Showing papers by "Lei Wang published in 2020"

Rapid Detection of SARS-CoV-2 Using Reverse transcription RT-LAMP method

Abstract: Corona Virus Disease 2019 (COVID-19) is a recently emerged life-threatening disease caused by SARS-CoV-2. Real-time fluorescent PCR (RT-PCR) is the clinical standard for SARS-CoV-2 nucleic acid detection. To detect SARS-CoV-2 early and control the disease spreading on time, a faster and more convenient method for SARS-CoV-2 nucleic acid detecting, RT-LAMP method (reverse transcription loop-mediated isothermal amplification) was developed. RNA reverse transcription and nucleic acid amplification were performed in one step at 63 °C isothermal conditions, and the results can be obtained within 30 minutes. ORF1ab gene, E gene and N gene were detected at the same time. ORF1ab gene was very specific and N gene was very sensitivity, so they can guarantee both sensitivity and specificity for SARS-CoV-2. The sensitivity of RT-LAMP assay is similar to RT-PCR, and specificity was 99% as detecting 208 clinical specimens. The RT-LAMP assay reported here has the advantages of rapid amplification, simple operation, and easy detection, which is useful for the rapid and reliable clinical diagnosis of SARS-CoV-2.

HUBS: Hot Universe Baryon Surveyor

Abstract: Hot Universe Baryon Surveyor (HUBS) is proposed in China as a major X-ray mission for the next decade. It is designed to be highly focused scientifically, with two primary objectives: (1) detecting X-ray emission from hot baryons in intergalactic medium and circumgalactic medium (CGM), and characterizing their physical and chemical properties; (2) studying, based on the observations, the accretion and feedback processes that are thought to be highly relevant to the heating and chemical enrichment of the baryons in the CGM. Because of very low densities, the signal is expected to be very weak and thus technically difficult to detect. On the other hand, the spectrum of the emission is expected to be line rich, so it would be effective for detecting the hot baryons in bright emission lines. For that, an instrument with high spectral resolution, large effective area and large field of view (FoV) would be required. HUBS will couple a TES-based X-ray imaging spectrometer to a large FoV X-ray telescope to satisfy these requirements. A preliminary design of HUBS is presented.

Recent Advances in MXenes for Lithium-Ion Capacitors

Abstract: Recently, two-dimensional MXenes and MXene-based nanocomposites have become the most important electrode materials because of their unique physical and chemical characteristics. As the electrode of a lithium-ion capacitor, MXenes have exhibited metallic conductivity and plastic layer structure that provide more chemically active interfaces and shortened ion-diffusion lengths, and thus the unbalanced ion kinetics between the anode and cathode can be effectively alleviated. In order to further improve the electrochemical performance of MXenes, the composition, morphology and texture, surface chemistry, and structural configuration of MXenes are extensively investigated. In this mini-review, some recent research and progress of MXenes and MXene-based nanocomposites in lithium-ion capacitors are summarized, which focus on their nanostructure designs and chemical preparation methods, such as prepillaring MXenes, delaminated MXenes, and MXene-based hybrids. Finally, some future perspectives and critical challenges of MXene-based material for lithium-ion capacitor application are also presented and briefly discussed.

CAS FGOALS-f3-L Model Datasets for CMIP6 GMMIP Tier-1 and Tier-3 Experiments

Abstract: The Chinese Academy of Sciences (CAS) Flexible Global Ocean–Atmosphere–Land System (FGOALS-f3-L) model datasets prepared for the sixth phase of the Coupled Model Intercomparison Project (CMIP6) Global Monsoons Model Intercomparison Project (GMMIP) Tier-1 and Tier-3 experiments are introduced in this paper, and the model descriptions, experimental design and model outputs are demonstrated. There are three simulations in Tier-1, with different initial states, and five simulations in Tier-3, with different topographies or surface thermal status. Specifically, Tier-3 contains four orographic perturbation experiments that remove the Tibetan–Iranian Plateau, East African and Arabian Peninsula highlands, Sierra Madre, and Andes, and one thermal perturbation experiment that removes the surface sensible heating over the Tibetan–Iranian Plateau and surrounding regions at altitudes above 500 m. These datasets will contribute to CMIP6’s value as a benchmark to evaluate the importance of long-term and short-term trends of the sea surface temperature in monsoon circulations and precipitation, and to a better understanding of the orographic impact on the global monsoon system over highlands.

Disentangling stereotypes from social reality: Astrological stereotypes and discrimination in China.

Abstract: Because stereotypes and social reality are mutually reinforcing, it is often unclear whether a given stereotype has emerged from preexisting social reality, or has shaped social reality over time to resemble the stereotype (e.g., via discrimination). To address this chicken-or-egg problem, we advance an integrative model that captures not only endogenous stereotype formation from social reality, but also exogenous stereotype formation without social reality. When arbitrary social categories are introduced, the cultural meanings of category cues (e.g., semantic category names) can be exogenously projected as stereotypes onto those social categories. To illustrate exogenous stereotype formation, we examined a novel form of stereotyping and discrimination in China based on astrological signs, which were introduced into China from the West. Studies 1a, 1b, and 2 revealed that astrological stereotypes are salient in China (but not in the United States). These stereotypes were likely produced exogenously because of how the signs were translated into Chinese. In particular, Virgos are stereotyped as having disagreeable personalities, likely because of Virgo’s Chinese translation as “virgin” (Study 3). This translation-based stereotype led Chinese individuals to discriminate against Virgos in romantic dating (Study 4) and in simulated job recruitment (Studies 5 and 6). Studies 7 and 8 confirmed that astrological stereotypes are inaccurate and astrological discrimination is irrational: Astrological sign predicted neither personality (N = 173,709) nor job performance (N = 32,878). Overall, our research disentangles stereotypes from social reality by providing a real-world demonstration that stereotypes can form without preexisting social reality, yet still produce discrimination that can then shape social reality. (PsycInfo Database Record (c) 2021 APA, all rights reserved)

Building hierarchical zeolite structure by post-synthesis treatment to promote the conversion of furanic molecules into biofuels

Abstract: The highly selective conversion of furanic molecules to biofuels was achieved on the hierarchical catalysts, which were prepared through modifying the commercially microporous zeolites with sequential alkali and acid post-synthesis treatments. The characterization results indicated that the post-synthesis treatment could successfully introduce the mesopores into the microporous ZSM-5 sample as well as adjust its acidity. The yield of three furanic ethers i.e. 2,5-bis(ethoxymethyl)furan, 5-ethoxymethyl-furfural, and ethyl furfuryl ether on the AT(0.50)-OT catalyst were 94.7%, 90.6%, and 58.2%, respectively. The excellent performance could be attributed to the synergic effect of mass transfer efficiency and surface acidity. This work provides a simple route to prepare high-performance catalysts for the production of biofuels from biochemical.

Decreasing precipitation occurs in daily extreme precipitation intervals across China in observations and model simulations

Abstract: Extreme precipitation response to increasing temperature includes not only changes of frequency and intensity, but also changes of extreme precipitation interval (EPIV) and the precipitation during the neighboring daily extreme precipitations interval (EPIP). These changes have not been fully evaluated yet in observations or climate model simulations although they are very useful to understand variations of extreme precipitation. We used daily precipitation data from 669 meteorological stations during the past five decades across China and projections of 19 general circulation models from CMIP5 under the RCP4.5 and RCP8.5 scenarios to investigate variations of EPIV and EPIP. We found the national average annual EPIV increased across China during the last five decades, while annual EPIP significantly decreased. The decreases mainly occurred in southwest China, east China, and southeast China. At national and regional scales, the average annual EPIV and EPIP showed greater decreases under the RCP8.5 scenario than those under the RCP4.5 scenario from 2006 to 2100. Annual EPIP showed a stronger correlation with extreme precipitation intensity than EPIV. The national average annual EPIP had a significant positive correlation with the Western Pacific Subtropical High Area Index. The abnormal geopotential heights over western Mongolia and the western Pacific at 500 hpa as well as the abnormal SSTs in Japan Sea and the western of Pacific in rainy seasons would result in abnormal annual EPIVs and EPIPs in China. This study may provide references for flooding prediction, water resources management, and disaster prevention and mitigation.

Design, Fabrication, and Test of a 12 T REBCO Insert for a 27 T All-Superconducting Magnet

Abstract: The higher magnetic field is an everlasting goal for researchers in the field of high-field superconducting magnets, for its vital significance to modern science and technology. After achieving our goal of 25 T superconducting magnet project, we set a more ambitious goal to obtain a central field of 27 T, by upgrading the previous 10 T REBCO (REBa2Cu3Ox, RE = rare earth) insert to 12 T. On the basis of the previous 10 T REBCO insert, the newly designed 12 T REBCO insert has an outer REBCO coil, which has the inner and outer diameters of 125 and 150 mm, respectively, and a height of 85 mm. The current grading method and the detailed stress analysis were employed in the design of the added REBCO coil. Stress analysis showed that the maximum hoop stress was reduced from 470 to 438 MPa after employing winding tension, overbanding, and cooldown. The designed highest engineering current density in this added REBCO coil is 383 A/mm2, much higher compared with the previous REBCO insert, the highest of which is only around 300 A/mm2. The rough operation margin for the previous REBCO coil and the added REBCO coil is 42.6% and 43.7%, respectively. This article mainly introduces the design, fabrication, and test results of the 27 T all-superconducting magnet in detail.

Solar thermochemical CO2 splitting with doped perovskite LaCo0.7Zr0.3O3: thermodynamic performance and solar-to-fuel efficiency

Abstract: The research of thermochemical CO2 splitting based on perovskites is a promising approach to green energy development. Performance evaluation was performed towards the doped perovskite LaCo0.7Zr0.3O3 (LCZ-73) based two-step thermochemical CO2 splitting process thermodynamically based on the experimentally derived parameters for the first time. The impacts of vacuum pump and inert gas purge to reduce oxygen partial pressure and CO2 heating on the performance parameter ηsolar-to-fuel have been analyzed. The results showed that at the PO2 of 10−5 bar, non-stoichiometric oxygen δ increased by more than 3 times as the reduction temperature varied from 1000 °C to 1300 °C, however, no significant deviation of δ was observed between 1300 °C and 1400 °C. The reaction enthalpy ranged from 60 to 130 kJ mol−1 corresponding to δ = 0.05–0.40. Comparing the abovementioned two ways to reduce the oxygen partial pressure, the ηsolar-to-fuel of 0.39% and 0.1% can be achieved with 75% and without heat recovery with the CO2 flow rate of 40 sccm under experimental conditions, respectively. The energy cost for CO2 heating during the thermodynamic process as the nCO2/nLCZ-73 increases was obtained from the perspective of energy analysis. The ratio of nCO2/nLCZ-73 at lower temperature required more demanding conditions for the aim of commercialization. Finally, the ability of perovskite to split CO2 and thermochemical performance were tested under different CO2 flow rates. The results showed that high CO2 flow rate was conducive to the production of CO, but at the cost of low ηsolar-to-fuel. The maximum solar-to-fuel efficiency of 1.36% was achieved experimentally at a CO2 flow rate of 10 sccm in the oxidation step and 75% heat recovery.

High humidity alleviates photosynthetic inhibition and oxidative damage of tomato seedlings under heat stress

Abstract: This study investigated the effects of high humidity on the growth and photosynthetic and physiology traits of tomato plants under high temperature stress (HT). The results showed that high humidity effectively alleviated the limitation of HT on plant growth and increased the root-to-shoot ratio. In addition, high humidity also increased the chlorophyll content, net photosynthetic rate, and maximum photochemical quantum yield of PSII in tomato seedlings under HT stress, but declined the stomatal limitation value. Moreover, JIP-test showed that increasing air humidity improved the quantum yields and efficiencies of HT-stressed tomato plants and increased the size of functional antenna, while reduced the activity of a portion of reaction centers. Besides, high humidity increased the activity of antioxidant enzymes, but decreased the content of malondialdehyde and hydrogen peroxide in HT-stressed tomato plants. Therefore, high humidity improved the growth and alleviated photoinhibition and oxidative stress of tomato seedlings under heat stress.

Aqueous ZnCl2 Complex Catalyzed Prins Reaction of Silyl Glyoxylates: Access to Functionalized Tertiary α-Silyl Alcohols.

Abstract: An efficient Prins reaction of silyl glyoxylates in the presence of an aqueous ZnCl2 complex as a catalyst was developed, providing functionalized tertiary α-silyl alcohols in high yields under mil...

Chemical modification of electrospun yttrium silicate fiber with self-healing properties

Abstract: Yttrium silicate is promising materials for the environmental barrier coatings. In this paper, yttrium silicate fiber was successfully prepared by electrostatic spinning, and the microstructure of yttrium silicate fibers was modified by the titanium silicide to improve densification degree of the fiber. In this study, the colloids were obtained by using yttrium nitrate and ethyl orthosilicate as the main raw materials, and the processes such as time and high-temperature calcination were researched. Moreover, the yttrium silicate fibers with different morphologies were obtained by using different proportions of different temperatures and adding different amounts of titanium silicide. The characterization methods such as TG-DSC, SEM, and XRD were used to investigate the preparation process of yttrium silicate fibers. The results show that the temperature has a great effect on the composition of compounds and the morphology of yttrium silicate fibers. The yttrium silicate fiber has the best structure with 15% mixing amount of titanium silicide.

Double Lock of a Potent Human Monoclonal Antibody against SARS-CoV-2

Abstract: Summary Receptor recognition and subsequent membrane fusion are essential for the establishment of successful infection by SARS-CoV-2. Halting these steps can cure COVID-19. Here we have identified and characterized a potent human monoclonal antibody, HB27, that blocks SARS-CoV-2 attachment to its cellular receptor at sub-nM concentrations. Remarkably, HB27 can also prevent SARS-CoV-2 membrane fusion. Consequently, a single dose of HB27 conferred effective protection against SARS-CoV-2 in two established mouse models. Rhesus macaques showed no obvious adverse events when administrated with 10-fold of effective dose of HB27. Cryo-EM studies on complex of SARS-CoV-2 trimeric S with HB27 Fab reveal that three Fab fragments work synergistically to occlude SARS-CoV-2 from binding to ACE2 receptor. Binding of the antibody also restrains any further conformational changes of the RBD, possibly interfering with progression from the prefusion to the postfusion stage. These results suggest that HB27 is a promising candidate for immuno-therapies against COVID-19. Highlights SARS-CoV-2 specific antibody, HB27, blocks viral receptor binding and membrane fusion HB27 confers prophylactic and therapeutic protection against SARS-CoV-2 in mice models Rhesus macaques showed no adverse side effects when administered with HB27 Cryo-EM studies suggest that HB27 sterically occludes SARS-CoV-2 from its receptor

Fog collection on a superhydrophobic/hydrophilic composite spine surface

Abstract: Inspired by numerous plants and animals living in arid conditions, a composite surface with the fog collection capacity has been fabricated in this study. The surface is composed of polydimethylsiloxane-based spine-arrays and a ZnO micron structure. Two wetting properties are integrated on the surface of the spine structure; the tip of spine is processed as hydrophilic and other parts such as the root region of spine and the base are processed as superhydrophobic. When the surface is in the saturated fog flow with a specific tilt angle, the fog deposits on spines and forms condensed droplets; then, the droplets fall off the surface due to gravity. Further, a new cycle of fog collection begins. In this study, we find that the percentage of the hydrophilic tip in the overall spine structure length, the distance between two spines and the tilt angle of surface are the key factors for improving the efficiency of fog collection. Such a composite surface might be an ideal platform for fog collection from air.

Numerical Analysis of Eddy Current Induced by z-Gradient Coil in a Superconducting MRI Magnet

Abstract: In magnetic resonance imaging (MRI), pulsed magnetic gradient fields induce eddy currents in surrounding conducting components of the MRI scanner. These eddy currents distort MRI image and introduce thermal load in cryostat. Ohmic heating of superconducting magnet due to eddy currents changes the operating temperature of magnet, which can lead to system quench. Numerical simulation of these eddy current is important to compensate/control their adverse effects. In this paper, a coupled circuit network method is outlined to model eddy currents in a superconducting magnet that induced by z-gradient coil. According to the axial symmetry, the cylindrical cryostat vessels are divided into several concentric slices with a finite thickness. Each slice is modeled as a series circuit composed of a resistor and an inductor, and inductively coupled with other slices and gradient coil. To improve the calculation efficiency, the Eigen matrix technique is used to simplify the coupled differential matrix equation. The undesired eddy current effects including time-varying secondary magnetic field and power losses are analyzed. In addition, the eddy current behavior due to mechanical errors of gradient coil is discussed. Compared with the simulation results of ideal gradient coil design, the misalignment between primary and secondary layer of z-gradient coil can cause asymmetric secondary magnetic field along z-axis and further introduce $B_{0}$ -shift in imaging area.

Correction: Generation of qualified clinical-grade functional hepatocytes from human embryonic stem cells in chemically defined conditions.

Abstract: The original version of this article contained an error in the name of one of the co-authors (Glyn Nigel Stacey). This has been corrected in the PDF and HTML versions of the article.

Effect of External Field Treatment on the Microstructure and Deformation Behavior of Nickel-Base Superalloy

Abstract: The electrostatic field and electropulsing were applied to the nickel-base superalloy and the effect and mechanism of the external field on the microstructure were investigated in the present study. The results showed that the electrostatic field has significant effect on the vacancy movement and atomic diffusion. As a consequence, a lot of twins can be obtained in the alloy by electrostatic field treatment and both the precipitation and growth of the strengthening phase changed. The plastic deformation resistance of the nickel-based superalloy can be effectively reduced by the adding of pulse current as well as the improvement of the plastic deformation ability. At the same time, the activation energy of the recrystallization can also be reduced by the adding of the pulse current, and the promotion of the nucleation and growth of the recrystallization of the alloy.

Annexina2 as atarget protein for chlorogenic acidin human lung cancerA549cells

Abstract: Chlorogenic acid, an important active component of coffee with anti-tumor activities, has been found for many years. However, the lack of understanding about its target proteins greatly limits the exploration of its anti-tumor molecular mechanism and clinical application. Here, in vitro and animal experiments showed that chlorogenic acid had a significant inhibitory effect on the proliferation of A549 cells. Using the spontaneous fluorescence characteristic of chlorogenic acid to screen the target proteins cleverly to avoid the problem of chemical modification increasing false positive, we identify and verify annexin A2 (ANXA2) as a covalent binding target of chlorogenic acid in A549 cells. Then, we discover that chlorogenic acid as an inhibitor of the binding of ANXA2 to p50 subunit inhibited the expression of downstream anti-apoptotic genes cIAP1 and cIAP2 of NF-{kappa}B signaling pathway in A549 cells in vitro and vivo. Moreover, we find chlorogenic acid hindered the binding of ANXA2 and actin maybe involved in the impediment of tumor cell cycle and migration. Thus, this work demonstrates that chlorogenic acid, as a binding ligand of ANXA2, decrease the expression of NF-{kappa}B downstream anti-apoptotic genes, inhibiting the proliferation of A549 cells in vivo and vitro.

Investigation and improvement of the spin self-sustaining magnetometer

Abstract: The spin self-sustaining atomic magnetometer has the advantage of 1/τ measurement and great development potential in many applications. In this paper, we investigated the main elements that affect the stability and accuracy of the self-sustaining magnetometer and proposed the methods to improve its performance based on the measurement results. The correlation coefficient between fluctuations of the magnetic field generated by coils and the spin Larmor precession frequency is 0.97, which mainly dominates the stability in a short term. The accuracy of the magnetometer is affected by the power and frequency of the pump light. The Larmor precession frequency coefficient related to the pump light power is 26 mHz/mW, and the effect on the Larmor precession frequency is minimized when the pump light frequency is red detuned by 200 MHz from the 85Rb transition D1 line F = 3 to F′ = 3. The 1/τ measurement time after these corrections can be extended to 10 s, and the sensitivity achieved is 149 fT/Hz, which is close to the quantum projection noise limit of the system.