Ultrasonic investigations on the flux state of the organic superconductor κ-(BEDT-TTF)2Cu(NCS)2

The flux state of the organic superconductor -(BEDT-TTF)₂Cu(NCS)₂ has been investigated by ultrasonic measurements. The magnetic field dependence in the longitudinal sound velocity, shows a remarkable dip. The amount of the dip is proportional to cos, where is the angle between the propagation direction of the sound and the magnetic field. The magnetoresistance anomaly in this salt, which is seen in the same magnetic field range as for the sound velocity, has been interpreted by the thermal fluctuation of the Josephson coupling between the superconducting layers. The sound velocity anomaly is interpreted by this mechanism. It would be concluded that such anomaly is caused by a large Grüneisen parameter in this salt.     

Further discussion on the estimation of primary polymer chain length of vinyl-type network polymers based on the thermal decomposition of azo crosslinks

2,2′-Azobis[N-(2-propenyl)-2-methylpropionamide] (APMPA) having two carbon-carbon double bonds and an azo group was copolymerized with vinyl benzoate (VBz) at 60 °C, providing an azo groups containing VBz/APMPA prepolymer or crosslinked polymer which acts as a soluble or insoluble polymeric azo initiator, respectively. The gelation in VBz/APMPA (90/10 mol/mol) copolymerization was discussed briefly in order to reveal the characteristic polymerization behavior of APMPA as a novel crosslinker. Then, the resulting poly(VBz-co-APMPA)s as prepolymers or crosslinked polymers were thermally decomposed at elevated temperatures in the presence of lauryl mercaptan (LM) as a chain transfer agent; thus, the polymeric radicals generated through the cleavage of azo crosslinks would undergo the chain transfer reaction with LM to give primary polymer chains. This will provide a new approach to estimate the primary polymer chain length of vinyl-type network polymers by cutting all crosslinks in the network at the gel point as defined for the derivation of Stockmayer's equation.     

Vitreous phase coating on glaserite-type alkaline earth silicate blue phosphor BaCa2MgSi2O8:Eu

A simple solid-state reaction was used to apply a vitreous-phase coating onto Eu²⁺-doped BaCa₂MgSi₂O₈ blue-phosphor particles. The vitreous phase was generated by liquid phase sintering at 1200 °C. The coated phosphor exhibited resistant to an acid dispersant. When a small amount of Al and La was added in raw materials, they were incorporated in the vitreous coating phase.     

Resolution and signal processing technique of surface charge density measurement with electrostatic probe

When an electrostatic probe is used to measure the surface charge on an insulating plate of constant thickness, the measuring system is regarded a shift-invariant system and the relation between the surface charge density and the probe output can be treated in the spatial frequency domain. The distribution of the surface charge density on an insulating plate just after occurrence of a surface discharge is measured by a Pockels probe, which is regarded as a kind of electrostatic probe without the guard electrode, and restored by Wiener inverse filter. The performance of a Pockels probe and a conventional electrostatic probe are compared quantitatively in terms of the spatial resolution. In the case that the measured object is 3 mm thickness PMMA plate and is charged up to 10 nC/cm/sup 2/ in atmospheric air, it is estimated that the spatial resolution of the Pockels probe with 0.2 mm gap is 1.5 mm and that of the conventional electrostatic probe with the grounded guard electrode with 3 mm gap is 2.2 mm.     

Charge distribution measurement on a truncated cone spacer under DC voltage

A system for measuring charge distribution on an insulating spacer is developed. An electrostatic probe is set close to the spacer, and it moves along its surface maintaining a small gap. The accumulated charge is inversely calculated from the measured data by utilizing the relationship that is obtained through the numerical electric field computation. Using this system, the surface charge distribution on a truncated cone spacer of 80 mm diameter and 15 mm height is measured. The number of measured points is 3402, and the spatial resolution is 3.9 mm. After the application of DC 10 kV for 19 hours, the spacer surface is charged with a spotted pattern. The charge density reaches 60 pC/mm/sup 2/ at its maximum. In addition, the residual charge distribution of partial discharge from metallic particles on the spacer is observed.     

A randomized, double-blind, controlled trial of natural interferon-beta therapy for e-antigen-negative chronic hepatitis B patients with abnormal transaminase levels

Intermittent interferon (IFN) therapy appears to be effective for patients with e-antigen-negative chronic hepatitis B who exhibit abnormal fluctuations of alanine aminotransferase (ALT) levels and histological evidence of disease progression. To determine the optimal dose of IFN in such patients, we studied the effects of natural IFN-beta in a prospective, randomized, double-blind, controlled trial in 36 patients with e-antigen-negative chronic hepatitis B who repeatedly demonstrated abnormal fluctuations in ALT levels. Thirty-six patients were randomly assigned to three groups, receiving doses of: 0.3 MIU IFN (group 1; n = 12), 1 MIU (group 2; n = 12), or 3 MIU (group 3; n = 12), administered twice per week for 24 weeks. Patients were regarded as responders if ALT levels remained within the normal range and HBV-DNA tested negative for 6 months after the initiation of the therapy. According to this criterion, treatment was effective in 16.7% of the patients (2/12) in group 1, 33.3% (4/12) in group 2, and 75% (9/12) in group 3, the efficacy rate in group 3 being significantly higher than that in the other two groups. However, in 12 of the 15 responders, (80%) ALT levels were frequently elevated again within 3 years of the termination of IFN therapy. Although IFN was effective in controlling the manifestations of hepatitis in terms of e-antigen-negative patients who exhibited abnormal fluctuations in ALT, it appears that continuous treatment with intermittent high-dose IFN is necessary to maintain ALT levels within the normal range.     

Emergence and takeover of YMDD motif mutant hepatitis B virus during long-term lamivudine therapy and re-takeover by wild type after cessation of therapy

Treatment of hepatitis B virus (HBV) with lamivudine is effective in suppressing virus replication and results in reduced inflammatory activity. However, the emergence of lamivudine-resistant mutant virus, with amino acid substitution in the YMDD motif of DNA polymerase, has been reported. We report the emergence and takeover of YMDD mutant and re-takeover by wild type during and after long-term lamivudine therapy. YMDD mutants were detected in five patients who showed DNA breakthrough (HBV DNA becoming detectable after a period of DNA negativity), which occurred after 9 to 14 months of lamivudine therapy. Four of five mutants had amino acid sequence YIDD, and the remaining mutant had YVDD. Patients with high HBV-DNA titer and/or hepatitis B e antigen tended to develop breakthrough (P = .038). Using a sensitive and specific polymerase chain reaction (PCR)-based method developed in this study, the emergence of YMDD mutants was detected 1 to 4 months before DNA breakthrough, but not detected in any of the pretreatment sera. The mutants were predominant at breakthrough, but were replaced by wild-type virus 3 to 4 months after cessation of therapy in the two patients who discontinued therapy. One of these patients had a relapse of hepatitis. Mutant continued to replicate in the remaining three patients who continued to receive treatment, and relapse occurred in only one of these patients. Our results suggest that the replication of YMDD mutant viruses is less than wild type and is re-overtaken by wild type after cessation of therapy. Re-administration of lamivudine, possibly combined with other antiviral therapy, might be useful in some patients experiencing hepatitis with lamivudine-resistant variants.     

Relationship of angiographic finding with neovascular structure detected by immunohistochemical staining of alpha-smooth muscle actin in small hepatocellular carcinoma

To elucidate the relationship between angiographic features and histological findings, an immunohistological study of alpha-smooth muscle actin was performed in 106 patients with small hepatocellular carcinoma. Arterial dominance or portal blood paucity were found in 73 patients (68.9%) on digital subtraction angiography, 88 (83.0%) on computerized tomographic arterial portography and 87 (82.1%) on carbon dioxide-enhanced ultrasonography. Among 73 patients with hypervascularity on angiography, 57 (78.1%) had thick-walled, nuclei-rich and slender-shaped vessels (type II), eight (11.0%) had thin-walled, nuclei-poor and oval-shaped vessels (type I) and the remaining eight had a mixed type of II and I. Conversely, among 33 patients without hypervascularity, five (15.2%) had a type II, 21 (63.6%) had a type I, five had a mixed type and two had no positive vessel. Tumour size, histological classification and amount of non-triadal vessels were also associated with the angiographic appearance of the tumours. Among varied aspects of the cancer including tumour size, tumour multiplicity, microscopic portal invasion, histological classification, amount of alpha-smooth muscle actin-positive vessels and shape of alpha-smooth muscle actin-positive vessels, multivariate logistic regression analysis demonstrated that the shape of alpha-smooth muscle actin-positive vessels was solely associated with angiographic hypervascularity independently (P<0.0001). Although the existence of non-triadal vessels characterized hepatocellular carcinoma, angiographic hypervascularity was closely associated with the type II vessel. A morphological change of non-triadal vessel from type I to type II was considered to occur in an early stage of hepatocellular carcinoma.     

Monte Carlo simulation of microparticle motion in vacuum gap

Breakdown voltages of vacuum gaps become lower when the gaps are contaminated by metallic and ceramic microparticles. In this paper, the motion of the microparticles in the gap is simulated using Monte Carlo method in order to evaluate the effect of parameters upon motion and the removal time of the microparticles. As the parameters, we focused on the material of the microparticle, the frequency, the peak value of the applied voltage, the gap length, and the diameter of the lower and upper electrodes. It turned out that the maximum time needed to remove all microparticles could be expressed as multiple regression function. It is suggested that the reliability of the microparticle removal can be increased by spark conditioning with opening/closing operation.     

Effects of cytoplasmic and periplasmic chaperones on secretory production of single-chain Fv antibody in Escherichia coli

The effects of cytoplasmic and periplasmic chaperones on the secretory production of an anti-bovine ribonuclease A single-chain variable fragment (scFv) 3A21 in Escherichia coli were investigated. Co-expression of a cytoplasmic chaperone, GroEL/ES, DnaK/DnaJ/GrpE, trigger factor, or SecB with 3A21 scFv affected the proportions of antigen-binding activity in the cytoplasmic soluble fraction, the periplasmic fraction, and the extracellular medium, but there was no significant difference in the total activity compared to the control without chaperone co-expression. On the other hand, co-expression of a periplasmic chaperone, Skp or FkpA, with the exception of DsbC, greatly increased the binding activity in all the soluble fractions. Co-expression of both Skp and FkpA had no synergistic effect. Combinations of cytoplasmic and periplasmic chaperones decreased the productivity. In shake-flask cultures of cells co-expressing Skp or FkpA, considerable amounts of 3A21 scFv were detected in the extracellular medium by enzyme-linked immunosorbent assay (ELISA) and Western blot, and the extracellular production level of 3A21 scFv was calculated to be around 40mg/l. The binding activity of 3A21 scFv co-expressed with Skp was slightly higher than that with FkpA. These results indicate that the co-expression of periplasmic chaperones Skp and FkpA is extremely useful for the secretory production of scFvs in a culture medium using E. coli, but cytoplasmic chaperones and multiple-chaperone combinations may not be effective.