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Objective To identify a diagnostic indicator of lumbar spondylolysis visible in plain X-ray films. Methods One hundred and seventy-two patients with low back pain who received X-ray and computerized tomography (CT) examinations were identified and studied. They were divided into three groups: the spondylosis without spondylolisthesis (SWS) group, comprising 67 patients with bilateral pars interarticularis defects at L5 and without spondylolisthesis, the isthmic spondylolisthesis (IS) group, comprising 74 patients with L5/S1 spondylolisthesis and bilateral L5 pars interarticularis defects, and the control group, comprising 31 patients with low back pain but without spondylolysis. The sagittal diameters of the vertebral arch (SDVAs) of L4 and L5 were measured in lateral X-ray image, and the differences in SDVA between L4 and L5 (DSL4-5) in each case were calculated and analyzed. Results There were no significant differences in demographic characteristics among the three groups. In the SWS and IS groups, the SDVA of L5 was significantly longer than the SDVA of L4 (p < 0.001), whereas no significant difference found in the control group (p > 0.05). DSL4-5, in which the SDVA of L4 was subtracted from the SDVA of L5, significantly differed among the three groups (p < 0.001), and the normal threshold was provisionally determined to be 1.55 mm. Conclusions In bilateral L5 spondylolysis, the SDVA of L5 is wider than the SDVA of L4, and this difference is greater in isthmic spondylolisthesis. This sign in lateral X-rays may provide a simple and convenient aid for the diagnosis of spondylolysis.

New triclinic oxide material Ta1−x−yTixCryO2.5−δ (x = 0.077, y = 0–0.053) was synthesized via an oxalate co-precipitation method and tested as a novel electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Structural, electrical, and thermal properties of tantalum-based electrolyte co-doping with Cr3+/Ti4+ content were studied. X-ray powder diffraction showed that the crystal structure changed from orthorhombic to triclinic due to co-doped, and its high-temperature triclinic (pseudo-tetragonal) phase of tantalum pentoxide (H-Ta2O5) structure was stabilized to room temperature by doping. The crystalline phase facilitates the generation of more oxygen vacancies, which increases the electrical conductivity. The appearance of oxygen vacancies in the crystal with triclinic structure was confirmed with Raman spectroscopy and X-ray photoelectron spectroscopy. Scanning electron microscopy results exhibited the grain size decreases gradually with doping. Impedance curves showed high total ionic conductivity (1.48 × 10–1 S/cm at 700 °C) and low activation energy (Ea = 0.857 eV) for Ta0.9Ti0.067Cr0.033O2.5−δ. Thermal expansion coefficients (3.09 × 10–6 K−1) for co-doped samples were much lower in comparison to other electrolytes. Based on the results reported in this work, Ta1−x−yTixCryO2.5−δ can be an excellent oxygen conductor and recommended as solid electrolytes for IT-SOFC applications.

Background Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) has recently been suggested to cause rapid liver hypertrophy among patients having inadequate future liver remnant (FLR). However, ALPPS is still considered as a controversial hepatocellular carcinoma (HCC) treatment, especially for those with cirrhosis. This is ascribed to the high mortality and morbidity. The present study aimed to evaluate the ALPPS safety and feasibility for HCC patients related to hepatitis B virus (HBV). Methods This was a retrospective observational study. Consecutive HCC cases undergoing ALPPS or RH at our hospital between September 2014 and June 2018 were included. The demographic and clinical data of patients were collected, and oncological results of ALPPS patients were compared with those receiving right hepatectomy (RH). Results A total of 14 ALPPS patients and 21 RH patients were consecutively collected between September 2014 and June 2018. All ALPPS patients received stage II operations, with 100% resection of R0. The median growth of FLR between operations was 48% (range, ‒0.06% to 100%) in 17 days (range, 9–30 days). 3 ALPPS patients (21.4%) suffered from severe complications (grade ≥IIIb) according to the Clavien-Dindo grade, including 1 with renal failure, and 2 with the FLR/SLV of

Along with the rapid growth of the size and complexity of Internet of Things (IoT), the security of terminal devices has increasingly become a focus. In order to ensure the security of terminals, the trusted network connect (TNC) could realize not only the user authentication but also the platform attestation during the network access process. However, the existing TNC infrastructure is based on a centralized architecture, which is not suitable for distributed services. To address this problem, we present a blockchain-based TNC protocol named BTNC to ensure the reliability of terminals in IoT. Due to the decentralization, trustlessness, trackability, and immutability features of blockchain, BTNC is able to verify the security of terminal devices in IoT networks. First, we come up with some threats, including unauthorized user, illegal platform and platform replacement attack, then correspondingly define the security goals of our scheme. Second, combining key exchange protocol based on blockchain and D–H PN protocol included in TNC specification, we propose a blockchain-based trusted network connection protocol, which realizes mutual user authentication, platform attestation and trust network access by cryptography among terminals in IoT. Third, we make a security analysis in the PCL mode and conclude that our protocol can resist the attacks above. Finally, the performance overheads caused by our scheme are evaluated and the experiments show that it is efficient and feasible for different kinds of terminals in IoT.

PurposeUser resistance to change has been identified as a significant cause of information system (IS) implementation failure. Previous studies have proposed antecedents of user resistance to change. However, whether project leadership (e.g. authoritarian leadership) can lead to user resistance to change remains unclear. By drawing on project leadership, affective event theory and contingency theory of leadership, the authors address this void by empirically examining whether authoritarian leadership can lead to user resistance to change through the mediation of negative emotion and whether the magnitude of this mediation depends on the power distance level.Design/methodology/approachThis study examines the authors’ research model that integrates authoritarian leadership, negative emotion, power distance and user resistance to change using data from a matched-pair survey of 278 users and their supervisors involved in IS project implementation in China.FindingsNegative emotion plays a mediating role in the relationship of authoritarian leadership and user resistance to change. In addition, power distance moderates the relationship between authoritarian leadership and negative emotion and the indirect effect of authoritarian leadership on user resistance to change in IS project implementation through negative emotion.Originality/valueThe authors’ research provides a comprehensive understanding of the antecedents of user resistance to change in IS project implementation and ultimately contributes to the IS project implementation literature and practice.

The strongly correlated La0.67Sr0.33MnO3 (LSMO) thin films were deposited on the BaTiO3 (BTO) substrates to study the influence of temperature-dependent phase transition of BTO on the magnetic and electric transport properties of the LSMO films. Because of the large lattice mismatch between the LSMO and BTO substrates, the ultrathin LSMO film exhibits semiconducting transport behavior rather than the normal metal-insulator transition behavior. A Mn2+-O2--Mn3+ dominated double exchange interaction, which leads to a semiconducting to metallic transition behavior, was formed by the joint effect of the ion-liquid gating and phase transition of the BTO substrates. Our work shows a special way to modulate the conduction mechanism, which opens up a new field for further study of the magnetoelectric coupling of the LSMO/BTO heterostructures.

Linear magnetoresistance is generally observed in polycrystalline zero-gap semimetals and polycrystalline Dirac semimetals with ultrahigh carrier mobility. We report the observation of positive and linear magnetoresistance in a single-crystalline semiconductor Bi2O2Se grown by chemical vapor deposition. Both Se-poor and Se-rich Bi2O2Se single-crystalline nanoplates display a linear magnetoresistance at high fields. The Se-poor Bi2O2Se exhibits a typical 2D conduction feature with a small effective mass of 0.032m0. The average transport Hall mobility, which is lower than 5500 cm2 V-1 s-1, is significantly reduced, compared with the ultrahigh quantum mobility as high as 16260 cm2 V-1 s-1. More interestingly, the pronounced Shubnikov-de Hass oscillations can be clearly observed from the very large and nearly linear magnetoresistance (>500% at 14 T and 2 K) in Se-poor Bi2O2Se. A close analysis of the results reveals that the large and linear magnetoresistance observed can be ascribed to the spatial mobility fluctuation, which is strongly supported by Fermi energy inhomogeneity in the nanoplate samples detected using an electrostatic force microscopy images and multiple frequencies in a Shubnikov-de Hass oscillation. On the contrary, the Se-rich Bi2O2Se exhibits a transport mobility (

The accurate magnetoresistance (MR) measurement of individual nanostructures is essential and important for either the enrichment of fundamental knowledge of the magnetotransport mechanism or the facilitation of desired design of magnetic nanostructures for various technological applications. Herein, we report a deep investigation on the magnetotransport mechanism of a single CoCu/Cu multilayered nanowire via direct MR measurement using our invented magnetotransport instrument in situ scanning electron microscope. Off-axis electron holography experiments united with micromagnetic simulation prove that the CoCu layers in CoCu/Cu multilayered nanowires form a single-domain structure, in which the alignment of magnetic moments is mainly determined by shape anisotropy. The MR of the single CoCu/Cu multilayered nanowire is measured to be only 1.14% when the varied external field is applied along the nanowire length axis, which matches with the theoretical prediction of the granular film model. Density functional theory calculations further disclose that spin-dependent scattering at the interface between magnetic and nonmagnetic layers is responsible for the intrinsic magnetotransport mechanism.

The authors gratefully acknowledge the support of the National Natural Science Foundation of China (Nos. 51722208 and 51972215) and the Key Technologies Research and Development Program of Sichuan Province (No. 2018JY0007). Dr. X. Lv and Dr. J. Zhang contributed equally to this work.

The promise of high-density and low-energy-consumption devices motivates the search for layered structures that stabilize chiral spin textures such as topologically protected skyrmions. At the same time, layered structures provide a new platform for the discovery of new physics and effects. Recently discovered long-range intrinsic magnetic orders in the two-dimensional van der Waals materials offer new opportunities. Here we demonstrate the Dzyaloshinskii-Moriya interaction and N\'eel-type skyrmions are induced at the WTe2/Fe3GeTe2 interface. Fe3GeTe2 is a ferromagnetic material with strong perpendicular magnetic anisotropy. We demonstrate that the strong spin orbit interaction in 1T'-WTe2 does induce a large interfacial Dzyaloshinskii-Moriya interaction at the interface with Fe3GeTe2 due to the inversion symmetry breaking to stabilize skyrmions. Transport measurements show the topological Hall effect in this heterostructure for temperatures below 100 K. Furthermore, Lorentz transmission electron microscopy is used to directly image N\'eel-type skyrmions along with aligned and stripe-like domain structure. This interfacial coupling induced Dzyaloshinskii-Moriya interaction is estimated to have a large energy of 1.0 mJ/m^2, which can stabilize the N\'eel-type skyrmions in this heterostructure. This work paves a path towards the skyrmionic devices based on van der Waals heterostructures., Comment: 32 pages, 4 figures in the main text

Vehicular networks have become a visible reality enabling information sharing between vehicles to enhance driving safety and provide value-added services to drivers and passengers. However, false information might be injected into the network because of defective sensors, malicious vehicles, and so on. Therefore, an efficient mechanism to guarantee the reliability of information used by vehicles is of great importance in vehicular networks. To solve this problem, this article proposes a context-awareness trust management model to evaluate the trustworthiness of messages received by vehicles to ensure bogus information will not influence the driving decision-making process. In the proposed scheme, the trust evaluation result of an evaluation request is determined by available related information and the evaluation strategy in the current situation, which is unaffected by the presence of conflicting evidence and the trust level of entities in the network. Moreover, we design a reinforcement learning model that allows vehicles to adjust the evaluation strategy so as to maintain an accurate evaluation result in different driving scenarios. Extensive experiments were conducted in different driving scenarios to verify the effectiveness of the proposed model. The results show that our model is adaptive to different driving scenarios with negligible time overhead, regardless of the proportion of malicious nodes in the network. Furthermore, compared with three types of state-of-the-art trust models in different scenarios, our scheme can achieve a higher evaluation precision rate with no more computational and communication overhead in nonrandom road conditions.

It is of great clinical significance to design wound dressing materials with combined excellent wound healing properties and superior capability to suppress hypertrophic scar formation. This study aimed to examine if and how the cationicity of chitosan would affect the hypertrophic scar-related outcomes, through preparing carboxymethyl chitosan hydrogels with different genipin concentrations (2.5%, 5%, 10% and 15%, respectively). An optimum window of chitosan cationicity (5% in our case) demonstrated potential to mitigate hypertrophic scar in wound healing by suppressing the expression of a-smooth muscle actin (a-SMA) and promoting secretion of type I matrix metalloproteinases (MMP-1). In vivo, the CMCS-5% hydrogel again showed smaller, thinner and smoother wound appearance. Moreover, the CMCS-5% sample with additional incorporation of 2% (V/V) Aloe vera gel exhibited further improved performance in scar inhibition. Overall, such findings might have important implications in chitosan-based wound dressing design for high-quality wound repair and effective scar inhibition.

Study design Retrospective analysis. Setting China Rehabilitation Research Center, Beijing, China. Objective To explore possible mechanisms underlying spinal cord injury (SCI) in children caused by hyperextension of the spine while dancing. Methods The clinical records of 88 children with SCI (mean age, 5.97 years; age range, 4–10 years) admitted to our hospital from January 1989 to October 2019 were retrospectively reviewed. Computed tomography and magnetic resonance imaging were performed on the day of injury. The time from injury to development of paralysis, as well as post-injury activities were surveyed, while abnormal patterns on images, the range of the involved vertebrae, and the extents of edema and atrophy were assessed. Results Among the 88 patients, 6 (6.8%) were unable to move immediately after SCI, while paralysis occurred in 42, 23, and 17 patients at 60 min after SCI, respectively. The neurological level of injury of 84 patients was between T4 and T12. On sagittal T2-weighted images (T2WIs), the longitudinal range of spinal cord edema was more than one vertebral body in 65 patients, while spinal cord atrophy below T8 was found in 40 patients. On axial T2WIs, although three patients had none, long T2 signals were found in the central gray matter of seven patients. Meanwhile, necrosis of the central area combined with the peripheral white matter was observed in 57 patients, while three patients had total involvement on a cross section. Conclusion Ischemia-related damage, rather than direct trauma to the spinal cord, may play an important role in SCI due to spinal hyperextension during dancing.

The vehicular ad hoc network (VANET) has been considered as one of the most prominent technologies for improving the efficiency and safety of modern transportation systems. However, VANET will present a unique range of challenges and opportunities for security. In particular, key management, as the footstone to build a practical security framework in VANET, becomes a research hotspot. In this paper, we investigate key management based on blockchain for VANET. We first propose an efficient decentralized key management mechanism for VANET with blockchain (DB-KMM) to automatically realize the registration, update and revocation of user's public key. At the same time, we present a lightweight mutual authentication and key agreement protocol based on the bivariate polynomial. Then, we analyze the security of DB-KMM in the universally composable framework and show that the mechanism can prevent the typical attacks including internal attacks, DoS attacks, public key tampering attacks and collusion attacks. Finally, we analyze the performance of the proposed scheme through experiments and simulation. Experiment results show that DB-KMM has better performance than the existing schemes in terms of communication, storage, computation overhead and latency.

Broadband electromagnetic microwave absorbing materials with low density are highly demanded and faced with a development challenge for the critical applications into military stealth technology and electromagnetic pollution protection. Tailoring micro-structures and compositions of carbon-based multifunctional materials is a promising strategy to satisfy the expectation. Herein, we have firstly introduced nonmagnetic Cu element to tune microstructure, chemical composition of agglomerated Cu–Ni bimetallic alloys nanoparticles in gumdrop-cake-like CuNi/C nanofibers for the usage of high-quality light microwave absorbing materials, which can integrate the advantages of carbon nanofibers and CuNi nano solid solution particles. The CuNi/C nanofiber calcined at 650 °C temperature remarkably achieves a −55.1 dB strong reflection loss at 13.4 GHz frequency and a 7.5 GHz broad bandwidth (RL ≤ −10.0 dB) at 3 mm matching thickness, exhibiting a superior microwave absorption performance. This work demonstrates that introducing nonmagnetic Cu element could provide an effective way to improve the electromagnetic performance of carbon-based composites through tuning their microstructure.

Most existing studies on public transit network (PTN) rely on either small-scale passenger flow data or small PTN, and only traditional network parameters are used to calculate the correlation coef...

Identification of homogeneous region boundaries in a fractured rock mass is the basis of statistics and modeling of discontinuities. In engineering practice, an objective division can be obtained by adopting the major influential factors as indicators and the optimal approach as a tool. For discontinuities in Beishan, a main candidate site for Chinese high-level radioactive waste (HLW) repository, pretreatment techniques (e.g., sampling window truncation, sampling bias correction and block-net variation correction) were used to deal with field data. Programming was then applied to realize homogeneous region division via several methods (e.g., the improved Miller’s method, Mahtab and Yegulalp’s method, and correlation coefficient method). This study preliminarily examined these methods’ distinguishing capability, applicability, and limitations. Results showed that the applicability of the correlation coefficient method as well as the Mahtab and Yegulalp’s method was weak; the improved Miller’s method appeared most satisfactory, especially with a large-area strategy (34 blocks). Finally, two statistical homogeneous regions were obtained by applying the optimal approach to the Jijicao block. Findings can offer guidance for subsequent research on discrete fracture network (DFN) modeling and seepage path simulation, which is important for the prediction and evaluation of radionuclide migration in rock masses.

Considering serious concrete diseases from tunnel lining structure, the pre-suspended nanomaterials combined with superfine admixtures (nano-SA) are used to improve mechanical properties and durability of concrete. Fly ash combined with ultrafine particle microspheres were selected as composite admixtures based on comprehensive performance and application research analysis on the mineral nanomaterial admixtures. Compressive strength and flexural strength for the mortar specimens at different ages were investigated by the single or composite incorporation of the silica fume and the other nanomaterials with the different physical properties. The nano-SA determined by experiment was applied to regulate strength and durability of the concrete. The Scanning Electron Microscopy (SEM) was used to analyze microstructure of concrete with different prescriptions under freeze–thaw cycles. The effects of the nano-SA acting on concrete compactness were studied. The pre-suspended nanomaterial combined with superfine admixture is used for the experimental shotcrete of tunnel. The experimental results indicate that the nano-SA not only improves the workability and compressive strength of the shotcrete but also significantly reduces the rebound rate of the shotcrete. The rebound amount of the shotcrete incorporated with the nano-SA is decreased approximately 30% than without the nano-SA. It proves the excellent performance of the nano-SA and obvious economic benefits.

Topological Hall effect is an abnormal Hall response arising from the scalar spin chirality of chiral magnetic textures. Up to now, such an effect is only observed in certain special materials, but rarely in traditional ferromagnets. In this work, we have implemented the molecular beam epitaxy technique to successfully embed black-phosphorus-like bismuth nanosheets with strong spin-orbit coupling into the bulk of chromium telluride Cr2Te3, as evidenced by atomically resolved energy dispersive X-ray spectroscopy mapping. Distinctive from pristine Cr2Te3, these Bi-embedded Cr2Te3 epitaxial films exhibit not only pronounced topological Hall effects, but also magnetoresistivity anomalies and differential magnetic susceptibility plateaus. All these experimental features point to the possible emergence of magnetic skyrmions in Bi-embedded Cr2Te3, which is further supported by our numerical simulations with all input parameters obtained from the first-principle calculations. Therefore, our work demonstrates a new efficient way to induce skyrmions in ferromagnets, as well as the topological Hall effect by embedding nanosheets with strong spin-orbit couplings.

In order to improve the quality of life, people are paying more attention to food safety and flavor quality. As a new type of organic fertilizer, organic nutrient solution (ONS) is easily absorbed ...

Meesmann epithelial corneal dystrophy (MECD) is a rare dominantly inherited disorder that is characterized by corneal epithelial microcysts and is associated with mutations in the keratin 3 (KRT3) and keratin 12 (KRT12) genes. In this study, we report a novel mutation in the KRT12 gene in a Vietnamese pedigree with MECD. Slit-lamp examination was performed on each of the 7 recruited members of a Vietnamese family to identify characteristic features of MECD. After informed consent was obtained from each individual, genomic DNA was isolated from saliva samples and screening of KRT3and KRT12 genes was performed by Sanger sequencing. The proband, a 31-year-old man, complained of a 1-year history of eye irritation and photophobia. Slit-lamp examination revealed intraepithelial microcysts involving only the corneal periphery in each eye with clear central corneas and no stromal or endothelial involvement. Three family members demonstrated similar intraepithelial microcysts, but with diffuse involvement, extended from limbus to limbus. Sanger sequencing of KRT3 (exon 7) and KRT12 (exons 1 and 6) in the proband revealed a novel heterozygous KRT12 variant (c.1273G>A [p.Glu425Lys]) that was present in the three affected family members but was absent in the three family members with clear corneas. This study is the first report of a Vietnamese family affected with MECD, associated with an atypical peripheral corneal epithelial phenotype in the proband and a novel mutation in KRT12.

Ferromagnetic shape-memory alloys can realize smart functional sensors and actuators due to their distinctive capabilities of field-induced strain, which have attracted extensive interests. However, their response and transformation kinetics under the stimulus of Joule heating are still lack, which limits their extensive application into electrical-related sensors. In this work, we firstly report the dynamic structural transformation and magnetic domain evolution of smart shape memory alloy induced by Joule heating in-situ TEM with thermoelectric holder by using Ni2MnGa as experimental model. The stimulus of low-power Joule heating induces the reversible structural and magnetic domain transformations of the smart Ni2MnGa shape memory alloy. Whilst, high-power Joule heating induces an irreversible process of structural transformation and magnetic domain evolution. Our work should be significant to expand the smart shape memory alloy into electrical-related applications.

Meesmann epithelial corneal dystrophy (MECD) is a rare dominantly inherited disorder that is characterized by corneal epithelial microcysts and is associated with mutations in the keratin 3 (KRT3) and keratin 12 (KRT12) genes. In this study, we report a novel mutation in the KRT12 gene in a Vietnamese pedigree with MECD. Slit-lamp examination was performed on each of the 7 recruited members of a Vietnamese family to identify characteristic features of MECD. After informed consent was obtained from each individual, genomic DNA was isolated from saliva samples and screening of KRT3and KRT12 genes was performed by Sanger sequencing. The proband, a 31-year-old man, complained of a 1-year history of eye irritation and photophobia. Slit-lamp examination revealed intraepithelial microcysts involving only the corneal periphery in each eye with clear central corneas and no stromal or endothelial involvement. Three family members demonstrated similar intraepithelial microcysts, but with diffuse involvement, extended from limbus to limbus. Sanger sequencing of KRT3 (exon 7) and KRT12 (exons 1 and 6) in the proband revealed a novel heterozygous KRT12 variant (c.1273G>A [p.Glu425Lys]) that was present in the three affected family members but was absent in the three family members with clear corneas. This study is the first report of a Vietnamese family affected with MECD, associated with an atypical peripheral corneal epithelial phenotype in the proband and a novel mutation in KRT12.

Positioning based on visible light is gaining significant attention. But most existing studies rely on a key requirement: The object of interest needs to carry an optical receiver (camera or photodiode). We remove this requirement and investigate the possibility of achieving accurate positioning in a passive manner—that is, without requiring objects to carry any optical receiver. To achieve this goal, we propose PassiveVLP, in which we exploit the reflective surfaces of objects and the unique propagation properties of LED luminaires. We present geometric models, a testbed implementation, and empirical evaluations to showcase the opportunities and challenges posed by this new type of passive positioning. Overall, we show that our PassiveVLP can track with high accuracy (a few centimeters) a subset of an object’s trajectory, and it can also identify passively the object’s ID.

One of the universal problems in shield tunneling is face collapse caused by the sudden change of the soil in front of the tunnel face in weak sandy pebble stratum. In order to control the sudden change of the soil, the model test method is used to study the stability of the tunnel face in the sandy pebble stratum. The results indicate that (1) in sandy pebble stratum, the instability mode of the tunnel face can be divided into four stages of slow development stage, transition stage, rapid development stage and instability stage; (2) the influence of the ratio of the soil depth and the support pressure on the instability of the tunnel face can be divided into three stages of the insensitive stage, the sensitive stage and the failure stage; (3)finally, the instability failure shape of the sand–pebble stratum is upward developing in the lower part “chimney shape,” while the upperpart of the surface presents “spiral shape” subsidence and ultimately presents “crater shape”; (4) when excavation face is unstable, the surface horizontal settlement groove meets the normal distribution curve proposed by Peck and is similar to the settlement shape measured by the test. The study also found that the bamboo sticks with sand inserted in the soil in front of the tunnel face can increase the friction between the bamboo sticks and compact the soil, make the soil more prone to form soil arches, and effectively control the deformation of the soil in front of the tunnel face.

Partial substitution of chemical fertilizers by organic amendments is essential for improving the soil quality without yield loss. Fungi play an important role in soil quality because they decompose organic matter and cycle nutrients in the soil. However, there is limited information regarding the effect of different organic substitution rates (OSRs) on the soil quality and fungal community. This study investigated the relationship between the soil quality index and fungal community in a tea plantation under different OSRs of N, from a single application of synthetic fertilizer (NPK) to 100% N substitution with organic fertilizer (OM100). The OSRs were positively correlated with the soil physicochemical and biological soil quality index (SQI), but only the physicochemical SQI exhibited a significant relationship with tea production. The OSR also shifted the soil fungal community composition. Soil pH, soil organic C (SOC), microbial biomass C (MBC), and available potassium (AK) were the key characteristics that were significantly correlated with the variation of soil fungal community. Network analysis indicated that additional organic substitution can enhance the soil fungal network complexity, which also showed a positive correlation with the SQI. These results confirmed the feasibility of organic substitution for soil quality improvement, and implied that the soil fungal network complexity could be a new indicator for soil quality assessment.

Hybridizing hierarchical porous transition oxides composed of nanoscale building blocks is highly desirable for improving the electrochemical performance of energy storage. Herein, we contribute a fabrication of novel hierarchically nanoporous flower-shaped metal/transition oxide (Co/Co3O4–CoO) with controllable three-dimensional structure. The designed Co/Co3O4–CoO 3D flowers (3DFs) are made of petal-shaped nanoporous Co3O4–CoO nanosheets with tunable pore sizes, in which metallic Co nanoparticles tend to attach to the edge of larger ones. The hierarchically nanoporous 3DFs with bimodal pore size distribution and higher fraction of small nanopores exhibit a higher specific capacitance (902.3 F g−1 at current density of 2 A g−1) and better cyclability than the uniformly nanoporous 3DFs with unimodal pore size distribution and larger BET surface area. The enhanced capacitance is mainly derived from the synergistic effect of hierarchical nanopores, in which large nanopores disproportionately facilitate osmotic solution flux and diffusive solute transport, whilst small nanopores supply faster channels for electron transportation and ion diffusion. Our work should provide a strategy to fabricate a smart functional hierarchical nanoporous architecture with 3DF structures for the development of electrochemical energy storage materials.

In this paper, the synchronous control problem of photovoltaic grid-connected inverter with nonlinear impulse perturbation is studied. The mathematical model of photovoltaic grid-connected converter is established by using Kirchhoff's law. The nonlinear impulse perturbation characteristics of grid-connected current are studied and analyzed. Controllers are designed to suppress nonlinear impulse perturbation. The effectiveness of the controller is verified by Lyapunov stability theory. Finally, the simulation design is carried out by simulink in Matlab and the test platform is constructed. In this paper, simulation verification and data comparison are carried out by using various control methods for suppressing nonlinear impulse perturbation of grid-connected currents. Compared with PI controller, PR controller and other controller, the output harmonic content of photovoltaic inverter can be controlled within 1%, which can effectively reduce the harmonic content. The power quality of grid-connected current is improved. The feasibility and effectiveness of the control strategy proposed are verified by simulation and experiments.

Carbon nanomaterials have abundant sources but are difficult to use directly as a support for single atom catalysts (SACs) due to the lack of strong anchoring forces to restrict the movement and aggregation of metal atoms during the high-temperature heat treatment. Herein, we report a “self-catalysis” method for the synthesis of ferrous metal single-atom catalysts (SACs) FM–N–C (FM = Fe, Co, and Ni) with ∼2 wt% metal loadings on a carbon black support. The combination of experimental and theoretical evidence reveals a self-catalytic process from FM atoms to FM–N4 species, which involves (1) the adsorption of FM ions on the surface-oxidized carbon nanoparticles via oxygen coordination bonds (FM–O); (2) the catalytic decomposition of ammonia to nitrogen radicals on the FM atoms; (3) the replacement of coordinating oxygen with nitrogen. The precoordination of FM with oxygen is the key to the synthesis and reduces the energy barrier of ammonia decomposition and nitrogen bonding to the FM atoms. Thus, the formation of the FM–N4 species at a mild temperature of 600 °C is enabled. The as-synthesized FM–N–C SACs exhibit high catalytic activities towards O2 and/or CO2 reduction reactions. In contrast to the metal–organic framework-based SACs in which the MOF support significantly changes in size and weight, the self-catalysis technique is “minimally invasive” to the carbon support, thus benefiting the structural design of SACs by taking advantage of the abundant morphologies of the carbon nanomaterials.

Visualization of cation dynamics inside a living system represent a major breakthrough at the crossroad of chemistry and cellular physiology. Since the inception of BAPTA-based cellular calcium indicators in the 1980s, generations of chemical and genetically encoded ion indicators spanning the visible spectrum have been developed. In this article, we bring up three emerging concepts in this field: 1. red-shifting cation indicators towards far-red and near-infrared (NIR) channels; 2. directing the indicators to various subcellular localizations; 3. lowering the phototoxicity of indicators for long term recording. These initiatives collectively echo the advocate of 4D cellular physiology, where biological processes within living systems can be panoramically unveiled under 3D, long-term, and multi-channel imaging with unprecedented spatial and temporal resolution. This outlook poses exciting challenges and opportunities for chemists to upgrade the toolkit of fluorescent indicators as key enablers for a new era of imageomics.

Determining the exact occupation sites of the doping ions in spinel ferrites is vital for tailoring and improving their magnetic properties. In this study, the distribution and occupation sites of cations in MgFe

Enzymatic mineralization has become an effective approach to enhancing the stiffness of hydrogels for bone tissue engineering, but generally with limited toughness. On the other hand, double network cross-linking provides hydrogel with enhanced toughness. In this study, we integrated double cross-linking method with enzymatic mineralization to synthesize stiff and tough hydrogels. We have synthesized three kinds of sodium alginate-polyacrylamide (SA-PAM) double-network hydrogels and systematically compared the composition and structure differences, mechanical properties, and biological properties of the different hydrogels in the absence and presence of mineralization. In particular, we examined the role of specific cross-linking ions, i.e., calcium, zinc and strontium ions, in modulating the mineralization process. Synergistic effect of ionic cross-linking and enzymatic mineralization was clearly observed with dramatic increase in compressive modulus. In particular, mineralized hydrogel cross-linked with Srsup2+/supshowed the highest compressive Young's modulus of 17.28 ± 3.56 MPa, which was 37 times of that of the original hydrogel. In addition, it had the highest tensile Young's modulus at 2.60 ± 0.25 MPa and 84 ± 5.5% elongation at break. Such synergistic effect from Srsup2+/supwas attributed to a more uniformed mineralization process due to the early initiation of a more homogeneous nucleation process and subsequent denser mineralized structure. Cellular study also suggested that cell proliferation, adhesion and osteogenic differentiation were improved as a result of enzymatic mineralization. Our results provided an effective way for the preparation of stiff and tough hydrogels with osteogenesis, and demonstrated potential in bone tissue engineering applications. STATEMENT OF SIGNIFICANCE: Hydrogels with excellent stiffness, stability and biocompatibility have attracted significant attentions in the bone tissue engineering applications. Our results suggested that the synergistic effect of ionic cross-linking and enzymatic mineralization rendered more enhancement of the compressive and tensile stiffness of SA-PAM DN hydrogels, as well as the toughness, swelling stability and cellular response. In particular, mineralized hydrogel cross-linked with Srsup2+/supshowed the highest compressive Young's modulus of 17.28 ± 3.56MPa, which was 37 times of that of the original hydrogel. Such synergistic effect from Srsup2+/supwas attributed to a more uniformed mineralization process. The cell proliferation, adhesion and osteogenic differentiation were greatly improved as a result of enzymatic mineralization, where the MSCs cultured on strontium ion cross-linked mineralized hydrogel showed the best performance.

The rise of migrant workers has been a unique social phenomenon as China goes through industrialization, urbanization, and modernization. They are a special social group formed during the economic and social transition of the country. Migration of rural labor has pushed China on its new path toward industrialization and urbanization. Because of the urban-rural dual system of the country, however, it is difficult for migrant workers to be fully integrated into host cities, making them susceptible to negative emotions and mental health issues. Therefore, their mental health is an issue of great volume in the domains of social undertakings, people's livelihood, and public health. However, existing studies have paid limited attention to the psychological profile of migrant workers and even less to the interplays among their social capital, social integration, and mental health. Targeting China's internal migrant workers, this article tapped the interactions among their social integration, social capital, and mental health with a sample of the cross-sectional data from the China Labor Dynamics Survey (CLDS) in 2018. Multi-group structural equation modeling (SEM) was employed to test the moderating action of age by analyzing whether the mediation model differed significantly in the paths among young, middle-aged, and older migrant workers. The SEM based on bootstrapping suggested that, after controlling for the influence of gender, education, marital status, personal annual income, employer type, and self-rated health, migrant workers' social capital positively affect their mental health in a significant way, with social integration playing a mediating role. In terms of age difference, middle-aged migrant workers were more subject to the aforementioned mechanism than young ones, and young migrant workers were more affected by the mechanism than older ones. This study revealed different psycho-social interplays among social capital, social integration, and mental health across young, middle-aged, and elderly migrant workers. The findings could serve as an important theoretical reference and as practical guidance for improving policies concerning migrant workers' mental health and social benefits in the context of economic transition.

ObjectiveThe purpose of this study was to explore the effects of different methods of obtaining sperm for intracytoplasmic sperm injection (ICSI) cycles on the live birth rate (LBR) and neonatal outcomes.MethodsThis was a single-center retrospective cohort study conducted from January 2016 to December 2019. A total of 3557 ICSI cycles were included in the analysis, including 540 cycles in the surgically acquired sperm group and 3017 cycles in the ejaculated sperm group. The main outcome measure was the LBR.ResultsThe clinical pregnancy rate in the surgically acquired sperm group was 69.4%, which was significantly higher than the 59.7% clinical pregnancy rate in the ejaculated sperm group (P=0.01). The LBR of the surgically acquired sperm group was significantly higher than that of the ejaculated sperm group (63.1% vs. 51.2%, Pvs. 39.2%, P=0.04). Due to differences in the baseline characteristics of the two groups, multiple logistic regression analysis was performed. After multiple logistic regression analysis, the different methods of obtaining sperm were independent risk factors influencing the clinical pregnancy rate (adjusted odds ratio (AOR)=0.73, 95% confidence (CI)=0.56-0.95, P=0.02) and LBR (AOR=0.69, 95% CI=0.54-0.89, P=0.01). The preterm birth rate (AOR=1.42, 95% CI=0.62-3.25, P=0.41) and the incidence of low birth weight (AOR=1.03, 95% CI=0.45-2.34, P=0.95), small for gestational age (AOR=0.81, 95% CI=0.39-1.68, P=0.57), macrosomia (AOR=0.88, 95% CI=0.47-1.66, P=0.70) and large for gestational age (AOR=1.08, 95% CI=0.65-1.82, P=0.76) were not affected by the different methods.ConclusionThe clinical pregnancy rate and LBR of the surgically acquired sperm group were higher than those of the ejaculated sperm group. There was no significant difference between the neonatal outcomes of the two groups.

The development of membranes capable of precise solute-solute separation is still in its burgeoning stage without a standardized protocol for evaluating selectivity. Three types of membrane processes with different driving forces, including pressure-driven filtration, concentration difference-driven diffusion, and electric field-driven ion migration, have been applied in this study to characterize solute-solute selectivity of a commercial nanofiltration membrane. Our results demonstrated that selectivity values measured using different methods, or even different conditions with the same method, are generally not comparable. The cross-method incomparability is true for both apparent selectivity, defined as the ratio between concentration-normalized fluxes, and the more intrinsic selectivity, defined as the ratio between the permeabilities of solutes through the active separation layer. The difference in selectivity measured using different methods possibly stems from the fundamental differences in the driving force of ion transport, the effect of water transport, and the interaction between cations and anions. We further demonstrated the difference in selectivity measured using feed solutions containing single-salt species and that containing mixed salts. A consistent protocol with standardized testing conditions to facilitate fair performance comparison between studies is proposed.

We experimentally demonstrate C-band single-lane transmission of IM/DD 100-GBaud PS-PAM-16 signal at a record of 290.4-Gb/s net rate over 1-km SSMF using low-complexity nonlinear equalization and single DAC.

The usage of mobile phones has undergone tremendous growth in the past decades. Large amounts of mobile-phone signaling data (MSD) are generated while using various mobile phone applications. The large-scale MSD presents opportunities for transport planners to utilize it for better planning and management of the transportation system. In this paper, we use MSD to analyze subway passengers’ travel behavior and extract their complete travel trajectories. The complete travel trajectories of subway passengers include their trajectories, both inside and outside the subway system. In the first stage, the MSD from the subway base stations is selected, sorted by time, and the rough trajectory in the subway system is extracted. The ground base stations around the subway station are then considered to correct the boarding and alighting subway stations in order to obtain a more detailed trajectory. In the second stage, the service range of the base station is determined according to the Thiessen polygon, and a temporal dynamic threshold is proposed to extract the passenger’s stop point outside the subway system. Finally, the complete trajectories of subway passengers are obtained. The proposed algorithms are verified using a set of MSD collected in Suzhou, China. The results show that the proposed algorithms can effectively extract the complete travel trajectory of subway passengers.

Network security situation awareness (NSSA) is an integral part of cybersecurity defense, and it is essential for cybersecurity managers to respond to increasingly sophisticated cyber threats. Different from traditional security measures, NSSA can identify the behavior of various activities in the network and conduct intent understanding and impact assessment from a macro perspective so as to provide reasonable decision support, predicting the development trend of network security. It is a means to analyze the network security quantitatively. Although NSSA has received extensive attention and exploration, there is a lack of comprehensive reviews of the related technologies. This paper presents a state-of-the-art study on NSSA that can help bridge the current research status and future large-scale application. First, the paper provides a concise introduction to NSSA, highlighting its development process. Then, the paper focuses on the research progress of key technologies in recent years. We further discuss the classic use cases of NSSA. Finally, the survey details various challenges and potential research directions related to NSSA.

The practical cable design for optical submarine communications has a limited fiber pair count due to the mechanical considerations of cable weight and size. Consequently, multi-core fibers (MCFs) could exhibit higher capacity than the conventional single-mode fibers (SMFs) thanks to space division multiplexing (SDM). That is because the power supply to a submarine cable is fed by the voltage difference between shores. Under the power limited condition, SDM improves the cable capacity by using more paths which outperforms the SMF link whose capacity approximately complies with a logarithmic relationship to optical power. At the same time, fiber nonlinearity can be alleviated by the reduced power density of transmitted light in MCFs, due to the increased spatial diversity and mode coupling among coupled cores. In this work, we theoretically investigate the potentials of MCFs including weakly-coupled mutlicore fiber (WC-MCF) and strongly-coupled multicore fiber (SC-MCF) as the propagation media for submarine communications across the Atlantic and the Pacific. To fairly compare the performances of SMFs- and MCFs-based submarine cables, Gaussian noise (GN) model for SDM links is employed to optimize the systematic settings including modulation format, optical signal-to-noise ratio (OSNR) and single span length. Then, we develop an SDM and wavelength division multiplexing (WDM) fiber transmission model based on coupled nonlinear Schrodinger equations (CNSE) to investigate the optical filed coupling effect in MCFs-based cables. Developed transmission model has been self-examined by measuring the inter-core crosstalk (IC-XT) and spatial mode dispersion (SMD), referring to the set values. As indicated by the theoretical analysis, the WC-MCFs cable exhibits larger capacity than the SMFs cable, when fiber pair count is limited below 32. Moreover, the SC-MCFs cable outperforms the WC-MCFs cable thanks to the reduced fiber nonlinearity due to the random mode coupling and the assitance of multiple-input and multiple-output digital signal processing (MIMO-DSP). At last, the marginal influences of IC-XT, SMD and insertion loss of Fan-in and Fan-out couplers are also analyzed for the MCFs cable.