Chemistry Commons^™

Phosphorus Sorption In Relation To Soil Grain Size And Geochemical Composition In The Simiyu And Kagera River Basins, Tanzania, R. A. Tamatamah

Tanzania Journal of Science

The phosphorus sorption characteristics of eight surface soil samples representative of the land use and landscape in the Simiyu and Kagera River basins were determined using the Langmuir equation. The Langmuir P adsorption maximum (Cmax) ranged from 109 to 802 mg kg-1, while Langmuir coefficient (K) ranged from 59 to 736 mg L-1. Cmax and were positively correlated to clay content, aluminium (Al), and iron (Fe) and negatively correlated to calcium (Ca). By using stepwise regression, the combination of Al, Fe, clay and Ca predicted more than 94% of the variation in the P sorption capacity of soils samples from …

Petrography And Mineral Chemistry Of The Pelitic And Semi-Pelitic Gneisses Of The Merelani Tanzanite Mining Area, Northeastern Tanzania, E. P. Malisa

Tanzania Journal of Science

Sillimanite/kyanite + K-feldspar + quartz ± garnet + biotite ± Fe-Ti oxide-bearing rocks occur associated with calc-silicate rocks in the Merelani tanzanite mining area north-eastern Tanzania. The whole rock chemistry shows varying rock oxidation ratios, which are reflected in the mineralogical assemblages. Almandine garnet is oxidized to mixtures of hematite, quartz, and hydrous aluminosilicates in oxidized rocks and is absent in highly oxidized rocks. In the latter, ilmenite is oxidized into mixtures of rutile and hematite. Such relatively high temperature alteration/oxidation effects could have occurred with the influx of water. Absence of staurolite in these aluminium-rich rocks is indicative of …

The Mechanism Of Membrane Targeting Of Human Sphingosine Kinase 1, Robert V. Stahelin, Jeong H. Hwang, Jin-Hahn Kim, Zee-Yong Park, Korey R. Johnson, Lina M. Obeid, Wonhwa Cho

Faculty Publications & Research

Sphingosine 1-phosphate is a bioactive sphingolipid that regu- lates cell growth and suppresses programmed cell death. The bio- synthesis of sphingosine 1-phosphate is catalyzed by sphingosine kinase (SK) but the mechanism by which the subcellular localization and activity of SK is regulated in response to various stimuli is not fully understood. To elucidate the origin and structural determi- nant of the specific subcellular localization of SK, we performed biophysical and cell studies of human SK1 (hSK1) and selected mutants. In vitro measurements showed that hSK1 selectively bound phosphatidylserine over other anionic phospholipids and strongly preferred the plasma membrane-mimicking membrane to …

Cu2O(1 1 0) Formation On Co3O4(1 1 0) Induced By Copper Impurity Segregation, S. C. Petitto, Marjorie Langell

Marjorie A. Langell Publications

The surface crystal structure of the Co₃O₄(1 1 0) spinel was characterized by low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES). Well-defined LEED diffraction patterns showed an unreconstructed Co₃O₄(1 1 0) surface in Type A termination, and XPS and Auger indicated the surface to be stoichiometric with octahedral and tetrahedral cation sites occupied by 3+ and 2+ cations, respectively. The experimental lattice parameters of 8.22 Å ± 0.2 Å and 5.50 Å ± 0.2 Å in the (0 0 1) and (1¯ 1 0) directions, respectively, …

(E)-9,10-Dihydro-9-Methyl-9-Nitro-10-(Trinitro­Meth­Yl)Anthracene, Mustafa Arslan, Ronald J. Baker, John Masnovi, Erol Asker

Chemistry Faculty Publications

The title compound, C₁₆H₁₂N₄O₈, was prepared by the photochemical reaction of 9-methyl­anthracene and tetra­nitro­methane in dichloromethane. Intermolecula face-to-face π–π stacking inter­actions are present along the a axis.

Kondo Resonances And Anomalous Gate Dependence In The Electrical Conductivity Of Single-Molecule Transistors, L H. Yu, Z K. Keane, Jacob W. Ciszek, L Cheng, J M. Tour, T Baruah, M R. Pederson, D Natelson

Chemistry: Faculty Publications and Other Works

We report Kondo resonances in the conduction of single-molecule transistors based on transition metal coordination complexes. We find Kondo temperatures in excess of 50 K, comparable to those in purely metallic systems. The observed gate dependence of the Kondo temperature is inconsistent with observations in semiconductor quantum dots and a simple single-dot-level model. We discuss possible explanations of this effect, in light of electronic structure calculations.

Discovery And Characterization Of The Cryptic Psi Subunit Of The Pseudomonad Dna Replicase, Thale C. Jarvis, Amber A. Beaudry, James M. Bullard, Urs Ochsner, H. Garry Dallmann, Charles S. Mchenry

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

We previously reconstituted a minimal DNA replicase from Pseudomonas aeruginosa consisting of α and ϵ (polymerase and editing nuclease), β (processivity factor), and the essential τ, δ, and δ′ components of the clamp loader complex (Jarvis, T., Beaudry, A., Bullard, J., Janjic, N., and McHenry, C. (2005) J. Biol. Chem. 280, 7890-7900). In Escherichia coli DNA polymerase III holoenzyme, χ and Ψ are tightly associated clamp loader accessory subunits. The addition of E. coli χΨ to the minimal P. aeruginosa replicase stimulated its activity, suggesting the existence of χ and Ψ counterparts in P. aeruginosa. The P. aeruginosa χ …

Estimation Of Iron Solubility From Observations And A Global Aerosol Model, Chao Luo, N. M. Mahowald, N. Meskhidze, Y. Chen, R. L. Siefert, A. R. Baker, Anne M. Johansen

All Faculty Scholarship for the College of the Sciences

Mineral aerosol deposition is the dominant source of iron to the open ocean. Soil iron is typically insoluble and understanding the atmospheric processes that convert insoluble iron to the more soluble forms observed over the oceans is crucial. In this paper, we model several proposed processes for the conversion of Fe(III) to Fe(II), and compare with cruise observations. The comparisons show that the model results in similar averaged magnitudes of iron solubility as measured during 8 cruises in 2001–2003. Comparisons show that results of cases including cloud, SO₂ and hematite processing are better than the other approaches used using …

Intrinsic Conformational Preferences Of Substituted Cyclohexanes And Tetrahydropyrans Evaluated At The Ccsd(T) Complete Basis Set Limit: Implications For The Anomeric Effect, Abby Jones Weldon, Trisha L. Vickrey, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

A series of MP2 and CCSD(T) computations have been carried out with correlation consistent basis sets as large as aug-cc-pV5Z to determine the intrinsic equatorial-axial conformational preference of CH 3-, F-, OCH 3-, and OH-substituted cyclohexane and tetrahydropyran rings. The high-accuracy relative electronic energies reported here shed new light on the intrinsic energetics of these cyclic prototypes for the anomeric effect. At the CCSD(T) complete basis set (CBS) limit, the energy of the equatorial conformation relative to the axial position (ΔE CCSD(T)CBC) is -0.75, -0.20, -0.21, and -0.56 kcal mol -1 in methyl-, fluoro-, methoxy-, and hydroxy cyclohexane, respectively, while …

Lead Optimization Of 7-Benzyloxy 2-(4′-Pyridylmethyl)Thio Isoflavone Aromatase Inhibitors, Bin Su, John C. Hackett, Edgar S. Diaz-Cruz, Young Woo Kim, Robert W. Brueggemeier

Chemistry Faculty Publications

Aromatase, the enzyme responsible for estrogen biosynthesis, is a particularly attractive target in the treatment of hormone-dependent breast cancer. The synthesis and biological evaluation of a series of 2-(4′-pyridylmethyl)thio, 7-alkyl- or aryl-substituted isoflavones as potential aromatase inhibitors are described. The isoflavone derivatives demonstrate IC50 values from 79 to 553 nM and compete with the endogenous substrate, androstenedione. Data supporting the ability of these analogs to suppress aromatase enzyme activity in the SK-BR-3 breast cancer cell line are also presented.

11,12-Bis(2,2-Dimethyl­Prop­Yl)-9,10-Dihydro-9,10-Ethenoanthracene, Joseph P. Herres, Mark A. Forman, Kraig A. Wheeler

Faculty Research and Creative Activity

The title compound, C26H32, was retrieved as one of three products from the reaction of tert-butyl­lithium with 11,12-dimethyl­ene-9,10-dihydro­ethenoanthracene and 4,5-diiodo­penta­cyclo­[4.3.0.02,4.03,8.05,7]nonane. The structure shows the expected ethenoanthracene geometry with mol­ecules arranged via van der Waals surfaces.

Oligomeric And Polymeric Bibenzimidazole Based Metal Complexes And Crosslinked Polyethylenimine Based Flame Retardants, Jun Yin

Chemistry & Biochemistry Dissertations - Archive

In Part I, a simple and mild condensation route for the synthesis of novel bibenzimidazole oligomers and polymers is described using methyl 2,2,2-trichloroacetimidate as a key starting material. The dimer, trimer, tetramer, and polymers of bibenzimidazole were synthesized as a new series of potential conjugated chelating ligands for the metallopolymer studies. The polymers show the maximum absorption at around 400 nm. The optical band gap of the polymer is estimated to be 2.68 eV. In Part II, a series of multinuclear Ru complexes containing di-, tetra-, and octa-RuII centers based on the oligomeric bibenzimidazoles were synthesized and characterized. The species …

Exafs Studies Of Bimetallic Ag-Pt And Ag-Pd Nanorods, Debdutta Lahiri, Soma Chattopadhyay, B. A. Bunker, Cm Doudna, Massimo F. Bertino, Frank D. Blum, Akira Tokuhiro, J. Terry

Physics Faculty Research & Creative Works

Nanoparticles of Ag-Pt and Ag-Pd with high aspect ratios were synthesized using a radiolysis method. Gamma rays at dose rates below 0.5 kGy/h were used for irradiation. the nanoparticles were characterized by transmission electron microscopy (TEM), optical absorption spectroscopy and x-ray Absorption Fine Structure (XAFS) spectroscopy. Bright field micrographs show that Ag-Pt nanowires are composed of large particles with diameters ranging from 20-30 nm and joined by filaments of diameter between 2-5 nm. the Ag-Pd nanowires have diameters of 20-25 nm and lengths of 1.5 μm. for XAFS measurements, the Pt L3 edge (11.564 keV), Ag K-edge (25.514 keV) and …

Cloning, Overexpression, Purification And Characterization On N-Terminal Metal Binding Domains 5 And 6 Of Wilsons Disease Protein, David Achila

Masters Theses

Wilsons disease is an autosomal recessive disorder of copper metabolism which results from mutations in the gene encoding for Wilson disease protein (WDP). The cytosolic N-terminus of WDP comprises six metal binding domains each containing a conserved metal binding motif, GMXCXXC. The contribution of these metal binding domains to copper homeostasis is poorly understood. We have cloned, expressed and purified residues 485 to 633 corresponding to N-terminal metal-binding domains 5 and 6 of WDP (WD5-6). Two of the 3 disease causing mutations in the N-terminal metal binding domains of WDP occur one in each of these domains and the two …

Systems For Predicting Pitzer’S Ion-Interaction Model Parameters, Theresa Balderas Obias

Masters Theses

Pitzer's Ion-interaction Model had been widely used in predicting the non-ideal behavior of solution over a wide range of conditions for natural water systems. The model is successful only when there are sufficient parameters available. However, generating these needed parameters requires a great quantity of work and it would be advantageous to be able to predict the Pitzer's parameters for salt systems when there is no data available.

This research entailed the development of ionic radii dependent equations for Pitzer's binary ion-interaction parameters β_MX⁽⁰⁾, β_MX⁽¹⁾, β_MX⁽²⁾, and C^ϕ_MX . …

Multivalued Logic, Neutrosophy And Schrodinger Equation, Florentin Smarandache, Victor Christianto

Branch Mathematics and Statistics Faculty and Staff Publications

This book was intended to discuss some paradoxes in Quantum Mechanics from the viewpoint of Multi-Valued-logic pioneered by Lukasiewicz, and a recent concept Neutrosophic Logic. Essentially, this new concept offers new insights on the idea of ‘identity’, which too often it has been accepted as given. Neutrosophy itself was developed in attempt to generalize Fuzzy-Logic introduced by L. Zadeh. While some aspects of theoretical foundations of logic are discussed, this book is not intended solely for pure mathematicians, but instead for physicists in the hope that some of ideas presented herein will be found useful. The book is motivated by …

M4@Si28 (M=Al,Ga) Metal-Encapsulated Tetrahedral Silicon Fullerene, Yi Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

It is known that silicon fullerenes cannot maintain perfect cage structures like carbon fullerenes. Previous density-functional theory calculations have shown that even with encapsulated species, nearly all endohedral silicon fullerenes exhibit highly puckered cage structures in comparison with their carbon counterparts. In this work, we present theoretical evidences that the tetrahedral fullerene cage Si₂₈ can be fully stabilized by encapsulating a tetrahedral metallic cluster (Al₄ or Ga₄). To our knowledge, this is the first predicted endohedral silicon fullerene that can retain perfectly the same cage structure (without puckering) as the carbon fullerene counterpart (T_{d …}

A Study Of How Precursor Key Concepts For Organic Chemistry Success Are Understood By General Chemistry Students, Patrick Gerard Meyer

Dissertations

This study examines college student understanding of key concepts that will support future organic chemistry success as determined by university instructors. During four one-hour individual interviews the sixteen subjects attempted to solve general chemistry problems. A think-aloud protocol was used along with a whiteboard where the students could draw and illustrate their ideas. The protocols for the interviews were adapted from the Covalent Structure and Bonding two-tiered multiple choice diagnostic instrument (Peterson, Treagust, & Garnett, 1989) and augmented by the Geometry and Polarity of Moleculessingle-tiered multiple choice instrument (Furió & Calatayud, 1996). The interviews were videotaped, transcribed, and coded …

Combined X-Ray Diffraction And Diffuse Reflectance Analysis Of Nanocrystalline Mixed Sn(Ii) And Sn(Iv) Oxide Powders, Hongmei Deng, Jeanne Hossenlopp

Chemistry Faculty Research and Publications

Nanocrystalline mixtures of Sn(II) and Sn(IV) oxide powders, potential gas sensor materials, are synthesized via a simple precipitation route using SnCl(2) as the precursor. Materials are characterized by powder X-ray diffraction, thermogravimetric analysis, UV-visible diffuse reflectance spectroscopy (DRS), and Fourier transform infrared spectroscopy. The ratio of Sn(II)/Sn(IV) in powders precipitated at room temperature, as well as the identity of the primary Sn(II) product (SnO or Sn(6)O(4)(OH)(4)), can be varied by adjusting aging time and washing procedures. The identity of the initial Sn(II) product influences the subsequent phase composition and degree of disorder in the tetragonal SnO(2) phase obtained following sintering …

Atr-Ftir Spectroscopic Analysis Of Sorption Of Aqueous Analytes Into Polymer Coatings Used With Guided Sh-Saw Sensors, Yolanda K. Jones, Zhonghui Li, Michael M. Johnson, Fabien Josse, Jeanne Hossenlopp

Chemistry Faculty Research and Publications

Attenuated total internal reflectance Fourier transform infrared (ATR-FTIR) spectroscopy was used for the investigation of sorption of aqueous solutions of analytes into polymer coatings. A series of simple model polymers, such as poly(dimethylsiloxane), poly(epichlorhydrin), and poly(isobutylene), and films and analytes, such as aqueous solutions of ethylbenzene, xylenes, toluene, and nitrobenzene, were used to evaluate the use of ATR-FTIR spectroscopy as a screening tool for sensor development. The ratios of integrated infrared absorption bands provided a simple and efficient method for predicting trends in partition coefficients. Responses of polymer-coated guided shear horizontal surface acoustic wave (SH-SAW) sensor platforms to the series …

The Optimal Sulfonation Conditions Of Self-Doped Polyaniline Obtained By Using Experimental Strategies, Wen-Yar Li, Chi-Chang Hu

Journal of Electrochemistry

The optimal sulfonation condition of self-doped sulfonated polyaniline (prepared from leucoemeraldinebase; denoted as LEB-SPANI) with a high electronic conductivity was obtained by experimental strategies, includingthe fractional factorial design (FFD) and central composite design (CCD). From the FFD experiment, the self-doped LEB-SPANI prepared at a lowtemperature (4℃), a short reaction time (1 h), and a small volume of fumingsulfuric acid (10 mL) showed a better conductivity (ca.127 mS/cm). In the CCD study coupled with a confirmationtest, the highest conductivity (ca.141 mS/cm) of the LEB-SPANI film was obtained under a sulfonation temperatureof 4℃, a sulfonation time of 75 minutes, and a volume …

The High Temperature Corrosion Of 2205 Duplex Stainless Steel With Nacl Deposit, Fu-Fu Peng, Chaur-Jeng Wang, Yu-Chang Lin

Journal of Electrochemistry

The objective of this study was to figure out the hot corrosion behavior of 2205 duplex stainless steel (2205 DSS) within the temperature ranges from 550 to 850℃ in the static air condition with 2 mg/cm² NaCl deposit, and in the air atmosphere condition with a constant flow rate of 500 vppm NaCl_(g), respectively. Experimental results show that the hot corrosion kinetics met the parabolic rate law and the corrosion rate increased constantly with increasing temperature. The scales formed included Fe₂O₃/Fe₃O₄/Cr₂O₃ and FeCr₂O_{4 …}

A Study Of Three Corrosion Inhibitors For Reinforcing Steel In Sps Solution By Electrochemical Methods, Bing Zhao, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

Some electrochemical techniques such as linear polarization,electrochemical noise and EIS have been employedto study the inhibition behavior of N-lauroyl sarcosinate, β-sodium glycerophosphate and D-sodium gluconate for the reinforcing steel immersed in simulated concrete pore solution(SPS) with NaCl addition.The results show that D-sodium gluconatehas an obvious inhibitive effect for the reinforcing steelin containing Cl^- SPS solution. It has been proposed that the corrosion inhibition of D-sodium gluconate is due to its competitive adsorption and precipitation on steel surface in the simulated concrete environment.

Effect Of Hco3- Concentration On Co2 Corrosion In Gas And Oil Fields, Guo-An Zhang, Min-Xu Lu, Yin-Shun Wu

Journal of Electrochemistry

The effecs of HCO₃^- concentration on CO₂ corrosion in gas and oil fields were investigated by carrying out potentiodynamic scans and weight loss tests.Potentiodynamic polarization curves showed that the cathodic current density decreased with cm increase of HCO₃^- concentration when HCO₃^- was lower than 0.042(mol/L). The cathodic reations were promoted by increasing HCO₃^- when it reached 0.126 mol/L, Anodic behavior was an active process at low er [HCO₃^-] concentration and the anodic current density decreased with the increase of [HCO₃^-] concentration. An evident active-passive behavior …

An Investigation On Poly(Vinyl Chloride-Co-Isobutyl Vinyl Ether) Coatings Modified By Rutile Nano-Tio2 Pastes, Xiang Bin, Sheng-Tao Zhang, Yan Li, Bao-Rong Hou

Journal of Electrochemistry

The anti-corrosion coating of Poly(Vinyl Chloride-Co-Isobutyl Vinyl Ether) (PVCCIVE) was modified by rutile nano-TiO₂. The influence of nano-TiO₂ pastes on the coating's corrosion resistance was investigated through electrochemistry impedance spectroscopy (EIS). The results show that the addition of nano-TiO₂ pastes does not have obvious effect on the coating's performance of adhesion, flexility, impact resistance, but improves the coating's UV resistance and the gloss.Meanwhile,with the proper addition of rutile nano-TiO₂ pastes, the anti-corrosion behavior of the coating was advanced.

A Study Of Overcharge Characteristic Of Lithium-Ion Cells, Jing Pang, Shi-Gang Lu, Sha Liu

Journal of Electrochemistry

The overcharge characteristics and effect factors of lithium-ion cells containing LiMn₂O₄ cathodes were studied in detail. Overcharge testing of Lithium-ion cells with a systematic variation in the cell balance demonstrated that the overcharge characteristics of Lithium-ion cells was affected by the amount of cathode in the cells, which is independent of the amount of anode material. The rate of charge was found to be an important parameter, as electrolyte complete decomposition at low charge rates caused the end of overcharge testing, while high charge rates accelerated the rate of heat generation in the cells and the cell …

An Electrochemical Study Of Electroless Copper Plating Using Glyoxylic Acid As Reducing Agent, Li-Qiong Wu, Fang-Zu Yang, Ling Hang, Shi-Gang Sun, Shao-Min Zhou

Journal of Electrochemistry

The electroless copper plating using glyoxylic acid as a reducing agent,Na₂EDTA as a chelating agent and K₄FeCN₆ and 2,2'-dipyridyl as additives was studied. The effect of chelating agent and addtives on the polangation behaviovs of copper reduction and glyoxylie acid oxidation were analyzed by linear sweep voltammetry. The results mainly demonstrated that the chelating agent hindered both the oxidation of glyoxylic acid and the reduction of copper complexing ions. It has revealed that K₄FeCN₆ and 2,2'-dipyridyl (with the content over than 20 mg/L) both played negative actions on the oxidation of glyoxylic …

The Deactivation Mechanism Of Metal Oxide Anodes Under Alternative Current Electrolysis Condition, Jun-Tao Wang, Yan Han, Guang-Zhang Chen, Wen-Fa Liu

Journal of Electrochemistry

The metal oxide anodes coated on titanium used in seawater electrolysis were prepared by thermal decomposition. Their morphologies, compositions and phase structures were determined by scanning electron microscope(SEM), energy dispersive X-ray detector(EDX) and X-ray diffraction(XRD). The electrochemical properties of the anodes were characterized by accelerated life test, cyclic voltammetry and electrochemical impedance spectroscopy. SEM, EDX and XRD showed that solid solution structures of (Ru, Ir, Ti)O₂ and (Ir, Ti)O₂ were formed after pyrolysis, the solid solution structures and active components were disappeared after the deactivation of the anodes. Electrochemical results indicated that the active area decreased and the …

Copper Electrodeposition Under The Perturbation Of Hard Particles, Zeng-Wei Zhu, Di Zhu

Journal of Electrochemistry

Copper electrodepositon was carried out on the rotating cathode,with hard particles(such as ceramic beads) filling between the electrodes. The rotation of cathode led hard particles to polish and impact the surface of deposit during electrodeposition.Copper deposits with a mass of cuspidal nodules were produced in acid sulfate solutions while brittle deposits without nodules were produced in alkaline sulfate solutions. It was also found that brightening and smoothing deposit could be obtained from the alkaline solution, and the deposit was approximatively disordered orientation with granular morphology of about 100~300 nm. The results show that the polishing and impact of hard particles …

Silicides And Composites Materials As Anodes For Lithium Ion Batteries, Jun-Mei Yan, Hui-Zhen Huang, Jing Zhang, Yong Yang

Journal of Electrochemistry

The anode materials of Mg₂Si and MnSi were synthesized by mechanically activated annealing(MAA) techniques in this work and the in electrochemical performances were also studied.A series of composite materials of Mg₂Si and CNTs or CMS were prepared by ball-milling method respectively. The reversible capacities of the composites were higher than that of the pure Mg₂Si and pure carbon materials.The cyclic performances have been improved greatly by ball-milling of the Mg₂Si and carbon materials. Results show that ball-milling method is one kind of method to make alloy materials into practical use.