Adhesion of blood platelets under flow to wettability gradient polyethylene surfaces made in a shielded gas plasma

Adhesion and activation of platelets are important steps in the thrombosis of blood after contact with a biomaterial surface and are governed, in part, by the wettability of the surface. Since most implanted devices are in contact with blood under flow conditions, it is important to study the effect of wettability of device surfaces on the behavior of platelets also under flow. To this end, wettability gradient polyethylene surfaces were prepared through glow discharge with partial shielding over a length of 5 cm, with advancing water contact angles varying from 95 to 45 degrees and a contact angle hysteresis of 30 degrees. The role of blood flow on the adhesion of platelets was examined by incubating these gradient surfaces in anticoagulated, whole human blood under static conditions or in blood under a flow of 10 or 40 ml/min through a 3 mm diameter circuit or for 5 or 15 min with either the hydrophobic or hydrophilic end upstream. Generally, more platelets adhered on the hydrophilic end of the wettability gradient than on the hydrophobic end, although the increment along the wettability gradient was dependent on both the flow conditions and direction. More platelets adhered under a flow of 10 ml/min than under static conditions, due to higher mass transport. Especially when the hydrophilic end was upstream, there was a more pronounced adhesion. This can be explained in terms of immediate platelet activation by shear stress imposed at the upstream end. During flow of 40 ml/min, platelet adhesion on an upstream hydrophilic end was less than on a downstream hydrophilic end. We conclude that platelets detach from the hydrophilic end at high shear stress due to the spherical form of adhered platelets. Platelets on the hydrophobic end could withstand detachment by strong, flat shaped platelet-material contact.     

基于润湿性梯度设计的单向导水/油多孔材料研究进展

近年来,具有独特的自发性液体运动的单向导水/油材料已成为研究热点。单向导水/油多孔材料是一种可用于雾水收集、油水分离、微流体传输以及功能织物等各种领域的新型材料。与普通的均匀润湿性多孔材料相比,具有单向液体传输特性的三维多孔材料通过表面和厚度方向的润湿性梯度精确设计,可以提供驱动力,促进液体的定向输送,提高液体传输效率,且能减少能源消耗。本文主要从化学梯度的调控、粗糙度梯度的构造、孔径梯度的设计这三种思路出发,按八种不同制备方法详细介绍了基于润湿性梯度的单向导水/油多孔材料的制备、输送液体的类型以及单向传输特性,同时概述了单向导水/油多孔材料在吸湿排汗纺织品、雾收集、油水分离等方面的实际应用,并提出了单向导水/油多孔材料在设计和使用方面所面临的挑战和未来发展前景。     

Comparison of fibroblast and nerve cells response on plasma treated poly (L‐lactide) surface

Plasma technique can easily be used to introduce desired functional groups or chains onto the surface of materials, and so it has a special application to improve the cell affinity of polymers surfaces. The purpose of this study is to elucidate the interaction between the cells and the surface of crystalline poly (L ‐lactide) (PLLA) samples, which were modified using a low‐temperature plasma treatment apparatus. The plasma treatments were carried out in the carbon dioxide (CO₂) gas. The results showed that the contact angle of the samples, which was plasma treated in CO₂ gas, decreased compared with that of the untreated samples. The hydrophilicity increased because of the introduction of oxygen‐containing functional groups onto the PLLA surfaces according to the spectroscopy for chemical analysis. High quantities of ? C? O groups, such as hydroxyl and carboxyl could be in corporate into the surface of PLLA. The surface wettability, topography, and chemistry of treated PLLA samples were characterized by contact angle measurement, scanning electron microscope (SEM), and ATR‐FTIR spectroscopy. The origin and plasma‐treated samples were used to investigate the interaction of two different types of cells namely, B65 glial nervous, and L929 fibroblast cells. The nervous cell response on the PLLA plasma treated in the CO₂ gas were significantly superior to that of the L929 fibroblast cells and untreated one. The surface modification technique used in this study may be applicable to tissue engineering for the improvement of nerve tissue compatibility of polymer and scaffold‐type substrates. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication of superamphiphobic-textured surfaces with reversibly switchable wettability

To realize switchable wettability for water and oils, we firstly design a facile approach to achieve superamphiphobic-textured surfaces that display the apparent contact angles greater than 150° and the sliding angles smaller than 10° for various liquids, such as water and hexadecane. Then, plasma treatment and surface fluorination were performed on the superamphiphobic surface. The tunability of the chemical composition, along with hierarchical rough surface structure, gave rise to reversibly switchable wettability between superamphiphobicity and superamphiphilicity. The wettability of the textured surface was demonstrated by visible experimental results and measurements. The reason of switchable wettability can be confirmed by X-ray photoelectron spectroscopy analysis. These results give a useful attempt in simultaneously and reversibly switching wettability for water and oils, which may have potential application in functional superamphiphobic materials.     

梯度润湿表面脉动热管传热性能的研究

为提高脉动热管水平方向的运行性能,本文通过控制化学刻蚀时间,制备出冷凝段到蒸发段接触角由83.8°至0°均匀变化的纳米草结构梯度润湿表面。并将此结构引入至6弯管板式脉动热管中,在不同充液率、加热功率以及运行方向下开展可视化和传热性能试验。试验结果表明,在竖直运行时,梯度润湿表面脉动热管相比于纯铜脉动热管展现出较好的传热性能。水平方向上,相较于纯铜脉动热管几乎完全烧干、无法启动的情况,梯度润湿表面由于附加的梯度润湿驱动力,促进了液体工质的回流,脉动热管成功启动。且汽液界面脉动振幅、脉动速度以及脉动热管的传热性能显著提高,充液率50%时热阻最多降低45%。     

Characterization of non-uniform wettability on flame-treated polypropylene-film surfaces

The flame treatment of polypropylene (PP) film involves the use of impinging, conical flames to oxidize the surface of the PP.Depending on treatment conditions, the PP film can be exposed to an inhomogeneous environment because of the conical shape of the flames. This environment can lead to cross-web variations, or 'lanes', in the wettability of the film. We have developed a simple method to quantify these non-uniformities using the information provided by the Wilhelmy plate technique of dynamic contact angle measurement. Both surface-averaged and spatially resolved surface-energy data can be obtained by this technique. In the case of our PP film, the spatial nonuniformities were found to be caused by variations in surface chemistry, not topography. These nonuniformities are not observed on untreated PP. Use of this method enables a quantitative evaluation of the effects of flame-treatment process variables on treatment uniformity.     

Polyethylene grafted maleic anhydride to improve wettability of liquid on polyethylene films

Blends of linear low density polyethylene (LLDPE) and LLDPE grafted maleic anhydride (LLDPE‐g‐MA) were prepared by melt mixing. The surface of cast films with different contents and types of maleated PE were characterized through contact angle and wetting tension measurements, as well as attenuated total reflection IR spectroscopy. The tensile properties and light transmission of extruded films, as well as the performance of these films compared with commercial “antifog” films, for greenhouses were determined. The carbonyl polar groups on the surface of LLDPE/LLDPE‐g‐MA blends increased, and the equilibrium contact angles of water and dimethylformamide decreased when the content of maleated PE increased. Films made with these blends showed a noticeable reduction in water drop formation as the MA content was increased and when using LLDPE‐g‐MA of lower molecular weight. The light transmission through these films under condensation was improved when using increased contents of MA, which promotes better wetting of the water on the surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1802–1808, 2001     

Fast photo-switched wettability and color of surfaces coated with polymer brushes containing spiropyran

An intelligent photo-responsive spiropyran (SP)-contained surface that combines reversible wettability conversion with photochromic behavior was prepared on etched silicon substrates by atom transfer radical polymerization. The heterocyclic ring cleavage of SP moieties under UV irradiation leads to the change of the surface wettability and color. Water contact angle (CA) of the prepared surfaces change from 138.8° ± 1.3° to 42.7° ± 1.7° after 5 min under 365 nm UV irradiation and recover to its original state after 20 min of visible light irradiation, accompanied by the color change between yellowish and purple. To our knowledge, this result is the highest and fastest CA variation reported for surfaces containing SPs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

障碍物阻塞率梯度对甲烷爆炸特性影响研究

通过自主设计并搭建小型实验平台,研究障碍物阻塞率梯度依次为0、0.05、0.1、0.15时,甲烷火焰传播过程的火焰结构变化、火焰前锋动力学以及压力演变。结果表明：阻塞率梯度为0和0.05的工况,经过障碍物后的火焰前锋会由模糊逐渐变得清晰,随后火焰前锋会向燃烧区凹陷;而阻塞率梯度为0.1和0.15工况的火焰在经过障碍物后,前端始终模糊,随后湍流燃烧加剧,迅速在整个管道爆燃,并无火焰前锋凹陷现象。阻塞率梯度对火焰瞬时速度影响较大,而对平均速度并无太大影响。随着阻塞率梯度从0增大到0.15,最大火焰速度会明显提升,而平均火焰速度却近似一致。此外,高阻塞率梯度的障碍物组有利于压力积聚,随着阻塞率梯度的增大,峰值超压也呈现规律性的增大,达到峰值超压所需的时间也相应延长。     

Study on the adhesion behaviour of oil droplets in water on solid surfaces with different wettability and inclination

Microscopic adhesion of oil droplets is a hot research topic within multiphase flow systems in the petrochemical field in recent years, and it is also the key to revealing the mechanism of oil droplet–wall interaction. In this paper, a high-speed camera was used to capture the dynamic process of oil droplets impacting stainless steel, polyethylene, brass, and other materials in water, deeply analyze the influence mechanism of material wettability, droplet size, and inclination on adhesion behaviour in this process, and draw the Re~θ_eq phase diagram. The experimental results show that properly enhancing the lipophilicity of the material can prolong the drainage time and effectively inhibit adhesion. Too much lipophilicity can dramatically shorten the drainage time instead, which easily leads to the rapid adhesion of oil droplets. An increase in droplet size can also prolong the drainage time; at Re ≥46.31, the excessive initial kinetic energy is consumed in the form of oil droplet rebound, which is not conducive to adhesion, and the more lipophilic the material is, the more significant the rebound effect. In addition, although an increase in the inclination can inhibit oil droplet bounce off, it also decreases the wall restraint to oil droplets, resulting in lateral and normal displacements, which greatly increases the drainage time. The findings can facilitate the understanding of oil droplet–wall interaction and provide a scientific basis for the design and development of efficient separation equipment and the optimization of the low-temperature gathering and transportation of high water-bearing crude oil.     

积雪草提取物对皮肤细胞生物学特征的影响

通过体外培养角质形成细胞和成纤维细胞,应用XTT方法和流式细胞仪比较研究积雪草苷和羟基积雪草苷对靶细胞增殖和细胞周期的影响。结果显示,积雪草苷和羟基积雪苷在质量浓度高达200μg/mL时未见任何细胞毒性;对人皮肤角质形成细胞和成纤维细胞有明显促进增殖和DNA合成作用(p<0 05);积雪草苷比羟基积雪草苷有更强的生物活性(p<0 05)。     

Effects of functional groups and surface roughness on interfacial shear strength in ultrahigh molecular weight polyethylene fiber/polyethylene system

Corona discharge treatment was conducted for ultrahigh molecular weight polyethylene (UHMWPE) fiber. The functional groups and surface roughness of the polyethylene fiber surface were determined by an X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The interfacial shear strength of UHMWPE fiber with HDPE film was determined by microbond pullout method. The interfacial shear strength increased by corona treatment. Then, the effect of the chemical and physical factors on the interfacial shear strength was discussed based on the results of multivariate regression analysis. The results indicated that the contribution of functional groups and surface roughness to the interfacial shear strength was expressed as 50 and 50%, respectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 243–249, 1999     

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.     

淋巴细胞增殖抑制因子的免疫生物学活性研究

以牛胸腺和猪胸腺为原料，利用饱和（NH4）2SO4沉淀、超滤和层析技术，获取淋巴细胞增殖抑制因子。提取物分子量在10KDa左右，对人T淋巴细胞增殖反应具有明显的抑制作用，平均抑制率达77．63±9．37％，对自然杀伤细胞的细胞毒活性无明显影响。提示所提取的淋巴细胞增殖抑制因子对T细胞增殖抑制具有相对特异性。     

Thermosensitive surface properties of polyethylene film with poly(N-isopropylacrylamide) chains prepared by corona discharge induced grafting

Polyethylene (PE) film was treated by corona discharge and then grafted with N-isopropylacrylamide (NIPAAm) for modification of the surface. The grafted amount was determined by gravimetry and the surface morphology was observed by using a scanning electron microscope. The surface analysis was carried out with a x-ray photoelectron spectroscopy and electron probe microanalysis. It was clarified that grafting was limited surface and there was no change of the surface morphology after grafting. The water absorption at various temperature under the absolute humidity (11.4 g/cm³) and the leakage of electrostatic charge from PE film were measured. PolyNIPAAm that was introduced onto PE surface has hydrophilic-hydrophobic transition properties at the 32°C in the atmospheric condition. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1773–1779, 1998     

Adsorption of bovine serum albumin onto glass powder surfaces coated with polyvinyl alcohol

The adsorption of bovine serum albumin (BSA) was carried out onto polyvinyl alcohol–coated glass powder surfaces. The adsorbed amount was about four times more than that on uncoated glass. The kinetics of the adsorption process was followed colorimetrically, and kinetic parameters, such as adsorption coefficient, rate constants for adsorption and desorption, diffusion constant, and penetration rate constant, were evaluated. The effects of experimental conditions, such as pH, presence of salts, addition of aliphatic alcohols, and variation in the dielectric constant of the medium, on the amount of adsorbed BSA were investigated. The effect of temperature on adsorption was also studied, and several thermodynamic parameters, such as standard free energy change (ΔG°), heat of reaction (ΔH°), and entropy change (ΔS°), were evaluated. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 933–940, 2000     

铵钒青铜基浓差流动电池的盐差发电性能研究

浓差流动电池依靠法拉第电极和存在浓度差的两股盐溶液之间可逆的反应,可将盐差能转化为电能;其与传统膜基盐差能提取技术相比具有成本低、寿命长和体积小等优点。然而已报道的浓差流动电池用电极需要预充电处理而且可能产生有毒离子。铵钒青铜是一种对环境友好的法拉第电极材料。它作为电极与普通滤膜组成浓差流动电池,在不需要预充电处理的前提下,平均输出功率密度高达194.3 mW·m^-2（20和500 m mol·L^-1的NaCl溶液）,相比于石墨烯水凝胶基盐差发电器件（141.4 mW·m^-2）提升了37%。此外,盐离子价态和尺寸对盐差发电性能存在一定的影响。铵钒青铜的引入,为设计浓差流动电池中的电极材料提供了新思路。     

液滴撞击不同浸润性壁面动态过程的数值模拟

采用VOF方法模拟了液滴以相同速度撞击到接触角分别为63°、90°、118°和160°的固体壁面上的形态演变过程。结果表明:固壁的亲憎水性对液滴撞击表面后形态的演化有较大影响,亲水壁面有利于液滴的铺展,在接触角为90°的壁面上液滴部分反弹,而当接触角为160°时,液滴完全反弹;当三相接触线开始回缩时,中心液体的表层部分在惯性力的作用下继续向铺展的液滴边缘聚集,导致近中心处液膜逐渐减薄至断裂,最终形成边缘较厚的液环;同时,液滴最大铺展系数随壁面接触角的增大而减小,达到最大铺展系数的时间也相应缩短。     

慢性粒细胞白血病树突状细胞对T细胞增殖作用的研究

目的　体外诱导慢性粒细胞白血病 (CML)患者外周血单个核细胞 (PBMCs)为树突状细胞 (DCs) ,并对其形态、表型及对T细胞刺激增殖作用进行研究。方法　利用GM CSF、IL 4、TNF α体外定向诱导生成树突状细胞 ,对所诱生的细胞进行细胞表型及形态检测 ,用D FISH方法检测所诱生DCs的白血病源性 ,应用MTT法检测所诱生的DCs刺激T细胞增殖的能力。结果　CML患者PBMCs在体外可诱导生成bcr/abl融合基因阳性的DCs(CMLDCs)。CMLDCs对自体T细胞有明显刺激增殖作用 ,而CML细胞无此作用。CMLDCs刺激同一异体T细胞增殖能力弱于正常DCs,但当培养体系中加入 30 0U/ml干扰素 α(IFN α)时可使其刺激能力接近正常DCs。结论　CMLDCs具有刺激自体及异体T细胞增殖的能力 ,但对异体T细胞的刺激作用弱于正常DCs,IFN α可提高CMLDCs刺激T细胞增殖能力