Succinic acid adsorption from fermentation broth and regeneration

More than 25 sorbents were tested for uptake of succinic acid from aqueous solutions. The best resins were then tested for successive loading and regeneration using hotwater. The key desired properties for an ideal sorbent are high capacity, complete stable regenerability, and specificity for the product. The best resins have a stable capacity of about 0.06 g of succinic acid/g of resin at moderate concentrations (1–5 g/L) of succinic acid. Several sorbents were tested more exhaustively for uptake of succinic acid and for successive loading and regeneration using hot water. One resin, XUS 40285, has a good stable isotherm capacity, prefers succinate over glucose, and has good capacities at both acidic and neutral pH. Succinic acid was removed from simulated media containing salts, succinic acid, acetic acid, and sugar using a packed column of sorbent resin, XUS 40285. The fermentation byproduct, acetate, was completely separated from succinate. A simple hot water regeneration successfully concentrated succinate from 10 g/L (inlet) to 40–110 g/L in the effluent. If successful, this would lower separation costs by reducing the need for chemicals for the initial purification step. Despie promising initial results of good capacity (0.06 g of succinic/g of sorbent), 70% recovery using hot water, and a recovered concentration of >100 g/L, this regeneration was not stable over 10 cycles in the column. Alternative regeneration schemes using acid and base were examined. Two (XUS 40285 and XFS-40422) showed both good stable capacities for succinic acid over 10 cycles and >95% recovery in a batch operation using a modified extraction procedure combining acid and hot water washes. These resins showed comparable results with actual broth.     

焊接自动化专业引入机器人离线编程的教学探索

机器人焊接已成为焊接自动化技术现代化的主要标志。文中通过阐述机器人离线编程系统的组成原理和主流软件，认为须在焊接自动化专业构筑起机器人离线编程的相关课程体系，才可将机器人离线编程技术引入焊接自动化专业。以此提升焊接自动化的理论和实践教学，提高学生的职业技能。     

数学建模与素质教育

面对二十一世纪知识经济的挑战 ,我国高等教育模式应由应试教育 ,专业教育向素质教育转变 ,培养学生自主意识 ,效率意识 ,竞争意识 ,创新意识和民主意识 ,即高校教育应重视大学生的创新能力、实践能力和创业精神 ,普遍提高大学生的人文素质和科学素质 .本文拟就提高大学生素质的有效层面 ,对开展数学建模教学与实践进行深入分析 ,以窥探数学建模与素质教育之关系 .在深入把握数学建模教学与实践内涵的同时 ,分析得出这种以不打扰现行正常秩序的教育是提高大学生素质的有效途径之一     

Spectral Domain Analysis of Coaxial Cavities

Coaxial cavities are used in high power gyrotrons as the beam-wave interaction structure. Much research has been devoted to their mode selective properties. A coaxial cavity lacks a sharp boundary at its open end, so it has some physical features that can only be observed using a spectral model, such as frequency-dependent field profiles and mode overlapping effects. These properties are important since cold tests are usually conducted in the frequency domain. This study applies the incident/reflected wave boundary condition to the wave equation of a weakly irregular coaxial waveguide. The resistivity of the wall is considered in the analysis. Calculations reveal that the fixed-position spectrum yields an uncertain resonant frequency and quality factor. Although the maximum-field spectrum can uniquely determine the properties of the coaxial cavity, the resonant frequency obtained using the maximum-field spectral model is inconsistent with that obtained using the temporal model. The field-energy spectrum explains the low Q nature of the coaxial cavity. Moreover, resonant frequencies evaluated using the field-energy spectrum agree precisely with those evaluated using the temporal model.     

Henry Reaction in Aqueous Media：Chemoselective Addition of Aldehydes

The chemoselective addition of aldehydes in aquoues medium was obtained under mild condition using improved Henry reaction.     

Simultaneous determination of cloramphenicol, salicylic acid and resorcinol by capillary zone electrophoresis and its application to pharmaceutical dosage forms

This study demonstrates the separation of active ingredients in acne formulations (salicylic acid, cloramphenicol and resorcinol in presence of azulene) by capillary zone electrophoresis. Factors affecting their separations were the buffer pH and concentration, applied voltage, sample preparation, and presence of additives. Optimun results were obtained with a 50 mM sodium tetraborate-50 mM sodium phosphate, pH 9.0. The carrier electrolyte gave baseline separation with good resolution, short migration times (<6 min), great reproducibility and accuracy. Calibration plots were linear over at least three orders of magnitude of analyte concentrations, the lower limits of detection being within the range 0.39-1.25 μg ml⁻¹. The procedure was fast and reliable and commercial pharmaceuticals could be analysed without prior sample clean-up procedure.     

Influence of moisture on the viscoelastic relaxations in long aliphatic chain contained semiaromatic polyamide, (PA9‐T) fiber

The effect of moisture on the mechanical relaxation processes of semiaromatic semicrystalline polyamides synthesized by a long‐chain aliphatic diamine and terephthalic acid was investigated by dynamic viscoelastic analysis (DVA) and differential scanning calorimetry (DSC). Moreover, the implication of moisture with the amorphous and crystalline domains was also examined by temperature‐dependent wide‐angle X‐ray diffraction and Fourier transform infrared spectra. The characteristics of the relaxations such as α, β, γ, and the pronounced peak shoulder appeared at 25–100 °C in DVA tan δ curves were found to be strongly susceptible to the presence of moisture. With moisture evaporation, the peak shoulder of 25–100 °C and the β‐relaxation disappeared. The former is anticipated to originate from to the side group motion of hydrogen‐bonded water, whereas the later one is from the motions of the amide–water complex units. With the disappearance of the β‐relaxation, the γ‐relaxation appeared simultaneously in much lower temperatures and ultimately coupled with the δ‐relaxation. The γ‐relaxation is attributed to be associated with the molecular motion of the amide group and δ‐relaxation with for the motion of the methylene units. The existence of two types of water was identified in the polymer, namely, tightly bound and loosely bound. The tightly bound water is believed to be directly connected by hydrogen bonding with the strong polar groups and the loosely bound water weakly links with those connected water making hydrogen bridges. The moisture acts as a plasticizer in the polymer matrix, which causes quite a large depression in its glass transition temperature (T_g). WAXD and FTIR studies corroborated the existence of water solely in amorphous regions, i.e., no rapport of water with the crystalline parts. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2878–2891, 2003     

火力发电厂废水中悬浮物处理的影响因素探讨

对火力发电厂废水中悬浮物处理的影响因素如pH值、水温、接触介质、进水水质、混凝剂加入量等进行分析，对主要影响因素水温和混凝剂加入量进行了试验分析，制定出废水悬浮物处理的合理方案。     

Dispersion analysis of the least‐squares finite‐element shallow‐water system

The frequency or dispersion relation for the least‐squares mixed formulation of the shallow‐water equations is analysed. We consider the use of different approximation spaces corresponding to co‐located and staggered meshes, respectively. The study includes the effect of Coriolis, and the dispersion properties are compared analytically and graphically with those of the mixed Galerkin formulation. Numerical solutions of a test problem to simulate slow Rossby modes illustrate the theoretical results. Copyright © 2003 John Wiley & Sons, Ltd.     

Experimental analysis of current and deformation of ion-exchange polymer metal composite actuators

In this paper we describe the experimental analysis of a novel ion-exchange polymer metal composite (IPMC) actuator under large external voltage. The experimental analysis is supplemented with a coupled thermodynamic model, which includes mass transport across the thickness of the polymer actuator, chemical reactions at boundaries, and deformation as a function of the solvent (water) distribution. In this paper, the case of large electrode potentials (over 1.2 V) has been analyzed experimentally and theoretically. At these voltage levels, electrochemical reactions take place at both electrodes. These are used in the framework of overpotential theory to develop boundary conditions for the water transport in the bulk of polymer. The model is then simplified to a three-component system comprised of a fixed negatively charged polymeric matrix, protons, and free water molecules within the polymer matrix. Among these species, water molecules are considered to be the dominant species responsible for the deformation of the IPMC actuators. Experiments conducted at different initial water contents are described and discussed in the context of the proposed deformation mechanism. Comparison of numerical simulations with experimental data shows good agreement.