Effects of C60, a Fullerene, on the Activities of Glutathione S-Transferase and Glutathione-Related Enzymes in Rodent and Human Livers

The effects of C₆₀, a fullerene, on the activities of glutathione 5-transferase (GST), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) in rodent and human livers were investigated. the GST activity in rat liver towards frans-4-phenyl-3-buten-2-one and that in mouse liver towards ethacrynic acid were inhibited by C₆₀- the GST activity towards 1,2-dichloro-4-nitrobenzene, isomerase activity of GST towards androst-5-ene-3,17-dione, GSH-Px activity and GR activity were not affected by C₆₀ a kinetic study using purified mouse GST-π with ethacrynic acid (25-100 μM) as the substrate revealed that C₆₀ was a non-competitive inhibitor of the enzyme with a K_i = 48.8 ± 0.25 μM and a K_i = 47.9 ±0.18 μM. However, C₆₀ did not inhibit the activity of purified mouse GST-π towards l-chloro-2,4-dinitrobenzene. Thus, the inhibition by C₆₀ appears to be substrate-specific. In human liver, C₆₀ inhibited the GST activity towards ethacrynic acid, and moderately inhibited GSH-Px and GR activities.     

Surface properties of LB monolayers composed of aminimide derivatives having two alkyl chains

Langmuir-Blodgett monolayers were prepared using a series of aminimide derivatives having two alkyl chains. One of the alkyl chains had 19 carbons, while the number of the other alkyl chain was systematically changed from 8 to 20. Molecular organization of the aminimides on the water surface reflected the length of alkyl chains. Inter-chain packing and conformational order of the alkyl chains in the monolayer were affected by the length of the two alkyl chains. Steric and dynamic contact angles of a series of aprotic liquid having low surface tension were measured to investigate surface properties of the films with varying molecular organization of alkyl tail groups. Fluid-like monolayers having molecularly rough surface indicated high wettabilities for both of n-alkanes and naphthalene derivatives. However, contact angle hyteresis on the monolayer was sensitive to the sort of probe liquids owing to the interaction between the uppermost portion of the alkyl chains aligned homeotropically on the fluid-like monolayers. In contrast, the monolayer containing well-ordered, well-packed alkyl chains indicated low wettabilities, small hysteresis and random orientation of liquid crystals.     

Preparation of Li2B4O7 Films with Preferential Orientation by Sol–Gel Method

Li₂B₄O₇ films, a promising material for surface acoustic wave devices, were prepared by the sol—gel method using metal alkoxide precursors as starting materials. The Li₂B₄O₇ films on silicon (100) and (111) single crystals prepared from a coating solution to which acetic or hydrochloric acid was added were highly oriented along the (122) plane, whereas those without acid additive were randomly oriented. The results were interpreted based on the basic sol-gel chemistry and the lattice matching between the film and substrate.     

Molecular weight distribution of the methyl methacrylate (MMA) polymer separated from the MMA-grafted silk fiber

The molecular weight distribution of poly-methyl methacrylate (poly-MMA) chains separated from MMA-grafted silk fibers obtained by using potassium persulfate (KPS) and tri-n-butylborane (TBB) as initiator of the graft-copolymerization reaction have been examined by gel permeation chromatography (GPC). GPC elution pattern of poly-MMA chains shows a bimodal molecular weight distribution. The two peaks have been identified as heavy and light component. The average molecular weight of the heavy component ranges from 48.5 to 200 kD for poly-MMA copolymerized by the KPS reaction system and from 336 to 816 kD for the poly-MMA copolymerized by the TBB reaction system. The light component has an average molecular weight lower than 1,000 D and its value is almost similar in all the samples examined. Scanning electron microscopy (SEM) analysis revealed the presence of MMA oligomers formed on the fiber surface during grafting. The molar ratio between poly-MMA chains and silk fibroin attains a constant value that seems to be specific for a certain reaction system. A linear correlation has been observed between the weight gain and the average molecular weight of the poly-MMA chains. These findings suggest the effect of grafting parameters on the molecular weight and molecular weight distribution of the grafted polymer, as well as its influence on the physical properties and textile performances of MMA-grafted silk fibers.     

The crystal structure of thermostable mutants of chimeric 3-isopropylmalate dehydrogenase, 2T2M6T

A chimeric 3-isopropylmalate dehydrogenase (IPMDH), 2T2M6T,was produced by replacing the amino acid sequences of the Thermusthermophilus enzyme with those of the Bacillus subtilis enzymefrom residues 75 to 113. Decreased thermostability of the chiaiericenzyme was recovered by either evolutionary engineering (I93L)or site-directed mutagenesis (S82R). The 3-D structures of themutants have been determined by X-ray diffraction at 2.1 Åresolution. Although S82R was refined routinely, (I93L) requiredthe preliminary rigid-body refinement of each domain. The X-factorswere reduced to 0.18 for both mutants. Removal of the unfavorabletorsion angle at isoleucine 93 may have made I93L more thermostablethan 2T2M6T. In the case of S82R, the replaced arginine residuecontributed to the extra hydrogen bond with water molecules.The large replaced residue decreased the entropy of the solvent,which may have caused the improvement in enzyme thermostability.Denatu ration by heating may be interpreted from these structuralresults.     

Effect of preparation conditions on the characteristics of exfoliated graphite

Exfoliated graphite (EG) was prepared from graphite intercalation compounds (GICs) synthesized electrochemically with different electricity consumption from 10.83 to 40.00 A h/kg. Effects of electricity consumption on the synthesis of GICs and of exfoliation temperature on different parameters of EG, i.e. exfoliation volume, volatile content, specific surface area and pore volume measured by mercury porosimetry, length and width of worm-like particles, and distance between neighboring balloons based on the zigzag model for worm-like particles of EG, were studied. These parameters were found to depend strongly on the electricity consumption and also on exfoliation temperature. Exfoliation volume, volatile content, specific surface area and pore volume on EG prepared at 1000 °C increased with increasing electricity consumption, but the distance between neighboring balloons was found to decrease. These results reveal marked development of pores in EG samples. Raising exfoliation temperature increased exfoliation volume, specific surface area and pore volume up to 800 °C. Above this temperature these parameters tended to be stable.     

Copper ⇌ Alkali Ion Exchange of Alkali Aluminosilicate Glasses in Copper-Containing Molten Salt: II, Divalent Copper Salts, CuCl2 and CuSO4

The ion-exchange mechanism between copper and alkali ions, when 20R₂O · 10Al₂O₃· 70SiO₂ (R = Li, Na, and K) glasses are immersed in divalent copper-containing molten salts in air and nitrogen at 550°C, has been investigated. In molten CuCl₂, the ion-exchange behavior in both air and nitrogen was very close to that in molten CuCl in air reported previously. This is explained by assuming that CuCl₂ decomposes into CuCl and Cl₂ at 550°C and the Cu⁺ ions thus formed mainly diffuse in glasses to replace alkali ions, where Cl₂ acts as an oxidizing agent just like oxygen. In the case of molten CuSO₄─₂SO₄, a small amount of Cu⁺ which is present in the molten state plays a primary role in the Cu ⇌ R⁺ ion exchange process, although the contribution of direct Cu²⁺⇌ 2R⁺ ion exchange cannot be ignored.     

A memory‐in‐pixel reflective‐type LCD using newly designed system and pixel structure

A 7.03‐in. extended graphics array reflective LCD prototype has been developed by using memory‐in‐pixel (MIP) technologies with a newly designed system and pixel structure. The MIP system comprising a MIP backplane and a display driver has been optimized to reduce power consumption. The MIP backplane has specific circuits that allow accessing row drivers randomly, and the display driver manages which row should be accessed. Thus, the system is capable of showing a mixture of still and moving images, resulting in low power consumption. A dithering block embedded in the display driver enables to select an appropriate dithering algorithm according to the types of images and the position on the screen. In addition, the novel pixel structure, “three divided patterns”, has been designed to improve image quality and to provide visibility in dark environments. The latter is based on a novel approach; interpixel area is used for an aperture to transmit light from the backlight, and the fringe field from adjacent pixel electrodes is used to control LC directions. The feature of the pixel structure is also effective for obtaining equivalent gamma between reflective and transmissive images.     

Electrical Properties of Nonconventional Bi-Ba-Cu-O Glasses

Electrical properties of Bi-Ba-Cu-O glasses have been systematically investigated, and possible conduction mechanisms are discussed. Conductivity behavior is described by a small-polaron hopping mechanism. log σ_o, the slope of the log σ- W straight line, and the magnitude of the polaron bandwidth reveal that adiabatic hopping is dominant in the glasses. The Seebeck coefficient, S , of the Bi₁₆BaCu₃O_y glass is positive, indicating that the glass is a p -type hole conductor. The positive deviation of the observed S value from the theoretical S value is explained by assuming that the only oxygens bonded to both Cu²⁺ and Cu⁺ ions mediate indirect Cu⁺-O-Cu²⁺ hopping.