680 Matching Results

Search Results

Advanced search parameters have been applied.

Infrared Studies of Anions of Barbituric Acids

Description: As long ago as 1881, it was realized that a functional group of atoms in a molecule would cause an absorption band to appear at a particular frequency in the infrared spectrum of the molecule. In more recent years, the concept of characteristic group frequencies has become firmly established and has resulted in the present widespread use of infrared spectroscopy. There appear to have been relatively few studies of infrared absorption of organic acids as compared with their salts.
Date: August 1960
Creator: Barnhart, Richard Lee
Partner: UNT Libraries

Methods Development for Simultaneous Determination of Anions and Cations by Ion Chromatography

Description: The problem with which this research is concerned is the determination of inorganic anions and cations with single injection ion chromatography. Direct detection of the separated analyte ions occurs after the analyte ions have passed through ion-exchange resins where they are separated according to their affinity for the ion-exchange resin active sites. The techniques involve the use of essentially a non-suppressed ion chromatographic system followed by a suppressed ion chromatographic system. With this system it is possible to accomplish both qualitative and quantitative determinations.
Date: May 1987
Creator: Jones, Vonda K. (Vonda Kaye)
Partner: UNT Libraries

The Effects of Common Electrolytes on Growth and Development of Selected Species of Aquatic Actinomycetes

Description: The role that aquatic actinomycetes play, in the production of tastes and odors in water supplies has been investigated since 1948. The ability of these organisms to produce by-products in lakes and streams, which renders the water unpalatable, is of considerable public health importance. It is desirable that the waterworks industry has as much information as possible concerning the factors that contribute to the growth of these organisms. Since it appears that the aquatic actinomycetes may be isolated from most fresh-water sources, the problem of diversified environments and nutritional requirements offers an excellent field of investigation. The fresh-waters of the world contain variable quantities of electrolytes that may determine in part the biological activity of these organisms. The unsolved questions in this instance are concerned with the electrolytes present and their quantitative effects on the growth and development of these forms.
Date: August 1959
Creator: Sissom, Stanley L.
Partner: UNT Libraries

Synthesis and physico-chemical properties of ionic liquidscontaining tetrakis(perfluorophenyl)borate, tetraphenylborate andtrifluorophenylborate anions.

Description: Synthesis and some physico-chemical properties are reported for six new hydrophobic ionic liquids containing tetrakis(perfluorophenyl)borate, tetraphenylborate or trfluorophenylborate anions and imidazolium or pyridinium cations.
Date: March 1, 2006
Creator: Papaiconomou, Nicolas; Salminen, Justin; Yakelis, Neal & Prausnitz, John M.
Partner: UNT Libraries Government Documents Department

A System for Measurement of Negative-Ion Charge-Exchange Cross Sections

Description: A radio-frequency positive-ion source and a fifty-kilovolt linear accelerator were designed and constructed in order to produce sizable quantities of hydrogen, helium, nitrogen, neon, and argon. Plans were then made to equip this ion source with charge-exchange apparatus suitable for charge-exchange cross-sectional measurements. It is the purpose of this paper to present the design of the equipment and to present operational knowledge of the equipment and of ion beams which are producible.
Date: January 1960
Creator: Wingo, Dale T.
Partner: UNT Libraries

Anion solvation in alcohols

Description: Anion solvation is measured in alcohols using pump-probe pulse radiolysis and the activation energy of solvation is determined. Solvation of an anion appears to be different than excited state solvation. The continuum dielectric model does not appear to explain the results.
Date: March 1996
Creator: Jonah, C. D.; Xujia, Zhang & Lin, Yi
Partner: UNT Libraries Government Documents Department

Calculations of the Relative Energies of the 2B1g and 2A2u States of Cyclobutanetetraone Radical Cation and Radical Anion Provide Further Evidence of a 3B2u Ground State for the Neutral Molecule: A Proposed Experimental Test of the Prediction of a Triplet Ground State for (CO)4

Description: Article on a proposed experimental test of the prediction of a triplet ground state for (CO)4.
Date: 2010
Creator: Zhou, Xin; Hrovat, David A. & Borden, Weston T.
Partner: UNT College of Arts and Sciences

Experimental and theoretical studies of solvation of ions

Description: Solvents determine the outcome of many industrial chemical reactions. Sometimes small changes in the properties of the solvent system can have dramatic consequences on the economics of these processes, and a broad array of empirical analyses have been performed to evaluate solvent effects on chemical processes. Chemists at Argonne National Laboratory have adopted a very direct approach and are measuring the actual rates of salvation of large organic anions in different solvents for the first time. Chuck Jonah and Yi Lin used the Argonne linac to create the anions in an unsolvated state, and then studied the manner in which they interacted with surrounding molecules. They showed that anion salvation occurs at a much faster rate than had been predicted, and they provided a theoretical understanding of the way in which the reaction rates intimately depend upon the chemical structures of the solvents. These experiments, which provide new insight into this important aspect of chemistry, were carried out using the Argonne picosecond linac and the stroboscopic pulse radiolysis system.
Date: March 1996
Creator: Jonah, C. D. & Lin, Yi
Partner: UNT Libraries Government Documents Department

Separation of Metal Ions by Anion Exchange in Mixtures of Hydrochloric Acid and Hydrofluoric Acid

Description: Distribution coefficients were determined for the adsorption of more than 40 elements on anion-exchange resins from mixtures of HCl (0.1 to 12M) and HF (0.1-8M). Two resins, Dowex 1 x 10, 200 to 400 mesh and Dowex 1 x 4, 100 to 200 mesh, were used. Distribution coefficients were also determined for the adsorption of many elements on both resins from 0.1 to 12M HCl and 0.1 to 12M HF. Anion exchange in the presence of HF was found useful for separating impurities from various materials for their subsequent determination, and specific procedures used in our spectrochemical laboratory for this purpose are outlined. The results of a literature search on the use of anion exchange in hydrofluoric acid and fluoride-containing media are presented in an extensive bibliography.
Date: December 1978
Creator: Faris, J. P.
Partner: UNT Libraries Government Documents Department

Detector Comparison for Simultaneous Determination of Organic Acids and Inorganic Anions

Description: The research reported here is a study of detector systems to determine those most suited for simultaneous organic acid, inorganic anion determination. Comparisons are made on the basis of detection limits and sensitivities for conductivity, UV/Vis, photoconductivity, and derivative conductivity detection systems. The investigation was made using a constant chromatographic system with the only variable component being the detector system. Eluant optimization conditions for each detector are reported along with tables reporting detection limits and sensitivities for each detector system. Various chromatograms are also shown to provide a visual comparison between detector results.
Date: August 1988
Creator: Pannell, Daniel K. (Daniel Kirk)
Partner: UNT Libraries

Structural simulations of nanomaterials self-assembled from ionic macrocycles.

Description: Recent research at Sandia has discovered a new class of organic binary ionic solids with tunable optical, electronic, and photochemical properties. These nanomaterials, consisting of a novel class of organic binary ionic solids, are currently being developed at Sandia for applications in batteries, supercapacitors, and solar energy technologies. They are composed of self-assembled oligomeric arrays of very large anions and large cations, but their crucial internal arrangement is thus far unknown. This report describes (a) the development of a relevant model of nonconvex particles decorated with ions interacting through short-ranged Yukawa potentials, and (b) the results of initial Monte Carlo simulations of the self-assembly binary ionic solids.
Date: October 1, 2010
Creator: van Swol, Frank B. & Medforth, Craig John (University of New Mexico, Albuquerque, NM)
Partner: UNT Libraries Government Documents Department

Metal-insulator transition by isovalent anion substitution in Ga1-xMnxAs: Implications to ferromagnetism

Description: We have investigated the effect of partial isovalent anion substitution in Ga1-xMnxAs on electrical transport and ferromagnetism. Substitution of only 2.4percent of As by P induces a metal-insulator transition at a constant Mn doping of x=0.046 while the replacement of 0.4 percent As with N results in the crossover from metal to insulator for x=0.037. This remarkable behavior is consistent with a scenario in which holes located within an impurity band are scattered by alloy disorder in the anion sublattice. The shorter mean free path of holes, which mediate ferromagnetism, reduces the Curie temperature TC from 113 K to 60 K (100 K to 65 K) upon the introduction of 3.1 percent P (1percent N) into the As sublattice.
Date: February 7, 2008
Creator: Stone, P. R.; Alberi, K.; Tardif, S. K. Z.; Beeman, J. W.; Yu, K. M.; Walukiewicz, W. et al.
Partner: UNT Libraries Government Documents Department

Pysico-chemical properties of hydrophobic ionic liquids containing1-octylpyridinium, 1-octyl-2-methylpyridinium or1-octyl-4-methylpyridinium cations

Description: This paper reports synthesis of some ionic liquids based on cations 1-octylpyridinium, 1-octyl-2-methylpyridinium or 1-octyl-4-methylpyridinium and anions dicyanamide [N(CN)2]-, bis(trifluoromethylsulfonyl)imide [Tf2N]-, bis(pentafluoroethylsulfonyl)imide [BETI]-, trifluoromethyl sulfonate [TfO]-, nonafluorobutyl sulfonate [NfO]-, tetrafluoroborate [BF4]-, trifluorophenylborate [BF3Ph]- or hexafluoroarsenate [AsF6]-. Melting points, decomposition temperatures, densities, mutual solubilities with water, and viscosities have been measured. Unlike similar ionic liquids containing imidazolium cations, pyridinium ionic liquids studied here are nearly immiscible in water. Viscosities are similar and water content is slightly lower than those for ionic liquids containing imidazolium cations.
Date: September 15, 2006
Creator: Papaiconomou, Nicolas; Salminen, Justin; Lee, Jong-Min & Prausnitz, John M.
Partner: UNT Libraries Government Documents Department

Layered Double Hydroxides as Anion- and Cation-Exchanging Materials

Description: Layered double hydroxides (LDH) have been principally known as anion-exchanging, clay-like materials for several decades, and continues to be the main driving force for current and future research. The chemical interactions of LDH, with transition metallocyanides, have been a popular topic of investigation for many years, partly due to the use of powder x-ray diffraction and infrared spectroscopy as the main characterization tools. Each transition metallocyanide has a characteristic infrared stretching frequency that can be easily observed, and their respective sizes can be observed while intercalated within the interlayer of the LDH. The ability of LDH to incorporate metal cations or any ions/molecules/complexes, that have a postive charge, have not been previously investigated, mainly due to the chemical and physical nature of LDH. The possibility of cationic incorporation with LDH would most likely occur by surface adsorption, lattice metal replacement, or by intercalation into the LDH interlayers. Although infrared spectroscopy finds it main use through the identification of the anions incorporated with LDH, it can also be used to study and identify the various active and inactive bending and stretching modes that the metal hydroxide layers have.
Date: May 2007
Creator: Richardson, Mickey Charles
Partner: UNT Libraries

The effect of iodide and pH on the adsorption of mercury(II) to illite

Description: Effect of I{sup -} concentration on mobility of Hg(II) in clay suspensions was studied over an environmentally significant pH range. The addition of I{sup -} decreased the adsorption of Hg(II), except at very low (50 {mu}g/L) I{sup -} concentrations. In suspensions of greater I{sup -} concentration (1.5 and 50 mg/L). Hg(II) adsorption increased with pH, presumably due to formation of Hg-OH complexes; at low concentrations, Hg(II) adsorption decreased with pH, presumably due to competition from hydrocomplexes for surface adsorption sites. I{sup -} was an effective extractant for Hg(II), outperforming all other halides in extraction efficiency.
Date: December 31, 1994
Creator: Hamilton, W.P.; Ghosh, M.M. & Turner, R.R.
Partner: UNT Libraries Government Documents Department

Effect of Nitrite/Nitrate concentrations on Corrosivity of Washed Precipitate

Description: Cyclic polarization scans were performed using A-537 carbon steel in simulated washed precipitate solutions of various nitrite and nitrate concentrations. The results of this study indicate that nitrate is an aggressive anion in washed precipitate. Furthermore, a quantitative linear log-log relationship between the minimum effective nitrite concentration and the nitrate concentration was established for washed precipitate with other ions at their average compositions.
Date: March 28, 2001
Creator: Congdon, J.W.
Partner: UNT Libraries Government Documents Department

Substituent Effects on Diazeniumdiolate Anions: an AB Initio and DFT Study

Description: Nitroglycerin and isoamyl nitrate have been used as nitrovasodilators since the nineteeth century. However, not until recently has it been known that these compounds were useful since they promoted the release of NO in the body. More recently, a new class of drugs, NO donors, has been developed. These include S-nitrosothiols (RSNO), sydnonimines, and nucleophilic NO adducts.
Date: December 1997
Creator: GarcĂ­a, Samuel A. (Samuel Anthony)
Partner: UNT Libraries