Average Capacity Research Articles

Techno-Economic Feasibility Study of a Combined Cycle Power Plant Utilizing Natural Gas and Biogas from Cattle Manure Co-firing in South Central Timor

The low electrification ratio in East Nusa Tenggara, particularly in South Central Timor Regency, poses a significant issue. Despite reaching an electrification rate of 92.33%, efforts to achieve 100% are ongoing. South Central Timor as one of the largest cattle farming areas in Indonesia, with its large grasslands and dry climate ideal for cattle farming, has substantial biogas potential from beef cattle manure through anaerobic digestion. Biogas from beef cattle manure has a net calorific value of 18.36 MJ/kg. Based on projections for 2027 using best fit regression, the average daily manure production capacity from 260,217 cattle in South Central Timor is 7.55 kilotons, which is equivalent to approximately 301,852 m3 of biogas. A small-scale combined cycle power plant (CCPP) is proposed to capitalize on this, with a capacity of 20.73 MW and a net thermal efficiency of 55.33%. The plant’s fuel mix will consist of 30% biogas and 70% natural gas by mass, with a fuel mass flow rate of 1 kg/s. The levelized cost of electricity (LCOE), internal rate of return (IRR), and net present value (NPV) obtained from the economic calculations are Rp1,126.76/kWh, 9.62%, and 222 billion IDR with assumptions of a 20-year plant lifetime, an electricity selling price of Rp1,352/kWh, and a discount rate of 6%. The plant is expected to reduce carbon emissions by 61 kilotons annually, while creating new job opportunities in the energy, livestock, and logistics sectors.

Soil Acidification and Its Temporal Changes in Tea Plantations of Guizhou Province, Southwest China

ABSTRACTSoil acidification is a significant problem in intensive agricultural systems, particularly in tea plantations. Guizhou province, located in the center of the karst mountainous region of southwest China, has the largest tea plantation area in China. However, the soil acidification characteristics in the tea plantations of Guizhou province, as well as their temporal changes, have not yet been adequately studied. Therefore, soil acidification and associated soil properties in the major tea‐planting counties of Guizhou province were extensively assessed, and the temporal changes in soil acidity over the past 11 years were also evaluated through long‐term and short‐term experiments. The results showed that the average soil pH in the tea plantations in Guizhou province varied from 4.08 to 4.87, with a mean of 4.47. The average cation exchange capacity (CEC), TEA (total exchangeable acidity, TEA), EH (exchangeable H+), and EA (exchangeable Al3+) values were 9.6, 3.7, 5.8, and 19.0 cmol/kg, respectively. Seasonal changes in tea plantation soil pH were observed in low‐ and moderately acidic soils but not in highly acidic soils. The soil pH values did not significantly change during three consecutive years of in situ observations but significantly decreased over the past 11 years at an average of 0.03 yearly. Correlation analysis revealed that the soil pH in tea plantations was significantly positively correlated with the content of specific amino acids, such as glutamic acid, arginine, and valine, but was significantly negatively correlated with certain soil physicochemical properties. The findings of this study indicate that soil acidification in tea plantations of the Guizhou province is severe and possesses distinctive attributes that should be considered for its effective management.

Dynamic evolution trend and driving mechanisms of water conservation in the Yellow River Basin, China

Water conservation (WC) is a critical ecological service function in the Yellow River Basin (YRB). There is currently a lack of detailed exploration of WC development processes and the impact mechanisms of driving factors at spatiotemporal scales in the YRB. By collecting data on DEM, land use, soil, meteorology, reservoirs, and observed discharge, this study established a large-scale WC model using the soil and water assessment tool (SWAT). The abrupt change test, empirical orthogonal function (EOF), wavelet analysis, hierarchical partitioning analysis (HPA), geodetectors, and aridity index were employed to analyze the multi-spatiotemporal characteristics and driving forces of WC calculated using the water balance method. The results are as follows: (1) The average WC among the YRB was 9.11 mm (74.68 × 108 m3) from 1960 to 2020. Pasture and forests contributed to 48.65% and 22.05% of the average annual WC, respectively. (2) WC exhibited four forms: less/more in the YRB, more in the southeast (northwest), and less in the northwest (southeast). (3) Forests and pastures in land use had higher average WC capacity, while Gansu, Shaanxi, and Qinghai ranked in the top three for average WC among the nine provinces. (4) Precipitation was the major driving force affecting WC variations, with the interaction between precipitation and actual evapotranspiration being the most significant. (5) Drought was a significant cause of negative WC. Protecting and managing crucial WC areas was essential for improving the ecological environment. This research elucidates the driving forces of WC in the YRB, providing scientific support for improving regional WC and promoting sustainable development.

Toward high-integrity forest carbon market of ethnic minority groups in Dak Lak province, Vietnam

Forest carbon markets have demonstrated numerous benefits across economic, social, and environmental dimensions, while also advancing sustainable development goals. This study examines the primary policy mechanisms and conditions related to the development of high-integrity forest carbon markets in Dak Lak province, Vietnam. Utilizing a combination of SWOT analysis and the DPSIR framework, the study provides a comprehensive evaluation of the opportunities, challenges, driving forces, pressures, potential impacts, and responses associated with developing these markets. The Gold Standard method was also employed to estimate the potential contribution to carbon emission reductions through the new forest planting programs in the province. Data analysis from 202 households and in-depth interviews with fifteen experts revealed that local residents have limited information about the forest carbon market. While forest management officials at various levels are aware of the market, there is a lack of specific guidance, limited participation in training sessions and workshops, and insufficient instructional materials. Dak Lak holds significant potential for carbon emission reductions, with an estimated average forest carbon storage capacity of 7.5 tCO2/ha/year for an afforestation/reforestation (A/R) carbon project. This initiative is projected to contribute approximately $753,972 annually to the province’s GRDP and generate 280 jobs for local communities. However, the technical and financial resources are challenging in the province. The study identifies critical issues and proposes appropriate solutions to support Dak Lak in developing high-integrity forest carbon markets in alignment with the national roadmap, ultimately contributing to the achievement of sustainable development goals.

Hybrid FSO/RF and UWOC system for enabling terrestrial-underwater communication: Performance analysis

This work examines the performance of the terrestrial-underwater communication system utilizing hybrid free space optics (FSO)/radio-frequency (RF) and underwater wireless optical communication (UWOC) links. Here, the base station communicates with the underwater vehicle via a decode-and-forward (DF) based relay (buoy) in two phases. In the first phase, a hybrid FSO/RF link is used to transmit signal to the buoy, where the RF link acts as an alternative link to increase the reliability of the system, and in the next phase, the buoy forwards signal to the underwater vehicle through the UWOC link. To enhance the reliability of the RF link, the buoy is deployed with multiple antennas, and it exploits a maximal ratio combining scheme on the received RF signals. The analysis takes into consideration some primary variables that influence the system’s performance, such as atmospheric turbulence, attenuation, temperature gradient, air bubbles, water salinity variations, pointing errors, and detection techniques. Closed-form expressions for the outage probability, system throughput, and average channel capacity in terms of the Meijer-G and bivariate Fox-H functions are derived. Simulation results are presented to validate the analytical expressions and disclose valuable findings.

Fast kinetics for lithium storage rendered by Li3VO4 nanoparticles/porous N-doped carbon nanofibers

Li3VO4 (LVO) has been recognized as an alternative anode material for lithium-ion batteries (LIBs) because of its appropriate lithium storage potential and capacity merits. However, its practical application is seriously hindered by slow reaction kinetics stemming from poor electronic conductivity. Herein, Li3VO4/porous N-doped carbon nanofibers (LVO/PNC NFs) are firstly designed and fabricated via an electrospinning method, utilizing the thermal decomposition characteristics of polylactic acid (PLA). The porous N-doped carbon nanofibers provide efficient electrolyte diffusion paths and facilitate ion transport. In addition, LVO nanoparticles are uniformly dispersed along the nanofibers to effectively inhibit particle aggregation. The obtained LVO/PNC NFs are evaluated as anodes for LIBs and deliver high reversible capacity of 768 mAh g−1 after 300 cycles at 0.2 A g−1, along with excellent rate capability (average capacity of 355 mAh g−1 at 8 A g−1 after 6 periodic rate testing) and long cycling life (286 mAh g−1 after 2000 cycles at 4 A g−1). The special porous nanofiber represents an effective strategy for improving the electronic conductivity, inhibiting particle aggregation, and ensuring rapid ion/charge transport towards advanced energy storage technologies.

Removal of Dibenzofuran from aqueous solution by sugarcane bagasse-based biochar

Dibenzofuran (DBF) has been considered an environmental risk due to its high toxicity and risks to human health and ecosystems. Among wastewater treatment technologies, the adsorption process has emerged as a potential solution to remove organic pollutants efficiently, including dibenzofuran, in wastewater. The study aims to investigate the feasibility of sugarcane bagasse-based biochar for DBF removal through adsorption. Biochar characteristics showed a high specific surface area of up to 498.97 m2/g and abundant functional groups on the material surface, resulting in high removal performance of DBF with average adsorption efficiency and adsorption capacity reaching maximum values of 98.43% and 96.77 mg/g, respectively. The optimum parameters were suggested for DBF removal: pyrolysis temperature of 700oC, contact time of 50 min, biochar dosage of 0.5 g/L, and DBF concentration of 40 mg/L. Furthermore, the results of adsorption kinetics and adsorption isotherms indicated that the adsorption process benefits DBF removal. Pseudo-second-order model and Langmuir model can describe the DBF removal process due to the best fit to experimental data (R2 > 0.98). Based on these findings, sugarcane bagasse-based biochar could be utilized efficiently to remove DBF from wastewater.

Mitigating the Impact of Lognormal Atmospheric Turbulence Channel Estimation on FSO Communication Systems Using Advanced Deep Learning Modules

ABSTRACTCurrently, researchers and commercial entities worldwide are highly interested in optical wireless communication links operating in terrestrial environments. These links offer the distinct advantage of enabling high‐speed data transmission while keeping operational and installation costs low, all without requiring licensing. Free‐space optical (FSO) communication has established itself as a reliable method for delivering ultra‐high data‐rate services. However, the presence of atmospheric turbulence‐induced fading poses a significant challenge for FSO communication systems, particularly when operating over channels affected by time‐varying turbulence. The effectiveness of FSO systems is greatly influenced by atmospheric conditions in a specific area because the laser beam propagates through the atmosphere. As a consequence, this can lead to a significant degradation such as high complexity, high estimation error, and high bit error rate (BER) in the performance of FSO systems. This paper presents a stacked dual attention LSTM network with layered neural Turing machine (SDALSTM‐LaNTM) for FSO channel estimation over lognormal turbulence‐induced fading channels. In this approach, the stacked structure ensures a robust feature extraction capacity of SDALSTM and enhances its ability to capture intricate relationships among multiple atmospheric variables. After employing the stacked LSTM networks, the extracted features are combined with the augmented features obtained through the dual attention (DAttn) mechanism by concatenation. Then the LaNTM architecture used external memory to solve the channel parameter estimation problem and update new set of hidden features for estimation task. The ability to access and update memory enables the model to capture long‐term dependencies and context, making it beneficial for channel prediction in FSO systems. Presently, we are in the process of verifying the channel estimation model using measured FSO channel data. Simulation results clearly demonstrate the outstanding estimation performance of the SDALSTM‐LaNTM model in FSO systems, specifically when dealing with lognormal turbulence‐induced fading channels. Moreover, we highlight the effectiveness of the SDALSTM‐LaNTM model by conducting a comprehensive comparison with existing models, considering factors such as average capacity performance, outage probability estimation, and BER.

Optimized architectural engineering and interface modulation in metallic-phase selenide for exceptional sodium-storage performance

Transition metal selenides (TMSs) exhibit promise as anode materials for sodium-ion batteries (SIBs) due to their high specific capacity and diverse electronic properties. However, practical implementation faces challenges such as structural deterioration, solid-electrolyte interphase (SEI) instability, and diminished coulombic efficiency, especially at the nanoscale. Here, we introduce a novel approach that combines surface engineering of Fe3Se4 with an interface engineering strategy (Fe3Se4@NC) to effectively address these issues. By incorporating engineered void spaces and an electrolyte-blocking layer within micrometer-sized secondary clusters, Fe3Se4 nanoparticles gain the ability to expand and contract freely during cycling, thereby preserving interparticle connections and enhancing the structural integrity. The synergy of surface engineering with a nitrogen-doped carbon layer and interface engineering through electrolyte modulation leads to an outstanding 95.1 % initial Coulombic efficiency in the Fe3Se4@NC electrode. Even after 2000 cycles at 5 A g−1, the electrode retains over 89.2 % of its initial capacity with an average specific capacity of 450 mAh g−1. In situ transmission electron microscopy (TEM) and in situ X-ray diffraction (XRD) analysis shed light on the structural evolution and sodiation dynamics during charge/discharge process. Experimental investigations and DFT calculations provide a comprehensive understanding of the SEI composition and the structural stability of the composite.

Association of left atrial strain and exercise capacity among patients with hypertension: a single center study

Abstract Introduction Hypertension has been identified as one of the leading risk factors for developing cardiovascular disease in the Philippines. 1 The long term increase in afterload causes the progressive decline in both the systolic and diastolic function of hypertensive patients. There has been an increasing recognition in the role of left atrial function in the pathophysiology of several cardiac diseases, including hypertension. Purpose For patients with hypertension, exercise capacity is reduced by 30%.2 As exercise capacity is a known prognostic marker for adverse cardiovascular outcomes, identifying patients with hypertension with impaired left atrial reservoir strain may also improve cardiovascular risk stratification. With the use of two-dimensional (2D) speckle tracking echocardiography, left atrial strain can now be utilized in the evaluation of left atrial reservoir, conduit, and contractile function. Left atrial strain (LA strain) can now serve as a biomarker of adverse cardiovascular outcomes, including the exercise capacity of patients. Another goal of the study is to identify other clinical and echocardiographic factors that may affect exercise capacity Methods A single center, retrospective cross sectional study was conducted in a tertiary hospital to validate the association of left atrial strain with exercise capacity in terms of metabolic equivalent (METs) achieved during treadmill exercise echocardiography of patients diagnosed with hypertension. The primary objective of this study is to determine the left atrial strain cutoff that reliably discriminates poor, fair, average, good, or high exercise capacity. Data was obtained by conducting a chart and echocardiography review of adult patients from January 2023 to April 2023. The independent association of LA strain with METs was studied with regression analysis. Results were considered significant at p≤0.05 at 95% confidence interval. Receiver-operating characteristic curve analysis was utilized to determine the strength of the LA strain to discriminate between the different exercise capacities. Results A total of 136 patients were included in the study. LA strain, particularly the reservoir, can discriminate exercise capacity, specifically to discriminate good to high capacity from fair to average as their AUC is 0.678 (95% CI 0.58 to 0.77, p=.0001). The best cut-off is 30.2 which resulted to 80% sensitivity (95% CI 66.3 to 90) while specificity is only 51.16% (95% CI 40.1 to 62.1). Spearman rank correlation analysis showed that LA reservoir is significantly correlated with E/A and E/e’. The relationships are linear and positive. Among the other 2D echo parameters, only EDV, E/a and E/e’ were found to have a linear relationship or correlation with METS. Conclusion The study revealed that there is moderate correlation of LA reservoir strain in terms of METS achieved during treadmill stress echocardiography (rs=0.3196, p=0.0001).LA reservoir strain AUCLA strain and other echo parameters

Phenolic Content, Antioxidant and Antimicrobial Properties of Hawthorn (Crataegus orientalis) Fruit Extracts Obtained via Carbohydrase-Assisted Extraction

The enzyme-assisted approaches for plant phenolics extraction are more eco-friendly methods compared to acid or alkaline hydrolysis. Carbohydrase enzymes can release free phenolics from plant materials by cleaving the glycosidic bonds between phenolic compounds and cell wall polymers. In this study, the efficiency of carbohydrase-assisted treatment approaches was evaluated to extract bioactive phenolics from hawthorn (Crataegus orientalis) fruit residues. Enzymatic treatment of the fruits was operated by using a crude cellulolytic enzyme cocktail from Rhizomucor miehei NRRL 5282 and a pectinase preparate from Aspergillus niger. Both cellulase and combined cellulase–pectinase treatments improved the total phenolic content (TPC) and antioxidant activity of extracts. The TPC increased to 1899 ± 27 mg gallic acid equivalents/100 g dry matter during the combined enzyme treatment, showing a strong correlation with the average antioxidant capacity determined by ferric-reducing antioxidant power (1.7-fold increment) and 2,2-diphenyl-1-picrylhydrazyl (1.15-fold increment) reagents. The major phenolics in enzyme-treated extracts were vanillic and ferulic acids, the concentrations of which increased 115.6-fold and 93.9-fold, respectively, during carbohydrase treatment. The planktonic growth of Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Chromobacterium violaceum was slightly inhibited by the extracts with minimum inhibitory concentration values between 15.0 and 77.9 mg/mL, while the yeasts tested were quite resistant to the samples. B. subtilis and yeast biofilms were sensitive to the enzyme-treated extracts, which also showed quorum-sensing inhibitory effects against C. violaceum. The obtained bioactive hawthorn extracts hold potential as a natural source of antioxidants and antimicrobials.

Synergistic Interaction of Strongly Polar Zinc Selenide and Highly Conductive Carbon Nanoframeworks Accelerates Redox Kinetics of Polysulfides.

Lithium-sulfur batteries (LSBs) have become strong competitors in secondary battery systems because of their superior theoretical capacity and energy density. However, due to the serious shuttle effect of soluble long-chain lithium polysulfides (LiPSs) and the slow solid-solid reaction kinetics, LSBs face some specific challenges, such as a short cycle life and low rate performance. The introduction of selenide/carbon composites derived from zeolite imidazolate frameworks (ZIFs) into separator coatings is a direct and effective solution to the aforementioned problems. Here, a zinc selenide/carbon catalyst material (ZnSe@C) was constructed and employed to modify commercial polypropylene (PP) separators to accelerate the conversion of intermediates. The highly polar ZnSe effectively fixes the active material on the cathode side by transferring electrons between elements with LiPSs and improves the utilization rate of sulfur. Concurrently, the highly conductive carbon nanoskeleton generated following the pyrolysis of ZIF-8 ensures the rapid transfer of charges during the catalytic reaction. The prepared ZnSe@C has a large specific surface area (250.07 m2 g-1) and mesoporous ratio (78.03%), which not only enhances adsorption and catalysis but also promotes the penetration of the electrolyte and the transport of Li+. Based on this, ZnSe@C/PP separator cells exhibit a low average capacity decay rate of 0.051% per cycle after 500 cycles at 1 C.

Unraveling the paradox of soil erosion and conservation: Insights from China

Analyzing the drivers of soil conservation (SC) service is crucial for ecosystem restoration. However, previous studies often overlook the relationship between soil erosion and SC. In this study, we applied the revised universal soil loss equation (RUSLE) model to analyze the spatiotemporal trends and driving forces of SC service across China from 1990 to 2019. The results indicate that both soil erosion and SC service have exhibited overall increasing trends over the past 30 years. The average SC amount increased 21.3 % from 1990s to 2010s. The average total SC amount and capacity were 229.95 billion t a−1 and 242.91 t ha−1 a−1, respectively. Spatial analysis reveals significant regional variability, with 26.6 % of the land area experiencing fluctuations in SC, these regions contribute to 87.5 % of the total SC amount in the country. We developed a classification system with six patterns to assess the impacts of climate change and human activities on SC. Patterns dominated by climate change exhibit consistent trends in soil erosion and SC service, whereas those dominated by human activities show opposite trends. When climate change and human activities interact, the relationship becomes more complex. Climate change has the most significant influence on SC alterations, affecting 77.1 % of areas with SC changes, while human activities also play a notable role. Although regions primarily impacted by human activities account for only 1.8 % of the total area, they represent 45,200 km2. The remaining 21.1 % of areas are influenced by both climate change and human activities, highlighting the importance of human activities in 22.9 % of areas with SC changes. These findings underscore the synergistic effects of climate change and human activities on SC in China, providing a foundation for future research and the development of targeted SC strategies.

Surface water removal of Aluminum(III), Iron(III) and Manganese(II) using sustainable natural serpentinite mining tailings, proof of concept

To remediate surface water as the Doce River and spring waters from Minas Gerais, Brazil, this study examined the possibility of natural serpentinite mining tailings as a sustainable alternative for removing aluminum (III), iron (III), and manganese (II). The study used a Box-Behnken experimental design to examine how initial metal concentration, adsorbate dosage, and adsorption time affect metal removal effectiveness. Results demonstrated impressive performance, with removal rates exceeding 80 % for Al(III) and Fe(III) within the initial 5 min, and 60 % for Mn(II) within 30 min. This study delves deeper into the removal mechanisms, kinetics, adsorption isotherms and characterization identify physisorption and chemisorption pathways in which complex formation with released OH− groups and ion exchange with Mg(II) from serpentinite emerged as key contributors to the removal process. Furthermore, ion metal adsorption and regeneration cycles were assessed, exhibit sustained removal efficacy without notable capacity reduction. Each cycle shows an average metal adsorption capacity of 0.32 mg g−1 and an average Mg(II) release capacity of 0.98 mg g−1. Remarkably, the application of serpentinite successfully lowered the metals content of the Doce River and spring water to drinkable standards. A batch and continuous process is proposed for scaling-up serpentinite's metal adsorption. Overall, this study shows serpentinite's potential as a foundation for sustainable and cost-effective methods to treat surface water contamination with Al(III), Fe(III), and Mn(II).

Life After Death: Re‐Purposing End‐of‐Life Supercapacitors for Electrochemical Water Desalination

AbstractThis study explores the potential of re‐purposing end‐of‐life commercial supercapacitors as electrochemical desalination cells, aligning with circular economy principles. A commercial 500‐Farad supercapacitor was disassembled, and its carbon electrodes underwent various degrees of modification. The most straightforward modification involved NaOH‐etching of the aluminum current collector to produce free‐standing carbon films. More advanced modifications included CO2 activation and binder‐added wet processing of the electrodes. When evaluated as electrodes for electrochemical desalination via capacitive deionization of low‐salinity (20 mM) NaCl solutions, the minimally modified NaOH‐etched carbon electrodes achieved an average desalination capacity of 5.8 mg g−1 and a charge efficiency of 80 %. In contrast, the CO2‐activated, wet‐processed electrodes demonstrated an improved desalination capacity of 7.9 mg g−1 and a charge efficiency above 90 % with stable performance over 20 cycles. These findings highlight the feasibility and effectiveness of recycling supercapacitors for sustainable water desalination applications, offering a promising avenue for resource recovery and re‐purposing in pursuing environmental sustainability.

Surface modification of cotton fabric by kaolin-derived zeolite N to enhance efficient removal of particulate matter

Reducing the amount of fine particulate matter (PM) in the atmosphere is essential for preserving a secure and healthy environment. Here, we synthesized zeolite N (potassium ion form, KN) from kaolin clay minerals, coated it on cotton fabric using a simple refluxing method and then removed PM from the air. The following conclusion can be drawn. The average cation exchange capacity (CEC) of KN was 512 meq/100 g, and a CEC value > 400 meq/100 g indicated pure zeolite with a Si/Al ratio of approximately 1.0. The synthesized KN, containing a high proportion of Al, proved highly effective in removing particulates. For instance, KN/cotton (746 GSM (weight of fabric in g/m2) cotton, coated with approximately 1.46 wt% KN) demonstrated an 8-times higher removal efficiency (RE) for PM2.5 and PM1.0 than bare 746 GSM cotton, with only a 7 Pa increase in the pressure drop. PM may have been removed by electrostatic interactions between the charged PM and KN (with charge-balancing cations) owing to the charges and polarity of the outer layer of PM particles. According to the increases in RE and the quality factor, KN/cotton (746 GSM) was the most effective in removing PM from the air compared to other materials. The results suggested that KN, when applied to the surface of cotton fabric, is highly efficient due to its EDI framework structure and high Al content. Finally, biodegradation tests revealed that used filters disintegrated into pieces after being buried for one month in soil, indicating their environmental friendliness.

Controllable assembly of polysulfides mediator induced by host-guest chemistry for upgrading energy density and longevity of lithium-sulfur batteries

Rechargeable lithium-sulfur (Li-S) batteries are deemed to one potential candidate for next-generation energy storage systems due to high theoretical energy density and environmental friendliness of sulfur. However, the sluggish redox kinetics and the inevitable shuttle effect of soluble polysulfides impede their commercialization process. Herein, the host–guest chemistry strategy has been proposed to fabricate ultrafine Co9S8/CoO nanoparticles embedded in porous carbon nanosheets (Co9S8/CoO@PC) for improving reversible conversion kinetics and adsorption ability toward polysulfides. Benefiting from bidirectional catalysis of Co9S8/CoO heterostructure and the fully exposed active sites on porous carbon nanosheets, the resultant Co9S8/CoO@PC-S electrode exhibits high specific capacity of 1549 mA h/g at 0.1C as well as outstanding cyclic stability with low average capacity decay of 0.021 % in 1000 cycles at high rate of 3C. Remarkably, the electrode delivers high specific capacities of 1209 and 756 mA h/g at 0.1C after 100 cycles with high sulfur loadings of 4.0 and 7.5 mg cm−2, respectively. This work provides new methodology for the controllable assembly of multiple dimensional composites to realize high energy density and long lifetime of Li-S batteries.

Estimating Grassland Carrying Capacity in the Source Area of Nujiang River and Selinco Lake, Tibetan Plateau (2001–2020) Based on Multisource Remote Sensing

Estimating the spatiotemporal variations in natural grassland carrying capacity is crucial for maintaining the balance between grasslands and livestock. However, accurately assessing this capacity presents significant challenges due to the high costs of biomass measurement and the impact of human activities. In this study, we propose a novel method to estimate grassland carrying capacity based on potential net primary productivity (NPP), applied to the source area of the Nujiang River and Selinco Lake on the Tibetan Plateau. Initially, we utilize multisource remote sensing data—including soil, topography, and climate information—and employ the random forest regression algorithm to model potential NPP in areas where grazing is banned. The construction of the random forest model involves rigorous feature selection and hyperparameter optimization, enhancing the model’s accuracy. Next, we apply this trained model to areas with grazing, ensuring a more accurate estimation of grassland carrying capacity. Finally, we analyze the spatiotemporal variations in grassland carrying capacity. The main results showed that the model achieved a high level of precision, with a root mean square error (RMSE) of 4.89, indicating reliable predictions of grassland carrying capacity. From 2001 to 2020, the average carrying capacity was estimated at 9.44 SU/km2, demonstrating a spatial distribution that decreases from southeast to northwest. A slight overall increase in carrying capacity was observed, with 65.7% of the area exhibiting an increasing trend, suggesting that climate change has a modest positive effect on the recovery of grassland carrying capacity. Most of the grassland carrying capacity is found in areas below 5000 m in altitude, with alpine meadows and alpine meadow steppes below 4750 m being particularly suitable for grazing. Given that the overall grassland carrying capacity remains low, it is crucial to strictly control local grazing intensity to mitigate the adverse impacts of human activities. This study provides a solid scientific foundation for developing targeted grassland management and protection policies.

Crack propagation behavior and failure prediction of rocks with non-parallel conjugate flaws: Insights from the perspective of acoustic emission and DIC

Rock-like containing non-parallel conjugate flaws specimens (NPCFS) were prepared and uniaxial compression crack propagation tests were conducted employing acoustic emission (AE) and digital image correlation (DIC) techniques. The results show that: the angle of conjugate unilateral cracks increases, the average load-bearing capacity of the rock rises. Dominant frequencies from different conjugate defect angles exhibit distinct bimodal characteristics (low-frequency: 80–140 kHz, intermediate-frequency: 260–320 kHz). The concept of AE dominant frequency ratio β is proposed and introduced to quantify the strength of macro-scale failure of the specimens. The AE multiparameter is proposed to predict the failure load, and the mean value of failure load is predicted to be in the range of 86–93 % (failure load), the prediction interval of Ib value is in the range of 95–99 %, the prediction interval of critical slowing down variance value is in the range of 90–95 %, while the prediction interval of autocorrelation coefficient is in the range of 83–90 %. A favorable correlation was observed between AE events in NPCFS and surface deformations observed through DIC technology. Both ends of the conjugate flaw cannot propagate simultaneously; once one extends, the other ceases further expansion, forming a primary failure line that propagates towards the direction of the primary compressive stress.

Electrolyte-triggered in-situ polymerization of multi-site organic cathodes for superior-longevity cation-anion co-storage secondary batteries

Organic electrodes are promising as next-generation energy storage materials owing to their diverse structures, low mass, and environmental friendliness. Nevertheless, the dissolution and degradation of organic active species in electrolytes are remaining obstacles to their authentic commercialization. Herein, we report an instantaneous in-situ upgrading strategy to convert multi-site organic cathode materials, e.g., 1-aminoanthraquinone (1-AAQ) and 1,5-diaminoanthraquinone (1,5-DAAQ), into poly(1-aminoanthraquinone) (PAAQ) and poly(1,5-diaminoanthraquinone) (PDAAQ) simply by dropping the electrolyte during battery assembly without extra operations. The remarkable chemistry is essentially a chemical polymerization process of redox-active organic monomers triggered by the electrolyte containing magnesium bis(hexamethyldisilazide) (Mg(HMDS)2) as an initiator. Notably, due to the π-conjugated polymer chain with inhibited dissolution, high conductivity, and improved stability, the as-obtained PDAAQ cathode delivered a high specific capacity (254 mAh/g at 100 mA/g), superior rate performance (83 mAh/g at 2000 mA/g), and excellent cycling stability for over 8000 cycles accompanied by an average capacity decay of only 0.0026 % per cycle. Detailed characterizations further explore the kinetic behaviors and verify a reversible hybrid cation–anion co-redox mechanism of PDDAQ cathode, which involves reversible Mg2+ cation insertion/extraction on AQ units and anion doping/de-doping reactions on the PANI backbones. Density functional theory (DFT) computations demonstrate the optimized structure of the discharged products and indicate that Mg2+ preferably interact with two carbonyls oxygen atoms and nitrogen atom for both PAAQ and PDAAQ. This study demonstrates an intriguing in-situ chemical-polymerization synthetic approach for preparing multi-site organic electrode materials that compromise structure optimization and synthetic efforts, offering great promise for high-performance and sustainable secondary batteries.