MONTE CARLO SIMULATION ON AQUEOUS SOLUTION OF BIOLOGICAL MOLECULES——ALANINE SOLUTION

The Monte Carlo simulation is performed for a cluster consisting of a neutral alanine molecule surrounded by 56 water molecules. The average water-water and alanine-water interaction energies are found. The space surrounding the alanine molecule is divided into three regions, where the central atoms are C' atom for the earboxyl group region, N atom for the amino group region and C~β atom for the methyl group region. The water-water and water-alanine interaction energies as functions of the distance between the oxygen atom in a water molecule and the central atom in each region are calculated. In each region the orientational correlation function for the dipole moments of water molecules, the radial distribution function for the oxygen and hydrogen atoms of water molecules are evaluated. In addition, the numbers of water molecules in the first solvation shells of each region and of entire alanine molecule are also counted.     

RADIAL DISTRIBUTION FUNCTION OF cis-1,4-POLYBUTADIENE BY ELECTRON DIFFRACTION

The interatomic distance function of rareearth catalyzed cis-1,4-polybutadiene was studied by" radial distribution function (RDF) derived from electron diffraction. Two intramolecular peaks and three interrnolecular peaks have been found on the RDF. The appearance of such a number of intermolecular maxima on the RDF can be explained by the local parallel packing of long molecular chains of the amorphous polymers.     

MECHANISM SIMULATION OF PROPANE AMMOXIDATION ON CONIPLEX CATALYST SURFACE BY MONTE CARLO APPROAC

IntroductionPropaneanllllo\idatiOllisollcoftile1hostprolllisillgprocessesbecauseoftilepriceSllpcriorlt'ofpropanetopropcllciIIForstICllallo\'crallreact1Oll.anllllti-colllpollclltcatal\'st(s[lcllasV/Sbs}stclll)isrequiredtoacti\'atcthercactallts\'llcrcaconlp…     

APPLICATION OF MONTE CARLO METHOD TO REMOTE SENSING OF HUMIDITY

In this paper, the principles and technique of obtaining the vertical profile of atmospherichumidity with the Monte Carlo method are introduced, Samples (463 in total) for Beijing,Shanghai and Haikou in winter and summer during the years 1970--1975 are tested numerical-ly. The inferred relative humidity profiles re in good agreement with the observations byradiosonde in the lower atmospheric layer. The mean relative errors are about 10% andwithin 30% in the lower atmosphere and in the upper troposphere respectively. The char-acteristics of kernel functions in microwave channels and some factors which affect theaccuracy are also discussed.     

STUDY ON THE SEQUENCE STRUCTURE OF SBR BY 13C-NMR METHOD Ⅵ MONTE CARLO SIMULATION OF THE SEQUENCE OF SBR

A program of Monte Carlo simulation of binary copolymerization for E-SBR (emulsion polymn. SB rubber) was made according to the terminal model. The simulation results obtained by this program were in good agreement with those experimental ones. A detail microstructure information of E-SBR molecular chain has been provided.     

STUDY ON THE THERMODYNAMIC PROPERTIES OF ADSORPTION OF ETHYL BENZOATE AND DIETHYL PHTHALATE BY PHENOLIC RESIN ADSORBENTS

This paper presents experimental observations on the adsorption of individual solutes by a simple thermodynamic framework, and the equilibrium adsorption of ethyl benzoate and diethyl phthalate on phenolic resin adsorbent in hexane solutions within the temperature range of 293-313 K. The experimental results show that the Freundlich adsorption law is applicable to the adsorption of ethyl benzoate and diethyl phthalate on the adsorbent, since all the correlative factors R‘are larger than 0.99. The negative values of all the isosteric adsorption enthalpies for ethyl benzoate and diethyl phthalate indicate that they undergo exothermic processes, while their magnitudes (19-28 kJ/mol) manifest a hydrogen bonding sorption process. Other thermodynamic properties: the free energy changes and the entropy change associated with the adsorption have been calculated from the Gibbs adsorption equation and the Gibbs-Helmholtz equation.     

INTROMISSION OF WATER-REPELLENT AND HYDROSCOPIC PROPERTIES SIMULTANEOUSLY TO PP BY PLASMA DISCHARGE METHOD

Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric (PP-g-AA) and polypropylene membrane were reported. The extents of grafting were controlled by the plasma and polymerization condition. Hexadecyltrimethyl ammonium bromide was then coupled with the carboxyl group of PP-g-AA to obtain a polyion complex (PIC). At last, CF4 plasma was used to give PICs hydrophobic property. The moisture regain and water-repellency of the processed PICs was investigated. The surfaces were characterized using ATR FT-IR and XPS. The result indicates that the products have very high ability to adsorb moisture, even better than cotton fiber. At the same time, the products show excellent hydrophobic property, which can‘t be wetted by those reagents whose surface tensions were higher than 327mN/m.     

PRINCIPLE OF REMOTE SENSING OF ATMOSPHERIC AEROSOL SIZE DISTRIBUTION BY COMBINED SOLAR EXTINCTION AND FORWARD SCATTERING METHOD AND NUMERICAL EXPERIMENT

In this paper, the principle of inverting aerosol size distribution by solar spectral extinc-tion-forward scattering measurements is proposed and analyzed. Two methods of inversion——the segmental inversion and the combined one——are presented. Numerical experimentsshow that this method is quite successful in improving the accuracy of retrieved aerosolsize distribution in both smaller part (r<1μm) and larger part (r>1μm) of aerosolsize ranges.     

EFFECT OF CRYOGENIC AND HEATING TREATMENT ON THE SOLUTION PROPERTIES OF NITROCELLULOSE

The effect of cryogenic and heating treatment on the solution properties of rigid polymer nitrocellulose (NC) in dilute tetrahydrofuran solution were studied with a sealed viscometer and a size exclusion chromatograph (SEC),respectively. The experimental results show that the relative viscosity of NC solution decreases after repeated freezing-thawing treatment. The decreased viscosity value of NC could not be restored but decreased further after the solution being re-heated. The experimental results of SEC are fully consistent with that of viscosity measurements. It is believed that the effect of two treatments on NC solution both causes the apparent hydrodynamic volume to decrease. But they are assumed to be ascribed to different mechanisms.     

EXTENDED GABOR FUNCTION MODEL AND SIMULATION OF SOME CHARACTERISTIC CURVES OF RECEPTIVE FIELD

In this paper we propose a family of extended Gabor functions as weight functions of the primary information processing in the visual system. The orientation tuning curve, the length tuning curve and spatial frequency tuning characteristics of simple cells, complex cells and some hypercomplex cells were simulated by means of our model. The results calculated by this model coincide closely with the experimental data. It has been shown that the extended Gabor function model can reasonably describe the main properties of receptive fields several levels of the visual system.     

MONTE CARLO SIMULATION OF THE SURFACE REDOXMECHANISM OF WATER GAS SHIFT REACTION 2. KINETICS OF FORWARD WATER GAS SHIFT REACTION

IntroductionThewatergasshift(WGS)reaction,duetoitsimportanceinbothhydrogenproductionandenergytechnology,hasbeenwidelyinvestigated.Inourpreviousworkll],aMonteCarlomodelwasdevelopedtoinvestigatetheconversionofOH*toO*inthesuifaceredoxmechamsmofWGSreaction,an…     

MONTE CARLO SIMULATION OF THE SURFACE REDOXMECHANISM OF WATER GAS SHIFT REACTION Ⅰ. CONVERSION OF ADSORBED OH TO OXYGEN ADATOM

IntroductionThewatergasshift(WGS)reaction,duetoitsimportanceinbothhydrogenproductionandenergytechnology,hasbeenwidelyinvestigatedHowever,therearecofltroversiesabouttheWGSreaction.echanismll--8].Inthesurfaceredoxmechanism,itisconsideredthatHZOisdissociated…     

RADIAL DISTRIBUTION FUNCTION (RDF) STUDY OF THE NONCRYSTALLINE STRUCTURE OF POLY P-PHENYLENE SULFIDE (PPS)

Owing to the existence of sulfur, a heavy atom, in the structure unit of PPS (C_6H_4S), P(r), the experimental reduced radial distribution function of its atomic-electronic density shows a group of finger print peaks in the range of 4—7 distinctly. According to the erystal structure model of PPS, an approximate P(r) curve is set up. Comparing it with the experimental results, we have discovered that the height of the 5th, 6th and 7th peak, which decreases with the decrease of sample erystallinity, is consistent with the damage of three interchain S—S distances (5.16 , 5.61, 6.76 ) in the erystal structure. And, correspondingly, the number of S—C distance is increased, which is consistent with the increase of the 4th and 7th peak height in the sample of noncrystalline state. The present authors hold that this is caused by the molecular chain displacement occurring along the direction of fibrous axis. The position of the 6th peak moving from 5.7 to 6.0 is referred obviously to the lateral space expansi     

PREPARATION AND CHARACTERIZATION OF PVDF-HFP MICROPOROUS MEMBRANE BY TEMPLATE METHOD

Porous poly（vinylidene fluoride-co-hexafluoropropylene） （PVDF-HFP） membranes were successfully prepared using dibutyl phthalate （DBP）, polyvinylpyrrolidone （PVP-K30）, polyethylene glycol 200 （PEG200） as templates. SEM was used to examine the morphology of the PVDF-HFP porous membranes. It was found that these membranes have an asymmetric structure and the blends of PVDF-HFP/DBP formed nanoporous membranes, whereas the blends of PVDF- HFP/PVP-K30 formed ＂sponge-like＂ and microporous membranes. Moreover, the average pore size and porosity was about 0.3 μm and 48.7%, respectively. The crystallinity, thermal stability and mechanical strength of membranes were characterized by XRD, DSC, TGA and stress-strain tests. The results showed that the membranes are a crystals with excellent thermal stability. It was an effective way to regulate pore size and morphology of the PVDF-HFP membranes.     

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.     

SYNTHESIS AND CATALYTIC PROPERTIES OF LAYERED DOUBLE HYDROXIDES PILLARED BY HETEROPOLYOXOMETALATE

ＳＹＮＴＨＥＳＩＳＡＮＤＣＡＴＡＬＹＴＩＣＰＲＯＰＥＲＴＩＥＳＯＦＬＡＹＥＲＥＤＤＯＵＢＬＥＨＹＤＲＯＸＩＤＥＳＰＩＬＬＡＲＥＤＢＹＨＥＴＥＲＯＰＯＬＹＯＸＯＭＥＴＡＬＡＴＥ￥ＺｈｅｎｇＸＵ；ＨｅＭｉｎｇＨＥ；ＤｏｎｇＭｅｉＺＨＯＵ；ＬｉｎｇＳｈｅｎ...     

PREPARATION AND PROPERTIES OF EPOXY RESIN MODIFIED BY LIQUID CHLOROPRENE-HYDROXYETHYLMETHACRYLATE COPOLYMER

The epoxy resin modified by liquid chloroprene-hydroxyethylmethacrylate copolymer (CP-HEMA) is a new kind of structural adhesives with good mechanical properties. By changing its mole-cular structure, it may also have such desirable properties as retardation of combustion, enduringweather aging, inert oils and chemicals. A series of the thermosets of the epoxy resin modifiedby CP-HEMA used as a toughener were prepared. The effects of CP-HEMA content, catalyst con-tent and curing temperature on the mechanical properties of modified epoxy resin system were studied.The thermal weight-loss curves were examined. The two-phase morphology was observed and dis-cussed.     

A THEORETICAL STUDY OF THE THERMODYNAMIC AND KINETIC PROPERTIES FOR THE REACTION OF FORMYL CYANIDE DECOMPOSITION

We compute the thermodynamic and the kinetic properties for the reaction:HCOCN→HCH+CO using the statistical theory and the transition-state theory.The equi-librium constants and the rate coefficients of this reaction are also reported here,andthe half lives of formyl cyanide at different temperatures are first estimated in thiswork.     

TARNISH AND PROTECTION OF SILVER DEPOSIT——MECHANISM AND METHOD

The mechanism of tarnish caused by exposure to light and Na_2S solution treatment on silver-electroplated deposit and the antitarnish effects of various antitarnish agents have been investigated in this paper. The results showed that 1-phenyl-5-mercaptotetrazole (PMTA) has excellent antitarnish effect for UV light and H_2S tests.The studies of XPS and AES and UV absorption spectra showed that PMTA can absorb effectively UV light and form a dense surface film which can prevent effectively the reactions between silver deposit with corrosive media.Antitarnish surface film could be composed of a polynuclear coordination polymeric compound with structure unit approximate to [Ag_3(PMTA)]. according to the depth dependence of percent component (C%) and sputtering time.     

METHOD OF INTEGRATED GREEN''''S FUNCTION FOR THE CALCULATION OF TILT LOAD TIDE CAUSED BY THE OCEANIC TIDES

The method of integrated Green's function for the calculation of the tilt(?)load tide proposed by this paper is sn improvement and s development of the current widely used method proposed by Farrell, and it is s new method of calculation. According to this method, the integrated Green's function of tilt load tide has been calculated first, then on the basis of the cotidal charts the tilt load tide caused by the oceanic tides at any point on the continent can be easily calculated through algebraic procedures. As an example of application of this method the tilt load tides of M_2 have been calculated on the basis of cotidal charts of Schwiderski for the following three stations: Wuchang, Tai'an and Xuzhou.