Comparative study on sorption of individual and coupling cesium and selenium on mudrock

This study focused on sorption mechanism of Cs and Se in mudrock by batch techniques. Batch kinetics tests have been conducted with carriers 10^{− 4}M CsCl and SeO₂ by using individual and coupling radiotracers of ¹³⁷Cs and ⁷⁵Se. The distribution coefficients (K _d ) of Cs in synthetic groundwater (GW) and seawater (SW) showed that there is no interference between individual and coupling value (13 and 6 ml/g). Moreover, individual and coupling K _d ) (80 and 40 ml/g) of Se in GW and SW are in agreement with Cs. It is quite clear that the sorption mechanisms of Cs and Se on mudrock are independent and different by using radiotracer’s technique.     

Studies on the Adsorption and Dissociation of Methane and Carbon Dioxide on Nickel

The adsorption and dissociation of methane and carbon dioxide for reforming on nickel catalysts were extensively investigated by TPSR, TPD, XPS and pulse reaction methods. These studies showed that the decomposition of methane results in the formation of at least three kinds of surface carbon species on supported nickel catalysts. Carbidic Cα, carbonaceous Cβ and carbidic clusters Cγ surface carbon species formed by the decomposition of methane demonstrated different surface mobility, thermal stability and reactivity. Carbidic Cα is a very active and important intermediate in carbon dioxide reforming with methane, and the carbidic clusters Cγ species might be the precursor of surface carbon deposition. The partially dehydrogenated Cβ species can react with H2 or CO2 to form CH4 or CO. On the other hand, it was proven that CO2 can be weakly adsorbed on supported nickel catalysts, and only one kind of CO2 adsorption state is formed. The interaction mechanism between the species dissociated from CH4 and CO2 during reforming was then hypothesized.     

谷胱甘肽和Ebselen对胰岛素硝化的抑制及其相互作用机理的研究

生物体内NO和超氧阴离子快速反应生成的过氧亚硝酸根离子(ONOO^-，peroxynitrite)是一种强细胞毒性物质，它诱导蛋白质酪氨酸残基硝化是其损伤生物系统的重要途径之一。为了探讨谷胱甘肽和ebselen对胰岛素硝化的抑制及其相互作用机理，采用UV-Vis、HPLC和ESI-MS等方法，研究了ONOO^-对胰岛素的硝化作用、小分子抗氧化剂谷胱甘肽(GSH)和ebselen对ONOO^-硝化胰岛素的影响以及它们之间的相互作用。结果表明单独的GSH和ebselen对ONOO^--引发的胰岛素硝化均有明显的抑制，而作为谷胱甘肽过氧化物酶(GPx)的底物GSH 与GPx的模型化合物ebselen之间存在相互拮抗作用，经过对其产物分析，确定其机理是GSH和ebselen能够直接反应生成一种加合物，从而抑制了GSH和ebselen各自的抗硝化能力。     

Langmuir aggregation of Evans blue on cetyltrimethylammonium bromide and on proteins and its application

The microphase adsorption-spectral correction (MPASC) technique is described and applied to the study of the interactions of Evans blue (EB) with cetyltrimethylammonium bromide (CTAB) and with four proteins: bovine serum albumin (BSA), myoglobin (Mb), hemoglobin (Hb) and ovalbumin (OVA). EB can be adsorbed on a cationic surfactant and on protein by electrostatic force and the aggregation obeys the Langmuir isotherm. Results have shown that the products are formed as follows: monomer aggregate EB·CTAB, micellar aggregate (EB·CTAB)₇₈ and protein aggregates (EB₆₈·BSA), (EB₁₄·OVA), (EB₁₂₆·Mb) and (EB₅₈·Hb). The adsorption constant of the aggregates are calculated to be K_EB·CTAB=2.95×10⁶, K_EB68·BSA=3.40×10⁴, K_EB14·OVA=5.20×10², K_EB126·Mb=6.81×10² and K_EB58·Hb=5.73×10², respectively. The aggregation of EB in proteins is sensitive in the presence of CTAB and selective in the presence of EDTA and it has been applied to the analysis of samples with satisfactory results.     

Influence of platinum and hydrogen on n-butane isomerization on H-Mordenite

Hydrogen inhibits n-butane isomerization of H-MOR and improves catalyst stability and selectivity. Similarly, when Pt is present, hydrogen inhibits the reaction which is always controlled by the acid function.     

Effect of molecule-substrate interaction on thin-film structures and molecular orientation of pentacene on silver and gold

Evaporated pentacene thin films with thicknesses from several nm to 150 nm on gold and silver substrates have been studied by ultraviolet photoelectron spectroscopy (UPS), near-edge X-ray absorption fine structure (NEXAFS), scanning tunneling microscopy (STM), and atomic force microscopy (AFM). It was found that pentacene thin-film structures, particularly their molecular orientations, are strongly influenced by the metal substrates. UPS measurements revealed a distinct change in the valence band structures of pentacene on Au compared to those on Ag, which is attributed to the different packing between adjacent molecules. Using NEXAFS, we observed 74+/-5 degrees and 46+/-5 degrees molecular tilt angles on Ag and Au, respectively, for all measured thicknesses. We propose that pentacene molecules stand up on the surface and form the "thin-film phase" structure on Ag. On Au, pentacene films grow in domains with molecules either lying flat or standing up on the substrate. Such a mixture of two crystalline phases leads to an average tilt angle of 46 degrees for the whole film and the change in valence band structures. STM and distance-voltage (z-V) spectroscopy studies confirm the existence of two crystalline phases on Au with different conducting properties. z-V spectra on the low conducting phase clearly indicate its nature as "thin-film phase".     

粉煤灰理化性质及改土增产效应研究

研究了粉煤灰的理化性质及改土增产效应。结果表明，粉煤灰颗粒以物理性砂粒为主，含有Ｓｉ、Ｆｅ、Ｐ、Ｋ、Ｃａ、Ｍｇ、Ｚｎ、Ｃｕ、Ｍｏ、Ｂ等作物营养元素；施用粉煤灰能提高土壤物理性砂粒含量，增加土壤孔隙度，降低容量，对粘重土壤具有良好的改土效应。     

Studies on the Adsorption and Dissociation of Methane and Carbon Dioxide on Nickel Catalysts

The adsorption and dissociation of methane and carbon dioxide for reforming on nickel catalysts were extensively investigated by TPSR, TPD, XPS and pulse reaction methods. These studies showed that the decomposition of methane results in the formation of at least three kinds of surface carbon species on supported nickel catalysts. Carbidic Cα, carbonaceous Cβ and carbidic clusters C-γ surface carbon species formed by the decomposition of methane demonstrated different surface mobility, thermal stability and reactivity. Carbidic Cα is a very active and important intermediate in carbon dioxide reforming with methane, and the carbidic clusters Cγ species might be the precursor of surface carbon deposition. The partially dehydrogenated Cβ species can react with H2 or CO2 to form CH4 or CO. On the other hand, it was proven that CO2 can be weakly adsorbed on supported nickel catalysts, and only one kind of CO2 adsorption state is formed. The interaction mechanism between the species dissociated from CH4     

Note on ordering and complexity of Platonic and Archimedean polyhedra based on solid angles

The missing values for the solid angles of the two snub semiregular polyhedra have been calculated, and integrated into the whole series of Platonic and Archimedean polyhedra. This is the only criterion which so far gives an unambiguous answer (without any degeneracy leading to posets) on how to order these polyhedra according to their increasing complexity.     

Effect of Charge and Hydrophobicity on Adsorption of Modified Starches on Polyester

Polyester fabric (poly(ethylene terephthalate)) is a hydrophobic polymer. Its hydrophobic nature can be a disadvantage for certain applications like dyeing, finishing, detergency, etc. Physical or chemical modification of the polyester to make it more hydrophilic is therefore desirable for certain performance characteristics. Surface modification of polyester to make it hydrophilic can be achieved by adsorbing polymers on the polyester surface. Starch is a commonly available, hydrophilic polymer used in many textile applications that can be used to modify polyester. However, it needs to be chemically modified so that it can adsorb on the polyester fabric and physically modify the fabric characteristics. The polymers used in this study are two different modified starches—cationic and anionic starches and mixtures of the two. The adsorption kinetics on a polyester substrate was studied. The effect of charge and hydrophobicity on adsorption was investigated. Cationic starches were shown to readily adsorb on polyester and this was attributed to electrostatic interactions. Hydrophobic substituents on the cationic moiety resulted in increased adsorption. This was attributed to the weak hydrophobic interaction between the polymer chains which could result in a more coiled polymer conformation. It is hypothesized that more starch molecules are required for surface coverage of the polyester, resulting in an increase in adsorption. Anionic starch was adsorbed on the substrate but at a slower rate than the cationic starches. It is likely that there is a H bonding between acid groups on the starch and the ester groups of the polyester. However, the anionic starch is desorbed when the polyester is placed in an aqueous medium. When a blend of cationic starch and anionic starch was used, a low concentration of anionic starch was seen to increase adsorption, indicating that the polyelectrolyte complex itself may be adsorbing on the substrate. Further increases cause a decrease in adsorption as no sites may be available on the complex for adsorption. When hydrophobic substituents are present, addition of the anionic starch causes a decrease in adsorption at all concentrations. This was attributed to the “crosslinking” between the hydrophobically modified starch and the anionic polymer.     

压力和温度对水型相图平衡影响的探讨

重点从热力学原理的角度探讨压力和温度对水型相图平衡的影响,并通过计算解释了水型相图中固液平衡线上随压力升高,熔点下降的原因。     

QSPR Studies on lgK_(ow) and lgK_(oc) of Fluorobenzenes and Property Parameters Based on HF and DFT Calculations

1 INTRODUCTION Quantitative structure-activity relationship (QSAR) equation could be employed to predict the biological activities of unknown compounds, which is signifi- cant for initial screening and evaluation of toxic compounds[1]. Soil sorption coeff…     

Effect of anions and pH on the adsorption and oxidation of methanol on a platinum electrode

The influence of various anions and pH on methanol oxidation as well as its products of chemisorption on platinum has been studied by voltammetric and radiometric methods. It was found that the rate of methanol oxidation from the bulk solution was lowest for Na₂CO₃ and highest for NaOH solutions. The influence of anions on the chemisorbed species of methanol on a platinum electrode has also been investigated.     

Effect of preadsorbed water on the adsorption of p-xylene and m-xylene mixtures on BaX and BaY zeolites

Adsorption of an equimolar p-xylene/m-xylene mixture on partially hydrated barium-exchanged X and Y zeolites is studied at 423 K in the pressure range 10(-2)-8 hPa by differential calorimetry coupled with manometry and chromatography. Results are consistent with structural studies and Monte Carlo simulations of the literature. The presence of preadsorbed water in supercages increases the adsorption selectivity toward p-xylene to the detriment of the adsorption capacity and the adsorption affinity, as indicated by a sharp decrease of the Henry constants. However, the coadsorption heats at zero filling are not influenced by the presence of water. Therefore, entropic effects seem to play an important role in the coadsorption process. Two adsorption sites whose energy differs are identified by calorimetry. The more energetic site could correspond to the p-xylene or m-xylene molecule in interaction with the compensation cation located in sites II in the supercage, the less energetic to the adsorption of p-xylene molecule in the 12-ring window joining two supercages. The presence of this second site for p-xylene could be at the origin of the selectivity.     

States of Adsorbed Hydrogen and Their Effect on the Reaction of CO Oxidation on Pd and Ta

Various states of hydrogen are identified on the foil and film surfaces of palladium and tantalum by photoelectric, conductivity, and thermal desorption methods. They are formed in the course of ₂ diffusion through a membrane and in the course of adsorption from the gas phase. The effect of an ethylene pyrolysis product, pyrocarbon, on the activity in CO oxidation on the palladium surface with and without _ads is determined. The presence of hydrogen is found to weaken the effect of pyrocarbon. A study of hydrogen adsorption on the tantalum foil showed that hydrogen adsorption drastically declines in the presence of chemisorbed CO, but the H–Ta binding strength doubles. The fact that the sorption ability of tantalum is completely restored upon CO adsorption and partially restored upon ₂ chemisorption is achieved by thermochemical treatment in hydrogen.     

Viscodensitometer Studies on Gelatine and the Sorption of Gelatine on Glass

The sorption of polymers on glass surfaces, and the effects produced thereby on measurements of intrinsic viscosity, hitherto studied in capillary viscometers, is here analyzed by the sensitive viscodensitometric technique, based on the principle of the moving-sphere viscometer. By working with several spheres of equal size, the errors in viscometry due to sorption can be practically eliminated. The use of two spheres differing in radius by a factor of 10 allows the direct weighing of the polymer sorbed per unit geometric surface. In this way the sorption isotherm of an alkali-bone gelatin on Pyrex glass from 0.17 M KCl solution was found to rise to a plateau of 3 mg/m² at a gelatin concentration of 0.1 g/dl. The plateau extends from this lower limit to 0.5 g/dl. The partial specific volume of gelatin, directly obtained in the viscodensitometer along with the viscosity, was found to be 0.702 cc/g in water and 0.725 cc/g in 0.95 M KCl.     

微电极研究: 吡咯在微电极上的聚合及膜的生长过程

研究NaNo3介质中吡咯在Pt微电极(r=10μm)上的聚合及聚吡咯膜的生长过程。利用微电极的快速传质特性证实了在聚合物生长过程中有可溶性低聚物中间体形成。研究表明聚吡咯膜的生长不仅是吡咯单体氧化偶联在聚合物的链端使链增长, 而且更主要的是溶液中低聚物的连续沉积形成新的聚合中心, 随后在Pt微电极上低聚物发生沉积而形成聚吡咯膜。     

Contact angle of polyethylene on copper and its effect on adhesion

To determine whether the large differences in adhesion for polyethylene coatings applied to different types of copper surface could be attributed to changes in work of adhesion or wettability, the variations of contact angle with time has been measured for molten polyethylene droplets on these surfaces. It is concluded from these measurements that the low peel strengths obtained on certain substrates cannot be accounted for by a low work of adhesion of poor wetting of the surface.