In this study, the reassociation kinetics of codling moth (Cydia pomonella) was performed in order to characterize the molecular composition of the codling moth (Cydia pomonella) genome and to isolate highly repetitive and unique DNA components. The effectivity of distinct repetitive DNA fractions as a specific competitor in fluerescence in situ hybridization was tested.

Please read the abstract in the section 00front of this document / Dissertation (M Eng (Metallurgical Engineering))--University of Pretoria, 2006. / Materials Science and Metallurgical Engineering / unrestricted

Tato dizertační práce se zabývá studiem morfogeneze dimethakrylátových sítí. V práci byly využity zjednodušené systémy založené na monomerech, které bývají typicky využívány jako složky matric pryskyřičných kompozitních materiálů využívaných v oblasti záchovné stomatologie. Kinetika a mechanismy formování polymerních sítí byly studovány především s ohledem na strukturu jednotlivých monomerů, jejich vzájemný molární poměr a koncentraci iniciačního systému využitého pro radikálovou polymeraci. Vypočtené profily konverze funkčních skupin a reakčních rychlostí byly využity jako základ pro pochopení a interpretaci mechanismů morfogeneze sítí a porovnání se známými modely. Dále byla studována kinetika termické degradace, která je s morfologií vytvrzených sítí přímo spjata. V rámci takto charakterizovaných systémů byla stanovena teplotní závislost dynamického modulu a byl popsán vztah mezi supra-molekulární strukturou dimethakrylátových sítí a jejich viskoelastickou odezvou v daném teplotním rozmezí. Kinetika polymerace byla studována pomocí diferenční kompenzační foto-kalorimetrie (DPC) a infračervené spektroskopie (FTIR). Proces termické degradace byl analyzován pomocí termo-gravimetrické analýzy (TGA). Viskoelastické parametry byly charakterizovány pomocí dynamicko-mechanické analýzy (DMA). Reaktivita jednotlivých systémů je přímo odvozena od molekulární struktury monomerů, která ovlivňuje mobilitu reagujících složek v průběhu polymerace. Kinetika polymerace je řízena především difúzí, přičemž její rychlost je dána tuhostí monomerní páteře, koncentrací funkčních skupin a vlivem fyzikálních interakcí. Omezená mobilita rostoucích řetězců, postranních funkčních skupin i samotných monomerů vede k monomolekulární terminaci makro-radikálů a omezení stupně konverze funkčních skupin. Vzhledem k tomu, že k zásadnímu omezení mobility dochází již v počáteční fázi polymerace, tj. v bodu gelace, je případná termodynamická nestabilita vedoucí k fázové separaci polymerujícího systému potlačena a proces kopolymerace je ve své podstatě náhodný. To bylo prokázáno i prostřednictvím identifikace jedné teploty skelného přechodu u charakterizovaných kopolymerů. Heterogenní charakter morfogeneze je spjat s rozdílnou reaktivitou postranních funkčních skupin. V počátečních fázích polymerace dochází k propagaci reakcí postranní funkční skupiny s radikálem na stejném rostoucím řetězci, což vede ke vzniku tzv. primárního cyklu. Pravděpodobnost cyklizace souvisí především s flexibilitou monomerní páteře. Heterogenita polymerace je charakterizována vznikem vnitřně zesítěných struktur, tzv. mikrogelů, a jejich následným spojováním. Tuhost monomeru naopak přispívá k vyšší efektivitě zesítění a více homogenní morfologii vytvrzené sítě. Heterogenita dimethakrylátových sítí se odráží v mechanismu termické degradace, přičemž přítomnost strukturně odlišných domén vede k rozkladu ve dvou krocích. Průběh soufázového modulu a teplota skelného přechodu korelují s tuhostí polymerních sítí, efektivitou zesítění a přítomností fyzikálních interakcí, které vyztužují strukturu sítě nad rámec kovalentního zesítění. Heterogenní morfologie sítí se projevuje rozšiřováním spektra relaxačních časů. Experimentální data jsou v kvalitativní shodě s existujícími numerickými modely popisujícími kinetiku radikálové polymerace multifunkčních monomerů.

Aim of magister´s thesis was to study reaction kinetics of dental materials. Thesis was focused on dimethacrylate dental polymers, which are for example used for dental restoration, tooth repair and creating now teeth. First part of the thesis concentrates on influence of molar ratio on reation kinetics by addition of other monomer to polymer resin. Second part concentrates on influence of addition of additive silica on reaction kinetics of polymerization. Essential variables know as a polymerization ratio, conversion, gel point, glass transition temperature and storage modulus were studied. Firstly, polymerization ratio and conversion were observed by differential scanning calorimetry (DSC). Secondly rheology was observed by photoreometr. Finally, glass transition temperature and storage modulus were observed by dynamic mechanical analysis (DMA). Behaviour changes caused by addion of monomer or filler point out decrease of polymeration ratio and converstion. Same behaviour was observed by short exposure. In order to established network formation, values of gel point increased by higher concentration of monomer or filler. Glass transition temperature and storage modulus measured by DMA were evaluated. Those valuables had variable tendency due to monomer acting like filler at higher concentration. Also contradictory impact of different material conversion and filler concetration was discussed.

In the general part of this diploma thesis are presented technical information collected on the issue of spontaneous decay of ozone in water solution and problems with analytical monitoring of these processes. Particular attention is paid to influence of pH value, bicarbonate and peroxide concentration on ozone decay kinetics. Experimental part is focused on the use of spectrophotometry in the study of chemical reactions associated with the spontaneous decay of ozone in distilled and tap water depending on pH and temperature after saturating of water by ozone prepared from air and pure oxygen. Direct photometry in UV range of spectrum (at 260 nm) was used to monitoring of ozone decomposition kinetics.

The decaying plasma was studied by the optical emission spectroscopy. DC discharge created at 45 – 200 mA in Pyrex and Quartz tubes in flowing regime was used. The emission of three nitrogen spectral systems (1st and 2nd positive and 1st negative) were studied in time evolution for pressures of 500 – 5 000 Pa at two wall temperatures – ambient and liquid nitrogen (150 K inside the decaying plasma). Results showed that all three nitrogen systems (respectively N2(B, v), N2(C, v) and N2+(B, v) states as their origins) had their population maxima called pink-afterglow in the afterglow part. These maxima decreased with the increase of pressure for all systems, and moved to the later decay time. Maxima increased with discharge current (respectively power) and moved to shorter time. Populations at temperature of 150 K were measured due to the experimental arrangement from 17 ms, only, and thus pink aftergow maximum wasn’t observed (only at 5 000 Pa some maximum was recognized). Populations were smaller at 150 K that populations measured at laboratory temperature at the middle decay time (50-100 ms). At the late time, the populations were higher at lower temperature at lower pressure. Higher shifts (in intensity and decaytime) of pink afterglow maxima were observed in Quartz tube in comparison with their values in Pyrex tube. Besides the populations, rotational temperatures of selected bands of three observed spetral systems (for 1st negative 0-0 band, 1st positive 2-0 band and for 2nd positive 0-2 band) were measured. Rotational temperatures were monitored from presumption that this kind of temperature is equal to temperature of neutral gas (at local thermodynamic equilibrium). Results from 1st negative and 1st positive system showed strong decreasing of rotational temperatures up to about 10 ms at post-discharge begin, then temperatures were constant up to 20 ms of decay time and after that they grew up. Temperatures increased with the increase of current. The part with decreased temperature correlated with pink-afterglow part of post-discharge. Unfortunately, rotational temperatures of 2nd positive system had bad reproducibility and the time profile shape was opposite. Experimental results were compared with numerical kinetic model created by group of prof. Vasco Guerra at Instituto Supetior Técnico in Portugal. Several sets of conditions for simulation at 500 and 1 000 K in active discharge were applicable for the calculation corresponding to the experiment. Comparison of numerical simulation and experimental data done for N2(B) state demonstrated that maxima populations in pink afterglow are depended on the temperature difference between active discharge and post discharge. Maxima populations were supposed in pink afterglow disappeared if the same temperatures in active and post discharges were supposed. Temperature in active discharge is higher at higher apllied power, as it was showed from rotational temperatures observation. The results clearly showed that real temperature profile must be included into the kinetic model.

This Ph.D. thesis is focused on kinetic study of propene and hex-1-ene coordination polymerizations initiated by complex [(2-tBuC6H4)N=C(1,8-naphtalenediyl)C=N(2-tBuC6H4)]NiBr2 activated by simple organoaluminium compounds and on product properties. In first three parts proper activators are chosen in model polymerizations. The attention is paid to the reproducibility of polymerizations and analytical methods. The fourth part is focused on propene polymerization kinetics with the aim to define optimal reaction conditions, especially polymerization temperature and time. The four part concerns also properties of polymers. The fifth and sixth parts deal with hex-1-ene polymerization kinetics conducted at various activator/initiator molar ratios and various catalytic precursor concentrations, to find out kinetic orders with respect to catalyst and cocatalyst concentration. Last part is oriented on detail mechanistic investigation of nickel diimine complexes activation process. Results of measurements in presence or absence of monomer enabled to propose new interpretation of UV-vis spectra based on concrete structures of absorbing species.

The first part of the thesis discuss general characterization of heterogeneous processes in silicates. This part is focused on kinetics of heterogeneous processes and mathematical description of reactions time behavior. The other part describes important technologies in silicate industry such as sintering, solid matter decomposition, transition modification, etc. Another chapter deals mineralogy, structure and properties of eminent silicate raw materials. Emphases is given to characterization of clay minerals and their utilising. The experimental part handle the analytic techniques used for investigation of thermal decompostion, dehydroxylation, crystalization of Al-Si spinel phase and sintering process of washed kaolin Sedlec Ia from the region Carlsbad (Czech Republic). Concluding chapter reports on results of experimental work.

The main topic of this thesis is a catalytic oxidation which belongs to a group of modern technologies for removing emission of CO and VOC from waste air. In the introduction of this thesis, the basic concepts are defined. Further the legislative requirements associated with VOC emissions, emission limits and conditions are summarized. Described destructive and non-destructive methods for removing VOCs from waste gases are also briefly described. Increased attention is paid to the catalytic oxidation as the main theme of the thesis. It was searched for industrial applications where the catalytic oxidation is used. Another chapter is devoted to the theoretical analysis of kinetics of catalytic oxidation reactions. Firstly, the basic types of reactors are described and also material balance and reaction rate for the isothermal and adiabatic reactor. In the experimental part results of performed kinetic measurements on a pilot unit for catalytic commonly used organic solvents (VOCs) using commercially available catalysts were summarized. Pre-exponential factors and activation energies for sprinkling catalysts EnviCat VOC-5565 and EnviCat 55068 for substances ethanol, toluene and acetone were determined. "Light-off" curves for these substances and methane were measured and on sprinkled catalyst EnviCat 55068 and on monolithic catalyst Purelyst PH-304.

<p>U okviru ovog istraživanja ispitani su: (1) Procesi koji se odvijaju prilikom &nbsp;bioremedijacije zemlji&scaron;ta zagađenog naftom i derivatima nafte, koje je bilo izloženo&nbsp;spontanim abiotičkim i biotičkim procesima degradacije u toku 8 godina, tehnikama&nbsp;biogomila i povr&scaron;inske obrade na poluindustrijskoj (pilot) skali uz optimizaciju&nbsp;tehnolo&scaron;kih parametara sa ciljem povećanja efikasnosti i efektivnosti biodegradacije&nbsp;ugljovodonika; (2) Uticaj starenja, koncentracije, biodsotupnosti i strukture zagađujućih&nbsp;materija na procese biodegradacije i biotransformacije u kontrolisanim laboratorijskim&nbsp;uslovima. Tokom dve godine bioremedijacionog tretmana sadržaj mineralnih ulja opao&nbsp;je za 52% (od 27,8 g/kg do 13,2 g/kg) i 53% (od &nbsp;23,2 g/kg do 10,8 g/kg), dok je sadržaj&nbsp;ukupnih ugljovodonika opao za 43% (od 41,4 g/kg do 23,4 g/kg) i 27% (od 35,3 g/kg do&nbsp;25,8 g/kg) u biogomili i povr&scaron;inskoj obradi respektivno. Efikasnost uklanjanja&nbsp;mineralnih ulja iz zemlji&scaron;ta u dva posmatrana bioremedijaciona tretmana je praktično&nbsp;ista. Međutim, u pogledu sadržaja ukupnih ugljovodonika u biogomili uklonjeno je dva&nbsp;puta vi&scaron;e ukupnih ugljovodonika (gledajući &nbsp;apsolutnu količinu ukupno uklonjenih&nbsp;ugljovodonika). Kinetika biodegradacije mineralnih ulja i ukupnih ugljovodonika u toku&nbsp;tretmana u biogomili u saglasnosti je sa kinetičkim modelima lnC=lnC_0-kt i lnC=lnC_0-kt^0,5. Kinetika biodegradacije mineralnih ulja u toku povr&scaron;inske obrade relativno se&nbsp;dobro može opisati sa dva pomenuta kinetička modela, međutim, znatno bolju&nbsp;korelaciju pokazao je linearni model (C=C_0-kt) primenjen na prvih 92 i poslednjih 200&nbsp;dana eksperimenta. Promena sadržaja ukupnih ugljovodonika u toku povr&scaron;inske obrade&nbsp;zagađenog zemlji&scaron;ta relativno je u dobroj korelaciji samo sa kinetičkim modelom&nbsp;lnC=lnC_0-kt^0,5. Laboratorijska ispitivanja pokazala su da biodegradabilnost i sudbina&nbsp;ugljovodonika u životnoj sredini jako zavise od tipa, starosti i koncentracije zagađujućih&nbsp;materija. Naime, u slučaju zemlji&scaron;ta sveže kontaminiranog dizel uljem, već pri&nbsp;<br />koncentracijama od 20 mg/g uočen toksičan efekat koji je prevaziđen nakon dve nedelje&nbsp;tretmana kao posledica smenjenja prekomerne koncentracije rastvorenih ugljovodonika&nbsp;biotičkim i abiotičkim putem i adaptacije prisutne mikroflore. U slučaju većih&nbsp;koncentracija ovaj efekat je bio jo&scaron; izraženiji. Kod zemlji&scaron;ta kontaminiranog sirovom&nbsp;naftom isti efekat se javlja tek pri koncentraciji od 35 mg/g, kao posledica toga da&nbsp;sirova nafta sadrži manju količinu lako rastvornih ugljovodonika. Za razliku od sveže&nbsp;kontaminiranog zemlji&scaron;ta, na biodegradaciju starog naftnog zagađanja u zemlji&scaron;tu&nbsp;koncentracija nije imala uticaj, u ovakvom zemlji&scaron;tu respiracija je bila na veoma niskom&nbsp;nivou pri svim ispitivanim koncentracijama, ali ne kao posledica toksičnosti, već kao&nbsp;posledica činjenice da se degradabilni deo zagađujućih materija degradirao tokom&nbsp;procesa starenja, tako da su u zemlji&scaron;tu zaostali visokomolekularni &nbsp;te&scaron;ko rastvorni&nbsp;ugljovodonici (smole, asfaltne komponente i dr.) sekvestrovani u zemlji&scaron;tu. Merenja biodostupnosti ugljovodonika (ekstrakcijom sa Tween80) pokazala &nbsp;su da je u zemlji&scaron;tu sveže kontaminiranom dizel uljem i sirovom naftom i starim naftnim zagađenjem oko 95%, 85% i 40% ugljovodonika biodostupno, respektivno. Koncentracija rezidualne frakcije mineralnih ulja i ukupnih ugljovodonika dobijena nakon 48 dana laboratorijskog tretmana u skoro svim probama je veća od predviđenih, &scaron;to je posledica bifaznog pona&scaron;anja ugljovodonika u zemlji&scaron;tu, gde se jedan deo uklanja biodegradacijom, dok drugi deo difunduje u pore zemlji&scaron;ta i kompleksira se sa zemlji&scaron;nom organskom materijom. Količina ugljovodonika iz starog naftnog zagađenja zemlji&scaron;ta koja može da pređe u vodenu fazu je mala reda veličine nekoliko mg/l, međutim, u prirodnim uslovima usled spiranja ugljovodonika sa zemlji&scaron;ta ki&scaron;om, postoji verovatnoća da ovi ugljovodonici dospeju u podzemnu vodu iznad maksimalno dozvoljene koncentracije za vodu za piće (MDK = 10 &mu;g/l) i na taj način degradiraju njen kvalitet. Zbog nemogućnosti daljag uklanjanja zagađenja bioremedijacijom, preostala količina zagađujućih materija koja može dospeti u vodenu fazu bi trebalo da se ukloni nekim drugim remedijacionim tehnikama pre njegovog konačnog bezbednog odlaganja u životnu sredinu.</p> / <p>The aims of this study were to examine: (1) the processes that occur during bioremediation of soil contaminated by oil and oil derivatives, which was exposed to spontaneous abiotic and biotic degradation processes over 8 years, using pilot scale biopiles and landfarming techniques to optimise technological parameters with the aim of increasing the efficiency and effectiveness of hydrocarbons biodegradation. (2) the effect of contaminants weathering, concentration, bioavailability and structure on the biodegradation and biotransformation process under controlled laboratory conditions. Over the two years of bioremediation treatment by biopiles and landfarming, the mineral oil content decreased by 52% (from 27.8 g/kg to 13.2 g/kg) and 53% (from 23.2 g/kg to 10.8 g/kg),&nbsp; and the total hydrocarbon content decreased by 43% (from 41.4 g/kg to 23.4 g/kg) and 27% (from 35.3 g/kg to 25.8 g/kg), respectively. The efficiency of mineral oil removal from soil in these two applied bioremediation treatments was practically the same. However, in terms ofthe absolute amount of total hydrocarbons, twice as many total hydrocarbons were removed in the biopile. The mineral oil and total hydrocarbons biodegradation kinetics in the biopile were in good agreement with&nbsp; the kinetic models lnC = lnC0-kt and lnC = lnC0-kt0.5. The mineral oil biodegradation&nbsp;kinetics during the landfarming treatment is relatively well described with those two kinetic models, however, significantly better correlation is obtained by the linear model (C = C0-kt) applied to the first 92 and last 200 days of the experiment. The change in total hydrocarbons content during the landfarming treatment is in relatively good correlation only with the kinetic model lnC = lnC-kt0.5. The laboratory biodegradation investigation showed that hydrocarbon biodegradability and its fate in the environment strongly depend upon the structure, concentration and weathering of the hydrocarbons. Thus, in the case of diesel contaminated soil, as a consequence of&nbsp; its structure, i.e. the presence in a higher concentration of the soluble and toxic midrange n-alkanes, a toxic effect is detected at a diesel oil concentration of 20 mg/g, although this effect is overcome after two weeks, as a consequence of the decreasing&nbsp; concentration of soluble hydrocarbons in biotic and abiotic processes and microbial adaptation. This effect was more pronounced in the case of the soil withthe highest diesel oil concentration. In crude oil contaminated soil, a toxic effect was observed at a much higher hydrocarbon concentration (35 mg/g) than in the diesel oil contaminated soil, which corresponds to the fact that crude oil contains significantly less soluble hydrocarbon. In contrast to these two freshly contaminated soils, the weathered contaminated soil contaminant concentration did not have an effect on hydrocarbon biodegradation, with biodegradation in this soil actually at a low level at all concentrations, not as a consequence of toxicity, but because the degradable part of the contaminant was already degraded during the weathering process, leaving behind only highly condensed hydrophobic organic contaminants (asphaltenes, resins, etc.) sequestered in the soil. The data obtained for hydrocarbons bioavailability (by Tween80 extraction) showed that the bioavailable hydrocarbon fraction from soils freshly contaminated with diesel oil and crude and weathered oil contamination were approximately 95%, 85% and 40%, respectively. The concentration of residual mineral oil fractions and total hydrocarbons obtained after 48 days of laboratory biodegradability treatment in almost all batches was greater than predicted, as a result of the biphasic behaviour of hydrocarbons in the soil, where some were degraded or lost from the soil and some transformed into the recalcitrant fraction. The amount of hydrocarbons from the weathered soil contamination that can be transferred into the water phase is small, of the order of a few mg/l in magnitude, however, under natural conditions, due to hydrocarbons leaching by rainfall, it is possible that these hydrocarbons infiltrate groundwater above&nbsp; the maximum permissible concentration for drinking water (MAC = 10 &mu;g/l) and thus degrade its quality. As it is not possible to achieve further contamination degradation by bioremediation, the remaining amount of pollutants which can be transferred into the water phase should be removed by some other remediation techniques before its final safe disposal in the environment.</p>