An evolution algorithm for noise modeling of HEMT’s down to cryogenic temperatures

The implementation of an Evolution Algorithm (EA) for the cryogenic noise modeling of microwave devices has been the object of the present work. Several approaches exist to treat the modeling issue as far as advanced microwave transistors are concerned. The aim of such procedures is mostly oriented to extract a linear equivalent circuit including noise performance that allows to reproduce the global device behavior in a small signal regime. In the present paper, the authors show how EA’s can be employed to solve the noise modeling problem according to a black-box approach. The application refers to the simulation of the Noise Parameters of High Electron Mobility Transistors (HEMT) in the 6-18 GHz frequency range and down to cryogenic temperatures (90K) compared with experimental data. The quality of results indicates that EA techniques represent a truly alternative way to determine the microwave noise performance of HEMT devices, thus furnishing a flexible tool to support CAD of high sensitivity – ultra high speed circuits.     

New non-woven polyurethane-based biomaterials for the cultivation of hepatocytes: expression of differentiated functions

A new non-woven polyetherurethane support suitable to host cultured hepatocytes has been developed. Prior to its use in bioreactors and artificial liver devices, the biocompatibility of this new material was investigated. The experiments have shown that the survival and functionality of hepatocytes entrapped in the non-woven polymer were longer than that of monolayer cultured hepatocytes, under serum-free culture conditions. Hepatic specific metabolic functions, namely, synthesis of urea and synthesis and secretion of plasma proteins, were well maintained by hepatocytes entrapped in non-woven polyetherurethane sheets. Cells also retained the expression of biotransformation activities of 7-ethoxycoumarin-O-deethylase as well as CYP2A1, CYP2B1 and CYP3A1. The results presented in this paper point to non-woven polyetherurethane sheets as a suitable biocompatible support for functional, three-dimensional hepatocyte cultures.     

From the Boltzmann equation to fluid mechanics on a manifold

We apply the Chapman-Enskog procedure to derive hydrodynamic equations on an arbitrary surface from the Boltzmann equation on the surface.     

Determination of Alcohol Ethoxylates derivatized with Naphthoyl Chloride,in Waste Water Treatment Plant Influent,Effluent and Sludge Samples by Liquid Chromatography Mass Spectrometry

A new analytical procedure for the determination of alcohol ethoxylates (AE) in environmental samples such as influents, effluents and sludge from waste water treatment plants (WWTPs) was developed. Although some work had been previously published on the detection of AE in water samples, this is the first paper that deals with AE in sludge. Alcohol ethoxylates were removed from water samples by sorption on polymeric discs followed by extraction with methanol. The methanol extracts were cleaned up with two alumina solid-phase extractions (SPE) at different conditions of solvent polarity, one before and the other after derivatization with naphthoyl chloride. A final polishing step was carried out on a Florisil SPE column. Liquid chromatography/mass spectrometry with electrospray ionization was used to quantify AE as naphthoyl derivatives. The detection limits for AE ethoxymers range from 0.07 to 0.005 μg/L in water samples. The method was applied to an Italian WWTP in order to follow the fate of AE during treatment, AE concentrations of 839 μg/L, 0.46 μg/L and 10.6 mg/kg were respectively found in the inlet, outlet and sludge samples. AE removals of each ethoxymer in the plant were in the range 99.6–100% and no difference was observed between high or low-mole ethoxymers and between AE with odd or even carbon chain lengths. An overall 99.7% removal was also determined on the mass balance of AE in the inlet, the outlet, and sludge of the plant.     

Effect of processing parameters on the mechanical properties of in situ compatibilized polybutylene terephthalate/acrylonitrile–butadiene–styrene blends

To evaluate mechanical properties of blends prepared by intermeshing corotating twin‐screw extrusion (ICTSE), it is usually necessary to injection mold specimens after the extrusion mixing process. At this study an alternative method is used to obtain testing specimens from ribbons extruded polybutylene terephthalate/acrylonitrile–butadiene–styrene blends, (PBT/ABS), compatibilized with methyl methacrylate–glycidyl methacrylate‐ethyl acrylate (MGE) by ICTSE, and then to correlate their mechanical properties with the processing parameters. Regarding to the extrusion process parameters, it has been noted that higher feed rates, lower screw speeds and narrower kneading blocks have reduced the ductile‐brittle transition temperature (DBTT) of the compatibilized PBT/ABS blends, thereby suggesting that the molecule integrity of blend polymeric components has been preserved and that a good dispersion of the ABS domains in the PBT matrix has been achieved. Injection molded PBT/ABS blends were obtained to compare to the extruded ribbons. The mechanical tests for both specimens have shown the same trends. The injection molded samples have presented poorer impact strength, tensile strain at break and tensile strength, when compared to the respective extruded samples. That behavior has been attributed to the high level of molecular orientation resulting from the injection molding process and mainly to PBT degradation during process. The PBT degradation could have increased its degree of crystallinity, which has been confirmed by DSC measurements. As result, the blend became more brittle, decreasing its Izod impact strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Study of tropaeolin degradation by iron--proposition of a reaction mechanism

The degradation of tropaeolin by iron was studied under oxidizing and inert atmospheres. The products were identified by various chromatographic and spectroscopic methods. Under inert atmosphere, the proposed model of mechanism is based on the adsorption of tropaeolin by the sulfonate function on the solid iron, followed by a reduction of the –N=N– bond with formation of 1-amino-2-naphthol and sulfanilic acid. These two intermediaries were reduced to 1,2-dihydroxynaphthalene and benzene with NH₄⁺ and HSO₃⁻ liberation. Under oxidizing atmosphere, besides the reductions of tropaeolin, water and ferric ions, the existence of a homogeneous degradation was found. This process was explained (on the basis of surface iron potential monitoring) by a stepwise reduction of oxygen giving hydrogen peroxide. The initial stages of the mechanism were similar to those under inert atmosphere, but the degradation of the 1,2-dihydroxynaphthalene continued giving 1,2-naphthalenedione, then various polar monocyclic compounds leading to three unidentified volatile final products.     

A melanocortin 1 receptor (MC1R) gene polymorphism is useful for authentication of Massese sheep dairy products

Massese is an Italian sheep breed, with black or grey coat colour, mainly reared in the Tuscany and Emilia Romagna regions. Recently, the emerging interests in this breed have resulted in the production of Pecorino cheese obtained with only Massese milk. In order to be profitable, this marketing link between Massese breed and its products should be defended against fraudsters who could include milk of other sheep breeds or cow milk in Massese labelled productions. To identify the genetic factors affecting coat colour in sheep, we have recently analysed the melanocortin 1 receptor (MC1R) gene and identified several single nucleotide polymorphisms (SNPs). In this work, as a first step to set up a DNA based protocol for authentication of Massese dairy products, we further investigated the presence and distribution of one of these SNPs (c.-31G>A) in 143 Massese sheep and in another 13 sheep breeds (for a total of 351 animals). The Massese breed was fixed for allele c.-31A, whereas in all other breeds allele c.-31 G was the most frequent or with frequency of 0?·50. At the same nucleotide position the cattle MC1R gene carries the G nucleotide. Using these data we developed a method to detect adulterating milk (from other sheep breeds or from cow) in Massese dairy products based on the analysis of the c.-31G>A SNP. We first tested the sensitivity of the protocol and then applied it to analyse DNA extracted from ricotta and Pecorino cheese obtained with only Massese milk or obtained with unrestricted sheep and cattle milk. To our knowledge, this system represents the first one that can be used for breed authentication of a sheep production and that, at the same time, can reveal frauds derived from the admixture of milk of an unreported species.     

Mixtures of whey protein microgels and soluble aggregates as building blocks to control rheology and structure of acid induced cold-set gels

Whey proteins (WP) today offer an extremely high potential for innovative development of functional and nutritious food products. Acid cold-set gels present an interesting approach of gelation at low temperature upon acidification of preformed whey protein (WP) aggregates. In the present work, we aimed to demonstrate how structure and rheological properties of acid gels can be controlled by combining two types of WP aggregates with different structural and chemical properties. Whey protein microgels (WPM) and soluble aggregates (WPSA) were generated upon heating WP isolate in specific pH conditions and temperature, leading to Z-average hydrodynamic diameters close to 270 nm for WPM and 100 nm for WPSA. Mixtures of WPM and WPSA were prepared at different weight ratios ranging from 100% WPM to 100% WPSA. The total protein concentration was set to 4 or 8%wt. Acidification was performed at 40 °C by addition of 1%wt glucono-δ-lactone (GDL). Gelation was followed using turbidimetry and small deformation rheology as function of pH. Microstructures of the gel were investigated at different length scales using various microscopy techniques (CLSM, SEM, AFM). When the WPM/WPSA ratio decreased, the pH of gelation and the gel strength increased because of the different structure and chemical reactivity of the two types of WP aggregates. The final pH had a strong impact on the structure of the gels. When final pH decreased below pH 4.3, a structure change was suggested by turbidimetry measurements. This resulted in a non self-supporting gel or in a decrease of gel strength. For pH above 4.3, self supporting gel were obtained. The rheological properties of the gel could therefore be modulated depending on the properties of the building blocks used (WPM versus WPSA). Interestingly, the gel microstructures observed for WPM/WPSA mixtures or WPM were comparable to those of acidified skimmed milk gels ranging from coarse structures with clumps of aggregates or to homogeneous fine networks (WPSA only) that have been described for WP gels obtained upon direct heating at various pH.     

The influence of local factors on the prediction of fumonisin contamination in maize

BACKGROUND: Contamination by mycotoxins is a major concern to the maize industry in north‐east Italy where maize grain is often spoiled by Fusarium spp. In this work, fumonisins, deoxynivalenol and zearalenone were determined and an artificial neural network (ANN) model suitable for predicting mycotoxin contamination of maize at harvest time was developed. RESULTS: The occurrence of deoxynivalenol and zearalenone was very limited, while fumonisins concentration ranged from 163 and to 3663 µg kg^?1 in 2007, and from 333 to 11473 µg kg^?1 in 2008. Statistical data analysis of factors affecting fumonisins concentration revealed that irrigation, chemical treatment against the European corn borer and harvest date significantly affected the level of contamination (P < 0.05), although the relevance of the factors was different in 2007 and 2008. The neural network approach showed a significant correlation between ascertained values and predictions based on agronomic data. CONCLUSION: This is the first time that an artificial neural network has been used to predict fumonisin accumulation in maize: the prediction has been shown to have the potential for the development of a new approach for the rapid cataloging of grain lots. Copyright © 2012 Society of Chemical Industry     

Effects of tillage and nitrogen fertilisation on triticale grain yield,chemical composition and nutritive value

BACKGROUND: Given the interest in the development of cultivation systems with low agronomic input and environmental impact, the aim of this study was to determine the influence of tillage system (conventional tillage (CT), two‐layer tillage (TT), surface tillage (ST) and minimum tillage (MT)) and nitrogen (N) fertilisation rate (0, 50 and 100 kg ha^?1) on triticale grain and protein yields, chemical composition and nutritive value. RESULTS: There were no significant differences among tillage treatments in grain and protein yields. ST resulted in significantly higher crude protein (CP) and true soluble protein (TSP) contents as well as in vitro crude protein digestibility (CPD). Neutral detergent fibre concentration was significantly higher with ST than with MT, and this led to a small reduction (2 g kg^?1 dry matter (DM)) in in vitro true DM digestibility (IVTDMD). N fertilisation significantly increased grain and protein yields as well as CP, non‐protein nitrogen and TSP contents and CPD. IVTDMD was significantly lower with 0 kg N ha^?1 than with 50 and 100 kg N ha^?1. CONCLUSION: Reducing tillage intensity improved the CP content and CPD of triticale grain. The application of 50 kg N ha^?1 resulted in good grain quality parameters and grain and protein yields. Copyright © 2010 Society of Chemical Industry