Mössbauer spectroscopy of titanium-substituted iron garnets

The Mössbauer spectroscopy of polycrystalline Y_3?x Ca _x Fe_5?x Ti _x O₁₂ (x=0·2, 0·5, 0·7) garnets has been studied at room temperature. The hyperfine fields both at the octahedral and tetrahedral sites decrease with increasing titanium content. The hyperfine fields both ata andd-sites are linearly proportional to magnetization. The quadrupole splitting fora-site shows no dependence on Ti content while the quadrupole splitting ford-site increases slightly withx. The results are explained on the basis of lattice distortion due to Ti substitution ona-site.     

Water absorption behavior of PALF/GF hybrid polyester composites

The water absorption characteristics of pineapple leaf fiber (PALF)/glass fiber (GF) hybrid polyester(PER) composites, and chemically modified PALF/polyester composites were evaluated by immersion in distilled water at 28, 60, and 90°C. The diffusion properties of the intimately mixed (IM) and the layered hybrid composite GPG (Glass skin and PALF core) of different PALF/GF ratio at the three temperatures were compared in order to identify the environmental ageing mechanism at different temperatures. The effect of temperature on the kinetics and thermodynamics of diffusion were also examined. The water uptake of both IM and GPG hybrid composites was decreased with increase in glass fiber content; the lowest water uptake was observed for 0.46 V_f GF hybrid composite. Among the chemically modified composites, vinyl tri 2‐methoxy ethoxy silane treated composites showed the lowest water uptake. Finally, parameters like diffusion, sorption, and permeability coefficients were determined. It was observed that equilibrium water uptake is dependent on the nature of the composite and temperature. Experimental results were also compared with theoretical predictions. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Development of non-perfluorinated hybrid materials for single-cell proton exchange membrane fuel cells

Development of low temperature fuel cells that operate under 100 °C are needed to reduce the costs, to design a class of hybrid membranes and to construct various structures of membrane-electrode-assembles (MEAs) for proton exchange membrane fuel cells (PEMFC). In this work, PVA/PMA/SiO₂ hybrid composite membranes were synthesized and their conductivities were determined by impedance measurements. We found a maximum conductivity value of 4.2 × 10⁻³ S/cm at 80 °C and 100% relative humidity (RH). A fuel cell test evaluation for various MEAs was conducted by the potentiodynamic analysis and the current density values were determined from the current–voltage (I–V) curves. A maximum current density of 635 mA/cm² was obtained at 80 °C and 100% RH. To the best of our knowledge, this is the first time that a high current density of PVA-based electrolytes for PEMFCs operating at low temperature is reported. The structural characters were examined using of XRD and FTIR methods, and thermal properties were studied using DSC and TGA techniques and the results were discussed (cf. supplementation). The present study revealed that the single cell performance depends mainly on the temperature, relative humidity and chemical compositions of the membranes.     

Immunological properties of human decidual macrophages--a possible role in intrauterine immunity

Our aim was to investigate the contribution of decidual macrophages, which constitute an important immune component of the decidua in late gestation, to intrauterine defence mechanisms. Using flow cytometry we examined the ability of decidual macrophages, isolated from term decidua, to bind and phagocytose fluorescence-labelled bacterial and yeast bioparticles. We also assessed their ability to generate superoxide radicals and tumour necrosis factor-alpha following lipopolysaccharide challenge. Decidual macrophages bound bacterial and yeast particles in a dose-dependent manner, which subsequently led to phagocytosis. These macrophages also produced superoxide radicals and the pro-inflammatory cytokine TNF-alpha when challenged with bacterial lipopolysaccharides. These results suggest a role for decidual macrophages in pathogen recognition and clearance during pregnancy, and, therefore, they are likely to protect the fetus against intrauterine infections which might otherwise lead to preterm labour.     

Surface complexation modeling of U(VI) sorption to Hanford sediment with varying geochemical conditions

A series of U(VI) sorption experiments with varying pH, ionic strength, concentrations of dissolved U(VI), and alkalinity was conducted to provide a more realistic database for U(VI) sorption onto near-field vadose zone sediments at the proposed Integrated Disposal Facility (IDF) on the Hanford Site, Washington. The distribution coefficient (Kd) for U(VI) in a leachate that is predicted to result from the weathering of vitrified wastes disposed in the IDF is 0 mL/g due to the high sodium and carbonate concentrations and high pH of the glass leachate. However, when the pH and alkalinity of the IDF sediment native pore water increases during mixing with the glass leachate, U(VI) uptake is observed and the value of the U(VI) Kd increases 4.3 mL/g, because of U(VI) coprecipitation with newly formed calcite. A nonelectrostatic, generalized composite approach for surface complexation modeling was applied and a combination of two U(VI) surface species, monodentate (SOUO2+), and bidentate (SO2UO2(CO3)2-), simulated the measured U(VI) sorption data very well. The generalized composite surface complexation model, when compared to the constant or single-valued Kd model, more accurately predicted U(VI) sorption under the varying geochemical conditions expected at the IDF.     

Constituents isolated from Glehnia littoralis suppress proliferations of human cancer cells and MMP expression in HT1080 cells

Crude extract and solvent-partitioned fraction of Glehnia littoralis were found to possess different anti-proliferative effects against AGS, HT1080 and U937 human cancer cells. The crude extracts and solvent fractions dose-dependently inhibited cell proliferation. Especially, n-hexane and 85% aqueous MeOH fractions exhibited comparatively higher anti-proliferative effects and reduced expressions of Bcl-2, COX-2 and iNOS genes. Systematic separation of all solvent fractions by chromatographic methods led to the isolation of three glucopyranosides, four furanocoumarins and two polyacetylenic alcohols. All the nine compounds were evaluated for their inhibitory effects against both proliferation of human cancer cells and expressions of MMP-2 and -9 in HT1080 cells. Two polyacetylenic alcohols exerted the highest inhibitory activity against both human cancer cell lines, and MMP-2 and -9. These results suggest that G. littoralis may possibly be used as a valuable chemopreventive agent or food supplement for reducing cancer risk.     

Quality Characteristic and Shelf Life Studies of Deep-Fried Snack Prepared from Rice Brokens and Legumes By-Product

Legumes and cereal by-product flours were formulated into six of deep-fried snacks, which were evaluated for their physicochemical and sensory properties. Shelf life was analyzed for chemical parameters including: moisture gain, free fatty acid (FFA), and peroxide value (PV) at time intervals of 5 days along with organoleptic evaluation at the beginning and after 5, 10, 15, 20, 25, and 30 days of storage at room temperature (29 ± 2.0 °C) and relative humidity (67 ± 2.5%). A strong negative correlation (−0.83) was observed between the bulk density and the expansion ratio of the products. During storage moisture gain, FFA and PV increased linearly (R ² > 0.92). The results of organoleptic evaluation of all six fried snacks showed that there was no consistent pattern for sensory attributes. The maximum shelf life of the products was 24 days under the storage conditions studied.