A theoretical study for one-dimensional modeling for VOC in a catalytic converter

Modeling for catalytic oxidation of a volatile organic compound, acetaldehyde for the purpose of controlling tail-pipe emissions from vehicular exhaust was carried out. The model developed was one-dimensional unsteady state model, using mass and energy balance equations to predict results for acetaldehyde conversion in an adiabatic monolith operating under warm-up conditions. The equations consisted of a set of partial differential equations that are coupled and solved using Backward Implicit Scheme. Analysis of the behavior of the converter during warm up period was carried out and it was observed that the warm up was faster for a fresh catalyst and this warm up period could be reduced by introducing hot incoming exhaust gas at higher temperature.     

Synthesis and Characterization of Toluene-3,4-dithiolatoarsenic(III) Derivatives of Dialkyldithiophosphates

Replacement reactions of toluene-3,4-dithiolatoarsenic(III) chloride and sodium salts of dialkyldithiophosphoric acids in 1:1 molar ratio in refluxing anhydrous benzene yielded toluene-3,4-dithiolatoarsenic(III) dialkyldithiophosphate derivatives of the general formula \overline{SC_{6}H_{3}(CH_{3})SA} sS 2 P(OR) 2 [where R = Et, Pr n , Pr i , Bu n and Bu i ]. These newly synthesized derivatives are soluble in organic solvents like benzene, chloroform, and dichloromethane. These derivatives have been characterized by elemental analysis (C, H, S, and As) as well as IR and NMR ( 1 H, 13 C and 31 P) spectral studies.     

Diastereoselective synthesis of a core fragment of ritonavir and lopinavir

A novel approach to the synthesis of Boc-core, a key starting material for ritonavir and lopinavir involving an unprecedented diastereoselective nitroaldol reaction on β-amino aldehyde is disclosed.     

Enantioselective synthesis of (L)-Fmoc-α-Me-Lys(Boc)-OH via diastereoselective alkylation of oxazinone as a chiral auxiliary

Benzyl (2R,3S)-(−)-6-oxo-2,3-diphenyl-4-morpholinecarboxylate (4) was successively alkylated with methyl iodide and 1,4-diiodobutane using a base. In each alkylation step anti-alkylated product formed exclusively. The iodo group was displaced with azide, which served as a precursor for the side-chain amino function. Catalytic hydrogenation with concomitant cleavage of the chiral auxiliary afforded (L)-α-Me-Lys-OH (9) in a total of four steps in good yield. (L)-Fmoc-α-Me-Lys(Boc)-OH (16) was obtained from 9 via regioselective benzyloxycarbonylation. Alternately, (L)-Fmoc-α-Me-Lys(Boc)-OH (16) was obtained via Staudinger reduction of azide (8) in a total of six steps in good yield.     

Chemical activation of egg shell membrane for covalent immobilization of enzymes and its evaluation as inert support in urinary oxalate determination

Egg shell membrane is a novel, robust, microporous, cost effective, easily available organic support material. In recent studies egg shell membranes were utilized as organic support for enzyme immobilization. But low conjugation yield limits its application as good support for biotechnological industries. In present study egg shell membrane was chemically treated to introduce free functional groups for covalent linkage of proteins to increase its conjugation yield and stability of conjugate complex. Many enzymes were tested for immobilization on modified egg shell membrane like oxalate oxidase, glucose oxidase, peroxidase and lipase. A fifteen to sixteen fold increase in conjugation yield was observed when immobilization was performed after chemical treatment in comparison to immobilization on native membrane with slight change in specific activity of immobilized enzyme which ranges from 5% to 15%. Egg shell membrane bound enzymes showed slight changes in their kinetic properties after immobilization. Egg shell membrane bound oxalate oxidase shows detection limit of 1.5 μM when used for urinary oxalate determination. Egg shell membrane support shows no interference to enzyme activity and a good correlation of 0.99 was observed with the values estimated using commercially available Sigma kit. The immobilized oxalate oxidase, glucose oxidase, peroxidase and lipase were stable up to duration of 180 days and there is respective loss of 10%, 13%, 24%, and 33% of initial activity. Overall result strengthens our view of using chemically modified egg shell membrane as solid support for better immobilization of enzymes and can be used in various biotechnological applications.     

A non-enzymatic sensor for hydrogen peroxide based on polyaniline, multiwalled carbon nanotubes and gold nanoparticles modified Au electrode

We describe the construction of a polyaniline (PANI), multiwalled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) modified Au electrode for determination of hydrogen peroxide without using peroxidase (HRP). The AuNPs/MWCNT/PANI composite film deposited on Au electrode was characterized by Scanning Electron Microscopy (SEM) and electrochemical methods. Cyclic voltammetric (CV) studies of the electrode at different stages of construction demonstrated that the modified electrode had enhanced electrochemical oxidation of H(2)O(2), which offers a number of attractive features to develop amperometric sensors based on split of H(2)O(2). The amperometric response to H(2)O(2) showed a linear relationship in the range from 3.0 μM to 600.0 μM with a detection limit of 0.3 μM (S/N = 3) and with high sensitivity of 3.3 mA μM(-1). The sensor gave accurate and satisfactory results, when employed for determination of H(2)O(2) in milk and urine.     

Chemical composition and antimicrobial activity of the inflorescence essential oil of Capillipedium parviflorum (R. Br.) Stapf. from India

Essential oil isolated from the inflorescences of Capillipedium parviflorum (R. Br.) Stapf., collected from Kumaon region of Western Himalaya, India, was investigated by GC and GC-MS. A total of 45 constituents representing 99.0% of the essential oil were identified. The major components of this oil were 4-undecanone (33.2%), 4-undecanol (29.7%), 4-nonanol (13.9%), α-muurolol (5.3%), 4-tridecanone (3.6%), methyl-2-oxo-nonanoate (3.1%), trans-2-hexenyl butanoate (1.1%) and 1-tetradecanol (1.0%). The antimicrobial activity of the essential oil was determined against eight Gram-positive and Gram-negative bacterial strains, as well as two fungal strains. The bioassay showed that the essential oil possessed good antibacterial activity.     

Synthesis of zeolite ZSM‐5: Effect of emulsifiers

Zeolite ZSM‐5 has been synthesized in presence of various emulsifiers. Influence of types and proportions of cationic, anionic and non‐ionic emulsifier has been studied. Cationic emulsifier, cetyl trimethyl ammonium bromide resulted in an amorphous phase, whereas anionic emuisifier, sodium lauryl sulphate afforded crystalline phase, identified as magadiite. Non‐ionic emulsifiers, 1,2,3‐benzotriazole and sorbital mono‐stearate led to the formation of pure crystalline ZSM‐5 phase. Emulsifier concentration was found to affect the process of crystallization, and the crystal size and morphology of ZSM‐5. Emulsifier necessitated higher crystallization temperature and/or longer hydrothermal period. ZSM‐5 crystallization was observed to proceed through magadiite phase formation. In case of benzotriazole, unusual stacked square platelet type morphology and with sorbital monostearate, very small crystals were observed.