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Bubble Fractionation Of Enantiomers From Solution Using Molecularly Imprinted Polymers As Collectors, Daniel W. Armstrong, J. M. Schneiderheinze, Y. S. Hwang, B. Sellergren

Chemistry Faculty Research & Creative Works

Adsorptive bubble separation methods have been used to enrich components from both heterogeneous and homogeneous solutions. These methods are particularly effective for processing large solution volumes at low cost Previous work demonstrated that chiral, surface-active collectors could be used to enrich enantiomers from homogeneous solution in a foam fractionation process. In a significant extension of this work, the use of highly selective molecularly imprinted polymers (MIPs) and heterogeneous solutions for the bubble flotation of enantiomers was evaluated. The high selectivity and ease of recycling of the MIP make this a potentially powerful approach for process-scale separations from large-volume bulk solutions. …

Direct Voltammetric Observation Of Redox Driven Changes In Axial Coordination And Intramolecular Rearrangement Of The Phenylalanine-82-Histidine Variant Of Yeast Iso-1-Cytochrome C, Benjamin A. Feinberg, Xiangjun Liu, Michael D. Ryan, Abel Schejter, Chongyao Zhang, Emanuel Margoliash

Chemistry Faculty Research and Publications

Direct square-wave and cyclic voltammetric electrochemical examination of the yeast iso-1-cytochrome c Phe82His/Cys102Ser variant revealed the intricacies of redox driven changes in axial coordination, concomitant with intramolecular rearrangement. Electrochemical methods are ideally suited for such a redox study, since they provide a direct and quantitative visualization of specific dynamic events. For the iso-1-cytochrome c Phe82His/Cys102Ser variant, square-wave voltammetry showed that the primary species in the reduced state is the Met₈₀-Fe²⁺-His₁₈ coordination form, while in the oxidized state the His₈₂-Fe³⁺-His₁₈ form predominates. The addition or removal of an electron to the …

Development And Field Testing Of Pulse Introduction Membrane Extraction (Pime) For Measurement Of Ground Water Contamination, Anthony San Juan

Theses

VOCs are a class of aromatic and aliphatic compounds with a variety of functional groups, and are in general detrimental to human health even at trace levels. Conventional analysis of VOCs in groundwater usually involves sampling at site followed by laboratory analysis. This results in long turn around times, high cost and also errors associated with sample preservation during transportation and storage. In order to address these problems, a field portable instrument referred to as Pulse Introduction Membrane Extraction (PIME) has been developed for monitoring trace level halogenated organic contaminants in ground water. A membrane extraction approach has been used, …

Prospects Of Electrochemistry, Katsumi Niki

Journal of Electrochemistry

No abstract provided.

Direct Electrochemical Reaction Of Cytochrome C At The Poly (Ethylene Oxide) Film Modified Gold Electrodes, Xiao-Gang Qu, Gong-Quan Sun, Hui Yang, Tian-Hong Lu

Journal of Electrochemistry

In this paper, the direct electrochemical reaction of cytochrome c was sudied at the poly (ethylene oxide) film modified gold electrodes. It was found the PEO is a good promoter for the electrochemical reaction of cytochrome c, and the reversibility of reaction of cytochrome c was found to depend on the molecular weight of PEO and the morphology of the PEO films.

Ac Impedance Study Of The La0.8Sr0.2Mno3/Ysz Electrode, Shi-Zhong Wang, Yi Jiang, Ya-Hong Zhang, Jing-Wang Yan, Wen-Zhao Li

Journal of Electrochemistry

Electrochemical reaction of oxygen on the La_0.8Sr_0.2MnO₃/YSZ electrode has been investigated in detail with AC impedance. The results demonstrated that the rate determining step(rds) of the reaction varies with the temperature, oxygen partial pressure and overpotential applied. At open circuit potential, the rds is the dissociative adsorption of oxygen on the LSM surface. A large number of electron holes are generated at high anodic overpotentials, while oxygen vacancies are formed at high cathodic overpotentials. The formation of the electron holes results in the electronic conduction of the YSZ electrolyte and the extension of the …

The Hydrogen Evolution Reaction On The Hydrogen Storage Alloy Electrode, Shi-Gang Lu, Qun Li, Qing-Guo Liu, Chun Lu, Bing Dang, Han-Xi Yang

Journal of Electrochemistry

The hydrogen evolution reaction was studied in 1 mol/L KOH solution on the hydrogen storage alloy Mm(NiCoMnAl)₅ electrode using open circuit potential decay and ac impedance technique. The reaction was found to proceed by the Volmer(discharge)-Tafel(recombination)mechanism. The measured overpotential η can be subdivided into two components η 1 and η 2 corresponding to the elementary Volmer and Tafel reaction. The Faradaic impedance was analyzed and characterized by the Volmer reaction. Then the exchange current density was evaluated . It was founded that the activity of hydrogen storage alloy electrode for the hydrogen evolution reaction was similar to that of …

Modification Of Carbon Anode Materials Of Lithium-Ion Secondary Battery, Yuping Wu, Chun-Rong Wan, Chang-Yin Jiang, Jiang-Iun Li

Journal of Electrochemistry

In this paper, the latest research work on modification of carbon anode materials of lithium ion secondary battery is reviewed. Modification methods include: incorporation of nonmetal elements such as boron, silicon, nitrogen, phosphorus and sulfur, metal elements such as potassium, aluminum, gallium and transitional metal elements such as vanadium, nickel, cobalt, copper and iron and surface treatment such as oxidation and formation of surface layer. Since these methods can affect the carbon materials' electronics state, crystal structure and surface structure, the electrochemical properties of the carbon materials could probably be improved. Besides, mechanisms for lithium storage in carbonaceous materials are …

Formation And Effect Of Tribo Cell For Fe Cr Alloy, Dong-Bai Sun, Tao Li, Hong-Ying Yu, De-Ji Yang

Journal of Electrochemistry

The micro galvanic corrosion of 1Cr18 alloy and its effects on the triboelectrochemical behavior were investigated and analyzed in this article. It is shown that the micro galvanic corroson is due to the electrochemical inhomogenity on the surface of the alloy during the friction process. Like galvanic corrosion,the micro galvanic corrosion behaviors are greatly affected by the area ratio of unrubbed to rubbed surface.The load effects on electrochemical behavior of 1Cr18 alloy are also attributed to existence of electrochemical inhomogenity on the surface of materal.

Lithiun Insertion In Carbon Nanotubes, Guo-Tao Wu, Chun-Sheng Wang, Zhong-Fu Qi, Wenz-Hu Li

Journal of Electrochemistry

Carbon nanotubes were produced by chemical vapour deposition(CVD) of acetylene under hydrogen gas.The reversible specific capacity of carbon nanotubes is up to 700 mAh/g, much higher than the theoretical specific capacity of graphite(372 mAh/g).After twenty charge/discharge cycles,the discharge capacity of carbon nanotube anode still maintains 65.3% of its original discharge capacity . Besides, the charge/discharge efficiency of carbon nanotube in the first charge/discharge cycle was found to improve from 42.6% up to 55.9% by coating carbon nanotubes with copper.

External Transducing Measurement Of The Internal Pressure In Sealed Battery By Resistance Strain Gauge, Han-Xi Yang, Rong-Hui Hu, Xin-Ping Ai, Cong-Zhi Yang, Sheng-Xian Li

Journal of Electrochemistry

A novel method to monitor dynamically the internal pressure of sealed battery with no damage of the battery by using of resistance strain measurement technique is presented. This technique employs the resistence strain gauges in touch of the battery case and to detect the minimal change in the battery deformation due to the increasing internal pressure, electrode expantion or intrenal temperature rise. Application of the technique for the study of the effects of the battery processing factors on the battery performance is described taking Ni MH battery as example.

Photoelectrochemical Studies On Nanoporous Tio2/Pan Film Electrode, Min-Sheng Liu, Yan-Zhong Hao, Xue-Bin Qiao, Mai-Zhi Yang, Sheng-Min Cai

Journal of Electrochemistry

The photon to electricity conversion process of nanoporous TiO₂/PAn film electrode was studied in electrolytes with and without redox couple by using the photocurrent action spectra and potential dependence of photocurrent. It is concluded that the nanoporous TiO₂/PAn film electrode has a structure of duplex n type semiconductor layers. The band gap of PAn film is 2.88eV.The TiO₂ nanoporous film electrode modified by PAn can extend the range of optical absorption into visible and infrared region and effectively increase the photocurrent in the visible and infrared region. The photocurrent threshold shifts to>600nm and conversion …

Studies On The Electrode Kinetics Of Electrooxidation Of Mn2+, Wan-Li Hu, Tong Su, Wei Guo, Ding Zhou

Journal of Electrochemistry

The mechanism of electrooxidation of MnSO₄ on Pb Sb As alloy anode was investigated by using rotating disc electrode technique. The results shown that the conditional standard potential of Mn(Ⅲ)/Mn(Ⅱ)in 40% H₂SO₄ is 0.886 4 V.The rate controlling step of electrode process is mixed controlled by charge transfer and diffusion.

Electrochemical Behavior Of Chemically Prepared Ring-Substituted Polyanilines, Li-Zong Dai, Hui-Huang Wu

Journal of Electrochemistry

Polyaniline (PAn) has been known as a promising conducting polymer for technological applications. In research work elecrochemically synthesized PAn has been frequently used since electropolymerization is convenient to prepare the polymer film with controllable thickness or dopingon electrodes. However , the processibility of elecrosynthesized PAn is too poor to produce largearea devices because of its insolubility and infusibility. Recently, therefore, chemical polymerization has attracted a considerable attentionfl-3],  especially suitably derivatized ring substituted (e.g. alkyl or alkoxy) polyanilines have been synthesized, and their appreciable solubility in commonorganic solvents enable the preparation of film on industrial scale by casting. Moreover, emulsionpolymerization reduces …

Studies On The Preparation Of Nanophase Electrode Materials And Its Electrochemical Properties(Ⅲ)—Performance Of Nm-Γ-Mno2 Obtained By Microemulsion Method, Ling Liu, Xi Xia

Journal of Electrochemistry

A nanophase MnO₂ was synthesized using w/o microemulsion as reation media, The most favorable experiment conditions for the preparation of nm MnO₂ were researched. XRD,TEM,AC impedance, cyclic voltammetry etc. examinations were used to characterize the sample comparison with the classical MnO₂ (I.C.No.1EMD,electrolytic manganese dioxide). Sample shows that the crystal styucture of the synthesized samples are mainly γ-MnO₂, with average particle size in the nanometer as shown by TEM. It was found that the discharge capacity of nm MnO₂ obtained is significantly higher than that of the I.C.No.1 EMD.

Electrooxidation Of Benzene To Benzoquinone In A Packed Bed Reactor, Xin-Sheng Zhang, Ping Ding, Ying-Chun Dai, Wei-Kang Yuan

Journal of Electrochemistry

A packed electrode reactor was used to oxidize to benzoquinone. Anode bed of the reactor has a size of 10～30 mm×450 mm×50 mm(thickness×length×width),and was packed porous lead alloy. A dispersion of benzene in 1 mol/L aqueous sulfuric acid was passed through the reactor. Current efficiency for benzoquinone generation is 62.9% at optimal operating condition: velocity of electrolyte flow, 0.19 ms ^-1 ;current, 10 A; thickness of anode bed, 10 mm, and percentage of benzene, 24%.

Study Of Proton Exchange Membrane Fuel Cells(Pemfc), Shan-Hai Ge, Bao-Lian Yi, Hong-Fen Xu, Ming Han, Zhi-Gang Shao

Journal of Electrochemistry

The electrode kinetic parameters for proton exchange membrane fuel cells(PEMFC) were investigated by measuring the relations of cell potential and current density. An experimental stack of PEMFC which can be operated at E cell =0.7V, I =0.55A/cm² steadily is presented, and the effects of electrode structure and operation conditions such as temperature, pressure, humidification, flow rate on the performance of PEMFC are discussed.

On-Road Remote Sensing Of Automobile Emissions In The Chicago Area: Year 1, Peter J. Popp, Gary A. Bishop, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

Improvement Of Epa Method 8330: Complete Separation Of Explosives Using A Two Phase Approach, Michael J. Lang

Masters Theses

A wide range of primary and secondary contaminants is found in environmental matrices containing explosive residues. HPLC methodology for the detection of explosive is now standardized in EPA Method 8330, and represents the most common method currently used for explosive analysis. However, co-elution of some of the analytes occurs even using method 8330. As a result, explosive analysis using HPLC have required the use of a confirmation column in an additional analysis step.

In the current work, all of the compounds in the EPA 8330 explosives list were resolved using a single HPLC separation. While the EPA 8330 HPLC conditions …

Orientational Susceptibility And Elastic Constants Near The Nematic-Isotropic Phase Transition For Trimers With Terminal-Lateral-Lateral-Terminal Connections, Daeseung Kang, Milind P. Mahajan, Rolfe G. Petschek, Charles Rosenblatt, Chaobin He, Puwei Lu, A.C. Griffin

Faculty Publications

Magnetically induced Freedericksz measurements were performed in the nematic liquid crystal phase to extract the elastic constants of a terminal-lateral-lateral-terminal trimer, i.e., a trimer in which the connections to the first and third mesogens are at the end of the mesogen and both attachments to the central mesogen are lateral. Polymeric liquid crystals based on this unit have negative Poisson ratios. Additionally, electric field Kerr measurements were performed in the isotropic phase to extract the orientational susceptibility. The elastic constants were found to be similar to values obtained for typical monomers, albeit with a slightly enhanced ratio K-33/K-11 and reduced …

40th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 40th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 25 - August 1, 1998.

Covalently Functionalized Nanotubes As Nanometer-Sized Probes In Chemistry And Biology, Stanislaus S. Wong, Ernesto Joselevich, Adam T. Woolley, Chin Li Cheung, Charles M. Lieber

Barry Chin Li Cheung Publications

Carbon nanotubes combine a range of properties that make them well suited for use as probe tips in applications such as atomic force microscopy (AFM)^{1, 2, 3}. Their high aspect ratio, for example, opens up the possibility of probing the deep crevices⁴ that occur in microelectronic circuits, and the small effective radius of nanotube tips significantly improves the lateral resolution beyond what can be achieved using commercial silicon tips⁵. Another characteristic feature of nanotubes is their ability to buckle elastically^{4, 6}, which makes them very robust while limiting the maximum force that is …

The Synthesis And Characterization Of A Porphyrin Oligomer As A Potential Antenna For Light Harvesting Solar Cells, Tristan Timothy Jenkins

Dissertations and Theses

Mankind's attempts to harvest the sun have resulted in photocells with about 15% overall energy conversion efficiency. The best of these cells consist of a light-sensitive dye attached to a semiconductor. Absorbed light energy is transferred to the semiconductor via the delivery of an excited electron from the dye. Dye electrons are replenished with a redox solution, coupling the dye to the counter electrode.

This research was the beginning of an exploration into some potential improvements in the cell. First of all, the redox solution is a corrosive liquid, and leaks present a problem. A porphyrin oligomer with a TCPP …

Catalyctic Reduction Of Nitric Oxide By Carbon Monoxide And Copper Loaded Granular Activated Carbon In The Presence Of Oxygen, Kaiwen Ma

Theses

The reduction reaction of nitric oxide (NO) by carbon monoxide (CO), and granular activated carbon (GAC) in the presence and absence of oxygen was studied in a fixed bed catalytic reactor. The conversion of NO as a function of reaction temperature was evaluated for various reductant to NO ratios and space velocities. The results show that oxygen enhanced the NO+CO reaction over copper (Cu) ion exchanged ZSM-5. About 60% NO conversion to nitrogen (N₂) was obtained at 400°C and 2,000 v/v/hr. This result is consistent with the hypothesis that CO is an intermediate in the soot-NO reaction. The …

In Vitro Cytotoxicity Study Of Glutaraldehyde And No-React Treated Bioprosthetic Heart Valves And The Aortic Wall, Roger Ongosi

Theses

Valvular failure due to calcification and leaflet disruption of artificial bioprostheses is still a major concern in valve replacement surgery. Previous studies have shown that Glutaraldehyde, a chemical used in the treatment of artificial valves promotes calcification. In this investigation glutaraldehyde and No-React® treated tissue samples of pericardium, cusp and the aortic wall were tested for cytocompatibility using live mouse fibroblast cultures. The samples were cut into 3 X 3 mm2 washed in phosphate buffered saline solution, transferred into cell culture flask containing cells that had been cultured for 24 hours and incubated at 37 "C in 5 % CO2. …

Electrochemical Preparation Of Rare Earth Functional Materials And Application Of Rare Earth To Electrochemistry, Qi-Qin Yang, Tong-Xiang Ye

Journal of Electrochemistry

The new progress and related mechanism of the electrochemical preparation of rare earth materials (magnets, magnetooptic materials, battery materials, luminescent devices, semiconductors, superconductors) and the application of rare earth to the electrochemical areas (e.g. electroplating, corrosion, electrosynthses) have introduced.

Studies On Impedance Of Acid-Copper Electroplating System, Wen Deng, Zhao Liu, Xiang-Min Lin, He-Tong Guo

Journal of Electrochemistry

The impedance characteristics of elementary solution (0.3 mol/L CuSO₄+1.94 mol/L H₂SO₄) and that with the addition of 60 mg/L Cl^-, 300 mg/L OP-21, 30 mg/L PEG, 10 mg/L 2thiazolinyldithiopropane sulfate (self-synthesized additive) are investigated and interpreted in terms of equivalent circuit. The results indicated: (1) Cl^- ion can increase cathodic polarization. (2) A twostep reaction mechanism corresponds to Cu^₂₊ reduction, that is: Cu^₂₊→Cu⁺, Cu⁺→Cu(adsorption)→Cu(lattice), Cu^₂₊ react in different forms of complex ion in sulfuric acidcupric sulfate solution with or without Cl^- ion. …

Application Of Electrochemical Process To Recycling Waste Water From Flotation Of Phosphate Ores, Shi-Xin Yu, Wen Sun

Journal of Electrochemistry

The waste water from flotation of phosphate ores can be used to recycling by electrochemical process. The suitable factors of electrochemical process is made by measuring ζ potential and transmittance of the waste water in modified way.

Studies Of Surface Alloy As High Efficient Electrocatalyst For Glyoxylic Acid Synthesis, Sheng-Pei Chen, Sheng-Qing Xia, Shi-Gang Sun

Journal of Electrochemistry

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Influences Of Ptfe On Electrochemical Properties Of Foam-Type Ni(Oh)2 Electrodes, Zhen Zhou, Jie Yan, Xian-You Wang, Jin Lin, Hua-Tang Yuan, De-Ying Song, Yun-Shi Zhang

Journal of Electrochemistry

Research work was performed for the influences of PTFE on the electrochemical properties of foam-type Ni(OH)₂ electrodes by constant current discharge. CV and EIS method. Experimental results exhibit that the existence of PTFE would decrease the reversibility of electrode reaction and increase the reaction resistance of the electrode; thus lower the discharge potential and capacity, so PTFE should be added as little as possible during the preparation of paste-type electrodes.