980 resultados para N2 atmospheres


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En el presente artículo introducimos el concepto de “recuperación mutua” y proponemos las prácticas creativas como herramientas eficientesde recuperación de personas tanto con problemas de salud mental como con algún tipo de diversidad funcional. Frente al concepto clásico de “arte-terapia” nosotros proponemos el concepto de “práctica creativa” como más compatible con el modelo de “recuperación mutua”. Para ello, en primer lugar realizamos un breve repaso crítico a la relación del arte con la locura. Seguidamente, presentamos los conceptos hermanos de “recuperación” y “recuperación mutua” en el marco de lo que se ha venido a denominar las “health humanities”. Para finalizar, describimos dos prácticas creativas que en la actualidad están siendo evaluadas en España en el contexto de un proyecto de investigacióninternacional en recuperación mutua: Los seminarios creativos con personas con trastorno mental grave en el Museo de Arte Contemporáneo de Sevilla y el grupo de teatro con personas con diversidad funcional de la Asociación Síndrome de Down-Sevilla

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La investigación sobre el graffiti relacionado con el arte urbano, el diseño y la comunicación visual, la cultura social y política en la ciudad de Bogotá, son temas que concentran esta investigación. Opiniones y entrevistas fueron revelando la influencia sobre la comunidad, la sociedad civil, la política, y el enfrentamiento radical con la leyes, su clasificación y su exigencia según el estrato social han hecho de los espacios públicos de Bogotá una ciudad con paredes hablantes. Aunque no es tomado como algo malo, -para algunos- vandalismo para otros, despierta en muchos, opiniones diversas y sobre todo una subestimada valoración de los artistas hacia una expresión liberal y democrática de un sistema que los aleja de cualquier exhibición del arte tradicional.

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Starting from the famous and enigmatic quotation of the Aristotle’s Poetics, who argues that the human has a natural desire and pleasure to see corpses if mediated by art, is intended to show the relationship between the attraction for the horror and some contemporary art practices surrounding the depiction of death, particularly with regard to the ultimate use of the human corpse as an artistic resource. Avoiding any kind of ethical approach or questioning of the limits of the artistic production, is meant to highlight the phenomenon through the examples brought out by the work of some contemporary artists such as Andy Warhol, Eric Fischl, Damien Hirst, Von Hagens, Andres Serrano, Joel-Peter Witkin and Teresa Margolles: From those who use the corpse in and turn it in something aesthetically pleasant, to others who turn human corpses in sculptures of scientific value, and further other kind of artists who assume the morbid and dramatic life of the corpse in their art production as something structural.

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Generation of reactive oxygen species (ROS) is increasingly recognized as an important cellular process involved in numerous physiological and pathophysiological processes. Complex I ( NADH: ubiquinone oxidoreductase) is considered as one of the major sources of ROS within mitochondria. Yet, the exact site and mechanism of superoxide production by this large membrane-bound multiprotein complex has remained controversial. Here we show that isolated complex 1 from Yarrowia lipolytica forms superoxide at a rate of 0.15% of the rate measured for catalytic turnover. Superoxide production is not inhibited by ubiquinone analogous inhibitors. Because mutant complex I lacking a detectable iron-sulfur cluster N2 exhibited the same rate of ROS production, this terminal redox center could be excluded as a source of electrons. From the effect of different ubiquinone derivatives and pH on this side reaction of complex I we concluded that oxygen accepts electrons from FMNH2 or FMN semiquinone either directly or via more hydrophilic ubiquinone derivatives.

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High-resolution optical spectra of 57 Galactic B-type supergiant stars have been analysed to determine their rotational and macroturbulent velocities. In addition, their atmospheric parameters (effective temperature, surface gravity and microturbulent velocity) and surface nitrogen abundances have been estimated using a non-local thermodynamic equilibrium grid of model atmospheres. Comparisons of the projected rotational velocities have been made with the predictions of stellar evolutionary models and in general good agreement was found. However, for a small number of targets, their observed rotational velocities were significantly larger than predicted, although their nitrogen abundances were consistent with the rest of the sample. We conclude that binarity may have played a role in generating their large rotational velocities. No correlation was found between nitrogen abundances and the current projected rotational velocities. However, a correlation was found with the inferred projected rotational velocities of the main-sequence precursors of our supergiant sample. This correlation is again in agreement with the predictions of single star evolutionary models that incorporate rotational mixing. The origin of the macroturbulence and microturbulent velocity fields is discussed and our results support previous theoretical studies that link the former to subphotospheric convection and the latter to non-radial gravity mode oscillations. In addition, we have attempted to identify differential rotation in our most rapidly rotating targets.

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A new approach to the synthesis of dipeptides is described based on the formation of the CONH-CHRCO bond by carbenoid N-H insertion, rather than the formation of the peptide bond itself. The key N-H insertion reaction was carried out by treating a mixt. of N-protected amino acid amide and tri-Et diazophosphonoacetate, EtO2CC(:N2)PO(OEt)2, with a catalytic amt. of Rh2(OAc)4 in toluene to form phosphonates, e.g. I (R1 = H, Me, iso-Pr, iso-Bu; R2 = PhCH2O2C, Me3CO2C) in good yield. Dehydro dipeptides, e.g. II (R1, R2 = same as above; R3 = Ph, iso-Pr, N-Boc-indol-3-yl) were prepd. by Wadsworth-Emmons reaction of the phosphonates I with R3CHO using DBU as base.

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Rhodium(II) acetate-catalyzed reaction of Et 2-diazo-2-diethoxyphosphorylate, EtO2CC(:N2)PO(OEt)2, with carbamates, amides, ureas or anilines gives a range of N-substituted 2-amino-2-diethoxyphosphorylacetates, EtO2CCH(NHR1)PO(OEt)2 (where R1 = Boc, Cbz, acetyl, propionyl, pivaloyl, n-Pr, Ph and substituted Ph groups), by N-H insertion reaction of the intermediate rhodium carbenoid.

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Rh(II) acetate-catalyzed decompn. of diazophenylacetates PhC(N2)CO2Me 1 and PhC(N2)CO2R* 3 [R*OH = (-)-borneol, (+)-menthol, (-)-8-phenylmenthol] in the presence of a range of N-H compds. results in an N-H insertion reaction of the intermediate carbenoids and formation of N-substituted phenylglycine derivs. PhCH(NR1R2)CO2Me 2 [R1 = R2 = Et; R1 = 4-MeOC6H4, COCH2CHMe2, CO2CH2Ph, (S)-CH(CO2Me)CH2Ph, (S)-CHMePh, R2 = H; 64-83% yields] and PhCH(NR1R2)CO2R* 4 (R1 = R2 = Et; R1 = COMe, CO2Me, R2 = H; same R*; 37-71% yields). The corresponding reactions of di-Me ?-diazobenzylphosphonate PhC(N2)P(O)(OMe)2 5 with primary amines constitute a simple route to aminophosphonates PhCH(NHR)P(O)(OMe)2 6 (R = COMe, COEt, CO2CH2Ph, CO2CMe3, 4-ClC6H4, 4-MeC6H4, 4-MeOC6H4; 13-96% yields).

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Substituted phenols undergo a facile Rh carbenoid-mediated O-H insertion reaction with (EtO)2P(O)C(:N2)CO2R (I; R = Et, Me) to give 44-86% 2-aryloxyphosphonoacetates II (R1 = e.g., H, 4-Me, 4-Cl, 2-OH, 4-PhCH2O). Phenols contg. strongly electron withdrawing groups, bulky ortho-substituents or certain ortho-heteroatom substituents show reduced or variable yields. Catechol affords a mono-adduct which cyclizes to lactate III. Aniline inserts preferentially and exclusively over phenol in a competition reaction with I (R = Et) to give (EtO)2P(O)CH(NHPh)CO2Et. II are versatile intermediates in a prepn. of 2-aryloxy-3-phenylpropenoates IV by Wadsworth-Emmons reaction with benzaldehydes R2C6H4CHO (R2 = PhCH2O, 2-Cl, H). Dissolving Mg metal redn. provides a mild method for the conversion of propenoates IV into the corresponding propanoates.

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Rhodium(II) carboxylate catalyzed decompn. of diazo esters 3 (shown as I) and PhCH2C(CO2Et)N2 4 in the presence of alcs. or water results in formation of 2-alkoxy- or 2-hydroxy-3-arylpropanoates, resp., by O-H insertion in competition with cinnamates by elimination; the ratio of insertion to elimination is dramatically affected by the carboxylate ligand on rhodium. Use of methanol-d as the alc. confirms that the alkene does not arise by elimination from the initial alkoxyester product.

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This paper discusses the monitoring of complex nonlinear and time-varying processes. Kernel principal component analysis (KPCA) has gained significant attention as a monitoring tool for nonlinear systems in recent years but relies on a fixed model that cannot be employed for time-varying systems. The contribution of this article is the development of a numerically efficient and memory saving moving window KPCA (MWKPCA) monitoring approach. The proposed technique incorporates an up- and downdating procedure to adapt (i) the data mean and covariance matrix in the feature space and (ii) approximates the eigenvalues and eigenvectors of the Gram matrix. The article shows that the proposed MWKPCA algorithm has a computation complexity of O(N2), whilst batch techniques, e.g. the Lanczos method, are of O(N3). Including the adaptation of the number of retained components and an l-step ahead application of the MWKPCA monitoring model, the paper finally demonstrates the utility of the proposed technique using a simulated nonlinear time-varying system and recorded data from an industrial distillation column.

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The central theme of this investigation is to evaluate the feasibility of using bituminous coal as a precursor material for the production of chars and activated carbons using physical and chemical activation processes. The chemical activation process was accomplished by impregnating the raw materials with different dehydrating agents in different ratios and concentrations, prior to heat treatment (ZnCl2, KCl, KOH, NaOH and Fe2(SO4)3·xH2O). Steam activation of the precursor material was adopted for the preparation of activated carbon using physical activation technology. Different types of bituminous coal; namely, contaminated Columbian (contaminated with pet. coke), pure Columbian, Venezuelan and New Zealand bituminous coal were used in the production processes. BET surface area, micropore area, pore size distribution and total pore volume of the chars and activated carbons were determined from N2 adsorption/desorption isotherm, measured at 77 K. Charring conditions, charring temperature of 800 °C and charring time of 4 h, proved to be the optimum conditions for preparing chars. Contaminated Columbian were found to be the best precursor material for the production of char with reasonable physical characteristics (surface area = 138.1 m2 g-1 and total pore volume of 8.656 × 10-0.2 cm3 g-1). An improvement in the physical characteristics of the activated carbons was obtained upon the treatment of coal with dehydrating agents. Contaminated Columbian treated with 10 wt% ZnCl2 displayed the highest surface area and total pore volume (surface area = 231.5 m2 g-1 and total pore volume = 0.1227 cm3 g-1) with well-developed microporisity (micropore area = 92.3 m2 g-1). Venezuelan bituminous coal using the steam activation process was successful in producing activated carbon with superior physical characteristics (surface area = 863.50 m2 g-1, total pore volume = 0.469 cm3 g-1 and micropore surface area = 783.58 m2 g-1).

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Porous carbon aerogels are prepared by polycondensation of resorcinol (R) and formaldehyde (F)catalyzed by sodium carbonate (C) followed by carbonization of the resultant aerogels at 800? in an inert atmosphere. The porous texture of the carbons has been adjusted by the change of the molar ratio of resorcinol to catalyst (R/C) in the gel precursors in the range of 100 to 500. The porous structure of the aerogels and carbon aerogels are characterized by N2 adsorption-desorption measurements at 77 K. It is found that total pore volume and average pore diameter of the carbons increase with increase in the R/C ratio of the gel precursors.The prepared carbon aerogels are used as active materials in fabrication of composite carbon electrodes. The electrochemical performance of the electrodes has been tested by using them as cathodes in a Li/O2 cell. Through the galvanostatic charge/discharge measurements, it is found that with an increase of R/C ratio, the specific capacity of the Li/O2 cell fabricated from the carbon aerogels increases from 716 to 2077 charge/discharge cycles indicate that the carbon samples possess excellent stability on cycling.