Summary
In this paper, an adaptive observer based output feedback prescribed‐time control is designed for a class of nonlinear systems with unknown parameters. According to the characteristics of the ...nonlinear systems, a novel adaptive observer is first designed. Then by imposing parametric Lyapunov equations, a time‐varying high‐gain observer based output feedback adaptive controller is constructed, by which, it is proven that the states of both the observer and the original system can be driven to zero within any prescribed time. Moreover, the control signal is proven uniformly bounded by a scalar. Two numerical examples are illustrated to verify the effectiveness of the proposed method.
In this article, a novel Lyapunov-based approach for strong prescribed-time stabilization by periodic delayed feedback is established. Since the comparison lemma cannot be directly applied to ...time-delay systems, their proofs rely on trajectory analysis. Based on this approach, a novel control law for strong prescribed-time stabilization of uncertain scalar nonlinear systems is obtained, with the following appealing properties: singularity problems inherent to time-varying high gain approaches are avoided; strong prescribed-time stabilization is achieved with control terms exhibiting a linear growth rate in the combined current and delayed state variable; the achieved fixed-time stability is preserved under classes of additive perturbations; and the setting time of the closed-loop system equals the prescribed value for some admissible uncertainties. Subsequently, using the backstepping procedure, a strongly prescribed-time stabilizing control law for strict feedback uncertain nonlinear systems is designed. Numerical simulations are shown to verify the effectiveness of the proposed approaches.
Paclitaxel (PTX) is among the most commonly used first-line drugs for cancer chemotherapy. However, its poor water solubility and indiscriminate distribution in normal tissues remain clinical ...challenges. Here we design and synthesize a highly water-soluble nucleolin aptamer-paclitaxel conjugate (NucA-PTX) that selectively delivers PTX to the tumor site. By connecting a tumor-targeting nucleolin aptamer (NucA) to the active hydroxyl group at 2' position of PTX via a cathepsin B sensitive dipeptide bond, NucA-PTX remains stable and inactive in the circulation. NucA facilitates the uptake of the conjugated PTX specifically in tumor cells. Once inside cells, the dipeptide bond linker of NucA-PTX is cleaved by cathepsin B and then the conjugated PTX is released for action. The NucA modification assists the selective accumulation of the conjugated PTX in ovarian tumor tissue rather than normal tissues, and subsequently resulting in notably improved antitumor activity and reduced toxicity.
This article studies the problem of finite-time, fixed-time, and prescribed-time stability analysis and stabilization. First, a linear time-varying (LTV) inequality-based approach is introduced for ...prescribed-time stability analysis. Then, it is shown that the existing nonlinear Lyapunov inequalities-based finite- and fixed-time stability criteria can be recast into the unified framework of the LTV inequality-based approach for prescribed-time stability. Finally, the unified LTV inequality-based approach is used to solve the global prescribed-time stabilization problem of the attitude control system of a rigid spacecraft with disturbance, and a bounded nonlinear time-varying controller is proposed via back stepping. Numerical simulations are presented to show the effectiveness of the proposed methods.
To engineer patient‐derived cells into therapy‐purposed biologics is a promising solution to realize personalized treatments. Without using gene‐editing technology, a live cell‐typed therapeutic is ...engineered for tumor treatment by artificially reprogramming macrophages with hyaluronic acid‐decorated superparamagnetic iron oxide nanoparticles (HIONs). This nanoparticle‐assisted cell‐reprogramming strategy demonstrates profound advantages, due to the combined contributions from the biological regulation of HIONs and the intrinsic nature of macrophages. Firstly, the reprogrammed macrophages present a substantial improvement in their innate capabilities, such as more effective tumor targeting and more efficient generation of bioactive components (e.g., reactive oxygen species, bioactive cytokines) to suppress tumor growth. Furthermore, this cell therapeutic exhibits cytostatic/proapoptotic effects specific to cancer cells. Secondly, HIONs enable macrophages more resistant to the intratumoral immunosuppressive environment. Thirdly, the macrophages are endowed with a strong ability to prime in situ protumoral M2 macrophages into antitumor M1 phenotype in a paracrine‐like manner. Consequently, a synergistic tumor‐inhibition effect is achieved. This study shows that engineering nanomaterial‐reprogrammed live cells as therapeutic biologics may be a more preferable option to the commonly used approaches where nanomaterials are administrated to induce bioresponse of certain cells in vivo.
A live cell‐typed therapeutic is engineered for tumor treatment by reprogramming macrophages with HION nanoparticles. The advantage of this ex vivo cell‐reprogramming strategy is evidenced by cancer‐cell‐specific toxicity, more efficient production of bioactive components, stronger resistance against intratumoral immunosuppression, and favorable ability to prime in situ protumoral M2 macrophages into antitumor M1 phenotype in a paracrine‐like manner.
This article studies the prescribed‐time stabilization problem of p‐normal nonlinear systems by bounded time‐varying high‐gain feedback. A time‐varying bounded controller, which can achieve ...prescribed‐time stabilization, is designed via backstepping. Because of the usage of time‐varying high‐gain functions which grow unbounded as the time tends to the prescribed time, the usual separation technique is invalid. To solve this problem, a novel design scheme is proposed. It is shown that all of the closed‐loop trajectories convergence to the origin in prescribed time. Finally, a numerical example verifies the effectiveness of the proposed method.
Ionic liquids (ILs) have many attractive properties. For example, their physical and chemical properties can be tuned by a judicious design of the cations and anions, making them ideal candidates for ...designable building blocks of stimuli‐responsive materials. Numerous IL‐based stimuli‐responsive materials have been developed by chemical modification (covalent, coordination, or ionic functionalization) or physical blending of ILs with other functional materials. The flexible tunability of ILs provides a great opportunity to achieve the desired physicochemical properties for task‐specific applications, such as sensing, display, gas capture, and so on. This review aims to address the recent advances in IL‐based stimuli‐responsive materials, which are categorized by the type of external stimuli, including gas‐responsive, organic solvent‐responsive, ion‐responsive, pH‐responsive, thermo‐responsive, photo‐responsive, and electro‐responsive materials.
The attractive properties of ionic liquids make them ideal candidates for designable building blocks of stimuli‐responsive materials. This review aims to address the recent advances in ionic liquid‐based stimuli‐responsive materials and they are categorized by the type of external stimuli, including gas‐responsive, organic solvent‐responsive, ion‐responsive, pH‐responsive, thermo‐responsive, photo‐responsive, and electro‐responsive materials.
This paper studies the prescribed-time control problem of nonholonomic systems. By using some properties of a class of parametric Lyapunov equations and constructing time-varying Lyapunov-like ...functions, a time-varying high-gain feedback controller is firstly proposed for the chained nonholonomic system such that the state of the closed-loop system converges to zero at any prescribed time. The advantage of time-varying feedback is revealed by comparison with time-invariant feedback. Then time-varying high-gain feedback controllers for a class of perturbed nonholonomic systems are designed to achieve prescribed time convergence of the states. Both state feedback and observer-based output feedback are considered and the controls are proved to be bounded in all the cases. The effectiveness of the proposed methods are verified by numerical examples.
Extreme hypoxia of tumors represents the most notable barrier against the advance of tumor treatments. Inspired by the biological nature of red blood cells (RBCs) as the primary oxygen supplier in ...mammals, an aggressive man‐made RBC (AmmRBC) is created to combat the hypoxia‐mediated resistance of tumors to photodynamic therapy (PDT). Specifically, the complex formed between hemoglobin and enzyme‐mimicking polydopamine, and polydopamine‐carried photosensitizer is encapsulated inside the biovesicle that is engineered from the recombined RBC membranes. The mean corpuscular hemoglobin of AmmRBCs reaches about tenfold as high as that of natural RBCs. Owing to the same origin of outer membranes, AmmRBCs share excellent biocompatibility with parent RBCs. The introduced polydopamine plays the role of the antioxidative enzymes existing inside RBCs to effectively prevent the oxygen‐carrying hemoglobin from the oxidation damage during the circulation. This biomimetic engineering can accumulate in tumors, permit in situ efficient oxygen supply, and impose strong PDT efficacy toward the extremely hypoxic tumor with complete tumor elimination. The man‐made pseudo‐RBC shows potentials as a universal oxygen‐self‐supplied platform to sensitize hypoxia‐limited tumor treatment means, including but not limited to PDT. Meanwhile, this study offers ideas to the production of artificial substitutes of packed RBCs for clinical blood transfusion.
Aggressive man‐made pseudo‐red blood cells (AmmRBCs) are prepared for self‐oxygen‐supplied photodynamic therapy (PDT) toward tumors. AmmRBCs can accumulate in tumors and exhibit high efficacy to combat hypoxia‐induced resistance of tumors to PDT, leading to complete tumor elimination.
This paper studies the prescribed-time input-to-state stabilization problem of normal nonlinear systems. With the help of some key properties of a class of parametric Lyapunov equations, the ...prescribed-time input-to-state stabilization problem of normal nonlinear systems under matched uncertainties is studied. Some bounded time-varying controllers are proposed. It is shown that the closed-loop systems are prescribed-time input-to-state stable. Finally, the effectiveness of the established methods is illustrated by two physical systems.
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