Search results for "microscopi"

Application of Tunable-Slip Boundary Conditions in Particle-Based Simulations

2014

Compared to macroscopic systems, fluids on the micro- and nanoscales have a larger surface-to-volume ratio, thus the boundary condition becomes crucial in determining the fluid properties. No-slip boundary condition has been applied successfully to wide ranges of macroscopic phenomena, but its validity in microscopic scale is questionable. A more realistic description is that the flow exhibits slippage at the surface, which can be characterized by a Navier slip length. We present a tunable-slip method by implementing Navier boundary condition in particle-based computer simulations (Dissipative Particle Dynamics as an example). To demonstrate the validity and versatility of our method, we ha…

A Methodology to Deduce the Microstructural Spatial Deformation of Polycrystalline Structures: Application to the Alloy 600

2009

Studying the corrosion of the alloy 600, under water pressure, is of high importance to understand the ageing process of pressurized water reactors. Today, the impact of the oxide growth on the mechanical properties of nickel alloys is a challenge. The surface analysis and the quantification of the local deformation are key factors to deduce the surface damage of the substrate produced by corrosion. Here, we introduce a new methodology to determine the deformation distribution of the alloy 600 by using polycrystalline samples. The method is based on nanopads disposed on the surface samples, which allow a mapping, at the microscopic scale, of the spatial deformation. We applied to the sample…

Resine epossidiche: studio delle proprietà microscopiche mediante NMR in stato solido

2012

Two New Retigerane-Type Sesterterpenoids from the Lichen Leprocaulon microscopicum

2016

International audience; Two new sesterterpenes, 1 and 2, have been isolated from the lichen Leprocaulon microscopicum. In addition to classic chromatographic methods, a liquid-liquid chromatography technique, namely centrifugal partition chromatography (CPC) was applied for the purification of compound 2. The structures were determined by analyses of mass spectrometry and 1D- and 2D-NMR data. The relative configuration of the isolated compounds was assigned on the basis of 2D-NOESY experiments. The two compounds possess a rare pentacyclic carbon skeleton typical for lichen metabolism, and quite unusual in the vegetal kingdom.

Evaluation of reverse transcription and polymerase chain reaction (RT/PCR) for the detection of rotaviruses: applications of the assay.

1996

Summary Our aim was to evaluate the reverse transcription and polymerase chain reaction (RT/PCR) technique for the detection of rotavirus shedding by infected children as a routine diagnostic procedure, in comparison to the enzyme-linked immunosorbent assay (ELISA), electron microscopy (EM) and polyacrylamide gel etectrophoresis (PAGE) of rotavirus double stranded RNA. Two-hundred and twenty stool specimens were collected from infants and young children with diarrhoea, and 10–20% faecal suspensions were made. Several methods of rotavirus dsRNA extraction were assayed. Electrophoretic analysis of viral RNA was carried out on 10% polyacrylamide gols followed by silver staining. RT/PCR was per…

Morfologia ed analisi delle immagini applicate allo studio dei bitumi modificati con polimeri

2009

Vengono presentati i risultati di uno studio di laboratorio condotto su campioni di bitume modificato con diversi tipi di polimeri e precisamente Stirene-butadienestirene (SBS), Etilen-vinilacetato (EVA) ed etilen-butilacrilato (EBA), le cui proprietà fisico-chimiche vengono riportate nell’articolo.

COMPARISON BETWEEN VEHICLE SPEED PROFILES ACQUIRED BY DIFFERENTIAL GPS AND UAV

2014

Traffic microscopic simulation models are able to represent traffic conditions and their evolution over time. They take into account the geometrical aspects of transport infrastructures, driver behavior and, step by step, the vehicles’ movements on the road network. The most widespread applications of these models are referred to accident management, route guidance problems (possibility of evaluating control strategies in real time), adaptive control of traffic-light and ramp metering (management and control of the ramps and flow). To accomplish this goal observational data of vehicles’ kinematic characteristics have to be acquired. These elements are not always easily available. In scienti…

Il restauro della lunetta dipinta: "Cristo e l'Eterno ai lati del mondo"

2015

Oggetto del nostro contributo è lo studio ed il restauro della lunetta dipinta raffigurante “Cristo e l’Eterno ai lati del mondo” realizzata da Simone de Wobreck nel 1562. L’intervento è stato realizzato come prova abilitante alla professione nell’ambito delle attività laboratoriali del Cdl in Conservazione e Restauro dei Beni Culturali, dell’Università di Palermo, con la direzione della Galleria Regionale di Palazzo Abatellis [1]. Di particolare interesse è stato lo studio dell’opera in relazione alla tecnica esecutiva utilizzata dall’autore, allo stato di conservazione ed ai precedenti interventi che l’opera ha subito negli anni. La tavola dipinta raffigura Cristo e l’Eterno ai lati del m…

Heterogeneous shear elasticity of glasses: the origin of the boson peak

2013

The local elasticity of glasses is known to be inhomogeneous on a microscopic scale compared to that of crystalline materials. Their vibrational spectrum strongly deviates from that expected from Debye's elasticity theory: The density of states deviates from Debye's law, the sound velocity shows a negative dispersion in the boson-peak frequency regime and there is a strong increase of the sound attenuation near the boson-peak frequency. By comparing a mean-field theory of shear-elastic heterogeneity with a large-scale simulation of a soft-sphere glass we demonstrate that the observed anomalies in glasses are caused by elastic heterogeneity. By observing that the macroscopic bulk modulus is …

La utilización de marfil de cachalote en el Calcolítico de Portugal

2013

Scientific analysis were undertaken within a research project concerning ivory objects from the Chalcolithic to Early Bronze Age of the Iberian Peninsula. In several of the analyses of objects from Portuguese Estremadura, especially V-perforated buttons, we could detect for the first time the presence of sperm whale ivory. This highlights the advantage and necessity of scientific analysis of ivory. It also clearly demonstrates that not all ivory used was ivory from African or Asian elephants, but we also did find ivory from the extinct Elephas antiquus, the hippopotamus and in this case sperm-whale. Thus, already in the Chalcolithic the raw material provenience was highly diverse, which in …