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Full-Text Articles in Physical Chemistry
Bond Length And Bond Valence For Tungsten-Oxygen And Tungsten-Sulfur Bonds, F. D. Hardcastle, R. Lykins
Bond Length And Bond Valence For Tungsten-Oxygen And Tungsten-Sulfur Bonds, F. D. Hardcastle, R. Lykins
Journal of the Arkansas Academy of Science
In 1947, Linus Pauling presented an “empirical” dependence of bond valence (s, also referred to as bond order) and bond length R: s = exp[(R0-R)/b], where R0 is bond length of unit valence and “b” is a fitting parameter. Recently, an expression was derived for relating the b fitting parameter to theoretically derived atomic orbital exponents. With a method to calculate b, both R0 and atomic orbital exponents can be experimentally determined through optimized fitting for W-O and W-S bonds. In the present study, bond …
Bond Length And Bond Valence Relationships For Chromium Oxides, Chromium Sulfides, Molybdenum Oxides, And Molybdenum Sulfides, J. Labrecque, F. D. Hardcastle
Bond Length And Bond Valence Relationships For Chromium Oxides, Chromium Sulfides, Molybdenum Oxides, And Molybdenum Sulfides, J. Labrecque, F. D. Hardcastle
Journal of the Arkansas Academy of Science
Pauling determined an empirical logarithmic dependence of bond order (bond valence), s, to bond length, R, s = exp(R0 – R/ b), where R0 is unit bond length and b is a fitting parameter. Recently, an expression was derived for relating the b fitting parameter to theoretically derived atomic orbital exponents. With a method to calculate b, both R0 and atomic orbital exponents can be experimentally determined through optimized fitting for Cr-O, Cr-S, Mo-O, and Mo-S. In the present study, bond length – valence relationships are found for Cr-O, Cr-S, Mo-O, and Mo-S chemical …
A Bond Length – Bond Valence Relationship For Carbon – Nitrogen Bonds, C. Harris, F. D. Hardcastle
A Bond Length – Bond Valence Relationship For Carbon – Nitrogen Bonds, C. Harris, F. D. Hardcastle
Journal of the Arkansas Academy of Science
In a recent study, Pauling’s relationship between bond length and valence was derived along with a definition for his fitting parameter b that incorporates the orbital exponents for each atom contributing to the bond of interest. The values of b for various bonds, including C-N bonds, were calculated using the orbital exponent data. In this study, Pauling’s correlation between bond length and bond valence, as well as his valence sum rule, were used with the recently-derived definition for b in order to produce a relationship specifically applicable to C-N bonds. The resulting equation was checked against published x-ray diffraction data …
A General Valence-Length Correlation For Determining Bond Orders: Application To Carbon-Carbon And Carbon-Hydrogen Chemical Bonds, F. D. Hardcastle
A General Valence-Length Correlation For Determining Bond Orders: Application To Carbon-Carbon And Carbon-Hydrogen Chemical Bonds, F. D. Hardcastle
Journal of the Arkansas Academy of Science
A quantum-mechanical LCAO approach was used to derive Pauling’s popular empirical bond valencelength relationship s = exp((R₀-R)/b), where s is the bond order or bond valence associated with bond length R, and R₀ and b are fitting parameters. An expression for the b “empirical” fitting parameter is derived in terms of atomic orbital exponents. The b parameters calculated from the atomic orbital exponents are consistent with optimized b parameters. In general, atomic orbital exponents may be used to determine bond valence-length relationships for any chemical bond regardless of valence state, oxidation number, physical or chemical environment. In this study, almost …
Molecular Structure Of Fac-Aquadichlorotris(Dimethylsulfoxide)Ruthenium(Ii), L. Foster, J. Hardin, Mark Draganjac, B. C. Noll
Molecular Structure Of Fac-Aquadichlorotris(Dimethylsulfoxide)Ruthenium(Ii), L. Foster, J. Hardin, Mark Draganjac, B. C. Noll
Journal of the Arkansas Academy of Science
No abstract provided.
Microwave Synthesis Of Cis-Dichlorotetrakis(Dimethylsulfoxide)Ruthenium(Ii), A. Harvey, Mark Draganjac, S. Chui, R. Snell, E. Benjamin
Microwave Synthesis Of Cis-Dichlorotetrakis(Dimethylsulfoxide)Ruthenium(Ii), A. Harvey, Mark Draganjac, S. Chui, R. Snell, E. Benjamin
Journal of the Arkansas Academy of Science
No abstract provided.
Microwave Syntheses And Thermal Gravimetric Analysis Of Trans-Hydrogen Bis(Dimethylsulfoxide)Tetrachlororuthenate(Iii), S. Chui, Mark Draganjac, E. Benjamin, B. Rougaeu
Microwave Syntheses And Thermal Gravimetric Analysis Of Trans-Hydrogen Bis(Dimethylsulfoxide)Tetrachlororuthenate(Iii), S. Chui, Mark Draganjac, E. Benjamin, B. Rougaeu
Journal of the Arkansas Academy of Science
No abstract provided.
Density Functional Studies Of The Structure And Bonding Of Nitrosyl Metalloporphyrin Complexes, John P. Graham, Robbie Davis
Density Functional Studies Of The Structure And Bonding Of Nitrosyl Metalloporphyrin Complexes, John P. Graham, Robbie Davis
Journal of the Arkansas Academy of Science
Density functional calculations were used to determine optimized geometries fornitrosyl-metalloporphyrin complexes of Fe(II),Co(II)and Mn(II).The optimized structures were found to be consistent with experimental data and previous computational predictions using single point density functional calculations. Vibrational frequencies for the N-0stretching mode were also calculated and shown to be consistent with experimental data. The nature of the bonding between the metal center and nitrosyl ligand is discussed in relation to the structure of the M-N-0 linkage. The results were found to be consistent with previous descriptions derived from the Fenske-Hall approximate molecular orbital method. Other interesting structural features in the optimized geometries …
Perkin Reaction: Rapid And Efficient Process Optimization Through A Microwave/Design Of Experiments Couple, R. David Pace, Laura Mcwilliams
Perkin Reaction: Rapid And Efficient Process Optimization Through A Microwave/Design Of Experiments Couple, R. David Pace, Laura Mcwilliams
Journal of the Arkansas Academy of Science
Microwave chemistry and a Design of Experiments (DOE) protocol were employed together in order to rapidly and efficiently optimize a modified Perkin reaction. Microwave heating significantly reduced the reaction time, and the DOE provided a statistically significant understanding of underlying process relationships in a minimum number of experimental runs. In all, the reaction time was reduced from1hour to 2 minutes, factors important to yield were identified, an interesting cross-term interaction was discovered, and it was demonstrated that the more economical sodium acetate trihydrate catalyst was a viable alternative to the more costly anhydrous sodium acetate.
Electron Shock Waves, Mostafa Hemmati, Michael Weller, Taylor Duncan
Electron Shock Waves, Mostafa Hemmati, Michael Weller, Taylor Duncan
Journal of the Arkansas Academy of Science
In this paper we describe numerical investigations of breakdown waves concentrating on antiforce waves. We employed one-dimensional electron fluid dynamical equations for a luminous pulse wave propagating into a neutral gas region and subjected to an applied electric field. We assumed that the electrons were the main element in the propagation of the wave and that the electron gas partial pressure provided the driving force. These waves are considered to be shock fronted and are composed of two regions: the thin sheath region behind the shock front and the thicker quasi-neutral region following the sheath region. Our set of equations, …
Uranium-Uranium Collisions At Relativistic Energies, Bao-An Li, Matt Tilley
Uranium-Uranium Collisions At Relativistic Energies, Bao-An Li, Matt Tilley
Journal of the Arkansas Academy of Science
No abstract provided.
Study Of The Amplitude Of Pressure And Thrust Oscillations In A Lab-Scale Hybrid Rocket, Ann Wright, Lawrence Dunn, Brian Alford, Justin Patton, M. Keith Hudson
Study Of The Amplitude Of Pressure And Thrust Oscillations In A Lab-Scale Hybrid Rocket, Ann Wright, Lawrence Dunn, Brian Alford, Justin Patton, M. Keith Hudson
Journal of the Arkansas Academy of Science
Hybrid rockets are being studied as a potential replacement for the solid rocket boosters on the NASA space shuttle. One physical characteristic of hybrid rockets that must be understood and overcome is potentially severe pressure oscillations during combustion. Pressure oscillations inside the rocket combustion chamber lead to oscillations in the thrust of the rocket. These oscillations are damaging to potential human passengers and cargo and must be minimized. Current theories surmise that the oscillations are caused by combustion chamber geometry, oxygen feed line parameters, and/or fuel combustion characteristics. This study focuses on the role of the fuel characteristics in pressure …
Versatile Apparatus For Measuring Kinetics Of Gaseous Reactions By A Relative Method, Edmond W. Wilson Jr., Holly A. Sawyer, Amber A. Sawyer
Versatile Apparatus For Measuring Kinetics Of Gaseous Reactions By A Relative Method, Edmond W. Wilson Jr., Holly A. Sawyer, Amber A. Sawyer
Journal of the Arkansas Academy of Science
It is important that accurate, reproducible values for the rates of chemical reactions occurring in the atmosphere be obtained. The value of accurate kinetics measurements is to improve the accuracy of mathematical models used to forecast the state of the atmosphere. We describe a versatile, robust apparatus for obtaining atmospheric reaction rate values and their temperature dependencies by a relative method. This relative method has the advantage over absolute methods in that errors due to impurities and adsorption on walls of the reaction apparatus are minimized. In addition, relative values serve as an important verification for absolute values. The apparatus …
Analysis Of Phytoestrogens By High Performance Liquid Chromatography, Anne A. Grippo, Yan Xie, Benjamin L. Rougeau, William V. Wyatt
Analysis Of Phytoestrogens By High Performance Liquid Chromatography, Anne A. Grippo, Yan Xie, Benjamin L. Rougeau, William V. Wyatt
Journal of the Arkansas Academy of Science
Phytoestrogens are biochemicals synthesized in plants which mimic steroidal estrogen activity in mammals. Analysis of these compounds in the legumes which produce them and in body fluids is important to the study of their physiological effects. High pressure liquid chromatography (HPLC) has been found to be an efficient and sensitive method of identification and quantitation of isoflavonoids, one class of phytoestrogen. Here we report the separation of three isoflavonoids, biochanin A, genistein and daidzein using an HPLC system with a Cg reverse phase column and a linear gradient mobile phase containing acetonitrile and acetic acid/water (10/90, v/v) over 60 minutes. …
Synthesis And Molecular Structure Of [Cpru(Pph3)(Pms)2]Otf1.3/4 C2>H4C12, Paul M. Nave, Mark Draganjac, A. W. Cordes, Tosha M. Barclay
Synthesis And Molecular Structure Of [Cpru(Pph3)(Pms)2]Otf1.3/4 C2>H4C12, Paul M. Nave, Mark Draganjac, A. W. Cordes, Tosha M. Barclay
Journal of the Arkansas Academy of Science
No abstract provided.
Electron Shock Waves: Effect Of Current On Electron Temperature And Density, Mostafa Hemmati, Mathues Shane Doss
Electron Shock Waves: Effect Of Current On Electron Temperature And Density, Mostafa Hemmati, Mathues Shane Doss
Journal of the Arkansas Academy of Science
In our attempt to find analytical solutions for breakdown waves, we employ a set of three-component fluid equations. In addition to reporting the method of integration of electron fluid dynamical equations through the dynamical transition region (sheath region), the wave profile for ionization rate, electron number density and electron temperature inside the sheath will be discussed. Also, the effect of the current on electron temperature, electron number density and ionization rate will be reported.
Preparation Of Powder Precursors And Evaporation Of Photoconductive Indium Sulfide Films, Chris Barber, Robert Engelken, Brandon Kemp, Wasim Aleem, Imran Khan, Chris Edrington, Michael Buck, Clayton Workman, Anup Thapa, Tom Jakobs
Preparation Of Powder Precursors And Evaporation Of Photoconductive Indium Sulfide Films, Chris Barber, Robert Engelken, Brandon Kemp, Wasim Aleem, Imran Khan, Chris Edrington, Michael Buck, Clayton Workman, Anup Thapa, Tom Jakobs
Journal of the Arkansas Academy of Science
We have demonstrated significant photoconductance in indium sulfide thin films prepared by thermal vacuum evaporation ofIn2$3 powders synthesized in-house by chemical precipitation ofInCl3 or In(CH3COO)3, and (NH4)2S or Na2S. The Delta G lambda/Gdark values have been as high as 0.1 in the initial unoptimized films. Excess sulfur (via a mixture of polysulfide and sulfide ions in the synthesis bath) appears to be important in achieving reproducible and large photoconductivities. In2S3 is particularly attractive as a lower toxicity alternative to CdS in optoelectronic applications such as photovoltaic and photoconductive cells.
Effective, Reliable, Inexpensive Cryofixation Device, Lawrence A. Mink, Roger A. Buchanan
Effective, Reliable, Inexpensive Cryofixation Device, Lawrence A. Mink, Roger A. Buchanan
Journal of the Arkansas Academy of Science
No abstract provided.
Electrochemistry Of Dihalogenated Nicotonic Acids In Aqueous And Aprotic Media, Ali U. Shaikh, Tappi A. Dixon, Lourie A. Battles, Frank L. Setliff
Electrochemistry Of Dihalogenated Nicotonic Acids In Aqueous And Aprotic Media, Ali U. Shaikh, Tappi A. Dixon, Lourie A. Battles, Frank L. Setliff
Journal of the Arkansas Academy of Science
The electrochemical reduction of several 2,5- and 5,6- dihalonicotinic acids have been studied in dimethyl sulfoxide as well as in aqueous buffers of different pH. The polarographic half-wave potentials for the reduction of these compounds in both media are reported here. The compounds appear to reduce at the carboxyl group. The presence of halogen atoms on the pyridine ring facilitates reduction.
Mathematics Of The Variation And Mole Ratio Methods Of Complex Determination, James O. Wear
Mathematics Of The Variation And Mole Ratio Methods Of Complex Determination, James O. Wear
Journal of the Arkansas Academy of Science
No abstract provided.