大气细菌粒子浓度的时间分布特征及最佳采样时间的研究

用ＭＦ－４５型和ＨＴＫ－２０１型空气微生物采样器分别在北京、天津和沈阳三地观测了不同季节和一天中大气细菌粒子的浓度及其变化。结果表明：京、津二地春季大气细菌粒子浓度高，分别为２０５３个／ｍ３和２５５６个／ｍ３；夏季低，分别为９９５个／ｍ３和１０６４个／ｍ３。沈阳秋季大气细菌粒子浓度高，为１０１０８个／ｍ３；冬季低，为１２９４个／ｍ３。一天中，大气细菌粒子浓度呈双峰型变化，６：００～７：００和１８：００时大气细菌粒子浓度高，１１：００～１３：００和１：００～２：００时大气细菌粒子浓度低。根据大气细菌粒子浓度的季节变化和一天中大气细菌粒子浓度的时间分布特征，经过京、津、沈三地一天中分别１２次、８次、６次和４次不同采样时间组合的大气细菌粒子浓度的数理统计分析，大气细菌粒子浓度的监测拟集中在一年冬、春、夏、秋四季的中间月份，即１月、４月、７月、１０月进行；一天中采样８次的时间序列可为７：００、１０：００、１３：００、１６：００、１９：００、２２：００、１：００、４：００一天采样４次的时间序列可为５：００、１１：００、１７：００、２３：００。白天采样４次的时间序列可为春、秋季６：００、９：００、１２：００、１５：００?     

The effect of respiratory activity,non-invasive respiratory support and facemasks on aerosol generation and its relevance to COVID-19

Respirable aerosols (< 5 µm in diameter) present a high risk of SARS-CoV-2 transmission. Guidelines recommend using aerosol precautions during aerosol-generating procedures, and droplet (> 5 µm) precautions at other times. However, emerging evidence indicates respiratory activities may be a more important source of aerosols than clinical procedures such as tracheal intubation. We aimed to measure the size, total number and volume of all human aerosols exhaled during respiratory activities and therapies. We used a novel chamber with an optical particle counter sampling at 100 l.min^-1 to count and size-fractionate close to all exhaled particles (0.5–25 µm). We compared emissions from ten healthy subjects during six respiratory activities (quiet breathing; talking; shouting; forced expiratory manoeuvres; exercise; and coughing) with three respiratory therapies (high-flow nasal oxygen and single or dual circuit non-invasive positive pressure ventilation). Activities were repeated while wearing facemasks. When compared with quiet breathing, exertional respiratory activities increased particle counts 34.6-fold during talking and 370.8-fold during coughing (p < 0.001). High-flow nasal oxygen 60 at l.min^-1 increased particle counts 2.3-fold (p = 0.031) during quiet breathing. Single and dual circuit non-invasive respiratory therapy at 25/10 cm.H₂O with quiet breathing increased counts by 2.6-fold and 7.8-fold, respectively (both p < 0.001). During exertional activities, respiratory therapies and facemasks reduced emissions compared with activities alone. Respiratory activities (including exertional breathing and coughing) which mimic respiratory patterns during illness generate substantially more aerosols than non-invasive respiratory therapies, which conversely can reduce total emissions. We argue the risk of aerosol exposure is underappreciated and warrants widespread, targeted interventions.     

常见大气细菌对动物肺损伤的实验研究

为研究大气微生物对人体健康的影响,于１９９７年对上海市大气细菌污染进行了调查。在此基础上,采用大鼠经气管灌注细菌悬液２４小时后,分析肺灌洗液组成的方法,就大气细菌对动物呼吸系统损伤方面进行了研究。同时比较了不同地区大气细菌对大鼠肺细胞的损伤效应。结果发现大气细菌污染严重地区的细菌染毒组ＡＬＢ、ＬＤＨ、ＡＣＰ、ＡＫＰ、中性粒细胞等指标比清洁区升高更为显著,提示大气中常见细菌可对肺组织造成损伤。     

Comparing yield estimates derived from LiDAR and aerial photogrammetric point-cloud data with cut-to-length harvester data in a Pinus radiata plantation in Tasmania

Accurate mapping of timber resources in commercial forestry is essential to support planning and management operations of forest growers. Over the last two decades, Light Detection and Ranging (LiDAR) systems have been successfully deployed for the collection of point-cloud data for accurate modelling of forest attributes that are traditionally obtained from plot-based inventory. In recent years, studies conducted in North America and Scandinavia have shown that three-dimensional point clouds derived from digital aerial photogrammetric (AP) data can be used to model forest attributes with a level of accuracy similar to traditional LiDAR-based approaches. A comparative analysis of the performance of the two point-cloud technologies has never been attempted in Australian plantations. In this study, we compared the performance of LiDAR-based and AP-based point clouds for estimating total recoverable volume in a Pinus radiata plantation at Springfield in north-eastern Tasmania, using volume data collected by harvesting machines as a reference. Our results showed that AP point clouds can be used for mapping total recoverable volume in P. radiata plantations with levels of accuracy that are comparable to LiDAR-based estimates. Plot-level relative root mean squared error (RMSE%) values were 23.85% for LiDAR and ranged from 22.07% to 27.10% for the three AP dense point-cloud settings evaluated. At the stand level, RMSE% decreased to 9.86% and 8.91% for LiDAR and AP, respectively. Both LiDAR-based and AP-based modelled volumes showed a close agreement with volumes measured using harvester head data, demonstrating the potential of AP technology for the management and planning of forestry operations in softwood plantations.     

建立气传花粉日播报平台对过敏性鼻炎防治的意义及相关因素分析

目的：收集呼和浩特气传花粉数据,分析其分布特征及气候影响因素,建立花粉浓度日播报平台,指导患者有效防护,为临床提供辅助诊疗引导。方法：花粉采集仪收集花粉,显微镜下进行阅片计数,记录同期气象因素,通过以微信公众平台为主的多种播报途径进行花粉日播报。结果：共收集花粉26825粒,鉴别种属18类,花粉播散存在春季和夏秋季两个高峰段,其分布规律与每日温差正相关,平台用户流量与花粉浓度趋势走形呈一致性变化,夏秋季用户流量峰值较春季高。结论：呼和浩特气传花粉存在两个高峰段,花粉浓度同每日温差存在正相关,花粉浓度日播报可为临床提供辅助诊疗引导。     

基于聚合酶链式反应-变性梯度凝胶电泳法的博物馆展厅空气细菌群落动态监测

目的了解博物馆展厅内空气中细菌数量和种类的动态变化。方法于2015年6月至2017年5月连续24个月在博物馆同一展厅同一位置进行空气微生物采样,采用培养法对空气微生物菌落总数进行检测,并进一步采用聚合酶链式反应-变性梯度凝胶电泳法(PCR-denaturing gradient gel electrophoresis,PCR-DGGE)对空气中细菌的组成种类进行分析。结果监测的两年间展厅空气中细菌数量有波动,菌落总数为78～616 CFU/m^3之间,主要种类有5～15种,种类变化存在季节性差异。马胃葡萄球菌(Staphylococcus equorum)、铜绿假单胞菌(Pseudomonas aeruginosa)、溶血性葡萄球菌(Staphylococcus hominis)、假单胞菌属(Pseudomonas sp.)在24个月内均有检出,且未随季节和人员的不同而变化。结论持续两年的监测显示博物馆展厅空气中细菌在种类和数量上呈现季节性变化,但已在一定程度上形成稳态。