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851.
Itano Y Bandow H Takenaka N Saitoh Y Asayama A Fukuyama J 《The Science of the total environment》2007,379(1):46-55
We investigated the relationships between ambient O(3) concentrations and the concentrations of its precursors, NO(x) and NMHC, in Osaka, Japan. The levels of O(x)' (where [O(x)']=[O(3)]+[NO(2)]-0.1x[NO(x)] where the last term accounts for primary emissions of NO(2)) were uniform within the city even in the photochemically active season. We suggested that NO oxidation by peroxy radicals was a minor contributor, and that oxidation of locally emitted NO by background O(3) in the city was the primary control on NO(2) concentrations. Ozone concentrations increased linearly from 1985 to 2002 at a rate of 0.6 ppbv/yr, even though O(x)' concentrations remained constant after the mid 1990s. The trend for O(x)' concentrations could not be explained in terms of an increase in local O(3) production, and the trend was found to reflect background O(3) concentrations in Japan. There was a clear relationship between the NO(2)/O(x)' ratio and NO(x) concentration: the ratio decreased with decreasing NO(x) concentration. As a consequence, O(3) increased with decreasing NO(x) concentration. The reduction of NO(x) emissions was deemed to be an important factor for the recent trend of increasing O(3) concentrations in Osaka City. 相似文献
852.
The community structure, spatial distributions, and in situ activity of ammonia-oxidizing bacteria (AOB) representing the Betaproteobacteria and nitrite-oxidizing bacteria (NOB) representing the genus Nitrospira in three different river sediments with different pollution sources and levels along the Niida River, Hachinohe, Japan, were investigated by the combined use of 16S rRNA gene-cloning analysis, real-time quantitative polymerase chain reaction (RTQ-PCR) assays, and microelectrodes. The goal of this research was to evaluate the contribution of nitrifying activity in the sediment to the overall nitrogen elimination rate in this river. The 16S rRNA gene-cloning analysis revealed that the community structures of AOB and Nitrospira-like NOB are present in three sediments. On the basis of the results of 16S rRNA gene-cloning analysis, the RTQ-PCR assay using a TaqMan probe was developed and optimized for the quantification of the Nitrospira-like NOB. In the sediments, AOB specific 16S rRNA genes were detected in the range of 10(6) to 10(7) copies/cm3 and evenly distributed over the sampled sediment depth (0-5 mm), whereas the Nitrospira-like NOB 16S rRNA gene copy numbers per cm3 were 1-2 orders of magnitude higher than the AOB copy numbers. Under light conditions, intensive oxygenic photosynthesis occurred in the surface and increased the maximal O2 concentration and O2 penetration depth in all sediments. This concomitantly stimulated nitrifying bacteria present in diurnally anoxic deeper zones and expanded nitrification zones, which consequently increased the total NH4+ consumption rate in the sediment (i.e., total NH4+ flux into the sediment). The results suggested that the in situ nitrifying activity was restricted mainly to the surface 2 mm of the sediment and linked with photosynthetic activity, which obviously plays an important role in nitrogen elimination in this river. 相似文献
853.
Yuanxia Sun Shigeru Hayakawa Masahiro Ogawa Supaporn Naknukool Yupin Guan Yoshiyuki Matsumoto 《Food science and biotechnology》2011,20(2):303-310
Solid wastes of freshwater clam in food processing, including mainly mantle, were used as a raw material for the recovery
of bioactive peptides related to angiotensin I-converting enzyme (ACE) inhibitor. Among the primary hydrolysates of dried
mantle (DM), the peptides corresponding to hydrolysates using 2 crude peptidases exhibited a strong ACE inhibitory activity
(IC50, 0.23 mg/mL), and recovery efficiency of soluble materials and their protein content were considerably large with 42.65%
and 468.6 mg/g, respectively. The ACE inhibitory activity of all secondary hydrolysates digested by pepsin and trypsin was
significantly increased as compared to primary hydrolysates. Furthermore, the peptic secondary hydrolysates were fractionated
by gel filtration and reverse phase-HPLC (RP-HPLC) and characterized by matrix-assisted laser desorption-ionization time of
flight/mass spectrometry (MALDI-TOF/MS). These peptides with molecular weight of less than 1 kDa possessed the stronger ACE
inhibitory effect, and their inhibitory pattern was found to be competitive. The results showed that the DM hydoplysates might
be utilized as a rich source of bioactive peptide. 相似文献
854.
An analytical method of stochastic seismic response and reliability analysis of hysteretic structures based on the theory of Markov vector process is presented, especially from the methodological aspect. To formulate the above analysis in the form of stochastic differential equations, the differential formulations of general constitutive laws for a class of hysteretic characteristics are derived. The differential forms of the seismic safety measures such as the maximum ductility ratio, cumulative plastic deformation, low-cycle fatigue damage are also derived. The state equation governing the whole nonlinear dynamical system which is composed of the shaping filter generating seismic excitations, hysteretic structural system and safety measures is determined as the Itô stochastic differential equations. By introducing an appropriate non-Gaussian joint probability density function, the statistics and joint probability density function of the state variables can be evaluated numerically under nonstationary state. The merit of the proposed method is in systematically unifying the conventional response and reliability analyses into an analysis which requires knowledge of only first order (single-time) statistics or probability distributions. 相似文献
855.
Ryotaro Shimada Tsutomu Kono Koji Masuda Yoshiyuki Komoda 《Advanced Powder Technology》2019,30(4):774-785
Aimed at optimizing the resin-molding process, a method for numerically analyzing aggregation and dispersion behavior of the filler in resin composite was proposed. The flow of a resin composite during molding was calculated by using computational fluid dynamics (CFD), and particle-size distribution (PSD) of the cluster in each computational domain of the CFD model was estimated by solving the population balance equation (PBE). The proposed numerical-analysis method is based on the thixotropy model of Usui et al. In the thixotropy model, PSD is calculated by taking into account the aggregation and dispersion rate of the cluster by Brownian coagulation, shear coagulation, and shear breakage. Shear-breakage rate of the cluster is evaluated by solving the energy balance of bonding energy of the primary particles cut at the breakage and the drag applied to the cluster by the flow of the fluid. The composite viscosity was calculated using Krieger and Dougherty’s model based on apparent-solid-volume fraction estimated from the calculated PSD. To solve the PBE at low calculation cost, it was discretized using the fixed-pivot technique of Kumar and Ramkrishna. The proposed method was incorporated into the general-purpose CFD software FLOW-3D®, and its accuracy was proved. 相似文献
856.
Raw sago starch digesting amylase was obtained from Penicillium brunneum No. 24. with strong ability to digest sago starch granules. The crude enzyme from this strain contains CMC-ase and avicelase. The specific activity of the enzyme did not increase proportionally with purification. We tried combination of our purified enzyme with other hydrolytic enzymes as a means of improving the hydrolysis of sago starch granules. Addition of cellulase at the initial stage of the hydrolyzation process resulted in an increase in the ability of raw starch digesting amylase to digest sago starch granules. Adding 10 unit/g starch of cellulase. followed of our purified raw starch digesting amylase in small portion at various time intervals was found effective in the hydrolysis of untreated sago starch granules. The treatment resulted in a convertion rate of untreated sago starch granules to glucose near to complete after 120h enzymes reaction, and was also effective in reducing the reaction time of hydrolysis of treated sago starch granules. This process showed that mainly glucose was produced. 相似文献
857.
Polymer-derived ceramics (PDCs) are being actively explored in various fields today because of their unique physiochemical properties. Very recent advances in the use of PDCs in energy storage technologies (e.g., batteries, supercapacitors) have motivated researchers to explore the possibilities of PDCs as electrocatalysts for use in energy conversion reactions. Impressively, the tunable functional properties, especially the electrical properties, of PDCs have helped to break through this “bottleneck” and enabled them to become promising materials for use in electrocatalytic conversion. This review presents an in-time summary of the progress in the development of PDCs for electrochemical energy conversion. First, a general introduction to the preparation of PDCs is provided. Later, the factors (e.g., chemical stability, electron conductivity) most closely related to electrocatalytic performance are discussed. Specifically, the parameters that affect the electron conductivity of PDCs are enumerated to delve into advanced strategies for achieving effective electrocatalysts. The relevant electrocatalytic conversion reactions (e.g., hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction) and utilization of PDCs in these reactions are also comprehensively introduced. Finally, the current challenges and future opportunities for PDC materials in the field of electrochemical energy conversion are summarized. 相似文献