Lactic acid bacteria biodiversity in Italian marinated seafood salad and their interactions on the growth of Listeria monocytogenes

The aim of this research was to study the biodiversity of lactic acid bacteria (LAB) in marinated seafood salad (pH 5.0) and their interaction on the growth of Listeria monocytogenes. LAB were highly present in the samples considered in this study, reaching values of 8.0 log cfu/g at the end of product’s shelf-life. A high biodiversity in terms of LAB species and strains was detected by means of RAPD–PCR within the 171 bacterial isolates collected. Among them Lactobacillus curvatus, Lactobacillus sanfranciscensis and Enterococcus were present in all the salad batches considered. Three challenge tests against L. monocytogenes were carried out in order to assess the growth of this pathogen in the presence of dominant populations of LAB. L. monocytogenes tended to decrease in time, suggesting that a stable concentration of LAB inhibits the development of this pathogenic micro-organism.     

Shell-and-Tube Minichannel Condenser for Low Refrigerant Charge

The design of an innovative shell-and-tube heat pump condenser using 2 mm ID minichannels is presented. This condenser has been designed aiming at the minimization of the charge, which can be required by safety or environmental restrictions. Nevertheless, minichannels represent also a solution to the high-pressure challenge when using carbon dioxide as a refrigerant. The present prototype was realized for the use with propane in the framework of the European project SHERHPA, concerning the development of heat pumps working with natural fluids. Experimental data for heat transfer and pressure drop are reported in the present paper. The measurements have been obtained using refrigerant R22, which displays a temperature versus pressure saturation curve pretty close to the one of propane. The data have also been compared against a computational procedure for shell-and-tube heat exchangers design. The refrigerant charge has been computed by means of different void fraction correlations, showing that the expected charge is less than half the quantity required by a brazed plate condenser giving the same capacity.     

Phenotypic and genotypic characterization of Oenococcus oeni strains isolated from Italian wines

A phenotypic and genotypic characterization of 84 Oenococcus oeni isolates from Italian wines of different oenological areas was carried out. Numerical analysis of fatty acid profiles grouped the isolates into two clusters at low level of similarity (63%), the minor cluster containing seven isolates besides the type and the reference strains. Forthy-eight O. oeni isolates, representative of the two clusters, showed no differences in their metabolic properties (heterolactic fermentation pattern, citrate degradation capability and formation of some secondary metabolites). Moreover, the analysis of species-specific randomly amplified polymorphic DNA and 16S-23S rDNA intergenic spacer region polymorphism as well as the sequence-specific separation of V3 region from 16S rDNA by denaturing gradient gel electrophoresis demonstrated a substantial homogeneity among the isolates. On the basis of ApaI Pulsed Field Gel Electrophoresis (PFGE) restriction patterns, the 84 isolates were grouped into five different clusters at 70% similarity, but no correlation with the phenotypic groups could be demonstrated. However, by combining phenotypic and genotypic data, the 84 O. oeni isolates grouped into eight phenotypic-genotypic combined profiles and a relationship between the origin of the isolates and their combined profile became evident, so that a sort of strain specificity can be envisaged for each wine-producing area.     

Continuous production of wine vinegar in bubble column reactors of up to 60-litre capacity

This paper describes the development of a continuous acetic acid fermentation process for the production of wine vinegar in bubble column reactors of up to 60 l capacity. To determine appropriate fermentation conditions a study of the influence of residual ethanol concentration, inlet flow rate and aeration was carried out using a 6-l laboratory reactor, white table wine as fermentation medium, a temperature of 30 °C and an air flow rate of 0.125 min^-1 (vvm). The concentration of acetic acid obtained in the continuous wine vinegar production ranged from 91 g/l at 28.6 ml/h to 28 g/l at 154.1 ml/h by increasing the inlet flow rate. As expected, the biomass decreased as well, from 208 mg/l to 106 mg/l. The maximum acetification rate was observed in the range 85-110 ml/h, corresponding to a value of about 1.1 g/l/h. A further increase in the flow rate produced a slight decrease in the acetification rate. Best yields, between 94.5 and 94.7%, were obtained in the flow rate range of 60-75 ml/h. The acetification rate was improved only by about 10% by increasing the aeration from 0.125 to 0.250 min^-1. The continuous wine vinegar production was scaled up from the laboratory fermentor to a 60-l pilot acetator. During the steady state (residential time >6), with an inlet flow rate of 950 ml/h, temperature of 30 °C and aeration of 0.250 min^-1, the following parameters were obtained: acetic acid concentration 72 g/l, overall productivity 1.41 g/l/h and yield 94.2%.     

A high precision temperature control system for CMOS integrated wide range resistive gas sensors

In this work we present an integrated interface for wide range resistive gas sensors able to heat the sensor resistance through a constant power heater block at 0°C–350°C operating temperatures. The proposed temperature control system is formed by a sensor heater (which fixes the sensor temperature at about 200°C), a R/f (or R/T) converter, which converts the resistive value into a period (or frequency), and can be able to reveal about 6 decades variation (from 10 KΩ up to 10 GΩ), and a digital subsystem that control the whole systems loop. This interface allows high sensibility and precision and performs good stability in temperature and power supply drift and low power characteristics so it can be used also in portable applications. Test measurements, performed on the fabricated chip, have shown an excellent agreement between theoretical expectations and simulation results. Giuseppe Ferri is an associate professor in Electronics at the Department of Electrical Engineering of L’ Aquila University, Ital. In 1993 he has been a visiting researcher at SGS-Thomson Milano, working in bipolar low-voltage op-amp design. In 1994-95 he has been visiting researcher at KU Leuven working in low-voltage CMOS design in the group of Prof. Sansen. His research activity is actually centred on the analog design of integrated circuits for portable applications (e.g., sensors and biomedicals) and circuit theory. He is co-author of a book entitled “Low Voltage, Low Power CMOS Current Conveyors”, Kluwer ed. (2003) and four text-books in Italian on Analogue Microelectronics (2005, 2006). Moreover, he is author and co-author of 74 papers on international and Italian journals and 123 talks at national and international conferences. Vincenzo Stornelli was born in Avezzano (AQ), Italy, on May 31, 1980. He received the Electronics Engineering degree (cum laude) in July 2004. In October 2004 he joined the Department of Electronic Engineering, University of L’Aquila, where he is actually involved with problems concerning project and design of integrated circuits for RF and sensor applications, CAD modelling, characterization, and design analysis of active microwave components, circuits, and subsystems. He regularly teaches courses of the European Computer patent and has regular collaborations with national corporations such as Thales Italia     

An efficient self-timed adder realized using conventional CMOS standard cells

Usually, efficient self-timed adders are realized using the dynamic differential cascode voltage switch logic. This allows the end-completion to be easily detected, but it makes circuit design and testing very complex, compelling the production of full-custom layouts and leading to a very long time before marketing. This paper presents a new 56-bit high-speed self-timed adder realized with conventional AMS 0.35 μm CMOS standard cells. The proposed circuit uses overlapped execution circuits, which exploit the initialization time that always elapses between two consecutive addition operations. Compared to several self-timed adders existing in the literature, the addition circuit proposed here shows brilliant advantages in terms of speed-performance, silicon area occupancy and power dissipation.     

An algorithm for the recognition of levels of congestion in road traffic problems

Detection and recognition of the level of congestion at an intersection is a very important problem and a valuable source of information in traffic management. Although it is just one of all the aspects that make up a traffic management system, it seems to be a crucial point for gathering information. In this paper, we present a technique based on a k-means clustering algorithm for classification, which has been already successfully used in a number of pattern recognition problems, namely: as an algorithm for face recognition problems and in a number of medical diagnosis problems and it compares very well with the state of the art techniques.     

Fast algorithms for nonparametric population modeling of large data sets

Population models are widely applied in biomedical data analysis since they characterize both the average and individual responses of a population of subjects. In the absence of a reliable mechanistic model, one can resort to the Bayesian nonparametric approach that models the individual curves as Gaussian processes. This paper develops an efficient computational scheme for estimating the average and individual curves from large data sets collected in standardized experiments, i.e. with a fixed sampling schedule. It is shown that the overall scheme exhibits a “client-server” architecture. The server is in charge of handling and processing the collective data base of past experiments. The clients ask the server for the information needed to reconstruct the individual curve in a single new experiment. This architecture allows the clients to take advantage of the overall data set without violating possible privacy and confidentiality constraints and with negligible computational effort.     

Fly ash addition in clayey materials to improve the quality of solid bricks

The technical quality of two compositionally different groups of solid bricks fired between 800 and 1000 °C was evaluated. Five weight percentage of fly ash was added to both groups and they were compared with similar bricks with no added fly ash.The textures of the bricks with fly ash were very similar to the textures of those without it, except that the samples with the additive contained spherical fly ash particles with diameters ranging from 0.1 to 10 μm. These particles led to a reduction in the density of the bricks and a substantial improvement in their durability, with less decay being caused by salt crystallization in the pores. This is because fly ash causes a reduction in the number of micropores, the pores that make porous materials most vulnerable to salt-induced decay. Use of this additive could have practical implications as a means of recycling and for achieving cost savings in brick production.     

δ-Tocomonoenol: A new vitamin E from kiwi (Actinidia chinensis) fruits

A new vitamin E, δ-tocomonoenol, has been isolated from Actinidia chinensis (kiwi) fruits. The new structure, 2,8-dimethyl-2-(4,8,12-trimethyltridec-11-enyl)chroman-6-ol, has been elucidated on the basis of EIMS, 1D, and 2D NMR spectral data. GC–MS analysis of peels and pulps of kiwi showed that the new compound, together with δ-tocopherol, is mainly present in the fruit peel, whilst α-tocopherol is present in a similar amount in both matrices. The compound was tested for its radical-scavenging and antioxidant capabilities, by measuring its ability to scavenge DPPH (2,2′-diphenyl-1-picrylhydrazyl radical) and anion superoxide radical, and inhibit the formation of methyl linoleate conjugated diene hydroperoxides and TBARS (thiobarbituric acid reactive species).