High-order sliding mode observer-based trajectory tracking control for a quadrotor UAV with uncertain dynamics

This paper investigates the trajectory tracking problem of the quadrotor unmanned aerial vehicles (UAV) with consideration of both attitude and position dynamics. First of all, the trajectory tracking problem is divided into the commands tracking in position and attitude loops by introducing the virtual attitude angle commands. Secondly, the high-order sliding mode observers (HSMOs) are introduced to estimate the lumped disturbances in position loop and the derivatives of the attitude angle tracking errors, the lumped disturbances in the attitude loop. And then the composite nonlinear dynamical inversion controller in position loop and the composite nonsingular terminal sliding mode controller in attitude loop are constructed by introducing the estimation information of HSMOs into controller design process. Finally, the simulations based on the data of a practical UAV are carried out to verify the effectiveness of the proposed method

Bilateral continuous terminal sliding mode control for teleoperation systems with high-order disturbances

A new bilateral continuous terminal sliding mode control method is proposed to attenuate the high-order time-varying disturbance in teleoperation systems based on enhanced nonlinear disturbance observer (ENDOB). Firstly, the control task of the teleoperation systems is transformed into stabilization of the position and force tracking errors. And then, the ENDOBs are introduced to estimate the high-order lumped disturbances in position and force tracking error subsystems. Finally, based on the estimation of lumped disturbances, a bilateral continuous terminal sliding mode controller is developed. The proposed bilateral controller not only guarantees the continuity of the control action but also guarantees the position and force tracking errors converge to a small bounded region even when there exist high-order time-varying disturbances. The effectiveness of the proposed method is validated by its applications on a bilateral lift robot system

DataSheet_1_C-terminally encoded peptide-like genes are associated with the development of primary root at qRL16.1 in soybean.pdf

Root architecture traits are belowground traits that harness moisture and nutrients from the soil and are equally important to above-ground traits in crop improvement. In soybean, the root length locus qRL16.1 was previously mapped on chromosome 16. The qRL16.1 has been characterized by transcriptome analysis of roots in near-isogenic lines (NILs), gene expression analysis in a pair of lines contrasting with alleles of qRL16.1, and differential gene expression analysis in germplasm accessions contrasting with root length. Two candidate genes, Glyma.16g108500 and Glyma.16g108700, have shown relatively higher expression in longer root accessions than in shorter rooting accessions. The C-terminal domain of Glyma.16g108500 and Glyma.16g108700 is similar to the conserved domain of C-terminally encoded peptides (CEPs) that regulate root length and nutrient response in Arabidopsis. Two polymorphisms upstream of Glyma.16g108500 showed a significant association with primary root length and total root length traits in a germplasm set. Synthetic peptide assay with predicted CEP variants of Glyma.16g108500 and Glyma.16g108700 demonstrated their positive effect on primary root length. The two genes are root-specific in the early stage of soybean growth and showed differential expression only in the primary root. These genes will be useful for improving soybean to develop a deep and robust root system to withstand low moisture and nutrient regimes.</p

Probing and Comparing the Photobromination and Photoiodination of Dissolved Organic Matter by Using Ultra-High-Resolution Mass Spectrometry

Photochemical halogenation of dissolved organic matter (DOM) may represent an important abiotic process for the formation of natural organobromine compounds (OBCs) and natural organoiodine compounds (OICs) within surface waters. Here we report the enhanced formation of OBCs and OICs by photohalogenating DOM in freshwater and seawater, as well as the noticeable difference in the distribution and composition pattern of newly formed OBCs and OICs. By using negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry, various OBCs and OICs were identified during the photohalogenation processes in sunlit waters. The respective number of OBCs and OICs formed in artificial seawater (ASW) under light radiation was higher than that in artificial freshwater (AFW), suggesting a possible role of the mixed reactive halogen species. OBCs were formed mainly via substitution reactions and addition reactions accompanied by other reactions and distributed into three classes: unsaturated hydrocarbons with relatively low oxygen content, unsaturated aliphatic compounds, and saturated fatty acids and carbohydrates with relatively high hydrogen content. Unlike the OBCs, OICs were located primarily in the region of carboxylic-rich alicyclic molecules composed of esterified phenolic, carboxylated, and fused alicyclic structures and were generated mainly through electrophilic substitution of the aromatic proton. Our findings call for further investigation on the exact structure and toxicity of the OBCs and OICs generated in the natural environment

Table_1_C-terminally encoded peptide-like genes are associated with the development of primary root at qRL16.1 in soybean.xlsx

Root architecture traits are belowground traits that harness moisture and nutrients from the soil and are equally important to above-ground traits in crop improvement. In soybean, the root length locus qRL16.1 was previously mapped on chromosome 16. The qRL16.1 has been characterized by transcriptome analysis of roots in near-isogenic lines (NILs), gene expression analysis in a pair of lines contrasting with alleles of qRL16.1, and differential gene expression analysis in germplasm accessions contrasting with root length. Two candidate genes, Glyma.16g108500 and Glyma.16g108700, have shown relatively higher expression in longer root accessions than in shorter rooting accessions. The C-terminal domain of Glyma.16g108500 and Glyma.16g108700 is similar to the conserved domain of C-terminally encoded peptides (CEPs) that regulate root length and nutrient response in Arabidopsis. Two polymorphisms upstream of Glyma.16g108500 showed a significant association with primary root length and total root length traits in a germplasm set. Synthetic peptide assay with predicted CEP variants of Glyma.16g108500 and Glyma.16g108700 demonstrated their positive effect on primary root length. The two genes are root-specific in the early stage of soybean growth and showed differential expression only in the primary root. These genes will be useful for improving soybean to develop a deep and robust root system to withstand low moisture and nutrient regimes.</p

Molecular-Scale Investigation with ESI-FT-ICR-MS on Fractionation of Dissolved Organic Matter Induced by Adsorption on Iron Oxyhydroxides

Adsorption by minerals is a common geochemical process of dissolved organic matter (DOM) which may induce fractionation of DOM at the mineral-water interface. Here, we examine the molecular fractionation of DOM induced by adsorption onto three common iron oxyhydroxides using electrospray ionization coupled with Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). Ferrihydrite exhibited higher affinity to DOM and induced more pronounced molecular fractionation of DOM than did goethite or lepidocrocite. High molecular weight (>500 Da) compounds and compounds high in unsaturation or rich in oxygen including polycyclic aromatics, polyphenols and carboxylic compounds had higher affinity to iron oxyhydroxides and especially to ferrihydrite. Low molecular weight compounds and compounds low in unsaturation or containing few oxygenated groups (mainly alcohols and ethers) were preferentially maintained in solution. This study confirms that the double bond equivalence and the number of oxygen atoms are valuable parameters indicating the selective fractionation of DOM at mineral and water interfaces. The results of this study provide important information for further understanding the behavior of DOM in the natural environment

Relationship between Molecular Components and Reducing Capacities of Humic Substances

Humic substances (HSs) are collections of diverse organic compounds with broad redox capacities, which directly or indirectly affect the biogeochemical behaviors and fates of almost all the pollutants in the environment. The present study investigates the relationships between the molecular characteristics of HSs and their reducing capacities or electron-donating capacities (EDCs) by electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), total phenolic assay, and mediated electrochemical oxidation analysis. For decreasing the molecular heterogeneity of bulk HSs, HSs were first separated into three fractions according to their polarities. The results demonstrated that compounds in HS fractions with moderate polarity possessed a high content of total phenols and consistently had high EDCs. A strong linear correlation (<i>R</i>² = 0.97) existed between EDCs and the total phenolic content, which confirmed that phenols contributed to the EDCs of HSs. Further analysis of molecular components confirmed that polyphenol-like compounds with medium oxygen content were the major moieties acting as electron donors in HSs. This study provides a linkage between the molecular components of HSs and their EDCs, which will help us to understand the molecular-dependent reducing properties of HSs or other dissolved organic matters under oxic conditions

Platinum Nanocrystals Embedded in Three-Dimensional Graphene for High-Performance Li–O₂ Batteries

Graphene is considered as a promising cathode candidate for Li–O2 batteries because of its excellent electronic conductivity and oxygen adsorption capacity. However, for Li–O2 batteries, the self-stacking effect caused by two-dimensional (2D) structural properties of graphene is not conducive to the rapid oxygen transport and mass transfer process, thereby affecting the electrode kinetics. Here, we successfully prepared three-dimensional (3D) graphene with different scales by plasma-enhanced chemical vapor deposition and physical pulverization strategies, in which CH4 is the carbon source and H2/Ar mixed gas is the etching gas. Meanwhile, we fabricated 3D graphene-based Pt nanocatalysts by an ultraviolet-assisted construction strategy and then applied them in Li–O2 batteries. Systematic studies reveal a special relevance between electrochemical performance and graphene particle size, and the smaller-sized 3D graphene can better maintain the microstructure distribution in both the Pt embedding process and electrochemical applications, which is beneficial to the transport of oxygen and Li ions, lowering the decomposition energy barrier of Li2O2, and further obtaining reduced charge overpotential (0.22 V) and prolonged cycle life for Li–O2 batteries. Finally, we anticipate that this work could promote the practical application of 2D materials and larger-sized 3D materials in Li–O2 batteries

GmFT2a and GmFT5a Redundantly and Differentially Regulate Flowering through Interaction with and Upregulation of the bZIP Transcription Factor GmFDL19 in Soybean

<div><p><i>FLOWERING LOCUS T</i> (<i>FT</i>) is the key flowering integrator in Arabidopsis (<i>Arabidopsis thaliana</i>), and its homologs encode florigens in many plant species regardless of their photoperiodic response. Two FT homologs, GmFT2a and GmFT5a, are involved in photoperiod-regulated flowering and coordinately control flowering in soybean. However, the molecular and genetic understanding of the roles played by GmFT2a and GmFT5a in photoperiod-regulated flowering in soybean is very limited. In this study, we demonstrated that GmFT2a and GmFT5a were able to promote early flowering in soybean by overexpressing these two genes in the soybean cultivar Williams 82 under noninductive long-day (LD) conditions. The soybean homologs of several floral identity genes, such as <i>GmAP1, GmSOC1</i> and <i>GmLFY</i>, were significantly upregulated by GmFT2a and GmFT5a in a redundant and differential pattern. A bZIP transcription factor, GmFDL19, was identified as interacting with both GmFT2a and GmFT5a, and this interaction was confirmed by yeast two-hybridization and bimolecular fluorescence complementation (BiFC). The overexpression of <i>GmFDL19</i> in soybean caused early flowering, and the transcription levels of the flowering identity genes were also upregulated by GmFDL19, as was consistent with the upregulation of GmFT2a and GmFT5a. The transcription of <i>GmFDL19</i> was also induced by GmFT2a. The results of the electrophoretic mobility shift assay (EMSA) indicated that GmFDL19 was able to bind with the cis-elements in the promoter of <i>GmAP1a.</i> Taken together, our results suggest that GmFT2a and GmFT5a redundantly and differentially control photoperiod-regulated flowering in soybean through both physical interaction with and transcriptional upregulation of the bZIP transcription factor GmFDL19, thereby inducing the expression of floral identity genes.</p></div

<i>GmFT2a</i> and <i>GmFT5a</i> promote the expression of soybean flowering-related genes.

<p>(A) Expression analyses of <i>GmFT2a</i>, <i>GmFT5a</i> and flowering-related genes in transgenic <i>GmFT2a</i> plants (#2-1-1) and wild-type Williams 82 plants (WT). (B) Expression analyses of <i>GmFT5a</i>, <i>GmFT2a</i> and flowering-related genes in transgenic <i>GmFT5a</i> plants (#5-1) and wild-type Williams 82 plants (WT). The white and black columns represent relative expression in leaves and shoot apices, respectively. Asterisks and double asterisks indicate significant differences between transgenic and WT plants at 0.01<<i>P</i><0.05 and <i>P</i><0.01, respectively.</p