In recent years, owing to unsatisfactory clinical imaging clarity and depths in the living body for early diagnosis and prognosis, novel imaging modalities with high bioimaging performance have been ...actively explored. The remarkable headway made in the second near-infrared region (NIR-II, 1000-1700 nm) has promoted the development of biomedical imaging significantly. NIR-II fluorescence imaging possesses a number of merits which prevail over the traditional and NIR-I (400-900 nm) imaging modalities in fundamental research, such as reduced photon scattering, as well as auto-fluorescence and improved penetration depth. Functional probes for instant and precise feedback of
information are at the core of this modality for superb imaging. Herein, we review the recently developed fluorophores including carbon nanotubes, organic small molecules, quantum dots, conjugated polymers and rare-earth-doped materials to present superior and multifunctionality of biomedical imaging in the NIR-II regions (1000-1700 nm).
This paper addresses the problem of global finite-time adaptive stabilization for a class of high-order uncertain nonlinear systems. A new finite-time stability result is established to provide a ...less conservative estimation of convergent time in uncertain situation, and a state feedback stabilizer with an adaptive mechanism is constructed by applying continuous domination to adaptive fashion of the systems to be considered. The main novelty of this paper is the skillful development of an analytic strategy and the delicate selection of Lyapunov functions in searching for the adaptive fast finite-time stabilizer. A benchmark example is given to demonstrate the effectiveness of the proposed strategy.
This paper is concerned with the improvement of finite-time stability theorem and its application in stabilizing a class of high-order nonlinear systems globally. The novel control strategy unifies ...the construction of Lyapunov functions, which are used to deal with high-order and low-order nonlinear growth rates separately in the existing results. Convergent time is shortened greatly without requiring large control effort, but it suffers long period from traditional finite-time stabilization scheme when initial state is far away from the origin. Finally, two simulation examples including a practical one are presented to illustrate the efficiency of the proposed strategy.
Abstract The circulating renin-angiotensin system (RAS) is a classic endocrine system that regulates cardiovascular homeostasis during physiologic and pathologic states. Accumulated evidence has ...shown the presence of components of RAS in various tissues, which are upregulated in certain pathological conditions. Locally produced angiotensin (Ang)II may play an important role in tissue repair/remodeling in autocrine and/or paracrine manners. Following acute myocardial infarction (MI), cardiac repair occurs in the infarcted myocardium and structural remodeling is developed in noninfarcted myocardium, which are accompanied by activated cardiac RAS. In this review, the current understanding of independent activation of cardiac RAS and its regulation in the pathogenesis of myocardial repair/remodeling after MI is discussed.
Since the first example of using a thiourea‐amine organocatalyst was reported in 2003, research on thiourea‐based amines and phosphines in asymmetric catalysis has shown the excellent performance of ...chiral thiourea‐amine/phosphine organocatalysts in a variety of highly enantioselective reactions. In this Minireview, the iconic catalysts and transformations are highlighted and discussed.
Thiourea‐amine/phosphine organocatalysts: Since the demonstration of the first example of using thiourea‐amine organocatalysts in 2003, research on thiourea‐based amines and phosphines in asymmetric catalysis has shown that they could successfully catalyze a variety of highly enantioselective reactions. In this Minireview, the iconic catalysts and transformations are summarized and discussed.
Active power decoupling methods are developed to deal with the inherent ripple power at twice the grid frequency in single-phase systems generally by adding active switches and energy storage units. ...They have obtained a wide range of applications, such as photovoltaic (PV) systems, light-emitting diodes (LEDs) drivers, fuel cell (FC) power systems, and electric vehicle (EV) battery chargers, etc. This paper provides a comprehensive review of active power decoupling circuit topologies. They are categorized into two groups in terms of the structure characteristics: independent and dependent decoupling circuit topologies. The former operates independently with the original converter, and the latter, however, shares the power semiconductor devices with the original converter partially and even completely. The development laws for the active power decoupling topologies are revealed from the view of "duality principle," "switches sharing," and "differential connection." In addition, the exceptions and special cases are also briefly introduced. This paper is targeted to help researchers, engineers, and designers to construct some new decoupling circuit topologies and properly select existing ones according to the specific application.
Brain organoids have been used to recapitulate the processes of brain development and related diseases. However, the lack of vasculatures, which regulate neurogenesis and brain disorders, limits the ...utility of brain organoids. In this study, we induced vessel and brain organoids respectively, and then fused two types of organoids together to obtain vascularized brain organoids. The fused brain organoids were engrafted with robust vascular network-like structures, and exhibited increased number of neural progenitors, in line with the possibility that vessels regulate neural development. Fusion organoids also contained functional blood-brain-barrier (BBB)-like structures, as well as microglial cells, a specific population of immune cells in the brain. The incorporated microglia responded actively to immune stimuli to the fused brain organoids and showed ability of engulfing synapses. Thus, the fusion organoids established in this study allow modeling interactions between the neuronal and non-neuronal components
, in particular the vasculature and microglia niche.
For microgrid in islanded operation, due to the effects of mismatched line impedance, the reactive power could not be shared accurately with the conventional droop method. To improve the reactive ...power sharing accuracy, this paper proposes an improved droop control method. The proposed method mainly includes two important operations: error reduction operation and voltage recovery operation. The sharing accuracy is improved by the sharing error reduction operation, which is activated by the low-bandwidth synchronization signals. However, the error reduction operation will result in a decrease in output voltage amplitude. Therefore, the voltage recovery operation is proposed to compensate the decrease. The needed communication in this method is very simple, and the plug-and-play is reserved. Simulations and experimental results show that the improved droop controller can share load active and reactive power, enhance the power quality of the microgrid, and also have good dynamic performance.
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Fluorescence imaging with deep penetration and low auto-fluorescence in the second near-infrared biochannel (NIR-II, 1000–1700 nm) was developed rapidly during the past decades. ...Organic materials such as organic small molecules and polymers are promising candidates for various biomedical studies owing to their low toxicity and facile chemical modification. Recently, scaffold-structural diversity and multifunctional utilization of NIR-II fluorophores attracted a lot of attentions as the gradually revealing shortcomings of first generation NIR-I organic fluorophores and unbalanced demand between single fluorescence imaging and clinical practice. In this review, organic emitters including NIR-II organic small molecules and polymers are discussed which focus on their multifunctional applications in biomedicine. Furthermore, we raised the current challenges and perspectives of NIR-II organic emitters.
Constant power loads may yield instability due to the well-known negative impedance characteristic. This paper analyzes the factors that cause instability of a dc microgrid with multiple dc-dc ...converters. Two stabilization methods are presented for two operation modes: 1) constant voltage source mode; and 2) droop mode, and sufficient conditions for the stability of the dc microgrid are obtained by identifying the eigenvalues of the Jacobian matrix. The key is to transform the eigenvalue problem to a quadratic eigenvalue problem. When applying the methods in practical engineering, the salient feature is that the stability parameter domains can be estimated by the available constraints, such as the values of capacities, inductances, maximum load power, and distances of the cables. Compared with some classical methods, the proposed methods have wider stability region. The simulation results based on MATLAB/simulink platform verify the feasibility of the methods.
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