Surface Pretreatments of Silicon Nitride for CVD Diamond Deposition

The efficiency of different surface pretreatments (four standard chemical etchings and four diamond powder abrasive procedures) on silicon nitride (Si₃N₄) substrates for chemical vapor deposition (CVD) of diamond has been systematically investigated. Blank Si₃N₄ samples were polished with colloidal silica (∼0.25 μm). Diamond nucleation and growth runs were conducted in a microwave plasma chemical vapor deposition apparatus for 10 min and 6 h, respectively. Superior results concerning nucleation density ( N _d∼ 10¹⁰ cm⁻² after 10 min), film uniformity, and grain size (below 2 μm after 6 h) were obtained for the mechanically microflawed samples, revealing that chemical etchings (hot and cold strong acids, molten base or CF₄ plasma) are not crucial for good CVD diamond quality on Si₃N₄.     

NbO/Nb2O5 core–shells by thermal oxidation

Niobium oxides have been reported as an alternative to tantalum, and its oxide, for the production of capacitors, but these materials still require a further and exhaustive study. Understanding the dynamics of the oxidation process from NbO to Nb₂O₅ is essential to explain and control the properties of a niobium oxide based capacitors. In situ XRD analysis of NbO powders was performed from 100 to 1100 °C, which showed a temperature range where only amorphous phase is present. The capacitor anodes, formed from the same type of NbO powders, were then heat-treated in air from room-temperature (RT) to 550 °C and recorded with a video camera to see the colour shift. The presence of core–shell structures and the increase of the shell thickness/amount with temperature are visible in SEM. Finally, in situ spectroscopy studies were performed, in order to observe the interference spectra which are responsible for the observed colours.     

Evaluation of gamma rays influence on some biochemical and microbiological aspects in black truffles

The effects of two gamma-ray doses (1.5 kGy and 2.0 kGy) on some biochemical aspects and on the microbiological profile of black truffles was monitored, immediately after treatment and after 30 days of storage at 4 °C. Electrophoretic and chromatographic analyses of proteins and peptides, just like monitoring of polyphenol content, peroxides formation and microbial profile, allowed for the first time a better understanding of the mechanisms responsible for biochemical alterations and bacterial pattern in black truffles during their storage. Treatment at 1.5 kGy appeared to better preserve the characteristics of the fresh product. In 2.0 kGy-samples, the protein profile was characterised by a 20 kDa-polypeptide, which could be considered as an useful marker of the irradiation treatment and of the storage time of the product. MALDI-TOF mass spectrometry analysis did not permit a correct identification from tryptic peptides in databases, although the nano-ES/MS/MS analyses performed on the 10 kDa tryptic digest peptides showed an amino acidic sequence entirely contained in a protein of filamentous fungus Neurospora crassa.     

Determination of Lutein from Fruit and Vegetables Through an Alkaline Hydrolysis Extraction Method and HPLC Analysis

A simple and rapid analytical method for the determination of lutein content, successfully used for cereal matrices, was evaluated in fruit and vegetables. The method involved the determination of lutein after an alkaline hydrolysis of the sample matrix, followed by extraction with solvents and analysis by normal phase HPLC. The optimized method was simple, precise, and accurate and it was characterized by few steps that could prevent loss of lutein and its degradation. The optimized method was used to evaluate the lutein amounts in several fruit and vegetables. Rich sources of lutein were confirmed to be green vegetables such as parsley, spinach, chicory, chard, broccoli, courgette, and peas, even if in a range of variability. Taking into account the suggested reference values these vegetables can be stated as good sources of lutein.     

Periodic input flows tuning nonlinear two-phase dynamics in a snake microchannel

In this experimental study, the effects on two-phase flow dynamics in a microfluidic snake channel due to periodic forcing were considered. Time series analysis was exploited to investigate on the obtained bubbles’ flow considering two aspects: the role of driven frequency through Fourier analysis and the nonlinear behavior through the evaluation of d-infinite and Largest Lyapunov exponent. Phase diagrams summarize the results: the two nonlinear parameters are plotted versus the air fraction and the frequency of the input flow rates. The identified relation maps allow the classification of the flow dynamics, opening the way for the control of bubble flow through signal analysis.     

Influence of microorganisms on retinol isomerization in milk

In order to have a deeper insight into the retinol isomerization phenomenon, in this work different milk samples have been analysed for their content of trans retinol and its cis-isomers, by means of reliable HPLC techniques. Levels of the different isomers and the degree of retinol isomerization (13-cis/all-trans ratio, %) have been monitored during milk storage at different temperatures and after addition of specific microorganisms. In raw milk stored at 4 degrees C for 96 h the degree of retinol isomerization shifted from 1.1 to 2.3%, while in raw milk stored at 22 degrees C for 24 h it increased from 1.1 to 12.7%. Among microorganisms tested in pasteurized milk, the most active in causing an increment in the 13-cis/all-trans ratio (%), from 3.4 to 33.4% in 8 h, was Streptococcus thermophilus. The results obtained demonstrated a relationship between microbial evolution and retinol isomerization. Therefore, the determination of retinol isomers is of importance not only for a more precise evaluation of vitamin A activity but also for the evaluation of the microbiological quality of milk.     

Extraction of wheat germ oil by supercritical CO<Subscript>2</Subscript>: Oil and defatted cake characterization

In this paper the working conditions for the extraction of wheat germ oil in a supercritical CO₂ pilot plant of 1-L-extraction capacity were studied. The best conditions were: pressure, 38 MPa; temperature, 55°C; wheat germ particle size, about 0.35 mm; CO₂ flow rate, 1.5 L min⁻¹. These conditions gave yields of about 92% of total oil after 3 h of processing. The obtained oils and the partially defatted cake were investigated with regard to their FA, tocol (tocopherol and tocotrienol), carotenoid, and sterol compositions and to their quality characteristics (FFA, PV, para-anisidine value, and color of the by product). Moreover, the oil quality was evaluated in relation to the progress of the supercritical extraction.     

Innovative Caciocavallo cheeses made from a mixture of cow milk with ewe or goat milk

This study assessed and compared the physicochemical, microbiological, and sensorial characteristics of Caciocavallo cheeses, made from cow milk and a mixture of cow with ewe or goat milk, during ripening. Different cheese-making trials were carried out on an industrial scale following the standard procedure of pasta filata cheeses, with some modifications. The percentage of the different added milk to cow milk influenced compositional and nutritional characteristics of the innovative products, leading to a satisfactory microbiological and sensorial quality.     

Anisotropy and symmetry in porous media convection

The linear and nonlinear stability analysis of the motionless state (conduction solution) and of a vertical throughflow in an anisotropic porous medium is performed. In particular, the effect of a nonhomogeneous porosity and a constant anisotropic thermal diffusivity have been taken into account.