Naive observers are found to estimate numbers of dots on projected slides with a consistent factor of underestimation of ca. 0.75. There is an overall difference in response between males and females and between more experienced and less experienced observers. There is an apparent trade-off between accuracy and precision when significant differences in response are recorded. Training observers with slides of revealed value alone is equally effective as a combination of slides and a reference pamphlet: both produce improvements in accuracy and precision. A subjective visual index of house fly abundance is found to be more sensitive than Scudder grill counts, spot cards, sticky tape traps or square-foot panels to changes in house fly population densities. None of these methods is consistently the best correlated to the visual index, although the square-foot panels were most highly correlated most often. / Ph. D.

Traditionally, coal combustion residuals (CCRs) were disposed of with little engineering consideration. Initially, common practice was to use a wet-scrubbing system to cut down on emissions of fly ash from the combustion facilities, where the ash materials were sluiced to the disposal facility and allowed to sediment out, forming deep deposits of meta-stable ash. As the life of the disposal facility progressed, new phases of the impoundment were constructed, often using the upstream method. One such facility experienced a massive slope stability failure on December 22, 2008 in Kingston, Tennessee, releasing millions of cubic yards of impounded ash material into the Watts Bar reservoir and damaging surrounding property. This failure led to the call for new federal regulations on CCR disposal areas and led coal burning facilities to seek out geotechnical consultants to review and help in the future design of their disposal facilities. CCRs are not a natural soil, nor a material that many geotechnical engineers deal with on a regular basis, so this thesis focuses on compiling engineering characteristics of CCRs determined by different researchers, while also reviewing current engineering practice when dealing with CCR disposal facilities. Since the majority of coal-burning facilities used the sluicing method to dispose of CCRs at one point, many times it is desirable to construct new "dry-disposal" phases above the retired ash impoundments; since in-situ sampling of CCRs is difficult and likely produces highly disturbed samples, a sample reconstitution technique is also presented for use in triaxial testing of surface impounded CCRs. / Master of Science

Yes / Fly ash is a toxic industrial waste, mainly consisting of silica and alumina particles, that has been found discharged into the environment. It is proposed that alginate, a naturally occurring biopolymer, can bind to these minerals and thus play a role in water purification. The binding forces involved in this process consist of weak interactions, such as van der Waals forces and electrostatic interactions. Although the attachment of alginate to mineral surfaces is mainly governed by its carboxylate groups, hydroxyl moieties could play a role in the interaction between the polymer and minerals. This work aims to use the SiO2 and Al2O3 particles as models for fly ash and to show the use of alginate biopolymers (fluorescently labelled with an aminonaphthaline sulfonate fluorophore (AmNS)) to coagulate them. The addition of simple electrolytes like NaCl and CaCl2 encourages the coiling of the polymer chain at high pH values which has an effect on its capability to bind to the inorganic particles. A combination of fluorescence and ICP-MS demonstrated that alginate has a considerable adsorption affinity for Al2O3, whereas it attracts SiO2 weakly. The adsorption process is pH dependent: strong adsorption was observed at low pH values. The dependence of adsorption on the mineral (Al2O3 and SiO2) concentration was also examined under different pH conditions: the adsorption amount was observed to increase by increasing the solid concentration. Adsorption isotherms obtained at low and high mineral concentrations were found to be Henry in type.

In an attempt to demonstrate the role of insects as possible carriers of pathogenic bacterial organisms this investigation has been concerned with the determination of the microbial population associated both internally and externally with the common house fly and three species of the cockroach.

This work includes two different areas of research. Both areas are related to the combustion of the binder-enhanced densified refuse derived fuel (bdRDF) with high sulfur coal and examining trace elements. The first area of this work involved studying the trace metals in the combustion gas of bdRDF/coal blend and the effect of the binder, CA(OH)2, on reducing the trace elements emissions. The second area of work involved studying the trace elements in the fly ash and the effect of the dRDF and the binder of trace metals.

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is well-known as a destructive pest of fruit worldwide. Various control methods have been used against this insect. The sterile insect technique (SIT) is used as an important and successful technological method for controlling or eradicating this pest in many countries. A key factor to successfully apply SIT is dependent on the availability of efficient and economical rearing methods. Artificial insect diets with low cost bulking agents have been of interest to many researchers. The present study investigated the use of locally available maize meal as a bulking agent in such diets. Maize meal is used for human consumption (in South Africa) and contains small amounts of protein. This makes the reduction of imported torula yeast as an ingredient of the diet and source of protein possible, thereby reducing the cost of the diet. The larval development of the Medfly reared on artificial diets was studied in small and large-scale tests. The effect of the diets on larval production was evaluated using pupal recovery, pupal weight, flight ability, sex ratio, fecundity and egg fertility. The results of the small-scale tests showed that the diet containing maize meal could be used to produce Medfly more economically than the standard Krige diet used by the ARC Infruitec-Nietvoorbij Research Institute at Stellenbosch. However, in large-scale tests the ingredients quantities of the diets used were not the same as those of small scale-tests. The cost of the modified larval diet was not reduced in large-scale tests. This was ascribed to the number of eggs used in the tests to produce one million of fruit flies. The maize meal with reduced number of eggs require more diet to produce one million flies therefore, making it more expensive and less viable. When similar amounts of eggs were used, the diet appears to be a suitable alternative as the result obtained was almost similar to those of the Krige diet. / AFRIKAANSE OPSOMMING: Die Mediterreens vrugtevlieg ("Medfly"), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is wêreldwyd 'n skadelike plaag. Die steriele insek tegniek (SIT) het in baie lande 'n belangrike en suksesvolle manier geword om die plaag te beheer en uit te roei. Die belangrikste voorvereiste vir die suksesvolle toepassing van SIT is die beskikbaarheid van doeltreffende en ekonomiese teelmetodes. Meeste navorsers is geïntereseerd in kunsmatige diëte met 'n goedkoop vulstof. Hierdie studie is ontwerp om die gebruik van plaaslik beskikbare mieliemeel as vulstof te ondersoek. In Suid-Afrika word dit vir menslike gebruik aangewend en bevat klein hoeveelhede proteïene wat 'n vermindering van die ingevoerde torula gis moontlik kan maak, en sodoende die koste van die dieët kan verminder. Die ontwikkeling van Medfly larwes op kunsmatige diëte is bestudeer In kleinskaalse en grootskaalse eksperimente. Die invloed van die diëte op larwale produksie is evalueer deur gebruik te maak van van papie-ontwikkeling, papie-gewig, vliegvermoë, geslagsverhouding, volwasse voortplantingsvermoë en eiervrugbaarheid. Die resultate van die kleinskaalse toetse het aangetoon dat die mieliemeel dieët gebruik kan word om Medfly meer ekonomies as met die standaard Krige dieët, wat in die ARC Infruitec-Nietvoorbij navorsings instituut by Stellenbosch gebruik word, te teel. By die grootskaalse toetse was die koste nie laer nie. Dit word toegeskryf aan die aantal eiers wat gebruik is om 'n miljoen vlieë te produseer. Die mieliemeel dieët met 'n verminderde aantal eiers benodig meer dieët om 'n miljoen vlieë te produseer, wat dit duurder en minder lewensvatbaar maak. Wanneer soortgelyke hoeveelhede eiers gebruik was, het dit geblyk dat die dieët 'n opsie is, want die resultaat was soortgelyk aan dié van die Krige dieët.

The use of fly ash as a supplementary cementitious material (SCM) has increased in the last century due to its various environmental benefits as a recycled product. Within the last 60 years, it has been found that it can be used to effectively control damage induced by Alkali-Silica Reaction. However, it is not completely understood how to properly assign a dosage of fly ash to control the reaction. This depends greatly on the fly ash characteristics (e.g. composition, particle size, and reactivity), the reactivity of the aggregate (e.g. high to low reactivity level) and the environmental exposure conditions. The characteristics of the fly ash depend on the coal source being burned and the burning conditions that result in the fly ash formation. A major concern when supplementing cement with fly ash for ASR mitigation is the effect of the alkali contribution of the fly ash to the concrete pore solution. Current test methods cannot accurately determine the alkali contribution of fly ashes and there is no standardized test method to doing so. When contributed by the implementation of a SCM, alumina has been found to play a role in the ability of an SCM to mitigate ASR-induced damage. It has been observed that fly ashes containing higher levels of alumina (18-25%) tend to improve concrete durabilty more effectively when compared to fly ashes with lower levels of alumina. Additionally, the use of metakaolin, which is composed of 45-50% alumina, has been found to lessen expansion with a lower percentage of cement replacement than would be required if fly ash is used. Furthermore, the use of fly ash with another SCM material, a high quality ultra-fine fly ash or alumino-siliceous metakaolin, in ternary blends may improve the performance of fly ash resulting in a broadening of the spectrum of SCMs usable for ASR mitigation. For successful use of SCMs, it is important to develop an understanding of the alkalisilica reaction and the ability of such SCMs to control expansion. This report provides an overview of alkali-silica reaction and the use of fly ash and metakaolin as SCMs to mitigate expansion due to the reaction, with an emphasis on the role of alumina when contributed from the two materials. / Graduation date: 2012

<p> <p>&nbsp / </p> <p align="left">&nbsp / </p> <p>&nbsp / </p> </p> <p align="left">The aim of this study was to produce useful composite materials from fly ash, a major waste product of coal combustion from power plants. Polyaniline-fly ash (PANI-FA) composites were prepared by in situ polymerisation of aniline in the presence of Fly Ash (FA) by two slightly different methods. In one case polystyrene sulphonic acid (PSSA) was used as a stabilizer and in another case the starting materials (aniline and FA) were aged before oxidation. The aging procedure formed nanotubes that have cross-sectional diameters of 50-110 nm. The other procedure produced nanotubes with a diameter of 100-500 nm and the length of up to 10&mu / m. The presence of metal oxides and silica in FA were responsible for the formation of nanorods in PANI-PSSA-FA.. The formation of the composites was confirmed by UV-Vis and FTIR. The UV-Vis showed maximum absorbance at 330-360 nm ( due to &pi / -&pi / * transition of benzoid rings) and 600-650 nm(due to charge transfer excitons of quinoid rings), which are characteristics of emaraldine base. The electrochemical analysis of the composites showed that the composites were conductive and electroactive. The Cyclic Voltammetry of PANI-PSSA-FA showed three redox couples which are characteristics of sulphonated PANI. The morphology of the composites was studied by Scanning Electron Microscopy (SEM) and showed that our methods gave composites with improved homogeneity as compared to other reported methods. Thermo Gravimetric analysis (TGA) showed that the presence of FA in the composites improves the thermal stability of the composites by up to 100 0C.<br /> &nbsp / </p>

No description available.

<p> <p>&nbsp / </p> <p align="left">&nbsp / </p> <p>&nbsp / </p> </p> <p align="left">The aim of this study was to produce useful composite materials from fly ash, a major waste product of coal combustion from power plants. Polyaniline-fly ash (PANI-FA) composites were prepared by in situ polymerisation of aniline in the presence of Fly Ash (FA) by two slightly different methods. In one case polystyrene sulphonic acid (PSSA) was used as a stabilizer and in another case the starting materials (aniline and FA) were aged before oxidation. The aging procedure formed nanotubes that have cross-sectional diameters of 50-110 nm. The other procedure produced nanotubes with a diameter of 100-500 nm and the length of up to 10&mu / m. The presence of metal oxides and silica in FA were responsible for the formation of nanorods in PANI-PSSA-FA.. The formation of the composites was confirmed by UV-Vis and FTIR. The UV-Vis showed maximum absorbance at 330-360 nm ( due to &pi / -&pi / * transition of benzoid rings) and 600-650 nm(due to charge transfer excitons of quinoid rings), which are characteristics of emaraldine base. The electrochemical analysis of the composites showed that the composites were conductive and electroactive. The Cyclic Voltammetry of PANI-PSSA-FA showed three redox couples which are characteristics of sulphonated PANI. The morphology of the composites was studied by Scanning Electron Microscopy (SEM) and showed that our methods gave composites with improved homogeneity as compared to other reported methods. Thermo Gravimetric analysis (TGA) showed that the presence of FA in the composites improves the thermal stability of the composites by up to 100 0C.<br /> &nbsp / </p>