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In this paper, to address the problem that the traditional fal function constitutes an active disturbance rejection control (ADRC) system that is greatly affected by feedback signal noise and the control output has jitter, propose a continuous and smooth Hfal function in the definition domain to improve the extended state observer and nonlinear error feedback control law in ADRC. Firstly, the characteristic curves and error gain curves of the fal function and Hfal function are compared and analyzed to prove the feasibility and superiority of the Hfal function; secondly, the convergence condition of the extended state observer improved by the Hfal function is analyzed theoretically, and the simulation of the improved extended state observer with glan , faln , and tanh function is compared in the observed signal containing noise to verify the improved extended state observer with Hfal function has higher observation accuracy; finally, the improved ADRC (IADRC) method is applied to the magnetically levitated sphere system model with a nonlinear, large time lag and strong coupling characteristics for discretization simulation experiments, and the results show that the proposed IADRC method solves the output jitter problem of the traditional ADRC method, has better stability, and has stronger robustness to large-amplitude control quantity step disturbances and feedback link noise. The proposed control method further improves the control performance of the system and has a good reference value for the control of other nonlinear systems with uncertain disturbances.

A highly efficient cascade cyclization of phenidones and enynones has been developed via a Ru(II)-catalyzed C-H activation initiated indole formation/Diels-Alder reaction/iminium ion cyclization sequence, which afforded hexacyclic indolines as single diastereomer in good to excellent yields with a broad substrate scope under mild conditions. The reaction features the simultaneous generation of five new chemical bonds and four new rings in one pot, providing a rapid and concise approach toward polycyclic indoline alkaloids and their analogues.

A rhodium-catalyzed diastereoselective formal [5 + 2] annulation of indoles with cyclohexadienone-containing 1,6-enynes has been established via indole 2,3-difunctionalization. The reaction, probably proceeding through tandem indole C2-H alkenylation and intramolecular Friedel-Crafts alkylation relay, provides rapid construction of indole-fused oxepines in good to excellent yields with a broad substrate scope. This method also features concomitant construction of cis-hydrobenzo[b] oxepine scaffolds, a core unit found in numerous natural products of important biological activities.

An efficient Cp*RhIII-catalyzed formal C(sp3)–H activation/spiroannulation of alkylidene Meldrum’s acids with alkynes has been developed using catalytical Cu(OAc)2 and air as the oxidant. This reac...

An efficient regioselective and stereoselective cascade annulation of indoles with alkynediones has been demonstrated via a Cp*RhIII-catalyzed indole C2–H activation by using N-carboamide directing groups in good to excellent yields with a broad substrate scope, which further realized the C2 and C3 difunctionalization of indoles in one-pot. This methodology simultaneously provides a novel and straightforward approach to free (NH) tetrahydrocarbazoles with continuous quaternary carbons and pyridoindolones, which are valuable intermediates in total synthesis of the related indole alkaloids.

Cyclophosphamide, one of the earliest prescribed alkylating anticancer drugs, has been frequently detected in aquatic environments. However, its effects on fish behavior and associated mechanisms remain largely unknown. In this study, the behaviors, neurochemicals, and gut microbiota of adult zebrafish were investigated after 2 months of exposure to CP at 0.05, 0.5, 5, and 50 µg/L. Behavioral assays revealed that CP increased locomotion and anxiety, and decreased the cognition of zebrafish. The alteration of neurotransmitters and related gene expressions in the dopamine and gamma-aminobutyric acid pathways induced by CP may be responsible for the observed changes in locomotion and cognition of adult zebrafish. Meanwhile, CP increased the anxiety of adult zebrafish through the serotonin, acetylcholine, and histamine pathways in the brain. In addition, increased abundances of Fusobacteriales, Reyanellales, Staphylococcales, Rhodobacterals, and Patescibateria in the intestine at the CP-50 treatment were observed. The study has demonstrated that CP affects the locomotion, anxiety, and cognition in zebrafish, which might be linked with the dysfunction of neurochemicals in the brain. This study further suggests that the gut-brain axis might interact to modulate fish behaviors upon exposure to CP (maybe other organic pollutants). Further research is warranted to test this hypothesis.

Sediments are the major sink for selenium (Se) in aquatic environments. Se speciation in sediments is crucial for its bioavailability and the toxicity in benthos but this is relatively understudied. In this study, selenite (Se(IV)) and seleno-L-methionine (Se-Met) were respectively added to sediments for 90 and 7 days, and the accumulation and depuration of Se in the oligochaete Lumbriculus variegatus was investigated. The background levels of Se in the river sediments, fish flakes, and L. variegatus were also detected. Without the presence of worms, the levels of Se(IV) in the sediments were relatively stable within 7 d but showed a decreasing trend during the 90 d of aging. In contrast, Se-Met in the sediments showed a sharp decrease within 3 d of aging. The LC50-96h values of Se(IV) and Se-Met in L. variegatus were 372.6 and 9.4 µg/g. Interestingly, the dominant Se species in Se(IV)- or Se-Met-treated L. variegatus was Se-Met, whose levels were increased with time in 7 days of exposure. Se was barely depurated from L. variegatus during the 8 d of depuration period. This study has provided indispensable data on the levels of total Se in the abiotic and biotic matrices and the biodynamics of Se in a representative benthos, which could better understand the ecological risk of Se to the freshwater benthic communities.

A highly efficient Ru(II)-catalyzed regio- and stereospecific hydro-oxycarbonylation of unsymmetrical internal alkynes bearing a difunctional 2-pyridyloxy directing group with carboxylic acids has been developed, which provides allylic (

We report a phosphine-catalyzed ring opening of electron-deficient alkylidenecyclopropanes (ACPs) to generate allylic phosphonium zwitterions that resemble the well-studied phosphine-allene adducts but exhibit distinct properties. The potent reactivity of these intermediates has been demonstrated in three types of substrate-controlled phosphine-catalyzed rearrangements of alkylidenecyclopropylketones, which chemoselectively afford tri- and tetrasubstituted furans, and trisubstituted dienones in good yields.

Understanding cadmium (Cd) extractability and transfer in soil-plant system is crucial for the evaluation of the remediation effect of Cd-contaminated soils. However, knowledge on the effects of different phosphorus (P) fertilizers on Cd uptake in plants, root morphology, and Cd extractability in rhizosphere soils remains very limited. In this study, a five-year field experiment was conducted to evaluate the impacts of four P fertilizers (i.e. calcium superphosphate, calcium magnesium phosphate, monopotassium phosphate, and compound fertilizer) on Cd uptake in maize (Zea mays L.), root morphology, and Cd extractability in rhizospheric acidic soils contaminated with Cd. The results showed that compared to the control, the contents of rhizospheric DTPA-Cd were respectively 18-40% and 8-29% lowered by the calcium magnesium phosphate and monopotassium phosphate, but 21-59% and 10-36% elevated by the calcium superphosphate and compound fertilizer. Similar effects of P fertilizers were observed on exchangeable Cd. Furthermore, the altered levels of the DTPA-Cd and exchangeable Cd in the rhizospheric soils were greater than those in the non-rhizospheric soils. Moreover, different P fertilization regimes altered the contents of Cd in maize tissues (roots, stems, leaves, and grains), and the alterations were closely related to the variation of DTPA-Cd and exchangeable Cd in the rhizospheric soils. Meanwhile, different P fertilization regimes enhanced root morphological parameters (root length, surface area, and volume), and the activities of urease and surcase. In general, the lowest concentrations of soil DTPA-Cd and Cd in maize tissues were found in the treatments with calcium magnesium phosphate. This study has demonstrated that the calcium magnesium phosphate can be used as a potential amendment agent for the acidic Cd-contaminated soils cultivated with maize.

Reinforcement Learning (RL) based methods optimize evaluation metric directly in image captioning task. In these methods, metric scores of captions are regard as rewards for examples. However, existing methods suffer from inferior performances on hard examples. In this paper, we propose an adaptive hard example mining method with additional supervised training for image captioning. Beam search algorithm is leveraged to estimate score expectation for each example. Examples whose caption scores are lower than expectation are selected automatically. For the selected hard examples, we propose an additional reward policy for high-scoring captions to force model learning from them. The proposed method is hyper-parameter free without tuning. Experimental results on MSCOCO dataset validate effectiveness of the proposed method.

Alkynylcyclopropanes have been used for the first time as coupling partners in transition-metal-catalyzed C–H functionalization. Specifically, a Cp*RhIII-catalyzed regioselective annulation of alkynylcyclopropanes with N-aryloxyamides via redox-neutral C–H/C–C activation has been developed, which affords highly functionalized 2,3-dihydrobenzofurans bearing an (E)-exocyclic carbon–carbon double bond and a tetra-substituted carbon center in moderate to good yields with a broad substrate scope.

Soil physical quality (SPQ) is an important parameter for crop growth. Tillage management is widely recognized to affect SPQ remarkably, but such an effect is complicated in Vertisols by shrinking and swelling soil structure. The objectives of this study were to (i) investigate how tillage practices affected SPQ as indicated by the S index, least limiting water range (LLWR) and water stress percentage (WSP); and (ii) determine the relationship between these SPQ indicators and crop yield. A 4-year field experiment, which was conducted in a Vertisol under wheat-maize rotation system in the North China Plain, consisted of four tillage treatments: no tillage (NT), rotary tillage (RT), subsoiling (SS), and deep ploughing (DP). Soil water retention curve (SWRC), soil shrinkage curve (SSC), penetration resistance (PR), and bulk density (BD) of the 0−10 and 10−20 cm layer were measured during wheat and maize seasons, and soil water content was continuously monitored in situ. The S index, LLWR and WSP were determined. Our results showed that SSCs were parallel to each other among four tillage treatments, indicating that tillage did not impact shrinkage capacity (P > 0.05). Relative to NT and RT treatments, the SS and DP treatments improved soil physical quality (higher S index and larger LLWR), particularly in the 10−20 cm layer. The S index presented a poor relation with wheat (P > 0.05) and maize yields (P > 0.05), while LLWR had a significant correlation with wheat yield (P 0.05). A new proposed SPQ indicator, WSP, is defined as the percentage of the period when the soil water content is above the field water capacity (waterlogging stress percentage, WLP) or below the wilting point (drought stress percentage, DSP) to the entire crop season period. The WLP presented a significantly negative relation with maize yield (P 0.05), whereas the DSP had no relation with wheat and maize yield (P > 0.05). Moreover, the WSP was observed to be independent of the volume change in the Vertisol. Our results demonstrate that LLWR and WLP can be regarded as suitable indicators for evaluating SPQ in wheat and maize seasons, respectively, but the latter is more conveniently applied in a Vertisol.

Exudation of low-molecular-weight organic acids (LMWOAs) from plant roots enhances phosphorus (P) acquisition from soil, either by dissolving P fixed in secondary minerals or by reducing P sorption to organo-minerals. How LMWOAs may modify P sorption in soils with contrasting pH is not well understood, much less the mechanisms involved. The effects of three common LMWOAs (oxalic, citric, and malic acids) on P sorption in calcareous, neutral, and acidic soils were studied in batch experiments, followed by sequential P fractionation to elucidate the mechanisms whereby LMWOAs alter P sorption. The sorption data of the three soils fitted better to the Freundlich equation (r2 = 0.325–0.994, P −1 soil decreased the Freundlich P sorption parameters Kf and n, which represent P sorption capacity and energy, due to the fact that LMWOAs reduced P sorption in NaHCO3-Pi (soil soluble and exchangeable Pi, 23.8–30.9%) and NaOH-Pi (Fe-Pi and Al-Pi, 21.6–54.2%) fractions of the three soils. Comparing acidified P-LMWOAs solutions with the pH-adjusted P-LMWOAs solutions (pH = 7) had a minor effect on P sorption. Our results indicated that the reduction in soil P sorption was due to ligand exchange and chelation of LMWOAs with Fe and Al minerals, and the acid strength of LMWOAs had a minor effect on P sorption in calcareous, neutral, and acid soils.

Nitrogen derived from rhizodeposition (NdfR) is an important N source both for the current and subsequent crops in soil-plant system. However, few studies have focused on the effects of elevated O 3 concentration on NdfR and its availability to subsequent crops. A pot experiment was conducted to investigate the effects of elevated O 3 on spring wheat NdfR and its availability to buckwheat in open-top chambers (OTCs), where spring wheat was labeled with 15 N urea by using a split-root method under ambient (Control; CK) and two O 3 concentration-elevated conditions (60 ± 5 and 110 ± 5 nmol mol −1 , respectively), and buckwheat was cultivated in the soil contained rhizodeposited 15 N compounds after spring wheat harvest. The results showed that O 3 stress significantly decreased the quantity of spring wheat 15 N rhizodeposition ( 15 NdfR) by 24–48% compared to CK. Spring wheat 15 NdfR accounted for on average 8–15% of the total plant 15 N ( 15 N assimilation in plant material + 15 NdfR; T 15 N), and 78–95% of the total belowground parts of plant 15 N (root 15 N + 15 NdfR; BGP- 15 N) during plant growth. N recovery of buckwheat plant accounted for 12–25% of spring wheat 15 N deposited into soil, and was significantly decreased by approximately one half under the two O 3 level-elevated conditions. These results indicate that N rhizodeposition represents a significant pool in N dynamics of soil-plant system, and the projected future O 3 concentration might induce adverse effects on NdfR and its availability to subsequent crops to influence N transformation and cycling in soil-plant system.

As labile fraction of soil organic matter, soil carbohydrates are sensitive to environmental changes due to their high turnover rates. The effects of elevated O 3 and CO 2 on the concentration and composition of soil carbohydrates in agroecosystems have been rarely studied. The present experiment was conducted to investigate the dynamics of the concentration and composition of neutral sugars in soil under the influence of elevated O 3 and CO 2 with different N application rates (150 kg N ha −1 and 225 kg N ha −1 ). Our results showed that elevated O 3 decreased soil carbohydrate accumulation, with the effect being more pronounced with high than with low N application rate. Elevated O 3 significantly increased the ratio of (mannose + galactose)/(arabinose + xylose), indicating that elevated O 3 promoted the relative contribution of microbe-derived carbohydrates to soil organic matter (SOM). The high N application rate further increased the contribution of microbe-derived carbohydrates to SOM under elevated O 3 conditions. However, elevated CO 2 had no effect on soil carbohydrate accumulation and little effects on carbohydrate composition in the study soil, regardless of N application rates. The elevated O 3 -induced effects were not altered by elevated CO 2 at the low N application rate, and the change in composition mediated by elevated CO 2 was observed only at the high N application rate. Our results suggest that elevated O 3 affected soil carbohydrate accumulation and their composition and that the effects on composition were mediated by elevated CO 2 and N application rates.

Much nitrogen (N) is lost in high-input protected cropping systems mainly via leaching of not only nitrate-N but also extractable organic N (EON), but the role of EON in this process is poorly appreciated. A consecutive 3-year plot experiment was conducted to investigate the impact of co-application of manures with chemical N fertilizer on N accumulation and loss in a greenhouse soil rotationally planted with cucumber or tomato and lettuce. Application of manures significantly enhanced the average contents and stocks of NO3−-N, EON, and total N (TN) in 0- to 60-cm soil layer, although EON accumulated within growing season, while NO3−-N accumulated with fluctuation, and TN accumulated gradually throughout the 3-year experiment. With application rate at 120 or 180 t dry manures per hectare per 3 years, the corresponding apparent N surplus was 2710 or 3924 kg⋅ha−1 per 3 years. Due to little increase of biomass N uptakes during vegetable seasons, the accumulated N in soil profile would be a potential loss source, largely via leaching of both nitrate and EON. Application of manures slowed soil acidification but intensified secondary salinization of the greenhouse soil. Considering the manures-induced high soil N accumulation and loss, well-balanced evaluation of the role of manures in high-input agricultural ecosystems is needed.

Phosphorus (P) fertilizer prices rose more than 150 % in the past two decades, thus periodic P fertilization (purchasing and applying superphosphate periodically) could be economically beneficial to small-holder farmers. Still, it is necessary to determine if periodic P fertilization could sustain corn production compared to annual P fertilization. Corn (Zea mays L.) obtains P for its growth and development from soil solution, which is replenished by soil P fractions associated with the soil minerals (inorganic P, Pi) and organic matter (organic P, Po). It is expected that P fertilization regimes (annual vs. periodic applications) will influence the concentration of soil P fractions contributing to corn P nutrition. The objective of the study was to evaluate soil Pi and Po fractions and P uptake in corn agroecosystems of Northeast China under two fertilizer regimes: triple-superphosphate applied annually at 0, 25 or 75 kg P ha−1, or applied periodically (once every 6 years) as 150 or 450 kg P ha−1. During the two 6-year periods (1997–2002 and 2003–2008), both periodic and annual triple-superphosphate application significantly (P < 0.05) increased the NaHCO3-Pi (93–453 %), NaOH-Pi (44–135 %) and HCl-Pi (11–45 %) fractions, thus sustaining crop P requirements. Although annual P fertilization gave 35 % more NaHCO3-Pi, 28 % more NaOH-Pi, 15 % greater HCl-Pi and 4 % more crop P uptake at the end of each 6-year period, there was no significant difference in corn yield. Therefore, periodic P application (once in 6 years) is recommended as an economical practice that could lower the cost of P fertilization for small-holder farmers producing corn in Northeast China.

Low molecular weight organic acids exuded by plants roots enhance inorganic P i release into soil solution and thereby increases plant-available Pi in soils. Low molecular weight organic acids may also induce organic P (P o ) release into soil solution, but kinetics of both Pi and Po displacement from the soil matrix into soil solution of agricultural soils is poorly understood, and the mechanism for P o release is not well explained. This study used kinetic experiments to determine the concentrations and release rates of P i and P o induced by oxalic acid, citric acid, and malic acid in calcareous, neutral and acidic soils. Kinetic data were well described by Elovich (r 2 = 0.801–0.993, P citric acid (0.61–2.82 mg kg –1 ) > malic acid (0.52–1.76 mg kg –1 ) and mainly resulted from the release of labile P o (NaHCO 3 -P o ) regardless of soil type. By contrast, oxalic acid was most effective in enhancing P i release from the HCl-P i (Ca-P i ) fraction of the calcareous soil, and citric acid was most effective in releasing Pi from the NaOH-Pi (Fe/Al-Pi) fraction of the neutral and acidic soils. Therefore, the mechanism for the kinetics of P o release induced by low molecular weight organic acids is ascribed to their ability to mobilize the labile P o (NaHCO 3 -P o ) rather than their ability to chelate cations (i.e. ,F e 3+ ,A l 3+ ) bound to P o in soil.

Soil carbohydrates are sensitive to changes in soil C inputs because of their fast turnover rates. However, the effects of elevated O 3 on the content and composition of soil carbohydrates are rarely reported in agroecosystem. The objectives of this study were to investigate the effects of elevated O 3 on the content and composition of soil neutral sugars in the two wheat cultivars with different O 3 -tolerance. Our results showed that elevated O 3 decreased the total soil neutral sugars. At the wheat ripening stage, elevated O 3 increased the contents of galactose (Gal), arabinose (Ara) and mannose (Man) in the O 3 -tolerant wheat and decreased the contents of xylose (Xyl), Gal and Ara in the O 3 -sensitive wheat. Significant interactive effects between elevated O 3 and wheat cultivar were found in the ratios of (Man + Gal)/(Ara + Xyl) and Man/(Ara + Xyl). These two ratios increased with elevated O 3 at the wheat ripening stage in both wheat cultivars, with higher ratios observed in the O 3 -sensitive wheat relative to the O 3 -tolerant wheat. Our results indicated that elevated O 3 decreased the total neutral sugars and altered the relative contribution of plant- and microbe-derived carbohydrates to soil organic matter. Microbe-derived carbohydrates were dominant contribution to the total carbohydrates in the O 3 -sensitive wheat. These changes in the accumulation and origins of soil carbohydrates will influence the accumulation and decomposition of soil organic matter and ecosystem functioning in agroecosystem.

Enhancement of inorganic phosphorus (Pi) release by low molecular weight organic acids (LMWOA) increases soil phosphorus (P) availability to plant, but the release of organic phosphorus (Po) and the associated kinetics of both Pi and Po release by LMWOA have not been well considered. The aim of this study was therefore to investigate the impacts of three common LMWOA (citric acid, oxalic acid, and malic acid) on the kinetic release of Pi and Po in a black clay soil in northeast China. All kinetic data were well described by the Elovich and power functions models (P citric acid (2.67 mg kg−1) > malic acid (1.76 mg kg−1). In contrast, Pi release by LMWOA resulted from mobilization of the moderately labile NaOH-Pi (Fe/Al-P) and HCl-Pi (Ca-Pi) fractions in the order of citric a...

Soil extractable organic nitrogen plays an important role in nitrogen transformation and migration in many ecosystems. However, it is generally ignored due to its low content in agricultural soils. The objective of this study was to evaluate the leaching risk of soil extractable organic nitrogen affected by manure application in an intensively irrigated greenhouse vegetable cropping system through investigating its spatial (vertical profile) and temporal dynamics. Results showed that extractable organic nitrogen was present in appreciable quantities, despite that nitrate was the main soluble nitrogen form in 0–60 cm soil profile. Both the extractable organic and inorganic nitrogen were enriched in the surface and subsurface soils, and showed a high temporal variability throughout the cucumber growing season. Manure application increased the stocks of extractable organic nitrogen significantly in the soil profile. Average extractable organic nitrogen reserves in 0–60 cm layer were 47, 71, and 131 kg ha−1 f...