Short Heat Treatments for the F357 Aluminum Alloy Processed by Laser Powder Bed Fusion

Conventionally processed precipitation hardening aluminum alloys are generally treated with T6 heat treatments which are time-consuming and generally optimized for conventionally processed microstructures. Alternatively, parts produced by laser powder bed fusion (L-PBF) are characterized by unique microstructures made of very fine and metastable phases. These peculiar features require specifically optimized heat treatments. This work evaluates the effects of a short T6 heat treatment on L-PBF AlSi7Mg samples. The samples underwent a solution step of 15 min at 540 °C followed by water quenching and subsequently by an artificial aging at 170 °C for 2-8 h. The heat treated samples were characterized from a microstructural and mechanical point of view and compared with both as-built and direct aging (DA) treated samples. The results show that a 15 min solution treatment at 540 °C allows the dissolution of the very fine phases obtained during the L-PBF process; the subsequent heat treatment at 170 °C for 6 h makes it possible to obtain slightly lower tensile properties compared to those of the standard T6. With respect to the DA samples, higher elongation was achieved. These results show that this heat treatment can be of great benefit for the industry

Fabrication of a Highly NO2-Sensitive Gas Sensor Based on a Defective ZnO Nanofilm and Using Electron Beam Lithography

Hazardous substances produced by anthropic activities threaten human health and the green environment. Gas sensors, especially those based on metal oxides, are widely used to monitor toxic gases with low cost and efficient performance. In this study, electron beam lithography with two-step exposure was used to minimize the geometries of the gas sensor hotplate to a submicron size in order to reduce the power consumption, reaching 100 °C with 0.09 W. The sensing capabilities of the ZnO nanofilm against NO2 were optimized by introducing an enrichment of oxygen vacancies through N2 calcination at 650 °C. The presence of oxygen vacancies was proven using EDX and XPS. It was found that oxygen vacancies did not significantly change the crystallographic structure of ZnO, but they significantly improved the electrical conductivity and sensing behaviors of ZnO film toward 5 ppm of dry air

Sub-ppm NO2 Detection through Chipless RFID Sensor Functionalized with Reduced SnO2

NO2 is an important environmental pollutant and is harmful to human health even at very low concentrations. In this paper, we propose a novel chipless RFID sensor able to work at room temperature and to detect sub-ppm concentration of NO2 in the environment. The sensor is made of a metallic resonator covered with NO2-sensitive tin oxide and works by monitoring both the frequency and the intensity of the output signal. The experimental measurements show a fast response (a few minutes) but a very slow recovery. The sensor could therefore be used for non-continuous threshold monitoring. However, we also demonstrated that the recovery can be strongly accelerated upon exposure to a UV source. This opens the way to the reuse of the sensor, which can be easily regenerated after prolonged exposure and recycled several times

PDMS-Based Microdevices for the Capture of MicroRNA Biomarkers

The isolation and analysis of circulating biomarkers, the main concern of liquid biopsy, could greatly benefit from microfluidics. Microfluidics has indeed the huge potentiality to bring liquid biopsy into the clinical practice. Here, two polydimethylsiloxane (PDMS)-based microdevices are presented as valid tools for capturing microRNAs biomarkers from clinically-relevant samples. After an extensive study of functionalized polydimethylsiloxane (PDMS) properties in adsorbing/eluting microRNAs, the best conditions were transferred to the microdevices, which were thoroughly characterized. The channels morphology and chemical composition were measured, and parameters for the automation of measures were setup. The best working conditions were then used with microdevices, which were proven to capture microRNAs on all channel surfaces. Finally, microfluidic devices were successfully validated via real-time PCR for the detection of a pool of microRNAs related to non-small cell lung cancer, selected as proof-of-principle. The microfluidic approach described here will allow a step forward towards the realization of an ecient microdevice, possibly automated and integrated into a microfluidic lab-on-a-chip with high analytical potentialities

Coazze near Gazzo Veronese, at the fringes of Veneto and Etruria Padana, NE Italy

The archaeological site of Coazze, near Gazzo Veronese (NE Italy) is located at the southwestern border of the Palaeovenetian territory, during the Final Bronze 3 and through the Iron Age. The systematic study of the finds resulting from almost 150 years of rescue and chance finds, planned excavations and surveys are allowing the proper definition of this proto-urban settlement, even if it has been hardly damaged by subsequent agrarian use. Its favourable geomorphological location, directly on the important riverine routes of the Tartaro and Adria Po Rivers, contributed to its relevant connective history, with testimonies of long-lasting contacts from the Alpine area to the Mediterranean, through deltaic emporia, such as Frattesina, San Basilio, and Adria. The relationship with the Etruscan sites founded in the Mincio Valley since the late 6th century BC, like Forcello, is particularly complex. Immediately before this period, between the end of 7th and early 6th century BC, there are clear signs at Coazze of the presence of a multiethnic community, in an expanding phase of the site, extending at least 61 ha. It is proposed that Coazze was then the crucial settlement of a polity that extended north-south along the resurgence rivers Tione and Tartaro. The asymmetric position of Coazze inside the polity is coherent with its role as a gateway community (sensu Hirth 1978). A crisis for the settlement is thought to have started in the 4th century BC, approximately at the time of the Forcello abandonment; the lowland area of Le Basse was in use during this phase, and the site continued to be involved in relevant trade and craft activities. The presence of Celtic materials in the 3rd to 2nd century BC is somehow still elusive. Coazze is an important case of a minor, but apparently independent town in the Palaeovenetian settlement network, with a peculiar history of interaction and connectedness

Design of a Nanostructured Metal-Oxide Solid Solution for Gas Sensing Applications

Recently, great attention has been paid to nanostructures solid solutions based on metal oxides to enhance sensing performance with respect to those of single-oxide counterparts. Tin and titanium dioxides (SnO2 and TiO2) are wide-gap n-type semiconductors extensively investigated for the fabrication of solid-state devices for gas sensing applications. They would easily form solid solutions since they can exhibit a rutile type structure where octahedrally coordinated Ti4+ and Sn4+ have similar ionic radii. Such solid solution combines the positive qualities of the singles oxides, e.g. high sensitivity towards reducing gases and low influence by humidity [1,2]. Despite the good sensing performances of Sn1-xTixO2, a further improvement has been attempted by means of an Nb doping. The incorporation of Nb5+ would increase the conductivity of the material, as niobium acts as donor dopant in n-type semiconductors, and inhibit grain growth [3]. (Sn,Ti,Nb)xO2 powders were synthetized through co-precipitation by keeping the Sn/Ti proportion constant at the optimal value for sensing performance, while changing Nb concentrations and calcination temperature. Powder compositions, structures and morphologies were investigated by different techniques. Observations at SEM microscopy revealed that the morphology consists of rounded nanoparticles (Fig.1) and X-ray powder diffraction analyses confirm that (Sn,Ti,Nb)xO2 samples were a rutile-type solid solution of tin, titanium and niobium. Electrical characterization of the films showed that the niobium concentration and the heating treatment of powders are fundamental parameters to optimise the sensing characteristics of the chemiresistive film in terms of sensibility (Fig.2) and selectivity. [1] C. Malagù, V. Guidi, M.C. Carotta, G. Martinelli, Appl. Phys. Lett. 84, (2004) 4158 [2] M.C. Carotta, et al., Sensors and Actuators B 139 (2009) 329–339 [3] Ferroni, M., et al. Sensors and Actuators B: Chemical 68.1-3 (2000) 140-14

Nanostructured SmFeO3 Gas Sensors: Investigation of the Gas Sensing Performance Reproducibility for Colorectal Cancer Screening

Among the various chemoresistive gas sensing properties studied so far, the sensing response reproducibility, i.e., the capability to reproduce a device with the same sensing performance, has been poorly investigated. However, the reproducibility of the gas sensing performance is of fundamental importance for the employment of these devices in on-field applications, and to demonstrate the reliability of the process development. This sensor property became crucial for the preparation of medical diagnostic tools, in which the use of specific chemoresistive gas sensors along with a dedicated algorithm can be used for screening diseases. In this work, the reproducibility of SmFeO3 perovskite-based gas sensors has been investigated. A set of four SmFeO3 devices, obtained from the same screen-printing deposition, have been tested in laboratory with both controlled concentrations of CO and biological fecal samples. The fecal samples tested were employed in the clinical validation protocol of a prototype for non-invasive colorectal cancer prescreening. Sensors showed a high reproducibility degree, with an error lower than 2% of the response value for the test with CO and lower than 6% for fecal samples. Finally, the reproducibility of the SmFeO3 sensor response and recovery times for fecal samples was also evaluated

PDMS-Based Microdevices for the Capture of MicroRNA Biomarkers

none9The isolation and analysis of circulating biomarkers, the main concern of liquid biopsy, could greatly benefit from microfluidics. Microfluidics has indeed the huge potentiality to bring liquid biopsy into the clinical practice. Here, two polydimethylsiloxane (PDMS)-based microdevices are presented as valid tools for capturing microRNAs biomarkers from clinically-relevant samples. After an extensive study of functionalized polydimethylsiloxane (PDMS) properties in adsorbing/eluting microRNAs, the best conditions were transferred to the microdevices, which were thoroughly characterized. The channels morphology and chemical composition were measured, and parameters for the automation of measures were setup. The best working conditions were then used with microdevices, which were proven to capture microRNAs on all channel surfaces. Finally, microfluidic devices were successfully validated via real-time PCR for the detection of a pool of microRNAs related to non-small cell lung cancer, selected as proof-of-principle. The microfluidic approach described here will allow a step forward towards the realization of an efficient microdevice, possibly automated and integrated into a microfluidic lab-on-a-chip with high analytical potentialities.noneLunelli, Lorenzo; Barbaresco, Federica; Scordo, Giorgio; Potrich, Cristina; Vanzetti, Lia; Marasso, Simone Luigi; Cocuzza, Matteo; Pirri, Candido Fabrizio; Pederzolli, CeciliaLunelli, Lorenzo; Barbaresco, Federica; Scordo, Giorgio; Potrich, Cristina; Vanzetti, Lia; Marasso, Simone Luigi; Cocuzza, Matteo; Pirri, Candido Fabrizio; Pederzolli, Cecili

Design of a Metal-Oxide Solid Solution for Sub-ppm H2 Detection

: Hydrogen is largely adopted in industrial processes and is one of the leading options for storing renewable energy. Due to its high explosivity, detection of H2 has become essential for safety in industries, storage, and transportation. This work aims to design a sensing film for high-sensitivity H2 detection. Chemoresistive gas sensors have extensively been studied for H2 monitoring due to their good sensitivity and low cost. However, further research and development are still needed for a reliable H2 detection at sub-ppm concentrations. Metal-oxide solid solutions represent a valuable approach for tuning the sensing properties by modifying their composition, morphology, and structure. The work started from a solid solution of Sn and Ti oxides, which is known to exhibit high sensitivity toward H2. Such a solid solution was empowered by the addition of Nb, which─according to earlier studies on titania films─was expected to inhibit grain growth at high temperatures, to reduce the film resistance and to impact the sensor selectivity and sensitivity. Powders were synthesized through the sol-gel technique by keeping the Sn-Ti ratio constant at the optimal value for H2 detection with different Nb concentrations (1.5-5 atom %). Such solid solutions were thermally treated at 650 and 850 °C. The sensor based on the solid solution calcined at 650 °C and with the lowest content of Nb exhibited an extremely high sensitivity toward H2, paving the way for H2 ppb detection. For comparison, the response to 50 ppm of H2 was increased 6 times vs SnO2 and twice that of (Sn,Ti)xO2

Solid phase DNA extraction on PDMS and direct amplification

none10Laura Pasquardini; Cristina Potrich; Marzia Quaglio; Andrea Lamberti; Salvatore Guastella; Lorenzo Lunelli; Matteo Cocuzza; Lia Vanzetti; Candido Fabrizio Pirri; Cecilia PederzolliPasquardini, Laura; Potrich, Cristina; Marzia, Quaglio; Andrea, Lamberti; Salvatore, Guastella; Lunelli, Lorenzo; Matteo, Cocuzza; Vanzetti, Lia Emanuela; Candido Fabrizio, Pirri; Pederzolli, Cecili