Session B7: Undergraduate Research/SPS II

Theoretical Study of NaCl and LiCl Clusters

This research is a Quantum Mechanical study of molecular clusters that examines the chemical properties of small Na$_{\mathrm{n}}$Cl$_{\mathrm{n}}$ and Li$_{\mathrm{n}}$Cl$_{\mathrm{n}}$ clusters (n $=$ 2 - 20). The potentially important role of these molecular species in biochemical and medicinal processes is well known. This work applies the hybrid ab initio methods to derive the different alkali-halide (M$_{\mathrm{n}}$H$_{\mathrm{n}})$ geometries. Of particular interest is the competition between hexagonal ring geometries and rock salt structures. Electronic energies, rotational constants, dipole moments, and vibrational frequencies for these geometries are calculated. Magic numbers for cluster stability are identified and are related to the property of cluster compactness. Mapping of the singlet, triplet, and quintet, potential energy surfaces is performed. Calculations were performed to examine the interactions of these clusters with some atoms and molecules of biological interest, including O, O2, and Fe. Potential design of new medicinal drugs is explored. We will also investigate model and material dependence of the results.   

Anisotropic Magnetic Nanostructures For Enhanced Hyperthermia

Magnetic nanoparticles assisted hyperthermia is one of the most promising techniques for cancer treatment. By the use of magnetic nanoparticles in an external AC magnetic field, one can target a specific tumor location and deliver toxic doses of heat to the tumor area without damaging the surrounding healthy tissue. Magnetite is typically used in biomedical applications due to its biocompatibility, but the heating efficiency of the commonly used magnetite nanoparticles is not enough to obtain the best results in cancer treatment. Therefore, novel magnetic nanostructures are required in order to improve the heating efficiency. Recently, it has been proposed by different groups that it is possible to increase the heating efficiency of the nanoparticles by tuning their effective anisotropy. Considering this, we have synthesized high aspect ratio magnetic nanorods with increased effective anisotropy. A thorough structural and magnetic characterization has revealed high crystallinity and optimal magnetic properties of these nanorods. The hyperthermia response shows that by increasing the aspect ratio from 5 to 11, their heating efficiency is increased by 150{\%}. In addition, we have observed that a good alignment of the nanorods with the magnetic field ensures the best heating results. Hence, these nanorods appear to be promising candidates for cancer treatment with magnetic hyperthermia.   

Layer-by-Layer Assembly Onto Gold Nanoparticles of Various Size

This research focuses on the potential applications of coated gold nanoparticles in medicine. By coating gold nanoparticles in layers of polyelectrolytes, with a final layer of antibodies which targets chemicals uniquely exhibited by cancer cells, we eventually hope to selectively attach the nanoparticles to the cancer cells. The coated nanoparticles are assembled through layer-by-layer coulombic attraction due to the passive zeta potential of the particle and the charged nature of the polyelectrolytes. This poster will explore the potential usefulness of variously sized nanoparticles with various thickness of polyelectrolyte layers.   

Formation and Cytotoxicity of Nanoparticles and Nanocubes Prepared from Gold and Silver Salts

Photothermal therapy is the use of electromagnetic radiation as the treatment for medical conditions such as cancer. Noble metal nanoparticles and nanocubes are brought to an excited state with laser light and as a result they release vibrational energy in the form of heat, which can be used to kill targeted cancer cells. Wet chemistry gives the basics for the preparation of nanoparticles and nanocubes. Using HAuCl4, AgNO3, tri-sodium citrate and other chemicals, we were able to successfully create gold and silver nanoparticles and nanocubes. The goal is to make sure that 3T3 cells can survive in a nanoparticle or nanocube doped medium so that we can then observe their reaction to photothermal effects. Cell culture techniques were done to 3T3 cells to keep them alive before the testing of cytotoxicity. Photothermal effect refers to the way that our nanoparticles or nanocubes can be photoexcited to release enough heat to kill the cells. We used a UV-Vis spectrophotometer to ensure that the correct wavelength laser. Assuming that the cells will survive living in the doped medium, a medium that has had nanomaterials introduced into it, we will use a high powered laser to observe what the excitation does to the cells since the photothermal effect should result in dead cells.   

Implementation of Multiple Spectroscopic Techniques to Simultaneously Observe Native and Mutated Protein Unfolding

A protein's natural, correctly folded structure can determine the protein's ability to carry out its function. If the unfolding process of proteins can be observed, then the relative stability can be better understood between native and mutated proteins. A global picture of the unfolding process may be completed through the studies of strategically mutated proteins using tryptophan as a probe. Horse heart cytochrome c, a thoroughly studied, model protein was used in our investigation to explore this idea. Various spectroscopic techniques such as circular dichroism (CD), absorbance, and fluorescence were simultaneously applied while slowly unfolding our protein by increasing the concentration of a chemical denaturant, guanidine hydrochloride. This provided us information about the thermodynamic properties of the protein and several mutants which can then be interpreted to gain relative stability information among mutations. Efforts to utilize these techniques on native and mutated proteins in comparison to current scientific unfolding theories will be presented in this session.   

Transport of Motor Proteins along Microtubules: A Study by Optical Trapping Method and Analysis of Data

The cellular transportation is fundamental for cell function. Under this transportation, organelles bind to motor proteins. These proteins, then move along cellular microfilaments such as microtubules. The optical trapping technique is a method that allows us to monitor the movement of molecular motors along their tracks. In this method, motor proteins are absorbed by micro-sized beads. The beads are captured by the laser and placed close to the microfilaments. Consequently, the motor proteins bind to the track and move along them. This motion can be recorded and analyzed. In this work, we have analyzed many produced trajectories resulted from the motion of a single kinesin along microtubules. We present the design of the experiment, the method of recording and extracting data, as well as the factors that need to be considered to obtain accurate results. Finally, we calculated some of the physical properties resulted from kinesin movement in our experiment. Our outcomes are compatible with previously reported results.   

Olive Oil and its Potential Effects on Alzheimer's Disease

Alzheimer's disease is a neuro-degenerative brain disease that is responsible for affecting the lives of hundreds of thousands of people every year. There has been no evidence to suggest a cure for the disease and the only existing treatments have very low rates of success in trial patients. This is largely due to the fact that the brain is one of the most undiscovered parts of the human body. Brain chemistry is highly complex and responds to its environment in random and radical ways. My research includes testing the reactionary outcomes of combining compounds of olive oil with the 20 basic amino acids. Regions around the world with olive oil based diets show a direct correlation to lower rates of Alzheimer's. Testing few compounds of olive oil with chemicals already found in the brain may yield to a better understanding as to why that is. I took the compounds tyrosol, hydroxytyrosol, and oleocanthal, and combined them with the 20 basic amino acids and calculated the total energy of the new molecule. The molecules produced with acceptably low energy values will be the center of further research. These molecules could lead to truly understanding olive oil's effect on the brain, and ultimately, the cure or prevention of Alzheimer's disease.   

Optimization of Fe3O4 Nanoparticle Synthesis

Magnetic nanoparticles have been of great interest for the past several decades due to the increasing demands of technology as a direct result of device miniaturization. Additionally, they are interesting for biomedical applications, such as magnetic hyperthermia, because of their controllable size and shape, which can make them compatible with biological entities such as cells or viruses. In this study, iron oxide nanoparticles were synthesized through a thermal decomposition process. The original recipe was altered by changing the type and amounts of reagents used; the reaction time was also changed. Specifically, the amount of surfactants and solvent were altered, and the typical co-surfactant, 1,2-hexadecanediol was substituted by 1,2-tetradecanediol. Finally, a systematic reflux time study was conducted to determine the importance of reaction time to the synthetic process. Each sample was analyzed structurally via XRD to confirm the Fe3O4 phase and TEM to confirm their size. Several samples were also measured in a standard magnetometer to observe changes in their magnetic properties. Results from the systematic study will be presented here.   

Study of gold nanoparticle synthesis by synchrotron x-ray diffraction and fluorescence

Gold nanoparticles have a wide range of potential applications, including therapeutic agent delivery, catalysis, and electronics. Recently a new process of hollow nanoparticle synthesis was reported, the mechanism of which was hypothesized to involve electroless deposition around electrochemically evolved hydrogen bubbles. However, the growth mechanism still needs experimental evidence. We report investigation of this synthesis process using synchrotron x-ray diffraction and fluorescence measurements performed at beamline 2-ID-D of the Advanced Photon Source (APS). A series of gold nanoparticle samples with different synthesis time (50-1200 seconds) were deposited using a mixture electrolyte solution of Na$_{\mathrm{3}}$Au(SO$_{\mathrm{3}})_{\mathrm{2}}$ and H$_{\mathrm{4}}$N$_{\mathrm{2}}$NiO$_{\mathrm{6}}$S$_{\mathrm{2}}$ on anodic aluminum oxide (AAO) membranes. The 2D mapping of fluorescence intensity and comparison of x-ray diffraction peaks of the samples have provided valuable information on the growth mechanism.   

Softening and Hardening of a Micro-electro-mechanical systems (MEMS) Oscillator in a Nonlinear Regime

Micro-electro-mechanical systems or MEMS are used in a variety of today's technology and can be modeled using equations for nonlinear damped harmonic oscillators. Mathematical expressions have been formulated to determine resonance frequency shifts as a result of hardening and softening effects in MEMS devices. In this work we experimentally test the previous theoretical analysis of MEMS resonance frequency shifts in the nonlinear regime. Devices were put under low pressure at room temperature and swept through a range of frequencies with varying AC and DC excitation voltages to detect shifts in the resonant frequency. The MEMS device studied in this work exhibits a dominating spring softening effect due to the device's physical make-up. The softening effect becomes very dominant as the AC excitation is increased and the frequency shift of the resonance peak becomes quite significant at these larger excitations. Hardening effects are heavily dependent on mechanical factors that make up the MEMS devices. But they are not present in these MEMS devices. I will present our results along with the theoretical analysis of the Duffing oscillator model. This work was supported by NSF grant DMR-1461019 (REU) and DMR-1205891 (YL).   

A Simple Memristor Model for Circuit Simulations

This work describes the development of a model for the memristor, a novel nanoelectronic technology. The model was designed to replicate the real-world electrical characteristics of previously fabricated memristor devices, but was constructed with basic circuit elements using a free widely available circuit simulator, LT Spice. The modeled memrsistors were then used to construct a circuit that performs material implication. Material implication is a digital logic that can be used to perform all of the same basic functions as traditional CMOS gates, but with fewer nanoelectronic devices. This memristor-based digital logic could enable memristors' use in new paradigms of computer architecture with advantages in size, speed, and power over traditional computing circuits. Additionally, the ability to model the real-world electrical characteristics of memristors in a free circuit simulator using its standard library of elements could enable not only the development of memristor material implication, but also the development of a virtually unlimited array of other memristor-based circuits.   

Cosmic Reionization: An Analysis of Various Contributable Cosmological Factors.

According to the most accepted model of cosmology, the lambda-cdm model, the intergalactic medium (IGM) slowly becomes ionized after the period of recombination. This span of ionization, deemed the epoch of reionization, has proven to be a pertinent chapter to the narrative of our evolving universe. Star-forming galaxies have been accredited as the driving force behind reionization, however, recent results suggest that they cannot be the only cause of reionization. The purpose behind this work was to incorporate other cosmological phenomena to reduce the amount of radiation needed from star-forming galaxies, while still meeting the observational criteria of reionization.   

Alfven Wave Propagation in Young Stellar Systems

Young stellar systems have disks that are threaded by magnetic field lines with an hourglass geometry. These fields funnel ionizing cosmic rays (CRs) into the system. However, the effect is offset by magnetic mirroring. An previous analysis considered how the presence of magnetic turbulence moving outward from the disk would effect the propagation of cosmic-rays, and in turn, change the cosmic-ray ionization fraction occurring within the disk. This work indicated that turbulence reduces the overall flux of cosmic-rays at the disk, which has important consequences for both chemical processes and planet formation that occur within these environments. However, the analysis assumed ideal MHD condition in which the gas is perfectly coupled to the magnetic field. We explore here the validity of this assumption by solving the full equations governing the motion of both ions and neutral within the system.   

Theoretically Investigating the Nature of Spacetime- A grand definition of what clocks measure

Einstein's special theory of relativity established time as a dimension of reality, explaining physically the mathematical stipulations of Lorentz transformation equations that are required to keep the validity of Maxwell's equations of light and explain the null result of Michelson-Morley experiment. Our current understanding of time is relativistic, that is time is not absolute but runs differently depending on the frame of reference, yet this description uncovers so little about the fundamental reality of time. Using mathematical arguments derived from a simple thought experiment, both Lorentz transformation equations and Einstein's far reaching conclusions of his 1905 paper on the electrodynamics of moving bodies are obtained with arguments that suggest no prior knowledge of both Einstein and Lorentz works. This work attempts uncovering the fundamental nature of what clocks measure and a major implication of this is that the fourth dimension could just be a persistent illusion caused by the existence of space.