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This paper presents a new ultra-wideband(UWB) high-gain dual-band common-aperture array antenna. The antenna consists of four T-shaped dual-polarized antennas, a 6×6 waveguide slot array antenna, and a circular metal substrate. The dual-polarized antenna operates from 2.33 to 12 GHz and uses a large metal Vivaldi antenna array that sits above the metal plate. The waveguide slot antenna array operates in the X-band with 9.8～10.3 GHz and is located below the metal plate. The dual-polarization antenna array and the waveguide slot antenna array are located in the same plane and separated by a circular metal plate, which can improve the space utilization and can effectively reduce the mutual coupling between the antennas and solve the problem of poor isolation effect of common-aperture antenna. This article uses HFSS software simulating, the simulation results show that the common- aperture antenna array has the advantages of high polarization isolation, ultra-wideband, high gain, high aperture efficiency, and is suitable for modern communication systems and electronic countermeasures.

In this study, a molecularly imprinted polymer (MIP) was synthesized using trichlorfon as a template molecule. The MIP exhibited a high adsorption capacity toward trichlorfon. Using bovine serum albumin as a carrier, trichlorfon hapten was indirectly labeled with luminol, which competed with free trichlorfon for the combination with a biomimetic antibody of MIP. Based on this direct competitive format, a high throughput flow-injection chemiluminescent biomimetic immunoassay method was developed for fast detection of trace trichlorfon. The influencing factors were investigated and optimized. Under the optimal condition, a lower limit of detection (IC15) of 0.0024 mg/L was obtained using this method. This method was also used to detect the trichlorfon spiked in carrot and cabbage samples, and the results were also verified using the method of gas chromatography. [ABSTRACT FROM AUTHOR]

Fructose and its polysaccharides are widely found in fruits and vegetables, with the Maillard reaction of fructose affecting food quality. This study aimed to investigate the Maillard reaction of fructose using a fructose–histidine model system. The reaction process was characterized using fluorescence spectroscopy and ultraviolet spectroscopy. The effects of temperature, initial reactant concentration, initial fructose concentration, initial histidine concentration, and initial pH value on the different stages of the Maillard reaction were studied. Reactant reduction, ultraviolet and fluorescence spectra, acetic acid content, 5-hydroxymethylfurfural (5-HMF) content, and browning intensity were evaluated. The results showed that increasing the temperature and reactant concentration promoted the condensation reaction of fructose and amino acid in the early stage, the formation of intermediate products with ultraviolet absorption and fluorescence in the intermediate stage, and the formation of pigment in the final stage. The 5-HMF concentration decreased with increasing histidine concentration and initial pH value. Changes in the shape of ultraviolet and fluorescence spectra showed that the initial pH value affected not only the reaction rate, but also the intermediate product types. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging rate of the Maillard reaction products increased with increasing temperature, reactant concentration, and initial pH value. [ABSTRACT FROM AUTHOR]

Fructose and its polysaccharides are widely found in fruits and vegetables, with the Maillard reaction of fructose affecting food quality. This study aimed to investigate the Maillard reaction of fructose using a fructose⁻histidine model system. The reaction process was characterized using fluorescence spectroscopy and ultraviolet spectroscopy. The effects of temperature, initial reactant concentration, initial fructose concentration, initial histidine concentration, and initial pH value on the different stages of the Maillard reaction were studied. Reactant reduction, ultraviolet and fluorescence spectra, acetic acid content, 5-hydroxymethylfurfural (5-HMF) content, and browning intensity were evaluated. The results showed that increasing the temperature and reactant concentration promoted the condensation reaction of fructose and amino acid in the early stage, the formation of intermediate products with ultraviolet absorption and fluorescence in the intermediate stage, and the formation of pigment in the final stage. The 5-HMF concentration decreased with increasing histidine concentration and initial pH value. Changes in the shape of ultraviolet and fluorescence spectra showed that the initial pH value affected not only the reaction rate, but also the intermediate product types. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging rate of the Maillard reaction products increased with increasing temperature, reactant concentration, and initial pH value.