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Aims: Silicon (Si) is an essential element for siliceous organisms, including macrophytes, phytoplankton, and diatoms. Coastal wetlands are critical for bridging the river-estuary-ocean continuum to drive the biogeochemical Si cycles. However, it remains unclear about the contents and distribution patterns of bioavailable Si in soils under various scenarios, and their environmental controls in coastal wetlands. Methods: We conducted a nationwide sampling campaign across ca. 5000 km of coastal wetlands, covering temperate, subtropical, and tropical climates in China, and quantified plant available Si (ASi) using calcium chloride extractable Si (Si-CaCl2). Results: S. alterniflora invasion did not significantly influence ASi content. In contrast, ASi content in the subtropical zone was higher than in the both temperate (medium) and tropical zones (lowest). ASi content was significantly positively correlated with nutrients (i.e., soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP)), soil water content (SWC), clay and silt contents, but negatively with soil bulk density (BD) and sand content. ASi content, in detail, increased with increasing pH (pH < 7) but decreased with increasing pH (pH > 7), showing a quadratic function relationship. Conclusions: ASi in coastal wetlands was predominately directly influenced by pH, particle size, and nutrients of coastal soil, while vegetation compositions and plant-derived lignin (Λ8) inputs illustrated a minor effect on ASi patterns. Mean annual temperature (MAT) and precipitation (MAP) indirectly regulated ASi content via affecting soil geochemistry and nutrients distribution. Taken together, ASi distribution are mostly controlled by primary pedogenesis and specific weathering processes in China's coastal wetlands. [ABSTRACT FROM AUTHOR]

Achieving global food security requires an understanding of the current status and the future trends in the yield gap for cropping systems worldwide. The aim of this study was to scientifically understand the existing yield gap research, recognize the knowledge base and influential articles, and uncover key research themes and how these have evolved over the past three decades. Bibliometric methods were used to analyze articles related to the yield gap available in the largest scientific database, the Web of Science. A total of 6049 relevant articles published from 1993 to 2023 were numerically analyzed for patterns, trends, and clusters. The findings identified a few primary authors of widely cited publications. Geographically, the United States and China were the two major contributors to the publication pool, with articles from China mostly affiliated with the Chinese Academy of Sciences and China Agricultural University, while the United States had a more scattered distribution of affiliated institutions. The research on yield gaps primarily focused on biological factors, such as the effects of crop varieties, agronomic management, climate change, and soil conditions, with a limited exploration of social and economic factors. Within the auspices of the current food issues worldwide, this study provides a thorough view of the progress and key topics in crop yield gap research, contributing to the existing body of knowledge and providing guidance for researchers, policymakers, and stakeholders involved in agricultural productivity enhancement and sustainable food production. Amid the increasing trend in hunger worldwide over the past decade, we thus concluded that, by establishing appropriate benchmarks, re-prioritizing research needs, and focusing on transforming natural resources rather than inputs, the crop yield gap approach can be useful in terms of the clear inclusion of local contexts and socioeconomic constraints. [ABSTRACT FROM AUTHOR]

In this paper, the torsional moment of the right-angle fastener bolt is taken as the main research parameter, and the torsional stiffness performance of the right-angle fastener under different working conditions is studied experimentally. By establishing the moment–rotation relationship model of the node, the mechanical performance and rotation characteristics of the semirigid connection of the node are studied. According to the joint stiffness value determined by the experimental study and the theory of semirigid connection frame with lateral displacement, the calculation formulas of the stiffness correction coefficient α u of the transverse bar and the constraint coefficient K at the end of the vertical bar are derived, and the effective length coefficient μ of the vertical bar and the theoretical value of the stable bearing capacity of the vertical bar under different working conditions are given. Compared with the current standard values, it is found that the theoretical calculation results of the percentage increase of the stable bearing capacity of the vertical bar are 3 to 4 times larger than the standard calculation results when the step distance is reduced. The theoretical calculation method can better consider the semirigid characteristics of the joint and the influence of adjacent members on the stable bearing capacity of the vertical bar. [ABSTRACT FROM AUTHOR]

A standardized soil health scoring system would be a beneficial tool for accessing and interpreting the status of soil health in Florida. However, because of the climate variability and diverse soil types, a soil health soring function designed in one location may not be useful for other places. In this study, we focused on developing scoring functions for Florida soil using a soil health indicator database under different land management practices across Florida. A soil health scoring index for 11 soil health indicators was calculated for 398 soil samples using comprehensive assessment of soil health (CASH), linear or nonlinear scoring function, and additive and weighted‐additive methods. Based on communality and weights of total data sets (TDS), Mehlich‐3 phosphorus (M3P) contributed the most, whereas pH contributed the least to the indices. The nonlinear scoring function had higher scores than other scoring functions. Only mixed cropping systems had significant changes in soil health indicators before and after treatment. The principal component analysis (PCA) showed that OM and M3P had the highest loading values compared with other indicators. Therefore, OM and M3P need to be considered if minimum number of indicators is to be measured while examining soil health indices pertinent to Florida soil types and land management practices. Overall, the findings of this study provide a foundation for creating and enhancing soil health indices in Florida. Core Ideas: Numerous viable options to estimate soil health index exist to use for Florida soils.Nonlinear scoring function had higher scores than linear scoring functions.Cover crop mixed with organic amendment seems to be a good practice to improve soil health in mineral soils.Organic matter and Mehlich‐3 phosphorus had higher influence in Florida mineral soil in terms of minimum data set. [ABSTRACT FROM AUTHOR]

To trace the phosphorus (P) and potassium (K) content in flooded rice (Oryza sativa L), 14 rice cultivars commonly grown in the Southern United States were evaluated for their P and K concentration in tissue and grain. Field experiments were conducted at two locations in Everglades Agriculture Area (EAA), where flooded rice was cultivated on organic Histosols. Soil pH and Mehlich-3 phosphorus (M3P) were significantly different between locations. At Site I, soil pH, M3P, and Mehlich-3 potassium (M3K) varied in the range of 6.8–7.1, 21.4–36.4 mg kg−1, and 53.9–151.0 mg kg−1, respectively. At Site II, soil pH, M3P and M3K varied in the range of 6.9–7.3, 11.2–20.5 mg kg−1, and 64.8–104.1 mg kg−1, respectively. Stem potassium was the only measured parameter that was significantly different among rice cultivars at both sites. At Site I and Site II, stem K ranged from 14.2–26.6 mg kg−1 and 10.4–19.4 mg kg−1, respectively. No significant difference in yield among cultivars was observed at Site I, whereas Site II had a significant difference in yield among cultivars. At Site I and Site II, yields ranged from 3745–7587 kg ha−1 and 2627–6406 kg ha−1, respectively. None of the cultivars ranked consistently in the same top and bottom position for each measured parameter. Total phosphorus (TP) concentration was highest in grain, whereas total potassium (TK) concentration was highest in the stem. Results suggest incorporation of rice stem into the soil could potentially add fertilizer back to the soil which helps in fertility management. [ABSTRACT FROM AUTHOR]

Elevated CO2 concentration [e(CO2)] often promotes plant growth with a decrease in tissue N concentration. In this study, three experiments, two under hydroponic and one in well-watered soil, including various levels or patterns of CO2, humidity, and N supply were conducted on wheat (Triticum aestivum L.) to explore the mechanisms of e[CO2]-induced N deficiency (ECIND). Under hydroponic conditions, N uptake remained constant even as transpiration was limited 40% by raising air relative humidity and only was reduced about 20% by supplying N during nighttime rather than daytime with a reduction of 85% in transpiration. Compared to ambient CO2 concentration, whether under hydroponic or well-watered soil conditions, and whether transpiration was kept stable or decreased to 12%, e[CO2] consistently led to more N uptake and higher biomass, while lower N concentration was observed in aboveground organs, especially leaves, as long as N supply was insufficient. These results show that, due to compensation caused by active uptake, N uptake can be uncoupled from water uptake under well-watered conditions, and changes in transpiration therefore do not account for ECIND. Similar or lower tissue NO 3 - -N concentration under e[CO2] indicated that NO 3 - assimilation was not limited and could therefore also be eliminated as a major cause of ECIND under our conditions. Active uptake has the potential to bridge the gap between N taken up passively and plant demand, but is limited by the energy required to drive it. Compared to ambient CO2 concentration, the increase in N uptake under e[CO2] failed to match the increase of carbohydrates, leading to N dilution in plant tissues, the apparent dominant mechanism explaining ECIND. Lower N concentration in leaves rather than roots under e[CO2] validated that ECIND was at least partially also related to changes in resource allocation, apparently to maintain root uptake activity and prevent more serious N deficiency. [ABSTRACT FROM AUTHOR]

Increasing dietary fiber intake is considered to be an effective way to prevent and relieve the diseases associated with high‐income lifestyles. Compared with soluble dietary fiber, comprehensive evaluation about the effects of insoluble dietary fiber on hyperlipidemia is rarely studied. In the present study, the insoluble dietary fiber was extracted from defatted rice bran by enzymatic treatments (IDF‐dRB), followed by investigation about the adsorption and antioxidant activities in vitro. Moreover, the alleviating effects of IDF‐dRB on hyperlipidemia were evaluated and analyzed. As a result, IDF‐dRB possessed good adsorption capacities of glucose and cholesterol, and also exhibited excellent properties in scavenging radicals. Furthermore, intervention with IDF‐dRB significantly improved lipid and glucose metabolism and alleviated inflammation and oxidative stress in rats fed high‐fat diet. It was also observed that IDF‐dRB treatment could recover the decline in species of gut microbiota caused by high fat diet, increase the community richness, and modulate the metabolic function of gut microbiota. In conclusion, the results indicated that IDF‐dRB could ameliorate hyperlipidemia from many aspects and offered some perspectives about the effects of diet intervention with insoluble dietary fiber. Practical Application: Rice bran and defatted rice bran are coproducts in the rice processing industry and potentially valuable for the preparation of insoluble dietary fiber. Here an insoluble dietary fiber IDF‐dRB was extracted from defatted rice bran and showed good properties in improving lipid and glucose levels, alleviating inflammation and oxidative stress, and modulating gut microbiota in rats fed high‐fat diet, suggesting the potential application in ameliorating hyperlipidemia. [ABSTRACT FROM AUTHOR]

Rice straw can adsorb Cd(II) from wastewater, and modification of rice straw may improve its adsorption efficiency. The rice straw powder (Sp) from the direct pulverization of rice straw was used as the control, the rice straw ash (Sa), biochar (Sa), and modified rice straw (Ms) were prepared by ashing, pyrolysis and citric acid modification, respectively, and all of them were examined as adsorbents for Cd(II) in this study. Batch adsorption experiments were adopted to systematically compare the adsorption capacities of rice straw materials prepared with different modification methods for Cd(II) from aqueous solution under different levels of initial Cd(II) concentration (0–800 mg·L−1), temperature (298, 308, and 318 K), contact time (0–1440 min), pH value (2–10), and ionic strength (0–0.6 mol·L−1). The results indicated that the modification method affected the adsorption of Cd(II) by changing the specific surface area (SSA), Si content, surface morphology, and O-containing functional group of rice straw. Compared with Sp, Ms held more surface O–H, aliphatic and aromatic groups, while Sa had more phenolic, C–O (or C–O–C), and Si–O groups, and Sb held more C–O (or C–O–C) and Si–O groups; besides, Sa, Sb, and Ms had larger SSA than Sp. Adsorption capacity of the four adsorbents for Cd(II) increased and gradually became saturated with the increase in the initial Cd(II) concentration (0–800 mg·L−1). The adsorption capacity of Cd(II) was significantly higher at 318 K than 298 K and 308 K, regardless of the adsorbent type. Sa had the largest SSA (192.38 m2·g−1) and the largest adsorption capacity for Cd(II). When the initial Cd2+ concentration was at 800 mg·L−1, the Cd(II) adsorption amount reached as high as 68.7 mg·g−1 with Sa at 318 K. However, the SSA of Sp was only 1.83 m2·g−1, and it had the least adsorption capacity for Cd(II). Only the adsorption of Cd(II) upon Sb at 298 K was spontaneous, and surprisingly, all other adsorptions were nonspontaneous. These adsorptions were all chemical, and were favorable, exothermic and order-increasing processes. The pseudo-second-order model showed a strong fit to the kinetics of Cd(II) adsorption by the four adsorbents. The adsorption capacities of Cd(II) by the adsorbents were less at low pH, and all were enhanced with the increase of initial pH value (2–10) in the solution. The inhibiting effect on Cd(II) adsorption due to the increase in ionic strength was greater with Sa, Sb, and Ms than that under Sp. The rice straw ash prepared by ashing unexpectedly had greater adsorption capacity for Cd(II) than the biochar and citric acid modified rice straw. The optimum condition for Cd(II) adsorption was established as the temperature of 318 K, initial Cd(II) concentration of 800 mg·L−1, contact time of 240 min, and no Na(I) interference regardless of absorbent. In conclusion, rice straw ash shows the greatest potential of being applied to paddy fields for the remediation of Cd(II) pollution so as to reduce the risk of Cd(II) enrichment in rice grains and straws. [ABSTRACT FROM AUTHOR]

In the research of dynamic load identification, the method of obtaining kernel function matrix is usually rather cumbersome. To solve this problem, an explicit dynamic load identification algorithm based on the Wilson-θ (DLIAEW) method is proposed to easily obtain the kernel function matrix as long as the parameters of the system are known. To aim at the ill-posed problem in the inverse problem, this paper improves the Tikhonov regularization, proposes an improved regularization algorithm (IRA), and introduces the U-curve method to determine the regularization parameters. In the numeric simulation investigation of a four dofs vibrating system, effects of the sampling frequency and the noise level on the regularization parameters and the identification errors of impact and harmonic loads for the IRA are discussed in comparison with the Tikhonov regularization. Finally, the experiments of a cantilever beam excited by impact and harmonic loads are carried out to verify the advantages of the IRA. [ABSTRACT FROM AUTHOR]