998 resultados para indirizzo :: 122 :: Materiali


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Il presente lavoro di tesi è finalizzato all'ottimizzazione della formulazione iniziale e delle condizioni di stagionatura per ottenere un materiale utilizzabile come refrattario in applicazioni che richiedono elevate temperature di esposizione. L’interesse della ricerca scientifica verso questa nuova classe di materiali nasce dai vantaggi ambientali ed economici che essi possono fornire. Inoltre, le buone proprietà di resistenza e stabilità termica evidenziate dagli studi condotti negli ultimi anni inducono a sperimentare l’impiego dei materiali geopolimerici in sostituzione dei materiali refrattari o cementiferi attualmente in commercio. A tal fine sono state determinate le caratteristiche fisico-meccaniche, microstrutturali e termiche di matrici geopolimeriche additivate con scarti refrattari. Lo studio svolto, si può suddividere in tre fasi successive. Inizialmente sono state ottimizzazione le formulazioni geopolimeriche. Successivamente i prodotti ottenuti sono stati oggetto di caratterizzazione fisico-meccanica, microstrutturale e termica. Tali caratterizzazioni sono state eseguite attraverso: analisi al microscopio ottico, assorbimento di acqua, determinazione della densità geometrica, prove ultrasoniche per la determinazione dell’omogeneità del materiale, resistenza meccanica a compressione, diffrattometria ai raggi X (XRD), microscopio riscaldante, ciclo termico in muffola e analisi dilatometriche. Nella terza fase sono stati analizzati ed elaborati i risultati ottenuti, evidenziando le soddisfacenti proprietà di stabilità e resistenza termica. È stata inoltre effettuata una analisi economica preliminare evidenziando la competitività nel marcato del sistema geopolimerico studiato. Se a questo si aggiungono i considerevoli benefici ambientali dovuti al fatto che il prodotto è ottenuto con sostanze di recupero, non sarebbe sorprendente che in un futuro prossimo i geopolimeri possano essere largamente prodotti e commercializzati.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Mycobacterium leprae recA harbors an in-frame insertion sequence that encodes an intein homing endonuclease (PI-MleI). Most inteins (intein endonucleases) possess two conserved LAGLIDADG (DOD) motifs at their ctive center. A common feature of LAGLIDADG-type homing endonucleases is that they recognize and cleave the same or very similar DNA sequences. However, PI-MleI is distinctive from other members of the family of LAGLIDADG-type HEases for its modular structure with functionally separable domains for DNA-binding and cleavage, each with distinct sequence preferences. Sequence alignment analyses of PI-MleI revealed three putative LAGLIDADG motifs; however, there is conflicting bioinformatics data in regard to their identity and specific location within the intein polypeptide. To resolve this conflict and to determine the active-site residues essential for DNA target site recognition and double-stranded DNA cleavage, we performed site-directed mutagenesis of presumptive catalytic residues in the LAGLIDADG motifs. Analysis of target DNA recognition and kinetic parameters of the wild-type PI-MleI and its variants disclosed that the two amino acid residues, Asp(122) (in Block C) and Asp(193) (in functional Block E), are crucial to the double-stranded DNA endonuclease activity, whereas Asp(218) (in pseudo-Block E) is not. However, despite the reduced catalytic activity, the PI-MleI variants, like the wild-type PI-MleI, generated a footprint of the same length around the insertion site. The D122T variant showed significantly reduced catalytic activity, and D122A and D193A mutations although failed to affect their DNA-binding affinities, but abolished the double-stranded DNA cleavage activity. On the other hand, D122C variant showed approximately twofold higher double-stranded DNA cleavage activity, compared with the wild-type PI-MleI. These results provide compelling evidence that Asp(122) and Asp(193) in DOD motif I and II, respectively, are bona fide active-site residues essential for DNA cleavage activity. The implications of these results are discussed in this report.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Contenido: Verdad, historia y hermenéutica / Octavio N. Derisi – El lumen naturale en Santo Tomás y el essere ideale en Rosmini / William R. Darós – El constitutivo esencial de la persona / Octavio N. Derisi – Filosofía y desarrollo integral / Alberto Caturelli – La respuesta del hombre frente a lo existente : intuición y palabra / Osvaldo Francella – Notas y comentarios -- Bibliografía

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Líderes dos partidos reunidos com o Presidente da ANC decidem que não haverá recesso. Ulysses Guimarães(PMDB-SP) diz que seria danoso para o país e para as instituições a interrupção dos trabalhos da Constituinte. Bonifácio de Andrada(PMDB-MG) também é contra a paralisação dos trabalhos. Os líderes decidiram também que a Comissão de Sistematização não aceitará emendas que mudem o sentido das propostas já apresentadas pelas comissões. Bernardo Cabral(PMDB-AM) afirma que, segundo o Regimento, só cabem emendas de adequação. Mario Covas(PMDB-SP) explica que se for alterado o Regimento Interno, permitindo a apresentação de substitutivos, corre-se o risco de uma maioria parlamentar fazer a Constituição sozinha. Brandão Monteiro(PDT-RJ) diz que há uma distorção em relação aos trabalhos na Constituinte. Na sessão O Povo Pergunta, cidadão quer saber o que os constituintes estão fazendo em termos de justiça no Brasil. Paes Landim(PFL-PI) responde que, para acelerar os processos judiciais, a Assembleia Nacional Constituinte criou a figura dos juízes distritais que participarão dos julgamentos, com a presença de populares. Iram Saraiva(PMDB-GO) apresenta projeto de decisão a Comissão de Sistematização, para que seja possível a transmissão, pelas emissoras de televisão e de rádio, das votações da Constituinte. Terminou o prazo para apresentação de emendas, tendo sido recebidas mais de 5 mil.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Observations and laboratory experiments are summarised that examine the widely discussed issue of what Gammarus pulex feeds on. On the basis of the observations of the authors and data from the literature it can be noted that G. pulex belongs to the omnivorous organisms, but, depending on the conditions of subsistence, in its rations either plant or animal food can predominate.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

An investigation of a commercial oxide dispersion-strengthened steel (MA9561) irradiated with high energy Ne-ions to high doses at elevated temperatures is presented. Specimens of MA956 oxide dispersion strengthened steel together with a 9% Cr ferritic/martensitic steel, e.g., Grade 92 steel were irradiated simultaneously with 20Ne-ions (with 122 MeV) to successively increasing damage levels of 1, 5 and 10 dpa at the damage peak at 440 C and 570 C, respectively. Cross-sectional microstructures of the specimens were investigated with transmission electron microscopy. MA956 oxide dispersion strengthened steel showed a higher resistance to void swelling especially to void growth at the grain boundaries than the ferritic/martensitic steel, e.g., Grade 92 steel did, and thus exhibited a prominence for an application in the situation of a high He production at high temperatures. The suppression of the growth of voids especially at the grain boundaries in MA956 is ascribed to an enhanced recombination of the point defects and a trapping of Ne atoms at the interfaces of the yttrium–aluminum oxide particles and the matrix.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this paper the evolution of a time domain dynamic identification technique based on a statistical moment approach is presented. This technique can be used in the case of structures under base random excitations in the linear state and in the non linear one. By applying Itoˆ stochastic calculus, special algebraic equations can be obtained depending on the statistical moments of the response of the system to be identified. Such equations can be used for the dynamic identification of the mechanical parameters and of the input. The above equations, differently from many techniques in the literature, show the possibility of obtaining the identification of the dissipation characteristics independently from the input. Through the paper the first formulation of this technique, applicable to non linear systems, based on the use of a restricted class of the potential models, is presented. Further a second formulation of the technique in object, applicable to each kind of linear systems and based on the use of a class of linear models, characterized by a mass proportional damping matrix, is described.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Abstract. The possibility of using pumice aggregates for concrete in structural applications is discussed. In particular, the mix design of lightweight concrete for the manufacturing masonry units having proper strength, is discussed. Moreover, the design of the unit shape according to the technical code requirements and making it possible to arrange reinforcing steel bars is described. Reinforced bearing masonry walls, made with the concrete units in question, were manufactured and tests on the panels and on the designed units were carried out. For comparison, tests on concrete units and structural elements were carried out after the substitution of pumice aggregates with ordinary lightweight aggregates, proving that pumice can be considered an alternative to them. Sommario. L’uso della pomice come inerte per il confezionamento di calcestruzzo è poco diffuso sebbene essa sia stata usata già in antiche costruzioni come il Pantheon in Roma. In questo studio si affronta la possibilità di realizzare blocchi in calcestruzzo alleggerito con granuli di pomice. I blocchi, progettati e realizzati secondo le indicazioni normative correnti, sono stati usati per realizzare pannelli murari armati da sottoporre a carichi ciclici orizzontali. I risultati ottenuti, messi a confronto con quelli di pannelli realizzati con blocchi in cls alleggerito con argilla espansa, hanno mostrato la possibilità di utilizzare la pomice come validissima alternativa all’argilla espansa.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Abstract. The possibility of using pumice aggregates for concrete in structural applications is discussed. In particular, the mix design of lightweight concrete for the manufacturing masonry units having proper strength, is discussed. Moreover, the design of the unit shape according to the technical code requirements and making it possible to arrange reinforcing steel bars is described. Reinforced bearing masonry walls, made with the concrete units in question, were manufactured and tests on the panels and on the designed units were carried out. For comparison, tests on concrete units and structural elements were carried out after the substitution of pumice aggregates with ordinary lightweight aggregates, proving that pumice can be considered an alternative to them. Sommario. L’uso della pomice come inerte per il confezionamento di calcestruzzo è poco diffuso sebbene essa sia stata usata già in antiche costruzioni come il Pantheon in Roma. In questo studio si affronta la possibilità di realizzare blocchi in calcestruzzo alleggerito con granuli di pomice. I blocchi, progettati e realizzati secondo le indicazioni normative correnti, sono stati usati per realizzare pannelli murari armati da sottoporre a carichi ciclici orizzontali. I risultati ottenuti, messi a confronto con quelli di pannelli realizzati con blocchi in cls alleggerito con argilla espansa, hanno mostrato la possibilità di utilizzare la pomice come validissima alternativa all’argilla espansa.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Dissertação de Mestrado, Arquitetura Paisagista, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

Relevância:

20.00% 20.00%

Publicador:

Resumo:

One hundred twenty-two early-stage anal canal cancer patients (median age: 69 years) were treated with curative radiotherapy with (70 patients) or without (52 patients) concomitant chemotherapy. Median follow-up was 65 months (range: 4-238). At multivariate analysis, concomitant chemotherapy significantly improved local control (p = .007). Local control significantly influenced all considered endpoints, except the metastases free survival. The global rates of G3-G4 acute and late toxicity were 13.1% and 8.2%, respectively, and they were not increased by concomitant chemotherapy. Finally, concomitant chemotherapy is efficacious and safe in the treatment of T1-2N0 anal canal cancer patients and should be prospectively studied.