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271.
Inhibiting spontaneous light emission and redistributing the energy into useful forms are desirable objectives for advances in various fields, including photonics, illuminations, displays, solar cells, and even quantum-information systems. We demonstrate both the "inhibition" and "redistribution" of spontaneous light emission by using two-dimensional (2D) photonic crystals, in which the refractive index is changed two-dimensionally. The overall spontaneous emission rate is found to be reduced by a factor of 5 as a result of the 2D photonic bandgap effect. Simultaneously, the light energy is redistributed from the 2D plane to the direction normal to the photonic crystal. 相似文献
272.
Three-dimensional (3D) photonic crystals containing artificial point defects have been fabricated to emit light at optical communications wavelengths. They were constructed by stacking 0.7-micrometer-period gallium arsenide striped layers, resulting in a 3D "woodpile" photonic crystal. Indium-gallium arsenide-phosphide quantum-well layers emitting at a wavelength of 1.55 micrometers were incorporated in the center of the crystal. Samples having up to nine stacked layers were constructed, and artificial point-defect cavities of different sizes were formed in the light-emitting layer. Light emission was suppressed in the photonic crystal regions, whereas cavity modes were successfully observed at the point defects and were size dependent. 相似文献
273.
Summary Haploid plants (2n=12) were produced by anther culture from the tuber-bearing wild speciesS. verrucosum. 相似文献
274.
Vita Ratri Cahyani Jun Murase Eiji Ishibashi Susumu Asakawa Makoto Kimura 《Biology and Fertility of Soils》2009,45(4):337-346
We isolated manganous ion (Mn2+) oxidizing bacteria and fungi from Mn nodules collected from two Japanese rice fields. The phylogenetic position of the Mn-oxidizing
bacteria and fungi was determined based on their 16S rDNA and 18S rDNA sequences, respectively. Among 39 bacterial and 25
fungal isolates, Burkholderia and Acremonium strains were the most common and dominant Mn2+-oxidizing bacteria and fungi, respectively. Majority of the Mn-oxidizing bacteria and fungi isolated from the Mn nodules
belonged to the genera that had been isolated earlier from various environments. Manganese oxide depositions on Mn2+-containing agar media by these microorganisms proceeded after their colony developments, indicating that the energy produced
from Mn2+ oxidation is poorly used for microbial growth. 相似文献
275.
Vita Ratri CAHYANI Jun MURASE Susumu ASAKAWA Makoto KIMURA 《Soil Science and Plant Nutrition》2009,55(4):468-477
The present study examined T4-type phage communities in rice straw (RS) under the composting process by analyzing the composition of the major capsid gene ( g23 ) of T4-type bacteriophages. The g23 clones were obtained from RS throughout the composting process from RS materials to composting RS in the curing stage (for 124 days). Most of the g23 clones were phylogenetically closely related to those in rice field soils and rice field floodwaters, and Paddy Groups II and III appeared to characterize the g23 genes in the composting RS. The diversity of g23 genes in the composting RS was highest in the RS material (day 0 after the onset of composting) and in the early thermophilic stage (day 7), and decreased markedly in the middle and curing stages. This change was in contrast to that of the bacterial community, which showed higher diversity in the middle and curing stages. There was no specific clone that characterized any stage during the composting process. These findings indicate that the phage community is not the major controlling agent in determining eubacterial succession and that the thermophilic stage in the composting process efficiently annihilated T4-type phages in the composting pile. 相似文献
276.
The day–night change in fish community structure over a year was examined in a seagrass bed in Lake Notoro, Hokkaido, northern Japan, to examine nocturnal increases in predation risk. This seagrass bed has previously been considered a predation refuge for juvenile and small-sized fishes. Species richness, abundance and biomass of piscivorous fishes during nighttime were higher than those during daytime on all sample dates surveyed (May, August and November 2013), indicating an increase in predation risk for juvenile and small-sized fishes during nighttime. The mean biomass-weighted trophic level of fish communities in the seagrass bed was also higher at night than in the day. The piscivorous fishes collected in the seagrass bed during the night included important fishery species. These may obtain energy through nocturnal feeding in the seagrass bed. Therefore, the function of seagrass beds as fish habitats should be re-evaluated by considering two possible characteristics contributing to fishery production: as a daytime predation refuge for juvenile and small-sized fishes, and as a nighttime foraging ground for piscivorous fishes. 相似文献