995 resultados para topic test
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We have investigated the performance of a EXOGAM-Segmented-Clover with 16 segments as a Compton polarimeter to measure the linear polarization of gamma rays. The polarization sensitivity of the Clover detector has been measured at the energy of 1332keV through the coincidence measurements of cascade gamma-rays from Co-60. Experimental values were in good accord with our expectation.We have investigated the performance of a EXOGAM-Segmented-Clover with 16 segments as a Compton polarimeter to measure the linear polarization of gamma rays. The polarization sensitivity of the Clover detector has been measured at the energy of 1332keV through the coincidence measurements of cascade gamma-rays from Co-60. Experimental values were in good accord with our expectation.
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The high charge state all permanent Electron Cyclotron Resonance Ion Source (ECRIS) LAPECR2 (Lanzhou All Permanent magnet ECR ion source No.2) has been successfully put on the 320kV HV platform at IMP and also has been connected with the successive LEBT system. This source is the largest and heaviest all permanent magnet ECRIS in the world. The maximum mirror field is 1.28T (without iron plug) and the effective plasma chamber volume is as large as circle divide 67mm x 255mm. It was designed to be operated at 14.5GHz and aimed to produce medium charge state and high charge state gaseous and also metallic ion beams. The source has already successfully delivered some intense gaseous ion beams to successive experimental terminals. This paper will give a brief overview of the basic features of this permanent magnet ECRIS. Then commissioning results of this source on the platform, the design of the extraction system together with the successive LEBT system will be presented.
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A recoil separator Wien-filter which was developed for the Radioactive Ion Beam Line in Lanzhou (RIBLL) as an extension is described. It consists of 2 quadruple triplets and a standard Wien-filter. It was designed for study of the fusion-evaporation reactions. The overall design, background suppression, the transmission efficiency, the angular acceptance and the momentum acceptance have been described. All the performances fulfil the designed requirements. Based on the test results, with some modifications the investigations of the nuclei with Z <= 110 and the drip-line nuclei in the medium-heavy mass region can be carried out with this facility.
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In order to expand the solid angle for imaging of electrons in ion-atom collisions, we designed a complex Helmholtz coils composed of four single coils. Theoretical simulations were carried out to optimize the arrangement of the coils. The complex is constructed according to the theoretical analysis, and the magnetic fields were measured for interested regions. The measured results show that the relative uniformity of the magnetic fields is +/- 0.6%, which satisfies the requirements of collision experiments.
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Charge stripping is employed to produce multi-charged ions for injecting the cooling storage ring After penetrating through the carbon foil, the widened distribution of ion charge states poses a limit to the ion injection Therefore, the carbon foil plays a key role in the charge snipping injection In this paper, foul strippers for Heavy Ion Research Facility at Lanzhou (HIRFL) and Cooling Sun age Ring (CSR) are introduced The charge state distribution of the stripped ions is measured and the stripping efficiency of the foils is investigated The experimental results are consistent with the theoretical values
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为测量重离子加速器冷却储存环(HIRFL-CSR)的外靶实验终端上不同能量的γ射线,一种用于探测γ射线的高能量分辨的探测装置正在中国科学院近代物理研究所建设,该探测器由中国科学院近代物理研究所自行生长的铊激活的碘化铯CsI(Tl)晶体组成。与日本Hamamatsu公司生产的S8664-1010型雪崩光二极管(APD)耦合,测试其光输出的非均匀性和能量分辨,从测试结果给出了所需CsI(Tl)晶体合格的标准。目前已完成该γ探测球计划的六分之一,所提供的晶体合格率达94%以上。
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In the construction of a large area neutron detector (neutron wall) that is used to detect neutrons at GeV energies, the performances of all the sampling paddle modules prepared for the neutron wall are investigated with a specially designed test bench. Tested by cosmic rays, an average intrinsic time resolution of 222.5 ps is achieved at the center of the modules. The light attenuation length and the effective speed of the light in the module are also investigated.
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Chinese Academy of Sciences (ISCAS)
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Association for Computing Machinery, ACM; IEEE; IEEE Computer Society; SIGSOFT
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A novel "gold electrode-molecular wires-silver" junction was facilely fabricated for electrochemical study on the electron transportation through molecular wires. Rapid electron transportation through this sandwich-like structure was indeed observed by cyclic voltammograms and ac impedance measurements. Since rather reproducible and reliable results are easily available by electrochemical techniques, it would be an efficient and reliable test bed for electrochemical investigation of charge transportation through molecular wires in self-assembled monolayers on electrodes.
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种质问题是养殖健康发展的基础。在鱼类养殖中,卵子和精子的质量直接关系到受精、胚胎发育,仔稚鱼发育以及幼鱼生长等一系列过程。本论文针对大西洋庸鲽和大西洋鲑的配子质量进行研究。研究内容涉及大西洋庸鲽精子冷冻保存方法;促性腺激素释放激素类似物(GnRHa)使用对其精子冷冻保存效果、以及脂肪酸组成的影响;野生和驯养大西洋鲑卵子在脂肪酸、类胡萝卜素、矿物盐方面的差异比较。 精子冷冻保存通过提高对精子的利用效率,进而对于种质改良,推进鱼类养殖科研和生产具有重要意义。本实验建立了大西洋庸鲽精子大容量冷冻保存方法。八种抗冻剂冷冻保存实验结果表明:10% 及15% DMSO配以 HBSS 或KS 的抗冻剂组合冷冻保存效果最佳,4 mL体积冷冻保存可获得与1.6 mL同样的保存效果。 在繁殖季节后期注射GnRHa激素缓释剂,可获得质量稳定的大西洋庸鲽精液,将激素注射方法与精子冷冻保存方法相结合对于提高雄鱼利用率,扩大生产规模具有重要实用价值。本项研究分三个时间采集注射GnRHa激素后的雄鱼精子以及同期未注射激素的雄鱼精子,对所有精子样品使用同样的方法进行冷冻保存,检测冷冻保存后解冻精子的受精率与活力。结果表明,激素注射与否对于冷冻保存后精子的受精率和活力无显著影响,两类冷冻精液均达到鲜精水平。实验结果还表明,注射激素14天后的精子的密度显著的降低。说明GnRHa激素的使用可以显著降低精子密度,但不会影响精子的冷冻保存效果。 本相研究同时对注射GnRHa 缓释激素和未注射GnRHa 缓释激素的大西洋庸鲽精液脂肪酸成分进行分析,以检测该激素使用对精子生化组分的影响。结果表明激素的使用对在DHA (22:6n-3,二十二碳六烯酸)、EPA(20:5n-3,二十碳五烯酸)、AA(20:4n-6,花生四烯酸)等重要脂肪酸,不饱和脂肪酸、饱和脂肪酸以及n-3、n-6等重要种类的脂肪酸总量及其比例没有显著影响。精液脂肪酸中DHA含量最高,约占25%;PUFA约为44%。 作为世界性的重要养殖品种,野生和驯养大西洋鲑在形态、生化组成以及遗传 等方面表现出的差异被广泛关注。本论文,对野生和驯养大西洋鲑受精卵关键生化成分进行分析,通过与野生受精卵比较阐明驯养受精卵的质量状况,为亲鱼营养需求提供指导依据。本实验中野生配子和驯养配子的受精率没有显著差异,但重要脂肪酸组成、类胡萝卜素以及矿物盐含量都存在多方面显著差异。两类受精卵脂肪酸中含量最高的依次为18:1n-9(油酸)、DHA(二十二碳六烯酸)、16:0(棕榈酸)、EPA(二十碳五烯酸)。野生受精卵的单不饱和脂肪酸总量显著高于驯养受精卵,而多不饱和脂肪酸(PUFA)比例显著低于驯养的受精卵。在主要必需不饱和脂肪酸(EFA)中,DHA和EPA在野生受精卵中的比例高于驯养受精卵,AA(花生四烯酸)低于驯养受精卵。野生受精卵虾青素(Ax)的含量低于驯养受精卵而鸡油菌素(Cx)含量高于驯养受精卵。野生受精卵中多种矿物盐的含量(铝、铜、铁、硒和锌)含量显著高于驯养的受精卵。差别最大的为铜。诸多方面的差异表明,野生亲鱼与驯养亲鱼产出的卵子确实存在显著差异,因此关注亲鱼的营养极为重要。
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In "high nitrate, low chlorophyll" (HNLC) ocean regions, iron has been typically regarded as the limiting factor for phytoplankton production. This "iron hypothesis" needs to be tested in various oceanic environments to understand the role of iron in marine biological and biogeochemical processes. In this paper, three in vitro iron enrichment experiments were performed in Prydz Bay and at the Polar Front north of the Ross Sea, to study the role of iron on phytoplankton production. At the Polar Front of Ross Sea, iron addition significantly (P < 0.05, Student's t-test) stimulated phytoplankton growth. In Prydz Bay, however, both the iron treatments and the controls showed rapid phytoplankton growth, and no significant effect (P > 0.05, Student's t-test) as a consequence of iron addition was observed. These results confirmed the limiting role of iron in the Ross Sea and indicated that iron was not the primary factor limiting phytoplankton growth in Prydz Bay. Because the light environment for phytoplankton was enhanced in experimental bottles, light was assumed to be responsible for the rapid growth of phytoplankton in all treatments and to be the limiting factor controlling field phytoplankton growth in Prydz Bay. During the incubation experiments, nutrient consumption ratios also changed with the physiological status and the growth phases of phytoplankton cells. When phytoplankton growth was stimulated by iron addition, N was the first and Si was the last nutrient which absorption enhanced. The Si/N and Si/P consumption ratios of phytoplankton in the stationary and decay phases were significantly higher than those of rapidly growing phytoplankton. These findings were helpful for studies of the marine ecosystem and biogeochemistry in Prydz Bay, and were also valuable for biogeochemical studies of carbon and nutrients in various marine environments.