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Numerous scientific and technological developments in wastewater treatment procedures are brought on by the shortage of clean water supplies. Heavy metals' recalcitrance in wastewater has been shown to be a difficult issue. Further, drinking water quality must be at its highest for human health to be at its best; nevertheless, a number of human activities are continuously degrading it, which has an effect on human health either directly or indirectly. Because heavy metals are the primary causes of many chronic illnesses and have a tendency to bio accumulate, they are giving rise to a lot of worries. Technologies from all over the world are being developed to address the demand for clean drinking water. The objective of the current study is to raise awareness of the need to remove dangerous dense metals from various types of wastewater and the application of modified graphene nanocomposite for their adsorption-based removal. Graphene-based nanocomposite materials have been picked for this application due to their large surface area, superior mechanical strength, and reactivity towards polar and nonpolar contaminants for the electrostatic emission of the heavy metal ions arsenic (As), chromium (Cr), copper (Cu), and lead (Pb). [ABSTRACT FROM AUTHOR]

Two different types of graphene materials were used as functional nanofillers for the mechanical and tribological improvement of silicon carbide/graphene nanocomposites. On the one hand is thermally reduced graphite oxide (TRGO) reduced at three different temperatures, and on the other hand is graphene made of three different organic precursors, which were directly coated on silicon carbide (SiC) platelets (GSiC). Additionally, benchmark materials were also used as carbon fillers. The SiC/graphene nanocomposites with 2 wt% filler content were manufactured by pressureless sintering (PLS). Some composites were produced with higher graphene contents of 4% and 8% and sintered by spark plasma sintering (SPS). Microstructural analyses were conducted using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Underwater lubrication, the SP sintered TRGO and GSiC materials with high graphene content have shown the most promising tribological performance. Furthermore, the reduced size of the homogeneously distributed nanoparticles promotes the formation of surface states, which improve the friction and wear properties. [ABSTRACT FROM AUTHOR]

In this study, the electrocatalytic behavior of tin sulfide doped with various metallic elements (copper, cobalt, nickel, and iron) for the oxygen reduction reaction was investigated. Our findings reveal cobalt as the most effective dopant in enhancing ORR efficiency. The graphene nanosheets were introduced to form a G/Co-SnS 2 nanocomposite, which significantly improved ORR performance, surpassing Pt/C in current density. Our findings underscore the positive impact of chemical doping and the synergistic effect of SnS 2 with graphene nanosheets, improving the onset potential and facilitating the ORR. Through comprehensive characterization including XRD, XPS, FESEM, and BET analysis, the structural and surface properties of the materials were evaluated. Employing the Rotating Disk Electrode technique, we observed that G/Co-SnS 2 exhibited a superior onset potential of 0.88 V vs. RHE and high current density of 6.12 mA cm−2, indicating enhanced ORR facilitation. Furthermore, Electrochemical Impedance Spectroscopy revealed lower resistance in the G/Co-SnS 2 nanocomposite compared to other samples, highlighting its enhanced durability. Additionally, G/Co-SnS 2 nanocomposite demonstrated significantly enhanced durability in comparison to the costly Pt/C catalyst, further underscoring its potential as a robust alternative for catalyzing the oxygen reduction reaction. These comprehensive characterizations provide insights into the enhanced electrocatalytic performance observed. Overall, this study highlights the promising potential of Co-doped SnS 2 in combination with graphene nanosheets for efficient oxygen reduction reactions, opening avenues for advanced electrocatalytic materials in energy applications. [Display omitted] [ABSTRACT FROM AUTHOR]

As well known, the electrochemiluminescence (ECL) of tris(2,2′-bipyridine)ruthenium(ii) (Ru(bpy)32+) heavily relies on highly positive or negative triggered voltage, prejudicing the detection toward the bio-molecules. In this work, Ru(bpy)32+ could generate enhanced and stable ECL at a low potential of 0.05 V (vs. Ag/AgCl) on graphene-PtPd hybrid, attributing to its excellent electrocatalysis from the synergistic effect between Pt and Pd. The obtained low-potential-driven ECL could be quenched by MoS2 nanoflowers. Based on the quenching effect, a sandwich "signal-off" ECL immunosensor was fabricated to sensitively detect carcinoembryonic antigen (CEA). A linear calibration curve from 1 fg mL−1 to 1 ng mL−1 was obtained along with a low detection limit of 0.54 fg mL−1 (S/N = 3) under optimal conditions. The sensor showed satisfactory specificity, stability, and reproducibility and was successfully applied to determine CEA in actual samples. The recoveries ranged from 98.80 to 100.23%, and the relative standard deviation (RSD) was lower than 5%. Above all, this work explored new materials in low-potential-driven ECL system and provided a reliable sensing strategy for clinical applications. [ABSTRACT FROM AUTHOR]

As well known, the electrochemiluminescence (ECL) of tris(2,2′-bipyridine)ruthenium(ii) (Ru(bpy)32+) heavily relies on highly positive or negative triggered voltage, prejudicing the detection toward the bio-molecules. In this work, Ru(bpy)32+ could generate enhanced and stable ECL at a low potential of 0.05 V (vs. Ag/AgCl) on graphene-PtPd hybrid, attributing to its excellent electrocatalysis from the synergistic effect between Pt and Pd. The obtained low-potential-driven ECL could be quenched by MoS2 nanoflowers. Based on the quenching effect, a sandwich "signal-off" ECL immunosensor was fabricated to sensitively detect carcinoembryonic antigen (CEA). A linear calibration curve from 1 fg mL−1 to 1 ng mL−1 was obtained along with a low detection limit of 0.54 fg mL−1 (S/N = 3) under optimal conditions. The sensor showed satisfactory specificity, stability, and reproducibility and was successfully applied to determine CEA in actual samples. The recoveries ranged from 98.80 to 100.23%, and the relative standard deviation (RSD) was lower than 5%. Above all, this work explored new materials in low-potential-driven ECL system and provided a reliable sensing strategy for clinical applications. [ABSTRACT FROM AUTHOR]

Antibiotics determination plays a major role in minimizing antimicrobial resistance starting from quality control of pharmaceutical formulations to therapeutic drug monitoring. Green modified glassy carbon electrode has been developed for determination of tedizolid phosphate; new antibiotic prodrug; in presence of its active metabolite. The graphene transducer interlayer, dispersed with PVC, improved the electrode stability and standard potential reproducibility. Graphene hydrophobicity prevented the water layer formation between the sensing layers that decreased the potential drift down to 267 μV h−1. Electrochemical impedance showed a low resistance value for graphene containing sensor due to its high electron transfer ability. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of a new class of polybutadiene polyol polyurethanes were investigated with three consecutive reactions, namely polybutadiene (PB) chain cleavage by a two-step oxidation reaction using meta-chloroperbenzoic acid (m-CPBA) and periodic acid (H5IO6) in order to prepare polybutadiene polyol precursor, continued by telechelic amine polyol synthesis by an amination reaction using diethanolamine (DEA) in the presence of sodium borohydride (NaBH4) and finally telechelic polyurethane preparation by the reaction of synthesized polyol and toluene diisocyanate (TDI). Nanocomposites were prepared through an in situ polymerization reaction by incorporation of 1–3 wt% of graphene conductive nanosheets. Successful structural elucidation of the synthesized polymeric binder and nanocomposites was investigated by using well-known methods. TGA analysis revealed slower degradation and moderate thermal stability in higher weight percent nanocomposite. SEM images and XRD patterns resulted in fine nanoparticle distribution, lack of agglomeration and approximately constant nanoparticle size. Conductometry confirmed higher electrical conductivity data for nanocomposites by increasing graphene nanosheet contents. [ABSTRACT FROM AUTHOR]

Purpose: Traditional nanocomposite production methods such as in situ polymerization, melt blending and solvent technique, have some deficits. Some of these are non-homogeneous particle distribution, setup difficulties, time-consuming and costly. On the other hand, three-dimensional printing technology is a quite popular method. Especially, Stereolithography (SLA) printing offers some benefits such as fast printing, easy setup and smooth surface specialties. Furthermore, surface modification of Graphene Oxide (GO) and its effects on polymer nanocomposites are quite important. The purpose of this study is to examine the effect of surface modification of GO nanoparticles on the mechanical properties and morphology of epoxy acrylate (BisGMA/1,6 hexane diol diacrylate) matrix nanocomposites. Design/methodology/approach: In this study, Ultraviolet (UV) curable end groups of synthesized resin were linked to functional groups of graphene oxide, which are synthesized by the Tour method, which is a kind of modified Hummer method. In addition, synthesized GO nanoparticle's surfaces were modified by 3-(methacryloyloxy) propyl trimethoxysilane. Significant weight percentages of GO were added into the epoxy acrylate resin. Different Wt.% of modified graphene oxide/acrylate resins was used to print test specimens with SLA type three-dimensional printer. Findings: Surface modification has a significant effect on tensile strength for graphene oxide nanoparticles contained composites. In addition, a specific trend was not observed for tensile test results of non-modified graphene oxide. The tendency of impact and hardness test finding were similar for both surfaces modified and non-modified nanoparticles. Finally, the distribution of particles was homogeneous. Originality/value: This paper is unique because of the inclusion of both surface modifications of graphene oxide nanoparticles and SLA production of nanocomposites with its own production of three-dimensional printer and photocurable polymer resin. [ABSTRACT FROM AUTHOR]

The size of graphene nanofillers and the ambient temperature are two important factors for the effective thermal conductivity of graphene nanocomposites. However, these two issues together are seldom considered in theoretical evaluation of the overall thermal property. By introducing the size-dependent thermal transport mechanisms (quasi-ballistic heat flow and diffusive heat transport) to the Landauer-like theory, we established a new method to calculate the in-plane size and temperature dependence of the thermal conductivity of graphene nanofillers from the nanoscale perspective, which is crucial for the overall thermal conductivity of the nanocomposites. The validity of this approach was confirmed by nonequilibrium molecular dynamics simulation. Then the filler-size- and temperature-dependent thermal conductivity of graphene nanocomposites was calculated via an effective-medium approximation based on Maxwell's far-field matching at a microscopic level. We highlight this multiscale approach with its implementation in the estimation of the overall thermal conductivity of graphene-polymer nanocomposites. The results are shown to be in close agreement with the experimental observations over the average filler size from 200 to 1000 nm and over the temperature from 300 to 360 K, respectively. This study revealed the significant effects of the graphene-filler size and the ambient temperature on the thermal conductivity of the nanocomposites. Image 1 [ABSTRACT FROM AUTHOR]

Nanocomposite materials can enhance the capabilities of water treatment processes such as photocatalysis. In this work, novel light-driven nanocatalysts were synthesized by using nickel ferrite (NiFe2O4) to nanoenable graphene oxide (GO) substrates. GO is an emerging 2D nanomaterial with high conductivity and adsorption properties. Moreover, the electric properties of GO improve photocatalytic performance by promoting charge carrier separation. Results of the characterization of the nickel ferrite nanoenabled graphene oxide (NiFe2O4@GO) nanocomposites demonstrate that homogeneous and stable photocatalysts were produced. The as-synthesized nanocatalysts enabled complete decolorization of the colored water matrix in short irradiation times of 150 min using minimal catalyst loading at 0.5 g L−1. The selective hook and destroy mechanism reduced the competitive effect of co-existing ions in solution. Furthermore, the use of specific scavengers helped to elucidate the degradation mechanisms of organic dye methylene blue by NiFe2O4@GO nanocomposites. [ABSTRACT FROM AUTHOR]

In this study, a nanoscale graphene oxide polymer composite drug delivery system was synthesized and investigated for possible oral delivery of doxorubicin. A doxorubicin-loaded nanocomposite composed of graphene oxide/poly(2-hydroxyethylmethacrylate)-g-poly(lactide)- b -polyethyleneglycol- b -poly(2-hydroxyethylmethacrylate)-g-poly(lactide) GO/(PHEMA-g-PLA)- b -PEG- b -(PHEMA-g-PLA) was synthesized via reversible addition fragmentation chain (RAFT) and ring open polymerization (ROP). The GO/(PHEMA-g-PLA)- b -PEG- b - (PHEMA-g-PLA) nanocomposites was characterized by scanning electron microscopy (FE-SEM), thermogravimetry (TG), ultraviolet-visible (UV–Vis) spectroscopy, and dynamic light scattering (DLS). Doxorubicin was successfully loaded into the nanocomposite with a small particle size of 51 nm and an encapsulation efficiency (EE) of 82% ±1.12%. The results showed that DOX was attached to the graphene surface via hydrophobic interactions and π-π stacking. DOX release took place under neutral and acidic conditions, reaching 24.7% and 41.2% respectively after 72 h. Cytotoxicity experiments on 4T1 murine breast cancer cells demonstrated the antitumor activity of the DOX@GO nanocomposite. Biocompatibility, cell uptake, DAPI staining, Annexin V/PI double staining, intracellular reactive oxygen species (ROS) assay, and scratch healing assay were measured. The DOX@graphene nanocomposite system could be promising for breast cancer therapy. [ABSTRACT FROM AUTHOR]

In the recent drug analysis arena, optimizing a green, eco-friendly, and cost-effective technique is the main target. In order to cope with green analytical chemistry principles and the trending development of miniaturized portable and handheld devices, an innovative microfabricated ion-selective electrode for the analysis of metoclopramide (MTP) was developed. The fabricated electrode adopted a two-step optimization process. The first step of optimization depended on screening different ionophores in order to enhance the sensor selectivity. Calix-4-arene showed the maximal selectivity towards MTP. The second step was utilizing a graphene nanocomposite as an ion-to-electron transducer layer between the calix-4-arene polymeric membrane and the microfabricated copper solid-contact ion-selective electrode. The graphene nanocomposite layer added more stability to electrode potential drift and short response times (10 s), probably due to the hydrophobic behavior of the graphene nanocomposite, which precludes the formation of a water layer at the Cu electrode/polymeric membrane interface. The proposed MTP sensor has been characterized according to IUPAC recommendations and the linear dynamic range estimated to be 1 × 10−6 to 1 × 10−2 M with LOD of 3 × 10−7 M. The proposed sensor has been successfully employed in the selective determination of MTP in bulk powder, pharmaceutical formulation, and biological fluid. No statistical significant difference was observed upon comparing the results with those of the official method. The Eco-score of the method was assessed using the Eco-Scale tool and was compared with that of the official method. [ABSTRACT FROM AUTHOR]

In this manuscript, RDX (Royal Demolition eXplosive) and HMX (High Melting eXplosive) were removed from water that is mainly polluted by military activities. Two different forms of magnetic graphene oxide nanocomposites, α-Fe2O3-rGO (hematite-reduced graphene oxide) and nZVI-rGO (nano zero valent iron-reduced graphene oxide) have been evaluated for decontamination of water containing these carcinogenic explosives. Comparative adsorption studies were carried out considering contact time, pH and adsorbent dosage for all the adsorbent–adsorbate systems. Batch adsorption experiments at varied concentrations of RDX and HMX were conducted. The experimental results better fit in pseudo second order model following Freundlich isotherm. Magnetic nature of both adsorbents is suitable for their easy separation from contaminated water in presence of an external magnetic field. α-Fe2O3-rGO showed higher adsorption capacities for HMX and RDX, this was supported by the physio-chemical properties of the adsorbent. Therefore, it could be potentially upscaled and used commercially for purification of water containing explosives. [ABSTRACT FROM AUTHOR]

Abstract We report the synthesis of Mn 3 O 4 nanostructures and their graphene composites following a novel, surfactant free, single-step hydrothermal method. The structural and morphological characterizations of graphene wrapped Mn 3 O 4 nano-octahedrons (Mn 3 O 4 -rGO) are carried out using powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, Field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). We study the electrochemical properties of as-prepared Mn 3 O 4 and Mn 3 O 4 -rGO composite as anodes for lithium ion batteries (LIBs). Mn 3 O 4 -rGO composite electrode showed excellent electrochemical properties when cycled against Li/Li+, with a reversible specific capacity of 474 mAh g−1 at 100 mA g−1 upon 200 cycles. Further, we investigate the kinetics behavior of these electrodes and study their capacitive contribution towards total charge storage. With a high capacitive contribution of ∼73% at 1.0 mV s−1, Mn 3 O 4 -rGO composite electrode exhibits excellent potential for their application in lithium ion battery and hybrid lithium ion capacitor devices. Graphical abstract Image 1 Highlights • One-step synthesis of Mn 3 O 4 /rGO composite with unique morphology is demonstrated. • Mn 3 O 4 /rGO composite electrode exhibits enhanced electrochemical properties. • Excellent Li-ion kinetics is shown with a capacitive nature of ∼73% at 1.0 mV s−1. • Mn 3 O 4 /rGO composite electrode shows potential as efficient anode for LIBs. [ABSTRACT FROM AUTHOR]

In order to improve the electrochemical properties of LaMnO 3 perovskite (LMO) materials for supercapacitor applications, different amount of nitrogen-doped reduced graphene oxide (N-rGO) from 25 to 75 wt % has been incorporated with LMO to form nanocomposite materials. These three-dimensional structures are assembled through electrostatic attraction of the positive charged N-rGO and the negative charged LMO. The amount of N-rGO has a significant effect on the properties of the composite materials. Microscopic investigations confirm that LMO particles are wrapped by N-rGO sheets, and with the increase of N-rGO content, the dispersion of LMO particles in graphene matrix is enhanced. Electrochemical characterizations reveal that the specific capacitance of the nanocomposites has been dramatically improved. Compared with pristine graphene and LMO, the sample with a lower amount of N-rGO (25%) exhibited the highest specific capacitance (687 Fg −1 at 5 mVs −1 ) and the longest stability (79% retention after 2000 cycle at 10 Ag −1 ) among other composite materials. The superior capacitive properties make LMO/N-rGO nanocomposites stand out as a promising candidate for supercapacitor applications. [ABSTRACT FROM AUTHOR]

A novel binary nanocomposite, ZnO/nitrogen-doped graphene (ZnO/NG), is synthesized via a facile solution method. In this prepared ZnO/NG composite, highly-crystalline ZnO nanoparticles with a size of about 10 nm are anchored uniformly on the N-doped graphene nanosheets. Electrochemical properties of the ZnO/NG composite as anode materials are systematically investigated in lithium-ion batteries. Specifically, the ZnO/NG composite can maintain the reversible specific discharge capacity at 870 mAh g−1 after 200 cycles at 100 mA g−1. Besides the enhanced electronic conductivity provided by interlaced N-doped graphene nanosheets, the excellent lithium storage properties of the ZnO/NG composite can be due to nanosized structure of ZnO particles, shortening the Li+ diffusion distance, increasing reaction sites, and buffering the ZnO volume change during the charge/discharge process. [ABSTRACT FROM AUTHOR]

This paper deals with the thermal buckling and postbuckling of functionally graded multilayer nanocomposite plates reinforced with a low content of graphene platelets (GPLs). It is assumed that GPL reinforcements are randomly oriented and uniformly dispersed in each individual GPL-reinforced composite (GPLRC) layer but the concentration follows a layer-wise variation across the plate thickness. The modified Halpin-Tsai micromechanics model that takes into account the GPL geometry effect is adopted to estimate the effective Young's modulus of GPLRC layers. Within the framework of the first-order shear deformation theory, the nonlinear governing equations are derived by applying the principle of virtual displacements and then solved by using a differential quadrature-based iteration technique. Parametric studies are conducted to examine the influences of GPL distribution pattern, concentration and geometry, as well as in-plane force on the thermal buckling and postbuckling behaviours. Our results show that distributing more GPLs near the surface layers is capable of reinforcing the thermal buckling and postbuckling performances of GPLRC plates. Whether the thermal buckling and postbuckling resistance increases or decreases with the increases in GPL weight fraction, aspect ratio and width-to-thickness ratio is highly dependent on the GPL distribution pattern. [ABSTRACT FROM AUTHOR]

Beta-cyclodextrin capped Graphene-magnetite (G-Fe 3 O 4 -BCD) nanocomposite was synthesized by ethylenediamine conjugation and used as an adsorbent for selective removal of Bisphenol-A (BPA) in water. Characterization of nanocomposite revealed BCD conjugated to Fe 3 O 4 nanoparticles (30–40 nm) embedded on graphene. Adsorption process followed Langmuir model and pseudo second order kinetics with an adsorption capacity of 59.6 mg/g. It was found to be highly favourable physisorption and endothermic process as indicated by ΔG ° (−3.36 kJ/mol) and ΔH ° (2.08 kJ/mol) values at ambient temperatures. The nanocomposite was highly specific towards BPA compared to its analogs, largely driven by host-guest interaction between BCD and BPA. Nanocomposite had a high magnetization of 97 emu/g with superparamagnetic property at room temperature which helps in faster separation using an external magnetic field. Nanocomposite can be regenerated with methanol and can be reused without much loss in adsorption efficiency (<10%) after 6 cycles. It has huge potential and application in selective adsorption of target molecules. [ABSTRACT FROM AUTHOR]

This paper presents the axisymmetric thermal postbuckling analysis of functionally graded graphene platelets-reinforced composite (FG-GPLRC) annular plates with various geometric imperfections within the framework of first-order shear deformation theory and von Kármán geometric nonlinearity. An imperfection model composed of trigonometric and hyperbolic functions is used to simulate possible imperfections with different shapes, amplitudes and locations. The 3D Halpin–Tsai model is employed to estimate the effective modulus of graphene nanocomposites. Nonlinear governing equations are derived by the variational principle and are then solved by the generalized differential quadrature method combined with the modified Newton–Raphson iteration. Parametric studies are conducted to highlight the influences of imperfection amplitude, localization degree, location and half-wave number on the thermal postbuckling behaviour of FG-GPLRC annular plates. It is found that the thermal postbuckling resistance is reduced due to the existence of geometric imperfections, and this effect become more/less significant as the imperfection amplitude/half-wave number increases. • Thermal postbuckling of FG-GPLRC annular plates with geometric imperfections is investigated for the first time. • The 3D Halpin–Tsai model is introduced to evaluate the elastic modulus of 3D-random graphene nanocomposites. • Thermal postbuckling resistance is more weakened by the global imperfections than the localized ones. • Thermal postbuckling behaviour is less sensitive to the imperfections with a smaller amplitude or more half-waves. [ABSTRACT FROM AUTHOR]

Nitrogen-doped functional graphene nanocomposites (GO-MRF-x) for electrode materials in a capacitive deionization (CDI) application were conveniently prepared through a sol-gel polycondensation reaction catalyzed by NaCO under ambient pressure drying. The materials showed high surface functionalization (N and O groups) which were confirmed by X-ray photoelectron spectroscopy (XPS). The molar ratio of melamine with resorcinol had a marked effect on the specific surface area and porosity of the nanocomposites. The characterization results showed that with the specific surface area of 387 m g and N content of 7.26 wt%, laminated GO-MRF-0.8 material exhibited a good performance with high specific capacitance (222 F g), low charge-transfer resistance (0.10 Ω), and electrosorption capacity (16.72 mg g). Furthermore, the electrosorption isotherms were studied, and it was found that the ion electrosorption behavior of NaCl on GO-MRF-0 followed multilayer adsorption, whereas GO-MRF-0.8 exhibited a change from monolayer to multilayer. [ABSTRACT FROM AUTHOR]

Carbon nanomaterials such as graphene and its derivatives based membranes in real applications are still far from reality due to their hydrophobic nature and limitations in their fabrication process. Here, we have devised a simple and feasible fabrication method to bring the high end nanocarbon based material to real downstream applications. In order to achieve this objective, the wettability of graphene was initially increased to an ultra-wetting level by incorporating amine and carboxyl functionality onto the graphene. The amine and carboxylated graphene is then covalently attached to a polymer matrix to fabricate a water filtration membrane. The characterization of the modified supported graphene-based membrane indicates that significantly higher hydrophilicity than previously expected is achieved, with the water contact angle reduced to zero. The ultra-wetting graphene increases the water permeability of the membrane by 126% without any changes in the selectivity. Based on our findings, we conclude that the ultra-wetting graphene will be an ideal material for new generation water filtration membranes. [ABSTRACT FROM AUTHOR]

A novel paper-based dot immune-graphene-gold filtration assay (DIGGFA) for the detection of breast cancer cells was developed based on the photo-thermal effect of graphene oxide (GO)-Au nanocomposite. Anti-EpCAM antibody which specific to the MCF-7 cell surface antigen, was immobilized on the nitrocellulose paper. The GO-Au-anti-EpCAM composite would interact with the MCF-7 cells captured on the nitrocellulose paper. After the test zone was irradiated by a laser, GO-Au nanocomposite could generate heat, temperature contrast was recorded and positive correlated with the cell number. Standard curve was prepared according to the temperature contrast and the cell number. Under optimal conditions, this method could detect a minimum of 600 MCF-7 cells with a near infrared laser and an infrared temperature gun within 15 min. This simple and rapid method could be applied to the clinical diagnosis in hospitals. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, a novel ionic polymer actuator employing a graphene nanocomposite (GN) as its electrodes was fabricated. By a conventional solvent mixing of a graphene nanopowder and polystyrene, a GN solution was prepared. The solution was then utilized in a dip coating process of an ionic polymer membrane, forming a thin liquid GN layer on the surfaces of the ionic polymer membrane. After removing the solvent from the coated film, the solidified conducting GN layer could be obtained, which was used as the electrodes in the ionic polymer actuator. An electrical property of the GN layer formed by the present method was characterized, confirming the possibility of the present GN in the actuator applications. Simple and reverse bending motions of the fabricated actuator were also investigated, verifying the usefulness of both the GN layer and the present simple fabrication method. [Copyright &y& Elsevier]

The large-amplitude free vibration behaviors of rotating pre-twisted functionally graded (FG) nanocomposite multilayered blade reinforced with graphene platelets (GPLs) in a thermal environment is comprehensively investigated in the paper. It is assumed that the GPLs volume fraction varies gradually from layer to layer across the blade thickness direction but remains constant in each individual GPLs-reinforced composite (GPLRC) layer. The modified Halpin-Tsai micromechanical model is exploited to obtain the effective Young's modulus of each GPLRC layer while Poisson's ratio, mass density, and thermal expansion coefficient are determined via Voigt's rule. The nonlinear dynamic model of pre-twisted GPLRC blades at moderate rotational speed in a thermal environment is derived based on the first-order shear deformation theory (FSDT) combined with the improved version of the Novozhilov nonlinear shell theory. The nonlinear vibration characteristics of FG GPLRC blades are obtained by applying the element-free improved moving least-square Ritz (IMLS-Ritz) method in conjunction with a direct iterative scheme. Validation of obtained results is performed in detail and show effectiveness of used numerical approach and fast convergence of obtained results to exact values. The impacts of rotating speed, pre-twisted angle, presetting angle, and aspect ratio on nonlinear to linear frequency ratio of GPLRC blades are studied with emphasis on temperature rise and nano reinforcement parameters. Finally, new insights into dynamics of nanocomposite rotating blades with conclusions are presented in detail. [ABSTRACT FROM AUTHOR]

The sulfur on the sulfur-assisted reduced graphene oxide (SrGO) surface provides the origin of poly(phenylene sulfide) PPS-grafting via SNAr mechanism. In-situ polymerization from sulfur on SrGO afforded surface modification of SrGO, resulting in enhanced dispersibility in PPS. The tensile strength, electrical and thermal conductivities, and flame retardancy of PPS-coated SrGO were efficiently enhanced using highly concentrated SrGO and masterbatch (MB) for industrial purposes. Three-dimensional X-ray microtomography scanning revealed that diluting MB in the PPS resin afforded finely distributed SrGO across the PPS resin, compared to the aggregated state of graphene oxide. For the samples after dilution, the thermal conductivity and flame retardancy of PPS/SrGO are preserved and typically enhanced by up to 20%. The proposed PPS/SrGO MB shows potential application as an additive for reinforced PPS due to the ease of addition during the extrusion process. [ABSTRACT FROM AUTHOR]

An eco-friendly procedure for the preparation of high-quality graphene incorporated iron oxide nanocomposite is reported, which is effectively used for the electrochemical determination of acetaminophen drug. The graphene dispersion is prepared by the exfoliation of graphite in a green solvent (water/ethanol 90:10 vol%/vol%) in the presence of a non-ionic surfactant for better yields. Material characterization studies reveal the lower deficiency nature of graphene sheets as well as the exclusive formation of the hematite phase of iron(III) oxide in the nanocomposite. Electrocatalytic sensing of paracetamol is carried out using cyclic voltammetric and differential pulse voltammetric measurements. A high linear concentration range of 0.3 μM–1800 μM paracetamol is observed over the hematite/graphene nanocomposite modified glassy carbon electrode. The nanocomposite is found to be highly selective in the detection of paracetamol with the presence of dopamine and other common contaminants interfered in human sample analysis. The analytical utility of the hematite/graphene-modified electrode in the estimation of the real tablet sample is also investigated. Electrochemical sensing of paracetamol is performed in a wide linear range using α-Fe 2 O 3 dispersed high quality graphene sheet modified electrode. [Display omitted] • A green one-pot low cost new synthetic route for α-Fe 2 O 3 /graphene nanocomposite in alcoholic aqueous media. • Graphene dispersion is obtained in ethanol/water mixture with the assistance of a non-ionic surfactant. • Less defective graphene sheets are generated that are highly beneficial in electrochemical applications. • The composite is effectively used as a sensitive and selective sensing platform for paracetamol. • Wide linear range, repeatability, stability and reproducibility are the prime features of the α-Fe 2 O 3 /graphene-GCE. [ABSTRACT FROM AUTHOR]

In this paper, a meshless method has been developed to analyze stresses and deflections in an advanced smart lightweight sandwich plate (ASLSP) subjected to thermo-electro-mechanical loads. In ASLSP, a passive sandwich plate consisting of a lightweight porous core and two graphene nanocomposite layers is integrated between two active piezoceramic faces. Moreover, functionally graded profiles have been considered for the dispersions of porosity and graphene in their corresponding layers. In the meshless method, MLS shape functions has been utilized, and essential boundary conditions are implemented using transformation approach. A version of Halpin-Tsai equations capable of capturing nanoscale effects of randomly oriented graphene is adopted to approximate the temperature dependent mechanical properties of graphene nanocomposite layers. The highly coupled governing equations are extracted by minimizing total energy function obtained from the estimation of displacement domain with Reddy's third order plate theory (called TSDT). The influences of different aspects of ASLSP including loading, graphene content, porosity and geometric details have been studied on thermo-electro-mechanical stresses and deflections. It is observed that both graphene content and dispersion profile have considerable influence on ASLSP's deflections. Moreover, embedding pores in core layer offers a significant reduction in structural weight and a considerable stability in structural bending stiffness. [ABSTRACT FROM AUTHOR]

The effect of failure at the filler-matrix interface on the tensile stress-strain response of graphene-based polymer nanocomposites is studied using micro-scale finite element (FE) modeling. Interfacial failure can occur in the form of debonding or slip. Based on previous studies (Jiang et al., 2014 ; Anagnostopoulos et al., 2015 ; Li et al., 2017), interfacial slip, which causes friction-like interaction between the filler and matrix, is identified as the major failure mechanism that affects the nanocomposite response. By establishing single-filler models in ABAQUS, it is demonstrated that interfacial slip affects the stress-strain response of the nanocomposite in two ways. Firstly, it limits the load that can be transferred to the filler. Secondly, it causes a shear displacement discontinuity across the interface, and this generates additional strain over and above those of the matrix and filler; this reduces the level of stress enhancement in the nanocomposite that the incorporation of fillers contribute, and under certain conditions, even weaken the nanocomposite. Models with fully aligned and randomly oriented fillers are also established to examine the influence of parameters such as filler orientation, interfacial slip strength, and filler aspect ratio, on the tensile response of the nanocomposite. The model developed is employed to describe the tensile response of an actual polyvinyl alcohol (PVA)- graphene oxide (GO) nanocomposite, and good correlation with experiments is observed. • Study of uniaxial tensile stress-strain response of graphene-based polymer nanocomposites through establishment of FE RVE models with fully aligned and randomly oriented fillers • Identification of friction-like slip between the matrix and the fillers as the dominant interfacial failure mechanism, resulting in a significant effect on the stress-bearing capacity of the nanocomposite • Examination of how interfacial slip limits the stress transferred to the filler and generates additional strain which would be absent with perfect bonding • Verification of the FE model by data from experimental tests on a PVA-graphene oxide nanocomposite [ABSTRACT FROM AUTHOR]

• Investigation into uniaxial tensile response of a PVA-graphene oxide nanocomposite over a strain rate range of 0.003–1200/s. • Identification and analysis of interfacial slip between polymer matrix and filler as a dominant mechanism influencing the stress–strain response. • Simulation of the mechanical response of the nanocomposite using a modified Mori-Tanaka approach which accommodates the effect of interfacial slip. • Analysis of the rate sensitivity of the nanocomposite by examination of the initial elastic stiffness and stress level at a strain of 0.1, as a function of strain rate. The dynamic stress–strain response of a polyvinyl alcohol (PVA) – graphene oxide (GO) nanocomposite is examined through tensile testing over a strain rate range of 0.003–1200/s, as well as via theoretical microscale modeling. PVA-GO samples with various GO content were prepared and subjected to uniaxial tension using a universal testing machine and a split Hopkinson tension bar arrangement. In previous studies by the authors [1,2] , interfacial slip between the GO flakes and PVA matrix was identified as a key mechanism in the mechanical behavior of the nanocomposite, and a modified Mori-Tanaka (M-T) approach was developed to accommodate the effect of slip. The modified M-T method was employed to model the stress–strain response of the PVA-GO nanocomposite at various strain rates, and close agreement between the theoretical and experimental results was observed. The rate sensitivity of PVA and its nanocomposites was analyzed by determining the initial elastic stiffness of specimens and their stress corresponding to a strain of 0.1, as functions of logarithmic strain rate (log (ε ˙)); it was found that both these parameters increase linearly with log (ε ˙). Moreover, the rate of increase in initial elastic stiffness with log (ε ˙) increases with GO content. In terms of the relationship between the stress at a strain of 0.1 and the logarithmic strain rate (log ε ˙), both PVA and its nanocomposites display curves with similar profiles. [ABSTRACT FROM AUTHOR]

• Study of quasi-static uniaxial loading-unloading tensile response of a PVA-graphene oxide nanocomposite. • Identification of interfacial slip between polymer matrix and filler as a significant factor for the stress-strain response. • Development of an interfacial slip model using finite elements to simulate filler-matrix interaction when interfacial slip occurs. • Incorporation of interfacial slip model into Mori-Tanaka theory to analyze the large deformation stress-strain response of the graphene oxide polymer nanocomposite. A novel modified Mori-Tanaka (M-T) approach to modeling the stress-strain response of graphene nanocomposites subjected to large deformation is described. It is hypothesized that slip at the filler-matrix interface occurs, and this limits the stress which can be transferred to the filler through the interface. Although interfacial slip has a significant influence on the mechanical response of polymer nanocomposites, the M-T method, commonly employed to model nanocomposites, does not accommodate this effect. A pseudo-filler phase is defined to represent the filler when interfacial slip occurs, and this is modeled using finite elements to simulate a single filler flake encapsulated by the interface, interacting with the matrix. The stiffness of the pseudo-filler is determined by examination of the variation of stress in the filler when interfacial slip occurs; this interfacial slip model is incorporated into the M-T method. Quasi-static tensile loading and unloading tests were conducted on polyvinyl alcohol (PVA)-graphene oxide (GO) nanocomposite samples, and significant enhancement of the stress-strain response of the nanocomposite was observed by the addition of GO; e.g. a 5 wt% GO addition increases the initial elastic modulus of PVA from 330 MPa to 1.29 GPa. The modified M-T method was used to simulate the stress-strain response of the nanocomposites, and the theoretical results compare well with experimental stress-strain data for both loading and unloading. Image, graphical abstract [ABSTRACT FROM AUTHOR]