scholarly journals Current Understanding of Water Properties inside Carbon Nanotubes

Nanomaterials ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 174
Author(s):  
Aris Chatzichristos ◽  
Jamal Hassan
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Nuclear Magnetic Resonance ◽  
Confined Water ◽  
Scientific Interest ◽  
Open Problems ◽  
Vast Array ◽  
Future Studies ◽  
Nanoconfined Water ◽  
Wide Range

Confined water inside carbon nanotubes (CNTs) has attracted a lot of attention in recent years, amassing as a result a very large number of dedicated studies, both theoretical and experimental. This exceptional scientific interest can be understood in terms of the exotic properties of nanoconfined water, as well as the vast array of possible applications of CNTs in a wide range of fields stretching from geology to medicine and biology. This review presents an overreaching narrative of the properties of water in CNTs, based mostly on results from systematic nuclear magnetic resonance (NMR) and molecular dynamics (MD) studies, which together allow the untangling and explanation of many seemingly contradictory results present in the literature. Further, we identify still-debatable issues and open problems, as well as avenues for future studies, both theoretical and experimental.

scholarly journals Morphoanatomical and histochemical studies of the seed development of Euterpe oleracea (Arecaceae)

Rodriguésia ◽  
2021 ◽  
Vol 72 ◽  
Author(s):  
João Alves Ferreira Pereira ◽  
Ítalo Antônio Cotta Coutinho ◽  
Emanoella Lima Soares ◽  
Arlete Aparecida Soares ◽  
Ana Paula de Souza Caetano ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Seed Development ◽  
Cell Walls ◽  
Palm Tree ◽  
Euterpe Oleracea ◽  
Scientific Interest ◽  
Vast Array ◽  
Future Studies ◽  
Seed Biology ◽  
Fruit Pericarp

Abstract Although the consumption of açaí (Euterpe oleracea) pulp has long been an important component of the diet of the peoples from the Amazon, the açaí palm tree has recently attracted economic and scientific interest because of its vast array of bioactive compounds found in the fruit pericarp. The açaí seeds are the largest byproduct after pulp extraction and have potential for use in ethanol production, but this process is hindered by limited knowledge of seed biology, chemical composition and pattern reserve deposition during seed development. The aim of this work was to describe the morphoanatomical development of the seeds, as well as to identify the main organic compounds stored in the seeds. To achieve this goal, histological and histochemical analyses were performed on developing seeds. Results showed the seed is albuminous, bitegmic and that ingrowths of the seed coat give rise to a ruminate endosperm. Moreover, the nutritive reserves of açaí seeds are found in the endosperm thickened cell walls as reserve polysaccharides. Our findings provide information for future studies dealing with reproductive biology, propagation and the improvement of this profitable crop.

A Molecular Dynamics Simulation Study Towards Understanding the Effects of Diameter and Chirality on Hydrogen Adsorption in Singlewalled Carbon Nanotubes

2003 ◽  
Vol 801 ◽  
Author(s):  
Hansong Cheng ◽  
Alan C. Cooper ◽  
Guido P. Pez ◽  
Milen K. Kostov ◽  
Milton W. Cole ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Hydrogen Adsorption ◽  
Md Simulations ◽  
Substantial Effect ◽  
Dynamics Simulation ◽  
Physical Parameters ◽  
Wide Range ◽  
Field Methodology ◽  
Molecular Forces

ABSTRACTA force field methodology has been developed for the description of carbon-carbon and carbon-molecular hydrogen interactions that is ideally suited to modeling hydrogen adsorption on single-walled carbon nanotubes (SWNT). The method makes use of existing parameters of potential functions developed for sp2 and sp3 hybridized carbon atoms and allows accurate representation of molecular forces on curved carbon surfaces. This approach has been used in molecular dynamics (MD) simulations for hydrogen adsorption in SWNT. The results reveal significant nanotube deformations, consistent with ab initio MD simulations, and the calculated energies of adsorption at room temperature are comparable to the reported experimental heats of adsorption for H2 in SWNT. The efficiency of this new method has permitted the MD simulation of hydrogen adsorption on a wide range of SWNT types, varying such parameters as nanotube diameter and chirality. The results show that these SWNT physical parameters have a substantial effect on the energies of adsorption and hydrogen capacities.

Structure and Dynamics of Water Adsorbed in Carbon Nanotubes: A Joint Neutron-Scattering and Molecular-Dynamics Study

2004 ◽  
Vol 840 ◽  
Author(s):  
Nicolas R. de Souza ◽  
Alexander I. Kolesnikov ◽  
Chun-Keung Loong ◽  
Alexander P. Moravsky ◽  
Raouf O. Loutfy ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Freezing Point ◽  
Mean Square Displacement ◽  
Anomalous Behavior ◽  
Bulk Water ◽  
Confined Water ◽  
Hydrogen Atoms ◽  
Spatial And Temporal Scales ◽  
Wide Range

ABSTRACTThe advent of nanocarbons, from single- and multiple-walled nanotubes to nanohorns, avails model studies of confined molecules on the nanoscale. Water encapsulated inside the quasi-one-dimensional channels of these materials is expected to exhibit anomalous behavior due to the unique geometry of nanotubes and the weak interaction between the water molecules and the carbon atoms. We have employed neutron small-to-wide angle diffraction, quasielastic and inelastic scattering in conjunction with molecular-dynamics simulations to characterize the structures and dynamics of water adsorbed in open-ended single- and double-walled nanotubes over a wide range of spatial and temporal scales. We find that a square-ice sheet wrapped next to the inner nanotube wall and a water chain in the interior are the key structural elements of nanotube-confined water/ice. This configuration results in a hydrogen-bond connectivity that markedly differs from that in bulk water. This significantly softened hydrogen-bond network manifests in strong energy shifts of the observed and simulated inter- and intra-molecular vibrations. The very large mean-square displacement of hydrogen atoms observed experimentally and the strong anharmonicity inferred from simulations explain the fluid-like behavior at temperatures far below the freezing point of normal water.

Water inside carbon nanotubes: structure and dynamics

2016 ◽  
Vol 5 (3) ◽  
Author(s):  
Jamal Hassan ◽  
Georgios Diamantopoulos ◽  
Dirar Homouz ◽  
Georgios Papavassiliou
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Nuclear Magnetic Resonance ◽  
Md Simulations ◽  
Liquid Transport ◽  
Comprehensive Review ◽  
Structure And Dynamics ◽  
Potential Applications ◽  
Nmr Methods ◽  
Theoretical Results

AbstractStudying the properties of water confined in carbon nanotubes (CNTs) have gained a lot of interest in recent years due to the vast potential applications of systems in nanoscale liquid transport as well as biology functions. This article presents a comprehensive review of recent experimental and theoretical results using nuclear magnetic resonance (NMR) and molecular dynamics (MD) simulations. Different NMR methods including

Structures of Water Molecules in Carbon Nanotubes Induced with Electric Fields and its Application for Water-Methanol Separation

2016 ◽  
Vol 842 ◽  
pp. 453-456 ◽  
Author(s):  
Winarto ◽  
Daisuke Takaiwa ◽  
Eiji Yamamoto ◽  
Kenji Yasuoka
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Electric Field ◽  
Electric Fields ◽  
Electrostatic Interaction ◽  
Water Molecules ◽  
Ordered Structures ◽  
Separation Effect ◽  
Wide Range ◽  
Dynamics Simulations

Water confined in carbon nanotubes (CNTs) under the influence of an electric field has interesting properties that are potential for nanofluidic-based applications. With molecular dynamics simulations, this work shows that the electric field induces formation of ordered structures of water molecules in the CNTs. Formation of the ordered structures strengthens the electrostatic interaction between the water molecules. As a result, water strongly prefers to fill CNTs over methanol and it produces a separation effect. Interestingly, the separation effect with the electric field does not decrease for a wide range of CNT diameter.

scholarly journals Observation and analysis of the Coulter effect through carbon nanotube and graphene nanopores

2016 ◽  
Vol 374 (2060) ◽  
pp. 20150357 ◽  
Author(s):  
Kumar Varoon Agrawal ◽  
Lee W. Drahushuk ◽  
Michael S. Strano
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Molecular Transport ◽  
Fluid Phase ◽  
Confined Water ◽  
Stochastic Fluctuations ◽  
Wide Range ◽  
Invaluable Tool ◽  
Pore Properties

Carbon nanotubes (CNTs) and graphene are the rolled and flat analogues of graphitic carbon, respectively, with hexagonal crystalline lattices, and show exceptional molecular transport properties. The empirical study of a single isolated nanopore requires, as evidence, the observation of stochastic, telegraphic noise from a blocking molecule commensurate in size with the pore. This standard is used ubiquitously in patch clamp studies of single, isolated biological ion channels and a wide range of inorganic, synthetic nanopores. In this work, we show that observation and study of stochastic fluctuations for carbon nanopores, both CNTs and graphene-based, enable precision characterization of pore properties that is otherwise unattainable. In the case of voltage clamp measurements of long (0.5–1 mm) CNTs between 0.9 and 2.2 nm in diameter, Coulter blocking of cationic species reveals the complex structuring of the fluid phase for confined water in this diameter range. In the case of graphene, we have pioneered the study and the analysis of stochastic fluctuations in gas transport from a pressurized, graphene-covered micro-well compartment that reveal switching between different values of the membrane permeance attributed to chemical rearrangements of individual graphene pores. This analysis remains the only way to study such single isolated graphene nanopores under these realistic transport conditions of pore rearrangements, in keeping with the thesis of this work. In summary, observation and analysis of Coulter blocking or stochastic fluctuations of permeating flux is an invaluable tool to understand graphene and graphitic nanopores including CNTs.

Constant pH Molecular Dynamics Reveals How Proton Release Drives the Conformational Transition of a Transmembrane Efflux Pump

2017 ◽  
Author(s):  
Jana Shen ◽  
Zhi Yue ◽  
Helen Zgurskaya ◽  
Wei Chen
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Transmembrane Domain ◽  
Conformational Transition ◽  
Conformational Dynamics ◽  
Proton Release ◽  
Intrinsic Resistance ◽  
Constant Ph ◽  
Wide Range ◽  
Constant Ph Molecular Dynamics

AcrB is the inner-membrane transporter of E. coli AcrAB-TolC tripartite efflux complex, which plays a major role in the intrinsic resistance to clinically important antibiotics. AcrB pumps a wide range of toxic substrates by utilizing the proton gradient between periplasm and cytoplasm. Crystal structures of AcrB revealed three distinct conformational states of the transport cycle, substrate access, binding and extrusion, or loose (L), tight (T) and open (O) states. However, the specific residue(s) responsible for proton binding/release and the mechanism of proton-coupled conformational cycling remain controversial. Here we use the newly developed membrane hybrid-solvent continuous constant pH molecular dynamics technique to explore the protonation states and conformational dynamics of the transmembrane domain of AcrB. Simulations show that both Asp407 and Asp408 are deprotonated in the L/T states, while only Asp408 is protonated in the O state. Remarkably, release of a proton from Asp408 in the O state results in large conformational changes, such as the lateral and vertical movement of transmembrane helices as well as the salt-bridge formation between Asp408 and Lys940 and other sidechain rearrangements among essential residues.Consistent with the crystallographic differences between the O and L protomers, simulations offer dynamic details of how proton release drives the O-to-L transition in AcrB and address the controversy regarding the proton/drug stoichiometry. This work offers a significant step towards characterizing the complete cycle of proton-coupled drug transport in AcrB and further validates the membrane hybrid-solvent CpHMD technique for studies of proton-coupled transmembrane proteins which are currently poorly understood. <p><br></p>

scholarly journals A New Method for Dispersing Pristine Carbon Nanotubes Using Regularly Arranged S-Layer Proteins

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1346
Author(s):  
Andreas Breitwieser ◽  
Uwe B. Sleytr ◽  
Dietmar Pum
Keyword(s):  
Carbon Nanotubes ◽  
Covalent Modification ◽  
Silica Layer ◽  
Medical Sciences ◽  
Lysinibacillus Sphaericus ◽  
Wide Range ◽  
Catalytic Sites ◽  
Multi Walled Carbon Nanotubes ◽  
Pristine Mwnts ◽  
Walled Carbon Nanotubes

Homogeneous and stable dispersions of functionalized carbon nanotubes (CNTs) in aqueous solutions are imperative for a wide range of applications, especially in life and medical sciences. Various covalent and non-covalent approaches were published to separate the bundles into individual tubes. In this context, this work demonstrates the non-covalent modification and dispersion of pristine multi-walled carbon nanotubes (MWNTs) using two S-layer proteins, namely, SbpA from Lysinibacillus sphaericus CCM2177 and SbsB from Geobacillus stearothermophilus PV72/p2. Both the S-layer proteins coated the MWNTs completely. Furthermore, it was shown that SbpA can form caps at the ends of MWNTs. Reassembly experiments involving a mixture of both S-layer proteins in the same solution showed that the MWNTs were primarily coated with SbsB, whereas SbpA formed self-assembled layers. The dispersibility of the pristine nanotubes coated with SbpA was determined by zeta potential measurements (−24.4 +/− 0.6 mV, pH = 7). Finally, the SbpA-coated MWNTs were silicified with tetramethoxysilane (TMOS) using a mild biogenic approach. As expected, the thickness of the silica layer could be controlled by the reaction time and was 6.3 +/− 1.25 nm after 5 min and 25.0 +/− 5.9 nm after 15 min. Since S-layer proteins have already demonstrated their capability to bind (bio)molecules in dense packing or to act as catalytic sites in biomineralization processes, the successful coating of pristine MWNTs has great potential in the development of new materials, such as biosensor architectures.

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