Engineering Commons^™

Insights For Catalyst Design: A Systematic Investigation Of The Morphological Dependence Of Catalytic And Photocatalytic Activity For Nanostructured Titania, Paul Andrew Pepin

Publicly Accessible Penn Dissertations

Studies of the thermal and photocatalytic properties of single crystal materials have proven to be useful in elucidating how surface structure influences photocatalytic activity for a range of reactions. While the use of well-defined single-crystal surfaces as model photocatalysts has many advantages, this approach also has some limitations since they do not allow one to study cooperative effects between different exposed crystal planes and how preferential migration of photogenerated charge carriers to different surfaces influences activity. To overcome these limitations while still using materials with well-defined surfaces, the research described in this dissertation seeks to understand the relationships between nanostructure ...

Diverse Colloidal Crystals And Clusters Formed By Dna-Grafted Spheres Via Self-Assembly, Yifan Wang

Publicly Accessible Penn Dissertations

Meta-materials with novel photonic, phononic, thermal, and mechanical properties are considered as future materials for new applications. Colloidal crystals are meta-materials made from assemblies of building blocks that are not found in naturally occurring materials. Unlike atoms and molecules, such building blocks could be obtained from DNA-coated colloids which have feasible and adjustable interaction strengths as well as facilitating a further DNA-induced self-assembly into different geometries and structures. This DNA colloidal self-assembly prototyping process could be utilized as a fast and effective way for fabricating different structures, which shed light on the industrial production of the meta-materials.

In this work ...

Improving Performance Of Infiltrated Sofc Cathodes Via Scaffold Engineering And Catalyst Surface Engineering, Yuan Cheng

Publicly Accessible Penn Dissertations

Solid Oxide Fuel Cells (SOFCs) are energy-generating devices operating at elevated temperatures. At their cathode sides, oxygen molecules reduce into oxygen ions and then transport to the anode side through a solid-state ceramic membrane (typically, Yttria-Stabilized Zirconia (YSZ)). At their anode side, the fuels react with the oxygen ions and then release electrons to the external circuit. Always, it is the cathode that has the slowest reaction kinetics, such it contributes the largest resistance in the entire device.

The state-of-the-art cathode materials are typically perovskite-phase ceramic materials, such as Strontium-doped Lanthanum Manganate (LSM), Strontium-doped Lanthanum Ferrite (LSF) and Strontium-doped Lanthanum ...

Anisotropy And Aggregation In Self-Assembled Polymer Nanocomposites, Benjamin Joseph Lindsay

Publicly Accessible Penn Dissertations

Polymer nanocomposites (PNC) are an exciting class of materials with a wide array of applications. Whether the desired application involves isotropic or anisotropic polymer and particle structures, controlling aggregation and/or anisotropy in PNCs remains crucial to engineering composites with desired properties. Many methods have been developed to address these challenges. Three methods of interest include 1) the inclusion of anisotropic particles in the PNC, 2) block copolymers used as anisotropic templates to pattern particles, and 3) particle surface chemistry modification to increase dispersion. Significant experimental progress has been made in all three of these methods, but deeper fundamental understanding ...

A Heterogeneous And Multiscale Modeling Framework To Develop Patient-Specific Pharmacodynamic Systems Models In Cancer, Alokendra Kumar Ghosh

Publicly Accessible Penn Dissertations

Systems models of key signaling pathways in cancer have been extensively used to under-

stand and explore the mechanisms of action of drugs and growth factors on cancer cell

signaling. In general, such models predict the effect of environmental stimuli (both chemical such as for e.g., growth factor and drugs as well as mechanical such as matrix stiffness)

in terms of activities of proteins such as ERK or AKT which are important regulators of cell

fate decisions. Although such models have helped uncover important emergent properties

of signaling networks such as ultrasensitivity, bistability, and oscillations, they miss many

key ...

Selective Conversion Of Biomass Model Compounds Using Promoted Metal Catalysts, Cong Wang

Publicly Accessible Penn Dissertations

ABSTRACT

SELECTIVE CONVERSION OF BIOMASS MODEL COMPOUNDS USING PROMOTED METAL CATALYSTS

Cong Wang

Raymond J. Gorte

Extensive research and development have gone into modern biomass upgrading in order to mitigate the environmental concerns and other impending challenges associated with conventional fuels and chemicals. The phenolic and furanic compounds produced by primary upgrading processes represent a collection of biomass intermediates that still preserve the valuable chemical structures, but they require further upgrading due to unfavorable oxygen contents and unstable functional groups. This dissertation seeks to demonstrate the viability of utilizing bimetallic and metal-oxide-promoted metal catalysts to further upgrade biomass-derived oxygenates by ...

Polymer Infiltration Under Extreme Confinement, David Ring

Publicly Accessible Penn Dissertations

Polymer nanocomposites with high nanoparticle loadings are ubiquitous in nature but difficult to replicate synthetically. A simple technique to create such polymer nanocomposites is to form a bi-layer of a nanoparticle thin film atop a polymer thin film and anneal above the polymer glass transition temperature to induce wicking. This Capillary Rise Infiltration (CaRI) of polymers into nanoparticle thin films is a promising method to create interesting biomimetic composites with enhanced material properties, but also raises important theoretical questions about confinement, capillarity, and polymer dynamics. Therefore, I use molecular dynamics simulations (MD) and continuum theory to understand the impact of ...