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To determine whether reactive oxygen species (ROS) play an essential role in hypoxic pulmonary vasoconstriction (HPV) and the cellular locus of ROS production and action during HPV, we measured internal diameter (ID) at constant transmural pressure, lucigenin-derived chemiluminescence (LDCL), and electron paramagnetic resonance (EPR) spin adduct spectra in small distal porcine pulmonary arteries, and dichlorofluorescein (DCF) fluorescence in myocytes isolated from these arteries. Hypoxia (4% [O.sub.2]) decreased ID, increased DCF fluorescence, tended to increase LDCL, and in some preparations produced EPR spectra consistent with hydroxyl and alkyl radicals. Superoxide dismutase (SOD, 150 U/ml) or SOD + catalase (CAT, 200 U/ml) did not alter ID during normoxia but reduced or abolished the constriction induced by hypoxia. SOD also blocked HPV in endothelium-denuded arteries after restoration of the response by exposure to [10.sup.-10] M endothelin-1. Confocal fluorescence microscopy demonstrated that labeled SOD and CAT entered pulmonary arterial myocytes. SOD, SOD + CAT, and CAT blocked the increase in DCF fluorescence induced by hypoxia, but SOD + CAT and CAT also caused a stable increase in fluorescence during normoxia, suggesting that CAT diminished efflux of DCF from cells or oxidized the dye directly. We conclude that HPV required increased concentrations of ROS produced by and acting on pulmonary arterial smooth muscle rather than endothelium. vascular smooth muscle; endothelium; electron paramagnetic resonance; dichlorofluorescein; lucigenin; superoxide dismutase; catalase

The generation and evolution of defects in 4H-SiC p-n junctions due to carrier injection under forward bias are investigated by synchrotron white beam x-ray topography, electroluminescence imaging, and KOH etching. Low angle grain boundaries are observed to act as one of a number of possible nucleation sites of stacking faults.

Adipocyte fatty-acid binding protein (A-FABP) plays a central role in many aspects of metabolic diseases. It is an important target in drug design for treatment of FABP-related diseases. In this study, molecular dynamics (MD) simulations followed by calculations of molecular mechanics generalized Born surface area (MM-GBSA) and principal components analysis (PCA) were implemented to decipher molecular mechanism correlating with binding of inhibitors 57Q, 57P and L96 to A-FABP. The results show that van der Waals interactions are the leading factors to control associations of 57Q, 57P, and L96 with A-FABP, which reveals an energetic basis for designing of clinically available inhibitors towards A-FABP. The information from PCA and cross-correlation analysis rationally unveils that inhibitor bindings affect conformational changes of A-FABP and change relative movements between residues. Decomposition of binding affinity into contributions of individual residues not only detects hot spots of inhibitor/A-FABP binding but also shows that polar interactions of the positively charged residue Arg126 with three inhibitors provide a significant contribution for stabilization of the inhibitor/A-FABP bindings. Furthermore, the binding strength of L96 to residues Ser55, Phe57 and Lys58 are stronger than that of inhibitors 57Q and 57P to these residues. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of NiMnSb films grown on InGaAs/InP(001) substrates by molecular-beam epitaxy are studied by X-ray diffraction, transmission electron microscopy (TEM), and ferromagnetic resonance techniques. X-ray diffraction and TEM studies showed that the NiMnSb films had the expected half-Heusler structure.

Abstract Diamond-like carbon (DLC) films were deposited on the nitrile butadiene rubber substrates by magnetron sputtering. The effects of the Ar sputtering pressure (SP) on the surface topography, structure, wettability and tribological performance of the DLC films were investigated. The DLC films' morphology as a function of SP was studied by atomic force microscopy, and their structural properties were investigated using Raman spectroscopy and FTIR. The Raman results revealed that a high SP contribute to forming sp3 bonds. The surface energy was calculated by the Owens-Wendt-Rabel-Kaelble method, and it peaked at a SP of 1.4 Pa. Tribological tests were performed using a ball-on-disc tribometry at a fixed load of 0.3 N under ambient conditions, which revealed that the tribological characteristics of DLC films can be tuned by varying the SP. The results showed that the DLC films prepared under 1.4 Pa SP exhibited enhanced triboperformance, based on a stable coefficient of friction lower than 0.25 during the whole test, which was very promising for practical tribological applications. [ABSTRACT FROM AUTHOR]

Abstract Diamond-like carbon (DLC) films were deposited on nitrile butadiene rubber (NBR) by the DC magnetron sputtering under different bias voltages. Raman spectra revealed that the variation of bias voltage could tune the carbon bond structure in DLC films. Both the hardness and Young's modulus increased with the increasing bias voltage. Tribological tests revealed that the DLC-coated NBR prepared at the bias voltage of −200 V exhibited low wear rate due to its high hardness. The sealing property was studied by evaluating the leakage rate of volatile liquid in a simple apparatus. All DLC films resulted in less leakage rate as compared to the raw rubber under large stress. The lowest leakage rate occurred in the DLC-coated NBR prepared with a bias voltage of −200 V, which was associated with the theoretical calculations (Persson's theory). It was attributed to the synergetic effects of the variations of the Young's modulus and root-mean-square (Rms) roughness. The low Young's modulus and Rms, controlled by regulating bias voltage, could enhance actual contact area and reduce the leakage rate. Highlights • Tribology property of diamond-like carbon film on rubber is tuned by bias voltage. • The coated diamond-like carbon film on rubber can impede the leakage. • Bias voltage can control the sealing property of coated nitrile butadiene rubber. [ABSTRACT FROM AUTHOR]

The transmission electron microscopy, atomic force microscopy, x-ray topography and KOH etching are used to investigate the nucleation of threading dislocations, both screw and edge-type, at the initial stages of silicon carbide (SiC) growth. The suppression of two-dimensional island nucleation by growth on off-cut seeds resulted in almost two orders by magnitude lower dislocation densities compared to crystals grown on on-axis seeds.

The 12 May 2008 Wenchuan earthquake in China triggered many rock avalanches that disrupted the transportation system and thereby caused additional fatalities. In this paper, several lines of evidence were forwarded to show that the rock avalanches, distributed along some highly destructed areas, i.e., the main seismic fault (F 2 ), had been enhanced by natural explosions and fires immediately after the main earthquake. Burned rock samples from the explosion pits near the highly destructed parts of Shuijingyan (SJY), north of Beichuan County, were collected and analyzed in the laboratory. The brown porous ejecta were featured by intensive thermophili degradation because they had high content of polycyclic aromatic hydrocarbons. Microstructure and composition analyses indicated that four samples, a mixture of reef limestone and manganese ore, were carbonate manganese and carbonaceous rock, which generally is buried at 500–2000 m depth. With high content of polycyclic aromatic hydrocarbons, the brown porous ejecta were believed to have reached a highly thermal degradation process compared with surrounding and intact counterpart rocks. [ABSTRACT FROM AUTHOR]