The emergence of biobanks: practical design considerations for large population-based studies of gene-environment interactions

The completion of the human genome project has spurred new thinking about launching large-scale cohort studies; as proposed, these studies will differ from past large-scale cohort studies and will focus primarily on how genetic variation interacts with environmental exposures to affect the risk for common human diseases. There is no single 'best design' for large-scale studies of gene-environment interactions. Some studies are best performed in cohort studies where unbiased information can be collected on individuals years before disease onset. Other studies may be most efficiently done with a case-control design using currently available automated data. Population-based biobanks with nested case-control or case-cohort studies offer distinct advantages to some of the resource-intensive large-scale cohort studies under consideration, and may be more acceptable to many of the countries around the world currently considering such projects.     

Effect of three-body forces on the lattice dynamics of noble metals

A simple method to generate an effective electron-ion interaction pseudopotential from the energy wave number characteristic obtained by first principles calculations has been suggested. This effective potential has been used, in third order perturbation, to study the effect of three-body forces on the lattice dynamics of noble metals. It is found that three-body forces, in these metals, do play an important role. The inclusion of such three-body forces appreciably improves the agreement between the experimental and theoretical phonon dispersion curves.     

An ultra-low hydrolysis sol-gel route for titanosilicate xerogels and their characterization

In this work TiO₂-SiO₂ xerogels were prepared through an ultra low hydrolysis method using titanium and silicon alkoxide. The samples were heat treated to 500°C. The xerogels were characterized using TGA/DTA, FTIR, XRD and TEM. The samples showed the formation of Si–O–Ti bridges by its characteristic vibration within 925–960 cm⁻¹ range. Si–O–Si bond angles were calculated using the central force network model. The TiO₂ in all the samples crystallized on heat treatment to 500°C. The crystallite size calculated using the Scherer formula from the XRD was verified from the Transmission Electron Micrograph. Samples heat treated to 350°C remained amorphous and hence could be used as hosts for biomaterials and organic optical materials.     

Cobalt-supported alumina as catalytic film prepared by electrophoretic deposition for hydrogen release applications

Shaped catalysts are crucial for technological applications. In this context, we have developed Co-αAl₂O₃ catalyst films deposited over Cu plates to be used in hydrogen generation by hydrolysis of sodium borohydride NaBH₄ in alkaline solution. The Co-αAl₂O₃ films were prepared by electrophoretic deposition according to six different routes. While five of them failed in fabricating adhering films, the sixth route, consisting of electrodepositing Co-impregnated αAl₂O₃, showed promising results. The as-obtained shaped catalysts were stable when hydrogen vigorously bubbled and catalyzed the NaBH₄ hydrolysis with attractive hydrogen generation rates. These results open an alternative route for preparing shaped catalysts in this reaction.     

Thermoluminescence response of the larimar rocks

The aim of this paper is to evaluate the thermoluminescent (TL) response of a larimar, a variety of pectolite (NaCa₂Si₃O₈[OH]). It is a blue pectolite only found on the terrestrial crust of the province of Barahona, in the south-western region of the Dominican Republic. The larimar rock used in this study, presented a light-blue color with brown areas. X-ray powder diffractometry (XRD), showed that the light-blue portion of the rock is composed essentially by pectolite and the brown portion is composed by a mixture of minerals. Aliquots of 5 mg of light-blue portions were irradiated with gamma rays with doses from 10 to 10⁴ Gy and the TL glow curves were obtained from 50 to 400 °C. The glow curve showed a broad peak around 150 °C and a peak near 280 °C. Different pre-heat condition were used to remove the broad peak. The TL emission of the main peak appeared in the region of 580 nm. The TL response of the main peak showed a linear behavior up to 2500 Gy and a sub-linear behavior above this dose value. Studies of the 30 day fading effects in TL signal using a pre-heating temperature around 180 °C during 15 min were carried out and fading near 25% was observed.     

Phenolic Compounds Recovery from Blood Orange Peels Using a Novel Green Infrared Technology Ired-Irrad®, and Their Effect on the Inhibition of Aspergillus flavus Proliferation and Aflatoxin B1 Production

The intensification of total phenolic compound (TPC) extraction from blood orange peels was optimized using a novel green infrared-assisted extraction technique (IRAE, Ired-Irrad^®) and compared to the conventional extraction using a water bath (WB). Response surface methodology (RSM) allowed for the optimization of ethanol concentration (E), time (t), and temperature (T) in terms of extracted TPC and their antiradical activity, for both WB extraction and IRAE. Using WB extraction, the multiple response optimums as obtained after 4 h at 73 °C and using 79% ethanol/water were 1.67 g GAE/100 g for TPC and 59% as DPPH inhibition percentage. IRAE increased the extraction of TPC by 18% using 52% ethanol/water after less than 1 h at 79 °C. This novel technology has the advantage of being easily scalable for industrial usage. HPLC analysis showed that IRAE enhanced the recovery of gallic acid, resveratrol, quercetin, caffeic acid, and hesperidin. IR extracts exhibited high bioactivity by inhibiting the production of Aflatoxin B1 by 98.9%.     

Liquid chromatographic/electrospray ionization mass spectrometric identification of the oxidation end-products of metformin in aqueous solutions

Metformin is an antihyperglycemic drug that exhibits some antioxidant properties. HO*-induced oxidation of metformin was studied in aqueous solution, in both aerated and deaerated conditions. Gamma radiolysis of water was used to generate HO* free radicals, capable of initiating one-electron oxidation of metformin. Oxidation end-products were identified by direct infusion mass spectrometry (MS) and high-performance liquid chromatography/mass spectrometry (HPLC/MSn): for every product, structure elucidation was based on its mass (simple mass spectra confirmed by HPLC/MS). In addition, fragmentation spectra (MS2, MS3 and MS4) and the determination of deuterium-hydrogen exchange sites provided valuable information allowing the complete identification of some of the end-products. At low radiation dose, four products were identified as primary ones, since they result from the direct attack of HO* radicals on metformin. These primary oxidation end-products were identified respectively as hydroperoxide of metformin, covalent dimer of metformin, methylbiguanide and 2-amino-4-imino-5-methyl-1,3,5-triazine. At high radiation dose, seven other products were identified as secondary ones, resulting from the HO*-induced oxidation of the primary end-products. A reaction scheme was postulated for the interpretation of the results.     

Gallium trichloride-catalyzed conjugate addition of indole and pyrrole to α,β-unsaturated ketones in aqueous media

Michael addition of indole and pyrrole to a variety ofα,β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl_3 in aqueous media to afford the corresponding products in good to excellent yields.     

Cosmological tests of gravity

Modifications of general relativity provide an alternative explanation to dark energy for the observed acceleration of the universe. We review recent developments in modified gravity theories, focusing on higher-dimensional approaches and chameleon/f(R) theories. We classify these models in terms of the screening mechanisms that enable such theories to approach general relativity on small scales (and thus satisfy solar system constraints). We describe general features of the modified Friedman equation in such theories.The second half of this review describes experimental tests of gravity in light of the new theoretical approaches. We summarize the high precision tests of gravity on laboratory and solar system scales. We describe in some detail tests on astrophysical scales ranging from ∼ kpc (galaxy scales) to ∼ Gpc (large-scale structure). These tests rely on the growth and inter-relationship of perturbations in the metric potentials, density and velocity fields which can be measured using gravitational lensing, galaxy cluster abundances, galaxy clustering and the integrated Sachs-Wolfe effect. A robust way to interpret observations is by constraining effective parameters, such as the ratio of the two metric potentials. Currently tests of gravity on astrophysical scales are in the early stages — we summarize these tests and discuss the interesting prospects for new tests in the coming decade.