Search

cis‐Prenyltransferases (cis‐PTs) catalyze the sequential head‐to‐tail condensation of isopentenyl diphosphate (IPP) to allylic diphosphates, producing mixed E–Z prenyl diphosphates of varying lengths; however, the specific enzymes synthesizing cis‐C25 prenyl diphosphates have not been identified. Herein, we present the discovery and characterization of a cis‐geranylfarnesyl diphosphate synthase (ScGFPPS) from Streptomyces clavuligerus. This enzyme demonstrates high catalytic proficiency in generating six distinct cis‐polyisoprenoids, including three C25 and three C20 variants. We determined the crystal structure of ScGFPPS. Additionally, we unveil the crystal structure of nerylneryl diphosphate synthase (NNPS), known for synthesizing an all‐cis‐C20 polyisoprenoid. Comparative structural analysis of ScGFPPS and NNPS has identified key differences that influence product specificity. Through site‐directed mutagenesis, we have identified eight single mutations that significantly refine the selectivity of ScGFPPS for cis‐polyisoprenoids. Our findings not only expand the functional spectrum of cis‐PTs but also provide a structural comparison strategy in cis‐PTs engineering. [ABSTRACT FROM AUTHOR]

This article investigates distributed optimization of high‐order nonlinear multi‐agent systems (MASs) with disturbance under switching topologies. First, we propose a class of new distributed control algorithms for high‐order MASs under switching topologies, such that all agents asymptotically reach consensus at the unique minimizer of the sum of cost functions. Then, by constructing disturbance observer, the proposed algorithms are extended to address distributed optimization problems for high‐order nonlinear MASs with disturbance under switching topologies. In particular, both of new presented methods do not require optimal reference signal generator, which can save the computational resources of systems. In final, simulations are conducted to validate the theoretical results. [ABSTRACT FROM AUTHOR]

This article proposes a new distributed finite‐time optimization algorithm for agents under directed graphs. By employing the nonsmooth technique and graph theory, a distributed discontinuous algorithm for continuous‐time agents subject to strongly convex local cost functions is first designed with a finite‐time distributed estimator, where the gradients of the local cost functions are estimated in finite time. It is shown that for a strongly connected graph and arbitrary initial conditions, the proposed algorithms can achieve consensus, and the systems can converge to the optimal point in finite time. Then, a two‐step approach is proposed to achieve finite‐time optimization of high‐order agents with disturbances under directed graphs. Finally, the validity of the proposed finite‐time optimization algorithm is verified by two numerical examples. [ABSTRACT FROM AUTHOR]

Existing distributed finite‐time optimization algorithms for continuous‐time multi‐agent systems require either undirected graphs or weight balanced digraphs, and distributed finite‐time optimization problems for weight unbalanced digraphs are still great challenging. Thus, the distributed finite‐time optimization problems for continuous‐time multi‐agent systems with strongly convex local cost functions are investigated under directed graphs in this article. First, a distributed finite‐time gradient estimator is constructed by using non‐smooth analysis and algebraic graph theory, then distributed finite‐time optimization algorithms and piecewise distributed finite‐time optimization algorithms are proposed based on the designed gradient estimator. The new proposed distributed finite‐time optimization algorithms which only require strongly connected graphs relax the balanced requirement. Furthermore, the communication bandwidth of systems could be saved by deploying the proposed piecewise distributed finite‐time optimization algorithms since the information exchange in the optimization process is reduced. Finally, simulation examples are given to verify the effectiveness of proposed distributed optimization algorithms. [ABSTRACT FROM AUTHOR]

BACKGROUND Heat‐induced composite gels were prepared with 20 g kg−1 myofibrillar protein (MP) sol, 20 g kg−1 modified starch and 100 g kg−1 lipid pre‐emulsified by MP in 0.6 mol L−1 NaCl, at pH 6.2. The effects of esterified potato starch (EPS) and emulsified lipid (lard or peanut oil) on the rheology, texture properties and nuclear magnetic resonance characterization of MP gel were evaluated. RESULTS: The addition of starch and lipid significantly improved the gel strength and water holding capacity (WHC) of the MP gel. Analysis of the relaxation time compared with the WHC tests showed that the variation range of the transverse T22 relaxation time of a gel was positively proportional to changes in WHC of the composite gel, and the lower the T22 relaxation time, the better the WHC of composite gel. Moreover, MP gel with starch and emulsified lard added at the same time has the lowest T2 relaxation time, and also the best WHC of the gel. Environmental scanning electron microscopy showed that emulsified oil droplets embedded the gaps in the protein network, and the gelatinized starch contributed to restrict the oil droplet size, resulting in thicker MP gel. CONCLUSION: Emulsified lipid and modified starch have an important influence on the rheology and microstructure of MP gels, indicating the subtle interaction between starch, lipid and protein. The results suggest the potential feasibility of modified starch and vegetable oil to improve the textural properties in comminuted meat products. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This paper investigates the formation control of connected autonomous vehicle (CAV) platoons moving in multi lanes using distance‐based formation control techniques based on rigid graphs and V2V communication. A hierarchical architecture is proposed to decompose the cooperative control into velocity planning and vehicle dynamic control. A new velocity planning method is first developed via a distributed distance‐based formation controller so that each vehicle can keep platoon and change lane. Then, for the vehicle dynamics with nonlinearities and bounded disturbances, an adaptive controller is designed for regulating driving/braking torque to achieve the longitudinal velocity output of the velocity planner. The steering controller is designed to adjust the yaw angle of each vehicle to track and change lanes. Furthermore, stability analysis is conducted based on the Lyapunov theory. Finally, the applications of the proposed control designs to various of automated highway system (AHS) scenarios including lane‐change, curve lane and platoon overtaking, are simulated and numerically analysed to validate the effectiveness of theoretical results. [ABSTRACT FROM AUTHOR]

In this article, we explore the possibility of designing a continuous control algorithm for time‐varying networks of high‐order nonlinear agents with input saturation. A class of neural network‐based (NN) distributed control algorithms are proposed for the consensus of nonlinear agents with input saturation and nonidentical unknown control directions (UCDs) under uniformly quasi‐strongly δ‐connected graphs. An NN is used to cancel the unknown part of agent dynamics due to the well known NN function approximation property. Also, an adaptive smooth term is employed to compensate for the bounded disturbance, the approximation error. Moreover, an auxiliary system is designed to counteract the effect of input saturation. Furthermore, the control law is augmented with the Nussbaum‐type function to obtain an estimation of the UCDs. It is proven rigorously that the consensus of nonlinear agents with input saturation and nonidentical UCDs can be guaranteed, and the boundedness of all signals of closed‐loop systems is ensured. Finally, simulation examples are given to show the effectiveness of our theoretical results. [ABSTRACT FROM AUTHOR]

This paper studies the optimal consensus problem of high‐order nonlinear agents under digraphs by PI regulation. A new type of adaptive PI variables is proposed for the first time, which is independent of the global information of graphs and complex dynamics. With the proposed variables, a key lemma is derived to transform the optimal consensus problem into a regulation problem, such that classical control techniques are used to regulate the adaptive PI variables for more complex dynamics. We also develop a new kind of distributed control algorithms based on the adaptive PI variables, Nussbaum‐type functions, and neural networks (NN). The proposed algorithms achieve the optimal consensus for high‐order nonlinear agents with nonidentical unknown control directions, bounded disturbances, and input saturation over weight‐unbalanced directed networks. Finally, a simulation example is provided to illustrate the effectiveness of the proposed algorithms. [ABSTRACT FROM AUTHOR]

PD‐1 is a highly glycosylated inhibitory receptor expressed mainly on T cells. Targeting of PD‐1 with monoclonal antibodies (MAbs) to block the interaction with its ligand PD‐L1 has been successful for the treatment of multiple tumors. However, polymorphisms at N‐glycosylation sites of PD‐1 exist in the human population that might affect antibody binding, and dysregulated glycosylation has been observed in the tumor microenvironment. Here, we demonstrate varied N‐glycan composition in PD‐1, and show that the binding affinity of camrelizumab, a recently approved PD‐1‐specific MAb, to non‐glycosylated PD‐1 proteins from E. coli is substantially decreased compared with glycosylated PD‐1. The structure of the camrelizumab/PD‐1 complex reveals that camrelizumab mainly utilizes its heavy chain to bind to PD‐1, while the light chain sterically inhibits the binding of PD‐L1 to PD‐1. Glycosylation of asparagine 58 (N58) promotes the interaction with camrelizumab, while the efficiency of camrelizumab to inhibit the binding of PD‐L1 is substantially reduced for glycosylation‐deficient PD‐1. These results increase our understanding of how glycosylation affects the activity of PD‐1‐specific MAbs during immune checkpoint therapy. Synopsis: PD‐1 is a highly glycosylated receptor with a varied N‐glycan composition. The therapeutic antibody camrelizumab binds to the N58 glycan of PD‐1 and absent glycosylation results in decreased binding affinity and PD‐1/PD‐L1 blocking efficiency. PD‐1 shows a varied N‐glycan composition and glycosylation of PD‐1 is critical for PD‐1 stability.N58 glycosylation of PD‐1 promotes the interaction and contributes to the high binding affinity of camrelizumab.The efficiency of camrelizumab to inhibit the binding of PD‐L1 to N58 glycosylation‐deficient PD‐1 is substantially reduced. [ABSTRACT FROM AUTHOR]

To determine antimicrobial resistance, 431 samples of retail foods purchased at different supermarkets in Northern Xinjiang were examined in this study. There were 112 Escherichia coli strains that were isolated, with approximately 26% of the samples contaminated by E. coli. The detection rate of E. coli isolated from pork was the highest (59.6%), followed by mutton (52.6%), retail fresh milk (52.4%), duck (36.4%), beef (35.3%), chicken (33.3%), and ready‐to‐eat food (12.9%); the E. coli detection rate for fish and vegetables was <11%. The result showed that the 112 isolates were mostly resistant to tetracycline (52%), followed by ampicillin (42%), compound trimethoprim/sulfamethoxazole (37%), amoxicillin (33%), and nalidixic acid (32%), imipenem resistance was not detected. One hundred isolates carried at least one antimicrobial resistance gene. The detection rate of resistance genes of our study was as follows: tetA (38%), tetB (27%), blaOXA (40%), blaTEM (20%), floR (20%), sul1 (16%), sul2 (27%), aadAla (19%), aadB (11%), strA (28%), and strB (24%); tetC and blaPSE were not detected. Virulence genes fimC, agg, stx2, fimA, fyuA, papA, stx1, and eaeA were found in 52, 34, 21, 19, 6, 3, 2, and 2 isolates, respectively; papC was not detected. There was a statistically significant association between fimC and resistance to ciprofloxacin (p =.001), gentamicin (p =.001), amikacin (p =.001), levofloxacin (p =.001), and streptomycin (p =.001); between fimA and resistance to tetracycline (p =.001), ampicillin (p =.001), compound trimethoprim/sulfamethoxazole (p =.001), and amoxicillin (p =.003); between agg and resistance to gentamicin (p =.001), tetracycline (p =.001), ciprofloxacin (p =.017), and levofloxacin (p =.001); and between stx2 and resistance to ampicillin (p =.001), tetracycline (p =.001), compound trimethoprim/sulfamethoxazole (p =.002), and amoxicillin (p =.015). [ABSTRACT FROM AUTHOR]

The increasing demand for plant proteins, along with rising awareness of the nutritional and functional roles of dietary proteins, has prompted the nutrition and food industry to explore nontraditional protein sources. Hempseed protein with its excellent nutritional value and superior digestibility has drawn great interest in both scientific and industrial fields. In this review, the chemistry and nutritional quality of hempseed protein and the health benefits of bioactive peptides derived thereof are highlighted. Processing, functionality, and application of various hemp protein products, including hempseed meal, hemp protein concentrates, and hemp protein isolates, are discussed. Moreover, recent advances in technological innovation to improve hempseed protein functionality are introduced. The objective of this review is to provide an updated summary of the research on hempseed protein and to fill the knowledge gap in the exploitation of potential nutritional, health, and processing benefits of this emerging protein source. [ABSTRACT FROM AUTHOR]

A self‐triggered model predictive control (MPC) scheme for continuous‐time perturbed nonlinear systems subject to bounded disturbances is investigated in this study. A self‐triggered strategy is designed to obtain the inter‐execution time before the next trigger using the current sampled state. An optimisation problem is addressed to obtain the optimal control trajectory at each triggered instant. The so‐called dual‐mode approach is used to stabilise the perturbed closed‐loop system. Furthermore, sufficient conditions are derived to ensure the feasibility and stability, respectively. It is shown that with a properly designed prediction horizon, the feasibility of the proposed self‐triggered MPC algorithm can be guaranteed if the disturbance is bounded in a small enough area. Meanwhile, the stability is proved under the self‐triggered condition. Finally, a numerical example is given to illustrate the efficacy of the authors proposed scheme. [ABSTRACT FROM AUTHOR]

Summary: Tail‐sitter unmanned aerial vehicles (UAVs) can flight as rotorcrafts as well as fixed‐wing aircrafts, but it is hard to control the flight mode transition. The vehicle dynamics involves serious parametric uncertainties, highly nonlinear dynamics, and is easy to be affected by external disturbances, especially during the mode transition. This paper presents a robust control method for a kind of tail‐sitter UAVs to achieve the flight mode transition. The robust controller is proposed based on the state‐feedback control scheme and the robust compensation method. The proposed control method does not need to switch the coordinate system, the controller structure, or the controller parameters during the mode transitions. Theoretical analysis is given to guarantee the robustness stability of the designed flight control system. Numerical simulation results are presented to show the advantages of the proposed control method compared with the state‐feedback control method and the sliding mode control approach. [ABSTRACT FROM AUTHOR]

Summary: This study assessed the effect of ferulic acid on the accumulation of histamine in traditional Xinjiang smoked horsemeat sausage. The dynamics of histamine‐producing microorganisms were monitored by PCR‐denaturing gradient gel electrophoresis (DGGE) with specific primer pairs, and histidine and histamine levels were measured by high‐performance liquid chromatography (HPLC). Relative parameters including microbiological growth, pH and moisture content were also evaluated. PCR‐DGGE provided a rapid and convenient method for detecting and identifying histamine‐producing bacteria. The results showed that ferulic acid reduced the histamine concentration and inhibited the growth of histamine‐producing bacteria during fermentation and ripening. Additionally, the inhibitory effect of ferulic acid was stronger than that of the starter culture. Therefore, ferulic acid appears to be a useful additive for manufacturing fermented sausages. [ABSTRACT FROM AUTHOR]

The problem of robust global consensus tracking of linear multiagent systems with input saturation and input-additive uncertainties is investigated in this paper. By using the parametric Lyapunov equation approach and an existing dynamic gain scheduling technique, a new distributed nonlinear-gain scheduling consensus-trackining algorithm is developed to solve this problem. Under the assumption that each agent is asymptotically null controllable with bounded control, it is shown that the robust global consensus tracking can be achieved under the undirected graph provided that its generated graph contains a directed spanning tree. Compared with the existing algebraic Riccati equation approach, which requires the online solution of a parameterized algebraic Riccati equation, all the parameters in the proposed nonlinear algorithm are offline determined a priori. Finally, numerical examples are provided to validate the theoretical results. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper solves the robust output synchronization problem for a group of linear agents subject to constant disturbances on directed graphs. A new distributed control protocol with integral action is first proposed with the assumption that each agent has access to its own state. Then, an observer-based implementation of the control protocol is illustrated for the case that the agents do not have access to their states. Compared with existing methods, the new distributed protocol does not require exchanging of the controller states or output states among neighboring agents. Finally, simulation results of a group of low-speed experimental unmanned aerial vehicles show the effectiveness of the proposed methods. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper proposes a new class of nonlinear protocols for fixed-time consensus in networked agents with directed and intermittent communications. First of all, based on the assumption of a common positive dwell time for all successful links, it is theoretically shown that the asymptotical consensus can be achieved if the interaction topology with some fixed length of time has a spanning tree. Then, if the length sum of time intervals, over which the directed interaction topology contains a spanning tree, is larger that a threshold value, which is independent of initial conditions, the system will solve a fixed-time consensus problem. Furthermore, in light of the mirror operation principle of graph theory, the proposed protocol is extended to solve the fixed-time consensus problem if a common positive dwell time for all active links is strongly connected without the detailed balanced condition. Finally, the effectiveness of the theoretical results is illustrated by simulation results. [ABSTRACT FROM AUTHOR]

This study addresses the consensus problem for single‐integrator agents with heterogeneous output saturation. By investigating the unique achievable equilibrium and employing an integral Lyapunov function, some conditions of single‐integrator agents with heterogeneous and magnitude output saturation are presented. The main contribution of this work is that under the directed graph with strongly connected or a spanning tree, a necessary and sufficient condition for consensus with heterogeneous and magnitude output saturation is first obtained. In addition, some properties of the unachievable consensus are discussed. Finally, simulation examples are given to show the validity of the theoretical results. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of semiglobal stabilization with guaranteed flexible pole placement for saturated linear systems. To retain the advantages of the parametric Lyapunov equation, matrix-partitioning idea is used to derive a new pole shift lemma. Starting from system matrix transformations, a recursive algorithm is proposed to shift every eigenvalue of a linear system separately without mode decomposition in each step. A new method introducing various parameters to every Lyapunov equation in each step is presented. As an application, the semiglobal stabilization with guaranteed flexible pole placement for saturated linear systems can be achieved by this method. Finally, its effectiveness and advantages are demonstrated via a simulation example. [ABSTRACT FROM AUTHOR]

This paper investigates the semiglobal synchronization problem for a group of agents with input saturation under directed interaction topology, where each agent is modeled as a generic linear system rather than the single-integrator or double-integrator dynamics. The main result is the construction of a feedback coupling gain that achieves semiglobal synchronization if all the agents have identically saturated linear dynamics, which can be of any order. It is shown that the coupling gain obtained via parametric Lyapunov equations can semiglobally synchronize any directed network provided that the interaction topology has a directed spanning tree. Furthermore, due to the use of parametric Lyapunov equations, a convergence rate is analytically obtained. Finally, a simulation example is provided to demonstrate the effectiveness and advantages of our theoretical findings. [ABSTRACT FROM AUTHOR]

Fatty acid profiles and volatile composition in the yolks of conventional eggs from seven different species (duck, free-range chicken, silky chicken, quail, pigeon, goose, and chicken) were compared using GC-MS and electronic nose (E-nose). The results showed that there were significant differences among the fatty acid profiles of the seven avian eggs. Goose eggs contained the highest contents of saturated and monounsaturated fatty acids but the lowest content of polyunsaturated fatty acids (PUFA), and the differences were significant ( p<0.05). The PUFA proportion was the highest in the free-range chicken eggs of all the tested avian eggs. The ω-3 PUFA content and the ω-6/ω-3 ratio were significantly ( p<0.05) higher in the yolks of goose and silky chicken. The volatile compositions of egg yolks are esters, alcohols, alkenes, and nitrogenous compounds, and the major compounds that contributed to discrimination of different species of eggs were ethyl acetate, pathalic acid butyl isohexyl ester, O-methylisourea hydrogen sulfate, 1-butanol, and N-isopropylbenzamide. In addition, seven different species of eggs were distinguished from each other through principal component analysis of E-nose data, suggesting that the E-nose may be a potential technology for discriminating different species of eggs. Practical applications: The results showed that the major volatile components could be used as chemical markers to distinguish different species of eggs by the chemometric method. The results obtained from the electronic nose analysis agreed well with the GC-MS results, suggesting the potential application of the E-nose technique in the market quality control and the detection of counterfeit eggs. Twenty-two fatty acids were detected and significant differences were found in the fatty acid proportions of different poultry eggs. A total of 41 volatiles were identified by GC-MS, and E-nose can successfully discrimination different species of eggs. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of leader‐following consensus of single‐integrator agents subject to saturation constraints. Global leader‐following consensus protocol is developed with proper choice of the relative coupling gain. Both the case of input saturation and the case of actuator saturation are considered. It is shown that global consensus of the multiagent system can be reached under the general undirected graph provided that its augmented graph contains a directed spanning tree. Numerical examples are provided to demonstrate the theoretical results. [ABSTRACT FROM AUTHOR]

Abstract: The great shortage of human hepatic cells makes it desirable to generate extrahepatic stem or precursor cells. In recent years, it has been reported that human multipotential mesenchymal stem cells (hMSCs) differentiate into hepatocyte-like cells. The fetal lung is one of the largest organs containing many MSCs that can be easily obtained. Whether MSCs from fetal lung can differentiate into hepatocytes or bile duct cells is an important issue in basic medicine and clinical application. We isolated fetal lung cells, and expanded and analyzed them. At passage 4, their morphologic, immunophenotyping and cytokine secretions were similar to adult bone marrow-derived MSCs. We conclude that these cells from fetal lung are MSCs, indicating that human fetal lung is an ideal source of hMSCs. hMSCs from fetal lung induced in special differentiation medium showed homogeneous and small polygonal endothelial-like morphology, expressing weak mRNA, as well as Alb and AFP. This implies that hMSCs from fetal lung can differentiate into hepatocyte-like cells. [Copyright &y& Elsevier]