Browsing by Subject "Chemistry"
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Item A comparative study of learning styles of Hispanic and Anglo chemistry students(Texas Tech University, 1995-08) Flores-Feist, M. CeliaThe purpose of this study was to compare the learning styles of Hispanic and Anglo students enrolled in chemistry. Eight hypotheses were tested using routines available in the Statistical Package for the Social Sciences (SPSSX).Item A mechanistic study of complex base-promoted 1,2-elimination reactions(Texas Tech University, 1983-12) Croft, Alan PaulNot availableItem A polarographic investigation of the Zirconium-alizarin lake(Texas Tech University, 1952-01) Daniel, Roger LouisNot availableItem A study of epithermal neutron flux perturbation(Texas Tech University, 1961-08) Beckner, Jack LNot availableItem A study of phenothiazine, phenothiazine 5-oxide, and phenothiazone-3 in acid solutions(Texas Tech University, 1967-08) Mach, Edward EugeneNot availableItem A study of the intramolecularity of the thermal rearrangement of polynuclear aromatic hydrazo-compounds(Texas Tech University, 1960-08) Huang, Fui-TsengNot availableItem A study of the mechanism of the thermal rearrangement of 2.2'-Hydrazonaphthalene(Texas Tech University, 1959-08) Trisler, John CharlesNot availableItem A thermogravimetric study of some gas-solid reactions(Texas Tech University, 1964-08) Nesbitt, Lyle EdwinNot availableItem Advannces in ion chromatograpy for environmental applications(Texas Tech University, 2003-08) Al-Horr, Rida SadekIon chromatography (IC) is a widely used analytical tool for the determination of many ionic species. Applications of ion chromatography extend over a wide range of chemical analyses. Introduction of eluent suppression in the mid-1970s extended the boundaries of conductometric detection into trace analysis. Current state-of-the-art IC systems require only water to operate, exhibit excellent reliabilities, and provide the ability of sample preconcentration and simultaneous multiple ion measurement, making them attractive for atmospheric analysis. Atmospheric particulate matter (PM) contains many inorganic and organic soluble ions. A number of those are weak acid anions that are largely undetectable in suppressed ion chromatography. An improved method that uses sequential suppressed and unsuppressed IC for the sensitive detection of both common anions and very weak acid anions has been investigated. After suppressed conductometric detection, the effluent is passed into a membrane device where KOH is passively introduced into the eluent stream using Donnan forbidden leakage. High temporal resolution measurement of atmospheric gases and constituents of atmospheric particulate matter (PM) is important to understand the chemistry and sources of atmospheric pollution. New continuous collection devices coupled with IC systems for fully automated measurement of soluble inorganic gases and soluble ionic constituents of atmospheric PM have been developed. Soluble gas collection is accomplished with a parallel plate wet denuder (PPWD). For particle collection, an automated alternating filter-based system was initially developed. This system uses two glass-fiber filters that alternate between sampling, and washing and drying. More recently, a continuous soluble particle collector (PC) of simpler design has been developed; this device does not use steam. Preceded by a denuder and interfaced with an ion chromatograph, this compact collector permits automated collection and continuous extraction of soluble anions and ammonium ion in atmospheric particulate matter. The systems have been deployed in a number of major field studies held in urban and suburban locations in the United States.Item Alkylation of sodio-cyanoethylmalonic ester as a step in the synthesis of [Greek letter alpha]-alkylglutaric acids(Texas Tech University, 1965-05) Glover, Jimmy DaleNot availableItem An investigation of the system PbO-Cr2O3(Texas Tech University, 1961-05) Schaefer, Weldon ErnestNot availableItem Applications of triazine chemistry: education, remediation, and drug delivery(2009-05-15) Hatfield, Susan ElizabethTriazine chemistry has many applications from industrial usage, such as melamine resins, to academic interests in dendritic structures which may one day come to fruition as pharmaceutically applicable molecules. Organic synthesis, using the 1,3,5- triazine derivative 2,4,6-trichlorotriazine, cyanuric chloride, for practical applications was investigated. By utilizing the selective reactivity of cyanuric chloride, a plethora of targets from small molecules to large dendrimers may be synthesized. Triazine chemistry was adapted to an educational application for the development of an undergraduate laboratory to synthesize simazine, a widely used herbicide. The laboratory was designed to foster a sense of the applications of chemistry in the world and its effect on the environment and society. The modification of chitosan for herbicide remediation has been accomplished using triazine chemistry, as well. Treatment of chitosan iteratively with cyanuric chloride followed by piperazine produces dendritic grafts from these flakes. Dendrons of generation one through three were synthesized on chitosan backbones of low, medium, and high molecular weights. The piperazine derivatives were shown to sequester more than 99% of atrazine from an aqueous 100 ppb solution in a 24 h period. Drug delivery applications of triazine-based dendrimers were investigated. Pegylated G3 dendrimers with molecular weights of 18 and 34 kDa with 9% and 17% iodine content by weight, respectively, were synthesized as potential macromolecular contrast agents. The development of macromolecular contrast agents is of great interest to counteract the drawbacks associated with currently used, small molecule contrast media, including toxicity, extravasation into the extracellular space, and rapid clearance from the bloodstream. Dendrimers are well suited for use as macromolecular media due to the unique properties of these molecules, including monodispersity and multivalency.Item Bipolar electrodes for the screening of electrocatalyst candidates(2014-05) Fosdick, Stephen Edward; Crooks, Richard M. (Richard McConnell); Bard, Allen J; Manthiram, Arumugam; Mullins, Charles B; Stevenson, Keith JAdvances in the application of bipolar electrodes (BPEs) for screening of electrocatalysts, localized activation of a single conductive electrode, the optical tracking of single particles interacting with an active electrode, and the introduction of microwires in paper-based analytical devices are described. In an original proof of concept study arrays of BPEs were used to determine the relative activity of model nanoparticle systems for the oxygen reduction reaction (ORR) by a simple optical readout: the electrodissolution of Ag microbands. The number of bands that dissolved during the screening procedure determined the relative activity of the materials. These screening results for model nanoparticle systems were related to traditional electrochemical experiments and showed a strong correlation. Building on that initial study, the BPE platform for screening ORR electrocatalyst candidates was improved so that more materials could be evaluated simultaneously by increasing the density of electrodes in the array, controlled compositional variations were prepared with the implementation of piezodispensing, and a different reporter, Cr, replaced Ag at the BPE anodes which reduced the risk of contamination and improved reliability of screening experiments. Further studies into the versatility of the screening platform have been carried out using non-noble metal systems for the hydrogen evolution reaction (HER), which has a long history of interest for electrochemists. A single conductive electrode material can be made to act as an array of electrodes by confining it at the intersection of two orthogonal microfluidic channels. By manipulating the direction and magnitude of the electric field in the device, faradaic reactions can be selectively localized on the BPE. An approach for optically tracking individual, insulating microparticles interacting with an active UME has been achieved. This approach brings new insight and understanding of single particle electrochemical studies. Finally, a method for incorporating microwires and mesh electrodes into paper-based electroanalytical devices is reported. This has many advantages over traditional screen-printed carbon electrodes that are traditionally used in paper-based devices.Item Charge-transfer complexes of photochemically interesting organic systems(Texas Tech University, 1972-05) Park, Su MoonNot availableItem A comparison of the effects of mobile device display size and orientation, and text segmentation on learning, cognitive load, and user perception in a higher education chemistry course(2015-05) Karam, Angela Marie; Resta, Paul E.; Liu, Min; Hughes, Joan E.; Riegle-Crumb, Catherine; Matthew, EastinThis study aimed to understand the relationship between mobile device screen display size (laptops and smartphones) and text segmentation (continuous text, medium text segments, and small text segments) on learning outcomes, cognitive load, and user perception. This quantitative study occurred during the spring semester of 2015. Seven hundred and seventy-one chemistry students from a higher education university completed one of nine treatments in this 3x3 research design. Data collection took place over four class periods. The study revealed that learning outcomes were not affected by the mobile screen display size or orientation, nor was working memory. However, user perception was affected by the screen display size of the device, and results indicated that participants in the sample felt laptop screens were more acceptable for accessing the digital chemistry text than smartphone screens by a small margin. The study also found that neither learning outcomes, nor working memory was affected by the text segmentation viewed. Though user perception was generally not affected by text segmentation, the study found that for perceived ease of use, participants felt medium text segments were easier to learn from than either continuous or small test segments by a small margin. No interaction affects were found between mobile devices and text segmentation. These findings challenge the findings of some earlier studies that laptops may be better for learning than smartphones because of screen size, landscape orientation is better for learning than portrait orientation in small screen mobile devices, and meaningful text segments may be better for learning than non-meaningful, non-segmented, or overly segmented text. The results of this study suggest that customizing the design to the smartphone screen (as opposed to a one-size-fits-all approach) improves learning from smartphones, making them equal to learning from laptops in terms of learning outcomes and cognitive load, and in some cases, user perspective.Item Conformational analysis of dioxanes and dioxolanes(Texas Tech University, 1972-12) Moore, AnaNot availableItem Cyanoethylation of alkylpyridine methiodides(Texas Tech University, 1964-08) Flores, Robert JosephNot availableItem Design, synthesis, and calorimetric studies on protein-ligand interactions : apolar surface area, conformational constraints, and cation-[pi] interactions(2013-05) Myslinski, James Michael; Martin, Stephen F.Because bimolecular interactions in water are poorly understood, three tactics commonly used to improve binding affinity in ligand design were investigated: (1) increasing apolar surface area, (2) introducing a conformational constraint, and (3) targeting a cation-[pi] interaction. Thermodynamic parameters of binding ligands to the Grb2 SH2 domain were determined by isothermal titration calorimetry (ITC), and structural data was obtained by X-ray crystallography. The apolar surface area of the pTyr+1 residue in Ac-pTyr-Acnc-Asn-NH₂ was varied by incrementally increasing the size of the cyclic Acnc residue from a 3-membered to a 7-membered ring. Increasing apolar surface area resulted in an increase in Ka due to a more favorable [delta]H⁰ that was dominated a less favorable [delta]S⁰. Structural analyses showed that all ligands bound in a similar mode, so differences in binding thermodynamics were attributed to the pTyr+1 residue. The thermodynamics of binding tripeptides wherein pTyr+1 was an n-alkyl group were studied. Ka increased when Ala was mutated to Abu, but additional methylene groups had no effect on Ka due to strong entropy-enthalpy compensation. While [delta]H⁰ was weakly correlated with buried surface area, there was no change in [delta]H⁰ between one methylene and two methylene groups, presumably because an enthalpic penalty is associated with a gauche interaction between C-[beta] and C-[gamma] of the Xaa side chain that was noted in the crystal structure. An olefin was installed in an attempt to alleviate the energetic penalty incurred from the gauche interaction, but the introduction of the constraint resulted in equipotent ligands. A putative cation-[pi] interaction between Arg67 and various aromatic groups was probed by varying the [pi]-donating capability of groups attached to a tripeptide scaffold. Although crystal structures demonstrated that three of the aryl groups were close enough to Arg67 to form a cation-[pi] interaction, only a modest increase in Ka was observed relative to analogues having only an N-acetyl group. Furthermore, a simple cyclohexyl group in place of aryl groups resulted in ligands that were equipotent with indolyl- and phenyl- derived analogues, so any cation-[pi] interaction is not significant.Item Effects of using presentation formats that accommodate the learner's multiple intelligences on the learning of freshman college chemistry concepts(2004-12) Brown Wright, Gloria Aileen; Lagowski, J. J.Howard Gardner's Theory of Multiple Intelligences identifies linguistic, spatial and logical-mathematical intelligences as necessary for learning in the physical sciences. He has identified nine intelligences which all persons possess to varying degrees, and says that learning is most effective when learners receive information in formats that correspond to their intelligence strengths. This research investigated the importance of the multiple intelligences of students in first-year college chemistry to the learning of chemistry concepts. At three pre-selected intervals during the first-semester course each participant received a tutorial on a chemistry topic, each time in a format corresponding to a different one of the three intelligences, just before the concept was introduced by the class lecturer. At the end of the experiment all subjects had experienced each of the three topics once and each format once, after which they were administered a validated instrument to measure their relative strengths in these three intelligences. The difference between a pre- and post-tutorial quiz administered on each occasion was used as a measure of learning. Most subjects were found to have similar strengths in the three intelligences and to benefit from the tutorials regardless of format. Where a difference in the extent of benefit occurred the difference was related to the chemistry concept. Data which indicate that students' preferences support these findings are also included and recommendations for extending this research to other intelligences are made.Item Electric moments from extrapolated mixed solvent data: a thesis in chemistry(Texas Tech University, 1955-05) Stembridge, Charles HenryNot available