Systematic evolution of ligands by exponential enrichment (SELEX) is the workhorse method for selecting aptamers that are capable of binding target molecules from a random oligonucleic acid library. ...However, conventional SELEX methods are associated with apparent drawbacks including labor-intensive, time-consuming, large reagent consumption and strong nonspecific binding with separation media. Herein, we report a boronate affinity monolithic capillary-based SELEX approach for rapid selection of high-specificity glycoprotein-binding DNA aptamers. Boronate affinity monolithic capillary is an advanced functional material appeared in recent years, which allows for facile capture/release of glycoproteins in a pH-switchable fashion. By using boronate affinity monolithic capillary as a platform for target immobilization and aptamer isolation, the proposed SELEX method allowed for efficient selection of glycoprotein-binding aptamers by 6 rounds and the dissociation constants were at 10(-8) M level. Because of the employment of boronate affinity monolithic capillary, the new SELEX approach overcame the above-mentioned drawbacks and provided several significant advantages, including rapid selection speed (only 2 days were needed), high specificity toward the target molecules, and minute reagent consumption.
•A 3-pyridinylboronic acid-functionalized hybrid monolithic column was prepared.•The monolith exhibited the lowest binding pH (4.5) to date.•The monolith showed improved affinity toward negatively ...charged cis-diol compounds.•The monolith exhibited anion exchange-driven secondary separation capability.
Boronate affinity chromatography (BAC) is a unique means for the selective separation and enrichment of 1,2 and 1,3 cis-diol-containing compounds. However, conventional boronate affinity materials require a basic binding pH (usually≥8.5), which gives rise to not only inconvenience in operation but also the risk of degradation of labile compounds. Although the applicable pH has been expanded to 5.0 in recent years, the current boronate affinity materials still fail to meet the acidic pH end of frequently used biosamples, particularly urine (pH 4.5). In this study, we report a 3-pyridylboronic acid-functionalized organic–silica hybrid monolithic capillary that exhibited a binding pH of 4.5, the lowest so far in BAC. Such a binding pH enabled direct extraction of cis-diol-containing biomolecules such as nucleosides from urine samples without pH adjustment. The boronate affinity monolithic capillary showed enhanced affinity toward negatively charged cis-diol-containing analytes such as ribonucleotides. Moreover, it could function as an anion exchanger at acidic pH (∼2). The column was found to retain multiple compounds from urine, which can be assumed to be at least mostly if not entirely cis-diol-containing compounds.
Fruit tree frost, an agricultural meteorological disaster primarily occurring in spring, severely impacts the growth and development of trees and fruit set. Therefore, exploring the temperature ...change rules of fruit trees during frost events is of considerable importance. This study used a T40 unmanned aerial vehicle (UAV) as the test vehicle based on the air disturbance frost prevention principle. The airflow field change pattern of the UAV was explored using the computational fluid dynamics simulation method, and the reliability of the multi-rotor UAV in frost prevention was verified using field tests. Setting the UAV height at 6.0 m above the ground and the rotor speed at 1000 r min−1, it was found that under the conditions of the inverse temperature phenomenon, the temperatures of different altitude layers will eventually converge to a stable value when the UAV down-rotating airflow is disturbed, which could be completed rapidly within 20 s. The results of the field test also showed that when the fruit trees reached the critical temperature of frost at the flowering stage, UAV intervention could have a substantial effect on the warming of the near-surface layers, whose warming amplitude was in the range of 2.5 °C–3 °C. This study provides a reliable method for mitigating frost, which serves as an important theoretical and guiding basis for improving agricultural frost disasters in China.
•A multi-rotor UAV is used to test frost protection performance on fruit trees.•The temperature field characterizations are obtained.•The anti-frost effectiveness of UAV intervention is confirmed.
A new water-soluble anionic conjugated polyelectrolyte with a nitroxide radical covalently linked to the sulfonated poly(phenylene ethynylene) backbone (PPE-SO(3)) is reported. This ...radical-functionalized PPE-SO(3) (RF-PPE-SO(3)) demonstrates fluorescence and electron spin resonance (ESR) bimodal signaling function and shows sensitive and selective response to antioxidants.
Neural network based clustering methods usually have better performance compared to the conventional approaches due to more efficient feature extraction. Most of existing deep clustering techniques ...either exploit graph information as prior to extract pivotal deep structure from the raw data and simply utilizes stochastic gradient descent (SGD). However, they often suffer from separating the learning steps regarding dimensionality reduction and clustering. To address these issues, a novel deep model named as deep fuzzy k-means (DFKM) with adaptive loss function and entropy regularization is proposed. DFKM performs deep feature extraction and fuzzy clustering simultaneously to generate a more appropriate nonlinear feature map. Additionally, DFKM incorporates FKM so that fuzzy information is utilized to represent a clear structure of deep clusters. To further promote the robustness of the model, a robust loss function is applied to the objective with adaptive weights. Moreover, an entropy regularization is employed for affinity to provide confidence of each assignment and the corresponding membership and centroid matrices are updated by close-form solutions rather than SGD. Extensive experiments show that DFKM has better performance compared to the state-of-the-art fuzzy clustering techniques under three clustering metrics.
This study analyzes the risk involved in riding various transit modes during and after a global pandemic. The goal is to identify which factors are related to this risk, how such a relationship can ...be represented in a manner amenable to analysis, and what a transit operator can do to mitigate the risk while running its service as efficiently as possible. The resulting infection risk model is sensitive to such factors as prevalence of infection, baseline transmission probability, social distance, and expected number of human contacts. Built on this model, we formulate, analyze and test three versions of a transit operator’s design problem. In the first, the operator seeks to jointly optimize vehicle capacity and staff testing frequency while keeping the original service schedule and satisfying a predefined infection risk requirement. The second model assumes the operator is obligated to meet the returning demand after the peak of the pandemic. The third allows the operator to run more than one transit line and to allocate limited resources between the lines, subject to the penalty of unserved passengers. We find: (i) The optimal profit, as well as the testing frequency and the vehicle capacity, decreases when passengers expect to come in close contact with more fellow riders in a trip; (ii) Using a larger bus and/or reducing the testing cost enables the operator to both test drivers more frequently and allow more passengers in each bus; (iii) If passengers weigh the risk of riding bus relative to taxi, a higher prevalence of infection has a negative effect on transit operation, whereas a higher baseline transmission probability has a positive effect; (iv) The benefit of improving service capacity and/or testing more frequently is limited given the safety requirement. When the demand rises beyond the range of the capacity needed to maintain sufficient social distancing, the operator has no choice but to increase the service frequency; and (v) In the multi-line case, the lines that have a larger pre-pandemic demand, a higher penalty for each unserved passenger, or a greater exposure risk should be prioritized.
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•A new colorimetric sensor was developed using nanofiber aerogels as solid carrier.•The sensor exhibited a 3D multi-level pore structure, facilitating gas mass transfer.•The sensor ...demonstrated a rapid response (30 s) with good anti-interference ability.•Accuracy and feasibility of sensing method was confirmed by comparison with GC–MS.
Polyimide nanofiber aerogels loaded with thymol blue and hydroxylamine sulfate (TB-HAS@PI NFAs) were synthesized and employed as a novel sensor for colorimetric detection of breath acetone (BrAce). The enhancement of 3D multi-level pore structure of TB-HAS@PI NFAs for sensing performance was elucidated through systematical characterization results. Because the designed sensing system relied on the specific reaction of HAS with acetone, TB-HAS@PI NFAs exhibited a more sensitive response ability to acetone, ensuring that the colorimetric sensing detection will not be interfered by other coexisting gas in exhaled breath. Moreover, the sensor demonstrated a rapid response, with color changes quantitatively measured within 30 s of exposure to acetone gas. Importantly, the feasibility and accuracy of established method were confirmed through comparison with GC–MS. This research provided a promising strategy for daily health management of healthy people and diabetics.
The efficient and accurate detection of gallic acid (GA) is particularly important for human health. Herein, a simple and low-cost ultrasonic-assisted strategy was proposed for the preparation of ...multifunctional nanocomposite of Super-P carbon black (SPCB) nanoparticles and mesoporous silica nanoparticles (MSNs), which was used to modify the glassy carbon electrode (GCE) for the fabrication of GA electrochemical sensor (SPCB@MSNs/GCE). SPCB with pearl-chain nanostructure presented an interconnected highly conductive carbon network, which significantly improved the charge transfer efficiency. MSNs with spherical morphology and mesoporous structure exhibited uniform particle dispersion and high active surface area, which remarkably improved the surface accumulation effect of sensing electrode towards GA. Moreover, the excellent electrical conductivity of SPCB compensated for the non-conductive property of MSNs. Under the optimized condition, the electrochemical response of SPCB@MSNs/GCE sensor had a good linear relationship with GA concentration (0.5–10 μM), and the corresponding limit of detection could reach up to 4.911 nM. The fabricated nanohybrid sensor showed good reproducibility, repeatability and anti-interference property. Moreover, the satisfactory GA recoveries and RSD values were achieved for the electrochemical detection of GA in tea samples. This work provides an important reference for the highly sensitive analysis of GA in the field of food safety.
Finding novel photoinitiators with photobleaching properties suitable for long-wavelength LED light sources is important for their potential use in the photocuring ceramic suspensions containing ...acrylate resin. Two D-π-A-π-D conjugated benzylidene ketones with visible light absorption (TPAK and CZK) were synthesized and evaluated as photoinitiators in the photocuring of acrylate resin and ceramic suspension under blue (460 nm)/green (520 nm) LED sources. Results showed that the two photoinitiators have high photoinitiating activity and can effectively produce thick-layer curing in acrylate resin and ceramic suspension due to their quick photobleaching properties under 460 nm and 520 nm LED light sources. The curing depth of the ceramic suspensions was measured as a function of the concentration of TPAK and CZK and the energy level of the LED light source. Jacob's equation was used to determine the critical energy Ec and depth sensitivity Dp of every suspension with different concentrations of benzylidene ketones.
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•Novel photoinitiators with photobleaching properties were found.•They showed novel activity in the photocuring of ceramic suspension under blue/green LED.•Deep curing was obtained by using these photoinitiators.
•A new molecular imprinting graphene nanocomposite (PIL-MIP/GO) was synthesized.•PIL-MIP/GO has fast mass transfer, rich adsorption mechanism, and high selectivity.•A HPLC-UV method for β-agonists ...was designed based on PIL-MIP/GO as PT-SPE sorbent.•The method was successfully applied to detect β-agonist in swine urine.•The analytical method was sensitive, selective, accurate, nonfatal, and economical.
The illegal use of β-agonists often endangers animal-derived food safety. In this study, a selective detection method for β-agonists in swine urine was established via the combination of polymeric ionic liquid-molecularly imprinted graphene oxide-miniaturized pipette tip solid-phase extraction and high-performance liquid chromatography. It is worth noting that this method relied mainly on the designed adsorbent, which presented a rich adsorption mechanism, fast mass transfer rate, and high selectivity, and was successfully utilized in the selective extraction of β-agonists from swine urine samples. The proposed method has low LOD (0.20–0.56 ng/mL), high recovery (94.9–107.9%), and high reusability (4 times, 91.9–108.8%), which indicates its high potential as a selective, sensitive, accurate, and nonfatal method for monitoring the illegal use of β-agonists in the livestock breeding stage.
