Torsional failure of water-filled carbon nanotubes

2015 ◽  
Vol 25 (1) ◽  
pp. 87-97 ◽  
Author(s):  
Hongfei Ye ◽  
Rui Li ◽  
Yonggang Zheng ◽  
Zhongqiang Zhang ◽  
Zhi Zong ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Failure Behavior ◽  
Stability Assessment ◽  
Water Density ◽  
Failure Angle ◽  
Water Filling ◽  
The Stability ◽  
Dynamics Simulations ◽  
Density Of Water ◽  
Torsional Property

The failure behavior of water-filled carbon nanotubes under the torsional moment is investigated by molecular dynamics simulations. The computational results indicate that the shear modulus can be slightly increased but the critical buckling angle can be greatly enhanced by the water filling as compared to the empty carbon nanotubes. The enhancement in the critical buckling angle is almost comparable to that induced by the copper filling. However, the critical failure angle of carbon nanotubes decreases with the increase in the packing density of water, and it is reduced by about 50% when the water density reaches 1.2 g/cm3. Moreover, the researches on the defective water-filled carbon nanotubes reveal that the torsional property of the carbon nanotubes can be influenced by the density and distribution of the Stone–Wales defects. The present findings can provide a theoretical guidance for the stability assessment of nanochannels and the potential application for the drug delivery and release.

EFFECT OF CHIRALITY ON THE STABILITY OF CARBON NANOTUBES: MOLECULAR-DYNAMICS SIMULATIONS

2001 ◽  
Vol 12 (06) ◽  
pp. 865-870 ◽  
Author(s):  
ŞAKIR ERKOÇ ◽  
OSMAN BARIŞ MALCIOĞLU
Keyword(s):  
Heat Treatment ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Potential Energy Function ◽  
Single Wall Carbon Nanotubes ◽  
Many Body ◽  
Chiral Structure ◽  
The Stability ◽  
Dynamics Simulations ◽  
Body Potential

The effect of chirality on the structural stability of single-wall carbon nanotubes have been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that carbon nanotube in chiral structure is more stable under heat treatment relative to zigzag and armchair models. The diameter of the tubes is slightly enlarged under heat treatment.

scholarly journals Molecular Dynamics Study of the Interaction of Carbon Nanotubes with Telomeric DNA Fragment Containing Noncanonical G-Quadruplex and i-Motif Forms

2020 ◽  
Vol 21 (6) ◽  
pp. 1925 ◽  
Author(s):  
Tomasz Panczyk ◽  
Patrycja Wojton ◽  
Pawel Wolski
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Spatial Structure ◽  
Computational Procedure ◽  
Middle Part ◽  
Telomeric Dna ◽  
Neutral Ph ◽  
G Quadruplex ◽  
The Stability ◽  
Dynamics Simulations

This work deals with molecular dynamics simulations of systems composed of telomeric dsDNA fragments, iG, and functionalized carbon nanotubes, fCNT. The iG contains 90 nucleotides in total and in its middle part the noncanonical i-motif and G-quadruplex are formed. Two chiralities of the fCNT were used, i.e., (10,0) and (20,0) and these nanotubes were either on-tip functionalized by guanine containing functional groups or left without functionalization. We proposed a dedicated computational procedure, based on the replica exchange concept, for finding a thermodynamically optimal conformation of iG and fCNT without destroying the very fragile noncanonical parts of the iG. We found that iG forms a V-shape spatial structure with the noncanonical fragments located at the edge and the remaining dsDNA strands forming the arms of V letter. The optimal configuration of iG in reference to fCNT strongly depends on the on-tip functionalization of the fCNT. The carbon nanotube without functionalization moves freely between the dsDNA arms, while the presence of guanine residues leads to immobilization of the fCNT and preferential location of the nanotube tip near the junction between the dsDNA duplex and i-motif and G-quadruplex. We also studied how the presence of fCNT affects the stability of the i-motif at the neutral pH when the cytosine pairs are nonprotonated. We concluded that carbon nanotubes do not improve the stability of the spatial structure of i-motif also when it is a part of a bigger structure like the iG. Such an effect was described in literature in reference to carboxylated nanotubes. Our current results suggest that the stabilization of i-motif is most probably related to easy formation of semiprotonated cytosine pairs at neutral pH due to interaction with carboxylated carbon nanotubes.

Simulations of Pressurized Water Flow through Carbon Nanotubes

2010 ◽  
Vol 1258 ◽  
Author(s):  
Samantha Shaw ◽  
David Faux
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Water Molecules ◽  
Water Density ◽  
Pressurized Water ◽  
Molecular Arrangement ◽  
Flow Through ◽  
Dynamics Simulations ◽  
Maximum Occupancy

AbstractMolecular dynamics simulations of the flow of pressurised water through carbon nanotubes of chirality (9,0), (12,0), (15,0) and (18,0) have been undertaken at 298K with a water density of approximately 1240kg/m3. Results show that the rate of filling is least in the smallest diameter nanotube, but that there is less variation in the time taken to reach maximum occupancy. The water molecules are found to undergo restructuring due to their confinement, with detailed molecular arrangement dependent on CNT diameter. Enhanced rates of flow are shown for the (15,0) nanotube, highlighting the effect of nanotube diameter on confinement and thus on flow.

The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

2020 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Biological Imaging ◽  
Ph Sensing ◽  
Hydrophobic Residue ◽  
Ideal Candidate ◽  
Self Assembling ◽  
Sensing Applications ◽  
Β Sheets ◽  
The Stability ◽  
Dynamics Simulations

<p>pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)<sub>4</sub> systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)<sub>4</sub>-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)<sub>4</sub> containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.</p>

scholarly journals Effect of Size of Multiwalled Carbon Nanotubes Dispersed in Gear Oils for Improvement of Tribological Properties

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Kodanda Rama Rao Chebattina ◽  
V. Srinivas ◽  
N. Mohan Rao
Keyword(s):  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Ball Milling ◽  
Multiwalled Carbon Nanotubes ◽  
Tribological Properties ◽  
Extreme Pressure ◽  
Multiwalled Carbon ◽  
Pristine Mwcnts ◽  
Gear Oil ◽  
The Stability

The aim of the paper is to investigate the effect of size of multiwalled carbon nanotubes (MWCNTs) as additives for dispersion in gear oil to improve the tribological properties. Since long pristine MWCNTs tend to form clusters compromising dispersion stability, they are mildly processed in a ball mill to shorten the length and stabilized with a surfactant before dispersing in lubricant. Investigations are made to assess the effect of ball milling on the size and structure of MWCNTs using electron microscopy and Raman spectroscopy. The long and shortened MWCNTs are dispersed in EP 140 gear oil in 0.5% weight. The stability of the dispersed multiwalled carbon nanotubes is evaluated using light scattering techniques. The antiwear, antifriction, and extreme pressure properties of test oils are evaluated on a four-ball wear tester. It is found that ball milling of MWCNTs has a strong effect on the stability and tribological properties of the lubricant. From Raman spectroscopy, it is found that ball milling time of up to 10 hours did not produce any defects on the surface of MWCNTs. The stability of the lubricant and the antiwear, antifriction, and extreme pressure properties have improved significantly with dispersion shortened MWCNTs. Ball milling for longer periods produces defects on the surface of MWCNTs reducing their advantage as oil additives.

scholarly journals Dispersion of Carbon Nanotubes with “Green” Detergents

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2908
Author(s):  
Kazuo Umemura ◽  
Ryo Hamano ◽  
Hiroaki Komatsu ◽  
Takashi Ikuno ◽  
Eko Siswoyo
Keyword(s):  
Carbon Nanotubes ◽  
Sodium Dodecyl ◽  
Detergent Solution ◽  
Absorbance Spectroscopy ◽  
Fundamental Research ◽  
The Stability ◽  
Single Walled Cnts ◽  
Better Than ◽  
Walled Cnts ◽  
Cnt Suspensions

Solubilization of carbon nanotubes (CNTs) is a fundamental technique for the use of CNTs and their conjugates as nanodevices and nanobiodevices. In this work, we demonstrate the preparation of CNT suspensions with “green” detergents made from coconuts and bamboo as fundamental research in CNT nanotechnology. Single-walled CNTs (SWNTs) with a few carboxylic acid groups (3–5%) and pristine multi-walled CNTs (MWNTs) were mixed in each detergent solution and sonicated with a bath-type sonicator. The prepared suspensions were characterized using absorbance spectroscopy, scanning electron microscopy, and Raman spectroscopy. Among the eight combinations of CNTs and detergents (two types of CNTs and four detergents, including sodium dodecyl sulfate (SDS) as the standard), SWNTs/MWNTs were well dispersed in all combinations except the combination of the MWNTs and the bamboo detergent. The stability of the suspensions prepared with coconut detergents was better than that prepared with SDS. Because the efficiency of the bamboo detergents against the MWNTs differed significantly from that against the SWNTs, the natural detergent might be useful for separating CNTs. Our results revealed that the use of the “green” detergents had the advantage of dispersing CNTs as well as SDS.

scholarly journals sp2 Carbon Stable Radicals

2021 ◽  
Vol 7 (2) ◽  
pp. 31
Author(s):  
Elena F. Sheka
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Black ◽  
Intermolecular Interaction ◽  
Open Shell ◽  
Size And Shape ◽  
Spatially Extended ◽  
Stable Radicals ◽  
The Stability ◽  
Shungite Carbon ◽  
Technological Products

sp2 Nanocarbons such as fullerenes, carbon nanotubes, and graphene molecules are not only open-shell species, but spatially extended, due to which their chemistry is quite specific. Cogently revealed dependence of the final products composition on size and shape of the carbons in use as well as on the chemical prehistory is accumulated in a particular property—the stabilization of the species’ radical efficiency, thus providing the matter of stable radicals. If the feature is highly restricted and rarely available in ordinary chemistry, in the case of sp2 nanocarbons it is just an ordinary event providing, say, tons-in-mass stable radicals when either producing such widely used technological products as carbon black or dealing with deposits of natural sp2 carbons such as anthracite, shungite carbon, and other. Suggested in the paper is the consideration of stable radicals of sp2 nanocarbons from the standpoint of spin-delocalized topochemistry. Characterized in terms of the total and atomically partitioned number of effectively unpaired electrons as well as of the distribution of the latter over carbon atoms and described by selectively determined barriers of different reactions exhibiting topological essence of intermolecular interaction, sp2 nanocarbons reveal a peculiar topokinetics that lays the foundation of the stability of their radical properties.

scholarly journals Stabilizing effect of methylcellulose on the dispersion of multi-walled carbon nanotubes in cementitious composites

2020 ◽  
Vol 9 (1) ◽  
pp. 93-104
Author(s):  
Mingrui Du ◽  
Yuan Gao ◽  
Guansheng Han ◽  
Luan Li ◽  
Hongwen Jing
Keyword(s):  
Carbon Nanotubes ◽  
Pore Solution ◽  
Cementitious Materials ◽  
High Ionic Strength ◽  
Cementitious Composites ◽  
Uniform Distributions ◽  
Stabilizing Effect ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

AbstractMulti-walled carbon nanotubes (MWCNTs) have been added in the plain cementitious materials to manufacture composites with the higher mechanical properties and smart behavior. The uniform distributions of MWCNTs is critical to obtain the desired enhancing effect, which, however, is challenged by the high ionic strength of the cement pore solution. Here, the effects of methylcellulose (MC) on stabilizing the dispersion of MWCNTs in the simulated cement pore solution and the viscosity of MWCNT suspensions werestudied. Further observations on the distributions of MWCNTs in the ternary cementitious composites were conducted. The results showed that MC forms a membranous envelope surrounding MWCNTs, which inhibits the adsorption of cations and maintains the steric repulsion between MWCNTs; thus, the stability of MWCNT dispersion in cement-based composites is improved. MC can also work as a viscosity adjuster that retards the Brownian mobility of MWCNTs, reducing their re-agglomerate within a period. MC with an addition ratio of 0.018 wt.% is suggested to achieve the optimum dispersion stabilizing effect. The findings here provide a way for stabilizing the other dispersed nano-additives in the cementitious composites.

scholarly journals Prediction of Functional Consequences of Missense Mutations in ANO4 Gene

2021 ◽  
Vol 22 (5) ◽  
pp. 2732
Author(s):  
Nadine Reichhart ◽  
Vladimir M. Milenkovic ◽  
Christian H. Wetzel ◽  
Olaf Strauß
Keyword(s):  
Transmembrane Protein ◽  
Functional Characterization ◽  
Missense Mutations ◽  
Mutant Proteins ◽  
Functional Consequences ◽  
New Perspective ◽  
The Stability ◽  
Dynamics Simulations ◽  
And Function

The anoctamin (TMEM16) family of transmembrane protein consists of ten members in vertebrates, which act as Ca2+-dependent ion channels and/or Ca2+-dependent scramblases. ANO4 which is primarily expressed in the CNS and certain endocrine glands, has been associated with various neuronal disorders. Therefore, we focused our study on prioritizing missense mutations that are assumed to alter the structure and stability of ANO4 protein. We employed a wide array of evolution and structure based in silico prediction methods to identify potentially deleterious missense mutations in the ANO4 gene. Identified pathogenic mutations were then mapped to the modeled human ANO4 structure and the effects of missense mutations were studied on the atomic level using molecular dynamics simulations. Our data show that the G80A and A500T mutations significantly alter the stability of the mutant proteins, thus providing new perspective on the role of missense mutations in ANO4 gene. Results obtained in this study may help to identify disease associated mutations which affect ANO4 protein structure and function and might facilitate future functional characterization of ANO4.

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