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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

A structural study of translucency in soap bars

Taylor, Stefan Colin John January 2001 (has links)
This thesis concerns the manufacture of translucent soap bars. Current methodologies for the production of such marketable products are expensive and time consuming (e.g. hot-melt processes). Translucent soap bars may also require dramatic shifts in composition away from more traditional opaque products (e.g. high glycerine content), leading to undesirable physical properties such as a poor rate of wear.

Phosphorus dynamics and agronomic responses in Irish grassland soils

Sheil, Timothy January 2015 (has links)
Phosphorus (P) is an essential element for grassland productivity, but P fertilizers are mined from finite resources of phosphate rock. As a result, there is growing interest in increasing the efficiency of P fertilizer !use in agriculture to ensure the future sustainability of food production. This project was designed to increase our knowledge on the behaviour of, and requirements of P in grassland soils. The results which include data from a long-term field experiment showed that a sustained annual application of 15 kg P ha-1 y(l was required for maximum herbage yield whilst seasonal trends indicated that P concentration in herbage was lowest during the summer months. Results from a field experiment which examined the effects of N, P and lime on two sites with contrasting soil fertility levels found a comparable response to nitrogen and P on the herbage yield while soil P levels had a strong influence on herbage P concentration. A soil incubation experiment carried out on a range of different Irish soils showed that lime plays an important role in increasing the availability of soil P and fertilizer P. In the same range of soils the examination of soil organic P was investigated and the results highlight the variation that exists in organic P species in Irish soils. Overall the results from these experiments suggests that as the future availability of P fertilizer becomes uncertain, a greater emphasis on soil specific fertilizer P guidelines will be required to maximise P efficiency in grasslands. This project will underpin the rationale and provide initial results which will aid the future implementation of a more soil specific P fertilizer guidelines in Ireland. Furthermore maintaining soil P fertility is a crucial if agriculture is to achieve the productivity targets set by a growing world population.

Role of riverbank filtration in the attenuation of herbicides

Bao Son, Trinh January 2010 (has links)
This thesis for the first time reports the fate and behaviour of herbicides mecoprop (MCPP) and isoproturon (IPU) in the hyporheic zone of a river bank. Two laboratory studies based on fixed-bed circulation and 14Crespirometry were developed to investigate the attenuation of the two herbicides in riverbank filtration (RBF), a means of pre-treatment of drinking water obtained from bank-side boreholes. The first laboratory study investigated the sorption and biodegradation of MCPP and IPU (100 μg L-1) in a river water (RW)-riverbed sediment (RS) system with materials obtained from a site on the River Thames at Gatehampton, England. Using a fixed-bed circulation method, approximately 18-20 % of the herbicides were removed by sorption, with the remainder removed by a high rate of biodegradation during 14 circulating days. The RS-borne microorganisms played a primary role in the biodegradation process of these herbicides, while the RW-borne microorganisms contributed very little. In addition, after a period of incubation (by 18 circulation days with IPU) the RS-borne microorganisms were able to immediately mineralise 14C-IPU (29.4 % 14CO2) while the RW-borne microorganisms were not competent to do so (1.6 % 14CO2). The second laboratory study investigated catabolic insights into IPU degradation in river water (RW), groundwater (GW) and riverbed sediment (RS). Very low maximum levels of mineralisation of IPU were observed in RW (0.4 % 14CO2) and GW (1.2 % 14CO2) while very high maximum level of mineralisation of IPU was obtained in RS (14.5 % 14CO2). Furthermore, the catabolic competence with respect to IPU was enhanced with increasing the IPU-dosed concentrations (ranging 1 – 100 μg L-1) in RS microcosm. By plotting the maximum mineralisation levels versus the residual IPU concentration (after various periods of incubation), a logarithm linear relation between the maximum mineralisation levels and IPU concentrations was obtained. This relationship suggested that higher mineralisation levels are achieved for higher IPU concentrations. Nonetheless, the catabolic activity not only was not significantly enhanced (p > 0.05) after a period of incubation (0 – 10 days) but also was greatly decreased (p < 0.05) after 30 incubation days. Based upon the experimental results, to remove the herbicides from 1 L of RW contaminated with MCPP and IPU (up to 100 μg L-1), a required volume of RS (bulk density of 1.25 ± 0.02 g cm-1 and porosity of 50.6 %) was determined to be 0.027 m3. Extent in a RBF context, it is suggested that a bank-side borehole with a capacity of 16 x 106 L day-1 and 25 % river-fed water could be protected from the river-borne herbicide pollution (up to 100 μg L-1) if the borehole is located at a minimum distance (path length) of 400 m from the river with the thickness of a RS layer to be 6 m. Collectively, the herbicides MCPP and IPU were completely degraded in a hyporheic zone of a river bank. Microorganisms originated from RS played a pivotal role in the degradation. This demonstrated that RBF is potentially a highly efficient pre-treatment method which can totally remove herbicide pollution in river. Hence, bank-side boreholes which are mainly or partly fed by induced RW may be benefit from this natural attenuation process.

Structure-property relationships in water-borne, crosslinked, acrylic pressure-sensitive adhesives

Errington, Nicola January 2001 (has links)
Five series of acrylic water-borne pressure-sensitive adhesives (PSA's) were prepared with controlled particle morphologies, including core-shell and continually-varying composition. All latex adhesives were prepared at 50 % solids content by emulsion polymerisation of n-butyl acrylate (BA) and acrylic acid (AA) as the main monomers and 1,6-hexanediol diacrylate (HDA) as a crosslinking agent. Seed particles of poly(butyl acrylate) (PBA) were grown by an in-situ batch process to produce a particle of diameter 110 nm. Direct growth of these particles by a semi-continuous process under monomerstarved conditions was employed to give a final particle diameter of approximately 310 nm. Preliminary investigations were aimed at preparation of a latex with a narrow particle size distribution and a low level of coagulum. Initial work using 2-ethylhexyl acrylate (EHA) as the main monomer was not successful because a stable 50 % solids latex could not be produced with controlled particle growth. Hence a formulation was developed using BA and AA. Three series of latexes were prepared with a core-shell particle morphology. Series 1 involved the investigation of the level of crosslinker in the core, at fixed 45:55 core:shell weight ratio, with HDA levels ranging from 0 to 37.5 mol%. Series 2 investigated the volume fraction of crosslinked core (containing 33.3 mol% HDA) over the range 55:45 to 15:85 core:shell weight ratio. Series 3 investigated the effects of the thickness of a crosslinked shell (9.1 mol% HDA) for core-shell particles with a noncrosslinked core (at 55:45, 75:25 and 90:10 core:shell weight ratios). Series 4 latexes were prepared using power-feed processes, one linear power-feed and three based on Series 1 and 2 core-shell adhesive compositions. An additional latex was prepared with a particle profile in which the composition changed linearly with particle radius. Series 5 adhesives were blends of two latexes, such that the mixture had the same composition as Series 2 core-shell adhesives and consisted of the 'core' of the core-shell adhesive blended with a latex with the same composition as the shell of the respective core-shell adhesive. Latex preparation was controlled and monitored by measuring the particle size and the conversion of monomer to polymer at intervals during the preparation. Thermal properties of the adhesives were investigated for thick film samples by dynamic mechanical analysis {DMA}to measure the glass transition temperature {Tg}. Differential scanning calorimetry {DSC}was also used to measure Tgfor comparison. DMA showed two Tg's corresponding to the core and the shell. As the level of crosslinker was increased, the two Tg's became more discrete due to the Tg of the crosslinked phase increasing. The magnitude of the peaks in loss tangent {tan 5} for the core and shell material changed in accordance with the ratio of core:shell. Power-feed adhesives showed a broad glass transition region, which spanned the regions between the Tg's of the equivalent core-shell adhesive. The peaks in tan 5 for the blended systems were more discrete than for the equivalent core-shell adhesives. Adhesive properties were assessed using shear resistance and 1800 peel adhesion tests. Static shear tests were inadequate for testing highly-crosslinked adhesives; hence a dynamic shear resistance test was developed. In comparison to a uniform {noncrosslinked} poly(butyl acrylate-eo-acrylic acid} (PBAlAA) latex, inclusion of crosslinker led to vastly reduced peel adhesion. However, as the level of crosslinker was increased in the Series 1 adhesives, both the peel adhesion and the shear resistance increased. Series 2 and 3 latexes showed that the peel adhesion increases as the amount of non-crosslinked phase is increased. Series 2 adhesives exhibited a maximum in the shear resistance, while Series 3 adhesives showed a decreased in shear resistance as amount of non-crosslinked! ehe core was increased. Adhesive properties of Series 4 power-feed latex polymers showed no dependence on overall crosslink density, but revealed that there is a dependence on the distribution of crosslinker through the particle.

Investigating hydrotropes

Naz, Asma January 2014 (has links)
Hydrotropes are small, short-tailed amphiphiles that strongly enhance the aqueous solubility of hydrophobic compounds otherwise sparingly soluble, after a minimum hydrotrope concentration. The hydrotropic effect of the molecules representative of all three classes of hydrotropes was examined, in terms of the solubilisation efficiency of these molecules to dissolve pyrene. Pyrene was chosen as a standard hydrophobic compound. The selected series of cationic hydrotropic compounds consisted of tetraalkylammonium chlorides, with increasing hydrophobic character, by the introduction of a -CH2- to each of the four alkyl groups, in order to make every next homologue of the series. The anionic hydrotrope series comprised of structurally related aromatic carboxylates. All of the examined hydrotropes exhibited a linear rise in the solubility of pyrene with the increase in the concentration of the hydrotrope, irrespective of the class. The hydrotropic effect of the amphiphiles of all three series, designed and examined here, was scrutinized in terms of alterations in the properties of micellar and lyotropic mesophases, of a chosen, systematic and sequenced set of non ionic surfactants, in the aqueous medium. A parallel and comparative study was made using a standard inorganic salt, NaCI. Hydrotropes displayed a demotion in the aggregation of micellar phase of nonionic surfactants compared to the growth of micelles caused by the NaCI. The mechanism was found to involve comicellisation of hydrotropes in to the nonionic micelles, The destabilization leading to fluidization of lyotropic mesophases, while preventing phase separation, of the aqueous non ionic surfactants studied, was another effect caused by all of the hydrotropes universally.

Development of soil conditioner from co-granulation of waste material with limestone powder in a high shear mixer

Liu, Jiang Tao January 2016 (has links)
The main aim of this research was to investigate the feasibility of producing an organic fertiliser using waste materials and limestone powder as the raw materials using the process of high shear granulation. The waste materials are anaerobic digest tea waste and sodium-based lignosulfonate. Successful production of improved soil conditioner would reduce the amount of synthetic fertiliser for farm application. It would also provide a sustainable way of managing waste. Two factorial experimental design was used to determine the effect of process and formulation variables on the strength, size distribution, resistance to attrition yield of the granules and nutrient homogeneity of the granules. Additional understanding of the granulation process in the high shear mixer involving binary powder mixes with different physical characteristics was provided.

The bacterial degradation of aryl-sulphonates and related detergent compounds

Farr, D. R. January 1968 (has links)
No description available.

Synthesis of isotopically labelled nicotinanilides and evaluation of their molluscicidal properties

Dunlop, Robert William January 1976 (has links)
No description available.

The fractionation of gum arabic using synthetic membranes

Manning, Harriet January 2015 (has links)
Gum arabic is a natural product used widely in the food industry as an emulsifier and stabilising agent. The gum contains 3 main fractions: an arabinogalactan (~80 wt%; AG) fraction, a glycoprotein (~ 2 wt%; GP) fraction and an arabinogalactan-protein complex (~18 wt%; AGP). This AGP fraction is largely responsible for the functional properties of gum arabic and, due to natural variation, the proportion of AGP within a gum arabic batch varies enormously. There is industrial interest, therefore, in fractionating the gum arabic to allow creation of a more homogenous product, as well as new products for the food industry. The aim of this work was to investigate the feasibility of using membrane technology to fractionate gum arabic. Polymeric membranes were used initially and showed success at rejection of AGP by size exclusion. Polysulfone membranes of 0.1, 0.5 and 0.8 μm nominal pore size were employed and the rejection of AGP was seen to decrease with increasing pore size, but the overall transmission of solids was seen to increase. Beneficial fouling was observed with the larger two pore sizes, which allowed greater fractionation after a fouling layer had developed. It was hypothesised that the 0.1 μm PS membrane was fouled by mainly cake formation, whereas the 0.5 and 0.8 μm PS membranes were subject to more in pore fouling. The critical flux of gum arabic was measured for these three pore sized membranes and was found to be highest (27 L m-2 h-1) for the 0.1 μm PS membrane. This was attributed to the lack of in pore fouling, which the 0.5 and 0.8 μm membranes suffered and resulted in fouling occurring at lower fluxes for these membranes; the critical fluxes for these membranes was found to be 15 and 22 L m-2 h-1, respectively Increasing the crossflow velocity (CFV) from 0.18 to 0.67 m s-1 was found to increase the critical flux. Filtration experiments above and below the critical flux for each pore size demonstrated the efficiency of operating below the critical flux, as operation could be sustained for much longer periods (up to 4h was tested) without the need for cleaning cycles. It also demonstrated the beneficial effect of the fouling layer with the 0.5 iii and 0.8 μm membranes, which showed little or no fractionation during operation below the critical flux. Finally, filtration studies were carried out with 3 different membrane materials and detailed surface analysis was performed to explain the differences in performance observed. Both polysulfone and fluoropolymer membranes were fairly hydrophobic, with contact angles of between 70 and 90º, and showed very high overall rejection of solids. High transmission of solids is required together with good rejection of AGP for an effective fractionation process. Hydrophilic cellulose acetate, however, showed very high transmission of gum arabic (~ 75%), but no rejection of AGP. Overall, the work has shown that fractionation of gum arabic with membranes is feasible using polysulfone membranes, but that further work is needed to optimise the separation. Higher transmission of the GP and AG are required whilst maintaining rejection of the AGP.

The uptake, translocation and metabolism of the triazine herbicide, cyanazine (2-(4-chloro-6-etylamino-s-triazine-2-ylamino 2-methylpropionitrile)) by wheat, blackgrass and turnip seedlings

Priest, Bernard January 1976 (has links)
Cyanazine activity against wheat, blackgrass and turnip seedlings, grown in soil, sand or liquid culture, was investigated under glasshouse conditions. Post-emergence foliar applications of cyanazine were seriously phytotoxic to turnip alone, but regular rewetting of foliar deposits significantly increased phytotoxicity to wheat. Cyanazine applied postemergence to the soil surface entered wheat via the roots alone, whereas in turnip entry occurred both through the root and sub-surface shoot. Entry of soil-applied cyanazine into blackgrass was largely confined to adventitious roots developed close to the soil surface, Selectivity was related to differences in intrinsic tolerance and rate of uptake from soil. Wheat tolerated tissue concentrations five to six times those tolerated by blackgrass or turnip, and unlike them, was incapable of absorbing cyanazine from soil above seed level. However, due to its high transpiration rate, wheat rapidly accumulated high concentrations of cyanazine when the roots were exposed to the herbicide. Increasing the soil water content or reducing the seed depth encouraged exposure of the root system and considerably reduced selectivity. Selectivity was unrelated to differences in translocation, but inactivation within the tissues was slower in wheat than the other species. Phytotoxicity was related to stage of growth at treatment. Susceptibility to soil-applied cyanazine increased temporarily as photosynthetic tissues were first formed, but decreased steadily thereafter. Susceptibility of turnip, to foliar applications, decreased slightly as foliage density increased, reducing the percentage of leaf area exposed, but that of wheat and blackgrass increased as the leaves became larger and less erect. Selectivity was greatest at the very early seedling stages, and decreased steadily thereafter. Measurements were made of persistence and movement of cyanazine in soil, and of its effect on transpiration.

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