In this study, a facultative bacterium that converts fumarate to succinate at a high yield was isolated. The yield of biocon
version was enhanced about 1.2 times by addition of glucose into culture medium at an initial concentration of 6 g/L. When
the initial cell density was high (2 g/L), the succinate produced at pH 7.0 for initial fumarate concentrations of 30, 50,
80, and 100 g/L were 29.3, 40.9, 63.6, and 82.5 g/L, respectively, showing an increase with the initial fumarate concentration.
The high yield of 96.8%/mole of fumarate in just 4 h was obtained at the initial fumarate concentration of 30 g/L. Comparing
these values to those obtained with low cell culture (0.2 g/L), we found that the amount of succinate produced was similar,
but the production rate in the high cell culture was about three times higher than was the case in the low cell culture. This
strain converted fumarate to succinate at a rate of 3.5 g/L·h under the sparge of CO2. 相似文献
The nonenzymatic hydrolysis of RNA by polyvinylpyrrolidone (PVP) has been investigated. A bell-shaped kinetics was observed
when the first order rate constant of the reaction was ploted as a function of PVP concentration, which means the kinetic
feature of PVP as a degradative receptor distinct from those of degradative enzymes (e.g., ribonuclease). 相似文献
Four different Ni/YSZ cermets were prepared by combining two sets of NiO and YSZ powders of different size. The microstructural
change evolved during the course of electrode adhesion and cell operation was monitored using scanning electron microscopy
(SEM) and energy dispersive spectroscopy (EDS). The anodic activity was compared by analyzing the ∝ impedance spectra of four
Ni/YSZ cermet (H2) / YSZ half cells at 1000 °C. Among the cermets, the one that prepared from the smaller NiO and larger YSZ powder showed
the best anodic performances on aspects of the initial activity and long-term stability. This favorable performance is partly
responsible to the presence of larger YSZ particles which provide a supporting matrix to suppress the microstructural change
against Ni sintering and concomitant volume shrinkage, and partly to an easy formation of Ni channel for electronic conduction.
Anodic performances of the other cermets were also discussed based on their microstructure. 相似文献
Molecular weight averages have long been used as a measure of polymer molecular weight properties in industrial polymer manufacturing processes. With a kinetic model, it is possible to directly calculate the polymer chain length distribution by integrating an infinite number of the polymer population balance equations. However, when the polymer chain length is very large, such a direct integration of polymer population balance equations can be computationally demanding. In this paper, the method of finite molecular weight moments is applied to the calculation of polymer chain length distribution in a batch free radical thermal polymerization of styrene. The weight fraction of a finite chain length interval is directly calculated in conjunction with a kinetic model. The method of calculation is illustrated through model simulations. 相似文献
The addition of pyridine N -oxide is necessary to obtain high enantioselectivities in the asymmetric aziridination of styrene derivatives through transfer of a nitrogen atom from chiral, toluenesulfonic anhydride activated nitridomanganese complex 1 [Eq. (a)]. Remarkably, high stereospecificity was observed in all the aziridinations of trans- and cis-1,2-disubstituted alkenes. R1=H, Me, nPr, iPr; R2=H, Me; Ts=p-toluenesulfonyl. 相似文献
A radical chain addition of allyl bromides 2 to alkenylcyclopropanes 1 resulted in [3+2] annulation to give 2-bromomethylalkenylcyclopentanes 3 in good yields(16 examples). In this reaction, two kinetically fast radical reactions, cyclopropylcarbinyl radical-ring-opening and 5-exo-radical cyclization, preceded the β-fragmentation of a bromine radical to make the formal cycloaddition possible. 相似文献
Interaction chromatography has been employed to validate that adsorption of poly[styrene‐co‐(4‐bromostyrene)] (PBrxS) random copolymers, where x denotes the mole fraction of 4‐bromostyrene (4–BrS) in PBrxS in solution depends on the average number of adsorptive segments, the type of adsorbing substrate, and on the co‐monomer sequence distribution in PBrxS.
Rare-earth-doped oxynitride or nitride compounds have been reported to be photoluminescent and may then serve as new phosphors
because of their good thermal and chemical stabilities. In this work, Eu2+-doped β-SiAlON phosphor with a composition of EuxSi6−zAlzOzN8−z (x=0.018, z=0.23) was prepared by gas-pressured solid state reaction. The crystallinity and particle morphology of the prepared phosphor
were characterized. The Stokes shift and zero-phonon line were calculated mathematically and estimated from the spectral data.
The temperature dependence of photoluminescence was measured from 25 to 250°C. The prepared Eu2+-doped β-SiAlON green phosphor showed superior thermal quenching property compared to silicate (SrBaSiO4:Eu2+) green phosphor. The white light-emitting diode (LED) back-lighting unit (BLU) using the prepared β-SiAlON:Eu2+ green phosphor exhibited higher color gamut than a commercial silicate phosphor. 相似文献
The article summarizes research activities of the Laser Thermal Laboratory on pulsed nanosecond and femtosecond laser-based
processing of materials and diagnostics at the nanoscale using optical-near-field processing. Both apertureless and apertured
near-field probes can deliver highly confined irradiation at sufficiently high intensities to impart morphological and structural
changes in materials at the nanometric level. Processing examples include nanoscale selective subtractive (ablation), additive
(chemical vapor deposition), crystallization, and electric, magnetic activation. In the context of nanoscale diagnostics,
optical-near-field-ablation-induced plasma emission was utilized for chemical species analysis by laser-induced breakdown
spectroscopy. Furthermore, optical-near-field irradiation greatly improved sensitivity and reliability of electrical conductance
atomic force microscopy enabling characterization of electron tunneling through the oxide shell on silicon nanowires. Efficient
in-situ monitoring greatly benefits optical-near-field processing. Due to close proximity of the probe tip with respect to
the sample under processing, frequent degradation of the probe end occurs leading to unstable processing conditions. Optical-fiber-based
probes have been coupled to a dual-beam (scanning electron microscopy and focused ion beam) system in order to achieve in-situ
monitoring and probe repair. 相似文献
Inorganic species formation in a discharged water generating (DWG) system consisting of a plane-to-plane electrode arrangement with a 20 kV, 20 mA and 1 kHz power source has been investigated. The DWG system is able to produce the various oxidants HNO2, HNO3 and O3, as well as OH radicals and many other unconfirmed radicals. These products can play an important role in the advanced oxidation of organic compounds and in rot protection. The pH of water discharged from the system for 20 min during inflow of natural air was about 3, nitrogen concentrations of nitrite and nitrate were 4.6 mg/L and 7.9 mg/L, respectively, residual dissolved ozone concentration was 0.7 mg/L and the oxidation power as measured by KI titration methods was approximately equivalent to 46 mg-O3/L. 相似文献