Surface modification of γ-Al2O3 by sodium ions

¹H/²³Na double resonance NMR techniques were employed to study the modification of surface hydroxyls on γ-Al₂O₃ by sodium ions. ¹H→²³Na cross polarization (CP) experiment can resolve three kinds of sodium cations that are closely associated with surface hydroxyl groups, while the signal of deposited salt-Na₂CO₃, which is not connected to surface hydroxyl groups, is completely suppressed. ¹H{²³Na} spin echo double resonance experiments reveal the surface modification in more detail. At low Na⁺ coverage (5%, 10%), the acidic hydroxyl groups are preferentially coordinated with sodium ions, while both the acidic and the basic hydroxyl groups are accessible for sodium ions at high coordination that causes proton of the OH groups to be easily dissolved, which is evidenced by the fact that with calcination temperature of the catalysts increasing, the acidic hydroxyl groups are preferentially removed and only the basic hydroxyl groups remain when the calcination temperature is raised to 600℃.     

Progress of phase-field investigations of γrafting in nickel-base single-crystal superalloys

With the development of nucleation theory,the calculation of phase diagrams(CALPHAD)method and microscopic elasto-plasticity mechanics,it is possible to apply the phase-field method to simulate the γrafting behavior of nickel-base single-crystal superalloys under the conditions of heat treatment,fatigue and creep testing.Based on the experimental progress in γrafting behavior and in combination with the microstructural simulation of the precipitation and rafting of c0phase,this paper reviews the phase-field investigation of γrafting in nickel–base single-crystal superalloys.     

Investigation on the homogenization treatment and element segregation on the microstructure of a γ/γ'-cobalt-based superalloy

The aim of the present study was to investigate the effect of element segregation on the microstructure and γ' phase in a γ/γ' cobalt-based superalloy. Several samples were prepared from a cast alloy and homogenized at 1300℃ for different times, with a maximum of 24 h. A microstructural study of the cast alloy using wavelength-dispersive spectroscopic analysis revealed that elements such as Al, Ti, and Ni segregated mostly within interdendritic regions, whereas W atoms were segregated within dendrite cores. With an increase in homogenization time, segregation decreased and the initial dendritic structure was eliminated. Field-emission scanning electron microscopy micrographs showed that the γ' phases in the cores and interdendritic regions of the as-cast alloy were 392 and 124 nm, respectively. The size difference of γ' was found to be due to the different segregation behaviors of constituent elements during solidification. After homogenization, particularly after 16 h, segregation decreased; thus, the size, chemical composition, and hardness of the precipitated γ' phase was mostly uniform throughout the samples.     

Study on the Synthesis of γ-aminopropyltriethoxysilane Modified Montmorillonite Supported Hydroxysulfonamide

1 Results A novel chiral hydroxysulfonamides,which have hydroxysulfonamide structures,are designed and synthesized from natural camphor.It has been studied for the application as chiral catalyst.This class of ligands can be used in many reactions that are catalysed by amino alcohol ligands.In this paper,we prepared a novel chiral hydroxysulfonamides by immobilization of on MMT modified by γ-aminopropyltriethoxysilane.The MMT was first pretreated with hydrochloric acid according to a reported patent[1]. ...     

Structural Changes of Polyethylene Terephthalate Fibers Grafted by Acrylamide

A group of grafted PET fibers with different graft yield are formed by grafting acrylamide onto the PET main chains. The structure of grafted fibers are studied by scanning electronic microscope ( SEM ), infra-red spectrophotometer ( IR ), and differential scanning calorimetry(DSC). At the same time, the moisture regain, dyeability, strength, and elongation at break of the samples are measured and their relations with structural changes are discussed. Compared with ungrafted fiber, shape of the fiber cross-section, IR characteristic absorption peaks, and melting behavior of the grafted fibers have been changed, causing the fiber dyeability and moisture regain to be increased, and mechanical properties to be changed.     

Damage of Interconnects by Electromigration Induced Surface Evolution

ＤａｍａｇｅｏｆＩｎｔｅｒｃｏｎｎｅｃｔｓｂｙＥｌｅｃｔｒｏｍｉｇｒａｔｉｏｎＩｎｄｕｃｅｄＳｕｒｆａｃｅＥｖｏｌｕｔｉｏｎ＊ＺｈａｏＺｈｉｊｕｎ（赵智军），ＹａｎｇＷｅｉ（杨卫）ＤｅｐａｒｔｍｅｎｔｏｆＥｎｇｉｎｅｅｒｉｎｇＭｅｃｈａｎｉｃｓ，Ｔｓ...     

Preparation and Properties of Super-hydrophobic Surface by Fluorinated Copolymers

1 Rusults Fig.1 Surface morphologies of the PMMA-PFAEA copolymer filmsa-e, Random copolymer, a-e, synthesized by micro emulsion polymerization,a)b), MMA:FAEA=2:1, c) d), MMA:FAEA=5:1; e) synthesized by solution polymerization, MMA:FAEA=7:3; f) Block copolymer, synthesized by RAFT polymerization, MMA:FAEA=4:1, all solution concentration 1×10-2g/mL Super-hydrophobic surfaces have attracted significant attention recently, and various preparing methods have been reported. Besides these preparing methods, solvent evaporation induced phase separation was relatively simple, but only block copolymers or polymer blends were reported successfully applied[1], and usually some complicate post-procedures or rigorous special environment were essential. Herein we reported a simple way to prepare a lotus-leaf like super-hydrophobic just by one-step casting the copolymer solution onto a solid surface. The as-prepared films represented very good super-hydrophobic ability even without further modification.     

Study on the Synthesis of Octyl Acetate by Phosphotungstate Heteropolyacid with Keggin Structure

1 Results Octyl Acetate is an important chemical material.It is widely used as solvent in many industries,such as plasterer,artificial leather,and lacquer varnish,spice and medicine industries.At the present time,it is prepared with acetic acid and 1-octanol in industry,by using sulfuric acid as the catalyst.This technique has many shortcomings,which include erosion of facility,many side reactions and difficulties of post-treatment.The most severe problem is its pollution to the environment[1-2],so this technique should be forbidden.Those researches into etherification catalysis by solid acids have been carried out in research years for overcoming the weakness.Among these,great importance has been attached to support heteropolyacid by more and more researchers[3-4].     

Influence of Damage Evolution on the Failure Surface of Concrete

0 IntroductionTihse a f agilruardeu aolf pcroonccerseste wshuibcjhec itsed ditfofe ernenvitr ofrnommentthale afcatiilounrespatternin general strengthtest .The change of material statescaused by the damage evolution will affect the concretestrengthin a certain kind of concrete.For years ,domestic studies have focused on the effect ofabominable environmental factors on mechanical property ofconcrete,and have resulted in some achievements[1-12]. Thestudies of some current research results reveal …     

A Study on the Surface Structures of Viscose-based Activated Carbon Fiber by FT-IR Spectroscopy and XPS

Using viscose fiber (VF) as starting material and common steam as activating agent, formation of oxygen structures in activated carbon fiber is investigated. In the preparation of samples, VF was first heated at temperatures between 450℃ and 900℃ in N_2 artmosphere. Then, in a successive activation stage, the product carbonized at 600℃ was activated in steam at 450-900℃ for 30 min, and at 600℃ for 5-30 min. The other carbonization products were activated at 600 and 900℃ for 30 min respectively. The products activated at 900℃ were then activated at 450℃ for 30 min again. The starting materiah carbonized products and all activation products were examined by FT-IR spectroscopy and some products were examined by X-ray photoelectron spectroscope (XPS). And the yields of the carbonized and activated products were calculated. By analysing these spectra, the amount of oxygen-containing functional groups of the activated products attained under various activation time, various activation temperature and     

Some Aspects of the Catalytic Organic Synthesis

1 Results Catalytic reactions are gaining importance due to its low cost, operational simplicity, high efficiency and selectivity. It is also getting much attention in green synthesis. Many useful organic reactions, including the acylation of alcohols and aldehydes, carbon-carbon, carbon-nitrogen, carbon-sulfur bond forming and oxidation reactions are carried out by catalyst. We are exploring the catalytic acylation of alcohols and aldehydes in a simple and efficient manner. Catalytic activation of unreactive species such as CFBr3 and subsequent addition to olefins has also been explored. Methods so far developed in last few years will be presented.K     

Influence of the Specific Surface of Polyester Supermicrofibre on the Dyeing Properties with Disperse Dyes

The influence of the polyester supermicrofiber specific surface on the dyeing properties of these fibres is studied with the purified disperse dye in this study. How the dyeing properties vary with the specific surface is shown. The dyeing properties mainly include dye saturation value, affinity, rate of dye uptake and equilibrium dye uptake etc. The relation between dye sorption behavior and the specific surface of the supermicrofibres is discussed.     

Thermodynamics of the Single-Step Synthesis of Dimethyl Ether from Syngas

A detailed thermodynamic analysis of single-step synthesis of dimethyl ether (DME) from syngas has been performed. From experiments and theoretical calculations, a suitable thermodynamic model based on Reid‘s thermodynamic data and the Soave-Redlich-Kwong equation of state was determined. Using thism model, a careful analysis of direct synthesis of dimethyl ether from syngas was carried out. Reaction synergy in the synthesis can greatly improve CO conversion and DME yield. Lower temperatures and higher pressures favor higher CO conversion and DME yield. Compared to methanol synthesis, however, the temperature has a smaller effect on the reaction. The direct synthesis of dimethyl ether can exploit CO-rich syngas efficiently due to the maximum DME yield obtained at H2/(CO CO2) mole ratio =1. A small amount of CO2 in the reactant mixture has little effect on the reaction. Under conditions of H2/(CO CO2) feedstock, water in the system can improve the reaction performance.     

Studies of the Synthesis of Biomarkers(Part15) Synthesis of1,3-Eicosanediol and 1,3-Octacosanediol

ＳｔｕｄｉｅｓｏｆｔｈｅＳｙｎｔｈｅｓｉｓｏｆＢｉｏｍａｒｋｅｒｓ（Ｐａｒｔ１５〔１〕）Ｓｙｎｔｈｅｓｉｓｏｆ１，３－Ｅｉｃｏｓａｎｅｄｉｏｌａｎｄ１，３－Ｏｃｔａｃｏｓａｎｅｄｉｏｌ＊ＬｉＴｏｎｇｓｈｕａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔ...     

Coarsening behavior of γ′ and γ″ phases in GH4169 superalloy by electric field treatment

The coarsening behaviors of γ′ and γ″ phases in GH4169 alloy aged at 1023 and 1073 K with electric field treatment (EFT) were investigated by transmission electron microscopy (TEM) and positron annihilation lifetime spectroscopy (PALS). It is demonstrated that precipitation coarsening occurs, and the growth activation energies of γ′ and γ″ phases can be decreased to 115.6 and 198.1 kJ·mol?1, respectively, by applying the electric field. The formation of a large number of vacancies in the matrix is induced by EFT. Due to the occurrence of vacancy migration, the diffusion coefficients of Al and Nb atoms are increased to be 1.6–5.0 times larger than those without EFT at 1023 or 1073 K. Furthermore, the formation of vacancy clusters is promoted by EFT, and the increase in strain energy for the coarsening of γ′ and γ″ phases can be counterbalanced by the formation of vacancy clusters.     

Copolymers of Styrene with Conjugated Dienes by Titanium Catalysts:Synthesis,Characterization and Evaluation of the Mechanical Properties

1 Results Polymerization of butadiene,isoprene and styrene and binary copolymerization of styrene with butadiene and isoprene were investigated using the catalyst Ti(η5-C5H5)(η2-MBMP)Cl (1) (MBMP=2,2′-methylenebis(6-tert-butyl-4-methylphenoxo) activated with methylaluminoxane (MAO).Syndiotactic polystyrene, cis-1,4- polybutadiene and cis-1,4-polyisoprene were obtained in good yields at 50 °C.Binary copolymerization of styrene with butadiene yielded block copolymers containing segments of cis-1,4-polybutadiene and crystalline syndiotactic polystyrene. Novel pseudorandom copolymers of styrene with isoprene were synthesized using the 1/MAO catalyst.The 13C NMR chemical shifts of the carbon atoms diagnostic of the different monomer diads and triads were predicted and assigned using properly calculated additive shift factors.Despite the syndiotactic arrangement of the styrene homosequences,the styrene-co-isoprene polymers are completely soluble in organic solvents and completely amorphous also at high styrene concentration.     

Synthesis of layered LiMnO2 by in situ oxidationintercalation and a study of the reaction mechanism and electrochemical performance

Lithium-ion batteries have become the main candi-date for rechargeable power sources in current electronicproducts because of their high open circuit voltage, highenergy density, longevity and absence of memory effect.Layered LiCoO2 has been used commerci…     

Study on Surface Modification of Glass Bead by a Block Copolymer Coupling Agent

A tri-block copolymer coupling agent polystyreneblock-poly （n-butyl-acrylate）-block-poly （y-methacryloxypro pylt rimethoxysilane）（PS-b-PnBA-b-PMPS） was synthesized by atom transfer radical polymerization （ATRP）, and its molecular structure was characterized by fourier-transform infrared spectra, hydrogen nuclear magnetic resonance and gel permeation chromatography. The glass bead was treated with the block copolymer coupling agent, and then studied by transmission electron microscopy. The result showed that strong interaction was formed between the block copolymer coupling agent and the surface of glass bead, and then the block of poly（n-butylacrylate） formed a layer of film on the surface.     

Application of ANSYS 3D FEM in Studies of Surface Deformation Caused by Pipe Jacking

By using site observation data and establishing 3D model using ANSYS software,this paper has discussed the strain change of stratum stress during process of jacking-in and the im-pact of machine head on ground surface under different frontal resistances. Analysis of the two cases shows that soil pressure reaches its maximum point when the soil is right above machine head,and soil stress will gradually decline when machine head passes over it. It also shows that impact brought by pipe-jacking construction on stress change of the surrounding soil is limited. The thesis suggest that road surface should be consolidated and soil condition be improved before construction to prevent loss and disaster caused by road surface deformation,jacking force can be increased so that jacking efficiency can be enhanced when ground stratum is well filled with soil,but the frontal resistance facing machine head should be equal to surrounding soil pressure in order to avoid rise of ground surface.     

Alignment Mechanism of Liquid Crystal Molecules on the Fluorated Polyimide Surface

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