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Full-Text Articles in Physical Sciences and Mathematics
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 …
Wave Profile For Anti-Force Waves With Maximum Possible Currents, M. Hemmati, R. Horn, W. P. Childs, A. K. Meredith
Wave Profile For Anti-Force Waves With Maximum Possible Currents, M. Hemmati, R. Horn, W. P. Childs, A. K. Meredith
Journal of the Arkansas Academy of Science
In the theoretical investigation of the electrical breakdown of a gas, we apply a one-dimensional, steady state, constant velocity, three component fluid model and consider the electrons to be the main element in propagation of the wave. The electron gas temperature, and therefore the electron gas partial pressure, is considered to be large enough to provide the driving force. The wave is considered to have a shock front, followed by a thin dynamical transition region. Our set of electron fluid-dynamical equations consists of the equations of conservation of mass, momentum, and energy, plus the Poisson's equation. The set of equations …
Bond Length - Bond Valence Relationships For Carbon - Carbon And Carbon - Oxygen Bonds, C. Harris, F. D. Hardcastle
Bond Length - Bond Valence Relationships For Carbon - Carbon And Carbon - Oxygen Bonds, C. Harris, F. D. Hardcastle
Journal of the Arkansas Academy of Science
In the present study, relationships are developed for determining bond orders (also referred to as bond valences or bond numbers) from published bond lengths for carbon-carbon (C-C) and carbon-oxygen (C-O) bonds. The relationships are based on Pauling’s empirical formula s = exp((Ro-R)/b)), where s is the bond order, R is the corresponding bond length, Ro is the unit valence bond length, and b is a fitting parameter. We use a recently derived relationship for the b parameter in terms of the bonding atoms’ published atomic orbital exponents. The resulting equations were checked against published x-ray diffraction (XRD) data for 176 …
Low-Level Mercury Causes Inappropriate Activation In T And B Lymphocytes In The Absence Of Antigen Stimulation, K. L. Weigand, J. L. Reno, B. M. Rowley
Low-Level Mercury Causes Inappropriate Activation In T And B Lymphocytes In The Absence Of Antigen Stimulation, K. L. Weigand, J. L. Reno, B. M. Rowley
Journal of the Arkansas Academy of Science
The immune system primarily utilizes two cell types for adaptive immunity: T lymphocytes and B lymphocytes. T lymphocytes are activated when antigen presenting cells (APCs) present antigen to membrane-bound T cell receptors. B lymphocytes are activated when an antigen binds to receptors embedded in the plasma membrane. In both T and B cells this antigen binding crosslinks the receptor complexes and initiates the signal transduction cascade. These cascades frequently consist of a series of intracellular molecules becoming phosphorylated in a step-wise fashion. Once activated, these cells differentiate into effector cells that clear out the stimulating antigen. Mercury, which is a …
Low Speed Current Bearing Anti-Force Waves, M. Hemmati, W. P. Childs, H. Shojaei, H. Morris
Low Speed Current Bearing Anti-Force Waves, M. Hemmati, W. P. Childs, H. Shojaei, H. Morris
Journal of the Arkansas Academy of Science
For theoretical investigation of electrical breakdown of a gas, we apply a one-dimensional, steady profile, constant velocity, three-component (electrons, ions and neutral particles) fluid model. Our fluid model consists of the equations of conservation of mass, momentum and energy, coupled with the Poison’s equation. The set of equations is referred to as the electron fluid dynamical equations (EFD). This investigation involves breakdown waves with a substantial current behind the wave front, and waves for which the electric field force on electrons is in the opposite direction of the wave propagation (anti-force waves – lightning return stroke). Therefore, the set of …
Wave Profile For Current Bearing Antiforce Waves, H. Morris, W. Childs, P. Pinkston, M. Hemmati, J. Christensen
Wave Profile For Current Bearing Antiforce Waves, H. Morris, W. Childs, P. Pinkston, M. Hemmati, J. Christensen
Journal of the Arkansas Academy of Science
For fluid dynamical analysis of breakdown waves, we employ a one-dimensional, three-component (electrons, ions and neutral particles) fluid model to describe a steady-state, ionizing wave propagating counter to strong electric fields. The electron gas temperature and therefore the electron fluid pressure is assumed to be large enough to sustain the wave motion down the discharge tube. Such waves are referred to as antiforce waves. The complete set of equations describing such waves consists of the equations of conservation of mass, momentum and energy coupled with Poisson’s equation. Inclusion of current behind the wave front alters the set of electron fluid …
Microwave Assisted Synthesis Of Chloropentahaptocyclopentadienediphenylphosphinoethaneruthenium(Ii), S. Muthyala, Mark Draganjac
Microwave Assisted Synthesis Of Chloropentahaptocyclopentadienediphenylphosphinoethaneruthenium(Ii), S. Muthyala, Mark Draganjac
Journal of the Arkansas Academy of Science
No abstract provided.
Molecular Structure Of Pentahaptocyclopentadienebis (Tetrahydrothiophene) Triphenylphosphineruthenium(Ii) Triflate, Paul M. Nave, Mark Draganjac, A. W. Cordes
Molecular Structure Of Pentahaptocyclopentadienebis (Tetrahydrothiophene) Triphenylphosphineruthenium(Ii) Triflate, Paul M. Nave, Mark Draganjac, A. W. Cordes
Journal of the Arkansas Academy of Science
No abstract provided.
Synthesis, Characterization, And Properties Of Homometallic Dinuclear Ruthenium Complex Containing Chloro-Phenanthroline And Bipyridine, A. A. Bhuiyan, S. Kudo
Synthesis, Characterization, And Properties Of Homometallic Dinuclear Ruthenium Complex Containing Chloro-Phenanthroline And Bipyridine, A. A. Bhuiyan, S. Kudo
Journal of the Arkansas Academy of Science
This paper deals with the synthesis and spectroscopic investigation of homometallic dinuclear ruthenium(II) complex containing chlorophenanthroline and bipyridine ligands. This bimetallic ruthenium polypyridine complex may be useful for biological electron transfer studies. Heteroleptic ruthenium monomer complex Ru(bpy)2(Cl-phen) (where bpy = 2,2’-bipyridine and Cl-phen = 5-chloro- 1,10-phenanthroline) was prepared in a two step procedure previously developed in our laboratory. This monomer complex was used to prepare the ruthenium dimer complex, (bpy)2Ru(phen-phen)Ru(bpy)2, by utilizing the Ni-catalyzed coupling reaction. Both the complexes were purified by column chromatography. The identity and the integrity of the complexes were confirmed by elemental analysis as well as …
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 In Piano Stool Carbene Complexes, John P. Graham, Robbie Davis
Density Functional Studies Of The Structure And Bonding In Piano Stool Carbene Complexes, John P. Graham, Robbie Davis
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, …
Studies Of Zeolite Entrapped Ruthenium Polypyridine Complexes, Anwar A. Bhuiyan
Studies Of Zeolite Entrapped Ruthenium Polypyridine Complexes, Anwar A. Bhuiyan
Journal of the Arkansas Academy of Science
There is an intense interest in designing molecular systems which will absorb visible sunlight, initiate an electron transfer process, and ultimately convert the solar energy to useful chemical energy of fuels such as hydrogen produced from water. The zeolite-entrapped polypyridine complexes of divalent ruthenium hold promise as efficient photocatalysts for net charge separation and such efficiencies are further enhanced by organized incorporation of donor and acceptor components. This paper deals with the synthesis and spectroscopic investigation of zeolite-entrapped ruthenium polypyridine complexes which may be useful in the development of solar energy conversion schemes. The sensitizer molecules, such as Ru(bpy)3 2+ …
Fenske-Hall Approximate Molecular Orbital Analysis Of The Chelating Carbene Complex Eta5-Cp'(Co)Mn{C(Oet)Ch2pph2}, John P. Graham
Fenske-Hall Approximate Molecular Orbital Analysis Of The Chelating Carbene Complex Eta5-Cp'(Co)Mn{C(Oet)Ch2pph2}, John P. Graham
Journal of the Arkansas Academy of Science
The novel three legged piano stool chelating carbene complex, Cp'(CO)Mn{C(OEt)CH2PPh2}, 1, exhibits interesting structural, spectroscopic and electrochemical properties. It also readily undergoes reaction with CO to produce the three legged piano stool complex Cp'(CO)2{PPh2C(OEt)=CH2}, 2. This is in contrast to the analogous non-chelating complex Cp(CO)(PPh3)Mn{C(OMe)CH2CH3}, 3, which does not react with CO. This paper discusses the results of Fenske-Hall approximate molecular orbital calculations on model complexes for 1 and 3. The differences in spectroscopic and electrochemical properties are explained using molecular orbital analysis. Possible reasons for the enhanced reactivity of 1are also presented.
Stabilization Of Polyvinyl Chloride By Some Conducting Polymers, Amit Shah, Brian C. Berry, Ali U. Shaikh
Stabilization Of Polyvinyl Chloride By Some Conducting Polymers, Amit Shah, Brian C. Berry, Ali U. Shaikh
Journal of the Arkansas Academy of Science
No abstract provided.
Solid Phase Extraction Of Pesticides With Determination By Gas Chromatography, Anwar A. Bhuiyan, Harry O. Brotherton
Solid Phase Extraction Of Pesticides With Determination By Gas Chromatography, Anwar A. Bhuiyan, Harry O. Brotherton
Journal of the Arkansas Academy of Science
A simple, rapid, and effective method for the extraction of fifteen organochlorine and organophosphorus pesticides based on the use of solid phase Bond Elut C-18 cartridges was studied as an alternative method to those based on extraction with organic solvents. Solid phase extraction is an attractive chromatographic sample preparation technology that reduces analysis time, costs, labor, and solvent consumption relative to traditional liquid/liquid extraction methods. The sample recoveries with the use of solid phase extractions were excellent for most pesticides. Analyte concentration by a factor as great as 1000-fold was achieved readily. The adsorbed pesticides were eluted from the solid …
Reduction Of Dendrite Formations To Improve The Appearance Of The Powder Cured Films For Automotive Industry, Alexandru S. Biris, C. U. Yurteri, Malay K. Mazumder, Robert A. Sims, P. H. Williams
Reduction Of Dendrite Formations To Improve The Appearance Of The Powder Cured Films For Automotive Industry, Alexandru S. Biris, C. U. Yurteri, Malay K. Mazumder, Robert A. Sims, P. H. Williams
Journal of the Arkansas Academy of Science
The appearance of powder-coated films is dependent upon powder chemistry and spraying parameters. One of the most important physical factors controlling the powder film appearance is the microdeposition of the powder particles on the grounded substrate. During the electrostatic deposition of powder, the formation of dendrites and agglomerates was observed; these formations have an adverse effect on the final film appearance and their elimination may result in smoother and glossier films. Dendrites are generated due to bipolar charging and inter-particulate electrostatic attractive forces. The corona charging technique is mostly used in industrial powder coating applications. At low corona voltages (- …
Electrostatic Microencapsulation Of Composite Particulate Materials For Manufacturing And Environmental Applications, S. De, M. Pritchett, Malay K. Mazumder, Robert A. Sims, C. U. Yurteri, Alexandru S. Biris, A. Rego
Electrostatic Microencapsulation Of Composite Particulate Materials For Manufacturing And Environmental Applications, S. De, M. Pritchett, Malay K. Mazumder, Robert A. Sims, C. U. Yurteri, Alexandru S. Biris, A. Rego
Journal of the Arkansas Academy of Science
Electrostatic microencapsulation is a dry coating process where two powders, one containing the fines and the other relatively larger particles, are separately dispersed in air and pre-charged with opposite polarity, using corona charging for electrostatic coagulation. These oppositely charged core and guest particles experience attractive electrostatic forces and generate composite particles. Preliminary experiments of electrostatic microencapsulation were performed using Anionic Exchange Resin (AG 1-X8) as the host particle and Red Toner (Omega 4000) as the guest particles. An electrostatic microencapsulation tower has been designed for generation of composite particles using particles of different particle size distribution.
Chemical Composition Of Particles Of D < 0.20 Mu In The Lower Stratospheric Aerosol, Spring 1993, Joseph D. Scott, David M. Chittenden Ii
Chemical Composition Of Particles Of D < 0.20 Mu In The Lower Stratospheric Aerosol, Spring 1993, Joseph D. Scott, David M. Chittenden Ii
Journal of the Arkansas Academy of Science
The majority of the mass of stratospheric aerosol collected during the spring of 1993 consisted principally of particles of d >0.20 mu containing a mixture of H2SO4 and (NaK)2SO4. However, the composition of the more numerous particles with d< 0.2 mu was very different. X-ray emission spectra (EDS) of individual particles indicated that there were three different chemical populations of small particles. The most numerous population was almost all C with only traces of S and Na. The second population contained metal sulfates and chlorides, possibly accreted to a C-containing matrix. The third population consisted of S- and Cl- containing species and trace amounts of Na and K ions. The number of equivalents of metal ion was much less than that of S and Cl species, indicating that most of the S and Cl was not ionic, but was covalently bonded, perhaps to a C matrix.
Modification Of Surface Properties Of Polymeric Materials, Rajesh Sharma, Robert A. Sims, Malay K. Mazumder
Modification Of Surface Properties Of Polymeric Materials, Rajesh Sharma, Robert A. Sims, Malay K. Mazumder
Journal of the Arkansas Academy of Science
Polymeric materials are successfully used in virtually all industries ranging from semiconductors, and coatings, to household appliances, automotive, and biomedical implants. Polymers generally have excellent bulk physical and chemical properties. However, certain properties of polymers such as low surface energy, low wettability, and high electrical resistivity sometimes limit their applications. Changing the bulk formulation of the polymers can alter some of these properties, but in general this is not acceptable as it can affect "desirable" bulk properties. Surface modification techniques have been used to alter polymer surfaces without affecting the bulk properties of the material. Most polymers have very high …
Alumina And Synthesis Intermediates Derived From Diethylkaluminum Amide, Benzaldehyde And Water, Stephen E. Hall, Lize Wilcox, William S. Tyree, David A. Lindquist, Malay K. Mazumder
Alumina And Synthesis Intermediates Derived From Diethylkaluminum Amide, Benzaldehyde And Water, Stephen E. Hall, Lize Wilcox, William S. Tyree, David A. Lindquist, Malay K. Mazumder
Journal of the Arkansas Academy of Science
The reaction of diethylaluminum amide [Et2AINH2] with benzaldehyde in toluene produces a solution of ethylaluminoxane polymer [EtAlO] and hydrobenzamide [PhCH=NCH(Ph)N=CHPh]. Alumina then is precipitated by the addition of water. Transition aluminas that may be useful in heterogeneous catalyst applications are obtained after calcining. Details of the chemistry of solution intermediates according to 1H NMR and the properties of the alumina product according to surface area analyses and powder x-ray diffraction are described.
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.
Synthesis Of A Ruthenium-Tetra(Tht)Dichloride Compound And The Molecular Structure Of The Partially Oxidized Compound Rucl2(Tht)2.2(Tht-O)1.8, L. A. Thornton, Mark Draganjac, Andres Meza, A. W. Cordes
Synthesis Of A Ruthenium-Tetra(Tht)Dichloride Compound And The Molecular Structure Of The Partially Oxidized Compound Rucl2(Tht)2.2(Tht-O)1.8, L. A. Thornton, Mark Draganjac, Andres Meza, A. W. Cordes
Journal of the Arkansas Academy of Science
No abstract provided.