| 1. |
- Dong, C. L., et al.
(författare)
-
Electronic structure of nanostructured ZnO from x-ray absorption and emission spectroscopy and the local density approximation
- 2004
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:19
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 2. |
- Butorin, S. M., et al.
(författare)
-
Resonant inelastic soft X-ray scattering studies of U(VI) reduction on iron surfaces
- 2004
-
Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 807:Scientific Basis for Nuclear Waste Management XXVII, s. 113-118
-
Tidskriftsartikel (refereegranskat)abstract
- The authors report on the spectroscopic anal. of several samples relevant to the processes governing the behavior of oxidized U species in groundwater solns. under anoxic conditions. Both Fe samples with different times of exposure to the U(IV) soln. and Fe metal-soln. interfaces in the liq. cell ex-situ and in-situ, resp. Resonant inelastic soft x-ray scattering is sensitive to the chem. state of U. The measurements were performed at a no. of energies of the primary photon beam across the U 5d absorption edge. The results unambiguously indicate the redn. of U(VI) to U(IV) on the Fe surface. [on SciFinder(R)]
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Lee, W. N., et al.
(författare)
-
Metabolic sensitivity of pancreatic tumour cell apoptosis to glycogen phosphorylase inhibitor treatment
- 2004
-
Ingår i: Br J Cancer. - 0007-0920. ; 91:12, s. 2094-100
-
Tidskriftsartikel (refereegranskat)abstract
- Inhibitors of glycogen breakdown regulate glucose homeostasis by limiting glucose production in diabetes. Here we demonstrate that restrained glycogen breakdown also inhibits cancer cell proliferation and induces apoptosis through limiting glucose oxidation, as well as nucleic acid and de novo fatty acid synthesis. Increasing doses (50-100 microM) of the glycogen phosphorylase inhibitor CP-320626 inhibited [1,2-(13)C(2)]glucose stable isotope substrate re-distribution among glycolysis, pentose and de novo fatty acid synthesis in MIA pancreatic adenocarcinoma cells. Limited oxidative pentose-phosphate synthesis, glucose contribution to acetyl CoA and de novo fatty acid synthesis closely correlated with decreased cell proliferation. The stable isotope-based dynamic metabolic profile of MIA cells indicated a significant dose-dependent decrease in macromolecule synthesis, which was detected at lower drug doses and before the appearance of apoptosis markers. Normal fibroblasts (CRL-1501) did not show morphological or metabolic signs of apoptosis likely due to their slow rate of growth and metabolic activity. This indicates that limiting carbon re-cycling and rapid substrate mobilisation from glycogen may be an effective and selective target site for new drug development in rapidly dividing cancer cells. In conclusion, pancreatic cancer cell growth arrest and death are closely associated with a characteristic decrease in glycogen breakdown and glucose carbon re-distribution towards RNA/DNA and fatty acids during CP-320626 treatment.
|
|
| 6. |
|
|
| 7. |
- Zhu, L, et al.
(författare)
-
Incidence of stroke in relation to cognitive function and dementia in the Kungsholmen Project
- 2000
-
Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 0028-3878 .- 1526-632X. ; 54:11, s. 2103-2107
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate whether cognitive function is related to incidence of stroke.Methods: A population-based cohort of 1551 subjects with no clinical history or signs of stroke, age 75 years and over at baseline, were followed up for 3 years. Individuals with a first-ever stroke event that was recorded in the Stockholm inpatient register after the date of baseline interview were considered as incident stroke patients. Diagnosis of stroke followed the International Classification of Disease, 9th Revision (ICD-9). Diagnosis of dementia was made according to the Diagnostic and Statistical Manual of Mental Disorders, 3rd ed., revised (DSM-III-R). Cognitive functioning was assessed with the Mini-Mental State Examination.Results: During the 4102 person-years of follow-up, 110 events were recorded, giving an overall incidence of stroke of 26.8 per 1000 person-years. Subjects with mild dementia had a relative risk of 2.6 (95% CI, 1.2 to 5.7) of developing stroke after controlling for the potential confounders. The corresponding figure for subjects with cognitive impairment was 2.0 (95% CI, 1.0 to 3.8; p = 0.05). There was a tendency for subjects who developed stroke to be more likely to have vascular factors (systolic blood pressure >180 mm Hg, heart disease, or diabetes mellitus) than those who did not.Conclusions: Mild dementia and cognitive impairment are associated with an increased incidence of stroke among subjects age 75 years old and over. Because stroke increases risk of dementia and prior stroke increases risk of a subsequent stroke, mild dementia and cognitive impairment may be a manifestation of clinically unrecognized stroke.
|
|
| 8. |
- Augustsson, A, et al.
(författare)
-
The electronic structure and lithiation of electrodes based on vanadium-oxide nanotubes
- 2003
-
Ingår i: Journal of Applied Physics. ; 94:8, s. 5083-5087
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Guo, J. H., et al.
(författare)
-
Polarization-dependent soft-x-ray absorption of highly oriented ZnO microrod arrays
- 2002
-
Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 14:28, s. 6969-6974
-
Tidskriftsartikel (refereegranskat)abstract
- Polarization-dependent x-ray absorption measurements were performed on crystalline ZnO three-dimensional arrays consisting of highly oriented microrods as well as on particulate thin films consisting of monodisperse spherical nanoparticles. Strong anisotropic effects have been observed for the highly oriented ZnO rods, but not for the isotropic spherical nanoparticles. Full-potential calculations of the orbital-resolved x-ray absorption of a ZnO wurtzite periodic crystal, including Zn 3d among the valence states, show very good agreement with the experimental findings. Comprehensive fundamental knowledge of the electronic structure of ZnO is obtained by probing and demonstrating the orbital symmetry of oxygen and its contribution to the conduction band of this important II-VI semiconductor.
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
|
|
| 17. |
- Huang, Z. L., et al.
(författare)
-
Novel heterocycle-based organic molecules with two-photon induced blue fluorescent emission
- 2003
-
Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 13:4, s. 708-711
-
Tidskriftsartikel (refereegranskat)abstract
- Two-photon absorption and two-photon induced blue emission characteristics of a series of heterocycle-based organic molecules are investigated experimentally and by quantum-chemical computations. The molecules consist of a typical A-pi-A' structure, where heterocycle, styryl and formyl groups are employed as A, pi-conjugated and A' moieties, respectively. Experimental results indicate that significant enhancements in the blue emission efficiency and two-photon absorption cross-sections can be achieved by replacing S and O atoms with an N atom in the heterocycle acceptor moiety, which is also supported by the quantum-chemical computations. Additionally, larger two-photon absorption cross-sections can be obtained by choosing appropriate solvents, as indicated by the computations.
|
|
| 18. |
- Kurmaev, E. Z., et al.
(författare)
-
Spectroscopic observation of polaron-lattice band structure in the conducting polymer polyaniline
- 2001
-
Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 13:17, s. 3907-3912
-
Tidskriftsartikel (refereegranskat)abstract
- We present the results of soft x-ray emission measurements for undoped and protonated polyemeraldine. We show that the polaron-lattice band structure fully accounts for the observed x-ray transitions. A finite spectral intensity of C Kα and N Kα XES is observed at the Fermi level for protonated polyemeraldine, supporting the applicability of the polaronic-metal model for highly conducting polymers.
|
|
| 19. |
- Käämbre, T, et al.
(författare)
-
Study of oxygen-C compound formation by NEXAFS and RIXS
- 2001
-
Ingår i: The European Physical Journal D. ; 16:1-3, s. 357-360
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction of oxygen with C60 molecules was studied on a C60 film which had been exposed simultaneously to oxygen and UV-light for 190 hours, producing an approximately C60O1 stoichiometry in the bulk of the sample. C K-edge and O K-edge NEXAFS (using total fluorescence yield detection) and resonant X-ray inelastic scattering (RIXS) spectra from the sample film were measured and the C K-edge data were compared to the spectra from pristine C60 as reference. The C K-edge absorption and emission spectral profiles of the oxygen-doped sample are similar to those of the C60 reference, suggesting that cage breaking of C60 under these conditions, if any, is negligible. However, the redistribution of intensities in the spectra indicates changes in the occupancies of different molecular orbitals, possibly due to changes in electron density upon reaction. Similarities of the O K-edge soft X-ray emission (SXES) spectra to several small oxygen-containing molecules is being discussed in terms of bonding models.
|
|
| 20. |
|
|
| 21. |
- Li, K., et al.
(författare)
-
MBE-based SiGe/Si heterojunction multilayer structures
- 2001
-
Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 227-228, s. 744-748
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, SiGe/Si multilayer heterostructures prepared by molecular beam epitaxy (MBE) are described with the aim of manufacturing SiGe heterojunction bipolar transistors (HBTs). Based on the simulations made by Medici, device structures have been designed and grown. The quality of the MBE layered structures has been characterized by reflection high-energy electron diffraction, X-ray diffraction, secondary ion mass spectrometry and spreading resistance. Furthermore, SiGe-HBTs have been fabricated. Promising DC and RF results of processed HBT devices have been obtained. © 2001 Elsevier Science B.V.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Nyberg, M., et al.
(författare)
-
Bond formation in titanium fulleride compounds studied through x-ray emission spectroscopy
- 2001
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 63:11, s. art. no.-115117
-
Tidskriftsartikel (refereegranskat)abstract
- The geometric and electronic structures of titanium fulleride complexes have been studied at the gradient corrected density-functional theory level by using various C60Tix (x=1,2) clusters. The cluster with the Ti atom binding on the six-ring site (eta (6)) Of the fullerene is shown to be lower in energy than those with Ti atom adsorbed on either five-ring (eta (5)) Or bridge(eta (2)) sites. The bond formation for titanium fulleride has further been examined by calculated nonresonant, resonant, and off-resonant . x-ray emission spectra of the clusters, and a comparison to the experimental counterpart. The examination shows that only the theoretical spectra of clusters with a six-ring adsorption site are in close agreement with the experimental x-ray emission spectra of titanium fulleride films. Our results indicate that off-resonant x-ray emission spectra provide an excellent basis for the probing of the bonding between metals and organic molecules.
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
|
|
| 32. |
|
|
| 33. |
|
|
