脉冲色谱法研究醇和水在疏水多孔硅胶上的吸附行为

采用脉冲色谱法测定了140℃时疏水多孔硅胶(HPS)上C2～5醇的吸附等温线及醇和水的Henry常数。分析得出,C2～5醇的吸附等温线在醇分压小于2.5kPa时符合Freundlich模型,醇分压小于0.3kPa时符合Langmuir单分子层模型,C2～5直链醇的Henry常数随醇的沸点和碳原子数的增加呈指数性递增,支链醇与HPS表面的作用力更强;醇的Henry常数可以分解为—CH3,—CH2—,—OH基团贡献值的加和,其对数值分别为0.68,0.60,0.46,-11.42;在气相条件下,因HPS的疏水性而使水分子不易接近HPS表面;HPS对醇-醇物系的分离是由于HPS具有基团选择性的特性。     

A Model for the Hybridization Exothermic Effect in Label-Free Biodetections by a Nanomechanical Cantilever-DNA Chip

The influence of the hybridization exothermic effect on nanomechanical deflections of DNA chips in label-free biodetections is investigated. First, from the related experimental curves, the thermal variation of the biolayer during the linkage of DNA base pairs is estimated by Breslauer’s method and the Langmuir adsorption isotherm. Second, the temperature field of the chip is obtained by the lumped parameter model and the classical Fourier’s method. Third, the nanomechanical deflection of the chip is predicted by an alternative model for thermoelastic problems of laminated cantilever beams. The effect of a DNA base sequence on thermal deflection of chips is also investigated. In the case of adiabatic conditions, numerical results show that the theoretical predicted value of 1.5 nm to 2 nm deflection is within the scope of the optical-beam-deflection readout system’s accuracy.     

Adsorption layer and foam film properties of mixed solutions containing β-casein and C12DMPO

The interrelations between adsorption layer properties and surface forces in thin foam films of protein/surfactant mixtures were investigated. The adsorption from β-casein/dodecyl dimethyl phosphine oxide (C₁₂DMPO) mixed solutions was studied by Profile Analysis Tensiometry (PAT). The adsorption of protein/surfactant mixtures at the air/water interface is of competitive nature. The obtained adsorption isotherms suggest a gradual displacement of the protein molecules from the interface with increasing surfactant concentration. Foam films were studied by microinterferometry, originally introduced by Scheludko and Exerowa. The obtained experimental results show that the composition of the mixed adsorption layers changes with increasing amount of added surfactant. At a certain mixing ratio the corresponding foam film thickness decreases dramatically. This change happens above the surfactant concentration where the surface tension of the protein–surfactant mixtures approaches the values obtained for the respective pure surfactant solutions. The thickness, refractive index and adsorbed amount of the respective adsorption layers were determined by ellipsometry. These results correlate with the above-mentioned PAT and foam film data. The refractive index and adsorbed amount decrease monotonically and reach values close to those for pure surfactant solutions. On the contrary, a continuous increase can be observed in the layer thickness up to the above-mentioned concentration, indicating the formation of a more diffuse layer at the air–water interface formed by β-casein and C₁₂DMPO molecules upon increase of surfactant concentration. For foam films the electrolyte concentration can change the equilibrium thickness of the films and the Π(h)-isotherms significantly.     

Moisture Uptake Behavior,Antibacterial Property,and Heat of Sorption of Nano Silver-Loaded Calcium Alginate Films

This work describes preparation, characterization, and a moisture uptake study of silver nanoparticle-loaded calcium alginate films. The equilibrium uptake data was interpreted by various isotherm models. In the lower moisture content range of 0.02 to 0.06, the enthalpy of sorption (ΔH) and differential entropy (ΔS) were 25.25 to 4.82 kJ/mol and 0.07521 to 0.01371 kJ/mol/K, respectively. There was fair correlation between ΔH and ΔS values. Finally, the higher value of isokinetic temperature, T_B (i.e., 336.77), as compared to the harmonic mean temperature, T_m (i.e., 302.05), indicated that moisture uptake mechanism was enthalpy driven.     

Structure and Electrochemical Properties of A2B7-Type La-Mg-Ni Hydrogen Storage Alloys

~~Structure and Electrochemical Properties of A_2B_7-Type La-Mg-Ni Hydrogen Storage Alloys     

Water vapor adsorption properties of amorphous cefditoren pivoxil evaluated by adsorption isotherms and microcalorimetry

Water vapor adsorption of ground cefditoren pivoxil was studied. The amount of water adsorbed increased with a decrease in the crystallinity of cefditoren pivoxil. It was found from the microcalorimetric measurements that the differential heat of water vapor adsorption at 1.5% adsorbed water increased with decreasing crystallinity of cefditoren pivoxil, suggesting that hygroscopicity of cefditoren pivoxil was enhanced by grinding. These results indicated that hydrophilic adsorption sites in cefditoren pivoxil increased through the grinding process. The results of infrared (IR) spectra examination suggested that the increment of hydrophilic adsorption sites through the grinding process resulted from the change of the environment of the carbonyl groups in two esters and amide.     

咪唑啉对碳钢在弱酸性H2S溶液中的缓蚀作用

应用计算机控制的电位扫描法研究了油溶性咪唑啉类慢剂对碳钢在弱性性Ｈ２Ｓ水溶液中的缓蚀作用,并采用三参数拟合方法对阴阳极极化曲线进行拟合计算。     

Study of the influence of some organics as thiourea derivatives and butindiol in steel pickling baths

The corrosion inhibition effect of the following organic additives: 2‐butin‐1,4‐diol (BD), N,N′‐dimethylthiourea (DMTU), N,N′‐diethylthiourea (DETU) and N,N′‐diisopropylthiourea (DITU), in steel pickling baths (sulphuric acid solutions) was studied by means of weight loss and electrochemical measurements like open circuit potential (OCP), polarization curves and impedance spectroscopy (EIS). A significant decrease in the corrosion rate was observed in presence of the investigated compounds depending on the nature and the concentration of the additives. The weight loss experiments show an inhibitory efficiency that reaches values beyond 98 %. The protective effect increases with the enlargement of the lateral chain size in the case of the thioureas. The electrochemical experiments show also a protective effect of the organic additives against corrosion. Their adsorptive behaviour is found to follow the Langmuir model.     

Adsorption of disperse dye by powdered activated carbon

The purpose of this laboratory study is to investigate the effectiveness of powered activated carbon (PAC) on the removal of chemical oxygen demand (COD) and color of disperse dye and the effect of PAC particle size on the treatment efficiency. The adsorption isotherm parameters for the Langmuir, Freundlich and BET model are determined using the adsorption data. It has been found that the multilayer BET isotherm yields significantly better fit to the observed data than the monolayer ones. A simplified mass transfer model is proposed in the present work also for estimating the external mass transfer coefficient using the initial adsorption data at low PAC dosage.     

Pore structure of new composite adsorbent SiO<Subscript>2</Subscript>·<Emphasis Type="Italic">x</Emphasis>H<Subscript>2</Subscript>O· <Emphasis Type="Italic">y</Emphasis>CaCl<Subscript>2</Subscript> with high uptake of water from air

A new composite adsorbent SiO₂·xH₂O·yCaCl₂ which is composed of macro-porous silica gel and calcium chloride is introduced. In order to analyze its adsorption theory, adsorption and desorption isotherms, BET surface areas, pore volumes and average pore diameters of macro-porous silica gel and four composite adsorbent samples with different CaCl₂ content are measured using SEM and Asap2010 apparatus. From the adsorption isotherms, desorption isotherms and lag loops, it can be deduced that the main pore structure in macro-porous silica gel and the new composite adsorbent have two shapes: taper with one top open and taper or hyperbolic taper with both ends open. Based on the analysis of pore diameter distribution and lag loop, a sketch map showing calcium chloride filled in pore of macro-porous silica gel is presented. The adsorption isotherms at 25°C are measured. Experimental results show that the new composite adsorbent can adsorb more water than common adsorbents (macro-porous silica gel, micro-porous silica gel and synthetic zeolite 13X). In the light of the results of pore structure, adsorption isotherms and lyolysis phenomenon are analyzed.