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The convergence of sensing, computing, communication and control elements drives the traditional point-to-point control systems towards networked control systems. Sampled-data control systems, which focus on the significant interplay between sampling and control, play a critical role in modern networked control systems, including intelligent transportation systems, smart grids, and advanced manufacturing systems. This paper presents a survey of methods and trends in non-uniform sampled-data control systems, where sampling and control actions are performed in an aperiodic manner. First, some fundamental issues of both continuous- and discrete-time sampled-data control systems are discussed. Next, main methods in both continuous-time and discrete-time domains are elaborated, respectively. Then, event-triggered sampling, under which sampling is executed only when the system needs attention, is examined. Typical triggering mechanisms in the existing literature are reviewed and classified into four types according to different threshold functions. Furthermore, two applications in terms of automated vehicle platoons and islanded microgrids are provided to demonstrate that sampled-data control methods are capable to support relevant practical application scenarios. Finally, several challenging issues are envisioned to direct future research. [ABSTRACT FROM AUTHOR]

This article investigates $H_{\infty }$ synchronization of delayed neural networks under a receding horizon scheme, where two types of interval time-varying delays are considered according to whether the lower bound of the delay derivative is known or not. Note that a receding horizon synchronization law can be regarded as an optimization solution at each timeslot to a minimaxization problem related closely with a certain cost functional. In this article, two cost functionals with some delay-dependent matrices are introduced, respectively, for the two types of time delays. In order to obtain less conservative conditions, a novel inequality on quadratic polynomial functions is established, which includes some existing ones as its special cases. Based on the novel inequality, two sufficient conditions are derived to design the terminal weighting matrices of the cost functionals such that the resulting synchronization error system can be stabilized with a prescribed infinite horizon $H_{\infty }$ performance level. Finally, three numerical examples are used to demonstrate the validity of the proposed results. [ABSTRACT FROM AUTHOR]

Ligand‐protected heterometallic nanoclusters in contrast to homo‐metal counterparts show more broad applications due to the synergistic effect of hetero‐metals but their controllable syntheses remain a challenge. Among heterometallic nanoclusters, monovalent Ag‐Cu compounds are rarely explored due to much difference of Ag(I) and Cu(I) such as atom radius, coordination habits, and redox potential. Encouraged by copper‐catalyzed alkyne‐azide cycloaddition (CuAAC) reaction, comproportionation reaction of Cu(II)X2 and Cu(0) in the presence of (PhC≡CAg)n complex and molybdate generated a core‐shell peanut‐shaped 66‐nuclear Ag(I)‐Cu(I) heterometallic nanocluster, [(Mo4O16)2@Cu12Ag54(PhC≡C)50] (referred to as Ag54Cu12). The structure and composition of Ag‐Cu heterometallic nanocluster are fully characterized. X‐ray single crystal diffraction reveals that Ag54Cu12 has a peanut‐shaped silver(I)/copper(I) heterometallic nanocage protected by fifty phenylacetylene ligands in µ3–modes and encapsulated two mutually twisted tetramolybdates. Heterometallic nanocage contains a 54‐Ag‐atom outer ellipsoid silver cage decorated by 12 copper inside wall. Nanosized Ag54Cu12 is a n‐type narrow‐band‐gap semiconductor with a good photocurrent response. Preliminary experiments demonstrates that Ag54Cu12 itself and activated carbon supported Ag54Cu12/C are effective catalysts for 1,3‐dipole cycloaddition between alkynes and azides at ambient conditions. The work provides not only a new synthetic route toward Ag(I)‐Cu(I) nanoclusters but also an important heterometallic intermediate in CuAAC catalytic reaction. [ABSTRACT FROM AUTHOR]

Recent research has shown that one can obtain a less conservative stability criterion for a continuous-time linear system with a time-varying delay by introducing a Lyapunov-Krasovskii functional with a polynomial matrix on the time-varying delay. This paper aims at analysing the stability of discrete-time linear systems with time-varying delays by introducing a delay-square-dependent Lyapunov functional. A novel convex method is presented to formulate a less conservative stability criterion, which is demonstrated through numerical simulation. Moreover, it is also shown that, if the polynomial inequality method is employed, the resultant stability criterion is inapplicable due to its extremely high numerical complexity. [ABSTRACT FROM AUTHOR]

A correction to this paper has been published: https://doi.org/10.1007/s00280-021-04287-1 [ABSTRACT FROM AUTHOR]

This paper is concerned with the H ∞ performance of discrete-time networked systems subject to network-induced delays and malicious packet dropouts. First, the introduction of a data packet processor enables us to calculate both network-induced delays and the number of consecutive malicious packet dropouts explicitly. Second, a novel Lyapunov functional is constructed, whose forward difference along with the trajectory of the closed-loop system is estimated as a quartic polynomial. A class of necessary and sufficient conditions on such an inequality are established by using the Finsler lemma. By employing the Lyapunov method, a bounded real condition is formulated, which depends on the upper bound of network-induced delays and the maximum number of consecutive malicious packet dropouts. Therefore, their effects on H ∞ performance can be investigated simultaneously. Finally, the effectiveness of the proposed method is shown through an inverted pendulum system. [ABSTRACT FROM AUTHOR]

Hybrid metal halides (HMHs) have emerged as a promising platform for optically functional crystalline materials, but it is extremely challenging to thoroughly elucidate the electron transition coupled to additional ligand emission. Herein, to discover sequences of lead‐free HMHs with distinct optically active metal cations are aimed, that is, Sb3+ (5s2) with the lone‐pair electron configuration and In3+ (4d10) with the fully‐filled electron configuration. (Me2NH2)4MCl6·Cl (Me = −CH3, M = Sb, In) exhibits the superior temperature/component‐dependent luminescence behaviors resulting from the competition transition between triplet‐states (Tn‐S0) self‐trapped excitons (STEs) of inorganic units and singlet‐state (S1‐S0) of organic cations, which is manipulated by the optical activity levels of [SbCl6]3− and [InCl6]3−. The bonding differences between Sb3+/In3+ and Cl− in terms of electronic excitation and hybridization are emphasized, and the different electron‐transition mechanisms are established according to the PL spectra at the extreme temperature of 5 to 305 K and theoretical calculations. By fine‐tuning the B‐site Sb3+/In3+ alloying, the photoluminescence quantum yield (PLQY = 81.5%) and stability are optimized at 20% alloying of Sb3+. This research sheds light on the rules governing PL behaviors of HMHs, as well as exploring the optical‐functional application of aviation temperature sensors and access‐control systems. [ABSTRACT FROM AUTHOR]

Hybrid ns2 metal halides have attracted extensive attention due to the unique photophysical behavior. However, the reasonable improvement of photoluminescence efficiency by accurate structural modulation remains a great challenge. Herein, two kind of antimony halides with formulae as (S)/(R)‐[C6H16N2]3[SbCl5]2·2Cl ((S)/(R)‐1·2Cl) and (S)/(R)‐[C6H16N2]2[SbCl5]2 ((S)/(R)‐2) ([C6H16N2]2+ = 1,2‐Diaminocyclohexane) are developed, in which 0D [Sb4Cl20]8− clusters and 1D infinite [SbCl5]n2n− polyanion chains are adopted, respectively. The stoichiometric tunability enables metastable (S)/(R)‐1·2Cl being transformed to dynamic stable (S)/(R)‐2. All compounds contain a large number of Sb─Cl secondary bonds because of the strong chemical activity of 5s2 electrons. The obtained compounds exhibit broadband orange‐light emission, while photoluminescence quantum yield of (S)/(R)‐2 is significantly enhanced to ≈76% due mainly to the generation of more localized electrons onto 1D chains. Experimental and computational results reveal that efficient broadband emission derives from the synergistic emission of singlet and triplet states, where the presence of shallow trap energy levels leads to anti‐thermal quenching behavior. Furthermore, the highly efficient photoluminescence property allows (S)‐2 to become excellent down‐conversion phosphor for white‐light emitting diode. This work proves that exploring structure‐property relationship in hybrid systems is helpful in promoting the rapid development of high‐performance broadband emission metal halides. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The photocatalytic oxidative coupling of thiols is one of the most popular methods to synthesize the disulfides. Triphenylamine and its derivatives (TPAs) are promising for the above reaction, but suffer from the easy polymerization and difficult separation. To overcome these obstacles while controlling the photogenerated electrons transfer directly to target substrates, herein, we constructed one TPA‐based metal‐organic framework (MOF), (Me2NH2)[Sr(TCBPA)]·DMA·3H2O (1), by direct self‐assembly of tris(4′‐carboxybiphenyl)amine (H3TCBPA) and photoredox inert strontium ion (Sr2+). DFT calculations revealed that the valence band maximum (VBM) and the conduction band minimum (CBM) are mainly located on TCBPA3–, successfully inhibiting the undesirable electron migration to metal nodes. Experimental results indicated that 1 displays superior performance than homogeneous H3TCBPA, which may result from the abundant π···π and C—H···π interactions between the well‐arranged TCBPA3– and the build‐in electric field between the anionic framework and the Me2NH2+. This work highlights that immobilizing TPAs into MOFs is one promising approach to designing heterogeneous photocatalysts for the synthesis of disulfides by oxidative coupling of thiols. [ABSTRACT FROM AUTHOR]

The thermal design of natural convection heat sinks is critical to the heat management of electronic devices. In this paper, topology optimization (TO) with a new parameter advancing scheme is employed to study the effect of the heating power, heat source size, allowed volume and material thermal conductivity on the optimized design of natural convection heat sinks. Except for the heating power, the other three factors also play an important role on the optimization results. For the small heating power, TO predicts the tree-like heat sink with many secondary-branches to improve heat conduction, but the specific structure is highly dependent on the heat source size, allowed volume and material thermal conductivity. For the large heating power, TO prefers to produce the taper-like heat sink where the tiny branches fade away to adapt to the strong flow, and the influences of the other three factors are reduced. However, two primary branches that connect the heat source and top corners of the design domain always exist, indicating that they are the most effective ways to improve heat transfer. This work has highlighted the impact of different parameters in TO of natural convection heat sinks and provides a more in-depth understanding of the design guidelines. [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]

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 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]

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]

[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]

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]

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]

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]

In this paper, the asymptotical synchronization of fractional-order complex neural networks with non-delayed and delayed couplings is investigated. By employing the Kronecker product technique and weighted norm, two Lyapunov functions are constructed. Based on the fractional-order Lyapunov direct method and Kronecker product method, together with the Laplace transform and the comparison principle, several novel sufficient conditions on synchronization of fractional-order complex neural networks with non-delayed and delayed couplings, respectively, are proposed. Finally, three numerical examples are given to show the effectiveness of our proposed theoretical results and the difference between our main result and some existing results in the literature. [ABSTRACT FROM AUTHOR]

This paper deals with the adaptive learning based recoil suppression control problem of deepwater drilling riser systems subject to parametric perturbations, platform heave motion, and friction resistance force of drilling fluid discharge. First, a stochastic configuration network based approximator is presented to predict the friction resistance force of drilling fluid discharge. Then, model reference adaptive learning recoil controllers are developed for the drilling riser system, and the existence condition and supporting algorithm are provided. Simulation results show that: (i) the designed stochastic configuration network approximator is efficient to predict the friction resistance of drilling fluid discharge on the riser; (ii) the presented model reference adaptive learning recoil controllers are effective to restrain the recoil response of the riser; (iii) compared with the existing recoil controllers, which are all based on the exact dynamic recoil control models, the model reference adaptive learning recoil controllers proposed in this paper are no longer constrained by the accuracy of recoil model; (iv) the model reference adaptive learning recoil controllers are more robust than the existing ones to the unmodeled dynamics, systematic uncertainty, and parametric perturbations, and have better transient performance of system thereby guaranteeing the safety of the drilling riser systems effectively. • A learning-based friction force predictor of drilling fluid discharge is designed. • Model reference adaptive learning recoil controllers are proposed for riser systems. • Adaptive recoil controllers are robust to unmodeled system dynamics and disturbances. [ABSTRACT FROM AUTHOR]

In the dangerous ocean situations, the deepwater drilling riser needs evacuate emergently to guarantee the safety of the structures. The bottom equipment of the lower marine riser package should be disconnected from the blowout preventer timely. In this case, the recoil response of the riser occurs, which may lead to potential safety risks of the structure. This paper deals with the recoil suppression control problem of a deepwater drilling riser system via static output feedback recoil control scheme with memory. First, for the riser-tensioner system subject to the friction resistance of drilling discharge and the heave motion of platform, a static output feedback recoil controller with both current and delayed output signals of the system is proposed. Then, the existence conditions and design algorithm of the static output feedback recoil controller are derived. The gain matrices of the recoil controller can be obtained by solving linear matrices inequalities. It is found through simulation results that (i) the static output feedback recoil controllers with and without memory are effective to reduce the recoil responses of the riser; and (ii) to design the applicable output feedback recoil controllers, the displacement and velocity signals of the first mass block of the riser are required, and specifically, the velocity signal of the first mass block is indispensable; and (iii) the output feedback recoil controllers with memory provide more implementation options, and practically better than the ones without memory and some existing full state feedback recoil controllers. • Static output feedback recoil controllers with memory (OFRCMs) are designed for a drilling riser-tensioner system. • To design feasible OFRCMs, velocity signal of the first mass block of the riser-tensioner system is indispensable. • The designed OFRCMs provide more implementation options and practically better than existing recoil controllers. [ABSTRACT FROM AUTHOR]

The construction of C(sp3)-C(sp3) bonds by different C(sp3) radicals coupling reactions is still unexplored due to the high bond dissociation energy of C(sp3)-H bond and the difficulty for selective generating of C(sp3) radical. Benefiting from the precisely regulating for band structures of Hf-PCN-224(M), the β-carbonyl C(sp3)-H bonds are effectively oxidized by photo-generated holes to affording C(sp3) radicals in this work. C(sp3)-C(sp3) and C(sp3)-O bonds are constructed by tandem radical-radical cross-coupling, hydrogen atom transfer (HAT), and radical-radical cross-coupling between two C(sp3)-H bonds, enabling an effective C 3 -difunctionalization of indolin-2-ones under photo-thermo synergetic catalysis on Hf-PCN-224(Cu). Significantly, OH serves as triple roles: introduced hydroxyl group in situ, HAT abstractor and α-heteroatom for secondary activating C(sp3)-H bonds. Control experiments, EPR spectroscopy and DFT calculation provide insight into the tandem radicals cross-coupling mechanism. This operable strategy opens up a door for the difunctionalization of C(sp3)-H bonds in heterogeneous photoredox manner. [Display omitted] • activation and difunctionalization of C(sp3)-H bond by heterogeneous photoredox. • selective C(sp3) radicals generation by h+ oxidation based tuning band structure. • tandem •C indolin -•OH cross-coupling/HAT/•C indolin-O -•C quinoline cross-coupling. • triple roles of OH. • unapplied sacrificial electron donors and high turnover frequency value. [ABSTRACT FROM AUTHOR]

This paper deals with the observer-based dynamic optimal recoil controller design of a deepwater drilling riser system subject to friction force of fluid discharge and platform heave motion. First, by using exponential and polynomial functions conjunctively, a novel nonlinear computational model of the friction force is presented. Then, a linear system model is developed to describe dynamic characteristics of the friction force. Third, by using feedforward mechanisms and internal model principle jointly, a dynamic optimal recoil control scheme is proposed for the riser, where the feedforward mechanism is designed to compensate the friction force of fluid discharge, and the internal model principle is introduced to reject platform heave motion. The conditions of existence and uniqueness of a dynamic optimal recoil controller of the riser are developed. Fourth, a friction force observer is designed to solve the physically realizable problem of the recoil controller. Simulation results show that under the observer-based dynamic optimal recoil controller, the recoil of the riser can be attenuated significantly, and zero steady state errors of the riser can be guaranteed. In addition, from the perspective of achieving steady performance of the riser, the designed dynamic optimal recoil control scheme outperforms existing linear quadratic optimal control schemes. • An exponential-polynomial type friction force model of fluid discharge is developed.. • An augmented coupling riser-tensioner recoil control system is presented. • An observer-based dynamic optimal recoil controller with feedforward is designed. • The recoil controller can guarantee a zero steady–state error of the riser system. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of dynamic modeling and the optimal recoil control of a deepwater drilling riser system subject to the friction force of drilling fluid discharge. First, based on the whole fluid column model of the friction force and the curve fitting method, a linear exosystem model is established to describe the dynamic properties of the friction force, where the friction force of drilling fluid discharge is formulated as an output of the exosystem. Then a recoil dynamic model of the drilling riser in the event of emergency disconnection is proposed to describe the recoil response characteristics. Third, an optimal recoil control scheme with discharge feedforward compensation is developed to refrain the recoil response of the riser system. The existence and uniqueness conditions of the optimal recoil controller are derived, and the gain matrices of the controller can be obtained by solving an algebraic Riccati equation and a Sylvester equation. It is found through simulation results that the proposed optimal recoil controller with feedforward compensation can reduce recoil response of the riser system significantly. Moreover, the proposed controller outperforms the existing optimal recoil control scheme in the sense of the quadratic performance indices of the riser system. • An exosystem model of fluid discharge friction resistance on the riser is developed. • An optimal recoil control scheme with feedforward mechanisms is proposed. • The proposed scheme is effective to suppress recoil response of the riser system. [ABSTRACT FROM AUTHOR]

• Oxidation behaviors for oxidized and pyrolytic cokes were contrastively estimated. • Coke unique peak at 1590 cm−1 was due to C = C bands in highly conjugated structures. • Air atmosphere had considerable effect on the evolution of C/N/S- functional groups. • Complex physical and chemical reactions in LTO process promoted coke formation. Fundamental knowledge on the evolution of low temperature oxidized coke was a prerequisite towards a deep understanding of coke deposition and subsequent combustion of ultra-heavy oils during in-situ combustion (ISC) process. This study investigated the structural characterization (oxidation behavior, elemental composition, functional groups, and morphology) and elucidated evolution mechanism of cokes generated from the low temperature oxidation/pyrolysis of the ultra-heavy oil during ISC process. The results shown that, compared with pyrolytic coke, the intermediate groups of C-O/C-OH (1260–1060 cm−1) were further oxidized into C = O (1850–1650 cm−1) groups and finally converted into C = C groups ("coke peak", 1590 cm−1) in highly conjugated aromatic structures for oxidized cokes. Besides, the oxidized coking condition would result in a higher degree of substitution (γCH Ar1 , γCH Ar4) of aromatic rings (900–700 cm−1) and promote the evolution of N- and S- functional groups. Although >78 % of C 1 s belonged to the graphitic carbon for four cokes, morphologies of oxidized cokes were relatively coarse with much looser distribution. In addition, the corresponding enthalpies were in the order coke LTO3 (25.51 kJ·g−1) > coke LTP (24.22 kJ·g−1) > coke LTO2 (23.23 kJ·g−1) > coke LTO1 (17.45 kJ·g−1), indicating a considerable contribution of low temperature oxidation reactions on derived coke morphology, oxidizability and exothermicity, which contained complicated and crucial dehydrogenation, crosslinking and polymerization reactions to accelerate coke evolution. [ABSTRACT FROM AUTHOR]

• Na 2 Ca 17 A l2 (PO 4) 14 features a 3D Ca-cluster-constructed framework by the stacking of Ca6O36 and (Ca/Na)3O19 clusters. • Na 2 Ca 17 Al 2 (PO 4) 14 exhibits a short UV absorption edge below 190 nm and strong phase-matching NLO response of 0.9 × KDP. • Millimetre-crystals are grown. • Optical properties are mainly determined by the Ca−O groups. Na 2 Ca 17 Al 2 (PO 4) 14 features a 3D Ca-cluster-constructed framework, exhibiting a short UV absorption edge below 190 nm and phase-matching behavior with strong NLO effect of 0.9 × KDP. First-principles calculations indicate that the optical properties derive primarily from the Ca−O groups. [Display omitted] Nonlinear-optical (NLO) metal aluminium phosphate crystal materials with deep-ultraviolet (DUV) transparent ability remain greatly unexplored. Herein, mixed alkali/alkaline-earth metal aluminium phosphate DUV NLO crystal Na 2 Ca 17 Al 2 (PO 4) 14 was successfully synthesized through the high-temperature molten technology. Na 2 Ca 17 Al 2 (PO 4) 14 features a 3D Ca-cluster-constructed framework by the stacking of Ca 6 O 36 and (Ca/Na) 3 O 19 clusters, which is filled by isolated Al(PO 4) 6 clusters and isolated PO 4 tetrahedra. Na 2 Ca 17 Al 2 (PO 4) 14 exhibits a short UV absorption edge below 190 nm, phase-matching behavior with strong NLO effect of 0.9 × KDP, high thermal stability. First-principles calculations indicate that the optical properties of Na 2 Ca 17 Al 2 (PO 4) 14 derive primarily from the Ca−O groups, rather than Al–O and P–O traditional groups. The work may further promote the exploration of new DUV NLO aluminium phosphate crystal materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The N-species in NG-T can be fine-tuned by the pyrolysis conditions, facilitating differentiating functions among different N-species. • The C atoms next to the graphitic-N species serves as active sites for efficient CO 2 conversion. • The optimized catalyst is capable of achieving a selectivity of 95.0 % in converting CO 2 into CO, comparable to the metal-based catalysts. For metal-free nitrogen(N)-doped carbon catalysts, diverse N-bearing species embedded in the carbon framework are generally regarded as chemical promoters that can upgrade their catalytic performance for CO 2 electroreduction reaction (CO 2 RR). However, it is still a controversy as to which N species plays a dominant role. Herein, a type of large surface area (371 m2/g), N-rich (11.0 wt%) graphene-like carbon electrocatalyst (NG-1000) is fabricated via facile pyrolysis from a precursor composite of dicyandiamide and phthalocyanine. The N-species in the NG-T (T = 700–1000 °C) can be fine-tuned, thus facilitating differentiating functions of the various N-species. Based on the comprehensive analysis of original Pc/CNTs and NG-T catalysts, we identified that the C atoms next to the graphitic-N species in NG-1000 serves as the main active species for CO 2 RR. In addition, such a non-metal based electrocatalyst is capable of achieving an excellent selectivity of 95.0 % at −0.72 V versus RHE to convert CO 2 into CO, with a CO current density of 9.07 mA cm−2, comparable to the state-of-the-art metal-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Two new metal aluminium phosphate millimetre-crystals NaBa 2 Al(P 2 O 7) 2 and NaBaAl(PO 4) 2 were successfully grown by using high-temperature molten method. The crystals NaBa 2 Al(P 2 O 7) 2 and NaBaAl(PO 4) 2 are located in space groups P ¯1 and P 2 1 /c, respectively. NaBa 2 Al(P 2 O 7) 2 displays a [Al(P 2 O 7) 2 ] 1D chain structure constructed from corner-sharing linkage of novel AlP 4 O 16 9− anion groups, and the AlP 4 O 16 9− group is formed by edge-sharing connection of two P 2 O 7 dimers and one AlO 6 octahedron. However, NaBaAl(PO 4) 2 exhibits a new [Al(PO 4) 2 ] 2D layer structure composed of AlP 2 O 10 7− anion groups via corner-sharing, and the AlP 2 O 10 7− group is generated by alternate linkages of corner-sharing PO 4 and AlO 4 tetrahedra. Analysis based on Pauling's electrostatic rule and Brown's bond valence model finds that structural feature of the two anion groups is mainly responsible for their different dimension structures in addition to structure-directed role of large Ba2+. The two crystals manifest a deep-UV optical transparency below 190 ​nm and good thermal stability, making them a potential optical window material. First-principles calculations reveal that the optical bandgaps of both crystals are determined by the Ba–O groups, rather than Al–O and P–O common groups. Structural feature of anion groups is responsible for different dimension frameworks for two new deep-UV optical aluminium phosphate crystals NaBa 2 Al(P 2 O 7) 2 containing [Al(P 2 O 7) 2 ] 1D chain and NaBaAl(PO 4) 2 featuring [Al(PO 4) 2 ] 2D layer. [Display omitted] • NaBa 2 Al(P 2 O 7) 2 contains novel AlP 4 O 16 9− group. • Structure unit conformations and Ba2+ induce different frameworks. • Millimetre-crystals are grown by using high-temperature molten method. • Optical properties are determined by BaO n polyhedra. [ABSTRACT FROM AUTHOR]