A thermal-dissociation–cavity ring-down spectrometer (TD-CRDS) for the detection of organic nitrates in gas and particle phases

A thermal-dissociation–cavity ring-down spectrometer (TD-CRDS) was developed to measure NO2, peroxy nitrates (PNs), alkyl nitrates (ANs), and HNO3 in the gas and particle phase, built using a commercial Los Gatos Research NO2 analyzer. The detection limit of the TD-CRDS is 0.66 ppb for ANs, PNs, and HNO3 and 0.48 ppb for NO2. For all four classes of NOy, the time resolution for separate gas and particle measurements is 8 min, and for total gas + particle measurements it is 3 min. The accuracy of the TD-CRDS was tested by comparison of NO2 measurements with a chemiluminescent NOx monitor and aerosol-phase ANs with an aerosol mass spectrometer (AMS). N2O5 causes significant interference in the PN and AN channel under high oxidant concentration chamber conditions, and ozone pyrolysis causes a negative interference in the HNO3 channel. Both interferences can be quantified and corrected for but must be considered when using TD techniques for measurements of organic nitrates. This instrument has been successfully deployed for chamber measurements at widely varying concentrations, as well as ambient measurements of NOy.

Thermal dissociation cavity ring-down spectrometer (TD-CRDS) for detection of organic nitrates in gas and particle phase

A thermal dissociation – cavity ring-down spectrometer (TD-CRDS) was built to measure NO2, peroxy nitrates (PNs), alkyl nitrates (ANs), and HNO3 in the gas and particle phase. The detection limit of the TD-CRDS is 0.66 ppb for ANs, PNs, and HNO3 and 0.48 ppb for NO2. For all four classes of NOy, the time resolution for separate gas and particle measurements is 8 minutes and for total gas + particle measurements is 3 minutes. The accuracy of the TD-CRDS was tested by comparison of NO2 measurements with a chemiluminescent NOx monitor, and aerosol-phase ANs with an Aerosol Mass Spectrometer (AMS). N2O5 causes significant interference in the PNs and ANs channel under high oxidant concentration chamber conditions, and ozone pyrolysis causes a negative interference in the HNO3 channel. Both interferences can be quantified and corrected for, but must be considered when using TD techniques for measurements of organic nitrates. This instrument has been successfully deployed for chamber measurements at widely varying concentrations, as well as ambient measurements of NOy.

Factors Affecting Spermatozoa Motility Analysis using CASA

Motility is a very important parameter to determine the quality of semen. Spermatozoa motility assessment can be done manually (subjectively) or with CASA. The superiority of motility assessment using CASA compared to manually is more objective, accurate, fast, efficient and able to provide detailed motility of spermatozoa. However, in implementation, assessments with CASA produce varied data. So far, there has not been a spermatozoa motility standard with CASA, except by minimizing variations in the factors that influence the results of analysis with CASA. The purpose of this paper is to describe factors that affecting spermatozoa motility analysis using CASA to reach optimal motility analysis. Some influencing factors include: CASA settings, semen diluent, spermatozoa concentration, chamber, analyst, sample preparation and analysis time. Recommendation standard motility assessments using CASA include: experienced and consistent analysts, sample preparation properly (mixing, pipeting and sampling), spermatozoa concentration of 20 million / ml, consistent in chamber type (conditioned 37°C), semen diluents and CASA settings (frame rate of 60 Hz and frame per field 30) and fast implementation of analysis (<2 minutes).

Reducing nitrogen crossover in microbial reverse-electrodialysis cells by using adjacent anion exchange membranes and anion exchange resin

An additional low concentration chamber using two adjacent anion exchange membranes filled 50% with resin reduced nitrogen crossover to the anode.