Search results for "Clusters"
showing 10 items of 1274 documents
Marginalità e bioeconomia per lo sviluppo regionale
2014
La bioeconomia si riferisce ad un sistema che si fonda sull'uso intelligente delle risorse biologiche e rinnovabili provenienti dalla terra e dal mare come input industriali e della produzione di alimenti. La Commissione Europea, facendo seguito al lungo dibattito e al percorso effettuato negli ultimi anni sulla strada della sostenibilità, ha approvato la Strategia per l'innovazione per una crescita sostenibile e una bioeconomia per l'Europa. Il lavoro si propone di approfondire come la marginalità territoriale collegata alle disparità socio-economiche, possa essere elemento di vantaggio per la sfida proposta dalla bioeconomia in aree marginali come la Sicilia che hanno le potenzialità di c…
MARGINALITÀ E BIOECONOMIA PER LO SVILUPPO REGIONALE
2013
L'analisi dell'interazioni fra ecosistema e società assume un ruolo rilevante nello studio del sistema economico. La bioeconomia si riferisce ad un sistema che si fonda sull'uso intelligente delle risorse biologiche e rinnovabili provenienti dalla terra e dal mare come input industriali e della produzione di alimenti e mangimi. La bioeconomia, inoltre, comprende l'uso di rifiuti organici e di processi fondati su bioprodotti per un comparto industriale sostenibile. La Commissione Europa, facendo seguito al lungo dibattito e al percorso effettuato negli ultimi anni sulla strada della sostenibilità , ha approvato la strategia per L' innovazione per una crescita sostenibile: una bioeconomia per…
Transport of recoil atoms in a stream of liquid-air-cooled pure helium
1974
Abstract Pure commercial helium cooled down to the temperature of liquid air (80 K) has been used for rapid transportation of recoil atoms over distances as long as 10 m. Transport efficiencies of several tens of per cent have been obtained for recoil atoms resulting from alpha decay or from decay by fission. The angle of divergence of the beam of recoil atoms at the exit of the transport capillary is measured to be (11±2)° for particles of mass number A = 211. Experimental results are discussed in terms of thermal diffusion. The elimination of carrier vapors will probably simplify the use of the helium-jet technique in on-line mass separators.
Simple Nuclear Structure inCd111–129from Atomic Isomer Shifts
2016
Isomer shifts have been determined in ^{111-129}Cd by high-resolution laser spectroscopy at CERN-ISOLDE. The corresponding mean square charge-radii changes, from the 1/2^{+} and the 3/2^{+} ground states to the 11/2^{-} isomers, have been found to follow a distinct parabolic dependence as a function of the atomic mass number. Since the isomers have been previously associated with simplicity due to the linear mass dependence of their quadrupole moments, the regularity of the isomer shifts suggests a higher order of symmetry affecting the ground states in addition. A comprehensive description assuming nuclear deformation is found to accurately reproduce the radii differences in conjunction wi…
The ultrafast dynamics and conductivity of photoexcited graphene at different Fermi energies
2017
The ultrafast dynamics and conductivity of photoexcited graphene can be explained using solely electronic effects.
Cubic aromaticity in ligand-stabilized doped Au superatoms
2021
The magnetic response of valence electrons in doped gold-based [M@Au8L8]q superatoms (M = Pd, Pt, Ag, Au, Cd, Hg, Ir, and Rh; L = PPh3; and q = 0, +1, +2) is studied by calculating the gauge including magnetically induced currents (GIMIC) in the framework of the auxiliary density functional theory. The studied systems include 24 different combinations of the dopant, total cluster charge, and cluster structure (cubic-like or oblate). The magnetically induced currents (both diatropic and paratropic) are shown to be sensitive to the atomic structure of clusters, the number of superatomic electrons, and the chemical nature of the dopant metal. Among the cubic-like structures, the strongest arom…
Support work function as a descriptor and predictor for the charge and morphology of deposited Au nanoparticles.
2020
We show, using density functional theory calculations, that the charge, magnetic moment, and morphology of deposited Au nanoclusters can be tuned widely by doping the oxide support with aliovalent cations and anions. As model systems, we have considered Aun (n = 1, 2, or 20) deposited on doped MgO and MgO/Mo supports. The supports have been substitutionally doped with varying concentrations θ of F, Al, N, Na, or Li. At θ = 2.78%, by varying the dopant species, we are able to tune the charge of the Au monomer between −0.84e and +0.21e, the Au dimer between −0.87e and −0.16e, and, most interestingly, Au20 between −3.97e and +0.49e. These ranges can be further extended by varying θ. These chan…
Highly Robust but Surface‐Active: An N‐Heterocyclic Carbene‐Stabilized Au 25 Nanocluster
2019
Surface organic ligands play a critical role in stabilizing atomically precise metal nanoclusters in solutions. However, it is still challenging to prepare highly robust ligated metal nanoclusters that are surface-active for liquid-phase catalysis without any pre-treatment. Now, an N-heterocyclic carbene-stabilized Au25 nanocluster with high thermal and air stabilities is presented as a homogenous catalyst for cycloisomerization of alkynyl amines to indoles. The nanocluster, characterized as [Au25 (i Pr2 -bimy)10 Br7 ]2+ (i Pr2 -bimy=1,3-diisopropylbenzimidazolin-2-ylidene) (1), was synthesized by direct reduction of AuSMe2 Cl and i Pr2 -bimyAuBr with NaBH4 in one pot. X-ray crystallization…
The wet synthesis and quantification of ligand-free sub-nanometric Au clusters in solid matrices.
2017
© The Royal Society of Chemistry. The synthesis of ligand-free sub-nanometric metal clusters on a large scale suffers typically from very low yields (15% yields, as unambiguously determined using a very simple and extremely sensitive analytical reaction test.
Helium and Argon Line Broadening in the nu2 Band of CH4
2004
Abstract The spectra of the gaseous mixtures CH 4 –He and CH 4 –Ar were obtained in the spectral region 1400–1750 cm −1 with a resolution up to 0.003 cm −1 . Helium and argon pressure broadenings for the vibration–rotation lines of the ν 2 band of CH 4 have been estimated at room temperature for some lines in the P , Q , and R branches. These values were also calculated using the theoretical approach developed by Robert and Bonamy, extended to the case of tetrahedral molecules. The helium data have been found to be in a satisfactory agreement whereas a divergence of calculated and measured broadening coefficients has been evidenced in the case of argon. Simulations of the ν 2 band shapes of…