Efficient pure-red perovskite light-emitting diodes with strong passivation via ultrasmall-sized molecules.

Perovskite light-emitting diodes (PeLEDs) have attracted great attention in recent years; however, the halogen vacancy defects in perovskite notably hamper the development of high-efficiency devices. Previously, large-sized passivation agents have been usually used, while the effect of defect passivation is limited due to the weak bonding or the large space steric hindrance. Here, we predict that the ultrasmall-sized formate (Fa) and acetate (Ac) have more efficient passivation ability because of the stronger binding with the perovskite, as demonstrated by density functional theory calculation. We introduce ultrasmall-sized cesium salts (CsFa/CsAc) into buried interface, which can also diffuse into the bulk, resulting in both buried interface and bulk passivation. In addition, the improved perovskite growth has been found due to the enhanced hydrophily after introducing CsFa/CsAc as additive. According to these advantages, a pure-red PeLED with 24.2% efficiency at 639 nm has been achieved.

Direct space-time manipulation mechanism for spatio-temporal coupling of ultrafast light field.

Traditionally, manipulation of spatiotemporal coupling (STC) of the ultrafast light fields can be actualized in the space-spectrum domain with some 4-f pulse shapers, which suffers usually from some limitations, such as spectral/pixel resolution and information crosstalk associated with the 4-f pulse shapers. This work introduces a novel mechanism for direct space-time manipulation of ultrafast light fields to overcome the limitations. This mechanism combines a space-dependent time delay with some spatial geometrical transformations, which has been experimentally proved by generating a high-quality STC light field, called light spring (LS). The LS, owing a broad topological charge bandwidth of 11.5 and a tunable central topological charge from 2 to -11, can propagate with a stable spatiotemporal intensity structure from near to far fields. This achievement implies the mechanism provides an efficient way to generate complex STC light fields, such as LS with potential applications in information encryption, optical communication, and laser-plasma acceleration.

The splicing factor Prpf31 is required for hematopoietic stem and progenitor cell expansion during zebrafish embryogenesis.

Pre-mRNA splicing is a precise regulated process and is crucial for system development and homeostasis maintenance. Mutations in spliceosomal components have been found in various hematopoietic malignancies (HMs) and have been considered as oncogenic derivers of HMs. However, the role of spliceosomal components in normal and malignant hematopoiesis remains largely unknown. Pre-mRNA processing factor 31 (PRPF31) is a constitutive spliceosomal component, which mutations are associated with autosomal dominant retinitis pigmentosa. PRPF31 was found to be mutated in several HMs, but the function of PRPF31 in normal hematopoiesis has not been explored. In our previous study, we generated a prpf31 knockout (KO) zebrafish line and reported that Prpf31 regulates the survival and differentiation of retinal progenitor cells by modulating the alternative splicing of genes involved in mitosis and DNA repair. In this study, by using the prpf31 KO zebrafish line, we discovered that prpf31 KO zebrafish exhibited severe defects in hematopoietic stem and progenitor cell (HSPC) expansion and its sequentially differentiated lineages. Immunofluorescence results showed that Prpf31-deficient HSPCs underwent malformed mitosis and M phase arrest during HSPC expansion. Transcriptome analysis and experimental validations revealed that Prpf31 deficiency extensively perturbed the alternative splicing of mitosis-related genes. Collectively, our findings elucidate a previously undescribed role for Prpf31 in HSPC expansion, through regulating the alternative splicing of mitosis-related genes.

A Spiking Artificial Vision Architecture Based on Fully Emulating the Human Vision.

Intelligent vision necessitates the deployment of detectors that are always-on and low-power, mirroring the continuous and uninterrupted responsiveness characteristic of human vision. Nonetheless, contemporary artificial vision systems attain this goal by the continuous processing of massive image frames and executing intricate algorithms, thereby expending substantial computational power and energy. In contrast, biological data processing, based on event-triggered spiking, has higher efficiency and lower energy consumption. Here, this work proposes an artificial vision architecture consisting of spiking photodetectors and artificial synapses, closely mirroring the intricacies of the human visual system. Distinct from previously reported techniques, the photodetector is self-powered and event-triggered, outputting light-modulated spiking signals directly, thereby fulfilling the imperative for always-on with low-power consumption. With the spiking signals processing through the integrated synapse units, recognition of graphics, gestures, and human action has been implemented, illustrating the potent image processing capabilities inherent within this architecture. The results prove the 90% accuracy rate in human action recognition within a mere five epochs utilizing a rudimentary artificial neural network. This novel architecture, grounded in spiking photodetectors, offers a viable alternative to the extant models of always-on low-power artificial vision system.

Synergistic π-Conjugation Organic Cathode for Ultra-Stable Aqueous Aluminum Batteries.

Rechargeable aqueous aluminum batteries (AABs) are promising energy storage technologies owing to their high safety and ultra-high energy-to-price ratio. However, either the strong electrostatic forces between high-charge-density Al3+ and host lattice, or sluggish large carrier-ion diffusion toward the conventional inorganic cathodes generates inferior cycling stability and low rate-capacity. To overcome these inherent confinements, a series of promising redox-active organic materials (ROMs) are investigated and a π-conjugated structure ROMs with synergistic C═O and C═N groups is optimized as the new cathode in AABs. Benefiting from the joint utilization of multi-redox centers and rich π-π intermolecular interactions, the optimized ROMs with unique ion coordination storage mechanism facilely accommodate complex active ions with mitigated coulombic repulsion and robust lattice structure, which is further validated via theoretical simulations. Thus, the cathode achieves enhanced rate performance (153.9 mAh g-1 at 2.0 A g-1 ) and one of the best long-term stabilities (125.7 mAh g-1 after 4,000 cycles at 1.0 A g-1 ) in AABs. Via molecular exploitation, this work paves the new direction toward high-performance cathode materials in aqueous multivalent-ion battery systems.

Automatic Chinese Food recognition based on a stacking fusion model.

With commercialization of deep learning models, daily precision dietary record based on images from smartphones becomes possible. This study took advantage of Deep-learning techniques on visual recognition tasks and proposed a big-data-driven Deep-learning model regressing from food images. We established the largest data set of Chinese dishes to date, named CNFOOD-241. It contained more than 190,000 images with 241 categories, covering Staple food, meat, vegetarian diet, mixed meat and vegetables, soups, dessert category. This study also compares the prediction results of three popular deep learning models on this dataset, ResNeXt101_32x32d achieving up to 82.05% for top-1 accuracy and 97.13% for top-5 accuracy. Besides, this paper uses a multi-model fusion method based on stacking in the field of food recognition for the first time. We built a meta-learner after the base model to integrate the three base models of different architectures to improve robustness. The accuracy achieves 82.88% for top-1 accuracy.Clinical Relevance-This study proves that the application of artificial intelligence technology in the identification of Chinese dishes is feasible, which can play a positive role in people who need to control their diet, such as diabetes and obesity.

The splicing factor DHX38 enables retinal development through safeguarding genome integrity.

DEAH-Box Helicase 38 (DHX38) is a pre-mRNA splicing factor and also a disease-causing gene of autosomal recessive retinitis pigmentosa (arRP). The role of DHX38 in the development and maintenance of the retina remains largely unknown. In this study, by using the dhx38 knockout zebrafish model, we demonstrated that Dhx38 deficiency causes severe differentiation defects and apoptosis of retinal progenitor cells (RPCs) through disrupted mitosis and increased DNA damage. Furthermore, we found a significant accumulation of R-loops in the dhx38-deficient RPCs and human cell lines. Finally, we found that DNA replication stress is the prerequisite for R-loop-induced DNA damage in the DHX38 knockdown cells. Taken together, our study demonstrates a necessary role of DHX38 in the development of retina and reveals a DHX38/R-loop/replication stress/DNA damage regulatory axis that is relatively independent of the known functions of DHX38 in mitosis control.

Single-cell RNA-sequencing analysis reveals enhanced non-canonical neurotrophic factor signaling in the subacute phase of traumatic brain injury.

BACKGROUND: Traumatic brain injury (TBI) is a leading cause of long-term disability in young adults and induces complex neuropathological processes. Cellular autonomous and intercellular changes during the subacute phase contribute substantially to the neuropathology of TBI. However, the underlying mechanisms remain elusive. In this study, we explored the dysregulated cellular signaling during the subacute phase of TBI. METHODS: Single-cell RNA-sequencing data (GSE160763) of TBI were analyzed to explore the cell-cell communication in the subacute phase of TBI. Upregulated neurotrophic factor signaling was validated in a mouse model of TBI. Primary cell cultures and cell lines were used as in vitro models to examine the potential mechanisms affecting signaling. RESULTS: Single-cell RNA-sequencing analysis revealed that microglia and astrocytes were the most affected cells during the subacute phase of TBI. Cell-cell communication analysis demonstrated that signaling mediated by the non-canonical neurotrophic factors midkine (MDK), pleiotrophin (PTN), and prosaposin (PSAP) in the microglia/astrocytes was upregulated in the subacute phase of TBI. Time-course profiling showed that MDK, PTN, and PSAP expression was primarily upregulated in the subacute phase of TBI, and astrocytes were the major source of MDK and PTN after TBI. In vitro studies revealed that the expression of MDK, PTN, and PSAP in astrocytes was enhanced by activated microglia. Moreover, MDK and PTN promoted the proliferation of neural progenitors derived from human-induced pluripotent stem cells (iPSCs) and neurite growth in iPSC-derived neurons, whereas PSAP exclusively stimulated neurite growth. CONCLUSION: The non-canonical neurotrophic factors MDK, PTN, and PSAP were upregulated in the subacute phase of TBI and played a crucial role in neuroregeneration.

Noninvasive Blood Glucose Monitoring Using Spatiotemporal ECG and PPG Feature Fusion and Weight-Based Choquet Integral Multimodel Approach.

change of blood glucose (BG) level stimulates the autonomic nervous system leading to variation in both human's electrocardiogram (ECG) and photoplethysmogram (PPG). In this article, we aimed to construct a novel multimodal framework based on ECG and PPG signal fusion to establish a universal BG monitoring model. This is proposed as a spatiotemporal decision fusion strategy that uses weight-based Choquet integral for BG monitoring. Specifically, the multimodal framework performs three-level fusion. First, ECG and PPG signals are collected and coupled into different pools. Second, the temporal statistical features and spatial morphological features in the ECG and PPG signals are extracted through numerical analysis and residual networks, respectively. Furthermore, the suitable temporal statistical features are determined with three feature selection techniques, and the spatial morphological features are compressed by deep neural networks (DNNs). Lastly, weight-based Choquet integral multimodel fusion is integrated for coupling different BG monitoring algorithms based on the temporal statistical features and spatial morphological features. To verify the feasibility of the model, a total of 103 days of ECG and PPG signals encompassing 21 participants were collected in this article. The BG levels of participants ranged between 2.2 and 21.8 mmol/L. The results obtained show that the proposed model has excellent BG monitoring performance with a root-mean-square error (RMSE) of 1.49 mmol/L, mean absolute relative difference (MARD) of 13.42%, and Zone A + B of 99.49% in tenfold cross-validation. Therefore, we conclude that the proposed fusion approach for BG monitoring has potentials in practical applications of diabetes management.

Retinal degeneration in rpgra mutant zebrafish.

Introduction: Pathogenic mutations in RPGR ORF15, one of two major human RPGR isoforms, were responsible for most X-linked retinitis pigmentosa cases. Previous studies have shown that RPGR plays a critical role in ciliary protein transport. However, the precise mechanisms of disease triggered by RPGR ORF15 mutations have yet to be clearly defined. There are two homologous genes in zebrafish, rpgra and rpgrb. Zebrafish rpgra has a single transcript homologous to human RPGR ORF15; rpgrb has two major transcripts: rpgrb ex1-17 and rpgrb ORF15, similar to human RPGR ex1-19 and RPGR ORF15, respectively. rpgrb knockdown in zebrafish resulted in both abnormal development and increased cell death in the dysplastic retina. However, the impact of knocking down rpgra in zebrafish remains undetermined. Here, we constructed a rpgra mutant zebrafish model to investigate the retina defect and related molecular mechanism. Methods: we utilized transcription activator-like effector nuclease (TALEN) to generate a rpgra mutant zebrafish. Western blot was used to determine protein expression. RT-PCR was used to quantify gene transcription levels. The visual function of embryonic zebrafish was detected by electroretinography. Immunohistochemistry was used to observe the pathological changes in the retina of mutant zebrafish and transmission electron microscope was employed to view subcellular structure of photoreceptor cells. Results: A homozygous rpgra mutant zebrafish with c.1675_1678delins21 mutation was successfully constructed. Despite the normal morphological development of the retina at 5 days post-fertilization, visual dysfunction was observed in the mutant zebrafish. Further histological and immunofluorescence assays indicated that rpgra mutant zebrafish retina photoreceptors progressively began to degenerate at 3-6 months. Additionally, the mislocalization of cone outer segment proteins (Opn1lw and Gnb3) and the accumulation of vacuole-like structures around the connecting cilium below the OSs were observed in mutant zebrafish. Furthermore, Rab8a, a key regulator of opsin-carrier vesicle trafficking, exhibited decreased expression and evident mislocalization in mutant zebrafish. Discussion: This study generated a novel rpgra mutant zebrafish model, which showed retinal degeneration. our data suggested Rpgra is necessary for the ciliary transport of cone-associated proteins, and further investigation is required to determine its function in rods. The rpgra mutant zebrafish constructed in this study may help us gain a better understanding of the molecular mechanism of retinal degeneration caused by RPGR ORF15 mutation and find some useful treatment in the future.

Systematic investigation of the mechanical, electronic, and interfacial properties of high mobility monolayer InAs from first-principles calculations.

Due to the excellent electrostatic control, high mobility, large specific surface area, and suitable direct energy gap of two-dimensional (2D) indium arsenide (InAs), it is regarded as one of the most promising alternative channel materials for next-generation electronic and optoelectronic devices. Recently, 2D semiconducting InAs has been successfully prepared. Based on first-principles calculations, we calculate the mechanical, electronic, and interfacial properties of monolayer (ML) fully-hydrogen-passivated InAs (InAsH2) material. The results show that 2D InAsH2 with excellent stability has a suitable logic device band gap (1.59 eV) comparable to silicon (1.14 eV) and 2D MoS2 (1.80 eV), and the electron carrier mobility of ML InAsH2 (490 cm2 V-1 s-1) is twice as large as that of 2D MoS2 (200 cm2 V-1 s-1). In addition, we study the electronic structure of the interfacial contact characteristics of ML half-hydrogen-passivated InAs (InAsH) with seven bulk metals (Ag, Au, Cu, Al, Ni, Pd, Pt) and two 2D metals (ML Ti2C and ML graphene). 2D InAs was metallized after contact with the seven bulk metals and two 2D metals. Based on the above, we insert 2D boron nitride (BN) between ML InAsH and the seven low/high-power function bulk metals to eliminate the interfacial states. Remarkably, the semiconducting properties of 2D InAs with Pd and Pt electrodes are recovered, and 2D InAs achieves p-type ohmic contact with the Pt electrode, which facilitates high on-current and high-frequency operation of the transistor. Hence, this work provides systematic theoretical guidance for the design of next-generation electronic devices.

Wafer-Scale Single Crystal Hexagonal Boron Nitride Layers Grown by Submicron-Spacing Vapor Deposition.

The direct growth of wafer-scale single crystal two-dimensional (2D) hexagonal boron nitride (h-BN) layer with a controllable thickness is highly desirable for 2D-material-based device applications. Here, for the first time, a facile submicron-spacing vapor deposition (SSVD) method is reported to achieve 2-inch single crystal h-BN layers with controllable thickness from monolayer to tens of nanometers on the dielectric sapphire substrates using a boron film as the solid source. In the SSVD growth, the boron film is fully covered by the same-sized sapphire substrate with a submicron spacing, leading to an efficient vapor diffusion transport. The epitaxial h-BN layer exhibits extremely high crystalline quality, as demonstrated by both a sharp Raman E2g vibration mode (12 cm-1 ) and a narrow X-ray rocking curve (0.10°). Furthermore, a deep ultraviolet photodetector and a ZrS2 /h-BN heterostructure fabricated from the h-BN layer demonstrate its fascinating properties and potential applications. This facile method to synthesize wafer-scale single crystal h-BN layers with controllable thickness paves the way to future 2D semiconductor-based electronics and optoelectronics.

Strain-Tunable Electronic and Transport Properties of One-Dimensional Fibrous Phosphorus Nanotubes.

The one-dimensional van der Waals (1D vdW) material fibrous red phosphorus (FRP) nanotubes are a promising direct-bandgap semiconductor with high carrier mobility and anisotropic optical responses because of low deformation potential and dangling-bond-free anisotropic interface. Employing first-principles calculations, we captured the potential of 1D FRP nanotubes. The thermal stability of 1D FRP nanotubes was confirmed by phonon calculation. Meanwhile, Raman spectroscopy indicated the strong vibration mode (366 cm-1) is along the phosphorus nanotube. Interestingly, spatial anisotropy bandgaps were found along with various stacking orientations. The charge transport calculations showed that the 1D FRP nanotube has a high hole mobility (499.2 cm2 V-1 s-1), considering the weak acoustic phonon scattering. More importantly, we found that the hole mobility changes dramatically (down to 7.1 cm2 V-1 s-1) under the strain, and the strain-dependent charge transport property of 1D FRP nanotubes could be considered to have many potential applications for electronics, optoelectronics, and switching devices.

Dark soliton families in quintic nonlinear lattices.

We prove that the dark solitons can be stable in the purely quintic nonlinear lattices, including the fundamental, tripole and five-pole solitons. These dark soliton families are generated on the periodic nonlinear backgrounds. The propagation constant affects the forms of these solitons, while the number of poles does not lead to the variation of the backgrounds. The dark solitons are stable only when the propagation constant is moderately large.

FISI: frequency domain integration sequential imaging at 1.26×1013 frames per second and 108 lines per millimeter.

High spatial resolution on the image plane (intrinsic spatial resolution) has always been a problem for ultrafast imaging. Single-shot ultrafast imaging methods can achieve high spatial resolution on the object plane through amplification systems but with low intrinsic spatial resolutions. We present frequency domain integration sequential imaging (FISI), which encodes a transient dynamic by an inversed 4f (IFF) system and decodes it using optical spatial frequencies recognition (OFR), which overcomes the limitation of the spatial frequencies recognition algorithm. In an experiment on the process of an air plasma channel, FISI achieved shadow imaging of the channel with a framing rate of 1.26×1013 fps and an intrinsic spatial resolution of 108 lp/mm (the spatial resolution on the image plane). Owing to its excellent framing time and high intrinsic spatial resolution, FISI can probe both repeatable and unrepeatable ultrafast phenomena, such as laser-induced damage, plasma physics, and shockwave interactions in living cells with high quality.

Elucidating the Gain Mechanism in PbS Colloidal Quantum Dot Visible-Near-Infrared Photodiodes.

The responsivities of colloidal quantum dot (CQD) photodiodes are not satisfactory (∼0.3 A W-1) due to the lack of gain. Here, visible-near-infrared PbS CQD photodiodes with a peak responsivity of ∼1 A W-1 and external quantum efficiencies larger than 100% are demonstrated. The gain is realized by electron tunneling injection through the Schottky junction (PbS-EDT/Au) with barrier height reduced to 0.27 eV, originating from the capture of photogenerated holes at the negatively charged acceptor traps generated in the oxidized hole-transport layer PbS-EDT. The resulting device exhibits a peak detectivity of ∼8 × 1011 jones at -1 V. Additionally, the response speed (400 µs) is not sacrificed by the trap states because of the dominated faster electron drift motion in the fully depleted device. Our results provide an accurate elucidation of the gain mechanism in CQD photodiodes and promise them great potential in weak light detection.

Dhx38 is required for the maintenance and differentiation of erythro-myeloid progenitors and hematopoietic stem cells by alternative splicing.

Mutations that occur in RNA-splicing machinery may contribute to hematopoiesis-related diseases. How splicing factor mutations perturb hematopoiesis, especially in the differentiation of erythro-myeloid progenitors (EMPs), remains elusive. Dhx38 is a pre-mRNA splicing-related DEAH box RNA helicase, for which the physiological functions and splicing mechanisms during hematopoiesis currently remain unclear. Here, we report that Dhx38 exerts a broad effect on definitive EMPs as well as the differentiation and maintenance of hematopoietic stem and progenitor cells (HSPCs). In dhx38 knockout zebrafish, EMPs and HSPCs were found to be arrested in mitotic prometaphase, accompanied by a 'grape' karyotype, owing to the defects in chromosome alignment. Abnormal alternatively spliced genes related to chromosome segregation, the microtubule cytoskeleton, cell cycle kinases and DNA damage were present in the dhx38 mutants. Subsequently, EMPs and HSPCs in dhx38 mutants underwent P53-dependent apoptosis. This study provides novel insights into alternative splicing regulated by Dhx38, a process that plays a crucial role in the proliferation and differentiation of fetal EMPs and HSPCs.

Electrically tunable two-dimensional heterojunctions for miniaturized near-infrared spectrometers.

Miniaturized spectrometers are of considerable interest for their portability. Most designs to date employ a photodetector array with distinct spectral responses or require elaborated integration of micro & nano optic modules, typically with a centimeter-scale footprint. Here, we report a design of a micron-sized near-infrared ultra-miniaturized spectrometer based on two-dimensional van der Waals heterostructure (2D-vdWH). By introducing heavy metal atoms with delocalized electronic orbitals between 2D-vdWHs, we greatly enhance the interlayer coupling and realize electrically tunable infrared photoresponse (1.15 to 1.47 µm). Combining the gate-tunable photoresponse and regression algorithm, we achieve spectral reconstruction and spectral imaging in a device with an active footprint < 10 µm. Considering the ultra-small footprint and simple fabrication process, the 2D-vdWHs with designable bandgap energy and enhanced photoresponse offer an attractive solution for on-chip infrared spectroscopy.

Red Perovskite Light-Emitting Diodes with Efficiency Exceeding 25% Realized by Co-Spacer Cations.

Perovskite light-emitting diodes (PeLEDs) have received great attention in recent years due to their narrow emission bandwidth and tunable emission spectrum. Efficient red emission is one of most important parts for lighting and displays. Quasi-2D perovskites can deliver high emission efficiency due to the strong carrier confinement, while the external quantum efficiencies (EQE) of red quasi-2D PeLEDs are inefficient at present, which is due to the complex distribution of different n-value phases in quasi-2D perovskite films. In this work, the phase distribution of the quasi-2D perovskite is finely controlled by mixing two different large organic cations, which effectively reduces the amount of smaller n-index phases, meanwhile the passivation of lead and halide defects in perovskite films is realized. Accordingly, the PeLEDs show 25.8% EQE and 1300 cd m-2 maximum brightness at 680 nm, which exhibits the highest performance for red PeLEDs up to now.

Limiting Factors of Detectivity in Near-Infrared Colloidal Quantum Dot Photodetectors.

Lead sulfide colloidal quantum dots (PbS CQDs) have shown great potential in photodetectors owing to their promising optical properties, especially their strong and tunable absorption. However, the limitation of the specific detectivity (D*) in CQD near-infrared (NIR) photodetectors remains unknown due to the ambiguous noise analysis. Therefore, a clear understanding of the noise current is critically demanded. Here, we elucidate that the noise current is the predominant factor limiting D*, and the noise is highly dependent on the trap densities in halide-passivated PbS films and the carriers injected from the Schottky contact (EDT-passivated PbS films/metal). It is found that the thickness of CQDs is proportional to their interface trap density, while it is inversely proportional to their minimal bulk trap density. A balance point can be reached at a certain thickness (136 nm) to minimize the trap density, giving rise to the improvement of D*. Utilizing thicker PbS-EDT films broadens the width of the tunneling barrier and thereby reduces the carrier injection, contributing to a further enhancement of D*. The limiting factors of D* determined in this work not only explain the physical mechanism of the influence on detection sensitivity but also give guidance to the design of high-performance CQD photodetectors.