Synthesis and evaluation of polythiocyanogen (SCN)x as a rechargeable lithium-ion battery electrode material

Polythiocyanogen, (SCN)_x, is a promising lithium-ion battery electrode material due to its high theoretical capacity (462 mAh g⁻¹), safe operation, inexpensive raw materials, and a simple and less energy-intensive manufacturing process. The (SCN)_x was prepared from the solution of trithiocyanate (SCN)₃⁻ in methylene dichloride (MDC), which was prepared by electrochemical oxidation of ammonium thiocyanate (NH₄SCN) in a two-phase electrolysis medium of 1.0 M NH₄SCN in 0.50 M H₂SO₄ + MDC. The (SCN)₃⁻ underwent auto catalytic polymerization to (SCN)_x during MDC removal. Battery electrodes with (SCN)_x as the active material were prepared, and tested in Swagelok cells using lithium foil as the counter and reference electrode. The cells delivered capacities in the range of 200-275 mAh g⁻¹ at the discharge-charge rate of 0.2 C. The cells were tested up to 20 cycles and showed repeatable performance with a coulombic efficiency of 97% at the 20th cycle. The results presented here indicate that (SCN)_x is a promising lithium-ion battery electrode-material candidate for further studies.     

Role of ceria in CO2 adsorption on NaZSM-5 synthesized using rice husk ash

Ceria (3, 5, 7, 11, 19 wt%) impregnated NaZSM-5 was synthesized and studied for adsorption of CO₂. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), CO₂-temperature programmed desorption (CO₂-TPD) and Brunauer–Emmett–Teller (BET) techniques. The heat of the reaction (ΔH_r) derived from differential scanning calorimetry (DSC) analysis was 490 Btu/lb. XRD analysis showed a decrease in the intensity of patterns with the increase in the ceria loading but crystallization of ceria to larger size was clearly evident for 11 and 19% loading. The surface area decreased for 3 and 5% loading, but increased for 7, 11 and 19% loading illustrating difference in dispersion. The maximum adsorption capacity of CeO₂(5%)/NaZSM-5 was 130 mg/g of sorbent. Extraction of silica from the agricultural waste, rice husk, and its use in the zeolite synthesis was an advantage in this study. Hence, from the study it was concluded that ceria impregnated NaZSM-5 could be treated as a novel material for CO₂ adsorption, as they were regenerable and recyclable. This study can also be applied to all other zeolites.     

Synthesis and Characterization of Maleimide Functionalized Polystyrene-SiO2 /TiO2 Hybrid Nanocomposites by Sol-gel Process

ABSTRACT: Maleimide functionalized polystyrene (PSMA-SiO2/TiO2) hybrid nanocomposites were prepared by sol-gel reaction starting from tratraethoxysilane (TEOS)and titaniumisopropoxide in the solution of maleimide-polystrene in 1,4-dioxane. The hybrid films were obtained by the hydrolysis and polycondensation of (TEOS) and titaniumisopropoxide in maleimide-polystrene solution followed by the Michael addition reaction. The transparency of polymer (PSMA-SiO2/TiO2) hybrid was prepared from polystyrene-titaniumisopropoxide using the gamma-aminopropyltriethoxy silane(gamma-APS) as crosslinking agent by in situ sol-gel process via covalent bonding between the organic-inorganic hybrid nanocomposites.The maleimide functionalized polystyrene was synthesized by Friedal crafts reaction from N-choloromethylmaleimide.The FTIR spectroscopy data conformed the occurrence of Michael addition reaction between the pendant maleimide moieties of the styrene and gamma -aminopropyltriethoxysilane.The chemical structure and morphology of (PSMA-SiO2/TiO2) hybrid nanocomposites were characterized by FTIR, NMR, 13C NMR, SEM and TEM analysis. The results also indicate that the inorganic particles are much smaller in the ternary systems than in the binary systems, the shape of the inorganic particles and compatibility for maleimide-polystrene and inorganic moieties are varied with ratio of the inorganic moieties in the hybrids. Furthermore,TGA and DSC results indicate that the thermal stability of maleimide-polystrene was enhanced through the incorporation of the inorganic moieties in the hybrid materials.     

Thin-film CoB catalyst templates for the hydrolysis of NaBH4 solution for hydrogen generation

Thin-film CoB alloy catalysts were prepared on Ni-foam substrates using electroless as well as electroplating techniques. Electroless plating was carried out using cobalt (II) sulfate as the source of Co²⁺, sodium succinate as the complexing agent, and dimethyamine borane as the source of boron as well as the reducing agent. Electroplating was carried out using cobalt (II) sulfate and cobalt (II) chloride as the sources of cobalt, and boric acid as the source of boron. The thin-film CoB/Ni-foam templates were characterized using ICP, XRD and SEM techniques. The normalized B content was in the range of 1.0–1.30 and 0.20–0.60 wt.% for electroless and electroplated templates, respectively. The B content is less than that required for stoichiometric alloy formation, which indicates the simultaneous deposition of the Co metal along with CoB alloy. An optimum condition of 0.100 M L⁻¹ each of cobalt (II) sulfate heptahydrate Co(SO₄)·7H₂O, sodium succinate (Na₂C₄H₄O₄) and dimethylamine borane (CH₃)₂NHBH₃, at 60 °C with the pH value of 4–5 and a plating time of 1 h was identified for the preparation of the catalyst templates by electroless plating. Where as, 0.125 M L⁻¹ each of cobalt (II) chloride hexahydrate (CoCl₂·6H₂O), Co(SO₄)·7H₂O, 0.125 M L⁻¹ of boric acid at the current density range of 160–320 mA cm⁻² and a temperature of 60 °C was identified as the optimum condition for the electroplating method. Maximum H₂ generation rates of 1.64 and 0.30 L min⁻¹ g⁻¹ of catalyst were obtained with electroless and electroplated thin-film CoB/Ni-foam templates, respectively. The suitability of the electroless plated CoB/Ni-foam catalyst template for extended duration of hydrogen generation from NaBH₄ was studied up to 60 h. Activation energies of 44.47 and 54.89 kJ mol⁻¹ were calculated for electroless and electroplated CoB/Ni-foam catalyst templates, respectively.     

A flexible deadline-driven resource provisioning and scheduling algorithm for multiple workflows with VM sharing protocol on WaaS-cloud

The Journal of Supercomputing - Maximized deployment of workflows in the research organizations has motivated the emergence of multi-tenant environment that offer these workflows deployment as a...     

Multicomponent reaction modelling using a stochastic algorithm

The numerical simulation of multicomponent reactive transport has become a dynamic field of subsurface hydrology. Efficient simulation models are necessary which are capable of representing a multitude of parameters influencing geochemical reactions. The mathematical structure of reactive transport problems in porous media is determined by the decision in the chemical model part whether reactions are kinetically controlled or whether a local equilibrium assumption is made between various species involved in the geochemical reactions. The assumptions made in deterministic models are not hold true for reactions involving chemical species of low concentration. Here the emergent phenomenon evolving out of the random fluctuations of the species is difficult to be captured. The stochastic behaviour of the physicochemical processes can be modelled at mesoscopic level by application of stochastic algorithms. The proposed model was verified by comparing the results of Gillespie’s algorithms with a deterministic solution for PCE and BTEX degradation reactions. Research of the authors is partly supported by the Deutscher Akademischer Austauschdienst (DAAD) and the Deutsche Forschungsgemeinschaft (German Research Foundation) under the grant Ko 1573/8-2, Germany.     

Predicting survival of Escherichia coli O157:H7 in dry fermented sausage using artificial neural networks

The Canadian Food Inspection Agency required the meat industry to ensure Escherichia coli O157:H7 does not survive (experiences > or = 5 log CFU/g reduction) in dry fermented sausage (salami) during processing after a series of foodborne illness outbreaks resulting from this pathogenic bacterium occurred. The industry is in need of an effective technique like predictive modeling for estimating bacterial viability, because traditional microbiological enumeration is a time-consuming and laborious method. The accuracy and speed of artificial neural networks (ANNs) for this purpose is an attractive alternative (developed from predictive microbiology), especially for on-line processing in industry. Data from a study of interactive effects of different levels of pH, water activity, and the concentrations of allyl isothiocyanate at various times during sausage manufacture in reducing numbers of E. coli O157:H7 were collected. Data were used to develop predictive models using a general regression neural network (GRNN), a form of ANN, and a statistical linear polynomial regression technique. Both models were compared for their predictive error, using various statistical indices. GRNN predictions for training and test data sets had less serious errors when compared with the statistical model predictions. GRNN models were better and slightly better for training and test sets, respectively, than was the statistical model. Also, GRNN accurately predicted the level of allyl isothiocyanate required, ensuring a 5-log reduction, when an appropriate production set was created by interpolation. Because they are simple to generate, fast, and accurate, ANN models may be of value for industrial use in dry fermented sausage manufacture to reduce the hazard associated with E. coli O157:H7 in fresh beef and permit production of consistently safe products from this raw material.     

Jet impingement cooling of a horizontal surface in an unconfined porous medium: Mixed convection regime

Two-dimensional slot jet impingement cooling of an isothermal horizontal surface immersed in an unconfined porous medium is simulated numerically to gain insight into thermal characteristics under mixed convection conditions with the limitation of the Darcy model. The jet direction is considered to be perpendicular from the top to the horizontal heated element; therefore, the jet flow and the buoyancy driven flow are in opposite directions. The results are presented in the mixed convection regime with wide ranges of the governing parameters: Péclet number (1 ? Pe ? 1000), Rayleigh number (10 ? Ra ? 100), half jet width (0.1 ? D ? 0.5), and the distance between the jet and the heated portion (0.1 ? H ? 1.0). It is found that the average Nusselt number increases with increase in either Rayleigh number or jet width for high values of Péclet number. The average Nusselt number also increases with decrease in the distance between the jet and the heated portion. It is shown that mixed convection mode can cause minimum average Nusselt number at two values of Péclet number and a maximum average Nusselt number occurs in between theses two Péclet numbers at higher Rayleigh number due to counteraction of jet flow against buoyancy driven flow. Hence careful consideration must be given while designing a system of jet impingement cooling through porous medium.     

Photocatalytic degradation of aqueous propoxur solution using TiO2 and Hbeta zeolite-supported TiO2

Photocatalytic activity of TiO2 and zeolites supported TiO2 were investigated using propoxur as a model pollutant. Hbeta, HY and H-ZSM-5 zeolites were examined as supports for TiO2. Hbeta was chosen as the TiO2 support based on the adsorption capacity of propoxur on these zeolites (Hbeta>HY=H-ZSM-5). TiO2/Hbeta photocatalysts with different wt.% were prepared and characterized by XRD, FT-IR and BET surface area. The progress of photocatalytic degradation of aqueous propoxur solution using TiO2 (Degussa P-25) and TiO2 supported on Hbeta zeolite was monitored using TOC analyzer, HPLC and UV-vis spectrophotometer. The degradation of propoxur was systematically studied by varying the experimental parameters in order to achieve maximum degradation efficiency. The initial rate of degradation with TiO2/Hbeta was higher than with bare TiO2. TOC results revealed that TiO2 requires 600min for complete mineralization of propoxur whereas TiO2/Hbeta requires only 480min. TiO2/Hbeta showed enhanced photodegradation due to its high adsorption capacity on which the pollutant molecules are pooled closely and hence degraded effectively.     

Preparation of thermally stable nanocrystalline hydroxyapatite by hydrothermal method

Thermally stable hydroxyapatite (HAp) was synthesized by hydrothermal method in the presence of malic acid. X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA) was done on the synthesized powders. These analyses confirmed the sample to be free from impurities and other phases of calcium phosphates, and were of rhombus morphology along with nanosized particles. IR and Raman analyses indicated the adsorption of malic acid on HAp. Thermal stability of the synthesized HAp was confirmed by DTA and TGA. The synthesized powders were thermally stable upto 1,400 degrees C and showed no phase change. The proposed method might be useful for producing thermally stable HAp which is a necessity for high temperature coating applications.