分段进水比对两级A/O-海绵填料工艺处理DMF废水的影响

采用两级A/O-海绵填料工艺处理DMF废水,探究一级A/O缺氧池(A1)和二级A/O缺氧池(A2)分段进水比(8∶2、7∶3、6∶4、5∶5)对系统脱氮除碳效能影响。结果表明,两级A/O-海绵填料工艺在不同分段进水比条件下均能实现对COD的高效去除,COD平均去除率均达到95%以上,而系统对TN、NO;-N和NH;-N的去除受分段进水比影响较大。在较高(8∶2和7∶3)分段进水比条件下,系统TN去除率为81.39%~89.03%,此时TN主要以NH₄⁺-N和NO₃^--N形式存在;当分段进水比减小为6∶4时,系统TN去除率达到最优值91.33%,出水NH₄⁺-N和NO₃^--N均明显低于其余进水比工况,分别降至8.04 mg/L和7.06 mg/L。因此通过优化两级A/O-海绵填料工艺分段进水比,可提升高浓度有机氮废水中难降解碳源的利用率与控制氨化反应进程,实现DMF废水有机氮的高效去除。     

The Effects of Different Heat Treatment Regimes on the Wear Properties of Fe-Based Composite Materials

Powder Metallurgy and Metal Ceramics - In this study, different heat treatment regimes, such as sintering, sintering with low-pressure cementation, and only low-pressure cementation were applied to...     

Dye‐affinity hollow‐fibres and their lysozyme adsorption–desorption characteristics

Dye‐affinity adsorption is increasingly used for protein separation. Hollow‐fibres have advantages as adsorbents in comparison to conventional bead supports because they are not compressible and can eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of polyamide hollow‐fibres to which Reactive Green HE‐4BD was attached for adsorption of lysozyme. The hollow‐fibre was characterized by scanning electron microscopy. These dye‐carrying hollow‐fibres (26.3 µmol g^?1) were used in the lysozyme adsorption–elution studies. The effect of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye‐attached hollow‐fibres was studied in a batch system. The non‐specific adsorption of lysozyme on the polyamide hollow‐fibres was 1.8 mg g^?1. Reactive Green HE‐4BD attachment significantly increased the lysozyme adsorption up to 41.1 mg g^?1. Langmuir adsorption model was found to be applicable in interpreting lead adsorption by Reactive Green HE‐4BD attached hollow fibres. Significant amount of the adsorbed lysozyme (up to 95%) was eluted in 1 h in the elution medium containing 1.0 M NaSCN at pH 8.0. In order to determine the effects of adsorption conditions on possible conformational changes of lysozyme structure, fluorescence spectrophotometry was employed. We concluded that polyamide dye‐affinity hollow‐fibres can be applied for lysozyme adsorption without causing any significant conformational changes. Repeated adsorption–elution processes showed that these dye‐attached hollow‐fibres are suitable for lysozyme adsorption. © 2001 Society of Chemical Industry     

Magnetic hydrophobic affinity nanobeads for lysozyme separation

N-Methacryloyl-l-phenylalanine (MAPA) containing poly(2-hydroxyethylmethacrylate) based magnetic [mag-poly(HEMA–MAPA)] nanobeads was prepared for lysozyme purification form chicken egg white. MAPA was synthesized by reacting methacryloyl chloride with l-phenylalanine methyl ester and provided hydrophobic functionality to the nanobeads. Size of mag-poly(HEMA–MAPA) nanobeads was 386 nm and obtained by surfactant free emulsion polymerization of HEMA and MAPA having a specific surface area of 580 m²/g. Mag-poly(HEMA–MAPA) nanobeads were characterized by FTIR, AFM, TEM, ESR, and elemental analysis. Lysozyme adsorption experiments were investigated under different conditions in batch system (i.e., medium pH, protein concentration, temperature, salt type). Lysozyme adsorption capacity of mag-poly(HEMA) and mag-poly(HEMA–MAPA) nanobeads from aqueous solutions was estimated as 24 and 517 mg/g, respectively. Lysozyme molecules were desorbed with 50% ethylene glycol solution with 98% recovery. It was observed that mag-poly(HEMA–MAPA) nanobeads can be used without significant decrease in lysozyme adsorption capacity after ten adsorption–desorption cycles. Mag-poly(HEMA–MAPA) nanobeads was used for the purification of lysozyme from chicken egg white. Purity of lysozyme was estimated by SDS-PAGE.     

Synthesis of bio‐based polymeric nanocomposites from acrylated epoxidized soybean oil and montmorillonite clay in the presence of a bio‐based intercalant

Polymeric nanocomposites were synthesized from functionalized soybean‐oil‐based polymer matrix and montmorillonite (MMT) clay using an in situ free radical polymerization reaction. Acrylated epoxidized soybean oil combined with styrene was used as the monomer. Organophilic MMT (OrgMMT) was obtained using a quaternized derivative of methyl oleate, which was synthesized from olive oil triglyceride, as a renewable intercalant. The resultant nanocomposites were characterized using X‐ray diffraction and atomic force microscopy. The effect of increased nanofiller loading on the thermal and mechanical properties of the nanocomposites was investigated using thermogravimetric analysis and dynamic mechanical analysis. It was found that the desired exfoliated nanocomposite structure was achieved when the OrgMMT loading was 1 and 2 wt%, whereas a partially exfoliated or intercalated nanocomposite was obtained for 3 wt% loading. All the nanocomposites were found to have improved thermal and mechanical properties as compared with virgin acrylated epoxidized soybean‐oil‐based polymer matrix. The nanocomposite containing 2 wt% OrgMMT clay was found to have the highest thermal stability and best dynamic mechanical performance. Copyright © 2010 Society of Chemical Industry     

High-performance implementation of in-network traffic pacing for small-buffer networks

Demands on data communication networks continue to drive the need for increasingly faster link speeds. Optical packet switching networks promise to provide data rates that are sufficiently high to satisfy the needs of the future Internet core network. However, a key technological problem with optical packet switching is the very small size of packet buffers that can be implemented in the optical domain. Existing protocols, for example the widely used Transmission Control Protocol (TCP), do not perform well in such small-buffer networks. To address this problem, we have proposed techniques for actively pacing traffic at edge networks to ensure that traffic bursts are reduced or eliminated and thus do not cause packet losses in routers with small buffers. We have also shown that this traffic pacing can improve the performance of conventional networks that use small buffers (e.g., to reduce the cost of buffer memory on routers). A key challenge in this context is to develop systems that can perform such packet pacing efficiently and at high data rates. In this paper, we present the design and prototype of a hardware implementation of our packet pacing technique. We discuss and evaluate design trade-offs and present performance results from an prototype implementation based on a NetFPGA fieldprogrammable gate array system. Our results show that traffic pacing can be implemented with few hardware resources and without reducing system throughput. Therefore, we believe that traffic pacing can be deployed widely to improve the operation of current and future networks.     

On-demand particle enrichment in a microfluidic channel by a locally controlled floating electrode

A flexible strategy for the on-demand control of the particle enrichment and positioning in a microfluidic channel is proposed and demonstrated by the use of a locally controlled floating metal electrode attached to the channel bottom wall. The channel is subjected to an axially acting global DC electric field, but the degree of charge polarization of the floating electrode is governed largely by a local control of the voltage applied to two micron-sized control electrodes (CEs) on either side of the floating electrode (FE). This strategy allows an independent tuning of the electrokinetic phenomena engendered by the floating electrode regardless of the global electric field across the channel, thus making the method for particle manipulation far more versatile and flexible. In contrast to a dielectric microchannel wall possessing a nearly uniform surface charge (or zeta potential), the patterned metal strip (floating electrode) is polarized under electric field resulting in a non-uniform distribution of the induced surface charge with a zero net surface charge, and accordingly induced-charge electro-osmotic (ICEO) flow. The ICEO flow can be regulated by the control electric field through tuning the magnitude and polarity of the voltage applied to the CEs, which in turn affects both the hydrodynamic field as well as the particle motion. By controlling the control electric field, on-demand control of the particle enrichment and its position inside a microfluidic channel has been experimentally demonstrated.     

太空生长掺Te—GaAs单晶的结构缺陷观测

本文用X射线、电子显微镜和电子束阴极荧光方法,对在太空中生长的掺Te-GaAs单晶材料的结构完整性进行了实验研究.在地面生长的掺Te-GaAs有明显的杂质条纹,而在太空生长的晶体杂质条纹消失;在太空和地面生长的交界处于空间材料一侧的中心部位,存在一个大约5μm宽的高完整区.远离中心部位,空间材料的完整性降低,出现了大量位错并伴有微缺陷.实验结果表明:在微重力条件下生长化合物半导体GaAs对在其中的杂质均匀分布有利.在太生长时出现的大量位错和微缺陷,并不是在生长时由于失重所致,而是在太空生长时温度失控所引起的.     

Determination of optimum hazelnut roasting conditions

The objective of this study was to test the hypothesis that the roasting conditions used for hazelnuts, such as the air temperature, air velocity and roasting time (independent variables), could be optimized by using Response Surface Methodology. Effects of independent variables on sensory and physical characteristics were determined. A consumer test was used to determine the acceptable samples. Very dark and very light roasted samples, corresponding to 165 °C, 3 m/s, 25 min and 125 °C, 1 m/s, 15 min process conditions, respectively, were unacceptable. Superimposed contour plots were used to determine the values of independent variables and these showed the process conditions where all product characteristics were acceptable to consumers. At low velocity (0.3 m/s), acceptable products were produced at about 165–179 °C for 20–25 min. When air velocity increased, air temperature shifted to lower temperatures. Samples roasted at 145 °C, 2 m/s, 28 min, 165 °C, 1 m/s, 25 min and 145 °C, 3.7 m/s, 20 min produced the most acceptable products. The sample roasted at 165 °C, 1 m/s, 25 min required the least air velocity and was the most economical in terms of energy consumed among the samples rated most acceptable by consumers.