Luminescence and energy transfer phenomena of several rare earth ions in the CaAl2B2O7

The luminescence properties of Ce3+, Gd3+, and Tb3+ have been investigated in the compound CaAl2B2O7. The single excitation band peaking at about 320 nm and single emission band peaking at about 384 nm for Ce3+, without the characteristic doublet, are attributed to the extensive crystal-field splitting of 4f ground state. The emission of Gd3+ consists of well-known sharp lines and two weak bands around 319.5 and 325 nm. These bands are due to the coupling of Gd3+ with BO33- groups. The green emission of Tb3+ is considerably sensitized by Ce3+. Energy transfer from Ce3+ to Tb3+ in CaAl2B2O7 is efficient. (C) 1997 Elsevier Science Ltd.

The fabrication of dipped CdS and sputtered ITO thin films for photovoltaic solar cells

Stable bilayer thin films of indium tin oxide (ITO) on CdS and CdS on ITO were formed for the window material of solar cells by chemical bath and sputtering methods. Scanning electron microscopy and X-ray diffraction studies have shown that both the ITO and CdS films are continuous, homogeneous, with high compactness. Measurement of the CdS film thickness across the 2 x 4 cm(2) reveals the good uniformity of these films. Four-point probe measurements show that the resistivity of a CdS film on an ITO surface is much better than that of the single CdS film The thermal stability of an ITO/CdS bilayer, interfacial reaction and optical transmittance were investigated at different annealing temperatures and environments (air, vacuum and N-2 + H-2). The results showed that the ITO/CdS bilayer film is a good window material for the CuInSe2 and CdTe cells. It is a simple method using a small amount of the cadmium compound.

STRUCTURE AND PROPERTIES OF POLYVINYL-ALCOHOL AMIDOXIME CHELATE FIBER

Polyvinyl alcohol amidoxime (PVAAO) chelate fiber prepared in our laboratory is a good adsorbent. Comparing with other adsorbents, it has many advantages, such as higher hydrophilicity, better adsorbability and easier synthesis. In this work, the synthesi

PHASE-BEHAVIOR IN THERMOTROPIC LIQUID-CRYSTALLINE POLYMER AND POLYARYLETHERSULFONE BLENDS

An experimental study of the phase morphology and miscibility of binary blends of poly-arylethersulfone (PES) and a liquid crystalline polymer (LCP) of p-oxybenzoate and ethylene terephthalate units in a 60/40 molar ratio (PET-60PHB) is described. Blends

晶体热膨胀与化学键的关系

本文建立了晶体线膨胀系数与化学键参数的经验关系:α=A(RN)/Zexp(Bfi)(其中 A、B 为常数,R 为键长,N 为配位数,Z 为电价,f_i 为离子性)。运用于碱金属卤化物、碱土金属硫族化合物的计算结果与实测值相一致;运用于其它二元晶体也得到合理的结果。另外对热膨胀其它影响因素也作了讨论。

含Eu~(3+)复合钛钽氧化物的研究

研究了TiO_2-Ta_2O_5-Li_2O:Eu~3+体系,当化学通式为Ti_(1-4x-y)Ta_(3x)Li_xO_2:Eu_y~(3+),在0.1≤y≤0.25,0.05

本征及掺杂态聚甲苯胺能带结构计算

本文通过聚(o~-,m~-)甲苯胺本征态及掺杂态共五种模型电子能带的计算,讨论了聚(o~-,m~-)甲苯胺的导电机制,认为聚甲苯胺中主要的载流子为共振的极化子。在计算中将聚甲苯胺视为准一维体系,采用EHMO-CO半经验计算方法。

浓水溶液的膜蒸馏行为——Ⅱ.蒸气压下降和透析作用的影响

膜蒸馏的蒸馏通量随溶液浓度的增加而逐渐降低,其实质是传质分数和组件的蒸馏效率随浓度增大而下降。本文近似地计算了理论传质分数,实际透过分数和组件的蒸馏效率在不同温度条件下的变化情况以及浓度变化对它们的影响,从中分析了浓溶液的蒸气压下降对膜蒸馏的影响,讨论了膜蒸馏过程中因渗透压而产生的透析现象的存在以及透析现象对膜蒸馏的干扰作用。

Cloning and expression of glucose regulated protein 78 (GRP78) in Fenneropenaeus chinensis

GRP78 (78 kDa glucose-regulated protein), also known as BiP (immunoglobulin heavy-chain-binding protein), is an essential regulator of endoplasmic reticulum (ER) homeostasis because of its multiple functions in protein folding, ER calcium binding, and controlling of the activation of transmembrane ER stress sensors. In this report, we cloned the full length cDNA of GRP78 (FcGRP78) from Chinese shrimp Fenneropenaeus chinensis. This cDNA revealed a 2,325 bp with 1,968 bp open reading frame encoding 655 amino acids. This is the first reported GRP78 gene in Crustacea. The deduced amino acid sequence of FcGRP78 shared high identity with previously reported insect GRP78s: 86, 87 and 85% identity with GRP78s of Drosophila melanogaster, Aedes aegypti and Bombyx mori, respectively. Northern blot analysis shows that FcGRP78 is ubiquitously expressed in tissues of shrimp. Heat shock at 35A degrees C significantly enhanced the expression of FcGRP78 at the first hour, reached the maximum at 4 h post heat shock, dropped after that and resumed to the normal level until 48 h of post recovery at 25A degrees C. Additionally, differential expression of FcGRP78 was detected in haemocytes, hepatopancreas and lymphoid organ when shrimp were challenged by white spot syndrome virus (WSSV). We inferred that FcGRP78 may play important roles in chaperoning, protein folding and immune function of shrimp.

Screening of salt tolerant watercress variants on natural seawater contained medium

The responses of stem segments of watercress (Nasturtium officinale R. Br.) to 6-BA,NAA and 2,4-D were studied. MS medium supplemented with 2.0 mg/L 6-BA, 0.2 mg/L 2,4-D was used for callus initiation and maintenance. MS medium supplemented with 4.0 mg/L 6-BA was suitable for plant regeneration and MS medium without plant hormone supplement was used for rooting and plant propagation. For screening of salt tolerant calli, stem segments of watercress were plated onto callus initiation medium containing 1/3 natural seawater. Seventeen out of the 325 plated explants produced calli. The growth curves demonstrated that the growth rate of salt-tolerant calli on saline medium almost matched that of the control calli on normal medium. Some of the salt-tolerant calli were transferred to the normal regeneration medium or saline regeneration medium to induce plant regeneration. In the first case, buds and shoots were regenerated in the same way as those of control calli on normal regeneration medium. More than 1 000 regenerated shoots were obtained of which 83 regenerated shoots were cut and transferred to saline MS base medium. At first, all shoot growth was inhibited, but 40 days after the transfer, rapid-growing axillary shoots were observed on 16 of the original shoots but none on the control shoots on saline MS base medium. Moreover, green spots appeared on most calli 10 days after they were transferred to saline medium, however buds appeared only on 5 calli from the 30 transferred calli and at the end only 2 rapid-growing shoots were obtained from two calli. In total, 18 variant lines were obtained through. propagation of the salt-tolerant shoots on saline MS base medium. RAPD analysis was performed in 10 of the 18 salt-tolerant variant lines and DNA variation was detected in all the tested variant lines.

On two species of euxanthine crabs from the South China Sea, including a description of a new species of Crosnierius (Crustacea : Decapoda : Brachyura : Xanthidae)

A new species of the previously monotypic xanthid genus Crosnierius Serene & Vadon, 1981 is described from the South China Sea. The species differs from Crosnierius carinatus Serene & Vadon, 1981 in the structure of the anterolateral teeth, ambulatory leg proportions and form of the male first pleopod. Paramedaeus planifrons (Sakai, 1965) is also reported from the South China Sea, the first record of the species outside its type locality of Japan.

牦牛的分类学地位及起源研究:mtDNA D-loop序列的分析

牦牛的起源与属级分类学地位至今仍然存在一定的争议.我们测定了家养牦牛和野生牦牛线粒体控制区(D-loop)序列,并以此构建牦牛和牛属、野牛属、水牛属以及非洲水牛属相关种的系统发育树.研究结果表明线粒体D-loop区与Cyt b基因序列在构建牛族的系统发育具有同样重要的价值.系统发育关系显示野牛属的灭绝种草原野牛与现存种美洲野牛先聚合为一单系群,然后再和牦牛形成一单系分支,表明牦牛与野牛属的草原野牛、美洲野牛亲缘关系最近,具有最近的共同祖先,而与牛属的其它亚洲物种亲缘关系较远.因此,本研究不支持将牦牛独立为牦牛属--Poephagus,牛属与野牛属在分类上也应合并为一个属.基于上述研究结果和化石证据,我们进一步对牦牛起源的历史背景进行了讨论,认为牦牛与野牛属的分化是由于第四纪气候变化在欧亚大陆发生的,野牛通过白令陆桥进入北美;冰期结束后,由于欧亚大陆其它地区温度升高,牦牛只能局限分布在较为寒冷的青藏高原;而野牛属在北美先后分化为草原野牛和美洲野牛,前者可能是后者的直接祖先.

唐古特大黄乙醇提取物的HPLC指纹图谱研究

用高效液相色谱法建立唐古特大黄乙醇提取物的指纹图谱分析方法.采用Phenomenex Kromasil C_(18)色谱柱(4.6mm×250mm, 5μm);甲醇 - 0.1% H_3PO_4为流动相,梯度洗脱,检测波长为270nm,以大黄酸为参照峰.结果共有18个共有峰.此法为有效地控制唐古特大黄乙醇提取物的质量提供了依据.