排序方式: 共有7条查询结果,搜索用时 203 毫秒
1
1.
Absorption of nitrogen dioxide (NO(2)) by various broad-leaved tree species was determined by the (15)N dilution method. The tree seedlings were continuously exposed to 0.3 ppm (microl litre(-1)) NO(2) or the mixture of 0.3 ppm NO(2) and 0.1 ppm O(3) for 30 days. The total amount of NO(2)-nitrogen absorbed by a seedling during the 30-day exposure period primarily depended on the size of the seedling. Among the tested tree species, three cultivars of Populus showed the highest rate of NO(2) absorption per unit leaf area, reaching as much as 0.3 mg N per dm(2) per day. The absorption rates for Populus cultivars were more than four times greater than those for Viburnum or Cinnamomum which had the lowest rate. A highly significant correlation was recognised between the rate of NO(2) absorption and the stomatal conductance among the species. Three cultivars of Populus which had the highest rates of NO(2) absorption were most susceptible to the mixture of NO(2) and O(3). On the contrary, Cinnamomum, Viburnum and Quercus, which showed the lowest rate of NO(2) absorption, were very tolerant to the mixed gas. These results indicate that the species difference in susceptibility to the mixture of NO(2) and O(3) was mainly determined by the difference in rate of absorption of these gases. Exposure to NO(2) alone had no detrimental effect on the tested tree species. 相似文献
2.
Qingrong Qian Motoi Machida Masami Aikawa Hideki Tatsumoto 《Journal of Material Cycles and Waste Management》2008,10(1):53-61
Activated carbons were prepared from cattle manure compost (CMC) by ZnCl2 activation with various ZnCl2/CMC mass ratios. Based on the N2 adsorption-desorption isotherms, mathematical models including the Dubinin-Radushkevich (DR) equation, the αs plot, and the Horvath-Kawazoe method were used to analyze the pore structural characteristics of the prepared activated carbons.
It was found that for carbons possessing both micro-and mesopores, the DR method provided a more accurate estimation than
the αs method for the extent of microporosity. The effect of the ZnCl2 impregnation ratio on the pore structure was discussed using the DR method. The results revealed that pore evolution involved
three distinct regions with increases in the amount of impregnated ZnCl2: raising the ZnCl2/CMC mass ratio from 0.00 to 0.50 resulted in a 19-fold increase in micropore volume (Vme
D) but caused no change in the mesopore volume (Vme
D); increasing the ZnCl2/CMC mass ratio from 0.50 to 1.00 led to an increment in Vmi
D of about 50% and in Vme
D of 170%; while raising the ratio from 1.50 to 2.50 caused a slight decrease in Vmi
D but a 200% increment in the value of Vme
D. 相似文献
3.
Portions of the mitochondrial genome (ca. 4 kb), encoding three protein-coding (COI, ND4L, ND6) and two ribosomal RNA (srRNA,
lrRNA) genes, were sequenced for all six currently recognized species, plus one form, of the pelagic calanoid copepod genus
Neocalanus. In Neocalanus gracilis, the ND6 gene was not found in the sequenced portion of the mitochondrial genome. Unambiguously aligned sequences were subjected
to Bayesian, maximum-likelihood, maximum-parsimony, and neighbor-joining analyses using Eucalanus bungii as an outgroup. The resultant tree topologies from these four methods were congruent, robust, and all nodes were supported
by high bootstrap values and posterior probabilities of 92–100%. Two tropical and subtropical species (N. gracilis and N. robustior) occupied the most basal position, and a subantarctic (N. tonsus) and three subarctic Pacific species (N. cristatus, N. plumchrus, and N. flemingeri) diverged subsequently. Transequatorial dispersal of the ancestral population during glaciations is suggested for this pattern
of speciation, in which sister clades exhibited antitropical distributions. Although the area of ocean is much broader in
the subantarctic than the subarctic Pacific, a higher number of species occur in the subarctic Pacific (three) than the subantarctic
(one). The possibility that marginal seas, such as Japan Sea and Okhotsk Sea, function as natal areas for the divergence of
species is discussed. 相似文献
4.
Yoshimasa Amano Yusuke Sakai Takumi Sekiy Kimitaka Takey Kazuo Taki Motoi Machida 《环境科学学报(英文版)》2010,22(11):1666-1673
Tega-numa (Lake Tega) is one of the eutrophic lakes in Japan. For the improvement of water quality in Lake Tega, the Northchiba
Water Conveyance Channel was constructed in 2000, which transfer water from Tone River into the lake. After 2000, the
dominant species of diatoms, mainly Cyclotella sp., have been replacing blue-green algae, mainly Microcystis aeruginosa in Lake
Tega. This transition of dominant species would be due to the dilution, but the detail mechanism has not been understood yet. This
study examined the relationship between phosphorus fluctuation caused by river water dilution to Lake Tega and dominance of algal
species, M. aeruginosa or Cyclotella sp. based on the single-species and the mixed-species culture experiments. The single-species
culture experiment showed that the half-saturation constant and uptake rate of phosphorus were one order lower and seven times higher
for M. aeruginosa than those for Cyclotella sp. These findings implied that M. aeruginosa would possess a potential for the growth
and survival over Cyclotella sp. in the phosphorus limited condition. The superiority of M. aeruginosa was reflected in the outcome of
the mixed-species culture experiment, i.e., dominance of M. aeruginosa, even phosphorus concentration was lowered to 0.01 mg-P/L.
Therefore, it could be concluded that the decrease in phosphorus concentration due to the river water dilution to Lake Tega would be
interpreted as a minor factor for the transition of dominant species from M. aeruginosa to Cyclotella sp. 相似文献
5.
Takeda Yohei Okuyama Yuko Nakano Hiroto Yaoita Yasunori Machida Koich Ogawa Haruko Imai Kunitoshi 《Food and environmental virology》2020,12(1):9-19
Food and Environmental Virology - Influenza A virus (IAV) infection is perennially one of the leading causes of death worldwide. Effective therapy and vaccination are needed to control viral... 相似文献
6.
R. Dallai M. Gottardo D. Mercati R. Machida Y. Mashimo Y. Matsumura R. G. Beutel 《Die Naturwissenschaften》2013,100(6):581-594
A remarkable external sperm transfer is described for the first time in a species of a group of winged insects (Pterygota), the enigmatic Zoraptera. Mating and sperm transfer of two species of the order were examined in detail, documented, and compared with each other and with patterns described for other species belonging to the order. The behavior differs strikingly in Zorotypus impolitus and Zorotypus magnicaudelli. A copula is performed by males and females of the latter, as it is also the case in other zorapteran species and generally in pterygote insects. In striking contrast to this, males of Z. impolitus do not copulate but deposit small (100 μm in diameter) spermatophores externally on the abdomen of the female. Each spermatophore contains only one giant spermatozoon (3 mm long and 3 μm wide), a unique feature in the entire Hexapoda. External sperm transfer in Pterygota is a highly unusual case of evolutionary reversal. The very small relict group Zoraptera displays a uniform general morphology but exhibits very different reproductive structures and patterns of mating behavior. This may be an extreme form of a more general situation in insects, with a specific form of selection resulting in an accelerated rate of evolution in the reproductive system. 相似文献
7.
Two activated carbons (ACs) prepared from cattle manure compost (CMC) by ZnCl(2) activation were selected and out-gassed in a helium flow at various temperatures for 2h. The pore structure and surface chemical properties of the two selected ACs and their out-gassing treated ACs were characterized using N(2) adsorption-desorption, elements analysis, SEM and Boehm titration. A basic dye, methylene blue (MB), was chosen as an adsorbate to investigate the adsorption capacity for organic contaminant onto the activated carbons. It was found that the out-gassing treatment at 400 degrees C had little effect on the textural characteristics of the carbons but significantly changed the surface chemical properties such as surface functional groups concentration, pH and pH(PZC). The CMC-based activated carbons exhibited excellent performance for MB adsorption due to their high surface area, large mesopore volume and high nitrogen content. The kinetics of MB adsorption onto the activated carbons followed a pseudo-second-order equation, and the equilibrium data agreed well with the Langmuir model under the experimental conditions. The highest adsorption rate constant of k(ad) and the largest adsorption capacity of q(m) were found be 1.44x10(-4)g/mgmin and 519mg/g, respectively. The results suggested that the CMC-based activated carbons were effective adsorbents for the removal of methylene blue from aqueous solution. 相似文献
1