Lonicera japonica Thunb. leaves were used to biosynthesize silver nanoparticles (AgNPs), while its antibacterial and antifungal properties were investigated. Reaction conditions of AgNPs which characterized were optimized. The maximum absorption wavelength of the AgNPs was located about 400 nm, with a spherical shape and a particle size of 14.87±4.07 nm. Produced AgNPs showed effective antibacterial activities against tested bacterial strains. Minimal inhibitory concentrations and minimum bactericidal concentrations of the AgNPs were 0.25 and 0.5 mg/mL for Escherichia coli (E. coli), and 0.5 and 1.0 mg/mL for Staphylococcus aureus, respectively. According to the mechanism study, AgNPs generated morphological changes in E. coli and disrupted membrane integrity. Furthermore, AgNPs which showed effective dose-dependent inhibitory effects against Penicillium citrinum could suppress the growth of fungal mycelium on citrus peels. Conclusively, AgNPs generated by this facile and green method showed effective antimicrobial activity, which is promising in food processing and preservation.
The cavitation flow of the cartridge pilot-operated relief valve's main valve port was numerically simulated and studied using Computational Fluid Dynamics (CFD) in our research, and the relief valve structure was modified to decrease cavitation noise. The findings indicate that cavitation in the relief valve occurs mostly downstream of the main valve port and is linked to the wall. Cavitation generation is influenced by the jet at the valve port. The closer the high-speed jet at the valve port is to the valve's inner wall, the more readily cavitation occurs. Conversely, there is less cavitation. This paper reports the effect of the forms and parameters of the main port structure on the jet angle and the morphology of cavitation. The structure of the spool's annular groove has a considerable influence on the cavitation attached to the spool wall and the valve sleeve wall, whereas the outlet position of the relief valve mostly impacts the intensity of cavitation near the valve sleeve wall. Based on this, the relief valve's optimized structure is designed, with which the maximum vapor volume fraction and total vapor volume of the cavitation flow are considerably decreased for various inlet pressures and spool openings. The results of the experiment show that following optimization, the noise of the relief valve drops dramatically, confirming that optimizing the structure has a beneficial impact on decreasing cavitation noise.
An efficient glutamate oxidase (GluOx) amperometric biosensor for sensitively detecting L-glutamic acid (Glu) in agricultural and biological samples using an integrated biocompatible poly(3,4- ethylenedioxythiophene) (PEDOT) nanocomposite bioelectrode was facilely fabricated by the one-step electrochemical deposition technique in ionic liquid-in-water microemulsion containing multi-walled carbon nanotubes, GluOx, 3,4-ethylenedioxythiophene, 1-ethyl-3-methylimidazolium ethyl sulfate, sodium N-lauroylsarcosinate and LiClO4. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that the as-prepared PEDOT nanocomposite bioelectrode exhibited better electron-transfer ability than individual component, and GluOx were successfully immobilized into this bioelectrode. The sensing parameters such as working potentials, pH values, and temperature and performance like sensitivity, response time, limit of detection (LOD), stability, specificity and applicability of the as-fabricated bioelectrode were assessed. This biosensor demonstrated good bioelectrocatalytic response towards Glu in a linear range from 0.6 μM to 2 mM with a pronounced sensitivity of 10.12 μA mM-1 cm-2, short response time within 5-10 s, low LOD of 0.27 μM, high stability, good selectivity and satisfactory practicality. All these indicate that the proposed GluOx biosensor will provide a promising platform for determining Glu in agricultural and biological samples.
Electrochemical sensor has great potential in the detection of small molecules by virtues of low cost, fast response, and easy to miniaturization. However, electrochemical sensing of ochratoxin A (OTA) was seriously hindered by the heavy electrode-fouling effect and poor electrochemical activity inherent from OTA molecular. Herein, two-dimensional titanium carbide (2D Ti3C2) MXene incorporated with carboxylic multiwalled carbon nanotubes (cMWCNTs) was developed as a glassy carbon electrode modifier for rapid and sensitive detection of OTA. Physical characterizations combined with electrochemical techniques revealed that cMWCNTs can not only prevent the restacking of 2D Ti3C2nanosheets but also facile its electron transfer, leading to a nanohybrid with a high specific surface and good electrocatalytic activity to OTA. Under optimal conditions, the electrochemical sensor showed a good linear response to OTA in a concentration range from 0.09 to 10μmol·l-1and a low detection limit (LOD) of 0.028μmol·l-1. The proposed sensor was impelled successive times to detect OTA, a good repeatability was obtained, indicating the constructed sensor possessed good anti-fouling property. Moreover, satisfactory recoveries between 91.8% and 103.2% were obtained in the real sample analysis of grape and beer, showing that the developed sensing technique is reliable for the screening of trace OTA in food resources.
A new pre-separation extraction method and a new separation process for the rare earth mineral with middle Y and rich Eu were introduced.The first step of the new process is a pre-separation extraction process of three outlet with number of stages more 10,the raffinate La~Gd(TbDy) directly flows into separation process of Nd/Sm.The(Gd)Tb~HoY(Er) of middle outlet is used as aqueous feed of Gd~Dy/Ho ~LuY process,the extract loaded(Ho)Er~LuY directly flows into the scrubbing section of the Gd~Dy/Ho ~LuY process.As a result,the pre-separation extraction process of the new process separates out the La~Gd(TbDy),and the content in raw material is approximately 70% from raw material,the feed flowing into Gd~Dy/Ho~ LuY process decreases(approximately) 70%.Due to the Ho_2O_3 content in the raffinate of the Gd~Dy/Ho~LuY process less than 0.03%,the separation GdTbDy/ HoY of the GdTbDy(HoY) concentrate from original process is leaved out. While the process handling capacity with the new process increases more 30%,the consumption of chemical reagents including HCl and NH_3 decreases 20%,the hold capacity of valuable rare earth element Eu and Tb reduces largely.
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