اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدSimple lattice model for biological gels
113
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We construct a three-dimensional lattice model for biological gels in which straight lines of bonds correspond to filamentous semi-flexible polymers and lattice sites, which are exactly four-fold coordinated, to crosslinks. With only stretching central forces between nearest neighbors, this lattice is sub-isostatic with an extensive number of zero modes; but all of its elastic constants are nonzero, and its elastic response is affine. Removal of bonds with probability $1-p$ leads to a lattice with average coordination number less than four and a distribution of polymer lengths. When bending forces are added, the diluted lattice exhibits a rigidity threshold at $p=p_b<1$ and crossover from bending-dominated nonaffine to stretching-dominated affine response between $p_b$ and $p=1$.
قيم البحث
اقرأ أيضاً
We study a lattice model of attractive colloids. It is exactly solvable on sparse random graphs. As the pressure and temperature are varied it reproduces many characteristic phenomena of liquids, glasses and colloidal systems such as ideal gel format
ion, liquid-glass phase coexistence, jamming, or the reentrance of the glass transition.
Following recent X-ray diffraction experiments by Wong, Li, and Safinya on biopolymer gels, we apply Onsager excluded volume theory to a nematic mixture of rigid rods and strong ``$pi/2$ cross-linkers obtaining a long-ranged, highly anisotropic deple
tion attraction between the linkers. This attraction leads to breakdown of the percolation theory for this class of gels, to breakdown of Onsagers second-order virial method, and to formation of heterogeneities in the form of raft-like ribbons.
The compressive yield stress of particle gels shows a highly nonlinear dependence on the packing fraction. We have studied continuous compression processes, and discussed the packing fraction dependence with the particle scale rearrangements. The 2D
simulation of uniaxial compression was applied to fractal networks, and the required compressive stresses were evaluated for a wide range of packing fractions that approached close packing. The compression acts to reduce the size of the characteristic structural entities (i.e. the correlation length of the structure). We observed three stages of compression: (I) elastic-dominant regime; (II) single-mode plastic regime, where the network strengths are determined by the typical length scale and the rolling mode; and (III) multi-mode plastic regime, where sliding mode and connection breaks are important. We also investigated the way of losing the fractal correlation under compression. It turns out that both fractal dimension $D_{mathrm{f}}$ and correlation length $xi$ start to change from the early stage of compression, which is different from the usual assumption in theoretical models.
We use molecular dynamics computer simulations to investigate the relaxation dynamics of a simple model for a colloidal gel at a low volume fraction. We find that due to the presence of the open spanning network this dynamics shows at low temperature
a non-trivial dependence on the wave-vector which is very different from the one observed in dense glass-forming liquids. At high wave vectors the relaxation is due to the fast cooperative motion of the branches of the gel network, whereas at low wave vectors the overall rearrangements of the heterogeneous structure produce the relaxation process.
We study the strain response to steady imposed stress in a spatially homogeneous, scalar model for shear thickening, in which the local rate of yielding Gamma(l) of mesoscopic `elastic elements is not monotonic in the local strain l. Despite this, th
e macroscopic, steady-state flow curve (stress vs. strain rate) is monotonic. However, for a broad class of Gamma(l), the response to steady stress is not in fact steady flow, but spontaneous oscillation. We discuss this finding in relation to other theoretical and experimental flow instabilities. Within the parameter ranges we studied, the model does not exhibit rheo-chaos.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
