DRYING OF WOOD CHIPS WITH AMBIENT AIR

This paper discusses the slow drying of wood chips stacked in deep beds by a flow of ambient air throughout the major part of the year. This kind of drying operation introduces some simplifications to the equation system. The celerity of the drying front is described by an analytical term, then the shape of the front is obtained by an ordinary differential equation. The meteorological data which has been put into the computer determines the progress of the drying front. The flow rate of the blower is determined from the operation characteristics (time allowed, height of the pile, moisture of the product, regulation function) and from the data of the local climate. An additional rudimentary solar collector can improve the efficiency of the system. A period of ten days will be sufficient to calculate the mean data in order to ascertain the progress of the front.     

Kinetics of the electrochemical deposition and dissolution of sodium tungsten bronzes

The electrochemical deposition of sodium tungsten bronzes from Na₂WO₄/WO₃ melts at 700–800°C has been studied. The kinetics of the deposition and the dissolution reactions have been investigated using galvanostatic step, open-circuit decay of electrode potential, and faradaic impedance measurements. The results show that the kinetics of electrochemical deposition are controlled by at least 3 processes: a heterogeneous reaction (surface diffusion of adion), a charge-transfer reaction, and some diffusion in the electrolyte. The relative role of diffusion in the electrolyte seems more important in the dissoluton process than in the deposition reaction.     

Use of global sensitivity analysis in quantitative microbial risk assessment: application to the evaluation of a biological time temperature integrator as a quality and safety indicator for cold smoked salmon

The aim of this study was to apply a global sensitivity analysis (SA) method in model simplification and to evaluate (eO)^®, a biological Time Temperature Integrator (TTI) as a quality and safety indicator for cold smoked salmon (CSS). Models were thus developed to predict the evolutions of Listeria monocytogenes and the indigenous food flora in CSS and to predict TTIs endpoint. A global SA was then applied on the three models to identify the less important factors and simplify the models accordingly. Results showed that the subset of the most important factors of the three models was mainly composed of the durations and temperatures of two chill chain links, out of the control of the manufacturers: the domestic refrigerator and the retail/cabinet links. Then, the simplified versions of the three models were run with 10⁴ time temperature profiles representing the variability associated to the microbial behavior, to the TTIs evolution and to the French chill chain characteristics. The results were used to assess the distributions of the microbial contaminations obtained at the TTI endpoint and at the end of the simulated profiles and proved that, in the case of poor storage conditions, the TTI use could reduce the number of unacceptable foods by 50%.     

Manageable risk factors associated with the lactational incidence, elimination, and prevalence of Staphylococcus aureus intramammary infections in dairy cows

Staphylococcus aureus intramammary infections (IMI) are a major cause of mastitis on farms worldwide. Incidence and elimination rates are the key determinants of prevalence of Staph. aureus, and risk factors associated with these rates must be identified, prioritized, and controlled to obtain long-term reduction in prevalence. The objectives of this study were to identify manageable risk factors associated with the lactational incidence, elimination, and prevalence of Staph. aureus IMI. A cohort of 90 Canadian dairy farms was recruited and followed in 2007 and 2008. Quarter milk samples were collected repeatedly from a selection of cows, and bacteriological culture was realized to assess incidence, elimination, and prevalence of Staph. aureus IMI. Practices used on farms were measured using direct observations and a validated questionnaire. A linear regression model was used to explore the relationship between herd IMI prevalence and incidence and elimination rates. Multilevel logistic regression models were used to compute measures of associations between practices used on farms and IMI incidence, elimination, and prevalence. The herd incidence rate was the most important predictor of herd IMI prevalence: a reduction of the incidence rate equivalent to its interquartile range (0.011 new IMI/quarter-month) was associated with a prevalence reduction of 2.2 percentage points; in comparison, an equivalent increase of the elimination rate by its interquartile range (0.36 eliminated IMI/quarter-month) resulted in a prevalence reduction of 0.4 percentage points. Postmilking teat disinfection and blanket dry-cow therapy were already implemented by most herds. Most of the practices associated with Staph. aureus IMI incidence were related to milking procedures. Among these, wearing gloves during milking showed desirable associations with IMI incidence, elimination, and prevalence. Similarly, adequate teat-end condition and use of premilking teat disinfection were associated with lower IMI incidence and prevalence. The initial herd prevalence of Staph. aureus IMI was positively associated with subsequent IMI incidence. This indicates that, in some situations, an initial reduction of the pool of infected quarters could be justified. Some housing practices were associated with IMI incidence, elimination, or prevalence. The effects of these latter practices, however, were often influenced by specific cow characteristics such as parity or days in milk. These results highlight the importance of good milking practices to prevent Staph. aureus IMI acquisition and, therefore, reduce their prevalence.     

Quantitative dietary exposure assessment of the Catalonian population (Spain) to the mycotoxin deoxynivalenol

The mycotoxin deoxynivalenol (DON) is one of the most common contaminants of cereals worldwide, and its occurrence has been widely reported in raw foods and foodstuffs, around the European region, including Catalonia. In the present work, a stochastic methodology has been applied to accurately assess the exposure of the Catalonian population (Spain) to DON through food consumption. Raw contamination data was provided by a large survey conducted in this region, in addition to the raw consumption data from a nutritional study specifically designed to assess the dietary intake of the main foodstuffs related to DON contamination for all population age groups. Contamination and consumption data were combined by simulation using an essentially parametric (P-P) method. The P-P method draws sampling values from distribution functions fitted to consumption and contamination data sets. Moreover, to quantify the accuracy and reliability of the statistics estimates, we built the related confidence intervals using a pseudo-parametric bootstrap method. Considering the results drawn from the P-P simulation method, the Catalonian population should be expected to be exposed at moderated levels of deoxynivalenol, the infants and individuals with ethnic dietary patterns being the most exposed population groups.     

A bacterial gene homologous to ABC transporters protect Oenococcus oeni from ethanol and other stress factors in wine

The wine lactic acid bacteria Oenococcus oeni has to cope with harsh environmental conditions including an acidic pH, a high alcoholic content, non-optimal growth temperatures, and growth inhibitory compounds such as fatty acids, phenolic acids and tannins. We here describe characterisation and cloning of the O. oeni omrA gene encoding a protein belonging to the ATP-binding cassette superfamily of transporters. The OmrA protein displays the highest sequence similarity with the subfamily of ATP-dependent multidrug resistance (MDR) proteins, most notably the bacterial Lactococcus lactis LmrA homologue of the human MDR1 P-glycoprotein. The omrA gene proved to be a stress-responsive gene since its expression was increased at high temperature or under osmotic shock. The OmrA protein function was tested in Escherichia coli, and consistent with the omrA gene expression pattern, OmrA conferred protection to bacteria grown on a high salt medium. OmrA also triggered bacterial resistance to sodium laurate, wine and ethanol toxicity. The homologous LmrA protein featured the same stress-protective pattern than OmrA when expressed in E. coli, and the contribution to resistance of both OmrA and LmrA transporters was decreased by verapamil, a well-known inhibitor of the human MDR1 protein. Genes homologous to omrA were detected in other wine lactic acid bacteria, suggesting that this type of genes might constitute a well-conserved stress-protective molecular device.     

Recurrent recovery of Pseudomonas oryzihabitans strains in a karstified chalk aquifer

Pseudomonas oryzihabitans is an uncommon pathogen that may cause catheter-associated infections, particularly in immunocompromised patients. Although it has been isolated from environment, the source of human infection is not well documented. In the present study, 14 isolates of P. oryzihabitans were recovered over a 28-month period from a karstified chalk aquifer, allowing to advance that distributed natural water could be a source of contamination. Microbiological analyses showed that the bacterium was mainly associated with suspended particulate matters. To investigate the clonality of P. oryzihabitans environmental isolates, 16S rRNA gene sequencing, antibiogram and randomly amplified polymorphic DNA (RAPD) typings were performed. Results demonstrated (i) the presence of at least three clones within the aquifer and (ii) that the presence of the bacterium in groundwater is not only the result of a biofilm bloom but also of an exogenous contamination.     

New green coatings made from fatty acid dispersions: improvement in barrier properties of biodegradable thermoplasticized-starch substrate

This work was aimed at developing new coatings on biodegradable substrates for possible use in food packaging. In order to study barrier properties of these coatings made from fatty acid dispersions, oxygen permeability, water vapor permeability and also contact angle measurements were carried out. The coatings made from a fatty acid exhibited good barrier properties towards oxygen gas. Moreover, these coatings presented a higher contact angle value than the one obtained directly for the substrate without coating; this can be likely due to the hydrophobic nature of fatty acid and the recrystallization of fatty acid during the drying process.     

Some computational and algorithmic developments in computational mechanics of discontinua

Discontinua simulations are becoming an important part of computational mechanics to the extent that computational mechanics of discontinua is becoming a separate sub-discipline of computational mechanics. Among the most widely used methods of computational mechanics of discontinua are discrete-element methods, combined finite-discrete-element methods and discontinuum deformation analysis methods. A range of key algorithmic procedures is common to most of these methods. These include contact detection, explicit solvers, fracture and fragmentation models, handling of complex geometric considerations when processing interaction in three dimensions (contact kinematics) and fluid coupling. In recent years, there have been major breakthroughs in almost all of these key algorithmic aspects. These include linear contact-detection procedures (NBS, C-grid), discretized contact solutions, fracture and fragmentation solutions, together with fluid pressure driven fracture process and three-dimensional explicit solvers incorporating finite rotations. Many of these breakthroughs have not yet been applied across the full range of relevant discontinuum problems. The major reason for this is that discrete-element method, discontinuum deformation analysis and combined finite-discrete-element method publications are spread over a wide range of specialist journals and conferences. Thus in this paper, the main features of a selection of algorithmic breakthroughs are reviewed for the first time, enabling researchers in different fields to apply these compatible developments to their specific applications.