Physical Chemistry Commons^™

Reactive Quenching Of Od A (2)Σ(+) By H-2: Translational Energy Distributions For H- And D-Atom Product Channels, J. H. Lehman, Jesse Lyle Bertrand , '11, Thomas Alex Stephenson, M. I. Lester

Chemistry & Biochemistry Faculty Works

The H- and D-atom products from collisional quenching of OD A (2)Sigma(+) by H-2 are characterized through Doppler spectroscopy using two-photon (2 S-2 <-<- 1 S-2) laser-induced fluorescence. Partial deuteration enables separation of the channel forming H + HOD products, which accounts for 75% of reactive quenching events, from the D + H2O product channel. The Doppler profiles, along with those reported previously for other isotopic variants, are transformed into product translational energy distributions using a robust fitting procedure based on discrete velocity basis functions. The product translational energy distribution for the H- atom channel is strongly peaked at low energy (below 0.5 eV) with a long tail extending to the energetic limit. By contrast, the D-atom channel exhibits a small peak at low translational energy with a distinctive secondary peak at higher translational energy (approximately 1.8 eV) before falling off to higher energy. In both cases, most of the available energy flows into internal excitation of the water products. Similar distributions are obtained upon reanalysis of D- and H- atom Doppler profiles, respectively, from reactive quenching of OH A (2)Sigma(+) by D-2. The sum of the translational energy distributions for H- and D- atom channels is remarkably similar to that obtained for OH A (2)Sigma(+) + H-2, where the two channels cannot be distinguished from one another. The product translational energy distributions from reactive quenching are compared with those obtained from a previous experiment performed at higher collision energy, quasiclassical trajectory calculations of the post-quenching dynamics, and a statistical model. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3644763]

Preparation And Characterization Of A Composite Of Gold Nanoparticles And Single-Walled Carbon Nanotubes And Its Potential For Heterogeneous Catalysis, Anne Shanahan, James Sullivan, Mary Mcnamara, Hugh Byrne

Articles

A single-walled carbon nanotube-supported gold nanoparticle composite was prepared and characterized by X-ray diffraction, scanning transmission electron microscopy/scanning electron microscopy/transmission electron microscopy, energy-dispersive X-ray analysis, atomic absorption spectroscopy, nitrogen adsorption, Raman spectroscopy, and ultraviolet-visible spectroscopy. The Au particles were found to be crystalline, with a well-defined and narrow particle-size distribution, centered around 7 nm. The activity and selectivity of the composite for solventless aerobic oxidation of a secondary alcohol were examined, and a conversion efficiency of 95% was obtained.

Excellent Adventures In Global Collaboration, Glenn W. "Max" Mcgee, Aracelys Rios

Publications & Research

No abstract provided.

I. The Synthesis And Coordination Chemistry Of Novel 6Π-Electron Ligands. Ii. Improvement Of Student Writing Skills In Chemistry Lab Reports Through The Use Of Calibrated Peer Review, Wilson Ngambeki William

Chemistry and Chemical Biology ETDs

ABSTRACT I

The goal of this study was to synthesize and characterize a set of coordination complexes containing 6π-cationic ligands. These compounds could be extremely useful as catalysts for the polymerization of olefins that are widely used in the synthetic polymer industry. The original strategy was to synthesize the 6π-cationic ligands using (Ph₂P)₃CH (1) and (Me₂P)₃CH (10) as precursors; however, both precursors 1 and 10 were found to be highly reactive leading to the fragmentation products (Ph₂P)₂CH₂ and (Me₂P)₂CH₂ respectively. In trying …

Structural Characterization Of Metal Binding In Metallo-Β-Lactamases Using X-Ray Absorption Spectroscopy, Robert M. Breece

Chemistry and Chemical Biology ETDs

In an effort to probe the structure and mechanism of metallo-β-lactamases, the metal-binding behaviors of several enzymes were studied using EXAFS (Extended X-ray Absorption Fine Structure). Three members of the metallo-β-lactamase subclass B1, BcII from Bacillus cereus, Bla2 from Bacillus anthracis and CcrA from Bacillus fragilis, were compared to examine metal-binding behavior within a subclass. Each system exhibits different metal-binding behavior including cooperative binding (BcII), sequential binding (CcrA), and differential binding between zinc(II) and cobalt(II) forms (Bla2). The metal-binding behavior of subclass B3 of L1 from Stenotrophomonas maltophilia was explored with RFQ (rapid-freeze quenched) EXAFS and site selective metal …

Study On Residual Powders Of Lithium-Ion Batteries With Different Voltages After Explosion, He Li, Zhi-Kui Chen, Ji-Na Cao, Guang-Chuan Liang

Journal of Electrochemistry

The residual powders of lithium-ion batteries at different voltages after explosion were obtained by using the battery impact testing machine. And these powders have been investigated by weighing, water solution and X-ray diffraction (XRD). The results showed that the integrity status of copper current collector and weight of residual powders decreased gradually with increasing of battery voltage, rising of burning temperature and releasing of burning duration time. The residual powders could be separated to insoluble powders and soluble powders by the water solution. The proportion of the insoluble powders is more (about 90%) including C, Co and CoO, while the …

Development Of Dehydrogenase-Based Bioanode Using Poly(Phenosafranin)-Functionalized Swcnt Nanocomposites And Its Application To Ethanol Biosensor, S. Saleh Farhana, Okajima Takeyoshi, Lanqun Mao, Takeo Ohsaka

Journal of Electrochemistry

A New type of dehydrogenase-based amperometric ethanol biosensor was constructed using alcohol dehydrogenase (ADH) which was immobilized on the edge-plane pyrolytic graphite (EPPG) electrode modified with poly(phenosafranin)-functionalized single-walled carbon nanotube (PPS-SWCNT). The PPS-SWCNT modified EPPG electrode was prepared by electropolymerization of phenosafranin on the EPPG electrode which was previously coated with SWCNT. The performance of the ADH/PPS-SWCNT/EPPG electrode was evaluated using cyclic voltammetry and amperometry in the presence of ethanol. The fabricated ethanol biosensor provided a reasonable sensitivity of 2.0 μA cm–2 mM–1 and a low detection limit (36 μM) for the electrocatalytic oxidation of ethanol with a linear concentration …

Surface Diffusion Of Adsorptive Species On Gold Nanoelectrodes, Bao-Fa Su, Wei Wang, Dong-Ping Zhan, Bin Ren, Zhong-Qun Tian

Journal of Electrochemistry

Gold nanoelectrodes were prepared successfully by a programmed laser puller. The Faraday adsorptions of oxygen and iodine, and the underpotential deposition of lead on the gold nanoelectrodes were investigated. The results showed that the active areas of nanoelectrodes were dramatically higher than their appearant geometry areas, which is caused by the surface diffusion of adsorptive species from the nanoscale gold/electrolyte interface to the adjacent gold surface.

Preparations And Characters For Acetamiprid Of Molecular Imprinted Polymer Electrochemical Sensors, Bin Liu, Yong-Xing Huang, Hui-Ting Lian, Hong-Mei Wu

Journal of Electrochemistry

A novel molecularly imprinted membranes electrochemical sensor with good memory capacity to acetamiprid was developed. Based on electrodeposition technique, chitosan was deposited onto the surface of gold electrode as a functional polymer matrix along with aimed molecules acetamiprid and glutaraldehyde as a crosslinking agent. Cationic probe Ru(NH₃)₆Cl₃ was employed to indirectly investigate the electrochemical characteristics as well as the imprinted effect of the sensors. The results showed that the sensors had a specific recognition to acetamiprid compared to the structural similarity midacloprid and other pesticide. There is more sensitive response to acetamiprid at imprinted sensors …

Electrochemistry In Neural Stimulation By Biomedical Implants, Zhou David, Greenberg Robert

Journal of Electrochemistry

Advances in biomedical engineering, micro-fabrication technology, and neuroscience have led to many novel and improved biomedical implants for electrical neural stimulation to restore human function and improve the quality of human life. Some examples of such biomedical devices are cochlear implants, visual implants, deep brain stimulators and spinal cord stimulators. One of the key components of biomedical implants is the stimulating electrodes. The electrodes, when in contact with living tissue, form an interface between the electronic device and the biological tissue. This paper reviews electrochemical aspects of neural stimulation implants. A brief introduction on the developments of biomedical implants is …

Electrochemical Performance Of Tin Dioxide/Carbon Xerogel Composites As Anode Materials For Lithium-Ion Batteries, Xiao-Jing Liu, Lin-Lin Qin, Yi-Ning Shi, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The tin dioxide/carbon xerogel composites were synthesized by using vacuum infiltration method. Structural characterization and morphology of the composites were investigated by using XRD, TEM and SEM techniques. BET test was performed to determine the pore size distributions of carbon xerogels and the composites. The results showed that the nano-sized SnO₂ particles (5~10 nm) were encapsulated in the pores of carbon xerogels. During the electrochemical tests the SnO₂ in the composites exhibited capacity retention of 61.9% after 100 cycles of charge-discharge tests at 100 mA/g.

Editor's Note, Editorial Office Of J.Electrochem.

Journal of Electrochemistry

No abstract provided.

Electrochemical Analysis Based On Molecular Recognition Of Nucleic Acids And Its Applications, Dian-Ming Zhou, Jian-Hui Jiang, Guo-Li Shen, Ru-Qin Yu

Journal of Electrochemistry

Nucleic acid as the carrier of genetic information and the functional molecules for molecular biology and bioanalytical chemistry has attracted increasing interest in electrochemical analysis. This review presents a brief outline of some electrochemical analytical assays based on molecular recognition of nucleic acids. Most of these methods are focused on the detection of nucleic acid sequence, genetic mutation and nucleic acids as functional molecules.

Study On The Fluorescent Carbon Nanodots With Electrochemical Methods, Bao-Ping Qi, Yan-Min Long, Lei Bao, Cui Liu, Zhi-Ling Zhang, Dai-Wen Pang

Journal of Electrochemistry

Carbon nanodots are a new class of fluorescent nanoparticles with a carbon-based core, which possess wavelength-tunable luminescence, high photostability, resistance to photobleaching, water-solubility, and ease of bioconjugation. Owing to their attractive merits, carbon nanodots like other carbon nanomaterials such as fullerene, carbon nanotubes and graphene, have attracted much attention. In addition, carbon nanodots can be inexpensively produced by electrochemical methods with simple post-processing under mild conditions. Electrochemical approaches have unique advantages in the analysis of surface structures and luminescence mechanism of materials. In this review, recent advances in electrochemical methods used for the synthesis and luminescence mechanism of fluorescent carbon …

Fabrication Of Ito Micro-Pore Electrochemical Sensor And The Detection Of Exocytosis, Hui Zhao, Ling Li, Pin-Gang He, Yu-Zhi Fang

Journal of Electrochemistry

Exocytosis is one of the major means for cells to transmit messages. Amperometric detection of exocytosis is an important method in studying communication between cells. In this study a new type of ITO micro-pore electrochemical sensor was fabricated by means of ITO and UV light lithographic mask and was used in the detection of exocytosis with promising results. Compared with the conventional method, the ITO micro-pore sensor can not only replace the carbon fiber electrode, but be combined with fluorescent or chemiluminescent methods in detecting the physiological phenomena of cells.

Study On The Electrochemical Behaviors Of Gc Electrode Modified With Carbon Nanotube-Polyelectrolytes And Its Application For Rutin Detection, Liang Hua, Xia-Qin Wu, Rong Wang

Journal of Electrochemistry

The electrochemical behaviors of rutin and ascorbic acid at single-wall carbon nanotube and polyelectrolytes (dimethyl-diallylammonium chloride, PDDA) film modified glassy carbon electrode was investigated. The cyclic voltammetric results showed that electron transfer of rutin at PDDA/SWCNTs/GC modified electrode is an adsorption-controlled process. The separation of oxidation peak potentials of rutin and ascorbic acid was more than 200 mV. The rutin concentration in the presence of AA were detected by differential pulse voltammetry (DPV). The experimental results indicated that the PDDA/SWCNTs/GC modified electrode can be used for the detection of rutin in the presence of high concentration of AA. The DPV …

Brief Introduction To Metal Corrosion And Protection, Hou-Yi Ma, Cong-Ying Cui, Ting Chen

Journal of Electrochemistry

This paper explains why corrosion processes are usually electrochemical in nature, describes the significance of electrochemical kinetic parameters of corrosion process, and briefly introduces the principles of corrosion protection, the most common corrosion protection methods and some special application of corrosion processes.

Effects Of Graphene On Electrochemical Behaviors Of Ni(Oh)2 As Supercapacitor Material, Zhen-Zhen Zhao, Wen-Bin Ni, Neng-Yue Gao, Hong-Bo Wang, Jian-Wei Zhao

Journal of Electrochemistry

The enhanced electrochemical properties of Ni(OH)₂ by the oxidation defected graphene were studied by both experimental method and theoretical calculation. The composite material of nano-Ni(OH)₂/graphene was prepared by potentiostatic deposition on the graphene substrate. Observed by TEM, the Ni(OH)₂ nanoparticles were well dispersed on the graphene substrate with the diameter of 5.0±0.5 nm. The capacitance of the system measured by the electrochemical test was 1928 F·g^-1. As indicated by the theoretical calculations, the composite material becomes conductive since Ni(OH)₂ is combined with surface functional groups of the graphene through the strong chemical interaction. …

Synthesis Of Limnpo4/C Used As Cathode Material For Lithium Ion Batteries, Xin Yang, Xue-Wu Liu, Gui-Chang Liu, Zhi-Cong Shi, Xin Li, Guo-Hua Chen

Journal of Electrochemistry

The LiMnPO₄/C composites were prepared using a solid-state reaction with addition of the resorcinol formaldehyde resin as the carbon source. The effects of reaction temperature and time on the crystal structure, morphology and electrochemical properties of the LiMnPO₄/C composites were investigated. The results show that the best performance was achieved with the LiMnPO₄/C composites synthesized at 600 ^oC for 12 h which had the particle sizes about 100~200 nm. The initial discharge capacities were 121.6 mAh·g^-1 at 0.02C, 110 mAh·g^-1 at 0.1C and more than 60 mAh·g^-1 at 1C. An …

Photogenerated Cathodic Protection Of Stainless Steel, Cheng-Gang Lin, Ze-Quan Lin, Jing Li, Chang-Jian Lin

Journal of Electrochemistry

A highly ordered Co-doped TiO₂ nanotube layers were fabricated by potentiostatic anodization of pure titanium in fluorinated electrolyte solutions followed by ion-exchange method. The structure and composition of the as-prepared Co-doped TiO₂ nanotube layers were characterized by SEM, XRD, UV-Vis, and XPS. The effects of dopant content on the morphologies, structural and photochemical properties of the TiO₂ nanotube arrays were investigated. The performances of photogenerated cathodic protection and the photoelectrochemical response for the Co-doped TiO₂ nanotube arrays under illumination and dark conditions were evaluated through the electrochemical measurements. The Co-doped TiO₂ nanotubes showed a stronger …

Synthesis And Electrochemical Behaviors Of Li2Coxmn1-XSio4 As A Cathode Material For Lithium-Ion Batteries, Lin Wang, Dong-Ping Lv, Yong Yang

Journal of Electrochemistry

We have successfully synthesized Li₂Co_xMn_1-xSiO₄/C (x=0, 0.1, 0.3, 0.5, 1)/C composites using hydrothermal assisted sol-gel process and ball-milling method. The results of X-ray diffraction show that the solid solutions of Li₂Co_xMn_1-xSiO₄ can be achieved when x≤0.3. The initial capacities increase from 70 mAh·g^-1 of Li₂MnSiO₄/C to 105 mAh·g^-1 of Li₂Co_0.3Mn_0.7SiO₄/C. Cyclic Voltammetry (CV) curves show that the replacement of Mn with Co can reduce the electrochemical polarization, making the insertion-extraction reaction …

Corrosion Characteristics Of Galvanized Flat Steel For Power Grounding In Nacl Solution Medium, Yong Li, Gao-Lin Wu, Bang-Fei Deng, Ping Yang, Xue-Ming Li, Qing-Bin Zong

Journal of Electrochemistry

The corrosion behavior of power grounding galvanized flat steel was studied by polarization measurement, electrochemical impedance spectroscopy and neutral salt spray test in 5% NaCl solutions. The surface morphologies of galvanized coating and structural properties of corrosion products were observed with scanning electron microscope and X-ray diffraction spectrometer, respectively. Results showed that under the temperatures of 20~60℃, the corrosion currents of galvanized flat steel increased with the temperature rising. The corrosion rate at 60℃ was 0.8408 mA·cm^-2, which is 2.9 times larger than that at 20℃. The corrosion rate dropped after reaching the maximal value of 1.95 mg·cm …

Electrelectrochemical Performances Of C-Coating And Co-Doping Lifepo4, Ying Bai, Jue-Ming Yang, Chun-Bo Qing, Wei-Feng Zhang

Journal of Electrochemistry

Phospho-olivine LiFePO₄ cathode materials were prepared by hydrothermal reaction at 200 ^oC. Sucrose was added as C-coating resource and Co was doped into the crystal lattice of LiFePO₄. In order to investigate the improvements in the electrochemical properties of Co-doped LiFePO₄, three samples, LiFePO₄, C-coated LiFePO₄ and C-coating-Co-doped LiFePO₄, were synthesized under the same preparation conditions. Charge/discharge studies reveal that the Co-doped LiFePO₄/C composite annealed at 400 ^oC exhibits marked improvement of specific capacity by diminishing the particle sizes and enhancement in the degree of crystallinity. …

Simultaneous Determination Of Dopamine(Da)And Epinephrine (Ep) At Ca/Gc Electrode, Wang Ren, Ying Zhang, Min-Jiao Li

Journal of Electrochemistry

The citric acid modified glassy carbon electrode (CA/GC) was prepared by potentiostatic technique and was used for detections of dopamine (DA), epinephrine (EP), and their mixtures by differential pulse voltammetry (DPV). The modified electrode shows the enhanced sensitivity and excellent electrochemical discrimination to DA and EP. The cathodic potential difference between DA and EP was about 380 mV, while no cathodic reduction of ascorbic acid (AA) was observed because the oxidation of AA is an irreversible reaction at the sensor. As a result, DA and EP could be determined simultaneously with the interferences of high concentrations of AA being eliminated. …

Applied Study Of Electrochemical Potentiokinetic Reactivation Method, Xiao-Qin Zha, Jian Liang, Xin-Yao Zhang, Ya-Jun Zhang, Li-Juan Zhang

Journal of Electrochemistry

The susceptibility to intergranular corrosion of overlay welding stainless steel composite plate (00Cr17Ni14Mo2) and low-Cr ferritic stainless steel (06Cr13R) was studied by electrochemical potentiokinetic reactivation (EPR) method. The results indicated that the ratio of the maximum current Ir/Ia generated by the reactivation EPR scan to that of the anodic scan is appropriate for evaluating the intergranular corrosion of 00Cr17Ni14Mo2, which is consistent with the H₂SO₄-CuSO₄-Cu method, and also appropriate for evaluating the intergranular corrosion of 06Cr13R, which is consistent with the oxalic acid test method. It shows that the EPR method can be applied …

Mechanistic Studies On Xanthine Oxidoreductase Enzymes, Abebe Berhane

Chemistry and Chemical Biology ETDs

In humans, the xanthine oxidoreductase enzymes are known to catalyze the final two steps of purine metabolism by converting hypoxanthine successively to xanthine and uric acid. Xanthine oxidoreductase also metabolizes a wide variety of drugs in vivo, and activates a number of antiviral prodrugs of clinical importance. Therefore, understanding the reaction mechanism of this enzyme is of prime importance in furthering our understanding of enzyme-drug interactions. In order to provide a greater understanding on the reaction mechanism, theoretical and enzymatic spectroscopic experimental approaches have been utilized. The theoretical approaches were used to elucidate the electronic structure and geometry of the …

Neutron Diffraction Of Nabd4: Phase Transition, Rietveld Structure Refinements, And Equation Of State, Guillermo Esparza, Esparza, Patricia Kalita, Andrew Cornelius

Undergraduate Research Opportunities Program (UROP)

NaBH4 is a hydride with possible applications as a hydrogen storage material for future renewable energy technologies. It’s dehydrogenation properties are enhanced with the mixture of particular catalysts through ball-milling techniques during which local pressures may exceed several GPa’s. It is for this reason that understanding the behavior of pressure induced phase changes of its crystalline unit cell is an area of interest.

Characterization Of Uranium Species In Sediments Under Iron And Sulfate Reducing Conditions Using Synchrotron-Based Techniques, Don Q. Pham, John Bargar

STAR Program Research Presentations

Uranium is one of the most common and problematic contaminants at legacy Department of Energy sites. Groundwater contamination is particularly problematic because it occurs at depth, is present in large volumes, and cannot be easily accessed for clean-up. One method of remediation being investigated is the bioreduction of soluble U(VI) to insoluble U(IV) complexes through the in-situ stimulation of metal-reducing bacteria. Understanding the structure of these uranium complexes can help us determine their fate and stability in groundwater and map out the biological process of uranium reduction by metal-reducing bacteria. In this study, we used the synchrotron-based techniques, X-ray absorption …

Exploring Methods For Earthquake Prediction: The Effects Of Water On The Flow Of Stress-Activated Electric Currents In Igneous Rocks, Aaron M. Jahoda, Friedemann T. Freund

STAR Program Research Presentations

Much of the devastation and damage of earthquakes can be attributed to the fact that they occur suddenly and without much warning, which limits the ability of people to evacuate and/or properly prepare. One method, however, that might be used to predict seismic events is the generation of electric currents in rocks when stresses are applied. It is observed in this research that the application of direct force onto samples of igneous rock causes the rocks to generate a measurable current, which is attributed to positive-hole charges moving within the oxygen sub-lattice. Because large and changing forces are acted upon …

A Theoretical Investigation Examining Dna Conformational Changes And Their Effects On Glycosylase Function, Allyn Brice

All Dissertations

Glycosylase enzymes initiate the process of base excision repair (BER) in order to prevent the irreversible modification of the genome. In the BER process a damaged DNA base is recognized, removed from the DNA sequence, and then the remaining abasic site is repaired. Glycosylase enzymes are responsible for the base recognition mechanism and catalysis of the base excision. One of the most studied glycosylase superfamilies is uracil DNA glycosylase (UDG). The UDG superfamily has demonstrated specificity for excising uracil, which is the deamination product of cytosine, from DNA sequences of prokaryotes and eukaryotes. Mismatch-specific uracil DNA glycosylase (MUG) is a …