177,345 research outputs found
Il luogo della prestazione, Il trasferimento del lavoratore
No full textIl contributo analizza la disciplina legislativa del trasferimento del lavorator
Il lavoro autonomo e le libere professioni nella legislazione italiana sul lavoro degli stranieri
No full textIL contributo esamina la disciplina giuridica prevista dalla legisalzione italiana per i lavoratori autonomi stranier
Effect of the Support on the Formation of FeCo Alloy Nanoparticles in an SBA-16 Mesoporous Silica Matrix: An X-ray Absorption Spectroscopy Study
No full textA series of nanocomposites consisting of FeCo alloy nanoparticles supported on a three-dimensional cubic mesoporous silica matrix (SBA-16) were prepared by wet impregnation of the matrix with a solution of Fe and Co nitrates. FeCo alloy nanoparticles were obtained by heat treatment at 800 °C in reducing atmosphere of the impregnated SBA-16 previously calcined at 500 °C. Three different SBA-16 types were used as a support of the nanophase. The influence of the matrix on the absorption of Fe and Co ions was investigated using X-ray diffraction and X-ray absorption spectroscopy. In particular, extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) techniques at the Fe and Co K-edges were used in order to identify the intermediate products before reduction and to study the formation of the bcc FeCo alloy, which cannot be assessed unambiguously using X-ray diffraction. An important influence of the matrix has been observed in the phases formed before reduction, in the size of nanoparticles, and in the oxidation of the FeCo alloy nanoparticles
Insights into the Structure of Dot@Rod and Dot@Octapod CdSe@CdS Heterostructures
No full textCdSe@CdS dot@rods with diameter around 6 nm and length of either
20, 27, or 30 nm and dot@octapods with pod diameters of ?15 nm and lengths of ?50
nm were investigated by X-ray absorption spectroscopy. These heterostructures are
prepared by seed-mediated routes, where the structure, composition, and morphology of
the CdSe nanocrystals used as a seed play key roles in directing the growth of the second
semiconducting domain. The local structural environment of all the elements in the
CdSe@CdS heterostructures was investigated at the Cd, S, and Se K-edges by taking
advantage of the selectivity of X-ray absorption spectroscopy, and was compared to pure
reference compounds. We found that the structural features of dot@rods are
independent of the size of the rods. These structures can be described as made of a
CdSe dot and a CdS rod, both in the wurtzite phase with a high crystallinity of both the
core and the rod. This result supports the effectiveness of high temperature colloidal
synthesis in promoting the formation of core@shell nanocrystals with very low
defectivity. On the other hand, data on the CdSe@CdS with octapod morphology suggest the occurrence of a core composed of
a CdSe cubic sphalerite phase with eight pods made of CdS wurtzite phase. Our findings are compared to current models
proposed for the design of functional heterostructures with controlled nanoarchitecture
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
SYNTHESIS AND LAXS INVESTIGATION OF SOME 1-(D-3-MERCAPTO-2-METHYLPROPIONYL)-L-PROLINE AMORPHOUS COMPLEXES WITH C0(II), Ni(II), Zn(II), Cd(II)
No full textAbstract: Four amorphous metal complexes with 1-(D-3-mercapto-2-methylpropionyl)-L-proline (L) with general formula Na2ML2 . nH2O (M = Co, n = 14; M = Ni, n = 4; M = Zn. n = 4; M = Cd. n = 7) have been synthesized. LAXS (large angle X-ray scattering) provided information on the local order around the metal(II) ions. A 2:1 ratio between ligand and all examined metal ions was found. A tetrahedral configuration around zinc and cadmium ions has been found with two sulphur and two amidic oxygen atoms bonded to the metals. For nickel and cobalt complexes an octahedral configuration has been found with two water molecules bonded to the metal in axial position and two ligand molecules bonded via sulphur and amidic oxygen in equatorial position
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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