Recovery of organic acids from fermentation broths

Rising concerns over the use of fossil resources have generated renewed interest in the production of commodity chemicals via fermentation. Organic acids are a particularly attractive target because their functionality enables downstream catalytic upgrading to a variety of compounds. In this article, we survey how common technical issues are addressed in the recovery schemes for several organic acids. We present results for the recovery of acetate using a new method based on amine complexation. Our reactive separation scheme produces a high-purity product, is energy efficient, and avoids the coproduction of a waste salt coproduct, all prerequisites for a large-scale production process.     

极谱分析法连续测定痕量铅和镉

研究了 Pb2 + 和 Cd2 + 与 KCl-酒石酸钠 -三乙醇胺 -明胶体系的二次导数极谱波。在 p H=4 .5的 HAc-Na Ac介质中 ,Pb2 + 和 Cd2 + 分别于 - 0 .4 6 V和 - 0 .6 4V电位处产生一良好的极谱波。峰电流与 Pb2 + 和Cd2 + 的浓度分别在 1× 10 -5— 3× 10 -1g· L-1和 5× 10 -5— 6× 10 -3 g· L-1范围内呈线性关系。 Pb2 + 和Cd2 +的检出限分别为 1× 10 -7g·L-1和 5× 10 -7g·L-1。本法准确、简便、快速、选择性高。已直接用于饮料中铅和镉的连续测定 ,同时也对酒及面粉样品进行了测定 ,回收率分别为 99.9%— 10 0 .1%和 97.0 %—10 4 .8%。     

ASYMPTOTIC BEHAVIOR OF BOOTSTRAP SPECTRAL WINDOW ESTIMATION

ThisprojectissupportedbytheNationalNaturalScienceFoundationofChina.1.IntroductionLetX~{X(t);t=0,FI,12,'}beazerthmeantunitvariancestationaryGaussianprocess,theautocovariancefunction7(u)=EX(n u)X(n)satisfySupposethatthespectraldensityfunctionisf(A)andspectraldistributionfunctionisF(A)oftheprocessX,wherewerestrictAwithin11(if=[--x,7]).Fromtheassumptionsabove,wecaneasilyseethatthef(A)isjustaprobabilitydensityfunction,andF(A)isaprobabilitydistributionfunction.LetX(1),'tX(n)betheobserv…     

分位点随机配序抽样

该文针对统计计算中的某些随机模拟问题提出了分位点随机配序抽样法.该方法是由抽样分布的分位点和伪随机序复合构成的,适用于固定区域上多重积分的计算及随机变量的抽样.该文通过几个典型实例说明该方法在具体问题中的应用,并验证了该方法的计算精度.     

激光涂层零件的多冲碰撞形变效应与分析

报道了多冲碰撞载荷下激光涂层零件塑性变形现象。利用坐标网格法、显微分析法等分析了激光涂层零件的多碰累积变形现象和规律。这种塑性变形在常温即可发生,且具有低应力和累积特性。变形发生在涂层表面及以下一段区域内,并由大到小呈梯度变化。碰撞能量驱动、冲击温升效应、晶界滑动与迁移、亚结构的形成与孪晶等,是引起多碰累积变形的可能原因。     

分散有ZnS:Mn2+纳米超微粒的有机薄膜的制备和光学性质

近年来,半导体超微粒的合成及光物理性质研究已成为活跃的领域.由于量子尺寸效应引起的量子点能级结构的变化及其光学性质已经作了大量研究[1-4].1993年,Bhar-gava首次报导了化学反应合成的ZnS Mn超微粒的光学性质[5],掺杂半导体纳米材料的出现,为纳米科学的研究开辟了新的领域.     

空间有理参数多项式曲线的整数级绘制算法

讨论了空间有理曲线中心投影后导数上界的估计，基于曲线各阶差分的递推计算，给出了空间有理参数多项式曲线的快速绘制算法．算法只用到整数的加减法，效率高．     

数字电视条件接收系统的研究

条件接收系统是数字电视的关键部分,也是密码学的一种应用.从密码学的角度及信息安全的角度对数字电视条件接收系统进行了分析.     

Simulating Single Event Transients in VDSM ICs for Ground Level Radiation

This work considers a SET (single event transient) fault simulation technique to evaluate the probability that a transient pulse, born in the combinational logic, may be latched in a storage cell. Fault injection procedures and a fast fault simulation algorithm for transient faults were implemented around an event driven simulator. A statistical analysis was implemented to organize data sampled from simulations. The benchmarks show that the proposed algorithm is capable of injecting and simulating a large number of transient faults in complex designs. Also specific optimizations have been carried out, thus greatly reducing the simulation time compared to a sequential fault simulation approach.