Parallel Post‐Polyketide Synthase Modification Mechanism Involved in FD‐891 Biosynthesis in Streptomyces graminofaciens A‐8890

To isolate a key polyketide biosynthetic intermediate for the 16‐membered macrolide FD‐891 ( 1 ), we inactivated two biosynthetic genes coding for post‐polyketide synthase (PKS) modification enzymes: a methyltransferase (GfsG) and a cytochrome P450 (GfsF). Consequently, FD‐892 ( 2 ), which lacks the epoxide moiety at C8–C9, the hydroxy group at C10, and the O‐methyl group at O‐25 of FD‐891, was isolated from the gfsF/gfsG double‐knockout mutant. In addition, 25‐O‐methyl‐FD‐892 ( 3 ) and 25‐O‐demethyl‐FD‐891 ( 4 ) were isolated from the gfsF and gfsG mutants, respectively. We also confirmed that GfsG efficiently catalyzes the methylation of 2 and 4 in vitro. Further, GfsF catalyzed the epoxidation of the double bond at C8‐C9 of 2 and 3 and subsequent hydroxylation at C10, to afford 4 and 1 , respectively. These results suggest that a parallel post‐PKS modification mechanism is involved in FD‐891 biosynthesis.     

Control of amylase and protease activities in a phytase preparation by ampholyte-free preparative isoelectric focusing for unrefined cereal-containing bread

Direct addition of a food additive-grade Aspergillus niger phytase preparation to 30% brown rice flour-added bread ingredients reduced the bread myo-inositol hexaphosphate (IP₆) content. The phytase preparation had protease and amylase activities. Addition of the crude phytase preparation induced bread crust collapse. Protease-free high- and low-amylase phytase fractions were prepared using preparative ampholyte-free isoelectric focusing (autofocusing). Addition of the protease-free low-amylase phytase fraction did not significantly affect loaf volume and did not collapse the crust. Addition of the protease-free high-amylase phytase fraction significantly increased loaf volume approximately 1.5× in the presence of amylase at 193–1029 U. However, addition of 1029 and 2058 U of amylase induced partial and whole bread crust collapse, respectively. Therefore, removal of protease and control of amylase activities in the phytase preparation are crucial in the preparation of brown rice flour-added bread with a low myo-inositol phosphate (IP₆) and good swelling property.     

Three‐Dimensional Simulation of Pressure Fluctuation in a Granular Solid Propellant Chamber within an Ignition Stage

The effects of the conditions of the ignition system in the propellant chamber of a gun system using a granular solid propellant are numerically investigated with respect to ignition performance criteria such as the differential pressure generation between the breech and the projectile base. Simulations, in which the length of the primer and the igniter mass are varied, are performed using a solid/gas two‐phase fluid dynamics code for three‐dimensional calculation of gas flow and discrete solid propellant particles. This code simulates the igniter combustion in the primer, the movement of burning solid propellant grains, and the formation of pressure gradients inside the chamber in the ignition process. The differential pressures between the breech and the projectile base measured in experiments are well predicted by the simulations for various igniter conditions. In the process of igniting the solid propellant, the propellant grains are accelerated toward the projectile base by the igniter gas flows from the primer vents. Fixed‐particle simulation is also carried out in order to examine the effects of the movement of the solid propellant grains on the chamber pressure profile. The simulated results reveal that the movement of solid propellant grains causes differential pressure fluctuations, which depend on the discharge from the primer vents and the locations of these vents.     

Numerical Prediction of Interior Ballistics Performance of Projectile Accelerator Using Granular or Tubular Solid Propellant

Two‐dimensional axisymmetric interior ballistics simulations in projectile acceleration systems that use granular or long slotted tubular solid propellants are performed using the solid/gas two‐phase fluid dynamics code of the Euler‐Lagrange approach. For validation, the simulation results are compared with experimental data for tubular solid propellants. In the series of the interior ballistics simulations, the propellant grain size and shape effects on the firing performance of 50 mm gun are numerically investigated. The propellant grain size and shape affect the energy release rate of the solid propellant charged in the chamber, the projectile kinetic energy at the muzzle, and even the fluctuations of the chamber pressure history. An appropriate burning surface area of the propellant grain exists, so that the projectile can achieve the maximum kinetic energy from the released energy of the solid propellant. Based on the simulation results, guidelines are proposed for the grain size design that enables the propellant energy to be used efficiently.     

High-resolution inventory of Japanese anthropogenic mercury emissions

Heavy metals like mercury that are emitted into the environment remain there indefinitely, posing a long-term threat to both the environment and human health. Elemental mercury is volatile and is in gaseous form, and because of the long residence time, transported over long distances. Comprehensive control of mercury emissions therefore remains an important international issue. The crucial steps for designing effective approaches for such control include the quantification of mercury emissions by sources and the identification of geographical characteristics of the emissions. In this study a detailed, high-resolution inventory of Japanese mercury emissions in 2005 was developed to improve understanding of their geographical distribution. Proceeding from a national emissions inventory per source category, emissions were spatially allocated with increasing geographical resolution in a stepwise procedure using statistics from geographic information resources, yielding mercury emissions per prefecture, per municipality and per grid cell of approximately 1 × 1 km. The five prefectures with the highest emissions were Fukuoka, Yamaguchi, Hyogo, Oita, and Hokkaido, accounting for 35.2% of all emissions. In each prefecture a small number of municipalities account for a major share of emissions. Distribution by grid cell is characterized by a concentration of 50% of all emissions in a mere 32 of the 255?954 grid cells over which emissions are distributed in this study. It was also quantitatively confirmed that use of larger grid cells leads to greater uncertainty in emissions distribution. Problems with data collection are clarified and measures to improve the accuracy of future estimation are proposed.     

冲击电压下残余电荷对沿面放电发展的影响

固体绝缘的表面是高压电力设备绝缘的最薄弱环节,很多绝缘事故都是由沿面放电造成的。发生放电后,电荷会在绝缘表面积聚,会很大程度上影响下一次放电的产生与发展。为此,通过观测在极性交替变化的冲击电压作用下沿同轴圆柱形聚对苯二甲酸乙二醇酯(PET)绝缘表面放电的发展以及测量放电后表面残余电荷电位的分布,来研究残余电荷对沿面放电的影响。研究表明,在改变冲击电压的极性后,由于反极性残余电荷的影响,放电会被促进,放电通道会沿着前一次放电的通道向前发展,并且会比前一次放电距离略长,放电的强度会增强,放电的发展速度也会加快。在沿着放电通道方向,表面电荷电位梯度可以明显分为两部分:在放电头部的20mm区域,电位梯度较大,为流注放电;而在后面的主干部,电位梯度平缓,为先导放电。     

Study on the retention behavior of hydrogen isotopes and the change of chemical states of boron film exposed to hydrogen plasma in LHD

The behavior of hydrogen retention and the change of chemical states of boron film exposed to hydrogen plasma in LHD were investigated. The sample was prepared in LHD, and atomic concentrations for the boron film after hydrogen plasma exposure were changed from 75% for boron, 15% for carbon and 8% for oxygen to 53%, 18% and 22%, respectively. BC bond was a major chemical state of the boron film after hydrogen plasma exposure, although abundance of BB bond was the highest before the plasma exposure. Total hydrogen retention measured by TDS was evaluated to be 1.7 × 10²⁰ H m^?2, and the retentions of hydrogen as BHB, BH and BCH bonds were, respectively, 4.8 × 10¹⁹, 7.2 × 10¹⁹ and 5.2 × 10¹⁹ H m^?2. It was concluded that the hydrogen retention could be estimated by taking account not only of chemical states of impurities, but also of hydrogen depth profile.     

Statistical estimate of mercury removal efficiencies for air pollution control devices of municipal solid waste incinerators

Although representative removal efficiencies of gaseous mercury for air pollution control devices (APCDs) are important to prepare more reliable atmospheric emission inventories of mercury, they have been still uncertain because they depend sensitively on many factors like the type of APCDs, gas temperature, and mercury speciation. In this study, representative removal efficiencies of gaseous mercury for several types of APCDs of municipal solid waste incineration (MSWI) were offered using a statistical method. 534 data of mercury removal efficiencies for APCDs used in MSWI were collected. APCDs were categorized as fixed-bed absorber (FA), wet scrubber (WS), electrostatic precipitator (ESP), and fabric filter (FF), and their hybrid systems. Data series of all APCD types had Gaussian log-normality. The average removal efficiency with a 95% confidence interval for each APCD was estimated. The FA, WS, and FF with carbon and/or dry sorbent injection systems had 75% to 82% average removal efficiencies. On the other hand, the ESP with/without dry sorbent injection had lower removal efficiencies of up to 22%. The type of dry sorbent injection in the FF system, dry or semi-dry, did not make more than 1% difference to the removal efficiency. The injection of activated carbon and carbon-containing fly ash in the FF system made less than 3% difference. Estimation errors of removal efficiency were especially high for the ESP. The national average of removal efficiency of APCDs in Japanese MSWI plants was estimated on the basis of incineration capacity. Owing to the replacement of old APCDs for dioxin control, the national average removal efficiency increased from 34.5% in 1991 to 92.5% in 2003. This resulted in an additional reduction of about 0.86 Mg emission in 2003. Further study using the methodology in this study to other important emission sources like coal-fired power plants will contribute to better emission inventories.     

PER1, GUP1 and CWH43 of methylotrophic yeast Ogataea minuta are involved in cell wall integrity

In eukaryotes, the glycosylphosphatidylinositol (GPI) modification of many glycoproteins on the cell surface is highly conserved. The lipid moieties of GPI‐anchored proteins undergo remodelling processes during their maturation. To date, the products of the PER1, GUP1 and CWH43 genes of the yeast Saccharomyces cerevisiae have been shown to be involved in the lipid remodelling. Here, we focus on the putative GPI remodelling pathway in the methylotrophic yeast Ogataea minuta. We found that the O. minuta homologues of PER1, GUP1 and CWH43 are functionally compatible with those of S. cerevisiae. Disruption of GUP1 or CWH43 in O. minuta caused a growth defect under non‐permissive conditions. The O. minuta per1Δ mutant exhibited a more fragile phenotype than the gup1Δ or cwh43Δ mutants. To address the role of GPI modification in O. minuta, we assessed the effect of these mutations on the processing and localization of the O. minuta homologues of the Gas1 protein; in S. cerevisiae, Gas1p is an abundant and well‐characterized GPI‐anchored protein. We found that O. minuta possesses two copies of the GAS1 gene, which we designate GAS1A and GAS1B. Microscopy and western blotting analysis showed mislocalization and/or lower retention of Gas1Ap and Gas1Bp within the membrane fraction in per1Δ or gup1Δ mutant cells, suggesting the significance of lipid remodelling for GPI‐anchored proteins in O. minuta. Localization behaviour of Gas1Bp differed from that of Gas1Ap. Our data reveals, for the first time (to our knowledge), the existence of genes related to GPI anchor remodelling in O. minuta cells.