Diverse sociology theoretical constructs serve as the lens to examine the evolution of two popular symbols of US culture in the last 20 years: yellow ribbons displayed as decoration and awareness ribbons worn as personal accoutrement. This research was motivated by society's weakened state of "collective consciousness," whereby shared beliefs and values have declined and some have completely disappeared, and sought to determine whether symbols will survive in a culture without commitment to the social. Invoking Christopher Lasch's Culture of Narcissism, Jean Baudrillard's Simulacra and Simulation, David Riesman's theory of other-directedness from The Lonely Crowd, and Stjepan Mestrovic's Postemotional Society, this work examined the significance of public displays of ribbons (whether on animate or inanimate objects), theorized why certain diseases and social causes "earned" their awareness ribbons and others did not, and demonstrated that these ribbons have served as multivalent symbols to accommodate our culture in a postmodern world. These symbols have not maintained their unifying function and now serve at the whim of the individual participant or observer. Ultimately, the act of wearing or displaying awareness ribbons and yellow ribbons, like so many other symbols, has been severed from the idea and is a freefloating, simulacrum to be used in whatever mode our postmodern, postemotional society requires.

Diverse sociology theoretical constructs serve as the lens to examine the evolution of two popular symbols of US culture in the last 20 years: yellow ribbons displayed as decoration and awareness ribbons worn as personal accoutrement. This research was motivated by society's weakened state of "collective consciousness," whereby shared beliefs and values have declined and some have completely disappeared, and sought to determine whether symbols will survive in a culture without commitment to the social. Invoking Christopher Lasch's Culture of Narcissism, Jean Baudrillard's Simulacra and Simulation, David Riesman's theory of other-directedness from The Lonely Crowd, and Stjepan Mestrovic's Postemotional Society, this work examined the significance of public displays of ribbons (whether on animate or inanimate objects), theorized why certain diseases and social causes "earned" their awareness ribbons and others did not, and demonstrated that these ribbons have served as multivalent symbols to accommodate our culture in a postmodern world. These symbols have not maintained their unifying function and now serve at the whim of the individual participant or observer. Ultimately, the act of wearing or displaying awareness ribbons and yellow ribbons, like so many other symbols, has been severed from the idea and is a freefloating, simulacrum to be used in whatever mode our postmodern, postemotional society requires.

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Recent advances in experimental and computational methods have opened up new directions in graphene fundamental studies. In addition to understanding the basic properties of this material and its quasi-one dimensional structures, significant efforts are devoted to describing their long ranged dispersive interactions. Other two-dimensional materials, such as silicene, germanene, and transition metal dichalcogenides, are also being investigated aiming at finding complementary to graphene systems with other "wonder" properties. The focus of this work is to utilize first principles simulations methods to build our basic knowledge of structure-interaction relations in two-dimensional materials and design their properties. In particular, mechanical folding and extended defects in zigzag and armchair graphene nanoribbons can be used to modulate their electronic and spin polarization characteristics and achieve different stacking patterns. Our simulations concerning zigzag silicene nanoribbons show width-dependent antiferromagnetic-ferromagnetic transitions unlike the case of zigzag graphene nanoribbons, which are always antiferromagnetic. Heterostructures, build by stacking graphene, silicene, and MoS$_2$, are also investigated. It is found that hybridization alters the electronic properties of the individual layers and new flexural and breathing phonon modes display unique behaviors in the heterostructure compositions. Anchored to SiC substrate graphene nanoribbons are also proposed as possible systems to be used in graphene electronics. Our findings are of importance not only for fundamental science, but they could also be used for future experimental developments.

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There has been an increasing appreciation of the role in which elasticity plays in soft matter. The understanding of many shapes and conformations of complex systems during equilibrium or non-equilibrium processes, ranging from the macroscopic to the microscopic, can be explained to a large extend by the theory of elasticity. We are motivated by older studies on how topology and shape couple in different novel systems and in this thesis, we present novel systems and tools for gaining fundamental insights into the wonderful world of geometry and soft matter. We first look at how defects, topology and geometry come together in the physics of thin membranes. Topological constraint plays a fundamental role on the morphology of crumpling membranes of genus zero and suggest how different fundamental shapes, such as platonic solids, can arise through a crumpling process. We present a way of classifying disclinations using a generalized “Casper-Klug” coordination number. We show that there exist symmetry breaking during the crumpling process, which can be described using Landau theory and that thin membranes preserve the memory of their defects. Next we consider the problem of the shapes of Bacillus spores and show how one can understand the folding patterns seen in bacterial coats by looking at the simplified problem of two concentric rings connected via springs. We show that when the two rings loses contact, rucks spontaneous formed leading to the complex folding patterns. We also develop a simple system of an extensible elastic on a spring support to study bifurcation in system that has adhesion. We explain the bifurcation diagram and show how it differs from the classical results. Lastly, we investigate the statistical mechanics of the Sadowsky ribbon in a similar spirit to the famous Kratky-Porod model. We present a detail theoretical and numerical calculations of the Sadowsky ribbon under the effect of external force and torsion. This model may be able to explain new and novel biopolymers ranging from actin, microtubules to rod-like viruses that lies outside the scope of WLC model. This concludes the thesis. / Physics

A combination of magnetic sensors with magnetic nanoparticles offers a promising approach for highly sensitive, simple, and rapid detection of cancer cells and biomolecules. The challenge facing the field of magnetic biosensing is the development of low-cost devices capable of superconducting quantum interference device (SQUID)-like field sensitivity at room temperature. In another area of interest, improving the sensitivity of existing electromagnetic field sensors for microwave energy sensing applications is an important and challenging task. In this dissertation, we have explored the excellent magnetoimpedance and microwave absorption responses of soft ferromagnetic amorphous ribbons and microwires for the development of high-performance magnetic biodetectors and microwave energy sensors. We have developed the effective approaches to improve the magnetoimpedance response of Co65Fe4Ni2Si15B14 amorphous ribbons by tuning their dimension and/or coating them with thin layers of CoFe2O4. Coating amorphous and crystalline CoFe2O4 films on the ribbon surface have opposite impacts on the magnetoimpedance response. Pulsed laser deposition (PLD) is shown to be a novel in-situ annealing and coating method for improving the magnetoimpedance response of the soft ferromagnetic amorphous ribbons for advanced sensor applications. The magnetoimpedance responses are also enhanced in multi-microwire systems relative to their single microwires. We have introduced a new method of combining the magnetoresistance (MR), magnetoreactance (MX), and magnetoimpedance (MI) effects of a soft ferromagnetic amorphous ribbon to develop an integrated biosensor with enhanced sensitivity and tunable frequency. While existing MI biosensors have limited sensitivities, we show that by exploiting the MR and MX effects it is possible to improve the sensitivity of the biosensor by up to 50% and 100%, respectively. The MX-based approach shows the most sensitive detection of superparamagnetic (Fe3O4) nanoparticles at low concentrations, demonstrating a sensitivity level comparable to that of a SQUID-based biosensor. Unlike a SQUID, however, the proposed MX technique is cryogen-free and operates at room temperature, providing a promising avenue to the development of low-cost highly sensitive biosensors. We have further improved the detection sensitivity of the MI and MX biosensors by patterning the sensing (ribbon) surface with nano/micro-sized holes, using the etching or focused ion beam (FIB) technique. These biosensors have been successfully employed to detect and quantify various bioanalytes, such as Curcumin-type anticancer drugs, bovine serum albumen (BSA) proteins, and Lewis lung carcinoma (LLC) cancer cells that have taken up the surface-functionalized Fe3O4 nanoparticles. Since Fe3O4 nanoparticles are widely used as magnetic resonance imaging (MRI) contrast agents, our biosensing technique can also be used as a new, low-cost, fast and easy pre-detection method before MRI. Finally, we have developed a new method of using a soft ferromagnetic glass-coated amorphous microwire as a microwave absorber for fabrication of a fiber Bragg grating-based microwave energy sensor with improved sensitivity and less perturbation of the microwave field. As compared to a similar approach that uses gold to absorb electromagnetic radiation, the microwire yields a device with greater sensitivity (~10 times at f = 3.25 GHz) relative to the perturbation of the microwave field. A correlation between the magnetic softness and microwave absorption in the microwires has been established, paving the way to improve the performance of the microwave energy sensor by tailoring their soft magnetic properties.

The structural, electronic, magnetic, magnetocaloric, and transport properties of doped Ni-Mn-(In, Sn) based Heusler alloys were studied using neutron diffraction, x-ray diffraction (XRD), differential scanning calorimetry (DSC), high field magnetization, specific heat, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and hydrostatic pressure measurements. The adiabatic temperature change (∆Tad) by a direct method and through thermomagnetic measurements in magnetic fields up to 14 T has been performed for these alloys. Also the mixed effect of pressure and magnetic field on the transition temperature of these alloys are discussed. In order to develop new magnetocaloric and multifunctional materials, the synthesis and characterization of Heusler alloys in reduced dimensions, i.e., ribbons and thin films has been performed. In addition, the structural, magnetic, and magnetocaloric properties of Ni-based binary alloys were investigated, including saturation magnetization and Curie temperature (TC) for the possible applications in self controlled magnetic hyperthermia applications.

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