Esaki diodes live and learn

We report, as the result of shelf-life tests for Esaki diodes, the observation of minute but tangible reductions in the tunnel current after the lapse of half a century. The reduction could be attributed to 0.25% widening in the tunnel path.     

Competitive Trapping of Nitric Oxide (NO) Between Fe(III)-dithiocarbamate Complex and Liposome-encapsulated Trimethylammonio-PTIO: Effects of Ligand Structure, Charge on Liposome Surface, and External Pressure on NO-trapping Rates

Using a competitive nitric oxide (NO)-trapping method between Fe–dithiocarbamate (DTC) complexes and liposome-encapsulated 2-[4-trimethylammonio]-4,4,5,5-tetramethyl-imidazoline-1-oxyl 3-oxide (TMAPTIO), NO-trapping rates of Fe–DTC complexes in the presence of phosphatidylcholine liposomes were quantified for five kinds of Fe–DTC complexes. We investigated how the DTC ligand structure influences the NO-trapping rates of Fe–DTC complexes. The negatively charged liposomes give a higher NO-trapping rate of Fe–DTC complexes than do the positively charged ones, suggesting that the presence of a charge on the liposome surface affects the NO-trapping rate processes of Fe–DTC complexes. In addition, on the basis of the pressure dependence experiments for the competitive reaction, we evaluated the difference in activation volumes between the NO-trapping reactions by Fe–DTC complexes and TMA-PTIO, which allowed us to consider possible reaction mechanisms for the NO-trapping processes.     

Multitracer study on the effect of humate formation on the adsorption behavior of metal ions on kaolinite and silica gel

The multitracer technique was applied to elucidate of influence of humate formation on adsorption behavior of ultratrace elements. Dissolved fractions of Co, As, Rb, Sr, Y, Zr, Ba, Ce, Eu, Gd, Tb, Yb, Lu, Hf, Re and Pt in contact with kaolinite or silica gel were determined simultaneously either in the presence or absence of humic acid, which was partly adsorbed on the solid. Percentage of dissolved fraction of rare earth elements was identical to that of humic acid, indicating high stability of the rare earth-humate complex. Hydrolysis was the most important factor controlling the behavior of Zr and Hf. Both hydrolysis and humate complexation influenced the adsorption of Co, Sr, Ba and Pt, whereas neither affected the distribution of As, Rb and Re.     

Electron spin resonance spectra observed in the course of grafting iron carbonyls on sodium-Y zeolites

The adsorption and/or decomposition pathway of Fe₂(CO)₉ or Fe₃(CO)₁₂ on hydrated or dehydrated NaY zeolites has been studied by an ESR technique. The adsorption resulted in the formation of three paramagnetic species withg _iso=2.0450, 2.0378, and 2.0016, which were attributable to Fe₃(CO)₁₁ ^–, Fe₂(CO)₈ ^–, and Fe(CO)₄ ^– anion radicals, respectively. These radicals have been suggested as intermediates in the formation of HFe₃(CO)₁₁ ^– on the hydrated NaY zeolite and Fe₃(CO)₁₂ on the dehydrated NaY zeolite.     

Microscopic observation and characterization of the oil bridge between dehulled-roasted sesame seeds

The formation of an oil bridge between adhesive seeds was observed microscopically. The geometry of the oil bridge was affected by the shape of the adhesive seeds. The capillary force of the oil bridge was estimated from the image captured by the microscope. The average capillary force was 127 μN, which was five times higher than the average gravity of the seeds. It was observed that several oil bridges formed between two seeds. These results indicated an adequate ability of the seeds to adhere. The capillary force of the oil bridge increased with surface oil content. The probability of formation of an oil bridge increased with surface oil content when the surface oil content was above 0.63%. The probability of formation of an oil bridge markedly increased when sucrose was added to the seeds.     

Resonant photorefractive effect in InGaAs/GaAs multiple quantum wells

Semi-insulating InGaAs/GaAs multiple quantum wells are fabricated by metal-organic vapor-phase epitaxy and proton implantation. Two-wave mixing gain and four-wave mixing diffraction efficiency are measured at wavelengths of 0.91-0.94microm in the Franz-Keldysh geometry. We observe a large photorefractive effect caused by the excitonic electro-optic effect. The maximum diffraction efficiency reaches ~1.5x10(-4) .     

Remarkable effect of pore size on the catalytic activity of mesoporous silica for the acetalization of cyclohexanone with methanol

The catalytic activity of mesoporous silica (MCM-41) for the acetalization of cyclohexanone shows a volcano-shaped dependence on the pore diameter. The diameter of the cyclohexanone molecule is ca. 0.75 nm, while its acetalization with methanol was well accelerated on MCM-41 with a pore diameter of approximately 1.9 nm, and smaller or larger pores were not suitable for the catalysis. The catalytic activity was independent of the Al concentration.     

INHIBITORY EFFECTS OF ETHANOL ON THE PHOTODYNAMIC CELL INACTIVATION AND PETITE INDUCTION BY EUFLAVINE IN YEAST, Saccharomyces cerevisiae

Abstract— Effects of active oxygen scavengers on cell inactivation and petite induction of yeast by the photodynamic action of euflavine were examined. Histidine, sodium azide, 1,3-diphenyl-isobenzofuran and p-carotene, which are singlet oxygen scavengers, inhibited photodynamic cell killing. Histidine and sodium azide inhibited petite induction, too. These results suggested that photobiological effects of euflavine are induced via singlet oxygen-mediated Type II reaction process. In this work, however, we found that ethanol, which is reported to be a hydroxyl radical scavenger, notably inhibited photodynamic cell inactivation and petite induction by euflavine. Inhibition of petite induction was increased with increasing concentration of ethanol. Decrease of absorbance of euflavine by irradiation was also inhibited by the addition of ethanol.
These results suggested that ethanol possibly acts as a singlet oxygen scavenger.