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CQDs/ZnIn2S4 (CQDs represents carbon quantum dots) nanocomposites were prepared via a microwave-assisted hydrothermal method. The photocatalytic activity for the reduction of Cr(VI) to Cr(III) over the as-prepared CQDs/ZnIn2S4 nanocomposites under visible light irradiations was studied. The study found that the reduction of Cr(VI) to Cr(III) over hexagonal ZnIn2S4 can be significantly increased by loading CQDs as a co-catalyst. After 60 min of visible light illumination (λ > 420 nm), almost 100% Cr(VI) can convert to Cr(III) with (NH4)2C2O4 as a scavenger. Furthermore, the CQDs/ZnIn2S4 nanocomposites are demonstrated to execute as bifunctional photocatalysts with appreciable activity in the hybrid systems (Cr(VI)/RhB) under visible light, which made it a potential application material for industrial wastewater treatment. Combined with photoelectrochemical analyses, it can be found that the introduction of CQDs can reduce the recombination of photogenerated electron-hole pairs. Finally, a possible photocatalytic reaction mechanism is also proposed. [ABSTRACT FROM AUTHOR]

Infrared photodissociation spectra of the D2-tagged microhydrated sulfate dianions with three to eight water molecules are presented over a broad spectral range that covers the OH stretching and H2O bending modes of the solvent molecules at higher energies, the sulfate stretching modes of the solute at intermediate energies and the intermolecular solute librational modes at the lowest energies. A low ion temperature combined with messenger-tagging ensures well-resolved vibrational spectra that allow for structure assignments based on a comparison to harmonic and anharmonic IR spectra from density functional theory (DFT) calculations. DFT ab initio molecular dynamics simulations are required to disentangle the broad and complex spectral signatures of microhydrated sulfate dianions in the OH stretching region and to identify systematic trends in the correlation of the strength and evolution of the solute–solvent and solvent–solvent interactions with cluster size. The onset for the formation of the second solvation shell is observed for n = 8. [ABSTRACT FROM AUTHOR]

For the oxygen reduction reaction (ORR) in acidic media, a proton is a key component in the hydrogenation of O2, O, and OH. Modeling a proton requires an explicit account of its solvation and its dynamic nature in the interfacial solution region. We employed ab initio molecular dynamics to study these reactions on Pt(111), which is a model problem in electro-catalysis. Our results show that the branching ratio for the two hydrogenation channels of O atoms adsorbed on Pt(111) shifts dramatically with the electrode potential. This kinetic factor underlies the electrochemical observations peculiar to ORR on Pt(111) and provides an explanation for the long-standing puzzle of its high onset overpotential. [ABSTRACT FROM AUTHOR]

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The red Pisha sandstone was taken as absorbents to investigate the effects of the solution pH, the adsorption time and temperature adsorption onto Ni (II) absorption by the Pisha sandstone, and used dynamics and thermodynamic absorption models, coupled with microcalorimetry and infrared spectroscopic (FTIR) analysis, and scanning electron microscope-energy dispersive spectrometer (SEM-EDS); it aimed to determine the mechanism of thermodynamics and kinetics for Pisha sandstone absorbing Ni (II). The results indicated that the adsorption was performed at 293 K, pH 7, and the equilibrium was reached at 30 min, and the adsorption capacity of Ni (II) was 23.688 mg/g; the adsorption process of Ni (II) onto Pisha sandstone could be described with the Lagrangian pseudo-second-order kinetic model, the Freundlich model, and Dubinin-Radushkevich (D-R) model which all could well simulate the isothermal properties, indicating that the adsorption process was mainly monolayer with heterogeneous surface. According to the microthermal process and thermodynamic analysis, the thermodynamic parameters of Gibbs free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS) were less than zero, showing that the adsorption of Ni (II) onto Pisha sandstone was exothermic, spontaneous, and entropy increasing. The absorptive models, FTIR analysis, and SEM-EDS demonstrated that the Pisha sandstones absorbing Ni (II) were mainly ion exchange and chemical adsorption meanwhile chemical precipitation little partly worked in the processes. [ABSTRACT FROM AUTHOR]

Alkali metal ammonia clusters, in their cationic, neutral, and anionic form, are molecular models for the alkali-ammonia solutions, which have rich variation of phases with the solvated electrons playing an important role. With two s electrons, the Na-(NH3)n and Li-(NH3)n clusters are unique in that they capture the important aspect of the coupling between two solvated electrons. By first principles calculations, we demonstrate that the two electrons are detached from the metal by n = 10, which produces a cluster with a solvated electron pair in the vicinity of a solvated alkali cation. The coupling of the two electrons leads to either the singlet or triplet state, both of which are stable. They are also quite distinct from the hydrated anionic clusters Na-(H2O)n and Li-(H2O)n, in that the solvated electrons are delocalized and widely distributed among the solvent ammonia molecules. The Na-(NH3)n and Li-(NH3)n series, therefore, provide another interesting type of molecular model for the investigation of solvated electron pairs. [ABSTRACT FROM AUTHOR]

By first principles calculations, we explore the possibility that Na-(H2O)n and Li-(H2O)n clusters, which have been measured previously by photoelectron experiments, could serve as gas-phase molecular models for the solvation of two electrons. Such models would capture the electron-electron interaction in a solution environment, which is missed in the well-known anionic water clusters (H2O)n-. Our results show that by n = 10, the two loosely bound s electrons in Li-(H2O)n are indeed detached from lithium, and they could exist in either the singlet (spin-paring) or the triplet (spin-coupling) state. In contrast, the two electrons would prefer to stay on the sodium atom in Na-(H2O)n and on the surface of the cluster. The formation of a solvated electron pair and the variation in solvation structures make these two cluster series interesting subjects for further experimental investigation. [ABSTRACT FROM AUTHOR]

During homogenous catalysis by organometallic complexes, the dissociation of a ligand to produce an unsaturated site on the metal center is often invoked as the first step of activation, especially when photo-excitation is involved. In this theoretical study, we demonstrated that under mild conditions, a thermodynamically unstable yet dynamically favorable active intermediate could be produced by the inhomogeneity of the solvent distribution around the catalyst rather than by ligand dissociation. This occurred at the end of the first catalytic cycle when the product was eliminated. The empty site was immediately filled by one of the additive molecules aggregated around the reaction center even when the intermediate complex was unstable, producing a transient and more active catalyst. This process accounted for the accelerated reaction rate observed in the landmark CO2 hydrogenation catalyzed by (PMe3)4RuH2 in supercritical CO2 when H2O, MeOH, or HNMe2 was added. This also suggests a new way to exploit the structural inhomogeneity around an organometallic complex for the design of superior catalysts. [ABSTRACT FROM AUTHOR]

Cardiovascular dysfunction is a common complication among heatstroke patients, but its underlying mechanism is unclear. This study was designed to investigate the role of calpain‐2 and its downstream signal pathway in heat stress‐induced cardiomyocyte apoptosis and heart dysfunction. In cultured primary mouse neonatal cardiomyocytes (MNCs), heat stress (43°C for 2 hr) induced a heat‐shock response, as indicated by upregulated heat‐shock protein 27 (HSP27) expression and cellular apoptosis, as indicated by increased caspase‐3 activity, DNA fragmentation and decreased cell viability. Meanwhile, heat stress decreased calpain activity, which was accompanied by downregulated calpain‐2 expression and increased phosphorylation of p38, extraceIIuIar signaI‐reguIated protein kinase (ERK1/2) and c‐Jun N‐terminaI kinase (JNK). Calpain‐2 overexpression abrogated heat stress‐induced apoptosis and phosphorylation of p38 and JNK, but not of ERK1/2. Blocking only p38 prevented heat stress‐induced apoptosis in MNCs. In cardiac‐specific calpain‐2 overexpressing transgenic mice, p38 phosphorylation and cardiomyocyte apoptosis were decreased in the heart tissue of heatstroke mice, as revealed by western blot and terminal deoxynucleotidyl transferase dUTP nick end labelling assays, respectively. M‐mode echocardiography also demonstrated that calpain‐2 overexpression significantly improved heatstroke‐induced decreases in ventricular end‐diastolic volume and cardiac output. In conclusion, our study suggests that heat stress reduces calpain‐2 expression, which then activates p38, leading to cardiomyocyte apoptosis and heart dysfunction. Heat stress could induce cardiomyocyte apoptosis and decrease calpain‐2 expression and total calpain activity, and increase phosphorylation of p38, extracellular signaI‐reguIated protein kinase (ERK1/2) and c‐Jun N‐terminaI kinase (JNK). Calpain‐2 overexpression could abrogate heat stress‐induced phosphorylation of p38 but not ERK1/2 and JNK, thereby decrease cardiomyocyte apoptosis and heart dysfunction. Targeting calpain‐2 may be a potential therapeutic strategy for heatstroke‐induced myocardial complications.. [ABSTRACT FROM AUTHOR]

The fatty acid accumulation in broodstock influences the fecundity of spawners as well as egg quality. A comprehensive understanding of the lipid and fatty acid changes in broodstock during the reproductive period can increase our knowledge of the nutritional requirements in artificial breeding programs. The study assessed the lipid and fatty acid compositions of muscle, liver and ovary of American shad at different stages of reproductive development under reared conditions. The results indicated that there were significant differences in lipid content among ovary, liver and muscle. Mean total lipid levels in ovary, liver and muscle were 15.92%–10.87%, 13.62%–6.89%, 10.39%–6.11% respectively. During the development season, the total lipid content in muscle in stages V and VI were significantly lower than those in stages II and III. The total lipid content in liver in stages IV, V and VI was significantly lower than in stages II and III, whereas the total lipid content in the ovary increased significantly as the gonad developed and reached its highest value at stage V. From II to VI stage, the liver content of docosahexaenoic acid (DHA) decreased and the ovarian content of DHA increased, whereas the content of eicosapentaenoic acid (EPA) remained relatively constant. The content of C16:0 and C18:1n‐9 decreased in muscle and liver, but significantly increased in ovary. It is therefore suggested that the lipids were preferentially transferred from muscle and liver to ovary beginning in stage IV as the gonad matured. At stage IV, the lipid transfer accelerated, and saturated and unsaturated fatty acids, such as C16:0, C18:1n‐9, DHA, EPA and arachidonic acid, were selectively transferred to and conserved in ovaries. [ABSTRACT FROM AUTHOR]

Abstract This study contributes to proposing the improved bird swarm algorithm optimization least squares support vector machine (IBSA-LSSVM) model to predict the remaining life of lithium-ion batteries. By improving the prediction accuracy of the model, the safety and reliability of the new energy storage system are improved. In order to avoid the bird swarm algorithm (BSA) getting into the local optimal solution, the levy flight strategy is introduced into the improved bird swarm algorithm (IBSA), which improves the convergence performance of the algorithm. Hence, this study is to verify the effectiveness of the proposed hybrid IBSA-LSSVM model. The following work has been done: (1) test functions are used to test particle swarm optimization (PSO), differential evolution algorithm (DE), BSA and IBSA; (2) the back propagation neural network (BP) model, support vector machine (SVM) model, quantum particle swarm optimization support vector machine (QPSO-SVM) model, BSA-LSSVM model and IBSA-LSSVM model are tested with the B5, B6 and B18 batteries. The following findings are obtained: (1) the five test functions are used to test the PSO, DE, BSA and IBSA algorithms in 20 dimensions, 50 dimensions and 80 dimensions. The results show that the convergence accuracy and convergence stability of IBSA algorithm is higher than those of the other three algorithms; (2) the residual life of B5, B6 and B18 batteries are predicted by the BSA-LSSVM, SVM, QPSO-SVM, BP and IBSA-LSSVM models. The test results show that the root mean square error of the IBSA-LSSVM model for B5 battery is 0.01, the root mean square error for B6 battery is 0.06, and the root mean square error for B18 battery is 0.02. The results show that the prediction accuracy of proposed model is higher than that of the other models. Highlights • The proposed IBSA-LSSVM model is proposed to predict the lifetime of Lithium-ion batteries. • The proposed model is to optimize the penalty coefficient and kernel width. • The results indicated the prediction accuracy of IBSA-LSSVM model is higher. [ABSTRACT FROM AUTHOR]

A time-delay chaotification approach can be applied to the Chua's circuit by adding a small-amplitude time-delay feedback voltage to the circuit. The chaotic dynamics of this newly derived time-delay Chua's circuit is studied by theoretical analysis, verified by computer simulations as well as by circuit experiments. Index Terms--Chaos, stability, time delay.

New energy power generation plays an important role in adjusting energy structure, reducing environmental pollution, and promoting sustainable social development. However, new energy power generation represented by solar and wind power has significant volatility, meanwhile, the wind and solar curtailment caused by uncertainty reduce utilization rate. In this context, considering the impact of uncertainty in new energy generation on system scheduling and developing new algorithms that can efficiently solves such complex scheduling problems are necessary. Therefore, this study constructed a hybrid dynamic economic emission model (HDEED) with the new energy generation penalty mechanism, and proposed a novel multi-objective tunicate swarm algorithm (MTSA)-based solution method. First, based on the unit operation characteristic equations, considering wind and solar power uncertainty, the HDEED model with the new energy generation penalty mechanism was constructed. Second, on the basis of the single objective tunicate swarm algorithm, MTSA algorithm was proposed by adding the running operators, and the feasibility of the proposed algorithm was verified. The test results showed that the Pareto fronts obtained by MTSA algorithm presented good distribution and diversity compared with existing algorithms. Finally, the proposed model and algorithm were proved by modified test system, meanwhile, the impacts of clean energy power on system operation stability, economic and environmental benefits were discussed. The results revealed that the penalty costs caused by uncertainty were higher than the operation and maintenance costs of new energy power stations, which accounted for about 2.1% of the total costs. The outcomes obtained in this study contribute to improving the utilization rate of clean energy and promoting the sustainable development of energy system. • Considering clean energy power uncertainty, the HDEED model is constructed. • A novel MTSA-based solution method with strong convergence performance is proposed. • The obtained outcomes contribute to improving the utilization rate of clean energy. [ABSTRACT FROM AUTHOR]

As a crucial aspect of pollution emissions, the transformation and upgrading of the power industry urgently require attention. Utilizing renewable energy generation techniques is an effective means to promote energy conservation and emission reduction within the power industry. However, the utilization rates of renewable energy generation are hindered by significant randomness and uncertainty associated with renewable energy power. In light of these challenges, this study constructed a hybrid economic emission dispatch (HDEED) model to explore the establishment of effective regulation mechanism under renewable energy grid connection. First, taking into account dynamic constraints, the wind-solar-thermal-storage HDEED model was constructed with operation costs and pollution emissions as objective functions. Second, an optimal dynamic grid connection factor strategy and the GWOH-based solution method were proposed. Finally, the proposed strategy and algorithm were verified using an improved IEEE-39 bus test system. The results revealed that under the same test conditions, the Pareto optimal frontiers obtained by the GWOH algorithm demonstrated the most competitive performance. Furthermore, the system cost achieved by GWOH was 4.52% lower than that without renewable energy access, while emissions were reduced by 11.84% under the optimal dynamic factor grid connection strategy. This study significantly contributes to the improvement of energy management efficiency and the enhancement of renewable energy utilization rates in the power industry. [ABSTRACT FROM AUTHOR]