High-resolution electron microscopy of nanocrystalline Ni-Al alloys: instability of ordered structure and dynamic behaviour of grain boundaries

High-resolution transmission electron microscopy was performed on vacuum-deposited nanocrystalline nickel aluminide films. Several nickel aluminide ordered structures, i.e. L1₂(Ni₃Al)-, B2(NiAl)-, D5₁₃(Ni₂Al₃)- and D0₂₀(NiAl₃)-type structures, were observed in the deposited films. The L1₂ and B2 ordered structures became unstable with decreasing grain sizes. The critical grain size on transformation from the L1₂- and B2-type ordered structures into disordered structures was ca. 5 nm at ambient temperatures. High atomic diffusion, sufficient for grain growth, and an increase in the ordering occurred just above 400°C in the nanocrystalline Ni-Al films with L1₂- and B2-type structures. The diffusion bonding process, at ambient temperatures, between Ni-Al nanocrystallites with an L1₂-type structure was observed dynamically at atomic resolution under strong electron irradiation. It was found that the nanocrystallites rotated and slid without crack generation, and neck-growth proceeded even at ambient temperatures.     

Characteristics of enhancement/depletion (E/D) gate MOSFET fabricated using ion implantation

The E/D gate MOSFET, which has an enhancement and depletion mode region under the same gate, is fabricated by using ion implantation as a tool for shifting threshold voltage. Threshold voltage, transconductance and drain breakdown voltage are studied as functions of implantation dose up to 12 × 10¹² cm^?2.It is found that, at an appropriate dose, the transconductance of this device is determined solely by the channel length of the enhancement mode region, and is larger than that of a short channel MOSFET with a standard structure but with the same drain breakdown voltage. Moreover, the dependence of threshold voltage on substrate bias measured in this device is found less sensitive to the transconductance than that in the standard short channel MOSFET.     

Spasmogenic and potentiating actions of some amino acids on the guinea-pig myometrium

Ectothiorhodospira shaposhnikovii, Chromatium minutissimum and Thiocapsa roseopersicina were grown in the dark under anaerobic conditions on media containing glucose or fructose and organic acids. Their cell contained the following enzymes of the fructose diphosphate pathway: phosphofructokinase, fructose diphosphate aldolase, and 3-phosphoglyceraldehyde dehydrogenase. The activity of fructose diphosphate aldolase was higher in the cells grown in the dark than in the cells grown in the light. The same enzymes of the tricarboxylic acid cycle were found in the cells cultivated in the dark on media containing organic acids as in the cells grown in the light, though the activity of some enzymes was lower. Only the activity of isocitrate lyase increased in the cells cultivated in the dark on a medium containing acetate.     

Manufacturing process and properties of nuclear RPV shell ring forged from hollow ingot

A shell ring for an RPV of a 1300 MWe type PWR was forged from a 200-ton hollow ingot, and its very high quality regarding the internal qualities, tensile properties, fracture toughness, fatigue properties and underclad cracking properties were confirmed. The steel was refined by a basic oxygen furnace and degassed by a vacuum treatment furnace.The manufacturing process of a large hollow ingot has been established by an improved core structure which enabled segregation of chemical components to be decreased and a clean inner surface to be obtained.     

New 1024-element charge-coupled linear image sensor with high sensitivity

A 1024-element charge-coupled linear image sensor with a new integration site array has been developed. The individual site consists of a photodiode and an m.o.s. capacitor. This arrangement results in high sensitivity and low dark-current signal.     

Measurements of the electron accumulation on two Schottky diodes connected metal to metal

Electron accumulation on the metal sides of two Schottky diodes connected metal to metal was observed as a result of the temporary variation of bias between the semiconductor sides of both diodes. The potential of the metals was found to be predictable by a theory based on a property of the Schottky diode.     

Ceramic capillary splices for optical fibres

A simple technique for splicing optical fibres is reported. The technique utilises a self-aligning ceramic capillary with inner dimensions slightly larger than the optical fibre. An average loss of below 0.1 dB is obtained for splices in graded-index and single-mode fibres with a 50 and 10 ?m core diameter, respectively.     

Isolation and analysis of age-related fluorescent substances in rat testes

Fluorescent substances were extracted from rat testicular tissue with 2,2-dimethoxypropane (DMP) and analyzed by 2-dimensional thin layer chromatography (TLC). One substance that accumulated with increasing age of the animals was isolated and analyzed quantitatively by spectrophotofluorometry using quinine sulfate as a standard. This substance, which was designated as an age-related fluorescent substance (ARFS), exhibited an excitation maximum at 355 nm and an emission maximum at 490 nm. Its fluorescence was quenched by metal chelators and at alkaline pH, indicating it contained a conjugated Schiff base structure. Quantitative analysis of this substance in the testes of rats 1, 2, 11 and 20 months of age showed that it increased linearly with age. The relation of this substance to aging also was indicated by its detection in animals of different ages fed diets of both low and high unsaturation.     

Solubility of BaS in BaO-BaF2 slag and the Influence of FeOx,SiO2, Cr2O3, BaCI2, CaO,and MgO on the sulfide capacity of this system

The influence of SiO₂, FeO_x, Cr₂O₃, BaCl₂, CaO, and MgO on the sulfide capacity of the BaO-BaF₂ system was measured at 1473 K, using a gas-slag-metal equilibration technique. It was found that the substitution of BaF₂ by SiO₂, FeO_x, Cr₂O₃, and BaCl₂ decreases the sulfide capacity of the BaO-BaF₂ system. Similar results were obtained for the carbonate capacity. The CaO-saturated BaO-BaF₂ flux, however, was found to have slightly higher sulfide and carbonate capacities than the pure BaO-BaF₂ flux. The solubility of CaO increased with increasing BaF₂ content and was 18 mol pet in BaF₂ at 1473 K. The solubility of MgO in the BaO-BaF₂ system at the same temperature is very low, and it has no effect on the sulfide and carbonate capacities. The solubility of BaS in the BaO-BaF₂ system was also measured at 1473 K and had its maximum for the slag containing 40 mass pet BaO. The activity of BaO in the system was calculated from those data. IVAN P. RACHEV, formerly Graduate Student, Department of Metallurgy, The University of Tokyo.