合成甲醇工艺学(Ⅴ)

<正> 第五章粗甲醇精馏合成过程制得的祖甲醇产品中主要杂质是水、二甲醚及成分复杂的微量杂质,这些微量杂质有五十多种各种类别的含氧有机化合物,其总含量一般小于1.0wt％,主要是C_2～C_6醇类。正是这些微量的杂质影响精甲醇的质量,其中主要的是不饱和化合物,酮、羰基铁和氮化合物。粗甲醇色谱分析的数据列于表5.1。表中介绍了杂质能和水及甲醇生成共沸混合物的特性。     

TreePlus: interactive exploration of networks with enhanced tree layouts

Despite extensive research, it is still difficult to produce effective interactive layouts for large graphs. Dense layout and occlusion make food Webs, ontologies and social networks difficult to understand and interact with. We propose a new interactive visual analytics component called TreePlus that is based on a tree-style layout. TreePlus reveals the missing graph structure with visualization and interaction while maintaining good readability. To support exploration of the local structure of the graph and gathering of information from the extensive reading of labels, we use a guiding metaphor of "plant a seed and watch it grow." It allows users to start with a node and expand the graph as needed, which complements the classic overview techniques that can be effective at (but often limited to) revealing clusters. We describe our design goals, describe the interface and report on a controlled user study with 28 participants comparing TreePlus with a traditional graph interface for six tasks. In general, the advantage of TreePlus over the traditional interface increased as the density of the displayed data increased. Participants also reported higher levels of confidence in their answers with TreePlus and most of them preferred TreePlus     

Ligands and receptors mediating signal transduction in sea urchin spermatozoa

Sea urchins have long been a model system for the study of fertilization. Much has been learned about how sea urchin sperm locate and fertilize the egg. Sperm and eggs are spawned simultaneously into the surrounding seawater. Sperm signaling pathways lead to downstream events that ensure fertilization. Upon spawning, sperm must acquire motility and then they must swim towards or respond to the egg in some way. Finally, they must undergo a terminal exocytotic event known as the acrosome reaction that allows the sperm to bind to the vitelline layer of the egg and then to fuse with the egg plasma membrane. Motility is stimulated by exposure to seawater, while later events are orchestrated by factors from the egg. The sperm signaling pathways are exquisitely tuned to bring the sperm to the egg, bind, and fuse the two cells as quickly as possible.     

合成甲醇工艺学(Ⅰ)

<正> 概论甲醇是化学工业的重要产品之一.1661年,波义耳首先在木材干馏产品中发现了甲醇.1834年,杜马司和彼利哥特制取了纯净的甲醇,并确立了它的分子式.1923年,德国首次用一氧化碳和氢在锌-铬催化剂上压力为25～35MPa温度为320～380℃合成甲醇成功,并较快地得到发展.六十年代,英国用含铜的低温催化剂合成甲醇成功,把甲醇生产提高到新的技术水平.目前,新建的用一氧化碳和氢合成甲醇的工厂都使用低温催化剂,     

Molecular detection of meat animal species targeting MT 12S rRNA gene

The efficacy of PCR-RFLP analysis of mt 12S rRNA gene in identification of animal species from meat samples of known and unknown origin and adulterated meat samples was evaluated. In PCR, all the samples generated an amplicon of 456 bp. Restriction enzyme digestion of the PCR product with AluI, HhaI, BspTI and ApoI revealed characteristic RFLP patterns. Of the samples of unknown origin few were identified as cattle, few as buffalo and some were admixtures of two, suggesting adulteration. The RFLP pattern of one did not match any of species included in the study, which on sequencing was confirmed as camel meat. Application of this technique on adulterated meat samples could detect both animal species in proportion of 50:50 and 75:25 (except in case of goat+cattle). The technique however could not detect any of the two species when proportion of mixture was 90:10 (except in case of cattle+buffalo).     

Natural radionuclides in zircon and related radiological impacts in mineral separation plants

The activity concentration of uranium and thorium present in zircon obtained from mineral sand industries are presented. External gamma radiation levels and inhalation of airborne dust are found to be the significant routes of radiation exposure to occupational workers. The annual average dose attributed to zircon processing is estimated to be 2.3 mSv in the plants under study. This paper presents the results of external gamma measurements, estimation of airborne radioactivity in zircon process locations and radon and thoron in the occupational environment of two mineral separation plants in India. Analyses of the solid wastes and liquid effluent generated and resultant environmental impacts are indicated.