CARBON FILMS PREPARED BY PLASMA POLYMERIZATION OF NATURAL GAS(Ⅰ)DEPOSITION AND CHARACTERIZATION OF CARBON FILMS

Plasma polymerization of natural gas has been investigated in a capacitively coupled RFdischarge apparatus.Carbon film with diamond-like properties was obtained.The structure of the filmwas characterized by IR,XPS,Raman spectroscopy and elemental analysis,etc..     

ASSIGNMENT OF ~(13)C-NMR SPECTRA OF POLYMER WITH SEMIEMPIRICAL METHOD——A STUDY OF VINYL TERTIARY CARBON IN 1,2-POLYBUTADIENE (1,2-PBD)

Matrix multiplication technique has been employed to calculate the probabilities of different rotational isomeric states of the bonds in the main chains of 1, 2-PBD. Using the relation that relative chemical shift is in proportion to the sum of bond probabilities which make contribution to the chemical shift of a certain carbon, a new assignment has been obtained directly from the sum of bond probabilities. According to the assignment, these pentads are mmmm, mmmr, rmmr, mmrr, mmrm, rmrr, rmrm, rrrr, mrrr and mrrm from downfield to upfield.In order to prove experimentally the result mentioned above, isotactic 1,2-PBD was successfully synthesized in our lab. The polymer is identified by the infrared spectroscopy, X-ray diffraction and differential scanning calorimetry. Comparison between the ~(13)C-NMR spectra of heterotactic and isotactic 1,2-PBD reveals that the first peak downfield in the former represents the pentad mmmm. Consequently, the assignment is in agreement with neither that of Elgert nor th     

MORPHOLOGY EVOLUTION IN PTFE AS A FUNCTION OF MELT TIME AND TEMPERATURE——Ⅰ. HIGH MOLECULAR WEIGHT SINGLE- AND MULTI-MOLECULE FOLDED CHAIN SINGLE CRYSTALS AND BAND STRUCTURES

The effect of sintering dispersed dispersion and nano-emulsion particles of high molecular weight polytetrafluoroethylene (PTFE) on a substrate as a function of “melt” time and temperature is described. Folded chain single crystals parallel to the substrate and as ribbons on-edge (with double striations), as well as bands, are produced for longer sintering times; particle merger and diffusion of individual molecules, crystallizing as folded chain, single (or few) molecule,single crystals when “trapped” on the substrate by cooling occur for shorter sintering times. It is suggested the observed structures develop with sintering time, in a mesomorphic melt. The structure of the nascent particles is also discussed.     

CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS——Ⅰ.POLY(P-PHENYLENE TEREPHTHALATE)*

The morphology and crytal structure of poly(p-phenylene terephthalate) (PPT), prepared by confined thin filmmelt (CTFMP) and solution (CTFSP) and bulk solution polymerization, were characterized by transmission electronmicroscopy, electron dimaction and molecular modeling. The unit cell is monoclinic (P2_1/a space group) with parameters a =7.89, b = 5.49, c = 12.65 A, α=γ= 90°, β=100.33°, density = 1.48 g/cm~3, the a, b and β values differing slightly from thosereported previously in the literature. A degree of variation in relative intensities of hk0 reflections in, apparently, untilted[001] ED patterns was observed from a given sample, suggesting some variation in molecular packing. ED evidence wasfound for a second phase, with [001] appearing the same as for phase Ⅱ of the related poly(p-oxybenzoate) (PpOBA)polymer. CTFMP crystals polymerized above 220℃ (up to 370℃) and CTFSP crystals polymerized at 300℃ consisted oflamellae 100-200 A thick.     

MORPHOLOGY EVOLUTION IN PTFE AS A FUNCTION OF MELT TIME AND TEMPERATURE——Ⅱ. LOW MOLECULAR WEIGHT FOLDED CHAIN SINGLE CRYSTALS AND BAND STRUCTURES

The effect of sintering dispersed and bulk, low molecular weight (Mn = 50,000 Da), nano-emulsion polytetrafluoroethylene (PTFE) particles near their melting point is described. With the nascent particles consisting of ca.75 nm diameter, hexagonal, single crystals, sintering at, e.g., 350℃, results, initially, in merger of neighboring particles,followed by individual molecular motion on the substrate and the formation of folded chain, lamellar single crystals and spherulites, and on-edge ribbons. It is suggested these structures develop, with time, in the mesomorphic “melt”. Sintering of the bulk resin yields extended chain, band structures, as well as folded chain lamellae; end-surface to end-surface merger,possibly by end-to-end polymerization, occurs with increasing time.     

MOLECULAR CLONING OF A NEW VARIANT OF HUMAN PAPILLOMAVIRUS TYPE 6 ISOLATED FROM A CHINESE WOMAN AND EXPRESSION OF ITS L1 GENE IN E. coli——MOLECULAR CLONING & EXPRESSION OF HPV6 GENE

A human papillomavirus genome DNA of 7.9 kb from a Chinese woman with genital condyloma acuminata was cloned in Bam HI site of pAT153. According to the results obtained from Southern blotting, restriction mapping as well as partial DNA sequencing, the isolated genome (HPV6BV) had obvious variance and was referred to as a new variant of HPV6 found in China the first time. HPV6BV L1 gene was successfully expressed in E. coli as a fusion protein with pUR288. The β-galactosidase/L1 fusion protein reacted with both β-galactosidase antiserum and HPV antibody using Western blot technique. The E. coli-produced fusion protein, possessing HPV antigenicity, may provide a reagent for clinical diagnosis and epidemiological survey.     

A STUDY ON ~(10)Be IN QUARTZ FROM LOESS OF CHINA (Ⅰ)——In situ COSMOGENIC ~(10)Be AND EROSION RATES OF SOURCE REGIONS OF LOESS

In situ cosmogenic ~(10)Be in quartz from loess deposited in the last 2,000,000 a is considered to have been derived mainly from initial ~(10)Be in source regions and it bears abundant information about changes in erosion rates of source regions. As [have been estimated, the concentrations of "in situ cosmogenic ~(10)Be" in quartz from samples GL47(L1) andGL83 (L2) collected from the Luochuan loess section are 5×10~5 atom/g and 2.2×10~6 atom/g, respectively. As calculated on the basis of the above estimates, the erosion rates of the source regions are: εBeL1=1.5×10~(-3) cm/a for the L1 period (10,000—90,000 a) and εBeL2=3.8×10~(-4) cm/a for the L2 period (130,000—190,000 a). Studies of "in situ cosmogeuic ~(10)Be" in quartz from loess at deeper levels are expected to be applied to ~(10)Be dating of loess strata.     

MORPHOLOGY EVOLUTION IN PTFE AS A FUNCTION OF MELT TIME AND TEMPERATURE Ⅰ. HIGH MOLECULAR WEIGHT SINGLE- AND MULTI-MOLECULE FOLDED CHAIN SINGLE CRYSTALS AND BAND STRUCTURES

The effect of sintering dispersed dispersion and nano-emulsion particles of high molecular weight polytetrafluoroethylene (PTFE) on a substrate as a function of "melt" time and temperature is described. Folded chain single crystals parallel to the substrate and as ribbons on-edge (with double striations), as well as bands, are produced for longer sintering times; particle merger and diffusion of individual molecules, crystallizing as folded chain, single (or few) molecule,single crystals when "trapped" on the substrate by cooling occur for shorter sintering times. It is suggested the observed structures develop with sintering time, in a mesomorphic melt. The structure of the nascent particles is also discussed.     

MECHANISM OF SULFUR POISONING AND REGENERATION METHODS FOR SUPPORTED METAL CATALYSTS Ⅰ. MECHANISM OF SULFUR POISONING OF Pd(Pt)/Al_2O_3 CATALYSTS IN H_2-O_2 REACTION

Sulfur poisoning mechanism of Pd(Pt)/Al_2O_3 catalysts for H_2—O_2 reaction was studied by means of micro-catalytic reaction chromatograph, TPR, XPS, AES, XRD and IR. The results show that the tolerance of Pd/Al_2O_3 catalysts to surfur poisoning is significantly affected by the O_2/H_2 ratio and enhanced with the increase of the ratio. In″weak″oxidizing atmosphere, the deactivation is swift and irreversible because of the active components, particularly at the surface, being seriously sulfided by S~(-2). In ″strong″ oxidizing atmosphere, the poisoning caused by S~(-2) is reversible to great extent owing to the reaction M_s—S/Al_2O_3(O_2,H_2O)/catalyst(M_s(M_sO)/Al_2O_3-SO_3-H_2O)where M_s signifies Pd or Pt on the surface. But, when the sulfate in catalyst is accumulated in large amount, it could cover or block the active sites, which may be an important cause of the catalyst deactivation in addition to the sulfidization of metal components.     

EQUILIBRIA INVOLVING COBALT(II) HALIDES AND PHOSPHINE OXIDES I. A SPECTROPHOTOMETRIC STUDY OF THE COBALT(II) CHLORIDE — TRIPHENYLPHOSPHINE OXIDE SYSTEM IN ACETONE MEDIUM

Abstract

The CoCl₂-triphenylphosphine oxide system was studied in anhydrous acetone medium, at 25.00 · 0.05 ° C, by spectrophotometry. It was found that the system comprises at least three complex species, whose over-all stability constants are: β₁ = (1.40 · 0.10) · 10⁴ M^?1, β₂ = (6.77 · 0.95) · 10⁶ M^?2, β₃ = (1.77 · 0.40) · 10⁹ M^?3. The composition of the system as well as the values of the stability constants of the complex species are in a marked disagreement with the literature data. The compatibility between the experimental data and the results obtained in the present work was confirmed by different methods.