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The core–shell Ni@C submicrospheres were fabricated by sintering method and combined with PVDF to prepare Ni@C/PVDF composite, which possessed optimal wave absorption property with RL min of −71.32 dB and EAB of 5.62 GHz at 1.95 mm.

The perfect control over the constituent and architecture of porous nanomaterials is still a significant challenge in developing high performance electromagnetic wave absorption materials. In this work, we have designed and prepared a novel lightweight electromagnetic wave absorption material with the combination of hollow structure and bimetallic constituents by the thermal decomposition of metal−organic framework (MOF) ZIF-67. We found that by introducing additional metal Nickle into the porous Co/C composites, the CoNi/C-800-PVDF nanocomposite could yield an excellent reflection loss of −61.02 dB at 13.68 GHz and simultaneously possess effective absorbing bandwidth of 5.2 GHz with lower filler loading as 10 wt%, which corresponding to a less absorber thickness of 2 mm. These results demonstrate that the synergistic effects between the bimetallic components and hollow structure of novel CoNi/C composite optimize impedance matching, and thus improve the absorption performance greatly. The properties of specific surface area, interface polarization, dipole polarization, ferromagnetic resonance, eddy current loss and multiple scattering are investigated to further explain the high performance of materials.

A two-dimensional carbon-based composite material loaded with magnetic nanoparticles Fe3C (CN–Fe3C) was successfully designed and prepared to ensure the dielectric loss and magnetic loss effect occur simultaneously. The impedance matching of the material is better realized, and the absorbing performance is improved. The loading of ferromagnetic Fe3C effectively improves the magnetic properties of the composites. When the filling amount is only 10 wt%, the composite can achieve a reflection loss value of −46.78 dB at 13.53 GHz, and the effective absorption bandwidth is as high as 5.01 GHz. The excellent absorbing performance is mainly due to the enhancement of interfacial polarization and the synergistic effect between the dielectric properties of carbon materials and the magnetic properties of Fe3C. CN–Fe3C/PVDF also shows good electromagnetic shielding effectiveness. This work has developed new ideas for designing and preparing “thin”, “light”, “wide”, and “strong” two-dimensional carbon-based composite absorbing materials.

Flotation is often employed to separate valuable natural minerals and gangue minerals. However, few studies have been conducted on artificial mineral flotation. Anosovite, the primary mineral in titanium slag, is a typical artificial mineral that can be enriched by flotation. In the present work, flotation behavior and adsorption mechanism of anosovite in salicylhydroxamic acid (SHA) solution were studied. The influence of pH and SHA dosage on anosovite flotability was investigated. Micro-flotation test results show that a pH range of 7–8.5 is available for SHA to collect anosovite. A maximum recovery of 93.26% can be obtained with SHA dosage of only 4×10−5 mol/L. In addition, TOC, zeta potential, FTIR, SEM-EDS, and XPS analyses were used to study the adsorption mechanism. Results demonstrated that SHA adsorption is governed by chemisorption. XPS studies further suggested that chemical adsorption occurred at the Ti sites on the anosovite surface.

Reduced graphene oxide (rGO)/Ni hybrids with different mass ratio are successful synthesized in order to tune the microwave absorption together with the electromagnetic shielding performance. By properly adjusting the permittivity and permeability derived from different contents of the rGO and Ni, an rGO/Ni composite with excellent microwave absorption properties is obtained. An optimal reflection loss value of −39.03 dB at 13 GHz is achieved for the composite with rGO/Ni ratio of 1:1, and the bandwidth less than −10 dB can reach up to 4.3 GHz (from 11 to 15.3 GHz) with a thickness of 2.0 mm. Furthermore, the composite with rGO/Ni ratio of 4:1 shows superior electromagnetic shielding performance as high as 52 dB, which far surpasses the best value for most carbon-based materials. Fundamental mechanisms for absorbing and shielding performance are discussed.

Conjugated polymer (CP) multilayer films with higher conductivity have been constructed by electric-field induced LBL assembly technique. Single component has been selected in the alternate deposition process, which not only provides a universal approach for CP films fabrication but also broadens the applicable scope of LBL assembly technique.

The electronic properties and optical properties of doped β-Bi2O3 have been studied using spin-polarized density function theory (DFT) with the aim of realizing the photocatalytic hydrogen generation under visible light irradiation. The results show that IIIA elements (Al, Ga, In and Tl) mono-doping increase the necessary redox potentials in energy for water splitting, but the increasing of band gap decreases the visible light absorption. Moreover, co-doping in β-Bi2O3 can overcome this problem by increasing the light absorption and simultaneously realizing water splitting by sunlight. The N/Al and N/Ga co-doped β-Bi2O3 introduce the delocalized band, which extend the light absorption but has limited benefit for photocatalytic activity. Importantly, N/In and N/Tl co-doping shift the mid-gap states toward the valence band edge to create an extend valence density of states, which can improve the light absorption. In particular, N/In co-doping leads to the narrowed band gap and a stronger potential for photocatalytic activity toward hydrogen evolution from water, which may play an important role in the development of bismuth oxides for more effective utilization of the solar spectrum for fuel production.

The improved performance of a wavelength-tunable arrayed waveguide grating (AWG) is demonstrated, including the crosstalk, insertion loss and the wavelength tuning efficiency. A reduced impact of the fabrication process on the AWG is achieved by the design of bi-level tapers. The wavelength tuning of the AWG is achieved according to the thermo-optic effect of silicon, and uniform heating of the silicon waveguide layer is achieved by optimizing the heater design. The fabricated AWG shows a minimum crosstalk of 16 dB, a maximum insertion loss of 3.91 dB and a wavelength tuning efficiency of 8.92 nm/W, exhibiting a ∼8 dB improvement of crosstalk, ∼2.1 dB improvement of insertion loss and ∼5 nm/W improvement of wavelength tuning efficiency, compared to our previous reported results.

Inspired by the birch bark, which has multilayered structures, we fabricated layer-by-layer (LbL) assembled montmorillonite (MMT) and poly(p-aminostyrene) (PPAS) nanocomposites on cotton fiber curved surfaces to provide protection from atomic oxygen (AO) erosion. The multilayer coated fibers had high flexibility, uniformity, defect free, ease of preparation and low cost. The AO erosion durability has been dramatically enhanced which was evidenced by testing in the ground-based AO effects simulation facility. And the dimension and surface morphologies of the fibers observed by SEM had few changes, indicating excellent AO erosion resistant ability of the coatings. These results provide us a new method to design fibrous materials exposed directly in low earth orbit environment.

A simple solution route was developed to fabricate monodisperse wurtzite ZnO nanorods. The as-prepared samples were 5 μm in length and 70–100 nm in diameter. The crystallinity, morphology, and structure of the rod-like ZnO microcrystals were examined. The crystal phases and the microstructure of the nanorods were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Room- and low-temperature photoluminescence (PL) and Raman spectra were employed to investigate the surface states of the samples. The deep-level emission band was barely observable at both room and cryogenic temperatures.

Quantum chemical studies for the nine N 1 3 isomers with low spin were carried out at the UHF/6-31G*, UB3LYP/6-31G* and UMP2/6-311G* levels of theory. The most stable N 1 3 isomer is structure 1 with C 2 v symmetry, whichcontains two separated pentazole rings connected by three nitrogen atoms. The results show that structures 1, 2, 3, 4 and 5 which are composed of the pentazole ring are more stable than the open chain structure 6 and structures 8 and 9 which contain the four- and six-membered rings. This suggests that the pentazole ring is a fundamental stable structural unit, which is applicable not only for the even-numbered nitrogen clusters, but also for the large odd-numbered clusters.

Reduced graphene oxide (RGO)/Co

The authros developed a new approach to preparing the Au@SiO2 core-shell nanostructure. The morphology and stability of the composite were characterized by the UV-Vis absorption spectroscopy and transmission electron microscopy (TEM) methods. The stable SERS spectra were obtained from the PMBA-functionalized Au@SiO2 composite. In addition, the authros succeeded in adjusting the thickness of SiO2 layer by controlling the precursor consumption. The stability of Au@SiO2 in basic solution was studied and the results showed that the SiO2 shell was facile to be etched. The present work may provide a reference and gist for research on the preparation, storage and application of Au@SiO2.

We perform first-principles computational tensile and compressive tests (FPCTT and FPCCT) to investigate the intrinsic bonding and mechanical properties of a γ-TiAl intermetallic compound (L 1(0) structure) using a first-principles total energy method. We found that the stress-strain relations and the corresponding theoretical tensile strengths exhibit strong anisotropy in the [001], [100] and [110] crystalline directions, originating from the structural anisotropy of γ-TiAl. Thus, γ-TiAl is a representative intermetallic compound that includes three totally different stress-strain modes. We demonstrate that all the structure transitions in the FPCTT and FPCCT result from the breakage or formation of bonds, and this can be generalized to all the structural transitions. Furthermore, based on the calculations we qualitatively show that the Ti-Al bond should be stronger than the Ti-Ti bond in γ-TiAl. Our results provide a useful reference for understanding the intrinsic bonding and mechanical properties of γ-TiAl as a high-temperature structural material.

By in situ reduction of Ag(+) ions pre-dispersed inside thermosensitive microspheres of poly[(N-isopropylacrylamide)-co-(methacrylic acid)] (P(NIPAM-co-MAA)), a 3D copolymer-supported network of silver nanoparticles is created and extensively characterized by surface-enhanced Raman scattering (SERS). The effective dispersion and the suitable density of the silver nanoparticles in the composite microspheres are demonstrated by the thermal-induced SERS signal and its high reproducibility during thermocycling. When the temperature of the system increases above 32 °C, spatial separation of the silver nanoparticles decreases and the numbers of Ag nanoparticles and P(NIPAM-co-MAA) microspheres under illumination spot increase as a result of the shrinkage of the P(NIPAM-co-MAA) chains, leading to the ramp of the SERS effect. By means of the high reversibility of the thermosensitive phase transition of the P(NIPAM-co-MAA) microspheres, SERS activity of the silver nanoparticle network embedded in the microsphere can be well controlled by thermal-induced variation of special separation.

High-quality ZnO thin films were grown by plasma-assisted molecular beam epitaxy (P-MBE) on Al2 O3 (0001) substrate with a low temperature ZnO buffer layer. Structural and optical characterization were studied for ZnO thin films. Only a peak at (0002) were observed in the X-ray reflectivity (XRD) spectra with the full-width at half maximum (FWHM) value 0.18 degrees, and two peaks 1LO (579 cm(-1)) and 2LO (1 152 cm(-1)) were detected in the resonance Raman scattering spectra at room temperature. These results indicated that ZnO thin films had single orientation of c axis and high-quality of crystal wurtzite structure. The absorption of free-exciton and exciton-LO phonon appeared in the absorption spectra, which confirmed that the exciton state in the ZnO thin films were stable even at room temperature. And the energy spacing between these two peaks is 71.2 meV, corresponds to the longitudinal optical phonon energy of 71 meV of ZnO. Besides, from the photoluminescence spectra, no defect-related deep emission were observed, but just a remarkable free-exciton emission located at 376nm were obtained at room temperature, it proved that the ZnO thin films had high-quality but low density of defect.

The structures and stabilities of eleven N13 + and N13 − isomers have been investigated with second-order Moller–Plesset (MP2) and density functional theory (DFT) methods. Five N13 + isomers and six N13 − isomers are all reasonable local minima on their potential energy hypersurfaces. The most stable N13 + cation is structure C-2 with C2v symmetry, which contains a pentazole ring and two N4 open chains. It is different from those of the N7 + and N9 + clusters, but similar to the N11 + cluster. Meanwhile, the most stable N13 − structure A-2 is composed of a pentazole ring and a six-membered ring connected by two nitrogen atoms. It is not only different from those of the N7 − and N9 − clusters, but also from the N11 − cluster. The decomposition pathways of structures C-2 and A-2 were investigated at the B3LYP/(aug)-cc-pVDZ level. From the barrier heights of the structures C-2 and A-2 decomposition processes, it is suggested that C-2 is difficult to observe experimentally and A-2 may be observed as a short-lived species. Figure Optimized geometrical parameters of N13 + isomer C-2

Recent experiments indicated that disorder effect in DNA may lead to a transition of the charge transport mechanism from band resonant tunnelling to thermal activated hopping. In this letter, based on Mott's variable-range hopping theory we present a kinetic study for the charge transport properties of DNA molecules. Beyond the conventional argument in large-scale systems, our numerical study for finite-size DNA molecules reveals a number of unique features for (i) the I-V characteristics, (ii) the temperature and length dependence, and (iii) the transition from conducting to insulating behaviors.