STUDY ON SOLUBILIZATION MECHANISM IN THE SYNTHESIS OF HIGH MOLECULAR WEIGHT POLY(p-PHENYLENE TEREPHTHALAMIDE)

The salts dissolved in the amide solvent play an important role in the synthesis of high molecular weight poly(p-phenylene terephthalamide) (PPTA). The solubilization of salts was investigated in this paper. The effects of association-dissociation equilibrium of salts and the solvation of their ions as well as hydrogenbond on solubilization were discussed in some detail. The effects were attributed to cations and anions of salts respetively. Finally, the equation of solubilization was established according to the experimental results and some thermodynamic laws. The relations between molecular weight of PPTA and the solubilization were discussed.     

Thermodynamic Investigation of the Azeotropic Mixture Composed of Water and Benzene

The molar heat capacity of the azeotropic mixture composed of water and benzene was measured by an adiabatic calorimeter in the temperature range from 80 to 320 K. The phase transitions took place in the temperature range from 265.409 to 275.165 K and 275.165 to 279.399 K. The phase transition temperatures were determined to be 272.945 and 278.339 K, which were corresponding to the solid-liquid phase transitions of water and benzene, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature 298.15 K were derived from the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.     

In situ Analysis of Na and K in a Laminar Premixed Flame by Laser-induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy（LIBS） was used to in situ monitor the concentration of alkali elements in combustion environments. Particular efforts were made to optimize the temporally resolved spectra of Na and K elements. Calibration curves were constructed by relating the intensities of the specific lines to the corres- ponding elemental concentrations. The detection limits of Na and K elements were found to be temperature- dependent. The results indicate that LIBS can be a powerful tool for in situ monitoring Na and K concentrations in combustion environments.     

Imaging Array SPR Biosensor Immunoassays for Sulfamethoxazole and Sulfamethazine

A homemade array surface plasmon resonance (SPR)-based imaging biosensor was used to develop sensitive and fast immunoassays to determine sulfamethoxazole (SMOZ) and sulfamethazine (SMT) in buffer. Two conjugations of sulfonamide-bovine serum albumin (BSA) were separately immobilized on two different rows of the array chip with one row as reference. The immobilization was carried out in the instrument to monitor the quantity of the conjugations immobilized. The antibody mixed with the sulfonamide in the buffer was injected over the surface of the chip to get a relative response which was inversely proportional to the concentration of the sulfonamide in the PBS buffer. Two calibration curves were constructed and the limit of detection for sufamethoxazole in buffer was 3.5 ng/mL and for sulfamethazine 0.6 ng/mL. The stability and specificity of the antibody were also studied. The monoclonal antibody did not bind with BSA.     

Oscillating Frequency Response of a Langasite Crystal Microbalance in Liquid Phase

The frequency responses of a langasite crystal microbalance （LCM） in liquid phase were investigated. It was shown that the LCM possessed much stronger oscillating ability in liquid phase than that of the commonly used quartz crystal microbalance （QCM）. The frequency shifts of the LCM to the changes in mass loading, as well as viscosity and density of the liquid were measured. The LCM was applied to monitor the adsorption process of an ionic liquid film to ethanol vapor.     

Self-assembly of Carboxyl Functionalized Polystyrene Nanospheres into Close-packed Monolayers via Chemical Adsorption

The polyacrylic acid functionalized polystyrene nanospheres were synthesized and self-assembled into irregular, densely packed monolayers in non-aqueous media. The polymer nanoparticles were chemically adhered to substrates. The morphologies of the resulting films were investigated. The impact of the volume fraction of alcohol in the mixed solvents on the particle adsorption and fabrication of nanosphere assembled films was examined.     

Effect of organic modifiers on the capacity factor in micellar electrokinetic chromatography

Organic modifiers were effective both to extend the migration time window and to improve the separation of very hydrophobic compounds in MEKC.An iteration method was used to determine the migration time of micelles.The quantitative relationship between the capacity factor k' and the concentration of organic modifiers was derived,which was investigated experimentally.The linear solvation energy relationships (LSER) methodology was applied to MEKC,and good linear relationships between Ink' and solvatochromic parameters of 15 solutes were obtained in the presence of organic modifier in different concentrations,which indicated a new access in MEKC to predict k' from the structural parameters of solutes.The effect of column temperature T on k' was also investigated.     

KINETIC STUDY OF GAS-PHASE POLYMERIZATION OF PROPENE BY THE INHIBITION METHOD USING CARBON MONOXIDE

The inhibition method using CO to determine the active center concentration C~* in olefin poly-merization and the kinetics of gas-phase polymerization of propene were studied. The reliabilityof the method when used in gas-phase polymerization of propene is proved and the influencing fac-tor of the method is found to be the "repeating inhibition" of CO to the active centers. The C~*, the rate constant k_P and the activation energy were determined from the experimentalresults. We concluded that the C~* decreases with polymerization time and coincides with the decayrate of the polymerization.     

Mechanism study on the reactions between biphenyl and HNO_2 initiated by 355 nm irradiation in aqueous phase

The reactions taking place in the mixed solution of biphenyl and nitrous acid after it was exposed to UV irradiation were studied in this research work. The transient species were identified with the nanosec- ond transient spectroscopic technique, and the final products were ascertained by GC-MS analysis. It was shown that the OH radical, generated by the direct photolysis of nitrous acid, would attack biphe- nyl molecule to form Bp-OH adduct with a rate constant of 9.5×109 L·mol?1·s?1. The Bp-OH adduct could either react with H or be oxidized by nitrous acid to form nitrosobiphenol. The reactions between biphenyl and nitrous acid under UV irradiation in atmospheric aqueous phase were therefore sug- gested to be one promising source of nitrocompounds in the environment.     

Mechanism study on the reactions between biphenyl and HNO<Subscript>2</Subscript> initiated by 355 nm irradiation in aqueous phase

The reactions taking place in the mixed solution of biphenyl and nitrous acid after it was exposed to UV irradiation were studied in this research work. The transient species were identified with the nanosecond transient spectroscopic technique, and the final products were ascertained by GC-MS analysis. It was shown that the OH radical, generated by the direct photolysis of nitrous acid, would attack biphenyl molecule to form Bp-OH adduct with a rate constant of 9.5×109 L·mol-1·s-1. The Bp-OH adduct could either react with H or be oxidized by nitrous acid to form nitrosobiphenol. The reactions between biphenyl and nitrous acid under UV irradiation in atmospheric aqueous phase were therefore suggested to be one promising source of nitrocompounds in the environment.     

原子簇NixFe和NiFex(x=1-5)电子性质的DFT研究

More than one hundred models were designed to reflect the local structure and electronic property of Ni-Fe amorphous alloys. After calculating by DFF method, a series of configurations of clusters NixFe and NiFex （x = 1 - 5） were gained. The configurations, which possessed the lowest energies and non-imaginary frequencies, were considered the most stable optimized structures. The catalytic activity, charge and magnetic properties were analyzed and discussed. The different Fe content changed the catalytic properties of clusters through altering the value of Fermi level of every cluster. However the density of state （DOS） nearby Fermi level and average 3d orbital population of atom Ni, which were also important properties related to the catalytic activation, were little changed. Based on the Fermi level, the activity of catalyst toward hydrogenation reaction would be considered best when the ratio of Ni to Fe was close to 1. The Fermi level of clusters was far distant to the level of nitrogen in singlet state. It would be the reason why the reaction condition in ammonia synthesis and nitrogen fixation process was rigorous. When Fe atom contents were higher than 75% （NiFe3）, the electrons transferred from atom Fe to Ni, but when the ratio was decreased, the transfer was reversed. The ratio of atoms of local structure also played an important role in the aspect of electron transition. On the average 3d orbital population of atom Fe, the average magnetic moments of Fe atoms in clusters were calculated. When Fe atom contents were 50% nearly, the average magnetic moment achieved the highest point.     

Transformation of chlorine in NaCl-loaded Victorian brown coal during the gasification in steam

This study is to examine the changes in Cl volatilizations and chemical forms in NaCl-loaded Victorian brown coal during gasification in steam at 800 ℃ using Cl K-edge X-ray absorption near-edge structure(XANES) spectroscopy.The char samples were prepared in a novel one-stage fluidised-bed / fixed-bed quartz reactor at a fast heating rate.The samples were then collected and sealed in an argon-filled bag in order to minimise possible oxidation of char and Cl by air prior to analysis by XANES.Char-steam reactions were found to significantly affect the transformation of Cl,including the possible formation of chlorine-containing organic structures.On the other hand,volatile-char interactions during the gasification appeared to enhance the Cl retention and prevent the formation of organic chlorine compounds in chars.     

SOME OBSERVATIONS ON DYNAMIC PROPERTIES OF RECEPTIVE FIELD ORGANIZATION OF COMPLEX CELLS IN CAT VISUAL CORTEX

The dynamic properties of discharge fields (DFs) of the complex cells in areas 17 and 18 of cat'sbrain were observed. The sequence of activation for different areas in the DF indicated a concentric ar-rangement of latency distribution. The DE organization was proved to be dependent closely cn velocityof stimulus movement. Twin-or triple-DFs were found for some cells, each responded selectively to oneof the opposite directions of movement.     

EFFECT OF PROCESSING METHOD ON THE IMPACT STRENGTH OF POM/TPU/CaCO3 TERNARY COMPOSITES

Polyoxymethylene （POM）/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane （TPU） and inorganic filler, namely, CaCO3, were used to achieve balanced mechanical properties of POM. The dispersion and phase morphology of POM/elastomer/filler composites were found to depend largely on processing method, CaCO3 content in masterbatch and the filler size. Two processing methods were employed to prepare POM/elastomer/filler ternary composites. One is called the one-step method, in which elastomer and the filler directly melt blended with POM matrix. The other is called the two-step method, in which the elastomer and the filler were mixed to get masterbatch first, which was then melt blended with pure POM of different content. The effect of phase morphology and processing method on impact strength was investigated. It was found that the two-step method results in an increase in impact strength but not for the one-step method. Additionally, the impact strength of POM ternary composites decreases with the increase in the size of CaCO3 particles.     

Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of Shenzhen in summer and in winter

Two field measurements for atmospheric fine particles were conducted in Baoan district of Shenzhen during the summer and winter in 2004. Totally 30 sets of 24 h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal varia- tions and secondary pollution characteristics of fine particles during the sampling periods were dis-cussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in Shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 35 μg·m-3 and 57 μg·m-3, respectively, and those in winter were 99 μg·m-3 and 135 μg·m-3, respec-tively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 137%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in Shenzhen. During the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. During the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol compo-nents in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from South China Sea in summer, and the air quality was good. The prevailing wind in winter was from Mainland China to the north, and the polluted air mass led to poor air quality.     

STUDIES ON THE PHOTOCHEMICAL REACTION OF TERTIARY AROMATIC AMINES AND ALIPHATIC HALIDES——STRUCTURE OF THE PRODUCT AND MECHANISM OF THE REACTION

The photochemical reaction of aromatic amines in the presence of aliphatic halides and molecular oxygen were studied. There is a very obvious structural effect of amines on the photoreactions, and the purple products, formed only in the tertiary aromatic amines system, were proved to be amiuium radical salts, e. g. CH_3—(CH_3)_2Cl-by moans of UV, NMR and ESR spectroscopies electronic conductivity and chemical analysis. The purple product can oxidize the adrenaline to adrenochrome. The mechanism of the photoreaction and the oxidation were discussed.     

IDENTIFICATION OF A RICKETTSIA-LIKE ORGANISM AND ITS INTERCELLULAR MOVEMENT IN SYSTEMATICALLY INFECTED WHEAT PLANT

According to the electron microscopic observation the wheat yellow curl-leaf disease wascaused by a rickettsia-like organism (RLO). The morphology and structure of the pathogenand its distribution within the host plant were of typical characteristics of the RLO. RLO_Swere seen in the phloem and xylem of the host plant. In xylem elements RLO particleswere closely related to electron-dense materials spreading in them. Some channels wereformed in the cell walls of protoxylem, and sometimes in the cell walls of mature xylem ele-ments which were eroded. RLOs entered adjacent cells and intercellular spaces via thesechannels. A large number of RLOs were seen in sieve elements and they could get intoadjacent sieve elements via sieve pores. The places of intercellular movement of RLOs weremostly in the plasmodesmata-dense areas or pit fields where the primary cell walls amongplasmodesmata were dissolved to form some channels by the invasion of RLOs. And theforming of less intercellular channels did not relate to plasmodesmata and pit fields. Basedon these results the mechanism of systematical infection of host plant caused by the RLO isdiscussed in this paper.     

Kinetic of Adsorption of Urea Nitrogen onto Chitosan Coated Dialdehyde Cellulose under Catalysis of Immobilized Urease

The adsorption of urea nitrogen onto chitosan coated dialdehyde cellulose (CDAC) under catalysis of immobilized urease in gelatin membrane (IE) was studied in batch system. The pseudo first-order and second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The experimental data fitted well to the second-order kinetic model.     

ESR STUDY OF PLASMA-TREATED POLYTETRAFLUOROETHYLENE FILMS

The plasma treatment of polytetrafluoroethylene (PTFE) films was carried out in a capacitively coupled reactor with external electrodes. The free radicals generated in the process of treatment were detected by ESR techniques. The ESR spectra tended to indicate that the free radicals of the pLasma-treated PTFE film sample were turned into peroxy radicals on exposure to air. The extrema separation (W) of the ESR spectrum of the peroxy radical increased with the lowering temperature and underwent a sudden change within the temperature range of 170 to 190K. The ESR spectrum observed at 77K was quite different from that observed at room temperature. Finally, the effects of treatment time, input power and system pressure on radical concentration of the treated samples were studied. The attenuation of the peroxy radical at room temperature was also investigated.