Efficient cleavage of RNA at high temperatures by a thermostable DNA-linked ribonuclease H

To construct a DNA-linked RNase H, which cleaves RNA site-specificallyat high temperatures, the 15-mer DNA, which is complementaryto the polypurine-tract sequence of human immunodeficiency virus-1RNA (PPT-RNA), was cross-linked to the unique thiol group ofCys135 in the Thermus thermophilus RNase HI variant. The resultantDNA-linked enzyme (d15-C135/TRNH), as well as the d15-C135/ERNH,in which the RNase H portion of the d15-C135/TRNH is replacedby the Escherichia coli RNase HI variant, cleaved the 15-merPPT-RNA site-specifically. The mixture of the unmodified enzymeand the unlinked 15-mer DNA also cleaved the PPT-RNA but ina less strict manner. In addition, this mixture cleaved thePPT-RNA much less effectively than the DNA-linked enzyme. Theseresults indicate that the cross-linking limits but acceleratesthe interaction between the enzyme and the DNA/RNA substrate.The d15-C135/TRNH cleaved the PPT-RNA more effectively thanthe d15-C135/ERNH at temperatures higher than 50°C. Thed15-C135/TRNH showed the highest activity at 65°C, at whichthe d15-C135/ERNH showed little activity. Such a thermostableDNA-linked RNase H may be useful to cleave RNA molecules withhighly ordered structures in a sequence-specific manner.     

Single-pass desalination of high salinity sea water with reverse osmosis

Two types of new “HOLLOSEP” have been developed for single-pass desalination of high salinity seawater. One is a high pressure and high temperature module, type “HPT”. The performance of this new type HOLLOSEP is analyzed in the case of desalination of high salinity seawater under a high pressure Of 75Kg/cm² G at high temperature of 40°C. It has been found that the operation costs can be reduced by this high pressure and high temperature operation system.The other is a large size module containing five elements of 12 inches diameter, type “JM-12”. This module has been developed to reduce the water cost by enlarging the diameter and the length of a vessel coupled with the improvement in water flux rate of the hollow fiber membranes. The fresh water productivity of this module is 150m³/day under the conditions of 3.5% NaCl feed water, 30% product water recovery at 55kg/cm²G.     

Micropore size estimation on gas separation membranes: A study in experimental and molecular dynamics

The effect of the gas molecular size and its affinity to the pore surface on gas permeation properties through the ceramic membranes was studied by both the gas permeation experiments and gas permeation simulations using a nonequilibrium molecular dynamics (MD) technique. A modified gas permeation model equation based on the gas translation (GT) mechanism was presented. MD simulation revealed that the effective diffusion length in a micropore depended on the gas molecular size, and the pre‐exponential coefficient of a modified GT model equation showed good correlation with the kinetic diameter of the gas molecules. Also presented is a simple method to estimate the mean pore size of microporous membranes. The estimated pore sizes were consistent with observed kinetic diameter dependencies of gas permeance for real silica membranes. The pore size of a Deca‐Dodecasil 3R (DDR) zeolite membrane was also reasonably estimated at ～0.4 nm from the reported gas permeation data. © 2012 American Institute of Chemical Engineers AIChE J, 59: 2179–2194, 2013     

Identification and Characterization of the Streptazone E Biosynthetic Gene Cluster in Streptomyces sp. MSC090213JE08

Streptazone derivatives isolated from Streptomyces species are piperidine alkaloids with a cyclopenta[b]pyridine scaffold. Previous studies indicated that these compounds are polyketides, but the biosynthetic enzymes responsible for their synthesis are unknown. Here, we have identified the streptazone E biosynthetic gene cluster in Streptomyces sp. MSC090213JE08, which encodes a modular type I PKS and tailoring enzymes that include an aminotransferase, three oxidoreductases, and two putative cyclases. The functions of the six tailoring enzymes were analyzed by gene disruption, and two putative biosynthetic intermediates that accumulated in particular mutants were structurally elucidated. On the basis of these results, we propose a pathway for the biosynthesis of streptazone E in which the two putative cyclases of the nuclear transport factor 2–like superfamily are responsible for C?C bond formation coupled with epoxide ring opening to give the five‐membered ring of streptazone E.     

Research on laser-arc hybrid welding of lap fillet joints of thin sheet

ABSTRACT

Laser welding is capable of welding at high speeds by high-density energy, while arc welding is an effective construction method from the viewpoint of tolerance of the gap and welding position. Laser-arc hybrid welding has both these features. The authors have researched suitable welding parameters and consumables for this hybrid welding process that couples laser beam with MAG arc for lap fillet weld joining of thin steel sheets. As a result, the following welding parameters have been proven to be the most appropriate for better bead shapes and root-gap tolerance, i.e. laser leading (kept at a right angle) and MAG trailing (kept at a push angle); the laser-arc distance was 3 mm and the laser beam focus size was 2 mm. In addition, it was proven that HT490-class welding wire of Si-Mn-Ti type (JIS YGW11) was the most appropriate for better bead shapes and root-gap tolerance. The bead shape was apt to be better in cases of higher surface tension of welding wire. The result of the tensile shear test of the joint by welding with HT490-class welding wire of Si-Mn-Ti type (JIS YGW11) under selected welding condition demonstrated that the value of the tensile strength of parent material was equal to that of lab fillet joints.     

Improving the Palatability of Salt-Reduced Food Using Dried Bonito Stock

ABSTRACT:  The characteristic flavors, with the exception of umami, of dried bonito stock not only enhanced saltiness but also improved palatability, namely the acceptability, of salt-reduced foods. However, the respective effects of odorants and tastants of dried bonito stock on palatability have yet to be fully explained. Thus, the effect of dried bonito stock aroma on saltiness enhancement and palatability improvement in salt-reduced food was evaluated by sensory assessment. Probit analysis indicated that aromas of the stocks,  arabushi  and  karebushi , did not affect the intensity of saltiness. However, the test sample with aromas of dried bonito stocks was significantly more palatable than the reference sample. The effects of the taste of dried bonito stock were also evaluated. Probit analysis indicated that enhanced saltiness was not observed in the MSG solution but was observed with the dried bonito stocks, when controlled for aroma. These results suggest that saltiness enhancement by dried bonito stock was caused by the characteristic taste (excluding umami) of dried bonito stock, while its characteristic aroma and umami were involved in preventing the loss of palatability of a low-salt diet. Moreover, it was found that using a combination of  karebushi  and dried kelp, as material for making stock, could contribute effectively to the preparation of palatable salt-reduced foods in Japan. Invention of new seasonings for improving the palatability of salt-reduced foods could exploit these findings.     

Current status of Japanese thermal power plants and life assessments of high temperature steam and gas turbine components

More than 80% of prime energy is now supplied by thermal power plants in Japan since the Great East Earthquake of 2011 and more than two thirds of them were operated for over 30 years. Evaluation of the residual life of those aged plants are, therefore, required to maintain reliability and also to avoid premature retirement. Several kinds of life assessment technologies for the high temperature components of aged steam and gas turbines have already been developed and applied to actual components. Further developments for the advanced ones are now still being conducted. The current status of Japanese thermal power plants is briefly overviewed and the life assessment technologies developed for evaluating the material degradation and component damage conditions and life extension capabilities of steam and gas turbines are explained with some examples of the applications. The differences between the development concepts and the methods developed for both turbines are also explained along with those of the design specifications.     

Direct‐contact heat exchange between fluidizing particles and a heat transfer surface in a fluidized bed: Temperature visualization of fluidizing particles

Heat conduction during contact between a heat transfer surface and fluidizing particles, a phenomenon which is one of the effective heat transfer mechanisms in a gas–solid fluidized bed, has been empirically investigated. The temperature profile of the fluidizing particles during the contact period is visualized with the aid of an infrared imager. The visualization reveals that the particles have been considerably heated in the thermal boundary layer on the heat transfer surface before contact. Based on the visualized temperature profile of the particles, the contact conductance between a fluidizing particle and the heat transfer surface is estimated by an in inverse analysis. Using the evaluated contact conductance, the contributions of the conductive heat transfer to the total heat transfer are also evaluated. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(3): 165–181, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10027     

Fluctuation analysis of partial discharge pulse occurrence with an integral equation

This paper proposes an integral equation to describe the stochastic fluctuation of partial discharge (PD) occurrence under sinusoidal voltage stress based on a simple PD model. In the model, the stochastic behavior of PD fluctuation is assumed to arise from the fluctuation of the PD delay time after the inception voltage is built up across a discharge gap. For simplicity of calculation, the delay time is assumed to have an exponential distribution. Based on these assumptions, it is found that the proposed integral equation provides the basic characteristics such as the PD pulse distribution in the applied voltage phase angle domain. The authors have solved the equation numerically and demonstrate several ?–n distribution patterns with average delay times of 0.05 to 5 ms at low applied voltage. The solution is compared with PD characteristics obtained by Monte Carlo simulation based on the same PD model, and good agreement is found. © 2001 Scripta Technica, Electr Eng Jpn, 136(1): 16–28, 2001