Activated carbon derived from tree bark biomass with promising material properties for supercapacitors

Journal of Solid State Electrochemistry - Activated carbon from tree bark (ACB) has been synthesized by a facile and environmentally friendly activation and carbonization process at different...     

Solvent effects on oxygen atom transfer reaction between manganese(V)-oxo corrole and alkene

Pseudo-first order reaction rate constants of 5,10,15-tris（pentafluorophenyl）corrole Mn（V）-oxo (F₁₅CMn（V）-oxo),5,15-bis（pentafluorophenyl）-10-（phenyl）corrole Mn（V）-oxo(F₁₀CMn（V）-oxo),5,15- bis（phenyl）-10-（pentafluorophenyl）corrole Mn（V）-oxo（F₅CMn（V）-oxo） and 5,10,15-tris（phenyl）corrole Mn（V）-oxo（F₀CMn（V）-oxo） with a series of alkene substrates in different solvents were determined by UV-vis spectroscopy.The results indicated that the oxygen atom transfer pathway between Mn（V）-oxo corrole and alkene is solvent-dependent.     

β-Octafluorinated tetrakis(ethoxycarbonyl)porphyrin

Tetrakis(alloxycarbonyl)porphyrin and its β-octafluoro-substituted derivatives were synthesized via Lindsey method and transformed to their zinc complexes.Single crystal X-ray structures of corresponding Zn(Ⅱ) porphyrins revealed that β-octafluorination will give more compactness of porphyrin moieties in the crystal structure owing to the hydrogen bonding interactions involving β-fluorine atoms.An unusual six-coordinated Zn(Ⅱ) was found via intramolecular coordination of oxygen atom of meso-substituents with central Zn(Ⅱ).     

Ultrasonic-assisted preparation and characterization of CdS nanoparticles in the presence of a halide-free and low-cost ionic liquid and photocatalytic activity

An ultrasonic-assisted and environmentally favorable method is proposed for preparation of CdS nanoparticles in the presence of a halide-free and low-cost room-temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium ethyl sulfate, ([EMIM][EtSO₄]). The prepared samples were characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform-infrared (FT-IR). Diffuse reflectance spectra (DRS) of the products reveal a blue shift of 1.45 eV relative to bulk CdS, which can be attributed to the quantum confinement effect of the prepared nanoparticles. Investigation of photocatalytic activity for the CdS nanoparticles towards photodegradation of methylene blue (MB) demonstrates that photodegradation of MB increases with RTIL content of the media using visible and UV irradiations.     

Template-free preparation and characterization of nanocrystalline ZnO in aqueous solution of [EMIM][EtSO4] as a low-cost ionic liquid using ultrasonic irradiation and photocatalytic activity

A fast, template-free, and environmentally benign green route for the preparation of nanocrystalline ZnO in aqueous solution of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM][EtSO₄], room-temperature ionic liquid (RTIL), via ultrasonic irradiation is proposed. The X-ray diffraction (XRD) studies display that the products are excellently crystallized in the form of wurtzite hexagonal. Energy-dispersive X-ray spectroscopy (EDX) investigations reveal the products are extremely pure. The morphology of as-prepared nanocrystalline ZnO was characterized by scanning electron microscopy (SEM). Diffuse reflectance spectra (DRS) of the products with absorption maxima at 359 nm show blue shift relative to the bulk ZnO with absorption at 384 nm that can be attributed to quantum confinement effect of nanocrystalline ZnO. A possible formation mechanism of the nanocrystalline ZnO using ultrasonic irradiation in aqueous solution of the RTIL is presented. The results demonstrate that photocatalytic activity of the nanocrystalline ZnO prepared in the presence of the RTIL is higher than the prepared sample in water.     

Numerical analysis on cooling performance of counterflowing jet over aerodisked blunt body

This study investigates a combined technique of both an active flow control concept that uses counterflowing jets and an aerodisk spike as a new method to significantly modify external flowfields and heat reduction in a hypersonic flow around a nose cone. The coolant gas (Carbon Dioxide and Helium) is chosen to inject from the tip of the nose cone to cool the recirculation region. The gases are considered to be ideal, and the computational domain is axisymmetric. The analysis shows that the counterflowing jet has significant effects on the flowfield and reduces the heat load over the nose cone. The Helium jet is found to have a relatively more effective cooling performance.     

Water assisted growth of C₆₀ rods and tubes by liquid-liquid interfacial precipitation method

C?? nanorods with hexagonal cross sections are grown using a static liquid-liquid interfacial precipitation method in a system of C??/m-dichlorobenzene solution and ethanol. Adding water to the ethanol phase leads instead to C?? tubes where both length and diameter of the C?? tubes can be controlled by the water content in the ethanol. Based on our observations we find that the diameter of the rods/tubes strongly depends on the nucleation step. We propose a liquid-liquid interface growth model of C?? rods and tubes based on the diffusion rate of the good C?? containing solvent into the poor solvent as well as on the size of the crystal seeds formed at the interface between the two solvents. The grown rods and tubes exhibit a hexagonal solvate crystal structure with m-dichlorobenzene solvent molecules incorporated into the crystal structure, independent of the water content. An annealing step at 200 °C at a pressure < 1 kPa transforms the grown structures into a solvent-free face centered cubic structure. Both the hexagonal and the face centered cubic structures are very stable and neither morphology nor structure shows any signs of degradation after three months of storage.     

Simultaneous determination of valproic acid and its main metabolite in human plasma using a small scale dispersive liquid–liquid microextraction followed by gas chromatography–flame ionization detection

A simple, sensitive, and rapid analytical method has been developed and validated for the extraction and quantification of valproic acid and its main metabolite (3-heptanone) in human plasma. Initially, the proteins of plasma were precipitated with trifluoroacetic acid. Then a very small volume of a water-immiscible extractant and acetonitrile was mixed and rapidly injected into the pre-treated plasma sample. For further turbidity (dispersion of the extractant into sample solution), the cloudy solution was vortexed. After centrifugation, the settled phase was injected into gas chromatography-flame ionization detection. The effective parameters, such as type and volume of extraction and disperser solvents, vortex time, and pH were studied and optimized. The limits of detection of valproic acid and 3-heptanone were obtained, 0.065 and 0.015 mg L^?1, respectively. An acceptable precision was obtained for a concentration of 2 mg L^?1 of each analyte (relative standard deviation?≤?8%). The average absolute recoveries (n?=?3) of valproic acid and 3-heptanone were 52?±?2 and 42?±?1%, respectively. The validated method has been successfully used in analysis of the analytes in human plasma samples.     

Hybrid electrochemical capacitors in aqueous electrolytes: Challenges and prospects

In an internal hybrid capacitor, at least one electrode displays battery-like charge/discharge and the other electrode stores charge reversibly at the electric double-layer (EDL). Recently, a plethora of hybrid cells in aqueous electrolytes have been proposed by coupling an EDL electrode with a battery electrode, the latter made from a variety of redox-active/redox-mediator species either dissolved in the electrolyte or adsorbed/immobilized in nanoporous electrodes. This review presents current opinions, discusses challenges, and supplies recommendation about the hybrid cells with aqueous electrolytes and carbon electrodes.