Preparation and antibacterial activity of graphene oxide/cuprous oxide/zinc oxide nanocomposite

In this study, an antibacterial GO/Cu2O/ZnO nanocomposite was synthesized by a hydrothermal synthesis method, and its phase and microstructure were characterized by a series of test methods. The results showed that the synthesized cuprous oxide nanoparticals and the added zinc oxide nanoparticals were uniformly dispersed on the surface of graphene oxide, and did not cause the agglomeration of the nanoparticles. The graphene oxide successfully made enhanced the effective surface area of the metal oxide nanoparticles due to its adsorption capacity and chargeability. Thereby enhancing the antibacterial activity of the nanocomposite, reaching a 100% antibacterial rate.

ZnO Nano-Flowers Assembled on Carbon Fiber Textile for High-Performance Supercapacitor’s Electrode

Herein, a crystalline nano-flowers structured zinc oxide (ZnO) was directly grown on carbon fiber textile (CFT) substrate via a simple hydrothermal process and fabricated with a binder-free electrode (denoted as ZnO@CFT) for supercapacitor (SC) utilization. The ZnO@CFT electrode revealed a 201 F·g−1 specific capacitance at 1 A·g−1 with admirable stability of >90% maintained after 3000 cycles at 10 A·g−1. These impressive findings are responsible for the exceedingly open channels for well-organized and efficient diffusion of effective electrolytic conduction via ZnO and CFT. Consequently, accurate and consistent structural and morphological manufacturing engineering is well regarded when increasing electrode materials’ effective surface area and intrinsic electrical conduction capability. The crystalline structure of ZnO nano-flowers could pave the way for low-cost supercapacitors.

Plasma-Assisted Three-Dimensional Lightscribe Graphene as High Performance Supercapacitors

Graphene-based supercapacitors demonstrate extraordinary energy storage capacity due to their layered structure, large effective surface area, high electrical conductivity and acceptable chemical stability. Herein, reduced graphene oxide (rGO)-based supercapacitors were introduced in a simple, green, fast and inexpensive method. For this purpose, graphene oxide (GO) was synthesized by the modified Hummers’ method and then easily reduced to desired patterns of rGO using a commercial LightScribe DVD drive. In order to increase the effective surface area, as well as the electrical conductivity of rGO layers, oxygen/sulfur hexafluoride plasma was applied to the rGO followed by laser irradiation. By performing such sequential processes, an rGO-based supercapacitor was introduced with a capacitance of about 10.2 F/cm3, which had high stability for more than 1000 consecutive charge-discharge cycles. The fabrication steps of the electrodes were investigated by different analyses such as SEM, TEM, Raman, surface resistance and XPS measurements. Results show that these rGO-based electrodes fabricated by sequential processes are very interesting for practical applications of energy storage.

A Molecular Dynamics Study of Heat Transfer Enhancement during Phase Change from a Nanoengineered Solid Surface

This study investigates the enhancement of the rate of evaporation from a nanoengineered solid surface using non-equilibrium molecular dynamics simulation. Four different types of surface modifications were introduced to examine the thermal transportation behavior. The surface modification includes: (1) transformation of surface wetting condition from hydrophobic to hydrophilic, (2) implementing nanostructures on the smooth surface, (3) cutting nano slots on the smooth surface and (4) introducing nano-level surface roughness. Evaporation behavior from the same effective surface area was also studied. The simulation domain consisted of three distinct zones: solid base wall made of copper, a few layers of liquid argon, and a vapor zone made of argon. All the nano-level surface modifications were introduced on the solid base surface. The few layers of liquid argon representing the liquid zone of the domain take heat from the solid surface and get evaporated. Outside this solid and liquid zone, there is argon vapor. The simulation began at the initial time t = 0 ns and then was allowed to reach equilibrium. Immediately after equilibrium was achieved on all three-phase systems, the temperature of the solid wall was raised to a higher value. In this way, thermal transportation from the solid wall to liquid argon was established. As the temperature of the solid wall was high enough, the liquid argon tended to evaporate. From the simulation results, it is observed that during the transformation from hydrophobic to hydrophilic conditions, enhancement of evaporation takes place due to the improvement of thermal transportation behavior. At the nanostructure surface, the active nucleation sites and effective surface area increase which results in evaporation enhancement. With nano slots and nano-level surface roughness, the rate of evaporation increases due to the increase of solid-liquid contact area and effective surface area.

Design and Preclinical Evaluation of Chitosan/Kaolin Nanocomposites with Enhanced Hemostatic Efficiency

In the current study, hemostatic compositions including a combination of chitosan and kaolin have been developed. Chitosan is a marine polysaccharide derived from chitins, a structural component in the shells of crustaceans. Both chitosan and kaolin have the ability to mediate a quick and efficient hemostatic effect following immediate application to injury sites, and thus they have been widely exploited in manufacturing of hemostatic composites. By combining more than one hemostatic agent (i.e., chitosan and kaolin) that act via more than one mechanism, and by utilizing different nanotechnology-based approaches to enhance the surface areas, the capability of the dressing to control bleeding was improved, in terms of amount of blood loss and time to hemostasis. The nanotechnology-based approaches utilized to enhance the effective surface area of the hemostatic agents included the use of Pluronic nanoparticles, and deposition of chitosan micro- and nano-fibers onto the carrier. The developed composites effectively controlled bleeding and significantly improved hemostasis and survival rates in two animal models, rats and rabbits, compared to conventional dressings and QuikClot® Combat Gauze. The composites were well-tolerated as demonstrated by their in vivo biocompatibility and absence of clinical and biochemical changes in the laboratory animals after application of the dressings.

Preparation of thiol-grafted poly(3,4-ethylenedioxythiophene) /yolk-shell carbon sphere/Au composites for the simultaneous detection of caffeic acid and levofloxacin

As the void space can increase the effective surface area, and the mesoporous shell ensures the fast transmission of electrons and ions, the yolk-shell-structured carbon spheres (YRFC) have been explored...

Modified Hydrothermal Route for Synthesis of Photoactive Anatase TiO2/g-CN Nanotubes from Sludge Generated TiO2

Titania nanotube was prepared from sludge generated TiO2 (S-TNT) through a modified hydrothermal route and successfully composited with graphitic carbon nitride (g-CN) through a simple calcination step. Advanced characterization techniques such as X-ray diffraction, scanning and transmission electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, UV/visible diffuse reflectance spectroscopy, and photoluminescence analysis were utilized to characterize the prepared samples. A significant improvement in morphological and optical bandgap was observed. The effective surface area of the prepared composite increased threefold compared with sludge generated TiO2. The optical bandgap was narrowed to 3.00 eV from 3.18 in the pristine sludge generated TiO2 nanotubes. The extent of photoactivity of the prepared composites was investigated through photooxidation of NOx in a continuous flow reactor. Because of extended light absorption of the as-prepared composite, under visible light, 19.62% of NO removal was observed. On the other hand, under UV irradiation, owing to bandgap narrowing, although the light absorption was compromised, the impact on photoactivity was compensated by the increased effective surface area of 153.61 m2/g. Hence, under UV irradiance, the maximum NO removal was attained as 32.44% after 1 h of light irradiation. The proposed facile method in this study for the heterojunction of S-TNT and g-CN could significantly contribute to resource recovery from water treatment plants and photocatalytic atmospheric pollutant removal.

Mechanochemical and Size Reduction Machines for Biorefining

In recent years, we have witnessed an increasing interest in the application of mechanochemical methods for processing materials in biomass refining techniques. Grinding and mechanical pretreatment are very popular methods utilized to enhance the reactivity of polymers and plant raw materials; however, the choice of devices and their modes of action is often performed through trial and error. An inadequate choice of equipment often results in inefficient grinding, low reactivity of the product, excess energy expenditure, and significant wear of the equipment. In the present review, modern equipment employing various types of mechanical impacts, which show the highest promise for mechanochemical pretreatment of plant raw materials, is examined and compared—disc mills, attritors and bead mills, ball mills, planetary mills, vibration and vibrocentrifugal mills, roller and centrifugal roller mills, extruders, hammer mills, knife mills, pin mills, disintegrators, and jet mills. The properly chosen type of mechanochemical activation (and equipment) allows an energetically and economically sound enhancement of the reactivity of solid-phase polymers by increasing the effective surface area accessible to reagents, reducing the amount of crystalline regions and the diffusion coefficient, disordering the supramolecular structure of the material, and mechanochemically reacting with the target substances.