Radiotherapy for cervical cancer with high-dose rate brachytherapy correlation between tumor size, dose and failure

This is a retrospective analysis of 659 patients with cervical squamous cell carcinoma with a minimum follow-up of 2 years at Keio University Hospital between May 1974 and March 1990. All patients were treated with external radiation (50 Gy) and high-dose rate (HDR) intracavitary brachytherapy (20-34 Gy). The 5-year survival rates in each stage gradually decreased with the advance of the stage (I, 84%; II, 71%; III, 47%; and IVa, 12%). When 366 patients with stage III were classified into three groups according to tumor size, i.e. small (S, 102 patients), medium (M, 145) and large (L, 119), a survival gradient of small > medium > large was demonstrated and the differences between them were significant. At follow-up visits conducted between 1 and 2 months after completion of treatment, 135 patients (20%) had physical indications of residual disease. The larger the tumor size, the more likely was residual disease by 2 months. The patients with residual disease had a significantly higher rate of the pelvic failure than those without it. There was no significant correlation between radiation doses by RALS and pelvic failure rates, except in the stage III-L group. In the stage III-L group, intracavitary doses of 24 Gy or less to point A could be correlated with the higher pelvic failure rate and the lower survival rate, in contrast to doses of 27 Gy or more. The incidence of major rectosigmoid complications was 11.8% with doses of 24 Gy or less to point A, 8.1% with 27 Gy and 19.2% with doses of 30 Gy or more.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis and thermal transition of side-chain liquid crystalline polyoxetanes having laterally attached mesogenic group

Side-chain liquid crystalline polymers with laterally attached mesogenic group were synthesized. Polymers having polyoxetane main chain were obtained by cationic polymerization, and with polymethacrylate main chain by radical polymerization. Some of the polymers showed nematic phase, and polyoxetanes having mesogen with electron-withdrawing and electron-donating groups in the molecule showed a little more discrete mesophase.     

Reformation of hazardous wastes into useful supporting materials for fast reactor fuels

Novel concepts for effective utilization of molybdenum (Mo) from nuclear waste and magnesium silicates from hazardous asbestos wastes are proposed. A fast reactor cycle scheme that incorporates each material is described in the present paper. Results of basic studies on several fundamental technologies for the present cycle are given. Basic separation features of Mo by using the LIX63 microcapsule and tertiary pyridine resin were investigated. A simple chemical synthesis route for Mo precursor powder from Mo-containing HNO₃ solution was demonstrated. Effects of impurities in recovered Mo on sintering behavior of Mo-pellets were experimentally investigated.     

Analysis of organic solvent tolerance in Escherichia coli using gene expression profiles from DNA microarrays

To investigate the biological mechanism of organic solvent tolerance (OST), DNA microarrays were used to collect and compare the gene expression profiles of normal and organic solvent-tolerant Escherichia coli strains. First, we compared the tolerant-strain OST3410 to its sensitive parent strain JA300 in the absence of organic solvents. Numerous genes showed higher expression levels in OST3410, and Northern analysis was used to confirm the higher expression level of some genes. Next, the gene expression profiles of JA300 and OST3410 exposed to hexane as an organic solvent were investigated and compared with JA300 before exposure to organic solvent. In OST3410 and JA300, 115 and 47 hexane-induced genes were found, respectively. As candidates for genes related to OST, we focused on six genes: cysD, marA, mg1B, tnaA, tnaB and yihM, which were upregulated by hexane in both strains. When these genes were over-expressed on plasmids, only the marA plasmid increased OST activity. It should be noted that we succeeded in finding a gene related to OST activity using only DNA microarray data, without any biochemical or biological knowledge.     

Study of DC circuit breaker of H2‐N2 gas mixture for high voltage

Global warming caused by such gases as CO₂ is a subject of great concern. Automobile emissions are an especially great problem in this respect. Therefore, hybrid cars are being widely developed and used. Because hybrid cars use electric power and gasoline, their emissions of CO₂ are reduced. The electric motor of a hybrid car is driven by a battery, which has large capacity. Therefore, relays must interrupt a high DC current on switching between the electric motor and the gasoline engine, and hydrogen gas‐filled relays are used for the purpose. In interruption tests in which we investigated the basic characteristics of hydrogen gas, the DC current did not reach a current‐zero point. Thus, the current must be coerced to zero by using a high arc voltage. The loss coefficient and arc voltages of hydrogen are high, and we therefore performed interruption tests using a high arc voltage. Interruption tests and dielectric breakdowns test of air, pure hydrogen, and a hydrogen‐nitrogen mixture indicated that an 80%–20% H₂–N₂ mixture is the most effective. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(2): 9–17, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21042     

Thermoelectric properties of Ti1+xS2 prepared by CS2 sulfurization

Titanium disulfide (TiS₂) powder was prepared by sulfurizing TiO₂ powder with CS₂ gas at 1073 K for 4 h. Because CS₂ gas is a powerful sulfurizing agent for TiO₂, CS₂ sulfurization can be performed at a low temperature. The TiS₂ powder thus prepared was first mixed with sulfur powder in a mass ratio of 1:0.04 and pressure sintered at 973 K for 1 h under a uniaxial pressure of 50 MPa in vacuum. The addition of a small amount of sulfur powder to the TiS₂ powder prevents sulfur deficiency in the sintered compact, resulting in the formation of a near-stoichiometric Ti_1.008S₂ composition. X-ray diffraction patterns show that the crystalline ab-axis is preferentially oriented perpendicular to the pressing direction. The Seebeck coefficient, electrical resistivity and thermal conductivity of the oriented TiS₂ sintered compacts with near-stoichiometric and sulfur-poor (titanium-rich) compositions were measured in the temperature range 300–723 K. The thermoelectric figure of merit ZT was enhanced by prevention of sulfur deficiency and formation of the oriented texture. The highest ZT of 0.34 was observed at 663 K in Ti_1.008S₂ for the direction perpendicular to the pressing axis.     

Dynamic Interface Formation in Magnetic Thin Film Heterostructures

Magnetic thin film heterostructures have been widely studied for fundamental interests in the emergence of novel phenomena associated with the heterointerface formation as well as their promising practical potential. Combining X‐ray magnetic circular dichroism with scanning tunneling microscopy, it is shown for fcc Fe thin films grown on Cu(001) with Mn overlayers (Mn/Fe thin film heterostructures) that the interfacial factors dominating the electronic and magnetic properties of the entire system dynamically change with the amount of the Mn overlayer. Element specific magnetization curves of the Fe layer exhibit a two‐step spin reorientation transition from out‐of‐plane to in‐plane direction by increasing the Mn coverage. The atomic‐scale characterizations of structural and electronic properties in combination with the first‐principles calculations successfully unravel the roles of the entangled interfacial factors and clarify the driving forces of the transition. The first step of the transition at a low Mn coverage is dominantly induced by the formation of FeMn disordered alloy at the heterointerface, and the electronic hybridization with the interfacial FeMn ordered alloy is dominant as the origin of the second step of the transition at a high Mn coverage.     

Unusual chain configuration of main-chain liquid crystal polyesters having Y-shaped mesogens in nematic phase

The nematic liquid crystals of main-chain liquid crystalline (MCLC) Y-n polyesters were investigated and compared with those of conventional MCLC L-n polyesters. Y-n polyesters have Y-shaped mesogens that are connected by spacers at their branch ends as an alternative to the columitic mesogens of L-n polyesters. The nematic phases of both polyesters under polarized optical microscopy exhibited Schlieren textures that are typical of uniaxial nematic liquid crystals. The isotropization temperature and entropy change estimated by differential scanning calorimetry show odd-even oscillations, which are characteristic of MCLC polymers, and the entropy change of Y-n are significantly smaller than those of L-n. Such a low entropy change is associated with the Y-n chain configuration, which is unusual for MCLC polymers, as revealed by X-ray diffraction and infrared dichroic spectroscopy. The uniaxial nematic structure is formed by Y-shaped mesogens arranging their trunks along the director direction and being rotated about their trunks without any correlation. Connecting these mesogens by using spacers that are placed preferentially along the director enables us to depict the chain that oscillates along the director direction and performs a random walk in the direction perpendicular to the director.     

Post-manufacturing, 17-times acceptable raw bit error rate enhancement, dynamic codeword transition ECC scheme for highly reliable solid-state drives, SSDs

A dynamic codeword transition ECC scheme is proposed for highly reliable solid-state drives, SSDs. By monitoring the error number or the write/erase cycles, the ECC codeword dynamically increases from 512 Byte (+parity) to 1 KByte, 2 KByte, 4 KByte…32 KByte. The proposed ECC with a larger codeword decreases the failure rate after ECC. As a result, the acceptable raw bit error rate, BER, before ECC is enhanced. Assuming a NAND Flash memory which requires 8-bit correction in 512 Byte codeword ECC, a 17-times higher acceptable raw BER than the conventional fixed 512 Byte codeword ECC is realized for the mobile phone application without an interleaving. For the MP3 player, digital-still camera and high-speed memory card applications with a dual channel interleaving, 15-times higher acceptable raw BER is achieved. Finally, for the SSD application with 8 channel interleaving, 13-times higher acceptable raw BER is realized. Because the ratio of the user data to the parity bits is the same in each ECC codeword, no additional memory area is required. Note that the reliability of SSD is improved after the manufacturing without cost penalty. Compared with the conventional ECC with the fixed large 32 KByte codeword, the proposed scheme achieves a lower power consumption by introducing the “best-effort” type operation. In the proposed scheme, during the most of the lifetime of SSD, a weak ECC with a shorter codeword such as 512 Byte (+parity), 1 KByte and 2 KByte is used and 98% lower power consumption is realized. At the life-end of SSD, a strong ECC with a 32 KByte codeword is used and the highly reliable operation is achieved. The random read performance is also discussed. The random read performance is estimated by the latency. The latency is below 1.5 ms for ECC codeword up to 32 KByte. This latency is below the average latency of 15,000 rpm HDD, 2 ms.