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The measure of volumetric flow rate is utilized to calculate sampling volume and airborne concentration in integrated air sampling. Consequently, calibration of the sampling train to verify volumetric flow rate is critical. The relation between sampler pressure drop and volumetric flow rate was studied in support of using the former rather than the latter for the calibration of sampling trains. Four types of respirable cyclones, two filter brands with membrane samples of the same and different lots of production, and two personal pump types were considered as components of the sampling trains under consideration. Volumetric flow rate and pressure drop were measured under controlled conditions in a cylindrical jar designed for these determinations. For all the configurations considered, the relation between sampler pressure drop and standard volumetric flow rate was linear. Intra-sample selection of cyclones of the same type and pump type did not create significant differences in sampler pressure drop. Filter selection, regardless of brand or production lot, did create linear response functions that had statistically different slopes and intercepts. When grouped by cyclone type and filter brand, the sampler pressure drop at the flow rate recommended by the cyclone's manufacturers showed variability that was not normally distributed. The recommended central tendency estimate of pressure drop is the median value, with point estimates that should be specific to a cyclone type / filter brand combination. [ABSTRACT FROM AUTHOR]

The article talks about higher levels of plasma interleukin-6 being associated with lower blood oxygenation level dependent (BOLD) responses to working memory load among older adults.

Myonuclei gained during exercise-induced skeletal muscle hypertrophy may be long-lasting and could facilitate future muscle adaptability after deconditioning, a concept colloquially termed "muscle memory." The evidence for this is limited, mostly due to the lack of a murine exercise-training paradigm that is nonsurgical and reversible. To address this limitation, we developed a novel progressive weighted-wheel-running (PoWeR) model of murine exercise training to test whether myonuclei gained during exercise persist after detraining. We hypothesized that myonuclei acquired during training-induced hypertrophy would remain following loss of muscle mass with detraining. Singly housed female C57BL/6J mice performed 8 wk of PoWeR, while another group performed 8 wk of PoWeR followed by 12 wk of detraining. Age-matched sedentary cage-dwelling mice served as untrained controls. Eight weeks of PoWeR yielded significant plantaris muscle fiber hypertrophy, a shift to a more oxidative phenotype, and greater myonuclear density than untrained mice. After 12 wk of detraining, the plantaris muscle returned to an untrained phenotype with fewer myonuclei. A finding of fewer myonuclei simultaneously with plantaris deconditioning argues against a muscle memory mechanism mediated by elevated myonuclear density in primarily fast-twitch muscle. PoWeR is a novel, practical, and easy-to-deploy approach for eliciting robust hypertrophy in mice, and our findings can inform future research on the mechanisms underlying skeletal muscle adaptive potential and muscle memory.