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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.
1

Investigations into Lead (Pb) Accumulation in Symphytum officinale L.: A Phytoremediation Study

Chin, Lily January 2007 (has links)
Lead (Pb) is the number one heavy metal pollutant in the environment. The high cost and environmental concerns of conventional remediation technologies has led to an emerging alternative technology for heavy metal remediation: phytoremediation. This study was set out to advance Pb phytoremediation by investigating plant-associated factors (e.g. polyphenol levels, Pb-tannin chelation, and superoxide dismutase activity) and chemical-based factors (e.g. concentration of Pb, and the type and dosage of chelating agents in treatments) that may affect Pb accumulation. Using a hydroponic system, sand-grown Symphytum officinale L. plants were exposed to nutrient solutions with or without lead nitrate (Pb(NO₃)₂) and ethylenediamine tetraacetic acid (EDTA). Using flame atomic absorption spectroscopy (to measure Pb content) and bovine serum albumin-protein precipitation (to measure polyphenol and tannin levels), a significant in vivo correlation between tannin level and Pb accumulation level was observed in roots of plants exposed to all Pb treatments. Higher tannin containing-lateral roots accumulated significantly more Pb than lowertannin main roots. Transmission electron micrographs of unchelated Pb-treated plants supported these findings, whilst dialysis-based in vitro Pb-chelation studies with crude S. officinale root polyphenol extracts did not. The dialysis method was likely to be subject to fructan interference. A new, more accurate and simple method based on tannin immobilisation was consequently developed. Results using this method supported the hydroponic trends. This new method was also verified with purified tannic acid (from Sigma). Together, these findings demonstrate that S. officinale root tannins have the ability to chelate Pb. This may be a mechanism to cope with Pb stress (adaptive tolerance). Despite the typical signs of Pb stress at root level (e.g. root growth inhibition, and degraded cytoplasms), shoots showed no signs of stress under any Pb treatments. Most importantly, since this chelation-based tolerance mechanism also influences the accumulation levels, the phytochemical composition of plants should also be considered when screening plants for phytoremediation. The level of Pb accumulated in the shoots depended on the concentration of Pb(NO₃)₂ and presence of chelating agents (EDTA or N-[2 acetamido] iminodiacetic acid (ADA)) in the nutrient solution. The highest level of Pb in shoots was between 0.05-0.06% (d.w. on average) using EDTA or ADA, well short of the 1% (d.w.) shoot accumulation target for Pb phytoextraction. The highest level of Pb in the roots (and of all measurements) was with unchelated 500 µM Pb(NO₃)₂; on average 2% (d.w.) accumulated in root. Overall, since S. officinale accumulated Pb predominately in the roots, it is most suited for rhizofiltration and phytostabilisation. Whilst chelating agents enhanced Pb accumulation in shoots, root levels were unexpectedly reduced compared to unchelated Pb treatments. The level of Pb translocated did not completely account for this loss. Minor factors relating to EDTA desorption of roots, EDTA specificity, and charge repulsion of the PbEDTA complex may account for some of the loss, but the main cause remains unclear. In vitro S. officinale cultures were developed and somaclonal variation (involving Pb pre-treatment of petioles) was used as a tool to further investigate, and attempt to improve its Pb phytoremediation potential. The shoots and roots of plants produced from petioles pre-treated with Pb(NO₃)₂ appeared more stressed than those without Pb pre-treatment. After re-treatment with Pb (Pb(NO₃)₂ or PbADA), plants developed from most Pb pre-treated petioles appeared to have reduced Pb accumulation and polyphenol levels, and increased superoxide dismutase activity in roots (although no statistically significant trends were found). Overall, plants produced from Pb pre-treated petioles in this study may have less phytoremediation potential.
2

Untersuchungen über die Entwickelung der Inflorescenz und der Blüthen

Muth, Franz. January 1902 (has links)
Habilitationsschrift--Technische Hochschule, Karlsruhe. / Sonderabdruck aus "Flora oder Allgem. bot. Zeitung," Ergänzungsband 1902.
3

Gingerols and shogaols: Important nutraceutical principles from ginger

Semwal, RB, Combrick, S, Viljoen, M, Semwal, DK 19 August 2015 (has links)
Gingerols are the major pungent compounds present in the rhizomes of ginger (Zingiber officinale Roscoe) and are renowned for their contribution to human health and nutrition. Medicinal properties of ginger, including the alleviation of nausea, arthritis and pain, have been associated with the gingerols. Gingerol analogues are thermally labile and easily undergo dehydration reactions to form the corresponding shogaols, which impart the characteristic pungent taste to dried ginger. Both gingerols and shogaols exhibit a host of biological activities, ranging from anticancer, anti-oxidant, antimicrobial, anti-inflammatory and anti-allergic to various central nervous system activities. Shogaols are important biomarkers used for the quality control of many ginger-containing products, due to their diverse biological activities. In this review, a large body of available knowledge on the biosynthesis, chemical synthesis and pharmacological activities, as well as on the structure–activity relationships of various gingerols and shogaols, have been collated, coherently summarised and discussed. The manuscript highlights convincing evidence indicating that these phenolic compounds could serve as important lead molecules for the development of therapeutic agents to treat various life-threatening human diseases, particularly cancer. Inclusion of ginger or ginger extracts in nutraceutical formulations could provide valuable protection against diabetes, cardiac and hepatic disorders.
4

Investigations into Lead (Pb) Accumulation in Symphytum officinale L.: A Phytoremediation Study

Chin, Lily January 2007 (has links)
Lead (Pb) is the number one heavy metal pollutant in the environment. The high cost and environmental concerns of conventional remediation technologies has led to an emerging alternative technology for heavy metal remediation: phytoremediation. This study was set out to advance Pb phytoremediation by investigating plant-associated factors (e.g. polyphenol levels, Pb-tannin chelation, and superoxide dismutase activity) and chemical-based factors (e.g. concentration of Pb, and the type and dosage of chelating agents in treatments) that may affect Pb accumulation. Using a hydroponic system, sand-grown Symphytum officinale L. plants were exposed to nutrient solutions with or without lead nitrate (Pb(NO₃)₂) and ethylenediamine tetraacetic acid (EDTA). Using flame atomic absorption spectroscopy (to measure Pb content) and bovine serum albumin-protein precipitation (to measure polyphenol and tannin levels), a significant in vivo correlation between tannin level and Pb accumulation level was observed in roots of plants exposed to all Pb treatments. Higher tannin containing-lateral roots accumulated significantly more Pb than lowertannin main roots. Transmission electron micrographs of unchelated Pb-treated plants supported these findings, whilst dialysis-based in vitro Pb-chelation studies with crude S. officinale root polyphenol extracts did not. The dialysis method was likely to be subject to fructan interference. A new, more accurate and simple method based on tannin immobilisation was consequently developed. Results using this method supported the hydroponic trends. This new method was also verified with purified tannic acid (from Sigma). Together, these findings demonstrate that S. officinale root tannins have the ability to chelate Pb. This may be a mechanism to cope with Pb stress (adaptive tolerance). Despite the typical signs of Pb stress at root level (e.g. root growth inhibition, and degraded cytoplasms), shoots showed no signs of stress under any Pb treatments. Most importantly, since this chelation-based tolerance mechanism also influences the accumulation levels, the phytochemical composition of plants should also be considered when screening plants for phytoremediation. The level of Pb accumulated in the shoots depended on the concentration of Pb(NO₃)₂ and presence of chelating agents (EDTA or N-[2 acetamido] iminodiacetic acid (ADA)) in the nutrient solution. The highest level of Pb in shoots was between 0.05-0.06% (d.w. on average) using EDTA or ADA, well short of the 1% (d.w.) shoot accumulation target for Pb phytoextraction. The highest level of Pb in the roots (and of all measurements) was with unchelated 500 µM Pb(NO₃)₂; on average 2% (d.w.) accumulated in root. Overall, since S. officinale accumulated Pb predominately in the roots, it is most suited for rhizofiltration and phytostabilisation. Whilst chelating agents enhanced Pb accumulation in shoots, root levels were unexpectedly reduced compared to unchelated Pb treatments. The level of Pb translocated did not completely account for this loss. Minor factors relating to EDTA desorption of roots, EDTA specificity, and charge repulsion of the PbEDTA complex may account for some of the loss, but the main cause remains unclear. In vitro S. officinale cultures were developed and somaclonal variation (involving Pb pre-treatment of petioles) was used as a tool to further investigate, and attempt to improve its Pb phytoremediation potential. The shoots and roots of plants produced from petioles pre-treated with Pb(NO₃)₂ appeared more stressed than those without Pb pre-treatment. After re-treatment with Pb (Pb(NO₃)₂ or PbADA), plants developed from most Pb pre-treated petioles appeared to have reduced Pb accumulation and polyphenol levels, and increased superoxide dismutase activity in roots (although no statistically significant trends were found). Overall, plants produced from Pb pre-treated petioles in this study may have less phytoremediation potential.
5

Investigations into Lead (Pb) Accumulation in

Chin, Lily January 2007 (has links)
Lead (Pb) is the number one heavy metal pollutant in the environment. The high cost and environmental concerns of conventional remediation technologies has led to an emerging alternative technology for heavy metal remediation: phytoremediation. This study was set out to advance Pb phytoremediation by investigating plant-associated factors (e.g. polyphenol levels, Pb-tannin chelation, and superoxide dismutase activity) and chemical-based factors (e.g. concentration of Pb, and the type and dosage of chelating agents in treatments) that may affect Pb accumulation. Using a hydroponic system, sand-grown Symphytum officinale L. plants were exposed to nutrient solutions with or without lead nitrate (Pb(NO₃)₂) and ethylenediamine tetraacetic acid (EDTA). Using flame atomic absorption spectroscopy (to measure Pb content) and bovine serum albumin-protein precipitation (to measure polyphenol and tannin levels), a significant in vivo correlation between tannin level and Pb accumulation level was observed in roots of plants exposed to all Pb treatments. Higher tannin containing-lateral roots accumulated significantly more Pb than lowertannin main roots. Transmission electron micrographs of unchelated Pb-treated plants supported these findings, whilst dialysis-based in vitro Pb-chelation studies with crude S. officinale root polyphenol extracts did not. The dialysis method was likely to be subject to fructan interference. A new, more accurate and simple method based on tannin immobilisation was consequently developed. Results using this method supported the hydroponic trends. This new method was also verified with purified tannic acid (from Sigma). Together, these findings demonstrate that S. officinale root tannins have the ability to chelate Pb. This may be a mechanism to cope with Pb stress (adaptive tolerance). Despite the typical signs of Pb stress at root level (e.g. root growth inhibition, and degraded cytoplasms), shoots showed no signs of stress under any Pb treatments. Most importantly, since this chelation-based tolerance mechanism also influences the accumulation levels, the phytochemical composition of plants should also be considered when screening plants for phytoremediation. The level of Pb accumulated in the shoots depended on the concentration of Pb(NO₃)₂ and presence of chelating agents (EDTA or N-[2 acetamido] iminodiacetic acid (ADA)) in the nutrient solution. The highest level of Pb in shoots was between 0.05-0.06% (d.w. on average) using EDTA or ADA, well short of the 1% (d.w.) shoot accumulation target for Pb phytoextraction. The highest level of Pb in the roots (and of all measurements) was with unchelated 500 µM Pb(NO₃)₂; on average 2% (d.w.) accumulated in root. Overall, since S. officinale accumulated Pb predominately in the roots, it is most suited for rhizofiltration and phytostabilisation. Whilst chelating agents enhanced Pb accumulation in shoots, root levels were unexpectedly reduced compared to unchelated Pb treatments. The level of Pb translocated did not completely account for this loss. Minor factors relating to EDTA desorption of roots, EDTA specificity, and charge repulsion of the PbEDTA complex may account for some of the loss, but the main cause remains unclear. In vitro S. officinale cultures were developed and somaclonal variation (involving Pb pre-treatment of petioles) was used as a tool to further investigate, and attempt to improve its Pb phytoremediation potential. The shoots and roots of plants produced from petioles pre-treated with Pb(NO₃)₂ appeared more stressed than those without Pb pre-treatment. After re-treatment with Pb (Pb(NO₃)₂ or PbADA), plants developed from most Pb pre-treated petioles appeared to have reduced Pb accumulation and polyphenol levels, and increased superoxide dismutase activity in roots (although no statistically significant trends were found). Overall, plants produced from Pb pre-treated petioles in this study may have less phytoremediation potential.
6

Untersuchungen über die Entwickelung der Inflorescenz und der Blüthen

Muth, Franz. January 1902 (has links)
Habilitationsschrift--Technische Hochschule, Karlsruhe. / Sonderabdruck aus "Flora oder Allgem. bot. Zeitung," Ergänzungsband 1902.
7

Could Lithospermum officinale be bird dispersed? : A greenhouse experiment

Åberg, Adam January 2015 (has links)
Common gromwell (Lithospermum officinale) acts as a host plant for the monophagous moth Ethmia dodecea  whose larvae are completely dependent on the leaves. As conservation authorities now want to reinstate the regionally extinct moth to Mälardalen, a stable population of its host plant is a requirement. To facilitate the work of strengthening the presence of gromwell a partnership was therefore initiated between Västmanland County Board and Uppsala University. In this cooperation, I performed two studies. In the first one I examined how water and temperature affect plant germination and how nutrient levels affect early growth. In the second study I investigated whether the germination is influenced by chemical treatment (soaking in acid) and mechanical damage (seeds scratched with sandpaper) on the seeds. I worked with the hypothesis that gromwell is grazed by cows and is therefore dispersed and germinates in the spring. This should mean high water levels combined with high temperatures would produce higher germination. For the second study, it means that the germination rate should be higher in the seeds treated with the acid than in the scratched and control treatments. In the first study, so few seeds germinated that I could not draw any conclusions, but germinations appear to go faster in the combination with high nutrients high temperature and frequent watering. In the second study, the seeds scraped with sandpaper had the highest germination rate. This indicates that gromwell may be dispersed by birds, and I propose sandpaper rubbing as a method to easily increase the germination rates of L. officinale in greenhouses in order to reinforce small populations in the field.
8

Repelling Aedes aegypti : A sustainable plant based solution in Lao PDR

Schubert, Fredrik January 2014 (has links)
Abstract Background. Vector borne diseases such as dengue fever and malaria are spread through hematophagous insects. Aedes aegypti is a species of mosquito that transmits dengue and chikungunya in Asia. In Lao PDR the estimated direct and indirect cost of dengue fever alone is 5 million USD. Even though research and innovations in the field of vaccines are moving forward there are yet no effective treatments for these diseases. Vector control methods are in place to suppress the Ae. aegypti population but there are still more than 100,000 cases annually. However, insecticide resistance, mosquito behavioral changes, high costs and health issues make todays measures inadequate. An effective measure is to decrease the mosquito-human contact by applying topical repellents. Aims. This study investigates plants used traditionally for repelling hematophagous insects in Laos, with the aim of finding means to empower local communities to create their own repellents. Methods. After interviewing local communities in Laos and reviewing literature, 24 candidate species were compiled. Lemongrass (Cymbopogon citratus) and ginger (Zingiber officinale) were hydro-distilled to extract essential oils. These oils were then analyzed through GS-MS to understand their chemical composition. Finally the essential oils were formulated with soybean oil to pilot a topical repellent that was tested in vivo on Ae. aegypti under controlled conditions. Results. The formulations elicited about 60 minutes of full protection but when combined, a possible additive effect was noted, prolonging the efficacy by nearly 50%. The main constituents of C. citratus are neral (34.77%) and geranial (56.44%) while, in the more complex, Z. officinale the main components are β-Linalool (9.84%), Geranial (14.44%) and Zingiberene (14.43%). Discussion and conclusions. Botanical repellents are a viable, cheap and sustainable solution of repelling hematophagous disease vectors. The mixture of ginger and lemongrass oil can be further improved in formulation by stabilizing it, and thus prolonging the protection. Increasing yield using alternative means of extracting the essential oils would also make these oils more feasible for commercial production.
9

Desidratação osmótica como alternativa tecnológica para a preservação do gengibre

SIQUEIRA, Leonardo Pereira de 31 January 2014 (has links)
Submitted by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-04-08T18:54:57Z No. of bitstreams: 2 TESE Leonardo Pereira de Siqueira.pdf: 1425392 bytes, checksum: b75c6f73d554c5d23d5f95ff3d7193eb (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-04-08T18:54:57Z (GMT). No. of bitstreams: 2 TESE Leonardo Pereira de Siqueira.pdf: 1425392 bytes, checksum: b75c6f73d554c5d23d5f95ff3d7193eb (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014 / O gengibre é uma planta cujo rizoma tem ampla aceitação na indústria de cosméticos, alimentos e bebidas, além de ser bastante empregado na medicina popular. Após a colheita, a qualidade dos rizomas é reduzida acarretando perdas significativas na qualidade e no tempo de permanência do produto nas prateleiras. O objetivo desta pesquisa foi otimizar o processo de desidratação osmótica do Gengibre. Na implementação foram realizados estudos por meio de planejamento fracionário 27-3 e 23, para avaliar a influência das variáveis independentes: temperatura, concentração da solução osmótica, tempo de imersão, NaCl, geometria de corte, cobertura de alginato e agitação sobre a perda de umidade (PU), o ganho de sólidos (GS) e o índice de desidratação osmótica (IED). Após esta etapa, com objetivo de encontrar as melhores condições de desidratação osmótica para o gengibre, foi realizado um planejamento fatorial 23, para a determinação do melhor tempo de imersão, temperatura e concentração da solução osmótica para processamento. Um planejamento fatorial 22 foi realizado para avaliar a influência das variáveis tempo de imersão e concentração do agente osmótico sobre os coeficientes de difusão da água e da sacarose. Os resultados demonstraram que a presença de NaCl, cobertura, o geometria de corte e a agitação não influenciaram significativamente a perda de umidade e o ganho de sólidos (p>0,05). Entretanto, baixos tempos de imersão e temperatura, associados à alta concentração da solução osmótica resultam em significativa redução do ganho de solutos e satisfatória perda de umidade. As melhores condições encontradas para desidratação osmótica do gengibre foram temperatura 34°C, concentração 44°Brix e tempo de imersão 120 minutos. Em relação aos coeficientes de difusão, ambos foram influenciados pelo tempo de imersão, porém, a concentração do agente osmótico influenciou apenas o coeficiente de difusão da sacarose. Com estes parâmetros, a desidratação osmótica demonstrou ser eficaz para a redução da umidade de gengibres, podendo ser uma alternativa para aumentar a vida útil deste produto.
10

Caracterização parcial do extrato enzimático bruto de gengibre e seu efeito na fragmentação de miofibrilas em carne de frango.

CRUZ, P. L. 26 February 2018 (has links)
Made available in DSpace on 2018-08-01T22:35:19Z (GMT). No. of bitstreams: 1 tese_10545_Resumo da Dissertação Final de Mestrado - Pamela Lemos Cruz PDF.pdf: 54746 bytes, checksum: 9b07e45028c075c94922e97626462fcf (MD5) Previous issue date: 2018-02-26 / A aplicação de proteases é de interesse da indústria de alimentos e o gengibre é uma das fontes vegetais da qual se extrai uma protease de cisteína que tem aplicação na melhoria da textura da carne. Neste contexto, o presente estudo teve como objetivo caracterizar o extrato enzimático bruto de gengibre, avaliar sua atividade proteolítica em proteínas miofibrilares extraídas do músculo Pectoralis major de frango de corte. Posteriormente, foram testados três tratamentos para avaliar seu efeito quando aplicado em peito de frango: Controle (peito de frango), peito de frango adicionado de 5% (m/v) de tampão fosfato 100 mM (pH 7,0) e peito de frango adicionado de 5% (m/v) de extrato enzimático bruto de gengibre. Foram determinados textura instrumental, índice de fragmentação miofibrilar (IFM), comprimento de fragmentos miofibrilares (MFL), comprimento de sarcômero e rendimento pós-cocção. O extrato enzimático bruto de gengibre apresentou temperatura ótima de 60 °C e pH ótimo de 5,5. O extrato enzimático bruto de gengibre apresentou atividade residual de 55,4% a 70 °C e mais de 55% em pH variando de 6 a 8. No estudo cinético utilizando a azocaseína como substrato, foram encontrados valores de Vmax de 23,50 U.mL-1 e Km de 3,47 mg. mL-1. Para o extrato miofibrilar como substrato, foram encontrados valores para Vmax de 1,29 U.mL-1 e Km de 21,48 mg. mL-1, indicando uma menor especificidade do extrato enzimático bruto de gengibre por este substrato. Não houve diferença significativa (p&#8805;0,05) entre os tratamentos para comprimento de sarcômero e rendimento pós-cocção. Houve redução no valor de textura instrumental (p<0,05) e aumento no índice de fragmentação miofibrilar (p<0,01) do tratamento com 5% (m/v) de extrato enzimático bruto de gengibre em relação aos demais tratamentos. Por microscopia de contraste de fases, observou-se que as amostras tratadas com 5% (m/v) de extrato enzimático bruto de gengibre apresentaram miofibrilas com maior grau de fragmentação em comparação com os demais tratamentos, apresentando comprimentos de 4,542 &#956;m, 11,324 &#956;m (Controle) e 10,893 &#956;m para peito de frango adicionado de 5% de tampão fosfato 100 mM (pH 7,0). A aplicação de 5% de extrato enzimático bruto de gengibre em peito de frango, portanto, promoveu a fragmentação das miofibrilas e a redução da força de cisalhamento sem alterar excessivamente a textura da carne e resultar em diminuição do rendimento pós-cocção dos cortes.

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