Effective disinfection of contaminated surfaces is essential for preventing the transmission of pathogens. In this study, we investigated the UV irradiance and wavelength distribution of a 222-nm ultraviolet C (UVC) excimer lamp and its disinfection efficacy against microorganisms in laboratory conditions. By using a carrier quantitative germicidal test with stainless steel sheets as carriers, we examined the disinfection effect of the 222-nm UVC lamp on three standard strains-Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. We tested the disinfection efficacy under different conditions by adjusting irradiation time, as well as the state and temperature of the stainless steel carriers. Our results indicated that a bacterial suspension in PBS and not-dried stainless steel carriers yielded better disinfection than in TSB and dried carriers. Additionally, carrier temperature had no significant impact on disinfection efficacy. When utilizing a bacterial suspension in PBS and non-dried carriers at a temperature of 20 °C, the three bacteria were eliminated by 222-nm UVC excimer lamp irradiation in just 15 s. In contrast, when using a bacterial suspension in TSB and dried carriers at temperatures of 20 °C, 4 °C, or − 20 °C, the three bacteria were eradicated by 222-nm UVC excimer lamp irradiation in 60 s. Comparatively, the LPM lamp required more than 10 min to achieve the same disinfection effect. Our data demonstrate that the 222-nm UVC excimer lamp has higher irradiance and a more potent microbial disinfection effect than the LPM lamp, requiring significantly less irradiation time to achieve the same disinfection effect under identical conditions. Furthermore, the 222-nm UVC excimer lamp exhibited a substantial disinfection effect on bacterial propagules at low temperatures. Our findings support the optimization of “tunnel-type” cold-chain goods disinfection devices, providing an alternative, highly efficient, and practical tool to combat the spread of SARS-CoV-2 through cold-chain systems.
A method was established for determining chlorine content in imported coal by high temperature combustion hydrolysis-automatic potentiometric titration. Automatic potential titration instrument conditions, acidity effect, titration mode,minimum addition of titration agent, identification and determination of titration endpoints were studied to obtain the best conditions for automatic potential titration. With this method to determine the chlorine in standard coal samples, the accuracy and precision are comparable to the national standard method. After the chlorine content in 4 levels coal samples was determined by eight laboratories,the data were tested by Grubbs and Cochran tests. The data agreed well with the standard value of the standard samples, and then the formulas for calculating the repeatability limit and reproducibility limit of the method were presented. The results showed that the method had the advantages of high automatization, simple operation, high accuracy and good reproducibility.
为提高检验人员正确运用有效数字修约及运算规则的技能水平,提高检测结果准确性,本文依据标准GB/T 8170-2008《数值修约规则与极限数值的表示与判定》中的数值修约规则,举例说明数值修约在矿产品检测中的广泛应用.通过详细案例分析说明数值修约对检测结果及人力、物力、财力等经济利益所产生的重要影响.检验人员在检测中应正确掌握数值修约规则,保证并提高检测结果准确性,使出具的检测结果准确、科学、公正、有效,对提高检测结果的准确性具有重要意义.
The uncertainty evaluation method was discussed for the determination of the arsenic content in copper concentrate by inductively coupled plasma emission spectroscopy（ICP-OES）. The source of uncertainty in the whole determination process was analyzed, including measured volume, standard weighting, repeatability tests. The repetitive measurement correction factor was introduced into the mathematical model to simplify the uncertainty calculation process. Through derivation and calculation,the expanded uncertainty of arsenic content in copper concentrate was given, and the main sources affecting the uncertainty of measurement results were analyzed, which provided a reference model for the evaluation method of measurement uncertainty by ICP-OES method.
本文研究并建立了波长色散型X射线荧光光谱法快速测定塑料制品中铅、镉含量的分析方法.采用塑料类高含量标准物质ERM-EC681k和低含量ERM-EC680k作为研究对象,考察了低温熔融法和粉碎压片法制备样品对测试结果的影响.实验结果表明,低温熔融法相对标准偏差小于2.3%,粉碎压片法相对标准偏差小于1.8%,两种制备样品方法均满足测试要求,将两种制备样品方法同微波消解-电感耦合等离子体原子发射光谱法进行比较,塑料样品中铅、镉测试结果基本一致,不存在显著性差异.本研究的思路为测定塑料中其他重金属含量提供了较好的借鉴意义.
