| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Williamson, Alice, et al.
(author)
-
Genome-wide association study and functional characterization identifies candidate genes for insulin-stimulated glucose uptake
- 2023
-
In: Nature Genetics. - : Springer Nature. - 1061-4036 .- 1546-1718. ; 55:6, s. 973-983
-
Journal article (peer-reviewed)abstract
- Distinct tissue-specific mechanisms mediate insulin action in fasting and postprandial states. Previous genetic studies have largely focused on insulin resistance in the fasting state, where hepatic insulin action dominates. Here we studied genetic variants influencing insulin levels measured 2 h after a glucose challenge in >55,000 participants from three ancestry groups. We identified ten new loci (P < 5 × 10-8) not previously associated with postchallenge insulin resistance, eight of which were shown to share their genetic architecture with type 2 diabetes in colocalization analyses. We investigated candidate genes at a subset of associated loci in cultured cells and identified nine candidate genes newly implicated in the expression or trafficking of GLUT4, the key glucose transporter in postprandial glucose uptake in muscle and fat. By focusing on postprandial insulin resistance, we highlighted the mechanisms of action at type 2 diabetes loci that are not adequately captured by studies of fasting glycemic traits.
|
|
| 5. |
- Wulaningsih, W., et al.
(author)
-
A competing risks analysis of the association between prediagnostic serum glucose and lipids and breast cancer survival
- 2016
-
In: Cancer Research. - Kings Coll London, Div Canc Studies, Canc Epidemiol Grp, London WC2R 2LS, England. Kings Coll London, Inst Math & Mol Biomed, London WC2R 2LS, England. Uppsala Univ, Uppsala, Sweden. Reg Canc Ctr, Uppsala, Sweden. Karolinska Inst, Inst Environm Med, S-10401 Stockholm, Sweden. Karolinska Inst, S-10401 Stockholm, Sweden. AstraZeneca R&D, Mlndal, Switzerland. CALAB Res, Madrid, Spain.. - 0008-5472 .- 1538-7445. ; 76
-
Journal article (other academic/artistic)
|
|
| 6. |
|
|
| 7. |
- GOTHELID, M, et al.
(author)
-
GEOMETRY OF THE GE(111)-AU(ROOT-3X-ROOT-3)R 30-DEGREES RECONSTRUCTION
- 1994
-
In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 50:7, s. 4470-4475
-
Journal article (peer-reviewed)abstract
- A structure model for the Ge(111)-Au(root 3X root 3)R30 degrees surface reconstruction is proposed based on scanning tunneling microscopy (STM) and photoelectron spectroscopy on the Ge 3d and Au 4f core lines. The basic unit is a Au3Ge molecule binding in one-third of the T-1 substrate sites with a gold trimer pointing out of the surface. This leaves two-thirds of a monolayer of unoccupied T-1 sites which make up a hexagonal honeycomb pattern. Two types of STM images have been obtained which are explained within this model, where either the trimers or the substrate Ge atoms are probed depending on the specific tip conditions in combination with the sample bias voltage. Furthermore, small insets of a metallic (1X1) structure are found at low gold coverage together with a distorted (2X2) surface structure.
|
|
| 8. |
- Göthelid, M., et al.
(author)
-
Adatom and rest-atom contributions in Ge(111)c(2×8) and Ge(111)-Sn(7×7) core-level spectra
- 1993
-
In: Physical Review B. - 0163-1829. ; 48:3, s. 2012-2015
-
Journal article (peer-reviewed)abstract
- We have identified the adatom contribution in the Ge 3d core-level spectra from the clean Ge(111)c(2×8) surface, shifted 0.17 eV to higher binding energy compared to the bulk. This adatom component vanishes in the Ge(111)-Sn(7×7) surface core-level spectra where Sn occupies the adatom site. Moreover we report the observation of an earlier proposed difference between the rest atoms in the c(2×8) structure, and also a shift to lower binding energy for the rest atoms in both structures studied. © 1993 The American Physical Society.
|
|
| 9. |
- Hammar, M., et al.
(author)
-
In situ ultrahigh vacuum transmission electron microscopy studies of hetero-epitaxial growth I. Si(001)/Ge
- 1996
-
In: Surface Science. - : Elsevier BV. - 0039-6028. ; 349:2, s. 129-144
-
Journal article (peer-reviewed)abstract
- We use ultrahigh vacuum transmission electron microscopy (UHV-TEM) to study the growth of Ge on Si(001) in real time at different temperatures and for coverages ranging from the initial monolayers to the development and relaxation of 3D islands. During growth of the first monolayers the surface gradually changes from a disordered missing-dimer structure to a rather well ordered (2 × 8) reconstruction, an evolution clearly resolved by the TEM. As the coverage is increased 3D islands starts to form. The growth and relaxation of these islands are shown to depend significantly on the temperature, e.g. with different dislocations formed at high and low temperatures. We interpret this difference in terms of the brittle-ductile transition in Ge, below which dislocation glide is frozen out. An interesting observation is that islands grown at low temperatures are more fully relaxed than those grown at higher temperatures. At high enough temperature the islands are initially, up to a specific size, coherent with the substrate and further growth occurs in a remarkably oscillatory fashion with the introduction of each (60°-type) dislocation, where the core of the island, of about 2000 Å in diameter, remains fully strained. However, in the low-temperature regime the islands grow relaxed from the outset with pure edge dislocations continuously being introduced in the moving edges. For temperatures less than 600̊C the transition from 2D to 3D growth occurs via the formation of small and strained 3D islands, so-called "hut clusters". We monitor the nucleation and characteristics of these clusters and discuss their possible role in the formation of relaxed 3D islands. The different growth mechanisms are discussed in terms of a simple model for the energetics of strain-relaxed islands, leading to a qualitative description of the temperature-dependent growth modes.
|
|
| 10. |
- Le Lay, G., et al.
(author)
-
STM and synchrotron radiation studies of "prototypical" metal{plus 45 degree rule}semiconductor systems
- 1994
-
In: Surface Science. - 0039-6028. ; 307-309:PART A, s. 280-294
-
Journal article (peer-reviewed)abstract
- Since the origin of surface science noble metal{plus 45 degree rule}elemental semiconductor couples have been considered as "prototypical" systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development of the near-field microscopies and the extensive use of synchrotron radiation in surface crystallography and in high-resolution photoelectron spectroscopy. In the last few years, lead, as a replacement inert metal, has nearly gained the pole position in the display of exotic behaviour. This paper gives a flavour of this mystery story and highlights some puzzling questions. © 1994.
|
|
| 11. |
- LeGoues, F. K., et al.
(author)
-
Cyclic growth of strain-relaxed islands
- 1994
-
In: Physical Review Letters. - 0031-9007. ; 73:2, s. 300-303
-
Journal article (peer-reviewed)abstract
- Growth of Ge islands on Si(001) is observed in real time with high spatial resolution, using UHV transmission electron microscopy. We are able to monitor the formation of successive strain-relieving dislocations. The shape of the island oscillates as it grows, with each cycle corresponding to the introduction of one dislocation. Such growth cycles are shown to be a general feature of the growth of strain-relaxed islands, occurring even in equilibrium. © 1994 The American Physical Society.
|
|
| 12. |
- LeGoues, F. K., et al.
(author)
-
In situ TEM study of the growth of Ge on Si(111)
- 1996
-
In: Surface Science. - : Elsevier BV. - 0039-6028. ; 349:3, s. 249-266
-
Journal article (peer-reviewed)abstract
- We have used the UHV-TEM to study the growth of Ge on Si(111) in situ, from the deposition of the first monolayer to complete relaxation by the introduction of dislocations. We show that, at 650°C, the growth of Ge islands is dominated by steps on the surface. Indeed, islands nucleated on steps that run along the 〈112〉 direction have a very high aspect ratio, while other islands are roughly triangular in shape. Dislocations form initially exclusively by coalescence of these smaller islands. Further growth involves a complicated competition between surrounding strained islands and the relaxed island. At lower temperature (350°C), steps still are a preferred site for island formation, but the limited surface diffusion makes it possible for islands to also nucleate on flat terraces. In this case, an island grows by incorporating dislocations at its edge, which results in a completely relaxed island from the start, and a very uniform network of dislocations. These in situ electron microscopy studies reveal a much more complicated and rich growth process than previously imagined, and tie previously obtained results together into a single picture.
|
|
| 13. |
- LELAY, G, et al.
(author)
-
STM AND SYNCHROTRON-RADIATION STUDIES OF PROTOTYPICAL METAL-SEMICONDUCTOR SYSTEMS
- 1994
-
In: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 307, s. 280-294
-
Journal article (peer-reviewed)abstract
- Since the origin of surface science noble metal/elemental semiconductor couples have been considered as ''prototypical'' systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development of the near-field microscopies and the ''tensive use of synchrotron radiation in surface crystallography and in high-resolution photoelectron spectroscopy. In the last few years, lead, as a replacement inert metal, has nearly gained the pole position in the display of exotic behaviour. This paper gives a flavour of this mystery story and highlights some puzzling questions.
|
|
| 14. |
|
|
| 15. |
- Pereira, Maria J, 1981-, et al.
(author)
-
FKBP5 expression in human adipose tissue increases following dexamethasone exposure and is associated with insulin resistance
- 2014
-
In: Metabolism: Clinical and Experimental. - : Elsevier BV. - 0026-0495 .- 1532-8600. ; 63:9, s. 1198-1208
-
Journal article (peer-reviewed)abstract
- Objective To study effects of dexamethasone on gene expression in human adipose tissue aiming to identify potential novel mechanisms for glucocorticoid-induced insulin resistance. Materials/methods Subcutaneous and omental adipose tissue, obtained from non-diabetic donors (10 M/15 F; age: 28-60 years; BMI: 20.7-30.6 kg/m2), was incubated with or without dexamethasone (0.003-3 μmol/L) for 24 h. Gene expression was assessed by microarray and real time-PCR and protein expression by immunoblotting. Results FKBP5 (FK506-binding protein 5) and CNR1 (cannabinoid receptor 1) were the most responsive genes to dexamethasone in both subcutaneous and omental adipose tissue (~ 7-fold). Dexamethasone increased FKBP5 gene and protein expression in a dose-dependent manner in both depots. The gene product, FKBP51 protein, was 10-fold higher in the omental than in the subcutaneous depot, whereas the mRNA levels were similar. Higher FKBP5 gene expression in omental adipose tissue was associated with reduced insulin effects on glucose uptake in both depots. Furthermore, FKBP5 gene expression in subcutaneous adipose tissue was positively correlated with serum insulin, HOMA-IR and subcutaneous adipocyte diameter and negatively with plasma HDL-cholesterol. FKBP5 SNPs were found to be associated with type 2 diabetes and diabetes-related phenotypes in large population-based samples. Conclusions Dexamethasone exposure promotes expression of FKBP5 in adipose tissue, a gene that may be implicated in glucocorticoid-induced insulin resistance. © 2014 Elsevier Inc.
|
|
| 16. |
|
|
| 17. |
- Rowley, M., et al.
(author)
-
A latent class model for competing risks
- 2017
-
In: Statistics in Medicine. - : Wiley. - 0277-6715 .- 1097-0258. ; 36:13, s. 2100-2119
-
Journal article (peer-reviewed)abstract
- Survival data analysis becomes complex when the proportional hazards assumption is violated at population level or when crude hazard rates are no longer estimators of marginal ones. We develop a Bayesian survival analysis method to deal with these situations, on the basis of assuming that the complexities are induced by latent cohort or disease heterogeneity that is not captured by covariates and that proportional hazards hold at the level of individuals. This leads to a description from which risk-specific marginal hazard rates and survival functions are fully accessible, 'decontaminated' of the effects of informative censoring, and which includes Cox, random effects and latent classmodels as special cases. Simulated data confirm that our approach can map a cohort's substructure and remove heterogeneity-induced informative censoring effects. Application to data from the Uppsala Longitudinal Study of Adult Men cohort leads to plausible alternative explanations for previous counter-intuitive inferences on prostate cancer. The importance of managing cardiovascular disease as a comorbidity in women diagnosed with breast cancer is suggested on application to data from the Swedish Apolipoprotein Mortality Risk Study.
|
|
| 18. |
|
|
| 19. |
- TORNEVIK, C, et al.
(author)
-
ADSORPTION OF SN ON SI(111)7X7 - RECONSTRUCTIONS IN THE MONOLAYER REGIME
- 1994
-
In: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 314:2, s. 179-187
-
Journal article (peer-reviewed)abstract
- Different monolayer phases of Sn on Si(111)7 x 7 have been studied by means of scanning tunneling microscopy (STM), core-level photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS). The STM results show that square-root 3 x square-root 3 reconstructions are obtained for room-temperature deposition of 1/3 ML of Sn followed by sample annealing in a broad temperature range. A T4 Sn adatom square-root 3 x square-root 3 phase is formed for temperatures between 500 and 800-degrees-C, with a concentration of defects that is strongly dependent on the temperature and which is as high as 25% for the lowest temperatures. Above 825-degrees-C a second square-root 3 x square-root 3 adatom reconstruction is formed, a mosaic-like phase with a 1: 1 mixture of Si and Sn atoms in T4 positions. The results from investigations of the higher coverage 2 square-root 3 x 2 square-root 3 reconstruction by XPS and RBS support the theory that this phase is a two-layer epitaxial Sn structure with all Si(111) dangling bonds saturated. The Sn coverage for this phase was determined to be between 1 and 1.2 ML.
|
|
| 20. |
- Törnevik, C., et al.
(author)
-
Adsorption of Sn onSi(111)7 × 7 : reconstructions in the monolayer regime
- 1994
-
In: Surface Science. - 0039-6028. ; 314:2, s. 179-187
-
Journal article (peer-reviewed)abstract
- Different monolayer phases of Sn on Si(111)7 × 7 have been studied by means of scanning tunneling microscopy (STM), core-level photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS). The STM results show that 3 × 3 reconstructions are obtained for room-temperature deposition of 1 3 ML of Sn followed by sample annealing in a broad temperature range. A T4 Sn adatom 3 ×3 phase is formed for temperatures between 500 and 800°C, with a concentration of defects that is strongly dependent on the temperature and which is as high as 25% for the lowest temperatures. Above 825°C a second 3×3 adatom reconstruction is formed, a mosaic-like phase with a 1:1 mixture of Si and Sn atoms in T4 positions. The results from investigations of the higher coverage 2 3 × 2 3 reconstruction by XPS and RBS support the theory that this phase is a two-layer epitaxial Sn structure with all Si(111) dangling bonds saturated. The Sn coverage for this phase was determined to be between 1 and 1.2 ML. © 1994.
|
|
| 21. |
- Vaitkus, J., et al.
(author)
-
Scanning tunneling microscopy of CdSe single crystal cleaved and "real" surface
- 1994
-
In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 138:1-4, s. 545-549
-
Journal article (peer-reviewed)abstract
- Ultrahigh vacuum-cleaved and as-grown surfaces of CdSe single crystals were investigated by scanning tunneling microscopy. The single crystals were grown by Reynolds-Green method. Striations and terrace-step structure have been found. The surface atomic geometry was found and investigated. The (1120) face geometry (structure formed by elementary cell of 0.75 × 0.7 nm2) as well as other type structures (e.g., 2.1 × 0.75 nm2 elementary cell) have been determined. The variations of the band gap at the surface have been found. The band values in the range 2.0-2.6 eV on a cleaved surface and 1.1-2.0 eV on an as-grown surface were measured and explained as being the influence of surface relaxation and gas adsorption. © 1994.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
- Arthur, R., et al.
(author)
-
Serum inflammatory markers in relation to prostate cancer severity and death in the Swedish AMORIS study
- 2018
-
In: International Journal of Cancer. - : WILEY. - 0020-7136 .- 1097-0215. ; 142:11, s. 2254-2262
-
Journal article (peer-reviewed)abstract
- Inflammation is a well-documented driver of cancer development and progression. However, little is known about its role in prostate carcinogenesis. Thus, we examined the association of C-reactive protein (CRP), haptoglobin, albumin and white blood cells (WBC) with prostate cancer (PCa) severity (defined by PCa risk category and clinicopathological characteristics) and progression (defined by PCa death). We selected 8,471 Swedish men with newly diagnosed PCa who had exposure measurements taken approximately 14 years prior to diagnosis. We calculated odds ratio (OR) and 95% confidence interval (CI) for the associations between the inflammatory markers and PCa severity using logistic regression, while Cox proportional hazard regression was used for the associations with overall and PCa death. Serum CRP levels were associated with increased odds of high risk and metastatic PCa, and high PSA levels (20 mu g/L) (OR: 1.29; 95% CI: 1.06-1.56, 1.32; 1.05-1.65 and 1.51; 1.26-1.81, respectively). Similarly, higher haptoglobin levels were associated with increased odds of metastatic PCa, high PSA level and possibly high grade PCa (1.38; 1.10-1.74, 1.50; 1.17-1.93 and 1.25; 1.00-1.56, respectively). Albumin was positively associated with Gleason 4+3 tumour (1.38; 1.02-1.86) and overall death (HRunit increase in log: 1.60; 95% CI: 1.11-2.30), but inversely associated with high risk PCa and high PSA levels (20 mu g/L) (0.71; 0.56-0.89 and 0.72; 0.5 9-0.90). WBC was associated with increased odds of T3-T4 PCa. Except for albumin, none of these markers were associated with PCa death or overall death. Systemic inflammation as early as 14 years prior to diagnosis may influence prostate cancer severity. What's new? High levels of C-reactive protein can presage a particularly malignant prostate cancer, new results show. Cancers certainly arise in the wake of chronic inflammation, but it's not known exactly how markers of inflammation initiate prostate cancer. Here, the authors show that systemic inflammation can worsen the severity of the cancer, even if it occurred long before the cancer's onset. High levels of CRP and haptoglobin, they found, were associated with prostate cancer with high PSA and metastasis. The question remains whether inflammation pushes cancer cells into a more malignant mode, or selects for the more dangerous cells early on.
|
|
| 26. |
- Borochova, K, et al.
(author)
-
Features of the Human Antibody Response against the Respiratory Syncytial Virus Surface Glycoprotein G
- 2020
-
In: Vaccines. - : MDPI AG. - 2076-393X. ; 8:2
-
Journal article (peer-reviewed)abstract
- Respiratory syncytial virus (RSV) infections are a major cause of serious respiratory disease in infants. RSV occurs as two major subgroups A and B, which mainly differ regarding the surface glycoprotein G. The G protein is important for virus attachment and G-specific antibodies can protect against infection. We expressed the surface-exposed part of A2 strain-derived G (A2-G) in baculovirus-infected insect cells and synthesized overlapping peptides spanning complete A2-G. The investigation of the natural IgG response of adult subjects during a period of one year showed that IgG antibodies (i) recognize G significantly stronger than the fusion protein F0, (ii) target mainly non-conformational, sequential peptide epitopes from the exposed conserved region but also buried peptides, and (iii) exhibit a scattered but constant recognition profile during the observation period. The IgG subclass reactivity profile (IgG1 > IgG2 > IgG4 = IgG3) was indicative of a mixed Th1/Th2 response. Two strongly RSV-neutralizing sera including the 1st WHO standard contained high IgG anti-G levels. G-specific IgG increased strongly in children after wheezing attacks suggesting RSV as trigger factor. Our study shows that RSV G and G-derived peptides are useful for serological diagnosis of RSV-triggered exacerbations of respiratory diseases and underlines the importance of G for development of RSV-neutralizing vaccines.
|
|
| 27. |
- Broadaway, K Alaine, et al.
(author)
-
Loci for insulin processing and secretion provide insight into type 2 diabetes risk.
- 2023
-
In: American Journal of Human Genetics. - : Elsevier. - 0002-9297 .- 1537-6605. ; 110:2, s. 284-299
-
Journal article (peer-reviewed)abstract
- Insulin secretion is critical for glucose homeostasis, and increased levels of the precursor proinsulin relative to insulin indicate pancreatic islet beta-cell stress and insufficient insulin secretory capacity in the setting of insulin resistance. We conducted meta-analyses of genome-wide association results for fasting proinsulin from 16 European-ancestry studies in 45,861 individuals. We found 36 independent signals at 30 loci (p value < 5 × 10-8), which validated 12 previously reported loci for proinsulin and ten additional loci previously identified for another glycemic trait. Half of the alleles associated with higher proinsulin showed higher rather than lower effects on glucose levels, corresponding to different mechanisms. Proinsulin loci included genes that affect prohormone convertases, beta-cell dysfunction, vesicle trafficking, beta-cell transcriptional regulation, and lysosomes/autophagy processes. We colocalized 11 proinsulin signals with islet expression quantitative trait locus (eQTL) data, suggesting candidate genes, including ARSG, WIPI1, SLC7A14, and SIX3. The NKX6-3/ANK1 proinsulin signal colocalized with a T2D signal and an adipose ANK1 eQTL signal but not the islet NKX6-3 eQTL. Signals were enriched for islet enhancers, and we showed a plausible islet regulatory mechanism for the lead signal in the MADD locus. These results show how detailed genetic studies of an intermediate phenotype can elucidate mechanisms that may predispose one to disease.
|
|
| 28. |
- Brynhildsen, Jan, 1962-, et al.
(author)
-
Does the menstrual cycle and use of oral contraceptives influence the risk of low back pain? : A prospective study among female soccer players
- 2007
-
In: Scandinavian Journal of Medicine and Science in Sports. - : John Wiley & Sons. - 0905-7188 .- 1600-0838. ; 7:6, s. 348-353
-
Journal article (peer-reviewed)abstract
- Female sex hormones have been suggested to affect the risk of low back pain. One reason is the fact that back pain is a very common symptom during pregnancy. It also seems to be a more common problem among female than male athletes, e.g. in soccer. Although there are few scientific data supporting a relationship between female sex hormones, use of oral contraceptives and low back pain, many doctors and physiotherapists advise women with low back pain to avoid oral contraceptives. The aim of this study was to evaluate whether low back pain fluctuated during the menstrual cycle and differed between women using and not using oral contraceptives. A questionnaire was sent to 12 female soccer teams; 261 players answered and 50 players (28 with back pain and 22 controls) fulfilled the prospective study. At baseline the players underwent a thorough clinical examination and then filled in a diary concerning menstrual data, back pain, training and matches during one season. A total of 296 menstrual cycles was analysed. No difference in prevalence or severity of back pain was seen between the different phases of the menstrual cycle or between users and non-users of oral contraceptives. Our data do not support the hypothesis that low back pain is influenced by hormonal fluctuations during the menstrual cycle or by use of oral contraceptives.
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- Chen, W., et al.
(author)
-
Electronic and geometric structure of clean Pt3Ti(111)
- 1994
-
In: Physical Review B. - 0163-1829 .- 1095-3795. ; 50:8, s. 5620-5627
-
Journal article (peer-reviewed)abstract
- Photoemission spectra and scanning tunneling microscopy (STM) images of the clean Pt3Ti(111) surface are presented. Grazing-emission core-level spectra show that the topmost layer is pure platinum, modified compared with the Pt(111) surface. The Pt 4f levels at the surface are shifted 0.4 eV toward the Fermi level relative to bulk Pt3Ti while the Pt 4f and Ti 2p levels in the bulk are shifted 0.4 and 1.3 eV to higher binding energy relative to pure bulk platinum and titanium, respectively, Tunneling measurements show a surface with only metallic atoms and a small p(2×2) buckling. Our observations of molecularly adsorbed CO are not compatible with metallic titanium atoms at the surface and the STM data thus indirectly confirm that only platinum atoms are present in the topmost layer. Linear muffin-tin-orbital calculations of the bulk band structure and valence-band photoemission spectra reveal highly hybridized electron states between the Pt d and Ti d levels. The calculations give a minor charge transfer from Ti to Pt, 0.37 electrons per Ti atom, but the large core-level shifts reflect the stability of the alloy and the response to the excitation rather than the amount of charge transfer. The observed segregation of platinum to the surface and the altered electronic structure of the topmost layer, due to interaction with the underlying alloy, are in full agreement with earlier conclusions based on low-energy electron-diffraction measurements and on the chemical properties of the surface. © 1994 The American Physical Society.
|
|
| 32. |
- Chen, W., et al.
(author)
-
Redox properties of titanium oxides on Pt3Ti
- 1995
-
In: Journal of Physical Chemistry. - : American Chemical Society (ACS). - 0022-3654 .- 1541-5740. ; 99:34, s. 12892-12895
-
Journal article (peer-reviewed)abstract
- The morphology and electronic structure of surface-segregated titanium oxides on Pt3Ti(111) are presented. Core level photoemission spectra at grazing emission reveal two states of oxidation: a dominant and reducible four-valent oxide together with a small amount of a three-valent oxide is produced by oxidation in 0 2 at and below 400°C; an irreducible three-valent oxide by oxidation in 02 at and above 450 °C. The ratio between the active four-valent and the inactive three-valent oxides decreases with increasing oxidation temperature. The probability for reduction by CO is almost unity for the Ti 4+ oxide, and the conclusion must be that the four-valent oxide plays an active role for catalytic reactions. Scanning tunneling measurements relate these observations to changes in the dispersion and nucleation of the oxide overlayer. The four-valent oxide grows as islands with remaining areas open for CO adsorption while the three-valent oxide spreads on and blocks the crystal surface. Photoemission spectra relate these dispersion effects to an electronic interaction between the Ti 3+ oxide and adjacent Pt atoms. The above observations are in accordance with the common picture of dispersion effects in titania-supported SMSI catalysts and prove that interfacial energies play a crucial role whether the dominant phase is metallic or an oxide.
|
|
| 33. |
- Ch'ng, JH, et al.
(author)
-
Enhanced virulence of Plasmodium falciparum in blood of diabetic patients
- 2021
-
In: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 16:6, s. e0249666-
-
Journal article (peer-reviewed)abstract
- Rising prevalence of diabetes in sub-Saharan Africa, coupled with continued malaria transmission, has resulted more patients dealing with both communicable and non-communicable diseases. We previously reported that travelers with type 2 diabetes mellitus (T2DM) infected with Plasmodium falciparum were three times more likely to develop severe malaria than non-diabetics. Here we explore the biological basis for this by testing blood from uninfected subjects with type 1 and type 2 diabetes, ex vivo, for their effects on parasite growth and rosetting (binding of infected erythrocytes to uninfected erythrocytes). Rosetting was associated with type 2 diabetes, blood glucose and erythrocyte sedimentation rate (ESR), while parasite growth was positively associated with blood glucose, glycated hemoglobin (HbA1c), body mass index (BMI), fibrinogen and triglycerides. This study establishes a link between diabetes and malaria virulence assays, potentially explaining the protective effect of good glycemic control against severe malaria in subjects with diabetes.
|
|
| 34. |
|
|
| 35. |
|
|
| 36. |
|
|
| 37. |
|
|
| 38. |
|
|
| 39. |
- Gauthier, Y., et al.
(author)
-
Reconstruction of the Pt50Ni50(100) surface : a LEED and STM study
- 1995
-
In: Surface Science. - 0039-6028. ; 327:1-2, s. 100-120
-
Journal article (peer-reviewed)abstract
- The structure of the Pt50Ni50(100) surface was investigated by low energy electron diffraction (LEED) and scanning tunnelling spectroscopy (STM). Superstructures corresponding to 12 × 1 and 19 × 1 reconstructions were observed in the LEED pattern, and these reconstructions were identified with atomic resolution by STM. The reconstructed surface layer has a quasi-hexagonal atomic mesh with almost (111) atomic density and is divided into terraces and domains the size of which can be more than a thousand ångströms. The domains are corrugated with protrusions made up by 5 × 1 subunits of the quasi-hexagonal mesh and with valleys containing depressed atoms or 2 × 1 subunits. The 12 × 1 and 19 × 1 periodicities are determined by the sequence of valleys; depending on the thermal treatment, one or the other dominates but both generally coexist on the terrace. Owing to the complexity of the structure, LEED calculations were performed for a simplified model with surface atoms situated in a planar net and uniform quasi-hexagonal meshes. We find that in both reconstructions the two surface layers are significantly enriched with platinum. The top layer enrichment is consistent with previous Auger measurements. © 1995.
|
|
| 40. |
- Gholami, M., et al.
(author)
-
Alternation of band gap and localization of excitons in InGaNAs nanostructures with low nitrogen content
- 2008
-
In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 19:31
-
Journal article (peer-reviewed)abstract
- Continuous wave photoluminescence (cw PL) spectroscopy has been used to study the optical properties of a set of InGaNAs epilayers and single quantum wells with nitrogen concentration less than a few per cent at different temperatures and different excitation powers. We found that nitrogen has a critical role on the emission light of InGaNAs nanostructures and the recombination mechanism. The incorporation of a few per cent of nitrogen leads to shrinkage of the InGaNAs band gap. The physical origin of such band gap reduction has been investigated both experimentally and theoretically by using a band anticrossing model. We have found that localization of excitons that have been caused by incorporation of a few per cent of nitrogen in these structures is the main explanation of such anomalous behavior observed in the low-temperature photoluminescence spectra of these nanostructures. The localization energies of carriers have been evaluated by studying the variation of the quantum well (QW) emission versus temperature, and it was found that the localization energy increases with increasing nitrogen composition. Our data also show that, with increasing excitation intensity, the PL peak position moves to higher energies (blue shift) due to the filling of localized states and capture centers for excitons by photo-generated carriers.
|
|
| 41. |
- Gholami, M., et al.
(author)
-
Evaluation of optical quality and properties of Ga0.64In0.36N0.006As0.994 lattice matched to GaAs by using photoluminescence spectroscopy
- 2009
-
In: Opto-Electronics Review. - : Polish Academy of Sciences Chancellery. - 1230-3402 .- 1896-3757. ; 17:3, s. 260-264
-
Journal article (peer-reviewed)abstract
- We have investigated optical properties of Ga0.64In0.36N0.006As0.994/GaAs single quantum-well structures using photoluminescence technique. We have found that nitrogen creates potential fluctuations in the InGaNAs structures, so it is the cause of trap centres in these structures and leads to localized excitons recombination dynamics. The near-band edge PL at 2 K exhibited a blueshift with an increase in excitation intensity of a sample but there is not such a shift in the PL peak position energy of same sample at 150 K. It has been found that PL spectra have a large full width at half maximum (FWHM) value at 2 K. These results are discussed in terms of carrier localization. Additionally, our results suggest decreasing PL integrated intensity in this structure, possibly due to non-radiative recombination. It has been shown that thermal annealing reduces the local strain created by nitrogen. By annealing process, a blue shifted emission can be observed.
|
|
| 42. |
|
|
| 43. |
- GOTHELID, M, et al.
(author)
-
ADSORPTION OF TIN ON THE GE(111)-C(2X8) SURFACE STUDIED WITH SCANNING-TUNNELING-MICROSCOPY AND PHOTOELECTRON-SPECTROSCOPY
- 1995
-
In: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 328:1-2, s. 80-94
-
Journal article (peer-reviewed)abstract
- The growth and epitaxy of Sn on Ge(111) have been investigated using scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and core level photoelectron spectroscopy for coverages ranging from 0.4 monolayers (ML) to above the critical coverage at 1.6 ML. At the lowest coverage a (root 3 X root 3)R30 degrees reconstruction is formed at an annealing temperature of 250-300 degrees C while an annealing above 500 degrees C creates a dimer-adatom-stacking fault (DAS) (7 X 7) structure. In the (7 X 7) structure we argue that Sn occupies both adatom and dimer sites. A previously suggested difference in the (root 3 X root 3)R30 degrees reconstruction at different coverages could not be revealed in our STM images and it seems likely that the structure is the same both at 0.4 and 0.7 ML Sn coverage. We also report the observation of a new superstructure, a (4 X root 7) reconstruction in the submonolayer regime, which appears as a minority structure in disordered regions adjacent to a (5 X 5) DAS structure, Finally in the post-monolayer region a (3 X 2 root 3) structure, surrounded by vast areas of an amorphous tin overlayer, has been imaged by STM. As the coverage was increased, the amorphous layer completely covered the ordered (3 X 2 root 3) phase, which still could be observed in LEED. Additional room temperature deposition of Sn deteriorated the fractional order LEED spots presumably due to indiffusion of Sn from the interface as the critical coverage was surpassed.
|
|
| 44. |
- GOTHELID, M, et al.
(author)
-
SN-INDUCED SURFACE RECONSTRUCTIONS ON THE GE(111) SURFACE STUDIED WITH SCANNING TUNNELING MICROSCOPY
- 1992
-
In: Surface Science. - 0039-6028 .- 1879-2758. ; 271:3, s. L357-L361
-
Journal article (peer-reviewed)abstract
- Scanning tunneling microscopy (STM) has been used to study different Sn induced reconstructions on the Ge(111) surface; namely the (7 x 7), (5 x 5) and (square-root 3 x square-root 3)R30-degrees structures. The first two have been confirmed to be of the dimer adatom stacking fault (DAS) type with adatoms mainly being Sn. The (square-root 3 x square-root 3)R30-degrees superstructure was found at different Sn depositions. At 0.4 monolayer (ML) Sn coverage a homogeneous Sn adatom layer is adsorbed on the (1 x 1) surface in threefold sites directly over second-layer atoms (T4), while at low coverage, 0.1 ML, the top layer is a mixture of Sn and Ge atoms. We also propose the chemical identities of the different atoms seen in the STM images as related to their apparent height.
|
|
| 45. |
- GOTHELID, M, et al.
(author)
-
STRUCTURAL AND ELECTRONIC EVOLUTION ON THE GE(111)-AG SURFACE
- 1995
-
In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 52:19, s. 14104-14110
-
Journal article (peer-reviewed)abstract
- High-resolution core-level photoelectron spectroscopy has been used to study three different silver induced surface reconstructions on the Ge(111) surface. At the lowest coverage a (4 X 4) structure is formed, which displays a similar Ge 3d core-level line shape as the clean c(2 X 8) surface. Details in the spectra are discussed with respect to possible models. The Ge(111)-Ag (root 3 X root 3)R30 degrees structure Ge 3d spectrum is dominated by a very strong contribution assigned to the two topmost Ge layers in a missing top layer structure, similar to the Si(111)-Ag (root 3 X root 3)R30 degrees surface. A weak bulk peak is present on the high-binding-energy side of the spectrum, while a third contribution assigned to Ge in phase boundaries is included in the fit on the lower-binding-energy side. A comparison with results obtained from the Ge(111)-Au root 3 structure points to substantial differences between the two noble-metal-induced root 3 reconstructions on the Ge(111) surface. Finally, after further deposition of silver at room temperature, the root 3 geometry is locally broken creating a (6 X 6) structure and a new surface-related peak emerges on the low-binding-energy side of the Ge 3d spectrum, which was interpreted as being due to Ge atoms floating on top of the outermost surface layer. The valence band also revealed the existence of small metallic silver islands.
|
|
| 46. |
|
|
| 47. |
- Göthelid, M., et al.
(author)
-
Sn-induced surface reconstructions on the Ge(111) surface studied with scanning tunneling microscopy
- 1992
-
In: Surface Science. - 0039-6028. ; 271:3, s. L357-L361
-
Journal article (peer-reviewed)abstract
- Scanning tunneling microscopy (STM) has been used to study different Sn induced reconstructions on the Ge(111) surface; namely the (7 × 7), (5 × 5) and ( 3 × 3) R30° structures. The first two have been confirmed to be of the dimer adatom stacking faults (DAS) type with adatoms mainly being Sn. The ( 3 × 3)R30° superstructure was found at different Sn depositions. At 0.4 monolayer (ML) Sn coverage a homogeneous Sn adatom layer is adsorbed on the(1 × 1) surface in threefold sites directly over second-layer atoms (T4), while at low coverage, 0.1 ML, the top layer is a mixture of Sn and Ge atoms. We also propose the chemical identities of the different atoms seen in the STM images as related to their apparent height. © 1992.
|
|
| 48. |
- Haghighi, Mona, et al.
(author)
-
A Comparison of Rule-based Analysis with Regression Methods in Understanding the Risk Factors for Study Withdrawal in a Pediatric Study
- 2016
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Journal article (peer-reviewed)abstract
- Regression models are extensively used in many epidemiological studies to understand the linkage between specific outcomes of interest and their risk factors. However, regression models in general examine the average effects of the risk factors and ignore subgroups with different risk profiles. As a result, interventions are often geared towards the average member of the population, without consideration of the special health needs of different subgroups within the population. This paper demonstrates the value of using rule-based analysis methods that can identify subgroups with heterogeneous risk profiles in a population without imposing assumptions on the subgroups or method. The rules define the risk pattern of subsets of individuals by not only considering the interactions between the risk factors but also their ranges. We compared the rule-based analysis results with the results from a logistic regression model in The Environmental Determinants of Diabetes in the Young (TEDDY) study. Both methods detected a similar suite of risk factors, but the rule-based analysis was superior at detecting multiple interactions between the risk factors that characterize the subgroups. A further investigation of the particular characteristics of each subgroup may detect the special health needs of the subgroup and lead to tailored interventions.
|
|
| 49. |
|
|
| 50. |
|
|
