Efficient bifunctional electrocatalysts for hydrogen and oxygen evolution reactions are key to water electrolysis. Herein, we report a built‐in electric field (BEF) strategy to fabricate ...heterogeneous nickel phosphide‐cobalt nanowire arrays grown on carbon fiber paper (Ni2P‐CoCH/CFP) with large work function difference (ΔΦ) as bifunctional electrocatalysts for overall water splitting. Impressively, Ni2P‐CoCH/CFP exhibits a remarkable catalytic activity for hydrogen and oxygen evolution reactions to obtain 10 mA cm−2, respectively. Moreover, the assembled lab‐scale electrolyzer driven by an AAA battery delivers excellent stability after 50 h electrocatalysis with a 100 % faradic efficiency. Computational calculations combining with experiments reveal the interface‐induced electric field effect facilitates asymmetrical charge distributions, thereby regulating the adsorption/desorption of the intermediates during reactions. This work offers an avenue to rationally design high‐performance heterogeneous electrocatalysts.
By proposing and fabricating Ni2P‐CoCH heterostructure with large ΔΦ as a model catalyst for overall alkaline water electrolysis, the introduction of a strong built‐in electric field (BEF) is successfully realized to create the asymmetrical charge distributions on catalyst surfaces. The negative charge‐enriched Ni2P and positive charge‐enriched CoCH as active sites separately achieve high hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities.
In this paper, free vibration of a metal foam core sandwich (MFCS) beam embedded in Winkler–Pasternak elastic foundation is studied using the Chebyshev collocation method (CCM). This method can ...achieve high precision within the range allowed by the effective number of bits of computers. Three foam distribution types along the thickness direction are considered for the core. The Timoshenko beam theory is adopted and Hamilton’s principle is utilized to derive the boundary conditions and governing equations of the model. The numerical results show that natural frequencies of the sandwich beam initially increase and then decrease with the rise in thickness of metal foam core. By arranging the foam distribution in the core, natural frequencies of the sandwich beam can be significantly changed. Moreover, natural frequencies of the uniform foam distribution beam are insensitive to the foam coefficient. For the beam with non-uniform foam distribution, however, the natural frequencies increase or decrease with the foam coefficient, depending closely on the foam type. In addition, the present method is validated by comparing with the published ones for special cases.
The basic principle of quantum mechanics1 guarantees the unconditional security of quantum key distribution (QKD)2–6 at the cost of forbidding the amplification of a quantum state. As a result, and ...despite remarkable progress in worldwide metropolitan QKD networks7,8 over the past decades, a long-haul fibre QKD network without a trusted relay has not yet been achieved. Here, through the sending-or-not-sending protocol9, we achieve twin-field QKD10 and distribute secure keys without any trusted repeater over a 511 km long-haul fibre trunk that links two distant metropolitan areas. The fibre trunk contains 12 fibres in the cable, three of which are used for the quantum channel, optical synchronization and frequency locking, respectively. The remaining nine are used for classical fibre communication. Our secure key rate is around three orders of magnitude greater than that expected if the previous QKD field-test system was applied over the same length. Efficient quantum-state transmission and stable single-photon interference over such a long-haul deployed fibre pave the way to large-scale fibre quantum networks.A field test of twin-field quantum key distribution was implemented through a 511 km optical fibre. To this end, precise wavelength control of remote independent laser sources and fast time- and phase-compensation systems are developed.
A highly efficient, two-step, one-pot synthetic strategy for amides and peptides was developed by employing ynamides as novel coupling reagents under extremely mild reaction conditions. The ynamides ...not only are effective for simple amide and dipeptide synthesis but can also be used for peptide segment condensation. Importantly, no racemization was detected during the activation of chiral carboxylic acids. Excellent amidation selectivity toward amino groups in the presence of −OH, −SH, −CONH2, ArNH2, and the NH of indole was observed, making the protection of these functional groups unnecessary in amide and peptide synthesis.
Efficient biosynthesis of microbial bioactive natural products (NPs) is beneficial for the survival of producers, while self‐protection is necessary to avoid self‐harm resulting from ...over‐accumulation of NPs. The underlying mechanisms for the effective but tolerable production of bioactive NPs are not well understood. Herein, in the biosynthesis of two fungal polyketide mycotoxins aurovertin E (1) and asteltoxin, we show that the cyclases in the gene clusters promote the release of the polyketide backbone, and reveal that a signal peptide is crucial for their subcellular localization and full activity. Meanwhile, the fungus adopts enzymatic acetylation as the major detoxification pathway of 1. If intermediates are over‐produced, the non‐enzymatic shunt pathways work as salvage pathways to avoid excessive accumulation of the toxic metabolites for self‐protection. These findings provided new insight into the interplay of efficient backbone release and multiple detoxification strategies for the production of fungal bioactive NPs.
The biosynthesis of aurovertins involves a coordinated strategy for the tolerable production of fungal mycotoxins. A cyclase promotes the release of the polyketide backbone, while enzymatic acetylation functions as the major detoxification pathway, and non‐enzymatic shunt pathways function as salvage routes to avoid excessive accumulation of the toxic metabolites.
The risk of colitis and colorectal cancer increases markedly throughout adult life, endangering the health and lives of elderly individuals. Previous studies have proposed that bacterial ...translocation and infection are the main risk factors for these diseases. Therefore, in the present study, we aimed to identify the underlying mechanism by focusing on the mucus barrier function and mucin‐type O‐glycosylation. We evaluated alterations in the colon mucus layer in 2‐, 16‐, and 24‐month‐old mice and aged humans. Aged colons showed defective intestinal mucosal barrier and changed mucus properties. The miR‐124‐3p expression level was significantly increased in the aged distal colonic mucosa, which was accompanied by an increase in pathogens and bacterial translocation. Meanwhile, T‐synthase, the rate‐limiting enzyme in O‐glycosylation, displayed an age‐related decline in protein expression. Further experiments indicated that miR‐124‐3p modulated O‐glycosylation by directly targeting T‐synthase. Moreover, young mice overexpressing miR‐124‐3p exhibited abnormal glycosylation, early‐onset, and more severe colitis. These data suggest that miR‐124‐3p predisposes to senile colitis by reducing T‐synthase, and the miR‐124‐3p/T‐synthase/O‐glycans axis plays an essential role in maintaining the physiochemical properties of colonic mucus and intestinal homeostasis.
Young colons show intact inner layer and mucin‐type O‐glycosylation, limiting microbiota access to the epithelium. Age‐related alteration in miR‐124‐3p/T‐synthase/O‐glycans axis and reduction in mucus thickness weakened the mucus barrier, leading to abnormal bacterial intrusion and increased susceptibility to senile colitis.
The piezoelectric effect of biological piezoelectric materials promotes bone growth. However, the material should be subjected to stress before it can produce an electric charge that promotes bone ...repair and reconstruction conducive to fracture healing. A novel method for in vitro experimentation of biological piezoelectric materials with physiological load is presented. A dynamic loading device that can simulate the force of human motion and provide periodic load to piezoelectric materials when co-cultured with cells was designed to obtain a realistic expression of piezoelectric effect on bone repair. Hydroxyapatite (HA)/barium titanate (BaTiO
) composite materials were fabricated by slip casting, and their piezoelectric properties were obtained by polarization. The d
of HA/BaTiO
piezoelectric ceramics after polarization was 1.3 pC/N to 6.8 pC/N with BaTiO
content ranging from 80% to 100%. The in vitro biological properties of piezoelectric bioceramics with and without cycle loading were investigated. When HA/BaTiO
piezoelectric bioceramics were affected by cycle loading, the piezoelectric effect of BaTiO
promoted the growth of osteoblasts and interaction with HA, which was better than the effect of HA alone. The best biocompatibility and bone-inducing activity were demonstrated by the 10%HA/90%BaTiO
piezoelectric ceramics.
Myocardial ischemia/reperfusion injury (IRI) induces cardiomyocytes death and leads to loss of cardiac function. Circular RNAs (circRNA) have gain increasing interests in modulating myocardial IRI. ...In this study, we aim to investigate the role and exact mechanism of circTLK1 in the pathogenesis of myocardial IRI.
Myocardial IRI was developed in mice with measuring hemodynamic parameters and the activity of serum myocardial enzymes to evaluate cardiac function. HE and TTC staining were performed to assess infarct area. Expression patterns of circTLK1 and miR-214 were investigated using qRT-PCR assay. Gene expression of circTLK1, miR-214 or RIPK was altered by transfecting with their overexpression or knockdown vectors. The apoptosis of cardimyocytes was assessed by TUNEL staining and Caspase-3 activity analysis. Apoptosis-related markers Bcl-2, Bax, and caspase3, as well as TNF-α signals were determined by western blotting. The interactions of circTLK1/miR-214 and miR-214/RIPK1 were verified using luciferase reporter assay. RNA immunoprecipitation (RIP) was subjected to further definite the direct binding of circTLK1/miR-214. The regulatory network of circTLK1/miR-214/RIPK1 was further validated in vivo.
circTLK1 was an up-regulated circRNA found in a myocardial IRI mouse model. Mice with silencing circTLK1 significantly alleviated the impaired cardiac function indexes and decreased infarct area, thus attenuating the pathogenesis of myocardial IRI. Knockdown of circTLK1 dramatically decreased cardiomyocytes apoptosis, which was determined by apoptosis-related proteins. miR-214 was identified as a downstream effector to reverse circTLK1-mediated damage effects in myocardial IRI. miR-214 could directly target RIPK1 via binding to its' 3′-UTR. Overexpression of RIPK1 led to impaired cardiac function indexes, increased infarct area, and cell apoptosis, which abolished the protective effects of miR-214. The TNF signaling pathway was demonstrated to be involved in the circTLK1/miR-214/RIPK1 regulatory network in myocardial IRI.
Taken together, our study revealed an up-regulated circRNA, circTLK1, could exacerbate myocardial IRI via targeting miR-214/RIPK1-mediated TNF signaling pathway, which may provide therapeutic targets for treatment.
Puerarin is an isoflavone isolated from the medicinal plant Pueraria lobata. The purpose of this study was to study the antiinflammatory and antimatrix‐degrading effects of puerarin in a rat ...osteoarthritis (OA) model and its protective effects on joints. The rat OA model was established by anterior cruciate ligament transection (ACLT) surgery. Rats (n = 40) were divided into nontreated OA, OA + celecoxib (2.86 mg/kg), OA + puerarin (50 and 100 mg/kg), and control groups. Two weeks after surgical induction, puerarin was administered by gavage daily for 8 weeks. After 8 weeks, macroscopic observation and histopathological images showed that cartilage damage was reduced after puerarin and celecoxib treatment, the intensity of Safranin O staining was high, and the OARSI scores were significantly reduced compared to the OA group. Puerarin reduced the expression of MMP‐3, MMP‐13, ADAMTS‐5, and COX‐2 in the cartilage tissue of ACLT rats, inhibited the production of IL‐1β, IL‐6, and TNF‐α inflammatory factors, increased Type II collagen content, and altered the expression of serum OA cartilage degradation/bone turnover biomarkers (CTX‐I, CTX‐II, COMP, and PIINP). Based on these findings, we speculate that puerarin supplement to attain recovery from OA damage.
Data based source localization in complex networks has a broad range of applications. Despite recent progress, locating multiple diffusion sources in time varying networks remains to be an ...outstanding problem. Bridging structural observability and sparse signal reconstruction theories, we develop a general framework to locate diffusion sources in time varying networks based solely on sparse data from a small set of messenger nodes. A general finding is that large degree nodes produce more valuable information than small degree nodes, a result that contrasts that for static networks. Choosing large degree nodes as the messengers, we find that sparse observations from a few such nodes are often sufficient for any number of diffusion sources to be located for a variety of model and empirical networks. Counterintuitively, sources in more rapidly varying networks can be identified more readily with fewer required messenger nodes.
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