Study on the Electro—reduction of Perfluorodecalin

The reduction of perfluorodecalin was studied by the method of electrochemistry.The results indicated that the electrochemical reduction of perfluorodecalin was a multi-step reaction. The mechanism of the first consecutive reaction showed that it is to diffusion controlling step.     

ab Initio Calculation on Tautomerism of Pyrazolin—5—ones

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Studies on Agarofurans Ⅷ.Synthesis of the Metabolites of 4—Butyl—α—agarofuran

The structures of five metabolites (2-6) of agarofuran 1 were confirmed by synthesis. The configuration of the secondary hydroxyl in 7 was determined by Horeau′s method. The configuration of C-2 in compound 4 and 5 was determined by their stereochemistry and NMR.     

Micro—patterning of Copper Based on Photolithographed Self—assembly Monolayers

A new method has been develoed for fabrication of copper micro-pattern by selective chemical copper deposition based on photolithographed (3-mercaptopropyl)-trimethoxysilane (MPTS) self-assembly monolayers (SAMs). As confirmed by scanning electron microscopy (SEM), Cu closely replicated the mask features. The present approach makes this technic to be cheap and may be applicable to assembly of microelectronic circuits.     

902 — Effect of Ca2+ on electrobioluminescence of Lampito mauritii

The nature of the electrolyte in the medium has been observed to produce a pronounced effect on the light output of the electronically generated bioluminescence of the earthworm Lampito Mauritii. Of the several ions investigated in the study, Ca²⁺ doubles the bioluminescence output, others, such as Fe²⁺, Fe³⁺ or Mg²⁺, etc., reduce the bioluminescence intensity. The mechanism of this enhancement is discussed with a proposal that the uptake of Ca²⁺ by the earthworm electrode results in an excessive displacement of coelomic cells.     

Effect of pH on the Rheology of Al-Mg Mixed Metal Hydroxide——Montmorilonite Aqueous Suspension

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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 action of lipophilic UV absorbers — solubilized by cyclodextrin — on photofading of aqueous solution of azoreactive dyes

Two representatives of water-insoluble UV absorbers ( 3-(4-methylbenzilidene)camphor and 2-hydroxy-4-methoxybenzophenon ), different in their chemical structure, could be solubilized by two pairs of studied CDs (BCD, GCD, RAMEB, AcGCD). The substituted CD entities were markedly more effective solubilizers than the unsubstituted ones. The rate of photofading of an aqueous azoreactive dye solution was significantly increased in the presence of the substituted CDs. Mixing UV absorbers, solubilized by the mentioned CDs, to the aqueous dye solution marked deceleration in photofading could be achieved.     

Quantitative Structure—Property Relationship on Prediction of Surface Tension of Nonionic Surfactants

When a surfactant is solved into a solvent, it will adsorb onto the surface of the solution and reduce the surface free energy to a marked degree. The surface free energy, which is the minimum amount of work required to create that surface, is usually measured by surface tension. The minimum of surface tension 0g is the most useful key for characterizing the activity of surfactant. It is well known that 0g is determined by the molecular structure of surfactant, i.e., the contributions from …     

Adsorption of mercury species on river sediments — effects of selected abiotic parameters

Abiotic parameters (pH, temperature, current velocity, mercury species concentration, and sediment and aqueous media composition) influence mercury species (MeHg⁺, EtHg⁺, PhHg⁺ and inorganic Hg²⁺) adsorption on river sediments. The highest amount of adsorbed MeHg⁺ and EtHg⁺ (82–93% and 85–91% for static and agitated system, respectively) occurred at pH 3–4. For PhHg⁺ the maximum adsorption (90% and 95% for static and agitated systems) was located over the broad 3–10 pH range, while for Hg²⁺ (94% and 97% for static and agitated systems) it was at pH ∼ 3. Temperature (4.5–60°C) influenced the adsorption rate but not the quantity. Both rate and quantity increased in the order: static < agitated ≤ stirred systems. The aqueous medium composition affected both rate and quantity. Sulfate caused the largest adsorption decrease for organomercury species (15–25% decrease); sulfide reduced Hg²⁺ adsorption about 67%. Cations at pH 5.2 reduced either the adsorption rate (Ca²⁺, Al³⁺) or the total adsorption (Zn²⁺, Fe³⁺). Positive correlations were found between sediment C, N, S content as well as cation exchange capacity (CEC) with mercury adsorption (R = 0.45–0.66, 0.56–0.89, 0.45–0.61 and 0.55–0.73, respectively) while negative correlations were observed with Fe and Al (R = −0.63 to −0.90 and −0.65 to −0.86, respectively).     

Effect of concentration on surfactant micelle shapes——A molecular dynamics study

Above the critical micellar concentration (cmc), micelles with a wide variety of structures and shapes are formed with the increase of surfactant concentra-tion in surfactant-water or surfactant-water-oil systems, such as spherical micelles, rodlike micelles, and bilay-ers. The viewpoint that micelle should be in spheres of constant size was first proposed by Hartley[1]. Later experiments by light scatter indicated that most mi-celles were indeed spherical, and their aggregation numbers were c…     

Theoretical Investigation on Radical—Coupling Reactivity of Indolinonic Aminoxyls

Indolinonic aminoxyls can effectively scavenge various radicals by directly coupling with them or by initatin superoxide dismutase.To better understand the radical-coupling reactions,DFT method B3LYP/6-31G(d,p) was employed to calculate variations of free energy for the coupling reactions and other physico-chemical parameters.The radical-coupling activity difference between aminoxyls was elucidated to a large extent in terms of elctronic properties of substituents.     

The Adsorption of Aqueous—Organic Mixture Components on Cellulose

The isotherms of composition changes were obtained for the cellulose—water—dimethylsulfoxide and cellulose—water—acetonitrile systems. The isotherms of sorption of aqueous—organic mixture components on cellulose were calculated. The heat effects of wetting of cellulose with water—dimethylsulfoxide and water — acetonitrile solutions were measured. The special features of sorption of the components on cellulose were shown to be related to the character of cluster formation in the binary systems under consideration.     

Capacitance Characterization of the Effect of pH Value on the Self—assembled Monolayers of Octadecanethiol

In this paper,the membrane capacitance(Cm),which was obtained from the ecectrochemical impedance spectroscopy(EIS) method,was used to characterize the effect of pH value on the self-assembled monolayers(SAMs) of octadecanethiol(18SH) for the first time.The results not only strongly proved that inorganic ions could penetrate the SAMs of 18SH,but also ascertained that SAMs of 18SH were not an absolute of free of ion-penetration.Verifying the existence of pin-holes in the octadecanethiol SAMs was the main contribution of this paper,which coincided with the former conjecture very well.     

Theoretical Study on Reactivity of Electron Transfer in Model—System of Oxidation of α—Amino Carbon—centered Radical by O2

Electron transfer reaction between a simplified model model molecule of α－amino carbon-centered radical and O2 has studied with ab initio calculations at the MP2/6-31 G^**//UHF/6-31 G^** level,The reactant complex and the ion pair complex have been optimized and employed to perform calculation of the reaction heat and the reorganization energy,Solvent effects have been considered by applyning the conductor-like screening model,Theoretical results show that the highly endothermic charge separation process ,in which one electron transfers from the α－amino carbon-centered radical to O2,so as to form an ion pair complex,is difficult to occur in gas-phase,By apply-ing an external electronic field to prepare the charge-locallized molecular orbitals,the charge-separated state has been obtained using the initial-guess-induced self-consistent field technique,The theoretical investigations indicate that the solvent effect in the process of the oxidation of α-animo carbon-centered radical by O2 is remarkable.From the rate constant estima-tion ,it can be predicted that the oxidation of the model donor molecule by O2 can proceed,but not very fast.A peroxyl radi-cal compound has been found to be a competitive intermediate in the oxidation process.     

The effect of particle size on peak intensities of FT—IR photoacoustic spectra

The effect of particle size on peak intensities of FT—IR photoacoustic spectra was investigated by use of naturally occurring quartz in our Laboratory. It is observed that the PAS peak intensities increases with a decrease in particle diameter and that the peak intensity ratios are not constant for particles of different diameters. The relations among particle size, peak intensity and thermal diffusion length are discussed.