You limited your search to:

  Partner: UNT Libraries
 Department: Department of Chemistry
 Collection: UNT Theses and Dissertations
Characterization of Low Barrier Hydrogen Bonds in Enzyme Catalysis: an Ab Initio and DFT Investigation

Characterization of Low Barrier Hydrogen Bonds in Enzyme Catalysis: an Ab Initio and DFT Investigation

Date: August 1999
Creator: Pan, Yongping
Description: Hartree-Fock, Moller-Plesset, and density functional theory calculations have been carried out using 6-31+G(d), 6-31+G(d,p) and 6-31++G(d,p) basis sets to study the properties of low-barrier or short-strong hydrogen bonds (SSHB) and their potential role in enzyme-catalyzed reactions that involve proton abstraction from a weak carbon-acid by a weak base. Formic acid/formate anion, enol/enolate and other complexes have been chosen to simulate a SSHB system. These complexes have been calculated to form very short, very short hydrogen bonds with a very low barrier for proton transfer from the donor to the acceptor. Two important environmental factors including small amount of solvent molecules that could possibly exist at the active site of an enzyme and the polarity around the active site were simulated to study their energetic and geometrical influences to a SSHB. It was found that microsolvation that improves the matching of pK as of the hydrogen bond donor and acceptor involved in the SSHB will always increase the interaction of the hydrogen bond; microsolvation that disrupts the matching of pKas, on the other hand, will lead to a weaker SSHB. Polarity surrounding the SSHB, simulated by SCRF-SCIPCM model, can significantly reduce the strength and stability of a SSHB. The residual strength ...
Contributing Partner: UNT Libraries
Characterization of Novel Solvents and Absorbents for Chemical Separations

Characterization of Novel Solvents and Absorbents for Chemical Separations

Date: May 2011
Creator: Grubbs, Laura Michelle Sprunger
Description: Predictive methods have been employed to characterize chemical separation mediums including solvents and absorbents. These studies included creating Abraham solvation parameter models for room-temperature ionic liquids (RTILs) utilizing novel ion-specific and group contribution methodologies, polydimethyl siloxane (PDMS) utilizing standard methodology, and the micelles cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) utilizing a combined experimental setup methodology with indicator variables. These predictive models allows for the characterization of both standard and new chemicals for use in chemical separations including gas chromatography (GC), solid phase microextraction (SPME), and micellar electrokinetic chromatography (MEKC). Gas-to-RTIL and water-to-RTIL predictive models were created with a standard deviation of 0.112 and 0.139 log units, respectively, for the ion-specific model and with a standard deviation of 0.155 and 0.177 log units, respectively, for the group contribution fragment method. Enthalpy of solvation for solutes dissolved into ionic liquids predictive models were created with ion-specific coefficients to within standard deviations of 1.7 kJ/mol. These models allow for the characterization of studied ionic liquids as well as prediction of solute-solvent properties of previously unstudied ionic liquids. Predictive models were created for the logarithm of solute's gas-to-fiber sorption and water-to-fiber sorption coefficient for polydimethyl siloxane for wet and dry conditions. These models ...
Contributing Partner: UNT Libraries
A Chemical Analysis of Soft Wheat

A Chemical Analysis of Soft Wheat

Date: 1940
Creator: Truitt, Jack
Description: The purpose of this piece of research is to determine the chemical composition of soft winter wheat, and to make a comparative study of it. A study is also made concerning its possibilities as a balanced food.
Contributing Partner: UNT Libraries
A Chemical Analysis of the Blackeyed Pea

A Chemical Analysis of the Blackeyed Pea

Date: 1941
Creator: Davis, Stanley F.
Description: The purpose of this research problem is to determine the chemical composition of the blackeyed pea and to make a comparative study of the results. The value of the blackeyed pea as food, its chemical nature, and possible industrial uses are studied and recorded.
Contributing Partner: UNT Libraries
Chemical Analysis of the Bottom Deposits of Artificial Lakes with Special Emphasis on Lake Dallas

Chemical Analysis of the Bottom Deposits of Artificial Lakes with Special Emphasis on Lake Dallas

Date: 1940
Creator: Patrick, Paul V.
Description: This study is for the purpose of determining the chemical content of typical artificial reservoir bottom deposits.
Contributing Partner: UNT Libraries
A Chemical Analysis of the Important Soils of Dimmit County, Texas

A Chemical Analysis of the Important Soils of Dimmit County, Texas

Date: August 1938
Creator: Meek, William
Description: The purpose of this study is to collect sample soils from uncontaminated horizon (by digging completely through the soil profile or strata) and provide a chemical analysis of the important soils of Dimmit county, Texas.
Contributing Partner: UNT Libraries
The Chemical Analysis of the Mebane Cottonseed Kernel

The Chemical Analysis of the Mebane Cottonseed Kernel

Date: 1941
Creator: Hanna, Alvis Nelson
Description: The purpose of this work is to make a fairly complete chemical analysis of the Mebane 804-50 cottonseed kernel. A brief history of cotton plant and the economic value of its products are also presented.
Contributing Partner: UNT Libraries
A Chemical Analysis of the Peanut

A Chemical Analysis of the Peanut

Date: 1940
Creator: Brown, Carlos L.
Description: The object of this paper is to make an analysis of the mineral and food content of the peanut and to compare them with a balanced food.
Contributing Partner: UNT Libraries
A Chemical Analysis of the Soils of Denton County, Texas

A Chemical Analysis of the Soils of Denton County, Texas

Date: August 1936
Creator: Wilson, Curtis
Description: The purpose of this study was to analyze the different soils in Denton, Texas. For the purpose of this study, the soils of Denton County are divided into three general groups with respect to origin: 1)those formed in place by the weathering of consolidated rocks, 2) those formed from the weathering of unconsolidated rocks, and 3) alluvial soils. A chemical analysis of representative samples of Bell Clay, Kirvin fine sandy loam, and San Saba clay has been made, and shown to have a strict correlation with their respective geological origins.
Contributing Partner: UNT Libraries
The Chemical Analysis of the Tennessee Green Pod Pole Bean

The Chemical Analysis of the Tennessee Green Pod Pole Bean

Date: 1941
Creator: Mitchell, O. R.
Description: The object of this paper is to compare the Tennessee green pod pole bean with other beans as to chemical composition and food value.
Contributing Partner: UNT Libraries