Mélanges de polymères à gouttes composites : application recyclage

RÉSUMÉ Cette étude aborde deux axes de recherche. Le premier traite du recyclage des mélanges de polymères et constitue le pilier principal de ce projet. Le deuxième axe effectue l’analyse de l’effet de la viscoélasticité et des forces interfaciales sur l’établissement du mouillage dans les systèmes ternaires HDPE/PP/PS et HDPE/PP/PC. Le recyclage des mélanges de plastiques de compositions différentes a été limité par le fait que les polymères forment des phases immiscibles démontrant une faible compatibilité et adhésion interfaciale. Pourtant, les produits de consommation impliquent de plus en plus de systèmes complexes (résines d’ingénierie, mélanges) et le procédé de séparation devient difficile et même parfois impossible. Le problème relié au recyclage des mélanges de polymères est principalement dû au fait de la présence de plusieurs interfaces, dont chacune est potentiellement une zone de fragilité mécanique. Ceci a pour effet de générer de faibles propriétés mécaniques. Chaque interface nécessite son agent interfacial et le coût global de compatibilisation d’un système multi composants peut devenir coûteux. Ici, un concept nouveau est employé où une ségrégation contrôlée des phases non recyclables est réalisée dans l’une des deux phases majeures : le polyéthylène de haute densité (HDPE) et le polypropylène (PP). En se basant sur un mélange co-continu HDPE/PP, un système à cinq phases constitué du HDPE, PP, PS, PMMA et PC est préparé. Des gouttes composites PS/PMMA/PC sont générées exclusivement dans la phase de PP lorsque l’interface HDPE/PP est compatibilisée. Cette approche réduit le problème d’un système présentant plusieurs interfaces à une seule interface dominante HDPE/PP qui peut être par la suite compatibilisée en employant un copolymère pratique. Les interfaces secondaires relèvent d’un rôle mineur dans la structure de goutte composite. La caractérisation par MEB combinée à l’emploi de recuits statiques permet de mettre clairement en évidence la microstructure du système. Le triplet PS/PMMA/PC forme des gouttes composites où le PS encapsule le PMMA qui enveloppe à son tour le polycarbonate. Ceci est un processus thermodynamique contrôlé par la théorie d’encapsulation et est apparemment indépendant de l’étape de mélange (mélangeur interne ou extrusion/injection). Puisque le système HDPE/PP correspond à la tension interfaciale minimale dans la littérature, cette approche est très robuste et serait applicable à un vaste spectre de résines. L’ordonnancement des phases est spontané lorsqu’un compatibilisant EPDM est utilisé en provoquant la ségrégation complète des gouttes composites PS/PMMA/PC dans la phase de polypropylène. De plus, les propriétés mécaniques de telles structures sont très bonnes en termes de module et de résistance à la traction. En employant les conditions de mélange adaptées lors de l’injection, un matériau ductile avec un bon allongement à la rupture peut être obtenu. Cette approche pourrait être d’une importance significative dans le milieu industriel du recyclage.----------ABSTRACT This study investigates two axis of research. The first one is about comingled plastic recycling and constitute the core of this project whereas a second and more fundamental work analyzes the effect of viscoelasticity and interfacial driven forces on ternary polymer blends wetting. The recycling of multiple plastics of different composition has been limited by the fact that plastics form immiscible phases with poor compatibility and interfacial adhesion. Due to the complexity of new plastic products which involve speciality resins and polymer blends, the separation process can be costly and recycling sometimes impossible. The problem of recycling co-mingled plastics is principally related to the problem of multiple interfaces in multicomponent immiscible polymer blends. Those interfaces present a locus for failure and hence very poor mechanical properties. Multiple interfaces require multiple interfacial modifiers and the cost becomes prohibitive. Here we study a new concept where controlled polymer segregation is used to locate multiple non-recyclable phases within one of two major phases: high density polyethylene (HDPE) and polypropylene (PP). Starting from a co-continuous blend of HDPE and PP, a multiple 5 component system comprised of HDPE, PP, PS, PMMA and PC is prepared in which PS/PMMA/PC composite droplets are all exclusively located within PP when the HDPE/PP interface is compatibilized. This approach reduces the problem of multiple interfaces to one principal interface (HDPE/PP) which can be compatibilized. The other interfaces are relegated minor roles as parts of the composite droplet system. From SEM characterization and annealing procedures, it can be clearly seen from this work that the PS/PMMA/PC forms a hierarchical structure where PS encapsulates PMMA which in turn engulfs the PC. This is a thermodynamically driven process which is controlled by spreading theory and appears to be independent of the blending process (internal mixing-extrusion/injection). Since a compatibilized HDPE/PP system presents one of the lowest interfacial tensions in the immiscible polymer literature, this approach is highly robust and would be applicable to a wide range of plastics. The approach is highly robust since the system segregates and assembles spontaneously: the compatibilizer for the HDPE/PP interface drives specifically to that interface while the composite droplet comprised of all other polymeric moieties assembles in an ordered fashion exclusively within the PP phase. Moreover, the tensile mechanical properties of the structures prepared above demonstrate very good and even improved tensile strength and modulus. Using the appropriate processing conditions, ductile materials with good elongation at break can also be achieved. This approach could lead to promising industrial applications for mixed plastic waste

Nodular Fasciitis with Cortical Erosion of the Hand

Nodular fasciitis is a benign, reactive myofibroblastic tumor that is often mistaken for a sarcoma because of its histological appearance and rapid growth. Involvement of a finger is extremely rare. We report a case of nodular fasciitis of the thumb, accompanied by bone erosion. Magnetic resonance findings suggested the possibility of a malignancy, which could have led to misdiagnosis as a malignant soft tissue sarcoma. Instead, the lesion was treated by excisional biopsy, which confirmed nodular fasciitis. There has been no evidence of local recurrence at recent follow-up, 1 year after surgery. This case illustrates that, to avoid unnecessarily aggressive surgery, nodular fasciitis must be included in the differential diagnosis for any finger lesion that resembles a sarcoma, even if bone erosion is present

Growth hormone level at admission and its evolution during refeeding are predictive of short-term outcome in restrictive anorexia nervosa

International audienceThe growth hormone (GH)– insulin-like growth factor-1 (IGF-1) axis is dramatically altered in patients with anorexia nervosa (AN). The aim of the present study was to investigate whether GH and IGF-1 could be predictors of outcome in patients with a restrictive form of AN. Blood levels of GH, IGF-1, adipocytokines, ghrelin, insulin, glucose, and sex and thyroid hormones were measured in eleven women inpa-tients with AN and in ten healthy women controls. Three stages were compared during refeeding: admission (T0), when BMI reached 16 kg/m 2 (T1) and at discharge when BMI reached 17·5 kg/m 2 (T2). Clinical status was assessed 6 months after discharge from hospital (T3), and remission was defined by the maintenance of a BMI $ 17·5 kg/

Etude expérimentale de la rupture ostéoporotique du col fémoral

L'ostéoporose est une maladie qui affaiblit la structure de l'os par la détérioration de l'architecture trabéculaire et par la diminution de l'épaisseur corticale et l'augmentation de sa porosité. Malgré le coût de santé public, son dépistage n'est pas systématique, et n'est basé que sur l'évaluation de la minéralisation d'un volume osseux à partir de sa projection plane. Aucune information directe sur la structure n'est donnée. Dans le but d'étudier la contribution de la structure osseuse dans la résistance de la partie proximale du fémur, un protocole expérimental simulant la phase d'appui monopodal de la marche, a été développé. Ces essais ont permis de mesurer l'effort à la rupture nécessaire pour provoquer des fractures au niveau du col fémoral semblables aux observations cliniques. Les résultats expérimentaux, serviront à développer un modèle numérique basé sur la théorie des poutres, pour étudier la contribution de l'enveloppe cortical et des faisceaux trabéculaires dans la résistance de la partie proximale du fémur

Unacylated Ghrelin is associated with the isolated low HDL-cholesterol obese phenotype independently of insulin resistance and CRP level

<p>Abstract</p> <p>Background</p> <p>Low plasma high-density lipoprotein-cholesterol (HDL-c) level is commonly present in obesity and represents an independent cardiovascular risk factor. However, obese patients are a very heterogeneous population and the factors and mechanisms that contribute to low HDL-c remain unclear. The aim of this study was to investigate the association between plasma HDL-c levels and plasma hormonal profiles (insulin, adiponectin, resistin, leptin and ghrelin) in subsets of class II and III obese patients.</p> <p>Methods</p> <p>Fasting plasma levels of glucose, total cholesterol, LDL-c, HDL-c, triglycerides, free fatty acids, apoproteins A-I, B-100, B-48, C-II, C-III, insulin, hs-CRP, adipocytokines (adiponectin, resistin, leptin), unacylated ghrelin, body composition (DXA) and resting energy expenditure were measured in three subsets of obese patients: 17 metabolically abnormal obese (MAO) with metabolic syndrome and the typical metabolic dyslipidaemia, 21 metabolically healthy obese (MHO) without metabolic syndrome and with a normal lipid profile, and 21 isolated low HDL-c obese patients (LHO) without metabolic syndrome, compared to 21 healthy lean control subjects.</p> <p>Results</p> <p>Insulin resistance (HOMA-IR) increased gradually from MHO to LHO and from LHO to MAO patients (<it>p </it>< 0.05 between MHO and MAO and between LHO and MAO). In multiple regression analysis, serum unacylated ghrelin levels were only positively and independently associated with HDL-c levels in the LHO group (<it>p </it>= 0.032).</p> <p>Conclusions</p> <p>These results suggest that, in class II and III obese patients with an isolated low HDL-c phenotype, unacylated ghrelin is positively associated with HDL-c level independently of insulin resistance and CRP levels, and may contribute to the highly prevalent low HDL-c level seen in obesity.</p

A prospective study of shoulder pain in primary care: Prevalence of imaged pathology and response to guided diagnostic blocks

<p>Abstract</p> <p>Background</p> <p>The prevalence of imaged pathology in primary care has received little attention and the relevance of identified pathology to symptoms remains unclear. This paper reports the prevalence of imaged pathology and the association between pathology and response to diagnostic blocks into the subacromial bursa (SAB), acromioclavicular joint (ACJ) and glenohumeral joint (GHJ).</p> <p>Methods</p> <p>Consecutive patients with shoulder pain recruited from primary care underwent standardised x-ray, diagnostic ultrasound scan and diagnostic injections of local anaesthetic into the SAB and ACJ. Subjects who reported less than 80% reduction in pain following either of these injections were referred for a magnetic resonance arthrogram (MRA) and GHJ diagnostic block. Differences in proportions of positive and negative imaging findings in the anaesthetic response groups were assessed using Fishers test and odds ratios were calculated a for positive anaesthetic response (PAR) to diagnostic blocks.</p> <p>Results</p> <p>In the 208 subjects recruited, the rotator cuff and SAB displayed the highest prevalence of pathology on both ultrasound (50% and 31% respectively) and MRA (65% and 76% respectively). The prevalence of PAR following SAB injection was 34% and ACJ injection 14%. Of the 59% reporting a negative anaesthetic response (NAR) for both of these injections, 16% demonstrated a PAR to GHJ injection. A full thickness tear of supraspinatus on ultrasound was associated with PAR to SAB injection (OR 5.02; <it>p </it>< 0.05). Ultrasound evidence of a biceps tendon sheath effusion (OR 8.0; <it>p </it>< 0.01) and an intact rotator cuff (OR 1.3; <it>p </it>< 0.05) were associated with PAR to GHJ injection. No imaging findings were strongly associated with PAR to ACJ injection (<it>p </it>≤ 0.05).</p> <p>Conclusions</p> <p>Rotator cuff and SAB pathology were the most common findings on ultrasound and MRA. Evidence of a full thickness supraspinatus tear was associated with symptoms arising from the subacromial region, and a biceps tendon sheath effusion and an intact rotator cuff were associated with an intra-articular GHJ pain source. When combined with clinical information, these results may help guide diagnostic decision making in primary care.</p

Notch pathway inhibition targets chemoresistant insulinoma cancer stem cells

Insulinomas (INS) are the most common neuroendocrine pancreatic tumours in humans and dogs. The long-term prognosis for malignant INS is still poor due to a low success rate of the current treatment modalities, particularly chemotherapy. A better understanding of the molecular processes underlying the development and progression of INS is required to develop novel targeted therapies. Cancer stem cells (CSCs) are thought to be critical for the engraftment and chemoresistance of many tumours, including INS. This study was aimed to characterise and target INS CSCs in order to develop novel targeted therapies. Highly invasive and tumourigenic human and canine INS CSC-like cells were successfully isolated. These cells expressed stem cell markers (OCT4, SOX9, SOX2, CD133 and CD34), exhibited greater resistance to 5-fluorouracil (5-FU), and demonstrated a more invasive and tumourigenic phenotype in vivo compared to non-CSCs. Here, we demonstrated that Notch-signalling-related genes (NOTCH2 and HES1) were overexpressed in INS CSC-like cells. Protein analysis showed an active NOTCH2-HES1 signalling in INS cell lines, especially in cells resistant to 5-FU. Inhibition of the Notch pathway, using a gamma secretase inhibitor (GSI), enhanced the sensitivity of INS CSC-like cells to 5-FU. When used in combination GSI and 5-FU, the clonogenicity in vitro and the tumourigenicity in vivo of INS CSC-like cells were significantly reduced. These findings suggested that the combined strategy of Notch signalling inhibition and 5-FU synergistically attenuated enriched INS CSC populations, providing a rationale for future therapeutic exploitation

Magnetic resonance imaging, magnetic resonance arthrography and ultrasonography for assessing rotator cuff tears in people with shoulder pain for whom surgery is being considered

Background Shoulder pain is a very common symptom. Disorders of the rotator cuff tendons due to wear or tear are among the most common causes of shoulder pain and disability. Magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA) and ultrasound (US) are increasingly being used to assess the presence and size of rotator cuff tears to assist in planning surgical treatment. It is not known whether one imaging method is superior to any of the others.Objectives To compare the diagnostic test accuracy of MRI, MRA and US for detecting any rotator cuff tears (i.e. partial or full thickness) in people with suspected rotator cuff tears for whom surgery is being considered.Search methods We searched the Cochrane Register of Diagnostic Test Accuracy Studies, MEDLINE, EMBASE, and LILACS from inception to February 2011. We also searched trial registers, conference proceedings and reference lists of articles to identify additional studies. No language or publication restrictions were applied.Selection criteria We included all prospective diagnostic accuracy studies that assessed MRI, MRA or US against arthroscopy or open surgery as the reference standard, in people suspected of having a partial or full thickness rotator cuff tear. We excluded studies that selected a healthy control group, or participants who had been previously diagnosed with other specific causes of shoulder pain such as osteoarthritis or rheumatoid arthritis. Studies with an excessively long period (a year or longer) between the index and reference tests were also excluded.Data collection and analysis Two review authors independently extracted data on study characteristics and results of included studies, and performed quality assessment according to QUADAS criteria. Our unit of analysis was the shoulder. for each test, estimates of sensitivity and specificity from each study were plotted in ROC space and forest plots were constructed for visual examination of variation in test accuracy. Meta-analyses were performed using the bivariate model to produce summary estimates of sensitivity and specificity. We were unable to formally investigate potential sources of heterogeneity because of the small number of studies.Main results We included 20 studies of people with suspected rotator cuff tears (1147 shoulders), of which six evaluated MRI and US (252 shoulders), or MRA and US (127 shoulders) in the same people. Many studies had design flaws, with the potential for bias, thus limiting the reliability of their findings. Overall, the methodological quality of the studies was judged to be low or unclear. for each test, we observed considerable heterogeneity in study results, especially between studies that evaluated US for the detection of full thickness tears and studies that evaluated MRA for the detection of partial thickness tears. the criteria for a positive diagnostic test (index tests and reference standard) varied between studies.Meta-analyses were not possible for studies that assessed MRA for detection of any rotator cuff tears or partial thickness tears. We found no statistically significant differences in sensitivity or specificity between MRI and US for detecting any rotator cuff tears (P = 0.13), or for detecting partial thickness tears (P = 1.0). Similarly, for the comparison between MRI, MRA and US for detecting full thickness tears, there was no statistically significant difference in diagnostic performance (P = 0.7). for any rotator cuff tears, the summary sensitivity and specificity were 98% (95% CI 92% to 99%) and 79% (95% CI 68% to 87%) respectively for MRI (6 studies, 347 shoulders), and 91% (95% CI 83% to 95%) and 85% (95% CI 74% to 92%) respectively for US (13 studies, 854 shoulders). for full thickness tears, the summary sensitivity and specificity were 94% (95% CI 85% to 98%) and 93% (95% CI 83% to 97%) respectively for MRI (7 studies, 368 shoulders); 94% (95% CI 80% to 98%) and 92% (95% CI 83% to 97%) respectively for MRA (3 studies, 183 shoulders); and 92% (95% CI 82% to 96%) and 93% (95% CI 81% to 97%) respectively for US (10 studies, 729 shoulders).Because few studies were direct head-to-head comparisons, we could not perform meta-analyses restricted to these studies. the test comparisons for each of the three classifications of the target condition were therefore based on indirect comparisons which may be prone to bias due to confounding.Authors' conclusions MRI, MRA and US have good diagnostic accuracy and any of these tests could equally be used for detection of full thickness tears in people with shoulder pain for whom surgery is being considered. the diagnostic performance of MRI and US may be similar for detection of any rotator cuff tears. However, both MRI and US may have poor sensitivity for detecting partial thickness tears, and the sensitivity of US may be much lower than that of MRI. the strength of evidence for all test comparisons is limited because most studies were small, heterogeneous and methodologically flawed, and there were few comparative studies. Well designed studies that directly compare MRI, MRA and US for detection of rotator cuff tears are needed.Universidade Federal de São Paulo, BrazilParker Institute, DenmarkOak FoundationTeesside University, UKUniversidade Federal de São Paulo, Dept Orthopaed & Traumatol, BR-04038032 São Paulo, BrazilMonash Univ, Sch Publ Hlth & Prevent Med, Dept Epidemiol & Prevent Med, Monash Dept Clin Epidemiol,Cabrini Hosp, Malvern, AustraliaUniv Birmingham, Birmingham, W Midlands, EnglandUniv Teesside, Hlth & Social Care Inst, Middlesbrough, Cleveland, EnglandUniversidade Federal de São Paulo, Dept Orthopaed & Traumatol, BR-04038032 São Paulo, BrazilWeb of Scienc

Les droits des personnes victimes d’esclavage domestique : état des lieux

International audienc