The Character of Photo-electrochemistry of Palladium Implanted TiO_2 Nano-crystalline Electrode

A new electrode was prepared by using Pd implanted into nano-crystalline TiO2 and the character of photo-electrochemistry of implanted electrodes was investigated. The energy band structure of nano-crystalline TiO2 has not changed after implantation with Pd. The photo-current (i(ph)) of palladium implanted TiO2 nano-crystalline electrode is larger than that of pure TiO2 nanocrystalline electrode.

Study of Transport and Separation of Rare Earth Ions through the Emulsion Liquid Membrane of Bis(2,4,4-trimethylpentyl)phosphinic Acid-Span 80-Toluene

It is indicated from a study of transport of rare earth ions through the emulsion liquid mem- brane of bis(2,4,4-trimethylpentyl)phosphinic acid-Span 80-toluene that transporting rare earth ions com- pletely and rapidly was realized under the optimum experimental conditions:1.0×10^(-3)～3.0×10^(-3)mol/L bis(2,4,4-trimethylpentyl)phosphinic acid and 2%～4%(W/V)Span 80 in toluene solution as membrane phase,0.50～2.0 mol/L HCl as inner phase,rare earth ion solutions with pH 3.5～5.0 as outer phase.Ac- cording to the differences of transport behavior for rare earth ions,it is possible to separate rare earth ions from mixed solutions of rare earth ions by this liquid membrane system.

STUDIES OF THE INITIATION MECHANISM OF VINYL POLYMERIZATION WITH THE SYSTEM PERSULFATE/N-ALKYL SUBSTITUTED ETHYLENEDIAMINE DERIVATIVES

Effects of N-alkyi substituted ethylenediamine derivatives on vinyl polymerization using persulfate as initiator were studied. The apparent kinetic equations and overall activation energies of acrylamide polymerization were determined using the above mentioned system as initiator. The promoting activities of different diamine derivatives on vinyl polymerization are in the order of tertiary diamine>secondary diamine>primary diamine. Diamines having methyl groups as the substituent on their nitrogen atom possess higher promoting activity than that of having larger alkyl groups. The initial free radicals produced through the redox reaction of persuifate and diamines were studied by spin strapping technique and ESR spectroscopy. The results obtained confirm the fact that the initial free radicals of the diamine species can initiate vinyl polymerization and become the amino end group of the resulting polymers.

STUDIES ON THE INITIATION MECHANISM OF ORGANIC PEROXIDE AND N-METHACRYLOYLOXYETHYL-N-METHYL ANILINE IN METHYL METHACRYLATE POLYMERIZATION

The initiation mechanism of methyl methacrylate (MMA) polymerization by organic peroxide and polymerizable aromatic tertiary amine such as N-methacryloyloxyethyl-N-methyl aniline (MEMA) binary system has been studied. The kinetics of polymerization of MMA and the ESR spectra of organic peroxide/MEMA system were determined. Based on the ESR study and the end-group analysis by UV spectra of the polymer formed, the initiation mechanism is proposed.

ISOLATION AND IDENTIFICATION OF β-N-OXALO-L-α,β-DIAMINOPROPIONIC ACID AND ITS ISOMER α-N-OXALO-L-α,β-DIAMINOPROPIONIC ACID FROM PANAX SPECIES

The neuroexcitotoxic nonprotein amino acid β-N-oxalo-L-α, β-diaminopropionic acid (β-N-ODAP)and its isomer a-N-oxalo-L-α, β-diaminopropionic acid (α-N-ODAP)in Panax ginseng C. A. Meyer(cultivated ih Northeastern China), Panax quinquefolius L., Panax notoginseng F.H. Chen (cultivated in Southwestern China), Korean red ginseng and Jilin red ginseng were isolated and identified. Efficient separation and purification methods for β-N-ODAP and α-N-ODAP were developed.

Identification and determination of (+)-sesamin in Semen Cuscutae by capillary GC and GC-MS

(+)-Sesamin was found in Semen Cuscutae for the first time. A rapid and simple approach for the analysis of(+)-sesamin in different sources of Semen Cuscutae is proposed, which used GC-FID for the determination of(+)-sesamin and CC-MS for its identification. The result suggested that this approach could be used to identify Semen Cuscutae from various sources based on the different content of(+)-sesamin in them.

ASPHERICITY AND PROLATENESS OF LINEAR AND CIRCULAR MACROMOLECULES

The shape asymmetry of gaussian models of linear and circular macromolecules has been numerically investigated in terms of asphericity and prolateness parameters. These parameters are found to decrease with increasing length for the macromolecule either confined to a plane or in three dimensions. The effect of dimensionality on these parameters is visible only for low dimensions and is generally weak. As dimensionality goes to infinity, it is found that asphericity and prolateness for both chains and rings approach slowly yet descendingly values of corresponding asphericity and prolateness factors, with the exception of the chain which shows a minimum value of asphericity when the embedding space has a dimensionality of four.

Pho to luminescence and Photoluminescence Excitation of Si Aerogels Prepared by Supercritical Drying

Si aerogel,the porous silicon with ultra high porosity,has been prepared by the technique of anodization followed by supercritical drying.Its photoluminescence,photoluminescence excitation and morphological features exhibit novel characteristics from those of the conventionally anodized porous silicon.We observed the differences between the Si aerogels made&om(100)and(111)crystalline Si.

Optical Limiting Performance of a Crystal Violet Cation Fulleride Salt

Optical limiting properties of a crystal violet cation fulleride salt dissolved in tetrahydrofuran have been studied by using 10 ns,532 nm laser pulses.The fluence-dependent transmissivity measurements were performed on the samples with the same concentration and different path lengths in a collimated optical set-up.For comparison,the fluence-dependent transmissivities of fullerene C_(60) and crystal violet solutions were also measured under the same linear transmissivity.The nonlinear optical limiting effect of the fulleride salt in tetrahydrofuran was even slightly stronger than that of C_(60) in toluene.

Synthesis of Pyrrole-Imidazole Polyamide

One simple and versatile method is established far the synthesis of DNA recognition molecules-polyamides containing alternating N-methylpyrrole and N-methylimidazole without necessitating NH2- group protection.

STUDIES ON THE INDOLE ALKALOIDS OF GELSEMIUM ELEGANS

The modified Hofmann degradation of koumine(1) has proved abortive. The struture and stereochemistry of the main product(3) were deduced by spectral methods and confirmed by X-ray diffration analysis. From the roots of Gelsemium elegans, dihydrokounine was first isolated as a natural product.

RADICAL POLYMERIZATION OF N, N-DI(2-2'-METHYL-ACRYLOYLOXY-PROPYL)-PARA-TOLUIDINE FUNCTIONAL MONOMER

Functional monomer (MP)_2PT having tertiary aromatic amino group was systhesized from the reaction of N, N-di (2-hydroxypropyl)-p-toluidine with 2-methyl acryloyl chloride. In the presence of organic peroxide, the radical polymerization of (MP)_2PT in toluene took place. The kinetics of (MP)_2PT polymerization and the ESR spectra of LPO-(MP)2PT-MNP systems were determined respectively.

THE EFFECTS OF N-2-HYDROXYETHYL-N-METHYL-p-TOLUIDINE ON METHYL METHACRYLATE RADICAL POLYMERI-ZATION AND ACRYLONITRILE PHOTOINDUCED POLYMERIZATION

The effects of N-2-hydroxyethyl-N-methyl-p-toluidine (HMT) on MMA polymerization using organic peroxide as an initiator and on AN photoinduced polymerization have been investigated respectively. The kinetics of polymerization and the overall activation energy of polymerization were determined. Based on kinetics study and the end group analysis of the polymer obtained by UV spectrum method, the initiation mechanism is proposed.

INVESTIGATION ON THE PHASE DIAGRAM OF TERNARY SYSTEM LaCl_3-SrCl_2-LiCl

Abstract: The phase diagram of ternary system LaCl3 - SrCl2 - LiCl has been investigated by means of DTA. It was found that there were three fields corresponding to primary crystallization of LaCl3, SrCl2 and LiCl respectively, three univeriant curves related to the secondary crystallization, a ternary eutectic E (46.8% LaCl3, 25.4% SrCl, 30.0% LiCl; 469℃) in the system. A ternary reaction occurred in the system:L = LaCl3 + SrCl2 + LiCl

PREPARATION OF LIQUID CRYSTALLINE COPOLYESTERS WITH SPACERS BASED ON BISPHENOL-A,BISPHENOL-S OR POLYSULFONE BY DIRECT POLYCONDENSATION

Four series of copolyesters were synthesized by direct polycondonsation reaction between aromatic dicarboxylic acids and bisphenols by using tosyi chloride and N, N-dimethylformamide ( DMF ) in pyridine under mild conditions. The electron-rich hydroxyl groups of bisphenols favoured the polycondensation reaction and the order of relative reactivities of bisphenols is as follow:bisphenoI-A> hydroquinone ～ bisphenol-S> chlorohydroquinone. The mesomorphic properties of copolyesters were examined by birefringence under polarizing microscope, melt transparency. DSC and X-ray diffraction. The minimum molar fraction of mesogenic units needed for the appearance of liquid crystallinity is not higher than 0. 1 despite of the different varieties and lengths of the spacers studied.

SYNTHESIS OF MESOGENIC POLYESTERS WITH 2-DICHLOROMETHYLHYDROQUINONE MOIETIES

A series of novel mesogenic polyesters with 2-dichloromethylhydroquinone moieties were synthesized by polycondensation of the novel diacyl chloride monomer 2-dichloromethyl-1,4-bis (4'-chloroformylbenzoyl) oxybenzene (I) with alpha, omega-polymethylenediols including ethylene glycol, 1,4-butanediol, 1,6-hexanediol and 1,10-decanediol. The diacyl chloride monomer was synthesized by simultaneous transformations of both the carboxy and formaldehyde groups of 2-formyl-1,4-bis (4'-carboxybenzoyl) oxybenzene into acyl chloride and dichloromethyl groups respectively. The syntheses of the monomer (I) and the polymers were reported.

Photostimulated Luminescence and F-centers of Sr_3Ca_2(PO_4)_3X:Eu^(2+)(X=F,Cl,Br)

This paper reports the F-centers and photostimulated luminescence of Eu^(2+)-activated Sr_3Ca_2(PO_4)_3X crystals.The influence of various halide ions on the F-centers and their energy level is discussed.The mechanism for the photostimulated luminescence and valence change of Eu ion in that process have been investigated.

SPECTROPHOTOMETRIC STUDY OF DDQ CHARGE-TRANSFER COMPLEXES WITH 1,10-PHENANTHROLINE AND ITS DERIVATIVES

1,10-phenanthroline and its derivatives can form charge-transfer complexes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ).The absorption spectra and conditions of complex formation,such as the reaction time,the quantity of DDQ, and the solvents, have been studied.After the HMO calculation of phenanthrolines,the molar absorptivities were found to depend on the substituents on the phenanthroline rings.

Luminescent Properties of Eu^(3+) and Bi^(3+) and Their Interaction in LaBO_3 and GdBO_3

Under the excitation of UV light and cathode ray,the dependence of the excitation and emission spectra and luminescent lifetime of Eu^(3+)and Bi^(3+)on composition and structure in LABO_3 and GdBO_3 has been stu- died.The results indicate that the emission spectra of Eu^(3+)in LaBO_3 with aragonite structure and in GdBO_3 with YBO_3 structure are quite different.Under 254 nm excitation,Eu^(3+)emission is sensitized by Bi^(3+)in GdBO_3 matrix.In other case Eu^(3+)emission is quenched by Bi(3+).

STUDIES ON THE INITIATION MECHANISM OF CERIC ION AND ACETYLACETONE REDOX SYSTEM IN VINYL POLYMERIZATION

The initiation mechanism of acrylamide (AAM)polymerization using ceric ion/acetylacetone system as an initiator has been studied. The redox polymerization was revealed by the low value of overall activation energy of AAm polymerization. The structure of free radicals formed from above-mentioned initiation sytem were detected by radical trapping and ESR spectra techniques and the end groups of polymers obtained were determined by FT-IR spectra analysis method. Based on these results the initiation mechanism is proposed.