Fatigue Growth Analysis of a Surface Crack in a Solid Cylinder under Combined Cyclic Axial-Torsion Loading

Experimental Techniques - In this paper, fatigue growth analyses of a surface crack in a solid cylinder under combined cyclic axial-torsion loadings through experimentation and numerical simulation...     

Effect of Sr loading on oxydehydrogenation of propane to propylene over Al2O3-supported V-Mo catalysts

Incorporation of strontium into V-Mo alumina-supported catalyst enhanced its performance (increased conversion and selectivity, decreased reducibility and improved stability) in propane oxydehydrogenation to propylene. 12.5% Sr loading was shown to be the optimum content to the V-Mo catalyst. The results were supported by various characterization techniques, namely, BET, XRD, SEM, FTIR and TPD.     

Opto-VLSI-based tunable photonic RF filter

In this paper, an Opto-Very-Large-Scale-Integrated (Opto-VLSI) based tunable photonic radio frequency (RF) filter structure is proposed and numerically simulated. The structure comprises a reconfigurable Opto-VLSI processor capable of arbitrarily steering optical beams of different wavelengths, a diffraction grating for wavelength division demultiplexing, and high-dispersion fibres for true-time delaying RF-modulated wavebands. The proposed structure has the ability to generate arbitrary wavebands and weights for realizing any RF filter responses. The proof-of-concept of the tunable photonic RF signal processor is also experimentally demonstrated by tuning its free-spectral range and altering its shape factor through optical beam steering.     

Site-directed mutagenesis study on the thermal stability of a chemiric PQQ glucose dehydrogenase and its structural interpretation

We have previously reported that a chimeric pyrroloquinoline quinone (PQQ) glucose dehydrogenase (GDH), E97A3, which was made up of 97% of Escherichia coli PQQGDH sequence and 3% of Acinetobacter calcoaceticus PQQGDH, showed increased thermal stability compared with both parental enzymes. Site-directed mutagenesis studies were carried out in order to investigate the role of amino-acid substitution at the C-terminal region, Ser 771, of a chimeric PQQGDHs on their thermal stability. A series of Ser 771 substitutions of a chimeric PQQGDH, E99A1, confirmed that hydrophobic interaction governs the thermal stability of the chimeric enzymes. Comparison of the thermal denaturation of E. coli PQQGDH and E97A3 followed by far-ultraviolet (UV) circular dichroism (CD) spectroscopy revealed that E97 A3 acquired stability at the first step of denaturation, which is reversible, and where no significant secondary structure change was observed. These results suggested that the interaction between C-terminal and N-terminal regions may play a crucial role in maintaining the overall structure of β-propeller proteins.     

Darstellung und strukturen diorganylsubstituierter Silicium-Germanium-Sauerstoff-achtringe

Diphenylgermanium diphenylsilicon oxide and dimethylgermanium diphenylsilicon oxide [(R₂Ge)O(Ph₂Si)O]₂ (R = Ph, Me) have been synthesized by treatment of diorganogermanium dihalides with diphenyldihydroxysilane. The X-ray analysis showed nonplanar eight-membered silicon-germanium-oxygen rings which are more puckered than those of cyclotetrasiloxanes. In the compound with R = phenyl the silicon and germanium atoms are disordered.     

Film analysis employing subtarget effect using 355 nm Nd-YAG laser-induced plasma at low pressure

The applicability of spectrochemical analysis for liquid and powder samples of minute amount in the form of thin film was investigated using ultraviolet Nd-YAG laser (355 nm) and low-pressure ambient air. A variety of organic samples such as commercial black ink usually used for stamp pad, ginseng extract, human blood, liquid milk and ginseng powder was prepared as film deposited on the surface of an appropriate hard substrate such as copper plate or glass slide. It was demonstrated that in all cases studied, good quality spectra were obtained with very low background and free from undesirable contamination by the substrate elements, featuring ppm or even sub-ppm sensitivity and worthy of application for quantitative analysis of organic samples. The proper preparation of the films was found to be crucial in achieving the high quality spectra. It was further shown that much inferior results were obtained when the atmospheric-pressure (101 kPa) operating condition of laser-induced breakdown spectroscopy or the fundamental wavelength of the Nd-YAG laser was employed due to the excessive or improper laser ablation process.     

Ruthenium-catalyzed selective synthesis of monoalkylated barbituric acids through “borrowing hydrogen” methodology

An environmentally benign alkylation of barbituric acids via “borrowing hydrogen” process with ruthenium catalysis has been established. The corresponding 5-(alkyl)barubituric acids were obtained in good to excellent yields with low catalyst loading. Various substrates including aliphatic alcohols were tolerated in the present catalytic system. A novel method for construction of barbituric acid-fused benzopyrane derivatives was also demonstrated.     

Effect of Sr loading on oxydehydrogenation of propane to propylene over Al₂O₃-supported V-Mo catalysts

Incorporation of strontium into V-Mo alumina-supported catalyst enhanced its performance (increased conversion and selectivity,decreased reducibility and improved stability) in propane oxydehydrogenation to propylene.12.5% Sr loading was shown to be the optimum content to the V-Mo catalyst.The results were supported by various characterization techniques,namely,BET,XRD,SEM,FTIR and TPD.