QUANTUM SIZE EFFECT ON PHOTOCATALYSIS OF NANOMETER SEMICONDUCTOR

Colloidal semiconductor is of interest as photocatalyst for various pro-cesses.A particular attention has been given to the so-called Q-particles ofsemiconductor witn respect to a“quantum size effect”[1].Recently,we re-ported that 1 nm ZnS particles could be obtained by embedding them Into β-cyclodextrin( BCD) cavities[2]and the resulting ZnS/BCD inclusion complexshowed much higher efficiency in simultaneous photocatalytic production ofhydrogen and ethylene glycol from aqueous methanol solution[3].In thiswork,we briefly present experimental evidence for the size quantization ef-fect of such small ZnS particles on the photocatalysis.     

EFFECT OF PARTICLE SIZE ON THE FILMING PROCESS OF POLYSTYRENE LATEX STUDIED BY AFM

The film formation process of micro-PS particles (diameter 742 nm) and nano-PS particles (diameter 29 nm) wasstudied by atomic force microscopy and differential scanning calorimetry. During a step heating process, the particles wereannealed for 0.5 h at each selected temperature. It was found that the deformation and interdiffusion temperatures of themicro-PS particles are ca. 120-130℃ and 140-150℃, that of the nano-PS particles are 90℃ and 100-110℃ respectively.The DSC traces of nano-PS particles showed that there was an exothermic peak near T_g after annealing for 0.5 h at theselected temperatures below 90℃; otherwise, the exothermic peak disappeared after annealing at 100℃ or above. Comparedwith the micro-PS pedicles, the sintering process of nano-PS particles occurs at much lower temperature determined by theconfined state of polymer chains with higher conformational energy in nano-particles, and completes in a much narrowertemperature range driven mainly by the larger total surface energy.     

PARAMETERS AFFECTING PARTICLE SIZE OF POLYBUTYL-ACRYLATE MICROGELS

The factors affecting particle size of reactive microgels formed during the self-emulsifying copolymerization of unsaturated polyester (UP)with butyl acrylate (BA)have been studied. The parameters discussed are: the proportion of the UP in the monomer mixture, the molecular weight and the carboxyl value of the UP, the phase ratio, the electrolyte concentration and the polar solvent additive. The seeding emulsion polymerization is discussed as well.It turned out that the particle size of the reactive microgels can be controlled in a definite range by changing the experimental conditions. However the particle size distribution becomes broader as the average diameter increases. It is suggested that the agglomeration of primary particles plays an important role during the growth of microgel particle.     

STUDY ON THE ADSORPTION BEHAVIOR OF Pb（Ⅱ） ON NANOMETER ATTAPULGITE BY FAAS

The adsorptive behavior of nanometer attapulgite modified by acid to Pb（Ⅱ） was investigated by flame atomic absorption spectrometry （FAAS） in this paper. The mainly effect parameters ott the adsorptive efficiency of Pb（Ⅱ）, such as the acidity of the solution, the amount of attapulgite, oscillation time and static time were studied. Also the influencing factors of the recovery efficiency of Pb（Ⅱ）, including the concentration of hydrochloric acid, the volume of hydrochloric acid, oscillation time and static time were investigated. The adsorptive capacity of Pb（Ⅱ） on nanometer attapulgite was 26.5mg/g and the adsorptive capacity of first cycle and second cycle regenerated nanometer attapulgite were 26.5mg/g and 26.3mg/g, respectively. The results obtained indicated that the regenerated effect was good.     

XPS STUDY ON THE ROLE OF CO_2 IN LOW-PRESSURE METHANOL SYNTHESIS

Surface characterization of CuO-ZnO-Al_2O_3 catalysts for low pres-sure methanol synthesis was carried out by using X-ray photoelectron spec-troscopy(XPS)combined with reaction chamber under simulated industrialoperating condition.Under the reduction and reaction conditions,no stableCu~(2+) or Cu~+ ions were found,only Cu~0 species was detected.ZuO could be re-duced with result of forming oxygen-deficient structure ZnO_x(X<1)andoxygen vacancy on the surface.The presence of enough amount of CO_2 infeed gas enhanced copper dispersion.It is believed that highly dispersed Cu~0 in intimate contact with ZnO is one of the active components for methanol syn-thesis and the optimal structure of the active unit is Cu——Zn—O(“□”is oxygen vacancy).It is proposed that the main role of CO_2 is to establish anoxidation potential of syngas so as to accelerate the oxidation-reduction cyclebetween Cu~0 and Cu~(δ+)/or Cu~+ during methanol synthesis as well as to preventCu~0 crystallites from aggregating and thus to maintain the catalyst in high ac-tivity and have long life.     

ROLE OF SYNTHETIC ANTIOXIDANTS ON THE AGING PROPERTY OF ELECTRON BEAM IRRADIATED NATURAL RUBBER

The aging property of radiation vulcanized natural rubber was studied using various kinds of antioxidants. Aging test was done at 100℃ for various lengths of time. It was found that some antioxidants are excellent in preventing the oxidative degradation of the irradiated rubber. DAH (2,5-di-tert-amylhydroquinone) CBP (2,2‘-dihydroxy-3,3‘-di(-methylcyclohexyl)-5,5‘-dimethyl diphenyl methane) P16 (tris(2,4-di-tert-butylphenyl)phosphate) in a proportion of (1:0.5:0.5) was found to be the best combination to achieve 100% retention of tensile strength.     

THE FUNCTION OF La（III） ON ＂ION－GATE＂ OF THE GLUTATHIONE MONOLAYER GOLD ELECTRODE

ＴＨＥ ＦＵＮＣＴＩＯＮ ＯＦ Ｌａ（ＩＩＩ） ＯＮ ＂ＩＯＮ－ＧＡＴＥ＂ ＯＦ ＴＨＥ ＧＬＵＴＡＴＨＩＯＮＥ ＭＯＮＯＬＡＹＥＲ ＧＯＬＤ ＥＬＥＣＴＲＯＤＥ￥ＺｉＷｅｉＪＩＡＮＧ；ＷｅｎＫｕａｎＸＩＮ；ＸｉａｏＸｉａＧＡＯ（Ｄｅｐａｒｔｍｅｎｔ...     

THE ROLE OF LATTICE AND GASEOUS OXYGEN ON THE OXIDATIVE COUPLING OF METHANE STUDIED BY A PULSE REACTION TECHNIQUE

A comparative study of the role of lattice and gaseous oxygen in theoxidative coupling of methane over Na~ /Cao and Ca_xSr_(1-x)TiO_3 perovskiteoxide catalysts was performed by using a pulse reaction technique with CH_4,O_2 and mixtures of CH_4and O_2.It was found that there is an oxygen species onthe Surface of Cao which is active only for the total oxidation of methane at thereaction temperature.These oxygen species.once reacted with methane andconsumed,can be regenerated by the adsorption of oxygen molecules from thegas phase or by the migration of the lattice oxysen from the bulk onto thesurface.In contrast,no such oxygen species and no reaction can be detected bymethane pulsed over Ca_xSr_(1-x)TiO_3perovskite oxide catalysts.Na~ can heavilysuppress the non-selective oxygen species on the surface,and When 5mol%Na~ was incorporated onto the surface of Cao,the sample showed no reactivityto methane.When oxygen exists in the gas phase,or the pulse containsmethane and oxygen,the reaction over(Cao is mai     

PREPARATION OF PARTICLE SIZE NARROWLY DISTRIBUTED LOW-DENSITY STYRENE DIVINYLBENZENE COPOLYMER MICROBEADS

1. INTRODUCTION Micro-particle polymers have found their application in bioengineering, electronic and chemical industry [1~3], chemical analysis and some other fields. As a kind of carrier both the density, the particle sizes are very important char…     

ROLE OF AMINIUM RADICAL IN THE INITIATION OF VINYL POLYMERIZATION

Amine is usually considered as antioxidant, inhibitor or chain transfer agent. Aromaticsecondary amine and hindered piperidine compounds are used as antioxidant and light stabi-lizers. Aromatic and aliphatic amines themselves will act as chain transfer agents in vinylpolymerization. On the other hand it is also well known that tertiary amines are used either     

DYNAMIC MONTE CARLO STUDY ON THE CORRELATION BETWEEN SHAPE AND SIZE OF LINEAR POLYMER CHAINS

The correlation between shape and size of linear chains on the simple cubic lattice is investigated using a dynamicMonte Carlo technique. A positive correlation between the asphericity parameter A and the square of the end-to-end distanceR~2, as well as that between A and the square of the radius of gyration S~2, is found for both RW and SAW chains, indicatingthat a chain conformation of small size is usually more spherical than one of large size. The result can explain why the shapeof the SAW chain deviate much more from a sphere than that of the RW chain, and can also explain the similar dependenceof size and shape on chain stiffness and on the distance of the first bead of a chain from an infinitely large flat surface.     

A STUDY ON THE BEHAVIOUR AND MECHANISM OF EXTRACTING GOLD(Ⅲ)USING PTSO

PTSO is abbreviated from di-P-tolyl Eolphoxide having a>S=0 group and is a neutral extractant.We have studied the behaviour and conditions of the separation of Au(Ⅲ) from other elements on a column packed with the silica gel loaded with PTSO and have found that PTSO is a new stationary phase with extremely high selectivity for the separation and concentration of gold.However,the application of PTSO to the solvent extraction has not bean reported yet.We first studied the behaviour and mechanism using PTSO to extract gold by atomic-absorption spectrophotometry,ultra-violet spectrophotometry and infra-red spectrophotometry.The possible structure of the extractive formed from PTSO and Au(Ⅲ) is suggested.     

STUDIES ON THE CONSTITUENTS OF THE ROOTS OF SCUTELLARIA PLANIPES

ＳＴＵＤＩＥＳＯＮＴＨＥＣＯＮＳＴＩＴＵＥＮＴＳＯＦＴＨＥＲＯＯＴＳＯＦＳＣＵＴＥＬＬＡＲＩＡＰＬＡＮＩＰＥＳ￥ＹｏｕｓＹｕＺＨａＮＧ；ＸｉａｎＬＩ；ＹｕｎＺｈｅｎＧＯＵ（ＳｈｅｎｒｅｎｇＰｈａｒｍａｃｅｕｔｉｃａｌＵｎｉｖｅｒｓｉｔｙ，Ｓｈｅｎａｎ...     

STUDY ON THE ANALYTICAL MODEL OF DECAY OF MESOSCALE EDDY ON THE CONTINENTAL SHELF

Observations indicate that the motion of an oceanic mesoscale eddy entering the conti-nental shelf will quickly decay. This shows that the surface area of the eddy continuouslyexpands, and the rotational angular velocity gradually decays with time. Starting from avorticity equation for a vertically stratified, horizontally uniform fluid the above process isdynamically analyzed in this paper. Under the condition to consider the Ekman pump effectof the upper and lower boundary layers and side friction, the analytical models for thesurface area expansion and angular velocity decay of the eddy are deduced.     

STUDY ON THE EFFECT OF POLYSTYRENE SULFONIC ACID MACROMOLECULES ON THE POLYMERIZATION OF ACRYLAMIDE

The effect of polystyrene sulfonic acid (PSSA) macromolecules on the polymerization of acrylamide (AM) has been studied. It was found that the rates of polymerization of AM were greatly increased in the presence of PSSA in the polymerization system.The maximum value of the rate of polymerization of AM was obtained when the ratio of [—SO_3H]: [AM] reached 3:1. When the insoluble crosslinked PSSA was used instead of the soluble one, this effect decreased considerably. The interaction between molecules of PSSA and AM was determined by infrared spectroscopy, elementary analysis and X-ray photoelectron spectroscopy. The combination form, —SO_3-NH_3~ CO—, formed between sulfonic group and amide group was found to be existed since the infrared absorption band of —NH_2 shifted from 3400cm~(-1) to 3150 cm~(-1), the binding energy of electron N_(18) changed from 399.7 eV to 401.3 eV, and the atomic ratio of N to S of the products was similar to the ratio of reagents. Based on these experimental results, the mechanism of AM polymerization in the presence of PSSA is proposed. The initial step is the combination of AM with sulfonic group to form —CONH_3~ , then followed by polymerization on the PSSA macromolecule. The role of PSSA on the polymerization of AM is discussed.     

THE PREPARATION AND CHARACTERIZATION OF ZnO-Ag CORE-SHELL ULTRAFINE PARTICLE

ＴＨＥ　ＰＲＥＰＡＲＡＴＩＯＮ　ＡＮＤ　ＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮ　ＯＦ　ＺｎＯ－Ａｇ　ＣＯＲＥ－ＳＨＥＬＬ　ＵＬＴＲＡＦＩＮＥ　ＰＡＲＴＩＣＬＥＴＨＥＰＲＥＰＡＲＡＴＩＯＮＡＮＤＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＺｎＯ－ＡｇＣＯＲＥ－ＳＨＥ...     

THE STUDY ON EFFECT OF PARTICLE SIZE IN BOTANICAL STANDARD SAMPLE ANALYSIS BY SLURRY SAMPLING AND FLUORINATION ELECTROTHERMAL VAPORIZATION（ETV）－ICP－AES

ＴＨＥＳＴＵＤＹＯＮＥＦＦＥＣＴＯＦＰＡＲＴＩＣＬＥＳＩＺＥＩＮＢＯＴＡＮＩＣＡＬＳＴＡＮＤＡＲＤＳＡＭＰＬＥＡＮＡＬＹＳＩＳＢＹＳＬＵＲＲＹＳＡＭＰＬＩＮＧＡＮＤＦＬＵＯＲＩＮＡＴＩＯＮＥＬＥＣＴＲＯＴＨＥＲＭＡＬＶＡＰＯＲＩＺＡＴＩＯＮ（ＥＴＶ）...     

THE EFFECTS OF IRRADIATION ON THE THERMAL PROPERTIES OF SEMI-CRYSTALLINE POLYAMIDES

Irradiation crosslinking of semi-crystalline polyamides was performed by high energy electronswith various dosages. It is known that the melting behavior of the polymers after irradiation is acomplex phenomenon. In company with the wide angle X-ray diffraction and DSC data of irradiatedand unirradiated polyamides it is possible to develop the local order and perfection of the crystallinitiesslightly which resulted from introduction of intermolecular crosslinking in amorphous region, incl-uding in amorphous-crystalline interface and crystalline defect regions due to irradiation. It canbe explained that slight increase of melting temperature (T_m) and heat of fusion (△H_f) with increasingdosage for both of higher crystallinity nylon 4 and nylon 6. For irradiated lower crystallinity nylons,in contrast, the T_m and △H_f decrease obviously with increasing dosage. In this case, radiation cross-linking "freeze in" the pre-existing morphology, and then the prevention for reorganization duringheating is a dominant effect. The T_m from the second melting for all of the samples were depressed,corresponding with Flory theory. Therefore the crosslinks imposed on the molecules restrainedthe molecular mobility, and that not only depresses the crystallinity but also increases the imperfec-tion of crystallites when the radiated polymer melted and then recrystallized. These are also reflectedin the depression of heat and entropy of fusion as well as the appearance of double melting peakson the DSC thermograms.     

THE RETICAL STUDIES ON THE THERMOLYSIS OF THIETANE

The mechanism of the thermolysis of thietane to form ethyleneand thioformaldehyde has been studied by using ab initio SCF MO methodat STO-3G* and 3-21G* level.It has been found that there are twopossible stepwise pathways.One is to break C-C bond firstly,while theother is to break C-S bond at first.The cleavage of C-S bond is pre-ferred over that of C-C bond.