摘要:

In order to study slow dynamics of lipid bilayers, neutron spin echo (NSE) experiments were carried out on the dilute lamellar phase in the DPPC/D2O/CaCl2system. From the NSE results, we estimated the bending modulus &kgr; of the bilayer using the theory presented by Zilman and Granek (Phys. Rev. Letters77(1996) 4788). The estimated values of &kgr; decrease monotonically with increasing temperature and with increasing the lamellar repeat distanced1. They depend strongly ond1thoughd1is longer than 500Å. We discuss validity of the theory for the analysis of the NSE results. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764082

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A bending modulus of surfactant monolayers in a microemulsion system composed of AOT, D2O and deuterated decane were investigated by means of neutron spin echo. In this system, a water‐in‐oil droplet structure at ambient temperature and pressure decomposes into two‐phases both with increasing temperature and pressure. However, the bending modulus slightly decreased with increasing temperature while it increased with increasing pressure. This behavior was explained in terms of a microscopic model proposed by Wu¨rger (Phys. Rev. Lett.85(2000) 337). It was confirmed that an increase of an interaction between hydrocarbon tails of AOT molecules with increasing pressure could be an origin of the pressure‐induced phase transition. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764083

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We study iron oxide nanoparticles stabilized by citrate ligands interacting with long linear poly(acrylamide) chains in the regime where the diluted chains are decorated by many smaller magnetic nanoparticles. The strength of adsorption of the particles onto polymer increases when the unbound citrate concentration decreases, as evidenced by the faster translational dynamics of the particle‐polymer complexes and the slower rotational dynamics of the nanoparticles. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764084

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We study the dynamics of concentrated ionic magnetic colloidal dispersions, which are constituted of &ggr; ‐Fe2O3nanoparticles dispersed in water, and stabilized with electrostatic interparticle repulsion, using magneto‐optical birefringence measurements. By gradually increasing the volume fraction &Fgr; of the particles at constant ionic strength in the repulsive region of the phase diagram, we observe a dramatic increase of the characteristic time associated with the rotation of the particles that we induce by applying a field pulse. This increase is reminiscent of the divergence of the relaxation time observed at the approach of a glass transition and confirms the existence of a glassy phase in these magnetic colloids. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764085

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We present a numerical study of a shear‐induced solid‐fluid transition in wet granular matter in order to show the self‐organized critical behavior close to the transition point. The continuous time simulation is based on a simple model considering both the cohesive forces induced by the adsorbed liquid amount and the repulsive forces due to the hard core interaction of the granules. Dissipation is assumed to be entirely due to the hysteretic character of the cohesive forces. The aim of our analysis concerns the crossover from a solid like behavior to a mobile ergodic state under the influence of an external force fieldFexceeding the critical forceFc. Diffusion coefficients, dissipation and kinetic order parameters can be expressed as characteristic scaling laws. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764086

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Conformations of a single semiflexible polymer chain dissolved in a low molecular weight liquid crystalline solvent (nematogen) are examined by using a mean field theory. We takes into account a stiffness and partial orientational ordering of the polymer. As a result of an anisotropic coupling between the polymer and nematogen, we predict a discontinuous (or continuous) phase transition from a condensed‐rodlike conformation to a swollen‐one of the polymer chain, depending on the stiffness of the polymer. We also study a single polymer chain confined in a smectic phase. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764087

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A phenomenological model for the unbinding transition of multicomponent fluid membranes is proposed, where the unbinding transition is described using a theory analogous to Flory‐Huggins theory for polymers. The coupling between the lateral phase separation of inclusion molecules and the membrane‐substrate potential provides a rich phase behavior. Our model describes the first‐order nature of the unbinding transition in multicomponent membranes as was observed in a recent experiment. In particular, we predict different scenarios of phase coexistence between bound and unbound membrane states. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764088

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We have derived the effect of steady heat flux on the rate of chemical reaction based on the line‐of‐centers model using the explicit velocity distribution function of the steady‐state Boltzmann equation for hard‐sphere molecules to second order. We have found that the second‐order velocity distribution function plays an essential role for the calculation of it. This indicates the significance of the second‐order coefficients in the solution of the steady‐state Boltzmann equation as terms which reflect the local nonequilibrium effect. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764089

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Director of nematic liquid crystal fluctuate with relaxation time which is infinity at long wave length. We calculated effect of fluctuation on transmitted light along layered nematic medium. We found fluctuation of retardation and distance transmitted is expressed by a type of Langevin equation. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764090

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We investigate the dynamics of phase separation in two‐component fluid membranes confined between parallel and rigid bounding plates. Through numerical simulation, we find a considerably slow coarsening of the order parameter field within the time region we studied. In particular, a microphase separation is obtained as an equilibrium phase for sufficiently large values of the elastic coupling, which is in agreement with the previous mean‐field analysis. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764091

出版商:AIP    

年代:1904

数据来源: AIP