比密粘度和特性粘数的计算及改正

本文导出毛细管粘度计的比密粘度方程: v=η/ρ=At-Bt~(-1)+C 式中-Bt~(-1)和C分别代表动能改正和残液改正。方程在宽的粘度范围内有良好精度。本文提出,准确的特性粘数[η]与忽略任何改正的特性粘数[η]~*之间存在简单的线性关系。例如从以上方程可写出[η]=(1+k_e-k_v)[η]~*+δρ式中k_e=2Bt_o~(-1)/At_0+Bt_0~(-1)+C), k_v=C/(At_0-Bt_0~(-1)+C), δρ=(ρ_1-ρ_0)/(c_1ρ_0), 它们分别是代表动能改正、残液改正和密度改正的常数。利用以上特性粘数改正公式, 可在确保准确性的前提下极大地简化特性粘数的改正计算。     

化合物Mo(CO)~n^+(n=1～6)构型和键离能的密度泛函研究

采用DFT/B3LYP方法研究了化合物Mo(CO)~n^+(n=1～6)的基态可能构型,对于各n值,基态可能构型(电子态)依次为：直线型(^6∑^+),直线型(^6∑~g^+),C~2~υ(^2A~2)或D~3~h(^6A~1),D~4~H(^4A~1~g),C~2~ν(^2B~2)或C~4~ν'(^2B~1),D~3~d(^2A~1~g)。计算结果表明,对于n≥3时,碎片离子的构型与体系自旋多重度关系敏感。进一步计算了Mo－CO键的逐级解离能,计算值与实验结果能较好吻合,并从Mo原子4d和5s轨道杂化角度来解释该键解离能随n值的非单调变化。     

化合物Mo(CO)~n^+(n=1～6)构型和键离能的密度泛函研究

采用DFT/B3LYP方法研究了化合物Mo(CO)~n^+(n=1～6)的基态可能构型,对于各n值,基态可能构型(电子态)依次为：直线型(^6∑^+),直线型(^6∑~g^+),C~2~υ(^2A~2)或D~3~h(^6A~1),D~4~H(^4A~1~g),C~2~ν(^2B~2)或C~4~ν'(^2B~1),D~3~d(^2A~1~g)。计算结果表明,对于n≥3时,碎片离子的构型与体系自旋多重度关系敏感。进一步计算了Mo－CO键的逐级解离能,计算值与实验结果能较好吻合,并从Mo原子4d和5s轨道杂化角度来解释该键解离能随n值的非单调变化。     

高聚物表征中凝胶色谱与自动粘度计的联用技术

就凝胶色谱(GPC)与自动粘度计联用技术而言,在实验上必须注意严格控制温度及避免粘度计器壁效应。在处理数据时应考虑浓度检测器和粮度计之间的连结管道死体积△V和虹吸管残留液的影响。另外如以(η_r-1)/C计算各级分的特性粘数时由于各级分的聚合物浓度不同将引进不同程度的误差。我们用一点法公式计算每级分粘度避免了这种误差。     

用强阴离子交换毛细管电色谱分离阴离子化合物

对阴离子性化合物在强阴离子交换毛细管电色谱中的保留行为进行了研究。发现样品中固定相上的吸附使样品的保留因子k^*变小,柱小的分离能力减小;而电压的增大,使酸性样品的k^*也增大,并且电压的改变也能改变分离的选择性;样品保留因子的对数值随着缓冲液离子强度的对数值的增大而线性减小;样品也强阴子交换毛细管电谱和毛细管区带电泳中有不同的保留行为。     

二元络合体系的毛细管电泳相互作用分析

建立了一种利用毛细管电泳相互作用测定络合比为1：2的二元络合体系各级络合常数。依据所设计的毛细管电泳二级峰漂移模型,利用间接紫外检测方法,在运行电压为30kV、缓冲溶液组成为咪唑和醋酸（pH5．50）的条件下,测定了Mg^2＋与草酸体系的相互作用参数,求出了Mg^2＋与草酸的一级条件稳定常数的对数值为lgK1=3．40,二级条件稳定常数对数值lgK2=0．90,与文献值具有较好的一致性。     

傅里叶变换表面等离子体共振频率对金膜表面溶液折射率响应

采用新型傅里叶变换表面等离子体共振仪（FT-SPR）,测定了NaCl、KCl和乙醇3种水溶液在不同浓度下的SPR响应值,建立了SPR响应与溶液浓度和折射率之间的定量关系R=1.53×105(n -1.3333),测定了FT-SPR 100型仪器的折射率响应常数m=1.53×105,即液体折射率每变化0.000 1,FT-SPR响应值变化为15 cm-1。 其结果为用FT-SPR直接测定液体样品的折射率提供了可能。     

利用气相色谱仪进行吸收反应速率常数的测定

为了测定气液化学吸收过程的反应速率常数和其它吸收过程参数,国内外曾采用精心设计加工的湿壁塔、湿壁球、层流射流器和转鼓等装置。它们多数存在所谓端末效应(End effect)、进口效应(Entrance effect)、刚性膜(Rigid film)和波纹的干扰以及气液界面处液流速的准确估测问题。 作者最近提出一种将脉冲-响应技术同静止吸收液相结合的测定吸收参数新法,并完成了数学模型分析。根据分析,若被吸收气体的一个脉冲气样流经长度L、宽度W的静止吸收液池,则部分气样将溶入吸收液,进而边扩散进入液内,边同吸收剂反应。若该反应为一级不可逆反应或拟一级不可逆反应,则反应速率常数为:     

硼酸盐水溶液热力学研究: 4.离子对[CaB(OH)~4]^+标准缔合 常数的确定

在温度为278.15-318.15K范围内测定了含有不同Li~2B~4O~7和CaCl~2浓度测试液的无液接电池:Pt,H~2(101.325kPa)|Li~2B~4O~7(m~1),CaCl~2(m~2)|AgCl-Ag的电动势E(V)。在Pitzer电解质溶液理论基础上,用线性外推法确定离子对[CaB(OH)~4]^+的标准缔合常数K~d,并得到K~d随温度T变化的经验公式:pK~d=0.6857-359.72/T-4.632×10^-^3T。同时计算得到了离子对缔合过程的热力学函数,指出形成该离子对的推动力是缔合熵。     

葡萄糖水溶液中碳酸盐热力学研究 1.二氧化碳-碳酸氢钠-氯化钠-葡萄糖-水体系

在278.15～318.15K和一定离子强度范围内,测定了无液接电池Pt,(1-x)H~2+xCO~2│NaHCO~3(m~1),NaCl(M~2),.CO~2(m~3),葡萄糖(m~4)│AgCl-Ag的电动势,利用改进的Harned外推法和我们提出的多项式拟合法确定了二氧化碳在15%葡萄糖水溶液中的一级酸常数K 两种方法所得PK 值在实验误差范围内一致.PK 随温度变化符合经验方程PK =A~1+A~2/T+A~3T,并计算了二氧化碳在葡萄糖水溶液中解离过程的各热力学量.     

Li~3Al的几何结构和垂直激发态光谱的量子化学研究

在ab initio DZP水平上, 用能量梯度法对Li~3Al的三种几何构型进行了优化, 并对其中两个能量较低的构型用单、双激发组态相互作用(CISD)进行了垂直跃迁能和振子强度计算, 结果表明: Li~3Al(C~2~v)中存在着三个强度较大的跃迁, 分别是从基态跃迁到1^1B~1, 2^1B~1, 5^1A~1态。Li~3Al(D~3~h)中存在着四个强度较大的跃迁, 分别是从基态跃迁到1^1B~2, 2^1A~1, 3^1B~2, 3^1A~1态。这些强度较大的跃迁均为粒子穴跃迁。     

Use of accurate absolute gas viscosity measurements to test the classical slip correction for capillary viscometers at 25°C and 1 atm. II. Comparison of results for stainless steel and pyrex glass surfaces for the pure gases and for mixtures of helium and argon

The precise gas viscosity measurements of Kestin and co-workers and a simple capillary viscometer have been used to test the classical slip correction at 25°C and one atmosphere for pyrex glass and stainless steel surfaces. Data are also presented for mixtures of helium and argon, and an empirical expression for applying slip corrections to viscosities of mixtures is tested.     

Analysis of protein denaturation by high-performance continuous differential viscometry

The intrinsic viscosity of protein solutions changes when denaturation occurs. Therefore, viscosity measurement using traditional glass capillary viscometers has been a key method to study the process of protein denaturation. Such measurements are laborious, time consuming and need at least 10 ml of sample. The Viscotek differential viscometer can be used as an on-line detector for high-performance liquid chromatography to monitor the viscosity of column effluent. In this study, samples were injected using an autosampler onto a "delay" column containing glass beads in place of the high-performance liquid chromatography columns. Results indicate guanidine hydrochloride, heat and pH act as denaturing agents and changes the intrinsic viscosities of serum albumin, turkey egg albumin, and ovalbumin solutions. The differential viscometer is sensitive and provides accurate measurements of minor changes in viscosities of very dilute protein solutions undergoing denaturation. The advantage of using the differential viscometer instead of conventional glass capillary viscometer is the increased sensitivity, precision, speed and operational ease that permits measurements of solution viscosity of low sample concentrations up to 1.2 micrograms of pure proteins.     

Analysis of interfacial phenomena of aqueous solutions of polyethylene oxide and polyethylene glycol flowing in hydrophilic and hydrophobic capillary viscometers

Viscosities of aqueous solutions of five polyethylene oxide (PEO) samples with molar masses from 1.5 x 10(5) to 1.0 x 10(6) were carefully measured in a polytetrafluoroethylene (PTFE) capillary Ubbelohde viscometer in the concentration range from dilute down to extremely dilute concentration regions and compared with those of the same sample obtained from a glass capillary viscometer. At the same time, viscosities of aqueous solutions of three PEG samples in glass and paraffin-coated capillary viscosity were measured. The wall effects occurred in viscosity measurements for PEO and PEG aqueous solutions in different capillary viscometers were theoretically analyzed and discussed. It was found that different interfacial behaviors occurred in both hydrophobic and hydrophilic capillary viscometers respectively and the interfacial behaviors also exhibit molar mass dependence.     

EFFECT OF ADSORPTION ON THE VISCOSITY OF DILUTE POLYMER SOLUTION*

Careful measurements of the dilute solution viscosities of polyethylene glycol and polyvinylalcohol in water were carried out. The reduced viscosities of both polymer solutions plot upward curves atextremely dilute concentration levels similar to the phenomena observed for many polymer solutions in theearly 1950's. Upon observation of the changes of the flow times of pure water in and the wall surfacewettability of the viscometer after measuring solution viscosity, a view was formed that the observed viscosityabnormality at extremely dilute concentration regions is solely due to the effect of adsorption of polymerchains onto the wall surface of viscometer. A theory of adsorption effect based on the Langmuir isothermswas proposed and a mathematical analysis for data treatment was performed. The theory could adequatelydescribe the existing viscosity data. It seems necessary to correct the viscosity result of dilute polymersolutions measured by glass capillary viscometer by taking into account the effect of adsorption in all cases.     

聚氧化乙烯水溶液粘度的测定

测定了不同分子量聚氧化乙烯(PEO)在水溶液中的粘度，发现在低浓度区高分子溶液比浓粘度出现负偏离。用高分子溶液流过时间对浓度作图的外推值t0^*重新计算相对粘度，则高分子溶液比浓粘度与浓度之间满足线性关系。不同分子量PEO水溶液流过时间对浓度作图的外推值t0^*是完全一致的。利用纯溶剂在粘度计中流过时间的改变确定了高分子在毛细管管壁上吸附层的厚度，发现PEO在毛细管管壁上吸附层厚度与分子量无关。     

Viscosity of dilute colloidal dispersions involving polysaccharide-based stabilizers

The viscosity of oil-in-water emulsions stabilized by amphiphilic derivatives of dextran (a neutral bacterial polysaccharide) was studied. The oil volume fraction was kept lower than 20% and the mean droplet diameter remained between 200 and 300 nm. The effects of temperature and oil volume fraction on emulsion viscosity were examined using a capillary viscometer. Andrade equation was shown to conveniently account for the variation of viscosity with temperature. Semiempirical equations were derived for the variation of activation energy with oil volume fraction. The established equations were extended to other emulsions using literature data.     

Use of precise absolute gas viscosity measurements to test the classical slip correction for capillary viscometers at 25°C and 1 atm

Precise gas viscosity measurements of Kestin and coworkers and a simple capillary viscometer have been used to test the classical slip correction at 25°C and one atmosphere pressure. The results indicate that for capillaries with diameters between 0.015 and 0.025 cm. this correction is two to three times smaller than normally used.