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The hippocampus is the most common seizure focus in people. In the hippocampus, aberrant neurogenesis plays a critical role in the initiation and progression of epilepsy in rodent models, but it is unknown whether this also holds true in humans. To address this question, we used immunofluorescence on control healthy hippocampus and surgical resections from mesial temporal lobe epilepsy (MTLE), plus neural stem-cell cultures and multi-electrode recordings of ex vivo hippocampal slices. We found that a longer duration of epilepsy is associated with a sharp decline in neuronal production and persistent numbers in astrogenesis. Further, immature neurons in MTLE are mostly inactive, and are not observed in cases with local epileptiform-like activity. However, immature astroglia are present in every MTLE case and their location and activity are dependent on epileptiform-like activity. Immature astroglia, rather than newborn neurons, therefore represent a potential target to continually modulate adult human neuronal hyperactivity.

This paper demonstrates a packaged THz shunt capacitor micro-electromechanical systems (MEMS) switch with low insertion loss. In-line shunt switch is used to achieve a low loss in THz band, which is realized by reducing the equivalent parallel inductance of switch. The equivalent circuit of the switch is analyzed systematically, the equivalent resistance is obtained based on the skin effect of high frequency current on the conductor and the current density distribution characteristics of the conductor cross-section. The equivalent capacitance is obtained by using “double microstrip” characteristic impedance calculation method, and the correction factor ( $\Delta$ ) is introduced to calculate the equivalent inductance accurately. By optimizing equivalent circuit parameters and switch sizes, the structure of MEMS switch with low loss and high isolation characteristics are achieved. The switch is packaged by rectangular waveguide and achieved a low insertion loss. The comparison between the switch simulation results and the equivalent circuit simulation results verify that the parameter extraction method and circuit analysis are correct. The packaged MEMS switch is measured, and the results are in an acceptable agreement with simulation, the switch is actuated under voltage of ~30V. The measured result has achieved a low insertion loss with less than < 2dB from 220 to 280GHz, and isolation with ~16 dB from 240GHz to 320GHz in the “down” state.

A ±45° polarization diversity dipoles’ antenna is designed and fabricated by 3-D printing technology in combination with mussel-inspired surface chemistry. For the fabrication of metal-coated 3-D antenna, mussel-inspired surface functionalization and electroless deposition technique were used for metallization of printed antennas. A dopamine-based coating layer was attached onto the printed antenna by heterogenetic-induced polymerization, to capture catalyst moieties for conducting electroless metal deposition on the surface and enabling the function of antenna. To prevent particle oxidation on the surface of copper, a method of antioxidation and anticorrosion protection for the copper layer is proposed without reducing the conductivity of antenna. In addition, a method based on surface treatment and rapid electrodeposition is proposed, which solves the problem of metal layer falling off in the traditional 3-D printing antenna structure. The 3-D printing antenna is measured, and the results show a good agreement with the simulated results. Both the simulated and measured results show that a port-to-port isolation >26 dB with VSWR 28 dB can be achieved for the proposed antenna. The 3-D printing antenna performances indicated that resin-based 3-D printing technology is promising in fabricating the antennas with lightweight and complex structures.

This paper demonstrates a 340-GHz band pass filter with a low insertion loss of ~-0.6 dB and a bandwidth of ~6%. This paper studies the relationship between filter diaphragm thickness and resonator length, and the quantitative relationship between insertion loss and fabrication tolerances. The diaphragm is quantitatively analyzed and the resonators lengths with correction factors are calculated for the accurate and robust filter parameters, and the simulation results based on calculated parameters show a robust filter structure as well as a good agreement with the theoretical analysis. The surface roughness and filter structure sizes deviation with different tolerances are studied and calculated for insertion loss. Finally, a filter with low insertion loss and good robustness is achieved by calculated parameters and a certain fabrication tolerance. Different fabrication precisions are carried out to verify the effect of size tolerances on the filter performance, including insertion loss and structural robustness. The filters, designed by the parameters analysis and fabricated by ≤ ~7.5-μm accuracy show good agreement between the simulation results and the test results, and when fabricated accuracy is ~5 μm, the insertion loss is ~-0.6 dB and the return loss is

This paper presents a novel miniaturization 90° phase shifter using parallel coupled inductors and capacitors. The size reduction is achieved by replacing the quarter-wavelength transmission lines in a conventional fixed 90 degrees phase shifter with the resonator circuit. The resonator circuit, formed by the parallel coupled inductors and capacitor, provides a 90° phase shift at 45 MHz. In this way, the circuit size can be largely reduced without sacrificing the operation bandwidth and power handling. The inductors structure used in the phase shifter carries high power, which consists of two full coupled rectangle metal coils. The proposed miniature fixed phase shifter is then applied to the design of a directional coupler centered at 45 MHz. The measured results show a bandwidth of 40–50 MHz for better than 35 dB return loss with a phase shift of ~ 90°, a deviation within ~ 2°, and power handling of 63 dBm (2 kW). Notably, the proposed fixed phase shifter occupies an area of 58.5 mm $\times30.5$ mm $\times33$ mm, which is only about $0.009\,\,\lambda _{\mathbf {0}}\times 0.0045\,\,\lambda _{\mathbf {0}}\times 0.005\,\,\lambda _{\mathbf {0}}$ at 45 MHz.

A switchable bandpass filter is presented in this paper, which is able to operate at two different frequencies. The “open-ring” resonators and cantilever microelectromechanical systems (MEMSs) switches are employed to form the switchable filter with a high rejection at out-of passband and a controlled dc bias of 26 V. A hybrid resonance circuit with both series circuit and parallel circuit are used as the equivalent circuit, which is used to accurately analyze the structure parameters. The MEMS switch capacitance, used for equivalent circuit and driving voltage estimation, is analyzed to achieve an exact predicted value by equivalent microstrip line model. The isolation of designed MEMS switch is greater than 40 dB with awideband from4 to 9GHz, the filter is switched on and off to achieve the center frequency at ~7.81 and ~8.35 GHz separately. The filter is fabricatedon high-resistance silicon, and the measured results showed a good agreement with the simulated results. The filter performance shows a sharp rejection greater than 40dB at the frequency of ( ${\textsf {f}}_{ { {{\textsf {0}}}}} \pm 0.5$ GHz), and the insertion loss is >−3.4 dB in the passband.

This letter demonstrates a terahertz (THz) bandpass filter with a center frequency of ~340 GHz, low insertion loss of ~ −0.6 dB, and bandwidth of ~5.3%. The diaphragm thickness is quantitatively analyzed to obtain accurate filter parameters based on equivalent circuit and diaphragm coupling in THz band for the first time, and the simulation results based on calculated filter parameters show that diaphragm thickness has great influence on the filter performance. The test results show a good agreement with the theoretical analysis and simulation results. Meanwhile, the relationship between fabrication error and insertion loss was discussed and a quantitative mathematical model is given. The filter also shows an excellent performance when compared with the performance of other filters from the current literature reports.

In this paper, a non-planar conformal dual-polarized phased array antenna is proposed. The design of non-planar conformal antenna and optimized simulations are presented. The antenna design is based on a dual-polarized patch antenna element with vertical orthogonal baluns. The antenna element is backed by a compact cavity, to reduce the inter-element mutual coupling and to enhance the scanning performance of the curved conformal array. The proposed array achieves a wide fractional bandwidth of over 20%, when scanning up to ±45° in E and H planes. The validity of design is confirmed by simulation outcomes of 10 × 10 array model.

A conformal half-Yagi antenna is proposed in this work which can realize the directional pattern along the axial cylinder metal carrier. The antenna is designed based on the monopole antenna and traditional Yagi antenna. The proposed antenna is composed of an active monopole, one reflector pole and three director poles which are designed on the ground plane according to the operation frequency range. The proposed antenna achieves a wide bandwidth of over 20% from 14 GHz to 18 GHz which broken through the bandwidth limit of the traditional Yagi antenna. The design and optimization for the antenna was conducted in this work, and the simulated results of the maximum gain is about 8.7 dBi in the direction 25 degree offset from axial. And the gain is about 5 dBi in the axial direction, the beam width is about 89 degree in the azimuth direction and about 32 degree in the elevation direction. The S 11 is less than −15 dB in the frequency range of 14 GHz to 18 GHz. The prototype of the antenna is fabricated by the NC milling process on a whole aluminum plate which can obtain the good mechanical strength performance. The measured results of the S 11 and the gain can agree with the simulated results. The dimension of the prototype antenna is about 50 mm × 30 mm × 10 mm, and the height of the prototype antenna protruding the surface of the conformal carrier is only about 5 mm. And the weight of the prototype antenna is about 14.8 g which is suitable for installing on the platform of conformal cylinder metal carrier which required the light weight for microwave communication.

This paper presents a novel J band (220&ndash, 325 GHz) MEMS switch design. The equivalent circuits, the major parameters, capacitance, inductance and resistance in the circuit were extracted and calculated quantitatively to carry out the radio frequency analysis. In addition, the mechanical property of the switch structure is analyzed, and the switching voltage is obtained. With the designed parameters, the MEMS switch is fabricated. The measurement results are in good agreement with simulation results, and the switch is actuated under a voltage of ~30 V. More importantly, the switch has achieved a low insertion loss of ~1.2 dB at 220 GHz and &lt, ~4 dB from 220 GHz to 270 GHz in the &ldquo, UP&rdquo, state, and isolation of ~16 dB from 220 GHz to 320 GHz in the &ldquo, DOWN&rdquo, state. Such switch shows great potential in the integration for terahertz components.

SUMMARYStem cell dysfunction drives many age-related disorders. Identifying mechanisms that initially compromise stem cell function represent early targets to enhance stem cell behavior later in life. Here, we pinpoint multiple factors that disrupt neural stem cells (NSC) in the adult hippocampus. We find that NSCs exhibit asynchronous maintenance by identifying short-term (ST-NSC) and intermediate-term NSCs (IT-NSCs). ST-NSC divide rapidly to generate neurons and deplete in the young brain. Meanwhile, multipotent IT-NSCs persist for months, but are pushed out of homeostasis by lengthening quiescence. Single cell transcriptome analysis of deep NSC quiescence revealed several hallmarks of biological aging in the mature brain and identified tyrosine-protein kinase Abl1 as an NSC pro-aging factor. Treatment with the Abl-inhibitor Imatinib increased NSC proliferation without impairing NSC maintenance in the middle-aged brain. Further intersectional analysis of mature NSC with old epidermal, hematopoietic and muscle stem cell transcriptomes identified consensus changes in stem cell aging. Our study elucidates multiple origins of adult neurogenesis decline and reveals that hippocampal NSCs are particularly vulnerable to a shared stem cell aging signature.

A simple soluble salt-driven matrix swelling method was developed for fast fabrication of a silver nanoparticle-based conductive elastomer. Taking advantage of the synergistic effects of silver trifluoroacetate and methanol, the swelling capability of an elastomeric block copolymer polystyrene-block-polyisoprene-block-polystyrene (SIS) was greatly enhanced. The interaction of silver ions and double bonds of the copolymer enables fast infiltration of soluble salt into the polymer network, resulting in a high-content loading of silver ions, which is a prerequisite for fabrication of a highly conductive polymer. In-situ reduction was performed under a swollen state to allow the reducer to effectively penetrate into the polymer matrix, thoroughly reducing the silver salt into silver nanoparticles. A three-layered conductive elastomer was obtained, with a high concentration of silver nanoparticles formed on both surfaces of SIS copolymer. Typically, the conductivity of the reduced SIS elastomer was measured to be >2 × 105 S/m when ε = 0, and can maintain to be over one seventh of its initial value even at a 200% elongation. The conductive elastomer can withstand over 1000 stretch-release cycles under a strain of 100%. A radio-frequency antenna was prepared with the conductive elastomer, which gives the ability of dimension tuning, to realize high-quality frequency-selective radiation at a wide bandwidth of larger than 2.6 GHz. Keywords: Matrix swelling, Silver nanoparticles, Elastomeric conductor, Flexible and stretchable electronics, Stretchable antenna

This paper presents a novel planar phased array that can work in Ka band designed for two-dimensional scanning. A four-modes pattern reconfigurable element based on microstrip Yagi antenna is proposed, and then developed into the 4X4 phased array, in which two feed points are introduced to reduce sidelobe level (SLL). The simulated results show that our proposed phased array is able to cover the scanning range from -60{\deg} to +60{\deg}in H-plane(yoz-plane) and -47.2{\deg}to +47.2{\deg}in E-plane(xoz-plane) with the gain reduction less than 3dB, both the SLLs of which are 10dB less than main beam. The two-dimensional scanning phased array based on pattern reconfigurable antenna (PRA) presented here is suitable for the satellite communication., Comment: 4 pages, 6 figures

Two-dimensional (2D) materials generally have unusual physical and chemical properties owing to the confined electro-strong interaction in a plane and can exhibit obvious anisotropy and a significant quantum-confinement effect, thus showing great promise in many fields. Some 2D materials, such as graphene and MXenes, have recently exhibited extraordinary electromagnetic-wave shielding and absorbing performance, which is attributed to their special electrical behavior, large specific surface area, and low mass density. Compared with traditional microwave attenuating materials, 2D materials have several obvious inherent advantages. First, similar to other nanomaterials, 2D materials have a very large specific surface area and can provide numerous interfaces for the enhanced interfacial polarization as well as the reflection and scattering of electromagnetic waves. Second, 2D materials have a particular 2D morphology with ultrasmall thickness, which is not only beneficial for the penetration and dissipation of electromagnetic waves through the 2D nanosheets, giving rise to multiple reflections and the dissipation of electromagnetic energy, but is also conducive to the design and fabrication of various well-defined structures, such as layer-by-layer assemblies, core–shell particles, and porous foam, for broadband attenuation of electromagnetic waves. Third, owing to their good processability, 2D materials can be integrated into various multifunctional composites for multimode attenuation of electromagnetic energy. In addition to behaving as microwave reflectors and absorbers, 2D materials can act as impedance regulators and provide structural support for good impedance matching and setup of the optimal structure. Numerous studies indicate that 2D materials are among the most promising microwave attenuation materials. In view of the rapid development and enormous advancement of 2D materials in shielding and absorbing electromagnetic wave, there is a strong need to summarize the recent research results in this field for presenting a comprehensive view and providing helpful suggestions for future development.

In order to achieve high gain in the azimuth to cover 360-degree range., a distributed multi-beam antenna based on switch transformation technique is proposed. Each antenna can cover 45-degree range in the direction of azimuth (eight antennas cover 360 degree) and 30 degree in the direction of elevation., respectively. The light weight and low cost Aperture Coupled Microstrip Antenna (ACMSA) is designed to broaden the bandwidth of the traditional microstrip antenna. The CST MWS is used to simulate and optimize the antenna element. Based on the designed antenna element., an array antenna is introduced. The array antenna prototype is fabricated using PCB processing technique and the measurement for the array is conducted., the measured results show a good agreement with the simulation where the gain of the antenna is about 10.7dBi and the S11 parameter of the antenna is less than −10dB in the frequency range, respectively. 8 array antennas are assembled upon aluminum sustain structure to cover 360 degrees in the direction of azimuth and each array antenna can be selected by the switch to realize communication.

A novel localization technique of printed chipless RFID in 3-D space is presented by using a frequency domain chipless tag. The chipless tag is interrogated by an ultra-wideband (UWB) signal, and the response from tag is analyzed for extracting the resonance information. The range information is used for accurate localization of chipless tag. The validity and accuracy of the localization method has been verified by moving the tag to different points in a fixed interrogation zone. The measured angular deviations achieved based on the proposed approach are less than 5 $^{\circ}$ when localization radius is from 10 cm to 40 cm.

This paper presents an analytical solution for capacitance and characteristic impedance of CPW with defected structures (CPW DS) in signal line. The first category of incomplete elliptic integrals F (φ, k) is employed for calculation, and the capacitance and characteristic impedance of CPW GS in signal line are first time achieved by the analytical solution. FEM simulation results are used to verify the results of analytical solution, which shows a good agreement. All calculations are completed in software Wolfram Mathematica, and CPW structures are simulated in software HFSS.

One of the two branches of the α-linolenic acid metabolism pathway is catalyzed by 12-oxo-phytodienoic acid reductase I, and the other is involved in jasmonic acid (JA) synthesis. The former is known to be active in the response to salinity tolerance in wheat (Triticum aestivum), but the participation of the latter in this response has not been established as yet. Here, the salinity-responsive bread wheat gene TaAOC1, which encodes an allene oxide cyclase involved in the α-linolenic acid metabolism pathway, was constitutively expressed in both bread wheat and Arabidopsis (Arabidopsis thaliana). In both species, transgenic lines exhibited an enhanced level of tolerance to salinity. The transgenic plants accumulated a higher content of JA and developed shorter roots. Both the shortened roots and the salinity tolerance were abolished in a background lacking a functional AtMYC2, a key component of the JA and abscisic acid signaling pathway, but were still expressed in a background deficient with respect to abscisic acid synthesis. We provide the first evidence, to our knowledge, suggesting that JA is also involved in the plant salinity response and that the α-linolenic acid metabolism pathway has a regulatory role over this response.

This paper presents a coplanar waveguide (CPW) tunable band-stop filter using hybrid resonator and employing RF microelectromechanical systems (MEMS) capacitors. The MEMS switches are used as varactors to tune the filter resonance frequency. Defected ground structures (DGSs) with MEMS switch is employed for filter unit to achieve miniaturization of filter structure. To accurately analyze the filter unit structure parameters, a hybrid resonance circuit is used as equivalent circuit and the relationship of MEMS switch and the transverse slot capacitance is analyzed. Hereby, a CPW tunable band-stop filter, cascaded periodically by DGS and MEMS switches, is fabricated on a glass substrate (er=3.78,tan δ = 0.0012). The filter has a midband retune loss of 2.3-2.8 dB and a tuning range of 35% from 8.5 to 12.3 GHz with a maximum dc voltage of 44 V. Finally, we propose a solution to achieve constant bandwidth when center frequency changes.

For miniaturization the microwave communication equipment, a miniaturized and low cost array antenna is proposed. A 2-layer of patch antenna unit is designed to broaden the bandwidth of the microstrip antenna. The CST MWS is used to simulate and optimize the antenna structure. Based on the designed antenna unit, an array antenna is proposed to achieve high gain, and the simulation and optimization are conducted. The array antenna prototype is fabricated on dielectric substrate by using PCB processing technic based on the simulation results. And the measurement for the array antenna is carried out, the measured results can be coincide with the simulation, the gain of the antenna is about 27dBi, and the S11 parameter of the antenna is less than 𢀒10dB in the frequency range.

The terahertz wave source plays an important role in high rate indoor communication. There are two techniques to radiate the terahertz wave, electronic and photonic techniques. According to the environment of terahertz indoor wireless communication, some good choices of THz source devices are proposed, such as mixer, resonant tunneling oscillator and THz-over-Fiber technique. The latest research results of our work are given in detail.

Electromagnetic metamaterials offer great flexibility for wave manipulation and enable exceptional functionality design, ranging from negative refraction, anomalous reflection, super-resolution imaging, transformation optics to cloaking, etc. However, demonstration of metamaterials with unprecedented functionalities is still challenging and costly due to the structural complexity or special material properties. Here, we demonstrate for the first time the versatile fluidic radio frequency metamaterials with negative refraction using a water-embedded and metal-coated 3D architecture. Effective medium analysis confirms that metallic frames create an evanescent environment while simultaneously water cylinders produce negative permeability under Mie resonance. The water-metal coupled 3D architectures and the accessory devices for measurement are fabricated by 3D printing with post electroless deposition. Our study also reveals the great potential of fluidic metamaterials and versatility of the 3D printing proc...

This letter presents an RF microelectromechanical systems (MEMS) tunable bandpass filter with a tuning range of 30%. An analytical process of designing a bandpass filter is also presented by using MEMS switch, series gap, and etched structure in coplanar waveguide (CPW). The designed structure of the MEMS switch and CPW is used to get a wide tuning range of the filter. The fabricated filter performances show an acceptable agreement between the measured results and the simulation results with a center frequency from 10 to 13.5 GHz.

A novel band-pass filter using a dual-mode resonator is presented with a excellent performance. The effect of out/input coupling structures arranged at 1800 geometrically is discussed for the dual-mode filter. The coupling coefficient between degenerate modes of dual-mode resonator is investigated by the perturbation size. The dual-mode band-pass filter is designed, fabricated and measured. The filter is designed and implemented at 2.8 GHz with 10.5% bandwidth, and the performances show a low passband insertion loss of 0.7 dB with good harmonics inhibited and the rejection better than 25 dB from about 3 GHz.

A C-band 2×2 microstrip quasi-Yagi antenna array has been designed to meet the requirement of small volume and light weight antenna of a C-band microwave communication system. The simulation and optimization for the antenna unit were conducted and the structure parameters were extracted. The fabrication and test for the 1×2 microstrip quasi-Yagi antenna array were implemented on the bases of simulation. The results of simulation and test can coincide with each other, and the return loss is less than −10 dB in the range of 4 to 5 GHz. The simulation for the 2×2 antenna array has been carried out basing on the test of 1 ×2 antenna array, and the simulated gain of the antenna array is more than 13 dB, the return loss is less than −10 dB in the frequency range of requirement.

Recent evidence suggests that many endogenous circular RNAs (circRNAs) may play roles in biological processes. However, the expression patterns and functions of circRNAs in human diseases are not well understood. Computationally identifying circRNAs from total RNA-seq data is a primary step in studying their expression pattern and biological roles. In this work, we have developed a computational pipeline named UROBORUS to detect circRNAs in total RNA-seq data. By applying UROBORUS to RNA-seq data from 46 gliomas and normal brain samples, we detected thousands of circRNAs supported by at least two read counts, followed by successful experimental validation on 24 circRNAs from the randomly selected 27 circRNAs. UROBORUS is an efficient tool that can detect circRNAs with low expression levels in total RNA-seq without RNase R treatment. The circRNAs expression profiling revealed more than 476 circular RNAs differentially expressed in control brain tissues and gliomas. Together with parental gene expression, we found that circRNA and its parental gene have diversified expression patterns in gliomas and control brain tissues. This study establishes an efficient and sensitive approach for predicting circRNAs using total RNA-seq data. The UROBORUS pipeline can be accessed freely for non-commercial purposes at http://uroborus.openbioinformatics.org/.

There is an increasing demand for flexible electronics and optoelectronic devices, which requires designing and developing electronic devices on flexible substrates. Realization of flexible electronics with comparable or equal performance to conventional silicon-based microelectronics could enable a significant amount of new applications. Digital printing technologies have achieved great success on depositing functional materials to form patterns on flexible substrate, which is essential for flexible electronics development. In this review, we first summrize the unique advantage of digital printing technology over conventional microelectronics and other non-digital based printing methods, like screen printing. Then this article reviews the research and development of digital printing technology for fabriction electronic devices on flexible substrates. Firstly, the printing materials, including conductive materials, semiconductor materials and insulatiing materials, are throughly discussed and different flexible substrates are also reviewed. Then, from reviewing different digital printing techniques, the challenges of implementing flexible electronics into practical application are discussed. Three typical digital printing techniques are discussed, including inkjet printing, electrohydrodynamic printing and aerosol jet printing. Both the limitation and the advantage of digital printing techniques are discussed. One of the major advantages of digital printing is their ability of incorporating the processes into R2R manufacturing process, which is critial for both industry and consumer products, and eliminates the limitation of prototyping application. Thirdly, the related applications of digital printing on the flexible electronic devices are shown. In this review, the key technologies and application of flexible electronics are analyzed, different materials and digital printing technologies, and their applications in 2D/3D printed electronics are shown. Although flexible electronics has achieved great success, the challenges still remain. At the end, some opinions about the development of flexible electronics are raised. The flexiblity, functionality and durablity of flexible electronics still need to be improved in order to provide more practical products into the market.