Y2O3 : Eu3+ microspheres: Solvothermal synthesis and luminescence properties

Y2O3 : Eu3+ microspheres, with an average diameter of 3 mu m, were successfully prepared through a large-scale and facile solvothermal method followed by a subsequent heat treatment. X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectra, thermogravimetric and differential thermal analysis, inductive coupled plasma atomic absorption spectrometric analysis, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra, as well kinetic decays, and cathodoluminescence spectra were used to characterize the samples. These microspheres were actually composed of randomly aggregated nanoparticles. The formation mechanisms for the Y2O3 : Eu3+ microspheres have been proposed on an isotropic growth mechanism. The Y2O3 : Eu3+ microspheres show a strong red emission corresponding to D-5(0) -> F-7(2) transition (610 nm) of Eu3+ under ultraviolet excitation (259 nm) and low-voltage electron beams excitation (1-5 kV), which have potential applications in fluorescent lamps and field emission displays.

Reduction from Eu3+ to Eu2+ in BaAl2O4 : Eu phosphor prepared in an oxidizing atmosphere and luminescent properties of BaAl2O4 : Eu

A reduction phenomenon of Eu3+ -> Eu2+ was observed for the first time when Eu3+ ions were doped into an AlO4-tetrahedron-containing compound BaAl2O4 in an oxidizing atmosphere of air by high-temperature solid-state reaction. X-ray powder diffraction patterns and photoluminescent spectra are used to confirm the compound structure and detect the simultaneous existence of both divalent and trivalent europium ions, respectively. The abnormal Eu3+ -> Eu2+ reduction is explained by a charge compensation model. Spectroscopic properties of BaAl2O4:Eu are discussed and Eu2+ emission spectrum shows consistence with the results reported by Katsumata et a]. [J. Cryst. Growth 198/199 (1999) 869.] and Lin et al. [Mater. Chem. Phys. 70 (2001) 156.].

The modification of screen-printed carbon electrodes with amino group and its application to construct a H2O2 biosensor

Electrooxidation of thionine on screen-printed carbon electrode gives rise to the modification of the surface with amino groups for the covalent immobilization of enzymes such as horseradish peroxidase (HRP). The biosensor was constructed using multilayer enzymes which covalently immobilized onto the surface of amino groups modified screen-printed carbon electrode using glutaraldehyde as a bifunctional reagent. The multilayer assemble of HRP has been characterized with the cyclic voltammetry and the faradaic impedance spectroscopy. The H2O2 biosensor exhibited a fast response (2 s) and low detection limit (0.5 muM).

Synthesis, crystal structure and reactivity of (2,4-C7H11)(2)Yb center dot DME

(2,4-C7H11)(2)Yb . DME was synthesized by the reaction of YbCl3 with K(2,4-C7H11)(2,4-dimethylpentadienyl potassium), and the single crystal X-ray diffraction showed that the complex exists in a cis- staggered conformation. Thf crystal of the compound belongs to the monoclinic space group P2(1)/n with a = 0.675 2 (1) nm, b = 1.490 6 (1) nm, c = 1.529 3 (2) nm, beta = 97.55 (2)degrees, V = 1.977 79 (4) nm(3), Z = 4, F(000) = 735.8 e, mu = 49.49 cm(-1), R = 0.033 and R-w = 0.032. The title complex can be used as a catalyst for the polymerization of methyl methacrylate (MMA).

Lamellar single crystals of nylon-10,10 crown from a dimethylformamide solution

A new solvent, dimethylformamide (DMF), and the traditional solvent, 1,4-butanediol, were used to prepare single crystals of nylon-10,10 from a dilute solution. The lamellae grown from DMF inhabited a more perfect structure and regular shape than those crystals crystallized from traditional solvents such as 1,4-butanediol and glycerin. These thin and perfect lamellar crystals demonstrated patterns of variation in spacing different from those of melt-crystallized spherulites on heating. Specifically, the two main spacings slightly separated rather than continuously approaching each other when the temperature was greater than 180 degreesC. This is a novel phenomenon observed in nylons. Nevertheless, the usual pattern of change in spacing was observed during the cooling process. These lamellar crystals showed more compact spacing of the (002) and (010/100) planes than spherulites at room temperature. (C) 2001 John Wiley & Sons, Inc.

主链玻璃化转变区在室温附近的梳形聚合物电解质

主链玻璃化转变区在室温附近的梳形聚合物电解质＊齐力林云青夏永姚王佛松（中国科学院长春应用化学研究所长春１３００２２）关键词梳状高分子，固体电解质，离子导电性，玻璃化转变，分子运动＊１９９４－１０－３０收稿；１９９５－１２－１０修稿７３２高分子固体电解...

掺锡三氧化二铟导电玻璃双工作电极薄层光透电化学池的设计

本文报道了ITO导电玻璃双工作电极薄层光透电化学池的设计。这种薄层池具有操作简便,成本低廉的特点,其突出优点在于工作电极的边际效应因采用辅助工作电极而得以明显消除。以Fe(CN)_6~(3-)/(4-)~考察了该池的电化学和光谱吸收响应特性。

Evolution and variation of the Tsushima warm current during the late Quaternary: Evidence from planktonic foraminifera, oxygen and carbon isotopes

The evolution and variation history of the Tsushima warm current during the late Quaternary was reconstructed based on the quantitative census data of planktonic foraminiferal fauna, together with oxygen and carbon isotope records of mixed layer dweller a ruber and thermocline dweller N. dutertrei in piston core CSH1 and core DGKS9603 collected separately from the Tsushima warm current and the Kuroshio dominated area. The result showed that the Tsushima warm current vanished in the lowstand period during 40-24 cal ka BP, while the Kuroshio still flowed across the Okinawa Trough, arousing strong upwelling in the northern Trough. Meanwhile, the influence of freshwater greatly increased in the northern Okinawa Trough, as the broad East China Sea continental shelf emerged. The freshwater reached its maximum during the last glacial maximum (LGM), when the upwelling obviously weakened for the lowest sea-level and the depression of the Kuroshio. The modern Tsushima warm current began its development since 16 cal ka BP, and the impact of the Kuroshio increased in the middle and northern Okinawa Trough synchronously during the deglaciation and gradually evolved as the main water source of the Tsushima current. The modern Tsushima current finally formed at about 8.5 cal ka BP, since then the circulation structure has been relatively stable. The water of the modern Tsushima current primarily came from the Kuroshio axis. A short-term wiggle of the current occurred at about 3 cal ka BP, probably for the influences from the enhancement of the winter monsoon and the depression of the Kuroshio. The cold water masses greatly strengthened during the wiggle.

牦牛放牧率和放牧季节对小嵩草高寒草甸土壤养分的影响

经过两年牦牛放牧试验表明,夏季草场不同土壤层有机质、有机碳、全磷、全氮和速效磷的含量及0～20cm土壤层营养因子的平均含量与放牧率呈线性回归关系,速效氮含量与放牧率呈二次回归关系;冬季草场不同土壤层有机质、有机碳和全氮与放牧率呈线性回归关系,全磷、速效磷和速效氮的含量及0～20cm土壤层营养因子的平均含量与放牧率呈二次回归关系。随着放牧率的逐渐增加,夏季草场不同土壤深度速效氮含量也逐渐减小,当放牧率达到1.07、1.08和1.22头·hm-2时,0～5、5～10、10～20cm土壤速效氮含量依此达到最小;冬季草场不同土壤层全磷、速效磷和速效氮含量逐渐增加,当放牧率达到0.81、0.78和1.00头·hm-2,1.03、1.09和1.03头·hm-2,1.36、1.35和1.30头·hm-2时,0～5、5～10、10～20cm土壤层全磷、速效磷和速效氮含量分别依此达到最大。在夏季草场,0～20cm土壤层速效氮平均含量达到最小放牧率是1.07头·hm-2;冬季草场0～20cm土壤层全磷、速效磷和速效氮含量达到最大放牧率分别是0.90、0.83和1.21头·hm-2。

模拟降水对高寒矮嵩草草甸群落影响的初步研究

通过野外控制实验，研究了高寒矮篙草草甸不同植物类群、群落对模拟增减降水条件下的响应。结果表明，不同植物类群(禾草类、莎草类)增加降水20％，地上生物量分别比对照提高103．63、77．12g／m^2。在植物生长期(6月)，增加降水20％及40％，植物群落物种多样性指数(H)分别比对照提高0．188和0．735；而均匀度指数(J)在增加降水40％时，提高了0．086。生长期(7月)增加降水20％，物种多样性指数(H)和均匀度指数(J)分别提高0．409和0．07。当降水增加20％时，植物群落中禾草类的重要值较对照提高了0．92。

高寒退化与未退化草甸土壤下匍匐茎鹅绒萎陵菜的克隆生长特征的比较

通过鹅绒萎陵菜的野外移栽试验，分析了在矮蒿草草甸土壤和退化草甸土壤下该种植物的克隆繁殖特征。结果表明，在母株产生的匍匐茎数量、母株高度和叶片大小在两类不同土壤下没有明显差异，母株叶片数、匍匐茎的粗度、匍匐茎长度以及间隔子的长度有较明显的差异。在退化草甸土壤中母株叶片较多，匍匐茎长度和间隔子长度明显较长，匍匐茎直径也明显较大。在退化草甸环境中，由于土壤养分相对较缺乏，鹅绒萎陵菜可能通过增加母株叶片的数量，尽可能多地积累光合产物，来保证匍匐茎的生长，匍匐茎也以增加粗度和增加长度来尽量增强其觅食能力。鹅绒萎陵菜在生物量投资分配上也表现出一定的差异。与退化草甸土壤环境相比，在未退化草甸土壤中，鹅绒委陵菜克隆母株和分株的生物量均明显偏向地下部分（根系）的投资，以期从土壤中吸收更多的养分，从而最终提高了株的成活率。

高寒矮蒿草草甸群落植物多样性和初级生产力对模拟降水的响应

通过野外控制实验,研究了高寒矮嵩草草甸群落植物多样性、初级生产力对模拟降雨条件的响应.结果表明:(1)在植物生长期(6月),增加降雨20%、增加降雨40%,植物群落物种多样性指数(H)和均匀度指数(J)分别比对照提高了0.188和0.011、0.735和0.076,生长期(7月)增加降雨20%物种H和J提高了0.409和0.07;(2)禾草类:增加降雨20%处理的地上生物量与对照相比没有明显的显著性差异(P＞0.05),增加降雨40%处理的地上生物量与对照相比差异显著(P＜0.05),说明过多增加降雨会抑制禾草的生长发育.杂类草:减少降雨50%处理的地上生物量与对照相比差异显著(P＜0.05),其地上生物量对减少降雨的反映比较敏感.莎草类:其地上生物量对增加和减少降雨都没有显著变化;(3)0～10 cm和0～30 cm土层地下生物量均在增加降雨20%时最高,地下生物量的总量也在增加降雨20%时最高;(4)矮嵩草草甸地下生物量与地上生物量、总生物量的比值接近于生长季末时最大,且在模拟增加降雨20%的水平时,7、8、9月份地下和地上生物量较其它处理组高.

一种多目标快速识别的图象处理方法研究

本文针对实时序列图像多目标识别问题提出了一种快速图象处理方法.该方法依据一定的先验知识和准则，对复杂背景图像进行窗口化，使用局部灰度自适应重新量化和最大精分割处理，实现了对全景视场内预定目标的快速准确提取和识别。为动态环境中多目标条件下移动机器人的视觉定位、导航和目标跟踪所需图像处理技术提供了一种新的方法。

金山金矿构造控矿特征及其模拟实验

在前人工作的基础上，研究金山金矿构造控制产出部位，控制金山金矿蚀变糜棱岩金矿和石英脉金矿体 及矿石类型，控制金山金矿微量元素、稀土元素、同位素及流体包裹体等地球化学特征；运用中国科学院地球 化学研究所矿床地球化学国家重点实验室中的构造地球化学(构造成矿)高温高压实验条件进行构造控矿模 拟实验，模拟高温高压条件下，岩石、矿石的变形实验，构造控制成矿物质活化、迁移聚集以及构造控制金山金 矿载金矿物成矿元素变化的模拟实验和多期多次构造应力作用下成矿物质活化、迁移模拟实验。实验结果表 明：构造活动的热动力作用下，不仅使岩石、矿石产生韧性剪切变形和脆性变形，并可看出韧性变形在前，脆性 变形在后，并叠加在韧性变形之上，构造作用能使成矿物质活化、迁移并聚集在襁皱虚脱部位，层问破碎带及 裂隙交汇部位；多期多次构造应力实验不仅使变形、破裂加剧，并使成矿物质叠加富集。实验结果与金山金矿 成矿十分近似，这不仅为研究金山金矿成矿和分布规律提供实验资料和依据，也为矿区进一步找矿提供有益 信息。