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| 3. |
- Schmitt, T, et al.
(author)
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Resonant soft X-ray emission spectroscopy of doped and undoped vanadium oxides
- 2004
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In: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 362:1-2, s. 143-150
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Journal article (peer-reviewed)abstract
- Resonant soft X-ray emission (RSXE) spectra of NaV2O5, MoxV1-xO2 and V2O3 have been recorded for a series of excitation energies at resonances of the V L- and O K-absorption band. Resonant excitation allows us, firstly, to separate V 3d and O 2p projected density-of-states of the valence band and, secondly, to study charge-neutral low-energy excitations due to resonant inelastic X-ray scattering (RIXS). We found that both the V L- and the O K-emission spectra clearly show components originating from O 2p- and V 3d-states, reflecting the high degree of hybridization of the valence band in all compounds. At threshold excitation we observed that NaV2O5 spectra are dominated by RIXS whereas MoxV1-xO2 and V2O3 spectra show bandlike features, which may be due to differences in the correlation effects of the compounds. We compared the RSXE spectra with cluster model calculations, which gives a good account for NaV2O5 whereas the RSXE spectra of the other compounds show RIXS only at certain energies well above the threshold. In fact, we interpret the trend in the RSXE spectra of the MoxV1-xO2 compound system as a successive filling of the (rigid) V 3d band with increasing Mo content. (C) 2003 Elsevier B.V. All rights reserved.
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| 5. |
- Augustsson, A, et al.
(author)
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The electronic structure and lithiation of electrodes based on vanadium-oxide nanotubes
- 2003
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In: Journal of Applied Physics. ; 94:8, s. 5083-5087
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Journal article (peer-reviewed)abstract
- The synthesis of a novel ligand 2′-[1-(2-pyridinyl)-ethylidene]-oxamohydrazide (Hapsox), from a series of 2-acetylpyridine acylhydrazones, and its complex with Co(III), which is the first in this series of complexes are described. Both the ligand and the complex were characterized by elemental analysis, IR, 1H-NMR, and 13C-NMR spectra, and the structure of the complex [Co(apsox)2]ClO4 was determined by X-ray structural analysis. It was established that [Co(apsox)2]ClO4 has an octahedral geometry with two tridentate apsox ligands in monoanionic form. Structural characteristics, lengths of the bonds, and angles between the bonds were typical for Co(III) complexes of distorted octahedral geometry. Both direct and template synthesis afforded the same geometrical isomer of the complex with two apsox ligands meridionally bound to the central metal ion, even in the case when equimolar quantities of Co(ClO4)2 and Hapsox were applied.
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| 6. |
- Dong, C. L., et al.
(author)
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Electronic structure of nanostructured ZnO from x-ray absorption and emission spectroscopy and the local density approximation
- 2004
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:19
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Journal article (peer-reviewed)abstract
- O 1s absorption spectroscopy (XAS) and O Kalpha emission spectroscopy (XES) were performed to study the electronic structure of nanostructured ZnO. The band gap is determined by the combined absorption-emission spectrum. Resonantly excited XES spectra showing an energy dependence in the spectral shape reveal the selected excitations to the different Zn 3d, 4s, and 4p states in hybridization with O 2p states. The partial density of state obtained from local density approximation (LDA) and LDA+U calculations are compared with the experimental results. The LDA+U approach is suitable to correct LDA self-interaction error of the cation d states. The atomic eigenstates of 3d in zinc and 2p in oxygen are energetically close, which induces the strong interaction between Zn 3d and O 2p states. This anomalous valence band cation-d-anion-p hybridization is verified by taking into account the strong localization of the Zn 3d states.
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| 7. |
- Guo, J.-H., et al.
(author)
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Molecular structure of alcohol-water mixtures
- 2003
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 91:15
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Journal article (peer-reviewed)abstract
- We use x-ray emission spectroscopy to elucidate the molecular structure of liquid methanol, water, and methanol-water solutions. We find that molecules in the pure liquid methanol predominantly persist as hydrogen-bonded chains and rings with six and/or eight molecules of equal abundance. For water-methanol solutions we find evidence of incomplete mixing at the microscopic level. Our results provide a new explanation for a smaller entropy increase in the solution due to water molecules bridging methanol chains to form rings.
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| 8. |
- Guo, J. H., et al.
(author)
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The molecular structure of alcohol-water mixtures determined by soft-X-ray absorption and emission spectroscopy
- 2004
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In: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 137-40:SI, s. 425-428
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Journal article (peer-reviewed)abstract
- We have examined the influence of the intermolecular interaction on the local electronic structure by using X-ray absorption and emission spectra of liquid methanol, water, and their mixtures (in molar ratios of 9:1 and 7:3). We find a strong involvement of hydrogen bonding in the mixing of water and methanol molecules. The local electronic structure of water and methanol clusters, where water cluster is bridging within a 6-member open-ring structured methanol cluster, is separately determined. The experimental findings suggest an incomplete mixing of water-alcohol systems and a strong self- association between methanol chain and water cluster through hydrogen bonding. The enhancement of joint water-methanol open-ring structure owes the explanation to the loss of entropy of the aqueous solutions.
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| 9. |
- Guo, J. H., et al.
(author)
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X-ray emission spectroscopy of hydrogen bonding and electronic structure of liquid water
- 2002
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 89:13
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Journal article (peer-reviewed)abstract
- We use x-ray emission spectroscopy to examine the influence of the intermolecular interaction on the local electronic structure of liquid water. By comparing x-ray emission spectra of the water molecule and liquid water, we find a strong involvement of the a(1)-symmetry valence-orbital in the hydrogen bonding. The local electronic structure of water molecules, where one hydrogen bond is broken at the hydrogen site, is separately determined. Our results provide an illustration of the important potential of x-ray emission spectroscopy for elucidating basic features of liquids.
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| 10. |
- Kashtanov, Stepan, et al.
(author)
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Local structures of liquid water studied by x-ray emission spectroscopy
- 2004
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:2
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Journal article (peer-reviewed)abstract
- The O Kalpha x-ray emission spectra of water clusters with different sizes and conformations embedded in a continuum medium are simulated. The calculations have successfully explained the experimental spectra of water in both gas and liquid phases. It is shown that the x-ray emission spectra are very sensitive to the local hydrogen bonding structures. Strong electron sharing between different water molecules is observed and its possible connection to the covalency of hydrogen bonding is discussed. The experimentally observed strong excitation energy dependence of the spectra has been interpreted in terms of the polarization and angular dependence for the gas phase, and in terms of variations of local hydrogen bonding structures for the liquid phase.
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| 12. |
- Lindmark, F, et al.
(author)
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H6D polymorphism in macrophage-inhibitory cytokine-1 gene associated with prostate cancer
- 2004
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In: Journal of the National Cancer Institute. - Umea Univ, Dept Radiat Sci Oncol, S-90187 Umea, Sweden. Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden. Umea Univ Hosp, Dept Urol & Androl, S-90185 Umea, Sweden. Wake Forest Univ, Sch Med, Ctr Human Genomics, Winston Salem, NC 27109 USA. Johns Hopkins Med Inst, Dept Urol, Baltimore, MD 21205 USA. : OXFORD UNIV PRESS INC. - 0027-8874 .- 1460-2105. ; 96:16, s. 1248-1254
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Journal article (peer-reviewed)abstract
- Background: Accumulating epidemiologic and molecular evidence suggest that inflammation is an important component in the etiology of prostate cancer. Macrophage-inhibitory cytokine-1 (MIC-1), a member of the transforming growth factor beta superfamily, is thought to play an important role in inflammation by regulating macrophage activity. We examined whether sequence variants in the MIC-1 gene are associated with the risk of prostate cancer. Methods: The study population, a population-based case-control study in Sweden, consisted of 1383 prostate cancer case patients and 780 control subjects. From 94 of the control subjects, we constructed gene-specific haplotypes of MIC-1 and identified four haplotype-tagging single-nucleotide polymorphisms (SNPs): Exon1+25 (V9L), Exon1+142 (S48T), IVS1+1809, and Exon2+2423 (H6D). All study subjects were genotyped for the four SNPs, and conditional logistic regression analysis was used to estimate odds ratios (ORs) with 95% confidence intervals (CIs). Results: A statistically significant difference (P = .006) in genotype frequency was observed for the nonsynonymous change H6D) (histidine to aspartic acid at position 6) between prostate cancer patients and control subjects. Carriers of the GC genotype, which results in the H6D change, experienced a lower risk of sporadic prostate cancer (OR = 0.80, 95% CI = 0.66 to 0.97) and of familial prostate cancer (OR = 0.61, 95% CI = 0.42 to 0.89) than the CC genotype carriers. In the study population, the proportion of prostate cancer cases attributable to the CC genotype was 7.2% for sporadic cancer and 19.2% for familial cancer. None of the other SNPs or haplotypes was associated with prostate cancer. Conclusion: This study shows an association between a nonsynonymous change (H6D) in the MIC-1 gene and prostate cancer. This finding supports the hypothesis that genetic variation in the inflammatory process contributes to prostate cancer susceptibility.
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| 13. |
- Lindstrom, B., et al.
(author)
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Combined multimode and singlemode fiber
- 2002
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In: Optical Fiber Communication Conference and Exhibit. ; , s. 628-629
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Conference paper (peer-reviewed)abstract
- A future proof combined MM- and SM-fiber is presented, which combines the advantages of both fiber types and makes upgrading and downgrading cheap and simple.
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| 14. |
- Mucci, L A, et al.
(author)
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Dietary acrylamide and cancer of the large bowel, kidney, and bladder : Absence of an association in a population-based study in Sweden
- 2003
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In: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 88:1, s. 84-89
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Journal article (peer-reviewed)abstract
- Recently, disturbingly high levels of acrylamide were unexpectedly detected in widely consumed food items, notably French fries, potato crisps, and bread. Much international public concern arose since acrylamide has been classified as a probable carcinogen, although based chiefly on laboratory evidence; informative human data are largely lacking. We reanalysed a population-based Swedish case-control study encompassing cases with cancer of the large bowel (N = 591), bladder (N = 263) and kidney (N = 133), and 538 healthy controls, assessing dietary acrylamide by linking extensive food frequency data with acrylamide levels in certain food items recorded by the Swedish National Food Administration. Unconditional logistic regression was used to estimate odds ratios, adjusting for potential confounders. We found consistently a lack of an excess risk, or any convincing trend, of cancer of the bowel, bladder, or kidney in high consumers of 14 different food items with a high (range 300-1200 mug kg(-1)) or moderate (range 30-299 mug kg(-1)) acrylamide content. Likewise, when we analysed quartiles of known dietary acrylamide intake, no association was found with cancer of the bladder or kidney. Unexpectedly, an inverse trend was found for large bowel cancer (P for trend 0.01) with a 40% reduced risk in the highest compared to lowest quartile. We found reassuring evidence that dietary exposure to acrylamide in amounts typically ingested by Swedish adults in certain foods has no measurable impact on risk of three major types of cancer. It should be noted, however, that relation of risk to the acrylamide content of all foods could not be studied.
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| 17. |
- Schmitt, Thorsten, et al.
(author)
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Electronic structure studies of V6O13 by soft X-ray emission spectroscopy : band-like and excitonic vanadium states
- 2004
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:12, s. 125103-
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Journal article (peer-reviewed)abstract
- Resonant soft x-ray emission (SXE) spectra of the mixed valence vanadium oxide V6O13 have been recorded for a series of excitation energies across the V L-absorption band. Resonant excitation allows one to distinguish between charge neutral low-energy excitations and continuum-excited, more band-like V 3d valence band states in the spectra. We find that the V L-emission spectra of V6O13 consist of two distinct components that can be assigned to nearly pure V 3d states, and to V 3dstates that are strongly hybridized with O 2p states, respectively. Band structure calculations of the density functional theory support the assignment of these features. At threshold excitation the V L-emission spectra of V6O13 show strong signatures from excitonic states, the energy dependence of which shows Raman-like behavior. We compare these spectral features in the resonant SXE spectra with cluster model calculations and assign them to dd excitations and charge-transfer excitations, respectively. Finally, we discuss changes in the V L-absorption and emission spectra that take place when changing the sample temperature from 295 K to 120 K. We relate the changes to redistributions in the V 3d partial density of states, which occur at the transition temperature for the metal-semiconductor-transition TMST=150K and find support in our temperature dependent band structure calculations.
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| 21. |
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| 22. |
- Ye, W, et al.
(author)
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No excess risk of colorectal cancer among alcoholics followed for up to 25 years
- 2003
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In: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 88:7, s. 1044-1046
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Journal article (peer-reviewed)abstract
- We conducted a population-based retrospective cohort study among 179 398 Swedish patients hospitalised for alcoholism from 1970 to 1994, and found no excess risk for colorectal cancers, overall or at any anatomical subsite. Our findings challenge the hypothesis that alcohol intake is a risk factor for cancer of the large bowel.
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