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Ecological stoichiometry connects different levels of biology, from the gene to the globe, by scaling up elemental ratios (e.g. carbon [C], nitrogen [N] and phosphorus [P]). Thus, ecological stoichiometry could be a powerful tool for revealing certain physiological processes of plants. However, C:N:P stoichiometry remains unclear at the community and ecosystem levels, despite it being potentially important for primary productivity. In this study, we measured the C, N and P contents of different plant organs, litter and soil in nine natural forest ecosystems (from cold‐temperate to tropical forests along a 3,700‐km transect in China) to explore C:N:P stoichiometry and the main influencing factors. C:N:P stoichiometry was evaluated for different components in the forest ecosystems (plant community, soil, litter and ecosystem) and, at the community level, for different organs (leaves, branches, trunks and roots) from 803 plant species. The ratios of C:P and N:P decreased with increasing latitude, with spatial patterns being primarily regulated by climate. Interestingly, the homeostasis of N, P and N:P was highest in leaves, followed by branches, roots and trunks, supporting the hypothesis that more active organs have a higher capacity to maintain relatively stable element content and ratios. At the community level, the leaf N:P ratio indicated increasing P limitation in forests of lower latitude (i.e. more southerly) in China's forests. Our findings demonstrate the spatial patterns of C:N:P stoichiometry and the strategies of element distribution among different organs in a plant community, providing important data on C:N:P to improve the parameterization of future ecological models. A plain language summary is available for this article. Plain Language Summary

The occurrence of hypoxia in coastal oceans is a long-standing and growing problem worldwide and is clearly linked to anthropogenic nutrient inputs. While the need for reducing anthropogenic nutrient loads is generally accepted, it is costly and thus requires scientifically sound nutrient-reduction strategies. Issues under debate include the relative importance of nitrogen (N) and phosphorus (P) as well as the magnitude of the reduction requirements. The largest anthropogenically induced hypoxic area in North American coastal waters (of 15 000 ± 5000 km2) forms every summer in the northern Gulf of Mexico where the Mississippi and Atchafalaya rivers deliver large amounts of freshwater and nutrients to the shelf. A 2001 plan for reducing this hypoxic area by nutrient management in the watershed called for a reduction of N loads. Since then evidence of P limitation during the time of hypoxia formation has arisen, and a dual nutrient-reduction strategy for this system has been endorsed. Here we report the first systematic analysis of the effects of single and dual nutrient load reductions from a spatially explicit physical–biogeochemical model for the northern Gulf of Mexico. The model has been shown previously to skillfully represent the processes important for hypoxic formation. Our analysis of an ensemble of simulations with stepwise reductions in N, P, and N and P loads provides insight into the effects of both nutrients on primary production and hypoxia, and it allows us to estimate what nutrient reductions would be required for single and dual nutrient-reduction strategies to reach the hypoxia target. Our results show that, despite temporary P limitation, N is the ultimate limiting nutrient for primary production in this system. Nevertheless, a reduction in P load would reduce hypoxia because primary production is P limited in the region where density stratification is conducive to hypoxia development, but reductions in N load have a bigger effect. Our simulations show that, at present loads, the system is almost saturated with N, in the sense that the sensitivity of primary production and hypoxia to N load is much lower than it would be at lower N loads. We estimate that reductions of 63±18 % in total N load or 48±21 % in total N and P load are necessary to reach a hypoxic area of 5000 km2, which is consistent with previous estimates from statistical regression models and highly simplified mechanistic models.

Drought is a key limiting factor for cotton (Gossypium spp.) production, as more than half of the global cotton supply is grown in regions with high water shortage. However, the underlying mechanism of the response of cotton to drought stress remains elusive. By combining genome-wide transcriptome profiling and a loss-of-function screen using virus-induced gene silencing, we identified Gossypium hirsutum GhWRKY59 as an important transcription factor that regulates the drought stress response in cotton. Biochemical and genetic analyses revealed a drought stress-activated mitogen-activated protein (MAP) kinase cascade consisting of GhMAP3K15–Mitogen-activated Protein Kinase Kinase 4 (GhMKK4)–Mitogen-activated Protein Kinase 6 (GhMPK6) that directly phosphorylates GhWRKY59 at residue serine 221. Interestingly, GhWRKY59 is required for dehydration-induced expression of GhMAPK3K15, constituting a positive feedback loop of GhWRKY59-regulated MAP kinase activation in response to drought stress. Moreover, GhWRKY59 directly binds to the W-boxes of DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN 2 (GhDREB2), which encodes a dehydration-inducible transcription factor regulating the plant hormone abscisic acid (ABA)-independent drought response. Our study identified a complete MAP kinase cascade that phosphorylates and activates a key WRKY transcription factor, and elucidated a regulatory module, consisting of GhMAP3K15-GhMKK4-GhMPK6-GhWRKY59-GhDREB2, that is involved in controlling the cotton drought response.

This paper presents a new method of reducing the inrush current and improving the starting performance of a line-start permanent-magnet synchronous motor (LSPMSM). The novelty of the proposed method relies on the selection of the time instant of the connection of the stator winding to the grid, for which the smallest values of the amplitudes of inrush currents are obtained. To confirm the effectiveness of the developed method of limiting the inrush current, simulations and experimental studies were carried out. The algorithm and dedicated computer code developed by the authors for the analysis of transient coupled phenomena in the LSPMSM were used to study the impact of the time instant of connection of the winding to the grid on the motor start-up process. The algorithm was based on a field model of coupled electromagnetic and thermal phenomena in the studied motor. To verify the developed model of the phenomena and the proposed method, experimental research was carried out on a purpose-built computerised test stand. Good concordance between the results of the experiments and simulations confirmed the high reliability of the proposed model, as well as the effectiveness of the developed approach in limiting the inrush current and improving the starting performance of LSPMSMs.

Precise finite element modeling is critically important for the construction and maintenance of long-span suspension bridges. During the process of modeling, shape-finding and model calibration directly impact the accuracy and reliability. Scholars have provided numerous alternative proposals for the shape-finding of main cables in suspension bridges from both theoretical and finite element analysis perspectives. However, it is difficult to apply these solutions to suspension bridges with special components. Seeking a viable solution for such suspension bridges holds practical significance. The Nanjing Qixiashan Yangtze River Bridge is the first three-span suspension bridge in China. To maintain the configuration of the main cable, the suspension bridge is equipped with specialized suspenders near the anchors, referred to as displacement-limiting suspenders. It is the first suspension bridge in China to use displacement-limiting suspenders and their anchorage system. Taking the suspension bridge as a research background, this paper introduces a refined finite element modeling approach considering the effect of geometric nonlinearity. Firstly, based on the loop adjustment and temperature correction, the shape-finding and force assessment of the main cables are carried out. On this basis, a nonlinear finite element model of the bridge was established and calibrated, taking into account factors such as pylon settlement and cable saddle precession. Finally, the static and dynamic characteristics of the suspension bridge were thoroughly investigated. This study aims to provide a reference for the design, construction and operation of the three-span continuous suspension bridge.

The North Pacific is known with iron limitation for phytoplankton growth in the subarctic region and nitrogen limitation in the subtropical gyre. Although the growth rate of phytoplankton is determined by the concentration of limiting nutrient, the supply ratio of iron to nitrogen is suggested to be essential to this biogeographic pattern. However, the underlying dynamics determining the ratio remain largely unknown. We investigated mechanisms of dissolved iron (dFe) and nitrate (NO3−) transport to the euphotic zone of the North Pacific using an eddy‐resolvable biogeochemical model. We show that lateral advection and atmospheric deposition are dominant drivers for dFe transport, resulting in high Fe:N supply ratio in both subarctic and subtropical regions. Conversely, significant vertical supplies of NO3− through upwelling and diffusion processes markedly reduce the supply ratio in the subarctic region. These dynamics combined lead to high Fe:N supply ratio in the gyre and low ratio in the subarctic, ultimately driving high nitrogen fixation condition in the gyre and the iron‐limited phytoplankton growth condition in the subarctic region. Plain Language Summary Iron is a critical trace element for the photosynthesis and nitrogen fixation of phytoplankton in the ocean. In North Pacific Subarctic region, although there is plenty of nitrate, the growth of phytoplankton is limited due to the lack of iron. In the North Pacific Subtropical Gyre (NPSG), nutrient supply to the surface is restricted due to ocean stratification, but diazotrophs can fix nitrogen from the atmosphere. However, their growth is also constrained by iron availability. Understanding how nutrients like iron reach the ocean's surface is vital for predicting the productivity of marine life. Our research employed advanced computer models to explore how dissolved iron is transported in the North Pacific. We discovered that lateral transport by ocean currents, followed by atmospheric deposition, is the primary pathway for iron delivery to the sunlit layer of the NPSG. In the Subarctic Gyre, atmospheric deposition and vertical advection are the major sources of iron. However, we found different transport patterns for nitrate, revealing that physical process‐controlled supply ratio of iron to nitrate may determine where different types of phytoplankton thrive in the surface ocean. This research helps understand the complex processes that supply nutrients to ocean surface. Key Points Lateral transport and atmospheric deposition dominate supplies of dissolved iron (dFe) to the euphotic zone of the North Pacific Upwelling and vertical diffusion control nitrate (NO3−) supply in subarctic region Lateral dFe and vertical NO3− transports determine the stoichiometric supply ratio and shape the biogeographic pattern

Trait‐based community analysis provides a new approach to integrate functional ecology with community ecology. However, our understanding of the linkages between root chemical traits and community chemical diversity and assembly is still in its infancy. Environmental filtering and niche differentiation are two opposite driving forces of community assembly based on deterministic niche processes. We hypothesize that environmental filtering is a strong driver of root chemical assembly at a large spatial scale, whereas biogeochemical niche differentiation drives root chemical traits divergence among co‐occurring species at site scale. We analysed the concentrations of 15 elements in the fine roots of 281 species across five forest types of China. Discriminant analysis was used to measure the degree of similarity of root chemical traits at the community level and biogeochemical niche differentiation at the species level. Root chemical traits at the community level showed a systematic shift along environmental gradients. The growth rate‐related dimension represented by root P and Ca was the most important niche dimension associated with community root chemical assembly, driven by large‐scale environmental filters, particularly soils and climate. Biogeochemical niche differentiation of co‐occurring species could be a consequence of reducing nutrient competition, especially the competition for nitrogen. Root chemical traits provide a new dimension for assessing the functional niche and may help improve our understanding of the underlying mechanisms of root chemical assembly from the local to the biome scale. A plain language summary is available for this article. Plain Language Summary

Submarine groundwater discharge (SGD) has received increasing attention over the past 2 decades as a source of nutrients, trace elements and ocean pollutants that may alter coastal biogeochemical cycles. Assessing SGD flows and their impact on coastal marine environments is a difficult task, since it is not easy to identify and measure these water flows discharging into the sea. The aim of this study is to demonstrate the significant usefulness of the freely available thermal infrared (TIR) imagery of the Landsat 8 thermal infrared sensor (TIRS) as an exploratory tool for identifying SGD springs worldwide, from local to regional scales, for long-term analysis. The use of satellite thermal data as a technique for identifying SGD springs in seawater is based on the identification of thermally anomalous plumes obtained from the thermal contrasts between groundwater and sea surface water. In this study, we use the TIR remote sensing (TIR-RS) imagery provided by Landsat 8 at a regional scale and discuss the principle limiting factors of using this technique in SGD studies. The study was developed in karstic coastal aquifers in the Mediterranean Sea basin during different seasons and under diverse meteorological conditions. Although this study demonstrates that freely available satellite TIR remote sensing is a useful method for identifying coastal springs in karst aquifers both locally and regionally, the limiting factors include technical limitations, geological and hydrogeological characteristics, environmental and marine conditions and coastal geomorphology.

With the development of laser technology, the research of novel laser protection materials is of great significance. In this work, dispersible siloxene nanosheets (SiNSs) with a thickness of about 1.5 nm are prepared by the top-down topological reaction method. Based on the Z-scan and optical limiting testing under the visible-near IR ranges nanosecond laser, the broad-band nonlinear optical properties of the SiNSs and their hybrid gel glasses are investigated. The results show that the SiNSs have outstanding nonlinear optical properties. Meanwhile, the SiNSs hybrid gel glasses also exhibit high transmittance and excellent optical limiting capabilities. It demonstrates that SiNSs are promising materials for broad-band nonlinear optical limiting and even have potential applications in optoelectronics.

Adopting waste-to-wealth strategies and circular economy models can help reduce biowaste and add value. For instance, poultry farming is an essential source of protein, and chicken manure can be converted into renewable energy through anaerobic digestion. However, there are a number of restrictions that prevent the utilization of chicken manure in bioenergy production. Here, we review the conversion of chicken manure into biomethane by anaerobic digestion with focus on limiting factors, strategies to enhance digestion, and valorization. Limiting factors include antibiotics, ammonia, fatty acids, trace elements, and organic compounds. Digestion can be enhanced by co-digestion with sludge, lignocellulosic materials, food waste, and green waste; by addition of additives such as chars, hydrochars, and conductive nanoparticles; and by improving the bacterial community. Chicken manure can be valorized by composting, pyrolysis, and gasification. We found that the growth of anaerobic organisms is inhibited by low carbon-to-nitrogen ratios. The total biogas yield decreased from 450.4 to 211.0 mL/g volatile solids in the presence of Staphylococcus aureus and chlortetracycline in chicken manure. A chlortetracycline concentration of 60 mg/kg or less is optimal for biomethanization, whereas higher concentrations can inhibit biomethane production. The biomethane productivity is reduced by 56% at oxytetracycline concentrations of 10 mg/L in the manure. Tylosin concentration exceeding 167 mg/L in the manure highly deteriorated the biomethane productivity due to an accumulation of acetate and propionate in the fermentation medium. Anaerobic co-digestion of 10% of primary sludge to 90% of chicken manure increased the biogas yield up to 8570 mL/g volatile solids. Moreover, chemicals such as biochar, hydrochar, and conducting materials can boost anaerobic digestion by promoting direct interspecies electron transfer. For instance, the biomethane yield from the anaerobic digestion of chicken manure was improved by a value of 38% by supplementation of biochar.