液相连续制备挂式四氢双环戊二烯

挂式四氢双环戊二烯(exo-THDCPD)是重要的高密度液体烃类燃料。为提高exo-THDCPD的合成效率,研究了连续制备exo-THDCPD的新工艺,包括两个反应器(鼓泡式连续流加氢反应器和连续流异构化釜式反应器)的串联,即两个过程(Pd/C催化环戊二烯二聚体(DCPD)加氢制备桥式四氢双环戊二烯(endo-THDCPD)和Al Cl3催化endo-THDCPD异构合成exo-THDCPD)的串联。结果表明,液相连续制备exo-THDCPD的较佳工艺条件为:重时空速2.4 h-1,加氢压力0.1 MPa,氢气流速80 m L·min-1,DCPD浓度0.76 mol·L-1,加氢反应温度30℃,异构化反应温度70℃;DCPD转化率100%,exo-THDCPD收率92.5%。     

Mechanism and kinetic study for the intensification of two-step synthesis of a dolutegravir intermediate in microreactor

Multi-step reaction processes are frequently encountered in the synthesis of pharmaceuticals, separate study on each step however is easily neglected. Herein, we separately investigated two reaction steps for the synthesis of an intermediate (DTG-6) of an anti-HIV drug dolutegravir (DTG) in microreactors. The first step (i.e., deprotection of DTG-4) was optimized to achieve a high DTG-5 yield (i.e., 96.7%) in the microreactor after the parametric screening on the DTG-4 concentration, methanesulfonic acid loading, molar ratio of reaction components, and so forth. Reaction kinetics was revealed based on substantial experimental data and mechanism cognition. Validation experiments showed the accuracy of this reaction kinetics. After thoroughly understanding this deprotection step, we combined it with the following annelation step in a cascade microreactor system for the two-step synthesis of DTG-6 with a much higher yield even at a remarkably shorter residence time compared with literature reports, thus indicating efficient process intensification.     

AA3流动分析仪检测地表水总氰的可行性研究

总氰是一个重要的水质指标,该文旨在研究AA3流动分析检测总氰的稳定性与准确性。通过采用AA3流动分析测定了总氰标准物质、地表水样、加标水样,结果表明,AA3流动分析仪的测定结果稳定性高、准确性好。同时,将AA3法与国标法的测定结果进行比较显示,当样品浓度大于仪器检出限(0.000 5 mg/L)时,AA3法和国标法的结果没有明显差异。综上所述,AA3流动分析仪对总氰的测定具有高准确度和高精密度以及更低检出限等优点。     

A simple continuous-flow toxicity test system for microscopic life stages of aquatic organisms

This paper describes a flow-through toxicity testing system utilizing a new exposure chamber designed for microscopic organisms. Typically, flow-through testing is conducted with either a serial or proportional diluting system. While generally relying on gravity to drive water flow, as different amounts of toxicant and diluent are combined in glass or plexiglass mixing cells, they are almost always open to the surrounding atmosphere. In contrast, the system described here is based on a simple exposure design utilizing premixed stocks representing each exposure concentration. While the system is entirely closed to the surrounding atmosphere, for testing of volatile organic mixtures in addition to nonvolatile inorganic toxicants, the delivery manifold may be aerated for toxicants of low volatility and high BOD. The system incorporates flexible Teflon gas sampling bags for stock preparation and storage (thus avoiding need for a headspace), and digital unified-drive peristaltic pumps for controlled toxicant delivery. To reduce surface partitioning of toxicants, all system components are constructed of chemically inert materials (Teflon, glass and silicone).     

Miniaturized continuous-flow polymerase chain reaction microfluidic chip system

A miniaturized continuous-flow polymerase chain reaction (PCR) microfluidic chip system was developed to perform DNA amplification. This system consists of a 20-cycle continuous-flow PCR microfluidic chip, an electrical heating system and a miniature air pressure-vacuum pump. The chip was ablated with excimer laser direct-writing micromachining technique on a polymethyl methacrylate (PMMA) sheet. The ablated microchannel was inverse trapezoidal with a depth of 70 μm, top width of 200 μm and bottom width of 120 μm. Its surface roughness Ra was 1.42 μm after being treated with excimer laser polishing. The substrate sheet ablated with the microchannel was bonded with other cover sheets using hot-press bonding method to form a closed structure. The electrical heating system consisted of three groups of heating membranes, Pt100 sensors, copper blocks and PID temperature digital controllers. It could provide three distinct maintained temperature zones and a uniform temperature distribution in each zone. PCR amplification of a 170 base pair (bp) DNA fragment was carried out to validate the system's feasibility. The PCR temperatures were set as 94℃ for denaturation, 55℃ for primer annealing and 72℃ for extension. The flow rate in the microchannel was 40 nL/s and the total time for the completion of a 20-cycle amplification of 20 μL reagent was 15 min.     

采用流水式和半静态试验体系比较3,4-二氯苯胺对大型蚤的繁殖毒性

分别采用持续流水式系统和半静态系统为暴露途径,比较研究难溶化学品3,4-二氯苯胺对大型蚤繁殖影响的差异.结果表明,在半静态系统中3,4-二氯苯胺对母蚤繁殖、生长和生存的最低可观察质量浓度（LOEC）和最高无作用质量浓度（NOEC）分别为0.01、0.005 mg/L;在流水式系统中3,4-二氯苯胺对母蚤繁殖的LOEC和NOEC分别为0.02、0.01 mg/L,对生长和生存的LOEC和NOEC分别为0.01、0.005 mg/L.     

H2/空气CSTR双稳定状态及点火过程的基元反应模拟

利用基元反应机理数值模拟了H2／空气良好搅拌反应器(CSTR)系统的双稳定状态和点火过程．在入口温度较低时,系统在低流量和高流量时都存在一个熄火极限．在着火极限流量范围内,既存在一个高温稳定状态(着火状态),还存在一个略高于入口温度的低温稳定状态,具有双稳定状态．随着入口温度的增加,CSTR系统低流量的低温稳定状态会消失．在双稳定条件下,系统的最终状态取决于系统初始填充空气的温度．当该温度高于点火温度时,系统处于高温稳定态;低于点火温度时,系统则处于低温稳定态．点火温度与系统压力的关系为典型的“Z”型曲线．     

进水碳氮比对连续流双污泥系统氮磷去除的影响

采用连续流双污泥系统模拟污水处理中试试验,通过改变碳源投加量实现不同C/N比,探究连续流双污泥系统C/N比对污染物去除效果的影响及作用机制。结果表明:连续流双污泥系统在不同进水C/N下,均能取得稳定的脱氮除磷效果;随C/N比升高,反硝化作用增强,TN去除率相应升高,C/N比值为5、6时,平均去除率可达86%;C/N比对氨氮去除效果影响较小;C/N比对TP去除效果影响显著,C/N比值为3时TP去除率最高,平均去除率为93%,随C/N比增高去除率逐渐下降,C/N比值为6时TP平均去除率仅为61%。可见,连续流双污泥系统对进水C/N比偏低的生活污水有着更好的处理效果。     

利用反硝化抑制硫酸盐还原的连续流试验研究

为控制油田地面系统中硫酸盐还原菌产生硫化物造成设备腐蚀．采用连续流ABR反应器进行了反硝化抑制硫酸盐还原的研究，考察了反硝化抑制硫酸盐还原的影响因素和运行效果。结果表明，SO4^2-／NO3^-值和COD含量是影响反硝化抑制硫酸盐还原的最重要因子．SO4^2-／NO3^-值为1：1时抑制效果最佳，较低的COD含量有利于提高抑制效果，利用反硝化抑制硫酸盐还原必须在硝酸盐的有效作用区段内进行。氧化还原电位为-50～-150mV时．反硝化作用占优势地位；氧化还原电位为-300～-400mV时。硫酸盐还原反应占优势地位。     

A microcomputer-interfaced continuous flow toxicity test system

While continuous-flow tests for toxicity evaluation are preferable over static tests, their use has been limited due to problems associated with their operation. Fluctuations in toxicant concentrations during exposure periods requires frequent analyses and represent a drawback in conventional diluter systems. To reduce toxicant fluctuations and to maintain suitable water quality during long-term test periods, a low cost microcomputer-interfaced monitoring system (MIMS) was installed on a Benoit type serial diluter. The system monitored flow rates of test solutions and measured a number of water quality parameters.The MIMS system provided up-to-date information on whether the test was progressing well and indicated when diluter maintenance was needed. The MIMS interfaced diluter system performed well in long-term continuous-flow tests with minimal disruption and eliminated experimental failure.