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The Crystal and Molecular Structures of Tri-(p-Fluorophenyl)-Amine and Tri-(p-Iodophenyl)-Amine

Description: Because of the need for data on the geometry of nitrogen in arylamines, the determination of the crystal and molecular structures of tri-(p-fluorophenyl)-amine (TFPA) and tri-(p-iodophenyl)-amine (TIPA) was undertaken as the subject of this dissertation.
Date: January 1970
Creator: Freeman, Gerald R. (Gerald Richard)
Partner: UNT Libraries

Polycyclic Aromatic Hydrocarbon Solute Probes. Part 10: Evaluation of Select Hydrogenated Pyrene, Benzo[ghi]perylene, and Naphthacene Derivatives as Possible Solvent Polarity Probes

Description: Article on polycyclic aromatic hydrocarbon solute probes and the evaluation of select hydrogenated pyrene, benzo[ghi]perylene, and naphthacene derivatives as possible solvent polarity probes.
Date: February 16, 1993
Creator: Tucker, Sheryl A. (Sheryl Ann); Acree, William E. (William Eugene); Fetzer, John Charles, 1953- & Mitchell, Reginald H.
Partner: UNT College of Arts and Sciences

Spectroscopic Investigation of Fluorescence Quenching Agents: Effect of Nitromethane on the Fluorescence Emission Behavior of Select Cyclopenta-PAH, Aceanthrylene, and Fluorene Derivatives

Description: Article on a spectroscopic investigation of fluorescence quenching agents and the effect of nitromethane on the fluorescence emission behavior of select cyclopenta-PAH, aceanthrylene, and fluorene derivatives.
Date: March 2, 1992
Creator: Amszi, Vicki L.; Cordero, Yvonne; Smith, Bradley; Tucker, Sheryl A. (Sheryl Ann); Acree, William E. (William Eugene); Yang, Chengxi et al.
Partner: UNT College of Arts and Sciences

Cryogenic Treatment of Production Components in High-Wear Rate Wells

Description: Deep Cryogenic Tempering (DCT) is a specialized process whereby the molecular structure of a material is ''re-trained'' through cooling to -300 F and then heating to +175-1100 F. Cryocon, Inc. (hereafter referred to as Cryocon) and RMOTC entered an agreement to test the process on oilfield production components, including rod pumps, rods, couplings, and tubing. Three Shannon Formation wells were selected (TD about 500 ft) based on their proclivity for high component wear rates. Phase 1 of the test involved operation for a nominal 120 calendar day period with standard, non-treated components. In Phase 2, treated components were installed and operated for another nominal 120 calendar day period. Different cryogenic treatment profiles were used for components in each well. Rod pumps (two treated and one untreated) were not changed between test phases. One well was operated in pumped-off condition, resulting in abnormal wear and disqualification from the test. Testing shows that cryogenic treatment reduced wear of rods, couplers, and pump barrels. Testing of production tubing produced mixed results.
Date: April 29, 2002
Creator: Milliken, M.
Partner: UNT Libraries Government Documents Department

Study of anisotropy of spin cast and vapor deposited polyimide films using internal reflection techniques

Description: We have compared anisotropy of spin cast and vapor deposited polyimide (VDP) films, using internal reflection infrared spectroscopy. The films were deposited directly on the internal reflection element. We find that spin cast films are more anisotropic than their VDP counterparts, with the polyimide chains tending to align parallel to the substrate. Both films are found to contain more and less ordered regions. Within the ordered regions, the plane of the phenyl ring tends to align parallel to the substrate.
Date: November 1, 1996
Creator: Liberman, V.
Partner: UNT Libraries Government Documents Department

Invariant patterns in crystal lattices: Implications for protein folding algorithms

Description: Crystal lattices are infinite periodic graphs that occur naturally in a variety of geometries and which are of fundamental importance in polymer science. Discrete models of protein folding use crystal lattices to define the space of protein conformations. Because various crystal lattices provide discretizations of the same physical phenomenon, it is reasonable to expect that there will exist invariants across lattices related to fundamental properties of the protein folding process. This paper considers whether performance-guaranteed approximability is such an invariant for HP lattice models. The authors define a master approximation algorithm that has provable performance guarantees provided that a specific sublattice exists within a given lattice. They describe a broad class of crystal lattices that are approximable, which further suggests that approximability is a general property of HP lattice models.
Date: June 1, 2000
Partner: UNT Libraries Government Documents Department

Synthesis and Characterization of a New Perhalogenated Porphyrin

Description: The first synthesis of an octahalotetraalkylporphyrin [2,3,7,8,12,13,17,18 -octabromo-5,10,15,20- tetrakis(trifluoromethyl)porphinato nickel(II)] is reported; this perhalogenated porphyrin has several novel properties including a very nonplanar ruffled structure with an unusually short Ni- N distance, an extremely red-shifted optical spectrum, and hindered rotation of the trifluoromethyl groups ({Delta}G<sub>278K</sub> =47 kJ mol<sup>-1</sup>).
Date: May 19, 1999
Creator: Jia, Songling; Medforth, Craig J.; Nelson, Nora Y.; Nurco, Daniel J.; Shelnutt, John & Smith, Kevin M.
Partner: UNT Libraries Government Documents Department

Responsive Copolymers for Enhanced Petroleum Recovery

Description: The objectives of this work was to: (1) synthesize responsive, amphiphilic systems; (2) characterize molecular structure and solution behavior; (3) measure rheological properties of the aqueous fluids including behavior in fixed geometry flow profiles and beds; and (4) to tailor polymer compositions for in situ rheology control under simulated reservoir conditions.
Date: February 27, 2002
Creator: McCormick, Charles & Hester, Roger
Partner: UNT Libraries Government Documents Department

Signature molecular descriptor : advanced applications.

Description: In this work we report on the development of the Signature Molecular Descriptor (or Signature) for use in the solution of inverse design problems as well as in highthroughput screening applications. The ultimate goal of using Signature is to identify novel and non-intuitive chemical structures with optimal predicted properties for a given application. We demonstrate this in three studies: green solvent design, glucocorticoid receptor ligand design and the design of inhibitors for Factor XIa. In many areas of engineering, compounds are designed and/or modified in incremental ways which rely upon heuristics or institutional knowledge. Often multiple experiments are performed and the optimal compound is identified in this brute-force fashion. Perhaps a traditional chemical scaffold is identified and movement of a substituent group around a ring constitutes the whole of the design process. Also notably, a chemical being evaluated in one area might demonstrate properties very attractive in another area and serendipity was the mechanism for solution. In contrast to such approaches, computer-aided molecular design (CAMD) looks to encompass both experimental and heuristic-based knowledge into a strategy that will design a molecule on a computer to meet a given target. Depending on the algorithm employed, the molecule which is designed might be quite novel (re: no CAS registration number) and/or non-intuitive relative to what is known about the problem at hand. While CAMD is a fairly recent strategy (dating to the early 1980s), it contains a variety of bottlenecks and limitations which have prevented the technique from garnering more attention in the academic, governmental and industrial institutions. A main reason for this is how the molecules are described in the computer. This step can control how models are developed for the properties of interest on a given problem as well as how to go from an output of the algorithm to ...
Date: April 1, 2010
Creator: Visco, Donald Patrick, Jr. (Tennessee Technological University, Cookeville, TN)
Partner: UNT Libraries Government Documents Department

Photo-control of nanointeractions.

Description: The manipulation of physical interactions between structural moieties on the molecular scale is a fundamental hurdle in the realization and operation of nanostructured materials and high surface area microsystem architectures. These include such nano-interaction-based phenomena as self-assembly, fluid flow, and interfacial tribology. The proposed research utilizes photosensitive molecular structures to tune such interactions reversibly. This new material strategy provides optical actuation of nano-interactions impacting behavior on both the nano- and macroscales and with potential to impact directed nanostructure formation, microfluidic rheology, and tribological control.
Date: February 1, 2005
Creator: Thomes, William Joseph, Jr.; Potter, Barrett George, Jr. (The University of Arizona, Tucson, AZ); Jiang, Liu; Long, Timothy Michael; Piech, Marcin; Jamison, Gregory Marks et al.
Partner: UNT Libraries Government Documents Department

Dynamical hierarchies - A summary

Description: This paper summarizes some of the problems associated with the generation of higher order emergent structures in formal dynamical systems. In biological systems, higher order hyperstructures occur both in an intuitive and a formal sense: monomers, polymers, membranes, organelles, cells, tissues, organs, etc. constitute an observable hierarchy, apparently generated by the underlying biomolecular process. However, in models and simulations of these systems, it has turned out to be quite difficult to produce higher order emergent structures from first principles. The first problem is to agree on what a higher order structure is. An emergent structure can be defined through an introduction of an observational function. If a property can be observed in the dynamics, but not at the level of the fundamental first order interacting structures, we define it to be emergent. It is well known that second order structures occur relatively easy in simulation, so the problem is how to proceed to third and higher order without external interference. A third order structure is defined through the interaction of second order structures forming a new observable not found at the lower levels.
Date: April 1, 1996
Creator: Rasmussen, S.; Barrett, C.L. & Olesen, M.W.
Partner: UNT Libraries Government Documents Department

DNA sequencing technology, walking with modular primers. Final report

Description: The success of the Human Genome Project depends on the development of adequate technology for rapid and inexpensive DNA sequencing, which will also benefit biomedical research in general. The authors are working on DNA technologies that eliminate primer synthesis, the main bottleneck in sequencing by primer walking. They have developed modular primers that are assembled from three 5-mer, 6-mer or 7-mer modules selected from a presynthesized library of as few as 1,000 oligonucleotides ({double_bond}4, {double_bond}5, {double_bond}7). The three modules anneal contiguously at the selected template site and prime there uniquely, even though each is not unique for the most part when used alone. This technique is expected to speed up primer walking 30 to 50 fold, and reduce the sequencing cost by a factor of 5 to 15. Time and expensive will be saved on primer synthesis itself and even more so due to closed-loop automation of primer walking, made possible by the instant availability of primers. Apart from saving time and cost, closed-loop automation would also minimize the errors and complications associated with human intervention between the walks. The author has also developed two additional approaches to primer-library based sequencing. One involves a branched structure of modular primers which has a distinctly different mechanism of achieving priming specificity. The other introduces the concept of ``Differential Extension with Nucleotide Subsets`` as an approach increasing priming specificity, priming strength and allowing cycle sequencing. These approaches are expected to be more robust than the original version of the modular primer technique.
Date: December 31, 1996
Creator: Ulanovsky, L.
Partner: UNT Libraries Government Documents Department

NMR studies of DNA oligomers and their interactions with minor groove binding ligands

Description: The cationic peptide ligands distamycin and netropsin bind noncovalently to the minor groove of DNA. The binding site, orientation, stoichiometry, and qualitative affinity of distamycin binding to several short DNA oligomers were investigated by NMR spectroscopy. The oligomers studied contain A,T-rich or I,C-rich binding sites, where I = 2-desaminodeoxyguanosine. I{center_dot}C base pairs are functional analogs of A{center_dot}T base pairs in the minor groove. The different behaviors exhibited by distamycin and netropsin binding to various DNA sequences suggested that these ligands are sensitive probes of DNA structure. For sites of five or more base pairs, distamycin can form 1:1 or 2:1 ligand:DNA complexes. Cooperativity in distamycin binding is low in sites such as AAAAA which has narrow minor grooves, and is higher in sites with wider minor grooves such as ATATAT. The distamycin binding and base pair opening lifetimes of I,C-containing DNA oligomers suggest that the I,C minor groove is structurally different from the A,T minor groove. Molecules which direct chemistry to a specific DNA sequence could be used as antiviral compounds, diagnostic probes, or molecular biology tools. The author studied two ligands in which reactive groups were tethered to a distamycin to increase the sequence specificity of the reactive agent.
Date: May 1, 1996
Creator: Fagan, P.A.
Partner: UNT Libraries Government Documents Department

Advance concepts for conversion of syngas to liquids. Quarterly report No. 3, April 29, 1995--July 28, 1995

Description: The aim of this phase of our study is to demonstrate how cobalt-containing aluminophosphate molecular sieves with structure types AFI and AEL can be synthesized from a clear homogeneous solution. The advantage of beginning with a clear solution is that transient phases, either crystalline or amorphous, can be more easily identified. The nature of these phases and their role in the crystallization process can be seen more easily. HF is used as a mineralizing agent. It has been reported that the presence of F anions in the synthesis mixture can improve considerably the AlPO{sub 4}-5 type crystals.
Date: December 1, 1995
Creator: Szostak, R.; Abotsi, G. & Mitchell, M.
Partner: UNT Libraries Government Documents Department

Bioorganometallic Chemistry, Part 15. A novel molecular recognition process of host, trans-[Cp*Rh({eta}{sup 1}(N3)-1-methylcytosine)({mu}-OH)]{sub 2} (OTf){sub 2}, with l-aromatic amino acid guests: selective hydrogen bonding to the {mu}-OH groups and the 1-methylcytosine ligands

Description: The {sup 1}H-NMR and computer docking experiments have elucidated a novel molecular recognition process of host, trans-[Cp*Rh({eta}{sup 1}(Ne)-1-methylcytosine)({mu}-OH)]{sub 2}(OTf){sub 2} (1), with L-aromatic amino acids, which is predicated on a selective hydrogen bonding regime of the NH{sub 3}{sup +} of the amino acid to one of the Rh-{mu}-OH groups, as well as to a C{double_bond}O group of one of the other 1-methycytosine ligands, while the COO{sup -} H-bonds to an NH{sub 2} of the other 1-methycytosine ligand.
Date: November 1, 2002
Creator: Elduque, Anabel; Carmona, Daniel; Oro, Luis; Eisenstein, Miriam & Fish, Richard H.
Partner: UNT Libraries Government Documents Department

The structure of carbon black and its composites with elastomers: A study using neutron scattering

Description: The authors have been exploring the use of small-angle neutron scattering and the method of contrast variation to give a new look at a very old problem--reinforcement of elastomers by carbon black in durable rubber products. The method has yielded some interesting information on the structure of an experimental carbon black, HSA, and on the associations of HSA in polyisoprene composites. Carbon black has a hierarchy of structures consisting of particles covalently bound into aggregates, which in turn associate by weak interactions into agglomerates. The authors found that in HSA the aggregates are rodlike, containing an average of 4--6 particles. The aggregates have an outer graphitic shell and an inner core of lower density carbon. The core is continuous throughout the carbon black aggregate. Contrast variation of swollen HSA-polyisoprene gels show that the HSA is completely embedded in polyisoprene and that the agglomerates are formed predominantly by end on associations of the rodlike aggregates. The surface structure of the carbon black appears smooth over length scales above about 10 {angstrom}. Further studies on production carbon blacks suggest that the shell-like aggregate structure is present in commercial carbon blacks.
Date: July 1, 1996
Creator: Hjelm, R.P.; Wampler, W. & Gerspacher, M.
Partner: UNT Libraries Government Documents Department

Mechanisms of protein and virus crystal growth: An atomic force microscopy study of canavalin and STMV crystallization

Description: The evolution of surface morphology and step dynamics during growth of rhombohedral crystals of the protein canavalin and crystals of the cubic satellite tobacco mosaic virus (STMV) have been investigated for the first time by in situ atomic force microscopy. These two crystals were observed to grow by very different mechanisms. Growth of canavalin occurs on complex vicinal hillocks formed by multiple, independently acting screw dislocations. Small clusters were observed on the terraces. STMV on the other hand, was observed to grow by 2D nucleation of islands. No dislocations were found on the crystal. The results are used to determine the growth mechanisms and estimate the fundamental materials parameters. The images also illustrate the important mechanism of defect incorporation and provide insight to the processes that limit the growth rate and uniformity of these crystals.
Date: May 1996
Creator: Land, T. A.; De Yoreo, J. J.; Malkin, A. J.; Kutznesov, Yu. G. & McPherson, A.
Partner: UNT Libraries Government Documents Department

Molecular accessibility in oxidized and dried coals. Quarterly report, July 1995--September 1995

Description: The objective of this research project is to determine the molecular and structural changes that occur in swelled coal as a result of oxidation and moisture loss both in the presence and absence of light using our newly developed EPR spin probe method. The proposed study will make it possible to deduce the molecular accessibility distribution in swelled, oxidized APCS coal for each rank as a function of (1) size (up to 6 nm) and shape, (2) the relative acidic/basic reactive site distributions, and (3) the role of hydrogen bonding as a function of swelling solvents. The advantage of the EPR method is that it permits molecules of selected shape, size and chemical reactivity to be used as probes of molecular accessible regions of swelled coal. From such data an optimum catalyst can be designed to convert oxidized coal into a more convenient form and methods can be devised to lessen the detrimental weathering processes.
Date: February 1, 1996
Creator: Kispert, L.D.
Partner: UNT Libraries Government Documents Department

Reaction chemistry of cerium

Description: It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.
Date: January 1, 1997
Partner: UNT Libraries Government Documents Department