On a Principle of Maximal Rate of Entropy Production

1987 ◽  
Vol 12 (3) ◽  
Author(s):  
H. Ziegler ◽  
C. Wehrli
Keyword(s):  
Entropy Production ◽  
Maximal Rate

Suppression Criterion of the Phase Growth Based on Extremal Principles of Nonequilibrium Thermodynamics

2008 ◽  
Vol 277 ◽  
pp. 39-46
Author(s):  
Yu.A. Lyashenko
Keyword(s):  
Entropy Production ◽  
Critical Thickness ◽  
Nonequilibrium Thermodynamics ◽  
Model System ◽  
Maximal Rate ◽  
Phase Growth ◽  
Binary Phase ◽  
Thermodynamic Criterion ◽  
Extremal Principles ◽  
Kinetic Criterion

The suppression criterion of the binary phase growth due to addition of a third component is considered. In this case the analysis of the two possible criteria of the first phase growth are considered: first – kinetic criterion based on the balance of components fluxes and second - thermodynamic criterion which is based on the maximal rate of the entropy production principle. We demonstrate that in the case of a model system the thermodynamic criterion lead to a bigger value of the critical thickness of the phases which are suppressed by the growth of the investigated phase.

Platelet Preservation. II. The Response of Human Platelet Suspensions to Hypotonic Stress

1976 ◽  
Vol 36 (01) ◽  
pp. 182-191 ◽  
Author(s):  
J Odink
Keyword(s):  
Human Platelet ◽  
Recovery Process ◽  
Hypotonic Solution ◽  
Maximal Rate ◽  
Platelet Suspension ◽  
Hypotonic Stress ◽  
Initial Decrease ◽  
Platelet Concentration ◽  
Light Absorbance

Summary1. Platelet suspensions were exposed to hypotonic stress. Several parameters of the changes in light absorbance were investigated i. a. the initial decrease in absorbance (Amin), the maximal rate of the recovery process (Vmax), and the value of the absorbance two hours after mixing the platelet suspension with the hypotonic solution.2. The ratio Vmax/Amin appeared to be independent of both platelet concentration and, within a specific range, decrease in osmolarity.3. Cryoprotectants appeared to disturb the response to hypotonic stress.4. Cryopreservation caused a decrease in the light absorbance of the platelet suspension, of Amin, and of the recovery process.

Functional Fractionation of Platelets: Aggregation Kinetics and Glycoprotein Labeling of Differing Platelet Populations

1982 ◽  
Vol 48 (02) ◽  
pp. 211-216 ◽  
Author(s):  
V M Haver ◽  
A R L Gear
Keyword(s):  
Galactose Oxidase ◽  
Aggregation Kinetics ◽  
Maximal Rate ◽  
Membrane Glycoproteins ◽  
Whole Cells ◽  
Reversible Aggregation ◽  
Significant Difference ◽  
Small Doses ◽  
Major Loss ◽  
Kinetics Of

SummaryPlatelet heterogeneity has been studied with a technique called functional fractionation which employs gentle centrifugation to yield subpopulations (“reactive” and “less-reactive” platelets) after exposure to small doses of aggregating agent. Aggregation kinetics of the different platelet populations were investigated by quenched-flow aggregometry. The large, “reactive” platelets were more sensitive to ADP (Ka = 1.74 μM) than the smaller “less-reactive” platelets (Ka = 4.08 μM). However, their maximal rate of aggregation (Vmax, % of platelets aggregating per sec) of 23.3 was significantly lower than the “less-reactive” platelets (Vmax = 34.7). The “reactive” platelets had a 2.2 fold higher level of cyclic AMP.Platelet glycoproteins were labeled using the neuraminidase-galactose oxidase – [H3]-NaBH4 technique. When platelets were labeled after reversible aggregation, the “reactive” platelets showed a two-fold decrease in labeling efficiency (versus control platelets). However, examination of whole cells or membrane preparations from reversibly aggregated platelets revealed no significant difference in Coomassie or PAS (Schiff) staining.These results suggest that the large, “reactive” platelets are more sensitive to ADP but are not hyperaggregable in a kinetic sense. Reversible aggregation may cause a re-orientation of membrane glycoproteins that is apparently not characterized by a major loss of glycoprotein material.

Complete monotonicity of entropy production in chemical reaction

1981 ◽  
Vol 46 (2) ◽  
pp. 452-456
Author(s):  
Milan Šolc
Keyword(s):  
Entropy Production ◽  
Equilibrium Constant ◽  
Chemical Reaction ◽  
Relative Entropy ◽  
Order Reaction ◽  
Complete Monotonicity ◽  
First Order Reaction ◽  
First Order ◽  
Completely Monotonic ◽  
Derivatives Of

The successive time derivatives of relative entropy and entropy production for a system with a reversible first-order reaction alternate in sign. It is proved that the relative entropy for reactions with an equilibrium constant smaller than or equal to one is completely monotonic in the whole definition interval, and for reactions with an equilibrium constant larger than one this function is completely monotonic at the beginning of the reaction and near to equilibrium.

Optimal hydraulic design of an ultra-low specific speed centrifugal pump based on the local entropy production theory

2019 ◽  
Vol 233 (6) ◽  
pp. 715-726 ◽  
Author(s):  
Hucan Hou ◽  
Yongxue Zhang ◽  
Xin Zhou ◽  
Zhitao Zuo ◽  
Haisheng Chen
Keyword(s):  
Entropy Production ◽  
Centrifugal Pump ◽  
Orthogonal Design ◽  
High Energy ◽  
Geometrical Parameters ◽  
Production Theory ◽  
Local Entropy ◽  
Hydraulic Design ◽  
Low Specific Speed ◽  
Specific Speed

The ultra-low specific speed centrifugal pump has been widely applied in aerospace engineering, metallurgy, and other industrial fields. However, its hydraulic design lacks specialized theory and method. Moreover, the impeller and volute are designed separately without considering their coupling effect. Therefore, the optimal design is proposed in this study based on the local entropy production theory. Four geometrical parameters are selected to establish orthogonal design schemes including blade outlet setting angle, wrapping angle volute inlet width, and throat area. Subsequently, a 3D steady flow with Reynolds stress turbulent model and energy equation model is numerically conducted and the entropy production is calculated by a user-defined function code. The range analysis is made to identify the optimal scheme indicating that the combination of local entropy production and orthogonal design is feasible on pump optimization. The optimal pump is visibly improved with an increase of 1.08% in efficiency. Entropy production is decreased by 16.75% and 6.03% in impeller and volute, respectively. High energy loss areas are captured and explained in terms of helical vortex and wall friction, and the turbulent and wall entropy production are respectively reduced by 3.82% and 14.34% for the total pump.

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