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The grid-based Xin'anjiang model (GXM) has been widely applied to flood forecasting. However, when the model warm-up period is long and the amount of input data is large, the computational efficiency of the GXM is obviously low. Therefore, a GXM parallel algorithm based on grid flow direction division is proposed from the perspective of spatial parallelism, which realizes the parallel computing of the GXM by extracting the parallel routing sequence of the watershed grids. To solve data skew, a Directed Acyclic Graph (DAG) scheduling algorithm based on dynamic priority is proposed for task scheduling. The proposed GXM parallel algorithm is verified in the Qianhe River watershed of Shaanxi Province and the Tunxi watershed of Anhui Province. The results show that the GXM parallel algorithm based on grid flow direction division has good flood forecasting accuracy and higher computational efficiency than the traditional serial computing method. In addition, the DAG scheduling algorithm can effectively improve the parallel efficiency of the GXM.

Precipitation images play an important role in meteorological forecasting and flood forecasting, but how to characterize precipitation images and conduct rainfall similarity analysis is challenging and meaningful work. This paper proposes a rainfall similarity research method based on deep learning by using precipitation images. The algorithm first extracts regional precipitation, precipitation distribution, and precipitation center of the precipitation images and defines the similarity measures, respectively. Additionally, an ensemble weighting method of Normalized Discounted Cumulative Gain-Improved Particle Swarm Optimization (NDCG-IPSO) is proposed to weigh and fuse the three extracted features as the similarity measure of the precipitation image. During the experiment on similarity search for daily precipitation images in the Jialing River basin, the NDCG@10 of the search results reached 0.964, surpassing other methods. This indicates that the method proposed in this paper can better characterize the spatiotemporal characteristics of the precipitation image, thereby discovering similar rainfall processes and providing new ideas for hydrological forecasting.

A low radar cross section (RCS) slot array antenna based on absorptive frequency-selective structure (AFSS) is presented in this letter. The AFSS unit cell is constructed by two lossy layers and four double-sided parallel strip lines (DSPSLs). The radiation performance of the antenna can be preserved due to the transmission window of the lossy layers. Wide absorption bands of the AFSS are achieved due to periodic impedance of the DSPSL and the combination of the lossy layers. The operating principle of the design is demonstrated, and a prototype is fabricated and measured to validate the design. The proposed design features both wide RCS reduction band of the antenna and wide transmission band of the AFSS.

Tensor-based robust principal component analysis (PCA) methods are efficient to discover the low-rank part of a hyperspectral image for reducing redundant information and guarantee good classification results. However, current methods cannot remove noise adequately, and the residual noise remaining in the low-rank image limits the further improvement of classification performance. Thus, enhancing the robustness to noise is important and helpful for tensor-based robust PCA (RPCA) methods to process hyperspectral images. To this end, we propose a tensor-based RPCA method with a locality preserving graph and frontal slice sparsity (LPGTRPCA) for hyperspectral image classification. Specifically, a tensor $l_{2,2,1}$ norm that requires the frontal slice sparsity of a tensor is defined to extract the noise in the hyperspectral image from the frontal direction. What is more, a position-based Laplacian graph that preserves the local structures of a tensor according to the spatial position is designed for relieving the impact of the residual noise remaining in the low-rank image. Based on the tensor nuclear norm, the tensor $l_{2,2,1}$ norm, and the position-based Laplacian graph, LPGTRPCA efficiently separates the low-rank part with little noise from a raw hyperspectral image and achieves more robust classification results than current methods. LPGTRPCA is optimized by the alternative direction multiplier method (ADMM), and the convergence of solutions is experimentally demonstrated. In the experiments conducted on Indian Pines, Pavia University, and Salinas datasets, LPGTRPCA outperformed various state-of-the-art and classical tensor-based RPCA methods in terms of average class classification accuracy (AA), overall classification accuracy (OA), and kappa coefficient (KC).

A gain-enhanced antenna consisting of a bandpass frequency selective surface (FSS) and a patch antenna is initially proposed in this communication. By utilizing the reflection characteristic of the FSS, a quasi-Fabry–Perot (F-P) cavity is formed between the FSS and antenna’s ground, which considerably improves the gain of the antenna. Meanwhile, the bandpass FSS has a little phase compensation for oblique transmitting waves, which also slightly enhances the gain. Then a low-radar cross section (RCS) and gain-enhanced antenna is proposed by using absorptive/transmissive frequency selective structure (ATFSS). It is implemented by mounting the ATFSS above a patch antenna. The ATFSS is constructed by stacking a lossy layer above a bandpass FSS. Both antennas are fabricated, assembled, and measured. They achieve a gain-enhancement of 5.27 and 3.84 dB, respectively. Besides, the low-RCS antenna achieves 10 dB monostatic RCS reduction from 5 to 5.33 GHz and from 9 to 13.4 GHz under the TE-polarization, and from 8.4 to 13.5 GHz under the TM-polarization, respectively. Simulated results show it also achieves a good improvement in bistatic RCS reduction as well.

A wireless multistate controller based on radio frequency identification (RFID) technology for remote control applications is presented. The controller consists of a configurable RFID tag which has multiply alternative paths connecting to a multiway switch component. The main part of the tag is formed from the combination of loop and dipole to ensure balanced three-dimensional current responses and relatively stable impedances during path switching. With the proposed structure, the controller achieves a compact dimension of only 49 × 47 mm, a stable operation frequency band around the Federal Communications Commission (FCC) band (902–928 MHz), a quasi-isotropic radiation pattern with a gain variation less than 3 dB, as well as a control distance of 6.5–9.1 m in different configurations and directions. These features make the proposed controller a promising choice for wireless multistate remote control applications.

The attenuated X-ray transform arises from the image reconstruction in single photon emission computed tomography. The theory of attenuated X-ray transforms is so far incomplete and many questions remain open. In this paper, we are pursuing the inversion of the attenuated X-ray transforms with nonnegative varying attenuation functions μ. By the symmetric attenuated X-ray transform A μ on plane and the method of convolution-backprojection, we obtain the inversion formulas of the attenuated X-ray transforms with nonnegative attenuation functions μ, satisfying some decaying and smoothing conditions on plane.

Background To investigate short-term choroidal structural and vascular changes after epiretinal membrane (ERM) surgery. Methods In this retrospective study, 65 patients with unilateral ERM underwent pars plana vitrectomy combined with cataract surgery and were examined one day before surgery and one week, one month, and three months after surgery. Choroidal thickness (CT) and choroidal vascular index (CVI) were evaluated using horizontal enhanced depth imaging optical coherence tomography (EDI-OCT) scans and were further calculated using semi-automatic algorithms using MATLAB R2017a. Results Preoperatively, CVI was higher in eyes with ERM (61.70 ± 5.17%) than in fellow eyes (59.99 ± 5.26%). CVI increased significantly at one week after surgery (62.14 ± 5.02%) and decreased at 1 and 3 months after surgery (60.76 ± 4.97% and 60.4 ± 4.83%, respectively). The change was pronounced in the nasal region (p p p Conclusions Short-term postoperative variations in the choroid have been demonstrated in eyes with ERM. This may be related to the release of macular traction. CVI assessment using EDI-OCT may be a useful tool for investigating choroidal structural changes accompanying ERM and postoperative period.

Zika virus non-structural protein NS2A participates in viral replication, organization, and budding, as well as escaping host immunity. NS2A also involved in the induction of microcephaly by ZIKV. However, the above studies were mainly performed through NS2A with a tag due to the lack of available antibodies against NS2A. ZIKV NS2A is a multiplex transmembrane protein, which leads to difficulties in the preparation of its recognition antibodies, thus seriously affecting the study of ZIKV NS2A. In this study, we found that a peptide (GSTDHMDHFSLGVLC) derived from the N-terminal of ZIKV NS2A coupled to KLH induced antibodies recognizing ZIKV NS2A in rabbits. The purified polyclonal antibody recognized ZIKV NS2A in ZIKV-infected cells with high efficiency and specificity, as detected by western blot and immunofluorescence assay. Our study has important implications for the preparation of ZIKV NS2A antibodies and the in-depth study of ZIKV NS2A.

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne febrile disease caused by SFTS virus (SFTSV), or Dabie bandavirus, in the Phenuiviridae family. Clinically neurological disorders in SFTS have been commonly reported, but their neuropathogenesis has rarely been studied. Microglia are a type of neuroglia accounting for 10 to 12% of all cells in the brain. As resident immune cells, microglial cells are the first line of immune defense present in the central nervous system (CNS). Here, we report that SFTSV was able to infect microglial cells and stimulate interleukin 1β (IL-1β) secretion in the brains of infected neonatal BALB/c mice. We characterized the cell death induced in infected human microglial HMC3 cells, also susceptible to SFTSV, and found that the NOD-like receptor protein 3 (NLRP3) inflammasome was activated, leading to secretion of IL-1β and pyroptosis. Knockdown of NLRP3 or inhibition of the NLRP3 inflammasome activation suppressed the viral replication, suggesting that the activation of the NLRP3 inflammasome may support SFTSV replication in microglial cells. Viral nonstructural protein NSs, a known modulator of immune responses, interacted and colocalized with NLRP3 for the inflammasome activation. It appeared that the N-terminal fragment, amino acids 1 to 66, of NSs was critical to promote the assembly of the inflammasome complex by interacting with NLRP3 for its activation in microglial cells. Our findings provide evidence that SFTSV may cause neurological disorders through infecting microglia and activating the inflammasome through its nonstructural protein NSs for neural cell death and inflammation. This study may have revealed a novel mechanism of SFTSV NSs in dysregulating host response. IMPORTANCE Encephalitis or encephalopathy during severe fever with thrombocytopenia syndrome (SFTS) is considered a critical risk factor leading to high mortality, but there have been no studies to date on the pathogenesis of encephalitis or encephalopathy caused by SFTS virus. Here, we report that SFTSV infection can active the NLRP3 inflammasome and induce IL-1β secretion in the brains of infected newborn mice. In infected human HMC3 microglia, SFTSV activated the NLRP3 inflammasome via the viral nonstructural protein NSs through interaction with its N-terminal fragment. Notably, our findings suggest that the activation of the NLRP3 inflammasome may promote SFTSV replication in infected microglial cells. This study may reveal a novel mechanism by SFTSV to dysregulate host responses through its nonstructural protein, which could help us understand viral neuropathogenesis in SFTS patients.

The near-field coupling between closely placed metallic structures has been utilized to cope with the dilemma of a normal-mode helical antenna (NMHA) design. For small NMHAs, the impedance-matching difficulty is mitigated by designing appropriated coupling feeds, either electrically or magnetically. For long NMHAs, the radiation pattern distortion is rectified by dividing the complete helix into properly designed small sections. With mutual section coupling, the currents on all of the sections can be nearly in-phase, dictating an omnidirectional radiation pattern. The design principle has been described as twoelement models and a corresponding equivalent circuit analysis. The simulated and measured results show that, compared to conventional NMHAs, it is possible to design an NMHA of simultaneous good matching and radiation properties but with a much more flexible helix length and size.

A dual-polarized broad band-absorptive frequency-selective rasorber (FSR) is proposed in this article. The FSR has a lowpass band with low insertion loss and a broad absorption band. It is a two-layer structure formed by a lossy surface cascaded an absorptive transmission/reflection surface (ATRS), in which the ATRS is constructed by one substrate with a resistive square loop on its top side and a double square loop on its bottom side. The working mechanisms of the proposed ATRS and FSR are completely studied by using their equivalent circuit models. The ATRS retains dual stopbands of the double square loop and suppresses the unwanted transmission pole of the double square loop. Then a broadband absorptive FSR is achieved. A sample of the proposed FSR is fabricated and measured. The measured results show that the proposed FSR has a lowpass band up to 860 MHz ( $\vert S_{21}\vert \ge -1$ dB) and a broad absorption band with bandwidth of 95.3% from 3.84 to 10.83 GHz ( $\vert S_{11}\vert \le -10$ dB and $\vert S_{21}\vert \le -10$ dB).

Flaviviruses, including Dengue virus, Zika virus, Yellow fever virus, Japanese encephalitis virus, West Nile virus, cause thousands of deaths and millions of illnesses each year. The large outbreak of ZIKV in 2016 reminds us that flaviviruses can pose a serious threat to human safety and public health as emerging and re-emerging viruses. However, there are no specific drugs approved for the treatment of flavivirus infections. Due to no need to enter the cells, viral entry inhibitors have the unique advantage in suppressing viral infections. Flaviviruses bind to receptors and attach to the cell surface, then enter the endosome in a clathrin-dependent manner and finalizes the viral entry process after fusion with the cell membrane in a low pH environment. Small molecules, antibodies or peptides can inhibit flavivirus entry by targeting the above processes. Here, we focus on flavivirus entry inhibitors with well-defined target and antiviral activity. We hope that our review will provide a theoretical basis for flavivirus treatment and drug research and help to accelerate the clinical application of flavivirus entry inhibitors.

High temperatures are a major concern that limit rice germination and plant growth. Although previous studies found that melatonin can promote seed germination, the physiological regulation mechanism by which exogenous melatonin mediates high temperature tolerance during rice seed germination is still largely unknown. In order to overcome these challenges, the present study investigates the effects of melatonin on the characteristics of rice seed germination as well as on antioxidant properties, under different high temperature conditions. The results show that 100 μM melatonin seed-soaking treatment under high temperature conditions effectively improves the germination potential, the germination index, and the vigor index of rice seeds; increases the length of the shoot and the root; improves the activity of the antioxidant enzymes; and significantly reduces the malondialdehyde content. The gray relational grade of the shoot peroxidase activity and the melatonin soaking treatment was the highest, which was used to evaluate the effect of melatonin on the heat tolerance of rice. The subordinate function method was used to comprehensively evaluate the tolerance, and the results show that the critical concentration of melatonin is 100 μM, and the critical interactive treatment is the germination at 38 °C and followed by the recovery at 26 °C for 1 day + 100 μM. In conclusion, 100 μM of melatonin concentration improved the heat resistance of rice seeds by enhancing the activity of the antioxidant enzymes.

This communication presents a magnetic-material-loaded 3-D frequency-selective rasorber (FSR) consisting of independent transmission and absorption channels. The main feature of the proposed design is employing both ferrite material and meander line in the absorption channel to obtain a wide absorption band and low-loss transmission band. Detailed analysis of the absorption channel is given with the help of equivalent circuit models to demonstrate the operating principle. The design guidelines are formulated, and a design example is presented with both the simulated and measured results. The proposed FSR features both thin thickness and wide absorption bands. Moreover, no lumped components are required, which greatly facilitates the fabrication and reduces the cost.

Water level prediction of small- and medium-sized rivers plays an important role in water resource management and flood control. Such a prediction is concentrated in the flood season because of the frequent occurrence of flood disasters in the plain area. Moreover, the flood in mountainous areas suddenly rises and falls, and the slope is steep. Thus, establishing a hydrological prediction model for small- and medium-sized rivers with high accuracy and different topographic features, that is, plains and mountains, is an urgent problem. A prediction method based on ASCS_LSTM_ATT is proposed to solve this problem. First, the important parameters are optimized by improving the cuckoo search algorithm. Second, different methods are used to determine the forecast factors according to various topographic features. Finally, the model is combined with the self-attention mechanism to extract significant information. Experiments demonstrate that the proposed model has the ability to effectively improve the water level prediction accuracy and parameter optimization efficiency.

A three-dimensional (3-D) structure is proposed in this article for ultra-wideband absorber design. The ultra-wideband absorber is implemented by properly combining two subabsorbers. The first subabsorber operates in its fundamental mode ( $f_{0}$ ) and the third-order mode ( $3f_{0}$ ). Its lossy layer is designed with an infinite impedance at the second-order mode frequency ( $2f_{0}$ ). The second subabsorber is designed to operate in its fundamental mode frequency, which is corresponding to $2f_{0}$ of the first subabsorber. A double-sided parallel-strip line (DSPSL) is employed to produce the required infinite impedance of the first absorber. A simple equivalent circuit model of the DSPSL is established to explain the operating principle. A conventional parallel LC circuit is also provided for comparison to show the advantages of the DSPSL. Single-polarized and dual-polarized ultra-wideband absorbers are designed by combining these two subabsorbers, and their simulated fractional bandwidths (FBWs) of 151.6% and 150.9% are achieved, respectively. A prototype of the dual-polarized ultra-wideband absorber is fabricated and measured to validate the design concept. Its measured absorption band from 1.50 to 12.31 GHz with an FBW of 156.6% is in a good agreement with the simulated one. The proposed absorber features a wide absorption band and few lumped elements, which makes it more useful in practical applications.

Using a different method — the sphere method, which is based on the technique of changing the integral on a plane into the integral on a hemisphere, we give some concise inverse formulas of the Radon transforms of functions with support in a cone with vertex at the origin and flare angle less than π/2, or with compact support. These formulas are easy for the computer to operate and thus can be applied in the imaging techniques of computerized tomography.

The accurate and timely estimation of river discharge plays an important role in hydrological modeling, especially for avoiding the consequences of flood events. The majority of existing work on hydrologic prediction focuses on modeling the inherent physical process for specific river basins, while the geographic-connections between rivers are largely ignored. Geographically connected rivers provide rich spatial information that can be used to predict discharge amounts. In this paper, we study a novel problem of exploiting both temporal patterns and spatial connections for hydrological prediction. We construct three relationship graphs for hydrological gauges in the study area: the hydraulic distance graph, the Euclidean distance graph and the correlation graph. We fuse these graphs into one hydrological network graph, and propose a novel framework ST-Hydro which exploits Graph Convolutional Networks (GCN) for learning the spatial feature representations, and Recurrent Neural Networks with carefully designed activation functions for capturing temporal features simultaneously for hydrological prediction. Experimental results on real world data set demonstrate that the proposed framework can predict the river discharge effectively and at an early stage.

Discriminative correlation filters (DCFs) have been widely used in visual object tracking, but often suffer from two problems: the boundary effect and temporal filtering degradation. To deal with these issues, many DCF-based variants have been proposed and have improved the accuracy of visual object tracking. However, these trackers only adopt first-order data-fitting information and have difficulty maintaining robust tracking in unconstrained scenarios, especially in the case of complex appearance variations. In this paper, by introducing a second-order data-fitting term to the DCF, we propose a second-order spatial–temporal correlation filter (SSCF) learning model. To be specific, the SSCF tracker both incorporates the first-order and second-order data-fitting terms into the DCF framework and makes the learned correlation filter more discriminative. Meanwhile, the spatial–temporal regularization was integrated to develop a robust model in tracking with complex appearance variations. Extensive experiments were conducted on the benchmarking databases CVPR2013, OTB100, DTB70, UAV123, and UAVDT-M. The results demonstrated that our SSCF can achieve competitive performance compared to the state-of-the-art trackers. When penalty parameter λ was set to 10−5, our SSCF gained DP scores of 0.882, 0.868, 0.706, 0.676, and 0.928 on the CVPR2013, OTB100, DTB70, UAV123, and UAVDT-M databases, respectively.

Zika virus (ZIKV) is a positive-sense RNA flavivirus and can cause serious neurological disorders including microcephaly in infected fetus. As a mosquito-borne arbovirus, ZIKV enters bloodstream and is transmitted into the fetus through the placenta in pregnant women. Monocytes are considered one of the earliest blood cell types to be infected by ZIKV. As a first line defence, monocytes are crucial components in innate immunity and host responses and may impact viral pathogenesis in humans. Previous studies have shown that ZIKV infection can activate inflammasomes and induce proinflammatory cytokines in monocytes. In this report, we showed that ZIKV carried out a productive infection, which lead to cell death in human and murine monocytic cells. In addition to the presence of cleaved caspase-3, indicating that apoptosis was involved, we identified the cleaved caspase-1 and gasdemin D (GSDMD) as well as increased secretion of IL-1β and IL-18, suggesting that the inflammasome was activated that may lead to pyroptosis in infected monocytes. The pyroptosis was NLRP3-dependent and could be suppressed in the monocytes treated with shRNA to target and knockdown caspase-1, or an inhibited for caspase-1, indicating that the pyroptosis was triggered via a canonical approach. Our findings in this study demonstrate a concomitant occurrence of apoptosis and pyroptosis in ZIKV-infected monocytes, with multiple mechanisms involved in the cell death, which may have potentially significant impacts on viral pathogenesis in humans.

A wideband three-dimensional (3D) absorber based on a notch-slot resonator is proposed in this paper. A lossy coupled microstrip line was applied to eliminate the reflection band of the original lossy notch-slot resonator, resulting in a wide absorption band. A single-polarized design was first proposed, and the operating principle was demonstrated. Then, a dual-polarized design was presented, fabricated and measured. To eliminate the undesirable resonances caused by the securing slits cut between the two adjacent unit cells, some shorting pins were introduced. The measured results show that the dual-polarized absorber exhibits an absorption band from 2.74 GHz to 11.08 GHz (120.69% fractional bandwidth), and it is also stable under the incident angles up to 40° for both TE and TM polarizations.

This letter proposes a microwave planar sensor for the characterization of magnetodielectric materials. The sensor is designed by loading microstrip lines with complementary split-ring resonators (CSRRs). Two patches are connected to the microstrip lines to couple with the CSRRs, and a pair of 50- $\Omega $ resistors are in series with the lines to provide a notch. The designed sensor can extract the permittivity and permeability of the magnetodielectric materials simultaneously. A prototype of the designed sensor is fabricated and measured for validation of characterizing the magnetodielectric materials.

A novel frequency-selective rasorber (FSR) with a broad absorption band is proposed in this letter. The proposed FSR is realized by vertically cascading a two-dimensional (2-D) lossy layer with a 3-D band-stop frequency-selective structure (FSS). The 2-D lossy layer is composed of meandered square loops loaded with lumped resistors, and the 3-D band-stop FSS is constructed by parallel-plate waveguide arrays (PPWAs) stacked along the TE polarization direction (linear polarization perpendicular to the PPW). The band-absorptive FSR exhibits an absorption band (| S 11| ≤ –10 dB and | S 21| ≤ –10 dB) from 7.85 to 12.85 GHz and a low-pass band (| S 21| ≥ –1 dB) up to 3.8 GHz. Its transition efficiency of the transition band (FRap) is 2.1. A prototype is fabricated, and its measured results show that the proposed FSR has a low loss and flat low-pass band, a wide absorption band with high selectivity, and a steep transition band between the low-pass band and absorption band.

Miniaturised band-absorptive frequency selective rasorbers (FSRs) with wide absorption bands for single-polarised and dual-polarised applications are proposed here. These FSRs are both constructed by a lossy layer and a lossless layer, in which I-type metal strips are utilised to reduce the size of the unit cell of the FSRs. The equivalent circuit models (ECM) of the FSRs are presented and analysed. A prototype of the dual-polarised band-absorptive FSR is fabricated, assembled, and tested. The measured results show that a wide absorption band (| S 21 |≤–10 dB and | S 11 |≤–10 dB) from 3.93 GHz to 8.07 GHz with a bandwidth of 69%, and a low-pass band (| S 21 |≥–1 dB) with frequency lower than 880 MHz has been achieved for the dual-polarised band-absorptive FSR.

This study develops a differential-fed filtering patch antenna, which features superior frequency selectivity, compact size, low cross-polarisation, and symmetrical radiation patterns. The proposed antenna consists of a rectangular patch on the top layer, which is differentially fed by a balun bandpass filter on the bottom layer. A pair of rectangular coupling slots were etched on the middle layer for energy coupling. The patch antenna performs not only as the radiator but also as the last resonator of the whole filter circuit for compactness. A prototype of the proposed filtering antenna operating at 2.45 GHz was fabricated and tested. The measured in-band peak gain is 5.9 dBi with steep roll-off at band edges, and the out-of-band gain is less than - 25 dBi. Moreover, symmetrical radiation patterns and low cross-polarisation levels of - 22 dB are also realised for the proposed filtering antenna.

A multilayer structure and magnetic ferrite material are employed to expand the absorption bandwidth of 3-D frequency-selective rasorber (FSR). Resonant-like ferrite is used to realize the magnetic loss with high selectivity of absorption over a wide frequency band, while the multilayer structure is proposed to achieve multiple absorption peaks at designated frequencies. Combining the loaded ferrite material with multilayer structure can realize wide absorption bands. Equivalent circuit models are utilized to understand the operating mechanism of the described 3-D structure and to guide the design of multilayer structure with selected ferrite materials. Two broadband 3-D FSRs are designed, fabricated, and measured. Both designs achieve the sextuple bandwidth ratio with reflectivity less than −10 dB, and the absorption band with a bandwidth ratio of >2.6:1 can be achieved at either lower or upper absorption band, respectively.

This paper presents a 3D band-absorptive frequency selective rasorber (FSR). Such an FSR is absorptive within a specific band and almost transparent below the absorption band. The definition and evaluation of the band-absorptive FSR is initially provided and followed by the design concept of 3D FSR. An example is then proposed, whose unit cell is composed of 3D absorber and 3D band-stop FSS. An equivalent circuit model is established for understanding its operating principle. A prototype of the proposed 3D band-absorptive FSR is fabricated. The measured results show that it has an absorption band ( $\vert S_{11}\vert \le -10$ dB and $\vert S_{21}\vert \le -10$ dB) from 4.21 to 6.51 GHz, with a thickness of 0.17 wavelength at 4.21 GHz. Moreover, $\vert S_{21}\vert $ is higher than −1 dB at the frequencies below 1.28 GHz. The proposed band-absorptive FSR can be used as radomes for low-frequency antennas in military communications or spectrum monitoring systems.

Viral infections are one of the leading causes in human mortality and disease. Broad-spectrum antiviral drugs are a powerful weapon against new and re-emerging viruses. However, viral resistance to existing broad-spectrum antivirals remains a challenge, which demands development of new broad-spectrum therapeutics. In this report, we showed that fludarabine, a fluorinated purine analogue, effectively inhibited infection of RNA viruses, including Zika virus, Severe fever with thrombocytopenia syndrome virus, and Enterovirus A71, with all IC50 values below 1 μM in Vero, BHK21, U251 MG, and HMC3 cells. We observed that fludarabine has shown cytotoxicity to these cells only at high doses indicating it could be safe for future clinical use if approved. In conclusion, this study suggests that fludarabine could be developed as a potential broad-spectrum anti-RNA virus therapeutic agent.

Severe fever with thrombocytopenia syndrome (SFTS) is an acute infectious disease caused by a novel phlebovirus (SFTSV), characterized by fever, thrombocytopenia and leukocytopenia which lead to multiple organ failure with high mortality in severe cases. The SFTSV has spread rapidly in recent years and posed a serious threat to public health in endemic areas. However, specific antiviral therapeutics for SFTSV infection are rare. In this study, we demonstrated that two peptides, SGc1 and SGc8, derived from a hydrophobic region of the SFTSV glycoprotein Gc, could potently inhibit SFTSV replication in a dose-dependent manner without apparent cytotoxicity in various cell lines and with low immunogenicity and good stability. The IC50 (50% inhibition concentration) values for both peptides to inhibit 2 MOI of SFTSV infection were below 10 μM in L02, Vero and BHK21 cells. Mechanistically, SGc1 and SGc8 mainly inhibited viral entry at the early stage of the viral infection. Inhibition of SFTSV replication was specific by both peptides because no inhibitory effect was shown against other viruses including Zika virus and Enterovirus A71. Taken together, our results suggested that viral glycoprotein-derived SGc1 and SGc8 peptides have antiviral potential and warrant further assessment as an SFTSV-specific therapeutic.

Apoptosis, pyroptosis and necroptosis are regulated processes of cell death which can be crucial for viral disease outcomes in hosts because of their effects on viral pathogenicity and host resistance. Zika virus (ZIKV) is a mosquito-borne flavivirus, which infects humans and can cause neurological disorders. Neural developmental disorders and microcephaly could occur in infected fetuses. Several types of nervous cells have been reported to be susceptible to ZIKV infection. Human astrocytes play important roles in the nutritional support and defense of neurons. In this study, we show that human astrocytes are susceptible to ZIKV infection and undergo progressive cell death after infection. In infected astrocytes we detected no cleavage or activation of pro-caspase-3 and pro-caspase-1. Apoptotic substrates and increased secretion of interleukin (IL)-1β or IL-18 were not detected, either. These ruled out the occurrence of apoptosis or pyroptosis in ZIKV-infected astrocytes. We detected, however, an increase of phosphorylated receptor-interacting serine/threonine-protein kinase (RIPK)1, RIPK3, and mixed lineage kinase domain-like (MLKL) protein, indicating that programmed necrosis, or necroptosis, was induced in infected astrocytes. The phosphorylation and cell death were inhibited in cells pre-treated with GSK’872, an inhibitor of RIPK3, while inhibition of RIPK1 with an inhibitor, Necrostatin-1, had no effect, suggesting that ZIKV-induced necroptosis was RIPK1-independent in astrocytes. Consistent with this finding, the inhibition of RIPK1 had no effect on the phosphorylation of MLKL. We showed evidence that MLKL phosphorylation was RIPK3-dependent and ZBP-1, which could stimulate RIPK3, was upregulated in ZIKV-infected astrocytes. Finally, we demonstrated that in GSK’872-pre-treated astrocytes, viral replication increased significantly, which indicates that necroptosis may be protective against viral replication in astrocytes. Our finding that astrocytes uniquely underwent necroptosis in response to ZIKV infection provides insight and helps us better understand the viral pathogenesis in the ZIKV-infected central nervous system.

A 3D dual-polarized frequency selective rasorber (FSR) using magnetic material and meander-line is presented in this paper, which consist of the absorption and transmission channels. The wide absorption band is produced by the absorption channel consisting of the short-ended parallel-plate waveguide (PPW) loading the magnetic material and the meander-line, while the transmission band is produced by the open-ended lossless PPWs. The magnetic material is lossless in the transmission band resulting in the low-loss in transmission window, therefore the incoming EM waves cannot be absorbed by the absorption channel. An absorption band from 5.02 GHz to 9.60 GHz and a transmission band from 13.6 GHz to 16.4 GHz are obtained in the FSR presented, with the fractional bandwidth of 62.65% and 18.67% respectively. The thickness is 0.18λ a at 5.02 GHz. The experimental results shows that the presented FSR exhibits the advantages of dual-polarization and wide absorption. And no lumped components required reduced the fabrication cost greatly.