Kinetic analysis of the factors limiting the output power of the Ne--CuBr UV laser

The parametric optimization of the Ne--CuBr UV laser excited by longitudinal pulsed discharge is analysed by using a self-consistent kinetic model. Consistent characteristics of the optimization process are obtained by comparing with the experimental results. Simulation results show that neon ions come into being along with considerable depletion of the ground-state copper atoms. And the optimization of the discharge tube diameter is the tradeoff between the specific output photon density and the total active volume. Both the optimal neon gas pressure and the optimal reservoir temperature result from the balance between the neon ion density and the ground-state copper atom density to arrive at a maximum of their product.     

Alternate oscillations of self-terminating and recombination lasers in univalent calcium and strontium ions

The univalent calcium and strontium ions have been confirmed as ideal lasing substances both for self-terminating laser and recombination laser by theoretically analysing their energy level structures and lasing mechanisms. With the optimization of the excitation circuit and the improvement of the laser cavity as well as the laser discharge tube, thealternate laser oscillatlons of the two laser mechanisms were suceessfully realized by longitudinal pulsed discharge in mixture vapours of helium and univalent ions of calcium or strontium, respectively. The dependences of laser performance on working parameters, together with the characteristics of the photoelectric pulse waveforms were elementally studied and analysed.     

脱氧核糖核酸的核磁共振研究简介

从NMR谱峰归属,NMR约束及结构计算,NMR谱的主要特征,化学位移的环流效应,以及溶液动力学等几个方面简要地介绍了核磁共振在DNA结构和动力学研究中的应用. 指出了DNA的NMR研究中存在着的一些问题. 这些问题主要包括：分子力场中的二面角参数不符合非规整DNA结构中的许多二面角;用分子模拟软件重建DNA结构时没有很好的重现性;DNA的化学位移环流效应理论尚未成熟;“无模型(model-free)”模型在定量解释异核稳态NOE时不理想. 然而,NMR所提供的结构和动力学信息仍然是十分重要的并且极大地深化了人们对DNA的了解.     

基于HIRFL-CSR中剥离器的支束线物理设计

介绍了通过剥离器后不同电荷态的束流在弯曲磁铁中的传输情况,由此引出一种切割束流的方法,在此基础上设计了一条支束线,以实现两个实验终端同时供束,增加供束时间.在束运线设计过程中,根据HIRFL CSR的实际条件,对束流的中心轨迹和束流包络做了详细的计算,给出了束流输运线的几何布局和各个元件的基本物理参数. A new branch beam line downstream of the stripper located between SFC and SSC is designed to collect the beams with the charge states other than the most intensive one. The layout of the branch beam line and the physical parameters for each dipole and quadrupole are given based on careful calculations.     

Cd(Ⅱ)和ATP的结合位点的NMR研究

用NMR方法研究了金属镉离子在ATP(嘌呤三磷酸腺苷)上的配位点.测量了不同pH值时由于Cd²⁺的存在而引起的¹H,¹⁵N及³¹P的化学位移和³¹P－³¹P中的偶合常数的变化以及由ATP的存在所引起的¹¹³Cd的化学位移的变化.结果表明,在pH＞4.5的条件下,ATP主要以磷酸根和N₇同时对Cd²⁺配位;在pH值2.5～4.5的条件下,ATP主要以磷酸根和N₁同时对Cd²⁺配位,还存在少量的磷酸根和N₇同时配位的模式;而在酸性非常强的条件下(pH＜2.5),ATP不再与Cd²⁺相互作用。     

十二烷基聚氧乙烯硫酸钠胶束体系的流变性质研究

用流变学方法研究了无机电解质KBr存在时,阴离子表面活性剂十二烷基聚氧乙烯(3)硫酸钠(SDES)水溶液中胶束的生长和结构。通过测量体系的稳态剪切粘度(η)和应力(σ)关系,得到零剪切粘度(η0)、复合粘度(|η^*|)、动态模量[储能模量(G')和损耗模量(G")、平台模量(G0)、结构松驰时间(τ)等流变学参数,并应用Cox-Merz规则和Cole-Cole图,发现在SDES/KBr体系中可以形成蠕虫状胶束网络结构,体系为假塑性流体,偏离Maxwell模型,具有非线性粘弹性,没有单一的结构松驰时间。     

31PNMR研究水生动物细胞死亡过程的动力学性质

由于细胞凋亡的研究有助于理解胚胎发育、免疫耐受、细胞群体稳定等重要生命现象, 并对治疗疾病具有潜在的价值, 故已成为研究的热点[1～5]. 已有文献报道, 细胞的死亡形式与细胞内ATP(三磷酸腺苷)的含量有关, 在细胞凋亡的过程中, 细胞内ATP的含量必须保持一定的水平[6,7]. 如在研究人的T-细胞死亡过程中, 发现当ATP的含量降低时, 细胞死亡的方式是坏死而不是凋亡[1,8]. 对于在细胞死亡过程中能量代谢物质的动态变化, Davis等[9]在对神经系统PC12细胞的凋亡过程的研究中发现, 尽管ATP的含量保持不变, 但Pi(无机磷)进入ATP和蛋白质的量明显减少, 进入磷酸肽的量明显增加. 以上结果表明, 可以利用31P NMR研究细胞的死亡过程. 本文首次利用31P NMR观测水生动物不同部位细胞死亡过程中ATP, PCr(磷酸肌酸), Pi和磷脂等能量代谢物质的含量变化并得到变化的速率常数, 所得结果有助于人们了解细胞死亡过程中能量代谢物质的变化规律和判断细胞死亡的快慢.     

Method of determining cosmological parameter ranges with samples of candles with an intrinsic distribution

In this paper, the effect of the intrinsic distribution of cosmological candles is investigated. We find that in the case of a narrow distribution the deviation of the observed modulus of sources from the expected central value can be estimated within a ceratin range. We thus introduce lower and upper limits of X², X _min² and X_max² to estimate cosmological parameters by applying the conventional minimizing X² method. We apply this method to a gamma-ray burst (GRB) sample as well as to a combined sample including this GRB sample and an SN Ia sample. Our analysis shows that: a) in the case of assuming an intrinsic distribution of candles of the GRB sample, the effect of the distribution is obvious and should not be neglected; b) taking into account this effect would lead to a poorer constraint of the cosmological parameter ranges. The analysis suggests that in the attempt of constraining the cosmological model with current GRB samples, the results tend to be worse than was previously anticipated if the mentioned intrinsic distribution does exist.     

用二维NMR交换谱定量地研究氘代DMSO和氘代氯仿中小肽活泼质子的交换动力学

用核磁共振二维交换谱方法研究了类肽化合物Cbz-Ser-Tyr-OC₆H₁₃中活泼质子的交换动力学,结果表明,在DMSO-d₆和CDCl₃溶液中,四种活泼质子与溶剂中残留水的交换快慢顺序为:Ser-OH > Tyr-OH > Ser-NH > Tyr-NH.在此基础上,对氨基酸中氨基所处的局部环境进行了讨论.     

碲杂冠醚及其铂配合物的合成

本文通过双(2-羟基乙基)碲醚与二醇的二对甲苯磺酸酯缩合, 首次合成了一类新型的冠醚-碲杂冠醚及其中一个碲杂冠醚与二氯化铂的配合物,并对碲杂冠醚的合成方法.结构特征以及配位性能等进行了讨论.