INSERTION REACTIONS OF CARBOETHOXYCARBENE TO ALKANES

The insertion reactions of carboethoxycarbene on n-pentane, n-hexane, n-heptane and n-octane are studied. The products of each of the reactions were separated and identified by gaschromatography-mass spectrometry. The ratio between the products inserted on various C-atoms in each reaction is not coincident with that calculated from the reaction probability.This can be explained by a suggested reaction mechanism, in which the carbonium ion or freeradical, first formed during the abstraction of H-atom by the carbene, will rearrange partial-ly before recombination with the carboethoxy-methyl anion or free radical.     

GEOCHEMISTY OF BICYCLIC ALKANES IN SEDIMENTS, COAL AND CRUDE OILS

By using GC-MS to analyze the extracts of source rocks, coal and crude oil samplesformed in different sedimentary environments in China, New Zealand and Australia, twenty-two compounds of five types of bicyclic alkanes have been dis covered in the samples. Thispaper makes an exposition of stereochemical structure, abundance and distributive features ofthese compounds and their relation to sedimentary environments and thermal evolution. Furt-thermore, it demonstrates how the abundance ratios of bicyclic alkanes to steranes and ter-panes, drimane to homodramane and the relative abundance of C_(15),C_(16),C_(12)-C_(14) series of bicyclic-alkane compounds can be used to judge and determine types of oil and gas forming environ-ments (the depositive environments of source rocks from which the oil and gas wereformed), characteristics of source rocks and degree of maturation.     

THEORETICAL ANALYSIS OF KINETICS OF NONISOTHERMAL CRYSTALLIZATION OF POLYMERS

The classical crystallization theories proposed by Avrami, Evans, and Mandelkern wereextended to the nonisothermal situation. The expressions derived from the classical equations canbe expressed in either the differential form or the integral form. A method was provided so as toobtain the parameters characterizing the crystallization rate and mechanism from DSC curves withseveral constant heating or cooling rates. The rate constants of crystallization obtained from bothisothermal and nonisothermal curves of poly(ethylene terephthalate)were compared.     

CHERTS AND GEOCHEMISTRY OF STRATABOUND URANIUM ORE DEPOSIT OF CHERT TYPE

In this paper, the characteristics of various types of cherts are described, and the clas-sification and origin of bedded cherts are discussed. The author suggests that most of thebedded cherts are generated from the accumulation of died organism, such as radiolarians,diatoms and siliceous sponge spicules, which have imbibed silica from sea water before dy-ing. Concerning the geological and geochemical features and the origin of the strata-bounduranium ore deposit of chert type, a special emphasis is put on the discussions about the for-mation of ore-source beds and the relationship between uranium deposits and crustal move-ment.     

CATALYTIC ACTIVITY OF Pd-Sn COMPLEX CARBONYLATION OF ACETYLENE

The influence of different concentration of HO, SnCl2, Cl- and n-BuOH on the carbonylation of acetylene has been studied. The results show that the yield of n- butyl propionate increases with the increase of HC1 concentration and the catalytic activity is depressed when Cl" concentration increases. However, the stability of catalytic complex is promoted by Cl-. The key to the carbonylation of acetylene lies in the addition of SnCl2, which promotes the formation of the complex of C2H2, CO with catalyst and plays an important role in the hydrogen removal from n-BuOH. The hydrogen removed from n BuOH is the hydrogen source of this reaction. Meanwhile, the principle of the effect of HCl, Cl- and SnCl2 on reaction has been discussed. The reaction model has also been proposed.     

DISCOVERY OF SPECIAL PREDOMINANCE OF VANADYL PORPHYRIN AND HIGH ABUNDANCE OF Di-DPEP IN NONMARINE STRATA

By means of TLC, UV-Vis, HPLC and MS analyses, the types, structure and fingerprint distribution of porphyrin compounds in the nonmarine strata of China have been studied herein. It is revealed that the predominance of vanadyl porphyrin in lacustrine sediments of the Ordos Basin resulted from the high maturity, while the abnormal high content of Di-DPEP in the boghead-cannel coal from Guizhou Province was probably related to its abundant source input, the weakly oxidizing condition during the early diagenesis and the consequent reducing environment.     

THE N-NITROSAMINES IN TOBACCO SMOKE AND ITS ADSORPTION AND DEGRADATION

1. INTRODUCTION Tobacco smoking ranks as a major public health problem whose negative impacts have been well established since the report of “smoking and health” published by the royal medicine academy of English in 1954. Besides nicotine, the major inducer of tobacco dependence, cigarette smoke also contains various toxic compounds, notably N-nitrosamines. Nitrosamines are formed by the nitrosation(addition of an N=O group, from the nitroso ramifications NO2, N2O3,N2O4) of secondary…     

SUBSTITUTION REACTIONS OF ALKANES——BROMINATION OF PENTANE,HEXANE AND HEPTANE

In the photo-bromination of pentane, hexane and heptane with bromine, N-bromo-diethylamine or N-bromo-succinimide, the authors found that the mono-bromo-pentanes, -hexanes and-heptanes obtained contain the isomers in the same proportions disregarding whatever brom-inating reagent is used. Among the isomers, 2-bromo-compounds occur in dominant quantitieswhile 1-bromo-compounds are nearly nil. The authors attributed these phenomena mainly tothe low mobility of bromine molecules but the rearrangement of the alkyl free radicals fromprimary to the secondary. Compared with chlorination, chlorine molecules are more mobileand combine with alkyl free radicals rather rapidly before rearrangement occurs, which makes1-chloro-isomer more abundant.     

THEORETICAL PROBLEMS OF DISCRETE GAUSSIAN ANALYSIS OF GEOMAGNETIC FIELD

Starting from the fact that Gaussian (spherical harmonic) analysis of geomagnetic field is a 'three-dimensional problem', some theoretical problems of Gaussian analysis arising from the discretization observational points are studied in this paper. Firstly, the orthogonality of discrete harmonic functions is discussed. Secondly, the basic relationship for estimating the errors of Gaussian coefficients to be determined in Gaussian analysis of discrete observational points is obtained by using perturbation method, and from this relationship the various factors influencing the errors of Gaussian coefficients to be determined and their relationship are studied. Finally, the investigation of the independence of Gaussian coefficients in discrete Gaussian analysis points out that if the distribution of observational points and the choice of weights make the orthogonality relations not satisfied, 'three-dimensional significance' of Gaussian analysis will be impaired.     

REACTION MECHANISM OF BENZOPHENONE-PHOTOINITIATED CROSSLINKING OF POLYETHYLENE

The radical intermediates, the crosslink microstructures, and the reaction mechanism of benzophenone (BP)-photoinitiated crosslinking of low-density polyethylene (LDPE) and model compounds (MD) have been reviewed in detail.The spin-trapping electron spin resonance (ESR) spectra obtained from the LDPE/BP systems with spin-trap agents showthat two kinds of polymer radical intermediates are mainly formed: tertiary carbon and secondary carbon radicals. The spin-trapping ESR studies of MD/BP systems give further evidence that photocrosslinking reactions of PE predominantly takeplace at sites of tertiary carbon, secondary carbon, and especially allylic carbon when available. The high resolution ~(13)C-NMR spectra obtained from LDPE and MD systems show that the crosslink microstructures have H- and Y-type links andthat their concentrations are of the same order. The fluorescence, ESR ~(13)C and ~1H-NMR spectra from the PE and MDsystems demonstrate that the main photoreduction product of BP(PPB) is benzpinacol formed by the recombination of twodiphenylhydroxymethyl (K·) radical intermediates. Two new PPB products: an isomer of benzpinacol with quinoid structure,1-phenylhydroxymethylene-4-diphenylhydroxymethyl-2, 5-cyclohexadiene and three kinds of α-alkyl-benzhydrols have beendetected and identified. These results provide new experimental evidence for elucidating the reaction mechanism in the BP-photoinitiated crosslinking of polyethylene.     

SKULL MORPHOLOGY OF THE TRITYLODONT GENUS BIENOTHEROIDES OF SICHUAN

Bienotheroides wanhsienensis, known as the latest, representative of the tritylodont groupis characterized by the very short snout, largely covered maxilla and wide and flat basi-parasphenoid region, as compared with the others. In this paper the evolutionary changesof the osteology and venous system of the ear region from cynodonts to tritylodonts aredescribed and the growth and replacement of the postcanine teeth and the occlusion of thisanimal are discussed.     

A STUDY ON GEOCHEMICAL CHARACTERISTICS OF CONDENSATE

This paper makes an approach to the characteristics of the compound and carbon iso-topic composition of condensate in the Sichuan, Shaanxi-Gansu-Ningxia, Dongpu and Jiyangbasins in China. The results we have obtained show that the compound properties are re-lated to the maturity. The Paraffin Index Ⅰ and the Saturated-Aromatic Index (SAI) increasegradually from the immature to mature (or over mature) condensate. and the SAI valueincrease from 2 to more than 30. The carbonisotopic composition of condensate is control-led by the type of parent matter. If the oil and condensate come from the same source rock,they will have similar carbon isotopic composition. In the same region there is an obviousdifference in carbon isotopic composition between the condensate generated from coal-bear-ing strata and that from oil-source rocks. The difference can be regarded as a parameter fordistinguishing the coal-type gas from the oil-type gas. In the same basin the carbon isotop-ic composition of the natural gas-oil-co     

EXPERIMENTAL STUDY OF INVASION AND METASTASIS OF CANCER CELLS AND ESTABLISHMENT OF THE MORPHOLOGICAL PATTERN IN THE PROCESS OF INVASION AND METASTATIC MODELS OF CANCER CELLS

For the study of invasion of tumor cells in vitro and in vivo methods were used to observe theinvasion process and morphological characteristics of tumor cells. The different animal tumor cells andcell lines from human tumors were used. The process of cancer cells in vitro invasion can be dividedinto 5 stages. We suggest that filopodia protruding from the tumor cell margin seem to play an im-portant role in the initiation of cell invasion. For experimental study of cancer metastasis we established three spontaneous metastatic models, in-cluding spontaneous lymphatic and hematogenous metastasis of mouse uterine cervix carcinoma No 14(U_(14))and No 27(U_(27)), and third spontaneous lung metastasis in mouse forestomach carcinoma (FC). Two tumorcell lines are established: One is MFC cell line which is derived from FC tumor; second cell line isMUCC which is derived from the U27 tumor. These metastasis models and their cell lines are veryuseful for studying the mechanism of metastasis, tumor heterogenicity an     

DETERMINATION OF DEGREE OF CRYSTALLINITY OF NYLON 1212 BY WIDE-ANGLE X-RAY DIFFRACTION

Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calculated and the formula of degree of crystallinity of Nylon 1212 was derived by a graphic multipeak resolution method. The degree of crystallinity calculated from the WAXD method is compatible with those obtained by density and calorimetry methods.     

STUDY OF THE MECHANISM OF LOESS COLLAPSE

In this paper, firstly, the amount of collapsible space is statistically determined from the pore-size distributions of loess slices before and after collapse by using a polarizing microscope. Then, the characteristics of the structure and the copulation of loess grains are studied, and the copulations which decrease in strength upon contact with water are discovered. Lastly, by studying the joint action of external causes——a certain load and a certain moisture content——and internal conditions, the mechanism of loess collapse is advanced.     

A STUDY OF THE EFFECT OF ANTAGONISTIC ELEMENTS OF SELENIUM WITH GRAPHICAL AND COMPUTER BASED STATISTIC PATTERN RECOGNITION

THE antagonistic effect is important in the research on bio-trace elements,the practical aspects and an understanding ofthe mechanism of which depend on a knowledge of this effect.In this paper,the data of the per-capita intake of Seand Se-antagonistic elements (Zn,Cd,Cu,Cr,Mn,As) in 27countries and areas and the age-correlated mortalities fromcancer of the breast were treated with the graphical and com-puter based statistic pattern recognition method.The 22equations derived from computer programs of linear regressionanalysis show that a multidimensional space can be reduced toa two-dimensional one.Then the two-dimensional figures wereobtained and they illustrate some empirical rules from whichinformation on the degree and area of the antagonistic effectis obtained.The calculation results of breast mortalitiescoincide with those of the U.S.female breast observed valueand the Keshan disease in China.     

INVESTIGATION OF ELECTRONIC SPECTRA OF AZOCOMPOUNDS——ABSORPTION AND EMISSION SPECTRA OF β-NAPHTHOL AZOBENZENE DERIVATIVES

Absorption and emission spectra of eight naphtholazobenzene derivatives are investigated.Absorption processes of n→π~* and π→π~* transition and emission processes from the excitedstates are studied separately in each compound. Intra- and inter-molecular energy transfersfrom the excited states of different chromophores are discussed. Effects of the molecularstructure and the pH value of the solution on the electronic spectra are discussed also. On thebasis of quantum chemistry theory, the spectral data are analyzed qualitatively.     

CALCULATION OF EPR PARAMETERS OF THE LOW-SPIN.d~5 COMPLEXES

<正> Calculation result indicates that the lowest Kramer's doublet of the low-spin d5 complexes proposed by Prof. W. C. Lin and the first order approximate matrix derived by us from the 1.s matrix table of d1 ion and the hole energy level model put forward by Prof. W. C. Lin and Taylor respectively are more suitable to the calculation of EPR parameters of the low-spin d5 complexes. The calculation conditio gzz>gyy>gxx>0 established by Taylor is used by us to obtain two parameters simultaneously, i.e, the orbital reduction factor k of a positive number near to unity, and the rhombi-city λ in range from 0 to 1/3 which is a satisfactory quantitative para meter. The same accurate EPR parameters can be obtained from both this method and Griffith's method.     

TECTONIC FRAMEWORK OF THE CONTINENTAL BASEMENT OF SOUTHEAST CHINA

The chronology and tectonic evolution model of the continental basement in southeast China margin is an important debatable geological subject. The Cathaysia is shown in this paper to be in accordance with many geological facts and also with the age data obtained by multi-dating method. Its age has been determined to range from 900 to 2000 Ma. The age of the unconformity plane in the Cathaysia is 1400 Ma. The collision and suture between the Jiangnan oldland and the Cathaysia took place during the early Jinning Period. Toward Jiangxi, Hunan, Guangdong and Guangxi, these two continents gradually opened to form a residual oceanic basin. The sedimentation centre of the basin continuously migrated southwestward from the Jinning through the Caledonian Period, and finally closed in the Guangxi Movement and Dongwu Movement. The drift-rotation of the Cathaysia after the Jinning Period has been inferred.     

DEPOLYMERIZATION AND KINETICS OF DEPOLYMERIZATION OF POLYETHYLENE TEREPHTHALATE USING DIBUTYLTIN OXIDE CATALYST

Depolymerization of poly（ethylene terephthalate） （PET） was performed in the tubular bomb microreactor which contained the solution of PET in methanol and dibutyltin oxide at the temperature ranging from 433 K to 473 K, the reaction time from 5 to 45 min and the catalyst-to-PET ratio of 0.3%-2% by weight. The optimal condition for PET depolymerization catalyzed by dibutyltin oxide is the temperature of 443-453 K, the reaction time of 20-25 min and 0.8% by weight of catalyst. By using differential methods, the activation energy for the depolymerization process was found to be 154.05 kJ/mol in the temperature range from 433-463 K.