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Risk monitoring and risk prediction are of great significance to improve the safety of urban rail operation. Existing studies often analyze the topological characteristics of accident networks from the perspective of network theory, in order to point out the role of specific influencing factors in urban rail accidents. This article proposes a risk analysis method of urban rail operation accidents, which takes risk factors, risk points and risk events as nodes to form a network, and combines the interaction between risk points to evaluate the safety of the whole system. The existing system safety analysis methods all build models based on the accidents that have occurred. Based on the analysis of the existing urban rail transit infrastructure and operating environment, this article puts forward the risk factors and risk points that may cause risk events, and combines the mechanical connection, electrical connection and signal connection among risk points to deeply explore the interaction between risks so as to find the key risk points that cause accidents and evaluate the safety of the whole system. The results show that the proposed risk analysis method can provide effective theoretical support for risk monitoring.

Excessive oxidative stress is the main cause of neurotransmitter metabolism disorder in the brain with depression. Lysosomal hypobromic acid (HOBr) is an important reactive oxygen species produced in oxidative stress. Its abnormal content can lead to macromolecular damage and neurodegenerative diseases. However, due to the high reactivity and low concentration of HOBr and the lack of in situ imaging methods, the role of HOBr in depression is not clear. Herein, based on the HOBr-initiated aromatic substitution of a tertiary amine, we developed a novel two-photon (TP) fluorescence probe (

Steel trusses are widely utilized in engineering structures, and their optimization is essential for enhancing structural performance and reducing material consumption. Existing optimization methods for steel trusses predominantly rely on the trial-and-error method, which is not only inefficient but also inaccurate. Therefore, this study focused on the optimization of steel trusses using an efficient and accurate optimization methodology. Based on a genetic algorithm and the finite element method, both mono- and multi-parameter optimization designs for steel trusses were executed, an applicable optimization design method for steel trusses was established, and corresponding optimization design programs were developed. The analysis demonstrates that the proposed optimization method effectively optimizes truss height and member cross-section, leading to a significant reduction in material consumption. Compared to the traditional trial-and-error method, the proposed optimization method exhibits adequate calculation accuracy and superior optimization efficiency, thereby providing a robust theoretical foundation for the engineering design of steel trusses.

Cancer, as a malignant tumor, seriously endangers human health. The study of cancer diagnosis and therapy has great practical significance. The development of theranostic agents has become a very important research topic. Nevertheless, some existing agents still have imperfections, such as complex structures and difficult syntheses. Therefore, it is urgent for researchers to develop simple novel theranostic agents. In this study, the precipitated fluorophore

Glutathione (GSH) is a key maintainer of cellular redox balance and plays an important role in many physiological effects. For example, GSH has been widely implicated in cancer initiation, progression and metastasis. Moreover, the concentrations of GSH in tumor cells can influence drug resistance. Given the serious harmfulness of cancer and the important roles of GSH in cancer, it has great significance to development probes for screening of tumor cells and real-time monitoring of GSH fluctuations in tumor cells. However, no targetable probe for reversible imaging of GSH in tumor cells has been reported. Herein, we constructed a melatonin-based targetable and reversible fluorescent probe (GR-MT) for screening of tumor cells and real-time imaging of GSH fluctuations in tumor cells. The probe uses coumarin as the skeleton, Michael addition reaction as the reaction mechanism, and melatonin as the targeted groups of tumor cells. The experimental results demonstrate this probe has many advantages including high selectivity, satisfactory sensitivity, excellent reversible ability, rapid reaction speed, and outstanding targetability of tumor cells. Therefore, this study provides a promising tool for tumor cells screening and real-time detection of GSH fluctuations in specific tumor cells.

A highly selective and sensitive water-soluble naphthalimide-based turn-on fluorescent probe was synthesized to detect Hg2+ in living cells and zebrafish.

Cancer is a serious threat to human health, and there is an urgent need to develop new treatment methods to overcome it. Organelle targeting therapy, as a highly effective and less toxic side effect treatment strategy, has great research significance and development prospects. Being an essential organelle, the Golgi apparatus plays a particularly major role in the growth of cancer cells. Acting as an indispensable and highly expressed antioxidant in cancer cells, glutathione (GSH) also contributes greatly during the Golgi oxidative stress. Therefore, it counts for much to track the changes of GSH concentration in Golgi for monitoring the occurrence and development of tumor cells, and exploring Golgi-targeted therapy is also extremely important for effective treatment of cancer. In this work, we designed and synthesized a simple Golgi-targeting fluorescent probe GT-GSH for accurately detecting GSH. The probe GT-GSH reacting with GSH decomposes toxic substances to Golgi, thereby killing cancer cells. At the same time, the ratiometric fluorescent probe can detect the concentration changes of GSH in Golgi stress with high sensitivity and selectivity in living cells. Therefore, such a GSH-responsive fluorescent probe with a Golgi-targeted therapy effect gives a new method for accurate treatment of cancer.

The particle-scale shear and tensile strength measurements of microbial-induced calcite precipitation (MICP) treatment have been investigated in this paper. Glass beads were used to represent sand particles. Three particle-scale test setups were developed to measure the tensile, shear, and cyclic shear strength of MICP-Treated CaCO3 bonds between glass beads. Sporosarcina pasteurii bacterial cells were introduced to precipitate CaCO3 and form cementation bonds between glass beads. The preliminary particle-scale test (Test setup 1) was designed to measure the shear and tensile strength of CaCO3 bonds precipitated between glass beads mounted on optical fiber sensors with known properties. Shear and tension loads were applied to the CaCO3 bonds by the displacement actuators controlling the movement of movable stages. The improved particle-scale test setup (Test setup 2) was developed using a larger and stable reaction chamber, an automated injecting system, and stiff bending elements (instead of optical fibers) that were connected to glass beads to improve measurements. Deflections of the bending elements were measured to calculate the tensile and shear strength of the CaCO3 bonds using the beam theory. The enhanced particle-scale test setup (Test setup 3) was developed to directly measure the shear and tensile forces generated in CaCO3 bonds using load cells and LVDTs to investigate the monotonic and cyclic response of the CaCO3 bonds. For the tests using Test setup 3, the shear and tensile strengths were 378 and 446 kPa, respectively. The work was made possible by an NPRP 819292766, a grant from the Qatar National Research Fund (a member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors. Scopus

Wastewater treatment plants (WWTPs) are an important source of microplastics (MPs) entering the aquatic environment. As environmental awareness increases, WWTPs are gradually using constructed wetlands (CWs) in the depth treatment stage. There were few studies related to MPs removal efficiency of CWs, especially in multi-stage and multi-combinations CWs. Therefore, we studied MPs characteristics and removal in a typical CWs WWTP in Changsha, comparing the MPs removal efficiencies of different processes in a WWTP, focusing on the MPs abundance variation in different stages CWs. Result showed that the MPs removal efficiency of Phase Ⅰ was 87.72% and that of Phase II was 80.65%. Approximate estimates showed that the daily discharge of MPs reached 7.20 * 10

A simple pyridine-based highly specific fluorescent probe was constructed to trace hypochlorous acid in lysosomes of living cells.

Mercury (Hg) is a heavy metal with high toxicity and easy migration; it can be enriched through the food chain, and cause serious threats to the natural environment and human health. So, the development of a method that can be used to detect mercury ions (Hg2+ ) in the environment, in cells, and in organisms is very important. Here, a new 7-hydroxycoumarin-derived carbonothioate-based probe (CC-Hg) was designed and synthesized for detection of Hg2+ . After addition of Hg2+ , a large fluorescence enhancement was observed due to the formation of 7-hydroxyl, which reinforced the intramolecular charge transfer process. The CC-Hg probe had good water solubility and selectivity. Moreover, the probe was able to detect Hg2+ quantitatively over the concentration range 0-2 μM and with a detection limit of 7.9 nM. Importantly, we successfully applied the probe to detect Hg2+ in water samples, in living cells, and in zebrafish. The experimental results demonstrated its potential value in practical applications.

Considering that mercury ions (Hg

The outbreak and spread of Corona Virus Disease 2019 (COVID-19) has led to a significant increase in the consumption of sodium hypochlorite (NaOCl) disinfectants. NaOCl hydrolyzes to produce hypochlorous acid (HOCl) to kill viruses, which is a relatively efficient chlorine-based disinfectant commonly used in public disinfection. While people enjoy the convenience of NaOCl disinfection, excessive and indiscriminate use of it will affect the water environment and threaten human health. Importantly, HOCl is an indispensable reactive oxygen species (ROS) in human body. Whether its concentration is normal or not is closely related to human health. Excessive production of HOCl in the body contributes to some inflammatory diseases and even cancer. Also, we noticed that the concentration of ROS in cancer cells is about 10 times higher than that in normal cells. Herein, we developed a HOCl-activatable biotinylated dual-function fluorescent probe BTH. For this probe, we introduced biotin on the naphthalimide fluorophore, which increased the water solubility and enabled the probe to aggregate in cancer cells by targeting specific receptor overexpressed on the surface of cancer cell membrane. After reacting to HOCl, the p-aminophenylether moiety of this probe was oxidatively removed and the fluorescence of the probe was recovered. As expected, in the PBS solution with pH of 7.4, BTH could give full play to the performance of detecting HOCl, and it has made achievements in detecting the concentration of HOCl in actual water samples. Besides that, BTH had effectively distinguished between cancer cells and normal cells through a dual-function discrimination strategy, which used biotin to enrich the probe in cancer cells and reacted with overexpressed HOCl in cancer cells. Importantly, this dual-function discrimination strategy could obtain the precision detection of cancer cells, thereby offering assistance for improving the accuracy of early cancer diagnosis.

Compared with the marine shale from North America, Chinese lacustrine basins have more complex geological and reservoir conditions, which makes the selection of sweet spot intervals in the shale oil reservoir particularly difficult. It is thus crucial to accurately predict the shale oil sweet spots for effective exploration and development of shale oil in a lacustrine basin. In this paper, we propose an innovative evaluation method of shale oil sweet spots, which considers five primary parameters (i.e., total oil content, movable oil ratio, reservoir pressure coefficient, permeability, and rock brittleness index) to construct a comprehensive weighting factor, which is used to quantitatively identify a favorable shale oil reservoir. This method firstly constructs an evaluation function for each of the parameters, and then calculates a comprehensive weighting factor to determine the shale oil sweet spot. Statistical results show that the oil production of formation testing intervals have a good positive correlation with the average value of the comprehensive weighting factor of the intervals, which verifies the feasibility of the method. Based on this method, one of the key exploratory wells, Qiang21 in the Raoyang Sag of Bohai Bay basin, was selected as a case study and was determined to be a sweet spot interval of the shale oil reservoir in the upper third member of the Shahejie Formation. This study provides a new way to obtain a favorable exploration interval of shale oil reservoirs and serves shale oil development.

Mercury ions as high toxic pollutants have received wide-spread attention because of their poisonousness, persistence and enrichment. To better understand the distribution of mercury species and supplement more detailed toxicological research, it is necessary to develop some methods for monitoring mercury ions with high sensitivity and selectivity. Therefore, a simple rhodol-based highly selective fluorescent probe, RH-Hg, has been developed for monitoring Hg2+ with thiocarbamate as the recognition receptor. The probe RH-Hg can quantificationally detect mercury ions in aqueous solution assisted by hydrogen peroxide (H2O2), and it can discriminate Hg2+ through "naked-eye" observation of the color changes from light orange to dark pink. Finally, the practical applications of the probe RH-Hg in the river water further demonstrated that it will be an effective and economical tool for monitoring the distribution of Hg2+ in the environment.

A superconvergent isogeometric formulation is presented to accurately analyze the natural frequencies for elastic continua. This formulation is realized by a set of superconvergent quadrature rules which are designed for the numerical integration of isogeometric mass and stiffness matrices. In order to obtain these quadrature rules, a natural frequency error measure for elastic continua is systematically deduced using the quadratic basis functions, where the mass and stiffness matrices are formulated by the assumed quadrature rules. In contrast to the quadrature-based superconvergent isogeometric formulation for the scalar-valued wave equations, it is shown that herein different quadrature rules are required for the mass and stiffness matrices to achieve the superconvergence of natural frequency computation for the vector-valued elastic continuum problems . Consequently, the superconvergent quadrature rules are established through optimizing the natural frequency accuracy. It turns out that with these quadrature rules, the accuracy of natural frequencies for elastic continua is improved by two orders compared with the standard isogeometric formulation employing the consistent mass matrix . Meanwhile, it is found that the superconvergent quadrature rules involve the wave propagation angle and consequently simplified quadrature rules without the angle dependence are further proposed for straightforward practical applications. Numerical results reveal the superconvergence of the proposed method regarding the natural frequencies for elastic continua.

A superconvergent isogeometric method is developed for the buckling analysis of thin beams and plates, in which the quadratic basis functions are particularly considered. This method is formulated through refining the quadrature rules used for the numerical integration of geometric and material stiffness matrices. The criterion for the quadrature refinement is the optimization of the buckling load accuracy under the assumption of harmonic buckling modes for thin beams and plates. The method development starts with the thin beam buckling analysis, where the material stiffness matrix with quadratic basis functions does not involve numerical integration and thus the refined quadrature rule for geometric stiffness matrix can be obtained in a relatively easy way. Subsequently, this refined quadrature rule for thin beam geometric stiffness matrix is conveniently generalized to the thin plate geometric stiffness matrix via the tensor product operation. Meanwhile, the refined quadrature rule for the thin plate material stiffness matrix is derived by minimizing the buckling load error. It turns out that the refined quadrature rule for the thin plate material stiffness matrix generally depends on the wave numbers of buckling modes. A theoretical error analysis for the buckling loads evinces that the isogeometric method with refined quadrature rules offers a fourth-order accurate superconvergent algorithm for buckling load computation, which is two orders higher than the standard isogeometric analysis approach. Numerical results well demonstrate the superconvergence of the proposed method for the buckling loads corresponding to harmonic buckling modes, and for those related with non-harmonic modes, the buckling loads given by the proposed method are also much more accurate than their counterparts produced by the conventional isogeometric analysis.

Mercury (Hg) is a heavy metal with high toxicity and easy migration; it can be enriched through the food chain, and cause serious threats to the natural environment and human health. So, the development of a method that can be used to detect mercury ions (Hg

Early treatment is the best choice for cancer treatment. But there are many difficulties in the early diagnosis of cancer. Fluorescent probes can be used to detect small molecules or proteins overexpressed in tumor cells as a screening tool for tumor cells. However, many analytes are not specifically expressed in tumor cells. Therefore, the sensitivity and accuracy are both limited. Previous studies have shown that hydrogen peroxide (H2O2) is overexpressed in tumor cells. Similarly, melatonin can effectively bind to G-protein coupled receptors (MT1 and MT2), which are also overexpressed in some types of tumor cells. Hence, we constructed a novel melatonin-based targetable H2O2 fluorescent probe for precisely screening tumor cells. The results showed that the proposed probe can successfully detect endogenous and exogenous H2O2 in living cells and zebrafish, and accurately screen tumor cells. Importantly, this work not only proves the potential targeting capability of melatonin for tumor cells, but also provides new strategy of targeting plus activation for tumor cells screening. Moreover, the proposed probe in this work can serve as a potential tool for early diagnosis of cancer.

Hydrogen sulfide (H2S), a recognized environmental pollutant, comes from a wide range of sources. For example, H2S will be produced in the process of plant protein corruption, the decomposition of domestic sewage and garbage, food processing (wine brewing), etc. and once the concentration is too high, it will cause significant damage of environment and human body. Besides H2S is an important gas signal molecule in vivo, which can be transferred through lipid membrane. Its existence level is closely related to many diseases. If we can “visually” trace the transmembrane transmission of hydrogen sulfide, it will be very helpful for the study of oxidative stress processes, cell protection, signal transduction and related diseases closely related to H2S. Although some probes can detect H2S in environment, cytoplasm and organelles, there are few reports on the release and internalization of H2S. In this work, we report a H2S fluorescence probe that can retain on the cell membrane, named PCM. The probe PCM can not only detect endogenous and exogenous H2S, but also distinguish them, this provides a general strategy for the construction of probes to detect other biomarkers. In addition, PCM has been successfully applied to the detection of endogenous and exogenous H2S in zebrafish, which has the potential to become a new chemical tool and provide help for the research of H2S-related diseases.

In recent years, more and more chemists and biologists pay attention to the research of fluorescent probes, and great progress has been made in the design and application. In this review, we first discuss the excellent photophysical properties of 4-hydroxy-1,8-naphthalimide (HNI) structure, including excellent photostability, high fluorescence quantum yield, and easy modification of the structure. Then, by discussing the fluorescence behavior of the probe in the corresponding recognition process, the contributions of fluorescent probes built on the platform of HNI in the fields of chemical sensing, biological imaging, pharmaceutical chemistry, environment and food safety in the past ten years are systematically introduced (173 references). At the same time, we hope to develop more powerful fluorescent chemical sensors, which can play a more extensive and exciting role in the future.

In this work, an optical elements azimuth optimization method in single rotating compensator domain imaging system was provided to improve the domain image visibility. After that, simulations were performed on 200 nm permalloy films and results displayed that the Kerr rotations exhibited a periodic increase-maximum-decrease tendency with the compensator rotating in one period. The Kerr effect enhancement can be achieved by collecting the light intensity at four compensator azimuths in a rotating period of the compensator. Furthermore, simulation results indicated that this method could effectively enhance the domain image contrast and signal-to-noise ratio of the permalloy film by setting the polarizer and analyzer at the optimal azimuth. What's more, to confirm the validity of this method, simulations were performed on 200 nm optically anisotropic cobalt film. The 2D image contrast figure indicated that unlike the isotropic permalloy film, there existed two large image contrast regions which are corresponding well to the extraordinary and ordinary light vector of the reflected light.

Intelligent fault diagnosis has been a research hotspot in recent years. However, most of the works are conducted based on the hypothesis that training and testing data subject to the same distribution. In engineering scenarios, machines usually work under variable operation conditions, which results in the data from different conditions subject to distribution discrepancy. Since transfer learning is able to reuse the related knowledge across different domains, a hybrid transfer learning method (HTLM) is proposed to utilize the diagnosis knowledge obtained from one operation condition to complete the diagnosis tasks under other conditions. In the method, transfer component analysis is firstly used to extract fault features with small distribution discrepancy from the cross-domain samples. After that, the features learned from the source domain help train a classifier by Tradaboost algorithm to improve its diagnosis accuracy on the target domain. The effectiveness of the proposed method is verified by a set of laboratory bearing datasets, in which the data under one operation condition are used to help identify the health states of bearings under another condition. The results indicate that the proposed HTLM is able to achieve a higher diagnosis accuracy than other diagnosis methods.

Mercury ions as high toxic pollutants have received wide-spread attention because of their poisonousness, persistence and enrichment. To better understand the distribution of mercury species and supplement more detailed toxicological research, it is necessary to develop some methods for monitoring mercury ions with high sensitivity and selectivity. Therefore, a simple rhodol-based highly selective fluorescent probe, RH-Hg, has been developed for monitoring Hg