Direct-linked-type frequency changer based on DC-clamped bilateralswitching circuit topology

This paper describes a direct-linked-type frequency changer (DLT-FC) proposed by the authors. The DLT-FC is a converter circuit with a new configuration for direct frequency change. The DLT-FC does not require a DC-link circuit, nor bilateral switches. In addition, DC snubber circuits can be applied without the need for a regenerative circuit of snubber energy. Therefore, the DLT-FC can be designed to be compact and lightweight, and have a long life. The authors made a prototype of the DLT-FC and experimentally checked its operation. The results indicate that the performance of the DLT-FC makes it suitable for industrial use     

Superconducting Coupling Nature at Grain Boundaries in Bi2Sr2CaCu2Ox Glass-Ceramics

Superconducting coupling nature at grain boundaries in Bi₂Sr₂CaCu₂O _x glass-ceramics consisting mainly of the low- T _c phase was first examined by measuring superconducting properties and temperature or ac field dependence of ac complex susceptibility. It was found from the ac loss peaks that superconducting coupling at grain boundaries was basically characterized by three types of weak links. The weak-link behaviors at grain boundaries depended strongly on cooling conditions after annealing and annealing time and temperature. Particularly, it was found that the weak links at grain boundaries were improved by prolonged annealing at 840°C. The furnace-cooled glass-ceramics obtained by annealing at 820° or 840°C for about 200 h exhibited a critical transport current density (77 K, zero magnetic field) of about 200 A/cm².     

Energy transmission transformer for a wireless capsule endoscope: analysis of specific absorption rate and current density in biological tissue

This paper reports on the electromagnetic influences on the analysis of biological tissue surrounding a prototype energy transmission system for a wireless capsule endoscope. Specific absorption rate (SAR) and current density were analyzed by electromagnetic simulator in a model consisting of primary coil and a human trunk including the skin, fat, muscle, small intestine, backbone, and blood. First, electric and magnetic strength in the same conditions as the analytical model were measured and compared to the analytical values to confirm the validity of the analysis. Then, SAR and current density as a function of frequency and output power were analyzed. The validity of the analysis was confirmed by comparing the analytical values with the measured ones. The SAR was below the basic restrictions of the International Commission on Nonionizing Radiation Protection (ICNIRP). At the same time, the results for current density show that the influence on biological tissue was lowest in the 300-400 kHz range, indicating that it was possible to transmit energy safely up to 160 mW. In addition, we confirmed that the current density has decreased by reducing the primary coil's current.     

Degradation evaluation of poly-Si TFTs by comparing normal and reverse characteristics and behavior analysis of hot-carrier degradation

We propose degradation evaluation of poly-Si TFTs by comparing normal and reverse characteristics. Since symmetrical normal and reverse characteristics indicate Joule-heating degradation whereas asymmetrical characteristics indicate hot-carrier degradation, they can be clearly and easily classified. Moreover, degradation occurrence is contrasted between standard and fine TFTs. Finally, behavior of the hot-carrier degradation is analyzed.     

Encapsulation of lead-free Sn/Zn/Bi solder alloy particles by coating with wax powder for improving oxidation resistance

An encapsulation treatment of lead-free Sn/Zn/Bi solder powder was investigated for improving the oxidation resistance. Sn-8mass%Zn-3mass%Bi alloy particles were coated with a wax (12-hydroxystearic acid) powder by means of a dry mechanical treatment method using a ball mill. In order to determine the optimum operating conditions of the ball mill in the wax-coating treatments, the compressive energy required for deforming a single Sn/Zn/Bi alloy particle was measured with an unconfined compression tester and the mechanical energy applied to the alloy particles in the ball mill was estimated using the results of the compression test. The optimum operating conditions were determined based on both the applied energy and the flowability of solder pastes, and the wax-coated alloy particles maintaining the spherical shape were obtained under the conditions. The wettability test and the solder balling test for the solder pastes containing the wax-coated alloy particles stored at room temperature in air were carried out to evaluate the oxidation resistance performance. The wax-coated alloy particles had an excellent wettability compared with the original alloy particles, and the oxidation resistance of the Sn/Zn/Bi solder powder was improved by the encapsulation treatment.     

Identification of a methanol-inducible promoter from Rhodococcus erythropolis PR4 and its use as an expression vector

The genus Rhodococcus exhibits a broad range of catalytic activity and is tolerant to various kinds of organic solvents. This property makes rhodococci suitable for use as a whole-cell catalyst. Various tools for genetic engineering have been developed to use Rhodococcus erythropolis as a host for bioconversion. In this study, we investigated the protein expression responses of R. erythropolis strains and found that isocitrate lyase production in R. erythropolis PR4 (ICL(Re)) was induced by methanol. By analyzing the regulation mechanisms of icl(Re) expression, the ~200-bp upstream region from the first nucleotide of the translation initiation codon of icl(Re) was shown to be sufficient for the methanol-inducible expression. Also, the ~100-bp upstream region exhibited strong constitutive promoter activity by an unknown mechanism(s). By investigating proteins that bound to the upstream region of icl(Re)in vitro, a RamB homologue of R. erythropolis PR4 (RamB(Re)) was identified. Moreover, 2 putative RamB(Re) binding sites were identified in the upstream region of icl(Re) through pull-down assays. A ramB(Re) knockout experiment suggested that RamB(Re) negatively controlled the expression of icl(Re) and that RamB(Re) regulation was dependent on the availability of a carbon source. On the basis of these findings, we were able to create novel methanol-inducible and strong constitutive expression vectors.     

Characterization of polystyrene-binding peptides (PS-tags) for site-specific immobilization of proteins

In this study, we characterized polystyrene-binding peptides (PS-tags) that possess a specific binding affinity for hydrophilic polystyrene (phi-PS) plates. Both the FITC-labeled PS19-1 (RAFIASRRIKRP) and PS19-6 (RIIIRRIRR) peptides showed strong binding affinity for commercially available hydrophilic, but not hydrophobic, PS plates in the presence of the non-ionic surfactant Tween 20. The dissociation constants (K_d) of the PS19-1 and PS19-6 peptides for the hydrophilic PS-A plate were 169 and 86 nM, respectively, and the K_d of both peptides increased with the concentration of NaCl or urea. Based on adsorption yield and residual activity of glutathione S-transferase (GST) after fusion with the PS19-6 peptide or its variants, it was found that the basic amino acid in the PS-tags, i.e., Arg was essential for the strong binding affinity of PS-tags in both the peptide and peptide-fused protein forms The aliphatic amino acids in PS19-6 and PS19-6L, such as Ile or Leu, were also effective. Thus, a series of PS-tags that possess this unusual feature, especially the peptides PS19-6 (RIIIRRIRR) and PS19-6L (RLLLRRLRR), are potential candidate affinity peptide tags for site-specific immobilization of proteins onto hydrophilic PS plates, which show potential as solid supports for protein-based biochips.     

Accumulation and elimination profiles of paralytic shellfish poison in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Gymnodinium catenatum

The paralytic shellfish poison (PSP)-producing dinoflagellate Gymnodinium catenatum (Gc) was fed to the short-necked clam Tapes japonica, and the accumulation, transformation and elimination profiles of PSP were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested most of the Gc cells (4 x 10(6) cells) supplied as a bolus at the beginning of the experiment, and accumulated a maximal amount of toxin (181 nmol/10 clams) after 12 hr. The rate of toxin accumulation at that time was 16%, which rapidly decreased thereafter. During the rearing period, a variation in toxin composition, derived presumably from the transformation of toxin analogues in the clams, was observed, including a reversal of the ratio of C2 to C1, and the appearance of carbamate (gonyautoxin (GTX) 2, 3) and decarbamoyl (dc) derivatives (decarbamoylsaxitoxin (dcSTX) and dcGTX2, 3), which were undetectable in Gc cells. The total amount of toxin contained in clams and residue (remaining Gc cells and/or excrement in the rearing tank) gradually declined, and only about 1% of the supplied toxin was detected at the end of the experiment.     

Cytokine responses of human intestinal epithelial-like Caco-2 cells to the nonpathogenic bacterium Bacillus subtilis (natto)

Intestinal epithelial cells produce cytokines in response to pathogenic bacteria. However, cellular responses of these cells to nonpathogenic strains, such as Bacillus subtilis, are yet to be determined. In this study, we investigate whether epithelial-like human colon carcinoma Caco-2 cells produce cytokines in response to B. subtilis or B. subtilis (natto). The latter strain is utilized for manufacturing the fermented soy food "natto". Live cells of nonpathogenic B. subtilis JCM 1465(T), B. subtilis (natto) and E. coli JCM 1649(T), as well as pathogenic S. enteritidis JCM 1652 and P. aeruginosa JCM 5516 strains, induced secretion of interleukin-6 (IL-6) and/or IL-8, but not IL-7, IL-15 or tumor necrosis factor alpha (TNF-alpha). Transepithelial electrical resistance (TER) of Caco-2 cell monolayers cultured with E. coli, S. enteritidis or P. aeruginosa decreased more rapidly than that of cells cultured with B. subtilis or B. subtilis (natto). The amounts of cytokine induced by B. subtilis (natto) cells were strain-dependent. Moreover, B. subtilis (natto) cells subjected to hydrochloric acid treatment, but not autoclaving, induced a higher secretion of IL-6 and IL-8 than intact cells. Tyrosine kinase inhibitors, including AG126 and genistein, suppressed cytokine secretion. Our results suggest that the nonpathogenic B. subtilis (natto) bacterium induces cytokine responses in intestinal epithelial cells via activation of an intracellular signaling pathway, such as that of nuclear factor-kappa B (NF-kappaB).