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High energy consumption in pyrolyzing precursors for catalyst preparation would limit the application of nitrogen-doped carbon-based single-atom catalysts in actual pollutant remediation. Herein, we report an Fe single atom (7.67 wt %) loaded polyaniline catalyst (Fe-PANI) prepared via a simple impregnation process without pyrolysis. Both experimental characterizations and density functional theory calculations demonstrated that isolated -N═ group sites can fasten Fe atoms through Fe-N coordination in PANI, leading to a high stability of Fe atoms in a heterogeneous Fenton reaction. Highly dispersive yet dense -N═ groups in PANI can be protonated to be adsorption sites, which largely reduce the migration distance between reactive radicals and organics. More significantly, frontier molecular orbitals and spin-density distributions reveal that electrons can transfer from reduction groups of PANI to an Fe(III) site to accelerate its reduction. As a result, a remarkably boosted degradation behavior of organics under near-neutral conditions (pH 6), with low H

To solve surface carrier recombination and sluggish water oxidation kinetics of hematite (α-Fe

High-resolution X-ray imaging diagnosis is a critical method for measuring Rayleigh-Taylor instability growth and hot spot interface morphology in inertial confinement fusion experiments. In this study, we develop a quasi-monochromatic elliptical Kirkpatrick–Baez microscope based on aberration theory, breaking the aberration limit of conventional Kirkpatrick–Baez microscopes. The microscope was characterized in the laboratory for spatial resolution performance and modulation transfer function before being implemented in cavity experiments at the SG-III prototype laser facility. The results demonstrate that the edge-based method achieves a spatial resolution of 20%.

The advantages of the Low Earth Orbit (LEO) satellite include low-latency communications, shorter positioning time, higher positioning accuracy, and lower launching, building, and maintenance costs. Thus, the introduction of LEO satellite constellation as a regional navigation augmentation system for the current navigation constellations is studied in this paper. To achieve the navigation performance requirement with the least system cost, a synthetic approach is presented to design and deploy a cost-efficient LEO navigation augmentation constellation over 108 key cities. To achieve lower construction costs, the constellation is designed to be deployed by constrained piggyback launches, which brings additional complexity to the constellation design. Two optimization models with discrete and continuous performance indices are established. They are solved by the genetic algorithm and differential evolution algorithm, and both Walker and Flower constellations are adopted. Results for 77 and 70 satellites are obtained. During the construction phase, a synthesis procedure containing five impulses is proposed by utilizing natural drift under J 2 perturbation. This work presents a method for designing the optimal LEO navigation constellation under a constraint deployment approach with the lowest construction cost and a strategy to deploy the constellation economically.

An Earth-grazing asteroid can be captured into a gravitational bound orbit around the Earth during its transitory atmospheric journey. Otherwise, it will either escape back to space or plunge to the Earth directly. With fragmentation taken into account, we subdivide the captured and direct impact modes, expanding the above three modes into five – escaping, captured impact with and without fragmentation, and direct impact with and without fragmentation. We then investigate the conditions of those various impact modes of shallow-angle impacts of small stony asteroids no larger than 100 m in diameter. Moreover, the atmospheric entry processes of captured stony asteroids are further studied. Results show that asteroids with larger diameters are easier to fragment for less deceleration due to the smaller area-to-mass ratio, narrowing the corridor for capture. A captured asteroid can enter the atmosphere many times, highlighting itself by a series of explosive phenomena due to the shock wave it produced during every passage. The number of revolutions before its final entry increases as the theoretical perigee altitude rises. The multi-entry phenomenon of captured impact reduces the velocity and mass of the impactor and raises the possibility of an intact landing of the object via atmospheric dissipation. The time and space intervals between each entry make it difficult to identify whether the scattered impacts come from one captured impact event or just a series of different fireballs. The long path before its final hit also increases the difficulty of predicting the exact airburst position or landing site.

Due to structural tunability, high surface area, abundant pore structures, and abundant active sites, covalent heptazine frameworks (CHFs) constructed from heptazine and other molecular blocks are especially prominent. Here, we proposed a reaction-dependent strategy for designing two dimensional CHFs including high-throughput precursors screening, structure generation, and performance evaluation. Assuming that oxamide-like precursors can undergo the same thermal polymerization reaction as producing C

Stainless steels typically feature high toughness and good corrosion resistance. However, pitting corrosion can easily occur on stainless steel and the passivation film tends to be vulnerable under pressure or in brine environments. Metal corrosion is a long-standing challenge for the steel industry, forging a path to net-zero. Herein, by successive growth of a series of quantum confined nanocrystals such as quantum dots and nanorods with gradient band energy level alignment, high-performance photoelectrochemical cathodic protection for steel is demonstrated with remarkable mechanical and electrochemical stability. Under simulated solar light illumination, effective photoinduced protection can be realized for 304 stainless steel which enables long-term corrosion resistance in a 3.5 wt% NaCl solution. Unique nanotree-like structures and the quaternary material combination can store excess charges and release them gradually, enabling time-delay protection for metals after light excitation. Various promising functionalities as unique photoelectrodes can be envisioned arising from the proposed 3D nanotree morphology.

The outbreak of 2019 novel coronavirus pneumonia (COVID-19) has had a profound impact on people's lives around the world, and the spread of COVID-19 between individuals were mainly caused by contact transmission of the social networks. In order to analyze the network transmission of COVID-19, we constructed a case contact network using available contact data of 136 early diagnosed cases in Tianjin. Based on the constructed case contact network, the structural characteristics of the network were first analyzed, and then the centrality of the nodes was analyzed to find the key nodes. In addition, since the constructed network may contain missing edges and false edges, link prediction algorithms were used to reconstruct the network. Finally, to understand the spread of COVID-19 in the network, an individual-based susceptible-latent-exposed-infected-recover (SLEIR) model is established and simulated in the network. The results showed that the disease peak scale caused by the node with the highest centrality is larger, and reducing the contact infection rate of the infected person during the incubation period has a greater impact on the peak disease scale.

Mercury decontamination from water requires highly effective and efficient methods for maintaining public health and environmental protection. Herein, based on the coordination theory between functional groups and metal ions, we proposed phenylic carboxyl group-based poly(pyrrole methane)s (PPDCBAs) as highly efficient mercury removal materials for environmental remediation applications. It was found that PPDCBAs can efficiently adsorb and remove mercury(II) from aqueous solutions by functionalizing the molecular structure with phenylic carboxyl groups. Among the as-prepared PPDCBAs, poly[pyrrole-2, 5-diyl (4-carboxybenzylidane)] (PPD4CBA) with the carboxyl group at the para position can not only adsorb mercury over 1400 mg⋅g

Arteriosclerosis obliterans of lower limbs is a common peripheral arterial disease in clinics. With the development of endovascular therapy, the commonly used clinical treatment methods include balloon stent endovascular therapy and plaque resection. However, these treatment methods are often accompanied by high restenosis rate. This study aims to find a new treatment method from the genetic level.

Constellation is required to be highly stable over several years for a space-based gravitational wave observatory. However, the stability of the constellation can be affected by orbit insertion errors. The effects of orbit insertion errors on the constellation are mainly studied in this paper. Firstly, Monte-Carlo, Unscented Transformation Covariance Analysis Method (UTCAM) and Spherical Simplex Unscented Transformation Covariance Analysis Method (SSUTCAM) are used for simulation. The results indicate that UTCAM and SSUTCAM are highly efficient in calculating, with a relative error of less than 6%. Therefore, it is concluded that because of their accuracy and high efficiency, UTCAM and SSUTCAM can be adequately used in orbit insertion error analysis for a space-based gravitational wave observatory. Secondly, SSUTCAM is used to study the effects of position and velocity errors on the constellation. For the case in this paper, when the position error does not exceed 300 km, and the velocity error does not exceed 4 cm/s, the constellation remains stable.

Electrochemical water splitting is a promising method for the renewable production of high-purity hydrogen via the hydrogen evolution reaction (HER). Ni-Fe layered double hydroxides (Ni-Fe LDHs) are highly efficient materials for mediating the oxygen evolution reaction (OER), a half-reaction for water splitting at the anode, but LDHs typically display poor HER performance. Here, we report the preparation of self-organized Ag@NiFe layered double hydroxide core-shell electrodes on Ni foam (Ag@NiFe/NF) prepared by galvanic etching for mediating both the HER and OER (bifunctional water-splitting electrocatalysis). This synthetic strategy allowed for the preparation of organized hierarchical architectures which displayed improved the electrochemical performance by tuning the electronic structure of the catalyst and increasing the surface area utilization. X-ray photoelectron spectroscopy (XPS) and theoretical calculations revealed that electron transfer from the Ni-Fe LDH to Ag influenced the adsorption of the reaction intermediates leading to enhanced catalytic activity. The Ag@NiFe/NF electrode displayed overpotentials as low as 180 and 80 mV for oxygen and hydrogen evolution, respectively, at a current density of 10 mA cm-2, and improvements in the specific activity by ∼5× and ∼1.5× for the oxygen and hydrogen evolution reaction, respectively, compared to benchmark NiFe hydroxide materials. Additionally, an integrated water-splitting electrolyzer electrode can be driven by an AA battery.

In recent years, deep learning based bearing fault diagnosis is developing rapidly due to the increasing amount of industrial data. However, two major issues limit the application for deep learning: a) labeled data is difficult to obtain, and a lot of unlabeled data is more common in actual industrial production; b) the distribution of training and testing dataset will be different under different production environments or operations, which makes it difficult to generalize the trained model to another working condition. To solve these issues, we propose a domain adaptation convolutional neural network to diagnostic fault using Central Moment Discrepancy (CMD). In the proposed method, a convolutional neural network is applied to extract features from two differently distributed raw vibration signals, and the distribution discrepancy is reduced using CMD criterion. The proposed method can extract features with similar distribution from two different domains and make fault diagnosis for unlabeled data. The proposed method is proved to be effective in using CWRU dataset and Paderborn dataset under different working conditions.

The abundance of dolomitic strata in the geological record contrasts with the general rarity of locations where dolomite forms today, a discrepancy that has long posed a problem for their interpretation. Recent culture experiments show that dolomite can precipitate at room temperature, raising the possibility that many ancient dolomites may be of syngenetic origin. We compiled a large geodata set of secular variations in dolomite abundance in the Phanerozoic, coupled with compilations of genus richness of marine benthic invertebrates and sulfur-isotope variations in marine carbonates. These data show that dolomite abundance is negatively correlated to genus diversity, with four dolomite peaks occurring during mass extinctions. Dolomite peaks also correspond to the rapid increase in sulfur-isotope composition (δ34S), an indicator of enhanced sulfate reduction, in anoxic oceans. These results confirm that variations in dolomite abundance during the Phanerozoic were closely linked with changes in marine benthic diversity, with both in turn related to oceanic redox conditions.

Electrocatalytic conversion of carbon dioxide (CO2 ) is promising for balancing carbon cycles while producing value-added feedstocks. Herein, ultrathin ZnIn2 S4 nanosheets with abundant Zn vacancies are demonstrated for electrochemically reducing CO2 to formate. Specifically, a partial current density of 245 mA cm-2 with a near-unity faradaic efficiency of 94 % for formate generation was achieved over the ultrathin ZnIn2 S4 nanosheets in a flow cell configuration. Experimental and theoretical results revealed that abundant Zn vacancies in the ultrathin ZnIn2 S4 nanosheets with a high electrochemically active surface area synergistically optimized the intermediate binding energy and contributed to the boosted selectivity and activity. This work may provide useful understandings in designing efficient catalysts for selective CO2 electroreduction.

CeSb2 is a homologue of rare-earth diantimonides. This work reports a systematic study of a series of high-quality single crystals of CeSb2 grown by a self-flux method, which is a heavy fermion Kondo metal with intricate magnetic transitions. We have grown four types of crystals with different initial material ratios in order to investigate the effect of growth conditions on the quality of the as-grown crystals. The phase purity, morphology and composition of the synthesized samples were studied with X-ray diffraction, scanning electron microscopy, electron-probe microanalysis, and Raman-scattering spectroscopy to evaluate their quality. It is found that an inappropriate raw material ratio will lead to the inhomogeneity and poor crystallinity of the as-grown crystal. In addition, the electrical transport properties of the as-grown crystals were measured, from which the residual resistivity ratios were extracted to further examine the homogeneity and crystalline quality. Furthermore, the magnetoresistance properties of CeSb2 were observed. Through a systematic study on CeSb2, the most suitable starting ratio for the growth of CeSb2 was obtained, which might serve as a guide for the growth of other light rare-earth diantimonides.

A molecular pre-catalyst complex, [CuII(indH)(OClO3)(NCCH3)](ClO4)·CH3CN (1·CH3CN) with the 3N pincer ligand 1,3-bis(2′-pyridyl)iminoisoindoline (indH) was immobilized on indium tin oxide (ITO) transparent conducting substrate to generate O2 electrocatalytically for over 20 hours at pH 10 in a carbonated buffer, reaching a turnover of 139 with no signs of CuOx/Cu(OH)2 formation at the surface. Further electrolysis experiments revealed that the catalyst was present in the aqueous phase, despite the poor initial solubility of the pre-catalyst (1). In order to identify the actual form responsible for this important catalytic reaction, the aquo complex [CuII(ind)(OClO3)(OH2)]·CH3OH (2·CH3OH) was structurally characterized. Spectroscopic investigations of a solid isolated from the buffer used in the electrolysis reaction and solution equilibrium studies using 2 indicated that the [CuII(ind)(OH)] form occurs at pH 10. Electron paramagnetic resonance (EPR) spectroscopy and DFT calculations confirmed a distorted {3N,O}eq coordination plane in solution, as found in 2. The buffer (i.e. bicarbonate/carbonate) may affect reactivity in two ways: as an external base facilitating the proton-coupled electron transfer steps; and/or displacing the inner-sphere solvent molecules from the favourable quasi-equatorial position, thus inhibiting the catalysis. Structural features of a tri-nuclear cluster [CuII3(ind)3(μ3-CO3)(CH3OH)(OClO3)] (3) isolated under basic conditions confirmed that beside acting as an external base, the inhibiting effect of carbonate anions may also play a role. In acetonitrile-water solutions, where both 1 and 2 exhibit reasonable solubility, experimental findings supported by DFT calculations suggest that it is the ind− ligand which is being oxidized while the cupric ion remains redox-inactive which is very unusual yet of great significance for the creation of a new generation of low-cost Cu-based water oxidation catalysts as well as potentially other 1st row transition metals.

Objective: Infarction is one of the most common postoperative complications after surgical revascularization for moyamoya disease (MMD). Increased conspicuity of deep medullary veins (DMVs) on susceptibility-weighted imaging (SWI), known as “brush sign,” could predict the severity of MMD. This study aimed to reveal the features of the “brush sign” in preoperative SWI and to verify its relationship to postoperative infarction. Methods: Consecutive patients with MMD who had undergone cerebral revascularization surgery were included. Routine preoperative SWI was performed. The “brush sign” was defined according to the number of the conspicuous DMVs > 5 detected on SWI. Postoperative infarctions were defined as the high-intensity signal on postoperative DWI images, with or without neurologic deficits. The modified Rankin scale (mRS) was applied to evaluate the prognosis of patients. Results: In the enrolled 100 hemispheres, 35 were presented with the “brush sign.” Patients with ischemic onset manifestation and previous infarction history tended to present with the “brush sign.” Multivariate analysis showed that the “brush sign” (OR 13.669; 95% CI, 1.747–106.967, p = 0.013) and decreased rCBF (OR 6.050; 95% CI, 1.052–34.799, p = 0.044) were independent risk factors of postoperative infarction. Besides, the “brush sign” showed a significant correlation with a higher mRS score at discharge (p = 0.047). Conclusion: The findings strongly suggest that the presence of the “brush sign” preoperatively can be a predictor of infarction after surgical revascularization for ischemic MMD. It may contribute to an improved surgical result through focused perioperative management based on appropriate surgical risk stratification.

Gels prepared with the solvent-triggering method are attractive for their easy and fast preparation; however, the role of solvents in this process remains unclear, which hinders the efficient and accurate control of desired gel properties. In this study, the role of solvents in the solvent-triggering gelation process is studied using 9-fluorenylmethoxycarbonyl (Fmoc)-protected diphenylalanine (Fmoc-FF) as the gelator. Density functional theory (DFT)-based calculations and corresponding wavefunction analyses are conducted to identify the H-bonding interaction sites between the molecules. The calculation results clearly annotate the activating role of DMF and the triggering role of H

Noncovalent interactions are ubiquitous, endowing high feasibility on assembly and disassembly of gel network structure. Loading anticancer drugs in low molecular weight gelator (LMWG)-based gel through a noncovalently co-assembly process shows advantages of high efficacy, thixotropy, and controllable release. Drug-loaded fluorenylmethyloxycarbonyl-phenylalanine (Fmoc-F)/DMSO/H

Mitochondrial quality control plays an important role in maintaining mitochondrial homeostasis and function. Disruption of mitochondrial quality control degrades brain function. We found that flunarizine (FNZ), a drug whose chronic use causes parkinsonism, led to a parkinsonism-like motor dysfunction in mice. FNZ induced mitochondrial dysfunction and decreased mitochondrial mass specifically in the brain. FNZ decreased mitochondrial content in both neurons and astrocytes, without affecting the number of nigral dopaminergic neurons. In human neural progenitor cells, FNZ also induced mitochondrial depletion. Mechanistically, independent of ATG5- or RAB9-mediated mitophagy, mitochondria were engulfed by lysosomes, followed by a vesicle-associated membrane protein 2– and syntaxin-4–dependent extracellular secretion. A genome-wide CRISPR knockout screen identified genes required for FNZ-induced mitochondrial elimination. These results reveal not only a previously unidentified lysosome-associated exocytosis process of mitochondrial quality control that may participate in the FNZ-induced parkinsonism but also a drug-based method for generating mitochondria-depleted mammal cells.

The safety problems of lithium ion batteries (LIBs) have been the main obstacles that hinder their broad applications in portable electronic devices, electric vehicles, and energy storage. Such pro...

This study aims to investigate the long-term outcomes of unruptured giant intracranial aneurysms (GIAs) with different treatment modalities and to analyze the factors affecting prognosis. We performed a retrospective medical record review of patients with unruptured GIAs treated at our institution from 2011 to 2018. Prognosis was compared to the best medical treatment without intervention (conservative treatment, CT) and surgical (ST) or endovascular (ET) treatment. Risk factors for mortality were investigated. A total of 276 patients were included in this study. Patients received CT in 16.3%, ST in 30.1%, and ET in 53.6% of cases. After an average 7-year follow-up, the rupture rate after CT was 22.2%, accounting for an annual rupture rate of 7.3%. The postoperative complication rate was 30.1% and 8.1% after ST and ET, respectively. The recurrence rate after ET was 10.1%, compared with ST which was 1.2%. The follow-up mortality in unruptured GIAs was 26.7% after CT, 7.2% after ST, and 5.4% after ET. Older age (50~59, HR 5.877; 60~69, HR 8.565), size ≥ 40 mm (HR 3.916), and posterior circulation location (HR 6.411) were associated with increased mortality. ET significantly decreased mortality (HR 0.191). Unruptured GIAs warrant treatment if feasible due to the high rupture rate and mortality of the natural history. Older age, posterior circulation location, and larger size are risk factors for poor prognosis. Both ST and ET showed a lower mortality rate than CT. ST showed less likely recurrence compared to ET, while ET had a lower complication rate than ST.

We present a well-designed, low-cost, and simple synthetic approach to realizing the hybrid composites of Ag nanoparticle-decorated bacterial nanocellulose (denoted as Ag-NPs@BNC) as a three-dimensional (3D) flexible surface-enhanced Raman scattering (SERS) substrate with ultrahigh SERS sensitivity, excellent signal reproducibility, and stability. The homogeneous Ag-NPs with high density were in situ grown on the networked BNC fibers by the controlled silver mirror reaction and volume shrinkage treatment, which created uniformly distributed SERS "hot spots" in the 3D networked hybrid substrate. Attributed to these unique 3D hot spots, the as-presented Ag-NPs@BNC substrates exhibited ultrahigh sensitivity and good spectral reproducibility. Moreover, the hydrophilic BNC exhibits good permeability and adsorption performances, which could capture the target molecules in the highly active hot spot areas to further improve the SERS sensitivity. As a result, not only dye molecules (rhodamine 6G) but also toxic organic pollutants such as 2-naphthalenethiol and thiram have been detected using the hybrid substrates as SERS substrates, with sensitivities of 1.6 × 10-8 and 3.8 × 10-9 M, respectively. The good linear response of the intensity and the logarithmic concentration revealed promising applications in the rapid and quantitative detection of toxic organic pollutants. Besides, this self-supported Ag-NPs@BNC substrate demonstrated good stability and flexibility for varied detection conditions. Therefore, the 3D networked, flexible, ultrasensitive, and stable Ag-NPs@BNC substrate shows potential as a versatile SERS substrate in the rapid identification of various organic molecules.

A novel strategy has been proposed to produce in situ Li2S at the interfacial layer between lithium anode and the solid electrolyte, by using an amorphous-sulfide–LiTFSI–poly(vinylidene difluoride)...

The transition metal ions are often used to enhance the photoluminescent effciency in many compounds, which are always received as scintillators, optical sensors and memories, laser media, optoelec...

Pesticide and veterinary drug residues in food and environment pose a threat to human health, and a rapid, super-sensitive, accurate and cost-effective analysis technique is therefore highly required to overcome the disadvantages of conventional techniques based on mass spectrometry. Recently, the surface-enhanced Raman spectroscopy (SERS) technique emerges as a potential promising analytical tool for rapid, sensitive and selective detections of environmental pollutants, mostly owing to its possible simplified sample pretreatment, gigantic detectable signal amplification and quick target analyte identification via finger-printing SERS spectra. So theoretically the SERS detection technology has inherent advantages over other competitors especially in complex environmental matrices. The progress in nanostructure SERS substrates and portable Raman appliances will promote this novel detection technology to play an important role in future rapid on-site assay. This paper reviews the advances in nanostructure-based SERS substrates, sensors and relevant portable integrated systems for environmental analysis, highlights the potential applications in the detections of synthetic chemicals such as pesticide and veterinary drug residues, and also discusses the challenges of SERS detection technique for actual environmental monitoring in the future.

Lithium–sulfur (Li–S) batteries have become one of the most promising candidates for next-generation batteries owing to their high specific capacity, low cost, and environment-friendliness. Many efforts have been made to mitigate the “shuttle effect” through physical adsorption and chemical bonding. MoS2 has been proposed as a cathode material to provide effective anchoring sites for lithium polysulfides (LiPSs), but is still limited by its layer structure. Herein, we designed novel MoS2 nanorods with inner caves based on our previous work, and performed synchronous encapsulation of sulfur during the synthesis process. The outer MoS2 tubular shells physically inhibit the outward diffusion of polysulfide species while the inner particles chemically anchor the polysulfides to prevent shuttling. As the cathode matrix in Li–S batteries, the electrochemical results deliver a high initial discharge capacity of 1213 mAh g−1 for sulfur at 0.1 C. After cycling at 1 C for 300 cycles, the cells exhibit a capacity decay of only 0.076% per cycle and high average coulombic efficiency over 95%. The tubular MoS2 structure is an innovative and appealing design, which could be regarded as a prospective substrate for the improved performance of Li–S batteries.

Developing safe and high-energy-density lithium metal batteries (LMBs) are considered as the focus of next-generation rechargeable batteries. However, the inevitable lithium reacting with the liqui...