A mimicking-enzyme-based colorimetric aptasensor was developed for the detection of kanamycin (KANA) in milk using magnetic loop-DNA-NMOF-Pt (m-L-DNA) probes and catalytic hairpin assembly ...(CHA)-assisted target recycling for signal amplification. The m-L-DNA probes were constructed via hybridization of hairpin DNA H1 (containing aptamer sequence) immobilized magnetic beads (m-H1) and signal DNA (sDNA, partial hybridization with H1) labeled nano Fe-MIL-88NH
-Pt (NMOF-Pt-sDNA). In the presence of KANA and complementary hairpin DNA H2, the m-L-DNA probes decomposed and formed an m-H1/KANA intermediate, which triggered the CHA reaction to form a stable duplex strand (m-H1-H2) while releasing KANA again for recycling. Consequently, numerous NMOF-Pt-sDNA as mimicking enzymes can synergistically catalyze 3,3',5,5'-tetramethylbenzidine (TMB) for color development. The aptasensor exhibited high selectivity and sensitivity for KANA in milk with a detection limit of 0.2 pg mL
within 30 min. The assay can be conveniently extended for on-site screening of other antibiotics in foods by simply changing the base sequence of the probes.
College students have gradually become the main force of entrepreneurship in mass entrepreneurship and innovation. However, their entrepreneurial performance was not as good as expected. We have ...carried out research to analyze the predictive factors of entrepreneurial performance of college students and put forward targeted suggestions, hoping to be helpful to improve their entrepreneurial performance of them. Based on questionnaire data obtained from 2,097 college student entrepreneurs, this study uses the structural equation model to analyze the predictive factors of the entrepreneurial performance of college students. The survey results of the questionnaire show that both personal and behavioral factors influence the entrepreneurial performance of college students. In this study, personal factors in this study mainly include entrepreneurial willingness, personality, and ability of entrepreneurs. Behavioral factors mainly refer to the positive behaviors of entrepreneurs that can affect entrepreneurial performance.
•A cucumber canopy vine top recognition algorithm based on YOLOv5 is proposed.•The cucumber canopy vine top recognition performance of improved algorithm is analyzed and compared.•The recognition ...performance of the improved algorithm is verified via instance recognition.•The improved algorithm has good recognition performance for the cucumber canopy vine tops.
In order to solve the problem of low recognition accuracy of cucumber canopy vine tops image caused by the high density and intermingling of the cucumber canopy vine, an image recognition model of cucumber canopy tops based on the deep learning model of improved YOLOv5 is proposed in this paper. A combination of online and offline augmentation is used to amplify the original data to ensure a balanced number of images in different types of datasets during training and testing. Considering the small leaves characteristics of the cucumber canopy vine tops, the CA mechanism module (YOLOv5-CA) is introduced into the backbone network of the YOLOv5 model to improve the recognition accuracy of the small leaf target. On this basis, the regression Loss GIOU of the target position was changed to EIOU and the cross-entropy function of confidence loss was changed to Focal Loss function (YOLOv5-CA-LS) to reduce the influence of the imbalance of difficult and easy samples on the detection results. The models before and after optimization were compared. The results show that compared with the YOLOv5 model, the accuracy, recall rate, mAP@0.5 and mAP@0.5:0.95 of the YOLOv5-CA-LS model is improved by 4.4%, 5.0%, 1.3% and 1.8% respectively. And average recognition accuracy value of the instance of the cucumber canopy tops adopted the YOLOv5-CA-LS model is 97.1% under different angle and cloudy conditions, which can meet the recognition requirement of high density and intermingling of the cucumber canopy vine tops.
Bolted flange joints are commonly utilized in engineering constructions; nevertheless, their dynamic behavior is complicated when nonlinearity is present. The bolted flange joint structure in this ...research is considered as a spring-mass system, and the equivalent axial two bi-linear springs-bending beam model, as well as the system's vibration control equation, is created to examine the joint structure's vibration characteristics under transverse stress. The results indicate that when the spring stiffness is constant and the stiffness is a linear function of displacement, and the mass matrix of the vibration control equation is coupled, the system produces only transverse vibration upon transverse impact; when the spring axial stiffness is a linear function of displacement and the mass matrix of the vibration control equation is not coupled, the spring stiffness is bilinear and the stiffness is a quadratic function of displacement, the system will vibrate transversely and longitudinally under the transverse impact. Regardless of how the spring stiffness is simplified, the system's transverse or transverse and axial movement is a stable periodic vibration with a vibration response proportional to the system's mass and the radius L of the connected cylindrical shell.
► Using Fe3O4@GO as the sorbent of MSPE. ► The first time using Fe3O4@GO to adsorb trace levels of PCBs in water samples. ► Investigation of Fe3O4@GO’s adsorption characteristics and sorption ...isotherm. ► Establishment of a highly selective and sensitive MSPE–GC–MS analytical method.
In this paper, Fe3O4 nanoparticle (Fe3O4 NPs) grafted graphene oxide (Fe3O4@GO), are successfully synthesized and used for the extraction of 2,4,4′-trichlorobiphenyl (PCB 28) from a large volume of water solution. With the magnetic solid-phase extraction (MSPE) technique based on the Fe3O4@GO sorbents, it requires only 30min to extract trace levels of PCB 28 from 200mL water samples. The Fe3O4@GO was analyzed by using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier Transform infrared (FT-IR) spectroscopy, and Vibrating sample magnetometer (VSM), specific surface area analyzer. The adsorption kinetics, adsorption capacity of the adsorbent, and the effect of the solution pH and desorption conditions on the removal efficiency of PCB 28 were investigated. The second-order kinetic equation best describes the sorption kinetics. The results showed that Fe3O4@GO was a suitable material in the pre-concentration and immobilization of PCB 28 from large volumes of aqueous solutions in polychlorinated biphenyl pollution cleaning.
Soil fertility is vital for the growth of tea plants. The physicochemical properties of soil play a key role in the evaluation of soil fertility. Thus, realizing the rapid and accurate detection of ...soil physicochemical properties is of great significance for promoting the development of precision agriculture in tea plantations. In recent years, spectral data have become an important tool for the non-destructive testing of soil physicochemical properties. In this study, a support vector regression (SVR) model was constructed to model the hydrolyzed nitrogen, available potassium, and effective phosphorus in tea plantation soils of different grain sizes. Then, the successful projections algorithm (SPA) and least-angle regression (LAR) and bootstrapping soft shrinkage (BOSS) variable importance screening methods were used to optimize the variables in the soil physicochemical properties. The findings demonstrated that soil particle sizes of 0.25–0.5 mm produced the best predictions for all three physicochemical properties. After further using the dimensionality reduction approach, the LAR algorithm (R2C = 0.979, R2P = 0.976, RPD = 6.613) performed optimally in the prediction model for hydrolytic nitrogen at a soil particle size of 0.25~0.5. The models using data dimensionality reduction and those that used the BOSS method to estimate available potassium (R2C = 0.977, R2P = 0.981, RPD = 7.222) and effective phosphorus (R2C = 0.969, R2P = 0.964, RPD = 5.163) had the best accuracy. In order to offer a reference for the accurate detection of soil physicochemical properties in tea plantations, this study investigated the modeling effect of each physicochemical property under various soil particle sizes and integrated the regression model with various downscaling strategies.
•Characterization of magnetic molecularly imprinted polymer (MMIP).•Developments and evaluation of MMIP as a stationary phase for automated SPME system.•MMIP coatings displayed excellent extraction ...performance for four estrogens.•The coatings demonstrated extraction capacity, reusability and reproducibility.
A new automated solid-phase micro extraction (SPME) sampling method was developed for quantitative enrichment of estrogens (ES) from milk powder, using magnetic molecularly imprinted polymer (MMIP) as fiber coating. The method (MMIP-SPME) was built with several electromagnetic stainless steel fibers, placed in parallel for simultaneously extraction. The MMIP was synthesized using core–shell Fe3O4@SiO2 nanoparticles (NPs) as magnetic support. Estradiol (E2) was employed as the template molecule, acrylamide (AA) as functional monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. MMIP can be easily absorbed or desorbed from fibers when the current is turned on or off, creating magnetism. Compared to traditional MIP-SPME, the prepared procedure of MMIP-SPME is time-saving and organic solvent-free. The proposed device significantly improved the efficiency of separation and enrichment of estrogens from complex matrices thereby and facilitating the pretreatment steps by electromagnetically controlled extraction fibers to achieve full automation. Several experimental parameters were studied, including extraction and desorption kinetics, solution pH, desorption solution, ratio, and shuttle rate. The newly developed MMIP-SPME showed good sensitivity and high binding capacity, fast adsorption kinetics and desorption kinetics for estrone (E1), estradiol (E2), estriol (E3) and diethylstilbestrol (DES) under optimized conditions. The detection limits for the four estrogens were 1.5–5.5ngg−1 with excellent reproducibility (RSD values less than 7.1%) when milk powder samples spiked with analytes at 20, 100 and 250ngg−1 were studied.
In this report, a rapid and cost-effective sandwich electrochemiluminescence (ECL) immunosensor was constructed for the ultrasensitive detection of human immunodeficiency virus type 1 antibody ...(anti-HIV-1) using magnetic molecularly imprinted polymers (MMIPs) as capture probes by combining surface and epitope imprinting techniques and antigen conjugated with horseradish peroxidase (HRP-HIV-1) as labels. First, 3-aminobenzeneboronic acid (APBA) was used as the functional monomer and cross-linking reagent, which was polymerized on the surface of silicate-coated magnetic iron oxide nanoparticles (Fe3O4@SiO2 NPs) in the presence of human immunoglobulin G (HIgG), as the template exhibiting the same Fc region but different Fab region to anti-HIV-1 after the addition of the initiator, ammonium persulfate. This process resulted in grafting a hydrophilic molecularly imprinted polymer (MIP) film on the Fe3O4@SiO2 NPs. Thus, MMIPs, which could be reused after eluting the template, were used to recognize and enrich ultra-trace levels of anti-HIV-1. Subsequently, a novel sandwich ECL immunosensor was formed through the immunoreaction between MMIPs conjugated with varied concentrations of anti-HIV-1 and HRP-HIV-1. By the catalysis of HRP immobilized onto HRP-HIV-1 on the ECL system of Luminol-H2O2, a linear response range of the anti-HIV-1 dilution ratio (standard positive serum) was achieved from 1:20,000 to 1:50, with a detection limit of 1:60,000 (S/N=3). The developed method provides a low-cost, simple, and sensitive way for the early diagnosis of HIV infected patients.
•A rapid and cost-effective sandwich electrochemiluminescence (ECL) immunosensor was fabricated using magnetic molecularly imprinted polymers (MMIPs) as capture probes.•Using MMIPs as capture probes to construct ECL immunosensor could largely lower the cost and improve the stability.•MMIPs could simplify the preparation and provide regenerate steps for the sensor.•MMIPs could enrich ultratrace antibodies and thus achieve ultrasensitive assay.•A new immunoassay for protein detection was created.
Incomplete Kawasaki disease (IKD) is characterized by a longer fever time, younger age of onset, and higher incidence of coronary artery disease compared with complete Kawasaki disease. Kawasaki ...disease is often difficult to diagnose early because of its incomplete clinical symptoms. This issue could delay treatment and harm the health of the child. This article reviews the clinical characteristics and pathogenesis of IKD to help clinicians understand the symptoms of IKD, make the correct diagnosis, and provide timely treatment.
Neurospecific Enolase (NSE), a multifunctional protein, is present in various tissues of the body and plays an important role in many disease processes, such as infection, inflammation, tumours, ...injury, and immunity. In recent years, the application of NSE in respiratory diseases has become increasingly widespread and a research hotspot.
This study aims to explore the relationship between NSE and childhood pneumonia, providing assistance for the diagnosis and assessment of pneumonia.
Using prospective research and case-control methods, We selected 129 children with pneumonia hospitalised in Weifang People's Hospital from September 2020 to April 2022 as the case group. Among them were 67 cases of Mycoplasma pneumoniae pneumonia (MP+), 62 cases of non-Mycoplasma pneumoniae pneumonia (MP -), and 21 cases of severe pneumonia. At the same time, 136 children who underwent outpatient health examinations were selected as the control group. The levels of NSE, ESR, CRP in cases group and NSE in control group were measured separately.
The NSE levels in the MP + group were 17.86 (14.29-22.54) ng/mL, while those in the MP- group were 17.89 (14.10-21.66) ng/mL, both of which were higher than the control group's NSE levels of 13.26(12.18,14.44) ng/mL (H = 46.92, P = 0.000). There was no statistically significant difference in NSE levels between the MP + and MP - groups (P > 0.05). The NSE level in the severe pneumonia group was 27.38 (13.95-34.06) ng/mL, higher than that in the mild pneumonia group, which was 17.68 (14.27-21.04) ng/mL, (P = 0.024). The AUC values for diagnosing pneumonia are NSE0.714, CRP0.539, and ESR0.535, with NSE having the highest diagnostic value.
Serum NSE can serve as an inflammatory indicator for paediatric pneumonia, which has important clinical guidance significance for the diagnosis, condition evaluation, and prognosis of paediatric pneumonia.
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