稀土富勒烯提取液的激光解吸飞行时间质谱研究

采用激光解吸飞行时间质谱对含镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钐(Sm)、铕(Eu)、钆(Gd).铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)等13种稀土富勒烯的提取液进行了研究.考察了正负谱、激光强度、底物以及质量歧视对分析结果的影响,并由此确定了最佳分析条件.结果表明,提取液中除了空心富勒烯外,还存在较多量的稀土富勒烯.通过对它们谱峰相对强度之间的比较,探讨了不同稀土元素嵌入富勒烯球笼的结构稳定性及溶解性能的差别以及产生这种差别的可能原因.

锗-132的稀土配合物对5'-腺嘌呤及5’-脱氧腺嘌呤核苷酸的水解断裂作用

核酸是重要的生命物质,对核酸序列的选择性切割是当前基因工程的关键问题.在生理条件及非酶存在下,核酸非常稳定(磷酸二酯键在pH 7,25℃时的半衰期为2亿年,因此,近年来研究的人工酶是通过氧化脱氧核糖来切断DNA的,而有关选择性水解断裂核酸的报道则很少,主要困难是缺乏高效的“分子剪刀”,有关稀土对核酸断裂的研究报道尚不多见.作者曾报道了除Ce(Ⅳ)外,其他稀土对5’-腺嘌呤核苷酸(5’-AMP)及5’-鸟嘌呤核苷酸(5’-GMP)均无明显水解作用,并且过去报道的体系为碱性介质,此时稀土以氢氧化物沉淀形式存在为非均相体系,其应用局限性非常大,因此,寻求可溶性的稀土水解核酸体系就显得非常重要.本文用核磁共振(NMR)和化学法研究了Yb-Ge-132和Pr-Ge-132配合物对5’-AMP及5’-dAMP的断裂作用,指出Yb-Ge-132和Pr-Ge-132使5’-AMP水解为腺苷(A)及无机磷,使5’-dAMP水解为脱氧腺苷(dA)及无机磷,其断裂机制为水解断裂,这对于研究稀土与核酸的作用,寻找新的核酸均相水解体系都具有非常重要的意义.

Rheological properties and crystallization behavior of yttrium oxide filled low ethylene content polypropylene copolymer

The rheological properties and crystallization characteristics of low ethylene content poly propylene (EPM) with and without Yittrium oxide (Y2O3) as a filler was investigated by cone-plate viscometer and differential scanning calorimetry. Yittrium oxide had a profound effect on the viscosities of the systems. To determine the nonisothermal crystallization rate of the materials, a new estimation method was used. From the results, we can conclude that Y2O3 acts as a nucleating agent, which increased the crystallization rate of the EPM. (C) 1996 John Wiley & Sons, Inc.

Crystal structure and its transition for poly(aryl ether ketone ketone)s .1.

Poly(aryl ether ketone ketone)s (PEKK) was a high-performance engineering plastics, By means of Wide Angle X-ray Diffraction (WAXD) and Differential Scanning Calorimetry (DSC) methods, PEKK samples crystallized in solvent induction, from glass state and from melting state were studied, Crystal forms I and II for PEKK were found, The formation of crystal form II was dependent on thermal history and solvent induction, and this form II had melting point 10 degrees C or so lower than that of form I crystallized from glass state, All PEKK samples had low melting peaks which were relevant to the polarization of PEKK molecular chain, while they had nothing to do with thermal history, The heat of fusion for PEKK low melting peaks accounted for,percentage of 2 to 10 or so of the whole heat of fusion, And PEKK has its equilibrium melting point of 409 degrees C.

Synthesis and thermo-decomposition mechanism of rare earth complexes with phenylacetic acid

Rare earth complexes with phenylacetic acid (LnL(3) . nH(2)O, Ln is Ce, Nd, Pr, Ho, Er, Yb and Y, L is phenylacetate, n = 1-2) were prepared and characterized by elemental analysis, IR spectroscopy, chemical analysis, and X-ray crystal structure. The mechanism of thermal decomposition of the complexes was studied by means of TG-DTG, DTA and DSC. The activation energy and enthalpy change for the dehydration and melting processes were determined.

Crystal structure of polypropylene filled with rare earth oxides

The effect of a fine powder of Y2O3, Nd2O3, and Ho2O3 on the crystal structure of isotactic polypropylene (iPP) was studied with WAXD and DSC techniques. The results showed that the addition of the three rare earth oxides (REOs) can increase the crystallite size of the alpha-form crystal and the degree of crystallinity of iPP at an annealing temperature of 120 degrees C and that both Y2O3 and Nd2O3 are the beta-nucleator of iPP. REOs enhance the overall growth rate of the spherulites of iPP. All the iPP samples filled with REOs which were crystallized isothermally at 132 degrees C from the melt exhibited their melting peaks of the beta-form on the DSC heating traces, indicating that the REOs are the nucleating agents for both the alpha- and beta-forms of iPP under isothermal conditions. (C) 1996 John Wiley & Sons, Inc.

Copolymerization of styrene with butadiene and isoprene using a rare earth catalyst

In the copolymerization of styrene-butadiene and styrene-isoprene, a novel rare earth catalyst system (CF3CO2)(3)Ln/R(3-n)AlH(n)/(CH3)(3)CCH2Br (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; R = Me-, Et-, i-Bu-, and Oct-; n = 0 and 1) has been studied. The 1, 4 unit contents in the copolymers obtained are found to range from 64.4 to 99.6% with St contents of 5.2 to 59.9%, and intrinsic viscosities of 0.1 to 0.5 dl g(-1) measured by i.r., H-1 n.m.r. and C-13 n.m.r. spectra. From the calculated data of linked ratios, a change in the microstructure is induced by the styrene unit, probably adjacent to the butadiene or isoprene unit. An interesting result is that the ratios of styrene unit linked with 1, 2 or 3,4 units in the copolymers are far higher than in copolymers obtained with the nickel catalyst. The experimental results are discussed in terms of rare earth pi-allyl coordination and back-biting mechanism.

二烷基单硫代膦酸萃淋树脂吸附重稀土(Ⅲ)的研究

本文研究了Cyanex302萃淋树脂从硝酸介质中吸附重稀土（Ⅲ），吸附能力为Lu＞Yb＞Tm＞Er＞Ho＞Dy＞Tb＞Gd。考察了平衡水相酸度、稀土浓度、温度等对吸附平衡的影响。计算了重稀土（Ⅲ）间的平均分离系数β~z+1_z＝3．55，表明分离稀土（Ⅲ）的选择性优于HDEHP、HEH／EHP萃淋树脂，有可能用于制备高纯单一重稀土。Cyanex302萃淋树脂饱和吸附稀土（Ⅲ）的红外光谱表明，P＝S键参与了配位。

一种新的稀土配合物结构分析方法——无顺磁位移混合三稀土法

提出无顺磁位移混合三稀土配合物结构分析方法,并以丙氨酸稀土为例,选取Eu-Yb-Pr和Er-Yb-Pr体系从实验上予以验证.研究发现,通过选择适当的三种顺磁性稀土离子以一定比例混合,可以抵消顺磁诱导位移,仅保留顺磁弛豫增强效应,因而可直观地从谱线半高宽(W_(1/2))看出稀土配合位点,从纵向弛豫时间(T_1)或谱线半高宽计算稀土与配体磁核间的相对距离.

ELECTROCHEMICAL-BEHAVIOR OF BIS(2 /17-ARSENOTUNGSTATE) LANTHANATES AND THEIR ELECTROCATALYTIC REDUCTION FOR NITRITE

A series of new catalysts, K-14[Ln(As2W17O61)(2)]. xH(2)O (Ln = La, Pr, Sm, Eu, Gd, Tb, Dy, Tm and Yb) which can electrocatalyze reduction of nitrite are presented and their electrochemical behavior is described in this paper. Bis(2:17-arsenotungstate) lanthanates which are monovacant Dawson derivatives, exhibit two 2-electron and one 1-electron waves, attributed to electron addition and removal from the tungsten-oxide framework that comprises each anion structure. The formal potentials of redox couples are dependent on solution pH. Double-hump principle of formal potentials takes effect with increasing atomic number of lanthanide elements following their special electronic shell structure. The third waves of all the heteropolyanions have good electrocatalytic activities for nitrite reduction at pH 5.0.

SYNTHESIS OF THE CLINOPYROXENES JOIN CAMGSI2O6-NAALSI2O6 FOR JEWELRY

Clinopyroxenes of the join CaMgSi2O6(diopside)-NaAlSi2O6 (jadeite) were synthesized in the temperature range 800-1900 degrees C and under varying pressure, 10-55 kbar. The stability regions of various compositions of diopside-jadeite have been established experimentally using different compositions of glass materials: stoichiometric composition NaAlSi2O6, 0.1CaMgSi(2)O(6)-0.9NaAlSi(2)O(6), 0.2CaMgSi(2)O(6)0.8NaAlSi(2)O(6), 0.3CaMgSi(2)O(6)-0.7NaAlSi(2)O(6), and 0.4CaMgSi(2)O(6)-0.6NaAlSi(2)O(6). Unit cell parameters of synthetic clinopyroxenes with the above compositions were determined. The physical properties, such as hardness, toughness, density, and refractive index, etc., were also measured. The results show that synthetic clinopyroxenes have the same properties as the natural one. The gem quality of diopside-jadeite clinopyroxenes was achieved by synthesised on the basis of the above experiments. Various colouring agents, such as Cr2O3, Co2O3, NiO2, Fe2O3, TiO2, MnO, CuO, and their combinations, FeO-Cr2O3, etc., were added to obtain the different colours of gem. In addition, small amounts of the rare-earth oxides, such as CeO2, Nd2O3, Sm2O3, Dy2O3, Eu2O3, Er2O3, Pr6O11, Lu2O3 and CuO-Eu2O3, Co2O3Nd2O3, etc., were also added to produce fluorescent clinopyroxenes for jewellery.

2-乙基己基磷酸单(2-乙基己基)酯萃淋树脂分离-火花源质谱法测定高纯氧化镱中痕量稀土杂质

本文采用萃取色谱法以2-乙基已基膦酸单(2-乙基已基)酯(P_507)萃淋树脂为固定相,以HCI-NH_4CI体系为淋洗液,研究了99.999%~99.9999%的高纯Yb_2O_3中稀土杂质和Yb基体的分离条件,将杂质淋洗液富集于复合螯合剂-活性碳上,经灼烧灰化后制成样品电极,进行质谱测定.测定下限达 0.01~0.05 μg/g,可用于高纯 Yb_2O_3中杂质的测定.回收率在80%以上.

MF_2:Eu,Ce(M=Ca,Sr,Ba)中稀土离子的价态变化

我们已经实验证明并报道了Eu-Tb之间、Ce-Yb之间的电荷转移.本文首次实验证实了Ce~(3+)离子和Eu~(3+)离子之间电荷转移现象的存在,进一步阐述了稀土价态与其电子组态共轭特征的相关性.1 实验部分1.1 试剂CaF_2,SrF_2,BaF_2,NH_4HF_2、氢氟酸、盐酸均为分析纯,EuF_3和CeF_3分别由高纯Eu_2O_3(99.95%)及CeO_2(99.99%)自制.1.2 MF_2:Eu,Ce体系的合成按化学计量比(MF_2:X%CeF_2,y%EuF_3;X=1,y=0,0.1,0.3,0.5,1;X=0,0.05,0.1,0.3,0.5,y=1)准确称取原料,放人玛瑙研钵中充分研混后装入刚玉柑涡中,置于管状炉内(用氢气

氯化-甘氨酸六水合稀土固体络合物的合成及红外光谱研究

本文用稀土氯化物与甘氨酸反应制备了标题络合物[Ln(Gly)·6H_2O]·Cl_3(Ln=Nd,Sm,Gd,Er,Yb),测定了络合物的红外光谱,对其主要吸收带进行了归属。红外光谱的研究结果表明,甘氨酸以内盐的形式存在于络合物中,通过羧基与稀土离子配位。水分子也参与了配位。并推测,Nd的络合物为双核络合物,其它稀土络合物具有一维无限长链结构。

谷胱甘肽与稀土离子作用的~(13)C NMR研究

本文利用顺磁稀土离子的诱导化学位移变化的性质,研究了多官能团配体谷胱甘肽(GSH)与稀土的配位作用.在水溶液中GSH通过分子两端的羧基负离子与稀土形成遥爪配位结构.谷氨酸端和甘氨酸端羧基与Eu~(3+)的配位稳定常数分别为12.5±0.1L/mol和100.0±0.5L/mol.从~(13)C化学位移的pH变化曲线求得谷氨酸端和甘氨酸端羧基解离的pK_a值分别为2.20±0.02和3.50±0.04.对Dy~(3+)、Ho~(3+)、Er~(3+)、Tm~(3+)和 Yb~(3+)作用下,GSH的~(13)C位移数据分析表明,配体与这些离子形成同构的配合物,分子两端羧基均可能以双齿形式与稀土配位.