Energy Theory Research Articles

Elucidating protein-ligand binding kinetics based on returning probability theory.

The returning probability (RP) theory, a rigorous diffusion-influenced reaction theory, enables us to analyze the binding process systematically in terms of thermodynamics and kinetics using molecular dynamics (MD) simulations. Recently, the theory was extended to atomistically describe binding processes by adopting the host-guest interaction energy as the reaction coordinate. The binding rate constants can be estimated by computing the thermodynamic and kinetic properties of the reactive state existing in the binding processes. Here, we propose a methodology based on the RP theory in conjunction with the energy representation theory of solution, applicable to complex binding phenomena, such as protein-ligand binding. The derived scheme of calculating the equilibrium constant between the reactive and dissociate states, required in the RP theory, can be used for arbitrary types of reactive states. We apply the present method to the bindings of small fragment molecules [4-hydroxy-2-butanone (BUT) and methyl methylthiomethyl sulphoxide (DSS)] to FK506 binding protein (FKBP) in an aqueous solution. Estimated binding rate constants are consistent with those obtained from long-timescale MD simulations. Furthermore, by decomposing the rate constants to the thermodynamic and kinetic contributions, we clarify that the higher thermodynamic stability of the reactive state for DSS causes the faster binding kinetics compared with BUT.

Role of condensate bubbles in enhancing oil droplets and organic acid flotation

Poor adhesion of oil droplet-bubble and the inability to manage dissolved organic matter have hindered flotation efficiency. X-ray photoelectron spectroscopy (XPS) was used for this research to describe the surface chemistry of oil droplets. Multi-component condensate droplet vaporization experiments in produced water (PW). PW at different temperatures was used to investigate droplet vaporization behavior, and the interfacial energy theory and vapor boiling theory were employed to explain the vaporization nucleation mechanism. Contact angle, induction time measurements, and flotation analyses were used to assess the surface chemistry of condensate bubbles and the oil removal effect. The results revealed that when multi-component condensate was vaporized in PW at different temperatures, the light components nucleated inside the condensate droplets and generated bubbles enveloped by the condensate film, and the diameter of the bubbles rose as the temperature increased. X-ray photoelectron spectrometry (XPS) investigation showed the existence of hydrophilic oxygen-containing functional groups on the crude oil's surface. The contact angle between the condensate bubbles and the mask oil surface in PW is >150° and spreads faster, while the contact angle between the methane bubbles, the air bubbles and the oil surface are both <90°. The contact angle and the induction time decrease as the organic acid content of the water increases. Condensate bubble flotation has a greater oil removal efficiency than methane bubble and air bubble, which can achieve the extraction and flotation of emulsified oil droplets (83 %) and dissolved acid (63 %).

Orbital-free QM/MM simulation combined with a theory of solutions.

In a recent study, we developed a kinetic-energy density functional that can be utilized in orbital-free quantum mechanical/molecular mechanical (OF-QM/MM) simulations. The functional includes the nonlocal term constructed from the response function of the reference system of the QM solute. The present work provides a method to combine the OF-QM/MM with a theory of solutions based on the energy representation to compute the solvation free energy of the QM solute in solution. The method is applied to the calculation of the solvation free energy Δμ of a QM water solute in an MM water solvent. It is demonstrated that Δμ is computed as -7.7 kcal/mol, in good agreement with an experimental value of -6.3 kcal/mol. We also develop a theory to map the free energy δμ due to electron density polarization onto the coordinate space of electrons. The free energy density obtained by the free-energy mapping for the QM water clarifies that each hydrogen atom makes a positive contribution (+34.7 kcal/mol) to δμ, and the oxygen atom gives the negative free energy (-71.7 kcal/mol). It is shown that the small polarization free energy -2.4 kcal/mol is generated as a result of the cancellation of these counteracting energies. These analyses are made possible by the OF-QM/MM approach combined with a statistical theory of solutions.

INVESTIGATION OF THE EFFECT OF CLAPS ON THE STRESS-STRAIN STATE OF TANK STRUCTURES

The need to study the problems of reliable operation of the reservoir system is relevant. Special attention should be paid to the specifics of the operation of oil storage tanks and their equipment. The Russian tank farm was formed in the 1970s, a significant part of it has a service life of more than 50 years. The experience of examining such structures with a long service life indicates the presence, in most cases, of the physical aging of their structural elements.&#x0D; The article presents the results of processing a cloud of points created using a ground laser scanner to determine the actual geometric deviations of the reservoir and their combined effect on the reliability of the reservoir.&#x0D; During the survey, a method of work was used that differs from the standard. In the field, a laser scanner was used instead of a theodolite; in office processing, software systems were used that simplify the tasks.&#x0D; In the process of research in the 3DR software package, a triangulation mesh model was created from a cloud of points from a set of finite elements to identify defects located on the wall. The data obtained can be compared with previous and future survey results. Also, the model can be used to create a calculation scheme in PC LIRA 10.&#x0D; We set the actual characteristics of the tank wall to the finite elements (the thickness of the first belt is 12 mm, the next ones 10 mm). The main load combinations were applied to the tank. The calculations were carried out for a combination of loads, including the own weight of the structures, the pressure of the stored product and the overpressure in the gas space. Circular and equivalent stresses according to the 4 (energy) theory of strength were analyzed.&#x0D; The use of a laser scanner and software systems reduces labor costs for tank inspection, improves the quality of work performed, makes it possible to see the real surface of the tank and take into account defects in the aggregate.&#x0D; This method is of practical importance and is currently used by the Department of Inspection of Buildings and Structures.

A novel spring gravity-balance method for spatial articulated manipulators without auxiliary links

Previous studies developed spring-gravity balancing methods for articulated manipulators using auxiliary links. However, these links caused extra inertia and motion interference. To address these issues, a spring balancing method based on the quadratic form was proposed. In this form, matrix components represent the energy change due to the manipulator's posture, i.e., stiffnesses. Gravity balancing can be simplified as the summation of matrices that remain unchanged. However, the matrix component contains the polar angles, which can only describe the links’ direction on a plane, thus making this form applicable only to planar manipulators. To extend its applicability to spatial manipulators, we have reformulated it using local coordinates to describe the manipulator's posture in space. The improved quadratic form can be applied to both planar and spatial manipulators, unifying energy representations of articulated manipulators. By arranging the springs to maintain a constant summation of matrices, energy balance is achieved. The criteria of spring attachment and the rules of using springs are proposed. Simulation of a spatial four-link manipulator show perfect balance can be achieved without auxiliary links using our approach.

A new method for detecting dark Matter and explaining formulas which describe fluid matter

Nowadays there is a new challenge among scientists, all of us know dark energy spreads the universe by constant index, but the big question is whether the universe expanding without stopping. I am not agreeing, because on the other side, we have dark matter and we know the force of dark matter and dark energy are opposite of each other. In this article, it has been tried to explain how to detect dark fluid and made an effort to find a formula that describe the relationship between dark matter and dark energy or totally dark fluid. Throughout the history, many scientists had the idea to estimate the behavior of dark matter by the means of time, it means they desired to see what is the effect of time on the movement of dark fluid and influence of it on expanding and diminishing physical universe. Cosmology, attached to the theory of dark matter and dark energy, elaborates that both of them are in a single framework and they are not separated into ptomaine. In the last section I added time to predict dark fluid treatment by passing time. To pursue this goal, at first an experiment was designed in which by assist of cigarette smoke and electrical light, the behavior of dark fluid was observed by the author. Then, by means of quantum physic equations and adding time as a stable factor to quantum physic equation, a model and formula was coined by which it was possible to show dark fluid movement. It is very significant to state that this final formula was not completely accomplished due to the fact the gravity of black hole was not regarded in this experiment. Asan important factor, by help of cosmic noise, voyager program of NASA, information theory is related to lost galaxy information.

Generalized positive energy representations of groups of jets

Let V be a finite-dimensional real vector space and K a compact simple Lie group with Lie algebra \mathfrak{k} . Consider the Fréchet–Lie group G := J_0^\infty(V; K) of \infty -jets at 0\in V of smooth maps V \to K , with Lie algebra \mathfrak{g}=J_0^\infty(V; \mathfrak{k}) . Let P be a Lie group and write \mathfrak{p}:=\operatorname{Lie}(P) . Let \alpha be a smooth P -action on G . We study smooth projective unitary representations \bar{\rho} of G\rtimes_\alpha P that satisfy a so-called generalized positive energy condition. In particular, this class captures representations that are in a suitable sense compatible with a KMS state on the von Neumann algebra generated by \bar{\rho}(G) . We show that this condition imposes severe restrictions on the derived representation d\bar{\rho} of \mathfrak{g}\rtimes \mathfrak{p} , leading in particular to sufficient conditions for {\bar{\rho}}|_{G} to factor through J_0^2(V; K) , or even through K .

CO2 Capture by Diamines in Dry and Humid Conditions: A Theoretical Approach.

This work is a mechanistic study of the CO2 reaction with diamines under both dry and wet conditions. All protic α,ω-diamines R1H1N1-(CH2)n-N2H2R2, with n = 1-5 and R1 and R2 = H and/or CH3, were investigated. Depending on the nature of the diamine, the reaction was found to follow one of two concerted asynchronous reaction mechanisms with a zwitterion hidden intermediate. Both mechanisms involved two processes. The first process consisted of a nucleophilic attack of the nitrogen N1 of the first amine group on the carbon of CO2, accompanied by the transfer of a hydrogen atom H1 from N1 to the nitrogen N2 of the second amine group, leading to the formation of a carbamate zwitterion. The subsequent process corresponds to the transfer of a hydrogen atom H2 from the second amine group N2 to an oxygen atom of CO2, thus ending the reaction by the formation of carbamic acid. The structure of the zwitterion hidden intermediate was determined using the reactive internal reaction coordinates (RIRC), a reaction pathway visualization tool, consisting of a 3D representation of the potential energy versus the internuclear distances N2-H1 and N2-H2, which correspond to the bond being formed and the bond being broken, respectively. The life span of the transitory species, i.e., the zwitterion, was found to depend on the nature of the second amine group. For primary amines, the life span of the zwitterion was "short", whereas for secondary amines, it was "long". The corresponding mechanisms were termed the "early" and "late" asynchronous mechanism, respectively. Regardless of the mechanism, the activation barriers were found to decrease with the length of the carbon chain linking the two amine groups, with an asymptotic behavior from n = 4. Involvement of a water molecule generates a significant catalytic effect for diamines with short carbon chains (n < 4), whereas for longer chain diamines, water has a slightly adverse effect.

Effect of orientation relationship on the morphology and strengthening effect of chromium precipitation in Cu-0.67Cr-0.3Zr alloy

High strength and high conductivity Cu-0.67Cr-0.3Zr alloy was prepared by vacuum directional solidification equipment. The face centered cubic (FCC) and body centered cubic (BCC) Cr rich precipitations in Cu matrix were characterized by high resolution transmission electron microscopy. In the as cast and solution treated state, a large amount of coherent FCC Cr precipitates is uniformly distributed in the matrix. These FCC Cr precipitates are covered by close packed {111} crystal planes and presents regular morphology. Due to their small size and cube-cube orientation with the matrix, FCC Cr precipitates follows dislocation shearing mechanism, resulting in limited strengthening effect. After aging treatment, both incoherent ordered nearly spherical and incoherent rod-shaped BCC Cr precipitates were formed in the matrix. These incoherent precipitates always follow dislocation bypassing mechanism. Due to its small size and high-volume content, the spherical precipitation plays a major role in improving the strength of the alloy. On the contrary, the influence of rod-shaped precipitates on strength is minimal. According to the minimum free energy theory and local chemical potential equilibrium requirement, the precipitation with Kurdjumov-Sachs (K-S) orientation relationship tends to be rod-shaped extending along the direction of Cu [110] and Cr [111], while the precipitation with Nishiyama-Wassemann (N-W) orientation relationship tends to be nearly spherical.

Mechanical Characteristics of Precast Cracked Concrete under Freeze-Thaw-Load Action

Four types of precast double-cracked concrete specimens and non-cracked control group were prepared, and the specimens were subjected to freezing and thawing cycles and uniaxial compression tests, with a total of five freezing and thawing cycles, namely 0, 25, 50, 75 and 100, in order to analyse the fracture phenomena and mechanical properties of the specimens after freezing and thawing in uniaxial compression, and to determine the damage variables of the precast cracked concrete under the action of freezing and thawing loads on the basis of strain energy and fracture mechanics theories. The test results show that: (1) the crack aggregation mode generated by the compression damage of precast cracked specimens is mainly influenced by the crack inclination angle, when the crack inclination angle is 30°, the specimen undergoes wing tension aggregation, and when the crack inclination angle is 60°/90°, the specimen undergoes a mixed tension-shear aggregation mode; (2) After the freeze-thaw cycle test, the degree of deterioration of the prefabricated cracked specimens is significantly higher than that of the non-cracked specimens, and the loss of compressive strength and Young’s modulus of the specimens with crack inclination angle of 60° and 90° is the most severe, and the decrease of the stress-strain curve is the most obvious; (3) Based on fracture mechanics and damage-strain energy to derive the damage variables of the prefabricated cracked loaded specimens, and based on the Weibull function and the principle of equivalent effect of Lemaitre effect, the damage variables under freeze-thaw loading are also derived based on the Weibull function and Lemaitre equivalent strain principle.

An elastoplastic constitutive model for frozen soil considering fracture of cryostructure and propagation of cracks

The natural frozen soil is formed in long-term geological processes under complex climatic conditions, and the special cryogenic structures are engendered in it. Investigation on the mechanical model of frozen soil with cryostructure can provide reliable measures to control and dispose the deformation of engineering foundations in cold regions. In this research, the crack initiation criterion and propagation path of frozen soil containing ice lens were studied based on available laboratory results. For the frozen soil containing ice lenses, the failure was formed by the propagation and penetration of the wing cracks at tip of ice lens. According to the fracture mechanics and strain energy theory, the structural damage variable of frozen soil was established, the effects of ice lens geometric parameters on the damage variable were analyzed. The elastoplastic tensor of frozen soil with cryostructure was modified using the damage variable which considering fracture of cryostructure and propagation of cracks, and an elastoplastic model was established. The PDE module in COMSOL was adopted to redevelop the proposed model, the rationality of the model was verified and the mechanical properties of natural frozen soil was investigated.

Just sustainabilities: lessons from the Lake Turkana Wind Power project in Kenya

ABSTRACT In the light of increasing socio-ecological crises, there has been a surge in the promotion of renewable energy in the Global South. Previous theories and research often hail these developments as a breakthrough. Yet, just sustainability theorists have pointed to logically plausible problems in these alternatives, suggesting that they do not go far enough and could, indeed, worsen the present crises. Africa’s largest wind power plant, the Lake Turkana Wind Power (LTWP) project in Kenya, provides a useful case study for this purpose. This article focuses on two questions: which are the dominant discourses on the LTWP project and what are the prospects of these discourses to drive just sustainability in Kenya? Drawing on interview data and using critical discourse analysis (CDA) set within a political-economic framework on just sustainabilities this article argues that the project is realised within the dominant capitalist frame, guided by a reliance on market forces, new technologies and a search for new frontiers of capital accumulation, processes that are erected on, and typically drive, local and global inequalities. Thus, the project has not been able to address wider concerns of inclusion in Northern Kenya. Analytically, this evidence shows that mainstream conservative and liberal theories of development and energy are insufficient for analysing the transition from fossil to alternative fuels. This evidence provides further basis to put the case for understanding alternative energy projects, and particularly the LTWP, within a broader framework of alternative, radical theories of just sustainabilities centred on concepts such as just land.

Validation of Actuator Line Modeling and Large Eddy Simulations of Kite-Borne Tidal Stream Turbines against ADCP Observations

The representation of tidal energy in future renewable energy systems is growing. Most of the current tidal turbine designs are limited by the minimum current velocity required for efficient operation. The Deep Green (DG) is a kite-borne tidal power plant designed to sustain efficient operation in tidal current velocities as low as 1.2 ms−1. This could increase the geographical areas suitable for large-scale tidal power arrays. Numerical modeling of the Deep Green was carried out in a previous study using large eddy simulations and the actuator line method. This numerical model is compared with acoustic Doppler current profiler (ADCP) measurements taken in the wake of a DG operating in a tidal flow under similar conditions. To be comparable, and since the ADCP measures current velocities using averages of beam components, the numerical model data were resampled using a virtual ADCP in the domain. The sensitivity of the wake observations to ADCP parameters such as pulse length, bin length, and orientation of the beams is studied using this virtual ADCP. After resampling with this virtual ADCP, the numerical model showed good agreement with the observations. Overall, the LES/ALM model predicted the flow features well compared to the observations, although the turbulence levels were underpredicted for an undisturbed tidal flow and overestimated in the DG wake 70 m downstream. The velocity deficit in the DG wake was weaker in the observations compared to the LES. The ALM/LES modeling of kite-borne tidal stream turbines is suitable for further studies of array optimization and wake propagation, etc.

Theories of disorder and order, energy and information, in sociological thought.

There has always been a close relation between thermodynamic theory and sociological theory, although they repeatedly part company and later rejoin. I discuss some of the most important ways in which the two have been in contact, focusing on the potential passage from theories of energy to theories of information and vice versa. I close by discussing how a closer engagement with classic thermodynamics may continue to be fruitful for sociological theorizing. This article is part of the theme issue 'Thermodynamics 2.0: Bridging the natural and social sciences (Part 2)'.

Investigation of the vibration behavior of nano piezoelectric rod using surface effects and non-local elasticity theory

Due to the importance of the analysis of piezoelectric nanorods and the different conditions they are exposed to in engineering problems, in this research, for the first time, both nonlocal elasticity theory and surface energy theory have been used simultaneously to model a piezoelectric nanorod. The natural frequency values of the system have been extracted using the Galerkin weighted residual method. By applying an external excitation voltage, the forced vibrations of nonlocal nanorods with surface effects are presented. The results are reported for different vibrational modes, and the impact of different parameters such as dimensions, nonlocal parameters, and surface effects are investigated. The results of this study prove that the nonlocal elastic theory is more effective than the surface energy theory on the vibration behavior of piezoelectric nanorods. Also, the effect of piezoelectric properties is strengthened due to the nanoscale of the rods.

Variation and mechanism of asphalt-aggregate interface features under ultraviolet aging based on meso- and micro-observations

Time-dependent variation and mechanism of asphalt-aggregate interface features under ultraviolet (UV) aging have not yet been illustrated. This study explored the time-dependent variation and mechanism of asphalt-aggregate interface features under UV aging. To this end, six asphalt binders were chosen and subjected to different durations of UV aging, and then the variation behaviors of their cohesion-adhesion ability with the changing UV radiation time were analyzed through surface energy theory. Further, the microscopic attributes of asphalt binders experiencing the various UV aging durations were measured and their varying rules were investigated with a series of micro observations. Finally, the relationship between cohesion-adhesion characteristics and microscopic properties were illustrated and thus the variation mechanism of interfacial cohesion and adhesion were revealed by mathematical statistics and image presentation. The results showed that UV aging weakened the cohesion and multi-working adhesion of asphalt binders and the moisture stability of asphalt-aggregate systems, and overall presented a gradually strengthened influence on them with the prolonged UV radiation time, especially the UV radiation exceeded 6 days. The variation of phase morphology of asphalt binders under UV aging depended on the asphalt types and neat asphalt oil sources, and there existed a favorable linear relationship between Catana phase of asphalt binders and surface roughness. Adhesion force, function group and four components (saturate (S), aromatics (Ar), resin (R) and asphaltene (As)) also exhibited a gradually increasing variation as the UV radiation duration went on, and among which, the UV aging reduced the adhesion force of asphalt binders. Adhesion force Fad demonstrated the highest Pearson relevance with the cohesion and aqueous-condition adhesion and the moisture stability of asphalt-aggregate system, and the cohesion-adhesion properties of asphalt binders under UV aging met the multivariate linear mathematical relationship with the microscopic attributes screened, with the goodness-of-fit greater than 0.7000.

Constraints on the parameterized deceleration parameter in FRW universe

Confirmation of accelerated expansion of the Universe probed the concept of dark energy theory, and since then, numerous models have been introduced to explain its origin and nature. The present work is based on reconstructing dark energy by parametrization of the deceleration parameter in the FLRW universe filled with radiation, dark matter and dark energy. We have chosen some well-motivated parametrized models 1-3 in an attempt to investigate the energy density in terms of deceleration parameters by estimating the cosmological parameters with the help of different observational datasets. Also, we have introduced a new model 4 for the parametrization of the deceleration parameter. Then we analyzed the cosmography parameters using the best-fit values of the parameters. Using the information criteria, we have examined the viability of the models.

Resonance simulation of the coupled nonlinear Mathieu’s equation

Numerous theoretical physics and chemistry problems can be modeled using Mathieu’s equations (MEs). They are crucial to the theory of potential energy in quantum systems, which is equivalent to the Schrödinger equation. According to the mentioned applications, thus, the current study investigates the stability behavior of the nonlinear-coupled MEs. The analysis of the coupled harmonic resonance cases imposes two coupled solvability conditions, which leads to coupled parametric nonlinear Landau equations. In addition, a super-harmonic nonlinear resonance combination is presented. Solutions and stability criteria are discussed for each case. It is shown that resonance produces an unstable system. The transition curves are derived. Numerical calculations show the excitation of the frequency on the periodic solutions.

Study on the shear strength and damage constitutive model of the contact surface between PVA fiber-enhanced cement mortar and concrete

In this study, a polyvinyl alcohol (PVA) fiber-enhanced cement mortar (PFCM) with high workability, early strength, and high strength was developed. The influences of water content (w), strength, and surface roughness (Rd) of concrete on the shear strength of its contact surface with PFCM were experimentally investigated, followed by the establishment of damage constitutive model. The PFCM was found to be suitable for spraying and achieved a compressive strength of 102.8 MPa and a flexural strength of 19.6 MPa at 28 days. At 3–7 days, its compressive and flexural strengths reached about 79–80% and 83–90% of the 28-day strength, respectively. The shear load and fracture energy release rate of the PFCM and Concrete contact surfaces is between 6.13 kN and 12.09 kN and 1.13 J/m2 to 2.20 J/m2, respectively, both increasing with the increasing w, strength and Rd of concrete. The increased w of concrete from 0.0% to 5.5% could reduce the porosity and capillary pore content of PFCM by about 43% and 50.4%, respectively, and the increased Rd could enhance the interlocking effect between PFCM and concrete. The damage function proposed based on the Najar energy theory could reflect the evolution characteristics of shearing damage of PFCM and Concrete contact surface, and the damage constitutive model proposed by combining the Weibull statistical distribution function and Guo Zhenhai model could reflect the shear mechanical behavior of the PFCM and Concrete contact surface.

Extend ethylene aromatization single-event kinetic modeling with physical and chemical descriptor based on ZSM-5 catalyst

The ethylene aromatization is critical for the methanol to aromatics and light alkane dehydroaromatization process. The single-event microkinetic (SEMK) model combining the linear free energy theory and solid acid distribution concept were established and extend for the ethylene aromatization process, which can reduce the kinetic parameters and simplify the reaction network by comparison with the SEMK model including subtype elementary steps based on the type of carbenium ions. Further introducing deactivation parameters φ into the model and applying the linear free energy model to the deactivation experimental data, the obtained deactivation parameters φ indicate that the carbon deposition precursors have the greatest impact on reducing the reaction rate of single-molecular reactions and the smallest impact on the hydrogen transfer reaction. Meanwhile, according to the change of reaction enthalpy, effect of carbenium ion structure on methylation, ethylation, cyclization and endo-β scission was investigated by introducing linear free energy concept into the SEMK model. The effect of different acid strengths on elementary steps was investigated based on the acid strength distribution model, it was found that the methylation and oligomerization reactions, the ali-β scission reaction, endo-β scission reaction and the cyclization reaction were more sensitive to strong acidity sites. The physisorption and chemisorption heat are separated from the protonation heat in the linear free energy kinetic model and the acid strength distribution kinetic model, and the absolute values of the obtained physisorption and chemisorption heat increase with the carbon number of carbenium ions. Furthermore, the parameters of the acid strength distribution kinetic model were applied to propane dehydroaromatization on H-ZSM-5 and the ethane dehydroaromatization on Zn/ZSM-5 to confirm the independence of parameters in the SEMK model with the similar reaction network.