Search

Abstract Developing highly active materials that efficiently utilize solar spectra is crucial for photocatalysis, but still remains a challenge. Here, we report a new donor-acceptor (D-A) covalent organic framework (COF) with a wide absorption range from 200 nm to 900 nm (ultraviolet-visible-near infrared light). We find that the thiophene functional group is accurately introduced into the electron acceptor units of TpDPP-Py (TpDPP: 5,5’-(2,5-bis(2-ethylhexyl)−3,6-dioxo-2,3,5,6-tetrahydropyrrolo [3,4-c]pyrrole-1,4-diyl)bis(thiophene-2-carbaldehyde), Py: 1,3,6,8-tetrakis(4-aminophenyl)pyrene) COFs not only significantly extends its spectral absorption capacity but also endows them with two-photon and three-photon absorption effects, greatly enhancing the utilization rate of sunlight. The selective coupling of benzylamine as the target reactant is used to assess the photocatalytic activity of TpDPP-Py COFs, showing high photocatalytic conversion of 99% and selectivity of 98% in 20 min. Additionally, the TpDPP-Py COFs also exhibit the universality of photocatalytic selective coupling of other imine derivatives with ~100% conversion efficiency. Overall, this work brings a significant strategy for developing COFs with a wide absorption range to enhance photocatalytic activity.

Illicium simonsii Maxim (1888) is a medicinal species of the genus Illicium in the Illiciaceae family. It is commonly used to cure gastro-frigid vomiting, cystic hernia, gas pains in the chest, and scabies as folk medicine. To utilize its resources efficiently, the complete chloroplast genome of I. simonsii was sequenced, assembled, and annotated by using high-throughput sequencing data. The complete chloroplast genome was 143,038 bp in length, with a large single-copy region (LSC) of 101,094 bp, a short single-copy region (SSC) of 20,070 bp, and a pair of inverted repeats (IRs) of 21,874 bp. A total of 113 genes were annotated, including 79 protein-coding genes, 30 tRNA genes, and four rRNA genes. The phylogenetic tree exhibited that I. simonsii and Illicium burmanicum form a sister group, and were nested in the monophyletic clade of the Illicium genus.

Abstract Three-dimensional (3D) printing, otherwise known as additive manufacturing in a non-technical context, is becoming increasingly popular in the field of dentistry. As an essential step in the 3D printing process, postwashing with organic solvents can damage the printed resin polymer and possibly pose a risk to human health. The development of water-washable dental resins means that water can be used as a washing agent. However, the effects of washing agents and washing times on the mechanical and biocompatibility properties of water-washable resins remain unclear. This study investigated the impact of different washing agents (water, detergent, and alcohol) and washing time points (5, 10, 20, and 30 min) on the flexural strength, Vickers hardness, surface characterization, degree of conversion, biocompatibility, and monomer elution of 3D printed samples. Using water for long-term washing better preserved the mechanical properties, caused a smooth surface, and improved the degree of conversion, with 20 min of washing with water achieving the same biological performance as organic solvents. Water is an applicable agent option for washing the 3D printing water-washable temporary crown and bridge resin in the postwashing process. This advancement facilitates the development of other water-washable intraoral resins and the optimization of clinical standard washing guidelines.

Abstract Stretchable neuromorphic optoelectronics present tantalizing opportunities for intelligent vision applications that necessitate high spatial resolution and multimodal interaction. Existing neuromorphic devices are either stretchable but not reconcilable with multifunctionality, or discrete but with low-end neurological function and limited flexibility. Herein, we propose a defect-tunable viscoelastic perovskite film that is assembled into strain-insensitive quasi-continuous microsphere morphologies for intrinsically stretchable neuromorphic vision-adaptive transistors. The resulting device achieves trichromatic photoadaptation and a rapid adaptive speed (

Abstract Challenges associated with stretchable optoelectronic devices, such as pixel size, power consumption and stability, severely brock their realization in high-resolution digital imaging. Herein, we develop a universal detachable interface technique that allows uniform, damage-free and reproducible integration of micropatterned stretchable electrodes for pixel-dense intrinsically stretchable organic transistor arrays. Benefiting from the ideal heterocontact and short channel length (2 μm) in our transistors, switching current ratio exceeding 106, device density of 41,000 transistors/cm2, operational voltage down to 5 V and excellent stability are simultaneously achieved. The resultant stretchable transistor-based image sensors exhibit ultrasensitive X-ray detection and high-resolution imaging capability. A megapixel image is demonstrated, which is unprecedented for stretchable direct-conversion X-ray detectors. These results forge a bright future for the stretchable photonic integration toward next-generation visualization equipment.

Abstract Nanoclusters with atomically precise structures and discrete energy levels are considered as nanoscale semiconductors for artificial intelligence. However, nanocluster electronic engineering and optoelectronic behavior have remained obscure and unexplored. Hence, we create nanocluster photoreceptors inspired by mantis shrimp visual systems to satisfy the needs of compact but multi-task vision hardware and explore the photo-induced electronic transport. Wafer-scale arrayed photoreceptors are constructed by a nanocluster-conjugated molecule heterostructure. Nanoclusters perform as an in-sensor charge reservoir to tune the conductance levels of artificial photoreceptors by a light valve mechanism. A ligand-assisted charge transfer process takes place at nanocluster interface and it features an integration of spectral-dependent visual adaptation and circular polarization recognition. This approach is further employed for developing concisely structured, multi-task, and compact artificial visual systems and provides valuable guidelines for nanocluster neuromorphic devices.

Abstract Metal-nitrogen-carbon catalysts with hierarchically dispersed porosity are deemed as efficient geometry for oxygen reduction reaction (ORR). However, catalytic performance determined by individual and interacting sites originating from structural heterogeneity is particularly elusive and yet remains to be understood. Here, an efficient hierarchically porous Fe single atom catalyst (Fe SAs-HP) is prepared with Fe atoms densely resided at micropores and mesopores. Fe SAs-HP exhibits robust ORR performance with half-wave potential of 0.94 V and turnover frequency of 5.99 e−1s−1site−1 at 0.80 V. Theoretical simulations unravel a structural heterogeneity induced optimization, where mesoporous Fe-N4 acts as real active centers as a result of long-range electron regulation by adjacent microporous sites, facilitating O2 activation and desorption of key intermediate *OH. Multilevel operando characterization results identify active Fe sites undergo a dynamic evolution from basic Fe-N4 to active Fe-N3 under working conditions. Our findings reveal the structural origin of enhanced intrinsic activity for hierarchically porous Fe-N4 sites.

Control of the interfacial microstructures and mechanical properties of aluminum/steel joints after welding is crucial to prolonging the service lives of such structures. In this study, the influence of post-welding heat treatment (PWHT) on aluminum/steel laser-arc weld-brazing joints was investigated, with particular focus on the evolution mechanisms of the interfacial microstructures and regulation of the mechanical properties. Transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) results confirmed the presence of the monoclinic Fe4Al13 and hexagonal Al8Fe2Si phases at the aluminum/steel interface. Upon increasing the heat-treatment temperature, micro-characteristics of the intermetallic compound (IMC) passed through three different stages (weak elemental diffusion–reaction–drastic change) depending on the temperature employed; these stages differed from the PWHT phenomenon observed for the aluminum/steel solid-state welded joints. EBSD analyses revealed decreases in the grain size and textural strength of the IMC layer following PWHT at 180 °C/1 h, while the Fe4Al13 phase gradually transformed into Al8Fe2Si phase during PWHT at 520 °C/1 h, ultimately leading to an increase in the grain size and a higher textural strength. Additionally, PWHT effectively eliminated the residual tensile stress in aluminum/steel joints and improved the softening of the heat-affected zone (HAZ). Upon PWHT at 180 °C/1 h, the synergistic effects of the elimination of residual stress, an enhanced softening in the HAZ, and changes in the IMC layer, led to improved joint properties. Furthermore, the maximum tensile strengths of the joints with and without reinforcement increased to 221.9 MPa (from 209.8 MPa) and 165.3 MPa (from 148.1 MPa), respectively.

This study investigated the influence of Cd (25 µM) on Zn accumulation in a hyperaccumulating (HE) and a non-hyperaccumulating (NHE) ecotype of Sedum alfredii Hance at short-term supply of replete (Zn5, 5 µM) and excess (Zn400, 400 µM) Zn. Cd inhibited Zn accumulation in both ecotypes, especially under Zn400, in organs with active metal sequestration, i.e. roots of NHE and shoots of HE. Direct biochemical Cd/Zn competition at the metal-protein interaction and changes in transporter gene expression contributed to the observed accumulation patterns in the roots. Specifically, in HE, Cd stimulated SaZIP4 and SaPCR2 under Zn5, but downregulated SaIRT1 and SaZIP4 under Zn400. However, Cd downregulated related transporter genes, except for SaNRAMP1, in NHE, irrespective of Zn. Cadmium stimulated casparian strip (CSs) development in NHE, as part of the defense response, while it had a subtle effect on the (CS) in HE. Moreover, Cd delayed the initiation of the suberin lamellae (SL) in HE, but stimulated SL deposition in NHE under both Zn5 or Zn400. Changes in suberization were mainly ascribed to suberin-biosynthesis-related genes and hormonal signaling. Altogether, Cd regulated Zn accumulation mainly via symplasmic and transmembrane transport in HE, while Cd inhibited both symplasmic and apoplasmic Zn transport in NHE.

Public use and sharing of vector data while preserving its confidentiality is a critical challenge in geographic information security. Geometric accuracy reduction processing is commonly employed to process high-precision vector data containing a large amount of sensitive information into publicly available lower-precision data, which can balance the confidentiality and publicity of vector data. However, current research struggles to satisfy the security, controllability, and availability of processed data simultaneously. To address this issue, we propose a novel ellipsoid spatial mapping-based method for reducing the geometric accuracy of vector data. This method involves designing a model that utilizes Earth ellipsoid and spatial mapping techniques to safeguard vector data with irreversible offsets. We also develop offset variation functions for the x- and y-directions based on the model and predefined parameters, ensuring the availability and controllability of the processed data. Experimental results indicate that our method satisfies controllable accuracy reduction requirements, preserves the significant majority of shape and topology of the original data, and provides faster processing speeds compared to other methods. Our method ensures that processed data complies with confidentiality regulations, promoting the broader application of vector data.

Laser–MIG hybrid welding–brazing was used to weld 304 stainless steel and 6061-T6 aluminum alloy with a thickness of 2 mm. The microstructure, morphology, chemical composition and corrosion behavior of the samples after high-temperature oxidation were investigated. The results reveal that the 304/6061 dissimilar joint had a thicker intermetallic compound layer (7–8 μm) during high-temperature oxidation (HTO) treatment than the sample without HTO treatment (2–3 μm). The oxide film thickness of the 6061 side of the weld joint treated by HTO (2401 nm) increased compared to the samples (181.1 nm) without HTO treatment. Unlike other metals treated by high-temperature oxidation, the high-temperature treatment process in this paper can reduce the corrosion resistance of the base metal and dissimilar joints, and the sequence of the corrosion current density was weld (HTO) >weld>6061 (HTO) >6061>304 (HTO) >304.