Thermal destabilization of binary and complex metal hydrides by chemical reaction: A thermodynamic analysis

Some alkali and alkali-earth metal hydrides and their complex hydrides have very high hydrogen storage capacities and reversibility. Unfortunately, most of them have decomposition temperatures that are too high. This must be overcome before these hydrides can be considered seriously as practical hydrogen storage materials for on-board applications. In the present study, the CALPHAD approach has been adopted to evaluate thermodynamically the possibility of destabilizing these high temperature binary ionic hydrides and ternary complex hydrides by reacting them with light elements or other hydrides. The MgH₂+Si, LiBH₄+MgH₂, and LiBH₄+Al systems are predicted to show a significant decrease in decomposition temperature. On the other hand, the decrease in the decomposition temperatures of the MgH₂+Al and NaBH₄+Al systems is relatively small. The LiH+Si system also presents a considerable destabilization effect, which is consistent with experiment.     

The analysis of variance on process parameters affecting the microstructures of semi-solid Al-Zn-Mg alloy billet by cooling plate method

The cooling plate method is a simple and effective technique for preparing thixoforming feedstock. In this study, a feedstock with rosette-type structure was prepared by the cooling plate method. To determine the major factors and to ensure reproducibility via the cooling plate method for thixoforming billets statistically, the analysis of variance (ANOVA) technique and the Taguchi method were employed. The ANOVA was used to define the effect of each parameter, including the pouring temperature, the cooling plate angle, the holding time after pouring and the mold temperature. Among the factors analyzed, the pouring temperature had the most significant effect, particularly on the grain size. In addition, the plate angle and holding time were varied to reduce the effect of pouring temperature. The optimum conditions to achieve the desired microstructure using this method involved the use of a low pouring temperature (superheat (ΔT) value of less than 20 °C) and holding of the temperature of the cooling plate below the liquidus temperature. It was also found that the morphology of the grains quickly became globular when the billet was reheated to the liquid/solid temperature.     

Smilax China Root Extract Detoxifies Nicotine by Reducing Reactive Oxygen Species and Inducing CYP2A6

Resveratrol has a beneficial effect of lowering reactive oxygen species (ROS) and reduces cellular oxidative stress. We hypothesized that ethanol extract of Smilax china root (EESC) rich in resveratrol (RES) and oxyresveratrol (OXY) could reduce ROS caused by nicotine and promoting nicotine turnover by induction of CYP2A6. The amount of cotinine converted from nicotine was quantified by the direct barbiturate assay method. Expression of CYP2A6 was unregulated by RES, OXY, or EESC, respectively. Pretreatment of RES (50, 100, and 250 μM), OXY (50, 100, and 250 μM), and RES+OXY (50 and 100 μM) inhibited cytotoxicity and ROS production caused by nicotine in a dose‐dependent manner. EESC pretreatment (1.8 mg/mL) increased cell viability by 1.5‐fold higher than the control (nicotine only), and lowered cellular ROS levels. A significant amount of the conversion of nicotine to cotinine was observed in EESC pretreatment by CYP2A6 induction in HepG2 cells. These results suggested that hepatic induction of CYP2A6 and ROS reduction by EESC activate nicotine metabolism and reduce cellular oxidative stress.     

Frequency-Dependent Low Cycle Fatigue of Sn1Ag0.1Cu(In/Ni) Solder Joints Subjected to High-Frequency Loading

The low-cycle-fatigue characteristics of solder joints, formed by reflowing Sn98.8/Ag1.0/Cu0.1/In0.05/Ni0.02 solder over electroless nickel immersion gold-plated copper pads, were investigated by dynamic cyclic bending of printed circuit boards (PCBs). The PCB strain amplitudes were varied from 1.2 × 10^?3 to 2.4 × 10^?3 and the flexural frequencies ranged from 30 Hz to 150 Hz, to simulate drop impact-induced PCB resonant frequencies. A trend of drastically decreasing fatigue life with cyclic frequency was observed, in contrast with previous reports indicating the reverse; this is attributed to the different failure mechanisms activated. A systematic procedure involving optimization followed by transformation was used to condense the strain–frequency–life data into a master curve expressed in strain–life space.     

Factors generating boardings at Metro stations in the Seoul metropolitan area

This study is an investigation into the factors affecting Metro demand at a station level. These factors were examined in the Seoul metropolitan area, which is one of the most densely populated regions in the world. A regression analysis was conducted with weekly average of station boardings as the dependent variable. Twenty-four independent variables were chosen based on insights and findings from previous studies. They were categorized into three groups: built environment, external connectivity, and intermodal connection. Seven variables proved to be significantly associated with station boardings: employment, commercial floor area, office floor area, net population density, number of transfers, number of feeder bus lines, and a dummy variable indicating transfer stations. Furthermore, in order to identify indirect or cyclic relationships among variables in generating station boardings, which cannot be accounted for in regression analysis, a structural equation model (SEM) was adopted. Prior to the model identification, a conceptual framework was hypothesized. After testing a number of candidate SEMs within the framework, the final SEM was established. All links in the final model were statistically significant. Several links represented cyclic relationships between variables. As a result, some variables that were insignificant in the regression analysis were included in the final SEM. Variables in the external connectivity group were found to be associated with station boardings, and variables for land use and walkability proved to be indirectly related to station boardings through employment. In particular, the number of feeder bus lines was found to have a reciprocal relationship with station boardings. Several separate links represented a cyclic relationship between external connectivity and intermodal connection.     

Quantifying fenobucarb residue levels in beef muscles using liquid chromatography–tandem mass spectrometry and QuEChERS sample preparation

This paper describes a comparison of the properties of the three versions of the QuEChERS method (quick, easy, cheap, effective, rugged and safe) – the original (unbuffered), acetate-buffered, and citrate-buffered methods – for the determination of fenobucarb residues in beef muscles via liquid chromatography–electrospray ionisation tandem mass spectrometry (LC–ESI⁺-MS/MS). The recovery results were good for all the versions; however, the acetate-buffered version gave higher and more consistent recoveries for fenobucarb than the other versions. Performance characteristics, such as linearity, accuracy, and precision were determined. Matrix-matched standard calibration was used for quantification, obtaining recoveries in the range of 83.7–93.4% with relative standard deviations of <5%, at two spiking levels: 10 and 40 μg/kg. The limits of detection (LOD) and quantification (LOQ) were estimated to be 1.5 and 5 μg/kg, respectively. Finally, the method was applied to the analysis of 15 market samples, and no residues were found over the limit of quantification. The method developed was found able to determine the analyte with satisfactory intensity and accuracy.