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41.
Hajime Masukawa Masaharu Kitashima Kazuhito Inoue Hidehiro Sakurai Robert P. Hausinger 《Ambio》2012,41(2):169-173
To mitigate global warming caused by burning fossil fuels, a renewable energy source available in large quantity is urgently required. We are proposing large-scale photobiological H2 production by mariculture-raised cyanobacteria where the microbes capture part of the huge amount of solar energy received on earth’s surface and use water as the source of electrons to reduce protons. The H2 production system is based on photosynthetic and nitrogenase activities of cyanobacteria, using uptake hydrogenase mutants that can accumulate H2 for extended periods even in the presence of evolved O2. This review summarizes our efforts to improve the rate of photobiological H2 production through genetic engineering. The challenges yet to be overcome to further increase the conversion efficiency of solar energy to H2 also are discussed. 相似文献
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Numerical investigation concerning the impact of CO2 geologic storage on regional groundwater flow 总被引:1,自引:0,他引:1
Hajime Yamamoto Keni Zhang Kenzi Karasaki Atsunao Marui Hitoshi Uehara Noriaki Nishikawa 《International Journal of Greenhouse Gas Control》2009,3(5):586-599
Large-scale storage of carbon dioxide in saline aquifers may cause considerable pressure perturbation and brine migration in deep rock formations, which may have a significant influence on the regional groundwater system. With the help of parallel computing techniques, we conducted a comprehensive, large-scale numerical simulation of CO2 geologic storage that predicts not only CO2 migration, but also its impact on regional groundwater flow. As a case study, a hypothetical industrial-scale CO2 injection in Tokyo Bay, which is surrounded by the most heavily industrialized area in Japan, was considered, and the impact of CO2 injection on near-surface aquifers was investigated, assuming relatively high seal-layer permeability (higher than 10 microdarcy). A regional hydrogeological model with an area of about 60 km × 70 km around Tokyo Bay was discretized into about 10 million gridblocks. To solve the high-resolution model efficiently, we used a parallelized multiphase flow simulator TOUGH2-MP/ECO2N on a world-class high performance supercomputer in Japan, the Earth Simulator. In this simulation, CO2 was injected into a storage aquifer at about 1 km depth under Tokyo Bay from 10 wells, at a total rate of 10 million tons/year for 100 years. Through the model, we can examine regional groundwater pressure buildup and groundwater migration to the land surface. The results suggest that even if containment of CO2 plume is ensured, pressure buildup on the order of a few bars can occur in the shallow confined aquifers over extensive regions, including urban inlands. 相似文献
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Masafumi Fujita Jumpei Suzuki Daisaku Sato Yuji Kuwahara Hiromune Yokoki Hajime Kayanne 《Sustainability Science》2013,8(3):381-390
Water pollution, evident by negative values of redox potential in waters, occurs at the lagoonal coast located near the densely populated area of Fongafale Islet on Funafuti Atoll, Tuvalu, Central Pacific. Sediment microbial quinone analysis revealed that these coastal sediments exhibit 2.7–10.4 times more microbial biomass, significantly different microbial community structure and low microbial diversity, when compared to an undisturbed natural coastal sediment. Thus, the pollution is chronic. By considering the total land use/coverage on the islet, the situation of septic tank installations, temporal changes in water redox potential and Escherichia coli numbers in the coastal waters and the spatial distribution of acid volatile sulfide in the sediments, we conclude that domestic wastewater is the primary source of pollution. This pollution is proposed to occur via the following mechanism: during ebb tides, domestic wastewater leaking from bottomless septic tanks and pit toilets run off into the lagoonal coast. Tide changes control the pollution load of domestic wastewater. 相似文献
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Jun Tabata Yutaka Narai Nobuo Sawamura Syuntaro Hiradate Hajime Sugie 《Die Naturwissenschaften》2012,99(7):567-574
Mealybugs, which include several agricultural pests, are small sap feeders covered with a powdery wax. They exhibit clear sexual dimorphism; males are winged but fragile and short lived, whereas females are windless and less mobile. Thus, sex pheromones emitted by females facilitate copulation and reproduction by serving as a key navigation tool for males. Although the structures of the hitherto known mealybug pheromones vary among species, they have a common structural motif; they are carboxylic esters of monoterpene alcohols with irregular non-head-to-tail linkages. However, in the present study, we isolated from the Matsumoto mealybug, Crisicoccus matsumotoi (Siraiwa), a pheromone with a completely different structure. Using gas chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy, we identified the pheromone as 3-methyl-3-butenyl 5-methylhexanoate. Its attractiveness to males was confirmed in a series of field trapping experiments involving comparison between the isolated natural product and a synthetic sample. This is the first report of a hemiterpene mealybug pheromone. In addition, the acid moiety (5-methylhexanoate) appears to be rare in insect pheromones. 相似文献
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Tohru Kamo Beili Wu Yuriko Egami Hajime Yasuda Hideki Nakagome 《Journal of Material Cycles and Waste Management》2011,13(1):50-55
Steam gasification in the presence of carbonate compounds is an effective method to recover useful materials from electronic
waste streams by converting plastics into gaseous products that can be used for energy production and avoiding the expensive
manual disassembly process. We investigated steam gasification of activated carbon in the presence of various mixtures of
lithium carbonate, sodium carbonate, and potassium carbonate. The activated carbon was almost completely converted into hydrogen
and carbon dioxide at 700°C under 0.1 MPa pressure in the presence of carbonate mixtures. Carbon dioxide was also derived
from partial decomposition of lithium carbonate. Steam gasification was accelerated in the presence of various carbonate mixtures
and at increasing steam partial pressures. These experimental results show that fluidity of carbonates, the potassium content
of the carbonate, and the steam partial pressure are important factors in accelerating steam gasification. 相似文献
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The first-order rate constants of 8 organic substances were measured using the ethyl nitrite and nitrogen dioxide photolyses and their relative rates with respect to n-hexane rate constant were calculated. These were compared with literature data. Relatively small photolysis rates of alkane and aromatics were shown for our photosystems and the alkenes were rapidly photolyzed. For mixed photooxidation reactions of various organics, it would be reasonable for organics of the group classified by their molecular structures to be discussed on their reactivities with OH radicals. 相似文献
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Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) formation by the thermal reactions of phenols with CuCl2 under oxygen flux were carried out in relation to their formation mechanisms. To evaluate the effect of photocatalytic degradation of titanium dioxide (TiO2) thin film prepared by the sol-gel method, the photocatalysis of PCDD/DFs in acetonitrile/water solution by batch-recycle system was conducted. For the thermal reaction system of powder mixtures of 2,4,5-trichlorophenol (2,4,5-TCP) and CuCl2, the formation rates were 8.1 microg/g-2,4,5-TCP/min for total PCDD/DFs and 6.9 microg/g-2,4,5-TCP/min for PCDDs, and total PCDD/DF rate was higher by approximately 40 fold compared to phenol vapor/oxygen/CuCl2 powder system. For the system of 2,4,5-TCP, PCDDs were mainly formed via ortho-phenoxyphenols (POP) intermediate by the condensation of 2,4,5-trichlorophenate. For PCDD/DF photocatalytic degradations, most PCDD congeners photodecomposed rapidly and the rates presented more than 70% (as dechlorination rates of 76% for PCDDs) at 24 h after irradiation, using PCDD/DFs formed with 2,4,5-TCP. The rate constants were in the order of 4.8-6.1 x 10(-3) min(-1), assuming the pseudo-first-order reactions for their low levels. 相似文献