Second-harmonic generation of ZnO nanoparticles synthesized by laser ablation of solids in liquids

We report the synthesis of small zinc oxide nanoparticles (ZnO NPs) based colloidal suspensions and the study of second-harmonic generation from aggregated ZnO NPs deposited on glass substrates. The colloidal suspensions were obtained using the laser ablation of solids in liquids technique, ablating a Zn solid target immersed in acetone as the liquid medium, with ns-laser pulses (1064 nm) of a Nd-YAG laser. The per pulse laser fluence, the laser repetition rate frequency and the ablation time were kept constant. The absorption evolution of the obtained suspensions was optically characterized through absorption spectroscopy until stabilization. Raman spectroscopy, SEM and HRTEM were used to provide evidence of the ZnO NPs structure. HRTEM results showed that 5–8 nm spheroids ZnO NPs were obtained. Strong second-harmonic signal is obtained from random ZnO monocrystalline NPs and from aggregated ZnO NPs, suggesting that the high efficiency of the nonlinear process may not depend on the NPs size or aggregation state

Vivianite (ferrous phosphate) alleviates iron chlorosis in grapevine

Synthetic vivianite [Fe3(PO4)2·8H2O] has been reported to alleviate iron (Fe) chlorosis in crops growing on calcareous soils. To test the effectiveness of vivianite in grapevine we carried out three-year (2003 to 2005) experiments in vineyards located in six different areas of Spain with Denomination of Origin (Rioja, Ribera del Duero, La Mancha, Montilla-Moriles, Condado de Huelva, and Jerez), which differed in grapevine rootstock/variety, climate, and soil properties. In all cases there was at least one treatment in which a suspension of vivianite was injected into the soil at the beginning of the experiment in spring, one control (“–Fe”, no Fe fertilizer added) treatment, and one or more treatments with Fe chelate (FeEDDHA) or an Fe(II) salt applied yearly. The concentration of chlorophyll per unit leaf area was estimated with a portable chlorophyll meter (readings in SPAD units). The SPAD value and the trunk perimeter increment of the vines fertilized with vivianite were significantly higher than those of the control (-Fe) vines through the three years in all fields except the Jerez one. Vivianite was not significantly more effective than Fe-sulfate (in Rioja field) or Fe chelate (in La Mancha field). Our results suggest in summary that vivianite is effective in improving the Fe nutrition of vine and has a significant long-lasting effect of at least three years. This is ascribed to vivianite being incongruently dissolved to produce a poorly crystalline Fe oxide phase (lepidocrocite), which is considered to be a good source of Fe to plant. Vivianite is effective, readily prepared in the field, not easily leached from the soil, cheap, and environmentally safe, constituting thus an adequate Fe fertilizer for grapevine.

Plagiarism meets paraphrasing: insights for the new generation in automatic plagiarism detection

Although paraphrasing is the linguistic mechanism underlying many plagiarism cases, little attention has been paid to its analysis in the framework of automatic plagiarism detection. Therefore, state-of-the-art plagiarism detectors find it difficult to detect cases of paraphrase plagiarism. In this article, we analyse the relationship between paraphrasing and plagiarism, paying special attention to which paraphrase phenomena underlie acts of plagiarism and which of them are detected by plagiarism detection systems. With this aim in mind, we created the P4P corpus, a new resource which uses a paraphrase typology to annotate a subset of the PAN-PC-10 corpus for automatic plagiarism detection. The results of the Second International Competition on Plagiarism Detection were analysed in the light of this annotation. The presented experiments show that (i) more complex paraphrase phenomena and a high density of paraphrase mechanisms make plagiarism detection more difficult, (ii) lexical substitutions are the paraphrase mechanisms used the most when plagiarising, and (iii) paraphrase mechanisms tend to shorten the plagiarized text. For the first time, the paraphrase mechanisms behind plagiarism have been analysed, providing critical insights for the improvement of automatic plagiarism detection systems

Multiple Independent Retroelement Insertions in the Promoter of a Stress Response Gene Have Variable Molecular and Functional Effects in Drosophila

[Abstract] Promoters are structurally and functionally diverse gene regulatory regions. The presence or absence of sequence motifs and the spacing between the motifs defines the properties of promoters. Recent alternative promoter usage analyses in Drosophila melanogaster revealed that transposable elements significantly contribute to promote diversity. In this work, we analyzed in detail one of the transposable element insertions, named FBti0019985, that has been co-opted to drive expression of CG18446, a candidate stress response gene. We analyzed strains from different natural populations and we found that besides FBti0019985, there are another eight independent transposable elements inserted in the proximal promoter region of CG18446. All nine insertions are solo-LTRs that belong to the roo family. We analyzed the sequence of the nine roo insertions and we investigated whether the different insertions were functionally equivalent by performing 5’-RACE, gene expression, and cold-stress survival experiments. We found that different insertions have different molecular and functional consequences. The exact position where the transposable elements are inserted matters, as they all showed highly conserved sequences but only two of the analyzed insertions provided alternative transcription start sites, and only the FBti0019985 insertion consistently affects CG18446 expression. The phenotypic consequences of the different insertions also vary: only FBti0019985 was associated with cold-stress tolerance. Interestingly, the only previous report of transposable elements inserting repeatedly and independently in a promoter region in D. melanogaster, were also located upstream of a stress response gene. Our results suggest that functional validation of individual structural variants is needed to resolve the complexity of insertion clusters.[Author Summary] The presence of several transposable element insertions in the promoter region of a Drosophila melanogaster gene has only been described in heat shock protein genes. In this work, we have discovered and characterized in detail several naturally occurring independent transposable element insertions in the promoter region of a cold-stress response gene in the fruitfly Drosophila melanogaster. The nine transposable element insertions described are clustered in a small 368 bp region and all belong to the same family of transposable elements: the roo family. Each individual insertion is present at relatively low population frequencies, ranging from 1% to 17%. However, the majority of strains analyzed contain one of these nine roo insertions suggesting that this region might be evolving under positive selection. Although the sequence of these insertions is highly similar, their molecular and functional consequences are different. Only one of them, FBti0019985, is associated with increased viability in nonstress and in cold-stress conditions.This work was supported by the Ministerio de Economía y Competitividad (MINECO: http://www.idi.mineco.gob.es) BFU-2011-24397 and RYC-2010-07306 to JG, and BES-2012-052999 to AU, Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional (MINECO/FEDER:http://www.idi.mineco.gob.es) BFU2014-57779-P, the European Commission (https://ec.europa.eu) FP7-PEOPLE-2011-CIG-293860, the Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya (http://agaur.gencat.cat) 2014-SGR-201 to JG, and by the Agence Nationale de la Recherche (http://www.agence-nationale-recherche.fr) ANR-14-CE02-0003 to MARdC.USD 2250 APC fee funded by the EC FP7 Post-Grant Open Access PilotPeer reviewe

Influence of solar activity on hydrological processes

International audienceThe relationship between solar activity and the water volumes of lakes is searched here by means of correlational and spectral analysis methods. The level of two lakes, Pátzcuaro in México and Tchudskoye in Russia, together with solar activity indexes are used for the analysis. It is found that the source of the oscillation mechanism of the level of those lakes is the solar activity cycle through its influence on the magnetosphere and the terrestrial atmosphere. The present study allows for the development of long-period prognostic of water volumes of big lakes

Procedimiento de obtención de un material cerámico de forsterita

Procedimiento de obtención de un material cerámico de forsterita. Procedimiento de obtención de un material cerámico a partir de un silicato laminar hidroxilado, preferiblemente talco, que comprende: mezclar una suspensión acuosa de silicato laminar hidroxilado con óxido de magnesio; secar la suspensión obtenida anteriormente a una temperatura de hasta 350ºC; y tratar térmicamente el producto secado a una temperatura de hasta 1600ºC. Además, la invención se refiere a un material cerámico obtenible por el procedimiento descrito que comprende forsterita en una proporción de entre un 70% y un 95% en peso del material cerámico, y a sus aplicaciones como material refractario o como material electrocerámico.Peer reviewedConsejo Superior de Investigaciones ientifícas (España), Universidad de Sevilla, Universidad de AlmeríaA1 Solicitud de patente con informe sobre el estado de la técnic

Unbiased Global Optimization of Lennard-Jones Clusters for N <= 201 by Conformational Space Annealing Method

We apply the conformational space annealing (CSA) method to the Lennard-Jones clusters and find all known lowest energy configurations up to 201 atoms, without using extra information of the problem such as the structures of the known global energy minima. In addition, the robustness of the algorithm with respect to the randomness of initial conditions of the problem is demonstrated by ten successful independent runs up to 183 atoms. Our results indicate that the CSA method is a general and yet efficient global optimization algorithm applicable to many systems.Comment: revtex, 4 pages, 2 figures. Physical Review Letters, in pres

New Tetrahedral Global Minimum for the 98-atom Lennard-Jones Cluster

A new atomic cluster structure corresponding to the global minimum of the 98-atom Lennard-Jones cluster has been found using a variant of the basin-hopping global optimization algorithm. The new structure has an unusual tetrahedral symmetry with an energy of -543.665361, which is 0.022404 lower than the previous putative global minimum. The new LJ_98 structure is of particular interest because its tetrahedral symmetry establishes it as one of only three types of exceptions to the general pattern of icosahedral structural motifs for optimal LJ microclusters. Similar to the other exceptions the global minimum is difficult to find because it is at the bottom of a narrow funnel which only becomes thermodynamically most stable at low temperature.Comment: 3 pages, 2 figures, revte