An Approach of a Nonlinear Dynamic Model for Micellar Effects on Bimolecular Reactions.

The study of the influence of surfactant charge on alkaline hydrolysis reactions of acetylsalicylic acid (ASA) and triflusal (TFL) using spectrophotometric methods

By using a Gemini surfactant, [C 14 H 25 N + (CH 3 ) 2 -(CH 2 ) 2 -N + (CH) 3 ) 2 C 14 H 25 ]·2 Br - (C 14-2-14 ), with a short spacer group (s=2) as structure-directing agent and sodium silicate as precursor, high-quality, ordered cubic mesoporous silica with space group Pm3n was prepared by the S + l - route (S=surfactants, I=precursor). The samples were characterized by small-angle X-ray diffraction, transmission electron microscopy, and N 2 adsorption-desorption. The results showed that the pore structure of the resulting mesoporous silica belonged to the cubic system (space group Pm3n). The unit-cell parameter of the cubic system was in the range of 8.81-9.14 nm, The high-quality cubic mesoporous structure was formed at molar ratio, of C 14-2-14 to sodium silicate of 0.33:1 to 0.16:1 and a molar ratio of ethyl acetate to sodium silicate of 2:1. N 2 adsorption-desorpti curves revealed type IV isotherms and HI hysteresis loops. The primary pore volume, and the most probable pore size according to the Barrett-Joyner-Halenda (BJH) model, increased with increasing molar ratio of C 14-2-14 to sodium silicate.

Study of the Pm3n space group of cubic mesoporous silica

Polymerization kinetics of acrylamide in micelles and microemulsions

The alkaline hydrolysis of aromatic and normal aliphatic acid esters has been studied at 25°C in micellar solutions of surfactants (DTAB, TTAB, CTAB, SDS, Brij 35 and Triton X—100) with UV spectrophotometry and the method of thermokinetics in this paper. The rate constants of the alkaline hydrolysis of esters in micellar pseudophase, k1m and K2m have been calculated, respectively. The ratios of k2m to k2w or k1w to k1w indicate that the alkaline hydrolysis of esters arc inhibited by all of the surfactants investigated. It was supposed that such inhibition is mostly in relation to the micropolarity of micellar surface. The critical micellar concentrations of the corresponding systems have also been measured with the conductivity method and UV spectrophometry in this paper.

The effect of cationic, anionic, and nonionic surfactant micelles on the alkaline hydrolysis of esters

The effect of mixed micelles (polyethylene glycol-CTAB cationic surfactant, shortchain alcohol-SDS anionic surfactant) on the alkaline hydrolysis of normal aliphatic esters has been studied at 20 and 30°C with the method of difference of thermogram-area of thermokinetics in this paper. The results indicate that this reaction is inhibited by the single and mixed micelles. The mixed micelles of PEG and CTAB exhibit a greater effect of inhibition on the reaction than those do in single PEG or CTAB systems. The extent of inhibition for the reaction in the mixed micelles of SDS and alcohol is less than that in single SDS micellar solutions. The critical micellar concentrations of the corresponding systems have also been measured with the conductivity method in this paper.

The alkaline hydrolysis of ethyl acetate and ethyl propionate in single and mixed micellar solutions

The kinetics of the polymerization of acrylamide in aqueous solution and CTAB micellar solution initiated by sodium sulfite has been investigated with the theory and method of thermokinetics for n order reactions with equal concentration in this paper. The influence of initiator and CTAB concetrations on molecular weight of polyacrylamide has been discussed.The second—order rate constants of this reaction at 30 and 40°C in aqueous solution are 0. 112and 0. 0262dm3 mol-1s_1, respectively. The activation energy,based on measurements at these two temperatures,is 66. -4kJ mol-1. The ratio k2√n in CTAB micellar solution is smaller than that in aqueous solution. The rate of forming radical in micellar solution has been decreased.

Studies on thermokinetics(xvi) the kinetics of the polymerization of acrylamide in micellar solution

The alkaline hydrolysis of aspirin has been studied in CTAB micellar solution with the method of thermokinetics for the pseudo-first-order reactions in this paper. The second-order-rate constants of this reaction at 30 and 35°C in the absence of CTAB are 0. 0394 and 0. 0628 dm3 mol−1 s−1,respectively. The rates of this reaction in CTAB micellar solutions at 30 and Z5V have decreased as the increased of CTAB concentration at the considerable values of [OH−]- This reaction has been found to be inhibited by CTAB micelles.

Studies on thermokinetics(x iv) the alkaline hydrolysis of aspirin in miceliar solution

Establishment of the Characteristic Thermogram Equation of Conduction Calorimeter

Ground glass pulmonary nodules have small grayscale differences and uneven distribution of grayscale values. Traditional random walks consider only grayscale features in the definition of weights, which are not accurate enough in the calculation of weights for regions with small grayscale differences, thus leading to segmentation discrepancies. In this paper, a segmentation algorithm based on region growth and improved random walk is proposed to improve the accuracy by introducing geometric distance and Gabor texture feature values in the weight calculation. Firstly, the coarse segmentation is done by using region growth; then the connected regions of the image are judged by grayscale and geometric features to locate the lung nodule region; finally, the improved random walk is used to complete the segmentation of lung nodules. Experiments show that the proposed algorithm can effectively improve the segmentation accuracy and Dice coefficient, and reduce the RVD to a large extent. 

Chen Xiaonan

Papers

The alkaline hydrolysis of ethyl acetate and ethyl propionate in single and mixed micellar solutions

Studies on thermokinetics(xvi) the kinetics of the polymerization of acrylamide in micellar solution

Studies on thermokinetics(x iv) the alkaline hydrolysis of aspirin in miceliar solution

Establishment of the Characteristic Thermogram Equation of Conduction Calorimeter

GGN segmentation based on region growing and improved random walk