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Yolk-shell SnO2 mesoporous double-layer nanotubes were synthesized in one-step by single nozzle electrospinning. Compared with the traditional electrospinning using polyvinylpyrrolidone (PVP) as the precursor polymer to obtain the single nanotube material, two PVPs (PVPK88-96 and PVPK23-27) with different molecular weights in solution coupled with Sn2+ easily form the core-shell structure nanofiber through phase separation. The yolk-shell double-layer SnO2 nanotubes were obtained after calcination at 600 °C for 2 h. The yolk-shell SnO2 mesoporous double-layer nanotube is a promising sensing material toward 3-hydroxy-2-butanone as it shows high sensitivity, cycling stability, and selectivity. Moreover, the response and recovery times of the yolk-shell SnO2 mesoporous double-layer nanotubes toward 1 ppm 3-hydroxy-2-butanone were 122 s and 117 s. [ABSTRACT FROM AUTHOR]

The modified strain gradient theory (MSGT) with flexoelectric and micro-inertia effects is developed to study the free vibration of tube made of elastic centrosymmetric materials. Within this theory, the internal energy density is the function of the strain tensor, deviatoric part of stretch gradient and rotation gradient tensors, dilatation gradient, polarization vector, and electric quadrupoles. The linear coupled governing equations and boundary conditions are derived from the Hamilton variation principle. The torsional vibration problem is analytically solved for non-piezoelectric nanotube with fixed edges. The effect of the nanotube geometry, flexoelectric coefficient, micro-inertia, and micro-stiffness parameters on the natural frequency is studied. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDCs) are among the most exciting materials in nano-size particles. In this study, MX2 (M = Mo and W; X = S, Se, and Te) nanotubes and monolayers were evaluated to show the structural, mechanical, and electronic properties. The results showed that the stability of MX2 monolayers changes similarly to nanotubes with the sequence of MS2 > MSe2 > MTe2 (M = Mo and W). Besides, MX2 nanotubes and monolayers are semiconductors, and the band gap energy increases with a similar sequence with stability properties. The structural stability and band gap energy of WX2 structures are more than MoX2 structures. Young's modulus of nanotubes was studied with density functional theory (DFT) and molecular dynamics (MD) simulations with Stillinger-Weber (SW) potential methods. The results are similar to the formation and band gap energy showing that Young's modulus of the MX2 structures is in order of MS2 > MSe2 > MTe2 (M = Mo and W) and WX2 > MoX2 (X = S, Se or Te). Structural defects in monolayers, which were M-vacancy (VM), X2-vacancy (VX2), M-X2-vacancy (VM-X2), and M-X4-vacancy (VM-X4), were studied and it showed that the mechanical properties could be decreased. However, the defects do not affect electronic properties. [ABSTRACT FROM AUTHOR]

AbstractConventional systemic cancer therapy often causes numerous adverse events. However, discovering overexpressed folate receptors in solid tumours has paved the way for targeted chemotherapy. Folic acid (FA), a ligand for these receptors, is frequently combined with chemotherapeutic drugs to improve their effectiveness. Carbon nanotubes have emerged as a versatile and promising method for delivering these folate-conjugated nano-systems, ensuring targeted delivery of therapeutic agents to cancerous cells. When FA-conjugated nanotubes dissociate, they release the drug-loaded nanotubes inside the malignant cells, reducing off-target effects. These nanotubes can also be used for combination therapies, producing synergistic effects. This review aims to comprehensively gather and critically evaluate the latest methods for delivering therapeutics using FA-conjugated nanovehicles. Additionally, it seeks to enhance our comprehension of the pertinent chemistry and biochemical pathways involved in this approach. [ABSTRACT FROM AUTHOR]

In the current paper, hygro-thermo-magnetically induced vibrations of small-scale viscoelastic tubes containing flow with a spin motion under gravity and tangential loads are analyzed by including surface effects. The dynamic equations are derived in the framework of the modified nonlocal elasticity theory (NET) and Rayleigh beam model. The Galerkin method and Laplace transformation are implemented to solve model equations. Vibration frequencies, stability boundaries, and Campbell diagrams of the system are acquired. Impacts of influential parameters such as scale rotary inertia factor, scale parameter, viscoelastic materials, gravity and tangential loads, flow and spin velocities, geometrical properties, and environmental conditions on the stability of the structure are examined. Also, the obtained results are compared for the Rayleigh and Euler-Bernoulli (EB) beam models. The golden results of this work are that by fine-adjusting the scale parameter and magnetic intensity in the system, destructive effects of hygro-thermal loads can be dampened. Besides, the increment of the rotary inertia factor and nanotube thickness induces destabilizing effect on the system. [ABSTRACT FROM AUTHOR]

In this research, the nonlinear vibration behavior of axially functionally graded (AFG) nano-scale truncated conical tubes (with non-uniform cross-section), including the porosity, is presented for the first time based on the Euler-Bernoulli beam theory and the von-Kármán's nonlinear strain-displacement and nonlinear nonlocal boundary conditions. The effect of being at the tapered nanosize model is supposedly based on the nonlocal strain gradient theory using the Hamilton principle to extract the equation of motions and nonlinear time-dependent nonlocal boundary conditions. The material properties and thickness of nano-tube are varying along the length of tubes. The generalized differential quadrature method (GDQM) is utilized with the iteration method to solve the complicated nonlinear equations. The numerical results in tabular and graphical styles present for various nonlinear amplitudes, the AFG power indexes, the rate of the cross-section change, the porosity parameter, and the nonlocal gradient strain parameter for both simply supported, fully clamped, and simply supported-clamped boundary conditions in detail. [ABSTRACT FROM AUTHOR]

This paper deals with the free and forced, linear and nonlinear vibration of functionally graded (along with thickness) nanotube, considering the non-uniform cross-section that made a two-dimensional functionally graded (2D-FG) structure. The bi-dimensional nanostructure-dependent governing equation is modeled based on the classic beam theory (Euler-Bernoulli), and they are derived by Hamilton's principle based on nonlocal gradient strain theory considering the von-Kármán nonlinear strain and the external harmonic load. To solve the general equations and calculate the results, the generalized differential quadrature method (GDQM) was used coupled with the numerical iteration method for the nonlinear response. The results are discussed for the different simply-supported and clamped boundary conditions. The 2D-FG nanotube's behavior is analyzed for different nonlinear amplitudes, nonlocal strain gradient parameters and nonlocal parameters, different rates of cross-sections, and different material distributions. [ABSTRACT FROM AUTHOR]

Nanotubes could be fabricated in different shapes for various applications, as they have the possibility of changing curvature. Vibration and stability of a curved nanotube conveying fluid and nanoparticle are investigated considering surface and non-local effects. The surface effects are considered in the nanotube inner and outer layers. The obtained equation is discretized using the Galerkin method. The main parameter effects on the stability and the first two modes are illustrated, including the total opening angle, the nanoparticle mass-ratio, the non-local parameter, the surface-effects parameter, and the nanoparticle position. They show significant effects on the dynamic behavior of the nanostructure. [ABSTRACT FROM AUTHOR]

To use Al composites in structural applications, we need to improve strength and ductility at the same time. In this article, we explore three main concepts to solve this problem: improving the dispersion uniformity of CNTs in Al powder without damaging its structure by solution coating technique, fabricating a hybrid composite by reinforcing Al with nano-TiC-CNT, comparing the properties of nano-TiC-CNT and micron-TiC-CNT hybrid composites. Microstructure observation by SEM, TEM, and XRD revealed well-dispersed and preserved CNTs without the formation of a second phase. The Al-0.5CNT composite showed good tensile strength and elongation at break of 278 MPa and 14%, respectively. Further improvements in tensile strength and ductility of 285 MPa and 23%, respectively, were measured after the addition of 2.5 wt%; (1.4 vol%) TiC nanoparticles to Al-0.5CNT composite. However, the introduction of 2.5 wt-% TiC macroparticles only improved the tensile strength by 48% but elongation at break was up to 32%. The improved strength and ductility are attributed to the introduction of geometrical necessary dislocation and Orowan looping of dislocations leading to back stress strengthening. The new Al composite is expected to find application in automotive and aerospace component manufacture and thermal management. [ABSTRACT FROM AUTHOR]

Eudragit L100-55-halloysite nanotubes (EL100-55, HNTs) nanocomposite microcapsules were introduced to release nattokinase (NK) and avoid the limitations of oral and systemic administration of NK while increasing the entrapment efficiency and stability of NK. The drug loading capacity, stability, and shapes of the NK microcapsules (NK@HNTs-EL) were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The maximum loading rate of NK was 82.63%, and the encapsulation efficiency of NK was 31.6%. The formulation conditions did not adversely affect the NK tertiary structure. The maximum in vitro drug release in the simulated small intestine buffer was 93.3%, and the NK@HNTs-EL exhibited pH-dependent drug release. The drug release data were analyzed with different kinetic models, which showed that the NK@HNTs-EL drug-release mechanism involved erosion and osmotic pressure on the EL100-55. After 90 days of storage, the NK@HNTs-EL maintained an enzymatic activity greater than 95%. Hemolysis analyses indicated that NK@HNTs-EL was not cytotoxic at concentrations below 500 FU/mL. These findings indicate that NK@HNTs-EL is a promising oral thrombolytic agent. [ABSTRACT FROM AUTHOR]

Present study deals with the nonlinear analysis of thermally induced deflection and snap-through buckling in functionally graded porous (FGP) curved nanotubes. It is assumed that the curved nanotube is rested on a two-parameter nonlinear elastic foundation. The curved nanotube is subjected to uniformly distributed transverse pressure loading and also uniform temperature rise. Distribution of thermomechanical properties in the thickness of curved nanotubes is radially graded according to a power law function. The even type of porosity distribution patterns is included into the formulation and all properties are considered as temperature dependent. The nonlocal strain gradient and uncoupled thermoelasticity theories are provided to analyze the geometrically nonlinear behaviors of curved nanotubes. The equilibrium equations are obtained based on the high-order shear deformation theory. To capture the large deformations, the von Kármán type of nonlinear kinematic assumptions is included. Two types of immovable boundary conditions are considered which are simply-supported and clamped-clamped. The equilibrium equations are reformulated and transferred into the dimensionless presentation. The closed-form expressions are provided to trace the thermal/mechanical load-deflection paths of curved nanotubes using the two-step perturbation technique. Numerical results of this study are compared with the available data in the literature for the macro-scale curved tubes. After that novel parametric results are provided to discuss the effects of nonlocal and length scale parameters, boundary conditions, porosity coefficient, foundation stiffness, power law exponent, and geometrical parameters. [ABSTRACT FROM AUTHOR]

For realizing precise control of nanoscaled or micrometer-scaled peristaltic pumping, it is necessary to reveal its detailed behaviors by in situ electron microscopy observations. This study provides in situ observation of micrometer-scaled peristaltic pumping. A carbon microtube with a Ga filler was manipulated using two microprobes in a scanning electron microscope. When the tube was pinched by the probes, the filler was pushed toward the end of the tube. Upon further pinching, the filler was divided into two portions with a gap at the pinching position. Our observation suggests that when using carbon nanotubes, a material known for its excellent mechanical durability, manipulators should be operated not to break the nanotubes. [ABSTRACT FROM AUTHOR]

Recent research has mostly focused on replacing traditional lubricants with nanoparticle-based fluids to increase machining performance. The current work compares three distinct environmental conditions in turning of A286 alloy: oil machining (OM), nano Low Quantity Lubrication (nLQL), and LN2 (liquid nitrogen). Cutting speed (Vs), environment, and feed rate (f) were used as control parameters, with responses assessed in terms of flank wear (Vb), crater wear, surface roughness (Ra), machining temperature (Mt), and chip morphology. The L27 array was chosen for the testing runs. The experimental findings demonstrated that LN2 cooling significantly lowered Ra by 54% and 24%, Vb by 62% and 53%, and Mt by 45% and 73% when compared to the OM and nLQL settings. Under cryogenic circumstances, surface integrity was also enhanced. COPRAS, a multi-response optimization approach, was used to determine the best trials for picking the best outcomes. [ABSTRACT FROM AUTHOR]

The control of the localization of halloysite nanotubes (HNT) in a linear low-density polyethylene/ethylene-vinyl acetate copolymer (LLDPE/EVA, 70/30) blend was studied through three approaches: i) Functionalization of the filler, ii) Addition of a compatibilizer and iii) Modification of the processing sequence. First, the HNT surface modification was carried out with three different organosilanes (3-aminopropyltriethoxysilane (APTES), dodecyltricholosilane (DTCS) and triacontyltrichlorosilane (C30)). Grafting amounts about 0.10 mmol/g were reached whatever the nature of the organosilane. Then, the unmodified and modified HNT were mixed with a LLDPE/EVA (70/30) polymer blend using a microextruder and the localization of the fillers were scrutinized by scanning electron microscopy (SEM) analysis. It was observed that both the neat HNT and modified HNT were mostly localized in the EVA phase. These observations were also discussed according to the wettability coefficient determined for neat HNT and modified HNT thanks to contact angle measurements. The addition of PE-g-MA as a compatibilizer to the blend containing the HNT-APTES allowed to localize the HNT in the LLDPE phase. Finally, the influence of the mixing sequence of the different components was evaluated by using a twin-screw extruder, and it was successfully used to localize the modified HNT into the LLDPE phase. [ABSTRACT FROM AUTHOR]

The superior physical and mechanical performances of halloysite nanotubes (HNTs) make them ideal fillers for rubber reinforcement. However, due to the abundant hydroxyl groups on their surface, they are highly polar and have poor compatibility with polymers, making it difficult for them to disperse uniformly in polymers, thus limiting their application in rubber composites to a certain extent. In this paper, noncovalently modified HNTs filled with a natural rubber/chloroprene rubber/chloro-isobutylene-isoprene rubber (NR/CR/CIIR) blend system, using polydopamine(PDA) as a surface modifier, was investigated. and a green and high-performance PDA/HNTs/NR/CR/CIIR composite was prepared by mechanical blending. Transmission electron microscopy (TEM) showed that the original HNTs had a hollow, multi-walled nanotube structure, and the outer surface of the PDA-modified halloysite nanotubes(PDA/HNTs)showed an obvious cladding layer. X-ray diffraction indicated that the modification experiments did not damage the halloysite crystal structure; the modifier only interacted on the outer surface of the HNTs. Zeta potential and thermogravimetric analysis (TGA) further indicated the presence of interfacial interactions between PDA and HNTs, suggesting that PDA was successfully grafted to the surface of HNTs. In addition, the effects of PDA/HNTs on the mechanical properties, vulcanization properties and Rubber Process Analyzer (RPA analysis) of the NR/CR/CIIR blend were also investigated. The dispersion of HNTs in the NR/CR/CIIR blend was enhanced by the adsorption of PDA on the HNTs surface by non-covalent bonds, and the comprehensive properties of the composites were improved. [ABSTRACT FROM AUTHOR]

In this manuscript, the potential utility of 6CF macrocyclic oligofuran is theoretically investigated to create novel nanotubes. The energetic, electronic, structural and topological properties of π-stacked systems are examined at B3LYP/6-31 + G(d), wB97XD/6-31 + G(d) and M06-2X/6-31 + G(d) levels of theory. The findings indicate that the self-assembly of 6CF macrocyclic oligofurans can be considered to create organic nanotubes through π–π stacking. The strength and nature of π-π interactions are examined using the atoms in molecules (AIM) approach. Meaningful relationships are obtained between stability, electronic properties and the number of stacked π-conjugated macrocyclic oligofurans. The stability and polarisability of π-stacked systems are amplified by increasing number of macrocycles. Reverse behaviours are found for the values of band gap, electronic chemical potential and first ionisation energy. [ABSTRACT FROM AUTHOR]

In this study, Cht/PS-CA/HNT biocomposite adsorbent was synthesized using halloysite nanotube as nanomaterial, chitosan which is a biodegradable and biocompatible biopolymer, pistachio shell as biomass source, citric acid as biomass modifier. The removal of methylene blue dyestuff on the synthesized new Cht/PS-CA/HNT from the aqueous medium by adsorption method was investigated. Experimental parameters such as dye concentration, contact time, amount of adsorbent, solution pH and temperature, which affect the adsorption process, were investigated. The adsorption experimental data were analyzed with the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms, which are widely used in aqueous solutions, and it was decided that Langmuir is the most suitable isotherm. The maximum adsorption capacity of the monolayer was calculated to be 111.14 mg/g. Optimum contact time and adsorbent dose were determined as 90 min and 1 g/L. Adsorption experimental data were applied for Pseudo-first-order and Pseudo-second-order kinetic models and it was decided that the most suitable kinetic model was pseudo-second-order. Thermodynamic evaluation of adsorption showed that adsorption is endothermic and adsorption is spontaneous. In the present study, it was determined that chitosan beads prepared using citric acid modified pistachio shells and HNT have strong adsorption properties for dyestuff removal, which is one of the important causes of environmental pollution. The novelty of this work is based on the development of a new composite adsorbent that can be synthesized in a simple and fast method and does not require expensive reagents or complex equipment. Another innovation is that MB dyestuff, which has a highly harmful effect, can be easily removed from polluted water by using simple biowaste-based adsorbents by adopting appropriate procedures. [ABSTRACT FROM AUTHOR]

It is well known that lubricating oils reduce the friction coefficient between two surfaces in contact. Since petroleum lubricants are toxic and have a low biodegradability, they are typically not appropriate for the environment. As a result, as public worries about a pollution-free environment grow, so does the demand for lubricants that are acceptable to the environment. The primary rationale for utilizing vegetable oils in forthcoming bio-lubricant formulations is their high lubricating performance, low toxicity, sustainable, and biodegradability. Plant oils hold great potential as a foundational fluid for bio-lubricants, since their synthetic and vegetable oil-based esters provide the most environmentally friendly option for creating lubricants. In this study, Jatropha and Jojoba raw oil were chemically modified via epoxidation followed by transesterification to produce bio-lubricants. Thus, the aim of this work is to develop a bio-lubricant from jatropha and jojoba methyl ester, further adding nanoparticles multiwalled nanotubes and titanium dioxide for improvement of tribological properties. The chemical modification of the jatropha and jojoba oil results in a decrease in iodine value, resulting in the breaking of carbon bonds. Viscosity tests were performed using the Anton Par MCR 92 Rheometer, with temperature ranging from 30°C to 80°C. Thermal stability measurements of bio-lubricants were performed using PerkinElmer’s Thermogravimetric analyzer-4000 instrument and thermal degradation temperature for Epoxidized Jatropha-sulfuric acid, Epoxidized Jatropha-hydrochloric acid, Epoxidized Jojoba-sulfuric acid and Epoxidized Jojoba-Hydrochloric acid samples are 238°C, 224°C, 230°C, and 244°C, respectively. The 94.68% and 79.85% reduction in wear was obtained for Epoxidized Jojoba with hydrochloric acid, titanium dioxide and epoxidized Jatropha with sulfuric acid, multiwalled carbon nanotubes in comparison with their epoxidized samples. The coefficient of friction of Epoxidized Jatropha with sulfuric acid, multiwalled carbon nanotubes and Epoxidized Jojoba with Hydrochloric acid, Titanium dioxide sample was found to be 0.061 and 0.059, respectively [ABSTRACT FROM AUTHOR]

Circumscribing benzenoid polycyclic aromatic hydrocarbons was first introduced in 1982 under the topic of a periodic table for benzenoid hydrocarbons and isomer enumeration. This circumscribing process was rendered on benzene to successively generate coronene, circumcoronene, dicircumcornene, and so on as the first constant-isomer series. Subsequently, numerous benzenoid constant-isomer series were uncovered because of the coupling of the benzenoid periodic table (Table PAH6) and circumscribing. Circumscribing even carbon monocyclic polyenes produced [n]cyclacenes (n = number of hexagonal rings) which are monotier nanotubes. Starting with [n]cyclacenes and successive circumscribing generates (n,0) Zigzag nanotubes of increasing length. Successive circumscribing cycloparaphenylenes leads to (n,n) Armchair nanotubes of increasing length. Successive supercircumscribing cycloparaphenylenes leads to total-resonant-sextet Armchair nanotubes of maximum stability. Circumscribing polycyclic conjugated systems was subsequently introduced for other ring sizes. Circumscribing polycyclic hydrocarbons with a combination of pentagonal and hexagonal rings leads to fullerenes when 12 pentagonal ring is reached. Generation of altans is a specialised type of circumscribing in which the encircling annulene is attached via its alternate degree-2 vertices to the degree-2 vertices of the core structure. We show that monocapped nanotubes are circumscribed altans. [ABSTRACT FROM AUTHOR]

This work investigates the fundamental photocatalytic properties of nitrogen-doped single-walled silicon carbide nanotubes (N-doped SWSiCNTs) for hydrogen evolution for the first time. Investigations of the structural, mechanical, electronic, and optical properties of the studied systems were carried out using popular density functional theory implemented in quantum ESPRESSO and Yambo codes. Analysis of the structural properties revealed high mechanical stability with the 3.6% and 7.4% N-doped SWSiCNT. The calculated band gap of the N-doped SWSiCNT with 3.6% demonstrated a value of 2.56 eV which is within the photocatalytic range of 2.3 eV−2.8 eV. The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) potentials of the 3.6% N-doped SWSiCNT also showed good agreement with previous theoretical data. The studied material showed the best photocatalytic performance in both parallel and perpendicular directions by absorbing photons in the visible region. Therefore, the observed structural, mechanical, electronic and optical behaviors demonstrated by the 3.6% N-doped SWSiCNT exposed it as a better photocatalyst for hydrogen production under visible light. This work reports fundamental photo-performance properties of a new system, i.e. nitrogen-doped single-walled silicon carbide nanotubes (N-doped SWSiCNTs) as photocatalysts for the overall water splitting for the first time. The observed structural, mechanical, electronic and optical behaviors demonstrated by the N-doped SWSiCNT exposed it as a better photocatalyst for hydrogen production under visible light, indicating it to be a better candidate for photocatalytic applications such as water splitting, biodegradation, and wastewater purification. 3.6% N conc. has been found to be the suitable photocatalyst for water splitting. [ABSTRACT FROM AUTHOR]

A promising paradigm for drug administration that has garnered increasing attention in recent years is the direct transfer (DT) of nanoparticles for transcellular drug delivery. DT requires direct cell-cell contact and facilitates unidirectional and bidirectional matter exchange between neighboring cells. Consequently, DT enables fast and deep penetration of drugs into the targeted tissues. This comprehensive review discusses the direct transfer concept, which can be delineated into the following three distinct modalities: membrane contact-direct transfer, gap junction-mediated direct transfer (GJ-DT), and tunneling nanotubes-mediated direct transfer (TNTs-DT). Further, the intercellular structures for each modality of direct transfer and their respective merits and demerits are summarized. The review also discusses the recent progress on the drugs or drug delivery systems that could activate DT. [ABSTRACT FROM AUTHOR]

Poly (ether-ether-ketone) (PEEK) is one of the most promising engineering plastics in aerospace engineering because of their reliable mechanical properties under various conditions. However, next-generation engineering plastics also call for more comprehensive outputs, such as higher thermal conductivity and antiwear performances. Boron Nitride Nanotubes (BNNT) have been proven to have outstanding physical properties as additives to the resin of the composites. In this article, the influence of BNNT additives on the PEEK resin is studied to provide a more insightful understanding of the development of BNNT-reinforced engineering plastics in the future. It has been found that the interfacial shear strength (IFSS) between BNNT and PEEK is 151% higher than carbon nanotube reinforcements., and amino groups (–NH2) modified BNNT can further improve the IFSS value by 14%. This mechanical improvement is further evaluated, and the molecular mechanisms are explained with an atomistic resolution. [ABSTRACT FROM AUTHOR]

The present in vitro study evaluated the effect of titanium nanotubes (nTiO2) application on high translucent zirconia (Copra Supreme, Whitepeaks) on shear bond strength values with different self-adhesive resin cements (Panavia V5, G-Cem One, and Variolink Esthetic DC). One hundred and forty-eight specimens were prepared and randomly divided into four groups (n = 37) according to surface treatment groups (air-abraded sintered zirconia, air-abraded pre-sintered zirconia, application of nTiO2 on zirconia, and application of nTiO2 on air-abraded zirconia). nTiO2 were produced by alkaline hydrothermal synthesis, mixed with isopropyl alcohol (50 wt%), and applied on pre-sintered zirconia. The surface roughness (Ra) was examined. Sintered surfaces were characterized by field emission scanning electron microscope (Fe-SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis. Surface treatment groups were randomly divided into three subgroups according to self-adhesive resin cement (n = 12). Luting procedures were performed and specimens were stored in water at 21 °C for 6 months before the shear bond strength test. Data were analyzed by one-way ANOVA and two-way ANOVA. Fe-Sem images and EDS confirmed the incorporation of nTiO2 on zirconia. Surface treatment methods affected the Ra of zirconia (p <.001). Surface treatment method (p =.013) and self-adhesive resin cement (p <.001) affected shear bond strength values. The lowest shear bond strength values were achieved in applied nTiO2 on high translucent zirconia specimens (p <.05). The lowest shear bond strength values were determined in the Variolink Esthetic DC group (p <.05). Application of nTiO2 on air-abraded high translucent zirconia surface had no significant effect on the shear bond strength (p >.05). [ABSTRACT FROM AUTHOR]

As the performance of natural rubber (NR) and halloysite nanotube (HNT) composites is uncertain due to low compatibility between the materials, malleated natural rubber (MNR) is then used as a compatibilizer to encourage filler–rubber compatibility. However, the properties of these composites remain unsatisfactory, and the treatment of HNT requires further improvement. Therefore, this study introduced acid treatment and silane coupling agents to increase the interactions between NR and HNT. Besides, this study also introduced the methods of compounding the rubber composites, either with single-stage or two-stage treatments. The application of a two-stage treatment to acid-treated HNT has given tensile strength a 26.5% improvement. Two-stage treatment enabled better silanization, while acid-treated HNT provided effective silanols for such interactions. The use of silane with acid-treated HNT was found to enhance the tensile strength, modulus, and tear strength of the composites, which was clearly due to better filler–rubber interactions. The Payne effect, which decreased up to 64.03% after applying a two-stage treatment, served as further confirmation of better filler–rrubber interactions. This conclusively proved that modifying both the rubber matrix and HNT enhances the performance of NR/HNT composites. [ABSTRACT FROM AUTHOR]

In a molecular graph, a Kekulé structure and perfect matching resembles the same. Thus, the number of Kekulé structure(chemically) is equal to the number of perfect matching (mathematically) required to cover the edge set or covalent bonds of a molecular graph entirely. The number of possible Kekulé structures in a molecule (benzenoids) is used to describe the extent of its aromatic property and plays an significant role in the analysis of resonance energy and stability of certain chemical compounds. In this article, the minimum number of Kekulé structures (K) that covers all the edges of a class of peri-condensed benzenoid graphs possessing three rows of hexagon of various length and P r [ m , n ] -polyacenic nanotubes were discussed and summarized. [ABSTRACT FROM AUTHOR]

A composite of bacterial cellulose and titanate nanotubes (BC/TNT) was prepared for use as a stretchable motion sensor in smart and wearable electronics. The composite was characterized using various techniques such as UV-VIS-NIR spectroscopy, SEM, XRD, IR spectroscopy, and thermogravimetric analysis. It was found that the dielectric constant of BC/TNT was up to 2.6 times that of BC with similar loss tangent, indicating improved charge storage. The composite was also constructed into a Kirigami pattern for improved stretchability. With a tensile strain of 0.4%, the change in resistance relative to the original resistance (ΔR/R0) was found to be 5.7% and 6.9% for BC and BC/TNT, respectively, demonstrating improved sensing performance. [ABSTRACT FROM AUTHOR]

In this experimental work, homogeneous nanotube layers were successfully formed by anodization on titanium wires with diameters lower than 200 µm employing an aqueous anodizing solution composed of carboxymethylcellulose and sodium fluoride. Homogeneous nanotube layers were formed only when the titanium wires were electropolished. After heat treatment at 350 and 600°C, the nanotubes were transformed from amorphous phase into anatase phase or a mix between anatase and rutile phases. After both heat treatments, the nanotube coatings remained uniform; namely, no apparent cracks, critical defects, or coating delamination were seen. To the best of our knowledge, a homogeneous nanotube coating composed of anatase or a mix between anatase and rutile phases on titanium wires with diameters lower than 200 µm has not been reported. These coatings may be potentially useful in a variety of fields, including biomedicine, sensing, and catalysis. [ABSTRACT FROM AUTHOR]

The impact of modulated temperature on the synthesizes zirconium doped cobalt selenide material has been investigated in this study. The morphology, structure, elemental composition, behavior in light, and electrical properties of the synthesized materials were investigated using scanner electron microscopy (SEM), X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX), ultraviolet-visible (UV-vis) spectrophotometer, and a four-point probe device. Due to the agglomeration of the film, the surface morphology exhibits white clove-like clusters and a sizable surface area. The clusters are denser and smaller as the modulated temperature rises, with the exception of the material produced at 205oC, which exhibits large nanoparticles and a small amount of nanotube. The diffraction planes 111, 200, 202, 300, and 311 agree with the spectrum's reported prominent crystalline peak at 2 theta degree angle, which appears at 11.1666, 14.7349, 21.8029, 26.3319, and 30.8953. Bandgaps of 1.39, 1.52, 1.25, and 1.50 eV were found for cobalt selenide-doped zirconium and 1.66 eV for cobalt selenide, respectively. [ABSTRACT FROM AUTHOR]

This paper aims to study imperfect nanotubes' buckling behavior made of functionally graded materials with porosity and non-uniform cross-section. The nonlocal strain gradient theory is used to define the size effect in nano-scale, and also new higher order tube model and first-order shear deformation theory are utilized to develop the nanotube's formulation. The results are obtained using the generalized differential quadrature method and are compared to the Timoshenko theory with very satisfying convergence. The boundary conditions are considered as clamped, clamped-simply supported, and also simply supported. The results illustrate the effects of the FG power index, porosity, rates of cross-section change, nonlocal, and strain gradient parameters on the buckling behavior of the FG tapered porous nanotube. [ABSTRACT FROM AUTHOR]

TiO2 nanotubes were synthesized by hydrothermal reaction using commercially available TiO2 powder at 150 °C for 24 h. The transmission electron microscopy, X-ray diffraction, nitrogen adsorption-desorption isotherms and Fourier Transform-Infrared spectroscopy were used to characterize the nanotubes. Anatase phase was not transformed into rutile phase in the range of calcination temperature studied. Increase in calcination temperature result in enhancement of crystallinity and reduction in BET surface area. Photocatalytic removal of Reactive Red 239 (RR239) was investigated using prepared TiO2 nanotubes. Effects of pH, TiO2 nanotube dosage, initial RR239 concentration and calcination temperature were studied. 99%, 97% and 55% of removal efficiency values were attained at pH = 3, 5 and 7, respectively within 60 min or reaction time. With an increase in dosage of TiO2 nanotube in the range of 0.25–0.75 g dm−3, removal rate increased by a steeper slope. Complete removal of RR239 was observed at 20 mg dm−3 RR239 concentrations within 30 min but longer time was required for complete removal at higher concentrations. Langmuir-Hinshelwood kinetic expression was proposed based on nonlinear regression analysis. The removal efficiency of nanotubes calcined at 300 − 450 °C significantly increased but further increase in calcination temperature caused to decrease the efficiency.100% and 85% removal efficiency values were observed using actual solar light within 120 min of reaction time in July and January, respectively. Experiments conducted with scavengers showed that holes and adsorbed hydroxyl radicals were the major species involved in removal of RR239. A pathway for degradation of RR239 was suggested according to detected intermediate compounds. [ABSTRACT FROM AUTHOR]

An ultra-low power 8-Transistor Modified Gate Diffusion Input (MGDI) Carbon Nano Tube Field Effect Transistor (CNTFET) Full Adder (FA) has been presented in this paper. The proposed 8-T MGDI CNTFET Full Adder outperforms other adders in terms of Power Consumption, Propagation Delay and the PDP at different levels of Power Supply and Temperatures. The power consumption of the proposed 10 nm CNTFET 8-T MGDI Full Adder at 27°C is 1.96 nW. The proposed CNTFET FA exhibits 60.32% improvement in Power Consumption when compared to the existing 10 nm FINFET 8-T MGDI Full Adder. The propagation Delay of the proposed FA is 42.16 ps and an improvement of 57.68% is noticed over the existing FA. The Power Delay Product of the proposed 10 nm CNTFET 8-T MGDI FA is 82.63 × 10−21 Jules, whereas the PDP of the 10 nm FINFET 8-T MGDI FA is 492.07 × 10−21 Jules. The PDP of the proposed 10 nm CNTFET 8-T MGDI Full Adder exhibits 83.21% improvement when compared to the 10 nm FINFET 8-T MGDI FA. [ABSTRACT FROM AUTHOR]

A chemical graph is a molecular complex that significantly explains the molecular structres. In this way atoms are identified by vertices and that are connected by lines known as edges of graph. Triangular benzenoids and starphene nanotubes are an inorganic compound with trigonal crystal system. We have computed the degree-based topological co-indices of triangular benzenoids and starphene nanotubes, that are successfully linked with its thermodynamic properties. [ABSTRACT FROM AUTHOR]

In this study, Ce and Mn co-doped SnO2–Sb electrode was prepared onto a Ti/TiO2 nanotubes surface. The nanostructure of the novel electrode was characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), and specific techniques were used to study the electrochemical characteristics of the electrode. SEM analysis results showed that TiO2 nanotubes could reduce the crack morphology and provide a larger surface area for loading the electrochemically active material. EDS analysis showed that Ce and Mn were doped into the electrode successfully. Under optimised conditions, the electrode prepared with Sn:Sb:Ce:Mn mole ratio of 100:10:3:3 has the best electrocatalytic performance. Ethylene glycol was used as the solvent in cerium-manganese co-doped Ti/TiO2–NTs/TiO2–SnO2–Sb electrode. Ce–Mn co-doped TiO2NTs/SnO2–Sb electrode has a high oxygen evolution potential of 1.79 V (vs. SCE) and a lower charge transfer resistance. The decolourisation extent of 30 mg L−1 methylene blue wastewater reaches 98.5% within 30 min. Finally, the main intermediates were identified by gas chromatography-mass spectrometer (GC-MS), and possible pathways for dye degradation were proposed. This study opens a door to the rapid electrochemical decoloursation treatment of wastewater by using an easily obtainable multi-metal co-doped electrode. [ABSTRACT FROM AUTHOR]

Carbon nanotubes have been actively studied for their applications in filtering of polycyclic aromatic hydrocarbons, sensors, electronics, stretchable devices, and energy storage. The large structures of nanotubes are studied using their induced subgraphs. The partition dimension focusses on the unique distance-based representation of nodes with respect to partition sets such that each node is exclusively identified. The partition and 2 − partition dimension of induced subgraphs of certain nanotubes have been computed in this article. [ABSTRACT FROM AUTHOR]

In this paper, halloysite nanotubes (HNTs) are used to enhance the bonding properties and water resistance of soy protein adhesives. HNTs are modified by KH560 marked as KH560-HNTs and dispersed in the adhesive matrix by ultrasonic-mechanical combination meanly, exploring the optimal addition amount of KH560-HNTs in the adhesive matrix and preparing a nanocomposite adhesive with uniform texture and exceptional properties. The results show that KH560-HNTs can significantly improve the bonding strength and thermal stability of SPI. The optimal addition of KH560-HNTs is 2%, meanwhile, the dry and wet bonding strengths are 1.63 MPa and 1.44 MPa, which increased by 34.71% and 102.82%, respectively, compared with that of soybean protein adhesive (SPI-0). Therefore, KH560-HNTs can be used to prepare environmentally friendly and excellent performance soy protein adhesives. In addition, the results can provide a research basis for the preparation of functional soy protein adhesives by loading additives in HNTs. [ABSTRACT FROM AUTHOR]

Molybdenum disulphide (MoS2) is a versatile inorganic material due to its unique electronic, electrical, optical, and biological properties, hence widely studied for various engineering applications. The main objective of this review is to provide comprehensive information about MoS2 for the researcher intended to start research on MoS2. The beginning of the review is focused on providing information on the methods, precursors, and conditions used for the synthesis of various MoS2 nanostructures such as nanospheres, nanotubes, nanoflakes, nanobelts, nanoflowers, nanofibers, nanoclusters, nanosheets, and nanowires. The structural features of MoS2, both in pure and with other composite forms, are discussed in detail using the XRD, Raman, PL and UV–visible spectra reported by various research groups. Further, the detailed morphological features of both pure and composite forms of MoS2 are also discussed by taking selected works of SEM and TEM images. Finally and very importantly, the review also summarises the multifunctional applications of the versatile MoS2 and its composites in lubricants, exploring its tribological properties, in lithium-ion batteries, revealing its electrical and electronic property, as a catalyst for water splitting hydrogen evolution reaction, oxygen evolution reactions, endorsing its potential electrochemical property, various biomedical applications such as bio sensors, bioimaging, and very importantly in environmental applications. Graphical Abstract is Reproduced with permission from [1] [2], [3]. [ABSTRACT FROM AUTHOR]

lithium titanate (LTO), which has spinel structure, has become one of the most popular anode materials for lithium-ion batteries because of its high safety and stability. In this paper, industrial metatitanic acid and lithium hydroxide were used as the main raw materials to prepare nanotube LTO materials by two-step hydrothermal method. The effects of different titanium sources, stirring speed, hydrothermal reaction temperature and time, li-ti molar ratio and other process parameters on the phase, morphology and electrochemical properties of the samples were studied. The experimental results show that the nanotube LTO electrode material can be prepared by stirring at 300 rpm, reacting at a hydrothermal temperature of 170 °C for 20h, controlling the lithium titanium molar ratio of 0.85, and finally calcining; The specific capacity of nanotube LTO reaches 150mah/g at 10 C high magnification, and the capacity retention rate of 500 cycles is more than 92%. Compared with ordinary LTO materials, nanotube LTO has obvious performance advantages and excellent comprehensive electrochemical performance. [ABSTRACT FROM AUTHOR]

Cyclacene carbon nanobelts represent the last unsynthesized building blocks of carbon nanotubes and are the shortest possible hydrogen capped nanotubes of zigzag type. Recent theoretical predictions indicate that stable cyclacene isomers containing Dewar benzene derived structures may exist. The properties of the Hückel-[n]cyclacene nanobelt complexes containing alkali metal and halide ions (n = 5-8), with zero to two Dewar benzenoid structures present, and transition metal complexes (n = 6, 8) with zero and two Dewar structures present, have been calculated using density functional theory. The halides, alkali metals, and transition metals were initially placed centrally within the belt cavities, and binding interactions have been observed for both positive and negative ions. The most stable isomeric forms are found to change for several of the belt sizes, depending on which ions are present. Internal transition metal sandwich complexes with η6-haptic bonds are also indicated to form within the cyclacene belts containing two Dewar benzenoids. [ABSTRACT FROM AUTHOR]

The development of multi-functional nanomaterials is nowadays more than a necessity to address both energy and environmental needs of our society. In this perspective, the hybridization of graphene (Gr) with TiO2 nanotubes (TiNT) is very promising to meet these issues. In the present work, bi-functional graphene-modified TiO2 nanotubes electrodes (Gr/TiNT) were successfully prepared. A simple and effective approach for graphene production, by electrochemical exfoliation of pure graphite foil in inorganic salt (Na2SO4) is used. Graphene sheets were formed on the surface of TiO2 nanotube arrays through electrodeposition process by chronoamperometry. Mesoporous graphene of high surface area is promising material for photocatalytic applications. Gr/TiNT electrode displays significantly improved photodegradation efficiency to MB, achieving a degradation percentage of 60% in 2 hours, which is about 50% higher than that of TiNT. Moreover, Gr/TiNT with high conductivity demonstrated good capability to deliver extremely high energy and power in a very short period of time, the relaxation time constant was only about 48 ms, which is far lower than that of most conventional activated carbon-based electrochemical capacitors. Capacitance retention of 98% was also demonstrated after 1000 cycles. [ABSTRACT FROM AUTHOR]

Arrays of TiO2 nanotubes were prepared on pre-deformed commercially pure titanium (Cp–Ti) foils by anodic oxidation in 1 vol.-% HF-based electrolyte. Prior to the anodic oxidation, the samples were deformed by uniaxial tension and cold rolling at room temperature in three different strain levels. Following the anodic oxidation, the samples were annealed at 450°C to obtain crystalline anatase structure. Effects of the deformation on the produced nano structures were investigated by characterisation studies and photocatalytic activity tests including methylene blue degradation test, photoluminescence, and UV–Vis diffuse reflectance spectra analyses. The results showed that the induced strain has a remarkable effect on the nanotube morphology. It also led to a decrease in the crystallite size in the uniaxial tensioned and cold rolled titanium foils. As a result of the morphological and structural changes, the photocatalytic activity of the samples increased with cold rolling strain, and uniaxial tension strains up to a critical level. [ABSTRACT FROM AUTHOR]

Zinc Oxide (ZnO) has a huge potential in absorbing light quanta and solar spectrum. Being an appealing semiconductor, ZnO has been synthesized widely to escalate its ability as a nanostructure. In this review, nanostructures of ZnO have been studied as a means to provide simple approaches using anodization. 1 D nanostructures of nanorods, nanotubes and nanowires, and 3 D nanostructures of nanoflowers are chosen due to these dimensional structures synthesized thrivingly via anodization. Observations were made on parameters of times, voltages, and electrolyte concentration. The enlightenment of these synthesis presents the simple approaches and understanding to be imposed on for future endeavor. [ABSTRACT FROM AUTHOR]

Titanium surface treated with titanium oxide nanotubes was used in many studies to quantify the effect of surface topography on cell fate. However, the predicted optimal diameter of nanotubes considerably differs among studies. We propose a model that explains cell adhesion to a nanostructured surface by considering the deformation energy of cell protrusions into titanium nanotubes and the adhesion to the surface. The optimal surface topology is defined as a geometry that gives the membrane a minimum energy shape. A dimensionless parameter, the cell interaction index, was proposed to describe the interplay between the cell membrane bending, the intrinsic curvature, and the strength of cell adhesion. Model simulation shows that an optimal nanotube diameter ranging from 20 nm to 100 nm (cell interaction index between 0.2 and 1, respectively) is feasible within a certain range of parameters describing cell membrane adhesion and bending. The results indicate a possibility to tune the topology of a nanostructural surface in order to enhance the proliferation and differentiation of cells mechanically compatible with the given surface geometry while suppressing the growth of other mechanically incompatible cells. [ABSTRACT FROM AUTHOR]

The DTA signal was studied in comparison with X-ray phase analysis of potassium nitrate particles in carbon nanotubes. It is shown that, for potassium nitrate particles in nanotubes, the temperature range of the existence of the KNO3 ferroelectric phase expands up to 300 K and the ferroelectric and low-temperature paraelectric phases coexist. [ABSTRACT FROM AUTHOR]

A set of Fe-Mo-Mg catalysts with varying Mo/Mg weight ratios (40/10, 30/20, 20/30, and 10/40) were prepared and evaluated for the synthesis of graphene nanosheets/carbon nanotubes (GNS/CNT) hybrid materials via methane chemical vapor deposition. The results showed that changing the Mo/Mg ratio had a significant impact on the yield and the nature of the deposited carbon. The XRD and TPR results revealed that the iron molybdate and magnesioferrite species were the main components of Fe-Mo-Mg catalysts. TEM images showed that GNS-CNT hybrid materials were successfully grown on the surface of all Fe-Mo-Mg systems, except for the catalyst with the Mo/Mg ratio of 10:40, which produced CNT only. Raman spectroscopy results revealed that all carbon products were of high quality, with ID/IG ratios ranging from 0.14 − 0.41. It was also noticed that increasing the MgO content in the catalyst composition increases the amount of CNT compared to GNS. The total carbon yield increased from 170% to 284% for Fe-40Mo-10Mg and Fe-10Mo-40Mg, respectively. The gradual incorporation of Mg into the Fe-Mo catalyst significantly increased catalytic growth activity due to the presence of numerous mixed oxide species with diverse structures, such as MgFeOx, MgMoOx, and FeMoOx. [ABSTRACT FROM AUTHOR]

Nowadays, carbon nanotubes (CNTs) due to their inorganic conducting, semiconducting, and organic π-π stacking properties are becoming innovative materials. CNTs have an adjustable size, large surface area, and other significant chemical properties. Due to their excellent electrical, optical, and mechanical properties, CNTs play an important role in various application fields. In the past decade, many unique intrinsic physical and chemical properties have been intensively explored for pharmaceutical, biological, and biomedical applications. The functionalization of CNTs results in a remarkably reduced cytotoxicity and at the same time increased biocompatibility. The toxicity studies reveal that highly water-soluble and serum stable nanotubes are biocompatible, nontoxic, and potentially useful for biomedical applications. Ultrasensitive drug determination from its dosage form and/or biological samples with carbon nanotubes can be realized after surface modification. The main purpose of this review is to present recent achievements on CNTs which are investigated in electrochemical and chromatographically sensing technologies. [ABSTRACT FROM AUTHOR]

A topological index is a numerical value associated with a graph structure that has some correlation with corresponding physical property, chemical reaction or biological activity. To achieve much information and less degeneracy, many kinds of topological indices are defined on distances, degrees, countings, spectrums, etc. In this paper, we mainly study the edge-hyper-Wiener which is the distance-based index. It is the sum of the distances and the square of distances between all pairs of edges. Further, the exact expression of the edge-hyper-Wiener index of the zigzag single-walled nanotubes is given. [ABSTRACT FROM AUTHOR]

The tensile properties and fracture mechanism of hydroxyl-functionalized silicon carbide nanotubes (O-fSiCNTs) inserted into polymer matrices are explored and the outcomes are compared to results for the hydroxyl-functionalized carbon nanotubes (O-fCNTs) incorporated in similar matrices. The molecular dynamics (MD) method is used and the simulations are based on the notion of representative volume elements (RVEs). The incorporation of chemisorbed nanotubes in polymers has a profound effect on the enhancement of their mechanical properties. The O-fSiCNTs inside the polyethylene (PE) and polypropylene (PP) (O-fSiCNTs/PE and O-fSiCNTs/PP) possess lower Young's modulus, maximum stress, and strain energy as compared to the O-fCNTs/PE and O-fCNTs/PP. The zigzag O-fSiCNTs/polymer experiences lower bearable maximum strains in response to imposed loads in comparison with the O-fCNTs/polymer which is opposite to what occurs in the armchair O-fSiCNTs and O-fCNTs/polymer. The more the functionalization degree is, the weaker the structure is and its stiffness, tensile strength, tolerable strain before fracture, and ability to absorption of internal energy decline. Not only are the zigzag O-fSiCNTs/polymer stiffer than the armchair O-fSiCNTs/polymer in every percent of functionalization, but also as compared to the armchair ones, they show a lower decrease in the variation of Young's modulus with increasing the functionalization percentage. [ABSTRACT FROM AUTHOR]

We scrutinise the adsorption of cyclohexylamine (CHA) on pure and Cu-doped BN-nanotube (Cu@BN-NT) through density functional theory calculations. CHA had a weak interaction with the pristine BN-NT, making BN-NT not suitable to be used as a sensor. However, there was a substantial rise in the reactivity and sensitivity of the BN-NT after replacing the B with metal Cu, based on the standard Gibbs free energy of formation. There is a reduction in the energy gap of the HOMO–LUMO of Cu@BN-NT from 2.28 to 1.42 eV (∼ −37.7%) when CHA was adsorbed, which substantially increased the electrical conductivity. Hence, converting the substantial change in the electrical conductivity into an electronic signal was possible, which demonstrated that the Cu@BN-NT was an encouraging sensor to detect CHA. The computed recovery time for the Cu@BN-NT was 26.8 s, which is short. [ABSTRACT FROM AUTHOR]

In this study, the possibility of percolation system conductivity control by the applied electric field has been researched based on computer simulation and experimental measurements of electrical characteristics of liquid crystal–carbon nanotubes nanocomposite. It was found that electrical resistance of obtained nanocomposites decreases with increasing nanotube concentration. It is shown that the applied voltage reduces the resistance of the nanocomposite, which is likely associated with the change in the spatial orientation of nanotubes. Nanocomposites with 2–4% nanotube content show the maximum field-controlled relative change in resistance. The effect of concentration and orientation of the nanotubes on the percolation processes in the carbon nanotube system has been studied by computer simulations. The change in the percolation probability was revealed when limiting nanotube orientation angles that are controlled by the electrical field. [ABSTRACT FROM AUTHOR]

This article is a comprehensive investigation into the equations of the size-dependent free vibration of a special type of fluid-conveying nanotubes, i.e., double-walled boron nitride nanotubes, in a thermal environment. The motion equations are obtained through the use of nonlocal strain gradient theory for piezoelectric materials combined with the first-order shear deformation theory and Hamilton's principle. Lennard-Jones potential function imposes the coupling between the pair of nanotubes that are bound together via van der Waals forces. This study also considers softening and hardening effects to better understand important aspects of modeling. After setting proper boundary conditions, the differential quadrature method is exploited to solve the obtained equations. This numerical study allows us to evaluate the effects of many parameters that include delta-temperature, aspect ratio, size scale and boundary conditions on the nondimensional eigenfrequency of considered system and critical flow velocity. [ABSTRACT FROM AUTHOR]