Plasma Activation of Copper Nanowires Arrays for Electrocatalytic Sensing of Nitrate in Food and Water

Electrochemical methods for nitrate detection are very attractive since they are suitable for in-field and decentralized monitoring. Copper electrodes are often used to this aim as this metal presents interesting electrocatalytic properties towards nitrate reduction. In this research, we study improvements in the electrochemical analysis of nitrate in natural water and food by taking advantage of the detection capabilities of ensembles of copper nanowire electrodes (CuWNEEs). These electrodes are prepared via template electrodeposition of copper within the nanopores of track-etched polycarbonate (PC) membranes. A critical step in the preparation of these sensors is the removal of the template. Here, we applied the combination of chemical etching with atmospheric plasma cleaning which proved suitable for improving the performance of the nanostructured copper electrode. Analytical results obtained with the CuWNEE sensor for nitrate analyses in river water samples compare satisfactorily with those achieved by standard chromatographic or spectroscopic methods. Experimental results concerning the application of the CuWNEEs for nitrate analysis in food samples are also presented and discussed, with focus on nitrate detection in leafy vegetables

Method for generating an atmospheric plasma jet and atmospheric plasma minitorch device

A method and a device for generating a plasma in atmospheric-pressure, low-temperature conditions are described herein. The device described for the generation of the plasma comprises a first pair of electrodes, each of which separated by a dielectric layer and externally positioned with respect to a tubular duct where the gas flows, and a second pair of electrodes, also in this case each of which separated by a dielectric layer and externally positioned with respect to said tubular duct where the same gas flows downstream with respect to the first pair with respect to the direction of the flow. A high-frequency excitation is applied to the first pair of electrodes while a Radio-Frequency excitation is applied to the second pair of electrodes. The plasma generated in this manner emerges from the gas flow at the outlet of the transport duct. The high-frequency excitation can be applied in pulse trains and the Radio-Frequency generator is substantially activated in said pulse trains for the purpose of limiting the thermal load on the treated substrate. Chemical precursors and reagents can be added to the plasma as vapors or aerosols by means of a central transport duct coaxial with the tubular duct for the gas

Comparative Study Between Ammonium Phosphate and Ethyl Silicate Towards Conservation of Prehistoric Paintings in the Magura Cave (Bulgaria)

This study aimed at evaluating the effectiveness and the compatibility of two alternative treatments, in view of their possible use for conservation of prehistoric paintings in the Magura cave (Bulgaria). The paintings are made of bat guano applied over limestone; therefore, two sets of laboratory specimens were considered: stone specimens and stone specimens covered with a layer of sterilized bat guano. The two investigated treatments were a commercial product based on ethyl silicate (“ES”) and a solution of diammonium hydrogen phosphate (“DAP”), aimed at forming calcium phosphates. The results of the study indicated that both treatments were able to increase the mechanical properties of stone, the increase being higher for “DAP”. Both consolidants caused acceptable color changes, but the “ES” treatment significantly decreased stone wettability, water absorption, and water vapor permeability, while the “DAP” treatment slightly affected those properties. In the stone + guano specimens, the presence of the guano layer affected the penetration of the consolidants, thus partly reducing their effectiveness. Compared to the stone samples, the guano layer experienced a more intense color change, alongside visible cracking. However, the adopted methodology to replicate the cave paintings was not completely successful, as the so-deposited guano layer was very prone to detachment when dry, unlike cave paintings. Future work will be dedicated to assessing the consolidant performance onto samples that resemble even more closely the conditions of the cave paintings, by improving the methodology for the guano layer deposition and by contaminating specimens with soluble salts before consolidant application

A hybrid additive manufacturing platform to create bulk and surface composition gradients on scaffolds for tissue regeneration

Scaffolds with gradients of physico-chemical properties and controlled 3D architectures are crucial for engineering complex tissues. These can be produced using multi-material additive manufacturing (AM) techniques. However, they typically only achieve discrete gradients using separate printheads to vary compositions. Achieving continuous composition gradients, to better mimic tissues, requires material dosing and mixing controls. No such AM solution exists for most biomaterials. Existing AM techniques also cannot selectively modify scaffold surfaces to locally stimulate cell adhesion. A hybrid AM solution to cover these needs is reported here. A novel dosing- and mixing-enabled, dual-material printhead and an atmospheric pressure plasma jet to selectively activate/coat scaffold filaments during manufacturing were combined on one platform. Continuous composition gradients in both 2D hydrogels and 3D thermoplastic scaffolds were fabricated. An improvement in mechanical properties of continuous gradients compared to discrete gradients in the 3D scaffolds, and the ability to selectively enhance cell adhesion were demonstrated

Assessment of plasma torches as innovative tool for cleaning of historical stone materials

none11siCleaning of historical stone surfaces has always been a challenging task, moreover in the last decades arose new restorations issues such as the need to remove aged conservation polymeric materials to avoid further damage. Different cleaning methodologies flourished in the past, mostly based on chemical, mechanical methods and on laser technology too. Nevertheless, these methodologies could not be so efficient in the removal of epoxy resins, acrylic polymers and hydrophobic siloxanes, because of their low solubility in solvents when aged or their high adhesion with the substrate. More recently, atmospheric plasma has been tested for such application even if it is not yet widely applied due to the lack of knowledge about possible side-effects on the artefacts. In the present work, assessment of three commercial atmospheric plasma devices (plasma torches) illustrated the potentialities and drawbacks of polymers’ removal from stone surface. Commercial epoxy resins, acrylic polymers and hydrophobic siloxanes were chosen for the removal test by plasma devices. Physical and chemical effects on the stone surface and the process efficiency were investigated by means of macro- and microscopic observations, preferring, when possible, non-invasive techniques and consolidated methodologies in the field of Stone Conservation Science. An introductory experimentation on coated Si specimen has allowed to find the proper working parameters, i.e. working distance, exposure time, to have an effective removal. The experimentation conducted on different lithic substrate, coated with the commercial protective, has showed that commercial devices are effective in the removal of epoxy and acrylic coatings via chemical and physical interactions. On the contrary, the removal of siloxane products is incomplete, because of the high stability of the bond Si–O in the back bone, which is not affected by the plasma. In general, the present trials highlighted that DBD apparatus used does not promote any macroscopic effects on the polymeric coating, while arc discharge ones guarantee satisfactory results. According to these preliminary trials, it was clearly evidenced that plasma is a potential cleaning tool, despite DBD systems need higher power or arc discharge needs treatment temperature mitigation and to avoid the deposition of metallic drops on the surface of the object due to electrode deterioration.mixedVoltolina, Stefano; Nodari, Luca; Aibéo, Cristina; Egel, Ellen; Pamplona, Marisa; Simon, Stefan; Falzacappa, Emanuele Verga; Scopece, Paolo; Gambirasi, Arianna; Favaro, Monica; Patelli, AlessandroVoltolina, Stefano; Nodari, Luca; Aibéo, Cristina; Egel, Ellen; Pamplona, Marisa; Simon, Stefan; Falzacappa, Emanuele Verga; Scopece, Paolo; Gambirasi, Arianna; Favaro, Monica; Patelli, Alessandr

An Atmospheric Pressure Plasma Jet to Tune the Bioactive Peptide Coupling to Polycaprolactone Electrospun layers

The surface chemistry of scaffolds for tissue regeneration can guide cells growth. In this study, we present a novel method to functionalize electrospun Polycaprolactone (PCL) scaffolds allowing the tuning of biomolecule superficial concentration by varying only one process parameter. The method is based on the deposition of NH2 functional groups starting form (3-Aminopropyl) triethoxysilane (APTES) as precursor by a novel Atmospheric Pressure Plasma Jet (APPJ) and by a successive selective covalent linking of these amines with a synthetic Human Vitronectin adhesive cue (HVP). The addition, in the peptide C-terminus, of an aldehyde group ensures the selective ligation by alkylimino-de-oxo-bisubstitution between the primary amine and HVP. By this method, we managed to alter the HVP surface concentration just varying the deposition time of the plasma process; this resulted in different surface coverage of the plasma coating, which in turn led to diverse amount of linked HVP. Coating stability, morphology and coverage was assessed by infrared and photo-electron spectroscopies and by electron microscopy. As a function of the coverage a variation on peptide concentration was revealed by Total Nitrogen method and confirmed by biological assays, which demonstrated an increase of human osteoblasts viability as a function of peptide concentration