Investigation on preparation and fluorescence properties of oxy-fluoride glass co-doped with Er3+ and Yb3+

The glass sample based on the composition of 45PbF(2)-45GeO(2)-10WO(3) co-doped with Yb3+/Er3+ was prepared by the fusion method in two steps: melted at 950 degreesC for 20 similar to 25 min then annealed at 380 degreesC for 4 h. Through the V-prism it is found that the refractive index of host glass and the sample are 1.517 and 1.65 respectively. The transmittance was observed by using the ultraviolet-visible-infrared spectrometer in the wavelength range from 0.35 to 2.5mum. The transmittaitce of the host glass is beyond 73%. That of the sample is beyond 50% and there are characteristic absorption peaks of rare-earth ions. The emission spectrum was measured by using the Hitachi F-4500 fluorescent spectrometer pumped by 980 nm semiconductor laser. There are a strong emission peak at 530 nm and a weak peak at 650 nm.

Up-conversion spectrum properties of the oxy-fluoride glass co-doped with Er3+ and Yb3+

Up-conversion of 45PbF(2)-45GeO(2)-10WO(3) oxy-fluoride glasses co-doped with Yb3+ and Er3+ ions were prepared by fusion method through melting at 1223 K and then annealing at 653 K for 4 h. Transmittance of the undoped host glass was beyond 73% in a range of 0.6-2.5 mu m and the co-doped glasses still provided good transmittance beyond 50%. Refractive indices of the host and co-doped glasses were 1.517 and 1.650, respectively. Blue, green and red fluorescence spectra were observed in a range of 400-700 nm under 980 nm diode laser excitation. Up-conversion spectra at about 410, 518, 530and 650 nm were assigned to the 4f electron transitions of H-2(9/2) -> I-4(15)/(2), H-2(15/2) -> I-4(15/2) S-4(3/2) -> I-4(15/2) and F-4(9/2) -> I-4(15/2) of Er3+ ion, respectively. The mechanism of energy transfer between Yb3+ and Er3+ ions in the glass was analyzed. Raman shift shows the non-radiative relaxation of the glass sample is low.

Polyimides from isomeric biphenyltetracarboxylic dianhydrides and the effects of chemical structure on solubility

A series of homopolyimides and copolyimides was synthesized by the solution condensation of biphenyltetracarboxylic dianhydride (BPDA) isomers and various diamines followed by chemical imidization. These polyimides had intermediate to high molecular weights with inherent viscosities of 0.34-1.01 dL/g for homopolyimides and 0.48-1.02 dL/g for copolyimides. Thermogravimetric analysis indicated that the aromatic polyimides were stable up to 500degreesC, and the 5% weight loss temperatures were recorded in the range of 506-597degreesC in an air atmosphere and in the range of 517-601degreesC in a nitrogen atmosphere, depending on the diamines used. The glass transition temperatures of aromatic homopolyimides were above 271degreesC, while the glass transition temperatures of the copolyimides increased with an increase in the 2, 2', 3, 3'-BPDA-component. The effects of the chemical structure of the polymer chain on the solubility were investigated. It was found that the solubility of BPDA-based polyimides could be improved by the introduction of flexible units, nonlinear and non-coplanar units, and copolymerization. The polyimides with nonlinear and non-coplanar units derived from 2, 2', 3, 3'-BPDA appeared to have prominently enhanced solubility in polar aprotic solvents and polychlorocarbons when compared with the homopolyimide derived from 3, 3', 4, 4'-BPDA.

铂、钌共修饰的氧化钛电极对甲醇的电催化氧化

首次发现用电化学阴极还原 -阳极氧化法制得的 Pt-Ti Ox/Ti和 Pt-Ru-Ti Ox/Ti电极对甲醇氧化呈现出较高的电催化活性和稳定性 ,其中 Pt-Ru-Ti Ox/Ti电极比 Pt-Ti Ox/Ti电极具有更好的性能 .实验结果表明 ,这两种电极对甲醇氧化具有高电催化活性是由于 Pt、Ru得到了较好的分散 ,较好的稳定性可归结于Pt、Ru与 Ti Ox 协同作用导致弱的 CO吸附而使电极不易中毒 .

Syntheses and structures of Na-2[Zn-II(ida)(2)].7H(2)O and Na-4[Hg-II(nta)(2)].7H(2)O

The title complexes were synthesized and the crystal structures of their salts were determined by single-crystal X-ray structure analyses. Na-2[Zn-I(ida)(2)]. 7H(2)O: Triclinic, P1, a=0.523 4(2) nm, b=0.897 10(10) nm, c=1.069 10(10) nm, alpha=85.910(10)degrees, beta= 76.380(10)degrees, gamma=83.52(2)degrees, V=0.484 2(2) nm(3), Z=1. The complex anion [Zn-I (ida)(2)](2-) has a pseudo-octahedral structure in which the two N atoms: are in a trans configuration. Na-4[Hg-I(nta)(2)]. 7H(2)O: Monoclinic, C-c, a = 1.795 0(4) nm, b = 0.892 9(2)nm, c = 1.575 4(2) nm, beta = 92.78 (3)degrees, V = 2.526 2(9) nm(3), Z = 4. The complex anion [Hg-I (nta)(2)](4-) has a pseudo-bicapped-octahedral structure in which the two N atoms are in a trans configuration.

Na_2[Zn~Ⅱ(ida)_2]·7H_2O和Na_4[Hg~Ⅱ(nta)_2]·7H_2O的合成及结构测定

金属离子ＺｎⅡ和ＨｇⅡ分别是生物体必需的微量元素和对人体有害的毒性金属．如何有效地摄取ＺｎⅡ和排除ＨｇⅡ一直是化学家感兴趣的研究课题．而ＺｎⅡ和ＨｇⅡ能与各种氨基酸形成配合物，由于它们处于同一族，电子结构都是ｄ１０，故其配位结构只取决于金属离子半径的…

液/液界面电化学分析在双水相萃取中的应用

用循环伏安法(CV)研究了聚乙二醇(PEG)-6000/磷酸钾(K_3PO_4)双水相体系中各种组分对麦迪霉素推动质子在水/硝基苯(W/NB)界面上转移行为的影响.用液/液界面电化学分析技术检测了麦迪霉素在双水相体系中的分配情况,发现了麦迪霉素在双水相体系中的选择性分配,其分配系数大于44.测定的线性范围为50～800μg/mL,回收率大于93%.

INVESTIGATION OF PHASE SEPARATION BEHAVIOR IN POLY (METHYL METHACRYLATE)/POLY (STYRENE-CO-ACRYLONITRILE) MIXTURES WITH PULSED NUCLEAR MAGNETIC RESONANCE

Thermally induced phase separation in the mixture of poly (methyl methacrylate) (PMMA) with poly(styrene-co-acrylonitite (SAN) has intern studied with pulsed nuclear magnetic resonance(NMR) in single spin-lattice retaxation time T-1 of the eornpatibl. mixture two T-1 corresponding to those of PM MA-rich and SAN-rich comairis. Meanwhile, both T-1 gradually changing with annealing time provides the direct evidence that the phase separation takes place with a decomposition mechanism. Diffusion coeffieient was to lac negative, indicating an uphal diffusion characteristics, The basic parameters governing its kinetics were estimated using NMR date which were in good agreement with those evaluated from time-resolved light scattering experiments for a 60/40(PMMA/SAN) mixture annealed at 180.0 degrees C.

聚甲基丙烯酸甲酯与苯乙烯-丙烯腈共聚物混合体系相分离初期的固体NMR研究

本文用氢谱宽线固体NMR技术研究了聚甲基丙烯酸甲酯(PMMA)和苯乙烯-丙烯腈共聚物(SAN)混合体系不稳相分离初期阶段,得到了在分相过程中弛豫谱的变化规律,测定了相分离增长速率。结果指出:随着退火时间的增加,两相体系形成;大分子扩散方式是由浓度低的区域向浓度高的区域扩散,扩散系数为负值;相分离增长速率的数量级与用光散射研究的结果相同;分子相互作用的相关距离为46.5nm。

国产画眉草亚族叶表皮微形态特征及其在属间关系上的意义

通过国产画眉草亚族叶片表皮的解剖观察,结合外部形态,对该亚族内6个属的属间关系进行了分析.结果表明:羽穗草属应是国产画眉草亚族中最原始的类群,最高级的类群仍数细画眉草属,而其余4属即画眉草属、弯穗草属、尖稃草属和镰稃草属的演化水平居于两者之间;画眉草属和弯穗草属可能直接起源于原始的羽穗草属,而较高级的尖稃草属和镰稃草属又可能直接起源于较原始的画眉草属,并在镰稃草属的基础上进而派生了最进化的细画眉草属.整个研究结果既弥补了前人演化理论的不足,又为今后族进化的全面探讨提供了参考.

唐古特大黄叶柄的营养成分分析

对唐古特大黄植物地上部分基生和茎生叶柄的常规营养成分及维生素C、氨基酸、无机元素和有机酸进行了分析，结果表明，叶柄蛋白质含量较高，为5.84%，氨基酸组成全面，含量丰富；含有丰富的人体必需无机元素和较高含量的苹果酸。

车辆检测毫米波雷达信号处理技术研究

道路交通信息采集在智能交通系统中，担负着提供准确可靠的信息源以使整个智能交通系统得以顺利准确运行的重任。毫米波雷达交通检测器作为获取路面信息的一种方式，因其特有的优势具有广阔的应用前景。本论文是围绕一个基于毫米波雷达的车辆检测系统的研究课题进行的。 本文的主要工作及创新之处在于： (1) 结合毫米波车辆检测雷达的应用背景，首先阐述毫米波车辆检测雷达在智能交通系统中的应用，介绍了智能交通系统中路面信息采集各种不同方式的优缺点，同时给出采用毫米波车辆检测雷达系统进行交通信息采集的优越性和必要性，说明了本文的选题背景及主要研究内容。 (2) 针对毫米波车辆检测雷达的具体应用需要，在提出车辆检测雷达的工作原理，阐述毫米波车辆检测雷达的系统构成和整体框架结构之后，分别从系统硬件设计与实现、数字脉冲压缩原理和基于一维距离像的车辆目标识别三个方面进行阐述。根据实际应用提出了车辆检测雷达系统的性能技术参数要求，确定了系统实际的工作频段和工作体制，分析了线性调频系统的组成原理，对系统主要参数进行了定量计算和误差估计。 (3) 分析了几种简单形状目标的散射特性，对典型车辆的雷达截面积进行了粗略的工程估算。对宽带雷达杂波特性进行了分析，采用幅度为韦布尔分布、功率谱为高斯分布的杂波模型I模拟地杂波，幅度为瑞利分布、功率谱为高斯分布的杂波模型II来模拟气象杂波。 (4) 介绍了一维距离像的基本概念和获得一维距离像的方法，深入分析了一维距离像的基本特性。通过对基于位置信息的全程相关检测方法和基于能量积累的几种滑窗检测方法的比较，分析了它们在宽带雷达信号检测中的性能特点和应用条件。在此基础上，提出了一种适合宽带雷达的检测方法，即相邻脉冲重复周期相关检测(IPCD)方法。当采用多脉冲积累后，其检测能力比能量相加脉间非相干积累EAD检测平均提高2dB。

云南澜沧老厂大型银铅锌多金属矿床地质地球化学特征

通过对老厂银铅锌多金属矿床地质地球化学特征的系统总结，并与相关海相火山岩块状硫化物矿床的对比，认为矿床期后岩浆热液叠加特征明姓，矿体直接容矿围岩为火山-沉积岩，矿床属火山．沉积岩容矿的块状硫化物矿床。为介于典型的火山岩容矿的块状硫化物矿床（VHMS）和典型沉积岩容矿的海底喷气沉积矿床（SEDEX）之间的过渡类型，其矿化特征与新疆可可塔勒铅锌矿床（伊比利亚型）相类似.