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Sustainable development is the way to ensure the Human progress within the bounds of the ecological possible. In this context thermoelectric systems can play an important role. However, the price of most high-performance thermoelectric devices is high, mainly due to the use of expensive elements, which raised the interest for cheap thermoelectric materials. It is also clear that the production of competitive thermoelectric devices critically depends on other factors, like the manufacturing costs, and that the materials fabrication simplicity, reproducibility, and use of easy scale-up processes will also play a fundamental role.Tetrahedrites, with generic formula Cu10M2Sb4S13 (M = Cu, Mn, Fe, Co, Ni, Zn), are world spread sulfosalt minerals that crystallize in the cubic Cu12Sb4S13-type structure. They are environment friendly materials mainly formed by non-expensive elements. Recently, mineral based and synthetic tetrahedrites were considered as promising thermoelectric materials, with zT ~ 1 at T ~ 700 K. Though, tetrahedrite melts incongruently, the preparation of appropriate tetrahedrite samples usually requiring long-term annealing procedures. Here we present a set of systematic studies on the use of tetrahedrites as low-cost and sustainable thermoelectric materials. The raw material prices evaluation, the feasibility of rapid, scalable, cheap tetrahedrite preparation and their long term stability and resistance to oxidation under working conditions are highlighted.

A Cu 12 Sb 3.6 Bi 0.4 S 10 Se 3 glass was prepared by melt spinning and crystallized by heat treatments at selected temperatures, the total preparation procedure taking less than one day. The sample characterization by powder X-ray diffraction, scanning and transmission electron microscopy complemented with EDS indicate the formation of compact materials, with a tetrahedrite relative weight fraction higher than 90% when treated at temperatures close to the crystallization peaks (∼200° C). Selenium enters the tetrahedrite structure, while bismuth precipitates in submicron and nanosized spherical shape phases depleted in copper and enriched in antimony, sulfur and selenium (when compared with the matrix composition). The characterization of electrical transport properties (electrical resistivity and Seebeck coefficient) indicate a behavior similar to that obtained by other methods on Cu 12 Sb 4 S 13 , with a maximum power factor of ∼400 μW/K 2 m at room temperature.

Anthelmintic resistance was explored by fecal egg count reduction test in a sheep flock from the French Pyrenees at the request of the veterinary practitioner after a poor response to anthelmintics was noted. The FECRT confirmed the suspicion with a mean percentage of reduction in egg excretions of 45% (CI 95%: - 40 to 78.5) and 0% (CI95%: - 162 to 49) within the ivermectin and the benzimidazole groups respectively. Haemonchus contortus was shown to be the IVM and BZ resistant species after morphological and molecular characterizations whereas Teladorsagia circumcincta was probably resistant to BZ only. The H. contortus population was still susceptible to moxidectin, closantel and levamisole. As this sheep flock is a transhumant flock, the spread of this multiple-resistant Haemonchus contortus population to the other sheep flocks sharing the same pastures in Pyrenean Mountains is highly likely. From the knowledge of the authors, this is the first report of multi-resistance to ivermectin and benzimidazole of a Haemonchus contortus population in mainland France.

Materials based on Cu12Sb4S13 tetrahedrites have been seen in recent years as promising materials for thermoelectric applications. However, the effect of small amounts of additional elements (used to tune the electrical transport properties) on the formation of the phases was not investigated. In this work we present such study, by means of powder X-ray diffraction, scanning electron microscopy complemented with energy-dispersive spectroscopy, and differential scanning calorimetry, using the Taguchi method to design the experiments. The effect of Ni, Bi and Se (i) in the volume percentage of tetrahedrite, (ii) in the temperature at which the Class III (tetrahedrite + chalcostibite + antimony → skinnerite) reaction occurs and (iii) in the final melting temperature of Cu12−xNixSb4−yBiyS13−zSez materials rapidly cooled from 950 °C was investigated. Se was observed to have a strong positive influence on the formation of tetrahedrite, while Ni and Bi were seen to promote the decrease of its volume percentage. A decrease of the Class III reaction and final melting temperatures was also observed after the introduction of Se, with Ni inducing the increase of the reaction and the decrease of the melting temperatures and Bi having only minor effects. The analysis of the microstructures indicate that high Ni concentrations lead to the first solidification of the NiS phase, while in the other compositions the (tetrahedrite/skinnerite) phase or mixtures of phases is first formed.

Copper nanopowders were sintered using Spark Plasma Sintering (SPS). Special attention was paid to the presence of natural surface oxide and reductive thermal treatments under H 2 atmosphere were carried out to remove it. The sintering mechanisms were investigated by the means of disrupted experiments at various temperatures to reach different shrinkage rates. Optimized experiments were also carried out to reach a maximum densification. The samples were characterized and compared using density measurement, X-ray diffraction, mechanical tests (tension and compression) and analysis of the fracture surfaces with scanning electron microscope. On the one hand, it results that during the SPS treatment, the raw powder undergoes a series of oxide transformations from CuO to Cu 2 O. On the other hand, reductive treatment drastically decreases the sintering temperature, from 650 °C to 260 °C, to reach 90% density without grain growth. Higher mechanical strength, up to 750 MPa, also shows better consolidation.

Background Gout is due to monosodium urate (MSU) deposition in joints and soft tissues. Ultrasonography (US) and dual-energy CT (DECT) have been shown to be effective in detecting MSU deposits. Both techniques can examine tophi size. DECT is effective to identify soft-tissue MSU deposits and US can show joint deposition with the double contour (DC) sign. It is unknown if these two techniques provide the same quantification of the extent of urate deposition on a given patient. Objectives The main objective of this study is to compare the tophus size measured by US and by DECT. The secondary objective is to evaluate the correlation between the prevalence of the US DC sign and the global volume of urate deposits measured by DECT. Methods This prospective cross-sectional study included patients fulfilling the 2015 ACR/EUALR criteria for gout. Patients underwent US and DECT examinations of their knees and feet. The largest US tophi was selected as the index tophus. US examination of the DC sign was performed on the femoro-patellar joints, talo-crural joints and 1st metatarsophalangeal joints. Total volume of urate deposits of knees and feet was measured by DECT. The primary endpoint was the intra-class correlation coefficient (ICC) of the volume of the index tophus measured by US and DECT [CI 95%]. Results A total of 64 patients were included in the study, of which 35 patients presented with at least one US tophus. Patients were in average 64.5±16.3 years old, 84.4% were male, had an average ACR/EULAR score of 13.6±2.5, and disease duration was 12±14.7 years. Overall, 44 patients (68.8%) were currently taking urate lowering therapy and 22 patients (34.4%) had clinical tophi. Out of the 35 US selected largest tophi, 6 tophi were not seen in DECT. Of the tophi identified with both techniques, 21 were localized in the feet and 8 in the knees. The ICC of the tophus volume assessment by US and DECT was 0.45 [0.12–0.69]. The average volume of the largest US tophi was 2.7±6.5 cm3 and 1.5±3.3cm3 when measured by DECT. If the index tophus was localized in the knee, the ICC was 0.36 [0–0.82] and was 0.68 [0.37–0.86] if the tophus was in the foot. The Spearman correlation coefficient between the DECT urate volume and the number of joints with a positive DC sign was 0.15. Conclusions US and DECT do not provide the same assessment of tophus size. The correlation is improved when considering tophi localized in the feet. The number of joints with positive DC sign does not correlate to the volume of urate deposition in the soft tissues measured by DECT. Disclosure of Interest None declared

The La0.85Na0.15MnO3 perovskite has been synthesized in polycrystalline form using the Spark Plasma Sintering technique (SPS). The in-situ reaction proceeds in a few minutes at 800 °C under 50 MPa with the very high heating rate of 100 °C min−1. Rietveld refinement of the X-ray diffraction patterns indicates that our sample is of pure single phase rhombohedral structure ( R 3 ¯ c symmetry). Paramagnetic–ferromagnetic phase transition at TC = 310 K is observed for our studied sample. Magnetic entropy change, | Δ S M | , deduced from isothermal magnetization curves, is about 2.42 J kg K−1 in a magnetic applied field change of 5 T. Although this value is modest, the magnetocaloric effect extends over a large temperature range leading to an important value of the relative cooling power (RCP). The RCP value at 5 T reaches 316.6 J kg−1. This value corresponds to about 77% of that observed in pure Gd.

Perovskite-type lanthanum manganite (LaMnO3) was synthesized from Mn2O3 and La2O3 precursor powders using the Spark Plasma Sintering technique (SPS). The in situ reaction proceeds in a few minutes at 1000 °C under 50 MPa with a very high heating rate of 100 °C/min. The Rietveld refinement of the X-ray powder diffraction shows that LaMnO3 sample crystallizes in a perovskite structure of O′-type orthorhombic symmetry with Pbnm space group. After annealing at 1000 °C in air for 10 hrs, the symmetry changes to rhombohedral with R-3c space group. For the as prepared sample, two critical temperature points in the temperature dependence of the ZFC and FC magnetization occurring at 125 K and 145 K are observed. They are suggested to be related to A-type antiferromagnetic Neel temperature and ferromagnetic short range order, respectively. The ferromagnetic component in the annealed sample increases indicating the expected variation in the concentration of Mn3+ and Mn4+ ions, which was attributed to the oxygen stoichiometry effects.

We had observed earlier that in the quaternary borocarbide magnetic superconductor TmNi2B2C (T-c = 11K, T-N = 1.5 K) quasistatic magnetic correlations persist well above TN (up to similar to 20 K), which is rather unusual. To further probe the nature of its spin state, we used magnetically oriented powder samples of TmNi2B2C and the mu-SR technique. We observe that the quasistatic internal held has a well defined direction. The spontaneous muon precession signal has three times the amplitude when the c-axis alignment is perpendicular to the initial muon beam polarization than when parallel. The transverse configuration enhances the oscillatory signal. This has enabled us to show that the quasistatic magnetic correlations persist even up to 50 K. Furthermore, we find a peak around 7 G in the field dependence of the longitudinal relaxation, which we attribute to the presence of a level crossing resonance arising from quadrupole levels of the boron nuclei. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

International audience; Nanostructured thermoelectric materials generally exhibit enhanced properties. PbTe-CoSb3 thermoelectric composites (0-8 wt% of PbTe) have been successfully prepared by freeze-drying nanoparticles of PbTe (6 nm in diameter, synthesized by laser fragmentation of micron-sized particles in water) with micron-sized skutterudite CoSb3 powders (around 5 µm in diameter, synthesized by powder metallurgy), followed by spark plasma sintering. X-ray diffraction analyses and scanning electron microscopy observations have been performed. Microstructures reveal an agglomeration of the PbTe particles at the grain boundaries of CoSb3. Electrical resistivity, thermopower, and thermal conductivity measurements have been performed in the 300-800 K temperature range. The composites exhibit n-type conduction whereas the reference CoSb3 skutterudite is p-type. This change of conduction mode is attributed to substitution of Sb for a minute amount of Te in the composites. The influence of both PbTe nanoparticules and Te on the thermoelectric properties is discussed in detail.

LaMnO 3 oxide was successfully synthesized from La(OH) 3 and Mn 2 O 3 precursors (molar ratio La/Mn = 0.6) using the spark plasma sintering technique (SPS). The in-situ reaction proceeds in a few minutes at 900 °C under 50 MPa with the very high heating rate of 100 °C/min. LaMnO 3 powder was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and magnetic measurements. The Rietveld refinement of the X-ray powder diffraction shows that LaMnO 3 sample crystallizes in a perovskite structure O′-type orthorhombic symmetry with Pbnm space group. Our sample undergoes an A-type antiferromagnetic order with Neel temperature equal to 138 K. The magnetic susceptibility shows the Curie–Weiss behavior between 170 and 320 K with the effective magnetic moment μ eff = 4.78 μ B /f.u and the Curie constant θ P = − 20 K (antiferromagentic sign).

International audience; The sintering of the 80GeSe2-20Ga2Se3 chalcogenide glass composition as well as the preparation of the corresponding glass-ceramics has been investigated using pulsed current electrical sintering also known as spark plasma sintering. Amorphous powder has been synthesized by mechanical alloying. Due to the electrical insulating property of this glass composition, powder is heated mostly through the heating of the graphite die. It was found that densification of glass powder occurs through a viscous flow mechanism prior to devitrification. A model has been successfully applied to determine the viscosity and activation energy of the glass. This model has been confirmed by ball penetration technique to determine the glass sample viscosity.

An original and rapid way to build efficient thermo-generator in one step based on n-type and p-type (Bi,Sb) 2 (Te,Se) 3 nano-materials embedded in a polymer matrix is described. n-Type and p-type nano-powders are obtained through a mechanical alloying process leading to particle size of about 50 nm. The flexible thermo-generator is assembled in one step by Pulsed Current Electrical Sintering (PECS) also known as Spark Plasma Sintering (SPS) from a stacking of: (1) p-type powder, (2) special design of an electrical insulating polymer matrix and (3) n-type powder. After polishing the two sides of the thermo-generators in order to reveal series of n-type and p-type thermo-elements, electrical connections of these plots are made. Due to the fast sintering treatment, the nanostructure of thermo-elements is conserved. The full thermoelectric characterizations of such thermo-generator have been investigated leading to a generated output voltage of 51 mV for 17 thermocouples (Δ T ∼ 14 °C).

Nanostructured Pb0.90Ba0.10Zr0.40Ti0.60O3 dense ceramics presenting an average grain size of 62 ± 5 nm was prepared by the polymeric precursor method and using the spark plasma sintering technique. The dielectric permittivity curves versus temperature exhibit broad anomaly, indicative of a diffuse phase transition. This result can be explained by the spread of Curie temperatures which are expected to depend on the degree of tetragonality related to the grain size distribution. A pronounced decrease in the maximum of the dielectric permittivity value is attributed to the existence of a large amount of grain boundaries which are non-ferroelectric regions.

Laser evaporation of carbon-rich uranium/carbon alloys followed by atom reactions in a solid argon matrix and trapping at 8 K gives weak infrared absorptions for CUO at 852 and 804 cm(-1). A new band at 827 cm(-1) becomes a doublet with mixed carbon 12 and 13 isotopes and exhibits the 1.0381 isotopic frequency ratio, which is appropriate for the UC diatomic molecule, and another new band at 891 cm(-1) gives a three-band mixed isotopic spectrum with the 1.0366 isotopic frequency ratio, which is characteristic of the linear CUC molecule. CASPT2 calculations with dynamical correlation find the C[triple bond]U[triple bond]C ground state as linear 3Sigma(u)+ with 1.840 A bond length and molecular orbital occupancies for an effective bond order of 2.83. Similar calculations with spin-orbit coupling show that the U[triple bond]C diatomic molecule has a quintet (Lambda = 5, Omega = 3) ground state, a similar 1.855 A bond length, and a fully developed triple bond of 2.82 effective bond order.

The Ba8ZnxGe46−x−y◻y (4 ≤ x ≤ 8, ◻ = Ge vacancy) solid solution crystallizes in the clathrate type I structure as indicated by X-ray powder diffraction and transmission electron microscopy. The fraction of vacancies (y) derived from electron probe microanalysis varies like y = 3.3 − 0.54x for 0 ≤ x ≤ 6 and y = 0 for 6 < x ≤ 8. A simplified band picture can explain how the ratio (2−)/(4−) of formal oxidation numbers of zinc and of vacancy leads to the ∼1/2 slope of the y = f(x) relation. Hall effect measurements indicate that the Ba8ZnxGe46−x−y◻y definitely deviate from the Zintl rule when 0 ≤ x < 4, weakly deviate from the the Zintl rule when 4 ≤ x ≤ 6, and fulfill the Zintl rule when 6 < x ≤ 8. Resistivity versus temperature data for 4 ≤ x ≤ 8 are in line with a “bad metal” behavior (x ∼ 4) evolving toward a degenerate semiconducting behavior (x ∼ 8). The Seebeck coefficient increases with x in agreement with the charge carrier concentration variation and reaches −67.1 μV/K in Ba7.95Zn7.83Ge38.17 which a...

We report here our results showing the occurrence of magnetic order in the intermetallic compounds NdCu2Sn2 and PrCu2Sn2. For comparison, non-magnetic analogue, LaCu2Sn2, was also prepared. X-ray diffraction (XRD) result confirms that all the three compounds form in the tetragonal CaBe2Ge2-type structure. A cusp is observed at not, vert, similar3 K in the magnetic susceptibility of NdCu2Sn2 and PrCu2Sn2, which arises due to the antiferromagnetic ordering of the magnetic moments in these two compounds. The bulk nature of magnetic order in both the compounds is confirmed from the observation of peaks in the heat capacity at the magnetic transition temperature. X-ray absorption measurements at the LIII edge show that Pr ions are in the trivalent state in PrCu2Sn2., © Elsevier

En eau de mer, lors de l'application de la protection cathodique sur un acier au carbone, un depot calco-magnesien se forme a sa surface. Ce depot est un facteur important puisqu'il renforce l'effet protecteur de la protection cathodique en jouant le role de barriere de diffusion de l'oxygene. La comprehension de la formation de ce depot et de l'influence des differents parametres physico-chimiques sur ses proprietes, est essentielle dans la recherche de l'amelioration des performances des systemes de protection cathodique. L'objectif de cette etude est de determiner le role de la concentration en matiere organique sur la formation et les proprietes de ce depot. En eau de mer artificielle, les depots calco-magnesiens formes en presence de matiere organique aux concentrations de l'ocean ouvert et cotier, presentent des caracteristiques semblables. Une concentration excessive en matiere organique, par rapport a ce qui peut etre observable, inhibe la precipitation du carbonate de calcium et de l'hydroxyde de magnesium.

Based on an analysis of the geometric crystallographic relations a general classification scheme is presented for intermetallides with four-coordinated networks isomorphous with hydrate clathrates. We prepared novel europium substituted clathrates, Eu 2-x (Sr,Ba) 6-x M y Si 46-y (M=Al, Ga), consistent with the standardized clathrate I-Ba 8 Al 16 Ge 30 type structure (space group Pm3n). Europium atoms in Ba compounds preferentially occupy the 2a position and thus form a new quaternary version of the Ba 8 Al 16 Ge 30 structure type. All clathrates studied are metals with low electrical conductivity. The negative Seebeck coefficients indicate transport processes dominated by electrons as carriers. Eu 2 Ba 6 Al 8 Si 36 and Eu 2 Ba 6 Ga 8 Si 36 exhibit long-range magnetic order below 32 and 38K of presumably ferromagnetic type. Magnetic susceptibilities indicate an Eu 2+ ground state, in fine agreement with L III absorption edge spectra.

Single crystals of the novel ternary compounds EuZn 2 Si 2 and EuZn 2 Ge 2 were grown from pure gallium, indium, or zinc metal used as a flux solvent. Crystal properties were characterized using X-ray single-crystal analyses via Gandolfi and Weissenberg film techniques and by four-circle X-ray single-crystal diffractometry. The new compounds crystallize with ternary derivative structures of BaAl 4 , i.e., EuZn 2 Si 2 with ThCr 2 Si 2 -type ( a =0.42607(2) nm, c =1.03956(5) nm, I 4/ mmm , R 1 =0.038) and EuZn 2 Ge 2 with CaBe 2 Ge 2 -type ( a =0.43095(2) nm, c =1.07926(6) nm, P 4/ nmm , R 1 =0.067). XAS and magnetic measurements on EuZn 2 Si 2 and EuZn 2 Ge 2 revealed in both compounds the presence of Eu 2+ ions carrying large magnetic moments, which order magnetically at low temperatures. The magnetic phase transition occurs at T N =16 and 7.5 K for the silicide and the germanide, respectively. In EuZn 2 Si 2 there occurs a spin reorientation at 13 K and furthermore some canting of antiferromagnetically ordered moments below about 10 K. In EuZn 2 Ge 2 a canted antiferromagnetic structure is formed just at T N .

The application of the cathodic protection, as well as the formation of the Ca, Mg deposit that results, are currently very defined but solely in marine environment exempt of bacteria, as the open ocean. The investigation in natural sea water, in presence of sulphogenic bacteria, achieved on long terms (two months) are infrequent. The calcareous deposit evolution is mainly function of different parametres : the cathodic protective potential, the application time of this one, the yield Mg/Ca of the middle, its microbial load and the organic matter presence dissolved. In artificial sea water, the deposit now presents some features known, so magnesium appears solely for very cathodic potentials, returning the pH favorable to its precipitation. As for the calcium, it can be formed down to weaker pH. However, for kinetics reasons, magnesium can appear earlier. In sea water to weak bacterial pollution, magnesium appears little for potentials cathodic since –800 mV/ECS. However, more the application time increases (until two months) more the quantity of calcium increases and cover magnesium. In sea water where the bacterial concentration (at least 108 Bacteria reducing sulphate and thiosulphate.ml-1) is important, the features of the deposit remain the same. Only the compactness and the density of the deposit are different : they increase in presence of bacteria. This survey shows that : the bacterial presence and more especially the bacteria sulfurogenes, the chemical composition of the sea water and the concentration in dissolved oxygen, are factors influencing the formation and the evolution of the deposit calcareous more or less.

It has been claimed earlier ( J. Alloys Comp. 186, 223 (1992)) that Ce 2 Ni 22 C 2.75 is ferromagnetic at room temperature. In this paper it is shown, with magnetic susceptibility and electrical resistivity measurements, that no ferromagnetic order exists in our Ce 2 Ni 22 C 2.75 sample down to 1.7 K. Moreover, the temperature dependencies of both magnetic susceptibility and electrical resistivity agree well with the existing theoretical models for intermediate valence fluctuating compounds. This agreement together with X-ray absorption spectroscopy data obtained at two fixed temperatures, 10 and 300 K, clearly give evidence for a nonintegral valence state of Ce in Ce 2 Ni 22 C 2.75 .

As part of a program monitoring the contamination of Cetaceans by heavy metals on the French Mediterranean coast, the levels of cadmium, copper, mercury, nickel, lead and zinc in nine striped dolphins (Stenella coeruleoalba), stranded dead on the beach in 1996 and 1997, have been worked out. The results obtained were compared to those of a similar study carried out in 1990 and 1991 on the same species. A significant decrease in the concentrations of copper, mercury, nickel and lead was shown, as well as a slight decrease in the concentrations of cadmium. Contamination by zinc was not lower and remain rather high. These results are most likely the consequence of the efforts made to clean up the coast, inadequat as it may be. Indeed, the metallic contents of the most contaminated dolphins still remain high and pose a toxicological problem which is discussed, with emphasis on mercury. Cetacean are reliable biological indicators and irrefutable evidence of the chronical poisoning of the sea and of the danger ...

Background. Delayed graft function (DGF) has remained an important complication after renal transplantation. The exact causes of DGF remain to be clarified, particularly the impact of retrieval conditions and preservation factors. In the present investigation, 1HNMR spectroscopy of urine was assessed in order to detect the influence of retrieval condition on renal medulla damage. Methods. The isolated perfused pig kidney (IPK) was used to assess initial renal function from multiorgan donors (MOD) or single organ donors (SOD) after in situ cold flush and 24-h cold storage (CS) preservation with two standard preservation solutions: Euro-Collins (EC) and University of Wisconsin (UW) solutions. Kidneys flushed with cold heparinized saline and immediately perfused were used as the control group. Kidneys were perfused for 90 min at 37.5°C for functional evaluation. During reperfusion, renal perfusion flow rate (PF) was measured. Glomerular filtration rate (GFR), tubular reabsorption of Na+, and lactate dehydrogenase (LDH) and N-acetyl-β- d -glucosaminidase (NAG) excretions were determined. Ischemia–reperfusion impairment was also determined by histological techniques and 1HNMR spectroscopy. Results. PF, GFR, and tubular reabsorption of Na+ were significantly decreased in experimental groups when compared to the control group but there was no significant difference between experimental SOD groups. GFR was significantly greater in UW-MOD than in EC-MOD and tubular reabsorption of Na+ was significantly greater in UW-MOD than in EC-MOD after 45 min of reperfusion. The release of LDH in the effluent and the urinary excretion of NAG were not significantly different after 24-h CS in the various experimental groups. The most relevant resonances determined by 1HNMR spectroscopy were citrate, trimethylamine-N-oxide, lactate, acetate, and amino acids. Excretion of these markers was significantly different when compared to biochemical markers. A resonance (P) detected particularly in EC-MOD after 24-h CS was identified and well correlated to renal dysfunction. Histological study showed that ultrastructural damage and mitochondrial injury were more pronounced in the EC-MOD group. Conclusion. These results show that retrieval condition influences renal medullary damage. NMR spectroscopy, which is a noninvasive and nondestructive technique, is more efficient in assessing renal damage than conventional histology and biochemical analysis.

We have investigated the nearly isotropic superconducting intermetallicRNi2−xMxB2C system (M=Pd, Pt, and Co,x=0.05–0.2) by complementary experimental techniques. For TmNi2B2C,TC=10.7 K and the antiferromagnetic (AFM) order of the Tm spins develops belowTN=1.48 K. Pt as a dopant affectsTCvery little, whereas, forM=Pd,TCis reduced to 9.9 and 9.1 K forx=0.05 and 0.1, respectively. For TmNi2B2C and TmNi1.9Pt0.1B2C, theHc1values exhibit a maximum at 3 K. While the AFM transition for TmNi2B2C atTNis clearly identified by specific heat measurements, no specific heat anomaly was observed for TmNi1.9Pd0.1B2C down to 0.8 K, indicating that Pd as a dopant drastically reducesTCandTNof the system. For ErNi2B2C,TC=10.9 K andTN=6.3 K (TC>TN). In ErNi2−xMxB2C, both Pt and Pd as dopants (x=0.2) reduceTCto ∼8 K and shiftTNto ∼11 K. ForM=Co andx=0.05TCis reduced to 4.8 K andTNincreases to 8.2 K. For higher Co concentrations (x=0.2 and 0.5), the compounds are not superconducting, andTNincreases to 10.9 and 14.8 K respectively. It appears that for ErNi2−xMxB2C (i) forx=0.2 the sameTN∼11. K is obtained regardless ofM, and that (ii) in contrast toR=Tm, all dopants studied lead to a reduction ofTCand to an increase ofTNof the Er sublattice, thusTC

The compounds Yb(Cu,Ag,Au)Sb were synthesized via high frequency melting of the elements in a closed Ta-crucible. The crystal structure of the novel phases was determined from X-ray powder Rietveld refinements. Dependent on the ratio R Yb / R (Cu,Ag,Au) different structure types were encountered: YbCuSb (ordered Ni 2 In-type, R F =0.036), YbAgSb (TiNiSi-type, R F =0.054) and YbAuSb (LiGaGe-type, R F =0.038). The results of the magnetic measurements revealed that the compounds YbCuSb and YbAgSb are temperature independent Pauli-type paramagnets whilst a small magnetic moment (≈1β B ) was observed for YbAuSb. In good agreement, X-ray absorption spectroscopy (at 10 and 300 K) confirmed for all three compounds dipositive Yb temperature independent valencies of 2.06 (M = Ag), 2.08 (Cu) and 2.14 (Au); possibly owing to small amounts (less than upo to ≈ 4%) of Yb 3+ grain boundary effects.

We have investigated Pr{sub 1.5}Ce{sub 0.5}{ital M}Sr{sub 2}Cu{sub 2}O{sub {ital z}} ({ital z}=9 or 10) materials ({ital M}=Ta, In, and Nb+Ga) by complementary experimental techniques. All materials studied are not superconducting. Magnetic susceptibility studies for {ital M}=Ta reveal one magnetic anomaly at 23 K and irreversibility phenomena at higher temperatures. The presence of 0.5{percent} {sup 57}Fe dramatically affects the positions of the anomalies, and M{umlt o}ssbauer spectroscopy studies (MS) reveal that the Cu(2) sites are magnetically ordered below {ital T}{sub {ital N}}(Cu)=130 K. This low {ital T}{sub {ital N}}(Cu) obtained is discussed. No specific heat anomaly was observed at 23 K, suggesting that the Pr sublattice does not order magnetically, and the anomalies in the susceptibility originate from the Cu moments. No anomalies in the susceptibility curves are found for {ital M}=In and Nb+Ga compounds. However, MS indicate that for the mixed compound, the Cu sites are magnetically ordered at low temperatures. The magnetic behavior of {ital M}=Ta is compared to similar systems with two anomalies for {ital M}=Nb at 11 and 52 K, and three anomalies for {ital M}=Ga at 12, 52, and 94 K. X-ray absorption spectroscopy (XAS) indicates that in all materials studied, the Pr has amore » mixed valence close to 3. The Pr valence does not change with temperature. {copyright} {ital 1996 The American Physical Society.}« less

Compounds YbTGa2 with TNi, Pd, Pt and alloys YbPd1−xAgxGa2 have been synthesized by argon high frequency melting from metal ingots in tantalum crucibles followed by homogenization annealing at 600 or 400°C respectively. From X-ray powder diffraction data. Yb{Ni.Pd,Pt}Ga2 was found to be isotypic with MgCuAl2-type, with a small solid solubility for Ag in YbPdGa2 (0 ⩽ x ⩽ 0 2). At 600°C the solid solubility of Pd in βYbAgGa2 (βYbAgGa2-type) was 0.7 ⩽ x ⩽ 1.0. The YbTGa2 (T = Ni, Pd, Pt) compounds are paramagnets, where the ytterbium adopts the 2 F 7 2 ground state. The magnetic results of the solid solution YbPd1−xAgxGa2 are characterized by an intermediate or mixed valence behavior of the ytterbium atom (Yb2+a Yb3+), whereas XAS measurements establish a mixed valence system.

Ternary compounds CeMSb2 and CeM′Bi2 have been synthesized by arc melting followed by a heat treatment at 400, 600 or 800°C for 300 h. Bismuth-containing compounds have been observed for the first time. From X-ray powder diffractometry all compounds were found to be isotypic with ZrCuSi2-type. In CeMn0.9Sb2, the manganese sublattice orders ferromagnetically at T∼130 K, and the cerium sublattice shows additional ordering at ∼20 K. CeMSb2 (M=Fe, Ni, Pd, Cu, Ag, Au, Zn) are antiferromagnets below T=12 K. In the paramagnetic regime, the cerium atom adopts the Ce- 2 F 5 2 tripositive groundstate. CeCu0.9Bi2 is also an antiferromagnet, whereas for Ce(Ag,Zn)Bi2 no magnetic order was encountered. X-Ray absorption spectroscopy shows that Ce in all compounds CeMSb2 and CeMBi2 is in the trivalent, or nearly trivalent, state.

We report here our results on a new intermetallic compound, EuAgSn. X-ray diffraction studies of the material show that it forms in the orthorhombic-type structure. Magnetic susceptibility results show that the material orders magnetically at ∼ 6.5 K. The temperature dependence of the paramagnetic susceptibility follows a Curie-Weiss behaviour with an effective moment close to that of the free Eu 2+ ion. 151 Eu and 119 Sn Mossbauer studies confirm the magnetic ordering. The 151 Eu isomer shift (∼ −11 mm/s) is consistent with the stable divalent state of Eu in this material.

We report on the intermediate valence of Ce in ${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ce}}_{\mathit{x}}$${\mathrm{Ni}}_{2}$${\mathrm{B}}_{2}$C as studied by x-ray diffraction (lattice parameters), x-ray absorption spectroscopy (XAS), and magnetic measurements for samples with x=0, 0.05, 0.1, 0.25, 0.5, and 1. The average valence 〈v〉 of Ce, as determined from XAS, is much below the saturation value 3.3 in ${\mathrm{CeNi}}_{2}$${\mathrm{B}}_{2}$C; it increases from 3.15(2) at 300 K to 3.21(2) at 10 K. Ce is in mixed valence state [〈v〉=3.18(2)] in the dilute limit (x=0.05) in which case the temperature dependence of 〈v〉 is rather weak. Cooperative effects (their presence in the stoichiometric material ${\mathrm{CeNi}}_{2}$${\mathrm{B}}_{2}$C and absence in the dilute alloy ${\mathrm{Y}}_{0.95}$${\mathrm{Ce}}_{0.05}$${\mathrm{Ni}}_{2}$${\mathrm{B}}_{2}$C) may also be responsible for this difference in the values of 〈v〉. We also report on the depression of the superconducting temperature ${\mathit{T}}_{\mathit{c}}$ induced by Ce, as studied by ac-susceptibility, in the series.

Substitutions of Cu by Ga in ${\mathrm{YbCu}}_{5}$ stabilize the hexagonal ${\mathrm{CaCu}}_{5}$ structure and cause a crossover from a divalent behavior of the Yb-ion in ${\mathrm{YbCu}}_{5}$ to an almost 3+ state of Yb in ${\mathrm{YbCu}}_{3}$${\mathrm{Ga}}_{2}$. This gain of magnetism is accompanied by a noticeable enhancement of the electronic contribution to the specific heat. External pressure transforms those compounds, exhibiting intermediate valence, to a state which is best described in terms of the Kondo lattice model.

This paper reviews the semiconducting glasses for thermoelectric applications. Several examples of tellurium-based glasses, with high Seebeck coefficients, very low thermal conductivities and tunable electrical conductivities, are presented, pointing this family of glasses as a good candidate for high-performance thermoelectric materials.

This paper presents a study of the influence of particle size on the structural and dielectric properties of Pb 0.85 La 0.15 TiO 3 (PLT15) ferroelectric ceramic samples. The samples were prepared with average grain size of 1.69 ± 0.08 μm and 146 ± 8 nm using, respectively, conventional and spark plasma sintering techniques. A decrease in the tetragonality degree as the crystallite size decreased was explained by an internal stress caused by the existence of a large amount of grain boundaries. The local structure exhibited no significant modification and the dielectric measurements showed a diffuse phase transition and a reduction in the permittivity magnitude at T m as the average grain size decreased. The nanostructured ceramic sample prepared at a relatively lower temperature and sintering time presented a dielectric constant value of approximately 2000 at room temperature.

Recently we reported superconductivity in Y-Ni-B-C system, the first known quaternary superconducting system. One of the superconducting materials reported by us had the nominal chemical composition YNi4BC0.2. We examine, in this paper, effect of replacing nickel by palladium which is an obvious and natural step for us since we believe that the d-electrons are carriers of superconductivity in these materials. Our samples with the nominal composition YPd4BC(x) (0.2 < x < 1) have a superconducting minority phase with transition onset temperature as high as 22 K. Some of the samples show another superconducting transition at approximately 10 K, indicating one more superconducting phase in this sytem. We have also investigated LuPd4BC0.2, (Lu being the end member of the rare earth series) which also shows existence of a superconducting phase with T(c) approximately 10 K.

Fukuhara et al. reported SmRuSn3 to be the first Sm-based valence-fluctuating (VF) ternary compound which also orders magnetically. We report here our results of X-ray diffraction, microprobe analysis and L(III)-edge X-ray absorption measurements. We argue that Sm ions are VF at only one crystallographic site (2a); Sm ions at the other site (6d) are in a stable trivalent state. This assignment of the valence state is consistent with our magnetic-susceptibility and specific-heat measurements.

We have observed a superconducting transition at 12 K in the system Y-Ni-B (nominal composition: YNi4B). Sharp drop in resistivity (it does not go to zero) and a diamagnetic susceptibility below 12 K clearly indicate a superconducting transition. Possibility of a magnetic phase transition at this temperature is ruled out by our specific heat measurements. Superconducting fraction of our samples, as estimated from Meissner effect measurements, is about 2%.

Introduction Les manifestations cutanees du syndrome uretro-oculo-articulaire (syndrome de Fiessinger-Leroy-Reiter) sont rares mais souvent evocatrices et specifiques. Nous rapportons le 3 e cas de la litterature ayant repondu sous infliximab. Observations Nous rapportons le cas d’un homme de 28 ans, travaillant dans la production agro-alimentaire, ayant presente un syndrome uretero-oculo-articulaire (uretrite, conjonctivite, spondylarthrites axiales et peripheriques) associe a des lesions dermatologiques. Ces dernieres etaient pustuleuses et psoriasiformes : elles siegeaient en plaques sur le dos, prenaient la forme d’une keratodermie blennorragique de Vidal et Jacquet avec l’aspect typique de clous de tapissier sur les plantes des pieds, evoquaient une acrodermatite continue d’Hallopeau aux orteils. Une atteinte muqueuse etait egalement presente avec une balanite circinee et des erosions buccales. La chronicite du tableau avait entraine une alteration de l’etat general avec un malade asthenique et amaigrit de 20 kg, ainsi qu’une impotence majeure a la marche. Le malade etait HLA B27 positif, les prelevements uretraux et la coproculture etaient negatifs, la serologie VIH egalement, la ponction articulaire sterile. Les polyarthrites resistaient aux lignes successives par AINS, sulfasalazine, corticotherapie systemique. Un traitement par doxycycline pendant 7 jours puis infliximab etait alors introduit, avec une nette efficacite sur les composantes articulaires et cutanees. Discussion Ce malade a presente la forme complete du syndrome uretro-oculo-articulaire. L’atteinte dermatologique de ce syndrome est presente dans 20 % des cas, la manifestation la plus frequente etant la balanite circinee (20 %) tandis que l’aspect classique en clous de tapissier n’est present que dans 8 % des cas. Ce syndrome s’integre dans le cadre des arthrites reactionnelles. Le micro-organisme causal n’est pas retrouve dans environ 50 % des cas. Les cas associes a un typage HLA B27 ainsi qu’a Chlamydia ont un risque plus important d’evolution chronique defavorable. Un traitement antibiotique a montre son interet uniquement en cas d’uretrite causale a C. trachomatis . L’efficacite des anti-TNF alpha dans les arthrites reactionnelles n’a fait l’objet d’aucune etude de grande envergure. Cependant, lors d’une evolution chronique avec echappement aux therapeutiques habituelles (AINS, corticotherapie systemique, sulfasalazine, methotrexate), une trentaine de succes ont ete rapportes. Concernant l’atteinte dermatologique de ce syndrome, on ne recense que 2 cas traites avec succes par infliximab et 1 cas par etanercept. Voici un 4 e cas suggerant l’interet des anti-TNF alpha. Conclusion Les anti-TNF alpha semblent etre efficaces dans les arthrites reactionnelles dont le syndrome uretro-oculo-articulaire tant sur l’atteinte articulaire que cutanee, comme l’illustre notre observation. Ils sont a reserver en derniere ligne apres echec des therapeutiques habituelles.

Various structural aspects of two well-known varieties of MnO2: the pyrolusite (and its synthetic equivalent β-MnO2) and the ramsdellite are re-examined by studying the long-range order from previous X-ray diffraction results and the short-range order using EXAFS. From both, it is concluded that, in EXAFS fitting procedure, local Mn neighbors must include two Mn shells and two oxygen shells. These studies are extended to a third variety, the γ-MnO2, whose structure is supposed to be based on intergrowth domains of the two previous varieties. The two types CMD and EMD of γ-MnO2 used in commercial batteries are investigated. EXAFS is shown to be a powerful technique to define exactly structural aspects on those poorly crystallized materials.

We report here the changes in the europium valence in Eu 1−x Ln x Pd 2 Si 2 (LnLa, Y, Yb; 0 x - III absorption edge spectroscopy. On the basis of the simple unit-cell volume considerations and from the fact that the unit-cell volume of EuPd 2 Si 2 is intermediate between that of LaPd 2 Si 2 and Y(Yb)Pd 2 Si 2 , one expects the europium valence to vary in both cases as a function of x , with the variation taking place in the opposite directions in the two pseudoternaries Eu 1−x La x Pd 2 Si 2 and Eu 1−x Y(Yb) x Pd 2 Si 2 . However, we find that the valence does not change as a consequence of lanthanum substitution and increases with the addition of yttrium (ytterbium). These results are discussed in terms of the local environment of europium atoms in these systems.

Background: As a result of population growth in African-Caribbean regions of overseas France, and now immigration essentially from North and sub-Saharan Africa to mainland France, neonatal screening for sickle cell disease (SCD) has been performed in France since 1985 in Guadalupe and dependencies, as a universal test. After several pilot studies, screening was gradually extended to mainland France in 1996. Since 2000, the test has been performed at national level for all newborns defined as being “at risk” for SCD based on ethnic origin. Methods: A dry blood sample is obtained by heel stick and analysed by isoelectric focusing as a first-line method, followed by either high-performance liquid chromatography or acid agar electrophoresis for confirmation, whenever a variant haemoglobin is observed on isoelectric focusing. Results: In 2007, 28.45% of all newborns in mainland France were screened for SCD. Since 1996, a total of 3890 newborns have been found to have SCD, and they have been followed up by reference paediatricians. Conclusion: Although screening for SCD at birth in France is not universal, it appears that missed babies are relatively infrequent. Despite obvious sociological problems inherent to the at-risk population, the follow-up of SCD babies is rather successful. Due to the birth prevalence of SCD in France, especially in comparison with other common genetic diseases, screening all newborns regardless of ethnic origin is an issue that is being addressed.

We have performed XANES measurements at the Pr L III -edge (∼5950–5980 eV) in Y 0.8 Pr 0.2 Ba 2 Cu 3 O 6.95 , PrBa 2 Cu 3 O 6.94 and in PrBa 2 Cu 3− x Co x O y ( x =0.2, 0.3, 0.4, 0.5, 1.0 and y =6.99, 7.0, 7.01, 7.05, 7.29, respectively). By comparing these spectra with those of praseodymium oxides (PrO z , z =1.5, 1.71, 1.8, 1.83, 2) we derived the valence ( v ) of Pr in these compounds. In Y 0.8 Pr 0.2 Ba 2 Cu 3 O 6.95 v =3.4 (±0.1) and in PrBa 2 Cu 3 O 6.94 v =3.18 (±0.05). Upon doping with Co, v decreases progressively to v =3.0 for x ∼0.4–0.5 and remains constant for x >0.5.