Intertwined Nanocarbon and Manganese Oxide Hybrid Foam for High‐Energy Supercapacitors

Rapid charging and discharging supercapacitors are promising alternative energy storage systems for applications such as portable electronics and electric vehicles. Integration of pseudocapacitive metal oxides with single‐structured materials has received a lot of attention recently due to their superior electrochemical performance. In order to realize high energy‐density supercapacitors, a simple and scalable method is developed to fabricate a graphene/MWNT/MnO₂ nanowire (GMM) hybrid nanostructured foam, via a two‐step process. The 3D few‐layer graphene/MWNT (GM) architecture is grown on foamed metal foils (nickel foam) via ambient pressure chemical vapor deposition. Hydrothermally synthesized α‐MnO₂ nanowires are conformally coated onto the GM foam by a simple bath deposition. The as‐prepared hierarchical GMM foam yields a monographical graphene foam conformally covered with an intertwined, densely packed CNT/MnO₂ nanowire nanocomposite network. Symmetrical electrochemical capacitors (ECs) based on GMM foam electrodes show an extended operational voltage window of 1.6 V in aqueous electrolyte. A superior energy density of 391.7 Wh kg^?1 is obtained for the supercapacitor based on the GMM foam, which is much higher than ECs based on GM foam only (39.72 Wh kg^?1). A high specific capacitance (1108.79 F g^?1) and power density (799.84 kW kg^?1) are also achieved. Moreover, the great capacitance retention (97.94%) after 13 000 charge–discharge cycles and high current handability demonstrate the high stability of the electrodes of the supercapacitor. These excellent performances enable the innovative 3D hierarchical GMM foam to serve as EC electrodes, resulting in energy‐storage devices with high stability and power density in neutral aqueous electrolyte.     

Synthesis and reactive features of a terpolymer: Poly(N‐vinyl‐2‐pyrrolidone‐co‐vinyl acetate‐co‐glycidyl methacrylate)

A polyvinyl pyrrolidone terpolymer system is described that can be chemically cross‐linked at moderate, 70–100°C, temperatures. The system has significant potential for development of durable long‐lasting pyrrolidone coatings in a wide range of applications, particularly in water filtration membrane construction where leaching is an unresolved, serious problem. The synthesis of the terpolymer, poly(N‐vinyl‐2‐pyrrolidone‐co‐vinyl acetate‐co‐glycidyl methacrylate), by free radical polymerization is described. The reactive features of this terpolymer are presented in the context of acidic anhydride curing. In a polar aprotic solvent, the terpolymer is reacted with poly(methyl vinyl ether‐co‐maleic acid) and cured thermally. Key aspects of the terpolymer synthesis and the acid anhydride cross‐linking reaction using DSC, rheology, FTIR, and a small molecule model system to study the cross‐linking chemistry are presented. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Exergy analysis of a solar assisted absorption cooling system on an hourly basis in villa applications

A solar assisted absorption refrigeration system (SAARS) was designed for acclimatizing of villas in Mardin which is located in Turkey and the performance of the system under different temperatures was analyzed by using MATLAB. Hourly cooling load calculation of the villas was done between 15th of May and 15th of September by considering the season for the cooling. Cooling capacity of the system (SAARS) was calculated as 106 kW. During the cooling period, the temperature of the environment shows the alteration between 40.3 °C and 13.2 °C. In the study, hourly exergy loss values are calculated with the software developed in matlab program and for the entire components of SAARS. The effect of the temperature alterations of the dead state on the exergy results is determined by taking dead state temperature as 25 °C and with more realistic approach, by taking it as the environment temperature. It was observed that the most of the exergy losses in the system have taken place in the solar collectors and then in the generator. Exergy loss in the collector changes between 10% and 70% while exergy loss in the generator changes between 5% and 8%. The effects of environmental temperature and solar insolation were stated for optimization.     

Copper(II) and zinc(II) biosorption on Pinus sylvestris L

The biosorption properties of copper(II) and zinc(II) onto a cone biomass of Pinus sylvestris L. was investigated by using batch techniques. The biosorption studies carried out with single metal solutions. The removal of copper(II) and zinc(II) from aqueous solution increased with pH and sharply decreased when pH of the solution was decreased. The maximum biosorption efficiency of P. sylvestris was 67% and 30% for Cu(II) and Zn(II), respectively. Batch kinetic and isotherm of biosorption metal ions were investigated. The second-order kinetic model was used to correlate the experimental data. The Freundlich and Langmuir model can describe the adsorption equilibrium of metal(II) on cone biomass. The biosorption constants were found from the Freundlich and Langmuir isotherms at 25 degrees C. It is found that the biosorption data of metals on cone biomass fitted both the Freundlich and Langmuir adsorption models.     

Influence of reducing conditions on metallic elements released from various contaminated soil samples

The redox conditions of soil may have significant consequences for the mobility of metallic elements (ME), but unlike pH, very few studies have investigated this parameter. A procedure was established to study the solubilization of ME from soil samples in various reducing conditions using a batch method and sodium ascorbate solutions. The change in redox potential from +410 to +10 mV was studied from four contaminated soil samples (designated A-D) of different origins and compositions. The results showed that ME mobilization greatly increased with decreasing redox potential within a limited and very sensitive range. Depending on the soil sample studied, various sensitive ranges of potentials were obtained (A, 220-345 mV; B, 280-365 mV; C, 260-360 mV; and D, 240-380 mV), and the induced percentages of ME mobilization varied (i.e., maximal values for Zn: A, 45%; B, 59%; C, 53%; and D, 58%). The results could be explained by the combined effect of potential and pH decrease on ME-carrying phases; in particular, Fe and Mn (oxy)hydroxides.     

Electrical characterization of composition modulated In(1-x)Sb(x) nanowire field effect transistors by scanning gate microscopy

In this work high quality crystalline In(1_x)Sb(x) nanowires (NWs) are synthesized via a template-based electrochemistry method. Energy dispersive spectroscopy studies show that composition modulated In(1-x)Sb(x) (x approximately 0.5 or 0.7) nanowires can be attained by selectively controlling the deposition potential during growth. Single In(1-x)Sb(x) nanowire field effect transistors (NW-FETs) are fabricated to study the electrical properties of as-grown NWs. Using scanning gate microscopy (SGM) as a local gate the I(ds)-V(ds) characteristics of the fabricated devices are modulated as a function of the applied gate voltage. Electrical transport measurements show n-type semiconducting behavior for the In0.5Sb0.5 NW-FET, while a p-type behavior is observed for the In0.3Sb0.7 NW-FET device. The ability to grow composition modulated In(1-x)Sb(x) NWs can provide new opportunities for utilizing InSb NWs as building blocks for low-power and high speed nanoscale electronics.     

Gating of Single‐Layer Graphene with Single‐Stranded Deoxyribonucleic Acids

Patterning of biomolecules on graphene layers could provide new avenues to modulate their electrical properties for novel electronic devices. Single‐stranded deoxyribonucleic acids (ssDNAs) are found to act as negative‐potential gating agents that increase the hole density in single‐layer graphene. Current–voltage measurements of the hybrid ssDNA/graphene system indicate a shift in the Dirac point and “intrinsic” conductance after ssDNA is patterned. The effect of ssDNA is to increase the hole density in the graphene layer, which is calculated to be on the order of 1.8 × 10¹² cm^?2. This increased density is consistent with the Raman frequency shifts in the G‐peak and 2D band positions and the corresponding changes in the G‐peak full width at half maximum. Ab initio calculations using density functional theory rule out significant charge transfer or modification of the graphene band structure in the presence of ssDNA fragments.     

Patterning and Templating for Nanoelectronics

The semiconductor industry will soon be launching 32 nm complementary metal oxide semiconductor (CMOS) technology node using 193 nm lithography patterning technology to fabricate microprocessors with more than 2 billion transistors. To ensure the survival of Moore's law, alternative patterning techniques that offer advantages beyond conventional top‐down patterning are aggressively being explored. It is evident that most alternative patterning techniques may not offer compelling advantages to succeed conventional top‐down lithography for silicon integrated circuits, but alternative approaches may well indeed offer functional advantages in realising next‐generation information processing nanoarchitectures such as those based on cellular, bioinsipired, magnetic dot logic, and crossbar schemes. This paper highlights and evaluates some patterning methods from the Center on Functional Engineered Nano Architectonics in Los Angeles and discusses key benchmarking criteria with respect to CMOS scaling.     

The effects of a starter culture on the formation of biogenic amines in Turkish soudjoucks

The effects of starter culture containing Lactobacillus sake, Pediococcus pentosaceus, Staphylococcus carnosus plus Staphylococcus xylosus on the formation of biogenic amines during ripening of Turkish soudjoucks were investigated. Determination of eight different biogenic amines was carried out by reverse-phase high performance liquid chromatography (HPLC) using diode array detection. It was found that aerobic plate counts (APC) decreased in the samples with added starter culture. Lactic acid bacteria counts increased in both the controls and samples with added starter during ripening. Total Enterobacteriaceae (ENT) counts decreased on the 30th day for vacuum packed and starter added samples. Yeast counts decreased only in vacuum packed and starter added samples on the 30th day. No biogenic amines were found in ground meat samples. Putrescine (PU) and tyramine (TYR) were determined in all control samples during the storage at 4°C. Starter addition inhibited formation of PU but not TYR.