Papers by Keyword: Partition Coefficient

Abstract: Discussed with the method of the aqueous two-phase extraction of grape seed procyanidins optimum extraction conditions and extraction efficiency. Methods: Procyanidins extraction experimental conditions were optimized with the single, calculate the content and extraction rate of procyanidins from grape seeds with catechin standard curve comparison method. Results: Experiments show that: aqueous two-phase systems are made up of water 3.0 mL, ethanol 3.5 mL, ammonium sulfate 2.5 g, grape seed 0.5 g, centrifuged 10 min at 3600 r/min speed, placed 120 minutes, procyanidins at a rate of 0.23%, extraction rate reached 97.86%. Conclusions: This aqueous two-phase systems extraction rate, simple operation, environmental conservation, conditions required in practical applications easily met.

Abstract: Monomers used in dentistry allow tackling shrinkage problem during polymerization of dental composites.These monomers may cross biomembranes, a phenomenon that can lead to various toxic responses. An important factor that express the lipophilicity of these compounds is the partition coefficient. This parameter allows assessment of the solubility of a monomer to another and, generally, of a material to another.Computational partition coefficients study of water / octanol for a series of monomeric compounds analyzed showed the contribution of chemical structures dependent descriptors of substances on this parameter. The purpose of the assessment of these molecular descriptors is to show their importance in the partition of the substances studied in two phases aqueous and lipid (n-octanol).This allows optimization of the action of compounds activity very useful in finding new monomers used in dental reconstruction.

Abstract: An investigation on the migration of various migrants from paper (board) into solid food simulants was undertaken to determine the correlation of partition coefficients between food simulants / paper, K_F,P, and octanol/water, K_O,W. The migration tests were carried out using four solid food simulants (rice powder, milk powder, white sugar and rice) in contact with a kind paper which was spiked with 5 compounds. These model migrants cover a wide range of potential migrants in paper (board) food packaging materials and can be characterized by octanol/water partition coefficients ranging from log K_O,W = 2.293 to 4.496. In all simulants a correlation of increasing log K_{O, W} with increasing log K_F,P was found. Using the correlation line as a calibration curve, log K_{F, P} can be predicted from the log K_{O, W} values of the migrants for a given food stimulant. This approach is a new estimation procedure to obtain K_{F, P} values from easily accessible K_O,W values which can significantly reduce the efforts for compliance assessment by minimizing time and costs to be spent compared to carrying out an enormous number of specific migration test. Furthermore, this approach will support experimental migration testing since it provides a method to determine which simulant is appropriate for a given foodstuff.

Abstract: The potential of aqueous two phase extraction for the isolation and purification of flavonoids from Artemisia argyi leaves is investigated. Influence of the process parameters such as type of phase forming salts, concentration of salt and ethanol, added salt and temperature was studied. 30% ethanol/18.87% (NH4)2SO4 system was found most suitable for the extraction. The ethanol and salt concentration were found to significantly affect the flavonoids recovery and partition coefficients. The recovery of 93.16% was obtained at the selected process conditions. The results demonstrated the feasibility of aqueous two phase extraction for the isolation and purification of flavonoids.

Abstract: Three different kinds of imidazoline quaternary ammonium salts were synthesized with the use of valeric acid, decanoic acid, oleic acid, diethylenetriamine, benzyl chloride and thiourea as raw materials. The corrosion inhibition performances on carbon steel in HCl solution were measured via static weight loss method and polarization curve method. Partition coefficients in water and oil were measured, from which thermodynamic parameters of G_0→w、ΔS_0→w and ΔH_0→w were obtained. Temperature effect on the mass transfer between water and oil were examined.Corrosion inhibitor protection is an effective solution to oil field corrosion problems in the acidification process [1]. Most organic inhibitor molecules contain lone pair electrons and rich π-electron such as O, N, S, P atoms or polar groups [2]. Imidazoline compounds contain N nuclei and unsaturated double bond of the larger electronegativity and it has a strong adsorption in the steel surface. Because it has good thermal stability, low toxicity and no irritating odor [3,4], it is considered to be excellent corrosion inhibitors in acidic solution.

Abstract: A simple but thermodinamically well-founded method is described for the recalculation of liquidus surfaces and partition coefficients of multicomponent equilibrium phase diagrams used a data file of the liquidus temperature and partition coefficients calculated by CALPHAD method. The applicability of the method is shown in case of Al-Mg-Si ternary alloy systems.