分散剂浓度、遮光度、超声分散时间对钼粉粒度分布测试结果影响的分析研究

本文通过研究Mastersizer2000型激光粒度分析仪,在不同浓度的分散剂,不同的遮光度,以及不同的超声波分散时间3个方面,对测定钼粉的粒度分布测试结果所造成的影响,从而找出钼粉粒度分布测试的最佳条件,为钼粉性能的判定提供准确的数据。

SiO2颗粒分散液浓度对建筑结构钢锌系复合磷化膜耐蚀性的影响

通过硫酸铜点滴实验、静态浸泡实验以及电化学阻抗谱测试,以变色时间、电荷转移电阻、低频阻抗模值等作为指标,研究了SiO2颗粒分散液浓度对锌系复合磷化膜耐蚀性的影响。结果表明:SiO2颗粒分散液浓度对磷化膜的耐蚀性有较显著的影响,随着SiO2颗粒分散液浓度从10 mL/L增加到60 mL/L,磷化膜变色时间从116 s逐渐延长到170 s,电荷转移电阻从1.170 kΩ·cm2逐渐增大到4.580 kΩ·cm2,低频阻抗模值从0.635 kΩ·cm2逐渐增大到3.845 kΩ·cm2,说明磷化膜的耐蚀性有较大幅度提高。随着SiO2颗粒分散液浓度从60 mL/L继续增加到80 mL/L,磷化膜变色时间、电荷转移电阻和低频阻抗模值都变化不大,其耐蚀性未进一步提高。但SiO2颗粒分散液浓度超过80 mL/L后,磷化膜的耐蚀性明显变差。

高浓度粉末分散型降凝剂的研制及评价

苏丹Heglig油田生产的稠油对CNPC型降凝剂的感受性变差,改性效果不佳。为了保证管道的安全运行,研制开发了适合当前苏丹混合原油输送的新型高浓度粉末分散型降凝剂,并进行了室内改性效果评价。评价结果表明,该型降凝剂在降凝、降粘及抑制蜡析出等性能均超过了苏丹现在所使用的CNPC型降凝剂。

氧化石墨烯和石墨烯的高浓度加工、致密化及应用

由紧密堆叠的石墨烯片组成的致密石墨烯组件具有出色的化学稳定性和优异的力学、热学和电学性能。致密石墨烯组件不存在多孔石墨烯气凝胶中密度低、力学强度低、导电性差和导热性差等问题,是未来便携式电子和智能设备的理想材料。本文对制备方法进行了总结,包括利用机械分散、蒸发浓缩、离心浓缩和液相剥离法获得的高浓度氧化石墨烯(GO)和石墨烯分散液,以及利用真空辅助过滤、界面自组装和压制成型法获得的二维(2D)致密石墨烯基薄膜和三维(3D)致密石墨烯基结构,并评估了各种方法的优缺点。此外,还总结了致密石墨烯基组件在储能、热管理和电磁干扰(EMI)屏蔽方面的应用。最后,概述了致密石墨烯组件在未来研究中面临的挑战和前景。本综述为探索和开发大规模、低成本的制造技术和面向应用的致密石墨烯组件提供参考。

SHMP分散配制用于环境风险模拟研究的纳米ZnO颗粒溶胶

选择SHMP(六偏磷酸钠)作分散剂,研究超声时间与静置时间对商购纳米ZnO的优化分散效果,以配制出用于环境风险模拟研究中的分散粒径小、效果稳定且浓度较高的纳米ZnO颗粒溶胶.结果表明,相同条件下加分散剂的体系分散效果好于不加分散剂体系.最佳优化分散方法:在100 mL超纯水中先加入45 mg SHMP作分散剂,再加入0.5 g的商购纳米ZnO,超声60min后静置6 d,最终得到的颗粒溶胶平均粒径为(176.5±15)nm(纳米粒度-Zeta电位仪),TEM表征粒径为60～90 nm,Zeta电位为(-64.7±5.64)mV,实测分散浓度为(95.87±4.37)mg/L,其稳定性基本可以维持5 d.

pH响应型P(HEMA/MAA)纳米微凝胶分散液的凝胶化行为和流变性能

制备了在修复受损组织方面有应用潜能的纳米级聚(甲基丙烯酸羟乙酯/甲基丙烯酸)(P(HEMA/MAA))微凝胶;采用试管倒转法对不同pH值和浓度的P(HEMA/MAA)微凝胶分散液的凝胶化相转变行为进行了研究;借助椎板流变仪考察了低浓度和高浓度微凝胶分散液的流变性能,并对pH触发物理凝胶化相转变机理进行了推测.结果表明:在生理pH值环境下,一定浓度的P(HEMA/MAA)微凝胶分散液可以发生凝胶化相转变形成凝胶态,pH=7时,HEMA/MAA进料摩尔比为8/2的微凝胶分散液凝胶化后得到的凝胶力学性能最佳,最大弹性模量(G')可达7.58×103Pa;P(HEMA/MAA)微凝胶颗粒在不同条件下具有不同的溶胀效果,导致低浓度分散液的表观粘度发生相应的变化,并由此推测出微凝胶颗粒的溶胀过程由外及内,分为三个阶段;高浓度微凝胶分散液发生凝胶化相转变主要是由颗粒间或颗粒与分散介质间形成的空间静电稳定作用和氢键共同作用引起的.

含聚合物油泥对原油稳定性及油品性质的影响

以渤海油田某一区块为例,采用把油泥加入到脱水合格的外输原油中,通过海底管道输送回陆地的方法来解决海上油田含聚合物油泥处理问题,并验证此方法的可行性。利用测定乳状液颗粒粒径、Zeta电位、电导率的方法以及自然沉降法确定含聚合物油泥在原油中的分散稳定性。对加入油泥之后原油以及主要加工产品的性质进行分析,考察油泥的加入对原油基础性质的影响。结果表明:外输原油中最大可加入质量分数为0.5%的含聚合物油泥,不会产生油泥沉降堵塞海底管道的问题;加入0.5%油泥之后的原油黏度降低,流动性增强;减压渣油收率增加15%,15℃时延展度大于150 cm,渣油抗低温性能增强,有利于生产抗低温型重交通道路沥青。

纳米二氧化钛环境风险模拟研究的溶胶配制方法

为了优化用于环境风险模拟研究的纳米二氧化钛颗粒溶胶的制备方法,研究了超声时间、分散剂、静置时间对商购纳米二氧化钛分散效果的影响,从而确定出分散体系稳定、粒径小且二氧化钛浓度较高的纳米溶液,以促进工程纳米材料环境风险的研究。结果表明,在100 mL超纯水中先加入六偏磷酸钠(SHMP)500 mg作分散剂,再加入100 mg商购纳米二氧化钛,然后超声15 min,并静置6 d,最终可得到平均粒径为(196±20)nm,TEM表征粒径为50～80 nm,Zeta电位为(-51.3±6.7)mV,实测分散质量浓度为(61.89±5.41)mg/L的颗粒溶胶。该方法可获得较高浓度、稳定的纳米二氧化钛颗粒溶胶,可为工程纳米材料环境风险模拟研究奠定良好的基础。

多分散高浓度介质偏振光后向扩散散射的Monte Carlo仿真

建立了针对多分散高浓度介质偏振光后向扩散散射的MonteCarlo仿真模型,导出了多分散系统的有效自由程分布函数.给出了半径为50nm与550nm及其三种不同体积浓度比混合的聚苯乙烯微球作为散射粒子的高浓度介质的仿真结果.定性地分析了多分散介质偏振光后向扩散散射的光强空间分布特征与粒子的体积浓度比的关系.

激光衍射法测量ZrO_2粉末粒度实验条件的优化研究

利用激光衍射法对ZrO2 粉末进行粒度测量 ,分别从分散介质和样品浓度对测量条件进行优化设计。采用含 0 .2 % ,0 .4 % ,0 .6 % ,0 .8%及 1.0 %的六偏磷酸钠水溶液 ,在样品浓度为7% ,10 % ,13%和 16 %的情况下进行粒径分析。结果表明 ,在 0 .2 %～ 0 .4 %的六偏磷酸钠溶液下 ,样品浓度为 7%左右时所测得的结果较为理想。

激光散射式煤矿粉尘测量仪的设计原理

本文论述了激光散射式煤矿粉尘测量仪的基本原理,并根据煤矿测尘的实际需,进行理论分析,提出了具体的设计方案。

MATHEMATICAL ANALYSIS OF DRUG RELEASE FROM A MONOLITHIC MATRIX WITH AN INITIALLY LINEAR CONCENTRATION DISTRIBUTION

Based on the principle of chemical engineering in the multisubject field—drug delivery, the release kinetics of the slab monolithic matrix with an initially linear concentration distribution is studied in this paper. It can be used to describe the later stage when drug loading is above its solubility limit. A comprehensive model is proposed and the generalized solutions are acquired by Laplace transformation, from which a special case, i.e. a perfect sink has been deduced. According to the derived equations, the concentration profiles in the matrix has been computed and illustrated and the effect of volume of extraction medium on release has been investigated.

Theoretical design and distribution control of precipitates and solute elements in Al−Zn−Mg−Cu alloys with heterostructure

In order to simultaneously improve strength and formability,an analytical model for the concentration distribution of precipitates and solute elements is established and used to theoretically design and control the heterogeneous microstructure of Al−Zn−Mg−Cu alloys.The results show that the dissolution of precipitates is mainly affected by particle size and heat treatment temperature,the heterogeneous distribution level of solute elements diffused in the alloy matrix mainly depends on the grain size,while the heat treatment temperature only has an obvious effect on the concentration distribution in the larger grains,and the experimental results of Al−Zn−Mg−Cu alloy are in good agreement with the theoretical model predictions of precipitates and solute element concentration distribution.Controlling the concentration distribution of precipitates and solute elements in Al−Zn−Mg−Cu alloys is the premise of accurately constructing heterogeneous microstructure in micro-domains,which can be used to significantly improve the formability of Al−Zn−Mg−Cu alloys with a heterostructure.

Separation of Eu^3＋ Using a Novel Dispersion Combined Liquid Membrane with P507 in Kerosene as the Carrier

The separation of Eu^3 ＋is studied with a dispersion combined liquid membrane（DCLM）,in which polyvinylidene fluoride membrane（PVDF）is used as the liquid membrane support,dispersion solution containing HCl solution as the stripping solution,and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester（P507）dissolved in kerosene as the membrane solution.The effects of pH value,initial concentration of Eu3 ＋and different ionic strength in the feed phase,volume ratio of membrane solution to stripping solution,concentration of HCl solution, concentration of carrier,different stripping agents in the dispersion phase on the separation are investigated.The optimum condition for separation of Eu3 ＋is that concentration of HCl solution is 4.0 mol·L 1,concentration of carrier is 0.16 mol·L 1,and volume ratio of membrane solution to stripping solution is 30︰30 in the dispersion phase, and pH value is 4.2 in the feed phase.The ionic strength has no significant effect on separation of Eu3 ＋.Under the optimum condition,when the initial concentration of Eu3 ＋is 0.8×10 4mol·L 1,the separation percentage of Eu 3＋is 95.3%during the separation time of 130 min.The kinetic equation is developed in terms of the law of mass diffusion and the theory of interface chemistry.The diffusion coefficient of Eu3 ＋in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and their values are 1.48×10 7m 2·s 1and 36.6μm,respectively.The results obtained are in good agreement with literature data.

Modeling flame propagation speed and quenching distance of aluminum dust flame with spatially random distribution of particles

In this research combustion of aluminum dust particles in a quiescent medium with spatially discrete sources distributed in a random way was studied by a numerical approach.A new thermal model was generated to estimate flame propagation speed in a lean/rich reaction medium.Flame speed for different particle diameters and the effects of various oxidizers such as carbon dioxide and oxygen on flame speed were studied.Nitrogen was considered the inert gas.In addition,the quenching distance and the minimum ignition energy(MIE) were studied as a function of dust concentration.Different burning time models for aluminum were employed and their results were compared with each other.The model was based on conduction heat transfer mechanism using the heat point source method.The combustion of single-particle was first studied and the solution was presented.Then the dust combustion was investigated using the superposition principle to include the effects of surrounding particles.It is found that larger particles have higher values of quenching distance in comparison with smaller particles in an assumed dust concentration.With the increase of dust concentration the value of MIE would be decreased for an assumed particle diameter.Considering random discrete heat sources method,the obtained results of random distribution of fuel particles in space provide closer and realistic predictions of the combustion physics of aluminum dust flame as compared with the experimental findings.

Study on Control Strategy of Sulfur Dioxide Concentration in the Urban Area of Shijiazhuang

Two Gaussian air quality dispersion models, the industrial source complex short-term model (ISCST3) with and without modification have been used to simulate the pollutant concentration distribution in urban areas based on the meteorological data and the emissions distribution of sulfur dioxide. The verified data show that the modified model is more accurate in the urban area of Shijiazhuang. Using the modified model predictions, the control strategies of sulfur dioxide in the urban area have been studied, and the result show that the second long-term (to 2010) strategy can mitigate air pollution significantly and maintain pollution levels within permissible limits.

Influence of Cell Components Structure on Heat and Mass Transfer Phenomena in Single-Cell PEFC

The purpose of this study is to point out the dominant factor of heat and mass distribution in single-cell PEFC （polymer electrolyte fuel cell）. The numerical simulation by simple 3D model to clarify the influence of cell components structure on heat and mass transfer phenomena as well as power generation experiment and measurement of in-plane temperature distribution by thermograph was carried out. From the simulation, the gas channel pitch of separator was the key factor to unify in-plane distribution of temperature and gas concentration on reaction surface in cell. The compression of GDL （gas diffusion layer） by cell binding caused wider distribution of mass concentration in GDL. From the experiment, the power generation performance was promoted with decreasing gas channel pitch. The temperature range in observation area was reduced with decreasing gas channel pitch. It can be concluded that the power generation performance is promoted by decreasing gas channel pitch.

通向制革零排放的方法——开发生态友好的浸灰-复灰过程的浓度作用

制革准备工段的污染极其严重，其中超过60％的污染物都来自于浸灰-复灰过程。此工序中石灰和硫化碱的用量完全依赖于经验而非定量，石灰因其低溶解性而使皮获得逐步膨胀，但石灰的使用会产生很多环境问题。大量的石灰淤泥及固体废渣是其主要缺陷，而污水处理厂中的硫化物会产生危害作用。这些都是由于没有合理地使用石灰、硫化物、水及其它化料所致。本方法在准备工段中的化料用量都是最合适用量，这是基于使皮纤维分散的传统方法，仅需要20％～40％的水（以浸水前生皮重计），而在理论上仅使用传统浸灰-复灰过程中十分之一的化工材料量就可获得同样的浓度梯度。因此，本过程浸灰操作使用40％的水、0，35％的硫化钠和1％的石灰，用40％的水、1％的石灰进行复灰，而时间与传统方法一样。生皮经复灰后，其后各工序以常规工艺处理。另外用传统浸灰-复灰过程作为平行对比试验。结果表明，此工艺脱毛完全，纤维束分散程度与对比样相当。使用扫描电镜观察、铬成层分布分析及柔软度测试等来评价此方法，成革的物理性能、手感等与传统法生产的成革相一致。特别是有数据表明成革的柔软度与对比样相当。而与传统工艺相比，此工艺过程的COD及TS负荷各自减少了85％和12％，所产生的干污泥量由152kg／t原皮下降至6kg／t原皮。

氟化镧掺钕纳米激光材料的制备及光学性能

利用水热法制备了新型氟化镧掺钕(LaF3:Nd)纳米材料,其结构为六方晶型,纳米尺寸在25nm左右;利用超声波分散技术,制备成了一系列具有不同稀土分散浓度的纳米分散液。其钕离子浓度可达到1×1020 cm-3。可见-近红外透射光谱表明,对于5mm光程的纳米分散液,其在1053nm处的透射率大于85%,与掺钕透明陶瓷的透射率相当。荧光寿命测试结果显示,该稀土纳米材料(La0.95Nd0.05F3)在分散液中的寿命值为200μs,与粉末相比,降低了3.8%,表明这种低荧光猝灭率、高离子浓度、高透射率的纳米分散液将是一种可用于高重复率、高功率、超短脉冲的流体激光工作物质。

Two-dimensional finite element model to study calcium distribution in astrocytes in presence of excess buffer

In this paper a finite element model is developed to study cytosolic calcium concen- tration distribution in astrocytes for a two-dimensional steady-state case in presence of excess buffer. The mathematical model of calcium diffusion in astrocytes leads to a boundary value problem involving elliptical partial differential equation. The model con- sists of reaction-diffusion phenomena, association and dissociation rates and buffer. A point source of calcium is incorporated in the model. Appropriate boundary conditions have been framed. Finite element method is employed to solve the problem. A MATLAB program has been developed for the entire problem and simulated to compute the numer- ical results. The numerical results have been used to plot calcium concentration profiles in astrocytes. The effect of ECTA, BAPTA and aCa influx on calcium concentration distribution in astrocytes is studied with the help of numerical results.