Works of adhesion at the carbon fiber-liquid interface determined using a modified wetting technique

Works of adhesion W_SL between aqueous solutions with pH values in the range from 1 to 14 and carbon fibers from different sources, which were additionally treated in an inert atmosphere or in oxygen, were measured by use of a microbalance. These works of adhesion W_SL were found to show distinct stepwise dependencies on the pH value. The works of adhesion W_SL are attributed to dispersion interactions W_SL¹ and various acid-base interactions w_sl^ab—in the latter case between the acidic and basic surface groups of carbon and the various basic and acidic aqueous solutions.     

On the Predominant Electron-Donicity of Polar Solid Surfaces

The reasons for the predominant electron-donicity of almost all solid polar surfaces and its implications are discussed in this paper. By contact angle or interfacial tension measurements, the electron-accepting as well as the electron-donating properties of polar liquids can be ascertained, through the interplay between their energies of adhesion and cohesion. For the solid-liquid interface, direct interfacial tension measurements are not possible, but indirectly, solid/liquid interfacial tensions of polar systems can be obtained by contact angle measurement. However, as the energy of cohesion of a solid does not influence the contact angle formed by a liquid drop placed upon its surface, one can only measure the solid surface'ks residual polar property, manifested by the energy of adhesion between solid and liquid. This residual polar property is of necessity the dominant component; in most cases this turns out to be its electron donicity. When, by means of contact angle measurements with polar liquids, both electron-accepting and electron-donating potentials are found on a polar solid, it is most likely still partly covered with a polar liquid: usually water. The amount of residual water of hydration of a polar solid follows from its polar (Lewis acid-base) surface tension component (γ^AB). The degree of orientation of the residual water of hydration on a polar solid can be expressed by the ratio of the electron-donating to electron-accepting potentials (γ^⊖/γ^⊕), measured on the hydrated surface.     

One-step formation of ethyl methyl ketone from 1-butene and water on ultrastable Y-type zeolite catalyst

Proton exchanged ultrastable Y-type zeolite with silica/alumina = 40 showed a pronounced catalytic activity for the formation of ethyl methyl ketone directly from 1-butene and water. The formation rate of ethyl methyl ketone was much higher than those on MoO₃-based catalysts in the oxidation of 1-butene by oxygen. It was suggested that the basic site necessary for the formation of ethyl ketone directly from 1-butene and water would be the pentacoordinated Al.     

Chemical and morphological effects of blended sulfonated poly(styrene-isobutylene-styrene) and isopentylamine for direct methanol fuel cell applications

In this study, blend membranes based on a combination of sulfonated poly (styrene-isobutylene-styrene) (SIBS) with isopentylamine (IPA) were synthetized as potential candidates for direct methanol fuel cell (DMFC) applications. The impact of sulfonation level (57–93 mol%) and percentage of IPA incorporation (1, 3, and 5 wt%) were analyzed via different properties of the resulting membrane. FTIR analysis showed that IPA was successfully incorporated into the sulfonated polymer matrix and also confirmed the interaction between the sulfonic and amine groups. This interaction generates significant morphological changes in the nanostructure of the membranes that are evident through results of small angle x-ray scattering and atomic force microscopy analysis. Proton conductivity and methanol permeability of the membranes were also analyzed. Proton conductivity was significantly enhanced with the incorporation of IPA at an optimum loading, creating additional paths for the conduction of protons through the membrane. It was also sensitive to the morphological changes produced after the IPA incorporation and the interconnection between the ionic domains. Methanol permeability increased slightly due to the additional water domains and the inability of the isopentyl groups of IPA to block the free-volume in the membrane. Despite this, the selectivity (proton conductivity over methanol permeability) of the membranes was comparable to the state-of-the-art Nafion®, especially at an optimum IPA incorporation of 3 wt%.     

Alkylation of phenol with 1-propanol and 2-propanol over catalysts derived from hydrotalcite-like anionic clays

Vapour phase alkylation of phenol with 1-propanol and 2-propanol was carried out in a fixed-bed flow reactor over calcined magnesium aluminium hydrotalcites (MgAl-CHT) with Mg/Al atomic ratios 2, 3 and 4. MgAl 3.0-CHT showed higher phenol conversion (80% at 350C, in the alkylation of phenol with 1-propanol. Both O- and C-alkylations were found to be taking place without any skeletal isomerization of the propyl moiety, suggesting an S_N2 type mechanism. Isomorphous substitution of Mg²⁺ by Cu²⁺ or Ni²⁺ in the hydrotalcite framework resulted in the predominant C-alkylation to give 2-n-propylphenol (60–70%) with nearly 40–50% phenol conversion at 350C. When 2-propanol was used as an alkylating agent, the phenol conversion decreased over all these catalysts and the alkylation was noticed exclusively at C-centers. Comparison of the product selectivity at constant phenol conversion revealed that CuAl 3.0-CHT is more selective for 2-n-propylphenol and 2-isopropylphenol in the reaction of phenol with 1-propanol and 2-propanol respectively. The participation of a pair of acid-base sites in the calcined hydrotalcites for the alkylation reaction has been proposed. The acid-base properties of these catalysts have been examined by the decomposition of cyclohexanol as a test reaction. Analysis of the spent catalysts revealed that Cu²⁺ in CuO gets reduced into Cu¹⁺ and metallic copper during the reaction in the case of CuAl-CHT, while MgO and NiO phases of MgAl-CHT and NiAl-CHT are retained.     

红外光谱研究硬脂酸单分子膜与十八胺单分子膜之间的相互作用

研究了硬脂酸单分子膜和十八胺单分子膜两者间的相互作用.为了观察它们之间是否发生酸碱反应,分别把硬脂酸和十八胺的氯仿溶液滴加到气液界面上,形成两类物质的单分子膜区域.然后把这两种单分子膜在水气界面上混合.通过红外光谱研究表明:质子在两类单分子膜之间是很难转移的,同时红外光谱证明由硬脂酸单分子膜和十八胺单分子膜制备的混合LB膜主要由独立的硬脂酸区域和十八胺区域组成.     

Electrochemical behaviors of novel composite polymer electrolytes for lithium batteries

A novel composite polymer electrolyte was prepared by blending an appropriate amount of LiC104 and 10% (mass fraction) fumed SiO2 with the block copolymer of poly (ethylene oxide) (PEO) synthesized by poly (ethylene glycol) (PEG) 400 and CH2CI2.The ionic conductivity, electrochemical stability, interfacial characteristic and thermal behavior of the composite polymer electrolyte were studied by the measurements of AC impedance spectroscopy, linear sweep voltammetry and differential scanning calorimetry (DSC), respectively. The glass transition temperature acts as a function of salt concentration, which increases with the LiC104 content.Lewis acid-base model interaction mechanism was introduced to interpret the interactive relation between the filled fumed SiO2 and the lithium salt in the composite polymer electrolyte. Over the salt concentration range and the measured temperature, the maximum ionic conductivity of the composite polymer electrolyte (10^4.41 S/cm) appeared at EO/Li=25 (mole ratio) and 30~C, and the beginning oxidative degradation potential versus Li beyond 5 V.     

酸碱失衡与急性心血管疾病关系研究进展

急性心血管疾病作为内科常见疾病,病情进展快,病理变化复杂,常出现体内酸碱平衡紊乱,酸碱失衡尤其见于急性心肌梗死疾病中。临床研究表明,体内酸碱失衡可能会导致急性心血管系统损伤,影响疾病的预后,甚至导致心源性休克发生,因此各项酸碱监测指标对于急性心血管疾病的诊断、治疗监测和预后有着重要临床作用。     

A potent preparation method combining neutralization with microfluidization for rebamipide nanosuspensions and its in vivo evaluation

Backgrounds: Rebamipide (REB) is classified as a Biopharmaceutics Classification System (BCS) Class-IV compound with poor aqueous solubility and poor permeability. The local concentration in the mucosa makes REB exhibiting the therapeutic activities, and the strategy of increasing the dissolution rate has the possibility to improve the oral gastrointestinal (GI) distribution when using REB nanosuspensions.

Objective: The purpose of this work was to prepare REB nanosuspensions (REB-NSs) by combining neutralization with microfluidization to improve its dissolution rate and orally pharmacokinetic properties.

Methods: The feasibility of using acid-base neutralization and microfluidization to prepare REB-NSs was studied, and the preparation was optimized by central composite design (CCD). Physical states were characterized by using some technical methods, while the plasma drug concentration and GI distribution in rodents were determined.

Results: The experimental results identified a formulation with 10 mg/mL REB, 0.9% (w/v) Lutrol F127, and 0.6% (w/v) Kollidon 90F. The dissolution rate of the dried REB-NSs was faster than that of Mucosta^® tablets in different media, and the pharmacokinetic study showed a slight increase (1.3-fold and 1.1-fold) in the AUC_{0–12 h} compared with unprocessed conventional suspensions (CSs) and solutions. Also, the GI distribution of REB-NSs improved compared with REB-CSs, and this would be preferable to assist in protecting GI mucosa.

Conclusion: The REB-NSs prepared by the combining method exhibited a higher plasma drug concentration and superior GI distribution, thereby demonstrating positive results for preparing nanosuspensions of local effective BCS IV drugs with pH dependence such as REB by this method.     

常压酸碱法造纸新工艺的废水处理

简述了江西三森纸业有限公司采用的非木纤维常压酸碱法造纸新工艺流程,并进行了该工艺的清洁生产分析.根据该工艺的特点,分析了该公司采用"物化 生化"的废水处理方案的可行性,并提供了方案的设计参数和预期处理效果.