A defect-enriched PdMo bimetallene for ethanol oxidation reaction and 4-nitrophenol reduction.

A defect-enriched PdMo bimetallene (d-PdMo) was prepared by a one-pot wet chemical reaction followed by post-treatment of oxidative etching. The introduction of defects can tailor the electronic structure of PdMo bimetallene and the prepared d-PdMo bimetallene exhibited excellent performance in the ethanol oxidation reaction (EOR) and 4-nitrophenol (4-NP) reduction reaction.

Enhancing Overall Water Splitting via Anion and Cation Synergistical Modulation in NiS Amorphous Compound.

Designing and synthesizing cost-effective catalysts that exhibit excellent performance of both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is a formidable task in the field of electrocatalysis. Herein, we present a Fe- and P-codoped NiS amorphous film catalyst (FeNiSP) via meticulous control over the cations and anions of metal compounds. The doped Fe and P increases active sites, reduces charge transfer resistance, and modulates electronic structures of the NiS matrix. Leveraging these advantages, the FeNiSP showcases exceptional bifunctional activities of HER and OER, with remarkably low overpotentials of only 135 and 330 mV for achieving a current density of 100 mA·cm-2 during HER and OER, respectively. Additionally, a low cell voltage of 1.56 V at 10 mA·cm-2 was achieved when it was employed as both the anode and the cathode for water splitting. Finally, density function theory calculations further elucidate that the simultaneous presence of Fe and P in the NiS amorphous film catalyst leads to a decrease in the band center of S and Ni. This consequential effect maintains a balanced adsorption/desorption of protons and strengthened the adsorption of O-based intermediates on the surface of FeNiSP, subsequently contributing to the outstanding electrocatalytic HER and OER activities.

Construction of PCL-collagen@PCL@PCL-gelatin three-layer small diameter artificial vascular grafts by electrospinning.

The demand for artificial vascular grafts in clinical applications is increasing, and it is urgent to design a tissue-engineered vascular graft with good biocompatibility and sufficient mechanical strength. In this study, three-layer small diameter artificial vascular grafts were constructed by electrospinning. Polycaprolactone (PCL) and collagen (COL) were used as the inner layer to provide good biocompatibility and cell adhesion, the middle layer was PCL to improve the mechanical properties, and gelatin (GEL) and PCL were used to construct the outer layer for further improving the mechanical properties and biocompatibility of the vascular grafts in the human body environment. The electrospun artificial vascular graft had good biocompatibility and mechanical properties. Its longitudinal maximum stress reached 2.63 ± 0.12 MPa, which exceeded the maximum stress that many natural blood vessels could withstand. The fiber diameter of the vascular grafts was related to the proportion of components that made up the vascular grafts. In the inner structure of the vascular grafts, the hydrophilicity of the vascular grafts was enhanced by the addition of COL to the PCL, and human umbilical vein endothelial cells (HUVECs) adhered more easily to the vascular grafts. In particular, the cytocompatibility and proliferation of HUVECs on the scaffold with an inner structure PCL:COL = 2:1 was superior to other ratios of vascular grafts. The vascular grafts did not cause hemolysis of red blood cells. Thus, the bionic PCL-COL@PCL@PCL-GEL composite graft is a promising material for vascular tissue engineering.

Fabrication of FA/HA-functionalized carbon dots for human breast cancer cell targeted imaging.

Green fluorescent carbon dots (CDs) were prepared by one-step hydrothermal method and then modified into folic acid functionalized carbon dots (FA-CDs) and hyaluronic acid functionalized carbon dots (HA-CDs) with targeted function to study their application in breast cancer cells imaging. The microstructure of the CDs observed through TEM showed the CDs with a scale of 2.69 nm. FT-IR and XPS showed the changes of bonds and functional groups that confirmed the transformation of COOH and NH2 to amide bonds. FA-CDs and HA-CDs had good water solubility and cytocompatibility, which laid a foundation for their application in human breast cancer cells imaging. At the same time, FA-CDs and HA-CDs had strong fluorescence excitation, and the optimal emission wavelength was about 450 nm. In fluorescence imaging of cells, carbon dots had bright green fluorescence in both breast cancer cells (MCF-7 cells) and normal cells (EC cells). After targeted endocytosis, FA-CDs and HA-CDs could emit bright green fluorescence in cancer cells but could not in normal cells, which proved that the synthesized FA-CDs and HA-CDs had targeting properties. FA-CDs and HA-CDs could be used to accurately identify breast cancer cells and normal cells as cancer diagnosis material, which had the potential application in early cancer diagnosis.

Tasseled Crop Rows Detection Based on Micro-Region of Interest and Logarithmic Transformation.

Machine vision-based navigation in the maize field is significant for intelligent agriculture. Therefore, precision detection of the tasseled crop rows for navigation of agricultural machinery with an accurate and fast method remains an open question. In this article, we propose a new crop rows detection method at the tasseling stage of maize fields for agrarian machinery navigation. The whole work is achieved mainly through image augment and feature point extraction by micro-region of interest (micro-ROI). In the proposed method, we first augment the distinction between the tassels and background by the logarithmic transformation in RGB color space, and then the image is transformed to hue-saturation-value (HSV) space to extract the tassels. Second, the ROI is approximately selected and updated using the bounding box until the multiple-region of interest (multi-ROI) is determined. We further propose a feature points extraction method based on micro-ROI and the feature points are used to calculate the crop rows detection lines. Finally, the bisector of the acute angle formed by the two detection lines is used as the field navigation line. The experimental results show that the algorithm proposed has good robustness and can accurately detect crop rows. Compared with other existing methods, our method's accuracy and real-time performance have improved by about 5 and 62.3%, respectively, which can meet the accuracy and real-time requirements of agricultural vehicles' navigation in maize fields.

Preparation and biological properties of ZnO/hydroxyapatite/chitosan-polyethylene oxide@gelatin biomimetic composite scaffolds for bone tissue engineering.

To imitate the composition of natural bone and further improve the biological property of the materials, ZnO/hydroxyapatite/chitosan-polyethylene oxide@gelatin (ZnO/HAP/CS-PEO@GEL) composite scaffolds were developed. The core-shell structured chitosan-polyethylene oxide@gelatin (CS-PEO@GEL) nanofibers which could form the intramolecular hydrogen bond and achieve an Arg-Gly-Asp (RGD) polymer were first prepared by coaxial electrospinning to mimic the extracellular matrix. To further enhance biological activity, hydroxyapatite (HAP) was grown on the surface of the CS-PEO@GEL nanofibers using chemical deposition and ZnO particles were then evenly distributed on the surface of the above composite materials using RF magnetron sputtering. The SEM results showed that chemical deposition and magnetron sputtering did not destroy the three-dimensional architecture of materials, which was beneficial to cell growth. The cell compatibility and proliferation of MG-63 cells on ZnO/HAP/CS-PEO@GEL composite scaffolds were superior to those on CS-PEO@GEL and HAP/CS-PEO@GEL composite scaffolds. An appropriate amount of ZnO sputtering could promote the adhesion of cells on the composite nanofibers. The structure of bone tissue could be better simulated both in composition and in the microenvironment, which provided a suitable environment for cell growth and promoted the proliferation of MG-63 cells. The biomimetic ZnO/HAP/CS-PEO@GEL composite scaffolds were promising materials for bone tissue engineering.

A neural decoding algorithm that generates language from visual activity evoked by natural images.

Transforming neural activities into language is revolutionary for human-computer interaction as well as functional restoration of aphasia. Present rapid development of artificial intelligence makes it feasible to decode the neural signals of human visual activities. In this paper, a novel Progressive Transfer Language Decoding Model (PT-LDM) is proposed to decode visual fMRI signals into phrases or sentences when natural images are being watched. The PT-LDM consists of an image-encoder, a fMRI encoder and a language-decoder. The results showed that phrases and sentences were successfully generated from visual activities. Similarity analysis showed that three often-used evaluation indexes BLEU, ROUGE and CIDEr reached 0.182, 0.197 and 0.680 averagely between the generated texts and the corresponding annotated texts in the testing set respectively, significantly higher than the baseline. Moreover, we found that higher visual areas usually had better performance than lower visual areas and the contribution curve of visual response patterns in language decoding varied at successively different time points. Our findings demonstrate that the neural representations elicited in visual cortices when scenes are being viewed have already contained semantic information that can be utilized to generate human language. Our study shows potential application of language-based brain-machine interfaces in the future, especially for assisting aphasics in communicating more efficiently with fMRI signals.

A dual-channel language decoding from brain activity with progressive transfer training.

When we view a scene, the visual cortex extracts and processes visual information in the scene through various kinds of neural activities. Previous studies have decoded the neural activity into single/multiple semantic category tags which can caption the scene to some extent. However, these tags are isolated words with no grammatical structure, insufficiently conveying what the scene contains. It is well-known that textual language (sentences/phrases) is superior to single word in disclosing the meaning of images as well as reflecting people's real understanding of the images. Here, based on artificial intelligence technologies, we attempted to build a dual-channel language decoding model (DC-LDM) to decode the neural activities evoked by images into language (phrases or short sentences). The DC-LDM consisted of five modules, namely, Image-Extractor, Image-Encoder, Nerve-Extractor, Nerve-Encoder, and Language-Decoder. In addition, we employed a strategy of progressive transfer to train the DC-LDM for improving the performance of language decoding. The results showed that the texts decoded by DC-LDM could describe natural image stimuli accurately and vividly. We adopted six indexes to quantitatively evaluate the difference between the decoded texts and the annotated texts of corresponding visual images, and found that Word2vec-Cosine similarity (WCS) was the best indicator to reflect the similarity between the decoded and the annotated texts. In addition, among different visual cortices, we found that the text decoded by the higher visual cortex was more consistent with the description of the natural image than the lower one. Our decoding model may provide enlightenment in language-based brain-computer interface explorations.

Hyaluronic acid conjugated nitrogen-doped graphene quantum dots for identification of human breast cancer cells.

Accurate distinguish of cancer cells through fluorescence plays an important role in cancer diagnosis. Here we synthesized a blue fluorescent nitrogen-doped graphene quantum dots (N-GQDs) from citric acid and diethylamine via one-step hydrothermal synthesis method which was simple and quick to avoid by-products, and highlighted the binding sites to achieve precise combination. Due to the nitrogen element doping, amide II bond was amply obtained and abundant binding sites were provided for hyaluronic acid (HA) conjugation. N-GQDs solution with different pH value was then conjugated to HA via an amide bond for the recognition of human breast cancer cells (MCF-7 cells), and the formation of amide bond was more favorable under alkaline conditions. HA conjugated N-GQDs (HA-N-GQDs) were combined with CD44 which was over expressed on the surface of MCF-7 cells, resulting in MCF-7 cells performing stronger fluorescence. HA-N-GQDs showed high fluorescence, low toxicity, and good cytocompatibility, which held it play a role in fluorescence imaging for accurate identification of cancer cells.

Tracing the ionic evolution during ILG induced phase transformation in strontium cobaltite thin films.

Ionic liquid gating (ILG) that drives the ions incorporate into or extract from the crystal lattice, has emerged as a new pathway to design materials. Although many intriguing emergent phenomena, novel physical properties and functionalities have been obtained, the gating mechanism governing the ion and charge transport remains unexplored. Here, by using the model system of brownmillerite SrCoO2.5 and the corresponding electric-field controlled tri-state phase transformation among the pristine SrCoO2.5, hydrogenated HSrCoO2.5 and oxidized perovskite SrCoO3-δ through the dual ion switch, the ionic diffusion and electronic transport processes were carefully investigated. Through controlling gating experiment by design, we find out that the collaborative interaction between charge transport and ion diffusion plays an essential role to prompt the hydrogen or oxygen ions incorporate into the crystal lattice of SrCoO2.5, and therefore leading to formation of new phases. At region closer to the electrode, the electron can shuttle more readily in (out) the material, correspondingly the incorporation of hydrogen (oxygen) ions and phase transformation is largely affiliated. With the compensated charge of electron as well as the reaction front gradually moving away from the electrode, the new phases would be developed successively across the entire thin film. This result unveils the underlying mechanism in the electric-field control of ionic incorporation and extraction, and therefore provides important strategy to achieve high efficient design of material functionalities in complex oxide materials.

Enhanced photocatalytic hydrogen production of MoS2 sheet/carbon nanofiber using rapid electron transport of Mo6+ and carbon nanofiber.

Normal MoS2 exhibits a low photocatalytic performance for H2 production owing to the deficiency of the active sites and the poor electrical conductance. In this work, MoS2 anchored on the surface of the carbon nanofibers was designed to enhance the activity of the exposed edge and the electrical conductivity at the same time. The oxidation of the surface Mo atoms increases the activity of the exposed edge of the MoS2. The introduction of carbon nanofibers facilitates the effective transportation of the electron-hole pairs by enhancing the electrical conductivity. As a result, the introduction of carbon nanofibers and Mo6+ can facilitate the electron-hole pair separation to enhance the photocatalytic hydrogen evolution reaction (HER) performance (to eight fold more than normal MoS2).

Improved charge injection of edge aligned MoS2/MoO2 hybrid nanosheets for highly robust and efficient electrocatalysis of H2 production.

Molybdenum disulfide (MoS2) can be an efficient electro-catalyst for the hydrogen evolution reaction (HER) as an alternative to precious metals, but significant efforts are still needed to further improve its efficiency. Among various approaches, the formation of edge aligned MoS2 on an electrically conductive support is highly promising for cost-effective H2 production. Nevertheless, catalysis is highly impeded by the poor charge transport between the electrode materials and also between the multilayers of MoS2. This research presents a strategy to improve the HER catalysis by binding layers of metallic molybdenum dioxide (MoO2) and MoS2 to form hybrid MoS2/MoO2 nanosheets (attached and cross-linked to each other). Taking advantage of the hybrid structure and the mechanical strength of the carbon cloth, a catalyst with outstanding catalytic performance in the HER is demonstrated. This work shows not only a strategy to efficiently improve the electrochemical process, but also the preparation of a highly efficient catalyst for constant and robust H2 production.

Phase junction enhanced photocatalytic activity of Ga2O3 nanorod arrays on flexible glass fiber fabric.

Ga2O3 nanostructures hold great potential applications in photocatalytic fields due to their stability, high efficiency and environmental friendliness. The construction of phase junction has been proved to be one of the most effective strategies for enhancing Ga2O3 photocatalytic activity. However, the influence of the formation process at the interface of the phase junction on the photocatalytic activity of Ga2O3 nanostructures is far less well understood. In this work, for the first time, large-area Ga2O3 nanorod arrays (NRAs) with controllable α/ß phase junction were prepared in situ on a flexible glass fiber fabric by a facile and environmentally friendly three-step method. The α/ß-Ga2O3 phase junction NRAs exhibit an ultra-high photocatalytic degradation rate of 97% during Ultraviolet (UV) irradiation for 60 min, which is attributed to a unique phase junction promoting efficient charge separation. However, the photocatalytic activity of α/ß-Ga2O3 phase junction NRAs is not evident in the early phase transition, possibly due to the presence of defects acting as charge recombination centers.

Folic acid-conjugated nitrogen-doped graphene quantum dots as a fluorescent diagnostic material for MCF-7 cells.

This paper reports the preparation and application of folic acid-conjugated nitrogen-doped graphene quantum dots (N-GQDs) as a fluorescent diagnostic material for MCF-7 cells of breast cancer. N-GQDs were prepared by a hydrothermal method using citric acid as the carbon source and diethylamine as the nitrogen source. The doping of different amounts of nitrogen content was effectively controlled by diethylamine. As the amount of nitrogen increased, more binding sites on the N-GQDs were supplied to the folic acid. Laser confocal scanning microscopy showed that increased folic acid binding facilitated the recognition of and entry to cancer cells, which made the labeled cells emit a stronger fluorescence and thus the cancer cells could be better detected. Cytotoxicity tests showed that the material was of low cytotoxicity, making it a promising prospect for fluorescent probes.

Efficient Water Transport and Solar Steam Generation via Radially, Hierarchically Structured Aerogels.

A nature-inspired water-cycling system, akin to trees, to perform effective water and solar energy management for photosynthesis and transpiration is considered to be a promising strategy to solve water scarcity issues globally. However, challenges remain in terms of the relatively low transport rate, short transport distance, and unsatisfactory extraction efficiency. Herein, enlightened by conifer tracheid construction, an efficient water transport and evaporation system composed of a hierarchical structured aerogel is reported. This architecture with radially aligned channels, micron pores, and molecular meshes is realized by applying a radial ice-template method and in situ cryopolymerization technique. This nature-inspired design benefits the aerogel excellent capillary rise performance, realizing a long-distance (>28 cm at 190 min) and quick (>1 cm at 1 s, >9 cm at 300 s) antigravity water transport on a macroscopic scale, regardless of clean water, seawater, sandy groundwater, or dye-including effluent. Furthermore, an efficient water transpiration and collection is performed by the bilayer-structured aerogel with a carbon heat collector on an aerogel top, demonstrating a solar steam generation rate of 2.0 kg m-2 h-1 with the energy conversion efficiency up to 85.7% under one solar illumination. This biomimetic design with the advantage of water transport and evaporation provides a potential approach to realize water purification, regeneration, and desalination.

Biomimetic composite scaffold of hydroxyapatite/gelatin-chitosan core-shell nanofibers for bone tissue engineering.

Good biocompatibility and osteogenesis of three-dimensional porous scaffolds are critical for bone tissue engineering. In this work, biomimetic hydroxyapatite/gelatin-chitosan core-shell nanofibers composite scaffolds have been fabricated to mimic both the specific structure and the chemical composition of natural bone. The coaxial electrospinning technique was introduced to prepare gelatin-chitosan core-shell structured nanofibers mat which formed three-dimensional porous structure for promoting cells growth. The gelatin-chitosan core-shell nanofibers formed Arginine-Glycine-Aspartic acid (RGD)-like structure to mimic the organic component of natural bone extracellular matrix. Hydroxyapatite (Ca10(PO4)6(OH)2, HAP), as the major mineral constituent of native bone, was then deposited onto the surface of gelatin-chitosan core-shell structured nanofibers by a wet chemical method. Compared with chitosan nanofibers, gelatin nanofibers and chitosan-gelatin composite nanofibers, gelatin-chitosan core-shell structured nanofibers improved the mineralization efficiency of hydroxyapatite and formed a homogeneous HAP deposit. When Human osteoblast like cell line (MG-63) were cultured on the materials, the results showed that hydroxyapatite deposited on the gelatin-chitosan core-shell structured nanofibers could further enhance osteoblast cell proliferation. The biomimetic composite scaffolds could be suggested as a promising material to promote osteoblast cell growth in bone tissue engineering.

Dispersing gold nanoparticles on thiolated polyaniline-multiwalled carbon nanotubes for development of an indole-3-acetic acid amperometric immunosensor.

An amperometric immunosensor based on new thiolated bionanocomposite with a high dispersion of gold nanoparticles (AuNPs) for the sensitive detection of indole-3-acetic acid (IAA) is being reported herein. Briefly, a thiolated nanocomposite was prepared via the microwave-assisted thiol-ene reaction of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) with oxidized polyaniline (PANI), which was synthesized in the presence of multiwalled carbon nanotubes (MWCNTs), yielding thiolated polyaniline (TPANI)-MWCNTs. Further, AuNPs were deposited on the TPANI-MWCNTs by microwave-assisted method to obtain a AuNPs/TPANI-MWCNTs nanocomposite. Finally, the thiolated bionanocomposite film was constructed via the specific chemical reaction between boronic acid functionalized AuNPs and the vicinal diol functionalized AuNP labeled immunoglobulin G (IgG-AuNPs). The change in the reduction peak current of Fe(CN)6 3- was used to monitor the immunoreaction between IAA and antibody. The TPANI-MWCNT nanocomposites uniformly disperse AuNPs, IgG-AuNPs and anti-IAA-AuNPs, leading to the amplification of the signal of the immunosensor. Fourier transform infrared spectra (FTIR), cyclic voltammetry (CV), transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV-vis) and differential pulse voltammetry (DPV) were used to characterize the nanocomposite film and the stepwise modification of the immunosensor. The prepared thiolated bionanocomposite material has good biocompatibility, a highly uniform dispersion of the AuNPs with a narrow size distribution as verified by TEM, and high load/activity of the immobilized antibody proved via DPV. The fabricated IAA amperometric immunosensor not only exhibits a good linear arrange from 1.0 pg mL-1 to 10 ng mL-1 with the limit of detection of 0.97 pg mL-1 (S/N = 3), but also possesses good selectivity, reproducibility and stability for the detection of IAA.

Self-Powered Ultraviolet Photodetector with Superhigh Photoresponsivity (3.05 A/W) Based on the GaN/Sn:Ga2O3 pn Junction.

Ultraviolet (UV) radiation has a variety of impacts including the health of humans, the production of crops, and the lifetime of buildings. Based on the photovoltaic effect, self-powered UV photodetectors can measure and monitor UV radiation without any power consumption. However, the current low photoelectric performance of these detectors has hindered their practical use. In our study, a super-high-performance self-powered UV photodetector based on a GaN/Sn:Ga2O3 pn junction was generated by depositing a Sn-doped n-type Ga2O3 thin film onto a p-type GaN thick film. The responsivity at 254 nm reached up to 3.05 A/W without a power supply and had a high UV/visible rejection ratio of R254 nm/ R400 nm = 5.9 × 103 and an ideal detectivity at 1.69 × 1013 cm·Hz1/2·W-1, which is well beyond the level of previous self-powered UV photodetectors. Moreover, our device also has a low dark current (1.8 × 10-11A), a high Iphoto/ Idark ratio (∼104), and a fast photoresponse time of 18 ms without bias. These outstanding performance results are attributed to the rapid separation of photogenerated electron-hole pairs driven by a high built-in electric field in the interface depletion region of the GaN/Sn:Ga2O3 pn junction. Our results provide an improved and easy route to constructing high-performance self-powered UV photodetectors that can potentially replace traditional high-energy-consuming UV detection systems.

Proximity exchange induced gap opening and topological feature in graphene/1T'-MX2 (M = Mo,W; X = S,Se,Te) Dirac heterostructures.

By using first-principles calculations, we demonstrate the influence of proximity effect on the band structures of heterostructures formed by graphene stacking on a two dimensional (2D) topological insulator (TI) 1T'-MX2. The interlayer distance d between graphene and TI decreases with the enhancement of the intrinsic lattice anisotropy of 1T'-MX2, which determines different strength of the interlayer proximity interaction. The bandgap can be opened by the proximity exchange. The weak anisotropic symmetry of heterostructure (large d) only results in a small band gap (∼50 meV) in graphene/MoTe2. However, a large energy gap (up to ∼200 meV) can be obtained in graphene/MoS2, which is attributed to the inter-intralayer charge transfer due to the strong proximity interaction of the hetero-interface (small d). In addition, the 1T'-MX2 of heterostructure still possesses the topological feature of Z 2 = 1, since the graphene has a negligible effect on the band structure of the system.

Evolution of local wrinkles near defects on stiff film/compliant substrate.

Disordered wrinkles are widely observed in stiff film deposited onto a thermally expanded polymer when compressive stress exceeds the critical wrinkling stress of the film. Highly ordered wrinkles can be fabricated by introducing regularly arranged patterns on the polymer before deposition. However, the study on the morphological evolution of localized wrinkling patterns near defects on the stiff film/compliant substrate is neglected. In this paper, we show two morphological transitions of the local wrinkles induced by defects on an Au film/PDMS substrate. The observation shows that the straight wrinkles form perpendicularly to the line defects and the radial wrinkles form near spot-like defects. We observe that the extended radial wrinkles tend to split and evolve into branching patterns, this limits the deviation of the local wrinkle wavelength from the equilibrium wrinkle wavelength and causes the wrinkle wavelength to be always maintained in a narrow interval. Because the herringbone patterns have the minimum energy state, the straight and radial wrinkles evolve into herringbone wrinkles spontaneously. The morphological characteristic and evolution mechanism of the local wrinkles are described in detail. The observation may provide some clues to the formation and evolution of some localized wrinkling patterns in nature and multilayer materials.