基于超临界流体技术制备葡萄糖脂质体的实验研究

脂质体由于其特殊的结构和性能,是一种很有发展潜力的药物载体,在医药和化妆品等行业具有广阔的应用前景。超临界逆向蒸发法是用超临界流体代替有机溶剂制备脂质体的方法,具有对水溶性药物脂质体制备过程简单、包覆率高等特点。以葡萄糖为模型药物,利用该方法制备出了葡萄糖脂质体,并详细考察了不同工艺条件对脂质体粒径和包覆率的影响。结果表明:用超临界逆向蒸发法可成功地制备出最小粒径为290nm、包覆率最高可达41.3%的葡萄糖脂质体。压力、温度和平衡时间对粒径和包覆率都有较大的影响。压力在10~30MPa时,随压力的增加,脂质体粒径显著减小至某一值后,基本趋于稳定,而包覆率逐渐增加,达到25.7%~27.5%,随后包覆率逐渐减小;温度在35~65℃时,随温度的增加粒径显著减小至最小值,然后逐渐增大,而包覆率一直增大,最高可达41.3%;平衡时间在15~45min时,随平衡时间的增加,粒径相对稳定,而包覆率显著增加,超过45min之后,粒径显著增加,包覆率显著下降。     

Pressure dissociation of dense hydrogen

The self-consistent fluid variational model （SFVM） has been used to describe the pressure dissociation of dense hydrogen at high temperatures. This paper focuses on a mixture of hydrogen atoms and molecules and is devoted to the study of the phenomenon of pressure dissociation at finite temperatures. The equation of state and dissociation degree have been calculated from the free energy functions in the range of temperature 2000-10,000K and density 0.02-1.0g/cm^3, which can be compared with other approaches and experiments. The pressure dissociation is found to occur in higher density range, while temperature dissociation is a more gradual effect.     

低温气液两相流数值计算

低温工质两相流动在很多场合都存在,研究深冷剂在两相流动时参数的分布有着很重要的作用.文中采用一维均相流模型对液氮循环流动过程进行稳态数值模拟,得到了循环流动过程中液氮含汽率、压力和温度沿管程方向的分布情况,并对由于不同回路条件引起的不同结果进行了分析.     

On the boundary slip of fluid flow

For hundreds of years, in all the textbooks of classical fluid mechanics and lubrica- tion mechanics it is assumed that there was no wall slip (boundary slip) at a liquid-solid interface, i.e. no relative motion between liquid and solid at the interface. This is the no-slip boundary condition. It has been widely applied to engineering and experiments and to almost all the rheology or viscosity measurements of fluids. Rheology is one of the most important bases for fluid mechanics and lubricati…     

HCCB-DEMO氦冷固态包层热工水力计算及分析

根据这几年HCCB-DEMO包层技术的发展,对原氦冷固态氚增殖包层进行相应设计改进。利用三维有限元软件CFX对该改进设计进行了热工水力学计算及分析。分析模型包括：第一壁,增殖单元,筋板以及三者集成模型。结果表明：各子部件在单独分析的情况下,材料最高温度低于设计要求限值;冷却剂进出口温度为300/500°C,满足设计需求。同时对比分析了集成计算及单独计算的结果,得出第一壁与铍球床之间的相互热作用较大,铍球床材料最大温度会高于设计限值。针对经集成计算后发现的问题,未来将对氦冷固态包层的设计进行进一步的优化。     

Dual solutions in boundary layer flow of a moving fluid over a moving permeable surface in presence of prescribed surface temperature and thermal radiation

An analysis of the heat transfer for a boundary layer forced convective flow past a moving permeable flat surface parallel to a moving fluid is presented. Prescribed surface temperature at the boundary is considered. A thermal radiation term in the energy equation is considered. The similarity solutions for the problem are obtained and the reduced ordinary differential equations are solved numerically. To support the validity of the numerical results, a comparison is made with the available results for some particular cases of this study. Dual solutions exist when the surface and the fluid move in the opposite directions.     

Studying effect of MHD on thin films of a micropolar fluid

This paper deals with the study of the effect of MHD on thin films of a micropolar fluid. These thin films are considered for three different geometries, namely: (i) flow down an inclined plane, (ii) flow on a moving belt and (iii) flow down a vertical cylinder. The transformed boundary layer governing equations of a micropolar fluid and the resulting system of coupled non-linear ordinary differential equations are solved numerically by using shooting method. Numerical results were presented for velocity and micro-rotation profiles within the boundary layer for different parameters of the problem including micropolar fluid parameters, magnetic field parameter, etc., which are also discussed numerically and illustrated graphically.     

夹套冰温库内流场的数值模拟

随着计算机技术的飞速发展,计算流体力学(CFD)越来越广泛地应用于各个领域。通过CFD对复杂流动问题进行研究,能够较精确地反映流场的流动情况。利用CFD技术对夹套冰温库内的流场进行了稳态数值模拟,分析了夹套冰温库内流场的分布情况,讨论了该库体结构下不同送风速度对库内流场均匀性的影响。研究表明,具有夹套结构的冰温库,库内流场分布均匀,采用顶部静压箱送风,底部四周回风的送回风方式,能够使库内形成自上而下的均匀活塞流,不同送风速度对冰温库内流场的影响很小。研究结果证明数值模拟能较好地反映现实情况。     

Vibro-acoustic behaviour of laminated double glazing enclosing a viscothermal fluid cavity

This paper presents a new numerical model to investigate the vibro-acoustic behaviour of two laminated glass plates enclosing a thin viscothermal fluid cavity. The aim of this work is to develop an original five layer (two skins plies, two adhesive films and a core ply) laminated plate finite element by mixing Kirchhoff and Mindlin plate’s theory. The formulation is based on the theory that accounts for the transverse shear in the adhesive films and in the core. The acousto-elastic model is established in dimensionless appropriate form including the effects of viscosity and thermal conductivity of fluid and by taking into account the fluid-structure interaction. The discretization of the energy functional by finite element method gives after minimisation a symmetrical coupled matrix system in which the acoustic matrices are frequency dependent. Therefore, an iterative procedure is derived to determine the eigenmodes of the coupled system. The modal approach is adopted to determine the vibro-acoustic system’s response. Then, the validation of the new laminate finite element model is achieved by comparing the sandwich plate results against data obtained from literature. Subsequently, predicted responses, such as the vibration transmissibility and the transmission loss of the coupled system, for a given laminated double glazing under an imposed homogeneous pressure are presented and discussed. Numerical results show the importance of both lamination and viscothermal fluid effects on double glazing vibro-acoustic behaviour.     

超临界流体Rayleigh-Bénard对流的数值模拟研究

物质气液临界点附近热物理性质发生剧烈变化,会出现一种对热力学平衡有显著加速作用的热声活塞效应。而在长时间尺度上,因重力作用而产生的Rayleigh-Bénard对流在活塞效应的影响下,其表现出来的物理特性与普通流体相比存在较大的差异。我们通过SIMPLE方法对超临界氮在不同临界距离下的自然对流发生过程进行数值模拟,结果显示当流体热力学状态接近临界点时,对流作用的发生取决于边界层内热羽流的形成,并且具有明显的湍流特征,而随着离开临界点的距离加大,流场的形成逐渐过渡到一般可压缩流体的情形。