Conductivities of (0.001-0.012) m sodium dodecyl sulfate have been determined in water and in the presence of 0.10 m aqueous glycine/alanine/glycylglycine at 298.15, 303.15, 308.15, and 313.15 K. From the specific conductivity data, the critical micellar concentration, degree of counter ion association, degree of counterion dissociation, free energy of transfer of hydrophobic chain from the medium to interior of the micelle, and surface contribution, standard free energy of micellization, standard enthalpy of micellization, and standard entropy of micellization of sodium dodecyl sulfate have been computed. The thermodynamic parameters of micellization and the effect of additives on these parameters have been used to study the interactions present in the micellar systems.
The apparent molar volumes (V 2 ) for glycine (Gly), l-alanine (Ala), phenylalanine (Phe), and glycylglycine (Gly-Gly) in 0.10 m aqueous d-galactose solutions have been determined from density measurements at (298.15, 303.15, 308.15, and 313.15) K. The data for (V 2 ) were utilized to estimate the partial molar volume at infinite dilution (V 0 2 ), and experimental slope (S * v ). The transfer volume, (V 0 2 (tr) ), and hydration number, (n H ) were also evaluated. The viscosity data were used to evaluate A-and B-coefficients of the Jones-Dole equation, the free energy of activation of viscous flow per mole of the solvent μ 0 * 1 and the solute μ 0 * 2 . The molar refractivity (R D ) was calculated from refractive index data. The results were discussed in terms of hydrophilic-ionic, hydrophilic-hydrophobic, and hydrophobic-hydrophobic interactions, and structure-making/-breaking ability of the solute (AAs/peptide) in aqueous d-galactose solutions.
Nanotechnology has become a promising approach and gain the appreciable recognition due to have biomedical application. Nanoparticles exhibited unique characteristic and play an effective role in area of science. The synthesis of nanoparticles with desire size and shape is an important field of research in nanotechnology. Herein we synthesized the zinc oxide nanoparticles (ZnO NPs) using zinc acetate as precursor and extract of waste strawberry extract as a reducing agent and stabilizing agent. Further, obtained ZnO NPs characterized by UV–vis, FTIR, EDX, XRD, and TEM analysis. The UV–vis result confirm ZnONPs formation with its surface Plasmon resonance peak (SPR) at 311 nm due to the collective oscillations of electrons in the conduction band in UV–vis spectra. XRD peaks also meet the standard of ZnONPs peaks and indicated that the prepared material consists of particles in nanoscale range. The SEM and TEM analyze the morphology, shape and size in range 50 nm with spherical shape. The FTIR was tested the functional group liable for the synthesis of ZnONPs. Graphical Abstract
The densities and viscosities of aqueous solution of cetyltrimethylammonium bromide (0.01 mol kg -1 ) (CTAB) and solutions of CTAB containing amino acids, viz., glycine, L serine, and L valine (0.01-0.05 mol kg -1 ), were determined in the temperature range 298.15-313.15 K. Apparent molar volumes of the amino acids were calculated from the density and viscosity values. The calculated apparent molar volumes were used to calculate standard partial molar volumes (V -2 0 ) and standard partial molar volumes of transfer of amino acids from water to an aqueous solution of CTAB. The viscosity values were used for the calculation of the viscosity coefficients A and B in the Jones-Dole equation. The linear dependences of V -2 0 and B on the number of carbon atoms in the alkyl chains of the amino acids were found. The results obtained were used in analysis of hydrophilic hydrophilic, hydrophilic hydrophobic, and hydro phobic hydrophobic interactions that occur during dissolution of amino acids in an aqueous solution of CTAB.Key words: amino acids, cetyltrimethylammonium bromide, standard partial molar vol ume, viscosity coefficients, hydrophobic hydrophobic interactions, hydrophilic hydrophobic interactions, hydrophilic hydrophilic interactions.The stable globular native conformation of proteins results from the delicate balance established due to inter actions between various groups in protein molecules. The character of these interactions depends on the pH of me dium, temperature, and the presence of low molecular weight substances, such as substrates, coenzymes, inhibi tors, and activators that specifically bind to the native structure. The interaction of surfactants with globular pro teins attracts much attention of researchers. 1-6 Studies of these interactions favor understanding the denaturation and solubilization action of surfactants on membrane pro teins and lipids. Since conformations and configurations of proteins are complicated, it is more convenient to study these processes in systems modeling proteins, for instance, in aqueous solutions of amino acids (AA) and aqueous solutions of CTAB.Surfactants at low concentrations in aqueous solutions behave much as normal electrolytes, but in more concen trated solutions they exhibit different behavior. Such be havior is due to the formation of aggregates consisting of many surfactant molecules. At specific concentration known as the critical micelle concentration (CMC), sur factant molecules undergo aggregation to form micelles. For CTAB, the CMC is achieved at 8.2•10 -4 mol L -1 (see Ref. 7). The physicochemical properties of surfactant so lutions differ noticeably in solutions with concentrations higher and lower than the CMC. 1,2 At concentrations be low the CMC, the physicochemical properties of ionic surfactants resemble those of strong electrolytes. At con centrations exceeding the CMC, the properties of surfac tants change considerably, indicating the formation of highly cooperative molecular associates.Volumetric measurements have been reported to be a sensit...
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