Physical Sciences and Mathematics Commons^™

Controlled Release Ot Methvl Salicvlate In Chitosanpoli[N-Isopropvlacrvlamide] Semi-Interpenetrating Networks, Ma. Assunta C. Cuyegkeng, Terence G. Henares

Chemistry Faculty Publications

A semi-interpenetrating network (semi-IPN) was produced by polymerizing Nisopropylacrylamide (NIP AAm) in the presence of chitosan and cross-linking agent, ethylene glycol dimethacrylate (EGDMA). The resulting material did not swell as much as poly(N-isopropylacrylamide) (piPAAm), but still showed temperature- and pHresponsiveness. Swelling and differential scanning calorimetry (DSC) experiments showed that the lower critical solution temperature (LCST) of the material was at 31 °C. The semiIPN was swollen below 30 °C but started to collapse at this temperature. This is in the same range as the LCST of carrageenan-piPAAm semi-IPN. The chitosan-piPAAm semi-IPN was in a collapsed state and reached maximum swelling …

High Performance Computing Instrumentation And Research Productivity In U.S. Universities, Linh B. Ngo, Amy W. Apon, Stanley Ahalt, Vijay Dantuluri, Constantin Gurdgiev, Moez Limayem, Michael Stealey

Linh B Ngo

This paper studies the relationship between investments in High-Performance Computing (HPC) instrumentation and research competitiveness. Measures of institutional HPC investment are computed from data that is readily available from the Top 500 list, a list that has been published twice a year since 1993 that lists the fastest 500 computers in the world at that time. Institutions that are studied include US doctoral-granting institutions that fall into the very high or high research rankings according to the Carnegie Foundation classifications and additional institutions that have had entries in the Top 500 list. Research competitiveness is derived from federal funding data, …

Corrosion Behavior Of Copper Thin Films In Organic Hf-Containing Cleaning Solution For Semiconductor Applications, Nabil George Mistkawi, Makarem A. Hussein, Malgorzata Ziomek-Moroz, Shankar B. Rananavare

Chemistry Faculty Publications and Presentations

The corrosion behavior of electrochemically deposited copper thin films in deaerated and non-deaerated commercial cleaning solutions containing HF was investigated. Potentiodynamic polarization experiments were carried out to determine active, active–passive, passive, and transpassive regions. Corrosion rates were calculated from Tafel slopes. The addition of hydrogen peroxide to the solution and its influence on corrosion was also investigated by employing inductively coupled plasma-mass spectroscopy (ICP-MS) and X-ray photoelectron spectroscopy (XPS). The ICP-MS and potentiodynamic methods yielded comparable Cu dissolution rates. Surface analysis using atomic force microscopy and scanning electron microscopy, performed before and after the cleaning solution treatment, did not reveal …

Search For Gas Giants Around Late-M Dwarfs, Rohit Deshpande

Electronic Theses and Dissertations

We carried out a near-infrared radial velocity search for Jupiter-mass planets around 36 late M dwarfs. This survey was the first of its kind undertaken to monitor radial velocity variability of these faint dwarfs. For this unique survey we employed the 10-m Keck II on Mauna Kea in Hawaii. With a resolution of 20,000 on the near-infrared spectrograph, NIRSPEC, we monitored these stars over four epochs in 2007. In addition to the measurement of relative radial velocity we established physical properties of these stars. The physical properties of M dwarfs we determined included the identification of neutral atomic lines, the …

Automated Interpretation Of The Tandem Mass Spectra Of Peptides Using Artificial Neural Networks, Timothy Patrick Manning

Theses

The manual interpretation of mass spectra is a complex and time consuming task. The problem of manually interpreting this data is further exacerbated by the large numbers of mass spectra which can potentially be produced in a single proteoniics experiment. This shows the need for high throughput approaches to the interpretation of mass spectra. Existing automated approaches are however error prone due to the complexity of the task. Accordingly, this thesis discusses and evaluates the application of neural networks to improving the sensitivity, specificity and robustness of current approaches to the automated interpretation of such mass spectral data.

Several neural …

The Role And Significance Placed On Corporate Social Responsibility In The Hotel Industry In The South West Region Of Ireland., Shirley Millar

Theses

This research sets out to examine the concept of Corporate Social Responsibility in the context of the hotel industry, with a specific focus on Ireland and the South West Region. The study looked at the level of importance placed on CSR by both the hotel consumer and the hotel industry. The study also sought to determine the relevance of CSR as a source of competitive advantage

Interest in the practice of Corporate Social Responsibility (CSR) has become increasingly prominent in recent years. There has been a shift in practice from companies doing good to be seen to be doing good, …

The Potential For Gaseous Biofuels In Ireland, Darren Kenneally

Theses

According to the EU Renewables Directive 2009/28/EC, 20% of the energy across Europe needs to be renewable by 2020. This is inclusive of the energy utilised in the transport sector where 10% of this energy needs to be renewable. In order for Ireland to meet the targets set in the Renewables Directive various changes need to be applied. The utilisation of gaseous biofuels produced from the anaerobic digestion of various feedstocks will aid Ireland in meeting this directive.

In this study biodegradable municipal waste (BMW) and energy crops are analysed as potential feedstocks for the production of biomethane. This biomethane …

Synthesis And Applications Of Ring Opening Metathesis Polymerization Based Functional Block Copolymers, Sanchita Biswas

Electronic Theses and Dissertations

Ring opening metathesis polymerization (ROMP) is established as one of the efficient controlled living polymerization methods which have various applications in polymer science and technology fields. The research presented in this dissertation addresses several applications of multifunctional well-defined norbornene-based block copolymers synthesized by ROMP using ruthenium-based Grubbs catalysts. These novel block copolymers were applied to stabilize maghemite nanoparticles, creating the superparamagnetic polymeric nanocomposites. The Jaggregation properties of the porphyrin dyes were improved via self-assembly with a customized norbornene polymer. Novel multimodal copolymer probes were synthesized for two-photon fluorescence integrin-targeted bioimaging. In Chapter 1 a brief overview of ROMP along with …

Species Composition And Spatiotemporal Pattern Of The Seed Bank And Vegetation In Native And Degraded Florida Rosemary Scrub, Jennifer J. Navarra

Electronic Theses and Dissertations

The soil seed bank plays a dynamic role in the regeneration of plant communities after natural and anthropogenic disturbance. In this thesis, I addressed how disturbances influence the vegetation and seed bank of Florida rosemary scrub. In Chapter One I evaluated changes in species composition and spatiotemporal pattern of the vegetation and seed bank along a gradient of disturbance. During the summers and winters of 2007-2009 percent ground cover and seed bank species composition were assessed among replicates of three vegetation types subjected to minimal, moderate, and extreme anthropogenic disturbance (native rosemary scrub, degraded scrub, and agriculturally improved pasture, respectively). …

Controlled Assembly And Electronic Transport Studies Of Solution Processed Carbon Nanotube Devices, Paul Stokes

Electronic Theses and Dissertations

Developing techniques for the parallel fabrication of Complementary Metal Oxide Semiconductor (CMOS) compatible single walled carbon nanotube (SWNT) electronic devices is of great importance for nanoelectronic applications. In this thesis, solution processed SWNTs in combination with AC dielectrophoresis (DEP) were utilized to fabricate CMOS compatible SWNT field effect transistors (FETs) and single electron transistors (SETs) with high yield and their detailed electronic transport properties were studied. Solution processing of SWNTs is attractive not only for the high throughput and parallel manufacturing of SWNT devices but also due to the ease of processing at room temperature, and compatibility with various substrates. …

New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir

Electronic Theses and Dissertations

The first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the experimental trends of negative characteristic temperature observed in QD lasers and clarify how the carrier distribution mechanisms inside and among the QDs affect the threshold …

Initial-Value Technique For Singularly Perturbed Two Point Boundary Value Problems Via Cubic Spline, Luis G. Negron

Electronic Theses and Dissertations

A recent method for solving singular perturbation problems is examined. It is designed for the applied mathematician or engineer who needs a convenient, useful tool that requires little preparation and can be readily implemented using little more than an industry-standard software package for spreadsheets. In this paper, we shall examine singularly perturbed two point boundary value problems with the boundary layer at one end point. An initial-value technique is used for its solution by replacing the problem with an asymptotically equivalent first order problem, which is, in turn, solved as an initial value problem by using cubic splines. Numerical examples …

Statistical Analysis Of Visible Absorption Spectra And Mass Spectra Obtained From Dyed Textile Fibers, Katie Margaret White

Electronic Theses and Dissertations

The National Academy of Sciences recently published a report which calls for improvements to the field of forensic science. Their report criticized many forensic disciplines for failure to establish rigorously-tested methods of comparison, and encouraged more research in these areas to establish limitations and assess error rates. This study applies chemometric and statistical methods to current and developing analytical techniques in fiber analysis. In addition to analysis of commercially available dyed textile fibers, two pairs of dyes are selected based for custom fabric dyeing on the similarities of their absorbance spectra and dye molecular structures. Visible absorption spectra for all …

The Development Of Scalable Pump Techniques For Gg Iag Fiber Lasers And Passive Athermalization Techniques For Solid State Laser, William Hageman

Electronic Theses and Dissertations

This dissertation consists of two parts: research pertaining to the development of scalable pump techniques for gain guided index-antiguided fiber lasers and research relating to the development of passive athermalization schemes for solid state lasers. The first section primarily details the development of a side pump scheme that allows for power scaling of gain-guided index anti-guided fibers. While these fibers have been demonstrated in past research, none have used a pump technology capable of pumping with the efficiencies, uniformity, and necessary length to allow for scaling of the fiber lasers to high output powers. The side pumped scheme developed in …

Near-Field Optical Interactions And Applications, David Haefner

Electronic Theses and Dissertations

The propagation symmetry of electromagnetic fields is affected by encounters with material systems. The effects of such interactions, for example, modifications of intensity, phase, polarization, angular spectrum, frequency, etc. can be used to obtain information about the material system. However, the propagation of electromagnetic waves imposes a fundamental limit to the length scales over which the material properties can be observed. In the realm of near-field optics, this limitation is overcome only through a secondary interaction that couples the high-spatial-frequency (but non-propagating) field components to propagating waves that can be detected. The available information depends intrinsically on this secondary interaction, …

Micro-Electro-Mechanical Systems (Mems) And Agile Lensing-Based Modules For Communications, Sensing And Signal Processing., Syed Reza

Electronic Theses and Dissertations

This dissertation proposes the use of the emerging Micro-Electro-Mechanical Systems (MEMS) and agile lensing optical device technologies to design novel and powerful signal conditioning and sensing modules for advanced applications in optical communications, physical parameter sensing and RF/optical signal processing. For example, these new module designs have experimentally demonstrated exceptional features such as stable loss broadband operations and high > 60 dB optical dynamic range signal filtering capabilities. The first part of the dissertation describes the design and demonstration of digital MEMS-based signal processing modules for communication systems and sensor networks using the TI DLP (Digital Light Processing) technology. Examples of …

Structural, Electronic, Vibrational And Thermodynamical Properties Of Surfaces And Nanoparticles, Handan Yildirim

Electronic Theses and Dissertations

The main focus of the thesis is to have better understanding of the atomic and electronic structures, vibrational dynamics and thermodynamics of metallic surfaces and bi-metallic nanoparticles (NPs) via a multi-scale simulational approach. The research presented here involves the study of the physical and chemical properties of metallic surfaces and NPs that are useful to determine their functionality in building novel materials. The study follows the 'bottom-up' approach for which the knowledge gathered at the scale of atoms and NPs serves as a base to build, at the macroscopic scale, materials with desired physical and chemical properties. We use a …

Picosecond Electron Diffraction From Molecules Aligned By Dissociation, Martin Centurion, Peter Reckenthaeler, Ferenc Krausz, Ernst E. Fill

Martin Centurion Publications

In gas electron diffraction an averaging over statistical directions of the molecules takes place. This results in diffraction patterns in the form of isotropic rings which yield information only on the radial distribution function displaying the inter-atomic distances. We demonstrate that by dissociating molecules with linearly polarized light the pattern becomes anisotropic. In the experiments the iodide C₂F₄I₂ is dissociated and molecular difference intensities and difference radial distribution curves are measured for directions parallel and perpendicular to the direction of polarization. With picosecond temporal resolution the curves clearly demonstrate transient anisotropy and its decay by …

Cobalt Nanoclusters On Metal-Supported Xe Monolayers: Influence Of The Substrate On Cluster Formation Kinetics And Magnetism, V. Sessi, K. Kuhnke, J. Zhang, Jan Honolka, Klaus Kern, Axel Enders, P. Bencok, S. Bornemann, J. Minár, Hubert Ebert

Axel Enders Publications

The growth dynamics of submonolayer coverages of cobalt during buffer-layer assisted growth on Ag(111) and Pt(111) substrates is investigated by variable temperature scanning tunneling microscopy in the temperature range between 80 and 150 K. It is found that attractive cluster-substrate interactions can govern the cluster formation on the Xe buffer layer if the Xe layer is sufficiently thin. The interpretation of the microscopy results is supported by x-ray magnetic circular dichroism data which monitor the effect of cluster-substrate interactions on the formation of magnetic moments and magnetic anisotropy of Co nanocluster during the different stages of growth. Ab initio calculations …

Magnetic Surface Nanostructures, Axel Enders, Ralph A. Skomski, Jan Honolka

Axel Enders Publications

Recent trends in the emerging field of surface-supported magnetic nanostructures are reviewed. Current strategies for nanostructure synthesis are summarized, followed by a predominantly theoretical description of magnetic phenomena in surface magnetic structures and a review of experimental research in this field. Emphasis is on Fe- or Co-based nanostructures in various low-dimensional geometries, which are studied as model systems to explore the effects of dimensionality, atomic coordination, chemical bonds, alloying and, most importantly, interactions with the supporting substrate on the magnetism. This review also includes a discussion of closely related systems, such as 3d element impurities integrated into organic networks, surface-supported …

Magnetic Susceptibility Of Nanoscale Kondo Systems, Ralph Skomski, R. Zhang, Parashu Kharel, Axel Enders, Sy_Hwang Liou, D. J. Sellmyer

Axel Enders Publications

The mesoscopic Kondo effect in metallic nanoparticles containing a magnetic impurity is investigated by model calculations. A Maxwell–Garnett approach is used to approximately determine the resistivity of doped nanoparticles in a matrix, and the magnetic susceptibility is estimated from the confinement of the conduction electrons. Conductivity measurements of nanoparticles embedded in a matrix are difficult to realize, because metallic matrices distort the Kondo cloud, whereas insulating or semiconducting matrices yield a very weak signal. By comparison, susceptibility measurements do not suffer from these shortcomings. The Kondo effect survives in nanoparticles even if the cluster size is much smaller than the …

Polarized Neutron Reflectometry Study Of The Magnetization Reversal Process In Yba2cu3o7 /La2/3ca1/3mno3 Superlattices Grown On Srtio3 Substrates, J. Hoppler, H. Fritzsche, V. K. Malik, J. Stahn, G. P. Cristiani, H.-U. Habermeier, M. Rössle, Jan Honolka, Axel Enders, C. Bernhard

Axel Enders Publications

Using polarized neutron reflectometry we investigated the reversal of the magnetization of a high-T_c superconductor/ferromagnet superlattice that consists of eight bilayers of YBa₂Cu₃O₇(25.6 nm) /La_2/3Ca_1/3MnO₃(25.6 nm) grown on a SrTiO3 substrate. The measurements were performed during a magnetization hysteresis loop at 5 K. We obtained evidence that the reversal in the vicinity of the coercive field proceeds via the switching of micrometer-sized magnetic domains that are considerably larger than the typical domains of La_2/3Ca_1/3MnO₃. Furthermore, these large magnetic domains …

Self-Assembly And Properties Of Nonmetalated Tetraphenyl-Porphyrin On Metal Substrates, Geoffrey Rojas, Xumin Chen, Cameron Bravo, Ji-Hyun Kim, Jae-Sung Kim, Jie Xiao, Peter A. Dowben, Yi Gao, Xiao Cheng Zeng, Wonyoung Choe, Axel Enders

Axel Enders Publications

The structure−electronic structure relationship of nonmetalated meso-tetraphenyl porphyrin (2H-TPP) on the (111) surfaces of Ag, Cu, and Au was studied with a combination of scanning tunneling microscopy, photoelectron spectroscopy, and density functional theory. We observe that the molecules form a 2D network on Ag(111), driven by attractive intermolecular interactions, while the surface migration barriers are comparatively small and the charge transfer to the adsorbed molecules is minimal. This is in contrast to a significant charge transfer observed in 2H-TPP/Cu(111), resulting in repulsive forces between the molecules that prevent molecular adlayer network formation. It is shown that the limiting factor in …

Vibrational Properties Of Ferroelectric Β-Vinylidene Fluoride Polymers And Oligomers, Serge M. Nakhmanson, Rafal Korlacki, J. Travis Johnston, Stephen Ducharme, Zhongxin Ge, James M. Takacs

Stephen Ducharme Publications

We utilize a plane-wave density-functional theory approach to investigate the vibrational properties of the all-trans ferroelectric phase of poly(vinylidene fluoride) (β-PVDF) showing that its stable state corresponds to the Ama2 structure with ordered dihedral tilting of the VDF monomers along the polymer chains. We then combine our theoretical analysis with IR spectroscopy to examine vibrations in oligomer crystals that are structurally related to the β-PVDF phase. We demonstrate that these materials—which can be grown in a highly crystalline form—exhibit IR activity similar to that of β-PVDF, making them an attractive choice for the studies of electroactive phenomena and phase transitions …

Digital Forensics And The Issues Of Identity, Andrew Jones, Thomas Martin

Research outputs pre 2011

The issue of what we consider to be the identity of a person has become increasingly complex as we have made ever greater use of the facilities and services that have been made available by developing technologies and the Internet. In the past people normally had one identity, while in the current environment it is acceptable to maintain separate ‘identities’ for different aspects of our on-line interactions. Proving beyond a reasonable doubt that an individual that is suspected of a crime that is based on the technologies that we increasingly rely on was the actual perpetrator has always been problematic. …

Evolving Group Strategies For Ipd, Philip Hingston

Research outputs pre 2011

The Iterated Prisoners Dilemma (IPD) is often used to model cooperation between self-interested agents. In an earlier study, we introduced a framework using IPD to study the effects of species-level competition on the evolution of cooperative behaviour. In this paper, we extend the previous work, using co-evolutionary simulations of interactions between species of IPD-playing agents to investigate how group strategies may evolve. We find that the ability to cooperate more with agents of the same species greatly increases the ferocity of competition between species.

A Novel Subspace Outlier Detection Approach In High Dimensional Data Sets, Jinsong Leng

Research outputs pre 2011

Many real applications are required to detect outliers in high dimensional data sets. The major difficulty of mining outliers lies on the fact that outliers are often embedded in subspaces. No efficient methods are available in general for subspace-based outlier detection. Most existing subspacebased outlier detection methods identify outliers by searching for abnormal sparse density units in subspaces. In this paper, we present a novel approach for finding outliers in the ‘interesting’ subspaces. The interesting subspaces are strongly correlated with `good' clusters. This approach aims to group the meaningful subspaces and then identify outliers in the projected subspaces. In doing …

A Wrapper-Based Feature Selection For Analysis Of Large Data Sets, Jinsong Leng, Craig Valli, Leisa Armstrong

Research outputs pre 2011

Knowledge discovery from large data sets using classic data mining techniques has been proved to be difficult due to large size in both dimension and samples. In real applications, data sets often consist of many noisy, redundant, and irrelevant features, resulting in degrading the classification accuracy and increasing the complexity exponentially. Due to the inherent nature, the analysis of the quality of data sets is difficult and very limited approaches about this issue can be found in the literature. This paper presents a novel method to investigate the quality and structure of data sets, i.e., how to analyze whether there …

Ignorant Experts: Computer And Network Security Support From Internet Service Providers, Patryk Szewczyk, Craig Valli

Research outputs pre 2011

The paper examines the advice and support provided by seven major Internet Service Providers in Australia through late 2009 and early 2010 in relation to computer and network security. Previous research has indicated that many end-users will attempt to utilise the support provided by Internet Service Providers as a simple and effective method by which to obtain key information in regards to computer security. This paper demonstrates that in many cases the individuals working at the help desk are either reluctant to provide IT security support or have insufficient skill to provide the correct information.

Behaviour Profiling On Mobile Devices, Fudong Li, Nathan Clarke, Maria Papadaki, Paul Dowland

Research outputs pre 2011

Over the last decade, the mobile device has become a ubiquitous tool within everyday life. Unfortunately, whilst the popularity of mobile devices has increased, a corresponding increase can also be identified in the threats being targeted towards these devices. Security countermeasures such as AV and firewalls are being deployed, however, the increasing sophistication of the attacks requires additional measures to be taken. This paper proposes a novel behaviour-based profiling technique that is able to build upon the weaknesses of current systems by developing a comprehensive multilevel approach to profiling. In support of this model, a series of experiments have been …