299 research outputs found
dispositivo per l'ancoraggio di pali o paletti infissi nel terreno in prossimita' del ciglio delle scarpate discendenti anche pressoche' verticali.
No full textEffect of Urea and Alkylureas on Micelle Formation by a Nonionic Surfactant with Short Hydrophobic Tail at 25°
No full textEffect of Urea and Alkylureas on Micelle Formation by a Nonionic Surfactant with Short Hydrophobic Tail at 25°
No full textOn the presumed specific interaction of anionic surfactants with nonionic polymers. Aqueous solution of sodium alkylsulfonate in the presence of poly(vinylpyrrolidone): An "excluded volume" effect
No full textSurface tension, viscosity, intradiffusion, and interdiffusion measurements have been performed on aqueous solutions of sodium octyl sulfonate, sodium decyl sulfonate, and sodium undecyl sulfonate, in the presence of poly(vinylpyrrolidone) at 1% why. The experimental measurements for each ternary system were performed in a range of surfactant concentration including the binary critical micelle concentration of the surfactant. The overall picture of the properties studied suggests the absence of a specific interaction between poly(vinylpyrrolidone) and alkylsulfonate surfactants. The experimental diffusion coefficients can be interpreted in terms of an "excluded volume" effect produced by the presence of the polymer in solution
Effect of the addition of a non-ionic surfactant on the complex poly(asparagine)-cationic surfactant
No full textPoly(asparagine) (pAsn) at 0.1wt % in the presence of dodecyltrimethylammonium bromide (DTAB) and pentaoxyethylene octyl ether (C8E5) at 1:1 molar ratio leads to the formation of mixed DTAB/C8E5 micelle-like aggregates onto the polypeptide as a total surfactant critical association concentration (cac) is reached, as revealed by surface tension measurements and NMR chemical shifts. Two-dimensional nuclear Overhauser enhancement spectroscopy (NOESY) capable of revealing spatial relationships among proximal protons has been performed on the pAsn-DTAB-C8E5-water system to study structural details of the surfactant-polypeptide aggregates. NOESY cross-peaks at sample temperature of 298.15 K indicate that the polypeptide interacts with the DTAB/C8E5 micelle-like aggregates. The NOE intermolecular effects also show direct interactions between surfactant and polypeptide in the pAsn-DTAB-water system, whereas no interaction has been revealed in the pAsn-C8E5-water system. Furthermore, the experimental evidence suggest that the DTAB-polypeptide complex is mainly driven by the polar attraction between the two molecule
Il ruolo dell’Architettura nella gestione dei Commons: un’ipotesi per lo “Scugnizzo liberato”.
No full textNel 2013 il Comune di Napoli ha istituito l’Osservatorio sui beni comuni, con quest’atto viene ufficializzata una posizione innovativa, ma anche fortemente controversa, relativa alla gestione di beni di proprietà pubblica o privata da parte di “comunità” che utilizzano questi spazi realizzando un utile sociale. Il numero di Louts del 1994 dal titolo Commons traccia la relazione tra questa questione, di natura economica, politica e sociale e l’architettura. In particolare a Napoli i nove spazi individuati dall’Osservatorio pongono agli architetti nuove domande e, prima tra tutte, come conciliare questa modalità di gestione dal basso, che ha sicuramente il merito di restituire alla comunità luoghi spesso dimenticati e abbandonati, con le esigenze di tutela e conservazione del patrimonio culturale della città. Partendo dal caso dello” scugnizzo liberato” l'intervento proverà a definire un possibile ruolo dell’architettura nel processo di gestione dei Commons
Effect of urea and alkylureas on micelle formation by a nonionic surfactant with short hydrophobic tail at 25 °C
No full textThe effect of urea, N-monomethylurea, and N,N′-dimethylurea on the micellization of the nonionic ethoxylated tenside pentaethyleneglycolmonohexyl ether (C6E5) was investigated through intradiffusion coefficient measurements (Pulsed-gradient spin-echo-NMR method) at 25 °C. The presence of the additive causes, in all cases, an almost linear increase in the critical micellar composition (cmc), while a decrease in the aggregation number occurs. Furthermore, both the monomer-monomer and micelle-micelle interactions increase. The analysis of the intradiffusion coefficients shows the presence of additive molecules in the hydration shell of the tenside, in both its monomeric and micellar forms. A comparison with the results obtained for the water- pentaethyleneglycol (PEG5)-urea or alkylurea systems suggests that the additive molecules are mainly positioned near the tenside ethoxylic chain. The number of alkylurea molecules in the solvation shell of each C6E5 and PEG5 molecule was computed and commented. The experimental cmc values in water-C6E5-urea mixtures are in quite good agreement with those predicted through a molecular thermodynamic model
Enzymatic study for valorization of plant wastes
No full textPlant wastes represent an interesting source of natural polymers such as cellulose. An enzymatic study was carried out with hydrolytic enzymes in order to obtain a high quality fibers from tomato stalks. The total sugars released in the incubation solution were evaluated with Dubois Method. Cellulose, hemicellulose and lignin percentages of obtained products were determined by Van Soest method. SEM was used to evaluate the quality of fibers. The results demonstrated that tested enzymes can be applied in the tomato stalks pulp processing, to improve lignocellulosic material, which can be used as starting material in different industrial sectors
Lignocellulosic fibres from enzyme-treated tomato plants: Characterisation and application in paperboard manufacturing
No full textLignocellulosic raw materials are being utilised in many industrial sectors as a natural source of interesting biopolymers. In the present research, tomato plant agri-waste, were subjected to an enzymatic treatment (pectinase, hemicellulase, xylanase and laccase) with the aim of recovering polymeric matrices contained therein and obtain a good quality fibre. The cellulose content in the enzyme-treated fibres was enriched of 25% compared to the untreated, and a fair reduction in hemicellulose and lignin was registered. Morphological analyses at SEM demonstrated the cleanliness and fibrillation of fibres. Moreover, the thermal profile, water absorption and pulp viscosity of fibres was strongly affected by the composition changes. The paperboard manufactured from an enzymatically treated sample showed increased stiffness when subjected to tensile testing respect to the control. Therefore, the use of enzyme in fibre pulping has a potential application in the design of sustainable materials
Neoliberalism’s public-sector impact: the US and Germany compared
No full textSauer C, Valet P, Roscigno VJ, Wilson G. Neoliberalism’s public-sector impact: the US and Germany compared. In: Warhurst C, Mathieu C, Dwyer RE, eds. The Oxford Handbook of Job Quality. Oxford: Oxford University Press; 2022: 469-485
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