The reversible process: A zero‐entropy‐production limit

1996 ◽  
Vol 64 (5) ◽  
pp. 580-583 ◽  
Author(s):  
John S. Thomsen ◽  
Helene C. Bers
Keyword(s):  
Entropy Production ◽  
Reversible Process ◽  
Zero Entropy

Zero-Entropy-Production Melting Temperature of Crystals of Poly(butylene succinate) Formed at High Supercooling of the Melt

2022 ◽  
Author(s):  
Rui Zhang ◽  
Katalee Jariyavidyanont ◽  
Evgeny Zhuravlev ◽  
Christoph Schick ◽  
René Androsch
Keyword(s):  
Entropy Production ◽  
Melting Temperature ◽  
Butylene Succinate ◽  
Zero Entropy

scholarly journals Carnot Efficiency and Zero-Entropy Production Rate Do Not Guarantee Reversibility of a Process

2019 ◽  
Vol 75 (12) ◽  
pp. 948-952 ◽  
Author(s):  
Jae Sung Lee ◽  
Sang Hoon Lee ◽  
Jaegon Um ◽  
Hyunggyu Park
Keyword(s):  
Entropy Production ◽  
Production Rate ◽  
Entropy Production Rate ◽  
Zero Entropy

scholarly journals The Entropy Production of Galaxies

2021 ◽  
Author(s):  
Michael C. Parker ◽  
Chris Jeynes
Keyword(s):  
Black Hole ◽  
Entropy Production ◽  
Spiral Galaxies ◽  
Lagrange Equation ◽  
Supermassive Black Hole ◽  
Virial Mass ◽  
Zero Entropy ◽  
Double Spiral ◽  
The Universe ◽  
Over Time

Double-spiral galaxies are common in the Universe. It is known that the logarithmic double spiral is a Maximum Entropy geometry and represents spiral galaxies well. It is also known that the virial mass of such a galaxy can be approximately determined from the entropy of its central supermassive black hole. But over time the black hole must accrete mass, and therefore the overall galactic entropy must increase. From the associated entropic Euler-Lagrange equation (forming the basis of the Principle of Least Exertion, and also enabling the application of Nöther’s theorem) we show that the galactic entropy production is a conserved quantity, and we derive an appropriate expression for the relativistic entropic Hamiltonian of an idealised spiral galaxy. We generalise Onsager’s celebrated expression for entropy production and demonstrate that galactic entropy production has two parts, one many orders of magnitude larger than the other, and where the smaller is comparable to the Hawking radiation of the central supermassive black hole. We conclude that galaxies cannot be isolated, since even idealised spiral galaxies have non-zero entropy production.

On the Preparation of Bovine α-Thrombin

1978 ◽  
Vol 39 (01) ◽  
pp. 193-200 ◽  
Author(s):  
Erwin F Workman ◽  
Roger L Lundblad
Keyword(s):  
Immobilized Enzyme ◽  
Catalytic Properties ◽  
Specific Activity ◽  
Guanidine Hydrochloride ◽  
Low Molecular Weight ◽  
Reversible Process ◽  
Gel Beads ◽  
Tissue Thromboplastin ◽  
C 50 ◽  
Hydrolysis Of

SummaryAn improved method for the preparation of bovine α-thrombin is described. The procedure involves the activation of partially purified prothrombin with tissue thromboplastin followed by chromatography on Sulfopropyl-Sephadex C-50. The purified enzyme is homogeneous on polyacrylamide discontinuous gel electrophoresis and has a specific activity toward fibrinogen of 2,200–2,700 N.I.H. U/mg. Its stability on storage in liquid media is dependent on both ionic strenght and temperature. Increasing ionic strength and decreasing temperature result in optimal stability. The denaturation of α-thrombin by guanidine hydrochloride was found to be a partially reversible process with the renatured species possessing properties similar to “aged” thrombin. In addition, the catalytic properties of a-thrombin covalently attached to agarose gel beads were also examined. The activity of the immobilized enzyme toward fibrinogen was affected to a much greater extent than was the hydrolysis of low molecular weight, synthetic substrates.

Reversible microscale assembly of nanoparticles driven by the phase transition of a thermotropic liquid crystal

2017 ◽  
Author(s):  
Niamh Mac Fhionnlaoich ◽  
Stephen Schrettl ◽  
Nicholas B. Tito ◽  
Ye Yang ◽  
Malavika Nair ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Self Assembly ◽  
Nematic Phase ◽  
Hierarchical Control ◽  
Building Blocks ◽  
Model System ◽  
Microscopic Level ◽  
Reversible Process ◽  
Thermotropic Liquid Crystal

The arrangement of nanoscale building blocks into patterns with microscale periodicity is challenging to achieve via self-assembly processes. Here, we report on the phase transition-driven collective assembly of gold nanoparticles in a thermotropic liquid crystal. A temperature-induced transition from the isotropic to the nematic phase leads to the assembly of individual nanometre-sized particles into arrays of micrometre-sized aggregates, whose size and characteristic spacing can be tuned by varying the cooling rate. This fully reversible process offers hierarchical control over structural order on the molecular, nanoscopic, and microscopic level and is an interesting model system for the programmable patterning of nanocomposites with access to micrometre-sized periodicities.

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.

Electroanalytical chemistry of vanadium complexes. Comparison of the voltammetric features of amavadine with those of the vanadium complexes with iminodiacetic acid and methyliminodiacetic acid

1989 ◽  
Vol 54 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Roland Meier ◽  
Harald Frank ◽  
Reinhard Kirmse ◽  
Reiner Salzer ◽  
Joachim Stach ◽  
...  
Keyword(s):  
Iminodiacetic Acid ◽  
Vanadium Complexes ◽  
Reduction Mechanism ◽  
Reversible Process ◽  
Electroanalytical Chemistry ◽  
Probable Explanation ◽  
Chemical Sense ◽  
Ece Mechanism ◽  
Methyliminodiacetic Acid

The voltammetric behaviour of amavadine (AV) was found to be considerably different from that of the complexes of VO2+ with methyliminodiacetic acid (MIDA) and iminodiacetic acid (IDA). To get an insight in the rather complicated reduction mechanism of the latter complexes the reductions of V(III) (MIDA) and V(III) (IDA) have been studied for comparison. The species V(III) (MIDA)2 and V(III) (IDA)2 are reduced to the appropriate V(II) complexes in a chemically reversible process. VO(MIDA)2 and VO(IDA)2 are reduced to the same complexes via an ECE mechanism. The investigation of the electroreduction of AV shows that this process is not reversible in the chemical sense. As a probable explanation, the conclusion was drawn that AV and the usual V(IV)O-iminocarboxylato complexes differ in their structures.

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