Dynamic Study of Gemini Surfactant and Single-chain Surfactant at Air／Water Interface

Molecular dynamics (MD) simulation are used to study the properties of gemini surfactant of ethyl-α,ω-bis(dodecyldimethylammonium bromide) (C12C2C12) and dodecyl-trimethylammonium bromide (DTAB) at the air/water interface, respectively. In the two systems,t he surfactant concentrations are both 28 wt.%, and other conditions are also the same. After reaching the thermodynamic equilibrium, the concentration profiles, the radial distributions functions (RDF) and the mean squared displacement (MSD) are investigated. The results reveal that the surface activity of C12C2C12 surfactant is higher than DTAB surfactant.     

Optimum gas chromatographic conditions in wall-coated capillary columns. Extended and simplified forms of the Golay-equation

Band broadening in capillary columns is satisfactorily described by the Golay-equation extended to situations of appreciable pressure drop by Giddings. In practice, however, several simplifications are often made. The effect of these simplifications on the calculated values of the minimum plate height and optimum carrier gas velocity are treated systematically.     

毛细管电色谱中双电层叠加的研究

通过流动相中电解质浓度对毛细管电色谱柱效能的流动相平均线速度的影响，研究了ＣＥＣ中双电层叠加现象。提出选择合适电解质组成的浓度及在制备色谱柱过程中避免细小和破碎的固定相颗粒进入柱中，以有效地减小双电层叠加作用。     

冷态德士古气化炉流场与停留时间分布的研究

测定了德士古气化炉的冷态速度分布和停留时间分布。结果表明：德士古气化炉内在轴向２．５～３．０倍直径范围内存在回流，最大回流量为射流量的３．５倍左右；在平均停留时间之前，已有５０％左右的物料逸出炉外。本文指出，德士古气化炉中存在的问题，如结渣、耐火砖寿命短、有效气体成分偏低均与炉内流场有关。     

层流中粉尘的火焰传播速度

建立了筛落式粉尘火焰试验装置和火焰信的号光电测量系统。提出确定火焰前沿位置的“最大斜率切线法”和判定火焰传播稳定性的“相对入射能量法”。测定了硅钙粉和煤粉的火焰传播速度和火焰厚度。结果表明数据合理,测量装置和方法可用于速度范围很宽的粉尘火焰传播研究,用修正的田中达夫模型计算的硅钙粉层流火焰传播速度与实验值接近。     

Binding studies of sodium dodecyl benzene sulphonate with poly(N-vinyl-2-pyrrolidone)

The binding of sodium dodecyl benzene sulphonate (SDBS) with poly(N-vinyl-2-pyrrolidone) (PVP) has been investigated at 303.15 and 313.15 K using equilibrium dialysis, surface tension, viscosity, ultrasound velocity and ultrasound absorption techniques. From each of these studies four distinct regions of SDBS-PVP interactions were observed. Interaction of SDBS with PVP was found to involve the binding of surfactant dimers with the polymer molecule followed by usual micellization. The binding data has been analyzed in terms of various models of polymer-surfactant interaction.     

Influence of biomass on hydrodynamics of an internal loop airlift reactor

The effect of the biomass presence on the overall circulation velocity, the linear velocities both in the riser and the downcomer and the overall gas hold-up was studied in a three-phase internal loop airlift reactor (ILALR). The measured data were compared with those obtained using a two-phase system (air—water). All experiments were carried out in a 40 dm³ ILALR at six different biomass concentrations (ranging from 0 g dm⁻³ to 7.5 g dm⁻³), at a temperature of 30°C, under atmospheric pressure. Air and water were used as the gas and liquid model media, respectively. Pellets of Aspergillus niger produced during the fermentation of glucose to gluconic acid in the ILALR were considered solid phase. In addition, liquid velocities were measured during the fermentation of glucose to gluconic acid using Aspergillus niger. All measurements were performed in a bubble circulation regime. At given experimental conditions the effect of the biomass on the circulation velocities in the ILALR was negligible. However, increasing of the biomass concentration led to lower values of the total gas hold-up. Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May 2006.     

Sound velocity in different reacting thermal plasma systems

In most cases the energy dissipated in plasma jets used either,for heating or spraying is varied by changing the are current, the total gas floc+rate, and composition. However, when doing so, conditions are reached where the plasma jet may become supersonic. To predict such conditions or to characterize supersonic plasma jets the knowledge of the sound velocitya is mandatory The goal of this paper is to calculatea versus plasma forming gas composition, temperature, and pressure. Rigorous calculation would imply the knowledge of the chemical reaction kinetics, sound velocity depending strongly on this. Unfortunately such kinetics are generally lolknown for plasma jet floras and the only possibility is to determine the equilibrium sound velocitya calculated through the isentropic coefficient T. This coefficient has been calculated taking into account the dissociation and ionization reactions at equilibrium for temperatures ranging from 300 to 25,000 K and pressures between 0.1 and 1 Mpa for Ar, H₂, He, Ar-He, Ar-H₂, O₂, N₂, air, .steam, and methane.a often called the frozen sound velocity, was also calculated using (ratio of specific heats) instead of .     

Hydrogen Effect on Coke Removal and Catalytic Performance in Pre-Carburization and Methane Dehydro-Aromatization Reaction on Mo/HZSM-5

1. Introduction As an effective utilization of methane, the methane dehydro-aromatization was focused in the last decade [1-28]. Over the Mo/HZSM-5 bi- functional catalyst at high reaction temperature, methane can be converted into light aromatics (ben- zene and naphthalene) and hydrogen. Mo active species can activate the C—H bond of methane; and HZSM-5 supplies the acid sites for the oligomeriza- tion and cyclization of hydrocarbons to form aromat- ics, and suppresses the deeper condens…