共查询到18条相似文献,搜索用时 629 毫秒
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基于面积差弹性模型, 用弛豫法探寻满足开口膜泡边界条件的欧拉-拉格朗日方程组的新解, 得到了双开口的哑铃形分支解, 并结合以前得到的单开口哑铃形及闭合哑铃形, 对它们之间的相变进行了深入的研究. 为了探究实验上是否可能发现这些形状, 与以往实验上观察到的较小约化弛豫面积差的杯形、管形、烟囱形开口形状的能量进行了比较, 发现这些新形状在较大的约化弛豫面积差值时, 在某些线张力区间比以往发现的形状能量更低. 另外为了对比, 本文对于实验上已知的杯形、管形、烟囱形及球形之间的相变行进行了探讨, 并对两者之间的不同特点进行了对比. 相似文献
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通过对Willmore区域外,特别是中等及较小约化体积下的形状及其演化进行深入细致的研究,发现在这一区域的形状要远比原有的猜测丰富,亏格g=2的膜泡会展现出比已有结果更多迷人的形状并出现新的膜泡相变分支.同时,数值计算的结果更加期待实验验证,从而为曲率模型的正确性提供有力支持. 相似文献
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利用倒置显微镜研究电制备巨囊泡, 并分析其形成和成长的动力学机理. 由于磷脂头部的电特性, 电场对水化的磷脂双层的静电力促使磷脂膜内双层之间分离. 在动力学的作用下, 双层两叶的不对称受力引发其弯曲、出芽、膨胀、封闭以及相互融合. 结果表明, 电场参数、干磷脂膜的均匀性、缓冲液以及温度等因素影响巨囊泡的粒径、形状和稳定性. 相似文献
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利用倒置显微镜研究电制备巨囊泡,并分析其形成和成长的动力学机理.由于磷脂头部的电特性,电场对水化的磷脂双层的静电力促使磷脂膜内双层之间分离.在动力学的作用下,双层两叶的不对称受力引发其弯曲、出芽、膨胀、封闭以及相互融合.结果表明,电场参数、干磷脂膜的均匀性、缓冲液以及温度等因素影响巨囊泡的粒径、形状和稳定性. 相似文献
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Based on the Canham-Helfrich free energy, we derive analytical expressions for the shapes of axisymmetric membranes consisting
of multiple domains. We give explicit equations for both closed vesicles and almost cylindrical tubes. Using these expressions,
we also find the shape of a tube attached to a spherical vesicle. The resulting shapes compare well to numerical data, and
our expressions can be used to easily determine membrane parameters from experimentally obtained shapes. 相似文献
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We present results on the stretching of single tubular vesicles in an elongation flow toward dumbbell shapes, and on their relaxation. A critical strain rate epsilonc exists; for strain rates epsilon相似文献
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We study the one-dimensional solution of the shape equation of bilayer membranes within the Helfrich spontaneous curvature model.The general integral of the cylindrical shape equation is obtained which gives a complete classification of the cylindrical surfaces corresponding to the shape equation.For closed vesicles,they are inward noduloids,outward noduloids,alternatively inward and outward noduloids and polygonal shapes.The curvature of the contours of the cross sections of these surfaces can be expressed in terms of elliptic functions of their arc lengths. 相似文献
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Linear polarization effects on laser drilling were investigated by the use of a picosecond laser system. It was observed that the exit shapes of stainless steel were placed perpendicular to the direction of polarization. According to theoretical analysis, the main factor that determines the exit hole shape is the difference between R s and R p. When this gap is large enough, the bulges on the exit hole will be easily observed. Inversely, when the gap is small, bulges can be barely spotted on the exit hole. This is further confirmed by comparative experiment and calculation conducted on a copper sheet. 相似文献
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《Journal of magnetism and magnetic materials》2003,265(3):269-273
The formation of three kinds of hard domains (HDs) at low bias field was studied experimentally. Low-bias-field method provides a simple way to produce the three kinds of HDs in different proportions. Also, the relationship between the shape of the multi-branched domains (MBDs) and the different kinds of domains was studied. Most branches of the MBDs correspond to the first kind of dumbbell domains or the second kind of dumbbell domains; in contrast, few branches of the MBDs correspond to the hard bubbles or soft bubbles. 相似文献
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Veronika Kralj-Iglič Blaž Babnik Dorit R. Gauger Sylvio May Aleš Iglič 《Journal of statistical physics》2006,125(3):723-748
Shapes of phospholipid vesicles that involve narrow neck(s) were studied theoretically. It is taken into account that phospholipid molecules are intrinsically anisotropic with respect to the membrane normal and that they exhibit quadrupolar orientational ordering according to the difference between the local principal membrane curvatures. Direct interactions between oriented molecules were considered within a linear approximation of the energy coupling with the deviatoric field. The equilibrium shapes of axisymmetric closed vesicles were studied by minimization of the free energy of the phospholipid bilayer membrane under relevant geometrical constraints. The variational problem was stated by a system of Euler-Lagrange differential equations that revealed a singularity in the derivative of the meridian curvature at points where the effect of the orientational ordering exactly counterbalances the effect of the isotropic bending. The system of Euler-Lagrange differential equations was solved numerically to yield consistently related equilibrium orientational distribution of the phospholipid molecules and vesicle shape. According to our estimation of the model constants the formation of the neck is promoted if direct interactions between the oriented molecules are taken into account. It was shown that the energy of the equilibrium shapes is considerably affected by the quadrupolar ordering of phospholipid molecules. 相似文献
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C. Barbetta A. Imparato J. -B. Fournier 《The European physical journal. E, Soft matter》2010,31(3):333-342
We calculate the stress tensor for a quasi-spherical vesicle and we thermally average it in order to obtain the actual, mechanical,
surface tension t \tau of the vesicle. Both closed and poked vesicles are considered. We recover our results for t \tau by differentiating the free energy with respect to the proper projected area. We show that t \tau may become negative well before the transition to oblate shapes and that it may reach quite large negative values in the
case of small vesicles. This implies that spherical vesicles may have an inner pressure lower than the outer one. 相似文献
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The canonical density matrix for a non-interacting electron gas bounded by a planar infinite barrier is calculated exactly by solving the Bloch equation for free particles. A closed expression describing the shape and size of the Fermi hole is thereby obtained. 相似文献