Development of Petri Net-Based Dynamic Model for Improved Production of Farnesyl Pyrophosphate by Integrating Mevalonate and Methylerythritol Phosphate Pathways in Yeast

In this case study, we designed a farnesyl pyrophosphate (FPP) biosynthetic network using hybrid functional Petri net with extension (HFPNe) which is derived from traditional Petri net theory and allows easy modeling with graphical approach of various types of entities in the networks together. Our main objective is to improve the production of FPP in yeast, which is further converted to amorphadiene (AD), a precursor of artemisinin (antimalarial drug). Natively, mevalonate (MEV) pathway is present in yeast. Methyl erythritol phosphate pathways (MEP) are present only in higher plant plastids and eubacteria, but not present in yeast. IPP and DAMP are common isomeric intermediate in these two pathways, which immediately yields FPP. By integrating these two pathways in yeast, we augmented the FPP synthesis approximately two folds higher (431.16 U/pt) than in MEV pathway alone (259.91 U/pt) by using HFPNe technique. Further enhanced FPP levels converted to AD by amorphadiene synthase gene yielding 436.5 U/pt of AD which approximately two folds higher compared to the AD (258.5 U/pt) synthesized by MEV pathway exclusively. Simulation and validation processes performed using these models are reliable with identified biological information and data.     

BLEND MEMBRANES FOR DIRECT METHANOL AND PROTON EXCHANGE MEMBRANE FUEL CELLS

Sulphonated polystyrene ethylene butylene polystyrene(SPSEBS)prepared with 35%sulphonation was found to be highly elastic and enlarged up to 300%-400%of its initial length.It absorbed over 110%of water by weight.A major drawback of this membrane is its poor mechanical properties which are not adequate for use as polymer electrolytes in fuel cells.To overcome this,SPSEBS was blended with poly(vinylidene fluoride)(PVDF),a hydrophobic polymer.The blend membranes showed better mechanical properties than the base polymer.The effect of PVDF content on water uptake,ion exchange capacity and proton conductivity of the blend membranes was investigated.This paper presents the results of recent studies applied to develop an optimized in-house membrane electrode assembly(MEA)preparation technique combining catalyst ink spraying and assembly hot pressing.Easy steps were chosen in this preparation technique in order to simplify the method,aiming at cost reduction.The open circuit voltage for the cell with SPSEBS is 0.980 V which is higher compared to that of the cell with Nafion 117(0.790 V).From this study,it is concluded that a polymer electrolyte membrane suitable for proton exchange membrane fuel cell(PEMFC)and direct methanol fuel cell(DMFC)application can be obtained by blending SPSEBS and PVDF in appropriate proportions.The methanol permeability and selectivity showed a strong influence on DMFC performance.     

Design and In Vitro Evaluation of Solid-Lipid Nanoparticle Drug Delivery for Aceclofenac

Solid-lipid nanoparticles (SLNs) are an interesting nanoparticulate delivery system. The present work was carried out with the aim to develop a prolonged release solid-lipid nanoparticulate system for the drug using aceclofenac. Aceclofenac-loaded solid-lipid nanoparticles (ACSLNs) was prepared by hot high pressure homogenization technique. Tripalmitin was used as the lipid core. Surfactants (Poloxamer 188, Tween 80, and soya lecithin) and co-surfactant (sodium tauro glycholate) were used in the formulations. The prepared ACSLN formulations were characterized for encapsulation efficiency (EE), photon correlation spectroscopy (PCS), scanning electron microscopy (SEM), and x-ray diffraction (XRD). From these studies, mean particle diameter of the formulation prepared with combination of surfactants (Poloxmer 188 and Tween 80) was about 200 nm with spherical morphology and amorphous nature. Higher EE was obtained with SLNs prepared using combination of soya lecithin and poloxmer 188. The organization and distribution of the ingredients in the nanoparticulate system were studied by differential scanning calorimetry (DSC) and the results showed that the drug is incorporated into the solid matrix. The prepared formulations demonstrated favorable in vitro prolonged release characteristics. Experimental in vitro release data were substituted in available mathematical models to establish the release kinetics of ACSLNs and it was found to follow first-order kinetics and Higuchi diffusion mechanism. Our results suggest that these SLN formulations could constitute a promising approach for the drug delivery of aceclofenac.     

Enhanced Electrocatalytic Activity of Methanol and Ethanol Oxidation in Alkaline Medium at Bimetallic Nanoparticles Electrochemically Decorated Fullerene-C60 Nanocomposite Electrocatalyst: An Efficient Anode Material for Alcohol Fuel Cell Applications

Direct alcohol fuel cells (DAFCs) have been recently playing a pivotal role in electrochemical energy sources and portable electronics. Research in DAFCs has proceeded to engage major attention due to their high catalytic activity, long-term stability, portability, and low cost. Herein, we present a facile surfactant-free route to anchor bimetallic Pd−W nanoparticles supported fullerene-C₆₀ catalyst (Pd-W@Fullerene-C₆₀) for high-performance electrooxidation of alcohols (methanol & ethanol) for DAFCs applications. Structural, elemental composition, and morphological analysis of the proposed catalyst were carried out using UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy-dispersive x-ray spectroscopy (EDX). Electrochemical properties such as electrochemical activity, electrochemical active surface area (ECSA), and long-term stability of the Pd-W@Fullerene-C₆₀ catalyst for ethanol and methanol oxidation in the alkaline medium were explored by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). Results revealed that the proposed catalyst showed enlarged ECSA, tremendous electrocatalytic activity, high poison tolerance limit, good reproducibility, and enhanced long-term stability as compared to the monometallic catalyst and commercially available catalyst (Pt/C) towards ethanol and methanol oxidation reaction. This enhanced potentiality of the Pd-W@Fullerene-C₆₀ catalyst is due to the synergistic effect of W−Pd nanoparticles and excellent electron kinetic from fullerene support material. These findings strongly suggest the Pd-W@Fullerene-C₆₀ catalyst as potential anode material for the alcohol oxidation reaction.     

Iodine as a versatile catalyst for the hydroalkylation of vinyl arenes with 1,3-diketones

The vinyl arenes undergo smooth hydroalkylation with 1,3-diketones in the presence of 10 mol % of iodine to afford phenethyl diketones and ketoesters in good yields in short reaction times. The use of inexpensive and readily available molecular iodine makes this method quite simple, more convenient and practical.     

Magnetization and EPR of a series of Cr squarate dimers

A series of Cr(III) dimers were synthesized from a parent compound [Cr₂(μ-oxo)₂(μ_1,2-C₄O₄)₂(H₂O)₄]·2H₂O (I) by ligand substitution. The compounds have been analyzed using variable frequency EPR (9–110 GHz) and magnetic susceptibility as a function of field (0–9 T) and temperature (1.9–300 K) to obtain their electronic g-values, exchange energies, and zero-field parameters. The parent compound exhibits a broad maximum around 34 K characteristic of a dimer with antiferromagnetic coupling that fit the Van Vleck susceptibility model well. It was found that the maxima could be tuned from 34 to 80 K by ligand substitution of the waters. Each compound possesses a characteristic color spanning the range of teal to pink. The g-value of each compound was found to be ∼1.98 using spectral simulation. The DMSO derivative is water soluble and has a high LC₅₀ for PC3 cancer cells, suggesting its use as a magnetic resonance imaging agent. X-ray crystal structure of the DMSO derivative [Cr₂(μ-oxo)₂(μ_1,2-C₄O₄)₂(C₂H₆SO)₄]·2H₂O (II) revealed that the DMSO ligands are equatorial, and the squarate groups bridge the two chromiums. This is in contrast to the previously proposed structure of the parent compound where the water ligands were axial and the equatorial squarate groups did not bridge the chromiums. These compounds are interesting because of their ease of synthesis, and their wide range of magnetic behavior. The compounds are good probes into antiferromagnetic dimer exchange by controlling the ligand field surrounding the superexchange pathway present in the molecule.     

Kumada cross coupling reaction based synthesis,antimicrobial and computational studies of 6-aryl-2-phenyl-3-methylquinazolin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

Nickel catalyzed Kumada cross coupling reaction, a novel synthetic method for the synthesis of 6-aryl-2-phenyl-3-methylquinazolin-4(3H)-ones (6a–6i), was carried out by condensing 6-iodo-2-phenyl-3-methyl-quinazolin-4(3H)-one (4) with various 6-aryl/heteroaryl Grignard reagents. Molecular properties of compounds 4 and 6a–6i were studied using semiempirical PM3 computational method. The optimized geometry of the product 6 indicated that the aryl group at the position 6 was not coplanar with respect to either quinazolinone ring or phenyl group at 2 position. Compounds 6a–6i were screened for their activity against bacteria and fungi.     

Identification and quantification of alkene-based drilling fluids in crude oils by comprehensive two-dimensional gas chromatography with flame ionization detection

Comprehensive two-dimensional gas chromatography with flame ionization detection (GC x GC-FID) was used to measure alkene-based drilling fluids in crude oils. Compared to one-dimensional gas chromatography, GC x GC-FID is more robust for detecting alkenes due to the increased resolution afforded by second dimension separations. Using GC x GC-FID to analyze four oil samples from one reservoir contaminated with the same drilling fluid, C(15), C(16), C(17), C(18) and C(20) alkenes were identified. The drilling fluid that contaminated these samples also differed from another commercially obtained fluid, which only contained C(16) and C(18) alkenes. These results should motivate the petroleum industry to consider GC x GC-FID for measuring drilling fluids.