Search

In this work, we studied TEMPO-oxidized cellulose nanofibril (OCNF) suspensions in the presence of diverse surfactants. Using a combination of small angle neutron scattering (SANS) and rheology, we compared the physical properties of the suspensions with their structural behavior. Four surfactants were studied, all with the same hydrophobic tail length but different headgroups: hexaethylene glycol mono-n-dodecyl ether (C12EO6, nonionic), sodium dodecyl sulfate (SDS, anionic), cocamidopropyl betaine (CapB, zwitterionic), and dodecyltrimethylammonium bromide (DTAB, cationic). Contrast variation SANS studies using deuterated version of C12EO6 or SDS, or by varying the D2O/H2O ratio of the suspensions (with CapB), allowed focusing only on the structural properties of OCNFs or surfactant micelles. We showed that, in the concentration range studied, for C12EO6, although the nanofibrils are concentrated thanks to an excluded volume effect observed in SANS, the rheological properties of the suspensions are not affected. Addition of SDS or CapB induces gelation for surfactant concentrations superior to the critical micellar concentration (CMC). SANS results show that attractive interactions between OCNFs arise in the presence of these anionic or zwitterionic surfactants, hinting at depletion attraction as the main mechanism of gelation. Finally, addition of small amounts of DTAB (below the CMC) allows formation of a tough gel by adsorbing onto the OCNF surface. [ABSTRACT FROM AUTHOR]

In this study, we investigated the solubility of coumarin in aqueous solution and binary mixtures of N,N-dimethylformamide (DMF), acetonitrile (ACN), and dimethylsulfoxide (DMSO) through experimental measurements. The solubility experiments were carried out using the analytical technique of UV-Vis spectroscopy in a temperature range of 288.15–308.15 K under atmospheric pressure using a digital temperature controlling thermostat. Water–DMF mixture system exhibited the highest solubility of coumarin, whereas water–ACN system showed the lowest solubility among the studied solvent systems. To gain a deeper understanding of the solvation process, we employed theoretical studies to optimize the molecular structure of the compound. This optimization enabled the calculation of significant molecular properties, such as close molecular dimension and dipole moment, which play key roles in determining various thermodynamic parameters associated with solvation. By utilizing the measured solubilities, we analyzed the thermodynamic properties of coumarin dissolution, including the Gibbs free energies of the solutions, transfer Gibbs free energies related to cavity formation and dipole–dipole interactions, transfer enthalpy of dissolution, and chemical transfer energetics. These analyses aimed to provide insights into the thermodynamic stability of coumarin-like compounds in solution. [ABSTRACT FROM AUTHOR]

Today, CO2 separation is very important, both as an environmental issue and also in various industries. In this study, the water‐based nanofluid of NaP zeolite nanocrystals and 1‐dodecyl‐3‐methylimidazolium chloride ([C12mim][Cl]) ionic liquid were mixed and tested experimentally for CO2 absorption in an isothermal high pressure cell equipped with magnetic stirring. Zeolite nanocrystals were synthesized via the hydrothermal approach and characterized. A series of experiments were performed at different conditions to investigate the impact of various parameters, including nanoparticle type, nanoparticle concentration, stabilizer concentration, and the vessel's initial pressure, on CO2 solubility. It was found that 0.02 wt.% of zeolite nanoparticles, 0.4 wt.% of [C12mim][Cl] ionic liquid, and 0.05 wt.% of sodium dodecyl benzene sulphonate (SDBS) in nanofluids result in higher absorption of CO2 compared to other concentrations. Furthermore, CO2 absorption was increased by increasing ionic liquid and surfactant concentration up to a certain value near critical micelle concentration, but after that the CO2 absorption was decreased. The overall CO2 absorption enhancement at 20 bar for 0.02 wt.% zeolite and ZnO water‐based nanofluids with 0.4% [C12mim][Cl] ionic liquid and 0.02 wt.% SDBS were 26.9%, 21.5%, 21.2%, and 17% in comparison to pure water, respectively. In an absorption process using nanofluids, besides the influence of the mentioned parameters, the micro‐convection caused by Brownian motion and the grazing effect of nanoparticles should be noted. Considering the micro‐convection and grazing effects, a theoretical model should take into account the Brownian motion and grazing effects on the mass transfer rate in nanofluids to investigate the absorption enhancement by nano‐particles. [ABSTRACT FROM AUTHOR]

In this study, we report a simple technique for the pyrofabrication of a novel photocatalyst of titanium dioxide quantum dots‐kaolinite nanocomposite (TiO2‐QDs‐Kao) used for rhodamine B (RhB) dye degradation. The photocatalyst was characterized by using different analytical techniques, including XRD, XRF, XPS, FTIR, DTA/TGA, SEM–EDX, TEM, BET, BJH, ZP and UV–Vis DRS. The photocatalytic degradation of RhB was performed in aqueous solutions using the sustainable sunlight energy under atmospheric conditions and fixed neutral medium (pH = 7). The produced photocatalyst exhibited optical band gap energy of 2.85 eV, an improved large specific surface area of 107.724 m2/g with pore radius of 1.45 nm and total pore volume of 0.123 cm3/g. The study indicated a maximum 91% degradation efficiency of RhB after 120 min using the optimum dose 1,400 mg/l of the TiO2‐QDs‐Kao photocatalyst. The degradation of RhB dye fitted the Langmuir first‐order kinetics with rate constant 0.0151 min−1. The radical trapping experiments based on scavengers confirmed that the mechanism of photocatalytic degradation activity was potentially based on electron (e−) and hole (h+) conduction band. The potential energy of the valence and conduction bands EVB and ECB were calculated 2.73 and −0.12 eV, respectively. A triple reusability study confirmed a high stability of TiO2‐QDs‐Kao photocatalyst with detected degradation efficiencies of 91.0, 89.9, 88.8 and 87.5%, respectively. [ABSTRACT FROM AUTHOR]

A new coordination complex of [Cd (2,2′‐bipyridine)(dipic) (H2O)2]. 7H2O (dipic2− = pyridine 2,6‐dicarboxylate) was synthesized under hydrothermal conditions. The crystal structure of Cd complex was characterized by X‐ray diffraction. The results confirmed that the coordination geometry of Cd2+ is a distorted pentagonal bipyramid. The complex was evaluated as a catalyst for the peroxidation of cyclohexane. The oxidation reaction was performed under mild conditions by hydrogen peroxide at room temperature. In the absence of HNO3, Cd complex exhibits a maximum yield of 31%. CdO nanoparticles were synthesized through thermal analysis of Cd complex and identified by various techniques. The ability of CdO nanoparticles was investigated for the removal of Congo red (CR). The effects of contact time, adsorbent dosage, and pH were evaluated using batch method. Studies have shown that the uptake process is pseudo‐second order. Also, the adsorption isotherm can be well fitted by the Langmuir model, while this process is spontaneous. [ABSTRACT FROM AUTHOR]

Three nitrogen‐heterocyclic nicotinonitriles compounds 4, 6‐dimethyl‐2‐(methylamino)‐nicotinonitrile 3; 2‐(dimethylamino)‐4, 6‐dimethyl‐nicotinonitrile 4, 2‐((3‐bromophenyl)‐amino)‐4, 6‐dimethyl‐nicotinonitrile 5 are prepared and characterized by Fourier transformer infra‐red spectroscopy, proton nuclear magnetic resonance, mass spectrometry and elemental analysis. Novelty of study is synthesis and evaluation of new series organic compounds of related chemical structures as corrosion inhibitors acid pickling of brass alloy by nitric acid. Compound 5 is prepared for the first time. Compounds 3–5 are potent biocides and efficient corrosion inhibitors for brass alloy. Inhibition efficiency 94 %, 95 %, 96 % are achieved at 180 ppm compounds 3–5, respectively. Inhibition efficiency followed the order: compound 5>4>3. For compound 5, increase charge transfer resistance and decrease in capacitance of electrical double layer confirmed adsorption mechanism. Limiting current indicated that corrosion is controlled by mass transfer of oxygen toward metal surface. Inhibition efficiency followed quantitative structure activity relationships. For the same molecular chemical structure of nicotinonitriles compounds 3–5, Substituents methylamino, dimethylamino and 3‐bromophenylamino increased inhibition efficiency following the order: 3‐Br‐C6 H4 NH>(CH3)2 N>CH3NH. [ABSTRACT FROM AUTHOR]

5‐hydroxymethylfurfural (HMF) is one of the most valuable biomass platform molecules, enabling the construction of a plethora of high value‐added furanic compounds. In particular, in the last decade, HMF has been considered as a starting material for designing biobased surfactants, not only because of its renewability and carbon footprint, but also because of its enhanced biodegradability. This Review presents recent examples of the different approaches to link the hydrophilic and lipophilic moieties into the hydrophobic furan (and tetrahydrofuran) ring, giving a variety of biobased surfactants that have been classified here according to the charge of the head polar group. Moreover, strategies for the synthesis of different non‐furanic structures surfactant molecules (such as levulinic acid, cyclopentanols, and aromatics) derived from HMF are described. The new HMF‐based amphiphilic molecules presented here cover a wide range of hydrophilic‐lipophilic balance values and have suitable surfactant properties such as surface tension activity and critical micelle concentration, to be an important alternative for the replacement of non‐sustainable surfactants. [ABSTRACT FROM AUTHOR]

Conductance has been measured in 60% DMSO-water mixture at various concentration in the temperature range 298-313K. The limiting molar conductance (λ0 m), degree of dissociation (a), dissociation constant (Kd), Walden constant, energy of activation and thermodynamic parameters are evaluated. The results obtained have been interpreted in terms of molecular interactions and solvent properties. [ABSTRACT FROM AUTHOR]

A new pyrazole derivatives azo dye 1-(3-phenyl-5-Pyrazolylazo)-R acid (L1) and 5-(3-phenyl-5-Pyrazolylazo)-8-hydroxy quinoline (L2) was synthesized. The acid–base equilibrium, ionization constants, the effect of pH and some organic solvents on the spectra of ligands, the chromogenic reaction and the stability constant of Co+2, Cu+2,Ni+2 and Zn+2 ion complexes with ligands were studied and determined spectrophotometrically and conductometrically. The optimum pH was determined for the ligands and the complexes. 2:1 and 1:1 (L:M) stoichiometric complexes have been formed in solutions. The stability constants order of the under study complexes was Co+2 < Ni+2 < Cu+2. These metal ions were determined using the ligands as indicators. The reagents can be also useful to use as indicators in acid–base titrations as confirmed experimentally. [ABSTRACT FROM AUTHOR]

Ethanol is a common protein crystallization agent, precipitant, and denaturant, but also alters the dielectric properties of solutions. While ethanol-induced unfolding is largely ascribed to its hydrophobic parts, its effect on protein phase separation and inter-protein interactions remains poorly understood. Here, the effects of ethanol and NaCl on the phase behavior and interactions of protein solutions are studied in terms of the metastable liquid–liquid phase separation (LLPS) and the second virial coefficient B2 using lysozyme solutions. Determination of the phase diagrams shows that the cloud-point temperatures are reduced and raised by the addition of ethanol and salt, respectively. The observed trends can be explained using the extended law of corresponding states as changes of B2. The results for B2 agree quantitatively with those of static light scattering and small-angle X-ray scattering experiments. Furthermore, B2 values calculated based on inter-protein interactions described by the Derjaguin-Landau-Verwey-Overbeek (DLVO) potential and considering the dielectric solution properties and electrostatic screening due to the ethanol and salt content quantitatively agree with the experimentally observed B2 values. [ABSTRACT FROM AUTHOR]

We describe here a method to synthesize ultrasmall nanocapsules with a diameter of 6 nm, exhibiting a well‐defined core–shell morphology. Remarkably, the nanocapules are synthesized in a miniemulsion process without the need of large amounts of surfactant as commonly used in the microemulsion process. Ultrasmall nanocapsules with an oil core and a silica shell are formed by the concurrent processes of a sol–gel reaction and Ostwald ripening. Using solvents with different water solubilities and alkoxysilanes with different reactivities, we demonstrate that sizes of obtained nanocapsules depend on the ripening rate and alkoxysilane conversion rate. The method can be also used for encapsulating natural oils such as peppermint oil and limonene. This work shows that the Ostwald ripening phenomenon can be employed beneficially for the preparation of very small colloids. [ABSTRACT FROM AUTHOR]

The effect of Fagonia arabica as corrosion inhibitor for Cu in nitric acid solution was studied utilizing mass loss technique, potentiodynamic polarization measurement, electrochemical impedance spectroscopy method, and scanning electron microscopy (SEM); the inhibition efficiency was found to increase with increase in the concentration of inhibitor; the inhibitive effect of this inhibitor was explained based on adsorption metal surface, the adsorption effect follows Flory‐Huggins adsorption isotherm. The corrosion rate was calculated; the results revealed that F. arabica has good inhibition effect on Cu. The surface morphology of Cu metal was examined by employing various techniques such as atomic force microscopy (AFM) and SEM. The AFM results observed greater inhibition efficiency of F. arabica for Cu dissolution in the acid corrosive environment. The parameters for the corrosion procedure have also been determined and discussed. [ABSTRACT FROM AUTHOR]

The thermodynamics of solute–solvent interactions associated with solvation phenomena were estimated for solutions of glycine, DL-alanine, DL-norvaline and DL-serine. Initially, Gibbs free energies of transfer from water to water-sodium iodide mixtures were determined from solubility data. The equilibrium solubilities of amino acids in water and aqueous sodium iodide solution at standard temperature T = 298.15 K were evaluated via formol titration. Various important physicochemical factors like enthalpy, free energy, molar volume, molar mass, etc. in aqueous sodium iodide solution were measured at standard temperature. The thermodynamic parameters were used to analyze the virtual stability of the zwitterionic solutes in aqueous sodium iodide solution. The factors associated with solubility were also explained and interrelated with physical and thermodynamic aspects. [ABSTRACT FROM AUTHOR]

Single crystal X-ray structurally characterized azo-uracil derivative (L) is explored for the selective detection of pyrene via aggregation-induced emission (AIE) with 99-fold fluorescence enhancement. In the presence of pyrene, non-fluorescent L emits green light and allows pyrene detection to as low as 3.6 × 10−9 M. Three model probes (L1, L2 and L3) were employed to support the proposed sensing mechanism. Further, silica-immobilized L efficiently removes pyrene from its reservoir. [ABSTRACT FROM AUTHOR]

Proceeding from the view concerning the environmental safety, the green synthesis approach was implemented in this study to synthesize new Schiff base complexes. All compounds were characterized by spectroscopic, analytical and theoretical techniques. Octahedral configuration was proposed for all complexes except Pd(II) one which has square‐planer geometry. The ligand coordinated towards metal ions through bi‐dentate or tri‐dentate in mono‐negative or neutral state. DFT method in material studio package, was used to optimize structural forms for most compounds. Conductometric titrations were carried out for Cu(II) and Ni(II) ions to estimate association and formation constants in solutions at presence or absence of H2L ligand. Hirshfeld surface properties were estimated by using Crystal explorer 3.1 program. The data proposed well molecular packing in crystal systems of Pd(II) and Co(II) complexes. Drug‐likeness study as well as MOE‐docking simulation were done to put an expectation for biological efficiency, which point to the priority of the ligand and its Pd(II) and Zn(II) complexes. Prolonged biological screening was made to evaluate the effectiveness of all new compounds in comparing to standard drugs. The ligand and its Zn(II) complex were the most effective compounds towards variable microbes, free radical producers and colorectal carcinoma cells lines. [ABSTRACT FROM AUTHOR]

Cadmium nanoparticles (Cd-NPs) were synthesized at room temperature using Moringa oleifera plant extract as a natural reducer and stabilizer agent. Cd-NPs were characterized using adsorption/desorption, Fourier-transform infrared (FTIR) spectroscopy, UV–visible spectrophotometry, photoluminescence, x-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX) and differential scanning calorimetry (DSC) thermal analysis. Adsorption and desorption studies shows that Cd-NPs have a stable adsorption. The FTIR studies also confirm that the Cd-NPs coated by the organic compounds are present in the Moringa extract. XRD pattern demonstrates that amorphous and crystalline phases coexist in Cd-NPs of hexagonal structure. SEM and TEM observations also show the formation of Cd-NPs with an average size of 30–40 nm. EDX analysis reveals that the nanocomposite contains 29.85% carbon, 37.97% oxygen 27.04% cadmium, 4.41% phosphorus and 0.73 potassium. DSC analysis shows the thermal behavior of Cd-NPs. [ABSTRACT FROM AUTHOR]

The effect of gamma-rays on structural, optical and photocatalytic properties of TiO2 nanoparticles under controlled atmospheres are studied to further improve photocatalytic performance. The sol–gel TiO2 powders were deposited with spin-coating technique, annealed at 500°C then finally irradiated by gamma-rays. The structural and optical characteristics of samples were investigated by Fourier transform infrared spectroscopy, x-ray diffraction and UV-visible spectroscopy (UV). The time-dependent density functional theory (TD-DFT) calculation are used to determine ground geometries and electronic structures of TiO2 nanostructures. DFT calculations present an excellent conformity with experimental results, and a high anisotropy in stretched thermal and electrical conductivity TiO2 nanostructures was found. Structural and optical results show that gamma radiation did not change the crystallinity of TiO2 nanostructures and leads to an optical band gap reduction to 3.039 eV. The gamma radiation effect on photocatalytic performance was investigated by methylene blue degradation as a typical pollutant. Gamma radiation has been discovered to improve considerably the degradation of pollutants compared with unirradiated TiO2. [ABSTRACT FROM AUTHOR]

In this study, the inhibition effect of Tamarix Boveana (TB) extract on Cu corrosion in 1 mol L–1 (HNO3 + H3PO4) mixture was studied. Electrochemical techniques such as (potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM)) and non-electrochemical technique such as mass loss were used. Results showed that TB extract has good inhibition efficiency (IE), follows Langmuir adsorption isotherm and all of the methods are in good agreement. The IE increased by increasing the concentration of the extract and decreased by increasing the temperature so, the extract adsorbed on Cu surface physically. The IE depends on the concentration of the extract and reaches 73.5% at 300 ppm of the extract. PP results revealed that the (TB) extract doings as mixed type one. Surface analysis revealed that the extract components are adsorbed on Cu surface forming a film. [ABSTRACT FROM AUTHOR]

In this study the physicochemical interactions of acefylline piperazine drug (APD) were examined in aqueous and aqueous polymer systems viz., aqueous polyethylene glycol (1.0 %w/v) and aqueous polyvinyl pyrrolidone (1.0% w/v). The study was carried within the concentration ranges from 2.0×10-2 to 10.0 ×10-2 mol/dm3 at different temperatures (293.15 to 318.15 K with the difference of 5 K). Various analytical methods such as conductometric, refractometry, and liquid chromatographic (RP-HPLC) were applied. In order to observe the interaction of APD, o m was calculated to evaluate the structural influence of polymers on the mobility of solute (APD) at different temperatures. α, Kd and Walden product of APD were also assessed in aqueous polyethylene glycol and aqueous polyvinyl pyrrolidone. Solvation was observed by Walden's product showing strong solvation of APD in water-soluble polymer systems. Thermodynamic parameters for APD such as E* α , ΔG* , ΔH* and ΔS* have also been evaluated as a function of temperature to determine the exo/endothermic nature of the drug dissociation process. Specific refraction, molar refraction and polarizability of APD in aqueous and aqueous polymer systems were calculated using the Lorentz-Lorentz equation and various interactions were interpreted. Drug's compatibility studies were also performed by HPLC in aqueous and aqueous polymer systems. [ABSTRACT FROM AUTHOR]

The complexation of 3-substituted-2-(aryl-,methyl)sulfonylamino-4,5,6,7-tetrahydrobenzo[ b]thiophenes with Cu(II), Co(II), and Ni(II) ions in ammonia media was studied. Different types of complexes with Cu(II) ions were found depending on pH: with a ratio of 1: 2 at pH of ~4-5 and 1: 1 at pH of ~ 8-10. For the Co(II) and Ni(II) ions, the formation of 1: 1 complexes at pH of ~9-10 was established. The Cu(II), Co(II), and Ni(II) complexes [Cu(HL)2. 2H2O] and [ML. 2H2O] were separated and identified, and their solubility products were calculated. The effect of the nature of the functional group in the third position of the thiophene ring on the properties of the complexes of reagents with nonferrous metal ions was shown. [ABSTRACT FROM AUTHOR]

The corrosion performance of α-brass in 1 M HNO3 and in the presence of polyethylene glycol (PEG) has been investigated using AC impedance spectra (EIS), potentiodynamic polarization (PP), electrochemical frequency modulation (EFM), and mass reduction (MR) techniques. The outcome data of EIS showed a rise in the resistance charge transfer (Rct) and a decrease in the capacitance double layer (Cdl). Protection efficiency (IE) of PEG has been obtained by varying the dose of the PEG and temperature. PEG adsorbed on α-brass in acidic solution follows isotherm Langmuir. The polarization curves displayed that PEG acts as a mixed-kind inhibitor. The parameters obtained from thermodynamic activation of corrosion α-brass in 1 M HNO3 were obtained and debated. The results obtained from all tests were in excellent agreement. [ABSTRACT FROM AUTHOR]

Poly o-aminophenol (POAP) was prepared by the oxidative polymerization of o-aminophenol with potassium dichromate as an oxidant. The results showed that o-amniophenol polymerizes in linear mode. The effect of doping CoCl, NiCl MnCl, FeCl, and CuCl on the spectral, thermal and optical properties of POAP has been studied. The thermal stability of doped POAP differs from the pure POAP according to the doped ion. The optical band gaps of the doped POAP are smaller than the pure POAP. Fe doped POAP has been used as a precursor for hematite (α-FeO) nanoparticles by thermal decomposition route. The obtained (α-FeO) nanoparticles have been characterized by XRD and HRTEM. The average size of the prepared nanoparticles was estimated as 53 nm. The optical band gap of the obtained α-FeO is larger than the bulk. [ABSTRACT FROM AUTHOR]

The design of micro-optical resonator arrays are introduced and tailored towards refractive index sensing applications, building on the previously unexplored benefits of open dielectric stacks. The resonant coupling of identical hollow cavities present strong and narrow spectral resonance bands beyond that available with a single Fabry Perot interferometer. Femtosecond laser irradiation with selective chemical etching is applied to precisely fabricate stacked and waveguide-coupled open resonators into fused silica, taking advantage of small 12 nm rms surface roughness made available by the self-alignment of nanograting planes. Refractive index sensing of methanolwater solutions confirm a very attractive sensing resolution of 6.5 × 10-5 RIU. Such high finesse optical elements open a new realm of optofluidic sensing and integrated optical circuit concepts for detecting minute changes in sample properties against a control solution that may find importance in chemical and biological sensors, telecom sensing networks, biomedical probes, and low-cost health care products. [ABSTRACT FROM AUTHOR]

Densities $$\rho $$ and ultrasonic speeds u for pure diethylene glycol, 1-butanol, 2-butanol, and 1,4-butanediol and for their binary mixtures over the entire composition range were measured at 298.15 K, 303.15 K, 308.15 K, and 313.15 K. Using these data, the excess molar volumes, $$V^{E}_\mathrm{m}$$ , deviations in isentropic compressibilities, $${\varDelta }k_{s}$$ , apparent molar volumes, $$V_{\phi ,i} $$ , partial molar volumes, $$\overline{V}_{m,i} $$ , and excess partial molar volumes, $$\overline{V}_{m,i}^E $$ , have been calculated over the entire composition range, and also the excess partial molar volumes of the components at infinite dilution, $$\overline{V}_{m,i}^{E,\infty }$$ have been calculated. The excess functions have been correlated using the Redlich-Kister equation at different temperatures. The variations of these derived parameters with composition and temperature are presented graphically. [ABSTRACT FROM AUTHOR]

The densities of glycyl-glycine (diglycine) and glycyl- l-leucine, in water and in aqueous sodium acetate, potassium acetate, magnesium acetate and calcium acetate solutions, were measured at 298.15 K. The apparent molar volumes, V, and the partial molar volumes, $$ \bar{V}_{1} $$ , of diglycine and glycyl- l-leucine have been calculated. The solvation number, n, of diglycine was also calculated. The limiting apparent molar volumes of the studied peptides were also analyzed in terms of the Setschenow relationship. The effect of the acetate salt solutions on the volumetric properties of the studied peptides was also discussed in terms of the Setschenow coefficients, k. The results indicate that the limiting apparent molar volume in aqueous acetate solutions is higher than that in water and the values increase with the concentration of the co-solutes (NaA, KA, MgA and CaA). The results indicate that the peptide interactions are stronger with MgA/CaA than NaA/KA. Also the data suggest that the peptide interactions are stronger with NaA than KA and with MgA than CaA. Further, the limiting apparent molar volume values increase from diglycine to glycyl- l-leucine. It was also noted that the solvation numbers for the diglycine in aqueous acetate salt solutions are less than in water and decrease as the concentration of acetate salt increases. [ABSTRACT FROM AUTHOR]