Phase relationship on Mo-S system at high temperatures

Changing the partial pressure of sulfur Ps₂ at temperatures of 750° and 950°C, phase equilibria on the Mo-S system by solid-gas reaction were investigated. Hexagonal 2H-MoS₂ and monoclinic Mo₂S₃ phases were identified from the x-ray powder diffraction pattern. The 2H-MoS₂ had a slight homogeneity range, i.e. MoS_1.978 to MoS_2.0 at 950°C, MoS_1.983 to MoS_2.0 at 750°C. No remarkable variation of lattice parameters for the MoS₂ was observed. The composition of the Mo₂S₃ phase was not stoichiometric MoS_1.5 but MoS_1.457 at 950°C. At 750°C the composition of the Mo₂S₃ phase could not be determined since it was quite difficult to establish the equilibrium state between the gas and the condensed phases. This finding agreed well with the result of Morimoto and Kullerud.     

Spectral interferometric microscope with tandem liquid-crystal Fabry-Perot interferometers for extension of the dynamic range in three-dimensional step-height measurement

The maximum measurable range of a spectral interference microscope depends on the coherence length of the light transmitted by its tunable spectral filter. To achieve a large range in step-height measurement we have developed a new tunable spectral filter that uses tandem liquid-crystal Fabry-Perot interferometers (LC-FPIs), which can simultaneously attain both a high spectral resolution and a large tuning range. Fringe visibility measurements were carried out, and it was found that the coherence length of the light transmitted through tandem LC-FPIs is two times larger than that transmitted through a single LC-FPI. Using this novel tunable spectral filter, we developed a new spectral interference microscope for the measurement of three-dimensional shapes of discontinuous objects. Experimental results of step-height measurements both with a single LC-FPI and with tandem LC-FPIs are presented for a combination of standard steel gauge block sets with 1-, 99-, and 100-microm steps. A large range (1-100 microm) of measurement with submicrometer resolution was achieved with tandem LC-FPIs that was not possible with our previous system in which a single LC-FPI was used.     

Hypomagnesemia as a predictor of mortality in hemodialysis patients and the role of proton pump inhibitors: A cross‐sectional, 1‐year,retrospective cohort study

Introduction This study aimed to evaluate the association between proton pump inhibitor (PPI) use and serum magnesium levels, and the role of hypomagnesemia and PPI use as a risk factor for mortality in hemodialysis patients. Methods An observational study, including a cross‐sectional and 1‐year retrospective cohort study. The study comprised 399 hemodialysis patients at a single center, and was conducted from January to September 2014. Multiple linear regression analysis was used to investigate the independent relationship between serum magnesium levels and baseline demographic and clinical variables, including PPI and histamine‐2 receptor antagonist use. Cox regression model was used to identify lower serum magnesium level and PPI as a predictor of 1‐year mortality. Findings Serum magnesium levels were lower with PPI use than non‐PPI use (2.39 ± 0.36 vs. 2.56 ± 0.39 mg/dL, P < 0.001). Multiple linear regression analysis showed that PPI use, low serum albumin levels, and low serum potassium and high‐sensitivity C‐reactive protein (hs‐CRP) levels were significantly associated with low serum magnesium levels. A total of 29 deaths occurred during the follow‐up period. According to Cox regression analysis stratified by hs‐CRP, only high serum hs‐CRP levels (>4.04 mg/L) in association with low serum magnesium levels was an independent risk factor for 1‐year mortality (hazard ratio: 2.92; 95% CI: 1.53–6.40, P < 0.001). Discussion Serum magnesium levels are lower in PPI use. In the inflammatory state, a low serum magnesium level is a significant predictor of mortality in hemodialysis patients.     

Photoconductivity of DLC film deposited by pulsed discharge plasma CVD

DLC films were deposited by a new pulsed DC discharge plasma chemical vapour deposition (CVD) using hydrogen and methane gas mixture. When methane concentration (Cm) i.e. CH₄/(H₂ + CH₄) was increased from 3 to 40%, the graphitization of the carbon film increases as evident from Raman study. When Cm was increased to 30%, DLC film shows photoconducting property. The white light photoconductivity (S = I_l/I_d, where I_l is light current and I_d is dark current) measured with solar simulator under AM 1.5 condition was approximately 20 at room temperature. The photoconductivity was not clear when Cm was lower than 20%. ESR measurements also show that the electron spin density was slightly decreased with decreasing concentration of methane. Thus we can conclude here that at higher concentrations of methane at 30%, Sp² content of the film increases and the DLC film becomes photoconducting.     

DC interruption characteristic of vacuum circuit breaker

A high‐speed vacuum circuit breaker (HSVCB) has been investigated. HSVCB makes high‐frequency current superimposed on a fault current so that the current is forced to be zero and is interrupted. Its interruption performance is considered to be dependent on the rate of change of the current (di/dt). As a fundamental research, we investigated the di/dt– dv/dt characteristics and the insulation recovery characteristic after interrupting the counter‐pulse current for various contact materials of AgWC, CuW, and CuCr. The results revealed that the case where the gap length is larger is better in a current interruption performance. Moreover, it was found that di/dt is not dependent on the insulation recovery characteristics, but the magnitude of interruption current is of great influence. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(1): 17– 25, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20362     

EFFECTS OF HEXASULFOBUTYLATED C60 ON THE GASTRIC CIRCULAR MUSCLE OF GUINEA PIG

The effects of hexasulfobutylated (FC₄S), the fullerene derivative on the contraction of smooth muscle were tested pharmacologically on the circular muscle of stomach of guinea pigs. The effects of monomalonic acid C₆₀ (MMA C₆₀) on the same preparations were compared. The effects of those compounds on the taenia coli, portal vein and vas deferens of guinea pigs were also tested. The FC₄S did, while MMA C₆₀ did not elicit contracture of the circular muscle of stomach and taenia coli. Both FC₄S and MMA C₆₀ did not elicit contraction on the portal vein and on the vas deferens of the guinea pig. Prazosin (0.5 μM) or propranolol (0.5 μM) did not alter the FC₄S elicit contracture of the circular muscle of stomach. However, atropine (0.01, 0.1 and 1 μM), tetrodotoxin (0.1 μM) or low calcium medium decreased reversibly the FC₄S elicited contracture of the circular muscle of stomach. The effect of FC₄S on the contracture of the gastric muscles was also tested using various muscarinic receptor subtype antagonists. 4-DAMP (1 μM), muscarinic M3 receptor antagonist, and tropicamide (1 μM), muscarinic M4 receptor antagonist, did not alter the contracture elicited by FC₄S. Pirenzepine (0.1 μM), muscarinic M1 receptor antagonist, and methoctramine (0.25 μM), muscarinic M2 receptor antagonist, significantly decreased the FC₄S elicited contracture of the circular muscle. Atropine (1 μM) or tetrodotoxin (0.1 μM) completely blocked the FC₄S elicited contracture of the circular muscle of stomach. It is concluded that FC₄S elicited contracture of the circular muscle of stomach. The effect may be due to FC₄S acts on the cholinergic cells existed in the gastric muscle and indirectly activating the tetrodotoxin dependent releasing of the transmitters from the cells, then, activating the muscarinice M1, M2 receptors in the muscle eliciting the contractures.     

GaN-based optoelectronic devices on sapphire and Si substrates

A recessed gate AlGaN/GaN high-electron mobility transistor (HEMT) on sapphire (0 0 0 1), a GaN metal-semiconductor field-effect transistor (MESFET) and an InGaN multiple-quantum well green light-emitting diode (LED) on Si (1 1 1) substrates have been grown by metalorganic chemical vapor deposition. The AlGaN/GaN intermediate layers have been used for the growth of GaN MESFET and LED on Si substrates. A two-dimensional electron gas mobility as high as 9260 cm²/V s with a sheet carrier density of 4.8×10¹² cm⁻² was measured at 4.6 K for the AlGaN/GaN heterostructure on the sapphire substrate. The recessed gate device on sapphire showed a maximum extrinsic transconductance of 146 mS/mm and a drain–source current of 900 mA/mm for the AlGaN/GaN HEMT with a gate length of 2.1 μm at 25°C. The GaN MESFET on Si showed a maximum extrinsic transconductance of 25 mS/mm and a drain–source current of 169 mA/mm with a complete pinch-off for the 2.5-μm-gate length. The LED on Si exhibited an operating voltage of 18 V, a series resistance of 300 Ω, an optical output power of 10 μW and a peak emission wavelength of 505 nm with a full-width at half-maximum of 33 nm at 20 mA drive current.     

Proton-conducting electrolyte membranes based on hyperbranched polymer with a sulfonic acid group for high-temperature fuel cells

The hyperbranched polymers (HBP-SA-Acs) with both a sulfonic acid group as a functional group and an acryloyl group as a cross-linker at terminals in different ratios of sulfonic acid group/acryloyl group (SO₃H/Ac) were successfully synthesized as a new thermally stable proton-conducting electrolyte. The cross-linked hyperbranched polymer electrolyte membranes (CL-HBP-SAs) were prepared by thermal polymerizations of the HBP-SA-Acs using benzoyl peroxide, and their ionic conductivities under dry condition and thermal properties were investigated. The ionic conductivities of the CL-HBP-SAs were found to be in the range of 2.2 × 10⁻⁴ to 3.3 × 10⁻⁶ S/cm, depending upon the SO₃H unit contents, at 150 °C under dry condition, and showed the Vogel-Tamman-Fulcher (VTF) type temperature dependence, indicating that proton transfer is cooperated by local polymer chain motion. All CL-HBP-SAs were thermally stable up to 260 °C, and they had suitable thermal stability as electrolyte membranes for the high-temperature fuel cells under dry condition. Fuel cell measurement using a single membrane electrode assembly cell with a cross-linked electrolyte membrane was successfully performed under non-humidified condition. It was demonstrated that applying the concept of dry polymer system to proton conduction is one possible approach toward high-temperature fuel cells.     

Proposal of limit moment equation applicable to planar/non-planar flaw in wall thinned pipes under bending

In this paper, a limit bending moment equation applicable to all types of planar and non-planar flaws in wall-thinned straight pipes under bending was proposed. A system to rationally classify the planar/non-planar flaws in wall-thinned pipes was suggested based on experimental observations focused on the fracture mode. The results demonstrate the importance of distinguishing between axial and circumferential long flaws in wall-thinned pipes.     

Determination of optical purity and absolute configuration of natural 12‐hydroxystearic acid by the 1H NMR anisotropy method

The enantiopure of (R)‐(?) MαNPA was allowed to react with racemic 18‐(tert‐butyldimethylsilyloxy)‐5‐octadecayne‐7‐ol which was derived from dodecane‐1,12‐diol, yielding diastereomeric esters mixture. These racemic esters were easily separated by HPLC on silica‐gel. The absolute configurations of the first‐eluted diastereomeric esters from the separated esters were determined using ¹H NMR anisotropy method. Analysis on ¹H NMR spectra and HPLC elution time of the synthesized esters and those of MαNP ester derived from natural methyl‐12‐hydroxystealate showed that the absolute configuration of natural 12‐hydroxystearic acid was R form, and the enantiomeric excess was over 99%.