University Distinguished Professors

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Becoming a University Distinguished Professor (UDP) is the highest honor that can be awarded to a faculty member at North Dakota State University. Research from these individuals can be found here. More information about University Distinguished Professors can be found at https://www.ndsu.edu/president/honors/distinguished_professors/

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Browsing University Distinguished Professors by browse.metadata.program "Materials and Nanotechnology"

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    An Insilico Design of Nanoclay Based Nanocomposites and Scaffolds In Bone Tissue Engineering
    (North Dakota State University, 2016) Sharma, Anurag
    A multiscale in silico approach to design polymer nanocomposites and scaffolds for bone tissue engineering applications is described in this study. This study focuses on the role of biomaterials design and selection, structural integrity and mechanical properties evolution during degradation and tissue regeneration in the successful design of polymer nanocomposite scaffolds. Polymer nanocomposite scaffolds are synthesized using aminoacid modified montmorillonite nanoclay with biomineralized hydroxyapatite and polycaprolactone (PCL/in situ HAPclay). Representative molecular models of polymer nanocomposite system are systematically developed using molecular dynamics (MD) technique and successfully validated using material characterization techniques. The constant force steered molecular dynamics (fSMD) simulation results indicate a two-phase nanomechanical behavior of the polymer nanocomposite. The MD and fSMD simulations results provide quantitative contributions of molecular interactions between different constituents of representative models and their effect on nanomechanical responses of nanoclay based polymer nanocomposite system. A finite element (FE) model of PCL/in situ HAPclay scaffold is built using micro-computed tomography images and bridging the nanomechanical properties obtained from fSMD simulations into the FE model. A new reduction factor, K is introduced into modeling results to consider the effect of wall porosity of the polymer scaffold. The effect of accelerated degradation under alkaline conditions and human osteoblast cells culture on the evolution of mechanical properties of scaffolds are studied and the damage mechanics based analytical models are developed. Finally, the novel multiscale models are developed that incorporate the complex molecular and microstructural properties, mechanical properties at nanoscale and structural levels and mechanical properties evolution during degradation and tissue formation in the polymer nanocomposite scaffold. Overall, this study provides a leap into methodologies for in silico design of biomaterials for bone tissue engineering applications. Furthermore, as a part of this work, a molecular dynamics study of rice DNA in the presence of single walled carbon nanotube is carried out to understand the role played by molecular interactions in the conformation changes of rice DNA. The simulations results showed wrapping of DNA onto SWCNT, breaking and forming of hydrogen bonds due to unzipping of Watson–Crick (WC) nucleobase pairs and forming of new non-WC nucleobase pairs in DNA.
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    Silicon Nanocrystals: Optical Properties and Self Assembly
    (North Dakota State University, 2018) Brown, Samuel
    Silicon nanocrystal’s (SiNCs) size dependent optical properties and nontoxic nature portend potential applications across a broad range of industries. With any of these applications, a thorough understanding of SiNC photophysics is desirable to tune their optical properties while optimizing quantum yield. However, a detailed understanding of the photoluminescence (PL) from SiNCs is convoluted by the complexity of the decay mechanisms, including a stretched-exponential relaxation and the presence of both nanosecond and microsecond decays. In this dissertation, a brief history of semiconductor nanocrystals is given, leading up to the first discovery of room temperature PL in SiNCs. This is then followed by an introduction to the various nanocrystal synthetic schemes and a discussion of quantum dot photophysics in general. Three different studies on the PL from SiNCs are then presented. In the first study, the stretched nature of the time dependent PL is analyzed via chromatically-resolved and full-spectrum PL decay measurements. The second study analyzes the size dependence of the bimodal PL decay, where the amplitude of the nanosecond and microsecond decay are related to nanocrystal size, while the third project analyzes the temperature and microstructure dependencies of the PL from SiNC solids. After an indepth look at the PL from SiNCs, this report examines preliminary results of SiNC and silver nanocrystal self-assembly. When compared to metal and metal chalcogenide nanoparticles, there is a dearth of literature on the self-assembly of SiNCs. To understand these phenomena, we analyze the size dependent ability of SiNCs to form a ‘superlattice’ and compare this with silver nanocrystals. Although the results on self-assembly are still somewhat preliminary, it appears that factors such as SiNC concentration and size dispersity play a key role in SiNC self-assembly, while suggesting intrinsic differences between the self-assembly of SiNCs and silver nanocrystals. Finally, at the end of this dissertation, a corollary project is presented on the computational analysis of fluorescent silver nanoclusters (AgNCs). Due to their small size and non-toxic nature, AgNCs are an ideal fluorophore for biological systems, yet there is a limited understanding of their photophysics, which is the focus of this part of the dissertation.
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    Synthesis and Utilization of Si6H12 and Si6X12 (X = Cl, Br) for the Generation of Novel Silicon Materials
    (North Dakota State University, 2017) Frohlich, Matthew T.
    Cyclohexasilane (Si6H12) and its derivatives, Si6X12 (X = Cl, Br), have chemical and physical properties different from linear and branched polysilanes, thus creating interest in their use as starting materials for a variety of applications. The liquid nature and lower activation energy of Si6H12 give it advantages as a starting material for silicon based materials including quantum dots (SiQDs), nanorods (SiNRs) and nanowires (SiNWs), as well as novel processing methods such as roll to roll deposition of silicon thin films. The electronegative elements on Si6X12 create Lewis acid sites above and below the ring, giving it the ability to form novel salts and 1-dimensional stacked polymers. This work developed a new route toward Si6H12 and Si6Cl12 by focusing on the production of the precursor [Si6Cl142-] dianion salts and studying their physical and chemical properties. This thesis also describes the preparation of novel Si6X12 based materials.