895 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "chemistry"  
Results: 1 - 24 next
open access

Low Temperature Thermoluminescence of Gamma Irradiated Potassium Dihydrogen Phosphate

Description: Thermoluminescence in potassium dihydrogen phosphate (KDP) induced by Co/ sup 60/ gamma irradiation at liquid nitrogen temperature (-198 deg C) was investigated. Glow curves in the temperature range --196 to 0 deg C were measured for a series of gamma exposure dosages ranging from 10/sup 4/ roentgen to 5 x 10/sup 6/ roentgen. The heating rate used for glow curve measurements was 12 deg C per minute. Twice recrystallized Mallinckrodt reagent grade potassium dihydrogen phosphate, with a grain siz… more
Date: October 19, 1962
Creator: Sims, T. M.
Partner: UNT Libraries Government Documents Department
open access

The Specific Heat of Dysprosium Metal Between 0.4 and 4 K

Description: Submitted to Illinois Inst. of Tech., Chicago. A He/sup 3/ cryostat was built to measure the specific heat of rare earth metals which have a component, at low temperatures, attributable to the electrons in the incomplete 4f shell. The specific heat of dysprosium from 0.4 to 4.2 deg K was measured. Pertinent theories about specific heats are outlined. The apparatus included the cryostat, vacuum and He/sup 3/ systems, calorimeter, carbon thermometer, heater, and magnetic thermometer. The experime… more
Date: August 1, 1962
Creator: Guenther, R. A.
Partner: UNT Libraries Government Documents Department
open access

Synthesis and characterization of an N-(2-hydroxyethyl)-ethylenediaminetriacetic acid resin

Description: A chelating ion-exchange resin with N-(2-hydroxyethyl)ethylene-diaminetriacetic acid (HEDTA) used as the ligand chemically bonded to XAD-4 by an ester linkage, HEDTA-4, was synthesized. It is stable under normal experimental conditions with the liquid chromatograph. The structure of the resin was confirmed by an infrared spectrum, and by potentiometric titrations. The capacity of the resin was also obtained by potentiometric titration and by a nitrogen analysis. The resin was used to pack a col… more
Date: October 1, 1977
Creator: Lai, Y. F.
Partner: UNT Libraries Government Documents Department
open access

Electron microscopy of hydrocarbon production in parthenium argentatum (guayule)

Description: The electron microscope was used to study the biological processes involved in hydrocarbon production. The little desert shrub Guayule (Parthenium argentatum) was selected for study. This shrub can produce hydrocarbons (rubber) in concentrations up to 1/4 of its dry weight. It grows on semi-arid land and has been extensively studied. The potential of Guayule is described in detail. Results of an investigation into the morphology of Guayule at the electron microscope level are given. Experiments… more
Date: November 1, 1977
Creator: Bauer, T.E.
Partner: UNT Libraries Government Documents Department
open access

Kinetic Studies of the Reactions Occurring Between Tungsten and Gases at Low Pressure and High Temperatures

Description: Oxygen, nitrogen, and nitric oxide gases were passed through a system consisting of a tungsten filament, an ion gauge, and a mass spectrometer. The ion gauge recorded total pressures and the spectrometer recorded partlal pressures of O/sub 2/, N/sub 2/, NO, CO, COa, and H/sub 2/O. From the way these pressures changed with filamert temperature, the rates of conversion of O/sub 2/ to volatile tungsten oxides and O, and of NO to volatile tungsten oxides N/sub 2/ , O/sub 2/, and O were computed. Th… more
Date: April 1, 1962
Creator: Anderson, H. U.
Partner: UNT Libraries Government Documents Department
open access

Use of a semiconductor laser in infrared spectroscopy

Description: A semiconductor laser has certain properties which makes its use desirable as a continuous monitor of atmospheric pollutants. Its energy output is concentrated in widely separated energy modes of very narrow bandwidths (less than 10/sup -5/ cm/sup -1/) which can be centered on one infrared absorption line of one gas. This makes the laser quite selective. The energy in each mode is typically greater than 200 ..mu.. watts, and, because of the laser's small size, its light energy can be colli… more
Date: December 1, 1977
Creator: Morris, R. N.
Partner: UNT Libraries Government Documents Department
open access

Inductively coupled plasma--atomic emission spectrometry: trace elements in oil matrices

Description: The simultaneous determination of up to 20 trace elements in various oil matrices by inductively coupled plasma-atomic emission spectrometry is reported. The oil matrices investigated were lubricating oils (for wear metals), fuel oil, centrifuged coal liquefaction product, crude soybean oil, and commercial edible oils. The samples were diluted with appropriate organic solvents and injected into the plasma as an aerosol generated by a pneumatic nebulization technique. Detection limits of the 28 … more
Date: December 1, 1977
Creator: Peterson, C. A.
Partner: UNT Libraries Government Documents Department
open access

Analytical applications of resins containing amide and polyamine functional groups

Description: A dibutyl amide resin is used for the separation of uranium(VI), thorium(IV), and zirconium(IV) from each other and several other metal ions. Uranium(VI) and thorium(IV) are determined in the presence of large excesses of foreign metal ions and anions. A practical application of the amide resin is studied by determining uranium in low grade uranium ores. The amide resin is also used for the selective concentration of gold(III) from sea water.
Date: December 1, 1977
Creator: Orf, G. M.
Partner: UNT Libraries Government Documents Department
open access

Lanthanide extraction with 2,5-dimethyl-2-hydroxyhexanoic acid

Description: This research is concerned with the solvent extraction into chloroform of the lanthanides, using 2,5-dimethyl-2-hydroxyhexanoic acid (DMHHA). This acid is the first ..cap alpha..-hydroxy aliphatic acid to be studied as an extracting agent for the lanthanides. The chloroform-water DMHHA partition constant was determined to be 1.0 (at 0.1 M ionic strength and 25/sup 0/C). The acid dimerizes in chloroform with a constant of 56. The light lanthanides can be extracted into chloroform by forming comp… more
Date: December 1, 1977
Creator: Miller, J. H.
Partner: UNT Libraries Government Documents Department
open access

Stability of Myosin Subfragment-2 Modulates the Force Produced by Acto-Myosin Interaction of Striated Muscle

Description: Myosin subfragment-2 (S2) is a coiled coil linker between myosin subfragment-1 and light meromyosin (LMM). This dissertation examines whether the myosin S2 coiled coil could regulate the amount of myosin S1 heads available to bind actin thin filaments by modulating the stability of its coiled coil. A stable myosin S2 coiled coil would have less active myosin S1 heads compared to a more flexible myosin S2 coiled coil, thus causing increased force production through acto-myosin interaction. The … more
Date: December 2017
Creator: Singh, Rohit Rajendraprasad
Partner: UNT Libraries
open access

Heated uranium tetrafluoride target system to release non-rare gas fission products for the TRISTAN isotope separator. [As replacement for uranyl stearate]

Description: Off-line experiments indicated that fluorides of As, Se, Br, Kr, Zr, Nb, Mo, Tc, Ru, Sb, Te, I and Xe could be volatilized, but except for Br, Kr, I and Xe, none of these elements were observed after mass separation in the on-line experiments. The results of the on-line experiments indicated a very low level of hydride contamination at ambient temperature and consequently, uranium tetrafluoride replaced uranyl stearate as the primary gaseous fission product target. Possible reasons for the fail… more
Date: October 1, 1977
Creator: Gill, R. L.
Partner: UNT Libraries Government Documents Department
open access

Thermodynamic Properties of Nonelectrolyte Solutes in Ternary Solvent Mixtures

Description: The purpose of this dissertation is to investigate the thermodynamic properties of nonelectrolyte solutes dissolved in ternary solvent mixtures, and to develop mathematical expressions for predicting and describing that behavior in the solvent mixtures. Thirty-four ternary solvent systems were studied containing either alcohol (1-propanol, 2-propanol, 1-butanol, and 2-butanol), alkane (cyclohexane, heptane, and 2,2,4-trimethylpentane) or alkoxyalcohol (2-ethoxyethanol and 2-butoxyethanol) cosol… more
Date: August 1999
Creator: Deng, Tʻai-ho
Partner: UNT Libraries
open access

Interactions of Clean and Sulfur-modified Reactive Metal Surfaces with Aqueous Vapor and Liquid Environments : A Combined Ultra-high Vacuum/electrochemistry Study

Description: The focus of this research is to explore the molecular-level interactions between reactive metal surfaces and aqueous environments by combined ultra-high vacuum/electrochemistry (UHV-EC) methodology. The objectives of this work are to understand (1) the effects of sulfate ions on the passivity of metal oxide/hydroxide surface layer, (2) the effects of sulfur-modification on the evolution of metal oxide/hydroxide surface layer, and (3) the effects of sulfur adsorbate on cation adsorption at meta… more
Date: May 1998
Creator: Lin, Tien-Chih, 1966-
Partner: UNT Libraries
open access

Discontinuous Thermal Expansions and Phase Transformations in Crystals at Higher Temperatures

Description: The purpose of this investigation is to make more detailed studies of transformations. Fourteen compounds have been examined by high temperature X-ray diffraction for this purpose. The investigations have been carried out in such a way as to reveal: 1. the existence of transformations, 2. the influence of polarizability on thermal expansion, 3. the anisotropy of expansion, and 4. the discontinuity of thermal expansion.
Date: 1967
Creator: Hsu, Yuan Tsun
Partner: UNT Libraries
Back to Top of Screen