Josephson junctions based on amorphous MoGe: prospects for use in superconducting electronics

We have fabricated and characterized all-MoGe Josephson junctions with a very thin Al/AlOx/(Al) barrier, where the amorphous MoGe films exhibit superconducting transition temperatures up to 7 K. Due to the uniformity of the surface morphology of the MoGe films, the junctions demonstrate high uniformity of their tunneling properties. The experimental data on the temperature dependence of the subgap current agree well with theoretical calculations. The results obtained imply that Josephson tunnel junctions based on amorphous superconductors are promising candidates for use in superconducting electronics, especially in applications requiring multiple stacked junctions or the creation of a nonequilibrium quasiparticle distribution.

Generation of high-uniformity and high-resolution Bessel beam arrays through all-dielectric metasurfaces

Bessel beam arrays are progressively attracting attention in recent years due to their remarkable non-diffracting nature and parallel manipulation capabilities in diverse applications. However, the poor phase discretization of conventional approaches such as spatial light modulators leads to low numerical aperture (NA) beam arrays due to the limitation imposed by the Nyquist sampling theorem and poor uniformity of the beam intensity. The key contribution of this study is to experimentally demonstrate the generation of high-uniformity and high-resolution Bessel beam arrays by utilizing all-dielectric metasurfaces. This is attained by optimizing the design of the supercell of a Dammann grating, particularly decreasing each supercell of the grating to a proper size. We demonstrate a 4 × 4 array of Bessel beams with a subwavelength transverse dimension (570 nm, ∼0.9λ) and a large NA of 0.4 for each beam in the array, while maintaining a relatively high uniformity intensity (52.40%) for the array. Additionally, the Bessel beam arrays are generated in a broadband range through the proposed all-dielectric metasurfaces. Our results are of great significance and particularly useful for applications of metasurface-based Bessel beam arrays in multidisciplinary fields such as laser fabrication, biomedical imaging, data storage, and multi-particle trapping.

High efficiency five-element trap detector with low optical losses

We have constructed a 5-element trap detector using 10 x 10 mm UVG100 photodiodes. The trap exhibits high uniformity of responsivity (±100 part per million) and ultra-low reflectance losses (mostly below 1 part per million) throughout the visible range. Responsivity and quantum efficiency measurements indicate close to ideal performance between 360 nm and 680 nm within the expanded measurement uncertainty of 0.25 %–0.15 %. The UVG trap can be considered as an absolute detector between these wavelengths and as a cheaper and a simpler alternative to the custom-made Predictable Quantum Efficient Detector for use in photometric and radiometric applications.

Features of Functionalization of the Surface of Alumina Nanofibers by Hydrolysis of Organosilanes on Surface Hydroxyl Groups

Small additions of nanofiber materials make it possible to change the properties of polymers. However, the uniformity of the additive distribution and the strength of its bond with the polymer matrix are determined by the surface of the nanofibers. Silanes, in particular, allow you to customize the surface for better interaction with the matrix. The aim of our work is to study an approach to silanization of nanofibers of aluminum oxide to obtain a perfect interface between the additive and the matrix. The presence of target silanes on the surface of nanofibers was shown by XPS methods. The presence of functional groups on the surface of nanofibers was also shown by the methods of simultaneous thermal analysis, and the stoichiometry of functional groups with respect to the initial hydroxyl groups was studied. The number of functional groups precipitated from silanes is close to the number of the initial hydroxyl groups, which indicates a high uniformity of the coating in the proposed method of silanization. The presented technology for silanizing alumina nanofibers is an important approach to the subsequent use of this additive in various polymer matrices.

Design of a High Uniformity Laser Sheet Optical System for Particle Image Velocimetry

Particle image velocimetry (PIV) is a non-contact, instantaneous and full-flow velocity measurement method based on cross-correlation analysis of particle image. It is widely used in fluid mechanics and aerodynamics. Laser sheet optical system is one of the key equipment of PIV, and it is an important guarantee to obtain high definition particle image. In the PIV measurement task of large low speed wind tunnel, in order to solve the problem of sheet light illumination uniformity of large size model and take into account the requirements of PIV technology on the thickness of the sheet light, a hybrid algorithm is used to design a high uniformity laser sheet optical system based on the theory of physical optics. The simulation results show that the size of the sheet light is 400 mm ×1 mm, the diffraction efficiency reaches 97.77%, and the non-uniformity is only 0.03%. It is helpful to acquire high-resolution images of particles in the full field of view. It also can be applied to a series of non-contact flow field measurement techniques such as plane laser induced fluorescence, filtered Rayleigh scattering and two-color plane laser induced fluorescence temperature measurement.

Investigation of Droplet Size Distribution for Vibrating Mesh Atomizer

Vibrating mesh atomizers (VMA) are increasing in demand for various aerosol applications due to their ability to generate uniformly sized droplets. Currently there are two types of VMA (commercial metallic membranes and silicon based). High Uniformity and control of small droplet size are the basic requirements for many aerosol applications, for which ultrasonic or VMA are employed. However, there is limited research on understanding the droplet size distribution of different types of atomizers. In this study three aerosol generators were investigated: Ultrasonic, metallic VMA, and MEMS-based silicon VMA. The primary objective was to compare these devices on droplet size distribution and mechanism of action. A systematic study to compare the performance of the two VMA was investigated based on droplet distribution, volumetric median diameter (VMD) using liquids with different physiochemical properties. Size distribution of the droplet produced by the metallic VMA was twice the span compared to silicon VMA for fluids with viscosity <2cP. The metallic VMA also resulted in an increase in VMD as the viscosity increased, whereas the Si VMA did not see a significant increase in VMD. The silicon-based VMA demonstrated a 4-15x increase in fine particle fraction control compared to metallic VMA. The results demonstrate that silicon based VMA has narrower droplet distribution with more uniform droplet size and lower span compared to metallic VMA.

Transcriptome based identification and validation of heat stress transcription factors in wheat progenitor species Aegilops speltoides

Wheat, one of the major cereal crops worldwide, get adversely affected by rising global temperature. We have identified the diploid B genome progenitor of wheat, Aegilops speltoides (SS), as a potential donor for heat stress tolerance. Therefore, the present work was planned to study the total transcriptome profile of heat stress-tolerant Ae. speltoides accession pau3809 (AS3809) and compare with that of tetraploid and hexaploid wheat cultivars PDW274 and PBW725, respectively. The comparative transcriptome was utilized to identify and validate heat stress transcription factors (HSFs), the key genes involved in imparting heat stress tolerance. Transcriptome analysis led to the identification of a total of 74 K, 68 K, and 76 K genes in AS3809, PDW274, and PBW725, respectively. There was a high uniformity of GO profiles under the biological, molecular, and cellular functions across the three wheat transcriptomes, suggesting the conservation of gene function. Twelve HSFs having the highest FPKM value were identified in the AS3809 transcriptome data, while six of these HSFs namely HSFA3, HSFA5, HSFA9, HSFB2a, HSFB2b, and HSFC1b, were validated with qRT PCR. These six HSFs were identified as an important component of thermotolerance in AS3809 as evident from their comparative higher expression under heat stress.