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Le conteneur est un emballage reutilisable qui doit permettre d’assurer le maintien de la sterilite jusqu’au point d’utilisation. Afin de verifier la preservation des performances de ces emballages, certaines unites de sterilisation utilisent le test de fuite a l’eau. A ce jour, ce controle de fonctionnalite n’est ni retenu, ni reconnu par les fabricants. L’objectif de ce travail est de verifier le maintien de la sterilite a l’interieur des conteneurs lorsque le test de fuite est positif (rupture d’etancheite cuve/couvercle). Afin d’identifier les conditions pouvant modifier l’efficacite de la barriere microbienne, les variations de pression et de temperature ont ete relevees lors du stockage et transport. Au total, 5 series de 3 conteneurs (temoin positif sans barriere filtrante, conteneur avec test de fuite a l’eau negatif et positif) ont ete exposees, apres sterilisation, a un aerosol de Micrococcus luteus dans une chambre etanche a differentes pressions : 25, 50 et 75 mbar. Prealablement, des plaques de gelose etaient disposees au fond des conteneurs puis mises en culture apres exposition pendant 5 jours a 37°C. Les resultats en UFC ont ete convertis en facteur de reduction logarithmique (LRV) afin d’apprecier l’efficacite de la barriere filtrante. Les resultats confirment que la surpression est un facteur favorisant de la penetration de microorganismes dans les conteneurs. D’autre part, les conteneurs presentant un test positif sont significativement plus contamines que des conteneurs disposant d’une etancheite parfaite (p-valeur=0,002). Le test de fuite a l’eau peut donc etre considere comme discriminant pour evaluer le maintien des performances des conteneurs.

Background Since biosimilar infliximab’s arrival on the market in 2015, health authorities promote their prescription. The question arises of the medico-economic interest of the switch from an originator to its biosimilar in patients already treated. The NOR-Switch study gives us an answer in showing the non-inferiority of biosimilar CT-P13 against the originator in terms of effectiveness and tolerance. Since biosimilar (Inflectra) referencing in our hospital in 2015, all treatment initiations are done with the biosimilar and a switch is proposed to patients already treated with the originator (Remicade). Purpose To evaluate the economic impact of introducing the biosimilar infliximab in our hospital. Material and methods We made an evaluation between June 2015 (biosimilar arrival) and 2018 to measure the impact of this referencing. We used a prospective database since 2014 concerning all infliximab injections ((Remicade+Inflectra), patient, indication, number of vial per injection, cost). Results Patients are treated in rheumatology (83%) and gastrology (17%): rheumatoid arthritis, Ankylosing spondylitis, Crohn’s disease and haemorrhagic rectocolitis. Since 2014, vial consumption (annual and by injection) of infliximab has risen (+8% per year, from 1641 vials to 2117). The partition between biosimilar and originator has evolved since 2015: the biosimilar proportion has increased from 8% (160 vials) to 55% (1056). In addition to treatment initiation, we note a 30% switch in patients already treated by Remicade. Inflectra was introduced with a −36% price in comparison with Remicade. Since 2015, vial cost has decreased (−40% for both biosimilar and originator). Although the consumption grew, we observed an annual cost reduction of −15%. Since 2014, infliximab expenses diminish from €8 50 000 to €5 00 000 yearly. Due to the introduction of the infliximab biosimilar in our hospital, we estimate a cost savings of €1.1 million in 3 years. The maintenance rate is respectively 57% and 64% under Inflectra and Remicade. Conclusion Since 2015, infliximab consumption has increased but a lower price and health authorities’ promotion for biosimilars contribute to a cost reduction in both Remicade, Inflectra and, consequently, annual cost. This cost saving is helped by prescriptors’s willingness: systematic treatment of naive patients by biosimilar and switch proposal to patients already treated. Biosimilar referencing and prescription are part of the cost-saving approach: less money is therefore spent on more treated patients. References and/or acknowledgements No conflict of interest.

International audience; The ATLAS Collaboration has started a vast program of upgrades in the context of high-luminosity LHC (HL-LHC) foreseen in 2024. The current readout electronics of every sub-detector, including the Tile Calorimeter, must be upgraded to comply with the extreme HL-LHC operating conditions. The ASIC described in this document, named Front-end ATlAs tiLe Integrated Circuit (FATALIC), has been developed to fulfill these requirements. FATALIC is based on a 130 nm CMOS technology and performs the complete signal processing (amplification, shaping and digitization) over a large dynamic range. A dedicated channel for low current is also designed to perform the detector calibration with a radioactive cesium source. The design and performances of FATALIC are described including test beam data analysis.

The objective is to check the maintaining performance of filter barrier in sterilizations containers with the leakage rupture the junction tank/lid of the container. In order to control the good sealing performance, we use the water leak test as described in the normative document AFNOR FD S98-053. Does the leakage rupture cause the contamination of containers during the storage or transport between two sterilization units?We use 5 sets of 3 different containers (the first without barrier system (positive control), the others with barrier system (the second with positive water test and the third with negative water test)). The containers are sterilized after having positioned triptyc soy agar (TSA) plates at the bottom. In a closed chamber test, the containers are exposed with an aerosol of Micrococcus luteus under stress of an overpressure (25, 50 or 75 mbar) simulating atmospheric pressure variations. Each triptyc soy agar (TSA) plates are incubated during 5 days at 37°C for bacterial identification.At 25 mbar, 74% of containers having a leakage with a water test let the microorganisms ingress despite the filter barrier. The results confirm that the overpressure increases the level of bacteria in containers. Furthermore, the containers with positive water test are more contaminated than containers with perfect sealing. The effectiveness of the sterile barrier system is evaluated by the logarithmic reduction value (LRV).The water test could be a good indication to evaluate the effectiveness of the sterile barrier system of rigid sterilization containers.

The present article introduces a novel ASIC architecture, designed in the context of the ATLAS Tile Calorimeter upgrade program for the High-Luminosity phase of the Large Hadron Collider at CERN. The architecture is based on radiation-tolerant 130 nm Complementary Metal-Oxide-Semiconductor technology, embedding both analog and digital processing of detector signals. A detailed description of the ASIC is given in terms of motivation, design characteristics and simulated and measured performance. Experimental studies, based on 24 prototype units under real particle beam conditions are also presented in order to demonstrate the potential of the architecture as a reliable front-end readout electronic solution., 32 pages

Resume Transrectal drainage of pediatric pouch of Douglas abscesses under suprapubic US guidance: technique and results J Radiol 2010;91:221-5 J Potet, S Franchi-Abella, M Al Issa, C Fayard et D Pariente Pelvic abscesses are not always amenable to percutaneous drainage. Transrectal drainage of pouch of Douglas abscesses, performed blindly by surgeons for many years, is not familiar to radiologists. The purpose of this article is to describe our technique for the drainage of pouch of Douglas abscesses under suprapubic US guidance and report our results in a series of 7 pediatric patients with deep pelvic abscess not amenable to percutaneous drainage after failure of antibiotics. The procedure was performed under general anesthesia. All procedures were successful and without complication. The drainage catheter was well tolerated in all cases with short post-drainage hospital stay. After failure of medical management, this technique can be used irrespective of patient age or sex using US transducers and drainage catheters routiney available in any radiology department. Les abces pelviens ne sont pas toujours accessibles au drainage percutane. Le drainage transrectal des abces du cul-de-sac de Douglas, pratique depuis longtemps par les chirurgiens a l’aveugle, est mal connu des radiologues. L’objectif de cet article est de decrire notre technique de drainage par voie transrectale des abces du cul-desac de Douglas sous controle echographique sus-pubien et de rapporter nos resultats sur une serie de 7 enfants, porteurs d’un abces sous tension non accessible a la ponction percutanee et apres echec d’une antibiotherapie adaptee, La procedure est faite sous anesthesie generale. Le drainage a ete un succes d’emblee dans tous les cas, sans complication, avec un drain bien tolere et une duree d’hospitalisation courte au decours Apres echec du traitement medical, cette technique est applicable quel que soit le sexe et l’âge, avec des sondes d’echographie et du materiel de drainage disponibles dans tout service de radiologie.

The dependence of the d(e,e{prime}K{sup +}) reaction cross sections on the hyperon-nucleon interactions is investigated. It is shown that the data obtained with Longitudinal-Transverse separation or polarized photons can distinguish a class of Nijmegen models of hyperon-nucleon interactions which are {chi}{sup 2}-equivalent in fitting the existing 35 data points of hyperon-nucleon reactions.

Previous approaches to the photo- and electro-production of strangeness off the proton, based upon effective hadronic Lagrangians, are extended here to incorporate the so called off-shell effects inherent to the fermions with spin >= 3/2. A formalism for intermediate-state, spin 3/2, nucleonic and hyperonic resonances is presented and applied to the processes $\gamma + p ---> K^{+} + \Lambda$, for $E_{\gamma}^{lab}$ e' + K^+ + \Lambda$, as well as the branching ratio for the crossed channel reaction $K^- + p ---> \gamma + \Lambda$, with stopped kaons. The sensitivity, from moderate to significant, of various observables to such effects are discussed., Comment: 38 pages in LaTeX2e-RevTeX + 8 postscript figures

We study the behavior of energy levels in two dimensions for exotic atoms, i.e., when a long-range attractive potential is supplemented by a short-range interaction, and compare the results with these of the one- and three-dimensional cases. The energy shifts are well reproduced by a scattering length formula $ \delta{E}= A_0^2/\ln (a/R)$, where $a$ is the scattering length in the short-range potential, $A_0^2/(2\,\pi)$ the square of the wave function at the origin in the external potential, and $R$ is related to the derivative with respect to the energy of the solution that is regular at large distances., Comment: Significant upgrade of the early version, with a new and more detailed derivation of the energy-shift formula, and all figures redrawn. To appear in J. Phys. A

At the SIS/ESR accelerator facility at GSI in Darmstadt the 4π-detector system FOPI is under construction at present. It is designed for the investigation of central collisions of heavy ions in the energy range up to 2 A GeV. As phase I of this detector a forward wall has been built and used in various experiments. It comprizes a total number of 764 scintillators with an additional shell of 188 thin ΔE -detectors in front of it and covers the full azimuth of the polar angles from 1° to 30°. The velocity and the nuclear charge of the fragments are determined by a combined time-of-flight and ΔE measurement.

The NN\ensuremath{\rightarrow}N\ensuremath{\Delta} reaction is investigated within the coupled \ensuremath{\pi}NN-NN theory. The model predictions for the differential cross section, production asymmetry, and spin-correlation parameters are compared with the Argonne data at ${\mathit{T}}_{\mathit{N}}^{\mathrm{lab}}$=0.57, 0.81, and 1.01 GeV. Short-range effects are introduced through the \ensuremath{\rho}-exchange contribution. The overall quality of the results is satisfactory, except for the triplet part of the production asymmetry at the two highest energies. The role of the $^{3}$${\mathit{F}}_{3}$${\ensuremath{\rightarrow}}^{5}$${\mathit{P}}_{3}$ amplitude in this problem is assessed.

Pelvic abscesses are not always amenable to percutaneous drainage. Transrectal drainage of pouch of Douglas abscesses, performed blindly by surgeons for many years, is not familiar to radiologists. The purpose of this article is to describe our technique for the drainage of pouch of Douglas abscesses under suprapubic US guidance and report our results in a series of 7 pediatric patients with deep pelvic abscess not amenable to percutaneous drainage after failure of antibiotics. The procedure was performed under general anesthesia. All procedures were successful and without complication. The drainage catheter was well tolerated in all cases with short post-drainage hospital stay. After failure of medical management, this technique can be used irrespective of patient age or sex using US transducers and drainage catheters routiney available in any radiology department.

The \ensuremath{\pi}NN system is studied with two-term potentials for the \ensuremath{\pi}N interaction in the ${\mathit{P}}_{33}$ and ${\mathit{P}}_{11}$ channels. Such model systematics as the difference in the dominant \ensuremath{\pi}N ${\mathit{P}}_{33}$ input, the effect of the so-called backward propagating pion, the choice of the relative momenta (magic vectors) at the isobar vertices, etc., are investigated. The results in the \ensuremath{\pi}d-\ensuremath{\pi}d, \ensuremath{\pi}d-NN, and NN-NN reactions at intermediate energies are compared with the available experimental data. The overall quality of the predictions by the present approach is roughly comparable to that based upon the one-term ${\mathit{P}}_{33}$ isobar model supplemented by an appropriate ad hoc off-shell modification, but with a significant improvement in the description of the \ensuremath{\pi}d-NN asymmetry ${\mathit{A}}_{\mathit{y}0}$.

The K−d elastic scattering at low energy is investigated within a fully relativistic three-body approach, using relativistic separable parametrizations for the YN and K N interactions.

$\Kbar N$ interactions are investigated {\it via} an effective non-linear chiral meson-baryon Lagrangian. The adjustable parameters are determined by a fitting procedure on the $K^-p$ threshold branching ratios and total cross-section data for $p^{lab}_K\le$ 250 MeV/c. We produce predictions for the $\Sigma \pi$ mass spectrum, and scattering lenghts $a_{K^-p}$, $a_n(K^-n \to K^-n)$, $a_n0(\Kbar0 n \to \Kbar0 n)$, and $a_{ex}(K^-p \to \Kbar0 n)$. The $\Kbar N$ amplitudes thus obtained, as well as those for other two-body channels ($\pi N$, $NN$, and $YN$) are used as input to predict the scattering length $A_{K^-d}$, for which we have devised a relativistic version of the three-body Faddeev equations. Results for all two- and three-body coupled channels are reported both in isospin and particle bases. All available $\Kbar N$ data are well reproduced and our best results for the $K^-p$ and $K^-d$ scattering lenghts are $a_{K^-p} = (-0.90 + i 0.87) fm$ and $A_{K^-d} = (-1.80 + i 1.55) fm$.

We report on the first calculation of the scattering length ${A}_{{K}^{\ensuremath{-}}d}$ based on a relativistic three-body approach where the $\overline{K}N$ coupled channel two-body input amplitudes have been obtained with the chiral $\mathrm{SU}(3)$ constraint, but with isospin symmetry breaking effects taken into account. Results are compared with a recent calculation applying a similar set of two-body amplitudes, based on the fixed center approximation, and for which we find significant deviations from the three-body results. Effects of the deuteron D-wave component, pion-nucleon, and hyperon-nucleon interactions are also evaluated.

Objectifs Rapporter deux cas de duplication rectale tubulaire communicante endo et exo pelvienne de diagnostic antenatal et discuter les diagnostics differentiels Sujet Exploration par echographie et l’IRM antenatales et postnatales et opacification rectale postnatale. Resultats Sur les explorations antenatales la masse endo et exopelvienne etait uniloculaire et de signal liquidien. A la naissance, l’imagerie met en evidence l’apparition d’air et de meconium dans la masse exopelvienne, et le lavement opaque confirme la communication avec le rectum. La prise charge initiale a ete une colostomie de decharge. Conclusion La duplication rectale communicante et exopelvienne est exceptionnelle, mais doit etre rajouter au diagnostic differentiel antenatal du teratome sacrococcygien.

Results of recent theoretical studies on the electromagnetic form factors of strange baryons and kaons are embodied in a strangeness electromagnetic production model based on an effective Lagrangian approach. The sensitivity of different observables that are the subject of current or planned measurements at JLAB, are investigated with respect to the phenomenological ingredients of the model.

Previous approaches to the photo- and electro-production of strangeness on the proton, based upon effective Lagrangian, is extended to incorporate the so called off-shell effects (OSE) required while dealing with spin ⩾3/2 baryonic resonances. Results for K+ Λ channels are presented.

A formalism, based on an isobaric approach using Feynman diagrammatic techniques, which includes the nucleonic (spin \ensuremath{\le} 5/2), hyperonic (spin 1/2), and kaonic resonances, is developed. Using this formalism, a thorough investigation of the following electromagnetic strangeness processes, for which experimental results are available, is performed: \ensuremath{\gamma}p\ensuremath{\rightarrow}${\mathit{K}}^{+}$\ensuremath{\Lambda}, ${\mathit{K}}^{+}$${\mathrm{\ensuremath{\Sigma}}}^{0}$, ${\mathit{K}}^{0}$${\mathrm{\ensuremath{\Sigma}}}^{+}$, for ${\mathit{E}}_{\ensuremath{\gamma}}^{\mathrm{lab}}$\ensuremath{\le} 2.1 GeV, ep\ensuremath{\rightarrow}${\mathit{e}}^{\ensuremath{'}}$${\mathit{K}}^{+}$\ensuremath{\Lambda}, ${\mathit{e}}^{\ensuremath{'}}$${\mathit{K}}^{+}$${\mathrm{\ensuremath{\Sigma}}}^{0}$, and ${\mathit{K}}^{\mathrm{\ensuremath{-}}}$p\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\Lambda},\ensuremath{\gamma}${\mathrm{\ensuremath{\Sigma}}}^{0}$. A reaction mechanism, describing well enough the data, is found to include a reasonable number of baryonic resonances among a very large number of potential candidates. The extracted main kaon-hyperon-nucleon coupling constants are in good agreement with values predicted using SU(3) symmetry. The main findings of this model are compared with the results of other recent phenomenological studies. Predictions for the upcoming photoproduction polarization and electroproduction observables are presented, and their sensitivity to the phenomenological models ingredients are emphasized. \textcopyright{} 1996 The American Physical Society.

Starting from an appropriate low energy model, we investigate the role played by spin‐3/2 nucleonic resonances. A new model is obtained giving good agreement with data up to 2.1 GeV and satisfying SU(3) constraints on the main coupling constants.

A formalism, based on an isobaric approach, via Feynman diagrammatic technique, including the nucleonic (spin ≤ 5/2), hyperonic (spin 1/2) and kaonic resonances is developed. Using this formalism, a thorough investigation of all the electromagnetic strangeness processes, for which experimental results are available, is performed and satisfactory agreement with the data is obtained. The reaction mechanism is found to include a reasonable number of baryonic resonances, with the extracted main kaon-hyperon-nucleon coupling constants in agreement with the SU(3)-symmetry predictions. The sensitivity of this model to the form factors of the relevant hadrons is emphasized.

Investigations in progress on the associated strangeness photo‐ and electroproduction of the proton in the few GeV region and the negative kaon radiative capture are reported, and results for the K+∑0 channel are presented.

Objectifs Le drainage transrectal des abces du CDS de Douglas, pratique depuis longtemps par les chirurgiens a l’aveugle, est mal connu des radiologues. Nous rapportons une serie pediatrique sous guidage echographique. Materiels et methodes Etude retrospective de 1998 a 2008, incluant des enfants porteurs d’un abces du CDS de Douglas sous tension apres echec d’une antibiotherapie adaptee. Drainage de l’abces sous anesthesie generale avec mise en place d’un drain multiperfore (8 ou 10F) par voie transrectale au travers d’une canule rectale sous guidage echographique sus-pubien. Resultats Sept enfants âges en moyenne de 11,2 ans, avec 6 abces post appendicectomie et un hematome surinfecte. Cinq abces sous-tension medians, 2 lateralises. Volume moyen : 170 ml. Delai moyen entre appendicectomie et drainage : 11,5 jours. Succes du drainage chez tous les patients, sans complication. Normalisation clinique dans les 48 heures. Drain bien tolere, elimine en moyenne a 3,7 jours. Duree d’hospitalisation moyenne au decours : 7,3 jours. Conclusion Le DTREG a ete possible, efficace et bien tolere dans notre serie. Apres echec d’une antibiotherapie, dans les abces sous tension du CDS de Douglas, cette technique est applicable quels que soit le sexe et l’âge, avec des sondes d’echographie disponibles sur tout echographe.

There has been a long-standing problem in the coupled \ensuremath{\pi}NN-NN theory concerning its apparent failure in reproducing the tensor polarization ${T}_{20}$ in the elastic \ensuremath{\pi}d scattering at medium energies. A mechanism recently proposed by Jennings to solve this problem is examined. It is then found that it comes from the positive-energy pole in one of the nucleon propagators in the exchange impulse diagram within the covariant picture which is usually overlooked when devising the spectator on-mass-shell approximation, and that it does not lead to the claimed near cancellation of the Pauli exchange contribution, but is important to be included. The inclusion of this contribution is shown to considerably improve in reproducing the pion-deuteron spin observables including ${T}_{20}$, particularly above the delta resonance energy.

Exact calculations of vector and tensor polarizations are presented for the reaction π + d → π + d at T π = 142 MeV. They are aimed at meeting the apparent demand raised by upcoming pertinent experiments. The effects of (i) deuteron D state, (ii) participating π-N partial waves and (iii) coupling of different π-d orbital angular momenta are found to be very important.

This chapter focuses on Coulomb energy of 3 He. The AGS quasiparticle method provides a way to include the Coulomb interaction in the three-nucleon system, especially, as demonstrated by Alessandrini and Zankel, if only two charged nucleons are present in the three-body system. The method takes into account the Coulomb force exactly, and so the usual Coulomb singularity problem arises. As there is still no manageable exact treatment of the Coulomb many-body system available, the Coulomb singularity is circumvented by using a Yukawa type cutoff. Considering the small internucleon distances in the three-nucleon bound state, it seems to be plausible that the long-range Coulomb singularity rather weakly influences the three-nucleon binding energy. Switching off all Coulomb contributions in the 3 He, assuming charge symmetry of the nuclear forces, a model is obtained for the triton. The binding energy difference of 3 H and 3 He is then the Coulomb energy ( E C ) of He. The chapter illustrates the effective potential of 3 He.

We have investigated the Phillips' plot with different types of nonlocal separable interactions (up to rank 6) in the3S1-3D1 channel. We have then included all theP-wave contributions with rank-one interactions. The effect appears to be weak on the triton binding energy but nonnegligible on the doublet scattering length.

The ..pi..d elastic scattering observables are calculated in the 142 to 256 MeV energy range within a relativistic three-body theory without ..pi.. absorption. The nonresonant ..pi..N partial waves are included perturbatively to an excellent degree of accuracy. Various NN tensor forces are elaborated at different levels of quality. The sensitivity of elastic differential cross sections and polarization parameters to the description of the NN and ..pi..N channels is investigated. The importance of using a realistic deuteron wave function is demonstrated.

We calculate the pion-deuteron elastic scattering at E/sub ..pi../= 142 MeV using nonrelativistic three-body equations in which relativistic kinematics are retained only for the pion. The NN tensor force is taken into account, and, for the first time, all S and P ..pi..N partial waves are included in an axact way. The coupling between l = J +- 1..pi..d channels is found to be not negligible, and we establish the large interference effects of all other than P/sub 33/..pi..N channels leading to a rather good description of the experimental data E/sub ..pi../= 142 MeV.

The theory of the coupled \ensuremath{\pi}NN-NN systems is applied to the unified description of the \ensuremath{\pi}d-\ensuremath{\pi}d, \ensuremath{\pi}d-NN, and NN-NN reactions in the intermediate energy range. Off-shell modifications are introduced in the ${P}_{33}$ and ${P}_{11}$ \ensuremath{\pi}N channels and the effects of heavy meson exchange are investigated. In general, results for various observables are in agreement with experiments. We have assessed certain aspects upon which future work should improve.

We show the great sensitivity of the πd elastic-scattering observables to the details of the deuteron wave function. At 142 MeV and 256 MeV we find that the differential cross-section at θc.m.=180° depends linearly upon the quantityA(q2), which is the most important part of the deuteron electromagnetic form factor. A similar behaviour appears for the tensor polarizationt20(180°) at 142 MeV. Our results are compared with existing experimental data at backward angles.

The Faddeev--Lovelace equations have been solved for the A = 6 system with the use of new N--..cap alpha.. separable interactions. The /sup 6/Li spectrum is given and the (d--..cap alpha..) elastic scattering observables (angular distributions, vector and tensor polarizations) are calculated and compared with recent experimental data. A noticeable improvement on Shanley's results is obtained.

The effect of the coupling to the ..pi..d channel on the intermediate energy NN scattering is studied using the recent NN..-->..NN and NN..--> pi..d partial wave analyses as well as the coupled NN..--> pi..NN theory. Contrary to some recent claims, it is found that this coupling is important in the /sup 1/D/sub 2/ and /sup 3/F/sub 3/ partial waves in which the intermediate N..delta.. configuration dominates.

The ..pi..d elastic scattering observables are calculated in the energy range 25 to 180 MeV on the basis of the Faddeev-Lovelace equations where relativistic kinematics are used only for the pion. In the (3,3) resonance region, the importance of all S, P ..pi..N channels (included in an exact way) and the sensitivity to the description of the deuteron wave function are demonstrated. The vector and tensor polarizations are predicted at 142 and 180 MeV.

Une methode rapide et economique d'evaluation des lubrifiants et des combustibles vis-a-vis de l'usure par polissage des cylindres de moteurs diesel suralimentes a ete mise au point sur moteur monocylindre de laboratoire dans le cadre d'une convention de recherche Societe Nationale Elf Aquitaine - Institut Francais du Petrole (SNEA-IFP). Cette methode referencee IFP-UP-4/80, permet egalement de juger de la tendance a la formation de depots et au gommage, de l'usure des segments et de la tendance a la consommation d'huile des lubrifiants. Elle est en bonne correlation avec l'essai CEC-Ford Tornado et discrimine tres bien les huiles de reference RL 47 et RL 48 du Conseil Europeen de Coordination (CEC). Elle a permis l'etude du mecanisme de l'usure par polissage en recherchant l'influence de parametres essentiels : - Constitution du lubrifiant : le phenomene est influence par la nature de l'huile de base et par sa viscosite, par la quantite de polymeres ameliorant l'indice de viscosite et surtout par le choix des additifs detergents. En premiere approximation et pour des familles d'huiles homogenes, l'usure par polissage augmente lorsque la stabilite thermique de l'huile diminue. - Fonctionnement du moteur : le polissage croit tres vite avec la charge du moteur a partir d'un certain seuil, son evolution en fonction du temps, observee par cotation endoscopique, presente une allure caracteristique en S, le polissage commence du cote poussee et en haut du cylindre. - Constitution du combustible : l'augmentation de la teneur en soufre du gazole diminue fortement l'usure par polissage provoquee par une huile reputee mauvaise sur ce plan mais est sans effet sur une bonne huile. - Etat de surface du cylindre : le prepolissage de la chemise par pierrage extremement fin ne conduit pas aux memes phenomenes que ceux observes lorsque la chemise est polie in situ dans le moteur en fonctionnement. En particulier, l'usure des segments ainsi que les debits de gaz de soufflage, sont plus faibles qu'avec une chemise normale. Enfin, le mecanisme de l'usure par polissage par abrasion douce a deux et a trois corps est parfaitement confirme par une exploration micrographique et une microanalyse des surfaces polies.