Ionic transport in organometal halide perovskites is of vital importance because it dominates anomalous phenomena in perovskite solar cells, from hysteresis to switchable photovoltaic effects. ...However, excited state ionic transport under illumination has remained elusive, although it is essential for understanding the unusual light-induced effects (light-induced self-poling, photo-induced halide segregation and slow photoconductivity response) in organometal halide perovskites for optoelectronic applications. Here, we quantitatively demonstrate light-enhanced ionic transport in CH
NH
PbI
over a wide temperature range of 17-295 K, which reveals a reduction in ionic transport activation energy by approximately a factor of five (from 0.82 to 0.15 eV) under illumination. The pure ionic conductance is obtained by separating it from the electronic contribution in cryogenic galvanostatic and voltage-current measurements. On the basis of these findings, we design a novel light-assisted method of catalyzing ionic interdiffusion between CH
NH
I and PbI
stacking layers in sequential deposition perovskite synthesis. X-ray diffraction patterns indicate a significant reduction of PbI
residue in the optimized CH
NH
PbI
thin film produced via light-assisted sequential deposition, and the resulting solar cell efficiency is increased by over 100% (7.5%-15.7%) with little PbI
residue. This new method enables fine control of the reaction depth in perovskite synthesis and, in turn, supports light-enhanced ionic transport.
Nitrate‐containing industrial wastewater poses a serious threat to the global food security and public health safety. As compared to the traditional microbial denitrification, electrocatalytic ...nitrate reduction shows better sustainability with ultrahigh energy efficiency and the production of high‐value ammonia (NH3). However, nitrate‐containing wastewater from most industrial processes, such as mining, metallurgy, and petrochemical engineering, is generally acidic, which contradicts the typical neutral/alkaline working conditions for both denitrifying bacteria and the state‐of‐the‐art inorganic electrocatalysts, leading to the demand for pre‐neutralization and the problematic hydrogen evaluation reaction (HER) competition and catalyst dissolution. Here, we report a series of Fe2M (M=Fe, Co, Ni, Zn) trinuclear cluster metal–organic frameworks (MOFs) that enable the highly efficient electrocatalytic nitrate reduction to ammonium under strong acidic conditions with excellent stability. In pH=1 electrolyte, the Fe2Co‐MOF demonstrates the NH3 yield rate of 20653.5 μg h−1 mg−1site with 90.55 % NH3‐Faradaic efficiency (FE), 98.5 % NH3‐selectivity and up to 75 hr of electrocatalytic stability. Additionally, successful nitrate reduction in high‐acidic conditions directly produce the ammonium sulfate as nitrogen fertilizer, avoiding the subsequent aqueous ammonia extraction and preventing the ammonia spillage loss. This series of cluster‐based MOF structures provide new insights into the design principles of high‐performance nitrate reduction catalysts under environmentally‐relevant wastewater conditions.
Efficient, direct, electrocatalytic ammonia production from nitrate in a strong acid environment is possible by using the efficient electron proton conduction capability of the dinitrogen ligand and the metal active site in an Fe‐based trinuclear cluster metal–organic framework (MOF).
An asymmetric approach to access 2‐substituted isoindolin‐1‐ones 9–11 was developed through TiCl4‐mediated addition‐chlorination of N,O‐acetals 7 a–7 c with terminal alkynes 8. A range of substrates ...were amenable to this transformation, and the desired substituted isoindolin‐1‐ones were obtained in moderate to good yields with moderate diastereoselectivities.
An efficient method to obtain 2‐substituted isoindolin‐1‐ones have been established by TiCl4‐mediated addition‐chlorination of N,O‐acetals with terminal alkynes. A range of substrates were amenable to this transformation, and a series of desired substituted isoindolin‐1‐ones were obtained in moderate to good yields with moderate diastereoselectivities. Moreover, the one pot chlorination is an additional advantage of this method.
Although vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are under development, the antigen epitopes on the virus and their immunogenicity are poorly understood. Here, ...we simulate the 3D structures and predict the B cell epitopes on the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches and validate epitope immunogenicity by immunizing mice. Almost all 33 predicted epitopes effectively induce antibody production, six of these are immunodominant epitopes in individuals, and 23 are conserved within SARS-CoV-2, SARS-CoV, and bat coronavirus RaTG13. We find that the immunodominant epitopes of individuals with domestic (China) SARS-CoV-2 are different from those of individuals with imported (Europe) SARS-CoV-2, which may be caused by mutations on the S (G614D) and N proteins. Importantly, we find several epitopes on the S protein that elicit neutralizing antibodies against D614 and G614 SARS-CoV-2, which can contribute to vaccine design against coronaviruses.
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•B cell epitopes of SARS-CoV-2 are obtained using structure-based approaches•The predicted epitopes effectively induce robust antibody responses•D614 and G614 SARS-CoV-2 display different immunodominant epitopes•Epitopes on S protein elicit D614 and/or G614 SARS-CoV-2-neutralizing antibodies
Lu et al. predict and validate B cell epitopes on the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches. The immunodominant epitopes vary between D614 and G614 SARS-CoV-2. The epitopes on the S protein elicit neutralizing antibodies against D614 and G614 SARS-CoV-2.
Antimony selenide (Sb2Se3) is a highly promising photovoltaic material thanks to its outstanding optoelectronic properties, as well as its cost‐effective and eco‐friendly merits. However, toxic CdS ...is widely used as an electron transport layer (ETL) in efficient Sb2Se3 solar cells, which largely limit their development toward market commercialization. Herein, an effective green Cd‐free ETL of SnOx is introduced and deposited by atomic layer deposition method. Additionally, an important post‐annealing treatment is designed to further optimize the functional layers and the heterojunction interface properties. Such engineering strategy can optimize SnOx ETL with higher nano‐crystallinity, higher carrier density, and less defect groups, modify Sb2Se3/SnOx heterojunction with better interface performance and much desirable “spike‐like” band alignment, and also improve the Sb2Se3 light absorber layer quality with passivated bulk defects and prolonged carrier lifetime, and therefore to enhance carrier separation and transport while suppressing non‐radiative recombination. Finally, the as‐fabricated Cd‐free Mo/Sb2Se3/SnOx/ITO/Ag thin‐film solar cell exhibits a stimulating efficiency of 7.39%, contributing a record value for Cd‐free substrate structured Sb2Se3 solar cells reported to date. This work provides a viable strategy for developing and broadening practical applications of environmental‐friendly Sb2Se3 photovoltaic devices.
Actomic layer deposition processed SnOx is introduced as electron transport layer in Sb2Se3 thin‐film solar cells. An additional post‐annealing can remarkably enhance the photovoltaic performance, thanks to the optimized carrier dynamics under simultaneously improving the properties of SnOx, Sb2Se3/SnOx heterojunction and Sb2Se3 absorber layer. A stimulating efficiency of 7.39% represents the record value for Cd‐free substrate structured Sb2Se3 solar cells.
Precipitation is known to have legacy effects on plant diversity and production of many terrestrial ecosystems. Precipitation regimes are expected to become more variable with increasing extreme ...precipitation events. However, how previous-year precipitation regimes affect the current-year aboveground biomass (AGB) remains largely unknown. Here we measured long-term (2004–2017) AGB in a semi-arid grassland of the Chinese Loess Plateau to evaluate the impact of previous-year precipitation amount on current-year AGB. Furthermore, to assess the response of current-year AGB to previous-year precipitation regimes, we conducted a field manipulation experiment that included three precipitation regimes during 2014–2017: (i) ambient precipitation, (ii) monthly added four 5 mm rain events, and (iii) monthly added one 20 mm event. Both the long-term (2004–2017) observations under ambient precipitation and short-term (2014–2017) measurements under manipulative treatments showed significant positive effects of previous-year precipitation on current-year AGB. Our path analysis suggested that previous-year precipitation frequency had negative effects on the current-year density and mean height of grass (Leymus secalinus) while had positive effects on forb (Artemisia capillaris). The forb had much smaller height and AGB (65% and 53% less, respectively) than the grass. Consequently, the AGB reduced in the weekly small events treatment, causing the sensitivity of AGB to precipitation to decrease. Therefore, our findings indicated that the impacts of precipitation regimes on plant community dynamics should be taken into consideration while assessing the precipitation legacy effect on ecosystem production.
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•Current-year aboveground biomass (AGB) increased linearly with previous-year precipitation.•Precipitation frequency negatively affects the sensitivity of AGB to precipitation.•Previous-year precipitation amount increases the current-year grass density.•Previous-year precipitation frequency increases the current-year forb density.
Four undescribed steroidal compounds along with twenty known compounds were isolated from n‐butanol extracted fraction of the whole plants of Solanum lyratum Thunb (SLNF). Their structures were ...assigned based on analyses of the extensive spectroscopic data (including MS, 1D/2D NMR, and ECD) or comparisons of the NMR data with those reported. Among the knowns, three compounds were isolated from Solanum plants for the first time, while one compound was isolated from S. lyratum for the first time. In addition, the cytotoxicities of these isolates against human colon SW480 and hepatoma Hep3B cells were evaluated by a MTT assay. And, nine of them and SLNF exhibited significant activities against both SW480 and Hep3B cells, while twelve of them significantly inhibited the activities of SW480 cells. This study allows for the exploitation of chemical markers with potential significance in discrimination of Solanum plants, and uncovers the diverse steroidal constituents from S. lyratum dedicated for its future application in cancer treatment.
The expression of galectin-1, one of the most important lectins participating in the malignant tumor development, has been shown to be regulated by hypoxia, but its exact mechanism remains elusive. ...Here, we find that ectopically expressed hypoxia-inducible factor (HIF) 1α protein, an oxygen-sensitive subunit of HIF-1 that is a master factor for cellular response to hypoxia, significantly increases galectin-1 expression in both messenger RNA and protein levels in all four colorectal cancer (CRC) cell lines tested. However, hypoxia-induced galectin-1 expression cannot be seen in sentrin/SUMO-specific protease 1 homozygous-null mouse embryonic fibroblasts that fail to accumulate HIF-1α protein. Furthermore, silence of HIF-1α or HIF-1β expression by specific short hairpin RNAs (shRNAs) antagonizes hypoxia-induced galectin-1 expression. All these results propose that galectin-1 is a direct target of transcriptional factor HIF-1. Applying luciferase reporter assay and chromatin immunoprecipitation, we identify that two hypoxia-responsive elements located at −441 to −423 bp upstream to transcriptional start site of galectin-1 gene are essential for HIF-1-mediated galectin-1 expression. Finally, the knockdown of galectin-1 by its specific shRNA can significantly reduce hypoxia-induced invasion and migration of CRC cell line, and the ectopic expression of galectin-1 can remarkably restore invasion and migration abilities of HIF-1α-knocked SW620 cells, proposing that galectin-1 mediates the HIF-1-induced migration and invasion of CRC cells during hypoxia. Taken together, our results shed new light for understanding mechanism for hypoxia/HIF-1-mediated migration/invasion of CRC cells.
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