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Decommissioning of nuclear facilities incurs high costs regarding the accurate characterisation and correct disposal of the decommissioned materials. Therefore, there is a need for the implementation of new and traceable measurement technologies to select the appropriate release or disposal route of radioactive wastes. This paper addresses some of the innovative outcomes of the project “Metrology for Decommissioning Nuclear Facilities” related to mapping of contamination inside nuclear facilities, waste clearance measurement, Raman distributed temperature sensing for long term repository integrity monitoring and validation of radiochemical procedures.

Highly efficient inverted organic light-emitting diodes (iOLEDs) are reported by including in the structure a surface modifier, polyethylenimine-ethoxylated (PEIE), to decrease the cathode work function and a hole blocking layer, 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi) to increase the efficiency of the device. The two compounds have been processed in a single step, by using a mixture PEIE:TPBi spun from the same solution. It is demonstrated by time-of-flight secondary-ion mass spectrometry (TOF-SIMS) that a bilayer is formed and same performances as the separately processed materials are obtained. This technic enables to reach high luminances (40 000 cd m−2) and high current efficiencies (13 cd/A) using the conjugated Super Yellow (SY) polymer as the emissive layer while reducing the number of processing steps.

In the present study single crystals of rhombohedral alpha-B were investigated under pressure to 60 GPa by means of single-crystal X-ray diffraction. The bulk modulus of alpha-B was found to be K=224(7) GPa (K'=3.0(3)). Measurements of interatomic distances as a function of pressure revealed that the intericosahedral two-center two-electron (2c-2e) bonds are almost as stiff as some of intraicosahedral ones. The three-center two-electron (3c-2e) intericosahedral bonds show much higher compliance compared to other bonds in alpha-B. The vibrational properties of alpha-B under pressure were investigated by Raman spectroscopy at pressures up to 160 GPa and IR spectroscopy at pressures up to 53 GPa.

OBJECTIVES: We modeled the potential impacts of bouillon fortification with different levels of vitamin A, folic acid, vitamin B12, iron, and zinc on dietary micronutrient adequacy to inform multi-stakeholder discussions around bouillon fortification programs. METHODS: We used individual dietary intake data in Cameroon from women of reproductive age (WRA) and children 1–5 y (n = 902 and 872), and household (HH) survey data in Cameroon (n = 11,384 HH), Ghana (n = 11,870 HH), and Haiti (n = 4,951 HH) to estimate micronutrient (MN) intake. The Adult Male Equivalent method was applied to estimate “apparent intake” of WRA, children, and men from HH surveys. We examined intake of bouillon and calculated prevalence of inadequate (below the estimated average requirement) and high (above the tolerable upper intake level, UL) micronutrient intake. Analyses included the contributions of mandatory fortification of oil or wheat flour at estimated current micronutrient levels. We simulated the impacts of bouillon fortification with varying levels of vitamin A, folic acid, vitamin B12, iron, and zinc on inadequate and high intakes of each nutrient. RESULTS: Bouillon was commonly consumed in all countries, with any reported consumption ranging from 67–81% in Ghana to over 90% in Cameroon and Haiti. Median (apparent) bouillon consumption ranged from 1.6–2.1 g/d for women, 0.7–1.0 g/d for children, and 1.8–2.2 g/d for men. Bouillon fortification with vitamins was predicted to reduce dietary inadequacy (120 μg/g vitamin A: 15–33 percentage points, pp, depending on the country and target group; 80 μg/g folate: 11–33 pp; 1.2 μg/g B12: 12–67 pp) with minimal risk of high intake. In contrast, predicted effects on dietary iron inadequacy were modest (5–12 pp reduction at 5 mg iron/g, assuming 2% absorption). Simulated zinc fortification showed reductions in inadequate absorbable zinc intake (14–42 pp at 3 mg/g), but children's intakes commonly exceeded the UL. CONCLUSIONS: Modeling suggests that bouillon fortification could reduce inadequate MN intakes in these countries. Further work is needed to identify fortification levels that will meet criteria for nutritional benefits, technical feasibility, and cost-effectiveness. FUNDING SOURCES: This analysis was supported by a grant to UC Davis from Helen Keller International.

International audience; The Lophiodontidae are a European Eocene perissodactyl family that includes the genera Lophiaspis, Lophiodon and Paralophiodon. Despite their high specific diversity, their abundance and their dominance over Eocene large herbivores, the origin of this group still remains unclear. The La Borie locality (early Eocene, MP8-9), near Issel, Southern France, has yielded a new and well preserved skull of a new early lophiodontid. Building on this new specimen, a new phylogenetic hypothesis is proposed for Lophiodontidae, based on a cladistic analysis of dental, cranial and mandibular characters. The specimen displays a unique morphology that leads us to propose the new genus and species Eolophiodon laboriense. This monospecific genus is the sister group of the clade gathering Lophiodon and Paralophiodon. From the obtained phylogeny, it is proposed that the well-known group of derived lophiodonts might have arisen in Southern Europe soon after the origin of the family, and most probably from a Lophiaspis-like stock.

Simulations with the software Synchrotron Radiation Workshop (SRW) for the ANKA infrared (IR) beamlines IR1 and IR2 have shown, that the far-IR and terahertz (THz) edge radiation can interact with the vacuum chamber walls very close to the electron beam. Unfortunately SRW cannot compute wavefronts at large angles of observation and at a close vicinity to the source. As we need to take into account these perturbations for the further propagation of the radiation through the entire beamline optics to the experimental station, we have started to develop our own code. This code can generate the electric and magnetic field vectors by solving Maxwell equations without approximations and without restrictions to the angles of observation or distance to the source. In particular the latter requires that also the magnetic field vectors have to be calculated, to obtain the corresponding photon intensity distribution for situations where the electron beam intersects the observation plane. Moreover it revealed that it is essential to correct for the Coulomb field prior to calculating the photon intensity in cases where the electron beam intersects the observation plane. Therefore our code is not limited to synchrotrons but can also be used for the development of new kinds of IR/THz radiation facilities.

La rehabilitacion en la arteriopatia de los miembros inferiores se basa en programas personalizados que asocian readaptacion al esfuerzo y educacion terapeutica. Aumenta las capacidades fisicas, sobre todo la distancia de la marcha, permite reanudar las actividades, reduce los factores de riesgo y mejora los frecuentes trastornos del estado de animo que se observan en estos pacientes. Mejora las anomalias fisiopatologicas, en especial el desequilibrio neurovegetativo y la disfuncion endotelial. Se recomienda un programa ambulatorio de al menos tres sesiones por semana durante 2-3 meses. La evaluacion funcional (pruebas de esfuerzo maximo, pruebas de marcha) permite adaptar el programa de readaptacion mejorando las capacidades oxidativas. La educacion terapeutica apunta a un cambio permanente de las costumbres nutricionales (dieta mediterranea), a estimular la actividad fisica, la abstinencia de tabaco y la observancia farmacologica, sin olvidar el patron psicologico y las condiciones socioeconomicas de cada paciente. Esta rehabilitacion se indica sobre todo cuando la expresion clinica de la claudicacion arterial se agrava, los factores de riesgo no estan controlados y existe un peligro de desinsercion sociolaboral. Puede servir como prueba terapeutica de las lesiones popliteas antes de una revascularizacion o completar este tratamiento invasivo en caso de necesidad. Representa una accion terapeutica intensiva que se justifica ante una enfermedad grave por su mortalidad cardiaca, vascular y cerebrovascular, y por su prevalencia creciente.

SummaryCardiovascular disease, such as atherosclerosis, is the main cause of mortality in developed countries. Most atherosclerosis risk factors have been identified and are treated, improving patient cardiovascular status and reducing mortality, but some remain unknown. Periodontal disease is generally defined as inflammatory disease initiated by accumulation of dental bacterial plaque, leading to the destruction of tissues that support the teeth. Severe forms have a high prevalence (15% of the population) and are associated with the presence of virulent pathogens such as Porphyromonas gingivalis. Epidemiological studies have shown that severe periodontal disease negatively influences cardiovascular status. The aim of this paper was to present a synthesis of the most recent biological data related to the link between periodontal and cardiovascular disease. The potential biological mechanisms involved in these two inflammatory diseases (bacteriological theory, inflammatory theory, immune theory) were developed. According to the observed positive effects of periodontal treatment on systemic conditions, the benefit of a reinforced collaboration between dentists and cardiologists was discussed, especially for patients at risk for cardiovascular disease.

The role of cathodic cover opening ratio on water management was investigated for micro air-breathing polymer electrolyte membrane fuel cells (PEMFCs). The results demonstrate the possibility to manage water content in micro-PEMFC using cover opening ratio variation. By measuring the internal resistance of a cell in various cover configurations (0.33 Ω cm 2 to 4.0 Ω cm 2 ), the influence of cover opening ratio on water management was shown. Indeed, for a cell situated in a 10% relative humidity atmosphere and operated at 0.5 V, the addition of a 5% opening ratio cover allowed to reach similar current densities (270 mA cm −2 ) to those recorded for the same potential at 70% relative humidity without cover. Although the starting current density for a cell operated at 60 °C without gas humidification was extremely low (15 mA cm −2 ), the total closure of the cover allowed to maintain the water produced and accumulated by the cell at the cathode, and current density of 800 mA cm −2 were reached after height minutes of operation. The influence of the opening ratio on back-diffused water was also evaluated and the maximum of back-diffused water was observed for a cell operated with a 5% cover opening ratio and represented 33% of the total water product at 150 mA cm −2 . A new method of anodic water evacuation, which does not increase the cell volume and which does not require any control tool was carried out and experimentally evaluated.

L’activite physique (AP) augmente les capacites physiques au cours des maladies cardiovasculaires par amelioration de la perfusion et du metabolisme oxydatif musculaire avec une meilleure adaptation du debit cardiaque au cours de l’effort. Elle intervient aux differents stades de la formation de la plaque d’atherome pour la prevenir, la stabiliser et en limiter les complications. Les mecanismes sont multiples : action sur la dysfonction endotheliale, sur l’hyperadrenergie, sur l’insulinoresistance, sur l’activation de la renine, sur l’inflammation et sur les troubles de la coagulation. L’AP participe egalement au controle des facteurs de risque (diabete, hypertension arterielle, dyslipidemies, surcharge ponderale, depression). Les recommandations sont de pratiquer une AP globale moderee 30 minutes par jour, 5 jours par semaine, associee a un renforcement musculaire contre resistance deux fois par semaine. Le resultat est un gain, en moyenne, de 30 % sur la mortalite.

International audience; We demonstrate the use of a grazing angle objective attachment to carry out in situ far infrared micro-spectroelectrochemistry at a copper electrode on a nano-scale. A thin-layer spectrochemical cell made out of Teflon was used, fitted with a 20-μm thick Mylar window; the working electrode was 500 μm in diameter. Measurements were carried out in 0.1 M NaOH solution as a function of applied potential between –1.4 and 0 V vs a Hg/Hg2SO4 reference electrode. Spectra were obtained with excellent signal to noise ratio for the surface oxide film, formed on copper electrochemically with less than 1 nL of active solution volume. The surface film at 0 V was about 130 nm thick and consisted mainly of CuO, with possibly some Cu(OH)2 also present. This interpretation is consistent with previous works and thermodynamic calculations. The technique should be useful in other investigations and the further development of electrochemical surface science.

Background We aimed to investigate the determinants and outcomes of multiple complex lesions (MCLs) on coronary angiography in patients with an acute myocardial infarction. Methods One thousand one hundred fifty-two consecutive nonselected myocardial infarction patients who underwent coronary angiography within 24 hours after admission were analyzed. A complex lesion was defined by the presence of thrombus, ulceration, irregular plaque, and flow impairment. Patients with ≤1 complex lesion were considered with single complex lesion (SCL), and patients with >1 complex lesions with MCLs. Results Multiple complex lesions were identified in 360 patients (31%). Patients from the MCL group were older and had a higher rate of cardiovascular risk factors but were less likely to be smokers when compared with the SCL group. Patients with MCLs were more likely to have altered left ventricular ejection fraction and multivessel disease and showed a trend toward an increased median time delay to revascularization (360 vs 285 minutes; P = .070). Moreover, the C-reactive protein (CRP) plasma levels increased with the number of CLs. By multivariate analysis, multivessel disease and CRP level were associated with the presence of MCLs. When compared with the SCL group, patients with MCLs had a higher risk of inhospital cardiogenic shock (18% vs 11%; P = .005) and 30-day mortality (11% vs 6%; P = .002). At 1-year follow-up, the presence of MCLs was an independent predictive factor of death. Conclusions This study shows that the presence of MCLs is associated with worse outcomes and that risk factors such as CRP are able to identify patients at a high risk for MCLs.

Fuel cells involve electrochemical reactions often catalysed by platinum whose surface has to be maximized. In this paper, platinum nano-particles are deposited onto graphite by a potentiostatic reduction of a dilute 1.0 mM solution of hexachloroplatinate acid. Some samples are pre-treated by highly dissociated oxygen plasma and exhibit an increase of their specific surface compared to the untreated ones. The gain factor on specific surface reaches 3.6 and even 4.4 when the plasma treatment is coupled with the impregnation technique. Surface functionalization made by the plasma treatment lead to denser deposits thanks to an organized nucleation and growth of platinum nuclei. XPS analyses suggest the existence of C–O bonds in the platinum clusters. Although the testing conditions were not optimized, we have measured the performances of a microfuel cell made with the optimized catalyst. The Scharifker and Hills electrocrystallisation model was used to fit the current transients. Untreated samples transients were correctly fitted by the model whereas plasma treated samples transients did not have the requested shape for this model. Hence, nucleation mechanism was determined and confirmed by observation on untreated samples only. The calculated value of the diffusion coefficient of the Pt(IV) anion PtCl 6 2− determined by the Cottrell theory was close to the literature, i.e. 2.6 ± 0.6 × 10 −6 cm 2 s −1 .

An infrared microscope equipped with a 64 × 64 pixel focal plane array detector was tested at the infrared beamline of the ANKA synchrotron facility. In contrast to expectations, it was found that the synchrotron beam could illuminate a usefully large area of the array detector while still delivering many times the intensity of illumination with a standard thermal source. The detector delivered excellent signal/noise ratio with a spatial resolution that would be perfectly adequate for many experiments. We conclude that synchrotron infrared microscopy beamlines should be equipped with focal plane array detectors in order to maintain their advantage with respect to similarly equipped benchtop instrumentation.

We report a case of deliberate ingestion of 12.5 g chloral hydrate in a 25-year-old psychiatric patient. Coma and life-threatening ventricular dysrhythmias were observed soon after ingestion. Repeated electrocardiographic examination was consistent with ischemic changes appearing on day 3. They were associated with segmental abnormal left ventricular wall motion by echocardiography. A coronary angiogram was performed and was normal. Toxic metabolites of chloral hydrate, trichloroethanol and trichloroacetic acid were found in the urine until day 7. This case illustrates that with halogenated aliphatic hydrocarbons, sustained changes in cardiac contractility may occur in addition to early life-threatening ventricular dysrhythmias.

Une approche de la chimie de la fracture dans des verres d'oxynitrures. Dans cette etude, nous comparons les valeurs experimentales et calculees du module elastique E d'un certain nombre de verres de SiAlON. Les valeurs de E, calculees a partir des parametres physicochimiques des phases cristallines sont en excellent accord avec les valeurs experimentales en tenant compte de la cristallochimie des oxynitrures. Le resultat final est la possibilite de proposer une approche de la structure des verres en choisissant des sous-diagrammes ternaires inclus dans le diagramme de phase total des systemes consideres.

The Cassagnau locality (Marignac-Laspeyres, Haute-Garonne department) has yielded the richest vertebrate assemblage of Late Maastrichtian age in western Europe. Numerous bones can be referred to various fishes, amphibians, chelonians, squamates, crocodiles, dinosaurs and birds, some of which constitute the first Late Maastrichtian occurrences in Europe (a large varanoid lizard, a longirostrine crocodile, an enantiornithine bird) or in Southern France (a titanosaurid dinosaur). The latter discovery shows that at least five dinosaur families were represented in the Late Maastrichtian of western Europe. As for other localities of the French Petites Pyrenees, the age of the Cassagnau locality can be directly constrained by biostratigraphical and biochronological evidence based on associated marine and continental microfauna and microflora; therefore, the assemblages from these localities can be considered as reference assemblages for the continental Late Maastrichtian localities of Southern Europe, the age of which has been much disputed.

A nearly complete turtle shell from the Upper Maastrichtian (Upper Cretaceous) of southern France is described as belonging to a new species of Elochelys , E. convenarum sp. nov. (Pleurodira: Pelomedusoides: Bothremydidae). It differs from E. perfecta Nopcsa, 1931 from the Campanian of the Fuveau Basin, southern France, mainly by its larger size, the presence of a suprapygal, the shape of the vertebral scutes and the wide posterior part of the intergular scute. This is the most complete turtle specimen and the first record of Elochelys from the Upper Maastrichtian of southern France, which indicates that the non-marine bothremydids persisted well into the latest Cretaceous in this region.

Carbon (C) and associated nutrient budgets related to land use in agro-ecosystems in West African savannas (WAS) are a matter of both local (sustainability of farming systems) and global (C balance) concern. In a mixed-farming system in southern Senegal, patterns of C, nitrogen (N) and phosphorus (P) allocation in the plant–soil system (down to a 40 cm soil depth) were compared at harvest in 14 plots, six being under semi-permanent cultivation with groundnut (Arachis hypogaea L.), others being under continuous cultivation with millet (Pennisetum glaucum L.), maize (Zea mays L.) or rice (Oryza sativa L.). Carbon stored in the plant–soil system amounted to 25.0, 27.4, 34.9 and 71.9 t per ha, respectively, in groundnut, millet, maize and rice fields. Ninety percent of C and P (total in plant Pt, available P in soil (POD)) and 95% of N of the whole ecosystem were stored in the soil. The high C and nutrient amounts found in rice plots were attributed to the clayey texture of the soil and to seasonal flooding. The lower values for C, N and POD found in soils in the bush ring (groundnut crops) compared to those of the compound ring (millet and maize crops) stemmed from land management. Higher values for C, N and POD in soils in the compound ring were maintained under continuous cultivation thanks to higher organic and nutrient inputs originating from crop residue recycling, manuring and, in the maize plots, spreading of household wastes. In the compound ring, the amount of C stored seemed to depend as much on the amount of C input as on the chemical richness of organic inflow. The effect of land management (bush versus compound ring) on soil properties was generally restricted to the 0–20 cm layer (except for P, cations and pH), and the better soil status in the compound ring was linked to nutrient depletion of the bush ring. From the perspective of global change, the estimated potential of the WAS for C sequestration under continuous cultivation was found to be low. From a methodological point of view, soil carbon status may be considered as a relevant indicator for the fertility of agro-ecosystems in the WAS belt, provided that its biotic components are included, and that both the quality and dynamics of soil organic matter (assessment of seasonal variations, and C flows) and soil texture are characterised.

New oxynitride apatites Ln 10 Si 6 O 24 N 2 and the mixed compounds Ln 1 10−x Ln 2 x (Si 6 O 22 N 2 )O 2 , with Ln = La, Ce, Nd, Sm, Gd, were synthesized and investigated. It was shown that the oxidation of the mixed Ln 1 10−x Ln 2 x (Si 6 O 22 N 2 )O 2 leads to the corresponding oxygenated apatites.

A new Late Maastrichtian locality from the Petites-Pyrenees has yielded an important vertebrate fauna. It includes Chondrichthyes (undetermined neoselachian), Osteichthyes (Lepisosteidae, Phyllodontinae, Sparidae?), Chelonia (Pleurodira), Crocodylia, and Dinosauria (Theropoda, Hadrosauridae, Nodosauridae). It is the first mention of a Cretaceous phyllodontine and the first mention of an ankylosaur in the French Late Maastrichtian. Lestaillats is the richest Late Maastrichtian locality in southern France because of the occurrence of both a microfauna and macrovertebrates. It offers new perspectives for the knowledge of the diversity and the evolution of the European vertebrate assemblages in the Latest Cretaceous.

Solid amorphous aluminophosphate oxynitride (AlPON) catalysts with a nitrogen content ranging from 0% up to 20% N (w/w) have been obtained by reaction between AlPO4 and NH3 at 800°C. Samples are analysed by X-ray photoelectron (XPS) and diffuse reflectance Fourier transform infrared (DRIFTS) spectroscopies, mass spectrometry (MS) and thermogravimetry (TG). Similar to that of AlPO4, AlPON local structure is pictured as a network of PO4 and AlO4 tetrahedra in which nitrogen preferentially replaces oxygen bonded to phosphorous, although some contribution from Al–N bonds in an AlON phase is also proposed. Nitridation stages yielding [PO3N] and [PO2N2] building units are characterised below 7.2% N and above 11% N (w/w), respectively. Also terminal –PNH2 groups are detected from early nitridation stages. Freshly prepared AlPON catalysts readily undergo hydration (10–15% by weight) and hydrolysis at atmospheric conditions. Hydration is more intense on low nitrogen containing samples and sharply decreases above 7.2% N (w/w). Ammonia is the product of both surface hydrolysis and bulk decomposition. Hydrolysis is almost independent on nitrogen content while bulk decomposition grows parallel to nitrogen percentage. Bulk decomposition below 500°C is more intense than hydrolysis and always involves terminal –PNH2 reaction either as a condensation around 230–240°C or through a reaction with water around 320–340°C. Condensation depends on –PNH2 coverage and is the preferred decomposition mechanism in high nitrogen containing AlPON.

The galloaluminophosphate oxynitrides 'AlGaPON' are phosphates in which oxygen is substituted by nitrogen, by temperature-programmed activation under ammonia. By varying the time of nitridation at 750 degrees C, Sour oxynitrides with variable nitrogen contents were obtained. They were studied by X-ray photoelectron spectroscopy and compared to the oxide precursor. Care was taken to demonstrate that with the Mg anode Ga Auger and photoelectric peak superposition did not prevent a quantitative approach of the 'AlGaPON' surface composition. This study shows that the oxygen/nitrogen substitution occurs preferentially around phosphorous and gallium atoms rather than around aluminium atoms. The good con elation between surface and bulk nitrogen content suggests a homogeneous nitridation. (C) 1998 Elsevier Science Limited. All rights reserved.

The influence of nitridation temperature on aluminovanadate catalyst synthesized by coprecipitation has been studied by XPS. This work presents the change in the vanadium environment (from the emission V2p(3/2)) and the evolution of the nitrogen multi-components signal (from the emission N1s). The results show that vanadium is present in the oxynitride in two forms: a reduced oxidation state VOx and a nitride V3+ species and that nitride nitrogen appears from 773 K.

A new family of nitrided phosphates, the oxynitrides (Ga,Al)PON, have been prepared by nitridation under ammonia flow in the 500-1000 degrees C temperature range of galloaluminophosphates obtained by sol-gel route. These (Ga,Al)PON oxynitrides, in which the P/(Ga + Al) atomic ratio and the nitrogen content can vary both, are amorphous powders characterized by high specific surface areas up to 300 m(2) g(-1). These new materials have been tested as supported platinum catalysts in the isobutane dehydrogenation and compared to other catalysts: The Pt/(Ga,Al)PON catalysts present the highest conversion and selectivity rates in isobutene. (C) 1997 Elsevier Science S.A.

A new family of phosphate oxynitrides was prepared by nitridation of an amorphous zirconophosphate precursor under ammonia flow. The oxygen substitution by nitrogen modified the acid-base properties of the zirconophosphate oxynitrides obtained. Surface acidity decreased sharply when bulk nitrogen content increased while basic properties as measured by SO2 adsorption calorimetry greatly depended on the O/N ratio. At 50 degrees C, the Knoevenagel condensation of benzaldehyde with malononitrile in toluene brings an 80% of conversion after 5 h. (C) 1997 Academic Press.

Non-isothermal kinetic parameters of devitrification for two glasses in the MgYSiAlON system were determined by differential thermal analysis. The substitution of oxygen by nitrogen in the anionic network, the cationic one remaining the same, results in a 80 kJ/mol increase of the apparent crystallization activation energy. Furthermore, the determination of the Avrami exponent, whose value is close to 1.5 for each glass, corresponds to a crystal growth probably controlled by a diffusion process.

Glass samples with the formular composition: M II 0.37 Si 0.53 A 0.10 O 1.58 − 3x 2 N x′ (M II = Mg, Ca or Ba) and M I 0.46 Si 0.46 Al 0.08 O 1.27 − 3x 2 N x (M I = Li) have been studied by infra-red absorption spectroscopy. The nitrogen-free alkaline-earth glass structure is built up with SiO 4 and AlO 4 linked units as in the metasilicate glasses. The M II cations are network modifiers, except Mg, which participate in the formative network inducing a certain part of the A 3+ cations in six-fold co-ordination which play the role of network modifiers. The lithium glass presents a silicate layer structure formed with (Si 2 O 5 ) − units and Al 3+ ions in four and/or five-fold co-ordination; the Li + cations are located between the layers. The presence of nitrogen leads to very high cross-linkage of aluminosilicate chain or layer. The M II cations are inserted into increasingly large sites (Mg- to Ba- glasses). The structural change could be correlated with the physical properties: the network rigidity increases from Ba- to Mg- glasses and with the amount of nitrogen, and the disorder was emphasized with an increasing amount of nitrogen, but especially from Mg- to Ba- glasses. These effects are less perceptible for the lithium glasses with a layer structure.

The present work is devoted to the study of the reinforcement and flow behavior of oxynitride glass matrix composites. The main objective is to combine both good reinforcement and suitability to viscoplastic forming techniques. SiC paniculate composites were synthesized with various volume fractions (up to 47 vol%) and particle sizes (from 0.5 to 150 μm. A remarkable increase of the mechanical properties is observed with increasing SiC volume fraction and decreasing particle size. The viscoplastic forming ability of the composite was then evaluated by means of creep measurements. The forming ability is found to decrease with increasing volume fraction and decreasing particle size. The rheology was also studied with relaxation tests. In this case, the kinetic is significantly higher for the glass than for the composite, consistant with the creep results.

TGA of particular oxynitrides shows an unexpected intermediate phase between starting oxynitride and final oxide. Transition between this intermediate phase and the oxide step, studied by high resolution mass spectrometry, reveals that this phenomenon can be ascribed to a nitrogen retention. We deduce the general formulation M n+ O n 2 N x . Particular properties of those phases are: low density, structure type analogous to the one of their oxynitride precursor and a nitrogen binding energy, measured by XPS, near 403 eV. By comparison to the binding energy range of organometallic dinitrogen complexes, we assume the presence of M-NN-M entities included in an oxide lattice with cationic defect structure.

The very first results of isobutane dehydrogenation over metal-supported mixed metallophosphate oxynitrides (AlMPON)-P-III (M-III = Ga, Cr) are presented. Catalytic tests show that the substitution of oxygen by nitrogen in the anionic network involves the appearance of new and more active sites. The substitution of a part of aluminium by gallium in oxynitride compounds increases significantly the activity while chromium does not modify to a great extent the conversion of isobutane. (C) 1997 Elsevier Science Limited.

A new family of phosphate oxynitrides can be prepared by nitridation of X-ray amorphous zirconophosphate precursors under ammonia flow. By varying both nitridation time and temperature, ZrPON oxynitrides with different wt% nitrogen content were obtained. Acid-base characterizations have shown that the substitution of nitrogen for oxygen modifies their surface properties. It has thus been evidenced that the surface acidity sharply decreases with bulk nitrogen enrichment. The condensation rate in the Knoevenagel reaction also heavily depends on O/N ratio. (C) 1997 Elsevier Science Limited.

Aluminophosphate oxynitride (AlPON) stability is studied by dispersing the solid in pure water and analysing the product by X-ray photoelectron spectroscopy (XPS), diffuse reflectance infra-red spectra (DRIFTS), thermogravimetry (TG) and X-ray absorption near edge structure (XANES). The presence of phosphate ions and the absence of A13+ cations in the aqueous phase indicates that no dissolution but real hydrolysis of AlPON occurs. Upon hydrolysis, AlPON loses a quite significant amount of P and N from surface. The result is a nitrogenimpoverished surface phase in which aluminum keeps its original first co-ordination sphere. This new surface phase may be ascribed to either AlPO or AlPON with a lower nitrogen content. A third possibility, phosphorous oxynitride (PON), may not be discarded due to the similarity between its PN ratio and that of hydrolysed AlPON.

The presence of nitrogen as N3− in anionic network gives the phosphorus oxynitride glass medium a reducing character which has been used to obtain precipitates of metallic silver and copper particles from the corresponding oxides. In the case of Ag2O, the reduction phenomenon can be characterized by the temperature of reduction (Tr) which is not directly related to the Tg value.

The influence of the time and temperature of nitridation of aluminium vanadate oxide precursor prepared by the co-precipitation method is presented. The surface properties of one VAlON containing 6.4 wt% of nitrogen are evaluated using two catalytic tests: the Knoevenagel condensation and the 1-butanol dehydrogenation/dehydration. This provides evidence that the substitution of oxygen by nitrogen induces basic catalytic properties.

After optimization of the processing route, the mechanical properties of the composites were evaluated with varying particle sizes and volume fractions of reinforcement. The best dispersion of the particles in the composite was obtained by using attrition milling followed by spray-drying; nevertheless, ball-milling led to satisfactory results for particle sizes higher than 3 μm. Elastic moduli, hardness and fracture toughness increase with the volume fraction of SiC. Fracture strength increases with both decreasing particle size and increasing volume fraction to reach 400 MPa for a glass matrix composite containing 47 vol% of SiC with 1 μm average panicle size. A further improvement is achieved by crystallizing the matrix.

A novel diffuse reflectance infrared spectroscopy (DRIFTS) chamber, specially designed for in situ and simultaneous infrared and conductance analysis of sensors, is described in this paper. The capabilities of this new tool are shown through the study of the reversible behaviour versus temperature of a CdGeON sensor under N 2 and synthetic-air atmospheres. The conductance of the sensor is directly related to the presence of DRIFTS bands at 810, 780 and 580 cm −1 assigned to oxygenated species directly bonded to single Ge atoms. These species are eliminated or restored in the solid network upon heating under N 2 or synthetic air, respectively. From the analysis of the resistance-temperature Arrhenius-type relationships, the influence of the atmosphere on the conduction mechanism is discussed.

Novel basic catalysts with high specific surface areas have been synthesized by activation under ammonia of an aluminophosphate oxide precursor. The nitrogen content as well as the acid-base properties depend on both time and temperature of nitridation. The conversion and reaction rate in Knoevenagel condensation are related to the nitrogen content.

Resume Sur la base de l'etude structurale de Na 3 AlP 3 O 9 N, deux series isotypes de phosphates azotes, les oxynitrures M I 3 M III P 3 O 9 N( M I = Na, K; M III = Al, Ga, In, Ti, V, Cr, Mn, Fe) et M I 2 M II 2 P 3 O 9 N ( M I = Na; M II = Mg, Mn, Fe, Co), ont ete prepares et caracterises. Plusieurs methodes permettent d'acceder a ces composes par des reactions de type gaz–solide ou solide–solide, dans l'intervalle 600–800°C. Ils cristallisent dans le systeme cubique avec un parametre a compris entre 9,2 et 10 A selon la paire cationique envisagee. From the results of the crystal structure determination of Na 3 AlP 3 O 9 N two isotypic series of nitridophosphates have been characterized with the general formulations M I 3 M III P 3 O 9 N( M I = Na, K; M III = Al, Ga, In, Ti, V, Cr, Mn, Fe) and M I 2 M II 2 P 3 O 9 N ( M I = Na, M II = Mg, Mn, Fe, Co). The preparation methods involve gas–solid or solid–solid reactions in the 600–800°C temperature range. All the oxynitrides are cubic with a parameter value between 9.2 and 10 A depending on the M I / M III or M I / M II cationic couple.

Fine physicochemical characterization has allowed proposing of a mechanism for the nitridation pathway of a polyborosiloxane polymer into a new ceramic material in the SiBON system. A polyborosiloxane, a polymer consisting of Si-O-B linkages, was synthesized by the condensation reaction between tetrachlorosilane SiCl4 and boric acid B(OH)(3). The polymer was then thermally nitridated under flowing ammonia into an oxynitride of boron and silicon. This conversion was observed using various structural techniques: chemical analysis, X-ray diffraction, infrared spectroscopy and X-ray photoelectron spectroscopy. The nitridation process can be divided in two main stages: (i) between 400 and 800 degrees C, B-N bonds are formed by B-O bond cleavage; (ii) above 1000 degrees C, Si-N bonds are formed by Si-O bond cleavage, The oxynitride remains amorphous even at 1300 degrees C. Pyrolysis up to 1700 degrees C led to a partial crystallization of hexagonal boron nitride.

A new oxynitride phase, Cd2−xGeO4−x−3yN2y, with 0.9 ≤ x ≤ 1.5 and 0.3 ≤ y ≤ 0.7 has been prepared by reaction of gaseous ammonia on a “CdGeO” amorphous phase. Its composition depends on the synthesis conditions and more particularly on the starting ratio Cd/Ge. The amorphous precursor is obtained by coprecipitation of cadmium and germanium oxides and gives after heating in air the crystallized double oxide Cd2GeO4 with or without the CdO oxide phase, depending on the initial Cd/Ge ratio. The oxynitrides obtained after nitridation have been characterized by chemical analysis and X-ray diffraction. They present a tetrahedral structure derived from the wurtzite type with orthorhombic symmetry. The lattice parameters are 5.60 ≤ a ≤ 5.75 A, 6.80 ≤ b ≤ 6.85 A, and c ≈ 5.39 A. Electrical properties have been investigated and reveal that CdXGeOYNZ-based thick films can be used as gas sensors.

Boric acid B(OH)(3) has been thermally nitrided under flowing ammonia into a boron oxynitride. This reaction has been followed using various structural techniques: X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), X-ray diffraction and chemical analyses. Reaction of boric acid with ammonia began at 155 degrees C. The weight percent of nitrogen increases with the temperature of the pyrolysis process. Formation of B-N bonds is observed at 400 degrees C by infrared spectroscopy. Two boron species are observed by XPS and identified as boron linked mostly to oxygen atoms and as boron linked mostly to nitrogen atoms, denoted BOx and BNx, respectively. The intensity of the BNx signal increases with the pyrolysis temperature.

Infrared reflectivity spectra of the series M 0.37 Si 0.53 Al 0.10 O 1.58−3χ/2 N χ with M  Mg, Ca and Ba and χ varying between 0 and 0.09 are reported. The far-infrared vibrational frequency of the M cation mainly depends on cationic mass. In the case of magnesium, the vibrational frequency is also sensitive to the coordination implying the glass-former (tetrahedral) or glass-modifier (likely octahedral). The anionic effective charge measured from the Coulombic contribution to the infrared reflection bands is smaller in nitrogenated glasses than in oxide glasses, showing an increased average bond hybrization, consistent with hardening of the structure indicated by macroscopic properties.