Search results for "cienza"
showing 10 items of 1535 documents
Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials
2018
New calixarene-based nanosponges (CaNSs), i.e., hyper-reticulated polymers constituted by calixarene monomer units joined by means of bis(1,2,3-trialzolyl)alkyl linkers, were synthesized, characterized and subjected to preliminary tests to assess their supramolecular absorption abilities towards a set of suitable organic guests, selected as pollutant models. The synthesis was accomplished by means of a CuAAC reaction between a tetrakis(propargyloxy)calix[4]arene and an alkyl diazide. The formation of the polymeric network was assessed by means of FTIR and 13C{1H} CP-MAS solid-state NMR techniques, whereas morphological characterization was provided by SEM microghaphy. The materials were pro…
Cambiamenti climatici e diritti umani. Il paradigma della Giustizia climatica e il ruolo delle climate litigations per la protezione dei diritti uman…
2021
In che misura i sempre più diffusi, pervasivi e drammatici impatti dei cambiamenti climatici, che interessano con geometrie variabili tutte le latitudini e longitudini del globo, mettono a rischio la tenuta del sistema dei diritti umani universalmente riconosciuti? La ricerca si pone l'obiettivo di rispondere a tale quesito ragionando su quali sfide essi pongano e su quali siano, nell'attuale panorama, gli strumenti giuridici utili a garantire la piena tutela dei diritti fondamentali nel nuovo contesto clima- alterato. La fondatezza e l’attendibilità delle ricerche scientifiche che avvalorano l’esistenza del cambiamento climatico antropogenico si pongono come presupposto fattuale dell'inter…
Nitrogen-Doped Carbon Nanodots-Ionogels: Preparation, Characterization, and Radical Scavenging Activity
2018
Hybrid diimidazolium-based ionogels were obtained by dispersing nitrogen-doped carbon nanodots (NCNDs) in ionic liquid (IL) solutions and by using dicationic organic salts as gelators. The properties of the NCND-ionogels were studied in terms of thermal stability, mechanical strength, morphology, rheological, and microscopic analyses. Insights into the formation of the hybrid soft material were attained from kinetics of sol-gel phase transition and from estimating the size of the aggregates, obtained from opacity and resonance light-scattering measurements. We demonstrate that, on one hand, NCNDs were able to favor the gel formation both in the presence of gelating and nongelating ILs. On t…
L'analogia physis-techne in Aristotele (Fisica B, 3-9) e la teoria interventistica della causalità
2015
Ho diviso la lettura dei capitoli 3-9 del libro B della Fisica di Aristotele in due momenti: nei capitoli 3-7 viene data la definizione delle quattro cause e si pone il problema se caso e fortuna sono cause del divenire, nei capitoli 8-9 si risolve tale aporia in senso teleologico e si traggono le conclusioni sulla relazione physis-techne. La concezione interventistica della causalità sostiene che c’è uno stretto legame fra causalità e intervento umano in natura: l’idea di una relazione causale fra due eventi (uno che causa e l’altro che è causato) ha come presupposto il concetto di azione intenzionale e nasce dalla riflessione dell’uomo sul proprio operare finalizzato nella realtà. Sebbene…
Definizione e significati della physis in Aristotele a partire dal confronto con la techne Il logos come apertura della physis alla techne in Fisica …
2015
Oltre all' idea della genesi della dottrina delle cause dal confronto fra techne e physis, l’ipotesi che guida questo studio, a tale idea strettamente connessa, è l’interpretazione della techne aristotelica come sussunzione del divenire naturale, e delle sue catene causali, entro l’operare umano in vista di un fine: la similitudine fra techne e physis viene colta da Aristotele nell’essere entrambe movimenti che producono enti imponendo una forma ad una materia adeguata e secondo un piano finalizzato; in entrambi questi processi la causa formale e la causa finale del movimento giungono, da un certo punto di vista, ad identificarsi.
Hydrolytic degradation of PLA/Posidonia Oceanica green composites: A simple model based on starting morpho-chemical properties
2021
Abstract In this work, we studied the degradability of PLA-based biocomposites containing Posidonia Oceanica flour at different loading levels and aspect ratios. Hydrolytic tests were carried out in neutral (pH = 7.4) and alkaline (pH = 10) environment. Time-dependent evolution of some key features, including residual mass and solution uptake, was monitored, and correlated with the changes observed in both morphology and chemical structure of the matrix. The results pointed out that biocomposites degraded much faster than neat PLA in both conditions, up to lose 70% of their initial weight after 1000 h immersion. A complex mechanism was unveiled, evidencing the crucial role of the fillers, c…
Synthesis of cyanoacetic acid by carbon dioxide and electrogenerated acetonitrile anion in undivided cells equipped with sacrificial anodes
2008
The electrochemical synthesis of cyanoacetic acid was performed by cathodic reduction of tetraalkylammonium salts (R4NX) in acetonitrile in undivided cells equipped with sacrificial anodes with concomitant or subsequent addition of carbon dioxide. These syntheses avoid the use of dangerous reagents, yield cyanoacetic acid in moderate faradic yields and confirm that the cathodic reduction of tetraalkylammonium salts in the presence of acetonitrile leads to the formation of the anion CNCH2-.
PHEA‐PLLA: A New Polymer Blend For Tissue Engineering Applications
2011
One of most important features that a material should have in order to be utilized for tissue engineering applications is its biocompatibility and its chemical surface. These properties are required for a high degree of cell adhesion on the scaffold. Poly‐L‐lactid acid (PLLA) is a biocompatible synthetic polymer approved by the Food and Drug Administration for human clinical applications. It has been largely employed, in the last years, as a constituent of surgical and implantable devices. PHEA is a biocompatible water‐soluble synthetic polymer, with a protein‐like structure, whose use as a drug carrier and as starting material for many other biomedical and pharmaceutical applications has b…
Recycling of dry and wet polyamide 6
2002
Recycling of polycondensation polymers can give rise to secondary materials with good mechanical properties only if a careful drying is carried out before the melt reprocessing operations. The presence of humidity provokes the hydrolytic chain scission of the macromolecules and the consequent decrease of molecular weight and properties. In this work, the drying step was substituted by the addition of an antioxidant that is able to protect the macromolecules because it is the autioxidant is more prone to hydrolysis, thus removing the water from the melt. The mechanical properties of polyamide 6 reprocessed more times in wet conditions and in the presence of this stabilizer are even better th…
Characterization of a fiber-reinforced new fully aromatic liquid crystalline polymer
1998
A new rigid liquid crystalline polymer that demonstrates good mechanical and thermomechanical properties and acceptable processing temperature has been recently synthesized and characterized. The melting temperature and some thermomechanical properties do not seem, however, suitable for use in some applications at high temperature or in the presence of aggressive fluids. The use of appropriate inorganic fillers can overcome these shortcomings. In this work the new LCP, polymerized in a bench-scale apparatus, and the same sample filled with carbon fibers are characterized. The properties of the carbon fiber filled LCP are compared with those of another filled wholly aromatic commercial LCP,…