The objective of this Major Research Instrumentation (MRI) award is to acquire an ultracentrifuge with high payload capacity. The ultracentrifuge uses centrifugation forces to speed up the measurement of hydrogeological and contaminant fate and transport properties. The ultracentrifuge G Force ranges from 0 to 250 with a maximum 20,000 G-lbs at 600 RPM. The acquired equipment will enhance research training and education at all levels, especially in the following areas: (a) hydraulic conductivity dependence on saturation level in low conductivity soils under unsaturated anisotropic conditions; (b) long-term deterioration of containment barriers; (c) characterization of hydrogeological and transport properties using anisotropy coefficient of porous media; (d) isotope transport in low permeability sediments in the vadose zone; and (e) chemical weathering of soils in areas used for carbon sequestration.
Measurement of unsaturated hydraulic conductivity in low conductivity soils can take years to be performed using most common approaches. Under steady-state centrifugation (SSC), which will be enabled through the acquisition of this equipment, the same measurement can be performed in a matter of days or even hours. The results will be widely disseminated to support research in the areas of underground contamination mitigation and groundwater protection. The instrumentation will be readily incorporated into undergraduate and graduate research and teaching programs available at CSULA.
This Major Research Instrumentation award was used to acquire a high-payload centrifuge (20,000 g-lbs.) to research several aspects of contaminant transport through the subsurface and groundwater. Steady-state centrifugation is used to accelerate physical processes being investigated. Thus, experiments that would take months or even years under normal gravity acceleration can be performed in weeks and even days depending on the media. Another advantage of using steady-state centrifugation is the ability to study physicochemical process affecting the transport of contaminants under controlled levels of saturation. This enables accelerated physical modeling of the unsaturated zone of the subsurface, also known as the vadose zone. Upon arrival of the centrifuge, which was delayed by almost 2 years due to required customization, other professors demonstrated the interest to perform research in fields ranging from sensor performance under high g-forces to water flow through pavement materials. Thus, the research team decided to modify the modeling box that was under development to test soils to enable other types of research. Late-last year the modeling box design was finalized and we are currently testing it before it can actually be used with the centrifuge. The magnitude of the forces involved (20,000 g-lbs.) created a number of obstacles in the development of such apparatus. We expect the centrifuge to be fully operational by mid-June, which will enable a number of research projects in various engineering and science fields. In fact, during this short preliminary phase of the project, 15 undergraduate and 3 graduate students and a post-doctoral researcher from civil, mechanical and electrical engineering have been involved in designing and testing the modeling box and its components. More than 70% of them belong to underrepresented groups in engineering. Research developed through the process has led to 5 peer-reviewed publications in journals and conference proceedings. We expect that the acquired centrifuge will generate research opportunities to 6 undergraduate and 4 graduate students every year and at the same time it will help advance the knowledge in the area of subsurface contamination and remediation, and groundwater quality, which is a matter of national security.
