Effect of additives on formation of natural gas hydrate

The formation of natural gas hydrate (NGH) is studied in this work. Kinetics data of hydrate formation with no agitation were collected at various concentrations of the aqueous solutions with different additives such as alkylpolyglucside, sodium dodecyl benzene sulfonate and potassium oxalate monohydrate. Various kinds of additive increased the formation rates of NGH and its storage capacity and reduced the induction time of NGH formation. Moreover, the storage capacity, the induction time and the hydrate formation rate were influenced by the concentration of the aqueous solution.     

Synthesis,characterization, and thermal properties of phosphorus‐containing,wholly aromatic thermotropic copolyesters

A series of phosphorus‐containing, wholly aromatic thermotropic copolyesters from acetylated 2‐(6‐oxide‐6H‐dibenz〈c,e〉〈1,2〉oxa phosphorin‐6‐yl)‐1,4‐dihydroxy phenylene, p‐acetoxybenzoic acid, terephthalic acid, and isophthalic acid were prepared by melting polycondensation. The structure and basic properties of the polymers, such as the glass‐transition temperature (T_g), melting temperature (T_m), thermal stability, crystallinity, and liquid crystallinity, were investigated with Fourier transform infrared, elemental analysis, differential scanning calorimetry (DSC), thermogravimetric analysis, wide‐angle X‐ray diffraction, and hot‐stage polarizing optical microscopy. The copolyesters had relatively high T_g values ranging from 183 to 192°C. The T_m values obtained from DSC curves for samples P‐20 and P‐25 were 290 and 287°C, respectively (where the number in the sample name indicates the molar fraction of the phosphorus‐containing monomer in the reactants). The initial flow temperatures of other samples observed with hot‐stage polarizing microscopy were 271–290°C. The 5% degradation temperatures in nitrogen ranged from 431 to 462°C, and the char yields at 640°C were 41–52%. All the copolyesters, except P‐40, were thermotropic and nematic. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1278–1284, 2002     

Influence of Grain Size on Ferroelastic Toughening and Piezoelectric Behavior of Lead Zirconate Titanate

Lead zirconate titanate specimens, at composition Zr_{48.9+- 1.0}/ Ti_51.1+-1.0 of grain sizes ranging from 0.5 to 15 (μm were prepared by hot pressing. The fracture toughness showed a 40% increase in the fine-grained specimens. Poling produced anisotropy in the fracture toughness. A tensor representation for the fracture toughness, now a function of the crack plane normal and the poling direction, is developed. The maximum and minimum values in the toughness tensor are shown to be related to the unpoled toughness by a simple phenomenological relationship. We also find that the piezoelectric coefficient, d₃₃ , shows a slight increase for the fine-grained specimens, which is in conflict with the general view that smaller-grained materials can sustain vanishingly small values of spontaneous polarization.     

PVA-based activated carbon fibers with lotus root-like axially porous structure

A novel method was developed for the fabrication of activated carbon fiber (ACF) with wet spinning polyvinyl alcohol (PVA) fibers as the precursors. Through a combination of preoxidation, dehydration, carbonization and activation under a certain tension, PVA-based ACFs (PVA-ACFs) with high yields and good mechanical properties were obtained. The surface and cross-section morphologies, pore structures, surface geometries, surface functional groups and crystal structures of the PVA-ACFs were characterized using field emission scanning electron microscopy, low temperature nitrogen adsorption, Fourier transformed infrared spectrophotometry, X-ray photoelectron spectroscopy and X-ray power diffraction. All the PVA-ACF samples prepared had lotus root-like axially meso- and macroporous structures with the domination of micropores. Fractal geometries of PVA-ACFs deduced from nitrogen adsorption isotherms indicates that capillary force dominated in the interactions between nitrogen and the PVA-ACFs. The surface functional groups of the PVA-ACFs depend on the activating agents. Graphitoidal crystal structures were observed for the PVA-ACFs. The small crystal size and short range ordering between the crystallites ensured a high specific surface area of the PVA-ACFs.     

细胞激动素Kinetin合成的改进

介绍了用糠胺与腺嘌呤在催化条件下反应合成细胞激动素kinetin,该法原料易得,反应条件温和,产品收率及纯度都较高。     

Discourse cues to deception in the case of multiple receivers

Behavioral cues to deception are instrumental in detecting deception. As one of the primary sources of deception behavior, text has been analyzed at the level of sub-sentence or message but not the discourse of interaction. Additionally, empirical studies on cues to deception in the case of multiple receivers remain nonexistent. To fill these voids, we propose a discourse framework and six hypotheses about deception behaviors in a multi-receiver environment. The deception behaviors are operationalized by discourse features based on an analysis of real-world data. The results of statistical analysis validate the efficacy of discourse features in discriminating deceivers from truth-tellers.     

探讨回收污水中有用的物质

重油催化裂化等的污水含汽油、硫和氨，将汽油、硫和氨回收是哈尔滨石化分公司具有发展前景的项目。     

乡镇矿山科学管理出效益的体会

柳树沟磷矿开工时技术力量十分薄弱，以自己培养为主．广泛争取设计院等单位支持．基建工程严格按设计施工，并且建立健全各项规章制度，实行科学管理，安全生产文明生产，扩大生产规模，已由年产９万ｔ扩大到２０万ｔ，企业经济效益、社会效益十分显著，成为乡镇矿山典范，磷矿企业的标兵．     

Poly(3‐chlorothiophene) films prepared by the direct electrochemical oxidation of 3‐chlorothiophene in mixed electrolytes of boron trifluoride diethyl etherate and sulfuric acid

3‐Chlorothiophene (CT) was electrochemically polymerized in mixed electrolytes of a boron trifluoride diethyl etherate solution containing 0–20% (by volume) sulfuric acid. The oxidation potentials of the monomer in these media were measured to be only 1.06–1.31 V (vs Ag/AgCl). These values were much lower than that of CT in acetonitrile and 0.1 mol/L (Bu)₄NBF₄ (1.92 V vs Ag/AgCl). Poly(3‐chlorothiophene) (PCT) films with conductivities of 0.1–2 S cm^?1 were obtained. The structure, morphology, and electrochemical behavior of the PCT films also were investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 502–509, 2003     

Carbon dioxide reforming of methane to synthesis gas over supported Ni catalysts

Carbon dioxide reforming of methane to synthesis gas has been investigated over supported Ni catalysts in the temperature range of 500–850°C. Addition of CaO (10mol%) promoter to the Ni/γ-Al₂O₃ resulted in an increase of reaction rate and an improvement of catalyst stability, which may be related to enhanced reducibility of the promoted catalyst. The kinetic studies show that the overall reaction can be described by a Langmuir-Hinshelwood mechanistic scheme, assuming that methane dissociation is the rate determining step. In addition to adsorbed CO and formate species, three types of carbonaceous species, C, C_β and C_γ, were found to exist on the Ni catalyst. While the active C, species is suggested to be responsible for CO formation, the less active C_β and C_γ species are attributed to causing catalyst deactivation.