Statistical approaches for farm and parasitic risk profiling in geographical veterinary epidemiology

We address the problem of farm and parasitic risk profiling in the context of Veterinary Epidemiology. We take advantage of a cross-sectional study carried out in the Campania Region in order to study the spatial distribution of 16 parasites in 121 ovine farms. We propose a tri-level hierarchical Bayesian model, which account for multivariate spatially structured overdispersion, to obtain estimate of posterior classification probabilities, that is for each parasite and farm the probability to belong to the set of the null hypothesis. We explore four decision rules based on either posterior probabilities or posterior means and compare the results in terms of the number of false discoveries/non-discoveries or the rate of false discovery/non-discovery. Our approach proved useful for parasitological risk profiling and we show that decision rules can be easily handled.     

Evidence for Bulk Residual Stress Strengthening in Al2O3/SiC Nanocomposites

The fracture behavior of Al₂O₃/SiC nanocomposites has been studied as a function of the SiC volume fraction and compared to that of the pure Al₂O₃ matrix. A pronounced strengthening effect was only observed for materials with low SiC content (i.e., ≤10 vol%) although no evidence of concurrent toughening was found. Assessment of near-tip crack opening displacement (COD) could not experimentally substantiate significant occurrence of an elastic crack-bridging mechanism, in contrast with a recently proposed literature model. Quantitative fractography analysis indicated that transgranular crack propagation in Al₂O₃/SiC nanocomposites depends on the location of the SiC dispersoids within the matrix texture; the higher the fraction of transgranularly located dispersoids, the more transgranular the fracture mode. Experimental evidence of remarkably high residual stresses arising from thermal dilatation mismatch (upon cooling) between Al₂O₃ and SiC phases were obtained by fluorescence and Raman spectroscopy. A strengthening mechanism is invoked which merely arises from residual stress through strengthening of Al₂O₃ grain boundaries.     

Synthesis and Structures of Two Triorganotin(IV) Polymers R3Sn{O2CC6H4[N=C(H)}{C(CH3)CH(CH3)-3-OH]-p} n (R = Me and Ph) Containing a 4-[(2Z)-(3-Hydroxy-1-methyl-2-butenylidene)amino] benzoic Acid Framework

Two new polymeric triorganotin(IV) complexes R₃Sn{O₂CC₆H₄[N=C(H)}{C(CH₃)CH(CH₃)-3-OH]-p} _n ([Me₃Sn(LH)] _n : 1) and ([Ph₃Sn(LH)] _n : 2) containing a 4-[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)amino]benzoate (LH) framework were prepared. Both compounds have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, IR and ¹¹⁹Sn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of complexes 1 and 2 reveal that they exist as polymeric zig-zag chains in which the LH-bridged Sn-atoms adopt a trans-R₃SnO₂ trigonal bipyramidal configuration with R groups in the equatorial positions and the axial sites occupied by an oxygen atom from the carboxylate ligand and the alcoholic oxygen atom of the next carboxylate ligand in the chain. The carboxylate ligands coordinate in the zwitterionic form with the alcoholic proton moved to the nearby nitrogen atom.     

Halogen bonding based recognition processes: a world parallel to hydrogen bonding

Halogen bonding is the noncovalent interaction between halogen atoms (Lewis acids) and neutral or anionic Lewis bases. The main features of the interaction are given, and the close similarity with the hydrogen bonding will become apparent. Some heuristic principles are presented to develop a rational crystal engineering based on halogen bonding. The focus is on halogen-bonded supramolecular architectures given by halocarbons. The potential of the interaction is shown by useful applications in the field of synthetic chemistry, material science, and bioorganic chemistry.     

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