scholarly journals Relative contributions of chain density and topology to the elasticity of two-dimensional polymer networks

Soft Matter ◽  
2019 ◽  
Vol 15 (28) ◽  
pp. 5703-5713 ◽  
Author(s):  
Ghadeer Alamé ◽  
Laurence Brassart
Keyword(s):  
Polymer Networks ◽  
Random Networks ◽  
Two Dimensional ◽  
And Topology ◽  
Discrete Networks ◽  
Effects Of Density

Discrete networks simulations are conducted to decorrelate the effects of density and topology on the elasticity of near-ideal random networks.

Design and Synthesis of Two-Dimensional Covalent Organic Frameworks with Four-Arm Cores: Prediction of Remarkable Ambipolar Charge-Transport Properties

2019 ◽  
Author(s):  
Simil Thomas ◽  
Hong Li ◽  
Raghunath R. Dasari ◽  
Austin Evans ◽  
William Dichtel ◽  
...  
Keyword(s):  
Charge Transport ◽  
Organic Semiconductors ◽  
Density Functional ◽  
Polymer Networks ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
X Ray Diffraction ◽  
Zinc Porphyrin ◽  
Design And Synthesis ◽  
Predicted Values

<p>We have considered three two-dimensional (2D) π-conjugated polymer networks (i.e., covalent organic frameworks, COFs) materials based on pyrene, porphyrin, and zinc-porphyrin cores connected <i>via</i> diacetylenic linkers. Their electronic structures, investigated at the density functional theory global-hybrid level, are indicative of valence and conduction bands that have large widths, ranging between 1 and 2 eV. Using a molecular approach to derive the electronic couplings between adjacent core units and the electron-vibration couplings, the three π-conjugated 2D COFs are predicted to have ambipolar charge-transport characteristics with electron and hole mobilities in the range of 65-95 cm<sup>2</sup>V<sup>-1</sup>s<sup>-1</sup>. Such predicted values rank these 2D COFs among the highest-mobility organic semiconductors. In addition, we have synthesized the zinc-porphyrin based 2D COF and carried out structural characterization via powder X-ray diffraction and surface area analysis, which demonstrates the feasability of these electroactive networks.</p>

scholarly journals Mechanical origin of martensite-like structures in two-dimensional ReS2

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Lingli Huang ◽  
Fangyuan Zheng ◽  
Honglin Chen ◽  
Quoc Huy Thi ◽  
Xin Chen ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Two Dimensional ◽  
Domain Formation ◽  
Domain Structures ◽  
And Topology ◽  
Two Dimensional Materials ◽  
Small Lattice ◽  
Properties Of Materials ◽  
Potential Use ◽  
Diffusionless Transformation

AbstractMartensite is a needle-shaped microstructure formed by a rapid, diffusionless transformation and significantly affects the mechanical properties of materials. Here, in two-dimensional ReS2 we show that martensite-like domain structures can form via a diffusionless transformation, involving small lattice deformations. By analyzing the strain distribution and topology of the as-grown chemical vapor deposition samples, we find that cooling-induced strain at the ReS2/substrate interface is responsible for the mechanical loading and is essential for martensite-like domain formation. Meanwhile, the effect of cooling rate, flake size and substrate on the microstructures revealed the mechanical origin of the transformation. The strain-induced lattice reconstructions are rationalized and possibly lead to ferroelastic effects. In view of the strong anisotropy in electronic and optical properties in two dimensional materials like ReS2, opportunities exist for strain-correlated micro/nanostructure engineering, which has potential use in next-generation strain-tunable devices.

scholarly journals Emergent orientation selectivity from random networks in mouse visual cortex

2018 ◽  
Author(s):  
J.J. Pattadkal ◽  
G. Mato ◽  
C. van Vreeswijk ◽  
N. J. Priebe ◽  
D. Hansel
Keyword(s):  
Visual Cortex ◽  
Calcium Imaging ◽  
Receptive Fields ◽  
Orientation Selectivity ◽  
Random Networks ◽  
Two Dimensional ◽  
V1 Neurons ◽  
Mouse Visual Cortex ◽  
Whole Cell Recordings ◽  
Random Connectivity

SummaryWe study the connectivity principles underlying the emergence of orientation selectivity in primary visual cortex (V1) of mammals lacking an orientation map. We present a computational model in which random connectivity gives rise to orientation selectivity that matches experimental observations. It predicts that mouse V1 neurons should exhibit intricate receptive fields in the two-dimensional frequency domain, causing shift in orientation preferences with spatial frequency. We find evidence for these features in mouse V1 using calcium imaging and intracellular whole cell recordings.

scholarly journals Quantum gravity as a multitrace matrix model

2017 ◽  
Vol 32 (31) ◽  
pp. 1750180
Author(s):  
Badis Ydri ◽  
Cherine Soudani ◽  
Ahlam Rouag
Keyword(s):  
Quantum Gravity ◽  
Matrix Models ◽  
Large Class ◽  
Matrix Model ◽  
Two Dimensions ◽  
Two Dimensional ◽  
Topology Change ◽  
New Model ◽  
And Topology ◽  
Emergent Geometry

We present a new model of quantum gravity as a theory of random geometries given explicitly in terms of a multitrace matrix model. This is a generalization of the usual discretized random surfaces of two-dimensional quantum gravity which works away from two dimensions and captures a large class of spaces admitting a finite spectral triple. These multitrace matrix models sustain emergent geometry as well as growing dimensions and topology change.

Geometry and Topology of Two-Dimensional Dry Foams: Computer Simulation and Experimental Characterization

Langmuir ◽  
2017 ◽  
Vol 33 (15) ◽  
pp. 3839-3846 ◽  
Author(s):  
Mingming Tong ◽  
Katie Cole ◽  
Pablo R. Brito-Parada ◽  
Stephen Neethling ◽  
Jan J. Cilliers
Keyword(s):  
Computer Simulation ◽  
Two Dimensional ◽  
Experimental Characterization ◽  
And Topology

Structure and Mechanical Properties of Rubberlike Proteins in Animals

1987 ◽  
Vol 60 (3) ◽  
pp. 417-438 ◽  
Author(s):  
John M. Gosline
Keyword(s):  
Amorphous Polymer ◽  
Polymer Networks ◽  
Random Coil ◽  
Future Research ◽  
Random Networks ◽  
Glass Transitions ◽  
Mechanical State ◽  
Protein Molecules ◽  
Polypeptide Chains ◽  
Covalent Crosslinks

Abstract Polymer networks formed from protein molecules that adopt kinetically-free, random-coil conformations are found in many animals, where they play a number of important roles. The 5 rubberlike proteins isolated and studied to date indicate that animal rubbers, like their synthetic counterparts, contain random networks which are usually stabilized by covalent crosslinks. Long-range elasticity in rubberlike proteins is based on changes in the conformational entropy of random-coil molecules. Further, these protein networks show viscoelastic glass transitions similar to all other amorphous polymer networks. Future research on protein sequences should increase our understanding of how polypeptide chains can function as random-coil molecules, and studies into the mechanical state of elastin in arterial tissues may provide important clues about the mechanisms of some forms of human disease.

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