Linking disease epidemiology and livestock productivity: the case of bovine respiratory disease in France

Concerns are growing over the impact of livestock farming on environment and public health. The livestock industry is faced with the double constraint of limiting its use of natural resources and antimicrobials while ensuring its economic sustainability. In this context, reliable methods are needed to evaluate the effect of the prevention of endemic animal diseases on the productivity of livestock production systems. In this study, an epidemiological and productivity model was used to link changes in Bovine Respiratory Disease (BRD) incidence with the productivity of the beef and dairy cattle sectors in France. Cattle production parameters significantly affected by BRD were selected through literature review. Previous field study results and national cattle performance estimates were used to infer growth performances, mortality rates and carcass quality in the cattle affected and not affected by BRD. A steady-state deterministic herd production model was used to predict the productivity of the dairy and beef sector and their defined compartments (breeding-fattening, feedlot young bulls, and feedlot veal) in case of BRD incidence reduction by 20%, 50% or 100%. Results suggested that BRD should be controlled at a priority in beef breeding farms as eradication of BRD in beef calves would increase the whole beef sector’s productivity by 4.7–5.5% while eradication in other production stages would result in lower productivity gain in their respective sectors. However, the analysis performed at compartment level showed that, in both the beef and dairy sector, young bull and veal feedlot enterprises derive more economic benefits from BRD eradication for their own compartment (increase in productivity of 8.7–12.8% for beef young bulls) than the breeding farms (increase in productivity of 5.1–6% for beef calves), which may limit the investments in BRD control

Dispersed polypyrrole latex as a cathode material for all-solid-state lithium batteries

Fine bare polypyrrole latex (200 nm sized) was obtained by improved synthesis conditions. This new electronically conducting electroactive material was dispersed in a polyoxyethylene solid salt solution and used as a battery cathode together with a polymer electrolyte film and a lithium sheet in a threelayered system. The resulting battery behaves very well at low current densities though an incomplete dispersion of the latex has been seen from studies on symmetrical cells (using latex composite for both electrodes). A self-discharge problem for the lithium cells arose only before the first discharge and during subsequent charge processes. A previously described theoretical model was used to estimate the ionic diffusion coefficient within the polypyrrole particles. The very low value - 10-13 cm2.s-1 - obtained explains the poor performances of this material at moderate current densities

Control of the interface properties of polypyrrole substituted by peptides

The condensation of (pyrryl-3) acetic acid with amino-acid esters leads to new pyrrole derivatives the electropolymerisation of which results in conducting films. The electroactivity in aqueous electrolyte of these new materials depends upon the molecular substituent. This behaviour is directly related to the variable hydrophobic character of the amino-acids

New functionalized oligothiophenes. Properties and applications to photodetection

A series of oligothiophenes nT(up to 6T) substitued at the ends of the chain by electronic donors(D) or acceptors(A) has been prepared. The electrochemical study of the soluble species allowed us to quantify the effect of substituents. The optical properties of the compounds have shown the existence of charge transfers at the excited state. The semiconducting properties of thin films have been investigated in the aim of applications in electronic devices. The photosensiblity in symmetrical and unsymmetrical contacts has been studied in visible area. The low junction yield (18%) suggests substantial trapping and recombination rate

Synthèse et propriétés des deux formes énantiomères de poly(thiophènes) chiraux

La synthèse des deux énantiomères de poly(thiophènes) chiraux a été réalisée. Ces matériaux peuvent reconnaître stéréo-sélectivement des anions chiraux lors de cycles voltamétriques

Properties of Adsorbed Bovine Serum Albumin and Fibrinogen on Self-Assembled Monolayers

International audienceWe have studied kinetics of adsorption and properties of adsorbed bovine serum albumin (BSA) and fibrinogen (Fb) on a hydrophobic octyl surface, a hydrophilic amine surface, and a mixture of octyl and amine self-assembled monolayer (SAM) and newly synthesized hybrid SAM by using quartz crystal microbalance (QCM). In addition, we have proposed a combined kinetic and mass transfer constrained protein adsorption model. The model is fitted to a change in resonance frequency, Delta F-n/n versus time data obtained from QCM to get the kinetic rate constants, mass transfer coefficient, and spreading of adsorbed proteins. Initial rate of adsorption increases with a decrease in surface energy of the substrate. The equilibrium adsorbed amount of BSA on the hybrid surface is less than that on the mixed surface and lies in between that on octyl and amine surfaces and that of Fb is the least on hybrid surface. The analysis of variation of the dissipation factor, Delta D, with Delta F-n/n indicates that BSA is more flexible than Fb and the adsorbed layer of both proteins is softest on the hybrid surface. The relaxation times of adsorbed proteins are the slowest on the octyl surface, while those on the hybrid surface are the fastest. The analysis of secondary structures of proteins using ATR-FTIR suggests secondary structures of the proteins change during adsorption. The content of alpha-helix of the proteins increases due to adsorption on the amine surface, while that decreases on all other surfaces. The total content of a-helix and beta-sheet strongly depends on the adsorbed mass of the proteins and is weakly dependent related to elasticity and viscosity of the adsorbed proteins, respectively

Electrodeposition de nanostructures 0 et 1D de SnO2 pour la détection électrochimique sans marquage d’ADN : influence de la dimensionnalité sur le signal d’impédance

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Ionic conductivity of polymer electrolytes obtained by polycondensation from PEGs; Redox properties induced within a polyether-aryl

International audiencePolycondensates were prepared by reacting several polyethyleneglycols, PEG, with 3-chloro-2-chloromethyl-1-propene. After cross-linking and salt dissolution, the ionic conductivity was investigated together with the thermal behaviour of the polymers, according to the ratio of PEG400 blocks in the polycondensates. The best conductivities were obtained for the highest contents in long PEG blocks. 9, 10-bis(chloromethyl)anthracene was used in the same way to prepare redox solvating polycondensates. The redox properties of the resulting polycondensates were characterized by cyclic microvoltammetry. An electron hopping transport between redox sites has been set up