The evolution of small aerosol particles accompanying the combustion of straw for energy production is investigated. A sampling equipment specially designed for field measurements is described and characterized. The aerosol is studied by low-pressure cascade impactor and scanning mobility particle sizer, the particle morphology by transmission electron microscopy, and the chemical composition by energy dispersive x-ray analysis. The combustion gas contains 3-500 m g /~m 3 of submicron particles with a mean diameter of approximately 0.3 pm. The particles consist of almost pure potassium chloride and sulphate. The formation mechanism is analyzed by a theoretical simulation of the chemical reactions and the aerosol change during cooling of the flue gas. It is concluded that some sulphation of KC1 occurs in the gas phase although the sulphate concentration is much lower than predicted by an equilibrium assumption. The theoretical simulation proves that the fine mode particles can be formed by homogeneous nucleation of either KC1 or K,S04 as the first step and further growth occurs by coagulation and diffusive condensation of both KC1 and K4S04 on existing particles. AEROSOL
There are potential advantages for using noninvasive methods instead of conventional approaches for measuring corticosterone (CORT) as a metric of stress. Two studies compared blood heterophil: lymphocyte (H:L) ratios, serum CORT, cecal content CORT (Study 1), colon content CORT (Study 2), and feather CORT concentrations for broiler chicks receiving drinking water with or without added CORT. On day 28, male broilers (N = 140) were provided tap water (Control group) or water containing 20 mg/L of CORT (CORT group) for up to 72 h. Body weight (BW), blood, feather, cecal, and colon content samples were collected from 10 birds from each treatment group at 0, 6, 12, 24, 30, 48, and 72 h. Data were analyzed with a JMP Pro ANOVA. Mean comparisons were analyzed on significant treatment effects using post hoc t-tests to compare control and CORT measures within each sampling time point. Pearson's pairwise correlations for all data were performed. A treatment by time interaction affected all measures in both studies. In both studies, CORT treatment reduced body weight and increased H:L ratios at later time points. In study 1 cecal content CORT concentrations were elevated with CORT treatment after 24 h, whereas in study 2 colon content CORT concentrations were elevated after 6 h. CORT treatment increased body and primary feather CORT and primary feather CORT increased with time in control groups in both studies. Serum CORT exhibited the lowest variability compared with all other sample sources used for determining CORT. Estimates of CORT by different methods were positively correlated. These results indicate that serum CORT concentrations most reliably reflect the CORT status of broilers, and that feather CORT concentrations demonstrated potential for estimating stress in broilers.
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