The abundance of comammox bacteria was higher than that of ammonia-oxidizing archaea and bacteria in rhizosphere of emergent macrophytes in a typical shallow lake riparian.

Complete ammonia oxidation (comammox) bacteria can complete the whole nitrification process independently, which not only challenges the classical two-step nitrification theory but also updates long-held perspective of microbial ecological relationship in nitrification process. Although comammox bacteria have been found in many ecosystems in recent years, there is still a lack of research on the comammox process in rhizosphere of emergent macrophytes in lakeshore zone. Sediment samples were collected in this study from rhizosphere, far-rhizosphere, and non-rhizosphere of emergent macrophytes along the shore of Lake Liangzi, a shallow lake. The diversity of comammox bacteria and amoA gene abundance of comammox bacteria, ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) in these samples were measured. The results showed that comammox bacteria widely existed in the rhizosphere of emergent macrophytes and fell into clade A.1, clade A.2, and clade B, and clade A was the predominant community in all sampling sites. The abundance of comammox amoA gene (6.52 × 106-2.45 × 108 copies g-1 dry sediment) was higher than that of AOB amoA gene (6.58 × 104-3.58 × 106 copies g-1 dry sediment), and four orders of magnitude higher than that of AOA amoA gene (7.24 × 102-6.89 × 103 copies g-1 dry sediment), suggesting that the rhizosphere of emergent macrophytes is more favorable for the growth of comammox bacteria than that of AOB and AOA. Our study indicated that the comammox bacteria may play important roles in ammonia-oxidizing processes in all different rhizosphere regions.

Site- and Stereoselective Glycomodification of Biomolecules through Carbohydrate-Promoted Pictet-Spengler Reaction.

Carbohydrates play pivotal roles in an array of essential biological processes and are consequently involved in many diseases. To meet the needs of glycobiology research, chemical enzymatic and non-enzymatic methods have been developed to generate glycoconjugates with well-defined structures. Herein, harnessing the unique properties of C6-oxidized glycans, we report a straightforward and robust strategy for site- and stereoselective glycomodification of biomolecules with N-terminal tryptophan residues by a carbohydrate-promoted Pictet-Spengler reaction, which is not adapted to typical aldehyde substrates under biocompatible conditions. This method reliably delivers highly homogeneous glycoconjugates with stable linkages and thus has great potential for functional modulation of peptides and proteins in glycobiology research. Moreover, this reaction can be performed at the glycosites of glycopeptides, glycoproteins and living-cell surfaces in a site-specific manner. Control experiments indicated that the protected α-O atom of aldehyde donors and free N-H bond of the tryptamine motif are crucial for this reaction. Mechanistic investigations demonstrated that the reaction exhibited a first-order dependence on both tryptophan and glycan, and deprotonation/rearomatization of the pentahydro-ß-carbolinium ion intermediate might be the rate-determining step.

Progress on molecular modification and functional applications of anthocyanins.

Anthocyanins have attracted a lot of attention in the fields of natural pigments, food packaging, and functional foods due to their color, antioxidant, and nutraceutical properties. However, the poor chemical stability and low bioavailability of anthocyanins currently limit their application in the food industry. Various methods can be used to modify the structure of anthocyanins and thus improve their stability and bioavailability characteristics under food processing, storage, and gastrointestinal conditions. This paper aims to review in vitro modification methods for altering the molecular structure of anthocyanins, as well as their resulting improved properties such as color, stability, solubility, and antioxidant properties, and functional applications as pigments, sensors and functional foods. In industrial production, by mixing co-pigments with anthocyanins in food systems, the color and stability of anthocyanins can be improved by using non-covalent co-pigmentation. By acylation of fatty acids and aromatic acids with anthocyanins before incorporation into food systems, the surface activity of anthocyanins can be activated and their antioxidant and bioactivity can be improved. Various other chemical modification methods, such as methylation, glycosylation, and the formation of pyranoanthocyanins, can also be utilized to tailor the molecular properties of anthocyanins expanding their range of applications in the food industry.

Starch-guest complexes interactions: Molecular mechanisms, effects on starch and functionality.

Starch is a natural, abundant, renewable and biodegradable plant-based polymer that exhibits a variety of functional properties, including the ability to thicken or gel solutions, form films and coatings, and act as encapsulation and delivery vehicles. In this review, we first describe the structure of starch molecules and discuss the mechanisms of their interactions with guest molecules. Then, the effects of starch-guest complexes on gelatinization, retrogradation, rheology and digestion of starch are discussed. Finally, the potential applications of starch-guest complexes in the food industry are highlighted. Starch-guest complexes are formed due to physical forces, especially hydrophobic interactions between non-polar guest molecules and the hydrophobic interiors of amylose helices, as well as hydrogen bonds between some guest molecules and starch. Gelatinization, retrogradation, rheology and digestion of starch-based materials are influenced by complex formation, which has important implications for the utilization of starch as a functional and nutritional ingredient in food products. Controlling these interactions can be used to create novel starch-based food materials with specific functions, such as texture modifiers, delivery systems, edible coatings and films, fat substitutes and blood glucose modulators.

Effect of flake silver-plated copper particles on the property enhancement of electrically conductive adhesives.

To impart conductivity and improve the shear performance of epoxy resin-based adhesives, a simple, environmentally friendly, and stable method was used to deposit silver on the surface of 5 µm flake copper particles as a conductive filler. The core-shell metal fillers were prepared by utilizing the autocatalytic properties of Cu without adding any reducing agent during the reaction. An epoxy curing agent (MeTHPA) was used as a curing agent for the crosslinking reaction with epoxy resin to form a supporting skeleton of conductive components. The structure of flake plated Cu@Ag particles was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). It was verified that a layer of compact and crystalline silver with a concave-convex characteristic was deposited on the surface of copper particles. This feature has a positive effect on improving the performance of silver-plated copper particles. The results show that the optimal curing condition of flake plated Cu@Ag particle-epoxy composite electrically conductive adhesives (ECAs) was 200 °C for 1 h, the resistivity of flake plated Cu@Ag particle-epoxy composite ECAs with a content of flake plated Cu@Ag particles above 55 wt% was less than 6 × 10-5 Ω m, and the maximum shear strength was 8 MPa. The flake plated Cu@Ag particle-epoxy composite ECAs prepared by this method have excellent properties and have very important application value for advanced electronic devices.

Galectin-1 promotes angiogenesis and chondrogenesis during antler regeneration.

BACKGROUND: Deer antlers are the only known mammalian structure that undergoes full regeneration. In addition, it is peculiar because when growing, it contains vascularized cartilage. The differentiation of antler stem cells (ASCs) into chondrocytes while inducing endochondral extension of blood vessels is necessary to form antler vascularized cartilage. Therefore, antlers provide an unparalleled opportunity to investigate chondrogenesis, angiogenesis, and regenerative medicine. A study found that Galectin-1 (GAL-1), which can be used as a marker in some tumors, is highly expressed in ASCs. This intrigued us to investigate what role GAL-1 could play in antler regeneration. METHODS: We measured the expression level of GAL-1 in antler tissues and cells by immunohistochemistry, WB and QPCR. We constructed antlerogenic periosteal cells (APCs, one cell type of ASCs) with the GAL-1 gene knocked out (APCGAL-1-/-) using CRISPR-CAS9 gene editing system. The effect of GAL-1 on angiogenesis was determined by stimulating human umbilical vein endothelial cells (HUVECs) using APCGAL-1-/- conditioned medium or adding exogenous deer GAL-1 protein. The effect of APCGAL-1-/- on chondrogenic differentiation was evaluated compared with the APCs under micro-mass culture. The gene expression pattern of APCGAL-1-/- was analyzed by transcriptome sequencing. RESULTS: Immunohistochemistry revealed that GAL-1 was widely expressed in the antlerogenic periosteum (AP), pedicle periosteum (PP) and antler growth center. Western blot and qRT-PCR analysis using deer cell lines further supports this result. The proliferation, migration, and tube formation assays of human umbilical vein endothelial cells (HUVECs) showed that the proangiogenic activity of APCGAL-1-/- medium was significantly decreased (P < 0.05) compared with the APCs medium. The proangiogenic activity of deer GAL-1 protein was further confirmed by adding exogenous deer GAL-1 protein (P < 0.05). The chondrogenic differentiation ability of APCGAL-1-/- was impeded under micro-mass culture. The terms of GO and KEGG enrichment of the differentially expressed genes (DEGs) of APCGAL-1-/- showed that down-regulated expression of pathways associated with deer antler angiogenesis, osteogenesis and stem cell pluripotency, such as the PI3K-AKT signaling pathway, signaling pathways regulating pluripotency of stem cells and TGF-ß signaling pathway. CONCLUSIONS: Deer GAL-1, has strong angiogenic activity, is widely and highly expressed in deer antler. The APCs can induce angiogenesis by secreting GAL-1. The knockout of GAL-1 gene of APCs damaged its ability to induce angiogenesis and differentiate into chondrocytes. This ability is crucial to the formation of deer antler vascularized cartilage. Moreover, Deer antlers offer a unique model to explore explore how angiogenesis at high levels of GAL-1 expression can be elegantly regulated without becoming cancerous.

Community composition and abundance of complete ammonia oxidation (comammox) bacteria in the Lancang River cascade reservoir.

The construction of the reservoir has changed the nitrogen migration and transformation processes in the river, and a large amount of sediment deposition in the reservoir may also lead to the spatial differentiation of complete ammonia oxidation (comammox) bacteria. The study investigated the abundance and diversity of comammox bacteria in the sediments of three cascade reservoirs, namely, Xiaowan, Manwan, and Nuozhadu on the Lancang River in China. In these reservoirs, the average amoA gene abundance of clade A and clade B of comammox bacteria, ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) was 4.16 ± 0.85 × 105, 1.15 ± 0.33 × 105, 7.39 ± 2.31 × 104, and 3.28 ± 0.99 × 105 copies g-1, respectively. The abundance of clade A was higher than that of other ammonia oxidizing microorganisms. The spatial variation of comammox bacteria abundance differed among different reservoirs, but the spatial variation trends of the two clades of comammox bacteria in the same reservoir were similar. At each sampling point, clade A1, clade A2, and clade B coexisted, and clade A2 was usually the dominant species. The connection between comammox bacteria in the pre-dam sediments was looser than that in non-pre-dam sediments, and comammox bacteria in pre-dam sediments exhibited a simpler network structure. The main factor affecting comammox bacteria abundance was NH4+-N, while altitude, temperature, and conductivity of overlying water were the main factors affecting comammox bacteria diversity. Environmental changes caused by differences in the spatial distribution of these cascade reservoirs may be the main driver of the changes of community composition and abundance of comammox bacteria. This study confirms that the construction of cascade reservoirs results in niche spatial differentiation of comammox bacteria.

The Five-DOF Explosion-Removal Manipulator Based on Position and Velocity Feedforward Compensation Control.

The main problem with a robotic system arm is its sensitivity to time delays in the control process. Due to this problem, it is necessary to further optimize the control process of the system. One solution is to deal with the control accuracy and response speed issues of robotic arm joints, to improve the system's response performance and enhance the system's anti-interference ability. This paper proposes a speed feedforward and position control scheme for robotic arm joint control. The conclusion section shows that compared to traditional five-degree-of-freedom robotic arm systems, the addressed robotic arm control system has a lower tracking delay and better dynamic response performance. It can improve the system's response performance while also enhancing its anti-interference ability.

Research on Two-Round Self-Balancing Robot SLAM Based on the Gmapping Algorithm.

Aiming at the inconvenience of inspection and monitoring of coal mine pump room equipment in a narrow and complex environment, this paper proposes and designs a two-wheel self-balancing inspection robot based on laser SLAM. Using SolidWorks, the three-dimensional mechanical structure of the robot is designed, and the overall structure of the robot is analyzed by finite element statics. The kinematics model of the two-wheel self-balancing robot was established, and the multi-closed-loop PID controller was used to design the two-wheel self-balancing control algorithm of the robot. The 2D LiDAR-based Gmapping algorithm was used to locate the robot and construct the map. Through the self-balancing test and anti-jamming test, it is verified that the self-balancing algorithm designed in this paper has a certain anti-jamming ability and good robustness. By using Gazebo to build a simulation comparison experiment, it is verified that the selection of the particle number is of great significance for improving the map accuracy. The actual test results show that the constructed map has high accuracy.

Research on Educational Robot System Based on Vision Processing.

Aimed at the poor recognition effect of current educational robots on objects with complex shapes and colors and the single design of related experiments, this paper proposes a robot teaching instrument. The robot adopts a servo motor with an encoder, a drive, and a variety of sensors to realize a motor current loop, speed loop, position loop, and closed-loop control functions. Three experimental schemes were designed: a PID adjustment experiment, a robot obstacle avoidance and object-grasping program writing experiment, and a complex object recognition experiment based on cascade classifiers. The robot is conducive to improving students' self-initiative ability, deepening their understanding of PID closed-loop control, multi-sensor fusion, and deep learning knowledge. It can improve students' programming ability, enabling them to effectively combine theory and practice, as well as to comprehensively apply professional knowledge.

Dynamic Finite Element Model Based on Timoshenko Beam Theory for Simulating High-Speed Nonlinear Helical Springs.

Helical springs with nonlinear geometric parameters nowadays have shown great advantages over classical linear springs, especially due to their superior performance in diminishing dynamic responses in high-speed situations. However, existing studies are mostly available for springs with linear properties, and the sole FE spring models using solid elements occupy significant computational resources. This study presents an FE spring model based on Timoshenko beam theory, which allows for high-speed dynamic simulations of nonlinear springs using a beehive valve spring sample. The dynamic results are also compared with the results of the FE model using solid elements and the results of the engine head test and indicate that the proposed FE model can accurately predict dynamic spring forces and the phenomenon of coil clash when simulating the beehive spring at engine speeds of both 5600 and 8000 RPM. The results also indicate that rapid coil impact brings significant spike forces. It should also be noted that the FE spring model using beam elements displays sufficient accuracy in predicting the dynamic responses of nonlinear springs while occupying much fewer computational resources than the FE model using solid elements.

The characteristics of nitrogen and phosphorus output in China's highly urbanized Pearl River Delta region.

The nitrogen (N) and phosphorus (P) transportation due to the anthropogenic activities have strong correlations to the water pollution events. In the highly urbanized Pearl River Delta (PRD) region of China, the main input pathways for N and P have been changed. However, their main output pathways have not yet been understood. Based on the modified export coefficient model (ECM), we have quantified the N and P outputs and identified the main factors affecting the N and P outputs in highly urbanized areas such as PRD. The results showed that the N output intensity of the PRD has increased from 3010 to 3970 kg km-2·a-1 from 2008 to 2016. The P output exhibited a similar trend, from 549 to 769 kg km-2·a-1. In terms of spatial distribution, the output intensity gradually increased from economically underdeveloped regions to economically developed regions. N and P emissions in urban wastewater increased significantly with increasing urbanization rates, with output intensities increasing by 640 kg km-2·a-1 and 141 kg km-2·a-1 from 2008 to 2016, respectively. The correlation analysis showed that population density and urbanization rate were the most relevant factors with N and P outputs intensity in highly urbanized areas. This indicates that improving the effluent standards and utilization rates of wastewater treatment plants in these regions are effective measures to control N and P output. Our findings provide some new theoretical basis for the identification and management of pollution sources in highly urbanized areas for other regions, especially developing countries.

Recent advances in the application of nanotechnology to create antioxidant active food packaging materials.

Nanotechnology is being used to create innovative food packaging systems that can inhibit the oxidation of foods, thereby improving their quality, safety, and shelf life. These nano-enabled antioxidant packaging materials may therefore increase the healthiness and sustainability of the food supply chain. Recent progress in the application of nanotechnology to create antioxidant packaging materials is reviewed in this paper. The utilization of nanoparticles, nanofibers, nanocrystals, and nanoemulsions to incorporate antioxidants into these packaging materials is highlighted. The application of nano-enabled antioxidant packaging materials to preserve meat, seafood, fruit, vegetable, and other foods is then discussed. Finally, future directions and challenges in the development of this kind of active packaging material are highlighted to stimulate new areas of future research. Nanotechnology has already been used to create antioxidant packaging materials that inhibit oxidative deterioration reactions in foods, thereby prolonging their shelf life and reducing food waste. However, the safety, cost, efficacy, and scale-up of this technology still needs to be established before it will be commercially viable for many applications.

Starch as edible ink in 3D printing for food applications: a review.

Three-dimensional (3D) printing has attracted more attention in food industry because of its potential advantages, including the ability to create customized products according to individual's sensory or nutritional requirements. However, the production of high-quality 3D printed foods requires the availability of edible bio-inks with the required physicochemical and sensory attributes. Starch, as one of the important sources of dietary energy, is widely used in food processing and is considered as one kind of versatile polymers. It is not only because starch has low prices and abundant sources, but also because desirable modified starch can be obtained by altering its physicochemical properties through physical, chemical and enzymatic methods. This article focuses on the utilization of starch as materials to create food-grade bio-inks. Initially, several kinds of commonly used 3D printers are discussed. The factors affecting the printing quality of starch-based materials and improvement methods are then reviewed, as well as areas where future researches are required. The applications of 3D printed starch-based materials in food industry are also introduced. Overall, starch appears to be one kind of useful substances for creating edible bio-inks that can be utilized within 3D food printing applications to create a wide variety of food products.

SSThe coexistence and diversity of Candidatus methylomirabilis oxyfera-like and anammox bacteria in sediments of an urban eutrophic lake.

Tangxun Lake is the largest urban lake in China, which is polluted by multiple wastewaters, and now is severely eutrophic. We detected diversity, abundance, and the coexistence of Candidatus Methylomirabilis oxyfera-like and anammox bacteria in different horizontal and vertical directions of the lake sediments through qPCR and clone library. Phylogenetic tree analysis showed that the Ca. Methylomirabilis oxyfera-like and anammox bacteria exhibited high diversity, and they belonged to group B-E and Ca. Brocadia genus, respectively. These two bacteria displayed higher diversity in polluted area than in other areas. Furthermore, they had great spatial variation of abundance both horizontally and vertically. The abundance of anammox bacteria was significantly higher than that of Ca. Methylomirabilis oxyfera-like bacteria. The stronger the human interference were, the higher abundances these two bacteria exhibited horizontally, whereas both their abundances and the ratio of anammox to Ca. Methylomirabilis oxyfera-like bacteria decreased with the increasing depth. Redundancy analysis indicated that nitrate was the most influential environmental factor to the abundance of these two bacteria. Ammonia, nitrite, total nitrogen, and organic matters were in positive correlation with the abundance of these two bacteria. Nitrate was slightly negatively correlated with the abundance of Ca. Methylomirabilis oxyfera-like bacteria, while it was positively correlated with that of anammox bacteria. Our results provided an insight into the effects of environmental factors such as ammonia, nitrite, and nitrate on the diversity and abundances of these two bacteria and theoretical basis for restoration of water.

Performance improvement in monolayered SnS2 double-gate field-effect transistors via point defect engineering.

Owing to the relatively high carrier mobility and on/off current ratio, monolayered SnS2 has the advantage of suppressing drain-to-source tunneling for short channels, rendering it a promising candidate in field-effect transistor (FET) applications. To extend the scaling limit of the channel length, we propose to rationally modulate the electronic properties of monolayered SnS2 through the customized design of point defects and simulate its performance limit in sub-5 nm double-gate FETs (DGFETs), using density functional theory combined with nonequilibrium Green's function formalism. Among all types of point defects, the Se atom as a substitutional dopant (SeS) can nondegenerately inject electrons into each monolayered (ML) SnS2 2 × 4 × 1 supercell, whereas the Sn vacancy (VSn) defect exhibits an opposite doping effect. By adjusting the lateral Schottky barrier height between electrodes and the channel region, the on-state current (Ion), on/off ratio, delay time, and power-delay product in the formed n-type SeS-doped SnS2 and p-type VSn-doped SnS2 DGFETs with a channel length of 4.5 nm have been remarkably improved, fulfilling the requirements of the International Technology Roadmap for Semiconductors (ITRS) for high-performance applications in the 2028 horizon. Our work unveils the great significance of point defect engineering for applications in ultimately scaled electronics.

Research and Implementation of Autonomous Navigation for Mobile Robots Based on SLAM Algorithm under ROS.

Aiming at the problems of low mapping accuracy, slow path planning efficiency, and high radar frequency requirements in the process of mobile robot mapping and navigation in an indoor environment, this paper proposes a four-wheel drive adaptive robot positioning and navigation system based on ROS. By comparing and analyzing the mapping effects of various 2D-SLAM algorithms (Gmapping, Karto SLAM, and Hector SLAM), the Karto SLAM algorithm is used for map building. By comparing the Dijkstra algorithm with the A* algorithm, the A* algorithm is used for heuristic searches, which improves the efficiency of path planning. The DWA algorithm is used for local path planning, and real-time path planning is carried out by combining sensor data, which have a good obstacle avoidance performance. The mathematical model of four-wheel adaptive robot sliding steering was established, and the URDF model of the mobile robot was established under a ROS system. The map environment was built in Gazebo, and the simulation experiment was carried out by integrating lidar and odometer data, so as to realize the functions of mobile robot scanning mapping and autonomous obstacle avoidance navigation. The communication between the ROS system and STM32 is realized, the packaging of the ROS chassis node is completed, and the ROS chassis node has the function of receiving speed commands and feeding back odometer data and TF transformation, and the slip rate of the four-wheel robot in situ steering is successfully measured, making the chassis pose more accurate. Simulation tests and experimental verification show that the system has a high precision in environment map building and can achieve accurate navigation tasks.

Modeling, Simulation and Implementation of All Terrain Adaptive Five DOF Robot.

The ability of an off-road robot to traverse obstacles determines whether the robot can complete complex environmental tasks. In order to improve the off-road ability of off-road robots, this paper proposes a new design idea, in which four hub motors are the power system of the robot, the steering system of the robot is composed of a steering machine and a stepping motor, and a five degree of freedom robot model is established. The body structure is designed according to the characteristics of arthropods. The body structure is divided into three modules, and the connecting rod is used as the joint system of the robot to connect the three parts. The body can deform when facing complex obstacles, so as to adapt to different terrains. Then the body structure is simplified, and a mathematical model is established to describe the mathematical relationship between body joint changes. In order to verify the ability of the adaptive all-terrain cross-country robot to traverse obstacles, the load-bearing experiment and obstacle-crossing simulation experiment were carried out through Adams software, and the continuous traversing performance at low obstacles and the ability to break through high obstacles were tested, respectively. The experimental results prove that the designed adaptive all-terrain off-road robot is feasible, has good carrying capacity, and has good passability in the face of low obstacles and high obstacles. Using Ansys software to perform finite element analysis on the wheel connection, the experimental results show that the strength meets the material strength requirements. Finally, a real vehicle test is carried out to verify the correctness of the simulation results.

Design and Research of an Articulated Tracked Firefighting Robot.

Aiming to improve the situation where a firefighting robot is affected by conditions of space and complex terrain, a small four-track, four-drive articulated tracked fire-extinguishing robot is designed, which can flexibly perform fire detection and fire extinguishing tasks in a narrow space and complex terrain environment. Firstly, the overall structure of the robot is established. Secondly, the mathematical model of the robot's motion is analyzed. On this basis, the kinematics simulation is carried out by using ADAMS, and the motion of the robot is analyzed when it overcomes obstacles. Finally, the prototype was produced and tested experimentally. The robot has good obstacle-surmounting ability and excellent stability, is a reasonable size, and can perform various firefighting tasks well.

Theoretical estimation of size effects on the electronic transport in tailored graphene nanoribbons.

Focusing on the potential applications of tailored graphene nanoribbons (t-GNRs), in this work, we systematically study size effects on the electronic transport in t-GNR-based molecular junctions. As a result of the manufacturing error generated during the processing or synthesis of t-GNRs using techniques such as ion beam lithography, the final dimensions of the as-fabricated devices often deviate from the design values, giving rise to a size distribution around the mean value which could considerably affect the device performance. To simulate the effects of the manufacturing error, a series of t-GNR-based junctions with various dimensions have been modelled and systematically investigated using density functional theory (DFT) coupled with the non-equilibrium Green's function (NEGF). For junctions that consist of an acene chain connected with two graphene nanosheets, it is found that the chain length has little influence on the electronic transport and that, on the other hand, the junction conductivity is significantly altered by its width due to the different number and nature of the electron transfer pathways. Furthermore, increasing the width of the junction leads to a clear odd-even variation of decreasing amplitude in its transport behavior. These findings underpin further fundamental and device-based studies of t-GNRs.