Inorganic cesium lead iodide perovskite CsPbI3 is attracting great attention as a light absorber for single or multi‐junction photovoltaics due to its outstanding thermal stability and proper band ...gap. However, the device performance of CsPbI3‐based perovskite solar cells (PSCs) is limited by the unsatisfactory crystal quality and thus severe non‐radiative recombination. Here, vacuum‐assisted thermal annealing (VATA) is demonstrated as an effective approach for controlling the morphology and crystallinity of the CsPbI3 perovskite films formed from the precursors of PbI2, CsI, and dimethylammonium iodide (DMAI). By this method, a large‐area and high‐quality CsPbI3 film is obtained, exhibiting a much reduced trap‐state density with prolonged charge lifetime. Consequently, the solar cell efficiency is raised from 17.26 to 20.06 %, along with enhanced stability. The VATA would be an effective approach for fabricating high‐performance thin‐film CsPbI3 perovskite optoelectronics.
A vacuum‐assisted thermal annealing approach is employed for the fabrication of CsPbI3 perovskite films with full surface coverage and enhanced crystallization. The resultant CsPbI3 perovskite solar cells exhibit a power conversion efficiency (PCE) as high as 20.06 %, along with enhanced long‐term stability.
To control mechanical waves and structural vibrations, an important method is to design metamaterials with tailored elastic constants, but it is very difficult. In this paper, a simple and universal ...metamaterial design method is proposed. This orthotropic metamaterial is composed of elements arrayed periodically in space. The element includes two cuboid structures. The first structure is the basic structure of the element, and the second structure is the transformation of the first structure of the element. The first structure of the element is a cuboid structure composed of 24 bars connected by 8 nodes, and the second structure of the element is a cuboid structure composed of 36 bars connected by 14 nodes. This metamaterial has six independent elastic constants, so there is a large degree of freedom in the material design. Therefore, it has great application value in the fields of mechanical metamaterials, elastic wave metamaterials, acoustic metamaterials, and seismic metamaterials, and has also laid the foundation for realizing the dream of controlling mechanical waves and structural vibrations.
Tin‐based halide perovskite materials have been successfully employed in lead‐free perovskite solar cells, but the overall power conversion efficiencies (PCEs) have been limited by the high carrier ...concentration from the facile oxidation of Sn2+ to Sn4+. Now a chemical route is developed for fabrication of high‐quality methylammonium tin iodide perovskite (MASnI3) films: hydrazinium tin iodide (HASnI3) perovskite film is first solution‐deposited using presursors hydrazinium iodide (HAI) and tin iodide (SnI2), and then transformed into MASnI3 via a cation displacement approach. With the two‐step process, a dense and uniform MASnI3 film is obtained with large grain sizes and high crystallization. Detrimental oxidation is suppressed by the hydrazine released from the film during the transformation. With the MASnI3 as light harvester, mesoporous perovskite solar cells were prepared, and a maximum power conversion efficiency (PCE) of 7.13 % is delivered with good reproducibility.
High‐quality, pinhole‐free CH3NH3SnI3 films are achieved from pristine NH2NH3SnI3 perovskite, and the oxidation of Sn2+ to Sn4+ can be efficiently suppressed owing to the reduction agent hydrazine generated inside the films in the conversion. With the CH3NH3SnI3 film as light absorber, mesoporous MASnI3 perovskite solar cells were fabricated with a maximum PCE of 7.13 %.
With the continuous development of literature and art, vocal education, as an important part of aesthetic education, has also been developed unprecedentedly. This paper constructs a music emotion ...recognition model based on deep learning and the Lstm network. The preprocessing of music is accomplished through the methods of pre-emphasis, frame-splitting, and windowing so as to improve the purity of the music signal. Using the Mel frequency cepstrum coefficient and cochlear frequency, the music analog signal is converted into frequency features so as to better distinguish the acoustic features and combined with Word2vec to realize the extraction of music emotion features. By comparing the Lstm music emotion recognition model with other models, the performance of this paper’s model is verified in terms of classification accuracy. To understand the role of its embodiment, the music recognition model is applied to the teaching of ethnic music. The results show that the average fitness of Lstm music recognition is 75%-90% with the increase of the number of evolutions, and the average fitness of Lstm objective function reaches the peak at the number of iterations of 40, with a fitness of 95%. Under the music recognition model, the students’ spectrum is elevated to 0db above the reference line, and the amplitude mostly floats in the interval in (-3, -15), and the teacher can formulate appropriate ethnic vocal music teaching for the students’ spectrum.
A palladium‐catalyzed enantioselective sequential ring‐opening/cross‐coupling of cyclobutanones is disclosed that provides chiral indanones bearing C3‐quaternary stereocenters. The reaction process ...involves palladium‐catalyzed nucleophilic addition of cyclobutanones and aryl halides, enantioselective β‐carbon elimination, and intermolecular trapping of a transient σ‐alkylpalladium complex with boronic acids. Alternatively, an intramolecular cyclopropanation is realized through C−H bond functionalization in the absence of external coupling reagents, affording chiral cyclopropane‐fused‐indanones in good yields and enantioselectivity.
Enantioselective desymmetrization of prochiral cyclobutanones was realized through tandem palladium‐catalyzed ring‐opening/cyclopropanation to provide chiral cyclopropane‐fused indanones. With external coupling reagents, the transient σ‐alkylpalladium intermediate can be captured to afford an array of chiral indanones bearing C3‐quaternary stereocenters.
Abstract
Defects from grain interiors and boundaries of perovskite films cause significant nonradiative recombination energy loss, and thus perovskite films with controlled crystallinity and large ...grains is critical for improvement of both photovoltaic performance and stability for perovskite-based solar cells. Here, a methylamine (MA
0
) gas-assisted crystallization method is developed for fabrication of methylammonium lead iodide (MAPbI
3
) perovskite films. In the process, the perovskite film is formed via controlled release of MA0 gas molecules from a liquid intermediate phase MAPbI
3
·xMA
0
. The resulting perovskite film comprises millimeter-sized grains with (110)-uniaxial crystallographic orientation, exhibiting much low trap density, long carrier lifetime, and excellent environmental stability. The corresponding perovskite solar cell exhibits a power conversion efficiency (PCE) of ~ 21.36%, which is among the highest reported for MAPbI
3
-based devices. This method provides important progress towards the fabrication of high-quality perovskite thin films for low-cost, highly efficient and stable perovskite solar cells.
Single‐crystalline Ni‐rich cathode (SC‐NCM) has attracted increasing interest owing to its greater capacity retention in advanced solid‐state lithium batteries (SSLBs), while suffers from severe ...interfacial instability during cycling. Here, via atomic layer deposition, Li3PO4 is introduced to coat SC‐NCM (L‐NCM), to suppress undesired side reaction and enhance interfacial stability. The dynamic degradation and surface regulation of SC‐NCM are investigated inside a working SSLB by in situ atomic force microscopy (AFM). We directly observe the uneven cathode electrolyte interphase (CEI) and surface defects on pristine SC‐NCM particle. Remarkably, the formed amorphous LiF‐rich CEI on L‐NCM maintains its initial structure upon cycling, and thus endows the battery with improved cycling stability and excellent rate capability. Such on‐site tracking provides deep insights into surface mechanism and structure–reactivity correlation of SC‐NCM, and thus benefits the optimizations of SSLBs.
Insights into the surface mechanism on the single‐crystalline LiNi0.5Co0.2Mn0.3O2 (SC‐NCM) cathode are disclosed by in situ atomic force microscopy in solid‐state batteries. Via atomic layer deposition, the Li3PO4 is introduced to coat SC‐NCM, leading to the uniform formation of LiF‐rich cathode electrolyte interphase and suppression of undesired side reaction, which endows batteries with enhanced interfacial stability, durability and dynamics.
Summary
Background
Hepatitis B virus (HBV) infection is a serious global health burden. TRIM26 has been reported to affect hepatitis C virus replication.
Aims
To manifest the role of TRIM26 on HBV ...replication and explore if there are single‐nucleotide polymorphisms (SNPs) in TRIM26 associated with response to pegylated interferon‐alpha (PegIFNα) treatment in patients with chronic hepatitis B (CHB).
Methods
We investigated the effect and mechanism of TRIM26 on HBV replication in vitro. The association between SNPs in TRIM26 and PegIFNα treatment response was evaluated in two independent cohorts including 238 and 707 patients with HBeAg‐positive CHB.
Results
Knockdown of TRIM26 increased, while overexpression of TRIM26 inhibited, HBV replication. Co‐immunoprecipitation assays and immunofluorescence showed that TRIM26 interacted and co‐localised with HBx. Co‐transfection of HBx‐HIS and TRIM26‐FLAG plasmids in Huh7 cells showed that TRIM26 inhibited the expression of HBx. Furthermore, TRIM26 inhibited HBV replication by mediating HBx ubiquitination degradation, and TRIM26 SPRY domain was responsible for the interaction and degradation of HBx. Besides, IFN increased TRIM26 expression. TRIM26 rs116806878 was associated with response to PegIFNα in two CHB cohorts. Moreover, a polygenic score integrating TRIM26 rs116806878, STAT4 rs7574865 and CFB rs12614 (previously reported to be associated with response to PegIFNα) was related to response to PegIFNα in CHB.
Conclusions
TRIM26 inhibits HBV replication; IFN promotes TRIM26 expression. TRIM26 exerts an inhibitory effect on HBx by promoting ubiquitin‐mediated degradation of HBx. Furthermore, TRIM26 rs116806878 is a potential predictive biomarker of response to PegIFNα in patients with CHB.
“TRIM26 inhibits HBV replication by promoting HBx degradation” and “TRIM26 rs116806878 predicts PegIFNα treatment response of HBeAg‐positive CHB patients".
Germanium is a promising high-capacity anode material for lithium ion batteries, but it usually exhibits poor cycling stability because of its huge volume variation during the lithium uptake and ...release process. A double protection strategy to improve the electrode performance of Ge through the use of Ge@C core–shell nanostructures and reduced graphene oxide (RGO) networks has been developed. The as-synthesized Ge@C/RGO nanocomposite showed excellent cycling performance and rate capability in comparison with Ge@C nanoparticles when used as an anode material for Li ion batteries, which can be attributed to the electronically conductive and elastic RGO networks in addition to the carbon shells and small particle sizes of Ge. The strategy is simple yet very effective, and because of its versatility, it may be extended to other high-capacity electrode materials with large volume variations and low electrical conductivities.
Background
As single-cell sequencing technology has been gradually introduced, it is essential to characterize global collaboration networks and map development trends over the past 20 years.
...Objective
The aim of this paper was to illustrate collaboration in the field of single-cell sequencing methods and explore key topics and future directions.
Methods
Bibliometric analyses were conducted with CiteSpace and VOSviewer software on publications prior to November 2019 from the Web of Science Core Collection about single-cell sequencing methods.
Results
Ultimately, we identified 2489 records, which were published in 495 journals by 14,202 authors from 1970 institutes in 61 countries. There was a noticeable increase in publications in 2014. The United States and high-income countries in Europe contributed to most of the records included. Harvard University, Stanford University, Karolinska Institutes, Peking University, and the University of Washington were the biggest nodes in every cluster of the collaboration network, and SA Teichmann, JC Marioni, A Regev, and FC Tang were the top-producing authors. Keywords co-occurrence analysis suggested applications in immunology as a developing research trend.
Conclusions
We concluded that the global collaboration network was unformed and that high-income countries contributed more to the rapidly growth of publications of single-cell sequencing technology. Furthermore, the application in immunology might be the next research hotspot and developmental direction.
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