Fundamental study of narrow-gap welding with oscillation laser beam

Laser welding with oscillation laser beams enables control of the heat input distribution. In this study, we attempted to develop a narrow-gap welding process with oscillation laser welding. This process is expected to prevent a lack of fusion because the entire bottom to the groove can be melted by the oscillation laser. As the first step of the study, bead-on-plate welding experiments with an oscillation laser beam were performed to investigate the relationship between the welding conditions and welding results. The experiments revealed that the oscillation conditions strongly affect the welding penetration shape. It was clarified that the wire melting phenomena in oscillation laser welding differed from those of straight (non-oscillation) laser welding. Additionally, narrow-gap laser welding experiments were performed to investigate the relationship between the oscillation conditions and gap width. The results confirmed the effectiveness of oscillation laser welding for narrow-gap welding.     

High-throughput screening of improved protease inhibitors using a yeast cell surface display system and a yeast cell chip

Protease-targeted inhibitors have been promising pharmaceuticals. Here, we combined a yeast cell surface display system with a yeast cell chip for the high-throughput screening of protease inhibitors, and succeeded in improving the activity of a protease inhibitor.     

Anti-Proliferative Activities and Apoptosis Induction by Triterpenes Derived from Eriobotrya japonica in Human Leukemia Cell Lines

Eriobotrya japonica leaf is a traditional herbal medicine that contains numerous triterpenes, which have various pharmacological properties. In this study, we investigated the anti-proliferative activity of four triterpenes derived from E. japonica, including corosolic acid (CA), ursolic acid (UA), maslinic acid (MA) and oleanolic acid (OA), in human leukemia cell lines. CA showed the strongest anti-proliferative activity in all of the leukemia cell lines tested, but not in normal human skin fibroblast cell lines. To determine the mechanism underlying the anti-proliferative effect of CA, we examined the effect of CA on molecular events known as apoptosis induction. CA induced chromatin condensation, DNA fragmentation, sub-G₁ phase DNA, activation of caspase-3, -8 and -9 and the cleavage of PARP in HL-60. CA also activated Bid and Bax, leading to the loss of mitochondrial membrane potential (Δψ_m) and cytochrome c release into the cytosol, whereas Bcl-2 and Bcl-xL were unaffected by CA. These results suggest that CA has an anti-proliferative effect on leukemia cells via the induction of apoptosis mediated by mitochondrial dysfunction and caspase activation. CA may be a potential chemotherapeutic agent for the treatment of human leukemia.     

Boundary Lubrication Properties of Nanoperiod Solid Lubricant Multilayer Films Composed of Diamond-Like Carbon and Gold Layers

To develop electroconductive and high-endurance solid lubricant nanoperiod multilayer (DLC/Au)_n films, diamond-like carbon (DLC) and gold layers were deposited while controlling the time the substrate was exposed graphite and gold targets. The electrical resistivity of the (DLC/Au)_n multilayer films was ~12.4 Ω cm. The hardness of the (DLC/Au)_n multilayer films was similar to that of DLC films and much higher than that of gold monolayer films. According to the results of oscillating sliding tests under water boundary lubrication and dry conditions, (DLC/Au)_n multilayer films exhibited the low friction coefficient, little damage, and high sliding durability than the monolayer films. (DLC/Au)_n films also have a lower friction coefficient and exhibit less damage than a Au monolayer under polyalphaolefin boundary lubrication.     

Differential requirements of CD45 protein tyrosine phosphatase for cytolytic activities and intrathymic and extrathymic development of intestinal intraepithelial lymphocytes

CD45 is a transmembrane protein tyrosine phosphatase essential for Ag receptor-mediated signaling in both T and B cells. In this study we investigated roles of CD45 in development and cytolytic activities of murine intestinal intraepithelial lymphocytes (i-IEL) using CD45 exon 6 knockout (CD45-/-) mice. Interestingly, the total cell number of i-IEL was significantly reduced in CD45-/-mice during aging (10-20 wk of age), whereas the i-IEL number was normally increased in the wild-type littermates. Especially, the number of gamma(delta)TCR+ i-IEL decreased markedly in CD45-/- mice during aging. The i-IEL in CD45-/- mice were more susceptible to in vitro spontaneous apoptosis than the normal i-IEL, implying that CD45 is required for maintenance of the cellularity of i-IEL. Results from in vivo analyses of the extrathymic and intrathymic development of i-IEL suggested that CD45-mediated signaling is required for the intrathymic, but not the extrathymic, development of i-IEL. Moreover, the whole i-IEL from CD45-/- mice showed a significantly reduced cytolytic activity, and the residual cytolytic activity was completely diminished by depleting CD45+ i-IEL, suggesting that CD45 is indispensable for the TCR-mediated cytolytic activity of i-IEL. Furthermore, we found differential contributions of CD45 and p56lck to development and induction of cytolytic activities of i-IEL.     

Normal B lymphocyte development but impaired T cell maturation in CD45-exon6 protein tyrosine phosphatase-deficient mice

The transmembrane tyrosine phosphatase CD45 is expressed in multiple isoforms on all nucleated hematopoietic cells, resulting from alternative splicing of variable exons. We generated mice with a mutation in the variable CD45 exon 6, using homologous recombination. In mice homozygous for the CD45-exon6 mutation, B cells and most T cells did not express CD45. Development of B cells appeared normal, although Ig mu-induced proliferation was completely abrogated. Thymocyte maturation was blocked at the transitional stage from immature CD4+CD8+ to mature CD4+ or CD8+ cells, and only a few T cells could be detected in peripheral lymphoid organs. Clonal deletion of superantigen-reactive T cells still occurred. Cytotoxic T cell responses to lymphocytic choriomeningitis virus were absent in CD45-exon6-/- mice. These data imply that CD45 is differentially required for the development and function of B and T lymphocytes.     

Large dose natural interferon alpha therapy for patients with chronic hepatitis C

To evaluate the efficacy of large dose interferon treatment for patients with chronic hepatitis C virus (HCV) infection, we studied 99 Japanese patients treated with either 6 million units (MU) or 9 MU natural interferon alpha. Serum samples were tested for HCV RNA by polymerase chain reaction (PCR). HCV RNA genotypes were determined by PCR with type-specific preimers, and the HCV RNA level was measured by competitive PCR. HCV RNA was detected in all patients, prior to the initiation of treatment. We examined interleukin-1 receptor antagonist (IL-1 Ra) by enzyme-linked immunosorbent assay. Forty-four patients were treated with 9 MU natural interferon alpha for 24 weeks (group A), and fifty-five patients were treated with 6 MU natural interferon alpha for 24 weeks (group B). There were no significant differences in HCV RNA levels, HCV RNA genotype or histological activity index (HAI) score between the two groups. Of the 94 patients who completed this treatment, nine (23.1%) in group A and 14 (25.5%) in group B sustained elimination of HCV RNA throughout a 6-month follow-up. There were no differences in the rate of complete response when comparing HCV RNA genotype, levels and HAI score and no significant differences in elevation of IL-1 Ra levels between the two groups. Five of group A patients refused further treatment because of severe side effects such as retinal hemorrhage, while no patient in group B had severe side effects. Thus, large dose natural interferon alpha treatment confers no additional benefit to the patient, compared with the current use of a lower dose.     

A new strategy for management of retroperitoneal tumors with supradiaphragmatic vena caval thrombi

A 36-year-old woman had uneventful astigmatic myopic laser in situ keratomileusis (LASIK) to correct -12.00 -1.50 x 70. Three days later, she developed a corneal abscess, hypopyon, and an intense vitreous cellular reaction-endophthalmitis. The patient was immediately given intravenous ciprofloxacin and topical vancomycin and ceftazidime. The infecting organism was Streptococcus pneumoniae. One day after therapy was instituted, the hypopyon resolved. Seven months later, best corrected visual acuity was 20/25 and refractive error, -4.00 diopters. A stromal scar (grade 2 haze) was causing a slight reduction in acuity. Endophthalmitis after LASIK, if treated promptly, need not lead to a permanent reduction in visual acuity.     

Rheological properties of polypropylene/high-density polyethylene blend melts. I. Capillary flow properties

Three kinds of isotactic polypropylenes (PP) with different melt flow indexes (MFIs) were melt-blended with three kinds of high-density polyethylenes (HDPE) with different MFI using a screw extruder, and the morphologies and capillary flow properties such as flow curve, entrance effect, Barus effect, and melt fracture were studied. When HDPE contents were 70 wt % or above and PP particles formed the disperse phase, the size of the particles decreased with decreasing viscosity of PP. When HDPE contents were 30 wt % or below and HDPE particles formed the disperse phase, the size of the particles was minimum when the viscosities of PP and HDPE were similar. The die swell ratios of the blends were higher than those of the components. On the other hand, the entrance correction coefficients of the blends were intermediate between those of the components. There was no correlation between the die swell ratio and the entrance corretion coefficient. Therefore, it is not always appropriate to regard the entrance correction coefficient as a measure of melt elasticity in the case of inhomogeneous polymer systems such as PP/HDPE blend.     

Antibacterial Activity of Photocatalytic Titanium Dioxide Thin Films with Photodeposited Silver on the Surface of Sanitary Ware

The antibacterial activity of photocatalytic titanium dioxide (TiO₂) thin films with photodeposited silver on the surface of sanitary ware was studied. Samples were prepared by coating a TiO₂ sol that was calcined at 880°–980°C and photodeposited with silver ions onto the glazed layer of the sanitary ware. The relationships between the antibacterial activity and the fabrication conditions were investigated by X-ray diffractometry, scanning electron microscopy, and colorimetry. The phase of TiO₂ identified in the thin films was a mixture of anatase and rutile. The amount of rutile phase increased as the calcination temperature increased, and grain growth of the TiO₂ particles was observed. The activity was dependent on the TiO₂ thickness, the calcination temperature, and the amount of silver. These results suggest that the antibacterial activity was strongly affected by the amount of anatase in the thin films.