Physical Sciences and Mathematics Commons^™

Influence Of Shelling Temperature And Time On The Optical And Structural Properties Of Cuins2/Zns Quantum Dots, Colette Robinson

Graduate Theses and Dissertations

CIS/ZnS core/shell QDs are an important class of nanomaterials for optoelectronic, photovoltaic and photoluminescence applications. They consist of lower toxicity materials than the prototypical II-VI Cd-based QDs and show long fluorescence lifetimes, which generates prospective in biological imaging applications. It is vital to develop reproducible synthetic methods for this new class of nanomaterials in order to maintain small sizes with high QYs. CIS core QDs have been shelled with ZnS at various temperatures from 90-210°C for reaction times ranging from 20-140 minutes to examine the role of thermodynamics and kinetics on the shell growth. Using HR-TEM and ICP-MS, it was …

Photochemistry Of A Series Of Weakly Coupled Dinuclear Ruthenium(Ii) Complexes, Latisha Michelle Puckett

Graduate Theses and Dissertations

An improved synthetic method was developed for symmetric ruthenium(II) polypyridine complexes with the form L2Ru(diphen)RuL2. The scope of the reaction was investigated in regards to the ligands, bridging ligands, and starting materials. Several ligands were successful in the synthesis, including 2,2’-bipyridine (bpy), 4,4’-dimethyl-2,2’-dipyridyl (dmb), 1,10-phenanthroline (phen), 4,7-diphenyl-1,10-phenanthroline (dpphen), and 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen). Ligands that did not react to form symmetric dimeric complexes were 2,2’-bipyrazine, bpz, and 2,2’-bipyrimidine, bpm.

Dpp, 2,3-bis(2-pyridyl)-pyrazine, effectively replaced diphen as the bridging ligand to produce (phen)2Ru(dpp)Ru(phen)24+. However, replacing the [Ru(CO)2Cl2]n with Ru(DMSO)4Cl2 did not prove successful. The newly developed synthesis was also applied to the synthesis of …

Synthesis Of Medicinally Relevant Thiazolyl Aryl Ketones Under Mild Conditions, Danielle M. Gardner

Health, Human Performance and Recreation Undergraduate Honors Theses

Purpose: The growing amount of clinical resistance observed in current antifungal drugs and in anti-HIV pharmaceuticals is a concern in the medical community. The purpose of this study is to develop a mild synthetic process for biomedically relevant thiazolyl aryl ketones that can be used to develop antifungal and anti-HIV drugs. We hypothesized that the proposed synthetic technique would be more efficient, produce fewer unwanted byproducts, and be more tolerant of functional groups than existing methods.

Methods: Prior to each of the ketone reactions, the necessary salt was synthesized by mixing thiazole and 9-bromofluorene neat in a reaction tube heated …

Synthesis Of Palladium And Palladium-Copper Nanostructures As Electrocatalysts, Haibin Wu

Graduate Theses and Dissertations

Pd and its alloys are alternatives of Pt as promising catalysts and electrocatalysts for many reactions. Size controlled synthesis of nanoparticles remains a major research subject, since smaller size particles show better catalytic performance. In this work, we developed a modified chemical wet method to prepare Pd and Pd-Cu nanostructures with uniform small size. Different sizes and shapes of Pd nanostructures were successfully synthesized by using the two reducing agents (i.e., L-ascorbyl-6-palmitate or phenylphosphinic acid). The reducing agents play a role to control the final morphologies and sizes of particles. The use of L-ascorbyl-6-palmitate favors to form irregular branch shapes …

Surface Modification Of Noble Metal Nanostructures Toward Biomedical Applications, Samir V. Jenkins

Graduate Theses and Dissertations

Noble metal nanostructures have seen a steady increase in biomedical application over the last several decades; new diagnostic and therapeutic modalities are under intense investigation. Many of these applications are possible because of post-synthetic modifications to the particle surface. These modifications take a variety of forms and can significantly affect the pharmacokinetics of these particles. In this work, various surface modifications were investigated. Particle agglomeration, which occurs when particle surfaces remain in contact, can significantly affect the toxicity and efficacy of a nanomedicine. Darkfield microscopy and single-particle ICP-MS were developed as complementary methods to detect agglomeration in blood, with the …

Designing Fret Assays To Study Electrostatic Interactions Pertaining To The Binding Of Intrinsically Disordered Proteins, Ashley Ann Howard

Graduate Theses and Dissertations

Fibroblast growth factor receptor plays a major role in several biological processes. Without FGFR, a human cannot live. FGFR is involved in cell differentiation and wound healing. Of course, if FGFR signaling becomes unregulated, it causes severe distress in the body. Several cancers are contributed to high signaling levels, as well as developmental conditions like rickets and Kallmann’s syndrome. FGFR is thought to undergo an auto-inhibition (or self-regulatory) process in order to try to facilitate regulation. The exact method of this inhibition is currently unknown, but is proposed to involve the unstructured acid box region of FGFR. We developed a …

Asymmetric Synthesis And Transition Metal-Catalyzed Cross-Coupling Arylations Of Selected Organolithiums, Barry Kyle Sharp

Graduate Theses and Dissertations

My former boss, Dr. Gawley, always loved to say, “The world is chiral” (à la Pasteur). From DNA and proteins to hands and feet, it is obviously true. Also, a wide variety of chemical products exist as single enantiomers. Advances in chemical technology have greatly accelerated asymmetric synthesis in the past quarter century, and namely, organolithiums, have been shown to provide a versatile route to chiral natural products and biologically active molecules. Versatility arises from the array of methods that produce a chiral organolithium. Dynamic thermodynamic resolution (DTR) is considered one of the most practical methods, but among the others …

Fret Study Of Ligand Binding And Exchange Kinetics On The Surface Of Cdse/Zns Quantum Dots, Randee Jean Mcbride

Graduate Theses and Dissertations

Quantum dots are a valuable tool in many research applications and commercial development. Their applications are far reaching and as such have become a topic of great interest. One of their greatest assets is the ability to utilize them as water soluble fluorescent labels. Rendering the nanocrystals water soluble can be accomplished in several ways, but one very popular method is by capping them with water-soluble multi-functional organic ligands. However, these ligands, when attached to the quantum dot surface, are labile and can be exchanged which can be problematic when using the quantum dots in research applications. This projects investigates …

In Vitro Microdialysis Sampling Collection Of Volatile Organic Compounds (Voc's), Dodecafluoropentane (Ddfp) And Isoflurane, Valerie Shannon Mckinney

Graduate Theses and Dissertations

Death by stroke occurs every four minutes to human beings. Strokes cause necrosis within the tissue of the brain due to deprivation of oxygen. Perfluorocarbons have the ability to transport oxygen to tissue and in return decrease cell death. Dodecafluoropentane (DDFP) is a volatile fluorocarbon and collection in vivo can be a challenge since this compound evaporates at room temperature. There is currently not an efficient collection method in vivo for compounds that are volatile. Without a method to collect DDFP it is impossible to be approved for clinical use since exact concentrations of the drug within the body will …

Fundamental Studies Of Magnetoconvective Forces And Density Gradients In A Microfluidic Environment, Adam James Kreidermacher

Graduate Theses and Dissertations

Magnetoconvection is a promising phenomenon for developing new electrochemical-based microfluidic flow devices with unique capabilities, such as easily switching flow direction and adjusting flow speeds and flow patterns as well as avoiding bubble formation. In order to develop these devices it is necessary to study the underlying forces. Four contributions toward fluid flow were considered. The first and foremost is the magnetohydrodynamic force, which is the magnetic component of the Lorentz force and governed by the right hand rule. It generates the majority of the convention, and is the most well-known. The second is the gravitational force, which causes convection …

Inertial Force-Driven Synthesis Of Near-Infrared Plasmonic Nanosphere Composites: Physicochemical Characterizations, Joseph Noel Batta-Mpouma

Graduate Theses and Dissertations

Near-infrared (NIR) responsive nanoparticles (NPs) like gold nanorods (GNRs) are important in biomedical fields because of their transparency for biological tissues. Although GNRs are sought after as contrast agents for theranostics in cancer studies, capping ligands like cetyltrimethylammonium bromide (CTAB) for the GNR synthesis are toxic for biological tissues. The need for an alternative to toxic GNRs is of interest to alleviate the problem.

This work aimed to optimize the synthesis of NIR responsive nanosphere composites (NSCs) by inertial force (g-force) using colloidal gold NPs as model, elucidate the mechanism for the NSC formation, and study their detailed physicochemical characteristics. …

Simulation In Algorithmic Self-Assembly, Jacob Hendricks

Graduate Theses and Dissertations

Winfree introduced a model of self-assembling systems called the abstract Tile Assembly Model (aTAM) where square tiles with glues on their edges attach spontaneously via matching glues to form complex structures. A generalization of the aTAM called the 2HAM (two-handed aTAM) not only allows for single tiles to bind, but also for "supertile" assemblies consisting of any number of tiles to attach. We consider a variety of models based on either the aTAM or the 2HAM. The underlying commonality of the work presented here is simulation. We introduce the polyTAM, where a tile system consists of a collection of polyomino …

Characterization Of Cellulase Enzyme Inhibitors Formed During The Chemical Pretreatments Of Rice Straw, Kalavathy Rajan

Graduate Theses and Dissertations

Production of fuels and chemicals from a renewable and inexpensive resource such as lignocellulosic biomass is a lucrative and sustainable option for the advanced biofuel and bio-based chemical platform. Agricultural residues constitute the bulk of potential feedstock available for cellulosic fuel production. On a global scale, rice straw is the largest source of agricultural residues and is therefore an ideal crop model for biomass deconstruction studies. Lignocellulosic biofuel production involves the processes of biomass conditioning, enzymatic saccharification, microbial fermentation and ethanol distillation, and one of the major factors affecting its techno-economic feasibility is the biomass recalcitrance to enzymatic saccharification. Preconditioning …

Distinguishing Macrophage Activation States By Mass Spectrometry, Matthias Manfred Knust

Graduate Theses and Dissertations

Macrophages are versatile and highly adaptive cells that are involved in a wide range of physiological processes including host defense, homeostasis or regeneration, as well as pathogenesis. They react to their microenvironment, assuming various roles based on chemical and/or physical cues, and can reversibly shift between these so-called activation states. Concurrently, the technique of immunohistochemistry is used to gain spatial information on activated macrophages on tissue sections. The aim of this work was to find mass spectral biomarkers that allow the differentiation of activation states, and establish conditions that can be used in imaging mass spectrometry (IMS) experiments to investigate …

Wave Profile For Anti-Force Waves With Maximum Possible Currents, M. Hemmati, R. Horn, W. P. Childs, A. K. Meredith

Journal of the Arkansas Academy of Science

In the theoretical investigation of the electrical breakdown of a gas, we apply a one-dimensional, steady state, constant velocity, three component fluid model and consider the electrons to be the main element in propagation of the wave. The electron gas temperature, and therefore the electron gas partial pressure, is considered to be large enough to provide the driving force. The wave is considered to have a shock front, followed by a thin dynamical transition region. Our set of electron fluid-dynamical equations consists of the equations of conservation of mass, momentum, and energy, plus the Poisson's equation. The set of equations …

Bond Length - Bond Valence Relationships For Carbon - Carbon And Carbon - Oxygen Bonds, C. Harris, F. D. Hardcastle

Journal of the Arkansas Academy of Science

In the present study, relationships are developed for determining bond orders (also referred to as bond valences or bond numbers) from published bond lengths for carbon-carbon (C-C) and carbon-oxygen (C-O) bonds. The relationships are based on Pauling’s empirical formula s = exp((Ro-R)/b)), where s is the bond order, R is the corresponding bond length, Ro is the unit valence bond length, and b is a fitting parameter. We use a recently derived relationship for the b parameter in terms of the bonding atoms’ published atomic orbital exponents. The resulting equations were checked against published x-ray diffraction (XRD) data for 176 …

Low-Level Mercury Causes Inappropriate Activation In T And B Lymphocytes In The Absence Of Antigen Stimulation, K. L. Weigand, J. L. Reno, B. M. Rowley

Journal of the Arkansas Academy of Science

The immune system primarily utilizes two cell types for adaptive immunity: T lymphocytes and B lymphocytes. T lymphocytes are activated when antigen presenting cells (APCs) present antigen to membrane-bound T cell receptors. B lymphocytes are activated when an antigen binds to receptors embedded in the plasma membrane. In both T and B cells this antigen binding crosslinks the receptor complexes and initiates the signal transduction cascade. These cascades frequently consist of a series of intracellular molecules becoming phosphorylated in a step-wise fashion. Once activated, these cells differentiate into effector cells that clear out the stimulating antigen. Mercury, which is a …