Evaluation of vertical cell fluidity in a multilayered sheet of skeletal myoblasts

The procedure for fabricating a multilayered cell sheet has been developed by combining multiple sheets using a thermo-responsive surface and stamp system. Confocal laser scanning microscopy revealed that the fluidity of a multilayered sheet of skeletal myoblasts could be estimated as vertical diffusivity and changed upon addition of dermal fibroblasts.     

Thermal deterioration diagnosis by optical fiber sensors formica-epoxy insulation of HV induction motors

Optical diagnosis for aged mica-epoxy insulation of HV (3.0 to 6.6 kV), enclosed induction motors used in compressors has been studied. The developed optical fiber sensor consists of two optical fiber cables (one for light transmission, the other for light reception; each ~3 m long), two types of laser diodes as light sources, and an optical power meter as a detector. It was used to measure the change ΔA_R in the reflective absorbance of insulation at two wavelengths for model pieces and samples obtained from three aged induction motors. This optical sensor could detect only deterioration on the surface layer as a ΔA_R change, and thus deterioration of the inner layer was evaluated by the peak temperature of tan δ (T_g,DMA) in dynamic mechanical analysis (DMA). The T_g,DMA of insulation is one of the most important parameters which can be used to evaluate material lifetimes, because it relates to elasticity. The ΔA_R correlated with the T_g,DMA of DMA, and the correlation coefficient of an accelerated experiment using model pieces was ~0.79. Thus, this optical diagnosis can be applied to evaluate the deterioration of mica-epoxy insulation of HV induction motors. The extent of insulation deterioration can be calculated quantitatively using the diagnostic master curve, which is obtained from accelerated heating experiments based on chemical kinetics     

Blood compatibility and filtration characteristics of a newly developed polyester polymer alloy membrane

Background: Many synthetic polymeric membranes have been widely used for blood purification therapies for removing larger solutes and for better blood compatibility. Methods: Five different filters with polyester polymer alloy (PEPA) membrane (Nikkiso) that included polyvinylpyrrolidone (PVP), that is, standard‐pore‐size FLX (PEPA with PVP(–)), standard‐pore‐size FDX (PEPA with PVP(+)), new FDX (PEPA with PVP(++)), larger‐pore‐size FDY (PEPA with PVP(+)), and new FDY (PEPA with PVP(++)), were evaluated in terms of in vivo blood compatibility and aqueous in vitro sieving coefficient (s.c.) for albumin. Results: FDY showed excellent small changes in C3a concentration during the treatment right after switching from polysulfone membrane, leaving no significant changes in other blood‐compatible indices. New FDY, in contrast, showed less biocompatible characteristics in terms of C3a, which may be caused by increased use of PVP. FLX (no PVP) showed the highest s.c. for albumin. With a hydrophilic agent (PVP), the s.c. was greatly reduced in FDX. By enlarging the pore diameter in FDY, the s.c. increased in accordance with the enlargement. Generally speaking, polysulfone filters with PVP(+++) reach the peak s.c. value approximately 10 min after starting the experiment. The s.c. of the PEPA membrane with no or small amount of PVP, which showed excellent blood compatibility, never showed peaks, whereas the peak s.c. values were found in new PEPA with increased amount of PVP that showed higher C3a changes. Conclusions: The separation characteristics of aqueous albumin may be related to its blood compatibility.     

Mechanism of reduction of dinitrogen monoxide by carbon monoxide over magnesium oxide—role of surface formate species [1]

With the help of infrared spectroscopy and the transient response method, it was revealed that surface formate species were involved in the title reaction over magnesium oxide. This contrasted to the results obtained over reducible metal oxides on which the catalyst redox was operating.     

Caffeine abolishes the ultraviolet-induced REV3 translesion replication pathway in mouse cells

When a replicative DNA polymerase stalls upon encountering a photoproduct on the template strand, it is relieved by other low-processivity polymerase(s), which insert nucleotide(s) opposite the lesion. Using an alkaline sucrose density gradient sedimentation technique, we previously classified this process termed UV-induced translesion replication (UV-TLS) into two types. In human cancer cells or xeroderma pigmentosum variant (XP-V) cells, UV-TLS was inhibited by caffeine or proteasome inhibitors. However, in normal human cells, the process was insensitive to these reagents. Reportedly, in yeast or mammalian cells, REV3 protein (a catalytic subunit of DNA polymerase ζ) is predominantly involved in the former type of TLS. Here, we studied UV-TLS in fibroblasts derived from the Rev3-knockout mouse embryo (Rev3KO-MEF). In the wild-type MEF, UV-TLS was slow (similar to that of human cancer cells or XP-V cells), and was abolished by caffeine or MG-262. In 2 cell lines of Rev3KO-MEF (Rev3(-/-)p53(-/-)), UV-TLS was not observed. In p53KO-MEF, which is a strict control for Rev3KO-MEF, the UV-TLS response was similar to that of the wild-type. Introduction of the Rev3 expression plasmid into Rev3KO-MEF restored the UV-TLS response in selected stable transformants. In some transformants, viability to UV was the same as that in the wild-type, and the death rate was increased by caffeine. Our findings indicate that REV3 is predominantly involved in UV-TLS in mouse cells, and that the REV3 translesion pathway is suppressed by caffeine or proteasome inhibitors.     

Seminatural Occurrence of Fullerenes

In continuation to our search of fullerenes in usual soots, sixteen additional samples of Chinese ink stick have been analyzed by HPLC. When combined with our previous results, we recognize that C₆₀-content in Chinese ink sticks decreases with time following the first order rate law. This novel observation was interpreted in terms of diffusion-dissipation of C₆₀ molecules through the solid stick.     

Preparation and thermo‐mechanical properties of heat‐resistant epoxy/silica hybrid materials

Diglycidyl ether of bisphenol‐A (DGEBA) based epoxy/silica hybrid materials filled with various amounts of 3‐glycidoxypropyltrimethoxysilane (GPTMS) and silica nanoparticles were prepared, using 4,4′‐diaminodiphenyl sulfone (DDS) as curing agent. The obtained hybrid materials were analyzed by means of Fourier‐transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated that the introduction of GPTMS and silica nanoparticles had synergistic effect. The addition of GPTMS not only ameliorated the compatibility between silica and the epoxy matrix but also increased the crosslinking density of the epoxy system; meanwhile the nano‐silica further reinforced the inorganic network of the hybrid system. Consequently, the hybrid materials showed much improved heat‐resistant properties. The storage modulus of the hybrid systems showed no obvious decrement in the glass transition region and kept at a high value even in the temperature region up to 300°C. The integral thermal stability of the resulting hybrid materials was also improved compared with the corresponding pure epoxy resin. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.     

Analysis of the correlation between optical transmission loss and weight loss of thermally deteriorated epoxy resins using near infrared spectroscopy

The correlation between the optical transmission loss and the weight loss of thermally deteriorated epoxy resins was analyzed using near infrared (NIR) spectroscopy. Using three types of acid anhydride cured epoxy resins, the optical transmission losses at 850 nm of each resin and their weight losses were measured during the accelerated heating tests. At longer heating times the color of each resin darkens and its weight decreases, i.e., the values of the optical transmission loss and the weight loss are both increasing gradually. Both of tendencies are similar in magnitude, and the optical transmission loss of each resin has a good correlation with its weight loss. It is postulated that the cross‐linking was increased in the resin by the thermal oxidation reaction, and that the simultaneous elimination reaction occurs from the surface. As the thermally oxidized structure is more conjugated, the optical transmission loss is increased in the shorter wavelength region, and thus theoretically, one can predict the weight loss of the thermally deteriorated epoxy resins non‐destructively by measuring the optical transmission loss using NIR. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 14–19, 2000     

Structures of H3PO4/SiO2 catalysts and catalytic performance in the hydration of ethene

The hydration of ethene was carried out over H₃PO₄/SiO₂ having various amounts of H₃PO₄. The rate of the ethanol formation increased markedly with the increasing H₃PO₄ loadings, in particular above 60–70 wt%. By X-ray diffraction (XRD), and

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MAS NMR methods, it was revealed that various silicon phosphates were produced in the preparation of the catalysts. The structures of the phosphates depended on the H₃PO₄ loadings. It was suggested that Si(HPO₄)₂·H₂O species which formed at higher H₃PO₄ loadings were hydrolyzed to H₃PO₄ and SiO₂ during the course of the reaction, yielding the catalysts with high performance. The bulk phase of the H₃PO₄ was involved in the reaction.