High-speed railway (HSR) brings convenience to peoples' lives and is generally considered as one of the most sustainable developments for ground transportation. One of the important parts of HSR ...construction is the signaling system, which is also called the "operation control system," where wireless communications play a key role in the transmission of train control data. We discuss in detail the main differences in scientific research for wireless communications between the HSR operation scenarios and the conventional public land mobile scenarios. The latest research progress in wireless channel modeling in viaducts, cuttings, and tunnels scenarios are discussed. The characteristics of nonstationary channel and the line-of-sight (LOS) sparse and LOS multiple-input-multiple-output channels, which are the typical channels in HSR scenarios, are analyzed. Some novel concepts such as composite transportation and key challenging techniques such as train-to-train communication, vacuum maglev train techniques, the security for HSR, and the fifth-generation wireless communications related techniques for future HSR development for safer, more comfortable, and more secure HSR operation are also discussed.
Since the outbreak of severe acute respiratory syndrome (SARS) 18 years ago, a large number of SARS-related coronaviruses (SARSr-CoVs) have been discovered in their natural reservoir host, bats
. ...Previous studies have shown that some bat SARSr-CoVs have the potential to infect humans
. Here we report the identification and characterization of a new coronavirus (2019-nCoV), which caused an epidemic of acute respiratory syndrome in humans in Wuhan, China. The epidemic, which started on 12 December 2019, had caused 2,794 laboratory-confirmed infections including 80 deaths by 26 January 2020. Full-length genome sequences were obtained from five patients at an early stage of the outbreak. The sequences are almost identical and share 79.6% sequence identity to SARS-CoV. Furthermore, we show that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus. Pairwise protein sequence analysis of seven conserved non-structural proteins domains show that this virus belongs to the species of SARSr-CoV. In addition, 2019-nCoV virus isolated from the bronchoalveolar lavage fluid of a critically ill patient could be neutralized by sera from several patients. Notably, we confirmed that 2019-nCoV uses the same cell entry receptor-angiotensin converting enzyme II (ACE2)-as SARS-CoV.
COVID-19 has spread worldwide since 2019 and is now a severe threat to public health. We previously identified the causative agent as a novel SARS-related coronavirus (SARS-CoV-2) that uses human ...angiotensin-converting enzyme 2 (hACE2) as the entry receptor. Here, we successfully developed a SARS-CoV-2 hACE2 transgenic mouse (HFH4-hACE2 in C3B6 mice) infection model. The infected mice generated typical interstitial pneumonia and pathology that were similar to those of COVID-19 patients. Viral quantification revealed the lungs as the major site of infection, although viral RNA could also be found in the eye, heart, and brain in some mice. Virus identical to SARS-CoV-2 in full-genome sequences was isolated from the infected lung and brain tissues. Last, we showed that pre-exposure to SARS-CoV-2 could protect mice from severe pneumonia. Our results show that the hACE2 mouse would be a valuable tool for testing potential vaccines and therapeutics.
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•SARS-CoV-2 could infect HFH4-hACE2 mice and cause death•SARS-CoV-2 infection localizes to lungs of mice and causes typical interstitial pneumonia•Pre-exposure to SARS-CoV-2 protects mice from lethal challenge
A SARS-CoV-2 hACE2 transgenic mouse infection model recapitulates a number of infection symptoms and pathology in COVID-19 patients. Pre-exposure to SARS-CoV-2 was able to protect mice from severe pneumonia.
Single-atom catalysts (SACs) exhibit intriguing catalytic performance owing to their maximized atom utilizations and unique electronic structures. However, the reported strategies for synthesizing ...SACs generally have special requirements for either the anchored metals or the supports. Herein, we report a universal approach of electrochemical deposition that is applicable to a wide range of metals and supports for the fabrication of SACs. The depositions were conducted on both cathode and anode, where the different redox reactions endowed the SACs with distinct electronic states. The SACs from cathodic deposition exhibited high activities towards hydrogen evolution reaction, while those from anodic deposition were highly active towards oxygen evolution reaction. When cathodically- and anodically-deposited Ir single atoms on Co
Fe
Se
@Ni foam were integrated into a two-electrode cell for overall water splitting, a voltage of 1.39 V was required at 10 mA cm
in alkaline electrolyte.
Abstract
Sn-based compounds with buffer matrixes possessing high theoretical capacity, low working voltage, and alleviation of the volume expansion of Sn are ideal materials for lithium storage. ...However, it is challenging to confine well-dispersed Sn within a lithium active matrix because low-melting-point Sn tends to agglomerate. Here, we apply a metal-organic framework (MOF) chemistry between Sn-nodes and lithium active ligands to create two Sn-based MOFs comprising Sn
2
(dobdc) and Sn
2
(dobpdc) with extended ligands from H
4
dobdc (2,5-dioxido-1,4-benzenedicarboxylate acid) to H
4
dobpdc (4,4’-dioxidobiphenyl-3,3’-dicarboxylate acid) with molecule-level homodispersion of Sn in organic matrixes for lithium storage. The enhanced utilization of active sites and reaction kinetics are achieved by the isoreticular expansion of the organic linkers. The reversible formation of coordination bonds during lithium storage processes is revealed by X-ray absorption fine structure characterization, providing an in-depth understanding of the lithium storage mechanism in coordination compounds.
Topological acoustics has recently revolutionized fundamental concepts of acoustic propagation, giving rise to strikingly unique acoustic edge modes immune to backscattering. Despite the rapid ...progress in this field, simultaneous realization of reconfigurability, intelligentization, and automatic control over acoustic propagation paths is posing a great challenge. This challenge is overcome by proposing the concept of a programmable acoustic topological insulator based on two digital elements “0” or “1,” which consist of honeycomb‐lattice sonic crystals made of cylindrical rods with different diameters. The acoustic propagation paths in the topological insulators can be controlled automatically by programming different coding sequences, which arises from efficient transformation of pseudospin‐dependent edge modes on both interfaces of the digital elements. More importantly, a unique unit is experimentally fabricated that has either a “0” or “1” response automatically manipulated by an air cylinder, and design topological insulators with programmable functionality, to realize three digital acoustic devices, such as a single‐pole double‐throw switch, a single‐pole single‐throw switch, and a tunable logic gate. The proposed programmable topological insulators may enable future intelligent acoustic devices with exciting reconfigurable and programmable functionalities, which may lead to important advances in various applications, such as integrated acoustics, acoustic security, and information processing.
Programmable acoustic topological insulators (ATIs) enable future intelligent acoustic devices with reconfigurable and programmable functionalities. A unique unit of ATI with either “0” or “1” response automatically manipulated by an air cylinder is fabricated. By programming coding sequences of ATIs, three digital acoustic devices, including a single‐pole double‐throw switch, a single‐pole single‐throw switch, and a tunable logic gate, are demonstrated experimentally.
Background
Systemic lupus erythematosis (SLE) is a complex and clinically heterogeneous autoimmune disease. A variety of immunological defects contribute to SLE, including dysregulated innate and ...adaptive immune response. A clearer understanding of the mechanisms driving disease pathogenesis combined with recent advances in medical science is predicted to enable accelerated progress towards improved SLE-personalized approaches to treatment. The aim of this review was to clarify the immunological pathogenesis and treatment of SLE.
Data sources
Literature reviews and original research articles were collected from database, including PubMed and Wanfang. Relevant articles about SLE were included.
Results
Breakdown of self-tolerance is the main pathogenesis of SLE. The innate and adaptive immune networks are interlinked with each other through cytokines, complements, immune complexes and kinases of the intracellular machinery. Treatments targeted at possible targets of immunity have been assessed in clinical trials. Most of them did not show better safety and efficacy than traditional treatments. However, novel targeting treatments are still being explored.
Conclusions
Dysregulated immune response plays a critical role in SLE, including innate immunity and adaptive immunity. Biologic agents that aim to specifically target abnormal immune processes were assessing and may bring new hope to SLE patients.
2D materials hold great potential for designing novel electronic and optoelectronic devices. However, 2D material can only absorb limited incident light. As a representative 2D semiconductor, ...monolayer MoS2 can only absorb up to 10% of the incident light in the visible, which is not sufficient to achieve a high optical‐to‐electrical conversion efficiency. To overcome this shortcoming, a “gap‐mode” plasmon‐enhanced monolayer MoS2 fluorescent emitter and photodetector is designed by squeezing the light‐field into Ag shell‐isolated nanoparticles–Au film gap, where the confined electromagnetic field can interact with monolayer MoS2. With this gap‐mode plasmon‐enhanced configuration, a 110‐fold enhancement of photoluminescence intensity is achieved, exceeding values reached by other plasmon‐enhanced MoS2 fluorescent emitters. In addition, a gap‐mode plasmon‐enhanced monolayer MoS2 photodetector with an 880% enhancement in photocurrent and a responsivity of 287.5 A W−1 is demonstrated, exceeding previously reported plasmon‐enhanced monolayer MoS2 photodetectors.
By dropping Ag shell‐isolated nanoparticles onto Al2O3‐covered Au film, the gap‐mode plasmonic structure with a gap thickness of 7 nm can form naturally. By integrating monolayer MoS2 into this plasmonic structure, 110‐fold photoluminescence and 880% photocurrent enhancement are achieved. This work shows that the gap‐mode plasmonic structures have huge potential for realizing high‐performance 2D‐material‐based optoelectronic devices.
Abstract
Supported gold (Au) nanocatalysts have attracted extensive interests in the past decades because of their unique catalytic properties for a number of key chemical reactions, especially in ...(selective) oxidations. The activation of O
2
on Au nanocatalysts is crucial and remains a challenge because only small Au nanoparticles (NPs) can effectively activate O
2
. This severely limits their practical application because Au NPs inevitably sinter into larger ones during reaction due to their low Taman temperature. Here we construct a Au-SiO
2
interface by depositing thin SiO
2
layer onto Au/TiO
2
and calcination at high temperatures and demonstrate that the interface can be not only highly sintering resistant but also extremely active for O
2
activation. This work provides insights into the catalysis of Au nanocatalysts and paves a way for the design and development of highly active supported Au catalysts with excellent thermal stability.
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