Single-step preparation of inverse opal titania films by the doctor blade technique

The difficulty to infiltrate solid-state hole semiconductors within micron-thick porous titania films is one of the major limiting factors for the achievement of efficient solid-state dye-sensitized solar cells. It was already shown that through the ordered interconnected pores of an inverse opal, the large surface area of several microns thick titania film can be easily decorated with a dye and filled with a solid-state hole semiconductor. In this paper, we show that ordered inverse opal mesoporous thick films of TiO2 with these characteristics can be obtained by using a slurry of monodispersed polystyrene spheres and a titania-lactate precursor deposited by the doctor blade technique. The mechanism of formation of the inverse opal is also discussed

Developing keratin sponges with tunable morphologies and controlled antioxidant properties induced by doping with polydopamine (PDA) nanoparticles

his work investigates the preparation of wool keratin sponges by freeze-drying procedure starting form keratin aqueous solutions. The study highlights the correlations between process parameters (protein concentration and freezing rate) and the chemical-physical properties of the final sponges. In particular, as the keratin concentration increases from 1 to 20% wt, the mean pore size and the porosity decrease from 62 to 37 mu m and from 94 to 50% respectively, while the chemical stability in physiological conditions increases, as well as the thermal stability and the elastic modulus. On the other hand, the increase of the freezing rate affects the design of sponges that appear as stacked leaflets structures with oriented pores. Moreover, in order to confer to keratin sponges antioxidant properties, polydopamine (PDA) nanoparticles were used as fillers. To this end, PDA nanoparticles of about 130 nm were successfully dispersed in the sponges, bestowing time-dependent anti-oxidant properties on the scaffolds, with no significant modification of sponges morphological structure as well as reduction of the thermal stability and mechanical behaviour

Core-shell graphene oxide-polymer hollow fibers as water filters with enhanced performance and selectivity

Commercial hollow fiber filters for micro-and ultrafiltration are based on size exclusion and do not allow the removal of small molecules such as antibiotics. Here, we demonstrate that a graphene oxide (GO) layer can be firmly immobilized either inside or outside polyethersulfone-polyvinylpyrrolidone hollow fiber (Versatile PES®, hereafter PES) modules and that the resulting core-shell fibers inherits the microfiltration ability of the pristine PES fibers and the adsorption selectivity of GO. GO nanosheets were deposited on the fiber surface by filtration of a GO suspension through a PES cartridge (cut-off 0.1-0.2 μm), then fixed by thermal annealing at 80 °C, rendering the GO coating stably fixed and unsoluble. The filtration cut-off, retention selectivity and efficiency of the resulting inner and outer modified hollow fibers (HF-GO) were tested by performing filtration on water and bovine plasma spiked with bovine serum albumin (BSA, 66 kDa, ≈15 nm size), monodisperse polystyrene nanoparticles (52 nm and 303 nm sizes), with two quinolonic antibiotics (ciprofloxacin and ofloxacin) and rhodamine B (RhB). These tests showed that the microfiltration capability of PES was retained by HF-GO, and in addition the GO coating can capture the molecular contaminants while letting through BSA and smaller polystyrene nanoparticles. Combined XRD, molecular modelling and adsorption experiments show that the separation mechanism does not rely only on physical size exclusion, but involves intercalation of solute molecules between the GO layers

AN APPRAISAL OF BASE ISOLATION FOR LARGE MONUMENTAL BUILDINGS

Traditional techniques for improving the seismic performance of buildings are based either on the increase in strength or in ductility or, sometimes, of both at the same time. This approach, however, can lead to interventions often deemed as too invasive on heritage buildings. An interesting alternative approach consists in the seismic base isolation of this type of buildings. This modern technique acts rather reducing the seismic energy fed into the structure, rather than trying to forcibly increase its strength or its ductility with local reinforcements. The aim of this work is related to the appraisal of available base isolation techniques with reference to the application to large monumental buildings, where several peculiar aspects have to be considered due to the building age, the urban context around these buildings, the remains of previous constructions these buildings might have been built over. All aspects complicating choice of the isolation system and the positioning of the isolation plane. Furthermore, in this work a base isolation intervention exploiting a classical technique of creating the isolation plane is designed and compared with a new proposal that seeks to obtain the isolation plane several meters below the building foundations

Analysis of the impact of surface heat transfer on a new modification of the Angstroem’s method

A new modification of the Angstroem’s method for thermal diffusivity measurement has been developed. This relies on the propagation of harmonic thermal waves with mean value equal to the ambient temperature. The diffusivity is evaluated by relatively simple processing of temperature data, acquired by infrared thermography.The evaluation is based on a mathematical model, in which the heat transfer coefficient at the specimen surface is assumed to be constant. This work is aimed at verifying that assumption. In particular, the effects of natural convection in air are investigated theoretically by numerical simulation. A strategy to improve the test procedure is finally outlined

Base Isolation for large monumental buildings

Italy is one of the countries with the highest number of historical and monumental buildings. At the same time is a country of moderate/high seismic risk. Many of the Italian historical and monumental buildings are large masonry structures dating back to centuries ago, that can be highly vulnerable to earthquakes. One interesting approach for improving their seismic performance consists in seismic base isolation. This modern technique explicates its beneficial effects by adding a controlled source of damping and moving away the structure from the most energetic band of frequency of the soil motion. Dealing with base isolation of monumental buildings implies consideration for several peculiar, multidisciplinary, aspects. These are related to the age of these buildings, to the fact that they might have become part of larger built-up units, or they might have been built over previous buildings the remains of which can be themselves of interest for the cultural heritage. The aim of this work is first related to an evaluation of the main issues related to base isolation of large historical buildings. Subsequently, a tentative base isolation application is presented with reference to a prototypal case study, to better assess the practicality of base isolation when large historic buildings are concerned

Simulazione di moti di convezione naturale all'interno di una cavità confinata contenente una sorgente termica

In questo lavoro viene presentato un modello di calcolo per lo studio dei moti di convezione naturale presenti all’interno di cavità chiuse di forma arbitraria, riscaldate da sorgenti interne sempre di forma arbitraria. Lo scopo è quello di fornire uno strumento per l’integrazione diretta delle equazioni del moto,nella loro forma instazionaria adimensionale. Tale strumento è, in ultima analisi, finalizzato allo studio delle modalità di scambio termico diffusivo – convettivo all’interno di cavità chiuse.In questo articolo è presentata una soluzione originale, finalizzata all’integrazione numerica del campo di moto, attraverso una discretizzazione ai volumi finiti su griglia cartesiana, all’interno di geometrie complesse. Lo schema di calcolo proposto è quindi applicato allo studio di due problemi di scambio termico convettivo, per i quali sono dati sperimentali e risultati numerici ottenuti attraverso codici di calcolo tradizionali. L’analisi dei risultati locali e dei coefficienti globali di scambio termico conferma l’accuratezza del metodo di calcolo

Caratterizzazione di sedimenti da dragaggio: valutazione della mobilit\ue0 di inquinanti inorganici, e degli effetti del trattamento di Soil Washing

Nell\u2019ambito della caratterizzazione di fanghi da dragaggio portuali, ci si \ue8 occupati di valutare la mobilit\ue0 degli inquinanti inorganici presenti. Si \ue8 lavorato su sedimenti reali e sui prodotti in uscita dal trattamento di Soil Washing. Si \ue8 operato tramite test di cessione, a pH controllato ed a percolazione, per valutare la lisciviabilit\ue0 delle componenti inorganiche in processi analoghi a quelli che subiscono i sedimenti una volta stoccati nell\u2019ambiente. Si \ue8 inteso valutare l\u2019effetto del trattamento sulla mobilit\ue0 degli inquinanti. Questo permette di valutare la pericolosit\ue0 dei materiali, passando dall\u2019inquadramento nelle normative per gli inquinanti nei suoli a quelle per gli eluati per l\u2019ammissibilit\ue0 in discarica dei rifiuti inerti o non pericolos

Caratterizzazione di fanghi da dragaggio tramite test di cessione: mobilit\ue0 degli inquinanti inorganici

In questo lavoro ci si \ue8 occupati, nell\u2019ambito della caratterizzazione di fanghi da dragaggio portuali, di valutare la mobilit\ue0 degli inquinanti inorganici presenti. Si \ue8 lavorato su un sedimento reale. Si \ue8 operato tramite test di cessione, a pH controllato ed a percolazione, per valutare la lisciviabilit\ue0 delle componenti inorganiche in processi analoghi a quelli che possono subire i sedimenti una volta stoccati nell\u2019ambiente. Uno dei trattamenti possibili sui sedimenti per migliorarne le caratteristiche in funzione del riutilizzo \ue8 il Soil Washing, si \ue8 quindi adottata la procedura di caratterizzazione sul sedimento in ingresso al trattamento e sui prodotti in uscita (sabbie e fini). In questo modo \ue8 possibile valutare gli effetti del trattamento sulla mobilit\ue0 degli inquinanti. Questo permette inoltre di valutare la pericolosit\ue0 dei materiali, passando dall\u2019inquadramento nelle normative per gli inquinanti nei suoli a quelle per gli eluati per l\u2019ammissibilit\ue0 in discarica dei rifiuti inerti o non pericolosi. La matrice influenza i risultati di questi test, ed \ue8 quindi importante effettuarli su campioni reali