Resistive superconducting transition of κ-type BEDT-TTF organic superconductors in a magnetic field

The superconducting transition of the organic compoundsκ-(BEDT-TTF)₂ X is studied by resistive measurement in a magnetic field up to 10 T applied normal to the conducting plane. For the salts withX=Cu[N(CN)₂]Br andX=CuCN[N(CN)₂] the transition shows fanshaped broadening caused by superconductivity fluctuation. For theX=Cu(NCS)₂ salt the resistivity shows a peak in the transition region in a magnetic field below 4 T.This phenomenon is suppressed in defect-reduced samples for intralayer conduction. We discuss this peak in relation to the thermal fluctuation on the Josephson junction structures in this salt.     

Plastic deformation of bcc metal thin foils without dislocation

Heavy plastic deformation of fcc metal thin foils to fracture has been found recently to proceed without involving dislocations, and it results in the formation of high density of vacancy clusters. Thin foil specimens of bcc metals such as V and Mo were plastically deformed to fracture in in situ elongation experiments under an electron microscope. Morphology of thinning and fracture was found to be similar to fcc metals, and no dislocation was observed during heavy deformation. Electron diffraction analysis at the tip of a crack during deformation confirmed a large elastic deformation of up to 5%. Unlike in fcc metal thin foil specimens, point defect clusters were not observed near fractured tips. This difference is attributed to the difference in vacancy reaction, though the deformation in bcc metals without dislocation most likely does produce vacancies.     

Ethanol production from raw starch by a recombinant yeast having saccharification and fermentation activities

In order to develop a method for converting raw starch into ethanol efficiently, direct fermentation of ozonized raw starch using a recombinant yeast was investigated. Ozonolysis was carried out as a pretreatment to convert raw starch into ethanol rapidly and efficiently, and then the effect of the ozone degradation conditions on the degree of polymerization and the amount of amylose in a raw starch was determined. Since the degree of polymerization was low and the amount of amylose was high, raw starch treated with an ozone concentration of 40 gm^?3 and an ozonation time of 30 min was the material chosen for alcohol fermentation. Though the recombinant yeast could not convert the untreated raw starch, it converted the soluble starch and the ozonized raw starch at a comparatively high yield into ethanol. About 56% of the ozonized raw starch decomposed, and the ethanol concentration obtained from the ozonized raw starch was markedly greater than that obtained from untreated raw starch. The dynamic behavior of cell growth, substrate degradation, and ethanol production was examined in a continuous culture under various dilution rates, and the optimal dilution rate, ie 0.15 h^?1, was determined for maximizing the ethanol productivity (amount of ethanol produced per unit time). © 2002 Society of Chemical Industry     

Efficient usage of highly dispersed Pt on carbon nanotubes for electrode catalysts of polymer electrolyte fuel cells

A Pt-deposited carbon nanotube (CNT) shows higher performance than a commercial Pt-deposited carbon black (CB) with reducing 60% Pt load per electrode area in polymer electrolyte fuel cells (PEFCs) below 500 mA/cm². K₂PtCl₄ and H₂PtCl₆·6(H₂O) are used for the Pt deposition onto multi-walled CNTs (MWCNTs), which are produced by the catalytic decomposition of hydrocarbons. The electric power densities produced using the Pt/CNT electrodes are greater than that of the Pt/CB by a factor of two to four on the basis of the Pt load per power. CNTs are thus found to be a good support of Pt particles for PEFC electrodes. TEM images show 2–4-nm Pt nanoparticles dispersed on the CNT surfaces. These high performances are considered to be due to the efficient formation of the triple-phase boundaries of gas–electrode–electrolyte. The mechanisms of Pt deposition are discussed for these Pt-deposited CNTs.     

Corrosion of silicon nitride ceramics under hydrothermal conditions

Corrosion behaviour of Si₃N₄ ceramics containing Y₂O₃, Al₂O₃ and AIN as sintering aids was investigated under hydrothermal conditions at 200–300 C and saturated vapour pressures of water for 1–10 days. Hydrothermal corrosion resulted in the dissolution of the Si₃N₄ matrix and the formation of a product layer consisting of the original grain-boundary phases and hydrated silica. The dissolution rate of Si₃N₄ ceramics decreased with decreasing crystallinity of the grain-boundary phase. The dissolution rate could be adequately described by a parabolic plot in the initial stage of the reaction. The apparent activation energies were 83.5–108 kJ mol^–1, and the bending strength of the corroded samples decreased from 600 to 400 MPa in the initial stage of the reaction upto a weight loss of 0.004 g cm^–2, and then was almost constant up to a weight loss of 0.012 g cm^–2.     

Analytical study on cantilever resonance type magnet-integrated sensor device for micro-magnetic field detection

A beam-shaped cantilever resonance type magnetic sensor device has been proposed with a micro magnet. Two structural designs, named as design 1 and design 2, have been comparatively analyzed using ANSYS in order to obtain larger frequency shifts (higher magnetism sensitivity) due to the applied exterior magnetic field. The analytical results show that, in the range of 0–10 mT, the frequency shifts are small, while under 100 mT, a relatively larger frequency shift of about 30 Hz can be theoretically obtained. The power consumption of the proposed devices has been further theoretically studied for preliminary understanding. Using the well-known displacement equations, the estimated power consumption is around 0.21 μW, which is very lower than that of the reported magnetic field sensors. This implies that it is possible to fabricate higher sensitive magnetic field sensor with lower power consumption.     

Hierarchical learning from human preferences and curiosity

Applied Intelligence - Recent success in scaling deep reinforcement algorithms (DRL) to complex problems has been driven by well-designed extrinsic rewards, which limits their applicability to many...     

A new water-resistant snow index for the detection and mapping of snow cover on a global scale

An up-to-date spatio-temporal change analysis of global snow cover is essential for better understanding of climate–hydrological interactions. The normalized difference snow index (NDSI) is a widely used algorithm for the detection and estimation of snow cover. However, NDSI cannot discriminate between snow cover and water bodies without use of an external water mask. A stand-alone methodology for robust detection and mapping of global snow cover is presented by avoiding external dependency on the water mask. A new spectral index called water-resistant snow index (WSI) with the capability of exhibiting significant contrast between snow cover and other cover types, including water bodies, was developed. WSI uses the normalized difference between the value and hue obtained by transforming red, green, and blue, (RGB) colour composite images comprising red, green, and near-infrared bands into a hue, saturation, and value (HSV) colour model. The superiority of WSI over NDSI is confirmed by case studies conducted in major snow regions globally. Snow cover was mapped by considering monthly variation in snow cover and availability of satellite data at the global scale. A snow cover map for the year 2013 was produced at the global scale by applying the random walker algorithm in the WSI image supported by the reference data collected from permanent snow-covered and non-snow-covered areas. The resultant snow-cover map was compared to snow cover estimated by existing maps: MODIS Land Cover Type Product (MCD12Q1 v5.1, 2012), Global Land Cover by National Mapping Organizations (GLCNMO v2.0, 2008), and European Space Agency’s GlobCover 2009. A significant variation in snow cover as estimated by different maps was noted, and was was attributed to methodological differences rather than annual variation in snow cover. The resultant map was also validated with reference data, with 89.46% overall accuracy obtained. The WSI proposed in the research is expected to be suitable for seasonal and annual change analysis of global snow cover.