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51.
Meng Zhang Xinkai Ding Weixiang Peng Hongliang Zhang Bingjie Wu 《Molecular simulation》2019,45(3):178-185
Radiation damage in reactor materials caused by the collision of the fast neutrons has a great impact on the reliability and safety of nuclear reactors. The element vanadium has attracted interest in many fields due to its advantageous properties in alloys. Thus, molecular dynamics simulation (MD) and first-principles calculation have been executed here to explore the radiation-resistant properties of five materials adding a layer in the bulk (pure iron and four types of Fe–V alloys containing 10%-40% V). The following results were inferred from these simulations. Firstly, the number of Frenkel pairs (FPs) at the stable quenching stage in the bulk decreases when the Fe–V alloy is added as an anti-radiation layer to the bulk. These benefits are evident for the Fe80V20 and alloy layers with more vanadium. The main reason is that the Fe–V binding energy is greater than the Fe-Fe binding energy, which can make the Primary Knock-On atom (PKA) lose more energy at the Fe–V alloy layer. Secondly, the average value of point-defect, cluster and defect clustered fractions in the bulk of Fe–V alloy is smaller than that in the pure iron at the stable quenching stage, especially for the Fe80V20 alloy. 相似文献
52.
Revegetation is a traditional practice widely used for soil and water conservation on the Loess Plateau in China. However, there has been a lack of reports on soil microbial–biochemical indices required for a comprehensive evaluation of the success of revegetation systems. In this study, we examined the effects of revegetation on major soil nutrients and microbial–biochemical properties in an artificial alfalfa grassland, an enclosed natural grassland, and an artificial shrubland (Caragana korshinskii), with an abandoned cropland as control. Results showed that at 0–5, 5–20, and 20–40 cm depths, soil organic carbon, alkaline extractable nitrogen and available potassium were higher in natural grassland and artificial shrubland compared with artificial grassland and abandoned cropland. Soil microbial biomass C (Cmic) and phosphorous (Pmic) substantially decreased with depth at all sites, and in abandoned cropland was significantly lower than those of natural grassland, artificial grassland, and artificial shrubland at the depth of 0–5 cm. Soil microbial biomass N (Nmic) was higher in artificial shrubland and abandoned cropland compared with that in natural and artificial grasslands. Both Cmic and Pmic were significantly different between the 23‐year‐old and the 13‐year‐old artificial shrublands at the 0–5 cm depth. The activities of soil invertase, urease, and alkaline phosphatase in natural grassland and artificial shrubland were higher than those in artificial grassland and abandoned cropland. This study demonstrated that the regeneration of both natural grassland and artificial shrubland effectively preserved and enhanced soil microbial biomass and major nutrient cycling, thus is an ecologically beneficial practice for recovery of degraded soils on the Loess Plateau. 相似文献
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Zhang Y Meng Q Jiang T Wang H Xie L Zhang R 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2003,135(1):43-54
Iron is one of the most important minor elements in the shell of bivalves. This study was designed to investigate the involvement of ferritin, the principal protein for iron storage, in shell formation. A novel ferritin cDNA from the pearl oyster (Pinctada fucata) was isolated and characterized. The ferritin cDNA encodes a 206 amino acid polypeptide, which shares high similarity with snail soma ferritin and the H-chains of mammalian ferritins. Oyster ferritin mRNA shows the highest level of expression in the mantle, the organ for shell formation. In situ hybridization analysis revealed that oyster ferritin mRNA is expressed at the highest level at the mantle fold, a region essential for metal accumulation and contributes to metal incorporation into the shell. Taken together, these results suggest that ferritin is involved in shell formation by iron storage. The identification and characterization of oyster ferritin also helps to further understand the structural and functional properties of molluscan ferritins. 相似文献
55.
A europium‐sensitized fluorescence spectrophotometry method using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS), was developed for the determination of gatifloxacin (GFLX). The GFLX–Eu3+–SDBS system was studied and it was found that SDBS significantly enhanced the fluorescence intensity of the GFLX–Eu3+ complex (about 25‐fold). The optimal experimental conditions were determined as follows: excitation and emission wavelengths of 338 and 617 nm, pH 7.5, 3.0 × 10–6 mol/L europium(III), and 5.0 × 10–5 mol/L SDBS. The enhanced fluorescence intensity of the system (ΔIf) showed a good linear relationship with the concentration of GFLX over the range 1.0 × 10–8–8.0 × 10–7 mol/L with a correlation coefficient of 0.9990. The detection limit (S:N = 3) was determined as 1.0 × 10–9 mol/L. This method has been successfully applied for the determination of GFLX in pharmaceuticals and human urine/serum samples. Compared with most other methods reported, the rapid and simple procedure proposed here offered higher sensitivity, wider linear range and good stability. The luminescence mechanism of the system is also discussed in detail. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
56.
MENG Yan ZHAO ChunYan ZHANG XueXin ZHAO HuaShan GUO LiRong Lü Bin ZHAO XueJian& YANG BaoXue Department of Pathophysiology School of Basic Medicine Jilin University Changchun China Department of Physiology Department of Medicine University of California San Francisco CA USA 《中国科学:生命科学英文版》2009,52(5):474-478
57.
马铃薯卷叶病毒基因间隔区的克隆及序列分析 总被引:6,自引:0,他引:6
根据已报道的马铃薯卷叶病毒基因组序列.设计合成一对特异性引物,以马铃薯卷叶病毒中国分离株(PLRV-Ch)的RNA为模板,反转录合成cDNA第一条链,经PCR扩增后克隆于pUC19质粒中,进一步用PCR鉴定、限制酶切分析和序列分析,结果表明:PLRV-Ch基因间隔区由197个核苷酸组成,与国外报道的荷兰PLRV-N加拿大PLRV-C,澳大利亚PLRV-A,苏格兰PLRV-S各株系核苷酸序列具有很高的同源性,同源率依次为99%、98%、93%、98%。 相似文献
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