Prediction of surface and interfacial tension based on thermodynamic data and CALPHAD approach

In this article, following a brief introduction concerning experimental measurements of surface and interfacial tensions, methods for calculating surface tension and surface segregation for binary, ternary, and multicomponent high-temperature melts based on Bulter＇s original treatment [ 1] and on available physical properties and thermodynamic data, especially excess Gibbs free energies of bulk phase and surface phase versus temperature obtained from thermodynamic databases using the calculation of phase diagram （CALPHAD） approach, with special attention to the model parameter β, have been described. In addition, the geometric models can be extended to predict surface tensions of multicom- ponent systems from those of sub-binary systems. For illustration, some calculated examples, including Pb-free soldering systems and phase-diagram evaluation of binary alloys in nanoparticle systems are given. On the basis of surface tensions of high-temperature melts, interracial tensions between liquid alloy and molten slag as well as molten slag and molten matter can be calculated using the Girifalco-Good equation [2]. Modifications are suggested in the Nishizawa＇s model [3] for estimation of interracial tension in liquid metal （A）/ceramics （MX） systems so that the calculations can be carried out based on the sublattice model and thermodynamic data, without deliberately differentiating the phase of MX at high temperature. Finally, the derivation of an approximate expression for predicting interfacial tension between the high-temperature multicomponent melts, employing Becker＇s model [4] in conjunction with Bulter＇s equation and inteffacial tension data of the simple systems is described, and some examples concerning pyrometallurgical systems are given for better understanding.

AN APPROACH TO CALCULATE THE SURFACE TENSION OF THE LIQUID NITROGEN FILM ON SOLIDS FROM AN ADSORPTION ISOTHERM

The equations, used in this paper to calculate the surface tension of the liquid nitrogen film formed by the physical adsorption on many different model solids (e.g. spherical partiele, plane particle and spherical cavity pores or cylindrical pores at the openings of both ends in solid bodies), have been derived on the thermodynamie principle. The calculated results have shown that the surface tension (γ) of the adsorbed liquid nitrogen film on most of non-porous solid surfaces diminishes with the rise of the nitrogen gas pressure (p) or of the adsorbed layers (n) at 77.3K; when p reaches the vapour pressure (p_s) of the bulk liquid nitrogen, y turns into the surface tension (γ_o) of the bulk liquid nitrogen; whgn p /p, 【0.98, there is an obvious difference between γ and γ_O.

Interactions of ferro-nanoparticles(hematite and magnetite) with reservoir sandstone: implications for surface adsorption and interfacial tension reduction

There are a few studies on the use of ferro-nanofluids for enhanced oil recovery,despite their magnetic properties;hence,it is needed to study the adsorption of iron oxide(Fe2 O3 and Fe3 O4) nanoparticles(NPs) on rock surfaces.This is important as the colloidal transport of NPs through the reservoir is subject to particle adsorption on the rock surface.Molecular dynamics simulation was used to determine the interfacial energy(strength) and adsorption of Fe2 O3 and Fe3 O4 nanofluids infused in reservoir sandstones.Fourier transform infrared spectroscopy and X-ray photon spectroscopy(XPS) were used to monitor interaction of silicate species with Fe2 O3 and Fe3 O4.The spectral changes show the variation of dominating silicate anions in the solution.Also,the XPS peaks for Si,C and Fe at 190,285 and 700 eV,respectively,are less distinct in the spectra of sandstone aged in the Fe3 O4 nanofluid,suggesting the intense adsorption of the Fe3 O4 with the crude oil.The measured IFT for brine/oil,Fe2 O3/oil and Fe3 O4/oil are 40,36.17 and 31 mN/m,respectively.Fe3 O4 infused with reservoir sandstone exhibits a higher silicate sorption capacity than Fe2 O3,due to their larger number of active surface sites and saturation magnetization,which accounts for the effectiveness of Fe3 O4 in reducing IFT.

FOURIER-TRANSFORM INFRARED SPECTROSCOPIC STUDIES ON THE INTERACTION AMONG MARINE TRACE METAL IONS , SOLID PARTICLES AND ORGANICS Ⅱ. THE STEP WISE CHANGE IN THE SURFACE HYDROXYL GROUPS

IR spectra of Cu (Ⅱ)-marine solid particle systems show that Cu (Ⅱ)-marine solid particle ion exchange causes a stepwise change in the surface H-bonding hydroxyl groups on illite . montmorillonite, CaCO3,r. AlOOH and goethite, but that this does not affect the surface free hydroxyl groups on illite. montmorillonite and CaCO3. and framework hydroxyl group on goethite and on γ- AlOOH . Over the range of Cu(Ⅱ) exchange amounts in the present experiment, four stepwise changes were discovered for the surface H- bonding hydroxyl group on illite. while two stepwise changes were observed on the other marine solids. The interfacial stepwise ion exchange theory was first demonstrated by the above experimental evidence .

Relation between Tolman length and isothermal compressibility for simple liquids

The Tolman length δ 0 of a liquid with a plane surface has attracted increasing theoretical attention in recent years,but the expression of Tolman length in terms of observable quantities is still not very clear.In 2001,Bartell gave a simple expression of Tolman length δ 0 in terms of isothermal compressibility.However,this expression predicts that Tolman length is always negative,which is contrary to the results of molecular dynamics simulations（MDS） for simple liquids.In this paper,this contradiction is analyzed and the reason for the discrepancy in the sign is found.In addition,we introduce a new expression of Tolman length in terms of isothermal compressibility for simple fluids not near the critical points under some weak restrictions.The Tolman length of simple liquids calculated by using this formula is consistent with that obtained using MDS regarding the sign.

Substrate elastic deformation due to vertical component of liquid-vapor interfacial tension

Young＇s equation is a fundamental equation in capillarity and wetting, which reflects the balance of the horizontal components of the three interracial tensions with the contact angle （CA）. However, it does not consider the vertical component of the liquid-vapor interracial tension （VCLVIT）. It is now well understood that the VCLVIT causes the elastic deformation of the solid substrate, which plays a significant role in the fabrication of the microfluidic devices because of the wide use of the soft materials. In this paper, the theoretical, experimental, and numerical aspects of the problem are reviewed. The effects of the VCLVIT-induced surface deformation on the wetting and spreading, the deflection of the microcantilever, and the elasto.capillarity and electro- elasto.capillarity are discussed. Besides a brief review on the historical development and the recent advances, some suggestions on the future research are also provided. Key words

Dynamics along the epithelial-cancer biointerface:Hidden system complexities

The biointerface dynamics influence any cancer spreading through the epithelium since it is documented in the early stages some malignancies(like epithelial cancer).The altered rearrangement of epithelial cells has an impact on the development of cancer.Therefore,it is necessary to comprehend the underlying biological and physical mechanisms of this biointerface dynamics for early suppression of cancer.While the biological mechanisms include cell signaling and gene expression,the physical mechanisms are several physical parameters such as the epithelial-cancer interfacial tension,epithelial surface tension,and compressive stress accumulated within the epithelium.Although the segregation of epithelia-cancer co-cultured systems was widely investigated,the role of these physical parameters in cell reorganization is still not fully recognized.Hence,this review is focused on clarifying the role that some physical parameters have during cell reorganization within the epithelial cell clusters and cancer spread within co-cultured spheroids.We have applied the developed biophysical model to point out the inter-relations among physical parameters that influence cell reorganization within epithelial-cancer co-cultured systems.The main results of this theoretical consideration have been assessed by integrating the biophysical model with biological and bio-mechanical experiments from the available literature.The epithelial-cancer interfacial tension leads to the reduction of the biointerface area,which leads to an increase in the compressive residual stress within the epithelial clusters depending on the viscoelasticity of the epithelial subpopulation.This stress impacts epithelial rearrangement and the dynamics along the biointerface by influencing the epithelial surface tension and epithelial-cancer interfacial tension.Further,the interrelation between the epithelial surface tension and epithelial-cancer interfacial tension influences the spread of cancer cells.

驱油流体吸附抑制剂的合成与评价

目的在化学驱的实施过程中,地层对驱油剂的吸附滞留是表面活性剂进入地层后含量损失的一种主要原因,为了减少驱油流体在地层的损耗成本而展开对驱油液体吸附抑制剂的研究。方法以二氰二胺(DCD)、1-十八胺盐酸盐(OHC)为原料,基于亲核加成的原理采用熔融法在150℃下合成了一种针对驱油流体的吸附抑制剂OHCB,该表面活性剂同时具备强疏水基、强极性原子和阳离子基团,因此具有较强的占据黏土矿物表面吸附位点的能力。对其进行了红外吸收、紫外吸收、元素分析、质谱等结构表征,采用静态吸附法研究了其作为添加剂的最佳配比,并验证在最佳配比下对驱油剂AEO7的吸附抑制效果,以及该体系相较AEO7单一体系的静态洗油效率、乳化性及润湿性的变化。结果OHCB抑制驱油剂AEO7在黏土矿物表面的吸附效果较好,在驱油剂与吸附抑制剂质量比为5∶1的情况下,抑制效果可达27%以上。结论OHCB不仅具有较好的吸附抑制效果,且其加入使AEO7的静态洗油效率提升至27.3%、γc m c降至27.1 mV/m,CMC降至38 mg/L、油-水界面张力降至0.5 mV/m以下,对体系性能起到了协同增效的作用,并且相较于需要预吸附的牺牲剂,其使用更为便捷。

基于问题导向的物理化学实验项目设计与改进——以液体表面张力测定为例

以日常生活现象(洗衣时的白色絮凝物)为切入点,通过问题导向,引导学生自主设计实验。将表面张力的测量融入探究生活现象背后化学原理的过程中,综合运用多种技术手段,建立“发现问题-探索实践-回归课本”的探索型实验模式,从而巩固学生对胶体与界面化学知识点的理解。改进后的实验内容更丰富,挑战度更高,综合性更强,趣味性更浓,有利于培养学生分析和解决问题的能力,能更好地培养学生的探究性思维。此外,本实验安全性较高,易于操作,对设备无特殊要求,非常适合本科教学实验。

High-Quality and Wafer-Scale Cubic Silicon Carbide Single Crystals

Cubic silicon carbide(3C-SiC)has superior mobility and thermal conduction over that of widely applied hexagonal 4H-SiC.Moreover,much lower concentration of interfacial traps between insulating oxide gate and 3C-SiC helps fabricate reliable and long-life devices like metal-oxidesemiconductor field effect transistors.However,the growth of high-quality and wafer-scale 3C-SiC crystals has remained a big challenge up to now despite decades-long efforts by researchers because of its easy transformation into other polytypes during growth,limiting the development of 3C-SiC-based devices.Herein,we report that 3C-SiC can be made thermodynamically favored from nucleation to growth on a 4H-SiC substrate by top-seeded solution growth technique,beyond what is expected by classical nucleation theory.This enables the steady growth of high-quality and large-size 3C-SiC crystals(2-4-inch in diameter and 4.0-10.0 mm in thickness)sustainable.The as-grown 3C-SiC crystals are free of other polytypes and have high-crystalline quality.Our findings broaden the mechanism of hetero-seed crystal growth and provide a feasible route to mass production of 3C-SiC crystals,offering new opportunities to develop power electronic devices potentially with better performances than those based on 4H-SiC.

MgO含量对CaO-Al_(2)O_(3)-TiO_(2)基连铸保护渣界面性质的影响

高钛钢连铸生产过程中结晶器内的钢渣界面反应较为严重,易造成连浇困难、铸坯品质下降等问题。利用热丝法对3%、8%、10%三种不同MgO质量分数的保护渣接触角进行了测定,并基于此计算出表面张力和渣钢界面张力,此外结合拉曼光谱和Scigress软件模拟,从微观结构的角度分析了MgO含量与渣钢界面张力的变化规律。研究结果表明,1723 K温度下,保护渣中MgO质量分数为3%、8%、10%时,接触角为35°、36.7°、39.8°;保护渣的表面张力为516.3、523.1、525.6 mN/m;渣钢界面张力为1421、1425、1440 mN/m。MgO质量分数在8%~10%时,渣钢界面张力上升速率明显加快,导致钢渣间的界面反应减弱,使得钢渣更容易分离。

运用表面张力测试仪研究氯乙烯聚合体系

运用克吕士K100表面张力测试仪,研究氯乙烯聚合所用分散剂和引发剂的表面张力;以1,2-二氯乙烷为重相,混合液为轻相,研究其界面张力。设计了不同的5 L聚合配方体系,跟踪氯乙烯悬浮聚合中的表面张力变化情况。

Experimental study of evaporation of sessile water droplet on PDMS surfaces

Evaporation of sessile water droplet on polydimethylsiloxane （PDMS） surfaces with three different curing ratios （5：1, 10：1, and 20：1） was experimentally investigated in this paper. We show that the constant contact radius （CCR） evaporation on surface with high curing ratio lasts longer than that with low curing ratio. We also measured Young＇s moduli of PDMS films by using atomic force microscopy （AFM） and simulated surface deformation of PDMS films induced by sessile water droplet. With increasing curing ratio of PDMS film, Young＇s modulus of PDMS film is getting lower, and then there will be larger surface deformation and more elastic stored energy. Since such energy acts as a barrier to keep the three-phase contact line pinned, thus it will result in longer CCR evaporation on PDMS surface with higher curing ratio.

Study on the Crystallization Mechanism of Spectinomycin Dihydrochloride

The growth mechanism of spectinomycin dihydrochloride crystal in pure water and acetone-water mixture at different temperatures has been studied by induction period measurement. The induction period was measured visually. The solid-liquid interfacial tension was determined on the basis of classical homogenous nucleation theory and the surface entropy factor was calculated. It was shown that the interfacial tension and surface entropy factor increased with the increase of acetone concentration and the decrease of temperature. It was demonstrated that the growth mechanism of spectinomycin dihydrochloride crystal was controlled by birth and spread growth in pure water or in acetone-water mixture at high temperatures and turned from birth and spread growth to spiral growth with the increase of acetone concentration in acetone-water mixture at low temperatures.

A three-dimensional robust volume-of-fluid solver based on the adaptive mesh refinement

The present study provides a three-dimensional volume-of-fluid method based on the adaptive mesh refinement technique.The projection method on the adaptive mesh is introduced for solving the incompressible Navier-Stokes equations.The octree structure mesh is employed to solve the flow velocities and the pressure.The developed solver is applied to simulate the deformation of the cubic droplet driven by the surface tension without the effect of the gravity.The numerical results well predict the shape evolution of the droplet.

Surface tensometry studies on formulations of surfactants with preservatives as a tool for antimicrobial drug protection characterization

The aim of the work was to quantify possible interactions between surfactants and preservatives, comparing surface properties, in model pharmaceutical formulations. Surface parameters of 2-component surfactant-preservative aquous mixtures were determined with a Wilhelmy plate technique, for the so-called principal surfactants (polysorbate 80, egg lecithin, phosphatidylcholine) and preservatives, which were methylparaben and benzalkonium chloride (BA-C). A generalized surface tension vs. surfactant concentration plot signatures, in the presence of preservative at a fixed amount, allowed: the critical micellar concentration (cmc) shift, additive molecules partition from the surface to the bulk, mixed micelles formation concentration, and additive surface removal concentration to be determined in reference to surface activity of the added substance. Methylparaben is a compound of lower (in comparison to BAC) surface activity, lower partitioning coefficient possessing lower energy and concentration of its removal from the surface, that makes it play effectively an antimicrobial protection role in the bulk of pharmaceutical products, as already shown by chemical tests.

Effect of diluent on interfacial emulsion in copper solvent extraction

The organic phase extracted from interfacial crud of copper solvent extraction at Dexing Copper Mine was analyzed for its different components by combined gas chromatography mass spectroscopy. It was found that the main impurities in organic phase were methylnaphthalenes and di methylnaphthalenes which originated from commercial 260# kerosene used as diluent. It was found that the impurities containing diluent was unfavorable to phase disengagement. Methods were suggested to improve diluent properties to prevent stable interfacial emulsion.

Wilhelmy吊片法测定磷脂溶液的表面张力等温线

表面活性物质的表面张力等温线测定是大学物理化学实验的重要内容。随着磷脂类表面活性剂的广泛应用,有必要在大学化学中更新经典表面张力等温线测定的实验内容,并使学生掌握先进的测量方法。以二硬脂酰基磷脂酰胆碱(DSPC)和二棕榈酰基磷脂酰胆碱(DPPC)为研究对象,应用界面张力仪测定了两种溶液表面张力等温线,计算了其表面超量和分子横截面积,并设计了拓展性实验内容,对于培养学生分析问题和解决问题的能力具有积极的意义。

油茶皂苷与月桂酰肌氨酸钠二元混合物的协同作用研究

目的:探究油茶皂苷与月桂酰肌氨酸钠(Sodium lauroyl sarcosinate,SLS)之间的协同作用。方法:考察油茶皂苷的加入对复配体系表面活性的影响,并探究复配体系在不同条件下的稳定性。结果:复配体系中加入质量分率(α_(1))为1%的油茶皂苷时,其临界胶束浓度(Critical micelle concentration,CMC)增效12.35%,表面张力(γ)比SLS低4.12%;体系的接触角为23.9°,相比于油茶皂苷的接触角减小23°,润湿性大幅提升。当α_(1)为1%、10%时,发泡体积相比油茶皂苷分别增效85.04%、72.68%。在α_(1)=4%时,泡沫稳定性相较于SLS增效11.35%。油茶皂苷-SLS复配体系在高温下稳定性优异,具有良好的抗硬水能力;在盐离子和酸性条件下,复配体系的CMC显著降低,表面活性提高。结论:油茶皂苷-SLS复配体系在表面活性上存在良好的协同效应,油茶皂苷的生产及应用不仅有利于日用化学工业的发展,而且对充分开发利用茶籽饼这一天然资源具有较大的实际意义。

阴非离子表面活性剂的合成及其作为渗吸剂的性能研究

以辛基酚聚氧乙烯醚和马来酸酐为原料、对苯甲磺酸为催化剂,合成一种可提高致密油压裂液体系渗吸效率的阴非离子表面活性剂BGT-16。通过红外光谱和核磁共振氢谱对BGT-16分子结构进行表征,并对BGT-16的表界面张力、临界胶束浓度、润湿性能、自发渗吸效率等性能进行了测试。结果表明,质量分数为0.3%的BGT-16的表面张力为33.88 mN/m、界面张力为3.52 mN/m、CMC为1.19×10^(-4)mol/L,其γCMC为33.66 mN/m,具备良好的表面活性,对疏水载玻片具有良好的润湿性能;合成的BGT-16的渗吸效率受高盐环境影响较小、适用范围广。