Browsing by Subject "FLOW-RATE"

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  • Cai, Runlong; Jiang, Jingkun; Mirme, Sander; Kangasluoma, Juha (2019)
    Measuring aerosol size distributions accurately down to similar to 1 nm is a key to nucleation studies, and it requires developments and improvements in instruments such as electrical mobility spectrometers in use today. The key factors characterizing the performance of an electrical mobility spectrometer for sub-3 nm particles are discussed in this study. A parameter named as Pi is proposed as a figure of merit for the performance of an electrical mobility spectrometer in the sub-3 nm size range instead of the overall detection efficiency. Pi includes the overall detection efficiency, the measurement time in each size bin, the aerosol flow rate passing through the detector, and the aerosol-to-sheath flow ratio of the differential mobility analyzer. The particle raw count number recorded by the detector can be estimated using Pi at a given aerosol size distribution function, dN/dlogd(p)( ). The limit of detection for the spectrometer and the statistical uncertainty of the measured aerosol size distribution can also be readily estimated using Pi. In addition to Pi, the size resolution of an electrical mobility analyzer is another factor characterizing the systematic errors originated from particle sizing. Four existing electrical mobility spectrometers designed for measuring sub-3 nm aerosol size distributions, including three scanning/differential mobility particle spectrometers and one differential mobility analyzer train, are examined. Their optimal performance is evaluated using Pi and the size resolution. For example, the Pi value and the size resolution of a diethylene-glycol differential mobility particle spectrometer for 1.5 nm particles are 8.0 x 10(-4) cm(3) and 5.7, respectively. The corresponding relative uncertainty of the measured size distribution is approximately 9.6% during an atmospheric new particle formation event with a dN/dlogd(p) of 5 x 10(5) cm(-3) . Assuming an adjustable sheath flow rate of the differential mobility analyzer, the optimal size resolution is approximately 5-9 when measuring atmospheric new particle formation events.
  • Lavorini, Federico; Chudek, Jerzy; Gálffy, Gabriella; Pallarés-Sanmartin, Abel; Pelkonen, Anna S.; Rytilä, Paula; Syk, Jörgen; Szilasi, Maria; Tamási, Lilla; Xanthopoulos, Athanasios; Haahtela, Tari (2021)
    Asthma and chronic obstructive pulmonary disease (COPD) are major causes of morbidity and mortality worldwide. Optimal control of these conditions is a constant challenge for both physicians and patients. Poor inhaler practice is widespread and is a substantial contributing factor to the suboptimal clinical control of both conditions. The practicality, dependability, and acceptability of different inhalers influence the overall effectiveness and success of inhalation therapy. In this paper, experts from various European countries (Finland, Germany, Hungary, Italy, Poland, Spain, and Sweden) address inhaler selection with special focus on the Easyhaler® device, a high- or medium–high resistance dry-powder inhaler (DPI). The evidence examined indicates that use of the Easyhaler is associated with effective control of asthma or COPD, as shown by the generally accepted indicators of treatment success. Moreover, the Easyhaler is widely accepted by patients, is reported to be easy to learn and teach, and is associated with patient adherence. These advantages help patient education regarding correct inhaler use and the rational selection of drugs and devices. We conclude that switching inhaler device to the Easyhaler may improve asthma and COPD control without causing any additional risks. In an era of climate change, switching from pressurized metered-dose inhalers to DPIs is also a cost-effective way to reduce emissions of greenhouse gases. [MediaObject not available: see fulltext.].