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Solid solutions of GaN in ZnO (Zn1-zGaz)(O 1-xNx) (x and z le; 0.15) have been prepared by simple solution combustion method. Except for minor changes in the lattice contraction, no significant change in the Wurtzite structure was observed. Raman and secondary ion mass spectrometry results show the direct Zn - N and Ga - N bonds in (Znl-zGaz)(Ol-xNx). Visible light absorption and XPS results demonstrate that N 2p states of nitride occupy the states above the O 2p valence band, and hence a change in optical band gap reduction occurs to ?2.5 eV from 3.37 eV for ZnO. Significant nitrogen fixation catalytic activity through NH3 formation has been observed at ambient pressure on virgin (Znl-zGaz)(O l-xNx) material, indicating its potential as a catalyst. � 2009 American Chemical Society.

The adsorption of oleic acid / oleate on fluorite surface could be visualized using tapping mode of atomic force microscopy (AFM). The natural fluorite crystals were equilibrated with 10 − 3 to 10 − 7 M oleate solutions and their AFM images at each concentration along with height profiles were recorded. Even at low oleate concentration of 1 × 10 − 7 M, concomitant monolayer and bilayer structures were observed. It suggests that normal–normal bonding of hydrocarbon chains takes place before the surface is completely covered by the monolayer. Multi-layer adsorption of oleate was observed at oleate concentrations of above 10 − 4 M. The tapping mode AFM can be utilized to visualize the topography of surfaces adsorbed with surfactant molecules.

Hepatic stellate cells are liver-specific pericytes and exist in close proximity with endothelial cells. The activation of liver pericytes is intrinsic to liver pathogenesis, and leads to endothelial dysfunction, including the low bioavailability of nitric oxide (NO). However, the role of nitric oxide in pericyte–endothelium cross-talk has not yet been elucidated. This work examines the cellular mechanism of action of NO in pericyte-mediated endothelial dysfunction. We used in vitro coculture and conditioned medium systems to study the effects of activated liver pericytes on endothelial function, and an egg yolk vascular bed model was used to study the effects of activated pericytes on angiogenesis. This study also demonstrates that activated pericytes attenuate the migration, proliferation, permeability, and NO production of endothelial cells. Our results demonstrate that activated pericytes restrict angiogenesis in egg yolk vascular bed models, and NO supplementation recovers 70% of the inhibition. Our results also demonstrate that supplementation with NO, sildenafil citrate (phosphodiesterase inhibitor), and 8-bromo-cGMP (cGMP analog) partially recovers activated-pericyte-mediated endothelium dysfunction. We conclude that NO–cGMP alleviates activated-pericyte-associated endothelial dysfunction, including angiogenesis, in a cGMP-dependent manner.

Dimethyl carbonate synthesis with 80 mol% yield is achieved through transesterification of ethylene carbonate with methanol at ambient conditions (RT and atmospheric pressure) using alkali and alkaline-earth tungstates as solid catalysts. The catalysts are efficient even at the sub-ambient temperatures. Reactions under CO2 pressure indicate that CO2 atmosphere retards the transesterification reaction completely below 100 °C. Experimental conditions of 150 °C and 3.4 MPa CO2 pressure are required to obtain maximum DMC yield of 71 mol%. Synthesis of DMC by one-pot synthesis using epoxide, CO2 and methanol is not as effective as that by two-step method with the present catalyst system. Raman and IR spectra of methanol-interacting tungstates indicate the formation of a methoxide ion species adsorbed at the catalyst surface as one possible reaction intermediates.

Commercial synthetic polymers namely Polycarbonate (PC), Low density polyethylene (LDPE), High density polyethylene (HDPE), and Polypropylene (PP) coupons were immersed for a period of 12 months (Feb 2006 - Feb 2007) in Bay of Bengal, East coast, India. Samples were retrieved every month and the extent of biofouling and biodegradation were monitored. Biofouling was found to depend not only on the season but also on the chemical nature of the polymer. Surface energy of all the four polymers is positively correlated with fouling only at the initial stages (three months) while surface roughness had a negative correlation. The later increased during the study period. Total suspended solids and organic matter were more abundant on HDPE, followed by PP and LDPE, indicating that among polyolefins hydrophobic surfaces (lower surface energy) favor biofouling over one year. Maximum fouling was observed on polycarbonate during initial three months. Chlorophyll a showed a decreasing trend during the study, as secondary foulers such as Balanus amphitrite, were dominant after the monsoon (6th month in the present study). Maximum weight loss was seen in LDPE (1.9%), followed by that in HDPE (1.6%), PC (0.69%) and finally in PP (0.65%) samples in the 12 months time period. FTIR spectra of PC displayed a decrease in carbonate carbonyl index, while an initial increase and a decrease in carbonyl index of polyolefins as a function of time indicated biodegradation. � 2009 Elsevier Ltd. All rights reserved.

We have measured the permeability of rhodamine-6G across Cx43 hemichannels reconstituted on a pipette tip. Cx43 hemichannels were overexpressed in Sf9 cells, and affinity-purified. The hemichannels were reconstituted in a lipid bilayer on a pipette tip by the tip-dip method. R6G in the pipette permeated across the channels into the bath. The permeability of R6G was quantified by measuring R6G concentration in the bath after several hours by surface enhanced Raman spectroscopy (SERS) with 100 nm silver colloid particles. The ratio of the permeability of dye to salt, as extracted by this combined electrical-SERS technique, is compatible with similar ratios for other dyes across whole gap junction channels. The results for the permeability ratio were further compared to fluorescence measurements. The novel combination of patch and SERS techniques can be extended to quantifying the transport of biologically significant non-fluorescent molecules, such as cAMP and IP3, across 1 nm sized pores, such as the gap junction channel.