L/S-band 140-W push-pull power AlGaAs/GaAs HFET's for digitalcellular base stations

An L/S band high-power and low-distortion AlGaAs/GaAs heterostructure field-effect-transistor amplifier has been developed. The amplifier employed two pairs of prematched GaAs chips mounted on a single package, and the total output power was combined in a push-pull configuration with a low-loss microstrip balun circuit. The developed amplifier demonstrated state of-the-art performance of 140 W output power with 11.5 dB linear gain at 2.2 GHz. In addition, it exhibited extremely low distortion performance, which is suitable for digital cellular base station system applications     

Evaluation on high temperature fracture toughness of CrMoV cast steel by small punch testing

Toughness of CrMoV cast steel for steam turbine casings operated at elevated temperature can be degraded during the operation. It is important to measure the degradation under operation to estimate the damage and the maintenance interval. However, conventional testing methods for fracture toughness require large specimens and it is impractical for successive operation after sampling these specimens.     

Reproducible on-off switching of solid-state luminescence by controlling molecular packing through heat-mode interconversion

Organic luminescent solids are attracting increasing interest in various fields of application. Modification or alteration of the chemical structures of their component molecules is the most common approach for tuning their luminescence properties. However, for dynamic tuning or switching of solid-state luminescence with high efficiency and reproducibility successful examples are limited as chemical reactions in the solid state frequently encounter insufficient conversion, one-way reactions or loss of their luminescence properties. One promising approach is to control the luminescence properties by altering the mode of solid-state molecular packing without chemical reactions. Here, we show that 2,2':6',2'-terpyridine, practically non-luminescent in the form of amorphous solid or needle crystal, shows strong blue luminescence upon formation of a plate crystal. Efficient and reproducible on-off switching of solid-state luminescence is demonstrated by heat-mode interconversion between the plate and needle crystals. Because alteration of the mode of molecular packing does not require chemical reactions, the present findings would open the way for the development of novel organic luminescent solids that can be switched on and off by external thermal stimuli.     

Survey of the sensitivities of clinical isolates to antibacterial agents (annual report)

Research groups were formed in 21 institutions nationwide to investigate carbapenem resistance. The activities of various antibacterial agents, principally carbapenems were tested against clinical isolates collected from these institutions. The broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) of 17 antibacterial agents for 1,282 strains of 11 bacterial species isolated at all institutions between October and December 1995. The results were as follows: 1. Carbapenems exhibited strong antibacterial activities against MSSA and Streptococcus pneumoniae. Their activities against Enterococcus faecalis were comparable to that of ABPC. Carbapenems showed low activities against MRSA. 2. OFLX exhibited the greatest antibacterial activity against Haemophilus influenzae, followed by MEPM. The antibacterial activities of the other carbapenems were comparable to those of FMOX and CTM. 3. The carbapenems showed high activities against Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Bacteroides fragilis group. Their activities were greater than that exhibited by other beta-lactam antibacterial agents. The carbapenems also exhibited greater antibacterial activities against Serratia marcescens than the other beta-lactam antibacterial agents, but some resistant strains were detected. 4. The antibacterial activities of carbapenems against Pseudomonas aeruginosa were comparable to those of CAZ, AZT, AMK.     

Effects of small amount of additional elements on control of interstitial impurities and mechanical properties of V-4Cr-4Ti-Si-Al-Y alloys

In order to improve the mechanical properties of low activation vanadium alloys for fusion structural applications, effects of small addition of Si, Al and Y on the control of interstitial impurities (O, C and N) during the fabrication process were examined for several V-4Cr-4Ti-Si-Al-Y alloys produced by the levitation melting method. Charpy impact tests and tensile tests were carried out for five kinds of V-4Cr-4Ti-Si-Al-Y alloys using miniaturized specimens for the purpose of evaluating the effects of these elements on mechanical properties. Oxygen concentration decreased almost linearly with increasing loss of yttrium during melting. This oxygen reduction with yttrium loss during the melting process may have been achieved by two types of mechanisms, they are, (i) suppression of oxygen penetration into the molten materials from the environment and (ii) getting of oxygen from the matrix by forming Y₂O₃, which floats to the surface during the melting. There was no effect of Si and Al addition to control the concentration of interstitial impurities. V-4Cr-4Ti-0.1Si-0.1Al-0.1Y alloy showed the best impact properties out of the alloys investigated. Upper-shelf energy of the alloys decreased with increasing yttrium content. High number density of coarse inclusions containing yttrium could cause the degradation of impact properties, though they hardly affect tensile properties of the alloys. Even at higher yttrium contents, V-4Cr-4Ti-Y alloys without addition of Si and Al showed relatively high upper-shelf energy.     

Eumycotic mycetoma of the lower leg

Eumycotic mycetomas are extremely rare diseases in Japan. Only four cases have been reported. In the present report, eumycotic mycetoma of right lower leg of a 44-year-old male of Thai origin, resident in Japan for more than five years, was presented. An induration was noticed on the antero-medial side beneath the knee. Computed tomography showed slightly high dense subcutaneous mass-like lesion at the medial side of the right tibia. Though no draining sinus was formed, histologic examination disclosed grains composed of septated hyphae with Splendore-Hoeppli material. Since more people from foreign countries tend to reside in Japan, physicians and pathologists should be aware of various infections which are not commonly found in Japan.     

Motor Core Iron Loss Analysis Evaluating Shrink Fitting and Stamping by Finite-Element Method

We describe a method to analyze the effects of shrink fitting and stamping on the mechanical stress distribution and iron loss in motor cores. Shrink fitting and stamping are important processes in manufacture of motor cores from electrical steel. The mechanical stress distribution is evaluated by a structural finite-element method, and the iron loss is evaluated by combined analysis of the electromagnetic field (by a finite-element method) and mechanical stress. The method clearly shows that the iron loss becomes larger as the width of the shrink fit increases, an effect borne out by experiment. In regard to the effect of stamping, calculation results again agree well with experimental data     

In Situ PD-L1 Expression in Oral Squamous Cell Carcinoma Is Induced by Heterogeneous Mechanisms among Patients

The expression of programmed death ligand-1 (PD-L1) is controlled by complex mechanisms. The elucidation of the molecular mechanisms of PD-L1 expression is important for the exploration of new insights into PD-1 blockade therapy. Detailed mechanisms of the in situ expression of PD-L1 in tissues of oral squamous cell carcinomas (OSCCs) have not yet been clarified. We examined the mechanisms of PD-L1 expression focusing on the phosphorylation of downstream molecules of epidermal growth factor (EGF) and interferon gamma (IFN-γ) signaling in vitro and in vivo by immunoblotting and multi-fluorescence immunohistochemistry (MF-IHC), respectively. The in vitro experiments demonstrated that PD-L1 expression in OSCC cell lines is upregulated by EGF via the EGF receptor (EGFR)/PI3K/AKT pathway, the EGFR/STAT1 pathway, and the EGFR/MEK/ERK pathway, and by IFN-γ via the JAK2/STAT1 pathway. MF-IHC demonstrated that STAT1 and EGFR phosphorylation was frequently shown in PD-L1-positive cases and STAT1 phosphorylation was correlated with lymphocyte infiltration and EGFR phosphorylation. Moreover, the phosphorylation pattern of the related molecules in PD-L1-positive cells differed among the cases investigated. These findings indicate that PD-L1 expression mechanisms differ depending on the tissue environment and suggest that the examination of the tissue environment and molecular alterations of cancer cells affecting PD-L1 expression make it necessary for each patient to choose the appropriate combination drugs for PD-1 blockade cancer treatment.