Sensitivity of Commercial Enzyme Inhibition Colorimetric Pesticide Residue Rapid Test Kit to a Variety of Pesticides

[Objectives]To fully understand the quality of commercial enzyme inhibition-colorimetric pesticide residue rapid detection kits,so that they can play a greater role in the detection and supervision of agricultural products.[Methods]The sensitivity of 28 kinds of pesticides was determined by using the commercially available enzyme inhibition colorimetric rapid detection kit with Hendu brand.[Results]There was a significant difference in the sensitivity of the kit to each pesticide,and the kit was more sensitive to dichlorvos among the 28 pesticides tested.The sensitivity to methyl isosalifos,dimethoate,isocarbophos,fenthion and phorate was poor,and the sensitivity to quinalphos was different between 3.0 and 2.5 mL.[Conclusions]The large difference of the sensitivity of the enzyme inhibition-colorimetric rapid detection kit for pesticide residues to different kits is a reason for the false positive and false negative test results of the kit,which needs to be considered by relevant personnel.

一流本科专业建设背景下突出应用特色的多元化实践课程体系建设

在新时期教育部推动一流本科专业建设项目的背景下,作为一所地方性应用型高校,郑州轻工业大学应用化学专业在国家一流专业建设过程中,依托综合实验课程、国家级实践教学基地、产学研合作以及大学生学科竞赛等单元,建设起独具应用特色的多元化创新创业实践平台和人才培养体系,为一流专业建设中强化学科分层次发展和重点建设,提升应用化学专业人才教育质量提供了一种可供借鉴的模式。

Green tea polyphenols protect spinal cord neurons against hydrogen peroxide-induced oxidative stress

Green tea polyphenols are strong antioxidants and can reduce free radical damage. To investigate their neuroprotective potential, we induced oxidative damage in spinal cord neurons using hydrogen peroxide, and applied different concentrations （50-200μg,/mL） of green tea polyphenol to the cell medium for 24 hours. Measurements of superoxide dismutase activity, malondialdehyde content, and expression of apoptosis-related genes and proteins revealed that green tea polyphenol effectively alleviated oxidative stress. Our results indicate that green tea polyphenols play a protective role in spinal cord neurons under oxidative stress.

Simulation and Experimental Study on the Atomization Character of the Pressure-Swirl Nozzle

In this paper the atomization character of the pressure-swirl injector was measured by using the Phase Doppler Particle Analyzer (PDPA) in the section of 150 mm below the outlet of the orifice. The orifice diameter of the pressure-swirl injector is 0.62 mm. The atomization character includes the spray angle, the water flow rate, the Sauter mean diameter (SMD), the velocity of the particles and their distribution in the radial and the axial directions under the pressure from 1 MPa to 4.5 MPa. After that the atomization character of the pressure-swirl injector was simulated in the DPM panel. The same atomization character of the injector was calculated and compared with the experimental data. The simulation was corrected by using the experimental data which can make it accurately and the model can be used to predict and calculate the atomization character of different injectors.

Analysis of Pesticide Residues in Vegetables by Enzyme Inhibition Colorimetric Kit

[Objectives]The paper was to understand the detection effect of commercial enzyme inhibition colorimetric kit.[Methods]Six brands of kits were used to detect pesticide residues in vegetables.The detection results were compared with those of 50 kinds of organophosphorus pesticides and 10 kinds of carbamate pesticides detected by chromatography and mass spectrometry.According to different thresholds,the test results of different kits were evaluated,and the false positive rate,false negative rate and coincidence rate of each kit were obtained.The test results of commercial enzyme inhibition colorimetric kits were compared and analyzed.[Results]The detection effect of kit D was the best among the 6 brands of kits,and the coincidence rate was the highest under the 7 thresholds.There was a certain relationship between the detection effect of commercial enzyme inhibition colorimetric kit and the determination threshold of positive samples.The false positive rate decreased with the increase of determination threshold,and the false negative rate increased with the increase of determination threshold,but the coincidence rate with chromatography and mass spectrometry can not reach 100%.When the threshold was set to 20%,the effect was the best.The coincidence rate of 3 brands of kits with the results of chromatography and mass spectrometry was the highest,and none of the 6 kits involved in the comparison had the lowest coincidence rate under this threshold.[Conclusions]It is suggested to modify the threshold values in national standard and trade standard.

One-year status of hepatic venous pressure gradient measurement from 85 hospitals in China

Aims:Surveys and research on the applications of the hepatic venous pressure gradient(HVPG)are important for understanding the current status and future development of this technology in China.This article aimed to investigate the status of hepatic venous pressure gradient measurement in China in 2022.Methods:We investigated the overall status of HVPG technology in China-including hospital distribution,hospital level,annual number of cases,catheters used,average cost,indications,and current challenges by using online questionnaire.By counting the number and percentages of cases of these results,we hope to clarify the current status of HVPG measurements in China.Results:According to the survey,85 hospitals in China used HVPG technology in 2022 distributed across 29 provinces.A total of 4989 HVPG measurements were performed in all of the surveyed hospitals in 2022,of which 2813 cases(56.4%)were measured alone.The average cost of HVPG measurement was 5646.8±2327.9 CNY.Of the clinical teams who performed the measurements(sometimes multiple per hospital),94.3%(82/87)used the balloon method,and the majority of the teams(72.4%,63/87)used embolectomy catheters.Conclusions:This survey clarified the clinical application status of HVPG in China and confirmed that some medical institutions in China have established a foundation for this technology.It is still necessary to continue promoting and popularizing this technology in the future.

Status of transjugular intrahepatic portosystemic shunt for portal hypertension in China:A national survey analysis

Aim:The transjugular intrahepatic portosystemic shunt(TIPS)procedure has been performed in China for 30 years,but our understanding of the status and difficulties associated with the use of TIPS for portal hypertension is incomplete.This study aims to investigate the current situation of the use of TIPS for portal hypertension,which should aid the development of TIPS in China.Methods:This study involved a questionnaire survey,initiated by the China Portal Hypertension Alliance(CHESS)to investigate the use of TIPS for portal hypertension in China.Questionnaires were released on the Internet between August 16,2022 and September 16,2022.Detailed information was collected from 545 hospitals contracted by the CHESS in China,which performed TIPS surgery in 2021.Results:The 545 hospitals covers the majority of hospitals in China that conduct TIPS intervention.In the survey,a total of 13,527 TIPS interventions were carried out with 94.1%(498/545)of them had a system of routine follow‐up after TIPS.The majority(42.6%[232/545])believed that the main indication of TIPS was the control of acute bleeding.Overall,48.1%(262/545)carried out early or pre‐emptive TIPS,53.0%(289/545)carried out TIPS for cavernous transformation of the portal vein,and 81.0%(441/545)chose routine embolization of collateral circulation during operation.Most used coils(97.0%[475/490])and biological glue(72.0%[353/490])as embolic materials,and 78.5%(428/545)routinely performed intraoperative portal pressure gradient measurements.When selecting TIPS stents,57.1%(311/545)chose viator‐specific stents,and 57.2%(312/545)chose conventional anticoagulation after TIPS.Conventional anticoagulation after TIPS is over a time interval of 3–6 months(55.4%[173/312]).The limitation of TIPS surgery is mainly its cost(72.3%[394/545])and insufficient understanding of the procedure by doctors in other related departments(77.4%[422/545]).Most of the hospital teams accept the use of domestic instruments in TIPS surgery(92.7%[505/545]).Conclusions:This survey shows that TIPS is an essential part of the treatment of portal hypertension in China.TIPS is widely used in Chinese patients with portal hypertension,and this survey presents a more comprehensive picture of the options and difficulties encountered in the implementation of TIPS.In the future,it is necessary to promote TIPS technology and further standardize surgical indications,routine operations,and instrument application.

Physics package based on intracavity laser cooling ^(87)Rb atoms for space cold atom microwave clock

This article proposes a new physics package to enhance the frequency stability of the space cold atom clock with the advantages of a microgravity environment. Clock working processes, including atom cooling, atomic state preparation,microwave interrogation, and transition probability detection, are integrated into the cylindrical microwave cavity to achieve a high-performance and compact physics package for the space cold atom clock. We present the detailed design and ground-test results of the cold atom clock physics package in this article, which demonstrates a frequency stability of 1.2×10^(-􀀀12) τ^(-1/2) with a Ramsey linewidth of 12.5 Hz, and a better performance is predicted with a 1 Hz or a narrower Ramsey linewidth in microgravity environment. The miniaturized cold atom clock based on intracavity cooling has great potential for achieving space high-precision time-frequency reference in the future.

Integrated cooperative guidance framework and cooperative guidance law for multi-missile

An integrated cooperative guidance framework for multi-missile cooperatively attacking a single stationary target is proposed in this paper by combining both the centralized and decentralized communication topologies. Once missiles are distributed into several groups, missiles within a single group communicate with the centralized leader-follower framework, while the leaders from different groups communicate using the nearest-neighbor topology. To implement the integrated cooperative guidance framework, a group of Finite-Time Cooperative Guidance（FTCG） laws considering the saturation constraint on FOV（FTCG-FOV） are firstly derived within the centralized leader-follower framework to satisfy the communication topology of missiles in a single group.Then, an improved sequential approach is developed to adapt the FTCG-FOV to satisfy the communication topology between groups. The numerical simulations demonstrate the effectiveness and high efficiency of the integrated cooperative guidance framework and the cooperative guidance laws, as well as the superiority of the developed sequential approach.

Cooperative guidance of seeker-less missile considering localization error

To perform an accurate fire-and-forget attack of seeker-less missile with the consideration of the localization error, a new cooperative guidance strategy of multi-missiles is proposed in this work. Firstly, an estimated position of the seeker-less missile is carefully selected, based on which the slant angle of the line between the estimated and real positions of the seeker-less missile is approximately derived inspired by the localization theory of GPS(Global Position System).Then, respectively based on the guidance law considering the impact angle and time constraints, the consensus theory and the finite-time convergence approach, three cooperative guidance laws employing the previously obtained slant angle are derived for intensive attack to address either a stationary or maneuvering target. Simulation results well demonstrate the effectiveness and advantages of the proposed cooperative guidance strategy.

Experiment and Prediction of Fire Extinguishment with Water Mist in an Enclosed Room

The correlation between oxygen concentration and fire temperature when fire was extinguished with water mist was theoretically studied. The Semenov theory was applied to analyze the critical condition when fire was extinguished with water mist, from which the correlation could be obtained. The water mist experiments were carried out by varying the fire size, atomizer number, ceiling height, system pressure, and pre-burn time in an enclosed room. The oxygen concentration near the edge of the liquid pool and the fire temperature above the center of the liquid pool were measured. A comparison of the experimental data with the correlation was made under different conditions. The results showed that fire extinguishment was a stochastic process which could be affected by many factors. This theoretical model could predict the correlation between fire temperature and oxygen concentration when fire was extinguished with water mist in an enclosed room and it can also be treated as a critical condition for fire extinguishment.

Calculation of fire extinguishment time with water mist in an enclosed room

The fire extinguishment time is a major factor to evaluate the efficiency of fire extinguishment with water mist. In this paper the fire extinguishment time with water mist in an enclosed room is calculated. Before adding water mist, the chemical kinetics plays the role in combustion, where a dimensionless math model is established by us-ing the Semenov theory. After adding water mist, the diffusion plays the role instead. Then another math model containing water mist and dominated by oxygen concentration is established. The fire temperature is integrated from Tm to extinguishment temperature TB and the extinguishment time can be obtained. The calculated values are compared with the experimental data under different conditions. The results show that this model can predict the fire extinguishment time accurately. Besides, this model also can be used to determine the critical water mist flux and evaluate which fire extinguishment mechanisms dominate the extinguishment.

Synthesis of micro/meso porous carbon for ultrahigh hydrogen adsorption using cross-linked polyaspartic acid

In addition to the specific surface area,surface topography and characteristics such as the pore size,pore size distribution,and micro/mesopores ratio are factors that determine the performance of porous carbons(PCs)in the fields of energy,catalysis,and adsorption.Based on the mechanism of weight loss of polyaspartic acid at high temperatures,this study provided a new method for adjusting the surface morphology of PCs by changing the cross-linking ratio of the precursor,where cross-linked polyaspartic acid was used as precursor without additional activating agents.N2 adsorption analysis indicated that the specific surface area of the obtained PCs was as high as 1458 m2·g-1,of which I 200 m2·g-1was the contribution of the microporous area and the highest pore volume was 1.13 cm3·g-1,of which the micropore volume was 0.636cm3·g-1.The thermogravimetric analysis results of the precursor,and also the scanning electron microscopy and Brunauer-Emmet-Teller analysis results of the carboniza-tion product confirmed that the prepared PCs presented multilevel pore structure,and the diameters of most pores were 0.78 and 3.97 nm;moreover,the pore size distribution was relatively uniform.This conferred the PCs the ultrahigh hydrogen adsorption capacity of up to 4.52 wt-%at 77 K and 1.13 bar,in addition to their great energy storage and catalytic potental.

Optimization of temperature characteristics of a transportable 87Rb atomic fountain clock

A high-performance transportable fountain clockis attractive for use in laboratories with high-precisiontime-frequency measurement requirements. This Letterreports the improvement of the stability of atransportable rubidium-87 fountain clock because of anoptimization of temperature characteristics. This clockintegrates its physical packaging, optical benches,microwave frequency synthesizers, and electronic controlsonto an easily movable wheeled plate. Two optical bencheswith a high-vibration resistance are realized in thiswork. No additional adjustment is required after movingthem several times. The Allan deviation of the fountainclock frequency was measured by comparing it with that ofthe hydrogen maser. The fountain clock got a short-termstability of 2.3×10^-13 at 1 s and long-term stabilityon the order of 10-16 at 100,000 s.

AuPt bimetallic nanoalloys supported on SBA-15:A superior catalyst for quinoline selective hydrogenation in water

The structure and size of bimetallic catalysts play a crucial role in many important chemical transformations.Controlled synthesis of bimetallic nanoparticles avoiding overgrowth and aggregation can be achieved by surfactants,which are always detrimental to catalytic performances and understanding of structure-property relationship.Preparation of surface-clean bimetallic catalysts with uniform size and well-defined structure is still challenging.Herein the Au-Pt bimetallic nanoparticles immobilized on SBA-15 were prepared by facile adsorption-reduction method.Characterizations showed that Au-Pt bimetallic nanoparticles were evenly confined within the mesopores of SBA-15,possessing the uniform size of 6.0 nm and existing in the form of alloy structure.For the first time the Au-Pt bimetallic nanoalloys with Au-to-Pt molar ratio of 5:1(Au5Pt1@SBA-15)exhibited a lot higher activity than monometallic Au@SBA-15 and Pt@SBA-15 catalysts with excellent selectivity towards 1,2,3,4-tetrahydroquinoline for chemoselective hydrogenation of quinoline in water under very mild conditions.It was superior to other heterogeneous catalysts reported to date.The observed properties were related to the synergic effect between Au and Pt.The Pt sites of high electron density originated from the electron transfer between Au and Pt enhanced the ability of H_(2) dissociation and then provided a new and main approach to H_(2) splitting,while the Au sites accounted for the adsorption and activation of quinoline.This precise synthetic strategy will be very helpful to explore surface-clean gold-based bimetallic catalysts with high performance for selective hydrogenations.