Physical Sciences and Mathematics Commons^™

Afci Quarterly Input – Unlv April Through June, 2005, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects, activities and objectives of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support.

Sensing Of Antipyretic Carboxylates By Simple Chromogenic Calix[4]Pyrroles, Ryuhei Nishiyabu, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

We present a simple, two- or three-step method for the synthesis of chromogenic octamethylcalix[4]pyrrole-based (OMCP) sensors for anions. Electrophilic aromatic substitution allows for converting the pyrrole moieties of OMCP into a dye. The formation of a sensor-anion complex results in partial charge transfer and a dramatic change in color. The absorption (UV-vis) and NMR titration experiments show that the chromogenic OMCPs sense anions administered as aqueous solutions, even at high ionic strength ( approximately 0.1 M NaCl), while displaying selectivity for pyrophosphate and carboxylate anions. The experiments with polyurethane sensor films show a strong response for aqueous carboxylates, such as …

Fluorescence-Dip Infrared Spectroscopy And Predissociation Dynamics Of Oh A (V=4) Radicals, Erika L. Derro, Ilana B. Pollack, Logan P. Dempsey, Margaret E. Greenslade, Yuxiu Lei, Dragana C. Radenovic, Marsha I. Lester

Chemistry

Fluorescence-dip infrared spectroscopy, an UV-IR double-resonance technique, is employed to characterize the line positions, linewidths, and corresponding lifetimes of highly predissociative rovibrational levels of the excited A  electronic state of the OH radical. Various lines of the 4←2 overtone transition in the excited A  state are observed, from which the rotational, centrifugal distortion, and spin-rotation constants for the A  (v = 4) state are determined, along with the vibrational frequency for the overtone transition. Homogeneous linewidths of 0.23–0.31 cm⁻¹ full width at half maximum are extracted from the line profiles, demonstrating that the N = …

The Effects Of Water On The Physical Properties Of Silica Aerogels, Shira G. Mandel

Honors Theses

The research found in this report focuses on varying the amount of water used in the fabrication of silica aerogels and characterizing the effect this has on their physical properties, such as density, thermal conductivity and transmittance. So far, the aerogels made with the "original" recipe have produced average density of 0.09 g/cm3 and thermal conductivity of 0.04 W/mK; these properties are not significantly altered as the amount of water used is increased or decreased. However, there is an observable trend in transmittance; as more water is added to the "standard" recipe, the resulting monoliths become more transparent and less …

The Design, Synthesis And Analysis Of High-Affinity Peptide-Peptoid Hybrid Ligands That Bind Evh1 Domains & The Synthesis Of 1-Substituted M-Terphenyls That Seve As N^C^C And O^C^C Ligands For Use In Cyclometallated Platinum Complexes, Eric J. Dimise

Honors Theses

Protein-ligand interactions are often at the center of cellular regulatory processes. The Enabled/ vasodilator Stimulated Phosphoprotein Homology 1 (EVH1) domain of the Enabled/ Vasodilator Stimulated Phosphoprotein (Ena/VASP) protein family has been linked to the regulation of the actin cytoskeleton through multiple protein-protein interactions via the recognition of polyproline amino acid sequences. Here, we examine the structural and physicochemical features of the EVH1 domain in an effort to design high affinity peptide-peptoid hybrid ligands that compete with EVH1's natural binding partners. & The unique photophysical properties of aryl, tridentate complexes of platinum have recently led to a surge in ligand design …

Inclusion Of Customized Quantum Dots Into Laponite Based Nanocomposites, Jennifer Rae Eliseo

Honors Theses

Quantum dot (QD) semiconductor nanocrystals offer unique electronic, magnetic, and optical properties, that can be used in advanced materials applications including optoelectronics, catalysis, sensing, and quantum computing. Tailoring of quantum dot surface coatings allows for control of self-assembly and facile inclusion into various host matrices. Querner and colleges have provided a novel synthetic route to graft aniline tetramer units onto quantum dots via a disulfide bridge. A key goal of our work has been the optimization of this synthesis for inclusion of functionalized QDs within Laponite/polyaniline nanoscaffolds. Uv/visible and fluorescence spectroscopy were used to study frequency resonance energy transfer within …

Radiolytic Damage To Freeze-Dried Human Amniotic Membrane, Chester C. Deocaris, Lucille B. Abad, Erwin P. Enriquez, Zenaida M. De Guzman, Ann A. Aliganga, Marianne B. Tangonan, Mitos M. Tolentino, Luzviminda V. Ignacio, Custer C. Deocaris

Chemistry Faculty Publications

Radiation-sterilization at 25 and 35 kGy of freeze-dried human amniotic membranes caused degradative effects in the biologic dressing. The decrease in pH and increase in UV absorption showed that radiation may have caused possible radiolytic changes in this biomaterial. Total nitrogen content, tensile strength, and [H3]water-retention capacity of the irradiated membranes remained invariable. Molecular topography analysis by atomic force microscopy showed radiation-induced defrayment of the collagen fibers, the major structural protein in amnion.

Biologically Active Fluorescent Farnesol Analogs, Roman Shchepin, Razvan Dumitru, Kenneth W. Nickerson, Miranda Lund, Patrick Dussault

Patrick Dussault Publications

We describe ten polyene analogs of farnesol, typified by 3,7,11-trimethyl-2,4,6,8,10-dodecapentenaldehyde oxime, which preserve the length, cross-section, and approximate hydrophobicity of farnesol. Four of the ten display strong quorum- sensing activity in the human pathogen Candida albicans, with IC₅₀ values for inhibition of germ-tube formation as low as 10 μM. The polyenes display absorption maxima between 320 and 380 nm, with the extinction coefficients for the oximes approaching 100,000. All but two of the analogs are fluorescent, with excitation maxima varying over the range of 320–370 nm. Oxime anti-4, which can undergo fluorescence excitation at wavelengths beyond 400 …

1,12-Diferrocenyldodecane At 100 K, Danielle M. Bequeath, Richard L. Porter, Michael W. Lufaso, Timothy R. Wagner, Rachel L. Kusnic, Matthias Zeller, Larry S. Curtin

Chemistry Faculty Research and Scholarship

1,12-Diferrocenyldodecane, [Fe₂(C₅H₅)₂(C₂₂H₃₂)], was synthesized from ferrocene and 1,12-dodecanedioyl chloride, followed by Clemmensen reduction. The single-crystal structure was determined at 100 K by X-ray diffraction and the spectroscopic and cyclic voltammetric data of 1,12-diferrocenyldodecane and its precursor are reported.

Synthesis And Spectroscopic Characterization Of Manganese Doped Zinc Sulfide Quantum Dot Nanocrystals, Pedro A. Gonzalez Beerman

Dissertations

Zinc sulphide quantum dots were synthesized in aqueous media using sodium polyphosphate as the stabilizer. The nanoparticles were 2.5 ± 0.5 nm and 5.0 ± 0.5 nm diameter depending on the synthetic procedure employed and the amount of Mn doped varied from 0.003 to 0.32% (w/w). The nanoparticles were characterized by UV-Vis absorption, luminescence, EPR, near edge x-ray absorption fine structure (NEXAFS), and x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD), and transmission electron microscopy (TEM). These quantum dots show a strong emission at 590 nm due to the ⁴T₁ -⁶A₁ transition characteristic of Mn …

Photoinduced One-Electron Reduction Of Alkyl Halides By Dirhodium(Ii,Ii) Tetraformamidinates And A Related Complex With Visible Light, Dean Johnston

Chemistry Faculty Scholarship

Various substituted dirhodium tetraformamidinate complexes, Rh(2)(R-form)(4) (R = p-CF(3), p-Cl, p-OCH(3), m-OCH(3); form = N,N'-diphenylformamidinate), and the new complex Rh(2)(tpgu)(4) (tpgu = 1,2,3-triphenylguanidinate) have been investigated as potential agents for the photoremediation of saturated halogenated aliphatic compounds, RX (R = alkyl group). The synthesis and characterization of the complexes is reported, and the crystal structure of Rh(2)(tpgu)(4) is presented. The lowest energy transition of the complexes is observed at approximately 870 nm and the complexes react with alkyl chlorides and alkyl bromides under low energy irradiation (lambda(irr) > or = 795 nm), but not when kept in the dark. The metal-containing …

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 …

Synergy Between Nanocomposite Formation And Low Levels Of Bromine On Fire Retardancy In Polystyrenes, Grace Chigwada, Panchatapa Jash, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

An organically-modified clay has been prepared using ammonium salts which contain an oligomeric material consisting of vinylbenzyl chloride, styrene and dibromostyrene. The presence of dibromostyrene enhances the flame retardancy of polystyrene nanocomposites compared to both the virgin polymer and polystyrene nanocomposites prepared from non-halogen-containing organically-modified clays. The nanocomposites were prepared both by bulk polymerization and melt blending and they were evaluated by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry measurements. Bulk polymerization produced nanocomposites with reduced peak heat release rate, reduced total heat release and improved thermal stability. It is noteworthy that all these improvements were obtained …

Ionic Liquid As Catalysts In The Cycloaddition Of Co2 To Styrene Oxide In Supercritical And Subcritical States, Joy Mwalimu

Masters Theses

Supercritical fluids (SCFs) have fascinated researchers ever since the discovery of a critical temperature more than a century ago.¹ Initial studies focused mainly on the physical properties of supercritical phases.² However, their use as reaction media has sparked mainly during the last five to ten years.²

The coupling of CO₂ and Ionic Liquids (ILs) in the synthesis of cyclic carbonates comes from an increasing need for environmentally and toxicologically benign processes for the production of high-value compounds. In my research, CO₂ was utilized as both a replacement solvent and a C₁ feedstock in its …

Cu(I) Luminescence From The Tetranuclear Cu4s4 Cofactor Of A Synthetic 4-Helix Bundle, Olesya A. Kharenko, David C. Kennedy, Borries Demeler, Michael J. Maroney, Michael Y. Ogawa

Chemistry Faculty Publications

The addition of Cu(I) to the random-coil peptide, C16C19-GGY, produces a self-organized, metal-bridged 4-helix bundle which displays an intense room-temperature luminescence at 600 nm. Emission, UV, and CD titrations along with X-ray absorption studies indicate that the luminescent cofactor is likely a Cu4S4 cluster in which each Cu atom is bridged by the side chains of two cysteine residues and has terminal N/O ligation.

Acylpyrazolones: Synthesis, Self-Assembly And Lanthanide Metal Ion Separation, Jun Yang

Dissertations

The central hypothesis that nanoscale self-assemblies can provide excellent metal ion recognition has been substantiated by employing acylpyrazolones and trivalent lanthanide metal ions as model systems. Several novel acylpyrazolones and their amphiphilic analogs have been designed, synthesized, and characterized. Their lanthanide metal ion recognition efficacies have been demonstrated through baseline separations of a mixture of light, middle, and heavy lanthanide metal ions by employing them in the aqueous mobile phase of high performance liquid chromatography (HPLC) with octadecylsilanized silica (ODS) as the stationary phase. The complex separation mechanism is influenced by the structures of acylpyrazolone and amphiphilic moieties, and spontaneous …

Effects Of Surfactants On The Thermal And Fire Properties Of Poly(Methyl Methacrylate)/Clay Nanocomposites, Panchatapa Jash, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites of poly(methyl methacrylate) (PMMA) with layered silicates and with polyhedral oligosilsesquioxanes (POSS) were prepared by bulk polymerization. The thermal and fire stabilities of the various organically-modified clay and POSS nanocomposites were evaluated using both thermogravimetric analysis (TGA) and cone calorimetry. Thermogravimetric analysis is not a good criteria for evaluating nanocomposite formation but cone calorimetry can be. For montmorillonite systems, when more than 4% clay is present, the expected reduction in peak heat release rate is observed. For hectorite, a minimum of 6% clay concentration is required to achieve the same reduction in peak heat release rate. POSS has the …

Modeling Of Flexible Drug-Like Molecules : Qsar Of Gbr 12909 Analog Dat/Sert Selectivity, Kathleen Mary Gilbert

Dissertations

The dopamine reuptake inhibitor GBR 12909 and related dialkyl piperazine and piperidine analogs have been studied as agonist substitution therapies acting on the dopamine transporter (DAT) to treat cocaine addiction. Undesirable binding to the serotonin transporter (SERT) can vary greatly depending on the specific substituents on the molecule. This study uses Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices (CoMSIA) techniques to determine a stable and predictive model for DAT/SERT selectivity for a set of flexible GBR 12909 analogs.

Families of analogs were constructed from six pairs of naphthyl-substituted piperazine and piperidine templates identified by hierarchical clustering as …

Study On Synthesis Of M-Phenoxy Benzoic Acid By Electrolysis Oxidation Method, Wei Xu, Chong-Tao Zhao

Journal of Electrochemistry

The m-phenoxy benzoic acid was synthesized by oxidation m-phenoxy toluene using Cr(Ⅵ)as oxidation media, which was prepared by electrolysis oxidation of Cr(Ⅲ)in the electrochemical bath using Nafion 417 as a diaphragm, Pb-PbO_(2) as an anode and Pb as cathode. The effect factors on the electrochemical oxidation of Cr(Ⅲ)to Cr(Ⅵ)in this electrolysis were studied. Furthermore, the optimal conditions for electronic synthesis of m-phenoxy benzoic acid were also discussed.

Innovation In Molten Salt Electrochemistry, Di-Hua Wang, Zheng Chen

Journal of Electrochemistry

Recent research development in molten salt electrochemistry at the Electrochemical Research Centre of Wuhan University is briefly reviewed. Attention is first paid on the preparation of silicon and its binary alloys, as well as oxide based functional materials. In addition, the quartz sealed Ag/AgCl reference electrodes suitable for high temperature molten salts are described. Focus is also given to two types of metal based cavity electrodes that are capable of loading micrograms of oxide powders and hence allow fast and reproducible measurements for the electrochemical behaviour of the powders in molten salts. The article finishes by highlighting the concept of …

Fabrication Of Nano Capacitor And Its Electrical Properties, Ling Liu, Qin Zhou, Neng-Qin Jia, Zhi-Yu Jiang

Journal of Electrochemistry

A step-by-step assembling method was developed for preparing nano capacitors using anodic aluminum oxide (AAO) membrane as templates. The nano capacitor consisted of three parts: electrochemically polymerized PPy electrode/ el ectrochemically precipitated porous TiO_(2) separator / chemically polymerized PPy electrode, and demonstrated the charge/discharge behavior as a typical electrochemical supercapacitor with good cyclic ability.

A Preliminary Study Of Electrocrystallization Of Bismuth On Glassy Carbon, Min-Li Yang, Zhan-Jun Zhang

Journal of Electrochemistry

The electrocrystallization of bismuth on glassy carbon electrodes (GCEs) from nitrate solutions was studied by cyclic voltammetry and chronoamperometry. Cyclic voltammograms exhibit a crossover between the cathodic and anodic branches, characteristic of the formation of bismuth nuclei on GCEs, and show that the bismuth electrocrystallization on GCEs is a diffusion-controlled reaction. The current transients were analyzed with the Scharifker and the Heerman equations. With the increaseof Bi~(3+)concentration, the non-dimensional plots leaned to the theoretical curve for 3D instantaneous nucleation and growth. The overpotential dependence of nucleation and growth mechanism was also found. With the increase of overpotential, the non-dimensional curve …

The Synthesis, Characteristics And Performance Of Cnt Composites As Anodic Materials In Litium-Ion Battery, Quan-Feng Dong, Ming-Sen Zheng, Zhen-Cai Huang, Ming-Gang Jin, Ya-Ding Zhan, Zu-Geng Lin

Journal of Electrochemistry

As an anodic material for lithium ion battery the carbon nano-tube (CNT) and some compounds based on tin have ever been investigated intensively. The fruited progress has not been made yet, however. In this paper the composites of CNT and Sn/SnO_(2)were synthesized employing two methods and characterized by SEM and XRD. And the electrochemical performance of the composites was investigated.

Potential Fluctuations Of 7075 Aluminum Alloy Under Thin Electrolyte Layers, Su-Jing Chen

Journal of Electrochemistry

Lens tissues adsorbing 3.5% sodium chloride solution were used to simulate thin electrolyte layers. The 7075 aluminum alloy was immersed under the thin electrolyte layers for 0, 4, 6, 8 and 12 h respectively. Then the fluctuations of natural-corrosion potentials of the alloy were monitored. The fluctuations of natural-corrosion potential were observed rather small in the initial corrosion stages after 6h immersion, and the positive peaks of potential appeared. However the amplitudes reached 20mV after 4h and 12h immersion. The RMS of natural-corrosion potentials decreased with corrosion time at first and then increased. It reached a minimum at 4 h. …

Ni-Mo-P Alloy By Electroless Deposition And Its Properties, Sen-Lin Wang

Journal of Electrochemistry

The electroless Ni-Mo-P alloy has been deposited from the alkaline bath containing boric acid as a buffer agent and sodium citrate as a complexing agent. The effect of deposition parameters, such as pH and concentration of (NH_(4))_(6)Mo_(7)O_(24)4H_(2)Oon the plating rate, the composition, the structure and the microhardness of the coating was examined. It was found that the presence of molybdenum has an inhibitory effect on the alloys deposition. As a consequence, the percentage of molybdenumin the Ni-Mo-P coatings never reaches high values, which was lower than 20 at%. It was also shown that the deposition condition affects the microhardness of …

Structure And Corrosion Electrochemical Properties Of Self-Assembled (3-Mercaptopropyl) Trimethoxysilane Films On Copper Electrode, Huangling Huangling, Ke-Fa Lin, Fang-Zu Yang, Shu-Kai Xu, Shao-Min Zhou

Journal of Electrochemistry

A self-assembled monolayer of (3-mercaptopropyl) trimethoxysilane(MPTS) was formed on a electrochemical polished copper surface electrode. The corrosion protection abilities of the monolayer were evaluated in 5% NaCl solution using electrochemical linear polarization. The effects of deposition time and silane concentration on corrosion of copper were also discussed. The surface structure of MPTS films was measured by FT-IR and SEM. It was found that the corrosion resistance of copper was reduced markedly owing to the MPTS monolayers formation on copper. The MPTS monolayer retarded the reduction of dissolved oxygen and inhibited the growth of copper oxide in the NaCl solution. FT-IR …

Selective Electroless Copper Plating Micro-Pattern On Ceramics Without Sensitisation And Activation, Zhen-Lin Xu

Journal of Electrochemistry

The purpose of this article is to provide a new technology of electroless copper plating without palladium activation steps. By combining the technology of laser micro-etching with the new copper-plating bath, copper plating on ceramics was obtained. The experimental results showed that the solution used for copper electroless plating was stable and the copper coating obtained was bright,dense with good electrical conductivity.The line definition was about 40 μm. The electroless Cu films deposited from this system were gentle and required simple operating conditions.

Using Electrodeposition To Fabricate Mould For Polymer Microfluidic Chip, Luo Yi

Journal of Electrochemistry

Many researches have been focused on polymer microfluidic chip in recent years and the mould plays an important role in its fabrication process. Using electrodepositingmethod to fabricate a metal mould for polymer microfluidic chip has been presented in this paper. An ultra-thick photoresist SU-8 was coated on a pretreated metal plate, after photolithography, nickel was electrodeposited in the patterned SU-8, then was removed the SU-8 to obtain a final metal mould. This methodreduces workload of electrodeposit largely. Applying counter current before deposit, adding additive to solution and vacuum anneal after demould have been used to improve the binding force between …

The Effect Of Oxidant On Structure And Properties Of Pan/Ptfe Conducting Composite Membrane, Chang-Yuan Tao

Journal of Electrochemistry

The PAn/PTFE conducting composite membrane was prepared by means of in-situ permeating chemical polymerization, with (NH_(4))_(2)S_(2)O_(8) and Na_(3)VO_(4) being used as an oxidant respectively.The polymerization-growth behavior of the aniline by using different oxidant was compared. In addition, the oxidant effect on the structure and properties of conducting composite membrane was discussed. The results of SEM micrographs, pore size distribution and electrochemical methods suggested that using either oxidants could also induce the product with small pore size and dense pore structure. Compared with (NH_(4))_(2)S_(2)O_(8), using Na_(3)VO_(4 ) as an oxidant would induce the polyaniline with denser polymers in the membrane pores, …

Preparation, Characterization And Electrochemical Properties Of Nano Tio_(2)-Cnt-Pt On Ti Substrate Complex Electrode, Dao-Bao Chu

Journal of Electrochemistry

The nanoTiO_(2)-CNT-Pt on Ti substrate complex electrodes were prepared from precursor of (Ti(OEt)_(4)) directly hydrolyzed and by cyclic voltammograms electroplating method . The XRD and SEM results showed that the nano TiO_(2) (anatase) particle sizes ranged 5~10 nm and the Pt nanoparticle (average size 9nm) dispersed uniformly on nanoTiO_(2)-CNT film surface. The electrocatalytic activity of Ti/nanoTiO_(2)-CNT-Pt electrode was investigated by cyclic voltammetry and chronopotentiogram. The results indicated that the Ti/nanoTiO_(2)-CNT-Pt electrode exhibited very high electrocatalytic activity and stability for the electro-oxidation of methanol at room temperature. When Pt loading was 0.32 mg/cm~(2), the oxidation peak current of methanol was 480 …