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The coronavirus papain-like protease (PLpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for viral polypeptide cleavage and the deISGylation of interferon-stimulated gene 15 (ISG15), which enable it to participate in virus replication and host innate immune pathways. Therefore, PLpro is considered an attractive antiviral drug target. Here, we show that parthenolide, a germacrane sesquiterpene lactone, has SARS-CoV-2 PLpro inhibitory activity. Parthenolide covalently binds to Cys-191 or Cys-194 of the PLpro protein, but not the Cys-111 at the PLpro catalytic site. Mutation of Cys-191 or Cys-194 reduces the activity of PLpro. Molecular docking studies show that parthenolide may also form hydrogen bonds with Lys-192, Thr-193, and Gln-231. Furthermore, parthenolide inhibits the deISGylation but not the deubiquitinating activity of PLpro in vitro. These results reveal that parthenolide inhibits PLpro activity by allosteric regulation.

With the advancement of new power system construction, distribution networks are gradually transforming from being a simple energy receiver and distributor to being an integrated power network that integrates sources, networks, loads, and energy storage with interactive and flexible coupling with the upper-level power grid. However, traditional distribution networks lack active control and distribution capabilities, failing to meet the demands of network transformation and upgrading. To address this issue, this paper proposes a method for solving AC/DC power flow calculation considering an electric energy router (EER) based on an alternating iterative method. Initially, the model for the multi-port EER and three types of power flow models for the AC distribution network, DC distribution network, and EER are constructed. By leveraging the properties of the EER and the hybrid power flow calculation model, a method is proposed for calculating the power flow in the AC/DC hybrid distribution network considering the EER. Finally, by solving the power flow in a medium- and low-voltage AC/DC distribution system, the adaptability of the proposed method is compared. The results demonstrate that the AC/DC hybrid distribution network power flow calculation method established in this paper, which incorporates the EER, possesses high accuracy and adaptability, with an error margin of less than 0.05%. [ABSTRACT FROM AUTHOR]

The diurnal variation and distribution of lunar surficial hydration (OH/H2O) is of great significance for understanding the solar wind implantation and water cycle on the Moon. Lunar south pole is an ideal place to study the diurnal variation of surficial hydration due to the large number of repeat observations of the same region, which is very limited in mid‐ or low‐latitudes. Here we showed clear 0.5‐hr interval diurnal variation of surficial hydration at lunar south pole. The variation of hydration band depth with local time is exactly the opposite to the variation of temperature, indicating that lunar surficial hydration changes sufficiently with temperature. This relationship indicates that both the diurnal variation and hydration content are latitude dependent. Our observations support the hypothesis that the diurnal variation of hydration on the Moon is due to the formation of metastable hydroxyl. Plain Language Summary: Hydration (OH/H2O) has been found on the surface of the Moon due to the implantation of solar wind. Hydration contents in the morning and evening were observed to be higher than that at local noon. Lunar south pole is a very good place to study the diurnal variation of surficial hydration compared with other places of the Moon as there are a lot of repeat observations of the same area at different local times. We conducted a detailed investigation of surficial hydration at the lunar south pole based on repeat Moon Mineralogy Mapper near‐infrared data. We found surficial hydration at lunar south pole gradually decreases toward local noon, and then recovers to the morning level at evening. The variation trend is exactly the opposite to the temperature, indicating lunar surficial hydration changes sufficiently with instantaneous temperature. These observations provide clues for studies on the formation and evolution of volatiles on the Moon and other airless bodies. Key Points: 0.5‐hr interval diurnal variation of lunar surficial hydration was revealed at lunar south pole for the first timeLunar surficial hydration changes sufficiently with instantaneous temperatureLunar surficial hydration did not change when the Moon enters the Earth's magnetotail [ABSTRACT FROM AUTHOR]

Maintaining energy balance and economical operation is significant for energy hub (EH) which serves as the central component. Implementing real‐time regulation for heating and cooling equipment within the EH is challenging due to their slow response time in response to the stochastic fluctuation in renewable energy sources and demands while the opposite is true for electric energy storage equipment (EST), a conventional single timescale energy management strategy is no longer sufficient to take into account the operating characteristics of all equipment. With this motivation, this study proposes a deep reinforcement learning based two‐timescale energy management strategy for EH, which controls heating & cooling equipment on a long timescale of 1 h, and EST on a short timescale of 15 min. The actions of the EST are modelled as discrete to reduce the action spaces, and the discrete‐continuous hybrid action sequential TD3 model is proposed to address the problem of handling both discrete and continuous actions in long timescale policy. A joint training approach based on the centralized training framework is proposed to learn multiple levels of policies in parallel. The case studies demonstrate that the proposed strategy reduces the economic cost and carbon emissions by 1%, and 0.5% compared to the single time‐scale strategy respectively. [ABSTRACT FROM AUTHOR]

The impact threat of some near‐Earth Asteroids (NEAs) drives our need to understand their mineral compositions. Quantitative mineral abundances based on reflectance spectroscopy are of great significance for studying the compositions of NEAs. In this study, we constrained the surface mineralogy of (99942) Apophis based on multiple diagnostic spectral parameters. The influence of non‐mineral component factors (e.g., space weathering, phase angle, and surface temperature) on diagnostic spectral parameters was evaluated. We established the connection between Apophis and corresponding meteorite analog. Our results show that the abundances of olivine and pyroxene on the surface of Apophis are 53.4 ± 6 wt% and 35.6 ± 2 wt%, respectively. The 1 μm band width is basically unaffected by phase‐angle changes and is less affected by temperature variations. Low temperature has more obvious effects on the 1.25/1 μm band depth ratio (BDR 1.25) based on the present data. When the phase angle ranges from 60° to 120°, the BDR 1.25 changes significantly with the increase or decrease of phase angle. In terms of spectral characteristics, the best meteorite analog of Apophis is LL chondrite, confirming earlier interpretations. Mineral analyses based on multiple diagnostic spectral parameters provide more consistent results. Knowledge of the surface compositions of Apophis can also inform optimum or possible defense strategies for it and other NEAs. [ABSTRACT FROM AUTHOR]

With the increasing penetration of new energy sources, the volatility and uncertainty of new energy output can lead to interruptions or fluctuations in the supply of electricity. Power cuts to critical loads can have a significant impact on public safety, social stability, and the economy. Dealing with the effects of uncertainty from new energy sources means we need to find and strengthen the important loads and power sources when designing and operating the power system. Therefore, the assessment of the importance of loads, conventional power sources, and new energy sources is crucial. This paper proposes a power source importance evaluation method based on load importance and new energy uncertainty. The method constructs a load importance evaluation system considering structural characteristics, outage loss, regulation capability, and other factors. To determine the importance of each load, the method uses the ideal solution method and ranks them accordingly. Next, the method calculates the power supply coefficient, which represents the power supply capability of the power source to the critical loads. This calculation involves using the three-point estimation method, which combines the characteristics of the new energy output and the importance of each load. Following that, the evaluation of load importance and the power supply capacity to critical loads is accomplished based on the ideal solution method, taking into account the diversity of power supply characteristics. This comprehensive evaluation allows us to assess the significance of each load and the power supply capability to meet the needs of critical loads, considering the unique characteristics of each power source. Finally, an example analysis is carried out on the IEEE39 to calculate the importance of various types of power sources, which can accurately reflect the power supply capacity of power sources to important loads and verify the validity of the evaluation method. This method provides subsidies for future power system grid planning and operation. [ABSTRACT FROM AUTHOR]

Visible and near‐infrared spectroscopy is a widely used method to determine the mineral compositions of meteorites and asteroids. In this study, we first investigated the association of multiple spectral parameters with mineral compositions using published laboratory spectra and mineral analysis of ordinary chondrites and primitive achondrites. New models for deriving the abundances of mafic silicate minerals were determined. Second, the influence of different mineral compositions on the 1.25 μm region is discussed. Finally, a method to distinguish the ordinary chondrites from primitive achondrites is developed. Our results suggest that the 1.25–1 μm band depth ratio (BDR 1.25) and 1 μm band width (BW I) are mainly associated with mineral abundances and to a lesser extent, compositions. Olivine is the dominant mafic mineral phase that affects the 1.25 μm region in ordinary chondrites and primitive achondrites. The plot of the BDR 1.25 versus the BW I is a useful method for correctly distinguishing about 90% of the primitive achondrites from ordinary chondrites. It relies largely on differences in olivine abundance and olivine/pyroxene ratios and to a lesser extent, olivine composition. The quantitative mineral analysis in this study based on the correlation between the spectra and mineralogy of ordinary chondrites and primitive achondrites provides a chance for understanding the petrology and geochemistry of S‐type asteroids. This study can also distinguish the partially melted S‐type asteroids (parent body of primitive achondrites) from the unmelted S‐type asteroids (parent body of ordinary chondrites). Plain Language Summary: Ordinary chondrites and primitive achondrites are two different types of meteorites with similar mineralogy but different histories: ordinary chondrites have never been significantly heated, while primitive achondrites experienced temperatures high enough to partially melt them. Thus, they represent asteroids with very different thermal histories. Identifying them in the asteroid belt can give us insights into the early thermal history of the Solar System. We examined reflectance spectra of multiple meteorites from both groups and found that we can distinguish them on the basis of the presence or absence of an absorption feature in the 1.2 μm region. This also allows us to determine the abundances of the major mafic minerals (olivine and pyroxene). The method we derived for spectral analysis can be used to determine whether taxonomic S‐type asteroids are primitive (unheated) or have undergone some melting. Key Points: New spectral models to derive the abundances of mafic silicate minerals of ordinary chondrites and primitive achondrites were builtIf olivine is the dominant mineral phase, the 1.25 μm region in ordinary chondrites and primitive achondrites is controlled by its presenceA method to distinguish the ordinary chondrites from primitive achondrites was developed [ABSTRACT FROM AUTHOR]

Controlling the surface traps in metal halide perovskites (MHPs) is essential for device performance, stability, and commercialization. Here, a facile approach is introduced to passivate the methylammonium lead iodide (MAPbI3) perovskite single crystal (PSC) surface defects by benzylamine (BA) ligand treatment, and the natural crystallographic (100) facets surface of PSC is chosen as the research platform to provide a deeper understanding of the passivation process. The confocal photoluminescence (PL) results show that the pristine three-dimensional (3D) MAPbI3 PSC surface with a symmetric emission spectrum is normally converted to a pure two-dimensional (2D) BA2PbI4, and also forms a quasi-2D Ruddlesden–Popper perovskite (RPP) BA2MAn−1PbnI3n+1 (n = 2, 3, 4, ... ∞) after BA exchange with cation defects. The blue shift in the PL peak, as well as the extended exciton lifetimes of time-resolved photoluminescence (TRPL), indicate the realization of surface defect passivation. Additionally, changes in surface morphology are also investigated. The reaction starts with the formation of small, layered crystallites over the surface; as time elapses, the layered crystallites spread and merge in contact with each other, eventually resulting in smooth features. Our findings present a simple approach for MAPbI3 PSC surface defect passivation, which aims to advance MHP optimization processes toward practical perovskite device applications. [ABSTRACT FROM AUTHOR]

Conventional methods for investigating heavy metal contamination in soil are time consuming and expensive. In this study, we (i) explored reflectance spectroscopy as an alternative method for assessing heavy metals, and (ii) further explored the physicochemical mechanism that allows estimation of heavy metals with the reflectance spectroscopy method. We first investigated the spectral response of changing concentrations of heavy metals in soils. The results indicated that only at very high concentration can transition elements exhibit their inherent absorption features. In spite of this observation, we successfully predicted low levels of heavy metals in agricultural soils. The best prediction accuracies were obtained for the siderophile elements Ni, Cr, and Co. The poorest prediction was for Cd. The order of prediction accuracy for metals was approximately the same as the order of their correlation coefficients with Fe. Complementary to some previous studies that found that the intercorrelation between heavy metals and active soil components (such as Fe oxides, organic matter, and clay) is the major predictive mechanism, in the present study we concluded that the correlation with total Fe (including active and residual Fe) is the major mechanism. This conclusion was further supported by both correlation analysis and chemical sequential extraction. Correlation analysis showed that all metals are negatively correlated with reflectance while positively correlated with the absorption depth at about 500 nm, a feature resulting from goethite. The chemical forms of heavy metals, which showed that besides the crystalline Fe oxide and organic matter fractions, heavy metals have significant amounts in the residual fraction, also strengthened the conclusion. Abbreviations: CSE, chemical sequential extraction; ICP-AES, inductively coupled plasma-atomic emission spectroscopy; ICP-MS, inductively coupled plasma-mass spectroscopy; PI, pollution index; PLSR, partial least-squares regression; RMSEP, root-mean-square error of prediction; RPD, ratio of the standard deviation of the population to the root-mean-square error of prediction; VNIRS, visible and near-infrared reflectance spectroscopy.

Carbonaceous chondrites (CCs) are important materials for understanding the early evolution of the solar system and delivery of organic material to the early Earth. Spectral analysis of CCs can establish the relationship between them and their possible parent asteroids, which helps to determine the surface composition of the asteroid. In this paper, the 0.3–26 μm reflectance spectra of a series of coals ranging from lignite to anthracite (Earth analogs of organic matter contained in CCs), a coal heated to various durations and temperatures, and reflectance spectra of CM2 meteorites were analyzed in conjunction with compositional information to derive spectral–compositional relationships. All types of coals have strong aromatic absorptions (3.28 and 5–6.5 μm) and aliphatic "triplet" absorptions (3.38, 3.41, and 3.48 μm). In contrast, CM2 meteorites have obvious aliphatic absorptions and lack aromatic absorptions. The reason is the weak absorption coefficients of aromatic materials and the overlap with strong OH/H2O absorption. Absorptions in the coal spectra are strongly related to elemental H/C ratio. When the H/C ratio is >0.55, the absorption intensity of an aliphatic increases linearly with the increase of H/C. For heated coal, increasing heating time above 1 h at 450 °C causes the disappearance of the aliphatic "triplet" absorptions. Similarly, heating Murchison meteorite to 400 °C for 1 week causes all the organic absorptions to disappear. This implies that in remote sensing detections, only asteroids (e.g., with CM and CI carbonaceous chondrites compositions) that experienced low thermal metamorphism (<400 °C) are suitable as potential targets for detecting organic compounds using features in the 3–4 µm region. [ABSTRACT FROM AUTHOR]

We know very well the Moon's appearance in the visible wavelengths. What the Moon in the midinfrared (MIR) looks like is still a mystery. We present detailed appearance of the MIR Moon observed by a high‐resolution geostationary satellite and reveal the essence behind its appearance. The appearance of the MIR Moon is opposite to its normal visible appearance and shows limb darkening. Both the absolute and the relative brightness distribution of the MIR lunar disk changes with the solar incidence angle i. The signatures of the MIR Moon are controlled by both the reflection and the emission of the lunar surface. The center‐to‐limb temperature variation across the lunar disk is clearly shown. The slower decrease of the brightness temperature when moving away from the subsolar point than the Lambertian model represents topographic effects. Plain Language Summary: The Moon's optical characteristics in visible and thermal infrared have long been observed with our eyes or with instruments. However, what the Moon looks like in the mid‐infrared (MIR) is still a mystery. We show several amazing images of the MIR Moon taken by high‐resolution geostationary satellite for different lunar phases. The entire lunar disk was imaged in high‐resolution single exposure, which is advantageous for investigating the brightness distribution across the lunar disk compared to a mosaic of image frames from lunar‐orbiting spacecrafts. The MIR Moon exhibits opposite trends to its normal visible appearance and shows limb darkening. Both the absolute and the relative brightness distribution of the MIR lunar disk evolve with the changing incidence of the solar illumination. The temperature variation across the lunar disk is also clearly shown. Key Points: We show the MIR Moon's appearance and variation with lunar phaseWe show the center‐to‐limb temperature map of the MoonThe MIR Moon shows limb darkening compared to the Moon in the VNIR [ABSTRACT FROM AUTHOR]

Lunar surface temperature variations provide key information about the thermophysical properties of the regolith. To date, temperatures have been measured using telescopes and orbiter instruments, providing information from mid‐infrared to long infrared (IR) wavelengths. Here, we report on temperature measurements in the short‐wavelength IR at centimeter scales observed in situ by the Chang'E‐4 rover. These local observations are an important complement to the existing large‐scale data. We show that even at 2.39 µm, where reflected radiation dominates the spectrum, thermal information can be retrieved from the data. The observed thermal radiances and derived temperatures depend on the observation geometry, specifically the relative azimuth angle between Sun and detector. This indicates that surface roughness on subresolution (millimeter) scales causes a non‐Lambertian radiation pattern of the emitted flux that is per definition independent of the observation angle. This behavior must be considered when deriving temperatures and thermal properties of lunar regolith. Plain Language Summary: The Chang'E‐4 spacecraft landed in the Von Kármán Crater in the Moon's South Pole‐Aitken Basin. A Visible and Near Infrared Spectrometer (VNIS) was carried on the "Yutu‐2" rover. The VNIS measured thermal emission on the surface of the Moon at short wavelengths and temperature variations at centimeter scales were retrieved during the first, second, and tenth day of rover operations on the lunar surface. These in situ observations are an important complement to the existing large‐scale measurements taken from orbit and reveal that the millimeter scale roughness plays an important role when deriving temperatures and physical properties of the lunar surface regolith. Key Points: The Chang'E‐4 VNIS observed the lunar surface in situ in the 0.45–2.4 μm wavelength rangeEmitted flux at centimeter scales is non‐Lambertian and depends on surface roughness and observation geometrySurface roughness as described by the bidirectional RMS slope was found to be 22°–24° [ABSTRACT FROM AUTHOR]

The inferior stability of perovskite solar cells (PSCs) under ultraviolet (UV) irradiation has been a bottleneck for their further commercialization. Herein, we report a simple strategy to enhance the UV stability of PSCs by using an alkaloid 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) doped C60 electron transport layer (ETL). By improving the electron mobility of ETLs to 2 cm2 V−1 s−1 and optimizing the conduction band position to 4.2 eV, the DBU-doped C60 (DBU-C60) ETLs enable the rigid and flexible planner n-i-p PSCs to exhibit PCEs of 20% and 16%, respectively. Most importantly, the devices based on the DBU-C60 ETLs retain over 80% of their initial efficiency after storage either under UV irradiation for 336 h or light socking for 1000 h in an ambient environment. These results indicate that the optimized C60 is a promising electron transport material to stabilize the PSCs under UV light illumination without the cost of efficiency loss. [ABSTRACT FROM AUTHOR]

Optofluidic time-stretch quantitative phase imaging (OTS-QPI) is a potent tool for biomedical applications as it enables high-throughput QPI of numerous cells for large-scale single-cell analysis in a label-free manner. However, there are a few critical limitations that hinder OTS-QPI from being widely applied to diverse applications, such as its costly instrumentation and inherent phase-unwrapping errors. Here, to overcome the limitations, we present a QPI-free OTS-QPI method that generates "virtual" phase images from their corresponding bright-field images by using a deep neural network trained with numerous pairs of bright-field and phase images. Specifically, our trained generative adversarial network model generated virtual phase images with high similarity (structural similarity index >0.7) to their corresponding real phase images. This was also supported by our successful classification of various types of leukemia cells and white blood cells via their virtual phase images. The virtual OTS-QPI method is highly reliable and cost-effective and is therefore expected to enhance the applicability of OTS microscopy in diverse research areas, such as cancer biology, precision medicine, and green energy. [ABSTRACT FROM AUTHOR]

A fused tetraphenylethylene-based hole transporting material shows higher power conversion efficiency and better stability compared with its non-fused counterpart, and the former molecule even outperforms the conventional spiro-OMeTAD. [ABSTRACT FROM AUTHOR]

• Colorful defective TiO 2-x microspheres cooperating with titanium Schiff base complex were synthesized. • The formation mechanism of TiO 2-x -Ti(acacen) y complexes was proposed based on the Schiff base reaction. • Ti3+ and oxygen vacancies are self-doped into TiO 2 lattice to form defective TiO 2-x. • Red TiO 2-x -Ti(acacen) y complexes have a narrow bandgap of 2.16 eV and high specific surface area over 255.4 m2 g−1. • Red TiO 2-x -Ti(acacen) y complexes show high performance of photocatalysis superior to yellowish TiO 2 microspheres. As a promising photocatalyst, the large band gap of TiO 2 imposes restriction on its light absorption in the visible region, making it less application in industrial fields. Herein, we design a facile solvothermal method to fabricate colorful defective TiO 2-x microspheres with controllable morphological and porous structure, large specific surface area and tunable band gap on the basis of the Schiff base reaction between acetylacetone and ethylenediamine which produce bis(acetylacetone)ethylenediamine (acacen). The acacen, as a tetradentate Schiff-base ligand, has four binding sites which can stabilize titanium centers to produce titanium Schiff base complexes. The color of TiO 2-x -Ti(acacen) y complexes changes from yellowish to brown and red with the variation of the acacen ligand, and the corresponding bandgap narrows from 3.25 eV to 2.16 eV as a result of the newly formed Ti3+ and oxygen vacancies (Vo) in the TiO 2 lattice. In addition, red TiO 2-x microspheres cooperating with titanium Schiff base complex demonstrate high photocatalytic efficiency in methylene blue under visible light as well as hydroxyl radical generation in contrast to yellowish TiO 2 microspheres, revealing the significance of this strategy for morphological and bandgap manipulation in defective TiO 2-x nanomaterials for high-performance photocatalysis. [ABSTRACT FROM AUTHOR]