Structure and Electron Engineering for Nitrate Electrocatalysis to Ammonia: Identification and Modification of Active Sites in Spinel Oxides.

Cobalt spinel oxides, which consist of tetrahedral site (AO4) and octahedral site (BO6), are a potential group of transition metal oxides (TMO) for electrocatalytic nitrate reduction reactions to ammonia (NRA). Identifying the true active site in spinel oxides is crucial to designing advanced catalysts. This work reveals that the CoO6 site is the dominant site for NRA through the site substitution strategy. The suitable electronic configuration of Co at the octahedral site leads to a stronger interaction between the Co d-orbital and the O p-orbital in O-containing intermediates, resulting in a high-efficiency nitrate-to-ammonia reduction. Furthermore, the substitution of metallic elements at the AO4 site can affect the charge density at the BO6 site via the structure of A-O-B. Thereafter, Ni and Cu are introduced to replace the tetrahedral site in spinel oxides and optimize the electronic structure of CoO6. As a result, NiCo2O4 exhibits the best activity for NRA with an outstanding yield of NH3 (15.49 mg cm-2 h-1) and FE (99.89%). This study introduces a novel paradigm for identifying the active site and proposes an approach for constructing high-efficiency electrocatalysts for NRA.

Visible-light-induced C(sp3)-H bromination of 4-methylthiophene derivatives with HBr/H2O2.

A convenient method to synthesize ethyl 4-(bromomethyl)thiophene-3-carboxylate derivatives has been developed via a visible-light-induced radical process in good yields and with wide functional group tolerance under air conditions and at ambient temperature. The present protocol has the advantages of a high atom economy, easy purification, and environmental friendliness as it employs HBr as the bromine source and the cheap and low-toxic H2O2 as the oxidant. The synthetic utility of this method is demonstrated by a gram scale reaction and its application in the innovative synthesis of the clinical drug relugolix.

Development of Line-Detected UV-Vis Absorption Microscope and Its Application to Quantitative Evaluation of Lithium Surface Reactivity.

Electrochemical reactions in practical batteries occur in confined environments where anode and cathode electrodes are separated only by a thin separator. Therefore, their electrochemical behaviors may differ from those obtained in the conventional experimental cells, where the two electrodes (working and counter electrodes) are largely separated compared to the batteries. The spatial and temporal distributions of the chemical species in the vicinity of each electrode are highly expected to be determined for quantitatively understanding the phenomena in confined environments. In the present study, we developed a line-detected UV-vis absorption microscope that simultaneously measures space-resolved UV-vis absorption spectra. This novel technique has been successfully applied to evaluate the reactivities of the highly reactive lithium (Li) surfaces in organic electrolyte solutions under in situ conditions. The quantitative evaluations of the dissolution rate of Li and the diffusion constant of the product were successfully realized by analyzing the space- and time-resolved absorption spectra based on Fick's law of diffusion. The microscopic technique is expected to open the door to understanding the fundamental electrochemistry in batteries.

Self-Cleaning Recyclable Multiplexed Photoelectrochemical Sensing Strategy Based on Exonuclease III-Assisted Signal Discrimination.

For discriminating the signals of multi-targets, multiplexed photoelectrochemical (PEC) detection is generally accomplished by modulating the light source or voltage, which prospect is usually limited by expensive instrumentation, tedious operational steps, and time-consuming material screening. To realize multiplexed determination on single photoelectric interface using the routine technique, a non-instrument-assisted strategy for signal discrimination needs to be explored. Herein, we propose an exonuclease III-mediated multiple PEC signals resolution strategy and construct a self-cleaning recyclable multiplexed PEC sensor using a porphyrin-bipyridine-based covalent organic framework (Por-Bpy COF) photocathode. Specifically, following the dual-target recognition event, exonuclease III cleaves the DNA strand attached to the magnetic bead so that the two signal labels can be separated. Once the signal label binds to the DNA on the electrode surface (E-DNA), exonuclease III turns to excise the DNA strand of the signal label and consequently the E-DNA can repeatedly bind different signal labels. As a result, distinguishable photocurrent signals of different targets can be generated on a single photoelectric interface. The feasibility of this multiplexed sensor is verified by detecting two coexisting mycotoxins aflatoxin B1 and zearalenone. On account of eliminating the instrumentation constraints and simplifying the experimental procedures, the proposed sensing strategy may provide a brand-new idea for the exploration of portable multiplexed PEC sensing devices.

Switchable Multiplex Photoelectrochemical Immunoassay of Aß42 and Aß40 Based on a pH-Responsive i-Motif Probe and Pyrene-Based MOF Photocathode.

In accurately diagnosing Alzheimer's disease (AD) and distinguishing AD from other dementia, the concentration ratio of amyloid-beta 42 (Aß42) to Aß40 is more reliable than the concentration of Aß42 alone. For the multiplex PEC assay, generating an independent photocurrent of multiple targets on a single interface is a great challenge. Herein, an i-motif-based switchable sensing approach is proposed to construct a pH-regulated multiplex PEC immunosensor for Aß42 and Aß40 by using Bi-TBAPy as an efficient photoactive cathode material. An independent photocurrent signal of Aß42 and Aß40 is produced through the regulation of the electron-transfer tunneling distance by a pH-dependent configuration transition of the i-motif DNA. In a 96-well plate, immunological recognition of Aß42 (or Aß40) coupled with an enzymatic catalytic reaction produces an acidic (or alkaline) lysis solution, which triggers the formation and unravelment of the i-motif structure. The above configuration transition regulates the distance between Au NPs labeled SH-DNA and Bi-TBAPy, leading to PEC signal switching. Smart integration of the pH-responsive switchable DNA probe with a high-efficiency photocathode enables the precise monitoring of Aß42 and Aß40 at a single interface in a wide detection range (10 fg/mL ∼ 1 µg/mL and 1 pg/mL ∼ 1 µg/mL) with detection limit of 4.5 fg/mL and 0.52 pg/mL, respectively. The proposed i-motif-based switchable sensing strategy paves a new avenue for a multiplex PEC assay on a single interface, showing great prospects in bioanalysis and early disease diagnosis.

Defect-rich Fe-doped NiS/MoS2 heterostructured ultrathin nanosheets for efficient overall water splitting.

With the demand for efficient hydrogen/oxygen evolution reaction (HER/OER) bifunctional electrocatalysts, defect-rich two-dimensional (2D) heterostructured materials attract increasing attention due to abundant active sites and facile mass/charge transfer. However, precise manipulation of lattice defects in a 2D heterostructured material is still a challenge. Herein, through pyrolytic sulfurization of a layered Fe-doped Ni/Mo MOF precursor, a series of defect-rich Fe-doped NiS/MoS2 ultrathin nanosheets were obtained. For 0.1Fe-NiS/MoS2, abundant lattice defects induced by Fe atoms provide more water adsorption sites, and intimate interface between NiS and MoS2 can optimize the adsorption energy of a HER/OER intermediate. As a result, both HER and OER activities are significantly enhanced. The respective overpotential is 120 mV and 297 mV for the HER and OER. Small Tafel slopes of 69.0 mV dec-1 and 54.7 mV dec-1 indicate favorable electrochemical reaction kinetics. The catalytic performance of this material can be compared with those of 20% Pt/C and RuO2 catalysts and top-rated MoS2-based materials. For overall water splitting, only 1.66 V voltage is required to deliver 10 mA cm-2. Long-term stability of 0.1Fe-NiS/MoS2 presents a prospect for its practical application.

A Vision Aided Initial Alignment Method of Strapdown Inertial Navigation Systems in Polar Regions.

The failure of the traditional initial alignment algorithm for the strapdown inertial navigation system (SINS) in high latitude is a significant challenge due to the rapid convergence of polar longitude. This paper presents a novel vision aided initial alignment method for the SINS of autonomous underwater vehicles (AUV) in polar regions. In this paper, we redesign the initial alignment model by combining inertial navigation mechanization equations in a transverse coordinate system (TCS) and visual measurement information obtained from a camera fixed on the vehicle. The observability of the proposed method is analyzed under different swing models, while the extended Kalman filter is chosen as an information fusion algorithm. Simulation results show that: the proposed method can improve the accuracy of the initial alignment for SINS in polar regions, and the deviation angle has a similar estimation accuracy in the case of uniaxial, biaxial, and triaxial swing modes, which is consistent with the results of the observable analysis.

Liposomal Controlled Release Ag-Activated DNAzyme Cycle Amplification on a 2D Pyrene COF-Based Photocathode for α-Synuclein Immunosensing.

Ultrasensitive and accurate monitoring of ultralow-level biomarkers is imperiously needed in clinical diagnosis. So far, exploring high-performance photocathodes and developing new sensing strategies have remained central challenges in photoelectrochemical bioassays. Herein, a two-dimensional (2D) pyrene covalent organic framework (COF, PAF-130) is exemplified for the first time as a high-performance photocathode for precise immunosensing of α-synuclein (α-Syn) by integrating a DNAzyme-induced signal cycle amplification strategy with Ag nanoparticles (NPs)-mediated liposomal immunoassay. Through sequential immunobinding, lysis treatment, and acidolysis, numerous Ag+ ions are released, and then they activate the DNAzyme, which further recycles the cleavage of hairpin DNA (HDNA) on the photoelectrode and induces signal cycle amplification. As a result, an ultralow detection limit (3.6 fg/mL) and a wide linear range (10-5-103 ng/mL) are achieved, which surpass those of most methods reported so far. The proposed sensing approach can be readily extended to detect various biomarkers by substituting the biorecognition events, providing great promise for biomedical and related applications.

"Dual Signal-On" Split-Type Aptasensor for TNF-α: Integrating MQDs/ZIF-8@ZnO NR Arrays with MB-Liposome-Mediated Signal Amplification.

Ultrasensitive and accurate detection of biomarkers in serum is of great importance for disease diagnosis and treatment. So far, the commonly used single-mode signal suffers from certain instinct drawbacks that restrict assay performances. Herein, we report the proof-of-concept fabrication of a split-type photoelectrochemical (PEC) and electrochemical (EC) dual-modal aptasensor for ultrasensitively tracing tumor necrosis factor-α, a noteworthy biological biomarker with essential clinical importance. By smart integrating molybdenum disulfide QDs/zeolitic imidazolate framework-8@ZnO nanorod arrays with a methylene blue-liposome-mediated signal amplification strategy, "dual signal-on" detection is accomplished based on a sandwich reaction of the target with aptamer-anchored carboxyl magnetic beads and an aptamer-confined MB liposome. Linear ranges of 5 fg/mL-5 µg/mL (detection limit 1.46 fg/mL) for PEC and 10 fg/mL-0.5 µg/mL (detection limit 6.14 fg/mL) for EC are obtained, respectively. An independent signal transduction mechanism supports the accuracy improvement, and a separate biological process from a translator enables convenient fabrication, short-time consumption, wider linearity, as well as outstanding reproducibility and stability in practical application. This work presents a universal bioassay route with prospects in biomedical and related areas.

CXXC finger protein 4 inhibits the CDK18-ERK1/2 axis to suppress the immune escape of gastric cancer cells with involvement of ELK1/MIR100HG pathway.

Gastric cancer, is the fourth most common tumour type yet, ranks second in terms of the prevalence of cancer-related deaths worldwide. CXXC finger protein 4 (CXXC4) has been considered as a novel cancer suppressive factor, including gastric cancer. This study attempted to investigate the possible function of CXXC4 in gastric cancer and the underlying mechanism. The binding of the ETS domain-containing protein-1 (ELK1) to the long non-coding RNA MIR100HG promoter region was identified. Then, their expression patterns in gastric cancer tissues and cells (SGC7901) were detected. A CCK-8 assay was used to detect SGC7901 cell proliferation. Subsequently, SGC7901 cells were co-cultured with CD3+ T cells, followed by measurement of CD3+ T cell proliferation, magnitude of IFN-γ+ T cell population and IFN-γ secretion. A nude mouse model was subsequently developed for in vivo validation of the in vitro results. Low CXXC4 expression was found in SGC7901 cells. Nuclear entry of ELK1 can be inhibited by suppression of the extent of ELK1 phosphorylation. Furthermore, ELK1 is able to bind the MIR100HG promoter. Overexpression of CXXC4 resulted in weakened binding of ELK1 to the MIR100HG promoter, leading to a reduced proliferative potential of SGC7901 cells, and an increase in IFN-γ secretion from CD3+ T cells. Moreover, in vivo experiments revealed that CXXC4 inhibited immune escape of gastric cancer cells through the ERK1/2 axis. Inhibition of the CXXC4/ELK1/MIR100HG pathway suppressed the immune escape of gastric cancer cells, highlighting a possible therapeutic target for the treatment of gastric cancer.

Epidemiological and genetic characteristics of porcine reproduction and respiratory syndrome virus 2 in mainland China, 2017-2018.

Porcine reproductive and respiratory syndrome virus 2 (PRRSV2) is a major threat to the global pig industry, particularly in China, the world's largest pig-rearing and pork-production country. Continuously monitoring the epidemiological and genetic characteristics of PRRSV epidemic strains is beneficial for prevention and control of infection. Previously, we reported the epidemiological and genetic characteristics of PRRSV2 in China from 2012 to 2016. Here, the epidemiological and genetic characteristics of PRRSV2 in China from 2017 to 2018 are reported. During these two years, we collected different types of porcine samples from 2428 pig farms in 27 provinces in China. Of the 7980 samples collected, 2080 (26.07%) were positive for PRRSV2 ORF5 by RT-PCR. The positive rate of PRRSV detection between different regions of China ranged from 8.12% to 29.33%, and from 7.96% to 55.50% between different months. Phylogenetic analysis based on the ORF5 gene revealed that the PRRSV2 strains currently circulating in China belong to five clades, and most of the PRRSVs detected are highly pathogenic PRRSVs (HP-PRRSVs; clade IV) and PRRSV NADC30-like strains (clade I). Sequence analysis revealed multiple amino acid mutation types, including amino acid changes and deletions in both the GP5 and Nsp2 proteins. The presence of these mutations may have an effect on the evolution of the virus by altering the viral titer and/or affecting the antibody response against the virus.

Overexpression of mircoRNA-137 inhibits cervical cancer cell invasion, migration and epithelial-mesenchymal transition by suppressing the TGF-ß/smad pathway via binding to GREM1.

BACKGROUND: Accumulating evidence has highlighted the tumor suppressive roles of microRNA (miRNAs) in cervical cancer (CC). In the present study, we aim to delineate the functional relevance of microRNA-137 (miR-137) in influencing epithelial-mesenchymal transition (EMT), and other CC cell biological activities via the TGF-ß/smad pathway by binding to GREM1. METHODS: Microarray analysis was initially adopted to predict the differentially expressed genes and the miRNAs related to CC, followed by the measurement of the expression patterns of GREM1, EMT-related factors in the CC tissues and the adjacent tissues. Dual luciferase reporter gene assay was conducted to determine the relationship between miR-137 and GREM1. Gain-of- and loss-of-function experiments were conducted to characterize the effects of miR-137 and GREM1 on the colony formation, proliferation, apoptosis, migration, and invasion of CC cells in vitro, and the tumorigenicity of the CC cells in nude mice. The TGF-ß/smad pathway was subsequently blocked with si-TGF-ß to investigate its involvement. RESULTS: Reduced miR-137 expression and increased GREM1 expression were predicted in CC, which was subsequently observed in the CC tissues and cells. Notably, GREM1 was a target gene of miR-137. The overexpressed miR-137 was found to inhibit EMT, cell proliferation, colony formation, invasion, migration and tumorigenesis in nude mice. In addition, miR-137 was noted to inhibit the activation of the TGF-ß/smad pathway by binding to GREM1. The silencing of TGF-ß1 was shown to reverse the effects induced by downregulated expression of miR-137. CONCLUSIONS: This study suggests that upregulated miR-137 suppresses the tumor progression in CC via blocking the TGF-ß/smad pathway by binding to and negatively regulating GREM1.

IL-8 is involved in radiation therapy resistance of esophageal squamous cell carcinoma via regulation of PCNA.

Esophageal squamous cell carcinoma (ESCC) is one of the prevalent and deadly cancers worldwide, especially in Eastern Asia. Our present study revealed that the expression of IL-8 was increased in radiation therapy resistance of ESCC cells. Targeted inhibition of IL-8 by its neutralization antibody (anti-IL-8) can re-sensitize ESCC cells to radiation therapy and suppress the expression of proliferating cell nuclear antigen (PCNA). IL-8 can regulate the expression of PCNA via modulating its mRNA stability and promoter activity. Mechanistically, IL-8 can regulate the expression of miR-27b-5p, which can directly bind with 3'UTR of PCNA to decrease its mRNA stability. Further, anti-IL-8 can decrease the expression of transcription factor YY1, which can bind with the promoter of PCNA to increase its transcription. Taken together, our data revealed that IL8 can regulate the radiation resistance of ESCC cells and expression of PCNA. It suggested that targeted inhibition of IL-8 may improve the clinical treatment efficiency of radio therapy.

A system composed of vanadium(IV) disulfide quantum dots and molybdenum(IV) disulfide nanosheets for use in an aptamer-based fluorometric tetracycline assay.

A system composed of vanadium(IV) disulfide quantum dots (VS2 QDs) and molybdenum(IV) disulfide (MoS2) nanosheets for use in an aptamer-based fluorometric tetracycline assay was developed. The tetracycline (TET) aptamer was first immobilzed on the VS2 QDs with a typical size of 3 nm. The blue fluorescence of the VS2 QDs (labeled with aptamer) with emission maxima at 448 nm (under excitation at 360 nm) was subsequently quenched by MoS2 nanosheets. If TET is recognized by the aptamer, the VS2 QDs drift away from the basal plane of the MoS2 nanosheets. This generated "turn-on" fluorescence of the VS2 QDs. A VS2 QD/MoS2 nanosheet-based fluorometric TET aptasensor was thus constructed. Selective and sensitive TET bioanalysis was realized in a linear range of 1 to 250 ng mL-1. The detection limit was 0.06 ng mL-1. Its applicability of determination of TET in milk samples has been demonstrated. Graphical abstractSchematic representation of the aptamer-based fluorometric tetracycline assay.

VS2 quantum dot label-free fluorescent probe for sensitive and selective detection of ALP.

As an essential enzyme highly associated with various human diseases, alkaline phosphatase (ALP) plays an important role in human tissues. Developing new materials and strategies for monitoring ALP is thus important. We have developed a novel label-free fluorescent sensing system for ALP activity that is based on the "turn-on" fluorescence of VS2 quantum dots. The fluorescence of VS2 quantum dots quenched by Fe3+ can be restored by ascorbic acid, which is generated by hydrolysis of L-ascorbic acid 2-phosphate catalyzed by ALP. Rapid, convenient, and sensitive detection of ALP is achieved in the range from 3 to 1000 U/L (R 2 =0.9985), with a detection limit of 0.27 U/L. The proposed sensor exhibits excellent selectivity for ALP compared with other enzymes and proteins, such as glucose oxidase, lysozyme, trypsin, human serum albumin, and bovine serum albumin. The reliability for ALP determination in human serum plasma has been demonstrated with satisfactory recovery, revealing promising application in clinical diagnosis and biomedical research. Graphical abstract Hydrothermally synthesized VS2 quantum dots serving as a novel turn-on fluorescent probe for detection of alkaline phosphatase (ALP) activity. AA L-ascorbic acid, AAP L-ascorbic acid 2-phosphate, NAC N-acetyl-L-cysteine.

A New Family of Photoluminescent Polymers with Dual Chromophores.

A new family of photoluminescent polymers with dual chromophores is prepared in this study by using poly(maleic anhydride-alt-vinyl acetate), acetone, and metal hydroxide. These polymers, which contain both bulky carboxylic ester groups and metal carboxylate groups, are found to be dual-emission photoluminescent, with a blue luminescence excitation-dependent group and a red luminescence excitation-independent group. These photoluminescence polymers with a nonconjugated structure and dual chromophores also show characteristics of aggregation-induced emission (AIE). The luminous intensities of the AIE fibers prepared using the polymers are found to increase after stretching, in contrast to traditional photoluminescent fibers with the aggregation-caused quenching property. The study also finds that the stretched fibers can emit the three primary colors when irradiated by ultraviolet, blue, and green light.

Fast raypath separation based on low-rank matrix approximation in a shallow-water waveguide.

Subspace algorithms based on higher-order cumulants were developed to achieve high-resolution separation in non-Gaussian processes. However, singular value decomposition (SVD) of a huge matrix is an unavoidable step of these algorithms. The memory space and running time required by the decomposition are super-linear with respect to the size of the matrix, which is prohibitive in terms of practical applications. Thus, in this paper, a fast raypath separation algorithm based on low-rank matrix approximation is proposed in a shallow-water waveguide. The experimental results illustrate that the proposed algorithm dramatically reduces the consumption of time and space, with arbitrarily small error, compared to conventional higher-order cumulant-based algorithms.

Water-Soluble Polymers with Strong Photoluminescence through an Eco-Friendly and Low-Cost Route.

Photoluminescence (PL) of nonconjugated polymers brings a favorable opportunity for low-cost and nontoxic luminescent materials, while most of them still exhibit relatively weak emission. Strong PL from poly[(maleic anhydride)-alt-(vinyl acetate)] (PMV) from low-cost monomer has been found in organic solvents, yet the necessity of noxious solvents would hinder its practical applications. Herein, through a novel, eco-friendly, and one-step route, PMV-derived PL polymers can be fabricated with the highest quantum yield of 87% among water-soluble nonconjugated PL polymers ever reported. These PMV-derived polymers emit strong blue emission in both solutions and solids, and can be transformed into red-emission agents easily. These PL polymers exhibit application potentials in light-conversion agricultural films. It is assumed that this work not only puts forward a convenient preparation routine for nonconjugated polymers with high PL, but also provides an industrial application possibility for them.

Nitrogen-rich graphene from small molecules as high performance anode material.

Nitrogen-rich graphene sheets were successfully achieved via facile thermal condensation of glucose and dicyandiamide at different temperatures during which dicyandiamide acts both as nitrogen source and sacrifice template. Devoid of surfactants or poisonous organic solvents, this small-molecule synthetic approach is a simple and cost-effective way to obtain nitrogen-rich graphene sheets (NRGS) with high specific surface area and large pore volume. Shown to be a promising anode material, the NRGS displayed high reversible capacity, excellent rate capability, and superior cycle performance. The superior lithium-storage performance is ascribed to the unique features of NRGS, including a large quantity of defects due to the high nitrogen doping level, favorable lithium ion transportation channels by virtue of the large surface area, and ultrahigh pore volume, as well as the crumpled two-dimensional structure.

Band Alignment Modulated Polarity-Switchable PEC Ratiometric Sensor through Coupling a pH-Responsive CuTCPP MOF with i-Motif Sensing tool.

In conventional ratiometric photoelectrochemical (PEC) sensors, the detection and reference signals are output sequentially from two independent photosensitive materials. In such a "two-to-two" ratiometric mode, unavoidable difference during dual-interface modification exists, resulting in questionable ratiometric signals and detection results. To address this issue, we propose a novel "one-to-two" ratiometric PEC sensor on a single electrode interface through pH-modulated band alignment engineering. The double ratiometric signals are generated by the synergistic action of a pH-responsive CuTCPP/WS2 photoelectric substrate material and the i-motif sensing tool. Specifically, a ternary heterostructure to generate a photoanodic detection signal is formed under alkaline conditions between CuTCPP/WS2 and signal label CdS QDs binding to the i-motif. While under acidic conditions, a photocurrent polarity conversion and signaling labels detachment, induced by the band realignment of CuTCPP/WS2 and the i-motif conformational switching, produce a reliable internal reference photocathodic signal. The feasibility of this two-wing signal generation strategy is validated by detecting mycotoxin ochratoxin A, which achieves accurate and reliable ratio detection results. Overall, this work provides guidance for the design of a PEC ratiometric determination system and exhibits great potential to be applied in practical analysis research.