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Vanadium pentoxide (V 2 O 5 ·nH 2 O) 1D-nanostructures as nanowires and nanorods have been obtained by decomposition of vanadium peroxide in hydrothermal conditions. Electron microscopy, Raman spectroscopy, and X-ray absorption spectroscopy (XAS) were employed to characterize the morphology and the local structure of as-obtained samples. Scanning transmission electron microscopy (STEM) revealed that the diameter of the nanowires and nanorods were found to be 10–20 and 30–40 nm, respectively. The results demonstrated that a combination of Raman and XAS techniques allowed the accurate characterization of the local structure of V 2 O 5 1D-nanostructures which are related to different morphologies. Analyses of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra reveals that the local structure of V in the as-obtained samples is similar to the bulk V 2 O 5 (in orthorhombic phase), except for a higher degree of local symmetry within the structure of the VO 5 square pyramid. Additionally, the nanostructures prepared by this technique present a single crystalline nature and could emit visible light at room temperature which is related to the local order of V atoms of the studied samples.

Alzheimer’s disease (AD) is a severe neurodegenerative disorder still in search of effective methods of diagnosis. Altered levels of the NMDA receptor co-agonist, d -serine, have been associated with neurological disorders, including schizophrenia and epilepsy. However, whether d -serine levels are deregulated in AD remains elusive. Here, we first measured D -serine levels in post-mortem hippocampal and cortical samples from nondemented subjects ( n =8) and AD patients ( n =14). We next determined d -serine levels in experimental models of AD, including wild-type rats and mice that received intracerebroventricular injections of amyloid-β oligomers, and APP/PS1 transgenic mice. Finally, we assessed d -serine levels in the cerebrospinal fluid (CSF) of 21 patients with a diagnosis of probable AD, as compared with patients with normal pressure hydrocephalus ( n =9), major depression ( n =9) and healthy controls ( n =10), and results were contrasted with CSF amyloid-β/tau AD biomarkers. d -serine levels were higher in the hippocampus and parietal cortex of AD patients than in control subjects. Levels of both d -serine and serine racemase, the enzyme responsible for d -serine production, were elevated in experimental models of AD. Significantly, d -serine levels were higher in the CSF of probable AD patients than in non-cognitively impaired subject groups. Combining d -serine levels to the amyloid/tau index remarkably increased the sensitivity and specificity of diagnosis of probable AD in our cohort. Our results show that increased brain and CSF d -serine levels are associated with AD. CSF d -serine levels discriminated between nondemented and AD patients in our cohort and might constitute a novel candidate biomarker for early AD diagnosis.

SrTiO3 thin films were prepared by the polymeric precursor method and deposited by spin-coating onto Pt/Ti/SiO2/Si(100) substrates. The spin-coated films heat treated at 700°C were crack-free, dense, and homogeneous. Microstructural and morphological evaluations were followed by grazing incident X-ray, scanning electron microscopy and atomic force microscopy. Dielectric studies indicated a dielectric constant of about 475, which is higher than that of ceramic SrTiO3, and a factor dissipation of about 0.050 at 100 kHz. SrTiO3 thin films were found to have paraelectric properties with C-V characteristics.

Previous studies in dementia epidemiology have reported higher Alzheimer's disease rates in African-Americans when compared with White Americans. To determine whether genetically determined African ancestry is associated with neuropathological changes commonly associated with dementia, we analyzed a population-based brain bank in the highly admixed city of São Paulo, Brazil. African ancestry was estimated through the use of previously described ancestry-informative markers. Risk of presence of neuritic plaques, neurofibrillary tangles, small vessel disease, brain infarcts and Lewy bodies in subjects with significant African ancestry versus those without was determined. Results were adjusted for multiple environmental risk factors, demographic variables and apolipoprotein E genotype. African ancestry was inversely correlated with neuritic plaques ( P =0.03). Subjects with significant African ancestry ( n =112, 55.4%) showed lower prevalence of neuritic plaques in the univariate analysis (odds ratio (OR) 0.72, 95% confidence interval (CI) 0.55–0.95, P =0.01) and when adjusted for age, sex, APOE genotype and environmental risk factors (OR 0.43, 95% CI 0.21–0.89, P =0.02). There were no significant differences for the presence of other neuropathological alterations. We show for the first time, using genetically determined ancestry, that African ancestry may be highly protective of Alzheimer's disease neuropathology, functioning through either genetic variants or unknown environmental factors. Epidemiological studies correlating African-American race/ethnicity with increased Alzheimer's disease rates should not be interpreted as surrogates of genetic ancestry or considered to represent African-derived populations from the developing nations such as Brazil.

SnO2 thin films doped with 7 mol% Sb2O3 were prepared by the polymeric precursor method, and deposited by spin-coating, all of them being deposited on amorphous silica substrate. The effect of thickness on the microstructural, optical and electrical properties were studied. Microstructural characterisation was carried out by XRD and scanning tunnelling microscopy. Electrical resistivity measurements were obtained by the van der Pauw four-probe method. UV-visible spectroscopy and ellipsometry were carried out for the optical characterisation. The films present nanometric grains of the order of 13 nm, and low roughness. The electrical resistivity decreased with the increase of the film thickness and the smallest measured value was 6.5 x 10 exp(-3) Ohm.cm for the 988 nm thick film. The samples displayed a high transmittance value of 80% in the visible region. The obtained results show that the polymeric precursor method is effective for transparent conductive oxide manufacturing. 24 refs.

Nanocrystalline ZrO2-12 mol % CeO2powders were synthesized using a polymeric precursor method based on the Pechini process. X-ray diffraction (XRD) patterns showed that the method was effective to synthesize tetragonal zirconia single-phase. The mean crystallite size attained ranges from 6 to 15 nm. The BET surface areas were relatively high reaching 97 m2/g. Studies by nitrogen adsorption/desorption on powders, dilatometry of the compacts, and transmission electron microscopy (TEM) of the powders, were also developed to verify the particles agglomeration state. Both citric acid : ethylene glycol ratio and calcination temperature affected the powder morphology, which influenced the sinterability and microstructure of the sintered material, as showed by scanning electron microscopy (SEM).

NiTiO 3 (NTO) nanoparticles encapsulated with SiO 2 were prepared by the sol–gel method resulting on core-shell structure. Changes on isoelectric point as a function of silica were evaluated by means of zeta potential. The NTO nanoparticles heat treated at 600°C were characterized by X-ray diffraction, transmission electron microscopy (TEM) and energy dispersive X-ray analysis. TEM observations showed that the mean size of NTO is in the range of 2.5–42.5 nm while the thickness of SiO 2 shell attained 1.5–3.5 nm approximately.

ZrO2 powder was coated with Al2O3 precursor generated by a polymeric precursor method in aqueous solution. The system of nanocoated particles formed a core shell-like structure in which the particle is the core and the nanocoating (additive) is the shell. A new approach is reported in order to control the superficial mass transport and the exaggerated grain growth during the sintering of zirconia powder. Transmission electron microscopy (TEM) observations clearly showed the formation of an alumina layer on the surface of the zirconia particles. This layer modifies the sintering process and retards the maximum shrinkage temperature of the pure zirconia.

We discuss the nature of visible photoluminescence at room temperature in amorphous lead titanate in the light of the results of recent experimental and theoretical calculations. Experimental results obtained by XANES and EXAFS revealed that amorphous lead titanate is composed of a Ti-O network having fivefold Ti coordination and NBO-type (non-bridging oxygen) defects. These defects can modify the electronic structure of amorphous compounds. Our calculation of the electronic structure involved the use of first-principle molecular calculations to simulate the variation of the electronic structure in the lead titanate crystalline phase, which is known to have a direct band gap, and we also made an in-depth examination of amorphous lead titanate. The results of our theoretical calculations of amorphous lead titanate indicate that the formation of fivefold coordination in the amorphous system may introduce delocalized electronic levels in the HOMO (highest occupied molecular orbital) and the LUMO (lowest unoccupied molecular orbital). A comparison of the experimental and theoretical results of amorphous compounds suggests the possibility of a radiative recombination (electron-hole pairs), which may be responsible for the emission of photoluminescence.