Estimation of Nutrient Pollutant Loading of Each Particle Size Group into Dam Reservoir

1. When 103Ru-labelled Tris (1, 10-phenanthroline) ruthenium II chloride (103Ru-P) particulate marker in aqueous solution was added to the rumen of four steers given 5.5 kg grass hay/d at two-hourly intervals, the distribution of 103Ru-P marker among rumen particles of various sizes was the same at 4 h, 3 d and 7 d after administration, the concentration of 103Ru-P/g dry matter (DM) was inversely related to particle size and 0.30 of the 103Ru-P was associated with the DM of particles too large to be moved from the rumen at a meaningful rate. Thus, fractional outflow rate (FOR) of 103Ru-P would reflect, but was not a direct measure of, the FOR of the small particle pool in the rumen.2. When rumen digesta were labelled with 103Ru-P, placed in nylon cloth bags and incubated in vitro with unlabelled digesta, 59% of the 103Ru-P disappeared from the nylon bag in 24 h, and 74% in 48 h. Similar results were obtained when large particles (retained by a 3.2 mm mesh screen during wet sieving) from rumen digesta were subjected to this procedure.3. In a further experiment, the steers were given the hay in either the long or ground form and drinking water to which 10 g sodium chloride/l were, or were not, added.4. The FOR of 51CrEDTA in centrifuged rumen fluid was increased (P < 0.05) from 1.78 to 2.10/d by grinding of the hay diet, but was not influenced by the intake of an additional 257 g NaCl/d. The FOR values of 103Ru-P in mixed rumen digesta and organic 35S in micro-organisms were linearly correlated (P < 0.05) and were not affected (P < 0.05) by grinding and salt treatments. On average, the FOR of organic 35S in micro-organisms was 0.41 of that of 51CrEDTA in centrifuged rumen fluid and 0.85 of that of 103Ru-P in rumen digesta respectively.5. Grinding of the hay did not (P > 0.05) change the proportion of rumen DM (0.476–0.515) or faecal DM (0.107–0.153) retained by the 3.2 mm mesh and larger screens.6. FOR from the rumen of a given size group of particles was calculated as the ratio, estimated daily flow from the rumen of the size group: rumen pool of the group. With increasing particle size there was a progressive decline in FOR; values of FOR for groups of particles greater than 4.0 mm were negligible. If the rumen DM was considered to behave as two pools, the 3.2 mm mesh screen appeared to be an appropriate division between the large-particle and the small-particle DM pools.7. FOR of lignin present in mixed rumen digesta was 0.48 of the mean of the FOR values of the particle groups of the small-particle pool, while the FOR of lignin present in the small-particle pool was 0.92 of the mean small-particle FOR.

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Pollutant Loading of Different Particle Size Fractions Compared to the Pollutant Loads of Urban Stormwater Runoff Events

New Trends in Urban Drainage Modelling - Green Energy and Technology ◽

10.1007/978-3-319-99867-1_149 ◽

2018 ◽

pp. 864-868

Author(s):

Baum Philipp ◽

Dittmer Ulrich

Keyword(s):

Particle Size ◽

Stormwater Runoff ◽

Urban Stormwater ◽

Size Fractions ◽

Pollutant Loading ◽

Particle Size Fractions ◽

Pollutant Loads ◽

Urban Stormwater Runoff ◽

Runoff Events

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Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104972 ◽

1988 ◽

Vol 46 ◽

pp. 582-583

Author(s):

C. J. Chan ◽

K. R. Venkatachari ◽

W. M. Kriven ◽

J. F. Young

Keyword(s):

Particle Size ◽

Raw Materials ◽

Shape Change ◽

Microstructural Characterization ◽

Particle Size Effect ◽

Dicalcium Silicate ◽

Laser Melting ◽

Uniform Size ◽

Cell Shape Change ◽

Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

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Analytical Electron Microscopy study of two vehicle-aged automotive exhaust catalysts having dissimilar activities

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153336 ◽

1989 ◽

Vol 47 ◽

pp. 272-273

Author(s):

Sooho Kim ◽

M. J. D’Aniello

Keyword(s):

Electron Microscopy ◽

Particle Size ◽

Noble Metal ◽

Catalyst Deactivation ◽

Analytical Electron Microscopy ◽

Microscopy Study ◽

Metal Particles ◽

Automotive Exhaust ◽

Exhaust Catalysts ◽

Analytical Electron

Automotive catalysts generally lose-agtivity during vehicle operation due to several well-known deactivation mechanisms. To gain a more fundamental understanding of catalyst deactivation, the microscopic details of fresh and vehicle-aged commercial pelleted automotive exhaust catalysts containing Pt, Pd and Rh were studied by employing Analytical Electron Microscopy (AEM). Two different vehicle-aged samples containing similar poison levels but having different catalytic activities (denoted better and poorer) were selected for this study.The general microstructure of the supports and the noble metal particles of the two catalysts looks similar; the noble metal particles were generally found to be spherical and often faceted. However, the average noble metal particle size on the poorer catalyst (21 nm) was larger than that on the better catalyst (16 nm). These sizes represent a significant increase over that found on the fresh catalyst (8 nm). The activity of these catalysts decreases as the observed particle size increases.

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