Massive multiple-input multiple-output (M-MIMO) technology is considered to be a key enabling technology for future wireless communication systems. One of the challenges in effectively implementing ...an advanced precoding scheme to a large-scale array antenna is how to reduce the mutual coupling among antenna elements. In this paper, a new concept that is called array-antenna decoupling surface (ADS) for reducing the mutual coupling between antenna elements in a large-scale array antenna is proposed for the first time. An ADS is a thin surface that is composed of a plurality of electrical small metal patches and is placed in front of the array antenna. The partially diffracted waves from the ADS can be controlled to cancel the unwanted coupled waves. Two practical design examples are given to illustrate the design process and considerations, and to demonstrate the usefulness of ADS for the applications of phased array antennas and M-MIMO systems when commonly used precoding schemes are applied. The attractive features of ADS include its applicability to a large-scale array antenna; suitability for a wide range of antenna forms; wide decoupling bandwidth; and simplicity in implementation.
Plant-pathogen interactions induce a signal transmission series that stimulates the plant's host defense system against pathogens and this, in turn, leads to disease resistance responses. Plant ...innate immunity mainly includes two lines of the defense system, called pathogen-associated molecular pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). There is extensive signal exchange and recognition in the process of triggering the plant immune signaling network. Plant messenger signaling molecules, such as calcium ions, reactive oxygen species, and nitric oxide, and plant hormone signaling molecules, such as salicylic acid, jasmonic acid, and ethylene, play key roles in inducing plant defense responses. In addition, heterotrimeric G proteins, the mitogen-activated protein kinase cascade, and non-coding RNAs (ncRNAs) play important roles in regulating disease resistance and the defense signal transduction network. This paper summarizes the status and progress in plant disease resistance and disease resistance signal transduction pathway research in recent years; discusses the complexities of, and interactions among, defense signal pathways; and forecasts future research prospects to provide new ideas for the prevention and control of plant diseases.
There is an emerging need for semiconductors that can be processed at near ambient temperature with high mobility and device performance. Although multiple n-type options have been identified, the ...development of their p-type counterparts remains limited. Here, we report the realization of tellurium thin films through thermal evaporation at cryogenic temperatures for fabrication of high-performance wafer-scale p-type field-effect transistors. We achieve an effective hole mobility of ~35 cm
V
s
, on/off current ratio of ~10
and subthreshold swing of 108 mV dec
on an 8-nm-thick film. High-performance tellurium p-type field-effect transistors are fabricated on a wide range of substrates including glass and plastic, further demonstrating the broad applicability of this material. Significantly, three-dimensional circuits are demonstrated by integrating multi-layered transistors on a single chip using sequential lithography, deposition and lift-off processes. Finally, various functional logic gates and circuits are demonstrated.
Staggered array antenna is a common array configuration for large-scale array antennas due to its favorable radiation characteristics and relatively large element spacing. In developing a compact ...staggered dipole array, the most challenging issue is how to simultaneously reduce the four mutual couplings taking place between adjacent co-polarized antenna elements with diversified phase laggings. A large difference in the phase of different mutual couplings makes simultaneous reduction of all the mutual couplings by applying the recently developed array-antenna decoupling surface (ADS) technique difficult. In this article, a phase compensation method by using a staple-shaped probe for alleviating the largest phase offset is proposed conceptually and verified experimentally. With the proposed phase compensation method, the ADS technique can be effectively applied to a compact staggered dipole array with a wideband simultaneous decoupling. The design guideline for the phase compensation probe is presented by EM simulation and a parametric study. Two practical design examples of dual polarized staggered dipole arrays are given to demonstrate the effectiveness of the proposed phase compensation method in conjunction with ADS, showing a promising potential for wideband simultaneous decoupling of a large-scale dual polarized staggered dipole array-antenna.
A new wideband ±45° dual-polarized metal loop dielectric resonator magnetoelectric antenna is proposed in this communication. The antenna consists of two orthogonal dielectric bars that support two ...orthogonal electric dipoles and two cross interlaced metal semi-loops that are equivalent to two orthogonal magnetic dipoles above the ground. With a legitimate combination of the electric and magnetic dipoles, a unidirectional radiation with low backward radiation and equal E-plane and H-plane radiation patterns can be achieved. The antenna can be made of a monolithic dielectric block with simple installation. To validate the new antenna configuration, a prototype is designed, manufactured, and measured. The prototype antenna using ceramic with the electrical size of <inline-formula> <tex-math notation="LaTeX">0.33\lambda _{o} \times 0.33\lambda _{o} \times 0.21\lambda _{o} </tex-math></inline-formula> demonstrates that an impedance bandwidth of 11.4% (<inline-formula> <tex-math notation="LaTeX">\vert S_{11}\vert < -15 </tex-math></inline-formula> dB) in the 3.5 GHz frequency band can be achieved with the measured forward/backward ratio of better than 22 dB. The proposed antenna is suitable as antenna element for massive-MIMO array antennas, where a large number of antenna elements need to be installed in a compact space.
Performance declination of nanofiltration (NF) membranes caused by concentration polarization (CP) and membrane fouling has severely restricted their practical application in many fields. This work ...reports the construction of a novel interlayer between the substrate and the selective layer of conventional composite membranes by coordinating regulation of carbon quantum dots (CQDs) and polydopamine (PDA). Unlike traditional methods that treat CP and fouling separately, the new strategy grants the membrane with dual functions at one time. First, the insertion of the PDA–CQDs layer reformulates the interfacial polymerization process that reduces the solute transport resistance and mitigates the CP issue. Second, the sandwiched photoactive CQDs can degrade organic molecules adsorbed on the membrane surface under visible light, which is promising for low-cost fouling remediation. This study may offer valuable insights into the preparation of durable self-cleaning NF membranes for the effective treatment of complex wastewater in various industries.
The fates of cadmium (Cd) and arsenic (As) in paddy fields are generally opposite; thus, the inconsistent transformation of Cd and As poses large challenges for their remediation. In this study, the ...impacts of zero valent iron (ZVI) and/or biochar amendments on Cd and As bioavailability were examined in pot trials with rice. Comparison with the untreated soil, both Cd and As accumulation in different rice tissues decreased significantly in the ZVI-biochar amendments and the Cd and As accumulation in rice decreased with increasing ZVI contents. In particular, the concentrations of Cd (0.15 ± 0.01 mg kg−1) and As (0.17 ± 0.01 mg kg−1) in rice grains were decreased by 93% and 61% relative to the untreated soil, respectively. A sequential extraction analysis indicated that with increasing Fe ratios in the ZVI-biochar mixtures, bioavailable Cd and As decreased, and the immobilized Cd and As increased. Furthermore, high levels of Fe, Cd, and As were detected in Fe plaque of the ZVI-biochar amendments in comparison with the single biochar or single ZVI amendments. The ZVI-biochar mixture may have a synergistic effect that simultaneously reduces Cd and As bioavailability by increasing the formation of amorphous Fe and Fe plaque for Cd and As immobilization. The single ZVI amendment significantly decreased As bioavailability, while the single biochar amendment significantly reduced the bioavailability of Cd compared with the combined amendments. Hence, using a ZVI-biochar mixture as a soil amendment could be a promising strategy for safely-utilizing Cd and As co-contaminated sites in the future.
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•The single zero valent iron amendment decreased the bioavailability of As.•The single biochar amendment reduced the bioavailability of Cd.•The ZVI-biochar amendments simultaneously reduced Cd and As bioavailability.•The Fe, Cd, and As in plaque increased significantly in the ZVI-biochar amendments.•The ZVI-biochar amendments increased the amorphous Fe oxides in soils.
•A kind of acidic polysaccharide was isolated from Annona squamosa.•Three different methods were used to determine the monosaccharide composition.•Methylation, FT-IR and NMR were combined to ...characterize the structure.•The acidic polysaccharide had a certain inhibition activity on α-glucosidase.
The crude polysaccharide (TASP3) was extracted from the fruit pulp of Annona squamosa and then isolated and purified by the combination of grading-alcoholic precipitation and Sephadex G-200. The structure of purified polysaccharide (GASP3-3-I) was determined based on the physicochemical and instrumental analyses. The results indicated that GASP3-3-I was an acidic heteropolysaccharide and its average molecular weight was 2.28×106Da. The monosaccharide composition was analysed by GC–MS and ion chromatography, respectively. It was revealed that GASP3-3-I was consisted of rhamnose, arabinose, xylose, mannose, glucose, galactose, glucuronic acid and galacturonic acid with a molar ratio of 5.06:45.5:5.26:0.63:6.09:31.76:0.49:5.19. Moreover, periodate oxidation reaction, Smith degrading reaction, methylation, FT-IR and NMR were used to conduct the structural characterization of GASP3-3-I. The results indicated that glycosyl residues of GASP3-3-I were mainly composed of (1→) l-arabinose, (1→6), (1→3) and (1,3→6) d-galactose, (1→) d-xylose, (3→) and (3→6) d-glucose, (1→2) l-rhamnose. The α-glucosidase inhibitory activity assay showed that GASP3-3-I had a certain inhibition on α-glucosidase activity.
Abstract
We revisit dark-matter production through freeze-in and
freeze-out by solving the Boltzmann equations at the level of the
phase-space distribution
f
(
p,t
). Using the 2 ⟶ 2 annihilation
and ...the 1 ⟶ 2 decay processes for illustration, we compare the
resulting dark-matter relic abundance with that from the
number-density approach. In the transition regime between freeze-in
and freeze-out, we find the difference can be quite significant, or
even by orders of magnitude if the annihilation of dark-matter
particles or the decaying mediator is neglected. The freeze-in
production in the 2 ⟶ 2 and the 1 ⟶ 2 processes can also result
in non-thermal phase-space distributions, or even multi-modal ones
with out-of-equilibrium decay, which can potentially affect
structure formation at late times. We also investigate how elastic
scatterings can distort such non-thermal distributions.
Six triterpenic acids were separated and purified from the ethyl acetate extractive fraction of ethanol extracts of Potentilla parvifolia FISCH. using a variety of chromatographic methods. The ...neuroprotective effects of these triterpenoids were investigated in the present study, in which the okadaic acid induced neurotoxicity in human neuroblastoma SH-SY5Y cells were used as an Alzheimer’s disease cell model in vitro. The cell model was established with all trans-retinoic acid (5 µmol/L, 4 d) and okadaic acid (40 nmol/L, 6 h) treatments to induce tau phosphorylation and synaptic atrophy. Subsequently, the neuroprotective effects of these triterpenic acids were evaluated in vitro by this cell model. Results from the Western blot and morphology analysis suggested that compounds 3–6 had the better neuroprotective effects. Furthermore, we tested the level of mitochondrial reactive oxygen species and mitochondrial membrane potential of these compounds in SH-SY5Y cells by flow cytometry technology to investigate the potential neuroprotective mechanism of these compounds. All of the results indicated that maybe the mechanism of compounds 5 and 6 is to protect the cell from mitochondrial oxidative stress injuries.
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