Cl原子与CH_3COCH_3抽提反应机理的密度泛函理论研究

QCISD(T)/6-311++G(d,p)//B3LYP/6-31G(d,p)双理论方法研究了Cl原子与CH3COCH3的抽提反应过程。该反应包括两个反应通道:即Cl原子从CH3COCH3上直接抽氢(R1)和抽取CH3基团(R2)。在B3LYP/6-31G(d,p)水平上优化了反应物、产物、过渡态的几何构型,并作了最小能量路径分析,计算了反应的焓值和反应势垒,结果表明R1势垒比R2势垒低109.48 kJ/mol,说明反应R1是主反应通道。     

C_9 FK的表面活性测定

用吊片法和自制改进的最大泡压法分别测定了全氟庚氧基全氟亚乙基磺酸钾(C9FK)溶液的平衡和动态表面张力,计算得出该种表面活性剂形成胶束的标准热力学函数△Hmθ、△Smθ、△Gmθ分别为16．98 kJ／mol、218．29 J／mol·K、-48．22 kJ／mol。结合Word-Tordai方程,计算得到在不同条件下的表观扩散系数Da和吸附势垒Ea。实验证明,增大表面活性剂的浓度、降低温度、以及无机盐(NaCl)的加入都会使扩散系数减小,吸附势垒增大,从而不利于吸附的进行。当表面活性剂的浓度小于等于1×10-6 mol/L时,该体系属于扩散控制模型,而浓度大于 1×10-6 mol/L时,在吸附初期(t→O)属于扩散控制,后期均属于混合控制模型。     

红外光谱中定量关系的研究:以极化效应指数对碳氧双键振动频率的分子建模与定量预测

系统研究发现 ,烷基化效应指数PEI(R)可用于碳氧双键即羰基 (>C =0 )振动频率 (vCO )的分子建模和定量预测。其定量构谱关系经线性回归得出 :v =a bPEI(a>0 ,b <0 )。结果表明 ,烷基极化效应使羰基频率降低。     

建筑涂料

1223一35页一FR1998/7637(1998.6.17);正CC08J3/03 本发明的水乳液组成如下:(l)含有)l个T或Q结构单元的平均分子通式为M户hTcQd(o一二R)。(M=R’RZR3sio.二:o二R4R5sioZ,2:T=5103二;Q=510二;R’一6=烷基、链烯基、氨烷基、芳基、芳烷基、烷芳基、芳芳基;R=H或烷基;a=0一0 .5:b=0一0.95;e=0一0.9:d二0一0.8:e=0.05一2:a b e d=l)的)l种树脂;(2)由(a)与(b)形成的反应产物,其中(a)为>l种NH,、多官能度芳胺和多官能度脂肪胺,(b)为)l种梭酸或酸醉,有时还可有)l种水溶性金属交联剂;以及(3)》l种非离子型、阴离子塑和两性表面活性剂。例…     

碳的雨贡纽状态方程及动压合成金刚石机理——动压合成金刚石之二

动压法已经成为纳米金刚石和多晶金刚石的主要合成方法,按照方法的不同又可以分成爆轰法、爆炸法和激光法等多种方法。文章论述了碳的雨贡纽状态方程和碳的高压相图。分析了爆轰法、爆炸法和激光法等几种不同方法合成金刚石的原理。估算出石墨直接转化金刚石所必须越过的势垒值为8.565×104J·mol-1,其激光源的功率密度不应低于2.534×105 W·cm-2。     

基于Sine-Gordon方程的三角形势垒层平面约瑟夫森结仿真

通过数值计算的方法求解Sine-Gordon方程，模拟研究了势垒层平面为三角形形状的约瑟夫森结在磁场下的超导层间相位差动态分布情况，以及结电流电压特性和超导电流（约瑟夫森隧道电流）分布特性。文中给出了详细的仿真模型构建过程、初始条件设置，以及主要伪代码。仿真结果可以得出，在平行于结势垒层平面磁场下，约瑟夫森结边界尖角位置相比于长边位置更易于结中约瑟夫森磁通的流动进出。     

三氧化钨陶瓷的压敏特性和机理

采用传统电子陶瓷烧结工艺,制备了无掺杂物的三氧化钨(WO3)陶瓷。分析了陶瓷样品经淬火和不同气氛下处理后的微结构和压敏电学特性。研究表明:陶瓷冷却过程中在氧吸附的作用下,WO3陶瓷晶粒表面呈现氧元素富集。分析认为,晶粒表面吸附的氧与晶粒内的电子作用,在晶粒表面形成界面态,并进一步在晶界形成Schottky势垒,这可能是WO3陶瓷压敏行为的起源。根据实验结果,提出了一种修正的晶界Schottky势垒模型,解释了WO3陶瓷的压敏行为。     

十二烷基硫酸钠/正丁醇/正庚烷/水微乳液性质研究

25℃时,绘制十二烷基硫酸钠(SDS)/正丁醇/正庚烷/水体系在不同R值(水和SDS的摩尔比)时的相图,得出该体系能形成W/O微乳液的配比为:正丁醇的质量分数在25%~60%,正庚烷的质量分数在0~80%。该体系在室温下能够形成较大范围的W/O单相微乳液区,R值对微乳区的面积和所在的位置无太大的影响。采用电导率曲线讨论了加水稀释过程中,体系由W/O型→双连续型→棒状液晶→层状液晶→双连续型→O/W型的微观结构转变。采用稀释法求得其W/O型微乳液体系的结构参数,结果表明:体系的水内核半径Rw在讨论的范围内随VH2O、R值的增加而增大。含水量增加,自由能-ΔGcO→i降低,对微乳液体系的稳定不利;含水量越低,越有利于微乳液的形成和稳定。     

调节阀应用问答(六)

31、为什么调节阀不能在小开度工作? 先分析一下调节阀在小开度的工作状况。从阻力上看,ξ_i=ξC/C_i,阀关闭时C_i→0,则ξ_i→∞。阀一旦打开,ξ_i急剧下降,见图29—1。从速度上看,阀关闭时可认为     

盐酸曲马多缓释片的制备及其在健康人体内的药动学研究

制备了曲马多缓释片（100mg／片）,以缓释度为指标筛选出了曲马多缓释片的处方,并对该处方缓释片与市售同品种对照进行了人体单剂量及多剂量随机交叉给药药动学研究。用高效液相荧光色谱法测定了血浆中的药物浓度。单剂量口服自制缓释片的药动力学参数Tmax、Cmax、AUC0→∞分别为4．6±1．4h、287．83±53．83ng／mL、4487．92ng／mL·h。多剂量口服自制缓释片的药动力学参数（Tmax、Cssmax、AUC0→τT分别为3．0±0．7h、397．46±117．05ng／mL、5161．14±1774．92ng／mL·h。并且考察了该制剂的体外释放度,结果表明,该药体外释放速度平稳。     

Effects of CMAS penetration on the delamination cracks in EB-PVD thermal barrier coatings with curved interface

During the high-temperature operation of electron beam physical vapor deposited (EB-PVD) thermal barrier coating (TBC), the penetration of environmental calcium-magnesium-alumina-silicate (CMAS) compositions into the ceramic top-coat would affect the growth of delamination cracks. In this work, the effects of CMAS penetration on the delamination cracks in EB-PVD TBC with curved interface are investigated by finite element analysis. In the numerical model, the curved interface evolves as the cyclic displacement instability of the thermally grown oxide (TGO) layer. The penetration of CMAS into the columnar gaps of EB-PVD TBC mainly increases the in-plane modulus of TC layer. It is demonstrated that, with the increase of in-plane modulus in an intact TC, the level of tensile stress, which mainly occurs in the region above the curved interface and responsible for initiating the delamination cracks, presents a decrease; meanwhile, the level of shear stress, which mainly occurs in the region at the periphery of the curved zone to drive the delamination crack when it propagates into this region, presents a increase. Furthermore, the calculation of the strain energy release rate shows that, for the crack located above the curved interface, the increase of in-plane modulus in TC layer can prevent the accumulation of strain energy release rate, and therefore make it more difficult for delamination initiation. However, once the crack propagates into the flat periphery, CMAS penetration would begin to enhance its growth.     

Formation of Potential Barrier Related to Grain-Boundary Character in Semiconducting Barium Titanate

Resistance–temperature ( R – T ) characteristics were measured directly at single-grain boundaries in 0.1-mol%-niobium-doped barium titanate bicrystals that had been fabricated from polycrystalline sinters, to determine a geometrical grain-boundary character dependence of the positive temperature coefficient of resistivity (PTCR) effect. Both random boundaries and low-Σ boundaries exhibit a similar grain-boundary character dependence of the PTCR effect through a simple geometrical analysis, using the coincidence of reciprocal lattice points. Differences of the R – T characteristics in individual boundaries have been explained in terms of the formation of a potential barrier that is associated with the oxidation of grain boundaries during cooling, after sintering or annealing. The grain-boundary character is likely to affect the diffusivity of O²⁻ ions and, hence, is crucial to the formation of the potential barrier.     

镀层中基体金属扩散系数的测定

铜在防渗铜镀层中的扩散系统是评价镀层防渗铜能力的重要参数。采用电子显微探针法,“俣野”数值方法推导出扩散系数。并分析了铜在柱状和块状镍镀层中的扩散系数。     

微波辅助萃取过程中的分子扩散系数

建立了微波萃取虎杖中白藜芦醇过程中的分子扩散势垒模型;结合粘度理论建立了分子扩散系数与活化能之间的关系;利用活化能的概念和微波吸收功率密度表达式得到微波作用下的扩散系数表达式。从表达式可以看出,微波作用下的扩散系数与目标萃取物质的密度、微波频率及萃取温度有关,与未加微波的情况比较扩散系数明显增大。在微波辅助萃取有效成分过程中,若萃取温度较高,应选择频率较高的微波进行萃取,以最大限度提高扩散系数;对可能发生热失控现象的物质进行提取时,萃取温度应选择在临界温度附近,此时扩散系数较大。     

Generalized solutions for a dead-end duct having a permeable barrier

This paper presents an analytical method for calculating the flow and pressure in A dead-end duct which has a perforated, porous barrier and an auxiliary fan or an obstacle at the end of the duct. The solutions involve two infinite series which can be applied to a general class of differential equations. It is shown that the duct length may be bounded if the barrier is porous only. No such bound exists if there are holes in the barrier. There is a minimum in the flowrate through the duct when there is a fan at the dead end. No such minimum exists when there is an obstacle     

Evaluation of heat transfer coefficient in gas-solid fluidized beds using cluster-based approach

The concept of temperature penetration depth is used to investigate the heat transfer behavior near the wall of fluidized beds, according to the cluster-based approach. The process of heat transfer through clusters which exist adjacent to the wall was viewed in context of partial and total heat penetration. In the case of partial heat penetration, the heat flux applied to the wall side of the clusters has not reached its bed-side, while in the case of total heat penetration the heat flux has completely crossed the cluster, and the temperature of its bed-side would differ from the bed temperature. Based on the heat balance equation inside the cluster, two different expressions were derived for heat transfer coefficient for each penetration period. The predictions of the proposed model are in close agreement with experimental values and to some extent better than existing models.     

聚丙烯酰胺改良土-膨润土的渗透性及对苯酚的吸附

为提高土-膨润土(SB)隔离屏障的渗透性及其对苯酚的吸附效果,制备一种聚丙烯酰胺改良土-膨润土(PSB)。研究聚丙烯酰胺掺量、苯酚浓度、干湿作用、冻融作用对PSB隔离屏障渗透系数的影响及对苯酚的吸附效果,并从微观层次揭示其作用机理。结果表明:苯酚浓度对PSB隔离屏障渗透系数没有影响;干湿作用下PSB隔离屏障渗透系数增加但仍保持在同一个数量级,而冻融作用下隔离屏障渗透系数增大1~2个数量级;聚丙烯酰胺可使干湿、冻融作用下隔离屏障的渗透系数有所降低,即可有效抑制干湿、冻融的破坏作用;掺加0.7%(质量分数)聚丙烯酰胺的PSB隔离屏障对苯酚的吸附率可达69%以上,相比SB隔离屏障吸附率约提高50%,且随着苯酚污染液浓度增加,吸附率逐渐提高。该研究可为苯酚污染的隔离与封闭提供理论依据与参数支持。     

Film and penetration theories for a first-order reaction in exothermic gas absorption

Film and penetration models for simultaneous heat and mass transfer are developed for the absorption of gas with a first-order chemical reaction in the liquid phase with temperature-dependent solubility and reaction rate coefficient. These two models represent two extreme conditions of interfacial temperature rise and gas solubility and they are compared with some previous models (Allan and Mann, 1979; Asai et al., 1985). The approximate analytical expressions of the penetration model of Asai et al. (1985) are in good agreement with the numerical results of this work. The results reveal that under many practical circumstances the gas-liquid interfacial temperature may be several degrees Kelvin higher than the bulk liquid temperature. The degree of deviation of the enhancement factor from its isothermal value at the bulk liquid temperature depends on the degree of difference of a certain dimensionless activation energy group from zero, which confirms the previous finding of Asai et al. (1985).     

氧化石墨烯改性水泥砂浆抗氯离子渗透性能

采用快速电通量法及长期氯盐浸泡试验,研究了氧化石墨烯(GO)改性水泥砂浆的抗氯离子渗透性能,分析了电通量与表观氯离子扩散系数之间的关系,并通过扫描电镜(SEM)分析了其微观结构。结果表明:掺入适量的GO能够提升水泥砂浆的抗氯离子渗透性能,当掺量为0.06%(质量分数)时最显著,与无GO的对照组相比,水泥砂浆的电通量和氯离子侵蚀深度分别降低了34.5%和27.2%;长期氯盐浸泡60 d、120 d后,0~5 mm处的自由氯离子浓度最高分别降低了28.4%和15.3%;电通量与表观氯离子扩散系数之间存在良好的线性关系;GO有效调节了水化产物形状,减少了内部孔隙,使其微观结构更加密实,从而提升了水泥砂浆抗氯离子渗透性能。