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Gene delivery has emerged as a novel and effective method in the treatment of malignancies within medical interventions by applying nanotechnology. Consequently, the development of appropriate nanocarriers is a key focus of this research. Dynamic light scattering (DLS), fourier transform infrared (FT-IR) spectroscopy, x-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were employed for the characterization of the synthesized nanocarrier. Furthermore, to assess the gene transfer capability of the nanocarrier, various techniques such as gel retardation assay, nuclease resistance assay, cytotoxicity assay, flow cytometry, and transfection were employed. The average particle size and zeta potential of the GO-CS@Ca nanocarrier were obtained as 319.8 nm and + 92.8 mv, respectively. In the gel retardation test, it was observed that pDNA was effectively condensed by the GO-CS@Ca nanocarrier. The results of the MTT assay indicated that both GO-CS@Ca nanocarrier and the GO-CS@Ca/pDNA nanoplex with low toxicity. In flow cytometry analysis, it was observed that the complexation of pDNA with the GO-CS@Ca nanocarrier resulted in effective gene delivery to the MCF-7 cell line and consequently increased apoptosis induction. [ABSTRACT FROM AUTHOR]

Abstract Gene delivery has emerged as a novel and effective method in the treatment of malignancies within medical interventions by applying nanotechnology. Consequently, the development of appropriate nanocarriers is a key focus of this research. Dynamic light scattering (DLS), fourier transform infrared (FT-IR) spectroscopy, x-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were employed for the characterization of the synthesized nanocarrier. Furthermore, to assess the gene transfer capability of the nanocarrier, various techniques such as gel retardation assay, nuclease resistance assay, cytotoxicity assay, flow cytometry, and transfection were employed. The average particle size and zeta potential of the GO-CS@Ca nanocarrier were obtained as 319.8 nm and + 92.8 mv, respectively. In the gel retardation test, it was observed that pDNA was effectively condensed by the GO-CS@Ca nanocarrier. The results of the MTT assay indicated that both GO-CS@Ca nanocarrier and the GO-CS@Ca/pDNA nanoplex with low toxicity. In flow cytometry analysis, it was observed that the complexation of pDNA with the GO-CS@Ca nanocarrier resulted in effective gene delivery to the MCF-7 cell line and consequently increased apoptosis induction.

The low-friction mechanism of graphene oxide-dispersed lubricants remains to be elucidated. In this study, pin-on-disk friction tests were conducted on specimens with various surface properties to clarify the effect of the lubrication condition of the contact point on the low-friction by dispersing graphene oxide (GO) particles into lubricating oil. The relationship between the lubrication state and the friction coefficient was investigated using Λ ratio calculated from the surface roughness of the sliding area after the test and the calculated minimum oil film thickness. The friction coefficient decreased as Λ ratio increased, that is, as the lubrication state approached fluid lubrication. For the disk specimen containing pit shapes on the surface, the friction coefficient was significantly reduced by up to 70% for the graphene oxide-dispersed lubricant compared to the base oil alone. On the other hand, the friction reduction was only 20% for the specimen without pits. The composite surface roughness of the sliding area after the test was significantly improved for the disk with pits, which indicates that the progress of running-in process during the test affects the friction properties of the GO containing lubricant.

In this research, we have developed solid MGOs by self-assembled reduction process of GO at 90 °C with different weight ratios of oxalic acid (1:1, 1:0.500, and 1:0.250). The as-synthesized monoliths were carbonized (at 600 °C) and chemically activated with varying proportions of NaOH (1:1, 1:2, and 1:3). This materials offer the CO2 adsorption effect under dynamic conditions, fast mass transfer, easy handling, and outstanding stability throughout the adsorption-desorption cycle. FE-SEM, and HR-TEM analyses confirmed the porous nature and shape of the adsorbents, while XPS examination revealed the presence of distinct functional groups on the surface of the monolith. By increasing the mass ratios (MGO:NaOH) from 1:1 to 1:2, the surface areas increased by approximately 2.6 times, ranging from 520.8 to 753.9 m2 g⁻1 (surface area of the untreated MGO was 289.2 m2 g⁻1). Consequently, this resulted in a notable enhancement of 2.10 mmol g⁻1 in dynamic CO2 capture capacity. The assessment encompassed the evaluation of production yield, selectivity, regenerability, kinetics, equilibrium isotherm, and isosteric temperatures of adsorption (Qst). The decrease in CO2 capture effectiveness with rising adsorption temperature indicated an exothermic and physisorption process. The regenerability of 99.1 % at 100 °C and excellent cyclic stability with efficient CO2 adsorption make this monolithic adsorbent appropriate for post-combustion CO2 capture. The significant Qst lend support to the heterogeneity of the adsorbent's surface, and the pseudo-second-order kinetic model along with the Freundlich isotherm model emerged as the most fitting. Therefore, the current investigation shows that the carbon-enriched adsorbents enhance the CO2 adsorption capacity. It may be used as a low-cost pretreatment method on an industrial scale before carbon capture.

Monitoring the quality of drinking water is a crucial responsibility for all water infrastructure networks, as it guarantees access to clean water for the communities they serve. With water infrastructure deteriorating due to age and neglect, drinking water violations are on the rise in the US, underscoring the need for improved monitoring capabilities. Among the different sensor technologies, graphene-based chemiresistors have emerged as a promising technology for water quality monitoring due to advantages such as simple design, sensitivity, and selectivity. This review paper provides an overview of recent advances in the development of graphene-based chemiresistors for water quality monitoring, including principles of chemiresistive sensing, sensor design and functionalization, and performance of devices reported in the literature. The paper also discusses challenges and opportunities in the field and highlights future research directions. The development of graphene-based chemiresistors has the potential to revolutionize water quality monitoring by providing highly sensitive and cost-effective sensors that can be integrated into existing infrastructure for real-time monitoring. [ABSTRACT FROM AUTHOR]

The degradation of Nafion membrane easily occurs after a long run of proton exchange membrane fuel cell. Graphene-oxide (GO) is regarded as an ideal material to form composite membrane. In this work, a multistate empirical valence bond (MS-EVB) method and molecular dynamics method are employed to investigate the effect of GO on transport and solvation characteristics of protons in the degraded hydration membrane. The hydrophilic cluster and its connectivity are analyzed. The interaction between GO, Nafion membrane and water molecules is discussed. The influence of GO on the thermal conduction of Nafion membrane is also evaluated. The results demonstrate that with the addition of GO, the water cluster connectivity of Nafion membrane becomes better. The distribution of hydronium ions and membranes in the water is more uniform, which increases the proton conductivity. The larger GO may not interact well with water molecules, but promotes the thermal conductivity of degraded Nafion membrane more obviously. • MD simulation is conducted for degraded membrane with graphene oxide. • Impact of graphene oxide size on degraded membrane is analyzed. • Influence of graphene oxide on thermal conduction of membrane is evaluated. [ABSTRACT FROM AUTHOR]

Supercapacitors formed from porous carbon and graphene‐oxide (GO) materials are usually dominated by either electric double‐layer capacitance, pseudo‐capacitance, or both. Due to these combined features, reduced GO materials have been shown to offer superior capacitance over typical nanoporous carbon materials; however, there is a significant variation in reported values, ranging between 25 and 350 F g−1. This undermines the structure (e.g., oxygen functionality and/or surface area)‐performance relationships for optimization of cost and scalable factors. This work demonstrates important structure‐controlled charge storage relationships. For this, a series of exfoliated graphene (EG) derivatives are produced via thermal‐shock exfoliation of GO precursors and following controlled graphitization of EG (GEG) generates materials with varied amounts of porosity, redox‐active oxygen groups and graphitic components. Experimental results show significantly varied capacitance values between 30 and 250 F g−1 at 1.0 A g−1 in GEG structures; this suggests that for a given specific surface area the redox‐active and hydrophilic oxygen content can boost the capacitance to 250–300% higher compared to typical mesoporous carbon materials. GEGs with identical oxygen functionality show a surface area governed capacitance. This allows to establish direct structure‐performance relationships between 1) redox‐active oxygen functional concentration and capacitance and 2) surface area and capacitance. [ABSTRACT FROM AUTHOR]

In recent years, nano-sized graphene oxide (GO) has come to the fore as a promising material for enhancing the mechanical and durability performance of cementitious composites. On the other hand, partial substitution of industrial wastes and by-products into cementitious composites attracts the attention of researchers in order to ensure long-term sustainability. In order to combine these two aspects, the main focus of this study is to examine the effect of 0.05% and 0.1% GO-reinforcement on the slump, 7 and 28-day compressive and flexural strength and 28-day rapid chloride permeability test (RCPT) properties of cementitious composites. In this context, mixtures with three different binder combinations, a control, a silica fume (SF) substitution, and a fly ash (FA) substitution, were designed. The results showed that GO-reinforcement reduced the slump values of the mixtures between 5-15 mm, while the 28-day compressive strengths increased in the range of 9.82%-13.61% with 0.05% GO-reinforcement, and in the range of 17.02%-20.68% with 0.1% GO-reinforcement. The 28-day flexural strength of the mixtures increased by about 10% on average as a result of 0.1% GO-reinforcement. According to the RCPT anaylses, it was observed that the chloride permeability of the mixtures decreased up to 18.85% with 0.1% GO-reinforcement. [ABSTRACT FROM AUTHOR]

The constant concern about environmental issues has led to the growth of researches about eco-friendly materials. Among them, the natural lignocellulosic fibers have already presented their potential in place of petroleum-based synthetics. However, a relevant number of studies still have to deal with their disadvantages, such as the weak bond on the matrices for a composite performance and limited thermal performance. Thus, the present study analyzes a combination of alkaline treatment and graphene oxide coating in hemp fibers, an NLF applied in several products but with few investigations in engineering applications. The hemp fibers were thermally characterized with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The GO-coating was evidenced by the Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Changes in crystallinity were presented by X-ray diffraction (XRD). It was observed an increase of about 4% to 11% of the crystallinity after the alkaline treatment. The thermal stability rose about 13°C in the 10 wt% NaOH-treated and GO-coated fibers, and a change of about 3.5°C was detected for the glass transition temperature. The GO-coating effect was also evidenced by changes in Raman spectra and FTIR curves and was visually detected in the scanning electron microscope (SEM).

Interfaces between nacreous tablets are crucial to the outstanding mechanical properties of nacre in natural shells and inspired by the “brick-and-mortar ” structure and remarkable mechanical performance of nacre. Excellent research has been conducted to probe the effect of interfaces on strength and toughness of nacre, providing critical guidelines for the design of human-made laminated composites. Herein, a class of graphene oxide (GO) based artificial nacre composite material with self-healing capacity due to non-covalent bonding interactions was fabricated by functionalization of GO with ellagic acid through π-π stacking followed by evaporation-induced self assembling process between ellagic acid modified graphene oxide(EGO) and polyurethane(PU). The artificial nacre displays a strict “brick-and-mortar ” structure, with EGO nanosheets as the brick and PU as the mortar. The structure of EGO was characterized by infrared spectroscopy, potential analyzer and X-ray diffraction, and the mechanical properties of PU-EGO were tested by universal testing machine. The results show that ellagic acid (ELA) is successfully adsorbed on GO surface, and when the mass ratio of PU to EGO is 3∶1, the tensile strength and toughness of the material reach 111.2 MPa and 81.5 MJ/m3, respectively (9.6 times and 1.8 times higher than that of PU), attributing to the interlayer slip of GO by breaking and recombing the π-π bond dynamically through which the energy can dissipate when PU-EGO is subjected to tensile stress. In addition, owning to the existence of noncovalent bonds, the resulting polymer composites display good recyclability. This work provides a pathway for the development of artificial nacre with self-healing capacity and recyclability. [ABSTRACT FROM AUTHOR]

In this study, the authors have designed biocompatible nano-vesicles using graphene oxide (GO) for the release of chlorambucil (CHL) drugs targeting cancerous cells. The GO sheets were first sulfonated and conjugated with folic acid (FA) molecules for controlled release and high loading efficiency of CHL. The chlorambucil (CHL) drug loading onto the functionalized GO surface was performed through π-π stacking and hydrophobic interactions with the aromatic planes of GO. The drug loading and "in vitro" release from the nano-vesicles at different pH were studied. The average particle size, absorption, and loading efficiency (%) of FA-conjugated GO sheets (CHL-GO) were observed to be 300 nm, 58%, and 77%, respectively. The drug release study at different pH (i.e., 7.4 and 5.5) showed a slight deceleration at pH 7.4 over pH 5.5. The amount of drug released was very small at pH 7.4 in the first hour which progressively increased to 24% after 8 h. The rate of drug release was faster at pH 5.5; initially, 16% to 27% in the first 3 h, and finally it reached 73% after 9 h. These observations indicate that the drug is released more rapidly at acidic pH with a larger amount of drug-loading ability. The rate of drug release from the CHL-loaded GO was 25% and 75% after 24 h. The biotoxicity study in terms of % cell viability of CHL-free and CHL-loaded GO against human cervical adenocarcinoma cell line was found to have lower cytotoxicity of CHL-loaded nano-vesicles (IC50 = 18 μM) as compared to CHL-free (IC50 = 8 μM). It is concluded that a high drug-loading efficiency and controlled release with excellent biotoxicity of CHL-GO offers an excellent application in the biomedical field. [ABSTRACT FROM AUTHOR]

Monitoring the quality of drinking water is a crucial responsibility for all water infrastructure networks, as it guarantees access to clean water for the communities they serve. With water infrastructure deteriorating due to age and neglect, drinking water violations are on the rise in the US, underscoring the need for improved monitoring capabilities. Among the different sensor technologies, graphene-based chemiresistors have emerged as a promising technology for water quality monitoring due to advantages such as simple design, sensitivity, and selectivity. This review paper provides an overview of recent advances in the development of graphene-based chemiresistors for water quality monitoring, including principles of chemiresistive sensing, sensor design and functionalization, and performance of devices reported in the literature. The paper also discusses challenges and opportunities in the field and highlights future research directions. The development of graphene-based chemiresistors has the potential to revolutionize water quality monitoring by providing highly sensitive and cost-effective sensors that can be integrated into existing infrastructure for real-time monitoring.

This paper presents the electrochemical properties of graphene-oxide composites and nanoparticles of cobalt-ferrite, as well as cobalt-ferrite doped with zinc and gallium. Graphene-oxide (GO) was synthesized by a modified Hummer's method. The magnetic nanoparticles were synthesized by the solvothermal method, after which the oleic acid was exchanged with dihydrocaffeic acid to obtain the hydrophilic material. Composites of graphene-oxide and magnetic nanoparticles were synthesized by the hydrothermal method, where the share of magnetic particles was 5 and 15 wt.% on graphene-oxide. The results of X-ray structural and FTIR analysis confirmed the complete oxidation of graphene layers. SEM and TEM analyzes showed deposition of magnetic nanoparticles on the graphene-oxide layer, without changing the size or shape of the nanoparticles. FTIR analysis of hydrothermally treated graphene oxide and composites showed that there is a partial reduction of epoxy groups, also a hydrogen bond is established between the components of the composite. Cyclic voltammograms show that the composites are stable at polarization rates of 5-400 mV s-1 , and that their capacity is predominantly pseudocapacitive in nature. Pseudocapacitance originates from the oxidoreduction reactions of H+ ions from electrolytes and surface functional groups of graphene-oxide. Based on the cyclic voltammograms, the specific capacities of all composites were calculated and the highest value being shown by the CFO_GO_15% composite, which is 36.86 F g-1 at a polarization rate of 5 mV s-1 .

Graphene oxide (GO) sheets have been used successfully as a supporting substrate film in several recent cryogenic electron-microscopy (cryo-EM) studies of challenging biological macromolecules. However, difficulties in preparing GO-covered holey carbon EM grids have limited their widespread use. Here, we report a simple and robust method for covering holey carbon EM grids with GO sheets and demonstrate that these grids can be used for high-resolution single particle cryo-EM. GO substrates adhere macromolecules, allowing cryo-EM grid preparation with lower specimen concentrations and provide partial protection from the air-water interface. Additionally, the signal of the GO lattice beneath the frozen-hydrated specimen can be discerned in many motion-corrected micrographs, providing a high-resolution fiducial for evaluating beam-induced motion correction.

The constant concern about environmental issues has led to the growth of researches about eco-friendly materials. Among them, the natural lignocellulosic fibers have already presented their potential in place of petroleum-based synthetics. However, a relevant number of studies still have to deal with their disadvantages, such as the weak bond on the matrices for a composite performance and limited thermal performance. Thus, the present study analyzes a combination of alkaline treatment and graphene oxide coating in hemp fibers, an NLF applied in several products but with few investigations in engineering applications. The hemp fibers were thermally characterized with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The GO-coating was evidenced by the Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Changes in crystallinity were presented by X-ray diffraction (XRD). It was observed an increase of about 4% to 11% of the crystallinity after the alkaline treatment. The thermal stability rose about 13°C in the 10 wt% NaOH-treated and GO-coated fibers, and a change of about 3.5°C was detected for the glass transition temperature. The GO-coating effect was also evidenced by changes in Raman spectra and FTIR curves and was visually detected in the scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

This study investigates the influence of reduced graphene oxide (rGO) coated glass fabrics on the strain sensing and the mechanical characteristics of fiber‐reinforced composites. Graphene oxide was applied in two thicknesses (threefold and fivefold coatings) onto a fabric using a padder mangle machine followed by thermal reduction and infused with an epoxy to manufacture rGO‐enhanced composite. The tensile modulus and flexural strength of the rGO‐enhanced composites with threefold coating were improved by 27% and 6.2%, respectively, compared with the equivalent composite manufactured without rGO. The normalized resistance (ΔR/R0) of composites increased by 0.89% and 3.48% under a cyclic tensile force of 1000 and 4000 N. The magnitude of ΔR/R0 was stable within 30 cycles suggesting a consistent strain sensing performance with a gauge factor of 15.55. The electrical response of the rGO‐enhanced composite was evaluated using a new industrial standard for sensors, by assessing calibration curves. The composite showed low hysteresis and low electrical viscosity which make these materials suitable for industrial piezoresistive strain sensors. [ABSTRACT FROM AUTHOR]

Lead-free perovskite solar cells (PSCs) have sparked considerable interest in the optoelectronics research community and gained recognition in recent years due to their practical use in solar energy. The primary obstacles in producing PSCs are stability and toxicity due to the immersion of organic-cation and lead in perovskite material. This study presents an electrical simulation of a caesium–indium-based lead-free hybrid PSC using SCAPS-1D software. Spiro-MeOTAD is a typical hole transport material (HTM) used in PSC, although it has not always been suggested because of its high design cost and stability constraints. This study aims to evaluate the performance of lead-free double perovskite material as an absorber layer along with different hole transport materials (HTM). We discovered that the lead-free double perovskite combined with graphene-oxide (GO) and reduced graphene oxide (rGO) produces the best results. Furthermore, the light-harvesting layer and HTM layer has optimized via thickness, defects, doping concentration, and temperature. The improved PSC structure achieves power conversion efficiency (PCE) of more than 24%, and the results of the optimized PSC have compared to the results of the experimentally implemented PSC. This work also used C–V measurements on the optimized structure to determine the device contact potential and doping concentration. The optimized results suggest a feasible future route for creating lead-free PSC with high productivity and free from stability or toxicity issues. [ABSTRACT FROM AUTHOR]

In this work, we report on the fabrication and photonic activation of a novel kind of photomobile polymer (PMP) film based mainly on a double layered asymmetric configuration. The PMP is cheap and extremely easy to make. It is made of PVC/isoprene tape with a layer of graphene-oxide (GO) attached. Under illumination at different intensities, and with coherent and incoherent light sources, the bending of the PMP film changes considerably. In particular, we noticed a more efficient bending effect when the film is directly exposed to high light intensities or to NIR radiation in the case of incoherent light sources. For the exposure times used in our experiments, the process is completely reversible when the light source is switched off. Additionally, if we paint the side of the PVC tape exposed to light black, the film is not able to return to its starting position and the bending results are permanent. This suggests that the presence of the GO-layer is responsible for the restoration of the position of the PMP film. [ABSTRACT FROM AUTHOR]

Lower alcohols have long been the figureheads of diesel/biodiesel additives in characterizing renewable fuels. Next-generation alcohol like n-octanol occupied the reified position due to their better fuel properties. In this paper, combustion, performance and, emission of different graphene-oxide nanoparticles (nanoGO) added jatropha biodiesel, n-octanol and petrodiesel blends are investigated in a 4-stroke DI diesel engine. This article also aims to optimize the engine inputs accountable for better performance and emission characteristics of a diesel engine running with nanoGO dispersed biodiesel/diesel/higher alcohol blends. Full Factorial Design-based Response Surface Methodology (RSM) is utilized to model the experiments using Design-Expert software to optimize engine responses. Validation of the developed model is carried out using sophisticated error and performance metrics, namely, TheilU2, Kling-Gupta Efficiency (K-G Eff), and Nash-Sutcliffe coefficient of efficiency (N-S Eff) along with the conventional statistical database. The model optimized engine inputs of 3.898% n-Octanol, and 49.772 ppm nanoGO at 99.2% load with a desirability index of 0.997 as the optimum engine parameters. The experimental validation revealed that the model optimized blend at full load witnessed a reduction of 15.6% CO, 21.78% HC.u, and 3.26% NOx emission compared to petrodiesel. However, a slight increase in brake specific energy consumption (2.95%) is also recorded because of the lower heating value of the blend. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphene oxide synthesis from used C-type batteries by electrochemical exfoliation. • Graphene oxide reduction using series of reduction methods. • Electrochemical analysis of reduced-GO (rGO) at each stage of reduction process. • rGO produced by water-based annealing has highest capacitance among rGO samples. • Capacitance is highest with maximum C-O functionalities and reduces as they decrease. Graphene oxide (GO) is reduced multiple times in sequence with different reduction techniques. Changes in capacitance of reduced graphene oxide (rGO) at each stage in multistep reduction process are evaluated as function of variations in oxygen functionalities. Physical and electrochemical properties of rGO samples are rigorously examined at each stage of reduction. rGO produced following microwave-reduction has the highest reduction effect as compared to other reduction steps. rGO produced after water-based reduction (rGO(W)) has the highest capacitance of 93.136F.g−1. Similarly, the C1s XPS spectra at each stage of reduction reveal that, the rGO(W) sample has the highest C-O contribution among all the rGO samples. It is also noticed that capacitance of rGO samples drops as the oxygen functionalities decrease. [ABSTRACT FROM AUTHOR]

Graphene is the material elected to study molecules and monolayers at the molecular scale due to its chemical stability and electrical properties. The invention of scanning tunneling microscopy has deepened our knowledge on molecular systems through imaging at an atomic resolution, and new possibilities have been investigated at this scale. Interest on studies on biomolecules has been demonstrated due to the possibility of mimicking biological systems, providing several applications in nanomedicine: drug delivery systems, biosensors, nanostructured scaffolds, and biodevices. A breakthrough came with the synthesis of molecular systems by stepwise methods with control at the atomic/molecular level. This article presents a review on self-assembled monolayers of biomolecules on top of graphite with applications in biodevices. Special attention is given to porphyrin systems adsorbed on top of graphite that are able to anchor other biomolecules. [ABSTRACT FROM AUTHOR]

In this work, the effect of graphene oxide (GO) on the physical performance related properties of an asphalt binder was investigated in terms of penetration, softening point, viscosity (110–185°C), and ductility as well as temperature performance indices. Subsequently, response surface methodology (RSM) was used to examine the influence of GO and asphalt contents on the volumetric and strength properties of the asphalt mixture. Marshall stability/flow and indirect tensile strength (ITS) tests were performed on the compacted mixtures. Then, the RSM based on the central composite design (CCD) was utilised to analyse the effects of the preparation parameters and conduct mathematical modelling for the response variables' predictions. According to the results, the addition of GO significantly enhanced the physical properties of the asphalt. The RSM analysis showed that the tensile strength, stability, and plastic flow, coupled with the volumetric characteristics of the asphalt mixture were highly influenced by variations in the preparations. The proposed models were well-fitted to the actual results with a high degree of correlation. Furthermore, numerical optimisation results presented 1.8% of the GO and 5.3% of the asphalt content as the optimum proportions of the mixture to achieve the maximum desired responses. [ABSTRACT FROM AUTHOR]

This work demonstrates the graphene oxide (GO) RRAM exhibiting low-power, low-voltage multilevel resistive switching when clamped to an oxygen vacancy rich bismuth ferrite (BFO) thin film. The GO/BFO structure also shows stable endurance characteristics with a larger memory window due to the accumulation of excess oxygen vacancies. The conduction process in pristine GO does not suffer larger distortion when it is stacked to BFO and follows Ohmic and trap-assisted space charge limited current conduction mechanism. In GO RRAM, Ag+ ion-induced conducting filament is primarily responsible for the switching process, while oxygen vacancies are dominating in bilayer device. The GO/BFO exhibits intermediate resistive states during the RESET process due to multiple breakdowns of conducting paths. At least a 4-bit multistate data storage configuration is demonstrated by tuning the pulse-amplitude of RESET from 2 to 5 V at a constant SET voltage of − 3 V. Thereafter, a 3-bit multilevel storage device can be configured in GO/BFO by tuning the pulse-width from 10 to 30 µs, which takes place at lower time scale than the BFO. Our findings suggest the possibility of ultrafast, multilevel RRAM for next-generation high-density memories and neuromorphic computing applications. [ABSTRACT FROM AUTHOR]

In this study, the authors have designed biocompatible nano-vesicles using graphene oxide (GO) for the release of chlorambucil (CHL) drugs targeting cancerous cells. The GO sheets were first sulfonated and conjugated with folic acid (FA) molecules for controlled release and high loading efficiency of CHL. The chlorambucil (CHL) drug loading onto the functionalized GO surface was performed through π-π stacking and hydrophobic interactions with the aromatic planes of GO. The drug loading and “in vitro” release from the nano-vesicles at different pH were studied. The average particle size, absorption, and loading efficiency (%) of FA-conjugated GO sheets (CHL-GO) were observed to be 300 nm, 58%, and 77%, respectively. The drug release study at different pH (i.e., 7.4 and 5.5) showed a slight deceleration at pH 7.4 over pH 5.5. The amount of drug released was very small at pH 7.4 in the first hour which progressively increased to 24% after 8 h. The rate of drug release was faster at pH 5.5; initially, 16% to 27% in the first 3 h, and finally it reached 73% after 9 h. These observations indicate that the drug is released more rapidly at acidic pH with a larger amount of drug-loading ability. The rate of drug release from the CHL-loaded GO was 25% and 75% after 24 h. The biotoxicity study in terms of % cell viability of CHL-free and CHL-loaded GO against human cervical adenocarcinoma cell line was found to have lower cytotoxicity of CHL-loaded nano-vesicles (IC50 = 18 μM) as compared to CHL-free (IC50 = 8 μM). It is concluded that a high drug-loading efficiency and controlled release with excellent biotoxicity of CHL-GO offers an excellent application in the biomedical field.

This work presents a gas-liquid sensor based on chalcogenide etched-tapered fiber (ETF) functionalized with graphene oxide film. Unlike the preparation of conventional tapered fiber sensors, the core diameter of the optical fiber of this gas-liquid sensor was kept constant, and part of its cladding was removed via the chemical corrosion method that the fiber optic modes were the invariant. The energy distribution of transmission mode in the original fiber and tapered fiber is simulated respectively, and obtained the conclusion that the tapered fiber structure has higher sensing sensitivity. The sensors could detect VOCs such as formaldehyde (HCOH) and butane (C4H10) in the mid-infrared band. Results showed that the ETF sensor had a high detection sensitivity of both HCOH solution (2.6731 a.u./mg·mL−1) and C4H10 gas (0.2773 a.u./vol.%). A layer of graphene oxide (GO) film was coated on the ETF to further improve the sensitivity of the sensor. The GO coated etched-tapered fiber (GO-ETF) sensor’ sensitivity was substantially improved owing to the strong hydrophilicity and biocompatibility of GO which can absorb bioactive molecules. The high detection sensitivity of both solution and gas were 4.5091 a.u./mg·mL−1 and 0.4812 a.u./vol.%, respectively, which were 1.69 and 1.74 times higher than that of the sensor without a coating of GO film. The results further showed that the sensor had a rapid response speed, low detection limit, good repeatability, and stability. [ABSTRACT FROM AUTHOR]

The main focus of these investigations is to introduce a simple, eco-friendly technique for producing high quality sheets of reduced graphene oxide (rGO) by applying an ultrahigh energy laser, coupled with sonication, as an energetic thermal effect promoter to replace removal of oxygen by treating graphene oxide (GO) with ordinary thermal treatments or a combination of chemical and thermal processes. The results indicated that doses from an industrial ultrahigh energy laser with an output of 1650W. coupled with sonication, suffice to reduce graphene oxide (GO) and convert it into reduced graphene oxide (rGO) within the range of a 60-minute experiment. Raman spectra, x-ray diffraction and atomic force microscopy were used to confirm the presence and measure the structure quality of the reduced form of graphene oxide. Results obtained confirmed that applied laser doses coupled with sonication succeeded to produce rGO with good structural features. [ABSTRACT FROM AUTHOR]

This study focuses on enhancing nanostructured ZnO thin films ammonia (NH 3) sensing capabilities at room temperature by integrating graphene-oxide (GO) via the drop-casting technique, thereby exploring the possibilities of tailoring NH 3 sensing measurements. Structural investigations indicated the hexagonal-wurtzite structure of the sputtered ZnO and GO-decorated thin films. The Raman spectroscopy results validate the electrochemically exfoliated GO, and the X-ray photoelectron spectroscopy characterization revealed the Zn2+ state and oxygen vacancies. The NH 3 gas sensing measurements for GO/ZnO revealed a remarkable increase in sensitivity, with a limit of detection (LOD) of 0.1 ppm. This exhibited a response 50 times superior to bare ZnO for 5 ppm of NH 3 at room temperature (RT). As a result of decorating GO increased active sites and surface area. This significant enhancement in sensor response underscores the synergistic effect of GO-decoration, and ZnO leading to substantially improved gas-detecting capabilities. The NH 3 sensing mechanism of GO/ZnO thin film. [Display omitted] • ZnO thin films were fabricated through DC reactive magnetron sputtering. • Graphene oxide (GO) was prepared via the one-pot synthesis of the electrochemical exfoliation method. • The GO decorated ZnO sensor exhibited an extensive detection range from 0.1 to 100 ppm, enhancing a remarkable limit of detection at 0.1 ppm. • This represents a substantial 50-fold improvement compared to the sensitivity of pristine ZnO. • Response-recovery times of 26 and 86 s were observed towards 0.1 ppm of NH3. [ABSTRACT FROM AUTHOR]

Background and Aim: Endocrine Disrupting Chemicals (EDCs), and potential EDCs are mostly man-made, found in various materials such as pesticides, metals, additives or contaminants in food, and personal care products. Phthalates are a group of these compounds that are carcinogenic to animals and can cause fetal death and congenital anomalies. The aim of this study was to investigate the photocatalytic process using GO/ZnO nanocomposites under LED irradiation for removal of Endocrine Disrupting Chemicals (EDCs) from aqueous solutions. Materials and Methods: In this study, GO/ZnO nanorods were characterized by, Field emission scanning electron microscopy, transmission electron microscope, and Brunauer–Emmett–Teller surface area analysis. A Central Composite Design was used to optimize the reaction parameters for the removal of DEP by GO/ZnO. The four main reaction parameters optimized in this study were the following: the LED radiation time, pH, and the initial concentration of phthalates and the concentration of ZnO and graphene-oxide. The interaction between the four parameters was studied and modeled using the Design Expert 10 software. Phthalate detected by HPLC apparatus equipped with a UV detector at 225 nm wavelength with methanol (90%) and Acetonitrile (10%) phases. Results: The results of FE-SEM and TEM showed that the ZnO is composed of a bar and separate face. Based on the peak obtained, the diameter and length of the nanorods are 20-60 and 200 nm respectively. A maximum reduction of 90% of DEP was achieved at pH 5 and 120 minutes. The results represent the prediction of a model fitted from the Quadratic model (p-value

Background and Aim: Endocrine Disrupting Chemicals (EDCs), and potential EDCs are mostly man-made, found in various materials such as pesticides, metals, additives or contaminants in food, and personal care products. Phthalates are a group of these compounds that are carcinogenic to animals and can cause fetal death and congenital anomalies. The aim of this study was to investigate the photocatalytic process using GO/ZnO nanocomposites under LED irradiation for removal of Endocrine Disrupting Chemicals (EDCs) from aqueous solutions. Materials and Methods: In this study, GO/ZnO nanorods were characterized by, Field emission scanning electron microscopy, transmission electron microscope, and Brunauer–Emmett–Teller surface area analysis. A Central Composite Design was used to optimize the reaction parameters for the removal of DEP by GO/ZnO. The four main reaction parameters optimized in this study were the following: the LED radiation time, pH, and the initial concentration of phthalates and the concentration of ZnO and graphene-oxide. The interaction between the four parameters was studied and modeled using the Design Expert 10 software. Phthalate detected by HPLC apparatus equipped with a UV detector at 225 nm wavelength with methanol (90%) and Acetonitrile (10%) phases. Results: The results of FE-SEM and TEM showed that the ZnO is composed of a bar and separate face. Based on the peak obtained, the diameter and length of the nanorods are 20-60 and 200 nm respectively. A maximum reduction of 90% of DEP was achieved at pH 5 and 120 minutes. The results represent the prediction of a model fitted from the Quadratic model (p-value

In this work, we report on the fabrication and photonic activation of a novel kind of photomobile polymer (PMP) film based mainly on a double layered asymmetric configuration. The PMP is cheap and extremely easy to make. It is made of PVC/isoprene tape with a layer of graphene-oxide (GO) attached. Under illumination at different intensities, and with coherent and incoherent light sources, the bending of the PMP film changes considerably. In particular, we noticed a more efficient bending effect when the film is directly exposed to high light intensities or to NIR radiation in the case of incoherent light sources. For the exposure times used in our experiments, the process is completely reversible when the light source is switched off. Additionally, if we paint the side of the PVC tape exposed to light black, the film is not able to return to its starting position and the bending results are permanent. This suggests that the presence of the GO-layer is responsible for the restoration of the position of the PMP film.

Equine bone blocks have osteogenic effects promoting bone regeneration with biocompatibility and osteoconductivity capacity. Human dental pulp stem cells (hDPSCs) can differentiate into osteoblasts enhancing biomineralization with such scaffolds. Melatonin is able to improve bone health and mediate bone formation. Collagenated equine bone blocks were coated with ammonia-functionalized graphene-oxide (G-N) at two different concentrations (2 μg/mL, G-N2; and 10 μg/mL, G-N10). The homogeneity of G-N coating was checked by Raman spectroscopy, whereas thermogravimetric analysis (TGA) allowed us to quantify the amount of G-N deposited on the blocks. The aim of this study was to investigate in vitro the effect of G-N-coated collagenated equine bone blocks on the proliferation and differentiation of hDPSCs with the addition of a melatonin. This evaluation was determined after 7, 14, and 21 days of culture by the expression of specific microRNAs, RUNX2 and SMAD5 gene expression, osteocalcin levels, and histological analysis. The results showed that equine blocks G-N2 and G-N10 and melatonin gave an optimal cell adhesion as shown by histological analysis, and an increase in the hDPSCs osteogenic potential as confirmed by microRNA and gene expression with an increase in osteocalcin levels. This study suggests that equine bone blocks coated with G-N2 and G-N10 and melatonin promote the osteogenic process. [ABSTRACT FROM AUTHOR]

Graphene is the material elected to study molecules and monolayers at the molecular scale due to its chemical stability and electrical properties. The invention of scanning tunneling microscopy has deepened our knowledge on molecular systems through imaging at an atomic resolution, and new possibilities have been investigated at this scale. Interest on studies on biomolecules has been demonstrated due to the possibility of mimicking biological systems, providing several applications in nanomedicine: drug delivery systems, biosensors, nanostructured scaffolds, and biodevices. A breakthrough came with the synthesis of molecular systems by stepwise methods with control at the atomic/molecular level. This article presents a review on self-assembled monolayers of biomolecules on top of graphite with applications in biodevices. Special attention is given to porphyrin systems adsorbed on top of graphite that are able to anchor other biomolecules.

Successful exploration of supercapacitor (SC) material to integrate with high energy and high power density storage device still remains a daunting challenge. Conducting carbon nanostructures have been primarily used for this purpose; however, most of their surface area remains unutilized throughout the storage process. Herein, a new type of hybrid material has been reported by effectively using active sides of carbon nanostructures. Insertion of faradaic-type polyoxometalates (POMs), namely phosphotetradecavanadate (Na7[H2PV14O42, hereafter described as PV14), into the graphene oxide (GO) matrix creates a novel hybrid material for SC applications. Owing to the formation of nanohybrid, it can store charges both electrostatically and electrochemically. PV14/GO composite's electrochemical behavior in different electrolyte (acidic/neutral) solutions shows different types of characteristics. The PV14/GO composite as a working electrode exhibits a high galvanostatic capacitance of 139 F/g while maintaining at a power density of 97.94 W/kg in 0.25 M H2SO4 electrolyte. The specific energy density was also found out to be around 56.58 Wh/kg at a 5 mV/s scan rate for the same electrolyte. Furthermore, in 1 M Na2SO4 solution, PV14/GO composite demonstrates a specific capacitance of 85.4 F/g at a scan rate of 5 mV/s. The equivalent series resistance for the device was found to be approximately 0.51 Ω with a circuit resistance of 3.881 Ω, using electrochemical impedance spectroscopy. The cell capacitance, employing the Nyquist plot, was calculated to be around 2.78 mF. [ABSTRACT FROM AUTHOR]

Nowadays, pharmaceutical antibiotics are known as a serious class of pollutants. Therefore, it is important to develop effective methods for removing these pollutants from aqueous media. Different methods were applied for this purpose, and among these methods, chemical reduction by a cheap and eco‐friendly nanocatalyst is the most efficient and simplest method. In this research, based on graphene oxide supported by zero‐valent iron in mono‐, bi‐, and tri‐metallic systems, various nanocomposites were synthesized and used to degrade tetracycline as a model antibiotic from aqueous media. An investigation was carried out on the synergic effect among graphene oxide and the nano zero‐valent iron‐based tri‐metallic system as well as removal efficiencies. It was found that higher degradation efficiency is yielded by graphene oxide supported by Fe/Cu/Ag tri‐metallic system. The maximum synergic effect occurs at an acidic medium. The Brunauer–Emmett–Teller, Fourier transform spectroscopy, scanning electron microscopy‐energy dispersive X‐ray analysis, transmission electron microscopy, and X‐ray diffraction analysis were used to characterize the synthesized nanocomposites, which has successfully proved the loading of nanoscale Fe/Cu/Ag tri‐metallic on a graphene oxide support. The central composite design was used to model and optimize all involved variables affecting antibiotic removal efficiency. The consequences illustrated the optimum condition regarding the removal of 50 ppm of tetracycline, for the nanocomposites dose of 3.0 mg ml−1, the contact time of 30 min, and pH of 2, was achieved using the simplex non‐linear optimization method. Moreover, antibiotic adsorption kinetic models were also investigated. Finally, the tetracycline removal from aqueous media at different concentrations, 25, 50, and 75 ppm, was successful by applying the proposed nanocomposite, and the results showed tetracycline removal efficiencies of above 70%. [ABSTRACT FROM AUTHOR]

• Graphene oxide decorated with silica could act as perfect adsorbent. • Silica-decorated graphene oxide (SGO) was used as a high-efficiency adsorbent to remove Congo red (CR) and Cadmium (II) simultaneous from binary solutions. • The results suggested that the adsorption process was spontaneous and exothermic in nature. • Graphene oxide decorated with silica can be considered as a promising adsorbent for future water pollution control. Image, graphical abstract Graphene oxide is a very high capacity adsorbent due to its functional groups and π−π interactions with other compounds. Adsorption capacity of graphene oxide, however, can be further enhanced by having synergistic effects through the use of mixed-matrix composite. In this study, silica-decorated graphene oxide (SGO) was used as a high-efficiency adsorbent to remove Congo red (CR) and Cadmium (II) from aqueous solutions. The effects of solution initial concentration (20 to 120 mg/l), solution pH (pH 2 to 7), adsorption duration (0 to 140 min) and temperature (298 to 323 K) were measured in order to optimize the adsorption conditions using the SGO adsorbent. Morphological analysis indicated that the silica nanoparticles could be dispersed uniformly on the graphene oxide surfaces. The maximum capacities of adsorbent for effective removal of Cd (II) and CR were 43.45 and 333.33 mg/g based on Freundlich and Langmuir isotherms, respectively. Langmuir and Freundlich isotherms displayed the highest values of Q max for CR and Cd (II) adsorption in this study, which indicated monolayer adsorption of CR and multilayer adsorption of Cd (II) onto the SGO, respectively. Thermodynamic study showed that the enthalpy (ΔH) and Gibbs free energy(Δ G) values of the adsorption process for both pollutants were negative, suggesting that the process was spontaneous and exothermic in nature. This study showed active sites of SGO (π-π, hydroxyl, carboxyl, ketone, silane-based functional groups) contributed to an enormous enhancement in simultaneous removal of CR and Cd (II) from an aqueous solution, Therefore, SGO can be considered as a promising adsorbent for future water pollution control and removal of hazardous materials from aqueous solutions. [ABSTRACT FROM AUTHOR]

In this research, we have developed solid MGOs by self-assembled reduction process of GO at 90 °C with different weight ratios of oxalic acid (1:1, 1:0.500, and 1:0.250). The as-synthesized monoliths were carbonized (at 600 °C) and chemically activated with varying proportions of NaOH (1:1, 1:2, and 1:3). This materials offer the CO 2 adsorption effect under dynamic conditions, fast mass transfer, easy handling, and outstanding stability throughout the adsorption-desorption cycle. FE-SEM, and HR-TEM analyses confirmed the porous nature and shape of the adsorbents, while XPS examination revealed the presence of distinct functional groups on the surface of the monolith. By increasing the mass ratios (MGO:NaOH) from 1:1 to 1:2, the surface areas increased by approximately 2.6 times, ranging from 520.8 to 753.9 m 2  g⁻ 1 (surface area of the untreated MGO was 289.2 m 2  g⁻ 1 ). Consequently, this resulted in a notable enhancement of 2.10 mmol g⁻ 1 in dynamic CO 2 capture capacity. The assessment encompassed the evaluation of production yield, selectivity, regenerability, kinetics, equilibrium isotherm, and isosteric temperatures of adsorption (Q st ). The decrease in CO 2 capture effectiveness with rising adsorption temperature indicated an exothermic and physisorption process. The regenerability of 99.1 % at 100 °C and excellent cyclic stability with efficient CO 2 adsorption make this monolithic adsorbent appropriate for post-combustion CO 2 capture. The significant Q st lend support to the heterogeneity of the adsorbent's surface, and the pseudo-second-order kinetic model along with the Freundlich isotherm model emerged as the most fitting. Therefore, the current investigation shows that the carbon-enriched adsorbents enhance the CO 2 adsorption capacity. It may be used as a low-cost pretreatment method on an industrial scale before carbon capture., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier Ltd.)

The use of graphene and its derivatives in the development of electrochemical sensors has been growing in recent decades. Part of this success is due to the excellent characteristics of such materials, such as good electrical and mechanical properties and a large specific surface area. The formation of composites and nanocomposites with these two materials leads to better sensing performance compared to pure graphene and conductive polymers. The increased large specific surface area of the nanocomposites and the synergistic effect between graphene and conducting polymers is responsible for this interesting result. The most widely used methodologies for the synthesis of these materials are still based on chemical routes. However, electrochemical routes have emerged and are gaining space, affording advantages such as low cost and the promising possibility of modulation of the structural characteristics of composites. As a result, application in sensor devices can lead to increased sensitivity and decreased analysis cost. Thus, this review presents the main aspects for the construction of nanomaterials based on graphene oxide and conducting polymers, as well as the recent efforts made to apply this methodology in the development of sensors and biosensors.

Equine bone blocks have osteogenic effects promoting bone regeneration with biocompatibility and osteoconductivity capacity. Human dental pulp stem cells (hDPSCs) can differentiate into osteoblasts enhancing biomineralization with such scaffolds. Melatonin is able to improve bone health and mediate bone formation. Collagenated equine bone blocks were coated with ammonia-functionalized graphene-oxide (G-N) at two different concentrations (2 μg/mL, G-N2; and 10 μg/mL, G-N10). The homogeneity of G-N coating was checked by Raman spectroscopy, whereas thermogravimetric analysis (TGA) allowed us to quantify the amount of G-N deposited on the blocks. The aim of this study was to investigate in vitro the effect of G-N-coated collagenated equine bone blocks on the proliferation and differentiation of hDPSCs with the addition of a melatonin. This evaluation was determined after 7, 14, and 21 days of culture by the expression of specific microRNAs, RUNX2 and SMAD5 gene expression, osteocalcin levels, and histological analysis. The results showed that equine blocks G-N2 and G-N10 and melatonin gave an optimal cell adhesion as shown by histological analysis, and an increase in the hDPSCs osteogenic potential as confirmed by microRNA and gene expression with an increase in osteocalcin levels. This study suggests that equine bone blocks coated with G-N2 and G-N10 and melatonin promote the osteogenic process.

Molecular dynamics (MD) simulations were carried out to study the physical properties of graphene-oxide (GO) and polydimethylsiloxane (PDMS) interfacial systems. Simulations were performed for GO molecules dispersed into short-chain, long-chain, and long-chain and cross-linked PDMS polymers. Various structural properties, dipole moments and dielectric constants of the graphene-oxide molecules were calculated, which were correlated with the electron transport properties of the GO/PDMS system. The effects of polymer length and type of linkage on transport properties were also examined. Image 1 [ABSTRACT FROM AUTHOR]

Palladium nanoparticles immobilized on Schiff base‐functionalized graphene‐oxide (GO−Pd) has been synthesized and characterized by FT‐IR, Raman, PXRD, UV‐Visible, TGA, XPS, FE‐SEM, TEM, EDAX, Elemental mapping, BET, AAS and ICP MS analysis. The GO−Pd showed promising catalytic activity for the Suzuki‐Miyaura, Hiyama and Heck‐Mizoroki coupling reactions with higher yields (up to 95%). GO−Pd can be easily filtered out from the reaction mixture and reused up to six times without significant loss of catalytic activity. All of the synthetic products obtained were fully characterized from their spectral data. [ABSTRACT FROM AUTHOR]

Nowadays, putting forward an accurate cancer therapy method with minimal side effects is an important topic of research. Nanostructures, for their ability in controlled and targeted drug release on specific cells, are critical materials in this field. In this study, a pH‐sensitive graphene oxide‐l‐arginine nanogel was synthesized to carry and release 5‐fluorouracil. Optimized conditions using statistical analysis, based on the maximum relative viscosity of nanogel, were evaluated: 5.489 for the concentration of l‐arginine and 2.404 for pH. The prepared nanogels were characterized using scanning electron microscope and transmission electron microscope images and Fourier‐transform infrared spectroscopic analysis. Cytotoxicity was assessed using the sulforhodamine B (SRB) assay on MCF‐7 breast cancer cells. The fluorouracil release was measured by the dialysis bag method, UV spectrophotometry, and fluorouracil calibration diagram. Results proved the successful controlled release of fluorouracil at pH 5.4 and the beneficial role of graphene‐oxide‐ l‐arginine‐ fluorouracil nanogel in eliminating cancer cells. [ABSTRACT FROM AUTHOR]

• Fabricating of a new shape memory polymer composites based on thermoplastic polyurethane (TPU) containing three types of graphinic particles: graphene oxide (GO) and reduced graphene oxide (rGO) and hybrid GO:rGO. • Evaluation of localization of GO and rGO particles into soft and hard segments of TPU matrix. • Tailoring a bridge between microstructure and macro-properties of TPU composites comprising 1, 2 and 5 wt% filler concentration. • Characterization of heat actuating of TPU composites with DMTA instrument. • Using of hybrid GO:rGO particles into the shape memory of TPU and find superior mechanical strength, the excellent shape fixity and high actuation value. We fabricated shape memory composites based on thermoplastic polyurethane (TPU) containing three types of graphene, that is, graphene-oxide (GO), reduced graphene-oxide (rGO) and hybrid GO:rGO (ratio 1:1) to study their mechanical and shape memory properties. Tailoring a bridge between microstructure and macro-properties of TPU composites comprising 1, 2 and 5 wt% filler concentration was the primary aim of this work. Incorporation of GO and rGO platelets into the TPU matrix augmented the modulus, elongation at break and breaking stress compared to that of pristine TPU. Besides, the TPU/rGO composites revealed greater young modulus, %elongation, storage modulus, and %crystallinity compared to TPU/GO composites at similar filler content. In particular, the TPU/GO:rGO composites displayed the synergic improvement in dynamic and static mechanical properties owing to the systematic localization GO and rGO platelets in hard and soft segments of TPU, respectively. Interestingly, this localization was thermodynamically predicted by the solubility parameter of components and approved with microscopic observation. The TPU composite behavior was further examined by relaxation stress analysis. While the GO platelets have no significant influence on shape recovery behavior as compared to rGO filled composites, on the other hand, the shape fixation is deteriorated by adding the rGO platelets. The shape memory assessment clarified that the simple TPU composites comprising GO(2 wt%) and rGO(5 wt%) have the highest value in shape fixity and shape recovery, respectively. Noteworthy, both shape fixity and recovery of TPU composites improved when simultaneously using the rGO and GO platelets (GO:rGO) as hybrid filler. The shape recovery and fixity value of 5 wt% TPU composite containing hybrid GO:rGO is 96.7% and 99.1%, respectively, which it has increased up 1.12, 1.05 and 1.02-fold in shape recovery that of neat TPU, 5 wt% TPU composite containing GO and rGO, respectively. This study proves that incorporation of hybrid GO:rGO into shape memory TPU matrix can be employed effectively to attain superior mechanical strength, the excellent shape fixity and high actuation value. [ABSTRACT FROM AUTHOR]

Abstract Accumulative Roll Bonding (ARB) was used to fabricate Graphene Oxide-reinforced Al-matrix composites. Graphene Oxide reinforcement was suspended in a stabilized aqueous solution and applied, prior to each ARB cycle, through airgun spraying. Different concentrations (graphene oxide/milipore water) were used and for each concentration, samples produced have undergone up to 5 rolling cycles. Optical and electron scanning microscopies were used for microstructural characterization which revealed a non-homogenous deformation of the layers across the composite's thickness. Although the presence of graphene-oxide promoted an increase in the microhardness, higher values were obtained with its lowest concentration for similar samples. The number of ARB cycles and the direction of the tested sections also influenced the microhardness results since the 5-cycle samples and the rolling direction sections for all the samples achieved higher hardness results. Graphene Oxide revealed to be a major contributor to the increase of stiffness during bending of the tested samples. [ABSTRACT FROM AUTHOR]