scholarly journals Experimental study on the characteristics of temperature dependent surface/interfacial properties of a non-ionic surfactant aqueous solution at quasi-thermal equilibrium condition

Author(s):  
Dong-Sheng Guo ◽  
Xiao-Bin Li ◽  
Hong-Na Zhang ◽  
Feng-Chen Li ◽  
Ping-Jian Ming ◽  
...  
2020 ◽  
Vol 17 (09) ◽  
pp. 2050134 ◽  
Author(s):  
Zoya Khan ◽  
Shamaila Rani ◽  
Abdul Jawad ◽  
G. Mustafa

In the context of cubic gravity for flat FRW metric we discuss the behavior of cosmological parameters (equation of state (EoS) parameter and square speed of sound) at Hubble horizon with the four different models of Hubble parameter. We observe the validity of generalized second law of thermodynamics (GSLT) and thermal equilibrium condition. It is found that cosmological parameters lie within the observational constraints. Also, GSLT and thermal equilibrium condition holds in almost all cases of Hubble parameter.


2017 ◽  
Vol 21 (6 Part A) ◽  
pp. 2419-2429 ◽  
Author(s):  
Azzedine Abdedou ◽  
Khedidja Bouhadef ◽  
Rachid Bennacer

Laminar forced convection flow through a parallel plates channel completely filled with a saturated porous medium where occurs a uniform heat generation per unit volume with volumetric heat generation is investigated numerically. The Darcy-Brinkman model is used to describe the fluid flow. The energy transport mathematical model is based on the two equations model which assumes that there is no local thermal non-equilibrium between the fluid and the solid phases. The dimensionless governing equations with the appropriate boundary conditions are solved by direct numerical simulation. The effect of the controlling parameters, Biot number, thermal conductivities ratio, heat generation rate, and the Reynolds number on the local thermal equilibrium needed and sufficient condition is analyzed. The results reveal essentially that the local thermal equilibrium condition is unfavorably affected by the increase in the heat generation rate, the thermal conductivities ratio, and the decrease in the Biot number. In addition, for a given heat generation rate, the effect of Reynolds number on the local thermal equilibrium condition is reversed depending on the conductivities ratio threshold.


Author(s):  
Laura Wienands ◽  
Franziska Theiß ◽  
James Eills ◽  
Lorenz Rösler ◽  
Stephan Knecht ◽  
...  

AbstractParahydrogen-induced polarization is a hyperpolarization method for enhancing nuclear magnetic resonance signals by chemical reactions/interactions involving the para spin isomer of hydrogen gas. This method has allowed for biomolecules to be hyperpolarized to such a level that they can be used for real time in vivo metabolic imaging. One particularly promising example is fumarate, which can be rapidly and efficiently hyperpolarized at low cost by hydrogenating an acetylene dicarboxylate precursor molecule using parahydrogen. The reaction is relatively slow compared to the timescale on which the hyperpolarization relaxes back to thermal equilibrium, and an undesirable 2nd hydrogenation step can convert the fumarate into succinate. To date, the hydrogenation chemistry has not been thoroughly investigated, so previous work has been inconsistent in the chosen reaction conditions in the search for ever-higher reaction rate and yield. In this work we investigate the solution preparation protocols and the reaction conditions on the rate and yield of fumarate formation. We report conditions to reproducibly yield over 100 mM fumarate on a short timescale, and discuss aspects of the protocol that hinder the formation of fumarate or lead to irreproducible results. We also provide experimental procedures and recommendations for performing reproducible kinetics experiments in which hydrogen gas is repeatedly bubbled into an aqueous solution, overcoming challenges related to the viscosity and surface tension of the water.


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