bluuebunny/crossref_metadata_2025_split huggingface dataset:
Position‐specific 13C/12C analysis of amino acid carboxyl groups – automated flow‐injection analysis based on reaction with ninhydrin
Authors: Fry Brian , Carter James F. , Yamada Keita , Yoshida Naohiro , Juchelka Dieter 
Published: March 2018

RationaleThe fundamental level of stable isotopic knowledge lies at specific atomic positions within molecules but existing methods of analysis require lengthy off‐line preparation to reveal this information. An automated position‐specific isotope analysis (PSIA) method is presented to determine the stable carbon isotopic compositions of the carboxyl groups of amino acids (δ13CCARBOXYL values). This automation makes PSIA measurements easier and routine.MethodsAn existing high‐performance liquid chromatography (HPLC) gas handling interface/stable isotope ratio mass spectrometry system was modified by the addition of a post‐column derivatisation unit between the HPLC system and the interface. The post‐column reaction was optimised to yield CO2 from the carboxyl groups of amino acids by reaction with ninhydrin.ResultsThe methodology described produced δ13CCARBOXYL values with typical standard deviations below ±0.1 ‰ and consistent differences (Δ13CCARBOXYL values) between amino acids over a 1‐year period. First estimates are presented for the δ13CCARBOXYL values of a number of internationally available amino acid reference materials.ConclusionsThe PSIA methodology described provides a further dimension to the stable isotopic characterisation of amino acids at a more detailed level than the bulk or averaged whole‐molecule level. When combined with on‐line chromatographic separation or off‐line fraction collection of protein hydrolysates the technique will offer an automated and routine way to study position‐specific carboxyl carbon isotope information for amino acids, enabling more refined isotopic studies of carbon uptake and metabolism.
Three‐dimensional augmented reality surgical navigation with hybrid optical and electromagnetic tracking for distal intramedullary nail interlocking
Authors: Ma Longfei , Zhao Zhe , Zhang Boyu , Jiang Weipeng , Fu Ligong , Zhang Xinran , Liao Hongen 
Published: March 2018

AbstractBackgroundIntramedullary nail (IMN) fixation improves functional outcomes for the diaphyseal fractures of long bones. However, locking the distal holes of the IMN is challenging. Although several navigation methods have been proposed, an intuitive, radiation‐free and accurate navigation method that does not suffer from problems of hand–eye coordination has not yet been described.MethodsThis paper proposes an augmented reality (AR) surgical navigation method with hybrid optical and electromagnetic (EM) tracking for distal IMN interlocking. Model experiments are designed to evaluate the AR‐guided distal interlocking method.ResultsAR‐guided drilling procedures were performed on 5 tibia models and a leg phantom. The accuracy (hit or miss) was evaluated using fluoroscopy. The experimental results demonstrated that all 18 drills successfully hit the distal holes at a rate of 100%.ConclusionsOur results indicate that the AR‐guided distal interlocking method is feasible and has many potential applications in clinic after further evaluation.
Distributed consensus of second‐order multiagent systems with nonconvex input constraints
Authors: Mo Lipo , Lin Peng 
Published: March 2018

SummaryThis paper addresses the input constrained consensus of second‐order multiagent systems with nonconvex constraints. A new update law is proposed to make the position states of all agents converge to a common point and the velocities converge to zero, while the input of each agent stays in a certain constraint set. The closed‐loop system is first converted to an equivalent system by taking a novel coordinate transformation. Then, it is proved that the input constrained consensus can be achieved if the graphs jointly have directed spanning trees by using the Metzler matrix theory. Finally, simulations are provided to demonstrate the effectiveness of the proposed algorithm.
Practical time‐varying formation tracking for high‐order nonlinear multiagent systems with multiple leaders based on the distributed disturbance observer
Authors: Yu Jianglong , Dong Xiwang , Liang Zixuan , Li Qingdong , Ren Zhang 
Published: March 2018

SummaryPractical time‐varying formation tracking analysis and design problems for high‐order nonlinear multiagent systems with directed interaction topologies are investigated by using the distributed disturbance observer, where the time‐varying formation tracking error can be controlled within an arbitrarily small bound. Different from the previous work, there exists a predefined time‐varying formation formed by the states of the followers and the formation tracks the convex combination of the states of the leaders with unknown control inputs. Besides, the leaders can be multiple, and the dynamics of each follower has heterogeneous nonlinearity and disturbance. First, a distributed disturbance observer‐based practical time‐varying formation tracking protocol is constructed using neighboring relative information, where only a part of the followers, which are named as well‐informed ones, are required to obtain the information of the multiple leaders. The proposed protocol can process the heterogeneous nonlinearity, the disturbance of each follower, and the unknown control inputs of the leaders simultaneously. Then, an algorithm with 2 steps is presented to design the practical time‐varying formation tracking protocol by solving an algebraic Riccati equation and an algebraic equation, where the time‐varying formation tracking feasibility condition is introduced. Moreover, the stability of the closed‐loop multiagent system under the proposed protocol is proved by using the properties of the Laplacian matrix and the Lyapunov stability theory. Finally, a numerical simulation example is provided to illustrate the effectiveness of the obtained theoretical results.
Time‐varying feedback for stabilization in prescribed finite time
Authors: Song Yongduan , Wang Yujuan , Krstic Miroslav 
Published: March 2018

SummaryThis paper provides a time‐varying feedback alternative to control of finite‐time systems, which is referred to as “prescribed‐time control,” exhibiting several superior features: (i) such time‐varying gain–based prescribed‐time control is built upon regular state feedback rather than fractional‐power state feedback, thus resulting in smooth (Cm) control action everywhere during the entire operation of the system; (ii) the prescribed‐time control is characterized with uniformly prespecifiable convergence time that can be preassigned as needed within the physically allowable range, making it literally different from not only the traditional finite‐time control (where the finite settling time is determined by a system initial condition and a number of design parameters) but also the fixed‐time control (where the settling time is subject to certain constraints and thus can only be specified within the corresponding range); and (iii) the prescribed‐time control relies only on regular Lyapunov differential inequality instead of fractional Lyapunov differential inequality for stability analysis and thus avoids the difficulty in controller design and stability analysis encountered in the traditional finite‐time control for high‐order systems.
Adaptive decentralized fault‐tolerant tracking control for large‐scale nonlinear systems with input quantization
Authors: Wang Cai‐Cheng , Yang Guang‐Hong 
Published: March 2018

SummaryIn this paper, an adaptive decentralized tracking control scheme is designed for large‐scale nonlinear systems with input quantization, actuator faults, and external disturbance. The nonlinearities, time‐varying actuator faults, and disturbance are assumed to exist unknown upper and lower bounds. Then, an adaptive decentralized fault‐tolerant tracking control method is designed without using backstepping technique and neural networks. In the proposed control scheme, adaptive mechanisms are used to compensate the effects of unknown nonlinearities, input quantization, actuator faults, and disturbance. The designed adaptive control strategy can guarantee that all the signals of each subsystem are bounded and the tracking errors of all subsystems converge asymptotically to zero. Finally, simulation results are provided to illustrate the effectiveness of the designed approach.
Robust adaptive quantized DSC of uncertain pure‐feedback nonlinear systems with time‐varying output and state constraints
Authors: Xia Xiaonan , Zhang Tianping 
Published: March 2018

SummaryIn this paper, the problem of neural adaptive dynamic surface quantized control is studied the first time for a class of pure‐feedback nonlinear systems in the presence of state and output constraint and unmodeled dynamics. The considered system is under the control of a hysteretic quantized input signal. Two types of one‐to‐one nonlinear mapping are adopted to transform the pure‐feedback system with different output and state constraints into an equivalent unconstrained pure‐feedback system. By designing a novel control law based on modified dynamic surface control technique, many assumptions of the quantized system in early literary works are removed. The unmodeled dynamics is estimated by a dynamic signal and approximated based on neural networks. The stability analysis indicates that all the signals in the closed‐loop system are semiglobally uniformly ultimately bounded, and the output and all the states remain in the prescribed time‐varying or constant constraints. Two numerical examples with a coarse quantizer show that the proposed approach is effective for the considered system.
Adaptive asymptotic stabilization of switched parametric strict‐feedback systems with switched control
Authors: Zhai Ding , An Liwei , Zhang Qing‐Ling 
Published: March 2018

SummaryThis paper is concerned with the problem of adaptive stabilization for a class of switched linear‐parametric nonlinear systems under arbitrary switching. The traditional adaptive backstepping control is successfully extended to switched systems from nonswitched ones where the asymptotic regulation of system state is not destroyed due to rapid or abrupt changes of switching parameters. A new switched adaptive controller is designed by exploiting a common high‐order Lyapunov function with a σ‐modification mechanism, which can reflect sufficiently the changes of plant by designing different adaptive laws and control laws for different subsystems. An explicit formula for constructing a continuous and piecewise
virtual control function is given to remove the restriction where some
bound functions have to be constructed blindly by designers in the existing results, which may be somewhat too strict to be applied. A numerical example is provided to validate the proposed approach.
Homogeneous control law design for output synchronization of networked Lur'e‐type systems with disturbances
Authors: Li Ranran , Yang Guang‐Hong 
Published: March 2018

SummaryIn this paper, the homogeneous distributed control law is proposed such that the outputs of the networked Lur'e systems with disturbances are synchronized. A novel adaptive distributed state‐based disturbance compensator technique is utilized such that the disturbances can be offset asymptotically. The design of the distributed compensator is constructive in that some particular functions of the states of the Lur'e systems are included. The functions always exist for the considered Lur'e‐type system. Moreover, a theorem of networked Lur'e systems subject to disturbances is first presented to show the boundedness of the states of the closed‐loop system. Then, the synchronization is shown by the incremental passivity theory and graph theory. Finally, the effectiveness of the current method is illustrated by the networked Van der Pol oscillators with disturbances.
A Simultaneous Analysis of Relations Between L1 and L2 Skills in Reading and Writing
Authors: Pae Tae‐Il 
Published: March 2018

AbstractThis study examines relations between the first language (L1) and second language (L2) in reading and writing for 211 upper middle school Korean students learning English as a foreign language. Results using path analysis suggest that L1 ability is a significant independent predictor of L2 ability in both reading and writing, providing evidence of interdependent relations between L1 and L2 operations in receptive and productive skills. Results also indicate that L1 reading predicted L2 writing, but L1 writing did not predict L2 reading. L2 proficiency was also shown to be important. L2 proficiency made a greater contribution to L2 reading and writing operations than L1 ability did. Also, the relation between L1 and L2 writing skills but not reading skills was significantly moderated by L2 proficiency. The author discusses results in the context of existing theories about L1–L2 relations and highlights important implications for pedagogy and future research.
Outside CEOs and innovation
Authors: Cummings Trey , Knott Anne Marie 
Published: March 2018

Research Summary: Innovation is the principle driver of firm and economic growth. Thus, one disturbing trend that may explain stagnant growth is a 65% decline in firms’ R&D productivity. We propose that the rise of outside Chief Executive Officers (CEOs) may be partially responsible for the decline because those CEOs are more likely to lack technological domain expertise necessary to manage R&D effectively. While this proposition was motivated by interviews with Chief Technology Officers (CTOs), we test it at large scale. We find that firm R&D productivity decays during the tenure of outside CEOs relative to that of inside CEOs. We further find this effect is more pronounced for firms with high R&D intensity and for firms employing outside CEOs with more remote experience, lending circumstantial support for the underlying assumption regarding lack of expertise. Note that this is not a call for boards to avoid outside CEOs, rather it is recommendation to consider the implications for innovation.
Managerial Summary: While outside CEOs offer advantages over internal candidates, we argue one unintended consequence is weaker innovation. This argument was prompted by two coincident trends: a 65% decline in companies’ R&D productivity and a doubling of outside Chief Executive Officers (CEOs). The argument was reinforced by interviews with Chief Technology Officers (CTOs), who recounted shifts in orientation from R&D as an investment to R&D as an expense that occurred shortly in response to a new CEO. We felt this shift was more likely with outside CEOs because they may lack technological domain expertise necessary to effectively manage R&D. Our results are consistent with the argument—company R&D productivity decreases under outside CEOs. Note, however, that we don’t advocate avoiding outside CEOs, rather we recommend R&D firms consider technological domain expertise during CEO hiring.
Quantitative Analysis of Multiple Proteins of Different Invasive Tumor Cell Lines at the Same Single‐Cell Level
Authors: Zhang Xiangchun , Liu Ru , Shu Qingming , Yuan Qing , Xing Gengmei , Gao Xueyun 
Published: March 2018

AbstractTumor cell invasion is pivotal to the development, metastasis, and prognosis of tumors. It is reported that the invasive ability of tumor cells is mainly dependent on the expression levels of membrane type‐1 matrix metalloproteinase (MT1‐MMP) and integrin αVβ3 proteins on cell membranes. To precisely distinguish between tumor cells with different invasive abilities, it is important to establish a highly sensitive and precise quantification method to differentiate the expression levels of MT1‐MMP and integrin αVβ3 in the same single tumor cell at the same time. Herein, two functional peptides to construct red‐emissive Au26 clusters and green‐emissive Ag12 clusters are reported. Moreover, the Au26 clusters and Ag12 clusters have the ability to specifically target MT1‐MMP and integrin αVβ3, respectively, in the same single cell at the same time. By utilizing the fluorescent properties and metallic compositions of metal clusters, the MT1‐MMP and integrin αVβ3 levels of the more invasive SiHa cells or the less invasive HeLa cells are simultaneously and quantitatively differentiated via laser ablation inductively coupled plasma mass spectrometry. This method of quantitatively detecting multiple invasive proteins on the same cell is of great value for accurately diagnosing aggressive tumors and monitoring the invasiveness of these tumors.
Electrochemical Biosensor Composed of Silver Ion‐Mediated dsDNA on Au‐Encapsulated Bi2Se3 Nanoparticles for the Detection of H2O2 Released from Breast Cancer Cells
Authors: Mohammadniaei Mohsen , Yoon Jinho , Lee Taek , Bharate Bapurao G. , Jo Jinhee , Lee Donghyun , Choi Jeong‐Woo 
Published: March 2018

AbstractA newly developed electrochemical biosensor composed of a topological insulator (TI) and metallic DNA (mDNA) is fabricated. The bismuth selenide nanoparticle (Bi2Se3 NP) is synthesized and sandwiched between the gold electrode and another Au‐deposited thin layer (Bi2Se3@Au). Then, eight‐silver‐ion mediated double‐stranded DNA (mDNA) is immobilized onto the substrate (Bi2Se3@Au‐mDNA) for the further detection of hydrogen peroxide. The Bi2Se3 NP acts as the electrochemical‐signal booster, while unprecedentedly its encapsulation by the Au thin layer keeps the TI surface states protected, improves its electrochemical‐signal stability and provides an excellent platform for the subsequent covalent immobilization of the mDNA through Au–thiol interaction. Electrochemical results show that the fabricated biosensor represents much higher Ag+ redox current (≈10 times) than those electrodes prepared without Bi2Se3@Au. The characterization of the Bi2Se3@Au‐mDNA film is confirmed by atomic force microscopy, scanning tunneling microscopy, and cyclic voltammetry. The proposed biosensor shows a dynamic range of 00.10 × 10−6m to 27.30 × 10−6m, very low detection limit (10 × 10−9m), unique current response (1.6 s), sound H2O2 recovery in serum, and substantial capability to classify two breast cancer subtypes (MCF‐7 and MDA‐MB‐231) based on their difference in the H2O2 generation, offering potential applications in the biomedicine and pharmacology fields.
A Generic Self‐Assembly Process in Microcompartments and Synthetic Protein Nanotubes
Authors: Uddin Ismail , Frank Stefanie , Warren Martin J. , Pickersgill Richard W. 
Published: March 2018

AbstractBacterial microcompartments enclose a biochemical pathway and reactive intermediate within a protein envelope formed by the shell proteins. Herein, the orientation of the propanediol‐utilization (Pdu) microcompartment shell protein PduA in bacterial microcompartments and in synthetic nanotubes, and the orientation of PduB in synthetic nanotubes are revealed. When produced individually, PduA hexamers and PduB trimers, tessellate to form flat sheets in the crystal, or they can self‐assemble to form synthetic protein nanotubes in solution. Modelling the orientation of PduA in the 20 nm nanotube so as to preserve the shape complementarity and key interactions seen in the crystal structure suggests that the concave surface of the PduA hexamer faces out. This orientation is confirmed experimentally in synthetic nanotubes and in the bacterial microcompartment produced in vivo. The PduB nanotubes described here have a larger diameter, 63 nm, with the concave surface of the trimer again facing out. The conserved concave surface out characteristic of these nano‐structures reveals a generic assembly process that causes the interface between adjacent subunits to bend in a common direction that optimizes shape complementarity and minimizes steric clashes. This understanding underpins engineering strategies for the biotechnological application of protein nanotubes.
Transition‐Metal‐Based Electrocatalysts as Cocatalysts for Photoelectrochemical Water Splitting: A Mini Review
Authors: Li Deng , Shi Jingying , Li Can 
Published: March 2018

AbstractConverting solar energy into hydrogen via photoelectrochemical (PEC) water splitting is one of the most promising approaches for a sustainable energy supply. Highly active, cost‐effective, and robust photoelectrodes are undoubtedly crucial for the PEC technology. To achieve this goal, transition‐metal‐based electrocatalysts have been widely used as cocatalysts to improve the performance of PEC cells for water splitting. Herein, this Review summarizes the recent progresses of the design, synthesis, and application of transition‐metal‐based electrocatalysts as cocatalysts for PEC water splitting. Mo, Ni, Co‐based electrocatalysts for the hydrogen evolution reaction (HER) and Co, Ni, Fe‐based electrocatalysts for the oxygen evolution reaction (OER) are emphasized as cocatalysts for efficient PEC HER and OER, respectively. Particularly, some most efficient and robust photoelectrode systems with record photocurrent density or durability for the half reactions of HER and OER are highlighted and discussed. In addition, the self‐biased PEC devices with high solar‐to‐hydrogen efficiency based on earth‐abundant materials are also addressed. Finally, this Review is concluded with a summary and remarks on some challenges and opportunities for the further development of transition‐metal‐based electrocatalysts as cocatalysts for PEC water splitting.
Ultraviolet Photoluminescence of Carbon Nanospheres and its Surface Plasmon‐Induced Enhancement
Authors: Gan Zhixing , Pan Pengfei , Chen Zhihui , Meng Ming , Xu Hao , Yu Zhizhou , Chang Chenliang , Tao Yongchun 
Published: March 2018

AbstractUltraviolet (UV) light can be used in versatile applications ranging from photoelectronic devices to biomedical imaging. In the development of new UV light sources, in this study, stable UV emission at ≈350 nm is unprecedentedly obtained from carbon nanospheres (CNSs). The origin of the UV fluorescence is comprehensively investigated via various characterization methods, including Raman and Fourier transform infrared analyses, with comparison to the visible emission of carbon nanodots. Based on the density functional calculations, the UV fluorescence is assigned to the carbon nanostructures bonded to bridging O atoms and dangling –OH groups. Moreover, a twofold enhancement in the UV emission is acquired for Au‐carbon core‐shell nanospheres (Au‐CNSs). This remarkable modification of the UV emission is primarily ascribed to charge transfer between the CNSs and the Au surface.
Printing 1D Assembly Array of Single Particle Resolution for Magnetosensing
Authors: Gao Meng , Kuang Minxuan , Li Lihong , Liu Meijin , Wang Libin , Song Yanlin 
Published: March 2018

AbstractMagnetosensing is a ubiquitous ability for many organism species in nature. 1D assembly, especially that arranged in single‐particle‐resolution regulation, is able to sense the direction of magnetic field depending on the enhanced dipolar interaction in the linear orientation. Inspired by the magnetosome structure in magnetotactic bacteria, a 1D assembly array of single particle resolution with controlled length and well‐behaved configuration is prepared via inkjet printing method assisted with magnetic guiding. In the fabrication process, chains in a “tip‐to‐tip” regulation with the desired number of particles are prepared in a confined tiny inkjet‐printed droplet. By adjusting the receding angle of the substrate, the assembled 1D morphology is kept/deteriorated depending on the pinning/depinning behavior during ink evaporation, which leads to the formation of well‐behaved 1D assembly/aggregated dot assembly. Owing to the high‐aspect‐ratio characteristic of the assembled structure, the as‐prepared 1D arrays can be used for magnetic field sensing with anisotropic magnetization M///M⊥ up to 6.03.