Search results for "Tecnologie"

Selective photocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxaldehyde by polymeric carbon nitride-hydrogen peroxide adduct

2018

Abstract Polymeric carbon nitride-hydrogen peroxide adduct (PCN-H2O2) has been prepared, thoroughly characterised and its application for selective photocatalytic conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxaldehyde (FDC) in aqueous suspension has been studied. The PCN-H2O2 adduct is stable in aqueous suspension under UV and solar irradiation up to 100 °C. It is also stable up to 200 °C if heated in air, while at temperatures close to 300 °C its decomposition takes place. Based on the obtained characterisation data it has been proposed that H2O2 attaches to the non-polymerised carbon nitride species and to the heptazine nitrogen atoms, thus producing strong hydrogen bond…

Degradation of 4-nitrophenol (4-NP) using Fe-TiO2 as a heterogeneous photo-Fenton catalyst

2010

Heterogeneous photocatalysis for selective partial oxidation reactions in aqueous suspension

2018

Heterogeneous photocatalysis for selective partial oxidation reactions in aqueous suspension

Supported H3PW12O40 for 2-propanol (photo-assisted) catalytic dehydration in gas-solid regime: The role of the support and of the pseudo-liquid phase…

2016

Abstract Catalytic and photocatalytic 2-propanol dehydration was carried out by using a supported Keggin heteropolyacid H3PW12O40 (PW12). Binary materials were prepared by impregnation and/or solvothermal treatment by using commercial supports: SiO2 (Mallinckrodt), TiO2 (Evonik P25) and multiwall carbon nanotubes (Sunnano) or home solvothermically prepared SiO2 and TiO2. All the materials have been characterized by X-ray diffraction (XRD), scanning electron microscopy observations (SEM) coupled with EDX microanalysis, specific surface area measurements, diffuse reflectance spectroscopy (DRS), FTIR and Raman spectroscopy. (Photo)catalytic 2-propanol dehydration was studied in gas-solid regim…

La història digital: una certa idea i algunes il·lustracions

2013

A les darreres dècades, les noves tecnologies han fet que els historiadors reconsiderin les formes com investiguen, escriuen i difonen el seu treball. La pretensió d’aquest text és esbossar un marc general al voltant del que significa la història digital, proposant una distinció entre la «història a l’era digital» i «la història digital»: entre els estudiosos que utilitzen certs recursos i eines digitals (processadors de textos, correu electrònic, catàlegs, etcètera) i els acadèmics que desenvolupen una nova comprensió de la història, compromesos amb el paper que les noves tecnologies digitals poden assolir dins l’estudi del passat. Aquest assaig analitza ambdues perspectives, presentant un…

An analysis of through-thickness residual stresses in aluminium FSW butt joints

2006

Abstract In the paper, the results of a wide experimental campaign on friction stir welding (FSW) of aluminum alloys are reported. The attention was focused on the through-thickness residual stresses that occur on aluminum joints, after the welding process. In detail, using the hole-drilling method the residual stresses distribution in the zone close to the tool shoulder border of the joint advancing side, has been investigated; four different aluminum alloys and three different process conditions have been considered. The experimental analysis has shown that unlike traditional welding processes, the residual stresses are negative in the surface of the examined zone, and increase with depth…

Study and characterization of polyphenol oxidase from eggplant (Solanum melongena L.)

2011

ABSTRACT: In this study the catecholase and cresolase activities of eggplant polyphenol oxidase (PPO) were investigated. Enzyme activity was determined by measuring the increase in absorbance using catechol as substrate and 3-methyl-2- benzothiazolinone hydrazone (MBTH) as coupled reagent. The effects of substrate specificity, heat inactivation, temperature, pH, and inhibitors were investigated to understand the enzymatic alteration of ready-to-eat preparations. Browning of vegetables was determined through a colorimeter. Decrease of lightness (L*) and increase of color difference values (ΔE*) were correlated with tissue browning. Antibrowning agents were tested on PPO under the same condit…

Environmental comparison between a hot extrusion process and conventional machining processes through a Life Cycle Assessment approach

2014

Nowadays manufacturing technologies have to be evaluated not only for the technical features they can provide to products, but also considering the environmental perspective as well. As long as the technological feasibility of a given process is guaranteed, processes minimizing resources and energy consumption have to be selected for manufacturing. With respect to this topic, the research studies in the domain of metal processing technologies predominantly focus on conventional material removal processes as milling and turning. Despite some exceptions, many other non-machining technologies, such as metal forming processes, are still not well documented in terms of their energy and resource …

Synthesis of polymer nanogels by electro-Fenton process: investigation of the effect of main operation parameters

2017

Recently, electro-Fenton (EF) process has been shown as a promising, facile, effective, low cost and environmentally-friendly alternative for synthesizing polymer nanogels suitable as biocompatible nanocarriers for emerging biomedical applications. Here, the electrochemically-assisted modification of poly(vinylpyrrolidone) (PVP) by EF process was studied to assess the role of key operation parameters for a precise modulation of polymer crosslinking and its functionalization with [sbnd]COOH and succinimide groups. The dimensions of the nanogels, in terms of hydrodynamic radius (Rh) and weight-average molecular weight (Mw), can be tuned up by controlling the electrolysis time, current density…

Xyloglucan-based hydrogel films for the design of "smart" bandages

2016

A chronic wound is a wound that does not heal in an orderly set of stages and in a predictable amount of time the way most wounds do. Chronic wounds mostly affect people over the age of 60, but a significant proportion is becoming radiation induced chronic wounds caused by cancer radiotherapy. Hydrogels are often used as dressings in the management of a variety of wounds. These materials can help to maintain a moist wound environment, promote natural debridement, hydrate necrotic tissue, absorb slough and exudates.We are developing hydrogel dressings that can enable constant monitoring of selected key parameters through embedded radio-sensors, providing information on the progress of the re…