Silane bridged polymerized metallocene catalyst for ethylene polymerization

The polymerized metallocene catalyst 4 was prepared by the co-polymerization of ansa-zirconocene complex [CH3Si(2)]ZrCl2 (3) containing vinyl substituted silane bridge with styrene in the presence of radical initiator. Catalyst 4 was found to display high ethylene polymerization activity of 2.28 x 10(6) g PE/(mol . h) with a viscosity average molecular weight (M-eta) value of 61.6 x 10(3) using methylalumoxane (MAO) as a co-catalyst. The ethylene polymerization has been investigated under different conditions.

Polymerized unsymmetrical iron post-metallocene catalyst for ethylene polymerization

The unsymmetrical allyl containing post-metallocene complex [ArN = C( Me)] [(ArN)-N-' = C(Me)]C5H3NFeCl2 [Ar = 2,6(i- Pr)(2)C6H3, Ar' = 4-allyl-2,6-(i-Pr)(2)C6H3] (3) has been prepared and characterized. Complex (3) can be co-polymerized with styrene in the presence of radical initiator to produce polymerized post-metallocene catalyst which exhibits high activity for ethylene polymerization (2.5 x 10(6) g PE/mol Fe.h).

Matrix effects in flow injection-inductively coupled plasma mass spectrometry

Matrix effects in now injection (FI) inductively coupled plasma mass spectrometry has been studied,and the results have been compared with those of continuous nebulization. The matrix element As and nu with higher ionization potential ( > 9eV) have enhancement effect on the analyte signal,and the heavier the analyte mass, the smaller the enhancement effects by Fl. The matrix elements Cu, In, Li, Na and Pb with lower ionization potential have suppression effect on the analyte signal. The heavier the matrix element mass, the more severe the suppression effects. The heavier the analyte mass, the smaller the suppression effects. The higher ionization potential of analyte, the more severe the suppression effects. Compared with continuous nebulization, the degree of suppression effect is smaller and the degree of the enhancement effect is larger by Fl.

Phosphors for plasma display panels

Excitation and emission characteristics were reviewed for phosphors which were reported, applied, or suggested for the plasma display panel (PDP). Correlation of luminescence characteristics to the host crystal structure and the activator of the phosphor was explained. Improvements of the PDP phosphor for practicality were considered. (C) 2000 Elsevier Science S.A. All rights reserved.

Matrix effects in inductively coupled plasma mass spectrometry by use of organic solvents

Matrix effects arising from ethanol, propanol, glycerol, acetic acid, ethylenediamine and triethanolamine in inductively coupled plasma mass spectrometry have been studied. Addition of ethanol, propanol, glycerol, acetic acid, ethylenediamine and triethanolamine into solution has an enhancement effect on the signal intensity of analyte with ionization potential between 9 and 11 eV. The ethylenediamine and triethanolamine have higher enhancement effect on the signal intensity of Hg than that of ethanol, propanol, glycerol and acetic acid. Addition of ethylenediamine and triethanolamine into solution has a suppression effect on the signal intensity of Ph and Sr. The mechanism of the enhancement or suppression was investigated. The signal enhancement of Hg in the presence of ethylenediamine and triethanolamine is not caused by improved degree of ionization of Hg and nebulization efficiency. The suppression effects of Ph and Sr in the presence of ethylenediamine and triethanolamine are due to decrease of atomization efficiency of these elements. A method for the determination of Hg in the biological standard samples Ly ICP-MS was developed.

Poly(3-dodecylthiophenes) polymerized with different amounts of catalyst

The effect of the amount of the catalyst FeCl3, used during the direct oxidation polymerization, on the structure and properties of the obtained poly(3-dodecylthiophene) (P3DDT) was investigated in this paper. Such measurements as gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) spectroscopy, thermal analysis, X-ray diffraction, infrared spectroscopy (FTIR) and ultraviolet-visible (W-vis) spectroscopy were applied. It is found that a suitable addition of FeCl3 can contribute to generate a P3DDT with greater percentage of head-to-tail head-to-tail (HT-HT) linkages, which are generally favored. The reduction of the other linkage defects helps to lengthen conjugation length, thus leading to more orderly chain packing. (C) 2000 Elsevier Science S.A. All rights reserved.

Determination of ultra-trace rare-earth elements in human plasma by inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS),a highly sensitive inorgnic analytic technique,fits to determine ultra-nace rare-earth elements in human plasma. Under the optimized conditions detection limits for 15 rare-earth elements are in the range of 0.7 (for Eu)-5.4 (for Gd) ng.L-1. Indium as an internal standard element is used to compensate for matrix suppression effect and sensitivity drift. Three kinds of preparation methods, diluted with 1% HNO3, digested with HNO3-H2O2 and with HNO3-HClO4, are checked and compared,and the former is the simplest way to be measured. The samples diluted with 1% HNO3, stored in 4 degrees C, are very steady for 16 days. With the method, 11 healthy plasma samples in Changchun area of China are analysed.

Study on speciation of Pr(III) in human blood plasma by computer simulation

Speciation of Pr(III) in human blood plasma has been investigated by computer simulation. The speciation and distribution of Pr(III) has been obtained. It has been found that most of Pr(III) is bound to phosphate and to form precipitate. The results obtained-are in accord with experimental observations.

Gas-phase ion-molecule reactions of C-60 with the plasma of methyl acrylate

The gas-phase ion-molecule reactions of C-60 with the plasma generated from methyl acrylate under self-chemical ionization conditions were studied by use of a triple-quadrupole mass spectrometer. The adduct cation [C60C3H3O](+) and protonated molecular ion [C60H](+) were observed as the major product ions. The former adduct ion is formed by electrophilic reaction of C-60 with the ion [CH2=CHCO](+), a main fragment ion resulting from the methyl acrylate molecular ion [CH2=CHCOOCH3](+) through alpha cleavage. The latter ion is generated by proton transfer from protonated methyl acrylate to C-60. Semi-empirical quantum chemical calculations have been performed for the eight possible isomers of [C60C3H3O](+) at the Hartree-Fock level by use of the AMI method. The results show three types of cycloadducts as the most stable structures among the possible isomers.

Studies on insoluble species of Gd (III) in human blood plasma by computer simulation

The insoluble species of Gd (III) in human blood plasma were investigated by computer simulation. The distribution of the Gd (I) species was obtained. It was found that most of the Gd (III) ions were bound to phosphate to form precipitate GdPO4 at the concentration of 1. 000 x 10(-7) mol/L and when the concentration of the Gd (III) increased to 3. 750 x 10(-4) mol/L, in excess of the concentration of phosphate, the Gd (III) ions were bound to carbonate to form another kind of precipitate, Gd-2 (CO3)(3).

Tb(III) speciation in human blood plasma by computer simulation

A multi-phase model was developed and Tb(III) speciation in human blood plasma was studied. At a concentration below 3.744x 10(-4) mol/L (or at the concentration), Tb(III) is mostly bound to phosphate to form precipitate of TbPO4. As the concentration of Tb(III) increases, phosphate is exceeded and another kind of precipitate of Tb-2(CO3)(3) appears. Among soluble Tb(III) species, Tb(III) mainly distribute in [Tb (Tf)] at low concentration and in [Tb (HSAA, [Tb-2 (Tf)], [Th (IgG)], [Tb (Lactate)](2+), [Tb (CitArgH)] and free Tb(III) at high concentration.

Application of inductively coupled plasma mass spectrometry in biological samples analysis

Recent important applications of inductively coupled plasma mass spectrometry in biological samples analysis are reviewed. The sample preparation, sample introduction techniques, interference correction and typical applications are introduced in detail with 154 references.

Characteristics in frequency domain by inductively coupled plasma atomic emission spectrometry with charge injection detection

The charactesistics of two-dimension spectra obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) with charge injection detection (CID) in frequency domain were studied in the present paper. The measurement spectra were Fourier transformed and the frequency distribution of the spectra was obtained. Results showed that the spectra in frequency domain could he divided into two parts:high frequency and low frequency signals. The later stood for measurement spectra and the former for background and noises. However, the high frequecny signals could not be smoothed simply to reduce noises because the background was deteriorated even though the spectral signal did not change significantly.

Study on effect of Gd (III) speciation on Ca (II) speciation in human blood plasma by computer simulation

Ca (II) speciation and effect of Gd (III) speciation on Ca (II) speciation in human blood plasma were studied by computer simulation. [CaHCO3](-) is a predominant compound species of Ca (II). Gd (III) can compete with Ca (II) for biological molecules. The presence of Gd (III) results in a increase of concentration of free Ca (II) and a decrease of concentration of Ca (II) compounds.

Determination of the impurities elements in high-purity cadmium by inductively coupled plasma mass spectrometry

A method for the determination of impurity elements in high purity cadmium by inductively coupled plasma mass spectrometry was developed. The spectral interference arising from Cd was discussed and the magnitude of interference by the polyatomic ion of Cd was compared. The effect of the high concentration Cd on the analyte signal was studied. The results showed that Cd possessed both significant suppression effects on the light mass elements signal and enhancement effects on the heavy mass elements signal,and the effects can be corrected by the use of internal standard elements. In this paper, Y and Bi was employed for the light mass elements and the heavy mass elements,respectively. As, Be, Co, Cu, Ga, Ge, Mn, Mo, Pb, Ni, Sr, Au, Tl, Th, V and U in high purity cadmium were determined. Detection limits are 0.005-0.052 mu g L-1,and the recoveries of standard addition are 82%-108%.