A Novel Differentially-Fed Dual-Polarized Filtering Antenna for Base Station

The theory, design and experiments of a wideband dual-polarized filtering antenna are presented. A novel technique, which combines the use of open loops, parasitic loop, and extended ground plane, is proposed to realize two upper band radiation nulls and a lower band radiation null. Thanks to these radiation nulls, the proposed antenna obtains a sharp cut-off at the edges of the operating band. To achieve wideband performance, another novel technique of exciting multiple resonant modes of the crossed dipoles and parasitic loop is proposed. The measured results demonstrate that this antenna achieves a wide impedance bandwidth from 1.7 to 3.01 GHz (56%), high isolation of 38dB, low cross-polarization within the working frequency band and also filtering performance. At 3.17 GHz, the gain of the antenna will drop rapidly to -18.1 dBi, which is 26.4 dB lower than the average in-band gain. These advantages make the proposed antenna a good candidate for base station applications

Decoupling of Dual-Band Dual-Polarized Base Station Array Antenna

Dual-band dual-polarized arrays (DBDPA) using interleaved configuration have drawn industry attention as a promising way to improve channel capacity in a package that has a minimum width. By integrating high-performance filtering elements, a novel interleaved DBDPA for base station use is presented in this paper. For the first time, a radiation null is introduced into the low-band (LB) antenna using the intrinsic suppression mode of folded dipole. Then, to enhance the gain-suppression level in out-of-band to 16 dB, four rectangular loops are introduced under the radiator. To achieve high selectivity for high-band (HB) antenna, a meander line loop is introduced and analyzed for the first time in this paper. Simulations indicate that the presented HB antenna achieves 17 dB of out-of-band rejection and 243 dB/GHz of roll-off rate. The combined use of these two filtering elements finally enables the realization of a DBDPA with low mutual coupling and low cross-band scattering. According to the measurements, this antenna covers two wide frequency ranges of 2.26- 2.73 GHz and 2.98- 4.3 GHz with a 25 dB cross-band isolation level

Dynamical analysis of a heterogeneous spatial diffusion Zika model with vector-bias and environmental transmission

In this study, we formulate a reaction-diffusion Zika model which incorporates vector-bias, environmental transmission and spatial heterogeneity. The main question of this paper is the analysis of the threshold dynamics. For this purpose, we establish the mosquito reproduction number $R_{1}$ and basic reproduction number $R_{0}$. Then, we analyze the dynamical behaviors in terms of $R_{1}$ and $R_{0}$. Numerically, we find that the ignorance of the vector-bias effect will underestimate the infection risk of the Zika disease, ignorance of the spatial heterogeneity effect will overestimate the infection risk, and the environmental transmission is indispensable

Three-Dimensional Simulation of the Shrinkage Behavior of Injection-Molded Poly Lactic Acid (PLA): Effects of Temperature, Shear Rate and Part Thickness

The effects of injection temperature, shear and part thickness on the linear shrinkage of injection-molded poly (lactic acid) (PLA) were intensively analyzed using the Autodesk Moldflow software. The obtained results showed that both melt temperature and shear rate had obvious effects on the linear shrinkage of PLA, i.e., the linear shrinkage of PLA increases significantly with the increase of melt temperature and shear rate. In addition, the shrinkage of high-crystallinity PLA was remarkably larger than that of low-crystallinity PLA, and thin-walled parts was larger than thick-walled ones in shrinkage

Differentially Fed Dual-Band Base Station Antenna with Multimode Resonance and High Selectivity for 5G Applications

A dual-polarized antenna with multimode resonance and high selectivity is proposed in this paper to cover the 5G sub-6 GHz bands. The proposed antenna achieves dual wide impedance bandwidth characteristics by incorporating a dual mode coupled patch and four planar coupled strips around the driven patch. Through the four resonant modes of these structures, the antenna effectively covers the two desired frequency bands. Moreover, the electric/magnetic coupling between the driven patch, dual mode coupled patch, and planar coupled strips enables the creation of three radiation nulls that suppress unwanted radiation. To further improve the out-of-band rejection level and half power beamwidth, four shorted strips are introduced around the radiator. The introduction of these strips results in a 4th radiation null at higher out-of-band frequencies and expands the antenna's half power beamwidth from 52° to 62°. To demonstrate the feasibility of the design, both the proposed antenna and its array were manufactured and tested. Measured results show that the filtering element was able to operate within frequency bands of 3.24-3.83 GHz (16.7%) and 4.74-5.30 GHz (11.2%) with a reference of |Sdd11| < -14 dB. The input ports exhibited a high level of isolation, measuring 40 dB. Furthermore, the four radiation nulls proved effective in suppressing out-of-band radiation

A Wideband Dual-Polarized Filtering Antenna for Multi-Band Base Station Application

A dual-polarized filtering antenna with wide impedance bandwidth and good rejection level in n78 (3.3-3.8 GHz) and n79 (4.8- 5.0 GHz) bands is realized in this paper. By deftly exciting the inherent radiation nulls of the dual-coaxial-fed dipole antenna, good out-of-band rejection levels can be achieved in both the lower frequency band and the n79 band. Then, by replacing the ordinary dipole arms with split loop resonators, new adjustable radiation null can be obtained in the n78 band. The effective length of the split loop resonator can be changed to conveniently alter this radiation null. To confirm the design principle, a prototype of the proposed design was made and tested. The fabricated prototype achieves a wide impedance bandwidth of 52% (1.69- 2.87 GHz) which can cover all established 1.71–2.69 GHz LTE bands. Besides, the proposed antenna realizes good gain suppression levels at the n78 and n79 bands. The tested mutual coupling between its differential input ports is lower than -40 dB

Differential Characterization of Two Kinds of Stem Cells Isolated from Rabbit Nucleus Pulposus and Annulus Fibrosus

Objective. Nucleus pulposus (NP) and annulus fibrosus (AF) are two main components of intervertebral disc (IVD). We aimed to figure out whether NP and AF also contain stem cells and whether these stem cells share common properties with chondrocytes and/or fibroblasts in their phenotypes or whether they are completely different types of cells with different characteristics. Design. The disk cells were isolated from AF and NP tissues of the same lumbar spine of the rabbits. The properties of these disk cells were characterized by their morphology, population doubling time (PDT), stem cell marker expression, and multidifferentiation potential using tissue culture techniques, immunocytochemistry, and RT-PCR. Results. Both disk cells formed colonies in culture and expressed stem cell markers, nucleostemin, Oct-4, SSEA-4, and Stro-1, at early passages. However, after 5 passages, AFSCs became elongated and NPSCs appeared senescent. Conclusion. This study indicated that IVD contains stem cells and the characteristics of AFSCs and NPSCs are intrinsically different. The findings of this study may provide basic scientific data for understanding the properties of IVD cells and the mechanisms of lower back pain

Contents of Heavy Metals in Typical Aquatic Products from a Market in Binzhou

To evaluate the levels of heavy metal pollution and risks in consumption of aquatic products from a market in Binzhou, the contents of Cu, Zn, Cd, Cr and Pb in the edible part of eight aquatic species such as Ctenopharyngodon idellus were determined by inductively coupled plasma mass spectrometry. The results show that the levels of the five elements differed among different species of aquatic products. The ability of bivalves to accumulate heavy metals was significantly higher than that of fish. Compared with relevant food hygiene standards, there was a certain excess of Cr in Ruditapes philippinarum and Penaeus vannamei. The results of human exposure risk assessment show that the THQ values of the heavy metals in the eight aquatic species were all less than 1, indicating that the consumption of these aquatic products had no potential non-carcinogenic risks

The Dual-Targeted Peptide Conjugated Probe for Depicting Residual Nasopharyngeal Carcinoma and Guiding Surgery

Detecting residual nasopharyngeal carcinoma (rNPC) can be difficult because of the coexistence of occult tumours and post-chemoradiation changes, which poses a challenge for both radiologists and surgeons using current imaging methods. Currently, molecular imaging that precisely targets and visualises particular biomarkers in tumours may exceed the specificity and sensitivity of traditional imaging techniques, providing the potential to distinguish tumours from non-neoplastic lesions. Here, we synthesised a HER2/SR-BI-targeted tracer to efficiently position NPC and guide surgery in living mice. This bispecific tracer contained the following two parts: IRDye 800 CW, as an imaging reagent for both optical and optoacoustic imaging, and a fusion peptide (FY-35), as the targeting reagent. Both in vitro and in vivo tests demonstrated that the tracer had higher accumulation and longer retention (up to 48 h) in tumours than a single-targeted probe, and realised sensitive detection of tumours with a minimum size of 3.9 mm. By visualising the vascular network via a customised handheld optoacoustic scan, our intraoperative fluorescence molecular imaging system provides accurate guidance for intraoperative tumour resection. Integrating the advantages of both optical and optoacoustic scanning in an intraoperative image-guided system, this method holds promise for depicting rNPC and guiding salvage surgery