Chemistry Commons^™

Afci Quarterly Input – Unlv April 1 Through June 30, 2007, 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.

Potentiometric And Relaxometric Properties Of A Gadolinium-Based Mri Contrast Agent For Sensing Tissue Ph, Ferenc K. Kálmán, Mark Woods, Peter Caravan, Paul Jurek, Marga Spiller, Gyula Tircso, Róbert Király, Ernő Brücher, A. Dean Sherry

Chemistry Faculty Publications and Presentations

The pH-sensitive contrast agent, GdDOTA-4AmP (Gd1) has been successfully used to map tissue pH by MRI. Further studies now demonstrate that two distinct chemical forms of the complex can be prepared depending upon the pH at which Gd³⁺ is mixed with ligand 1. The desired pH-sensitive form of this complex, referred to here as a Type II complex, is obtained as the exclusive product only when the complexation reaction is performed above pH 8. At lower pH values, a second complex is formed that, by analogy with an intermediate formed during the preparation of GdDOTA, we tentatively assign …

Modification Of Carboplatin By Jurkat Cells, Anthony J. Di Pasqua, Jerry Goodisman, Deborah J. Kerwood, Bonnie B. Toms, James C. Dabrowiak

Chemistry - All Scholarship

Using [¹H,¹⁵N] heteronuclear single quantum coherance (HSQC) NMR and ¹⁵N-labeled carboplatin, 1, we show that Jurkat cells affect the rate of disappearance of the HSQC NMR peak in culture medium for this Pt²⁺ anticancer drug. The decay or disappearance rate constant for 1 in culture medium containing cells is k₁ = k_c [CO₃^{2 -}] + k_m + k_u N, where k_c is the rate constant for reaction of 1 with carbonate in the medium, k_m is the rate constant for reaction of 1 with all …

Stable Aqueous Nanoparticle Film Assemblies With Covalent And Charged Polymer Linking Networks, Lesley E. Russell, Anne A. Galyean, Sherilyn M. Notte, Michael C. Leopold

Chemistry Faculty Publications

The construction of highly stable and efficiently assembled multilayer films of purely water soluble gold nanoparticles is reported. Citrate-stabilized nanoparticles (CS-NPs) of average core diameter of 10 nm are used as templates for stabilization-based exchange reactions with thioctic acid to form more robust aqueous NPs that can be assembled into multilayer films. The thioctic acid stabilized nanoparticles (TAS-NPs) are networked via covalent and electrostatic linking systems, employing dithiols and the cationic polymer poly(l-lysine), respectively. Multilayer films of up to 150 nm in thickness are successfully grown at biological pH with no observable degradation of the NPs within the film. The …

A Series Of Vertically Integrated Nanotechnology Experiments For The Undergraduate Curriculum, Kevin W. Kittredge, Lesley E. Russell, Michael C. Leopold

Chemistry Faculty Publications

We have designed three nanotechnology experiments that are vertically integrated for an undergraduate chemistry curriculum. They are an evolving set of experiments for sequential courses in an undergraduate chemistry program. These experiments are designed to match the student's level of understanding for each particular course. The participating student is involved in a "research" project that progresses in both theory and experimental technique. Students benefit from these vertically integrated experiments by being involved in multiple facets of a simulated research project. This mimics a traditional research project under an advisor's supervision without the undesired drawback of an unknown outcome.

Metallopharmaceuticals As Photoactivatable Anticancer Drugs, Samar Moqadasi, Christine O'Connor, Denis O'Shea, Michael Devereux

Conference Papers

Target-based research (treating infected site only), directed towards the design and mechanism of action of metal-based anticancer complexes is expanding rapidly due to the selectivity and activity of such novel therapeutics. The photo activation of Ruthenium (II) complexes as therapeutic drugs has recently escalated as the complexes are suitable for photoactivation due to their well published photochemical and photophysical properties which in turn is the basis of photodynamic approaches to therapy.1-5 The aim of this study is to synthesise a series of metallo-complexes of which will be tested on tumour and non-tumour cell lines in the Radiation & Environmental Science …

Regulation Of Cell Diameter, For3p Localization, And Cell Symmetry By Fission Yeast Rho-Gap Rga4p, Maitreyi Das, David J. Wiley, Saskia Medina, Helen A. Vincent, Michelle D. Larrea, Andrea Oriolo, Fulvia Verde

Chemistry and Physics Faculty Articles

Control of cellular dimensions and cell symmetry are critical for development and differentiation. Here we provide evidence that the putative Rho-GAP Rga4p of Schizosaccharomyces pombe controls cellular dimensions. rga4Δ cells are wider in diameter and shorter in length, whereas Rga4p overexpression leads to reduced diameter of the growing cell tip. Consistent with a negative role in cell growth control, Rga4p protein localizes to the cell sides in a “corset” pattern, and to the nongrowing cell tips. Additionally, rga4Δ cells show an altered growth pattern similar to that observed in mutants of the formin homology protein For3p. Consistent with …

Fluctuating Two-State Light Harvesting In A Photosynthetic Membrane, Duohai Pan, Dehong Hu, Ruchuan Liu, Xiaohua Zeng, Samuel Kaplan, H. Peter Lu

Chemistry Faculty Publications

The mechanism by which light is converted into chemical energy in a natural photosynthetic system has drawn considerable research interest. Using fluorescence spectroscopy and microscopic imaging, we have observed fluctuating intermolecular protein fluorescence resonant energy transfers (FRET) among light-harvesting proteins I and II (LH1 and LH2) in bacterial photosynthetic membranes. Using two-channel, FRET, photon-counting detection and a novel, two-dimensional cross-correlation function amplitude-mapping analysis, we revealed fluorescence intensity and spectral fluctuations of donor (LH2) and acceptor (LH1) fluorescence involving FRET. Our results suggest that there are dynamic coupled and noncoupled states of the light-harvesting protein assemblies in photosynthetic membranes. The light-harvesting …

Structural Analysis Of Csos1a And The Protein Shell Of The Halothiobacillus Neapolitanus Carboxysome, Yingssu Tsai, Michael R. Sawaya, Gordon C. Cannon, Fei Cai, Eric B. Williams, Sabine Heinhorst, Cheryl A. Kerfeld, Todd O. Yeates

Faculty Publications

The carboxysome is a bacterial organelle that functions to enhance the efficiency of CO2 fixation by encapsulating the enzymes ribulose bisphosphate carboxylase/ oxygenase (RuBisCO) and carbonic anhydrase. The outer shell of the carboxysome is reminiscent of a viral capsid, being constructed from many copies of a few small proteins. Here we describe the structure of the shell protein CsoS1A from the chemoautotrophic bacterium Halothiobacillus neapolitanus. The CsoS1A protein forms hexameric units that pack tightly together to form a molecular layer, which is perforated by narrow pores. Sulfate ions, soaked into crystals of CsoS1A, are observed in the pores of the …

A Polymorph Of K₄Ge₄Se₁₀, Amitava Choudhury, Sabine Strobel, Peter K. Dorhout

Chemistry Faculty Research & Creative Works

A new monoclinic polymorph, ?-K4Ge4Se10 (tetra-potassium deca-selenidotetra-germanate), that crystallizes in space group P21/c has been isolated. The structure contains isolated super-tetra-hedral adamantane [Ge4Se10]^4- clusters identical to those in the known K4Ge4Se10 polymorph (P21/m), held together in in the crystal structure by ionic inter-action with the K⁺ ions. The adamantane unit, [Ge4Se10] ^4-, is formed by corner-sharing of four GeSe4 tetra-hedra, with average Ge -. Se distances of 2.378 and 2.281 Å for (Ge - Se)endo and (Ge - Se)exo, respectively. There are four crystallographically distinct K ⁺ ions in ?-K4Ge4Se10 having coordination numbers of 5, 7. and …

The Global Hepatic Transcriptional Response Of Male Fisher Rats To Dietary Aroclor 1254 Exposure, Trisha M. Basford

Dissertations

Dietary intake is a primary route for biomagnification of environmentally persistent polychlorinated biphenyls (PCBs) within humans and animals. Aroclor 1254, a mixture of PCBs, is associated with a variety of toxic responses including alterations in blood and lipid biochemistry and tumor promotion. Measurement of the transcriptional responses to low-level dietary exposure to A1254 has not been reported to date, and is important given the persistence of PCBs, and range of effects associated with exposure. The aims of this study were to characterize changes in rat hepatic global gene expression due to sub-acute and sub-chronic dietary exposure to A1254, and to …

Characterization Of The Catalytically Active Mn(Ii)-Loaded Arge-Encoded N-Acetyl-L-Ornithine Deacetylase From Escherichia Coli, Wade C. Mcgregor, Sabina I. Swierczek, Brian Bennett, Richard C. Holz

Physics Faculty Research and Publications

The catalytically competent Mn(II)-loaded form of the argE-encoded N-acetyl-l-ornithine deacetylase from Escherichia coli (ArgE) was characterized by kinetic, thermodynamic, and spectroscopic methods. Maximum N-acetyl-l-ornithine (NAO) hydrolytic activity was observed in the presence of one Mn(II) ion with k _cat and K _m values of 550 s⁻¹ and 0.8 mM, respectively, providing a catalytic efficiency (k _cat/K _m) of 6.9 × 10⁵ M⁻¹ s⁻¹. The ArgE dissociation constant (K _d) for Mn(II) was determined to be 0.18 μM, correlating well with a value obtained by isothermal titration …

Triplet Energy Studies Of Thiophene And Para-Phenylene Based Oligomers, Leandro A. Estrada, Victor A. Montes, Grigory Zyryanov, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

A series of conjugated materials based on oligomers of the para-phenylene type and oligothiophenes was prepared, and their phosphorescence spectra were recorded at 77 K using a pulsed flash-lamp as a light source and gated detection. The triplet energies of the oligomers were estimated and correlated with their chemical structure. It was found that simple changes in the building block sequence in the thiophene-containing oligomers allowed for tuning the triplet energy from 1.86 to 2.35 eV (530-670 nm). Hypsochromic shifts and little variation of the triplet energy were obtained with increasing length of the pi-system for thiophene end-capped oligomers, contrary …

Supramolecular Chemistry Approach To The Design Of A High-Resolution Sensor Array For Multianion Detection In Water, Manuel A. Palacios, Ryuhei Nishiyabu, Manuel Marquez, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

Reliable sensing of structurally similar anions in water is a difficult problem, and analytical tests and sensor devices for reliable sensing of multiple anions are very rare. This study describes a method for fabrication of simple colorimetric array-based assays for aqueous anion solutions, including complex analytes encountered in real-life applications. On the fundamental level, this method shows how the discriminatory capacity of sensor arrays utilizing pattern recognition operating in multianalyte environments may be dramatically improved by employing two key features. The synergy between the sensor and hydrogel host resembles the cooperative effects of an apoenzyme and cofactor: the host hydrogel …

Metallo-Cyclodextrin Complexes For The Separation Of Chiral Materials, Synthesis And Characterisation, Ciaran Francis Potter

Doctoral

The processes of separation and detection of chiral compounds are extremely important in the pharmaceutical industry. This study aims to investigate a safe and variable methods for the separation of the two enantiomers of the drug DOPA (Dihydroxyphenylalanine). L-DOPA is the most effective drug at present used to combat Parkinson’s disease while D-DOPA is inactive, thus for drug efficacy only the single biologically active enantiomer should be present in the formulation. In this work, cyclodextrins (CDS) were utilised fro their ability to act as a host for guest species, acting in the role as both a first and second sphere …

Ligand-Based Drug Design : I. Conformational Studies Of Gbr 12909 Analogs As Cocaine Antagonists; Ii. 3d-Qsar Studies Of Salvinorin A Analogs As Kappa Opioid Agonists, Deepangi Pandit

Dissertations

Ligand-based drug design (LBDD) techniques are applied when the structure of the receptor is unknown but when a series of compounds or ligands have been identified that show the biological activity of the interest. Generally, availability of a series of compounds with high activity, with no activity, and also with a range of intermediate activities for the desired biological target is required. It is common that structures of membrane-bound proteins (for example, monoamine transporter proteins and opioid receptor proteins) are unknown as these proteins are notoriously difficult to crystallize.

In Part I of this study, analogs of the flexible dopamine …

Albumin-Binding Paracest Agents, M. Meser Ali, Mark Woods, Eul Hyun Suh, Zoltan Kovacs, Gyula Tircsó, Piyu Zhao, Vikram D. Kodibagkar, A. Dean Sherry

Chemistry Faculty Publications and Presentations

Lanthanide complexes (Eu³⁺, Gd³⁺ and Yb³⁺) of two different 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid tetraamide derivatives containing two (2) and four (3) O-benzyl-L-serine amide substituents were synthesized and their chemical exchange saturation transfer (CEST) and relaxometric properties were examined in the presence and absence of human serum albumin (HSA). Both Eu2 and Eu3 display a significant CEST effect from a single slowly exchanging Eu³⁺-bound water molecule, making these PARACEST complexes potentially useful as vascular MRI agents. Yb2 also showed a detectable CEST effect from both the Yb³⁺-bound water protons and the …

Catalysis Of Nano Tio2 For Horseradish Peroxidase, Ya-Qi Zhu, Hai Wu, Hiu Liu, Jie Ma

Journal of Electrochemistry

Horseradish peroxidase immobilized on the surface of titanium dioxide nanoparticles and nanotube modified glassy carbon electrode.The HRP direct electron transfer reaction was compared between TiO₂ nanoparticles and nanotube GC electrode.The results demonstrated that the HRP on TiO₂ nanotube /GC electrode could catalyze electron exchange reaction between electroactivity center of HRP and electrode.And the research of antibody labeled HRP provides a selected signal for antibody-antigen immunoassay.

Electrochemical Behavior And Determination Of β,β-Dimethyl-Acry-Lalkannin, Li-Qing Lin, Jing-Hua Chen, Hong-Yan Wan, Xin-Hua Lin

Journal of Electrochemistry

The electrochemical behavior of the β,β-dimethyl-acry-lalkannin and a novel differential pulse voltammetric method for the determination of the β,β-DAL content were studied.Experiments indicated that the β,β-DAL has excellent adsorbability and the electrochemical reaction is a reversible two-electro and two-proton process.In phosphate buffer solution(pH 4.6),the differential pulse voltammograms for β,β-DAL reduction signals from +0.8~-0.4 V were monitored.The relationship between reduction peak current and concentration of β,β-DAL is linear in the range of 1.3×10^-7~ 1.7×10^-6 mol/L(r=0.9996).The detection limit is 4.0×10^-8 mol/L.This method is sensitive and reliable for the determination of the β,β-DAL in radix with satisfactory results.

Electrochemical Reduction Of Coals And The Oxygenic Functional Simulacrums Of Coals, Juan Lin, Zhao Wei

Journal of Electrochemistry

Electrochemical reduction of coals and the oxygenic functional simulacrums of coals has been studied.In this process,tetrabutylammonium was used as supporting electrolyte.The coal and the deoxidized coal were extracted by methanol.Qualitative analysis of the deoxidized products and the extractives was carried out on gas chromatograph-mass spectrometer.The deoxidized products of the oxygenic functional simulacrums of coals were analysed quantitatively with gas chromatograph spectrometer.The results show that the oxygenic functional groups on the coals surface decrease and the translation ratios of the oxygenic functional simulacrums of coals need further increase after electrochemical reduction,.The electrochemical tests show simultaneously the kinetics equations of every related …

Study On The Electricity Capability Of Ru((0.4-X))IrXTi(0.6)/Ti Electrode, Ling-Li Wang, Qiao Peng

Journal of Electrochemistry

The metal oxide anode of Ru_(0.4-x)Ir_xTi_0.6 has been prepared by thermal decomposition.The results indicate that,when the percent of IrO₂ is 10%,the electrode has low chlorine potential,high oxygen potential and excellent catalyze selectivity;strengthen life is long with IrO₂ content increased from 1.0h to 97h.It shows that the electrode anti-oxide corrosion perform is improved and intensifying life is long with addition of IrO₂.The film and reaction resistance are all fall with the addition of IrO₂.The addition of IrO₂ is in favor of thin crystal and makes the film more roughness.

Study On The Characteristics Of Vb(12) Modified Electrode By Electropolymerization, Hui-Ting Lian, Wen-Ji Wang

Journal of Electrochemistry

Preparation of the VB₁₂ modified electrode and its electrochemical characteristics were studied.The results showed that the VB₁₂ after electroactivated is able to electopolymerize on the GC by cyclic voltammetry(CV)in the DMSO solution.Differential pulse voltmmetry(DPV)showed that the VB₁₂ catalyzed the oxidation of NO₂^-,SO₃^2-and NH₂NH₂.The catalytic peak for NO₂^-on the modified electrode was observed at 0.76V(vs.SCE),but on the unmodified GC which at 1.0V.The catalytic currents increased linearly with the concentration of NO₂^-from 1.6×10^-6 to 4.3×10^-4 mol·L^-1 with a correlation coefficient …

Determination Of Ddopamine And Ascorbate On Gold Nanoparticle And 4,4-Bis (Methanethiol) Biphenyl (Mtp) Self-Assembled Monolayer Modified Gold Electrode, Hai-Yan Wang, Peng Liu, Ye Wang, Bao-Kang Jin

Journal of Electrochemistry

A new approach to construct an ampermetric biosensor was described.The 4,4-bis(methanethiol)biphenyl(MTP)is adsorbed on to a bare gold electrode to make self-assembled monolayers(MTP/Au SAMs).Then electrodeposited 2mg/mL HAuCl₄ at-200 mV,NG/MTP/Au electrode was prepared.When a differential pulse voltammetric(DPV)technique was used,the peak separation between DA and AA is 155 mV.Hence,the selective determination of dopamine(DA)and ascorbate(AA)in the binary mixture system can be performed.Under the chosen conditions,the peak currents are correspondent linearly to the concentrations of DA and AA in the range of 5.0×10^-7~1×10^-4 mol·L^-1 and 3.5×10^-6~1.0×10^-3mol·L^-1,respectively.The correlation coefficients were 0.998.The detection limit were 1.5×10 …

Corrosion Electrochemical Behavior Of Aluminum Flake Pigmented Water-Borne Epoxy Coating On Carbon Steel In Nacl Solution, Li-Li Xue, Li-Kun Xu, Qing-Fen Li, Hong-Qing Song, Wen-Juan Zhou, Guang-Zhang Chen

Journal of Electrochemistry

The corrosion electrochemical behavior of a water-borne epoxy coating pigmented with aluminum flake on carbon steel with artificial scratch defect was studied in 3.5% NaCl solution using electrochemical impedance spectroscopy(EIS)and scanning vibrating electrode technique(SVET).The results indicated that the defect presented anodic electroactivity at the initial stage of immersion,which extended gradually with time from the scratch into the neighboring coating,lowering the coating impedance.With further immersion,however,the electroactivity of the coating/steel interface decreased significantly due to the self-repairing of the corrosion products,causing an obvious increase of the coating impedance.In the later period of immersion,more scattered electroactive areas appeared under the coating because of …

Template Synthesis And Electrochemical Studies Of Ag(Core)Au(Shell) Nanowires, Li Ling, Ya-Xian Yuan, Min-Min Xu, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

Agcore Aushell nanowires with different thicknesses were prepared by combining template synthesis and chemical reduction method,and characterized by SEM and cyclic voltammetry(CV).The CV results revealed that the AgcoreAushell nanowires with pinhole were transferred to pinhole free structure after several potential scans.By using thiophenol(TP)and p-aminothiophenol(PATP)as probe,the surface enhanced Raman scattering(SERS)effect was investigated on the core-shell nanowires.The results indicated that AgcoreAushell nanowires could be served as a potential SERS substrate,and the difference in the spectral feature of PATP adsorbed onto Au and Ag nanowires enable us to diagnose the pinhole effect of core-shell nanowires by SERS.

Study On Fenbufen Electrochemical Behavior By The Linear Scanning Polarographic Method, Tian-Yang Xie, Hong-Gui Tuo, Ma-Tai Ding

Journal of Electrochemistry

The electrochemical behavior of fenbufen had been studied by linear scanning polarographic method.In 0.2mol L^-1 phosphate buffer solution(pH6.86),a sensitive reductive wave of fenbufen appeared at-1.38 V(vs.SCE).The linear relationship between the peak current and the fenbufen concentration in the range of 1.6～200.0 mg·L^-1(r=0.9958,n=10)were observed,the detection limit of this method was 0.8 mg·L^-1.RSD is 0.73%,found from the data of 6 independent determinations at the concentration level of 80.0 mg·L^-1.recovery ratio is 97.7%～109.2%.This fenbufen's electrochemical characteristic property may be used to determining the contents of tablets.

Electricity Generation From A Microbial Fuel Cell Employing Desulfovibrio Salexigens, Ping Ding, Hai-Bo Shao, Guang-Zhou Liu, Dong-Xia Duan, Ting Ma, Si-Jun Chen, Jian-Ming Wang, Jian-Qing Zhang

Journal of Electrochemistry

A microbial fuel cell of laboratory scale employing Desulfovibrio salexigens in lactate based seawater substrate was proposed.Electricity was continuously harvested after inoculation.During 20 days of fermentation/discharge,COD values of the substrate decreased by 61.7%,in which 9.81% was converted to electricity.

Simulation Of A Packed-Bed Electrochemical Reactor With Cooled Cathode For Continuously Producing Glyoxylic Acid By Oxalic Acid, Qing-Biao Li, Xiao-Hui Hu, Xue-Yun Chen, Wei Li, Yu-Zhong Su, Jun Li

Journal of Electrochemistry

Oxalic acid electrochemical reduction has been suggested as an important technology to produce glyoxylic acid;the packed-bed electrochemical reactor with cooled cathode(PERCC)has been proposed to solve the problem of lower space-time-yield that appeared in the parallel electrode reactor.Based on the mass balance equations,charge balance equations and kinetics equations of the system,a two-dimensional reactor model was established to describe the continuous operation process for producing glyoxylic acid from oxalic acid by PERCC.Using the orthogonal collocation method,the model equations could be numerically solved,and the glyoxylic concentration along the reactor length could be simulated.The modeling results indicated that the glyoxylic concentration increased quickly at …

The Research Of Several Electrodes For Spe Water Electrolysis, Jian-Bo Meng, Ge Sang, Yan Xue, Wei Cao, Xiao-Qiu Ye

Journal of Electrochemistry

Performances of the IrRu/Nafion 117/PbAg,IrRu/Nafion 117/Ni,IrRu/Nafion 117/TiNi,Ag/Nafion 117/Ni and C/Nafion 117/PtRu for the SPE water electrolysis have been investigated.The order of the electrocatalysis activity for the anodic electrodes as mentioned above is IrRu>Ag>C,and that of cathodic electrode is Ni>PbAg>TiNi.While the stability of TiNi was much better than Ni,and that of PbAg is best.Moreover,the current efficiency was raised with the increase of current density.

Study On The Contribution Of Cobalt Additives To Foam Nickel Electrodes, Xiao-Feng Li, Tong-Chi Xia, Shao-Peng Yi, Xiu-Juan Gu, Yu-Lin Song

Journal of Electrochemistry

Two incorporation ways of the cobalt additives into foam nickel electrodes,i.e.the co-precipitated and admixed method are used.The results of X-ray diffraction(XRD),cyclic voltammetry,electrochemical impedance spectrum(EIS)and galvanostatic charge-discharge curves show that(Ⅰ)there is a decrease in intensity and increase in half peak breadths of the diffraction peaks of Ni(OH)₂ with co-precipitated cobalt additive;(Ⅱ)the electrochemical activity of nickel hydroxide can be improved by both incorporation ways and the effect of admixed CoO is more notable;(Ⅲ)β-CoOOH derived from admixed CoO is not stable at lower potential,thus results in an irreversible capacity loss of nickel-metal-hydride(Ni-MH)battery after imposed overdischarged-state storage.