scholarly journals DNA i-motif provides steel-like tough ends to chromosomes

2014 ◽  
Vol 1621 ◽  
pp. 135-141
Author(s):  
Raghvendra P. Singh ◽  
Ralf Blossey ◽  
Fabrizio Cleri
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Mild Steel ◽  
Sampling Methods ◽  
Persistence Length ◽  
Biological Significance ◽  
Umbrella Sampling ◽  
Structural Proteins ◽  
Bending Rigidity

ABSTRACTWe studied the structure and mechanical properties of DNA i-motif nanowires by means of molecular dynamics computer simulations. We built up to 230 nm-long nanowires, based on a repeated TC5 sequence from NMR crystallographic data, fully relaxed and equilibrated in water. The unusual C●C+ stacked structure, formed by four ssDNA strands arranged in an intercalated tetramer, is here fully characterized both statically and dynamically. By applying stretching, compression and bending deformations with the steered molecular dynamics and umbrella sampling methods, we extract the apparent Young’s and bending moduli of the nanowire, as well as estimates for the tensile strength and persistence length. According to our results, i-motif nanowires share similarities with structural proteins, as far as their tensile stiffness, but are closer to nucleic acids and flexible proteins, as far as their bending rigidity is concerned. Curiously enough, their tensile strength makes such DNA fragments tough as mild steel or a nickel alloy. Besides their yet to be clarified biological significance, i-motif nanowires may qualify as interesting candidates for nanotechnology templates, due to such outstanding mechanical properties.

scholarly journals Influence of Defect Number, Distribution Continuity and Orientation on Tensile Strengths of the CNT-Based Networks: A Molecular Dynamics Study

2022 ◽  
Vol 17 (1) ◽  
Author(s):  
Xian Shi ◽  
Xiaoqiao He ◽  
Ligang Sun ◽  
Xuefeng Liu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Carbon Nanotube ◽  
Electronic Devices ◽  
Underlying Mechanism ◽  
Force Transmission ◽  
Tensile Direction ◽  
Defect Number ◽  
Number Distribution

Abstract Networks based on carbon nanotube (CNT) have been widely utilized to fabricate flexible electronic devices, but defects inevitably exist in these structures. In this study, we investigate the influence of the CNT-unit defects on the mechanical properties of a honeycomb CNT-based network, super carbon nanotube (SCNT), through molecular dynamics simulations. Results show that tensile strengths of the defective SCNTs are affected by the defect number, distribution continuity and orientation. Single-defect brings 0 ~ 25% reduction of the tensile strength with the dependency on defect position and the reduction is over 50% when the defect number increases to three. The distribution continuity induces up to 20% differences of tensile strengths for SCNTs with the same defect number. A smaller arranging angle of defects to the tensile direction leads to a higher tensile strength. Defective SCNTs possess various modes of stress concentration with different concentration degrees under the combined effect of defect number, arranging direction and continuity, for which the underlying mechanism can be explained by the effective crack length of the fracture mechanics. Fundamentally, the force transmission mode of the SCNT controls the influence of defects and the cases that breaking more force transmission paths cause larger decreases of tensile strengths. Defects are non-negligible factors of the mechanical properties of CNT-based networks and understanding the influence of defects on CNT-based networks is valuable to achieve the proper design of CNT-based electronic devices with better performances. Graphical Abstract

Effect of Organo-Shell Materials on Compatibility of the Hydrotalcite Flame Retardant in Ethylene Vinyl Acetate

2019 ◽  
Vol 19 (11) ◽  
pp. 7476-7486
Author(s):  
Jinze Du ◽  
Hongyan Zeng ◽  
Enguo Zhou ◽  
Bo Feng ◽  
Chaorong Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Vinyl Acetate ◽  
Md Simulation ◽  
Ethylene Vinyl Acetate ◽  
Flame Retardance ◽  
Strength Tests ◽  
Intrinsic Correlation

The microcapsule nanoparticles were prepared by in-situ copolymerization of hydrotalcites (MAH) with the polymer (MF, PF, PS and PU) monomers, respectively, where the MF-wrapped MAH (MAH@MF) had the best monodispersity. The composites of the microcapsules and EVA were prepared by incorporating the microcapsule nanoparticles into ethylene vinyl acetate (EVA), respectively. To further understand the intrinsic correlation between microcapsule fillers and EVA matrix, molecular dynamics (MD) simulation was introduced to qualitatively analyze the contribution of microcapsule fillers on improving compatibility and mechanical properties of the EVA matrix. The compatibility of microcapsule nanoparticles with EVA matrix were detected in sequence through SEM, DSC and tensile strength tests. And the combustion, thermal behavior and flame retardance were also characterized by TG analyses as well as LOI and UL-94 level. As a result, the MAH@MF filler had the best performances in improving the flame retardancy and mechanical properties among the microcapsule fillers, attributed to high compatibility of the MAH@MF and EVA matrix, which made uniform distribution of the MAH@MF filler due to the reciprocity of triazine functional ring with vinyl acetate linkages.

scholarly journals Effect of Side Surface Orientation on the Mechanical Properties of Silicon Nanowires: A Molecular Dynamics Study

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 102 ◽  
Author(s):  
Xiao Zhuo ◽  
Hyeon Beom
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Silicon Nanowires ◽  
Side Surface ◽  
Surface Orientation ◽  
Dislocation Nucleation ◽  
Cross Sectional ◽  
Tension And Compression

We investigated the mechanical properties of <100>-oriented square cross-sectional silicon nanowires under tension and compression, with a focus on the effect of side surface orientation. Two types of silicon nanowires (i.e., nanowires with four {100} side surfaces and those with four {110} side surfaces) were simulated by molecular dynamics simulations at a temperature of 300 K. The deformation mechanism exhibited no dependence on the side surface orientation, while the tensile strength and compressive strength did. Brittle cleavage was observed under tension, whereas dislocation nucleation was witnessed under compression. Silicon nanowires with {100} side surfaces had a lower tensile strength but higher compressive strength. The effect of side surface orientation became stronger as the nanowire width decreased. The obtained results may provide some insight into the design of silicon-based nano-devices.

scholarly journals Modeling the Mechanical Properties of Functionalized Carbon Nanotubes and Their Composites: Design at the Atomic Level

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Qing-Sheng Yang ◽  
Bing-Qi Li ◽  
Xiao-Qiao He ◽  
Yiu-Wing Mai
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Atomic Level ◽  
Functionalized Carbon Nanotubes ◽  
Buckling Stress ◽  
Compressive Buckling

This investigation focuses on the design of functionalization configuration at the atomic level to determine the influence of atomic structure on the mechanical properties of functionalized carbon nanotubes (F-CNTs) and their composites. Tension and compressive buckling behaviors of different configurations of CNTs functionalized by H atoms are studied by a molecular dynamics (MD) method. It is shown that H-atom functionalization reduces Young’s modulus of CNTs, but Young’s modulus is not sensitive to the functionalization configuration. The configuration does, however, affect the tensile strength and critical buckling stress of CNTs. Further, the stress-strain relations of composites reinforced by nonfunctionalized and various functionalized CNTs are analyzed.

The molecular mechanism of ligand unbinding from the human telomeric G-quadruplex by steered molecular dynamics and umbrella sampling simulations

2015 ◽  
Vol 17 (19) ◽  
pp. 12857-12869 ◽  
Author(s):  
Jia-Kai Zhou ◽  
Dah-Yen Yang ◽  
Sheh-Yi Sheu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Mechanism ◽  
Steered Molecular Dynamics ◽  
Umbrella Sampling ◽  
Energy Profiles ◽  
G Quadruplex ◽  
Free Energy Profiles

The mechanical properties and kinetic pathways of the ligand BMVC unbinding from the G-quadruplex were investigated via the computation of free energy profiles.

Computer Simulation of Nanoparticle Aggregate Fracture

2007 ◽  
Vol 1056 ◽  
Author(s):  
Takumi Hawa ◽  
Brian Henz ◽  
Michael Zachariah
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Computer Simulation ◽  
Tensile Strength ◽  
Direct Relationship ◽  
Brittle Materials ◽  
Ductile Failure ◽  
Strain Behavior ◽  
Nanoparticle Aggregate ◽  
Nanoparticle Aggregates

ABSTRACTNanoparticle aggregates have been found to possess unique mechanical properties. Aggregates of metal nanoparticles can be strained up to 100% before failure, and even typically brittle materials are observed to have a ductile failure mode. In this effort two materials; namely silver and silicon, were chosen to represent ductile and brittle materials, respectively. Aggregates with 2 to 6 particles were simulated using the molecular dynamics (MD) algorithm to determine the stress-strain behavior of the aggregate. Many interesting observations are made including the negligible affect of strain rate on ultimate tensile strength, and the direct relationship between Young's modulus and nanoparticle size.

Molecular dynamics study on the tensile properties of graphene/Cu nanocomposite

2017 ◽  
Vol 06 (03) ◽  
pp. 1750021 ◽  
Author(s):  
Jun Hua ◽  
Zhirong Duan ◽  
Chen Song ◽  
Qinlong Liu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Comparative Analysis ◽  
Strain Rate ◽  
Ultimate Strength ◽  
Strain Rates ◽  
Single Crystal Copper ◽  
Single Slice

In this paper, the mechanical properties, including elastic properties, deformation mechanism, dislocation formation and crack propagation of graphene/Cu (G/Cu) nanocomposite under uniaxial tension are studied by molecular dynamics (MD) method and the strain rate dependence is also investigated. Firstly, through the comparative analysis of tensile results of single crystal copper (Cu), single slice graphene/Cu (SSG/Cu) nanocomposite and double slice graphene/Cu (DSG/Cu) nanocomposite, it is found that the G/Cu nanocomposites have larger initial equivalent elastic modulus and tensile ultimate strength comparing with Cu and the more content of graphene, the greater the tensile strength of composites. Afterwards, by analyzing the tensile results of SSG/Cu nanocomposite under different strain rates, we find that the tensile ultimate strength of SSG/Cu nanocomposite increases with the increasing of strain rate gradually, but the initial equivalent elastic modulus basically remains unchanged.

Effects of Longitudinal Vibration on the Mechanical Properties of Mild Steel Weldments

1993 ◽  
Vol 207 (3) ◽  
pp. 173-177 ◽  
Author(s):  
S P Tewari ◽  
A Shanker
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Mild Steel ◽  
Longitudinal Vibration ◽  
Vibration Experiment

This paper deals with the effect of longitudinal vibration on the mechanical properties of mild steel weldments. The weldments were prepared under different frequencies and amplitudes of vibration. Experiment was carried out in the frequency and amplitude ranges of 0-400 Hz and 0-40 μm respectively. It is found that yield strength, ultimate tensile strength and hardness improves for mild steel specimens welded under vibratory conditions. It is further observed that this improvement in the mechanical properties is appreciable up to 30 μm amplitude.

Structural instability and mechanical properties of MoS2toroidal nanostructures

2015 ◽  
Vol 17 (48) ◽  
pp. 32425-32435 ◽  
Author(s):  
Jianyang Wu ◽  
Gaosheng Nie ◽  
Jun Xu ◽  
Jianying He ◽  
Qingchi Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Young’S Modulus ◽  
Structural Stability ◽  
Md Simulation ◽  
Young's Modulus ◽  
Hierarchical Structures ◽  
Structural Instability ◽  
High Tensile Strength

Classic molecular dynamics (MD) simulation of hypothetical MoS2NT nanorings and their woven hierarchical structures shows a strong dimension-dependent structural stability, and reveals that the hierarchical structures with 4-in-1 weaves exhibit high tensile strength and Young's modulus.

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