L'Egitto dei Flavi, fornendo sintesi e nuove prospettive d'indagine, vuole ritenersi un pratico strumento riguardante le molteplici informazioni ricavabili dalle fonti provenienti dalla provincia ...romana d'Egitto nel momento di passaggio dalla dinastia giulio-claudia alla nuova dinastia flavia proponendo una revisione d'insieme specie di queste ultime. Nel corso delle indagini si è tentato di mettere a fuoco la provincia d'Egitto durante il periodo di dominazione flavia con l'intento di fornire un compendio e un esame più calibrato dell'organizzazione tecnica ed economica del paese in un periodo storico che ancora parrebbe complesso voler definire nella sua completezza. Tale operazione ha reso necessario partire dalle varie fonti documentarie (papiri, ostraka, epigrafi e tavolette lignee) che portavano testimonianza degli aspetti che si intendeva maggiormente porre in rilievo. I testi esaminati sono pertanto stati attentamente selezionati nel contesto del consistente materiale disponibile.
Eighteen short cores were analyzed for major and trace metals (Al, Fe, Ca, Mg, Mn, Si, K, Ti, Pb, Zn, Cu, Ni, Cr),
210Pb,
137Cs, and other sediment characteristics, so as to describe the chronology ...of pollution and calculate metal concentration factors and fluxes. Substantial evidence was found that trace metal profiles are influenced by anthropogenic sources and by changes in sediment composition. Only Zn presents concentrations (up to 13.1 μmol g
−) and concentration factors (1.3 to 13.2) that can be attributed to heavy contamination. Pb, Cu and Ni, in this order, are less significant. The areal distribution of concentrations and inventories reflects the importance of direct sources, in particular the industrial area of Porto Marghera and the Dese river. The inventories of excess metals, above pre-industrial levels, were determined for each core and the three different parts of the study area, the amounts of Zn accumulated in sediments are 11.0 Mmol, 5.1 Mmol and 0.37 Mmol in the Campalto, S. Erasmo, and Palude di Cona areas, respectively. Ruxes were also calculated and compared with those suggested for the atmospheric delivery by Cochran et al. (1995)b. Atmospheric fluxes of heavy metal contaminants to the Venice Lagoon,
Rapp. Comm. Int. Mer Médit., 34, 136., the atmospheric contribution is predominant or significant in many cases, especially at sites far from the major local inputs. Concentrations and fluxes show a significant increase in the anthropogenic metal supply starting from the second decade of this century, with maximum inputs in the period between the (1930)s and the (1970)s. At some stations a decrease in heavy metal contamination of surficial sediments was found and this could be ascribed to a reduced input of pollutants in recent years.
The employment of two-dimensional materials, as growth substrates or buffer layers, enables the epitaxial growth of layered materials with different crystalline symmetries with a preferential ...crystalline orientation and the synthesis of heterostructures with a large lattice constant mismatch. In this work, we employ single crystalline graphene to modify the sulfurization dynamics of copper foil for the deterministic synthesis of large-area Cu
9
S
5
crystals. Molecular dynamics simulations using the Reax force-field are used to mimic the sulfurization process of a series of different atomistic systems specifically built to understand the role of graphene during the sulphur atom attack over the Cu(111) surface. Cu
9
S
5
flakes show a flat morphology with an average lateral size of hundreds of micrometers. Cu
9
S
5
presents a direct band-gap of 2.5 eV evaluated with light absorption and light emission spectroscopies. Electrical characterization shows that the Cu
9
S
5
crystals present high p-type doping with a hole mobility of 2 cm
2
V
−1
s
−1
.
The employment of two-dimensional materials, as growth substrates or buffer layers, enables the epitaxial growth of layered materials with different crystalline symmetries with a preferential ...crystalline orientation and the synthesis of heterostructures with a large lattice constant mismatch. In this work, we employ single crystalline graphene to modify the sulfurization dynamics of copper foil for the deterministic synthesis of large-area Cu
9
S
5
crystals. Molecular dynamics simulations using the Reax force-field are used to mimic the sulfurization process of a series of different atomistic systems specifically built to understand the role of graphene during the sulphur atom attack over the Cu(111) surface. Cu
9
S
5
flakes show a flat morphology with an average lateral size of hundreds of micrometers. Cu
9
S
5
presents a direct band-gap of 2.5 eV evaluated with light absorption and light emission spectroscopies. Electrical characterization shows that the Cu
9
S
5
crystals present high p-type doping with a hole mobility of 2 cm
2
V
−1
s
−1
.
The employment of 2D materials, as growth substrates or buffer layers, enables the epitaxial growth of layered materials with different crystalline symmetries with a preferential crystalline orientation and the synthesis of heterostructures with a large lattice constant mismatch.
The catalytic mechanism of Burkholderia cepacia lipase (BCL), which catalyzes the enantioselective hydrolysis of racemic esters of primary alcohols, was investigated by modeling the first stage of ...the enzymatic hydrolysis of (S/R)-2-methyl-3-phenyl-propanol (MPP) acetate, using molecular dynamics simulations in a mixed quantum mechanical/molecular mechanical (QM/MM) framework. The free energy surface of the enzyme acylation reaction was computed for both enantiomers. The simulations predict the existence of different reaction free energies that favor the (S)-enantiomer over the (R)-enantiomer by 5 kcal/mol. Analysis of the structural and dynamical aspects of the simulated reactions reveals an unforeseen reorganization of the catalytic triad in the (R)-MPP ester, driven by steric hindrance and involving the residues Asp264 and Glu289. Exploiting the different catalytic role of the above-mentioned acidic residues, we suggest a way to regulate the enantioselectivity of BCL by means of a few judicious point mutations that prevent the formation of the second catalytic triad used in the reaction with the (R)-enantiomer.
The accumulation of PCBs over time was studied in a sediment core collected from Espejo de los Lirios, an ecological reserve located within the heart of Cuatitlan Izcalli, in the Northern part of ...Mexico City Metropolitan Zone. A
210Pb-derived chronology, was used to reconstruct the historical PCB fluxes to the site during ∼84
yr (1911–95). The highest input fluxes occurred in the 1977, after a significant increase after the late 1940s. This trend is clearly the consequence of the increasing emissions that are related to the onset of industrial activities starting from early 1970s. A phase of decrease, after the ban of the use in open systems, ended in 1989 and in 1995, at the time of sampling, the trend was toward a new increase to the highest levels. A reconstruction of PCB atmospheric concentration from sedimentary fluxes is attempted; and the estimate suggests that PCBs concentrations in the air of the Cuautitlán Izcalli seem not of concern. Nonetheless, the contamination levels found in the sediments are relatively high, reaching values above the threshold effect level (TEL) guidelines and, in two cases, close to the probable effect level (PEL) which mean that some adverse effects on the fauna may have occurred all over the time interval represented by the core.
Samples from 18 short sediment cores were analyzed for major and trace metals (Al, Fe, Ca, K, Mg, Mn, Si, Ti, Pb, Zn, Cu, Ni, and Cr),
210
Pb,
137
Cs, total organic carbon, grain size, and ...mineralogical composition to find the record of major environmental changes, either natural or anthropogenic, and to establish their chronologies. Some sediments are characterized by nearly constant composition over time, but others clearly show signs of an increasing marine influence, as an increase of the carbonate contents, after the opening of the Malamocco-Marghera Canal in 1969. These changes sometimes obscure the real pattern of pollutants and tracers, which is revealed by normalization against Al. Zn is the most important contaminant, with concentration factors up to 9.3 times the background level, and the most contaminated sediments are those within a few kilometers from the industrial district of Porto Marghera.
210
Pb activity-depth profiles were used to calculate apparent accumulation rates that provide a basis for the assessment of metal fluxes. The sediments of several sites show a significant increase in anthropogenic metal contamination starting from the second decade of last century, with maximum inputs from 1930 to 1970. The decrease of heavy metal concentrations observed in surficial sediments of some sampling sites could be related to a recent reduction of pollutant inputs.
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