Calorimetric Determination of Enthalpy of Formation of Natural Gas Hydrates

This paper reports the measurements of enthalpies of natural gas hydrates in typical natural gas mixture containing methane, ethane, propane and iso-butane at pressure in the vicinity of 2000 kPa (300 psi) and 6900 kPa(1000psi). The measurements were made in a multi-cell differential scanning calorimeter using modified high pressure cells. The enthalpy of water and the enthalpy of dissociation of the gas hydrate were determined from the calorimeter response during slow temperature scanning at constant pressure. The amount of gas released from the dissociation of hydrate was determined from the pumped volume of the high pressure pump. The occupation ratio (mole ratio) of the water to gas and the enthalpy of hydrate formation are subject to uncertainty of 1.5%.The results show that the enthalpy of hydrate formation and the occupation ratio are essentially independent of pressure.

Characters of the P_(CO)_2 and CO_2 Flux in the East China Sea in Autumn

P CO 2 of air and seawater samples from the East China Sea (ECS) were measured in situ in autumn, 1994. Ocean currents, terrestrial fluviation, biological activities, etc.,P CO 2 characters in air and seawater were investigated. CO 2 flux and its character in the East China Sea are discussed on the basis of theP CO 2 profiles of air and seawater. It was clear that the nearshore was the source of CO 2; and that the outer sea area was the sink of CO 2; and that the shelf area of the ECS is a net sink for atmospheric CO 2 in autumn.

Extraction of Metal(Ti,V,Mo)-oxyl Cations by Monoacidic Phosphates and Phosphonates

The extraction of TiO2+, VO2+, VO2+ and NoO22+ by HDEHP, HEHEHP and HDTMPP was studied respectively. The orders of extraction ability for the three extractant systems are as follows: for TiO2+, VO2+: HDEHP>HEHEHP>HDTMPP; and for VO2+, MoO22+: HDEHP<HEHEHP<HDTMPP. The experimental results were discussed from the point of view of extractant structures.

CORRECTION FOR HOUSNER’S EQUATION OF BENDING VIBRATION OF A PIPE LINE CONTAINING FLOWING FLUID

This paper points out that Housner's equation of bending vibration of a pipe line containing flowing fluid is approximate and makes correction to it. An exact form of the vibration equation is given.

A New Voltammetric Enzyme Immunoassay System for the Detection of Alkaline Phosphatase

A new voltammetric enzyme immunoassay system was investigated based on p-nitrophenyl phosphate (PNPP) as the substrate for alkaline phosphatase (ALP). PNPP is enzymatically hydrolyzed and the product p-nitrophenol (PNP) is detected by differential pulse voltammetry (DPV), which can be oxidized at +1.02 V (vs. Ag/AgCl) on bare glass carbon electrode (GCE). The conditions for enzymatic reaction and electrochemical detection were studied. According to this method, ALP can be detected with a detection limit of 2.8102 mU/L and a linear range of 4.0102 ~ 1.0106 mU/L.

PREDICTION OF THE RHEOLOGICAL PROPERTIES OF STAR—TYPE BRANCHED POLYMER SOLUTIONS BY MEANS OF THE FIXED SPECTRUM MODEL

The Rouse-Zimm model with slippage was improved and the basic parameters of modelwere modified to explain the rheological properties of star-type branched polymersolutions. The theoretical results show good agreement with experimental data.

CALORIMETRIC STUDIES ON THE STRUCTURE OF MICROEMULSION WITH NONIONIC SURFACTANT

Enthalpic studies on the state of water in hex-adecane/hexanol/ AEO8/water system have been conducted. The results show that water exists in three states such as bound water,trap water and free water. The enthalpic effect of condition that water to oil ratio is in the abnormal rheology region, the negative thixotropy of the system is directly proportional to the enthalpy.

METHOD OF PROFILE REFINEMENT OF X-RAY AND ANALYSIS OF STRESS ON MATERIALS

Ⅰ. INTRODUCTIONIt is clear from the analysis of product failure and the quality management that the failure of machine parts is induced by the following factors: stress, environment and time. The force factor is the stress applied on the material. X-ray stress detection technology has been developed quickly during the recent decade.

PAIR-POTENTIAL STUDY OF ADSORPTION AND DIFFUSION FOR Li/Li(100)SYSTEM

The interaction between atoms, molecules and solid surface is an important research topic in the field of heterogeneous catalysis, gas erosion, separation and crystal growth. Theoretical study on a molecular level can not only help people understand the interaction mech-

A SELF-ADJUST GROWTH OF CLUSTER——RESEARCH ON CLUSTER GROWTH MORPHOLOGY

Ⅰ. INTRODUCTIONAn extensive investigation has been conducted on cluster growth in experiment and theoretical simulation since 1980. In particular, the mutual advancement between theory and experiment results in the deep understanding of cluster growth morphology and its kinetics.

Investigation of voltammetric enzyme-linked immunoassay based on new system of ODA-H_2O_2-HRP

A voltammetric enzyme-linked immunoassay based on a new system of ODA-H2O2-HRP has first been developed and used in the detection of HRP and labelled HRP. By this method, the enzyme-catalyzing reaction of H2O2 oxidizing odianisidine (ODA) couples the electrode-reduction reaction of the oxidizing product of odianisidine, which produces a sensitive polarographic wave at potential of -0.56V (SCE) in Britton-Robinson buffer solution. In using this polarographic wave, a detection limit to HRP is 3.7×10-12g/mL and a linear range 1.0×10-11-2.0×10-9g/mL. And the mechanisms of the coupling reaction and the process of electro-reduction in the ODA-H2O2-HRP voltammetric enzyme-linked immunoassay system have also been carefully studied.

Monte Carlo simulation for the micellar behavior of amphiphilic comb-like copolymers

Micellar behaviors in 2D and 3D lattice models for amphiphilic comb-like copolymers in water phase and in water/oil mixtures were simulated. A dynamical algorithm together with chain reptation movements was used in the simulation. Three-dimension displaying program was pro-grammed and free energy was estimated by Monte Carlo technigue. The results demonstrate that reduced interaction energy influences morphological structures of micelle and emulsion stems greatly; 3D simulation showing can display more direct images of morphological structures; the amphiphilic comb-like polymers with a hydrophobic main chain and hydrophilic side chains have lower energy in water than in oil.

THEORETICAL STUDY OF REACTION DYNAMICS OF H_(2)■H+H ON LITHIUM(100)SURFACE

A generalized LEPS potential energy surface of （H2?H +H）/Li（100） plane systemwas constructed based on the ab initio SCF absorption and surface diffusion of a hydrogenatom on lithium（100） surface, and reaction kinetic behaviour of this system was investigatedby means of QCT method. It was shown from analysis of the feature of this potential energysurface that the activation energy of absorption of H2 molecules on a lithium（100） planeis unnecessary and the dissociation of H2 on the Li（100） plane relates closely to the adsorp-tion sites and adsorption fashions, and the horizontal manner of dissociation of H2 is easierthan the standing one. And it was also shown from the analysis of various collision trajec-tories that the surface recombination probabilities of bi-hydrogen atoms at low covering arevery small, and that the surface dissociation probabilities of H2 are controlled by its vibra-tional quantum number. The potential energy surface of gas-metal surface interaction systemconstructed here is

An improved ELISA for the determination of southern bean mosaic virus with linear sweep voltammetry detection based on new system of PAP-H_2O_2-HRP

An improved enzyme-linked immunosorbent assay (ELISA) for the determination of southern bean mosaic virus (SBMV) with linear sweep voltammetry based on a new system of p-aminophenol (PAP)-H2O2-horseradish peroxidase (HRP) has firstly been developed. The enzymatic product 3-[(4-hydrox-yphenyl) amino]-4-(2-amino-5-hydroxyphenyl)-6-[ (4-hydrox-yphenyl)imino]-2,4-cyclohexadiene-l-one, produced from the oxidation of PAP with H2O2 catalyzed by HRP, yielded a sensitive linear sweep voltammetric response at - 0.45 V ( vs. SCE) in Britton-Robinson (BR) buffer solution. Based on the voltammetric peak, HRP can be measured with a detection limit of 0.4 mU/L and a linear range of 1.0-1.0 × 102 mU/ L. The detection limit for the SBMV is 8.0 ng/mL and the highest dilution ratio for the detection of infected leaf sap is 1: 1.5×105.

Kinetic behaviour of aluminum naphthenate/benzene system in process of gelation and degradation

The kinetic behaviour of aluminum naphthenate/benzene system in the process of gela- tion and degradation wag systematically studied. The results obtained from the kinetic experiments indicated that the gelation stage was in accordance with a. kinetic model of an auto-catalytic first-order reaction, and the degradation stage was a simple first-order reaction. The rate constants in these two stages at various temperaturs were measured. And the determined apparent activation energies for the gelation stage and for the degradation stage are 27.5±2.0 and 37.7±2.3 kJ/mol, respectively.

Nanometer metal particle catalyst with rare earth thin shell and stored hydrogen

Nanocrystalline transition metal particles were prepared by the H2+Ar arc plasma method. A lot of hydrogen was stored in nano transition metal particles. The stored hydrogen in the interstitial positions will be suddenly released in large amount at 400℃ or so. This kind of bulk hydrogen made nano-transition metal particles possess good catalysis properties. The structure of polyhydro particles was analysed using HRTEM and the energy spectrum method. It was found that a great quantity of defects exist on the surface of particles as shown in fig. 1. The surface area and reaction activity were increased. Also