共查询到10条相似文献,搜索用时 125 毫秒
1.
H. Schiessel 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(3):373-380
We investigate the bending of flexible charged membranes due to the presence of rigid rodlike macroions in the framework of
the Debye-Hückel approximation. When the macroions are fixed in space at some distance from the bilayer the membrane bends
towards them; we calculate the exact deformation profile. On the other hand a macroion which is adsorbed on the membrane causes
a deflection of the bilayer. Finally, we consider swollen lamellar polyanion/charged-lipid complexes where the macroions are
intercalated between charged lipid bilayers. We predict the occurrence of a double adsorption (pinching effect) of the macroion
for sufficiently flexible membranes.
Received: 9 February 1998 / Revised: 9 June 1998 / Accepted: 2 July 1998 相似文献
2.
R. Menes N. Grønbech-Jensen P.A. Pincus 《The European physical journal. E, Soft matter》2000,1(4):345-349
Using both theoretical modeling and computer simulations we study a model system for DNA interactions in the vicinity of charged
membranes. We focus on the polarization of the mobile charges in the membranes due to the nearby charged rods (DNA) and the
resulting screening of their fields and inter-rod interactions. We find, both within a Debye-Hückel model and in Brownian
dynamics simulations, that the confinement of the mobile charges to the surface leads to a qualitative reduction in their
ability to screen the charged rods to the degree that the fields and resulting interactions are not finite-ranged as in systems
including a bulk salt concentration, but rather decay algebraically and the screening effect is more like an effective increase
in the multipole moment of the charged rod.
Received 28 September 1999 相似文献
3.
Macdonald PM Crowell KJ Franzin CM Mitrakos P Semchyschyn D 《Solid state nuclear magnetic resonance》2000,16(1-2):21-36
2H NMR studies of polyelectrolyte-induced domain formation in lipid bilayer membranes are reviewed. The 2H NMR spectrum of choline-deuterated phosphatidylcholine (PC) reports on any and all sources of lipid bilayer surface charge, since these produce a conformation change in the choline head group of PC, manifest as a change in the 2H NMR quadrupolar splitting. In addition, homogeneous and inhomogeneous surface charge distributions are differentiated. Adding polyelectrolytes to lipid bilayers consisting of mixtures of oppositely charged and zwitterionic lipids produces 2H NMR spectra which are superpositions of two Pake sub-spectra: one corresponding to a polyelectrolyte-bound lipid population and the other to a polyelectrolyte-free lipid population. Quantitative analysis of the quadrupolar splittings and spectral intensities of the two sub-spectra indicate that the polyelectrolyte-bound populations is enriched with oppositely charged lipid, while the polyelectrolyte-free lipid population is correspondingly depleted. The same domain-segregation effect is produced whether cationic polyelectrolytes are added to anionic lipid bilayers or anionic polyelectrolytes are added to cationic lipid bilayers. The 2H NMR spectra permit a complete characterization of domain composition and size. The anion:cation ratio within the domains is always stoichiometric, as expected for a process driven by Coulombic interactions. The zwitterionic lipid content of the domains is always statistical, reflecting the systems tendency to minimize the entropic cost of demixing charged lipids into domains. Domain formation is observed even with rather short polyelectrolytes, suggesting that individual polyelectrolyte chains aggregate at the surface to form "superdomains". Overall, the polyelectrolyte bound at the lipid bilayer surface appears to lie flat along the surface and to be essentially immobilized through its multiple electrostatic contacts. 相似文献
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5.
本文将等离子体核聚变反应截面研究中利用等离子体环境涨落进行修正了的Debye-Hückel屏蔽势推广到计算等离子体中辐射离子束缚态的能级结构. 通过Tsallis参数q的变化,在等离子体辐射离子束缚态能级结构的计算中加入等离子体参数涨落的平均效应,即,等离子体动力学. 具体给出了利用修正的Debye-Hückel屏蔽势对类氦铝束缚态能级结构的计算结果. 结果表明基于这种修正的屏蔽势,自由电子的极化分布具有和线性Debye-Hückel屏蔽势不同的结构. 这种通过等离子体涨落分布对屏蔽势函数进
关键词:
等离子体中的原子结构
等离子体环境涨落
修正了的Debye-Hückel屏蔽势 相似文献
6.
We use large-scale Monte Carlo simulations to test scaling theories for the electrostatic persistence length l
e of isolated, uniformly charged polymers with Debye-Hückel intrachain interactions in the limit where the screening length
κ-1 exceeds the intrinsic persistence length of the chains. Our simulations cover a significantly larger part of the parameter
space than previous studies. We observe no significant deviations from the prediction l
e∝κ-2 by Khokhlov and Khachaturian which is based on applying the Odijk-Skolnick-Fixman theories of electrostatic bending rigidity
and electrostatically excluded volume to the stretched de Gennes-Pincus-Velasco-Brochard polyelectrolyte blob chain. A linear
or sublinear dependence of the persistence length on the screening length can be ruled out. We show that previous results
pointing into this direction are due to a combination of excluded-volume and finite chain length effects. The paper emphasizes
the role of scaling arguments in the development of useful representations for experimental and simulation data.
Received 12 February 2002 相似文献
7.
L. Belloni M. Olvera de la Cruz M. Delsanti J. P. Dalbiez O. Spalla M. Drifford 《Il Nuovo Cimento D》1994,16(7):727-736
Summary A queous solutions of highly charged flexible polyelectrolytes phase separate in the presence of multivalent counterions.
We present a theoretical model which explains this behavior in terms of electrostatic bridging between monomers via the condensed
counterions. The ?Polymer Reference Interaction Site Model? with the Debye-Hückel closure (equivalent to the ?Random Phase
Approximation?) is sufficient to understand the crucial role of the valency of the counterions, to predict a demixion above
a given valency and a redissolution of the precipitate in excess of added salt. The model successfully reproduces the different
experimental phase diagrams of polystyrene sulfonate suspensions with different added electrolytes.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
8.
Jancovici B 《The European physical journal. E, Soft matter》2006,19(1):1-4
A system of three electrolytes separated by two parallel planes is considered.
Each region is described by a dielectric constant and a Coulomb fluid in the
Debye-Hückel regime. In their book Dispersion Forces, Mahanty and Ninham
have given the van der Waals free energy of this system. We rederive this free
energy by a different method, using linear response theory and the
electrostatic Maxwell stress tensor for obtaining the dispersion force. 相似文献
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10.
蜂毒肽非特异性地靶向杀伤细菌具有重要的生物医学应用前景. 利用荧光光谱与荧光显微考察了蜂毒肽与单组分、多组分磷脂膜的作用机制. 发现对于不同电性与相态的磷脂膜, 肽-膜作用呈现为稳定桶板型孔、非稳U型孔及变薄裂解等多种机制, 具有显著不同的内含物泄露效率. 多组分磷脂囊泡的泄露实验表明, 泄露由肽亲和性较强的磷脂组分决定. 相较于凝胶相磷脂, 蜂毒肽与液相磷脂的亲和性强, 凝胶-液相混合囊泡与纯液相磷脂囊泡的泄露性质相近; 相较于双电性磷脂, 蜂毒肽与负电性磷脂的亲和性强, 双电-负电混合囊泡与纯负电磷脂囊泡的泄露性质相近. 研究深化了多肽与多组分生物膜作用机制的理解. 相似文献