Tesis sobre el tema "Chemisty (Theses)"

Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The need to analyse and detect volatile organic compounds (VOCs) at trace levels has led to the development of specialized sample preparation techniques. The requirement for trace analysis of VOCs stems from the negative effects they have on the environmental and human health. Methods for the analysis of non-polar VOCs commonly found as trace contaminants in water and analysis of more polar oxygenated compounds commonly found in zero-VOC water-based paints were developed. Solid phase micro extraction (SPME) was employed and extraction of the majority of the target analytes could be achieved at levels below 0.3 μg.l-1. In an attempt to further improve the detection of these two target analyte groups, novel materials based on poly(dimethyl siloxane) (PDMS) were investigated as possible extraction phases for VOCs, with the focus specifically on the analysis of the polar analytes in paint. Conventional free radical polymerization was used to synthesize poly(methyl methacrylate-graft-poly(dimethyl siloxane) (PMMA-g-PDMS), poly(methacrylic acid)-graft-poly(dimethyl siloxane) (PMAA-g-PDMS), polystyrene-graftpoly( dimethyl siloxane) (PSty-g-PDMS) and poly(butyl acrylate)-graft–poly(dimethyl siloxane) (PBA-g-PDMS). These polymers have a copolymer functionality which presents a series of different polarities. The MMA-g-PDMS and MAA-g-PDMS as well as the homopolymers were electrospun into nanofibers. The low glass transition temperature and molecular weight of the PBAg- PDMS meant that this polymer could not be electrospun. Scanning electron microscopy (SEM) was used to study the fiber morphology of the electrospun fibers and the non-beaded fibers were further investigated. Polyacrylonitrile-graft-poly(dimethyl siloxane) (PAN-g-PDMS) previously synthesized and electrospun by another member of the group were also investigated for use as possible extraction material in volatile analysis. The thermal stability of the nanofibers at 200°C was studied using thermal gravimetric analysis (TGA). This property is important since after the target analytes are extracted using the nanofibers, elevated temperatures are used to thermally desorp the volatile analytes from the extraction materials prior to GC analysis. The PAN-g-PDMS, MMA-g-PDMS and PMMA showed no significant weight loss during thermal evaluation, however, it was observed that the PMMA and PMMA-g-PDMS nanofibers looses their nanostructure and that the PAN-g-PDMS nanofibers changes colour from white to yellow to rust brown. The polymers based on MAA showed weight losses of more than 10% after one hour of exposure to the elevated temperatures, but the nanostructure remained intact. The PAN-g-PDMS, PMAA-g-PDMS and PMAA nanofibers were evaluated as possible extraction materials for VOC analysis. The nanofibers were evaluated using a similar approach to that of stir bar sorptive extraction (SBSE). Headspace sorptive extraction (HSSE) using a commercially available PDMS stir bar and the novel materials were used to evaluate the extraction efficiency of the different materials. The optimized extraction method developed using SPME were employed for the extraction using the nanofibers and PDMS stir bar. It was noted that the nanofibers lose their extraction capabilities during the first extraction/desorption cycle possibly due to thermal degradation therefore each of the materials can only be used in a single extraction. The majority of the non-polar analytes were extracted using the nanofibers at levels of 500 μg.l-1, however it was noted that the commercially available SPME extraction materials and the PDMS stir bar had superior extraction efficiencies for the specific target analytes. In the evaluation of the nanofibers for extraction of the more polar oxygenated analytes it was noted that 2-Ethylhexylacrylate was the only analyte to be extracted by all of the materials. The PAN-g-PDMS extracted three of the four analytes at levels of 100 μg.l-1. At lower analyte concentrations of 10 μg.l-1 only two of the four acrylate compounds were detected using the PAN-g-PDMS nanofibers. Ethyl acrylate was not extracted by any of the novel materials, whereas in SPME using the CAR/PDMS fiber, the LOD was determined to be below 1 μg.l-1. Although these materials were not superior to the commercially available phases, this is only the case for the specific target analytes analyzed.
AFRIKAANSE OPSOMMING: Die behoefte vir die analiese van vlugtige organiese verbindings (VOS) op spoorvlak, het gelei tot die ontwikkeling van gespesialiseerde monster voorbereidingstegnieke. Die vereiste vir die spoor analiese van die VOS het ontstaan uit die negatiewe uitwerking wat hierdie stowwe het op die omgewing en menslike gesondheid. Metodes vir die analiese van nie-polêre VOS wat algemeen voorkom as spoorkontaminante in water en polêre suurstofryke verbindings wat algemeen voorkom in nul-VOS water-gebaseerde verf was ontwikkel. Soliede fase mikro-ekstraksie (SFME) was gebruik, en die ekstraksie van die meerderheid van die teikenstowwe kon gedoen word op vlakke laer as 0,3 μg.l-1. In 'n poging om die opsporing van hierdie twee teiken analietgroepe verder te verbeter, is nuwe materiale gebaseer op polidimetielsiloksaan (PDMS), ondersoek as moontlik ekstraksiefases vir VOS, met die fokus spesifiek op die analiese van die polêre stowwe in verf. ’n Konvensionele vrye radikaal polimerisasieproses was gebruik om poli (metiel- metakrilaat)-entpoli( dimetielsiloksaan) (PMMA-g-PDMS), poli(metakrilaatsuur)-ent–poli (dimetielsiloksaan) (PMAA-g-PDMS), polistireen-ent-poli(dimetielsiloksaan) (PSty-g-PDMS) en poli(butielakrilaat)- ent-poli(dimetielsiloksaan) (PBA-g-PDMS) te sintetiseer. Hierdie ko-polimere het 'n kopolimeer funksionaliteit wat 'n reeks van verskillende polariteite bied. Die MMA-g-PDMS en MAA-g-PDMS sowel as die homopolimere was ge-elektrospin in orde om nanovesels te vorm. Die lae glasoorgangstemperatuur en molekulêre gewig van die PBA-g-PDMS het beteken dat hierdie polimeer nie elektrospin kon word nie. Skandeerelektronmikroskopie (SEM) was gebruik om die veselmorfologie van die ge-elektrospinde vesels te bestudeer en die nanovesels wat ’n eweredige oppervlak gehad het, was verder ondersoek. Poliakrilonitriel-ent-poli(dimetielsiloksaan) (PAN-g- PDMS) wat voorheen gesintetiseer en ge-elektrospin was deur 'n ander lid van die groep is ook ondersoek vir gebruik as moontlik ekstraksiemateriaal vir die analiese van vlugtige stowwe. Die termiese stabiliteit van die nanovesels was by 200°C bestudeer met behulp van ‘n termiese gravimetriese analiese (TGA) instrument. Hierdie eienskap is belangrik, aangesien die teikenstowwe by hoë temperature van die nanovesels gedesorbeer word voor die GC-analiese. Die PAN-g-PDMS, MMA-g-PDMS en PMMA het geen beduidende gewigsverlies tydens termiese evaluering gehad nie, alhoewel dit egter waargeneem was dat die PMMA en PMMA-g-PDMS nanovesels hulle nanostruktuur verloor en dat die PAN-g-PDMS nanovesels se kleur verander van wit na geel na roesbruin gedurende die termiese analiese. Die polimere wat gebaseer was op MAA het ’n gewigs-verlies van meer as 10% getoon na 'n uur van blootstelling aan die verhoogde temperature, maar die nanostruktuur het ongeskonde gebly. Die PAN-g-PDMS, PMAA-g-PDMS en PMAA nanovesels was geëvalueer as moontlike ekstraksiemateriale vir VOS-analiese. Die nanovesels was geëvalueer met 'n soortgelyke benadering tot dié van “stir bar“ sorpsie ekstraksie (SBSE). Bo-ruimte sorpsie ekstrasie is gebruik om die ekstraksie-doeltreffendheid van die verskillende materiale (kommersiële PDMS en nanovesels) te evalueer. Die geoptimaliseerde ekstraksiemetode ontwikkel in SFME was gebruik vir die ekstraksie van die VOS met die nanovesels en die PDMS “stir bar“. Dit was waargeneem dat die nanovesels hul ekstraksievermoë verloor tydens die eerste ekstraksie/desorpsie siklus, moontlik as gevolg van termiese degradasie dus, kon die materiale slegs ‘n enkele maal gebruik word vir die ekstraksie. Die meerderheid van die nie-polêre stowwe was ge-ëkstraeer deur gebruik te maak van die nanovesels op vlakke van 500 μg.l -1, maar die kommersieel beskikbare SFME ekstraksie materiale en die PDMS “stir bar“ se ekstraksie-doeltreffendheid vir die spesifieke stowwe was beter. In die evaluering van die nanovesels vir die ekstraksie van die meer polêre suurstofryke stowwe was daar waargeneem dat 2- etielheksielakrilaat die enigste analiet was wat ge-ëkstraeer was deur al die materiale. Die PAN-g- PDMS kon drie van die vier polêre stowwe op vlakke van 100 μg.l-1 opspoor. By laer analietkonsentrasies van 10 μg.l-1 kon slegs twee van die vier akrilaat verbindings opgespoor word deur gebruik te maak van hierdie nanovesels. Etielakrilaat was nie ge-ëkstraeer deur enige van die nuwe materiale nie, terwyl in SFME met die gebruik van die CAR/ PDMS vesel, die analiet op vlakke onder 1 μg.l-1 opgespoor kon word. Alhoewel hierdie nuwe materiale nie beter is as die kommersieel beskikbare ekstraksiemateriale nie is dit net die geval vir die spesifieke teiken analietgroepe wat ondersoek was in hierdie studie.

Aquí encontrará un resumen ampliado de las tesis de licenciatura y maestría presentadas en 2010 por los alumnos de investigación de la sección Química  de la PUCP.
Aquí encontrará un resumen ampliado de las tesis de licenciatura y maestría presentadas en 2010 por los alumnos de investigación de la sección Química  de la PUCP.

This thesis covers the use of chemistry in the automotive industry with emphasis on environmental compliance via chemical reporting by database and internal Energy Dispersive X-ray Fluorescence (XRF) screening, third party laboratory material testing, and the future of the chemist in the United States (U.S.) automotive industry. The third party testing was performed at Western Kentucky University (WKU) via the Materials Characterization Center (MCC), Institute for Combustion Science and Environmental Technology (ICSET) Thermodynamics Laboratory, and using the Scanning Electron Microscope/Energy Dispersive X-ray Spectrometer (SEM/EDX) managed by the WKU Biotechnology Center. Furthermore, the tests conducted were used to investigate material defects, provide solid third party quantitative results to support our XRF screenings to ensure environmental compliance, and determine cost effective material replacements. The company for which the testing was performed and information obtained is involved with the production of electronics for many of the major automotive companies throughout the world. The company specializes in the production of wiring harnesses, electrical control units (ECU), boxes (junction, fuse, relay, etc), and electrical components. These four areas control everything from the vehicle's lights, CD/DVD player, and heater to windows, locks, and navigation system. The automotive industry is extremely competitive; therefore, each company must continually change and improve in order to survive. New materials are constantly required to meet the reduced costs implemented by the customer, as well as, improve the function and quality of the components, while maintaining compliance with global environmental standards.

Western Kentucky University (WKU) offered a course entitled Biochemistry for the Health Sciences in the spring semester of 2007. The course was taught in Interactive Television (ITV) format, and was the first time a class had been taught in the format enabling two-way communication by the Chemistry Department. One section was present in an ITV broadcast classroom on the main campus in Bowling Green, Kentucky. Another section received the broadcast on the campus of Western Kentucky University-Owensboro (WKU-O), at Owensboro Community and Technical College (OCTC), located in Owensboro, Kentucky. The purpose of this thesis is to evaluate the delivery of the chemistry class and to ascertain if ITV is a suitable format for chemistry classes. Professor Larry Byrd taught the class in person to twenty-nine students in Bowling Green. David Martin, the author of this thesis, attended the class at WKU-0 along with one student, who was required to take the class for her Health Sciences major. The thesis addresses the technical aspects of an ITV class, the logistical challenges faced at both locations, the subject matter covered, and the reactions of students. A survey was administered to the Bowling Green class and the Owensboro student was interviewed. Suggestions for improvements were made for future classes. The conclusion is that ITV can certainly be used successfully for the delivery of chemistry classes. The student in Owensboro received an "A" for the semester. This result compared to 50% "A's", 32 % "B's", 9% "C's", and 9% "D's" and "W's" for the total class. The most needed improvement for the class is the inclusion of demonstrations of laboratory experiments on video. The technical and logistical challenges encountered can be overcome with more experience on the part of the professor and improvements in the courier transportation system. This particular class is scheduled to be offered via ITV in the fall 2007 semester and will be broadcast to multiple remote locations. This limited study of an ITV chemistry class shows that the delivery method is appropriate and reasonable. To broaden the statistical base for comparison of ITV classes to traditional classes, another series of experiments should be performed. A proposal for a study between a traditional class, an ITV main campus class, an ITV remote class, and a web-based class is included. This study is designed to compare student performance over a range of delivery methods for the same course.

Includes bibliographical references. Details research carried out into the nonlinear optical properties of metal alkynyls, chiefly organoruthenium complexes, showing that these complexes can be designed to have very large NLO coefficients. Also demonstrates the utility of spectroscopic, electrochemical and copmutational aids as predictive tools for NLO materials. Also examines cluster synthesis, reactivity and physical properties using ruthenium clusters and hard-donor ligands, affording a series of cluster complrxes that provide structural models for industrially-important hydrotreating intermediates.

Resumen de las tesis de licenciatura y maestría presentadas hasta septiembre de 2016 en la Sección Química de la PUCP.
Master and "licenciatura" thesis defended at the chemistry section in 2016 (until september, also included)

Resumen de las tesis de licenciatura y maestría presentadas de octubre 2017 a diciembre 2017 en la Sección Química de la PUCP
Master and "licenciatura" thesis defended at the chemistry section in from October 2016 to December 2017

Radical ions are reactive intermediates that are both radicals and ions (either a radical cation or a radical anion). The intrinsic properties of radical ions are not yet well -characterized. Such knowledge is mechanistically important to the organic chemist. The specific question that motivates this research is as follows: is it possible to controllably express free radical processes in a radical ion independent of ionic chemistry (and vice versa) and, if so, what factors dictate which type of chemistry is expressed? Our investigation focused on the chemistry of radical anions of dicyanoalkanes that are formed upon metal reduction. Factors influencing this chemistry such as solvent effects were also studied. This study represents a small segment of a larger study of five functional group classes of molecules, that will ultimately involve a description of the chemistry of radical anions. The goal of the overall project is to attain a generalized view of the chemistry of radical anions of bifunctional organic molecules. The results obtained suggest that free-radical processes (cyclization and polymerization) can be expressed within radical anions. Furthermore, our results show that free -radical polymerization as opposed to cyclization is the dominant mode of reaction. Such an observation has not been established before for radical anion systems. The requisite background information regarding what is known about these reactive intermediates to date, and rationalization as to why more information is needed through this, and the work of other scientists, is laid out in the following introduction.

The corrosion of infrastructure imposes a significant monetary cost, and at times human cost, upon society. Methods to improve corrosion resistance of materials are described herein which utilize the reversibility of the Diels-Alder reaction to impart thermal responsiveness upon materials. Such stimuli responsiveness can potentially play a role in self healing properties which lead to reduced cracking and thus increased corrosion protection. Reversible Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates. Hydrophobic dieneophiles were prepared and attached to glass slides and capillaries to yield a nonwetting surface. Thermal treatment of the surfaces cleaved the Diels-Alder linkage, and resulted in the fabrication of a hydrophilic surface. Preliminary analysis utilized contact angle (CA) measurements to monitor the change in surface energy, and observed a hydrophilic state (CA - 70±3°) before attachment of the dieneophile to a hydrophobic state (CA - 101±9°) followed by regeneration of the hydrophilic state (CA - 70±6°) upon cleavage of the Diels-Alder linkage. The treatments were then applied to glass capillaries, with effective treatment confirmed by fluid column measurements. Patterned treatments were also demonstrated to provide effective fluid flow gating. Reversible Diels-Alder linkages were incorporated into polymer thermoset binding resins in order to provide a means by which a crosslinked thermoset could undergo stimuli responsive reversible crosslinking. The binder systems which were utilized included two types of amine curing agents, polydimethylsiloxane (PDMS) and Jeffamine® polyetheramines (PEA), and two types of epoxy resins, EPON resin based on diglycidyl ether of Bisphenol-A and epoxidized soybean oil. Various dienes and dienophiles were employed to functionalize the selected binder systems and were met with various degrees of success. The synthetic technique which proved to be the most promising was the Diels-Alder modification of the epoxidized soybean oil.

The strong affinity of carbon nanotubes with environmental contaminants has raised serious concern that carbon nanotubes may function as a facilitator to transport environmental pollutants from a location to another through adsorption, therefore leading to unexpected contamination and toxicity incurred by the environmental pollutants and pose new risks in unexpected places. However, this concern is not realized unless the contaminants are desorbed from carbon nanotubes. Upon contact with different environmental conditions, the desorption of environmental pollutants from CNTs varies greatly. Even though numerous investigations have been conducted to investigate the adsorption of environmental pollutants on carbon nanotubes, few studies have been done to investigate the mechanisms of desorption process. The main focus of our research is to study the influence of solution chemistry (e.g. pH, ionic strength and Natural Organic Matter) on the desorption of preloaded 1,3,5-trichlorobenzene (1,3,5-TCB) from multi-walled carbon nanotubes (MWCNTs). Due to the manipulative surface property and the existence of a variety of functionalized carbon nanotubes, the effect of surface properties of carbon nanotubes on the desorption process was also investigated. The investigation showed that both the solution chemistry and surface chemistry has substantial impact on the adsorption of 1,3,5-TCB on carbon Nanotubes. Aqueous solution chemistry of ionic strength and NOM showed significant difference in desorption with the change in surface chemistry of MWNTs. Functionalized MWNTs with oxygen containing functional group shows less affinity toward the desorption process than the non-functionalized one. pH showed not much significant difference for desorption between the no-functionalized and functionalized MWNTs but proved notable difference in desorption between the acidic and basic state.

This research studies the chemical nature of zirconia and the complex surface chemistry of zirconia in order to better comprehend its behavior under chromatographic conditions. This research shows how the physical and chemical properties of zirconia depend strongly on the thermal treatment during synthesis. The morphology of the samples was also studied. The absorption capability of Adenosine Triphosphate (ATP) on zirconia was also monitored and spectrally characterized. The results of this research showed how the properties of zirconia vary with thermal treatment. It was observed that the zirconia prepared at a higher temperature had lower surface area, lower pore size and pore volume as compared to the zirconia prepared at a lower temperature. The morphology studies showed the porosity of the zirconia. The results from the absorption experiments showed that zirconia prepared at a higher temperature absorbed more ATP than the zirconia prepared at a lower temperature. Significant changes were also observed on the pellets of zirconia pre and post absorption experiments. I hope that this research sheds more light on the complex properties of zirconia’s surface chemistry and the results of this study could better help in the application and use of zirconia in chromatography to separate proteins.

In many secondary education chemistry classrooms, teachers have a difficult time introducing chemistry topics in a way that will be interesting to the high school student. The development of a materials and environmental chemistry teacher's manual will help teachers introduce a variety of selected topics in an interesting fashion to the students. This manual focuses on the subjects covered for freshman and sophomore level students. The manual uses five separate experiments to introduce topics such as the electromagnetic spectrum and solubility. The five experiments include a test on tennis shoe stiffness and energy dissipation ability, pesticides in water, grease in vent hoods, concentration of salicin in willow, and a paint adhering test on a vehicle bumper. The manual introduces several chemistry concepts by relating the subject to projects that the students can understand because they are useful to society and the environment. By presenting the material in this manner, students should be able to focus on the specific concepts longer, thus understanding the concepts better. Some of the lessons cover a topic that is required by the American Chemical Society (ACS) for postsecondary education materials chemistry classes. The inclusion of these topics will increase the knowledge of future chemistry students in an area that will be required at multiple postsecondary education institutions. Each experiment topic includes background information, teacher information, lesson objectives, ACS topic and/or experimental subject covered, lesson, definitions, supplements, transparencies, and a worksheet.

The purpose of this research has been to investigate the mechanisms and develop techniques for electron beam induced chemistry. Applications for electron beam chemistry include repair and fabrication of lithographic masks, integrated circuit repair and rewiring, nanofabrication of functional nanoscale tools and scanned probe microscopy tips and damage free transmission electron microscope sample preparation. The use of hydrocarbon contamination as a precursor has been investigated and complex three dimensional nanostructures have been successfully fabricated. Accelerating voltage and scan speed can be used to control the morphology of the deposits. The development and implementation of an internal precursor reservoir and introduction device that is transferable to various scanning electron microscope and focused ion beam instruments has been performed. The effects of beam and scan parameters on the deposition efficiency of carbon structures utilizing a phenanthrene precursor has been investigated. Deposition efficiency is maximized for low beam current, large scan areas exposed for short times using the experimental conditions in this work. However, the use of a focused ion beam provides a significantly higher deposition efficiency (over 45 times) than that of an electron beam.

Aquí encontrará el resumen de las tesis de licenciatura y maestría presentadas en 2013 por los alumnos de investigación de la sección Química de la PUCP.
In this section the reader will find the abstract of the Master and Licenciate thesis defended at the PUCP´s Chemistry Section in 2013.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1998.
Includes bibliographical references.
by Rebecca J. Carazza.
Pt. A. Paeoniflorin -- pt. B. (+)- Taxusin.
Ph.D.

Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, Discipline of Chemistry, 2005?
"July 2004" Includes copies of publications by the author as appendix. Includes bibliographical references.

AN ABSTRACT OF THE THESIS OF Nicole K. Jensen, for the Masters of Science degree in Forestry, presented on April 3, 2012, at Southern Illinois University Carbondale. TITLE: TREE-RING CHEMISTRY AND GROWTH RESPONSE TO EXPERIMENTAL WATERSHED ACIDIFICATION MAJOR PROFESSOR: Dr. Eric Holzmueller Forest ecosystems in the eastern United States are threatened by acid deposition rates that have increased dramatically since industrialization. We utilized two watersheds at the Fernow Experimental Forest in West Virginia to examine long-term effects of acidification on ecological processes. One watershed has been treated with ammonium sulfate (approximately twice the ambient deposition rate) since 1989 to simulate acid deposition while the other served as a control. Prior to treatment both watersheds were similar in age and species composition. Ten dominant overstory Prunus serotina and Liriodendron tulipifiera trees were selected and cored from each watershed to measure bolewood concentrations of elements essential for growth over time. In addition, changes in tree species basal area were analyzed utilizing 50 long-term growth plots established in 1990. Results of this experiment show lower calcium and magnesium concentration and increased acidic cation concentration in the treated watershed for both species indicating a negative treatment effect. These results were similar to that of a previous study conducted at the Fernow with periods of significant differences in cation concentrations between the treated and control watershed. Growth response, measured through relative growth rates of cored trees and changes in basal area from growth plots, was not as conclusive, but it did appear that treatment may be having a negative affect for both species during the last measurement of the growth plots. These results indicate a need for further research to understand the impact of long-term acidification so that sustainable forest management practices in areas affected by acid deposition may be developed.

Prior research endorsed two theories of misattribution of interpersonal attraction. Both the two-component theory and the excitation transfer theory demonstrate misattribution and, in combination, enhance the probability of misattribution. However, which theory provides the primary source of misattribution has not been distinguished. The present study asked 60 undergraduate males to rate their interpersonal attraction toward a female in a video recording engaging in self disclosure. A manipulation of different levels of environmental saliency and physiological arousal was used to determine which condition or combination of conditions is most likely to elicit misattribution of interpersonal attraction. An analysis of variance followed by an analysis of covariance was performed on the interpersonal attraction ratings. The covariate of base pulse rate was used to control for individual difference of arousal. The results did not indicate a statistical difference of misattribution under any of the manipulated conditions. The expansion of the arousal conditions is discussed as a prerequisite of misattribution effects. Further research is recommended in the areas of female misattribution of interpersonal attraction and individual cognitive recovery levels.

Bibliography: leaves 151-166. This thesis describes the development of two novel and complementary analytical approaches for assaying cyanoalanine non-protein amino acids. These assays are used to determine the distribution of these compounds both within and between plants and to identify accessions of common vetch which contain low levels of the cyanoalanine non-protein amino acids in germplasm collections. These analytical tools are used to correlate toxicity observed in animal feeding experiments with the cyanoalanine content. This thesis covers also the first report of the use of diffuse reflectance using dispersive infrared spectrometry for the "in situ" quantification of specific organic components from plant tissue as well as the first use of micellar electrokinetic chromatography for the quantitative analysis of 9-fluorenylmethyl chloroformate (FMOC) derivatised and non-derivatised components of extracts from plant material.

Estuaries are dynamic environments that are strongly affected by natural variability, as well as direct and indirect anthropogenic impacts. A better understanding of the drivers of carbon fluxes and biogeochemical variability in estuarine systems is needed, particularly with the increasing threat of ocean acidification. Morro Bay in Central California is a small nationally protected estuary, with seasonally low freshwater inputs. Since 2007, the bay has experienced a significant loss of native seagrass, Zostera marina, which is an important component of the marine ecosystem. Because seagrass photosynthesis decreases carbon dioxide and increases oxygen in the water column, the loss of seagrass has the potential to substantially change short-term carbonate chemistry and long-term carbon fluxes of an estuary. The spatial variability of carbonate chemistry was measured in Morro Bay using ship-board surveys during the low-inflow summer season and measured the temporal variability by collecting samples close to the shore from July to November. Discrete samples show an increase in total alkalinity and dissolved inorganic carbon in the mid and back bay regions, historically dominated by seagrass. Slightly lower total alkalinity and dissolved inorganic carbon were observed in the Fall season compared to the low-inflow Summer season. Analysis of the relative modification of alkalinity and dissolved inorganic carbon, paired with salinity and temperature data, contributes to an understanding of the drivers of the observed carbonate variability. This understanding may provide clues to the causes and effects of observed changes to the bay with seagrass loss. More broadly, it will inform the vulnerability of other low-inflow estuaries to future acidification and highlight the role seagrasses play in mitigating local acidification.

A field experiment was conducted in the Rockpile appellation of Sonoma County during 2007 and 2008. The experimental design was a randomized complete block with five replicates. Zinfandel vines were subjected to three levels of cluster thinning during the lag phase of berry growth: vines were thinned to 2 clusters per shoot with shoulders retained if present (2CS), 1 cluster per shoot with shoulders retained if present (1CS), or 2 clusters per shoot with shoulders removed if present (2CNS). Cluster thinning Zinfandel grapevines during lag phase led to reductions in yield and crop load and increased °Brix of the fruit. In both years, wines that were made from vines with the lowest crop load had consistently higher amounts of small and large polymeric pigments, tannins and total iron-reactive phenolics. Cluster thinning vines to 2CNS at lag phase consistently decreased the number of berries per cluster and cluster weight. Thinning vines to 1CS resulted in fewer clusters per vine in 2008. Botrytis bunch rot tends to develop between the shoulder or wing and the main cluster in certain varieties. Shoulder removal in areas with a high risk of Botrytis should conclusively determine if this thinning method helps to decrease disease incidence. Additional research is also recommended with other varieties to assess possible differences between shoulder thinning and removing entire clusters on berry composition, yield, subsequent wine composition and crop load.

Thesis (MSc)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Cancer is the leading cause of death on the planet, killing an estimated 8.2 million people in the year of 2012.The disease is associated with two families of genes, namely oncogenes and tumour suppressor genes. The hallmarks of cancer pathogenesis include gene amplification, point mutations or chromosomal rearrangements within these genes. Kinases are responsible for the reversible phosphorylation of proteins, which plays a significant and extensive role in cellular signal transduction. Aberrant kinase activity provokes overexpression, mutations and chromosomal translocation and results in the onset of onco- and tumorogenesis, ultimately leading to cancer. Inactivation of this class of enzyme is thus critical as it would result in the suppression of these unwanted activities. For this, researchers have developed kinase inhibitors, specifically targeting these proteins and thus inhibiting signal transduction pathways and tumour growth. This has resulted in great successes, particularly in the case of the commercial inhibitor, imatinib. However, resistance to approved therapeutic agents through mutations has resulted in the search for more potent and selective inhibitors to overcome these obstacles. This project involved the synthesis of bioactive heterocycles linked to 1,2,3-triazoles using either a C-C or C-N bond forming strategy. The synthetic methodology followed included the use of Sonogashira coupling reactions between3-bromoquinoline, 7-chloro-4-iodoquinoline, 4-bromoisoquinolineand5-bromoisoquinolineand trimethylsilylacetylene (TMSA), followed by deprotection of the TMS group to yield heterocycles bearing terminal alkynes. The synthesis of both benzyl azide and 2-(azidomethyl)pyridine as azide fragments, allowed for subsequent coupling of the synthesized azide and alkyne fragments through copper-mediated click chemistry, affording a library of 1,4-substituted 1,2,3-triazole based reversible kinase inhibitors. Synthesis of a second library of o-, m- and p-substituted nitro benzyl azides, allowed for both copper- and ruthenium-mediated click reactions, between the alkynes and nitro benzyl azides synthesized, to yield 1,4- and 1,5-substituted 1,2,3-triazoles, respectively. Finally, reduction of the incorporated o-, m- and p- substituted nitro group, and acylation of the resultant amine with acryloyl chloride, resulted in the incorporation of the important Michael acceptor moiety required for irreversible inhibition. This afforded a library of both reversible and potential irreversible triazole-based kinase inhibitors through efficient copper- and ruthenium-mediated click chemistry. Biological screening and activity assays against the wildtype, and two mutated forms of the EGFR kinase, were undertaken with these synthesized compounds.A number of synthesized inhibitors showed good selectivity for the mutated forms of the EGFR kinase only.The most potent inhibitor N-{2-{[4-(isoquinolin-4-yl)-1H-1,2,3-triazol-1-yl]methyl}phenyl}acrylamide,displayed efficacy in the low μM range - comparable to that of the FDA approved drug, gefitinib. The synthetic methodology derived in this project could be applied to the use of biological space probes with further investigatory research. Furthermore, from the biological screening results obtained, and the selectivity profile shown by these inhibitors, the synthesis of a second generation library of compounds is an additional research possibility.
AFRIKAANSE OPSOMMING: Kanker is die hoof oorsaak van sterftes ter wêreld, wat verantwoordelik is vir die dood van ongeveer 8.2 miljoen mense in die jaar 2012. Die siekte word geassosieer met twee geenfamilies, naamlik onkogene en gewasonderdrukkingsgene. Die kenmerke van kanker pathiogene behels geenversterking, puntmutasies of chromosomale herrangskikking binne in die gene. Kinase is verantwoordelik vir die omkeerbare fosforilering van proteine wat 'n uiters belangrike rol in sellulere sein transduksie speel. Abnormale kinase aktiwiteit lei tot ooruitdrukking, mutasies en chromosomale translokasie wat tot die ontwikkeling van onko- en gewasgroei en wat eindelik tot kanker lei. Deaktivering van die klas van ensieme is dus krities want dit sal die ongewenste abnormale aktiwiteite onderdruk. As gevolg van die bogenoemde, het navorsers kinase inhibeerders ontwikkel wat die spesifieke protein teiken en hiermee die sein transduksie roete asook gewas groei inhibeer. Hiermee het die sukses van inhibeerders veral die kommersiele inhibeerder, imatinib, grootliks toegeneem. Oor die afgelope jare het die belangstelling in die ontwikkeling van meer selektiewe en kragtige inhibeerders toegeneem as gevolg van die weerstand wat goedgekeurde terapeutiese middels opbou. In hierdie projek is daar gebruik gemaak van 'n C-C of C-N bindingsvorming strategie om bioaktiewe heterosikliese molekules te sintetiseer wat gekoppel is aan 1,2,3-triasool funksionele groepe. Die sintetiese metode maak gebruik van Sonogashira reaksies vir die 3-bromo-kwinolien, 7-chloro-4-iodokwinolien, 4-bromoisokwinolien en 5-bromoisokwinolien met trimetielsilielasetileen (TMSA), gevolg met die ontskerming van die TMS-groep om die terminale alkyn op die heterosiklusse te ontbloot. Die asied fragmente, bensiel asied en 2-(asidometiel)piridien, was toe gesintetiseer om met die gevormde heterosiklus alkyne 'n koper ondersteunende kliek chemie te ondergaan. 'n Reeks van 1,4-digesubstitueerde 1,2,3-triasool gebaseerde omkeerbare kinase inhibitore is toe gevorm. 'n Tweede reeks met o-, m-, en p- gesubtitueerde nitro bensiel asiede was gesintetiseer om 1,4- en 1,5- digesubtitueerde 1,2,3-triasole te sintetiseer met behulp van koper- en ruthenium ondersteunende kliek chemie. Laastens was die o-, m-, en p- nitro groepe gereduseer om 'n primêre amien te vorm. Die gevormende amien het 'n asileringsreaksie met akriloïel chloried ondergaan om die kern, die Michael akseptor, te inkorporeer. Die Michael akseptor word benodig om 'n onomkeerbare inhibitoriese aktiwiteit te kan uitvoer. Die projek het dus met behulp van kliek chemie, twee 1,2,3-triasool reekse gelewer wat omkeerbare en onomkeerbare inhibitoriese aktiwiteit kan uitvoer. Die verbindings gesintetiseerd in hierdie projek het keuringstoetse ondergaan teen die wilde tipe en teen twee gemuteerde forme van die EGFR kinase ensiem. Van hierdie verbindings het goeie selektiwiteit vertoon teenoor die gemuteerde EGFR kinase ensiem. Die mees aktiewe inhibeerder, N-{2-{[4-isokwinolin-4-iel)-1H-1,2,3-triasool-1-iel]feniel}akrielamied, het aktiwiteit in die lae μM reeks vertoon. Dié inhibisie waarde is vergelykbaar met die FDA goedgekeurde medikasie, gefitinib. In hierdie projek is sintetiese metodes ontwikkel wat toegepas kan word op meer intensiewe biologiese ondersoeke en asook meer navorsing. Die resultate vekry van die biologiese aktiwiteit, asook die verbindings se selektiwiteit, gee die moontlikheid vir die ontwikkeling en sintese van 'n tweede generasie verbindings.

Reaction of the pyrrolidine dienamines of ~1,8a-2-octalones with methyl vinyl ketone is complex. In methanol as solvent, the reaction occurs primarily with the linear dienamine isomer and results in annulation of the 8,8a-positions and, to a lesser extent, the 1,2-positions to give the corresponding octahydro-1 Hbenzo[d]naphthalene-2,10(3H,111-1)-dione and 3,4,5,6,7,8,8a,9-ctahydrophenanthren-2(10H)-one respectively. In toluene the dienamines react mainly in their cross-conjugated form. Diels-Alder addition of methyl vinyl ketone occurs across the 3,8a-positions to give the corresponding 9-acetylperhydro-2,4aethanonaphthalen-3-one and annulation of the 2,3-positions gives the 4,4a,5,5a,6,7,8,9-octahydroanthracen-2(3H)-one. The reaction of methyl vinyl ketone with the pyrrolidine dienamine of 4amethyl- 5-oxo-~ 1,8a-2-octalone is reported to give the aromatic product 3a, 7dimethyl- 2,3,3a,4,5,6-hexahydrophenalen-3,6-dionearisingfromp,o-annulation and in a related investigation with dienamines derived from isophorone it was reported that only products of Stork alkylation and Diels-Alder cycloaddition were isolated, there being no evidence for the reaction of methyl vinyl ketone with either the endo- or exocyclic o-positions of the dienamines. In an attempt to ascertain the reason for the apparently random changes in the regioselectivity of these related reactions some of this work was repeated and the reaction of methyl vinyl ketone applied to two other dienamines derived from 5,6,7,7a-tetrahydroindan-5-one and 4a,6-dimethyl-5-oxo-~1,8a-2-octalone. The reactions proved to be more complex than reported and several additional products have been isolated. Finally, reaction of phenyl vinyl ketone with dienamines derived from a1,8a_2-octalone was investigated. With the exception of the reaction of the 4amethyl dienamine, the main products isolated were those arising from addition of p.henyl vinyl ketone across the 3,8a-position to give the corresponding 9-benzoylperhydro-,4a-ethanonaphthalen-3-one. Reaction of the 4a-methyl dienamine with two equivalents of phenyl vinyl ketone gave a product tentatively assigned as the octahydrophenalenone. The mechanism of formation and spectral properties of the various products are discussed.
Thesis (Ph.D.)-University of Natal, 1991.