西安建筑科技大学学报(自然科学版)

建筑室内表面常见含不同微生物的液滴.已有研究往往将微生物液滴过度简化为纯水或盐溶液液滴,以体现环境湿度和组分中吸湿性盐离子等化学组分对蒸发速率的影响.本研究选择了通过测量浓度为107 CFU/ml的3种室内环境中的常见细菌所在液滴在室内常见表面上蒸发时的质量及接触角的变化,系统研究了细菌属种对液滴蒸发率、接触角等参数的量化影响.测量发现,同等条件下,在0.9%(w/v)氯化钠溶液液滴中加入不同微生物后,类干酪乳杆菌和大肠埃希氏杆菌可以降低蒸发率,延长蒸发时间约50%～60%; 枯草芽孢杆菌提高蒸发率,缩短蒸发时间约20%.实验结果表明芽孢能够显著提高液滴的液面张力; 微生物的存在使液滴在空气中的悬浮时间变长,预示着更大的空气扩散危险及室内环境的污染.

Indoor microbial environment essentially characterizes the human exposure to potential pathogens. Many microorganisms are emitted within droplets. Previous studies often oversimplify these droplets as droplets of pure water or NaCl solution.The impact of the microbial components on droplet evaporation is not clear. In this study, we chose three common bacteria in indoor environment. They were suspended in 0.9%(w/v)NaCl solutions with an initial concentration of 107 CFU/ml. We then measured the mass loss and contact angle variation of these droplets on a polyethylene surface that represents the common indoor surfaces with hydrophobic paint.Results reveal that Lactobacillus casei and Escherichia coli can slow down droplet evaporation, and the total evaporation time can be prolonged by about 50%～60%. Bacillus subtilis can accelerate the evaporation and shorten the evaporation time by about 20%; The presence of microorganisms makes the suspension time of the droplets in the air longer, indicating a greater risk of dispersion and contamination of the indoor environment.

引言
1 实验材料与方法
2 实验结果与讨论
3 结论

表1 建筑室内常见表面材料的接触角范围表<br/>Tab.1 Contact angle range of common surface materials in building interior

表1 建筑室内常见表面材料的接触角范围表
Tab.1 Contact angle range of common surface materials in building interior

图1 实验系统示意图<br/>Fig.1 Schematic diagram of the experimental system

图1 实验系统示意图
Fig.1 Schematic diagram of the experimental system

图2 纯水待测液滴蒸发过程图<br/>Fig.2 Evaporation process of pure water droplets to be tested

图2 纯水待测液滴蒸发过程图
Fig.2 Evaporation process of pure water droplets to be tested

图3 纯水与已有结果对比:质量变化<br/>Fig.3 Comparison of pure water droplet evaporation with existing studies: mass loss by time

图3 纯水与已有结果对比:质量变化
Fig.3 Comparison of pure water droplet evaporation with existing studies: mass loss by time

图4 纯水与已有结果对比:接触角变化<br/>Fig.4 Comparison of pure water droplet evaporation with existing studies: variation of contact angle by time

图4 纯水与已有结果对比:接触角变化
Fig.4 Comparison of pure water droplet evaporation with existing studies: variation of contact angle by time

图5 生理盐水液滴质量蒸发率及接触角改变率随时间变化图<br/>Fig.5 Variation of mass evaporation rate and contact angle change rate of NaCl solution

图5 生理盐水液滴质量蒸发率及接触角改变率随时间变化图
Fig.5 Variation of mass evaporation rate and contact angle change rate of NaCl solution

表2 5种不同液滴蒸发信息汇总表<br/>Tab.2 Evaporation status of 5 different droplets

表2 5种不同液滴蒸发信息汇总表
Tab.2 Evaporation status of 5 different droplets

图6 对比生理盐水不同细菌液滴蒸发特性:蒸发率<br/>Fig.6 Evaporation characteristics of bacterial droplets:mass loss

图6 对比生理盐水不同细菌液滴蒸发特性:蒸发率
Fig.6 Evaporation characteristics of bacterial droplets:mass loss

图7 对比生理盐水不同细菌液滴蒸发特性:接触角变化率<br/>Fig.7 Evaporation characteristics of bacterial droplets:contact angle

图7 对比生理盐水不同细菌液滴蒸发特性:接触角变化率
Fig.7 Evaporation characteristics of bacterial droplets:contact angle

图8 对比生理盐水不同细菌液滴蒸发特性:高度和接触直径<br/>Fig.8 Evaporation characteristics of bacterial droplets:diameter and height

图8 对比生理盐水不同细菌液滴蒸发特性:高度和接触直径
Fig.8 Evaporation characteristics of bacterial droplets:diameter and height

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备注

引言

1 实验材料与方法

2 实验结果与讨论

3 结论

期刊信息