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Events for April 23, 2009
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How Viruses Make New Viruses: A Single Molecule View
Thu, Apr 23, 2009 @ 12:45 PM
Mork Family Department of Chemical Engineering and Materials Science
Conferences, Lectures, & Seminars
Mork Family Department of Chemical Engineering and Materials Science Distinguished Lecture SeriesPresentsProfessor Rob PhillipsApplied Physics and Mechanical Engineering California Institute of Technology, Pasadena, California 91125Abstract:
Viruses have enormously rich and varied life cycles. Bacterial viruses have a hallowed position in the development of modern biology and recently have become the subject of intensive physical investigation. Using single-molecule techniques, it has become possible to examine viruses both while they package and eject their DNA. One of the intriguing aspects of these processes is that they bring large forces (greater than 50 pN) into play. My talk will give a general introduction to viruses and their life cycles and will then focus on simple physical arguments about the forces that attend viral DNA packaging and ejection, predictions about the ejection process and single-molecule measurements of ejection itself.Location: Olin Hall of Engineering (OHE) - 122
Audiences: Everyone Is Invited
Contact: Petra Pearce Sapir
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Identifying Remediation Techniques and Quantifying TMDL Regulated Pollutants for ....
Thu, Apr 23, 2009 @ 01:00 PM - 04:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Stormwater Runoff in the Los Angeles RegionOral Defense, Jaime Sayre, Ph.D. Student, Sonny Astani, Department of Civil and Environmental Engineering, USCAbstract:The goals for Los Angeles and southern California water quality included evaluating the capture, treatment, and reuse of stormwater through groundwater infiltration; assessing the costs of stormwater quality control; monitoring virus numbers in stormwater; and developing improved methods for measuring pollutant concentrations.The cost benefit analysis indicated that the treatment of larger regions as one watershed reduces the initial cost to employ the stormwater best management practices, that willingness to pay and value of ecological improvements vary and are difficult to quantify. The new cost estimated for both structural and non-structural BMPs was $12.6 billion, and the total benefit of the BMPs and improvement to the environment was $21.3 billion, for a net benefit of $8.7 billion.
The virus study was less conclusive, finding rather uniform virus counts in the tens of millions per milliliter. Previous research found human viruses in significantly smaller concentrations (1-100 per mL), suggesting that the total counts may reflect high background concentrations of non-human viruses from sources that are not coincident with sources of pollution.Using two passive samplers, polyethylene devices (PEDs) and solid phase microextraction (SPME) fibers, hydrophobic organic contaminants (HOCs) were quantified and the samplers were compared. PEDs were calibrated for 16 model HOCs (PCBs, PAHs, DDTs, and chlordanes) for both partitioning coefficients (KPEW) and exchange rate kinetics (ke). Triplicate PEDs and SPME fibers were exposed for 45 days to a concentration series of water spiked with nine model hydrophobic organic compounds. Model HOCs in SPME were higher than those in PEDs, with SPME measurements matching water concentrations more closely than PEDs for PCBs and chlorinated pesticides. For PAHs, PED and SPME measurements bracketed LLE water concentrations with no apparent bias. The number of detections using PEDs was greater for concentrations less than 0.1 ng/L, indicating that PEDs afford greater sensitivity than single SPME fibers. Researchers are continuing to investigate PEDs, including the use of pre-loaded reference compounds to quantify the "extent" of equilibrium vs. exposure time and possible variations due to polyethylene manufacturer and process.Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
