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Articles 5461 - 5490 of 6056

Full-Text Articles in Physical Sciences and Mathematics

Conversions From Cyclohexanol: An Undergraduate Laboratory Project, Samir B. Hanna, James T. Wrobleski, Joseph T. Bohanon, Billy W. Peace Jan 1971

Conversions From Cyclohexanol: An Undergraduate Laboratory Project, Samir B. Hanna, James T. Wrobleski, Joseph T. Bohanon, Billy W. Peace

Chemistry Faculty Research & Creative Works

No abstract provided.

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Magnetic Behavior Of Rare-Earth Iron-Rich Intermetallic Compounds, Dominique Givord, Remy Lemaire, William Joseph James, Jean Michel Moreau, Jayant S. Shah Jan 1971

Magnetic Behavior Of Rare-Earth Iron-Rich Intermetallic Compounds, Dominique Givord, Remy Lemaire, William Joseph James, Jean Michel Moreau, Jayant S. Shah

Chemistry Faculty Research & Creative Works

The thermal variation of lattice parameters of rare earth-transition metal intermetallic compounds rich in Fe, Co, or Ni in the temperature range of 25-900oK is studied. For the Fe compounds, negative thermal expansion is observed below their magnetic ordering temperatures regardless of the nature of substitutional ordering. For Co and Ni compounds, the thermal expansion behavior is normal. It is then concluded that for the Fe compounds, the magnetic properties are mainly determined by the Fe-Fe interatomic distances and the number of Fe nearest neighbors, whereas for Co and Ni compounds the magnetic properties are determined by the conduction electron …

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Synthesis, X-Ray Characterization, Structural And Magnetic Studies Of A New Class Of Iso-Structural Bimo₃ Compounds, Joseph Donato Bucci Jan 1971

Synthesis, X-Ray Characterization, Structural And Magnetic Studies Of A New Class Of Iso-Structural Bimo₃ Compounds, Joseph Donato Bucci

Doctoral Dissertations

"This dissertation consists of four sections. The first part is a temperature dependent X-ray study of the lattice parameters of BiFeo₃. The synthesis and subsequent X-ray characterization of BiCo₃, BiAlO₃, BiMnO₃ , BiScO₃, BiCo₁₋ₓFeₓO₃ , and BiAl₁₋ₓFeₓO₃ are reported in the second part. These compounds all crystallize in the body centered cubic (BCC) structure with a~10.2Å. Single crystal Precession and Weissenberg photographs confirmed the BCC structure. In part three, the results of the magnetic studies on BiCoO₃ and biAl.₉FE.₁ are presented. The magnetic data for BiCoO₃ are substantiated by X-ray thermal expansion studies. In the last part the compound BiCo.₉FE.₁O₃ …

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Some Metal Complexes Of Dihydroxycyclobutenedione, Stewart Michael Condren Jan 1971

Some Metal Complexes Of Dihydroxycyclobutenedione, Stewart Michael Condren

Doctoral Dissertations

"This study involves an investigation of some of the physical and chemical properties of the trivalent metal squarate complexes of iron, vanadium, and indium in order to determine their structure. In this investigation studies were made of the infrared spectra, electronic spectra, x-ray diffraction powder photographs and diffractometer patterns, magnetic susceptibilities, and thermogravimetric patterns for the trihydrate, dihydrate, and anhydrous squarate complexes of vanadium(III) and iron (III) and the dihydrate squarate complex of indium(III). These studies suggest that the structures of the vanadium(III) and iron(III) squarate complexes are dimeric with hydroxyl bridges between the metal atoms. This is supported by …

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Collision Cross Sections For The Excitation Of The Schumann-Runge Dissociation Continuum In Molecular Oxygen By 20-110-Kev Protons, John T. Park, F. D. Schowengerdt, D. R. Schoonover Jan 1971

Collision Cross Sections For The Excitation Of The Schumann-Runge Dissociation Continuum In Molecular Oxygen By 20-110-Kev Protons, John T. Park, F. D. Schowengerdt, D. R. Schoonover

Physics Faculty Research & Creative Works

Absolute cross sections for the excitation of the Schumann-Runge dissociation continuum of molecular oxygen have been obtained from inelastic energy-loss spectra induced by 20-110-keV protons incident on gaseous targets of molecular oxygen. Apparent differential energy loss cross sections, ionization cross sections, and total inelastic cross sections are also obtained from the energy-loss spectra. The proton energy-loss spectra have an energy resolution of about 2 eV. The energy location of the first peak in the energy-loss spectra of O2 is in general agreement with the findings of photo absorption and electron energy-loss-spectra measurements. The cross section for the Schumann-Runge dissociation continuum …

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Distribution, Petrology, And Environment Of The St. Louis-Ste. Genevieve Transition Zone In Missouri, Donald Howerton Fielding Jan 1971

Distribution, Petrology, And Environment Of The St. Louis-Ste. Genevieve Transition Zone In Missouri, Donald Howerton Fielding

Masters Theses

"In eastern Missouri, southeastern Iowa, and western Illinois - a transition zone, a body of rock consisting of several lithosomes which has a geographic extent measured in scores to hundreds of miles and which lies between a single overlying formation and a single underlying formation and which has lithologic and/or paleontologic properties common to both the overlying and the underlying formations, was found to exist between the St. Louis and the Ste. Genevieve formations. This transition zone is called the St. Louis-Ste. Genevieve Transition Zone, and is shown to possibly be due to continuous deposition between these two times and …

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Inclusion Theorems For Boundary Value Problems For Delay Differential Equations, Leon M. Hall Jan 1971

Inclusion Theorems For Boundary Value Problems For Delay Differential Equations, Leon M. Hall

Masters Theses

"In this thesis existence and uniqueness of solutions to certain second and third order boundary value problems for delay differential equations is established. Sequences of upper and lower solutions similar to those used by Kovač and Savčenko are defined by means of an integral operator, and conditions are given under which these sequences converge monotonically from above and below to the unique solution of the problem. Some numerical examples for the second order case are presented. Existence and uniqueness is also proved for the case where the delay is a function of the solution as well as the independent variable"--Abstract, …

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Freshwater Losses To The Sea And Water Level Decline In Northwest Libya, Mohammed Ahmed Attiga Jan 1971

Freshwater Losses To The Sea And Water Level Decline In Northwest Libya, Mohammed Ahmed Attiga

Masters Theses

"The area studied in this investigation, located in Tripolitania, Libya, between 13º and 16º east longitude and 31º and 33º north latitude, covers about 42,000 square kilometers. It is divided topographically into two parts. They are the coastal zone to the north and the Jebel (plateau) zone to the south. Some wadis which rise in the Jebel drain northward across the area to the sea. The temperature in the area ranges from 5ºC to 19ºC in the winter and from 19ºC to 40ºC in the summer. Precipitation in the area ranges from 380 millimeters to less than 100 millimeters. The …

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A Kinetic Study Of The Reductive Abilities Of Four Polyaminocarboxylic Acids (Edta, Cdta, Dtpa And Nta) Towards Cerium(Iv) In Perchloric Acid Media, Salem Ahmed Attiga Jan 1971

A Kinetic Study Of The Reductive Abilities Of Four Polyaminocarboxylic Acids (Edta, Cdta, Dtpa And Nta) Towards Cerium(Iv) In Perchloric Acid Media, Salem Ahmed Attiga

Masters Theses

"The reduction of Ce(IV) in HC10₄ solutions by four polyaminocarboxylic acids, which are commonly used as chelating agents, has been studied by the stopped-flow technique. The rates of reduction first increase with increasing acidity, reach maxima which are characteristic of the chelating agent and the medium, then progressively decrease with increasing the acid concentration in the media. At their maximum reactivities, trans-1,2-diaminocyclohexane tetraacetic acid (CDTA) shows the highest reductive ability; this is followed by ethylenedinitrilotetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and finally nitrilotriacetic acid (NTA). The observed maxima can be qualitatively explained in terms of a mechanism which involves unhydrolyzed …

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The Thermal Accommodation Coefficients Of Helium, Neon, And Argon On Surfaces, Gerald Lee Zweerink Jan 1971

The Thermal Accommodation Coefficients Of Helium, Neon, And Argon On Surfaces, Gerald Lee Zweerink

Doctoral Dissertations

"Measurements of the accommodation coefficients of helium, neon, and argon on an ice surface at 77ºK were accomplished; Measurements of the accommodation coefficients of helium and neon on a clean tungsten surface are also reported here; These data are compared with theoretical calculations of accommodation coefficients as well as with data from other experimental studies"--Abstract, pages iii-iv.

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The Vibrational Modes Of Spheroidal Cavities In Elastic Solids, David Stewart Jan 1971

The Vibrational Modes Of Spheroidal Cavities In Elastic Solids, David Stewart

Doctoral Dissertations

"A general analysis of all possible cavity shapes is given with a discussion of the mathematical difficulties involved for the various cases. Special emphasis is given to cavity shapes describable in terms of the coordinate surfaces of coordinate systems separating the scalar wave equation. 112 such shapes are identified and discussed. Free boundary condition equations for spheres and spheroids are derived in complete generality in terms of potentials. The difference in the vibrations of a solid and those of a cavity of the same shape is discussed and made clear. The impossibility of deriving a frequency equation for uniform radial …

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X-Ray And Mössbauer Spectroscopy Studies Of The Silicon-Antimony And Bismuth-Antimony Alloys, James Ralph Teague Jan 1971

X-Ray And Mössbauer Spectroscopy Studies Of The Silicon-Antimony And Bismuth-Antimony Alloys, James Ralph Teague

Doctoral Dissertations

"X-ray and Mossbauer spectroscopy were used to investigate two antimony alloys, Bi-Sb and Si-Sb, showing semiconductorsemimetallic transitions or vice versa, depending on the antimony concentration in the host lattice. Resistivity and density measurements were found to be helpful in the analysis of the results. X-ray studies for dislocation-free antimony-doped silicon showed that the lattice constant of the alloy increased as the antimony concentration increased from 10¹⁸ to 10¹⁹ Sb atoms/cc. Rather good agreement was found between theoretical and experimental changes in lattice constant for dislocation-free silicon. Mössbauer studies showed that the isomer shift decreased linearly with increasing antimony concentration, which …

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Second- And Third-Order Elastic Constants Of Aluminum And Lead, Tetsuro Suzuki Jan 1971

Second- And Third-Order Elastic Constants Of Aluminum And Lead, Tetsuro Suzuki

Physics Faculty Research & Creative Works

The second- and third-order elastic constants of Al and Pb are calculated as the second and third derivatives of the binding energy with respect to the finite deformation parameter. The binding energy is derived from a local pseudopotential by use of second-order perturbation theory. It is shown that the binding energy satisfied not only the diagonal equilibrium condition, but also the off-diagonal equilibrium condition, i.e., the first derivative of the binding energy with respect to a volume change as well as with respect to shear deformations is zero. Accordingly, the present method of calculation is based on a stable lattice …

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Magnetostriction And Magnetic Breakdown In Cadmium, J. M. Carter, Don M. Sparlin Jan 1971

Magnetostriction And Magnetic Breakdown In Cadmium, J. M. Carter, Don M. Sparlin

Physics Faculty Research & Creative Works

Studies of the monotonic magnetostriction of cadmium at 4.2 °K in applied magnetic fields to 70 kG have shown that the angular variation of an extremal point Hm is proportional to secθ. The magnitude of Hm is in close agreement with the onset of a breakdown orbit γ13 observed for the applied field within 35 °of the c axis. The range of observation of Hm coincides with the range of the orbit γ. © 1971 The American Physical Society.

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Electron-Impact Excitation Of Auto-Ionizing Levels In Cesium, Yu Bong Hahn, Kaare J. Nygaard Jan 1971

Electron-Impact Excitation Of Auto-Ionizing Levels In Cesium, Yu Bong Hahn, Kaare J. Nygaard

Physics Faculty Research & Creative Works

Auto-ionizing states in Cs between 12 and 20 eV have been studied by electron impact. The retarding-potential-difference method was used to obtain an electron beam with energy spread of about 0.1 eV. To determine the threshold energies, inelastically scattered electrons were analyzed by the trapped-electron method. We have been able to identify about 20 levels, and the agreement with spectroscopic data is excellent. A peak appearing at 12.80 eV is probably due to the quartet states observed by Feldman and Novick. © 1971 The American Physical Society.

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Absolute Excitation Cross Sections Of He+ In 20-100-Kev He+-He Collisions Using Energy-Loss Spectrometry, D. R. Schoonover, John T. Park Jan 1971

Absolute Excitation Cross Sections Of He+ In 20-100-Kev He+-He Collisions Using Energy-Loss Spectrometry, D. R. Schoonover, John T. Park

Physics Faculty Research & Creative Works

Application of positive-ion energy-loss spectrometry has been extended to include experimental determination of absolute excitation cross sections of ground-state helium ions. Helium ion-atom collisions were studied for impact energies ranging between 20-100 keV, in 10-keV intervals. The data were taken with an apparatus resolution between 0.6-0.8 eV full width at half-maximum (FWHM). Cross sections for transitions from ground state to the second and third principal quantum levels of the ion plotted as a function of impact energy were still rapidly increasing at 100 keV. The cross sections at this energy were (1.64 ± 0.28) x 10-18 cm2 for He+(1s122)→He+ (n=2) …

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Characterizing Topologies By Classes Of Functions And Multifunctions, Alexander Hamlin Cramer Jan 1971

Characterizing Topologies By Classes Of Functions And Multifunctions, Alexander Hamlin Cramer

Doctoral Dissertations

"Topological spaces are characterized by the algebraic and topological structures of their classes of continuous selfmaps. The problem of determining the topology of a set given certain classes of multifunctions or relations is considered. The algebraic structure of the upper semicontinuous multifunctions is shown to determine the topology of T₁ spaces. A partial order for classes of topologies for the real numbers is defined and relationships between various classes are established"--Abstract, page ii.

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Photoionization Of Photoexcited Cesium, Robert E. Hebner Jan 1971

Photoionization Of Photoexcited Cesium, Robert E. Hebner

Doctoral Dissertations

"A new method for obtaining the cross section for photoionization of photoexcited cesium is presented. The salient feature of this experiment is to use three crossed beams, i.e., two light beams intersecting a beam of cesium atoms. The cross section is determined by counting the ions produced by the two step process: Cs (6S) + h[upsilon]₁ --> Cs (6P) ; Cs (6P) + [upsilon]₂ --> Cs⁺ + e⁻ The relative cross section for the second step has been obtained from threshold (5060 Å) to 2500 Å. The excitation light source used in obtaining this cross section was a rf resonance …

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Modeling The Visual Pathway For Interactive Diagnosis Of Visual Fields, Chiam Geoffrey Goldbogen Jan 1971

Modeling The Visual Pathway For Interactive Diagnosis Of Visual Fields, Chiam Geoffrey Goldbogen

Doctoral Dissertations

"Visual fields are an important tool for the ophthalmologist in the detection, diagnosis, and monitoring of certain diseases and maladies of the visual pathway. The aim of the present research is to build a computer system which utilizes a learning machine to develop a mathematical model of the visual pathway. It is hoped that this system may be used in the field of ophthalmology as a teaching aid, or may assist in various aspects of diagnosis. Faults corresponding to blind or impaired areas of visual fields are extracted from medical records of a patient's condition. The structure of the model …

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Special Subrings Of Real, Continuous Functions, Paul Marlin Harms Jan 1971

Special Subrings Of Real, Continuous Functions, Paul Marlin Harms

Doctoral Dissertations

"Some lattice-ordered subrings of C(X) containing C*(X) are examined where X is a completely regular space. Each realcompact spaceY between [v]x and ßx is associated with a lattice-ordered subring of C(X) which is isomorphic to C(Y) and contains C*(X). The cardinal number of (ßX - [v]X) is a lower bound for the cardinal number of these subrings. Every prime ideal in each of these subrings is comparable with the intersection of the subring and a maximal ideal in C(X). The structure space of maximal ideals is studied for special subrings in C(X) containing CK(X), the continuous functions of …

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Trace Base Metals, Petrography, Rock Alteration Of The Productive Tres Hermanas Stock, Luna County, New Mexico, Peethambaram Doraibabu Jan 1971

Trace Base Metals, Petrography, Rock Alteration Of The Productive Tres Hermanas Stock, Luna County, New Mexico, Peethambaram Doraibabu

Doctoral Dissertations

"Zinc, lead and minor copper-bearing manto-type and vein- type deposits occur in Paleozoic sedimentary rocks adjoining the Tres Hermanas quartz monzonite stock, Luna County, New Mexico. In an attempt to prove or disprove a possible genetic relationship between these mineral deposits and the stock, 99 half-mile or closer orthogonal grid samples from the stock and 22 soil samples from a connecting alluvial area to the north were analysed by atomic absorption technique for trace contents of zinc, lead and copper. Thirty-two of the rock samples were selected on a wider grid and petrographically studied and modal analyses calculated. Argillic, sericitic …

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The Effects Of Divalent Metal Ions On The Micellar Properties Of Sodium Dodecyl Sulfate, Michael U. Oko, Raymond L. Venable Jan 1971

The Effects Of Divalent Metal Ions On The Micellar Properties Of Sodium Dodecyl Sulfate, Michael U. Oko, Raymond L. Venable

Chemistry Faculty Research & Creative Works

Critical micelle concentrations and micellar molecular weights have been determined for sodium dodecyl sulfate in the presence of nitrates of copper, lead, zinc, and magnesium and critical micelle concentrations have been determined with sodium nitrate and silver nitrate as the added electrolytes. The thickness of the ionic atmosphere at the critical micelle concentration has been found to be 34.1 Å with no electrolyte present and 33.6 Å with 9.66 x 10-6 M sodium or silver nitrate and was found to increase upon addition of the 2:1 electrolytes. This is explained in terms of molecular and ionic interactions. Micellar molecular weights …

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Metal Salt Catalyzed Carbenoids, Billy W. Peace Jan 1971

Metal Salt Catalyzed Carbenoids, Billy W. Peace

Doctoral Dissertations

"The interaction of diazomalonic esters with olefins in the presence of homogeneous copper(I) and copper(II) catalyst has been examined as a function of olefin structure, solvent media, ionic strength, catalyst structure and catalyst concentration, using partial rate data. It has been possible to determine the fine mechanistic details of the cycloproponation, C-H insertion and "dimer" forming reactions. The initial step is displacement of a ligand from copper by diazo compound in a pre-equilibrium, loss of nitrogen in the rate determining step, return of the ligand, displacement of metal from the carbenoid by olefin, followed by collapse to products. Studies revealed …

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Surface Plasmons And The Reflectivity Of N-Type Insb, William E. Anderson, Ralph William Alexander, Robert John Bell Jan 1971

Surface Plasmons And The Reflectivity Of N-Type Insb, William E. Anderson, Ralph William Alexander, Robert John Bell

Physics Faculty Research & Creative Works

The Reflectivity of N-Type InSb Has Been Measured in the Far Infrared. the Doping of the Samples Was Such that the Free-Carrier Plasma Frequency Was Near the LO Mode Frequency. the Results Suggest that Samples with a Sufficiently Thick Damage Layer Show Effects Due to Surface Plasmons. Use of a Simple Model Indicates that the Surface-Plasma Excitations Are Coupled to the Phonons. © 1971 the American Physical Society.

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Scattering Of Waves In Many Dimensions, I. Adawi Jan 1971

Scattering Of Waves In Many Dimensions, I. Adawi

Physics Faculty Research & Creative Works

Scattering by a spherical potential is discussed in all dimensions by one formulation using the partial-wave expansion method. The optical theorem relating the total scattering cross section σ to the forward scattering amplitude f(0) is derived.

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Experimental And Theoretical Study Of The Sign Preference In The Nucleation Of Water Vapor, Daniel R. White, James L. Kassner Jan 1971

Experimental And Theoretical Study Of The Sign Preference In The Nucleation Of Water Vapor, Daniel R. White, James L. Kassner

Physics Faculty Research & Creative Works

The nucleation of water vapor on ions in atmospheres of helium and argon was studied using an expansion type cloud chamber. Separation of the positive and negative ions was achieved so that the nucleation could be studied as a function of both the sign of the ionic charge and the supersaturation. A semiphenominological theory was developed as an extension of the classical liquid drop theory to include the effects of the ionic charge on the nucleation process. The theoretical model of the prenucleation embryo was assumed to possess an oriented dipole surface layer with the direction of orientation dependent on …

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Heisenberg Ferromagnet With Biquadratic Exchange, Harry A. Brown Jan 1971

Heisenberg Ferromagnet With Biquadratic Exchange, Harry A. Brown

Physics Faculty Research & Creative Works

The usual Heisenberg Hamiltonian with bilinear exchange -2JS→1•S→2 has been extended to include a biquadratic term -2αJ(S→1•S→2)2, with an adjustable parameter α. A method equivalent to constant coupling was employed to calculate the effect of the biquadratic exchange term on the Curie temperature, magnetization, susceptibility, specific heat, and entropy for lattices with spin-1 atoms. As α goes from 0 to 1, the Curie temperature falls by a factor 2 to 3, while the asymptotic Curie temperature is reduced by the factor 2. The magnetization rises much more rapidly below TC, and the specific heat has a peak and discontinuity several …

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Mössbauer Studies Of Bifeo₃-Pbtio₃ Perovskite-Type Solid Solutions, C. M. Yagnik, Robert Gerson, William Joseph James Jan 1971

Mössbauer Studies Of Bifeo₃-Pbtio₃ Perovskite-Type Solid Solutions, C. M. Yagnik, Robert Gerson, William Joseph James

Physics Faculty Research & Creative Works

The Mössbauer spectra of the ferroelectric solid solutions (BiFeO3)x(PbTiO)1-x have been studied as a function of temperature, mainly between room temperature and 600°C, using 57Fe in the solutions as an absorber. The quadrupole splitting increased and the isomer shift decreased between x = 0.05 and x = 0.70, a range in which the solutions are tetragonal and paramagnetic, and in which the unit cell volume increases with increasing x. The isomer shift, in particular, was primarily determined by the unit cell volume. Data are presented on the internal magnetic field of the antiferromagnetic …

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Sediment Properties And Depositional Environment Of The Minnelusa Formation (Permo-Pennsylvanian), Northern Black Hills, South Dakota And Wyoming, El-Magtuf Taleb Taleb Jan 1971

Sediment Properties And Depositional Environment Of The Minnelusa Formation (Permo-Pennsylvanian), Northern Black Hills, South Dakota And Wyoming, El-Magtuf Taleb Taleb

Masters Theses

"Permo-Pennsylvanian sedimentary rocks of the Minnelusa Formation of the Black Hills uplift, South Dakota and Wyoming, can be divided into upper, middle and lower divisions on the basis of lithology. The upper portion of 150 to 200 feet consists of gray and yellow sandstone, with some carbonates and shales in some sections. The middle portion, about 200 to 220 feet thick consists of gray and red sandstone with carbonate members including the prominent dolomite member at the base; some of the carbonates are cherty. The lower portion, 20 to 60 feet thick, consists of pink sandstone, arenaceous dolomite and thin …

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A Measurement Of The Capture Coefficient And Of The Vapor Pressure Of Co₂ From 69ºk To 80ºk, Michel Louis Chouarain Jan 1971

A Measurement Of The Capture Coefficient And Of The Vapor Pressure Of Co₂ From 69ºk To 80ºk, Michel Louis Chouarain

Masters Theses

"The capture coefficient of CO₂ gas at 135ºK on a surface of CO₂ at temperatures between 69ºK and 80ºK is measured by means of quartz crystal microbalances. The vapor pressure of CO₂ is measured in the same range of temperature"--Abstract, page ii.

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