A Continuous-Time Random Walk Extension of the Gillis Model

We consider a continuous-time random walk which is the generalization, by means of the introduction of waiting periods on sites, of the one-dimensional non-homogeneous random walk with a position-dependent drift known in the mathematical literature as Gillis random walk. This modified stochastic process allows to significantly change local, non-local and transport properties in the presence of heavy-tailed waiting-time distributions lacking the first moment: we provide here exact results concerning hitting times, first-time events, survival probabilities, occupation times, the moments spectrum and the statistics of records. Specifically, normal diffusion gives way to subdiffusion and we are witnessing the breaking of ergodicity. Furthermore we also test our theoretical predictions with numerical simulations.     

镧与镍共沉积的研究

由于含稀土的合金新材料具有多种特殊功能，因此，其制备技术已为人们所关注．制备含稀土合金的方法有高温烧结法、真空蒸发法、离子溅射法及电化学法等．其中电化学法设备简单，容易获得不同组份的表层材料，但是，由于稀土元素的电位很负，从电解质水溶液中沉积稀土及其合金是相当困难的，以往曾有采用熔融盐电解质或非水电解质制备稀土合金的一些报导[1，2]，而从电解质水溶液中电沉积稀土合金的报导甚少．本研究采用适宜的络合剂，实现了从电解质水溶液中电沉积Ni－La合金，镀层中钠含量最高达22．58％（质量分数，下同）．通过XPS及…     

中国不同类型土壤中稀土元素的形态分布特征

采用中子活化分析地中国不同地带土壤中的稀土元素含量分布模型及其赋存形态进行了系统的研究。结果表明，黄棕壤，褐土，淋溶黑钙土及白浆土中稀土元素的分布均为轻稀土富集，Ｅｕ亏损型，砖红壤，红壤为轻稀土富集，Ｃｅ亏损型。     

稀土-二甲酚橙络合物的胶束液相色谱分离与测定

本文应用一种新的高效液相色谱-胶束液相色谱法,在Shim-Pack CLC-ODS(150mm×6.0mm)色谱柱上,用含1.6×10~(-2)mol/L的CTMAB和pH=7.40的三-(羟甲基)-氨基甲烷缓冲液的甲醇/水(5:95)作流动相,对15种稀土元素-二甲盼橙络合物进行分离,取得了较满意的结果。     

天冬酰胺Schiff碱稀土配合物的合成、表征与抗O-·2性能

合成了天冬酰胺－邻香草醛Schiff碱稀土配合物，用元素分析，摩尔电导率，磁化率测定，差热分析，红外与紫外光谱，1H NMR谱等手段对配合物进行了组成与结构表征，并采用EPR技术对化合物的抗超氧阴离子自由基性能进行了探讨。     

微晶萘负载PMBP微柱分离预富集与电热蒸发-电感耦合等离子体原子发射光谱联用测定痕量稀土元素

报道了微晶萘负载1-苯基-3-甲基-4-苯甲酰基-5-吡唑酮(PMBP)微型柱分离预富集与电热蒸发-电感耦合等离子体原子发射光谱(ETV-ICP-AES)联用测定痕量稀土元素(Sc,Y,La和Yb)的新方法.试验了影响分离/预富集待测物的各种因素(包括溶液酸度、流速、试样体积、微柱尺寸);研究了吸附有待测物的微晶萘的溶解方法及共存元素对分离/测定的影响.在优化的实验条件下,方法的相对检出限为14pg/mL(Sc),32pg/mL(Y),190pg/mL(La)和26pg/mL(Yb),相对标准偏差(RSD)分别为3.1%,3.5%,4.8%和3.4%(n=9,c=10ng/mL).本法已成功地应用于生物样品中痕量稀土元素(Sc,Y,La和Yb)的测定,结果满意.     

测定粮食、水果、蔬菜稀土总量的

以一定比例的镧、铈、镨、钕、钐的氧化物配制的混合标准溶液在酸性条件下与二溴羧基偶氮胂反应,632nm处的吸光光度在0－1．5mg/L范围内符合比耳珲律,检出限为1．5μg/L,相关系数为0．9995。方法不需加掩蔽剂。试样实测结果的相对标准偏差＜7％（n＝5）,加标回收率在84％－108％之间。     

Fluorescence properties of novel rare earth complexes using carboxyl-containing polyaryletherketones as macromolecular ligands

The fluorescence properties of a series of rare earth (Re³⁺ = Eu³⁺, Tb³⁺) polymeric complexes (PEK-Re³⁺-HLs) using three high-T_g novel carboxyl-containing polyaryletherketones (PEK) as macromolecular ligands and small molecules (HL) such as 1,10-phenanthroline (Phen), dibenzoylmethane (DBM) and 8-hydroxyquinoline (HQ) as co-ligands were investigated by means of fluorescence excitation and emission spectroscopy as well as fluorescence lifetime measurement methods. Among them, PEK-1-Re³⁺-Phens, in which the Re³⁺ ions were coordinated simultaneously with Phen and PEK-1 containing both carboxyl and bulky isopropyl groups on the polymer backbone, exhibited strong fluorescence intensities, long lifetimes, and good film-formation properties. The smooth films of PEK-1-Eu³⁺-Phen and PEK-1-Tb³⁺-Phen, cast from their DMF solutions, could emit bright red and green light under the UV lamp of 365 nm, respectively, which characteristics are of great significance for their potential applications in the large area display material fields. The excellent fluorescence properties of complexes in this study were attributed to the synergistic effects of PEK-1 ligand and Phen co-ligand. Especially, the rigid twisted structure and the bulky isopropyl substituents on PEK-1 backbone forced the coordinated rare earth ion moieties apart, and thus the probability of non-radiative decay rate of Re³⁺ ions at the excited levels were decreased to a large extent.     

High temperature NMR approach of mixtures of rare earth and alkali fluorides: An insight into the local structure

In situ high temperature nuclear magnetic resonance in molten fluoride mixtures gives some structural picture of the complexes existing in the melt, i.e. of their nature and relative proportion. Thanks to the development of a laser heating system associated with a close crucible in boron nitride, we can describe experimentally the evolution of these complexes from the anions and the cations point of view. By ¹⁹F NMR, we have shown the existence of three kinds of fluorine atoms depending on the composition: free fluorine like in pure LiF (non-bonded), bridging fluorine in melts rich in LnF₃ in addition with terminal fluorine singly bonded to one rare earth. Data obtained by NMR spectroscopy are also combined with EXAFS measurements, again thanks to a specific development of the sample holder adapted with molten fluorides and high temperature. This study is a part of our systematic investigation of the different Alk-LnF₃ systems by NMR and EXAFS spectroscopy.     

ICP—AES法中稀土元素间的相互干扰研究

稀土元素的谱线较复杂,相互间存在着不同程度的干扰。本文着重研究了ＩＣＰ－ＡＥＳ法中,它们间的干扰情况,并用几种校正方法进行了比较。