Exchange Energy Research Articles

Sulfur Oxidation State and Substituents Influenced Multifunctional Organic Luminophores in BTP Core for OLEDs: A Computational Study on RTP, TADF Emitter and Sensitizer.

The exploration of triplet excitons in thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) molecules has become a subject of significant attention and interest in recent studies. This study employed density functional theory (DFT) and time-dependent DFT theoretical methods to delve into the intricate relationship between the molecular structure and properties of molecules designed with the oxidation of sulfur atoms (S, SO, and SO2) in benzothiazinophenothiazine (BTP) core units. The calculations revealed that as the oxidation state of the sulfur atom increased, the BTP derivatives exhibited elevated ionization potentials (IPs), electron affinities (EAs), and triplet energies (ET), accompanied by reduced reorganization energies (λ), singlet energies (ES), and a S1-T1 energy gap (ΔEST). Additionally, the decrease in the exchange energy prompts a shift in the excited-state properties of molecules, transitioning them from hybridized local and charge transfer (HLCT) to charge transfer (CT) in the S1 state while maintaining their HLCT character in the T1 state. The sulfur oxidation process systematically decreases spin-orbit coupling magnitudes in the S1-T1 and T1-S0 pathways while increasing the KRISC rate, signifying a reduced propensity for phosphorescence radiative decay in oxidized molecules. Thorough investigations have explored the screening effect and orbital mixing of lone pair electrons in sulfur atoms, satisfying the desired criteria for a multifunctional RTP, TADF emitter and sensitizer.

Interconnecting industrial multi-microgrids using bidirectional hybrid energy links

Sharing and exchange energy among nearby industrial microgrids are crucial, especially with high energy requirements for their production targets and costly energy storage systems that may be oversized for their operations. Facilitating energy exchange can provide an economic advantage for industrial production by utilizing cheaper energy sources and reducing production costs. This manuscript presents an efficient approach for transferring large energy packets with minimal energy losses using high-voltage direct current (HVDC) energy transmission. The manuscript methodology focuses on implementing an industrial multi-microgrid using a modular multilevel converter. This converter utilizes two power link channels: a three-phase AC and an HVDC link, creating a hybrid energy transmission between microgrids. When a substantial amount of energy to transfer, the HVDC method enhances overall efficiency by reducing copper losses and mitigating issues associated with the AC link, such as harmonics and skin effects. The modular multilevel converter topology offers high flexibility and the use of fewer converters. Additionally, the HVDC link eliminates distance restrictions for energy transfer between industrial microgrids. A case study illustrates the functionality of this topology, demonstrating optimized power transfer and decreased energy losses. This methodology allows industrial microgrids to enhance energy efficiency and productivity while minimizing operational costs.

Thermomechanics of ferri-antiferromagnetic phase transition in finitely-strained rocks towards paleomagnetism

The thermodynamic model of visco-elastic deformable magnetic materials at finite strains is formulated in a fully Eulerian way in rates with the aim to describe thermoremanent paleomagnetism in crustal rocks. The Landau theory applied to a ferro-to-para-magnetic phase transition, the gradient theory for magnetization (leading to exchange energy) with general mechanically dependent coefficient, hysteresis in magnetization evolution by Gilbert equation involving objective corotational time derivative of magnetization, and demagnetizing field are considered in the model. The Jeffreys viscoelastic rheology is used with temperature-dependent creep to model solidification or melting transition. The model complies with energy conservation and the Clausius-Duhem entropy inequality.

Study of ferromagnetism, and thermoelectric behavior of double perovskites K2Z(Cl/Br)6 (Z = Ta, W, Re) for spintronic, and energy application

Spintronic is the developing technology which probes the properties of quantum devices with spin of electrons which reduce the size and enhance its speed. Therefore, here the role of 5d electrons and thermoelectric characteristics of double perovskites (DPs) K2ZCl/Br6 (Z = Ta, W, Re) elaborated comprehensively by density functional theory (DFT). The Heisenberg model spin polarization density (SP) has been applied to evaluate the Curie temperature (Tc) and spin polarization factor. The tolerance factor (tF) and formation energy (ΔH) have been calculated to confirm the stability of structures. Ferromagnetism has been discussed in terms of spin polarization, crystal field energy (ΔCF) and exchange energies (Δ(d), Δ(pd)). The double exchange mechanism, and exchange constants ensure the role of electrons spin in ferromagnetism instead of segregation of transition metal ions. The transferring of magnetic moments of transitions metals to nonmagnetic sites (K, Cl, Br) show the exchange of spin of electrons and integer values of total magnetic moment show 100 % spin polarization. Finally, the transport properties are studied in standings of electrical and thermal conductivities. The large value of Seebeck coefficient and power factor ensure the importance of studied DPs for thermoelectric generators.

Intestinal FFA2 promotes obesity by altering food intake in Western diet-fed mice.

Short-chain fatty acids (SCFAs) are key nutrients that play a diverse set of roles in physiological function, including regulating metabolic homeostasis. Generated through the fermentation of dietary fibers in the distal colon by the gut microbiome, SCFAs and their effects are partially mediated by their cognate receptors, including free fatty acid receptor 2 (FFA2). FFA2 is highly expressed in the intestinal epithelial cells, where its putative functions are controversial, with numerous in vivo studies relying on global knockout mouse models to characterize intestine-specific roles of the receptor. Here, we used the Villin-Cre mouse line to generate a novel, intestine-specific knockout mouse model for FFA2 (Vil-FFA2) to investigate receptor function within the intestine. Because dietary changes are known to affect the composition of the gut microbiome, and can thereby alter SCFA production, we performed an obesogenic challenge on male Vil-FFA2 mice and their littermate controls (FFA2-floxed, FFA2fl/fl) to identify physiological changes on a high-fat, high-sugar 'Western diet' (WD) compared to a low-fat control diet (CD). We found that the WD-fed Vil-FFA2 mice were transiently protected from the obesogenic effects of the WD and had lower fat mass and improved glucose homeostasis compared to the WD-fed FFA2fl/fl control group during the first half of the study. Additionally, major differences in respiratory exchange ratio and energy expenditure were observed in the WD-fed Vil-FFA2 mice, and food intake was found to be significantly reduced at multiple points in the study. Taken together, this study uncovers a novel role of intestinal FFA2 in mediating the development of obesity.

Optimization of dairy cows diets for crude protein

The influence of the composition of the diet on the productive indicators of cows, in particular on the chemical composition of milk, is analyzed. A reduction in the supply of succulent feed to 46.6% of the total energy nutrition and an increase in the proportion of concentrates (up to 53.4% of the exchange energy) for dairy cows were unacceptable. During the study, the level of milk productivity of black-andwhite cows increased very slightly – by 0.7 kg head /day. It is possible that in the first days of the change of the cow's diet, the total gross milk yield increases, but this period does not last long, and soon cows with acidosis and other metabolic disorders appear on the farm. The increase in the level of concentrated feed in the farm negatively affected the physico-chemical composition of milk, which became unsorted. A negative consequence of the change in the diet of cows was a deterioration in the quality of milk. Thus, the ratio of «fat – protein» has changed in the opposite direction, the urea content has increased (to 48.58–52.97 mg / 100 ml), the titrated acidity of milk has increased (to 19.49–21.04 °T) and the content of somatic cells in milk (to the level of 354.41–450.54 thousand / cm3) in cows of all lactations.

Controlling electromagnetic and mechanical behaviors of geopolymer matrix with nano-SiO2@Fe3O4 magnetofluid for soft magnetic applications

Nano-SiO2@Fe3O4 magnetofluid modified geopolymer (NMMG) is presenting promising application potential in the field of magnetic building materials by virtue of its high magnetic permeability. This work aims to reveal the modification mechanisms of nano-SiO2@Fe3O4 magnetofluid on the electromagnetic and mechanical behaviors of geopolymer matrix, thus providing theoretical guidance for the engineering applications of NMMG. The results show that the introduction of nano-SiO2@Fe3O4 magnetofluid enhances the magnetic exchange energy between adjacent magnetic moments inside the geopolymer, thus weakening the coercivity by intensifying the rotation of magnetic domains inside the geopolymer, which provides a new idea for the application of NMMG in the field of soft magnetic construction materials. In addition, when the concentration of nano-SiO2@Fe3O4 magnetofluid reaches 9.4 vol%, good balance is found in the electromagnetic and mechanical behaviors of NMMG material. In that regard, NMMG can achieve satisfactory mechanical performance, ensuring as well low eddy current and hysteresis losses under alternating magnetic field, which reflects its great potential in soft magnetic applications.

Anisotropies of thermal conductivity of SrIr4In2Ge4 and EuIr4In2Ge4 crystals: Manifestation of coupling of phonons with europium spin 1D fluctuations?

We report the results of measurements of thermal conductivity coefficient dependence on temperature of single crystals of SrIr4In2Ge4 and EuIr4In2Ge4. The measurements were carried out over the temperature range of ∼5–300 K. The EuIr4In2Ge4 crystal, unlike its strontium analog SrIr4In2Ge4, shows an amazing anisotropy: At low temperatures, it displays significantly smaller thermal conductivity in the ab plane than in the direction of c axis, while at the high ones the thermal conductivity in the direction perpendicular to the c axis increases well above that of in the c axis. The observed phenomena may be a result of the interaction of phonons with 1D chains of short-range ordered magnetic moment of europium atoms and the exchange energy between the chains in the paramagnetic phase of EuIr4In2Ge4.

Двухукосное использование многолетних кормовых агроценозов в условиях северных регионов России

Abstract. The purpose of the research is to study cereal-legume agrocenoses with long-term two-cutting use in the conditions of the northern territories of the Arkhangelsk region. Methods. The studies were carried out according to generally accepted methods in the period from 2019 to 2022. in a field experiment on soddy-podzolic sandy loamy soil. The object of research is perennial agrocenoses of perennial grasses. Results. The prospects for the use of cane fescue in a two-component grass mixture in the conditions of the northern region of Russia have been established. Agrophytocenoses, created in a mixture of this crop with red clover, allow for three years of two-cutting use to consistently obtain from 10.19 to 11.71 t/ha of dry matter with a content of exchange energy and crude protein of 90.53 - 129.01 GJ and 1 ,13 - 1.51 tons. There is a negative trend - an annual decrease in the participation of red clover in the phytocenosis. So, if in the first year of life in the structure of the crop of green mass contained up to 73% of red clover, then by the third year of the two-cutting use of the herbage, this value decreased to an average of 17%. Blue alfalfa in herbage with cereal grasses in the first year of life proved to be a promising crop with good plant development and content in the crop structure from 59% to 67%, but after the first overwintering, its content in the phytocenosis biomass decreased to 6–8%, and in in subsequent years, it completely fell out of the herbage. Scientific novelty. For the first time in the natural and climatic conditions of the north of the Arkhangelsk region, grass stands created from reed fescue mixed with red clover of local selection were studied. The features of growth and development of fodder crops in such agrocenoses for 3 years of two-cutting use were revealed, the productivity and nutritional value of the green mass was assessed.

Do Local and International Shocks Matter in the Interconnectedness amid Exchange Rates and Energy Commodities? Insights into BRICS Economies

The study examined the interdependence structure among energy (brent, natural gas and petroleum) commodities returns, crude oil implied volatility, and exchange rate returns and volatilities in the context of BRICS across time and/or frequencies. The wavelet approaches (bi-wavelet, partial wavelet and wavelet multiple) were employed for the period from May 07, 2012, to March 31, 2021. It was revealed that co-movements between exchange rate returns and energy commodities were negative and significant at certain times and frequencies. In this case, causality emanated from exchange rate returns. Moreover, in most instances, implied volatilities strongly impacted the exchange rate and energy interconnectedness returns. We found strong integration levels among the financial time series with Petroleum having the most likelihood to lead or lag. Findings from the study imply that co-movements between exchange rate returns and energy commodities are heterogeneous and adaptive. Also, local shocks (exchange rate volatilities), have the greatest spillover effect between exchange rate returns and energy commodities relative to implied crude oil volatility. This is the first study that employs the wavelet approaches to investigate the conditional effects of local and external shock on the comovement between exchange rate returns and energy commodities’ returns.

Cation-ordered Ni-rich positive electrode material with superior chemical and structural stability enabled by atomic substitution for lithium-ion batteries

Ni-rich layered oxides are considered as the most promising cathode materials for lithium-ion batteries (LIBs) due to their high specific capacity and low cost. However, the disordered Li/Ni mixing greatly affects their structural stability and electrochemical performance, thus hindering their wide application in commercial LIBs. Aiming to inhibit the premature death of Ni-rich layered oxides originated from the disordered Li/Ni mixing, atomic substitution of transition metal ions in LiNi0.83Co0.11Mn0.06O2 with high-valence metal molybdenum ions (denoted as Mo-NCM) is proposed in this work. The structure evolution of the as-prepared Mo-NCM caused by molybdenum substitution and the stability of Mo-NCM cathodes are comprehensively studied. Integrating experimental characterization with calculation results, it is found that the partial substitution of transition metal ions with Mo6+ ions can induce cation ordering and promote Li+ diffusion dynamics. Moreover, Mo6+ cations can act as the pillar to prevent local collapse and structural distortion, thus maintaining structural stability of the material. Furthermore, the formation of strong Mo-O bond between molybdenum and oxygen element can stabilize lattice oxygen and enhance the chemical stability of Ni-rich cathode. In addition, molybdenum modification can effectively reduce the exchange energy of Li+/Ni2+ and increase oxygen vacancy formation energy, further enhancing structural stability and promoting the kinetics of Li+ diffusion, and eventually enhancing the electrochemical performance of Mo-NCM based Li-ion batteries. The capacity retention of LIBs with 1 mol% Mo-NCM cathode can reach 98.67% after 200 cycles at 1C. This study provides a new insight into enhancing the chemical and structural robustness of Ni-rich cathode electrode materials.

Anisotropic microwave response in Cr1∕3TaS2 hosting chiral magnetic soliton

Chromium-intercalated hexagonal Cr1∕3TaS2 possesses exotic properties, such as high-temperature magnetic soliton, crossover of critical behavior, and nontrivial magnetism. In this study, we employ the electron spin resonance (ESR) technique to modulate and study the chiral magnetic soliton lattice (CSL) in Cr1∕3TaS2 using microwave at X-band. The experimental results show that Cr1∕3TaS2 has a particularly strong microwave response when H⊥c but very weak feedback when H//c, revealing an anisotropic microwave response. When H⊥c, the resonance peak at lower fields results from the surface barrier induced by the competition between Dzyaloshinsky–Moriya interaction, Zeeman energy, and exchange energy. The dominant resonance is caused by the ferromagnetic mode with the twisted region as the boundary condition, which transforms into a paramagnetic resonance above the phase transition temperature (TC). Furthermore, an unusual temperature dependence of ESR spectra is revealed. The crystalline electric field (CEF) excitation owing to large strong spin–orbit coupling results in the widening of the ESR linewidth above TC. Furthermore, an abrupt shift in the resonance field Hr2 and ESR linewidth ΔHPP2 is observed around TC, which is attributed to a sudden change in spin-exchange interactions and magnetic anisotropy around TC, as Cr1∕3TaS2 was previously observed for spin interaction transition from strong anisotropic 3D-Ising type to isotropic 3D-Heisenberg magnetic interaction below TC. This work demonstrates that the ESR can detect the CSL state and investigate materials with nontrivial magnetism.

Magnetic Skyrmions Under Confinement

We present a variational treatment of confined magnetic skyrmions in a minimal micromagnetic model of ultrathin ferromagnetic films with interfacial Dzylashinksii-Moriya interaction (DMI) in competition with the exchange energy, with a possible addition of perpendicular magnetic anisotropy. Under Dirichlet boundary conditions that are motivated by the asymptotic treatment of the stray field energy in the thin film limit we prove existence of topologically non-trivial energy minimizers that concentrate on points in the domain as the DMI strength parameter tends to zero. Furthermore, we derive the leading order non-trivial term in the Γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Gamma $$\\end{document}-expansion of the energy in the limit of vanishing DMI strength that allows us to completely characterize the limiting magnetization profiles and interpret them as particle-like states whose radius and position are determined by minimizing a renormalized energy functional. In particular, we show that in our setting the skyrmions are strongly repelled from the domain boundaries, which imparts them with stability that is highly desirable for applications. We provide explicit calculations of the renormalized energy for a number of basic domain geometries.

Exchange energies and density functionals for systems of fermions of arbitrary spin

Exchange energies and density functionals for systems of fermions of arbitrary spin

Role of 4d electrons in room temperature ferromagnetism, and thermoelectric properties of Sr2CrXO6 (X = Nb, Mo) for spintronic applications

The spintronic is an emerging technology which controls the properties of multifactional devices with spin of electrons. In present manuscript, Wien2k and Boltz Trap codes are used to explore electronic, magnetic, and thermoelectric characteristics of Sr2CrXO6 (X = Nb, Mo) double perovskites (DPs). The evaluation of energies released in paramagnetic (PM), antiferromagnetic (AFM), and ferromagnetic (FM) states assure the stability of FM states. Both the negative formation energy and the tolerance factor confirm structural and thermodynamic stability in FM states. The 100 % spin polarization was confirmed by both integer values of magnetic moment (MM) and the spin polarization factor. The values of exchange energy, double exchange model, hybridization of p-d states, and exchange constants are calculated to explore the nature of ferromagnetism and spin functionality. The effect of thermoelectric parameters on spin of electrons and thermoelectric performance are elaborated by thermal to electrical conductivity ratio, Seebeck coefficient and power factor.

Social media and optimization of the promotion of Lake Toba tourism destinations in Indonesia

Tourism is one of the largest contributors to Indonesia's foreign exchange earnings, surpassing taxation, energy, and gas. This study seeks to investigate the use of social media to optimize the promotion of Lake Toba as a tourist destination, which has been impacted by the COVID-19 pandemic. Using interview techniques and live field observations, it was discovered that social media, particularly the Instagram platform, play a significant role in promoting Lake Toba tourism. The Department of Culture and Tourism of the North Sumatra Province uses landscape photography as its primary promotion method, which has proved to be more effective and interesting than conventional methods such as the distribution of brochures or the use of manuals. The capture procedure and techniques for landscape photography were carried out by professional photographers in collaboration with the Department of Culture and Tourism of the North Sumatra Province. In addition to providing information, tourism_sumut's Instagram account functions as a platform to raise public awareness about Lake Toba tourism and as a promotional medium for North Sumatra's tourist attractions on an international scale. Department of Culture and Tourism of the North Sumatra Province collaborates with travel agencies and local communities to disseminate Lake Toba tourism information.

Social media and optimization of the promotion of Lake Toba tourism destinations in Indonesia

Tourism is one of the largest contributors to Indonesia's foreign exchange earnings, surpassing taxation, energy, and gas. This study seeks to investigate the use of social media to optimize the promotion of Lake Toba as a tourist destination, which has been impacted by the COVID-19 pandemic. Using interview techniques and live field observations, it was discovered that social media, particularly the Instagram platform, play a significant role in promoting Lake Toba tourism. The Department of Culture and Tourism of the North Sumatra Province uses landscape photography as its primary promotion method, which has proved to be more effective and interesting than conventional methods such as the distribution of brochures or the use of manuals. The capture procedure and techniques for landscape photography were carried out by professional photographers in collaboration with the Department of Culture and Tourism of the North Sumatra Province. In addition to providing information, tourism_sumut's Instagram account functions as a platform to raise public awareness about Lake Toba tourism and as a promotional medium for North Sumatra's tourist attractions on an international scale. Department of Culture and Tourism of the North Sumatra Province collaborates with travel agencies and local communities to disseminate Lake Toba tourism information.

Assisted heat transfer enhancement in non-Newtonian dielectric fluids based on ion conduction phenomena

Electric field-assisted technologies show prospects for heat removal in electronic cooling scenarios with electro-thermo-convection phenomena. The coupled multiphysics field model is built using the finite volume method, and two configurations (depending upon the orientation of the electric field and gravity) are investigated for different shear-thinning properties and polymer elasticities. The results demonstrate a remarkable impact on the heat exchange efficiency, energy budget, plume morphology, and force distribution features. Two key partitions (buoyancy or Coulomb force-dominated regions) can be divided by Rayleigh number Ra ≤ 103 and electric Reynolds number ReE ≤ 1.57. A heat transfer boost of 13.9 times and 5.0 times was obtained in the two arrangements vs no electric reinforcement. The shear-thinning shows a noticeable positive contribution, and the heat transfer efficiency can be modulated by polymer elasticity within a wide parameter range. A detailed evaluation of the interfacial forces reveals the nonmonotonic curves of fluid convection and energy inputs.

Kinetic Energy Exchanges between a Two-Dimensional Front and Internal Waves

Abstract Fronts and near-inertial waves (NIWs) are energetic motions in the upper ocean that have been shown to interact and provide a route for kinetic energy (KE) dissipation of balanced oceanic flows. In this paper, we study these KE exchanges using an idealized model consisting of a two-dimensional geostrophically balanced front undergoing strain-induced semigeostrophic frontogenesis and internal wave (IW) vertical modes. The front–IW KE exchanges are quantified separately during two frontogenetic stages: an exponential sharpening stage that is characterized by a low Rossby number and is driven by the imposed strain (i.e., mesoscale frontogenesis), followed by a superexponential sharpening stage that is characterized by an Rossby number and is driven by the convergence of the secondary circulation (i.e., submesoscale frontogenesis). It is demonstrated that high-frequency IWs quickly escape the frontal zone and are very efficient at extracting KE from the imposed geostrophic strain field through the deformation shear production (DSP). Part of the extracted KE is then converted to wave potential energy. On the contrary, NIWs remain locked to the frontal zone and readily exchange energy with the ageostrophic frontal circulation. During the exponential stage, NIWs extract KE from the geostrophic strain through DSP and transfer it to the frontal secondary circulation via the ageostrophic shear production (AGSP) mechanism. During the superexponential stage, a newly identified mechanism, convergence production (CP), plays an important role in the NIW KE budget. The CP transfers KE from the convergent ageostrophic secondary circulation to the NIWs and largely cancels out the KE loss due to the AGSP. This CP may explain previous findings of KE transfer enhancement from balanced motions to IWs in frontal regions of realistic ocean models. We provide analytical estimates for the aforementioned energy exchange mechanisms that match well the numerical results. This highlights that the strength of the exchanges strongly depends on the frontal Rossby and Richardson numbers. Significance Statement Fronts with large horizontal density and velocity gradients are ubiquitous in the upper ocean. They are generated by a process known as frontogenesis, which is often initialized by straining motions of mesoscale balanced circulations. Here we examine the energy exchanges between fronts and internal waves in an idealized configuration, aiming to elucidate the mechanisms that can drain energy from oceanic balanced circulations. We identify a new mechanism for energy transfers from the frontal circulation to near-inertial internal waves called convergence production. This mechanism is especially effective during the later stages of frontogenesis when the convergent ageostrophic secondary circulation that develops is strong.

Key Transmission Section Search Based on Graph Theory and PMU Data for Vulnerable Line Identification in Power System

Failure of vulnerable lines in the power system often results in tidal shifts, and triggering chain failures and their corresponding transmission sections are concentrated manifestations of the weak links in the power system. It is very important to identify the vulnerable lines and search the transmission section to prevent the chain faults as well as to analyze the stability of the power system. Aiming at the problems of inaccurate search of vulnerable lines, difficulties adapting to the complex and changing power system as well as wrong selection and omission of transmission section search in the existing references, this paper proposes an algorithm for searching vulnerable lines and their key transmission sections based on the graph theory and PMU (phasor measurement unit) data. First, the method combines with the graph theory and PMU data to construct the grid topology map. Second, the comprehensive indicators for screening vulnerable lines are proposed by fully considering the network topology and line capacity, which combines with power exchange efficiency and energy fluctuation probability. Third, the distance matrix in the Floyd algorithm is transformed into a unit group that can store more elements, which reduces the traversal times of the algorithm and improves computational efficiency. The fast localization of transmission cross sections associated with vulnerable lines is realized. Finally, the critical transmission cross sections are screened according to the line outage distribution factor and line safety margin. The IEEE 39-bus system is selected for simulation experiments, and the simulation results show that the key transmission section search method proposed in this paper can better adapt to the variable power grid and is faster and more accurate than the other common method.