Oxygen storage capacity and structural flexibility of LuFe2O4+x (0≤x≤0.5).

Combining functionalities in devices with high performances is a great challenge that rests on the discovery and optimization of materials. In this framework, layered oxides are attractive for numerous purposes, from energy conversion and storage to magnetic and electric properties. We demonstrate here the oxygen storage ability of ferroelectric LuFe2O4+x within a large x range (from 0 to 0.5) and its cycling possibility. The combination of thermogravimetric analyses, X-ray diffraction and transmission electron microscopy evidences a complex oxygen intercalation/de-intercalation process with several intermediate metastable states. This topotactic mechanism is mainly governed by nanoscale structures involving a shift of the cationic layers. The ferrite is highly promising because absorption begins at a low temperature (~=200 °C), occurs in a low oxygen pressure and the uptake of oxygen is reversible without altering the quality of the crystals. The storage/release of oxygen coupled to the transport and magnetic properties of LnFe2O4 opens the door to new tunable multifunctional applications.

Vascular aphasia outcome after intravenous recombinant tissue plasminogen activator thrombolysis for ischemic stroke.

INTRODUCTION: No data about the specific outcome of aphasia after thrombolysis are available. Our aim was to describe the severity and type of aphasia after stroke thrombolysis. METHODS: This retrospective cohort study included consecutive aphasic patients hospitalized in the Stroke Unit of Dijon (University Hospital, France) between 2004 and 2009 for a first-ever ischemic stroke of the left middle cerebral artery. Aphasic syndromes and their severity (French version of the Boston Diagnostic Aphasia Examination) were evaluated during the first week and 3 months after stroke. RESULTS: In multivariate analyses, the severity of aphasia in the 37 thrombolysed patients was milder than in the 38 nonthrombolysed patients during the first week (adjusted OR = 10.13, 95% CI: 2.43-42.28, p = 0.002) and at 3 months (adjusted OR = 8.44, 95% CI: 2.76-25.80, p = 0.001). The frequency of mild aphasia (conduction or atypical) was not significantly higher in thrombolysed patients during the first week after stroke (adjusted OR = 5.80, 95% CI: 0.82-41.16, p = 0.079). CONCLUSION: The severity of aphasia during the first week and 3 months after stroke is milder in thrombolysed than in nonthrombolysed patients, perhaps because of a greater frequency of conduction and mild atypical aphasia.

Stroke care organization overcomes the deleterious 'weekend effect' on 1-month stroke mortality: a population-based study.

BACKGROUND AND PURPOSE: Suffering a stroke during the weekend is associated with a poorer prognosis. The impact of implementing a dedicated stroke care network in Dijon, France, in 2003 on 30-day mortality in strokes/transient ischaemic attacks (TIA) occurring during weekends/bank holidays was evaluated. METHODS: All cases of stroke and TIA from 1985 to 2010 were identified from a population-based registry, using multiple overlapping sources of information. Demographics and clinical data were recorded. Cox regression models were used to evaluate associations between day of onset (weekdays versus weekends/bank holidays) and 30-day all-cause mortality. Data were stratified according to time periods [before (1985-2003) and after (2004-2010) implementation of the stroke network] and stroke subtypes (ischaemic stroke and intracerebral hemorrhage). RESULTS: Of the 5864 recorded patients, 1465 (25%) had their event during weekends/bank holidays. Patients with stroke/TIA during weekdays were comparable with those with stroke/TIA during weekends/bank holidays for baseline characteristics. Excess mortality was observed in patients with stroke/TIA during weekends/bank holidays during 1985-2003 (18.2% vs. 14.0%, P < 0.01) but not during 2004-2010 (8.4% vs. 8.3%, P = 0.74). Onset during weekends/bank holidays was associated with a higher risk of 30-day mortality during 1985-2003 (adjusted hazard ratio 1.26; 95% CI 1.06-1.51, P = 0.01), but not during 2004-2010 (adjusted hazard ratio 0.99; 95% CI 0.69-1.43, P = 0.97). CONCLUSION: The deleterious effect of weekends/bank holidays on early stroke mortality disappeared after the organization of a dedicated stroke care network in our community. Our findings provide strong support for the implementation of quality improvement initiatives in order to attenuate inequalities in the management of stroke patients.

Serum 25-hydroxyvitamin D predicts severity and prognosis in stroke patients.

BACKGROUND AND PURPOSE: We aimed to evaluate the association between 25-hydroxyvitamin D (25(OH)D) levels and both clinical severity at admission and outcome at discharge in stroke patients. METHODS: From February 2010 to December 2010, consecutive stroke patients admitted to the Department of Neurology of Dijon, France, were identified. Clinical information was collected. Serum concentration of 25(OH)D was measured at baseline. Stroke severity was assessed at admission using the NIHSS score. Functional impairment was evaluated at discharge using the modified Rankin scale (m-Rankin). Multivariate analyses were performed using logistic regression models. RESULTS: Of the 386 recorded patients, serum 25(OH)D levels were obtained in 382 (median value = 35.1 nM; IQR = 21-57.8). At admission, 208 patients had a NIHSS ≤5, with a higher mean 25(OH)D level than that observed in patients with moderate-to-high severity (45.9 vs. 38.6 nM, P < 0.001). In multivariate analyses, a 25(OH)D level in the lowest tertile (<25.7 nM) was a predictor of a NIHSS ≥6 (OR = 1.67; 95% CI = 1.05-2.68; P = 0.03). The mean 25(OH)D level was lower in patients with moderate-to-severe handicap at discharge (m-Rankin 3-6) than in patients with no or mild handicap (35.0 vs. 47.5 nM, P < 0.001). In multivariate analyses, the lowest tertile of 25(OH)D level (<25.7 nM) was associated with a higher risk of moderate-to-severe handicap (OR = 2.06; 95% CI = 1.06-3.94; P = 0.03). CONCLUSION: A low serum 25(OH)D level is a predictor of both severity at admission and poor early functional outcome in stroke patients. The underlying mechanisms of these associations remain to be investigated.

Prestroke antiplatelet therapy and early prognosis in stroke patients: the Dijon Stroke Registry.

BACKGROUND AND PURPOSE: Previous antiplatelet therapy (APT) in cardiovascular prevention is common in patients with first-ever stroke. We aimed to evaluate the prognostic value of APT on early outcome in stroke patients. METHODS: All first-ever strokes from 1985 to 2011 were identified from the population-based Stroke Registry of Dijon, France. Demographic features, risk factors, prestroke treatments and clinical information were recorded. Multivariate analyses were performed to evaluate the associations between pre-admission APT and both severe handicap at discharge, and mortality at 1 month and 1 year. RESULTS: Among the 4275 patients, 870 (20.4%) were previously treated with APT. Severe handicap at discharge was noted in 233 (26.8%) APT users and in 974 (28.7%) non-users. Prestroke APT use was associated with lower odds of severe handicap at discharge [adjusted odds ratio (OR): 0.79; 95% confidence interval (CI): 063-1.00; P = 0.046], non-significant better survival at 1 month [adjusted hazard ratio (HR): 0.87; 95% CI: 0.70-1.09; P = 0.222] and no effect on 1-year mortality (HR: 0.94; 95% CI 0.80-1.10; P = 0.429). In stratum-specific analyses, APT was associated with a lower risk of 1-month mortality in patients with cardioembolic ischaemic stroke (HR: 0.65; 95% CI: 0.43-0.98; P = 0.040). CONCLUSIONS: APT before stroke was associated with less severe handicap at discharge, with no significant protective effect for mortality at 1 month except in patients with cardioembolic stroke. No protective effect of APT was observed for mortality at 1 year. Further studies are needed to understand the mechanisms underlying the distinct effects of prior APT observed across the ischaemic stroke subtypes.

Sr7Co4(CO3)O(13-δ) (δ = 1.64), an original cobaltite derivative of the Ruddlesden-Popper series.

The oxycarbonate Sr7Co4(CO3)O11.36 exhibits a peculiar structure that has been characterized by combining transmission electron microscopy analyses and neutron diffraction. It consists of a regular intergrowth between the m = 2 and carbonated m = 3 members of the Sr(m+1)Co(m)O3(m+1) Ruddlesden-Popper (RP) series, Sr3Co2O5.87 and Sr4Co2(CO3)O5.49, respectively. A description of the structure is proposed to provide identification of the different building blocks. This material is semiconducting and presents a complex magnetic behavior, characteristic of what is observed for the RP(2) or RP(3) series, with a cobalt valency close to 2.7.

One-year survival of demented stroke patients: data from the Dijon Stroke Registry, France (1985-2008).

BACKGROUND AND PURPOSE: Dementia is a frequent condition after stroke that may affect the prognosis of patients. Our aim was to determine whether post-stroke dementia was a predictor of 1-year case-fatality and to evaluate factors that could influence survival in demented stroke patients. METHODS: From 1985 to 2008, all first-ever strokes were recorded in the population-based stroke registry of Dijon, France (150, 000 inhabitants). Dementia was diagnosed during the first month following stroke, according to DSM-III and DSM-IV criteria. Survival was evaluated at 1 year and multivariate analyses were performed using Cox proportional hazards to identify independent predictive factors. RESULTS: We recorded 3948 first-ever strokes. Among these stroke patients, 3201 (81%) were testable, and of these, 653 (20.4%) had post-stroke dementia (337 women and 316 men). Demented patients had lower 1-year survival than patients without dementia (82.9% vs. 86.9%, P = 0.013). However, in multivariate analysis, dementia did not appear as an independent predictor of 1-year death. In demented stroke patients, age >80 years old, severe handicap at discharge, recurrent stroke within the first year and subarachnoid haemorrhage were associated with a higher risk of 1-year death, and the risk was lower in the study period 2003-2008. CONCLUSIONS: Dementia after stroke is not independently associated with an increased risk of death at 1 year. In recent years, 1-year case-fatality decreased in demented as well as in and non-demented patients suggesting that improvements in the management of stroke also benefited the most fragile patients.

Pressure-induced structural transition in LuFe2O4: towards a new charge ordered state.

The electronic ferroelectric lutetium ferrite (LuFe(2)O(4)) was studied by x-ray diffraction as a function of pressure. Pressure is shown to induce an irreversible rhombohedral to orthorhombic transition leading to a supercell determined by the combination of electron and synchrotron x-ray diffraction. This new configuration is proposed to be charge ordered in agreement with the results of resistivity measurements.

The modulated structure of the calcium aluminate Ca6(AlO2)12·Bi2O3.

Bismuth calcium aluminate, Bi(2)Ca(6)Al(12)O(27), has been prepared as a ceramic and a single crystal. Analysis of reciprocal space using both electron and X-ray diffraction show an R-centred hexagonal unit cell: a = b = 17.3892 (4), c = 6.986 (1) Å. Additional weak reflections are observed; they require the introduction of a modulation wavevector q = 0.0453 (2)c* for indexing. The modulated structure has been solved using the superspace formalism [superspace group X3(00γ)0]. A framework of corner-sharing AlO(4) tetrahedra forms corrugated sixfold rings and uncommon triple rings. The Ca(2+) cations exhibit an eightfold coordination sphere; edge-sharing CaO(8) polyhedra form intertwinned zigzagging rows along c creating a three-dimensional net. Bi atoms are located in large hexagonal tunnels parallel to c and form Bi(2)O(3) pairs, which adopt a trigonal bipyramidal configuration. The 6s(2) lone-electron pairs (Lp) point along c, in the opposite direction to the three Bi-O strong bonds to form two BiO(3)Lp tetrahedra with a common base. Different orientations of the Bi(2)O(3)Lp(2) pairs, rotated by 60° around c, are observed. Their stacking modes in each of the hexagonal tunnels are described. The sequence of the stacking varies along c in each of the tunnels.

[Rupture of intracranial dermoid cyst with disseminated lipid droplets]. / Dissémination sous-arachnoïdienne de gouttelettes lipidiques par rupture d'un kyste dermoïde intracérébral.

INTRODUCTION: Dermoid cysts are rare slow-growing benign tumors of the central nervous system generally diagnosed in the third to fifth decade. They are formed from inclusion of ectodermal elements during neural tube closure, and are mostly located along the cranial or spinal midline axis. They cause many non specific symptoms such as headache and seizures, and may spontaneously rupture spreading fatty droplets into the ventricles and subarachnoid spaces. Rupture of dermoid cysts causes sequelae which may vary from no symptoms to death. In general, subtotal surgical removal is required for ruptured dermoid cysts. CASE REPORTS: We report two cases of ruptured intracranial dermoid tumor with non-specific clinical presentations. The first rupture was asymptomatic and discovered on brain magnetic resonance imaging (MRI) performed for other purposes. The second case was identified on brain imaging performed because of daily headache. These dermoid cysts were not surgically treated. Surveillance was advised because of the spontaneously favourable outcome observed in both cases. CONCLUSION: Surgical removal is not the only treatment of ruptured dermoid cyst. Monitoring with brain MRI can be sufficient if the rupture has no severe clinical impact.

[Leptomeningeal dissemination after ethmoidal sinus adenocarcinoma surgery: a rare complication]. / Dissémination leptoméningée après chirurgie d'un adénocarcinome de l'ethmoïde.

INTRODUCTION: Although rare, adenocarcinoma is the most frequent neoplasm of the ethmoid sinus and must be regarded as an occupational disease secondary to chronic wood dust exposure. Few cases with neurological metastasis have been reported. CASE REPORT: We report the cases of two patients who developed a multiple cranial nerve disorder for the first case and a cauda equina syndrome for the second, after ethmoid adenocarcinoma surgery. CONCLUSION: Diagnosis of carcinomatous meningitis is difficult and is based on clinical data, CSF analysis and gadolinium-enhanced T1-weighted brain and spinal cord MRI. The implication of surgery is discussed. Prognosis of such a disorder is poor.

Structural investigations of recently discovered high Tc superconductors.

A short overview is given of the possibilities of electron microscopy in the determination of the local, atomic scale structure of high Tc superconducting materials. Examples include the detection of weak oxygen ordering, description and characterization of deformation modulations in layered superconductors, and analysis of very long period superstructures. The ordering principles for tetrahedral chains in Ga-, Co-, or Al-substituted YBCO are discussed and their complex defect structures are described. The incommensurate modulation in YBCO-based materials containing SO4-tetrahedra, centered on the Cu(1) sites of the CuO-chain plane, is attributed to the ordering of b-oriented SO4-rich chains in the Cu(1)-S-O layer; the structure is described in terms of an SO4-concentration wave. As examples of the new mercury-based superconducting family we discuss Y0.6Ca0.4Ba2Hg1-xMxCu2O6+y, which crystallizes in the space group P4/mmm with a = 0.3870(1) nm, c = 1.2537(1) nm. This cuprate belongs to the 1212 series; susceptibility measurements show a Tc (onset) of 90K, with a diamagnetic volume fraction of 27% at 4.2K to be reached. A second example is related to the compound Tl2HgBa4Cu2O10+y, in which ordering between single Hg layers and double Tl layers is observed.

A five-dimensional structural investigation of the misfit layer compound

The structure of the misfit layer compound [Bi0.87SrO2]2[CoO2]1.82, bismuth strontium cobaltite, was determined by single-crystal X-ray diffraction using the five-dimensional superspace-group formalism. This composite crystal, of monoclinic symmetry, is composed of two subsystems exhibiting incommensurate periodicities along b, the binary axis direction. The first composite part [Bi0.87SrO2] displays an intrinsic modulation of planar monoclinic type characterized by the wavevector q* = 0.293a* + 0.915c*. The second composite part [CoO2] shows two different centered lattice variants. The structure of the misfit layer crystal can be described as an alternation along c of distorted rock-salt-type slabs, formed from [BiO] and [SrO] layers (first subsystem), and of [CoO2] layers (second subsystem) displaying a distorted CdI2-type structure. Two main structural results are obtained. First, as a consequence of the intrinsic modulation, disordered zones, characterized by Bi vacancies, are regularly distributed in the [BiO] layers. Second, strong chemical bonds are implied between the strontium atoms of the first subsystem and the oxygen atoms of the second one.

Cluster configurations in modulated EuVxMo8+/-yO14 crystals.

Three orthorhombic crystals of chemical formula Eu(x)V(y)Mo(8+/-z)O(14) were investigated by X-ray diffraction (Mo Kalpha radiation, lambda = 0.71073 Å). They have nearly the same lattice parameters (a approximately 11.3, b approximately 10.0, c approximately 9.2 Å), display one-dimensional incommensurate modulations of wavevector q* = gammac* and are characterized by the same superspace group Cmca(00gamma)s00. The crystals differ both in their compositions (namely Eu(0.976(6))V(1.13(5))Mo(7.10(5))O(14), Eu(0.986(4))V(1.10(3))Mo(7.30(1))O(14) and EuMo(7.96(1))O(14)) and in their gamma components [0.195 (2), 0.245 (2) and 0.286 (3), respectively]. The average structures of these crystals appear closely related to the structures of LaMo(7.7)O(14) (not modulated) and LaMo(8)O(14) (modulated); however, two main differences are outlined: first, the modulation direction is c in the Eu-containing crystals but b in the modulated La-containing crystal [q* = (1/3)b*], second, the Eu-containing crystals have centrosymmetric structures while the La-containing crystals have polar structures (space group C2ca). The Mo (or Mo and V) atoms are stacked to form (001) layers of metallic clusters. The density modulation of these structures implies the existence of the new types of clusters Mo(9), Mo(10), Mo(6)V(4), Mo(7)V(3) and Mo(8)V(2) besides the clusters M(8) (Mo(8), Mo(6)V(2) and Mo(7)V) and M(7) (Mo(7) and Mo(6)V) which are already known. Mo(8) units with cis and trans configurations and Mo(6)V(2) units with a trans configuration appear as the main cluster types in these crystals. The nature of the metallic clusters changes along c, but inside one (001) layer it is likely that only one cluster type with a given configuration is present. The main structural result is the formation, in some unit cells, of strong intercluster Mo-Mo, Mo-V or V-V bonds with distances close to 2.6 Å within a layer as well as between two neighbouring layers.

Nanoblock coupling effect in iodine intercalated [Bi(0.82)CaO(2)](2)[CoO(2)](1.69) layered cobaltite.

We report on the structural, microstructural, and electronic properties of iodine intercalated [Bi0.82CaO2]2[CoO2]1.69 misfit cobaltite. We first prove through a detailed and careful structural study that the block layer structure can be modified in the desired way. Iodine enters the material between the [BiO] double layers, and the c-cell parameter of the pristine compound is elongated by 3.6 Angstrom. On the basis of this result, we point out the coupling between the block-layer structure and the transport properties. Additionally, we provide in-depth commentary and discussion of some extra results, clarifying some doping effects in the quasi-2D studied phase. Finally, we also propose some expressions that might be useful to material scientists for the tuning of the properties of such compounds.

A novel layered titanoniobate LiTiNbO5: topotactic synthesis and electrochemistry versus lithium.

A new layered titanoniobate, LiTiNbO5, an n = 2 member of the A(x)M(2n)O(4n+2) family, has been synthesized using a molten salt reaction between HTiNbO5 and an eutectic "LiOH/LiNO3". This compound crystallizes in the P2(1)/m space group with a = 6.41 A, b = 3.77 A, c = 8.08 A, and beta = 92 degrees . It exhibits |TiNbO5|(infinity) layers similar to HTiNbO5, but differs from the latter by a "parallel configuration" of its |TiNbO6|(infinity) ribbons between the two successive layers. The topotactic character of the reaction suggests that exfoliation plays a prominent role in the synthesis of this new form. This new phase intercalates reversibly 0.8 lithium through a first-order transformation leading to a capacity of 94 mAh/g at a potential of 1.67 V vs Li/Li+.