Alternative Buffer-Layers for the Growth of SrBi2Ta2O9 on Silicon

In this work we investigate the influence of the use of YSZ and CeO2/YSZ as insulators for Metal- Ferroelectric-Insulator-Semiconductor (MFIS) structures made with SrBi2Ta2O9 (SBT). We show that by using YSZ only the a-axis oriented Pyrochlore phase could be obtained. On the other hand the use of a CeO2/YSZ double-buffer layer gave a c-axis oriented SBT with no amorphous SiO2 inter- diffusion layer. The characteristics of MFIS diodes were greatly improved by the use of the double buffer. Using the same deposition conditions the memory window could be increased from 0.3 V to 0.9 V. From the piezoelectric response, nano-meter scale ferroelectric domains could be clearly identified in SBT thin films.Comment: 5 pages, 9 figures, 13 refernece

Anti-ganglioside antibodies and celiac disease

We describe our own experience on the prevalence of a wider range of anti-ganglioside antibodies and their clinical significance in CD patients. Using a commercially available ELISA kit (IMMCO Diagnostics, Buffalo, NY, USA), we studied anti-GM1, anti-GD1b, and anti-GQ1b serum IgG and IgM antibodies in 22 adult patients (median age 35, range: 19–56 years; three males, 19 females) with CD and neurological manifestations, including eight cases of idiopathic cerebellar ataxia, seven cases with epilepsy (without cerebral calcifications), two with multiple sclerosis, three with attention/memory impairment, and two with peripheral neuropathies. In all cases, diagnosis of CD was confirmed by endoscopic duodenal biopsy, revealing different grades of villous atrophy (from 3a to 3c, according to the modified Marsh classification). In all CD patients, intestinal villous atrophy was associated with a positivity for serological CD markers (anti-endomysial and/or anti-tissue transglutaminase antibodies) further supporting the diagnosis of CD. All available data, regarding CD diagnosis, diagnostic work-up, histopathology and treatment were obtained from the hospital digital database

Current guidelines for the management of celiac disease: A systematic review with comparative analysis

Wheat and other gluten-containing grains are widely consumed, providing approximately 50% of the caloric intake in both industrialised and developing countries. The widespread diffusion of gluten-containing diets has rapidly led to a sharp increase in celiac disease prevalence. This condition was thought to be very rare outside Europe and relatively ignored by health professionals and the global media. However, in recent years, the discovery of important diagnostic and pathogenic milestones has led to the emergence of celiac disease (CD) from obscurity to global prominence. These modifications have prompted experts worldwide to identify effective strategies for the diagnosis and follow-up of CD. Different scientific societies, mainly from Europe and America, have proposed guidelines based on CD's most recent evidence

Radio-to-UV monitoring of AO 0235+164 by the WEBT and Swift during the 2006--2007 outburst

The blazar AO 0235+164 was claimed to show a quasi-periodic behaviour in the radio and optical bands. Moreover, an extra emission component contributing to the UV and soft X-ray flux was detected, whose nature is not yet clear. A predicted optical outburst was observed in late 2006/early 2007. We here present the radio-to-optical WEBT light curves during the outburst, together with UV data acquired by Swift in the same period. We found the optical outburst to be as strong as the big outbursts of the past: starting from late September 2006, a brightness increase of 5 mag led to the outburst peak in February 19-21, 2007. We also observed an outburst at mm and then at cm wavelengths, with an increasing time delay going toward lower frequencies during the rising phase. Cross-correlation analysis indicates that the 1 mm and 37 GHz flux variations lagged behind the R-band ones by about 3 weeks and 2 months, respectively. These short time delays suggest that the corresponding jet emitting regions are only slightly separated and/or misaligned. In contrast, during the outburst decreasing phase the flux faded contemporaneously at all cm wavelengths. This abrupt change in the emission behaviour may suggest the presence of some shutdown mechanism of intrinsic or geometric nature. The behaviour of the UV flux closely follows the optical and near-IR one. By separating the synchrotron and extra component contributions to the UV flux, we found that they correlate, which suggests that the two emissions have a common origin.Comment: 9 pages, 7 figures, in press for Astronomy and Astrophysic

Silicon microcantilever sensors to detect the reversible conformational change of a molecular switch, Spiropyan

The high sensitivity of silicon microcantilever sensors has expanded their use in areas ranging from gas sensing to bio-medical applications. Photochromic molecules also represent promising candidates for a large variety of sensing applications. In this work, the operating principles of these two sensing methods are combined in order to detect the reversible conformational change of a molecular switch, spiropyran. Thus, arrays of silicon microcantilever sensors were functionalized with spiropyran on the gold covered side and used as test microcantilevers. The microcantilever deflection response was observed, in five sequential cycles, as the transition from the spiropyran (SP) (CLOSED) to the merocyanine (MC) (OPEN) state and vice-versa when induced by UV and white light LED sources, respectively, proving the reversibility capabilities of this type of sensor. The microcantilever deflection direction was observed to be in one direction when changing to the MC state and in the opposite direction when changing back to the SP state. A tensile stress was induced in the microcantilever when the SP to MC transition took place, while a compressive stress was observed for the reverse transition. These different type of stresses are believed to be related to the spatial conformational changes induced in the photochromic molecule upon photo-isomerisation

Anhydrous Calcium Oxalate Polymorphism: A Combined Computational and Synchrotron X-ray Diffraction Study

Four possible models for anhydrous calcium oxalate (COA) polymorphs have been investigated through ab initio quantum mechanical methods. Their structural properties, infrared and Raman spectra, and thermodynamic stability in the range of 0–800 K have been analyzed and compared. Along with the known β-COA structure, two models turn out to be possible candidates for the α- and γ-polymorphs that were observed during dehydration of weddellite (calcium oxalate dihydrate, COD) by Walter-Lévy and Laniepce ( C. R. Acad. Sci. Paris 1964, 259, 4685). While the calculated vibrational frequencies show that the four COA models correspond to minimum energy structures, β-COA is the thermodynamically favored phase over the range of temperatures examined in the present study. Despite the fact that computed vibrational spectra and X-ray diffraction (XRD) patterns of these polymorphs exhibit some different features, a definitive assignment of the structures based on computational results is not possible due to the lack of accurate experimental data. In an effort to improve comparative experimental data, the structural evolution of whewellite (calcium oxalate monohydrate, COM) has been probed using time-resolved synchrotron X-ray diffraction, in order to correlate the calculated structures to the observed structures. The evolution has been shown to go through at least four phases identified as COM, α-COA (corresponding to one of the models proposed by computation), β-COA, and CaCO3. The reactions are predominantly two-phase reactions, and at 140 °C evidence of three-phase coexistence has been noted between COM, α-COA, and β-COA. The time-resolved XRD data allow estimation of the kinetics of the reactions; these indicate second-order reactions between COM and α-COA and zeroth-order reactions between α-COA and β-COA