CALCULATION OF THE YOUNG''''S MODULUS OF AN ADSORBED POLYMER LAYER

Polymer layers adsorbed to a surface or in a confined environment often change their mechanical properties. There is even the possibility of solidification of the confined layer. To judge the stiffness of such a layer, we used the Hertz model to calculate the Young's modulus of the polymer layer in the confinement of AFM experiments with silicon nitride tip with a radius of curvature of R≈50 nm and a glass sphere attached to the cantilever R = 5μm. Since there is no visible indentation of the layer in the AFM experiments, the layer is either penetrated very easily, or the indentation is too small to be seen in a force curve. The latter would be the case for a polymer layer with a Young's modulus above 4×108 Pa in case of an experiment with a silicon nitride tip and 4×105 Pa in case of a glass sphere.     

SEGMENT DENSITY PROFILES OF COMPACT POLYMER CHAINS CONFINED BETWEEN TWO PARALLEL PLANE WALLS

We use the pruned-enriched Rosenbluth method to investigate systematically the segment density profiles of compact polymer chains confined between two parallel plane walls.The non-adsorption case of adsorption interaction energyε=0 and the weak adsorption case ofε=-1 are considered for the compact polymer chains with different chain lengths N and different separation distances between two walls D.Several special entropy effects on the confined compact polymer chains,such as a damped oscillation in the segment density profile for the large separation distance D,are observed and discussed for different separation distances D in the non-adsorption case.In the weak adsorption case,investigations on the segment density profiles indicate that the competition between the entropy and adsorption effects results in an obvious depletion layer.Moreover,the scaling laws of the damped oscillation period T_d and the depletion layer width L_d are obtained for the confined compact chains.Most of these results are obtained for the first time so far as we know,which are expected to understand the properties of the confined compact polymer chains more completely.     

CRYSTALLIZATION OF BLENDS OF AN ASYMMETRIC POLY（OXYETHYLENE）-b-POLY（OXYBUTYLENE） BLOCK COPOLYMER WITH POLY（OXYBUTYLENE）

An oxyethylene/oxybutylene block copolymer with asymmetric volume fraction (E115B103) was blended with oxybutylene homopolymer (Bh) at different volume fractions of the block (φE). Crystallization behavior of the blends was studied and was compared with that of the blends from a symmetric block copolymer (E114B56). It was found that the crystallization temperature of E115B103/B28 blend is lower than that of the blends from symmetric block copolymer. For the blend with φE= 0.30 breakout crystallization with an Avrami exponent n ≈ 3.0 is observed. At φE = 0.22 the blend exhibits a variable crystallization behavior: confined crystallization with n ≈ 1.0 at lower crystallization temperatures but breakout crystallization at high crystallization temperatures. For the blend with φE = 0.14 and sphere morphology confined crystallization occurs at all crystallization temperatures studied. When compared with the blends from symmetric block copolymer, confined crystallization occurs more easily in the E115B103/B28 blends. The SAXS results agree with the isothermal crystallization kinetics. Deformation of the confined crystalline block is observed in the blend with φE = 0.14 and mixed lamellar and cylinder morphologies in the blend with φE = 0.22.     

TRANSLOCATION IN CASE OF ELLIPSOID

An extension of Bjerhammar's translocation to the involvement of the 1st order of contribu-tion of the flattening of an ellipsoid has been developed to be in keeping with a special pur-pose of higher accuracies. To complete it, we follow this way: (i) to carry out a new Poisson in-tegral involving the effect of the flattening, (ii) to solve the so-called simple Robin problemfor an ellipsoid on a boundary condition of radial derivative, and (iii) to derive a solution ofgeneral Robin problem in the case of an ellipsoid via the solution of simple Robin problem aftertransforming boundary conditions from normal derivative into radial derivative. Finally, the useof the combination of the solution of general Robin problem with the generalized Poisson inte-gral with respect to the regular harmonic function r△g on the linearized Molodensky problemfor an ellipsoid makes a definition of the desired translocation in the case of an ellipsoid. Ob-viously, this developed translocation will go back to the traditional     

STRUCTURE AND TECTONIC EVOLUTION OF OKINAWA TROUGH

Okinawa Trough is a back-arc basin with some features of transitional structures-thinned crust,active tectonic movement and high value of heat flow. Seismic survey reveals that there are three strati graphic series of different environments: layer A of Pleistocene-Holocene is thin in the north and thick in the south, layer B of the Pliocene is thin in the south and thick in the north, and layer C is an "acoustic basement". The phase Ⅰof Trough movement taking place during the last Miocene to the early pliocene is a foundational episode of tectogenesis in Okinawa Trough. The phase Ⅱin the last Pliocene is the unified and spreading episode of tectogenesis. The formation of Okinawa Trough underwent the doming phase due to upwelling of material from deep earth, the rifting phase of lithosphere, and the spreading phase from overflowing of magma and pushing both sides of rocks.     

A STUDY ON NUMERICAL SIMULATION OF CLOUD MERGERS AND INTERACTIONS

A two-dimensional, time-dependent and warm cumulus cloud model has been used to investigate problems concerning cloud merger and interaction. The results of numerical experiment show: (ⅰ) Two clouds formed at the same time have influence on each other at a shorter distance;on one hand, it is possible that they merge with equal intensity, and on the other, it is impossible that they merge with unequal intensity;in case of quite different intensities the weak cloud is depressed and the strong cloud accretes. (ⅱ) Two clouds, developing with timing difference at a shorter distance and in the same growth stages, may merge. (ⅲ) The merged cloud develops more violently than the unmerged and produces more rainfall. (ⅳ) Cloud merger results from the action of a horizontal pressure gradient accompanied with a circulation field in the lower layer of clouds.     

INFLUENCE OF SAMPLE THICKNESS ON ISOTHERMAL CRYSTALLIZATION KINETICS OF POLYMERS IN A CONFINED VOLUME

Isothermal crystallization process of polymers in a confined volume was simulated in the case of instantaneous nucleation by use of the Monte Carlo method. The influence of sample thickness on some kinetic parameters of crystallization was quantitatively evaluated. It was found that there was a critical thickness value. Influence of thickness on the crystallization behavior was only found for samples of thickness near and less than the critical value. For thick samples the Avrami plot showed straight lines with a turning point at the late stage of crystallization due to the secondary crystallization. When the thickness was near or less than the critical value a primary turning point appeared in the Avrami plot at the very beginning of the crystallization process. A model was proposed to explain the mechanism of this phenomenon. According to this model the critical thickness value is related to the nucleation density or the average distance between adjacent nuclei, and the primary turning point is an indication of a transformation of crystal growth geometry from a three-dimensional mode to a two-dimensional one. Analysis of experimental results of PEO isothermally crystallized at 53.5℃ was consistent with the proposed model.     

SOLITARY INTERNAL GRAVITY INERTIAL WAVE IN A STRATIFIED ATMOSPHERE AND NONLINEAR PROCESSES FOR THE FORMATION OF SQUALL LINES

In this paper the KdV equation is derived from the three dimensional primitive equations for a class of finite amplitude waves in a stratified basic flow. The solitary wave solution is given for a simple case where a constant and uniformly stratified basic flow is confined in a region bounded by solid walls with rectangular cross section. The properties of the solitary wave solution can give a possible explanation for the preferential occurrence of a squall line or storm cell train at the left side of a low level jet and the concurrent fluctuation in the low level jet. For more general cases, i. e. sheared basic flow and nonuniform stratification, the qualitative response of the wave amplitude to the symmetric baroclinic stability of the basic flow is analysed. The results indicate that the vertical circulation in a solitary wave will possibly be dramatically intensified in a local area where the stability is weak or negative.     

Conformational statistics of polymer chain terminally attached to wall (I)——NRW model tail chain

The simplest form of a polymer chain adsorbed on a solid surface is that the polymer chain has only one end group attached to the surface, i.e. the polymer chain forms the "tail" conformation. In the present work, the problem was simplified as the random walk confined in the half-infinite space and studied systematically. The conformational distribution functions of the model tail chain in different dimensions were obtained. It has been found that the ratio of the conformational number of the model tail chains to that of the free chains varies as a power function N-12 when the chain length N→∞. It has also been proved that for the tail chain the component of the mean square end-to-end distance in the normal direction of the confined boundary is doubled and the other components are constant in comparison with the case of the free chain.     

Investigation of the anodic decomposition of the solid electrolyte RbCu4Cl3I2

The process of electrochemical decomposition of the solid electrolyte RbCu₄Cl₃I₂ at a vitreous carbon electrode has been investigated. The anodic decomposition of the electrolyte occurs in two steps. At first, the oxidizing electrode reaction of Cu⁺ ions to Cu²⁺ ions takes place at potentials higher than 0.57 V and a layer of decomposition products is formed on the electrode surface, including the divalent copper compound RbCuCl₃. Then the oxidizing reaction of I^– ions occurs at potentials higher than approximately 0.67 V, with deposition of an iodine layer onto the electrode surface. The deposition rate of the layers of decomposition products is controlled by instantaneous nucleation and two-dimensional growth of the deposit. The total thickness of the passivating layer of decomposition products on the anode is equal to ca. 1 μm. Electronic Publication     

REINFORCEMENT OF POLYDIMETHYLSILOXANE NETWORKS BY NANOCALCIUM CARBONATE

Although a number of investigations have been devoted to the analysis of silica or carbon black filled elastomer networks, little work has been done on the reinforcement of CaCO3 filled elastomer network. In this work, the reinforcement of polydimethylsiloxane (PDMS) network by using CaCO3 nano-particles was investigated. We have found a simultaneous increase of tensile strength, modulus and elongation with the increase in nano-CaCO3 content, which suggests that nano-CaCO3 particles can indeed be used as a reinforcing agent, just like silica or carbon black. Interestingly, the tensile strength,modulus and elongation were seen to leave off for the first time when the content of nano-CaCO3 particles reaches to 80%.PDMS also showed an enhanced elastic modulus and storage modulus with the increase in nano-CaCO3 content, particularly for samples with high nano-CaCO3 content. SEM was used to investigate the dispersion of the filler in PDMS matrix. A better dispersion was found for samples with high nano-CaCO3 content. A great increase of viscosity was found for samples with higher filler content, which is considered to be the reason for the good dispersion thus the reinforcement, because high viscosity will be helpful for breaking the agglomerates of fillers into small size particles under effect of shear. Our work provides a new way for the reinforcement of elastomer by using an adequate amount of nano-CaCO3 particles instead of as mall quantity of silica, which is not only economically cheap but also very effective.     

THE STUDY OF ADAPTABILITY OF Drepanopus bispinosus TO TEMPERATURE AND SALINITY IN THE ANTARCTIC BURTON LAKE

The tolerance to temperautre and salinity of a Calanoida copepod: Drepanopus bispinosus from the Burton Lake in the Vestfold Hills, Antarctica, was tested in each season. The results obtained show that the copepod has a marked physiological property of tolerance to low temperature and high salinity, and this property could be strengthened after winter. The response to different temperature and salinity of the copepod evidently expressed the tardy characteristics contrasted with seasons. This means that for a long term in early winter(lower temperature and higher salinity) the animal still has higher tolerance to lower salinity and higher temperature; and it is opposite in early summer. These physiological features are possibly caused by natural acclimatization in the lake. The experimental data were processed and plotted by computer. The correlation of animal's survival rate with the changes of temperature and salinity presented an approximately smooth surface of a three-degree elliptic sphere.     

Kinetics of oxidation of butene-1 to butanone in aqueous solution in the presence of ions Pd2+ and Mo-V-phosphoric heteropoly acid

Oxidation of butene-1 to butanone in the presence of homogeneous catalysts (PdSO₄ + HPA-x), where HPA-x = H_3+xPV_xMo_12-xO₄₀, 1 ￡ x ￡ 4, was investigated. This reaction is found to be of the 1st order with respect to C₄H₈, and of the 0.64th order with respect to Pd. The reaction rate does not depend on the HPA-x concentration and pH of the solution. The activation energy of the reaction is variable. A kinetic expression of the reaction is obtained for 303-343 K. This revised version was published online in June 2006 with corrections to the Cover Date.     

MOLECULAR VOLUMES OF SALTS. WITH TRIANGULAR RADICALS

The present paper discusses some characteristics of the molecular volumes of carbonates, nitrates and borates. It confirms that the molecular volume of H_2O in the hydrates of this kind of salts approximates to a constant. When the coordination numbers of cations in mixed salts are identical with those in the single salts, the additivity of the molecular volume is quite accurate. Over 100 sets of data demonstrate that a general additivity is true, the average relative error being ±2.31%. The concept of the topological molecular volume is proposed based, on the additivity. For salts with the same radical and equally charged cations, the molecular volume varies linearly with the cation radius. The volume effects of CO_3~(2-) NO_3~- and BO_3~(3-) in packing can be obtained by extrapolation. They are equal to a large sphere whose volume is the sum of those of three O~(2-). This paper also discusses the possibility of compiling a table of ionic volumes.     

EFFECT OF DISPERSION OF MICA IN MATRIX ON YOUNG''''S MODULUS OF MICA FILLED POLYETHYLENE

The correlation between Young's modulus of mica-filled high density polyethylene (HDPE), low density polyethylene(LDPE) and the state of dispersion of plasma-treated mica in the polymer matrices was studied. The modulus and the number average diameter of mica aggregates in matrix were determined with tensile testing and image analysis respectively. The interface structure of the filler/matrix and the bulk structure of matrix were examined through the dielectric spectrometry, differential scanning calorimetry (DSC) and dynamic viscoelastic spectrometry. The results show that the Young's modulus of the filial polyethylene depends to a great extent upon the state of dispersion of filler in matrix, but it is independent of the interface structure and bulk structure. The better the dispersion, the higher the Young's modulus.     

DROUGHT-EARTHQUAKE RELATION AND MEDIUM-RANGE PREDICTION OF GREAT EARTHQUAKES

In order to approach the medium-range prediction of great earthquakes with Ms≥6, the author investigated the relation between drought and earthquakes and believed that the drought-earthquake relation is an effective method for the medinm-range prediction of great earthquakes.When the author studied the meteorological effects on the earthquake preparation, he found that the epiecntral regions of great earthquakes with M≥6 are usually dry for one to three and a half years before earthquakes. The draught area changes with the earthquake magnitude proportionally. If an earthquake occurs in the 3rd year of drought, its magnitude is 0.5 higher than that in the 1st year of the drought.According to the above-mentioned facts, the author puts forth the medium-range prediction method and principle of great earthquakes by the drought-earthquake relation: (ⅰ) the magnitude is defined in accordnce with the area of the drought regious; (ⅱ) the possible risk area is defined on the basis of the location of the droug     

ULTRASTRUCTURE OF THE NUCLEOLUS AND REPLICATION SITES OF RIBOSOMAL DNA IN Allium cepa

Our conventional EM observations indicate that the nucleolus of Allium cepa is composedof the fibrillar centre (FC), fibrillar component (F) and granular region (G). FC is an elec-tron-lucid zone which contains condensed or loosened chromatin. F is a circular, highly elec-tron-dense component which surrounds FC and consists of compact fibrils. EM autoradiographic(EM ARG) studies with ~3H- UdR reveal that the synthesis of ribosomal RNA (rRNA) takesplace in F. G is situated around F and composed of granules about 25 to 30 nm in diameter.EM ARG studies with ~3H- TdR demonstrate that silver grains are predominantly located in Gof the nucleolar periphery and the region of the nucleolus-associated chromatin. In addition,~3H- TdR labels are also present, but with a much lower frequency, in FC. F and G of the nu-cleolar interior. According to the distribution and sphere of silver grains in different compo-nents of the nucleolus, we suggest that the replication sites of ribosomal DNA (rDNA) aremainly located in     

IN-SITU AFM OF POLYMER CRYSTALLIZATION

Atomic force microscopy images taken during the crystallization of polyethylene both from processed andquiescent melts are presented. Crystallization from processed melts provides further evidence of a region in front of agrowing lamella that is influenced by the crystallization process, but extending only 40 nm into the melt. High-resolutionimages of the growing crystal tip, taken during crystallization, show no direct evidence of the existence of intermediatephases. The growing tip is shown to be slightly rounded. In-filling crystallization, occurring after the initial flush of growth,is imaged in polyethylene for the first time, and shown to continue to a temperature 8℃ below the initial crystallizationtemperature.     

STUDIES ON SEDIMENTATION RATE OF CONTINENTAL SLOPE OF THE SOUTH CHINA SEA

Sedimentation rate of sediments on the continental slope of the South China Sea has been determined by the Th_(ex)~(230) method. Results show that in the upper part of the core from the surface layer down to 48 cm there might have occurred a downslope, reflecting a discontinuous depositional process and palaeoclimate becoming warmer; in the middle section of the core the activities of Th_(ex)~(230) show an exponential decrease with increasing depths and depoaitional rate is 1.6mm/1000 years, and sediments might have been formed in a cold and deep-water environment: in the core from 90cm downward there might have been an active sedimentary environment with a warmer palaeoclimate.Based on the contents of U and Th, U/Th ratios and their relationships with Fe, Mn, Corg and P in all layers of the core, it is inferred that materials of the studied waters are mainly of terrestrial phase with a portion of authigenous constituents.