Increased atmospheric nitrogen (N) deposition has greatly influenced soil organic carbon (SOC) dynamics. Currently, the response of SOC to atmospheric N deposition is generally detected through ...understory N addition, while canopy processes have been largely ignored. In the present study, canopy N addition (CN) and understory N addition (UN, 50 and 100 kg N ha−1 year−1) were performed in a Moso bamboo forest to compare whether CN and UN addition have consistent effects on SOC and SOC turnover times (τsoil: defined as the ratio of SOC stock and soil heterotrophic respiration) with a local NHx:NOy ratio of 2.08:1. The experimental results showed that after five years, the SOC content of canopy water addition without N addition (CN0) was 82.9 g C kg−1, while it was 79.3, 70.7, 79.5 and 74.5 g C kg−1 for CN50, CN100, UN50 and UN100, respectively, and no significant difference was found for the SOC content between CN and UN. Five-year N addition did not significantly change τsoil, which was 34.5 ± 7.4 (mean ± standard error) for CN0, and it was 24.9 ± 4.8, 22.4 ± 4.9, 30.5 ± 4.0 and 22.1 ± 6.5 years for CN0, CN50, CN100, UN50 and UN100, respectively. Partial least squares structural equation modeling explained 93% of the variance in τsoil, and the results showed that soil enzyme activity was the most important positive factor controlling τsoil. These findings contradicted the previous assumption that UN may overestimate the impacts of N deposition on SOC. Our findings were mainly related to the high N deposition background in the study area, the special forest type of Moso bamboo and the short duration of the experiment. Therefore, our study had significant implications for modeling SOC dynamics to N deposition for high N deposition areas.
Nitrogen (N) deposition has been well documented to cause substantial impacts on ecosystem carbon cycling. However, the majority studies of stimulating N deposition by direct N addition to forest ...floor have neglected some key ecological processes in forest canopy (e.g., N retention and absorption) and might not fully represent realistic atmospheric N deposition and its effects on ecosystem carbon cycling. In this study, we stimulated both canopy and understory N deposition (50 and 100 kg N ha−1 year−1) with a local atmospheric NHx:NOy ratio of 2.08:1, aiming to assess whether canopy and understory N deposition had similar effects on soil respiration (RS) and net ecosystem production (NEP) in Moso bamboo forests. Results showed that RS, soil autotrophic (RA), and heterotrophic respiration (RH) were 2971 ± 597, 1472 ± 579, and 1499 ± 56 g CO2 m−2 year−1 for sites without N deposition (CN0), respectively. Canopy and understory N deposition did not significantly affect RS, RA, and RH, and the effects of canopy and understory N deposition on these soil fluxes were similar. NEP was 1940 ± 826 g CO2 m−2 year−1 for CN0, which was a carbon sink, indicating that Moso bamboo forest the potential to play an important role alleviating global climate change. Meanwhile, the effects of canopy and understory N deposition on NEP were similar. These findings did not support the previous predictions postulating that understory N deposition would overestimate the effects of N deposition on carbon cycling. However, due to the limitation of short duration of N deposition, an increase in the duration of N deposition manipulation is urgent and essential to enhance our understanding of the role of canopy processes in ecosystem carbon fluxes in the future.
Background
Soil organic carbon (SOC) is a critical component of the global carbon cycle, and an accurate estimate of regional SOC stock (SOCS) would significantly improve our understanding of SOC ...sequestration and cycles. Zoige Plateau, locating in the northeastern Qinghai-Tibet Plateau, has the largest alpine marsh wetland worldwide and exhibits a high sensitivity to climate fluctuations. Despite an increasing use of optical remote sensing in predicting regional SOCS, optical remote sensing has obvious limitations in the Zoige Plateau due to highly cloudy weather, and knowledge of on the spatial patterns of SOCS is limited. Therefore, in the current study, the spatial distributions of SOCS within 100 cm were predicted using an XGBoost model—a machine learning approach, by integrating Sentinel-1, Sentinel-2 and field observations in the Zoige Plateau.
Results
The results showed that SOC content exhibited vertical distribution patterns within 100 cm, with the highest SOC content in topsoil. The tenfold cross-validation approach showed that XGBoost model satisfactorily predicted the spatial patterns of SOCS with a model efficiency of 0.59 and a root mean standard error of 95.2 Mg ha
−1
. Predicted SOCS showed a distinct spatial heterogeneity in the Zoige Plateau, with an average of 355.7 ± 123.1 Mg ha
−1
within 100 cm and totaled 0.27 × 10
9
Mg carbon.
Conclusions
High SOC content in topsoil highlights the high risks of significant carbon loss from topsoil due to human activities in the Zoige Plateau. Combining Sentinel-1 and Sentinel-2 satisfactorily predicted SOCS using the XGBoost model, which demonstrates the importance of selecting modeling approaches and satellite images to improve efficiency in predicting SOCS distribution at a fine spatial resolution of 10 m. Furthermore, the study emphasizes the potential of radar (Sentinel-1) in developing SOCS mapping, with the newly developed fine-resolution mapping having important applications in land management, ecological restoration, and protection efforts in the Zoige Plateau.
The article uses LabView to develop a fault diagnosis system for wind power planetary transmissions. First, use LabView software to create a signal acquisition system. Then, the built wind turbine ...planetary transmission experiment platform was combined with the NI9171 data acquisition card and the upper computer. The hysteresis brake was used in the laboratory to simulate the external wind environment, and the planetary gear transmission planetary gear crack fault diagnosis and testing experiments were performed. The frequency domain signal is obtained from the initial time domain signal obtained by the experiment through the EMD and envelope demodulation method. The frequency of the corresponding planetary gear crack in the frequency domain signal is compared with the theoretical calculation of the planetary gear crack failure frequency. The results show that the frequency of the corresponding planetary gear cracks in the frequency domain spectra obtained by the experiment is basically consistent with the theoretical calculation of the frequency of cracks in planetary gears. The fault diagnosis system developed by LabView is reliable. The experiment provides a theoretical basis for fault diagnosis, optimisation design, and life prediction of wind turbine planetary transmissions.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
With increasing attention on sustainable development, 3D printing construction and recycled concrete have drawn extensive interest as emerging construction technology and novel building materials. At ...this intersection, we attempted to evaluate the environmental impact and economic benefit of 3D printed buildings made of recycled concrete employing life-cycle assessment tools. Goal and scope definition, materials and scenarios, life-cycle inventory analysis, life-cycle assessment impact, and interpretation were detailed based on the characteristics of concrete 3D printing to better quantify the sustainability potential of recycled concrete used in 3D printed buildings. We found that although increases in using recycled aggregate could produce less pollutant emissions, the environmental impact caused by 3D printing concrete construction is generally larger than traditional cast-in-situ concrete construction. This is because additional cement is required in the 3D printing process to maintain dependable concrete performance. From the economic perspective, 3D printing concrete construction technology has significant advantages over traditional cast-in-situ concrete construction, saving the heavy cost of formwork and labor. Such benefit is even more pronounced in geometrically irregular buildings. We also found that the cost of buildings made of recycled concrete decreased as the proportion of recycled aggregate increased, owing to the higher price of natural aggregate. This paper contributes to identifying key factors in the life-cycle evaluation of 3D printing construction with cementitious materials.
•The sustainability potential of recycled concrete used in 3D printed buildings is evaluated.•3D printed concrete buildings generate higher environmental impact because of additional cement content.•3D printed concrete buildings have significant economic advantages, especially for those geometrically irregular buildings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Microbial conversion of agri-food waste to valuable compounds offers a sustainable route to develop the bioeconomy and contribute to sustainable biorefinery.
displays a series of native traits ...suitable for high productivity conversion of agri-food waste, which make it a promising host for the production of various compounds, such as the short-chain fatty acids and their derivative esters products. In this study, a butanol synthetic pathway was constructed in
, and then efficient butyl butyrate production through in situ esterification was achieved by the supplementation of lipase into the fermentation. The butyryl-CoA/acyl-CoA transferase (
) was overexpressed to balance the ratio between precursors butyrate and butanol. Then, a suitable fermentation medium for butyl butyrate production was obtained with xylose as the sole carbon source and shrimp shell waste as the sole nitrogen source. Ultimately, 5.9 g/L of butyl butyrate with a selectivity of 100%, and a productivity of 0.03 g/L·h was achieved under xylose and shrimp shell waste with batch fermentation in a 5 L bioreactor. Transcriptome analyses exhibited an increase in the expression of genes related to the xylose metabolism, nitrogen metabolism, and amino acid metabolism and transport, which reveal the mechanism for the synergistic utilization of xylose and shrimp shell waste. This study presents a novel approach for utilizing xylose and shrimp shell waste to produce butyl butyrate by using an anaerobic fermentative platform based on
. This innovative fermentation medium could save the cost of nitrogen sources (~97%) and open up possibilities for converting agri-food waste into other high-value products.
As a next‐generation probiotic, Clostridium tyrobutyricum, which is considered obligate anaerobe, has been extensively considered a promising candidate for future use to promote health benefits. The ...industrial applications were limited by its weak tolerance to oxygen stress during fermentation. Here, we enhanced the oxidative stress tolerance of C. tyrobutyricum L319 by deleting the peroxide response regulator gene perR using an endogenous CRISPR‐Cas system. The mutant strain exhibited greatly improved growth when exposed to oxygen, which also showed a shortened lag phase compared with the control strain. Consistently, a concomitant increase in butyric acid productivity from 0.08 to 0.13 g/L/h in the presence of oxygen was observed. Decreased intracellular ROS level sand NAD+/NADH ratios were also observed in the mutant strain. Furthermore, transcriptome and binding target analysis revealed that genes encoding transcriptional regulators and proteins related to redox balance were upregulated. Changes in carbohydrate, amino acid and purine metabolisms upon oxygen exposure were also observed. Importantly, phylogenomic analysis indicated that PerR may be a universal engineering target in diverse Clostridium species. These findings will contribute to the development of robust C. tyrobutyricum strains for efficient butyric acid production in the food industry.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Elevated nitrogen (N) and phosphorus (P) depositions have greatly affected belowground carbon processes in forest ecosystems. However, open questions still remained on the effects of N and P ...depositions on belowground carbon processes, including soil respiration (RS), its source components—autotrophic respiration (RA) and heterotrophic respiration (RH), and total belowground carbon allocation (TBCA) in Moso bamboo forests—one of the most important forest types with wide distributions in subtropical China. To fill this knowledge gap, a two-year N, P, and NP experiment was conducted in Moso bamboo forests. Results showed that RS, RA, and RH had a strong seasonal variability and were exponentially correlated with soil temperature. N and P depositions did not change RS and RA. However, P deposition increased RH due to the stimulation of microbial activities, indicating a significant soil carbon loss under P deposition. N and P depositions did not affect TBCA. However, NP deposition significantly increased root carbon-use efficiency. Net ecosystem production (NEP) varied from 198 ± 104 to 529 ± 225 g C m−2 year−1, indicating that Moso bamboo is an important carbon sink. P deposition marginally decreased NEP, while N and NP depositions did not affect NEP, which indicates that N deposition alleviated the suppression of P deposition on NEP. These findings highlight the inconsistent responses of RA, RH, and NEP to N, P, and NP depositions, which should be differently considered to increase the accuracy of predicting belowground carbon dynamics.
This paper researches Shanghai’s real property registration, studying the data integration of the information database of real property unified registration in Shanghai and the establishment of ...information systems of real property unified registration. The means of data cleaning and data integration are used to consolidate all kinds of basic data for real property which are in complex structure and different formats, building a basic information database for real property and providing a strong support for the establishment of information platform.
This article investigates the feasibility of interconnecting LCC-HVDC and VSC-HVDC through an un-interrupted DC autotransformer (DC AUTO). The interconnected system aims at taking advantage of two ...HVDC technologies. To begin with, the system configuration and the potential benefits are illustrated. Then, the corresponding control strategies towards LCC-HVDC, VSC-HVDC, and the un-interrupted DC AUTO are proposed. The installed controllers enable the system stable operation during both normal time and faulted conditions. Finally, a four-terminal test system is built on PSCAD/EMTDC platform to validate the technical feasibility of the interconnected system and the effectiveness of the proposed control strategy.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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