Luminescent Langmuir-Blodgett films based on Tiron-terbium

The luminescent ultrathin Langmuir-Blodgett (LB) films containing Tb-2(C6H3S2O8)(2) (Tiron-Tb) were successfully obtained. The modifications of compression isotherms of dimethyldioctadecylammonium bromide (DODA) have been observed when the Tiron-Tb complex was dissolved in the subphase. The effect of Tiron-Tb in the subphase on Langmuir films of DODA has been studied. Low-angle X-ray diffraction result indicates that the LB films have a good periodic layered structure. The UV and IR spectra results show the Tiron-Tb complex is incorporated into LB films layer-by-layer and the LB films are homogeneously deposited. The LB films containing Tiron-Tb can emit strong green luminescence, and the luminescence signal can be detected from a single layer. The luminescence properties of LB films have been discussed compared with those of the solutions.

Multiple melting and crystallization behavior of nylon 1212

The wide-angle X-ray diffraction (WAXD) patterns of isothermally crystallized Nylon 1212 show that gamma-form crystals form below 90 degrees C and the alpha-form crystals call exist above 140 degrees C. In the temperature range of 90-140 degrees C, the a-form gamma-form crystals coexist. Variable-temperature WAXD exhibits that the nylon 1212 gamma-form does not show crystal and transition on heating, while a-form isothermally crystallized at 160 degrees C exhibits Brill transition at a little higher than 180 degrees C on heating. The multiple melting behaviors of Nylon 1212 isothermally crystallized from melt come from a complex mechanism of different crystal structures, dual lamellar population and melting-recrystallization. In polarized optical microscope (POM) observations, Nylon 1212 isothermally crystallized at 175 degrees C shows the ringed banded spherulites. However, at temperatures below 160 degrees C the ringed handed image disappears, and cross-extinct spherulites are formed.

Comparison between GdDTPA and two gadolinium polyoxometalates as potential MRI contrast agents

Two gadolinium polyoxometalates, Gd2P2W18O62 and K-15[(GdO)(3)(PW9O34)(2)], have been evaluated by in vivo as well as in vitro experiments as the candidates of tissue-specific magnetic resonance imaging (MRI) contrast agents. T-1-relaxivities of 28.4 mM(-1)-s(-1) for Gd2P2W18O62 and 11.2 mM(-1)-s(-1) for K-15[(GdO)(3)(PW9O34)(2)] (400 MHz, 25 degreesC) were higher than that of the commercial MRI contrast agent (GdDTPA). Their relaxivities in bovine serum albumin and human serum transferrin were also reported. The favorable liver-specific contrast enhancement and renal excretion capability in in vivo MRI with Sprague-Dawley rats after i.v. administration of K-15[(GdO)(3)(PW9O34)(2)] was demonstrated. In vivo and in vitro assay showed that K-15[(GdO)(3)(PW9O34)(2)] is a promising liver-specific MRI contrast agent. However, Gd2P2W18O62 did not show the favorable quality in vivo as expected from its high relaxivity in vitro, which was attributed to low bioavailability, indicating that it is of limited value as tissue-specific MRI contrast agent.

Solvothermal synthesis of the complex fluorides KMgF3 and KZnF3 with the Perovskite structures

The complex fluorides KMgF3 and KZnF3 with Perovskite structures were solvothermally synthesised at 150-180degreesC and characterised by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis and infrared spectroscopy.

Relationship between chemical bond parameters and superconducting temperature in HgBa2Can-1CunO2n+2+delta (n=1, 2, 3, 4)

Bond covalency and valence of elements in HgBa2Can-1CunO2n+2+delta (n = 1, 2, 3, 4) were calculated and their relationship with T-c was discussed. For both oxygen and argon annealed samples, the results indicated that with the increase of n, the trend of bond covalency of Hg-O and Cu-O was the same or opposite compared with that of superconducting temperature. This may suggest that the magnitudes of Cu-O and Hg-O bond covalency are important in governing the superconducting temperature. For the highest T-c sample, Hg had the lowest valence, implying that lower valence of Hg was preferred in order to produce higher T-c. For fixed n, the valence of Cu in oxygen annealed samples was larger than that in argon annealed samples, indicating that oxygen annealed samples produced more carriers than argon annealed samples.

稀土对肝脏作用的机制

综述了稀土对肝脏作用的机制 ,稀土不仅能引起肝脏形态学的改变 ,当稀土进入肝细胞后可与多种蛋白质等分子发生相互作用 ,并影响多种酶的活性 ,还能通过信使分子干扰肝脏正常的生理功能。

电喷雾串联质谱法鉴定桔梗皂苷D

改进了桔梗皂苷D的提取、分离及鉴定方法 .首次利用大孔树脂脱糖脱色及薄层硅胶作色谱系介质 ,并首次利用电喷雾质谱对目标化合物进行跟踪分析 ,使高纯度的目标化合物的分离和鉴定工作得以简化

Electrospray ionization multiple-stage tandem mass spectrometric analysis of diglycosyldiacylglycerol glycolipids from the bacteria Bacillus pumilus

Electrospray ionization (ESI) combined with multiple-stage tandem mass spectrometry (MSn) was used to directly analyze the glycolipid mixture from bacteria Bacillus pumilus without preliminary separation. Full scan ESI-MS revealed the composition of picomole quantities of glycerolglycolipid species containing C-14-C-19 fatty acids, some of which were monounsaturated, Two main components were identified from their molecular masses and fragmentation pathways. The fragmentation pathway of the known compound compared with the investigated compound verified the proposed structure as 1(3)-acyl-2-pentadecanoyl-3(1)-O-[beta-D-glucopyranosyl-(1-->6)-O-beta-D-glucopyranosyl]-sn-glycerols. A comparison of the multiple tandem mass spectra of the different alkali-metal cation adducts indicates that the intensity of fragments and the dissociation pathways are dependent on the alkali-metal type, The basic structures of glycerolglycolipids were reflected clearly from the fragmentation patterns of the sodium cations, The intense fragments of the sugar residue from the precursor ions were obtained from the lithiated adduct ions. ESI-MSn spectra of [M + K](+) ions did not provide as much fragmentation as [M + Na](+) and [M + Li](+) adducts, but their spectra allow the position of glycerol acylation to be determined. On the basis of MS2 spectra of[M + K](+) ions, it was established that all components have a C-15:0 fatty acid at the sn-2 position of the glycerol backbone and C-14-C-19 acids at the sn-1 position of the glycerol backbone. Copyright (C) 1999 John Wiley & Sons, Ltd.

Ca_5(PO_4)_3Cl中铕和铽间的电子转移

本文通过对铕和铽在Ｃａ５（ＰＯ４）３Ｃｌ基质中的发光特征的研究，发现铕和铽之间存在着电子转移现象，并对其反应机理进行了探讨。Ｅｕ３＋（４ｆ６）和Ｔｂ３＋（４ｆ８）通过电子转移使它们达到电子结构稳定的Ｅｕ２＋（４ｆ７）和Ｔｂ４＋（４ｆ７）。在同一基质中双掺铕和铽时，在２５４ｎｍ紫外光激发下，能同时观察到Ｅｕ２＋，Ｅｕ３＋和Ｔｂ３＋的发射，这一现象的发现为单基双掺希土三基色荧光粉的研制提供了理论依据。

中空纤维膜萃取分离混合稀土中的钍

通过中空纤维膜逆流萃取，研究了伯胺Ｎ１９２３对Ｔｈ４＋和ＲＥ３＋的萃取分离过程。测定了水相料液硫酸浓度、水相与油相流量对传质系数的影响，并对包头矿硫酸分解浸出液进行中空纤维膜萃取实验。结果表明，Ｔｈ４＋的传质系数受水相流量影响，与酸度及油相流量无关，总传质速率受水相临界层传质步骤控制。ＲＥ３＋的传质系数不受水相流量影响，油相流量影响很小，但受硫酸浓度的影响，总传质速率受萃取反应速率控制。根据传质速率的不同，对包头矿硫酸浸出液进行萃取分离，在８ｈ内Ｔｈ４＋可基本萃取完全，而ＲＥ３＋及Ｆｅ３＋基本不被萃取，故可在密封条件下分离钍。

新型稀土功能材料

本文对稀土光、电、磁等功能材料的发展作了评述，并就我国开展稀土功能材料及有关基础问题的研究提出了建议.

KCl-LiCl共晶熔体中Nd~(3+)和Ho~(3+)的电化学行为

用循环伏安法和恒电流电解后的电位时间曲线法，研究了ＬｉＣｌＫＣｌ熔体中Ｎｄ３＋和Ｈｏ３＋在Ｍｏ电极上的电化学行为。结果表明，Ｎｄ３＋和Ｈｏ３＋在Ｍｏ电极上的还原都为一步３电子可逆过程。其扩散系数分别为：１１３×１０－６和２１４２×１０－５ｃｍ２·ｓ－１（４５０℃），４５０℃下Ｈｏ３＋／Ｈｏ电极对的标准氧化还原电位为２９８７Ｖ（ｖｓ·Ｃｌ／Ｃｌ－１），并讨论了实验值较理论值偏负的原因。

Cryoimmobilized enzyme for biosensor construction

A new immobilization material and an immobilization method for a glucose sensor with HEFc (hydroxyethylferrocene) as mediator is described. In the course of three months, the enzyme electrode shows almost no deterioration in its response characteristics. The response time is less than 30 s. The electrode has a wide linear range up to 10 mmol l(-1) with good repeatability. The kinetic parameters have also been calculated.

A comparison of electrocatalytic ability of various mediators adsorbed onto paraffin impregnated graphite electrodes for oxidation of reduced nicotinamide coenzymes

Twelve mediators have been modified by adsorption onto the paraffin impregnated graphite electrodes (IGE). The resulting electrodes exhibit electrocatalytic activity of different degrees towards oxidation of 1,4-dihydronicotinamide adenine dinucleotide (NADH). The electrocatalytic ability of the chemically modified electrode (CME) depends mainly on the formal potential and molecular structure of mediator. The formation of the charge transfer complex between NADH and adsorbed mediator has been demonstrated by the experiments using a rotating disk electrode. An electrocatalytic scheme obeying Michaelis-Menten kinetics has been confirmed, and some kinetic parameters were estimated. The solution pH influences markedly the electrocatalytic activity of the modified electrode. Various possible reasons are discussed.

Study on the modified electrode of conducting polymers .3. Electron spin resonance characteristic of polypyrrole film electrode doped with heteropolyanions

The ESR of PPy films doped with Co (W2O7)(6)(10-) and CuW12O406- ions were reported and discussed. Results show that heteropolyanions not only play the role of neutralizing electricity in the PPy film, but also interact with the PPy molecular chain to form some adducts. The adducts affect the electronic structure of the PPy film and are unstable at more positive or more negative potentials. Dysonian ESR lineshape was recorded for the dry PPy film with CuW12O406- for the first time.