Coronavirus disease 2019 (COVID-19) is a kind of viral pneumonia which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The emergence of SARS-CoV-2 has been marked as the ...third introduction of a highly pathogenic coronavirus into the human population after the severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV) in the twenty-first century. In this minireview, we provide a brief introduction of the general features of SARS-CoV-2 and discuss current knowledge of molecular immune pathogenesis, diagnosis and treatment of COVID-19 on the base of the present understanding of SARS-CoV and MERS-CoV infections, which may be helpful in offering novel insights and potential therapeutic targets for combating the SARS-CoV-2 infection.
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•.The highly pathogenic SARS-CoV-2 appearing in December 2019 can cause COVID-19 and even death in infected persons.•.Coronavirus infections led to the damage of lung, while imbalanced and excessive immune responses may cause pneumonia.•.RT-PCR and CT scans are significant for the diagnosis of SARS-CoV-2 infection, and drugs and vaccines against SARS-CoV-2 are being developed.
•Analyzed and predicted spatiotemporal changes of land use/cover change (LUCC) and ecosystem service value (ESV).•The land-sea gradient changes of LUCC and ecosystem service values (ESVs) were ...analyzed.•Spatially and quantitatively explored the impacts of LUCC on ESVs.
Land use/cover change (LUCC) in the Bohai Rim coastal zone has accelerated as a result of rampant economic development, which has directly caused many negative effects on ecosystem functions and services. Based on multi-temporal land use data (2000, 2005, 2010 and 2015), the benefit transfer method was used to assess the ecosystem service value (ESV) of the Bohai Rim coastal zone, and the impact of LUCC on ecosystem services was studied. Multi-scenario simulations for 2025 were conducted using the future land use simulation model. The result of the analysis showed that during the period from 2000 to 2015, the total ESV lost was 22.09 billion yuan, representing a decrease of 3.80%. The spatial distribution of the ESV showed a certain regularity, with obvious characteristics of a land-sea gradient change. As the distance from the coastline increased, the ESV per unit area gradually declined. Compared with those in 2015, the total ESVs of the socio-economic development scenario and the business-as-usual scenario in 2025 showed a declining trend, while they increased under the ecological protection priority scenario. Under the ecological protection priority scenario, regulating services and support services increased significantly, but those declined dramatically under the socio-economic development scenario. The patterns of LUCC are the main reasons for the decrease in ESV. This research provides a theoretical basis and support for the development and utilization of coastal space and the improvement of “ecological-economic-social” benefits; additionally, the results provide support for scientific decision-making services for the sustainable use of resources in the coastal zone and for the sustainable management of ecosystems.
Cubic boron nitride (c-BN) has the same structure as diamond, and it shows very inert reaction activity in different chemical environments, even under high-pressure (P) and high-temperature (T) ...conditions. Furthermore, the P- and T-dependent Raman shift of c-BN (e.g., TO mode) can be distinguished from that of the diamond anvil (c-BN at ∼1054 cm-1 vs. diamond at ∼1331 cm-1 at ambient conditions), making c-BN a potential P-T sensor for diamond-anvil cell (DAC) experiments. However, the Raman shift of c-BN has not been well studied at high P-T conditions, especially at temperatures above 700 K. In this study, we systematically calibrated the Raman shift of the TO mode (νTO) for synthetic c-BN grains at high-P and high-T conditions up to 15 GPa and 1300 K. Both ruby (Mao et al. 1986) and Sm2+:SrB4O7 (Datchi et al. 2007) were used as internally consistent standards for calibration of c-BN P-T sensor. Our results show that the Raman shift of c-BN is negatively correlated with temperature partial differential VTO/ partial differentialT = -0.02206(71) but positively correlated with pressure partial differential VTO/ partial differentialP = 3.35(2). More importantly, we found that the P-T cross derivative for the Raman shift of c-BN partial differential2VTO/partial differentialP partial differentialT = 0.00105(7) cannot be ignored, as it was assumed in previous studies. The c-BN Raman shift P-T sensor in this study fills the P-T gap ranging from previously performed externally resistance-heated to laser-heated DAC experiments. The effect of c-BN grain size and Raman system laser power on the calibration were also tested for the P-T sensor. In addition, we conducted three sets of high-P-T experiments to test the practicability of c-BN P-T sensor for water-rock interaction experiments in DAC. Testing experiments showed c-BN has very stable chemical activity in water and clear Raman signal at high-P-T conditions in comparison with other P-T sensors (e.g., ruby, Sm2+:SrB4O7, and quartz). Hence, the Raman shifts of c-BN may serve as an ideal P-T sensor for studying water-rock interactions in a DAC, especially at high-P and high-T conditions relevant to subduction zones. MODIF abstract
A poor or mediocre stereoselectivity is a key roadblock for a chiral catalyst to find practical adoptions. We report a facile method to create a tunable chiral space near a chiral catalyst to augment ...its selectivity. The space was created rationally through templated polymerization within cross-linked micelles, using readily available amino acid derivatives. It provided gated entrance of reactants to the catalyst, enabling a mediocre prolinamide to catalyze aldol condensation in water with excellent yields and ee, in a size- and shape-selective manner.
The advent of SELEX (systematic evolution of ligands by exponential enrichment) technology has shown the ability to evolve artificial ligands with affinity and specificity able to meet growing ...clinical demand for probes that can, for example, distinguish between the target leukemia cells and other cancer cells within the matrix of heterogeneity, which characterizes cancer cells. Though antibodies are the conventional and ideal choice as a molecular recognition tool for many applications, aptamers complement the use of antibodies due to many unique advantages, such as small size, low cost, and facile chemical modification. This Minireview will focus on the novel applications of aptamers and SELEX, as well as opportunities to develop molecular tools able to meet future clinical needs in biomedicine.
Advantages of aptamers and SELEX in diverse research fields are summarized in this Minireview, along with some limitations and possible solutions to them. Furthermore described are future perspectives for aptamer modification with a near‐infinite number of molecular‐modulating elements that will result in more powerful tools in bioscience.
Unmanned aerial vehicles (UAVs) may be used for providing seamless network coverage in urban areas for improving the performance of conventional cellular networks. Given the predominantly ...line-of-sight channel of drones, UAV-aided seamless coverage becomes particularly beneficial in case of emergency situations. However, a single UAV having a limited cruising capability is unable to provide seamless long-term coverage, multiple drones relying on sophisticated recharging and reshuffling schemes are necessary. In this context, both the positioning and the flight strategy directly affect the efficiency of the system. Hence, we first introduce a novel UAV energy consumption model, based on which an energy-efficiency-based objective function is derived. Second, we propose an energy-efficient rechargeable UAV deployment strategy optimized under a seamless coverage constraint. Explicitly, a two-stage joint optimization algorithm is conceived for solving both the optimal UAV deployment and the cyclic UAV recharging and reshuffling strategy. Our simulation results quantify the efficiency of our proposed algorithm.
Metasurfaces possess the outstanding ability to tailor phase, amplitude, and even spectral responses of light with an unprecedented ultrahigh resolution and thus have attracted significant interest. ...Here, we propose and experimentally demonstrate a novel meta-device that integrates color printing and computer-generated holograms within a single-layer dielectric metasurface by modulating spectral and spatial responses at subwavelength scale, simultaneously. In our design, such metasurface appears as a microscopic color image under white light illumination, while encrypting two different holographic images that can be projected at the far-field when illuminated with red and green laser beams. We choose amorphous silicon dimers and nanofins as building components and use a modified parallel Gerchberg-Saxton algorithm to obtain multiple subholograms with arbitrary spatial shapes for image-indexed arrangements while avoiding the loss of phase information. Such a method can further extend the design freedom of metasurfaces. By exploiting spectral and spatial control at the level of individual pixels, multiple sets of independent information can be introduced into a single-layer device; the additional complexity and enlarged information capacity are promising for novel applications such as information security and anticounterfeiting.
Microplastics (MPs) as new pollutants of environmental concern have been widely detected in sewage sludge, and may act as significant vectors for metal pollutants due to their adsorption property. ...Our findings show that Cd, Pb, and Co, but not Ni, contents in sewage sludge are lower than that of corresponding metal irons adsorbed on sludge-based MPs, indicating that the MPs accumulate such metal pollutants as Cd in the sludge samples. In contrast to virgin MPs, sludge-based MPs are one order of magnitude higher adsorption capacity for Cd, which reaches up to 2.523 mg g−1, implying that there is a considerable enhancement in adsorption potential of the MPs for metals after the wastewater treatment process. SEM analysis shows that sludge-based MPs have rougher and more porous surface than virgin MPs, and FTIR spectra reveal that functional groups such as CO and OH are found on sludge-based MPs. Further, two-dimensional FTIR correlation spectroscopy indicates that CO and NH functional groups play a vital role in the process that sludge-based MPs adsorb Cd, which are not found in virgin MPs. The results imply that increased adsorption potentials of the sludge-based MPs to Cd are attributed to changes in the MP physicochemical properties during wastewater treatment process. In addition, such factors as pH value, and sludge inorganic and organic components also have an effect on the MP adsorption to Cd. Principal component analysis shows that the MPs could be divided into three categories, i.e. polyamide, rubbery MPs (polyethylene and polypropylene) and glassy MPs (polyvinyl chloride and polystyrene). Their adsorption potentials to Cd follow the decreasing order: polyamide > rubbery MPs > glassy MPs. In summary, these findings indicate that MPs may exert an important influence on fate and transport of metal pollutants during sewage sludge treatment process, which deserves to be further concerned.
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•Some metal pollutants such as Cd and Ni are accumulated on sludge-based MPs.•The contents of metal iron adsorbed on sludge-based and virgin MPs were compared.•An increase in adsorption potential of sludge-based MPs after wastewater treatment.•The enhancement of MPs is resulted from changes in their physicochemical properties.•Types of plastics, pH and sludge components affect the adsorption of MPs to Cd.
Bismuth-based solar cells have exhibited some advantages over lead perovskite solar cells for nontoxicity and superior stability, which are currently two main concerns in the photovoltaic community. ...As for the perovskite-related compound (CH3NH3)3Bi2I9 applied for solar cells, the conversion efficiency is severely restricted by the unsatisfactory photoactive film quality. Herein we report a novel two-step approach high-vacuum BiI3 deposition and low-vacuum homogeneous transformation of BiI3 to (CH3NH3)3Bi2I9for highly compact, pinhole-free, large-grained films, which are characterized with absorption coefficient, trap density of states, and charge diffusion length comparable to those of some lead perovskite analogues. Accordingly, the solar cells have realized a record power conversion of efficiency of 1.64% and also a high external quantum efficiency approaching 60%. Our work demonstrates the potential of (CH3NH3)3Bi2I9 for highly efficient and long-term stable solar cells.
Metasurface holography has the advantage of realizing complex wavefront modulation by thin layers together with the progressive technique of computer-generated holographic imaging. Despite the ...well-known light parameters, such as amplitude, phase, polarization, and frequency, the orbital angular momentum (OAM) of a beam can be regarded as another degree of freedom. Here, we propose and demonstrate orbital angular momentum multiplexing at different polarization channels using a birefringent metasurface for holographic encryption. The OAM selective holographic information can only be reconstructed with the exact topological charge and a specific polarization state. By using an incident beam with different topological charges as erasers, we mimic a super-resolution case for the reconstructed image, in analogy to the well-known STED technique in microscopy. The combination of multiple polarization channels together with the orbital angular momentum selectivity provides a higher security level for holographic encryption. Such a technique can be applied for beam shaping, optical camouflage, data storage, and dynamic displays.
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