Chemistry Commons^™

Influence Of Electrode Hydrophobicity On Performance Of Alkaline Polymer Electrolyte Fuel Cells, Li-Sheng Tan, Jing Pan, Yao Li, Lin Zhuang, Jun-Tao Lu

Journal of Electrochemistry

In the present work, we study the influence of the electrode hydrophobicity on the performance of alkaline polymer electrolyte fuel cells (APEFCs). QAPS or xQAPS is employed as the membrane and the ionomer, while PTFE is used as a hydrophobic additive in order to adjust the electrode hydrophobicity. We find that enhancing the hydrophobicity of anode can promote the performance of APEFCs, while a moderate hydrophobicity of cathode is required to achieve optimal performance. By using xQAPS as the electrolyte and adding some PTFE in the anode, a peak power density of 132 mW·cm^-2 can be obtained at a …

Progress Of Lithium Rich Cathode Materials For Li-Ion Batteries, Jie Zhang, Jiu-Lin Wang, Jun Yang

Journal of Electrochemistry

Lithium rich materials xLi₂MnO₃·(1-x)LiMO₂ (0-1 and low cost. However, the large irreversible capacity during the first cycle, low rate capability and structure collapse during cycling remain impediments in developing these cathodes for applications. The structure analyses and charge/discharge mechanisms for lithium rich materials are currently main research contents. Although whether the lithium rich materials are solid solutions or composite is still controversial, oxygen release mechanism on the first charge 4.5 V plateau of lithium rich materials has come to consistency. Several modifications, such as bulk doping, surface coating and microstructure control, demonstrate promising strategies to …

Electrochemical Performance Of Al-Doped Spinel Limn2O4 Cathode Material For Li-Ion Batteries, Yong-Long Wang, Wen-Ge Wang, Qian Zhang, Xin Wang, Jian-Sheng Cao, Shi-Hai Ye

Journal of Electrochemistry

Spinel LiMn₂O₄, a cathode material for Li-ion batteries, is featured as good high-rate performance, low cost and environmental friendly. The pristine and Al-doped LiMn₂O₄ samples were prepared by sol-gel method. The structure and micromorphology of the as-prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results demonstrated that the as-prepared LiMn₂O₄ samples had a typical cubic spinel structure and were composed of sphere-like particles with a diameter range of 300 ~ 500 nm. Galvanostatic charge-discharge tests showed that the LiMn₂O₄ samples doped …

Electrocatalytic Mechanism And Porous Electrode Mass Transfer Process In Membrane Electrode Assembly For Direct Methanol Fuel Cells, Xin-Dong Wang, Yi-Tuo Wang, Gui-Cheng Liu, Meng Wang, Zhe Tian

Journal of Electrochemistry

Direct methanol fuel cell (DMFC) is considered to be a promising commercial energy conversion device for portable electronics due to its many advantages. In order to improve the performance of DMFC, many companies and research institutes have been launching the deep research and obtaining a lot of conspicuous achievements. In this paper, the electrocatalytic mechanism and porous electrode mass transfer process in membrane electrode assembly (MEA) are analyzed. In addition, combined with the preparation process of MEA, multilayer ordered structures and internal transfer process of the cell, recent progresses of MEA in DMFC are discussed.

Electrochemical Nanofabrication Using Polyacrylamide Hydrogel As Soft Stamps, Wen Sun, Hai-Tao Fan, Da-Xiao Zhang, Dong-Jie Hu, Yong-Liang Zhou

Journal of Electrochemistry

The fabrication resolution of electrochemical wet stamping (E-WETS) was enhanced to several hundred nanometers from several ten micrometers by using polycarylamide gel (PAG) as soft stamps and through optimized processes. The PAG stamp was cured on a nanopatterned soft mold and soaked with 0.2 mol·L^-1 KCl solution, then contacted with a silicon wafer with gold film and applied with electric field. And the gold nanopatterns were achieved by the selective anodic dissolving, the diameter of fabricated gold spot was around 200 nm. The parameters which affected the fabrication processes have been discussed in detail.

Fabrication And Performance Of Lani0.6Fe0.4O3-δCathode Modified By Coating With Gd0.2Ce0.8O2 For Intermediate Temperature Solid Oxide Fuel Cell, Rui-Xuan Ren, Bo Huang, Xin-Jian Zhu, Yi-Xing Hu, Xiao-Yi Ding, Zong-Yao Liu, Ye-Bin Liu

Journal of Electrochemistry

The symmetric cell of LaNi_0.6Fe_0.4O_3-δ/Sc_0.1Zr_0.9O_1.95/LaNi_0.6Fe_0.4O _3-δ was fabricated with screen printing method. A LaNi_0.6Fe_0.4O_3-δ (LNF) cathode was modified by coating with nano-sized gadolinium-doped ceria (GDC, Gd_0.2Ce_0.8O₂) prepared using a simple combustion process within the pores of the cathode. According to the electrochemical impedance spectra (EIS), the polarization resistance of the pure LNF was 0.70 W·cm² at 750 ºC, while 0.13 W·cm² for the 21.3% GDC (by mass)-coated LNF cathode at the …

Optimization Of Electroless Silver Plating Process On Fabric Surface Without Activation And Sensitization, Bo Lian Wang, Ya Ping Zhao, Zai Sheng Cai

Journal of Electrochemistry

Silver was deposited homogeneously on the surface of polyamide fabric by electroless plating without activation and sensitization. The electroless silver plating process was optimized with the orthogonal array testing strategy. It is found that the optimum conditions are the electroless plating time of 50 min with the concentrations of silver nitrate, sodium hydroxide and ammonium hydroxide being 14 g·L^-1, 6 g·L-1 and 130 mL·L^-1, respectively. The surface morphologies, compositions, and phases of fabric samples were characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM-EDS), X-ray diffraction (XRD). The wear-resisting property was tested by friction fastness …

Investigation Of Water-Molecule Complexes And Their Catalytic Effect On Important Atmospheric Reactions, Taylor Scott Cline

Theses and Dissertations

This dissertation is a collection of works that investigates issues related to environmental chemistry. The first portion of this research explores the role of water vapor on the kinetics of important atmospheric reactions. Work is presented on the self-reaction of β-hydroxyethyl peroxy radical (β-HEP) and the catalytic increase in reaction rate by water vapor. β-HEP serves as a model system for investigating the possible role of water vapor in perturbing the kinetics and product branching ratio of atmospheric reactions of other alkyl peroxy radicals. The self-reaction rate coefficient of β-HEP was investigated between 276-296 K with 1.0 × 10^15 to …

Identification Of Beryllium-Dependent Peptides Recognized By Cd4+ T Cells In Chronic Beryllium Disease, Michael T. Falta, Clemencia Pinilla, Douglas G. Mack, Alex N. Tinega, Francis Crawford, Marc Giulianotti, Radleigh Santos, Gina M. Clayton, Yuxiao Wang, Xuewu Zhang, Lisa A. Maier, Philippa Marrack, John W. Kappler, Andrew P. Fontenot

Mathematics Faculty Articles

Chronic beryllium disease (CBD) is a granulomatous disorder characterized by an influx of beryllium (Be)-specific CD4+ T cells into the lung. The vast majority of these T cells recognize Be in an HLA-DP–restricted manner, and peptide is required for T cell recognition. However, the peptides that stimulate Be-specific T cells are unknown. Using positional scanning libraries and fibroblasts expressing HLA-DP2, the most prevalent HLA-DP molecule linked to disease, we identified mimotopes and endogenous self-peptides that bind to MHCII and Be, forming a complex recognized by pathogenic CD4+ T cells in CBD. These peptides possess aspartic and glutamic acid residues at …

Extending Single Molecule Fluorescence Observation Time By Amplitude-Modulated Excitation, Lydia Kisley

Faculty Scholarship

We present a hardware-based method that can improve single molecule fluorophore observation time by up to 1500% and super-localization by 47% for the experimental conditions used. The excitation was modulated using an acousto-optic modulator (AOM) synchronized to the data acquisition and inherent data conversion time of the detector. The observation time and precision in super-localization of four commonly used fluorophores were compared under modulated and traditional continuous excitation, including direct total internal reflectance excitation of Alexa 555 and Cy3, non-radiative Förster resonance energy transfer (FRET) excited Cy5, and direct epi-fluorescence wide field excitation of Rhodamine 6G. The proposed amplitude-modulated excitation …

Optical Properties Of Silver And Gold Tetrahedral Nanopyramid Arrays Prepared By Nanosphere Lithography, M. Tabatabaei, A. Sangar, N. Kazemi-Zanjani, P. Torchio, A. Merlen, Francois Lagugne-Labarthet

Chemistry Publications

Tetrahedral nanopyramids made of silver and gold over ITO/glass surfaces are fabricated. Our protocol is based on nanosphere lithography (NSL) with the deposition of thicker metal layers. After removing the microspheres used in the NSL process, an array of metallic tetrahedral nanostructures of ~350-400 nm height is formed. The reported procedure avoids the use of any stabilizing surfactant molecules that are generally necessary to segregate the individual particles onto surfaces. We focus here on the optical and the physical properties of these plasmonic surfaces using near-field spectroscopy in conjunction with finite difference time domain (FDTD) modeling of the electric field. …

Polypeptides, Systems, And Methods Useful For Detecting Glucose, Sylvia Daunert, Kendrick Turner, Smita Joel, Laura Rowe

Chemistry Faculty Patents

The presently-disclosed subject matter provides biosensors for detecting molecules of interest. The biosensors include a polypeptide capable of selectively-binding glucose, wherein the polypeptide molecule is selected from: an unnatural analogue of wild type glucose binding protein; a fragment of wild type glucose binding protein; and an unnatural analogue fragment of wild type glucose binding protein.

Englerin-A, Curtis Allred, Dr. Merritt Andrus

Journal of Undergraduate Research

My project has been to synthesize smaller, simpler analogs of a molecule that is effective against renal cancer, called englerin-A.

Modeling Of An Ion Exchange Reaction Involving Decamethylcucurbit[5]Uril In The Gas Phase, Jacob Hedelius, Dr. David Dearden

Journal of Undergraduate Research

Mathematical modeling is both common and increasingly expected in scientific research, to both predict and to explain results. Models are used in many disciplines, from describing cellular process in biology, weather patterns in planetary science, to galaxies in physics. As part of my studies with the Office of Research and Creative Activities (ORCA), I created a simple model for reactions of the molecule decamethylcucurbit[5]uril (mc5) in the gas phase.

How Tmrna/Smpb Rescue Complex Binds To Stalled Ribosomes, Matthew Mcdowell, Dr. Allen Buskirk

Journal of Undergraduate Research

Ribosomes are large complexes made up of ribosomal RNA and proteins and are the site of protein synthesis. However, ribosomes occasionally run into problems during this process and will stall during translation. Fortunately, two molecules known as tmRNA and SmpB are made by cells in order to free stalled ribosomes. We sytematically mutated G517, C518, C519 and A520 in the ribosome to see if binding fidelity decreases, and to see if these bases affect the activity of tmRNA/SmpB in ribosomes during ribosome rescue. This assay however, gave us no informative results because we were only looking at endpoints of its …

The Tat Two Hybrid System, Joshua Browning, Dr. Allen Buskirk

Journal of Undergraduate Research

The TAT two hybrid system for discovering novel stalling peptides met with some immediate challenges that ultimately resulted in the abandonment of this project. The feasibility for using this method to discover new peptide sequences that would cause the stalling of translation within an elongating ribosome became unlikely.

Transmission Electron Microscope Imaging Of Lipid-Body Cox Localization, Andrew Broadbent, Dr. Daniel Simmons

Journal of Undergraduate Research

The laboratory of Dr. Daniel L. Simmons, my mentor, studies the cyclooxygenase (COX) enzyme. Dr. Simmons is one of the world’s foremost authorities on COX, he having discovered one of its two known types, COX-2. The COX enzyme, which exists in many organisms, including humans, is responsible for producing molecules that trigger inflammation. For this reason, understanding COX is important: for example, aspirin works by deactivating the enzyme, and COX could play a role in the inflammation linked to diseases like type-II diabetes and cancer. Thus, greater knowledge of its workings could aid those suffering from a variety of diseases.

Laser-Induced Fluorescence Of No2, Joseph Mosley, Dr. Jaron Hansen

Journal of Undergraduate Research

The effects of water vapor on the kinetics and product branching ratio of the reaction of organic peroxy radicals (RO₂) with nitrous oxide are under investigation. Hyrdrocarbon combustion produces organic peroxy radicals which then react with NO to form NO₂ or organic nitrates (RONO₂). This reaction which branches is shown below:

Identification Of Novel Ribosome Stalling Peptides Using The Tat-Two Hybrid, Benjamin Van Leeuwen, Dr. Allen Buskirk

Journal of Undergraduate Research

Dr. Buskirk discontinued my previous project on discovering novel ribosomal stalling sequences shortly after the start of the semester because of its lack of relevance to more current ribosomal research trends. While there are still an unknown number of stalling sequences that have yet to be discovered, the current research has moved away from that field into more novel ribosomal research. Therefore, I was not able to finish my project as planned and presented in my last application.

Development Of Low-Cost Point-Of-Care Channel Flow Constriction Immunoassays For The Developing World, Neil Anderson, Dr. Adam Woolley

Journal of Undergraduate Research

Biomarkers have a tremendous capacity for use in screening for various diseases, including cancer, diabetes, and bacterial infections. Existing immunoassay methods can detect a broad spectrum of biomarkers. However, they are costly to perform for small numbers of samples and require bulky, expensive instrumentation, making these methods unfit for point-of-care use in the developing world. The focus of my research in the past 10 months has been to help develop a small microfluidic system capable of detecting and quantifying biomarker concentrations with simple, easy-to-read results and that requires little or no technical training before use. Our group has developed and …

Study Of The Thermodynamics Of Chromium(Iii) And Chromium(Vi) Binding To Iron(Ii/Iii)Oxide Or Magnetite Or Ferrite And Magnanese(Ii) Iron (Iii) Oxide Or Jacobsite Or Manganese Ferrite Nanoparticles, Steven Luther, Nathan Brogfeld, Jisoo Kim, Jason Parsons

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4±0.9 nm (Fe3O4) and 15.5±0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies …

Förster Resonance Energy Transfer Investigations Of The Structure Of The Immunoglobulin G Class Of Antibody, Michael Kelliher

College of Science and Health Theses and Dissertations

Ensemble and single molecule methods were used to study model systems of 11 base pair and 16 base pair oligonucleotides. From these experiments it was possible to determine the best ensemble analysis method to use, in conjunction with single molecule experiments, to investigate the structure of lgG in solution. To study the interactions within the antigen-binding fragments (Fab), the binding sites were labeled with a FRET pair. Single molecule fluorescence measurements on the antibody indicate minimal FRET occurring between the dye pair suggesting the distance is too large to be measured using single molecule FRET. Ensemble and single molecule FRET …

Miniaturized Electrostatic Ion Beam Trap Mass Analyzer, Junting Wang

Theses and Dissertations

The electrostatic ion beam trap (EIBT) was designed by D. Zajfman during the previous decade. This ion trap combines many properties of the Fourier-transform ion cyclotron resonance (FTICR) mass analyzer and time-of-flight (TOF) mass analyzer. There are several advantages for the electrostatic ion beam trap. First, large mass-to-charge particles in an electrostatic field could be easier to analyze. Second, there is a folded flight path, which could make the mass analyzer smaller compared to conventional TOF mass analyzer. This principle of operation of this ion trap is analogous to an optical resonator. The ions are trapped in a voltage valley …

Inhibition Of Fast Axonal Transport By Pathogenic Sod1 Involves Activation Of P38 Map Kinase, Gerardo Morfini, Daryl Bosco, Hannah Brown, Rodolfo Gatto, Agnieszka Kaminska, Yuyu Song, Ashutosh Tiwari, Et. Al.

Department of Chemistry Publications

Dying-back degeneration of motor neuron axons represents an established feature of familial amyotrophic lateral sclerosis (FALS) associated with superoxide dismutase 1 (SOD1) mutations, but axon-autonomous effects of pathogenic SOD1 remained undefined. Characteristics of motor neurons affected in FALS include abnormal kinase activation, aberrant neurofilament phosphorylation, and fast axonal transport (FAT) deficits, but functional relationships among these pathogenic events were unclear. Experiments in isolated squid axoplasm reveal that FALS-related SOD1 mutant polypeptides inhibit FAT through a mechanism involving a p38 mitogen activated protein kinase pathway. Mutant SOD1 activated neuronal p38 in mouse spinal cord, neuroblastoma cells and squid axoplasm. Active p38 …

Evolution Of Magnetic Interactions In A Pressure-Induced Jahn-Teller Driven Magnetic Dimensionality Switch, S Ghannadzadeh, J S. Moller, P A. Goddard, T Lancaster, F Xiao, S J. Blundell, A Maisuradze, R Khasanov, Jamie L. Manson, S W. Tozer, D Graf, J A. Schlueter

Chemistry and Biochemistry Faculty Publications

We present the results of high-field magnetization and muon-spin relaxation measurements on the coordination polymer CuF2(H2O)(2)(pyrazine) in pressures up to 22.5 kbar. We observe a transition from a quasi-two-dimensional to a quasi-one-dimensional antiferromagnetic phase at 9.1 kbar, driven by a rotation of the Jahn-Teller axis. Long-range antiferromagnetic ordering is seen in both regimes, as well as a phase separation in the critical pressure region. The magnetic dimensionality switching as pressure is increased is accompanied by a halving of the primary magnetic exchange energy J and a fivefold decrease in the ordering temperature T-N. J decreases gradually with pressure in the …

Single-Step Electrochemical Functionalization Of Double-Walled Carbon Nanotube (Dwcnt) Membranes And The Demonstration Of Ionic Rectification, Xin Zhan, Ji Wu, Zhiqiang Chen, Bruce J. Hinds

Chemistry Faculty Publications

Carbon nanotube (CNT) membranes allow the mimicking of natural ion channels for applications in drug delivery and chemical separation. Double-walled carbon nanotube membranes were simply functionalized with dye in a single step instead of the previous two-step functionalization. Non-faradic electrochemical impedance spectra indicated that the functionalized gatekeeper by single-step modification can be actuated to mimic the protein channel under bias. This functional chemistry was proven by a highly efficient ion rectification, wherein the highest experimental rectification factor of ferricyanide was up to 14.4. One-step functionalization by electrooxidation of amine provides a simple and promising functionalization chemistry for the application of …

Identification And Differentiation Of Tier 1 Bacterial Agents Using Gas Chromatography-Mass Spectrometry, Dan Li

Theses and Dissertations

A simple method was developed for detection and differentiation of five Tier 1 bacterial agents, including Bacillus anthracis, Francisella tularensis, Yersinia pestis, Burkholderia pseudomallei and Burkholderia mallei as well as their closely related near neighbors by gas chromatography-mass spectrometry (GC-MS). Generally, different classes of compounds can be used as biomarkers for biowarfare agent detection, including nucleic acids (i.e., DNA or RNA), proteins (i.e., antibodies), carbohydrates (i.e., sugars), lipopolysaccharides, lipids (i.e., fatty acids) and small molecules. One-step thermochemolysis (TCM) was developed to provide GC-MS detectable biomarker signatures, including sugars, fatty acids and small molecules. Solid phase micro-extraction (SPME) was used for …

State Transformations And Ice Nucleation In Amorphous (Semi-) Solid Organic Aerosol, K. J. Baustian, M. E. Wise, E. J. Jensen, G. P. Schill, M. A. Freedman, M. A. Tolbert

CUP Faculty Research

Amorphous (semi-)solid organic aerosol particles have the potential to serve as surfaces for heterogeneous ice nucleation in cirrus clouds. Raman spectroscopy and optical microscopy have been used in conjunction with a cold stage to examine water uptake and ice nucleation on individual amorphous (semi-)solid particles at atmospherically relevant temperatures (200–273 K). Three organic compounds considered proxies for atmospheric secondary organic aerosol (SOA) were used in this investigation: sucrose, citric acid and glucose. Internally mixed particles consisting of each organic and ammonium sulfate were also investigated.

Results from water uptake experiments followed the shape of a humidity-induced glass transition (T …

Overview Of The Recent Fda Process Validation Guidance For Medicinal Product Development And Manufacture, Nuala Calnan (Editor)

Conference Papers

This conference paper presents an overview of the recently published FDA Process Validation Guideline for the development and manufacture of medicinal drug products. It discusses the impacts of conducting life cycle based validation activities and highlights the future challenges in meeting the ongoing 'Continued Process Validation' (CPV) expectations of the regulator. It also presents the latest information on the EU draft Process Validation Guidance - due for publication in late 2013 / 2014.

Bacterial Spores Remain Viable After Electrospray Charging And Desolvation, Sara Nielson Pratt

Theses and Dissertations

The electrospray survivability of B. subtilis spores and E. coli was tested in atmospheric mobility experiments. E. coli did not survive electrospray charging and desolvation, but B. subtilis did. Experimental conditions ensured that any surviving bacteria were charged, desolvated, and de-agglomerated. B. subtilis was also found to survive both positive and negative electrospray and subsequent introduction into vacuum conditions. Attempts were made to measure the charge distribution of viable B. subtilis spores using electrostatic deflection. From those experiments, it was found that either the spores do not become highly charged under the electrospray conditions used or only spores in a …