The mechanism of color reversion in soybean salad oil

An enzymatic reaction might be the major cause of color reversion in soybean oil. During the soybean flaking process, enzymatic reactions take place to convertγ-tocopherol to 5-(tocopheryloxy)-γ-tocopherol (γ-TED), and then further convertγ-TED to the precursors which are the cause of color reversion. The variations ofγ-tocopherol andγ-TED contents in soybean oil are accompanied by an inverse change in the precursors’ concentration. Therefore, the contents ofγ-tocopherol orγ-TED in crude soybean oil could be used as an index for predicting the color quality (color reversion) of soybean salad oil. Almost all the precursors (such as tocored) were converted to color-reverted substances under catalysis after bleaching treatment, and they were converted back to the precursors during deodorization. Those precursors might be gradually reconverted into the color reverted substances during storage to cause the color reversion in soybean salad oil.     

Properties of recycled high density polyethylene from milk bottles

The effect of virgin, high-density polyethylene (HDPE)/recycled HDPE composition on the physical properties of the blends was investigated. The recycled HDPE was obtained from a postconsumer cycle of milk bottles. It was found that elongation at break was the mechanical property mostly affected by the content of recycled HDPE. Overall, however, the recycled HDPE from milk bottles was found to be a material with useful properties not largely different from those of virgin resin and thus could be used, at an appropriate concentration in virgin HDPE, for different applications.     

Moisture Distribution and Dewatering Efficiency for Wet Materials

This review paper summarizes current research efforts toward a comprehensive view of wet material dewatering, considering the binding energy as the strength to hold water, and rupture energy given to remove moisture from materials.     

FCS-DCS两种控制系统比较

当前现场总线控制系统(FCS)是控制领域中的热点,是在集散控制系统(DCS)的基础上产生的,二者是继承和发展的关系。DCS已走过了近30年的历程,广泛应用于化工、石油、电力、水泥等工业过程,基本上满足了大、中、小控制工程的需求。传统的DCS系统由各种工作站通过     

A method for transformation of engineering bill of materials to maintenance bill of materials

In order to solve the transformation problem of Bill of Materials (BOM) from engineering BOM to maintenance BOM for Maintenance, Repair and Overhaul (MRO) systems, a formal transformation model of BOM view is proposed. In this model, the intermediate component, inherited component, virtual component are defined in the specific maintenance management domain, and the transformation process from engineering BOM to maintenance BOM is discussed through feature recognition methods and rules. The proposed transformation model has been developed and deployed in an MRO system for a steel manufacturing enterprise.     

应用免疫斑点法检测不同工艺灭活的乙肝血源疫苗中的前S_1和S_2蛋白

作者应用前 S_1、前 S_2和 HBsAg/a 单克隆抗体,用免疫斑点法(Immuno-spot)检测同一批的乙肝表面抗原分别经加热灭活和三步化学灭活后的前 S_1和前 S_2蛋白保留情况,比较了两种工艺对前 S_1和前 S_2蛋白的影响。结果表明;加热灭活可保留前 S_1和前 S_2蛋白,三步化学灭活使前 S_1和前 S_2蛋白丢失,从抗原组成上看,加热灭活后的抗原更接近自然抗原。首次报告了含有前 S_1蛋白的乙肝疫苗,并对前 S_1和前 S_2蛋白在乙肝血源疫苗中的可能作用进行了讨论。     

Thermotropic polyester carbonates. III. Thermotropic polyester carbonates as self-reinforced plastics

Thermotropic polyester carbonates derived from t-butylhydroquinone, methylhydroquinone, diphenyl terephthalate, and diphenyl carbonate in the molar ratio of 50 : 50 : 55 : 45; 50 : 50 : 57.5 : 5 : 42.5 and 50 : 50 : 60 : 40 can be injection molded successfully from temperatures 10°C below melting to 30–40°C above melting. Normally the best molding temperatures are 10–20°C above melting. If the molding conditions are controlled properly, tensile strengths as high as 1.8 × 10⁴ psi, tensile moduli as high as 7.4 × 10⁵ psi, and flex moduli as high as 1.1 × 10⁶ psi can be obtained.     

Graft polymerization of vinyl acetate onto granular starch: Comparison on the potassium persulfate and ceric ammonium nitrate initiated system

This work was undertaken to discuss in depth the vital differences in the morphological development during synthesis, and properties of starch‐g‐poly‐(vinyl acetate) copolymers using two different initiators, potassium persulfate (KPS) and ceric ammonium nitrate (CAN). KPS‐initiated system gave relatively low values of grafting ratio and grafting efficiency, indicating a great tendency for the formation of poly(vinyl acetate) homopolymer (PVAc). Yet, higher values were seen for the CAN‐initiated system. Transmission electron microscope observations indicated a relatively broad distribution of latex particles for the KPS‐initiated system. The surface potential of latex particles was about ?3.5 mV, which turned out to be insufficient to maintain stability of latex particles. On the other hand, a uniform particle size distribution was found for the CAN‐initiated system, as the surface potential of latex particles was 21.5 mV. Moreover, radicals on starch molecules were generated directly through a redox reaction with positively charged ceric ion. The hydrophobic PVAc chains were thus grafted on starch, resulting in an amphiphilic graft copolymer, which provides a sufficient stabilization degree as a role of surfactant to render a relatively uniform distribution of latex particles. The synthesized starch‐g‐poly(vinyl acetate) copolymers were further converted to starch‐g‐poly(vinyl alcohol) through saponification, which were subjected to evaluations regarding the biodegradation and cell culture capability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3017–3027, 2006     

Design and control of reactive distillation for ethyl and isopropyl acetates production with azeotropic feeds

Reactive distillations for the production of ethyl acetate (EtAc) and isopropyl acetate (IPAc) are classified as the type-II process where the first column consists of a reactive zone and a rectifying section followed by a stripper [Tang et al., 2005. Design of reactive distillations for acetic acid esterification with different alcohols. A.I.Ch.E. Journal 51, 1683-1699]. Instead of using pure alcohols and acetic acid as reactants, this paper studies the effects of reactant purity on the design and control of reactive distillation. This offers significant economical incentives (by reducing raw materials costs), because ethanol forms an azeotrope with water at 90 mol% and isopropanol/water has an azeotrope at 68%. The purities of the acid is set to 95% for acetic acid (industrial grade), 87% for ethanol, and 65% for isopropanol. The results show that the total annual costs (TAC) increase by a factor of 5% for EtAc and 8% for IPAc production using reactive distillation. Next, the operability of the reactive distillations with azeotrope feeds is explored. Three disturbances, feed flow, acid feed purity, and alcohol feed composition, are introduced to assess control performance using dual-temperature control and one-temperature-one-composition control. Simulation results indicate good control performance can be achieved for reactive distillation with azeotropic feeds.     

过渡金属对Ru/海泡石催化剂加氢性能及表面性质的影响

用浸渍法制备了一系列含不同助剂Mo、Co、Mn、Cu、Zr等的Ru/海泡石催化剂，以CO₂及苯加氢为探针反应，以TPD和CS₂中毒为手段研究了助剂对Ru/海泡石催化剂加氢、反应物吸附及活化性能的影响。结果表明，助剂的加入显著地影响Ru/海泡石催化剂的催化活性，且随着反应分子的加大，这种影响随之增大；助剂对催化反应中反应物的吸附、活化过程的影响是其影响催化活性的重要原因。另外，结果还表明，助剂的加入还调整了Ru/海泡石催化剂的表面性能，但并没有改变活性中心的类型。