Physical Sciences and Mathematics Commons^™

Microcapsule Biosensors Based On Competitive Binding And Fluorescence Resonance Energy Transfer Assays, Swetha Chinnayelka

Doctoral Dissertations

Fluorescent sensing systems offer the potential for minimally invasive monitoring with implantable devices, but they require carrier technologies that provide suitable immobilization, accessibility, and biocompatibility while maintaining adequate response characteristics. Towards the development of this goal, a general design of a biosensor with the capability of detecting different metabolites was investigated. The approach is based on the encapsulation of a competitive binding assay in microcapsules and monitoring the changes in fluorescence resonance energy transfer (FRET) in the presence of analyte. To experimentally demonstrate this type of sensing system, glucose was chosen as the model target analyte. The design, fabrication, and …

Application Of Correlation-Gas Chromatography To Evaluate The Vaporization Enthalpy Of A Component In An Equilibrium Mixture, Manuel Temprado, James S. Chickos

James Chickos

No abstract provided.

Surface-Enhanced Raman Spectra Of Cytosine Adsorbed On A Roughened Gold Electrode, Yuan-Fei Wu, Jian-Feng Li, De-Yin Wu, Bin Ren, Zhong-Qun Tian

Journal of Electrochemistry

Cytosine adsorbed on a roughened gold electrode has been investigated by using electrochemical cyclic voltammetry and surface-enhanced Raman spectroscopy (SERS). The results indicate that cytosine was adsorbed on the Au electrode in a perpendicular orientation via the N3 position. As the maximum enhancement of ring breathing mode appears at negative potentials compared with other modes, both the electromagnetic enhancement and the charge transfer mechanism were considered to contribute to the SERS intensity. The binding interaction between cytosine and the gold electrode was weakened when the potential was negatively moved. The result also indicates that the SERS technique can be used …

Investigation, On The Accelerated Dissolution Of Metal Induced By Afm Tip Scratching And Suppressed By Inhibitors, Jun-E Qu, Xing-Peng Guo

Journal of Electrochemistry

The accelerated dissolution behavior of Cu-Ni alloy induced by AFM tip scratching and the inhibition effect of corrosion inhibitors were investigated. The results showedthat, with a tip loading of 750nN ,continuous scan for 30 min in a contact mode on 4×4 μm~(2) of copper-nickel alloy in 1.5mol/L NaCl and 0.01mol/L HCl could enhance the dissolution of the sample and produced pits on the scratched area. Adding inorganic inhibitors, sodium chromateand organic inhibitor dodecylamine, to the solution suppressed the dissolution of copper-nickel alloyinduced by tip scratching, respectively, by improving the surface passivationperformance of metal surface and forming adsorption films on copper-nickel …

The Application Of Astm C1202-93 On Evaluating The Performance Of Anti-Corrosion Of Concrete, Yuan Chen Yuan

Journal of Electrochemistry

The test of chloride ion penetration based on the standards of ASTM C1202-93 is applied to evaluate the anti-corrosion performance of concrete in this research. Concrete specimens were produced according to ACI 318-89 mixture proportioning design and the Desenfied Mixture Design Algorithm (DMDA) and were measured the 6-hour coulombs at the age of 91 days. Results show that w/b is not the factor influencing chloride penetration of ACI concrete, as the ion penetration of ACI specimens is all higher than 2 000 Coulombs and can even be poorer than 10 000 Coulombs. With a proper amount of pozzolanic material, the …

Cyclic Voltammetry And Surface Enhanced Raman Spectroscopy Of Dissociative Adsorption Of Ethanol On Pt-Ru Electrodes, Zhang Bin

Journal of Electrochemistry

The behaviors of dissociative adsorption of ethanol on roughened platinum-ruthenium electrode with high activity of SERS were studied by using cyclic voltammetry and in-situ surface enhanced Raman spectroscopy, surface enhanced Raman spectra of dissociative adsorption of ethanol on Pt electrode in acid was obtained for the first time. It is shown that the Pt-Ru could lower the over-potential of CO oxidation when compared to Pt electrode. The results show that the ethanol in acid medium can be self-dissociated at Pt-Ru electrode to produce CO, which discourage the further oxidation of ethanol, some information of Pt-C and Pt-C-Pt stretching vibration from …

Electrochemical Behavior And Determination Of Curcumin, Ping Wu, Wei Chen, Ya-Feng Zhang, Xin-Hua Lin

Journal of Electrochemistry

In 0.1mol/L phosphate buffer solution (pH 3.0), the voltammetry behaviors of curcumin at a glassy carbon electrode have been studied.One pair of current peaks of the voltammogram may be attributed to a reversible one-electron transfer of curcumin molecules at the glassy carbon electrode.A new method, the differential pulse voltammetry,for curcumin determination is described. The adsorptive potential of curcumin is (+0.8) V(vs. SCE),while its peak potential of curcumin is +0.386V(vs. SCE).The peak current is proportional to the concentration of curcumin over the rage of 1.0×10~(-8)mol/L ~2.5×10~(-7)mol/L.A detection limit of 4.0×10~(-9)mol/Lof curcumin can be estimated. The method is simple, rapid, sensitive and …

Analysis Of Liquid-Phase Chemical Detection Using Guided Shear Horizontal-Surface Acoustic Wave Sensors, Zhonghui Li, Yolanda Jones, Jeanne M. Hossenlopp, Richard Cernosek, Fabien Josse

Chemistry Faculty Research and Publications

Direct chemical sensing in liquid environments using polymer-guided shear horizontal surface acoustic wave sensor platforms on 36° rotated Y-cut LiTaO3 is investigated. Design considerations for optimizing these devices for liquid-phase detection are systematically explored. Two different sensor geometries are experimentally and theoretically analyzed. Dual delay line devices are used with a reference line coated with poly (methyl methacrylate) (PMMA) and a sensing line coated with a chemically sensitive polymer, which acts as both a guiding layer and a sensing layer or with a PMMA waveguide and a chemically sensitive polymer. Results show the three-layer model provides higher sensitivity than the …

The Electrochemical Separation Of Curium And Americium: Quaterly Report April - June, 2005, David W. Hatchett, Kenneth Czerwinski

Separations Campaign (TRP)

This research report outlines the current status and progress associated with the electrochemical separation of Curium and Americium.

Results

• We have completed the electrochemical investigation in of the Ce³⁺/Ce⁴⁺ redox couple and have determined the optimum experimental conditions.

• Computer modeling of the cerium using the JChess speciation-modeling program has been completed for the Ce redox couple. Traditional complexing ligands such as EDTA, oxalate, NTA, phosphate, acetate, and sulfate have been purchased and will be used to initiate the complexation and electrochemical characterization.

• Electrochemical investigations have continued on the Eu²⁺/Eu³⁺ redox …

Synthesis, Structural Studies And Desilylation Reactions Of Some N-2-(Trimethylsilyl)Ethyl-N-Nitrosocarbamates, Arpitha Thakkalapally, Vladimir Benin

Chemistry Faculty Publications

The present report describes the preparation and characterization of several N-2-(trimethylsilyl)ethyl-N-nitrosocarbamates, designed as precursors to thermally unstable secondary N-nitrosocarbamate anions via fluoride-assisted cleavage. X-ray structural studies demonstrate that the core N-nitrosocarbamate moiety has a nearly planar geometry, with an s-E orientation at the N–N bond. DFT calculations (B3LYP/6-31+G(d)) reproduce accurately the structural features of the title compounds and detailed conformational analysis at the same level of theory addresses the long-standing issue of preferred geometries for three classes of related structures: N-nitrosocarbamates, N-nitrosoureas and N-nitrosoamides. Desilylation studies demonstrate that both the …

Immobilization Of Fission Iodine By Reaction With A Fullerene Containing Carbon Compound And Insoluble Natural Organic Matrix: Quaterly Report January-March 2005, Spencer M. Steinberg

Separations Campaign (TRP)

We have continued experiments on the reaction of iodate with sphagnum peat moss. We have established that iodate added to a suspension of peat moss undergoes reduction and to a significant extent is incorporated in to the peat moss. We have confirmed the incorporation of iodine into the peat matrix using pyrolysis GC/MS. In addition, we have performed a scaled up pyrolysis using the preparative GC system that was described in a previous report. This instrument consisted of a packed column gas chromatograph (SRI 8010) with a TCD detector and injector valve equipped with a thermal desorber. Pyrolysis experiments were …

Improving Performance Characteristics Of Hyphenated Preconcentrator Gc Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: A "Gold Standard" For Sensor Development, Touradj Solouski

University of Maine Office of Research Administration: Grant Reports

Professor Touradj Solouki of the University of Maine at Orono is supported by the Analytical and Surface Chemistry Program to investigate cryofocusing of analytes in an Electrospray Ionization Fourier Transform Ion Cyclotron Resonance (ESI-FT-ICR) mass spectrometer. To overcome sensitivity problems of FT-ICR, Professor Solouki has added a pre-concentration (PC) gas chromatograph (GC) step to his setup. The goal of this Small Grant for Exploratory Research is to add an additional device: a cryofocuser after the GC. This is predicted to improve the detection limit by two orders of magnitude, and mass resolving power by a factor of 5-10. The PI …

Evaluation Of Fluorapatite As A Waste-Form Material: First Quarter Report, January 1 - March 31, 2005, Dennis W. Lindle, Oliver Hemmers

Separations Campaign (TRP)

Fluorapatite, fluorinated calcium phosphate, has been identified as a potential matrix for the entombment of the zirconium fluoride fission product waste stream from the proposed FLEX process. If the efficacy of fluorapatite-based waste-storage can be demonstrated, then new and potentially more-efficient options for handling and separating high-level wastes, based on fluoride-salt extraction, will become feasible. This proposal will develop a dual-path research project to develop a process to fabricate a synthetic fluorapatite waste form for the ZrF₄, FP waste stream, characterize the waste form, examine its performance under environmental conditions, and correlate the behavior of the waste form …

Fundamental Chemistry Of U And Pu In The Tbp-Dodecane-Nitric Acid System: Quaterly Report January - March, 2005, Kenneth Czerwinski, Cynthia-May Gong, Amber Wright

Separations Campaign (TRP)

The speciation of hexavalent U and tetravalent Pu will be examined in the TBP-dodecane-nitric acid systems. This topic is chosen based on data needs for separation modeling identified by the AFCI. Emphasis will be placed on studying the influence of nitrate and acetohydroxamic acid on U and Pu speciation as well as conditions where a third phase forms in the organic phase. The organic phase will be 30% TBP in dodecane. Equal volumes of aqueous and organic phase will be used. The speciation of the actinides in the aqueous and organic phase will be determined by a number of different …

Fundamental Chemistry Of U And Pu In The Tbp-Dodecane-Nitric Acid System: Quarterly Report January - March, 2006, Amber Wright, Frederic Poineau, Kenneth Czerwinski

Separations Campaign (TRP)

The speciation of hexavalent U and tetravalent Pu will be examined in the Tributylphosphate (TBP)-dodecane-nitric acid systems. This topic is chosen based on data needs for separation modeling identified by the AFCI. Emphasis will be placed on studying the influence of nitrate and acetohydroxamic acid on U and Pu speciation as well as conditions where a third phase forms in the organic phase. The organic phase will be 30% TBP in dodecane. Equal volumes of aqueous and organic phase will be used. The speciation of the actinides in the aqueous and organic phase will be determined by a number of …

Planar-To-Tubular Structural Transition In Boron Clusters: B20 As The Embryo Of Single-Walled Boron Nanotubes, Boggavarapu Kiran, Satya S. Bulusu, Hua-Jin Zhai, Soohaeng Yoo, Xiao Cheng Zeng, Lai-Sheng Wang

Xiao Cheng Zeng Publications

Experimental and computational simulations revealed that boron clusters, which favor planar (2D) structures up to 18 atoms, prefer 3D structures beginning at 20 atoms. Using global optimization methods, we found that the B₂₀ neutral cluster has a double-ring tubular structure with a diameter of 5.2 Å. For the B₂₀^- anion, the tubular structure is shown to be isoenergetic to 2D structures, which were observed and confirmed by photoelectron spectroscopy. The 2D-to-3D structural transition observed at B₂₀, reminiscent of the ring-to-fullerene transition at C₂₀ in carbon clusters, suggests it may be considered as the embryo …

Immobilization Of Fission Iodine By Reaction With A Fullerene Containing Carbon Compound And Insoluble Natural Organic Matrix: Quaterly Report October-December 2004, Spencer M. Steinberg

Separations Campaign (TRP)

We have conducted a large number of experiments to determine the possible reaction of iodate with sphagnum peat moss. These experiments indicate that the natural organic material reacts with iodate resulting in the formation of organically bound iodine and/or iodide in solution.

In the last quarter, we have conducted a number of experiments at various pHs and several temperatures (70oC, 60oC and 40oC). The reaction of iodate with peat follows pseudo first-order kinetics, although the reaction rate does appear to decrease significantly with reaction time. As noted in a previous report organically bound iodine appears to go through a maximum …

Measurement Of The Vaporization Enthalpy Of Complex Mixtures By Correlation-Gas Chromatography. The Vaporization Enthalpy Of Rp-1, Jp-7, And Jp-8 Rocket And Jet Fuels At T = 298.15 K, James S. Chickos, Hui Zhao

James Chickos

No abstract provided.

Modifications Of Human Βa1/Βa3-Crystallins Include S-Methylation, Glutathiolation, And Truncation, Veniamin N. Lapko, Ronald Cerny, David L. Smith, Jean B. Smith

Ronald Cerny Publications

Disulfide bonding of lens crystallins contributes to the aggregation and insolubilization of these proteins that leads to cataract. A high concentration of reduced glutathione is believed to be key in preventing oxidation of crystallin sulfhydryls to form disulfide bonds. This protective role is decreased in aged lenses because of lower glutathione levels, especially in the nucleus. We recently found that human [1]-crystallins undergo S-methylation at exposed cysteine residues, a reaction that may prevent disulfide bonding. We report here that βA1/A3-crystallins are also methylated at specific cysteine residues and are the most heavily methylated of the human lens crystallins. Among the …

Immobilization Of Fission Iodine By Reaction With A Fullerene Containing Carbon Compound And Insoluble Natural Matrix, Spencer M. Steinberg, Gary Cerefice, David W. Emerson

Separations Campaign (TRP)

The recovery of iodine released during the processing of used nuclear fuel poses a significant challenge to the transmutation of nuclear waste. Iodine-129, a long-lived fission product formed by both commercial nuclear power generation and nuclear weapons production, is released when reprocessing nuclear fuel. Since iodine can be concentrated in the human thyroid, any uncontrolled release of iodine may result in an increased rate of thyroid cancer in the exposed population. For this reason, recovery of iodine is important for implementing any nuclear transmutation strategy.

The stability of the association of iodine with FCC and NOM products are studied. Product …

Development Of Fluorapatite As A Waste Form: Final Report #280204-1, Boris E. Burakov

Separations Campaign (TRP)

In the framework of Agreement #280204 (first year) it was necessary to review methods of apatite synthesis; identify optimal procedure of precursor preparation; obtain and study first fluorapatite samples. Although, some apatite-based ceramics were successfully synthesized using co-precipitated precursors and sintering method, there are still a lot of uncertainties related to optimal apatite doping with different radionuclides and non-radioactive elements. It is necessary to provide complete incorporation of waste elements into apatite crystalline structure avoiding formation of separate phases of radionuclides. Also, it is important to note that real waste streams might contain radionuclides with essentially different chemical features such …

Electrochemical Separation Of Curium And Americium, David W. Hatchett, Kenneth Czerwinski

Separations Campaign (TRP)

The objective of this project is to use electrochemical techniques to develop a thermodynamic understanding of actinide and lanthanide species in aqueous solution and use this data to effectively separate species with very similar chemical properties. In consultation with our DOE collaborator, electrochemical methods and materials will be evaluated and used to exploit the thermodynamic differences between similar chemical species enhancing our ability to selectively target and sequester individual species from mixtures.

The following were specific goals for this year:

• To develop a fundamental understanding of the thermodynamic properties of actinide and lanthanide species such as Cm, Am, Ce, Nd, …

Fundamental Chemistry Of U And Pu In The Tbp-Dodecane-Nitric Acid System: Quarterly Report, Kenneth Czerwinski, Cynthia-May Gong, Amber Wright

Separations Campaign (TRP)

The speciation of hexavalent U and tetravalent Pu will be examined in the TBPdodecane- nitric acid systems. This topic is chosen based on data needs for separation modeling identified by the AFCI. Emphasis will be placed on studying the influence of nitrate and acetohydroxamic acid on U and Pu speciation as well as conditions where a third phase forms in the organic phase. The organic phase will be 30 % TBP in dodecane. Equal volumes of aqueous and organic phase will be used. The speciation of the actinides in the aqueous and organic phase will be determined by a number …

Fundamental Chemistry Of U And Pu In The Tbp-Dodecane-Nitric Acid System, Kenneth Czerwinski, Byron Bennett

Separations Campaign (TRP)

The research objectives of this project are as follows:

• To determine the influence of nitrate on the speciation of U and Pu in the TBP-dodecane-nitric acid system. The aqueous and organic speciation of U and Pu are examined as a function of the nitric acid concentration, nitrate concentration (by the addition of NaNO₃), actinide ion concentration, temperature, and time.
• To determine the speciation of U and Pu with AHA in the presence and absence of TBP-dodecane organic phase. The aqueous and organic speciation of U and Pu are evaluated as a function of AHA concentration, metal ion concentration, …

Anion And Cation-Yield Spectroscopy Of Core-Excited Sf6, Maria Novella Piancastelli, Wayne C. Stolte, Renaud Guillemin, A. Wolska, M. M. Sant'anna, Dennis W. Lindle

Chemistry and Biochemistry Faculty Research

We report an extensive study on total and partial-ion-yield spectroscopy around both the S 2p and F 1s thresholds in SF₆. All positive and negative single-ion channels have been measured. Below the F 1s threshold we detect a large variation in relative intensity of the resonant structures according to the specific channel monitored, indicating selective fragmentation. Above threshold, at variance with previous cases described by us, we detect high-intensity structures related to shape resonances not only in the cation channels but also for the anions. We discuss the applicability and limits of a model we …

Fragmentation Dynamics Of H2s Following S 2p Photoexcitation, Renaud Guillemin, S-W Yu, Wayne C. Stolte, Dennis W. Lindle

Chemistry and Biochemistry Faculty Research

The fragmentation dynamics of core-excited H₂S has been studied by means of partial anion and cation yield measurements around the S L_2,3-subshell ionization thresholds. All detectable ionic fragments are reported, and significant differences between partial ion yields are observed. Possible dissociation pathways are discussed by comparison to previous studies of electron spectra.

Near-Edge X-Ray Absorption Fine Structure Study Of Ion-Beam-Induced Phase Transformation In Gd2(Ti1-Yzry)2o7, Ponnusamy Nachimuthu, S. Thevuthasan, V. Shutthanandan, E. M. Adams, W. J. Weber, B. D. Begg, D. K. Shuh, Dennis W. Lindle, Eric M. Gullikson, Rupert C. Perera

Chemistry and Biochemistry Faculty Research

The structural and electronic properties of Gd₂(Ti_1−yZr_y)₂O₇ (y=0–1) pyrochlores following a 2.0-MeV Au²⁺ ion-beam irradiation (~5.0 X 10¹⁴ Au²⁺/cm²) have been investigated by Ti 2p and O 1s near-edge x-ray absorption fine structure (NEXAFS). The irradiation of Gd₂(Ti_1−yZr_y)₂O₇ leads to the phase transformation from the ordered pyrochlore structure (Fd3m) to the defect fluorite structure (Fm3m) regardless of Zr concentration. Irradiated Gd₂(Ti_{1−y …}

Elucidation Of The Mass Spectral Fragmentation Pathways Of Cyclic Hepatopeptides Microcystins, Paloma Muniz Ortea

Theses

The most frequently found cyanobacterial toxins in blooms from fresh and brackish waters are the cyclic peptide microcystins (MCs) and nodularin family. These toxins cause fatal poisonings of agricultural livestock, wild animals, birds and fish on a worldwide basis. The involvement of these toxins in human health problems has also been inferred in several countries and their presence in drinking water sources is of interest to the drinking water industry.

One of the biggest problems in the analysis of MCs is the lack of commercially available standards to be used for the identification and characterisation of these cyanobacterial toxins. One …

Exploring Marine Biotoxins Using Analytical Techniques Based On Mass Spectrometry, Mónica Fernández Amandi

Theses

The impact of phycotoxins on human and animal health is of important concern for worldwide authorities and the scientific community. Domoic acid (DA) is a neurotoxin produced by phytoplankton {Pseudonitzchia spp.). It enters the food chain through the consumption of shellfish that feed on toxic diatoms. DA has been responsible for several outbreaks affecting humans and animals all around the world. Yessotoxin (YTX) is produced by dinoflagellate species {Protoceratiuni reticulatum) which are globally distributed. Its toxicity is low when ingested orally. However, the co-extraction of YTX with diarrhetic shellfish poisoning (DSP) toxins, derives false positives when the mouse bioassay is …

Characterization Of Ionic, Dipolar And Molecular Mobility In Polymer Systems, Zhenrong Guo

Dissertations, Theses, and Masters Projects

Changes in the ionic and dipolar molecular mobility in a polymer system are the basis for the changes in the dielectric mechanical properties of polymer materials. Frequency Dependent Dielectric Measurements (FDEMS) and Ion Time-of-Flight (ITOF) are two important techniques to investigate ionic and dipolar molecular mobility in polymer systems. The results can be related to the macro- and molecular dielectric, electrical and dynamic properties of polymeric materials. The combination of these two methods provides a full view of electric, dielectric and dynamic behavior for the systems as they undergo chemical and/or physical changes during polymerization crystallization, vitrification, and/or phase separation.;The …