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• Asymmetric vdWs structure based on CNT was established and it was studied by NEMD. • Temperature can easily break through the vdWs interaction at small layer spacing. • Large layer spacing hinders temperature-induced disruption of vdWs interactions. • Medium layer spacing maximizes TR ratio (757 %) at a specific temperature. • Changing the chiral combination makes the peak of TR move to the normal temperature. Van der Waals (vdWs) heterojunctions constructed from double/single-walled carbon nanotubes (DSCNTs) demonstrate exceptional thermal rectification (TR) ratios, coupled with a straightforward fabrication process, making them highly suitable for thermal rectifier applications. In this study, we employed a Nonequilibrium Molecular Dynamics method to investigate the heat flux and TR across DSCNTs with varying interlayer spacings. Our findings reveal that at smaller interlayer spacings, high temperatures readily overcome vdWs interactions. Conversely, increasing the interlayer spacing initially impedes this effect, though elevated temperatures can surmount this barrier. Significantly, at specific combinations of temperature and interlayer spacing, the left side in DSCNTs establishes interlayer phonons transport channels, facilitating forward heat flux but impeding the backward. This mechanism results in an exceptionally high TR ratio, reaching up to 757 %. Additionally, altering the chiral configurations of the CNTs in the inner and outer layers, while preserving interlayer spacing, further enhances the TR ratio and reduces the temperature threshold required to achieve peak TR ratio. Our findings contribute valuable insights into the phonon transport mechanisms within one-dimensional vdWs heterojunctions. [Display omitted] [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h -BN) is considered a very promising anti-friction material, however, how to assemble them densely and uniformly on metal surfaces remains a challenge. In this study, CNT-assisted plasma electrolytic oxidation (PEO) with the addition of h -BN nanoparticles was employed to create a double-layer coating on titanium alloy, demonstrating exceptional tribological characteristics. The CNTs not only acted as lubricating phases to improve the anti-friction performance but also as additives to facilitate the transition from the nanocomposite coating to the double-layer coating. The later stage of the PEO process with CNT doped in the electrolyte produces an interesting sudden rise in current density, which generates strong and dense discharge that facilitates the deposition and sintering of h -BN. As a result, the double-layer coating has a higher adhesion and hardness as well as more h -BN nanoparticles incorporated into the coating compared to coatings without CNTs-assisted deposition. Further, the double-layer coating exhibits a lower friction coefficient (∼ 0.11), attributed to the high release rate of h -BN under shear to form a lubrication film in conjunction with CNTs on the contact surface. The simple technique offers a novel approach to fabricating self-lubricating ceramic coatings on light alloys, which has huge potential for application in the anti-friction materials field. [Display omitted] • CNT-assisted PEO method achieves dense TiO 2 -hBN/CNT double-layer coating. • The coating exhibits low COF (∼0.11). • Simple method offers potential for self-lubricating coatings on light alloys. [ABSTRACT FROM AUTHOR]

[Display omitted] • We study the ITRs of AlN/graphene/SiC heterostructures by molecular dynamics simulation. • The ITRs decrease with the increase of the numbers when the height of the NNFSs is lower than the cutoff distance. • The ITRs increase significantly when the height of the NNFSs is higher than the cutoff distance of the interaction. • The change of the ITRs arises from the combined effect of sub-interfacial interactions and the overlaps of PDOS. Revealing the heat transport mechanism in typical heterostructures is crucial for designing GaN power chips with better engineering heat transfer performance. Herein, the effect of nanoscale nonplanar feature structures (NNFSs) on the interfacial thermal resistances (ITRs) of w-AlN/bilayer graphene/3C-SiC heterostructures is investigated systematically by molecular dynamics. The results indicate that the increase of the NNFSs numbers contributes to the decrease of the ITRs when the height is lower than the cutoff distance of the interaction. Multiple analyses indicate that, although the interactions at two van der Waals sub-interfaces (w-AlN/graphene and graphene/graphene) slightly weaken the phonon transfer, the increase of the NNFSs numbers enlarge the overlaps of phonon density of state (PDOS), which provides more phonon transfer channels. However, when the height is higher than the cutoff distance, the ITRs increase significantly due to the double decrease of the interactions and the overlaps of PDOS for the w-AlN/graphene sub-interface. These phenomena are further verified by the transient transport of energy. Besides, the NNFSs with random distribution also contribute to the reduction of the ITRs. We believe that the results of this work will provide significant guidance for improving the thermal transport performance of GaN power chips. [ABSTRACT FROM AUTHOR]

In this study, a hybrid nanomaterial based on layered double hydroxides (LDH) and multi-walled carbon nanotubes (MWCN) was fabricated using a co-precipitation method. Trisodium phosphate (TP) was loaded into the designed nanocarrier to enhance the corrosion resistance of mild steel in 3.5 wt% NaCl media. Fourier transform infrared (FT-IR) spectroscopy, Raman, and X-ray diffraction (XRD) analyses were carried out to investigate the magnesium‑aluminum layered double hydroxides/oxidized-multiwalled carbon nanotubes (Mg-AL-LDH/O-MWCN) structure and morphology before and after loading of trisodium phosphate. Furthermore, the nanocarrier inhibition capability was evaluated through electrochemical impedance spectroscopy (EIS), polarization, and field emission-scanning electron microscopy (FE-SEM) techniques. Electrochemical impedance spectroscopy (EIS) was also employed to estimate the anticorrosion properties of the epoxy coating loaded with TP-LDH/O-MWCN. The EIS evaluation of the intact coating revealed the impedance at the lowest frequency (|Z| 0.01 Hz) of about 109 Ω.cm2 after 42 days of immersion for the trisodium phosphate-layered double hydroxides/oxidized-multi-walled carbon nanotubes@epoxy (TP-LDH/O-MWCN@EP) sample and the lowest value of breakpoint frequency was obtained for this sample (f b = 0.063 Hz). These findings prove the trisodium phosphate-layered double hydroxides/oxidized-multi-walled carbon nanotubes (TP-LDH/O-MWCN) particles' effectiveness in the epoxy coating water/ion barrier function enhancement. EIS results indicated the enhancement of the charge transfer resistance (R ct) of the scratched coatings, from 65.97 kΩ.cm2 for the pure epoxy (EP) sample to 94.87 kΩ.cm2 for the trisodium phosphate-layered double hydroxides/oxidized-multi-walled carbon nanotubes@epoxy (TP-LDH/O-MWCN@EP) sample, revealing the self-repairing behavior of the designed coating. In addition, the adhesion properties of the samples coated with LDH/O-MWCN@EP and TP-LDH/O-MWCN@EP were studied by pull-off and cathodic disbonding tests, leading to a 33% reduction in adhesion loss and a 52.23% reduction in the diameter of cathodic delamination. The tensile test conducted on the samples indicated an increase in the ultimate tensile strength (σ UTS), elongation break (Ɛ b), and toughness values by 188%, 223%, and 800%, respectively, in comparison with the pure epoxy (EP) sample. • Hybrid nanocarriers based on Mg-Al-LDH decorated multi-walled carbon nanotubes (MWCN) were produced. • Phosphate-loaded LDH/OMWCN nano-hybrid effectively declined mild steel corrosion in saline media via ion-exchange mechanism. • Both barrier and active anti-corrosion function of epoxy coating were promoted after adding Phosphate-loaded LDH/OMWCN nano-hybrid. [ABSTRACT FROM AUTHOR]

Wearable flexible strain sensors have prospective application prospects in human motion monitoring, human-computer interaction, and information transmission. However, facilely manufacturing flexible strain sensors with a high sensitivity and extended sensing range remains challenging. Herein, a flexible strain sensor with a double percolation structure was prepared through simple melting mixing and biaxial stretching. To this end, carbon nanotubes (CNTs) filled styrene butadiene styrene (SBS) and polyolefin elastomer (POE) were employed as the conductive and insulating phases, respectively. The effects of biaxial stretching on sensor performance were systematically studied. During biaxial stretching, the as-obtained CNT-SBS/POE nanocomposites with double percolation structure exhibited better processing performance and stability than conventional CNT-SBS binary composites. Biaxial stretching results in better dispersion and planar orientation of CNTs in polymers, improving the sensing property of strain sensors. The optimized stretching ratio of double percolation structured composites was determined as 1.5, with 3 wt% CNT-SBS/POE sensor exhibiting high sensitivity (gauge factor = 7501.69) over a wide strain monitoring range (0–300% strain). Additionally, the flexible strain sensors could monitor physiological activities and information transmission with good reliability, thereby promising for human-machine interaction, wearable, and medical monitoring. [Display omitted] • Double percolation structure can reduce the percolation threshold of composite materials. • Biaxial stretching can improve the orientation arrangement of CNT nanofillers in SBS phase. • Biaxial stretching can improve the strain sensing and mechanical properties of composite materials. • CNT-SBS/POE-1.5 sensor with a stretching ratio of 1.5 exhibits excellent sensitivity and stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Technology for the controlled formation of strain-free ZB-GaN QDs on Si is shown. • The key aspect of the technology is the use of van der Waals g-SiN layer. • Ga droplets are formed on the g-SiN surface in a controlled manner. • During the GaN QDs formation, the initial set of droplet parameters is maintained. • GaN QDs with g-SiN/Si(1 1 1) are suitable for nanoelectronic and nanophotonic devices. GaN quantum dots (QDs) have enormous potential for applications in science and technology, but their optimal use requires precise control of parameters such as density, size and monodispersity. To address this issue, we use the conventional method of forming QDs – droplet epitaxy, on the unconventional surface – graphene-like SiN formed on Si(1 1 1). When droplet epitaxy is used on conventional surfaces such as Si(0 0 1), Si(1 1 1), SiO 2 , or Al(Ga)N, there is material exchange between droplets during crystallization, which makes it difficult to control parameters and form monodisperse QDs. The atomically smooth surface of g-SiN with weak van der Waals interactions allowed us to nucleate Ga droplets in a controlled manner. Meanwhile, amorphization of the g-SiN layer during the droplet crystallization process allowed us to suppress material exchange between the droplets, resulting in QDs with a narrow size distribution. Structural analysis revealed unstrained QDs with a zinc-blende structure due to weak bonding between the QDs and the g-SiN layer. Overall, the proposed method provides a way to grow unstrained and monodisperse ZB-GaN QDs on an accessible substrate with control over their density and size, which is particularly important for the widespread application of GaN QDs. [ABSTRACT FROM AUTHOR]

• Two slender CFST double-column piers are tested under cyclic loading. • The prefabricated connections guarantee the performance of the novel pier system. • FE modeling is carried out to assess seismic performance of pier systems. • The novel pier systems have application potential in bridges of mountain areas. This paper investigates the seismic behavior of a prefabricated thin-walled concrete-filled steel tubular (CFST) pier system composed of circular thin-walled CFST double-column, I-shaped steel beam, and precast reinforced concrete (RC) cap beam. Hysteretic tests were conducted on two slender double-column pier systems: one with prefabricated connections (prefabricated pier system), and the other one with traditional embedded connections (traditional pier system). The test results indicated that, compared with the traditional pier system, the pier system with prefabricated connections demonstrating an 18 % increase in lateral resistance and a 5 % higher ductility coefficient, despite the weld of the steel beam cracked prematurely. Finite-element numerical models were established based on the OpenSees platform and validated by the cyclic loading tests. A comprehensive investigation involving a total of 12 cases, encompassing both CFST piers and RC piers, was conducted to evaluate their seismic performance and economic efficiency. The analysis results revealed that the proposed prefabricated pier system offers notable advantages in seismic performance for both tall and low piers. [ABSTRACT FROM AUTHOR]

The demand for sustainable semiconducting devices that can be used in various applications necessitates the development of revolutionary materials with multifunctional properties. Using van der Waals interactions corrected first-principles density functional theory (DFT) calculations, we propose porous g-XO (X = Ge, Cu) inorganic graphenylene monolayers. These monolayers extend the family of synthesized porous organic graphenylene materials. Stability checks reveal that the g-XO monolayers are energetically, mechanically, dynamically, and thermally stable. Additionally, g-GeO monolayer is auxetic 2D material. The auxetic property of g-GeO monolayer could be advantageous for important applications in mechanics and tissue engineering, electromechanical devices, and flexible electronics. Based on the HSE06 electronic band structure results, these g-CuO and g-GeO monolayers exhibit wide and ultra-wide indirect bandgap semiconducting properties, respectively. The satisfactory absorption coefficient of 10 4 –10 5 cm−1 spanning the visible to UV region implies their potential for optoelectronics and UV shields applications. Our theoretical results provide a hints for the potential of these porous g-XO monolayers in energy harvesting/conversion, nanofiltration membranes, optoelectronic, thermoelectric, and flexible electronics. [Display omitted] • The porous g-XO (X = Ge, Cu) monolayers have been investigated using DFT calculations. • g-XO monolayers are energetically, mechanically, dynamically, and thermally stable. • g-GeO monolayer is auxetic 2D material. [ABSTRACT FROM AUTHOR]

Experimental and numerical studies on flexural behaviour of rectangular double-opening concrete filled sandwich steel tube (DCFSST) beams were performed in this study. Six specimens under different cross-section of inner tube and nominal cross-sectional steel ratio (α n) were tested under bending to assess the failure modes, moment-displacement and moment-strain relationships, flexural capacity and flexural stiffness of rectangular DCFSST beams. The experimental results demonstrate that the two design variables investigated in this paper have limited impact on the failure modes of typical specimens. The failure mode of outer tube includes multiple local bulges on top flange and one case of fracture on bottom flange that is located at the same plane as the primary local bulge on top flange, whilst the failure mode of inner tubes is mainly due to excessive global deflection. Simultaneously, sandwich concrete is crushed at the locations with evident local bulge on outer tube and cracks nearly uniformly within the lower 2/3 section depth. In general, the flexural capacity and stiffness of the specimens enhance as α n increases, and are moderately affected by the cross-section of inner tube. In addition, finite element (FE) models were built to replicate the flexural behaviour of rectangular DCFSST beams, and the FE models were validated by comparison with test results. At the end of the paper, simplified formulae that can better predict the flexural capacity of rectangular DCFSST beams were developed. • Typical tests of rectangular DCFSST beams under bending were carried out. • FE models that can well reproduce the flexural behaviour of rectangular DCFSST beams were developed. • Formulae that can accurately predict the flexural capacity of rectangular DCFSST beams were proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrode material with efficient and selective phosphate adsorption was developed. • ZnFe-PANI/CNT electrode exhibited remarkable capacitive behavior and charge storage capacity. • ZnFe-PANI/CNT had excellent phosphate adsorption capacity over a wide parameters range. • The high phosphate removal rate was maintained after 10th regeneration processes. Capacitive deionization technology possesses puissant competitiveness in the field of water treatment due to its low cost and high efficiency. In this study, polyaniline (PANI) doped and carboxyl intercalated metal hydroxide composite (ZnFe-PANI/CNT) was developed by a simple co-precipitation method, and used as anode electrode for phosphate removal in sewage. The results show that ZnFe-PANI/CNT electrode can efficiently remove phosphate at concentration of 2–10 mg/L at a wide range of pH (3–10) by electric double layer capacitive adsorption and pseudocapacitive adsorption. The concentration of phosphate in the effluent was as low as 0.095 mg/L, and the coexisting anions (Cl−, NO 3 −, SO 4 2− and HCO 3 −) hardly inhibited the phosphate adsorption by ZnFe-PANI/CNT composite electrode. In addition, under the optimal phosphate adsorption conditions (pH = 7 and applied voltage of 1.2 V), the energy consumption of CDI system was calculated as low as 0.00274 kWh/g P and 0.017 kWh/m3 water, realizing the expectation of low cost and high efficiency operation. [ABSTRACT FROM AUTHOR]

The most pressing issue now is to improve the cooling process in an electrical power system. On the other hand, nanofluids are regarded as reliable coolants owing to their exceptional characteristics, which include excellent thermal conductivity, a faster heat transfer rate, and higher critical heat flux. Considering these fascinating properties of nanofluid, this research looks at the flow of mineral oil based Maxwell nanofluid with convective heat. Moreover, introducing heat radiation, viscous dissipation and Newtonian heating add to the novelty of the problem. The coupled partial differential equations supported by the accompanying boundary conditions are numerically solved using an implicit finite difference method. The simulations are carried out using MATLAB software, and the obtained results are illustrated graphically. It is observed that the velocity of fluid increases concernign the relaxation time parameter but decreases against fractional derivative. [ABSTRACT FROM AUTHOR]

Proper control of a 3d transition metal-based catalyst with advanced structures toward oxygen evolution reaction (OER) with a more feasible synthesis strategy is of great significance for sustainable energy-related devices. Herein, carbon nanotube interconnected NiCo layered double hydroxide rhombic dodecahedral nanocages (NiCo-LDH RDC@CNTs) were developed here with the assistance of a feasible zeolitic imidazolate framework (ZIF) self-sacrificing template strategy as a highly efficient OER electrocatalyst. Profited by the well-fined rhombic dodecahedral nanocage architecture, CNTs' interconnected characteristic and structural feature of the vertically aligned nanosheets, the as-synthesized NiCo-LDH RDC@CNTs integrated large exposed active surface areas, enhanced electron transfer capacity and multidimensional mass diffusion channels, and thereby collaboratively afforded the remarkable electrocatalytic performance of the OER. Specifically, the designed NiCo-LDH RDC@CNTs exhibited a distinguished OER activity, which only required a low overpotential of 255 mV to reach a current density of 10 mA cm−2 for the OER. For the stability, no obvious current attenuation was detected, even after continuous operation for more than 27 h. We certainly believe that the current extraordinary OER activity combined with the robust stability of NiCo-LDH RDC@CNTs enables it to be a great candidate electrocatalyst for economical and sustainable energy-related devices. [ABSTRACT FROM AUTHOR]

Floating catalyst chemical vapor deposition (FCCVD) has been one of the most important techniques for the synthesis of high‐quality single‐, double‐, and multi‐wall carbon nanotubes (CNTs). The method is characterized of simple processing, good controllability, and desirable scalability. The bulk morphologies of the synthesized CNTs can be sponge‐like, an array, a thin film, or fiber by simply changing the growth parameters and the way they are collected, which facilitates a wide range of applications. The authors comprehensively review the state‐of‐the‐art progress on the controlled growth of CNTs by FCCVD which have a defined number of walls, and controlled diameter, bundle size, and type of conductivity. The properties and possible applications for the CNTs and their hybrids are summarized. Finally, insights into the key challenges and prospects for CNTs synthesized by FCCVD are discussed. [ABSTRACT FROM AUTHOR]

Strong intertube excitonic coupling is demonstrated in 1D van der Waals heterostructures by examining the ultrafast response of radial C/BN/MoS2 core/shell/skin nanotubes to femtosecond infrared light pulses. Remarkably, infrared excitation of excitons in the semiconducting carbon nanotubes (CNTs) creates a prominent excitonic response in the visible range from the MoS2 skin, even with infrared photons at energies well below the bandgap of MoS2. Via classical analogies and a quantum model of the light–matter interaction these findings are assigned to intertube excitonic correlations. Dipole–dipole Coulomb interactions in the coherent regime produce intertube biexcitons, which persist for tens of femtoseconds, while on longer timescales (>100 ps) hole tunneling—from the CNT core, through the BN tunnel barrier, to the MoS2 skin—creates intertube excitons. Charge transfer and dipole–dipole interactions thus play prominent roles on different timescales, and establish new possibilities for the multi‐functional use of these new nanoscale coaxial cables. [ABSTRACT FROM AUTHOR]

Double-walled metal pipes are important components for heat exchange and liquid transportation. They can be manufactured by mechanical drawing of two concentric pipes. In this work, a mechanical model is developed to analyze the stress state evolution during the manufacturing process, and the criterion for forming the double-walled pipe was given under the ideal elastoplastic and thick-walled assumptions. The model also encompasses the results deduced under the thin-walled assumption. Numerical simulations confirmed that the accuracy of the analytical model was within 5%. The application on actual steel materials with various parameters varied, including the wall thickness and initial gap, was analyzed. This work can provide theoretical support to industrial manufacturing procedures and help to reduce costs by eliminating required test procedures. [ABSTRACT FROM AUTHOR]

A coupled load flow algorithm is developed to perform transmission and distribution (T&D) co-simulation. Subsequently, the effects of distributed energy resources (DERs) on the dynamics of power systems are studied by extending the T&D load flow algorithm to T&D dynamic co-simulation. The detailed distribution and transmission systems are modeled separately and are coupled at the substation nodes at each time step. Dynamics of the DER_A mechanisms are modeled separately downstream of the distribution substation using the North American Electric Reliability Corporation model (NERC-2018). The effects of the DER_A settings are examined on the dynamics of the transmission system and DER operation. In addition, lumped and distributed induction motor load models are compared at the distribution level. The results of the study show that under high DER penetration excessive operation may occur at the distribution load tap changers. Also, the effect of reactive power on voltage recovery is significant under DER high fault-ride-through capability and DER reactive current injections. Moreover, it is observed that DER frequency control may adversely affect the DER operation keeping the active and reactive currents at high levels due to frequency deviations. Finally, distributed induction motor loads stimulate more DER reactive power injection causing voltage overshoots. [ABSTRACT FROM AUTHOR]

• Semi-analytical method to study agglomerated CNT composite cylindrical panel considering non-local elasticity is presented. • Buckling and free vibration behaviours of agglomerated CNT nano composite panel under non-uniform edge load are presented. • Effects of non-local parameter, nature of agglomeration and non-uniform edge loadings are analysed. • The results obtained using the present approach are in good agreement with the results available in literature. A semi analytical nonlocal elasticity model to analyze the effect of non-uniform edge loads on static stability and free vibration characteristics of agglomerated carbon nanotubes (CNTs) reinforced nano cylindrical panels are presented. Effective material properties of the agglomerated CNT reinforced composite are obtained using a two-parameter micro-mechanics model while Eringen's non-local theory is used to account the size effect. Sinusoidal shear deformation theory is adopted to analyze the buckling and vibration parameters using Galerkin's approach. The accuracy of the proposed model is presented first by comparing the results in the literature. Then a comprehensive study is carried out to analyze the influence of various degrees of agglomeration (complete, partial), nature of edge load, and non-local effects on the buckling and free vibration response of CNT reinforced nano cylindrical panel. The results revealed that non-local size effect leads to a reduction in stiffness and thus reduces buckling and dynamic characteristics. Moreover, it is observed that critical buckling load varies with type of in plane load and reduction in natural frequency is different for different in plane loading conditions. [ABSTRACT FROM AUTHOR]

This article mainly studies the vibration of the carbon nanotubes embedded in elastic medium. A new novel method called the Hamiltonian-based method is applied to determine the frequency property of the nonlinear vibration. Finally, the effectiveness and reliability of the proposed method is verified through the numerical results. The obtained results in this work are expected to be helpful for the study of the nonlinear vibration. [ABSTRACT FROM AUTHOR]

Research indicates that single-walled carbon nanotubes have a unique coupled torsional–radial vibration as one of their fundamental modes. Determination of their vibration frequency is required for efficient use of single-walled carbon nanotube in nano-electromechanical systems. However, there is no mathematical expression for these frequencies and their dependence on single-walled carbon nanotube geometry is unknown. This article examines the effect of diameter, length, and chirality on the fundamental coupled torsional–radial vibration frequency of single-walled carbon nanotube using molecular–structural–mechanics–approach, finite element analysis, and regression analyses. Consequently, a first-ever mathematical form of this frequency is derived. The form quickly and accurately predicts these frequencies at 1.5% in-sample, and 7.2% out-sample mean absolute percentage error. single-walled carbon nanotubes' fundamental coupled torsional–radial vibration frequency is found independent of diameter and inversely proportional to length where the proportionality constant depends on chirality. The coupling of modes and the similarity of the frequency form with cylindrical shell suggest that single-walled carbon nanotube behave like thin shells in these vibrations. A form for effective circumferential shear modulus of single-walled carbon nanotube is also derived. This modulus is found to depend only on the chirality where achiral single-walled carbon nanotubes have higher values than chiral single-walled carbon nanotubes. Proposed mathematical forms can be used for characterization of single-walled carbon nanotubes, determination of single-walled carbon nanotubes' effective shear modulus, and tuning operational frequency of single-walled carbon nanotube-based nano-electromechanical systems. [ABSTRACT FROM AUTHOR]

Flow-induced vibration of carbon nanotubes becomes an important topic in nanotechnology. In our study, the non-linear vibrational behaviour of single-walled carbon nanotubes is presented. A singlewalled carbon nanotube is modelled as a simply supported beam embedded in the Winkler-Pasternak foundation. For the analysis, the Euler-Bernoulli beam theory is used to develop the model. This study uses a continuum approach which is widely employed for the dynamic behaviour of carbon nanotubes. The governing non-linear equation of motion is solved using the homotopy perturbation method. Elliptical functions are used to solve the exact solutions of these differential equations. The results of the exact solutions in terms of elliptic functions are compared to both the linear and nonlinear frequencies. Concerning changes in the Winkler and Pasternak parameters, axial force and flow velocity, the variation between linear and non-linear frequencies is studied. Furthermore, by adjusting these parameters, the non-linear vibrational frequency can be fine-tuned. [ABSTRACT FROM AUTHOR]

Transport and storage of liquefied natural gas (LNG) requires special double-walled cryogenic tanks. To provide a liquid state of LNG throughout entire storage time a temperature inside the tank should be equal −160 °C under the pressure of around 7 bar. Maintaining these parameters requires a vacuum insulation system and internal supports designed to minimize heat leakage into the tank. Additionally, the internal supports must be able to transfer complex mechanical loads that may occur during the operation of the tanker. Combinations and values of directional mechanical loads and thermal loads, to be accepted in designing mobile cryogenic tanks, are determined by proper vessels standards. In this article, we proposed the construction of internal supports for 25 m3 road tanker, which structure allows to reduce heat leakage into the internal tank, while transferring the complex mechanical loads. Tests of the presented solutions were carried out applying both mechanical and thermal finite element analysis using ANSYS software. [ABSTRACT FROM AUTHOR]

Composites of carbon nanotubes (CNTs) and lignin are promising and potentially cheap precursors of—to this day—expensive carbon fibers. Since the control of the CNT‐lignin interface is crucial to maximize fiber performance, it is imperative to understand the fundamental noncovalent interactions between lignin and CNT. In the present study a density functional theory study is conducted to investigate the fundamental noncovalent interaction strength between metallic (n, n) single‐walled CNT (SWCNT) and simple lignin model molecules. In particular, the respective adsorption energies are used to gauge the strength of interaction classes (ππ interaction, CHπ hydrogen bonding and OH‐related hydrogen bonding. From the data, substituent‐dependent interaction trends as well as class‐ and curvature‐dependent interaction trends are derived. Overall, we find that most of the interaction strength trends appear to be strongly influenced by geometry: flat orientation of the test molecules relative to the (n, n) SWCNT surface and small (n, n) SWCNT curvature—that is, large diameter enhances the CHπ and ππ interactions. [ABSTRACT FROM AUTHOR]

Tellurium, as an elemental van der Waals semiconductor, has intriguing anisotropic physical properties owing to its inherent 1D crystal structure. To exploit the anisotropic and thickness‐dependent behavior, it is important to realize orientated growth of ultrathin tellurium. Here, van der Waals epitaxial growth of Te on the surface of 2D transition metal dichalcogenides is systematically investigated. Orientated growth of Te with a thickness down to 5 nm is realized on three‐fold symmetric substrates (WSe2, WS2, MoSe2, and MoS2), where the atomic chains of Te are aligned with the armchair directions of substrates. 1D/2D moiré superlattices are observed for the Te/WSe2 heterostructure. This method is extended to the growth of SeTe alloys, providing flexibility for band engineering. Finally, growth of textured Te film is demonstrated on the lower‐symmetry surface of WTe2. [ABSTRACT FROM AUTHOR]

In this study, the hydroforming process parameters of a bi-layered X-type tube are designed and optimized by exploring the response surface methodology. First, UG software is used for model setup of the bi-layered X-type tube and mold, which is imported into DYNAFORM software for further numerical simulation and calculation of the hydroforming process. The main parameters of the loading path are selected as experimental factors for the methodology. The maximum thinning ratio of the inner and outer tubes, the maximum clearance between bi-layers, and the limit fillet radius of the top branch tube are used as test evaluation indicators. In accordance with effective evaluation indexes, perturbation plots, optimization evaluation criteria, and contour graphs, the relationship among the main influencing factors is analyzed and the process parameters of the optimal loading path are screened. Finally, a comparison between experimental results and simulation is made and shows that the error is within 6%, which indicates that the optimization method of the hydroforming process parameter in a bi-layered X-type tube has high feasibility. [ABSTRACT FROM AUTHOR]

Molecular configurations are some of the important factors that strongly affect the hydrogen adsorption in carbon nanotubes (CNTs). A Quantum Molecular dynamics simulations are performed to study the adsorption isotherm of torsional double-walled carbon nanotubes (DWCNTs) filled with hydrogen molecules. The considered key factors that affect the hydrogen storage responses of the DWCNTs are the adsorption energy and the surface tension effect. Our simulated results show that 2-sided effect is observed and kinetic diameter of H 2 molecules is shortened approximately 4.11% under helical confinement. The results further reveal that the amounts of hydrogen storage wt% are computed at 77 K and found to be 1.77 wt% and 3.92 wt% for pristine and twisted-DWCNTs, respectively. Finally, it is shown that the adsorption heat, which reflects surface property, is twisted dependent. • Results show that 2-sided effect is observed. • The kinetic diameter of H 2 molecules is shortened approximately 4.11% under helical confinement. • Results reveal that the amounts of hydrogen storage wt% are computed at 77 K and found to be 3.92 wt% for twisted-DWCNTs. • It is shown that the adsorption heat, which reflects surface property, is twisted dependent. [ABSTRACT FROM AUTHOR]

The mode-I and mode-II interlaminar fracture properties of high modulus pitch-based carbon fiber reinforced polymers (CFRPs) (fiber: K13C; resin: EX-1515 cyanate ester) modified with 20–30 nm β-SiC nanoparticles or multiwalled-carbon nanotubes (MWCNTs) were investigated. Different volume fractions of both the β-SiC nanoparticles (1, 2, 5, and 10 vol%) and MWCNTs (1, 3, 5, and 7 vol%) were tested. The values of the mode-I and mode-II interlaminar fracture toughness of the CFRPs containing the lowest volume fractions of these nanostructures were larger compared with the unfilled composite but decreased with increasing the volume fraction of the inclusions. No differences in mechanical properties were observed among the different nanostructure types. [ABSTRACT FROM AUTHOR]

The micro-resonant pressure sensor outputs frequency signals for which distortion does not take place over long-distance transmission. As the dimensions of the sensor decrease, the nonlinear coupling effects caused by the van der Waals force, electrostatic force, and air damping force should be considered. Here, based on the nonlinear dynamic equation, the amplitude-frequency characteristics near resonance and the equation on the displacement response far away from resonance are obtained. Using these equations, changes in the sensor's amplitude-frequency characteristics and the vibration amplitude far away from resonance, along with the system parameters, are investigated. The variations of the chaotic vibration characteristics of the sensor with the thickness of the resonator are studied by the numerical method. The results show that the relevant parameters of the resonator have a great influence on the primary resonance and bifurcation of the sensor. The sensor changes from periodic vibration to chaotic vibration through period-doubling bifurcation in a certain range of parameters. These results can be used to determine the measurements of the resonators to ensure sensor performance. [ABSTRACT FROM AUTHOR]

In the present manuscript, the generalized differential quadrature method (GDQM) will be employed in order to solve the free vibration problem of three-phase carbon fiber/nanotube/polymer hybrid nanocomposite conical shells, rested on a two-parameter elastic medium, regarding for the influence of the agglomeration of the carbon nanotubes (CNTs) on the dynamic responses of the shell for the first time. The equivalent material properties of the multi-scale hybrid nanocomposite will be derived according to a two-step homogenization procedure including the Eshelby-Mori-Tanaka method incorporated with the modified form of the rule of the mixture. Afterward, the strain-displacement relationships of the continuous system will be obtained using the classical shell theory for thin-walled conical shells. Extending the Hamilton's principle for the conical shell, the motion equation of the problem will be enriched. At the end, the associated boundary condition will be used in associated with the GDQ discretization for the purpose of extracting the natural frequency of the continuous system. The verification tests reveal that the presented mathematical framework is powerful enough to estimate the dynamic response of the system. The results of this study show that existence of agglomeration phenomenon can dramatically affect the dynamic behaviors of the nanocomposite structure. [ABSTRACT FROM AUTHOR]

The magnetoresistance of multi-walled carbon nanotubes is studied in the temperature range 4.2–200 K and magnetic fields up to 9 T. The magnetoresistance is negative in the whole temperature range. For small magnetic fields and low temperatures, the dependence of the relative conductivity on the magnetic field is quadratic. However, as the magnetic field increases, it becomes logarithmic, which may be described by weak localization and charge carriers' interaction models. We show that the addition to conductivity due to the charge carriers' weak localization significantly exceeds the addition due to the effect of the charge carriers' interaction. The Fermi energy and the charge carriers' interaction constant were estimated in terms of these models using the experimental data on the magnetoresistance field and temperature dependences. Also, we determined the exact form for the temperature dependence of the phase relaxation time of the charge carriers' wave function. [ABSTRACT FROM AUTHOR]

The vibration of carbon nanotubes embedded in elastic medium is a hot topic and many research findings are available. But when the medium is a fractal medium such as chips, ceramics, etc., its vibration characteristics are difficult to explain with the existing theories. So in this paper, we mainly study the nonlinear vibration of carbon nanotube embedded in a fractal medium. The fractal variational principle of the problem is successfully established, and is proved to have a strong minimum condition according to the He–Weierstrass Theorem. Then the Hamiltonian theory combined with the residual equation is implemented to find the solution of the fractal nonlinear vibration. Finally, the impacts of different fractal orders on the vibration characteristics are also presented. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes (MWNTs) exist as aggregates of highly entangled tubes due to large aspect ratios and strong Van der Waals interactions among them in their native states. In order to render them suitable for any application, MWNTs need to be separated and dispersed uniformly in a solvent preferably as individual tubes. In the present work, it is demonstrated that a double tail lipid such as 1, 2-dipalmitoyl- sn -glycero-3-phosphoethanolamine (DPPE) is capable of dispersing MWNTs in ethanol. Ultra-stable suspensions were obtained by optimizing two key parameters: DPPE to MWNT weight ratio (ε) and MWNT concentration (c). Stability of the suspensions increased with the increasing ε value up to an optimum point (ε = 1.8) and then decreased drastically beyond that. CNT dispersions with ε = 1.8 were extremely stable (with a Zeta potential of 108.26 ± 2.15 mV) and could be retained in suspended form up to 3 months. Effect of MWNT concentration on disaggregation was very significant and stable suspensions could be formed for MWNT concentrations only below 0.14 mg mlâˆ'1. Above this concentration, no stable dispersions could be obtained even with ε = 1.8. Compression isotherms of Langmuir monolayers of the DPPE functionalized MWNTs spread at the air water interface were highly repeatable, suggesting that the MWNTs in dispersion were present as separate tubes coated with phospholipids. SEM micrographs of the Langmuirâ€"Blodgett (LB) films, deposited at high surface pressures on silicon wafers, show that MWNTs remain as single nanotubes with no signs of reaggregation. TEM micrographs of MWNT suspensions indicated random adsorption of DPPE on MWNTs. Our work makes it possible to explore potential applications of LB films of MWNTs (stabilized by DPPE) in the development of conducting thin films for sensor applications or as supports to immobilize catalysts for heterogenous reactions. [ABSTRACT FROM AUTHOR]

At the macroscopic scale, the friction force (f) is found to increase with the normal load (N), according to the classic law of Da Vinci–Amontons, namely, f = µN, with a positive definite friction coefficient (μ). Here, first‐principles calculations are employed to predict that, the static force f, measured by the corrugation in the sliding potential energy barrier, is lowered upon increasing the normal load applied on one layer of the recently discovered ferroelectric In2Se3 over another commensurate layer of In2Se3. That is, a negative differential friction coefficient μ can be realized, which thus simultaneously breaking the classic Da Vinci–Amontons law. Such a striking and counterintuitive observation can be rationalized by the delicate interplay of the interfacial van der Waals repulsive interactions and the electrostatic energy reduction due to the enhancement of the intralayer SeIn ionic bonding via charge redistribution under load. The present findings are expected to play an instrumental role in design of high‐performance solid lubricants and mechanical‐electronic nanodevices. [ABSTRACT FROM AUTHOR]

Studying two‐dimensional (2D) van der Waals (vdW) moiré superlattices and their interlayer interactions have received surging attention after recent discoveries of many new phases of matter that are highly tunable. Different atomistic registry between layers forming the inner and outer nanotubes can also form one‐dimensional (1D) vdW moiré superlattices. In this review, experimental observations and theoretical perspectives related to interlayer interactions in 1D vdW moiré superlattices are summarized. The discussion focuses on double‐walled carbon nanotubes (DWNTs), a model 1D vdW moiré system, and the authors highlight the new optical features emerging from the non‐trivial strong interlayer coupling effect and the unique physics in 1D DWNTs. Future directions and questions in probing the intriguing physical phenomena in 1D vdW moiré superlattices such as, correlated physics in different 1D moiré systems beyond DWNTs are proposed and discussed. [ABSTRACT FROM AUTHOR]

Fiber-type solid-state supercapacitors are being widely investigated as stable power supply for next-generation wearable and flexible electronics. Integrating both high charge storage capability and superior mechanical properties into one fiber is crucial to realize fiber-type solid-state supercapacitors. In this study, we design a "jeweled necklace"-like hybrid composite fiber comprising double-walled carbon nanotube yarn and metal-organic frameworks (MOFs). Subsequent heat treatment transforms MOFs into MOF-derived carbon (MDC), thereby maximizing energy storage capability while retaining the superior mechanical properties. The hybrid fibers with tunable properties, including thickness and MDC loading amount, exhibit a high energy density of 7.54 milliwatt-hour per cubic centimeter at a power density of 190.94 milliwatt per cubic centimeter. The mechanical robustness of the hybrid fibers allows them to operate under various mechanical deformation conditions. Furthermore, it is demonstrated that the resulting superstrong fiber delivers sufficient power to switch on light-emitting diodes by itself while suspending 10-kilogram weight. [ABSTRACT FROM AUTHOR]

Using a molecular-dynamics model with a reduced number of degrees of freedom, the natural frequencies of bending vibrations of carbon nanotubes (CNTs) of various diameters are calculated under plane strain conditions. It is shown that the theory of thin cylindrical shells provides high accuracy in estimating the frequencies of low-amplitude natural vibrations even for relatively small CNT diameters. It is shown that, with an increase in amplitude, the frequency of natural vibrations decreases, which is consistent with the data available in the literature. The results obtained are necessary for the design of terahertz resonators based on CNTs and high-precision mass and force nanosensors based on the effect of electromechanical coupling that CNTs exhibit. [ABSTRACT FROM AUTHOR]

Strained aromatic macrocycles based on cycloparaphenylenes (CPPs) are the shortest repeating units of armchair single-walled carbon nanotubes. Since the development of several new synthetic methodologies for accessing these structures, their properties have been extensively studied. Besides the fundamental interest in these novel molecular scaffolds, their application in the field of materials science is an ongoing topic of research. Most of the reported CPP-type macrocycles display strong binding toward fullerenes, due to the perfect match between the convex and concave π-surfaces of fullerenes and CPPs, respectively. Highly functionalized CPP derivatives capable of supramolecular binding with other molecules are rarely reported. The synthesis of highly functionalized [ n ]cyclo-2,7-pyrenylenes leads to CPP-type macrocycles with a defined cavity capable of binding non-fullerene guests with high association constants. [ABSTRACT FROM AUTHOR]

Interference effects in finite sections of one-dimensional moiré crystals are investigated using a Landauer-Büttiker formalism within the tight-binding approximation. We explain interlayer transport in double-wall carbon nanotubes and design a predictive model. Wave function interference is visible at the mesoscale: in the strong coupling regime, as a periodic modulation of quantum conductance and emergent localized states; in the localized-insulating regime, as a suppression of interlayer transport, and oscillations of the density of states. These results could be exploited to design quantum electronic devices. [Display omitted] [ABSTRACT FROM AUTHOR]

We investigated the influence of different orientations of Stone–Wales defects on the structural and electronic properties of DWBNNT. Upon introducing Stone–Wales defects to the nanotube surface, homo-nuclear B–B and N–N bonds were generated. These bonds are unfavorably in withdrawer–withdrawer and donor–donor contacts. Our result indicates that the formation energy difference for all cases of Stone–Wales defects lies generally in the different rolling-up strain of these three defects. This energy difference originated for the two concentric tubes in the DWBNNT. The calculated B–B and N–N bond lengths for type I Stone–Wales defects (inner and outer walls) longer than those for Stone–Wales defect-type II and Stone–Wales defects-type III. Upon introducing different orientations of Stone–Wales defects, protrude was observed when Stone–Wales defects created in the outer tube. However, intrude was observed when Stone–Wales were generated in the inner tube of DWBNNT. In either case, the pyramidalization angle was least for type I Stone–Wales defects. While calculating the band gap for all cases, a slight reduction in the band gap were observed compared to pristine double-walled boron nitride nanotubes. [ABSTRACT FROM AUTHOR]

The interaction between drugs and single-walled carbon nanotubes is proving to be of fundamental interest for drug system of delivery and nano-bio-sensing. In this study, the interaction of pristine CNT with carbazochrome, an anti-hemorrhagic or hemostatic agent, was investigated with M06-2X functional and 6-31G* basis set. All probable positions of related adsorption for these kind drugs were thought-out to find out which one is energetically suitable. Based on the achieved data, the stronger interactions appeared the oxygen atom of C = O group and nitrogen atom of imine groups. The topology analysis of QTAIM (quantum theory of atoms in a molecule) method was accomplished to understand the properties of interactions between the CNT and carbazochrome. Frontier molecular orbital energies of all systems, global index including stiffness, softness, chemical Gibbs energies, and electrophilicity parameters, as well as some other important physical data such as dipole moment, polarizability, anisotropy polarisibility, and hyperpolaribility were calculated, evaluated, and then compared together. The essence of the formed bonding model progress along the reaction roots was further validated using electron localization function (ELF) calculations. The highest values of adsorption energies were determined in the range of 18.24 up to 22.12 kcal mol−1 for these kind systems. The acceptable recovery time of 849 s was obtained for the desorption of carbazochrome from the CNT surface under UV-light. The final results exhibit that carbazochrome can serve as a promising carrier and also as sensitive sensors in any kind of practical application. [ABSTRACT FROM AUTHOR]

Hybrid hydrogel systems of functionalized multi‐walled carbon nanotubes and zwitterionic sulfobetaine copolymer of thermo‐responsible poly(N‐isopropylacrylamide) (PNIPAM) are synthesized and testified against different existing diffusion kinetic models in neutral, acidic, and basic environments. Evaluating these hybrid hydrogels' swelling patterns at different pH indicates that changing pH can tailor the diffusion mechanism without affecting its diffusion kinetics. Interestingly, it is also revealed that diffusion kinetics and diffusion mechanisms are two distinct phenomena and can be viewed separately for supramolecular hybrid hydrogel systems. Elovich kinetic model best describes the swelling kinetics of only PNIPAM hydrogel. Diffusion kinetics of hybrid hydrogel of PNIPAM and CNTs or PNIPAM, zwitterion, and CNTs follow pseudo‐first‐order, while pseudo‐second‐order‐kinetics best describe hydrogels with only zwitterions. Evaluation of diffusion mechanism at different pH reveals that hydrogels with only zwitterions follow anomalous non‐Fickian diffusion, whereas only CNTs follow normal Fickian diffusion irrespective of pH; combining both systems leads to a dual‐stage diffusion mechanism at pH 2, which in turn reduces as the pH increases. These observations suggest that synergistic effects of supramolecular interactions can provide a novel property profile to hybrid hydrogels, requiring attention while designing such a system where diffusion is a decisive parameter. [ABSTRACT FROM AUTHOR]

Purpose: In this research work, the nonlinear damped transient response of functionally graded carbon nanotube (CNT)-reinforced magneto-electro-elastic (FG-CNTMEE) shells are investigated using finite element methods. Method: The controlled response is obtained through active constrained layer damping (ACLD) treatment composed of a 1–3 piezoelectric (PZC) patch and the viscoelastic layer. The FG-CNTMEE shell subjected to different forms of load cases including mechanical and electro-magnetic loads are considered for evaluation. In addition, the influence of open circuit and closed circuit electro-magnetic boundary conditions on the damped transient response of the FG-CNTMEE shell is investigated for the first time in the literature. The equations of motion are derived using the principle of virtual work. The solutions are obtained through the condensation approach and the direct-iterative method. Results: Several numerical examples are presented to assess the influence of parameters such as shell geometries, CNT distribution pattern, CNT volume fraction, and boundary conditions. Special attention has been paid to understand the effect of coupling fields on the damped response of the FG-CNTMEE shell. [ABSTRACT FROM AUTHOR]

Purpose: It is intended to investigate the modes of vibration of single-walled and double-walled carbon nanotubes with an attached mass, to gain knowledge useful for the application of CNTs for mass and cell detection. A related goal is the development and validation of a shell model that can be applied for the former purpose. Methods: A p-version finite element method model based on Sanders–Koiter's shell theory and considering the small size effects by employing Eringen's non-local theory is employed. Van der Waals forces are included in the interlayer stiffness of DWCNTs. Concentrated attached masses are included through their inertia, which is affected by non-local terms. The convergence and validity of the models are tested by comparisons to Molecular Dynamics simulations and atomistic–continuum hybrid finite element analysis. Results: Studies are conducted on the influence of the non-local parameter, which is calibrated for natural frequencies of different order and CNTs of different lengths. Critical values of length for which the non-local theory remains relevant depend upon the equivalent material and geometric properties employed, but more important is the verification that the non-local shell theory can be used to improve the accuracy of continuum CNT models. The dynamic behaviour of bridged SWCNTs and DWCNTs is studied, examining their applicability in mass detection devices. Conclusion: The large influence a localised mass has on the mode shapes of vibration is illustrated. Sensitivity increases more significantly in lower length carbon nanotubes. Furthermore, it is found that SWCNTs have a higher sensitivity to attached concentrated masses than DWCNTs with similar diameter, making the former more appealing candidates for mass detection nanodevices. [ABSTRACT FROM AUTHOR]

Diamond-like carbon (DLC) film has been developed as an extremely effective lubricant to reduce energy dissipation; however, most films should undergo running-in to achieve a super-low friction state. In this study, the running-in behaviors of an H-DLC/Al2O3 pair were investigated through a controllable single-asperity contact study using an atomic force microscope. This study presents direct evidence that illustrates the role of transfer layer formation and oxide layer removal in the friction reduction during running-in. After 200 sliding cycles, a thin transfer layer was formed on the Al2O3 tip. Compared with a clean tip, this modified tip showed a significantly lower adhesion force and friction force on the original H-DLC film, which confirmed the contribution of the transfer layer formation in the friction reduction during running-in. It was also found that the friction coefficient of the H-DLC/Al2O3 pair decreased linearly as the oxygen concentration of the H-DLC substrate surface decreased. This phenomenon can be explained by a change in the contact surface from an oxygen termination with strong hydrogen bond interactions to a hydrogen termination with weak van der Waals interactions. These results provide new insights that quantitatively reveal the running-in mechanism at the nanoscale, which may help with the design optimization of DLC films for different environmental applications. [ABSTRACT FROM AUTHOR]

This study focuses on mechanical characterization of carbon fiber reinforced polymer (CFRP) laminates reinforced with non-treated and treated multiwalled carbon nanotubes (CNTs) using nitric acid. The CNTs were treated using nitric acid to obtain carboxylic functional group. The epoxy resins are mixed with 0.3%wt of multiwalled CNTs at a constant mixing speed of 2000 rpm and mixing times varied from 24 to 96 h. Laminates reinforced with treated multiwalled CNTs show an increase in the flexural strength by 17.4 and 15.3% at mixing times of 24 and 96 h as compared to control laminates. The test results indicated that laminates reinforced with treated multiwalled CNTs have improved interlaminar shear failure stress which is 14 and 7% higher at mixing times of 24 and 96 h as compared to control specimen. Improvement in behavior was achieved for functionalized CNTs based laminates which prevents agglomeration. Longer mixing time (96 h) is not beneficial for enhancing the mechanical properties due to the break-up of small aggregates by overcoming the effect of van der Waals forces. [ABSTRACT FROM AUTHOR]

Electromechanical response (EMR) of carbon nanotube (CNT) fiber is a collective contraction behavior of CNT network, as a consequence of the densification process of assembly structure under electromagnetic force, Ampère force. Load drop at first electric stimulus in EMR test is the manifestation of modulus loss that is opposite to the densification process. The contradiction between modulus loss and collective contraction behavior provides a novel perspective to investigate the microstructure change in EMR. Herein, a structure evolution mechanism was proposed to explain the modulus loss in EMR. Distance between CNTs in some nodes increased under the Ampère force from adjacent CNTs, and the increasing distance weakened the bond effect of van der Waals force, resulting in the appearance of load drop. A mathematical model was applied to fit the experimental stress-strain curves of CNT fiber with different current intensities, and the variation of relevant parameters supported the structure evolution mechanism. Structure densification process driven by Ampère force was also testified as the working principle of EMR by analyzing the thermal expansion in EMR. The relationship between Ampère force, external load, van der Waals force and modulus loss was also discussed. [Display omitted] • A structure evolution mechanism for electromechanical response of CNT fiber. • Ampère force weakening Van der Waals force between CNTs in the nodes. • Mathematical simulation method was applied to fit stress-strain curve of CNT fiber. • Working principle of electromechanical response was proven, Ampère force driving. [ABSTRACT FROM AUTHOR]

Even though ultrasonication is considered to be an effective method to disperse carbon nanotubes (CNTs), its devastating effects on the nanotubes are often neglected. Here, even mild ultrasonication is found to rapidly extract the inner single-wall CNTs (SWCNTs) from the outer shells of the double-wall CNTs (DWCNTs). As-synthesized DWCNTs are gently solubilized in a surfactant solution, strictly avoiding any ultrasonication, followed by two consecutive density gradient ultracentrifugation (DGU) steps to obtain a purified colloidal solution of isolated DWCNTs. The latter is carefully selected based on in situ resonant Raman (RRS) and fluorescence (PL) spectroscopy, measured as a function of depth directly in the ultracentrifuge tube after DGU. These purified DWCNTs are ultrasonicated in successive time steps while intermittently probing the sample via RRS and PL spectroscopy. These results unravel the very fast increasing, yet saturating extraction mechanism that leads to the formation of fluorescing SWCNTs. A statistical high-resolution transmission electron microscopy study confirms the drastic increase in SWCNTs after ultrasonication, and evidences that ultrasonication forms SWCNTs from both the inner and outer shells of the DWCNTs. This study demonstrates how easily ultrasonication extracts SWCNTs from individually solubilized DWCNTs, unavoidably complicating any further spectroscopic studies on DWCNTs severely. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, "peristaltic transport of hybrid nanofluid" inside a rectangular duct is examined. Water (base fluid) is used with two types of nanoparticles, namely, single-walled carbon nanotube (SWCNT) and multi-walled carbon nanotube (MWCNT). The viscous dissipation effect comes out as the prime heat generation source as compared to the conduction of molecules. After using some suitable dimensionless quantities, we obtained the nonlinear partial differential equations in a coupled form which are then solved exactly by the Eigenfunction expansion method. Velocity distribution, pressure gradient, and pressure rise phenomena are also discussed graphically through effective physical parameters. The heat transfer rate is high for the phase flow (single-walled carbon nanotube/water) model as compared to the hybrid (single-walled carbon nanotube + multi-walled carbon nanotube/water) model due to the enhanced thermal conductivity of the hybrid model. [ABSTRACT FROM AUTHOR]

In this study, interactions of multi-walled carbon nanotubes (MWCNTs) with benzoic acid and 2-halogeno (F-, Cl- and Br-) derivatives were investigated. In addition, these compounds were determined to be cytotoxic on Primary Peripheral Blood Mononuclear cells. Adsorption percentages of MWCNTs exposed to these acids at the same concentration for 24 hours were calculated. Raman spectroscopy, Fourier Transform Infrared Spectrocsopy (FT-IR) and Scanning Electron Microscope (SEM) techniques were used to determine the chemical and physical changes caused by acid species on the structure of MWCNTs. As a result of the investigations, it was determined that 2-bromobenzoic acid (BrBA) was adsorbed most favorably by the structure. The structure adsorbed the benzoic acid derivatives better than benzoic acid (BA). The least defect occurred in the sample subjected to BrBA. It was found that there was no correlation between absorption rates and defect occurrences in the structure. SEM results indicate aggregation, tube curl, and filling in inter-tube spaces in samples where absorption is intense. In FT-IR spectra of all structures obtained, the characteristic vibration band related to MWCNTs, and C=O stretching vibration band of the benzoic acid and its derivatives were observed around 1450 and 1680 cm-1, respectively. [ABSTRACT FROM AUTHOR]

The present article deals with the vibration and damping characteristics of functionally graded carbon nanotubes reinforced hybrid composite skewed shell structure in different hygrothermal conditions. Carbon nanotube reinforced polymer as a matrix phase and carbon fibre as a reinforcing phase are used, and carbon fibre is graded with uniform distribution along the thickness direction for the shell panel according to the power law distribution. The Mori–Tanaka scheme and strength of materials are used to determine the mechanical properties of such functionally graded carbon nanotubes reinforced hybrid composite materials. Finite element modelling has been done by considering an eight-noded shell element with the transverse shear effect according to Mindlin's hypothesis, and an oblique coordinate system is used for the functionally graded carbon nanotubes reinforced hybrid composite skewed shell structures. Damping is incorporated into such carbon nanotube–based hybrid skewed shell structure based on the Rayleigh damping model. A MATLAB-based in-house computer code has been developed for the proposed formulation and verified with published research work before using for the present dynamic analysis of functionally graded carbon nanotubes reinforced hybrid composite skewed shell structure under hygrothermal conditions. The effect of the carbon nanotube, carbon fibre, material distribution as per power law index and hygrothermal conditions on the damping behaviour of such functionally graded carbon nanotubes reinforced hybrid composite skewed shell structures have been studied. Furthermore, parametric studies are carried out for the first resonant frequency, absolute amplitude, settling time and carbon nanotube impact on the vibrational behaviour of different functionally graded carbon nanotubes reinforced hybrid composite skewed shell structures under different hygrothermal conditions. [ABSTRACT FROM AUTHOR]