16S rRNA pyrosequencing-based investigation of the bacterial community in nukadoko, a pickling bed of fermented rice bran

Nukadoko is a naturally fermented rice bran mash traditionally used for pickling vegetables in Japan; its refreshment and fermentation cycles sometimes continue for many years. Here, we investigated the structure and dynamics of the bacterial community in nukadoko by conducting pyrosequencing and quantitative polymerase chain reaction (PCR) analyses of 16S ribosomal RNA genes (rDNA). Of the 16 different samples studied, 13 showed Lactobacillus-dominated microbiota, suggesting that aged nukadoko samples tend to realize a niche, favorable Lactobacillus species. The lactic acid bacterial community of each of the 16 samples was classified into 3 types according to the presence or absence of 2 predominant species, Lactobacillus namurensis and Lactobacillus acetotolerans. The dynamics of the bacterial community during fermentation and the subsequent ripening process were examined using a laboratory model of nukadoko inoculated with an aged nukadoko sample (inoculated model). Lb. namurensis grew rapidly in the first 2 days, accompanied with a rapid decrease in pH and an increase in lactate levels, while Lb. acetotolerans grew with a longer doubling time and slow acidification during the 20 days after inoculation. On the other hand, spontaneous fermentation of the nukadoko model prepared from fresh rice bran without the nukadoko inoculation (inoculant-free model), showed the growth of some non-Lactobacillus species such as staphylococci and bacilli within the first 10 days; thereafter, Lb. namurensis was dominant, while Lb. acetotolerans was not detected during the 20-day experimental period. These results suggest that the naturally established Lactobacillus community in aged nukadoko is effectively involved in the biocontrol of the microbial community of nukadoko during the refreshment and fermentation cycles.     

Evaluation of hydrogen-assisted cracking behavior of low-alloy steel in the range 95 °C to 350 °C

In this report, hydrogen-assisted cracking (HAC) behavior of low-alloy steel was evaluated using a constant elongation rate tensile test, and the temperature and crack tip strain rate effects were observed. It was found that temperature dependence of the threshold condition (C _σm ^c ) of HAC above about 100 °C followed the relation C _σm ^c = Kexp(−41,300/Rr) whereK is a constant andT is absolute temperature. The relationship between HAC growth rate and crack tip strain rate was established as almost linear, irrespective of temperature and hydrogen concentration at the crack tip. Hydrogen heat release tests were also performed. From these tests, formation and growth of microcracks which are trap sites of hydrogen were thought to be the mechanism of HAC in the steel. From this mechanism, HAC behavior of the low-alloy steel could be qualitatively explained.     

Improvement of diamond X-ray mask membrane: Optical transmittance, surface roughness and irradiation durability

A viable method for the improvement of the polycrystalline diamond X-ray mask membrane is proposed. The use of an ionized cluster beam yields the smoothest surface. Sol-gel planarization film coating with indium tin oxide is the most effective method for obtaining high optical transmittance without sacrificing high synchrotron irradiation durability.     

Electron Spin Resonance of High-Spin Co2+ in Alkali Borate and Alkali Germanate Glasses

Electron spin resonance spectra of high-spin Co²⁺ doped in alkali borate and alkali germanate glasses have been measured at 4.2 K. For comparison, the corresponding spectrum in a 33K₂O·67SiO₂ glass has also been measured. On the basis of the spectral line shape, the observed spectra, together with those in the literature, seem to be classified into four spectral types that represent Co²⁺ ions in octahedral coordination, a mixture of some types of coordination, tetrahedral coordination with nearly axial symmetry, and distorted tetrahedral coordination.     

Operating characteristics of a superconducting fault current limiting transformer (SFCLT) and enhancement of electric power system stability

We have been investigating the feasibility of a superconducting fault current limiting transformer (SFCLT) with the functions of fault current suppression and system stability improvement. This paper discusses these functions with consideration of overvoltage and thermal characteristics of SFCLT, and their dependence on recovery time into superconducting state after the quench of SFCLT. Simulation results using EMTP suggested that SFCLT would be coordinated with the background power system under the appropriate superconducting recovery time. The operating parameters of SFCLT were also optimized in a simplified power transmission model system. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(2): 40–47, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10070     

纺丝及纤维成形的机理(V)

本文以等规聚丙烯为例,继上期学报对熔体纺丝过程的讨论之后,对熔体纺丝纤维的拉伸加工过程中,纤维结构和性能的变化进行了深入的阐述和分析,并根据纺丝的基础方程式介绍了数学模拟的方法。     

Intracellular proteolytic cleavage of 9-cis-retinoic acid receptor alpha by cathepsin L-type protease is a potential mechanism for modulating thyroid hormone action

We previously reported that the responsiveness of hepatocytes to thyroid hormone is markedly attenuated when they were cultured as monolayers rather than spheroids. To elucidate the mechanisms underlying the altered responsiveness, thyroid hormone receptor auxiliary proteins in the hepatocytes were analyzed by electrophoretic mobility shift assay. The major thyroid hormone receptor auxiliary protein was identified as 9-cis-retinoic acid receptor alpha (RXRalpha) in the hepatocytes regardless of the culture conditions. The cytoplasmic fraction was shown to contain a protease(s) that cleaves RXRalpha at its amino terminus. The presence of the protease in the cytosol, but not in the nucleus, was ascertained by incubating full-length 35S-labeled RXRalpha with each fraction. Using various protease inhibitors, it was shown that cathepsin L-type protease could participate in the cleavage of the RXRalpha. The enzyme activity was much higher in the monolayers than the spheroids. Inhibition of this enzyme activity in the monolayer hepatocyte resulted in the increase of nuclear RXRalpha protein and the augmentation of T3-dependent induction of spot 14 mRNA. These results suggest that the changes in cathepsin L-type protease activity in the cytosol may alter the turnover of RXRalpha in the nucleus and modify the function of steroid receptor superfamilies that heterodimerize with RXRalpha.     

Preoperative evaluation of hepatic functional reserve following hepatectomy by technetium-99m galactosyl human serum albumin liver scintigraphy and computed tomography

It is extremely important to have a good grasp of the acceptable limit of hepatectomy before operation because postoperative liver failure can take a fatal course; however, baseline data on the limit of hepatectomy have not been clearly defined. We therefore evaluated and compared the predicted remnant liver function obtained by computed tomography(CT) and technetium-99m diethylenetriamine penta-acetic acid-galactosyl human serum albumin (99mTc-GSA) liver scintigraphy in order to obtain precise data regarding remnant liver function before hepatectomy. We investigated 20 patients undergoing hepatectomy using the clearance rate of indocyanine green (KICG) as a parameter, and compared the predicted postoperative KICG obtained by CT and by transaxial single-photon emission tomographic (SPET) images acquired by 99mTc GSA liver scintigraphy before hepatectomy. In GSA studies, based on time-activity curves for the heart and liver, we compared HH15 (heart activity at 15 min divided by heart activity at 3 min), LHL15 (liver activity at 15 min divided by heart plus liver activity at 15 min) and KL (obtained from the time-activity curve for the liver) in 103 patients. In 58 patients without increased serum bilirubin, KL was compared with KICG. In four patients, occlusion of the right portal vein was performed with the aim of carrying out secondary hepatectomy, and changes in liver volume were compared between CT and 99mTc GSA liver scintigraphy. The correlation coefficient between the postoperative KICG predicted by CT and the actual postoperative KICG was rather poor, at r = 0.569 (P < 0.05); that between the postoperative KICG predicted by 99mTc GSA liver scintigraphy and the actual postoperative KICG was good, at r = 0.788 (P < 0.01); correlations between KL and HH15 and between KL and LHL15 in 103 patients were very good or good, at r = 0.906 (P < 0.001) and r = 0.807 (P < 0.001), respectively, and that between KL and KICG in 58 patients was very good, at r = 0.916 (P < 0.001). In all four cases of right portal vein occlusion, the remnant liver volume ratio was markedly increased after occlusion in GSA compared with CT, and the postoperative KICG predicted by GSA after occlusion was closer to the actual postoperative KICG than that predicted by CT. It is concluded that 99mTc GSA liver scintigraphy is useful for predicting remnant liver function before hepatectomy and for evaluating changes in regional liver function after occlusion of the portal vein unilaterally.     

1.6 Gbit/s optical receiver at 1.3 ?m with SAW timing retrieval circuit

The performance of a 1.6 Gbit/s optical receiver employing a s.a.w. filter as a timing tank is reported. The error-rate characteristics in a p.c.m. transmission system using a 1.3 ?m In-GaAsP laser and single-mode fibres were studied. The average received optical power at a 10?9 error rate was ?28 dBm. In a 15 km transmission experiment, the receiving level was degraded by 2 dB owing to fibre dispersion. Timing phase margin of 75 degrees after 12 km transmission was confined with the self-timed receiver.     

Magnetic properties of CeC2 and its solid solutions,CeXDy1−XC2

Magnetic properties of CeC₂ and its solid solutions, Ce_XDy_1?XC₂, were investigated. Cerium dicarbide has the highest Neel temperature, 30 K, of the cerium compounds with non-magnetic elements and a positive paramagnetic Curie temperature, +12 K. This Nèel temperature is greatly higher than that expected on the basis of the de Gennes factor. In order to explain this high Nèel temperature we propose an idea that a super exchange interaction via acetylide ion, C₂^2?, contributes much to the total magnetic exchange for CeC₂. The positive paramagnetic Curie temperature observed for CeC₂ are also discussed in terms of the crystal field effects. The Nèel temperature (T_N) for Ce_XDy_1?XC₂ has a minimum on the T_N vs. the de Gennes factor curve, while the paramagnetic Curie temperature (θ_p) varies almost linearly with the de Gennes factor. These behaviors of T_N and θ_p are understood based on a difference in the magnetic exchange between CeC₂ and DyC₂.