scholarly journals Determination of Temperature-Dependent Coefficients of Viscosity and Surface Tension of Tamarind Seeds (Tamarindus indica L.) Polymer

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 610
Author(s):  
Rishabha Malviya ◽  
Sheetal Jha ◽  
Neeraj Kumar Fuloria ◽  
Vetriselvan Subramaniyan ◽  
Srikumar Chakravarthi ◽  
...  
Keyword(s):  
Activation Energy ◽  
Surface Tension ◽  
Drug Formulation ◽  
Temperature Dependent ◽  
Entropy Of Fusion ◽  
Tamarind Seed ◽  
Future Drug ◽  
Seed Gum ◽  
Calculated Amount

The rheological properties of tamarind seed polymer are characterized for its possible commercialization in the food and pharmaceutical industry. Seed polymer was extracted using water as a solvent and ethyl alcohol as a precipitating agent. The temperature’s effect on the rheological behavior of the polymeric solution was studied. In addition to this, the temperature coefficient, viscosity, surface tension, activation energy, Gibbs free energy, Reynolds number, and entropy of fusion were calculated by using the Arrhenius, Gibbs–Helmholtz, Frenkel–Eyring, and Eotvos equations, respectively. The activation energy of the gum was found to be 20.46 ± 1.06 kJ/mol. Changes in entropy and enthalpy were found to be 23.66 ± 0.97 and −0.10 ± 0.01 kJ/mol, respectively. The calculated amount of entropy of fusion was found to be 0.88 kJ/mol. A considerable decrease in apparent viscosity and surface tension was produced when the temperature was raised. The present study concludes that the tamarind seed polymer solution is less sensitive to temperature change in comparison to Albzia lebbac gum, Ficus glumosa gum and A. marcocarpa gum. This study also concludes that the attainment of the transition state of viscous flow for tamarind seed gum is accompanied by bond breaking. The excellent physicochemical properties of tamarind seed polymers make them promising excipients for future drug formulation and make their application in the food and cosmetics industry possible.

Tris(Trimethylsilyl)Germane (Me3Si)3GeH: A Molecular Model for Sulfur Passivation of Ge(111) Surfaces

2016 ◽  
Vol 255 ◽  
pp. 36-40
Author(s):  
Gilbert Okorn ◽  
Roland Fischer ◽  
Beate Steller ◽  
Philipp Engesser ◽  
Harald Okorn-Schmidt
Keyword(s):  
Activation Energy ◽  
Model Compound ◽  
Elemental Sulfur ◽  
Surface Passivation ◽  
Molecular Model ◽  
Model Reaction ◽  
Temperature Dependent ◽  
Germanium Surface ◽  
Sulfur Passivation

Tristrimethylsilylgermane, (Me3Si)3GeH, was employed as a molecular model compound for hydrogen terminated Ge(111) surfaces. Time and temperature dependent NMR spectroscopy yielded rate constants for the reaction between (Me3Si)3GeH and elemental sulfur and allowed for the determination of the activation energy for this molecular model reaction to mimic germanium surface passivation.

On temperature-dependent frequency factor in thermoluminescence measured with a hyperbolic heating profile

2001 ◽  
Vol 79 (9) ◽  
pp. 1133-1139 ◽  
Author(s):  
W S Singh ◽  
M Bhattacharya ◽  
S D Singh ◽  
P S Mazumdar
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Frequency Factor ◽  
Temperature Dependent ◽  
Order Of Kinetics ◽  
Dependent Frequency ◽  
Symmetry Factor ◽  
Heating Profile

In this paper, we investigate the consequences of the temperature dependence of the frequency factor on thermoluminescence peaks recorded in a hyperbolic heating profile. The temperature dependence of the frequency factor leads to nonuniqueness in the symmetry factor for a particular order of kinetics (b) and causes an error of the order of 5% in the determination of b and an error of the order of 10% in the determination of activation energy (E). PACS No.: 78.60Kn

Automation of selected brazes' dynamic properties in high-temperatures' measurement process

2013 ◽  
Vol 18 (2-3) ◽  
pp. 33-41
Author(s):  
Dominik Sankowski ◽  
Marcin Bakala ◽  
Rafał Wojciechowski
Keyword(s):  
Surface Tension ◽  
High Temperatures ◽  
Dynamic Properties ◽  
Automatic Measurement ◽  
Measurement Methodology ◽  
Joining Process ◽  
Wetting Force ◽  
Research Grant

Abstract The good quality of several manufactured components frequently depends on solidliquid interactions existing during processing. Nowadays, the research in material engineering focuses also on modern, automatic measurement methods of joining process properties, i.a. wetting force and surface tension, which allows for quantitative determination of above mentioned parameters. In the paper, the brazes’ dynamic properties in high-temperatures’ measurement methodology and the stand for automatic determination of braze’s properties, constructed and implmented within the research grant nr KBN N N519 441 839 - An integrated platform for automatic measurement of wettability and surface tension of solders at high temperatures, are widely described

Development of HPLC Method for the Purity Test by Design of Experiments and Determination of Activation Energy of Hydrolytic Degradation Reactions of Sofosbuvir

2020 ◽  
Vol 16 (7) ◽  
pp. 976-987
Author(s):  
Jakub Petřík ◽  
Jakub Heřt ◽  
Pavel Řezanka ◽  
Filip Vymyslický ◽  
Michal Douša
Keyword(s):  
Activation Energy ◽  
Design Of Experiments ◽  
Mobile Phase ◽  
Hydrolytic Degradation ◽  
Isoconversional Method ◽  
Hplc Method ◽  
Organic Modifier ◽  
Calculation Methods ◽  
Degradation Reactions

Background: The present study was focused on the development of HPLC method for purity testing of sofosbuvir by the Design of Experiments and determination of the activation energy of hydrolytic degradation reactions of sofosbuvir using HPLC based on the kinetics of sofosbuvir degradation. Methods: Following four factors for the Design of Experiments were selected, stationary phase, an organic modifier of the mobile phase, column temperature and pH of the mobile phase. These factors were examined in two or three level experimental design using Modde 11.0 (Umetrics) software. The chromatographic parameters like resolution, USP tailing and discrimination factor were calculated and analysed by partial least squares. The chromatography was performed based on Design of Experiments results with the mobile phase containing ammonium phosphate buffer pH 2.5 and methanol as an organic modifier. Separation was achieved using gradient elution on XBridge BEH C8 at 50 °C and a flow rate of 0.8 mL/min. UV detection was performed at 220 nm. The activation energy of hydrolytic degradation reactions of sofosbuvir was evaluated using two different calculation methods. The first method is based on the slope of dependence of natural logarithm of the rate constant on inverted thermodynamic temperature and the second approach is the isoconversional method. Results and Conclusion: Calculated activation energies were 77.9 ± 1.1 kJ/mol for the first method and 79.5 ± 3.2 kJ/mol for the isoconversional method. The results can be considered to be identical, therefore both calculation methods are suitable for the determination of the activation energy of degradation reactions.

Sign in / Sign up

Export Citation Format

Share Document