Physical Sciences and Mathematics Commons^™

Incorporating Electron-Transfer Functionality Into Synthetic Metalloproteins From The Bottom-Up, Jing Hong, Olesya A. Kharenko, Michael Y. Ogawa

Chemistry Faculty Publications

The alpha-helical coiled-coil motif serves as a robust scaffold for incorporating electron-transfer (ET) functionality into synthetic metalloproteins. These structures consist of a supercoiling of two or more R helices that are formed by the self-assembly of individual polypeptide chains whose sequences contain a repeating pattern of hydrophobic and hydrophilic residues. Early work from our group attached abiotic Ru-based redox sites to the most surface-exposed positions of two stranded coiled-coils and used electron-pulse radiolysis to study both intra- and intermolecular ET reactions in these systems. Later work used smaller metallopeptides to investigate the effects of conformational gating within electrostatic peptide-protein complexes. …

Generating New Specific Rna Interaction Interfaces Using C-Loops, Kirill A. Afonin, Neocles B. Leontis

Chemistry Faculty Publications

New RNA interaction interfaces are reported for designing RNA modules for directional supramolecular self-assembly. The new interfaces are generated from existing ones by inserting C-loops between the interaction motifs that mediate supramolecular assembly. C-Loops are new modular motifs recently identified in crystal structures that increase the helical twist of RNA helices in which they are inserted and thus reduce the distance between pairs of loop or loop-receptor motifs from 11 to 9 base-stacking layers while maintaining correct orientation for binding to cognate interaction interfaces. Binding specificities of C-loop-containing molecules for cognate molecules that also have inserted C-loops were found to …

Observation Of Fano Asymmetry In Raman Spectra Of Srtio3 And Cax Sr1-Xtio3 Perovskite Nanocubes, Sarbajit Banerjee, Dae In Kim, Richard D. Robinson, Irving P. Herman, Yuanbing Mao, Stanislaus S. Wong

Chemistry Faculty Publications and Presentations

Bulk SrTi O3 is cubic and not expected to exhibit any first-order Raman scattering. However, nanocubes of SrTi O3 with an edge length of 80±10 nm show strong first-order Raman scattering originating from the breaking of symmetry caused by frozen surface dipoles (local tetragonality) and the presence of nanoscopic polar domains (arising from incorporated impurities). Rapid polarization fluctuations within these nanoscopic ferroelectric regions interfere with a polar phonon, resulting in a Fano-like asymmetric line shape in these SrTi O3 nanocubes, as well as in Ca0.3 Sr0.7 Ti O3 nanocubes.

Calix[4]Arene-Based Synthetic Nanotubes, Voltaire Guanlao Organo

Chemistry & Biochemistry Dissertations

Nanoscale science and technology represents a tremendous opportunity to gain unprecedented insight into the unique phenomena that exists at the nanometer scale, and to use that knowledge to develop materials and devices with novel characteristics. This dissertation explores the unique properties of calix[4]arene-based synthetic nanotubes, the process of filling and characteristics of materials confined in one dimension. Chapter 1 provides an overview of recently developed nanoscale materials, particularly single-walled carbon nanotubes and their ability to encapsulate materials in a one-dimensional configuration. Molecules inside carbon nanotubes are reported to exhibit structural and dynamic properties that are not observed in the bulk. …

Novel Functions And Physiological Significance Of Ral Interacting Protein - Rlip76 In In Vitro And In Vivo Models, Ewa L. Zajac

Chemistry & Biochemistry Dissertations

This dissertation is divided into four parts. The first part is an introduction of energy dependent xenobiotic transporters and their relevance in multidrug resistance. However, the main focuse is the description of RLIP76 protein, non-ABC transporter, which it the most efficient transporter of glutathione conjugates and anti-cancer drugs. The second part describes materials and methods that were used in two investigated projects. The third part explains the correlation of RLIP76 with signaling protein POB1 and an involvement of these two proteins in apoptosis of lung cancer cells. The effect of recombinant POB1 and its deletion mutant POB11-512, on transport activity …

Synthesis And Characterization Of Inosamines, Sing Raj Gurung

Masters Theses

This project is concerned with the preparation of scyllo-inosarnine hydrochloride 6, a biologically active compound, which bears six successive stereogenic centers. The synthesis of this compound would help elucidate the involvement of inosamines in biological nitrogen fixation. myo-Inositol served as the starting material to synthesize target compound 6. Regioselective protection and deprotection of myo-inositol provided azide 43 as key intermediate. In the final steps deprotection of five benzyl groups and reduction of azido group was achieved by catalytic hydrogenation. scyllo-Inosamine hydrochloride 6 was fully characterized by m.p., ¹H NMR, ¹³C NMR, IR, EA and via …

Development Of Methods For The Study Of Phosphoproteins, Zhaoyuan Chen

Theses and Dissertations

Characterization of phosphoproteins-including detection, identification of phosphoproteins and identification of phosphorylation sites-is mostly done with radiolabeling and proteomic techniques. Three main topics related to phosphoprotein characterization are included in this dissertation. First, large-scale characterization of the CHO (Chinese hamster ovary) cell phosphoproteome was done using two dimensional gel electrophoresis (2DE) separation, visualization of phosphoproteins by radiolabeling or a phosphoprotein specific dye, followed by MALDI-TOF identification. Because radiolabeling of phosphoproteins is very sensitive and straightforward to quantify, such analysis can give a clear picture of the relative phosphosphorylation of proteins present in a sample. But there are also limitations to this …

Development Of Novel Synthetic Methods Utilizing Organometallic Reagents And Total Synthesis Of Eupomatilone 2, Chunlan Chen

Masters Theses

This dissertation summarizes the development of novel synthetic methods involving organometallic reagents and their application in the total synthesis of the natural product eupomatilone 2. These newly discovered reactions include the palladium-catalyzed cross-coupling of allyl acetates with organosiloxanes and the diastereoselective synthesis of cis- and trans-a-methylene-y-lactones utilizing Baylis-Hillman adducts as precursors. Another important aspect of the research is the application of some of the methods in total synthesis of eupomatilone 2.

The new synthetic methodologies involving organometallic reagents developed in this dissertation are important transformations in modern organic synthesis. Mild reaction conditions, tolerance of various organic functional groups, and high …

Applications Of Mass Spectrometry To Synthetic Copolymers, Elizabeth Angela Stewart

Masters Theses

Over the last decade, application of mass spectrometry has grown immensely especially in polymer characterization. The focus of this thesis is to assess and extend the applicability of matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) and electrospray ionization mass spectrometry (ESI MS) in the analysis of synthetic copolymers.

Characterization of a non-ionic copolymer was attempted. The copolymer was styrene-co-maleic anhydride, which is in a class of copolymers that are used for commercial applications where low viscosity, high polarity and/or high reactivity are needed. MALDI-TOF MS was employed to obtain weight and number average molecular weight values (M_w and …

Surface Modification Of Pigments And Its Role In Offset Ink Setting, Wei Gu

Electronic Theses and Dissertations

Ink setting affects offset print quality issues such as print mottle and print gloss. It is known that ink setting depends on many factors, such as the nature of the substrate, the properties of the coating, and the ink formulation. However, the role of pigment surface chemistry in offset ink setting is unknown. From an experimental perspective, it is difficult to determine the role of the surface chemistry as it requires paper coatings that are similar in physical properties and differ only in the pigment surface chemistry. The aim of this study was two-fold. The first was to apply methods …

Electrostatic Assembly Of A Redox Catalysis System For Detection Of Glutamate, Alice Harper, Mark Anderson

Mark R. Anderson

Interfacial assemblies capable of determining glutamate by redox catalysis are prepared by electrostatic assembly of alternating layers of ferrocene poly(allylamine) polymer and glutamate oxidase on a gold electrode. Deposition of the polymer was confirmed in cyclic voltammetry measurements by the presence of a surface wave corresponding to the oxidation of the ferrocene group. In the presence of glutamate in the adjacent electrolyte solution, the current increases and approaches a pseudosteady state, consistent with redox catalysis. Electrodes modified with glutamate oxidase had a linear response to glutamate up to 0.0045 M with sensitivity of 20 μA/cm2 and a limit of detection …

Reaction Mechanism Of V(Ⅳ)/V(Ⅴ) Redox Couple At Graphite Felt Composite Electrode Bonded With Conductive Carbon Plastic, Xiao-Gang Li, Ke-Long Huang, Liusu-Qin Liusu-Qin, Ning Tan, Li-Quan Chen

Journal of Electrochemistry

The rate-determining step of V(Ⅳ) /V(Ⅴ) redoxreaction was investigated at graphite felt(GF)composite electrode by various techniques: cyclic voltammetry,polarization curve and impedance spectroscopy.Cyclic voltammetry analysis indicated that V(Ⅳ) /V(Ⅴ) redox reaction at GF electrode is quasi reversible.Acertain chemical reaction step is suspected to follow the electron transfer step of this reaction.The Tafel slopevalue(0.124) obtained from the polarization curve agrees well with theoretical value(0.12),which supposingthe electron transfer step was the rate-determining step.Impedance Spectroscopies at various potentials werestudied and simulated by equivalentcircuits.The impedance value of the electron transfer step modified is greatlyhigher than the others,which shows that the electron transfer step is the …

Synthesis Of Monolithic Carbon/Nickel Oxide Composite Electrode Material And Cyclic Voltammetry Characteristics, Tian-Ying Guo, Jing-Wei Zhu, Mou-Dao Song, Bang-Hua Zhang

Journal of Electrochemistry

Monolithic carbon/nickel oxide composite materials were synthesized by carbonization of phenol formaldehyde gels that were ion-exchanged with Ni~(2+).Atomic absorption spectroscopy and powder X-ray diffraction technique were used to characterize the chemical composition and physical structure of the materials.The nickel dope amount for this method can reach 5.9 %(by mass).Subsequent cyclic voltammetry experiments indicate that the materials exhibit best capacitive performance at the nickel content of 4.4 %.

Electrochemical Behavior Of Buprofezin On Glass-Carbon Electrode, Qi Wang, Chang-Guo Chen

Journal of Electrochemistry

Electrochemical behavior of Bup has been investigated by means of cyclic voltammetry,linear sweep voltammetry,differential pulse voltammetry and square wave voltammetry.The results indicate that the electrochemical behavior of Bup on the surface of glassy carbon electrode is corresponding to a irreversible two-protons and two-electrons process with absrption.The square wave voltammetry for determination of Bup in actual samples has been established.

Facilitated Effect Of Ag To Oxygen Transportation In Pem Fuel Cell Air Cathodes, Hong-Feng Xu, Jian-Hua Dong, Xiang-Li Hou

Journal of Electrochemistry

Silver(Ag) was deposited in the pores of Nafion membrane by ion exchange and succedent hydrogen reduction;the structures of Nafion-Ag membrane were measured by TEM and XRD,the diffusion coefficients of oxygen in Nafion-Ag was determined by electrochemical limited current method.The results showed that after deposited silver,the pores in the Nafion were enlarged by silver grains;the oxygen diffusion coefficient was increased about four times.By introducing silver in the thin Nafion film around the cathode catalyst,the performance of PEM fuel cell have a evident increasing in high current density, which shows the facilitated effects of silver to oxygen transportation in PEM fuel cell.

Column Thin-Layer Electrolytic Self-Regenerating Suppressor For Ion Chromatography, Wei-Xiong Huang, Rong-Zong Hu, Shu-Chao Wu, Dan-Mei Pan

Journal of Electrochemistry

A new type of column thin-layer electrolytic selfregenerating suppressor for ion chromatography was proposed.A porous electrode was used in this suppressor,incorporating the electrode and the electrolyte compartment,and eliminating the voltage across the electrolyte compartment.The design of the column thin-layer configuration of suppression compartment simplified the structure of suppressor and reduced the dead volume,improving the performance of suppressor.

Structure And Electrochemical Characteristics Of Lifepo_4 Prepared By The Polyacrylates-Pyrolysis-Reduction Method For Li-Ion Batteries, Li-Hong Yu, Yu-Liang Cao, Xiao-Fei Zhang, Han-Xi Yang, Xin-Ping Ai

Journal of Electrochemistry

The cathode material of olivine LiFePO_(4) was prepared by a novel method of polyacrylate-pyrolysis-reduction.XRD demonstrates that the material have the olivine structure.SEM photo shows an average particle-size of about 100 nm with a well distribution.Electrochemical test of cycling at a constant current reveals the discharge capacity of 138 mAh/g and a good cycling stability.It is a novel practicable technology to prepare LiFePO_(4) by using polyacrylate-pyrolysis-reduction method.

Stm Tip-Induced Nanostructuring-Replacement Method To Construct Pt Surface Nanostructures, Jin-Gang Wang, Jing Tang, Zhao-Bin Chen, Bing-Wei Mao

Journal of Electrochemistry

STM tip-induced surface nanostructuring based on "Jump-to-contact" mechanism is a nanostructuring technique that has the highest resolution in aqueous solutions.However,for metals that have high cohesive energy,atoms would transfer from surface to tip instead,which limits the wide application of this technique.In this paper,we present a two-step Nanostructuring-Replacement method to construct metal nanoclusters that cannot be obtained directly via the "Jump-to-contact" mechanism.The method is demonstrated to construct Pt nanoclusters that are of great interest in catalysis and electrocatalysis but cannot be constructed via the "Jump-to-contact" mechanism.Since Cu is the most intensively studied and successful system in the tip-induced nanostructuring,it is utilized as …

Preparation And Electrochemical Property Of Bam Boo-Shaped Silicon Nanotubes, Zeng-Tao Liu, Yan-Peng Fu, Chen Li, Yong Yang

Journal of Electrochemistry

A novel 1D bamboo-shaped silicon nanotubes was synthesized by chemical vapor deposition with Au catalyst and their electrochemical properties were primarily studied.The results showed that these silicon nanotubes were amorphous with the length about tens micrometer and the diameter about one hundred nanometer.Cyclic voltammetry studies showed that Li ions could intercalate into such silicon nanotubes at two location,i.e.,from the conjoint location and the wall of the hole.Meanwhile,the bamboo-shaped structure could help release the expansion of volume,which is usually serious in the lithium batteries.

Preparation And Electrochemical Characterization Of Anatase Tio_2 Nanotubes, Bin Cao, Jin-Wei Xu, Ling-Hong Ding, Wei-Feng Zhang

Journal of Electrochemistry

Titanium oxide nanotubes were prepared by hydrothermal treatment of anatase-type TiO_(2) powders and NaOH solution in an autoclave.Transmission Electron Microscopy and X-ray Diffraction showed that the product is anatase-type TiO_(2) nanotubes.The constant charge-discharge current and cyclic voltammetry exhibited the TiO_(2) nanotubes have a large initial lithium insertion capacity of 260 mA·h/g and good reversibility.This study indicates that TiO_(2) nanotubes might be a good negative electrode materical for second lithium battery in the future.

Fabrication Of Gold Electrode Array Based On Co_2 Laser Ablation, Wei Zhang, Jiang-Qun Xiao, Yong-Liang Zhou

Journal of Electrochemistry

A rapid process is described to produce single or multiple electrodes of any shape based on CO_(2) laser ablation for microfluidic chip.The method is as follow: coating a kind of material as sacrifice layer on a piece of glass with sputtered Cr and Au;designing the needed pattern on a computer;selecting proper parameters and ablating with CO_(2) laser;wiping of Au/Cr and sacrifice layer,and obtain electrodes at last.The microfluidic chip was gotten by reversely bonding with a piece of PDMS,and sealing around with PDMS prepolymer.The mask' effect is the main factor that influencing electrode quality.The width of electrodes could be 100 μm.Demonstrated …

Electrochemical Behavior Of Tanshinoneⅱa And Its Determination, Guang-Wen Li, Xin-Hua Lin, Xiao-Yan Lin

Journal of Electrochemistry

The electrochemical behavior of TanshinoneⅡA was investigated by voltammetry at a glassy carbon electrode.And Differential Pulse Voltammetric method for determination of TanshinoneⅡA was developed.In pH 4.0 acetate buffer solution,the relationship between oxidation peak current of Differential Pulse Voltammetric and the concentration of Tanshinone ⅡA was linear in the range of 3.0×10 ~(-7)～2.0×10 ~(–5) mol·L~(-1).The detection limit had been estimated as 2.0×10~(-8) mol·L~(-1).The interference of other components in the preparation could be efficiently eliminated by the glassy carbon electrode.This method can be used for the determination of TanshinoneⅡA in real sample with satisfactory results

Synergistic Functions Of Trimethl Phosphate And Vinylene Carbonate As Additives For The Li-Ion Batteries, Zhi-Yuan Tang, Yan-Bing He, Quan-Sheng Song, Yu-Hong Chen, Yuan-Gang Liu, Qiang Liu

Journal of Electrochemistry

The cooperative effects of trimethl phosphate and vinylene carbonate as additives for Li-ion batteries are investigated by using the cyclic voltammetry,electrochemical impedance spectroscopy and scanning electronic micro-photographs.The results show that the combination application of TMP and VC as additives for Li-ion batteries not only enhances safety of the batteries,but also improves their cycling performance.The reason may be ascribed to firstly VC being reduced and the reduction product polymerized to form excellent solid electrolyte interface(SEI) layer on the surface of graphite electrode during the first charge and discharge process,which prevents effectively the decomposition of TMP on the surface of the graphite …

Phase-Transfer Technique For Polymer-Protected Noble Metal Nanoparticles, Xing-Li Feng

Journal of Electrochemistry

A novel phase-transfer method was developed based on the decrease of PVP's solubility in water with increasing temperature,by means of which PVP-protected gold,silver and platinum nanoparticles can be conveniently transferred from aqueous phase to 1-butanol phase.Monodispersed metal nanoparticles were electrochemically synthesized at first in the aqueous,and then 1-butanol of appropriate volume was added to the aqueous phase.Heating the oil-water mixture to 80 ℃ under vigorous stirring would make metal nanoparticles leave the aqueous phase and enter into the 1-butanol phase,with high phasetransfer efficiency and without aggregation between nanoparticles.An electrochemical method to synthesize metal nanoparticles in the oil-water mixtures was further …

Study Of The Electrooxidation Of Glycerol On Oxide And Pd/C Composite Catalysts, Zhi-Yuan Yan, Chang-Wei Xu, Pei-Kang Shen

Journal of Electrochemistry

Oxide and Pd on carbon composite catalysts have been prepared by intermittent microwave heating(IMH) method.The performance of the catalysts for glycerol oxidation in alkaline solution is studied by electrochemical techniques.It is shown that the Pd/C catalyst is active for glycerol electrooxidation.However,the oxide-Pd/C catalysts are even better in terms of the onset potential that is more negative and peak current density.The ratio of oxide to Pd is optimized according to the electrochemical measurement.The results reveal that the addition of oxide into the Pd/C induces the synergistic effect for glycerol electrooxidation.

Electrochemical Properties Of The Modified Carbon Nanotubes, Chun-An Ma

Journal of Electrochemistry

Powder micro-electrodes were prepared from raw carbon nanotubes and carbon nanotubes modified by carboxyl.The electro-reduction properties of both the raw and open-ended carbon nanotubes in p-Nitrophenol solution were investigated.The FTIR spectrum result indicated that the functional groups are successfully fixed on the surface of the carbon nanotubes after nitric acid treatment.The cyclic voltammetry results show that the electrochemical activity of carboxyl-modified carbon nanotubes was improved.The mechanism of electro-(reduction) for the carbon nanotubes after acid treatment was discussed.

Studies And Applications Of Phosphoric Acid Treatment On Low Voltage Formed Aluminum Foils, Lan Sun

Journal of Electrochemistry

The surface of low voltage formed foil for Al electrolysis capacitors is treated with phosphoric acid solution.The effects of concentration of phosphoric acid solution,temperature and process time on specific capacitance and the time of hydration resistance with standing voltage are studied.The optimum condition is presented.The properties of low voltage formed foil have been improved by applying this method on the product line.

Fabrication And Characterization Of Gadolinium Hexacyanoferrate Modified Electrode, Yan-Mao Shi, Pan Du, Ping Wu, Yao-Ming Zhou, Chen-Xin Cai

Journal of Electrochemistry

A new electroactive polynuclear inorganic compound of rare earth metal hexacyanoferrate,gadolinium hexacyanoferrate(GdCHF),was prepared by electrochemically deposition on the surface of a glassy carbon electrode with a potential cycling procedure.The result of SEM indicated that the GdHCF was in the form of particles adhered on the surface of electrode.There were two different shapes and sizes of GdHCF forming on the surface of electrode.FTIR spectrum of GdHCF showed a very strong and sharp peak,which located at 2062.5 cm~(-1) and corresponded to the stretching vibration of the C≡N group in the GdHCF.The cyclic voltammetric results indicated that the GdHCF/GC electrode exhibited two pairs …

The Synthesis,Structure And Electrochemical Performances Of Lithium Iron Phosphate, Hui Xie

Journal of Electrochemistry

The lithium iron phosphate cathode materials were synthesized by solid-state reaction combined high-rate ball milling under the temperature ranging from 400 ℃ to 700 ℃.The crystalline structure,morphology of particles,and electrochemical performance of the sample were investigated by X-ray diffraction,scanning electron microscopy and charge-discharge test.The results showed that the sintering temperature had great influences on the crystal structure,morphology and electrochemical performances of LiFePO_(4).The sample synthesized under 600℃ showed the best charge-discharge performances with the first specific discharge capacity of(128.8) mAh/g and the 15~(th) specific discharge capacity of 129.1 mAh/g at 0.1C rate,each charge-discharge cycling efficiency being 99.7%.Also the sample showed good …

Novel Electrochemical Method For Synthesis Of Nanostructured Materials Of Noble Metals Based On Poly(N-Vinylpyrrolidone) (Pvp), Wei Pan

Journal of Electrochemistry

Gold nanocrystals with controllable size were synthesized through a simple electroreduction method using poly(N-vinylpyrrolidone)(PVP) of different polymerization degree as both stabilizer and shape-controller for gold nanoclusters.Individual gold nanoparticles spontaneously assembled into the wire-and ring-shaped nanoparticle aggregates depending on the PVP's dynamic stretching and curling,and precursor nanoparticles grew into flat,single-crystalline nanoprisms with thickness of dozens of nanometers based on the oriented aggregation between particles.Besides,core-shell Au/Ag nanoparticles were conveniently synthesized through two-step electroreduction of noble metal ions in the presence of PVPK30.The electrochemical synthetic method based on PVP provides a new path for preparation of noble metal nanostructured materials with different shape …