Modern Physics Letters B

In this paper, we theoretically study the ballistic transport through a weakly open circular mesostructure within the framework of pseudopath semiclassical approximation. By defining the interference factor and comparing it numerically with the transmission amplitude, we demonstrate that the fluctuations in transmission amplitude are mainly due to the interference effects between different classical trajectories. In addition, we calculate the Fano factor versus cutoff length of classical trajectories in the energy domain to illustrate that the fluctuations in transmission amplitude mainly arise from the contribution of short-length classical trajectories. We further show that the transmission length power spectra not only associate with a lot of classical trajectories but with a series of nonclassical trajectories due to the diffraction scattering effects. Moreover, we show that the classical trajectories distributed in the mode–mode coupling function give the largest contribution to the corresponding transmission amplitude. We hope that our results and analysis can be used to reveal new effects of mesoscopic systems and to provide theoretical basis for the design of mesoscopic devices.

Power shortage is the bottleneck for the wide application of gastrointestinal (GI) robot. Owing to the limited volume and free change of orientation of the receiving set in GI trace, the optimal of receiving set is the key point to promote the transmission efficiency of wireless power transmission system. A new type of receiving set, similar to the winding of three-phase asynchronous motor, is presented and compared with the original three-dimensional orthogonal coil. Considering the given volume and the space utilization ratio, the three-phase and the three-orthogonal ones are the parameters which are optimized and compared. Both the transmission efficiency and stability are analyzed and verified by in vitro experiments. Animal experiments show that the new one could provide at least 420 mW power in volume of $\mathrm{\Phi }11\times 13\mathrm{\text{mm}}$ with a uniformity of 78.3% for the GI robot.

A new needle-to-droplet electrode structure with a micro discharge gap (2 mm) was designed to achieve direct current (DC) discharge plasma in ambient air with the aim of using the plasma to sterilize liquids. Without using noble gases or an external air flow, we succeeded in generating both a negative and positive DC plasma at atmospheric pressure. The plasma was driven by a 0 to −20,000 V, 100 W DC power supply. A stainless steel needle with a tip diameter of $\sim 50\mu \mathrm{\text{m}}$ and a 200-$\mu \mathrm{\text{L}}$ droplet of bacteria-containing liquid served as the electrodes. At atmospheric pressure and room temperature (23${}^{\circ }$C), utilizing the negative DC plasma, the discharge time lasted 10 s; the results showed that the higher the discharge voltage, the more efficient the sterilization effect. Conversely, when we applied a voltage of −5.5 kV, we found that the sterilization effect was more efficient for longer discharge times. Our findings demonstrate that Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) can be killed in about 30 s. Our experiments show that our sterilization method required less time and was more efficient for positive than for negative DC plasma under the same conditions.

Stability of Ag₂S@ZnS QDs in water is a crucial concern for their application in biology. In this work, both physical sustainability and emission stability of Ag₂S QDs were enhanced using parameter optimization of a pulsed microwave irradiation (MI) method up to 105 days after their preparation. UV–Vis and photoluminescence spectroscopies depicted an absorption and emission about 817 nm and 878 nm, respectively. X-ray diffraction (XRD) analysis showed a growth of Ag₂S acanthite phase. Transmission Electron Microscopy (TEM) images revealed a clear formation of Ag₂S@ZnS core–shell structure.

Rational solutions and hybrid solutions from N-solitons are obtained by using the bilinear method and a long wave limit method. Line rogue waves and lumps in the (2+1)-dimensional nonlinear Schrödinger (NLS) equation are derived from two-solitons. Then from three-solitons, hybrid solutions between kink soliton with breathers, periodic line waves and lumps are derived. Interestingly, after the collision, the breathers are kept invariant, but the amplitudes of the periodic line waves and lumps change greatly. For the four-solitons, the solutions describe as breathers with breathers, line rogue waves or lumps. After the collision, breathers and lumps are kept invariant, but the line rogue wave has a great change.

Based on zero-curvature equation, a series of new four-component nonlinear Schrödinger-type equations related to a $3\times 3$ matrix problem are proposed by using the polynomial expansion of the spectral parameter. As two special reductions, a generalized coupled nonlinear Schrödinger equation and a generalized coupled derivative nonlinear Schrödinger equation are obtained. And then, the infinite conservation laws for each of these four-component nonlinear Schrödinger-type equations are constructed with the aid of the Riccati-type equations.

Formation of laterally continuous ultrathin gold films on polymer substrates is a technological challenge. In this work, the vacuum thermal evaporation method is adopted to form continuous Au films in the thickness range of 7–17 nm on polymers of Poly(methyl-methacrylate-glycidly-methacrylate) and SU-8 film surface without using the adhesion or metallic seeding layers. Absorption spectrum, scanning electron microscope and atomic force microscope images are used to characterize the Au film thickness, roughness and optical loss. The result shows that molecular-scale structure, surface energy and electronegativity have impacts on the Au film morphology on polymers. Wet chemical etching is used to fabricate 7-nm thick Au stripes embedded in polymer claddings. These long-range surface plasmon polariton waveguides demonstrate the favorable morphological configurations and cross-sectional states. Through the end-fire excitation method, propagation losses of 6-$\mu \mathrm{\text{m}}$ wide Au stripes are compared to theoretical values and analyzed from practical film status. The smooth, patternable gold films on polymer provide potential applications to plasmonic waveguides, biosensing, metamaterials and optical antennas.

This work reports, microwave characterization of nanocrystalline nickel-polyvinylidene fluoride (n-Ni/PVDF) composites with an aim to explore their electromagnetic interference (EMI) shielding and absorption properties. The composites were fabricated using compression hot molding process at an optimum level of temperature and pressure. The electrical properties of the samples are computed using the measured scattering parameters in the X-band. The wave absorption capability of a single layer absorbing structure is theoretically evaluated by employing the computed electrical parameters. Besides, the shielding effectiveness (SE) of free standing samples are also calculated using transmission line model and compared with the experimentally obtained results to validate the theoretical model. High SE (42.87 dB) and absorption (−14.37) obtained in this work, suggest futuristic applications of n-Ni/PVDF composites for EMI shielding and wave absorption.

A new capacitive liquid level sensing interface weak-capacitance detection ASIC has been designed. This ASIC realized the detection of the output capacitance of the capacitive liquid level sensor, which converts the output capacitance of the capacitive liquid level sensor to voltage. The chip is fabricated in a standard $0.5\mu \mathrm{\text{m}}$ CMOS process. The test results show that the linearity of capacitance detection of the ASIC is 0.05%, output noise is $3.7\mathrm{\text{aF}}/\sqrt{\mathrm{\text{Hz}}}$ (when the capacitance which will be detected is 40 pF), the stability of capacitance detection is $7.4\times 10^{-5}\mathrm{\text{pF}}$ (1$\sigma$, 1h), the output zero position temperature coefficient is 4.5 uV/${}^{\circ }$C. The test results prove that this interface ASIC can meet the requirement of high accuracy capacitance detection. Therefore, this interface ASIC can be applied in capacitive liquid level sensing and capacitive humidity sensing field.

The single-, dual- and triple-wavelength passively mode-locked erbium-doped fiber lasers are demonstrated with MoS₂ and polarization-dependent isolator (PD-ISO). The saturable absorber is fabricated by wrapping an MoS₂ around a microfiber. The intracavity PD-ISO acts as a wavelength-tunable filter with a polarization controller (PC) by adjusting the linear birefringence. Single-wavelength mode-locked fiber laser can self-start with suitable pump power. With appropriate PC state, dual- and triple-wavelength operations can be observed when gains at different wavelengths reach a balance. It is noteworthy that dual-wavelength pulses exhibiting peak and dip sidebands, respectively, are demonstrated in the experiment. The proposed simple and multi-wavelength all-fiber conventional soliton lasers could possess potential applications in numerous fields, such as sensors, THz generations and optical communications.

The structural, magnetic, electronic and optical properties of Pbnm BiFeO${}_3$ (BFO), BiFe${}_{0.875}$Mn${}_{0.125}$O${}_3$ (BFM), Bi${}_{0.875}$X${}_{0.125}$Fe${}_{0.875}$Mn${}_{0.125}$O${}_3$ (XBFM) (X = Ce, Gd, Lu) have been investigated by the first principles within the PBE+U scheme. It is shown that the dopant Mn in the B sites and Ce (Gd, Lu) in the A sites improves the crystalline quality. The magnetic moments of Bi${}_{0.875}$Ce${}_{0.125}$Fe${}_{0.875}$Mn${}_{0.125}$O${}_3$ (CBFM) and Bi${}_{0.875}$Gd${}_{0.125}$Fe${}_{0.875}$Mn${}_{0.125}$O${}_3$ (GBFM) are 10 ${\mu }_{\mathrm{\text{B}}}$ and 16 ${\mu }_{\mathrm{\text{B}}}$ which mainly arises from the strongly localized unpaired 4f electrons of Ce and Gd, 3d electrons of Mn and Fe. While, as BFM, the magnetic moment of Bi${}_{0.875}$Lu${}_{0.125}$Fe${}_{0.875}$Mn${}_{0.125}$O${}_3$ (LBFM) is 9 ${\mu }_{\mathrm{\text{B}}}$ indicating no effect on the magnetization is made by Lu for its full 4f states. The densities of states of the five systems hint that CBFM is metallic and BFM, GBFM, LBFM are still semiconductors. The metallic properties of CBFM arise from the hybridization between Ce-4f and Mn-3d states which leads the Mn $3d^5$ states to be split into $t_{2g}^3$ and $e_g^2$ lowering the bottom of the conduction band to cross the Fermi level. Furthermore, we also study the optical properties of Pbnm BiFeO${}_3$ (BFO), BiFe${}_{0.875}$Mn${}_{0.125}$O${}_3$ (BFM), Bi${}_{0.875}$X${}_{0.125}$Fe${}_{0.875}$Mn${}_{0.125}$O${}_3$ (XBFM) (X = Ce, Gd, Lu). In this work, the optical properties including the absorption spectrum, loss function, refractive index and reflectivity spectrum are discussed in detail.

The structures of a flow field induced by a plasma actuator were investigated experimentally in quiescent air using high-speed Particle Image Velocimetry (PIV) technology. The motivation behind was to figure out the flow control mechanism of the plasma technique. A symmetrical Dielectric Barrier Discharge (DBD) plasma actuator was mounted on the suction side of the SC (2)-0714 supercritical airfoil. The results demonstrated that the plasma jet had some coherent structures in the separated shear layer and these structures were linked to a dominant frequency of $f_0$ = 39 Hz when the peak-to-peak voltage of plasma actuator was 9.8 kV. The high speed PIV measurement of the induced airflow suggested that the plasma actuator could excite the flow instabilities which lead to production of the roll-up vortex. Analysis of transient results indicated that the roll-up vortices had the process of formation, movement, merging and breakdown. This could promote the entrainment effect of plasma actuator between the outside airflow and boundary layer flow, which is very important for flow control applications.