Chemistry Commons^™

Fabrication Of Electrochemically Activated Glassy Carbon/Bismuth Film Electrodes For Sensitive Analysis Of Pb(2+) And Cd(2+), Kang Shi, Wen-Jing Wang, Kun Hu

Journal of Electrochemistry

The application of electrochemically activated glassy carbon (GC) in the in-situ preparing of bismuth film electrodes (BiFEs) to analyze Pb^{2 +} and Cd^{2 +} was investigated. The glassy carbon electrodes were electrochemically activated by either potentiostic or cyclic polarization in 1 mol·L^-1 NaOH solution. Experimental results show that employment of HCl solution as the analytical solution not only can reproducibly renew the electrochemically activated GC electrode surface with an electrochemical clear procedure, but also can greatly enhance the sensitivity of BiFes method for analysis of Pb^{2 +} and Cd^{2 +}. The test range thus …

Preparation And Application Of Ti/Ceo2-F-Pbo2 Electrode In Electrochemical Degradation Of Organics, Xun-Hua Wang, Tie-Ming Zhang, Shao-Ping Tong, Chun-An Ma

Journal of Electrochemistry

The CeO₂-modified PbO₂ on Ti plate (Ti/CeO₂-F-PbO₂) was prepared by electrodeposition. The SEM and XRD analyses indicated that the CeO₂ particle could be beuniformly co-deposited in the film of PbO₂. The results of electrochemical test showed that the Ti/CeO₂-F-PbO₂ anode had higher potential (1.83 V. vs. SCE) for oxygen evolution (OE) than the Ti/F-PbO₂ anode (1.78 V,vs. SCE). The degradation of 4-chlorophenol was carried out to test electrocatalytic performance of this novel electrode, which indicated that Ti/CeO₂-F-PbO₂ anode had high COD removal rate …

Synthesis Of Cosalen Composite In Apo-5 And Its Electrocatalytic Behaviour For Reaction Of Dioxygen Reduction, Rong Zhang, Li-Hua Tang, Bin-Bin Fan, Jing-Hong Ma, Rui-Feng Li

Journal of Electrochemistry

CoAPO-5 molecular sieve was hydrothermally synthesized. The Cobalt ions in CoAPO-5 were coordinated with the SALEN ligend diffusing into the channels of the molecular sieve to form CoSALEN complexes. The electrochemical behaviors and electrocatalysis for dioxygen reduction of the CoSALEN complex immobilized in APO-5 modified glassy carbon electrodes (GCEs) have been investigated by cyclic voltammetry (CV) and chronoamperometry (CA) in differrent pH aqueous solutions. The results showed that the PS/CoSALEN/APO-5 /GC modified electrode is of the high electrocatalytic activity towards dioxygen reduction in pH 6. 86 buffer solution with a reduced overpotential of 447 mV lower than bare GC electrode. …

Failure Reaction Mechanism Of Internal Short-Circuit For Lithium-Ion Batteries, He Li, Shen-Jun Yu, Zhi-Kui Chen, Guang-Chuan Liang

Journal of Electrochemistry

In this work, the battery impact testing machine has been used to study the failure progress of internal short-circuit (ISC) for lithium ion batteries. The reaction mechanisms between cathode/anode and electrolyte in the battery at different temperatures were characterized by differential scanning calorimetry (DSC), gas chromatography/mass spectrometry (GC/MS) and X-ray diffraction (XRD). The experimental results show that the ISC failure of the battery was mainly due to the reaction between cathode Li_0.5CoO₂ and electrolyte. The decomposition and oxygen evolution reactions of cathode occurred when the temperature reached a certain value. At the same time a fierce oxidation …

Hydrogen Evolution Reaction Activtity Of Ni-Ru-Ir Oxide Cathode Coating, Yin-Hui Fu, Xue-Ming Li, Wu-Lin Li, Jun Zhang

Journal of Electrochemistry

The Ni-Ru-Ir electrode coating was fabricated by thermal decomposition and oxidation. Electrochemical properties of Ni-Ru-Ir electrode coating and pure nickel cathode in the 30% NaOH solutions at 90 ℃(conditions of the industrial electrolysis) ,have been investigated by cyclic voltammetry,Tafel curves and chronoamperometry. The results show that the Ni-Ru-Ir oxide electrode coating exhibited high catalytic activity. At the current density of 0. 3 A·cm^-2,the lowest hydrogen evolution overpotential of Ni-Ru-Ir oxide electrode coating was about 300 mV lower than Ni. The roughness and excharge current density of Ni-Ru-Ir electrode coating were 32 and 4 times,respectively,larger than those of pure …

Study On Electrocatalytic Properties For Oxygen Evolution Of Ti/Iro2-Ta2O5 Anodes With Different Ir Contents, Yong-Lei Xin, Li-Kun Xu, Jun-Tao Wang

Journal of Electrochemistry

The anodes of Ti/IrO₂-Ta₂O₅ were prepared by Pechini method. The effects of coating loading on the surface morphology and electrochemical properties of the anodes were characterized by scanning electron microscope (SEM) ,energy dispersive X-ray detector (EDX), potentiodynamic polarization,cyclic voltammetry and accelerated life test. The results indicate that with the increase of the coating loading,the oxide anode presents evident IrO₂ crystallite segregation,and cracks become narrow and shallow. Moreover,it has larger electrochemically active surface area,better electrocatalytic activity for oxygen evolution and higher stability. It was observed that for an iridium content of 1.98 ～ 9. 08 …

Prerapation And Supercapacitor Property Of Mesoporous Carbon Nanofibers, Yong-Wen Wang, Ming-Bo Zheng, Jian Cao, Jie-Ming Cao, Guang-Bin Ji, Jie Tao

Journal of Electrochemistry

Two different mesoporous carbon nanofibers with large mesopore or core-shell structure were prepared by using the resol/F127 mixture to fill the AAO template. The morphology and structural parameters of the samples were characterized by SEM,TEM,and N₂ adsorption-desorption analysis. The supercapacitive behaviors of the electrodes were tested by cyclic voltammetry and galvanostatic charge-discharge. The results show that the specific capacitances of mesoporous carbon nanofibers increased obviously and the fine supercapacitive performances were achieved at high scan rate or large current density.

Synthesis And Electrochemical Properties Of Li3V2(Po4)3/C Cathode Materials For Lithium Ion Battery, Li-Ying Liu, Hai-Yan Zhang, Lian Chen, Yu-Chun Zhai

Journal of Electrochemistry

Cathode material Li₃V₂(PO₄) ₃ /C for Lithium-ion battery was synthesized by combination of ball milling and baking. Physical and electrochemical performances of as-prepared materials were characterized through XRD,EIS and galvanostatic cell cycling. The results show that the products were monoclinic Li₃ V₂ (PO₄) ₃ with well-developed crystal structure. At 0. 1C,0. 25C and 0. 5C,the initial discharge capacities were 150. 6,134. 1 and 107. 1 mAh·g^-1 ,respectively. Capacity retention rates were 87. 3% after 130 cycles at 0. 25C and 87. 2% after 105 cycles at 0. 5C. Charge-discharge …

Nano-Sized Au On Nickel Foam As Cathode Of Alkaline Al-H2O2 Semi Fuel Cell, Shu-Li Chen, Bang-An Lu, Yao Liu, Gui-Ling Wang, Dian-Xue Cao

Journal of Electrochemistry

Nano-sized Au particles were deposited on a nickel foam substrate by a fast spontaneous deposition method using AuCl₃ as the source of Au. The effects of AuCl₃ concentration and deposition time on the size and distribution of Au particles,and the performance of the obtained Au/Ni electrode as the cathode of Al-H₂O₂ semi fuel cell were investigated. It was found that after the nickel foam was immersed in a 2 mmol·L^-1 AuCl₃ solution for 60 s,Au particles with diameters smaller than 100 nm were deposited on its surfaces and cover the surface completely. The …

Blocking Method In Enzyme-Amplified Amperometric Dna Biosensor, Miao He, Wei Chen, Xiong-Wei Xu, Ai-Lin Liu, Xin-Hua Lin

Journal of Electrochemistry

Non-specific absorption of enzyme and nucleotide is a main source leading to the background staining in enzyme-amplified amperometric detection of DNA. To eliminate the background staining in this system, the blocking procedure by mercapto-hexanol (MCH) and bovine serum albumin (BSA) was studied systematically. The results show that the anti-fouling effect of BSA is better than that of MCH. A simple and efficient blocking strategy employing BSA as the sole blocking reagent was established and applied in the detection of PMLRARα fusion gene in acute promyelocytic leukemia. It can effectively eliminate the background staining,shorten the pre-processing time,and achieve strong signal amplification.

Electrochemical Behavior Of Kaempferide Interaction With Protein, Li-Qing Lin, Xin-Hua Lin, Jing-Hua Chen, Li-Ying Huang, Yin-Huan Liu, Guang-Wen Li

Journal of Electrochemistry

The electrochemical behavior of kaempferide at activated GCE and the interaction of kaempferide with human serum albumin(HSA) were investigated by cyclic voltammetry. A differential pulse voltammetric method has been proposed for the determination of the HSA with kaempferide. In pH 4. 5 phosphate buffer solutions (PBS) kaempferide can react with HSA to form an electrochemically non-active supermolecular complex at activated GCE,resulting in the decrease of oxidation peak (at 0. 468 V) without the change of peak potential. The decrease of the peak current is proportional to HSA concentration in the range of 0. 05 ～ 0. 25 mg/L. The limit …

Influence Of Ions Dimension On The Electric Field Activation Of Micro-Crystallite Carbon, Gang-Wei Sun, Wen-Hua Song, Guo Cheng, Wen-Ming Qiao, Li-Cheng Ling

Journal of Electrochemistry

Micro-crystallite carbon (CC) was synthesized by KOH activation of carbonized petroleum coke precursors. The porous properties structure and crystallite structure were characterized by N₂ adsorption-desorption, X-ray diffraction (XRD) measurements. The capacitive behavior of CC was investigated in the electrolyte of Et₄NBF₄/PC, Et₄NBF₄/AN, Bu₄NBF₄/PC and Bu₄NBF₄/AN, respectively. Results showed that the lower potential of electric field activation (EFA) was obtained in the solvent of AN than in PC, which was ascribed to the fact that smaller solvated ions dimension in AN facilitating the intercalation …

Electrochemical Behaviors Of Hydrazine In Bmimpf6 Solution At Ag Electrode, Jie Sun, Yan Li, Yi-Ling Feng, Rong Wang, Xia-Qin Wu

Journal of Electrochemistry

In this work, the electrochemical behaviors of hydrazine at Ag electrode in the room temperature ionic liquid, BmimPF₆, were studied by cyclic voltammetry. Results suggested that Ag electrode showed a good catalytic activity towards hydrazine oxidation. The catalytic peak current showed a good linear relationship with the hydrazine concentration in the range of 0 ～ 3.4 mmol/L. The rate-determining step of the electrocatalytic reaction involved one electron transfer form hydrazine molecule to Ag⁺ ion.

Density Functional Studies Of The Stability Of Clusters, Penee Clayborne

Theses and Dissertations

Theoretical studies using the Kohn-Sham density functional formalism have been carried out to identify and investigate the stability of a variety of atomic clusters for their use in cluster assembled materials. The stable behavior found in a cluster system provides a way to classify inorganic clusters. The clusters in this study can be categorized in one of the following, jellium, all-metal aromatic, Zintl analogue or as a covalent metal-carbide. By understanding the electronic structure and ultimately the stable nature of a cluster first, it is proposed one can construct assemblies based on the stable cluster. The methodology presented is a …

Functionalization Of Fibers Using Azlactone-Containing Polymers: Layer-By-Layer Fabrication Of Reactive Thin Films On The Surfaces Of Hair And Cellulose-Based Materials, Maren E. Buck, David M. Lynn

Chemistry: Faculty Publications

We report an approach to the functionalization of fibers and fiber-based materials that is based on the deposition of reactive azlactone-functionalized polymers and the "reactive" layer-by-layer assembly of azlactone-containing thin films. We demonstrate (i) that the azlactone-functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) can be used to modify the surfaces of a model protein-based fiber (horsehair) and cellulose-based materials (e.g., cotton and paper), and (ii) that fibers functionalized in this manner can be used to support the fabrication of covalently cross-linked and reactive polymer multilayers assembled using PVDMA and poly(ethyleneimine) (PEI). The growth, chemical reactivity, and uniformity of films deposited on these substrates …

Enhanced Oxygen Activation Over Supported Bimetallic Au-Ni Catalysts, Bert D. Chandler, Cormac G. Long, John D. Gilbertson, Christopher J. Pursell, G. Vijayaraghavan, K. J. Stevenson

Chemistry Faculty Research

New bimetallic Ni-Au supported nanoparticle catalysts were prepared by using dendrimer templated nanoparticles. Amine-terminated generation 5 polyamidoamine (PAMAM) dendrimers were anchored to a commercial silica with a siloxane linked anhydride. The dendrimer was then alkylated and used to template Ni-Au nanoparticles, which were subsequently extracted into organic solution as thiol monolayer protected clusters (MPCs). Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) indicated bimetallic nanoparticles of about 2 nm in size. Nanoparticles were deposited onto P-25 TiO2, and the capping thiol ligands were removed under flowing H2. DRIFTS infrared spectra of adsorbed CO showed only Au on the catalyst …

Catalytic Decomposition Of Peroxynitrite And Superoxide By Nafion Films Modified With Iron And Manganese Porphyrin, Amanda Stull, Victor Sarpong

Honors Theses

Nafion films alone and modified with inert electrolytes and metalloporphyrins were tested in their effectiveness of decomposition of aqueous peroxynitrite (PN) and superoxide. Films that were modified with a cationic manganese porphyrin, which has been shown to be responsible for catalytic decomposition of superoxide ion, were found to be most effective. Peroxynitrite was generated in solution by the decomposition of 3-morpholinosydnonimime (SIN-1) that generates nitric oxide and superoxide ion, which rapidly combine to form peroxynitrite. The tyrosine analogue 4-hydroxyphenylacetic (4-HPA) was used to trap the PN in pH 7.00 PBS buffer and was its nitrated product was detected by observing …

Uv Irradiation On Bacteriophage Survival, Sherri Tomlinson

Honors Theses

Bacteriophage is of great interest because of its potential role in controlling bacterial populations in our environment. UV exposure has a damaging effect on the virus decreasing lytic ability. This study set out to test the effects of UV radiation, in amounts comparable to local environmental conditions, on bacteriophage T2. The virus was placed in a Petri dish in a PBS medium and exposed to UV radiation at 365nm. The irradiated virus was allowed to infect E. coli and plated. The plaques formed were counted to determine lytic activity of the virus with respect to UV irradiation. The results showed …

Effect Of Anions On The Iron Release Pathways Of Human Serum Transferrin, Rashmi Subhash Chander Sharma

Dissertations

Transferrin, the serum iron transport protein in humans, is used to transport 30-40 mg of iron per day through blood. The accessibility of transferrin makes it an attractive target for iron cheating therapeutic agents used in the treatment of iron overload. There is an ongoing search for ligands which can accelerate the rate of iron release, as the currently approved drug DFO has a very slow rate for iron removal. Previous studies have shown that anions can accelerate the rate of iron release. Studies on the effect of anions on the rates of iron release from C-terminal monoferric transferrin at …

Ultrafast Optical Study Of Small Gold Monolayer Protected Clusters: A Closer Look At Emission, S. Hei Yau, O. Varnavski, John D. Gilbertson, Bert D. Chandler, G. Ramakrishna, T. Goodson

Chemistry Faculty Research

Monolayer-protected metal nanoclusters (MPCs) were investigated to probe their fundamental excitation and emission properties. In particular, gold MPCs were probed by steady-state and time-resolved spectroscopic measurements; the results were used to examine the mechanism of emission in relation to the excited states in these systems. In steady-state measurements, the photoluminescence of gold clusters in the range of 25 to 140 atoms was considerably stronger relative to larger particle analogues. The increase in emission efficiency (for Au₂₅, Au₅₅, and Au₁₄₀ on the order of 10^-5) over bulk gold may arise from a different mechanism …

Microwave Spectroscopy And Structures Of Several Substituted Acetylenes And Fluorocarbons, Joseph A. Fournier

Honors Scholar Theses

The structures of two substituted acetylene compounds have been characterized from their microwave rotational spectra. In the first study, two structures of 6-methyl-3-heptyne have been determined. This compound can be thought of as an ethyl group separated from an isobutyl group by a C≡C spacer. Both structures have the ethyl and isobutyl groups eclipsed, consistent with the dominant interaction determining the orientation about the acetylene axis being the weak dispersion attraction between the end groups. One structure is with the isobutyl group in a symmetric conformation and the other with the isobutyl group asymmetric. In addition, the microwave spectrum of …

Assessing Commercial Organic And Conventionally Grown Vegetables By Monitoring Selected Heavy Metals Found In Them., Charles Kafui Dotse

Electronic Theses and Dissertations

Commercially available organic and conventionally grown vegetables were studied by quantitative determination of selected metals in them and to determine if any differences found are statistically significant. These findings can help the consumers to determine if the vegetable products are within the recommended maximum limits as proposed by the joint FAO/WHO Expert committee on organic foods designation. Eight edible vegetables were purchased from local stores in both the organic and conventionally grown categories. Samples were digested with concentrated nitric acid and the metals monitored were zinc, copper, lead, iron, cadmium, and nickel using flame atomic absorption. The concentration range for …

Regioselective Formation Of Α-Vinylpyrroles From The Ruthenium-Catalyzed Coupling Reaction Of Pyrroles And Terminal Alkynes Involving C–H Bond Activation, Ruili Gao, Chae S. Yi

Chemistry Faculty Research and Publications

The cationic ruthenium catalyst Ru₃(CO)₁₂/NH₄PF₆ was found to be highly effective for the intermolecular coupling reaction of pyrroles and terminal alkynes to give gem-selective α-vinylpyrroles. The carbon isotope effect on the α-pyrrole carbon and the Hammett correlation from a series of para-substituted N-arylpyrroles (ρ = −0.90) indicate a rate-limiting C−C bond formation step of the coupling reaction.

A Preliminary Study In Probing Rapid Method Of Isotope 87sr/86sr Analysis By Electrospray Ionization -Quadrupole Ion Trap - Mass Spectrometry, Sheng Song

Student Theses and Dissertations

The isotope ratio 87Sr/86Sr, typically reported in geologic investigations, is obtained by direct electrospray ionization of aqueous sample containing Sr(II), Rb(I) and 18c6. At relatively high concentrations, we observed favorable formation of Sr2+(18c6)₂ and Rb+(18c6) over Sr2+(18c6) complexes. Physical separation of Sr2+(18c6)₂ and Rb+(18c6) as well as separation of Sr2+(18c6)₂ is observed by simply injecting the sample solution to ESI source using simple PEEK tubing in neutral pH. These phenomena are caused by the difference in mobility of the complexes and masked by the gas phase association reactions. ESI-QITMS successfully obtained the expected isotope distribution of Sr(II) …

Use Of A Robust Dehydrogenase From An Archael Hyperthermophile In Asymmetric Catalysis–Dynamic Reductive Kinetic Resolution Entry Into (S)-Profens, Jacob A. Friest, Yukari Maezato, Sylvain Broussy, Paul H. Blum, David B. Berkowitz

David Berkowitz Publications

Hyperthermophilic archaea are of great interest in evolutionary microbiology, owing to their ability to withstand high temperatures, and often extremes of pressure, pH and salinity. Enzymes from these organisms¹ may offer particular opportunities for asymmetric synthesis, complementary to approaches with mesophilic enzymes,² or those involving enzyme³ and pathway⁴ reengineering. However, perhaps due to a bias that hyperthermophilic enzymes have “narrow substrate specificities,”⁵ archaeal extremophiles remain a largely untapped resource in asymmetric synthesis.⁶

Herein, we disclose a remarkably general Dynamic Reductive Kinetic Resolution (DYRKR) entry into (S)-profens, including several important NSAIDs. The enzyme employed is …

Terminal Deoxynucleotidyl Transferase: The Story Of A Misguided Dna Polymerase, Edward A. Motea, Anthony J. Berdis

Chemistry Faculty Publications

Nearly every DNA polymerase characterized to date exclusively catalyzes the incorporation of mononucleotides into a growing primer using a DNA or RNA template as a guide to direct each incorporation event. There is, however, one unique DNA polymerase designated terminal deoxynucleotidyl transferase that performs DNA synthesis using only single-stranded DNA as the nucleic acid substrate. In this chapter, we review the biological role of this enigmatic DNA polymerase and the biochemical mechanism for its ability to perform DNA synthesis in the absence of a templating strand. We compare and contrast the molecular events for template-independent DNA synthesis catalyzed by terminal …

On Probing Human Fingertips In Vivo Using Near-Infrared Light: Model Calculations, Jerry Goodisman, Joseph Chaiken

Chemistry - All Scholarship

We probe volar-side fingertip capillary beds with nearinfrared laser light and collect Raman, Rayleigh, and Mie scattered light and fluorescence. The results are interpreted using radiation transfer theory in the single-scattering approximation. The surface topography of the skin is modeled using the Fresnel equations. The skin is treated as a three-layer material, with a mean-field treatment of tissue composition and related optical properties. The model, with a reasonable choice of tissue parameters, gives a remarkably accurate account of the features of actual measurements. It predicts the optimal values for the incident angle of the laser beam and the distance between …

A Novel Pervious Cement Reaction Barrier (Pcrb) In Situ Arsenic Remediation System, Morgan Liane Jones

Masters Theses & Specialist Projects

No abstract provided.

Degradation Of Chlorophenols In Swine Waste, Srilatha Gangula

Masters Theses & Specialist Projects

Naturally occurring plant derived phenols can be degraded through bacteria in swine waste. Chlorinated phenols, which are not naturally present in the environment, are toxic and generated from industrial activities as such petrochemical, pharmaceutical, plastic, rubber, pesticide, iron, steel, paper production, coal conversion, wood preserving, and cellulose bleaching. Large scale coal gasification and carbonization plants are another source of chlorinated phenols. Although not normally present in the environment, chlorinated phenols are structurally similar to many plant derived phenolics.

It is our hypothesis that bacteria located in swine wastes may also have the ability to degrade chlorinated phenols. Identifying situations (and …

Tuning Quantum Dots Optical Properties By Temperature And Concentration Modulation, Amber Sexton

Renée Crown University Honors Thesis Projects - All

Quantum dots have recently been awarded attention due to their tunable optical and spectroscopic properties. The optical and spectroscopic behavior of quantum dots was investigated as a function of mean particle size. Manipulation of the reaction conditions and constituents impact the controllability of size and surface conditions. Therefore, synthesis of CdSe and CdS semiconductor nanoparticles with tunable particle size were created using temperature, time, and composition as variables. Analytical techniques used to characterize the nanoparticles included fluorescence and electronic absorption. The effect of temperature, aside from changing the size of the particle, also eliminated defects on the surface and caused …