•Microbial fermentation is the key factor controlling the quality of dark tea.•Serial reactions modify the chemical constituents of tea leaves during fermentation.•Multi-omics approaches are used to ...reveal microbial impact on dark tea quality.
Dark tea is a unique fermented tea produced by solid-state fermentation of tea leaves (Camellia sinensis). It includes ripe Pu-erh tea, Fu brick tea, Liupao tea, and other teas. Microbial fermentation is considered to be the key factor controlling the quality of dark tea. It involves a series of reactions that modify the chemical constituents of tea leaves. These chemical conversions during microbial fermentation of dark tea are associated with a variety of functional core microorganisms. Further, Multi-omics approaches have been used to reveal the microbial impact on the conversion of the chemical components in dark tea. In the present review, we provide an overview of the most recent advances in the knowledge of the microbial bioconversion of the chemical components in dark tea, including the chemical composition of dark tea, microbial community composition and dynamics during the fermentation process, and the role of microorganisms in biotransformation of chemical constituents.
Vascular disease remains the leading cause of death and disability, the etiology of which often involves atherosclerosis. The current treatment of atherosclerosis by pharmacotherapy has limited ...therapeutic efficacy. Here we report a biomimetic drug delivery system derived from macrophage membrane coated ROS-responsive nanoparticles (NPs). The macrophage membrane not only avoids the clearance of NPs from the reticuloendothelial system, but also leads NPs to the inflammatory tissues, where the ROS-responsiveness of NPs enables specific payload release. Moreover, the macrophage membrane sequesters proinflammatory cytokines to suppress local inflammation. The synergistic effects of pharmacotherapy and inflammatory cytokines sequestration from such a biomimetic drug delivery system lead to improved therapeutic efficacy in atherosclerosis. Comparison to macrophage internalized with ROS-responsive NPs, as a live-cell based drug delivery system for treatment of atherosclerosis, suggests that cell membrane coated drug delivery approach is likely more suitable for dealing with an inflammatory disease than the live-cell approach.
Tea is one of the most popular beverages across the world and is made exclusively from cultivars of Camellia sinensis. Many wild relatives of the genus Camellia that are closely related to C. ...sinensis are native to Southwest China. In this study, we first identified the distinct genetic divergence between C. sinensis and its wild relatives and provided a glimpse into the artificial selection of tea plants at a genome-wide level by analyzing 15,444 genomic SNPs that were identified from 18 cultivated and wild tea accessions using a high-throughput genome-wide restriction site-associated DNA sequencing (RAD-Seq) approach. Six distinct clusters were detected by phylogeny inferrence and principal component and genetic structural analyses, and these clusters corresponded to six Camellia species/varieties. Genetic divergence apparently indicated that C. taliensis var. bangwei is a semi-wild or transient landrace occupying a phylogenetic position between those wild and cultivated tea plants. Cultivated accessions exhibited greater heterozygosity than wild accessions, with the exception of C. taliensis var. bangwei. Thirteen genes with non-synonymous SNPs exhibited strong selective signals that were suggestive of putative artificial selective footprints for tea plants during domestication. The genome-wide SNPs provide a fundamental data resource for assessing genetic relationships, characterizing complex traits, comparing heterozygosity and analyzing putatitve artificial selection in tea plants.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The development of high‐performance transparent conductors (TCs) is critical to various technologies from transparent electronics to solar cells. Whereas n‐type TCs have been extensively applied in ...many electronic devices, their p‐type counterparts have not been largely commercialized due to the lack of ideal materials. Combining atomic replacement and first‐principles calculations, seven stable layered double perovskites are identified, i.e., Cs4CuSb2Cl12‐like Cs4M2+B3+2XVII12 compounds as promising p‐type TCs with sufficiently large bandgaps, delocalized wavefunction distribution with s‐orbital components in valence band maximum (VBM) and the antibonding character of VBM to ensure their optical transparency, light hole effective masses, and intrinsic good p‐type conductivities, respectively. Taking Cs4CdSb2Cl12 as a representative example, it is demonstrated that under Cd‐poor (Cl‐rich) conditions, Cs4CdSb2Cl12 could exhibit excellent p‐type conductivity with high hole concentration, contributed by the intrinsic shallow‐acceptor CdSb with extremely low formation energy. Generally, the other 6 Cs4M2+B3+2XVII12 compounds exhibit similar intrinsic p‐type defect properties as Cs4CdSb2Cl12, which could rank them as the top p‐type TCs discovered or predicted until now.
Combining atomic replacement and first‐principles calculations, seven Cs4M2+B3+2XVII12 layered perovskite compounds as promising intrinsic p‐type transparent conductors are identified. They exhibit good crystallographic, dynamical and thermodynamic stabilities, optical transparency, light hole effective masses, and intrinsic good p‐type conductivities.
Two-dimensional transition metal carbides are notable as promising anode materials for Li-ion batteries (LIBs). Using first-principle calculations, we investigate the effect of vacancies on the Li ...adsorption and diffusion on Ti2C and Ti2CT2 (where T denotes surface terminations, F or OH) monolayers. Interestingly, we find that the carbon vacancies (VC) tend to enhance the adsorption of Li in Ti2C monolayer, whereas the titanium vacancies (VTi) play a similar role in Ti2CT2 when functional groups present. The presence of vacancies further leads to a change in the diffusion behavior of Li atoms. In this context, we propose an idea to mitigate the adverse effects on Li diffusion performance by regulating the functional groups. In the presence of VC, the surface of Ti2C monolayer is suggested to be modified with OH– groups due to its relatively low diffusion barrier in the range of 0.025–0.037 eV when Li diffuses around VC, whereas in the presence of VTi, the surface is suggested to remove the functional groups, resulting in a decrease of energy barrier by about 1 eV when Li atom diffuses around VTi. The present study may provide a guideline to improve the Li-ion storage performance of Ti2C monolayers as electrode materials in LIBs, with atomic vacancies being taken into consideration.
Halide double perovskites (HDPs) are promising lead‐free perovskites for various optoelectronic applications. However, the device performances of HDPs are far below the optimized values, which open a ...critical question regarding the origin of low performance in these HDPs. In this article, using first‐principles calculations, it is found that some types of grain boundaries (GBs) are easy to form in polycrystalline HDPs. Importantly, the existence of low‐energy Σ5(310) GBs can induce harmful deep‐level defect states within the bandgaps of type‐I (e.g., Cs2AgInCl6) and type‐II (e.g., Cs2AgBiCl6) HDPs, which may dramatically reduce the device performances. Interestingly, it is found that the formation of some intrinsic defects and defect complexes could effectively eliminate these deep‐levels in type‐II and type‐I HDPs, respectively. Under some exactly predesigned growth conditions identified by utilizing thousands of chemicals through a potential screening process, these defects or defect complexes can spontaneously incorporate into the GB cores, meanwhile the harmful deep‐level defects in the bulk can also be effectively eliminated. In addition, the self‐passivated GBs could generate band bending, which may be beneficial for charge separation. The understanding of GB formation as well as the self‐passivation mechanism in HDPs can provide a new viewpoint and guidance for designing polycrystalline perovskites with improved optoelectronic performance.
Under some exactly predesigned growth conditions identified by utilizing thousands of chemicals through a potential screening process, some intrinsic defects or defect complexes can spontaneously incorporate into the grain boundary (GB) cores, and effectively eliminate the harmful deep‐levels induced by the low‐energy GBs in lead‐free halide double perovskites (type‐I and type‐II).
Lead-free halide double perovskites (HDPs) are expected to be promising photovoltaic (PV) materials beyond organic–inorganic halide perovskite, which is hindered by its structural instability and ...toxicity. The defect- and stability-related properties of HDPs are critical for the use of HDPs as important PV absorbers, yet their reliability is still unclear. Taking Cs2AgInBr6 as a representative, we have systemically investigated the defect properties of HDPs by theoretical calculations. First, we have determined the stable chemical potential regions to grow stoichiometric Cs2AgInBr6 without structural decomposition. Second, we reveal that Ag-rich and Br-poor are the ideal chemical potential conditions to grow n-type Cs2AgInBr6 with shallow defect levels. Third, we find the conductivity of Cs2AgInBr6 can change from good n-type, to poorer n-type, to intrinsic semiconducting depending on the growth conditions. Our studies provided important guidance for experiments to fabricate Pb-free perovskite-based solar cell devices with superior PV performances.
What a turnover! An efficient chiral iridium catalyst that bears a tridentate spiro aminophosphine ligand catalyzes the asymmetric hydrogenation of ketones with excellent enantioselectivities (up to ...99.9 % ee) and extremely high turnover numbers (TONs; as high as 4 550 000).
An unprecedented reaction for the direct trifluoromethylthiolation and fluorination of alkyl alcohols using AgSCF3 and nBu4NI has been developed. The trifluoromethylthiolated compounds and alkyl ...fluorides were selectively formed by changing the ratio of AgSCF3/nBu4NI. This protocol is tolerant of different functional groups and might be applicable to late‐stage trifluoromethylthiolation of alcohols.
Silver bullet: A new strategy has been developed for the direct trifluoromethylthiolation of alkyl alcohols using AgSCF3 and nBu4NI. This protocol does not require the activation of alcohols in advance. A variety of alkyl alcohols bearing different functional groups were transformed into the corresponding alkyl trifluoromethyl sulfides in moderate to good yields.
•We report a familial cluster of COVID-19 to assess potential transmission of the disease during the incubation period.•A familial cluster of four patients with COVID-19 in Zhoushan, China had ...contact with an asymptomatic family member, who developed symptoms later.•The infectivity during the incubation period for SARS-CoV-2 is a big challenge for controlling the disease.
We report a familial cluster of 2019 novel coronavirus disease (COVID-19) to assess its potential transmission during the incubation period. The first patient in this familial cluster was identified during the presymptomatic period, as a close contact of a confirmed patient. Five family members had close contact with this first patient during his incubation period, with four of them confirmed positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the subsequent sampling tests.
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