- 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.
Search results
Showing 101 to 110 of 111 (0.067 seconds)Spelling suggestions: "subject:"preservatives"" "subject:"preservative""
| 101 |
Avaliação da atividade antimicrobiana de extratos de folhas de Lippia salviaefolia Cham. visando sua aplicação como conservante em preparações cosméticas / Evaluation of the antimicrobial activity of leaf extracts of Lippia salviaefolia Cham. Aiming its application as preservative in cosmetic preparationFreitas, Beatriz Resende 28 March 2008 (has links)
O potencial farmacológico de espécies do gênero Lippia no tratamento de infecções é conhecido popularmente, assim foi considerado o estudo da atividade da Lippia salviaefolia nativa do cerrado brasileiro. O objetivo do trabalho foi avaliar a atividade antimicrobiana de extratos de Lippia salviaefolia Cham. e sua citotoxicidade, visando aplicação como conservante natural em formulações cosméticas. O ensaio antimicrobiano foi realizado através do método de difusão em placa e determinação do CMI por de microdiluição em microplacas, utilizando os microrganismos: P. aeruginosa ATCC 9027, S. aureus ATCC 6538, E. coli ATCC 8739, C. albicans ATCC 10231. Desenvolveu-se e avaliou-se a estabilidade acelerada de cremes, geis e xampus contendo o extrato de Lippia salviaefolia. As formulações de melhor desempenho quanto à estabilidade foram submetidas ao teste de eficácia de conservante. Avaliou-se segurança das formulações in vitro, em substituto cutâneo dermo-epidérmico por meio de estudos histológicos e o teste de citotoxicidade em cultura de queratinócitos humanos. No teste de atividade antimicrobiana verificou-se que a fração de acetato de etila e a fração de clorofórmio foram frações mais ativas com CMI de 0,2 % para bactérias e fungos. Os testes de eficácia de conservante das formulações contendo fr. ac. etila de L. salviaefolia apresentaram atividade antimicrobiana para bactérias e C. albicans em creme, gel e xampu, para A. niger apresentaram atividade adequada somente em xampu. No teste de citoxicidade foi verificado segurança em concentrações a partir de 0,05 %. Sendo que na concentração de 0,2 %, correspondente ao CMI, se atinge a faixa de segurança apenas com meia hora de contato. Os resultados sugerem que a fração de acetato de etila da Lippia salviaefolia Cham. pode ser utilizada como conservante natural em produtos cosméticos. / The pharmacological potential of species of the Lippia in the treatment of infections has been known popularly, thus was considered the study of the activity of the native salviaefolia Lippia of the Brazilian Cerrado. The purpose of the work was to evaluate the antimicrobial activity of extracts of Lippia salviaefolia Cham. and its citotoxicy aiming the application as natural preservative in cosmetic formulations. The assay antimicrobial was carried through the method of diffusion in plate and determination of the MIC by microdilution, having used the microorganisms: P.aeruginosa ATCC 9027, S. aureus ATCC 6538, E. coli ATCC 8739, C. albicans ATCC 10231. It has developed and evaluated the stability of creams, gels and xampus with the extract of Lippia salviaefolia Cham. The formulations of the best stability performance have submitted to preservative efficacy test. The safe of the formulations has histological evaluated by in vitro. In the test of antimicrobial activity it has verified that the ethyl acetate and the chloroform fraction have been the most active and with CMI of 0.2 % for bacteria and fungus. The tests of effectiveness of preservatives have showed of the formulations contend the ethyl acetate fraction presented antimicrobial activity for bacteria and C. albican in cream, gel and shampoo. On the other hand, against A.niger it has been suitable activity in shampoo. In the citotoxity test, the 0,05 % ethyl acetate fraction has presented interval of security. And in the concentration of 0,2%, corresponding to CMI, safety\'s strip is just reached with half hour of contact. The results have suggested that the ethyl acetate extract of the Lippia salviaefolia Cham. should be used as natural preservative in cosmetic products.
|
| 102 |
Xylophagous Insects: developments in feeding assaysPeters, Brenton Charles Unknown Date (has links)
Xylophagous borers and termites that damage "timber-in-service" cause millions of dollars loss annually throughout mainland Australia. I developed field-based feeding assays with practical relevance to preventative action and remedial treatment of infestations of xylophagous insects in the built environment. Essential to this work is facilitating a high termite risk by maintaining an environment conducive to sustained foraging by termites. Feeding assays conducted in low termite risk areas are unduly prolonged, with inherently erratic termite feeding responses. I successfully developed feeding assays with a high termite risk. To establish whether a physical barrier, retrofitted as a sleeve, could prevent termites from damaging wooden poles, eighty poles were established within Beerburrum State Forest, south-east Queensland, Australia. Poles within sets were interconnected with buried timber to facilitate a high risk to Coptotermes acinaciformis (Froggatt). Mesh sleeves to a depth of 1.5m did not prevent termite damage to the poles. Hoop pine Araucaria cunninghamii Ait. ex D.Don dowels ("dip-sticks") were useful termite monitoring devices on the poles. The depth of foraging by termites has implications for the effectiveness of retrofitted physical and chemical barriers in general. Timber quantity and quality has a pivotal influence on the aggregation of large numbers of feeding termites necessary for baiting work and for producing efficacy data of relevance to the protection of timber-in-service from termites. Seasonal variation in termite foraging was examined. Both C. acinaciformis and Coptotermes lacteus (Froggatt) were more active feeding in summer than in autumn. In general, mass loss followed mean ambient temperature. Suppression of C. acinaciformis feeding responses relative to C. lacteus during summer, particularly during January, is thought to be due to excessive temperatures in the containers attached to infested trees. Termite foraging behaviour and responses to both varying masses of softwood timbers and varying exposure times were investigated. The rate of mass loss was independent of the number of test specimens and appeared linear. Colonies regulate the number of foragers directly according to the mass of susceptible timber available. This phenomenon was exploited throughout the remainder of the thesis. Of particular significance was the considerable intra- and inter-specific variation in susceptibility of softwoods to C. acinaciformis and Mastotermes darwiniensis Froggatt. The sapwoods tested were susceptible, but the heartwoods were generally resistant to damage by termites. These data confirm that termites are discriminating feeders, and some more so than others. A novel methodology, developed to maintain an environment conducive to sustained foraging by termites during field-testing, is presented. Consistency in timber acceptance and susceptibility to termites is considered to be important in determining the frequency of inspection and the success of bait systems. I evaluate the termiticidal activity of the bait toxicants hexaflumuron and chlorfluazuron for the management of the subterranean termite C. acinaciformis in the field. The Sentricon Colony Elimination System with Baitube-devices containing 0.1% and 1% mass/mass (m/m) hexaflumuron bait toxicant in dry wood flour (Recruit) was successful in eliminating field colonies of C. acinaciformis. Similarly, the Exterra Termite Interception and Baiting System with cellulose-acetate powder containing either 0.05% m/m or 0.25% m/m chlorfluazuron (Requiem) eliminated C. acinaciformis. Indicators (including "dip-sticks") used to monitor colony health were reliable. By using C. acinaciformis, which builds mounds (epigeous nests) in northern Australia, I was able to avoid the use of multiple mark-release schemes to verify the effects of the bait toxicant on the termite colonies. Problems with multiple mark-release schemes, used elsewhere in the world, are discussed. I continued the focus on bait quality and placement by evaluating termite responses to two aspects of treated stakes, their attractiveness and their susceptibility. Three experiments were undertaken near Townsville and at Beerburrum, with Coptotermes and Schedorhinotermes. Whilst there were no significant differences in the rate of location and foraging, with respect to treatments, differences in foraging, with respect to C. acinaciformis and Schedorhinotermes seclusus (Hill) were significant. Coptotermes acinaciformis displayed greater foraging site tenacity than S. seclusus at Beerburrum. Increased consumption of bait, due to the addition of a phagostimulant, needs to be observed in the field before an increase in the efficacy of baits in a termite management program can be claimed. In Australia, softwood timbers are extensively used in building construction and are generally highly susceptible to damage by termites. I focussed on field feeding assays to test efficacy of borate-treated softwoods against termites and to define "adequate" protection thresholds. Laboratory and field data reported in the literature were confusing with regard to what constitutes "adequate" protection thresholds. The confusion was compounded by differences in termite species, timber species used and test methodology. Laboratory data indicated a borate loading of 0.5% m/m boric acid equivalent (BAE) would cause > 90% termite mortality and restrict mass loss in test specimens to 5%. Field data generally suggested that borate loadings in excess of 0.5% m/m BAE were required. The main contribution of the work to increasing our understanding of management options for termites in the built environment was in resolving the confusion between laboratory and field data for borate wood-preservatives. These apparently conflicting results were explained by the presence or absence of untreated feeder material in the test environment. In the absence of untreated feeder material, retention of 0.5% BAE provides adequate protection from Coptotermes sp., whereas in the presence of untreated feeder material, increased retentions are required. Furthermore, the retentions required increase with increased amounts of susceptible material. Some termites, Nasutitermes sp. and M. darwiniensis, for example, are borate-tolerant and borate wood-preservatives are not a viable management option. The lack of uniform standards for termite-test methodology and assessment criteria for efficacy across the world is recognized as a difficulty with research into the performance of wood preservatives with termites. The many variables in laboratory and field assays make "prescriptive" standards difficult to recommend. The use of "performance" standards to define efficacy criteria ("adequate" protection) is discussed. Whilst the majority of the work involves subterranean termites ("termites"), I examine the question of how to define a hardwood timber species as "not susceptible" to lyctine beetle damage. Aspects of the biology, behaviour and management of Lyctus brunneus (Stephens) are reviewed and a novel field sampling and testing protocol to establish lyctine susceptibility of timber species is presented. A sound understanding of the biology and behaviour of xylophagous insects in the field is essential to ensure that management options implemented in the built environment have a strong ecological basis. The success of this study in achieving stated aims, the need for further work and the implications for test methodologies in the field with practical relevance to infestations of xylophagous insects in the built environment are discussed.
|
| 103 |
Xylophagous Insects: developments in feeding assaysPeters, Brenton Charles Unknown Date (has links)
Xylophagous borers and termites that damage "timber-in-service" cause millions of dollars loss annually throughout mainland Australia. I developed field-based feeding assays with practical relevance to preventative action and remedial treatment of infestations of xylophagous insects in the built environment. Essential to this work is facilitating a high termite risk by maintaining an environment conducive to sustained foraging by termites. Feeding assays conducted in low termite risk areas are unduly prolonged, with inherently erratic termite feeding responses. I successfully developed feeding assays with a high termite risk. To establish whether a physical barrier, retrofitted as a sleeve, could prevent termites from damaging wooden poles, eighty poles were established within Beerburrum State Forest, south-east Queensland, Australia. Poles within sets were interconnected with buried timber to facilitate a high risk to Coptotermes acinaciformis (Froggatt). Mesh sleeves to a depth of 1.5m did not prevent termite damage to the poles. Hoop pine Araucaria cunninghamii Ait. ex D.Don dowels ("dip-sticks") were useful termite monitoring devices on the poles. The depth of foraging by termites has implications for the effectiveness of retrofitted physical and chemical barriers in general. Timber quantity and quality has a pivotal influence on the aggregation of large numbers of feeding termites necessary for baiting work and for producing efficacy data of relevance to the protection of timber-in-service from termites. Seasonal variation in termite foraging was examined. Both C. acinaciformis and Coptotermes lacteus (Froggatt) were more active feeding in summer than in autumn. In general, mass loss followed mean ambient temperature. Suppression of C. acinaciformis feeding responses relative to C. lacteus during summer, particularly during January, is thought to be due to excessive temperatures in the containers attached to infested trees. Termite foraging behaviour and responses to both varying masses of softwood timbers and varying exposure times were investigated. The rate of mass loss was independent of the number of test specimens and appeared linear. Colonies regulate the number of foragers directly according to the mass of susceptible timber available. This phenomenon was exploited throughout the remainder of the thesis. Of particular significance was the considerable intra- and inter-specific variation in susceptibility of softwoods to C. acinaciformis and Mastotermes darwiniensis Froggatt. The sapwoods tested were susceptible, but the heartwoods were generally resistant to damage by termites. These data confirm that termites are discriminating feeders, and some more so than others. A novel methodology, developed to maintain an environment conducive to sustained foraging by termites during field-testing, is presented. Consistency in timber acceptance and susceptibility to termites is considered to be important in determining the frequency of inspection and the success of bait systems. I evaluate the termiticidal activity of the bait toxicants hexaflumuron and chlorfluazuron for the management of the subterranean termite C. acinaciformis in the field. The Sentricon Colony Elimination System with Baitube-devices containing 0.1% and 1% mass/mass (m/m) hexaflumuron bait toxicant in dry wood flour (Recruit) was successful in eliminating field colonies of C. acinaciformis. Similarly, the Exterra Termite Interception and Baiting System with cellulose-acetate powder containing either 0.05% m/m or 0.25% m/m chlorfluazuron (Requiem) eliminated C. acinaciformis. Indicators (including "dip-sticks") used to monitor colony health were reliable. By using C. acinaciformis, which builds mounds (epigeous nests) in northern Australia, I was able to avoid the use of multiple mark-release schemes to verify the effects of the bait toxicant on the termite colonies. Problems with multiple mark-release schemes, used elsewhere in the world, are discussed. I continued the focus on bait quality and placement by evaluating termite responses to two aspects of treated stakes, their attractiveness and their susceptibility. Three experiments were undertaken near Townsville and at Beerburrum, with Coptotermes and Schedorhinotermes. Whilst there were no significant differences in the rate of location and foraging, with respect to treatments, differences in foraging, with respect to C. acinaciformis and Schedorhinotermes seclusus (Hill) were significant. Coptotermes acinaciformis displayed greater foraging site tenacity than S. seclusus at Beerburrum. Increased consumption of bait, due to the addition of a phagostimulant, needs to be observed in the field before an increase in the efficacy of baits in a termite management program can be claimed. In Australia, softwood timbers are extensively used in building construction and are generally highly susceptible to damage by termites. I focussed on field feeding assays to test efficacy of borate-treated softwoods against termites and to define "adequate" protection thresholds. Laboratory and field data reported in the literature were confusing with regard to what constitutes "adequate" protection thresholds. The confusion was compounded by differences in termite species, timber species used and test methodology. Laboratory data indicated a borate loading of 0.5% m/m boric acid equivalent (BAE) would cause > 90% termite mortality and restrict mass loss in test specimens to 5%. Field data generally suggested that borate loadings in excess of 0.5% m/m BAE were required. The main contribution of the work to increasing our understanding of management options for termites in the built environment was in resolving the confusion between laboratory and field data for borate wood-preservatives. These apparently conflicting results were explained by the presence or absence of untreated feeder material in the test environment. In the absence of untreated feeder material, retention of 0.5% BAE provides adequate protection from Coptotermes sp., whereas in the presence of untreated feeder material, increased retentions are required. Furthermore, the retentions required increase with increased amounts of susceptible material. Some termites, Nasutitermes sp. and M. darwiniensis, for example, are borate-tolerant and borate wood-preservatives are not a viable management option. The lack of uniform standards for termite-test methodology and assessment criteria for efficacy across the world is recognized as a difficulty with research into the performance of wood preservatives with termites. The many variables in laboratory and field assays make "prescriptive" standards difficult to recommend. The use of "performance" standards to define efficacy criteria ("adequate" protection) is discussed. Whilst the majority of the work involves subterranean termites ("termites"), I examine the question of how to define a hardwood timber species as "not susceptible" to lyctine beetle damage. Aspects of the biology, behaviour and management of Lyctus brunneus (Stephens) are reviewed and a novel field sampling and testing protocol to establish lyctine susceptibility of timber species is presented. A sound understanding of the biology and behaviour of xylophagous insects in the field is essential to ensure that management options implemented in the built environment have a strong ecological basis. The success of this study in achieving stated aims, the need for further work and the implications for test methodologies in the field with practical relevance to infestations of xylophagous insects in the built environment are discussed.
|
| 104 |
Xylophagous Insects: developments in feeding assaysPeters, Brenton Charles Unknown Date (has links)
Xylophagous borers and termites that damage "timber-in-service" cause millions of dollars loss annually throughout mainland Australia. I developed field-based feeding assays with practical relevance to preventative action and remedial treatment of infestations of xylophagous insects in the built environment. Essential to this work is facilitating a high termite risk by maintaining an environment conducive to sustained foraging by termites. Feeding assays conducted in low termite risk areas are unduly prolonged, with inherently erratic termite feeding responses. I successfully developed feeding assays with a high termite risk. To establish whether a physical barrier, retrofitted as a sleeve, could prevent termites from damaging wooden poles, eighty poles were established within Beerburrum State Forest, south-east Queensland, Australia. Poles within sets were interconnected with buried timber to facilitate a high risk to Coptotermes acinaciformis (Froggatt). Mesh sleeves to a depth of 1.5m did not prevent termite damage to the poles. Hoop pine Araucaria cunninghamii Ait. ex D.Don dowels ("dip-sticks") were useful termite monitoring devices on the poles. The depth of foraging by termites has implications for the effectiveness of retrofitted physical and chemical barriers in general. Timber quantity and quality has a pivotal influence on the aggregation of large numbers of feeding termites necessary for baiting work and for producing efficacy data of relevance to the protection of timber-in-service from termites. Seasonal variation in termite foraging was examined. Both C. acinaciformis and Coptotermes lacteus (Froggatt) were more active feeding in summer than in autumn. In general, mass loss followed mean ambient temperature. Suppression of C. acinaciformis feeding responses relative to C. lacteus during summer, particularly during January, is thought to be due to excessive temperatures in the containers attached to infested trees. Termite foraging behaviour and responses to both varying masses of softwood timbers and varying exposure times were investigated. The rate of mass loss was independent of the number of test specimens and appeared linear. Colonies regulate the number of foragers directly according to the mass of susceptible timber available. This phenomenon was exploited throughout the remainder of the thesis. Of particular significance was the considerable intra- and inter-specific variation in susceptibility of softwoods to C. acinaciformis and Mastotermes darwiniensis Froggatt. The sapwoods tested were susceptible, but the heartwoods were generally resistant to damage by termites. These data confirm that termites are discriminating feeders, and some more so than others. A novel methodology, developed to maintain an environment conducive to sustained foraging by termites during field-testing, is presented. Consistency in timber acceptance and susceptibility to termites is considered to be important in determining the frequency of inspection and the success of bait systems. I evaluate the termiticidal activity of the bait toxicants hexaflumuron and chlorfluazuron for the management of the subterranean termite C. acinaciformis in the field. The Sentricon Colony Elimination System with Baitube-devices containing 0.1% and 1% mass/mass (m/m) hexaflumuron bait toxicant in dry wood flour (Recruit) was successful in eliminating field colonies of C. acinaciformis. Similarly, the Exterra Termite Interception and Baiting System with cellulose-acetate powder containing either 0.05% m/m or 0.25% m/m chlorfluazuron (Requiem) eliminated C. acinaciformis. Indicators (including "dip-sticks") used to monitor colony health were reliable. By using C. acinaciformis, which builds mounds (epigeous nests) in northern Australia, I was able to avoid the use of multiple mark-release schemes to verify the effects of the bait toxicant on the termite colonies. Problems with multiple mark-release schemes, used elsewhere in the world, are discussed. I continued the focus on bait quality and placement by evaluating termite responses to two aspects of treated stakes, their attractiveness and their susceptibility. Three experiments were undertaken near Townsville and at Beerburrum, with Coptotermes and Schedorhinotermes. Whilst there were no significant differences in the rate of location and foraging, with respect to treatments, differences in foraging, with respect to C. acinaciformis and Schedorhinotermes seclusus (Hill) were significant. Coptotermes acinaciformis displayed greater foraging site tenacity than S. seclusus at Beerburrum. Increased consumption of bait, due to the addition of a phagostimulant, needs to be observed in the field before an increase in the efficacy of baits in a termite management program can be claimed. In Australia, softwood timbers are extensively used in building construction and are generally highly susceptible to damage by termites. I focussed on field feeding assays to test efficacy of borate-treated softwoods against termites and to define "adequate" protection thresholds. Laboratory and field data reported in the literature were confusing with regard to what constitutes "adequate" protection thresholds. The confusion was compounded by differences in termite species, timber species used and test methodology. Laboratory data indicated a borate loading of 0.5% m/m boric acid equivalent (BAE) would cause > 90% termite mortality and restrict mass loss in test specimens to 5%. Field data generally suggested that borate loadings in excess of 0.5% m/m BAE were required. The main contribution of the work to increasing our understanding of management options for termites in the built environment was in resolving the confusion between laboratory and field data for borate wood-preservatives. These apparently conflicting results were explained by the presence or absence of untreated feeder material in the test environment. In the absence of untreated feeder material, retention of 0.5% BAE provides adequate protection from Coptotermes sp., whereas in the presence of untreated feeder material, increased retentions are required. Furthermore, the retentions required increase with increased amounts of susceptible material. Some termites, Nasutitermes sp. and M. darwiniensis, for example, are borate-tolerant and borate wood-preservatives are not a viable management option. The lack of uniform standards for termite-test methodology and assessment criteria for efficacy across the world is recognized as a difficulty with research into the performance of wood preservatives with termites. The many variables in laboratory and field assays make "prescriptive" standards difficult to recommend. The use of "performance" standards to define efficacy criteria ("adequate" protection) is discussed. Whilst the majority of the work involves subterranean termites ("termites"), I examine the question of how to define a hardwood timber species as "not susceptible" to lyctine beetle damage. Aspects of the biology, behaviour and management of Lyctus brunneus (Stephens) are reviewed and a novel field sampling and testing protocol to establish lyctine susceptibility of timber species is presented. A sound understanding of the biology and behaviour of xylophagous insects in the field is essential to ensure that management options implemented in the built environment have a strong ecological basis. The success of this study in achieving stated aims, the need for further work and the implications for test methodologies in the field with practical relevance to infestations of xylophagous insects in the built environment are discussed.
|
| 105 |
Xylophagous Insects: developments in feeding assaysPeters, Brenton Charles Unknown Date (has links)
Xylophagous borers and termites that damage "timber-in-service" cause millions of dollars loss annually throughout mainland Australia. I developed field-based feeding assays with practical relevance to preventative action and remedial treatment of infestations of xylophagous insects in the built environment. Essential to this work is facilitating a high termite risk by maintaining an environment conducive to sustained foraging by termites. Feeding assays conducted in low termite risk areas are unduly prolonged, with inherently erratic termite feeding responses. I successfully developed feeding assays with a high termite risk. To establish whether a physical barrier, retrofitted as a sleeve, could prevent termites from damaging wooden poles, eighty poles were established within Beerburrum State Forest, south-east Queensland, Australia. Poles within sets were interconnected with buried timber to facilitate a high risk to Coptotermes acinaciformis (Froggatt). Mesh sleeves to a depth of 1.5m did not prevent termite damage to the poles. Hoop pine Araucaria cunninghamii Ait. ex D.Don dowels ("dip-sticks") were useful termite monitoring devices on the poles. The depth of foraging by termites has implications for the effectiveness of retrofitted physical and chemical barriers in general. Timber quantity and quality has a pivotal influence on the aggregation of large numbers of feeding termites necessary for baiting work and for producing efficacy data of relevance to the protection of timber-in-service from termites. Seasonal variation in termite foraging was examined. Both C. acinaciformis and Coptotermes lacteus (Froggatt) were more active feeding in summer than in autumn. In general, mass loss followed mean ambient temperature. Suppression of C. acinaciformis feeding responses relative to C. lacteus during summer, particularly during January, is thought to be due to excessive temperatures in the containers attached to infested trees. Termite foraging behaviour and responses to both varying masses of softwood timbers and varying exposure times were investigated. The rate of mass loss was independent of the number of test specimens and appeared linear. Colonies regulate the number of foragers directly according to the mass of susceptible timber available. This phenomenon was exploited throughout the remainder of the thesis. Of particular significance was the considerable intra- and inter-specific variation in susceptibility of softwoods to C. acinaciformis and Mastotermes darwiniensis Froggatt. The sapwoods tested were susceptible, but the heartwoods were generally resistant to damage by termites. These data confirm that termites are discriminating feeders, and some more so than others. A novel methodology, developed to maintain an environment conducive to sustained foraging by termites during field-testing, is presented. Consistency in timber acceptance and susceptibility to termites is considered to be important in determining the frequency of inspection and the success of bait systems. I evaluate the termiticidal activity of the bait toxicants hexaflumuron and chlorfluazuron for the management of the subterranean termite C. acinaciformis in the field. The Sentricon Colony Elimination System with Baitube-devices containing 0.1% and 1% mass/mass (m/m) hexaflumuron bait toxicant in dry wood flour (Recruit) was successful in eliminating field colonies of C. acinaciformis. Similarly, the Exterra Termite Interception and Baiting System with cellulose-acetate powder containing either 0.05% m/m or 0.25% m/m chlorfluazuron (Requiem) eliminated C. acinaciformis. Indicators (including "dip-sticks") used to monitor colony health were reliable. By using C. acinaciformis, which builds mounds (epigeous nests) in northern Australia, I was able to avoid the use of multiple mark-release schemes to verify the effects of the bait toxicant on the termite colonies. Problems with multiple mark-release schemes, used elsewhere in the world, are discussed. I continued the focus on bait quality and placement by evaluating termite responses to two aspects of treated stakes, their attractiveness and their susceptibility. Three experiments were undertaken near Townsville and at Beerburrum, with Coptotermes and Schedorhinotermes. Whilst there were no significant differences in the rate of location and foraging, with respect to treatments, differences in foraging, with respect to C. acinaciformis and Schedorhinotermes seclusus (Hill) were significant. Coptotermes acinaciformis displayed greater foraging site tenacity than S. seclusus at Beerburrum. Increased consumption of bait, due to the addition of a phagostimulant, needs to be observed in the field before an increase in the efficacy of baits in a termite management program can be claimed. In Australia, softwood timbers are extensively used in building construction and are generally highly susceptible to damage by termites. I focussed on field feeding assays to test efficacy of borate-treated softwoods against termites and to define "adequate" protection thresholds. Laboratory and field data reported in the literature were confusing with regard to what constitutes "adequate" protection thresholds. The confusion was compounded by differences in termite species, timber species used and test methodology. Laboratory data indicated a borate loading of 0.5% m/m boric acid equivalent (BAE) would cause > 90% termite mortality and restrict mass loss in test specimens to 5%. Field data generally suggested that borate loadings in excess of 0.5% m/m BAE were required. The main contribution of the work to increasing our understanding of management options for termites in the built environment was in resolving the confusion between laboratory and field data for borate wood-preservatives. These apparently conflicting results were explained by the presence or absence of untreated feeder material in the test environment. In the absence of untreated feeder material, retention of 0.5% BAE provides adequate protection from Coptotermes sp., whereas in the presence of untreated feeder material, increased retentions are required. Furthermore, the retentions required increase with increased amounts of susceptible material. Some termites, Nasutitermes sp. and M. darwiniensis, for example, are borate-tolerant and borate wood-preservatives are not a viable management option. The lack of uniform standards for termite-test methodology and assessment criteria for efficacy across the world is recognized as a difficulty with research into the performance of wood preservatives with termites. The many variables in laboratory and field assays make "prescriptive" standards difficult to recommend. The use of "performance" standards to define efficacy criteria ("adequate" protection) is discussed. Whilst the majority of the work involves subterranean termites ("termites"), I examine the question of how to define a hardwood timber species as "not susceptible" to lyctine beetle damage. Aspects of the biology, behaviour and management of Lyctus brunneus (Stephens) are reviewed and a novel field sampling and testing protocol to establish lyctine susceptibility of timber species is presented. A sound understanding of the biology and behaviour of xylophagous insects in the field is essential to ensure that management options implemented in the built environment have a strong ecological basis. The success of this study in achieving stated aims, the need for further work and the implications for test methodologies in the field with practical relevance to infestations of xylophagous insects in the built environment are discussed.
|
| 106 |
Determination of the optimal preservatives for preventing stem bending of Gebera jamesonii "Black Diamond"Maluleke, Mdungazi Knox 10 1900 (has links)
Postharvest stem bending is one of the most detrimental factors that affect postharvest quality life of Gerbera jamesonii cutflower varieties. Stem bending is of economic importance in the cutflower industry in South Africa because it negatively affects the overall total sales. Growers and retailers want to improve the postharvest vaselife of this crop using suitable preservatives. The aim of this study was to determine suitable preservatives and optimal vaselife conditions that could prevent or minimise postharvest stem bending of Gerbera jamesonii “Black diamond”.
The variety “Black diamond was selected and treated with four different floral preservative solutions. The relationship between stem bending and absorption rate of the preservative solutions was established. The data gathered indicated that there was a significant difference to the solution absorption rate and stem bending. Stem bending differed from 0 to 38 degrees. Stems treated on control, preservative 3 and 4 recorded the highest degrees of bending, while preservative 1 and 2 recorded the lowest degrees of stem bending within 12 day period. The performance results of the preservatives and control repeated three times under the same experimental conditions showed that preservative 1 and 2 can be used to minimise postharvest stem bending of Gerbera jamesonii ‘Black diamond’ / College of Agriculture and Environmental Sciences / M. Sc. (Ornamental Horticulture)
|
| 107 |
Avaliação da atividade antimicrobiana de extratos de folhas de Lippia salviaefolia Cham. visando sua aplicação como conservante em preparações cosméticas / Evaluation of the antimicrobial activity of leaf extracts of Lippia salviaefolia Cham. Aiming its application as preservative in cosmetic preparationBeatriz Resende Freitas 28 March 2008 (has links)
O potencial farmacológico de espécies do gênero Lippia no tratamento de infecções é conhecido popularmente, assim foi considerado o estudo da atividade da Lippia salviaefolia nativa do cerrado brasileiro. O objetivo do trabalho foi avaliar a atividade antimicrobiana de extratos de Lippia salviaefolia Cham. e sua citotoxicidade, visando aplicação como conservante natural em formulações cosméticas. O ensaio antimicrobiano foi realizado através do método de difusão em placa e determinação do CMI por de microdiluição em microplacas, utilizando os microrganismos: P. aeruginosa ATCC 9027, S. aureus ATCC 6538, E. coli ATCC 8739, C. albicans ATCC 10231. Desenvolveu-se e avaliou-se a estabilidade acelerada de cremes, geis e xampus contendo o extrato de Lippia salviaefolia. As formulações de melhor desempenho quanto à estabilidade foram submetidas ao teste de eficácia de conservante. Avaliou-se segurança das formulações in vitro, em substituto cutâneo dermo-epidérmico por meio de estudos histológicos e o teste de citotoxicidade em cultura de queratinócitos humanos. No teste de atividade antimicrobiana verificou-se que a fração de acetato de etila e a fração de clorofórmio foram frações mais ativas com CMI de 0,2 % para bactérias e fungos. Os testes de eficácia de conservante das formulações contendo fr. ac. etila de L. salviaefolia apresentaram atividade antimicrobiana para bactérias e C. albicans em creme, gel e xampu, para A. niger apresentaram atividade adequada somente em xampu. No teste de citoxicidade foi verificado segurança em concentrações a partir de 0,05 %. Sendo que na concentração de 0,2 %, correspondente ao CMI, se atinge a faixa de segurança apenas com meia hora de contato. Os resultados sugerem que a fração de acetato de etila da Lippia salviaefolia Cham. pode ser utilizada como conservante natural em produtos cosméticos. / The pharmacological potential of species of the Lippia in the treatment of infections has been known popularly, thus was considered the study of the activity of the native salviaefolia Lippia of the Brazilian Cerrado. The purpose of the work was to evaluate the antimicrobial activity of extracts of Lippia salviaefolia Cham. and its citotoxicy aiming the application as natural preservative in cosmetic formulations. The assay antimicrobial was carried through the method of diffusion in plate and determination of the MIC by microdilution, having used the microorganisms: P.aeruginosa ATCC 9027, S. aureus ATCC 6538, E. coli ATCC 8739, C. albicans ATCC 10231. It has developed and evaluated the stability of creams, gels and xampus with the extract of Lippia salviaefolia Cham. The formulations of the best stability performance have submitted to preservative efficacy test. The safe of the formulations has histological evaluated by in vitro. In the test of antimicrobial activity it has verified that the ethyl acetate and the chloroform fraction have been the most active and with CMI of 0.2 % for bacteria and fungus. The tests of effectiveness of preservatives have showed of the formulations contend the ethyl acetate fraction presented antimicrobial activity for bacteria and C. albican in cream, gel and shampoo. On the other hand, against A.niger it has been suitable activity in shampoo. In the citotoxity test, the 0,05 % ethyl acetate fraction has presented interval of security. And in the concentration of 0,2%, corresponding to CMI, safety\'s strip is just reached with half hour of contact. The results have suggested that the ethyl acetate extract of the Lippia salviaefolia Cham. should be used as natural preservative in cosmetic products.
|
| 108 |
Recherche de molécules antimicrobiennes d'origine lichénique : Etude phytochimique de trois lichens & approche synthétique de deux composés actifs / Research of antimicrobial molecules from lichens : Phytochemical study of three lichens and synthetic approach of two active compoundsAndraud-Dieu, Amandine 01 June 2015 (has links)
L’étude physicochimique de trois lichens récoltés en Limousin, Usnea florida, Flavoparmelia caperata et Cladonia incrassata, a permis d’isoler et de caractériser 16 composés issus du métabolisme secondaire. Dans un premier temps, ces lichens ont été sélectionnés lors d’un criblage analytique préliminaire réalisé sur 17 espèces. L’activité antimicrobienne des extraits acétoniques a été évaluée, puis leur fractionnement bioguidé a été mis en œuvre. Les deux isomères de l’acide usnique, 3 dibenzofuranes, 4 depsides, 3 depsidones, un acide aliphatique, un phtalide et un stérol ont été isolés. Une xanthone trichlorée, la cladoxanthone A, a été extraite et identifiée pour la première fois à partir d’une source naturelle. L’effet de tous les composés a été évalué sur Staphyloccocus aureus par bioautographie. Pour les produits isolés en quantité suffisante, des tests de dilution en milieu liquide ont permis de déterminer leurs CMI, en comparaison avec le Phénonip®, conservateur couramment utilisé dans l’industrie cosmétique. Les acides didymique et condidymique en particulier s’avèrent être de bons candidats pour une utilisation en tant que conservateurs. Dans un second temps, compte tenu de leur potentielle application industrielle, nous avons exploré des voies de synthèse de l’acide usnique et de la cladoxanthone A. Ainsi, la préparation de l’intermédiaire clé pour l’accès à l’acide usnique a été optimisée et les premiers essais de couplage en présence d’une porphyrine sont encourageants. De même, les voies de synthèse proposées et mises en œuvre pour la cladoxanthone A sont prometteuses. / Phytochemical study of three lichens collected in Limousin, Usnea florida, Flavoparmelia caperata and Cladonia incrassata, led to the isolation and the structural identification of 16 secondary metabolites. First, these lichens were chosen after a preliminary screening performed on 17 species. Antimicrobial activity of acetone extracts was evaluated and bioassay-guided fractionation was performed. The two isomers of usnic acid, 3 dibenzofurans, 4 depsides, 3 depsidones, one aliphatic acid and one sterol were isolated. A trichlorinated xanthone, named cladoxanthone A, was extracted and identified for the first time in a natural source. A bioautographic protocol was used to evaluate antibacterial activities of these compounds on Staphylococcus aureus. MICs of the products obtained in sufficient amounts were determined by a broth microdilution method in parallel with Phenonip®, a preservative commonly used in cosmetic industry. Didymic and condidymic acids were found to be good candidates for use as preservatives. Secondly, owing to their potential industrial application, we explored synthetic routes for usnic acid and cladoxanthone A. Thus, the preparation of the key intermediate for access to usnic acid was optimized and the first coupling tests in the presence of a porphyrin were encouraging. Similarly, the proposed synthetic routes for cladoxanthone A are promising.
|
| 109 |
Stanovení sladidel a konzervantů v energetických nápojích metodou HPLC / Determination of sweeteners and preservatives in energy drinks by HPLCZídková, Anežka January 2019 (has links)
This master´s thesis is focused on simultaneous determination of sweeteners and preservatives in energy drinks by liquid chromatography coupled with DAD and ELSD detection. The method was optimized for determination of aspartame, acesulfame K, saccharin, sucralose, steviol glycosides, benzoic acid and sorbic acid. Analyses were carried out on the Poroshell 120 EC-C18 column (4.6 x 150 mm, 2.7 m, Agilent) using mixture of methanol, acetone and water with formic acid and trimethylamine as a gradient mobile phase at a flow rate 0,5 mL•min-1. Validation parameters were determined (limit of detection, limit of quantification, repeatability and recovery). The validated method was applied on real samples.
|
| 110 |
Development of Sensitive In Vitro Assays to Assess the Ocular Toxicity Potential of Chemicals and Ophthalmic ProductsMcCanna, David January 2009 (has links)
The utilization of in vitro tests with a tiered testing strategy for detection of mild ocular irritants can reduce the use of animals for testing, provide mechanistic data on toxic effects, and reduce the uncertainty associated with dose selection for clinical trials. The first section of this thesis describes how in vitro methods can be used to improve the prediction of the toxicity of chemicals and ophthalmic products. The proper utilization of in vitro methods can accurately predict toxic threshold levels and reduce animal use in product development. Sections two, three and four describe the development of new sensitive in vitro methods for predicting ocular toxicity. Maintaining the barrier function of the cornea is critical for the prevention of the penetration of infections microorganisms and irritating chemicals into the eye. Chapter 2 describes the development of a method for assessing the effects of chemicals on tight junctions using a human corneal epithelial and canine kidney epithelial cell line. In Chapter 3 a method that uses a primary organ culture for assessing single instillation and multiple instillation toxic effects is described. The ScanTox system was shown to be an ideal system to monitor the toxic effects over time as multiple readings can be taken of treated bovine lenses using the nondestructive method of assessing for the lens optical quality. Confirmations of toxic effects were made with the utilization of the viability dye alamarBlue. Chapter 4 describes the development of sensitive in vitro assays for detecting ocular toxicity by measuring the effects of chemicals on the mitochondrial integrity of bovine cornea, bovine lens epithelium and corneal epithelial cells, using fluorescent dyes.
The goal of this research was to develop an in vitro test battery that can be used to accurately predict the ocular toxicity of new chemicals and ophthalmic formulations. By comparing the toxicity seen in vivo animals and humans with the toxicity response in these new in vitro methods, it was demonstrated that these in vitro methods can be utilized in a tiered testing strategy in the development of new chemicals and ophthalmic formulations.
|
Page generated in 0.0814 seconds