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Linezolid is an antibiotic used against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus. Its primary adverse effect is haematotoxicity. The objective of this study was to analyse the risk factors for onset of thrombocytopenia in critically ill patients treated with linezolid. This was a retrospective, single-centre study of 72 patients. Platelets were measured from D0 to D20 after the start of treatment. The risk factors for thrombocytopenia were identified using a multivariate logistic regression analysis following a Monte Carlo simulation. Following ROC curve analysis, a baseline platelet count lower than 108 × 109/L and a Cmin higher than 4 mg/L, with respective odds ratios of 117 (95% CI [97-206]) and 3 (95% CI [1.5-6.2]) in the simulated population, were identified as risk factors. Among the source population patients combining these 2 factors, a significantly higher number developed thrombocytopenia (66.7% vs. 33.3%, p = 0.0042). A baseline platelet count lower than 108 × 109/L and a Cmin higher than 4 mg/L are risk factors for the onset of thrombocytopenia in critically ill patients treated with linezolid.

For a successful integration of silicon in high-capacity anodes of Li-ion batteries, its intrinsic capacity decay on cycling due to severe volume swelling should be minimized. In this work, Ni-Sn intermetallics are studied as buffering matrix during reversible lithiation of Si-based anodes. Si/Ni-Sn composites have been synthetized by mechanical milling using C and Al as process control agents. Ni3Sn4, Ni3Sn2 intermetallics and their bi-phasic mixture were used as constituents of the buffering matrix. The structure, composition and morphology of the composites have been analyzed by X-ray diffraction (XRD), 119Sn Transmission M\"ossbauer Spectroscopy (TMS) and scanning electron microscopy (SEM). They consist of ~ 150 nm Si nanoparticles embedded in a multi-phase matrix, the nanostructuration of which improves on increasing the Ni3Sn4 amount. The electrochemical properties of the composites were analyzed by galvanostatic cycling in half-cells. Best results for practical applications are found for the bi-phasic matrix Ni3Sn4-Ni3Sn2 in which Ni3Sn4 is electrochemically active while Ni3Sn2 is inactive. Low capacity loss, 0.04 %/cycle, and high coulombic efficiency, 99.6%, were obtained over 200 cycles while maintaining a high reversible capacity above 500 mAh/g at moderate regime C/5, Comment: 11 pages, 7 figures, 5 tables

One-step ball-milling method is proposed to synthesize Ni-Ti-Si composites as anode materials for Li-ion batteries. From this approach it is possible to obtain the ternary compound Ni4Ti4Si7, which is poorly crystallized and does not show significant electrochemical activity. More interesting performances have been obtained for the Si-rich composite with the chemical composition Ni0.12Ti0.12Si0.76. The specific capacity is of about 700 mAh g−1 with a coulombic efficiency of 99.8% at the 50th cycle. This composite is formed by small Si particles embedded in a matrix mainly composed of the binary phases of the Ni-Ti-Si system and Ni4Ti4Si7. The analysis of the reaction mechanism by differential capacity and in situ X-ray diffraction (XRD) indicates that Si particles react with Li to form LixSi amorphous phases while most of the intermetallic phases are electrochemically inactive. A particular attention has been devoted to the evaluation of the integral intensity of some XRD structures to determine the main trends in the formation of species during the first discharge-charge cycle. The results confirm the electrochemical inactivity of the matrix that maintains the dispersion of the Si particles and buffers the volume variations.

Glial fibrillary acidic protein (GFAP), ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1), and matrix metalloproteinase 9 (MMP-9) are potential biomarkers of traumatic brain injury (TBI) but also of secondary insults to the brain. The aim of this study was to describe the cerebral distribution of GFAP, UCH-L1, and MMP-9 in a rat model of diffuse TBI associated with standardized hypoxia-hypotension (HH). Adult male Sprague-Dawley rats were allocated to Sham (n = 10), TBI (n = 10), HH (n = 10), and TBI+HH (n = 10) groups. After 4 hours, brains were rapidly removed and immunostaining of GFAP, UCH-L1, and MMP-9 was performed. Areas of interest that have been described as particularly sensitive to hypoxic insults were analyzed. For GFAP, in the neocortex, immunostaining revealed a significant decrease in strong staining for HH and TBI+HH groups compared with TBI group ( P

Summary Background Acute acidaemia is frequently observed during critical illness. Sodium bicarbonate infusion for the treatment of severe metabolic acidaemia is a possible treatment option but remains controversial, as no studies to date have examined its effect on clinical outcomes. Therefore, we aimed to evaluate whether sodium bicarbonate infusion would improve these outcomes in critically ill patients. Methods We did a multicentre, open-label, randomised controlled, phase 3 trial. Local investigators screened eligible patients from 26 intensive care units (ICUs) in France. We included adult patients (aged ≥18 years) who were admitted within 48 h to the ICU with severe acidaemia (pH ≤7·20, PaCO2 ≤45 mm Hg, and sodium bicarbonate concentration ≤20 mmol/L) and with a total Sequential Organ Failure Assessment score of 4 or more or an arterial lactate concentration of 2 mmol/L or more. We randomly assigned patients (1:1), by stratified randomisation with minimisation via a restricted web platform, to receive either no sodium bicarbonate (control group) or 4·2% of intravenous sodium bicarbonate infusion (bicarbonate group) to maintain the arterial pH above 7·30. Our protocol recommended that the volume of each infusion should be within the range of 125–250 mL in 30 min, with a maximum of 1000 mL within 24 h after inclusion. Randomisation criteria were stratified among three prespecified strata: age, sepsis status, and the Acute Kidney Injury Network (AKIN) score. The primary outcome was a composite of death from any cause by day 28 and the presence of at least one organ failure at day 7. All analyses were done on data from the intention-to-treat population, which included all patients who underwent randomisation. This study is registered with ClinicalTrials.gov, number NCT02476253. Findings Between May 5, 2015, and May 7, 2017, we enrolled 389 patients into the intention-to-treat analysis in the overall population (194 in the control group and 195 in the bicarbonate group). The primary outcome occurred in 138 (71%) of 194 patients in the control group and 128 (66%) of 195 in the bicarbonate group (absolute difference estimate −5·5%, 95% CI −15·2 to 4·2; p=0·24). The Kaplan-Meier method estimate of the probability of survival at day 28 between the control group and bicarbonate group was not significant (46% [95% CI 40–54] vs 55% [49–63]; p=0·09. In the prespecified AKIN stratum of patients with a score of 2 or 3, the Kaplan-Meier method estimate of survival by day 28 between the control group and bicarbonate group was significant (37% [95% CI 28–48] vs 54% [45–65]; p=0·0283). Metabolic alkalosis, hypernatraemia, and hypocalcaemia were observed more frequently in the bicarbonate group than in the control group, with no life-threatening complications reported. Interpretation In patients with severe metabolic acidaemia, sodium bicarbonate had no effect on the primary composite outcome. However, sodium bicarbonate decreased the primary composite outcome and day 28 mortality in the a-priori defined stratum of patients with acute kidney injury. Funding French Ministry of Health and the Societe Francaise d'Anesthesie Reanimation.

Postoperative pain management is a clinical challenge that can be complicated by opioid-induced hyperalgesia (OIH). Kinin receptors could mediate both the acute and chronic phases of inflammation and pain. A few recent studies suggest that dynorphin A could maintain neuropathic pain by activating the bradykinin (BK) receptor. Thus, the effect of a single administration of sufentanil (a μ-opioid receptor agonist) was investigated in a model of carrageenan-induced inflammatory pain using three strains of mice, i.e., knockout mice for one kinin receptor, B1R or B2R (B1KO, B2KO), and wild-type C57/BL6J mice (WT) treated with either a B1R (R954) or a B2R antagonist (HOE140) or a KKS inhibitor (aprotinin). Pain was assessed and compared between the different groups using two behavioral tests exploring mechanical (von Frey filaments) and thermal (Hargreaves test) sensitivity. Pretreatment with sufentanil induced a sustained increase in pain sensitivity with a delayed return to baseline values characterizing an OIH in carrageenan-injected mice only. Sufentanil-induced OIH was not observed in B2KO but persisted in B1KO and was blunted by aprotinin and the B2R antagonist only. Collectively, our data indicate that the B2R receptor and BK synthesis or availability are essential peripheral steps in the mechanism leading to OIH in a pain context.

Background The cecal ligation and puncture (CLP) model, a gold standard in sepsis research, is associated with an important variability in mortality. While the number of punctures and needle size is well described in CLP animal studies, the length of cecal ligation is often not. The relationship between cecal ligation and survival in mice is briefly reported in the literature; therefore, we devised an investigation in mice of the consequences of three standardized cecal ligation lengths on mortality and the severity of the ensued sepsis. Methods Male C57BL/6J mice underwent standardized CLP. The cecum was ligated at 5, 20, or 100 % of its total length and further perforated by a single 20-G puncture. Mortality was analyzed. We assessed blood lactate, serum creatinine levels, and serum cytokines (TNF-α, IL-1β, IL-6, and IL-10) after procedure in a control group and in ligated mice. Results Mortality was directly related to ligation length: median survival was 24 h for the “100 %” group and 44 h for the “20 %” group. Blood lactate increased proportionally with the ligation length. At 6 h post-procedure, pro-inflammatory cytokines significantly increased in the ligated group with significantly higher serum levels of IL-6 in the 100 % group compared to the other ligated groups. The 20 % group exhibited the characteristics of septic shock with hypotension below 65 mmHg, pro-inflammatory balance, organ dysfunction, and hyperlactatemia. Conclusions Cecal ligation length appears to be a major limiting factor in the mouse CLP model. Thus, this experimental model should be performed with high consistency in future protocol designs.

International audience; The performances of Li-ion batteries depend on many factors amongst which the important ones are the electrode materials and their structural and electronic evolution upon cycling. For a better understanding of lithium reactivity mechanism of many materials the combination of X-Ray Powder Diffraction (XRPD) and Transmission Mössbauer Spectroscopy (TMS) providing both structural and electronic information during the electrochemical cycling has been carried out. Thanks to the design of a specific electrochemical cell, derived from a conventional Swagelock cell, such measurements have been realised in operando mode. Two examples illustrate the greatness of combining XRPD and TMS for the study of LiFe0.75Mn0.25PO4 as positive electrode and TiSnSb as negative electrode. Different kinds of insertion or conversion reactions have been identified leading to a better optimization and design of performing electrodes.

International audience; The reaction mechanisms of Li with Sn/BPO4 composites to be used as negative electrode materials for Li-ion batteries were studied during electrochemical cycling by operando Mössbauer spectroscopy and X-ray diffraction using a specifically conceived in situ electrochemical cell. The starting composites consist of three main components: β-Sn particles as the electrochemically active species, an inactive matrix of BPO4 and an amorphous SnII-borophosphate interfacial phase linking the two former components and improving the cohesion of the composite. During the first discharge, the latter Sn(II) species are first reduced to zerovalent tin forming Li-poor Li-Sn alloys. After its complete reduction, the reaction of Li continues with β-Sn leading to Li-Sn alloys increasingly rich in Li, with a final composition between those of Li7Sn2 and Li13Sn5. X-ray diffraction shows a progressive loss of long range order of the composites with the suppression of the diffraction peaks of the initial β-Sn and the formation of an ill-defined mixture of Li-Sn alloys. The evolution of this mechanism is investigated on going from a reference Sn/BPO4 composite prepared by conventional ceramic methods with common micrometric BPO4 to a new improved material prepared by carbothermal synthesis starting from nanometric BPO4. With the new composite prepared by carbothermal synthesis, a significant improvement of the reversible capacity at the first cycle is obtained together with a slight improvement of the cycling behaviour. An additional improvement can be obtained by increasing the rate of the first discharge, and thus hampering the formation of the thermodynamically stable LiSn intermetallic.

The electrochemical reaction mechanism of the Sn–(CaSiO 3 ) 0.4 composite electrode with Li was investigated by electrochemical tests and a variety of spectroscopic techniques. The electrochemical behavior of this material showed a highly reversible reaction with Li after the first discharge with a specific capacity of 530 mAh g −1 at C/10 rate. Some essential steps of the mechanism have been inferred from 119 Sn Mossbauer spectroscopy and the electrochemical potential curve. The composite material contains three tin based phases with different tin oxidation numbers: an amorphous Sn II phase which is reduced into Sn 0 as the first step of the discharge, CaSn IV SiO 5 and β-Sn which are progressively transformed into lithium–tin alloys during the discharge. A Mossbauer spectrum recorded at the end of the discharge reveals the formation of Li 7 Sn 2 . The de-alloying reaction of Li 7 Sn 2 leads to the formation of β-Sn at the end of the charge. X-ray absorption and 119 Sn Mossbauer spectroscopy revealed furthermore that the electrochemical reaction between Li and the Sn–(CaSiO 3 ) 0.4 composite is accompanied by an electron transfer between Li and Sn.

Electronegativity difference Δ x , atomic size parameter δ and width of supercooled liquid region (Δ T x = T x − T g , where T x is the onset crystallization temperature and T g the glass transition temperature) are analysed for glasses of the ternary system Sb 2 S 3 –As 2 S 3 –Sb 2 Te 3 as a function of arsenic atomic percentage. Correlation is investigated between the two bonds parameters (Δ x and δ ) and the width of supercooled liquid region Δ T x (which is generally reliable in estimating the stability against the crystallization of the glasses). It is found that this width of supercooled liquid region of the glasses in Sb 2 S 3 –As 2 S 3 –Sb 2 Te 3 system depends on electronegativity difference and atomic size parameter.

An original carbothermal synthesis of ramsdellites phases under specific atmosphere (Ar, Ar/H 2 , N 2 , N 2 /H 2 ) allowed creating in situ composites which showed good electrochemical properties as negative active materials of Li-ion batteries. The combination of chemical, XRD and electrochemical analyses enabled to identify the as-formed composite electrodes. It consists in ramsdellite/spinel for the synthesis under Ar/H 2 , TiO 2 ramsdellite/Li 2 TiO 3 for the synthesis under N 2 /H 2 , and Li 2± x Ti 3 O 7 /Li 2± x ′ Ti 3 O 7 for the samples prepared under both N 2 and Ar. Carbon is partially inserted inside channels of titanate structure for the sample obtained under Ar/H 2 . For the first time, one of these composites allowed reaching a specific capacity close to the theoretical value of 198 mAh g −1 .

Thanks to the 119Sn Mossbauer hyperfine parameters, it is possible to analyze and predict Li reaction mechanisms with Sn-based negative electrodes for Li-ion batteries. The present approach is based on the interpretation of the 119Sn Mossbauer hyperfine parameters: isomer shift (δ) and quadrupole splitting (Δ) by considering: (i) the analysis of the 119Sn Mossbauer hyperfine parameters of the Li–Sn alloys used as model compounds, (ii) their interpretation from some physicochemical parameters (Li/Sn ratio, crystal structure, electronic density as defined by Hume-Rothery), and (iii) the proposition of an experimental based model to understand Li lithiation/delithiation mechanisms and predict electrochemical performances for Sn-based compounds including the effects of volume variations, particle coalescence or SEI formation.

Ni 3 Sn 4 and CoSn 2 which are two Sn-based intermetallic compounds with different crystal structures have been tested as future negative electrodes for lithium-ion batteries. Various two-step reactions occur during the first discharge of these two electrodes. The first discharge shows good specific capacities: 515 mAh g −1 for the Ni 3 Sn 4 electrode and 606 mAh g −1 for the CoSn 2 electrode. These reactions lead to the formation of Li 7 Sn 2 , a Li-rich Li x Sn alloy characterized by 119 Sn Mossbauer spectroscopy.

International audience; WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: * In burn patients it has been shown ([2]), that there is a correlation between the creatinine clearance (CL(CR)) and the clearance of inulin. * The CL(CR) has never been studied in burn patients who have normal serum creatinine. * The Robert, Kirkpatrick and sMDRD formulae have never been evaluated in burn patients. WHAT THIS STUDY ADDS: * Despite burn patients having normal serum creatinine concentrations, the study showed that there are large variations in CL(CR) which cannot be detected by single serum creatinine measurements, and which have important implications for drug therapy. * It showed that the formulae currently used to calculate creatinine clearance on the basis of serum creatinine are inadequate for use in burn patients, and they should be abandoned in favour of direct measurement from a 24 h urine collection. AIMS: The aim of this study was to evaluate whether the renal function of burn patients could be correctly assessed using a single serum creatinine measurement, within normal limits, and three prediction equations of glomerular filtration taking into account, serum creatinine, age, weight and sex. METHODS: This was a prospective study comprising 36 adult burn patients with a serum creatinine 140 ml(-1) min(-1) 1.73 m(-2)) was found in 13 patients younger than 40 years. Regression analysis, residual and Bland-Altman plots revealed that neither the Cockcroft-Gault, Robert, Kirkpatrick nor sMDRD equations were specific enough for the assessment of renal function. CONCLUSIONS: In burn patients with normal serum creatinine during the hypermetabolic phase, serum creatinine and creatine based predictive equations are imprecise in assessing renal function.

The reaction mechanisms between Sn-(n-C4H9)4 and several specific types of surface sites on alumina are studied. A surface treatment is described allowing the complete elimination of reactive surface sites and avoiding the anchoring of Sn-(n-C4H9)4 on the support. This surface deactivation is applied to the preparation of bimetallic PtSn/Al2O3 catalysts by controlled selective decomposition of Sn-(n-C4H9)4 on the reduced metallic particles of a Pt/Al2O3 catalyst. The resulting bimetallic particles are analysed by 119Sn Mossbauer spectroscopy at different stages of the preparation procedure. The tin anchoring sites on the platinum particles are identified on the basis of their specific Mossbauer hyperfine parameters. Tin atoms in contact with the support or with platinum are distinguished from those enclosed in bulk-SnO2-like agglomerates. A structural model is proposed describing at an atomic scale the morphology of the bimetallic particles and their evolution under various heat treatments. The results are compared with those of a catalyst prepared by conventional impregnation methods on a not specifically pretreated support.

Several Li–Sn crystalline phases, i.e. Li 2 Sn 5 , LiSn, Li 7 Sn 3 , Li 5 Sn 2 , Li 13 Sn 5 , Li 7 Sn 2 and Li 22 Sn 5 were prepared by ball-milling and characterized by X-ray powder diffraction and 119 Sn Mossbauer spectroscopy. The analysis of the Mossbauer hyperfine parameters, i.e. isomer shift ( δ ) and quadrupole splitting ( Δ ), made it possible to define two types of Li–Sn compounds: the Sn-richest compounds (Li 2 Sn 5 , LiSn) and the Li-richest compounds (Li 7 Sn 3 , Li 5 Sn 2 , Li 13 Sn 5 , Li 7 Sn 2 , Li 22 Sn 5 ). The isomer shift values ranged from 2.56 to 2.38 mm s −1 for Li 2 Sn 5 , LiSn and from 2.07 to 1.83 mm s −1 for Li 7 Sn 3 , Li 5 Sn 2 , Li 13 Sn 5 , Li 7 Sn 2 and Li 22 Sn 5 , respectively. A Δ − δ correlation diagram is introduced in order to identify the different phases observed during the electrochemical process of new Sn-based materials. This approach is illustrated by the identification of the phases obtained at the end of the first discharge of η -Cu 6 Sn 5 and SnB 0.6 P 0.4 O 2.9 .

Background In ICU patients with normal serum creatinine (SCr), a state of increased renal drug excretion has been described (creatinine clearance ≥130 ml/min/1.73 m2), and named augmented renal clearance (ARC). In ICU patients, the accuracy of GFR estimates is insufficient. However, in clinical practice, the physician has not at one’s disposal patient measured creatinine clearance (CrCl) when prescribing. The primary objective of this study was to assess the accuracy of 4 formulas to estimate GFR (Cockcroft-Gault (CG), Robert, sMDRD, and CKD-EPI formulas) with other covariates to detect ARC in ICU patients. Methods We enroled 360 consecutive ICU patients with normal SCr in this prospective observational study conducted in a primary teaching hospital. Comparisons between CrCl values and 4 estimated GFR (eGFR) formulas were estimated. Results In these 360 patients, ARC was observed in 33 % of patients most of them trauma. Individual predictive values of equations were poor and the phenomenon increased in ARC subgroup. CG and CKD-EPI were more accurate to detect an ARC. Multivariable analysis showed that the best-fitting model included 3 factors independently correlated to ARC: trauma patients, cut-off values of age ≤58 years, and CKD-EPI more than 108 ml/min/1.73 m2. Conclusions In ICU patients with normal SCr, eGFR formulas are imprecise in assessing CrCl. If measured CrCl must be ideally used to detect modifications of the renal function, in clinical practice, age, reason for admission, and CKD-EPI could be used as screening tool to identify ARC.

Sn-based composite materials were synthetized by a conventional meltquenching method, and studied by X-ray diffraction, electrochemistry and in situ 119Sn Mosssbauer spectroscopy. Tin was dispersed ex situ into a matrix formed from B2O3:P2O5. XRD and 119Sn Mossbauer spectroscopy show the formation of an interface between the active species (Sn0) and the matrix. This amorphous interface acts as a “buffer-zone” which compensates volume changes during the tin-lithium alloy formation and avoids aggregation of tin particles.

Electrochemistry requires a stable structure to avoid capacity loss. Substitution of structural Ti and Li by 3d transition elements in the Li2Ti3O7 ramsdellite structure has been considered in order to improve the accessibility of the vacancies. In the case of a one element substitution, Ti/Fe, the reduction FeIII to FeII gives rise to an irreversible part in the electrochemical curves. For the substitution of Ti/Li by two transition elements, Fe and Ni, only a partial FeIII/FeII reduction occurs, resulting in a smaller irreversible plateau and improved cyclability. This reduction has also been evidenced by 57Fe Mossbauer spectroscopy in which 57Fe is used as a local probe giving valuable information about its local environment, thus allowing deeper insight into the lithium insertion mechanism.

For the search of new negative electrodes of Li-ion batteries, a low-temperature method has been developed for the preparation of nanoscale antimony particles which uses an alkoxide-activated sodium hydride as reducing agent of antimony pentachloride. X-ray diffraction and TEM studies confirm the obtaining of amorphous Sb nanoparticles dispersed in an organic matrix. 121Sb Mossbauer spectroscopy gives evidence for the occurrence of interactions between antimony and the matrix. These interactions are modified by the washing treatments.

119Sn Mossbauer spectroscopy at 77 K was used to observe surface tin atoms on PtSnx/SiO2 catalysts. Two families of PtSnx/SiO2 catalysts with fully reduced Pt(0) and Sn(0) atoms were prepared following the Surface Organo-metallic Chemistry on Metal strategy. These two families of catalysts exhibit about the same Sn/Pt composition, but very different metallic particle diameters, each with narrow particle size distribution, so that, the ratio between surface tin atoms and “bulk” tin atoms was significantly different for the two families. In addition to the well known “Pt-Sn” bulk alloy with small quadripole splitting, a new Pt-Sn species with large quadripole splitting and isomer shift in the range of Sn(0) was observed. The relative proportion of this species with respect to “Pt-Sn” bulk alloy is greater for small particles than for the larger ones, which suggests that this species is a surface tin atom present in a “Pt-Sn” alloy.

The combination of non-opioid analgesic drugs, though widely used, has been rarely evaluated. The aim of this study was to compare the efficacy of propacetamol and the non-steroidal analgesic drug ketoprofen, alone or in combination, on pain relief after thyroid surgery performed using remifentanil.Ninety-seven patients were randomly allocated to one of the three groups: propacetamol 2 g (32), ketoprofen 100 mg (33) and propacetamol 2 g + ketoprofen 100 mg (32). Each regimen was administered intravenously (i.v.) 30 min before the end of surgery and then every 6 h. If pain was not relieved, patients received an i.v. bolus of tramadol 100 mg. Tramadol consumption and pain intensity using a visual analogue scale was recorded at 1, 2, 8 and 14 h after the end of surgery.Pain scores were significantly higher with propacetamol compared with ketoprofen 2 h after surgery (35 +/- 3.7, 21 +/- 2.6, respectively; P0.01). The number of patients receiving tramadol was higher with propacetamol alone compared with the two other groups, 1 h (14/32, 4/33, 2/32, respectively; P0.01) and 2 h (24/32, 6/33, 8/32, respectively; P0.01) after surgery. There was no difference between ketoprofen alone and ketoprofen plus propacetamol, and there was no difference between the three groups from the 8th hour onward.In the immediate postoperative period after thyroid surgery performed using remifentanil, the concomitant use of propacetamol and ketoprofen does not improve analgesia compared with ketoprofen alone.

Lithium has been inserted into the spinel Li4Ti5O12 by both chemical and electrochemical methods. The cation distribution in the lithiated phases has been analyzed by 6,7Li NMR, Raman spectroscopy, and X-ray diffraction, and the distribution in the chemically inserted compound has been analyzed additionally by neutron diffraction. A refinement of structural parameters has been carried out by applying the Rietveld method to the neutron diffraction pattern. It is shown that the two insertion methods are based on different mechanisms. Chemically inserted lithium ions are trapped in the (48f) sites of the spinel structure from which they cannot be extracted by electrochemical means. In contrast to the electrochemical Li-insertion, which is accompanied by a spinel to rocksalt phase transition, no such structural change is found for chemical insertion. The consequences of the two different mechanisms for the reversibility of the insertion process are discussed.

A high-voltage (5 V) LiCo 0.8 Fe 0.2 MnO 4 electrode with spinel-type structure has been prepared. 57 Fe Mossbauer spectra reveal high-spin Fe 3+ ions in octahedral coordination in the pristine sample, which are oxidized to tetravalent iron ions. Surface treatments with zinc and magnesium have been applied. Zinc and magnesium were homogenously distributed, according to EPMA and mapping analysis, while the spinel structure is maintained. The magnesium and the zinc treatments drive to better electrochemical performance and capacity retention.

X-ray absorption spectra of the spinel In2S3 were recorded at the sulphur K and indium L1 and L3 absorption edges, scanning the unoccupied electronic states of S p, In p, and In (s,d) symmetry, respectively. Alignment of all spectra on a common scale and comparison with calculated densities of states allowed an interpretation of all observed features in terms of final state character, chemical bonding and local symmetry. A picture of the conduction band structure is established.

Surface organometallic chemistry has been used to deposit tin atoms on an alumina-supported cobalt–molybdenum sulfide. The EXAFS spectra at the Mo and Co K-edges were not changed significantly by tin doping, which means that the initial morphology of sulfide phases was preserved during the synthesis. 119 Sn Mossbauer spectroscopy indicated that the main neighbors of the deposited tin atoms were sulfur and oxygen atoms with no significant formation of metallic tin particles. Tin seems thus to have been deposited either on the sulfide slabs through sulfur bridges or on the support via oxygen bonding. According to the infrared spectroscopy, tin doping led to the blocking of different surface sites with slight electronic structure modification. Those surface sites are sulfur vacancies on sulfide slabs, Al3+ or hydroxyl groups on the support, or “interfacial” sites: support hydroxyl groups H-bonded with sulfide phases. The impact of tin doping on the activity and selectivity of the sulfide phases was studied by catalytic tests carried out using a synthetic FCC gasoline feed. Three main reactions were found to be involved: hydrodesulfurization of sulfur-containing molecules, double-bond isomerization and hydrogenation of olefins. Olefin hydrogenation was preceded by double-bond isomerization reaction, which gave quickly thermodynamically equilibrated composition. No clear correlation could be made between tin doping and isomerization performance and catalyst support was proposed as the main actor for this reaction. Small amounts of tin had little effect on the hydrogenation activity, but higher loadings resulted in an important decrease in activity. Contrary to the case of olefin hydrogenation, thiophene hydrodesulfurization activity decreased drastically at a low tin loading, and continued to decrease but more slightly at higher loadings. By comparison of the activity variations and the characterization results, the sulfur vacancies were found to play a major role in the hydrodesulfurization process. Interfacial sites were assumed to be involved in one of the key steps in the olefin hydrogenation pathway.

The electronic structure of the spinel compound Li4Ti5O12, used as anode material in Li-ion batteries, is studied both theoretically and experimentally. The partial densities of occupied and vacant s, p and d electronic states were calculated for Li, Ti and O, using the linear augmented plane wave formalism (LAPW) in order to obtain information on the chemical bond. X-ray absorption spectra were recorded at the Ti L23, Ti K and O K absorption edges and calculated within the dipolar approximation by considering both the electronic ground state and the effect of core holes. The atomic origin of the observed main peaks is analysed from the comparison between the experimental and calculated spectra. We show that the two types of lithium in Li4Ti5O12 which are found in tetrahedral and octahedral sites could be distinguished by X-ray absorption spectroscopy. We suggest to use such a technique for the investigation of Li-insertion mechanisms in lithium titanate spinels.

Lithium reaction mechanism in amorphous tin composite oxide SnB0.6P0.4O2.9 is characterized by X-ray diffraction, 119Sn Mossbauer spectroscopy and X-ray absorption fine structure. The analysis of the experimental data concerning SnB0.6P0.4O2.9 shows that SnII is highly ionic and is surrounded by three oxygen atoms. The detailed analysis of lithium insertion mechanism shows a complex reduction mechanism in two steps. During the first one the main reaction corresponds to a partial SnII reduction, involving a mixed valence system. It is accompanied by modifications of tin environments, while lithium acts as a network modifier inducing the formation of nonbridging oxygen atoms. The second step corresponds to LiSn alloying process, with the formation of LiSn bonds. It is worth noting the persistence of SnO interactions in this second step. The reversible part of the mechanism can be explained from the formation of small particles of lithium–tin alloys in strong interaction with the oxygen atoms in the glass matrix, while the vitreous support presents an interesting dispersal effect.

Colloidal oxide synthesis is a new technique for the preparation of bimetallic supported particles which provides the opportunity to control particle size distribution and interaction between both metals. It consists in synthesizing in aqueous medium a sol of colloidal oxide Pd–Sn nanoparticles which is further deposited onto a porous support. In this work, this method has been applied to the preparation of Pd–Sn/Al2O3 dedicated to the selective hydrogenation of unsaturated hydrocarbons. Two synthesis routes, surface precipitation and surface adsorption, are described to demonstrate the potential of colloidal oxide chemistry to generate a bimetallic interaction in aqueous solution which is strengthened during the reduction step after deposition onto alumina. 119Sn Mossbauer spectroscopy (119Sn MS) and transmission electron microscopy (TEM) were used to characterize the sols and the supported catalysts. This allowed us to determine the key parameters of colloidal oxide synthesis as far as formation of bimetallic PdxSny phases is concerned.

Lithium insertion mechanism in some antimony-based compounds: SnSb, CoSb3, CrSb2, TiSb2 has been studied by means of 121 Sb Mossbauer spectrometry which gives valuable information about the local electronic structure of the probed element (Sb). The structural and electronic modifications induced by insertion of lithium have been characterized. For these Sb-based materials the lithium insertion mechanisms involve Li3Sb formation and composite multi-phase separations with one component displaced from the pristine compound.

The irreversible mechanisms of lithium insertion in amorphous tin composite oxides SnB 0.6 P 0.4 O 2.9 have been studied by X-ray diffraction (XRD) and 119 Sn Mossbauer spectroscopy. The determination of the Lamb–Mossbauer factor has allowed us to evaluate the relative numbers of different tin atoms (Sn II , Sn 0 ). We show that insertion of lithium reduces the Sn II into Sn 0 atoms, which form nanoparticles of active species. The lithium ions act as glass modifiers, breaking the bonds within MOM′ (M, M′=B, P, Sn) bridges and forming non-bridging MO δ − bonds.

The spinel Li4Ti5O12, a stable phase of the Li2O–TiO2 system, allows to insert three Li atoms per formula unit at a potential of 1.5 V on the basis of a spinel ↔ NaCl phase transition. This mechanism leads to a reduction of three Ti(IV) atoms out of five, corresponding to a theoretical capacity of 175 mAh/g. The influence of structural defaults on the spinel → NaCl phase transition and its reversibility during charge/discharge cycles have been studied. Solid solutions formed from chemical insertion of lithium or substitutions Ti/V, Ti/Mn, Ti/Fe modify the cation distribution on the crystallographic sites (tetrahedral 8a, octahedral 16d, space group Fd3m) and influence the electrochemical performances. A structural analysis by X-ray and neutron diffraction, X-ray absorption, 57 Fe Mossbauer spectroscopy and first principle calculations have allowed to establish a relationship between the structure and the electrochemical properties.

The mixed transition-metal spinel oxide NiFe2O4 is used for the first time as active electrode materials vs. lithium metal in test cells. Reversible capacities close to 900 mAh/g are found. Due to the poorly crystalline nature of the products of electrochemical reaction, diffraction procedures give little information about the iron forms in the reaction products. The use of 57Fe Mössbauer spectroscopy allows to monitor the mechanism of the electrochemical reaction with lithium of the spinel. During the first discharge, the amorphization process is accompanied by metal reduction. The reversible redox reaction FeIII↔Fe0 accounts for the cycling capacity. However, magnetic ordering is lost during the first discharge and is not recovered in subsequent cycling or in the iron metal products. Keywords: Lithium batteries, Negative electrode, Mixed spinel oxides, Mössbauer spectroscopy, Iron oxide reduction

The electrochemical reaction of lithium with the skutterudite-type CoP3 compound has been studied. To follow the reaction mechanism, X-ray diffraction (XRD), 7 Li nuclear magnetic resonance (NMR) and X-ray absorption (XAS) experiments have been carried out. During the first reaction of the CoP3 phase, cobalt is reduced and lithium-phosphide is formed. The reversible process observed during subsequent cycles consists of the formation of Li3P from its elements, giving a maximum in reversible gravimetric capacity of 487 mAh/g.

119Sn Mossbauer spectroscopy is used in combination with 7Li MAS NMR spectroscopy and X-ray diffraction to resolve the details of the different Li−Sn and Li−Sb intermetallics formed during the elec...

The modification of metal oxide surfaces by π-conjugated ferrocene units has been performed. A phosphonic acid functionality was used to covalently anchor the π-conjugated ferrocene moiety to SnO2 and TiO2 particles. The covalent attachment and the monolayer coverage at the surface of the particles were confirmed by solid-state MAS 31P NMR spectroscopy, microanalysis and electronic microscopy (EDX). The properties of the ferrocene-modified oxides were analysed by cyclic voltammetry, which confirmed the electroactivity of the material, and 57Fe Mossbauer spectrometry, which provided information about the oxidation state and environment of the iron atoms. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

The phosphate adsorption properties of three clay samples, with kaolinite as the dominant mineral, from different deposits in the Ivory Coast have been investigated. The clays contain varying amounts of crystalline Fe oxides and kaolinite with structural Fe. All measurements were made in dilute suspension under controlled conditions of temperature, pH, ionic strength and saturating cation. Data have been fitted to Langmuir adsorption isotherms. Both P adsorption and surface area measurements have been made on samples before and after chemical removal of Fe oxides. The samples have large P adsorption capacities, which are not entirely explained by their large specific surface areas. The presence of Fe oxides makes a strong contribution to the surface area and enhances the adsorption capacities. There is little evidence that structural Fe makes a strong contribution to the enhanced P adsorption capacity.

Te-M€ spectroscopy was used in order to study the change in the local chalcogen environment of Cu-Ag- As-Se glasses showing anomalies in the Ag þ ion transport. These ion-conducting glasses with a constant silver content of 15 at.% and variable copper concentration, x, exhibit (i) a dramatic decrease in the 110 Ag tracer diffusion coefficient, DAg, by two orders of magnitude at 0 6 x 6 10, and (ii) a nearly complete DAg recovering at 10 6 x 6 20. The parabolic shape of DAg is accompanied by a similar composition dependence of the quadrupole splitting, QS, which reflects changes in the Te-M (M ¼ Ag, Cu) and Se-Ag interatomic distances. The minimal chalcogen - silver distance at x ¼ 10 at.% Cu corresponds to the minimal value of DAg. 2002 Elsevier Science B.V. All rights reserved.

We propose an alternative approach for the analysis of the Mossbauer spectra of complex crystalline materials when the determination of the Mossbauer parameters from the only experimental data fails. This approach is based on first principle calculations of the electron density and electric field gradients at the nucleus based on the linearized augmented plane wave method. Results are given for tellurium and antimony compounds.

The solar thermochemical dissociation of H2O and CO2 for renewable fuel production from two-step SnO2/SnO cycle is considered. This cycle is based on the solar production of SnO phase in a first endothermic step that is subsequently used for splitting CO2 and H2O in a second exothermic step. The reactivity of tin-based species was studied in order to elucidate the phenomena occurring during its heating and subsequent reoxidation in a H2O or CO2 atmosphere to produce H2 or CO. Two main types of reactant were considered for comparing their reactivity: SnO nanopowder obtained via solar sublimation and condensation of commercial SnO powder, and Sn/SnO2 nanopowder obtained via disproportionation of nanosized SnO. The reaction rate was quantified via thermogravimetry analysis and the reaction products were characterized using Mossbauer spectrometry and X-ray diffraction. The SnO and Sn/SnO2 nanopowders are more reactive with H2O than with CO2 in the range 550–650 °C. SnO is also more reactive with oxidants than...

The electronic structures of As 2 Te 3 , GeTe and the layered compounds As 2 Ge n Te 3+ n with n =1–5 have been experimentally studied by means of X-ray photoemission spectroscopy (XPS). The XPS valence bands show changes as a function of n , which are explained by tight-binding calculations of the total and partial densities of states. The values of the binding energy of the Ge 3d 5/2 , As 3p 3/2 , and Te 3d 5/2 core-levels were measured and are related to the calculated atomic charges.

The electrochemical insertion of lithium into β-In2S3 at different concentrations has been investigated by means of γγ-Perturbed Angular Correlations measurements using implanted radioactive 111In nuclei. The study of the hyperfine interactions of the 111Cd nuclei during the decay 111In(EC)111Cd allowed to determine the evolution of the three observed electric field gradients at different temperatures and lithium contents. This study reveals a great difference of behavior between the three indium sites of the structure, and shows the mobility of indium ions and their partial reduction after lithium insertion. In2S3 is good model material to study the properties of more complex materials based on this structure, which may be used as electrodes for lithium-ion batteries.

We studied the reduction mechanism of SnO in lithium cells by X-ray absorption near OK and SnL I edge spectroscopy, 119 Sn Mossbauer spectroscopy and X-ray diffraction. The reduction mechanism is complex, involving mixed valence intermediate compounds. In the interval 0≤Li/Sn≤2 the main reaction corresponds to a partial reduction of Sn II , which is partially reversible, regenerating the tin oxide during the charge. For Li/Sn greater than two, LiSn bonds are formed, but SnO interactions are still present. The charge within this interval also partially regenerates tin oxide, but the reversibility does not extend to Li/Sn lower than two. At low voltage and very large depth of discharge, the formation of LiSn alloys and Li 2 O clearly takes place, with negligible SnO interactions.

cited By 23; International audience; The electrochemical reaction of lithium with triclinic FeVO4 (a = 6.714(1) Å, b = 8.060(2) Å, c = 9.352(2) Å, α = 96.678(1)°, β = 106.641(1)°, and γ = 101-523(1)°, P-1) has been investigated by means of 57Fe Mössbauer spectroscopy in order to complement the previous X-ray diffraction and X-ray absorption near edge structure studies on the same system. A complex FeIII → FeII → Fe0 or FeIII → FeII ,Fe0 reduction process has been detected upon the first discharge of the battery down to 0.02 V, with in addition the iron reoxidation during the next charge step. A mechanism based on "lithium adsorption" is proposed in order to explain this unexpected behavior.

The electronic structure of Ge0.2Te0.8 and Ge0.1AsxTe0.9−x glasses with x=0.2, 0.46 and 0.54 has been experimentally determined by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The values of the Ge 3p3/2, As 3p3/2 and Te 3d5/2 core level binding energy do not vary significantly within this series of glasses in agreement with the covalent character of the bonds. The atomic contributions to the main observed peaks in the XPS valence bands and XAS spectra are obtained from a molecular calculation. This approach is first used for crystalline As2Te3 and compared to a periodic tight-binding calculation in order to check its accuracy for the analysis of the experimental data in terms of local environments. The electronic structure of Ge0.2Te0.8 is consistent with the existence of GeTe4 units connected by Te–Te bonds but does not rule out the presence of Ge–Ge bonds. The XPS valence bands of the ternary glasses are formed by two broad bands which are due to the s- and p-type valence electrons of the different atoms, respectively. Increase of the As content mainly changes the p-type peak and the main XAS peaks at the As K and Ge K edges. These changes are due to the decrease in the number of As–Te bonds and the increase in the number of As–As bonds.

Photoemission spectroscopy and X-ray emission spectroscopy have been used to investigate the role of the chemical environment on the electronic structure of SnS, SnS2, Sn2S3 and Li0.57SnS2 compounds. For this purpose, we have studied the Sn 3d5/2 and S 2p1/2,3/2 inner levels and the valence band by photoemission spectroscopy and the S 3p electronic distributions by X-ray emission spectroscopy. We have established fingerprints of the SnII and SnIV valencies in the compounds SnS and SnS2 and have shown that these are observed in Sn2S3 where it is known that both II and IV valencies are present. By comparing the data for Li0.57SnS2 with those for the other compounds, we have demonstrated that the SnII and SnIV signatures are also found in this compound. We have thus ascertained experimentally that Sn is partially reduced in SnS2 upon Li intercalation. In addition, the data have been found to be in excellent agreement with recent densities of electronic states calculations performed in the framework ...

The metal−citrate method is applied to the preparation of microcrystalline tin dioxide and aluminum-doped materials. The effect of the precursor composition, referred to as the metal/citrate ratio, and the thermal treatment are discussed. The different compositions produce upon thermal decomposition rutile-type SnO2 solids. For Al-containing oxide materials, Al(III) ions occupy octahedral sites isomorphic to Sn(IV), as shown by 27Al MAS NMR signals at ≈0 ppm and 119Sn Mossbauer signals at 0 mm/s isomer shift and 0.53 mm/s quadrupole splitting, respectively. A large microstrain content is released by successive thermal treatments at 450 °C. Simultaneously, extended defects, which imply deviations from an MO2 stoichiometry, are found upon heating. These phenomena condition the ability of the oxide products to be used as the active anode material in lithium-ion batteries. The best electrochemical performance of lithium anode cells is achieved for 10% Al-containing ex biscitrate oxides in which ≈200 Ah/kg cap...

cited By 2; International audience; Electrochemical and chemical lithium insertion (via n-butyllithium) were carried out on a family of spinel phases of the Cu2S-In 2S3-SnS2 system. Electrochemical measurements have revealed great reversible capacities and the possible use of these materials as negative electrodes in lithium-ion batteries, ll9Sn Mössbauer spectroscopy, 7Li NMR and S K edge EXAFS spectroscopy were carried out to characterize the mechanisms of lithium insertion. This study has shown the formation of lithium-metal alloys finely dispersed in an amorphous lithium sulfide matrix at low potentials. A model is proposed to explain the great capacities observed in these materials.

Resume Phospholipase A 2 are enzymes that hydrolyse the sn -2 position of glycerophospholipids, and play a pivotal role in the generation of lipid inflammatory mediators. The type IIA secretory phospholipase A 2 (sPLA 2 ) is a distal effector of inflammation, produced by a number of cells challenged with inflammatory stimuli such as tumor necrosis factor or interleukin-1. Hydrolysis of the glycerophospholipids generates arachidonic acid, which is implicated in eicosanoid synthesis, and some important lipid mediators such as lyso-platelet activating factor, lysophosphatidic acid (LPA), or lysophosphatidylcholine (LPC). High levels of sPLA 2 are found in the plasma of patients suffering from sepsis, septic shock, adult respiratory distress syndrome and multiple organ failure. The levels are correlated to the intensity of the systemic inflammatory response and possibly to the outcome. This review presents important results concerning the pathophysiological implications of sPLA 2 in inflammatory disorders. We also present the role of LPA and LPC. The utility of the determination of sPLA 2 activity in clinical practice is discussed.