[The influence of meteorological factors on SARS-CoV-2 transmission: evidence from laboratory and epidemiological studies]

SARS-CoV-2 has infected more than 600 million people worldwide and caused more than 6 million deaths. The emerging novel variants have made the epidemic rebound in many places. Meteorological factors can affect the epidemic spread by changing virus activity, transmission dynamic parameters and host susceptibility. This paper systematically analyzed the currently available laboratory and epidemiological studies on the association between the meteorological factors and COVID-19 incidence, in order to provide scientific evidence for future epidemic control and prevention, as well as developing early warning system.

Fabrication of Nano/Micro-Structured Electrospun Detection Card for the Detection of Pesticide Residues

A novel nano/micro-structured pesticide detection card was developed by combining electrospinning and hydrophilic modification, and its feasibility for detecting different pesticides was investigated. Here, the plain and hydrophilic-modified poly(ε-caprolactone) (PCL) fiber mats were used for the absorption of indolyl acetate and acetylcholinesterase (AChE), respectively. By pre-treating the fiber mat with ethanol, its surface wettability was improved, thus, promoting the hydrolysis of the PCL fiber mat. Furthermore, the absorption efficiency of AChE was improved by almost two times due to the increased hydrophilicity of the modified fiber mat. Noteworthily, this self-made detection card showed a 5-fold, 2-fold, and 1.5-fold reduction of the minimum detectable concentration for carbofuran, malathion, and trichlorfon, respectively, compared to the national standard values. Additionally, it also exhibited good stability when stored at 4 °C and room temperature. The food detection test showed that this nano/micro-based detection card had better detectability than the commercial detection card. Therefore, this study offers new insights into the design of pesticide detection cards, which also broadens the application of electrospinning technique.

Development of a novel nano-based detection card by electrospinning for rapid and sensitive analysis of pesticide residues

BACKGROUND

Increasing food safety awareness of consumers promotes the development of rapid and sensitive detection techniques for pesticide residues. In this study, a new type of rapid detection card for organophosphorus and carbamate pesticide residues was developed by electrospinning. The card involved enzyme fiber mat (EFM) and substrate fiber mat (SFM) which were prepared by mixing poly(vinyl alcohol) with acetylcholinesterase (AChE) and indolyl acetate (IA), respectively.

RESULTS

The mean diameter of fibers was 240 ± 53 nm for EFM and 387 ± 84 nm for SFM. Results of Fourier transform infrared and X-ray photoelectron spectroscopies confirmed that AChE and IA were successfully encapsulated into the fibers. The minimum concentrations of AChE and IA for effective detection were 1 and 3 mg mL^-1 , respectively, and the optimal detection time was 15 min. The limits of detection for this card were 0.5 mg L^-1 for omethoate, 1.5 mg L^-1 for malathion, 0.1 mg L^-1 for carbaryl and 0.02 mg L^-1 for carbofuran. The detection card exhibited good storage stability and its activity could be maintained when stored at room temperature for at least 4 months. Additionally, the EFM can be reused three times.

CONCLUSIONS

The detection card obtained here was superior to a commercial card in detecting pesticide residues in real food samples. Hence, this electrospun detection card has potential for simple, rapid and sensitive analysis of pesticide residues. © 2020 Society of Chemical Industry.

Improved Viability and Thermal Stability of the Probiotics Encapsulated in a Novel Electrospun Fiber Mat

For the enhancement of the probiotics' survivability, a nanostructured fiber mat was developed by electrospinning. The probiotic Lactobacillus plantarum was encapsulated in the nanofibers with fructooligosaccharides (FOS) as the cell material. Fluorescence microscope image and scanning electron microscopy (SEM) showed that viable cells were successfully encapsulated in nanofibers (mean diameter = 410 ± 150 nm), and the applied voltage had no significant influence on their viability ( P > 0.05). A significantly improved viability (1.1 log) was achieved by incorporating 2.5% (w/w) of FOS as the electrospinning material ( P < 0.001). Additionally, compared with free cells, the survivability of cells encapsulated in electrospun FOS/PVA/ L. plantarum nanofibers was significantly enhanced under moist heat treatment (60 and 70 °C). This study shows that the obtained nanofiber is a feasible entrapment structure to improve the viability and thermal stability of encapsulated probiotic cells and provides an alternative approach for the development of functional food.