Search

This paper presents a novel dual-band (DB) dual-polarized (DP) shared aperture antenna with high isolation by using a combination of microstrip dipoles and dielectric resonator antennas (DRAs) for S and C bands, respectively. In the S band, two sets of proximity coupled stacked microstrip dipoles which crossed at the center are employed to achieve dual-linear polarization (DLP) and obtain desired bandwidth (BW), isolation, and pure polarization. The rectangle DRA with hybrid feed is selected as the C band element for its advantages of small base area and high isolation, and a 2 × 2 array is presented with the “pair-wise” anti-phase feed technique to achieve a low cross-polarized level. Moreover, benefited from the back feed scheme, the proposed antenna has a symmetrical structure and has the potential of expanding into a larger aperture. The proposed antenna has been manufactured and measured, and the results agree well with simulations, which prove the validity of the proposed design.

To systematically evaluate the clinical efficacy of high-quality direct anterior approach (DAA) and other approaches for the treatment of elderly patients with femoral neck fracture.Literatures published in English or Chinese about the direct anterior approach and other approaches for hemiarthroplasty in femoral neck fracture were searched on Cochrane Library, PubMed, EMBASE, Web of science, Wanfang, CNKI databases from their establishment to May 2019. According to the inclusion and exclusion criteria, two researchers independently screened the literatures, and extracted the data. The quality of RCT were evaluated by Cochrane Risk of Bias Assessment Tool, and non-RCT were evaluated by the NOS scale. Meta-analysis was performed using the RevMan 5.3 software.A total of 9 articles were included with 901 cases, in which 429 cases used DAA, and 472 used other approaches. DAA had a significantly lower dislocation rate compared to subgroup of posterior and posterolateral approach [The current evidenceindicates that the DAA was associated with a significantly lower dislocation rate compared to posterior capsular approaches for hemiarthroplasty. There was no significant difference in dislocation rate with the lateral and anterolateral approach.

This paper proposes a microstrip antenna with reduced in-band and out-of-band radar cross-section (RCS) by subtracting the area of weak scattered current on the ground plane. Fourteen square slots were subtracted from the ground plane, reducing in-band and out-of-band RCS while maintaining radiation performance. Modified and reference antenna surface current distributions were simulated and analyzed in radiating and scattering modes. Two antenna prototypes were fabricated and measured to verify the simulation. The proposed antenna RCS was reduced compared with the reference antenna in the frequency range 1–4.4 GHz, including in-band and out-of-band frequency bands. Maximum in-band and out-of-band RCS reduction was 16.3 dBsm at the working frequency, and 19.3 dBsm at 3.4 GHz, respectively

In this study, a new microstrip patch antenna with wideband radar cross-section (RCS) reduction is presented. The RCS of the proposed antenna was reduced by subtracting the current-direction slots of the patch, with the radiation performance sustained not only for the current-direction subtraction, but also for the no modification in the ground plane. Modified and reference antenna were fabricated and measured. The simulation and measurement results showed that the modified antenna reduced the in-band and out-band RCS simultaneously with no detriment to the radiation performance. In the frequency band from 3.9 to 8.1 GHz, the RCS of the modified antenna was reduced in the whole band compared with the RCS of the reference antenna. The maximum RCS reduction was 7 dB at a frequency of 6.7 GHz.

In this paper, a coplanar waveguide (CPW)-fed dual-band uniplanar tri-polarization reconfigurable antenna based on the PIN diode switch is proposed. The proposed antenna can be reconfigured between the linear polarization (LP) and the circular polarization (CP) mode, including both the right-handed circular polarization and left-handed circular polarization simultaneously within the dual operating bands. The central frequencies of the bands are 2.63 and 4.42 GHz, respectively, and the overlapped operating bandwidth is 17.8 and 3.40%. The proposed reconfigurable antenna is a closed-slot antenna fed by the CPW transmission line and the reconfigurable mechanism is to regulate the T-shaped driven stub through switching the PIN diodes on and off. The scattering parameters, axial ratio, radiation pattern, gain, and the radiation efficiency of the proposed antenna are all investigated in the following. The optimized antenna has been fabricated to experimental test, the simulated and the measured results agree well with each other. The lower frequency band of the proposed antenna covers the 2.40 GHz WLAN specification and the upper band can be used for the 5 G communication (4.40–4.50 GHz); therefore it is suitable to be applied in the mobile wireless communication.

In this study, a dual-layered polarization and frequency reconfigurable microstrip antenna is proposed based on sequential mechanical axial rotation of the circular metal radiator. The antenna can be reconfigured among three different polarized modes, including the linear polarization (LP), left-handed circular polarization and right-handed circular polarization in the band from 4.68 to 4.80 GHz (2.53%). The resonance frequency of the proposed antenna with the same LP mode could also be tuned in the range from 4.70 to 5.03 GHz by mechanical rotation of the breach-truncated circular metal radiator as well as the circular substrate. Furthermore, the polarization characteristic and frequency can be reconfigured, respectively, as the circular radiator is taken an axial rotation with an angle of 360°. The presented antenna in the four different states has been numerically simulated and fabricated for the experimental measurement, the investigated characteristics includes the port reflection coefficient, axial ratio, radiation pattern, gain, and the radiation efficiency. The simulated and test results agreed well with each other. This antenna enriches the novel mechanical reconfigurable method except for the popular electrical approach.

In this article, a simple hexagonal metamaterial is presented. Different from the design method of parameters optimization, the method based on the analysis of the distributions of the electric field, magnetic field, and the surface current distribution is proposed. For verification of proposed analytic method, the retrieval process is carried out. Besides, the situations of the other two frequencies point are studied to further verify the analytic method. The experimental study is introduced as well. The results show that the negative effective permittivity and the negative effective permeability with pass band character is achieved simultaneously in the frequency range between 9.58 GHz to 9.75 GHz, and the comparison between the result of the analysis and the experiment justifies the proposed analytic method. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:720–726, 2017

A novel polarization-insensitive metasurface with angular stability for ultra-broadband (from 7 to 12 GHz) backscatter radar cross section (RCS) reduction is investigated. The proposed metasurface is composed of carefully arranged unit cells with spatially varied dimension, which can diffuse reflection uniformly and avoid the reflection in the specular direction. A proposed metasurface sample is fabricated and tested to validate RCS reduction behavior predicted by full-wave simulation software ANSYS HFSS. A more than 10 dB RCS reduction within the entire X-band is observed, indicating our metasurface may be potentially applied to future stealth technology.

A novel polarization-independent Mu-negative metamaterial with broad bandwidth named fan-shaped structure, composed of periodically arranged capacity-loaded fan-shaped patches symmetrically printed on the both side of a FR4 substrate, is theoretically and numerically investigated in this paper. First, the effective constitutive parameters are retrieved from the computed scattering parameters and are found having a negative permeability characteristic in the frequency range of 6.86–9.46 GHz, which is much wider than conventional split-ring resonator. Second, simplified equivalent LC models based on detailed study of field and surface current distribution, which can account for the characteristics of its electromagnetic behaviour, are introduced. Expressions of magnetic and electric resonance frequencies, deduced from the LC models, are presented as well. Finally, the dependence of the negative permeability characteristic on the system’s geometrical parameters is analysed through a parametric investigation....

A novel polarization insensitive metasurface for monostatic Radar Cross Section (RCS) reduction is designed, fabricated, and investigated. The proposed metasurface is comprised of carefully arranged unit cells with spatially varied dimension, which enables approximate uniform diffusion of incoming electromagnetic energy and avoids reflection at the specular direction. A theoretical model based on reflectarray theory is introduced to demonstrate the operating principle of the metasurface. By utilizing Gravitational Search Algorithm (GSA) and a fast far-field scattering pattern analysis method based on Inverse Fast Fourier transform technology (IFFT), a rapid and efficient design method is demonstrated. A metasurface sample is fabricated and tested to validate RCS reduction behavior predicted by full wave simulation. An over 20dB RCS reduction is observed in the vicinity of 9.5GHz, indicating our metasurface may be potentially applied in future stealth technology.

Lithium extraction from seawater and brine is an important approach to solving the short supply of lithium resource. Development of ion-sieve adsorption materials is the key of realizing industrial application of lithium extraction from seawater and brine with high ratio of magnesium to lithium. Although the synthetic process is complicated, with plenty of influencing factors, levels, and large amounts of data, this research successfully optimized the synthesis conditions by orthogonal experiment and statistical analysis. The achievements will lay solid foundation for the development of lithium adsorption materials.

To discuss clinical effects of surgical treatment for desmoplastic fibroma of bone.Between June 2000 and June 2010, 15 cases of desmoplastic fibroma were treated by surgical operation including 4 males and 7 females with an average age of 39 years old (ranged from 18 to 64 years old). The site of tumor was proximal femur in 4 cases, distal femur in 3, distal tibia in 2, proximal humerus in 1, distal humerus in 1, scapula in 1, pelvic in 2, manubrium of sternum in 1. The simple intralesional curettage was performed in 1 case. The other 14 cases were divided into two groups, 7 cases had an aggressive curettage with inactivation and the last 7 cases had a wide resection. Recurrence condition were observed after operation. The function was valuated in two groups after the operation according to Enneking's standard.The mean duration of follow-up was 56 months (ranged, 18 to 132 months). Two cases recurred, but no metastasis. The patient with simple intralesional curettage recurreed, 1 of the 7 patients with a wide resection recurred. The recurrence rate was 13.3% (2/15). There was no recurrence in the group with an aggressive curettage with inactivation. According to Enneking's standard, Enneking scoring was 21.6 +/- 3.8 in the group with a wide resection and 28.3 +/- 1.3 in another group, The results were excellent in 2 cases and good in 5 in the group with a wide resection, excellent in 7 in the other group.The aggressive curettage with inactivation has better functional recovery than the wide resection,and it should be chosen when the lesion is small or located in an area where reconstruction is difficult.

A novel polarization insensitive metasurface with over 25 dB monostatic radar cross-section (RCS) reduction is introduced. The proposed metasurface is comprised of carefully arranged unit cells with spatially varied dimension, which enables approximate uniform diffusion of incoming electromagnetic (EM) energy and reduces the threat from bistatic radar system. An iterative fast Fourier transform (FFT) method for conventional antenna array pattern synthesis is innovatively applied to find the best unit cell geometry parameter arrangement. Finally, a metasurface sample is fabricated and tested to validate RCS reduction behavior predicted by full wave simulation software Ansys HFSS[Formula: see text] and marvelous agreement is observed.

Matrine, one of the main active components of extracts from the dry roots of Sophora flavescens, has potent anti-tumor activity in various cancer cell lines. However, the activity of matrine against osteosarcoma remains unclear. In the present study, we examined the effects of matrine on human osteosarcoma cells and explored the underlying mechanism. Four human osteosarcoma cell lines: MG-63, U-2OS, Saos-2, and MNNG/HOS were treated by matrine and subjected to MTT assay, annexin V-FITC/PI double staining, and TUNEL assay. The activation of caspases and the expression of pro-apoptotic and anti-apoptotic factors were examined by qRT-PCR and Western blot. In addition, MNNG/HOS xenograft tumors were established in female nude BALB/c mice, and matrine was intraperitoneally (i.p.) administered to evaluate the anti-cancer capacity of matrine in vivo. We found that matrine inhibited the proliferation and induced apoptosis of the four osteosarcoma cell lines in vitro and induced the activation of caspase-3, -8, and -9 in a dose-dependent manner. Furthermore, the pro-apoptotic factors Bax and Fas/FasL were upregulated, and the anti-apoptotic Bcl-2 was downregulated. More importantly our in vivo, studies showed that administration of matrine decreased tumor growth in a dose-dependent manner. Immunohistochemistry analysis demonstrated the downregulation of Bcl-2 and upregulation of Bax and Fas/FasL in MNNG/HOS tumor tissues following matrine treatment, consistent with the in vitro results. Our results demonstrate that matrine inhibits the proliferation and induces apoptosis of human osteosarcoma cells in vitro and in vivo. The induction of apoptosis appears to occur through the upregulation of Fas/FasL and Bax, downregulation of Bcl-2, and activation of caspase-3, -8, and -9, which then trigger major apoptotic cascades.