Creepage discharge characteristics over solid-liquid interfaceswith grounded side electrode

The properties of streamers traveling over the surface of oil-immersed solid dielectrics were experimentally studied under lightning impulse conditions. Streamer polarity and the position of a grounded side electrode significantly affected the relationship between the streamer extension length and the applied voltage. Solid surface charging also had a large effect on the streamer propagation. However, the streamer propagation properties showed a consistent dependence on the potential at the solid-liquid interfaces. In addition, the potential drop inside the streamer channel was measured as a function of normalized streamer length. The curve revealed that the potential drop increased drastically within the region of ~20% from the streamer tip. The streamer appeared to progress with a constant mean velocity     

Electronic state of κ-(BMDT-TTF)2Au(CN)2 studied by NMR and thermoelectric measurements

The electronic state of κ-(BMDT-TTF)₂Au(CN)₂ was investigated by measurements of H-NMR¹-NMR and thermoelectric power. In H-NMR,¹-NMR, the profile of the nuclear relaxation curve changed drastically at 75 K from exponential time-dependence to non-single exponential one reflecting inhomogeneous relaxation. This change evidences a transition in the electronic state at this temperature. However, the longest T₁ below the transition temperature behaves like a Korringa law, suggesting that the low-temperature state is another metallic state. The thermoelectric power shows a strong anomaly around 75 K, being consistent with the NMR results. Above that, the temperature dependence is similar to that found in the κ phase of BEDT-TTF compounds, suggesting a similar Fermi-surface topology. These results suggest that the transition at 75 K is not a conventional metal-to-insulator transition but a metal-to-metal transition.     

hiPSC-Derived Cardiac Tissue for Disease Modeling and Drug Discovery

Relevant, predictive normal, or disease model systems are of vital importance for drug development. The difference between nonhuman models and humans could contribute to clinical trial failures despite ideal nonhuman results. As a potential substitute for animal models, human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) provide a powerful tool for drug toxicity screening, modeling cardiovascular diseases, and drug discovery. Here, we review recent hiPSC-CM disease models and discuss the features of hiPSC-CMs, including subtype and maturation and the tissue engineering technologies for drug assessment. Updates from the international multisite collaborators/administrations for development of novel drug discovery paradigms are also summarized.     

Comparative studies on the fatty acid composition of moderately and extremely thermophilic bacteria

The fatty acids of three strains of extremely thermophilic bacteria and three strains of moderately thermophilic bacteria were examined by gas liquid chromatography. All the thermophiles contained straight, iso, and ante-iso branched fatty acids. Iso C_17∶0 acid was abundant in both the moderately thermophilic strains (10–33%) and the extremely thermophilic strains (50–61%). The pair of fatty acids iso C_15∶0 and iso C_17∶0 was the predominant pair in both the moderately (34–64%) and extremely (76–87%) thermophilic strains. The pair of fatty acids ante-iso C_15∶0 and ante-iso C_17∶0 was present in larger amount in moderately (25–34%) than in extremely (8.5–15%) thermophilic strains. No hydroxy cyclopropane, or unsaturated fatty acids were found. One extreme thermophile,Flavobacterium thermophilum HB-8 was grown at 6 different culture temperatures from 49–82 C, and the changes of its fatty acid composition were studied. The ratios of iso C_17∶0/iso C_15∶0 and ante-iso C_17∶0/ante-iso C_15∶0 were much greater at higher culture temperatures, indicating chain elongation.     

Optical properties of dye-doped deoxyribonucleic acid films

Dye-doped deoxyribonucleic acid–surfactant films have been prepared by an intercalation method and their optical properties have been investigated. Coumarin 1 (C1), known as a neutral laser dye, can be successfully incorporated in deoxyribonucleic acid-surfactant films by immersing them in aqueous dye solution. About 6 wt% C1 can be doped in samples when the immersion time is 86400 s. C1-doped samples show pronounced optical absorption and photoluminescence bands. Not only hydrophobic–hydrophobic interactions but also molecular structures of dyes play prominent roles in the formation of neutral dye-doped deoxyribonucleic acid-surfactant films. It is surmised that C1 stays inside the double helix of deoxyribonucleic acid (DNA) and/or between the alkyl groups of surfactants.     

Influence of morphology on photo‐degradation of low density polyethylene films

The effect of the morphology on photo‐degradation was investigated for low‐density polyethylene materials. For this purpose, films with different degrees of crystallinity and different degrees of orientation were prepared. For all the films, photodegradation was promoted at 336K for 12 days using a weather meter. The following results were obtained. There existed an induction period before degradation or chain scission. The induction period was longer for stretched films than for un‐stretched ones. Also, the rate of degradation became lower for stretched films. However, both the induction period and the rate of degradation hardly changed with heat‐treatment condition, that is, the degree of crystallinity. In the induction period, the density changed in a complicated manner. This complicated change must be due to the change in the molecular aggregation state of the amorphous phase. The rheological and GPC measurements indicated that photo‐degradation causes the lowering of molecular weight and the increase in higher molecular weight fraction, and consequently the broadening of molecular weight distribution. The lowering of molecular weight may be caused by chain scission and the increase in higher molecular weight fraction by the formation of crosslinks.     

A monomeric human C4b-binding protein (C4bp) more efficiently inactivates C3b than natural C4bp: participation of C-terminal domains in factor I-cofactor activity

We designed a cDNA construct encoding an artificial membrane molecule consisting of all 8 short consensus repeats (SCRs) of human monomeric C4b-binding protein (C4bp) followed by DAF's GPI anchor, named mC4bp, and expressed the protein on swine endothelial cells (SEC). At the same level of expression, mC4bp protected host cells as effectively as DAF, the most potent complement (C) regulator on the membrane. This result was unexpected from the reported functional properties of natural multimeric C4bp. Here, we investigated the mechanism whereby mC4bp has potent cell-protective activity. Our results were as follows: (1) mC4bp serves more efficiently as a methylamine-treated C3 (C3ma)-inactivating factor I-cofactor than natural C4bp and as efficiently as MCP as a methylamine-treated (C4ma)-inactivating cofactor by fluid-phase cofactor assay: (2) the potency of C3ma inactivation by mC4bp and factor I is quite high compared to those of other cofactors: (3)blocking studies using mAbs against C4bp suggested that both the 48 kDa N-terminal fragment and the C-terminal domain near the portion responsible for bundle formation participate in the high C3ma-inactivating capacity of mC4bp. Thus, acquiring high C3ma-inactivating capacity secondary to monomeric alteration leads to high C regulatory activity of mC4bp. These results infer that mC4bp differs from C4bp in its potent factor I-cofactor activity and is a good candidate as a safeguard against hyperacute rejection of xenografts.     

The inhibitory effect of noradrenaline on thyrotrophin-stimulated 3,5,3''-tri-iodothyronine and thyroxine release is mediated through a Ca(2+)-dependent process in the thyroid gland of the mouse

We characterized the cell-free activating system of the superoxide (O2-)-producing NADPH oxidase of pig neutrophils. Activation of the oxidase required both the membrane and cytosolic fractions in the presence of sodium dodecyl sulfate. Chromatography on 2',5'-ADP-Sepharose resulted in separation of the cytosolic fraction into two fractions, the flow-through and bound fractions, which synergistically supported the O2- production with the membrane fraction in the absence of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), whereas only the bound fraction besides the membrane fraction was required for the activation in the presence of GTP gamma S. The effective factors in the bound fraction were further purified by gel filtration on Superdex G-200 and anion exchange chromatography on Mono Q and found to be p47-phox and p63-phox. The purified recombinant p47-phox and p65-phox replaced corresponding native factors for the activation. These results suggest that the membrane fraction from pig neutrophils contains the GTP-binding protein responsible for the activation. Furthermore, the presence of the GTP-binding protein for the activation in the flow-through fraction from 2',5'-ADP-Sepharose was also shown on the basis of the findings that extensive dialysis of the flow-through fraction resulted in complete loss of the ability to activate the oxidase with the recombinant factors and the washed membrane of human neutrophils which contained no GTP-binding protein for the activation and the lost ability was recovered by the addition of GTP gamma S. Thus, activation of the oxidase in the cell-free system of pig neutrophils absolutely requires the GTP-binding protein which localizes in the membrane fraction or in the cytosolic fraction.     

Broad-band GaAs monolithic equalizing amplifiers formultigigabit-per-second optical receivers

The authors discuss the development of ICs (integrated circuits) for a preamplifier, a gain-controllable amplifier, and main amplifiers with and without a three-way divider for multigigabit-per-second optical receivers using a single-ended parallel feedback circuit, two (inductor and capacitor) peaking techniques, and advanced GaAs process technology. An optical front-end circuit consisting of a GaAs preamplifier and an InGaAs p-i-n photodiode achieves a 3-dB bandwidth of 7 GHz and -12-dBm sensitivity at 10 Gb/s. Moreover, a gain-controllable amplifier obtains a maximum gain of 15 dB, a gain dynamic range of 25 dB, and a 3-dB bandwidth of 6.1 GHz by controlling the source bias of the common-source circuit. Gain, 3-dB bandwidth, and output power of the main amplifier with the three-way divider are 17.4 dB, 5.2 GHz, and 5 dBm, respectively. These ICs can be applied to optical receivers transmitting NRZ signals in excess of 7 Gb/s     

Tocopherol and fluorescence levels in deep-frying oil and their measurement for oil assessment

This study examined how tocopherol retention is affected by the presence or absence of food coatings, and also tested the measurement of fluorescent substance levels in cooking oil to evaluate oil deterioration. Potato slices were tempura-fried (with a coating) or french-fried (without a coating). The three tocopherol isomers decreased with heating time, and better retention was found in the tempura process. The decomposition rates of tocopherol were in the order γ> δ ≥α for the three isomers for both processes over repeated fryings. The fluorescence of frying oil increased 15-and 17-fold after tempura-and french-frying, respectively, for 32 consecutive times. Changes in the amounts of tocopherol and the fluorescence correlated well with the changes found by the chemiluminescent intensity and five conventional methods of oil quality measurement. These results indicated that tocopherol retention is affected by the food coating, and that measurements of vitamin E loss and fluorescence increase in oil should be useful for assessing the progressive deterioration of frying oil with its repeated usage.