Bio-template Synthesis of Spirulina/α-Fe2O3 Composite with Improved Surface Wettability

Bio-template method has recently attracted much attention because of its prominent advantages in obtai-ning morphology controlled materials with structural specificity, complexity and their unique functions. The bio-template method combining with electrochemical deposition was employed to synthesize spirulina/hematite composite microstructures using native spirulina as template. A great amount of hematite(α-Fe₂O₃) nanoparticles can be formed and deposited onto the spirulina, resulting in a robust and pseudo-homogeneous surface. And the spirulina/α-Fe₂O₃ composite exhibits an improved surface wettability due to its helical morphology. This facile strategy may open new horizons in the field of replicating specific biological structures for functional materials in other potential applications.     

液滴在不同润湿性表面上蒸发时的动力学特性

基于润滑理论,采用滑移边界条件建立了二维液滴厚度的演化模型和移动接触线动力学模型,利用数值计算方法模拟了均匀加热基底上固着液滴蒸发时的动力学特性,分析了液-气、固-气和液-固界面张力温度敏感性对壁面润湿性和液滴动态特性的影响.结果表明,液滴的运动过程受毛细力、重力、热毛细力和蒸发的影响,重力对液滴铺展起促进作用,而毛细力、热毛细力则起抑制作用;通过改变界面张力温度敏感性系数,可使液滴蒸发过程中的接触线呈现处于钉扎或部分钉扎模式,且接触线钉扎模式下的液滴存续时间低于部分钉扎模式;提高液-气与液-固界面张力温度敏感系数均可改善壁面润湿性能,加快液滴铺展速率;而增大固-气界面张力温度敏感系数则导致壁面润湿性能恶化、延缓液滴铺展过程;通过改变固-气界面张力温度敏感系数更有利于调控处于蒸发状态下的液滴运动.     

基于各向异性表面的液滴驱动

驱动液滴实现各种动态行为在生物医学、微流控、痕量检测等领域具有重要应用。液滴的驱动主要依赖于对液滴不同位置受力的调节。具有浸润性差异或结构差异的各向异性表面,在对液滴进行驱动时具有操作简便、节约能源等优势,逐渐成为液滴操控领域的研究热点之一。本文结合本课题组的研究工作,对近年来利用各向异性表面驱动液滴的相关研究进行了综述。首先,分析了各向异性表面驱动液滴的基本原理。依据制备方法的不同,将各向异性表面分为浸润性各向异性表面、结构各向异性表面和协同各向异性表面三类,分别归纳了其常见制备方法和在液滴驱动领域的主要应用。最后,本文对各向异性表面驱动液滴的局限性和发展方向进行了总结和展望。     

三相界面电催化二氧化碳还原研究进展

电催化二氧化碳还原是能源化学及催化科学的研究重点与难点. 气-固-液三相界面模型作为物理化学中的基本概念, 近年来被越来越多地应用于电催化二氧化碳还原反应的研究, 其相比于传统固-液两相体系表现出了诸多优点. 本综述阐述了三相界面电催化二氧化碳还原研究进展, 对三相界面电催化体系进行分类及原理探究. 再具体到二氧化碳还原反应, 讨论其水下超亲气体系以及气体扩散层体系的结构特性及电催化性质, 并对包括反应物界面扩散及界面浸润性等影响因素进行了系统分析. 最后对当前研究存在的问题及今后电催化二氧化碳还原领域的发展方向进行了总结与展望.     

Synthesis of Poly(L‐lactide) with One Terminal D‐Glucose Residue and Wettability of Its Film Surface

To develop the new‐type poly(L ‐lactide)‐based biomedical material having a wettable surface, the synthesis of poly(L ‐lactide) with one terminal D ‐glucose residue was investigated. After the hydroxyl group at 1‐C of α‐tetrabenzyl glucose, α‐Glc(Bzl)₄, was converted to the corresponding potassium alkoxide by using potassium tert‐butoxide, L ‐lactide (L ‐LA) was polymerized in the presence of α‐Glc(Bzl)₄‐OK as an initiator in tetrahydrofuran at room temperature to prepare α‐Glc(Bzl)₄‐polyLA. Subsequently, the removal of O‐protecting benzyl groups in the terminal α‐Glc(Bzl)₄ residue was carried out by hydrogenolysis with Pd/C to obtain the objective D ‐glucose‐end‐capped polyLA, α‐Glc‐polyLA. The wettability of surface of the α‐Glc‐polyLA material is discussed using the difference of the dynamic contact angle between a α‐Glc‐polyLA/homopolyLA blend film and a film of the polyLA homopolymer.     

基于水平集方法的低渗砂岩数字岩心气水两相渗流模拟

低渗致密砂岩气藏孔喉结构复杂,气水流动及分布规律表征难,常规岩心实验精细刻画困难。基于真实低渗砂岩岩心,利用Micro-CT扫描技术构建储层三维数字岩心,提取连通孔隙结构并建立非结构化四面体网格模型。结合水平集法与N-S方程,建立气水两相流数学模型并利用有限元方法进行求解,研究低渗砂岩气水两相流动中的水驱气过程、残余气分布特征、岩石润湿性对两相流的影响以及并联通道中的窜流特征。结果表明：利用水平集方法能清晰地观察到气水两相分布特征与驱替前缘的运移规律;岩石润湿性对两相流过程影响较大,水湿条件下采出程度更高;并联通道中的窜流现象明显,大通道中水相优先突破并形成优势流动通道,狭小通道中的流动受毛管现象影响,存在较大的附加阻力。     

Crystallization Control of Molten Ba(B0.9Al0.1)2O4 from Supercooled Pendant Drop

Crystallization process of molten Ba(B_0.9Al_0.1)₂O₄ from supercooled pendant drop was investigated on a viewpoint of a supercooling and a solid phase formation. Molten pendant drop was crystallized by a rod touching at an crystallization temperature under an adequate degree of supercooling. Three kinds of rods were used. Each rod was made of Pt, hBN and graphite which had different wettability to the molten drop. There were three kinds of phases on a solid Ba(B_0.9Al_0.1)₂O₄, such as a high temperature crystal phase, a low temperature crystal phase and a glass phase. All phases could be formed by the present method.