The second part of this paper develops an approach suggested in
,
(1), 11; which relates ordering in physical systems to symmetrizing. Entropy is frequently interpreted as a quantitative measure of ..."chaos" or "disorder". However, the notions of "chaos" and "disorder" are vague and subjective, to a great extent. This leads to numerous misinterpretations of entropy. We propose that the disorder is viewed as an absence of symmetry and identify "ordering" with symmetrizing of a physical system; in other words, introducing the elements of symmetry into an initially disordered physical system. We explore the initially disordered system of elementary magnets exerted to the external magnetic field H → . Imposing symmetry restrictions diminishes the entropy of the system and decreases its temperature. The general case of the system of elementary magnets demonstrating
-fold symmetry is studied. The T j = T j interrelation takes place, where
and T j are the temperatures of non-symmetrized and
-fold-symmetrized systems of the magnets, correspondingly.
The meaning and evolution of the notion of "temperature" (which is a key concept for the condensed and gaseous matter theories) are addressed from different points of view. The concept of temperature ...has turned out to be much more fundamental than conventionally thought. In particular, the temperature may be introduced for systems built of a "small" number of particles and particles at rest. The Kelvin temperature scale may be introduced into quantum and relativistic physics due to the fact that the efficiency of the quantum and relativistic Carnot cycles coincides with that of the classical one. The relation of temperature with the metrics of the configurational space describing the behavior of systems built from non-interacting particles is demonstrated. The role of temperature in constituting inertia and gravity forces treated as entropy forces is addressed. The Landauer principle asserts that the temperature of a system is the only physical value defining the energy cost of the isothermal erasure of a single bit of information. The fundamental role of the temperature of the cosmic microwave background in modern cosmology is discussed. The range of problems and controversies related to the negative absolute temperature is treated.
Wetting of rough hydrophilic and hydrophobic surfaces is discussed. The stability of the Cassie state, with air trapped in relief details under the droplet, is necessary for the design of true ...superhydrophobic surfaces. The potential barrier separating the Cassie state and the Wenzel state, for which the substrate is completely wetted, is calculated for both hydrophobic and hydrophilic surfaces. When the surface is hydrophobic, the multiscaled roughness of pillars constituting the surface increases the potential barrier separating the Cassie and Wenzel states. When water fills the hydrophilic pore, the energy gain due to the wetting of the pore hydrophilic wall is overcompensated by the energy increase because of the growth of the high-energetic liquid–air interface. The potential barrier separating the Cassie and Wenzel states is calculated for various topographies of surfaces. Structural features of reliefs favoring enhanced hydrophobicity are elucidated.
The informational re-interpretation of the basic laws of the mechanics exploiting the Landauer principle is suggested. When a physical body is in rest or it moves rectilinearly with the constant ...speed, zero information is transferred; thus, the informational affinity of the rest state and the rectilinear motion with a constant speed is established. Inertial forces may be involved in the erasure/recording of information. The analysis of the minimal Szilard thermal engine as seen from the noninertial frame of references is carried out. The Szilard single-particle minimal thermal engine undergoes isobaric expansion relative to accelerated frame of references, enabling the erasure of 1 bit of information. The energy Δ
spent by the inertial force for the erasure of 1 bit of information is estimated as Δ Q ≅ 5 3 k B T ¯ , which is larger than the Landauer bound but qualitatively is close to it. The informational interpretation of the equivalence principle is proposed: the informational content of the inertial and gravitational masses is the same.
Physical roots, exemplifications and consequences of periodic and aperiodic ordering (represented by Fibonacci series) in biological systems are discussed. The physical and biological roots and role ...of symmetry and asymmetry appearing in biological patterns are addressed. A generalization of the Curie–Neumann principle as applied to biological objects is presented, briefly summarized as: “asymmetry is what creates a biological phenomenon”. The “top-down” and “bottom-up” approaches to the explanation of symmetry in organisms are presented and discussed in detail. The “top-down” approach implies that the symmetry of the biological structure follows the symmetry of the media in which this structure is functioning; the “bottom-up” approach, in turn, accepts that the symmetry of biological structures emerges from the symmetry of molecules constituting the structure. A diversity of mathematical measures applicable for quantification of order in biological patterns is introduced. The continuous, Shannon and Voronoi measures of symmetry/ordering and their application to biological objects are addressed. The fine structure of the notion of “order” is discussed. Informational/algorithmic roots of order inherent in the biological systems are considered. Ordered/symmetrical patterns provide an economy of biological information, necessary for the algorithmic description of a biological entity. The application of the Landauer principle bridging physics and theory of information to the biological systems is discussed.
The abrupt change in the apparent contact angle occurring on a rough surface is called wetting transition. This change may be spontaneous or promoted by external stimuli such as pressure or ...vibration. Understanding the physical mechanism of wetting transitions is crucial for the design of highly stable superhydrophobic and omniphobic materials. Wetting regimes occurring on rough surfaces are introduced. Experimental methods of study of wetting transitions are reviewed. Physical mechanisms of wetting transitions on rough surfaces are discussed. Time and energy scaling of wetting transitions are addressed. The problem of the stability of Cassie wetting on inherently hydrophobic and hydrophilic surfaces is discussed. The origin and value of a barrier separating the Cassie and Wenzel wetting states are treated in detail. Hierarchical roughness increases the value of the energy barrier. The stability of Cassie wetting observed on re-entrant topographies is explained. The irreversibility of wetting transitions is explained, based on the asymmetry of the energy barrier, which is low from the side of the metastable (higher-energy) state and high from the side of the stable state. The critical pressure necessary for a wetting transition is introduced. The problem of “dimension” of wetting transition is discussed. Reducing the micro-structural scales enlarges the threshold pressure of a wetting transition. The roles of gravity and air compressibility in wetting transitions are treated. The dynamics of wetting transitions is reviewed. The results of molecular simulations of wetting transitions are presented. The trends of future investigations are envisaged.
Wetting transitions observed under vibration of a 15μl water drop deposited on a micrometrically rough PDMS surface. Display omitted
•Physical mechanisms of wetting transitions on rough surfaces are reviewed.•Experimental methods of study of wetting transitions on rough surfaces are reviewed.•Wetting regimes occurring on rough surfaces are introduced.•The problem of the stability of Cassie wetting is discussed.•The results of molecular simulations of wetting transitions are reviewed.
The goal of this comment note is to express my concerns about the recent paper by Tian Zhao et al. (
,
, 542). It is foreseen that this comment will stimulate a fruitful discussion of the issues ...involved. The principle of the least thermodynamic action is applicable for the analysis of the Carnot cycle using the entropy (not heat) generation extrema theorem. The transversality conditions of the variational problem provide the rectangular shape of the
diagram for the Carnot cycle.
Interfacial crystallization appears as a crucial stage in the numeral natural phenomena and technological applications, such as industry of semi-conductors and manufacturing of nano-whiskers. ...Interfacial aspects of heterogeneous crystallization are surveyed. The review is focused on the interplay of thermodynamic and geometric aspects of the interfacial crystallization. Thermodynamic considerations leading to the Wulff construction are discussed. Equilibrium shape of the crystallized particle in the contact with a foreign substrate giving rise to the Winterbottom construction is treated. The concept of equivalent equilibrium contact angle θeq is introduced. The equivalent contact angle θeq applicable for isotropic crystals does not depend neither on the volume of the crystallized particles nor on the external fields. Bulk contributions to the free energy of the particle such as the bulk heat release in the case of reactive contact or latent heat of crystallization do not influence the equivalent contact angle θeq. Application of the Winterbottom constructions for prediction of the shape of nanoparticles grown on solid substrates is treated. Thermodynamics of interfacial crystallization is discussed. The thermodynamic condition predicting when surface crystallization is thermodynamically favored over homogeneous (bulk) crystallization is supplied. This thermodynamic relation coincides with the condition prescribing the partial wetting of a solid by its melt. Interfacial crystallization in its relation to the “coffee-stain” effect, salt creeping and development of anti-icing surfaces is addressed. Interfacial aspects of epitaxial growth of crystals are considered. The current state-of-art in the field is reviewed.
Display omitted
•Interfacial aspects of heterogeneous crystallization are surveyed.•Thermodynamic considerations leading to the Wulff construction are discussed.•Winterbottom construction predicting the shape of particles grown on solid substrates is treated.•The concept of equivalent equilibrium contact angle is introduced.•Thermodynamics of interfacial crystallization is discussed.•Interfacial aspects of epitaxial growth of crystals are considered.
The notion of three-phase (line) tension remains one of the most disputable notions in surface science. A very broad range of its values has been reported. Experts even do not agree on the sign of ...line tension. The polymer-chain-like model of three-phase (triple) line enables rough estimation of entropic input into the value of line tension, estimated as Γ e n ≅ k B T d m ≅ 10 − 11 N , where d m is the diameter of the liquid molecule. The introduction of the polymer-chain-like model of the triple line is justified by the “water string” model of the liquid state, predicting strong orientation effects for liquid molecules located near hydrophobic moieties. The estimated value of the entropic input into the line tension is close to experimental findings, reported by various groups, and seems to be relevant for the understanding of elastic properties of biological membranes.
Liquid marbles are nonstick droplets wrapped by micro- or nanometrically scaled colloidal particles, representing a platform for a variety of chemical, biological, and microfluidics applications. ...Liquid marbles demonstrate elastic properties and do not coalesce when bounced or pressed. The effective surface tension and Young modulus of liquid marbles are discussed. Physical sources of the elasticity of liquid marbles are considered. Liquids and powders used for the fabrication of liquid marbles are surveyed. This feature article reviews properties and applications of liquid marbles. Liquid marbles demonstrate potential as microreactors, microcontainers for growing micro-organisms and cells, and microfluidics devices. The Marangoni-flow-driven self-propulsion of marbles supported by liquids is addressed.
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