Long-term worsening of different body functions in persons with progressive multiple sclerosis

Background: It is unclear whether EDSS is responsive to disability worsening in advanced MS. Objective: To explore the dynamics of disability worsening in persons with advanced-stage MS (EDSS ≥5.5) using three disability worsening definitions (EDSS, Rivermead Mobility Index (RMI), 9-Hole Peg Test (9-HPT)). Methods: EDSS-, RMI- and 9-HPT-based disability worsening were assessed over a minimum of two years in a cohort of 286 persons with advanced MS attending inpatient rehabilitation using Kaplan-Meier Curves and multivariable Cox regression. Furthermore, the correspondence between EDSS-, RMI- and 9-HPT-based disability worsening was analyzed. Results: Disability progression was observed in 49% (9-HPT), 52% (EDSS) and 53% (RMI), with 9-HPT-based worsening slightly lagging behind. The Multiple Sclerosis Severity Score (MSSS) was the only consistent factor predicting disability worsening based on all three definitions (EDSS: hazard ratio 1.48 [1.30;1.68]; RMI: 1.12 [0.99;1.27]; 9-HPT: 1.36 [1.18;1.57]). Correspondence between EDSS and the other definitions (9-HPT and RMI) was 44.3% and 55.7% at time of EDSS progression and 65.1% and 72.5% overall, respectively. Conclusion: In persons with advanced-stage MS, half still developed disability worsening in different functional systems over a median of 6 years. MSSS seems a valid predictor for disability worsening in all three outcome measures in advanced MS

Recommended outcome measures for inpatient rehabilitation of multiple sclerosis are not appropriate for the patients with substantially impaired mobility

BACKGROUND In multiple sclerosis (MS) rehabilitation, most currently used outcome measures were validated in patients with a relapsing remitting MS and mild to moderate impairments. We aimed to assess whether these measures were also adequate in more impaired patients, frequently encountered in those with progressive MS (PMS). METHODS Outcome measurements were extracted from medical records of 229 patients with PMS undergoing 3 weeks of routine inpatient rehabilitation between 2011 and 2015. We assessed the acceptability of Nine-Hole Peg Test (9HPT), Timed 25-Foot Walk (T25FW), 2-Minute Walk Test (2MWT), Rivermead Mobility Index (RMI) and the Functional Independence Measure (FIM) by analysing their statistical distributions, concurrent validity by comparing Spearman correlations with pre-specified hypotheses, and responsiveness across impairment status by calculating standardized response means. RESULTS Our concurrent validity hypotheses were mainly satisfied. However, all outcome measures had skewed distributions, showed low variability, and thus were inadequately discriminative. Moreover, 9HPT was never responsive across the impairment states, whereas the T25FW was responsive for mildly impaired patients, and the 2MWT for mild to moderate MS, respectively. Generic multi-items measures such as RMI and FIM-motor were adequately responsive for all severity levels. CONCLUSIONS Currently used outcome measures are inadequate for patients with impaired mobility, and there is a dire need of specifically designed outcome measures for routine care that are less burdensome and short-term responsive

Thermal stability and thermoelectric properties of CuxAs40−xTe60−ySey semiconducting glasses

International audienceWe report on the thermal behavior and thermoelectric properties of bulk chalcogenide glasses in the systems CuxAs40−xTe60 (20≤x≤32.5) and CuxAs40−xTe60−ySey, (0≤y≤9) synthesized by conventional melt-quenching techniques. The thermal stability of these glasses was probed by differential scanning calorimetry to determine the characteristic Tg and ΔT temperatures, both of which increasing noticeably with y. Thermoelectric properties were found to be mainly influenced by the Cu concentration with respect to the Se content. The thermal conductivity is practically composition-independent throughout the compositional range covered. A maximum ZT value of 0.02 at 300K increasing to 0.06 at 375K was achieved for the composition Cu30As10Te54Se6

Fast and scalable preparation of tetrahedrite for thermoelectrics via glass crystallization

International audienceA Cu12Sb3.6Bi0.4S10Se3 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 (~200º 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 Cu12Sb4S13, with a maximum power factor of ~400 mW/K2m at room temperature

Electronic structure, low-temperature transport and thermodynamic properties of polymorphic b-As2Te3

International audienceb-As2Te3 belongs to the prominent family of Bi2Te3-based materials, which show excellent thermoelectric properties near room temperature. In this study, we report a joint theoretical and experimental investigation of its electronic and thermal properties at low temperatures (5-300 K). These results are complemented by specific heat measurements (1.8-300 K) that provide further experimental evidence of the first order latticedistortion undergone by b-As2Te3 near 190 K. Data taken on cooling and heating across this transition show that the lattice distortion has little influence on the electronic properties and further evidence a weak hysteretic behavior. Although first-principles calculations predict a semiconducting ground state, these measurements show that b-As2Te3 behaves as a degenerate p-type semiconductor with a high carrierconcentration of 1020 cm-3 at 300 K likely due to intrinsic defects. Calculations of the vibrational properties indicate that the extremely low lattice thermal conductivity values (0.8 W m-1 K-1 at 300 K) mainly originate from low-energy Te optical modes that limit the energy window of the acousticbranches. This limited ability to transport heat combined with a relatively large band gap suggest that high thermoelectric efficiency could be achieved in this compound when appropriately doped

Polymorphism in Thermoelectric As2Te3

International audienceMetastable β-As2Te3 (R3̅m, a = 4.047 Å and c =29.492 Å at 300 K) is isostructural to layered Bi2Te3 and is known for similarly displaying good thermoelectric properties around 400 K. Crystallizing glassy-As2Te3 leads to multiphase samples, while β-As2Te3 could indeed be synthesized with good phase purity (97%) by melt quenching. As expected, β-As2Te3 reconstructively transforms into stable α-As2Te3 (C2/m, a = 14.337 Å, b = 4.015 Å, c = 9.887 Å, and β = 95.06°) at 480 K. This β → α transformation can be seen as the displacement of part of the As atoms from their As2Te3 layers into the van der Waals bonding interspace. Upon cooling, β-As2Te3 displacively transforms in two steps below TS1 = 205−210 K and TS2 = 193−197 K into a new β′ As2Te3 allotrope. These reversible and first-order phase transitions give rise to anomalies in the resistance and in the calorimetry measurements. The new monoclinic β′-As2Te3 crystal structure (P21/m, a = 6.982 Å, b = 16.187 Å, c = 10.232 Å, β = 103.46° at 20 K) was solved from Rietveld refinements of X-ray and neutron powder patterns collected at low temperatures. These analyses showed that the distortion undergone by β-As2Te3 is accompanied by a 4-fold modulation along its b axis. In agreement with our experimental results, electronic structure calculations indicate that all three structures are semiconducting with the α-phase being the most stable one and the β′-phase being more stable than the β-phase. These calculations also confirm the occurrence of a van der Waals interspace between covalently bonded As2Te3 layers in all three structures