L-arginine In Water Research Articles

One-step Synthesis of Gold@Silica Yolk-shell Nanoparticles with Catalytic Activity

A one-step protocol for synthesizing Au@SiO2 yolk-shell nanoparticles (YSPs) from tetrachloroauric(III) acid (HAuCl4), tetramethyl orthosilicate (TMOS), and l-arginine in water is reported. Arginine, a basic amino acid, simultaneously reduces HAuCl4 to Au and catalyzes the reaction of TMOS to SiO2. The effects of HAuCl4, TMOS, and arginine on the morphology of YSPs are investigated. Time-course TEM analysis clarifies the formation process of the YSPs. The Au@SiO2 YSPs show good activity for the reduction of 4-nitrophenol.

Transformation of CSD When Crystal Shape Changes with Crystal Size into CLD from FBRM by Using Monte Carlo Analysis

In manufacturing process, it is necessary to measure change in CSD (Crystal Size Distribution) with time accurately because CSD is one of the most important indices that evaluate quality of products. FBRM (Focused Beam Reflectance Measurement) can measure CLD (Chord Length Distribution) in line, but CLD is different from CSD because of principle of FBRM. However, if CSD is determined beforehand, CLD can be calculated from the CSD with statistical method. First, when crystal shape is defined from the characteristic crystal size, the matrix of each crystal shape which transforms CSD into CLD in a uniform manner is calculated with Monte Carlo analysis. Characteristic crystal size is added to the variables defining chord length in order to avoid complex integrals and apply the change in crystal shape with characteristic crystal size to the transforming matrix. Secondly, CSD and CLD are actually measured in suspension of acetaminophen in ethanol and suspension of L-arginine in water to demonstrate the validity of 2 matrices. Lastly, these matrices are multiplied by some simple CSD models to test the properties of these matrices and demonstrate the utility of this transformation.

Solute–solute and solute–solvent interactions of l-histidine and l-arginine in aqueous-streptomycin sulphate solutions at different temperatures: A physicochemical study

The densities, ρ of l-histidine and l-arginine in water and in aqueous-streptomycin sulphate [1% (0.0069mol·kg−1) and 2% (0.0137mol·kg−1) streptomycin sulphate in water] mixed solvents were measured at temperatures 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15K; and ultrasonic speed, u and viscosities, η of these solutions were measured at temperatures 298.15, 303.15, 308.15, 313.15 and 318.15K and at atmospheric pressure. The ρ, u and η data have been used to calculate apparent molar volume, Vφ, limiting apparent molar volume, Vϕ°, apparent molar compressibility, Ks,ϕ, limiting apparent molar compressibility, Ks,ϕ°, transfer volume, Vϕ,tr°, transfer compressibility, Ks,ϕ,tr°, and partial molar expansibility, Eϕ°. The viscosity data have been used to determine Falkenhagen coefficient, A, Jones–Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#. The calculated parameters have been discussed in terms of various solute–solute and solute–solvent interactions prevailing in these solutions. The structure making/breaking ability of the amino acids in the aqueous-streptomycin sulphate solution is also discussed.

Probing solute–solute and solute–solvent interactions in (l-arginine + d-xylose/l-arabinose + water) solutions at different temperatures by using volumetric and viscometric methods

Densities, ρ of l-arginine in water and in aqueous–d-xylose/l-arabinose (2.5% and 5% of d-xylose/l-arabinose, w/w in water) mixed solvents were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15)K, and viscosities, η of these solutions at temperatures (298.15, 303.15, 308.15, 313.15 and 318.15)K were measured at atmospheric pressure. From the density values, the apparent molar volume, Vϕ, limiting apparent molar volume, Vϕ°, slope, Sv and transfer volume, Vϕ,tr° and hydration number, nH were calculated. The viscosity values have been analysed on the basis of the Jones–Dole equation; and Falkenhagen Coefficient, A and Jones–Dole coefficient, B were calculated. The Gibbs energies of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°# were also calculated. The results indicate that there exist strong solute–solvent interactions in these systems, which increase with increase in carbohydrate concentration in both the solvents. It is observed that l-arginine act as a structure-maker in both these solvent systems.

Volumetric Behavior on Interactions of α-Amino Acids with Sodium Acetate, Potassium Acetate, and Calcium Acetate in Aqueous Solutions

The apparent molar volumes (VΦ) of l-lysine monohydrochloride, l-histidine, and l-arginine in water and in aqueous of sodium acetate, potassium acetate, and calcium acetate solutions have been determined at temperatures from (303.15 to 323.15) K from density measurements. The partial molar volumes at infinite dilution (Vo2) obtained from VΦ data have been used to calculate the transfer volume (ΔVtr) of amino acids in water and in the presence of the cosolutes at different temperatures. These parameters have been discussed in terms of various interactions between the α-amino acids and organic salts in these solutions. The dehydration effect of sodium, potassium, and calcium acetates has also been discussed.

Volumetric Investigations on Interactions of Acidic/Basic Amino Acids with Sodium Acetate, Sodium Propionate and Sodium Butyrate in Aqueous Solutions

The apparent molar volumes, V φ , of L-aspartic acid, L-glutamic acid, L-lysine monohydrate and L-arginine in water and in aqueous (0.1, 0.25, 0.5 and 1.0) mol⋅kg−1 sodium acetate and sodium propionate, and (0.1, 0.25 and 0.5) mol⋅kg−1 sodium butyrate solutions have been determined at 288.15, 298.15, 308.15 and 318.15 K from density measurements. The partial molar volumes at infinite dilution, V 2 o , obtained from V φ data, have been used to calculate hydration numbers and partial molar expansibilities of amino acids in water and in the presence of the studied cosolutes at different temperatures. These parameters have been discussed in terms of various interactions between the acidic/basic amino acids and organic salts in these solutions. The effect of the hydrophobic chain length of the carboxylate ions has also been discussed.