Antibacterial effect of zinc oxide-based nanomaterials on environmental biodeteriogens affecting historical buildings

The colonization of microorganisms and their subsequent interaction with stone substrates under different environmental conditions encourage deterioration of materials by multiple mechanisms resulting in changes in the original color, appearance and durability. One of the emerging alternatives to remedy biodeterioration is nanotechnology, thanks to nanoparticle properties such as small size, no-toxicity, high photo-reactivity, and low impact on the environment. This study highlighted the effects of ZnO-based nanomaterials of two bacteria genera isolated from the Temple of Concordia (Agrigento’s Valley of the Temples in Sicily, Italy) that are involved in biodeterioration processes. The antimicrobial activities of ZnO-nanorods (Zn-NRs) and graphene nanoplatelets decorated with Zn-NRs (ZNGs) were evaluated against the Gram positive Arthrobacter aurescens and two isolates of the Gram negative Achromobacter spanius. ZNGs demonstrated high antibacterial and antibiofilm activities on several substrates such as stones with different porosity. In the case of ZNGs, a marked time- and dose-dependent bactericidal effect was highlighted against all bacterial species. Therefore, these nanomaterials represent a promising tool for developing biocompatible materials that can be exploited for the conservation of cultural heritage. These nanostructures can be successfully applied without releasing toxic compounds, thus spreading their usability

L’architettura degli spazi ritrovati. La ex Ceme di Latina

Latina è una città di fondazione che nonostante la sua giovane età vanta un patrimonio industriale dismesso rilevante. Si ritiene doverosa una riflessione sulla gestione di questo e su un suo possibile riuso per la valorizzazione architettonica non sono del singolo edificio ma anche del contesto urbano in cui esso si trova. I siti presenti sul territorio sono tanti e diversi per conformazione, posizione, uso e storia. Il caso studio che si propone, è quello di una piccola fabbrica, la ex CEME posta in prossimità del centro cittadino. I caratteri architettonici, la spazialità interna unitaria e la strategica posizione la rendono adatta a nuove proposte per creare un dialogo con l’intorno, di scuole, università e attrezzature pubbliche. Un centro culturale per l’arte e l’esposizione si propone rispettoso all’interno di ex capannoni industriali. La proposta avanzata mira a valorizzare il manufatto mantenendone le caratteristiche architettoniche. Il nuovo intervento si contrappone al vecchio senza dominarlo ma creando una sinergia temporale fra passato e presente, che attiva una nuova e diversa relazione con il resto della città rigenerandone una sua parte

Electromagnetic properties of composites containing graphite nanoplatelets at radio frequency

The effect of three different carbon-based nano and microfillers on the electromagnetic (EM) performance of polymeric composites was examined through the measurement of the effective complex permittivity in the frequency range from 8.2 to 18 GHz. Results show that polymeric composites based on graphene nanoplatelets are much more easily processable than composites filled with carbon nanotubes, while still retaining much of the EM performance over the investigated frequency band, as well as being light weight. (C) 2011 Elsevier Ltd. All rights reserved

Bioaccumulation Experiments in Mussels Contaminated with the Food-Borne Pathogen Arcobacter butzleri: Preliminary Data for Risk Assessment

The aim of this study was to evaluate, at a laboratory scale, the ability of this microorganism to grow in seawater and bioaccumulate in mussels (Mytilus galloprovincialis) maintained in constantly aerated tanks, containing twenty litres of artificial seawater. Three concentrations of A. butzleri LMG 10828T were tested (about 5×106 CFU/mL, 5×104 CFU/mL, and 5×102 CFU/mL). Following contamination, enumeration of A. butzleri was performed from water and mussels each day, for up to 96 h. Three contamination experiments with artificial seawater in absence of mussels were also performed in the same manner. In the experiments with mussels, A. butzleri declined in water of approximately 1 log every 24 h from the contamination. In artificial seawater without mussels the concentration of A. butzleri remained on the same logarithmic level in the first 48 h and then decreased of about 1 log every 24 hours. In mussels, the concentration was approximately 2 log lower than the exposition level after 24 h from the contamination, and then it decreased exponentially of 1 log every 24 h. Our findings suggest that in the experimental conditions tested A. butzleri is neither able to effectively grow in seawater nor bioaccumulate in mussels, at least in the free and cultivable form

Direct Parametric Maps Estimation from Dynamic PET Data: An Iterated Conditional Modes Approach

We propose and test a novel approach for direct parametric image reconstruction of dynamic PET data. We present a theoretical description of the problem of PET direct parametric maps estimation as an inference problem, from a probabilistic point of view, and we derive a simple iterative algorithm, based on the Iterated Conditional Mode (ICM) framework, which exploits the simplicity of a two-step optimization and the efficiency of an analytic method for estimating kinetic parameters from a nonlinear compartmental model. The resulting method is general enough to be flexible to an arbitrary choice of the kinetic model, and unlike many other solutions, it is capable to deal with nonlinear compartmental models without the need for linearization. We tested its performance on a two-tissue compartment model, including an analytical solution to the kinetic parameters evaluation, based on an auxiliary parameter set, with the aim of reducing computation errors and approximations. The new method is tested on simulated and clinical data. Simulation analysis led to the conclusion that the proposed algorithm gives a good estimation of the kinetic parameters in any noise condition. Furthermore, the application of the proposed method to clinical data gave promising results for further studies

Accelerated PET kinetic maps estimation by analytic fitting method

In this work, we propose and test a new approach for non-linear kinetic parameters' estimation from dynamic PET data. A technique is discussed, to derive an analytical closed-form expression of the compartmental model used for kinetic parameters' evaluation, using an auxiliary parameter set, with the aim of reducing the computational burden and speeding up the fitting of these complex mathematical expressions to noisy TACs. Two alternative algorithms based on numeric calculations are considered and compared to the new proposal. We perform a simulation study aimed at (i) assessing agreement between the proposed method and other conventional ways of implementing compartmental model fitting, and (ii) quantifying the reduction in computational time required for convergence. It results in a speed-up factor of ∼120 when compared to a fully numeric version, or ∼38, with respect to a more conventional implementation, while converging to very similar values for the estimated model parameters. The proposed method is also tested on dynamic 3D PET clinical data of four control subjects. The results obtained supported those of the simulation study, and provided input and promising perspectives for the application of the proposed technique in clinical practice

Piezo-resistive properties of graphene based PVDF composite films for strain sensing

Graphene based polyvinylidene fluoride (PVDF)composite films have been produced and characterized in orderto investigate their piezo-resistive properties. To this purpose, anew production process has been developed, with the aim offabricating at low cost PVDF films filled with graphenenanoplatelets (GNPs). The produced films, having a GNPcontent of 1.5%wt and 2% wt, have been characterized frommorpholocial and chemical points of view. Moreover, theirpiezo-resistive properties have been investigated both in staticand cyclic conditions. The produced films show a stable andrepeatable response to the applied strain. A sensitivity of 15 hasbeen measured for the PVDF/GNP film filled at 1.5% wt,corresponding to an applied strain of 1.5

Graphite nanoplatelets and Caenorhabditis elegans: Insights from an in vivo model

We evaluated the toxicity of graphite nanoplatelets (GNPs) in the model organism Caenorhabditis elegans. The GNPs resulted nontoxic by measuring longevity as well as reproductive capability end points. An imaging technique based on Fourier transform infrared spectroscopy (FT-IR) mapping was also developed to analyze the GNPs spatial distribution inside the nematodes. Conflicting reports on the in vitro antimicrobial properties of graphene-based nanomaterials prompted us to challenge the host-pathogen system C. elegans-Pseudomonas aeruginosa to assess these findings through an in vivo model. © 2012 American Chemical Society