944 resultados para polybutadiene rubber ( BR)
Resumo:
La recherche sur la conception de nouveaux matriaux, dits intelligents, est en constant progrs depuis plus de 30 ans. Historiquement, les premiers matriaux utiliss et transforms par lhomme taient le bois, les minraux et ses drivs (pierre, mtaux, etc.). Cest la fin du 19e sicle que la synthse des polymres organiques et inorganiques ainsi que leurs utilisations se dvelopprent. Ce progrs continue de nos jours. Ainsi, cest dans cette direction que cette thse fut rdige, ltude de polymres de coordination bass sur le cuivre(I). Elle sorchestra en six principales sections de recherche. La premire section, i.e. le chapitre 2 traite de la coordination de diffrents ligands monothiothers sur du CuX (X = I, Br) pour former plusieurs types de polymres de coordination (CPs). Ainsi, le CP 1D [(Me[indice infrieur 2]S)[indice infrieur 3]{Cu[indice infrieur 2]([mu]-I)[indice infrieur 2}][indice infrieur n] est obtenu quand CuI et Sme[indice infrieur 2] ragissent ensemble dans le n-heptane, alors quils entrainent la formation du CP 2D [(Me[indice infrieur 2]S) [indice infrieur 3] {Cu[indice infrieur 4]([mu]-I) [indice infrieur 4]}] [indice infrieur n] dans le MeCN. Ce dernier contient des units de construction secondaire (SBU; Secondary Building Units en anglais) en forme de cluster Cu[indice infrieur 4]I[indice infrieur 4] cubane partiellement ouvert . En faisant ragir le MeSEt avec du CuI, le CP 2D [(MeSEt) [indice infrieur 2]{Cu[indice infrieur 4] ([mu][indice infrieur 3]-I) [indice infrieur 2] ([mu][indice infrieur 2]-I) [indice infrieur 2]}(MeCN) [indice infrieur 2]] [indice infrieur n] contenant des SBUs de type Cu[indice infrieur 4]I[indice infrieur 4] cubanes en escalier a t isol dans MeCN, alors quils entrainent lobtention du polymre 1D [(MeSEt) [indice infrieur 3]{Cu[indice infrieur 4] ([mu][indice infrieur 3]-I) [indice infrieur 4]}] [indice infrieur n] dans le n-heptane contenant quant lui des clusters de types Cu[indice infrieur 4]I[indice infrieur 4] cubanes ferms . Alors que le traitement de MeSPr avec du CuI forme le CP 1D [(MeSPr) [indice infrieur 3]{Cu[indice infrieur 4] ([mu][indice infrieur 3]-I) [indice infrieur 4]}] [indice infrieur n], les composs [(L) [indice infrieur 4]{Cu[indice infrieur 4] ([mu][indice infrieur 3]-I) [indice infrieur 4]}] (L = EtSPr, Pr[indice infrieur 2]S) sont respectivement obtenus avec le EtSPr et le Pr[indice infrieur 2]S. partir du [indice suprieur i]Pr[indice infrieur 2]S et de CuI, le cluster [([indice suprieur i]Pr[indice infrieur 2]S) [indice infrieur 6]{Cu[indice infrieur 8] ([mu][indice infrieur 3]-I) [indice infrieur 3]}([mu][indice infrieur 4]-I) [indice infrieur 2]}] est obtenu alors que lon forme un CP 2D [(Cu[indice infrieur 3]Br[indice infrieur 3])(MeSEt) [indice infrieur 3]] [indice infrieur n] partir de CuBr et MeSEt dans lheptane. Ce dernier incorpore la fois des Cu([mu][indice infrieur 2]-Br) [indice infrieur 2]Cu rhombodriques et des SBUs de type Cu[indice infrieur 4]Br[indice infrieur 4] cubanes ouverts . Le MeSPr forme, quant lui avec le CuBr dans lheptane, le CP 1D [(Cu[indice infrieur 3]Br[indice infrieur 3])(MeSPr) [indice infrieur 3]] [indice infrieur n] qui, aprs recristallisation dans le MeCN, est converti en un CP 2D [(Cu[indice infrieur 5]Br[indice infrieur 5])([mu][indice infrieur 2]-MeSPr) [indice infrieur 3]] [indice infrieur n] incorporant des SBUs [(Cu[indice infrieur 5] ([mu][indice infrieur 4]-Br)([mu][indice infrieur 2]-Br)]. Les proprits de stabilits thermiques et photophysiques de ces matriaux ont aussi t reportes. Dans la section 2, i.e. au chapitre 3, les ractions entre des ligands dithiotherbutanes (1,4-bis(phnylthio)butane et 1,4-bis(cyclohexylthio)butane) avec CuX (X = Br, I) ont t tudies. En faisant ragir les CuX avec le 1,4-bis(cyclohexylthio)butane, dans le ratio (1:1), les CPs 1D, peu luminescents, isostructuraux [(Cu[indice infrieur 2]X[indice infrieur 2])([mu]-CyS(CH[indice infrieur 2]) [indice infrieur 4])SCy) [indice infrieur 2]] [indice infrieur n] (X = Br, I) sont obtenus. Inversement, quand CuI ragit avec 1,4-bis(phnylthio)butane, dans le ratio (2:1), il se forme le pralablement report CP 2D [(Cu[indice infrieur 4]I[indice infrieur 4])([mu]- PhS(CH[indice infrieur 2]) [indice infrieur 4])SPh) [indice infrieur 2]] [indice infrieur n], alors quavec le CyS(CH[indice infrieur 2]) [indice infrieur 4])SCy, un nouveau compos luminescent est obtenu, mais sa structure na pas pu tre rsolue.(1) Les caractrisations habituelles en photophysique et en stabilit thermique ont t menes sur ces matriaux. Dans la troisime section, i.e. dans le chapitre 4, les ractions de coordination de CuX (Br, I) sur les ligands dithiotherbutnes E-et Z-PhS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])SPh, E-et Z-pTolS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])S-pTol ont t compares. Quand les sels CuX ragissent avec E-PhS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])SPh les CP 2D [Cu[indice infrieur 2]X[indice infrieur 2]{[mu]-E-PhS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])SPh}[indice infrieur 2]] [indice infrieur n] (X = I, Br), composs isostructuraux, sont obtenus. Incorporant une structure sans-prcdente, ces rseaux sont forms partir de couches 2D en alternance ABAB, contenants des SBUs Cu[indice infrieur 2] ([mu][indice infrieur 2]-X) [indice infrieur 2] rhombodriques. Inversement, quand lisomre Z-PhS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])SPh ragit avec des sels de CuX, deux structures diffrentes sont obtenues : le CP 2D [Cu[indice infrieur 4] ([mu][indice infrieur 3]-I) [indice infrieur 4] ([mu]-Z-PhS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])SPh}[indice infrieur 2]] [indice infrieur n] contenant des SBUs de type cubane ferm et le complexe 0D [Cu[indice infrieur 2]Br[indice infrieur 2]{[mu]-Z-PhS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])SPh}[indice infrieur 2]]. De par la raction de E-pTolS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])S-pTol avec CuI, le CP 2D [{Cu([mu][indice infrieur 3]-I)} [indice infrieur 2] ([mu]-E-pTolS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])S-pTol)]n contenant des rubans parallles en escalier est obtenu, alors que la structure issue de CuBr na pas pu tre rsolue. Finalement, quand CuX ragit avec Z-pTolS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])S-pTol, les CPs 2D iso-structuraux [Cu[indice infrieur 2]X[indice infrieur 2]{[mu]-Z-pTolS(CH[indice infrieur 2]CH=CHCH[indice infrieur 2])S-pTol}[indice infrieur 2]] (X = I, Br) sont forms. Dans ce cas, contrairement, aux premires structures obtenues, les couches de ces CPs sont composes de grilles incorporant des SBUs rhombodriques Cu[indice infrieur 2] ([mu][indice infrieur 2]-X) [indice infrieur 2] dont les distances CuCu sont identiques dune couche lautre. Les caractrisations habituelles en photophysique et en stabilits thermiques ont t menes sur ces matriaux. De plus, des calculs thoriques ont t raliss afin de mieux comprendre les proprits photophysiques de ces composs. La quatrime section, i.e. le chapitre 5, traite des ractions de CuX (Br, I, Cl) sur des ligands dithiotherbutynes (1,4-bis(pTolthio)but-2-yne et 1,4-bis(benzylthio)but-2-yne. Quand CuBr ragit avec 1,4-bis(pTolthio)but-2-yne, le CP 1D [{Cu([mu][indice infrieur 2]-Br) [indice infrieur 2]Cu}([mu]-pTolSCH[indice infrieur 2]CCCH[indice infrieur 2]S-pTol) [indice infrieur 2]] [indice infrieur n] est obtenu, alors que le CP 2D [{Cu[indice infrieur 4] ([mu][indice infrieur 3]-I) [indice infrieur 4]}([mu]-pTolSCH[indice infrieur 2]CCCH[indice infrieur 2]S-pTol) [indice infrieur 2]] [indice infrieur n], pralablement report, est form.(2) La raction des sels CuI et CuCl avec 1,4-bis(benzylthio)but-2-yne engendre la formation de complexes isomorphes 0D [{Cu([mu][indice infrieur 2]-X) [indice infrieur 2]Cu}([mu]-PhCH[indice infrieur 2]SCH[indice infrieur 2]CCCH[indice infrieur 2]SCH[indice infrieur 2]Ph) [indice infrieur 2]] (X = I, Br). Contrairement lutilisation de CuCl, qui avec PhCH[indice infrieur 2]SCH[indice infrieur 2]CCCH[indice infrieur 2]SCH[indice infrieur 2]Ph forme le CP 2D [{Cu[indice infrieur 2] ([mu][indice infrieur 2]-Cl)([mu] [indice infrieur 3]-Cl)}([mu]-PhCH[indice infrieur 2]SCH[indice infrieur 2]CCCH[indice infrieur 2]SCH[indice infrieur 2]Ph)] [indice infrieur n]. Notons que ce CP prsente des proprits de photophysique peu communes pour un driv chlor, car il met de la lumire autour de 600 nm. La cinquime section, i.e. le chapitre 6, traite des ractions de CuI avec PhS(CH[indice infrieur 2]) [indice infrieur 8]SPh et pTolS(CH[indice infrieur 2]) [indice infrieur 8]S-pTol qui gnrent respectivement les CPs luminescents 1D [Cu[indice infrieur 4]I[indice infrieur 4]{[mu][indice infrieur 2]-PhS(CH[indice infrieur 2]) [indice infrieur 8]SPh}[indice infrieur 2]] [indice infrieur n] et 2D [Cu8I8{[mu]2-pTolS(CH2)8S-pTol}3(MeCN)2]n. Le CP 2D [Cu8I8{[mu]2-pTolS(CH2)8S-pTol}3 (MeCN)2]n prsente un rseau qui navait jamais t rencontr dans la littrature auparavant, c.--d., des couches de polymre construites partir de deux cubanes ferms ponts ensemble par un rhombodre comme SBUs. Leurs proprits physiques et de stabilits thermiques ont t tudies et prsentent quelques diffrences notables. La sixime section, i.e. le chapitre 7, traite des ractions entre CuI avec le ligand flexible pTolS(CH[indice infrieur 2]) [indice infrieur 8]S-pTol dans le MeCN ou EtCN et p-[indice suprieur t]BuC[indice infrieur 6]H[indice infrieur 4]S(CH[indice infrieur 2]) [indice infrieur 8]SC[indice infrieur 6]H[indice infrieur 4]-p-[indice suprieur t]Bu L2 dans EtCN. Les synthses issues de pTolS(CH[indice infrieur 2]) [indice infrieur 8]S-pTol permettent lobtention de CPs 2D [Cu[indice infrieur 8]I[indice infrieur 8]{pTolS(CH[indice infrieur 2]) [indice infrieur 8]S-pTol}[indice infrieur 3] (solvant) [indice infrieur 2]] [indice infrieur n] (1MeCN et 1EtCN) contenant des nuds de connexion de type Cu[indice infrieur 8]I[indice infrieur 8]. Par opposition, lutilisation du ligand p-[indice suprieur t]BuC[indice infrieur 6]H[indice infrieur 4]S(CH[indice infrieur 2]) [indice infrieur 8]SC[indice infrieur 6]H[indice infrieur 4]-p-[indice suprieur t]Bu dans EtCN entraine la formation dun CP 1D [Cu[indice infrieur 4]I[indice infrieur 4]{p-[indice suprieur t]BuC[indice infrieur 6]H[indice infrieur 4]S(CH[indice infrieur 2]) [indice infrieur 8]SC[indice infrieur 6]H[indice infrieur 4]-p-[indice suprieur t]Bu}[indice infrieur 2] (EtCN) [indice infrieur 2]] [indice infrieur n] incorporant les SBUs de type cubane ferm. Les CPs 2D 1MeCN et 1EtCN, contrairement 2EtCN, prsentent lhabilit de pouvoir perdre le solvant initialement incorpor dans leur structure sous vide et de le readsorber ou dadsorber un autre solvant, chose qui peut tre suivie laide de la variation de la luminescence, la stabilit thermique, ou encore par diffraction des rayons X sur poudre. La septime section, i.e. le chapitre 8 traite des ractions, une fois encore, entre un ligand dithiother, contenant un pont flexible butane (EtS(CH[indice infrieur 2]) [indice infrieur 4]SEt) et les sels CuX (X = I, Br). Dans ce cas, il se forme avec le CuI un CP luminescent 2D [Cu[indice infrieur 4]I[indice infrieur 4]{[mu]-EtS(CH[indice infrieur 2]) [indice infrieur 4]SEt}[indice infrieur 2]] [indice infrieur n], alors quil gnre avec CuBr, le CP 3D [(Cu[indice infrieur 2]Br[indice infrieur 2]){[mu]-EtS(CH[indice infrieur 2]) [indice infrieur 4]SEt}][indice infrieur n] faiblement luminescent, construit sur des couches en parallle pontes par les soufres doublement n-donneurs. Il est intressant de remarquer quune migration de lnergie dexcitation se produit dans le CP 3D (driv brom) contrairement au CP 2D (driv iod) sous excitation de haute intensit. Trs peu dexemples prsentent ce type de processus parmi tous les CPs ( < 10). Pour conclure, les ractions entre les sels CuX (X = Cl, Br, I) avec des ligands thiothers de types diffrents (mono-, di-thio, rigide ou flexible) peuvent offrir des matriaux de structures variables (CP 0D, 1D, 2D, 3D avec et sans cavits) prsentant leurs propres spcificits (luminescence, stabilit thermique, adsorption de gaz, solvatochromisme, etc.). Le rsultat le plus important noter, en comparaison avec la littrature est, quil est trs difficile, voire impossible, de pouvoir prdire la dimensionnalit, la structure et les proprits dont rsultera la coordination des ligands thiothers sur des sels de CuX (X = Cl, Br, I). Par consquent, de nombreuses combinaisons et tudes restent encore tre menes pour mieux comprendre ces matriaux et trouver la, ou les meilleures combinaisons possibles pour concevoir des MOFs luminescents partir de CuX.
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Ecomorphology is a science based on the idea that morphological differences among species could be associated with distinct biological and environmental pressures suffered by them. These differences can be studied employing morphological and biometric indexes denominated Ecomorphological attributes , representing standards that express characteristics of the individual in relation to its environment, and can be interpreted as indicators of life habits or adaptations suffered due its occupation of different habitats. This work aims to contribute for the knowledge of the ecomorphology of the Brazilian marine ichthyofauna, specifically from Galinhos, located at Rio Grande do Norte state. 10 different species of fish were studied, belonging the families Gerreidae (Eucinostomus argenteus), Haemulidae (Orthopristis ruber,Pomadasyscorvinaeformis,Haemulonaurolineatum,Haemulonplumieri,Haemulonsteindachneri), Lutjanidae (Lutjanus synagris), Paralichthyidae (Syaciummicrurum), Bothidae (Bothus ocellatus) and Tetraodontidae (Sphoeroidestestudineus), which were obtained during five collections, in the period time of September/2004 to April/2005, utilizing three special nets. The ecomorphological study was performed at the laboratory. Eight to ten samples of each fish specie were measured. Fifteen morphological aspects were considered to calculate twelve ecomorphological attributes. Multivariate statistical analysis methods such as Principal Component Analysis (PCA) and Cluster Analysis were done to identify ecmorphological patterns to describe the data set obtained. As results, H.aurolineatumwas the most abundant specie found (23,03%) and S.testudineusthe less one with 0,23%. The 1st Principal component showed variation of 60,03% with influence of the ecomorphological attribute related to body morphology, while the 2nd PC with 23,25% variation had influence of the ecomorphological attribute related to oral morphology. The Cluster Analiysis promoted the identification of three distinct groups Perciformes, Pleuronectiformes and Tetraodontiformes. Based on the obtained data, considering morphological characters differences among the species studied, we suggest that all of them live at the medium (E.argenteus,O.rubber, P.corvinaeformis,H.aurolineatum,H.plumieri,H.steindachneri,L.synagris) and bottom (S.micrurum,B.ocellatus,S.testudineus) region of column water.
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Chitin is an important structural component of the cellular wall of fungi and exoskeleton of many invertebrate plagues, such as insects and nematodes. In digestory systems of insects it forms a named matrix of peritrophic membrane. One of the most studied interaction models protein-carbohydrate is the model that involves chitin-binding proteins. Among the involved characterized domains already in this interaction if they detach the hevein domain (HD), from of Hevea brasiliensis (Rubber tree), the R&R consensus domain (R&R), found in cuticular proteins of insects, and the motif called in this study as conglicinin motif (CD), found in the cristallography structure of the β-conglicinin bounded with GlcNac. These three chitin-binding domains had been used to determine which of them could be involved in silico in the interaction of Canavalia ensiformis and Vigna unguiculata vicilins with chitin, as well as associate these results with the WD50 of these vicilins for Callosobruchus maculatus larvae. The technique of comparative modeling was used for construction of the model 3D of the vicilin of V. unguiculata, that was not found in the data bases. Using the ClustalW program it was gotten localization of these domains in the vicilins primary structure. The domains R&R and CD had been found with bigger homology in the vicilins primary sequences and had been target of interaction studies. Through program GRAMM models of interaction ( dockings ) of the vicilins with GlcNac had been gotten. The results had shown that, through analysis in silico, HD is not part of the vicilins structures, proving the result gotten with the alignment of the primary sequences; the R&R domain, although not to have structural similarity in the vicilins, probably it has a participation in the activity of interaction of these with GlcNac; whereas the CD domain participates directly in the interaction of the vicilins with GlcNac. These results in silico show that the amino acid number, the types and the amount of binding made for the CD motif with GlcNac seem to be directly associates to the deleterious power that these vicilins show for C. maculatus larvae. This can give an initial step in the briefing of as the vicilins interact with alive chitin in and exert its toxic power for insects that possess peritrophic membrane
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The failure of materials is always an unwelcome event for several reasons: human lives are put in danger, economic losses, and interference in the availability of products and services. Although the causes of failures and behaviour of materials can be known, the prevention of such a condition is difficult to be guaranteed. Among the failures, wear abrasion by the low voltage is the kind of failure that occurs in more equipment and parts industry. The Plants Sucroalcooleiras suffer significant losses because of such attrition, this fact that motivated their choice for the development of this work. For both, were considered failures in the swing hammers desfibradores stopped soon after the exchange provided in accordance with tonnage of cane processed, then were analyzed by the level of wear testing of rubber wheel defined by the standard ASTM G65-91.The failures were classified as to the origin of the cause and mechanism, moreover, were prepared with samples of welding procedures according to ASME code, sec. IX as well, using the technique of thermal spraying to analyze the performance of these materials produced in laboratories, and compares them with the solder used in the plant. It was observed that the bodies-of-proof prepared by the procedure described as welding, and the thermal spraying the results of losing weight have been minimized significantly compared to the preparations in the plant. This is because the use of techniques more appropriate and more controlled conditions of the parameters of welding. As for the thermal spraying, this technique has presented a satisfactory result, but requires the use of these coatings in the best condition for real affirmation of the results
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The low tenacity presented by the Portland cement pastes used in the oil wells cementation has been motivating several researches with attention focused on alternative materials. Additives have been developed to generate flexible pastes with mechanical resistance capable to support the expansions and retractions of the metallic covering of the wells that submit to the steam injection, technique very used to increase the recovery factor in oil reservoirs with high viscosity. A fresh paste with inadequate rheological behavior may commit the cementation process seriously, involving flaws that affect the performance of the paste substantially in the hardened state. This work proposes the elaboration and the rheological analysis of Portland cement pastes with addition of residues of rubber tire in several proportions, with the aim of minimizing the damages provoked in the hem cementing of these wells. By thermogravimetric analysis, the particles of eraser that go by the sieve of 0,5mm (35 mesh) opening and treated superficially with NaOH solution of 1 mol/L presented appropriate thermal resistance for wells that submit to thermal cyclic. The evaluation of the study based on the results of the rheological analysis of the pastes, complemented by the mechanical analysis, thickening, stability, tenor of free water and filtrate loss, being used as parameter a paste reference, without rubber addition. The results showed satisfactory rheology, passive of few corrections; considerable loss of mechanical resistance (traction and compression), compensated by earnings of tenacity, however with established limits for its application in oil wells; satisfactory stability, free water and thickening time
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Although already to exist alternative technique and economically viable for destination of used tires, quantitative data on properties of constructive elements that use the rubber waste as aggregate still are restricted. In the present work, the waste proceeding from industry of retreading as material for manufacture of composite destined to the production of constructive elements was considered. Mechanical and thermal properties of mortar had been analyzed Portland cement with addition of waste without treatment, in the ratios of 10%, 20% and 30% in mass in relation to the mass of the cement, substituting the aggregate in the trace in mortar 1:5 mass cement and sand. The size of the used residue varied between 0,30mm and 4,8mm (passing in the bolter 4,8mm and being restrained in the one of 0,30mm), being it in the formats fibers and granular. The influences of the size and the percentage of residue added to the mortar (in substitution to the aggregate) in the thermal and mechanical properties had been considered. Assays of body-of-test in thestates had been become fullfilled cool (consistency index) and hardened (absorption of water for capillarity, strength the compression, traction and strength flexural). The work is centralized in the problem of the relation thermal performance /strength mechanics of used constructive systems in regions of low latitudes (Been of the Piau), characterized for raised indices of solar radiation.
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Portland-polymers composites are promising candidates to be used as cementing material in Northeastern oil wells of Brazil containing heavy oils submitted to steam injection. In this way, it is necessary to evaluate its degradation in the commonly acidizind agents. In addition, to identify how aggressive are the different hostile environments it is an important contribution on the decision of the acidic systems to be used in. It was investigated the performance of the Portland-polymer composites using powdered polyurethane, aqueous polyurethane, rubber tire residues and a biopolymer, those were reinforced with polished carbon steel SAE 1045 to make the electrochemical measurements. HCl 15,0 %, HCl 6,0 % + HF 1,5 % (soft mud acid), HCl 12,0 % + HF 3,0 % (regular mud acid) and HAc 10 % + HF 1,5 % were used as degrading environment and electrolytes. The more aggressive acid solution to the plain Portland hardened cement paste was the regular mud acid, that showed loss of weight around 23.0 %, followed by the soft mud acid, the showed 11.0 %, 15.0 % HCl with 7,0 % and, at last the 10.0 % HAc plus HF 1.5 % with just 1.0 %. The powdered polyurethane-composite and the aqueous polyurethane one showed larger durability, with reduction around 87.0 % on the loss of weight in regular mud acid. The acid attack is superficial and it occurs as an action layer, where the degraded layer is responsible for the decrease on the kinetic of the degrading process. This behavior can be seen mainly on the Portland- aqueous polyurethane composite, because the degraded layer is impregnated with chemically modified polymer. The fact of the acid attack does not have influence on the compressive strength or fratography of the samples, in a general way, confirms that theory. The mechanism of the efficiency of the Portland-polymers composites subjected to acid attack is due to decreased porosity and permeability related with the plain Portland paste, minor quantity of Ca+2, element preferentially leached to the acidic solution, wave effect and to substitute part of the degrading bulk for the polymeric one. The electrolyte HAc 10 % + HF 1,5 % was the least aggressive one to the external corrosion of the casing, showing open circuit potentials around +250 mV compared to -130 mV to the simulated pore solution to the first 24 hours immersion. This behavior has been performed for two months at least. Similar corrosion rates were showed between both of the electrolytes, around 0.01 μA.cm-2. Total impedance values, insipient arcs and big polarization resistance capacitive arcs on the Nyquist plots, indicating passivity process, confirm its efficiency. In this way, Portlandpolymers composites are possible solutions to be succeed applied to oilwell cementing concomitant submitted to steam injection and acidizing operation and the HAc 10,0 % + HF 1,5 % is the less aggressive solution to the external corrosion of the casing
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126 p. El contenido del captulo 3 est sujeto a confidencialidad.
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Dissertao de mest. em Aquacultura, Faculdade de Cincias do Mar e do Ambiente, Univ. do Algarve, 2001
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O intercmbio teve como objetivo adaptar de forma interativa tecnologias e conhecimentos em manejo de aaizais nativos aos indgenas das Aldeias Tukay e Ahum, em parcelas demonstrativas instaladas prximas a BR-156, nas Terras Indgenas de Oiapoque, no Estado do Amap. No ?manejo de mnimo impacto de aaizais nativos? recomenda-se uma densidade de 400 touceiras/ha de aaizeiros e cada touceira com cinco estipes adultos (produzindo frutos), quatro estipes jovens e trs perfilhos, com altura mxima de 14 m. Para as demais espcies, 250 plantas por hectare, sendo 60% de finas (CAP≥15≤60 cm), 20% de mdias (CAP>60≤140 cm) e 20% de grossas (CAP>140 cm). Alm disso, que a distribuio espacial, tanto dos aaizeiros quanto das dicotiledneas arbreas, seja a mais uniforme possvel, para que a luz solar e a reciclagem dos nutrientes possam beneficiar todas as plantas existentes no aaizal. Os resultados devero aparecer nos prximos anos com aumento na produo de frutos de aa e na diversidade florestal do aaizal.
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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
Microclimate, development and productivity of robusta coffee shaded by rubber trees and at full sun.
Resumo:
Existem poucos estudos sobre arborizao de caf conilon com seringueira. Objetivou-se avaliar o microclima, desenvolvimento e produtividade do cafeeiro conilon cultivado a pleno sol e sob sombreamento proporcionado pela seringueira. O experimento foi composto por uma lavoura de caf conilon (Coffea canephora), cultivada a pleno sol e outra lavoura de caf consorciada com seringueira (Hevea brasiliensis). A seringueira e o cafeeiro foram plantados no sentido Leste/Oeste, em Jaguar, Esprito Santo, Brasil. Avaliou-se a luminosidade, temperatura e umidade relativa do ar, concentrao foliar de nutrientes, medio dos interndios dos ramos plagiotrpicos e ortotrpicos, rea foliar, ndice relativo de clorofila, e a produtividade do cafeeiro. O sombreamento influenciou diretamente no microclima, reduzindo a temperatura do ar no vero e no inverno e aumentando a umidade relativa. A luminosidade no vero teve uma reduo media de 905 lumens ft-2 ao longo de todo dia, equivalente a 72,49%, e no inverno de 1665 lumens ft-2, equivalente a 88,04%. O sombreamento proporcionou maior estiolamento dos ramos plagiotrpicos e ortotrpicos, bem como maior expanso foliar. A concentrao foliar de Fe e Mn foram maiores no cafeeiro arborizado. A clorofila b e total estimada foram maior no cafeeiro cultivado a pleno sol. O denso sombreamento oferecido pela seringueira nas condies estudadas proporcionou perdas na produtividade do cafeeiro, contudo, ocorre a formao da seringueira.
Resumo:
Dissertao (mestrado)Universidade de Braslia, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2016.
Resumo:
Ecomorphology is a science based on the idea that morphological differences among species could be associated with distinct biological and environmental pressures suffered by them. These differences can be studied employing morphological and biometric indexes denominated Ecomorphological attributes , representing standards that express characteristics of the individual in relation to its environment, and can be interpreted as indicators of life habits or adaptations suffered due its occupation of different habitats. This work aims to contribute for the knowledge of the ecomorphology of the Brazilian marine ichthyofauna, specifically from Galinhos, located at Rio Grande do Norte state. 10 different species of fish were studied, belonging the families Gerreidae (Eucinostomus argenteus), Haemulidae (Orthopristis ruber,Pomadasyscorvinaeformis,Haemulonaurolineatum,Haemulonplumieri,Haemulonsteindachneri), Lutjanidae (Lutjanus synagris), Paralichthyidae (Syaciummicrurum), Bothidae (Bothus ocellatus) and Tetraodontidae (Sphoeroidestestudineus), which were obtained during five collections, in the period time of September/2004 to April/2005, utilizing three special nets. The ecomorphological study was performed at the laboratory. Eight to ten samples of each fish specie were measured. Fifteen morphological aspects were considered to calculate twelve ecomorphological attributes. Multivariate statistical analysis methods such as Principal Component Analysis (PCA) and Cluster Analysis were done to identify ecmorphological patterns to describe the data set obtained. As results, H.aurolineatumwas the most abundant specie found (23,03%) and S.testudineusthe less one with 0,23%. The 1st Principal component showed variation of 60,03% with influence of the ecomorphological attribute related to body morphology, while the 2nd PC with 23,25% variation had influence of the ecomorphological attribute related to oral morphology. The Cluster Analiysis promoted the identification of three distinct groups Perciformes, Pleuronectiformes and Tetraodontiformes. Based on the obtained data, considering morphological characters differences among the species studied, we suggest that all of them live at the medium (E.argenteus,O.rubber, P.corvinaeformis,H.aurolineatum,H.plumieri,H.steindachneri,L.synagris) and bottom (S.micrurum,B.ocellatus,S.testudineus) region of column water.
