In-situ monitoring of the stabilization with hydrogen of free radicals thermally induced from coal using high pressure e.s.r., d.t.a. and p.d.a. equipment

High temperature, high pressure e.s.r. measurements of the hydrogenation reaction of Taiheiyo coal in the presence of catalysts were carried out to understand the stabilization of thermally and/or catalytically induced free radicals. A decrease in free radical concentration with increasing temperature was observed for ZnCl₂ and SnCl₂ · 2H₂O catalysts at 10MPa under hydrogen gas. High pressure modified single-cell d.t.a. and p.d.a. equipment augmented the uniquely designed high temperature, high pressure e.s.r. cell. The hydrogenation reaction was monitored under the same experimental conditions as for e.s.r. From the results of the combination of high temperature, high pressure e.s.r. with high pressure d.t.a. and p.d.a., it was established that H₂ molecules can react efficiently with free radicals from coal molecules created by the presence of ZnCl₂ and SnCl₂ · 2H₂O catalysts.     

Comparisons of computed mobile phone induced SAR in the SAM phantom to that in anatomically correct models of the human head

The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, Sub-Committee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position.     

Computer aided-molecular design of high performance nano-carbon materials: Na on graphenes

The electronic states of sodium ion (Na⁺) trapped on the model surfaces of amorphous carbon have been investigated by means of hybrid density functional theory (DFT) calculations to elucidate the nature of interaction between Na⁺/Na and the amorphous carbon surfaces. Also, direct molecular orbital-molecular dynamics (MO-MD) calculation [Tachikawa and Shimizu, J. Phys. Chem. B, 110 (2006) 20445] was applied to diffusion processes of the Na⁺ ion on the model surface of amorphous carbon. Seven models of graphene sheets (n = 7, 14, 19, 29, 37, 44 and 52, where n means numbers of rings in each carbon cluster) were considered in the present study. The B3LYP/LANL2MB calculations showed that the sodium ion is located at 2.24-2.26 Å from the graphene surfaces. The direct MO-MD calculations showed that the Na⁺ ion diffuses freely on the surface above 300 K. At higher temperature (1100 K), the Na⁺ ion moved from the center to edge region of the model surface. The nature of the interaction between Na⁺ and the amorphous carbon surfaces was discussed on the basis of theoretical results.     

Numerical shape identification of cavity in three dimensions based on thermal non-destructive testing data

Shape identification analysis is carried out to obtain hitherto unknown defect shapes in a structure, based on the finite element and the adjoint variable methods. In this study, a test piece incorporating a known defect shape was employed to solve the shape identification problem. Also reported in this study is the shape identification problem of a cavity in a heated resin test piece made using a 3D printer by employing the temperature pattern observed on the surface of the test piece. The surface temperature of a test piece will not be uniformly distributed if it contains cavities. Practical experiments have confirmed that the characteristic of the temperature distribution depends on the size of the cavity. The thermal physical constants, i.e. the thermal conductivity and the convection coefficient, were identified for a model of the test piece incorporating a cavity based on the experimental data. Shape identification analysis was then carried out. Using numerical analysis, the finite element method was applied to simulate the temperature distribution in the test piece, and the adjoint variable method was employed to identify the cavity's shape.     

Differential expression of alpha 1(IV), alpha 2(IV), alpha 5(IV) and alpha 6(IV) collagen chains in the basement membrane of basal cell carcinoma

Type IV collagen, the major component of basement membrane, consists primarily of alpha 1(IV) and alpha 2(IV) chains. Recently, other types of collagen IV chains, i.e. alpha 3(IV), alpha 4(IV), alpha 5(IV) and alpha 6(IV) chains, have been identified by protein chemistry and molecular cloning. We have examined the diversity of the assembly of alpha (IV) chains of the basement membrane surrounding tumour nests of basal cell carcinomas, in tissues from 11 patients, by immunohistochemical analysis using specific monoclonal antibodies to six alpha (IV) chain. The immunostaining profile of each chain differed with respect to the histological subtypes of basal cell carcinoma. In the morphea-like subtype, which was more invasive, alpha 1(IV) and alpha 2(IV) chains were discontinuously stained, and alpha 5(IV) and alpha 6(IV) chains were entirely absent. However, in the superficial subtype, which was non-aggressive, alpha 1(IV), alpha 2(IV), alpha 5(IV) and alpha 6(IV) chains were well stained compared with the other subtypes of basal cell carcinoma. In addition, in the solid subtype, which showed slow growth and ulceration, alpha 1(IV) and alpha 2(IV) chains were continuously stained, and alpha 5(IV) and alpha 6(IV) chains were discontinuous or absent. The assembly of alpha 5(IV) and alpha 6(IV) chains into the basement membrane was inhibited in the solid and morphea subtypes of BCC. This differential expression of type IV collagen chains seems to be associated with the invasive potential of basal cell carcinoma.     

A 16-ns 1-Mb CMOS EPROM

A 16-ns 1-Mb CMOS EPROM has been developed utilizing high-speed circuit technology and a double-metal process. In order to achieve the fast access time, a differential sensing scheme with address transition detection (ATD) is used. A double-word-line structure is used to reduce word-line delay. High noise immunity is obtained by a bit-line bias circuit and data-latch circuit. Sufficient threshold voltage shift (indispensable for fast access time) is guaranteed by a threshold monitoring program (TMP) scheme. The array is organized as 64 K×16 b, which is suitable for 32-b high-performance microprocessors. The active power is 425 mW, the programming time is 100 μs, and the chip size is 4.94×15.64 mm²     

A 62-ns 16-Mb CMOS EPROM with voltage stress relaxation technique

To meet the increasing demand for higher-density and faster EPROMs, a 16-Mb CMOS EPROM has been developed based on 0.6-μm N-well CMOS technology. In scaled EPROMs, it is important to guarantee device reliability under high-voltage operation during programming. By employing internal programming-voltage reduction and new stress relaxation circuits, it is possible to keep an external programming voltage V_pp of 12.5 V. The device achieves a 62-ns access time with a 12-mA operating current. A sense-line equalization and data-out latching scheme, made possible by address transition detection (ATD), and a bit-line bias circuit with two types of depletion load led to the fast access time with high noise immunity. This 16-Mb EPROM has pin compatibility with a standard 16-Mb mask-programmable ROM (MROM) and is operative in either word-wide or byte-wide READ mode. Cell size and chip size are 2.2 μm×1.75 μm and 7.18 mm×17.39 mm, respectively     

Propagation characteristics of a dielectric-coated coaxial helicalwaveguide in a lossy medium

In this paper, the authors discuss the propagation characteristics of a dielectric-coated coaxial helical waveguide in a lossy medium. The authors place emphases on the phase constant, propagation modes, magnetic fields distribution, and attenuation constant, when permittivity of the internal region is relatively small, two propagation modes exist and dominant components of their magnetic fields are different. Lastly, the authors discuss the relation between the attenuation constant and permittivities     

Magnetic and magnetoelectric properties of self-assembled Fe₂.₅Mn₀.₅O₄ nanocrystals

We report magnetoresistance of -40%, corresponding to 80% spin polarization, at magnetic field of 0.5 T and 200 K for oleic acid-coated Fe(2.5)Mn(0.5)O(4) nanocrystals (FMO NCs) self-assembled on a SiO(2)/Si substrate by drop casting fabrication. The FMO NCs exhibited spin glass transition around 150 K and nonlinear current-voltage (I-V) characteristics. Fowler-Nordheim plot of the I-V characteristics indicated that electrons tunnel directly barriers between the FMO NCs. Transmission electron microscopy revealed that the FMO NCs are elongated hexagon in shape with size of ～15 × 20 nm. The FMO NCs self-assembled in two-dimension hexagonal networks of collinear ferromagnetic moments. The [111] easy magnetization axis of each FMO NC was parallel to each other in the hexagonal arrays. Geometrically frustrated lattice of collinear ferromagnetic moments supports both a low and a high intergranular tunneling conductance for the self-assembled FMO NCs without and with magnetic fields, respectively.     

High temperature and high pressure H n.m.r. and e.s.r. studies on coal liquefaction reactions

Changes in chemical reactions during coal liquefaction of Yallourn brown coal and Akabira bituminous coal were monitored by using high temperature and high pressure ¹H n.m.r. A simple high temperature and high pressure e.s.r. cell was constructed and the variation in concentration of free radicals during coal liquefaction reactions was monitored under the same experimental conditions as for n.m.r. With the liquefaction and coking reaction, typical spectra of n.m.r. and e.s.r. were obtained and could distinguish the reaction steps: swelling; liquefaction; coking. The combination of high temperature and high pressure n.m.r. and e.s.r. is promising to the chemistry of coal liquefaction reactions.