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This article describes the development and characterization of a multi-stage preconcentrator/focuser (PCF) module designed to be integrated with a microfabricated gas chromatograph (µGC) for autonomous, in situ determinations of volatile organic compounds. The PCF module has been optimized specifically for the determination of trichloroethylene (TCE) vapors at low- or sub-parts-per-billion concentrations in the presence of common indoor air co-contaminants in residences at risk of vapor intrusion (VI) from surrounding TCE-contaminated soil. It consists of three adsorbent-packed devices arranged in series: a pre-trap of conventional (tubular metal) design for capturing interferences with vapor pressures <3 torr; a high-volume sampler, also of conventional design, for capturing (and transferring) TCE and other compounds with vapor pressures within the range of ~3 to 95 torr; and a microfocuser (µF) consisting of a micromachined Si chamber with an integrated microheater for focusing and injecting samples into the separation module. The adsorbent masses, sampling and desorption flow rates, and heating profiles required for selective, quantitative capture and transfer/injection of TCE are determined for each of the devices, and the assembled PCF module is used to analyze a test atmosphere containing 200 parts-per-trillion of TCE and 27 relevant co-contaminants with a conventional downstream capillary column and electron-capture detector. An average TCE transfer efficiency of 107% is achieved for a 20 L air sample, with a preconcentration factor of ~800,000.

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Thailand’s first national steps challenge has been implemented in 2020 with the goal to raise the level of physical activity nationwide by monitoring achievements through a smartphone application. This study examined the daily step counts of participants in the first national steps challenge. Six data points from 186,653 valid participants were retrieved and analyzed in five periods using Poisson regression. The mean daily steps peaked at 3196 in Period 1, and steadily dropped to 1205 in Period 5. The daily steps per period were analyzed using the participants’ characteristics, such as the type of participant, sex, age, body mass index, and area of residence. The overall mean daily steps of the participants meant physical activity was far below the recommended level and tended to drop in later periods. The general population achieved significantly higher mean daily steps than public health officers or village health volunteers (24.0% by multivariate analysis). Participants who were female, younger (<45 years), obese (body mass index > 30), and living in rural areas had fewer mean daily steps (13.8%, 44.3%, 12.7%, and 14.7% by multivariate analysis, respectively), with statistical significance. In the future, the national steps challenge should be continuously implemented by counting all steps throughout a day, using more strategies to draw attention and raise motivation, advocating for more participants, as well as reporting the whole day step counts instead of distance.

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