管内插偏重式螺旋轮自转及对流传热特性

针对换热管内污垢在线清洗的难题,提出了管内插偏重式螺旋轮自动防除垢技术。理论分析了螺旋轮获得的自转动力矩,并通过实验研究其自转特性;进一步对管内插偏重式螺旋轮的对流传热特性进行实验研究,对比分析偏重因素对传热强化性能的影响。结果表明:在一正一反交替连接时螺旋轮获得的自转速度最大,更有利于螺旋轮的旋转;传热温差为7℃时,管内插螺旋轮的总传热系数比内插螺旋线、内插扭带时分别提高22.2%和12%;传热温差为15℃时,内插不同偏重式螺旋轮的总传热系数与光管相比分别提高89%和112%,与内插普通螺旋轮的传热系数相比分别提高12%和25%,但相应的沿程阻力损失随之增加。考虑传热和阻力两方面因素,对上述管内插物的综合性能进行比较,结果显示内插偏重式螺旋轮的综合性能最好。     

组氨酸修饰的硅纳米线阵列对免疫球蛋白的选择吸附

首先利用化学腐蚀的方法,制备了具有纳米拓扑结构的硅纳米线阵列,然后利用一系列化学反应将组氨酸接枝在硅纳米线阵列表面。扫描电子显微镜(SEM)、紫外光谱、水接触角对硅纳米线进行了表征。酶联免疫吸附试验(ELISA)结果表明表面固定组氨酸的硅纳米线可选择性吸附免疫球蛋白IgG。     

试剂产业创新成功商业模式的探讨

在梳理了商业模式本质与要素的基础上,针对目前试剂行业的发展现状和商业模式,以及国药集团化学试剂有限公司在试剂产业化过程中成功商业模式的建立进行了讨论,并结合开放式创新背景下商业模式变革的必然性,对存在的问题提出了改进建议和举措.     

Modeling and On-line Measurement of Drying Stress of Pinus massoniana Board

A drying stress model was established by considering that the total shrinkage of wood is the sum of free shrinkage, instantaneous strain, viscoelastic strain, and mechanosorptive strain. From the stress model, the stress can be calculated once the actual wood shrinkage and moisture content gradient are known. Based on this theory, on-line measurement of the drying stress has been realized by measuring the moisture content (MC) gradient between the surface and the core layers, and the actual shrinkage of the board for Pinus massoniana.

A sensor for measuring wood shrinkage was developed based on electric resistance and strain relationship in a selected element material within the sensor. A resistance type of MC sensor was used for the MC gradient measurement. These sensors are reliable and can meet the requirement of the measurements in practical drying. The technique reported in this article for detecting drying stress from the on-line measurements of board shrinkage and MC gradient can be applied to develop optimized drying schedule in commercial drying.     

COMPARISON BETWEEN THREE-PHASE EXTRACTION SYSTEM OF TBP-KEROSENE/HClO4-H2O AND TWO-PHASE EXTRACTION SYSTEM OF TBP/HC104-H2O *

ABSTRACT

Three-phase extraction system of TBP-kerosene / HClO₄-H₂O has been studied and compared with two-phase system of TBP / HClO₄-H₂O. The results indicate that the composition of the middle phase and its change with the increasing aqueous acidity in the three-phase system are almost the same as that of the organic phase in two-phase system. The extraction in high acidity can be explained by the solubilization of acid and water in the aggregates formed by amphiphilic extracted complexes.     

Observations on Finger-like Crack Growth at a Urethane Acrylate/Glass Interface

Interfacial crack growth behavior along a urethane acrylate/glass interface is characterized by the development of finger-like perturbations along the advancing crack front. The finger-like perturbations grow from a slightly irregular crack front until they reach a steady-state where the velocity of the finger tips equals the velocity of the finger valleys. Once the fingers reached steady-state, the crack velocity was dependent on the applied strain energy release rate via a power law relationship where the exponent was independent of test humidity; however, the multiplicative constant A decreased by an order of magnitude from 80 to 15% RH. The spacing of the fingers was found to be independent of the crack′s velocity and the relative humidity of the environment.     

Electrospun ZnO Nanofibers‐Based Ultraviolet Detector with High Responsivity

In this report, a metal–semiconductor–metal (MSM) ultraviolet photodetector based on ZnO nanofiber film with Au electrodes was demonstrated. The ZnO nanofibers were synthesized via effective electrospinning process and characterized by means of XRD, SEM, XPS, and UV–visible absorption spectra. At 5 V bias, the dark current of the device was 17.8 nA. Under the irradiation of 260 nm ultraviolet light, the photocurrent could reach 11.5 μA and a high responsivity of 790 A/W was achieved due to the large internal gain. The mechanism of the high internal photoconductive gain was discussed in the article. The experiment presented a general and simple approach to integrate electrospun nanomaterials into photodevices directly.     

Low‐Temperature Sintering and Electric Properties of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 Ferroelectric Ceramics with CuO Additive

The low‐temperature sintering and electric properties of Pb_0.99(Zr_0.95Ti_0.05)_0.98Nb_0.02O₃ (PZTN 95/5) ferroelectric ceramics with CuO addition was investigated. The CuO addition significantly promoted the densification and reduced the sintering temperature of PZTN 95/5 ceramics by more than 200°C. The 0.2 wt% CuO‐added sample sintered at 1150°C exhibited the optimum relative density of 96.7% and excellent electric properties with values of P_r = 37.80 μC/cm², T_C = 223°C, ε_r = 329, and tan δ = 0.016, which were superior to that of PZTN 95/5 ceramics sintered at 1350°C.     

PARTITION COEFFICIENTS OF SOME ANTIBIOTICS,PEPTIDES AND AMINO ACIDS IN LIQUID-LIQUID PARTITIONING OF THE ACETONITRILE-WATER SYSTEM AT SUBZERO TEMPERATURES

Liquid-liquid equilibrium (LLE) occurs at a subzero temperature for the acetonitrile-water binary system. When the equilibrium temperature is below its LLE critical temperature of ? 1.32°C, the top phase is acetonitrile-rich and the bottom phase water-rich. It was observed that a human growth hormone analog with 191 amino acids partitioned exclusively into the bottom phase and its bioactivity was retained. This suggests that the liquid-liquid partition system can be used for bioseparations. The new system gives a different selectivity and the low temperature environment offers better stabilities for biomolecules compared to conventional solvent extraction systems. This work presented the partition coefficients of some biomolecules including trypsin, thyroglobulin, transferrin, ribonuclease A; L-phenylalanine, L-tryptophan; val-ala-ala-phe, phe-gly-gly-phe; erythromycin, chloramphenicol, vancomycin, spiramycin, gramicidin D, cycloheximide, fusidic acid, antimycin and tetracycline. Temperature and pH effects, as well as partition mechanisms were probed.     

Preparation and evaluation of particleboard bonded with a soy flour-based adhesive with a new curing agent

Urea-formaldehyde (UF) resin is one of the most commonly used wood adhesives for making particleboards. However, UF emits carcinogenic formaldehyde and is derived from nonrenewable petrochemicals. In this study, a new formaldehyde-free wood adhesive that is based on soy flour and a renewable material-based curing agent (CA) were prepared and evaluated for the preparation of M-2 grade particleboards. The new CA was derived from ammonia and epichlorohydrin that can be derived from renewable glycerol. The composition of the adhesive was soy flour/sodium hydroxide/CA at a dry weight ratio of 9/0.3/1.0. The modulus of rupture, modulus of elasticity, and internal bond strength met the minimum industrial requirements of M-2 particleboards using the following variables: hot-press temperature of 190?°C, hot-press time of 240?s, the adhesive usage of the face particles of 12?wt.%, the adhesive usage of the core particles of 10?wt.%, and the target particleboard density of 0.80?g/cm³.