Laurentian University , which was incorporated on March 28, 1960, is a mid-sized bilingual university in Greater Sudbury, Ontario, Canada.While primarily focusing on undergraduate programming, Laurentian also features the east campus of Canada's newest medical school - the Northern Ontario School of Medicine, which opened in 2005. Its school of Graduate Studies offers a growing number of graduate-level degrees. Laurentian is the largest bilingual provider of distance education in Canada. Wikipedia.
Cai M.,Laurentian University
Rock Mechanics and Rock Engineering | Year: 2010
By applying the Griffith stress criterion of brittle failure, one can find that the uniaxial compressive strength (σc) of rocks is eight times the value of the uniaxial tensile strength (σt). The Griffith strength ratio is smaller than what is normally measured for rocks, even with the consideration of crack closure. The reason is that Griffith's theories address only the initiation of failure. Under tensile conditions, the crack propagation is unstable so that the tensile crack propagation stress (σcd)t and the peak tensile strength rt are almost identical to the tensile crack initiation stress (σci) t. On the other hand, the crack growth after crack initiation is stable under a predominantly compressive condition. Additional loading is required in compression to bring the stress from the crack initiation stress rci to the peak strength σc. It is proposed to estimate the tensile strength of strong brittle rocks from the strength ratio of R = σc/|σt| = 8σc/ σci. The term σc/σci accounts for the difference of crack growth or propagation in tension and compression in uniaxial compression tests. σc/σci depends on rock heterogeneity and is larger for coarse grained rocks than for fine grained rocks. σci can be obtained from volumetric strain measurement or acoustic emission (AE) monitoring. With the strength ratio R determined, the tensile strength can be indirectly obtained from |σt| = σc/R = σci/8. It is found that the predicted tensile strengths using this method are in good agreement with test data. Finally, a practical estimate of the Hoek-Brown strength parameter mi is presented and a bi-segmental or multi-segmental representation of the Hoek-Brown strength envelope is suggested for some brittle rocks. In this fashion, the rock strength parameters like σt and mi, which require specialty tests such as direct tensile (or Brazilian) and triaxial compression tests for their determination, can be reasonably estimated from uniaxial compression tests. © Springer-Verlag 2009.
Walcarius A.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment |
Mercier L.,Laurentian University
Journal of Materials Chemistry | Year: 2010
A review with ca. 400 references is provided dealing with the use of mesoporous silica and organically-modified silica-based materials for removal of inorganic and organic pollutants from aqueous solutions. After having briefly discussed the interest of functionalized mesoporous silica for environmental remediation purposes, the various synthetic methods to prepare such nanoengineered adsorbents are described. Then, their application to the removal of heavy metal species, toxic anions, radionuclides, and a wide range of organic pollutants is presented in a comprehensive way with the help of extensive tables and some illustrating figures. © 2010 The Royal Society of Chemistry.
Persinger M.A.,Laurentian University
Current Medicinal Chemistry | Year: 2010
The myriads of molecular pathways that have been measured to understand the physical bases of neuronal and other cellular functions have exceeded classical comprehension. In the tradition of Bohr and Schrodinger, the hypothesis is developed that molecular pathways are simply epiphenomenal transports of quanta with increments in the order of 10-20 J. Experimental measurements of photon emissions from cell cultures and the serial steps of phosphorylation in general molecular pathways and transformations in chromophores supported this contention. This discrete value is also associated with action potentials, intersynaptic events, the biophysical bases of membrane potentials, the numbers of action potentials per cell from magnetic energy potential, and the interionic distances around membranes. Consideration of information as discrete increments of energy may allow greater experimental control and external intervention of pathways relevant to medicinal chemistry. © 2010 Bentham Science Publishers Ltd.
Cai M.,Laurentian University
Rock Mechanics and Rock Engineering | Year: 2011
Geotechnical design input parameters, such as in situ stress field, rock mass strength parameters and deformation modulus, are never known precisely. There are always uncertainties involved in these parameters, some are intrinsic and others are due to lack of knowledge or understanding of these parameters. To quantify the effects of these uncertainties on tunnel and cavern design, it is necessary to utilize probabilistic analysis methods. In the present study, a quantitative, probabilistic approach to use the Geological Strength Index (GSI) system for rock mass characterization is presented. It employs the block volume and a joint condition factor as quantitative characterization factors to determine the GSI values. The approach is built on the linkage between descriptive geological terms and measurable field parameters such as joint spacing and joint roughness, which are random variables. Using GSI values obtained from field mapping data, and in combination with the intact rock strength properties, the probability density distributions of rock mass strength parameters and elastic moduli of the jointed rock mass can be calculated using Monte Carlo method. Furthermore, probabilistic analysis of tunnel and cavern stability based on the variable input parameters is conducted employing the point estimate method. One example is given to illustrate how to consider the variability of in situ stress and the rock mass properties in tunnel and cavern design. The method presents an approach for systematic assessment of uncertainty in rock mass characterization in rock engineering, and it can assist us to better understand how uncertainty arises and how the rock support system design decision may be affected by it. © 2011 Springer-Verlag.
Zhang J.,Laurentian University
Microcirculation | Year: 2011
To obtain a better understanding of the beneficial effect of high plasma viscosity observed in hemodilution and resuscitation experiments, we conducted a computational study to investigate the suspending viscosity effect on red blood cell (RBC) dynamics and blood flow behaviors in microvessels. For single RBCs in simple shear or channel flows, RBCs appear more flexible as indicated by the tank-treading motion in shear flows and the strong transverse migration in channel flows. For the multiple RBC flows in straight channels, our results indicate no significant change with the suspending viscosity in stable flow structure and hemorheologic behaviors, under both constant flow and forcing conditions. However, due to the increase in apparent cell deformability in a more viscous medium, the cell-free layer (CFL) can be established in a shorter distance along the channel. Considering the multilevel bifurcated structure of the microvascular network, this change in CFL development distance may affect the phase skimming and RBC separation processes at the downstream bifurcation, and therefore the microcirculation performance in the tissue. This may suggest a possible mechanism for the high functional capillary density associated with a high suspending viscosity observed in experiments. © 2011 John Wiley & Sons Ltd.