One of the simplest ways to prepare liposomes in a research laboratory is the thin-film hydration method followed by extrusion. This method involves making a thin lipid film in a round-bottom flask ...by the removal of organic solvent. Upon the addition and agitation of the dispersion medium, heterogeneous liposomes are formed. Finally, after extrusion through polycarbonate membranes, homogeneous small liposomes are obtained.
A practical design method is developed for cooperative tracking control of higher-order nonlinear systems with a dynamic leader. The communication network is a weighted directed graph with a fixed ...topology. Each follower node is modeled by a higher-order integrator incorporating with unknown nonlinear dynamics and an unknown disturbance. The leader node is modeled as a higher-order nonautonomous nonlinear system. It acts as a command generator giving commands only to a small portion of the networked group. A robust adaptive neural network controller is designed for each follower node such that all follower nodes ultimately synchronize to the leader node with bounded residual errors. Moreover, these controllers are distributed in the sense that the controller design for each follower node only requires relative state information between itself and its neighbors. A simulation example demonstrates the effectiveness of the algorithm.
Cohort studies play an important role in elucidating the association between risk factors and diseases， and are widely used in etiology research， the assessment of disease prognosis， understanding ...the natural history of diseases， and the surveillance following the market release of new drugs. The data produced by cohort studies possess great scientific value and can provide essential evidence for public health practice. A well-conceived scientific design is a prerequisite to conducting a cohort study， and the design should focus on aspects such as sample size， selection of exposed and non-exposed populations， follow-up procedures， outcome assessments， research duration， and the choice of analytical indicators and methods. Cohort studies have become an important way to obtain scientific evidence. Internationally renowned population-based cohorts， such as China Kadoorie biobank and the Framingham heart study cohort， have provided a wealth of scientifically valuable evidence for promoting human health. The quali
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tersely and concisely reviews the recent development of the polymer electrolyte membranes and the relationship between their properties and affecting factors like operation ...temperature. In the first section, the advantages and shortcomings of the corresponding polymer electrolyte membrane fuel cells are analyzed. Then, the limitations of Nafion membranes and their alternatives to large-scale commercial applications are discussed. Secondly, the concepts and approaches of the alternative proton exchange membranes for low temperature and high temperature fuel cells are described. The highlights of the current scientific achievements are given for various aspects of approaches. Thirdly, the progress of anion exchange membranes is presented. Finally, the perspectives of future trends on polymer electrolyte membranes for different applications are commented on (400 references).
This article reviews the up-to-date advances in the polymer electrolyte membranes, especially for the proton exchange membranes, used for fuel cells.
This paper addresses the leader-follower synchronization problem of uncertain dynamical multiagent systems with nonlinear dynamics. Distributed adaptive synchronization controllers are proposed based ...on the state information of neighboring agents. The control design is developed for both undirected and directed communication topologies without requiring the accurate model of each agent. This result is further extended to the output feedback case where a neighborhood observer is proposed based on relative output information of neighboring agents. Then, distributed observer-based synchronization controllers are derived and a parameter-dependent Riccati inequality is employed to prove the stability. This design has a favorable decouple property between the observer and the controller designs for nonlinear multiagent systems. For both cases, the developed controllers guarantee that the state of each agent synchronizes to that of the leader with bounded residual errors. Two illustrative examples validate the efficacy of the proposed methods.
A yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The void space is engineered to fit the volume expansion of Sn during cycling. It is ...demonstrated that the shell thickness of carbon nanobox has substantial influence on both nanostructures and the electrochemical performance. With an optimized shell thickness, a high reversible capacity of 810 mA h g−1 can be maintained after 500 cycles, corresponding to 90% retention of the second discharge capacity. For Sn@C materials with either thinner or thicker carbon shells, significant capacity decay or a decreased specific capacity are observed during cycling. The present study sheds light on the rational design of nanostructured electrode materials with enhanced electrochemical performance for next‐generation lithium ion batteries.
A novel yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The generation of metallic Sn together with the void space and the conversion of polymer to carbon are simultaneously completed in one step. Importantly, with an optimized carbon shell thickness, the composite exhibits high specific capacity, good rate performance, and exceptional cycling stability.
Due to the urgent requirement to achieve secure communication between service providers (SPs) and smart meters (SMs), including reliable mutual authentication and privacy credentials, key management ...is critical in smart grids. Recently, a number of key management schemes have been proposed. However, schemes based on trusted third parties (TTPs) become insecure if the TTP fails. Furthermore, the SPs in most schemes are centralized to manage their respective SMs, which involve a single point of failure. Furthermore, SPs cannot monitor each other for data traceability or security auditing. To remedy these inadequacies, we propose a decentralized keyless signature scheme based on a consortium blockchain to realize more efficient and secure key management. The SM sends requests and receive responses using a blockchain network for data transmission operations. We designed a decentralized secure consensus mechanism that turns a blockchain into an automated access-control manager that does not require a TTP or trust anchor. The SPs of the proposed scheme can keep each other in check using the blockchain. In our concluding remarks, we describe how the proposed scheme incurs smaller computational time costs and is both cost-effective and scalable.
The copper‐catalyzed radical aminofluorination of styrenes with N‐fluorobenzenesulfonimide (NFSI) is realized with high regioselectivity, thus affording aminofluorination products with ...regioselectivities opposite that of the palladium‐catalyzed and noncatalyzed processes. Preliminary mechanistic studies suggested the reaction went through a radical pathway and was supported by DFT calculations. In these reactions, NFSI is utilized as both a radical nitrogen source and radical fluorine source, thus rendering it an attractive reagent.
Double agent: The copper‐catalyzed radical aminofluorination of styrenes with N‐fluorobenzenesulfonimide (NFSI) has been realized with high regioselectivity, thus affording aminofluorination products with regioselectivities opposite to those of the palladium‐catalyzed and noncatalyzed processes. NFSI reacts under NF bond homolysis and is utilized as both a radical nitrogen source and radical fluorine source.
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