Chemistry Commons^™

Variable Frequency And Programmable Wave Power Supply Based On Dsp, Xiang-Dong Zhuo

Journal of Electrochemistry

This paper describes a ultra-low frequency,variable frequency and programmable wave power supply used for anodic corrosion of aluminum foils in electrolytic capacitors.Such a power supply is designed based on DSP and has stable output current and frequency.The output waveform is user programmable so that the corrosion process can be controlled according to the parameters set by users.

Electrochemical Performance Of Polytriphenylamine As A Novel Non-Aqueous Supercapcitor Cathode Material, Qiu-Jie She, Zhi-Kai Wei, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The PTPAn/active carbon compounds were synthesized by heterogeneous precipitation method.The SEM results show that the size of the PTPAn decreases from about 150 nm to few ten nanometers after being incorporated with active carbon.The PTPAn/active carbon compounds have excellent rate and cycling performance:the discharge capacity increases from 88.5 mAh/g to 105 mAh/g at 0.5 C charge/discharge rate and can reach to 70 mAh/g even at 40 C charge/discharge rate.And the capacity retention of the PTPAn/active carbon compounds remain almost unchanged after 1000 cycles at 40 C charge/discharge rate.

Novel Anion Exchange Membranes Base On Copolymer Of 2-(Diethylamino) Ethyl Methacrylate And Fluoro-Polyacrylate For Alkaline Direct Methanol Fuel Cells, Yan-Mei Zhang, Jun Fang, Ge Yan, Yong-Ze Zhuang

Journal of Electrochemistry

Anion exchange membrane fuel cells,which use anion exchange membranes as polyelectrolytes,have attracted more and more research interests recently.In this work,a series of hydroxyl-conducting anion-exchange membranes based on the copolymer of 2-(Diethylamino)ethyl methacrylate and fluoro-polyacrylate were prepared by radical polymerization,and their potential applications in alkaline fuel cells were assessed.It was shown that the ionic conductivity of the membranes reached 10^-2 S·cm^-1 at room temperature,while the methanol permeability was lower than 10^-7 cm²·s^-1.The maximum power density of fuel cell assembled with this membrane was achieved to be 43.2 mW·cm^-2 at room temperature,indicating possible application …

Interaction Of The Epirubicin Hydrochloride With Bovine Serum Albumin And Its Application, Hong-Fen Cheng, Yong Zhang, Jie-Qiong Song, Zeng-Qiao Wang

Journal of Electrochemistry

The linear sweep technique was used to study the electrochemical behavior of epirubicin hydrochloride.The results showed that there was a sensitive reduction peak at-0.34 V(vs.SCE) in pH 6.80 Tris-HCl buffer.When the BSA was added,the value of the reduction peak was reduced deeply.Accordingly,a new electrchemical determintation method of BSA was established.Under the optimum conditions,the decrease of the reduction peak currents of epirubicin hydrochloride were proportional to the concentrations of BSA in the range of 1.0×10^-9～1.0×10^-6 mol·L^-1(R=0.9973).The detection limit of the BSA was 8.05×10^-10 mol·L^-1.And the binding constant β of the epirubicin hydrochloride and …

Chemistry: Our Life, Our Future--Celebrate The International Year Of Chemistry, 2011, Zong-Rang Zhang

Journal of Electrochemistry

No abstract provided.

Applications Of Raman Spectroscopy Technique In Lithium Ion Batteries, Liang Zhao, Yong-Sheng Hu, Hong Li, Zhao-Xiang Wang, Hong-Xing Xu, Xue-Jie Huang, Li-Quan Chen

Journal of Electrochemistry

The Raman spectroscopy has been widely used in the study of lithium ion batteries.In this short review,we gave some examples of the applications of Raman spectroscopy in the study of electrode materials including carbonaceous materials,spinel LiM_xMn_2-x O₄,LiFePO₄,as well as polymer electrolytes,room temperaturemolten salt electrolytes and the solid-electrolyte interphase layers.The advantages and disadvantages of the ex-situ and in-situ Raman spectrum techniques are discussed.Using new Raman techniques to investigate Li-ion batteries are suggested.

Electrochemical Behaviors Of Nonionic Fluorosurfactant Zonyl Fsn Self-Assembled Monolayers On Au(111) And Au(100), Yong-An Tang, Jia-Wei Yan, Feng Zhu, Chun-Feng Sun, Bing-Wei Mao

Journal of Electrochemistry

The electrochemical behaviors of nonionic fluorosurfactant Zonyl FSN self-assembled monolayers on Au(111) and Au(100) were investigated by electrochemical scanning tunneling microscopy and cyclic voltammetry.In the potential range where the redox reaction of FSN molecules doesn′t occur,the structures of FSN self-assembled monolayers are uniform,which may suppress the adsorption of sulfate and the surface reconstruction of Au single crystal.At the initial stage of the oxidation of Au(111) and Au(100) surfaces covered by FSN self-assembled monolayers,Au(111) surface is characteristic of some protuberance,while Au(100) surface is characteristic of the movement of steps,however the structures of FSN self-assembled monolayers keep unchanged.Compared with Au(100),FSN self-assembled monolayers …

Electrochemical Double-Layer Capacitors Using Phenolic Resin-Based Carbon Fibers, Rong Xue, Jing-Wang Yan, Ying Tian, Bao-Lian Yi

Journal of Electrochemistry

Phenolic resin-based activated carbon fiber(ACF) was prepared by KOH activation.The electrochemical properties of pulverized phenolic resin-based carbon fiber(P-ACF) were examined in 6 mol·L^-1 KOH compared with that of the original ACF.P-ACF exhibited a better capacitive behavior and showed a larger specific capacitance(200 F·g^-1) as well as a lower capacitance decrease at high current densities.The pore resistance for ion migration(Rp) in P-ACF was lower(2.96 Ω) than that in ACF(4.65 Ω).Pulverization increased the exposure of the cross section,lowered the contact resistance between the carbon fibers and decreased the pore resistance for ion migration.

Low-Temperature Performance Of Li-Ion Battery With Fluoroethylene Carbonate Electrolyte, Chun-Wei Yang, Feng Wu, Bo-Rong Wu, Yong-Huan Ren, Jing-Wen Yao

Journal of Electrochemistry

The low temperature performance of electrolytes containing FEC including FEC+EMC, EC and PC, as well as the compatibility of electrolytes with LiFePO₄ anode and with MCMB cathode were investigated.The electrolyte exhibits a high value of ionic conductivity at low temperature.The stability of cathode was enhanced by the formation of SEI film at 1.6 V as a result of FEC reaction. The infrared spectra showed that FEC can suppress decomposition of other solvents during SEI formation, and lower the resistance of SEI on MCMB cathode. The electrochemistry test indicates that Li-ion batteries with FEC electrolyte display high capacity at low …

Electrooxidation Of Methanol On Multilayer Films Of Polypyrrole-Platinum Electrode, Ling Zhang, Long-Zhen Zheng

Journal of Electrochemistry

Multilayer films of polypyrrole-platinum electrode were fabricated by cyclic voltammetric technique.Electro-oxidation of methanol on this electrode was investigated with the aid of cyclic voltammetry and chronoamperometry.Results demonstrated that the multilayer of polypyrrole-platinum electrode behaved better electrocatalytic performance for electro-oxidaton of methanol and better poison resistant.Furthermore,with the increase of deposited platinum loadings,the rate controlling step on electro-oxidation reaction of methanol was changed from CO oxidation to sorption-desorption of hydrogen.

Electrochemical Capacitive Performance Of Polyaniline Electrode With Different Electrolytes, Yong-Tao Tan, Fen Ran, Ling-Ren Wang, Ji Liu, Ling-Bin Kong, Yong-Chun Luo, Long Kang

Journal of Electrochemistry

The polyaniline(PANi) for supercapacitor was prepared by chemical-oxidative polymerization.The SEM,FTIR data and electrochemical performance showed that,polyaniline nanoparticles were formed which were about 50 nm;the specific capacitances of PANi were 404 F/g,208 F/g and 279 F/g in 1 mol/L H₂SO₄,NaNO₃ and KOH,respectively,when the current density was 5 mA/cm².The concentrations of H₂SO₄ increased to 2 mol/L or 6 mol/L,the capacitances decreased to 330 F/g or 248 F/g.

Electrochemical Deposition Of Zinc Oxide Crystal Whiskers, Peng-Zeng Lu, Su Li, Jin-Qian Jia, Zhen-Hai Liang

Journal of Electrochemistry

Pine needle ZnO crystal whiskers were electrodeposited by anodization of zinc foil.The crystal whiskers were characterized by scanning electron microscopy(SEM) and X-ray diffraction(XRD) spectroscopy.The results show that the lengths and diameters of ZnO crystal whiskers are 200~300 nm and 20~50 nm,respectively,with the ratio of the length to diameter ranging from 10~15.The whiskers belong to wurtzite ZnO(JCPDS 36-1451) with good crystallinity and high purity.The crystalization behavior of ZnO was studied by cyclic voltammetry.The effects of the surface oxide layer at the zinc substrates and the [Zn(OH)₄]^2-concentration of the aqueous electrolyte on the formation of zinc oxide whiskers …

The Formal [4+3] Cycloaddition Between Donor-Acceptor Cyclobutanes And Nitrones., Andrew C Stevens, Cory Palmer, Brian L Pagenkopf

Chemistry Publications

The formal [4+3] cycloaddition of 2-alkoxy-1,1-dicarboxylate activated donor-acceptor cyclobutanes with nitrones is disclosed. The reaction forms structurally unique oxazepines in moderate to high yield with a wide scope of nitrones. In most cases either a diastereomeric mixture or a single diastereomer may be formed, depending on the reaction conditions.

Development Of Monolithic Stationary Phases For Cation-Exchange Capillary Liquid Chromatography Of Peptides And Proteins, Xin Chen

Theses and Dissertations

This dissertation focuses on the preparation of polymeric monolithic capillaries for ion exchange chromatography of peptides and proteins, since polymeric monoliths have shown promise for providing improved protein separations. Characteristics of monolithic columns include low back pressure, simplicity of fabrication and biocompatibility. Preparation of strong and weak cation-exchange monolithic stationary phases in 75 μm I.D. capillaries by direct in situ copolymerization was achieved using various functional monomers including sulfopropyl methacrylate, phosphoric acid 2-hydroxyethyl methacrylate, bis[2-(methacryloyloxy)ethyl] phosphate and 2-carboxyethyl acrylate with polyethylene glycol diacrylate and other PEG materials. The resulting monoliths provided excellent ion exchange capillary LC of peptides and proteins …

Gram Scale Synthesis Of The C(18)-C(34) Fragment Of Amphidinolide C., Nicholas A Morra, Brian L Pagenkopf

Chemistry Publications

The synthesis of the C(18)-C(34) fragment of amphidinolide C has been achieved via two routes, culminating in both the shortest (11 steps) and highest yielding (26% overall yield) approaches to this segment. The highly convergent approach will facilitate the synthesis of analogues, including the C(18)-C(29) fragment of amphidinolide F. Synthetic highlights include the selective methylation of a diyne, and the highly efficient use of a second generation cobalt catalyst in the Mukaiyama oxidative cyclization to form the trans-THF ring.

Fabrication Of Covalently Crosslinked And Amine-Reactive Microcapsules By Reactive Layer-By-Layer Assembly Of Azlactone-Containing Polymer Multilayers On Sacrificial Microparticle Templates, Eric M. Saurer, Ryan M. Flessner, Maren E. Buck, David M. Lynn

Chemistry: Faculty Publications

We report on the fabrication of covalently crosslinked and amine-reactive hollow microcapsules using 'reactive' layer-by-layer assembly to deposit thin polymer films on sacrificial microparticle templates. Our approach is based on the alternating deposition of layers of a synthetic polyamine and a polymer containing reactive azlactone functionality. Multilayered films composed of branched poly(ethylene imine) (BPEI) and poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) were fabricated layer-by-layer on the surfaces of calcium carbonate and glass microparticle templates. After fabrication, these films contained residual azlactone functionality that was accessible for reaction with amine-containing molecules. Dissolution of the calcium carbonate or glass cores using aqueous ethylenediaminetetraacetic acid (EDTA) or …

Polycationic Glycosides, Robert Engel, Ishrat Ghani, Diego Montenegro, Marie Thomas, Barbara Klaritch-Vrana, Alejandra Castaño, Laura Friedman, Jay Leb, Leah Rothman, Heidi Lee, Craig Capodiferro, Daniel Ambinder, Eve Cere, Christopher Awad, Faiza Sheikh, Jaimelee Rizzo, Lisa-Marie Nisbett, Erika Testani, Karin Melkonian

Publications and Research

Cationic lipids have long been known to serve as antibacterial and antifungal agents. Prior efforts with attachment of cationic lipids to carbohydrate-based surfaces have suggested the possibility that carbohydrate-attached cationic lipids might serve as antibacterial and antifungal pharmaceutical agents. Toward the understanding of this possibility, we have synthesized several series of cationic lipids attached to a variety of glycosides with the intent of generating antimicrobial agents that would meet the requirement for serving as a pharmaceutical agent, specifically that the agent be effective at a very low concentration as well as being biodegradable within the organism being treated. The initial …

Investigations Into Late Transition Metal Pincer Complexes As Possible Direct Partial Oxidation Catalysts, Raymond B. Lansing Jr.

Chemistry and Chemical Biology ETDs

This investigation examined aspects of a potential catalytic route for the partial oxidation of organic substrates using molecular oxygen as the oxidant. The proposed cycle begins with the insertion of molecular oxygen into a metal hydride bond to generate a metal hydroperoxide. The next step involves the transfer of an oxygen atom to an acceptor substrate to generate an oxidized species and a metal hydroxide. The starting metal hydride can then be regenerated in two viable ways, either through use of CO or H₂. The experimental plan involved the syntheses and characterization of new inorganic and organometallic complexes, …

Studies Of A Cyanine-Based Biosensor And Light-Induced Antibacterial Activities Of Oligo(Phenylene Ethynylene)S, Zhijun Zhou

Chemistry and Chemical Biology ETDs

This dissertation has been focusing on two subjects: biosensor development and light-activated antimicrobials. A cyanine-based fluorescent biosensor is developed with high sensitivity to detect the presence and activity of caspase-3/7. We demonstrated that supramolecular self-assembly can be useful for designing biosensors. A series of p-Phenylene Ethynylenes (OPEs) have been synthesized. Further photophysical studies show that these molecules have good singlet oxygen yields. The antimicrobial capability increases dramatically when exposed to UV-365 radiation, though dark biocidal activity can be obtained as well. This phenomenon is probably due to the high yields of singlet oxygen of these OPEs, which oxidizes unsaturated membrane …

Human Mitochondrial Hotdog-Fold Thioesterase: Hthem4 And Hthem5, Hong Zhao

Chemistry and Chemical Biology ETDs

Hotdog-fold acyl-CoA thioesterases (ACOTs) are found in all three kingdoms of life (Archaea, Bacteria and Eukarya). All the hotdog-fold thioesterases share common catalytic scaffold and function: hydrolysis of acyl-CoA or acyl-ACP (acyl carrier protein). However the biological roles that they perform vary greatly, different substrate specificity and catalytic efficiency assign unique set of biological functions to each of them, which is further defined by tissue distribution, cellular location, protein partners and regulators. The focuses of my doctoral studies, described in this dissertation, are two members of the human hotdog-fold thioesterase superfamily: human THEM4 and human THEM5. The genes encoding hTHEM4 …

Studies On Group 10 Pincer Carbene Metal Complexes, Agnes Mrutu

Chemistry and Chemical Biology ETDs

Selective oxidation chemistry is a topic of intense interest worldwide, in particular when using molecular oxygen (O₂) directly as the oxidizing species. The primary reason for using O₂ rather than other oxidants is to take advantage of the inexpensive nature of oxygen; however, the radical ground state of O₂ leads to non-selective reactions with organic substrates. As such, basic knowledge and understanding involving the fundamental reactions of O₂ with organometallic species will be required in order to overcome this lack of selectivity. The work presented in this dissertation has two main research goals to help …

Divergence Of Thioesterase Function: Human Bfit2, Escherichia Coli Enth, And Ydii, Danqi Chen

Chemistry and Chemical Biology ETDs

My doctoral research primarily focuses on two hotdog-fold thioesterases, EntH (also known as YbdB) from E. coli, and BFIT2 from Homo sapiens. The EntH (YbdB) gene is included in a large gene cluster that encodes the enzymes of the biosynthetic pathway leading to enterobactin. Building on the hypothesis that EntH might function in a house-keeping' role by liberating misacylated EntB, two potential pathways to EntB misacylation were identified, one involving the phosphopantetheinyl transferase EntD and the other involving 2,3-DHB-AMP ligase EntE. EntH displays thioesterase activity towards a variety of acyl and aryl-holo EntB adducts. Lastly, It was shown that EntF …

The Nature And Kinetic Analysis Of Carbon-Carbon Bond Fragmentation Reactions Of Cation Radicals Derived From Set-Oxidation Of Lignin Model Compounds, Adam S. Pimentel

Chemistry and Chemical Biology ETDs

The lignin peroxidase promoted α-carbon β-carbon bond cleavage of two diastereomeric pairs of dimeric lignin model compounds were investigated to determine which structural units are more readily cleaved. These model compounds, β-1 (1,2-diaryl-1,3-propanediol) and β-O-4 (1-diaryl-2-aryloxy-1,3-propanediol), represent the most common structural units present in the plant cell wall polymer lignin. The lignin peroxidase catalyzed reaction mechanism was shown to parallel two mechanistically well understood systems, the cerric (IV) ammonium nitrate promoted chemical reacton, and the dicyannoanthracene promoted photochemical reaction, both of which proceed by a SET mechanism. Product profiles and kinetic rate constants were determined and compared for all four …

Reversible Collapse Of The Langmuir Films Of A Series Of Triphenylsilyl Ether-Terminated Amphiphiles, Christine A. Devries, James J. Haycraft, Qiang Han, Farhana Noor-E-Ain, Joseph Raible, Patrick Dussault, Craig J. Eckhardt

Patrick Dussault Publications

The Langmuir films of a series of triphenylsilyl ether (TPSE)-terminated amphiphiles were investigated in order to explore the bulge amphiphile model developed by Haycraft et al. [Thin Solid Films, 515 (2007) 2990]. The TPSE series was examined using surface pressure– surface area isotherms over a range of temperatures (287–298 K) with simultaneous acquisition of Brewster angle microscopy images. The Langmuir films of the TPSE series exhibit the reversible collapse process characteristic of bulge amphiphiles, including an observation consistent with the reversed cybotactic cluster model and increased entropy upon collapse. No solid-like monolayer phases were found over the temperature …

Reciprocal Regulation Of Trek-1 Channels By Arachidonic Acid And Crh In Mouse Corticotropes, Andy K. Lee, James L. Smart, Marcelo Rubinstein, Malcolm J. Low, Amy Tse

Faculty Publications - Department of Biological & Molecular Science

Arachidonic acid (AA) is generated in the anterior pituitary gland upon stimulation by the ACTH secretagogue, CRH. Using the patch clamp technique,we examined the action of AA on the excitability of single pituitary corticotropes obtained from a transgenic mouse strain that expresses the enhanced green fluorescent protein driven by the proopiomelanocortin promoter. CRH evoked depolarization, but AA caused hyperpolarization. Under voltage clamp condition, AA caused a rapid inhibition of the delayed rectifier K current and then increased a background K current. Inhibition of AA metabolism did not prevent the activation of the K current by AA, suggesting a direct action …

Evaluation Of The Sensitivity Of Inventory And Monitoring National Parks To Nutrient Enrichment Effects From Atmospheric Nitrogen Deposition Northern Great Plains Network (Ngpn), T. J. Sullivan, T. C. Mcdonnell, G. T. Mcpherson, S. D. Mackey, D. Moore

United States National Park Service: Publications

Northern Great Plains Network (NGPN)

National maps of atmospheric N emissions and deposition are provided in Maps A and B as context for subsequent network data presentations. Map A shows county level emissions of total N for the year 2002. Map B shows total N deposition, again for the year 2002.

There are three parks in the Northern Great Plains Network that are larger than 100 square miles: Badlands (BADL), Missouri (MNRR), and Theodore Roosevelt (THRO). In addition, there are 10 other smaller parks.

Total annual N emissions, by county, are shown in Map C for lands in and surrounding …

Joule, John A. Heterocyclic Chemistry (Book Review), Jeffrey H. Glans

Chemistry & Physics Faculty Publications

Book review by Jeffrey H. Glans.

Joule, John A. and Keith Mills. "A Heterocyclic Chemistry. 5th ed. Wiley-Blackwell, 2010.

ISBN 9781405193658 (hardcover); 9781405133005 (pbk.)

Growth Factor Signaling Enhances Aromatase Activity Of Breast Cancer Cells Via Post-Transcriptional Mechanisms, Bin Su, Cynthie Wong, Yanyan Hong, Shiuan Chen

Chemistry Faculty Publications

It has been demonstrated that growth factors produced by breast cancer cells stimulate aromatase expression in both breast cancer and adjacent adipose fibroblasts and stromal cells. However, whether these growth factors affect aromatase activity by other mechanisms still remain unclear. In the current study, MCF-7aro and T47Daro aromatase transfected breast carcinoma cells were used to explore the mechanisms of post-transcriptional regulation of aromatase activity by growth factor pathways. Our study reveals that PI3K/Akt and MAPK inhibitors suppressed aromatase activity in MCF-7aro cells. However, PI3K/Akt pathway inhibitors stimulated aromatase activity in T47Daro cells. This is due to enhanced MAPK phosphorylation as …

Vector Space Language, Ronald Lovett

Topics in Quantum Mechanics

No abstract provided.

Observations Of Saharan Dust Microphysical And Optical Properties From The Eastern Atlantic During Namma Airborne Field Campaign, G. Chen, L. D. Ziemba, D. A. Chu, K. L. Thornhill, G. L. Schuster, E. L. Winstead, G. S. Diskin, R. A. Ferrare, S. P. Burton, S. Ismail, S. A. Kooi, A. H. Omar, D. L. Slusher, M. M. Kleb, J. S. Reid, C. H. Twohy, H. Zhang, B. E. Anderson

Chemistry

As part of the international project entitled "African Monsoon Multidisciplinary Analysis (AMMA)", NAMMA (NASA AMMA) aimed to gain a better understanding of the relationship between the African Easterly Waves (AEWs), the Sahara Air Layer (SAL), and tropical cyclogenesis. The NAMMA airborne field campaign was based out of the Cape Verde Islands during the peak of the hurricane season, i.e., August and September 2006. Multiple Sahara dust layers were sampled during 62 encounters in the eastern portion of the hurricane main development region, covering both the eastern North Atlantic Ocean and the western Saharan desert (i.e., 5-22° N and 10-35° W). …