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He离子注入的尖晶石中Au纳米颗粒的合成研究
No full text利用20 keV的He离子注入表面蒸镀了Au薄膜的尖晶石(MgAl2O4)样品,随后对注入样品进行了退火处理。在紫外可见光谱上观察到了由于金属纳米颗粒的存在而引起的较强的表面等离子体共振吸收峰,提供了材料中金属纳米颗粒形成的光谱证据。并对形成的Au纳米颗粒的尺寸随退火温度以及He注入剂量的变化进行了研究
沙生濒危物种霸王的高频植株再生研究
No full text实验选用霸王无菌苗的茎尖、子叶、下胚轴和胚根作为材料,研究霸王不同外植体的离体培养技术。结果表明,霸王茎尖是诱导丛生芽的良好外植体,而子叶、下胚轴和胚根是诱导愈伤组织的良好外植体;霸王茎尖的最适增殖培养基是:MS+6-BA 5.0 mg.L-1+NAA 1.0 mg.L-1;最适生根培养基是:MS+IAA 1.5 mg.L-1;最适愈伤组织诱导培养基是:MS+6-BA 1.0 mg.L-1或MS+6-BA 1.0 mg.L-1+NAA 0.5 mg.L-1。沙质基质为霸王组培苗过渡的最佳基质
碳离子辐射引起Hela细胞线粒体DNA 4977 bp的缺失
No full text背景:线粒体DNA4977bp缺失的累积对衰老的多细胞动物来说是一个显著的特征,同时也与各种肿瘤细胞的转移和凋亡有关。目前的研究已证明辐射可特异性地诱导此缺失的产生,有望将其作为新的DNA水平的辐射损伤生物剂量标记。目的:用聚合酶链反应方法检测碳离子辐射引起的Hela细胞线粒体DNA4977bp突变缺失,并观察碳离子辐射剂量及辐射时间与线粒体DNA4977bp缺失的相关性。设计、时间及地点:细胞DNA水平的对照实验,于2008-10/11在甘肃省兰州市近代物理研究所完成。材料:人宫颈癌细胞Hela细胞株。方法:Hela细胞经2～8Gy的碳离子辐射后,于2～24h各个时间点分别提取包含线粒体DNA的全基因组DNA,并用聚合酶链反应法扩增线粒体DNA4977bp缺失的特异片段,通过限制反应模板浓度和聚合酶链反应循环数的方法进行定性分析。主要观察指标:碳离子辐射剂量及辐射时间对线粒体DNA4977bp缺失的影响。结果:经2Gy辐照处理的Hela细胞在2,4,8,24h4个时间点的检测中均无聚合酶链反应阳性产物,8Gy辐照处理的Hela细胞在12,16,24h3个时间点可检测到线粒体DNA4977bp缺失,且随时间延长而累积。辐照后12hHela细胞在8Gy辐照处理后可检测到线粒体DNA4977bp缺失,辐照后16和24hHela细胞在6,8Gy辐照处理后可检测到线粒体DNA4977bp缺失。结论:碳离子辐射引起的Hela细胞线粒体DNA4977bp缺失存在剂量相关性,且其累计程度可能与辐射时间有关
Kinetic energies of C-n(+) (n <= 58) fragment ions produced by nanosecond laser impact on C-60
No full textLaser-induced fragmentation of C-60 has been studied using a time-of-flight mass spectrometric technique. The average kinetic energies of fragment ions C-n(+) (n <= 58) have been extracted from the measured full width at half maximum (FWHM) of ion beam profiles. The primary formation mechanism of small fragment ion C-n(+) (n < 30) is assumed to be a two-step fragmentation process: C60 sequential decay to unstable C-30(+) ion and the binary fission of C-30(+). Considering a second photo absorption process in the later part of laser pulse duration, good agreement is achieved between experiment and theoretical description of photoion formation. (C) 2009 Elsevier B. V. All rights reserved
Synthesis and magnetic characterization of nickel ferrite nanoparticles prepared by co-precipitation route
No full textMagnetic nanoparticles of nickel ferrite (NiFe2O4) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses confirmed the formation of single-phase nickel ferrite nanoparticles in the range 8-28 nm depending upon the annealing temperature of the samples during the synthesis. The size of the particles (d) was observed to be increasing linearly with annealing temperature of the sample while the coercivity with particle size goes through a maximum, peaking at similar to 11 nm and then decreases for larger particles. Typical blocking effects were observed below similar to 225 K for all the prepared samples. The superparamagnetic blocking temperature (T-B) was found to be increasing with increasing particle size that has been attributed to the increased effective anisotropy energy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins or dead/inert layer in these nanoparticles. (c) 2008 Elsevier B. V. All rights reserved.Material Science Group-II, Institute of Modern Physics, Chinese Academy of Sciences P. R. China
National Natural Science Foundation of China 10775161
10775162
10805062
West Light Foundation of Chinese Academy of Science
Low-lying non-normal parity states in B-8 measured by proton elastic scattering on Be-7
No full textA new measurement of proton resonance scattering on Be-7 was performed tip to the center-of-mass energy of 6.7 MeV using the low-energy RI beam facility CRIB (CNS Radioactive Ion Beam separator) at the Center for Nuclear Study of the University of Tokyo. The excitation function of Be-7 + p elastic scattering above 3.5 MeV was measured Successfully for the first time, providing important information about the resonance structure of the B-8 nucleus. The resonances are related to the reaction rate of Be-7(p.gamma)B-8. which is the key reaction in solar B-8 neutrino production. Evidence for the presence of two negative parity states is presented. One of them is a 2(-) state observed as a broad s-wave resonance, the existence of which had been questionable. Its possible effects on the determination of the astrophysical S-factor of Be-7(p.gamma)B-8 at solar energy are discussed. The other state had not been observed in previous measurements, and its spin and parity were determined as 1(-). (C) 2009 Elsevier B.V. All rights reserved.Young Scientists 1774013
Experimental study of two-proton correlated emission from S-29 excited states
No full textAn experiment of a S-29 beam bombarding a Au-197 target at an energy of 49.2 MeV/u has been performed to study the two-proton correlated emission from S-29 excited states. Complete-kinematics measurements were carried out in the experiment. The relative momentum, opening angle, and relative energy of two protons, as well as the invariant mass of the final system, were deduced by relativistic-kinematics reconstruction. The Si-27-p-p coincident events were picked out under strict conditions and the phenomenon of p-p correlations was observed among these events. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like He-2 cluster emission, three-body phase-space decay, and two-body sequential emission were taken into account. Associated with the Monte Carlo simulations, the present results show that two protons emitted from the excited states between 9.6 MeV and 10.4 MeV exhibit the features of He-2 cluster decay with a branching ratio of 29(-11)(+10)%.National Natural Science Foundation of China 10675169
10735100
10727505
Major State Basic Research Developing Program 2007CB81500
Measurement of the inelastic branch of the O-14(alpha, p)F-17 reaction: Implications for explosive burning in novae and x-ray bursters
No full textA measurement of the inelastic component of the key astrophysical resonance in the 14O(α,p)17F reaction for
burning and breakout from hot carbon-nitrogen-oxygen (CNO) cycles is reported. The inelastic component is
found to be comparable to the ground-state branch and will enhance the 14O(α,p)17F reaction rate. The current
results for the reaction rate confirm that the 14O(α,p)17F reaction is unlikely to contribute substantially to burning
and breakout from the CNO cycles under novae conditions. The reaction can, however, contribute strongly to the
breakout from the hot CNO cycles under the more extreme conditions found in x-ray bursters
电子束辐照紫花苜蓿愈伤组织后再生苗的RAPD分析
No full text<正>目的:利用RAPD技术研究了电子束辐照紫花苜蓿愈伤组织后引起苜蓿再生苗基因组DNA的变异,为电子束辐照诱变的分子机制研究提供理论依据
Radiative electron capture and subsequent radiative decay in collisions of U89+ ions with N-2
No full textTo evaluate the radiative electron capture for the collisions of U89+ ion with N-2, radiative recombination cross sections and the corresponding emitted photon energies are calculated from the ground state 1s(2)2s to 1s(2)2snl(j) (2 <= n <= 9, 0 <= l <= 6) using the newly developed relativistic radiative recombination program RERR06 based on the multiconfiguration Dirac-Fock method. The x-ray spectra for radiative electron capture in the collision have been obtained by convolving the radiative recombination cross sections and the Compton profile of N2. Good agreement is found between the calculated and experimental spectra. In addition, the transition energy levels and probabilities among the 147 levels from the captured 1s(2)2snl(j) have been calculated. From the calculated results, radiative decay cascade processes followed by the radiative electron capture have also been studied with the help of multistep model and coupled rate equations, respectively. The present results not only make us understand the details of the radiative electron captures and the radiative decay cascade spectra in the experiment but also show a more efficient way to obtain the cascade spectra. Finally, the equivalence between the multistep model and coupled rate equations has been shown under a proper condition and the latter can hopefully be extended to investigate other cascade processes