Thermal properties and crystallization behaviors of medium-chain-length poly(3-hydroxyalkanoate)s

Medium-chain-length poly(3-hydroxyalkanoate)s (mcl-P(3HA)s) with different side-chain length ranging from C3–C9 were synthesized from 2-alkenoic acids of C6–C12 by using a metabolically engineered strain of Escherichia coli. The effect of side-chain length of mcl-P(3HA)s on thermal properties and crystallization behaviors was investigated by DSC and X-ray analyses. All mcl-P(3HA)s formed a chain-packed crystalline structure in the solvent-cast films. Melting temperatures of solvent-cast film of mcl-P(3HA)s first decreased from 59 °C to 45 °C with the change of side-chain from C3 to C4 and thereafter increased to 69 °C with an extension of side-chain to C9. The X-ray diffraction patterns indicate the formation of a layered structure aligned the main-chains in planes involving side-by-side packing of side-chains with a periodic distance of 1.6–2.8 nm for the mcl-P(3HA)s with over C4 side-chain. The interlayer distance increased proportionally to the length of side-chain for the mcl-P(3HA)s with over C4 side-chain, while the corresponding value of mcl-P(3HA) with C3 side-chain was apparently deviated from the extrapolated line plotted the distance against side-chain length. These results indicate that the changeover in crystallization manner occurs between P(3HA)s with under C3 side-chain and with over C4 side-chain. For the mcl-P(3HA)s with side-chain carbon number over C7, two distinct phase transitions were happened during heating process from a melt-quenched amorphous state. At lower temperature region, the mcl-P(3HA) molecules formed a smectic liquid-crystalline structure owing to the side-chain interactions, and the structure was disrupted at temperatures between 20 and 50 °C. After the disruption of smectic aggregates, the crystallization of mcl-P(3HA) chains immediately occurred with participation of both main- and side-chains.     

A case of synchronous triple early cancer occurring in the stomach, colon and gallbladder

Tissue expansion is one of the most important armamentaria for aesthetic scalp reconstruction after burn; however, the proper way to employ this technique for the scalp reconstruction usually presents a challenge to the plastic surgeon, especially in the case of a "sideburn" scenario or a large lesion, as with, for example, hemiscalp alopecia. In this article, 11 patients, with different degrees of hair-bearing scalp loss as a result of burn, and including four patients with hemiscalp alopecia were successfully treated by using tissue expansion. The results show that tissue expansion is a simple, safe, and efficient technique for aesthetic scalp reconstruction. Versatile design of the expanded scalp flap can distribute the expanded hair-bearing scalp properly in the reconstructed recipient site.     

PD signal propagation characteristics in GIS and its locationsystem by frequency components comparison

Propagation characteristics of partial discharge signal in GIS were investigated in a laboratory and at a 300 kV underground substation. The laboratory test indicates that signal damping can be attributed to two major mechanisms; reflection due to irregularity of characteristic impedance such as spacers, and the mode shift from TEM to TE or TM. Tests at the substation show that the signal damping phenomena are independent of propagation direction, and the mode shift gives rise to a large signal damping. The major higher mode seems to be TE₁₁ . Amplitudes of observed waveforms using narrow-band filters that agree well with the corresponding frequency components observed with a spectrum analyzer show irregular or random behavior depending upon their observation point. This indicates that narrow-band filters do not seem to be suitable for a partial discharge location system by a frequency component comparison, and the realizability of the system using broadband filters instead is discussed     

Development of a novel method for feeding a mixture of -lactic acid and acetic acid in fed-batch culture of Ralstonia eutropha for poly- -3-hydroxybutyrate production

Fermentative production of poly- -3-hydroxybutyrate [P(3HB)] from a mixture of -lactic acid and acetic acid by Ralstonia eutropha was investigated. For fed-batch culture with cell density, it is necessary to control the concentration of these organic acids in the culture medium below the inhibitory level for cell growth. Therefore, a novel feeding method, termed the computer-controlled pH-stat substrate feeding method, was developed using the rate of increase of the pH (pH-increasing rate) of the culture medium as an indicator for feed control. The pH-increasing rate, which was calculated every minute by a pH meter-linked computer, represented secondary information regarding substrate consumption by cells. When the pH-increasing rate decreased to 5% of the maximum increasing rate, acidic substrate solution was fed into the fermentor until the pH was reduced to 7.00. Using this feeding strategy, the cell concentration and PHA content obtained in 42 h were 75.0 g/l and 73.1% (w/w), respectively, resulting in a high P(3HB) productivity of 1.30 g/l·h.     

Production of new antioxidant compound from mycosporine-like amino acid,porphyra-334 by heat treatment

In this study, we evaluated the antioxidant activity (diphenylpicrylhydrazyl (DPPH)-radical scavenging activity) of the low-molecular weight fraction of water-soluble Susabinori (Porphyra yezoensis) extract (LMF). DPPH-radical scavenging activity of LMF (65.5 μmol-Trolox eq/ml) was enhanced at temperatures over 100 °C (1.4, 2.0 and 2.4 times higher at 100, 110 and 120 °C, respectively). As a result of HPLC separations, a newly produced peak was observed in heat treated LMF, while a marked decrease of another peak was found after heat treatment of LMF. The decreased peak was identified as porphyra-334, which is a typical mycosporine-like amino acid, by ESI/MSⁿ analysis (protonated molecule [M + H]⁺ at m/z 347.1 and its fragment ion 303.1). The newly produced compound with [M + H]⁺ at m/z 329.1 was found to be a dehydrated compound of porhyra-334. The compound exhibited an extremely high-IC₅₀ value of 10.1 μg/ml in DPPH-radical scavenging activity, compared to porphyra-334 (>1000 μg/ml).