Chemistry Commons^™

The Extraction And Coordination Chemistry Of An Organophosphorus Ligand: The Synthesis And Characterization Of Organophosphorus Ligands And Dendrimers Using The Michael-Type Addition, Evelyn M. Bond

Chemistry and Chemical Biology ETDs

In chapter 1, the liquid/ liquid extraction of americium (III) from nitric and hydrochloric acid solutions with chloroform solutions of 2, 6 bis[(diphenylphosphino)methyl]pyridine N, P, P' trioxide (ENOPOPO) is examined. Americium (III) is efficiently extracted from aqueous solutions at high nitric acid concentrations (D_Am > 3000 at 6 M HNO₃) and can be totally back extracted from the organic phrase at 0.01 M HNO_3. The ligand dependency data suggest that two ligand molecules are coordinated to the americium. From hydrochloric acid solutions, ENPOPO exhibits modest extraction ability for americium (III) (D_Am = 2.2 at 5 M …

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 …

Single Crystal Raman Spectra Of 1,2,4,5-Tetrabromobenzene: Calculational And Experimental Assignment Of The Internal Modes, K.M. White, Craig J. Eckhardt

Craig J. Eckhardt Publications

A detailed study of the fundamental internal modes of the 1,2,4,5-tetrabromobenzene crystal has provided assignments of Raman-active modes consistent with polarized single-crystal measurements. A normal-mode calculation based on a valence force field derived from brominated and chlorinated benzenes is found to be in excellent agreement with the assignments. Additional bands arising from anharmonic interactions of the fundamentals are also assigned.

The 5s Rrna Loop E: Chemical Probing And Phylogenetic Data Versus Crystal Structure, Neocles B. Leontis, Eric Westhof

Chemistry Faculty Publications

A significant fraction of the bases in a folded, structured RNA molecule participate in noncanonical base pairing interactions, often in the context of internal loops or multi-helix junction loops. The appearance of each new high-resolution RNA structure provides welcome data to guide efforts to understand and predict RNA 3D structure, especially when the RNA in question is a functionally conserved molecule. The recent publication of the crystal structure of the "Loop E" region of bacterial 5S ribosomal RNA is such an event [Correll CC, Freeborn B, Moore PB, Steitz TA, 1997, Cell 91:705-712]. In addition to providing more examples of …

Structure And Lattice Dynamics Of Dipolarly Disordered 2,3-Dimethylanthracene Crystals, M. Dörr, H. Gerlach, J. Kalus, N. Karl, M. Monkenbusch, I. Natkaniec, U. Schmelzer, W. Schmidt, John J. Stezowski, P. Vorderwisch, M. Warth

John J. Stezowski Publications

2,3-dimethylanthracene (2,3-DMA, C₁₆H₁₄) crystallizes in a pseudocentrosymmetric triclinic lattice with two molecules per unit cell showing dipolar structural disorder of the acentric molecules. Using powder samples the amplitude weighted phonon density of states was measured by inelastic incoherent neutron scattering for different degrees of deuteration. The differences in the resulting spectra can be explained by changes of the dynamics of the molecular bodies or the methyl side groups. By the method of inelastic coherent neutron scattering phonon dispersion curves were determined. The phonon lines are broad even at low temperatures; this fact is supposed to be …

Folding Under Inequilibrium Conditions As A Possible Reason For Partial Irreversibility Of Heat-Denatured Proteins: Computer Simulation Study, Sergey A. Potekhin, Evgenii L. Kovrigin

Chemistry Faculty Research and Publications

Using computer simulations we have studied possible effects of heating and cooling at different scan rates on unfolding and refolding of macromolecules. We have shown that even the simplest two-state reversible transition can behave irreversibly when an unfavorable combination of cooling rate, relaxation time and activation energy of refolding occurs. On the basis of this finding we suppose that apparent irreversibility of some proteins denatured by heat may result from slow relaxation on cooling rather than thermodynamic instability and/or irreversible alterations of the polypeptide chain. Using this kinetic reversible two-state model, we estimated the effects of the scan rate and …

Graft Copolymerization Of Methacrylic Acid, Acrylic Acid And Methyl Acrylate Onto Styrene–Butadiene Block Copolymer, David D. Jiang, Charles Wilkie

Chemistry Faculty Research and Publications

Methyl acrylate, methacrylic acid, and acrylic acid have been graft copolymerized onto styrene–butadiene block copolymer. All three monomers react through the macroradical interacting with the double bond of butadiene. The site of reaction has been established by infrared spectroscopy. For methyl acrylate every unit of the styrene–butadiene block copolymer is grafted but only a small fraction is grafted when the acids are used. The difference apparently lies in the fact that the reaction with the ester is homogeneous while with the acids the reactions are heterogeneous.

Determination Of The N-Terminal Amino Acid Residues On Polypeptides In Secondary Wastewaters, Edward L. Creecy

Chemistry & Biochemistry Theses & Dissertations

The N-terminal amino acid residues on polypeptides and proteins were determined in wastewaters prior to chlorination. The terminal amino groups'ere first derivatized with the well known derivatizing agent dansyl chloride, and then the resulting dansyl amino acid hydrolyzed from the peptide chain by a propionic acid/ hydrochloric acid mixture. The resulting dansyl amino acids were then separated and detected using reversed phase high performance liquid chromatography with fluorescence detection. The majority of N-terminal residues detected were the more polar amino acids. Concentrations ranged from 1 x 10^-10 to 3 x 10^-7 moles/liter. It is suggested that the shorter …

Interleukin (Il)-1 Receptor-Associated Kinase (Irak) Requirement For Optimal Induction Of Multiple Il-1 Signaling Pathways And Il-6 Production, Palanisamy Kanakaraj, Peter H. Schafer, Druie E. Cavender, Ying Wu, Karen Ngo, Patrick F. Grealish, Scott A. Wadsworth, Per A. Peterson, John Siekierka, Crafford A. Harris, Wai Ping Fung-Leung

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

Interleukin (IL)-1 is a proinflammatory cytokine with pleiotropic effects in inflammation. IL-1 binding to its receptor triggers a cascade of signaling events, including activation of the stress-activated mitogen- activated protein (MAP) kinases, c-Jun NH2-terminal kinase (JNK) and p38 MAP kinase, as well as transcription factor nuclear factor κB (NF-κB). IL-1 signaling results in cellular responses through induction of inflammatory gene products such as IL-6. One of the earliest events in IL-1 signaling is the rapid interaction of IL-1 receptor-associated kinases, IRAK and IRAK-2, with the receptor complex. The relative roles of IRAK and IRAK-2 in IL-1 signaling pathways and subsequent …

Solute-Solvent Pair Distribution Functions In Highly Asymmetric Additive Hard Sphere Mixtures, Douglas Henderson, Kwong-Yu Chan

Faculty Publications

Contact values for the solute-solvent pair distribution function in an additive hard sphere mixture, as computed from the Henderson-Chan (HC) formulas, are compared with the recent Monte Carlo (MC) data and formula of Matyushov and Ladanyi (ML) [J. Chem. Phys. 107, 5815 (1997)]. The agreement is found to be excellent. The negative finding of ML is due to a misprint in one of the HC publications. We find the HC formula to be superior to the ML formula when compared to our MC data [Mol. Phys. 91, 1137 (1997)] for the case where the ratio of diameters is large and …

Reactions Of Oxygen Atoms With Van Der Waals Complexes: The Effect Of Complex Formation On The Internal Energy Distribution In The Products, A B. Mccoy, Michael W. Lufaso, M Veneziani, S Atrill, R Naaman

Chemistry Faculty Research and Scholarship

Reactions of atomic oxygen with complexes containing HCl are investigated and the OH product state distributions are compared to those observed for the corresponding reactions of HCl monomers. In previous studies of reactions of O(3P) with HCl and hydrocarbon complexes, rotationally colder OH product state distributions were observed, when compared to the corresponding reactions of monomers. In contrast, we find that reactions of O(1D) with HCl clusters yield OH rotational distributions that are unaffected by the incorporation of HCl into a van der Waals complex. Quasiclassical trajectories are run on collisions of oxygen with HCl and Ar⋯HCl at 1 eV …

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 …

A Mössbauer Spectral Study Of Tb₂Fe₁₇ And The Tb₂Fe₁₇₋ₓsiₓ Solid Solutions, Dimitri Hautot, Gary J. Long, Peter C. Ezekwenna, Fernande Grandjean, D. P. Middleton, K. H. J. Buschow

Chemistry Faculty Research & Creative Works

The Mössbauer spectra of a series of rhombohedral Tb₂Fe_17-xSi_x solid solutions, with x equal to 0, 1, 2, and 3, have been measured as a function of temperature. Although the spectra of Tb₂Fe₁₇ change substantially upon cooling from 295 to 85 K, it has been possible to fit them with a consistent seven sextet model corresponding to a basal magnetization. The spectral analysis yields reasonable hyperfine parameters and the expected changes with temperature. The resulting weighted average effective iron recoil mass of 66 g/mol and the Mössbauer temperature of 395 K are …

The Effect Of Convection On A Propagating Front With A Liquid Product: Comparison Of Theory And Experiments, B. Mccaughey, John A. Pojman, C. Simmons, V.A. Volpert

Faculty Publications

This work is devoted to the investigation of propagating polymerization fronts converting a liquid monomer into a liquid polymer. We consider a simplified mathematical model which consists of the heat equation and equation for the depth of conversion for one-step chemical reaction and of the Navier-Stokes equations under the Boussinesq approximation. We fulfill the linear stability analysis of the stationary propagating front and find conditions of convective and thermal instabilities. We show that convection can occur not only for ascending fronts but also for descending fronts. Though in the latter case the exothermic chemical reaction heats the cold monomer from …

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 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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In-Situ Raman Spectroscopic Study Of The Oxidation And Reduction Of Ag Electrode In Na2So4, Yan-Xia Chen, Kai-Qi Huang, Zhong-Qun Tian

Journal of Electrochemistry

In-situ Raman spectroscopy combined with cyclic voltammogram measurements was used to investigate formation of oxygen species at Ag electrode surfaces during the oxidation and reduction process in 0.1 mol/L Na₂SO₄ solution. The time dependent Raman spectra show that at potentials positive of 0.2 V, adsorption of oxygen atom occurs, while at the potentials positive of 0.4 V, some oxygen atoms migrate into subsurface of the Ag electrode and the other form strongly bound oxygen on the surface through chemical bond. At the same potentials, part of the silver atoms are oxidized and form Ag₂SO_{4 …}

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.

Study Of The Mechanisms Of The Electrochemical Reactions Of The Soluble Polyimides, Ying Zhu, Wei Xing, Hui Zhao, Gui-Zheng Shi, Yue-Sheng Li, Meng-Xian Ding, Hui Yang, Tian-Hong Lu

Journal of Electrochemistry

For the first time, the electrochemical behaviors of the three soluble polyimides were studied in the organic and aqueous solutions. It was found that the electrochemical behaviors of PI in the organic solutions are significantly different from that in the aqueous solution. Using the IR spectroscopy and semi-empirical molecular orbital calculation and combining the results of the electrochemical measurements, the mechanisms of the electrochemical reactions of polyimides were demonstrated.

A Novel Pt(Ir) Plated Stainless Steel Electrode, Jing-Ying Shi, Xiu-Feng Xiao, Ze-Shan Zhu, Xi Zheng, Yan-Zhen Chen, Wen-Yun Hu

Journal of Electrochemistry

A novel Pt(Ir) plated stainless steel electrode have been developed, to be applied underpotential deposition and anchor effect. The electrode is provided with the excellent electrochemical characteristic, lt is possible to use the matter as micro-sensor.

Study Of Charged Property On The Interface Of Porous Membrane Of Anodized Aluminum, Ya-Fei Kuang, Ling Wang, Fei Hu

Journal of Electrochemistry

Using electrodialytic method, the relation between the pH value of tested solution and the ζ potential of porous anodized aluminum membrane, which was separated by reverse electrolysis from aluminum substrate, has been investigated. The following results can be obtained in 1.0×10^-2 mol/L KCl solution: The pH_IEP (isoelectric potential) of the porous membrane is equal to 9.20. In the range of 2.00

Studies On The Transport Properties Of Zn2+ In The Zn/V2O5 Secondary Battery With Aqueous Medium, Jia-Hong Zhou, Kuan-Hong Xue, Gu-Ping Pan

Journal of Electrochemistry

The transport properties and the reaction mechanism of Zn²⁺ in the cathode material of Zn/V₂O₅ secondary battery with aqueous medium were studied by use of intermittent titration experiments and X-Ray diffraction analysis. The relations of some kinetic parameters to the discharge depth were discussed. The results of the experiments show that the cathodic discharge reaction is an intercalation process.

An Investigation On Galvanic Corrosion Behavior Of Co-Cr-Mo Alloy And Ti-6al-4v Alloy, Zhi-Jun Bai, Yin-Shun Wu, Tian-Cheng Zhang

Journal of Electrochemistry

The combination of Co-Cr-Mo alloy and Ti-6Al-4V alloy is widely used as total hip prostheses. The objective of this work is to quantify the possibility of the acceleration of corrosion due to the galvanic effect. Electrochemical tests based on mixed potential and protection potential theories were used to study the galvanic corrosion behavior of coupling these alloys. The results indicated that the galvanic potential between two alloys always was in the passive potential zone of the isolated alloy respectively, and that the galvanic current of the couple is same as the corrosion current of isolated alloy under passive state. The …

Investigation Of Pb/Pb2+ And Polypyrrole Electrodes By Use Of Ac Electrochemical-Thermal Method, Ji-Hua Zhuang, Jie Zhang, Liang-Jun Dong, Hong Xie, Zhi-Yu Jiang

Journal of Electrochemistry

The values of entropy change for Br^-/Br₂ and Pb/Pb²⁺ electrode reactions were measured by use of the ac electrochemical-thermal method. The influence of alkaline pretreatment on the electrochemical behavior for a polypyrrole electrode was also investigated by this method. It was found that after alkaline pretreatment the eletrochemical activity of polypyrrole electrode was decreased obviously, but it kept partly electrochemical-thermal characteristic as same as that before pretreatment.

Electrode Process Of Lithium Ions On Aluminum Electrode In Molten Licl-Kcl, Shu-Zhen Duan, Cong-Sheng Guan, Qing-Rong Shi, Xin-Dong Wang

Journal of Electrochemistry

The Deposition mechanism of Lithium on aluminium electrode was studied by using linear sweep voltammetry and potential step method. The formation of α-solid solution was controlled by the diffusion of lithium within the aluminium substance. The formation of β-LiAl alloy was limited by the rate of forming the alloy at the legining, and by diffiusion of lithium through the β- LiAl alloy layer was limited by the rate of forming the alloy at the begining, and by the diffusion of lithium through the β-LiAl alloy later. Neucleation polarization for the formation of β-LiAl alloy was observed. This polarization is an …

Molecular Inclusion Of Cyclodextrin Polymer And Its Application To Enzyme Electrodes, Hui-Huang Wu, Bao-Zhang Wu

Journal of Electrochemistry

The inclusion complexation of α-cyclodextin prepolymer host with benzoquinone guest was studied by voltametry. The spectroscopic measurements show that the polycondensation of CD with glutaric dialdehyde forms the polymer (PCD) with pending carbonyl, the latter brings about covalent immobilisation of glucose oxidase (GOD) to polymer chains. Owing to the inclusion complexation of CD, the benzoquinone(BQ) as mediator of GOD can be collected in the enzyme-containing PCD membrane, resulting in high concentration of BQ in the membrane while decreasing its amount in solution. TTF was tested to prepare the immobilised enzyme together with mediator in PCD. The enzyme loading in PCD …

Study On The Substitution Of Chromium Alloy Electroplating From Trivalent Plating Bath For The Hard Chromium Plating, Hui-Dong Li, Min Li, Hui-Qi Li

Journal of Electrochemistry

Recently, a vast amount of exploring experiments have been made to solve many deadly defect of existing trivalent chromium plating processes and promote to finally substitute the trivalent chromium for the hexvalent chromium plating. Technical scheme which we substitute the amorphous chromium alloy deposition for the pure chromium is determined step by step and process of amorphous Cr-Fe-C alloy plating from trivalent chromium plating bath has been developped successfully. The deposition maintains standard of traditional hexvalent chromium deposition in properties of wear-resistance and corrosive wear resistance. Moreover, it completely eliminates serious enviromental pollution and has certain advantages of technological property …

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. …