Search results for "MATERIALS"
showing 10 items of 29608 documents
Palermo 2018 i portali. Architetture e culture della tradizione costruttiva siciliana
2018
Il viaggio tra i portali monumentali è una rivisitazione inedita della città. Fare un giro nel centro storico di Palermo è un vero e proprio viaggio nella storia che solo un occhio attento e preparato comprende. I segni della sua ori- gine sono ancora leggibili, così come le sue trasformazioni sono impresse, nelle strade e nelle facciate di palazzi e chiese. Il fascino di questa città sta forse proprio in queste modificazioni e sovrapposizioni, in questa ricerca del documento che è storia e tecnologia insieme perché la storia si è impressa nella materia che la sostanzia. Lo studio dei portali di Palermo è frutto di una ricerca internazionale che ha per tema la lettura del costruito storico …
Effect of Er3+-doping on 65GeS2-25Ga2S3-10CsCl glass probed by annihilating positrons
2019
Abstract Effect of Er3+-doping resulting in pronounced mid-IR fluorescence functionality was examined first in chalcohalide 65GeS2-25Ga2S3-10CsCl glass using positron annihilation lifetime (PAL) spectroscopy. The detected PAL spectra were reconstructed from unconstrained x2-term analysis employing two-state simple trapping model for one kind of positron trapping free-volume defects, the parameterization being performed at the example of 65GeS2-25Ga2S3-10CsCl glass doped with 0.6 at. % of Er3+. The observed decrease in positron trapping rate was proved to be primary void-evolution process in this Er-activated glass, like in many other chalcogenide glasses affected by rare earth doping. The n…
Positron Surface States on Clean and Oxidized Al and in Surface Vacancies
1983
This Letter reports on the first discrete-lattice calculation of positron surface states on the surfaces of Al. The authors reproduce the observed values and anisotropy of the binding energies on clean surfaces, and predict the surface-state lifetimes. The temperature-independent lateral diffusion constant is calculated. Monovacancies on surfaces are predicted not to trap positrons. The effect of ordered chemisorbed monolayers of oxygen is investigated: Oxidation makes the surface state unstable with respect to positronium emission. Peer reviewed
Fresh-Cut Mangoes: How to Increase Shelf Life by Using Neem Oil Edible Coating
2022
The mango is the most widely cultivated tropical fruit. Fresh-cut mango is very useful, but it is very perishable. The purpose of this study was to highlight the effects of neem oil on fresh-cut mango fruits kept for 9 days at 4 ± 1 °C and 80 ± 5% relative humidity. The neem plant (Azadirachta indica) has numerous antioxidant and antibacterial properties. Despite this, very few studies have been carried out on neem oil added to edible coatings (EC) to retard ripening processes. Two formulations were tested: EC1 (hydroxypropyl methylcellulose + CaCl2) and EC2 (hydroxypropyl methylcellulose + CaCl2 + neem oil), both compared with an untreated sample (control). Physicochemica…
Sponge‐Like Behaviour in Isoreticular Cu(Gly‐His‐X) Peptide‐Based Porous Materials
2015
We report two isoreticular 3D peptide-based porous frameworks formed by coordination of the tripeptides Gly-L-His-Gly and Gly-L-His-L-Lys to Cu(II) which display sponge-like behaviour. These porous materials undergo structural collapse upon evacuation that can be reversed by exposure to water vapour, which permits recovery of the original open channel structure. This is further confirmed by sorption studies that reveal that both solids exhibit selective sorption of H2 O while CO2 adsorption does not result in recovery of the original structures. We also show how the pendant aliphatic amine chains, present in the framework from the introduction of the lysine amino acid in the peptidic backbo…
Influence of the process parameters on the microstructure of a hardfacing coating elaborated by hot isostatic pressing
2019
Hot Isostatic Pressing elaboration of Norem02, an austenitic-ferritic hypereutectoid stainless steel, leads to the formation ofan austenitic matrix with a mixture of acicular M7C 3 and globular M23 C 6 carbides. The sintering tests, carried out by using an AISI304L container, showed that the final microstructure and the carbides’ distribution of the HIPed Norem02 are strongly influencedby the process parameters (heating and cooling rate, sintering time, holding temperature and pressure) and by the particles’ size,microstructure and phase distribution of the initial powder. The morphological, crystallographic and chemical analysis of the sinteredsamples were completed by comprehension of the…
New high-pressure phase and equation of state of Ce2Zr2O8
2012
In this paper we report a new high-pressure rhombohedral phase of Ce2Zr2O8 observed from high-pressure angle-dispersive x-ray diffraction and Raman spectroscopy studies up to nearly 12 GPa. The ambient-pressure cubic phase of Ce2Zr2O8 transforms to a rhombohedral structure beyond 5 GPa with a feeble distortion in the lattice. Pressure evolution of unit-cell volume showed a change in compressibility above 5 GPa. The unit-cell parameters of the high-pressure rhombohedral phase at 12.1 GPa are ah = 14.6791(3) {\AA}, ch = 17.9421(5) {\AA}, V = 3348.1(1) {\AA}3. The structure relation between the parent cubic (P2_13) and rhombohedral (P3_2) phases were obtained by group-subgroup relations. All t…
Partial Discharges in HVDC Cables - The Effect of the Temperature Gradient During Load Transients
2021
The paper investigates the role of the space charge accumulation phenomena in the inception of Partial Discharges (PD) in a defect within the bulk of the dielectrics of a High Voltage Direct Current (HVDC) cable. It is widespread accepted that the number of PD occurring in an HVDC cable during its lifetime is largely less than that under AC voltage stress. This is essentially due to higher values of the voltage between the conductor and the screen needed to trigger PD under a steady DC voltage than the same value under AC stress. Nevertheless, due to the dependency of the electrical conductivity of the insulation on the electric field and temperature, PD in HVDC cables is strongly influence…
Comparison of Post-Weld Treatment of High-Strength Steel Welded Joints in Medium Cycle Fatigue
2010
This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel. The processes investigated are: burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation is on the so-called medium cycle area, i.e. 10 000-500 000 cycles and very high stress ranges. In this area of fatigue design, the use of very high strength steel becomes necessary, since the stress range can exceed the yield-strength of ordinary structural steel, especially when consi…
I Symposium of Elite Performance in Combat Sports
2017
This report presents a summary of the I Symposium of Elite Performance in Combat Sports held in Madrid, May 27, 2017. The symposium, organized by the Faculty of Sport Sciences-INEF of the Polytechnic University of Madrid, aimed to bring science closer to practice. A panel of highly successful athletes involved in karate, fencing, and taekwondo shared their experiences. The speakers presented crucial topics for an optimal preparation and high level performance such as strength training, sport psychology, brain maturation, sports nutrition, competition planning, sport injuries, and perceptual-decision making training.