12 resultados para 343.08

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


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This note develops a behavioral framework to classify individual contingent valuation (CV) respondents in terms of the warm glow and altruistic motives in their WTP responses. We suggest that at least five possible behavioral categories for CV responses may exist, depending on the type of underlying preferences and whether respondents are satiated or non-satiated with respect to the good. An empirical example suggests that the warm glow motive may be present in the majority of bids, although its presence does not necessarily preclude scope sensitivity to the quantity/quality of an environmental good. (C) 2000 Elsevier Science B.V. All rights reserved.

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Vertically aligned ZnO nanowires (NWs) with a length of 1.5-10 mu m and a mean diameter of ca. 150 nm were grown by chemical vapour deposition onto a c-oriented ZnO seed layer which was deposited by atomic layer deposition on Si substrates. The substrates were then spin-coated with an ethanol solution containing Pd nanoparticles with an average size of 2.7 and 4.5 nm. A homogeneous distribution of the Pd nanoparticles on ZnO NWs has been obtained using both Pd particle series. The catalytic activity of the ZnO NWs and Pd/ZnO NWs catalysts was measured in the semihydrogenation of 2-methyl-3-butyn-2-ol at 303-343 K and a pressure of 2-10 bar. The effect of the solvent used on the catalytic performance of the Pd/ZnO NWs catalyst was studied. The Pd/ZnO catalysts showed alkene selectivity of up to 95% at an alkyne conversion of 99%. A kinetic model is proposed to explain the activity and selectivity of the ZnO support and Pd/ZnO catalysts.

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The supernova SN 2001du was discovered in the galaxy NGC 1365 at a distance of 19 +/- 2 Mpc, and is a core-collapse event of Type II-P. Images of this galaxy, of moderate depth, have been taken with the Hubble Space Telescope approximately 6.6 yr before discovery and include the supernova position on the WFPC2 field of view. We have observed the supernova with the WFPC2 to allow accurate differential astrometry of SN 2001du on the pre-explosion frames. As a core-collapse event it is expected that the progenitor was a massive, luminous star. There is a marginal detection (3sigma) of a source close to the supernova position on the pre-discovery V -band frame, but it is not precisely coincident and we do not believe it to be a robust detection of a point source. We conclude that there is no stellar progenitor at the supernova position and derive sensitivity limits of the pre-discovery images that provide an upper mass limit for the progenitor star. We estimate that the progenitor had a mass of less than 15 M-circle dot . We revisit two other nearby Type II-P supernovae that have high-quality pre-explosion images, and refine the upper mass limits for the progenitor stars. Using a new distance determination for SN 1999gi from the expanding photosphere method, we revise the upper mass limit to 12 M-circle dot . We present new HST images of the site of SN 1999em, which validate the use of lower spatial resolution ground-based images in the progenitor studies and use a new Cepheid distance to the galaxy to measure an upper mass limit of 15 M-circle dot for that progenitor. Finally we compile all the direct information available for the progenitors of eight nearby core-collapse supernovae and compare their mass estimates. These are compared with the latest stellar evolutionary models of pre-supernova evolution which have attempted to relate metallicity and mass to the supernovae type. Although this is statistically limited at present, reasonable agreement is already found for the lower-mass events (generally the II-P), but some discrepancies appear at higher masses.

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Experimental values for the solubility of carbon dioxide, ethane, methane, oxygen, nitrogen, hydrogen, argon and carbon monoxide in 1-butyl-3- methylimidazolium tetrafluoroborate, [bmim][BF4] - a room temperature ionic liquid - are reported as a function of temperature between 283 K and 343 K and at pressures close to atmospheric. Carbon dioxide is the most soluble gas with mole fraction solubilities of the order of 10-2. Ethane and methane are one order of magnitude more soluble than the other five gases that have mole fraction solubilities of the order of 10-4. Hydrogen is the less soluble of the gaseous solutes studied. From the variation of solubility, expressed as Henry's law constants, with temperature, the partial molar thermodynamic functions of solvation such as the standard Gibbs energy, the enthalpy, and the entropy are calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry's law constants from appropriate smoothing equations is of 1%. © 2005 Elsevier Ltd. All rights reserved.

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Experimental values for the solubility of carbon dioxide and hydrogen in three room temperature ionic liquids based on the same anion- (bistrifluoromethylsulfonyl)imide [Ntf2]-and three different cations-1-butyl-3-methylimidazolium, [C4mim], 1-ethyl-3- methylimidazolium, [C2mim] and trimethyl-butylammonium, [N 4111]-are reported between 283 and 343 K and close to atmospheric pressure. Carbon dioxide, with a mole-fraction solubility of the order of 10-2, is two orders of magnitude more soluble than hydrogen. The solubility of CO2 is very similar in the three ionic liquids although slightly lower in the presence of the [C2mim] cation. In the case of H2, noticeable differences were observed with larger mole fraction solubilities in the presence of [N4111] followed by [C 4mim]. All of the mole-fraction solubilities decrease with increasing temperature. From the variation of Henry's law constants with temperature, the thermodynamic functions of solvation were calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry's law constants from appropriate smoothing equations, is always better than ±1%. © Springer Science+Business Media, LLC 2007.

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Objective: To compare maternal and fetal leptin among women without diabetes, women with type 1 diabetes, and women with type 2 diabetes. 

Methods: In a prospective study at the National Maternity Hospital, Dublin, 40 women with type 1 diabetes, 10 with type 2 diabetes, and 30 without diabetes were enrolled between July 2006 and July 2008. Maternal (36-week) and cord blood leptin was measured by enzyme-linked immunoassay. 

Results: No difference was found in maternal leptin among the groups: without diabetes (mean, range): 325 pg/mL, 36-1492 pg/mL; type 1 diabetes: 343.2 pg/mL, 55.5-1108.2 pg/mL; type 2 diabetes: 2022 pg/mL, 35.1-1553.3 pg/mL (P>0.05). Leptin levels were higher among fetuses of women with type 1 (223 pg/mL, 25.7-810 pg/mL) and type 2 (447.2 pg/mL, 1363-679 pg/mL) diabetes than among women without diabetes (803 pg/mL, 273-623.1 pg/mL; P<0.05). The single significant predictor of fetal leptin for the whole cohort was maternal body mass index (BMI; r=039, P=0.01). Only third-trimester glycosylated hemoglobin (HbA1c) was significantly related to fetal leptin after controlling for maternal BMI among women with diabetes (r=028, P=0.04).

 Conclusion: Fetuses of women with diabetes might have some degree of leptin resistance. This might be important in appetite regulation in extrauterine life. (C) 2012 International Federation of Gynecology and Obstetrics.