Simulation and analysis of 13N+p elastic resonance scattering

The 13N+p elastic resonance scattering has been studied at the secondary radioactive beam facility of CIAE in inverse kinematics via a thick-target method. The excitation function for the 13N(p,p) scattering was obtained in the energy interval of Ecm ≈0.5--3.2 MeV with a 13N secondary beam of (47.8±1.5) MeV. Carefulanalysis of the secondary beam components and extensive Monte-Carlo simulations enable the resolution of the experimental proton spectra. The resonance parameters for five low-lying levels in 140 were deduced by R- matrix fitting calculations with MULTI7 and SAMMY-M6-BETA. The present results show general agreement with those from a recent similar work, and thus confirm the observation of a new 0- level at 5.7 MeV in 14O with an improved width of 400(45) keV.     

在Armijo型线搜索下共轭梯度法簇的全局收敛性

本文我们讨论了一簇共轭梯度法，它可被看作是FR法和DY法的凸组合．我们提出了两种Armijo型线搜索，并在这两种线搜索下，讨论了共轭梯度法簇的全局收敛性．     

Structure and Photoluminescence of Polycrystalline MgxZn1-xO Films

Different photoluminescence （PL） spectra are observed for rf magnetron sputtered polycrystalline Mg0.25Zn0.75O and Mg0.37Zn0.63O films on silicon substrates when excited by different wavelengths. When the excitation wavelength is 280nm, a UV emission peak at 370nm and a blue peak at 462nm are generated for the Mg0.25Zn0.75O film, and those two peaks for the Mg0.37Zn0.63O film shift to 366nm and 466nm, respectively. The wavelengths of the PL peaks are related to the excitation wavelength. The stronger peak is obtained in the blue band due to a large number of oxygen vacancies caused by excess Zn and Mg atoms, while the weaker peak is obtained in the ultraviolet band.     

实用化MgB2超导材料研究进展

本文综述了实用化MgB2超导材料的最新研究进展．最新的理论和实验结果表明通过元素替代和掺杂，有希望进一步提高MgB2超导线带材的临界电流密度和磁通钉扎特性，完全可以达到实用化要求．目前MgB2超导磁体的制备技术研究已经开始，极有可能开发出采用闭路循环制冷机制冷的核磁共振成像仪（MRI）取代现在医学上使用的基于低温超导的核磁共振成像系统．     

紫外分光光度法测定蜂蜜中四环素和羟甲基糠醛

养蜂行业中,使用不当或过量使用四环素会导致其在蜂产品残留,对人类健康构成威胁,具体表现在对人的肠胃、肾脏、皮肤和骨骼,尤其是对儿童牙齿损害最大[1].     

FOX-12制备过程的反应机理及动力学

采用量子化学计算方法, 在B3LYP/6-311G(d,p)水平上研究了N-脒基脲二硝基酰胺盐(FOX-12)制备过程的反应机理. 优化得到了反应势能面上各稳定点的几何构型, 通过内禀反应坐标(IRC)确认了反应物、 中间体、 过渡态及产物之间的相关性. 为了得到更可靠的反应能量和势能面信息, 进一步在MP2/6-311++G(3df,3pd)水平上对得到的构型进行能量校正, 结果表明, 先取代磺酸基通道(A1)和先取代氢通道(B)都能生成二硝基酰胺酸(HDN), 其中通道A为主反应通道; HDN可以通过HDN→FOX-12与HDN→ADN→FOX-12 两种途径转化为目标产物FOX-12, 而第2种途径为较优途径. 应用经典过渡态理论(TST)与变分过渡态理论(CVT)以及小曲率隧道效应模型校正的变分过渡态理论(CVT/SCT)计算了在200~400 K范围内各反应通道相关基元反应的速率常数, 提供了在上述温度区间内的三参数Arrhenius关系式.     

荧光分光光度法分析天然水中铝形态的研究

基于衍生试剂与天然水中原生有机质之间对铝的竞争配位,建立了用荧光分光光度法区分天然水中铝形态的方法。以铬蓝黑R和桑色素为分析试剂可以测定无机单核铝,而以8-羟基喹啉为分析试剂则可以测定总单核铝,实验结果与用Driscoll方法所得到的结果基本一致。为有目的地选择分析试剂,在天然水自身pH条件下进行铝形态的直接分析提供了一个新的方法选择。相对来说,荧光分光光度法操作更加简单,条件温和,对原始样品几乎没有扰动,天然水中铝形态分析的结果更符合真实情况。     

T形截面振子的流致振动特性试验研究

近年来人们将流致振动(FIV)作为一种新的能源利用手段,针对圆柱型振子开展了较多的研究。随着研究的深入,发现异型截面振子因振动特性不同于圆柱型振子而具有更好的能量汲取特性。本文利用自循环水槽进行T形截面振子流致振动特性试验研究,对比研究T形振子与圆柱振子的流致振动响应差异,分析其能量捕获能力的优劣及适用范围,以期揭示阻尼比对T形振子的振动特性的影响。结果表明:不同于圆形截面振子,T形截面振子的振动表现为"非自限制"特性,出现驰振分支;增大阻尼会抑制T形截面振子的振动与驰振发生的可能性;相对于圆柱型振子而言,T形振子更适用于大流速下的能量汲取。     

10Be中子谱因子的实验研究

核谱因子描述了单粒子轨道中核子的占有状态,在核结构和核天体物理中有重要的应用。目前国际上10Be中子谱因子的研究结果存在3倍左右的差异。本实验利用中国原子能科学研究院HI-13串列加速器的高灵敏度Q3D磁谱仪,对13C（9Be,10Be）12C反应角分布进行了精确测量。通过实验数据和扭曲波玻恩近似（DWBA）计算结果进行比较,导出了10Be的中子谱因子。该结果与转动不变壳模型理论及曾敏尔等的评价结果基本一致。利用该结果可以得到9Be（n,γ）10Be的天体物理反应率,评价该反应在相关天体环境中对CNO循环种子核12C的影响,为核结构和核天体物理提供可靠数据。Spectroscopic factor describes the overlap between the initial and final states and gives some information on the occupancy of a given single-particle orbiting around nuclear. It plays an important role in a variety of topics on nuclear structure and nuclear astrophysics. Nowadays, several experiments have been performed to study the neutron spectroscopic factor of 10Be, but the results have a big difference with each other. In order to clarify this discrepancy, new measurement is highly needed. In this work, the angular distribution of 13C(9Be,10Be)12C reaction was measured at the Q3D magnetic spectrometer of the HI-13 tandem accelerator, China Institute of Atomic Energy, Beijing. And then, the neutron spectroscopic factor of 10Be was derived by normalizing the calculational differential cross-sections with the distorted-wave Born approximation to the experimental data. The present value is in good agreement with that obtained by Tsang et al. and also in good agreement with that derived from translationary invariant shell model calculation. One can use this result to calculate the 9Be(n, γ)10Be reaction rates and calculate its influence to the production of 12C.