Structural and electrochemical investigation of novel hybridized MnO2/V2O5 nanocomposites prepared by one-step microwave-assisted method for electrochemical supercapacitor application

Journal of Materials Science: Materials in Electronics - Pure V2O5 and MnO2/V2O5 hybrid nanocomposites were synthesized by microwave-assisted method for electrochemical supercapacitor application....     

Monascus pigment production by solid-state fermentation with corn cob substrate

Natural pigments are an important alternative to potentially harmful synthetic dyes. We investigated the feasibility of corn cob powder as a substrate for production of pigments by Monascus purpureus KACC 42430 in solid-state fermentation. A pigment yield of 25.42 OD Units/gram of dry fermented substrate was achieved with corn cob powder and optimized process parameters, including 60% (w/w) initial moisture content, incubation at 30°C, inoculation with 4 mL of spores/gram of dry substrate, and an incubation period of 7 days. Pigment yield using corn cobs greatly exceeded those of most other agricultural waste substrates. The pigments were stable at acidic pH, high temperatures, and in salt solutions; all important considerations for industrial applications. Our results indicate the viability of corn cob substrate in combination with M. purpureus for industrial applications.     

Hydrogenation properties of pure magnesium and magnesium–aluminium thin films

We have studied the hydrogenation/dehydrogenation behaviour of multilayered stacks of Pd/Mg/Pd and Pd–Fe(Ti)–Mg–Al–Mg–Fe(Ti)–Pd grown by electron beam physical vapour deposition. The palladium coating was deposited at both sides of the structure to ensure a fast dissociation rate and good transport properties for hydrogen as well as to avoid oxidation of magnesium either from atmosphere as from the substrate surface. Fe and Ti layers were included in the stack composition in order to assess their possible catalyst effect as well as to prevent the formation of Mg_xPd_y intermetallics during the thermal treatments. We have studied the structure evolution after thermal treatments as well as after the hydrogenation and dehydrogenation processes using XRD. We have also followed the reactions kinetics by resistometry and differential scanning calorimetry. The nanostructured Mg films have been hydrogenated at temperature as low as 50 °C in few minutes. Adding aluminium to magnesium has improved its hydrogenation capacity. We have also observed that the formation of an Mg_xAl_y intermetallic before hydrogenation improves the storage capacity. We have confirmed that titanium is a better catalyst for the hydrogenation/dehydrogenation of the Mg films.     

Polished nanopipets: new probes for high-resolution scanning electrochemical microscopy

Nanometer-sized pipets pulled from glass or quartz capillaries have been extensively used as probes for scanning electrochemical microscopy (SECM) and scanning ion conductance microscopy (SICM). A small separation distance between such a probe and the sample, which is required for high-resolution SECM measurements, may be hard to attain because of considerable roughness of the pipet tip. In this Letter, we report the preparation and characterization of polished nanopipet SECM probes with a much smoother tip edge. Using polished pipets, quantitative SECM measurements were performed at extremely short tip/substrate distances (e.g., d ≈ 1 nm).     

Energy Absorption Characteristics of Dual Phase Steel Tubes Under Static and Dynamic Loading

Abstract: Thin walled tubes are used as energy absorbing elements in automobile applications. The circular tube proves to be a popular energy absorber because it provides a reasonably constant operating force which is the prime characteristics of the energy absorber. Square and rectangular tubes are widely used in automobile structures as these cross sections are suitable for welding with other components in the structure and hence highly preferred. Advanced high strength steels can be utilised to absorb crash energy and minimise intrusion in the occupant zone. In this work circular, square and rectangular tubes made up of dual phase steel are tested in static and dynamic conditions. All the tubes are subjected to same amount of input impact energy but the specific energy absorption is higher in circular steel tubes. The results are compared with those for annealed tubes of same cross section. The effect of impact velocity is also studied by keeping the impact mass constant and varying the drop height. The experimental results are compared with the theoretical results and good agreement is found.     

Long-term properties of steel fibre reinforced marine concrete

The paper presents some results from a continuing research programme which aims to develop steel fibre reinforced concrete (sfrc) for marine applications and to investigate its durability. A mix of proportions by weight of 1:1.5:0.86 was adopted which was reinforced with three types of steel fibres, namely, low carbon steel, corrosion resistant and melt extract. Prism specimens were cured under marine exposure, both in the laboratory and at Aberdeen beach, for up to 2000 wet-dry cycles (1250 days) and were tested at regular intervals of age. The paper presents results on long-term compressive strength, flexural strength and ductility as measured from flexural load-deflection curves. The state of fibres, with respect to corrosion, is also discussed. The results indicate that melt extract fibres, although least effective from the mechanical strength point of view, are the most suitable for marine applications.     

Production and mechanical properties of SiC<Subscript>p</Subscript> particle-reinforced 2618 aluminum alloy composites

In this study, 2618 aluminum alloy metal matrix composites (MMCs) reinforced with two different sizes and weight fractions of SiC_p particles upto 10% weight were fabricated by stir cast method and subsequent forging operation. The effects of SiC_p particle content and size of the particles on the mechanical properties of the composites such as hardness, tensile strength, hot tensile strength (at 120 °C), and impact strength were investigated. The density measurements showed that the samples contained little porosity with increasing weight fraction. Optical microscopic observations of the microstructures revealed uniform distribution of particles and at some locations agglomeration of particles and porosity. The results show that hardness and tensile strength of the composites increased, with decreasing size and increasing weight fraction of the particles. The hardness and tensile strength of the forged composites were higher than those of the cast samples.     

Adsorption of reactive dye from an aqueous solution by chitosan: isotherm, kinetic and thermodynamic analysis

The adsorption of Remazol black 13 (Reactive) dye onto chitosan in aqueous solutions was investigated. Experiments were carried out as function of contact time, initial dye concentration (100-300mg/L), particle size (0.177, 0.384, 1.651mm), pH (6.7-9.0), and temperature (30-60 degrees C). The equilibrium adsorption data of reactive dye on chitosan were analyzed by Langmuir and Freundlich models. The maximum adsorption capacity (qm) has been found to be 91.47-130.0mg/g. The amino group nature of the chitosan provided reasonable dye removal capability. The kinetics of reactive dye adsorption nicely followed the pseudo-first and second-order rate expression which demonstrates that intraparticle diffusion plays a significant role in the adsorption mechanism. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption. The positive value of the enthalpy change (0.212kJ/mol) indicated that the adsorption is endothermic process. The results indicate that chitosan is suitable as adsorbent material for adsorption of reactive dye form aqueous solutions.     

Study on ultrasound assisted precipitation of CL-20 and its effect on morphology and sensitivity

Applying ultrasound to crystallizing systems offers significant advantages for modifying and improving the processes as well as quality of products. This paper reports on ultrasound assisted reprecipitation of CL-20 to obtain fine particles as well as to achieve desired morphology, which will improve insensitivity characteristics. In this study, CL-20 has been reprecipitated by sonication process and has been characterized by DSC, SEM and particle size analysis. The results are compared with control CL-20 sample (unsonicated). SEM photographs revealed that sonication process offer uniform crystalline morphology without any agglomeration. The particle size of sonicated CL-20 sample obtained is around 5+/-1 microm with a narrow particle size distribution. The DSC thermogram of sonicated and unsonicated sample is identical. CL-20 samples were subjected to impact and friction sensitivity experiments, the results indicate the sensitivity characteristics reduced considerably. Ultrasonic assisted crystallization technique reduces the time of reprecipitation considerably with an enhanced recovery of CL-20 with a very narrow particle size distribution.     

Facile solution deposition of ZnIn2S4 nanosheet films on FTO substrates for photoelectric application

In this paper, ZnIn(2)S(4) perpendicular nanosheet films have been directly deposited on FTO substrates by a facile hydrothermal method and investigated as the electrode materials for solar cells. The crystal structure, morphology, and optical properties of the obtained ZnIn(2)S(4) films were characterized by measurements such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectrum (EDS), X-ray photoelectron spectrum (XPS) and UV-vis spectra. The results revealed a uniform perpendicular ZnIn(2)S(4) film with thickness of 4 μm and with an average nanosheet thickness of about 30 nm on FTO substrate, along with the band gap of 2.35 eV. The reaction conditions influencing the formation of ZnIn(2)S(4) films, such as the substrate treatment and reaction time were investigated. A possible mechanism for the formation of ZnIn(2)S(4) films on FTO substrates under hydrothermal conditions has been proposed. Furthermore, after heat treatment, the ZnIn(2)S(4) film electrode exhibited a photoelectrical conversion efficiency of 0.23% in FTO/ZnIn(2)S(4)/polysulfide/Au liquid-junction solar cell under AM 1.5 (100 mW cm(-2)).