Nanoscience and Nanotechnology Commons^™

Hierarchical Cell Fluid Extracellular Matrix Interaction In Cell Microenvironment, Soham Ghosh

Open Access Dissertations

Hierarchical structural interactions between components of cell microenvironment, the extracellular matrix (ECM), cytoplasm, nucleus and fluid, are important phenomena that decide cell level physiological process and tissue engineering applications. One of those tissue engineering modalities is freezing of biomaterials, important in a wide variety of biomedical applications including cryopreservation and cryosurgeries. In order to design these applications, freezing-induced changes of the cells and tissues and corresponding biophysical mechanisms need to be well understood. Although the effects of freezing on cells in suspension have been extensively studied, the intracellular mechanics of cells embedded in the extracellular matrix (ECM) during freezing are …

Dynamic Control Of Plasmonic Resonances With Graphene Based Nanostructures, Naresh Kumar Emani

Open Access Dissertations

Light incident on a metallic structure excites collective oscillations of electrons termed as plasmons. These plasmons are useful in control and manipulation of information in nanoscale dimensions and at high operating frequencies. Hence, the field of plasmonics opens up the possibility of developing nanoscale optoelectronic circuitry for computing and sensing applications. One of the challenges in this effort is the lack of tunable plasmonic resonance. Currently, the resonant wavelength of plasmonic structure is fixed by the material and structural parameters. Post-fabrication dynamic control of a plasmonic resonance is rather limited.^ In this thesis we explore the combination of optoelectrical properties …

Structural Characterization Of Multimetallic Nanoparticles, Vineetha Mukundan

Open Access Dissertations

Bimetallic and trimetallic alloy nanoparticles have enhanced catalytic activities due to their unique structural properties. Using in situ time-resolved synchrotron based x-ray diffraction, we investigated the structural properties of nanoscale catalysts undergoing various heat treatments. Thermal treatment brings about changes in particle size, morphology, dispersion of metals on support, alloying, surface electronic properties, etc. First, the mechanisms of coalescence and grain growth in PtNiCo nanoparticles supported on planar silica on silicon were examined in detail in the temperature range 400-900°C. The sintering process in PtNiCo nanoparticles was found to be accompanied by lattice contraction and L1₀chemical ordering. …

Advanced Iii-V / Si Nano-Scale Transistors And Contacts: Modeling And Analysis, Seung Hyun Park

Open Access Dissertations

The exponential miniaturization of Si CMOS technology has been a key to the electronics revolution. However, the continuous downscaling of the gate length becomes the biggest challenge to maintain higher speed, lower power, and better electrostatic integrity for each following generation. Hence, novel devices and better channel materials than Si are considered to improve the metal-oxide-semiconductor field-effect transistors (MOSFETs) device performance. III-V compound semiconductors and multi-gate structures are being considered as promising candidates in the next CMOS technology. III-V and Si nano-scale transistors in different architectures are investigated (1) to compare the performance between InGaAs of III-V compound semiconductors and …

Development Of A Static Bioactive Stent Prototype And Dynamic Aneurysm-On-A-Chip(Tm) Model For The Treatment Of Aneurysms, Lisa M. Reece

Open Access Dissertations

Aneurysms are pockets of blood that collect outside blood vessel walls forming dilatations and leaving arterial walls very prone to rupture. Current treatments include: (1) clipping, and (2) coil embolization, including stent-assisted coiling. While these procedures can be effective, it would be advantageous to design a biologically active stent, modified with magnetic stent coatings, allowing cells to be manipulated to heal the arterial lining. Further, velocity, pressure, and wall shear stresses aid in the disease development of aneurysmal growth, but the shear force mechanisms effecting wound closure is elusive. Due to these factors, there is a definite need to cultivate …

Silica Nanoparticles As Vehicles For Therapy Delivery In Neurological Injury, Desiree Schenk

Open Access Dissertations

Acrolein, a very reactive aldehyde, is a culprit in the biochemical cascade after primary, mechanical spinal cord injury (SCI), which leads to the destruction of tissue initially unharmed, referred to as "secondary injury". Additionally, in models of multiple sclerosis (MS) and some clinical research, acrolein levels are significantly increased. This aldehyde overwhelms the natural anti-oxidant system, reacts freely with proteins, and releases during lipid peroxidation (LPO), effectively regenerating its self. Due to its ability to make more copies of itself in the presence of tissue via lipid peroxidation, researchers believe that acrolein plays a role in the increased destruction of …

Optical Spectroscopy And Langmuir Probe Diagnostics Of Microwave Plasma In Synthesis Of Graphene-Based Nanomaterials, Alfredo D. Tuesta

Open Access Dissertations

Along with the revolutionary discovery and development of carbon nanostructures, such as carbon nanotubes and graphitic sheets, has arrived the potential for their application in the fields of medicine, bioscience and engineering due to their exceptional structural, thermal and electrical properties. As roll-to-roll plasma deposition systems begin to provide means for large scale production of these nanodevices, a detailed understanding of the environment responsible for their synthesis is imperative in order to more accurately design and control the growth of carbon nanodevices. To date, the understanding of the chemistry and kinetics that govern the synthesis of carbon nanodevices is only …

Design And Analysis Of Solar Cells By Coupled Electrical - Optical Simulation, Xufeng Wang

Open Access Dissertations

Careful electrical design and optical design are both crucial for achieving high-efficiency solar cells. It is common to link these two aspects serially; the optical design is first done to minimize reflection and maximize light trapping, and then the resulting optical generation rate is input to the electrical simulation. For very high efficiency solar cells that approach the Shockley-Queisser limit, however, electrical and optical transports are tightly coupled in both directions. Photons generated by radiative recombination can be reabsorbed to create additional electron-hole pairs (so-called photon recycling), which decreases losses. A variety of novel photon management schemes are currently being …

Role Of Group Ii Metabotropic Glutamate Receptor Subtype 2 (Mglur2) In Appetitive And Consummatory Aspects Of Ethanol Reinforcement, Kyle Allyson Windisch

Open Access Dissertations

Background: Group II metabotropic glutamate receptors (mGluR2/3) are predominately presynaptically located G_i/o coupled receptors that are highly expressed in the cortex, nucleus accumbens, amygdala, and hippocampus. Previous studies suggest that group II mGluRs are involved in regulating ethanol (EtOH) consumption and seeking following extinction (Backstrom and Hyytia, 2005; Kufahl, et al., 2011). The sipper tube model, which allows for procedural separation of seeking and consumption, was used to further clarify the role of mGluR2/3 in EtOH-seeking and consumption. The non-selective group II mGluR agonist LY379268 (LY37) and selective mGluR2 positive allosteric modulator (PAM) BINA were used to determine the …

Nano-Modification For High Performance Cement Composites With Cellulose Nanocrystals And Carbon Nanotubes, Yizheng Cao

Open Access Dissertations

One of the new engineering frontiers is the exploration of infrastructure materials with novel combinations of properties that break traditional paradigms. The goal of this study is to utilize two different nano-fibers, cellulose nanocrystals (CNCs) and carbon nanotubes (CNTs) to modify the nanoscale structures of cement composites and thereby improve the performance at the macro-level. This study also evaluates the mechanism behind the modification, since fiber bridging, the most common reinforcing mechanism for fiber-reinforced composites, cannot be simply applied because CNCs are too short to bridge cracks in cement composites. ^ The mechanical tests show an increase in the flexural …

Nano-Engineered Polymers In Drug Delivery: Potential Approaches For Attenuation Of Secondary Injury After Spinal Cord Trauma, Wen Gao

Open Access Dissertations

Secondary injury elicits a complex series of pathophysiological events after the primary spinal cord trauma and even after its implantation treatment for neural functional recovery. These secondary injuries include an up-regulation of glial cells associated reactive oxygen species, nitrogen species, and reactive astrogliosis, and they can result in various levels of cellular and tissue damage. The inhibition of them has been proved to lead to functional recovery of the spinal cord. In this study, we concentrated on developing polymers and nano-techniques based drug delivery strategies to eliminate these secondary injuries. ^ To maintain and improve the performance of the implants …

Nanogap Device: Fabrication And Applications, Jun Hyun Han

Dissertations (1934 -)

A nanogap device as a platform for nanoscale electronic devices is presented. Integrated nanostructures on the platform have been used to functionalize the nanogap for biosensor and molecular electronics. Nanogap devices have great potential as a tool for investigating physical phenomena at the nanoscale in nanotechnology. In this dissertation, a laterally self-aligned nanogap device is presented and its feasibility is demonstrated with a nano ZnO dot light emitting diode (LED) and the growth of a metallic sharp tip forming a subnanometer gap suitable for single molecule attachment.

For realizing a nanoscale device, a resolution of patterning is critical, and many …

Transport And Optical Properties Of Low-Dimensional Complex Systems, Andrii Iurov

Dissertations, Theses, and Capstone Projects

Over the last five years of my research work, I, my research was mainly concerned with certain crucial tunneling, transport and optical properties of novel low-dimensional graphitic and carbon-based materials as well as topological insulators. Both single-electron and many-body problems were addressed. We investigated the Dirac electrons transmission through a potential barrier in the presence of circularly polarized light. An anomalous photon-assisted enhanced transmission is predicted and explained in a comparison with the well-known Klein paradox. It is demonstrated that the perfect transmission for nearly-head-on collision in an infinite graphene is suppressed in gapped dressed states of electrons, which is …

Control Of Light-Matter Interaction Via Dispersion Engineering, Harish Natarajan Swaha Krishnamoorthy

Dissertations, Theses, and Capstone Projects

This thesis describes the design, fabrication and characterization of certain nanostructures to engineer light-matter interaction. These materials have peculiar dispersion properties owing to their structural design, which is exploited to control spontaneous emission properties of emitters such as quantum dots and dye molecules. We will discuss two classes of materials based on the size of their unit cell compared to the wavelength of the electromagnetic radiation they interact with. The first class are hyperbolic metamaterials (HMM) composed of alternate layers of a metal and a dielectric of thicknesses much smaller than the wave- length. Using a HMM composed of silver …

Manipulation Of Light In Plasmonic Nano-Structures, Rehab Kotb Abd-Allah

Theses and Dissertations

Manipulating light at nano-scale is usually shadowed by the diffraction limit. Recently, plasmonics have emerged as a new technology that enables confining light at nano-scale. Using plasmonic structures, photonic devices can be shrunk from the micro-scale to the nano-scale. In this thesis, a novel structure to a plasmonic nano-filter is introduced and analyzed. The proposed nano-resonator has low loss, compact size and good sensing characteristics. A closed form model to the filter behavior is developed. The model is extracted from the waveguide physical parameters and provides a physical insight into the structure of the filter. An analytical model to the …

In-Situ Afm Force Curve Investigations On Layered Structures Of Au(111)-Ionic Liquid Interfaces And Temperature Dependence, Xiao Zhang, Yun-Xin Zhong, Jia-Wei Yan, Bing-Wei Mao

Journal of Electrochemistry

By utilizing in-situ AFM force curve measurements systematic investigations have been carried out on Au(111)-ionic liquid interface in BMIPF₆ and OMIPF₆ of imidazolium-based ionic liquids with different lengths of alkyl side chains. The temperature dependence of the number, thickness and stability of the layered structures of each system are studied by performing AFM force curve measurements at potentials far negative of the PZC. The layered structures at Au (111)/BMIPF₆ interface are composed of two charged interior layers and two neutral exterior layers at -1.0 V, while those at Au (111)/OMIPF₆ interface only one charged interior layer …

Room Temperature Ionic Liquid Templated Meso-Macroporous Material By Self-Assembled Giant Gold Nanoparticles And Its Enhancement On The Direct Electrochemistry Of Cytochrome C, Pei Li, Dong-Ping Zhan, Yuan-Hua Shao

Journal of Electrochemistry

Room temperature ionic liquid (RTIL) is used as a soft-template to organize a meso-macroporous material constructed by self-assembled giant gold nanoparticles which are capped by L-cysteine. First, L-cysteine capped gold nanoparticles can self-assembly to form nanowires and sub-micrometer spherical giant particles due to the static interaction and/or the condensation reaction between the carboxyl and amino groups at the outer terminal of the ligand. Second, the spherical assembled particles can form a quasi-solid gel when grinding with a hydrophobic RTIL, 1-octyl-3-metyllimidazolium hexafluorophosphate. Finally, when the composite gel is coated on a glassy carbon electrode and then polarized by using cyclic voltammetry …

Electrochemical And Surface Enhanced Raman Spectroscopic Studies Of Benzimidazole On Nickel Electrode, Ping-Jie Wei, Ya-Xian Yuan, Min-Min Xu, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

By measuring cyclic voltammograms and polarization curves, the inhibition effects of benzimidazole (BMIH) concentration in acetonitrile system on a nickel electrode were investigated. It was found that the oxidation and the corrosion potentials shifted positively, and the oxidation current decreased with the increase in the concentration of BIMH. Potential dependent adsorption and film formation behavior of BMIH on the nickel electrode were investigated by in situ SERS spectroscopy. With the potential moving from negative direction to positive direction, the complexes made of BIMH and nickel were formed, preventing the nickel electrode from corrosion. In addition, the 0.001 mol·L^-1 of …

Synthesis Of Silver Nanoparticles Supported On Graphene Quantum Dots For Oxygen Reduction Reaction, Jian Ju, Wei Chen

Journal of Electrochemistry

Silver-based catalysts have been extensively investigated as the platinum substituted catalysts due to their high catalytic efficiency, low cost and long-term durability. In this study, the surfactant-free silver nanoparticles supported on graphene quantum dots were synthesized through a facile approach without addition of any other protecting ligands and reducing agents. The “surface-clean” silver nanoparticles had remarkable electrocatalytic performance towards oxygen reduction reaction (ORR) with the most efficient four-electron transfer process. Compared with commercial Pt/C catalyst, the hybrid nanoparticles showed comparable catalytic performance for ORR but much higher tolerance to methanol. Such silver nanoparticles supported on graphene quantum dots may have …

A Sensitive And Label-Free Electrochemical Aptasensor Based On Signal Amplification Of Carbon Nanotubes, Chun-Yan Deng, Hui-Min Fan, Juan Xiang, Yuan-Jian Li

Journal of Electrochemistry

A label-free electrochemical sensing electrode for highly sensitive detection of adenosine was constructed based on the signal amplification of carbon nanotubes (CNTs). The change in the interfacial feature of the modified electrode was characterized by electrochemical impedance spectroscopy. Using [Ru(NH₃)₆]³⁺ as the signaling moiety, adenosine with concentrations as low as 0.027 nmol·L^-1 can be selectively detected. Additionally, the fabrication of this present aptasensor was simple, time-saving and cost-effective. Compared with other reported aptasensors, the proposed aptasensor had advantages of excellent sensitivity, selectivity and simplicity, which plays a potential role in development of aptasensor.