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UNT College of Arts and Sciences
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UNT Scholarly Works
- ₁¹H+ - and ₂⁴He+ - induced M-shell x-ray-production cross sections for selected elements in the rare-earth region
- This article discusses ₁¹H+ - and ₂⁴He+ -induced M-shell x-ray production cross sections for selected elements in the rare-earth region. Abstract: The measurements of M-shell x-ray-production cross sections induced by ₁¹H+ and ₂⁴He+ ions are compared to the first-Born-approximation and ECPSSR (energy loss, Coulomb-deflection effects; perturbed-stationary-state approximation, with relativistic corrections) theories. Most of the reported experimental data were measured in the authors' laboratory and the other measurements were taken from the literature. The data from the authors' laboratory were for incident H+ and He+ ions in the energy range from 0.25 to 2.5 MeV. The M-shell x-ray-production cross sections were measured for the following thin targets: 59Pr, 60Nd, 63Eu, 64Gd, 66Dy, 67Ho, 68Er, 70Yb, and 72Hf. The data were for the following elements: 54Xe, 59Pr, 60Nd, 62Sm, 63Eu, 64Gd, 65Tb, 66Dy, 67Ho, 68Er, 70Yb, 72Hf, 73Ta, 74W, 78Pt, 79Au, 80Hg, 82Pb, 83Bi, and 92U. The first-born-approximation calculations of the ionization cross section were made using the plane-wave Born approximation for direct ionization and the Oppenheimer-Brinkman-Kramers approximation of Nikolaev for electron capture. The ECPSSR theory of Brandt and Lapicki [Phys. Rev. A 23, 1717 (1981)] goes beyond the first Born approximation and accounts for the energy loss, Coulomb deflection, and relativistic effects in the perturbed-stationary-state theory. The first Born approximation overpredicts all measurements. The ECPSSR theory predicts the M-shell production cross sections correctly for Z2 > 70 and energies per μ > 0.25 MeV/μ. In the rare-earth region the ECPSSR results lie above the data at higher projectile energies and fall off below the data at lower energies. digital.library.unt.edu/ark:/67531/metadc139491/
- L- and M-shell x-ray production cross sections of Nd, Gd, Ho, Yb, Au, and Pb by 25-MeV carbon and 32-MeV oxygen ions
- This article discusses L- and M-shell x-ray production. Abstract: L- and M-shell x-ray production cross sections have been measured for thin solid targets of neodymium, gadolinium, holmium, ytterbium, gold and lead by 25-MeV ₆¹²C(q)+ (q=4,5,6) and by 32-MeV ₈¹⁶O(q)+ (q=5,7,8). The cross sections were determined from measurements made with thin targets (less than 2.25 μg/cm2). For projectiles with one or two K-shell vacancies, the target x-ray production cross sections were found to be enhanced over those for projectiles without a K-shell vacancy. The sum of direct ionization to the continuum (DI) plus electron capture (EC) to the L,M,N,... shells and EC to the K shell of the projectile have been extracted from the data. The results are compared to the predictions of first Born theories, i.e., plane-wave Born approximation for DI and Oppenheimer-Brinkman-Kramers formula of Nikolaev for EC, and to the ECPSSR that accounts for energy loss and Coulomb deflection of the projectile as well as for relativistic and perturbed stationary states of inner-shell electrons. digital.library.unt.edu/ark:/67531/metadc139494/
- Calculating Changes in Worklife Expectancies and Lost Earnings in Personal Injury Cases
- This article discusses calculating changes in worklife expectancies and lost earnings in personal injury cases. Abstract: This paper utilizes the Bureau of Labor Statistics (BLS) new worklife tables' information on workforce participation probabilities to estimate the effect of an injury on a worker's life expectancy, worklife expectancy and discounted expected income. After a medical opinion has been obtained concerning the effect of an injury on a worker's probabilities of living and remaining active, the BLS's probability figures can be adjusted and incorporated into a Markov process to estimate the impact of the injury. It is shown that Alter and Becker's technique can be adapted to estimate the present value of the lost expected income. digital.library.unt.edu/ark:/67531/metadc71789/
- Carbon K-shell x-ray and Auger-electron production in hydrocarbons and carbon oxides by 0.6-2.0-MeV protons
- This article discusses carbon K-shell x-ray and Auger-electron production in hydrocarbons and carbon oxides by 0.6-2.0-MeV protons. Abstract: Carbon K-shell x-ray and Auger-electron-production cross sections are reported for 0.6-2.0-MeV protons incident on CH4 (methane), C2H2 (acetylene), n-C4H10 (normal butane), i-C4H10 (isobutane), C6H6 (benzene), CO, and CO2. A variable-geometry end-window proportional counter with an alternative procedure for the determination of its transmission was used in collection of the x-ray data. A constant-energy-mode π/4 parallel-plate electrostatic analyzer served in the detection of Auger electrons. K-shell Auger-electron-production cross sections are compared with the predictions of the first Born theory and the perturbed-stationary-state theory which accounts for energy-loss, Coulomb deflection, and relativistic effects (ECPSSR). These data show fair agreement with the ECPSSR theory when the chemical shifts, of the carbon K-shell binding energy in molecules, are included in the calculations. This agreement is even better after effects of intramolecular scattering are considered. Validity of the geometrical model by Matthews and Hopkins [Phys. Rev. Lett. 40, 1326(1978)] is established after a scrutiny of the inelastic cross sections for scattering of Auger-electrons within the molecule and their effective dislocation out of the detector's window. The x-ray cross sections show particularly strong variations with the target molecular species because of additional changes due to modifications in the fluorescence yields for molecular carbon. The correlation of these changes with the molecular character of carbon and a scaling procedure for the fluorescence yields in molecules will be discussed elsewhere. digital.library.unt.edu/ark:/67531/metadc139493/
- Comment on the Prediction of Gas Chromatographic Retention Behavior with Mixed Liquid Phases
- This article comments on the prediction of gas chromatographic retention behavior with mixed liquid phases. digital.library.unt.edu/ark:/67531/metadc146582/
- O demonstratie directă a faptului că L1 (X, B, μ) verifică principiul tare al maximului modulului
- This paper proposes a new direct proof of the fact that L^1 verifies the strong maximum principle, i.e., any analytic map from the complex unit disk into L^1, constant in norm, must be constant. digital.library.unt.edu/ark:/67531/metadc152439/
- Direct ionization and electron capture in M-shell x-ray production by fluorine ions
- This article discusses direct ionization and electron capture in M-shell x-ray production by fluorine ions. Abstract: Measurements of M-shell x-ray production cross sections are reported for thin solid targets of 79Au, 82Pb, 83Bi, and 92U. Fluorine ions of energies 25, 27, and 35 MeV and charge states of 4,5,6,8, and 9 were used. The microscopic cross sections were determined from measurements made with targets ranging in thickness from ~1 to ~300 μg/cm2. An enhancement in the target M-shell x-ray production cross section was observed for fluorine ions with one or two K-shell vacancies over those without a K-shell vacancy. The sums of cross sections for direct ionization to the target continuum and electron capture to the projectile's L,M,N,... shells are inferred from charge state q=4,5,6 data. The first Born calculations overpredict the cross-section data at all energies. Cross sections for electron capture from the target M shell to the projectile K shell for one (q = 8) and two (q = 9) K-shell vacancies in the projectile are also overpredicted by the first Born approximation for electron capture, i.e., the Oppenheimer-Brinkman-Kramers approximation of Nikolaev. The data are in good agreement with the ECPSSR theory of Brandt and Lapicki, which accounts for the energy-loss, Coulomb-deflection, and relativistic effects in the perturbed-stationary-state theory. digital.library.unt.edu/ark:/67531/metadc139488/
- Electron capture from K shells by fully stripped ions
- This article discusses electron capture from K shells by fully stripped ions. Abstract: Cross sections for electron capture from inner shells by fully stripped ions are calculated and compared with data for K-shell vacancy production. A procedure for inclusion of the relativistic effect is developed, and the scheme of calculations is illustrated through sample evaluations of electron-capture cross sections. digital.library.unt.edu/ark:/67531/metadc139484/
- Excess Molar Volumes of Binary Mixtures of Cyclohexane and y-Butyrolactone with Aromatic Hydrocarbons
- This article discusses excess molar volumes of binary mixtures of cyclohexane and y-butyrolactone with aromatic hydrocarbons. Abstract: Excess molar volumes of cyclohexane + benzene, cyclohexane + toluene, cyclohexane + p-xylene, y-butyrolactone + benzene, y-butyrolactone + toluene, and y-butyrolactone + m-xylene have been measured at 298.15 K. For the first three systems, Vᴱ is positive throughout the entire concentration range. Vᴱ is negative for binary mixtures containing y-butyrolactone, which indicates significant interaction between y-butyrolactone and the aromatic hydrocarbon. digital.library.unt.edu/ark:/67531/metadc152457/
- Experimental Artifacts and Determination of Accurate Py Values
- This article discusses experimental artifacts and determination of accurate Py values. Abstract: Recently the Py solvent scale has been introduced and a large body of data has been generated using fluorescence measurements. Numerous problems exist in the correct determination of these values, including instrumental and chemical artifacts. Among the instrumental problems associated with correct Py assignments are slit width effects, inner filtering and efficiencies associated with double-pass vs. single-pass cell compartment designs. These instrumental problems, together with chemical artifacts related to adequate blank correction and temperature control, were investigated in the work reported in this paper. digital.library.unt.edu/ark:/67531/metadc152446/
- Fast diffusion of As in polycrystalline silicon during rapid thermal annealing
- This article discusses fast diffusion of As in polycrystalline silicon during rapid thermal annealing. Abstract: The diffusion of As in polycrystalline silicon films subjected to rapid thermal annealing has been studied using sheet resistance and Rutherford backscattering. The polycrystalline Si films were deposited on oxidized silicon wafers, implanted with As, and annealed with a Varian IA-200 isothermal annealer. Infrared radiation from a resistively heated sheet of graphite heats the wafer, in a vacuum, to temperatures > 1000 °C for times on the order of a few seconds. The rate of diffusion and rate of loss of As from the polycrystalline Si is much faster than the diffusion rate and loss rate in single crystal Si annealed with identical conditions. Diffusion prior to grain growth agrees with previously reported results for As in polycrystalline Si. However, grain growth appears to enhance As diffusion. digital.library.unt.edu/ark:/67531/metadc146574/
- Generalizarea problemei 0:59
- This note extends a certain combinatorics problem of I. Tomescu. digital.library.unt.edu/ark:/67531/metadc152440/
- The Hunting Behavior of Black-Shouldered Kites (Elanus Caeruleus Leucurus) in Central Chile
- This article discusses the hunting behavior of black-shouldered kites in central Chile. Abstract: Kites of the genus Elanus are found throughout the world principally in open areas such as grasslands, sparse shrublands, and agricultural fields (Brown and Amadon 1968). Because of their characteristic hover-hunting, and their widespread distribution, these kites make interesting subjects for analyses of their hunting behavior. Such studies have been conducted in several regions, including North America (Waian and Stendall 1970, Warner and Rudd 1974, Koplin et al. 1980), Europe (Amat 1979, Heredia 1983), Africa (Tarboton 1978, Mendelsohn 1982), and Australia (Baker-Gabb 1984). However, quantitative information on the hunting behavior of South American kites was nonexistent until now, and is reported here from a locality in central Chile. digital.library.unt.edu/ark:/67531/metadc102283/
- Input Substitution in Irrigated Agriculture in the High Plains of Texas, 1970-80
- This article discusses input substitution in irrigated agriculture in the high plains of Texas. Abstract: The adaptability of irrigated agriculture in the High Plains region of Texas in the 1970-80 period is analyzed by estimating Allen partial elasticities of substitution for five key inputs (water, labor, center pivot, furrow, and wheel roll systems) used to produce two crops (cotton and grain sorghum). The results indicate that farmers have adapted to changes in a manner generally consistent with prior expectations concerning complementarity and substitutability among inputs. The output-constant price elasticity of water demand was statistically significant but relatively small (-.25). digital.library.unt.edu/ark:/67531/metadc71788/
- K-shell ionization by low-velocity ions
- This article discusses K-shell ionization by low-velocity ions. K-shell x-ray-production measurements are reported for protons, deuterons, and alpha particles incident on thin foils of copper, niobium, silver, and antimony. In the velocity range of the experiments, which correspond to 100-600 keV/u, the energy of ionization was as large as 10% of the bombarding energy. The inferred dependence of the excitation process on the projectile mass, atomic number, and energy is compared with theoretical estimates of a low-velocity ionization threshold, the binding effect, and the Coulomb-deflection effect. Precision of measurement is not great enough to discern unambiguously the threshold effect but the binding and Coulomb-deflection effects are clearly distinguished. digital.library.unt.edu/ark:/67531/metadc146600/
- K-shell x-ray production by 0.5-2.5-MeV ₄⁹Be+ ions incident upon selected elements from fluorine to potassium
- This article discusses K-shell x-ray production by 0.5-2.5-MeV ₄⁹Be+ ions incident upon selected elements from fluorine to potassium. Abstract: K-shell x-ray production cross sections are reported for ₄⁹Be+ ions incident upon thin ₉F, ₁₁Na, ₁₃Al, ₁₄Si, ₁₅P, ₁₇Cl, and ₁₉K targets. Incident-beam energies range from 0.5 to 2.5 MeV. It is found that the first Born approximation (plane-wave Born approximation plus the Oppenheimer-Brinkman-Kramers treatment by Nikolaev) greatly overpredicts the data, while the predictions of the perturbed-stationary-state theory with energy-loss, Coulomb deflection, and relativistic corrections (ECPSSR) are generally in good agreement with the data. There is a low-velocity discrepancy between the data and the ECPSSR predictions which may be due to multiple ionization effects on the fluorescence yields used to convert total ionization to x-ray production cross sections. digital.library.unt.edu/ark:/67531/metadc139490/
- M-shell x-ray production cross sections for 0.5-2.5-MeV Be+ ions incident upon selected elements from praseodymium to bismuth
- This article discusses M-shell x-ray production cross sections for 0.5-2.5-MeV Be+ ions incident upon selected elements from praseodymium to bismuth. Abstract: M-shell x-ray production cross sections are reported for ₄⁹Be+ ions incident upon thin ₅₉Pr, ₆₀Nd, ₆₃Eu, ₆₆Dy, ₆₇Ho, ₇₂Hf, ₇₄W, ₇₉Au, ₈₂Pb, and ₈₃Bi targets. Incident-beam energies range from 0.5 to 2.5 MeV (55.6-267 keV/u). The results are compared to the predictions of the first-Born-approximation theory and the perturbed-stationary-state theory with energy-loss, Coulomb-deflection, and relativistic corrections (ECPSSR). The first-Born-approximation theory overpredicts the measured cross sections everywhere, especially at high energies, while the ECPSSR theory tends to underpredict them, especially at low energy. This discrepancy between the measurements and the ECPSSR theory may be due in part to multiple-ionization effects which could change the fluorescence yields from the single-hole values used to convert total ionization to x-ray production cross sections in the theoretical calculations. digital.library.unt.edu/ark:/67531/metadc146598/
- M-shell x-ray production cross sections in thin targets of Au, Pb, Bi, and U by 0.3 - 2.6-MeV ₁¹H+ and ₂⁴He+ ions
- This article discusses M-shell x-ray-production cross sections in thin targets. Abstract: M-shell x-ray-production cross sections are reported for ₁¹H+ and ₂⁴He+ ions incident on thin targets of ₇₉Au, ₈₂Pb, ₈₃Bi, and ₉₂U. The energy of the ions ranged from 0.3 to 2.6 MeV in increments of 0.1 MeV. The first Born calculations overpredict the data at all energies studied. The perturbed-stationary-state calculations with energy loss, Coulomb deflection, and relativistic effects agree with the present data for both ₁¹H+ and ₂⁴He+ ions at ~0.35 MeV/u, overpredict the data at higher E₁/A₁, and underpredict the data at lower E₁/A₁. The electron-capture contribution to the target ionization is calculated to be less than 3.4% for the targets, projectiles, and energies reported in this work. digital.library.unt.edu/ark:/67531/metadc139483/
- Multiple outer-shell ionization effect in inner-shell x-ray production by light ions
- This article discusses multiple outer-shell ionization effect in inner-shell x-ray production by light ions. Abstract: L-shell x-ray production cross sections by 0.25-2.5-MeV ₂⁴He+ ions in 28Ni, 29Cu, 32Ge, 33As, 37Rb, 38Sr, 39Y, 40Zr, and 46Pd are reported. The data are compared to the first-Born approximation and the ECPSSR theory that accounts for the projectile energy loss (E) and Coulomb deflection (C) as well as the perturbed-stationary-state (PSS) and relativistic (R) effects in the treatment of the target L-shell electron. Surprisingly, the first Born approximation appears to converge to the data while the ECPSSR predictions underestimate them in the low-velocity limit. This is explained as the result of improper use of single-hole fluorescence yields. A heuristic formula is proposed to account for multiple ionizations in terms of a classical probability for these phenomena and, after it is applied, the ECPSSR theory of L-shell ionization is found to be in good agreement with the data. digital.library.unt.edu/ark:/67531/metadc139495/
- Polycyclic Aromatic Hydrocarbon Solute Probes Part II. Effect of Solvent Polarity on the Fluorescence Emission Fine Structures of Coronene Derivatives
- This article discusses the effect of solvent polarity on the fluorescence emission fine structures of coronene derivatives. Abstract: The fluorescence properties of coronene (Co), benzo[a]coronene (BCo), naphtho[2,3-a]coronene (NCo), dibenzo[a,j]coronene (DCo), naphtho[1,2,3,4-ghi]perylene, benzo[pqr]naphtho[8,1,2-bcd]perylene and dibenzo[cd,lm]perylene dissolved in solvents of varying polarity are reported. Measurements indicated that the emission intensities of the four coronene derivatives depended on solvent polarity. The Co, BCo and NCo scales have been defined as the ratio of the fluorescence intensities of bands I and III of the vibronic spectra. Band III of dibenzo[a,j]coronene was not clearly identifiable in all the solvents studied, and the DCo scale was therefore defined as the intensity ratio of band I and IV. Emission intensity ratios of the three perylene derivatives remained nearly constant, irrespective of solvent polarity. digital.library.unt.edu/ark:/67531/metadc157299/
- Rapid isothermal anneal of 75As implanted silicon
- This article discusses rapid isothermal anneal of 75As implanted silicon. Silicon wafers implanted with 75As have been annealed with a Varian IA-200 isothermal annealer. The anneal occurs in vacuum using radiation from a resistively heated sheet of graphite. The anneal quality depends on the graphite heater temperature and exposure time. If the anneal time is too short implantation damage remains and if the time is too long measurable losses of as occur causing the sheet resistance to increase. The loss of As can be prevented by depositing 0.05 μm of SiO2 on the wafer before annealing. digital.library.unt.edu/ark:/67531/metadc139471/
- Rapid isothermal annealing of As-, P-, and B-implanted silicon
- This article discusses rapid idothermal annealing of As-, P-, and B-implanted silicon. Single-crystal silicon wafers have been implanted with As, P, and B to doses of 1x1013–1x1016/cm2 and given a transient anneal using a Varian IA-200 Rapid Isothermal Annealer. The system uses infrared radiation to heat the wafers to temperatures in excess of 1000 °C for times on the order of 10 sec. Sheet resistance and Hall measurements have been used to determine the effect of the anneal on the electrical properties of the wafers. Rutherford backscattering and secondary ion mass spectroscopy have been used to measure lattice damage and dopant profiles before and after annealing. As and P are lost during the anneal unless the wafer is capped. Complete activation can be achieved with very little dopant diffusion. Residual damage is minimal in (100) oriented wafers that had been implanted with As. However, for (111) wafers damage is less in (111) wafers implanted to doses ≤5.0x1015/cm2. The diffusion of As during this transient anneal has been modeled using a concentration enhanced diffusion coefficient and the wafer temperature profile obtained from an optical pyrometer. digital.library.unt.edu/ark:/67531/metadc139472/
- Remote Sensing and GIS for Nonpoint Source Pollution Analysis in the City of Dallas' Eastern Watersheds
- This report describes the findings of a study conducted on the Eastern Watersheds of Lake Lavon, Lake Ray Hubbard, Lake Tawakoni, Lake Palestine and Lake Fork, which are located within the Blackland Prairie, Post Oak Savannah and Pineywoods provinces. These watersheds are among nine that provide drinking water to Dallas, Texas. The study examines the potential benefit of "remote sensing and geographic information systems (GIS) for watershed management" in these five watersheds (p. iii). digital.library.unt.edu/ark:/67531/metadc29400/
- Remote Sensing and GIS for Nonpoint Source Pollution Analysis in the City of Dallas' Western Watersheds
- This report describes the findings of a study conducted on the watersheds of "Lake Lewisville, Lake Ray Roberts, Lake Grapevine and the Elm Fork of the Trinity River between Lake Lewisville and Frazier Dam," which are all part of the upper Trinity drainage basin (p. 31). The study examines the potential benefit of "remote sensing and geographic information systems (GIS) for watershed management" in and around Dallas, Texas (p. i). digital.library.unt.edu/ark:/67531/metadc29399/
- L-shell x-ray production cross sections of Ni, Cu, Ge, As, Rb, Sr, Y, Zr, and Pd by (0.25-2.5)-MeV protons
- In this article, L-shell x-ray production cross sections by ₁¹H+ ions are reported. The data are compared to the first Born approximation (plane-wave Born approximation for direct ionization and Oppenheimer-Brinkman-Kramers approximation for electron capture) and to the ECPSSR (energy-loss and Coulomb-deflection effects, perturbed stationary-state approximation with relativistic correction) theory. The energy of the protons ranged from 0.25 to 2.5 MeV in steps of 0.25 MeV. The targets used in these measurements were ₂₈Ni, ₂₉Cu, ₃₂Ge, ₃₃As, ₃₇Rb, ₃₈Sr, ₃₉Y, ₄₀Zr, and ₄₆Pd. The first Born theory generally agrees with the data found in the literature at high energies and overpredicts them below 1.5 MeV. The ECPSSR predictions are in better agreement with experimental cross sections. At 0.25 MeV the authors' data, however, are underestimated by this theory and tend to agree with the first Born approximation. digital.library.unt.edu/ark:/67531/metadc139485/
- Solubility of Anthracene in Binary Solvent Mixtures Containing Dibutyl Ether
- This article discusses the solubility of anthracene in binary solvent mixtures containing dibutyl ether. Abstract: Experimental solubilities are reported for anthracene in binary solvent mixtures containing dibutyl ether with n-hexane, cyclohexane, n-heptane, methylcyclohexane, n-octane, isooctane, and cyclooctane at 25 °C. Results of these measurements, combined with estimates for the excess Gibbs free energies of the binary solvents, are used to test predictive expressions derived from the nearly ideal binary solvent (NIBS) model. Expressions based on a volume fraction average of solute properties in the two pure solvents predict anthracene solubilities to within a maximum deviation of 5.1% and an overall average deviation of 2.1%. digital.library.unt.edu/ark:/67531/metadc152449/
- Solubility of Phenylacetic Acid in Binary Solvent Mixtures
- This article discusses the solubility of phenylacetic acid in binary solvent mixtures. Abstract: Solubilities are reported for phenylacetic acid at 25.0 °C in binary mixtures of carbon tetrachloride with cyclohexane, n-heptane, n-octane, or isooctane and mixtures of cyclohexane with n-heptane or isooctane. The results are compared to the predictions of equations developed previously for solubility in systems of purely nonspecific interactions, with phenylacetic acid considered as either monomeric or dimeric molecules in solution. The dimer model provided the more accurate predictions and described the 15-fold range of solubilities in the carbon tetrachloride + isooctane system to within a maximum deviation of 15%. digital.library.unt.edu/ark:/67531/metadc152445/
- Solubility of Pyrene in Binary Solvent Mixtures Containing Cyclohexane
- This article discusses solubility of pyrene in binary solvent mixtures containing cyclohexane. Abstract: Solubilities are reported for pyrene at 26.0 °C in binary mixtures of cyclohexane with n-hexane, n-heptane, n-octane, isooctane, and cyclooctane. The results of these measurements are compared to the predictions of equations developed previously for solubility in systems of nonspecific interactions. The nearly ideal binary solvent (NIBS) model predicts these solubilities with a maximum deviation of 4.8%, using as input data the solubility of pyrene in each pure solvent. The NIBS model correctly predicts a small maxima for the mole fraction solubility of pyrene in cyclohexane + n-heptane mixtures. digital.library.unt.edu/ark:/67531/metadc152448/
- Solubility of Pyrene in Binary Solvent Mixtures Containing Dibutyl Ether
- This article discusses the solubility of pyrene in binary solvent mixtures containing dibutyl ether. Experimental solubilities are reported for pyrene in binary solvent mixtures containing dibutyl ether with n-hexane, cyclohexane, n-heptane, methylcyclohexane, n-octane, isooctane, and tert-butylcyclohexane at 26 °C. Results of these measurements, combined with estimates for the excess Gibbs free energies of the binary solvents, are used to test predictive expressions derived from the nearly ideal binary solvent (NIBS) model. Expressions based on a volume fraction average of solute properties in the two pure solvents predict pyrene solubilities to within a maximum deviation of 10% and an overall average deviation of 3.2%. digital.library.unt.edu/ark:/67531/metadc152453/
- Thermal annealing behavior of an oxide layer under silicon
- This article discusses the thermal annealing behavior of an oxide layer under silicon. High resolution Rutherford backscattering spectrometry and ion channeling have been employed to evaluate the crystallinity of the surface silicon layer in oxygen implanted silicon. The quality of the top surface layer was determined by measuring the minimum yields along 〈110〉 directions in channeling spectra. Single crystal (100) silicon was implanted with 300 keV O2+ to a dose of 1.06 X 10(18) O2+/cm2. Measurements of residual damage of the top layer were made after annealing the samples at 1150 ˚C for times ranging from 10 to 240 min in either Ar or N2. Under the implantation conditions used in this experiment, a uniform oxide layer 0.52 μm thick was buried under a top silicon layer 0.17 μm thick. The buried oxide layer has abrupt silicon to oxide interfaces. The highest quality silicon surface layer was produced after 3-h annealing in an Ar ambient. A lesser quality silicon surface layer was produced by annealing for shorter times or for equivalent times in N2 ambient. digital.library.unt.edu/ark:/67531/metadc139474/
- Thermochemical Investigations of Gas-Liquid Chromatography. Partition Coefficients of Inert Solutes on Self-Associating Binary Solvent Mixtures
- This article discusses partition coefficients of inert solutes on self-associating binary solvent mixtures. Abstract: A conventional nonelectrolyte solution model which has led to successful predictive equations for the partial molar excess properties of a solute in simple binary solvent systems is extended to include self-associating solvent components. An expression is developed and tested for its ability to describe gas-liquid partition coefficients in mixed solvents from measurements in the pure solvents. For n-hexane, n-heptane, and cyclohexane on blended mixtures of n-hexadecane and n-octadecane with N,N-dibutyl-2-ethylhexylamide, the newly derived expression is found to describe the chromatographic data to within 2%. digital.library.unt.edu/ark:/67531/metadc152444/
- Urban Water Demand Estimates Under Increasing Block Rates
- This article discusses urban water demand estimates under increasing block rates. A residential water demand equation is estimated using the only data set on water consumption that contains time series (monthly) observations on individual customers facing an increasing block rate schedule. Because the price of water both determines, and is determined by, usage, ordinary least squares estimation will yield biased estimates. Thus, two-stage least squares and instrumental variables techniques are used. The estimated coefficients on lawn size, weather, house size, and income have the expected signs and are statistically significant. However, there is not any significant response to changes in water price, perhaps due to the relatively low cost of water. digital.library.unt.edu/ark:/67531/metadc71792/
- Varietăţi Grassmanniene Mixte
- This article discusses mixed Grassmann manifolds. Abstract: Se construieşte varietea grassmanniană modelată intr-un spaţiu Banach mixt, situaţie ce generalizează simultan conceptele grassmanniene real şi complex. digital.library.unt.edu/ark:/67531/metadc161697/