Use of a New Polymer Anchored Cu(II) Azo Complex Catalyst for the Efficient Liquid Phase Oxidation Reactions

A new polymer anchored copper(II) azo complex has been synthesized and characterized by using scanning electron microscope (SEM), thermogravimetric analysis (TGA), elemental analysis, atomic absorption spectroscopy (AAS) and spectrometric methods like diffuse reflectance spectra of solid (DRS) and Fourier transform infrared spectroscopy (FTIR). The immobilized Cu(II) catalyst shows excellent catalytic activity in oxidation of cyclohexene, styrene, benzyl alcohol and ethylbenzene in presence of tert-butylhydroperoxide (TBHP) as an oxidant. The effects of different solvents, oxidants, temperature, substrate oxidant ratio and amount of catalyst were also studied. The catalytic results reveal that the polymer-anchored Cu(II) azo complex catalyst can be recycled more than five times without appreciable loss in the catalytic activity.     

Formation of rice flavor powder with α-cyclodextrin by spray drying

The spray drying conditions affect the retention of flavor compounds in the mimetic rice flavor powder. The wall material is one of the factors of pronounced importance that dictates the flavor retention of the rice flavor powder during spray drying. In this study, we focused on making rice flavor powder by spray drying from mimetic rice flavor oil and the binary mixtures of α-cyclodextrin (α-CD) and highly branched cyclic dextrin (HBCD) as wall material. The composition of α-CD and HBCD influenced the flavor retention and the amount of surface oil on the resultant spray-dried powders. The optimum α-CD content was 67%, at which a spray-dried powder of the highest flavor retention and the least amount of surface oil was obtained.     

Supercritical Carbon Dioxide Extraction of Eugenol from Clove Buds

Isolation of eugenol from dried clove buds (Syzygium aromaticum Linn) of Indian origin was carried out using supercritical carbon dioxide (SC-CO₂) extraction. Optimization of its process parameters such as temperature, pressure and time of extraction has been conducted using response surface methodology. The optimized conditions that provided the optimum yield of eugenol were a sample size of 20 g of clove powder of particle diameter 0.5 mm at a temperature of 60°C and pressure of 250 bar for 90 min extracting time at a flow rate of 2 l?min^?1 of CO₂. Statistical analyses conducted on the extraction parameters concluded that extraction temperature have significant effect on the yield of eugenol, whereas extraction pressure and time do not. The results obtained are in accordance to the basic principle of supercritical fluid phase equilibrium behavior. Solubility of eugenol in SC-CO₂ under different temperature and pressure regimes have been determined experimentally and values were used to construct a correlated Chrastil equation in linear form to allow the prediction of solubility of eugenol in SC-CO₂ under different extraction conditions. Using dimensionless numbers, an empirical correlation was also deduced for characterization of the extraction process of eugenol in SC-CO₂ considering overall fixed bed behavior for clove matrix and mass transfer coefficients in supercritical phases.     

Experimentally- and theoretically-evaluated ultimate 3-dimensional elastic constants of trans-1,4-polyisoprene α and β crystalline forms on the basis of the newly-refined crystal structure information

The ultimate 3-dimensional elastic constants and compliance tensors have been evaluated for trans-1,4-polyisoprene (Gutta percha) α and β crystalline forms experimentally and theoretically. The theoretical estimation was performed by the molecular mechanics method on the basis of the newly-refined atomic coordinates obtained by quantitative analysis of the crystal structures using many numbers of X-ray reflections from the highly-oriented and highly-pure α and β crystalline samples. The calculated Young's modulus along the chain axis was 85.8 GPa for the α form and 72.3 GPa for the β form, in good agreement with the experimentally-obtained X-ray crystallite moduli, 72.4 GPa and 61.4 GPa, respectively.     

Sucrose retards the reaction of non-calcium geopolymers: An implication for developing kinetics-controlling admixtures

For geopolymers (no or low calcium), the chemical admixtures designed for ordinary portland cement are either inefficient or ineffective. In this study, the effects of sucrose on the kinetics of geopolymerization (no calcium) were investigated. From calorimetry tests, we found sucrose retarded the geopolymerization of sodium silicate-activated metakaolin. This retardation is unlikely to be related to the dissolution of metakaolin, since sucrose also hindered the reaction of the synthetic gel (no metakaolin) as evidenced by the smaller particle sizes under microscopy. Further spectroscopy and total organic carbon (TOC) tests indicated that sucrose did not adsorb or chemically interact with the synthetic aluminosilicate gel and the intermediate (alumino)silicate species. In contrast, the retardation mechanism was found to be due to the interaction of sucrose with alkalis in the solution, partially based on the structural characterization of sucrose under alkaline condition. To the best of our knowledge, this work is the first of its type to explore and understand the reaction-controlling admixtures for non-calcium geopolymers.     

A finite element approach for analyzing the effect of cushion type and thickness on pressure ulcer

Immobilization or continuous sitting with a constant posture for a long time in office environment causes sub-dermal tissue damage. Tissue damage occurs because of continuous prolonged compression of buttock soft tissue under body weight. It is treated as the end result of cell death or tissue deformation which ultimately gives rise to pressure ulcer. Although the sub-dermal tissue refers to the tissue beneath the skin, it is the tissue just below the bony portion undergoes maximum deformation because the muscle endures a continuous high stress. In this work, a simple but practical numerical approach has been proposed to estimate the maximum stress beneath the bony structure (ischial tuberosity). The model is validated with experimental data from the literature. Effect of properties of cushion material, loading angle and thickness of cushion has been analyzed. The cushion properties and thickness that can reduce maximum stress at ischial tuberosity have been demonstrated. The effect of sitting posture on maximum stress at ischial tuberosity has also been shown.     

An overview of caprolactam synthesis

Caprolactam is the precursor of many industrial chemical productions as in nylon industry, plastic industry, paint industry, lysine synthesis and cross-linking for polyurethanes. The production of caprolactam has been focus much from last three decades among the scientific community to fulfill the industrial need under environment precautions. Herein a sequential and explanatory review broadly covering the transformation of a different substrate as cyclohexanone oxime, cyclohexanone, cyclohexanol, cyclohexane, and biorenewable sources into caprolactam is presented. For every substrate, a wide range of catalyst including homogeneous as well as the heterogeneous system has been deeply considered. This study will be helpful for developing alternative industrial route for production of caprolactam.     

Comprehensive study of metal on the characteristic properties of epoxy resins

A series of different type of epoxy resins containing metal(s) have been prepared by the using cobalt acrylate (CoA₂), nickel acrylate(NiA₂),bismuth acrylate (BiA₃) during resinification. The values of epoxide equivalent weight, chlorine content increases whereas hydroxyl content, refractive index decreases in the presence of metal acrylate(s). The influence of complex formation of metal acrylate with ether linkage of epoxy resins were investigated by spectroscopy. Epoxy resins containing cobalt acrylate which was cured by p‐acetylbenzilidinetriphenylarsoniumylide (p‐ABTAY) shows better conducting properties in comparison to NiA₂ and BiA₃ containing epoxy resins. The dispersion of metal(s) in epoxy resins matrix was confirmed by scanning electron microscope (SEM). The glass transition temperature of epoxy resins containing CoA₂ is lower than that of blank epoxy resins and epoxy resins containing bismuth and nickel acrylate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010