烷基羧酸钠与β—环糊精包结物稳定常数的测定

用表面张力法研究了基羟酸钠与β－环状糊精形成的包结物。实验结果表明表面张力法可以作为一种行之有效的方法确定表面活性剂与β－ＣＤ形成包结物的稳定常数,发现在表面活性剂浓不变时,增加β－ＣＤ的浓度溶液的表面张力上升,并达到纯水的表面张力值。     

Br(o)nsted酸性离子液体中苯甲酸酯、苄酯的无溶剂微波合成

该文以1-甲基咪唑、吡啶、苄基氯、硫酸、磷酸为原料,合成了4种Brnsted 酸性离子液体:1-甲基-3-苄基咪唑硫酸氢根盐(a),1-甲基-3-苄基咪唑磷酸二氢根盐(b),N-苄基吡啶硫酸氢根盐(c),N-苄基吡啶磷酸二氢根盐(d),以它们作为催化剂和反应介质,考察了苯甲酸与系列脂肪醇、苄醇与系列脂肪酸、苯甲酸在无溶剂和微波辐射反应条件下的Fischer酯化反应,结果表明,当苯甲酸或苄醇与离子液体的摩尔比为1∶ 0.5时,无需外加催化剂,反应即可在化学计量条件下进行,12～20 min完成反应,苯甲酸酯与苄酯的收率分别为77%～98%和78%～98.5%,气相色谱纯度≥95%.离子液体循环使用3次,催化活性仅下降1.8%～3.4%.     

Co-Mn-Br液相催化氧化β-甲基萘制β-萘甲酸

在高压反应釜中考察了操作方式、催化剂配比及用量、溶剂用量、反应压力、反应温度及添加水对Co-Mn-Br液相催化氧化β-甲基萘制β-萘甲酸反应的影响.结果表明,恒压操作方式优于分步恒压操作方式.甲基萘催化氧化体系存在明显的诱导期,时间长短与催化剂组成和反应条件有关.催化剂中Co、Br的量多时氧化反应快,但Br的量增多导致...     

紫外可见分光光度法在共轭亚油酸定量分析中的应用

采用UV - 91 0 0型紫外可见分光光度计 ,测定了由植物油脂制得的共轭亚油酸、共轭亚油酸甲酯、共轭亚油酸三甘酯在不同浓度时在 2 0 0nm - 30 0nm的吸光度 ,绘制出样品在不同浓度时的吸光度曲线 ,找出适宜的浓度范围 ,用MicrocalSoftwareOriginVersion 4.0做回归分析 ,由线性回归给出样品浓度和吸光度的线性关系 ,为对实验结果进行检验和校正 ,采用惠普 845 2A二极管阵列分光光度计测定了同一批样品在不同浓度范围内的吸光度 ,利用PEAutosystemXL -TurboMass测得样品中共轭亚油酸准确浓度 ,结合回归系数给出了用紫外可见分光光度计快速测定样品中共轭亚油酸含量的经验公式     

Silicon Force Transducer for Extraluminal Measurement of Oviduct Contractile Activity

A miniature, implantable force transducer has been developed for the extraluminal measurement of segmental smooth muscle contractility and has been applied to the oviduct in the Macaca mulatta. The force transducer makes use of a commercially available piezoresistive silicon strain sensor bonded to a flexible metal strip. The device is housed in a tissue compatible, gas sterilizable tubule upon which are placed sutures for subsequent extraluminal attachment to an organ.     

Replication Route Synthesis of Mesoporous Titanium–Cobalt Oxides and Their Photocatalytic Activity in the Degradation of Methyl Orange

Mesoporous Ti–Co oxides were synthesized via a replication route, using a 3-D wormlike mesoporous silica as template and tetra-tert-butyl orthotitanate (TBOT) and Co(NO₃)₂ as source materials. The prepared materials were characterized by X-ray diffraction (XRD), N₂-physisorption, TEM, EDS, and UV/Vis-DRS and found to possess a spherical morphology and a 3-D wormhole-like mesoporous structure, with the average pore size between 4.5 and 16.0 nm. The pore walls consisted mainly of a cobalt-incorporated anatase phase. The Co³⁺ ions were generated in the replicated mesoporous Co–Ti oxides, via the transfer of electrons from Co²⁺ to Ti⁴⁺ ions. The formation of cobalt-incorporated anatase phase and Co³⁺ ions were both favored by larger Co/Ti atomic ratios and by relatively low calcination temperatures. The specific surface area decreased and the mesopore sizes increased, with increasing Co/Ti atomic ratio or calcination temperature. The average crystal size of the anatase phase decreased with increasing Co/Ti atomic ratio but increased with increasing calcination temperature. The photocatalytic activity of the replicated mesoporous Co–Ti oxides in the degradation of methyl orange dye was investigated. It was observed that the photocatalytic activity increased with increasing Co/Ti atomic ratio and exhibited a maximum with increasing calcination temperature. With the exception of those prepared at too high calcination temperatures, the replicated mesoporous Co–Ti oxides were much more active than the pure titania. It is concluded that, in addition to a higher diffusion, the cobalt-containing anatase, as the active phase, and the Co³⁺ ions, as the active sites, are responsible for the high photocatalytic activity of the replicated mesoporous Co–Ti oxide.     

Effect of a surface active pyrrole on the conductivity of polypyrrole composites

A surface active pyrrole, which has a long hydrophobic chain attached to the 3 position of the pyrrole ring, is used to modify the surface properties of the pores of a porous, crosslinked polystyrene. The latter is prepared starting from a concentrated emulsion (an emulsion with a large volume fraction of the dispersed phase, here 0.81) of water dispersed in a continuous medium composed of styrene, divinyl benzene, a suitable surfactant, an initiator, and the surface active pyrrole. This modified crosslinked porous medium is emplyed as the host for a polypyrrole composite that is prepared first by imbibing the host with a solution of pyrrole and subsequently with an oxidant solution. The latter plays the role of catalyst for polymerization as well as the role of dopant. The presence of the head groups of 3-alkyl pyrrole molecules on the surface of the pores of the host polymer increases the affinity of the surface for pyrrole. The improved wetting thus achieved for the pyrrole solution ensures a higher connectivity among the pyrrole films present on the internal surface of the host polymer and increases the conductivity of the polypyrrole composites by a factor of 2 to 14, depending upon the solvents employed for pyrrole and oxidant.     

Organically modified silica sol-mediated capillary electrophoresis

We describe in this paper the use of ormosil (organically modified silica) sols as additives to the run buffer for selectivity manipulations between solutes in capillary electrophoresis. CE systems that contain sol additives in the run buffer can be thought of as pseudocapillary electrochromatography. Three sols based on different types of silanes were studied. Methyltrimethoxysilane (MTMOS)-based sol was found to improve selectivities between various aromatic acids. Aminopropyltrimethoxysilane (APS) sol interacts differently with structural isomers of aromatic acids than does MTMOS. At low pH with APS sol in the run buffer, neutral solutes can be separated, as well. The separation of the neutral solutes seems to be facilitated by the formation of hydrogen bonds between the solutes and the APS sol. APS and N-[3-(trimethoxysilyl)propyl]-ethylenediamine (EDAS) affect the separation of the same compounds differently, thus indicating that even small changes of the functional groups of the sol have pronounced effect on the interactions between the sols and the solutes.     

ADSORPTION ISOTHERMS AND CATALYST SELECTIVITY FOR A UNIFORM SURFACE: THE ROLE OF MULTIPLE LANDING AREAS

In general a gas phase species can be present simultaneously in more than one adsorbed form on a uniform solid surface. The different adsorbed forms tie up different combinations of surface sites. Each such combination is termed a landing area. The different adsorbed forms present on the surface of a catalyst may form different products. (In the more general case, each different adsorbed form yields a different distribution of a set of products.) Hence the relative amount of each adsorbed form and landing area present on the surface determines the selectivity of the solid catalyst. The variation of the landing area distribution with temperature and partial pressure of the gas phase species is examined in the first part of this work. In general, increasing the pressure or decreasing the temperature leads to the relative decrease of molecules adsorbed on landing areas consisting of larger number of sites and the relative increase of molecules adsorbed on smaller landing areas. The kinetics of metal catalyzed skeletal isomerization and hydrogenoly-sis of hydrocarbons on supported metal catalysts is examined in the framework of the landing area in the second part of this work. A simple model for the variation of reaction order with pressure agrees with experimental data from other laboratories.