Mutual solubilities of hydrocarbons and water with the CPA EoS

The knowledge of hydrocarbon/water phase equilibria is important in the design and operation of equipment for petroleum transport and refining and petrochemical plants. The presence of water in a hydrocarbon mixture can affect the product quality and damage the operation equipment due to corrosion and formation of gas hydrates. Tracing the concentration of hydrocarbons in aqueous media is also important for technical purposes like preventing oil spills and for ecological concerns such as predicting the fate of these organic pollutants in the environment.     

Direct determination of glyphosate using hydrophilic interaction chromatography with coulometric detection at copper microelectrode

A simple, rapid, and low-cost coulometric method for direct detection of glyphosate using hydrophilic interaction chromatography is presented. The principle of detection is based on the enhancement of the anodic current of copper microelectrode in the presence of complexing agents, such as glyphosate, with the formation of a soluble Cu(II) complex. Under optimized conditions, the limit of detection (S/R = 3) for glyphosate was 0.1 mg L⁻¹ (0.59 μM) without any preconcentration method. The calibration curve has been found linear in all concentration range tested (from limit of detection to 34 mg L⁻¹) with an excellent correlation coefficient (0.9999). The present method was successfully applied for the determination of glyphosate in fruit juices without any kind of extraction, clean-up, or preconcentration step, with recoveries of 92 and 90% for apple and grape juice, respectively.     

Improvement of permanent memory effect in PDLC films using TX-100 as an additive

A number of polymer dispersed liquid crystal (PDLC) films based on dimethacrylate monomers were synthesised by polymer-induced phase separation (PIPS) using polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether (TX-100) as an additive up to total solution weight of 10% aiming to modify the initial anchorage force of the liquid crystal (LC) molecules to the polymeric matrix. The effects of the addition of this additive to the PDLC films were studied resorting to electro-optical studies. Using a fitting model, several parameters were correlated such as the permanent memory effect (PME), the voltage required to achieve 90% of maximum transmittance (E90), the average elastic constant (K) and the rotational viscosity of the director (γ). The use of TX-100 results on an increase on the PME and γ, and decrease on the E90 and K.     

Molecular modeling studies, synthesis, and biological evaluation of Plasmodium falciparum enoyl-acyl carrier protein reductase (PfENR) inhibitors

The search for new antimalarial agents is necessary as current drugs in the market become vulnerable due to the emergence of resistance strains of Plasmodium falciparum (P. falciparum). The biosynthetic pathway for fatty acids has been recognized and validated as an important drug target in P.falciparum. One of the important enzymes in this pathway that has a determinant role in completing the cycles of chain elongation is Enoyl-ACP reductase (ENR) also popularly known as FabI. In this paper we report the design, synthesis, and microbial evaluation of inhibitors of Plasmodium enoyl reductase (PfENR). The search for inhibitors involved a virtual screening of the iResearch database with docking simulations. One of the hits was selected and modified to optimize its binding to PfENR; this resulted in the development of analogues of N-benzylidene-4-phenyl-1,3-thiazol-2-amine. The activity of these analogues was predicted from comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models constructed from a dataset of 43 known inhibitors of PfENR. The most promising molecules were synthesized and their structures characterized by spectroscopic techniques. The molecules were screened for in vitro antimalarial activity by whole-cell assay method. Two molecules, viz. VRC-007 and VRC-009, were found to be active at 4.67 and 7.01 μM concentrations, respectively.