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91.
Hajime Masukawa Hidehiro Sakurai Robert P. Hausinger Kazuhito Inoue 《International Journal of Hydrogen Energy》2014
Heterocyst-forming cells of the cyanobacterium Anabaena sp. strain PCC 7120 ΔHup, lacking an uptake hydrogenase, photobiologically produce H2 by nitrogenase. Under N2-rich atmosphere, the nitrogenase activity declines in a rather short time due to the sufficiency of combined nitrogen. From the parental ΔHup strain, site-directed double-crossover variants, dc-Q193S and dc-R284H, were created with amino acid substitutions presumed to be located in the vicinity of the FeMo-cofactor of nitrogenase. Unlike the case for the ΔHup strain, H2 production activities of the variants were not decreased by the presence of high concentrations of N2 and they continuously produced H2 over 21 days with occasional headspace gas replacement. This property of N2 insensitivity is a potentially useful strategy for reducing the cost of the culture gas in future practical applications of sustainable biofuel production. This Anabaena strain has only the Mo-containing nitrogenase which reduces acetylene to ethylene, but the dc-Q193S variant also produced ethane at low but measurable rates along with greater rates of ethylene production. 相似文献
92.
Feasible external control of material properties is a crucial issue in condensed matter physics. A new approach to achieving this aim, named adiabatic photo-steering, is reviewed. The core principle of this scheme is that several material constants are effectively turned into externally tunable variables by irradiation of monochromatic laser light. Two-dimensional topological insulators are selected as the optimal systems that exhibit a prominent change in their properties following the application of this method. Two specific examples of photo-steered quantum phenomena, which reflect topological aspects of the electronic systems at hand, are presented. One is the integer quantum Hall effect described by the Haldane model, and the other is the quantum spin Hall effect described by the Kane–Mele model. The topological quantities associated with these phenomena are the conventional Chern number and spin Chern number, respectively. A recent interesting idea, time-reversal symmetry breaking via a temporary periodic external stimulation, is also discussed. 相似文献
93.
94.
95.
Koshi Takenaka Masayoshi Ichigo Taisuke Hamada Atsushi Ozawa Takashi Shibayama Tetsuya Inagaki 《Science and Technology of Advanced Materials》2014,15(1)
Magnetostructural correlations in antiperovskite manganese nitrides were investigated systematically for stoichiometric and solid solution Mn3Cu1?xAxN (A = Co, Ni, Zn, Ga, Ge, Rh, Pd, Ag, In, Sn or Sb). This class of nitrides is attracting great attention because of their giant negative thermal expansion, which is achieved by doping Ge or Sn into the A site as a relaxant of the sharp volume contraction on heating (spontaneous volume magnetostriction ωs) because of the magnetovolume effects. The physical background of large ωs and mechanism of how the volume contraction becomes gradual with temperature are central concerns for the physics and applications of these nitrides. An entire dataset of thermal expansion, crystal structure and magnetization demonstrates that the cubic triangular antiferromagnetic state is crucial for large ωs. The intimate relationship between ωs and the magnetic structure is discussed in terms of geometrical frustration related to the Mn6N octahedron and magnetic stress concept. The results presented herein also show that ωs depends on the number of d electrons in the A atom, suggesting the important role of the d orbitals of the A atom. Not all the dopants in the A site, but the elements that disturb the cubic triangular antiferromagnetic state, are effective in broadening the volume change. This fact suggests that instability neighboring the phase boundary is related to the broadening. The relation between the gradual volume change and the local structure anomaly is suggested by recent microprobe studies. 相似文献
96.
Zhiling Li Yasushi Inoue Suyin Yang Naoko Yoshida Arata Katayama 《Journal of Bioscience and Bioengineering》2010,110(3):326-332
A mass balance and kinetic investigation of anaerobic dechlorination of pentachlorophenol (PCP) was undertaken using an enriched microbial consortium in a laboratory scale continuous flow column, as a model microbial permeable reactive barrier. The chlorine balance showed that 50 µM PCP was largely dechlorinated to phenol with the formation of a small quantity of 3-chlorophenol as an intermediate metabolite (hydraulic retention time 7.6 days), and the chlorine removal efficiency reached 36 µM d-1. When the initial PCP concentration was increased to 100 µM the chlorine removal efficiency increased 1.5 times. However, the dechlorination activity disappeared after 7.4 pore volumes (58 days), demonstrating the susceptibility of the dechlorination culture to high concentrations of PCP. Lactate released hydrogen as an electron donor during PCP dechlorination, with acetate, propionate, CO2 and CH4 as byproducts. The carbon balance showed that some of the organic carbon source (PCP, lactate) in the influent was converted to gas and utilized for biomass growth in addition to organic metabolites. The kinetic study was conducted in a batch culture and yielded 1.99 mg l-1 biomass growth per unit of chlorine consumption (µM). The Monod equation was well fitted to the specific growth rate of 1.38 d-1 and a half saturation constant of 0.29 µM. The organic chlorine removal rate in the batch culture was consistent with the results in the flow column, indicating the feasibility of and potential for in situ estimation and prediction through batch culture studies. 相似文献
97.
Soichi Hirota Shuhei Inoue Takahito Inoue Yoshifumi Kawai Yasutaka Wada Takashi Noguchi Yukihiko Matsumura 《Korean Journal of Chemical Engineering》2016,33(4):1261-1266
Supercritical water gasification (SCWG) has attracted attention as a technology for utilizing wet biomass. We used a fluidized bed of alumina particles to prevent blockage of a SCWG reactor. A glucose solution was heated in the reactor with and without fluidized alumina particles. In the absence of alumina particles, char particles formed homogeneously in the reactor, but the use of a fluidized bed resulted in accumulation of char particles at the reactor’s exit rather than inside the reactor. Therefore, the fluidized bed was effective at preventing blockage of the reactor. However, the alumina particles did not remove deposits from the reactor’s walls. Instead, the fluidized bed caused larger char particles to form, preventing their adhesion to the reactor’s wall. 相似文献
98.
Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) is an engineering plastic with high heat distortion temperature. Melt processing of neat PPE is usually accompanied with thermal degradation. The degradation problem is solved by blending with polystyrene to reduce the processing temperature. We propose an alternative using triallylisocyanurate (TAIC). TAIC is a low viscosity liquid that can be cured by peroxide, e.g. α,α′-bis(t-butylperoxy-m-isopropyl)benzene (PBP), to provide a thermoset. The PPE/TAIC mixture was shown to have the upper critical solution temperature (UCST) type phase behavior. At the single-phase regime above UCST and below the cure temperature (∼180°C for PBP), the mixture had a low viscosity, less viscous than a conventional thermoplastic such as PC and PP. That is, a nice window for injection molding was available, e.g., at 100°C to 160°C for a 50/50 blend. After injecting into a hot mold set at cure temperature, the blend cured in a short time (∼80% conversion in 5 min). Then the molded and partly cured material kept its shape and dimensions during post-cure in a hot chamber at higher temperature (e.g. 250°C). Using transmission electron microscopy and dynamic mechanical analyses, it was shown that the cured blend had a bicontinuous two-phase structure with periodic spacings of ∼30 nm, suggesting a structure formation via a spinodal decomposition driven by the increase in molecular weight of TAIC during cure. The cured material showed excellent flexural strength and high chemical resistance. 相似文献
99.
Inactivation of Bacillus spores by the combination of moderate heat and low hydrostatic pressure in ketchup and potage 总被引:2,自引:0,他引:2
Islam MS Inoue A Igura N Shimoda M Hayakawa I 《International journal of food microbiology》2006,107(2):124-130
The combination effect of moderate heat and low hydrostatic pressure (MHP) on the reduction of Bacillus subtilis, Bacillus coagulans and Geobacillus stearothermophilus spores in food materials (potage and ketchup) was investigated. These bacterial spores were suspended in potage (pH 7), acidified potage (pH 4), neutralized ketchup (pH 7) and ketchup (pH 4). The suspensions were treated with and without pressure (100 MPa) and temperatures of 65-85 degrees C for 3 to 12 h. The bacterial spores were inactivated by 4-8 log cycles during MHP treatment in potage, acidified potage and ketchup, whereas the spores were highly resistant to long time heat treatment in potage and neutralized ketchup. The degrees of spore destruction were mostly dependent on pH and medium composition during MHP treatment. The inactivation effect in MHP treatment was higher at the pH 7 than at pH 4 both in ketchup and potage. The bacterial spores showed higher inactivation in potage than ketchup during MHP treatment. 相似文献
100.
The alkyl derivatives of boehmite were prepared by solvothermal reaction of aluminum isopropoxide in n-alcohols (ethanol, 1-butanol, 1-hexanol, 1-octanol and 1-dodecanol) and the products were recovered as aerogel/xerogel by
the removal of the solvent at the end of reaction. Aerogel or xerogel can be obtained simply by using only a reaction vessel
(autoclave) and the obtained products were composed of plate-like particles having a well-developed boehmite structure. The
alumina powders obtained by calcination of these products had relatively large pore-volumes ranging from 1.35 to 2.56 cm3/g. Transformation into α-Al2O3 was retarded even after calcination at 1200 °C. The effect of n-alcohols used in the solvothermal reaction on the phase, morphology and pore-texture of the alumina samples are discussed. 相似文献