On-site rapid detection of multiple pesticide residues in tea leaves by lateral flow immunoassay

The application of pesticides (mostly insecticides and fungicides) during the tea-planting process will undoubtedly increase the dietary risk associated with drinking tea. Thus, it is necessary to ascertain whether pesticide residues in tea products exceed the maximum residue limits. However, the complex matrices present in tea samples comprise a major challenge in the analytical detection of pesticide residues. In this study, nine types of lateral flow immunochromatographic strips (LFICSs) were developed to detect the pesticides of interest (fenpropathrin, chlorpyrifos, imidacloprid, thiamethoxam, acetamiprid, carbendazim, chlorothalonil, pyraclostrobin, and iprodione). To reduce the interference of tea substrates on the assay sensitivity, the pretreatment conditions for tea samples, including the extraction solvent, extraction time, and purification agent, were optimized for the simultaneous detection of these pesticides. The entire testing procedure (including pretreatment and detection) could be completed within 30 min. The detected results of authentic tea samples were confirmed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), which suggest that the LFICS coupled with sample rapid pretreatment can be used for on-site rapid screening of the target pesticide in tea products prior to their market release.

Design and Performance Analysis of HMDV Dynamic Inertial Suspension Based on Active Disturbance Rejection Control

This paper addresses the impact of vertical vibration negative effects,unbalanced radial forces generated by the static eccentricity of the hub motor,and road excitation on the suspension performance of Hub Motor Driven Vehicle(HMDV).A dynamic inertial suspension based on Active Disturbance Rejection Control(ADRC)is proposed,combining the vertical dynamic characteristics of dynamic inertial suspension with the features of ADRC,which distinguishes between internal and external disturbances and arranges the transition process.Firstly,a simulation model of the static eccentricity of the hub motor is established to simulate the unbalanced radial electromagnetic force generated under static eccentricity.A quarter-vehicle model of an HMDV with a controllable dynamic inertial suspension is then constructed.Subsequently,the passive suspension model is studied under different grades of road excitation,and the impact mechanism of suspension performance at speeds of 0–20 m/s is analyzed.Next,the three main components within the ADRC controller are designed for the second-order controlled system,and optimization algorithms are used to optimize its internal parameters.Finally,the performance of the traditional passive suspension,the PID-based controllable dynamic inertial suspension,and the ADRC-based controllable dynamic inertial suspension are analyzed under different road inputs.Simulation results show that,under sinusoidal road input,the ADRC-based controllable dynamic inertial suspension exhibits a 52.3%reduction in the low-frequency resonance peak in the vehicle body acceleration gain diagram compared to the traditional passive suspension,with significant performance optimization in the high-frequency range.Under random road input,the ADRC-based controllable dynamic inertial suspension achieves a 29.53%reduction in the root mean square value of vehicle body acceleration and a 14.87%reduction in dynamic tire load.This indicates that the designed controllable dynamic inertial suspension possesses excellent vibration isolation performance.

聚酰亚胺气凝胶的制备及结构与性能研究进展

气凝胶是一种具有三维纳米多孔网络的固体材料,其孔隙中分布着气态介质。气凝胶具有低密度、高孔隙率和低热导率的特点,广泛应用于航空航天、电子通讯、阻燃隔热、储能、吸附、催化及传感等领域。文中调研了近年来聚酰亚胺气凝胶的相关研究进展,讨论了聚酰亚胺气凝胶的制备、结构与功能的关系等,指出未来发展聚酰亚胺气凝胶可以从提高力学强度、降低热导率方面入手,为聚酰亚胺气凝胶在隔热等领域中的应用提供参考。

核光谱望远镜阵列河外巡天:扩展钱德拉南天与钱德拉北天深场星表

我们提出一种常规且可靠的方法以获得核光谱望远镜阵列在扩展钱德拉南天深场与钱德拉北天深场的星表。核光谱望远镜阵列在扩展钱德拉南天深场的观测天区覆盖了30'×30'大小的面积,其最深曝光时长在3-24 keV波段作晕影修正后可达230 ks,共有58个源被探测到并收录在本工作的星表中;核光谱望远镜阵列在钱德拉北天深场的观测天区覆盖了7'×10'大小的面积,其最深曝光时长在3-24 keV波段作晕影修正后可达440 ks,共有42个源被首次探测到并收录在本工作的星表中。通过与钱德拉X射线天文台在对应天区的星表结果进行交叉匹配后,我们发现核光谱望远镜阵列星表中的源与它们在钱德拉X射线望远镜星表中的对应体有着大致相当的流量,由此验证了本工作两个星表的可靠性。我们的两个星表通过完全一致的方法制作而成且公开释放,这为后续涉及这两个天区的研究提供了一个统一的平台。我们的源探测方法为核光谱望远镜阵列其他河外巡天的星表制作提供了一种系统的方法。

Simulation Design of Baseband Optimal Digital Communication System with Non-Ideal Channel

This paper aims to discuss how to effectively suppress intersymbol interference by optimizing the filter design, so as to achieve a distortion-free output effect, and effectively compensate the transmission characteristics of the baseband transmission system in a non-ideal channel environment, so as to minimize the impact of intersymbol crosser. The simulation experiment model of digital optimal baseband transmission and the overall structure of the system are designed based on the Matlab simulation platform, and the parameters of each module in the simulation experiment model are set. The working process and performance of the digital optimal baseband transmission system are simulated, and the conditions and performance of the digital optimal baseband transmission system are verified according to the simulation results.

明矾的宏观晶体形状

通过简易的热力学模型推测晶体宏观形状及缺陷的成因,借助于本科无机探究实验,培养明矾大晶体并测量其宏观参数,拟合出明矾的热力学参数,以解释明矾的宏观形状、缺陷并预测明矾的完美八面体的可能性与晶体的自范性。

Generative Adversarial Network Based Heuristics for Sampling-Based Path Planning

Sampling-based path planning is a popular methodology for robot path planning.With a uniform sampling strategy to explore the state space,a feasible path can be found without the complex geometric modeling of the configuration space.However,the quality of the initial solution is not guaranteed,and the convergence speed to the optimal solution is slow.In this paper,we present a novel image-based path planning algorithm to overcome these limitations.Specifically,a generative adversarial network(GAN)is designed to take the environment map(denoted as RGB image)as the input without other preprocessing works.The output is also an RGB image where the promising region(where a feasible path probably exists)is segmented.This promising region is utilized as a heuristic to achieve non-uniform sampling for the path planner.We conduct a number of simulation experiments to validate the effectiveness of the proposed method,and the results demonstrate that our method performs much better in terms of the quality of the initial solution and the convergence speed to the optimal solution.Furthermore,apart from the environments similar to the training set,our method also works well on the environments which are very different from the training set.

Ultrastructure of human neural stem/progenitor cells and neurospheres

BACKGROUND： Biological and morphological characteristics of neural stem/progenitor cells （NSPCs） have been widely investigated. OBJECTIVE： To explore the ultrastructure of human embryo-derived NSPCs and neurospheres cultivated in vitro using electron microscopy. DESIGN, TIME AND SETTING： A cell biology experiment was performed at the Brain Tumor Laboratory of Soochow University, and Jiangsu Province Key Laboratory of Neuroregeneration, Nantong University between August 2007 and April 2008. MATERIALS： Human fetal brain tissue was obtained from an 8-week-old aborted fetus; serum-free Dulbecco＇s modified Eagle＇s medium/F12 culture medium was provided by Gibco, USA; scanning electron microscope was provided by Hitachi Instruments, Japan; transmission electron microscope was provided by JEOL, Japan. METHODS： NSPCs were isolated from human fetal brain tissue and cultivated in serum-free Dulbecco＇s modified Eagle＇s medium/F12 culture medium. Cells were passaged every 5-7 days. After three passages, NSPCs were harvested and used for ultrastructural examination. MAIN OUTCOME MEASURES： Ultrastructural examination of human NSPCs and adjacent cells in neurospheres. RESULTS： Individual NSPCs were visible as spherical morphologies with rough surfaces under scanning electron microscope. Generally, they had large nuclei and little cytoplasm. Nuclei were frequently globular with large amounts of euchromatin and a small quantity of heterochromatin, and most NSPCs had only one nucleolus. The Golgi apparatus and endoplasmic reticulum were underdeveloped; however, autophagosomes were clearly visible. The neurospheres were made up of NSPCs and non-fixiform material inside. Between adjacent cells and at the cytoplasmic surface of apposed plasma membranes, there were vesicle-like structures. Some membrane boundaries with high permeabilities were observed between some contiguous NSPCs in neurospheres, possibly attributable to plasmalemmal fusion between adjacent cells. CONCLUSION： A large number of autophagosomes were observed in NSPCs and gap junctions were visible between adjacent NSPCs.

Induced neuronal differentiation of neural stem cells by a combination of cytokines One-step versus two-step methods

BACKGROUND： A combination of basic fibroblast growth factor （bFGF）, platelet-derived growth factor （PDGF）, human heregulin-beta-1, beta-mercaptoethanol retinoic acid and forskolin has been reported to induce the differentiation of rat bone marrow stromal cells into myelinating Schwann-like cells. OBJECTIVE： To investigate the inducing effects of a combination of bFGF, PDGF, human heregulin-beta-1, beta-mercaptoethanol retinoic acid and forskolin on neural stem cell differentiation by one- and two-step methods. DESIGN, TIME AND SETTING： A cytobiology experiment was performed at the Department of Histology and Embryology, Medical School of Nantong University, and Jiangsu Province Key Laboratory of Neuroregeneration, China, between August 2005 and January 2007. MATERIALS： A total of 30 healthy Sprague Dawley rat embryos at gestational days 14-16 were selected, bFGF, PDGF, human heregulin-beta-t, beta-mercaptoethanol, retinoic acid, and forskolin were purchased from Sigma, USA. METHODS： Passage 3 rat neural stem cells were cultured by a one-step method in serum-free medium plus 10 ng/m/bFGF, 5 ng/mL PDGF, 200 ng/mL heregulin-beta-1,35 ng/mL all-trans retinoic acid, and 5 pmol/L forskolin or by a two-step method in serum-free medium plus 35 ng/m/ all-trans retinoic acid for 72 hours, followed by serum-free medium plus 10 ng/mL bFGF, 5 ng/mL PDGF, 200 ng/mL heregulin-beta-t and 5 μmol/L forskolin. The control condition consisted of 10% fetal bovine serum alone or 20 ng/mL bFGF alone. MAIN OUTCOME MEASURES： Differentiated cells were identified by immunocytochemical staining for microtubule associate protein-2 （MAP2） and St 00 protein. Geometric parameters and sodium ion currents of the differentiated cells were measured by image analysis and whole-cell patch-clamp techniques, respectively. RESULTS： Compared with the two-step culture method, neuronal-like cells exhibited longer processes and a similar appearance to mature neurons using the one-step method. The percentage of MAP2 positive cells induced by the one-step method was significantly greater than the serum-alone group （P 〈 0.05）. Furthermore, the MAP2 positive cells induced by the one-step method had greater surface areas, cell body perimeters, and longer process than cells induced by serum-alone and bFGF-alone （P 〈 0.05）. There were no significant differences in these parameters between the one-step and two-step methods （P 〉 0.05）. In addition, 80% of the induced neuronal-like cells from the one-step method and 20% from the two-step method displayed inwardly-evoked currents. CONCLUSION： The combination of bFGF, PDGF, human heregulin-beta-t, beta-mercaptoethanol retinoic acid and forskolin successfully induced neuronal differentiation from neural stem cells, with the one-step induction being more effective than the two-step method.

Discussion on Construction of Henan Cultural Products about Geotourism

With the construction and development of Geoparks,geo-tourism culture is brought into being. Based on the significance of geotourism cultural product system,this article summarizes the natural heritage properties and scientific cultural value of Henan geological heritage resources and landscape resources,points out the various risks in construction of geo-tourism culture,such as the uncertainty of geo-tourism resources and their distribution areas,the uncertainty of the Geoparks building policies from governments,etc. ,and finally proposes some constructive suggestions and measures to avoid these risks.

Error Probability for Convolutional Codes with Weight Enumerating Function

The paper introduces the state reduction algorithm and accelerated state reduction algorithm are used to compute the distance weight enumerator(transfer function) T[x,y] of convolutional codes.Next use computer simulation to compare upper bound on the bit error probability on an additive white Gaussian noise (AWGN) for maximum free distance (MFD) codes of previously found and optimum distance spectrum (ODS) codes with rate 1/4,overall constraint length are 5 and 7,respectively. Finally,a method of how to search for good convolutional codes is given.

Internal flow in sessile droplets induced by substrate oscillation:towards enhanced mixing and mass transfer in microfluidic systems

The introduction of flows within sessile droplets is highly effective for many lab-on-a-chip chemical and biomedical applications.However,generating such flows is difficult due to the typically small droplet volumes.Here,we present a simple,non-contact strategy to generate internal flows in sessile droplets for enhancing mixing and mass transport.The flows are driven by actuating a rigid substrate into oscillation with certain amplitude distributions without relying on the resonance of the droplet itself.Substrate oscillation characteristics and corresponding flow patterns are documented herein.Mixing indices and mass transfer coefficients of sessile droplets on the substrate surface are measured using optical and electrochemical methods.They demonstrate complete mixing within the droplets in 1.35 s and increases in mass transfer rates of more than seven times static values.Proof of concept was conducted with experiments of silver nanoparticle synthesis and with heavy metal ion sensing employing the sessile droplet as a microreactor for synthesis and an electrochemical cell for sensing.The degrees of enhancement of synthesis efficiency and detection sensitivity attributed to the internal flows are experimentally documented.

Adeno-associated virus-mediated intraprostatic suppression of MIR375 inhibits tumor progression in the TRAMP mouse nmodel of prostate cancer

The treatment of prostate cancer(PCa)needs to be improved.1 Micro-RNAs(miRNAs)are a subtype of non-coding,single-stranded RNAs that influence cellular survival and death by modulating mRNAs.Among these miRNAs,MIR375 has a critical role in the regulation of tumorigenesis?and holds promise as a novel therapeutic target for future PCa treatment.Recombinant adeno-associated virus(rAAV)exhibits non-pathogenicity,low-grade inflammation,and robust and long-lasting expressions of target genes.We have previously described the rAAv9 as a valid vector to transfer target miRNAs and genes,3 so rAAv9 could be used as a vector to deliver MIR375 into the mouse prostate and PCa cells.

Study on myocardial infarction based on nationwide inpatient sample database:a bibliometric analysis from 2000 to 2022

Background:Studies on myocardial infarction(MI)based on large medical databases have become popular in recent years.The influence of the National Inpatient Sample(NIS),the largest collection of administrative healthcare data across the United States,on the field of MI has not been well investigated.This study aimed to quantify the contribution of NIS to MI research using bibliometric methods.Methods:We searched the Web of Science Core Collection database to identify publications on MI using NIS from 2000 to 2022.Bibliometric indicators,such as the number of publications,citations,and Hirsch index(H-index),were summarized by years,authors,organizations,and journals.VOSviewer and CiteSpace software were used to analyze the keywords and trends of the hot spots.Results:A total of 342 articles on MI based on NIS were included.A significant growth in outputs related to MI using the NIS from 2000 to 2020 was observed.The publications were mainly from the United States.The Mayo Clinic was the most prolific institution and had the most citations and the highest H-index.The American Journal of Cardiology ranked first among journals with the highest number of publications,citations,and H-index.Mortality and healthcare management are the main focuses of this field.Personalized risks and care are receiving increased attention.Conclusion:This study suggests that NIS significantly contributes to high-quality output in MI research.More efforts are needed to improve the impact of knowledge gained from the NIS on MI.

基于网球拍材料的演进探讨未来网球拍发展前景

网球拍的发展历史与材料科学紧密相连。从木质拍框到现代的碳纤维复合材料,每一次材料的革新都伴随着网球拍性能的飞跃。本文从化学的角度出发,探讨了不同材料的化学特性如何决定了网球拍的性能,并对网球拍材料的未来发展趋势进行展望。

MultiTrans:Multi-scale feature fusion transformer with transfer learning strategy for multiple organs segmentation of head and neck CT images

Radiotherapy with precise segmentation of head and neck organs at risk(OARs)is one of the important treatment methods for head and neck cancer.In routine clinical practice,OARs are manually segmented by doctors to avoid irreversible adverse reactions caused by radiotherapy,which is time-consuming and laborious.To assist doctors in OARs segmentation,a MultiTrans framework with a multi-scale feature fusion module was proposed in this paper.In the multi-scale feature fusion module,the original image and the feature map of CNN were fused together to form a compound feature map for more complete high-resolution global information.In addition,the global information was also fully utilized in MultiTrans by using the feature map restored from the compound feature map in the skip connection.The multi-scale interactive high-resolution information can make full use of medical image information and obtain features more comprehensively,thus improve the segmentation accuracy.Experiments showed that MultiTrans had an average Dice score coefficient(DSC)of 74.01%in all organs,effectively improved segmentation accuracy.In addition,we proposed a transfer learning strategy for small organs by transferring the weight parameters of organs with a large amount of data to organs with a small amount of data to speed up the convergence of MultiTrans and reduce the demand for data volume in the MultiTrans.With this strategy,the average DSC of small organs was obviously increased,making the segmentation of small organs more accurate.The proposed framework and transfer learning strategy have the potential of assisting doctors in OARs delineation.

基于扎根理论的零工参与动机演化机制研究——以平台司机为例

零工经济模式下平台型企业出现了迅猛发展,但是通过分析平台工作者持续参与行为的动机从而提出有针对性的引导策略是目前研究中缺乏深入探讨的议题。本文以419个滴滴司机作为样本,采用扎根理论的编码原则运用NVivo 11 Plus软件对参与平台劳动的滴滴司机进行访谈,总结出了平台司机的参与动机演化机制。基于自我决定理论的观点,我们发现:平台司机个体心理感知的满足程度是促进外部动机向内部动机转化的关键;经济效益对平台司机参与行为的影响最大,自主感知在动机转化过程中起关键作用;经济效益对兼职司机参与行为的影响更大,专职司机的内部动机低于兼职司机,自主感知在专职司机动机内化过程中所起的促进作用更大。本研究扩展了自我决定理论在零工经济模式下对动机演化机制的解释,研究结论为零工工人的激励提供了新的理解。

天问一号火星探测器着陆点快速精确定位

为实现天问一号着陆点快速精确定位,规划火星车行驶路径,并将火星车后续数据纳入统一的地理坐标系,本研究利用着陆初期有限数据(天问一号环绕器获取的遥感影像、一幅悬停避障缓速下降阶段的GNC(guidance,navigation and control)避障敏感器拍摄的降落影像和导航相机在着陆平台的环拍立体像对)完成定位任务.首先,通过导航相机的环拍影像生成着陆点周围陨石坑、沙丘、火山口、山梁之间的拓扑关系.然后,以根据环绕器的遥感影像生成的数字正射影像图(digital orthophoto map,DOM)为底图,将导航相机生成的陨石坑、沙丘、火山口、山梁之间的拓扑关系与底图预着陆区的陨石坑、沙丘、火山口、山梁之间的拓扑关系进行模糊匹配,以确定疑似着陆点,并结合降落影像在疑似着陆点中确定着陆点的粗略位置.最后,根据导航相机影像多像空间后方交会解算着陆点的精确位置为109.925°E,25.066°N.

Evolution of rust layers on carbon steel and weathering steel in high humidity and heat marine atmospheric corrosion

The evolution of the rust layers on carbon steel and weathering steel in high humidity and heat marine atmospheric environment was investigated by wet/dry cyclic acceleration corrosion tests in this study.The corrosion process of carbon steel and weathering steel was divided into two stages and the reasons for the changes in the corrosion rates of two steels were different.The composition phase of the inner rust layer of weathering steel was mainly goethite,whereas that of carbon steel was mainly akaganeite.Rust resistance(Rr)performed better than charge transfer resistance(Rt)in evaluating the protection performance of rust layer.As the corrosion proceeded,the evolution of the cathodic process of weathering steel was not obvious,whereas that of carbon steel was irregular.

Enhancing the mechanical and anticorrosion properties of 316L stainless steel via a cathodic plasma electrolytic nitriding treatment with added PEG

A cathodic plasma electrolytic nitriding(CPEN)treatment with a urea aqueous solution was performed on 316L stainless steel to rapidly improve its surface properties in this work.Test results show that the PEG2000 macromolecules increased the nitriding energy via enhancing the ability to bond the produced gas film to the metal/electrolyte interface.The cross-sectional morphologies indicate that a thick nitrided layer was obtained when the urea concentration was 543 g I^-1,corresponding to a Vickers hardness 450 HV(0.1),which was 3.5 times larger than that of the substrate.The nitrided layer mainly contained expanded austenite(γN),oxides and iron nitrides(e.g.,Fe3O4 and FeN(0.076)).In terms of its performance,coefficient of friction(COF)of the nitride layer decreased to nearly two-thirds that of the untreated layer,and the passivation current densities of the nitrided sample in a 3.5%NaCl solution decreased by an order of magnitude compared to that of the substrate.Therefore,the approach presented herein provides an attractive way to modify the effect of CPEN in a urea aqueous solution.