Size dependence of the characteristics of Si single-electrontransistors on SIMOX substrates

A Si single-electron transistor (SET) was fabricated by converting a one-dimensional (1-D) Si wire on a SIMOX substrate into a small Si island with a tunneling barrier at each end by means of pattern-dependent oxidation. Since the size of the Si island became as small as around 10 nm owing to this novel technique, the total capacitance of the SET was reduced to a value of the order of 1 aF, which guaranteed the conductance oscillation of the SET even at room temperature. Furthermore, a linear relation between the designed wire length and the gate capacitance of SET's was obtained, which clearly indicates that the single island was actually formed in the middle of the one dimensional Si wire. These results were achieved owing to the highly reproducible fabrication process based on pattern dependent oxidation of SIMOX-Si layers     

A device analysis system based on laser scanning techniques

The organization of “A Device Analysis System Based on Laser Scanning Techniques” developed with the intention of measuring and analyzing the characteristics of the sample device, and the measured results with this system are presented.Since a sample-and-hold method for measurements of photoresponse current is employed, the dynamic (or static) photoresponse image can be obtained while the device under investigation is being operated in dynamic (or in static) and additionally, being checked on its functional operation with LSI evaluation unit. Images obtained are stored in digital image memories in real time and then processed with MPU in accordance with programs, in order to obtain the required information (ex. logic level of memory cell). And processed image(s) and laser reflected image superimposed on each other, are displayed on a color kinescope. As a result, even on dynamic type LSI such as dynamic MOS RAM, the logic levels of internal circuits could be successfully measured while in its dynamic operation, without contacting, in the atmospheric circumstance and moreover, in a nondestructive manner.In this report, measured results on a 4 K dynamic MOS RAM, CMOS shift register and a TTL logic IC are shown.This system is invaluable for the study of the operation of internal circuits not externally accessible and as an aid in testing with LSI tester and for failure analysis, at the stages of the design and the production.Besides, the resolution in depth could be improved by using an argon u.v. laser of shorter wavelength (λ = 351 nm, 364 nm) than HeNe laser (λ = 632.8 nm).     

A study of a fire on a diesel railcar

A fire broke out on a diesel railcar while running on a line of the Japan Railways Group. After an exhaustive investigation into the cause of the fire, it was found that the origin had been the lubricating oil of the engine. The lubricating oil vaporized from a long idling engine while the car was standing and accumulated in the exhaust silencer in considerable amounts. When the car was climbing up a long slope, the oil was exposed to a high-temperature exhaust gas and ignited. The flame attacked and melted the exhaust funnel, and eventually caused a fire.     

Calculations on endohedral C74 complexes

While empty C74 is still a rather elusive fullerene, its endohedral derivatives are well established. The report surveys computations for three of C74-based endohedrals--Ca@C74, Ba@C74, and Yb@C74. A set of six C74 cages is considered, namely one cage with isolated pentagons, three isomers with a pentagon-pentagon junction, two structures with one pair of connected pentagons, and one heptagon. Special interest is paid to the Gibbs-energy evaluations for estimations of the relative populations.     

Irradiation Resistance of Multicomponent Alloys

High-entropy alloys (HEAs) are characterized not only by high values of entropy but also by high atomic-level stresses originating from mixing of elements with different atomic sizes. Particle irradiation on solids produces atomic displacements and thermal spikes. The high atomic-level stresses in HEAs facilitate amorphization upon particle irradiation, followed by local melting and re-crystallization due to thermal spikes. We speculate that this process will leave much less defects in HEAs than in conventional alloys. For this reason, they may be excellent candidates as new nuclear materials. We discuss initial results of computer simulation on model binary alloys and an electron microscopy study on Zr-Hf-Nb alloys, which demonstrate extremely high irradiation resistance of these alloys against electron damage to support this speculation.     

Removal of hazardous phenols by microalgae under photoautotrophic conditions

Various algae were screened for their ability to decrease the concentration of 2,4-dinitrophenol (DNP), as a model compound of hazardous phenols, under photoautotrophic conditions. Chlorella fusca var. vacuolata and Anabaena variabilis grew well and showed high DNP removal ability over the concentration range of 5 to 40 microM. Their abilities to remove various phenols were investigated. More than 90% of 40 microM o- and m-nitrophenol and DNP was removed during the cultivation period of 5 d. o-, p-Chlorophenol and 2,4-dichlorophenol could be removed, but not to a significant extent. C. fusca also removed 85% of bisphenol A, suspected to be an endocrine disrupter. It was found that microalgae would be applicable to the removal of hazardous phenols without the addition of any organic carbon sources.     

Characteristic microstructure of curved human hair

Vol. 43 , No.3 (2009) pp.201–208 Hair appearance is affected by several factors, such as hair shape, color and optical properties relating to hair luster. For example, recently, we have found that meandering (curved) hair fibers increase with aging and cause the disordered alignment of hair fibers, resulting in a decrease in hair luster in older women. It is, therefore, important to understand the relationship between hair shape and its microstructure to control the fiber alignment and then the hair appearance. In this study, we have investigated the characteristic microstructure of curved human hair with microscopic methods and the following results were obtained: (i) The permeation behavior of fluorescein isothiocyanate into curved hair was asymmetrical. The permeation rate was faster from the convex‐side but slower from the concave‐side of the curved hair. This difference in permeation rate suggests structural and/or compositional differences between the convex‐ and concave‐sides. (ii) Transmission electron microscopic (TEM) observations revealed that macrofibril morphology is different between the convex‐ and concave‐sides. The macrofibrils in the convex‐side are relatively smaller and dispersed in inter‐macrofibrillar material, while those in the concave‐side are relatively larger and fused together. (iii) TEM observations also suggested that the alignment structure of intermediate filaments in the convex‐side is helical or twisted in each macrofibril, while that in the concave‐side is approximately parallel to the fiber axis. (iv) The amino acid analyses of the convex‐ and concave‐halves of the curved hair fibers revealed that Cys is lower and Asp, Glu and Gly are higher in the convex‐half. Interestingly, these results of the TEM observation and the amino acid analysis are analogous to the difference between ortho‐ and para‐cortical cells in wool fibers, suggesting the universal structure of curved mammalian hair.