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The Debye empirical formulas are often used for the description of the dispersion characteristics of common media, such as biological tissues, water, and soil. In order to reconstruct their frequency‐related electrical properties, a multi‐frequency contrast source inversion (CSI) method is modified from the direct estimation of the contrast between Debye scatterers and background medium, into the reconstruction of three kinds of Debye model parameters, namely, the optical relative permittivity, relative permittivity difference, and static conductivity. Through three two‐dimensional (2D) benchmark numerical experiments, detailed comparisons between the results by the improved CSI method, and those by the frequency hopping (FH) technique, single frequency subspace‐based optimization method (SOM) with deep learning (DL), multi frequency (MF) dispersive SOM, and time‐domain inverse scattering (TDIS) approach, show preliminarily that the modified CSI (M‐CSI) method is feasible and robust, and that it exhibits acceptable compromise performance by the comprehensive consideration of convergence characteristics, positioning accuracy, reconstruction errors, and computational efficiency. Also, the M‐CSI method has been successfully applied to quantitatively reconstruct the internal breast composition in a 2D cancerous phantom extracted from a realistic numerical breast, dielectrically and anatomically. [ABSTRACT FROM AUTHOR]

Infiltration of liquid droplets into dry porous media often occurs in industrial and natural settings, which has been widely modeled as liquid slug flow in capillaries. This work focuses on gravity-driven slug motion in vertically oriented capillary tubes. To model the propagation and evolution of the slug, a mathematical model was set on the basis of Newton’s second law and the law of conservation of mass. The model includes terms like slug’s inertia, deposited film, dynamic contact angle, slug’s advancing and receding menisci hysteresis, and it particularly highlights the direct effect of the trailing film on the change of slug mass. In order to verify this model, experiments on water slug with different lengths of initial slugs were conducted in two Pyrex glass capillaries that are partially wettable. It was found that both the length and the velocity of the slug vary during the slug motion in every case. Then the experimental results were simulated with the established model by carefully presetting two fitting parameters,αaandαh, that are related to the dynamic contact angle at the advancing meniscus and the thickness of the trailing film, respectively. The good agreement between the experimental and theoretical results demonstrates that the present model is capable of describing the unsteady-state dynamics of slugs fall in porous media. [ABSTRACT FROM AUTHOR]

Abstract: In the present paper, a diamine ligand possessing an electron-pulling group 2-phenyl-5-(pyridin-2-yl)-1,3,4-oxadiazole (denoted as PPYO) and its corresponding Re(I) complex Re(CO)3(PPYO)Br were synthesized and carefully characterized. The geometric structure of Re(CO)3(PPYO)Br was analyzed by its single crystal XRD. Theoretical calculation on the crystal suggested that the first few electronic excitations owned a mixed character of metal-to-ligand-charge-transfer (MLCT) and ligand-to-ligand-charge-transfer (LLCT). By doping Re(CO)3(PPYO)Br into a polymer host of poly(vinylpyrrolidone) with electrospinning technique, composite fibers were yielded. The photophysical feature comparison between bulk samples and composite fibers was performed, which suggested that both face-to-face π–π attraction in crystal and the immobilization in PVP matrix could repress the MLCT excited state geometric relaxation, leading to improved emissive parameters including emission blue shift, longer excited state lifetime and better photostability. [Copyright &y& Elsevier]

For various applications of nanoscale surface modification by an Atomic Force Microscope, one would like to maintain the AFM tip near the surface and at an accurately controlled elevated temperature. We study the laser heating of an ordinary AFM silicon tip under ambient conditions, and show that a tightly focused laser beam can heat the tip apex to the desired temperature, while affecting the cantilever quite moderately. We demonstrate that the observation of the shift of the silicon Raman line scattered from the tip is an efficient and accurate way to determine the tip temperature, and we substantiate our observations by theoretically modeling the dynamics of heat accumulation in the tip-cantilever system. For situations where Raman measurements are not feasible, we introduce a new method for estimating the tip temperature by monitoring the mechanical resonance frequency shift of the probe. [ABSTRACT FROM AUTHOR]

Novel double-layer microwave absorbers possessing excellent absorption performances have been designed based on carbon nanofibers (CNFs) and hollow Ba 2 Co 2 Fe 12 O 22 microfibers (Co 2 Y MFs). The electromagnetic wave absorbing characteristics of double-layer absorbers with different layer thicknesses and compositions are investigated over the 2–18 GHz range. Efficient coupling and synergistic effects between the absorbing layer and matching layer lead to a better impedance matching and in turn improve microwave absorption. The optimized double-layer structures exhibit far superior microwave absorbing properties with stronger absorption intensity and wider effective bandwidth compared with the corresponding single-layer ones. When the absorbing layer (1.15 mm in thickness) is filled with 5 wt% CNFs and the matching layer (0.85 mm) is filled with 67 wt% Co 2 Y MFs, a minimum reflection loss (RL) value of −85.5 dB is achieved at 16.1 GHz and the RL less than −10 dB is obtained in the 10.4–18 GHz. Conversely, as the absorbing layer (1.75 mm) is filled with 67 wt% Co 2 Y MFs and the matching layer (0.25 mm) is filled with 5 wt% CNFs, the minimum RL value reaches −68.7 dB at 14.8 GHz and the absorption frequency range with RL values below −10 dB is up to 10 GHz (from 8 to 18 GHz). Moreover, the position, intensity and effective bandwidth of the absorption peaks for the double-layer absorbers can be readily tuned by adjusting the stacking order, the thickness of each layer and total absorber thickness, showing good potential for practical application. • A novel double-layer microwave absorber based on Co 2 Y MFs and CNFs is designed. • The RL min value of −85.5 dB and an effective bandwidth of 10 GHz can be obtained. • Double-layer absorber has much better absorption properties than single-layer one. • Impedance matching characteristics of the absorbers are comparatively analyzed. [ABSTRACT FROM AUTHOR]

An Fe2P nanoparticle (Fe2P NP)-decorated carbon nanofiber (represented as Fe2P@CNF) composite was in situ prepared by electrospinning and subsequent high-temperature treatment. Benefitting from the synergy effect between Fe2P NPs and CNFs, as well as improved interface polarization and impedance matching, the Fe2P@CNF composite exhibits excellent microwave absorption performance relative to pure CNFs, in which the Fe2P@CNF composite with a fill loading of only 10 wt% possesses a minimum reflection loss (RL) of −49.2 dB at 3.0 mm and a maximum effective absorption bandwidth of 6.0 GHz at 2.2 mm. Therefore, this work provides a promising approach for the design and synthesis of an Fe2P@CNF composite with high-performance microwave absorption. [ABSTRACT FROM AUTHOR]

The binary composite, ZnSnO3 microcubes (ZSO MC) homogeneously parceled in an N-doped carbon nanofiber membrane (ZSO@CNFM), was synthesized via a mild hydrothermal, electrospinning and carbonization process as a flexible lithium-ion battery (LIB) anode material. The unique carbon-coating layer architecture of ZSO@CNFM not only plays a crucial role in alleviating the volume change of ZSO MC during lithium ion insertion/extraction processes, but also constructs a three-dimensional (3D) transport network with the help of interconnected carbon nanofibers (CNFs) to ensure the structural integrity of the material and promote the electrochemical reaction kinetics. Due to its good flexibility characteristics, the as-prepared ZSO@CNFM can be directly adopted as an anode material for LIBs without the use of copper foil, conductive carbon black and any binder. Electrochemical surveying results manifest that the optimal ZSO@CNFM electrode displays excellent cycling stability (582.6 mA h g−1 after 100 lithiation/delithiation cycles at 100 mA g−1), high coulombic efficiency (CE, 99.6% at 100th cycles), and superior rate performance (349.5 mA h g−1 at 2 A g−1). The good electrochemical properties can be ascribed to the synergistic effect of the high theoretical specific capacity of ZSO MC, favourable stability of the carbon substrate, the open structure of ZSO@CNFM and the 3D continuous highly conductive framework for rapid electron/ion transfer. [ABSTRACT FROM AUTHOR]

BaSn1−xTixO3 (BSTO, x = 0, 0.25, 0.5, 0.75, 1.0) epitaxial films were deposited on LaAlO3(001) substrates by employing a pulsed laser deposition system. Their composition dependent structure and optical properties were systematically investigated using density functional theory (DFT) calculations. High resolution x-ray diffraction characterization showed that the film lattice parameters decrease linearly with the increase in Ti concentrations, following Vegard's law. Optical property measurements revealed that all films have the optical transmittance of more than 70% in the visible and infrared wavelength range. Interestingly, the bandgap nonlinearity of BSTO films was observed, and the film at Ti doped x = 0.25 has the largest bandgap value of 4.04 eV. The calculated electronic structure and the density of states of BSTO films determined by DFT suggested that the strong hybridization between Sn 5s and Ti 3d orbitals caused the initial expansion of the bandgap, whereas upon further increasing the doping content, Ti 3d orbitals dominated the conduction band, leading to the bandgap reduction. [ABSTRACT FROM AUTHOR]

The development of new generation wearable electronic devices requires the power supply with high power density, long-term cycling performance, and excellent flexibility and mechanical stability that would enhance the durability of flexible devices during use. Herein, we designed a novel strategy for the preparation of flexible self-supporting nanofiber membrane with highly dispersed CoFe 2 O 4 nanoparticles embedded in one-dimensional (1D) N-doped carbon nanofibers (denoted as CFO@NCFM) by electrospinning and subsequent thermal treatment process, which possesses unique hierarchical structure containing zero-dimensional CFO@onion-like carbon nanospheres and cross-linked three-dimensional (3D) fiber network. The rational combination of the nano-sized CFO particles with high theoretical capacity and a N-doped carbon nanofiber conductive skeleton with interconnected 3D open microstructure facilitates the robust penetration of electrolyte into the electrode, improves the overall electrical conductivity of the electrode, shortens the diffusion pathways of Li+ ions, and buffers the volume change of active materials during lithiation/delithiation. As a consequence, the optimized CFO@NCFM exhibits relatively high electrochemical reversible capacity (611.4 mA h g−1 at 100 mA g−1 after 100 cycles) and good cycling stability, as well as satisfactory rate capability. • The flexible CFO@NCFM was prepared by a simple electrospinning method. • Ultrasmall CoFe 2 O 4 nanoparticles (∼8 nm) are uniformly encapsulated in the NCNFs. • The as-prepared CFO@NCFM is directly used as a binder-free electrode. • The formation of three-dimensional conductive network can greatly promote Li+ insertion/extraction kinetics. • The electrode exhibits high capacity, good rate capability and cycling stability. [ABSTRACT FROM AUTHOR]

Microwave absorbers with light weight and excellent microwave absorption performance are urgently needed in the microwave absorption field, which is still a challenge. Herein, N-doped carbon nanofibers decorated with nickel nanoparticles (Ni@CNFs) were synthesized by a facile electrospinning method combined with a two-step heat treatment, in which Ni nanoparticles are uniformly dispersed in carbon nanofibers. Benefitting from the special nanoarchitecture (including Ni nanoparticles encapsulated with graphitic carbon layers and carbon nanotube protrusions anchored on CNFs), three-dimensional conductive networks, the synergistic effect between suitable impedance matching and satisfactory electromagnetic (EM) attenuation ability, a superb comprehensive microwave absorption (MA) property is achieved for the optimal Ni@CNF sample with a rather low filler loading of 5 wt%. The optimal reflection loss (RL) reaches −66.3 dB at a small thickness of 3.1 mm and the maximum effective absorption bandwidth (EAB, RL < −10.0 dB) as wide as 4.56 GHz is obtained at 2.0 mm. This study demonstrates that the carefully designed Ni@CNF composites are superior to many previously reported magnetic carbon-based hybrid absorbers and can be applied as promising candidates for light weight and high-efficiency EM wave absorbers. [ABSTRACT FROM AUTHOR]

Highly dispersed fine FeNi nanoparticles (NPs) encapsulated within carbon nanofibers (FeNi@CNFs) have been fabricated through electrospinning followed by preoxidation and carbonization processes. The influences of FeNi content and filler loading on the electromagnetic (EM) and microwave absorption (MA) properties of the FeNi@CNFs/paraffin wax composites are studied in detail. Benefitting from the special hierarchical microstructure including zero-dimensional FeNi@graphitic carbon core-shell NPs, one-dimensional CNFs with short carbon nanotubes protrusions and three-dimensional conductive network, as well as the synergistic effect between small-sized magnetic FeNi NPs and lightweight dielectric CNFs, the as-prepared FeNi@CNFs samples exhibit excellent MA performances at the ultralow filler loading, in which the FeNi@CNFs-2 with a filling content of only 5 wt% possesses the strongest absorbing intensity and broadest effective frequency bandwidth primarily due to better balance between EM attenuation capability and impedance matching. The minimum reflection loss (RL) reaches −31.3 dB (more than 99.9% MA) at 16.3 GHz with a small thickness of 1.7 mm, and the maximum effective absorption bandwidth (RL < −10 dB) is up to 5.6 GHz (12.0–17.6 GHz) at 1.9 mm, which are superior to those of many previously reported magnetic carbon-based hybrid absorbers. Our results demonstrate that the proper incorporation of small-sized FeNi NPs into CNFs is an efficient and promising strategy to design lightweight and high-performance EM wave absorbers. [Display omitted] • 1D FeNi@CNFs were simply synthesized as high-performance microwave absorbers. • Impedance matching is improved by the introduction of small FeNi nanoparticles. • Optimal reflection loss can reach −31.3 dB at an ultralow filler loading of 5 wt%. • A maximum effective absorption bandwidth of 5.6 GHz can be achieved. [ABSTRACT FROM AUTHOR]

Multilayer absorbers, characterized by their distinctive structures and numerous heterogeneous interfaces, possess the potential to become exceptionally efficient and stable electromagnetic wave absorbers. Herein, we have ingeniously engineered multilayer ZnO/NiCo/C (ZNC) composite absorbers, utilizing a combination of an annealing procedure and atomic layer deposition (ALD) process. From the SEM images, the ZnO layers composed of ZnO nanoparticles (NPs) fabricated via ALD almost completely cover the surface of rice husk-derived carbon and the NiCo NPs residing on the surface. Benefiting from the specific multilayer structure, the well-designed ternary dielectric/magnetic components, and the synergistic interplay between dipole polarization relaxation and interfacial polarization relaxation, coupled with good impedance matching, the ZNC150 and ZNC200 composites exhibit best microwave absorption capacities. Through the precise control of the electromagnetic parameters by the deposition circle modifications, the minimum reflection loss reaches −52.5 dB and the effective bandwidth extends to 4.96 GHz with thin thickness of 1.52 mm. [Display omitted] • The Multilayer ZnO/NiCo/C composites were fabricated by an annealing process and atomic layer deposition. • Specific multilayer structure, well-designed ternary dielectric/magnetic components and superb impedance matching are responsible for excellent properties. • The RL min reaches – 52.5 dB and EAB max achieves 4.96 GHz. • S2 and S3 exhibit RCS values (below –10 dBm2) at almost -90°∼90° with a thickness of 1.94 mm. [ABSTRACT FROM AUTHOR]

La–Mn bimetal oxide nanofibers, used as an adsorbent for the defluoridation of water, were synthesized by an electrospinning and heat treatment technology. The La–Mn bimetal oxide nanofiber adsorbent with a specific surface area of 35.064 m2 g−1 displayed a good defluoridation performance. Both the adsorption kinetics and equilibrium for fluoride (F−) uptake onto La–Mn bimetal oxide nanofibers were investigated. The kinetic studies established that the adsorption attained equilibrium at about 90 min, and the PSO kinetic model was ideal for the kinetic data under 20 and 50 mg L−1. The Langmuir maximum F− uptake was computed to be 189.39 mg g−1 at 308 K and pH 3. A thermodynamic study affirmed a feasible, endothermic, spontaneous and entropy driven process of F− adsorption towards La–Mn bimetal oxide nanofibers at the studied temperature range. Except for the competitive adsorption of PO43− and F−, the presence of NO3−, CO32−, Cl− and SO42− had little effect on fluoride removal. The La–Mn bimetal oxide adsorbent exhibited a good reusability. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The small volume of human dentin available for sample preparation and the local variations in its microstructure present a real challenge in the determination of their mechanical properties. The main purpose of the present study was to develop a new procedure for the preparation and mechanical testing of small-scale specimens of biomaterials such as dentin, so as to probe local mechanical properties as a function of microstructure. Methods: Ultra short laser pulses were used to mill a block of dentin into an array of 16μm size dentin pillars. These could then be individually tested in compression with an instrumented nanoindenter fitted with a 30μm wide flat punch. Results: The laser-based pillar preparation procedure proved effective and reliable. Data was produced for the mechanical properties of a first set of dry dentin micro-pillars. Significance: This novel experimental approach enables the preparation and compression of micron-scale samples with well-defined microstructure. For dentin, this means samples containing a relatively small number of well-defined parallel tubules, with a distinct orientation relative to the applied load. The ability to isolate the separate effects of microstructural parameters on the mechanical properties is of major significance for future substantiation of theoretical models. [Copyright &y& Elsevier]

In this paper, one-dimensional Fe3O4/C core/shell nanorods (NRs) were successfully prepared through magnetic-field-induced (MFI) assembly approach (0.3 T) and subsequent high-temperature carbonization using phenol formaldehyde resin as a carbon source. A serial of examinations were performed thoroughly, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy. The results indicated that phenol formaldehyde resin (PFR) shell was transformed to carbon during the carbonization process and the thickness exhibited significant decrease. The Fe3O4/C core/shell nanoparticles (NPs) were prepared in the same way without magnetic-field-induced (0 T). The electromagnetic properties of Fe3O4/C core/shell composites were measured with coaxial reflection/transmission technique at 2.0–18.0 GHz. Electromagnetic performances indicated that the special structure played a crucial role in determining their dielectric behavior. Compared with the Fe3O4/C core/shell NPs, Fe3O4/C nanorods exhibited higher dielectric constant and higher reflection loss (RL) at a high frequency band with a thin absorber thickness. In detail, the optimal absorption peak value for Fe3O4/C core/shell NRs could reach a strong intensity of -44.1 dB at 1.6 mm, and the effective absorption bandwidth lower than −10 dB is 2.7 GHz (from 11.6 to 14.3 GHz). It is expected that our Fe3O4/C core/shell NRs synthesized via a magnetic field induced in this work could be used as a reference to design novel low-dimensional microwave absorption materials. [ABSTRACT FROM AUTHOR]

A method is proposed to measure short distances using a laser self-mixing velocimeter with low-speed wavelength modulation (2 kHz). The two power spectra obtained in the frequency domain around the rising edge and the falling edge frequencies are employed for estimating the distance and the velocity of a target. The results show that a low-speed wavelength modulation is helpful for the measurement because there are not enough fringes at such distances. The noise caused by the low-speed wavelength modulation and short distances can be distinguished by power spectrum analysis. The distance measurement attains a relative standard deviation of around 10 −3 in the range from 1 mm to 23 mm, and a relative standard deviation of around 10 −4 is obtained in the velocity measurement. [ABSTRACT FROM AUTHOR]

We have proposed a novel double-layer microwave absorber based on spinel ferrite Ni 0.8 Co 0.2 Fe 2 O 4 nanofibers (NCFO NFs) and Ni-C hybrid NFs prepared via a facile electrospinning method combined with subsequent heat treatment. Electromagnetic and microwave absorption properties of the double-layer microwave absorbers, together with those of the single-layer ones, were systematically investigated in the frequency range of 2–18 GHz. The double-layer absorbers consisting of 50 wt% NCFO NFs/paraffin composite and 5 wt% Ni-C NFs/paraffin composite show superior microwave absorbing performance with stronger absorption and broader bandwidth as compared with the corresponding single-layer ones and many reported double-layer ones. As 1.5 mm thick NCFO NFs composite is used as the matching layer and 0.8 mm thick Ni-C NFs composite is employed as the absorption layer, the optimal reflection loss (RL) of the absorber reaches −84.9 dB at 17.0 GHz with an effective absorption bandwidth below −10 dB of 7.4 GHz ranging from 10.6 to 18 GHz. The enhancement of microwave absorption in the double-layer absorbers should be mainly ascribed to the improvement of impendence matching characteristics due to the efficient coupling and synergistic effect between two layers. These excellent properties demonstrate that our double-layer structures offer a new route to design microwave absorbers with lightweight and high absorption performance over a broad frequency range. [ABSTRACT FROM AUTHOR]

• The flexible FeCo@NFM was prepared by simple electrospinning method. • Small FeCo nanoparticles (∼10 nm) are uniformly encapsulated in the CNFs. • The as-prepared FeCo@NFM is directly used as a binder-free electrode. • The hierarchical structure can greatly promote Li+ insertion/extraction kinetics. • The electrode exhibits high capacity, good rate capability and cycling stability. The design of electrodes with excellent mechanical elasticity is the significant to developing flexible electronic devices with mechanical endurance and outstanding lithium storage properties. Herein, the flexible FeCo/carbon hybrid nanofiber membranes (named as FeCo@CNFM) were successfully prepared via electrospinning and subsequent carbonization process. From the macroscopic perspective, the FeCo@CNFM can bend at a large angle without any destruction, and be directly used as working electrode of lithium ions batteries (LIBs) without any expensive additives, demonstrating its extraordinary mechanical flexibility. From the microscopic perspective, the homogeneously dispersed fine FeCo nanoparticles and the three-dimensional (3D) interconnected transport network constructed of carbon nanofibers significantly shorten the lithium-ion transfer distance, eliminate the volume fluctuation during lithiation/delithiation process, enhance the utilization rate of active materials, and promote the electrical conductivity of the composite electrode, thus leading to remarkably improved electrochemical properties. As a consequence, the optimized FeCo@CNFM manifests a superior discharge capacity of 584.9 mA h g−1 at 100 mA g−1 after 100 cycles with long cycling stability and good rate capability of 227.1 mA h g−1 even at a large current rate of 2 A g−1, making it a promising flexible self-supporting anode for LIBs. [Display omitted] [ABSTRACT FROM AUTHOR]

Uniform Ba-doped LaFeO 3 nanofibers (NFs) with pure orthorhombic perovskite phase were successfully fabricated by electrospinning and subsequent calcination, and their ethanol sensing properties were investigated for the first time. The characterized results reveal that the well-crystallized La 1− x Ba x FeO 3 ( x  ≤ 0.3) NFs consist of a large amount of interconnected nanocrystals with the mean sizes of about 20–35 nm, and there are plenty of voids distributed between the nanoparticles within the NFs. Gas sensing investigations indicate that the sensors based on La 1− x Ba x FeO 3 NFs exhibit considerable sensitivity to ethanol gas and the response of sensors first increases and then decreases with the increase of Ba doping content. Among those sensor, the sensor based on La 0.75 Ba 0.25 FeO 3 NFs shows the best response. To 500 ppm of ethanol gas, the highest response for the La 0.75 Ba 0.25 FeO 3 NFs based sensor reaches 136.1 at a lower optimum operating temperature of 210 °C compared to the La 0.75 Ba 0.25 FeO 3 powder sensor, and the corresponding response and recovery times are about 42 and 40 s, respectively. Meanwhile, it shows good stability and selectivity to ethanol gas. Our results demonstrate that the as-prepared Ba-doped LaFeO 3 NFs can be a promising candidate for good performance ethanol sensors. [ABSTRACT FROM AUTHOR]

• A novel double-layer microwave absorber based on Co 2 Y@C NFs and CNFs was designed. • The minimum RL of − 63.7 dB and the maximum EAB of 10.2 GHz can be obtained. • The 1D core–shell structure provides a large amount of interfacial polarization. • The EM coupling and synergistic effect between Co 2 Y@C NFs and CNFs improve the impedance matching. A novel double-layer microwave absorber based on Ba 2 Co 2 Fe 12 O 22 @C core-shell nanofibers (Co 2 Y@C NFs) and carbon nanofibers (CNFs) was designed, and their microwave absorption properties were systematically investigated in the frequency range of 2–18 GHz. Benefiting from the better impedance matching characteristic of the matching layer (50 wt% Co 2 Y@C NFs/paraffin composite) and the stronger dielectric loss ability of the absorbing layer (5 wt% CNFs/paraffin composite), the optimized double-layer absorbers exhibit stronger absorption and wider effective absorption bandwidth compared to the corresponding single-layer absorbers. When the thicknesses of the absorbing and matching layer are respectively 0.62 mm and 1.38 mm (total thickness of 2 mm), the optimal reflection loss (RL) reaches −46.9 dB at 16.8 GHz, and the effective absorption bandwidth (EAB) is 4.1 GHz (from 13.9 to 18 GHz). Meanwhile, when the thicknesses of the absorbing and matching layer are 1.03 and 1.98 mm (total thickness of 3.01 mm), respectively, the optimal RL is up to −63.7 dB at 10.0 GHz with an EAB of 9.5 GHz ranging from 8.5 to 18 GHz. The absorption intensity and range of the double-layer absorber can be easily adjusted by regulating the thickness of the absorber, which shows good potential for practical applications. [ABSTRACT FROM AUTHOR]

Manufacturing lightweight, ultralow filler loading, broad bandwidth and highly efficient microwave absorbers is still a challenge. Herein, we have synthesized Co nanoparticles decorated N-self-doped carbon nanofibers (Co@NCNFs) composite by electrospinning followed by a two-step heat treatment and investigated its electromagnetic (EM) and microwave absorption performances under different filler contents (from 2.5 to 7.5 wt%) in paraffin wax matrix. It is found that the Co@NCNFs composite has strong ferromagnetism and moderate graphitization degree as well as abundant polar groups and defects, and Co nanoparticles encapsulated by graphitic carbon layers with sizes around 45–115 nm are uniformly dispersed in the NCNFs. With increasing the filler loading, the EM attenuation ability is gradually strengthened while the impedance matching level is just the opposite. The EM absorbing properties of the composites are more superior within 5.0 wt% Co@NCNFs loading owing to the synergy of improved impedance matching and satisfactory EM dissipation ability. Under an ultralow filler loading of 2.5 wt%, the optimal reflection loss (RL) can reach as strong as −49.3 dB at 17.83 GHz with a thin thickness of 1.61 mm and the maximum effective absorption bandwidth (EAB, RL<−10.0 dB) is as wide as 5.44 GHz (12.56–16.99 GHz) at 1.92 mm. When the filler loading is only 5.0 wt%, a minimum RL value of −52.3 dB is achieved at 6.36 GHz with the thickness of 3.03 mm and the maximum EAB is 4.64 GHz (13.36–18.00 GHz) at 1.42 mm. Compared to other Co/C composite absorbers, the as-prepared Co@NCNFs composite with well-designed constitute and structure demonstrates the better comprehensive absorption performance at a much lower filler loading. Therefore, the present Co@NCNFs may be more promising for practical applications as lightweight and high-performance EM wave absorbers especially in the medium and high frequency range. [Display omitted] • 1D Co@NCNFs were fabricated as lightweight and highly efficient microwave absorber. • The microwave absorption performance is more superior within 5 wt% filler loading. • The minimal reflection loss reaches −49.3 dB at ultralow filler content of 2.5 wt%. • A maximum effective absorption bandwidth of 5.44 GHz can be achieved. • Well-designed constitute and structure are responsible for the excellent property. [ABSTRACT FROM AUTHOR]

Background: The photo-thermal effect has been hypothesised to be one of the most possible biophysical mechanisms for laser-cochlea stimulation. However, there is a lack of studies to date for direct assessing laser heating in humans due to the large body of evidence required to demonstrate safety and efficacy. Instead, the majority focus on animals like the guinea pig, from which a number of valuable results have been gained. However, in light of the increasing need to improve laser safety, it has became necessary to find out whether studies on animals can shed light on safe laser parameters in the human cochlea. Hence, we conducted this contrastive analysis of laser heating between the human and guinea pig cochlea with the aim of assisting further investigations in this field.Methods: In this work, a 3D symmetrical model was adopted to simplify the spiraled cochlea. With attention focused on the effect of heat conduction, the time-dependent heat equation was solved using finite element method with the COMSOL Script. In the simulations, cochleae with different sizes and various boundary thermal conditions were utilized.Results: Laser heating in both cochleae has a similar trend. In the first stage, or at the beginning of the laser heating, both cochleae increased their temperatures rapidly. In the second stage in which the laser heating reached a quasi-steady stage, the peak temperatures began to rise slowly as more laser pulses were applied. However, three differences of the laser heating were observed. The first is regarding the temperature rise. The results show that laser heating in guinea pig is higher than that in human under the same laser parameters. The second difference is the fluctuation of temperature rise at the center of the modiolus. There is a larger fluctuation of temperature rise in the guinea pig cochlea, compared with that in the human cochlea. The third one is the time for reaching a steady thermal state. The results show that the guinea pig cochlea takes longer time to reach a steady thermal state than the human cochlea. Those differences are mainly attributed to the distinctive thermal boundaries and the various sizes of the two cochleae.Conclusions: This study finds that the laser heating in the guinea pig cochlea is higher than that in the human cochlea under the condition of the same laser parameters. However, laser stimulation still displays a high spatial selectivity in both cochleae despite the effects of heat conduction. The results indicate that experimental studies on the guinea pig could appropriately be an alternative model for the sake of laser safety. [ABSTRACT FROM AUTHOR]

Using the density functional theory combined with the nonequilibrium Green's function, the transport properties of double-walled carbon nanotubes (DWCNTs) and carbon boronitride (CBN) heteronanotubes were investigated. As the hopping length increases, the conductance of DWCNTs shows a dramatic variation that is independent of the intertube space. The transport of the CBN heterojunctions also displays abnormal behavior when the hopping length is changed, which is very different from the behavior of DWCNTs. The currents of the forward in the CBN heterojunctions are about 3–15 times as large as those of the back under lower bias voltages. The negative differential resistance (NDR) effect occurs in the CBN heterojunctions, and the peak-to-valley ratio in the additional NDR regions is about 2–4 for the current–voltage relationship. The hopping length and BN parts have a great influence on the transport of the double-walled nanodevices. [ABSTRACT FROM AUTHOR]

In this letter, we proposed and numerically analyzed an electric controlling polarization modulator of the terahertz wave, which is composed of a graphene monolayer microstructure with an L-shaped nanoholes array. The graphene microstructure is employed to excite the plasmonic dipolar and quadrupolar resonances in terahertz region. Through the superposition of the cross-polarized wave radiated by these plasmonic resonances, the polarization rotation effect can be obtained. Utilizing the capacitor doping, the rotation angle can be controlled by the external applied voltage, thus achieving a tunable polarization modulator. [ABSTRACT FROM AUTHOR]

In this paper, two emission “turn-on” chemosensors for Hg(II) sensing were designed and synthesized. Up-conversion NaYF 4 nanocrystals were prepared and used as the excitation host for both chemosensors. Spectral analysis suggested that there should be an efficient energy transfer between the host and the chemosensors, which was then confirmed by excited state lifetime analysis. Then two sensing systems using this up-conversion host and the two chemosensors were constructed, their sensing performance for Hg(II) ions was then studied. It was found that the probe emission intensity increased with increasing Hg(II) concentrations, showing an emission “turn-on” effect. Good selectivity and linear response were observed from both sensing systems. [ABSTRACT FROM AUTHOR]

In this paper, two europium complexes with large conjugation planes and proper triplet levels in their diamine ligands, Eu(DBM) 3 IPD and Eu 3 (DBM) 9 TBB, were synthesized and explored for oxygen sensing purpose, where DBM = 1,3-diphenyl-propane-1,3-dione, IPD = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline, TBB = 1,3,5-tris((2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl)methyl)benzene. It was anticipated that large conjugation planes and proper triplet levels could improve oxygen sensing performance by increasing collision probability with O 2 molecules. The two europium complexes were firstly characterized through single crystal analysis, UV–Vis absorption spectra, emission spectra and excited state lifetimes. Then, by doping them into a polymer matrix of poly(vinylpyrrolidone) with electrospinning technique, oxygen sensing parameters of the resulting composite fibers were studied and compared. Maximum sensitivity of 3.38 and short response time of 12 s were obtained. Linear Stern–Volmer plots were observed. [ABSTRACT FROM AUTHOR]

• Porous Ni nanofibers (Ni PNFs) were facilely fabricated by electrospinning. • Ni PNFs show greatly enhanced microwave absorption compared to Ni nanoparticles. • Enhanced dielectric loss and improved impedance matching are achieved. • An optimal reflection loss of −40.4 dB is obtained at a filler loading of 30 wt%. [Display omitted] One-dimensional Ni porous nanofibers (Ni PNFs) were prepared through a facile electrospinning followed by hydrogen reduction process, and their electromagnetic characteristics and microwave absorbing properties were investigated. Benefiting from the unique microstructure, three-dimensional conductive network and multiple attenuation forms, Ni PNFs exhibit remarkably increased dielectric loss capacity and improved impedance matching level relative to Ni nanoparticles. Consequently, Ni PNFs offer a significantly enhanced microwave absorption property with a minimum reflection loss (RL) of −40.4 dB at a relatively low filling ratio of 30 wt% and an effective absorption bandwidth (RL<−10 dB) of 4.6 GHz (8−12.6 GHz). Our results demonstrate that the microstructure and morphology of materials have considerable influence on their electromagnetic performances and the as-obtained Ni PNFs can be a promising candidate for lightweight and high-efficiency microwave absorption or electromagnetic shielding. [ABSTRACT FROM AUTHOR]

This work reports a flexible, self-supporting anode, as a novel electrode material to improve the energy density of lithium-ion batteries (LIBs). In this work, FeCo nanoparticles uniformly encapsulated in one-dimensional N-doped carbon nanofibers (denoted as FeCo@NCNFs) were synthesized by electrospinning and subsequent thermal treatment. The as-prepared FeCo@NCNFs films with high electrical conductivity and good flexibility can be directly used as LIBs anodes without the addition of any conductive agents and binders. The lithium storage performance of FeCo@NCNFs is far superior to that of pure NCNFs. The impact of the carbonization temperature on the structure and electrochemical properties of FeCo@NCNFs was also investigated. Results show that FeCo@NCNFs obtained at 600 °C exhibits the optimal electrochemical performance with a relatively high reversible capacity, i.e. , 566.5 mA h g−1 at 100 mA h g−1 after 100 cycles. The enhanced electrochemical properties can be mainly attributed to the synergy between 3D conductive NCNFs network and small FeCo nanoparticles, which can effectively improve the utilization rate of active materials, facilitate the transport of the electrons and lithium ions, and promote the charge-transport kinetics. Moreover, the homogeneous dispersion of FeCo nanoparticles in the NCNFs can also greatly buffer the volume change and improve the structural stability of the electrodes during the charge-discharge cycling. [Display omitted] • The flexible FeCo@NCNFs film was prepared by electrospinning method. • Ultrasmall FeCo nanoparticles (~ 10 nm) are uniformly encapsulated in the NCNFs. • The as-prepared FeCo@NCNFs film is directly used as a binder-free electrode. • The formation of three-dimensional conductive network can greatly promote Li+ insertion/extraction kinetics. • The electrode exhibits high capacity, good rate capability and cycling stability. [ABSTRACT FROM AUTHOR]

In establishing the numerical model to simulate the saturated soil-structure interaction subjected to dynamic loadings, the absorbing boundary conditions are usually applied to simulate the wave propagation in the field. In this study, a type of viscous boundary in conjunction with the domain reduction method (DRM) is proposed as an advanced absorbing boundary. The performance of this advanced absorbing boundary is examined by comparing the seismic responses of rectangular tunnel modeled with different boundary conditions in FLAC3D. The numerical results suggest that the advanced absorbing boundary has advantages over the other types of boundaries in minimizing the wave reflection at the numerical boundaries. Furthermore, the proposed advanced absorbing boundary is also employed for the seismic investigation of clay-pile systems, the results of which compare favorably well with the corresponding seismic centrifuge test results. The numerical analysis results indicate that the advanced absorbing boundary proposed in this study can be effectively employed for the efficient dynamic analysis of structures founded on the saturated porous media. • An effective absorbing boundary is proposed for the efficient dynamic numerical analysis of two-phase media. • Favorable performance of this new absorbing boundary is confirmed in comparison with conventional absorbing boundaries. • Validity of this new absorbing boundary is favorably examined by seismic centrifuge test results on clay-pile systems. [ABSTRACT FROM AUTHOR]

In order to ensure the safety of traffic, asphalt pavement is commonly required to utilize aggregates with excellent anti-abrasion property. This results in the lack of high-quality aggregates. The incorporation of solid waste in the aggregates is regarded as a high potential alternative for solving this problem. Since its material properties, such as rough surface, high Polished Stone Value (PSV) and the excellent adhesion property of asphalt, Basic Oxygen Furnace (BOF) slag can effectively improve the skid resistance of asphalt mixtures. First, the material properties of BOF slag are reviewed in this study. Then, the skid resistance of asphalt mixtures and aggregates are commendably evaluated by the Polished Stone Value test, Wehner/Schulze Tester, Aachen Polishing Machine, British Pendulum Test and Sand Patch test. The physical and mechanical properties of BOF slag play a key role in asphalt mixtures. This review found that the skid resistance mechanism of the BOF slag asphalt mixture is governed by factors such as BOF slag properties, incorporation methods and gradation types. Finally, the economic and environmental benefits of BOF slag asphalt mixtures were discussed. In addition, the function of gas catalysis and the melting of ice and snow can be added to the BOF slag asphalt mixture for a cleaner development in engineering. Furthermore, the existing problems, research directions and corresponding measures in this field are directed towards more durable and functional asphalt pavement construction. [ABSTRACT FROM AUTHOR]