Search

This study aims to investigate the inhibitory effect of Pien Tze Huang(PZH) on enterovirus 71(EV71). To be speci-fic, chemiluminescence method was adopted to evaluate the toxicity of PZH to African green monkey kidney(Vero) cells and human rhabdomyosarcoma(RD) cells, and cytopathic effect(CPE) method to assess the inhibition on EV71-GFP reporter virus and EV71 C4 wild-type virus. The results showed that PZH had low cytotoxicity to Vero cells and RD cells, with the half-maximal cytotoxic concentration(CC_(50)) of about 0.691 3-0.879 2 mg·mL~(-1) for the two. In addition, PZH can effectively inhibit the replication of EV71 within the non-cytotoxic concentration range, and dose-dependently alleviate the cytopathic changes caused by virus infection, with the half-maximal effective concentration(EC_(50)) of 0.009 2-0.106 3 mg·mL~(-1). On the basis of the above results, the green fluorescent protein(GFP), indirect immunofluorescence assay(IFA), and median tissue culture infective dose(TCID_(50)) were employed to assess and verify the anti-EV71-GFP and anti-EV71 C4 activity of PZH. The results demonstrated that PZH can dose-dependently lower the expression of GFP by EV71-GFP and structural protein VP-1 by EV71 C4 and decrease the production of progeny infectious viruses. The EC_(50) of PZH for EV71-GFP and EV71 C4 was about 0.006 0-0.006 2 mg·mL~(-1) and 0.006 6-0.025 6 mg·mL~(-1), respectively. This study suggested that PZH may exert antiviral activity by acting on EV71 and interfering with the expression of VP-1. At the moment, there is still a lack of specific anti-EV71 drugs. This study proposed a new idea for the symptomatic treatment of EV71 infections such as hand-foot-mouth disease and verified an effective drug for the treatment of EV71 infections.

Electromagnetic analysis for microstrip antenna and packaging structures is formulated by volume-surface integral equations (VSIEs). The conducting microstrip and ground are described with SIEs, while the dielectric substrate is governed by volume integral equations (VIEs), and they are coupled to each other to form VSIEs. Using VIEs instead of SIEs for dielectric substrate can improve the conditioning of system matrix related to the multiscale property of antenna and packaging structures. The VSIEs are usually solved by the method of moments (MoM) with well-designed basis functions defined over conforming meshes, resulting in much inconvenience of implementation. We propose a mixed approach to solve the VSIEs by combining the traditional MoM for the conducting part and a point-matching scheme for the dielectric part together. The approach uses cuboids to discretize the dielectric substrate and does not require conforming meshes between the conducting and dielectric parts. Also, the approach considers the thickness of metallic microstrip and ground, which is usually neglected. Typical numerical examples are presented to demonstrate the proposed approach, and its effectiveness has been verified.

In this paper, the well-known high frequency structure simulator (HFSS)is used to design an ultra-high-frequency (UHF)radio-frequency-identification (RFID)tag antenna with a paper substrate. With the continuous development of RFID technology, various factors of designing RFID tags have been investigated such as the substrate material, tag shape, working frequency band, and impedance matching. In the design of passive tag antenna, the impedance matching, broadband, and miniaturization are the main difficulties. We use a special structure to improve the performance of passive tag antenna and an UHF RFID tag antenna with a paper substrate is proposed for near-field applications. The tag antenna uses a matching network to achieve the impedance matching and employs a first-order Hilbert fractal structure to reduce the size. The overall size of the antenna is 63.6mm⨯25mm and the operation band is from 881.9 MHz to 962.2 MHz which can cover the UHF RFID bands of many countries. Its good performance is verified by HFSS simulation and measurement.

Most of the insulator faults will result in rising of surface temperature and cause a high temperature region of the insulator. Therefore, it is an effective way to accurately identify the high temperature region of the insulator. In this paper, a high temperature region identification method for insulators based on BP neural network is proposed. After the infrared image is segmented, the training model will be optimized by the extracting of texture feature, calculating with the gray-level co-occurrence matrix, and applying the energy, entropy, moment of inertia and correlation as eigenvalues. The experimental results show that the method has high accuracy and can provide reference for the identification of the high temperature region of the transmission line insulator.

In this paper, we investigate the resonant frequency of the antenna with the mechanical deformation and a wireless rectangular patch antenna is presented and optimized. The simulation result indicates a good linearity between the resonant frequency shift and mechanical deformation in three directions, which are longitudinal, transverse and oblique directions, respectively. In addition, in order to make it more accurately in many applications, approximate relationship among these three directions has been given in this work.

A model-based inverse algorithm combined with the curl-conforming volume integral equation method is presented for inversion of anisotropic material permittvities from scattered fields. The forward algorithm uses the curl-conforming volume integral equation method. The inversion algorithm is based on the Gauss-Newton method. Numerical examples show the effectiveness of the inversion algorithm and demonstrate the sensitivities of measurements to the anisotropic objects.

Volume integral equations (VIEs) are indispensable to formulate inhomogeneous or anisotropic electromagnetic (EM) problems and cuboid meshes are preferred to discretize volume domains in some applications. In solving the VIEs, accurate evaluation for singular integrals is very essential but there is no direct method to evaluate hypersingular integrals over a cuboid domain so far. In this work, we propose some closed-form formulas for calculating those hypersingular volume integrals and they are simpler and more efficient to implement. A numerical example is presented to demonstrate the formulas and their effectiveness has been verified.

Electromagnetic (EM) scattering by bi-isotropic objects is formulated through volume integral equations (VIEs). The VIEs are usually solved by the method of moments (MoM) in which unknown flux densities are expanded with the Schaubert-Wilton-Glisson (SWG) or other divergence-conforming basis functions, but the approach may not be convenient in implementation because material parameters are involved in integrands. We propose a point-matching scheme to solve the VIEs in which current densities are selected as unknown functions to be solved and integral kernels are free of material parameters, resulting in a facilitation of implementation for bi-isotropic media. A typical numerical example is presented to demonstrate the scheme and its robustness has been verified.

Biological tissues like breasts are dispersive inhomogeneous dielectric objects and microwave imaging for them can be formulated by volume integral equations (VIEs). The distorted Born iterative method (DBIM) is used to reconstruct the objects in recent years, but it requires to update the dyadic Green's function in each iteration and is also sensitive to the initial guess of object property. We use the contrast source inversion method (CSIM) to image the objects by updating the contrast source and contrast simultaneously. The CSIM can avoid the direct solution of dyadic Green's function and does not need an initial guess for the object property. A numerical example is presented to demonstrate the approach and good results have been obtained.

In this paper, a low-profile microstrip monopole antenna with an ultrawide bandwidth (UWB) is proposed. Via holes, rectangular patches, and a tune stub connecting ground plate are employed to improve the gain and impedance bandwidth of the antenna. Meanwhile, the antenna is etched on a single-layer substrate lowering the cost and complexity of manufacturing process. HFSS software is used to design and optimize the antenna's parameters. The novel antenna with the size of 45 mmx50 mm has the resonant frequency of 2.45 GHz, bandwidth of 1.6 GHz. The peak gain of the antenna is from −1.8 dBi to 0.75 dBi against frequency from 1.4 GHz to 3.0 GHz.

The objective of the study was to investigate the feasibility of a single-dose hepatitis B vaccine based on three kinds of poly (D, L)-lactide-co-glicolide acid (PLGA) microspheres. PLGA microspheres loaded with recombinant hepatitis B surface antigen (HBsAg) were formulated using a double emulsion microencapsulation technique. The pharmaceutical characteristics of size, surface morphology, protein loading efficiency, antigen integrity, release of HBsAg-loaded PLGA microspheres and degradation of the polymer in vitro were evaluated. The degradation of the polymer corresponded with the composition of the polymer (lactide/glycolide ratio), molecular weight of the polymer (viscosity) and morphology of the microspheres. These PLGA microspheres were able to continuously release antigen under conditions that mimic the environment in vivo. The single subcutaneous injection of HBsAg-loaded PLGA50/50 microspheres, PLGA75/25 microspheres and a mixture of PLGA50/50, PLGA75/25, and PLGA50/50-COOH microspheres in mice resulted in comparable serum antibody titers to those of three injections of the conventional aluminum adjuvant formulated HBsAg vaccine. Based on these findings in vitro and in vivo, it was concluded that HBsAg was successfully loaded into the PLGA microspheres, which can auto-boost an immune response, and the HBsAg-loaded PLGA microsphere is a promising candidate for the controlled delivery of a vaccine.

To investigate the level of immune response and the immune mechanism of the single-dose hepatitis B surface antigen (HBsAg)-poly (d, l)-lactide-co-glicolide acid (PLGA) microspheres in BALB/c mice.Three kind of HBsAg-PLGA microspheres, HBsAg-PLGA50/50-COOH microspheres, HBsAg-PLGA75/25 microspheres and HBsAg-PLGA50/50 microspheres, were prepared by double emulsion microencapsulation technique used three kinds of PLGA with different L/G ratio. The single-dose of HBsAg-PLGA microspheres was subcutaneously injected into BALB/c mice at the dose of 7.5 microg HBsAg per mouse. The conventional aluminum-adjuvant vaccine was subcutaneously injected at 0, 1 and 2 month as positive control. In certain time interval, the induced immune level of total antibody was detected by enzyme linked immunosorbent assay (ELISA). For subclass of IgG antibody and cytokines studies, the dose of HBsAg was 2.5 microg per mouse.The HBsAg-PLGA microspheres could successfully induce a humoral immune response in BALB/c mice. Compared with the conventional aluminum-adjuvant vaccine, the antibody response of the HBsAg-PLGA50/50-COOH microspheres was significantly lower than the group received three injections of aluminum-adjuvant vaccine (P0.01) except for a higher priming response during the early 6 weeks. The results were ascribed to the relatively rapid degradation charactics of PLGA50/50-COOH polymer. The immune response for the HBsAg-PLGA50/50 microspheres and HBsAg-PLGA75/25 microspheres were comparable to the group administered with aluminum-adjuvant vaccine (P0.05) which was due to the sustained degradation of PLGA50/50 and PLGA75/25 polymer.The HBsAg-PLGA microsphere is a promising candidate for the controlled delivery of a vaccine which does not require multiple injections.