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An ionothermal reaction has generated a cobalt hydroxyacetate magnet that contains a three-dimensional Co–O–Co framework consisting of vertex-sharing octahedral chains bridged by another octahedra viaedge-sharing and shows spin glass behavior. [ABSTRACT FROM AUTHOR]

Abstract: The solvothermal treatment of cobalt nitrate (or zinc acetate), ethylenediamine and dicarboxylate in acetonitrile produced two one-dimensional coordination polymers [Co(mimz)2(ox)] n (1) and [Zn(mimz)2(ip)] n (2) (mimz = 2-methylimidazoline, ox=oxalate, ip=isophthalate) which ligand involving in situ formation of imidazoline ligand by cycloaddition reaction of ethylenediamine and acetonitrile. [Copyright &y& Elsevier]

Luban locks with mortise and tenon structure have structural diversity and architectural stability, and it is extremely challenging to synthesize Luban lock‐like structures at the molecular level. In this work, we report the cocrystallization of two structurally related atom‐precise fcc silver nanoclusters Ag110(SPhF)48(PPh3)12 (Ag110) and Ag14(μ6‐S)(SPhF)12(PPh3)8 (Ag14). It is worth noting that the Ag110 cluster is the first compound to simulate the complex Luban lock structure at the molecular level. Meanwhile, Ag110 is the largest known fcc‐based silver nanocluster, so far, there is no precedent for fcc silver nanocluster with more than 100 silver atoms. DFT calculations show that Ag110 is a 58‐electron superatom with an electronically closed shell1S21P61D102S21F142P61G18. Ag110⋅Ag14 can rapidly catalyze the reduction of 4‐nitrophenol within 4 minutes. In addition, Ag110 presents clear structural evidence to reveal the critical size and mechanism of the transformation of metal core from fcc stacking to quasi‐spherical superatom. This research work provides an important structural model for studying the nucleation mechanism and structural assembly of silver nanoclusters. [ABSTRACT FROM AUTHOR]

Luban locks with mortise and tenon structure have structural diversity and architectural stability, and it is extremely challenging to synthesize Luban lock‐like structures at the molecular level. In this work, we report the cocrystallization of two structurally related atom‐precise fcc silver nanoclusters Ag110(SPhF)48(PPh3)12 (Ag110) and Ag14(μ6‐S)(SPhF)12(PPh3)8 (Ag14). It is worth noting that the Ag110 cluster is the first compound to simulate the complex Luban lock structure at the molecular level. Meanwhile, Ag110 is the largest known fcc‐based silver nanocluster, so far, there is no precedent for fcc silver nanocluster with more than 100 silver atoms. DFT calculations show that Ag110 is a 58‐electron superatom with an electronically closed shell1S21P61D102S21F142P61G18. Ag110⋅Ag14 can rapidly catalyze the reduction of 4‐nitrophenol within 4 minutes. In addition, Ag110 presents clear structural evidence to reveal the critical size and mechanism of the transformation of metal core from fcc stacking to quasi‐spherical superatom. This research work provides an important structural model for studying the nucleation mechanism and structural assembly of silver nanoclusters. [ABSTRACT FROM AUTHOR]

This article presents an additive-state-decomposition-based repetitive control (RC) method for a class of nonlinear systems with nonintegral-chain form and multiple mismatched disturbances. The key idea of this method is to decompose the original tracking problem for an uncertain nonlinear system into two tractable subproblems, namely RC problem for a primary linear time-invariant (LTI) periodic system and robust stabilization problem for a nonlinear secondary system. By taking the equivalent total effect of the multiple disturbances as one matched total disturbance, an improved linear extended state observer (ILESO) is constructed to estimate and compensate for the adverse effect of the multiple disturbances. The method has three significant features: First, it builds a bridge between the existing RC methods for LTI systems and nonlinear systems and, thus, broadens the application scope of RC; second, besides the known information of the model being used to the design of ILESO, the periodic nonlinearity in the plant is extracted to be treated by RC, which enhances both the transient and steady-state performances; and third, the ILESO-based control scheme and the RC law are designed separately, which is flexible for system design. The stability criterion and design procedure are presented in detail. Finally, numerical and experimental results illustrate the validity and superiorities of the method. [ABSTRACT FROM AUTHOR]

The salt decay on the surface of stone cultural relics is the greatest damage to its loaded information. Polycarboxylate modifiers can reduce salt crystallization pressure and/or change crystal habits, thereby becoming a new method for controlling salt crystallization damage in pores. However, the lack of precise regulation of crystal morphology by modifier and the unclear relationship between modifier and crystal transformation during salt growth hinder its practical application. Herein, diethylenetriamine pentamethylene phosphonic acid (DTPMP), phosphorus-free, green polyaspartic acid (PASP) and polyepoxysuccinic acid (PESA), as well as three composite modifiers composed of DTPMP and PESA (M-1:9, M-2:8, M-3:7) were systematically investigated. Video microscope, scanning electron microscope, and X-ray diffraction showed that the addition of these modifier could obviously transform the crystal morphology of sodium sulfate(thenardite) from prism into dendrite, which was related to the significant change in the intensity ratios of corresponding peaks on the different crystal planes. Molecular dynamics simulations were conducted to investigate the interactions of PASP and PESA on different surfaces of sodium sulfate, revealing that the crystal transformation of sodium sulfate was mainly influenced by the coordination/adsorption effect of the modifiers on the (010) plane. All modifiers were used for sandstone desalination, and the clean and desalted sandstones were analyzed for desalting efficiency, colorimetry and porosity, which showed that PESA, PASP and composite modifier M-3:7 all promoted the precipitation of sodium sulfate on the surface. Especially, composite modifier M-3:7 prefers to change the crystallization and morphology of sodium sulfate from prism into dendritic flower, which can be used to protect to sandstone cultural relics from salt damage. • The polycarboxylate PASP and PESA, and composite modifier can modify crystal habit of sodium sulfate. • Molecular dynamics is used to elucidate the modification mechanism of PASP and PESA. • The presence of PESA, PASP, M-3:7 is conducive to the in-situ protection of sandstone cultural relics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Well-tuned band structure and redox ability by adjusting electron D-A capacity of building units. • Selective thiocyanate/sulfonyl radicals generation by h+ oxidation. • Reactive oxygen species production by photogenerated e− reduction. • Tandem sulfur-based radical addition/vinyl radical coupling with ROS/enol tautomerism. • No electron sacrificial agents or extra additives as precursor of singe electron transfer reagents. Photocatalytic radical-mediated aerobic thiocyanation/sulfonylation of alkynes represents the most straightforward and atom-economic method to synthesize α-thiocyanate/sulfonyl ketones. The core issue is the generation of desired thiocyanate/sulfonyl radicals and their subsequent conversion into target products. In this work, three polyimide-based donor–acceptor COFs, named TAPB-PMDA, TTA-PMDA, and TTA-NDA, respectively, have been prepared for the photosynthesis of α-thiocyanate/sulfonyl ketones. Based on efficient adjusting electron donor-accept capacity of building units, TTA-NDA possesses broader visible absorption, richer redox properties, faster carrier separation efficiency and shows higher photocatalytic activity in thiocyanation/sulfonylation of alkynes under blue LED light illumination. Control experiments and EPR tests provide insight into the tandem radical addition/cross-coupling mechanism, in which the thiocyanate/sulfonyl radicals generation via h+ oxidation and the reactive oxygen species (ROS, e.g. •OH, H 2 O 2 , 1O 2 , O 2 •−) production by e− reduction carry out simultaneously, avoiding the employing of electron sacrificial agents or extra additives as precursors of singe electron transfer reagents. This operable strategy opens up a door for the difunctionalization of alkynes in photosynthetic manner. [ABSTRACT FROM AUTHOR]

The electrocatalytic splitting of water to produce hydrogen is regarded as an efficient and promising strategy but is limited by its large overpotential; thus, a highly efficient electrocatalyst is urgently needed. Mixed metal doping is an important strategy in defect engineering because the heteroatoms can change the intrinsic structure to form defects by affecting the atomic coordination mode and adjusting the electronic structure, which is often accompanied by morphological changes. Herein, two-dimensional layered bimetallic Co–pydc containing axially coordinated water molecules was selected by producing surface defects through Fe doping in Co centers as bifunctional electrocatalysts for OER and HER. The optimized Co0.59Fe0.41–pydc possesses outstanding OER performance with the lowest overpotential of 262 mV to reach j = 10 mA cm−2, and Co0.75Fe0.25–pydc possesses superior HER performance with the lowest overpotential of 96 mV at j = 10 mA cm−2. Furthermore, the overall water splitting device assembled with Co0.59Fe0.41–pydc@NF//Co0.59Fe0.41–pydc@NF affords a current density of 10 mA cm−2 at only 1.687 V. This work emphasizes the surface defects formed by tuning the electronic structure of metal centres accompanied with morphological changes of bimetallic dopants for efficient overall water splitting. [ABSTRACT FROM AUTHOR]

Developing efficient and robust hydrogen evolution reaction (HER) catalysts for scalable and sustainable hydrogen production through electrochemical water splitting is strategic and challenging. Herein, heterogeneous Mo8O26‐NbNxOy supported on N‐doped graphene (defined as Mo8O26‐NbNxOy/NG) is synthesized by controllable hydrothermal reaction and nitridation process. The O‐exposed Mo8O26 clusters covalently confined on NbNxOy nanodomains provide a distinctive interface configuration and appropriate electronic structure, where fully exposed multiple active sites give excellent HER performance beyond commercial Pt/C catalyst in pH‐universal electrolytes. Theoretical studies reveal that the Mo8O26‐NbNxOy interface with electronic reconstruction affords near‐optimal hydrogen adsorption energy and enhanced initial H2O adsorption. Furthermore, the terminal O atoms in Mo8O26 clusters cooperate with Nb atoms to promote the initial H2O adsorption, and subsequently reduce the H2O dissociation energy, accelerating the entire HER kinetics. [ABSTRACT FROM AUTHOR]

Developing efficient and robust hydrogen evolution reaction (HER) catalysts for scalable and sustainable hydrogen production through electrochemical water splitting is strategic and challenging. Herein, heterogeneous Mo8O26‐NbNxOy supported on N‐doped graphene (defined as Mo8O26‐NbNxOy/NG) is synthesized by controllable hydrothermal reaction and nitridation process. The O‐exposed Mo8O26 clusters covalently confined on NbNxOy nanodomains provide a distinctive interface configuration and appropriate electronic structure, where fully exposed multiple active sites give excellent HER performance beyond commercial Pt/C catalyst in pH‐universal electrolytes. Theoretical studies reveal that the Mo8O26‐NbNxOy interface with electronic reconstruction affords near‐optimal hydrogen adsorption energy and enhanced initial H2O adsorption. Furthermore, the terminal O atoms in Mo8O26 clusters cooperate with Nb atoms to promote the initial H2O adsorption, and subsequently reduce the H2O dissociation energy, accelerating the entire HER kinetics. [ABSTRACT FROM AUTHOR]

This paper presents a linear-extended-state-observer-based repetitive control (RC) method to enhance the disturbance rejection performance and tracking performance for a nonlinear system with aperiodic uncertainties and disturbances. Both design scenarios, i.e., with and without a detailed mathematical model of the plant, are considered, respectively. The proposed method exhibits the following three attractive features. First, instead of tuning the observer gain via the bandwidth idea by trial and error, available information on the plant model is used to design the observer gain and the state-feedback RC gains. As a result, the disturbance rejection ability is elevated. Second, robust stability and learning efficiency are adjusted preferentially through two tuning parameters, which effectively improve both the transient and steady-state performance. Third, the observer gain and state-feedback RC gains are simultaneously optimized through an optimization algorithm, in which an index is introduced to evaluate the overall system performance. The design procedure of the system is presented in detail. Finally, an application to tracking control of a chuck-workpiece system demonstrates the validity of the proposed method. Comparisons with the conventional RC method, the standard extended-state-observer-based RC method, and a linear active-disturbance-rejection-control-based RC method show that the proposed method can achieve the best disturbance rejection performance. [ABSTRACT FROM AUTHOR]

This paper presents a method to actively reject aperiodic disturbances and to suppress uncertainties in a modified repetitive-control (RC) system, based on an equivalent-input-disturbance (EID) approach. The influences of aperiodic disturbances and uncertainties on the input channel are estimated by an EID estimates and then rejected by incorporating the estimation into a repetitive control law. First, how to construct an EID-based modified repetitive-control system is described, in which a correction is introduced to the amount of the delay of the repetitive controller to enhance the steady-state tracking performance. Next, a linear-matrix-inequality-(LMI)-based stability criterion is derived by employing the Lyapunov functional method. Two tuning parameters introduced in the LMI can manipulate the preferential adjustment of the robust stability and learning efficiency and thus improve both transient and steady-state performances. Then, an optimisation algorithm is presented to produce optimal controller gains. Finally, simulations exhibit the design procedure in detail, and the superiority of the proposed method in this paper is demonstrated through comparisons with some conventional RC and H ∞ RC methods. [ABSTRACT FROM AUTHOR]

This article proposes a distributed model-based cooperative controller to improve voltage synchronization in DC-isolated microgrids that are powered by variable renewable energy sources. Based on the second-order voltage dynamics of dc–dc buck converters, we aim to develop an integral-based linear-quadratic regulator that synchronizes not only the output voltages but also their derivatives. It is necessary not only in reducing voltage ripples and their integrals but also in eliminating steady-state errors. This objective is achieved mainly by introducing a global performance index, which minimizes neighbor synchronization errors, apart from local synchronization errors, and thus transfers the interactions between the dc–dc buck converters from the physical layer to the communication layer. Furthermore, it is demonstrated that the proposed controller ensures global system stability according to the Lyapunov stability theory. Several simulations are made to show the effectiveness of the proposed technique in terms of voltage synchronization and stability, voltage ripple elimination, and voltage convergence speed when input voltage disturbances are present. • Distributed cooperative voltage control for DC-isolated microgrids is proposed. • Interconnected converters represent decomposed agents in the communication layer. • Global performance index minimizes local and neighbor synchronization errors. • Integral-based linear quadratic regulator eliminates dynamic and steady-state errors. • Global stability is proved using Lyapunov approach. [ABSTRACT FROM AUTHOR]

[H3O]3[Heta]4.2 [H2dpp]0.3 [In4Sn16O10S32] ·33H2O is prepared by heating a 10:3:3:3 molar mixture of S, SnCl2·2H2O, In(NO3)3, and 1,3-di(4-pyridyl)propane (dpp) in ethanolamine (eta) (autoclave, 160 °C, 7 d; 25% yield). [ABSTRACT FROM AUTHOR]

By virtue of the structural diversity, electronic tunability and synergetic effect, heterogeneous non‐noble bimetallic catalysts have demonstrated excellent catalytic performance in Fischer‐Tropsch synthesis, biomass conversion and fine chemicals synthesis community. However, the feature of synergetic effect and formation mechanism of bimetallic CoCu NPs under carbothermal conditions still remain to be explored. Herein we report an efficient protocol for fabrication of a representative N‐doped hierarchical porous carbon embedding bimetallic CoCu NPs catalyst. Particularly, the prepared Co0.7Cu0.3@NHPC‐800 catalyst demonstrates unprecedented catalytic activity and chemoselectivity for various nitroaromatics under extremely mild condition (1 atm H2, 30 °C), which is superior to the existing non‐noble metal‐based catalytic systems. It also exhibits excellent activity for hydrolysis of ammonia borane in pure water at room temperature. Furthermore, the possible formation process of bimetallic NPs is firstly brought to light, which could be the key to the nature of CoCu synergistic effect as well as the resultant high activity and selectivity. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of cluster formation control for a networked multi-agent system (MAS) in the simultaneous presence of aperiodic sampling and communication delays. First, to fulfill multiple formation tasks, a group of agents are decomposed into $M$ distinct and nonoverlapping clusters. The agents in each cluster are then driven to achieve a desired formation, whereas the MAS as a whole accomplishes $ M $ cluster formations. Second, by a proper modeling of aperiodic sampling and communication delays, an aperiodic sampled-data cluster formation protocol (CFP) is delicately constructed such that the information exchanges among neighboring agents only occur intermittently at discrete instants of time. Third, a detailed theoretical analysis of cluster formability is carried out and a sufficient and necessary condition is provided such that the system is $M$-cluster formable. Furthermore, a discontinuous Lyapunov functional approach is developed to derive a design criterion on the existence of an admissible sampled-data CFP. Finally, numerical simulations on a team of nonholonomic mobile robots are given to illustrate the effectiveness of the obtained theoretical result. [ABSTRACT FROM AUTHOR]

Abstract: We have successfully synthesized zeolitic imidazolate framework‐8 (ZIF‐8) with controlled sizes and morphology by a facile method in methanol solution. Then the varisized ZIF‐8 coated on the carbon nanotube film (CNTF) and further electrochemically deposited polypyrrole (PPy) to give flexible porous electrodes (noted as PPy/XZIF‐8‐CNTF). Electrochemical dates show that the PPy/lZIF‐8‐CNTF electrode prepared by large size ZIF‐8 exhibits an exceptional areal capacitance (264.8 mF cm−2) at the current density of 1.0 mA cm−2. We also assembled and tested a PPy/lZIF‐8‐CNTF symmetric solid‐state supercapacitor, which shows excellent areal capacitance (143.3 mF cm−2) at the current density of 0.4 mA cm−2. The device also exhibits good cycle stability and flexibility. [ABSTRACT FROM AUTHOR]

We have successfully synthesized the Hong Kong University of Science and Technology-1 (HKUST-1) metal organic framework (MOF)-graphene oxide (GO) hybrids (noted as H-G) onto carbon nanotube film (CNTF) and further electrochemically deposited poly(3,4-ethylenedioxythiophene) (PEDOT) to give a flexible conductive porous electrode (noted as PEDOT/H-G-CNTF), which shows excellent electrochemical performance due to the mesoporous structure of H-G in PEDOT/H-15G-CNTF hybrid. Electrochemical studies show that the PEDOT/H-15G-CNTF exhibits an exceptional areal capacitance of 128 mF cm −2 at 10 mV s −1 than that of PEDOT/HKUST-1-CNTF (81 mF cm −2 ) in a three-electrode system, indicating that the incorporation of GO into the hybrids effectively boosts the capacitive performance of PEDOT/HKUST-1-CNTF. To further explore the capacitive performance of PEDOT/H-15G-CNTF electrode, a symmetric flexible solid-state supercapacitor has also been assembled and tested. The assembled optimum flexible supercapacitor shows superior areal capacitance (37.8 mF cm −2 ) at the scan rate of 5 mV s −1 , and good charge/discharge capability using PVA/H 3 PO 4 gel electrolyte. The volumetric energy density for this device is calculated to be 0.051 mWh cm −3 , with a volumetric power density is 2.1 mW cm −3 at current density of 0.4 mA cm −2 . The device exhibits the excellent electrochemical property and mechanical properties under different bending angles. [ABSTRACT FROM AUTHOR]

A close-packed superstructure consisting of Ti12 and Ti6 in one single crystal is prepared via a solvothermal synthesis. The closest twelve neighboring Ti6 clusters form a distorted cuboctahedron centered with a Ti12 cluster. Such a structure imitates the stacking sequence of a face-centered cubic (FCC) metal. By employing the cuboctahedron as a basic unit, the whole single crystal is re-rendered. [ABSTRACT FROM AUTHOR]

π-Conjugated-group systems are fascinating and have been pursued for nonlinear materials owing to their superior optical and electronic properties, but are so far quite limited. Here, we report a new ultraviolet (UV) nonlinear-optical (NLO) beryllium borate crystal PbBe2B2O6 that manifests an unprecedented π–π interacting BeBO5 group, constructed by interconnected π-conjugated BeO3 and BO3 units. The PbBe2B2O6 crystal has a short UV cutoff wavelength of 249 nm, phase-matching behavior in the whole transmission region from UV to IR light region (249–3166 nm), and remarkably the largest NLO effect (18.5 × KDP) among the π-conjugated UV NLO crystal materials. Theoretical calculation unravels that the highly NLO-active BeBO5 group has strong π–π interactions. This work offers an innovative source of BeO3-participating NLO materials and expands the frontier of NLO research. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Ultrasmall atomically precise thiolate‐protected gold nanoclusters with surface open sites are crucial for practical applications in catalysis. However, there is a lack of systematic studies that unify the kernels‐isomerization, modification of peripheral ligands and electronic effects into one system, as well as their correlation to catalytic performances. In this work, three structurally related Au25nanoclusters with reported star Au25 kernels, Au25‐i‐FTP, Au25‐bi‐FTP, and Au25‐bi‐CHT have been synthesized through two different methods: one‐pot direct reduction and two‐step reduction by using AsPh3 as converter. Their structures and catalytic performance have been comparatively investigated. Au25‐i‐FTP has a classic Au13 core capped by six dimeric RS‐Au‐SR‐Au‐SRs, while Au25‐bi‐FTP and Au25‐bi‐CHT feature typical rod‐shaped biicosahedral geometric kernel. All of the three Au25 clusters were effective catalysts for oxidation of organosilanes, different from conclusions obtained in literature. Especially, the nanorod‐type Au25‐bi‐CHT clusters protected by flexible thiol ligands showed very good catalytic performance in this reaction, the conversion and selectivity were close to 100% within 5 min. The ligand rigidity and electron effects work together to modulate the catalytic properties. The findings inspire us to rethink kernel and ligand effects on catalytic property, and the principle demonstrated here will possibly be widely‐used in high active atom‐precise catalysts modification. [ABSTRACT FROM AUTHOR]

Purple of Cassius is a pigment based on a gold colloid that has been known for hundreds of years. It has had a profound influence on modern nanoscience. But the origin of the small size of the Au nanoparticles (NPs) and their superior stability remains ambiguous. The experiments and characterization studies discussed here confirmed that SnCl2 functioned not only as a reducing agent but also as an effective surface capping agent through bimetallic Au–Sn bonding. This finding expands the types of Au NP stabilizer from traditional organic examples (e.g., thiolate or phosphine) to metallic examples. The formation of a Au–Sn interface also endows Au NPs with excellent activity and separability for the hydration of alkynes to ketones. [ABSTRACT FROM AUTHOR]

This paper investigates the network-based modeling and event-triggered H ∞ reliable control for an offshore structure. First, a network-based model of the offshore structure subject to external wave force and actuator faults is presented. Second, an event-triggering mechanism is proposed such that during the control implementation, only requisite sampled-data is transmitted over networks. Third, an event-triggered H ∞ reliable control problem for the offshore structure is solved by employing the Lyapunov–Krasovskii functional approach, and the desired controller can be derived. It is shown through simulation results that for possible actuator failures, the networked controller is capable of guaranteeing the stability of the offshore structure. In addition, compared with the H ∞ control scheme without network settings, the proposed controller can suppress the vibration of the offshore structure to almost the same level as the H ∞ controller, while the former requires less control cost. Furthermore, under the network-based controller, the communication resources can be saved significantly. [ABSTRACT FROM AUTHOR]

[Display omitted] • The layer formation during dip coating is investigated numerically and experimentally. • New criteria is introduced for determining the demarcations of the layer. • The withdrawal process successively undergoes two regimes. • Models are proposed to predict the heights of the demarcations between different regions. Thus far studies on dip coating focus on the asymptotic layer thickness which is reached only in the lower part of the layer when the withdrawal time is sufficiently long. This work attempts to offer a complete description of the evolution of layer thickness profile with withdrawal time for vertical withdrawal of Newtonian fluids using simulation and the Buckingham π theorem. The results show that over time, the withdrawal process successively undergoes two regimes: (I) an unsteady film region and an unsteady meniscus region and (II) an unsteady film region connected to a steady meniscus region through an unsteady meniscus region. The controlling factors for the two regimes are identified at different values of capillary number and Reynolds number. Models are proposed to predict the heights of the demarcations between different regions. The models agree well with experimental results when the controlling forces are viscous force and gravity. [ABSTRACT FROM AUTHOR]

To guarantee the safety and reliability of drilling riser after emergency disconnection, it is significant to investigate and refrain recoil response of the riser. This paper deals with the problem of Takagi–Sugeno (T-S) fuzzy recoil dynamic modeling and optimal recoil control of nonlinear deepwater drilling riser systems subject to friction resistance of fluid discharge and platform heave motion. First, a nonlinear recoil control model of coupled riser-tensioner is proposed by taking the nonlinear top tension of tensioner into account. Then, a T-S fuzzy dynamic model of the riser-tensioner system is established to approximate the original nonlinear one by using fuzzy modeling scheme. Third, an augmented T-S fuzzy model of riser system is proposed, where the linear exosystem model of friction resistance and platform heave motion is utilized. Fourth, a finite-time fuzzy optimal recoil controller is designed to suppress the recoil response of the riser, the existence and design algorithm of the fuzzy optimal recoil controller are derived. Simulation results demonstrate that the nonlinear recoil model is more accurate than the existing linear one to describe the recoil characteristics of the riser, and the fuzzy optimal recoil controllers are effective to reduce recoil responses and guarantee the safety of the riser significantly. • A nonlinear recoil dynamic model of coupled riser-tensioner is proposed by considering the nonlinear tension. • An augmented T-S fuzzy dynamical model of riser system is developed, where an exosystem of friction resistance is utilized. • Finite-time fuzzy optimal recoil controllers are designed to suppress the recoil response of the riser. • The fuzzy optimal recoil controllers are effective to reduce recoil responses and guarantee the safety of the riser. [ABSTRACT FROM AUTHOR]

This study addresses discrete dynamic modelling and the optimal recoil control problem of deepwater drilling riser systems subject to the friction resistance of fluid discharge and platform heave motion. First, a discrete-time exosystem model for friction resistance of drilling fluid discharge is developed; then, a discrete-time dynamic model of platform heave motion is established. Third, a finite-time discrete optimal recoil controller with feedforward compensation mechanisms was designed. The optimal recoil controller gains can be obtained by iteratively solving discrete equations. The simulation results show that under the discrete feedforward and feedback optimal recoil controller and pure feedback optimal recoil controller, the recoil movements of the riser system are significantly restrained. Moreover, the former is more effective than the latter at resisting the riser recoil response. • A discrete-time exosystem model of the friction resistance induced by drilling fluid discharge on the riser is proposed. • A discrete-time dynamic model of irregular heave motion of drilling platform is established. • A discrete-time recoil control model of the drilling riser system subject to viscous resistance of fluid discharge and platform heave motion is developed. • A finite-timediscrete optimal recoil control scheme with feedforward mechanism is designed to suppress the recoil response of the riser. [ABSTRACT FROM AUTHOR]

Lanthanide metal-organic frameworks (Ln-MOFs) have exhibited remarkable capabilities in color change, luminescence, proton conduction through the strategic modification of metal nodes, organic ligands and channels or pores. By modifying the electron-deficient bipyridinium to contain carboxylic acid moieties and coordinating them with the luninescent Eu3+ ion, a unique and versatile Eu-MOF has been synthesized. Under UV light conditions, the complex shows an obvious color change from colorless to blue, which is due to the formation of viologen radicals after photoinduced electron transfer (PIET) process. As we all know, the changed color is caused by the alteration of absorption intensity, ultimately impacting its luminescence as well. Thus, the bright and strong red fluorescence of this complex is quenched upon continuous UV light irradiation, which may be attributed to intramolecular energy transfer from the excited state of the europium ion to the colored state of the CV ligand. Based on the control of multiple colors of the complex, the designed encryption model can realize multiple anti-counterfeiting of real numbers. In addition, the conductivity of this compound increases significantly after UV illumination, showing excellent photo-modulated proton conductivity. In short, our work has proposed a multifunctional bipyridinium-based Ln-MOF with photochromism, photo-switchable photoluminescence and proton conduction, which offers valuable insights for the creation of versatile switchable materials based on MOFs. [Display omitted] • A novel viologen-based Eu-MOF exhibits reversible photochromism and photo-modulated photoluminescence. • The colored Eu-MOF presents higher proton conductivity after UV irradiation. • The Eu-MOF can be used for multiple anti-counterfeiting encryption of information. [ABSTRACT FROM AUTHOR]

An organic-ligand-free cuprous iodide trinuclear cluster with significant temperature-dependent structural distortion has been synthesized and characterized, which shows thermochromic luminescence originating from a single cluster-centered triplet due to the absence of an organic ligand. This compound also shows interesting reversible temperature dependent phase transition from chiral to centrosymmetric space groups. [ABSTRACT FROM AUTHOR]

Isocyanate and amine functionalized polystyrene (PS) were prepared through the solution copolymerization method with the presence of the intermediate substance 3-isopropenyl-α,α′-dimethylbenzene isocyanate (TMI). The samples with different copolymer composition of functional group were prepared with a range of molecular weights by free radical polymerization, the functional group such as isocyanate, acid amine, and amine group were introduced by appreciate reaction conditions. The isocyanate, acid amine, and amine functionalized polystyrene (PS), denoted as P(St-co-TMI), intermediate product P(St-co-TMITBC) and PS-NH2, respectively. The chemical structure of the samples was characterized by Fourier transform infrared spectroscopy (FT-IR) and1H NMR spectroscopies. The results indicated that the functional groups successfully formed on the side chain of polystyrene. The molecular weight, its distribution, and copolymer composition of functional group were analyzed by gel permeation chromatography combined with FT-IR. The results showed that the copolymer composition increased with the increasing functional monomer content. Viscoelastic behavior in the melt state was investigated and analyzed with dynamic rheology to determine the influence of the interaction of the polymer chain special groups on the rheological properties. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of distributed cooperative longitudinal control of automated vehicle platoons subject to a variety of uncertainties, including unknown engine time lags, external disturbances, measurement noises, and actuator anomaly in follower vehicles as well as unknown leader control. First, a unified framework is proposed for accomplishing resilient vehicle platooning, which empowers longitudinal vehicle state estimation, anomaly signal estimation and compensation, and adaptive platoon controller design to be addressed in a comprehensive way. Second, a novel scalable platooning control design approach is developed to guarantee desired platoon stability and resilience over generic communication topologies and various spacing policies. A salient feature of the approach is that the design procedure does not depend on any global information of the associated topology, and thus preserves essential scalability for large and/or size-varying platoons. Third, it is shown that the proposed longitudinal platooning control approach is promising for performing flexible cooperative maneuvers such as platoon splitting and merging that are beyond the capacity of most existing longitudinal platooning strategies. Finally, simulation results for different platoon maneuvers are elaborated to substantiate the efficacy of the proposed approach. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Hydrogen‐bonded organic networks (HONs) have attracted intense research interest due to their mild synthesis conditions, good solvent processability and strong reproducibility. Most HONs are constructed by electrically neutral organic ligands through intermolecular interactions such as weak hydrogen bonding, π‐π stacking. But there are a few charge‐assisted hydrogen‐bonding networks (CAHONs) constructed by oppositely charged organic components. Under hydrothermal conditions, we successfully synthesized a 3D CAHON (H2CV)(H2BTEC) (1) constructed by H2CV (CV = N,N′‐4,4′‐bipyridine dipropionate) and H4BTEC (H4BTEC = 1,2,4,5‐benzenetetracarboxylic acid) through multiple charge‐assisted hydrogen bonding. Upon soft X‐ray, ultraviolet light or sunlight irradiation under ambient conditions, 1 quickly changes from colorless to blue (1P), and kinetic calculations show that its photochromism meets first‐order dynamics. Interestingly, the colored crystals 1P with long‐lived colored radicals will not fade after being placed for more than two months at room temperature in air, owing to the fact that the photogenerated viologen radicals can be stabilized by the abundant hydrogen bonds, the coplanar pyridinium rings and the slow electron‐hole recombination. Moreover, 1 is a typical direct band gap semiconductor, evidenced by the calculated band gap of 3.24 eV, in agreement with the experimental value of 3.40 eV. In view of its strong colored stability, 1 is designed for distinctive inkless printing. [ABSTRACT FROM AUTHOR]

[Display omitted] • A non-noble-metal plasmonic parabolic membrane with "pearl necklace" structure catalyst is prepared. • Light concentration is realized on basis of plasmonic effect and multiple reflection/absorption effect in parabolic curved surface. • The "pearl necklace" structures induce interface curvature effect for enhancement of water molecules transport process. The high-efficient utilization of sunlight is imperative to inducing a photocatalytic reaction, during which photo-induced electron–hole pairs participate in the redox reaction. The photo-electric effect is the basis for this reaction. The coupled use of sunlight, photo-electric effect and photo-thermal effect, is a significant guidance to realize light concentration, favoring the hydrogen production from water splitting. Here, we prepare an Sn/SnO 2-x @Ni-MOF catalyst, a non-noble-metal plasmonic parabolic membrane with a "pearl necklace" structure. The plasmonic thermal effect and unique parabolic curved surface of this catalyst allow concentrated solar energy and multiple light reflection/absorption to be achieved for the high-efficient utilization of sunlight. Furthermore, the Sn/SnO 2-x @Ni-MOF "pearl necklace" structure also improves photo-generated carriers' separation-transfer process by internal Schottky junction between Sn and SnO 2-x /Ni-MOF, and helps accelerate water molecules transport based on the interface curvature effect. As a result, a competent rate of 8800 μmol h−1 g−1 with apparent quantum yields of 22.1 % and 16.2 % is achieved at wavelengths of 380 and 420 nm, respectively, providing a promising route for utilizing hydrogen energy. [ABSTRACT FROM AUTHOR]

1 The dip coating of yield stress fluids was simulated at Bingham number below 1. 2 The effects of individual physical parameters and the lifting speed on the flow inside the bath were studied. 3 The relationship between flow region, velocity and shear stress of fluids in the bath were established. 4 The dimensionless film thickness can be well described by the Bingham number. The literature has treated the dip coating of yield stress fluids with the Bingham number (B i = τ c / K γ ˙ n , where τ c , K , γ ˙ and n are the yield stress, consistency factor, shear rate and power-law exponent, respectively.) being larger than 1, and has ignored the influence of shear-dependent component (K γ ˙ n). This work simulated the dip-coating process for various simple yield stress fluids with Bi numbers below 1, and showed the importance of yield stress and shear-dependent component for the hydrodynamics inside the bath as well as the film thickness. The yielded-unyielded boundaries as well as the profiles of flow velocity and shear stress were theoretically determined under final steady state. The main flow characteristics of drainage in the meniscus were captured. Under the negligible effect of surface tension on the film coating, a semi-empirical model of film thickness considering drainage effect is proposed with good prediction performance. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: The direct catalytic oxidative coupling of amines is one of the attracting methods for the synthesis of a variety of pharmaceutical or industrial needed imines. Numerous earth‐abundant manganese based salts, oxides, and complexes have been applied in this reaction. However, these compounds suffered from difficult separation, large catalyst loading, complicated reactivation or indeterminate activity. Considering the facts that metal‐organic frameworks (MOFs) with crystalline structure, precise composition, and enormous surface area have superior performance in heterogeneous catalytic reactions, herein, we introduced Mn into [Fe3(μ3‐O)(CH3COO)6], one of the precursors for the preparation of stable MOFs, and got [Fe2Mn(μ3‐O)(CH3COO)6] cluster. After ligand replacement with biphenyl‐3,4',5‐tricarboxylic acid (BPTC), heterometallic cluster‐based [Fe2Mn(μ3‐O)(BPTC)2(DMF)2(H2O)] (1) was obtained. As expected, 1 is stable and able to catalyze the homo‐ or cross‐coupling of amines effectively and selectively with 0.9 mol% catalyst loading at room temperature. Control experiments indicated that the catalytic activity of 1 mainly stems from Mn sites and that Fe synergistically contributes to the stability. Additionally, 1 is recyclable and can be reused easily for at least 8 runs without obvious decrease in catalytic ability. To our knowledge, 1 should be the first heterometallic cluster‐based MOF with defined structure suitable for the synthesis of diverse imines from oxidative coupling of amines under mild conditions, which may shed light on the easy preparation of effective heterogeneous catalysts for organic synthesis. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with robust integral sliding mode control for an offshore steel jacket platforms subject to nonlinear wave-induced force and parameter perturbations. A robust integral sliding mode controller is designed to stabilize the dynamic model of the offshore steel jacket platform. It is shown through simulation results that the robust integral sliding mode control scheme can reduce the internal oscillations of the offshore steel jacket platform dramatically; and the performance of the offshore steel jacket platform under the robust integral sliding mode control scheme is better than the ones under the nonlinear control scheme and the dynamic output feedback control scheme. [Copyright &y& Elsevier]

A series of isostructural metal-carboxylate frameworks [Me2NH2][M2(bptc)(μ3-OH)(H2O)2] (H4bptc = 3,3′,4,4′-biphenyltetracarboxylic acid, M = Co, Co0.83Ni0.17, Co0.55Ni0.45, Co0.13Ni0.87, and Ni for 1–5, respectively) have been synthesized, which feature (4,8)-connected scu topological anionic frameworks constructed by a butterfly-like [M4(OH)2(RCO2)8] cluster and have three-dimensional (3D) channels filled by in situ generated [Me2NH2]+ cations. Flame atomic absorption spectroscopy (FAAS), scanning electron microscope energy-disperse X-ray spectroscopy (SEM-EDS), infrared spectroscopy (IR), Raman spectroscopy, and powder X-ray diffraction (PXRD) measurements reveal that 1 can selectively exchange alkali metal cations. Magnetic properties display that monometallic 1 and 5 are characteristic of a antiferromagnet and a ferromagnet, respectively. Incorporation of Co and Ni into the system produced heterometallic compounds 2, 3, and 4. Compound 2 with a very low ratio of Ni to Co shows antiferromagnetic behavior similar to 1, while compounds 3 and 4 with a large ratio of Ni to Co are characteristic of ferrimagnetic-like behavior. This work demonstrates that magnetic tuning from antiferromagnetic, ferrimagnetic-like, to ferromagnetic behaviors can be achieved by heterometallic substitution in isostructural magnetic frameworks. A series of isostructural metal-carboxylate frameworks have been synthesized, which feature a butterfly-like [M4(OH)2(RCO2)8] cluster based on (4,8)-connected scu topological anionic networks with 3D channels filled by [Me2NH2]+ cations. The color of these compounds regularly varies from purple, red, gray, greenish, to green, and their magnetic behaviors can be tuned from antiferromagnet, ferrimagnetic-like, to ferromagnet. Selective cation-exchange with alkali metals has been observed in the work. [ABSTRACT FROM AUTHOR]

Abstract: Hydrothermal reaction of Zn/Cd salts, NaN3 and 4-cyanobenzoic acid via in situ [2+3] cycloaddition generated two blue-green photoluminescent coordination polymers [Zn(cptta)(H2O)] (1) and [Cd(cptta)(H2O)] (2) (H2cptta=5-(4′-carboxy-phenyl)tetrazole). When only metal ions are considered as nodes, 1 shows rare 5-connected Shubnikov plane topological type and 2 has unprecedented 10-connected {312.424.59} topological type. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of copper(II) chloride with 2-hydroxypyrimidine generated double salt of [Cu2Cl(μ4-pymo)] (1) (Hpymo=hydroxylpyrimidine) while hydrothermal treatment of CuCl2, NaN3 and acetonitrile resulted in double salt of [Cu2(mtta)Cl] (2) (Hmtta=5-methyltetrazole) in which in situ [2+3] cycloaddition reactions of acetonitrile with azide formed mtta ligand. X-ray single crystal structural analyses revealed that 1 shows a two-dimensional layer formed by fusion of one-dimensional structural motifs. The two-dimensional layers in 1 are held together by C–H⋯Cl hydrogen bonds to form three-dimensional supramolecular array. Compound 2 has a three-dimensional framework constructed from ribbons and [Cu8Cl4]4+ units. Uncommon coordination modes of μ4-1,2κO:3κN:4κN′ pymo and μ4-Cl (Cl at the apex of a Cu4Cl square pyramid) in 1 and μ4-η1:η1:η1:η1 mtta in 2 were also observed. The short Cu(I)⋯Cu(I) distances were found in 1 and 2, indicating the existence of Cu(I)⋯Cu(I) interactions. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of CuBr2, 4,4′-bipyridine and ethanol/methanol generated two copper (I) bromide complexes with in situ alkylated 4,4′-bipyridium, namely [C14H18N2][Cu5Br7] (1) and [C12H14N2][Cu4Br6] (2). The structure of 1 consists of chains and N,N′-diethyl-4,4′-bipyridinium. The underlying structural motif in of 1 is the Cu5Br capped square pyramid, which is different from the Cu5Br2 pentagonal bipyramidal structural motif in various documented anions. The in 1 contains untypical μ5-bromide, with which five copper atoms forms a capped square pyramid rather than a pentagonal pyramid as predicted by Subramanian and Hoffmann. Compound 2 is isostructural with [C12H14N2][Cu4Cl6] reported by Willett, and consists of chains and N,N′-dimethyl-4,4′-bipyridinium. The chain is composed of alternating Cu6Br6 and Cu2Br6 units. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of molybdenum oxide and copper(II) source in the presence of 4,4′-bipyridine (4,4′-bpy) afforded three-dimensional covalent framework [CuII(4,4′-bpy)(MoO4)] (1), while reaction with 1,4-diazoniabicyclo[2,2,2]octane (DABCO) in place of 4,4′-bpy and addition of metal molybdenum resulted in one-dimensional chain-like compound . The copper in 1 is divalent and approximately shows trigonal bipyramidal geometry, while in 2 is monovalent and approximately shows T-shaped geometry. The structure of 1 has a three-dimensional pillar-layered framework constructed from bimetallic {CuMoO4} layers bridged by bifunctional ligand 4,4′-bpy. Interestingly, the {CuMoO4} layer in 1 consists of 16-membered {Cu4Mo4O8} rings and 8-membered {Cu2Mo2O4} rings, different from other reported {CuMoO4} layers. The structure of 2 consists a one-dimensional chain that is attached by peripheral {Cu(HDABCO)}2+ units. The chain is constructed from octamolybdates through common corners. [Copyright &y& Elsevier]

This paper presents an output‐feedback repetitive control method for a class of systems with nonlinearities, unknown state‐dependent uncertainties, and external disturbances. An additive‐state‐decomposition approach is used to decompose the system under study into a primary linear periodic system in charge of repetitive‐control tracking task and a secondary linearized system in charge of robustly stabilization task. Such a treatment not only significantly simplifies system analysis and controller design, but also provides an effective method to cope with the intrinsic constraints between tracking and disturbance rejection. Another attractive point lies in two aspects. On one hand, a periodic term from the nonlinearity in the plant is extracted to be treated in the primary system and the known plant information is used to design controller parameters, which greatly improves the disturbance rejection ability of the system. On the other hand, repetitive control gain, feedback control gain, and the observer gain are optimized through an optimization algorithm by introducing an index to evaluate the overall system performance. System stability criteria and design procedure are developed. Finally, a case study on the tracking control of a chuck‐piece system demonstrates the validity of the proposed method. Comparisons with some existing methods show that the proposed method achieves better performances in both signal tracking and disturbance rejection. [ABSTRACT FROM AUTHOR]

The introduction of chirality into organic–inorganic hybrid perovskites (OIHPs) is expected to achieve excellent photoelectric and nonlinear materials related to circular dichroism. Owing to the existence of asymmetric center and intrinsic chirality in the chiral OIHPs, the different efficiencies of second harmonic generation (SHG) signal occurs when the circularly polarized light (CPL) with different phases passes through the chiral crystal, which is defined as second harmonic generation circular dichroism (SHG‐CD). Here, the SHG‐CD effect is developed in bulk single crystals of chiral one‐dimensional (1D) [(R/S)‐3‐aminopiperidine]PbI4. It is the first time that CPL is distinguished using chirality‐dependent SHG‐CD effect in OIHPs bulk single crystals. Such SHG‐CD technology extends the detection range to near infrared region (NIR). In this way, the anisotropy factor (gSHG‐CD) through SHG‐CD signal is as high as 0.21. [ABSTRACT FROM AUTHOR]

The introduction of chirality into organic–inorganic hybrid perovskites (OIHPs) is expected to achieve excellent photoelectric and nonlinear materials related to circular dichroism. Owing to the existence of asymmetric center and intrinsic chirality in the chiral OIHPs, the different efficiencies of second harmonic generation (SHG) signal occurs when the circularly polarized light (CPL) with different phases passes through the chiral crystal, which is defined as second harmonic generation circular dichroism (SHG‐CD). Here, the SHG‐CD effect is developed in bulk single crystals of chiral one‐dimensional (1D) [(R/S)‐3‐aminopiperidine]PbI4. It is the first time that CPL is distinguished using chirality‐dependent SHG‐CD effect in OIHPs bulk single crystals. Such SHG‐CD technology extends the detection range to near infrared region (NIR). In this way, the anisotropy factor (gSHG‐CD) through SHG‐CD signal is as high as 0.21. [ABSTRACT FROM AUTHOR]

A facile and hard template-assisted spatial confinement strategy was presented to prepare Co SSCs@NG-800-50 catalyst with ultra-high loading of 10.26 wt%, which displays excellent transfer hydrogenation of nitrobenzene with >99% conversion and 96.3% aniline selectivity as well as other nitroaromatics in the presence of HCOOH. [Display omitted] • Co single-site catalysts are fabricated via one-step pyrolysis of DCDA and CoPc mixture. • Co SSCs content reaches 10.26 wt%, which is close to the parent CoPc molecule (10.31 wt%). • SACTEM and XAFS analysis revealed that the Co species are present as CoN 3 structure. • CoN 3 site exhibited superior performance for transfer hydrogenation of nitroaromatics. • DFT calculations disclosed the reaction mechanism of the tandem catalysis. Atomically dispersed non-noble metal single-site catalysts (SSCs) provide a promising approach to meet the catalytic requirements that traditional nanoparticles cannot accomplish. However, they often suffer from formidable challenges of cumbersome route, unmanageable loading, inevitable burial of active site and insufficient stability. Herein, we present a facile and hard template-assisted spatial confinement strategy to prepare Co SSCs embedded in N-doped graphene-like carbon (NG) with ultra-high loading of 10.26 wt%, which is close to the parent CoPc (10.31 wt%). Furthermore, the microstructure, surface area and Co loading in the titled catalysts can be easily manipulated via altering the synthesis parameters. The optimized Co SSCs@NG-800-50 catalyst shows excellent transfer hydrogenation of nitrobenzene with > 99% conversion and 96.3% aniline selectivity as well as good universality for various nitroaromatics in the presence of HCOOH. DFT calculations in combination with elaborate experiments unveil that the active H is firstly generated by the dissociation of C-H bond rather than the recognized O-H bond in HCOOH, then it is used for the hydrogenation of nitroaromatics on CoN 3 site in Co SSCs@NG-800-50 catalyst, revealing the reaction mechanism of the tandem catalysis. This report paves a novel route to design and construct efficient and high-loading non-noble metal SSCs. [ABSTRACT FROM AUTHOR]