MOLECULAR ORBITAL THEORY ON CHAIN CONJUGATE POLYMERS(Ⅲ)——THE FACTORIZATION OF EIGENEQUATION OF TWO-DIMENSIONAL CONJUGATED SYSTEMS

The factorization of eigenequation of two-dimensional conjugated systems which consistof repeated units is given with non-periodic boundary conditions in this paper, and a possibleconductive polymer is predicted.     

MOLECULAR ORBITAL THEORY ON CHAIN CONJUGATE POLYMERS——TWO TYPES OF FACTORIZED EIGENEQUATION USING LOCAL SYMMETRY FOR CHAIN CONJUGATE POLYMERS

For two types of straight chain conjugate polymers, the factorized representations of HMO eigenequa-tions have been found by using difference equation method and local symmetry. The periodic factor,angular frequency, is determined. The results obtained are described by two theorems.     

STUDIES ON THE CHAIN STRUCTURAL EFFECT OF PVDF AND VDF (52)/TrFE(48) COPOLYMER BY MEANS OF THE METHOD OF DIELECTRIC RELAXATION

Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF (95 )/VF (5), VDF (52)/TrFE (48) and VDF(47. 5)/TrFE(47. 5)/HeFP (5) over a range of-120-140℃, 10-2-10~4Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chainof PVDF led to disappearing of α-relaxation and increase in T_g (3℃) of VDF (95)/VF (5).Because of the spatial impediment of 5mol% HeFP in copolymer chain, the Curie point of VDF(52)/TrFE(48) decreased by 30℃ and T_g by 3℃. The behavior of dielectric relaxation indicatedthat 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline regionreduced, the activation energy of local relaxation increased and the relaxation time prolonged respectively.     

STUDIES ON THE TOTAL SYNTHESIS OF MAYTANSINOIDS (Ⅳ)——SYNTHESIS OF MAYTANSINE

This paper reports the total synthesis of optically pure maytansinol and maytansine. The physical constants and spectral data including R_f, m.p., specific rotation, HPLC, UV, CD, IR, NMR, and MS, of synthetic maytansinol and maytansine are identical with those of natural products in all respects. The preliminary biological test showed that synthetic maytansine possesses the same inhibitory activity in vitro against carcinoma cells as the natural product.     

THE STRUCTURE BASIS OF THE POOR FIBRIN SPECIFICITY OF UROKINASE(Ⅱ)——THE INHIBITION OF UROKINASE A CHAIN 149--157 ON THE FIBRIN STIMULATED ACTIVATION OF PLASMINOGEN BY TISSUE TYPE PLASMINOGEN ACTIVATOR

In view of the similarity of the charge distribution between fibrin A_α148--161 and Achain 149--157 of urokinase,the latter might compete with fibrin A_α148--161 when singlechain pro-urokinase is converted to double chain urokinase.To test this, the stretch of uro-kinase A chain 135--157 was separated from the low molecular weight urokinase, a competi-tive binding between this stretch and fibrin to tPA kringle-2 was shown by radio-bindingassay. The inhibition of the stretch on the fibrin stimulated activation of plasminogen wasdemonstrated in the caseinolytic system. The synthesized novapeptide urokinase A chain 149--157 (R-peptide) showed a significant inhibition on the activation of plasminogen in the pres-ence of fibrin. By contrasting finely with R-peptide, a synthesized novapeptide in which Arg154and Arg156 were replaced by Asp (D-peptide) did not show any inhibition effect on the fi-brin stimulated activation of plasminogen by tPA. These results suggest that the positivelycharged residues in the     

STUDY ON THE KINETICS OF POLYMERIZATION OF MMA BY COPPER (Ⅱ) CHELATING RESINS

The polymerization of MMA initiated by copper (Ⅱ) chelating resins/CCl4 system was studied. From the kinetic data, the kinetic equation of polymerization can be expressed asRp = Ke-56400/RT[MMA]1.57[CCl4]m[RESIN-Cu]0.18where m:3-4. 5,when [CCl4] 0. 1-6. 93M. The free radical polymerization mechanism is proposed. The primary radicals are formed by the process of complexation-chlorine transformation among the copper(Ⅱ)chelating resin,CCl4 and methacrylate.     

TERMINATION AND TRANSFER OF THE CHAIN RADICALS IN THE POLYMERIZATION OF ACRYLONITRILE INITIATED BY VANADIUM(V)-THIOUREA REDOX SYSTEM

The dependence of the molecular weights on the concentration of reactants in the polymerization of acrylonitrile initiated by vanadium (V)-thiourea redox system has been investigated. It was found that the molecular weights of the polymer change nonlinearly with increasing concentrations of nitric acid and thiourea. Probably, the composition of the complexes exert a great influence on the chain initiation and termination. The reaction of "complextermination" gives rise to the decrease of the molecular weights markedly while the concentrations of thiourea and vanadium (V)in the range from one to three molar ratios.     

LINEAR COMBINATION OF UNIT ORBITAL APPROXIMATION (Ⅱ)——A QUANTUM CHEMISTRY METHOD FOR THE POLYMERS WITH NON-PERIODIC BOUNDARY CONDITIONS

In this article we give a new quantum chemistry calculation method, and get the eigenequation using the nearest neighboring approximation, and deduce the formula for calculating the ordered polymers with terminal functional groups. Using polyene as an example, the results calculated show that the method given in this article if efficient for the quantum chemistry calculation of ordered polymers with non-perlodic boundary conditions.     

RAMAN SPECTROSCOPIC STUDY ON THE CHAIN CONFORMATION OF ELECTROSYNTHESIZED POLY(ρ-PHENYLENE)FILMS

Poly(ρ-phenylene)(PPP)films have been electrochemically deposited on mirrorlike stainless steel(SS)electrode surfaces by direct oxidation of benzene in boron trifluoride diethyl etherate(BFEE)solutions at a constant applied potential of 1.7 V(versus Ag/AgCl).The chain conformations of as-grown PPP films have been studied by Raman spectroscopy.The results demonstrated that high synthesis temperature favors the formation of planar PPP,and the conformation of planar PPP can be changed into torsional PPP by cooling treatment.     

CONFORMATION AND CHAIN PACKING STRUCTURES OF POLY (ρ-PHENYLEN BENZOBISTHIAZOLE) BY MOLECULAR SIMULATION*

The conformation, the chain packing stabilization and the unit cell modeling of poly(p-phenylene benzobisthiazole) have been investigated by using molecular simulation techniquein the present work. A coupling behaviour of σ-bond rotations at either side of the pheny-lene ring or the heterocyclic ring was found surely to exceed a length of the repeat unit ofthe polymer chain. For a single chain model, the stable torsion angle of the repeat resultedat 14°. In the crystalline cell minimization, the dihedral angle along the polymer chaincould even be stabilized in various values. It therefore indicates that the intermolecularinteraction does play a considerable role for this polymer forming the conformation. Ac-cording to cohesive energies calculated for these unit cell models, the torsion angle in themost stable crystalline cell is 0°. When the chains packing together, there exist so manyenergy stable wells along the chain axis 0.35--0.36nm apart from neighbouring chains.Most of the unit cells have quite closed cohesive energies. These factors thus cause thedifficulty of forming an unique perfect crystalline structure of the polymer. The presentstudy suggested a number of reasonable unit cells, and the most stable crystalline structurefor this polymer that is monoclinic, non-primitive unit cell.     

STUDY OF DESCENDING INHIBITORY AND FACILITORY EFFECT OF THE ORBITAL CORTEX ON THE ELECTRICAL DISCHARGES OF MEDIAL GENICULATE BODY (MGB) NEURONS IN RABBITS

Experiments were performed on 16 rabbits immobilized with flaxedil. The recording of spontaneousdischarges and the discharges of single MGB neurons caused by clicks showed that when the cerebral-orbital cortex was stimulated, of 92 MGB neurons responding to clicks, 25 units (27.2%) were inhibited,14 units (15.2%) werw facilitated, and 15 units with spontaneous discharges were completely inhibited.The topographical distribution of stimulated points with such inhibitory and facilitory effect is quite con-centrated on the orbital cortex. Stimulation of two adjacent points of the orbital cortex could respec-tively result in different kinds of inhibitory and facilitory effect on discharges of a same MGB neuron.Due to the existence of this descending effect with a short latent period (2-3 ms), the authors have reasonto believe that there might be an "orbital cortex-MGB" direct pathway. Moreover, application of 2%procaine to block the auditory cortex behind the rhinal sulcus (ACBRS) could abolish the facilitor     

ON THE POLYCONDENSATION REACTION WITH MONOMER OF A_aB_b TYPE (Ⅰ)——SOL FRACTION AND GELATION CONDITION

With monomer of A_aB_b type, the sol fraction of polycondensation for post-gel, in whichnot only the functional groups of A to react with those of B, but also the functional groupsof A with those of A and the functional groups of B with those of B are involved, is discuss-ed in detail. As a direct result, the gelation condition is obtained explicitly.     

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.     

STUDIES ON CROP LOSS CAUSED BY STRIPE RUST ON WINTER WHEAT (Ⅱ)——EFFECT OF DISEASE ON THE LEAF PHOTOSYNTHESIS

Winter wheat was used to investigate the effect of stripe rust (Puccinia striiformisWest.) on the photosynthesis of leaves with different disease severity. The rates of CO_2 uptakeof leaves were measured with an infrared gas analyzer. The results showed that on the dis-eased leaves the maximum rate of photosynthesis of the uncolonized part (P'_(max)) was negative-ly proportional to the disease severity and could be described as P'_(max)=P_(max)*(1- 0. 826*S).The photosynthsis model was built as P = I*@*P_(max)* (1 - b*S)/(P_(max)* (1- b*S) + I*@).From this model two relative photosynthesis reduction models were deduced: L_(photo) = A*S~n,where n = f(P'_(max)/P_(max)), and L_(photo) = 1 - (1 - S)*(1-b*S)*(P_(max) + I*@)/(P'_(max) + I*@).The relationship between the critical point crop loss model and these models was discussed.     

STUDIES OF CROP LOSS CAUSED BY STRIPE RUST ON WINTER WHEAT (Ⅲ)——DISEASE EFFECT ON THE SINK-SOURCE RELATIONSHIP OF HOST

Two methods, leaf-detaching and interval weighing of dry matter of different organs, were used to study the effect of stripe rust (Puccinia striiformis tritici West.) on the sink-source relationship of winter wheat Yianda 1817. The results showed that on diseased plants the absolute contribution value of each leaf arrangement was reduced; the relative contribution value of each leaf arrangement was unchanged; the contribution weights among the leaf arrangements were constant; the compensation among the leaf arrangements decreased. The results also showed that the diseased host could regulate its sink-source relationship by feedback mechanism, such as reducing the size of sink, shortening the perilod of growth, and increasing the relative translocation rate. The more serious the disease scverity, the greater the relative translocation rate and the smaller the economical index.     

THE INTRAMOLECULAR AROMATIC-RING STACKING INTERACTION OF MIXED LIGAND PALLADIUM(Ⅱ)COMPLEXES Ⅲ.STUDIES ON THE Pd~(2+)-A-UTP~(4-)SYSTEMS BY HNMR

The intramolecular aromatic-ring stacking interaction of mixed-ligand complex Pd(A)(UTP)~(2-)in the system pd~(2+)-A-UTP~(4-)has been determinedby ~1HNMR,where A=1,10-phenanthroline(phen),2,2'-bipyridyl(bpy)and DL-tryptophan(trp~-);UTP~(4-)=uridine 5-triphosphate.The result indicates that itis the partial stacking between the uracil ring of UTP~(4-)and the heterocyclicring of A that makes H(5),H(6)and H(1')in the UTP~(4-)shift upfield signifi-cantly.Accordingly,the order of aromatic-ring interaction in the mixed-ligand complex has been obtained as follows:Pd(phen)(UTP)~(2-)(?)Pd(bpy)(UTP)~(2-)Pd(trp)(UTP)~(3-).     

STUDY ON THE DETERMINATION OF TRACE BISMUTH(III) BY THIN-LAYER RESIN PHASE SPECTROPHOTOMETRY

1.INTRODUCTIONThinlayerresinphasespectrophotometryisanewanalyticalmethodinthefieldofspectrophotometricanalysis;ittakesitssourceattheliquid-liquidextractiontechniquesincombinedwithclassicalspectrophotometricanalysis.Thesubstanceofproposedmethodisaccordingtounderprinciplesthatthetargetmetalionswasassociatedwithsomeligandsinaqueousphase,thentoformedaternaryormulticomponentcomplexions,suchasanioncomplexes.Aftertheassociationreactionwasfinished,thecomplexionswillassociatedwithaion-exchangeresin…     

STUDY ON THE FORMATIONAL MECHANISM OF THE NORTHERN YELLOW (Huanghai) SEA COLD WATER MASS (Ⅱ)——DISCUSSION ON THE SOLUTION OF THE MODEL

The theoretical solution of the model of the Northern Yellow (Huanghai) Sea Cold Water Mass (NYSCWM) reveals that the NYSCWM is mainly formed through the continuous temperature increase of the overwintered water body above the Northern Yellow Sea Depression (NYSD) after spring when heat is continuously conducted from the sea surface to the'deeper layer. In the NYSCWM's growing period, (June-July), nonlinear, vertical convection and advection effects continuously increase, and are gradually balanced by the heat diffusion effect as the temperature increases from the surface to the bottom, which leads to the formation of an intensive thermocline and lateral front. Meanwhile, the three-dimensional circulation correspondingly occurs. In the NYSCWM's entire growing period, the horizontal circulation is always in the cyclonic motion, while the vertical circulation passes through a transition from a period with the cold centre as downwelling to a period with the cold centre as upwelling.     

ELECTROCARBOXYLATION OF ORGANIC COMPOUNDS WITH CARBON DIOXIDE CATALYTZED BY METALLOPORPHYRINS(Ⅳ)——EFFECT OF VARIOUS FACTORS ON ELECTROCARBOXYLATION

The effects of various factors on the electrocarboxylation of organic compounds withcarbon dioxide catalyzed by metalloporphyrin are studied.The optimal potential of electrocar-boxylation is -1.6 V(vs.SCE).A weak protic solvent methanol can enhance catalytic activity.Tetrabutylammonium iodide is the best one of five electrolytes.The yields and current efficienciesof electrocarboxylation are increased slowly as the concentration of catalyst increases.     

INVESTIGATION ON THE RELATIONSHIP BETWEEN INTRINSIC VISCOSITY AND MOLECULAR WEIGHT OF POLY (VINYL CHLORIDE-DIETHYL MALEATE)

A poly (vinyichloride-diethyl maleate) copolymer has been fractionated by repeated precipitation method. All fractions and the unfractionated sample have been characterized by viscometry, dynamic osmometry, Zimm static osmometry, light scattering and gel permeation chromatography. After correction for polydispersity, a [η]～M relationship for monodisperse polymer solutions has been obtained:[η]=1.99×10~(-3)M~(0.87) (ml/g, at 25℃, in cyclohcxanone)For the copolymer solution in THF, the second virial coefficient A_2 decreases as the molecular weight increases. The relationship isA_2=2 slope ((?)_n RT)~(-1/2).