scholarly journals Synergistic Properties of Arabinogalactan (AG) and Hyaluronic Acid (HA) Sodium Salt Mixtures

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7246
Author(s):  
Antonia Di Mola ◽  
Francesco Ferdinando Summa ◽  
Patrizia Oliva ◽  
Francesco Lelj ◽  
Stefano Remiddi ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Diffusion Coefficients ◽  
Total Concentration ◽  
Molecular Probe ◽  
Corneal Surface ◽  
Unusual Combination ◽  
Salt Mixtures ◽  
Bovine Submaxillary Mucin ◽  
1Hnmr Spectroscopy

The properties of mixtures of two polysaccharides, arabinogalactan (AG) and hyaluronic acid (HA), were investigated in solution by the measurement of diffusion coefficients D of water protons by DOSY (Diffusion Ordered SpectroscopY), by the determination of viscosity and by the investigation of the affinity of a small molecule molecular probe versus AG/HA mixtures in the presence of bovine submaxillary mucin (BSM) by 1HNMR spectroscopy. Enhanced mucoadhesive properties, decreased mobility of water and decreased viscosity were observed at the increase of AG/HA ratio and of total concentration of AG. This unusual combination of properties can lead to more effective and long-lasting hydration of certain tissues (inflamed skin, dry eye corneal surface, etc.) and can be useful in the preparation of new formulations of cosmetics and of drug release systems, with the advantage of reducing the viscosity of the solutions.

Verbesserung des Meß-und Auswerteverfahrens zur Bestimmung der gemeinsamen und partiellen Diffusionskoeffizienten am Beispiel von Kupfer-Gold-Legierungen/An Improved Method for Measuring and Analysing Chemical and Intrinsic Diffusion Coefficients Applied to Copper-Gold Alloys

1975 ◽  
Vol 30 (10) ◽  
pp. 1282-1289 ◽  
Author(s):  
Th. Heumann ◽  
Th. Rottwinkel
Keyword(s):  
Electron Microprobe ◽  
Diffusion Coefficients ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Total Concentration ◽  
Chemical Diffusion ◽  
Diffusion Profile ◽  
Intrinsic Diffusion ◽  
Mean Values

Abstract A method is described which enables the determination of the chemical diffusion coefficients D̃ in a binary system as well as the intrinsic diffusion coefficients of both components with sufficient accuracy. The difference in concentration between the diffusion couples should not exceed 5 at%. Numerous diffusion profiles at different annealing times are taken by electron microprobe analysis from each specimen before calculating D̃ according to a method proposed by Sauer and Freise Combining the results for different pairs of specimens with overlapping concentration range mean values of D̃ are obtained in the total concentration range unter consideration. An analytical expression for D̃ is given, which is used to determine the diffusion profile for a special diffusion couple according to the method of Wagner4 . By this one obtains the total diffusion profile including the flat ends which cannot be accurately determinated by electron microprobe analysis. The determination of the intrinsic diffusion coefficients according to van Loo5 is based on these calculated profiles with additional knowledge of the position of the welding interface. This method has been applied to diffusion measurements in Cu-Au alloys. The following relation for D̃ has been found in the concentration range between 0 and 32 at% Au at 911 °C D̃(N)Cu Au911 °C =3,71·10-10 + 5.04·10-9 N+1.76·10-10 N2 + 1.01 -10-11 N3 [cm2 sec-1 ]. N = mole fraction of Au.

The Calculation of Turbulent Diffusion Coefficients in Aquatic Ecosystems

2019 ◽  
Vol 70 (11) ◽  
pp. 3903-3907
Author(s):  
Galina Marusic ◽  
Valeriu Panaitescu
Keyword(s):  
Transport Equation ◽  
Turbulent Diffusion ◽  
Diffusion Coefficients ◽  
Aquatic Ecosystems ◽  
Specific Area ◽  
Left Bank ◽  
The Right ◽  
Prut River

The paper deals with the issues related to the pollution of aquatic ecosystems. The influence of turbulence on the transport and dispersion of pollutants in the mentioned systems, as well as the calculation of the turbulent diffusion coefficients are studied. A case study on the determination of turbulent diffusion coefficients for some sectors of the Prut River is presented. A new method is proposed for the determination of the turbulent diffusion coefficients in the pollutant transport equation for specific sectors of a river, according to the associated number of P�clet, calculated for each specific area: the left bank, the right bank and the middle of the river.

scholarly journals Migration of mineral oil in elastomers

2021 ◽  
Author(s):  
Tobias Förster ◽  
Artur Blivernitz
Keyword(s):  
Diffusion Coefficients ◽  
Mineral Oil ◽  
Activation Energies ◽  
Concentration Profiles ◽  
Small Reservoir ◽  
Experimental Procedure ◽  
Mineral Oils ◽  
The Absolute ◽  
Suitable Measure

AbstractThis work describes a newly introduced experimental procedure to quantify the diffusion progress of mineral oils locally resolved in NBR. Diffusion of reference oils IRM 901, IRM 902 and IRM 903 in NBR with various acrylonitrile contents was investigated. Classical sorption experiments were performed as a basic characterization and compared to the newly introduced method. Here, elastomer specimens are only being dipped with the bottom in a relatively small reservoir of mineral oil. This provides a determination of locally resolved concentration profiles of mineral oils, and the calculation of diffusion coefficients. These diffusion coefficients follow the same trends like those determined via sorption experiments. Despite differences in the absolute numbers, activation energies of diffusion can be applied as a suitable measure for the compatibility of elastomers and fluids.

scholarly journals Mechanism of tubulin–colchicine recognition: a kinetic study of the binding of the colchicine analogues colchicide and isocolchicine

1997 ◽  
Vol 327 (3) ◽  
pp. 685-688 ◽  
Author(s):  
Chantal DUMORTIER ◽  
Qunying YAN ◽  
Susan BANE ◽  
Yves ENGELBORGHS
Keyword(s):  
Rate Constant ◽  
Total Concentration ◽  
Carbonyl Oxygen ◽  
Protein Fluorescence ◽  
Kinetic And Thermodynamic Parameters ◽  
Methoxy Groups ◽  
Displacement Experiments ◽  
Absorbance Changes ◽  
Initial Binding

Colchicide (IDE) is a colchicine (COL) analogue in which the C-10 methoxy group is replaced by a hydrogen atom. Its binding to tubulin is accompanied by a quenching of the protein fluorescence. The fluorescence decrease shows a monoexponential time dependence. The observed rate constant increases in a non-linear way with the total concentration of IDE, allowing the determination of a binding constant for an initial binding site (K1 = 5300±300 M-1) and the rate constant for the subsequent isomerization (k2 = 0.071±0.002 s-1) at 25 °C. The rate constant, k-2, for the reversed isomerization can be determined by displacement experiments. Despite the minor alteration of the C-ring substituent, the kinetic and thermodynamic parameters of binding are substantially different from those of COL itself, for both steps. In isocolchicine (ISO) the carbonyl oxygen atom and the methoxy groups of the C-ring have been interchanged. Its binding to tubulin only results in small fluorescence and absorbance changes. Therefore competition experiments with MTC [2-methoxy-5-(2ʹ,3ʹ,4ʹ-trimethoxyphenyl)-2,4,6-cycloheptatrien-1-one] were performed. ISO competes rapidly and with low affinity with MTC. Fluorimetric titrations of tubulin with MDL (MDL 27048 or trans-1-(2,5 dimethoxyphenyl)-3-[4-(dimethylamino)phenyl]-2-methyl-2-propen-1-one) in the presence and absence of ISO give evidence for the existence of a second, slow-reacting low-affinity site for ISO that is not accessible to MTC or MDL. The relevance of these results for the recognition of COL is analysed.

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