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Cable-in-conduit conductor (CICC), one of the most promising conductors for manufacturing magnets in magnetic confinement fusion devices, has attracted lots of attention. In the production of CICC, porosity control is necessary for its stability. The porosity control is usually realized by the diameter-reducing process, which would also lead to indentation damages to the elements of CICC-superconducting wires. In this article, systematic research of indentation damages was carried out on the next generation of high-temperature superconducting materials–Bi-2212 wires. The results indicate that the current carrying capacity of the indentation-damaged wire would first keep steady and then show exponential decline with the increase of indentation depth. The wires subjected to pre-overpressure (pre-OP) treatment exhibit slightly improved resistance against indentation damage at shallow indentation depths. However, their critical current (I c) deteriorates more rapidly at greater indentation depths when compared to wires that have not undergone the per-OP process. The following structural characterization analyzed the reasons for the property changes with the help of scanning electron microscopy, energy dispersive x-ray spectroscopy, computed tomography, and hardness tester. Misalignment between the Bi-2212 grains and shaped filaments was found in the indentation-damaged wires, with which the degradation in I c of the wires and the differences in properties of the two kinds of wires were further discussed. [ABSTRACT FROM AUTHOR]

A Ce atom reaction with propene is carried out in a pulsed laser vaporization molecule beam source. Several Ce–hydrocarbon species formed by the C—H and C—C bond activation of propene are observed by time-of-flight mass spectrometry, and Ce(C3Hn) (n = 4 and 6) are characterized by mass-analyzed threshold ionization (MATI) spectroscopy and density functional theory, multiconfiguration, and relativistic quantum chemical calculations. The MATI spectrum of each species consists of two vibronic band systems, each with several vibronic bands. Ce(C3H6) is identified as an inserted species with Ce inserting into an allylic C—H bond of propene and Ce(C3H4) as a metallocycle through 1,2-vinylic dehydrogenation. Both species have a Cs structure with the Ce 4f16s1 ground valence electron configuration in the neutral molecule and the Ce 4f1 configuration in the singly charged ion. The two vibronic band systems observed for each species are attributed to the ionization of two pairs of the lowest spin–orbit coupled states with each pair being nearly degenerate. [ABSTRACT FROM AUTHOR]

The particular and homogeneous solutions of two-dimension (2D) thermal-elastic problems are expressed by using the virtual boundary element method (VBEM) and the superposition principle. Accordingly, two matrix equations are needed and formed for particular and homogeneous solutions by the novel nonsingular boundary element method with the radial basis function interpolation (RBFI), namely virtual boundary meshfree Galerkin method (VBMGM). Considering the boundary conditions of heat conduction and combining the Galerkin method, virtual source functions of particular solutions can be solved by first using VBMGM. Applying boundary conditions of transformation, virtual source functions of homogeneous solutions can be obtained by second employing VBMGM. The coefficients of two matrix equations are symmetrical. Formed equations are nonsingular and have merits of virtual boundary element method, meshfree method, and Galerkin method. The detailed expressions, calculation steps, and simplified flow chart are given in detail, that is convenient for other scholars to study other more complex thermo-elastic problems through the method of this paper. Three examples are calculated. Comparing their calculation results with other methods, the stability and the precision of VBMGM for 2D thermal-elastic problems are validated. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The conversion of CF3‐alkenes to gem‐difluoroalkenes using reductive cross‐coupling strategy has received much attention in recent years, however, the use of green and readily available reducing salt to mediate these reactions remains to be explored. In this work, a concise construction of gem‐difluoroalkenes, which requires neither a catalyst nor a metal reducing agent, was established. Rongalite, a safe and inexpensive industrial product, was employed as both a radical initiator and reductant. This procedure was compatible with both linear and cyclic diaryliodonium salts, enabling a wide variety of substrates (>70 examples). The utility of this approach was demonstrated through gram‐scale synthesis and efficient late‐stage functionalizations of anti‐inflammatory drugs. [ABSTRACT FROM AUTHOR]

Solutions of 3D thermal analysis in inhomogeneous media with variable thermal source are divided into homogeneous and particular solutions by a novel boundary-type element-free method, namely virtual boundary element-free Galerkin method (VBEFGM). The homogeneous solution can be obtained by the virtual boundary element-free method (VBEFM). The virtual source function of the homogeneous solution and the unknown coefficient of the particular solution are constructed by the radial basis function interpolation (RBFI). And VBEFGM for 3D thermal analysis in inhomogeneous media with variable thermal source is real meshfree and does not require the background integral element. Its equation is obtained the Galerkin method of the weighted residual methods. The demonstration of ANSYS Parametric Design Language (APDL) can greatly facilitate the programming for the extraction of the coordinate information and the outer normal cosines on nodes. The calculation scheme and the specific weighted coefficients are deducted in detail for 3D thermal analysis in inhomogeneous media with variable thermal source by VBEFGM. The numerical calculational steps and flow chart are given. Three numerical examples are computed. The results are compared with other numerical methods and the exact solutions. The stability and the accuracy of the proposed method is proved by VBEFGM for 3D thermal analysis in inhomogeneous media with variable thermal source. [ABSTRACT FROM AUTHOR]

A new boundary-type meshfree collection method, namely the virtual boundary element-free Galerkin method (VBEFGM), is demonstrated for three-dimension (3-D) multi-domain steady-state heat conduction problems. The virtual source functions of the virtual nodes are constructed by the radial basis function interpolation. And the virtual and real boundaries are discreted into the virtual and real nodes. 3-D multi-domain steady-state heat conduction problems are solved without the background integral element by VBEFGM. Using the Galerkin method to obtain the formula of VBEFGM, the proposed method has the advantages of the virtual boundary element-free method, the meshfree collection method and the Galerkin method. It is easily programed and extended to solve other more complicated 3-D heat conduction problems, since the detailed calculation scheme is deduced and shown. Two numerical examples of the boundary conditions varying with the space are computed. The computational results are compared with other numerical methods. The accuracy and stability of the proposed method are validated for 3-D multi-domain steady-state heat conduction problems. [ABSTRACT FROM AUTHOR]

The virtual boundary meshfree Galerkin method (VBMGM) is further developed to compute three-dimensional single-domain steady-state heat conduction problem. Using VBMGM, three-dimensional problem is reduced into two-dimensional boundary, whose element information can be obtained by the meshing software, namely ANSYS software. It greatly facilitates the programing implementation of the proposed method that ANSYS Parametric Design Language (APDL) is demonstrated for the element information acquisition of the curved surface. The virtual source function on the virtual boundary element method (VBEM) is interpolated by the radial basis function interpolation (RBFI) of the meshfree method. The calculation equation of three-dimensional single-domain steady-state heat conduction problem by VBMGM is constructed by the Galerkin method of the weighted residual method. Therefore, it has the advantages of the VBEM, the meshfree method and the Galerkin method that the proposed method is employed to computed three-dimensional single-domain steady-state heat conduction problem. It is beneficial to further popularize the proposed method to solve other three-dimensional heat conduction problems that the detailed numerical discrete formula of the proposed method for three-dimensional single-domain steady-state heat conduction problem is obtained. The numerical results of two numerical examples are computed and compared with the other numerical method and the extract solutions. The accuracy and stability of VBMGM for three-dimensional single-domain steady-state heat conduction problem are verified. [ABSTRACT FROM AUTHOR]

Metal-pyridine (metal=Li, Ca, and Sc) complexes are produced inlaser-vaporization molecular beams and studied by pulsed-field-ionization zero-electron-kinetic-energy (ZEKE) spectroscopy and theoretical calculations. Both σ and π structures are considered for the three complexes by theory, and preferred structures are determined by the combination of the ZEKE spectra and calculations. The Li and Ca complexes prefer a σ bonding mode, whereas the Sc complex favors a π mode. Adiabatic ionization energies and metal-ligand vibrational frequencies are determined from the ZEKE spectra. Metal-ligand bond dissociation energies of the neutral complexes are obtained from a thermodynamic cycle. The ionization energies follow the trend of Li-pyridine (32 460 cm-1)≤Ca-pyridine(39 043 cm-1)≤Sc-pyridine(42 816 cm-1), whereas the bond energies are in the order of Ca-pyridine (27.0 kJ mol-1)≤Li-pyridine(49.1 kJ mol-1)≤Sc-pyridine(110.6 kJ mol-1). The different bonding modes between the main group metals and transition element are discussed in terms of Sc 3d orbital involvement. The bond energy differences between the Li and Ca metals are explained by the number of valence s electrons and the size of the metal atoms. [ABSTRACT FROM AUTHOR]

Graphene quantum dots (GQDs) have been synthesized reproducibly by chemical oxidation (CO) of carbon nano-onions (nCNOs) and a one-step pulsed laser ablation (LA) of nCNOs in deionized water. The photoluminescence (PL) spectra show that the LA-GQDs have blue shifted emission relative to the CO-GQDs which is attributed to the effects of both particle sizes and surface functional groups. The CO-GQDs have an average diameter of 4.1(8) nm and a thickness corresponding to two or three graphene layers, while the LA-GQDs have an average diameter of 1.8(6) nm and a thickness comparable to a single layer of graphene. The CO-GQDs favor the presence of carboxylic groups and have a higher fraction of sp 2 carbons, while the LA-GQDs prefer the presence of hydroxyl groups and have a higher fraction of sp 3 carbons. PL lifetime data suggests that surface functional groups are the main source of radiative deactivation and the sp 2 carbon domains are mainly responsible for non-radiative decay. PL lifetimes are measured to be 7.9(6) ns for the emission from the carboxylic groups and 3.18(10) ns from the hydroxyl groups. Compared to CO, liquid-phase LA is a faster and cleaner one-step method for producing GQDs with fewer starting chemicals and byproducts. [ABSTRACT FROM AUTHOR]

Vibrational frequencies of three niobium normal modes of triniobium dicarbide neutral and cation have been determined from pulsed field ionization-zero electron kinetic energy photoelectron spectra. The niobium stretching mode has a frequency of 326 cm[SUP-1]in the neutral and 339 cm[SUP-1]in the ion. The two deformation modes have frequencies of 238 and 82 cm[SUP-1]in the neutral and a degenerate frequency of 258 cm[SUP-1]in the ion. The geometry of the triniobium dicarbide has been established by comparing the experimental spectra with theoretical calculations. The cluster has a trigonal bipyramid geometry with carbon atoms capping on each face of the metal frame. The cation cluster has D[SUB3h] symmetry whereas the neutral cluster has lower symmetry resulting from a Jahn-Teller distortion. A second low-lying structure with doubly bridging carbon atoms has been identified by the calculations but has not yet been observed. [ABSTRACT FROM AUTHOR]

The geometrical structures of the ground states of triniobium monoxide, Nb3O, and its cation, Nb3O+, have been determined by an experimental and theoretical study. Vibrationally resolved photoelectron spectra of an Nb3O cluster beam were obtained at 100 and 300 K using the pulsed field ionization-zero electron kinetic energy technique. The spectra were simulated by calculating multidimensional Franck–Condon factors using the geometries and harmonic vibrational frequencies obtained from density functional theory for the minimum energy structures of the ion and neutral molecule. The rather remarkable agreement between the experiment and the simulated spectra establishes that Nb3O and Nb3O+ have planar C2v structures with the oxygen atom bridging two niobium atoms. These are the most complex transition metal cluster structures to date to be characterized by gas phase spectroscopic techniques. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The technique of pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE), photoelectron spectroscopy was employed to probe the electronic structure of the V+2 cation. Rotationally resolved PFI-ZEKE spectra of the V+2 ground state were obtained by two color excitation via the 700 nm A 3Πu←X 3Σ-g system. The observation of transitions from the A 3Π2u state to two spin–orbit components with Ω=1/2 and Ω=3/2, confirms that the cation ground state has 4Σg- symmetry, in accordance with previous experimental and theoretical work. Striking differences were observed in the rotational selection rules for the 4Σg-←A 3Π1u and the 4Σg-←A 3Π2u transitions. The adiabatic ionization potential of V2 was determined to be 51 271.14(50) cm-1. From an analysis of the rotational structure of the PFI-ZEKE spectra, the following molecular constants were determined for the 4Σg- state: r0=1.7347(24) Å, second order spin–orbit splitting, λ=5.248(17) cm-1, spin–rotation constant, γ=0.0097(87) cm-1, T0=51 282.20(50) cm-1 (1σ error bounds). © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The virtual boundary meshfree Galerkin method (VBMGM) is given to calculate the multi-domain transient heat conduction with heat source problem. The radial basis function interpolation is used to obtain the virtual source function on the virtual boundary, the heat source, the particular solutions of the temperature, and the heat flux in the computational domain. The formula of the proposed method is gotten by the Galerkin method and the control equations of the multi-domain transient heat conduction with heat source. Therefore, there are the advantages of the Galerkin method, the boundary element method, and the meshfree method for the multi-domain transient heat conduction with heat source problem by VBMGM. The numerical meaning of the weighted values are definite for the multi-domain transient heat conduction with heat source problem through VBMGM, such as the partial derivatives of the temperature, the heat flux, the heat source, and the continuity conditions on the public boundary at time. The detailed calculation scheme of VBMGM is deducted for the multi-domain transient heat conduction with heat source problem. Two numerical examples, four subdomains with the time-dependent heat source problem and two subdomains with the constant heat source and mixed boundary condition problem, are computed. The accuracy and the stability of VBMGM for the multi-domain transient heat conduction with heat source problem are verified. [ABSTRACT FROM AUTHOR]

The virtual boundary meshfree Galerkin method (VBMGM) is demonstrated to solve the single-domain transient heat conduction with heat source problem. Both the heat source in the computational domain and the virtual source function on the virtual boundary are interpolated by using the radial basis function interpolation. The equation of the proposed method is formed by the Galerkin method. Consequently, VBMGM have the advantages of the Galerkin method, the boundary element method and the meshfree method for the single-domain transient heat conduction with heat source problem. And the numerical definitions of the weighted values in VBMGM are definite, such as the partial derivatives of the temperature, the heat flux and the heat source expression at t + Δ t time. The detailed equation of VBMGM is deducted for the single-domain transient heat conduction with heat source problem. Two numerical examples, the square domain with constant heat source and the square domain with variable boundary condition and variable heat source, are presented. The accuracy and the stability of VBMGM for the single-domain transient heat conduction with heat source problem are proved. [ABSTRACT FROM AUTHOR]

Metal-mediated N–H and C–H bond activation of aliphatic amines is an effective strategy for synthesizing biologically important molecules. Ln (Ln = La and Ce) atom reactions with dimethylamine are carried out in a pulsed-laser vaporization supersonic molecular beam source. A series of dehydrogenation species are observed with time-of-flight mass spectrometry, and the dehydrogenated Ln-containing species in the formula Ln(CH2NCH3) are characterized by single-photon mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical calculations. The theoretical calculations include density functional theory for both Ln species and multiconfiguration self-consistent field and quasi-degenerate perturbation theory for the Ce species. The MATI spectrum of La(CH2NCH3) consists of a single vibronic band system, which is assigned to the ionization of the doublet ground state of N-methyl-lanthanaaziridine. The MATI spectrum of Ce(CH2NCH3) displays two vibronic band systems, which are attributed to the ionization of two-pair lowest-energy spin–orbit coupling states of N-methyl-ceraaziridine. Both metallaaziridines are three-membered metallacycles and formed by the thermodynamically and kinetically favorable concerted dehydrogenation of the amino group and one of the methyl groups. [ABSTRACT FROM AUTHOR]

Although it plays a critical role in the photophysics and catalysis of lanthanides, spin–orbit coupling of electrons on individual lanthanide atoms in small clusters is not well understood. The major objective of this work is to probe such coupling of the praseodymium (Pr) 4f and 6s electrons in Pr2O2 and Pr2O2+. The approach combines mass-analyzed threshold ionization spectroscopy and spin–orbit multiconfiguration second-order quasi-degenerate perturbation theory. The energies of six ionization transitions are precisely measured; the adiabatic ionization energy of the neutral cluster is 38 045 (5) cm−1. Most of the electronic states involved in these transitions are identified as spin–orbit coupled states consisting of two or more electron spins. The electron configurations of these states are 4f46s2 for the neutral cluster and 4f46s for the singly charged cation, both in planar rhombus-type structures. The spin–orbit splitting due to the coupling of the electrons on the separate Pr atoms is on the order of hundreds of wavenumbers. [ABSTRACT FROM AUTHOR]

A new high-precision boundary meshfree method, namely virtual boundary meshfree Galerkin method (VBMGM), for calculating the multi-domain constant coefficient heat conduction with a heat source problem is given. In the paper, the radial basis function interpolation is used to solve the virtual source function of virtual boundary and the heat source within each subdomain. Simultaneously, the equation of VBMGM for multi-domain constant coefficient heat conduction with a heat source problem is obtained by the Galerkin method. Therefore, the proposed method has common advantages of the boundary element method, meshfree method, and Galerkin method. Coefficient matrix of this specific expression is symmetrical and the specific expression of VBMGM for the multi-domain constant coefficient heat conduction with a heat source problem is given. Two numerical examples are given. The numerical results are also compared with other numerical methods. The accuracy and feasibility of the method for the multi-domain constant coefficient heat conduction with a heat source problem are proved. [ABSTRACT FROM PUBLISHER]

Virtual boundary meshfree Galerkin method (VBMGM) is developed to solve the multi-domain variable coefficient heat conduction problem with heat source. Both the virtual source function on the virtual boundary and heat source within each subdomain are approximate by the radial basis function interpolation. The equation of the proposed technique is derived by one of the weighted residual methods, namely the Galerkin method, for multi-domain variable coefficient heat conduction problem with heat source. Therefore, VBMGM simultaneously possesses the merits of Galerkin method, boundary element method and meshfree method. And the numerical meanings of the weighted values are definite, such as the partial derivative heat source expressions, the temperature, the heat flux and the continuity conditions, in VBMGM for multi-domain variable coefficient heat conduction problem with heat source. The specific and detailed equation of VBMGM is obtained for multi-domain variable coefficient heat conduction problem with heat source. The accuracy and the stability of the proposed technique are validated by two numerical examples for multi-domain variable coefficient heat conduction problem with heat source. [ABSTRACT FROM AUTHOR]

Ln (Ln = La and Ce) atom reactions with methylamine are carried out in a pulsed-laser vaporization supersonic molecular beam source. A series of dehydrogenation species are observed with time-of-flight mass spectrometry, and the dehydrogenated Ln-containing species in the formula Ln(NCH3) are characterized by mass-analyzed threshold ionization (MATI) spectroscopy and density functional theory and multiconfiguration spin–orbit coupling computations. The MATI spectrum of La(NCH3) consists of two vibronic band systems that are assigned to the ionization of the 2A1 ground state of the C3v isomer La(N–CH3) and the 2A′ ground state of the Cs isomer La(NH–CH2). The MATI spectrum of Ce(NCH3) also displays two band systems, which are attributed to the ionization of the low-energy spin–orbit coupling states of the C3v isomer Ce(N–CH3). Ln(N–CH3) is formed by the concerted dehydrogenation of the amino group, while La(NH–CH2) is formed by the dehydrogenation of both amino and methyl groups. Ce(NH–CH2) is presumably formed in the reaction based on the computational predictions but not observed by the spectroscopic measurements. [ABSTRACT FROM AUTHOR]

In this article, a new high-precision boundary-type mesh-free method, called the virtual boundary mesh-free Galerkin method (VBMGM), is given for analyzing the heat conduction problem consisting of multiple media. A control equation of the proposed method is established by the the Galerkin method of the weighted residual methods. The virtual source function is approached through the radial basis function interpolation in the mesh-free method. Thus, the main feature of the proposed technique has the advantages of the mesh-free method, the boundary-element method, and the Galerkin method, a symmetrical coefficient matrix. The numerical meanings of the weighted values in the VBMGM equation, such as the partial derivatives the temperature, the heat flux, the temperature connection condition, and the heat flux connection condition, are clear. Numerical examples of a thick-walled cylinder consisting of two media and a two-layered rectangular plate are provided. The feasibility and the accuracy of the proposed technique are proved. [ABSTRACT FROM AUTHOR]

The virtual boundary meshfree Galerkin method (VBMGM) is presented to calculate the single-domain heat conduction with heat source problem. The virtual source function of the virtual boundary and the heat source in the computational domain both are interpolated by the radial basis function interpolation. The equation of the proposed method is obtained by the Galerkin method of the weighted residual methods. Consequently, VBMGM possesses the advantages of Galerkin method, boundary element method and meshfree method. And the numerical meanings of the weighted values in VBMGM, such as the partial derivative the temperature, the heat flux and the heat source expression, are definite. The detailed and specific equation of VBMGM is deducted. The numerical examples, namely the temperatures of the rectangular domain and the square domain, are computed. And the accuracy and the stability of the proposed method for the single-domain heat conduction with heat source problem are validated. [ABSTRACT FROM AUTHOR]

The development of the powder metallurgy (PM) superalloy applied in turbine discs of high thrust-weight ratio aeroengines was reviewed. Based on the Cosserat continuum theory, the elastoplastic damage model for the PM superalloy was developed in which the microscopic properties were modeled with the characteristic lengths of the material. Furthermore, the mesh dependency of the localized bands in the analysis of softening problems was eliminated in the present model. For the softening problems, massive iterations were usually needed with the classical elastoplastic methods and may not converge in some cases. Based on the parametric variational principle, the original nonlinear problem was transferred to a complementary problem, then the efficiency and convergence of the solution were greatly improved. Finally, several numerical examples demonstrate the validity of the proposed method. [ABSTRACT FROM AUTHOR]

This article presents a virtual boundary meshless with Trefftz method for calculation of the two-dimensional steady-state heat conduction crack problem, which is based on the idea of multidomain combination. The virtual source function is constructed by the radial basis functions approximation in the subdomain not containing the crack. The temperature or heat flux is calculated by crack special solution of Trefftz function in the crack subdomain. Thus, the proposed method has the advantages of both the boundary-type meshless method and the Trefftz method. No nodes or elements are distributed on the crack, because the boundary condition of the crack is automatically satisfied by employing the crack special solution of the Trefftz function. The heat stress intensity factor is simply and directly calculated. [ABSTRACT FROM PUBLISHER]

Ce atom reactions with ethylene, 2-butene, and isobutene are carried out in a pulsed laser vaporization molecule beam source. Ce-containing species are observed with time-of-flight mass spectrometry, and Ce(C4H6) is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and relativistic quantum chemical calculations. Two structural isomers are identified for Ce(C4H6): one is the tetrahedronlike Ce[C(CH2)3] in C3v symmetry and the other is the five-membered metallocyclic Ce(CH2CHCHCH2) in Cs. The MATI spectrum of the C3v isomer exhibits two vibronic band systems separated by 88 cm−1, while that of the Cs isomer displays three split by 60 and 101 cm−1. The multiple band systems are attributed to spin-orbit splitting and vibronic transitions involving metal-hydrocarbon and hydrocarbon-based vibrations. The splitting in the C3v isomer arises from interactions of two triplet and two singlet states at the lowest energies, while each splitting in the Cs isomer involves two triplets and a singlet. Although the Ce atom has ground electron configuration 4f15d16s2, Ce valence electron configurations in both isomers are 4f16s1 in the neutral ground state and 4f1 in the ion. The remaining Ce 5d electrons in the isolated atom are spin paired in molecular orbitals that are a bonding combination between Ce 5dπ and hydrocarbon π* orbitals. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the design of observer for discrete-time Takagi–Sugeno fuzzy systems. Under the framework of multi-instant matrix, a novel fuzzy observer and a new Lyapunov function, which are parameter-dependent on m-steps normalized fuzzy weighting functions, are proposed for conceiving less conservative observer design conditions. In particular, some existing fuzzy Lyapunov functions and fuzzy observers are special cases of the new Lyapunov function and fuzzy observer, respectively. Furthermore, the obtained fuzzy observer design conditions are further relaxed by fully considering the algebraic properties of m-steps normalized fuzzy weighting functions. Finally, a numerical example is given to illustrate the effectiveness of the proposed results. [Copyright &y& Elsevier]

Group 6 metal–bis(mesitylene)sandwich complexes are produced by interactions between the laser-vaporizedmetal atoms and mesitylene vapor in a pulsed molecular beam source,identified by photoionization time-of-flight mass spectrometry, andstudied by pulsed-field ionization zero-electron kinetic energy spectroscopyand density functional theory calculations. Although transition metal–bis(arene)sandwich complexes may adopt eclipsed and staggered conformations,the group 6 metal–bis(mesitylene) complexes are determinedto be in the eclipsed form. In this form, rotational conformers withmethyl group dihedral angles of 0 and 60° are identified forthe Cr complex, whereas the 0° rotamer is observed for the Moand W species. The 0° rotamer is in a C2vsymmetry with the neutral ground stateof 1A1and the singly positive charged ion stateof 2A1. The 60° rotamer is in a Cisymmetry with the neutralground state of 1Agand the ion state of 2Ag. Partial conversion of the 60 to 0° rotameris observed from He to He/Ar supersonic expansion for Cr–bis(mesitylene).The unsuccessful observation of the 60° rotamer for the Mo andW complexes is the result of its complete conversion to the 0°rotamer in both He and He/Ar expansions. The adiabatic ionizationenergies of the 0° rotamers of the three complexes are in theorder of Cr–bis(mesitylene) < W–bis(mesitylene)

Ln (Ln = La and Ce) atom reactions with ammonia are carried out in a pulsed laser vaporization supersonic molecular beam source. Lanthanide-containing species are observed with time-of-flight mass spectrometry, and LnNH molecules are characterized by mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical calculations. The theoretical calculations include density functional theory for both Ln species and a scalar relativity correction, electron correlation, and spin-orbit coupling for the Ce species. The MATI spectrum of LaNH exhibits a single vibronic band system with a strong origin band and two weak vibronic progressions, whereas the spectrum of CeNH displays two band systems separated by 75 cm−1 with each being like the LaNH spectrum. By comparing with the theoretical calculations, both LaNH and CeNH are identified as linear molecules with C∞v symmetry, and the two vibronic progressions are attributed to the excitations of Ln–N stretching and Ln–N–H bending modes in the ions. The additional band system observed for CeNH is due to the spin-orbit splitting from the interactions of triplet and singlet states. The ground valence electron configurations of LaNH and CeNH are La 6s1 and Ce 4f16s1, and the ionization of each species removes the Ln 6s1 electron. The remaining two electrons that are associated with the isolated Ln atoms or ions are in a doubly degenerate molecular orbital that is a bonding combination between Ln 5dπ and N pπ orbitals. [ABSTRACT FROM AUTHOR]

The networked synchronization problem of a class of master-slave chaotic systems with time-varying communication topologies is investigated in this paper. Based on algebraic graph theory and matrix theory, a simple linear state feedback controller is designed to synchronize the master chaotic system and the slave chaotic systems with a timevarying communication topology connection. The exponential stability of the closed-loop networked synchronization error system is guaranteed by applying Lyapunov stability theory. The derived novel criteria are in the form of linear matrix inequalities (LMIs), which are easy to examine and tremendously reduce the computation burden from the feedback matrices. This paper provides an alternative networked secure communication scheme which can be extended conveniently. An illustrative example is given to demonstrate the effectiveness of the proposed networked synchronization method. [ABSTRACT FROM AUTHOR]

The vibrational structure of the Ag+NH3 complex has been investigated by single-photon zero kinetic energy (ZEKE) photoelectron spectroscopy. The intermolecular stretching mode with a frequency of 375 cm−1 is measured from the ZEKE spectrum, whereas the intermolecular bending vibration is not observed, in contrast to the A˜2E1/2–X˜2A1 electronic spectrum of the neutral AgNH3 complex [Miyawaki et al., Chem. Phys. Lett. 302 (1999) 354]. The ionization potential of AgNH3 was determined to be 47580 cm−1 (5.899 eV). [Copyright &y& Elsevier]

La atom reaction with isoprene is carried out in a laser-vaporization molecular beam source. The reaction yields an adduct as the major product and C—C cleaved and dehydrogenated species as the minor ones. La(C5H8), La(C2H2), and La(C3H4) are characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of all three species exhibit a strong origin band and several weak vibronic bands corresponding to La-ligand stretch and ligand-based bend excitations. La(C5H8) is a five-membered metallacycle, whereas La(C2H2) and La(C3H4) are three-membered rings. All three metallacycles prefer a doublet ground state with a La 6s1-based valence electron configuration and a singlet ion. The five-membered metallacycle is formed through La addition and isoprene isomerization, whereas the two three-membered rings are produced by La addition and insertion, hydrogen migration, and carbon-carbon bond cleavage. [ABSTRACT FROM AUTHOR]

The precise ionization energy of praseodymium oxide (PrO) seeded in supersonic molecular beams is measured with mass-analyzed threshold ionization (MATI) spectroscopy. A total of 33 spin–orbit (SO) states of PrO and 23 SO states of PrO+ are predicted by second-order multiconfigurational quasi-degenerate perturbation (MCQDPT2) theory. Electronic transitions from four low-energy SO levels of the neutral molecule to the ground state of the singly charged cation are identified by combining the MATI spectroscopic measurements with the MCQDPT2 calculations. The precise ionization energy is used to reassess the ionization energies and the reaction enthalpies of the Pr + O → PrO+ + e− chemi-ionization reaction reported in the literature. An empirical formula that uses atomic electronic parameters is proposed to predict the ionization energies of lanthanide monoxides, and the empirical calculations match well with available precise experimental measurements. [ABSTRACT FROM AUTHOR]

Vibronic spectra of lutetium oxide (LuO) seeded in supersonic molecule beams are investigated with mass-analyzed threshold ionization (MATI) spectroscopy and second-order multiconfigurational quasi-degenerate perturbation (MCQDPT2) theory. Six states of LuO and four states of LuO+ are located by the MCQDPT2 calculations, and an a3Π(LuO+) ← C2Σ+ (LuΟ) transition is observed by the MATI measurement. The vibronic spectra show abnormal vibrational intervals for both the neural and cation excited states, and the abnormality is attributed to vibrational perturbations induced by interactions with neighboring states. [ABSTRACT FROM AUTHOR]

In the trend of multi‐energy integration development and the intellectualisation for demand‐side, the application of integrated energy system (IES) contained demand response is of great significance to the economic operation of energy systems. The energy hubs are widely studied as effective tools for integrating regional energy in the IES. With the expansion of schedulable devices, the mode of multiple energy hubs (MEHs) cooperative operation is proposed in this study. Moreover, in order to adjust the periodic loads, the authors further study the responsiveness of electric vehicles, air‐conditioning and energy storages according to time‐of‐use price incentive mechanisms, and the total operation cost is minimised. Meanwhile, the eco‐friendly target is achieved by the pollutant trading market. Furthermore, due to the complementary characteristic of MEHs, the economics allocation issues are also carefully considered where the cost and benefit of each participant are allocated by cooperative game theory to make them satisfied with the profit brought by cooperation. The simulation takes three hubs cooperation as an example to verify the effectiveness of the proposed methods. The results show that the total profit increased by 53.54% and the peak load is reduced by 27.06% after optimal operation, and the modified propensity to disrupt verifies the fairness of allocation. [ABSTRACT FROM AUTHOR]

Jarosites are secondary iron-hydroxyl-sulfate minerals and widely occur in bioleaching, acid mine drainage, and acid sulfate soil environments. Anaerobic reductive dissolution of jarosites is yet to be methodically examined. In this study, we explored the bio-dissolution of jarosites by Acidithiobacillus ferrooxidans (At. ferrooxidans) by using hydrogen in batch experiments. After bio-dissolution by At. ferrooxidans for 22 d, ferrous ion concentrations reached 10.07 mM (biologically produced jarosites), 7.68 mM (potassium jarosite), and 1.45 mM (lead jarosite). Strengthening the dissolved jarosites by decreasing the initial pH (pH < 2.0) or by adding citric acid (1, 5, and 10 mM) was inefficient for bio-dissolution owing to restricted cellular activity. The pathways of bio-dissolution should include direct contact bio-dissolution and indirect bio-dissolution and relate to the solubility of jarosites in a bio-dissolution system. The results demonstrate that anaerobic reductive bio-dissolution of jarosites by At. ferrooxidans using hydrogen shows potential. This study also provides opportunities to contribute to the development of the bioleaching field via the aerobic/anaerobic cycle using a single strain to control and reuse jarosites in situ. Unlabelled Image • Reductive dissolution of jarosites is achieved anaerobically by At. ferrooxidans using H 2. • Acid consumption of jarosites bio-dissolution using H 2 can be reduced significantly. • Jarosites bio-dissolution cannot be enhanced by decreasing pH or adding citric acid. • Bio-dissolution of jarosites is via direct and indirect pathways. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons are model systems for studying the mechanisms of lithium storage in carbonaceous materials. In this work, Li complexes of naphthalene, pyrene, perylene, and coronene were synthesized in a supersonic metal-cluster beam source and studied by zero-electron-kinetic-energy (ZEKE) electron spectroscopy and density functional theory calculations. The adiabatic ionization energies of the neutral complexes and frequencies of up to nine vibrational modes in the singly charged cations were determined from the ZEKE spectra. The metal-ligand bond energies of the neutral complexes were obtained from a thermodynamic cycle. Preferred Li/Li+ binding sites with the aromatic molecules were determined by comparing the measured spectra with theoretical calculations. Li and Li+ prefer the ring-over binding to the benzene ring with a higher π-electron content and aromaticity. Although the ionization energies of the Li complexes show no clear correlation with the size of the aromatic molecules, the metal-ligand bond energies increase with the extension of the π-electron network up to perylene, then decrease from perylene to coronene. The trends in the ionization and metal-ligand bond dissociation energies of the complexes are discussed in terms of the orbital energies, local quadrupole moments, and polarizabilities of the free ligands and the charge transfer between the metal atom and aromatic molecules. [ABSTRACT FROM AUTHOR]

Copper-diammonia, Cu(NH3)2, and its deuterated species, Cu(ND3)2, are produced in supersonic molecular beams and studied by pulsed-field ionization zero electron kinetic energy photoelectron spectroscopy and ab initio calculations. Structural isomers with a copper atom binding to an ammonia dimer or two ammonia molecules are obtained by the calculations. By comparing the experimental measurements to the theoretical calculations, the neutral and ionic forms of copper-diammonia are determined to be in a doubly bound linear conformation in their ground electronic states. The adiabatic ionization potentials of Cu(NH3)2 and Cu(ND3)2 are measured as 29 532 (5) and 29 313 (5) cm-1, respectively. The metal-ligand symmetric stretching frequencies are measured to be 436 cm-1 for Cu+–(NH3)2 and 398 cm-1 for Cu+–(ND3)2, and the metal-ligand bending frequencies 75/139 cm-1 for Cu/Cu+–(NH3)2 and 70/125 cm-1 for Cu/Cu+–(ND3)2. Moreover, the dissociation energy of Cu(NH3)2→CuNH3+NH3 is determined to be 11(3) kcal mol-1 through a thermodynamic relationship. [ABSTRACT FROM AUTHOR]

The yttrium complexes with one and two dimethyl ethers and their deuterated derivatives are prepared with laser vaporization molecular beam techniques, identified with photoionization time-of-flight mass spectrometry, and investigated with pulsed-field-ionization zero-electronkinetic-energy (ZEKE) photoelectron spectroscopy and ab initio calculations. Adiabatic ionization potentials and yttrium-oxygen stretch and ether-based vibrations are measured for the 1:1 and 1:2 complexes. Fermi interactions are observed from the ZEKE spectra of the 1:1 species. The ground electronic states of the monoligand complexes are determined to be [SUP2]A[SUB2] for the neutral and [SUP1]A[SUB1] for the singly charged positive ion, both in C[SUB2v] symmetry, with yttrium binding to oxygen. The coordination of a second ether forms a diligand complex with a linear oxygen-yttrium-oxygen configuration. This is the first electronic-vibrational spectroscopic study of yttrium-polyatomic molecule complexes and weakly bound metal complexes with two or more polyatomic molecules. [ABSTRACT FROM AUTHOR]

Aluminum-trimethylphosphine and trimethylarsine have been prepared by pulsed laser vaporization. Their electronic spectra have been obtained for the first time, using pulsed field ionization zero electron kinetic energy (ZEKE) photoelectron spectroscopy. The ZEKE spectra reveal the information about adiabatic ionization energies, intermolecular and ligand vibrations, and charge effects on molecular geometries. In coordination with the experimental measurements, density functional theory has been used to calculate equilibrium geometries, vibrational frequencies, and bond dissociation energies for the neutral and ionic complexes. The calculations predict that ionization causes the most significant geometry changes in the Al–P–C or Al–As–C angles, in agreement with the experimental observations. The aluminum ion and atom bind phosphorus more strongly than arsenic in these species. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract La atom reactions with 1,4-pentadiene and 1-pentyne are carried out in a laser-vaporization molecular beam source. Both reactions yield a predominant La(C 5 H 6) radical from ligand dehydrogenation and a minor La(C 3 H 4) species from C C bond cleavage. The metal-hydrocarbon radicals are characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of each species formed by the two reactions are essentially identical and consist of a single vibronic band system for La(C 5 H 6) and two band systems for La(C 3 H 4). Each band system exhibits a strong origin band and several weak vibronic ones. Adiabatic ionization energies, metal-ligand vibrational frequencies, and low-frequency ligand-based modes are measured for the two species. La(C 5 H 6) is identified as a six-membered lanthanacycle [La(CHCHCHCHCH 2)] (Iso A, C 1), whereas two isomers of La(C 3 H 4) are a four-membered metallacycle La(CHCHCH 2) (Iso 1, C 1) and a three-membered ring La(CHCCH 3) (Iso 2, C s). The ground electronic state of each radical is a doublet and that of the singly charged cation is a singlet. The remaining two electrons that are associated with the isolated La atom or ion are spin paired in a molecular orbital that is bonding combination between a La 5d orbital and a π* antibonding orbital of the C 5 H 6 or C 3 H 4 fragment. For the 1,4-pentadiene reaction, the formation of the six-membered metallacycle La(C 5 H 6) involves La addition to a C=C double bond, La insertion into two C(sp3) H bonds, and concerted H 2 elimination, whereas the formation of the three- and four-membered La(C 3 H 4) rings involves two hydrogen migrations followed by C C bond breakage to eliminate an ethylene molecule. For the 1-pentyne reaction, the formation of each species requires isomerization of a La(1-pentyne) adduct to a La insertion species and then proceeds with the same elemental steps as those for the diene reaction. Graphical abstract Image 1 Highlights • La-mediated C-H and C-C bond activation of 1,4-pentadiene and 1-pentyne are studied with threshold ionization spectroscopy • Adiabatic ionization energies and vibrational frequencies are accurately measured for La(C 5 H 6) and La(C 3 H 4). • A six-membered lanthanacycle is identified for La(C 5 H 6), while three- and four-membered rings are determined for La(C 3 H 4). • Formation pathways of the La-hydrocarbon radicals are investigated by combining the measurements with computations. [ABSTRACT FROM AUTHOR]

Upconverting nanoparticles (UCNPs) composed of NaYF4 and doped with photoactive Yb3+ and Er3+ (NaYF4:Yb/Er) are highly desirable for many biological applications, but obtaining stable dispersions of UCNPs is challenging. Traditional synthetic methods often use complicated synthetic steps, produce toxic side products, and require post modifications to make UCNPs more dispersible in aqueous solutions. In this study, we demonstrate that laser ablation in liquid (LAL) is a novel approach to synthesize water-dispersible and -stable UCNPs with advantages of particle-size tuning, in situ coating of UCNPs with capping agents, no use of toxic or high boiling point solvents, and short reaction times. NaYF4:Yb/Er UCNPs were produced through LAL of annealed targets using water as the liquid, and their compositions and properties were investigated at a laser fluence of 0.57 J cm−2–6.22 J cm−2 by direct capping with citric acid and ethylene glycol and by comparing with the UCNPs prepared from the traditional hydrothermal method. Low laser fluences produced polydisperse particles consisting of no photoactive species through a thermal evaporation mechanism, while high laser fluences generated UCNPs with more uniform morphologies and compositions similar to the target material by an explosive ejection mechanism. The inclusion of capping agents during LAL allowed for direct coating of the UCNP surface without the need of post modifications, and the concentrations of capping agents affected the UCNP photoluminescence lifetimes. As compared to the hydrothermal method, the LAL-prepared samples showed better size control and no degradation of the capping agents. [ABSTRACT FROM AUTHOR]

La atom reactions with 1-pentene and 2-pentene are carried out in a laser-vaporization molecular beam source. The two reactions yield the same metal-hydrocarbon products from the dehydrogenation and carbon–carbon bond cleavage of the pentene molecules. The dehydrogenated species La(C5H8) is the major product, whereas the carbon–carbon bond cleaved species La(C2H2) and La(C3H4) are the minor ones. La(C10H18) is also observed and is presumably formed by La(C5H8) addition to a second pentene molecule. La(C5H8) and La(C2H2) are characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of each species from the two reactions exhibit the same transitions. Adiabatic ionization energies and metal-ligand stretching frequencies are determined for the two species, and additional methyl bending and torsional frequencies are measured for the larger one. Five possible isomers are considered for La(C5H8), and a C1 metallacyclopentene (Iso A) is identified as the most possible isomer. La(C2H2) is confirmed to be a C2v metallacyclopropene. The ground electronic state of each species is a doublet with a La 6s1-based electron configuration, and ionization yields a singlet state. The formation of the lanthanacyclopentene includes La addition to the C=C double bond, La insertion into two C(sp3)—H bonds, and concerted dehydrogenation. For the 2-pentene reaction, the formation of the five-membered ring may also involve 2-pentene to 1-pentene isomerization. In addition to the metal addition and insertion, the formation of the three-membered metallacycle from 1-pentene includes C(sp3)—C(sp3) bond breakage and hydrogen migration from La to C(sp3), whereas its formation from 2-pentene may involve the ligand isomerization. [ABSTRACT FROM AUTHOR]

La atom reactions with 1-butene, 2-butene, and isobutene are carried out in a laser-vaporization molecular beam source. The three reactions yield the same La-hydrocarbon products from the dehydrogenation and carbon-carbon bond cleavage and coupling of the butenes. The dehydrogenated species La(C4H6) is the major product, which is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectrum of La(C4H6) produced from the La+1-butene reaction exhibits two band systems, whereas the MATI spectra produced from the La+2-butene and isobutene reactions display only a single band system. Each of these spectra shows a strong origin band and several vibrational progressions. The two band systems from the spectrum of the 1-butene reaction are assigned to the ionization of two isomers: La[C(CH2)3] (Iso A) and La(CH2CHCHCH2) (Iso B), and the single band system from the spectra of the 2-butene and isobutene reactions is attributed to Iso B and Iso A, respectively. The ground electronic states are 2A1 (C3v) for Iso A and 2A′ (Cs) for Iso B. The ionization of the doublet state of each isomer removes a La 6s-based electron and leads to the 1A1 ion of Iso A and the 1A′ ion of Iso B. The formation of both isomers consists of La addition to the C=C double bond, La insertion into two C(sp3)—H bonds, and H2 elimination. In addition to these steps, the formation of Iso A from the La+1-butene reaction may involve the isomerization of 1-butene to isobutene prior to the C—H bond activation, whereas the formation of Iso B from the La+trans-2-butene reaction may include the trans- to cis-butene isomerization after the C—H bond activation. [ABSTRACT FROM AUTHOR]

Mice are the most frequently used animals in pharmacokinetic studies; however, collecting series of blood samples from mice is difficult because of their small sizes and tiny vessels. In addition, due to the small sample size, it is problematic to perform high required quantification. Thus, present work aims to find an effective strategy for overcoming these challenges using trans-resveratrol as a tool drug. Based on the idea of a joint technology, the capillary microsampling (CMS) was chosen for blood sample collection from mice after delivery of trans-resveratrol (150 mg/kg) by gavage, and a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the determination of trans-resveratrol and its main metabolites. All the mouse blood samples were exactly collected by CMS without obvious deviation. This provided credible samples for subsequent quantitative analysis. The HPLC-MS/MS method was found to be sensitive, accurate, and repeatable, and the pharmacokinetic parameters for all analytes were comparable with those reported in previous studies. However, the present joint technology offers the advantages of less animal damage, easy for sample preparation, and improved reliability. It has overcome some of the major limitations revealed in previous pharmacokinetic studies in mice and therefore provides a more effective option for future studies. [ABSTRACT FROM AUTHOR]

Copper complexes of 2,2′-bipyridine (22BIPY) and 4,4′-bipyridine (44BIPY) were prepared in a laser-vaporization supersonic molecular beam source and identified by laser photoionization time-of-flight mass spectrometry. Electronic spectra and molecular structures were studied with pulsed-field ionization zero electron kinetic energy (ZEKE) electron spectroscopy, density functional theory (DFT) and second-order Møller-Plesset perturbation (MP2) calculations, and spectral simulations. Adiabatic ionization energies and metal-ligand and ligand-based vibrational frequencies of Cu-22BIPY and Cu-44BIPY were measured from the ZEKE spectra. Ground electronic states and molecular structures of the two complexes were determined by comparing the spectroscopic measurements with the theoretical calculations. The ground state of Cu-22BIPY (2B1, C2 v) has a planar bidentate structure with Cu binding to two nitrogen atoms and two pyridine molecules in the cis configuration. The ground state of Cu-44BIPY (2A, C2) has a monodentate structure with Cu binding to one nitrogen and two pyridines in a twisted configuration. The ionization energy of Cu-22BIPY is considerably lower and its bond energy is much higher than that of Cu-44BIPY. The different ionization and dissociation energies are attributed to the distinct metal binding modes of the two complexes. It has been found that the DFT calculations yield the correct structures for the Cu-22BIPY complex, whereas the MP2 calculations produce the best structures for the Cu-44BIPY complex. [ABSTRACT FROM AUTHOR]

During the war, the time windows is the essential property of combat missions. Combining with the development of battle plan, this paper illustrated the inherent hierarachy of it and relationships between task and plan in every command level; on the topic of the joint operational plans, for the first established mathematical model with time windows, and solved it by using extended multidimensional dynamic list scheduling (EMDLS). Experimental results suggest that the solution is reasonable and practicable. [ABSTRACT FROM AUTHOR]