• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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

Avalia??o da efic?cia de aditivo anti-micotoxina em leitoas pr?-p?beres intoxicadas experimentalmente com zearalenona / Effectiveness evaluation of anti-mycotoxin additive in pre-pubertal gilts experimentally intoxicated with zearalenone

VASCONCELOS, Bruno da Silva de 08 March 2013 (has links)
Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-03-27T18:09:28Z No. of bitstreams: 1 2013 - Bruno da Silva de Vasconcelos.pdf: 1120255 bytes, checksum: fb4b9f0cfbb71f486cabed4da08b9948 (MD5) / Made available in DSpace on 2018-03-27T18:09:29Z (GMT). No. of bitstreams: 1 2013 - Bruno da Silva de Vasconcelos.pdf: 1120255 bytes, checksum: fb4b9f0cfbb71f486cabed4da08b9948 (MD5) Previous issue date: 2013-03-08 / Brazil has a prominent pork production and it is among the leading of producers and exporters of meat pork in the world. Today, the type of Brazilian pig produced, is of high quality and requires special care, starting at the quality of food, to provided maximum expression of genetic potential. The staple diet of the pig is soy and corn, these can be affected by fungi, which when in favorable conditions to their growth, colonize grain and use their nutrients to their development. As a result, can occur the production of mycotoxins and secondary metabolites, which can be toxic to animals. Zearalenone (ZEA) is a mycotoxin with estrogenics properties which leads to huge losses, especially in reproduction, where it causes abortion, pseudopregnancy, stillbirths, among other symptoms. The use of anti-mycotoxin additive added to the feed is an example of how to prevent it. The yeast wall is a new alternative of adsorbent to be tested. This study aimed to evaluate the effect of an anti-mycotoxin additive, of yeast wall, and the effects of mycotoxin ZEA in prepubertal gilts. A total of 36 prepubertal gilts were divided in 4 treatments: T1 ( ration), T2 (ration + adsorbent), T3( ration + toxin),T4 (ration +toxin+ adsorbent). The concentration used of ZEA were 2 ppm, maximum concentration of the limit established to register as a antimycotoxin additive according to Brazilian laws and the concentration used of anti-mycotoxin additive were 0,2%, gained on earlier in vitro studies. The animals were fed for 21 days with the toxin, weighted and measured the vulva, at the end of treatment were slaughtered for evaluation of the reproductive tract. The results showed no significant statistic difference in feed conversion and live weight between treatments. There were performance reduce in weight gain and feed intake on T3. About measured of vulva, the mean of weight and length of the reproductive tract were significant differences in the treatments with ZEA 2ppm. The adsorbent used was not effective in preventing ZEA mycotoxicosis by the 2ppm, probably due to saturation of the anti-mycotoxin additive molecule by metabolites of the ZEA, that was in higher quantity than mannanoligosaccharide, overtaking the adsorbtive capacity of adsorbent. / O Brasil possui uma produ??o de su?nos de destaque, estando entre os principais produtores e exportadores de carne su?na no mundo. Hoje, o tipo de su?no brasileiro produzido ? de extrema qualidade e requer cuidados especiais, iniciando na qualidade de alimento fornecido, para express?o m?xima do potencial gen?tico. A base da alimenta??o do su?no ? a soja e o milho, e estes gr?os podem ser contaminados por fungos que por sua vez em condi??es favor?veis ao seu crescimento, colonizam os gr?os e utilizam os seus nutrientes para o seu desenvolvimento. Como consequ?ncia pode ocorrer ? produ??o de micotoxinas, metab?litos secund?rios, que podem ser t?xicos aos animais. A zearalenona (ZEA) ? uma micotoxina com propriedades estrog?nicas e que leva a enormes preju?zos, principalmente na reprodu??o, pois pode causar aborto, pseudogesta??o, natimortos, entre outros sintomas. O uso de aditivo anti-micotoxina adicionados na ra??o ? um exemplo de como se prevenir e define-se como uma subst?ncia que por processos f?sico-qu?micos, enzim?ticos e/ou bacterianos se unem a micotoxina, impedindo que esta seja absorvida pelo organismo animal e seja posteriormente eliminada. A parede celular de leveduras ? uma nova alternativa, de adsorvente, a ser testada. O presente trabalho teve como objetivo avaliar o efeito de um aditivo antimicotoxina, a base de parede celular de leveduras, e os efeitos da micotoxina ZEA em leitoas pr?-p?beres. Foram utilizadas 36 leitoas pr?-p?beres divididas em 4 tratamentos: T1(s? ra??o), T2 (ra??o + adsorvente), T3 (ra??o + toxina), T4 (ra??o + toxina + adsorvente). A concentra??o de ZEA utilizada foi de 2ppm, concentra??o m?xima do limite estabelecido para registro de aditivo antimicotoxina segundo as leis brasileiras, e a concentra??o usada de aditivo anti-micotoxina foi de 0,2%, obtidos anteriormente em estudos in vitro. Os animais foram alimentados por 21 dias com a toxina, pesados e feita vulvometria. No final do per?odo experimental foram abatidos para avalia??o do trato reprodutivo. Os resultados encontrados mostraram que n?o houve diferen?a estat?stica significativa no peso vivo e na convers?o alimentar entre os tratamentos. No consumo e no ganho de peso do T3 houve queda no desempenho. Na vulvometria, as m?dias do peso e do comprimento do trato reprodutivo tiveram diferen?a significativa nos tratamentos que levaram ZEA a 2ppm. O aditivo anti-micotoxina utilizado n?o foi eficaz na preven??o da micotoxicose por ZEA a 2ppm, j? que as leitoas manifestaram os sinais caracter?sticos da doen?a provavelmente devido a satura??o da mol?cula adsorvente pelos metab?litos de ZEA, que encontravam-se em maior quantidade que os mananoligaossacar?deos, ao ponto de ultrapassar a capacidade adsortiva do aditivo.
2

Triboqu?mica: intera??o de insertos met?licos roscados metal-osso maxilar / Tribochemical: threaded metal inserts interaction metal-bone

Pontes, Gracilene dos Santos Aquino 26 February 2016 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-02T12:02:52Z No. of bitstreams: 1 GracileneDosSantosAquinoPontes_DISSERT.pdf: 15314465 bytes, checksum: 08443c4598fd6bb9ee7c3a2fcde8a8d9 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-07T15:40:36Z (GMT) No. of bitstreams: 1 GracileneDosSantosAquinoPontes_DISSERT.pdf: 15314465 bytes, checksum: 08443c4598fd6bb9ee7c3a2fcde8a8d9 (MD5) / Made available in DSpace on 2017-02-07T15:40:37Z (GMT). No. of bitstreams: 1 GracileneDosSantosAquinoPontes_DISSERT.pdf: 15314465 bytes, checksum: 08443c4598fd6bb9ee7c3a2fcde8a8d9 (MD5) Previous issue date: 2016-02-26 / Implantes dent?rios s?o suportes ou estruturas de materiais biocompat?veis posicionados cirurgicamente no osso maxilar, abaixo da gengiva, para substituir ra?zes dent?rias, assegurando estruturalmente dentes artificiais ap?s a perda da denti??o. Desenvolveu-se um m?todo de ensaio, em laborat?rio, para analisar a resposta mec?nica de um parafuso met?lico implantado em um osso maxilar inanimado de um porco de cerca de doze meses de idade e imerso em um fluido com tr?s condi??es de pH: ?cido, b?sico e neutro. Uma solicita??o mec?nica de contato circunferencial c?clico para simular um processo mastigat?rio unidirecional foi utilizada para investigar a estabilidade dimensional da uni?o parafuso-osso em fun??o do n?mero de ciclos sob carga. Ap?s os ensaios com a presen?a de solu??o ?cida, b?sica ou neutra, analisou-se a estrutura porosa do osso maxilar su?no bem como da cabe?a do parafuso submetida ao contato metal-metal atrav?s de MEV e microan?lise por EDS. Os resultados das solicita??es triboqu?micas da uni?o parafuso-osso evidenciaram, na cabe?a do parafuso, a ocorr?ncia de desgaste abrasivo com forma??o de proa com presen?a de debris e, no osso, dano por fratura fr?gil com a presen?a de microtrincas em meio ? sua porosidade intr?nseca. As taxas de desgaste por perda m?ssica do parafuso desatarraxado ap?s cada ensaio demonstraram surpreendentemente serem menores quando resultantes dos ensaios com solu??o ?cida e b?sica, enquanto foram maiores as taxas de desgaste dos parafusos ensaiados em meio a uma solu??o neutra. O contato aqueceu em uma faixa que variou entre 0,50C at? 16,50C acima da temperatura ambiente. Assim, atribuiu-se ? a??o ?cida do fluido aquecido pelo atrito entre os contatos sobre o parafuso met?lico a forma??o de uma nanocamada passivada, respons?vel pelo menor desgaste medido. A velocidade de vibra??o global foi maior durante o running in, at? 104 ciclos, do que no regime permanente de ensaios, entre 104 e 105 ciclos, quando o contato j? se configurara como conforme. O NPS[dB], n?vel de press?o sonora seguiu esta tend?ncia. O pH do fluido continuou ?cido antes e ap?s os ensaios, embora haja migrado de 2, no in?cio, para 4, no final. Os demais permaneceram invari?veis. / Dental implants are material supports and structures biocompatible surgically positioned into the maxillary bone beneath the gums to replace tooth roots, ensuring structurally teeth substitutes after the loss of teeth. We have developed an approach in the laboratory to analyze the mechanical response of a metallic screw implanted in an inanimate jaw bone of a pig about twelve months of age and immersed in a fluid at three pH conditions: acidic, basic and neutral. A mechanical stress cyclic circumferential contact to simulate a unidirectional masticatory process was used to investigate the dimensional stability of the screw-bone junction in the number of cycles under load. After the tests on the presence of acidic, basic or neutral solution, it analyzed the porous structure of the pig maxillary bone and screw head subjected to metal-to-metal contact through MEV and EDS microanalysis. The results of tribochemical requests the screw-bone junction showed in the screw head, the occurrence of abrasive wear with bow training with the presence of debris and bone, damage by brittle fracture in the presence of microcracks in the midst of their inherent porosity. The wear rates of mass loss of undoing screw after each test showed surprisingly are lower when resulting from tests with acidic and basic solution, as were higher wear rates of the tested screws in the middle of a neutral solution. The contact heated in a band ranging from 0,5oC to 16,5oC above room temperature. Therefore, attributed to the acid action of the fluid heated by the friction between the contacts on the metal bolt the formation of a passivated nanolayer responsible for the lowest measured wear. The overall vibration velocity was higher during the running in, up to 104 cycles, than in steady-state tests, between 104 and 105 cycles, when the contact already configures as conformal. SPL [dB] Sound Pressure Level followed this trend. The pH of the acid fluid continued before and after the test, although there is migrated from 2 at the beginning, 4 at the end. The rest remained unchanged.

Page generated in 0.0288 seconds