蒙脱土-聚合物纳米复合材料及其在油田开发中应用性能探讨

将工业品蒙脱土提纯，与铵盐进行离子交换，在PHP(HPAM)水溶液中冷冻干燥。得到蒙脱土的固态化纳米前驱物NPP。再用某种齐聚物包裹。得到核-壳结构颗粒(最大粒径0．5～2μm)，在单体聚合时颗粒剥离或分散，蒙脱土的粒径降至20～70nm，团聚颗粒占3％～5％，成为纳米复合材料(纳米颗粒)。介绍了2种纳米化前驱物的特性。超细颗粒与聚合物之间的强相互作用使纳米复合材料中聚合物的热降解性减小。用钻井液常规测定方法考察了所制备的纳米颗粒(主要是NPP—PHP纳米颗粒)悬浮液的流变及其他特性：增粘性远大于蒙脱土 PHP混合物浆；AV，PV，YP值对聚合物浓度很敏感；n、k值变化相对较小；在150℃热处理后粘度、滤失量、密度变化小；滤饼致密光滑；随聚合物浓度增大，pH迅速降至一恒定值(符合Kubo等的超微颗粒电中性理论)；AV值随NaCl加量增大而增大，随CaCl2加量增大而减小。在NPP—PHP泥饼中检出ZnS,CaS，CaCO3等物质，应为超细蒙脱土的生成物，生成反应有利于去除H2S和CO2，其不利影响有待研究。图5表2参12。     

Tetrazoles: Unique Capping Ligands and Precursors for Nanostructured Materials

Capping agents play an important role in the colloidal synthesis of nanomaterials because they control the nucleation and growth of particles, as well as their chemical and colloidal stability. During recent years tetrazole derivatives have proven to be advanced capping ligands for the stabilization of semiconductor and metal nanoparticles. Tetrazole‐capped nanoparticles can be prepared by solution‐phase or solventless single precursor approaches using metal derivatives of tetrazoles. The solventless thermolysis of metal tetrazolates can produce both individual semiconductor nanocrystals and nanostructured metal monolithic foams displaying low densities and high surface areas. Alternatively, highly porous nanoparticle 3D assemblies are achieved through the controllable aggregation of tetrazole‐capped particles in solutions. This approach allows for the preparation of non‐ordered hybrid structures consisting of different building blocks, such as mixed semiconductor and metal nanoparticle‐based (aero)gels with tunable compositions. Another unique property of tetrazoles is their complete thermal decomposition, forming only gaseous products, which is employed in the fabrication of organic‐free semiconductor films from tetrazole‐capped nanoparticles. After deposition and subsequent thermal treatment these films exhibit significantly improved electrical transport. The synthetic availability and advances in the functionalization of tetrazoles necessitate further design and study of tetrazole‐capped nanoparticles for various applications.     

Improving chocolate flavor in poor-quality cocoa almonds by enzymatic treatment

Abstract: This paper proposes a method to enzymatically treat poor‐quality cocoa almonds (known as “slate”) to ensure the formation of chocolate flavor precursors. The production of flavor precursors improves the quality of these almonds, which are usually responsible for the low quality of the liquor produced. Proteases and carboxypeptidases from different sources were tested under various conditions. The different treatments were evaluated by chemical analysis (hydrolysis efficiency) and sensory analysis of the treated material compared to good‐quality cocoa almonds. The results show that it is possible, through the use of microbial enzymes, to generate the mixture of compounds that will release, after roasting, the characteristic chocolate flavor in poor‐quality almonds. However, it is necessary to optimize the conditions of enzymatic treatment to obtain better results and thus establish a process that can be used for industrial purposes for manufacturing cocoa and chocolate. Practical Application: The basidiomycete Moniliophtora perniciosa is the causative agent of witches’ broom disease (WBD) of the cocoa tree, whose seeds are the source of chocolate. It is the most important phytopathological problem of cocoa‐producing areas of the American continent, and has decimated the Brazilian cocoa industry. In Bahia (Brazil), M. perniciosa was identified in 1989 and, as a consequence of its spreading, the annual production of cocoa almonds dropped from 450000 to 90000 tons within 12 y, reducing export values from an all‐time high of about US$ 1 billion to 110 million. The high incidence of WBD incapacitates Brazil to produce enough cocoa almonds even for the internal market, leading the country to import low‐quality cocoa almonds mainly from African countries. Our work proposes an enzymatic treatment to increase the quality of that cocoa almonds and, consequently, to improve the quality of the chocolate produced and consumed in the country.     

Occurrence and formation potential of N-nitrosodimethylamine in ground water and river water in Tokyo

N-nitrosodimethylamine (NDMA), a disinfection byproduct of water and wastewater treatment processes, is a potent carcinogen. We investigated its occurrence and the potential for its formation by chlorination (NDMA-FP_2Cl) and by chloramination (NDMA-FP_2NHCl) in ground water and river water in Tokyo. To characterize NDMA precursors, we revealed their molecular weight distributions in ground water and river water. We collected 23 ground water and 18 river water samples and analyzed NDMA by liquid chromatography-tandem mass spectrometry. NDMA-FP_2Cl was evaluated by chlorinating water samples with free chlorine for 24 h at pH 7.0 while residual free chlorine was kept at 1.0-2.0 mgCl₂/L. NDMA-FP_2NHCl was evaluated by dosing water samples with monochloramine at 140 mgCl₂/L for 10 days at pH 6.8. NDMA precursors and dissolved organic carbon (DOC) were fractionated by filtration through 30-, 3-, and 0.5 kDa membranes. NDMA concentrations were <0.5-5.2 ng/L (median: 0.9 ng/L) in ground water and <0.5-3.4 ng/L (2.2 ng/L) in river water. NDMA concentrations in ground water were slightly lower than or comparable to those in river water. Concentrations of NDMA-FP_2Cl were not much higher than concentrations of NDMA except in samples containing high concentrations of NH₃ and NDMA precursors. The increased NDMA was possibly caused by reactions between NDMA precursors and monochloramine unintentionally formed by the reaction between free chlorine and NH₃ in the samples. NDMA precursors ranged from 4 to 84 ng-NDMA eq./L in ground water and from 11 to 185 ng-NDMA eq./L in river water. Those in ground water were significantly lower than those in river water, suggesting that NDMA precursors were biodegraded, adsorbed, or volatilized during infiltration. The molecular weight of NDMA precursors in river water was dominant in the <0.5 kDa fraction, followed by 0.5-3 kDa. However, their distribution was inconsistent in ground water: one was dominant in the <0.5 kDa fraction, and the other in 0.5-3 kDa. Molecular weight distributions of NDMA precursors were very different from those of DOC. This is the first study to reveal the widespread occurrence and characterization of NDMA precursors in ground water.     

Psychosocial aspects of assessment and treatment of irritable bowel syndrome in adults and recurrent abdominal pain in children.

This article presents a selective review of psychosocial research on irritable bowel syndrome (IBS) in adults and on a possible developmental precursor, recurrent abdominal pain (RAP), in children. For IBS the authors provide a summary of epidemiology, of the psychological and psychiatric disturbances frequently found among IBS patients, and of the possible role of early abuse in IBS. A review of the psychosocial treatments for IBS finds strong evidence to support the efficacy of hypnotherapy, cognitive therapy, and brief psychodynamic psychotherapy. The research relating RAP to IBS is briefly reviewed, as is the research on its psychological treatment. Cognitive-behavioral therapy that combines operant elements and stress management has the strongest support as a treatment for RAP. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distinguished Scientific Awards for an Early Career Contribution to Psychology: Kenneth A. Dodge.

The Early Career Awards recognize the large number of excellent young psychologists. Recipients of this award may not have held a PhD for more than eight years. Three areas of psychology are considered each year. The areas considered for awards in 1984 were human learning/cognition, psychopathological, and physiological. Kenneth A. Dodge was recognized for contributions to the study of childhood precursors of psychopathology; for theoretical and empirical analyses illuminating the development of social competencies in children; and for innovative research relating children's social-information-processing skills to their social status, peer interaction patterns, antisocial behavior, and risk for future deviance. His work's importance is enhanced by its promising implications for early identification and prevention. In addition to a citation, a biography and bibliography of Dodge's works are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

湿化学法合成先驱体制备氮化硼纤维的研究

以硼酸和三聚氰胺为原料,采用湿化学法合成先驱体,在氮气气氛中制备出氮化硼(BN)纤维。用中和滴定法、红外吸收光谱(IR)、X射线衍射(XRD)、扫描电镜(SEM)对合成的先驱体及制得的BN纤维的氮含量、形貌及结构进行分析。结果表明合成温度1,700℃,保温时间3 h,氮气流量2 L/min时制得的BN纤维的氮含量为53.46%,达到理论值的95%。先驱体分子中存在B—N、N—H、C—O—C、—(B—N)—结构单元。用扫描电镜观察制得的BN纤维直径为2~10 靘,长径比为40~50。     

Hafnium carbide structural foams synthesized from polymer precursors

Hafnium carbide （HfC） was applied in space and aerospace due to its ultra high melting temperature, high specific strength and moderate oxidation resistance. A novel synthesizing method was used to produce low density and high strength HfC structural foams through the thermolysis and pyrolysis of Hf containing polymer precursors （mixing of hafiaium trifluoroacetylacetonate and epoxy） under vacuum atmosphere. The X-ray diffraction analysis shows that the produced foam is primarily composed of HfC containing 9%-10% HfO2. Several polymer powder compaction methods were used to improve the mechanical properties of HfC foam. Compression strengths of 200 MPa are achieved for HfC foams with density of 1.9 g/cm^3 （total porosity about 85%）. The proposed methodology of synthesizing HfC foam has the advantages of simple, inexpensive and less production time than alternate methods.     

Hydrothermal synthesis of precursors for Y-TZP/α-Al2O3 composite

A coprecipitated xerogel having the composition of 90 vol.% zirconia (3 mol% Y₂O₃) and remaining 10 vol.% alumina was crystallized under hydrothermal conditions by adopting conventional (110 °C for 7 days) or microwave (250 °C for 2 h) routes. The hydrothermal treatments of crystallization were performed in the presence of (KOH+K₂CO₃) (K), (CH₃)₄NOH (TMA), or (C₂H₅)₄NOH (TEA) mineralizer solutions at different concentrations.The role of the two different hydrothermal routes, of the nature and the concentration of the mineralizer solution on the thermal behaviour of the resulting powders are discussed.     

Preparation and Use of a Boron Nitride Precursor as Binder for the Densification of Boron Nitride

A precursor of boron nitride was prepared through the partial condensation of 2,4,6-trichloroborazine and bis-(trimethylsilyl)acetylene. This reaction was conducted at 100°C and is catalyzed by AlCl₃. The condensation product pyrolyzed at 800°C, producing trimethylsilyl chloride as a volatile product and a boron nitride rich residue containing 54 wt% of the initial weight. Mixtures of the precursor and commercial boron nitride were made and hot-pressed at 800°C and 27.6 MPa. A maximum density of 1.84 g/cm³ is reached at a loading corresponding to the deposition of 13 wt% residue derived from the precursor. Examination by analytical electron microscopy, including X-ray energy dispersive spectroscopy and electron energy loss spectroscopy analyses, revealed the location of material derived from the precursor in BN-binder composites through the presence of residual aluminum, silicon, and carbon. Crystallization of boron nitride from the precursor appears to have taken place, as deduced from the morphology of the phases observed and association with residual elements present in the binder.