Thermodynamic Perspective Research Articles

Theoretical insights into the radical scavenging performance of common anti-agers from both kinetic and thermodynamic perspectives

In this article, the radical scavenging performance of eight anti-agers (TMQ, ETMQ, DCD, o-MBp24, o-MBp14, p-BBp14, DNPD, and 6PPD) was benchmarked by the experimental residue rates of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, followed by the theoretical investigation from the perspective of both kinetic and thermodynamic factors. Kinetically, anti-agers with lower Gibbs free energy barriers (ΔG≠) presumably exhibit higher scavenging performance. Moreover, the scavenging performance is also controlled by the thermodynamic feature, that is, the small difference in Gibbs free energy between products and reactants (ΔG(R → P)) promotes the scavenging performance. Therefore, the ΔG≠×ΔG(R → P) indicator considering both kinetic and thermodynamic contributions was proposed here to comprehensively explain the difference in the scavenging performance of anti-agers. The strong positive correlation between experimental residues and ΔG≠×ΔG(R → P) values (R2 = 0.806) revealed that the ΔG≠×ΔG(R → P) indicator promises to be a reliable metric to theoretically assess the scavenging performance of anti-agers.

2D Elastic Organic Crystals with Thermomechanical/Acid Responses and Dual‐Mode Optical Waveguides

AbstractAchieving the combination of multiple external stimuli responses and mechanical flexibility has become the current emerging research in the field of crystalline materials. Meanwhile, the modulation of its properties remains challenging. In this work, a 1‐[(E)‐[(6‐methyl‐1,3‐benzothiazol‐2‐yl) imino] methyl] naphthalen‐2‐ol (BNO) crystalline material is reported. The modulation of the mechanical elasticity and thermomechanical responses is achieved by means of polymorphism (form‐I and form‐II). Further, the structural basis of the 2D mechanical properties of form‐I is investigated. Meanwhile, two types of thermomechanical responses appearing in form‐I are explored in detail from the perspective of crystal structure and thermodynamics, and the second thermomechanical response during cooling is successfully predicted. Then, the acid response of the materials is endowed by molecular design, the fluorescence switch is realized through acid and thermal treatments. Finally, the active/passive dual‐mode optical waveguides of the materials are explored.

Thermodynamic work of partial resetting

Partial resetting, whereby a state variable x(t) is reset at random times to a value ax(t) , 0⩽a⩽1 , generalizes conventional resetting by introducing the resetting strength a as a parameter. Partial resetting generates a broad family of non-equilibrium steady states (NESS) that interpolates between the conventional NESS at strong resetting (a = 0) and a Gaussian distribution at weak resetting (a → 1). Here such resetting processes are studied from a thermodynamic perspective, and the mean cost associated with maintaining such NESS are derived. The resetting phase of the dynamics is implemented by a resetting potential Φ(x) that mediates the resets in finite time. By working in an ensemble of trajectories with a fixed number of resets, we study both the steady-state properties of the propagator and its moments. The thermodynamic work needed to sustain the resulting NESS is then investigated. We find that different resetting traps can give rise to rates of work with widely different dependencies on the resetting strength a. Surprisingly, in the case of resets mediated by a harmonic trap with otherwise free diffusive motion, the asymptotic rate of work is insensitive to the value of a. For general anharmonic traps, the asymptotic rate of work can be either increasing or decreasing as a function of the strength a, depending on the degree of anharmonicity. Counter to intuition, the rate of work can therefore in some cases increase as the resetting becomes weaker (a→1) although the work vanishes at a = 1. Work in the presence of a background potential is also considered. Numerical simulations confirm our findings.

A thermodynamic perspective on electrode poisoning in solid oxide fuel cells

A critical challenge to the commercialization of clean and high-efficiency solid oxide fuel cell (SOFC) technology is the insufficient stack lifespan caused by a variety of degradation mechanisms, which are associated with cell components and chemical feedstocks. Cell components related degradation refers to thermal/chemical/electrochemical deterioration of cell materials under operating conditions, whereas the latter regards impurities in feedstocks of oxidant (air) and reductant (fuel). This article provides a thermodynamic perspective on the understanding of the impurities-induced degradation mechanisms in SOFCs. The discussion focuses on using thermodynamic analysis to elucidate poisoning mechanisms in cathodes by impurity species such as Cr, CO2, H2O, and SO2 and in the anode by species such as S (or H2S), SiO2, and P2 (or PH3). The author hopes the presented fundamental insights can provide a theoretical foundation for searching for better technical solutions to address the critical degradation challenges.

Nonequilibrium dynamics and entropy production of a trapped colloidal particle in a complex nonreciprocal medium.

We discuss the two-dimensional motion of a Brownian particle that is confined to a harmonic trap and driven by a shear flow. The surrounding medium induces memory effects modeled by a linear, typically nonreciprocal coupling of the particle coordinates to an auxiliary (hidden) variable. The system's behavior resulting from the microscopic Langevin equationsfor the three variables is analyzed by means of exact moment equationsderived from the Fokker-Planck representation, and numerical Brownian dynamics simulations. Increasing the shear rate beyond a critical value we observe, for suitable coupling scenarios with nonreciprocal elements, a transition from a stationary to a nonstationary state, corresponding to an escape from the trap. We analyze this behavior, analytically and numerically, in terms of the associated moments of the probability distribution, and from the perspective of nonequilibrium thermodynamics. Intriguingly, the entropy production rate remains finite when crossing the stability threshold.

Unveiling polycrystalline silicon channel dissolution mechanism in wet etching process of 3D NAND fabrication

3D NAND is one of the most promising storage devices due to its high storage density and low energy consumption. Selective wet etching of Si3N4 by hot-concentrated phosphoric acid (PA) solution is a key process for 3D NAND fabrication. However, the channel material, polycrystalline silicon (poly-Si), is unexpectedly dissolved due to its inevitable exposure to the PA etching solution, which causes device failure and thus limits the stacking density of 3D NAND. Herein, to avoid the detrimental dissolution of poly-Si, we unveil the mechanism of poly-Si dissolution in PA solution from kinetic and thermodynamic perspectives. We find that the etch process shows a two-stage reaction, in which H2O plays a key role in lowering the activation barrier for poly-Si etching. Further thermodynamic analysis demonstrates that poly-Si prefers to be oxidized by H2O to suboxide rather than to SiO2. Combined with surface chemistry characterization, we propose the dissolution mechanism as a two-stage process involving the dissolution of suboxide interface and bulk poly-Si, where the nucleophilic substitution of Si–H with Si–OH on bulk poly-Si surface determines the overall etch rate. This study advances the 3D NAND development by establishing a theoretical foundation for identifying and implementing efficacious strategies to impede detrimental dissolution.

Remote epitaxy of single-crystal rhombohedral WS2 bilayers

Compared to transition metal dichalcogenide (TMD) monolayers, rhombohedral-stacked (R-stacked) TMD bilayers exhibit remarkable electrical performance, enhanced nonlinear optical response, giant piezo-photovoltaic effect and intrinsic interfacial ferroelectricity. However, from a thermodynamics perspective, the formation energies of R-stacked and hexagonal-stacked (H-stacked) TMD bilayers are nearly identical, leading to mixed stacking of both H- and R-stacked bilayers in epitaxial films. Here, we report the remote epitaxy of centimetre-scale single-crystal R-stacked WS2 bilayer films on sapphire substrates. The bilayer growth is realized by a high flux feeding of the tungsten source at high temperature on substrates. The R-stacked configuration is achieved by the symmetry breaking in a-plane sapphire, where the influence of atomic steps passes through the lower TMD layer and controls the R-stacking of the upper layer. The as-grown R-stacked bilayers show up-to-30-fold enhancements in carrier mobility (34 cm2V−1s−1), nearly doubled circular helicity (61%) and interfacial ferroelectricity, in contrast to monolayer films. Our work reveals a growth mechanism to obtain stacking-controlled bilayer TMD single crystals, and promotes large-scale applications of R-stacked TMD.

Local Entropy Generation Analysis of the Counter-Flow Dew-Point Evaporative Coolers

Abstract A comfortable indoor working circumstance can be accomplished by a ventilation and air conditioning system. There are several factors influencing the quality of indoor air, with the insufficiency of ventilation accounting for over 50% of the overall considerations. While traditional air conditioner is able to fulfill the needs of ventilation and indoor temperature control, low-efficiency and high energy consumption no longer align with the current sustainable and energy-efficiency goals. Thus, the development of energy-saving and high-efficiency air conditioning systems is crucial for realizing green and efficient building practices. Evaporative cooling technology, specifically dew-point evaporative cooling, has garnered extensive attention as an efficient cooling method and a candidate for environmentally friendly and high-performance alternatives to traditional air conditioning systems. This article investigates the thermodynamic losses involved in a dew-point evaporative cooling system using the counter-flow design. Detailed mathematical models for the evaporative cooler along with the entropy generation in the channels are developed. The model facilitates calculations of (1) the entropy generation distribution in different layers within the system and (2) the entropy generation of each layer and the whole system under various input conditions. Approaching the system from the second law of thermodynamics perspective, this model serves as a guide for selecting the optimal operating conditions, thus promoting the widespread application and commercialization of dew-point evaporative cooling systems with the counter-flow structure.

The Impact of Architectural Layout on Urban Heat Island Effect: A Thermodynamic Perspective

The Impact of Architectural Layout on Urban Heat Island Effect: A Thermodynamic Perspective

In-situ tribo-induced formation of superb lubricious carbon-based tribofilms on the catalytical active MoN-Ag film surfaces

The establishment of environmentally friendly lubrication systems is of significant importance to the sustainable development. Here, we demonstrated an environmentally friendly approach, where superb lubricious carbon-based tribofilms formed in situ originating from base oil through tribochemical reactions, on the surfaces of catalytically active MoN-Ag film. We focused on the study of the tribological behavior of the MoN-Ag/oil solid-liquid system under varying loads. Through detailed characterization analysis of the carbon-based tribofilms, we elucidated the mechanism of friction reduction and wear resistance of the MoN-Ag film in the base oil, as well as the formation mechanism of carbon-based tribofilms. Furthermore, we provided a thermodynamic perspective to clarify the influence of load on the tribo-induced tribochemical reactions within the MoN-Ag/oil solid-liquid system.

Revealing the phase transition of steel frames with CFST columns during progressive collapse process from a thermodynamic perspective

Progressive collapse is a standard failure pattern of steel frames, which researchers expect to analyze quantitatively. However, the existing resist progressive collapse analysis methods based on empirical or reliability theories make it challenging to give quantitative results. Based on the stressing state theory, this work attempts to reveal the phase transition loads during the progressive collapse process from a thermodynamic perspective. Firstly, a 1/3-scale 4-bay steel frame with CFST columns is selected as a case study and equated to a thermodynamic/complex system, and its deformation distribution is transformed into state variables. Matrices (Modes) and Hamiltonians (Characteristic parameters) are constructed to describe the steel frame's stressing state in part or overall. The approximate phase transition loads can be detected by applying the clustering analysis criterion. Further, the phase transition loads can be verified from the renormalization perspective by comparing the Test-based and FEM-based phase transition loads. The EPB points can be directly used as a design reference. In summary, this work reveals the stable phase transition loads of steel frames from the thermodynamic perspective for a case study. Also, it enriches the theory and methodology of thermodynamic-based structural failure studies.

Hydrodeoxygenation of biomass-derived fatty acids and esters to biofuels on RuRe/ZSM-5 catalysts: Synergistic effects of ReOx and Brønsted acid sites

The hydrodeoxygenation of fatty acids and esters is a critical pathway to produce biofuels. We report an efficient RuRe/ZSM-5(18) catalyst for hydrodeoxygenation of methyl laurate, the selectivity of n-C12H26 reached up to 95.2 % at complete conversion under the reaction conditions of 200 °C, 3 MPa H2, 3 h. The contribution of ReOx and acid sites was discussed from the perspective of dynamics and thermodynamics. ReOx was available for the adsorption of substrate and intermediates, the acidity from ReOx species and ZSM-5 are conducive to the cleavage of CO bond. The synergistic effects of ReOx and Brønsted acid sites induced Ru0 species to be electron-deficient, which preferred to adsorb aldehyde group in a linear adsorption configuration and facilitated for the hydrogenation of the aldehyde intermediate to alcohol, followed by dehydration to produce hydrocarbons. Thus, RuRe/ZSM-5(18) catalyst presented superior activity and chemoselectivity in the hydrodeoxygenation of methyl laurate as well as a series of fatty acids and esters without loss in carbon numbers in reactant.

Bio-analog dissipative structures and principles of biological behavior

The place of living organisms in the natural world is a nearly perennial question in philosophy and the sciences; how can inanimate matter yield animate beings? A dominant answer for several centuries has been to treat organisms as sophisticated machines, studying them with the mechanistic physics and chemistry that have given rise to technology and complex machines. Since the early 20th century, many scholars have sought instead to naturalize biology through thermodynamics, recognizing the precarious far-from-equilibrium state of organisms. Erwin Bauer was an early progenitor of this perspective with ambitions of “general laws for the movement of living matter”. In addition to taking a thermodynamic perspective, Bauer recognized that organisms are fundamentally behaving systems, and that explaining the physics of life requires explaining the origins of intentionality, adaptability, and self-regulation. Bauer, like some later scholars, seems to advocate for a “new physics”, one that extends beyond mechanics and classical thermodynamic, one that would be inclusive of living systems. In this historical review piece, we explore some of Bauer's ideas and explain how similar concepts have been explored in modern non-equilibrium thermodynamics and dissipative structure theory. Non-living dissipative structures display end-directedness, self-maintenance, and adaptability analogous to organisms. These findings also point to an alternative framework for the life sciences, that treats organisms not as machines but as sophisticated dissipative structures. We evaluate the differences between mechanistic and thermodynamic perspectives on life, and what each theory entails for understanding the behavior of organisms.

A numerical simulation of the hydrothermal characteristics of a microchannel using cavities, ribs, and secondary channels

To tackle the overheating problem in microelectronic devices, microchannel heat sinks (MCHSs) are promising solutions. However, there is a need to improve their thermal performance while maintaining an acceptable pressure drop. This research investigates the effect of integrating multiple passive techniques for heat transfer enhancement, specifically examining the impact of combining triangular cavities, streamlined ribs, and oblique secondary channels (TC-SR-SC) on hydrothermal characteristics across a range of Reynolds numbers 100 to 600. By exploring the influence of each technique and their combining effects on fluid flow and heat transfer, the study aims to strike a balance between high thermal performance and low-pressure drop. Furthermore, the research also explores the thermal resistance, overall performance, entropy generation, and irreversibility of the novel design, comparing it numerically with commensurate geometries using the commercial software, FLUENT. The results reveal that the design of isosceles triangular cavities, streamlined ribs, and secondary channels combination (TC-SR-SC) achieves a maximum overall performance of 1.70 at Re = 400 due to the interruption and redevelopment of the thermal boundary layer. The presence of oblique secondary channels leads to the diversion of mainstream flow, resulting in better flow mixing between main adjacent channels. It also represents the lowest flow and heat transfer irreversibility, ultimately improving thermal performance based on the second law of thermodynamics perspective.

Thermodynamic and kinetic analysis on the biomass syngas fueled chemical looping hydrogen generation process in fixed bed reactor

Because of its simple structure and easy operation, the fixed bed reactor is widely used in the chemical looping process to assess the performance of oxygen carriers (OC) or to evaluate new chemical looping technologies. However, the systematic investigation of the redox behavior and temperature evolution during the chemical looping hydrogen generation (CLHG) process in the fixed bed reactor under different conditions, which is crucial for process optimization and reactor design, has received less attention. In the present work, the redox characteristics of the CLHG process with biomass syngas as the fuel in a fixed bed reactor were investigated and analyzed from a perspective of thermodynamics and kinetics. Results showed that high redox temperature (>800 °C) favors the fuel conversion due to the improved reaction kinetics and favorable thermodynamics. A space velocity in the range of 0.12–0.5 s−1 and superficial velocity of 0.008–0.075 m/s can provide enough reaction time meanwhile enhance the external diffusion of fuel gas, achieving high reduction degree of OC and further high H2 yield (3.4 mmol/g Fe2O3) and high H2 energy efficiency (45 %). Moreover, a violent OC bed temperature rise (100 °C) was observed in the air oxidization stage, which can be mitigated by diluting the Fe2O3 content and decreasing the air flow rate. Finally, the reaction front and flow front moving behavior were discussed in detail for a better understanding of the CLHG process.

Electrochemical separation of tungsten from scrap cemented carbide WC in FLiNaK melt

Molten salt electrolysis is an innovative technology applied to recover tungsten from the scrap of cemented carbide, which enables the realization of energy saving and consumption reduction goals. Currently, numerous studies have focused on the molten salt electrolysis of chlorine salt systems, but still face challenges including low electrolysis efficiency and salt volatilization. Here, we propose to employ the FLiNaK molten salt system for recovering tungsten from the scrap cemented carbide and analyze the feasibility of the dissolution of WC occurring at the anode from the perspective of thermodynamics and electrochemical polarization curves. Moreover, the influence of electrolysis temperature on the dissolution of the anode is also investigated and the productions are identified as nano-flake tungsten powder by characterizing the cathode product using XRD, SEM, EDS, and XPS. A two-step reduction mechanism of W ions was analyzed by electrochemical means such as CV, SWV, etc., and the ionic groups stabilized by W6+ and W4+, and F− in the molten salts were deduced to be WF33+ and WF3+ by DFT simulation calculations. This work provides new guidance for the application of molten salt electrolysis in the recovery of tungsten from scrap cemented carbide.

Construction of porous micro/nano structures on the surface of Ti–Mo–Zr alloys by anodic oxidation for biomedical application

Ti–Mo–Zr alloys have attracted increasing interest for biomedical applications, due to their outstanding properties such as low elastic modulus. To improve the bioactivity of alloys, this study utilized the anodic oxidation method to fabricate porous micro/nano structures on the surface of a series of Ti–Mo–Zr alloys, including the Ti–12Mo-AO, Ti–10Zr-AO, and Ti–12Mo–10Zr-AO groups. The morphology, composition, phase, microhardness, roughness, wettability, adhesion strength, corrosion resistance, bioactivity, and biocompatibility of each group were systematically investigated. The formation mechanism of surfaces was discussed from the perspective of thermodynamics. Our results demonstrated that, Ti–12Mo-AO showed the structure of single-layer regularly arranged nanotubes, while Ti–10Zr-AO and Ti–12Mo–10Zr-AO exhibited a double-layer porous structure with a nano-filamentous upper layer and a densely arranged nanotube lower layer. With low crystallinity, these surfaces showed an amorphous structure and were composed of the oxides of corresponding matrix element. After anodizing, the microhardness and wettability of surfaces increased, while their corrosion resistance decreased. Compared with Ti–12Mo-AO, Ti–10Zr-AO and Ti–12Mo–10Zr-AO possessed a higher degree of roughness, better wettability, stronger interface bonding, and higher apatite forming ability. Furthermore, the biocompatibility of Ti–12Mo–10Zr-AO was superior to that of the other groups. Taken together, our results revealed that, under the same anodic oxidation condition, Ti–Mo–Zr alloys formed different porous micro/nano structures on the surface. Particularly, due to its favorable properties, Ti–12Mo–10Zr-AO is very attractive for future biomedical application.

Visualizing Structure, Growth, and Dynamics of Li Dendrite in Batteries: From Atomic to Device Scales

AbstractThe growth of lithium (Li) dendrites, characterized by construction of internal Li substrate and surface solid electrolyte interphase (SEI), represents a significant hurdle for both liquid‐state and solid‐state Li batteries. To better understand the growth behaviors of these dendrites at atomic to device scale, advanced electron microscopy techniques have emerged as a valuable tool, providing high temporal and spatial resolutions for real‐time observations. In this review, the mechanistic aspects of growth of Li dendrites are delved first from both thermodynamic and kinetic perspectives. Then, a systematic overview of the state‐of‐the‐art in‐situ devices is provided that is developed for integration into electron microscopes, detailing the corresponding static and dynamic structures of Li dendrites. Additionally, the utilization of the non‐destructive cryogenic TEM technique is explored to classify and compare the local fine structure information of as‐formed Li deposits, which are influenced by various factors such as current density, temperature, electrolyte composition, solvents, and additives. Overall, this review article offers a comprehensive understanding of the physical origins associated with Li dendrites, spanning from atomic to device scales and encompassing both liquid and all‐solid‐state battery scenarios, then envisioning fundamental principles and strategies for optimizing batteries and overcoming the critical challenges posed by Li dendrites.

Solid-solution phase formation rules for high entropy alloys: A thermodynamic perspective

To save time and money before starting the production of a high entropy alloy (HEA), it is important to predict the possibility of HEA formation and the probable final microstructure using the solid solution phase formation thermodynamic rules. In this research, a step-by-step calculation of thermodynamic parameters is conducted to predict the possibility of formation and determine the final properties such as ∆Hmix­, ∆Smix, δr, δχ, Ω, VEC, and Tm for three Ni20Co20Cu15Fe20Mn25, Ni35Co20Cu5Fe5Mn35, and Ni5Co5Cu35Fe35Mn20 HEAs. Based on the obtained results, it is not possible to form a HEA with a solid solution structure for the Ni35Co20Cu5Fe5Mn35 and Ni5Co5Cu35Fe35Mn20 systems due to a low ∆Smix value of 11.28 J.mol-1.K-1. Based on the calculated values of ∆Hmix­, intermetallic compound formation and segregation are predicted for Ni35Co20Cu5Fe5Mn35 and Ni5Co5Cu35Fe35Mn20, respectively.

Assessing energy fluxes and carbon use in soil as controlled by microbial activity - A thermodynamic perspective A perspective paper

Soil organic matter (SOM) plays a central role for both the C cycle and soil functions. Plants provide the input and heterotrophic (micro)organisms are essential for the turnover. Microbial metabolism links matter and energy fluxes and generates the highest energy turnover dynamics in SOM because the organisms need both energy and matter for maintenance and growth. In this perspectives paper, we evaluate the knowledge on thermodynamic approaches potentially applicable to study the turnover of organic matter in the soil system. Thermodynamics is essential for understanding organic matter turnover in soil as turnover and storage are controlled by the energy supply to, and consumption by, microbes. Instead of just comparing the heat of combustion of compounds without considering microbial anabolism, we need to apply conventional thermodynamic state variables that can be either estimated using established thermodynamic equations, or measured empirically in soil. In particular, we can follow and quantify overall changes of enthalpies by calorimetry. Here, we suggest to apply a thermodynamic concept with the related experimental approaches of calo(respiro)metry and turnover mass balances including biomass formation. This enables us to better interpret and understand the highly variable carbon use efficiency (CUE) in a multi-substrate system such as soil and to relate this to energy use efficiency (EUE). Combining the experimental measurements of the thermodynamic state variables with mass turnover data allow prediction of whether compounds can be metabolized with energy delivery to microorganisms, or be thermodynamically stabilized under the respective redox and electron acceptor conditions. Energy balancing shows how much energy is actually used and retained in the soil, how much is emitted as heat, and how much may be stabilized due to endergonic turnover reactions. Thermodynamic stabilization should therefore be considered as basic stabilization process for organic compounds in soil.