Development of the new polymer insulating materials for HVDC cable

The properties of modified HDPE, selected from various polymer materials by evaluations of DC characteristics, were examined in both sheet and cable samples. It was found that the modification, which introduced a small amount of polar group into HDPE, considerably enhanced DC breakdown strength to as high as 1.5-2.0 times those of XLPE (cross-linked polyethylene). Under a poling voltage of up to 30 kV/mm, the modified HDPE exhibits particular behavior, with its space charge decreasing as stress is increasing. In addition, the additives in HDPE have a large influence on space-charge characteristics, thereby affecting the DC breakdown strength. The evaluation of cable insulated with optimum modified HDPE was conducted to determine the breakdown strength under various voltage applications. Compared with the XLPE cable, modified HDPE cable exhibited excellent characteristics under all kinds of voltage applications, particularly DC dielectric breakdown strength, which was almost twice that of XLPE     

Low-temperature polysilicon TFT with two-layer gate insulator usingphoto-CVD and APCVD SiO2

The performance of polysilicon thin-film transistors (TFTs) formed by a 600°C process was improved using a two-layer gate insulator of photochemical-assisted vapor deposition (photo-CVD) SiO₂ and atmospheric-pressure chemical vapor deposition (APCVD) SiO₂. The photo-CVD SiO₂, 100 Å thick, was deposited on polysilicon and followed by APCVD SiO₂ of 1000 Å thickness. The TFT had a threshold voltage of 8.3 V and a field-effect mobility of 35 cm²/V-s, which were higher than those of the conventional TFT with a single-layer gate SiO₂ of APCVD. Hydrogenation by hydrogen plasma was more effective for the new TFT than for the conventional device     

Site-directed mutagenesis study of the antibody 2D7 which catalyzes a reaction for insertion of Cu2+ into mesoporphyrin

Monoclonal antibody 2D7 generated against a transition-state analog N-methyl mesoporphyrin catalyzes a reaction for insertion of a cupric ion into mesoporphyrin. To investigate amino acid residues responsible for the catalytic activity, site-directed mutagenesis of the amino acid residues in the third complementarity determining region of the heavy chain (CDRH3) was performed on the antigen-binding fragment (Fab) of the antibody. Recombinant Fab mutants, in which Arg95 is replaced with Ala (R95A), Asp96 with Asn (D96N) and Met97 with Gly (M97G), were examined in terms of the catalytic efficiency of the reaction (k/K(S)) and the dissociation constant for N-methyl mesoporphyrin binding (K(d)) and these values were compared with those of the wild type. The k/K(S) values of the R95A and D96N mutants were 0.96% and 1.0% of that of the wild type, respectively, whereas the M97G mutant had no detectable catalytic activity. The K(d) values of the R95A and D96N mutants were 165 and 69 times that of the wild type, respectively, while that of the M97G mutant was similar to that of the wild type. The relationship between the k/K(S) and 1/K(d) values in the wild type and the R95A and D96N mutants suggests that Arg95 and Asp96 are responsible for stabilizing the transition-state in the catalytic reaction. The results of the M97G mutant allow us to propose that Met97 plays an important role in the catalytic activity probably due to a subtle and specific conformation of the antibody.     

Coronary artery bypass grafting in cases with poor left ventricular function

From January 1987 through June 1992, 18 patients with poor left ventricular function (left ventricular ejection fraction [LVEF] less than 0.3) underwent elective isolated primary coronary artery bypass surgery. The mean age was 56.4 years (range, 46 to 72 years), and 15 were males and 3 were females. Mean pre-operative LVEF measured by ventriculography was 0.26 +/- 0.03 (range, 0.19 to 0.30). Sixteen patients (88.9%) had a prior myocardial infarction and 9 (50%) had a history of congestive heart failure. Complete revascularization was the goal for all patients, and the mean number of bypass grafts was 3.0 +/- 0.8 per patient. The left anterior descending coronary artery (LAD) was revascularized in all patients. There were no operative deaths. Post-operative LVEF improved significantly from 0.26 +/- 0.03 to 0.42 +/- 0.11 (p = 0.0002), and the regional left ventricular wall motion improved in the diaphragmatic and posterobasal regions (p < 0.01). The patency of the grafts was 93.9% in all, and 100% for LAD. The mean follow-up period was 77 months, and the overall actuarial survival rate was 88.9% at 10 years. During follow-up periods, two patients died of congestive heart failure (CHF), and two required three rehospitalizations because of CHF. The overall cardiac event free rate was 75.8% at 10 years. In patients with poor left ventricular function, surgical revascularization can be performed safely, but congestive heart failure sometimes occurs during follow-up periods and may be the cause of death. Therefore alternate forms of therapy such as cardiac transplantation and/or TMLR should be considered in selected patients.     

Radical resection of primary malignant melanoma of the gallbladder with multiple metastases: report of a case

We present herein an usual case of primary malignant melanoma of the gallbladder in a 51-year-old man in whom an exploratory laparotomy for melena revealed six malignant melanoma lesions located in the gallbladder, main pancreatic duct, stomach, duodenum, jejunum, and a mesenteric lymph node. Total pancreatectomy was performed and histologically, junctional activity was seen only in the gallbladder, suggesting that this was the primary site. No melanotic lesions were found on the skin or eyes. The metastases to the main pancreatic duct and gastrointestinal tract appeared likely to have occurred as a consequence of the mucosal dissemination of the tumor cells shed into the bile. The post-operative course was uneventful and combined chemotherapy was administered for 16 months. No new metastatic lesions were found until 21 months postoperatively, when metastases were detected in the brain and thoracic spinal cord. These metastatic tumors were removed surgically, but the patient died from cerebral disturbance 26 months after the initial operation. Thus, we consider that aggressive surgical therapy was effective for extending the survival time and improving the quality of life of this patient.     

Crystal structure of poly[bis(3,4-dimethylphenoxy)phosphazene]

The crystal structure and chain conformation of poly[bis(3,4-dimethylphenoxy)phosphazene] — PB (dMe) PP — have been studied by X-ray diffraction techniques. The unit cell of this polymer shows an orthorhombic form with the crystallographic parameters a=2.05, b=1.49, c (chain axis)=0.998 nm. Its space group is determined as Pbcn-D _2h ¹⁴ where the molecular chains are located at the centre and each corner of the unit cell, which contains eight monomeric units; these molecular chains possibly have a — (trans ₃ cis)₂-conformation. The R factor calculated from the final crystal structure was estimated as 16.9%. As with other types of polyorganophosphazenes, the thermotropic transformation in PB (dMe) PP takes place from the three-dimensionally ordered state to its two-dimensional psuedohexagonal form (a _h = 1.49 nm), accompanied by a latent heat change at 96 °C.     

Efficacy of granisetron in the prevention of emesis induced by conditioning chemotherapy for allogeneic bone marrow transplantation

We conducted this study to compare granisetron, 5-HT3 antagonist, with conventional antiemetics in the prophylaxis of emesis induced by conditioning chemotherapy for allogeneic bone marrow transplantation in 41 patients. The conditioning chemotherapy regimen included either cytosine arabinoside 2 g/m2 x 4 and cyclophosphamide 60 mg/kg x 2 (CA, CY), or busulfan 4 mg/kg x 4 and cyclophosphamide 60 mg/kg x 2 (BU, CY). In CA and CY regimen, the clinical effective rate with granisetron against emesis was 94.1% on the 1st day, compared with 7.6% in the control group. On day 2 and 3, the effective rate with granisetron was 58.8% and 23.5%, respectively, compared with 0% in the control group. In the BU and CY regimen, control of emesis with granisetron on day 5 and 6 was 66.7%, against 20.0% in the control group. Based on these data, we concluded granisetron is superior to conventional antiemetics in the prophylaxis of emesis induced by conditioning for allogeneic bone marrow transplantation.     

Novel method for producing amorphous rice flours by milling without adding water

The present study investigated a novel milling method for producing amorphous rice starch without adding water. A new type of milling machine was developed (termed the shear and heat milling machine (SHMM)), which is capable of applying mechanical shear and heat during the milling process. The SHMM consisted of a pair of rice mortars attached to a servomotor and a ring heater. The heater was installed on the upper mortar; the temperature of the upper mortar was monitored and controlled by a thermal controller. Wide‐angle X‐ray diffraction (WAXD) analysis was used to determine the crystallinities of starch in rice flour samples produced using the SHMM at different milling temperatures. The WAXD data for milled rice flour that had been heated exhibited no diffraction peaks. This experimental result demonstrates that the developed SHMM produces amorphous rice starch easily by milling with heating without the addition of water. The milling conditions such as the shear and heat applied can be used to control the crystallinity of starch in rice.     

Effects of Light‐Induced Regularity on the Physical Properties of Multiphase Polymers

A method that combines UV irradiation and pausing was developed to manipulate the regularity and the length scales of the morphology generated by phase separation in full‐interpenetrating polymer networks of polystyrene and poly(methyl methacrylate). Upon increasing the pause time of photopolymerization and photo‐crosslink processes, the morphology gradually changes from hexagonal‐like packing to random structures. The width of the loss tan δ obtained for these phase‐separated materials changes with the morphological regularity, suggesting a potential technique for fabrication of mechanical bandgap materials.

     

Epithelial Cell Transformation and Senescence as Indicators of Genome Aging: Current Advances and Unanswered Questions

The recent advances in deciphering the human genome allow us to understand and evaluate the mechanisms of human genome age-associated transformations, which are largely unclear. Genome sequencing techniques assure comprehensive mapping of human genetics; however, understanding of gene functional interactions, specifically of time/age-dependent modifications, remain challenging. The age of the genome is defined by the sum of individual (inherited) and acquired genomic traits, based on internal and external factors that impact ontogenesis from the moment of egg fertilization and embryonic development. The biological part of genomic age opens a new perspective for intervention. The discovery of single cell-based mechanisms for genetic change indicates the possibility of influencing aging and associated disease burden, as well as metabolism. Cell populations with transformed genetic background were shown to serve as the origin of common diseases during extended life expectancy (superaging). Consequently, age-related cell transformation leads to cancer and cell degeneration (senescence). This article aims to describe current advances in the genomic mechanisms of senescence and its role in the spatiotemporal spread of epithelial clones and cell evolution.