Role of structural disorder in the vibrational spectra of sol-gel γ and δ-Al2O3 nanoparticles.

Alumina nanopowders belonging to the γ and δ transition phases have been characterized by infrared and Raman spectroscopies. A quantitative interpretation of their vibrational spectra has been provided and related to their crystal structure, with particular emphasis on structural disorder and features not predicted by group-theoretical considerations. Both phases show very similar infrared dielectric functions, but with clear instances of mode-splitting in the δ phase, which are related to ordering in the tetrahedral Al positions. Raman spectroscopy was unable to resolve any modes in the sample identified as γ phase, but the full lattice vibrational region could be measured for the δ sample under UV and red excitation lines. Raman spectra are more complex than those obtained by infrared spectroscopy and cannot be completely explained by factor group analysis, in the absence of dedicated theoretical studies. Finally, the luminescent properties of these materials have been qualitatively explored and linked to disorder and substitutional impurities. In general, the results contained in this work prove that vibrational spectroscopies are powerful tools for quantitative analyses of these disordered nanomaterials and suggest the need for more theoretical work to understand their vibrational properties.

Use of different proportions of rice milling fractions as strategy for improving quality parameters and nutritional profile of gluten-free bread.

The growing consumer exigency and the lack of gluten-free (GF) bakery products with good technological and nutritional characteristics in the market have increase the need of researching in this area. Few studies have analysed the simultaneous influence of different flour fractions from rice dry milling to formulate GF bread and its effects on rheology and product quality. The aim of this study was to characterize the chemical and physical properties of rice milling fractions (flour, coarse, bran); and to evaluate the effect of these fractions on rheology, and quality of GF bread. High fibre content (31.5%) and good hydration and functional properties demonstrated the suitability of bran for food development. A mixture design with three components was used. Pasting parameters, bread specific volume (BSV), firmness and colour intensity (Chr) responses were fitted to linear and quadratic polynomial models. The presence of bran in the blends reduced almost all pasting parameters. The optimal mixture proportion was flour:coarse:bran (45:35:20), presenting a BSV 1.7 ± 0.1 cm3/g; firmness 0.23 ± 0.01 MPa, and Chr 23.8 ± 0.4. A portion (50 g) of GF bread increased four times the dietary fibre intake. The utilization of different rice fractions to formulate GF bread improved the product quality and enhance the nutritional profile.

The functional and organoleptic characterization of a dairy-free dessert containing a novel probiotic food ingredient.

New eating habits and diversification of tastes of consumers have led to the scientific community and the food industry to expand the range of probiotic foods and novel probiotic ingredients. Scant information is available about the viability and functionality of probiotics during shelf life and its effect on the nutritional characteristics of dairy-free products. The aim of the study was to formulate a fermented dairy-free dessert using a novel food ingredient based on a pumpkin by-product and containing Lactobacillus casei (ATCC®393™) (NFI). The effect of NFI and the soluble solids (SS) of soy milk on the probiotic viability, physical stability, colour, and firmness of dairy-free dessert was studied using a response surface methodology. The different levels of SS and NFI significantly (p < 0.05) affected the response variables. Thereafter, two formulations were selected and the physico-chemical, nutritional and organoleptic characterization were evaluated. The L. casei count reached the desired therapeutic level (>107 UFC mL-1) after gastrointestinal digestion at 21 days of storage. In general, both the fermentation process and storage reduced (p < 0.05) the content of phytic acid, raffinose and stachyose, which implies a nutritional improvement of the final product. Scores above 5.0 on a 9-point scale were obtained for colour, odour, texture and overall acceptability in the consumer acceptance test. Therefore, a dairy-free dessert with good physical properties, suitable nutritional characteristics, and sensorial acceptability could be successfully formulated with the NFI.

[Secondary opacification of hydrophilic acrylic intraocular lenses: report of two cases]. / Opacification secondaire d'implants intraoculaires acryliques hydrophiles : à propos de deux cas.

PURPOSE: To describe two cases of secondary opacification of hydrophilic acrylic IOLs after vitreoretinal surgery. METHODS: Analysis of IOL deposits with anterior segment optical coherence tomography (OCT Visante(®)) and high-frequency ultrasound biomicroscopy (CineScan HF, Quantel Medical(®)) was carried out preoperatively. The explanted IOLs were analyzed with optical and electron microscopy, and energy dispersive spectrometry (EDS). RESULTS: In both patients, the deposits were located on the surface and within the implant and were composed of calcium phosphate crystals. Vitreoretinal surgery performed a few months prior to the secondary opacification was identified as a risk factor. CONCLUSION: When a patient presents with a secondary opacification of the IOL involving the visual axis, explantation is sometimes necessary, fortunately with typically good functional recovery in the postoperative period. While this complication is rare and the exact pathophysiology poorly understood, it must be considered in a pseudophakic patient with an unexplained decrease in visual acuity who has undergone more than one intraocular procedure.

Atomic-scale redistribution of Pt during reactive diffusion in Ni (5% Pt)-Si contacts.

The NiSi silicide that forms by reactive diffusion between Ni and Si active regions of nanotransistors is used nowadays as contacts in nanoelectronics because of its low resistivity. Pt is added to the Ni film in order to stabilise the NiSi phase against the formation of the high-resistivity NiSi(2) phase and agglomeration. In situ X-ray diffraction (XRD) experiments performed on material aged at 350 degrees C (under vacuum) showed the complete consumption of the Ni (5 at% Pt) phase, the regression of Ni(2)Si phase as well as the growth of the NiSi phase after 48 min. Pt distribution for this heat treatment has been analysed by laser-assisted tomographic atom probe (LATAP). An enrichment of platinum in the middle of the NiSi phase suggests that Pt is almost immobile during the growth of NiSi at the two interfaces: Ni(2)Si/NiSi and NiSi/Si. In the peak, platinum was found to substitute for Ni in the NiSi phase. Very small amounts of Pt were also found in the Ni(2)Si phase close to the surface and at the NiSi/Si interface.

Implication of cytochrome P-450 1A isoforms and the AH receptor in the genotoxicity of coal-tar fume condensate and bitumen fume condensates.

During the hot application of bitumen- or coal-tar-containing materials, fumes are emitted that contain polycyclic aromatic compounds. Although workers' exposure to these fumes is low, it might lead to health problems. No study has reported the metabolic pathways involved in the genotoxicity of coal tar or bitumen fume condensates (CTFC, BFCs). We have therefore studied the DNA adducts formed by incubation of CTFC or BFCs with liver microsomes from several type of mice and with yeast microsomes expressing individual human CYP enzymes. Our results demonstrates that: (1) the aryl hydrocarbon receptor (AHR) plays an important role in the biotransformation of BFCs and to a lesser extent of CTFC; (2) for CTFC, both cytochrome P450 (CYP) 1A isoforms are involved in the formation of genotoxic compounds, and the reactive metabolites formed via CYP 1A1, are substrates for epoxide hydrolase (mEH); (3) for BFCs, the genotoxicity is partially dependent upon CYP 1A1 and the reactive metabolites are not substrates for mEH; (4) CYP 1A isoforms are not exclusively responsible for the genotoxicity of the CTFC and BFCs as other CYPs and also enzymes of the [AH] gene battery, may play an important role.

In vitro studies of the genotoxic effects of bitumen and coal-tar fume condensates: comparison of data obtained by mutagenicity testing and DNA adduct analysis by 32P-postlabelling.

Bitumens contain traces of polycyclic aromatic compounds (PACs), a part of which will end up in the fumes emitted during hot handling of bitumen-containing products, e.g. during roadpaving. Although exposure of workers to these fumes is low, it might lead to health problems. Studies on bitumen fume condensates (BFCs) showed weak to moderate mutagenic activities, but studies on DNA adduct formation have not been reported. Therefore, a study was initiated in which fumes were generated from two road grade bitumens, in such a way that they were representative of the fumes produced in the field. The combined vapour/particulates were tested in vitro for their ability to produce DNA adducts and in modified Ames mutation assays, using a number of different strains. An attempt was made to relate the results to chemical data, such as the content of a number of individual polycyclic aromatic hydrocarbons (PAHs) and with a measure for the total PAC content. As a reference material fume condensate from coal-tar (coal-tar pitch volatiles; CTPV) were subjected to the same tests. All fume condensates tested were mutagenic to all strains and induced the formation of DNA adducts. The patterns of DNA adducts, obtained by 32P-postlabelling, arising from the BFCs were qualitatively different from the patterns of adducts obtained from the CTPVs, implying qualitative differences in the nature of the compounds responsible for the formation of these adducts. This is corroborated by the observation that for BFCs quantitative adduct levels are higher than would be expected based on the PAH content. These data thus indicate that the PAHs analysed are not the sole components responsible for adduct formation from BFCs, but that an important contribution comes from other (hetero- and/or substituted-) PACs.