Search results for "CLUSTER"
showing 10 items of 3640 documents
El distrito industrial cerámico de la Plana de Castellón (España): Enraizamiento local y proyección global en un contexto de crisis
2016
En el presente artículo, realizamos un análisis de la evolución reciente del cluster cerámico de Castellón, un distrito industrial “canónico” que se ha caracterizado históricamente por su capacidad de adaptación y potencial innovador, y que ha experimentado un fuerte impacto de la crisis económica que se inicia en España en 2008. Este impacto se ha traducido tanto en el cierre de empresas como en un importante aumento del paro registrado, superior al experimentado por el conjunto de la región valenciana. Sin embargo, las empresas del distrito, o al menos una parte significativa de ellas, han desarrollado una serie de estrategias, en su mayor parte de carácter ofensivo, que han permitido una…
Alternative Military Keynesianism as a Tool of Civil-Military Cooperation in the Framework of the EU Defence Policy
2015
During the last year the security threats to the European Union have increased dramatically under the influence of military crisis in eastern Ukraine and Islamic terrorist activities in Europe. Consequently the demand for defence in the member states of the European Union has become greater than in previous years.This situation leads to the dilemma when the high level of defence expenditure can hamper the financial support of other sectors of national economy.Therefore it is necessary to increase the efficiency of available financial resources that have been allocated for the defence without a significant increase in defence expenditure. In order to achieve this efficiency the concept of cl…
Surfactant-assisted synthesis of Cd1−xCoxS nanocluster alloys and their structural, optical and magnetic properties
2010
We report the synthesis of Co-doped CdS nanoclusters (Cd1−xCoxS) for different doping concentrations (x = 0.10, 0.20 and 0.30) and characterization of their structural, optical, and magnetic properties. The structural properties studied by X-ray diffraction revealed hexagonal-greenockite structure and a decrease of the lattice parameters (a and c) with doping, showing incorporation of Co in the lattice. The morphology of the nanoclusters was studied by scanning electron microscopy. The optical absorption studies, using diffused reflectance spectroscopy, revealed that Co doping modifies the absorption band edge. Ferromagnetic phase was observed in the magnetization measurements at room-tempe…
Optical determination and identification of organic shells around nanoparticles: application to silver nanoparticles
2013
We present a simple method to prove the presence of an organic shell around silver nanoparticles. This method is based on the comparison between optical extinction measurements of isolated nanoparticles and Mie calculations predicting the expected wavelength of the Localized Surface Plasmon Resonance of the nanoparticles with and without the presence of an organic layer. This method was applied to silver nanoparticles which seemed to be well protected from oxidation. Further experimental characterization via Surface Enhanced Raman Spectroscopy (SERS) measurements allowed to identify this protective shell as ethylene glycol. Combining LSPR and SERS measurements could thus give proof of both …
Optical Properties of Natural and Synthetic Minerals
2015
The results of investigation of optical absorption and photoluminescence (PL) of topaz, beryl and yttrium aluminium garnet crystals doped with different concentrations of transition ions exposed to fast neutron irradiation and electron irradiation are presented. We suppose that irradiation leads to the formation of two types of complex centers: "Me2+-F+ (or F) centre" and complex centers, which consist of a cation vacancy and an impurity (iron, manganese and chromium) ion. Exchange interaction between radiation defects and impurity ions during neutron or electron irradiation gives rise to appearance of additional absorption and luminescence band broadening in investigated crystals.
From Mono- to Poly-Substituted Frameworks: A Way of Tuning the Acidic Character of C-c-H in o-Carborane Derivatives
2009
[EN] The incorporation of iodine atoms onto the boron vertices of the o-carborane framework causes, according to spectroscopic data, a uniform increase in the acidic character of the C-c-H (C-c= cluster carbon) vertices, whereas the incorporation of methyl groups onto the boron vertices of the o-carborane framework reduces their acidity. Methyl groups when attached to boron are electron-withdrawing in boron clusters, whereas iodine atoms bonded to boron act as electron donors. This has been proven on B-methyl and B-iodinated o-carboranes with NMR spectroscopy measurements and DFT calculations of natural bond orbital (NBO) charges. which show a Cumulative buildup of positive cluster only tot…
Structural Characterization of Surfactant-Coated Bimetallic Cobalt/Nickel Nanoclusters by XPS, EXAFS, WAXS, and SAXS
2011
Cobalt nickel bimetallic nanoparticles were synthesized by changing the sequence of the chemical reduction of Co(II) and Ni(II) ions confined in the core of bis(2-ethylhexyl)phosphate (2)., and Ni(DEHP)(2). The reduction was carried out by mixing, sequentially or contemporaneously, fixed amounts of n-heptane solution of Co(DEHP)2 and Ni(DEHP)2 micelles with a solution of sodium borohydride in ethanol at a fixed (reductant)/(total metal) molar ratio. This procedure involves the rapid formation of surfactant-coated nanoparticles, indicated as Co/Ni (Co after Ni), Ni/Co (Ni after Co), and Co + Ni (simultaneous), followed by their slow separation as nanostructures embedded in a sodium bis(2-eth…
Protected but Accessible: Oxygen Activation by a Calixarene-Stabilized Undecagold Cluster
2013
DFT computations show that calixarenes stabilize subnanometer Au11 clusters allowing access of small molecules like O2 to reactive metal sites in the core. Maximum of three dioxygen molecules can bind to the cluster, and they are activated to a superoxo O2(-) state. This study predicts that gold clusters could act as viable oxidation catalysts at ambient conditions based on similar principles as the metal centers in enzymes.
Diastereomeric control of enantioselectivity: evidence for metal cluster catalysis
2014
Enantioselective hydrogenation of tiglic acid effected by diastereomers of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] (P–P* = chiral Walphos diphosphine ligand) strongly supports catalysis by intact Ru3 clusters. A catalytic mechanism involving Ru3 clusters has been established by DFT calculations. peerReviewed
Selecting significant respondents from large audience datasets: The case of the World Hobbit Project
2016
International projects, online questionnaires, or data mining techniques now allow audience researchers to gather very large and complex datasets. But whilst data collection capacity is hugely growing, qualitative analysis, conversely, becomes increasingly difficult to conduct. In this paper, I suggest a strategy that might allow the researcher to manage this complexity. The World Hobbit Project dataset (36,109 cases), including answers to both closed and open-ended questions, was used for this purpose. The strategy proposed here is based on between-methods sequential triangulation, and tries to combine statistical techniques (k-means clustering) with textual analysis. K-means clustering pe…