Multiple exp-function method for soliton solutions ofnonlinear evolution equations
We applied the multiple exp-function scheme to the (2+1)-dimensional Sawada–Kotera (SK) equation and (3+1)-dimensional nonlinear evolution equation and analytic particular solutions have been deduced. The analytic particular solutions contain one-soliton, two-soliton, and three-soliton type solutions. With the assistance of Maple, we demonstrated the efficiency and advantages of the procedure that generalizes Hirota's perturbation scheme. The obtained solutions can be used as a benchmark for numerical solutions and describe the physical phenomena behind the model.
A new two-mode thermo-and squeezing-mixed optical field
Thermal entanglement of the spin-1 Ising–Heisenberg diamond chain with biquadratic interaction
Tracking consensus for nonlinear heterogeneous multi-agent systems subject to unknown disturbances via sliding mode control
Collective transport of Lennard–Jones particles through one-dimensional periodic potentials
The surrounding media in which transport occurs contains various kinds of fields, such as particle potentials and external potentials. One of the important questions is how elements work and how position and momentum are redistributed in the diffusion under these conditions. For enriching Fick's law, ordinary non-equilibrium statistical physics can be used to understand the complex process. This study attempts to discuss particle transport in the one-dimensional channel under external potential fields. Two kinds of potentials–-the potential well and barrier–-which do not change the potential in total, are built during the diffusion process. There are quite distinct phenomena because of the different one-dimensional periodic potentials. By the combination of a Monte Carlo method and molecular dynamics, we meticulously explore why an external potential field impacts transport by the subsection and statistical method. Besides, one piece of evidence of the Maxwell velocity distribution is confirmed under the assumption of local equilibrium. The simple model is based on the key concept that relates the flux to sectional statistics of position and momentum and could be referenced in similar transport problems.
Asymmetrical plasmon reflections in tapered graphene ribbons with wrinkle edges Hot!
Asymmetrical graphene plasmon reflection patterns are found in infrared near-field images of tapered graphene ribbons epitaxially grown on silicon carbon substrates. Comparing experimental data with numerical simulations, the asymmetry of these patterns is attributed to reflection of plasmons by wrinkled edges naturally grown in the graphene. These graphene wrinkles are additional plasmon reflectors with varying optical conductivity, which act as nanometer scale plasmonic modulators and thus have potential applications in photoelectric information detectors, transmitters, and modulators.
Molecular dynamics simulation of decomposition and thermal conductivity of methane hydrate in porous media
The hydrate has characteristics of low thermal conductivity and temperature sensitivity. To further analysis the mechanism of thermal conductivity and provide method for the exploitation, transportation and utilization of hydrate, the effect of decomposition and thermal conductivity of methane hydrate in porous media has been studied by using the molecular dynamics simulation. In this study, the simulation is carried out under the condition of temperature 253.15 K–273.15 K and pressure 1 MPa. The results show that the thermal conductivity of methane hydrate increases with the increase of temperature and has a faster growth near freezing. With the addition of porous media, the thermal conductivity of the methane hydrate improves significantly. The methane hydrate-porous media system also has the characteristics of vitreous body. With the decrease of the pore size of the porous media, thermal conductivity of the system increases gradually at the same temperature. It can be ascertained that the porous media of different pore sizes have strengthened the role of the thermal conductivity of hydrates.
Electronic transport properties of lead nanowires
Restraint of spatial distribution in high-order harmonic generation from a model of hydrogen molecular ion
The spatial distribution in high-order harmonic generation (HHG) is theoretically investigated by using a few-cycle laser pulse from a two-dimensional model of a hydrogen molecular ion. The spatial distribution in HHG demonstrates that the harmonic spectra are sensitive to the carrier envelope phase and the duration of the laser pulse. The HHG can be restrained by a pulse with the duration of 5 fs in the region from the 90th to 320th order. This characteristic is illustrated by the probability density of electron wave packet distribution. The electron is mainly located near the nucleus along the positive-x direction from 3.0 o.c. to 3.2 o.c., which is an important time to generate the HHG in the plateau area. We also demonstrate the time–frequency distribution in the region of the positive-and negative-x direction to explain the physical mechanism.
Pressure-broadened atomic Li(2s-2p) line perturbed by ground neon atoms in the spectral wings and core
Full quantum calculations are performed to investigate the broadening profiles of the atomic lithium Li(2s-2p) resonance line induced by interactions with ground Ne(2s22p6) perturbers in the spectral wings and core. The X2Σ+, A2Π, and B2Σ+ potential-energy curves of the two first low lying LiNe molecular states, as well as the corresponding transition dipole moments, are determined with ab initio methods based on the SA-CASSCF-MRCI calculations. The emission and absorption coefficients in the wavelength range 550–800 nm and the line-core width and shift are investigated theoretically for temperatures ranging from 130 K to 3000 K. Their temperature dependence is analyzed, and the obtained results are compared with the previous experimental measurements and theoretical works.
Asymmetrical mirror optimization for a 140 GHz TE22, 6 quasi-optical mode converter system
Laser beam shaping with magnetic fluid-based liquid deformable mirrors
Simple and universal method in designs of high-efficiency diffractive optical elements for spectrum separation and beam concentration
Diffractive optical elements (DOEs) with spectrum separation and beam concentration (SSBC) functions have important applications in solar cell systems. With the SSBC DOEs, the sunlight radiation is divided into several wave bands so as to be effectively absorbed by photovoltaic materials with different band gaps. A new method is proposed for designing high-efficiency SSBC DOEs, which is physically simple, numerically fast, and universally applicable. The SSBC DOEs are designed by the new design method, and their performances are analyzed by the Fresnel diffraction integral method. The new design method takes two advantages over the previous design method. Firstly, the optical focusing efficiency is heightened by up to 10%. Secondly, focal positions of all the designed wavelengths can be designated arbitrarily and independently. It is believed that the designed SSBC DOEs should have practical applications to solar cell systems.
Analytical solutions for a doubly driven two-level atom
High quality electromagnetically induced transparency spectroscopy of 87Rb in a buffer gas cell with a magnetic field
We have studied the phenomenon of electromagnetically induced transparency (EIT) of 87Rb vapor with a buffer gas in a magnetic field at room temperature. It is found that the spectral lines caused by the velocity selective optical pump effects get much weaker and wider when the sample cell is mixed with a 5-Torr N2 gas while the EIT signal is kept almost unchanged. A weighted least-square fit is also developed to remove the Doppler broadening completely. This spectral method provides a way to measure the Zeeman splitting with high resolution, for example, the Λ -type EIT resonance splits into four peaks on the D2 line of 87Rb in the thermal 2-cm vapor cell with a magnetic field along the electric field of the linearly polarized coupling laser. The high-resolution spectrum can be used to lock the laser to a given frequency by tuning the magnetic field.
Quantum feedback cooling of two trapped ions
We present a sub-Doppler cooling scheme of a two-trapped-ion crystal by quantum feedback control method. In the scheme, we obtain the motional information by continuously measuring the spontaneous emission photons from one single ion of the crystal, and then apply a feedback force to cool the whole chain down.We derive the cooling dynamics of the cooling scheme using quantum feedback theory and quantum regression theorem. The result shows that with experimentally achievable parameters, our scheme can achieve lower temperature and faster cooling rate than Doppler cooling.
Quantum interference between heralded single photon stateand coherent state
Controllable double electromagnetically induced transparency in a closed four-level-loop cavity–atom system
Spectral dynamical behavior in two-section, quantum well, mode-locked laser at 1.064μm
Stable single-mode operation of 894.6 nm VCSEL at high temperatures for Cs atomic sensing
In this paper, stable single-mode operation at high temperatures is produced by the surface-relief-integrated vertical cavity surface emitting laser (VCSEL). The gain-cavity mode detuning technique is employed to realize high operating temperatures for the VCSEL. The surface relief is etched in the centre of the top side as a mode discriminator for the fundamental mode output, and the threshold current minimum is 1.94 mA at high temperatures by the gain-cavity mode detuning technique. Maximum single-fundamental-mode output power of 0.45 mW at 80℃ is obtained, and the side mode suppression ratios (SMSRs) are more than 30 dB with increasing temperature and current, respectively.
Supercontinuum generation in seven-core photonic crystal fiber pumped by a broadband picosecond pulsed fiber amplifier
Design and performance of a composite Tm: YAG laser pumped by VBG-stabilized narrow-band laser diode
Observation of stable bound soliton with dual-wavelength in a passively mode-locked Er-doped fiber laser
Intense supercontinuum generation in the near-ultraviolet range from a 400-nm femtosecond laser filament array in fused silica
An intense supercontinuum (SC) in the near-ultraviolet range is generated from filamentation by focusing a 400-nm laser into fused silica with a microlens array (MLA). The spectrum of the SC is shown to be sensitive to the distance between the MLA and fused silica. In our optimal conditions, the near-ultraviolet SC can cover a range of 350–600 nm, where a bandwidth of approximately 55 nm above the 1μ J/nm spectral energy density and 20 nm bandwidth with tens ofμJ/nm are achieved. In addition, the energy conversion efficiency of the 400 nm laser for SC generation is further analyzed. A maximum conversion efficiency of 66% is obtained when the entrance face of fused silica is set around the focus of the MLA.
Characterization of the pairwise correlations in different quantum networks consisting of four-wave mixers and beamsplitters
We investigate the performances of the pairwise correlations (PCs) in different quantum networks consisting of four-wave mixers (FWMs) and beamsplitters (BSs). PCs with quantum correlation in different quantum networks can be verified by calculating the degree of relative intensity squeezing for any pair of all the output fields. More interestingly, the quantum correlation recovery and enhancement are present in the FWM+BS network and the repulsion effect phenomena (signal (idler)–frequency mode cannot be quantum correlated with the other two idler (signal)–frequency modes simultaneously) between the PCs with quantum correlation are predicted in the FWM+FWM and FWM+FWM+FWM networks. Our results presented here pave the way for the manipulation of the quantum correlation in quantum networks.
Theoretical study of the odd–even-order harmonic generation for asymmetric ions in non-Born–Oppenheimer approximation
Spatiotemporal evolution of continuous-wave field and dark soliton formation in a microcavity with normal dispersion
Spectroscopic and radiation-resistant properties of Er, Pr: GYSGG laser crystal operated at 2.79μm
Bifurcated overtones of one-way localized Fabry–Pérot resonances in parity-time symmetric optical lattices
Since the first observation of parity-time (PT) symmetry in optics, varied interesting phenomena have been discovered in both theories and experiments, such as PT phase transition and unidirectional invisibility, which turns PT-symmetric optics into a hotspot in research. Here, we report on the one-way localized Fabry–Pérot (FP) resonance, where a well-designed PT optical resonator may operate at exceptional points with bidirectional transparency but unidirectional field localization. Overtones of such one-way localized FP resonance can be classified into a blue shifted branch and a red shifted branch. Therefore, the fundamental resonant frequency is not the lowest one. We find that the spatial field distributions of the overtones at the same absolute order are almost the same, even though their frequencies are quite different.
Mechanically tunable metamaterials terahertz dual-band bandstop filter
Low power consumption 4-channel variable optical attenuator array based on planar lightwave circuit technique
The power consumption of a variable optical attenuator (VOA) array based on a silica planar lightwave circuit was investigated. The thermal field profile of the device was optimized using the finite-element analysis. The simulation results showed that the power consumption reduces as the depth of the heat-insulating grooves is deeper, the up-cladding is thinner, the down-cladding is thicker, and the width of the cladding ridge is narrower. The materials component and thickness of the electrodes were also optimized to guarantee the driving voltage under 5 V. The power consumption was successfully reduced to as low as 155 mW at an attenuation of 30 dB in the experiment.
A tunable XUV monochromatic light source based on the time preserving grating selection of high-order harmonic generation
Bubble acoustical scattering cross section under multi-frequency acoustic excitation
The acoustical scattering cross section is usually employed to evaluate the scattering ability of the bubbles when they are excited by the incident acoustic waves. This parameter is strongly related to many important applications of performance prediction for search sonar or underwater telemetry, acoustical oceanography, acoustic cavitation, volcanology, and medical and industrial ultrasound. In the present paper, both the analytical and numerical analysis results of the acoustical scattering cross section of a single bubble under multi-frequency excitation are obtained. The nonlinear characteristics (e.g., harmonics, subharmonics, and ultraharmonics) of the scattering cross section curve under multi-frequency excitation are investigated compared with single-frequency excitation. The influence of several paramount parameters (e.g., bubble equilibrium radius, acoustic pressure amplitude, and acoustic frequencies) in the multi-frequency system on the predictions of scattering cross section is discussed. It is shown that the combination resonances become significant in the multi-frequency system when the acoustic power is big enough, and the acoustical scattering cross section is promoted significantly within a much broader range of bubble sizes and acoustic frequencies due to the generation of more resonances.
Acoustic-electromagnetic slow waves in a periodical defective piezoelectric slab
Coupled slow waves, slow acoustic waves, and electromagnetic waves are simultaneously achieved based on a piezoelectric material, in which a line defect is created within a honeycomb lattice array of cylindrical holes etched in a LiNbO3 slab. Finite element simulations in frequency domain and time domain demonstrate that a highly localized slow mode is obtained in the defect. Owing to the piezoelectricity of LiNbO3, acoustic and electromagnetic waves are coupled with each other and transmit along the line defect. Therefore, in addition to a slow acoustic wave, an electromagnetic wave with a group velocity even lower than conventional acoustic waves is achieved.
Relationship between the real contact area and contact force in pre-sliding regime
Buckling analysis of nanobeams with exponentially varying stiffness by differential quadrature method
Experimental study and theoretical analysis of fluid resistance in porous media of glass spheres
Radiative properties of matter based on quantum statistical method
We present the preliminary results of our code OPAQS (opacity calculation using quantum statistical model) that is based on the self consistent Hartree–Fock–Slater model for the average atom. The code is capable of performing robust calculations of average charge state, frequency-dependent and mean opacities. The accuracy of the atomic model is verified by comparing the calculations of average charge state with various published results. The monochromatic opacities for iron computed at different sets of temperatures and densities are compared with LEDCOP. The Rosseland and Planck opacities for iron and aluminum are validated with some state-of-the-art codes. The results are in good agreement with the published data.
Magneto-Rayleigh–Taylor instability in compressible Z-pinch liner plasmas
Influence of a centered dielectric tube on inductively coupled plasma source: Chamber structures and plasma characteristics
Numerical simulation of the initial plasma formation and current transfer in single-wire electrical explosion in vacuum
Atomic pair distribution function method development at the Shanghai Synchrotron Radiation Facility
The atomic pair distribution function (PDF) reveals the interatomic distance in a material directly in real-space. It is a very powerful method to characterize the local structure of materials. With the help of the third generation synchrotron facility and spallation neutron source worldwide, the PDF method has developed quickly both experimentally and theoretically in recent years. Recently this method was successfully implemented at the Shanghai Synchrotron Radiation Facility (SSRF). The data quality is very high and this ensures the applicability of the method to study the subtle structural changes in complex materials. In this article, we introduce in detail this new method and show some experimental data we collected.
Laser-induced fabrication of highly branched CuS nanocrystals with excellent near-infrared absorption properties
Crystal structures and electronic properties of solid fluorine under high pressure
As the previously proposed structures of C2/m and C2/c possess similar enthalpies and x-ray diffraction patterns, the space group of fluorine at ambient pressure is in controversy. We successfully obtain its thermodynamically stable low-pressure phase, which shares the same structure as the earlier known C2/c. Further investigations on phonon spectra reveal the instability of the C2/m structure with imaginary frequency in the Brillouin zone and confirm the dynamically stable property of the C2/c structure at the same time. Compressing fluorine up to 8 GPa, the C2/c phase is found to undergo a phase transition to a new structure with a space group of Cmca. Electronic energy band structures indicate the insulating feature of C2/c and Cmca with no bands across the Fermi level. The infrared (IR) and Raman spectra of C2/c and Cmca at selected pressures are calculated to provide useful information to future experiments.
Optical waveguide in Nd: Bi12SiO20 crystal produced bymulti-energy C ion implantation
Molecular dynamics simulations of cascade damage near the Y2Ti2O7 nanocluster/ferrite interface in nanostructured ferritic alloys
A comparative study of cascades in nanostructured ferritic alloys and pure Fe is performed to reveal the influence of Y2Ti2O7 nanocluster on cascades by molecular dynamics simulations. The cascades with energies of primary knock-on atom (PKA) ranging from 0.5 keV to 4.0 keV and PKA's distances to the interface from 0 Å to 50 Å are simulated. It turns out that the Y2Ti2O7 nanocluster can absorb the kinetic energy of cascade atoms, prevent the cascade from extending and reduce the defect production significantly when the cascades overlap with the nanocluster. When the cascade affects seriously the nanocluster, the weak sub-cascade collisions are rebounded by the nanocluster and thus leave more interstitials in the matrix. On the contrary, when the cascade contacts weakly the nanocluster, the interface can pin the arrived interstitials and this leaves more vacancies in the matrix. Moreover, the results indicate that the Y2Ti2O7 nanocluster keeps stable upon the displacement cascade damage.
First-principles study of the new potential photovoltaic absorber: Cu2MgSnS4 compound
Effects of the Be22W phase formation on hydrogen retention and blistering in mixed Be/W systems
We have performed first-principles density functional theory calculations to investigate the retention and migration of hydrogen in Be22W, a stable low-W intermetallic compound. The solution energy of interstitial H in Be22W is found to be 0.49 eV lower, while the diffusion barrier, on the other hand, is higher by 0.13 eV compared to those in pure hcp-Be. The higher solubility and lower diffusivity for H atoms make Be22W a potential beneficial secondary phase in hcp-Be to impede the accumulation of H atoms, and hence better resist H blistering. We also find that in Be22W, the attraction between an interstitial H and a beryllium vacancy ranges from 0.34 eV to 1.08 eV, which indicates a weaker trapping for hydrogen than in pure Be. Our calculated results suggest that small size Be22W particles in hcp-Be might serve as the hydrogen trapping centers, hinder hydrogen bubble growth, and improve the resistance to irradiation void swelling, just as dispersed oxide particles in steel do.
Electronic structure & yield strength prediction for dislocation–Mo complex in the γ phase of nickel-based superalloys
Molybenum's effects when added in the γ phase of nickel-based superalloys were studied using the lattice Green's function multiscale method. The electronic structure of the dislocation–Mo complex was analyzed and hybridization was found to contribute to the strengthening. Moreover, by combining the interaction energies calculated from two scales, the yield stress was theoretically predicted at 0 K and finite temperature.
Physical implications of activation energy derived from temperature dependent photoluminescence of InGaN-based materials
Physical implications of the activation energy derived from temperature dependent photoluminescence (PL) of InGaN-based materials are investigated, finding that the activation energy is determined by the thermal decay processes involved. If the carrier escaping from localization states is responsible for the thermal quenching of PL intensity, as often occurs in InGaN materials, the activation energy is related to the energy barrier height of localization states. An alternative possibility for the thermal decay of the PL intensity is the activation of nonradiative recombination processes, in which case thermal activation energy would be determined by the carrier capture process of the nonradiative recombination centers rather than by the ionization energy of the defects themselves.
Coherent charge transport in ferromagnet/semiconductor nanowire/ferromagnet double barrier junctions with the interplay of Rashba spin–orbit coupling, induced superconducting pair potential, and external magnetic field
By solving the Bogoliubov–de Gennes equation, the influence of the interplay of Rashba spin–orbit coupling, induced superconducting pair potential, and external magnetic field on the spin-polarized coherent charge transport in ferromagnet/semiconductor nanowire/ferromagnet double barrier junctions is investigated based on the Blonder–Tinkham–Klapwijk theory. The coherence effect is characterized by the strong oscillations of the charge conductance as a function of the bias voltage or the thickness of the semiconductor nanowire, resulting from the quantum interference of incoming and outgoing quasiparticles in the nanowire. Such oscillations can be effectively modulated by varying the strength of the Rashba spin–orbit coupling, the thickness of the nanowire, or the strength of the external magnetic field. It is also shown that two different types of zero-bias conductance peaks may occur under some particular conditions, which have some different characteristics and may be due to different mechanisms.
Phase diagram of a family of one-dimensional nearest-neighbor tight-binding models with an exact mobility edge
Recently, an interesting family of quasiperiodic models with exact mobility edges (MEs) has been proposed (Phys. Rev. Lett. 114 146601 (2015)). It is self-dual under a generalized duality transformation. However, such transformation is not obvious to map extended (localized) states in the real space to localized (extended) ones in the Fourier space. Therefore, it needs more convictive evidences to confirm the existence of MEs. We use the second moment of wave functions, Shannon information entropies, and Lypanunov exponents to characterize the localization properties of the eigenstates, respectively. Furthermore, we obtain the phase diagram of the model. Our numerical results support the existing analytical findings.
Plasmonic Mach–Zehnder interferometric sensor based on a metal–insulator–metal nanostructure
Abundant photoelectronic behaviors of La0.67Sr0.33MnO3/Nb: SrTiO3 junctions
Temperature dependence on rectifying and photoelectronic properties of La0.67Sr0.33MnO3/Nb:SrTiO3 (LSMO/STON) junctions with the thickness values of LSMO film varying from 1 nm to 54 nm are systematically studied. As shown experimentally, the junctions exhibit good rectifying properties. The significant differences in photoemission property among the LSMO/STON junctions are observed. For the junction in a thicker LSMO film, the photocurrent shows a monotonic growth when temperature decreases from 300 K to 13 K. While for the junction in an ultrathin LSMO film, the behaviors of photocurrent are more complicated. The photocurrent increases rapidly to a maximum and then smoothly decreases with the decrease of temperature. The unusual phenomenon can be elucidated by the diffusion and recombination model of the photocarrier.
Analytical capacitance model for 14 nm FinFET considering dual-k spacer
High holding voltage SCR for robust electrostatic discharge protection
A novel silicon controlled rectifier (SCR) with high holding voltage (Vh) for electrostatic discharge (ESD) protection is proposed and investigated in this paper. The proposed SCR obtains high Vh by adding a long N+ layer (LN+) and a long P+ layer (LP+), which divide the conventional low voltage trigger silicon controlled rectifier (LVTSCR) into two SCRs (SCR1:P+/Nwell/Pwell/N+ and SCR2:P+/LN+/LP+/N+) with a shared emitter. Under the low ESD current (IESD), the two SCRs are turned on at the same time to induce the first snapback with high Vh (Vh1). As the IESD increases, the SCR2 will be turned off because of its low current gain. Therefore, the IESD will flow through the longer SCR1 path, bypassing SCR2, which induces the second snapback with high Vh (Vh2). The anti-latch-up ability of the proposed SCR for ESD protection is proved by a dynamic TLP-like (Transmission Line Pulse-like) simulation. An optimized Vh2 of 7.4 V with a maximum failure current (It2) of 14.7 mA/μ m is obtained by the simulation.
Electronic structure of heavy fermion system CePt2In7 from angle-resolved photoemission spectroscopy
We have carried out high-resolution angle-resolved photoemission measurements on the Ce-based heavy fermion compound CePt2In7 that exhibits stronger two-dimensional character than the prototypical heavy fermion system CeCoIn5. Multiple Fermi surface sheets and a complex band structure are clearly resolved. We have also performed detailed band structure calculations on CePt2In7. The good agreement found between our measurements and the calculations suggests that the band renormalization effect is rather weak in CePt2In7. A comparison of the common features of the electronic structure of CePt2In7 and CeCoIn5 indicates that CeCoIn5 shows a much stronger band renormalization effect than CePt2In7. These results provide new information for understanding the heavy fermion behaviors and unconventional superconductivity in Ce-based heavy fermion systems.
Electronic structure and nematic phase transition in superconducting multiple-layer FeSe films grown by pulsed laser deposition method Hot!
We report comprehensive angle-resolved photoemission investigations on the electronic structure of single crystal multiple-layer FeSe films grown on CaF2 substrate by pulsed laser deposition (PLD) method. Measurements on FeSe/CaF2 samples with different superconducting transition temperatures Tc of 4 K, 9 K, and 14 K reveal electronic difference in their Fermi surface and band structure. Indication of the nematic phase transition is observed from temperature-dependent measurements of these samples; the nematic transition temperature is 140–160 K, much higher than~90 K for the bulk FeSe. Potassium deposition is applied onto the surface of these samples; the nematic phase is suppressed by potassium deposition which introduces electrons to these FeSe films and causes a pronounced electronic structure change. We compared and discussed the electronic structure and superconductivity of the FeSe/CaF2 films by PLD method with the FeSe/SrTiO3 films by molecular beam epitaxy (MBE) method and bulk FeSe. The PLD-grown multilayer FeSe/CaF2 is more hole-doped than that in MBE-grown multiple-layer FeSe films. Our results on FeSe/CaF2 films by PLD method establish a link between bulk FeSe single crystal and FeSe/SrTiO3 films by MBE method, and provide important information to understand superconductivity in FeSe-related systems.
Magnetic properties of Sn-substituted Ni–Zn ferrites synthesized from nano-sized powders of NiO, ZnO, Fe2O3, and SnO2
Modified magnetomechancial model in the constant and low intensity magnetic field based on J–A theory
Electrical analysis of inter-growth structured Bi4Ti3O12–Na0.5Bi4.5Ti4O15 ceramics
Accuracy design of ultra-low residual reflection coatingsfor laser optics
Enhancing redshift phenomenon in time-resolved photoluminescence spectra of AlGaN epilayer
AlGaN epitaxial layer has been studied by means of temperature-dependent time-integrated photoluminescence (PL) and time-resolved photoluminescence (TRPL). An enhancing redshift phenomenon in TRPL spectra with increasing temperature was observed, and the localized excitons behaved like quasi two-dimensional excitons between 6 K and 90 K. We demonstrated that these behaviors are caused by a change in the carrier dynamics with increasing temperature due to the competition of carriers' localization and delocalization in the AlGaN alloy.
Profile function properties & optical transition formulae
Guided mode resonance in planar metamaterials consistingof two ring resonators with different sizes
Electromechanical actuation of CNT/PVDF composite films based on a bridge configuration
Bridged strips consisting of carbon nanotubes and poly(vinylidene fluoride) are developed, which exhibit notable deflection in response to very low driven voltages (< 1 V), because of both the excellent conductivity of the unique carbon nanotube film and the powerful thermal expansion capability of the polymer. The actuators demonstrate periodic vibrations motivated by the alternating signals. The amplitude of displacement is dependent not only on the driven voltage but also on the applied frequency. The mechanism of actuation is confirmed to be the thermal power induced by the electrical heating. By accelerating the dissipation of heat, the vibration response at higher frequencies can be significantly enhanced. The useful locomotion shows great promise in potential applications such as miniature smart devices and micro power generators.
Growth and characterization of AlN epilayers using pulsed metal organic chemical vapor deposition
Low-temperature-cured highly conductive composite of Ag nanowires & polyvinyl alcohol
Conductivity and applications of Li-biphenyl-1, 2-dimethoxyethane solution for lithium ion batteries
The total conductivity of Li-biphenyl-1,2-dimethoxyethane solution (LixBp(DME)9.65, Bp=biphenyl, DME=1,2-dimethoxyethane, x=0.25, 0.50, 1.00, 1.50, 2.00) is measured by impedance spectroscopy at a temperature range from 0℃ to 40℃. The Li1.50Bp(DME)9.65 has the highest total conductivity 10.7 mS/cm. The conductivity obeys Arrhenius law with the activation energy (Ea(x=0.50)=0.014 eV, Ea(x=1.00)=0.046 eV). The ionic conductivity and electronic conductivity of LixBp(DME)9.65 solutions are investigated at 20℃ using the isothermal transient ionic current (ITIC) technique with an ion-blocking stainless steal electrode. The ionic conductivity and electronic conductivity of Li1.00Bp(DME)9.65 are measured as 4.5 mS/cm and 6.6 mS/cm, respectively. The Li1.00Bp(DME)9.65 solution is tested as an anode material of half liquid lithium ion battery due to the coexistence of electronic conductivity and ionic conductivity. The lithium iron phosphate (LFP) and Li1.5Al0.5Ti1.5(PO4)3 (LATP) are chosen to be the counter electrode and electrolyte, respectively. The assembled cell is cycled in the voltage range of 2.2 V–3.75 V at a current density of 50 mA/g. The potential of Li1.00Bp(DME)9.65 solution is about 0.3 V vs. Li+/Li, which indicates the solution has a strong reducibility. The Li1.00Bp(DME)9.65 solution is also used to prelithiate the anode material with low first efficiency, such as hard carbon, soft carbon and silicon.
Negative-index dispersion and accidental mode degeneracy inan asymmetric spoof–insulator–spoof waveguide
Bridge-free fabrication process for Al/AlOx/Al Josephson junctions
We fabricate different-sized Al/AlOx/Al Josephson junctions by using a simple bridge-free technique, in which only single-layer E-beam resist polymethyl methacrylate (PMMA) is exposed at low accelerate voltage (below 30 kV) and the size of junction can be varied in a large range. Compared with the bridge technique, this fabrication process is very robust because it can avoid collapsing the bridge during fabrication. This makes the bridge-free technique more popular to meet different requirements for Josephson junction devices especially for superconducting quantum bits.
Double-gate-all-around tunnel field-effect transistor
In this work, a double-gate-all-around tunneling field-effect transistor is proposed. The performance of the novel device is studied by numerical simulation. The results show that with a thinner body and an additional core gate, the novel device achieves a steeper subthreshold slope, less susceptibility to the short channel effect, higher on-state current, and larger on/off current ratio than the traditional gate-all-around tunneling field-effect transistor. The excellent performance makes the proposed structure more attractive to further dimension scaling.
Evaluation of current and temperature effects on optical performance of InGaAlP thin-film SMD LED mounted on different substrate packages
Image reconstruction for cone-beam computed tomography using total p-variation plus Kullback–Leibler data divergence
Detection of invisible phonon modes in individual defect-free carbon nanotubes by gradient-field Raman scattering
We provide an effective method to investigate the field gradient effect in nanoconfined plasmon–matter interaction. Aligned ultralong SWNTs without defects were grown on marked substrates, followed by assembling gold nanoparticle clusters around individual nanotubes. The Raman scattering behavior of a nanotube placed in an atomic scale nanogap between adjacent nanoparticles was studied. In addition to the expected plasmon-induced Raman enhancement up to 103, the defect-free D-mode of an individual SWNT induced by gradient field is found for the first time. When the light is confined at atomic scale, gradient field Raman scattering becomes significant and dipole-forbidden phonon modes can be activated by quadrupole Raman tensor variation, indicating breakdown of the Raman selection rules.
Feedback arcs and node hierarchy in directed networks Hot!
Directed networks such as gene regulation networks and neural networks are connected by arcs (directed links). The nodes in a directed network are often strongly interwound by a huge number of directed cycles, which leads to complex information-processing dynamics in the network and makes it highly challenging to infer the intrinsic direction of information flow. In this theoretical paper, based on the principle of minimum-feedback, we explore the node hierarchy of directed networks and distinguish feedforward and feedback arcs. Nearly optimal node hierarchy solutions, which minimize the number of feedback arcs from lower-level nodes to higher-level nodes, are constructed by belief-propagation and simulated-annealing methods. For real-world networks, we quantify the extent of feedback scarcity by comparison with the ensemble of direction-randomized networks and identify the most important feedback arcs. Our methods are also useful for visualizing directed networks.
Density functional theory investigation of carbon monoxide adsorption on the kaolinite (001) surface