University of Saskatchewan

About: University of Saskatchewan is a education organization based out in Saskatoon, Saskatchewan, Canada. It is known for research contribution in the topics: Population & Health care. The organization has 25021 authors who have published 52579 publications receiving 1483049 citations. The organization is also known as: USask.

Pyrolysis of Lignins: Experimental and Kinetics Studies

Abstract: Lignins are generally used as a low grade fuel in the pulp and paper industry. In this work, pyrolysis of Alcell and Kraft lignins obtained from the Alcell process and Westvaco, respectively, was carried out in a fixed-bed reactor and in a thermogravimetric analyzer (TGA) using helium (13.4 mL/min/g of lignin) and nitrogen (50 mL/min/g of lignin), respectively. The reaction temperature was increased from 300 to 1073 K, while the heating rates were varied from 5 to 15 K/min. The gaseous products mainly consisted of H2, CO, CO2, CH4, and C2+. With increase in heating rate from 5 to 15 K/min both lignin conversion and hydrogen production increased from 56 to 65 wt % and from 25 to 31 mol %, respectively for fixed-bed pyrolysis reaction of Alcell lignin at 1073 K, whereas at the same condition the conversion and hydrogen production increased from 52 to 57 wt % and from 30 to 43 mol % for Kraft lignin. The distributed activation energy model (DAEM) was used to analyze complex reactions involved in the lignin p...

Effects of Rapid Global Warming at the Paleocene-Eocene Boundary on Neotropical Vegetation

Abstract: Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago) event. We investigated the tropical forest response to this rapid warming by evaluating the palynological record of three stratigraphic sections in eastern Colombia and western Venezuela. We observed a rapid and distinct increase in plant diversity and origination rates, with a set of new taxa, mostly angiosperms, added to the existing stock of low-diversity Paleocene flora. There is no evidence for enhanced aridity in the northern Neotropics. The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide, in contrast to speculations that tropical ecosystems were severely compromised by heat stress.

Estimates of Threshold Wind Speeds for Snow Transport Using Meteorological Data.

Abstract: The threshold wind speed for snow transport is related to properties of the surface snowpack: snow particle bonding, cohesion, and kinetic friction. These properties are controlled by meteorological factors. A method is proposed that relates the threshold wind speed for the initiation of snow transport to standard surface meteorological observations. A complete dataset on the hourly threshold condition for snow transport as determined from visual observation was developed for 16 stations on the prairies of western Canada over six winters. The threshold wind speeds for wet snow transport are significantly different from those for dry snow transport. The majority of recorded threshold 10-m wind speeds ranged from 7 to 14 m s−1 with an average of 9.9 m s−1 for wet snow transport, and from 4 to 11 m s−1 with an average of 7.7 m s−1 for dry snow transport. The observations display a nonlinear but generally positive correlation between threshold wind speed and air temperature. An empirical model betwee...