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Split theta-shaped nanocavities composed of an elliptical disk embedded in a nonconcentric split ring are theoretically investigated by the finite-difference time-domain method. Symmetric and antisymmetric mode-based Fano resonances are both formed, due to the interference between the bright mode of the cavity and two types of multipole modes of the split ring, and experience different changes through adjusting the degree of symmetry breaking via an asymmetry of the ring width and displacement of the disk. As the cavity remains symmetrical with respect to the axis of the split ring, only the symmetric Fano resonances are observed. Further breaking the cavity symmetry, the antisymmetric Fano resonances appear and increase, while symmetric ones decrease. When the overall degree of symmetry breaking becomes larger due to an increasing offset of the disk relative to the asymmetric ring, this change trend becomes more complicated, and some Fano resonances are suppressed or enhanced again. Our work demonstrates that the proposed cavities with tunable Fano line shape could be used as platforms for multiwavelength biochemical sensors and enhanced spectroscopies.

This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology and microstructural analyses, it revealed that the rolling contact fatigue wear mechanism played a significant role under the low slip ratio, but the dominant wear mechanism transferred to the abrasive wear at the high slip ratio. Meanwhile, the bainitic steel specifically presented worse wear resistance under the abrasive wear mode. Compared with the influence of a slip ratio, the increase in contact stress led to severer plastic flows and contributed to the propagation of cracks. In addition, the contact stress and slip ratio had the opposite effect on the friction coefficient, that is, the friction coefficient of bainitic steels behaved the inverse proportion with the contact stress, but positive proportion with the slip ratio. At last, the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism.

The synthesis of polyethylenes with precise branching, especially long-chain branching (LCB), using ethylene monomer as a single feedstock is of a significant academic and industrial interest. On the basis of the ortho-aryl effect, a series of α-diimine nickel complexes with monoaryl-substituted anilines has been designed and prepared for the synthesis of the polyethylenes with controlled branching. The introduction of the ortho-aryl on aniline moieties enhanced the branching control ability of the α-diimine nickel catalysts. A different mechanistic model was proposed to interpret the presence of methyl and LCB but absence of other short branches in the obtained polyethylenes. LCB was formed by ethylene insertion into the primary Ni-alkyl species originating from nickel migration to methyl terminal of the growing chain because of restricted ethylene insertion into secondary Ni-alkyl species with an α-ethyl or a bulkier alkyl group.

Air layer exists between glass covers and cells in most building-integrated photovoltaic/thermal (BIPV/T) systems. This layer significantly reduces heat loss and improves the thermal efficiency of BIPV/T systems. However, the frame border that supports the glass cover casts a shadow over cells near the frame according to the air layer thickness, system orientation and location of the sun, thereby affecting photovoltaic performance. This study aims to find out the effect of such air layer on thermal and photovoltaic performance of BIPV/T systems. The distribution of frame shadows and photovoltaic loss caused by such shadows is analyzed. Then thermal and photovoltaic performance of BIPV/T system with different air layer thicknesses is evaluated. The influences caused by the air layer thickness, orientation of the BIPV/T system, solar altitude, and solar azimuth are analyzed. An approach is presented to evaluate the annual performance of the BIPV/T system. The results show that the frame shadow reduces system photovoltaic efficiency to 2.6% (normal efficiency, 13.0%) in the worst case scenario in Hefei (E117°17′, N31°52′). The maximum annual electrical loss caused by the frame shadow is 70.15 kWh/m 2 at an azimuthal angle of −45°. The quantity of total outputs increases with increasing air thickness. But the maximum comprehensive outputs are 359.95 kWh at 20 mm air thickness.

We numerically simulated dynamic propagation of in-phase and out-of-phase finite-energy Airy pulses in anomalous regions of optical fibers and analyzed the effects of cubic–quintic (CQ) competing nonlinearity and separation parameter on evolution properties. Numerical results showed entirely different effects of quintic nonlinearity on in-phase and out-of-phase Airy pulses that vary with different separation parameters. For in-phase Airy pulses, a central quasi-soliton pulse is shed from all finite-energy Airy pulses when separation parameter is certain. CQ competing nonlinearity exhibits profound effects on propagation dynamics of soliton pulses. However, for out-of-phase Airy pulses, two quasi-soliton pulses and more dispersion wave pulses are symmetrically shed from the main lobe of out-of-phase Airy pulses. CQ competing nonlinearity slightly impacts evolution of out-of-phase Airy pulses depending on peak intensity, which varies with propagation distance and unlike in cases of in-phase Airy pulses.

Additional file 1: Table S1. Detection of rubella IgM in the clinical serum obtained by the antigen-labeled Au@Pt@SiO2 nanozyme-based ELISA.

A plasmonic nanostructure composed of a displaced elliptical disk in a nonconcentric split ring is proposed and investigated theoretically by the finite difference time domain method. The simulated scattering spectra and electric field distributions reveal that multiple Fano resonances can be formed due to the destructive interference of the longitudinal dipole mode of the disk and multiple multipole magnetic modes of the split ring. It is also found that the spectral position of each Fano dip is insensitive to the offset caused by moving the disk in either direction, but the depth varies to a different extent. When the disk moves parallel to the split, it is very suitable for the generation and evolution of the symmetric Fano resonance, particularly the structural symmetry of the split ring is further broken. As the disk moves perpendicular and closer to the split, the depth of each antisymmetric Fano resonance increases, while the appeared symmetric ones weaken. Such a nanostructure may be used as a potential platform for spectral line shaping and multiwavelength bio-chemical sensing.

The plasmon properties of the concentric cavity consisting of a semi-disk inside a thin ring are theoretically investigated by the finite difference time domain and plasmon hybridization methods. According to the simulated absorption and scattering spectra, electric field distributions and charge diagrams, multiplar Fano resonances are successfully generated, mainly due to the coupling between the dark multipolar modes and the bright dipolar mode originating from the hybridization between the primitive modes of the semi-disk and the ring. Moreover, the intensities and spectral positions of the Fano resonances can be manipulated by modifying the geometric parameters of the cavity. The cavity for potential use as a multi-wavelength biochemical sensor is evaluated with the refractive index sensitivity and figure of merit.

Activated carbon aerogel spheres (A-CAS) were successfully prepared by imposing KOH activation on aerogel spheres. It was found that the activation treatment did not destroy the order of the surface of the carbon aerogel spheres (CAS), but it improved the pore structure and adsorption performance of the products. With increasing burn-off, the amount of mesopores first decreased and then increased, with the amount of micropores continuously increasing. The highest measured BET surface area and micropore surface area reached 1198 and 786 m2/g, respectively. The adsorption capacity of benzene organic vapour on the A-CAS is more than eight times as large as that on CAS.

A series of unsymmetrical α-diimine nickel complexes with various backbones and substituted aniline moieties were synthesized and characterized. The crystallographic analysis of the nickel complexes confirmed the existence of meso- and rac-configuration in solid structure. Nickel complexes after activation by MAO were screened for ethylene polymerization to evaluate backbone substituent effect on synthesis of bimodal PE. Acenaphthyl nickel complex with planar backbone afforded a bimodal PE with a broad polydispersity, whereas camphyl nickel complex with rigid and bulky backbone afforded a monomodal PE with a narrow polydispersity. Steric effect of aniline moiety for acenaphthyl nickel complex was also examined, and bimodal PE with dominant high-molecular-weight fraction was obtained by modifying substituents on aniline moiety.

On the basis of different approaches for modifying α-diimine palladium catalysts, a series of methyl chloride palladium complexes with various α-diimine ligand backbones were synthesized and charac...

Differs from other planets in the Solar System, the Venus has a retrograde and long-period rotation. To ex-plain the special spin of the Venus, mechanisms such as core mantle friction inside planet[1], atmospheric tide[2-7], or twain effects together[8-11], and impact with a giant object[12,13] have been suggested. These mecha-nisms, however, need specific initial conditions with a remote probability [3,5]. The slow spin of Mercury cannot be explained very well. One viewpoint is that the unusual spins of Venus and Mercury might be naturally evolved from similar initial states by interaction with interplanetary matter during long-time evolu-tion. Based on the theory of planet formation and the orderliness of planetary distance, we discuss the possi-bility that the radial density distribution of interplanetary matter is undulated, and the wave function satisfies the formal Schrodinger equation. We calculate the evolution of planet spins under the effect of interplanetary matter during planets revolution and rotation. The results show that planets can naturally evolve to the cur-rent state (particularly the negative spin of the Venus) given the similar initial quick and positive spins.

On the basis of the strategy of promoting thermostability of α-diimine nickel catalyst by ligand backbone framework, a series of α-diimine nickel(II) complexes with bulky camphyl or diaryl-substituted backbones, [2,6-(R2)2C6H3−N═C(R1)−C(R1)═N−2,6-(R2)2C6H3]NiBr2 (1a, R1 = Ph, R2 = CH3; 2a, R1 = 4-methylphenyl, R2 = CH3; 3a, R1 = 4-fluorophenyl, R2 = CH3; 4a, R1 = camphyl, R2 = CH3; 4b, R1 = camphyl, R2 = i-Pr), were synthesized and used as catalyst precursors for ethylene polymerization. Crystallographic analysis revealed that the bulky camphyl backbone has a valid steric-effect on the nickel center by blocking the axial site for the metal center and suppressing the potential rotation of the CAr−N bond. Ethylene polymerizations catalyzed by these nickel α-diimine complexes activated by MAO were systematically investigated and the influences of the substituted backbones as well as reaction temperature on the catalytic activity, molecular weight and branching structure of the polymers were evaluated. It was...

A series of new nickel complexes and palladium complexes bearing ortho-phenoxy modified anilido-imine ligands have been synthesized and characterized. X-ray diffraction analyses of the single crystal structures reveal that there are no direct metal–O interactions in all of the complexes. The steric hindrance of complexes has an importance influence on their coordinated geometries. The bulky complexes with 2,6-diisopropylphenyl substituent exist as a dimers with bromine-bridged structure while those with 2,6-dimethylphenyl or phenyl substituents adopt a distorted tetrahedral geometry with four nitrogen atoms of two anilido-imine ligands. The nickel complexes exhibited high activity up to 7.33 × 106 g/(mol of Ni · h) and palladium complexes showed very high activity up to 2.63 × 108 g/(mol of Pd · h) for norbornene polymerization with methylaluminoxane as cocatalyst. The nickel catalysts were attempted to polymerize ethylene at atmosphere pressure, however, only oligomers were produced.

Several N-functionalized bis(phosphanyl)amine ligands respectively containing benzyl, furfuryl, thiophene-2-methyl, thiophene-2-ethyl, and 2-picolyl groups (1a–e) were synthesized and characterized. The ligands reacted with (DME)NiBr2 in CH2Cl2 to give their corresponding nickel complexes [Ph2PN(R)PPh2NiBr2] [R = CH2C6H5 (2a), CH2C4H3O (2b), CH2C4H3S (2c), CH2C5H4N (2d), and CH2CH2C4H3S (2e)]. The structures of these complexes were established by single-crystal X-ray crystallography. All these nickel complexes were highly active towards ethylene oligomerization in the presence of methylaluminoxane or Et2AlCl, producing a high content of butene (C4). Especially for 2e, which contains a thiophene-2-ethyl pendant group, the oligomerization products obtained at –40 °C contained 95.9 mol-% C4 fraction with 100 mol-% 1-butene. Over 50 °C, however, these nickel complexes underwent Friedel–Crafts alkylation of toluene with ethylene and the olefin oligomers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A series of nickel(II) complexes with different steric and electronic substituted 2-pyridylbenzamidine ligands, [2,6-iPr2C6H3–N C(R1)–NH–(5-R3, 6-R2)Py]NiBr2 (R1 = Ph, R2 = H, R3 = H, 1; R1 = Ph, R2 = H, R3 = NO2, 2; R1 = 4-CH3OC6H4, R2 = H, R3 = H, 3; R1 = 4-CH3C6H4, R2 = Me, R3 = H, 4), have been synthesized in high yield and the solid state structures of 1, 2 and 4 have been crystallographically characterized. Activated with methyaluminoxane (MAO), 1–4 showed moderate turnover frequency (TOF) for ethylene oligomerization in dichloromethane. The influences of the ligand structure on catalytic properties were studied. Complex 2 with an electron-withdrawing group revealed the highest TOF of up to 11.7 × 103 mol ethylene/(mol Ni h). Moreover, the reaction temperature and Al/Ni molar ratio were also examined in detail.

Two new ionic liquid-supported bis-(salicylaldimine) Ni(II) complexes Ni[2-(O)C6H4CH=N(CH2)3(methylimidazole)Br]2 (1) and Ni[3, 5-tBu2-2-(O)C6H2CH=N(CH2)3(methylimidazole)Br]2 (2) have been synthesized and characterized. Ethylene oligomerizations were carried out with these two complexes in biphasic solvent systems consisting of chloroaluminate ionic liquid and n-heptane or toluene under mild reaction conditions. In the presence of diethylaluminum chloride, both complexes 1 and 2 are highly active for ethylene oligomerization. The olefinic products can be easily separated from the catalytic ionic liquid phase by simple decantation, and the nickel catalysts can be reused in successive ethylene oligomerization cycles. GC-MS analyzes showed that the obtained oligomers contained mainly C4, C6, and C8 olefins.

Three new neutral monoamidinate nickel complexes [(2,6-iPr–C6H3)N C(Ar1)–N(Ar2)]Ni(Ph)(PPh3) (1, Ar1 = phenyl, Ar2 = 2,6-diispropyphenyl; 2, Ar1 = p-tolyl, Ar2 = 2,6-dimethylphenyl; 3, Ar1 = p-tolyl, Ar2 = pentafluorophenyl) have been synthesized and characterized. The molecular structure of 3 has been determined by X-ray diffraction analysis. The nickel complexes activated with MAO were found to exhibit very high activity, up to 1.94 × 107 g PNBE/(mol Ni h), for vinyl-addition polymerization of norbornene and oligomerize ethylene producing a mixture of dimers and trimers with a moderate turnover frequency.

A novel titanium(IV) dimeric complex [(OC(Ph)HC(Ph)O)TiCl(μ-OCH(Ph)C(Ph)(n-Bu)O)]2 (1) was synthesized and characterized, and its catalytic behaviors toward homo- and copolymerization of ethylene (E) and norbornene (NB) were also investigated. X-ray diffraction analysis of single crystal structure revealed that the titanium complex features a binuclear and six-coordinate, pseudo-octahedral geometry around titanium metal center with oxo-bridge in the solid state. Activated with methylalumoxane (MAO), the titanium complex exhibited good activities for the homopolymerizations of ethylene and norbornene with long lifetime and produced high-molecular weight linear PE and vinyl-type PNB, respectively. E–NB copolymers with high-molecular weight and high NB incorporation content could be also obtained by this catalyst. The incorporation of NB in the E–NB copolymers could be controlled by varying monomer ratio and reaction temperature. 13C NMR analyses showed that the microstructures of the E–NB copolymers are predominantly alternated and isolated NB units, but the dyad and triad sequences of NB unit could be detected in the copolymers with high NB incorporation. The monomer reactivity ratios of the copolymerization were measured to be rE = 6.0, rN = 0.05 at 30 °C.

A series of new N,N,S tridentate nickel(II) complexes [(ArN = CHC6H4NPh-2-SPh)NiBr] (Ar = 2,6-diisopropylphenyl, 1; Ar = 2,6-dimethylphenyl, 2; Ar = Ph, 3) and palladium(II) complexes [(ArN = CHC6H4NPh-2-SPh)PdCH3] (Ar = 2,6-diisopropylphenyl, 4; Ar = 2,6-dimethylphenyl, 5; Ar = Ph, 6) were synthesized and characterized. X-ray diffraction analyses of the single-crystal structures revealed that tridentate complexes 1, 2, 4, 5, and 6 featured a distorted square-planar coordination of the central metal. Compared to the bidentate metal complexes bearing anilido–imine ligands, the N,N,S tridentate metal complexes showed better stability. In the presence of methylaluminoxane (MAO), nickel complexes 1–3 showed moderate activity toward ethylene oligomerization at atmosphere pressure, but the palladium complexes were inactive. However, the nickel complexes exhibited high activity up to 8.20 × 106 g/(mol of Ni) h and palladium complexes showed very high activity up to 2.68 × 108 g/(mol of Pd) h toward norbornene polymerization with MAO as cocatalyst. The obtained polynorbornenes are vinylic addition polymers with high molecular weights. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A series of 2-aminopyridine Ni(II) complexes bearing different substituent groups {(2-PyCH 2 NAr)NiBr, Ar = 2,4,6-trimethylphenyl (3a), 2,6-dichlorophenyl (3b), 2,6-dimethylphenyl (3c), 2,6-diisopropylphenyl (3d), 2,6-difluorophenyl (3e); (2-PyCH 2 NHAr) 2 NiBr 2 , Ar = 2,6-diisopropylphenyl (4a)} have been synthesized and investigated as precatalysts for ethylene polymerization in the presence of methylaluminoxane (MAO). High molecular weight branched polymers as well as short-chain oligomers were simultaneously produced with these complexes. Enhancing the steric bulk of the ortho-aryl-substituents of the catalyst resulted in higher ratio of solid polymer to oligomer and higher molecular weight of the polymer. With ortho-haloid-substitution, the catalysts afforded a product with low polymer/oligomer ratio (3b) and even only oligomers (3e) in which C 14 H 28 had the maximum content. Compared with complex 3d containing ionic ligand, complex 4a containing neutral ligand exhibited obviously low catalytic activity for ethylene polymerization. The molecular weight, molecular weight distribution, and microstructure of the resulted polymer were characterized by gel permeation chromatography and 13 C NMR spectrogram.

The measuring technique for characteristics of localized surface plasmon resonance (LSPR) effect of metallic nanostructures is studied in this paper. A simple apparatus for measuring the LSPR properties is designed and developed with the help of an integrating sphere using a single light beam; the sphere inner wall is coated with Teflon and has three ports used for sample, detector and incident light input. By changing the angle and position of the integrating sphere and the sample in the light path, the forward, backward and scattering spectroscopy of the metallic nanostructures can be obtained indicating that the absorption and scattering properties associated with the LSPR effect can be distinguished. It is founded that no matter what measurement form, the spectrum can reflect the general LSPR property, despite there is difference in the spectral intensity and peak. The measuring technique present in this paper may be an alternative way for the characterization of the LSPR effect.

Bulky 2-pyridinemethanamine nickel complex activated by MAO was used as a catalyst to conduct longstanding living ethylene polymerization under atmospheric pressure to produce branched polyethylene.