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In this paper, two relaxed CQ algorithms with non-inertial and inertial steps are proposed for solving the split feasibility problems with multiple output sets (SFPMOS) in infinite-dimensional real Hilbert spaces. The step size is determined dynamically without requiring prior information about the operator norm. Furthermore, the proposed algorithms are proven to converge strongly to the minimum-norm solution of the SFPMOS. Some applications of our main results regarding the solution of the split feasibility problem are presented. Finally, we give two numerical examples to illustrate the efficiency and implementation of our algorithms in comparison with existing algorithms in the literature. [ABSTRACT FROM AUTHOR]

The research community has witnessed an exceptional increase in exploring graphene related two-dimensional materials (GR2Ms) in many innovative applications and emerging technologies. However, simple, low-cost, sustainable, and eco-friendly methods to manufacture large quantities and high-quality GR2Ms still remain an unsolved challenge. To address limitations of conventional wet chemical-based exfoliation methods using graphite resources, the top-down irradiation approach has proven to be an ultrafast, effective, and environmentally friendly technology for scalable exfoliation, production, and processing of GR2Ms providing new properties for emerging applications. Significant advancements have been made for preparation of broad range of GR2Ms from graphite, such as graphene, graphene oxide, and reduced graphene oxide, and their doped, functionalized and modified forms over the past two decades, thanks to the availability of photon and ion irradiation techniques, such as microwave, infrared, ultraviolet, solar, x-ray, gamma, laser, and plasma. This review presents recent advances on the application of these various irradiation techniques and highlights their mechanism, differences in properties of prepared GR2Ms, and their advantages and disadvantages in comparison with other conventional methods. The review provides an insight into the irradiation strategies and their prospective applications to produce, at a large scale, low-cost, high-quality GR2Ms for practical applications in transparent electrodes, optoelectronic devices, sensors, supercapacitors, protective coatings, conductive inks, and composites. [ABSTRACT FROM AUTHOR]

We report a flexible and highly efficient wideband slot antenna based on a highly conductive composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and N-doped reduced graphene oxide (N-doped rGO) for wearable applications. The high conductivity of this hybrid material with low sheet resistance of 0.56 Ω/square, substantial thickness of 55 μm, and excellent mechanical resilience (<5.5% resistance change after 1000 bending cycles) confirmed this composite to be a suitable antenna conductor. The antenna achieved an estimated conduction efficiency close to 80% over a bandwidth from 3 to 8 GHz. Moreover, the successful operation of a realized antenna prototype has been demonstrated in free space and as part of a wearable camera system. The read range of the system was measured to be 271.2 m, which is 23 m longer than that of the original monopole antennas provided by the supplier. The synergistic effects between the dual conjugated structures of N-doped rGO and PEDOT in a single composite with fine distribution and interfacial interactions are critical to the demonstrated material performance. The N-doped rGO sheet reinforces the mechanical stability whereas the PEDOT functions as additive and/or binder, leading to an improved electrical and mechanical performance compared to that of the graphene and PEDOT alone. This high-performing nanocomposite material meets requirements for antenna design and opens the door for diverse future non-metallic flexible electronic device developments. [ABSTRACT FROM AUTHOR]

The valorization of onion-like carbon nanoparticles (OCNPs) from pollutant soot collected from diesel engine exhaust could be a promising and sustainable approach to develop percolated conductive networks in a poly(lactic acid) (PLA) matrix, which could be used for the design of conductive polymer nanocomposite (CPC)-based quantum resistive sensors (QRS). The aim of the present study is to incorporate these waste materials in the field of structural health monitoring (SHM) of biocomposites. Here, OCNPs have been used in the formulation of QRS and further integrated into unidirectional flax fibers and PLA composites for SHM trials without altering their mechanical properties. QRS transducers made of 1 wt% OCNPs dispersed into a PLA matrix have been prepared via an in situ spray layer-by-layer (sLbL) process during the fabrication of flax–PLA composites by film stacking under vacuum conditions. Their in situ sensing of strain and damage was evaluated by submitting the flax–PLA unidirectional composite samples to various incremental and simultaneous loading–unloading cycles. Most importantly, the piezo-resistive behavior of the OCNP-based QRS has been found to be reproducible, and it exhibits large-amplitude signals with a gauge factor of 6 ± 2, which is two to three times larger than that of commercial strain sensors. Additionally, these waste-derived OCNPs possess interesting ferromagnetic properties at room temperature. [ABSTRACT FROM AUTHOR]

The development of low-cost and high performing hydrogen gas sensors is important across many sectors, including mining, energy and defense using hydrogen (H 2) gas. Herein, we demonstrate a new concept of H 2 sensors based on Pd/Cr nanogaps created by using a simple mechanical bending deformation technique. These nanogap sensors can selectively detect the H 2 gas based on transduction of the volume expansion after H 2 uptake into an electrical signal by palladium-based metal-hydrides that allows closure of nanogaps for electrons flowing or tunneling. While this break-junction architecture, according to literature, can provide several advantages with research gaps in terms of fabricating nanogap sensors with ultra-fast response (≤4 s), the size of nanogap (≤20 nm) and their relationship with time response and recovery as addressed in this paper. Based on the computational modelling outcome, the size of the nanogaps can be investigated in order to optimize the fabrication conditions. Indeed, a single nanogap with optimum width (15 nm) acts as an on-off switch for best performing hydrogen detection. Moreover, with the unique design of Pd/Cr nanogap, the developed sensing device meets major requirement of advanced H 2 gas sensor including room temperature (25 °C) operation, detection of trace amounts (10–40,000 ppm), good linearity, ultra-fast response-recovery time (3/4.5 s) and high selectivity. The presented economical lithography-free fabrication method has simple circuitry, low power consumption, recyclability, and favorable aging properties that promises great potential to be used for many practical applications of H 2 detection. Image 1 • Fabrication and sensing performances of Pd/Cr nanogap hydrogen gas sensors is presented. • Fabrication is performed by single step bending deformation process. • Computational modelling confirms the optimal deformation conditions and gap of 15 nm. • High hydrogen sensitivity in range of 10–40,000 ppm and response time of 3–4 s is confirmed achieved. [ABSTRACT FROM AUTHOR]

The paper presents the tuning of sensitivity and selectivity performance of volatile organic compounds (VOCs) chemoresistive sensors for biomarker detection using the hybridization of pristine graphene (pG) and metal organic frameworks (MOFs). The synergistic effect of this nanocomposite material was discovered showing improved sensing performances where graphene acts as a highly conductive sensing element, and MOFs, with a high surface area and adsorption capacity provide an enhanced sensitivity and selectivity for specific VOCs. By combining and selecting different MOFs, we proposed that is possible to tailor sensing performances of chemoresistive sensors for VOC biomarkers detection. To prove that graphene hybrid nanocomposite with selected MOFs including copper–benzene-1,3,5-tricarboxylate (pG-Cu BTC), zirconium 1,4-dicarboxybenzene (pG-UiO 66) and 2-methylimidazole zinc salt (pG-ZIF 8), were investigated to enhance the sensing performance and capability of distinguishing different VOC biomarkers (e.g., methanol, ethanol, chloroform, acetone, acetonitrile and THF). Results showed that the pG-Cu BTC sensor has the highest sensitivity and selectivity towards chloroform and methanol VOCs at 2.82–22.6 ppm level. The proposed concept presents a valuable contribution for the development of low-cost and high-performing VOC biomarker sensors for monitoring human health from metabolic human breath and further implementation for non-invasive biomedical diagnostics for personalized telehealth monitoring. Image 10660 [ABSTRACT FROM AUTHOR]

One of the most studied photoluminescence emission peaks of anatase titanium dioxide (TiO 2) is green, located at about 520 nm, which is assigned to the radiative recombination between a mobile electron in the conduction band and oxygen vacancy defect as a trapped hole in the bandgap. Composite materials of TiO 2 with graphene are normally shown by the gradual quenching of photoluminescence intensity as a result of carrier lifetime extension, which is important to enhance photocatalytic activity. Herein we report an observation of the intensity enhancement of the green PL emission in a composite TiO 2 nanotube (TNT) and graphene produced through facile hydrothermal synthesis. The heterojunction formation of graphene and TNT makes the excited photoelectrons easy to diffuse from TNT to graphene. Hence, the recombination rate of mobile electrons in graphene and trapped holes located on the nanotube surface is enhanced due to the high mobility of electrons in graphene. • A facial hydrothermal systhesis of titanium dioxide nanotube (TNT) and graphene composite. • The nanohybridization formation between graphene and TNT was revealed by XRD and Raman shift. • The intensity of the green photoluminescence emission at 530 nm was considerably increased in the composite. • The electromigration between graphene and TNT is a reason for the high green emission intensity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Magnetic iron oxide nanoparticles decorated graphene gas sensor is presented. • The accurate particle size synthesis was conducted by using poly(ion liquids) (PIL). • The influence of particle size on sensitivity was evaluated. • Particles of a size of 20 nm have a significant enhancement of sensitivity. • The graphene-Fe 3 O 4 sensor detect trace amounts (1 ppm) of the NO 2 and ethanol. Abstract We report a synthesis of magnetic nanoparticles chemically immobilized onto reduced graphene oxide sheets (referred to as rGO-Fe 3 O 4 NPs) as a gas and vapor sensing platform with precisely designed particle size of 5, 10 and 20 nm to explore their influence of particle size on sensing performance. The rGO-Fe 3 O 4 NP sensors have been investigated their responses to different gases and volatile organic compounds (VOCs) at part-per-million (ppm) levels. Results show that the Fe 3 O 4 NPs with smaller size (5 and 10 nm) on the rGO surface led to a lower sensitivity, while particles of a size of 20 nm have a significant enhancement of sensitivity compared to the bare rGO sensor. The rGO-Fe 3 O 4 NP20 sensor can detect trace amounts of NO 2 gas and ethanol vapor at the 1 ppm and is highly selective to the NO 2 and ethanol among other tested gases and VOCs, respectively. The particle size causes different distribution behaviour of NPs over rGO surface and interspaced between them, which results in deceased or increased the surface interactions between gas and graphene. The NPs themselves contained different defects level and the charge depletion layer that affect their adsorption gas/vapor molecules, which are explained for different sensing responses. [ABSTRACT FROM AUTHOR]

We report a new method for the fabrication of highly conductive and transparent ultrathin nitrogen (N) doped graphene films from graphene inks by combining a microwave treatment, ultrasonic nebulizer coating and thermal annealing. The starting graphene oxide (GO) solution was mixed with poly(ionic liquids) (PIL) and treated with microwave (Mw) irradiation to prepare Mw-rGO@PIL inks, which is a gentle reduction of PIL-attached reduced graphene oxide (rGO). In this non-contacting heating method, the PIL was used to not only mediate microwave irradiation and prevent disorder of the graphitic structure, but also repair the lattice defects and introduce nitrogen into the graphitic structure. The ultra-thin graphene films were prepared using the nebulizer for controlling the aerosol droplet distribution of the Mw-rGO@PIL inks coated onto quartz or glass substrates. The prepared films displayed a surface resistance of ∼1.45 × 10 7  Ω/sq at a transparency of ∼87%. A further thermal treatment was conducted to improve the conductivity of the prepared films by annealing at a high temperature (900 °C), which allowed complete reduction of oxygen containing groups, enhanced graphitization, and reordering of the basal graphene plane and N-doping of the carbon lattice (pyrolytic PIL). The resulting thin films significantly reduced the surface resistance in the range of 1.5 × 10 3 to 6.2 × 10 3  Ω/sq at a transparency ranging from 68 to 82%, respectively. The presented method involving in situ N-doping offers a promising environmentally-friendly, low-cost and scalable manufacture of high-quality conductive N-doped graphene films. [ABSTRACT FROM AUTHOR]

Development of next-generation sensor devices is gaining tremendous attention in both academia and industry because of their broad applications in manufacturing processes, food and environment control, medicine, disease diagnostics, security and defense, aerospace, and so forth. Current challenges include the development of low-cost, ultrahigh, and user-friendly sensors, which have high selectivity, fast response and recovery times, and small dimensions. The critical demands of these new sensors are typically associated with advanced nanoscale sensing materials. Among them, graphene and its derivatives have demonstrated the ideal properties to overcome these challenges and have merged as one of the most popular sensing platforms for diverse applications. A broad range of graphene assemblies with different architectures, morphologies, and scales (from nano-, micro-, to macrosize) have been explored in recent years for designing new high-performing sensing devices. Herein, this study presents and discusses recent advances in synthesis strategies of assembled graphene-based superstructures of 1D, 2D, and 3D macroscopic shapes in the forms of fibers, thin films, and foams/aerogels. The fabricated state-of-the-art applications of these materials in gas and vapor, biomedical, piezoresistive strain and pressure, heavy metal ion, and temperature sensors are also systematically reviewed and discussed, and their sensing performance is compared. [ABSTRACT FROM AUTHOR]

Abstract: Quantum chemo-resistive vapour sensors have been synthesised from the assembly of magnetic nanoparticles-decorated reduced graphene oxide (Fe3O4–RGO) with poly(3,4-ethylene dioxythiophene) (PEDOT) and poly(ionic liquid) (PIL). This new hybrid sensing material demonstrated enhanced sensitivity, selectivity, signal-to-noise ratio and reduced response time compared to its elementary constituents (also sensitive), which suggests that a positive synergy of properties has been reached through the structuring of the conducting architecture by spray layer-by-layer. The Fe3O4-RGO/PIL–PEDOT sensor exhibited stable and reproducible signals at room temperature for both polar (ethanol, methanol, acetone, water) and non-polar (chloroform, styrene, dichlorobenzene, toluene) volatile organic compounds (VOC), considered as food degradation biomarkers. Since sensor’s responses are still well defined at the ppm level (and may be even at the subppm level) as attested by a SNR around 10, an application such smart packaging could be envisaged. [Copyright &y& Elsevier]

Highlights: [•] Hybrid film of RG-O and PEDOT was prepared using vapor-phase-polymerization method. [•] PIL was used as a template for PEDOT growth and bridging RG-O and PEDOT. [•] Hybrid film-based sensors are capable of detecting a trace level of different VOCs. [Copyright &y& Elsevier]

The membrane phospholipid phosphatidylserine is exposed on the cell surface during apoptosis and acts as an eat-me signal in the phagocytosis of apoptotic cells in mammals and nematodes. However, whether this is also true in insects was unclear. When milk fat globule-epidermal growth factor 8, a phosphatidylserine-binding protein of mammals, was ectopically expressed in Drosophila, the level of phagocytosis was reduced, whereas this was not the case for the same protein lacking a domain responsible for the binding to phosphatidylserine. We found that the extracellular region of Draper, an engulfment receptor of Drosophila, binds to phosphatidylserine in an enzyme-linked immunosorbent assay-like solid-phase assay and in an assay for surface plasmon resonance. A portion of Draper containing domains EMI and NIM located close to the N-terminus was required for binding to phosphatidylserine, and a Draper protein lacking this region was not active in Drosophila. Finally, the level of tyrosine-phosphorylated Draper, indicative of the activation of Draper, in a hemocyte-derived cell line was increased after treatment with phosphatidylserine-containing liposome. These results indicated that phosphatidylserine serves as an eat-me signal in the phagocytic removal of apoptotic cells in Drosophila and that Draper is a phosphatidylserine-binding receptor for phagocytosis. [ABSTRACT FROM AUTHOR]

Hybrid materials of Fe3O4-decorated reduced graphene oxide (Fe3O4-RGO) and poly(3,4-ethylenedioxythiophene) (PEDOT) were prepared by poly(ionic liquid)-mediated hybridization. In this hybrid material, poly(ionic liquid) was found to perform multiple roles for: (1) stabilizing Fe3O4-RGO against aggregation in the reaction medium, (2) transferring Fe3O4-RGO nanomaterials from aqueous into organic phase, and (3) associating Fe3O4-RGO nanomaterials with PEDOT. The hybrid materials of Fe3O4-RGO with PEDOT showed the lowest surface resistivity of 80 Ω sq−1 at an RGO-Fe3O4 loading of 1 wt %, and exhibited superparamagnetic behavior with an electromagnetic interference shielding effectiveness of 22 dB. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

Abstract: Hybrid materials of reduced graphene oxide (RG-O) and poly(3,4-ethylenedioxythiophene) (PEDOT) were prepared by poly(ionic liquid)-mediated hybridization. In this hybrid material, poly(ionic liquid)s (PILs) are found to be preferentially physisorbed onto the RG-O platelets, and allow them to be dispersed as a homogeneous colloidal system. In addition to the function as an effective stabilizer, the PIL also promotes PEDOT growth on RG-O platelets through favorable molecular interaction of PIL with PEDOT chains. The resulting material, a hybrid of RG-O and PEDOT showed an electrical conductivity of 18.8S/cm at a RG-O loading of 0.3wt.%, and its thin film on glass substrate showed a surface resistivity as low as 1.8×104 Ω/sq at an optical transmittance of 91.18%. [Copyright &y& Elsevier]

Abstract: We report a conductive hybrid material composed of single-walled carbon nanotubes (SWCNTs) and poly(3,4-ethylenedioxythiophene) (PEDOT). The hybridization of SWCNT and PEDOT was achieved by the use of poly(ionic liquid) (PIL), specifically poly(1-vinyl-3-ethylimidazolium) salt as the bridging molecules between the two conductive components. The use of PIL not only allows the formation of effective 3D network of SWCNT bundles in the PEDOT matrix, but also enables the resulting SWCNT-PIL:PEDOT hybrid material to be suspended selectively in water or organic solvents. Thin films of SWCNT-PIL:PEDOT were more conductive as compared to the PEDOT-based films, demonstrating the surface resistivity of 6.2×104 Ω/sq and optical transparency of 85.5% at a 0.2wt.% SWCNT loading. The composites were also found to be thermally stable, showing less change in surface resistivity as compared to PEDOT-based films. [Copyright &y& Elsevier]

Abstract: We report a procedure to prepare a conducting nano-composites composed of multi-walled carbon nanotubes (MWNTs) and PEDOT by using a poly(sodium 4-styrenesulfonate) (PSSNa) as a inter-linking molecule between MWNT and PEDOT. When PSSNa chains are introduced on the MWNTs via physicochemical interaction, the surface of MWNT becomes negatively charged, and PSS-modified MWNTs promote the effective association of the positively charged PEDOT chains. The resulting MWNT-PSS/PEDOT composites are characterized by a better interconnection between MWNT and PEDOT components. [Copyright &y& Elsevier]

Abstract: The paper introduces some results on stability of sheaf-solutions, exponential stability of solutions and sheaf-solutions of set differential equations and their applications to set control differential equations. [Copyright &y& Elsevier]

Abstract: In this paper, we study the existence and some properties of solutions of the so-called set control differential equations (SCDE) and sheaf-solutions of sheaf set control problems. [Copyright &y& Elsevier]

Nitrogen-doped carbon hybridized nanodiamond (N-doped C@ND) materials have been developed and used as an electrocatalytic for oxygen reduction reactions (ORRs). The polymerized ionic liquids are employed to modify NDs and then subjected to thermal annealing at 600 °C, resulting in a high concentration of N-doped (9.33 at.%) carbon frameworks attached on the ND surface. This N-doped C@ND material provides a highly active mesoporous structure (4 nm pore) with a high surface area (366 m2 g−1) and allows for enhancement of catalytic performance compared to pure NDs. The N-doped C layers altered the electroneutrality of NDs, creating favourable charged sites for oxygen adsorption, thus weakening the O–O bond strength to facilitate ORR activity. Having a predominant four-electron transfer pathway with a total electron transfer number of 3.44–3.88 in the potential region of 0.1–0.8 VRHF, the N-doped C@ND-based catalyst materials performed well as a catalyst for the ORR in the alkaline medium. This affordable material and simple process will find potential application in clean energy generation and storage, durable fuel cells and metal–air batteries. [ABSTRACT FROM AUTHOR]

The use of pristine graphene (pG) based on solution processed coating technologies is often limited by their poor dispersibility in water and organic solvents which prevents to achieve the best performing properties of pG in coating applications. To address these limitations, we developed a dispersant-free coating approach of pG based on their intrinsic solid-lubricity and interlayer electrostatic interactions. The “rotating drum” method was established to provide suitable conditions for electrostatic deposition of pG-powder which is demonstrated on two model substrates with granular and fibril morphologies (urea and acrylic fibers) to improve their physical and electrical properties. The results showed that the pG coating enables to minimize moisture induced caking tendency of commercial urea prills at a relative humidity (RH) of 85% (higher than critical humidity) exhibiting greater moisture rejection ability (∼2 times higher than uncoated urea) and to improve their anti-abrasive properties. The pG-powder coating applied on nonconductive acrylic fibers provides a stable conductive layer (∼0.8 ± 0.1 kΩ/sq) which made them suitable for using in wearable electronics, sensors and electromagnetic interference (EMI) shielding. The developed coating method for pG-powder based on “rotating drum” is generic, simple, eco-friendly, low-cost, and scalable for broad range of coating applications. [ABSTRACT FROM AUTHOR]

A correction to the article "Electromagnetic properties of Fe3O4-Functionalized Graphene and Its Composites with a Conducting Polymer," that was published online on June 5, 2013 issue is presented.

Iron oxide nanoparticles have been extensively used for energy production in fuel cells; however, the different phases of iron oxide have not been adequately investigated for their effect on the oxygen reduction reaction (ORR). The low temperature synthesis of four kinds of iron oxide nanoparticles with different phases was incorporated inside 3D reduced graphene oxide (rGO) aerogels and their electrochemical, catalytic and electron transfer properties were determined for ORR. The results showed that, at low potentials (0.20 V), rGO composites containing magnetite, maghemite and goethite catalyse ORR via four-electron transfer kinetics while hematite facilitated two-electron transfer kinetics. At higher potentials (0.70 V), all four catalysts proceeded via a two-electron pathway. [ABSTRACT FROM AUTHOR]

Carbon nanodots (CNDs) derived from a green precursor, kidney beans, was synthesized with high yield via a facile pyrolysis technique. The CND material was easily modified through simple oxidative treatment with nitric acid, leading to a high density “self-passivated” water soluble form (wsCNDs). The synthesized wsCNDs have been extensively characterized by using various microscopic and spectroscopic techniques and were crystalline in nature. The highly carboxylated wsCNDs possessed tunable-photoluminescence emission behavior throughout the visible region of the spectrum, demonstrating their application for multicolor cellular imaging of HeLa cells. The tunable-photoluminescence properties of “self-passivated” wsCNDs make them a promising candidate as a probe in biological cell-imaging applications. [ABSTRACT FROM AUTHOR]

Herein, the visible light‐photocatalytic performance of synthesized ZnO/Gr composite materials with different Gr content under various conditions, i.e., pH, dye concentration, and different scavengers (to understand the photocatalytic activity mechanism) is systematically investigated. Photocatalytic performance is evaluated with the degradation of methylene blue (MB) in solution under sunlight irradiation. The presence of graphene (Gr) in the ZnO/Gr composites shows enhanced photocatalytic activity compared to pure ZnO under natural sunlight illumination. The highest photodegradation efficiency of ≈94% when the content of Gr is 1 wt% in comparison to ≈76% for the pure ZnO, corresponding to reaction rate constants of 0.01038 and 0.00615 min−1, respectively. Compared to recent publications, the degradation efficiency is high with relatively high dye concentration, low catalyst amount, and large solution volume. The enhanced visible light absorption and the reduction of bandgap value are attributed to the enhanced photocatalytic properties of the hybridized composite. Moreover, the investigation of the effect of scavenger substances shows that H2O2 strongly enhanced their photocatalytic ability, suggesting that holes (h+) contribute as the reactive agent in the photodegradation process. [ABSTRACT FROM AUTHOR]

Abstract: The existence and comparison results on solutions of set control differential equation were studied in [N.D. Phu, T.T. Tung, Some results on sheaf-solutions of sheaf set control problems, Nonlinear Analysis 67 (2007) 1309–1315]. In this paper, we present the stability criteria for solutions of set control differential equation. [Copyright &y& Elsevier]

Functionalization of pristine graphene to achieve high water dispersibility remains as a key obstacle owing to the high hydrophobicity and absence of reactive functional groups on the graphene surface. Herein, a green and simple modification approach to prepare highly dispersible functionalized graphene via thermal thiol-ene click reaction was successfully demonstrated on pristine graphene. Specific chemical functionalities (–COO, –NH2 and –S) on the thiol precursor (L-cysteine ethyl ester) were clicked directly on the sp2 carbon of graphene framework with grafting density of 1 unit L-cysteine per 113 carbon atoms on graphene. This functionalized graphene was confirmed with high atomic content of S (4.79 at % S) as well as the presence of C–S–C and N–H species on the L-cysteine functionalized graphene (FG-CYS). Raman spectroscopy evidently corroborated the modification of graphene to FG-CYS with an increased intensity ratio of D and G band, ID/IG ratio (0.3 to 0.7), full-width at half-maximum of G band, FWHM [G] (20.3 to 35.5) and FWHM [2D] (64.8 to 90.1). The use of ethanol as the reaction solvent instead of common organic solvents minimizes the chemical hazards exposure to humans and the environment. This direct attachment of multifunctional groups on the surface of pristine graphene is highly demanded for graphene ink formulations, coatings, adsorbents, sensors and supercapacitor applications. [ABSTRACT FROM AUTHOR]

The absence of rapid, reliable and cost-effective quality control for industrially manufactured graphene materials is an immediate problem for the emerging graphene industry. Recent studies have alarmingly revealed that a large percentage of manufactured graphene materials traded worldwide have a large variation of properties, and some of them are overpriced graphite powders. Currently, benchmark graphene characterization methods based on localized analysis can provide information of key properties of graphene such as the number of layers, particle size, and defects, only on individual graphene particles, which do not represent the properties of "bulk" material. To address these limitations, we developed and validated thermogravimetric analysis (TGA) as a simple analytical tool for characterization and quality control of manufactured few-layer graphene (FLG) and their non-graphene impurities in powder forms. Our results, using verified control and industrial samples, revealed that the derivative TGA graphs of FLG, graphene oxide and graphite powders have signatory distinctive peaks with temperature of maximum mass decomposition rates (T max) in specific ranges, reflecting differences of their structural, chemical, and thermal properties, which are suitable for their qualitative and quantitative analysis. The method is applicable for graphene manufacturers and end-users for simple, low-cost and reliable quality control of graphene materials that will not fail to detect "fake" graphene. [Display omitted] • A TGA method for quality control of graphene powders is introduced and validated. • Method allows quantitative and qualitative analysis of non-graphene components in graphene. • Number DTG peaks, their position and area are identified as key analytical parameters. • It is recommended as simple low-cost and reliable method to detect "fake graphene". [ABSTRACT FROM AUTHOR]

The coexistence of multiple toxic water pollutants (heavy metals, organic dyes, oils, and organic solvents) limits the sustainable supply of clean water worldwide and urges the development of advanced water purification technology that can remove these contaminants simultaneously. Since its discovery, graphene‐based materials have gained substantial attention toward development of new‐generation sorbents for water purification. Despite several recently published reviews on water purification technology using graphene and its derivatives, there is still a gap in the review considering multiple water‐pollutant remediation using advanced graphene materials. In this review, in the first instance, a comparative structure–function–performance relationship between graphene‐based sorbents and the multipollutants in water is established. A fundamental correlation is made between the sorption performance for diverse pollutants in water with the more specific adsorption properties (surface area, pore size, type of functional groups, C/O, C/N, and C/S atomic ratio) of advanced graphene sorbents. Second, the underlying interaction mechanisms are uncovered between different classes of water pollutants using single graphene‐based sorbents. Third, the rational design of advanced multipollutant sorbents based on graphene is elaborated. The reality, challenges, and opportunities of advanced graphene materials as emerging sorbents for sustainable water purification technology are finally presented in the last section. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis of bio-graphene foams (bGFs) from renewable sources, and the application of bGFs as new adsorbents in removal of chromate ions and oil contaminants from waste water. A two-step synthetic method was developed to produce bGFs with unique porous architecture and high specific surface area (up to 805 m2 g−1) that is highly desirable for environmental applications. The adsorption performance of prepared bGFs for removal of chromate ions from water was studied in relation to CrO 4 2− concentration, adsorbent load, pH, and contact time to confirm adsorption capacity, kinetics and pH dependence. The adsorption isotherms of chromate ions were consistent with the Langmuir model, revealing an outstanding adsorption capacity of 245 mg of Cr(VI)/g bGFs (pH∼7). bGFs were capable of reducing Cr(VI) in water below the maximum permissible level (0.050 mg dm−3) for human consumption (WHO). In a second application, our results convincingly showed excellent performance of bGFs in separating organic solvents and oils from water in a continuous oil-water separation process showing 99.1% and 98.8% separation efficiency for toluene and petroleum, respectively. Our findings confirm that the outstanding performance of bGFs, and suggest their use as efficient adsorbents for environmental remediation. • Synthesis of bio-graphene foams (bGFs) from a mixture of glucose, citric acid, urea, and graphene oxide. • The developed bGFs processes unique porous architecture and high specific surface area. • The bGFs use as a new adsorbent for the removal of chromate ions and oil contaminants from waste waters. • The developed materials show an outstandingly high adsorption capacity of 245 mg of Cr(VI)/g at neutral pH. • Outstanding performance for continuous oil-water separation efficiency for toluene (99%) and petroleum (98.8%). [ABSTRACT FROM AUTHOR]

Macroporous carbon materials (MCMs) are used extensively for many electrocatalytic applications, particularly as catalysts for oxygen reduction reactions (ORRs)—for example, in fuel cells. However, complex processes are currently required for synthesis of MCMs. We present a rapid and facile synthetic approach to produce tailored MCMs efficiently via pyrolysis of sulfonated aniline oligomers (SAOs). Thermal decomposition of SAO releases SO2 gas which acts as a blowing agent to form the macroporous structures. This process was used to synthesise three specifically tailored nitrogen (N)-doped MCM catalysts: N-SAO, N-SAO (phenol formaldehyde) (PF) and N-SAO-reduced graphene oxide (rGO). Analysis using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the formation of macropores (100–350 µm). Investigation of ORR efficacy showed that N-SAOPF performed with the highest onset potential of 0.98 V (vs. RHE) and N-SAOrGO showed the highest limiting current density of 7.89 mAcm−2. The macroporous structure and ORR efficacy of the MCM catalysts synthesised using this novel process suggest that this method can be used to streamline MCM production while enabling the formation of composite materials that can be tailored for greater efficiency in many applications. [ABSTRACT FROM AUTHOR]

A novel porous 3D-structured carbon composite material with a unique architecture by combining graphene and carbonized metal-organic framework (C-MOF) (HKUST-1) microrods for high performing supercapacitors has been synthesised and characterised. The HKUST-1 microrods were prepared by a new method, converting their diamond-like shape into microrods via mechanical shear mixing in an aqueous solution. Grinding of HKUST-1 and graphene oxide (GO) resulted in the formation of a 3D GO-MOF composite with intercalated HKUST-1 microrods between GO sheets. The composite film was treated by a laser scribing method and created a highly porous, a high surface area (>600 m2/g) and conductive 3D nanostructured composite film (L-rGO-C-MOF) used as electrodes for supercapacitor applications. The prepared film showed a high capacitance of 390 F/g at 5 mV/s, and a cyclic stability of 97.8% at 10 A/g after 5000 cycles. The symmetrical supercapacitor delivered an excellent power density of 8037.5 W/kg with an outstanding energy density of 22.3 Wh/kg confirming a new pathway to design new 3D porous graphene-MOF composites for high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

Rapid depletion of fossil fuel and increased energy demand has initiated a need for an alternative energy source to cater for the growing energy demand. Fuel cells are an enabling technology for the conversion of sustainable energy carriers (e.g., renewable hydrogen or bio-gas) into electrical power and heat. However, the hazardous raw materials and complicated experimental procedures used to produce electro-catalysts for the oxygen reduction reaction (ORR) in fuel cells has been a concern for the effective implementation of these catalysts. Therefore, environmentally friendly and low-cost oxygen reduction electro-catalysts synthesised from natural products are considered as an attractive alternative to currently used synthetic materials involving hazardous chemicals and waste. Herein, we describe a unique integrated oxygen reduction three-dimensional composite catalyst containing both nitrogen-doped carbon fibers (N-CF) and carbon microspheres (N-CMS) synthesised from apricot sap from an apricot tree. The synthesis was carried out via three-step process, including apricot sap resin preparation, hydrothermal treatment, and pyrolysis with a nitrogen precursor. The nitrogen-doped electro-catalysts synthesised were characterised by SEM, TEM, XRD, Raman, and BET techniques followed by electro-chemical testing for ORR catalysis activity. The obtained catalyst material shows high catalytic activity for ORR in the basic medium by facilitating the reaction via a four-electron transfer mechanism. [ABSTRACT FROM AUTHOR]

Point-of-care (POC) diagnostic technologies for early stage diagnosis and real-time monitoring of medical conditions are important element of healthcare strategy to improve medical treatment outcomes. Graphene, one-atom-thick fabric of carbon, has attracted enormous attention as a new sensing platform for the development of a new generation of nanoscale sensing devices. The two-dimensional (2D) nanostructure and high surface-to-volume ratio of graphene provide a strategy for designing sensing devices with capability to detect diverse analyte molecules. Their excellent conductivity and zero-band gap features promote electron transport between the sensor and analyte molecules, which is crucial for the development of ultra-fast-responsive and high sensitive devices for numerous biomedical applications. Particularly, owing to ease of fabrication and miniaturization, low cost, and simplicity of operation, graphene-based sensors offer a great potential for portable real-time medical diagnostics, when compared with conventional techniques based on expensive and labor extensive lab-bench instruments. This review provides a brief overview of recent progress in graphene-based sensors for the detection of volatile organic compounds (VOCs) and diagnosis of diseases via non-invasive analysis. Techniques for the fabrication of sensors and critical analysis of VOCs detection devices associated with various diseases are presented. We also summarized approaches to overcome the remaining obstacles in real-world applications of sensors in clinical diagnosis. [ABSTRACT FROM AUTHOR]

This paper is devoted to studying the maximal and minimal solutions for the interval-valued functional integrodifferential equations (IFIDEs) under generalized Hukuhara differentiability by the method of upper and lower solutions and monotone iterative technique. Some examples are given to illustrate the results. [ABSTRACT FROM AUTHOR]

In this work we investigate the crystal transformation and optical properties of hydrothermal titania nanotube (TNT) when combining with large size of exfoliated graphene achieved by electrochemical process (EC-Gr). The TNT monoclinic structure has been changed to TiO 2 anatase phase when TNT was grown in the presence of graphene dispersion. The effect of graphene on the evolution of TNT crystal could be understood by the interaction of carbon elements in graphene and Ti4+ ions in the titania structure. Due to the carrier separation which reduced recombination rate of excited photoelectrons and holes revealed by photoluminescence characterizations, the visible light photocatalytic activity in degradation of methylene blue in solution of the composite was enhanced. The photocatalytic enhancement was discussed and clarified based on UV–vis diffuse absorption spectra and time-resolved photoluminescence investigation. • The TNT@EC-Gr photocatalyst was successfully synthesized by a facile hydrothermal method. • TNT was transformed from monoclinic to anatase phase in nanocomposite. • MB dye degradation performance under sunlight was improved in nanocomposite. • Compositing with graphene reduced the band gap and prolonged the carriers' lifetime. • The bandgap diagram was proposed to elucidate the photocatalytic mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • A cell-laden antibacterial bioink based on Methylcellulose/Alginate was developed. • Possess high thixotropic behavior enabling the fabrication of complex 3D assemblies. • Gallium-crosslinked bioink exhibits potent antibacterial activity toward bacteria. • Gallium-crosslinked bioink supports the encapsulated fibroblast cellular functions. Bioink with inherent antibacterial activity is of particular interest for tissue engineering application due to the growing number of bacterial infections associated with impaired wound healing or bone implants. However, the development of cell-laden bioink with potent antibacterial activity while supporting tissue regeneration proved to be challenging. Here, we introduced a cell-laden antibacterial bioink based on Methylcellulose/Alginate (MC/Alg) hydrogel for skin tissue engineering via elimination of the risks associated with a bacterial infection. The key feature of the bioink is the use of gallium (Ga+3) in the design of bioink formulation with dual functions. First, Ga+3 stabilized the hydrogel bioink by the formation of ionic crosslinking with Alg chains. Second, the gallium-crosslinked bioink exhibited potent antibacterial activity toward both Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria with a bactericidal rate of 99.99 %. In addition, it was found that the developed bioink supported encapsulated fibroblast cellular functions. [ABSTRACT FROM AUTHOR]

Plasma electrolytic oxidation (PEO) is proven as a scalable method for surface treatment of titanium (Ti) providing a thick oxide layer with porous micro-nano morphology. Despite the lack of antibacterial performance, this modification has potential to improve the osseointegration properties of Ti-based implant. To address this limitation, we demonstrated a new concept, showing that partial incorporation of graphene oxide (GO) to porous-PEO Ti-surface can significantly improve its antibacterial performance. Our idea for partial coating compared with a full surface coverage of GO was motivated to create a mixed surface with porous PEO and GO to improve antibacterial ability, while maintaining the osseointegration properties. To achieve these goals, we combined PEO and electrophoretic deposition process (EPD) to deposit GO sheets over the titanium PEO-treated substrate. The SEM, EDS, optical profilometry, XRD and Raman spectroscopy confirmed the growth of unique multi-structured porous PEO structures decorated with GO patches. The bio-mineralization test provided the evidence of hydroxyapatite formation over the PEO-GO surface, indicating its good bioactivity. Finally, PEO-GO samples demonstrated a superior antibacterial rate of ~80% against E.coli and ~100% against S. aureus. These results indicate that PEO-GO modified titanium substrates are very promising for the development of advanced biomedical implants. Unlabelled Image • Plasma Electrolytic Oxidation (PEO) and Electrophoretic Deposition (ED) are combined for Graphene Oxide deposition (GO). • Partial deposition of (GO) sheets on PEO anodized titanium as new antibacterial surface is demonstrated. • The optimized deposition with 60% GO surface coverage is found as the best performing. • Antibacterial activity ~80% against E.coli and ~100% against S. aureus bacteria is achieved. [ABSTRACT FROM AUTHOR]

Well-defined sulfonated aniline oligomer (SAO) microstructures with rod and flake morphologies were successfully synthesized using an aniline and oxidant with a molar ratio of 10:1 in ethanol and acidic conditions (pH 4.8). The synthesized oligomers showed excellent dispersibility and assembled as well-defined structures in contrast to the shapeless aggregated material produced in a water medium. The synergistic effects among the monomer concentration, oxidant concentration, pH, and reaction medium are shown to be controlling parameters to generate SAO microstructures with distinct morphologies, whether micro sheets or micro rods. [ABSTRACT FROM AUTHOR]