Materials Science and Engineering Commons^™

Development Of Nanostructured Austempered Ductile Cast Iron, Saranya Panneerselvam

Wayne State University Dissertations

Austempered Ductile Cast Iron is emerging as an important engineering materials in recent years because of its excellent combination of mechanical properties such as high strength with good ductility, good fatigue strength and fracture toughness together with excellent wear resistance. These combinations of properties are achieved by the microstructure consisting of acicular ferrite and high carbon austenite. Refining of the ausferritic microstructure will further enhance the mechanical properties of ADI and the presence of proeutectoid ferrite in the microstructure will considerably improve the ductility of the material.

Thus, the focus of this investigation was to develop nanostructured austempered ductile cast …

Zwitterionic Polymer Materials For Nanoparticle Stabilization, Cell Encapsulation And Anti-Fouling Coating, Wei Wang

Wayne State University Dissertations

Based on the superior anti-fouling property, the zwitterionic materials had great potential in applications such as medical implants, medical device coating, and marine coating industry. This thesis will focus on the applications of zwitterionic materials in stabilizing carbon nanoparticles, as implantable devices and durable coating on medical devices for long-term anti-microbial purposes. Chapter 2 of the thesis will discuss a simple method to synthesis carbon nanoparticles stabilized by zwitterionic polymers. Chapter 3 of the thesis reports the use of zwitterionic hydrogel to encapsulate islet of Langerhans to treat Type 1 diabetes. In Chapter 4 and 5, several methods were developed …

Bioreducible Layer-By-Layer Films For Gene Delivery, Lingxiao Xie

Wayne State University Dissertations

Layer-by-Layer (LbL) gene delivery system is fabricated by polycation and plasmid DNA alternative deposition based on electrostatic force between each other. This dissertation explored the relationship between LbL film assembly and disassembly. Demonstrated that the film disassemble process is closely related to film interior structure. LbL interlayer diffusion, which is caused by the polyelectrolytes own properties, such as polymer chain length, molecular weight, and charge density, can influence film growth mode. The interlayer diffusion is the main reason to lead fast and bulk DNA releasing of bioreducible LbL film. Preventing interlayer diffusion by inserting small diffusion coefficient polymer, such as …

Engineering Of Organic Nanocrystals By Electrocrystallization, Mohamed Kilani

Wayne State University Theses

This work discusses the experimental and theoretical methods used to control the morphology of nanocrystals. The hypothesis of the thermodynamic/kinetic control of the morphology was verified. We applied the electrocrystallization to make K(def)TCP nanocrystals and we tuned the electrochemical parameters to determine their influence on the nanocrystals morphologies. The characterization was mainly performed with AFM and FE-SEM. We presented in this work the possibility to control the morphology of K(def)TCP using the electrochemical parameters. The obtained shapes ranged from nanorods to rhombohedral shape, which is reported for the first time. The observed growth behavior was modeled and simulated with a …

Engineering Crystallization Via Phase Field Crystal Model, Deepak Joshi

Wayne State University Theses

Charge transfer complex material demonstrate morphological transitions while electro-crystallized on a substrate electrode under varying solute concentration and applied overpotential. It is hypothesized that variations in these parameters affect the thermodynamics and the kinetics of the electro-crystallization process. Having analysed these results, we resort to applying phase field crystal(PFC) model for our theoretical study. Our initial literature review laid foundation to consider PFC model as a powerful tool to study various aspect of crystallization process. In a PFC model the thermodynamic state of a system under study is defined in terms of Helmholtz free energy functional of density profile F=F[ρ(r)].Our …

Synthesis Of Discrete Transition Metal (Ni, Fe, Co, Mn) Phosphide Nanoparticles: Compositional Effect On Catalytic And Magnetic Properties, Da Li

Wayne State University Dissertations

This dissertation research is focused on the synthesis, characterization of binary and ternary transition metal (Ni, Co, Fe, Mn) phosphide nanomaterials and their catalytic and magnetic properties.

A phase-control strategy enabling the arrested-precipitation synthesis of nanoparticles of Ni5P4 and NiP2 is presented. The composition and purity of the product can be tuned by changing key synthetic levers, including the metal precursor, the oleylamine (OAm) and Trioctylphosphine (TOP) concentrations, temperature, time and the presence or absence of a moderate temperature soak step to facilitate formation of Ni and/or Ni-P amorphous nanoparticle intermediates.

New CoxFe2-xP nanoparticles (0 ≤ x ≤ 2), Co2-xMnxP …

Biomaterials Approaches For Utilizing The Regenerative Potential Of The Peripheral Nerve Injury Microenvironment, Melissa Renee Wrobel

Wayne State University Dissertations

Clinically available treatments are insufficient to achieve full functional recovery in large (>3cm) peripheral nerve injuries (PNI). The objectives in this thesis were 1) to study often overlooked elements of intrinsic PNI repair including release of inhibitory CSPGs and post-injury responses of inflammatory macrophages and dedifferentiated Schwann cells; 2) to create biomaterial scaf-folds featuring topographical and adhesive cues to enhance neurite outgrowth; and 3) to test the ability of those cues to direct macrophages and Schwann cells towards a pro-regenerative phe-notype. It is hypothesized that recapitulating the positive and negative cues of the PNI microenvi-ronment can better improve regeneration. …