Influence of temperature on the interaction between Pd clusters and the TiO2 (110) surface

The behavior of a Pd nanocluster on the rutile TiO2 (110) surface has been analyzed by extensive first principles molecular dynamics simulations between 100 K and 1073 K. Calculations predict a steep change in the morphological and electronic cluster structure around 800 K in excellent agreement with previous experimental evidence. At low temperature, the cluster geometry is mainly controlled by the substrate structure; however, upon the transition temperature, the cluster-substrate interaction decreases appreciably, and the cluster adopts a geometry more stable in vacuum and becomes metallic. These results illustrate at an atomistic level the influence of temperature on the geometrical and electronic properties of oxide-supported clusters.Ministerio de Educación y Ciencia MAT2005-0187

Oxygen vacancies on TiO2 (110) from first principles calculations

We have carried out a systematic study of oxygen vacancy formation on the TiO2 ~110! surface by means of plane-wave pseudopotential density-functional theory calculations. We have used models with the mean number of vacancies per surface unit cell being u50.25 and u50.5. The study comprises several kind of vacancies within the outermost layers of the surface. The use of a suitable set of technical parameter is often essential in order to get accurate results. We find that the presence of bridging vacancies is energetically favored in accordance to experimental data, although the formation of sub-bridging vacancies might be possible at moderate temperatures. Surprisingly, the spin state of the vacancy has little influence on the results. Atomic displacements are also analyzed and found to be strongly dependent on the particular arrangement of vacancies.Dirección General de Enseñanza Superior e Investigación Científica. España (DGESIC) MAT2002-57

Molecular-dynamics simulations of liquid aluminum oxide

The total and partial radial distribution functions g(r) and the corresponding structure factors S(q) were calculated based on molecular-dynamics simulations in the microcanonical ensemble of liquid aluminum oxide. The simulations were performed in the temperature range 2300-3000 K in order to explore the temperature dependence of the structure, finding that the liquid structure is invariant as a function of temperature. With the aid of the partial radial distribution functions, it is possible to reinterpret the experimental data leading to a new assignment of peaks which differs from the one reported in a previously published work by Ansell et al. [Phys. Rev. Lett. 78, 464 (1997)]. The structural model for liquid aluminum oxide obtained from our simulations is essentially the same as that reported in the experimental work.Dirección General de Investigaciones Científicas y Técnicas PB95-124

Molecular modification of coumarin dyes for more efficient dye sensitized solar cells

solo para uso personalIn this work, new coumarin based dyes for dye sensitized solar cells (DSSC) have been designed by introducing several substituent groups in different positions of the NKX-2311 structure. Two types of substitutions have been considered: the introduction of three electron-donating groups (–OH, –NH2, and –OCH3) and two different substituents with steric effect: –CH2–CH2–CH2– and –CH2–HC=CH–. The electronic absorption spectra (position and width of the first band and absorption threshold) and the position of the LUMO level related to the conduction band have been used as theoretical criteria to evaluate the efficiency of the new dyes. The introduction of a –NH2 group produces a redshift of the absorption maximum position and the absorption threshold, which could improve the cell efficiency. In contrast, the introduction of –CH2–CH2–CH2– does not modify significantly the electronic structure of NKX-2311, but it might prevent aggregation. Finally, –CH2– HC=CH– produces important changes both in the electronic spectrum and in the electronic structure of the dye, and it would be expected as an improvement of cell efficiency for these dyes.Ministerio de Ciencia e Innovación de España-MAT2008-4918 y CSD2008-002

Molecular-dynamics simulations of premelting processes in Cr2O3

Molecular-dynamics simulations of the (0001) surface Of Cr2O3 were carried out in the [300-2800 K] range of temperatures using a classical Pauling-type pair potential. The analysis of the structural data shows a strong surface relaxation in agreement with experiment. Both static and dynamic surface properties indicate that a surface melting process occurs well below the melting point, which is estimated to be about 2500 K, in excellent agreement with the experimental value of 2556 K. The diffusive properties of this disordered phase are described and it is found that the main mechanism for diffusion involves hopping of surface atoms.Comisión Interministerial de Ciencia y Tecnología MAT97- 0717 y PB95-124

Runoff Pollution Treatment Using An Up-Flow Equipment With Limestone And Geotextil filtration media

Runoff drags pollutant from different urban surfaces causing diffuse pollution in natural or artificial water bodies. To solve this problem, several solutions have been developed to purify the run-off water before the final spill, but still it is necessary to improve the applicability and efficiency of these systems. The project that is presented in this paper is focused on developing a System for Catchment, Pre-treatment and Treatment (SCPT) of contaminated runoff coming from impervious surfaces. The concept of SCPT is an on-line, up-flow filtration system, with the main elements of pervious pavements, which are being geotextiles and open grade gravel. The objectives of this research are to determine the influence of the main factors that affect SCPT efficiency and to evaluate the effects of SCPT long term use in its operational behavior

Cardiac Defense Reactivity and Cognitive Flexibility in High- and Low-Resilience Women

The present study analyzes, in a sample of 54 young women, the relationships between high or low resilience, measured with the Connor- Davidson Resilience Scale questionnaire and the Spanish adaptation of the Resilience Scale, and two indices of psychophysiological and neuropsychological adaptability, the cardiac defense response (CDR) and cognitive flexibility. The results showed that the more resilient people, in addition to having better scores on mental health questionnaires, obtained better scores in cognitive flexibility than the less resilient people. Regarding the CDR, both groups showed the typical response pattern to unexpected intense noise, with two successive accelerationdeceleration components. However, the more resilient people had a larger initial acceleration-deceleration, which is indicative of greater vagal control, than the less resilient people. No significant differences were found in the second acceleration-deceleration, which is indicative of sympathetic control. The present findings broaden the understanding of how resilient people change their adaptable responses to address environmental demands.Project PSI2014-56924-P, funded by the Ministry of Economy and Competitivenes

Customized FBG based photonic superstructure for UWB signal generation applications

This paper proposes and experimentally demonstrates a compact and scalable approach for high-order UWB pulses based on phase-to-intensity conversion by means of a FBG photonic superstructure. In this scheme, we have designed a customized FBG assemblage that permits lineal combination of UWB low-order derivatives to generate high order pulse generation. Experimental results are depicted from the preliminary design of the array. The generated pulses are presented in both time and frequency domain, revealing a proper fit in terms of the FCC settled mask and hence, optimal efficiency percentages

The MAL protein is crucial for proper membrane condensation at the ciliary base, which is required for primary cilium elongation

The base of the primary cilium contains a zone of condensedmembranes whose importance is not known. Here, we have studiedthe involvement of MAL, a tetraspanning protein that exclusivelypartitions into condensed membrane fractions, in the condensation ofmembranes at the ciliary base and investigated the importance ofthese membranes in primary cilium formation. We show that MALaccumulates at the ciliary base of epithelial MDCK cells. Knockdownof MAL expression resulted in a drastic reduction in the condensationof membranes at the ciliary base, the percentage of ciliated cells andthe length of the cilia, but did not affect the docking of the centrosometo the plasma membrane or produce missorting of proteins to thepericentriolar zone or to the membrane of the remaining cilia. Rab8(for which there are two isoforms, Rab8A and Rab8b), IFT88 andIFT20, which are important components of the machinery of ciliarygrowth, were recruited normally to the ciliary base of MAL-knockdowncells but were unable to elongate the primary cilium correctly. MAL,therefore, is crucial for the proper condensation of membranes at theciliary base, which is required for efficient primary cilium extension

Out-Of-Pocket Expenditures on Dental Care for Schoolchildren Aged 6 to 12 Years: A Cross-Sectional Estimate in a Less-Developed Country Setting

Aim: The objective of this study was to estimate the Out-Of-Pocket Expenditures (OOPEs) incurred by households on dental care, as well as to analyze the sociodemographic, economic, and oral health factors associated with such expenditures. Method: A cross-sectional study was conducted among 763 schoolchildren in Mexico. A questionnaire was distributed to parents to determine the variables related to OOPEs on dental care. The amounts were updated in 2017 in Mexican pesos and later converted to 2017 international dollars (purchasing power parities-PPP US $). Multivariate models were created: a linear regression model (which modeled the amount of OOPEs), and a logistic regression model (which modeled the likelihood of incurring OOPEs). Results: The OOPEs on dental care for the 763 schoolchildren were PPP US$53,578, averaging a PPP of US $70.2 ± 123.7 per child. Disbursements for treatment were the principal item within the OOPEs. The factors associated with OOPEs were the child's age, number of dental visits, previous dental pain, main reason for dental visit, educational level of mother, type of health insurance, household car ownership, and socioeconomic position. Conclusions: The average cost of dental care was PPP US$70.2 ± 123.7. Our study shows that households with higher school-aged children exhibiting the highest report of dental morbidity-as well as those without insurance-face the highest OOPEs. An array of variables were associated with higher expenditures. In general, higher-income households spent more on dental care. However, the present study did not estimate unmet needs across the socioeconomic gradient, and thus, future research is needed to fully ascertain disease burden