In comparison to severe acute respiratory syndrome coronavirus (SARS-CoV), SARS-CoV-2 appears to be more contagious 1, and coronavirus disease 2019 (COVID-19) patients demonstrate varied clinical ...manifestations distinct from those seen in patients with SARS-CoV and Middle East respiratory syndrome coronavirus infections 2. Collective results from the clinical and epidemiological observations suggest a distinct viral–host interaction in COVID-19 patients. Profiling of the antibody response during SARS-CoV-2 infection may help improve our understanding of the viral–host interaction and the immunopathological mechanisms of the disease.
Humoral immune response to SARS-CoV-2 showed an early response of IgA, instead of IgM, in COVID-19 patients. As highlighted by this study, enhanced IgA responses observed in severe COVID-19 might confer damaging effects in severe COVID-19.
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Abstract
Dielectric capacitors with high energy storage performance are highly desired for next-generation advanced high/pulsed power capacitors that demand miniaturization and integration. However, ...the poor energy-storage density that results from the low breakdown strength, has been the major challenge for practical applications of dielectric capacitors. Herein, we propose a heterovalent-doping-enabled atom-displacement fluctuation strategy for the design of low-atom-displacements regions in the antiferroelectric matrix to achieve the increase in breakdown strength and enhancement of the energy-storage density for AgNbO
3
-based multilayer capacitors. An ultrahigh breakdown strength ~1450 kV·cm
−1
is realized in the Sm
0.05
Ag
0.85
Nb
0.7
Ta
0.3
O
3
multilayer capacitors, especially with an ultrahigh U
rec
~14 J·cm
−3
, excellent η ~ 85% and P
D,max
~ 102.84 MW·cm
−3
, manifesting a breakthrough in the comprehensive energy storage performance for lead-free antiferroelectric capacitors. This work offers a good paradigm for improving the energy storage properties of antiferroelectric multilayer capacitors to meet the demanding requirements of advanced energy storage applications.
Carbon-based materials, as one of the most important electrode materials for supercapacitors, have attracted tremendous attention. At present, it is highly desirable but remains challenging to ...prepare one-dimensional carbon complex hollow nanomaterials for further improving the performance of supercapacitors. Herein, we report an effective strategy for the synthesis of hollow particle-based nitrogen-doped carbon nanofibers (HPCNFs-N). By embedding ultrafine zeolitic imidazolate framework (ZIF-8) nanoparticles into electrospun polyacrylonitrile (PAN), the as-prepared composite nanofibers are carbonized into hierarchical porous nanofibers composed of interconnected nitrogen-doped carbon hollow nanoparticles. Owing to its unique structural feature and the desirable chemical composition, the derived HPCNFs-N material exhibits much enhanced electrochemical properties as an electrode material for supercapacitors with remarkable specific capacitance at various current densities, high energy/power density and long cycling stability over 10 000 cycles.
Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which ...QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD-a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.
The ongoing coronavirus disease 2019 (COVID-19) pandemic has prioritized the development of small-animal models for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We adapted a clinical ...isolate of SARS-CoV-2 by serial passaging in the respiratory tract of aged BALB/c mice. The resulting mouse-adapted strain at passage 6 (called MASCp6) showed increased infectivity in mouse lung and led to interstitial pneumonia and inflammatory responses in both young and aged mice after intranasal inoculation. Deep sequencing revealed a panel of adaptive mutations potentially associated with the increased virulence. In particular, the N501Y mutation is located at the receptor binding domain (RBD) of the spike protein. The protective efficacy of a recombinant RBD vaccine candidate was validated by using this model. Thus, this mouse-adapted strain and associated challenge model should be of value in evaluating vaccines and antivirals against SARS-CoV-2.
Solid/liquid interfaces are ubiquitous in nature and knowledge of their atomic-level structure is essential in elucidating many phenomena in chemistry, physics, materials science and Earth science
. ...In electrochemistry, in particular, the detailed structure of interfacial water, such as the orientation and hydrogen-bonding network in electric double layers under bias potentials, has a significant impact on the electrochemical performances of electrode materials
. To elucidate the structures of electric double layers at electrochemical interfaces, we combine in situ Raman spectroscopy and ab initio molecular dynamics and distinguish two structural transitions of interfacial water at electrified Au single-crystal electrode surfaces. Towards negative potentials, the interfacial water molecules evolve from structurally 'parallel' to 'one-H-down' and then to 'two-H-down'. Concurrently, the number of hydrogen bonds in the interfacial water also undergoes two transitions. Our findings shed light on the fundamental understanding of electric double layers and electrochemical processes at the interfaces.
Recently, heteroatom‐doped three‐dimensional (3D) nanostructured carbon materials have attracted immense interest because of their great potential in various applications. Hence, it is highly ...desirable to exploit a simple, renewable, scalable, multifunctional, and general strategy to engineer 3D heteroatom‐doped carbon nanomaterials. Herein, a simple, eco‐friendly, general, and effective way to fabricate 3D heteroatom‐doped carbon nanofiber networks on a large scale is reported. Using this method, 3D P‐doped, N,P‐co‐doped, and B,P‐co‐doped carbon nanofiber networks are successfully fabricated by the pyrolysis of bacterial cellulose immersed in H3PO4, NH4H2PO4, and H3BO3/H3PO4 aqueous solution, respectively. Moreover, the as‐prepared N,P‐co‐doped carbon nanofibers exhibit good supercapacitive performance.
A simple, efficient, and general approach is developed for preparing cost‐effective, three‐dimensional, and large‐scale heteroatom‐doped carbon nanofibers, such as P‐doped, N,P‐co‐doped, and B,P‐co‐doped carbon nanofibers, by pyrolyzing bacterial cellulose (BC) previously immersed in H3PO4, NH4H2PO4, and H3BO3/H3PO4, respectively. Moreover, the as‐prepared N,P‐co‐doped carbon nanofibers exhibit good supercapacitive performance.
Thermoelectric technology enables the harvest of waste heat and its direct conversion into electricity. The conversion efficiency is determined by the materials figure of merit
Here we show a maximum
...of ~2.8 ± 0.5 at 773 kelvin in n-type tin selenide (SnSe) crystals out of plane. The thermal conductivity in layered SnSe crystals is the lowest in the out-of-plane direction two-dimensional (2D) phonon transport. We doped SnSe with bromine to make n-type SnSe crystals with the overlapping interlayer charge density (3D charge transport). A continuous phase transition increases the symmetry and diverges two converged conduction bands. These two factors improve carrier mobility, while preserving a large Seebeck coefficient. Our findings can be applied in 2D layered materials and provide a new strategy to enhance out-of-plane electrical transport properties without degrading thermal properties.
Exploring low‐cost and high‐performance nonprecious metal catalysts (NPMCs) for oxygen reduction reaction (ORR) in fuel cells and metal–air batteries is crucial for the commercialization of these ...energy conversion and storage devices. Here we report a novel NPMC consisting of Fe3C nanoparticles encapsulated in mesoporous Fe‐N‐doped carbon nanofibers, which is synthesized by a cost‐effective method using carbonaceous nanofibers, pyrrole, and FeCl3 as precursors. The electrocatalyst exhibits outstanding ORR activity (onset potential of −0.02 V and half‐wave potential of −0.140 V) closely comparable to the state‐of‐the‐art Pt/C catalyst in alkaline media, and good ORR activity in acidic media, which is among the highest reported activities of NPMCs.
Nanocomposite electrocatalyst: A high‐performance electrocatalyst for the oxygen reduction reaction (ORR) is based on Fe3C nanoparticles encapsulated in mesoporous Fe‐N‐doped carbon nanofibers. It can be synthesized from low‐cost and abundant precursors and exhibits excellent electrocatalytic performance for the ORR in both alkaline and acidic media.
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