104 research outputs found
Stigmaphyllon bannisterioides, the correct name for a well‐known neotropical species of Stigmaphyllon (Malpighiaceae)
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149719/1/tax01262.pd
The second law and beyond in microscopic quantum setups
The Clausius inequality (CI) is one of the most versatile forms of the second
law. Although it was originally conceived for macroscopic steam engines, it is
also applicable to quantum single particle machines. Moreover, the CI is the
main connecting thread between classical microscopic thermodynamics and
nanoscopic quantum thermodynamics. In this chapter, we study three different
approaches for obtaining the CI. Each approach shows different aspects of the
CI. The goals of this chapter are: (i) To show the exact assumptions made in
various derivations of the CI. (ii) To elucidate the structure of the second
law and its origin. (iii) To discuss the possibilities each approach offers for
finding additional second-law like inequalities. (iv) To pose challenges
related to the second law in nanoscopic setups. In particular, we introduce and
briefly discuss the notions of exotic heat machines (X machines), and "lazy
demons".Comment: As a chapter of: F. Binder, L. A. Correa, C. Gogolin, J. Anders, and
G. Adesso (eds.), "Thermodynamics in the quantum regime - Recent Progress and
Outlook", (Springer International Publishing). v1 does not include references
to other book chapter
Thermodynamic principles and implementations of quantum machines
The efficiency of cyclic heat engines is limited by the Carnot bound. This
bound follows from the second law of thermodynamics and is attained by engines
that operate between two thermal baths under the reversibility condition
whereby the total entropy does not increase. By contrast, the efficiency of
engines powered by quantum non-thermal baths has been claimed to surpass the
thermodynamic Carnot bound. The key to understanding the performance of such
engines is a proper division of the energy supplied by the bath to the system
into heat and work, depending on the associated change in the system entropy
and ergotropy. Due to their hybrid character, the efficiency bound for quantum
engines powered by a non-thermal bath does not solely follow from the laws of
thermodynamics. Hence, the thermodynamic Carnot bound is inapplicable to such
hybrid engines. Yet, they do not violate the principles of thermodynamics.
An alternative means of boosting machine performance is the concept of
heat-to-work conversion catalysis by quantum non-linear (squeezed) pumping of
the piston mode. This enhancement is due to the increased ability of the
squeezed piston to store ergotropy. Since the catalyzed machine is fueled by
thermal baths, it adheres to the Carnot bound.
We conclude by arguing that it is not quantumness per se that improves the
machine performance, but rather the properties of the baths, the working fluid
and the piston that boost the ergotropy and minimize the wasted heat in both
the input and the output.Comment: As a chapter of: F. Binder, L. A. Correa, C. Gogolin, J. Anders, and
G. Adesso (eds.), "Thermodynamics in the quantum regime - Recent Progress and
Outlook", (Springer International Publishing
Insertion and Substitution Chemistry at the Boron Fourth Position in Charge-Neutral Zwitterionic Tripodal Tris(methimazolyl)borate Ligands
A number of new charge-neutral zwitterionic tris(methimazolyl)borate ligands have been synthesized, either by substitution of the dimethylamine group in the adduct (dimethylamine)tris(methimazolyl)borane (1) or by insertion into its B–N(dimethylamine) bond by an unsaturated Lewis base. Two new anionic ligands, (thiocyanato)tris(methimazolyl)borate and (cyano)tris(methimazolyl)borate, have also been accessed by this method
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