The photo-/electrocatalytic functionalization of quinoxalin-2(1H)-ones has emerged as a promising and powerful approach for post-synthetic modification of quinoxalin-2(1H)-ones. This review provides ...an overview of recent developments in photo-/electrocatalytic functionalization of quinoxalin-2(1H)-ones including arylation, alkylation, fluoroalkylation, amination, phosphorylation, acylation, alkoxylation, thiolation, silylation, and annulation. The reaction scope and the related mechanism are also well discussed.
The photo-/electrocatalytic functionalization of quinoxalin-2(1H)-ones has emerged as a promising and powerful approach for the post-synthetic modification of quinoxalin-2(1H)-ones. This review provides an overview of recent developments in the photo-/electrocatalytic functionalization of quinoxalin-2(1H)-ones.
A boundary control approach is used to control a two-link rigid-flexible wing in this article. Its design is based on the principle of bionics to improve the mobility and the flexibility of aircraft. ...First, a series of partial differential equations (PDEs) and ordinary differential equations (ODEs) are derived through the Hamilton's principle. These PDEs and ODEs describe the governing equations and the boundary conditions of the system, respectively. Then, a control strategy is developed to achieve the objectives including restraining the vibrations in bending and twisting deflections of the flexible link of the wing and achieving the desired angular position of the wing. By using Lyapunov's direct method, the wing system is proven to be stable. The numerical simulations are carried out with the finite difference method to prove the effectiveness of designed boundary controllers.
Turbulent interfacial evolution at the Zn anode/electrolyte, leading to rampant dendrites and parasitic reactions, is responsible for low Coulombic efficiency (CE) and premature failure in Zn metal ...batteries. To address this issue, an integrated eutectic electrolyte was introduced to construct a gradient organic/inorganic hybrid SEI (GHS) layer on the Zn anode through in situ chemical reconstruction. The entanglement between the thermodynamic equilibrium of the species and the evolution of the GHS layer in a coordinated state was revealed. The GHS layer with a gradient structure and composition alleviates corrosion and passivation on the Zn anode, as well as the hydrogen evolution reaction. Additionally, the diffusion behavior of Zn2+ at the interface is optimized, allowing epitaxial deposition of Zn2+ along the (002) plane to eradicate dendrites. This results in an ultra-stable Zn anode with a substantially improved CE of 99.8% over 1200 cycles and a high cumulative plated capacity of 5.57 A h cm−2 at 5 mA cm−2. The effectiveness of this approach is demonstrated by the extremely long lifespan of 22 000 cycles of a Zn//V2O5 full cell.
In cereal endosperm, the deficiency of starch branching enzyme (SBE) can change starch morphology and structure, forming heterogeneous starch granules. The contents and types of heterogeneous ...granules in endosperm influence the quality and utilizations of cereal seeds. This review summarizes the morphologies, physicochemical properties, and formation mechanisms of heterogeneous granules in cereal endosperm lacking SBE. Some future researches on heterogeneous granules are also suggested. The heterogeneous granules can be divided into heteromorphous and biphasic granules. Heteromorphous granules including aggregate, elongated, hollow and sickle granules have different morphologies, and are detected in rice, maize, wheat and barley endosperms lacking SBE. The different heteromorphous granules show different starch components, molecular structures, thermal properties, and hydrolysis resistances. Biphasic granules have different organizational and molecular structures between their inner and outer regions, and are mainly reported in rice and maize endosperms lacking SBEIIb. The heterogeneous granules have regional distribution in endosperm. The amylose molecules from adjacent starch subgranules in one amyloplast form anti-parallel double helices, leading to the fusion of subgranules and the formation of aggregate and elongated granules. The changed amylopectin with long branch-chains and low branching degree is mainly responsible for the formation of biphasic granules. The differently changed extents of SBE in different regions of endosperm and at different development stages of starch result in different heterogeneous granules and their regional distribution in endosperm.
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•Heterogeneous starches exist in cereal endosperm lacking starch branching enzyme.•Heterogeneous starches contain heteromorphous granules and biphasic granules.•Some heteromorphous granules are formed through amylose anti-parallel double helices.•Amylopectin long branch-chains are responsible for the formation of biphasic granule.•Starch branching enzyme doses play a decisive role in forming heterogeneous starches.
The development of green and convenient methods for C–S bond formation has received significant attention because C–S bond widely occurs in many important pharmaceutical and biological compounds. ...Recently, visible-light photoredox catalysis has been established as an efficient and general tool for the construction of C–C and C-heteroatom bonds. In this review, we have focused on the research on recent advances in C–S bond formation via visible-light photoredox catalysis, and the growing opportunities they present to the construction of complex chemical scaffolds for applications encompassing bioactive molecules synthesis, synthetic methodology development, and sulfur-containing drugs. We hope that this review will provide chemists with a synthetic tool that will open the door to further development of organsulfur chemistry
Display omitted In this review, we highlight the recent advances of C–S bond formation via visible-light photoredox catalysis, and analyze the reaction mechanism of various transformations in detail. We hope that this review will provide chemists with a synthetic tool and open new avenues for further development of organsulfur chemistry.
•An optimal neural network is used to model SOC as a function of system measurements.•This modeling approach eliminates the need to determine an OCV–SOC relationship.•UKF is employed to improve the ...accuracy of the neural network-based SOC estimation.•Driving cycle case studies are presented to validate the developed method.
Lithium-ion batteries have been widely used as the energy storage systems in personal portable electronics (e.g. cell phones, laptop computers), telecommunication systems, electric vehicles and in various aerospace applications. To prevent the sudden loss of power of battery-powered systems, there are various approaches to estimate and manage the battery's state of charge (SOC). In this paper, an artificial neural network–based battery model is developed to estimate the SOC, based on the measured current and voltage. An unscented Kalman filter is used to reduce the errors in the neural network-based SOC estimation. The method is validated using LiFePO4 battery data collected from the Federal Driving Schedule and dynamical stress testing.
Knowledge management (KM) research has yielded extensive explanations regarding the individual's motivation to share knowledge, each with different sets of factors. Yet the study of continued ...knowledge sharing is rare. There has been little research investigating this issue from contributing and seeking perspectives—the two distinct, but closely interrelated, facets of continued knowledge sharing. We propose that knowledge management system (KMS) users' beliefs are contextually differentiated, and thus a distinction between knowledge-contribution and knowledge-seeking behaviors and an adequate emphasis on their variance in terms of user belief is needed. By incorporating the knowledge-contribution and knowledge-seeking perspectives in a single study, we model and examine the differences among driving factors in two behavioral contexts, provide the conceptual comparisons and preliminary discussions, and thus advance our understanding of continued knowledge sharing via the KMS.
A high-resolution sensor using a piezoelectric drum transducer is proposed for power frequency current sensing (50 Hz or 60 Hz). The utilization of the magnetic circuit helps to enhance the response ...to the electric currents in the power cords. The high sensitivity of the sensor originates from the superposition of the Ampere forces and the amplified piezoelectric effect of the drum transducer. The feasibility of the sensor was verified by experiments. The device exhibits a broad 3 dB bandwidth of 67.4 Hz without an additional magnetic field bias. The average sensitivity is 31.34 mV/A with a high linearity of 0.49%, and the resolution of the sensor attains 0.02 A. The resolution is much higher than that of the previous piezoelectric heterostructure for two-wire power-cords. Error analysis shows that the uncertainty reaches 0.01865 mV at the current of 2.5 A. Meanwhile, the device can generate a load power of 447.9 nW with an optimal load resistance of 55 KΩ at 10A (f = 50 Hz) in energy harvesting experiments. The features of high sensitivity, excellent linearity, high resolution, low costs, and convenient installation demonstrate the application prospect of the proposed device for measuring power frequency currents in electric power grids.
The mechanism behind osteonecrosis of the femoral head (ONFH) remains unclear. The aim of this study was to explore the pathogenesis of ONFH from a biomechanical standpoint to provide a theoretical ...basis for improved treatments. We compared the bone structure of fractured femoral heads with that of necrotic femoral heads by Micro-CT scanning and histological evaluation. In addition, we compared the biomechanical properties of each zone in fractured femoral heads with those in necrotic femoral heads by using biomechanical tests. Compared with fractured femoral heads, bone microarchitecture and bone morphometry in necrotic zone and sclerotic zone of necrotic femoral heads have altered markedly. In addition, the biomechanical properties of the necrotic zone in femoral heads weaken markedly, while those of the sclerotic zone strengthen. We hypothesize that discordance between bone structure and function of the femoral head may be involved in the pathogenesis of ONFH and that more attention should be paid to the prevention and treatment of such discordance.
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