Carbon dioxide emissions of Antarctic tourism

The increase of tourism to the Antarctic continent may entail not only local but also global environmental impacts. These latter impacts, which are mainly caused by transport, have been generally ignored. As a result, there is a lack of data on the global impacts of Antarctic tourism in terms of energy consumption and carbon dioxide emissions. This paper presents and applies a methodology for quantifying CO2 emissions, both for the Antarctic vessel fleet as a whole and per passenger (both per trip and per day). The results indicate that the average tourist trip to Antarctica results in 5.44 t of CO2 emissions per passenger, or 0.49 t per passenger and day. Approximately 70% of these emissions are attributable to cruising and 30% to flying, which highlights the global environmental relevance of local transport for this type of touris

Ionic conductivity of nanocrystalline yttria-stabilized zirconia: Grain boundary and size effects

9 páginas, 6 figuras, 3 tablas.-- PACS number(s): 66.30.H-.-- et al.We report on the effect of grain size on the ionic conductivity of yttria-stabilized zirconia samples synthesized by ball milling. Complex impedance measurements, as a function of temperature and frequency are performed on 10 mol % yttria-stabilized zirconia nanocrystalline samples with grain sizes ranging from 900 to 17 nm. Bulk ionic conductivity decreases dramatically for grain sizes below 100 nm, although its activation energy is essentially independent of grain size. The results are interpreted in terms of a space-charge layer resulting from segregation of mobile oxygen vacancies to the grain-boundary core. The thickness of this space-charge layer formed at the grain boundaries is on the order of 1 nm for large micron-sized grains but extends up to 7 nm when decreasing the grain size down to 17 nm. This gives rise to oxygen vacancies depletion over a large volume fraction of the grain and consequently to a significant decrease in oxide-ion conductivity.We acknowledge financial support by Junta de Comunidades de Castilla-La Mancha through Project No. PAI-05-013, by CAM under Grant No. S2009/MAT-1756 (Phama), by Spanish MICINN through Grants No. MAT2008-06517-C02, No. MAT2008-06542-C04, and No. FIS2009-12964- C05-04, and Consolider Ingenio 2010 under Grant No. CSD2009-00013 (Imagine).Peer reviewe

Simulation of gauge transformations on systems of ultracold atoms

We show that gauge transformations can be simulated on systems of ultracold atoms. We discuss observables that are invariant under these gauge transformations and compute them using a tensor network ansatz that escapes the phase problem. We determine that the Mott-insulator-to-superfluid critical point is monotonically shifted as the induced magnetic flux increases. This result is stable against the inclusion of a small amount of entanglement in the variational ansatz.Comment: 14 pages, 6 figure

X-ray magnetic circular dichroism measurements using an X-ray phase retarder on the BM25 A-SpLine beamline at the ESRF

6 páginas, 8 figuras.Circularly polarized X-rays produced by a diamond X-ray phase retarder of thickness 0.5 mm in the Laue transmission configuration have been used for recording X-ray magnetic circular dichroism (XMCD) on the bending-magnet beamline BM25A (SpLine) at the ESRF. Field reversal and helicity reversal techniques have been used to carry out the measurements. The performance of the experimental set-up has been demonstrated by recording XMCD in the energy range from 7 to 11 keV.This work was partially supported by a Spanish CICYTMAT2008- 06542-C04 grant. MALM and RB acknowledge the Ministerio de Ciencia e Innovación of Spain for their Postdoctoral and PhD grants, respectively. We also acknowledge the Spanish Ministerio de Ciencia e Innovación and Consejo Superior de Investigaciones Científicas for financial support.Peer reviewe

The hydration structure of Cu2+: More tetrahedral than octahedral?

A comprehensive multi-technique approach has been used to address the controversial question of the preferred geometric form of the Cu2+ aqua-ion hydration shell. A combination of H/D isotopic substitution neutron scattering and X-ray scattering has been used to refine atomistic models of 0.5 m and 2.0 m solutions of Cu(ClO4)2, that have also been constrained to simultaneously reproduce detailed local structure information about the cation environment obtained by X-ray Absorption spectroscopy. The adoption of the Empirical Potential Structure Refinement (EPSR) technique as a single unified analytical framework minimises the chances for biasing the result in favour of a specific pre-conceived outcome. The results are consistent with an average coordination for each Cu2+ ion of 4.5 ± 0.6 water molecules that matches the more recent picture of five-fold coordination in a 2.0 m solution, but interestingly this combined study highlights that the preferred local geometry of the ion sites is found to have a mixed character of tetrahedral, trigonal bipyramidal and octahedral components. A further point to note is that this new model adds support to a largely ignored result in the literature relating to the linear electric field effect induced g-shifts observed in the electron paramagnetic resonance spectra of glassy Cu2+ complexes (Peisach and Mims, Chem. Phys. Lett., 1976, 37, 307–310) that first highlighted the importance of tetrahedral distortions in the cation's hydration shell structure

Método estadístico para modelar la creciente de la cuenca del río coello

Se presenta en este artículo un ejemplo de la metodológíco paro modelar crecientes o partir del análisis de la información de caudales máximos, realizando de los recolectados en una de las estaciones (Puente Carretera) de la cuenca Hidrográfica del Río Coello, El método utilizado consiste en estimar los parámetros para cada una de las siguientes distribuciones de probabilidad: Distribución de valores extremos, log-normal, log-Pearson tipo III y distribución de Wakeby; posteriormente calcular el periodo de retorno (Tr =l/f(x),) y hacer un análisis gráfico para Indicar cual modelo tiene el mejor ajuste y así modelar la creciente para predecir en frecuencia y magnitud los eventos extremos que puedan ocurrir en el futuro

Trace cisplatin and carboplatin removal by 3-mercaptopropionic acid and L-cysteine functionalized sponges : Adsorption behaviour and mechanism

Altres ajuts: acords transformatius de la UABThis study presents functionalized open-celled cellulose Metalzorb® sponge (Sponge) with 3-mercaptopropionic acid (MPA) and L-Cysteine (Cys), and the resulting MPA@Sponge and Cys@Sponge showed significantly improved removal efficiency towards trace cisplatin and carboplatin against Sponge. MPA@Sponge achieved maximum removal of 88.9 ± 0.5% for cisplatin and 85.2 ± 0.4% for carboplatin, while Cys@Sponge achieved maximum removal of 75 ± 2% and 59 ± 1%. In contrast, Sponge only achieved removal of 29 ± 4% and 4 ± 1%, respectively. It suggests that thiol groups serve as favourable binding sites for Pt complexation. Carboplatin exhibits lower adsorption compared to cisplatin due to its limited hydration. However, the presence of Cl in stock and high temperature facilitate the hydration and the formation of active derivatives of carboplatin, thereby enhancing its adsorption. The rapid adsorption processes of cisplatin and carboplatin are well described by the pseudo-second-order kinetic model involving diffusion and chemisorption. The results from adsorption isotherms revealed a monolayer adsorption that aligns with the principles proposed by the Langmuir model. High temperature significantly enhances the adsorption, and the positive enthalpies indicate that the binding of Pt with thiol groups is endothermic process. X-ray absorption spectroscopy measurements at the Pt L-edge revealed a similar coordination environment of the adsorbed Pt on both functionalized adsorbents, which can be attributed to the formation of four Pt-S bonds during the adsorption. To assess the validity of the adsorption results under realistic medium conditions, an adsorption study was carried out by using diluted urine spiked with trace platinum cytostatic drugs to simulate hospital wastewater. 90.2 ± 0.3% of cisplatin and 77.0 ± 0.2% of carboplatin was effectively removed by MPA@Sponge from diluted urine