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Background and aims Abandonment of agricultural land is a common type of land-use change worldwide. Nevertheless, there is currently no consensus on how soil aggregates and aggregate-associated organic carbon (C) vary with agricultural land abandonment on a global scale. Methods We synthesized the global responses and controlling factors of distribution, stability, and associated organic C concentration of soil water-stable aggregates under the influence of agricultural land abandonment using meta-analysis. Results On average, agricultural land abandonment significantly enhanced the mass proportion of large macroaggregates (LMA) and mean weight diameter (MWD) by 89.9% and 51.1%, respectively, while leading to a significant reduction in the proportion of silt-clay particles (SC) (−26.6%). By contrast, the proportions of both small macroaggregates (SMA) and microaggregates (MIA) showed no response to agricultural land abandonment. Overall, agricultural land abandonment significantly increased the aggregate-associated organic C concentrations by 23.3–24.8%, and the highest increase was observed for LMA. In most cases, the responses of soil aggregates to agricultural land abandonment did not differ significantly between subgroups of mean annual temperature, mean annual precipitation, soil texture, and abandonment duration (AD). We found that the dynamics of MWD and associated organic C concentrations were positively related to AD according to redundancy analysis. Conclusion Our findings suggested that the formation and C accrual of LMA, which could be improved with the increase of AD due to a more favorable environment for plant and microbial growth, played crucial roles in both soil structural rehabilitation and soil C sequestration during agricultural land abandonment.

This study focuses on the development and implementation of coordinated control and energy management strategies for a photovoltaic–flywheel energy storage system (PV-FESS)-electric vehicle (EV) load microgrid with direct current (DC). A comprehensive PV-FESS microgrid system is constructed, comprising PV power generation, a flywheel energy storage array, and electric vehicle loads. The research delves into the control strategies for each subsystem within the microgrid, investigating both steady-state operations and transitions between different states. A novel energy management strategy, centered on event-driven mode switching, is proposed to ensure the coordinated control and stable operation of the entire system. Based on the simulation results, the PV system cannot cope with the load demand power when it is increased to a maximum of 2800 W, the effectiveness of the individual control strategies, the coordinated control of the subsystems, and the overall energy management approach are confirmed. The main contribution of this research is the development of a coordinated control mechanism that integrates PV generation with FESS and EV loads, ensuring synchronized operation and enhanced stability of the microgrid. This work provides significant insights into optimizing energy distribution and minimizing losses within microgrid systems, thereby advancing the field of energy management in DC microgrids.

The shared energy storage device acts as an energy hub between multiple microgrids to better play the complementary characteristics of the microgrid power cycle. In this paper, the cooperative operation process of shared energy storage participating in multiple island microgrid systems is researched, and the two-stage research on multi-microgrid operation mode and shared energy storage optimization service cost is focused on. In the first stage, the output of each subject is determined with the goal of profit optimization and optimal energy storage capacity, and the modified grey wolf algorithm is used to solve the problem. In the second stage, the income distribution problem is transformed into a negotiation bargaining process. The island microgrid and the shared energy storage are the two sides of the game. Combined with the non-cooperative game theory, the alternating direction multiplier method is used to reduce the shared energy storage service cost. The simulation results show that shared energy storage can optimize the allocation of multi-party resources by flexibly adjusting the control mode, improving the efficiency of resource utilization while improving the consumption of renewable energy, meeting the power demand of all parties, and realizing the sharing of energy storage resources. Simulation results show that compared with the traditional PSO algorithm, the iterative times of the GWO algorithm proposed in this paper are reduced by 35.62%, and the calculation time is shortened by 34.34%. Compared with the common GWO algorithm, the number of iterations is reduced by 18.97%, and the calculation time is shortened by 22.31%.

The degradation of alpine meadows has induced substantial losses of soil organic carbon (SOC) on the Tibetan Plateau. A commonly-used method for rehabilitating degraded alpine meadows in this region is establishing cultivated grasslands through sowing seed mixtures, but its impact on the biochemical stability of SOC has remained inadequately explored. In this study, a total of 20 composited 0-20 cm soil samples were collected from a heavily degraded alpine meadow (DM) and three adjacent cultivated grasslands established for 3 years (CG3), 12 years (CG12), and 17 years (CG17) on the eastern Tibetan Plateau, and the SOC pool was separated into labile C pool I (LOC I), labile C pool II (LOC II), and recalcitrant C pool (ROC) in order to investigate changes in contents of SOC fractions that have different biochemical stabilities after the establishment of cultivated grassland. Although the establishment of cultivated grasslands led to increases in soil total organic C content, the increase was only significant in samples with 17 years of cultivation. We found that the contents of the three SOC fractions were higher at CG3 and CG12 compared with those in the DM, and the differences were only significant for soil LOC II. By comparison, 17 years of cultivation led to significant increases in all of the SOC fraction contents. The results implied that different cultivation years had distinct impacts on SOC fractions in cultivated grasslands, and longer cultivation years contributed to accumulated soil ROC. The recalcitrance index of SOC in the DM was higher than that at CG3 and CG12, but lower than that at CG17. This was possibly due to the generally low litter quality of cultivated grasslands, which led to a slow release of complex compounds to soils. Moreover, it was observed that soil C:N ratio was a potential indicator of SOC biochemical stability because of their close correlation. Our findings suggest that the long-term establishment of cultivated grasslands on DM is a promising solution to recovering both the quantity and stability of SOC on the Tibetan Plateau.

Testosterone (TS) is an important androgen drug and a precursor of steroid drug synthesis. Ketoreductase 2 (KR-2) (GenBank accession no. ABP64403.1) is observed to stereo-selectively catalyze the bioreduction of 4-androstene-3,17-dione (4-AD) to testosterone and contribute to the regeneration of NADH using isopropanol as a co-substrate. The Km value of KR-2 was 2.22 mmol/L with 4-AD, and the optimal pH was 6.5–7.0. The enzyme is stable and demonstrates relatively high-level enzyme activity at 40 °C. Acetone significantly inhibits this activity. This inhibition was overcome using an intermittent vacuum during the reaction process. Finally, the amount of TS reached 65.42 g/L after a 52 h reaction with 65.8 g/L 4-AD, 10% isopropanol, and 2 g/L β–NAD+ at 40 °C, with a conversion rate of 98.73%. A total of 6.15 g of TS was obtained from 6.58 g of 4-AD after the reaction and purification; the HPLC purity was 99.82%, and the overall yield was 92.81%. This enzyme provides a promising route for the green biosynthesis of testosterone for industrial applications.

Active damping methods are widely adopted to present a damping effect on the resonance phenomenon without the power loss of LCL-type converters connected to a grid. However, extra sensors are used to implement the damping strategy. In this paper, a sensorless damping strategy where only the grid current is sampled has been proposed. Furthermore, the inner relationship between the tradition capacitor current feedback strategy and the proposed strategy has been clarified. Considering the digital delay and a weak grid, a robust method that uses unit delay feedback to mitigate the phase lag and to widen the effective damping interval has been developed. With this simple measure, stability is enhanced during the Nyquist frequency and robustness is improved when the LCL parameters vary and grid impedance exists. Finally, simulation and experimental results are presented to verify the feasibility and engineering significance of the proposed strategy.

In this paper, the author combined with gas chromatography to a 1000kV high voltage shunt reactor oil chromatography anomaly analysis, preliminary theoretical analysis conclusion, then in the maintenance process through the equipment breakdown and the fault cause, verify the correctness of the theoretical analysis, for the next step of equipment manufacturers equipment manufacturing and process control provides advice.

( R )-3-Isobutylglutarate monoamide ( R -IBM) is a key intermediate in the synthesis of the analgesic drug pregabalin. Recently, the imidase BpIH derived from Burkholderia phytofirmans was identified as a promising catalyst for the industrial production of R -IBM. Notably, this catalyst has the distinct advantage of achieving a 100% theoretical yield from 3-isobutyl glutarimide (IBI). In this study, homology modeling and structure alignment techniques were used to determine the substrate binding pocket of BpIH. Semi-rational design was used to analyze the amino acid residue conservation in the binding pocket region of BpIH. Interestingly, mutations of several low-conserved amino acid located 6–9 Å from the substrate significantly enhanced the catalytic activity of BpIH. Among them, the triple mutant Y37FH133NS226I (YHS-I) showed approximately a fivefold increase in enzyme activity and a significantly improved catalytic efficiency ( k cat / K m). Under the same reaction time and conditions, YHS-I successfully converted IBI into R -IBM with a conversion rate of 88.87%, with an enantiomeric excess ( ee ) of the product exceeding 99.9%. In comparison, wild-type BpIH had a conversion rate of only 38.15%. Molecular dynamics and docking results indicated that YHS-I had higher rigidity around the mutation sites. The synergistic substitutions of Y37F, H133N, and S226I altered the interaction network within the mutation site, enhancing the protein’s affinity for the substrate and improving catalytic efficiency. Key points • 100% theoretical yield of R-IBM by BpIH compared with 50% by resolution • Semi-rational design of BpIH based on conservativity with homologous enzymes • Mutant with enzyme activity of sixfold and product ee value of 99.9%

Considering the comprehensive demand response, stepwise carbon trading, and uncertainty of wind power output for cogeneration microgrids, relevant optimization scheduling research will be carried out. The electric heating load is divided into non-dispatchable electric heating load and dispatchable electric heating load. By introducing electric heating demand and tiered carbon trading, the economic and low-carbon operation of microgrids can be achieved. The fluctuation of the output of new energy units is reflected using probability scenario sets in statistics, and a robust optimization model with related distributions is constructed using the C&CG algorithm to calculate and solve the established model. The simulation and comparison of numerical examples show that the microgrid energy management scheme formulated by the model established in this paper has good economic and environmental friendliness, and it also simultaneously validated the superiority of distributed robust optimization methods over traditional optimization methods

With the high penetration of renewable energy sources, the reliability of power systems becomes more vulnerable than ever because of the greater uncertainty and intermittence in power generation. Reactive power plays an important role in the power system reliability, because it is closely related to the system voltage stability and voltage collapse. However, reactive power-related reliability issues are seldom emphasized in conventional power reliability evaluations. This article investigates power system reliability of real and reactive power. Real and reactive power shortages and the associated voltage violations due to system failures are considered on reliability evaluation of power systems. A three-stage load-shedding technique for post contingencies is implemented to determine the contributions of real and reactive power on the system reliability and to find an optimal way to release network violation. The results provide the detailed information on power system planning and operation for system planners and operators from real and reactive power aspects.