Allometric relationships and trade-offs in 11 common Mediterranean-climate grasses.

Biomass allocation in plants is the foundation for understanding dynamics in ecosystem carbon balance, species competition, and plant-environment interactions. However, existing work on plant allometry has mainly focused on trees, with fewer studies having developed allometric equations for grasses. Grasses with different life histories can vary in their carbon investment by prioritizing the growth of specific organs to survive, outcompete co-occurring plants, and ensure population persistence. Further, because grasses are important fuels for wildfire, the lack of grass allocation data adds uncertainty to process-based models that relate plant physiology to wildfire dynamics. To fill this gap, we conducted a greenhouse experiment with 11 common California grasses varying in photosynthetic pathway and growth form. We measured plant sizes and harvested above- and belowground biomass throughout the life cycle of annual species, while for the establishment stage of perennial grasses to quantify allometric relationships for leaf, stem, and root biomass, as well as plant height and canopy area. We used basal diameter as a reference measure of plant size. Overall, basal diameter is the best predictor for leaf and stem biomass, height, and canopy area. Including height as another predictor can improve model accuracy in predicting leaf and stem biomass and canopy area. Fine root biomass is a function of leaf biomass alone. Species vary in their allometric relationships, with most variation occurring for plant height, canopy area, and stem biomass. We further explored potential trade-offs in biomass allocation across species between leaf and fine root, leaf and stem, and allocation to reproduction. Consistent with our expectation, we found that fast-growing plants allocated a greater fraction to reproduction. Additionally, plant height and specific leaf area negatively influenced the leaf-to-stem ratio. However, contrary to our hypothesis, there were no differences in root-to-leaf ratio between perennial and annual or C4 and C3 plants. Our study provides species-specific and functional-type-specific allometry equations for both above- and belowground organs of 11 common California grass species, enabling nondestructive biomass assessment in California grasslands. These allometric relationships and trade-offs in carbon allocation across species can improve ecosystem model predictions of grassland species interactions and environmental responses through differences in morphology.

How does new energy demonstration city pilot policy affect carbon dioxide emissions? Evidence from a quasi-natural experiment in China.

Energy transition policies are of great significance in adjusting the structure of energy supply and demand and coping with climate change. The new energy demonstration city pilot (NEDCP) policy, as an important pilot project in China's energy transition process, lacks a scientific assessment of the carbon reduction effect of the NEDCP policy and an in-depth explanation of the mechanism of the NEDCP. Based on panel data of 209 Chinese cities at the prefectural and higher levels from 2007 to 2019, this study takes the NEDCP policy as a quasi-natural experiment, using a difference-in-differences model combined with firm-level data to identify the impact of the NEDCP policy on urban carbon dioxide (CO2) emissions. This study analyzes the impact of heterogeneity of urban characteristics on the policy effect from multiple perspectives, and further investigates its mechanism. The conclusions are shown in the following aspects. (1) The implementation of the NEDCP policy decreases urban CO2 emissions significantly. Meanwhile, a series of robustness tests, including the instrumental variables method, propensity score matching difference-in-differences method, placebo test, exclusion of policy interference test, and machine learning method, support this conclusion. (2) The NEDCP policy achieves carbon reduction effects mainly through scale and structure effects. (3) The results of the heterogeneity test show that the NEDCP policy is more effective in cities with higher administrative levels, energy-demanding cities, cities in the southeast of Hu-line, and cities with a higher degree of nationalization. Therefore, the Chinese government should summarize the implementation experience of the NEDCP policy and expand its scope of application. The evaluation of the NEDCP policy in China has important reference value for the energy transition of other developing countries.

The social network perspective on power system co-evolution: responses to "double carbon target" realization in China.

The introduction of dual carbon targets will significantly impact power system development. Despite this, there is currently limited research on achieving system evolution and transition while ensuring safety, low-carbon output, and efficiency, as well as quantitatively analyzing the resulting changes dual carbon targets will have on the power system. Co-evolution of the power system offers a solution to balance the impact of dual carbon goals and enhance interaction among system entities, thereby facilitating the achievement of these goals. Our study focuses on constructing an evolutionary topological network by analyzing the dynamic evolution rule of power systems. We investigate the co-evolution pattern of power systems by analyzing the relationship between the role of power system agents and their dynamic structures. Furthermore, we analyze the future structural changes of power systems, which can provide theoretical support for achieving dual carbon goals in the power system. Our findings highlight key measures to promote synergistic evolution, including increasing energy storage capabilities, stabilizing renewable energy supply, breaking inter-provincial barriers in electricity transmission, and developing a multi-level intelligent power system. Through link analysis, we discover that future power systems will maintain a mild coordination among agents rather than implementing large-scale realignment and reconfiguration. We posit that overcoming obstacles can be achieved by fostering cohesion between the network and agents through technological innovation and widespread market diffusion to drive co-evolution.

A comprehensive city-level final energy consumption dataset including renewable energy for China, 2005-2021.

The role of China is increasingly pivotal in climate change mitigation, and the formulation of energy conservation and emission reduction policies requires city-level information. The effectiveness of national policy implementation is contingent upon the support and involvement of local governments. Accurate data on final energy consumption is vital to formulate and implement city-level energy transitions and energy conservation and emission reduction policies. However, there is a dearth of data sources pertaining to China's city-level final energy consumption. To address these gaps, we developed computational modeling techniques along with top-down and downscaling methods to estimate China's city-level final energy consumption. In this way, we compiled a final energy consumption inventory for 331 Chinese cities from 2005 to 2021, covering seven economic sectors, 30 fossil fuels, and four clean power sources. Moreover, we discussed the validity of the estimation results from multiple perspectives to enhance estimation accuracy. This dataset can be utilized for analysis in various cutting-edge research fields such as energy transition dynamics, transition risk management strategies, and policy formulation processes.

Comparison of diagnostic efficacy of dual-energy CT and ultrasound in gouty arthritis.

OBJECTIVE: To explore the performance and effect of dual-energy computed tomography (CT) and ultrasound in the diagnosis of gouty arthritis and to provide a reference for the clinical diagnosis of gouty arthritis. METHODS: A retrospective analysis of 76 patients with gouty arthritis admitted to the hospital from June 2020 to June 2022 was conducted. Patients were diagnosed with gouty arthritis using ultrasound and dual-energy CT technology. The accuracy of diagnosis by different imaging techniques was analyzed along with the imaging findings of ultrasound and dual-energy CT. RESULTS: Seventy-six patients, 60 men and 16 women, ranging in age from 20 to 77 years (mean age 50.8 ± 10.92 years), presented with uric acid levels of 254.1-720.05 µmol/L (mean 482.17 ± 105.06 µmol/L) and C-reactive protein levels ranging from 4.25 to 10.3 mg/L. The receiver operating characteristic curve showed that the area under the curve and specificity of serum uric acid were higher by dual-energy CT than those of ultrasound in the diagnosis of gouty arthritis. The dual-energy CT detection rate of tophi was significantly higher than the ultrasound detection rate (p < .05). For inflammatory effusion and synovial thickening, the ultrasound detection rates were significantly higher than the dual-energy CT detection rates (p < .05). Regarding soft-tissue edema, the detection rate of the two methods was not significantly different (p > .05). CONCLUSION: Compared with ultrasound, dual-energy CT has increased accuracy in the diagnosis of gouty arthritis.

Succession patterns of aroma components during brewing process of broomcorn millet (Panicum miliaceum L.) Huangjiu.

The flavor of Huangjiu is closely related to its brewing technology. Patterns of aroma component succession during the process of brewing broomcorn millet Huangjiu were investigated by solvent-assisted flavor evaporation combined with gas chromatography-mass spectrometry and chemometrics. During fermentation, esters, alcohols, acids, ketones, acetals, sulfur compounds, furans, and lactones were formed mostly in the chief fermentation stage; nitrogenous and phenolic compounds increased in the primary fermentation stage and then decreased; aldehydes decreased after fermentation started; and terpenes decreased after five days. During aging, acids, alcohols, ketones, lactones, phenols, and nitrogenous and sulfur compounds first decreased and then increased; and esters, acetals, aldehydes, and furans always increased, while terpenes decreased continuously. Key odorants, including acetic acid, 3-methylbutanoic acid, 1,1-diethoxyethane, and 3-methylbutanal, were produced in large quantities in the primary fermentation stage; ethyl lactate, ß-phenylethanol, and 2/3-methyl-1-butanol were generated in large quantities in the chief fermentation stage; and sotolon and methional were generated in the aging stage. This study is of great significance for the quality control of Huangjiu production.

Characterization of key aroma compounds in Huangjiu from northern China by sensory-directed flavor analysis.

Huangjiu (yellow rice wine) from Shanxi province, with a dominant Zao-aroma (fermented grain aroma), is particularly popular in northern China. The key aroma compounds in Huangjiu from Shanxi province were characterized by sensory-directed flavor analysis. A total of 106 compounds separated with solvent-assisted flavor evaporation (SAFE) distillation were identified by gas chromatography-olfactometry (GC-O) coupled with aroma extract dilution analysis (AEDA) and odor specific magnitude estimation (Osme). Forty-seven of them were further quantitated and 21 odorants had odor activity values (OAVs) ≥ 1. The aroma profiles of three recombination models had >95.84% similarities to their corresponding samples. And then, the omission/addition tests further confirmed that ß-phenylethanol, 3-methylbutanoic acid, ethyl lactate, sotolon, 2-acetyl-1-pyrroline, vanillin, ethyl cinnamate, ethyl 3-phenylpropionate, 3-methylbutanal, and methional were the key odorants for Huangjiu from Shanxi province. Meanwhile, it was firstly confirmed that ethyl cinnamate and ethyl 3-phenylpropionate played the key roles in the overall aroma of Huangjiu.