap and spinodals for both cubic and wurtzite Ti1-xAlxN. Complementary high-resolution scanning transmission electron microscopy and chemical mapping demonstrate decomposition of the films after high temperature annealing (950 degrees C), which resulted in nanoscale chemical compositional modulations containing Ti-rich and Al-rich regions with coherent or semicoherent interfaces. This spinodal decomposition of the wurtzite film causes age hardening of 1-2 GPa.
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| 25. |
- Sangiovanni, Davide, et al.
(författare)
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Strength, transformation toughening, and fracture dynamics of rocksalt-structure Ti1-xAlxN (0 <= x <= 0.75) alloys
- 2020
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Ingår i: Physical Review Materials. - : AMER PHYSICAL SOC. - 2475-9953. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio-calculated ideal strength and toughness describe the upper limits for mechanical properties attainable in real systems and can, therefore, be used in selection criteria for materials design. We employ density-functional ab initio molecular dynamics (AIMD) to investigate the mechanical properties of defect-free rocksalt-structure (B1) TiN and B1 Ti1-xAlxN (x = 0.25, 0.5, 0.75) solid solutions subject to [001], [110], and [111] tensile deformation at room temperature. We determine the alloys ideal strength and toughness, elastic responses, and ability to plastically deform up to fracture as a function of the Al content. Overall, TiN exhibits greater ideal moduli of resilience and tensile strengths than (Ti,Al)N solid solutions. Nevertheless, AIMD modeling shows that, irrespective of the strain direction, the binary compound systematically fractures by brittle cleavage at its yield point. The simulations also indicate that Ti0.5Al0.5N and Ti0.25Al0.75N solid solutions are inherently more resistant to fracture and possess much greater toughness than TiN due to the activation of local structural transformations (primarily of B1 -amp;gt; wurtzite type) beyond the elastic-response regime. In sharp contrast, (Ti,Al)N alloys with 25% Al exhibit similar brittleness as TiN. The results of this work are examples of the limitations of elasticity-based criteria for prediction of strength, brittleness, ductility, and toughness in materials able to undergo phase transitions with loading. Comparing present and previous findings, we suggest a general principle for design of hard ceramic solid solutions that are thermodynamically inclined to dissipate extreme mechanical stresses via transformation toughening mechanisms.
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| 26. |
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| 27. |
- Talyzin, A V, et al.
(författare)
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Superhard and superelastic films of polymeric C60
- 2001
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Ingår i: Diamond and related materials. - 0925-9635 .- 1879-0062. ; 10:11, s. 2044-2048
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Tidskriftsartikel (refereegranskat)abstract
- The C60 thin film deposited on steel substrate was transformed by high pressure-high temperature treatment to a superhard and superclastic material. The films were studied by Raman spectroscopy in situ at 20 GPa after heating at 300░C and ex situ after the quenching. The hardness and elastic properties of the high-pressure phases have been characterized with nanoindentation. The hardness of the films were determined to be 0.5 ▒ 0.1 GPa and 61.9 ▒ 9 GPa for unmodified C60 and HPHT treated films, respectively. The hardness of the pressurized film is higher than for cubic BN but lower than hardness values reported for ultrahard fullerite samples prepared from powders. An interesting observation was that the HPHT treated film showed an extreme elastic response with an elastic recovery of approximately 90%. ⌐ 2001 Elsevier Science B.V. All rights reserved.
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