• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 30
  • 25
  • 4
  • 2
  • 2
  • 1
  • Tagged with
  • 66
  • 33
  • 16
  • 12
  • 11
  • 10
  • 9
  • 9
  • 9
  • 8
  • 7
  • 7
  • 7
  • 6
  • 6
  • 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.
51

Magma-Crust Interaction at Subduction Zone Volcanoes

Jolis, Ester M. January 2013 (has links)
The focus of this work is magma-crust interaction processes and associated crustal volatile release in subduction zone volcanoes, drawing on rock, mineral, and gas geochemistry as well as experimental petrology. Understanding the multitude of differentiation processes that modify an original magma during ascent to the surface is vital to unravel the contributions of the various sources that contribute to the final magmas erupted at volcanoes. In particular, magma-crust interaction (MCI) processes have been investigated at a variety of scales, from a local scale in the Vesuvius, Merapi, and Kelut studies, to a regional scale, in the Java to Bali segment of the Sunda Arc.  The role of crustal influences is still not well constrained in subduction systems, particulary in terms of the compositional impact of direct magma crust interplay. To address this shortcoming, we studied marble and calc-silicate (skarn) xenoliths, and used high resolution short timescale experimental petrology at Vesuvius volcano. The marbles and calc-silicates help to identify different mechanisms of magma-carbonate and magma-xenolith interaction, and the subsequent effects of volatile release on potential eruptive behaviour, while sequential short-duration experiments simulate the actual processes of carbonate assimilation employing natural materials and controlled magmatic conditions. The experiments highlight the efficiency of carbonate assimilation and associated carbonate-derived CO2 liberated over short timescales. The findings at Merapi and Kelut demonstrate a complex magmatic plumbing system underneath these volcanoes with magma residing at different depths, spanning from the mantle-crust boundary to the upper crust. The erupted products and volcanic gas emissions enable us to shed light on MCI-processes and associated volatile release in these systems. The knowledge gained from studying individual volcanoes (e.g., Merapi and Kelut) is then tested on a regional scale and applied to the entire Java and Bali arc segment. An attempt is presented to distinguish the extent of source versus crustal influences and establish a quantitative model of late stage crustal influence in this arc segment. This thesis therefore hopes to contribute to our knowledge of magma genesis and magma-crust interaction (MCI) processes that likely operate in subduction zone systems worldwide.
52

Low cement structural lightweight concrete with optimized multiple waste mix design / Concreto leve estrutural de baixo consumo de cimento com misturas otimizadas de res?duos

Sampaio, Zodinio Laurisa Monteiro 25 April 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-11-22T20:18:43Z No. of bitstreams: 1 ZodinioLaurisaMonteiroSampaio_TESE.pdf: 4245538 bytes, checksum: 687e089323cb706bdb8dc70fe1aa7593 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-11-23T00:28:27Z (GMT) No. of bitstreams: 1 ZodinioLaurisaMonteiroSampaio_TESE.pdf: 4245538 bytes, checksum: 687e089323cb706bdb8dc70fe1aa7593 (MD5) / Made available in DSpace on 2017-11-23T00:28:27Z (GMT). No. of bitstreams: 1 ZodinioLaurisaMonteiroSampaio_TESE.pdf: 4245538 bytes, checksum: 687e089323cb706bdb8dc70fe1aa7593 (MD5) Previous issue date: 2017-04-25 / The high-energy demand involved in the construction industry and the increasing consumption of concrete made this material an ideal option for the recycling of by-products from various industries such as: porcelain polishing residue (PPR); tire rubber residue (TRR) and limestone residue (LSR). These residues often lack a treatment that contributes to the degradation of the environment. In this sense, the use of by-products that increases the volume of the concrete without damaging significantly its properties, can be a viable option in the production of low-cost and sustainable low-weight concrete (LWC). The main objective of this work was to analyze the mechanical and thermal behavior of structural lightweight concrete (SLWC) with low cement consumption, produced with expanded clay (EC) in replacement of the aggregate and with the addition of PPR, TRR and LSR to replace the small aggregate. For this purpose, a 2? factorial design was used for the choice of SLWC with the best performance in terms of consistency, mechanical properties and density. Subsequently, reductions of 10, 20 and 30% of cement were performed on SLWC that presented better combination of properties and waste consumption and were characterized by mechanical tests. The best SLWC mix resulting from the combination of mechanical properties and cement consumption was characterized by permeability, flexural strength, TG/DTA, XRF, SEM, thermal capacity, thermal conductivity and thermal diffusivity. The results showed that residues contents around 21% presented better combination of properties. By maintaining the amount of residue at optimum levels it was possible to produce a SLWC with good rheological, mechanical and thermal properties with minimum cement consumption. / A alta demanda energ?tica envolvida na ind?stria da constru??o civil e o crescente consumo do concreto, fez com que o concreto se tornasse a op??o ideal para a reciclagem de subprodutos de v?rias industrias tais como: res?duo de polimento de porcelanato PPR; res?duo de borracha de pneu (TRR) e res?duo de pedra calc?ria (LSR). Esses res?duos frequentemente carecem de um tratamento adequando o que acaba contribuindo para a degrada??o do meio ambiente. Nesse sentido, o uso de subprodutos que ir?o aumentar o volume do concreto sem prejudicar muito as propriedades, pode ser uma op??o bastante vi?vel na produ??o de Concretos leves (CL) de baixo custo e sustent?veis. O objetivo geral desse trabalho foi analisar o comportamento mec?nico e t?rmico de concretos leves estruturais (CLE) de baixo teor de cimento produzidos com argila expandida (AE) em substitui??o ao agregado gra?do e com adi??o de PPR, TRR e LSR em substitui??o a parte do agregado mi?do. Para tal foi usado inicialmente um planejamento fatorial 2? para a escolha dos CLE com melhor desempenho em termos de consist?ncia, propriedades mec?nicas e massa espec?fica real. Posteriormente foram realizadas redu??es de 10, 20 e 30% de cimento nos CLE que apresentaram melhores desempenhos e caracterizados atrav?s de ensaios mec?nicos. O melhor tra?o resultante da combina??o de propriedades mec?nicas com o consumo de cimento foi caracterizado mediante ensaios de: permeabilidade; resist?ncia ? flex?o; TG/DTA; FRX; MEV; capacidade t?rmica; condutividade t?rmica e difusividade t?rmica. Por fim. Os resultados mostraram que teores de res?duos em torno de 21% apresentaram melhor combina??o de propriedades. Mantendo os teores de res?duos em n?veis ?timos foi poss?vel produzir um CLE com boas propriedades reol?gicas, mec?nicas e t?rmicas com um consumo m?nimo de cimento.
53

Avalia??o do efeito da adi??o de res?duo de borracha de pneu e brita calc?ria na formula??o de comp?sitos ciment?ceos

Silva Junior, Francisco Alves da 30 May 2014 (has links)
Made available in DSpace on 2014-12-17T14:07:22Z (GMT). No. of bitstreams: 1 FranciscoASJ_TESE.pdf: 8792658 bytes, checksum: 82015e9b1bc788b7c608317086cdc276 (MD5) Previous issue date: 2014-05-30 / Researches have shown that the introduction of rubber in concrete improves the features of its deformability, as well as contributes to environmental disposal of waste generated in the tire retreading process. Furthermore, there is a high availability of limestone within RN and CE country. Ignorance about this stone, does not allow its wide use as aggregate, leaving, this abundant supply idle. A composite of limestone gravel, with proportions of tire rubber waste which could be used as concrete would be an alternative to concrete for low applications. Therefore, this research aims to evaluate the characteristics of concrete containing limestone gravel and proportions of little aggregate replacement (sand) by tire rubber waste. To this goal, the material components of the concrete were characterized, concrete specimens with limestone gravel were made, from the dash 1.0: 2.5: 3.5, varying the water/cement ratio, and inserting a commercial plasticizer, without a proportion of residue, known as reference. From this, concrete with and without the presence of the additive in the same proportions were chosen, as well as these with the use of granite gravel, for being the most used. Selected the references, to these, replacements of little aggregate (sand) were added replaced by rubber waste from the tire retreading process, treated with 1M NaOH in proportions from 5.0 to 20.0 % by mass, cured and exposed to the semiarid environment. The results indicate the possibility of using limestone gravel in the concrete composition with workability correction using plasticizer. There was a decrease in the mechanical properties of the concrete with increments of waste rubber, but there is an improvement in toughness and deformability of the composite, which makes it interesting for the construction of non-structural concrete floors, as well as, the rubber waste delayed the hardening process, continuing to gain resistance after 28 days / Pesquisas t?m mostrado que a introdu??o de borracha no concreto melhoram as caracter?sticas de deformabilidade deste, assim como, contribuem para destina??o ambiental de res?duos gerados no processo de recauchutagem de pneus. Somado a isto, existe uma alta disponibilidade de rocha calc?ria no interior do RN e do CE. O n?o conhecimento desta pedra, n?o possibilita sua ampla utiliza??o como agregado, deixando, esta farta oferta ociosa. Um comp?sito de brita do tipo calc?ria, com propor??es de res?duo de borracha de pneu que pudesse ser utilizado como concreto seria uma alternativa para concretos destinados a baixas solicita??es. Logo, este trabalho possui como objetivo a avalia??o das carater?sticas de concretos contendo brita calc?ria e propor??es de substitui??o do agregado mi?do (areia) por res?duo de borracha de pneus. Para tanto, caracterizou-se os materiais componentes do concreto, confeccionou-se corpos de prova de concretos com brita calc?ria, a partir do tra?o 1,0: 2,5: 3,5, variando-se a rela??o ?gua/cimento, e inserindo-se um plastificante comercial, sem a propor??o de res?duo, chamados de refer?ncia. A partir deste, foram escolhidos nas mesmas propor??es concretos com e sem a presen?a do aditivo, assim como, estes com a utiliza??o da brita gran?tica, por ser a mais utilizada. Escolhidas as refer?ncias, a estas foram acrescidas substitui??es de parte do agregado mi?do (areia) por res?duo de borracha de pneu proveniente do processo de recauchutagem, tratados com NaOH 1 M, nas propor??es de 5,0 a 20,0 % em massa, curados e expostos ao ambiente semi?rido. Os resultados indicam a possibilidade de utiliza??o da brita calc?ria na composi??o do concreto com corre??o da trabalhabilidade utilizando-se plastificante. Observou-se uma diminui??o nas propriedades mec?nicas dos concretos com incrementos de res?duo de borracha, por?m existe uma melhora de tenacidade, e deformabilidade do comp?sito, o que o torna interessante para a constru??o de pisos de concretos n?o estruturais, assim como, o res?duo retardou o processo de endurecimento, continuando o concreto a ganhar resist?ncia, ap?s os 28 dias
54

Efeitos da stanniocalcina 1 sobre a diferenciação osteogênica das células tronco adiposo-derivadas humanas

Terra, Silvia Resende January 2016 (has links)
A stanniocalcina-1 (STC1) é uma glicoproteína caracterizada como um fator endócrino com ação anti-hipercalcêmica/hipocalcêmica originalmente descoberta em peixes. Em mamíferos, esse hormônio está expresso em praticamente todos os tecidos, regula diversas funções biológicas e atua como um fator autócrino/ parácrino. Diversas evidências demonstram o envolvimento da STC1 no desenvolvimento ósseo. Durante a embriogênese, a STC1 é expressa nos primeiros estágios de condensação mesenquimal e, posteriormente, se mantém restrita a preosteoblastos e osteoblastos maduros. Além disso, a STC1 estimula a mineralização óssea através do aumento da expressão de transportadores de fosfato e da osteopontina, uma sialoglicoproteína que atua na mineralização óssea. Células-tronco adultas simbolizam atualmente a fonte mais acessível de células progenitoras utilizadas em terapias celulares e engenharia de tecidos. O tecido adiposo contém uma população de células biológica e clinicamente interessantes denominada células tronco adiposo derivadas (CTADs). Atualmente as CTADs são a melhor fonte de células tronco adultas podendo ser obtidas através de procedimentos minimamente invasivos. Um grande número de estudos têm demonstrado o potencial osteogênico dessas células, no entanto, ainda é um desafio a compreensão dos mecanismos envolvidos na diferenciação osteogênica a partir das CTADs. Neste estudo, foi demonstrado que sete dias de indução osteogênica das CTADs na presença de 50 ng/mL de STC1 aumentaram significativamente a expressão gênica e proteica dos marcadores osteogênicos: fosfatase alcalina (FA), runt related gene 2 (RUNX2) e osteopontina (OPN) O aumento na atividade da enzima FAS foi relacionado diretamente com a maior expressão gênica e proteica. Além disso, a STC1 modula a via de sinalização pAKt/pGSK3-β/βcatenina em preosteoblastos de 7 dias sugerindo que seus efeitos sobre a osteogênese sejam mediados por essa via de sinalização. O peptídeo neuroendócrino CGRP (peptídeo relacionado ao gene da calcitonina) possui similaridades com STC1 e desempenha um importante papel nas fases iniciais da diferenciação dos osteoblastos. O CGRP ativa o receptor CALCRL, formando um dímero com a proteína transmembrana acessória RAMP1. Para elucidar o envolvimento da STC1 nas vias de sinalização relacionadas a receptores de calcitonina foi investigado o efeito desse hormônio na modulação 8 do receptor do CGRP e receptor de calcitonina (CTR) em CTADs diferenciadas para preosteoblastos e células Hek 293 superexpressoras de CALCRL/RAMP1 e CTR. A STC1 não alterou a expressão dos genes CALCRL e ramp1 durante a osteoblastogênese mas provocou alterações na distribuição espacial do complexo CALCRL/RAMP1 na membrana plasmática de preosteoblastos, induzindo a formação de clusters Além do efeito sobre a sinalização do CGRP a STC1 demonstrou inibir a sinalização da calcitonina diminuindo a produção de cAMP em células transfectadas com CTR. A STC1 não alterou os níveis intracelulares de cálcio e ATP. Esses resultados indicam que, embora não atue diretamente via os receptores CALCRL/RAMP1 e CTR, a STC1 modula a sinalização dos peptídeos CGRP e CT. Estudos mais detalhados sobre os efeitos da STC1 nas diferentes vias de sinalização são necessários para desvendar completamente os mecanismos de diferenciação osteogênicos das CTADs estimuladas por esse hormônio. / The stanniocalcin-1 (STC1) is a glycoprotein characterized as an endocrine factor with anti-hypercalcemic / hypocalcemic action, originally identified in fish. The hormone in mammals is expressed in virtually all tissues and regulates diverse biological functions, acting as an autocrine / paracrine factor. Many evidences demonstrate that STC1 is able to regulate bone development. During embryogenesis the STC1 is expressed in early stages of mesenchymal condensation and thereafter remains restricted to preosteoblast and mature osteoblast. Furthermore, STC1 stimulates bone mineralization by increasing the phosphate transporter expression and osteopontin, a sialoglycoprotein involved in bone mineralization. Adult stem cells currently symbolize the most accessible source of stem cells used in cell therapy and tissue engineering. Adipose tissue contains a population of biological cells clinically interesting called adipose derived stem cells (ASC). Currently, the ASCs are the best source of adult stem cells and can be harvested using minimally invasive procedures. A large number of studies had shown osteogenic potential of these cells, however, it is still a challenge to understand the mechanisms involved in osteogenic differentiation from ASCs This study demonstrated that 7-day preosteoblast in the presence of 50 ng / ml STC1 significantly increased gene and protein expression of osteogenic markers: alkaline phosphatase (ALP), runt related gene 2 (RUNX2), and osteopontin (OPN ). Also, there was an increase in the enzymatic activity of the ALP, possibly related to both gene and protein expression. Furthermore, STC1 modulates pAkt / pGSK3-β / βcatenina signaling in 7-day preosteoblast, suggesting that the STC1 effects on the osteogenesis is mediated by this pathway. The neuroendocrine peptide CGRP (calcitonin gene related peptide) has similarities to STC1 and plays an important role in the early stages of osteoblast differentiation. The active CGRP receptor form a dimer with the receptor activity-modifying protein 1 (RAMP1). To elucidate the involvement of STC1 in signaling pathways related to calcitonin receptors, it was investigated the STC1 effect on peptide receptor modulating the calcitonin gene related peptide (CGRP) and the calcitonin receptor (CTR) in 7-day preosteoblast, and in Hek 293 cells transfected with CALCRL / RAMP1 and CTR The STC1 did not change the expression of genes CALCRL and ramp1 during osteoblastogenesis but modified the plasma membrane spatial distribution of 10 CALCRL/RAMP1 in preosteoblast. Besides the effect on CGRP signaling, STC1 inhibited the calcitonin signaling by decreasing cAMP production in cells transfected with CTR. The STC1 did not alter intracellular calcium levels and ATP. These results indicated that STC1 does not act on the same receptors for calcitonin and CGRP, but modulates the action of these peptides. Studies on the effects of STC1 in different signaling pathways are necessary for understanding the mechanisms underlying the STC1 ability in enhancing osteoblastogenesis from hASCs.
55

Estudo e caracteriza??o de mat?rias-primas para o desenvolvimento de blocos s?lico-calc?rios

Andrade, Jean Carlos Silva 24 March 2009 (has links)
Made available in DSpace on 2014-12-17T14:57:52Z (GMT). No. of bitstreams: 1 JeanCSA.pdf: 2642121 bytes, checksum: ee65334424753f93878bcb16392de432 (MD5) Previous issue date: 2009-03-24 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The types of products manufactured calcium silicate blocks are very diversified in its characteristics. They include accessory bricks, blocks, products in dense material, with or without reinforcements of hardware, great units in cellular material, and thermal insulating products. The elements calcium silicate are of great use in the prefabricated construction, being formed for dense masses and hardened by autoclaving. This work has for objective develop formulations that make possible the obtaining of calcium silicate blocks with characteristics that correspond the specifications technical, in the State of the Rio Grande of the North, in finality of obtaining technical viability for use in the civil construction. The work studied the availability raw materials from convenient for the production of calcium silicate blocks, and the effect of variations of the productive process on the developed products. The studied raw materials were: the quartz sand from the city of S?o Gon?alo do Amarante/RN, and two lime, a hydrated lime and a pure lime from the city of Governador Dix-Sept Rosado/RN. The raw materials collected were submitted a testes to particle size distribution, fluorescence of X rays, diffraction of X rays. Then were produced 8 formulations and made body-of-test by uniaxial pressing at 36 MPa, and cured for 7 hours at about 18 kgf/cm2 pressing and temperature of approximately 180 ?C. The cure technological properties evaluated were: lineal shrinkage, apparent density, apparent porosity, water absorption, modulus of rupture flexural (3 points), resistance compression, phase analysis (XRD) and micromorphological analysis (SEM). From the results presented the technological properties, was possible say that utilization of hydrated lime becomes more viable its utilization in mass limestone silica, for manufacture of calcium silicate blocks / Os tipos de produtos s?lico-calc?rios fabricados s?o muito diversificados em suas caracter?sticas. Eles incluem tijolos, blocos, produtos acess?rios em material denso, com ou sem refor?os de ferragem, grandes unidades em material celular, e produtos isolantes t?rmicos. Os elementos s?lico-calc?rios s?o de grande utiliza??o na constru??o pr?-fabricada, sendo formados por massas densas e endurecidos em autoclave. Este trabalho teve como objetivo desenvolver formula??es que possibilitem a obten??o de blocos s?lico-calc?rios com caracter?sticas que correspondem ?s especifica??es t?cnicas, no Estado do Rio Grande do Norte, na finalidade de obter viabilidade t?cnica para uso na constru??o civil. O trabalho estudou a disponibilidade de mat?rias-primas convenientes para a produ??o de blocos s?lico-calc?rios, e o efeito das varia??es do processo produtivo sobre os produtos desenvolvidos. As mat?rias-primas estudadas foram: uma areia quartzosa oriunda do munic?pio de S?o Gon?alo do Amarante/RN, e duas cal, uma cal hidratada e uma cal virgem oriundas do munic?pio de Governador Dix-Sept Rosado/RN. As mat?rias-primas coletadas foram submetidas a ensaios de distribui??o de tamanho de part?cula, fluoresc?ncia de raios X, difra??o de raios X. Em seguida foram produzidas 8 formula??es e confeccionados corpos-de-prova por prensagem uniaxial a 36 MPa, e curados durante 7 horas em press?o de aproximadamente 18 kgf/cm2, e temperatura de aproximadamente 180?C. As propriedades tecnol?gicas de cura avaliadas foram: retra??o linear, massa espec?fica aparente, porosidade aparente, absor??o de ?gua, m?dulo de ruptura ? flex?o em 3 pontos, resist?ncia a compress?o, an?lise fases (DRX) e an?lise micromorfol?gica (MEV). A partir dos resultados apresentados das propriedades tecnol?gicas, foi poss?vel afirmar que a utiliza??o da cal hidratada torna-se mais vi?vel sua utiliza??o em massas s?lico-calc?rias, para fabrica??o de blocos s?lico-calc?rios
56

Efeitos da stanniocalcina 1 sobre a diferenciação osteogênica das células tronco adiposo-derivadas humanas

Terra, Silvia Resende January 2016 (has links)
A stanniocalcina-1 (STC1) é uma glicoproteína caracterizada como um fator endócrino com ação anti-hipercalcêmica/hipocalcêmica originalmente descoberta em peixes. Em mamíferos, esse hormônio está expresso em praticamente todos os tecidos, regula diversas funções biológicas e atua como um fator autócrino/ parácrino. Diversas evidências demonstram o envolvimento da STC1 no desenvolvimento ósseo. Durante a embriogênese, a STC1 é expressa nos primeiros estágios de condensação mesenquimal e, posteriormente, se mantém restrita a preosteoblastos e osteoblastos maduros. Além disso, a STC1 estimula a mineralização óssea através do aumento da expressão de transportadores de fosfato e da osteopontina, uma sialoglicoproteína que atua na mineralização óssea. Células-tronco adultas simbolizam atualmente a fonte mais acessível de células progenitoras utilizadas em terapias celulares e engenharia de tecidos. O tecido adiposo contém uma população de células biológica e clinicamente interessantes denominada células tronco adiposo derivadas (CTADs). Atualmente as CTADs são a melhor fonte de células tronco adultas podendo ser obtidas através de procedimentos minimamente invasivos. Um grande número de estudos têm demonstrado o potencial osteogênico dessas células, no entanto, ainda é um desafio a compreensão dos mecanismos envolvidos na diferenciação osteogênica a partir das CTADs. Neste estudo, foi demonstrado que sete dias de indução osteogênica das CTADs na presença de 50 ng/mL de STC1 aumentaram significativamente a expressão gênica e proteica dos marcadores osteogênicos: fosfatase alcalina (FA), runt related gene 2 (RUNX2) e osteopontina (OPN) O aumento na atividade da enzima FAS foi relacionado diretamente com a maior expressão gênica e proteica. Além disso, a STC1 modula a via de sinalização pAKt/pGSK3-β/βcatenina em preosteoblastos de 7 dias sugerindo que seus efeitos sobre a osteogênese sejam mediados por essa via de sinalização. O peptídeo neuroendócrino CGRP (peptídeo relacionado ao gene da calcitonina) possui similaridades com STC1 e desempenha um importante papel nas fases iniciais da diferenciação dos osteoblastos. O CGRP ativa o receptor CALCRL, formando um dímero com a proteína transmembrana acessória RAMP1. Para elucidar o envolvimento da STC1 nas vias de sinalização relacionadas a receptores de calcitonina foi investigado o efeito desse hormônio na modulação 8 do receptor do CGRP e receptor de calcitonina (CTR) em CTADs diferenciadas para preosteoblastos e células Hek 293 superexpressoras de CALCRL/RAMP1 e CTR. A STC1 não alterou a expressão dos genes CALCRL e ramp1 durante a osteoblastogênese mas provocou alterações na distribuição espacial do complexo CALCRL/RAMP1 na membrana plasmática de preosteoblastos, induzindo a formação de clusters Além do efeito sobre a sinalização do CGRP a STC1 demonstrou inibir a sinalização da calcitonina diminuindo a produção de cAMP em células transfectadas com CTR. A STC1 não alterou os níveis intracelulares de cálcio e ATP. Esses resultados indicam que, embora não atue diretamente via os receptores CALCRL/RAMP1 e CTR, a STC1 modula a sinalização dos peptídeos CGRP e CT. Estudos mais detalhados sobre os efeitos da STC1 nas diferentes vias de sinalização são necessários para desvendar completamente os mecanismos de diferenciação osteogênicos das CTADs estimuladas por esse hormônio. / The stanniocalcin-1 (STC1) is a glycoprotein characterized as an endocrine factor with anti-hypercalcemic / hypocalcemic action, originally identified in fish. The hormone in mammals is expressed in virtually all tissues and regulates diverse biological functions, acting as an autocrine / paracrine factor. Many evidences demonstrate that STC1 is able to regulate bone development. During embryogenesis the STC1 is expressed in early stages of mesenchymal condensation and thereafter remains restricted to preosteoblast and mature osteoblast. Furthermore, STC1 stimulates bone mineralization by increasing the phosphate transporter expression and osteopontin, a sialoglycoprotein involved in bone mineralization. Adult stem cells currently symbolize the most accessible source of stem cells used in cell therapy and tissue engineering. Adipose tissue contains a population of biological cells clinically interesting called adipose derived stem cells (ASC). Currently, the ASCs are the best source of adult stem cells and can be harvested using minimally invasive procedures. A large number of studies had shown osteogenic potential of these cells, however, it is still a challenge to understand the mechanisms involved in osteogenic differentiation from ASCs This study demonstrated that 7-day preosteoblast in the presence of 50 ng / ml STC1 significantly increased gene and protein expression of osteogenic markers: alkaline phosphatase (ALP), runt related gene 2 (RUNX2), and osteopontin (OPN ). Also, there was an increase in the enzymatic activity of the ALP, possibly related to both gene and protein expression. Furthermore, STC1 modulates pAkt / pGSK3-β / βcatenina signaling in 7-day preosteoblast, suggesting that the STC1 effects on the osteogenesis is mediated by this pathway. The neuroendocrine peptide CGRP (calcitonin gene related peptide) has similarities to STC1 and plays an important role in the early stages of osteoblast differentiation. The active CGRP receptor form a dimer with the receptor activity-modifying protein 1 (RAMP1). To elucidate the involvement of STC1 in signaling pathways related to calcitonin receptors, it was investigated the STC1 effect on peptide receptor modulating the calcitonin gene related peptide (CGRP) and the calcitonin receptor (CTR) in 7-day preosteoblast, and in Hek 293 cells transfected with CALCRL / RAMP1 and CTR The STC1 did not change the expression of genes CALCRL and ramp1 during osteoblastogenesis but modified the plasma membrane spatial distribution of 10 CALCRL/RAMP1 in preosteoblast. Besides the effect on CGRP signaling, STC1 inhibited the calcitonin signaling by decreasing cAMP production in cells transfected with CTR. The STC1 did not alter intracellular calcium levels and ATP. These results indicated that STC1 does not act on the same receptors for calcitonin and CGRP, but modulates the action of these peptides. Studies on the effects of STC1 in different signaling pathways are necessary for understanding the mechanisms underlying the STC1 ability in enhancing osteoblastogenesis from hASCs.
57

Welding with Low Alloy Steel Filler Metal of X65 Pipes Internally Clad with Alloy 625: Application in Pre-Salt Oil Extraction

O'Brien, Evan Daniel 28 December 2016 (has links)
No description available.
58

Theoretical modeling of molar volume and thermal expansion

Lu, Xiao-Gang January 2005 (has links)
<p>Combination of the Calphad method and theoretical calculations provides new possibilities for the study of materials science. This work is a part of the efforts within the CCT project (Centre of Computational Thermodynamics) to combine these methods to facilitate modeling and to extend the thermodynamic databases with critically assessed volume data. In this work, the theoretical calculations refer to first-principles and Debye-Grüneisen calculations. The first-principles (i.e. ab initio) electronic structure calculations, based on the Density- Functional Theory (DFT), are capable of predicting various physical properties at 0 K, such as formation energy, volume and bulk modulus. The ab initio simulation software, VASP, was used to calculate the binding curves (i.e. equation of state at 0 K) of metallic elements, cubic carbides and nitrides. From the binding curves, the equilibrium volumes at 0 K were calculated for several metastable structures as well as stable structures. The vibrational contribution to the free energy was calculated using the Debye-Grüneisen model combined with first-principles calculations. Two different approximations for the Grüneisen parameter, γ, were used in the Debye-Grüneisen model, i.e. Slater’s and Dugdale-MacDonald’s expressions. The thermal electronic contribution was evaluated from the calculated electronic density of states. The calculated thermal expansivities for metallic elements, cubic carbides and nitrides were compared with Calphad assessments. It was found that the experimental data are within the limits of the calculations using the two approximations for γ. By fitting experimental heat capacity and thermal expansivity around Debye temperatures, we obtained optimal Poisson’s ratio values and used them to evaluate Young’s and Shear moduli. In order to reach a reasonable agreement with the experiments, it is necessary to use the logarithmic averaged mass of the constitutional atoms. The agreements between the calculations and experiments are generally better for bulk modulus and Young’s modulus than that for shear modulus. A new model describing thermodynamic properties at high pressures was implemented in Thermo-Calc. The model is based on an empirical relation between volume and isothermal bulk modulus. Pure Fe and solid MgO were assessed using this model. Solution phases will be considered in a future work to check the model for compositional dependence.</p>
59

Theoretical modeling of molar volume and thermal expansion

Lu, Xiao-Gang January 2005 (has links)
Combination of the Calphad method and theoretical calculations provides new possibilities for the study of materials science. This work is a part of the efforts within the CCT project (Centre of Computational Thermodynamics) to combine these methods to facilitate modeling and to extend the thermodynamic databases with critically assessed volume data. In this work, the theoretical calculations refer to first-principles and Debye-Grüneisen calculations. The first-principles (i.e. ab initio) electronic structure calculations, based on the Density- Functional Theory (DFT), are capable of predicting various physical properties at 0 K, such as formation energy, volume and bulk modulus. The ab initio simulation software, VASP, was used to calculate the binding curves (i.e. equation of state at 0 K) of metallic elements, cubic carbides and nitrides. From the binding curves, the equilibrium volumes at 0 K were calculated for several metastable structures as well as stable structures. The vibrational contribution to the free energy was calculated using the Debye-Grüneisen model combined with first-principles calculations. Two different approximations for the Grüneisen parameter, γ, were used in the Debye-Grüneisen model, i.e. Slater’s and Dugdale-MacDonald’s expressions. The thermal electronic contribution was evaluated from the calculated electronic density of states. The calculated thermal expansivities for metallic elements, cubic carbides and nitrides were compared with Calphad assessments. It was found that the experimental data are within the limits of the calculations using the two approximations for γ. By fitting experimental heat capacity and thermal expansivity around Debye temperatures, we obtained optimal Poisson’s ratio values and used them to evaluate Young’s and Shear moduli. In order to reach a reasonable agreement with the experiments, it is necessary to use the logarithmic averaged mass of the constitutional atoms. The agreements between the calculations and experiments are generally better for bulk modulus and Young’s modulus than that for shear modulus. A new model describing thermodynamic properties at high pressures was implemented in Thermo-Calc. The model is based on an empirical relation between volume and isothermal bulk modulus. Pure Fe and solid MgO were assessed using this model. Solution phases will be considered in a future work to check the model for compositional dependence.
60

Thermodynamic modelling and assessment of some alumino-silicate systems

Mao, Huahai January 2005 (has links)
Alumino-silicate systems are of great interest for materials scientists and geochemists. Thermodynamic knowledge of these systems is useful in steel and ceramic industries, and for understanding geochemical processes. A popular and efficient approach used to obtain a self-consistent thermodynamic dataset is called CALPHAD. It couples phase diagram information and thermochemical data with the assistance of computer models. The CALPHAD approach is applied in this thesis to the thermodynamic modelling and assessments of the CaO-Al2O3-SiO2, MgO-Al2O3-SiO2 and Y2O3-Al2O3-SiO2 systems and their subsystems. The compound energy formalism is used for all the solution phases including mullite, YAM, spinel and halite. In particular, the ionic two sub-lattice model is applied to the liquid solution phase. Based both on recent experimental investigations and theoretical studies, a new species, AlO2-1, is introduced to model liquid Al2O3. Thus, the liquid model corresponding for a ternary Al2O3-SiO2-M2Om system has the formula (Al+3,M+m)P (AlO2-1,O-2, SiO4-4,SiO20)Q, where M+m stands for Ca+2, Mg+2 or Y+3. This model overcomes the long-existing difficulty of suppressing the liquid miscibility gap in the ternary systems originating from the Al2O3-free side during the assessments. All the available and updated experimental information in these systems are critically evaluated and finally a self-consistent thermodynamic dataset is achieved. The database can be used along with software for Gibbs energy minimization to calculate any type of phase diagram and all thermodynamic properties. Various phase diagrams, isothermal and isoplethal sections, and thermochemical properties are presented and compared with the experimental data. Model calculated site fractions of species are also discussed. All optimization processes and calculations are performed using the Thermo-Calc software package. / QC 20100607

Page generated in 0.0549 seconds