Besides Thermodynamics, What Other Factors Are Controlling Mineralization and Weathering at Near-Surface Conditions?
Henry Teng (George Washington University)
Please email Dr. You at firstname.lastname@example.org if you’d like to meet the speaker.
Natural process of mineral formation and dissolution at near-surface conditions are subject to various effects ranging from that of aqueous speciation to biological participation. As such complications arise for laboratory investigations of mineralization and weathering when thermodynamicd is considered the only driving force. Two case studies, one is solution chemistry effect on crystallization and the other microbially mediated dissolution, will be discussed in this presentation to highlight the complexity.
For mineralization, the classical approach states that the net growth rate of mono-molecular layers (ie, step velocity) is determined by the difference between fluxes of species attaching to and detaching from kinks along step edges. Such treatment leads to the development of the widely accepted understanding that step velocity depends solely on solution supersaturation. Yet, literature data from numerous cases argued strongly against this supposition. In this study, we conducted a series of in situ AFM experiments to interrogate the effect of solution chemistry parameters on step kinetics using calcite as a model system. We found step kinetics were strong affected by solution pH, ionic strength SI, and the [Ca2+]/[CO32-] ratio, and the impact differs in different cleavage directions. These observations suggest that, although supersaturation is the driving force for aqueous phase crystallization, solution chemistry plays critical roles in controlling the actual growth rate and needs to be taken into consideration in kinetic studies of crystallization.
For bio-weathering, complications are often associated with cell-mineral interfacial reactions because of physiology changes in microbes once becoming surface-bound and also because of the involvement of biomechanical forces in the case of fungal dissolution. In this study we examined lizardite [Mg3Si2O5(OH)4] dissolution by a native fungal strain in bulk media and at interface through determining the total metal release in culture, the pH local to surface-bound cells, and the material composition and structure beneath cell-colonized surfaces. We found that (1) cellular dissolution proceeds by a mechanism fundamentally different from that at the mineral-water interface, (2) only attached cells release siderophores, and (3) biomechanical forces of hyphal growth are indispensable for fungal weathering and strong enough to breach the mineral lattice. These results strongly suggest that fungal cell-promoted interfacial dissolution may have been significantly underestimated in the current understanding of microbial geochemistry.
Characterizing the interactions of the B-box E3 ligase with E2 conjugating enzyme: Learning about protein ubiquitination.
Michael Massiah (George Washington University)
Dr. Massiah will present recent work on the B-box domain from the human MID1 protein. The B-box domain may represent a new member of the ubiquitin E3 ligase, with similar fold as the RING-type E3 ligase. However, it has weaker activity. Despite this, it is require for the targeting and polyubiquitination of protein phosphatase 2A (a molecular master switch), alpha4, and the fused kinase. To understand how the B-box domain functions, NMR and fluorescence spectroscopy were used to characterize its interaction with the E2 enzyme, UbcH5, and mutagenesis to identify structural features that are important for ligase activity, and to engineer a more active E3 ligase. He will also discuss interesting observation how RNA affect MID1 E3 ligase activity.
Computational approaches to designing safer chemicals
Jakub Kostal (George Washington University)
Designing chemicals for targeted biological activity is a time-consuming and technologically challenging process. Computational methods have revolutionized drug discovery by being both fast, virtually screening vast chemical libraries to find drug candidates against biological targets of therapeutic interest, and accurate, providing state-of-the-art tools to optimize said candidates for greater activity. In developing pharmaceuticals, we seek to impart specific biological activity to a molecule but also to minimize any side effects caused by unintended activity. The latter is true for all commercial chemicals as our society has grown increasingly aware of the adverse effects chemicals can have on human and environmental health. Regrettably, to test every new chemical on animals to ensure its safety has been both economically and ethically unfeasible. In vitro and in silico methods offer a promising alternative; however, they generally lack the accuracy and robustness needed to replace animal tests. Inspired by the successes of computer-aided drug discovery, our group has focused on transforming said techniques to aid in safer chemical design. Mimicking Lipinski’s rules for druglikeness, we have developed broad, property-based guidelines that inform design of chemicals with minimal ecotoxicity. More recently, we have transformed statistical free energy perturbation calculations used in drug lead optimization to afford redesign of existing toxicants for increased safety.
Manipulating Light with Inorganic Nanoparticles
Hao Jing (George Mason University)
All about Energy Landscapes: Generating and Analyzing them to Predict and Characterize Protein Structure, Dynamics, and Function.
Amarda Shehu (George Mason University, Computer Science)
Research in my laboratory focuses on the design of novel algorithmic frameworks for elucidating biomolecular structures and their rearrangements as fundamental to understanding (dys)function, cellular processes, our own biology, and disease. Inspiration comes from a combination of biology and science and engineering fields that model dynamic systems. Specifically, we are driven by the energy landscape view, which allows modeling and understanding the behavior of intrinsically-dynamic molecular systems interconverting between structures with varying energies. In this talk I will share two recent directions of our research, one where we utilize protein energy landscapes to address a well-known but open problem known as decoy selection in template-free protein structure prediction, and one where we construct detailed representations of energy landscapes of healthy and diseased variants of a protein molecule of interest to human health. On the latter, I will demonstrate that computing and mining landscapes is allowing us to discover and categorize mechanisms via which pathogenic mutations alter protein dynamics and function in human disorders. This is bringing us closer to machines revealing part of the complex puzzle on how mutations alter biological activities.
Investigating the Activity of the Condensation Incompetent Ketosynthase (KS0) Domain in Type I Trans-AT Polyketide Synthase
Reham Al-Dhelaan, Ph.D. candidate (You group, George Mason Chemistry)
ACS on Campus, the American Chemical Society’s premier outreach program, is coming to George Mason University for a half-day event around science communication, publishing tips, and career talks! You’ll learn from ACS editors and local professionals tips and tools for publishing your research and sharing it with the public. Don’t miss out on our exciting career panel on jobs beyond the bench. You’ll hear from Prof. Erin Lavik, Associate Editor of Bioconjugate Chemistry, George Zaidan, Executive Producer of ACS Productions, Rebecca Hersher, reporter from NPR and more! There will also be plenty of time to network with your peers and make lasting professional connections.
***The event is FREE and open to all students and researchers studying the sciences. Coffee and refreshments are provided. Registration is highly recommended.***
Agenda, registration, and additional information can be found HERE.
ACS on Campus is sponsored by University Libraries and University Career Services.
|10:30 am||Erin Marcus||(Dr. Couch)|
|Inhibition of Klebsiella pneumoniae 1-deoxy-D-xylose 5-phosphate reductoisomerase (KpIspC) |
in the methylerythritol phosphate (MEP) pathway
|10:50 am||Mosufa Zainab||(Dr. Couch)|
|11:10 am||Benjamin McDowell||(Dr. Schreifels)|
|Electrospray ionization in mass spectrometry for analysis of volatiles|
|12:00 pm||Lunch||RSVP only|
|Planetary Hall 312|
DNA Self-Assembly: A Nanoscale Building Block for Bottom-up Fabrication
Divita Mathur, PhD. Naval Research Laboratory, Washington DC
The field of DNA nanotechnology has enabled scientists to realize and rapidly expand the ability to “build” objects at the nanoscale. With the help of a growing repository of DNA
self-assembling tools and strategies, it is possible to create two- and three-dimensional structures ranging from a few nanometers to micron-scale in size. The cumulative properties of
DNA, particularly its well-studied structural and physical behavior in response to varied conditions, its chemical and biological compatibility with a host of organic and inorganic
nanoparticles, and the predictable base pairing principles have enabled DNA nanotechnology to be widely adopted in many scientific disciples, namely, single-molecular studies, photonics,
plasmonics, synthetic biology, and healthcare.
In this work, I will highlight the state-of-the-art in the field of DNA nanotechnology with a focus on DNA self-assembly guided bottom up patterning of inorganic nanoparticles.
Following that I will briefly talk about some of our ongoing endeavors in leveraging different DNA nanostructures as vehicles for assembling three candidate particles with nanometer
precision, namely, DNA triangles with gold nanorods for the realization of architectures with interesting plasmonic properties, DNA icosahedra with quantum dots (QD) for enhancing
control over downstream QD fluorescence-based applications, and DNA “bricks” with fluorescent molecules such as Cyanine dyes for expanding our understanding of long range
energy transfer reactions.
Process intensification & consolidation for metropolitan wastewater treatment plants
Zhiwu (Drew) Wang, Ph.D., P.E. (Virginia Tech)
The rapid urbanization requires an urgent balance between the treatment capacity of the wastewater treat plants (WWTPs) and the urban population explosion. Techniques that allow “more to be done with less” become especially important for WWTPs confined within the metropolitan areas that serve 81% of the U.S. population. This presentation provides an overview of the efforts in Dr. Wang’s Manassas lab focusing on the development of sustainable biotechnologies for the intensification and consolidation of the liquid and solid waste treatment processes. Special emphases will be placed on the introduction of aerobic granulation that holds promise to replace the hundred-year old activity sludge process. These studies provide insight into engineered bioprocesses specifically tailored for urban biological wastewater treatment, with the overarching goal of advancing the environmental engineering research and serving the technical needs of industry stakeholders.
Dr. Wang is an Assistant Professor of Civil and Environmental Engineering at Virginia Tech. His research covers wastewater treatment, nutrient removal/recovery, solid waste anaerobic digestion, bioprocess modeling, and the conversion of waste into renewable energy and valuable bioproducts in the form of methane, ethanol, electricity, diesel and bioplastics. He holds a Ph.D. degree in Environmental Engineering from Nanyang Technological University, Singapore, and a P.E. degree in Environmental Engineering from Harbin Institute of Technology, China. He serves as the Co-Director of the Virginia Tech Center for Applied Water Research and Innovation (VT-CAWRI) and the associate editor of the Water Environment Research Journal.
If you are interested in meeting with Dr. Wang over lunch (at 12pm) or after the presentation, contact Dr. Van Aken.