Computer Simulation on Kinetics of Primary Processes in Photosynthesis Ⅰ——Mechanism of Exciton Annihilation of Excited State Decay in Phycobiliproteins

A discrete model was used for studying the effects of exciton annihilation on the decay behavior of the excited state in phycobiliprotein super-molecules. The simulation shows: The more the chromophores are and the higher the excitation beam intensity is, the more susceptible to annihilation is a system; annihilation starts to occur at 10~(13) photons/cm~2 and becomes saturated at about 10~(15)—10~(16) photons/cm~2 with the parameters used in the current work. Whether the exciton annihilation occurs or not should not be simply judged from whether the decaying data could be fitted with a mono-exponential function. The quantum yield of fluorescence decreases synchronously with the increase of exciton annihilation extent. The so called "safety intensity" has significance only in special cases. In fact, annihilation extent is dependent not only on the pulse intensity but also on the width of the pulse, the optical cross section of a chromophore as well as the light absorption coefficient of a system.     

Solubility of water in polymers—atomistic simulations

The combination of the thermodynamic-integration approach and Widom's particle-insertion method is shown to be appropriate to determine the excess chemical potential of water in dense, amorphous polymer microstructures from MD simulation at an atomistically detailed level. The two-step method is applied to bisphenol-A–polycarbonate (BPA–PC) and polyvinylalcohol (PVA). The results are compared to previously published calculations on water sorption of various polyamides and show the applicability of the two-step method for the calculation of the excess chemical potential of water in a variety of polymer materials to obtain an estimate of their water sorption behavior.     

Manganese electrochemistry—a pillar of development of electrochemistry in Georgia

Journal of Solid State Electrochemistry - The paper tells the short story of development of electrochemistry in Georgia. It demonstrates the flow of events bringing the electrochemistry of the...     

The Performance of Rhodium Complex—diphosphine Systems in the Hydroformylation of 1—Dodecene

The catalytic performances of four HRh(CO)(PPh3)3-diphosphine (BISBI,BDPX,BDNA and BINAP) systems in 1-dodecene hydroformylation were investigated and compared with HRh(CO)(PPh3)3-PPh3 system.The catalyst system HRb(CO)(PPh3)3-BISBI exhibited very hig regioselectivity for the formation of linear aldehyde.     

Application of charge transfer reaction in the pharmaceutical analysis——Determination of chlorhexidine acetate

A spectrophotometric method for the determination of chlorhexidine acetate is described. The reaction between chlorhexidine acetate and chloranil took place in an alcohol-acetone solution at room temperature. The composition of the charge transfer complex is 1:2. Beer's law is obeyed in the concentration range of 15--270 μg·mL-1 with correlation coefficient 0.9995. The apparent molar absorptivity is 2.21×103 L·mol-1·cm-1 at 412 nm. The method is accurate (with a recovery of 100±1.6%) and precise (RSD=1.0%). It was successfully applied to determine chlorhexidine acetate in suppository or disinfectant solution.     

Changes in Protein Composition in Erythrocyte Membrane of Ethanol—Poisoned Rats After Administration of Teas

Selective hydrolysis of the protein to peptides, their resolution by chromatography and determination of the amino-acid sequence in individual peptides is one method applied to studies of their modifications and mutations in pathological conditions. The purpose of this work is the determination of the green and black tea effect on peptides and their amino acid contents in integral erythrocyte membrane proteins in ethanol intoxicated rats. It was shown that ethanol intoxication causes a decrease in peptides and their amino acid contents in comparison with the control group. The ingestion of green (black) tea with ethanol partially prevents these ethanol-induced changes.     

Oligomerization of organochlorosilanes in the acetylacetone—carbamide system

Condensation of acetylacetone with carbamide in nonpolar media (benzene, toluene) is initiated by organochlorosilanes. The reaction rapidly occurs under mild conditions to give oligosiloxanes and 4,6-dimethylpyrimidin-2(1H)-one hydrochloride. The conversion of chlorosilanes and the yields of oligosiloxanes are nearly ～100%.     

Measurement and prediction of liquid—liquid equilibria of ethyl acetate—methanol—water in the presence of dissolved inorganic salts

The effect of sodium chloride, calcium chloride and zinc chloride at concentrations 5–20% by weight on the liquid—liquid equilibrium (LLE) data of the ternary system ethyl acetate(S)—methanol(C)—water(A) has been investigated experimentally at 30 °C. The region of heterogeneity is significantly increased with the addition of sodium and calcium chloride salts. A change in the direction of tie-line was observed for 10% sodium chloride, 20% calcium chloride and saturated zinc chloride exhibiting thereby a tendency to form solutropism for this system, which is non-solutropic under a no-salt condition. The selectivity values are also altered in comparison with that of a no-salt condition. The tie-line data have been correlated by the Eisen—Joffe equation. The solubility envelopes for the salt systems have been predicted using the NRTL model, from a knowledge of the binary vapor—liquid equilibria (VLE) determined experimentally in our laboratory employing the iso-activity criterion.     

Studies on Polymer Chain Dimension in Solution——Calculation of Osmotic Pressures of Polymer Solutions

A modelr which has been developed to account for the effects of concentration on the chain dimensions of dissolved polymers has been combined with Zimm's statistical mechanical relation for the virial coefficients of dilute suspensions of hard spheres. The osmotic pressures (π/c) of 16 types of polymer/solvent calculated are in quite good accordance with experimental results from dilute to semi-dilute solutions and even concentrated solutions.In this procedure no adjustable parameters are needed except for the number average molecular weight of the sample and its intrinsic viscosity estimated from MarkHouwink coefficients.     

The distribution of degree of crystallinity—New concept in polymer science

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Synthesis of Titanium Silicalite—1 in the Presence of Tween 40

Ｔｒａｄｉｔｉｏｎａｌｌｙ ,ｔｈｅｈｙｄｒｏｔｈｅｒｍａｌｓｙｎｔｈｅｓｉｓｏｆｔｉ ｔａｎｉｕｍｓｉｌｉｃａｌｉｔｅ 1 (ＴＳ 1 )ｎｅｅｄｓａｌａｒｇｅａｍｏｕｎｔｏｆｔｅｔｒａｐｒｏｐｙｌａｍｍｏｎｉｕｍｈｙｄｒｏｘｉｄｅ (ＴＰＡＯＨ)ａｓａｔｅｍｐｌａｔｅ ( ｎ(ＴＰＡＯＨ) ｎ(ＳｉＯ2 ) =0 4～ 1 0 ) ,ａｎｄｔｈｅｃｒｙｓｔａｌｌｉｚａｔｉｏｎｔｉｍｅｔａｋｅｓ 10～ 30ｄ[1] .Ｒｅｃｅｎｔｌｙ ,ｍｕｃｈａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎｐａｉｄｔｏｔｈｅｍｏｄｉｆｉｃａｔｉｏｎｏｆｓｙｎｔｈｅｓｉ…     

Degradation of Polylactide—Polyethylene Binary Blends in Soil

Russian Journal of Applied Chemistry - Binary polylactide-low-density polyethylene blends of various compositions were prepared, and their biodegradability in soil and water absorption kinetics at...     

Analysis of two-phase flows in gas—solids injectors

The results of the numerical analysis of the aerodynamic model of gas-solid flow in injectors for both single-size particles and a mixture are presente The theoretical pressure distributions along the axis in the respective parts of the injector (nozzle, mixing tube, diffuser and pipe section) are foun to be in agreement with the experimental data of Bohnet and Wagenknecht and the data of Hutt at the assumed values of the energy transformation coefficients. Fitting the results to the data allowed one to find the values of angles of jet expansion in the hopper area.In the case of a mixed-size particle mixture it is found that the particle acceleration depends strongly on the inlet gas jet velocity and that the dif     

Importance of inter-residue interactions in ligand—receptor binding

In the present study, the role of inter-residue interactions in ligand binding and the ligand—receptor interactions were examined. Computational chemistry methods of ligand docking and molecular dynamics simulations were used to study the binding of β-funaltrexamine (β-FNA) and N-methyl-β-funaltrexamine (N-methyl-β-FNA) to μ- and κ-opioid receptors and to the μ-receptor with Lys303^6.58Glu mutation. It was found that inter-residue interactions Lys233^5.39—Glu303^6.58 in the mutant receptor and Lys227^5.39—Asp223^5.35 in the κ-receptor are more likely to prevent covalent bond formation between β-FNA and the receptor than the ligand-receptor interactions. This emphasizes the importance of inter-residue interactions in ligand binding as well as the effects of point-mutations.     

Formation of chitosan—surfactant complexes in aqueous-alcohol media

Russian Chemical Bulletin - The complexation of chitosan and anionic surfactant, sodium dodecyl sulfate (DDS), in aqueous-alcohol media with a variable content of an organic cosolvent (methanol,...     

The Rearrangement of 2—Benzothiazolylthioacetyl Hydrazide in Synthesis of s—Triazolo[3,4—b]benzothiazole—3—thiol

The rearrangement reaction of 2-benzothiazolylthioacetyl hydrazide 1 with potassium hydroxide and carbon disulfide in ethanol to produce s-triazolo [3,4-b] benzothiazole-3-thiol 3 was described. 3 also can be obtained from 2-benzothiazolylhydazine 2 and the two methods for getting 3 were compared. Mannich reaction of compounds 3 was reported too.