The total electrical conductivity and the electron hole conductivity in solid CuCl, CuBr, and CuI between 250 and 450°C have been determined with help of ac measurements on samples between copper electrodes and dc polarization measurements on the cell
A method has been developed to estimate average concentrations and size distributions with a miniature passive aerosol sampler. To use the passive sampler, one exposes it to an environment for a period of hours to weeks. The passive sampler is intended to monitor ambient, indoor, or occupational aerosols and has potential utility as a personal sampler. The sampler is inexpensive and easy to operate and is capable of taking long-term samples to investigate chronic exposures. After sampling, the passive sampler is covered and brought to the lab. Scanning electron microscopy (SEM) and automated image analysis are used to count and size collected particles with d p > 0.1 ¹m. Alternatively, more advanced microscopy techniques can be used for ambient-pressure analysis or elemental characterization. Image analysis is used in conjunction with particle density and shape factors to obtain the mass ux as a function of aerodynamic diameter.
To better evaluate the health effects and indoor air quality impacts of nanoparticles generated by laser printers, measurements were made to characterize the number concentration, size distribution, morphology, and chemical composition of the emitted nanoparticles as a function of printer distance, idle time, "cold start" state, cartridge states, and number of pages printed. Emitted ion concentrations, nanoparticles, volatile organic compound (VOC) emissions, and toner particles were characterized using multiple analytical techniques. Finally, particle generation mechanisms and emission control strategies are discussed.Emission measurements were conducted using a commonly used black and white office printer (HP LaserJet4100) operating in a small (12 m 2 ) office conference room environment and a stainless steel environmental chamber of similar size. Particle concentrations and size distributions were monitored using condensation particle counter (CPC) and scanning mobility particle sizer (SMPS) directly above the printer and at distances of 1-2 m away. Emitted ion concentrations and VOCs were measured by ion density meter and thermal desorption gas chromatography/mass spectrometry (GC/MS), respectively. Aerosols emitted from the printer were collected using an electrostatic precipitator (ESP) sampler and analyzed with transmission electron microscopy/energy-dispersive X-ray spectroscopy (TEM/EDS). Toner particles from the LaserJet printer cartridge were analyzed using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), inductively coupled plasma/atomic emission spectroscopy (ICP/AES), scanning electron microscopy (SEM)/EDS, and TEM/EDS.
Wind tunnel experiments have been performed on a passive aerosol sampler. The sampler estimates average concentrations and size distributions using a deposition velocity model and the measured particle ux to the sampler. The small-scale wind tunnel incorporated a high-output aerosol generator that produced nonvolatile, polydisperse particles. An eight-stage impactor was connected to the tunnel with an isoaxial, isokinetic probe and was equipped with polycarbonate-membrane substrates saturated with oleic acid to minimize particle bounce. Before performing experiments, the tunnel's test section was characterized. Aerosol concentrations were determined to have a CV < 6%. The friction velocity, an index of turbulence, was found to range from 0.09 to 0.25 m/s for wind speeds of 1.5 to 5 m/s. The empirical portion of the deposition velocity model,°m, was determined as a function of particle size by minimizing the sum-of-squares difference between impactor and passive sampler across all size bins and all experiments. The relatively simple correlation is a function of the particle Reynolds number only. Precision was assessed by running three passive samplers simultaneously in each experiment.The tests yielded CV PM2:5 = 18:1% and CV PM10 = 32:2%. ANOVA tests were conducted on accuracy and precision to see whether they depended on wind speed, relative humidity, or aerosol concentration, and accuracy was tested with respect to particle size. No signi cant trends were observed. Sensitivity analysis showed that the volume shape factor is the most important of the mass and shape conversion factors. If SEM is used, the passive sampler will exhibit some error when sampling volatile aerosols. Because concentrations uctuate over time, long-term exposures measured by the passive sampler should be more accurate than conventional averages based on short-term samples.
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