Efficient Excitation of Hybrid Modes in a THz Clinotron

Journal of Infrared, Millimeter, and Terahertz Waves - Various regimes of hybrid, bulk-surface, modes being excited in the clinotron oscillator with a sheet electron beam and nonuniform grating...     

Analysis of class D inverter with irregular driving patterns

This paper presents an analysis of Class D inverter when irregular driving patterns are given to the gate drive of the switch devices. The analysis has been carried out with focusing on the waveforms, harmonics, low-frequency components, output power, and equivalent dc resistance, which are numerically analyzed and discussed. Class D inverters with six different Q factors from 0.1 to 20 are analyzed about 2/sup 16/ driving patterns for each Q. Superior four models of the six inverters are built and tested in circuit experiments. The calculated waveforms are compared to the experimental results. Both of them are agreed well in time domain and frequency domain. Analytical results show a possibility of a novel control method with irregular driving patterns. In spite of discontinuous control, the output power or voltage can be strictly changed as if continuous using the selected driving patterns in some ranges.     

Carbon Nanotubes Grown on the Surface of Cathode Deposit by Arc Discharge

Carbon nanotubes prepared by de arc discharge of graphite electrodes in He and CH₄ gas took markedly different morphology. Thick nanotubes embellished with many carbon nanoparticles were obtained by evaporation under high CH₄ gas pressure and high arc current. Thin and long carbon nanotubes were obtained under a CH₄ gas pressure of 50Torr and an arc current of 20A for the anode with a diameter of 6mm.     

Use of a YAP1 overexpression cassette conferring specific resistance to cerulenin and cycloheximide as an efficient selectable marker in the yeast Saccharomyces cerevisiae.

Drug-resistance markers for yeast transformation are useful because they can be applied to strains without auxotrophic mutations. However, they are susceptible to technical difficulties, namely lower transformation efficiency and the appearance of drug-resistant mutants without the marker. To avoid these problems, we have constructed a phosphoglycerate kinase (PGK) promoter-driven YAP1 expression cassette, called PGKp-YAP1. Yeast cells containing PGKp-YAP1 were resistant to cycloheximide, a protein synthesis inhibitor, and also to cerulenin, a fatty acid synthesis inhibitor, but not to other drugs tested. The transformation efficiency of PGKp-YAP1 using cerulenin selection was comparable to that using a URA3 auxotrophic marker when low concentrations of cerulenin were used. Non-transformed drug-resistant colonies did appear on the low-concentration cerulenin plates. However, these non-transformed colonies could easily be identified, based on their cycloheximide sensitivity and/or their resistance to aureobasidin A to which the transformants were sensitive. Therefore, the dual drug resistance of PGKp-YAP1 could be used as an effective selection for PGKp-YAP1 recipient cells. The PGKp-YAP1 marker was used to disrupt the LYS2 gene and to transform an industrial yeast strain, indicating that this marker can be used for efficient and reliable gene manipulations in any Saccharomyces cerevisiae strain.     

Monte Carlo simulation of hydrogen absorption in palladium and palladium–silver alloys

A modified Monte Carlo (MC) simulation was performed to investigate the hydrogen absorption behavior in Pd and Pd–Ag alloys of the composition Pd_xAg_1−x (x=0.7–0.8) under H₂ pressure (0.1 MPa) at different temperatures. The present method employed can consider the dissociative adsorption of hydrogen molecule and the subsequent absorption of hydrogen atom by formalizing the relationship between the pressure of hydrogen molecule and hydrogen atom. The potential parameters were determined to reproduce the solution enthalpy of hydrogen in pure metals. The results are in good agreement with experimental findings as well as previous theoretical studies. We confirmed that our method is useful to simulate the absorption of hydrogen in metals and alloys.     

MITI projects on recycling

MITI has actively done R&D on industrial technology for waste and reclamation and so there are many research items from small scale to large scale. However, Ecofactory and researches on recycling of metallic materials are introduced here. Ecofactory was proposed by the Mechanical Engineering Laboratory and is now at the stage of the Leading Research, a new research scheme in AISt. Researches on recycling of metallic materials are being done with subsidy. Those researches should contribute to both the preservatin of the global environment and effective recycling of waste materials.Abbreviations AIST Agency of Industrial Science and Technology - MITI Ministry of International Trade and Industry - NEDO New Energy and Industrial Technology Development Organization     

R & D Needs - Drying of Ceramics

New research and development needs for the drying of ceramics are prooosed. The researches on the ceramic drying are briefly reviewed and the role of the drying in the ceramic production process iS summarized. The drying must deal with molded materials and the problem is of significant difference from another drying with particulate materials. It means that the drying must be performed with keeping the molded feature and the insufficient completion of drying and the careless operation influence directly on the product quality The importnance of the R & D on the heat and moisture transfer. shrinking mechanism. the deformation behavior and the strain-stress formation in the molded clay issuggested. The subjects are also pointed out for the further improvement of the ceramic drying process and the precise design of molding with high quality.     

Halo congenital nevus undergoing spontaneous regression. Involvement of T-cell immunity in involution and presence of circulating anti-nevus cell IgM antibodies

BACKGROUND: Halo congenital nevus is a condition in which halo formation is associated with congenital nevocellular nevi. Although several theories have been proposed, the immunologic mechanisms of halo formation and concomitant nevus regression still remain unclear. We presented immunologic findings in a case of halo congenital nevus with unique histologic location of inflammatory cells. OBSERVATIONS: Histologically, the present case of halo congenital nevus undergoing spontaneous regression showed a marked inflammatory infiltrate with remnants of original nevus cell nests. In the infiltrating T cells, CD8+ cells outnumbered CD4+ cells and the infiltrate of natural killer cells was not substantial. Direct and indirect immunofluorescence studies demonstrated the presence of IgM antibodies against nevus cells as well as melanoma cells and cultured melanocytes in the patient's serum. CONCLUSIONS: Our findings suggest that both T-cell-mediated immunity and IgM antibodies may be involved in the regression of halo congenital nevus. However, it is important to point out that our results may simply be epiphenomena and not directly responsible for the destruction of nevus cells.     

Two cases of cancer with bone metastases treated with local therapy

Two cases with osteolytic bone metastases from cervical cancer and esophageal cancer treated by local therapy were reported. The first case is a 53-year-old female with bone metastases of left ischium developed 1 year after hysterectomy. She was treated by intratumor injection of sizofiran (SPG) 20 mg/w and radiation therapy. After 4 weeks, ischias pain decreased and bone lesion showed remarkable calcification (PR) 8th months later. The second case is a 58-year-old male with bone metastases of the left tibia and fibula developed 1 year after surgery. He was treated by intratumor injection of SPG 20 mg/w x 4 and OK-432 1.0 KE/w x 8 after radiation therapy. After 4 weeks, pain and swelling of left leg decreased and bone lesions showed remarkable calcification (PR) three months later. We suggest that intratumor injection of SPG and OK-432 with radiation therapy was effective for osteolytic bone metastases.