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Nanostructured metal oxide semiconductors (MOS) are considered proper candidates to develop low cost and real-time resistive sensors able to detect volatile organic compounds (VOCs), e.g., diacetyl. Small quantities of diacetyl are generally produced during the fermentation and storage of many foods and beverages, conferring a typically butter-like aroma. Since high diacetyl concentrations are undesired, its monitoring is fundamental to identify and characterize the quality of products. In this work, a tin oxide sensor (SnO2) is used to detect gaseous diacetyl. The effect of different working atmospheres (air, N2 and CO2), as well as the contemporary presence of ethanol vapors, used to reproduce the typical alcoholic fermentation environment, are evaluated. SnO2 sensor is able to detect diacetyl in all the analyzed conditions, even when an anaerobic environment is considered, showing a detection limit lower than 0.01 mg/L and response/recovery times constantly less than 50 s.

This study is focused on the compositional and structural analysis of marine sediments from eight different sites of the Calabria region, south of Italy. For this purpose, a combination of spectroscopic techniques is utilised. X-ray fluorescence spectrometry is used for the quantitative elemental analysis of the investigated samples. To identify their crystalline mineral components and study their microstructure, X-ray diffraction and Raman scattering measurements are carried out. SiO2 and Al2O3 are the most abundant sediment components. Fe2O3, K2O, Na2O, MgO and CaO are also present in smaller amounts as well as TiO2 and P2O5. Sediments are characterised by a narrow range of Al2O3/SiO2 abundance ratio and a wider range of the overall Fe2O3 + MgO concentration. The analysis of the geochemical discriminating factors indicates that the marine sediments under study come from the dismantling and transportation of materials of the “Calabrian–Peloritan arc”, whose rocks are acidic intrusive igneous and metamorphic. From the environmental point of view, the obtained results can be used to assess changes in the pollution level due to geological processes.

An experimental research has been done investigating the effects of the addition of multi-walled Carbon Nanotubes (CNTs) on the rheological behaviour of bitumen and its microstructure. two different types of CNT have been tested, consisted of a product obtained by laboratory synthesis through Catalytic Chemical Vapour Deposition (CCVD) technique and a commercial one, hereinafter are called type 1 and type 2, respectively. Both types of CNTs were completely characterized in terms of morphological, chemical, and structural properties. In addition, the rheological analysis were also conducted on bitumen blends containing CNT providing a complete study understanding the effectiveness of introduced CNT compared to those of commercial ones as for bitumen modification. For this purpose the experimental plan consisted of Trasmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), micro-Raman spectroscopy, and rheological analysis in oscillatory regime.

The knowledge of material physical properties is essential for a proper design of micro-electronic or micro-photonic devices. In this work, the thermo-optic effect, namely the refractive index dependence on temperature, was analized for 4H silicon carbide (4H-SiC) at the wavelength of interest for fiber-optic communication systems, $A$ = 1.55 µm, by using a simple direct technique based on the multiple beam interference in a Fabry-Perot cavity. Measurements of refractive index and extinction coefficient were carried out in a wide wavelength range by spectroscopic ellipsometry.

The presence of heavy minerals, including radionuclides such as 238U and 232Th, in the beach placers outcropping along the western Calabrian coast (South Italy) has been investigated in order to single out the contribution from natural sources to the total radiation level. Assessing the human health radiation risk for these areas is of great importance due to their main touristic destination. With the aim of characterizing the natural radionuclides contents of the Calabrian sands, the correlations existing between their mineralogical and geochemical features and those of the parent rocks have been studied by measuring the sand radionuclides concentrations and decay products and by calculating the outdoor effective dose rate. The radioactivity in the Calabrian beach sediments is for the most part attributed to monazite and, in turn, to the high amount of Th (in the 409–464 ppm range), and is a function of the rock types and of the formation processes. The outdoor dose and effective dose rates for an exposure period of three months are in the range 1045–1240 nGy/h and 0.32–0.37 mSv/y, respectively. Although these values are remarkably higher than the corresponding average world values, they fall within the limits fixed by the Italian legislation, assuming individuals that spend three summer months on the beach. The results obtained for this area of the Southern Italy coastlines can be used as a baseline for future investigations concerning radioactivity background levels, also in other regions. Moreover, the coupling of the present findings with those of epidemiological studies will allow gaining a better evaluation of possible health effects on the population.

Low-dimensional carbon materials occupy a relevant role in the field of nanotechnology. Herein, the authors report a study conducted by atomic force microscopy and Raman spectroscopy on the deposition of carbon dots onto graphene surfaces. The study aims at understanding if and how the morphology and the microstructure of chemical vapor deposited graphene on Si/SiO2 may change due to the interaction with the carbon dots. Potential alteration in the graphene's electrical properties might be detrimental for optoelectronic applications. The deposition of carbon dots dispersed in water and ethanol solvents are explored to investigate the effect of solvents with different fluidic properties. The obtained results indicate that the carbon dots do not alter the quality of graphene.

Schottky-barrier solar cells (SBSCs) represent low-cost candidates for photovoltaics applications. The engineering of the interface between absorber and front electrode is crucial for reducing the dark current, blocking the majority carriers injected into the electrode, and reducing surface recombination. The presence of tailored interfacial layers between the metal electrode and the semiconductor absorber can improve the cell performance. In this work, the interface of a graphene/n-type Si SBSC by introducing a graphene-based derivative (GBD) layer meant to reduce the Schottky-barrier height (SBH) and ease the charge collection are engineered. The chemical vapor deposition (CVD) parameters are tuned to obtain the two graphene films with different structure and electrical properties: few-layer graphene (FLG) working as transparent conductive electrode and GBD layer with electron-blocking and hole-transporting properties. Test SBSCs are fabricated to evaluate the effect of the introduction of GBD as interlayer into the FLG/n-Si junction. The GBD layer reduces the recombination at the interface between graphene and n-Si, and improves the external quantum efficiency (EQE) with optical bias from 50 to 60%. The FLG/GBD/n-Si cell attains a power conversion efficiency (PCE) of ≈5%, which increase to 6.7% after a doping treatment by nitric acid vapor.

High-quality graphene can be produced in large scale by chemical vapor deposition (CVD). Ethanol is emerging as a versatile carbon source alternative to methane for the growth of graphene on a copper (Cu) foil catalyst. To date, rigorous studies of the ethanol-based process still lack, especially concerning the first stages of the growth, which ultimately determines graphene's properties, such as defect density and crystal size, and performance, such as electrical conductance and mechanical strength. In particular, so far the growth of isolated graphene grains by ethanol-CVD has been achieved only on preoxidized Cu foils folded in enclosures, in an attempt to limit the partial pressure of the precursor, and thus the nucleation rate. We systematically explored the process parameters of ethanol-CVD to obtain full control over the nucleation rate, grain size, and crystallinity of graphene on flat Cu foils, which are of interest for any realistic production in large scale. To limit the nucleation density and increase the grain size, preoxidized Cu foils (250 °C in air) were used as substrates, and the process parameters were thoroughly investigated and tuned. Ultimately, at an ethanol vapor flow of 1.5 × 10-3 sccm the nucleation density reduced to less than 3 nuclei/mm2 and isolated single-crystal grains grew with a lateral size above 500 μm. When transferred onto Si/SiO2 substrates, these grains showed field-effect mobility beyond 1300 cm2/(V s). Our results provide a step closer towards an affordable commercialization of electronic-grade, large-area graphene. © 2018 American Chemical Society.