Description:

Speaker: Rachel Watson, Notestein Lab
Title: Ethylene Carbonylation Over MoS2 and PdS
Abstract
Carbonylation is an important class of reactions in the synthesis of many fine chemicals, although relatively few catalysts exist for the conversion of C2 species into the corresponding C3 carboxylic acids and esters. Of these systems, metal sulfide catalysts may be promising, especially for promoter-free carbonylation. Metal sulfides have many uses in hydrotreating and homologation reactions but have been studied minimally for carbonylation. In this work, we discuss a promoter-free ethylene carbonylation route to propionates over transition metal sulfide catalysts in water.
Ethylene carbonylation in water over sulfide catalysts is very clean, in most cases giving only propionic acid and its anhydride, ethanol, and propanaldehyde. In general, noble metal sulfides are very active towards propanaldehyde, while the MoS2 catalysts are relatively selective to propionic acid. MoS2, and PdS have been investigated. In addition to reporting basic catalyst performance metrics, reactivity will be correlated with specific surface area, catalyst reducibility, and other properties. This work presents a fresh approach to the long standing and heavily studied C2 carbonylation challenge.

Speaker: Ying Yu, Broadbelt Lab
Title: Mechanistic study of regioselective ring-opening reactions of mono-substituted epoxides using Lewis acid catalysts

Abstract
Polyether polyols are important intermediates in the polyurethane industry and are typically made by reacting mono-substituted epoxides with polyalcoholic initiators in the presence of a catalyst.1 While conventional catalysts such as potassium hydroxide and double metal cyanide catalysts result in less reactive polyols terminated with secondary hydroxyl groups, Lewis acid catalysts, aryl boranes, has been found to achieve high regioselectivity towards the desired primary alcohol functionality.2 In addition, recent experiments revealed significant water effects on retarding the ring-opening rate and additive effects in enhancing the regioselectivity towards primary alcohol products. However, the detailed catalytic mechanism is not fully understood. In addition, the catalytically active species is still unclear based on existing experimental methods that are unable to monitor the in situ speciation of this complex reaction system.

In this study, a novel catalytic mechanism was proposed for a model system using tris (pentafluorophenyl) borane (FAB) as catalyst and was validated by an ab initio study together with comprehensive microkinetic modeling. Density functional theory (DFT) was used to investigate two classes of possible reactions: competitive binding reactions of ligands to the catalyst, and the catalytic ring-opening reactions. We identified several possible catalyst forms that contribute to ring-opening reactions with different regioselectivities. The microkinetic model validated the proposed mechanism against experimental results and was used to generate accurate predictions under other reaction conditions. Analysis of speciation and net reaction rates elucidated the effects of water concentration on reactivity through a catalyst deactivation mechanism, and the effects of additives on regioselectivity as co-catalysts. Ultimately, this study facilitates greater understanding of catalyzed regioselective ring-opening reactions and provides a basis for the design of new catalytic systems to modulate ring-opening kinetics and the overall regioselectivity.

References:
(1) Chinn, H. K., A.; Loechner, U. SRI Consulting 2006.

(2) (a) Satake, M. US6531566B1, 2003. (b) Chakraborty, D.; Rodriguez, A.; Chen, E. Y. X. Macromolecules 2003, 36, 5470-5481. (c) Chandrasekhar, S.; Reddy, C. R.; Nagendra Babu, B.; Chandrashekar, G. Tetrahedron Lett. 2002, 43, 3801-3803. (d) Raghuraman, A.; Babb, D.; Miller, M.; Paradkar, M.; Smith, B.; Nguyen, A. Macromolecules 2016, 49, 6790-6798.

Speaker: Jennifer Greene, Broadbelt and Tyo Labs
Title: Optimizing Ensemble Modeling Framework to Generate Kinetic Models of Metabolism

Abstract
Developing reliable, predictive kinetic models of metabolism is a difficult yet necessary priority toward understanding and deliberately altering cellular behavior. However, many of the in vivo kinetic parameters and rate laws governing individual enzymes are unknown. Ensemble Modeling (EM) was developed to circumnavigate this challenge and effectively sample the large kinetic parameter solution space using consistent experimental datasets. Unfortunately, EM, in its current form, requires long solve times to complete and often leads to unstable kinetic model predictions. Furthermore, these limitations scale prohibitively with increasing model size. As larger metabolic models are developed with increasing genetic information and experimental validation, the demand to incorporate supplemental kinetic information increases. Therefore in this work, we have begun to tackle the challenges of EM by introducing additional steps to the existing method framework specifically through reducing computation time and optimizing parameter sampling. We first reduce the structural complexity of the network by removing dependent species, and second we sample locally stable parameter sets to reflect realistic biological states of cells. Lastly, we presort the screening data to eliminate the most incorrect predictions in the earliest screening stages, saving further calculations in later stages. Our complementary improvements to the current EM framework are easily incorporated into concurrent EM efforts and broaden the application opportunities and accessibility of kinetic modeling across the field.

Description:

Co-Sponsored with the Center for Water Research

Speaker: Dr. Richard Ambrose, UCLA

Title: Stormwater capture meets urban ecology: The role biofilters can play in enhancing biodiversity and ecosystem services in cities

Abstract

A variety of stormwater Best Management Practices (BMPs) are being deployed extensively in urban areas to reduce the negative effects of stormwater runoff. The design of these BMPs focus on capturing and treating stormwater, but some types of BMPs provide important co-benefits that are rarely recognized. Natural stormwater treatment systems, such as green roofs and biofilters, provide ecosystem services and ecological values not found in other types of BMPs. Many of these services, such as carbon sequestration, temperature moderation, air quality improvement, and aesthetics and other cultural services, provide valuable benefits to human health and well-being. In this talk, I will discuss some of the ecosystem services biofilters can provide as well as how they can support urban biodiversity. I will present preliminary results from our studies of biofilters in southern California and Melbourne, Australia. Since very little research has been conducted on biofilters themselves, I will also discuss how knowledge about urban green infrastructure can be applied to biofilters. Improved understanding of the factors influencing the ecosystem services or ecological values provided by natural treatment systems could lead to better designs that maximize these co-benefits along with stormwater functions. Although individually natural stormwater treatment systems are small, effective urban stormwater management will require an extensive network of BMPs so collectively they can make a significant contribution to urban ecology.

Richard Ambrose is a Professor in the Department of Environmental Health Sciences and the Institute of the Environment and Sustainability at UCLA. He received his B.S. from UC Irvine and his Ph.D. from UCLA. He spent seven years at the Marine Science Institute at UC Santa Barbara before returning to UCLA in 1992. He teaches graduate courses covering environmental assessment, restoration ecology, conservation biology, and the ecological effects of climate change. His research includes the restoration of degraded coastal habitats, monitoring change in rocky intertidal habitats, evaluating climate change impacts and adaptation strategies for coastal habitats, and evaluating the ecological aspects of biofilters used to capture and treat stormwater and other urban runoff. He serves on scientific advisory panels for many organizations, including the California Ocean Protection Council, California Coastal Commission, the Southern California Wetland Recovery Project, and the Santa Monica Bay Restoration Commission.

Description:

Speaker: Dr. Steven Little - University of Pittsburgh

Title: Controlling Controlled Release to MakeMedicine that Imitates Life

Abstract
Biomimetics (loosely defined) is the emulation of biological elements or processes to solve human problems. Our research group intends to reproduce the basic spatio-temporal information transfer that naturally occurs between the cells in our body to regulate biological form and function. As it stands, such is out of the reach of modern medicine. Accordingly, this seminar will introduce the idea that it is now possible to engineer synthetic constructs that can mimic the prose and context of cell-driven “communication” with the goal of inducing and/or regulating key biological processes. As just one example, simple temporal control over the release of specific growth factors can induce robust formation of specific tissues that naturally regenerate via stage-wise processes. This is possible using recent advances in the precise design of controlled release formulations. In the same way, this concept can also be used to reproduce spatial information that cells (and even tumors) employ to manipulate immunological responses. Collectively, these new tools can effectively reproduce biological context and have already shown significant promise as next-generation medical treatments in a variety of disease models where current medical treatments have no answer.

Dr. Steven Little is a William Kepler Whiteford Endowed Professor of Chemical and Petroleum Engineering, Bioengineering, Pharmaceutical Sciences, Immunology, Ophthalmology and The McGowan Institute for Regenerative Medicine at the University of Pittsburgh. He received his PhD in Chemical Engineering from MIT in 2005, with his thesis winning the American Association for Advancement of Science’s Excellence in Research Award. Dr. Little’s research has resulted to date in over 75 peer reviewed publications; 3 book chapters; 4 US Patents, 3 US Patents Pending and the founding of two spin-out companies located in Pittsburgh, PA. Dr. Little has delivered 55 invited talks including 6 plenary presentations and 5 keynote presentations. Dr. Little has been recognized by national and international awards including the Curtis W. McGraw Research Award from the ASEE, being elected as a fellow of BMES and AIMBE, a Carnegie Science Award for Research, the Society for Biomaterials’ Young Investigator Award, the University of Pittsburgh’s Chancellor’s Distinguished Research Award, being named a Camille Dreyfus Teacher Scholar, being named an Arnold and Mabel Beckman Young Investigator, and being elected to the Board of Directors of the Society for Biomaterials. In addition, Dr. Little’s exceptional teaching and leadership in education have also been recognized by both the University of Pittsburgh’s Chancellor’s Distinguished Teaching Award and a 2nd Carnegie Science Award for Post-Secondary Education. Dr. Little was also recently named one of Pittsburgh Magazine’s 40 under 40, a “Fast Tracker” by the Pittsburgh Business Times, and also one of only five individuals in Pittsburgh who are “reshaping our world” by Pop City Media. Dr. Little currently serves as the 12th Chairman of the Department of Chemical & Petroleum Engineering.

Description:

Weekly Seminar Series for the Department of Chemical and Biological Engineering.

Guest Speakers and student give lectures of their current research projects.

Description:

Weekly Seminar Series for the Department of Chemical and Biological Engineering.

Guest Speakers and student give lectures of their current research projects.