| 1. |
- Lindehammer, Sabina, et al.
(författare)
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Temporal trends of HLA genotype frequencies of type 1 diabetes patients in Sweden from 1986 to 2005 suggest altered risk
- 2008
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Ingår i: Acta Diabetologica. - : Springer Science and Business Media LLC. - 0940-5429 .- 1432-5233. ; 45:4, s. 231-5
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare the frequency of human leukocyte antigen (HLA) genotypes in 1-18-year-old patients with type 1 diabetes newly diagnosed in 1986-1987 (n = 430), 1996-2000 (n = 342) and in 2003-2005 (n = 171). We tested the hypothesis that the HLA DQ genotype distribution changes over time. Swedish type 1 diabetes patients and controls were typed for HLA using polymerase chain reaction amplification and allele specific probes for DQ A1* and B1* alleles. The most common type 1 diabetes HLA DQA1*-B1*genotype 0501-0201/0301-0302 was 36% (153/430) in 1986-1987 and 37% (127/342) in 1996-2000, but decreased to 19% (33/171) in 2003-2005 (P \ 0.0001). The 0501-0201/0501-0201 genotype increased from 1% in 1986-1987 to 7% in 1996-2000 (P = 0.0047) and to 5% in 2003-2005 (P > 0.05). This study in 1-18-year-old Swedish type 1 diabetes patients supports the notion that there is a temporal change in HLA risk.
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| 2. |
- Fallberg, Anna, et al.
(författare)
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A NEXAFS and XPS study of oxygen doped Cu3N
- 2024
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Ingår i: Journal of Physics D. - : IOP Publishing Ltd. - 0022-3727 .- 1361-6463.
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of pure and oxygen doped Cu3N, deposited by Chemical Vapour Deposition, have been studied with the NEXAFS technique both in the FLY and TEY mode and compared with XPS results. Cu, CuO and Cu2O have been used as reference samples in the investigation for detection of surface oxidation and contaminants. The aim has been to investigate how and if the chemical environment changes around Cu, N and O upon incorporation of oxygen in the Cu3N lattice. The recorded NEXAFS spectra are discussed in terms of valence electrons, crystal structure and local bonding environment. It was found that basically two oxygen absorption sites are possible in the crystal structure, (½, ½, 0) and (¼, ¼, ¼), and that the oxygen distribution between the two sites is probably given by the oxygen concentration.
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| 3. |
- Ahlén, Niklas, 1970-
(författare)
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Carbothermal synthesis of transition metal carbide and carbonitride whiskers via a Vapour-Liquid-Solid (VLS) growth mechanism
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A route for the synthesis of TiC, TiCyN1-y, TaxTi1-xC and TaxTi1-xCyN1-y whiskers via a carbothermal Vapour-Liquid-Solid (VLS) growth mechanism, yielding 70-90 vol.% whiskers, has been established. The whiskers were uniform in diameter (0.3-0.6mm), and had a length of about 10-30mm. The starting materials consisted of TiO2 and/or Ta2O5, C, a catalyst metal (Ni or Fe) and NaCl. Carbon was added to reduce the oxides, and NaCl to provide chlorine in the formation of TiClx(g) and TaOxCly(g) species. The overall chemical reaction is a straightforward carbothermal reduction process. The optimum synthesis temperature was found to be 1250°C for TiCyN1-y, TaxTi1-xC and TaxTi1-xCyN1-y whisker, and 1400°C for TiC. The growth direction of the whiskers was found to be <100> for TaC and TaxTi1-xC and either <100> or <111> for TiC. Nitridation of TiC whiskers yielded TiCyN1-y whiskers with morphology and chemical composition different from those obtained by the carbothermal VLS growth mechanism. From oxidation studies it was found that TiC had the lowest oxidation resistance (onset temperature Ton=390°C) and that TaC had the highest (Ton=550°C). The oxidation onset temperature was found to increase with increasing x-value for both TaxTi1-xC and TaxTi1-xCyN1-y whiskers. Microscopy studies (SEM and TEM) showed that whiskers with a native diameter exceeding 0.3 mm split into two halves along their length when oxidised. It was found that the TiO2 particle size of oxidised TaxTi1-xC whiskers are markedly smaller than that obtained from oxidation of TiC whiskers, whereas the Ta2O5 particle size was the same as that observed for oxidised TaC whiskers.
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| 4. |
- Arvidsson, Igor, 1976-
(författare)
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Theoretical Investigations of Boron Related Materials Using DFT
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the history of Chemistry, materials chemists have developed their ideas mainly by doing experiments in laboratories. The underlying motivation for this laboratory work has generally been pure curiosity or the ambition to find a solution to a specific problem. Minor changes in the composition or structure of a material can cause major changes in its properties. The development of powerful computers has now opened up the possibility to calculate properties of new materials using quantum mechanical methods.The Chemistry of different boron-related materials has been evaluated in this thesis by Density Functional Theory (DFT). Cubic boron nitride (c-BN) is a most interesting material for the microelectronics and tool industry. During thin film deposition of c-BN, several problems arise which most often result in unwanted BN isomorphs. Chemical processes at the (110) and (111) surface of c-BN have been investigated in order to shed light upon some of these complex processes. Typically adsorption energies and surface reconstruction were found to differ significantly between the two surfaces. Other materials investigated are layered transition-metal diborides (MeB2). Incorporation of transition-metal atoms into elemental boron in its most fundamental structure, ά-boron, has also been investigated. The calculations on MeB2 focused on the stability of the planar compared to the puckered structure of MeB2. Stability was investigated by calculating Density of States (DOS) and bond populations. Deviations in the cell parameters from their ideal values were also considered. A separate project concerned reactivity of the TiB2(001) surface. Molecular and dissociated adsorption energies and adsorption geometries were calculated for H2, H2O and O2. It was concluded that the titanium surface was more reactive than the boron surface and that the adsorption energies were comparable to or stronger than other well known surface-active compounds like TiO2.
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| 5. |
- Bauer, A. D., et al.
(författare)
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Corrosion behaviour of monocrystalline titanium nitride
- 1997
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Ingår i: Surface and Coatings Technology. ; 91:3, s. 208-214
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Tidskriftsartikel (refereegranskat)abstract
- The corrosion behaviour of monocrystalline and highly textured TiN films deposited onto single crystalline MgO has been investigated. It was found that films with high defect concentrations and elements of polycrystallinity had a reduced corrosion resistance. These films had low corrosion potentials and high critical and passive current densities. For high quality films the [110]- and [111]-orientations generally displayed better corrosion properties than films with [100]-orientation. Corrosion had different effects on films of different orientations: On [100]-oriented films loose rectangularly shaped flakes were observed. [110]-oriented films cracked because of compressive stresses, which in many cases caused the films to peel off during corrosion. On [111]-oriented films, finally, triangular pits were detected after corrosion. Films with high corrosion potentials had low values of critical and passive current densities. Non-destructive electrochemical analysis in combination with defect analysis can thus be used to predict the behaviour of these films on anodic polarisation.
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| 10. |
- Carlsson, Jan-Olof, et al.
(författare)
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Retinal surgery quality indicators for uncomplicated primary rhegmatogenous retinal detachment without a national registry
- 2022
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Ingår i: Acta Ophthalmologica. - : Wiley-Blackwell Publishing Inc.. - 1755-375X .- 1755-3768. ; 100:8, s. e1589-e1594
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The objective of this study was to evaluate the possibility of analysing quality indicators for uncomplicated primary rhegmatogenous retinal detachment in a hospital department of ophthalmology without the support of a national registry or need to collect data from referring ophthalmological centres.METHODS: In 2014, we operated 231 consecutive eyes with uncomplicated retinal detachment. Our quality indicators were primary anatomical success, final anatomical success and postoperative endophthalmitis. We reviewed medical records in our university surgical department retrospectively and compared them with medical records from the regional hospitals that had referred most of the operated patients and done their own postoperative examination. Our hypothesis was that any retinal re-detachment and/or serious postoperative complication would be reported back.RESULTS: The medical records at the surgical department revealed primary anatomic success for 91.3% of eyes and final anatomical success of 99.6%. The data from the regional hospitals confirmed that our hypothesis was correct. All patients with adverse outcomes were referred back for reoperation. Patients who were not referred again had an attached retina and showed no signs of endophthalmitis.CONCLUSION: Our hypothesis that data in the surgical department's medical records would closely reflect those in referring hospitals was borne out. This supports, under current conditions, an effective strategy for analysing chosen quality indicators without relying on a national registry or reviewing records from regional hospitals.
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