Active spintronic-metasurface terahertz emitters with tunable chirality

The ability to manipulate the electric-field vector of broadband terahertz waves is essential for applications of terahertz technologies in many areas, and can open up new possibilities for nonlinear terahertz spectroscopy and coherent control. Here, we propose a novel laser-driven terahertz emitter, consisting of metasurface-patterned magnetic multilayer heterostructures. Such hybrid terahertz emitters can combine the advantages of spintronic emitters for being ultrabroadband, efficient and flexible, as well as those of metasurfaces for the unique capability to manipulate terahertz waves with high precision and degree of freedom. Taking a stripe-patterned metasurface as an example, we demonstrate the generation of broadband terahertz waves with tunable chirality. Based on experimental and theoretical studies, the interplay between the laser-induced spintronic-origin currents and the metasurface-induced transient charges/currents are investigated, revealing the strong influence on the device functionality originated from both the light-matter interactions in individual metasurface units and the dynamic coupling between them. Our work not only offers a flexible, reliable and cost-effective solution for chiral terahertz wave generation and manipulation, but also opens a new pathway to metasurface-tailored spintronic devices for efficient vector-control of electromagnetic waves in the terahertz regime

Flexible generation of structured terahertz fields via programmable exchange-biased spintronic emitters

Structured light, particularly in the terahertz frequency range, holds considerable potential for a diverse range of applications. However, the generation and control of structured terahertz radiation pose major challenges. In this work, we demonstrate a novel programmable spintronic emitter that can flexibly generate a variety of structured terahertz waves. This is achieved through the precise and high-resolution programming of the magnetization pattern on the emitter surface, utilizing laser-assisted local field cooling of an exchange-biased ferromagnetic heterostructure. Moreover, we outline a generic design strategy for realizing specific complex structured terahertz fields in the far field. Our device successfully demonstrates the generation of terahertz waves with diverse structured polarization states, including spatially separated circular polarizations, azimuthal or radial polarization states, and a full Poincare beam. This innovation opens a new avenue for designing and generating structured terahertz radiations, with potential applications in terahertz microscopy, communication, quantum information, and light-matter interactions

RP-HPLC DETERMINATION OF GINSENOSIDES RG1 AND RB1 IN PANAX GINSENG FRUITS

Background: At present, there has been a lot of research at home and abroad on the roots, stems and leaves of Panax Ginseng as well as their extracts, but the fruits of Panax Ginseng have been relatively little studied. Materials and Methods: To establish a method for determination of ginsenosides Rg1 and Rb1 in Panax Ginseng fruits. RP-HPLC method is adopted, column used is a ZOBAX SB-C18 column (4.6 mm × 250 mnl, 5 μm), mobile phase A is water, and B is acetonitrile, gradient elution conditions are: 0~20 min (A:B 20:80), 20~60 min (A:B 20~35: 80~65); and detection wavelength 203 nm. Results: Ginsenosides Rgl and Rb1 have good linear relationships within the ranges of 1.04~10.40 μg and 0.50~5.00 μg, respectively, and r is 0.9998 and 0.9997; reproducibility and recovery of the method are both in line with requirements. Conclusion: The method established is simple, accurate and fast, which is suitable for the simultaneous determination of ginsenosides Rg1 and Rb1 in Panax Ginseng fruits

Abstraction of man-made shapes

Man-made objects are ubiquitous in the real world and in virtual environments. While such objects can be very detailed, capturing every small feature, they are often identified and characterized by a small set of defining curves. Compact, abstracted shape descriptions based on such curves are often visually more appealing than the original models, which can appear to be visually cluttered. We introduce a novel algorithm for abstracting three-dimensional geometric models using characteristic curves or contours as building blocks for the abstraction. Our method robustly handles models with poor connectivity, including the extreme cases of polygon soups, common in models of man-made objects taken from online repositories. In our algorithm, we use a two-step procedure that first approximates the input model using a manifold, closed envelope surface and then extracts from it a hierarchical abstraction curve network along with suitable normal information. The constructed curve networks form a compact, yet powerful, representation for the input shapes, retaining their key shape characteristics while discarding minor details and irregularities.Science, Faculty ofComputer Science, Department ofGraduat

Detection of S-nitrosylated protein by surface plasmon resonance

S-Nitrosylation has recently emerged as an important posttranslational modification of proteins and is becoming an intensive field of research in plants. Protein S-nitrosation, a reversible post-translation modification of cysteine, affects many cell signaling pathways and plays critical roles in redox-sensitive cell signaling. Changes in protein function effectively transmit biological signals and thus provide a framework for elucidating signaling networks. This paper presented a new, universal immunosensor for detection of S-nitrosylated proteins. Electrochemical impedance spectroscopy (EIS) and atomic force microscope (AFM) were used to estimate the formation of self-assembled film. This method was based on the specific binding characteristics of biotin–streptavidin, using Biotin-HPDP labeled protein sulfhydryl group as the substrate to detect proteins. The sensor was used to detect bovine serum albumin (BSA), nitrosylated BSA and denitrosylated BSA. The results showed that 90.61% of nitrosylated BSA were reduced, verifying that protein S-nitrosylation is a reversible and effective post-translation modification. This method was successfully applied to detect S-nitrosylated protein in Feicheng peach. The results showed good repeatability and precision. This method provided a molecular basis for further exploring the mechanism of S-nitrosylation of proteins in plants