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.

Synthesis, characterization and catalytic activity for H2O2 decomposition of tetrabasic tungstovanadophosphate heteropoly rare earth element complexes with Dawson structure

Nine tetrabasic tungstovanadophosphate heteropoly rare earth element complexes with Dawson structure were synthesized. Their general molecular formulas are K15H4[Ln . (P2W16VO61)(2)] . xH(2)O(Ln = La3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, Yb3+). Their structures and properties were investigated by IR, UV, NMR, ESR, XRD, TG-DTA. The results showed that the series of complexes have the same structure as K-16[Ce(P2W17O61)(2)] . 50H(2)O. At the same time, the catalytic activity of the complexes for H2O2-decomposition was also investigated.

Influence of intraperitoneal injection of rare earth compounds on the activities of antioxidant enzymes and the level of lipid peroxidation in mice livers

Following intraperitoneal injection of lanthanum and terbium chloride and their complexes of diethyltriaminopentagacetic acid (DTPA) to adult mice with a dose of 0.28 mmol/kg body weight/day for three days. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the content of lipid end product, malonaldehyde (MDA) in the mice livers have been assayed respectively. The results show that the activity of SOD was increased and the content of MDA was reduced for LaCl3 treated mice and the two targets were not changed for TbCl3, but the activity of GSH-Px was reduced markedly for both LaCl3 and TbCl3 while the above three targets were not changed for La-DTPA and Tb-DTPA complexes.

The direct electrochemistry of cytochrome c at the nanometer-sized rare earth element oxide particle-modified gold electrodes

The direct electrochemistry of cytochrome c was studied at nanometer-sized rare earth element dioxide particle-modified gold electrodes. It was demonstrated that rare earth element oxides can accelerate the electrochemical reaction of cytochrome c and the reversibility of the electrochemical reaction of cytochrome c was related to the size of rare earth element oxide particles.

W-183 NMR characterization of rare earth heteropolymetalates in aqueous solution

W-183 NMR spectra were obtained for [La(AsW11O39)(2)](11-), [La(As2W17O61)(2)](17-), [La(SiW9Mo2O39)(2)](13-), [LaSb9W21O86](16-), [LaAs4W40O140](25-) and alpha-, beta-[(CeO)(3) . (SiW9O34)(2)](14-) complexes, Tungsten NMR studies showed that the C-s symmetry of the square antiprism for [La(ASW(11)O(39))(2)](11-) and [La(As2W17O61)(2)](17-) anions keep constant in aqueous solution; the lanthanide accupied the central S-1 site in [LnSb(9)W(21)O(86)](16-) and [LnAs(4)W(40)O(140)](25-) complexes, respectively, and lanthanide metal cations gave [(CeO)(3) . (SiW9O34)(3)](14-) type of complexes with SiW9O3410-.

Crystal structure dependence of the luminescence of rare earth ions (Ce3+, Tb3+, Sm3+) in Y2SiO5

The luminescence properties of Ce3+, Tb3+, Sm3+ and energy transfer from Ce3+ to Tb3+ were studied in two modifications of Y2SiO5 (low temperature X(1) type and high temperature X(2) type). The Ce3+ cation shows lower emission energy and larger Stokes shift in X(1)-Y2SiO5 than in X(2)-Y2SiO5, and the emission intensities of Ce3+, Tb3+, Sm3+ in the former are weaker than those in the latter. There exists an energy transfer from Ce3+ to Tb3+ in both types of Y2SiO5, and the transfer efficiency in X(2) type is higher than that in X(1) type. All of these results are discussed in relation to the crystal structure of Y2SiO5.

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.

Preparation and characterization of polymer-supported rare earth complexes

The polymers containing different ligand groups of atoms (mainly O, N, and S) and their rare earth complexes were prepared, characterized and classified based on the type of metal-ligand tending. The catalytic activities of the complexes are briefly discussed. The polymer-supported rare earth complexes showed much greater activities than the corresponding complexes with a low molecular weight.

H-1 and C-13 NMR studies of TTHA complexes with diamagnetic rare earth ions

TTHA complexes with diamagnetic rare earth ions (La3+, Y3+ and LU(3+)) were studied by H-1 and C-13 NMR spectroscopy. A symmetric structural model was suggested for La(TTHA) complex and an asymmetric model for Y(TTHA) and Lu(TTHA) complexes. The complex formation was dependent on the pH value of the solution. The interactions of La(TTHA) with the additional metal ions (La3+, Y3+ and Ca2+) were relatively weak, but relatively strong for that of Lu(TTHA) with the additional Lu3+.

The effect of some factors on the electric properties of rare earth complex oxide

The rare earth complex oxides with different types have been synthesized. Their structures and electric properties have been investigated. According to our experimental results, the effects of the outest shell electronic configuration, electron spin state, electron transport path and formation of cluster on the electric properties of rare earth complex oxides have been summarized. When the electrons in the outest shell of the central metallic ion are unpair, and the outest shell is not half-filled, the electric conductibilities of these compounds are better, If there is a -M-X-M-X- or -M-M-M- (the distances between two atoms <0.31 nm) continuous electron transport path, and the electron configurations of the central metallic ion conform to the above condition, then the electric conductibilities are good, The isolate cluster can not become the continuous electron transport path, therefore, the formation of the isolate cluster will reduce the conductibility.

LUMINESCENCE AND ENERGY-TRANSFER OF RARE-EARTH-METAL IONS IN MG2Y8(SIO4)(6)O-2

The photoluminescence of Ce3+, Tb3+ and Sm3+, and energy transfer from Ce3+ to Tb3+, Dy3+ and Sm3+ in Mg2Y8(SiOd(4))(6)O-2 are reported and discussed. The Ce3+ ion shows blue luminescence under UV excitation, and occupies simultaneously the 4f site and 6h site in the host lattice. The optimum concentrations for the D-5(3) and D-5(4) emissions of Tb3+ and the (4)G(5/2) emission of Sm3+ are determined to be 0.04, 0.20 and 0.10 mol in every mol of Mg2Y8(SiO4)(6)O-2, respectively. The critical distances responsible for the cross-relaxation between the D-5(3)-D-5(4) and F-7(6)-F-7(0) transitions of Tb3+ and between the (4)G(5/2)-F-4(9/2) and H-6(5/2)-F-4(9/2) transitions of Sm3+ are estimated to be 1.43 and 1.06 nm, respectively. Both Tb3+ and Dy3+ can be sensitized by Ce3+, but Ce3+ and Sm3+ quench each other.

INTERACTIONS OF RARE-EARTH LENS WITH BOVINE BLOOD CU(ZN)-SUPEROXIDE DISMUTASE

The interactions of lanthanium trichloride and terbium trichloride with bovine blood Cu (Zn)-superoxide dismutase [Cu(Zn)-SOD] in the aqueous solution of hexamethylenetetrarnine buffer (pH = 6.3) have been studied by using fluorescece, CD and ESR spectra. The results indicated that rare earth ions were coordinated to the carboxyl groups of acidic amino acid residues which were far from active center of the Cu(Zn)-SOD molecule and only lightly disturbed the secondary structure of the enzyme protien, and made the coordination structure of enzyme-bound CU2+ come from the rhombchedron to the axial shape at 77 K and the activity of Cu(Zn)-SOD enzyme was not nearly changed at room temperature.

CHEMICAL-BONDS AND DIELECTRIC-CONSTANTS OF REM (RE=RARE EARTH, M=N, P, AS, SB) CRYSTALS

By using Pillips and van Vechten theory, the chemical bond parameters and dielectric constants of REM (RE=rare earth, M=N, P, As, Sb) crystals were calculated. The values calculated of dielectric constants agree with the experimental values.