A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perov...A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perovskite solar cells(C-PSCs),which have a large interface energy level mismatch.The regulation of perovslite's surface energetics is an effective way to improve the V_(bi)and promote charge extraction,which is typically achieved by organic molecules.However,the insulating nature of organic molecules also negatively hinders charge transfer,resulting in a contradiction of"extraction-transport".Quantum dots(Q.Ds)have great potential for energetics regulation of perovskite film due to their semiconductor properties and inherent large dipole moments,but have not yet been explored.In this work,we propose a strategy of discrete embedding semiconductor QDs at the surface grain boundaries of the perovskite film to regulate surface energetics.The QDs change the energetics of the perovskite film surface,transforming the surface energetics from n-to p-type,thus constructing p-n homojunction at the interface.This significantly enhances the Vbi at the perovskite/carbon electrode interface,promoting hole extraction.In addition,the embedded discrete distribution of QDs at the upper surface grain boundaries ensures efficient transport of the extracted holes to the carbon electrode,overcoming the contradiction of"extraction-transport"for traditional energetics control strategies.Consequently,the fabricated planar HTL-free C-PSCs achieve an efficiency of 20.10%(certified 19.8%),which is one of the highest values reported for this kind of device.展开更多
Ocean mixing is a consequence of essential dynamic processes such as internal tides and lee waves that occur near the seafloor topography.Internal tides and lee waves are generated by barotropic tidal currents and geo...Ocean mixing is a consequence of essential dynamic processes such as internal tides and lee waves that occur near the seafloor topography.Internal tides and lee waves are generated by barotropic tidal currents and geostrophic flows,respectively.Ocean current is composed of multiple flows;thus,internal tides and lee waves occur concurrently in the real ocean.In this paper,the Massachusetts Institute of Technology general circulation model(MITgcm)is used to conduct 2D numerical experiments.By varying background flow intensities,the energy and dissipation relationship between internal tides and lee waves are investigated.The results reveal that the internal tide beams become asymmetric due to the influence of Doppler shift.The lee wave structure gradually leads the wave field when the background flow velocity rises constantly.The presence of a background flow increases the energy portion of the high-mode wave by up to 15%-20%.Moreover,strong shear,owing to the background flow,considerably increases dissipation.When the background flow velocity is higher than the barotropic tidal current velocity,the isopycnal overturn triggered by the lee wave generates a dissipation of the same order of magnitude as the shear.展开更多
Gravitational potential energy （GPE） source and sink due to stirring and cabbeling associated with sigma dif fusion/ advection is analyzed. It is shown that GPE source and sink is too big, and they are not closely l...Gravitational potential energy （GPE） source and sink due to stirring and cabbeling associated with sigma dif fusion/ advection is analyzed. It is shown that GPE source and sink is too big, and they are not closely linked to physical property distribution, such as temperature, salinity and velocity. Although the most frequently quoted advantage of sigma coordinate models are their capability of dealing with topography; the exces sive amount of GPE source and sink due to stirring and cabbeling associated with sigma diffusion/advec tion diagnosed from our analysis raises a very serious question whether the way lateral diffusion/advection simulated in the sigma coordinates model is physically acceptable. GPE source and sink in three coordinates is dramatically different in their magnitude and patterns. Overall, in terms of simulating lateral eddy diffu sion and advection isopycnal coordinates is the best choice and sigma coordinates is the worst. The physical reason of the excessive GPE source and sink in sigma coordinates is further explored in details. However, even in the isopycnal coordinates, simulation based on the Eulerian coordinates can be contaminated by the numerical errors associated with the advection terms.展开更多
Gravitational Potential Energy （GPE） change due to horizontal/isopycnal eddy diffusion and advection is examined. Horizontal/isopycnal eddy diffusion is conceptually separated into two steps： stirring and sub scale...Gravitational Potential Energy （GPE） change due to horizontal/isopycnal eddy diffusion and advection is examined. Horizontal/isopycnal eddy diffusion is conceptually separated into two steps： stirring and sub scale diffusion. GPE changes associated with these two steps are analyzed. In addition, GPE changes due to stirring and subscale diffusion associated with horizontal/isopycnal advection in the Eulerian coordinates are analyzed. These formulae are applied to the SODA data for the world oceans. Our analysis indicates that horizontal/isopycnal advection in Eulerian coordinates can introduce large artificial diffusion in the model. It is shown that GPE source/sink in isopycnal coordinates is closely linked to physical property distribution, such as temperature, salinity and velocity. In comparison with z-coordinates, GPE source/sink due to stir ring/cabbeling associated with isopycnal diffusion/advection is much smaller. Although isopycnal coordi nates may be a better choice in terms of handling lateral diffusion, advection terms in the traditional Eule rian coordinates can produce artificial source of GPE due to cabbeling associated with advection. Reducing such numerical errors remains a grand challenge.展开更多
Initially thought to be an opioid receptor subtype, Sigma-1 receptors (S1R) are now known to be unique proteins that have chaperone-like properties. As such, they play critical roles in cellular signaling, homeostasis...Initially thought to be an opioid receptor subtype, Sigma-1 receptors (S1R) are now known to be unique proteins that have chaperone-like properties. As such, they play critical roles in cellular signaling, homeostasis, and cell survival. These roles offer significant insight for understanding homeostasis of normal physiologic processes, and the pathophysiologic consequences of disruption of normal function. Because of the broad nature of chaperone action, S1R agonists and antagonists represent potential drug discovery goals for the pharmacotherapeutic treatment of a variety of disorders that result from dysfunctional proteins. The present study summarizes the S1R as a pharmacologic chaperone crucial for protein folding and cellular homeostasis. Through literature review and thermodynamic analysis, it explores how S1R stabilizes target proteins, influencing neuroprotection and potential drug therapies. The binding of chaperones to target proteins is thermodynamically favorable, offering insights into treating diseases linked to protein misfolding.展开更多
The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved ...The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved heat is helpful in terms of understanding the nature of the interactions be- tween the catalyst and the adsorbed species, and provides insights into the reactivity of the catalyst. Although various techniques have previously been applied to assessments of evolved heat, direct measurements using a Tian-Calvet microcalorimeter are currently the most reliable method for this purpose. In this review, we summarize the relationship between the adsorption/reaction energetics determined by microcalorimetry and the reactivities of supported catalysts, and examine the im- portant role of microcalorimetry in understanding catalytic performance from the energetic point of view.展开更多
Two important nonlinear properties of seawater thermodynamics linked to changes of water density, cab beling and elasticity （compressibility）, are discussed. Eddy diffusion and advection lead to changes in den sity;...Two important nonlinear properties of seawater thermodynamics linked to changes of water density, cab beling and elasticity （compressibility）, are discussed. Eddy diffusion and advection lead to changes in den sity; as a result, gravitational potential energy of the system is changed. Therefore, cabbeling and elasticity play key roles in the energetics of lateral eddy diffusion and advection. Vertical eddy diffusion is one of the key elements in the mechanical energy balance of the global oceans. Vertical eddy diffusion can be con ceptually separated into two steps： stirring and subscale diffusion. Vertical eddy stirring pushes cold/dense water upward and warm/light water downward; thus, gravitational potential energy is increased. During the second steps, water masses from different places mix through subscale diffusion, and water density is increased due to cabbeling. UsingWOA01 climatology and assuming the vertical eddy diffusivity is equal to a constant value of 2x103 pa2/s, the total amount of gravitational potential energy increase due to vertical stirring in the world oceans is estimated at 263 GW. Cabbeling associated with vertical subscale diffusion is a sink of gravitational potential energy, and the total value of energy lost is estimated at 73 GW. Therefore, the net source of gravitational potential energy due to vertical eddy diffusion for the world oceans is estimated at 189 GW.展开更多
An evolving material structure is in a non-equilibrium state, with free energy expressed by the generalized coordinates. A global approach leads to robust computations for the generalized thermodynamic forces. Those f...An evolving material structure is in a non-equilibrium state, with free energy expressed by the generalized coordinates. A global approach leads to robust computations for the generalized thermodynamic forces. Those forces drive various kinetic processes, causing dissipation at spots, along curves, surfaces and interfaces, and within volumetric regions. The actual evolution path, and therefore the final equilibrium state, is determined by the energetics and kinetics. A virtual work principle Links the free energy landscape and the kinetic processes, and assigns a viscous environment to every point on the landscape. The approach leads to a dynamical system that governs the evolution of generalized coordinates. The microstructural evolution is globally characterized by a basin map in the coordinate space; and by a diversity map and a variety map in the parameter space. The control of basin boundaries raises the issue of energetic and kinetic bifurcations. The variation of basin boundaries under different sets of controlling parameters provides an analytical way to plot the diversity maps of structural evolution.展开更多
Study of oceanic circulation and climate requires models which can simulate tracer eddy diffusion and ad vection accurately. It is shown that the traditional Eulerian coordinates can introduce large artificial hori zo...Study of oceanic circulation and climate requires models which can simulate tracer eddy diffusion and ad vection accurately. It is shown that the traditional Eulerian coordinates can introduce large artificial hori zontal diffusivity/viscosity due to the incorrect alignment of the axis. Therefore, such models can smear sharp fronts and introduce other numerical artifacts. For simulation with relatively low resolution, large lateral diffusion was explicitly used in models; therefore, such numerical diffusion may not be a problem. However, with the increase of horizontal resolution, the artificial diffusivity/viscosity associated with hori zontal advection in the commonly used Eulerian coordinates may become one of the most challenging ob stacles for modeling the ocean circulation accurately. Isopycnal eddy diffusion （mixing） has been widely used in numerical models. The common wisdom is that mixing along isopycnal is energy free. However, a careful examination reveals that this is not the case. In fact, eddy diffusion can be conceptually separated into two steps： stirring and subscale diffusion. Due to the thermobaric effect, stirring, or exchanging water masses, along isopycnal surface is associated with the change of GPE in the mean state. This is a new type of instability, called the thermobaric instability. In addition, due to cabbeling subscale diffusion of water parcels always leads to the release of GPE. The release of GPE due to isopycnal stirring and subscale diffusion may lead to the thermobaric instability.展开更多
Nonlinear three-dimensional vibration of axially moving strings is investigated in the view of energetics. The governing equation is derived from the Eulerian equation of motion of a continuum for axially accelerating...Nonlinear three-dimensional vibration of axially moving strings is investigated in the view of energetics. The governing equation is derived from the Eulerian equation of motion of a continuum for axially accelerating strings. The time-rate of the total mechanical energy associated with the vibration is calculated for the string with its ends moving in a prescribed way. For a string moving in a constant axial speed and constrained by two fixed ends, a conserved quantity is proved to remain unchanged during three-dimensional vibration, while the string energy is not conserved. An approximate conserved quantity is derived from the conserved quantity in the neighborhood of the straight equilibrium configuration. The approximate conserved quantity is applied to verify the Lyapunov stability of the straight equilibrium configuration. Numerical simulations are performed for a rubber string and a steel string. The results demonstrate the variation of the total mechanical energy and the invariance of the conserved quantity.展开更多
A 72-h high-resolution simulation of Supertyphoon Rammasun （2014） is performed using the Advanced Research Weather Research and Forecasting model. The model covers an initial 18-h spin-up, the 36-h rapid intensifica...A 72-h high-resolution simulation of Supertyphoon Rammasun （2014） is performed using the Advanced Research Weather Research and Forecasting model. The model covers an initial 18-h spin-up, the 36-h rapid intensification （RI） period in the northern South China Sea, and the 18-h period of weakening after landfall. The results show that the model reproduces the track, intensity, structure of the storm, and environmental circulations reasonably well. Analysis of the surface energetics under the storm indicates that the storm＇s intensification is closely related to the net energy gain rate （eg）, defined as the difference between the energy production （PD） due to surface entropy flux and the energy dissipation （Ds） due to surface friction near the radius of maximum wind （RMW）. Before and during the RI stage, the ~：g is high, indicating sufficient energy supply for the storm to intensify. However, the Sg decreases rapidly as the storm quickly intensifies, because the Ds increases more rapidly than the PD near the RMW. By the time the storm reaches its peak intensity, the Ds is about 20% larger than the PD near the RMW, leading to a local energetics deficit under the eyewall. During the mature stage, the PD and Ds can reach a balance within a radius of 86 km from the storm center （about 2.3 times the RMW）. This implies that the local PD under the eyewall is not large enough to balance the Ds, and the radially inward energy transport from outside the eyewall must play an important role in maintaining the storm＇s intensity, as well as its intensification.展开更多
A fully nonlinear,three-dimensional nonhydrostatic model driven by four principal tidal constituents(M2,S2,K1,and O1) is used to investigate the spatial-temporal characteristics and energetics of internal tides in Luz...A fully nonlinear,three-dimensional nonhydrostatic model driven by four principal tidal constituents(M2,S2,K1,and O1) is used to investigate the spatial-temporal characteristics and energetics of internal tides in Luzon Strait(LS).The model results show that,during spring(neap) tides,about 64(47) GW(1 GW=109 W) of barotropic tidal energy is consumed in LS,of which 59.0%(50.5%) is converted to baroclinic tides.About 22(11) GW of the derived baroclinic energy flux subsequently passes from LS,among which 50.9%(54.3%) flows westward into the South China Sea(SCS) and 45.0%(39.7%) eastward into the Pacific Ocean,and the remaining 16(13) GW is lost locally owing to dissipation and convection.It is revealed that generation areas of internal tides vary with the spring and neap tide,indicating different source areas for internal solitary waves in the northern SCS.The region around the Batan Islands is the most important generation region of internal tides during both spring and neap tides.In addition,the baroclinic tidal energy has pronounced seasonal variability.Both the total energy transferred from barotropic tides to baroclinic tides and the baroclinic energy flux flowing out of LS are the highest in summer and lowest in winter.展开更多
The basic energy balance model is applied to analyze the hohlraum energetics data from the Shenguang(SG)series laser facilities and the National Ignition Facility(NIF)experiments published in the past few years.The an...The basic energy balance model is applied to analyze the hohlraum energetics data from the Shenguang(SG)series laser facilities and the National Ignition Facility(NIF)experiments published in the past few years.The analysis shows that the overall hohlraum energetics data are in agreement with the energy balance model within 20%deviation.The 20%deviation might be caused by the diversity in hohlraum parameters,such as material,laser pulse,gas filling density,etc.In addition,the NIF's ignition target designs and our ignition target designs given by simulations are also in accordance with the energy balance model.This work confirms the value of the energy balance model for ignition target design and experimental data assessment,and demonstrates that the NIF energy is enough to achieve ignition if a 1D spherical radiation drive could be created,meanwhile both the laser plasma instabilities and hydrodynamic instabilities could be suppressed.展开更多
Measurements were made on the contents of protein, lipid, glycogen (PLG) and water, and on caloric values and amino acids, in muscle of three mudskippers Periophthalmis cantonensis, Scarteiaos viridis and Boleophthalm...Measurements were made on the contents of protein, lipid, glycogen (PLG) and water, and on caloric values and amino acids, in muscle of three mudskippers Periophthalmis cantonensis, Scarteiaos viridis and Boleophthalmus pectinirostris collected from Haicang, Xiamen. The essential amino acids (EAA) for these fishes were also studied with radioisotopic trace method. The results showed: (1) The content of each component in tested fish muscles differed slightly, and protein was the most important component making up from 6.685% to 9.891% of the wet weight (about 44.21%-50.45% of dry weight); (2) Energy calculated from the sum of protein, lipid and glycogen in wet muscle was low (<4.3kJ/g) in these fishes, especially in B. pectinirostris (<3.1 kJ/g); the ratios of energy to protein content (E/P) also were low (<39.873 -45.535kJ/g); (3) Seventeen amino acids were determined in these three fishes. The content of the same amino acid (among the seventeen) tested in different species and sexes varied slightly. The amounts of methionine, phenylalanine lysine, arginme, histidine, threonine isoleucine and leucine which are indispensable for the needs of human beings and animals were relative-ly high, accounting for 47.35%-48.06% of the total amino acid content. (4) Leucine, isoleucine, arginme, lysine, phenylalanine, tryptophan, methionine, histidine, threonine, and valine, are essential in the diet of the three mudskippers as the radioisotopic trace method using D-[U-^(14) C]-glucose showed little or no radioactivity was incorporated into these ten amino acids.展开更多
The stability of small vacancy clusters including divacancy,trivacancy and tetravacancy has been studied in body-centered cubic high-entropy alloy Nb_(0.75)ZrTiV_(0.5) in structures of random solid solution and short-...The stability of small vacancy clusters including divacancy,trivacancy and tetravacancy has been studied in body-centered cubic high-entropy alloy Nb_(0.75)ZrTiV_(0.5) in structures of random solid solution and short-range order by first-principles calculations and molecular dynamics simulations.Different from conventional body-centered cubic metals,the tightly bound configurations have a lower structural stability and are not preferred energetically in the studied high-entropy alloy.Instability of vacancy configurations leads to vacancy-atom exchanges that favor less compact configurations.The formation energy of small vacancy clusters is much smaller than its constituent elements of Nb and V due to the large structural adjustment induced by severe local lattice distortion.The difference in local lattice distortion and elemental arrangement in the vacancy neighborhood leads to significant site-to-site variation in vacancy cluster energy and configuration.The formation energy has a strong correlation with the local energy state of the vacancy configuration and the extent of structural relaxation.Compared to random solid solution,the structure of short-range order has a higher stability for the most compact cluster configurations and tends to have higher vacancy cluster formation energy.According to classical molecular dynamics simulations of cluster diffusion at high temperature,the studied high-entropy alloy has a higher probability of cluster dissociation compared to Nb and V.The unconventional energetics of small vacancy clusters is expected to have a profound impact on their generation,diffusion,dissociation,coalescence,as well as the defect microstructure evolution during irradiation.展开更多
In development of baroclinic disturbances, baroclinity of basic temperature field varies with conversion of available potential energy. The growth rate which depends on the baroclinity varies as well. However, in prev...In development of baroclinic disturbances, baroclinity of basic temperature field varies with conversion of available potential energy. The growth rate which depends on the baroclinity varies as well. However, in previous linear theories, the growth rate was considered constant, so development of disturbances was not constrained by energy sources in the linear theories. In terms of energy conservation and conversion in an isolated atmosphere, we may study the variations in the baroclinity and growth rate and draw the corresponding pictures of perturbation developments in the varying environments. The amplification for the most unstable Eady wave is discussed as an example. It will be found that growth of baroclinic perturbations constrained by energy conservation is significantly different from the growth at the initial constant rate after mature stage.展开更多
The structures,energetics,and infrared(IR)spectra of the cationic monomethylamine-water clusters,[(CH3NH2)(H2O)n]^+(n=1-5),have been studied using quantum chemical calculations at the MP2/6-311+G(2d,p)level.The result...The structures,energetics,and infrared(IR)spectra of the cationic monomethylamine-water clusters,[(CH3NH2)(H2O)n]^+(n=1-5),have been studied using quantum chemical calculations at the MP2/6-311+G(2d,p)level.The results reveal that the formation of protontransferred CH2NH3+ ion core structure is preferred via the intramolecular proton transfer from the methyl group to the nitrogen atom and the water molecules act as the acceptor for the O…HN hydrogen bonds with the positively charged NH3^+ moiety of CH2NH3^+,whose motif is retained in the larger clusters.The CH3NH2^+ ion core structure is predicted to be less energetically favorable.Vibrational frequencies of CH stretches,hydrogen-bonded and free NH stretches,and hydrogen-bonded OH stretches in the calculated IR spectra of the CH2NH3^+ and CH3NH2^+ type structures are di erent from each other,which would a ord the sensitive probes for fundamental understanding of hydrogen bonding networks generated from the radiation-induced chemical processes in the[(CH3NH2)(H2O)n]+complexes.展开更多
Mitochondria and neuronal activity:The brain is one of the highest energy demanding organs,consuming~20%of the total ATP produced by the whole body.Importantly,neurons mainly rely on ATP synthesized by mitochondrial b...Mitochondria and neuronal activity:The brain is one of the highest energy demanding organs,consuming~20%of the total ATP produced by the whole body.Importantly,neurons mainly rely on ATP synthesized by mitochondrial bioenergetics and neuronal activity is strictly dependent on specific mitochondrial localization at synapses,sites consuming a high amount of energy requested for both pre-and post-synaptic processes.Here,mitochondria produce ATP and buffer Ca^2+rises,two essential processes for neurotransmission and generation of membrane potential along the axon(Magistretti and Allaman,2015).展开更多
he characteristic study,by means of in-situ IR spectroscopy, of chemisorbed species on the Ni-catalysts for the partial oxidation of methane(POM)to syngas demonstrated the existence of CH_x(a)and H_xCO(a)adspecies on...he characteristic study,by means of in-situ IR spectroscopy, of chemisorbed species on the Ni-catalysts for the partial oxidation of methane(POM)to syngas demonstrated the existence of CH_x(a)and H_xCO(a)adspecies on the functioning Ni-catalysts, Several designed experimental investigations on the reactivities of methane with CO_2 and with O_2,respectively,over the Ni-catalysts, and of CO_2 with the prereduced Ni-catalyst,ats well as of the deposited carbon with CO_2 and with O_2,respectlvely,liave been carried out and the reLqults were unfavorable to the two-step mechanistic interpretation proposed for the POM reaction. By means of tlie BOC-MP Approach,energetics of a set of elementary reactions,which may be involved in the POM process,on the clean(111)surface of Ni,Fe,Cu and Pd, re- spectively,has been studied.The result;of the experiments and the calculation of the present work favor the direct catalytic dissociation-plus-surface oxidation-plus-further debdrogenation mechanism as the dominant pathway making major contribution to the POM reaction.展开更多
Properties of various defects of He and H atoms in W-Ta alloys are investigated based on density functional theory. The tetrahedral interstitial site is the most configured site for self-interstitial He and H in W and...Properties of various defects of He and H atoms in W-Ta alloys are investigated based on density functional theory. The tetrahedral interstitial site is the most configured site for self-interstitial He and H in W and W-Ta alloys. Only a single He atom favors a substitutional site in the presence of a nearby vacancy. However, in the coexistence of He and H atoms in the presence of the vacancy, the single H atom favors the tetrahedral interstitial site（TIS） closest to the vacancy, and the He atom takes the vacancy center. The addition of Ta can reduce the formation energy of TIS He or H defects. The substituted Ta affects the charge density distribution in the vicinity of the He atom and decreases the valence electron density of the H atoms. A strong hybridization of the H s states and the nearest W d state s exists in W（53）He1 H1 structure. The sequence of the He p projected DOS at the Fermi energy level is in agreement with the order of the formation energy of the He-H pair in the systems.展开更多
基金supported by the National Natural Science Foundation of China(NFSC No.22122805,U21A20310,22075090,and 22278164)the Science and Technology Program of Guangzhou,China(No.2024A04J1540)。
文摘A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perovskite solar cells(C-PSCs),which have a large interface energy level mismatch.The regulation of perovslite's surface energetics is an effective way to improve the V_(bi)and promote charge extraction,which is typically achieved by organic molecules.However,the insulating nature of organic molecules also negatively hinders charge transfer,resulting in a contradiction of"extraction-transport".Quantum dots(Q.Ds)have great potential for energetics regulation of perovskite film due to their semiconductor properties and inherent large dipole moments,but have not yet been explored.In this work,we propose a strategy of discrete embedding semiconductor QDs at the surface grain boundaries of the perovskite film to regulate surface energetics.The QDs change the energetics of the perovskite film surface,transforming the surface energetics from n-to p-type,thus constructing p-n homojunction at the interface.This significantly enhances the Vbi at the perovskite/carbon electrode interface,promoting hole extraction.In addition,the embedded discrete distribution of QDs at the upper surface grain boundaries ensures efficient transport of the extracted holes to the carbon electrode,overcoming the contradiction of"extraction-transport"for traditional energetics control strategies.Consequently,the fabricated planar HTL-free C-PSCs achieve an efficiency of 20.10%(certified 19.8%),which is one of the highest values reported for this kind of device.
基金supported by the National Natural Science Foundation of China(No.41876015)。
文摘Ocean mixing is a consequence of essential dynamic processes such as internal tides and lee waves that occur near the seafloor topography.Internal tides and lee waves are generated by barotropic tidal currents and geostrophic flows,respectively.Ocean current is composed of multiple flows;thus,internal tides and lee waves occur concurrently in the real ocean.In this paper,the Massachusetts Institute of Technology general circulation model(MITgcm)is used to conduct 2D numerical experiments.By varying background flow intensities,the energy and dissipation relationship between internal tides and lee waves are investigated.The results reveal that the internal tide beams become asymmetric due to the influence of Doppler shift.The lee wave structure gradually leads the wave field when the background flow velocity rises constantly.The presence of a background flow increases the energy portion of the high-mode wave by up to 15%-20%.Moreover,strong shear,owing to the background flow,considerably increases dissipation.When the background flow velocity is higher than the barotropic tidal current velocity,the isopycnal overturn triggered by the lee wave generates a dissipation of the same order of magnitude as the shear.
文摘Gravitational potential energy （GPE） source and sink due to stirring and cabbeling associated with sigma dif fusion/ advection is analyzed. It is shown that GPE source and sink is too big, and they are not closely linked to physical property distribution, such as temperature, salinity and velocity. Although the most frequently quoted advantage of sigma coordinate models are their capability of dealing with topography; the exces sive amount of GPE source and sink due to stirring and cabbeling associated with sigma diffusion/advec tion diagnosed from our analysis raises a very serious question whether the way lateral diffusion/advection simulated in the sigma coordinates model is physically acceptable. GPE source and sink in three coordinates is dramatically different in their magnitude and patterns. Overall, in terms of simulating lateral eddy diffu sion and advection isopycnal coordinates is the best choice and sigma coordinates is the worst. The physical reason of the excessive GPE source and sink in sigma coordinates is further explored in details. However, even in the isopycnal coordinates, simulation based on the Eulerian coordinates can be contaminated by the numerical errors associated with the advection terms.
文摘Gravitational Potential Energy （GPE） change due to horizontal/isopycnal eddy diffusion and advection is examined. Horizontal/isopycnal eddy diffusion is conceptually separated into two steps： stirring and sub scale diffusion. GPE changes associated with these two steps are analyzed. In addition, GPE changes due to stirring and subscale diffusion associated with horizontal/isopycnal advection in the Eulerian coordinates are analyzed. These formulae are applied to the SODA data for the world oceans. Our analysis indicates that horizontal/isopycnal advection in Eulerian coordinates can introduce large artificial diffusion in the model. It is shown that GPE source/sink in isopycnal coordinates is closely linked to physical property distribution, such as temperature, salinity and velocity. In comparison with z-coordinates, GPE source/sink due to stir ring/cabbeling associated with isopycnal diffusion/advection is much smaller. Although isopycnal coordi nates may be a better choice in terms of handling lateral diffusion, advection terms in the traditional Eule rian coordinates can produce artificial source of GPE due to cabbeling associated with advection. Reducing such numerical errors remains a grand challenge.
文摘Initially thought to be an opioid receptor subtype, Sigma-1 receptors (S1R) are now known to be unique proteins that have chaperone-like properties. As such, they play critical roles in cellular signaling, homeostasis, and cell survival. These roles offer significant insight for understanding homeostasis of normal physiologic processes, and the pathophysiologic consequences of disruption of normal function. Because of the broad nature of chaperone action, S1R agonists and antagonists represent potential drug discovery goals for the pharmacotherapeutic treatment of a variety of disorders that result from dysfunctional proteins. The present study summarizes the S1R as a pharmacologic chaperone crucial for protein folding and cellular homeostasis. Through literature review and thermodynamic analysis, it explores how S1R stabilizes target proteins, influencing neuroprotection and potential drug therapies. The binding of chaperones to target proteins is thermodynamically favorable, offering insights into treating diseases linked to protein misfolding.
基金supported by the National Natural Science Foundation of China (21573232, 21576251, 21676269)National Key Projects for Funda-mental Research and Development of China (2016YFA0202801)Department of Science and Technology of Liaoning province under contract of 2015020086–101~~
文摘The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved heat is helpful in terms of understanding the nature of the interactions be- tween the catalyst and the adsorbed species, and provides insights into the reactivity of the catalyst. Although various techniques have previously been applied to assessments of evolved heat, direct measurements using a Tian-Calvet microcalorimeter are currently the most reliable method for this purpose. In this review, we summarize the relationship between the adsorption/reaction energetics determined by microcalorimetry and the reactivities of supported catalysts, and examine the im- portant role of microcalorimetry in understanding catalytic performance from the energetic point of view.
文摘Two important nonlinear properties of seawater thermodynamics linked to changes of water density, cab beling and elasticity （compressibility）, are discussed. Eddy diffusion and advection lead to changes in den sity; as a result, gravitational potential energy of the system is changed. Therefore, cabbeling and elasticity play key roles in the energetics of lateral eddy diffusion and advection. Vertical eddy diffusion is one of the key elements in the mechanical energy balance of the global oceans. Vertical eddy diffusion can be con ceptually separated into two steps： stirring and subscale diffusion. Vertical eddy stirring pushes cold/dense water upward and warm/light water downward; thus, gravitational potential energy is increased. During the second steps, water masses from different places mix through subscale diffusion, and water density is increased due to cabbeling. UsingWOA01 climatology and assuming the vertical eddy diffusivity is equal to a constant value of 2x103 pa2/s, the total amount of gravitational potential energy increase due to vertical stirring in the world oceans is estimated at 263 GW. Cabbeling associated with vertical subscale diffusion is a sink of gravitational potential energy, and the total value of energy lost is estimated at 73 GW. Therefore, the net source of gravitational potential energy due to vertical eddy diffusion for the world oceans is estimated at 189 GW.
基金The project supported by the National Science Foundation(USA)through grant MSS-9258115by the National Natural Science Foundation of China
文摘An evolving material structure is in a non-equilibrium state, with free energy expressed by the generalized coordinates. A global approach leads to robust computations for the generalized thermodynamic forces. Those forces drive various kinetic processes, causing dissipation at spots, along curves, surfaces and interfaces, and within volumetric regions. The actual evolution path, and therefore the final equilibrium state, is determined by the energetics and kinetics. A virtual work principle Links the free energy landscape and the kinetic processes, and assigns a viscous environment to every point on the landscape. The approach leads to a dynamical system that governs the evolution of generalized coordinates. The microstructural evolution is globally characterized by a basin map in the coordinate space; and by a diversity map and a variety map in the parameter space. The control of basin boundaries raises the issue of energetic and kinetic bifurcations. The variation of basin boundaries under different sets of controlling parameters provides an analytical way to plot the diversity maps of structural evolution.
文摘Study of oceanic circulation and climate requires models which can simulate tracer eddy diffusion and ad vection accurately. It is shown that the traditional Eulerian coordinates can introduce large artificial hori zontal diffusivity/viscosity due to the incorrect alignment of the axis. Therefore, such models can smear sharp fronts and introduce other numerical artifacts. For simulation with relatively low resolution, large lateral diffusion was explicitly used in models; therefore, such numerical diffusion may not be a problem. However, with the increase of horizontal resolution, the artificial diffusivity/viscosity associated with hori zontal advection in the commonly used Eulerian coordinates may become one of the most challenging ob stacles for modeling the ocean circulation accurately. Isopycnal eddy diffusion （mixing） has been widely used in numerical models. The common wisdom is that mixing along isopycnal is energy free. However, a careful examination reveals that this is not the case. In fact, eddy diffusion can be conceptually separated into two steps： stirring and subscale diffusion. Due to the thermobaric effect, stirring, or exchanging water masses, along isopycnal surface is associated with the change of GPE in the mean state. This is a new type of instability, called the thermobaric instability. In addition, due to cabbeling subscale diffusion of water parcels always leads to the release of GPE. The release of GPE due to isopycnal stirring and subscale diffusion may lead to the thermobaric instability.
基金the National Natural Science Foundation of China (10472060)Research Grants Council of the Hong Kong Special Administrative Region (9041145)+1 种基金Shanghai Municipal Education Commission Scientific Research Project (07ZZ07)Shanghai Leading Academic Discipline Project (Y0103)
文摘Nonlinear three-dimensional vibration of axially moving strings is investigated in the view of energetics. The governing equation is derived from the Eulerian equation of motion of a continuum for axially accelerating strings. The time-rate of the total mechanical energy associated with the vibration is calculated for the string with its ends moving in a prescribed way. For a string moving in a constant axial speed and constrained by two fixed ends, a conserved quantity is proved to remain unchanged during three-dimensional vibration, while the string energy is not conserved. An approximate conserved quantity is derived from the conserved quantity in the neighborhood of the straight equilibrium configuration. The approximate conserved quantity is applied to verify the Lyapunov stability of the straight equilibrium configuration. Numerical simulations are performed for a rubber string and a steel string. The results demonstrate the variation of the total mechanical energy and the invariance of the conserved quantity.
基金supported by the National Basic Research and Development Project (973 program) of China (Grant No. 2015CB452805)the National Natural Science Foundation of China (Grant No. 41375068)partly supported by the National Science Foundation (Grant No. AGS-1326524)
文摘A 72-h high-resolution simulation of Supertyphoon Rammasun （2014） is performed using the Advanced Research Weather Research and Forecasting model. The model covers an initial 18-h spin-up, the 36-h rapid intensification （RI） period in the northern South China Sea, and the 18-h period of weakening after landfall. The results show that the model reproduces the track, intensity, structure of the storm, and environmental circulations reasonably well. Analysis of the surface energetics under the storm indicates that the storm＇s intensification is closely related to the net energy gain rate （eg）, defined as the difference between the energy production （PD） due to surface entropy flux and the energy dissipation （Ds） due to surface friction near the radius of maximum wind （RMW）. Before and during the RI stage, the ~：g is high, indicating sufficient energy supply for the storm to intensify. However, the Sg decreases rapidly as the storm quickly intensifies, because the Ds increases more rapidly than the PD near the RMW. By the time the storm reaches its peak intensity, the Ds is about 20% larger than the PD near the RMW, leading to a local energetics deficit under the eyewall. During the mature stage, the PD and Ds can reach a balance within a radius of 86 km from the storm center （about 2.3 times the RMW）. This implies that the local PD under the eyewall is not large enough to balance the Ds, and the radially inward energy transport from outside the eyewall must play an important role in maintaining the storm＇s intensity, as well as its intensification.
基金Supported by the Key Program of National Natural Science Foundation of China(No.41030855)the National High Technology Research and Development Program of China(863 Program)(No.2008AA09A402)
文摘A fully nonlinear,three-dimensional nonhydrostatic model driven by four principal tidal constituents(M2,S2,K1,and O1) is used to investigate the spatial-temporal characteristics and energetics of internal tides in Luzon Strait(LS).The model results show that,during spring(neap) tides,about 64(47) GW(1 GW=109 W) of barotropic tidal energy is consumed in LS,of which 59.0%(50.5%) is converted to baroclinic tides.About 22(11) GW of the derived baroclinic energy flux subsequently passes from LS,among which 50.9%(54.3%) flows westward into the South China Sea(SCS) and 45.0%(39.7%) eastward into the Pacific Ocean,and the remaining 16(13) GW is lost locally owing to dissipation and convection.It is revealed that generation areas of internal tides vary with the spring and neap tide,indicating different source areas for internal solitary waves in the northern SCS.The region around the Batan Islands is the most important generation region of internal tides during both spring and neap tides.In addition,the baroclinic tidal energy has pronounced seasonal variability.Both the total energy transferred from barotropic tides to baroclinic tides and the baroclinic energy flux flowing out of LS are the highest in summer and lowest in winter.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.11405011 and 11475033).
文摘The basic energy balance model is applied to analyze the hohlraum energetics data from the Shenguang(SG)series laser facilities and the National Ignition Facility(NIF)experiments published in the past few years.The analysis shows that the overall hohlraum energetics data are in agreement with the energy balance model within 20%deviation.The 20%deviation might be caused by the diversity in hohlraum parameters,such as material,laser pulse,gas filling density,etc.In addition,the NIF's ignition target designs and our ignition target designs given by simulations are also in accordance with the energy balance model.This work confirms the value of the energy balance model for ignition target design and experimental data assessment,and demonstrates that the NIF energy is enough to achieve ignition if a 1D spherical radiation drive could be created,meanwhile both the laser plasma instabilities and hydrodynamic instabilities could be suppressed.
文摘Measurements were made on the contents of protein, lipid, glycogen (PLG) and water, and on caloric values and amino acids, in muscle of three mudskippers Periophthalmis cantonensis, Scarteiaos viridis and Boleophthalmus pectinirostris collected from Haicang, Xiamen. The essential amino acids (EAA) for these fishes were also studied with radioisotopic trace method. The results showed: (1) The content of each component in tested fish muscles differed slightly, and protein was the most important component making up from 6.685% to 9.891% of the wet weight (about 44.21%-50.45% of dry weight); (2) Energy calculated from the sum of protein, lipid and glycogen in wet muscle was low (<4.3kJ/g) in these fishes, especially in B. pectinirostris (<3.1 kJ/g); the ratios of energy to protein content (E/P) also were low (<39.873 -45.535kJ/g); (3) Seventeen amino acids were determined in these three fishes. The content of the same amino acid (among the seventeen) tested in different species and sexes varied slightly. The amounts of methionine, phenylalanine lysine, arginme, histidine, threonine isoleucine and leucine which are indispensable for the needs of human beings and animals were relative-ly high, accounting for 47.35%-48.06% of the total amino acid content. (4) Leucine, isoleucine, arginme, lysine, phenylalanine, tryptophan, methionine, histidine, threonine, and valine, are essential in the diet of the three mudskippers as the radioisotopic trace method using D-[U-^(14) C]-glucose showed little or no radioactivity was incorporated into these ten amino acids.
基金support from the National Key Research and Development Program of China(Grant no.2019YFA0209900)the National Natural Science Foundation of China(Grant nos.12075179 and 12105219)+2 种基金the China Postdoctoral Science Foundation(Grant no.2021M702583)the Innovative Scientific Program of China National Nuclear Corporation,the Innovation Program of Nuclear Power Institute of China(No.KJCX-2022-1-04)the LiYing Program of the Institute of Mechanics,Chinese Academy of Sciences(Grant no.E1Z1011001).
文摘The stability of small vacancy clusters including divacancy,trivacancy and tetravacancy has been studied in body-centered cubic high-entropy alloy Nb_(0.75)ZrTiV_(0.5) in structures of random solid solution and short-range order by first-principles calculations and molecular dynamics simulations.Different from conventional body-centered cubic metals,the tightly bound configurations have a lower structural stability and are not preferred energetically in the studied high-entropy alloy.Instability of vacancy configurations leads to vacancy-atom exchanges that favor less compact configurations.The formation energy of small vacancy clusters is much smaller than its constituent elements of Nb and V due to the large structural adjustment induced by severe local lattice distortion.The difference in local lattice distortion and elemental arrangement in the vacancy neighborhood leads to significant site-to-site variation in vacancy cluster energy and configuration.The formation energy has a strong correlation with the local energy state of the vacancy configuration and the extent of structural relaxation.Compared to random solid solution,the structure of short-range order has a higher stability for the most compact cluster configurations and tends to have higher vacancy cluster formation energy.According to classical molecular dynamics simulations of cluster diffusion at high temperature,the studied high-entropy alloy has a higher probability of cluster dissociation compared to Nb and V.The unconventional energetics of small vacancy clusters is expected to have a profound impact on their generation,diffusion,dissociation,coalescence,as well as the defect microstructure evolution during irradiation.
文摘In development of baroclinic disturbances, baroclinity of basic temperature field varies with conversion of available potential energy. The growth rate which depends on the baroclinity varies as well. However, in previous linear theories, the growth rate was considered constant, so development of disturbances was not constrained by energy sources in the linear theories. In terms of energy conservation and conversion in an isolated atmosphere, we may study the variations in the baroclinity and growth rate and draw the corresponding pictures of perturbation developments in the varying environments. The amplification for the most unstable Eady wave is discussed as an example. It will be found that growth of baroclinic perturbations constrained by energy conservation is significantly different from the growth at the initial constant rate after mature stage.
基金the National Natural Science Foundation of China(No.21673231,No.21673234,No.21688102,and No.21873097)the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(No.XDB17000000)+1 种基金Dalian Institute of Chemical Physics(DICP DCLS201702)China Postdoctoral Science Foundation(No.2018M641718 and No.2018M641719).
文摘The structures,energetics,and infrared(IR)spectra of the cationic monomethylamine-water clusters,[(CH3NH2)(H2O)n]^+(n=1-5),have been studied using quantum chemical calculations at the MP2/6-311+G(2d,p)level.The results reveal that the formation of protontransferred CH2NH3+ ion core structure is preferred via the intramolecular proton transfer from the methyl group to the nitrogen atom and the water molecules act as the acceptor for the O…HN hydrogen bonds with the positively charged NH3^+ moiety of CH2NH3^+,whose motif is retained in the larger clusters.The CH3NH2^+ ion core structure is predicted to be less energetically favorable.Vibrational frequencies of CH stretches,hydrogen-bonded and free NH stretches,and hydrogen-bonded OH stretches in the calculated IR spectra of the CH2NH3^+ and CH3NH2^+ type structures are di erent from each other,which would a ord the sensitive probes for fundamental understanding of hydrogen bonding networks generated from the radiation-induced chemical processes in the[(CH3NH2)(H2O)n]+complexes.
基金This work was supported by the Italian Ministry of University and Scientific Research(PRIN 2017)the University of Padua(SID 2019)the UNIPD Funds for Research Equipment(2015).
文摘Mitochondria and neuronal activity:The brain is one of the highest energy demanding organs,consuming~20%of the total ATP produced by the whole body.Importantly,neurons mainly rely on ATP synthesized by mitochondrial bioenergetics and neuronal activity is strictly dependent on specific mitochondrial localization at synapses,sites consuming a high amount of energy requested for both pre-and post-synaptic processes.Here,mitochondria produce ATP and buffer Ca^2+rises,two essential processes for neurotransmission and generation of membrane potential along the axon(Magistretti and Allaman,2015).
文摘he characteristic study,by means of in-situ IR spectroscopy, of chemisorbed species on the Ni-catalysts for the partial oxidation of methane(POM)to syngas demonstrated the existence of CH_x(a)and H_xCO(a)adspecies on the functioning Ni-catalysts, Several designed experimental investigations on the reactivities of methane with CO_2 and with O_2,respectively,over the Ni-catalysts, and of CO_2 with the prereduced Ni-catalyst,ats well as of the deposited carbon with CO_2 and with O_2,respectlvely,liave been carried out and the reLqults were unfavorable to the two-step mechanistic interpretation proposed for the POM reaction. By means of tlie BOC-MP Approach,energetics of a set of elementary reactions,which may be involved in the POM process,on the clean(111)surface of Ni,Fe,Cu and Pd, re- spectively,has been studied.The result;of the experiments and the calculation of the present work favor the direct catalytic dissociation-plus-surface oxidation-plus-further debdrogenation mechanism as the dominant pathway making major contribution to the POM reaction.
基金Supported by the National Natural Science Foundation of China under Grant No 11605007the Funding from the China Scholarship Council under Grant No 201506465019
文摘Properties of various defects of He and H atoms in W-Ta alloys are investigated based on density functional theory. The tetrahedral interstitial site is the most configured site for self-interstitial He and H in W and W-Ta alloys. Only a single He atom favors a substitutional site in the presence of a nearby vacancy. However, in the coexistence of He and H atoms in the presence of the vacancy, the single H atom favors the tetrahedral interstitial site（TIS） closest to the vacancy, and the He atom takes the vacancy center. The addition of Ta can reduce the formation energy of TIS He or H defects. The substituted Ta affects the charge density distribution in the vicinity of the He atom and decreases the valence electron density of the H atoms. A strong hybridization of the H s states and the nearest W d state s exists in W（53）He1 H1 structure. The sequence of the He p projected DOS at the Fermi energy level is in agreement with the order of the formation energy of the He-H pair in the systems.
