An artificial visual neuron with multiplexed rate and time-to-first-spike coding.

Human visual neurons rely on event-driven, energy-efficient spikes for communication, while silicon image sensors do not. The energy-budget mismatch between biological systems and machine vision technology has inspired the development of artificial visual neurons for use in spiking neural network (SNN). However, the lack of multiplexed data coding schemes reduces the ability of artificial visual neurons in SNN to emulate the visual perception ability of biological systems. Here, we present an artificial visual spiking neuron that enables rate and temporal fusion (RTF) coding of external visual information. The artificial neuron can code visual information at different spiking frequencies (rate coding) and enables precise and energy-efficient time-to-first-spike (TTFS) coding. This multiplexed sensory coding scheme could improve the computing capability and efficacy of artificial visual neurons. A hardware-based SNN with the RTF coding scheme exhibits good consistency with real-world ground truth data and achieves highly accurate steering and speed predictions for self-driving vehicles in complex conditions. The multiplexed RTF coding scheme demonstrates the feasibility of developing highly efficient spike-based neuromorphic hardware.

Growth Factors-Loaded Temperature-Sensitive Hydrogel as Biomimetic Mucus Attenuated Murine Ulcerative Colitis via Repairing the Mucosal Barriers.

The pathogenesis of ulcerative colitis (UC) is associated with the shedding of the gut mucus. Herein, inspired by the biological functions of mucus, growth factors-loaded in situ hydrogel (PHE-EK) was designed for UC treatment by integrating dihydrocaffeic acid-modified poloxamer as a thermosensitive material with hyaluronic acid (colitis-specific adhesive), epigallocatechin-3-gallate (antibacterial agent), and bioactive factors (KPV tripeptide and epidermal growth factor). PHE-EK presented good thermosensitive properties, as a flowable liquid at room temperature and gelled within 10 s when exposed to body temperature. PHE-EK hydrogel presented good mechanical strength with a strain of 77.8%. Moreover, PHE-EK hydrogel displayed antibacterial activity against Escherichia coli. Importantly, in vitro and in vivo adhesive tests showed that the PHE-EK hydrogel could specifically adhere to the inflamed colon via electrostatic interaction. When PHE-EK as a biomimetic mucus was rectally administrated to colitis rats, it effectively hindered the body weight loss, reduced the disease activity index and improved the colonic shorting. Moreover, the expression of pro-inflammatory cytokines (e.g., IL-1ß, IL-6, and TNF-α) at the laminae propria or epitheliums of the colon for colitis rats was substantially inhibited by PHE-EK. Besides, the colonic epitheliums were well rearranged, and the tight junction proteins (Zonula-1 and Claudin-5) between them were greatly upregulated after PHE-EK treatment. Collectively, PHE-EK might be a promising therapy for UC.

Laser Direct Writing of Flexible Thermal Flow Sensors.

Thin film-based thermal flow sensors afford applications in healthcare and industries owing to their merits in preserving initial flow distributions. However, traditional thermal flow sensors are primarily applied to track flow intensities based on hot-wire or hot-film sensing mechanisms due to their relatively facile device configurations and fabrication strategies. Herein, a calorimetric thermal flow sensor is proposed based on laser direct writing to form laser-induced graphene as heaters and temperature sensors, resulting in monitoring both flow intensities and orientations. Via homogeneously surrounding spiral heaters with multiple temperature sensors, the device exhibits high sensitivity (∼162 K·s/m) at small flows with an extended flow detection range (∼25 m/s). Integrating the device with a data-acquisition board and a dual-mode graphical user interface enables wirelessly and dynamically monitoring respiration and the motion of robotic arms. This versatile flow sensor with facile manufacturing affords potentials in health inspection, remote monitoring, and studying hydrodynamics.

Enabling low-drift flexible perovskite photodetectors by electrical modulation for wearable health monitoring and weak light imaging.

Metal halide perovskites are promising for next-generation flexible photodetectors owing to their low-temperature solution processability, mechanical flexibility, and excellent photoelectric properties. However, the defects and notorious ion migration in polycrystalline metal halide perovskites often lead to high and unstable dark current, thus deteriorating their detection limit and long-term operations. Here, we propose an electrical field modulation strategy to significantly reduce the dark current of metal halide perovskites-based flexible photodetector more than 1000 times (from ~5 nA to ~5 pA). Meanwhile, ion migration in metal halide perovskites is effectively suppressed, and the metal halide perovskites-based flexible photodetector shows a long-term continuous operational stability (~8000 s) with low signal drift (~4.2 × 10-4 pA per second) and ultralow dark current drift (~1.3 × 10-5 pA per second). Benefitting from the electrical modulation strategy, a high signal-to-noise ratio wearable photoplethysmography sensor and an active-matrix photodetector array for weak light imaging are successfully demonstrated. This work offers a universal strategy to improve the performance of metal halide perovskites for wearable flexible photodetector and image sensor applications.

From the updated landscape of the emerging biologics for IBDs treatment to the new delivery systems.

Inflammatory bowel diseases (IBDs) treatments have shifted from small-molecular therapeutics to the oncoming biologics. The first-line biologics against the moderate-to-severe IBDs are mainly involved in antibodies against integrins, cytokines and cell adhesion molecules. Besides, other biologics including growth factors, antioxidative enzyme, anti-inflammatory peptides, nucleic acids, stem cells and probiotics have also been explored at preclinical or clinical studies. Biologics with variety of origins have their unique potentials in attenuating immune inflammation or gut mucosa healing. Great advances in use of biologics for IBDs treatments have been archived in recent years. But delivering issues for biologic have also been confronted due to their liable nature. In this review, we will focus on biologics for IBDs treatments in the recent publications; summarize the current landscapes of biologics and their promise to control disease progress. Alternatively, the confronted challenges for delivering biologics will also be analyzed. To combat these drawbacks, some new delivering strategies are provided: firstly, designing the functional materials with high affinity toward biologics; secondly, the delivering vehicle systems to encapsulate the liable biologics; thirdly, the topical adhering delivery systems as enema. To our knowledge, this review is the first study to summarize the updated usage of the oncoming biologics for IBDs, their confronted challenges in term of delivery and the potential combating strategies.

Bidirectional Synaptic Phototransistor Based on Two-Dimensional Ferroelectric Semiconductor for Mixed Color Pattern Recognition.

Optoelectronic synaptic devices capable of processing multiwavelength inputs are critical for neuromorphic vision hardware, which remains an important challenge. Here, we develop a bidirectional synaptic phototransistor based on a two-dimensional ferroelectric semiconductor of α-In2Se3, which exhibits bidirectional potentiated and depressed synaptic weight update under optical pulse stimulation. Importantly, the bidirectional optoelectronic synaptic behavior can be extended to multiwavelengths (blue, green, and red light), which could be used for color recognition. The mechanism underlying the bidirectional synaptic characteristics is attributed to the gate-configurable barrier heights as revealed by the Kelvin probe force microscopy measurement. The α-In2Se3 device exhibits versatile synaptic plasticity such as paired-pulse facilitation, short- and long-term potentiation, and long-term depression. The bidirectional optoelectronic synaptic weight updates under multiwavelength inputs enable a high accuracy of 97% for mixed color pattern recognition.

SCML2 contributes to tumor cell resistance to DNA damage through regulating p53 and CHK1 stability.

SCML2 has been found to be highly expressed in various tumors. However, the extent to which SCML2 is involved in tumorigenesis and cancer therapy is yet to be fully understood. In this study, we aimed to investigate the relationship between SCML2 and DNA damage response (DDR). Firstly, DNA damage stabilizes SCML2 through CHK1-mediated phosphorylation at Ser570. Functionally, this increased stability of SCML2 enhances resistance to DNA damage agents in p53-positive, p53-mutant, and p53-negative cells. Notably, SCML2 promotes chemoresistance through distinct mechanisms in p53-positive and p53-negative cancer cells. SCML2 binds to the TRAF domain of USP7, and Ser441 is a critical residue for their interaction. In p53-positive cancer cells, SCML2 competes with p53 for USP7 binding and destabilizes p53, which prevents DNA damage-induced p53 overactivation and increases chemoresistance. In p53-mutant or p53-negative cancer cells, SCML2 promotes CHK1 and p21 stability by inhibiting their ubiquitination, thereby enhancing the resistance to DNA damage agents. Interestingly, we found that SCML2A primarily stabilizes CHK1, while SCML2B regulates the stability of p21. Therefore, we have identified SCML2 as a novel regulator of chemotherapy resistance and uncovered a positive feedback loop between SCML2 and CHK1 after DNA damage, which serves to promote the chemoresistance to DNA damage agents.

Polydopamine-cladded montmorillonite micro-sheets as therapeutic platform repair the gut mucosal barrier of murine colitis through inhibiting oxidative stress.

Montmorillonite (MMT), a layered aluminosilicate, has a mucosal nutrient effect and restores the gut barriers integrity. However, orally administrating MMT is not effective to combat the reactive oxygen species (ROS) and alleviate the acute inflammatory relapse for colitis patients. Herein, polydopamine-doped montmorillonite micro-sheets (PDA/MMT) have been developed as a therapeutic platform for colitis treatment. SEM and EDS analysis showed that dopamine monomer (DA) was easily polymerized in alkaline condition and polydopamine (PDA) was uniformly cladded on the surface of MMT micro-sheets. The depositing amount of PDA was reaching to 2.06 â€‹± â€‹0.08%. Moreover, in vitro fluorescence probes experiments showed that PDA/MMT presented the broad spectra of scavenging various ROS sources including •OH, •O2-, and H2O2. Meanwhile, the intracellular ROS of Rosup/H2O2 treated Caco-2 â€‹cell was also effectively scavenged by PDA/MMT, which resulted in the obvious improvement of the cell viability under oxidative stress. Moreover, most of orally administrated PDA/MMT was transited to the gut and form a protective film on the diseased colon. PDA/MMT exhibited the obvious therapeutic effect on DSS-induced ulcerative colitis mouse. Importantly, the gut mucosa of colitis mouse was well restored after PDA/MMT treatment. Moreover, the colonic inflammation was significantly alleviated and the goblet cells were obliviously recovered. The therapeutic mechanism of PDA/MMT was highly associated with inhibiting oxidative stress. Collectively, PDA/MMT micro-sheets as a therapeutic platform may provide a promising therapeutic strategy for UC treatment.

Realizing nearly-zero dark current and ultrahigh signal-to-noise ratio perovskite X-ray detector and image array by dark-current-shunting strategy.

Although perovskite X-ray detectors have revealed promising properties, their dark currents are usually hundreds of times larger than the practical requirements. Here, we report a detector architecture with a unique shunting electrode working as a blanking unit to suppress dark current, and it theoretically can be reduced to zero. We experimentally fabricate the dark-current-shunting X-ray detector, which exhibits a record-low dark current of 51.1 fA at 5 V mm-1, a detection limit of 7.84 nGyair s-1, and a sensitivity of 1.3 × 104 µC Gyair-1 cm-2. The signal-to-noise ratio of our polycrystalline perovskite-based detector is even outperforming many previously reported state-of-the-art single crystal-based X-ray detectors by serval orders of magnitude. Finally, the proof-of-concept X-ray imaging of a 64 × 64 pixels dark-current-shunting detector array is successfully demonstrated. This work provides a device strategy to fundamentally reduce dark current and enhance the signal-to-noise ratio of X-ray detectors and photodetectors in general.

In situ polyphenol-adhesive hydrogel enhanced the noncarcinogenic repairing of KGF on the gut epithelial barrier on TNBS-induced colitis rats.

Ulcerative colitis (UC) is a chronic recurrent disease affecting the gastrointestinal tract especially colorectum. Keratinocyte growth factor (KGF) plays the vital roles in maintaining the colonic mucosal barrier. The poor stability and off-target of KGF were two hindering factors for its clinical application. Herein, in situ hydrogel (PE) with mucoadhesive ability was constructed by using temperature-sensitive poloxamer and EGCG as hydrogel-forming material and adhesive enhancer, respectively. Incorporation of EGCG led to the slight decrease of the gelled temperature and shortened the gelled time of PE hydrogel. When the concentration of EGCG is 0.1 %, PE hydrogel exhibits the suitable viscosity of 280 ± 20 Pa·s and the strong adhesive force of 725 ± 25 mN. KGF was soluble in cold PE solution to obtain KGF-loaded PE hydrogel (KGF@PE). PE hydrogel could improve the stability of KGF in vitro. KGF@PE not only could recover greatly the body weight of TNBS-induced rats but also repair their colonic morphology and goblet cell function. Moreover, the potential of repairing the epithelial barrier was indicated by upregulating tight junction proteins. Importantly, the safety of KGF@PE hydrogel for colitis was also confirmed on AOM/DSS-induced mice models. Conclusively, KGF@PE may be a promising therapeutic platform without obvious side effect for ulcerative colitis.

Highly Linear and Symmetric Synaptic Memtransistors Based on Polarization Switching in Two-Dimensional Ferroelectric Semiconductors.

Brain-inspired neuromorphic computing hardware based on artificial synapses offers efficient solutions to perform computational tasks. However, the nonlinearity and asymmetry of synaptic weight updates in reported artificial synapses have impeded achieving high accuracy in neural networks. Here, this work develops a synaptic memtransistor based on polarization switching in a two-dimensional (2D) ferroelectric semiconductor (FES) of α-In2 Se3 for neuromorphic computing. The α-In2 Se3 memtransistor exhibits outstanding synaptic characteristics, including near-ideal linearity and symmetry and a large number of programmable conductance states, by taking the advantages of both memtransistor configuration and electrically configurable polarization states in the FES channel. As a result, the α-In2 Se3 memtransistor-type synapse reaches high accuracy of 97.76% for digit patterns recognition task in simulated artificial neural networks. This work opens new opportunities for using multiterminal FES memtransistors in advanced neuromorphic electronics.

Inorganic-Organic Hybrid Phototransistor Array with Enhanced Photogating Effect for Dynamic Near-Infrared Light Sensing and Image Preprocessing.

Narrow-band-gap organic semiconductors have emerged as appealing near-infrared (NIR) sensing materials by virtue of their unique optoelectronic properties. However, their limited carrier mobility impedes the implementation of large-area, dynamic NIR sensor arrays. In this work, high-performance inorganic-organic hybrid phototransistor arrays are achieved for NIR sensing, by taking advantage of the high electron mobility of In2O3 and the strong NIR absorption of a BTPV-4F:PTB7-Th bulk heterojunction (BHJ) with an enhanced photogating effect. As a result, the hybrid phototransistors reach a high responsivity of 1393.0 A W-1, a high specific detectivity of 4.8 × 1012 jones, and a fast response of 0.72 ms to NIR light (900 nm). Meanwhile, an integrated 16 × 16 phototransistor array with a one-transistor-one-phototransistor (1T1PT) architecture is achieved. On the basis of the enhanced photogating effect, the phototransistor array can not only achieve real-time, dynamic NIR light mapping but also implement image preprocessing, which is promising for advanced NIR image sensors.

Fully Printed Optoelectronic Synaptic Transistors Based on Quantum Dot-Metal Oxide Semiconductor Heterojunctions.

Optoelectronic synaptic transistors with hybrid heterostructure channels have been extensively developed to construct artificial visual systems, inspired by the human visual system. However, optoelectronic transistors taking full advantages of superior optoelectronic synaptic behaviors, low-cost processes, low-power consumption, and environmental benignity remained a challenge. Herein, we report a fully printed, high-performance optoelectronic synaptic transistor based on hybrid heterostructures of heavy-metal-free InP/ZnSe core/shell quantum dots (QDs) and n-type SnO2 amorphous oxide semiconductors (AOSs). The elaborately designed heterojunction improves the separation efficiency of photoexcited charges, leading to high photoresponsivity and tunable synaptic weight changes. Under the coordinated modulation of electrical and optical modes, important biological synaptic behaviors, including excitatory postsynaptic current, short/long-term plasticity, and paired-pulse facilitation, were demonstrated with a low power consumption (∼5.6 pJ per event). The InP/ZnSe QD/SnO2 based artificial vision system illustrated a significantly improved accuracy of 91% in image recognition, compared to that of bare SnO2 based counterparts (58%). Combining the outstanding synaptic characteristics of both AOS materials and heterojunction structures, this work provides a printable, low-cost, and high-efficiency strategy to achieve advanced optoelectronic synapses for neuromorphic electronics and artificial intelligence.

Self-assembled peptides-modified flexible field-effect transistors for tyrosinase detection.

Flexible biosensors have received intensive attention for real-time, non-invasive monitoring of cancer biomarkers. Highly sensitive tyrosinase biosensors, which are important for melanoma screening, remained a hurdle. Herein, high-performance tyrosinase-sensing field-effect transistor-based biosensors (bio-FETs) have been successfully achieved by self-assembling nanostructured tetrapeptide tryptophan-valine-phenylalanine-tyrosine (WVFY) on n-type metal oxide transistors. In the presence of target tyrosinase, the phenolic hydroxyl groups in WVFY are rapidly converted to benzoquinone with the consumption of protons, which could be detected potentiometrically by bio-FETs. As a result, the WVFY-modified bio-FETs exhibited an ultra-low detection limit of 1.9 fM and an optimal detection range of 10 fM to 1 nM toward tyrosinase sensing. Furthermore, flexible devices fabricated on ∼2.9-µm-thick polyimide (PI) substrates illustrated robust mechanical flexibility, which could be attached to human skin conformally. These achievements hold promise for wearable melanoma screening and provide designing guidelines for detecting other important cancer biomarkers with bio-FETs.

Recombinant invasive Lactobacillus plantarum expressing the J subgroup avian leukosis virus Gp85 protein induces protection against avian leukosis in chickens.

Avian leukosis, caused by avian leukosis virus (ALV), is an infectious tumor disease and severely hinders the development of the poultry industry. The use of Lactobacillus plantarum (L. plantarum) could effectively alleviate viremia in the early period of J subgroup ALV (ALV-J) infection. In this study, an invasive L. plantarum NC8 expressing Gp85 protein of ALV-J was constructed. After chickens were orally administered the recombinant invasive NC8, the levels of expression of CD4+ and CD8+ T lymphocytes in peripheral blood and spleen by flow cytometry and the proliferation ability of splenocytes by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were examined, and the contents of cytokines, the anti-ALV-J antibody in serum, and mucosal antibody sIgA in intestinal lavage fluid were detected by enzyme-linked immunosorbent assay (ELISA). The immunoprotective efficiency was evaluated by monitoring the infection rate, the percent of cloacal swabs and survival, body weight gain, the organ indexes, and relative virus loads after challenge with ALV-J. The results showed that the recombinant invasive strain (FnBPA-gp85) could promote the expression levels of the CD8+T cells in peripheral blood and spleen, the proliferation of splenocytes, the secretions of cytokines interleukin 2 (IL-2) and γ-interferon (IFN-γ), and the production of IgG and sIgA compared with the PBS and FnBPA control groups in chickens. The FnBPA-gp85 group was exhibited the highest immune protection against ALV-J infection. The above results indicated that the recombinant invasive NC8 could promote the cellular immunity, humoral immunity, and mucosal immunity responses in chicken and provide a new method for exploring the live vaccine against ALV-J.Key points• The FnBPA-gp85 strain could enhance cellular immunity response.• The FnBPA-gp85 strain could improve the immune protection against ALV-J infection.

A Skin-Inspired Artificial Mechanoreceptor for Tactile Enhancement and Integration.

Mechanoreceptors endow humans with the sense of touch by translating the external stimuli into coded spikes, inspiring the rise of artificial mechanoreceptor systems. However, to incorporate slow adaptive receptors-like pressure sensors with artificial neurons remains a challenge. Here we demonstrate an artificial mechanoreceptor by rationally integrating a polypyrrole-based resistive pressure sensor with a volatile NbOx memristor, to mimic the tactile sensation and perception in natural skin, respectively. The artificial mechanoreceptor enables the tactile sensory coding by converting the external mechanical stimuli into strength-modulated electrical spikes. Also, tactile sensation enhancement is achieved by processing the spike frequency characteristics with the pulse coupled neural network. Furthermore, the artificial mechanoreceptor can integrate signals from parallel sensor channels and encode them into unified electrical spikes, resembling the coding of intensity in tactile neural processing. These results provide simple and efficient strategies for constructing future bio-inspired electronic systems.

Fully Printed High-Performance n-Type Metal Oxide Thin-Film Transistors Utilizing Coffee-Ring Effect.

Metal oxide thin-films transistors (TFTs) produced from solution-based printing techniques can lead to large-area electronics with low cost. However, the performance of current printed devices is inferior to those from vacuum-based methods due to poor film uniformity induced by the "coffee-ring" effect. Here, we report a novel approach to print high-performance indium tin oxide (ITO)-based TFTs and logic inverters by taking advantage of such notorious effect. ITO has high electrical conductivity and is generally used as an electrode material. However, by reducing the film thickness down to nanometers scale, the carrier concentration of ITO can be effectively reduced to enable new applications as active channels in transistors. The ultrathin (~10-nm-thick) ITO film in the center of the coffee-ring worked as semiconducting channels, while the thick ITO ridges (>18-nm-thick) served as the contact electrodes. The fully inkjet-printed ITO TFTs exhibited a high saturation mobility of 34.9 cm2 V-1 s-1 and a low subthreshold swing of 105 mV dec-1. In addition, the devices exhibited excellent electrical stability under positive bias illumination stress (PBIS, ΔVth = 0.31 V) and negative bias illuminaiton stress (NBIS, ΔVth = -0.29 V) after 10,000 s voltage bias tests. More remarkably, fully printed n-type metal-oxide-semiconductor (NMOS) inverter based on ITO TFTs exhibited an extremely high gain of 181 at a low-supply voltage of 3 V, promising for advanced electronics applications.

Flexible low-power source-gated transistors with solution-processed metal-oxide semiconductors.

Source-gated transistors (SGTs) with Schottky barriers have emerged as extraordinary candidates for constructing low-power electronics by virtue of device simplicity, high gain, and low operation voltages. In this work, we demonstrate flexible low-power SGTs with solution processed In2O3 channels and Al2O3 gate dielectrics on ultrathin polymer substrates, exhibiting light area density (0.56 mg cm-2), low subthreshold swing (102 mV dec-1), low operation voltage (<2 V), fast saturation behaviors (0.2 V), and low power consumption (46.3 µW cm-2). These achievements pave the way for employing the unconventional SGTs in wearable applications where low-power dissipation and high mechanical flexibility are essential.

Study on the Influencing Factors of Miners' Unsafe Behavior Propagation.

This study aims to explore the causes of unsafe behavior propagation (UBP) and then control the spread and prevalence of unsafe behavior in miners' social networks. Based on social learning theory, this study built a hypothetical model of correlation between safety atmosphere, safety knowledge, influence degree of key figures, and UBP. We administered an empirical study of an effective questionnaire from 433 miners in coal mines via structural equation modeling. The results showed that safety knowledge played a mediating role in the process of UBP influenced by safety atmosphere, and the influence degree of key figures also mediated the relationship between safety knowledge and UBP. Furthermore, the relation between safety atmosphere and UBP was sequentially mediated by safety knowledge and influence degree of key figures. Our research results provided new theoretical and methodological support for intervening in miners' unsafe behavior.