950 resultados para Sêneca, ca.4a.C.-ca.65d.C


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Estudos Literários - FCLAR

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Este trabalho investiga a presença da característica do furor em uma das tragédias do escritor romano Sêneca, qual seja, Phoenissae. Mais especificamente, o furor aqui analisado pertence à personagem Édipo, na primeira parte da tragédia. O furor é o atributo essencial para a transformação da personagem em monstro e essa transformação ocorre em todas as tragédias senequianas, sendo um traço estilístico do autor. Este trabalho também relaciona o furor à filosofia estoica de Sêneca, já que as suas personagens trágicas serviriam de exemplo de como o furor pode tirar do rumo a vida de uma pessoa desequilibrada

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Addition of NaOMe, NaOEt, or NaOPr(i) to dispironaphthalenone 1 resulted in the formation of diketones 4a-c and 5a-c. The structure assigned to 4a was confirmed by conversion to the known hemiacetal 3. Similar addition of carbon nucleophiles like diethyl malonate, dimethyl malonate, methyl cyanoacetate, and ethyl cyanoacetate afforded diketones 4d-g. Formation of these compounds has been rationalized.

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A series of chromium(III) complexes LCrCl3 (4a-c) bearing chelating 2,2'-iminodiphenyisulfide ligands [L = (2-ArMeC=NAr)(2)S] was synthesized in good yields from the corresponding ligands and CrCl3.(THF). Using modified methylaluminoxane (MMAO) as a cocatalyst, these complexes display moderate activities towards ethylene polymerization, and produce highly linear polyethylenes with broad molecular weight distribution. Polymer yields, catalyst activities and the molecular weights, as well as the molecular weight distributions of the polymers can be controlled over a wide range by the variation of the structures of the chromium(III) complexes and the polymerization parameters, such as Al/Cr molar ratio, reaction temperature and ethylene pressure.

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The reaction of [Cp*RhCl2](2) 1 with dilithium 1,2-dicarba-closo-dodecaborane(12)-1,2-dithiolate (a) and -diselenolate (b) afforded the 16-electron rhodium(III) half-sandwich complexes Cp*Rh[E2C2(B10H10)] [E=S (3a), Se (3b)]. The 18-electron trimethylphosphane rhodium(III) half-sandwiches Cp*Rh(PMe3)[E2C2(B10H10)] 4a-c were prepared from the reaction of Cp*RhCl2(PMe3) 2 with the same dichalcogenolates, including the ditelluride (c). The complexes 4a,b could also be obtained from the reaction of 3a,b with trimethylphosphane. The molecular geometry of 4b was determined by X-ray structural analysis. The 16-electron complexes 3 an monomeric in solution as shown by multinuclear magnetic resonance (H-1-, B-11-, C-13-, P-31- Se-77-, Rh-103-, Te-125-NMR). also in comparison with the data for the trimethylphosphane analogues 4a-c and for 6a in which the rhodium bears the eta(5)-1,3-C5H3 Bu-t(2) ligand. The Rh-103 nuclear shielding is reduced by 831 ppm (3a) and 1114 ppm (3b) with respect to the 18-electron complexes 4a,b. Similarly, the Se-77 nuclear shielding in 3b is reduced by 676.4 ppm with respect to that in 4b. (C) 1999 Elsevier Science S.A. All rights reserved.

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Resumen basado en el de la publicación

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From the carbolithiation of N,N-dimethylamino fulvene (3a) and different ortho-lithiated heterocycles (furan, thiophene and N-methylpyrrole), the corresponding lithium cyclopentadienide intermediate (4a-c) was formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl4 resulting in dimethylamino-functionalised titanocenes 5a-c. When these titanocenes were tested against LLC-PK cells, the IC50 values obtained were of 240, and 28 mu M for titanocenes 5a and 5b, respectively. The most cytotoxic titanocene 5c with an IC50 value of 5.5 mu M is found to be almost as cytotoxic as cis-platin, which showed an IC50 value of 3.3 mu M, when tested on the LLC-PK cell line, and titanocene 5c is approximately 400 times better than titanocene dichloride itself. (c) 2007 Elsevier B.V. All rights reserved.

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From the reaction of tert-butyl lithium or n-butyl lithium with N-methylpyrrole (1a), furan (1b) or 2-bromo-thiophen (1c), 2-N-methylpyrrolyl lithium (2a), 2-furyl lithium (2b) or 2-thiophenyl lithium (2c), respectively, was obtained. When reacted with 6-(2-N-methylpyrrolyl) fulvene (3a), 6-(2-furyl) fulvene (3b) or 6-(2-thiophenyl) fulvene (3c), the corresponding lithiated intermediates were formed (4a-c). Titanocenes (5a-c) were obtained through transmetallation with titanium tetrachloride. When these titanocenes were tested against pig kidney epithelial (LLC-PK) cells, inhibitory concentrations (IC50) of 32 mu M, 140 mu M, and 240 mu M, respectively, were observed. These values represent improved cytotoxicity against LLC-PK, compared to their ansa-analogues. (c) 2006 Elsevier B.V. All rights reserved.

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From the reaction of tert-butyl lithium with p-bromo-N,N-dimethylaniline (1a), p-bromoanisole (1b) or 1-bromo-3,5-dimethoxybenzene (1c), p-N,N-dimethylanityl lithium (2a), p-anisyl lithium (2b) or (3,5-dimethoxyphenyl) lithium (2c), respectively, were obtained. When reacted with 6-(p-N,N-dimethylanilinyl)fulvene (3a), 6-(p-methoxyphenyl)fulvene (3b) or 3,5-(dimethoxyphenyl)fulvene (3c), the corresponding lithiated intermediates were formed (4a-c). Titanium tetrachloride was added "in situ", obtaining titanocenes 5a-C, respectively. When these titanocenes were tested against pig kidney carcinoma (LLC-PK) cells, inhibitory concentrations (IC50) Of 3.8 x 10(-5) M, 4.5 x 10(-5) M, and 7.8 x 10(-5) M, respectively, were observed. These values represent improved cytotoxicity against LLC-PK, compared to their ansa-analogues. (c) 2006 Elsevier Ltd. All rights reserved.

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From the carbolithiation of 6-N,N-dimethylamino fulvene (3a) and different lithiated aryl species [p-N,N-dimethylanilinyl lithium, p-anisyl lithium and 4-lithio-benzo[1.3]dioxole (2a-c)], the corresponding lithium cyclopentadienide intermediates 4a-c were formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl4 resulting in dimethylamino-functionalised and aryl-substituted titanocenes 5a-c. When these titanocenes were tested against LLC-PK cells, the IC50 values obtained were of 54, 45 and 26 mu M for titanocenes 5a, b and c, respectively. The most cytotoxic titanocene in this paper, 5c is approximately 10 times less cytotoxic than cis-platin, which showed an IC50 value of 3.3 mu M, when tested on the LLC-PK cell line, but approximately 100 times better than titanocene dichloride. (C) 2007 Elsevier Masson SAS. All rights reserved.

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From the carbolithiation of 6-N,N-dimethylamino fulvene (3a) and different ortho-lithiated indole derivatives (5-methoxy-N-methylindole, N-methylindole and N,N-dimethylaminomethylindole), the corresponding lithium cyclopentadienide intermediate (4a-c) was formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl4 resulting in dimethylamino-functionalised titanocenes (5a-c). When these titanocenes were tested against LLC-PK cells, the IC50 values obtained were of 37 and 71 mu M for titanocenes 5a and 5b respectively. The most cytotoxic titanocene in this paper, 5c showed an IC50 value of 8.4 mu M is found to be almost as cytotoxic as cis-platin, which showed an IC50 value of 3.3 mu M, when tested on the LLC-PK cell line, and titanocene 5c is approximately 250 times better than titanocene dichloride itself.

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Purpose: To investigate the effect of airborne-particle abrasion or diamond bur preparation as pretreatment steps of non-carious cervical root dentin regarding substance loss and bond strength. Methods: 45 dentin specimens produced from crowns of extracted human incisors by grinding the labial surfaces with silicon carbide papers (control) were treated with one of three adhesive systems (Group 1A-C; A: OptiBond FL, B: Clearfil SE Bond, or C: Scotchbond Universal; n=15/adhesive system). Another 135 dentin specimens (n=15/group) produced from the labial, non-carious cervical root part of extracted human incisors were treated with one of the adhesive systems after either no pre-treatment (Group 2A-C), pre-treatment with airborne-particle abrasion (CoJet Prep and 50 µm aluminum oxide powder; Group 3A-C), or pre-treatment with diamond bur preparation (40 µm grit size; Group 4A-C). Substance loss caused by the pre-treatment was measured in Groups 3 and 4. After treatment with the adhesive systems, resin composite was applied and all specimens were stored (37°C, 100% humidity, 24 hours) until measurement of microshear bond strength (µSBS). Data were analyzed with a nonparametric ANOVA followed by Kruskal-Wallis and Wilcoxon rank sum tests (level of significance: alpha=0.05). Results: Overall substance loss was significantly lower in Group 3 (median: 19 µm) than in Group 4 (median: 113 µm; p<0.0001). There were no significant differences in µSBS between the adhesive systems (A-C) in Group 1, Group 3, and Group 4 (p>=0.133). In Group 2, OptiBond FL (Group 2A) and Clearfil SE Bond (Group 2B) yielded significantly higher µSBS than Scotchbond Universal (Group 2C; p<=0.032). For OptiBond FL and Clearfil SE Bond, there were no significant differences in µSBS between the ground crown dentin and the non-carious cervical root dentin regardless of any pre-treatment of the latter (both p=0.661). For Scotchbond Universal, the µSBS to non-carious cervical root dentin without pre-treatment was significantly lower than to ground crown dentin and to non-carious cervical root dentin pre-treated with airborne-particle abrasion or diamond bur preparation p<=0.014).

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Tetrazolo[1,5-a] pyridines/ 2-azidopyridines 1 undergo photochemical nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes 3, which react with alcohols to afford 2-alkoxy-1H-1,3-diazepines 4 (5), with secondary amines to 2-dialkylamino-5H-1,3-diazepines 16, sometimes via isolable 2-dialkylamino-1H-1,3-diazepines 15, and with water to 1,3-diazepin-2-ones 19. The latter are also obtained by elimination of isobutene or propene from 2-tert-butoxy- or 2-isopropoxy-1H-1,3-diazepines 4 or 5. 1,3-Diazepin-2-one 22B and 1,3-diazepin-4-one 24 were obtained from hydrolysis of the corresponding 4-chlorodiazepines. Diazepinones 19 undergo photochemical ring closure to diazabicycloheptenones 25 in high yields. The 2-alkoxy-1H-1,3-diazepines 4 and 5 interconvert by rapid proton exchange between positions N1 and N3. The free energies of activation for the proton exchange were measured by the Forsen - Hoffman method as DeltaGdouble dagger(298) = 16.2 +/- 0.6 kcal mol(-1) as an average for 4a - c in CD2Cl2, acetone-d(6), and methanol-d(4), and 14.1 +/- 0.6 kcal mol(-1) for 4c in acetone/D2O. The structures of 2-methoxy-5,6-bis( trifluoromethyl)-1H-1,3-diazepine 4k, 1,2-dihydro-4-diethylamino-5H-1,3-diazepin-2-one 22bB, and diazabicycloheptanone 26 were determined by X-ray crystallography. The former represents the first reported X-ray crystal structure of any monocyclic N-unsubstituted 1H-azepine.