加速器高频D电路Q值的计算与测量

介绍了回旋加速器高频单D型盒D电路Q值的计算与测量方法。重点对Q值的理论计算进行推导,并对计算原理进行说明。然后对计算结果和测量结果进行比较。得出的计算和测量结果基本吻合。误差产生的主要原因是计算过程中的近似和短路片接触电阻的取值,其中短路片接触电阻是一个重要因素,在设计腔体时应引起足够的重视。

Injection by hydrostatic pressure in conjunction with electrokinetic force on a microfluidic chip

A simple method was developed for injecting a sample on a cross-form microfluidic chip by means of hydrostatic pressure combined with electrokinetic forces. The hydrostatic pressure was generated simply by adjusting the liquid level in different reservoirs without any additional driven equipment such as a pump. Two dispensing strategies using a floating injection and a gated injection, coupled with hydrostatic pressure loading, were tested. The fluorescence observation verified the feasibility of hydrostatic pressure loading in the separation of a mixture of fluorescein sodium salt and fluorescein isothiocyanate. This method was proved to be effective in leading cells to a separation channel for single cell analysis.

额济纳天然绿洲景观演化驱动因子分析

额济纳天然绿洲位于我国西北干旱内陆河流域黑河流域下游 ,近年来 ,随着黑河中、上游地区下泄地表径流量的减少 ,额济纳天然绿洲景观退化严重。基于研究区近十几年来的景观演化总体特征 ,分别从气候因素、水文因素、人类干扰因素等几个主要的景观变化驱动因子入手 ,探讨其演化机制、揭示其演化规律。研究结果表明 :黑河流域中、上游下泄地表径流量的锐减而导致研究区地下水水位下降、地下水矿化度升高以及水质恶化是额济纳天然绿洲景观发生退化的根本原因 ,绿洲人类活动强度的增加、绿洲关键区域的超载和过牧以及蒸发度指数的升高、湿润系数的下降均加剧了研究区景观退化的程度。

塔叶苔属(SchiffneriaSteph.)(Hepaticae)的研究

塔叶苔属(Schiffneria Steph.)建立于1894年。作者在研究中国标本时,发现一新种———Schiffneria yunnanensis C.Gao& W.Li sp.nov.。塔叶苔属的配子体为叶状体,生殖枝具茎叶返祖现象,应置于叶苔亚纲的叶状体无组织分化类群———带叶苔目(Pallaviciniales)之中。

A versatile color tuning strategy for iridium(III) and platinum(II) electrophosphors by shifting the charge-transfer states with an electron-deficient core

By fusing an electron-deficient ring system with the phenyl ring of a 2-phenylpyridine (ppy)-type ligand, a new and synthetically versatile strategy for the phosphorescence color tuning of cyclometalated iridium(III) and platinum(II) metallophosphors has been established. Two robust red electrophosphors with enhanced electron-injection/electron-transporting features were prepared by using an electron-trapping fluoren-9-one chromophore in the ligand design. The thermal, photophysical, redox and electrophosphorescent properties of these complexes are reported. These exciting results can be attributed to a switch of the metal-to-ligand charge-transfer (MLCT) character of the transition from the pyridyl groups in the traditional Ir-III or Pt-II ppy-type complexes to the electron-deficient ring core, and the spectral assignments corroborate well with the electrochemical data as well as the timedependent density functional theory (TD-DFT) calculations. The electron-withdrawing character of the fused ring results in much more stable MLCT states, inducing a substantial red-shift of the triplet emission energy from yellow to red for the Ir-III complex and even green to red for the PtII counterpart.

THE SYNTHESES CHARACTERIZATION AND CRYSTAL-STRUCTURE OF RARE-EARTH COMPLEXES WITH L-PROLIN

The complexes of Ln(L-Pro)s(H2O)2(ClO4)3(Ln = Pr, Nd and Er. L-Pro = L-Proline) were synthesized and characterized by elemental analysis, IR. spectra and thermal analysis. The singal crystal Pr2(L-Pro)6(H2O)4(ClO4)6 Was also obtained. The crystal belongs to monoclinic, P2(1), a = 0.9879 (3) nm, b = 2.1883 (4) nm, c = 1.3393 (2)nm, beta = 91.23(2)-degrees, V = 2.895(1) nm3, Z = 2. R = 0.035 for 5032 observed reflections. The coordination polyhedron of Pr(III) ion comprises six oxygen atoms from L-Pro molecules and two water molecules. Each L-Pro molecule coordinates to two Pr(III) ions through its carboxyl group which serves as a bridging bidentate ligand to form onedimensional chain structure.

THE EFFECT OF RADIATION-INDUCED CROSS-LINKING ON THE RELAXATION OF TAUT TIE MOLECULES DURING ANNEALING OF DRAWN LDPE

Shrinkage, retractive stress, and infrared dichroism of the drawn low-density polyethylene (LDPE) as-drawn and irradiated by Co-60-ray have been measured under different annealing conditions. The shrinkage and the disorientation of the irradiated sample was undergone more rapidly than that of unirradiated one as the temperature was continuously increased, surpassing a certain value, and a higher degree of shrinkage and disorientation was achieved finally for the irradiated sample when the samples were annealed with free ends. For the samples heated isothermally with fixed ends, the retractive stress went through a maximum and then attenuated to a limited value, and the degree of such a stress attenuation for the unirradiated sample was much more than that for the irradiated sample. These results show that the taut tie molecules (TTMs) in drawn PE can relax by the pulling of chain segments out of crystal blocks that they anchored in at elevated temperatures higher than the a transition and also by the displacing of microfibrils if the samples were annealed with free ends. The cross-links produced by irradiation prohibit the former process. It was further observed that the dependence of the average extinction coefficient of the band at 2016 cm-1 on that of the band at 1894 cm-1 is related to irradiation and annealing conditions, which has also been explained by the relaxation of TTMs and the function of irradiation-induced cross-linking on the relaxation.

稀土与L-脯氨酸配合物的合成、表征及晶体结构

本文合成了通式为Ln(L-Pro)_3(H_2O)_2(ClO_4)_3(Ln=Pr、Nd、Er,L-Pro=L-脯氨酸)的固体配合物.元素分析、红外光谱、热分析对配合物进行了表征.培养了镨脯氨酸配合物的单晶,X射线四圓衍射确定了晶体的结构.晶体属于单斜晶系、空间群P2_1,α=0.9879(3),b=2.1883(4),c=1.3393(2)nm,β=91.23(2)°,V=2.895(1)nm~3,Z=2.晶体中每一个镨原子与来自6个L-脯氨酸羧基上的6个氧原子和2个结晶水分子键合,形成了一个八配位的稍有畸变的三角十二面体.每一个L-脯氨酸分子以羧基双齿方式与两个镨离子配位,形成了一个无限长的链状结构.

A comparative study of thermolysis characteristics and kinetics of seaweeds and fir wood

Thermal analysis and thermolysis kinetics of three kinds of seaweeds and fir wood (M. glyptostriboides Huet Cheng), a kind of typical land plant, had been conducted. The results showed that thermal stability follows the order of Grateloupia filicina < Ulva lactuca < Dictyopteris divaricata < fir wood. A notable difference on heat flow between seaweeds and fir wood during thermolysis was that the former were mainly connected with exothermic processes at relatively lower temperature regimes. while the latter was connected with an apparent endotherm at a relatively higher temperature regime followed by a maximum exothermic peak. This suggested that the heat coupling might be realized if co-thermolysis of seaweeds and fir wood were carried out. The main devolatilization phase of each seaweed could be described by Avrami-Erofeev equation, which indicated that thermolysis of seaweeds follows the mechanism of random nucleation and nuclei growth, whereas that of fir wood by Z-L-T equation and its thermolysis mechanism was three-dimensional diffusion. The activation energies calculated for both seaweeds and fir wood increase as conversion increases. However, those for the former have wider distribution. (c) 2006 Elsevier Ltd. All rights reserved.

Additional pandaloid shrimps from the South China Sea (Crustacea : Decapoda : Caridea), with description of one new species

The present paper reports 22 pandaloid shrimp species from the South China Sea and its adjacent area, including two new records of the South China Sea, 14 new records of the Nanshan Islands, and one new speices. Heterocarpus chani, new species, type localities from the Philippines and Nansha Islands, is distinguished from its allied species, H. gibbosus Bate, 1888, H. tricarinatus Alcock & Anderson, 1894 and H. lepidus De Man, 1917, by the third maxilliped with a short rudimentary exopod.