Manipulating vector solitons with super-sech pulse shapes

Theoretical simulations about manipulating vector solitons with super-sech pulse shapes are conducted based on an optical fiber system in this manuscript. By changing temporal pulses’ parameters when orthogonally polarized pulses have the same or different input central wavelengths, output modes in orthogonal directions will demonstrate different properties. When input orthogonal modes have the same central wavelength, “2+2” pseudo-high-order vector soliton can be generated when time delay is changed. While under the condition of different central wavelengths, orthogonal pulses with multiple peaks accompanied with two wavelengths can be achieved through varying projection angle, time delay or phase difference. Our simulations are helpful to the study of optical soliton dynamics in optical fiber system.

Docked ions: vertical-aligned tubular arrays for highly efficient capacitive deionization

Capacitive deionization (CDI) is an effective method for desalination of brackish water to alleviate the global freshwater crisis. Obtaining high desalination capacity is the primary focus of this field. Based on electrical double layer (EDL) theory, current research is mainly devoted to increasing the specific surface area of electrode materials, however, the NaCl adsorption capacity is typically limited to the range of 10 - 20 mg g−1. In this work, we propose a new design paradigm of using a vertical-aligned nanotubular structure for CDI. This design allows ions to be temporarily held inside the electrodes like ships docked in a harbor (ion-docking effect, IDE) due to the greatly diminished water flow inside the tubes, thus enhancing the desalination capacity. As a result, the obtained CDI device based on vertical-aligned nanotubular P-TiO2 arrays shows an ultra-high NaCl adsorption capacity of ~60 mg g−1 within 30 minutes in 0.01 mol L−1 NaCl solution under 1.2 V, corresponding to a rapid average adsorption rate of 2 mg g−1 min−1. Moreover, the adsorption capacity could be further increased up to 121 and 136 mg g−1 under 1.2 and 1.5 V for 2.5 hours adsorption, respectively, but still far from its equilibrium value. Finally, experiments and theoretical simulations are combined to further understand the IDE in CDI. This work highlights the discovery and the utilization of IDE in CDI, and provides new guidance for the design of CDI electrodes and can facilitate the development of CDI technology.

Theoretical and Experimental Investigation on SPR Gas Sensor Based on ZnO/Polypyrrole Interface For Ammonia Sensing Applications

This work includes the exploitation of laboratory-assembled SPR technique for the application of gas sensor at room temperature. The refractive index change at the interface of ZnO/Polypyrrole with adsorption of gases (NO2 and NH3) is the basis of SPR gas sensor. The theoretical simulations were done to find out the optimum thickness of ZnO and Polypyrrole composite films for sharp SPR reflectance values. Theoretical SPR curves obtained by changing the value of thickness of Gold nanoparticles film and incident wavelength are also presented in the manuscript. Experimental studies were done to validate the theoretical studies and discussion were done about the interaction of NH3 gas with prism/Au/ZnO/Polypyrrole system. Here, ZnO/Polypyrrole multilayer structure is the sensing layer to develop highly efficient SPR based NH3 gas sensor. The outcome of these results validate the significance of SPR technique for application of interaction of surface adsorbed analytes, with the interface of dielectrics and sensing material.

Tuning scalar spin chirality in ultrathin films of the kagome-lattice ferromagnet Fe3Sn

Non-coplanar spin textures with finite scalar spin chirality can be artificially induced at surfaces and interfaces through the interfacial Dzyaloshinskii-Moriya interaction. However, stabilizing a proper magnetic skyrmion crystal via this route remains elusive. Here, using an epitaxial bilayer of platinum and geometrically frustrated kagome-lattice ferromagnet Fe3Sn, we show the possible formation of a two-dimensional skyrmion crystal under well-regulated Fe3Sn thickness conditions. Magnetization measurements reveal that the magnetic anisotropy is systematically varied from an inherent in-plane type to a perpendicular type with the thickness reduction. Below approximately 0.5 nm, we clearly detect a topological Hall effect that provides evidence for finite scalar spin chirality. Our topological Hall effect analysis, combined with theoretical simulations, not only establishes its interfacial Dzyaloshinskii-Moriya interaction origin, but also indicates the emergence of a stable skyrmion crystal phase, demonstrating the potential of kagome-lattice ferromagnets in spin chirality engineering using thin-film nanostructures.

The corrosion behavior and cracking susceptibility of the disbonded coating in the X80 steel pipeline by theoretical simulations and experimental measurements

The corrosion behavior and cracking susceptibility of the disbonded coating in the X80 steel pipeline were investigated by different methods. The oxygen content in the trapped solution decreased rapidly with the formation of an airtight disbonded area. The airtight system affected the electrode reaction process, resulting in the inhibition of corrosion in the center of the disbonded area and the more refined surface finish of the sample. The bottom of the disbonded area underwent a relatively intense and accelerated corrosion reaction controlled by the diffusion process. The cracking susceptibility of the X80 steel firstly decreased and then increased in the pointing direction.

The Deformation Behavior and Bending Emissions of ZnO Microwire Affected by Deformation-Induced Defects and Thermal Tunneling Effect

The realization of electrically pumped emitters at micro and nanoscale, especially with flexibility or special shapes is still a goal for prospective fundamental research and application. Herein, zinc oxide (ZnO) microwires were produced to investigate the luminescent properties affected by stress. To exploit the initial stress, room temperature in situ elastic bending stress was applied on the microwires by squeezing between the two approaching electrodes. A novel unrecoverable deformation phenomenon was observed by applying a large enough voltage, resulting in the formation of additional defects at bent regions. The electrical characteristics of the microwire changed with the applied bending deformation due to the introduction of defects by stress. When the injection current exceeded certain values, bright emission was observed at bent regions, ZnO microwires showed illumination at the bent region priority to straight region. The bent emission can be attributed to the effect of thermal tunneling electroluminescence appeared primarily at bent regions. The physical mechanism of the observed thermoluminescence phenomena was analyzed using theoretical simulations. The realization of electrically induced deformation and the related bending emissions in single microwires shows the possibility to fabricate special-shaped light sources and offer a method to develop photoelectronic devices.