ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIncorporation of Nonionic Solutes into Aqueous Micelles: A Linear Solvation Free Energy Relationship AnalysisFrank H. Quina, Elena O. Alonso, and Joao P. S. FarahCite this: J. Phys. Chem. 1995, 99, 30, 11708–11714Publication Date (Print):July 1, 1995Publication History Published online1 May 2002Published inissue 1 July 1995https://pubs.acs.org/doi/10.1021/j100030a014https://doi.org/10.1021/j100030a014research-articleACS PublicationsRequest reuse...

Despite the intense interest in metabolic regulation and evolution of ATP-producing pathways, long standing question why most multicellular microorganisms metabolize glucose by respiration rather than fermentation remains unanswered. One such microorganism is cellulolytic fungus Trichoderma reesei (Hypocrea jecorina). Using EST analysis cDNA microarrays, we find that T. expression genes encoding enzymes tricarboxylic acid cycle proteins electron transport chain programmed a way favors...

Oxygen is essential for the survival of obligatorily aerobic eukaryotic microorganisms, such as multicellular fungus Trichoderma reesei. However, molecular basis inability cells to survive extended periods under anoxic conditions not fully understood. Using cDNA microarray analysis, we show that changes in oxygen availability have a drastic effect on gene expression T. The levels 392 (19.6%) out 2000 genes examined changed significantly response hypoxia, transient anoxia, and reoxygenation....

Fast calculation of charge distributions in molecules is feasible the electronegativity equalization method, EEM. Atomic electronegativities and hardnesses, fundamental parameters EEM, were obtained here by using CM1 atomic charges at semiempirical PM3 level as targets. A new optimization approach composed Genetic Simplex algorithms also described. The correlation between EEM improved considerably (correlation coefficient from 0.931 to 0.977, standard deviation 0.079 0.032 Fisher's F 31 627...

Abstract In this work the separation of eighteen flavonoids was attempted using reduced‐flow micellar elektrokinetic chromatography (RF‐MEKC) electrolytes modified by selected solvents with differing properties: methanol (MeOH), acetonitrile (ACN) and tetrahydrofuran (THF). Structural aspects such as unsaturation C ring, number position OH groups, methylation glycosylation well solvent effects their impact on electrophoretic behavior were addressed. By evaluating electropherograms obtained...

Abstract In this work, the separation of 11 natural and synthetic steroids was studied using MEKC electrolytes modified by property‐selected organic solvents: ethanol, ACN, THF. The interplay between electrophoretic behavior structural features disclosed effects modifiers to modulate retention alter selectivity were discussed in terms system linear solvation energy relationships (LSER). LSER indicated total solvent percentage electrolyte as a major parameter control minor contribution,...

The pH-independent hydrolysis of bis(2,4-dinitrophenyl) carbonate, DNPC, in aqueous acetonitrile was studied spectrophotometrically from 20 to 45 °C. binary solvent composition covers [H2O] 0.02 51.39 M, corresponding the water mole fraction, χw, 0.100 0.971. dependence log (kobs), observed rate constant, on χw is sigmoidal and similar polarity scale ET(30) for same mixture. As a function decreasing Gibbs free energy activation gradually increases, but ΔH⧧ ΔS⧧ show complex, quasi-mirror...

The electronegativity equalization methodology, EEM, is frequently used to calculate the charge distribution and reactivity index (e.g., local softness hardness, condensed Fukui function) of molecules. However, recent work (Chelli, R. et al., J. Chem. Phys. 1999, 111, 8569) has shown a serious shortcoming EEM in prediction polarizability for large In this paper, our goal show that we can obtain reliable dipole moment polypeptides vacuum continuum-dielectric solvent using constrained...

Incorporation coefficients for binding of 29 nonionic solutes to cationic/nonionic mixed micelles (1:1 molar ratio hexadecyltrimethylammonium bromide (CTAB)/ polyoxyethylene[23]dodecyl ether (Brij 35)) were employed establish a linear solvation free energy relationship (LSER) based on five solute parameters. Comparison this LSER with those incorporation into the pure, unmixed detergents indicates that hydrogen-bonding interactions are predominant contributors nonidealities solubilization in micelle.

The study of highly conjugated, carbonyl-containing molecules such as 1,4,5,8-naphthalene tetracarboxylic dianhydride, III, is interest since reactivity differences and transmission electronic effects through the conjugated framework can be evidenced. kinetics hydrolysis III in aqueous solution were determined from 5 M acid to pH 10. In basic yields, sequentially, diacid monoanhydride, II, acid, I. second order rate constant for alkaline 200 fold higher first ring opening. water-catalyzed...

Molecular modeling is growing as a research tool in Chemical Engineering studies, can be seen by simple on the latest publications field. investigations retrieve information properties often accessible only expensive and time-consuming experimental techniques, such those involved study of radical-based chain reactions. In this work, different quantum chemical techniques were used to phenol oxidation hydroxyl radicals Advanced Oxidation Processes for wastewater treatment. The results obtained...

Hydrolyses of benzaldehyde acetals, PhCH(OR)2, are specific hydrogen-ion catalyzed when R = methyl, n-butyl, but with secondary and tertiary alkyl derivatives, i-propyl, s-butyl, t-butyl, t-amyl, hydrolyses general-acid catalyzed. The Brønsted α values for both groups in the range: 0.57−0.61. A simple iterative procedure was developed to estimate individual rate constants catalysis by diacid monoacid forms succinic acid buffer. Plots log kobs (at [buffer] 0 M) against pH linear plots kH...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProton NMR study on the structure of water in Stern layer negatively charged micellesOmar A. El Seoud, Joao P. S. Farah, Paulo C. Vieira, and Monica I. SeoudCite this: J. Phys. Chem. 1987, 91, 11, 2950–2954Publication Date (Print):May 1, 1987Publication History Published online1 May 2002Published inissue 1 1987https://pubs.acs.org/doi/10.1021/j100295a060https://doi.org/10.1021/j100295a060research-articleACS PublicationsRequest reuse...

A parametrization of the polarizable continuum model (PCM) is presented having experimental hydration free energies 215 neutral molecules as target. The cavitation and dispersion contributions were based on Tuñon-Silla-Pascual-Ahuir (Tuñon; et al. Chem. Phys. Lett. 1993, 203, 289) Floris-Tomasi (Floris, F.; Tomasi, J. Comput. 1989, 10, 616) expressions, respectively. Both polar nonpolar evaluated same solvent-excluding molecular surface that used unscaled Bondi atomic radii. was provided for...

Abstract The chemical shift of water was measured as a function concentration the detergents cetyltrimethylammonium chloride. CTACl; 3‐N‐dodecyl‐N,N‐dimethylammonio‐1‐propanesulfonate, DDAPS; polyoxyethylene (9.5) octylphenyl ether, Triton X‐100, and deuterium content solvent. short chain compound butyltrimethylammonium bromide also studied model for CTACl. Graphs shifts vs. mole fractions solubilizates were linear in all cases slopes used to calculate so called “fractionation factor, ϕ”...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of the aminolysis and hydrolysis p-nitrophenyl carboxylates in presence dodecylammonium propionate aerosol-OT aggregates benzeneOmar A. El Seoud, Fatima Pivetta, Monica I. Joao P. S. Farah, Abilio MartinsCite this: J. Org. Chem. 1979, 44, 26, 4832–4836Publication Date (Print):December 1, 1979Publication History Published online1 May 2002Published inissue 1 December...

Abstract Kinetic and mechanistic details of the imidazole‐catalyzed hydrolysis substituted phenyl benzoates in 10% acetonitrile water (V/V) were examined. The following 4 ester series studied: p‐nitrophenyl p‐X‐benzoates (X = CH 3 , H, Cl, CN, NO 2 I), p‐Y‐phenyl p‐nitrobenzoates (Y II), 2, 4‐dinitrophenyl O, III) 2,4‐dinitrobenzoates IV). Based on: catalytic rate constants, activation parameters, kinetic solvent isotope effects, Hammett (δ) values spectroscopic detection reaction...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA proton magnetic resonance study of the deuterium-protium fractionation in aqueous solutions alkali-metal chloridesOmar A. El Seoud, Monica I. Paulo R. Pires, and Joao P. S. FarahCite this: J. Phys. Chem. 1984, 88, 12, 2669–2671Publication Date (Print):June 1, 1984Publication History Published online1 May 2002Published inissue 1 June 1984https://pubs.acs.org/doi/10.1021/j150656a047https://doi.org/10.1021/j150656a047research-articleACS...