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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

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.
2

Avalia??o do potencial inseticida de extratos salinos de sementes de seis esp?cies de plantas (fam?lia Fabaceae) contra Aedes (Stegomyia) aegypti (Diptera: Culicidae) L. em diferentes est?gios do ciclo biol?gico

Chagas, Juliana Mac?do 18 March 2016 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-10-26T22:15:38Z No. of bitstreams: 1 JulianaMacedoChagas_DISSERT.pdf: 4021383 bytes, checksum: 512e75f3aa3c0577f75ead12935076d5 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-12-26T17:35:52Z (GMT) No. of bitstreams: 1 JulianaMacedoChagas_DISSERT.pdf: 4021383 bytes, checksum: 512e75f3aa3c0577f75ead12935076d5 (MD5) / Made available in DSpace on 2016-12-26T17:35:52Z (GMT). No. of bitstreams: 1 JulianaMacedoChagas_DISSERT.pdf: 4021383 bytes, checksum: 512e75f3aa3c0577f75ead12935076d5 (MD5) Previous issue date: 2016-03-18 / Atualmente, 4 v?rus podem ser veiculados pelo Aedes aegypti, sendo estes o da Febre amarela urbana, Chikungunya, Zika e o Dengue, este ultimo, ? atualmente o causador de uma das principais doen?as reemergente do mundo. Cerca de 3 bilh?es de pessoas encontram-se sob o risco de se infectarem pelos v?rus. O controle dessas enfermidades ? feito atrav?s do combate ao inseto transmissor, o A. aegypti, por meio da utiliza??o em ampla escala de inseticidas qu?micos, os quais s?o altamente t?xicos para o meio ambiente e para outros animais. Outrossim, estudos mostram que o inseto passou a desenvolver resist?ncia a v?rios desses produtos. Estudos com produtos provenientes de plantas v?m mostrando-se como uma alternativa ?s medidas de controle, uma vez que apresentam baixa toxicidade para mam?feros, reduzido impacto ambiental e, em geral, podem ser facilmente obtidos. No presente estudo analisamos os extratos salinos das sementes das plantas Prosopis juliflora (Sw.) DC. Adenanthera pavonina L.; Clitoria fairchildiana R. A. Howard; Delonix regia (Bojer ex Hook) Raf.; Canavalia ensiformis L. (DC.) e Leucaena leucocephala (Lam.) Wit sobre alguns aspectos importantes no ciclo de A. aegypti. Todos os extratos estudados foram capazes de interferir na vibilidade dos insetos, em algum momento do seu desenvolvimento (ovo, larva e/ou adulto). Complementarmente, a adi??o dos extratos de sementes nas ovitrampas atuaram de forma repelente ? postura de ovos por f?meas gr?vidas de A. aegypti, de maneira dose dependente. Os extratos de P. juliflora e C. fairchildiana tamb?m foram atrativos ? postura at? a concentra??o de 10%. Todos os extratos testados apresentaram toxicidade para o clad?cero Cerodaphinia dubia. N?o obstante se tratar de um material biodegrad?vel foi demonstrado que a fervura dos extratos reduziu a toxicidade, podendo funcionar como m?todo de descarte. Nenhum dos extratos testados apresentou atividade pupicida, indicando que os mecanismos de a??o inseticida s?o dependentes da ingest?o de compostos bioativos. Prote?nas com potencial bioativos, tais como lectinas, prote?nas ligantes a quitina e inibidores de enzimas digestivas foram identificadas em todos os extratos, no entanto, a fervura dos mesmos apenas eliminou a atividade larvicida do extrato de P. juliflora, indicando que as prote?nas, n?o s?o fundamentais para a atividade inseticida dos demais extratos. Mais estudos dever?o ser realizados para confirmar a efic?cia dos extratos em ensaios de semi-campo e campo, bem como a participa??o das prote?nas bioativas e componentes do metabolismo secund?rio para que ent?o possam ser indicados no controle do inseto A. aegypti.
3

What Crawls Beneath

Gneiting, Brent L. 19 March 2013 (has links) (PDF)
Nature is full of mysterious creatures which fascinate and spark imagination. In my final project, What Crawls Beneath, I take a closer look at what drives my interest in creatures that simultaneously attract and repel. Drawing on inspiration from parasites and dinosaurs, I was able to create a piece that represents the danger and beauty that nature so masterfully brings together. The importance of process is discussed as I consider the traditional methods of working with clay and how they affect the outcome of the artwork.
4

Atividades biol?gicas de extratos salinos de sementes de plantas da caatinga contra Aedes Aegypti e investiga??o da participa??o de prote?nas bioativas

Barbosa, Patricia Batista Barra Medeiros 09 June 2014 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-13T13:01:42Z No. of bitstreams: 1 PatriciaBatistaBarraMedeirosBarbosa_TESE.pdf: 3182319 bytes, checksum: 19636ea3271cce1b1b4e72c5e6dfa49c (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2016-01-25T12:17:39Z (GMT) No. of bitstreams: 1 PatriciaBatistaBarraMedeirosBarbosa_TESE.pdf: 3182319 bytes, checksum: 19636ea3271cce1b1b4e72c5e6dfa49c (MD5) / Made available in DSpace on 2016-01-25T12:17:39Z (GMT). No. of bitstreams: 1 PatriciaBatistaBarraMedeirosBarbosa_TESE.pdf: 3182319 bytes, checksum: 19636ea3271cce1b1b4e72c5e6dfa49c (MD5) Previous issue date: 2014-06-09 / A dengue ? a mais importante arbovirose da atualidade, sendo transmitida pela picada do mosquito Aedes aegypti. A aus?ncia de uma vacina profil?tica torna o controle da dengue pautado principalmente no controle do inseto vetor. Todavia os crescentes relatos de resist?ncia e os danos ambientais causados pelos inseticidas qu?micos t?m tornado urgente ? busca por alternativas seguras. Foram preparados 21 extratos brutos (EB) de sementes de plantas da Caatinga. Como extrator foi utilizado o fosfato de s?dio 50mM pH 8.0. Os extratos foram utilizados em bioensaios Aedes aegypti, ensaios de toxicidade e submetidos a uma caracteriza??o parcial para identificar a presen?a de mol?culas bioativas. As an?lises inseticidas foram realizadas por probit e as diferen?as entre os grupos foram constatada por Student?s t-test e ANOVA. Todos os extratos apresentaram atividade larvicida para L1 e L4 e, com exce??o do extrato de G. americana, levaram ao ?bito 100% das larvas (48h). Os EB de M. urundeuva, P. viridiflora, E. velutina, A. cearenses e E. contortisiliquum apresentaram os melhores resultados larvicidas. Do mesmo modo, todos os EB foram repelentes para a postura das f?meas gr?vidas. Os EB de D. grandiflora, E. contortisiliquum, A. cearenses, C. ferrea e C. retusa foram capazes de atrair as f?meas para a posturas quando em baixas concentra??es. Na concentra??o atrativa o EB de E. contortisiliquum foi capaz de levar a ?bito 52% das larvas L1 em 48 h, enquanto que o EB de A. cearenses resultou na morte de 100% dessas larvas em 24h. Os extratos de A. cearenses, P. viridiflora, E. velutina, M. urundeuva e S. brasiliensis tiveram atividade pupicida, enquanto que os extratos de P. viridiflora, E. velutina, E. contortisiliquum, A. cearenses, A. colubrina, D. grandiflora, B. cheilantha, S. spectabilis, C. pyramidalis, M. regnelli e G. americana tiveram a??o adulticidas. Todos os extratos apresentaram toxicidade para C. dubia e os EB de E. velutina e E. contortisiliquum n?o interferiram na viabilidade dos fibroblastos. Considerando todos os ensaios biol?gicos os extratos de A. cearenses, P. viridiflora, E. contortisiliquum, S. brasiliensis, E. velutina e M. urundeuva foram considerados os mais promissores. Em todos os extratos foram identificadas pelo menos duas prote?nas com potencial. O EB de E. contortisiliquum foi selecionado para ser fracionando, j? que n?o apresentou atividade pupicida, indicando que seu mecanismo de a??o larvicida e adulticida resultou da ingest?o de compostos ativos pelos insetos. Al?m disso, esse extrato apresentou o maior teor de prote?na (22 mg/mL) e a maior atividade inibit?ria para as tripsinas das larvas de A. aegypti. Como observado para o EB, as fra??es proteicas de E. contortisiliquum, tamb?m apresentaram atividade larvicida, mas n?o foram pupicida, com destaque para F2 que apresentou maio atividade larvicida e menor toxicidade ambiental do que o EB de origem. A redu??o na atividade proteol?tica das larvas alimentadas com o EB e as fra??es de E. contortisiliquum sugeriu que inibidores de tripsina seriam os respons?vel pela atividade larvicida. Embora o aumento na purifica??o de um inibidor de tripsina de E. contortisiliquum (ITEc) tenha resultado na perda da atividade larvicida, foi constatado que sua aus?ncia reduziu a efic?cia das fra??es, indicando que o ITEc contribui, mas n?o ? suficiente para a atividade larvicida do EB de E. contortisiliquum. Tamb?m n?o foi verificada atividade larvicida e adulticida na fra??o rica em vicilina, e nem evid?ncias da contribui??o dessa mol?cula para a atividade inseticida desse extrato. Os resultados mostram o potencial dos extratos salinos de sementes de planta da Caatinga e, em especial do EB e da F2 de E. contortisiliquum, no controle da popula??o de A. aegypti e indicam que a efic?cia desses extratos deve resultar da a??o conjunta de diferentes compostos ativos, inclusive de natureza proteica, que atuando em diferentes mecanismos s?o capazes de comprometer a viabilidade dos insetos e retardar o surgimento de resist?ncias. / Dengue fever, currently the most important arbovirus, is transmitted by the bite of the Aedes aegypti mosquito. Given the absence of a prophylactic vaccine, the disease can only be controlled by combating the vector insect. However, increasing reports of resistance and environmental damage caused by insecticides have led to the urgent search for new safer alternatives. Twenty - um plant s eed extracts from the Caatinga were prepared , tested and characterized . Sodium phosphate ( 50 mM pH 8.0) was used as extractor. All extracts showed larvicidal and ovipositional deterrence activity . Extracts of D. grandiflora, E. contortisiliquum, A. cearenses , C. ferrea and C. retusa were able to attract females for posture when in low co ncentration . In the attractive concentrations, the CE of E. contortisiliquum and A. cearenses were able to kill 52% and 100% of the larvae respectively . The extracts of A. cearenses , P. viridiflora, E. velutina, M. urundeuva and S. brasiliensis were also pupicides, while extracts of P. viridiflora, E. velutina, E. contortisiliquum , A. cearenses, A. colubrina, D. grandiflora , B. cheilantha , S. spectabilis, C. pyramidalis, M. regnelli e G. americana displayed adulticidal activity. All extracts were toxic to C. dubia zooplankton . The EB of E. velutina and E. contortisiliquum did not affect the viability of fibroblasts . In all extracts were identified at least two potential insecticidal proteins such as enzyme inhibitors, lectins and chitin - binding proteins and components of secondary metabolism . Considering all bioassays , the extracts from A. cearenses, P. viridiflora, E. contortisiliquum , S. brasiliensis, E. velutina and M. urundeuva were considered the most promising . The E. contortisiliquum extracts was the only one who did not show pupicida activity, indicating that its mechanism of action larvicide and adulticidal is related only to the ingesti on of toxic compounds by insect , so it was selected to be fragmenting. As observed for the CE , th e protein fractions of E. contortisiliquum also showed larvicidal activity, highlighting that F2 showed higher larvicidal activity and lower en vironmental toxicity than the CE source. The reduction in the proteolytic activity of larvae fed with crude extra ct and fractions of E. contortisiliquum suggest ed that the trypsin inhibitors ( ITEc) would be resp onsible for larvicidal activity . However the increase in the purification of this inhibitor resulted in loss of larvicidal activity , but the absence of trypsin inhibitor reduced the effectiveness of the fractions , indicating that the ITEC contributes to the larvicidal activity of this extract. Not been observed larvicidal activity and adulticide in rich fraction vicilin, nor evidence of the contribution o f this molecule for the larvicidal activity of the extract. The results show the potential of seeds from plant extracts of Caatinga as a source of active molecules against insects A. aegypti at different stages of its development cycle, since they are comp osed of different active compounds, including protein nature, which act on different mechanisms should result in the death of insec
5

Modifica??o superficial do tecido 100% algod?o tratado com plasma

Freitas, Duciane Oliveira de 24 August 2009 (has links)
Made available in DSpace on 2014-12-17T14:57:52Z (GMT). No. of bitstreams: 1 DucianeOF.pdf: 2916882 bytes, checksum: 4dd79fd7f32c69ce44eb80c291049409 (MD5) Previous issue date: 2009-08-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The 100% cotton fabric (CO)* treated with plasma of methane CH4 has direct application in all areas that needs of aqueous solutions repellent material like coatings and uniforms applied biomedical, aeronautics, and automobile between others. 100% cotton fabric (CO) samples were treated by plasma with two differents atmosphere: Methane gas (CH4), treatment time was varied in 10 in 10 min. until 60 min., and mixture methane/argon (CH4/Ar), it was varied the proportion 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 e 9:1, with treatment time of 30 minutes. In both, the fluxe was 5 sccm (second cubic centimeter), pressure 6 mbar, voltage 490 V and current 0,15A. The objective of work was measure the superficial tension of 100% CO then it treated with plasma, using contact angle measures of water and glycerol with the surface. The samples were tested after treatment, with 8 and 12 months to verify the superficial modification effects. It was verified an increase of hydrophobility with the Sessile drop values varied between 116,69? to 137,85? and it carried on after 12 months. The no treated samples shows contact angle equal 0?. OES analysis and Raman spectroscopy were accomplished. In the SEM analysis was verified oligomers. The plasma treatment is correct environmental, It turning greater than conventional treatments / O tecido 100% Algod?o (CO)* tratado com plasma de metano (CH4) tem aplica??o direta em todas as ?reas que necessitam de um material com maior repel?ncia a solu??es aquosas, como revestimentos e uniformes aplicados a ?rea biom?dica, aeron?utica, automobil?stica, entre outras. Amostras de tecido 100% CO foram tratadas com plasma utilizando duas atmosferas diferentes: g?s CH4, com tempos que variaram de 10 em 10 min. at? 60 min., e uma mistura de metano/arg?nio (CH4/Ar), em propor??es 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 e 9:1, durante 30 min. O fluxo utilizado nos dois processos foi de 5 cm3/s (cent?metro c?bicos por segundo), a uma press?o de 6 mbar , voltagem de 490 V e corrente de 0,15 A. O objetivo do trabalho foi medir a varia??o da tens?o superficial do tecido 100% CO ap?s tratado com plasma; Utilizando medidas de ?ngulo de contato da ?gua e do glicerol com a superf?cie. As amostras foram testadas imediatamente ap?s o tratamento, com 8 e 12 meses, a fim de verificar a dura??o do efeito desta modifica??o superficial. Verificou-se um aumento da hidrofobicidade atrav?s dos valores do teste da gota s?ssil que variaram entre 116,69? a 137,85? e se mantiveram ap?s 12 meses; As amostras n?o tratadas apresentam ?ngulo de contato igual a 0?. An?lises de espectroscopia de emiss?o ?tica (EEO) e espectroscopia Raman (ER) foram realizadas, bem como, an?lise de microscopia eletr?nica de varredura (MEV) a qual confirmou presen?a de olig?meros. O processo a plasma ? ambientalmente correto e se torna superior em compara??o aos tratamentos convencionais

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