Paper-based electrochemical sensors have the characteristics of flexibility, biocompatibility, environmental protection, low cost, wide availability, and hydropathy, which make them very suitable for ...the development and application of biological detection. This work proposes electrospun cellulose acetate nanofiber (CA NF)-decorated paper-based screen-printed (PBSP) electrode electrochemical sensors. The CA NFs were directly collected on the PBSP electrode through an electrospinning technique at an optimized voltage of 16 kV for 10 min. The sensor was functionalized with different bio-sensitive materials for detecting different targets, and its sensing capability was evaluated by CV, DPV, and chronoamperometry methods. The test results demonstrated that the CA NFs enhanced the detection sensitivity of the PBSP electrode, and the sensor showed good stability, repeatability, and specificity (
< 0.01,
= 3). The electrochemical sensing of the CA NF-decorated PBSP electrode exhibited a short detection duration of ∼5-7 min and detection ranges of 1 nmol mL
-100 μmol mL
, 100 fg mL
-10 μg mL
, and 1.5 × 10
-10
CFU mL
and limits of detection of 0.71 nmol mL
, 89.1 fg mL
, and 30 CFU mL
for glucose, Ag85B protein, and
, respectively. These CA NF-decorated PBSP sensors can be used as a general electrochemical tool to detect, for example, organic substances, proteins, and bacteria, which are expected to achieve point-of-care testing of pathogenic microorganisms and have wide application prospects in biomedicine, clinical diagnosis, environmental monitoring, and food safety.
Accompanied by unfavorable meteorological conditions with stable
stratification in various haze regions of China, persistent heavy aerosol
pollution episodes (HPEs) lasting more than 3 consecutive ...days frequently
occur, particularly in winter. In the North China Plain (NCP), explosive
growth of fine particulate matter smaller than 2.5 µm in
diameter (PM2.5), which occurs during some HPES, is dominated by
a two-way feedback mechanism between more unfavorable
meteorological conditions and cumulative aerosol pollution. However, the
existence of a two-way feedback mechanism such as this in other key haze regions in China is
uncertain; these regions include the Guanzhong Plain (GZP), the Yangtze River
Delta (YRD) region, the Two Lakes Basin (TLB; a large outflow basin connected to Hubei Province and Hunan Province), the Pearl River Delta (PRD)
region, the Sichuan Basin (SB), and the Northeast China Plain (NeCP). In this
study, using surface PM2.5 and radiation observations, radiosonde
observations, and reanalysis data, we observed the existence of a two-way
feedback mechanism in the six abovementioned regions. In the SB, this two-way feedback
mechanism is weak due to the suppression of cloudy mid-upper layers. In the
more polluted NCP, the GZP, and the NeCP, the feedback is more striking than
that in the YRD, the TLB, and the PRD. In these regions, the feedback of
worsened meteorological conditions on PM2.5 explains 60 %–70 % of
the increase in PM2.5 during the cumulative stages (CSs). For each
region, the low-level cooling bias becomes increasingly substantial with
increasing aerosol pollution and a closer distance to the ground surface.
With PM2.5 mass concentrations greater than 400 µg m−3,
the near-ground bias exceeded −4 ∘C in Beijing and reached up to
approximately −4 ∘C in Xi'an; this result was caused by
accumulated aerosol mass to some extent. In addition to the increase in
PM2.5 caused by the two-way feedback, these regions also suffer from the
regional transport of pollutants, including inter-regional transport in the
GZP, trans-regional transport from the NCP to the YRD and the TLB, and
southwesterly transport in the NeCP.
Electrooxidation of biomass into fine chemicals coupled with energy‐saving hydrogen production for a zero‐carbon economy holds great promise. Advanced anode catalysts determine the cell voltage and ...electrocatalytic efficiency greatly, further the rational design and optimization of their active site coordination remains a challenge. Herein, a phosphorus‐oxygen terminals‐rich species (Ni2P‐O‐300) via an anion‐assisted pyrolysis strategy is reported to induce strong electronic coupling and high valence state of active nickel sites over nickel phosphide. This ultimately facilitates the rapid yet in‐situ formation of high‐valence nickel with a high reaction activity under electrochemical conditions, and exhibits a low potential of 1.33 V vs. RHE at 10 mA cm−2, exceeding most of reported transition metal‐based catalysts. Advanced spectroscopy, theoretical calculations, and experiments reveal that the functional P‐O species can induce the favorable local bonding configurations for electronic coupling, promoting the electron transfer from Ni to P and the adsorption of benzyl alcohol (BA). Finally, the hydrogen production efficiency and kinetic constant of BA electrooxidation by Ni2P‐O‐300 are increased by 9‐ and 2.8‐ fold compared with the phosphorus‐oxygen terminals‐deficient catalysts (Ni2P‐O‐500). This provides an anion‐assisted pyrolysis strategy to modulate the electronic environment of the Ni site, enabling a guideline for Ni‐based energy/catalysis systems.
High‐valence nickel driven by phosphorus‐oxygen terminals‐rich species integrated on nickel foam substrate (Ni2P‐O‐300) is constructed by an anion‐assisted pyrolysis strategy, which promotes the rapid yet in situ formation of much high‐valence nickel with a high reaction activity at a relatively low potential under electrochemical conditions. Resultantly, the hydrogen production efficiency and kinetic constant of electrooxidation of benzyl alcohol driven by Ni2P‐O‐300 are 9‐ and 2.8‐ fold higher than that of Ni2P‐O‐500 with the deficient phosphorus‐oxygen terminals, respectively.
At present, the traditional ship traffic flow simulation technology has not been able to meet the requirements of researchers for model fidelity and simulation timeliness. Considering that AIS ...(Automatic Identification System) data has the characteristics of authenticity and real-time, ship traffic flow simulation based on these data can make the results more practical. For huge amounts of AIS data, it is difficult to solve problems by using the previous simulation methods. According to the achievements of machine learning method under the background of big data, the possibility of ship traffic flow simulation technology based on AIS data is analyzed.
Several statistics-based detectors, based on unimodal matrix models, for determining the number of sources in a field are designed. A new variance-ratio statistic is proposed, and its asymptotic ...distribution is analyzed. The variance-ratio detector is shown to outperform the alternatives. It is shown that further improvements are achievable via optimally selected rotations. Numerical experiments demonstrate the performance gains of our detection methods over the baseline approach.
Mining has caused considerable damage to vegetation coverage, especially in grasslands. It is of great significance to investigate the specific contributions of various factors to vegetation cover ...change. In this study, fractional vegetation coverage (FVC) is used as a proxy indicator for vegetation coverage. We constructed 50 sets of geographically weighted artificial neural network models for FVC and its driving factors in the Shengli Coalfield. Based on the idea of differentiation, we proposed the geographically weighted differential factors-artificial neural network (GWDF-ANN) to quantify the contributions of different driving factors on FVC changes in mining areas. The highlights of the study are as follows: (1) For the 50 models, the average RMSE was 0.052. The lowest RMSE was 0.007, and the highest was 0.112. For the MRE, the average value was 0.007, the lowest was 0.001, and the highest was 0.023. The GWDF-ANN model is suitable for quantifying FVC changes in mining areas. (2) Precipitation and temperature were the main driving factors for FVC change. The contributions were 32.45% for precipitation, 24.80% for temperature, 22.44% for mining, 14.44% for urban expansion, and 5.87% for topography. (3) Over time, the contributions of precipitation and temperature exhibited downward trends, while mining and urban expansion showed positive trajectories. For topography, its contribution remains generally unchanged. (4) As the distance from the mining area increases, the contribution of mining gradually decreases. At 200 m away, the contribution of mining was 26.69%; at 2000 m away, the value drops to 17.8%. (5) Mining has a cumulative effect on vegetation coverage both interannually and spatially. This study provides important support for understanding the mechanism of vegetation coverage change in mining areas.
Microfluidic impedance cytometry (MIC) has emerged as a popular technique for single-cell analysis. Traditional MIC electrode designs consist of a pair of (or three) working electrodes, and their ...detection performance needs further improvements for microorganisms. In this study, we designed an 8-electrode MIC device in which the center pair was defined as the working electrode, and the connection status of bypass electrodes could be changed. This allowed us to compare the performance of layouts with no bypasses and those with floating or grounding electrodes by simulation and experiment. The results of detecting Φ 5 μm beads revealed that both the grounding and the floating electrode outperformed the no bypass electrode, and the grounding electrode demonstrated the best signal-to-noise ratio (SNR), coefficient of variation (CV), and detection sensitivity. Furthermore, the effects of different bypass grounding areas (numbers of grounding electrodes) were investigated. Finally, particles passing at high horizontal positions can be detected, and Φ 1 μm beads can be measured in a wide channel (150 μm) using a fully grounding electrode, with the sensitivity of bead volume detection reaching 0.00097%. This provides a general MIC electrode optimization technology for detecting smaller particles, even macromolecular proteins, viruses, and exosomes in the future.
Banana wilt caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is a devastating fungal disease. Biocontrol strategies hold immense potential for inhibiting the spread of Foc TR4. ...Here, 30 actinobacteria were isolated from soils and screened for their antagonistic activity against Foc TR4. Strain SCA4-21 T was selected due to its strongest antagonistic activity against Foc TR4. Strain SCA4-21 T also exhibited strong antagonistic activity against the other eight phytopathogenic fungi. The strain was identified as the genus Streptomyces according to its physiological, biochemical, and phenotypic characteristics. The phylogenetic trees of 16S rRNA sequences demonstrated that strain SCA4-21 T formed a subclade with S. iranensis HM 35 T and/or S. rapamycinicus NRRL B-5491 T with low bootstrap values. Considering that 16S rRNAs did not provide sufficient resolution for species-level identification, the whole genome of strain SCA4-21 T was sequenced. Multilocus sequence analysis (MLSA) based on five housekeeping gene alleles ( atpD , gyrB , recA , rpoB , and trpB ) revealed that strain SCA4-21 T clustered into S. hygroscopicus subsp. hygroscopicus NBRC 13472 T with 100% of bootstrap value. The analysis of the genome-based phylogeny also approved the results. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) were 91.26 and 44.30%, respectively, with values below the respective species level threshold of 95 and 70%. Hence, strain SCA 4–21 T represented a novel species within the genus Streptomyces , named Streptomyces luomodiensis sp. nov. The type strain is SCA4-21 T (=GDMCC4.340 T = JCM36555 T ). By the CAZymes analysis, 348 carbohydrate-active enzymes (CAZymes) were detected, including 15 chitinases and eight β-1,3-glucanases. The fermentation broth of strain SCA4-21 T , exhibiting strong antagonistic activity against Foc TR4, demonstrated high activities of chitinase and β-1,3-glucanase, which might be involved in antifungal activity. Our results showed an innovative potential biocontrol agent for managing plant fungal diseases, specifically banana fusarium wilt.
Glaser‐coupled synthesized 1,3‐diyne can participate in the generation of conjugated polymers and is now widely used in organic and polymer synthesis. Currently, the catalyst in coupling are mostly ...based on the complexation of noble metals with complex organic ligands, which inevitably increases the research cost and storage difficulty. However, polyoxometalates (POMs), with acidic and redox properties, can be used as an excellent inorganic ligands with low cost and easy storage. In this work, we have synthesized copper catalyst 1, (NH4)4CuMo6O18(OH)6 with polyoxometalates as inorganic ligands in a facile way and applied them in the coupling of alkynes to obtain (non)symmetrical conjugated 1,3‐diynes in high yields without bases, finally proposing a reasonable reaction path. In addition, the catalyst showed good tolerance to a variety of different groups, further demonstrating its excellent catalytic activity. It is worth mentioning that the catalyst maintained its good structure and activity after six cycles, demonstrating its promising potential for industrial applications. Thus, this paper provides a new strategy for the preparation of (un)symmetrical diynes using polyoxometalates of Cu as catalyst, and also demonstrates the potential of multi‐acid catalyst for organocatalytic applications.
Using (NH4)4CuMo6O18(OH)6 as the catalyst, accelerates the Glaser‐Hay coupling of alkynes under easy conditions with moderate‐to‐high yields. Both symmetric and asymmetric couplings can be achieved with high selectivity. In addition, the catalyst is non‐toxic, green, environment‐friendly, and it can be recycled for at least six times while maintaining the catalytic activity.
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