Otites externes nécrosantes: Apport de l’imagerie isotopique

Objective : the Necrotizing (malignant) External Otitis is a very serious, potentially lethal affection. It touches exclusively a debilitated population, where from the necessity of a premature and reliable diagnosis for a beam of cliniquo-biological, radiological and isotopic arguments. Its care as well as its treatment are heavy and require a better definition of themoment of cure. The purpose of our work is to specify the place of the isotopic explorations in the care of the NEO.Materials and methods : we report a retrospective study bringing together 29 patients hospitalized for suspicion of necrotizing external otitis of period going from 2003 till 2009.Résultats : the Middle Age of our population is 64.2 years, with a clear male prevalence. The majority of our patients are diabetics (90% of the cases) with a cardiac and hypertensive Co-morbidity among 19 patients. All our patients consulted, within 47 average days. An assessment of imagery was carried out, comprising a scanner for 16 of our patients. It wasnormal in 4 cases and had shown lesions of osteitis in 12 cases. The osseous scintigraphy marked in MDP-Tc99 was carried out among 24 patients, within 9.69 average day. It was positive for all our patients, objectifying an osseous hyperfixation. All our patients received an adapted treatment. After amendment of the clinico-biological signs, a scintigraphy in Ga67 was practiced for 16 patients within 74 average days. It confirmed the cure among 12 patients, at which one decided to stop the antibiotic therapy. In the other cases, it objectified an osseous hyperfixation translating the persistence of the active infectious process, from where prolongation of the treatment.Conclusion : it comes out from our work that the imagery is essential to confirm the diagnosis and to specify the extent of the osteitis. Indeed, the scanner and the MRI offer an excellent resolution and evaluate the extension of the infection perfectly. However, because of their poor sensitivity, they have little interest to the early phase of the diagnosis and for the therapeutic follow-up. The osseous scintigraphy has the advantage of an excellent sensitivity, approximately 100% in particular at the early stage, but is not specific. The tomographic techniques (SPECT) and the quantification improve however its specificity. The scintigraphy with gallium 67 seems quite as sensitive as and more specific than the osseousscintigraphy, especially if it is quantified, and appears essential with the therapeutic follow-up. Its standardization would have an excellent predictive value of cure, allowing the stop of the antibiotic therapyKeywords : Necrotizing External Otitis, scintigraphy with gallium, the osseous scintigraphy

Composition of plasma-sprayed tungsten coatings on CuCrZr alloy

Mock-ups for the International Thermonuclear Experimental Reactor(ITER) were manufactured by depositing W coatings on tubular substrates of CuCrZr alloy via plasma spraying. An appropriate interlayer (of Ni, Al and Si) was optimised to increase the adhesion of W on the Cu alloy and to provide a soft interface with intermediate thermal expansion coefficient for better thermo-mechanical compatibility. The distribution of chemical elements in the layered interface and in the coating was investigated by energy dispersive spectroscopy (EDS), XPS and AES in the as-preparedmaterial and after heat treatment of 24 h at 823 K. Moreover, the external Wlayer was examined by inductively coupled plasma emission spectrometry(ICP-ES). The results showed that the as-prepared material does not exhibit macro-porosity. The layers forming the interface do not exhibit any long-range diffusion of the chemical species from layer to layer during the deposition process. The heat treatment does not seem to cause long-rangemigration of Al and Ni into theWcoating. The presence of Ni (0.4wt%) in the as-deposited externalWlayer as shown by ICP-ES is only due to the low purity (commercial grade) of W powders used in spraying operations. It can be eliminated by using W powders of higher purity in the deposition process

Anelastic phenomena at the fibre-matrix interface of the Ti6Al4V-SiC composite

The composite, consisting of Ti6Al4V matrix reinforced by unidirectional SiC fibres (SCS-6), has been investigated by mechanical spectroscopy at temperatures up to 1,173 K. For comparison, the same experiments have been performed on the corresponding monolithic alloy. The internal friction (IF) spectrum of the composite exhibits a new relaxation peak superimposed to an exponentially increasing background. This peak, which is not present in the monolithic alloy, has an activation energy H = 186 kJ mol-1 and a relaxation time 0 = 2.3 x 10-15 s. The phenomenon has been attributed to a reorientation of interstitial-substitutional pairs in the  phase of Ti6Al4V matrix around the fibres. This explanation is supported by the results of micro-chemical characterization carried out by X-ray photoelectron spectroscopy (XPS) combined with Ar ion sputtering

Rivestimenti spessi di W su CuCrZr per applicazioni nei futuri reattori per fusione nucleare

Sono stati realizzati simulacri per ITER (International Thermonuclear Experimental Reactor) depositando viaPlasma Spraying rivestimenti di W su substrati tubolari di lega CuCrZr. E’ stato ottimizzato uno stratointermedio di Ni, Al e Si per accrescere l’adesione del W sulla lega di Cu e fornire un’interfaccia con coefficientedi espansione termica intermedio. La struttura dello strato intermedio e la distribuzione degli elementi chimicial suo interno e nel rivestimento è stata studiata mediante SEM, EDS, XPS, AES e ICP-ES, nel materiale talquale e dopo un trattamento termico di 24 ore a 550 °C. I risultati evidenziano che il materiale tal quale nonha macroporosità e che non c’è diffusione a lungo raggio degli elementi chimici dovuta al processo dideposizione. Il trattamento termico non sembra indurre migrazione di Al e Ni nel rivestimento di W.La caratterizzazione è stata completata mediante misure di diffrazione dei raggi X in temperatura fino a 425°C che mostrano come il rivestimento possa sopportare le tensioni che insorgono per il diverso coefficiente diespansione termica di Cu e W

Surface modification of austenitic steels by low temperature carburization

Austenitic stainless steels are characterized by good corrosion resistance in different environments but their use is limited due to low hardness and poor wear resistance. Conventional thermo-chemical surface treatments for improving the mechanical strength of steels induce Cr carbide precipitation thus are detrimental to corrosion resistance. A low temperature (< 470 °C) plasma treatment has been developed to overcome the problem with reduced costs and time of process. This paper shows the results of a microstructural characterization performed on a series of AISI 316L steel samples treated by plasma-assisted low temperature carburization in different conditions. Micro-hardness tests and X-ray diffraction (XRD) indicated that the best operative condition is achieved by employing a gas mixture with 2% of CH4 in H2. XPS and AES were used to examine the chemical composition of the 20 m-thick hardened layer. The results revealed that such layer is not homogeneous because a 2 m-thick overlayer forms on the surface exhibiting a typical graphitic nature. Furthermore, only the plasma treatment with 2% of CH4 guarantees that the whole carbon remains in solid solution whereas for higher CH4 amounts in the gas mixture carbide precipitation takes place

Surface modification in austenitic stainless steels treated by low-temperature carburization techniques

AISI 316L austenitic stainless steel is widely used in industrial applications, usually in contact with corrosive environments. Low temperature carburization (LTC) is a treatment increasingly applied to these steels in order to harden the surface without decreasing the corrosion resistance.In the present work, LTC techniques such as industrial and plasma-assisted treatments were applied to stainless steel and compared for their resistance to corrosion. The micro-chemical composition of hardened layer before and after corrosion treatments was studied on both the samples by surface-sensitive XPS and AES techniques. The results of plasma-assisted LTC treatment showed similar behavior of corrosion resistance as industrial LTC treatment. Hence, the plasma-assisted LTC treatment can be a suitable replacement for the industrial LTC treatment of stainless steel