表面特性对结霜和融霜排液的影响

对亲水表面、裸铝表面和疏水表面上结霜和融霜排液过程进行实验研究,分析了表面特性对冷凝水珠冻结、霜层生长和融霜排液的影响。结果表明：疏水表面上冷凝水珠呈规则球缺状、冻结较晚,而亲水表面和裸铝表面上冷凝水珠形状不规则;相比于亲水表面和裸铝表面上平整霜层,疏水表面上霜层不平整,有凹穴和凸起;疏水表面上霜层平均厚度增长较亲水表面和裸铝表面缓慢;在湿空气温度和冷面温度较低的情况下,表面特性对霜层生长的影响减弱;亲水表面具有较好的排液效果,其循环再结霜量最小。     

Interactions of xanthate with pyrite and galena surfaces in the presence and absence of oxygen

In this study, first-principles calculations were performed to investigate the interactions of hydrogen xanthate (HOCS₂⁻) with pyrite (1 0 0) and galena (1 0 0) surfaces. The calculation results suggest that strong chemisorption of HOCS₂⁻ occurs at Fe sites on the pyrite (1 0 0) surface, whereas its interaction at Pb sites on the galena (1 0 0) surface is weak. The interaction of xanthate with oxidized pyrite surface is weakened while the interaction of xanthate with oxidized galena surface is enhanced. The hydration of xanthate and mineral surfaces is discussed. Dixanthogen could be formed on the pyrite surface but not on the galena surface.     

Galvanic interaction of pyrite with Cu activated sphalerite and its effect on xanthate adsorption

In the presence of Cu ions, a packed bed electrochemical reactor (PBER) was employed to deliberately avoid or induce galvanic coupling between pyrite and Cu‐activated sphalerite. The effect of galvanic interaction on Cu ions uptake and xanthate adsorption were investigated. Solution chemistry and surface chemistry studies (ethylenediaminetetraacetic acid extraction and time of flight secondary ion mass spectrometry) have observed that when sphalerite and pyrite were galvanically coupled, Cu ions migrated from the pyrite surface to the surface of the sphalerite. Along with the marked decrease in the adsorption of Cu ions on pyrite, xanthate adsorption on the minerals also dramatically dropped. The pseudo‐adsorption rate constant for the minerals in the mixed mode is only 0.0583 s^?1, much less than that in the decoupled mode, which is 0.1368 s ^?1. This testing program shows that the galvanic coupling of minerals contributes to more copper transfer and Cu ions preferentially adsorbed by sphalerite rather than pyrite. This affects the pyrite surface and causes it to become xanthate unflavoured.     

Water flow enhancement in hydrophilic nanochannels

All published reports on fluid flow enhancement and water slippage are associated with hydrophobic surfaces, such as carbon nanotubes. Here, we investigate water flow in hydrophilic alumina nanochannels with diameters ranging from 20 nm to 100 nm. For the smallest channels tested, the water permeability is more than double than the theoretical prediction using the Hagen-Poiseuille equation. Though such an enhancement is significantly smaller than what has been measured in carbon nanotubes, it clearly shows that flow enhancement and water slippage occurs on hydrophilic surfaces as well, contrary to existing theoretical models. To the authors' knowledge, it is the first experimental demonstration of water slippage on hydrophilic surfaces. The results show the dependence of the flow enhancement on the surface chemistry, diameter and length of the nanochannel.     

A simple model for the calculation of entrainment in flotation

Theoretical and experimental studies have been performed to analyze the entrainment of both hydrophilic and hydrophobic particles in flotation. A new model is proposed for the entrainment based on the water recovery trend. Two sets of timed flotation experiments were carried out to validate the model. These experiments were realized with quartz and pyrite as the only mineral in the pulp and with various frother concentrations and pulp densities. The chemical conditions of the pulp were adjusted to float pyrite as hydrophobic and to depress quartz as hydrophilic mineral. The solids recovery for each size fraction and water recovery was measured in these experiments. The proposed empirical model equation was checked against experimental observations. It was observed that the model equation well represented the entrainment-water relationship. Since hydrophilic mineral recovery mainly depends on the entrainment, the data obtained from quartz only tests were first fitted to the entrainment equation. The fit for quartz data was found to be satisfactory. This shows that the proposed model could be used to define the behavior of hydrophilic particles in a batch flotation test. The same model was applied for pyrite only tests and contribution of entrainment to hydrophobic mineral recovery was calculated. The results provided accurate interpretation of hydrophobic mineral entrainment, which is difficult to directly measure.     

组合表面调控液滴特性强化蒸汽冷凝传热

制备了具有不同疏水区宽度和面积分率的疏水-亲水间隔规则排列的组合表面。观测常压蒸汽在组合表面上冷凝时疏水区液滴的特性(液滴移除方式和最大液滴半径),利用格子Boltzmann方法模拟组合表面上凝液的运动。考察疏水区、亲水区宽度和表面过冷度对组合表面强化蒸汽冷凝传热的影响。利用滴状-膜状组合传热模型分析组合表面蒸汽冷凝传热性能的影响因素,并与实验结果比较。发现疏水区液滴自发地向亲水区定向迁移,精细设计的组合表面可以实现蒸汽滴状冷凝传热的强化,实验中强化因子可达1.20。疏水区宽度约为0.55 mm时组合表面的传热性能最大。表面过冷度越大,组合表面强化传热的效果越差,模型分析与实验结果吻合良好。     

Cellular Behavior of Human Adipose-Derived Stem Cells on Wettable Gradient Polyethylene Surfaces

Appropriate surface wettability and roughness of biomaterials is an important factor in cell attachment and proliferation. In this study, we investigated the correlation between surface wettability and roughness, and biological response in human adipose-derived stem cells (hADSCs). We prepared wettable and rough gradient polyethylene (PE) surfaces by increasing the power of a radio frequency corona discharge apparatus with knife-type electrodes over a moving sample bed. The PE changed gradually from hydrophobic and smooth surfaces to hydrophilic (water contact angle, 90º to ~50º) and rough (80 to ~120 nm) surfaces as the power increased. We found that hADSCs adhered better to highly hydrophilic and rough surfaces and showed broadly stretched morphology compared with that on hydrophobic and smooth surfaces. The proliferation of hADSCs on hydrophilic and rough surfaces was also higher than that on hydrophobic and smooth surfaces. Furthermore, integrin beta 1 gene expression, an indicator of attachment, and heat shock protein 70 gene expression were high on hydrophobic and smooth surfaces. These results indicate that the cellular behavior of hADSCs on gradient surface depends on surface properties, wettability and roughness.     

Control over wettability of textured surfaces by electrospray deposition

Microtextured surfaces were prepared by electrospray deposition (ESD) from hydrophilic and hydrophobic acrylic resin solutions. The surface morphologies and topologies were characterized using scanning electron microscopy and laser profile microscopy, respectively. Wetting behaviors on the surfaces were characterized by contact angle and sliding angle measurements. The contact angle of the water droplet on the hydrophilic resin‐coated surfaces decreased with an increase in the surface roughness. On the other hand, the contact angle on the hydrophobic resin‐coated surfaces increased with an increase in the surface roughness. In addition, a patterned surface composed of aligned fibers by ESD showed anisotropy of both wetting and sliding behaviors. These results indicate that ESD is a useful method for designing a textured surfaces and controlling the surface wettability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3811–3817, 2007     

ADSORPTION OF ETHOXYLATED NONIONIC SURFACTANTS FROM SILOXANE-BASED SOLVENT AND AQUEOUS SYSTEMS: USE OF QCM AND MODEL POLYMERIC SURFACES

Adsorption behavior was quantified with pure ethoxylated nonionic surfactants onto different polymeric surfaces (hydrophilic cotton and hydrophobic polyester) and model hydrophilic gold surface. The polymer materials used for the study were characterized using SEM. The role of ethylene oxide group variation in surfactant-polymer interaction was established using pure surfactant with the same alkyl chain length but varying ethoxylate chain lengths. It was observed that surfactant with more ethylene oxide groups per molecule, being more hydrophilic, interacts favorably with cotton in the hydrophobic siloxane solvent environment. The adsorption of the pure surfactants on model gold surface from hydrophobic solvent and water was also established using the quartz crystal microbalance with dissipation monitoring (QCM-D) system. Effect of ethylene oxide chain length and surfactant concentration on the extent of adsorption was quantified. At the gold-water interface, the plateau adsorption for C₁₂ E₃ (15.9 × 10^?6 mole/m²) is about four times higher than for C₁₂E₈. An opposite trend was observed for adsorption of the surfactants on gold in the hydrophobic D5 environment. Information about thickness, adsorption and desorption kinetics, and structure of adsorbed layer was obtained from the QCM-D frequency-dissipation data. The study is an important contribution towards fundamental understanding of applications involving the use of ethoxylated nonionic surfactants.     

催化基底表面亲水改性对氢气催化氧化效率影响的密度泛函研究

催化剂表面亲疏水性改性是一种常见的调控手段,其对催化剂催化活性、选择性和稳定性有着重要的影响。以氢气催化氧化转化为水为研究对象,从分子水平出发,通过多尺度密度泛函理论（DFT）计算了催化剂在不同程度的表面亲水改性后对水和氢气的吸附作用,并研究了吸附对于反应效率的影响。结果表明,随着表面亲水性的增强,催化剂表面对水吸附越来越多,而受体积排斥效应影响,氢气的吸附量越来越少。而对于同一催化剂表面,增大水分子的均相密度量可促进氢气在表面的吸附。该理论结果不仅很好地解释了催化剂表面亲水性对于催化活性的影响,且为表界面反应的效率调控与强化提供了思路。     

The synergetic depression effect of KMnO4 and CMC on the depression of galena flotation

The mechanism of carboxymethyl cellulose (CMC) on the galena surface and the enhancement of KMnO₄ on the depression of CMC to galena were investigated by flotation test, surface adsorption experiments, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). Flotation test results indicated that the addition of KMnO₄ under alkaline condition significantly enhanced the depression effect of CMC on galena. Surface adsorption experiments of butyl xanthate (BX) and CMC demonstrated that the adsorption amount of BX decreased after CMC was added into the pulp. And the adsorption amount of CMC increased while BX decreased sharply when KMnO₄ was added into the pulp. After galena was treated with KMnO₄ and CMC, dim spots (oxidation sites) on the surface of galena were observed by SEM-EDS. Results showed the high contents of C and O on the oxidation sites. XPS results indicated that oxidation-reduction reaction occurred on the mineral surface, and PbS₂O₃ or Pb(OH)₂ was probably the main component of the oxidization sites. The CMC could be adsorbed on the oxidation sites by the hydrogen bond to form a hydrophilic membrane on the mineral surface lead to galena depression. All results showed that KMnO₄ could enhance the depression effect of CMC on galena.     

Investigation on the hysteretic force of droplet on hydrophilic and hydrophobic surface

表面上液滴欲移动时所表现出的滞后现象尚未在理论上得到完全解决,其中液滴所受到的滞后阻力的分析和计算是定量描述此滞后现象的关键问题之一。本文应用高速摄像,实验研究了亲/疏水表面上液滴的滞后阻力,并依据相应的实验数据对滞后阻力进行了分析和验证。结果表明：液滴在亲水和疏水表面上运动时所受到的滞后阻力分别与铺展功和黏附功相对应。滞后阻力反映了液滴在亲/疏水表面上出现滞后现象的本质,同时对于进一步研究接触角滞后提供了理论基础。     

选钼回水中铝离子对辉钼矿可浮性的影响机制

通过辉钼矿浮选实验、Zeta电位测试、Al3+溶液化学分析及X射线光电子能谱分析(XPS),研究了选钼回水中的Al3+对辉钼矿可浮性的影响及其作用机制. 结果表明,铝离子会恶化辉钼矿的浮选指标,并导致其表面Zeta电位显著偏移,表明辉钼矿表面有Al3+吸附;Al3+在溶液中主要以铝离子、羟基铝离子、氢氧化铝沉淀形式存在,后两者具有极强的极性,能吸附在辉钼矿活泼的“棱”上,铝离子与辉钼矿“棱”氧化生成的MoO42?反应生成钼酸铝沉淀;由于辉钼矿“棱”的面积比“面”的面积小很多,而铝离子主要吸附在“棱”上,因此铝元素含量不多,但其确实能吸附在辉钼矿表面,且既有物理吸附也有化学吸附.     

PVDF中空纤维换热管亲/疏水组合表面强化蒸汽冷凝传热

针对塑料换热管热导率低的问题,采用非溶剂致相分离法（NIPS）,通过控制铸膜液中磺化聚醚砜（SPES）添加量,制备出具有致密层/非致密层复合结构,外表面接触角分别为49.8°、78.1°的中空纤维表面亲水（PVDF/SPES）、表面疏水（PVDF）换热管,在非致密层内填充水,从而提高换热管导热性能。将单根的表面亲水、疏水换热管编织,在列管式塑料换热器壳程,利用两根换热管的外表面,构建蒸汽冷凝用亲/疏水组合表面,研究该表面上蒸汽冷凝传热强化效果。研究表明,较熔融拉伸法制备的致密PVDF换热管疏水表面,NIPS法制备的亲水表面、疏水表面及亲/疏水组合表面上的蒸汽冷凝总传热系数分别提高46.6%、56.5%、99.7%。可见,较单一的亲水或疏水表面而言,亲/疏水组合表面能够显著强化蒸汽冷凝传热性能。     

The effect of topography and wettability of biomaterials on platelet adhesion

In this study, the effect of surface topography and wettability on the adsorption of albumin, fibrinogen, and platelet was investigated. In this experiment, silicon substrate with hydrophobic treatment, which has a micron-scale pillar structure was used. The proteins used were bovine serum albumin (BSA) and bovine fibrinogen (BFg), and platelet used was from human blood. BSA was fluorescently labeled with fluorescein isothiocyanate and BFg was fluorescently labeled with rhodamine B isothiocyanate. The experiment was conducted under shear flow condition, just like human blood vessels flow. In this study, BSA was preferentially adsorbed on hydrophobic surface, however BFg was adsorbed more on the hydrophilic surface. Fewer platelets were adhered on the hydrophobic surface. The lowest fibrinogen adsorption amount and the lowest platelet activity was observed on surfaces with specific interspacing of 6–8 μm, and BSA adsorption peaks at the height of 12 μm.The results shows that the hydrophobic surface has good anti-thrombogenicity and blood compatibility. Moreover, a surface with the characteristic scale similar to the platelet size is capable of inbibiting platelet adhesion and activation.     

太阳能加热液滴在亲疏水表面"黏-滑"蒸发

实验研究了亲水和疏水表面上太阳能加热去离子水及金纳米流体液滴三相接触线动力学。在亲水和疏水表面滴加2μL去离子水和纳米流体液滴,用一定功率太阳能模拟器照射液滴使其蒸发,期间采用高速摄像机实时记录液滴在不同表面上的蒸发过程。由MATLAB程序处理图像得到液滴在不同表面上蒸发过程中接触角和接触圆直径的动态变化过程。发现液滴接触线在不同亲疏水表面上存在不同运动特性。去离子水液滴在亲水表面上常接触面积模式和常接触角模式依次控制蒸发过程。去离子水液滴在疏水表面上都呈现出“黏-滑”蒸发特性,即液滴先以常接触面积模式蒸发,之后接触线快速滑动,接触线固定后再以常接触面积模式蒸发,依次往复。纳米流体液滴在亲水表面上主要以常接触面积蒸发模式为主,在疏水表面上同样呈现“黏-滑”蒸发特性。从液滴表面能角度出发,对液滴接触线“钉扎”和“去钉扎”过程进行详尽分析,得出基底润湿性和纳米颗粒沉积是影响液滴接触线在表面上运动的重要因素。     

AFM measurements of hydrophobic forces between a polyethylene sphere and silanated silica plates- the significance of surface roughness

Recently, substantial research effort has been devoted to the study of non-DLVO forces between hydrophobic surfaces. However, the significance of surface roughness in the analysis of these hydrophobic attractive forces has not been given sufficient consideration and research is now in progress to attend to this issue. Fused silica plates covered with adsorbed octadecyltrichlorosilane (OTS) were characterized by water contact angle measurements and atomic force microscopy (AFM). Surfaces with different surface coverages and different contact angles were obtained by variation of the adsorption time. OTS formed patches on the silica surfaces, the lateral size and height of which depended on the adsorption time. Such surfaces exhibit differences in roughness at the sub-nanometer level. Using the AFM colloidal probe technique, forces between a polyethylene sphere and silanated silica surfaces were measured in water. Long-range attractive forces were found, usually referred to as hydrophobic forces. The resulting force vs. distance curves were fitted with a double exponential function. The magnitude of the short-range part of the force curves seems to correlate with water contact angles at silanated silica surfaces. On the other hand, the range of the long-range force correlates with the roughness of the silanated silica surface. These results with silanated silica surfaces were compared with the AFM results for polyethylene and graphite surfaces and on the basis of these experimental efforts, it appears that the nature of these hydrophobic attractive forces is related to surface roughness.     

Fibrin-free intraocular lens for hindering secondary cataract with UV-photon-induced photochemical surface modification

A fibrin-free intraocular lens (IOL) has been developed for hindering secondary cataract. Hydrophilic and hydrophobic micro-domains were alternately generated on the poly(methyl methacrylate) [PMMA] IOL surface with UV photon irradiation. The modified IOL was soaked in aqueous fibrin solution, and the fibrin adsorption was measured by infrared spectroscopy (FT-IR). The results show that the fibrin adsorption on the sample with hydrophilic groups increased, while that on the sample with hydrophobic groups decreased. Moreover, the fibrin adsorption on the sample surface with hydrophilic and hydrophobic micro-domains arranged alternately was reduced to one-fifth of that on the untreated sample.     

微通道内表面性质对其内流体流动特性的影响

通过对玻璃微通道内壁表面进行羟基化处理、溶胶-凝胶法纳米SiO2颗粒沉积以及疏水分子自组装等改性处理,制备得到了具有不同内壁表面润湿性和粗糙度的微通道;系统研究了微通道内表面性质对其内流体流动特性的影响。结果表明,在微通道内表面浸润性相同(同为亲水或疏水)时,粗糙表面会比光滑表面给微通道内的流体流动带来更大的阻力,而且流体流动推动力越大时其影响越大;当微通道内表面粗糙度相同时,亲水表面会比疏水表面给微通道内的流体流动带来更大的阻力,而且流体流动推动力越大时其影响越显著;相比之下,微通道内表面浸润性对其内流体流动的影响比其粗糙度的影响更大。研究结果可以为微流动系统或微流体机械的设计和应用提供指导。