Influence de la variété allotropique du polybutène 1 sur ses propriétés mécaniques statiques

L’étude des propriétés mécaniques statiques du polybutène 1 met en évidence l’influence de la variété cristalline sur les modules et fonctions de relaxation. Ces dernières seraient les résultantes de trois phénomènes principaux : relaxation de la forme II, relaxation de la forme I et transformation de II en I. La contrainte influe sur la vitesse de passage de la forme II en forme I et sur la valeur de leurs fonctions de relaxation

Comparative study on Charpy specimen reconstitution techniques

International audienceReconstitution techniques are often used to allow material from previously fractured Charpy-V specimens to be reused for additional experiments. This paper presents a comparative experimental study of various reconstitution techniques and evaluates the feasibility of these methods for future use in shielded cells. The following techniques were investigated: arc stud welding, 6.0 kW CO2 continuous wave laser welding, 4.5 kW YAG continuous wave laser welding and friction welding. Subsize Charpy specimens were reconstituted using a 400 W YAG pulsed wave laser. The best result was obtained with arc stud welding; the resilience of the reconstituted specimens and the load-displacement curves agreed well with the reference specimens, and the temperature elevation caused by the welding process was limited to the vicinity of the weld. Good results were also obtained with friction welding; this process led to the best quality welds. Laser welding seems to have affected the central part of the specimens, thus leading to different resilience values and load-displacement curves

Pigments et production d'H

Les auteurs mettent en évidence le rôle de la catalase dans les propriétés radioprotectrices de l'hémocyanine et dans la cancérogenèse de la peau humaine. Ils montrent notamment comment l'application de pommade à la catalase a stoppé révolution cancéreuse d'enfants atteints de Xeroderma Pigmentosum (XP). Bien que les résultats cliniques et biologiques ne permettent pas encore une conclusion catégorique, ils soulignent le fait qu'une insuffisance de l'activité catalatique pourrait constituer un facteur important dans le développement de XP et qu'à l'inverse une activité catalatique puissante pourrait représenter un facteur non négligeable dans la radiorésistance élevée du scorpion

Towards Optimized Care After Bariatric Surgery by Physical Activity and Exercise Intervention: a Review

Although there is growing evidence on the importance of physical activity and exercise intervention after bariatric surgery, it remains to be clarified as to why and how post-operative exercise intervention should be implemented. In this narrative and practically oriented review, it is explained why exercise interventions and physical activity are important after bariatric surgery, how to prescribe exercise and monitor physical activity and how and when physical fitness, muscle strength, fat (-free) mass and bone mineral density could be assessed during follow-up. It is suggested that the inclusion of physical activity and exercise training in the clinical follow-up trajectory could be of great benefit to bariatric surgery patients, since it leads to greater improvements in body composition, bone mineral density, muscle strength and physical fitness.status: publishe

Predictors of Parenchymal Hematoma After Mechanical Thrombectomy

International audienceBackground and Purpose— Parenchymal hematoma (PH) is a rare but dreadful complication of acute ischemic stroke with unclear underlying mechanisms. We aimed to study the incidence and predictors of PH after mechanical thrombectomy. Methods— Data from a prospective observational multicenter registry was screened to identify acute ischemic stroke patients with an anterior circulation large vessel occlusion who underwent mechanical thrombectomy. Clinical, imaging, and procedural characteristics were used for the analysis, including brain imaging systematically performed at 24 hours. PH occurrence was assessed according to ECASS (European Collaborative Acute Stroke Study) criteria. Univariate and multivariable analyses were performed to identify predictors of PH. Results— A total of 1316 patients were included in the study. PH occurred in 153 out of 1316 patients (11.6%) and was associated with a lower rate of favorable outcome and increased mortality. On multivariable analysis, age (per 1 year increase, odds ratio [OR], 1.01; 95% CI, 1.00–1.03; P =0.05), current smoking (OR, 2.02; 95% CI, 1.32–3.09; P <0.01), admission Alberta Stroke Program Early CT Score (per a decrease of 1 point, OR, 1.70; 95% CI, 1.18–2.44; P <0.01), general anesthesia (OR, 1.98; 95% CI, 1.36–2.90; P <0.001), angiographic poor collaterals (OR, 2.13; 95% CI, 1.36–3.33; P <0.001) and embolization in new territory (OR, 2.94; 95% CI, 1.70–5.10; P <0.001) were identified as independent predictors of PH. Conclusions— PH occurred at a rate of 11.6% after mechanical thrombectomy, with high morbidity and mortality. Our study identified clinical, radiological, and procedural predictors of PH occurrence that can serve as the focus of future periprocedural management studies with the aim of reducing its occurrence. Clinical Trial Registration— URL: https://www.clinicaltrials.gov . Unique identifier: NCT03776877

Post-Thrombolysis Recanalization in Stroke Referrals for Thrombectomy

International audienceBackground and Purpose—Whether all acute stroke patients with large vessel occlusion need to undergo intravenous thrombolysis before mechanical thrombectomy (MT) is debated as (1) the incidence of post-thrombolysis early recanalization (ER) is still unclear; (2) thrombolysis may be harmful in patients unlikely to recanalize; and, conversely, (3) transfer for MT may be unnecessary in patients highly likely to recanalize. Here, we determined the incidence and predictors of post-thrombolysis ER in patients referred for MT and derive ER prediction scores for trial design. Methods—Registries from 4 MT-capable centers gathering patients referred for MT and thrombolyzed either on site (mothership) or in a non MT-capable center (drip-and-ship) after magnetic resonance– or computed tomography–based imaging between 2015 and 2017. ER was identified on either first angiographic run or noninvasive imaging. In the magnetic resonance imaging subsample, thrombus length was determined on T2*-based susceptibility vessel sign. Independent predictors of no- ER were identified using multivariable logistic regression models, and scores were developed according to the magnitude of regression coefficients. Similar registries from 4 additional MT-capable centers were used as validation cohort. Results—In the derivation cohort (N=633), ER incidence was ≈20%. In patients with susceptibility vessel sign (n=498), no-ER was independently predicted by long thrombus, proximal occlusion, and mothership paradigm. A 6-point score derived from these variables showed strong discriminative power for no-ER (C statistic, 0.854) and was replicated in the validation cohort (n=353; C statistic, 0.888). A second score derived from the whole sample (including negative T2* or computed tomography–based imaging) also showed good discriminative power and was similarly validated. Highest grades on both scores predicted no-ER with >90% specificity, whereas low grades did not reliably predict ER. Conclusions—The substantial ER rate underlines the benefits derived from thrombolysis in bridging populations. Both prediction scores afforded high specificity for no-ER, but not for ER, which has implications for trial design