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Resume Objectif Le but de cette etude etait d’evaluer l’interet et les effets adverses d’un triple bloc (femoral, sciatique, obturateur) pour la realisation d’arthroscopie de genou (meniscectomie) en ambulatoire. Patients et methodes Cette etude prospective monocentrique descriptive incluait, apres consentement eclaire, des patients adultes (ASA 1–3) operes sous tribloc. Les blocs etaient realises au creux inguinal pour les nerfs femoral et obturateur et a la fesse (nerf sciatique), avec de la lidocaine ou de la mepivacaine 1,5 % (30–40 ml) selon une technique classique de neurostimulation. En cas de bloc incomplet a 40 minutes ou la survenue d’une douleur peroperatoire, une conversion en anesthesie generale (AG) etait realisee. Un observateur independant colligeait les delais de prise en charge, les evenements per et postoperatoires (en salle post-interventionnelle, au centre ambulatoire, et a distance par appels a j1, j3, j7 et visite chirurgicale a un mois). Resultats Trois cent douze patients ont ete selectionnes pour 115 triblocs realises, car 157 patients ont choisi l’AG, 19 la rachianesthesie et 21 presentes une contre-indication a l’ALR. Sur les 115 triblocs, 12 (10 %) patients ont necessite une AG avant incision (echecs d’installation/realisation). Le delai entre le debut du bloc et l’installation chirurgicale etait de 40 (10–60) minutes. En peroperatoire, 12 echecs (12 %) etaient lies a une douleur chirurgicale ( n = 7, 7 %) ou au garrot ( n = 5, 5 %). L’equipe chirurgicale donnait une note globale de confort chirurgical de 90 (60–100). La duree de sejour en SSPI etait de 15 (5–60) minutes et les scores de douleur inferieurs a 30/100 pour tous les patients jusqu’a la sixieme heure (aucun recours morphinique). A j0, 2 echecs de sortie d’ambulatoire sont notes (sans rapport avec le bloc). Le taux de NVPO est de 3,5 % a j0 et 8 % a j1. Le taux de paresthesie residuel est 1,7 % a j1 et 0,8 % a J3. Aucun effet adverse a j7 et un mois n’etait signale. La satisfaction des patients etait elevee, car 91 % « souhaitent la meme anesthesie ». Conclusion Le tribloc est une technique adaptee a l’anesthesie ambulatoire pour meniscectomie de genou : passage rapide en SSPI, NVPO limitees, analgesie efficace, retour rapide au domicile. La principale cause d’echec est liee a l’installation incomplete du bloc (10 % des cas) necessitant une sedation complementaire ou une conversion en AG. Compte tenu du long delai de preparation, une salle de preinduction est souhaitable pour faciliter l’organisation du programme operatoire.

Synthesis of well-defined and highly thiol-end-functionalized polyethylene (PE-SH) was performed using olefin polymerization by coordination chemistry and robust functionalization chemistries. Using a Nd-based catalyst in combination with n-butyloctylmagnesium (BOMg), dipolyethylenylmagnesium compounds (PE-Mg-PE) were first prepared by catalyzed polyethylene chain growth on magnesium. Taking advantage of the reactivity of the carbon−magnesium bonds so formed, several functionalization strategies were assessed with the main aim of producing the targeted PE-SH in the simplest and most efficient way. In particular, polysulfurs and thiothiocarbonylated-end-functionalized polyethylenes were successfully obtained and reduced by lithium aluminum hydride (LiAlH4) to give the desired PE with up to 90% thiol chain end functionality.

A factorial design was used to understand how reaction parameters such as the monomer concentration, temperature, alkyl aluminium concentration, etc. influence the reaction rate and the polymer properties on two types of metallocene catalyst systems. The polymerisation kinetics and molecular weight distribution (MWD) obtained using a novel system (catalyst supported on an activated silica) were to those obtained with the reference system (same catalyst and silica but activated with MAO). As expected, the reaction temperature and the monomer concentration are the most important factors influencing the polymerisation rate, and this is independent of the catalytic system. Otherwise, the statistical approach allowed us to identify useful levels of MAO and comonomer at which to run in order to maximise the reaction rate.

The role of certain morphological properties of different silica used as supports for metallocene catalysts was investigated in order to quantify their eventual influence on the kinetics of ethylene polymerisation in heptane slurry, as well as on the polymer properties. It was shown that there is no clear link between porosity and observed activity with some highly porous silica producing relatively inactive supported catalysts. It was further shown that within a batch of silica, the particle size had a significant impact on observed kinetics. While it appears that there is possibly some diffusion resistance encountered in the larger particles, it was also shown that prolonged contact between the support and the alkylating agent could increase reaction rates in the larger particles.

Resume Le risque de developper une complication infectieuse apres ponction perimedullaire (meningite, abces) chez un patient febrile est rare (1/100 000). Des mecanismes moleculaires (cytokines, TNFα) et structurels ont ete identifies pour expliquer la fragilite de la barriere hematomeningee dans ce contexte. Les modifications de la barriere hematomeningees sont complexes et multiples, incluant l’alteration des transports transmembranaires (macromolecule, leuco- et lymphocytes), la dysfonction des molecules d’adhesions et la dysregulation des enzymes membranaires. Des facteurs favorisant l’infection ont ete identifies : absence d’antibiotherapie, forte bacteriemie, condition d’asepsie defectueuse, immunodepression (corticotherapie, infection, cancer, diabete sucre), rachiperidurale combinee, ponctions multiples… En cas de benefice peu evident en faveur de l’anesthesie locoregionale (ALR) et de signes cliniques infectieux (fievre, frisson) et d’absence d’antibiotherapie efficace, l’abstention est recommandee. A l’inverse, une ponction (sans catheter) est acceptable chez un patient sous antibiotherapie efficace avant la ponction et qui a presente une reponse a ce traitement. Si une reactivation du Herpes simplex (HSV) est frequente apres injection d’opiaces en perimedullaire, elle ne la contre-indique pas avec les anesthesiques locaux (AL). Une surveillance clinique etroite et prolongee postponction doit etre realisee car le retard de traitement d’une complication (meningite) aggrave le pronostic fonctionnel. La suspicion de meningite au decours de la ponction est une urgence diagnostique et therapeutique (antibiotherapie probabiliste immediate).

We conducted this prospective randomized study to compare the success rate and the onset time between 3 intensities of stimulation threshold (0.5, 0.5-0.64, and 0.65-0.8 mA) when using a peripheral nerve stimulation at the midhumeral level.Sixty-nine adult patients undergoing elective hand surgery were studied. Blocks were performed using conventional nerve stimulation technique. Needle advance began at 2 mA (1 Hz, 0.1 millisecond). When motor response (MR) occurred at less than 0.5 mA, needle position was fixed for "group0.5 mA." For "group 0.5-0.64 mA," the needle was withdrawn until MR occurred at greater than 0.5 mA and disappeared at less than 0.5 mA. For "group0.65 mA," the needle was withdrawn until MR occurred at greater than 0.65 mA and disappeared at less than 0.65 mA. For each group, patients received 8 mL of ropivacaine 7.5 mg/mL on the 4 nerves (radial, median, ulnar, and musculocutaneous). Primary end point was the number of failed radial nerve sensory blocks at 30 mins.The time to perform the block was not different between the 3 groups (17 mins [SD, 7 mins] vs 13 mins [SD, 8 mins] and 13 mins [SD, 4 mins], respectively). The time required to obtain a complete sensory block was shorter for the 4 nerves in group0.5 mA, with a statistical significance for radial and musculocutaneous nerves in group0.5 mA versus group 0.5-0.64 mA and group0.65 mA. Patients in group0.5 mA had a greater success rate for complete sensory radial nerve compared with those of group 0.5-0.64 mA and group0.65 mA at any interval times between 5 and 30 mins (P = 0.0001). Supplemental local anesthesia was provided for the 3 groups more frequently for the median nerve, with no difference between groups. Group0.65 mA required 5 general anesthesias (20%) as compared with 1 (4%) in group0.5 mA (P0.05). No adverse event (dysesthesia) occurred after 48 hrs and 45 days.We conclude that intensity of stimulation influenced onset time and success rate.

Metallocene borohydride complexes {(Me2Si(C13H8)2)Nd(μ-BH4)[(μ-BH4)Li(THF)]}2 (1) and (Me2Si(2,7-tBu2C13H6)2)Nd(BH4)(μ-BH4)Li(ether)3 (2) were prepared by reaction of the dilithium salts of silylene-bridged bis(fluorenyl) ligands with the borohydride precursor Nd(BH4)3(THF)3. The solid state structures of dimeric 1 and monomeric 2 ate complexes were established by X-ray diffraction studies. We showed that these complexes used in combination with (nBu)(nOct)Mg are highly efficient for cyclocopolymerization of ethylene with butadiene leading to a new class of elastomers. Catalyst 1/(nBu)(nOct)Mg provided elastomers with a polyethylene skeleton incorporating unsaturated groups (trans double bond and pendant vinyl units) and 1,2-cyclohexane rings. These rings are formed via an intramolecular cyclization which occurs with a high trans selectivity. The investigation of catalyst 2/(nBu)(nOct)Mg has revealed that the tertio-butyl substitution in positions 2 and 7 of fluorenyl ligands influenced the microstructure...

Mixtures of lidocaine with a long-acting local anesthetic are commonly used for peripheral nerve block. Few data are available regarding the safety, efficacy, or pharmacokinetics of mixtures of local anesthetics. In the current study, we compared the effects of bupivacaine 0.5% or ropivacaine 0.75% alone or in a mixed solution of equal volumes of bupivacaine 0.5% and lidocaine 2% or ropivacaine 0.75% and lidocaine 2% for surgery after femoral-sciatic peripheral nerve block. The primary end point was onset time.In a double-blind, randomized study, 82 adults scheduled for lower limb surgery received a sciatic (20 mL) and femoral (20 mL) peripheral nerve block with 0.5% bupivacaine (200 mg), a mixture of 0.5% bupivacaine 20 mL (100 mg) with 2% lidocaine (400 mg), 0.75% ropivacaine (300 mg) or a mixture of 0.75% ropivacaine 20 mL (150 mg) with 2% lidocaine (400 mg). Each solution contained epinephrine 1:200,000. Times to perform blocks, onset times (end of injection to complete sensory and motor block), duration of sensory and motor block, and morphine consumption via IV patient-controlled analgesia were compared. Venous blood samples of 5 mL were collected for determination of drug concentration at 0, 5, 15, 30, 45, 60, and 90 min after placement of the block.Patient demographics and surgical times were similar for all four groups. Sciatic onset times (sensory and motor block) were reduced by combining lidocaine with the long-acting local anesthetic. The onset of bupivacaine-lidocaine was 16 +/- 9 min versus 28 +/- 12 min for bupivacaine alone. The onset of ropivacaine-lidocaine was 16 +/- 12 min versus 23 +/- 12 for ropivacaine alone. Sensory blocks were complete for all patients within 40 min for those receiving bupivacaine-lidocaine versus 60 min for those receiving bupivacaine alone and 30 min for those receiving ropivacaine-lidocaine versus 40 min for those receiving ropivacaine alone (P0.05). Duration of sensory and motor block was significantly shorter in mixture groups. There was no difference among groups for visual analog scale pain scores and morphine consumption during the 48 h postoperative period, except for bupivacaine alone (median: 9 mg) versus bupivacaine-lidocaine mixture (15 mg), P0.01. There was no difference in the incidence of adverse events among groups. Plasma concentrations of bupivacaine and ropivacaine were higher, and remained elevated longer, in patients who received only the long-acting local anesthetic compared to patients who received the mixture of long-acting local anesthetic with lidocaine (P0.01).Mixtures of long-acting local anesthetics with lidocaine induced faster onset blocks of decreased duration. Whether there is a safety benefit is unclear, as the benefit of a decreased concentration of long-acting local anesthetic may be offset by the presence of a significant plasma concentration of lidocaine.

Resume Apres une forte diminution des transfusions, la tendance depuis le debut des annees 2000 est a la remontee du nombre de transfusions. L’epargne transfusionnelle est limitee par des seuils transfusionnels qui ne doivent pas etre sous-evalues. Nous devons donc etre tres vigilants sur la strategie transfusionnelle perioperatoire qui doit etre encadree par les recommandations des societes savantes. Cette strategie comprend l’amelioration des techniques chirurgicales, l’utilisation optimale de la transfusion autologue perioperatoire et des medicaments et techniques favorisant l’epargne sanguine. Il s’agit donc d’une veritable strategie multimodale qui necessite en permanence l’evaluation des rapports benefices-risques de la reduction transfusionnelle en regard des indications de transfusion des produits sanguins labiles qu’il ne faut pas remettre en cause etant donne la grande securisation de la transfusion homologue.

International audience; Ethylene/butadiene copolymerization can be performed by neodymocene catalysts in the presence of an alkylating/chain transfer agent. A variety of polymerization activities and copolymer microstructures can be obtained depending on the neodymocene ligands. For a set of four catalysts, namely (C5Me5)2NdR, [Me2Si(3-Me3SiC5H3)2]NdR, [Me2Si(C5H4)(C13H8)]NdR and [Me2Si(C13H8)2]NdR, we report a DFT mechanistic study of this copolymerization reaction performed in the presence of dialkylmagnesium. Based on the modeling strategy developed for the ethylene homopolymerization catalyzed by (C5Me5)2NdR in the presence of MgR2, our model is able to account for the following: (i) the formation of Nd/Mg heterobimetallic complexes as intermediates, (ii) the overall differential activity of the catalysts, (iii) the copolymerization reactivity indexes, and (iv) the specific microstructure of the resulting copolymers, including branching and cyclization. The analysis of the reaction mechanisms and the energy profiles thus relates ligand structure, catalyst activity, and polymer microstructure and sets the basis for further catalyst developments.

A new class of well-defined activating supports for olefin polymerization was obtained via the surface organometallic chemistry approach. High activities in slurry polymerization of ethylene along with industrial-grade physical properties of the resulting polyethylene were obtained when these activators were combined with metallocene complexes in the presence of triisobutylaluminium.

Polyolefins account for more than half of worldwide production of thermoplastics. The majority is used as commodity polymers but they may also provide the starting backbones for original architectures. Most polyolefins are obtained by catalytic polymerization and this powerful technique may be used to produce polyolefins incorporating interesting functional groups that can serve as initiating sites for other successively applied polymerization techniques. This review describes the state of the art in strategies employing catalytic olefin polymerization followed by a living or controlled polymerization. The latter methodologies are classified according to the living/controlled polymerization technique used including anionic polymerization, nitroxide-mediated radical polymerization (NMRP), atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT).

Resume Introduction Le bloc tronculaire du nerf femoral a ete propose comme technique analgesique simple et efficace apres fracture du col du femur. Cette modalite d'analgesie administree en continue par catheter femoral (CF) est comparee a deux procedures d'analgesie classique : morphine sous-cutanee (s.c.) (M) et propacetamol intraveineuse (i.v.) (P). Methode Les patients (n = 62) operes sous anesthesie spinale etaient inclus et randomises en trois groupes en postoperatoire : groupe CF (catheter femoral : voie inguinale paravasculaire, injection d'un bolus initial et entretien par injection continue de ropivacaine 0,2 %), groupe P (propacetamol i.v. 2 g/6 heures), groupe M (Morphine s.c. : 0,05 mg/kg toutes les quatre heures). Une analgesie additionnelle etait standardisee : titration morphine intraveineuse puis relais par voie sous-cutanee par quatre heures. La consommation morphinique etait le critere principal de jugement. Les criteres secondaires etaient colliges : en effets adverses (morphine), morbidite, mortalite et score EVA. Resultats Les caracteristiques chirurgicales et anesthesiques etaient similaires pour les trois groupes. Apres titration morphinique, les scores EVA etaient similaires entre les groupes de 0 a 48 heures. La consommation totale de morphine etait plus elevee dans le groupe CF : 26 mg (5–42) versus P : 8 mg (3–12) (p = 0,0001) ou M : 19 mg (8–33) (p Conclusion L'analgesie par catheter femoral continu apres fracture du col du femur ne montre pas de reel benefice pour un cout financier significativement plus eleve.

International audience; Ethylene polymerizations were performed in toluene using the neodymocene complex (C5Me5)2NdCl2Li(OEt2)2 or {(Me2Si(C13H8)2)Nd(μ-BH4)[(μ-BH4)Li(THF)]}2 in combination with n-butyl-n-octylmagnesium used as both alkylating and chain transfer agent. The kinetics were followed for various [Mg]/[Nd] ratios, at different polymerization temperatures, with or without ether as a cosolvent. These systems allowed us to (i) efficiently obtain narrowly distributed and targeted molar masses, (ii) characterize three phases during the course of polymerization, (iii) estimate the propagation activation energy (17 kcal mol–1), (iv) identify the parameters that control chain transfer, and (v) demonstrate enhanced polymerization rates and molar mass distribution control in the presence of ether as cosolvent. This experimental set of data is supported by a computational investigation at the DFT level that rationalizes the chain transfer mechanism and the specific microsolvation effects in the presence of cosolvents at the molecular scale. This joint experimental/computational investigation offers the basis for further catalyst developments in the field of coordinative chain transfer polymerization (CCTP).

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A Lewis acid surfactant combined catalyst (LASC) was tentatively used in a cationic polymerization in miniemulsion of p-methoxystyrene (pMOS). In a first part, the initiating potential of trisdodecyl sulfate ytterbium (Yb(DS)3, 0.25H2O) was evidenced in the solution polymerization of pMOS initiated by the corresponding chlorinated adduct pMOS−HCl. Miniemulsion polymerizations of pMOS performed using the same initiating system gave rise to oligomers, but experimental conditions chosen could not evidence the expected LASC-mediated cationic polymerization process. Further studies showed that LASC is located at the interface and acts only as a surfactant together with SDS. The polymerization occurred due to the hydrolysis of pMOS−HCl. The resulting acidification of the water phase leads to the transformation of SDS into its sulfuric acid form acting as an inisurf according to an interfacial cationic polymerization process. Latex particles of pMOS incorporating narrowly distributed low molar mass chains were o...

We present the design and synthesis of a linear ABC triblock terpolymer for the bottom-up synthesis of anisotropic organic/inorganic hybrid materials: polyethylene-block-poly(2-(4-(tert-butoxycarbonyl)amino)butyl-2-oxazoline)-block-poly(2-iso-propyl-2-oxazoline) (PE-b-PBocAmOx-b-PiPrOx). The synthesis was realized via the covalent linkage of azide-functionalized polyethylene and alkyne functionalized poly(2-alkyl-2-oxazoline) (POx)-based diblock copolymers exploiting copper-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry. After purification of the resulting triblock terpolymer, the middle block was deprotected, resulting in a primary amine in the side chain. In the next step, solution self-assembly into core-shell-corona micelles in aqueous solution was investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Subsequent directional crystallization of the corona-forming block, poly(2-iso-propyl-2-oxazoline), led to the formation of anisotropic superstructures as demonstrated by electron microscopy (SEM and TEM). We present hypotheses concerning the aggregation mechanism as well as first promising results regarding the selective loading of individual domains within such anisotropic nanostructures with metal nanoparticles (Au, Fe3O4).

Well-defined, crystalline, low molar mass polyethylene PEx (where x is the molar mass 1300 and 2200 g mol–1) bearing thymine (Thy) or 2,6-diaminotriazine (DAT) end groups have been synthesized from amino-terminated PE. Either double-layer or monolayer solid-state morphologies were attained depending on the nature of the end-group(s). PE1300-NH2, PE1300-DAT, and the equimolar blend PE1300-Thy/DAT-PE1300 all organized into double-layer structures composed of extended PE chains sandwiched between H-bonding chain-ends. The double-layered morphology arose from the microphase separation of the polar end-groups and the nonpolar PE chains and was frozen by the crystallization of the PE domains. The regularity of the PE lamellar stacking was higher for the stronger and more directional associated pair Thy/DAT compared with samples of either PE-NH2 or PE-DAT. For PE1300-Thy, the mesoscopic organization was driven by the crystallization of Thy domains prior to crystallization of the PE chains, forcing the small prop...

In slurry and gas phase catalytic ethylene polymerization processes, aluminum alkyl (AlR3) compounds are usually present inside the reactor and their role either as co-catalyst or scavenger is of considerable importance. Silica supported metallocene/methyl aluminoxane (MAO) catalysts show specific interactions with AlR3 compounds. Therefore, this study shows an attempt to analyze and compare the effect of concentration as well as type of commonly used AlR3 on slurry phase ethylene homopolymerization kinetics of silica supported (n-BuCp)2ZrCl2/MAO catalyst. The obtained results indicate that the lower the concentration of smaller AlR3 compounds, the higher the instantaneous catalytic activity. Concerning the polymer particle size distributions, a rise in fines generation has been observed with increasing AlR3 content inside the reactor. Finally, it has been shown that the addition of 2,6-di-tert-butyl-4-methylphenol (a substituted phenol) into the reactor containing AlR3 reduces the influence of AlR3 compounds on the reaction kinetics of silica supported metallocene/MAO catalysts. Polyethylene properties remain similar in all the studied scenarios. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45670.

We report a case of delayed rocuronium-induced deep block antagonization with sugammadex, thus requiring a total of three injections and a cumulative dose of 12 mg/kg over a 30 min period. The patient was an emergency case with full stomach that had required a rapid sequence induction. Because of hyperkaliemia due to an acute renal failure, rocuronium was preferred to succinylcholine. Use of sugammadex in the acute renal failure context is discussed.

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The synthesis of lanthanide(III) alkoxides has been described as a series of reactions for which the control of product purity is difficult. The possibility of using amide complexes, in the presence of alcohol, to produce alkoxides was investigated in homogeneous and heterogeneous media. The polymerization of e-caprolactone with alkoxides formed in situ was performed with and without excess alcohol. The latter system was efficient since the polymers were obtained in a short time period, with a well-controlled molecular weight and low polydispersity. The alcohol functionalized all the polymer chains.

Nitrogen-based organolanthanide complexes: (Siam)3Ln (Ln=Yb, 1a, Sm, 1b), (C5H4CMe2)2Sm(Siam), 2, (COT)SmN(SiMe3)2, 4 (Siam=PhC(NSiMe3)2, COT=C8H8), are very efficient towards polymerisation of e-caprolactone. Mechanistic studies on the basis of NMR experiments show that the complexes 1a, 1b and 2 behave as real catalysts, while 4 is the precursor of a heterogeneous initiator. The hapticity of the nitrogen ligand may be related to the formation of cyclic oligomers. © 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS organolanthanide / e-caprolactone / polymerisation

The aim of this study was to determine whether changing heat and moisture exchangers (HMEs) every 96 hrs rather than 24 hrs would affect their efficacy to preserve the heat and moisture of inspiratory gases. The impact of a prolonged use of the HME on its microbial colonization was also assessed.Prospective cohort observational study.Intensive care unit of a university hospital.Thirteen consecutive patients with no previous history of respiratory disease requiring controlled mechanical ventilation with an HME for4 days were evaluated.The same HME was used for 96 hrs in each patient.In each patient, during the inspiration phase, the following measurements were performed: peak and mean airway pressures, mean values of temperature, and relative and absolute humidity of inspired gases. In each patient, measurements were performed after 1 hr of HME use and then daily up to the fourth day. On days 1 and 4, microbiological samples were obtained from the patients' bronchial secretions and the ventilator side of the HME. After 96 hrs of ventilation with the same HME, tracheal tube occlusion was never observed. Using the same HME for 96 hrs rather than 24 hrs did not affect its technical performances: temperature at 24 hrs: 32.2 +/- 1.5 degrees C (90.0 +/- 34.7 degrees F), at 96 hrs: 32.1 +/- 1.6 degrees C (89.8 +/- 34.9 degrees F); relative humidity at 24 hrs: 97.9 +/- 2%, at 96 hrs: 98.1 +/- 1.7%; absolute humidity at 24 hrs: 33.1 +/- 2.4 mg H2O/L, at 96 hrs: 33.0 +/- 2.5 mg H2O/L. This analysis was based on a total of 312 measurements performed on the 13 patients. Peak and mean airway pressures did not change during the 96-hr study period, with identical tidal and minute volumes in the study patients. On day 1, ten patients had a positive culture of their tracheal secretions at a colony count ofor = 10(3) colony forming units/mL. After 96 hrs of use with the same HME, only seven patients had a positive culture of their tracheal secretions. Cultures from the ventilator sides of the HMEs were all sterile (13/13) after 96 hrs of use.In patients free from previous chronic respiratory disorder and ventilated for neurologic reasons, changing the HME after 96 hrs rather than 24 hrs did not affect its technical performance in terms of heat and water preservation of ventilatory gases. There is also some indirect evidence of very little, if any, changes in the HME resistance. No bacterial colonization of the ventilator sides of the HMEs was observed after 96 hrs of use. However, other large clinical trials should be undertaken to confirm the safety of extending the time between HME changes.

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International audience; The cationic uranium amide compound [U($Cp^{∗}$$)_{2}$(N$Me_{2}$)(THF)][B$Ph_{4}$] 1 (($Cp^{∗}$ = $\eta$-$C_{5}$$Me_{5}$, THF = tetrahydrofuran) was transformed into the heterocyclic metallacycle |(($Cp^{∗}$$)_{2}$U(O(C$H_{2}$$)_{4}$N$Me_{2}$((C$H_{2}$$)_{4}$O)B$Ph_{4}$| ·0.5THF 2 in the presence of a catalytic amount of the free amine N$R_2$H (R = Me, Et). Treatment of 1 with $^{t}Bu$NC afforded the isocyanide adduct [U($Cp^{∗}$$)_{2}$(N$Me_{2}$)(CN$^{t}Bu$$)_{2}$][B$Ph_{4}$] whereas reactions with MeCN, C$O_2$ and CO gave the insertion compounds [U($Cp^{∗}$$)_{2}$(NC{Me}{N$Me_{2}$})(THF)][B$Ph_{4}$] 5, [U(($Cp^{∗}$$)_{2}$ ($O_{2}$CN$Me_{2}$)(THF)][B$Ph_{4}$] 6 and [U(($Cp^{∗}$$)_{2}$($\eta_{2}$-CON$Me_{2}$)(THF)][B$Ph_{4}$] 7. The crystal structure of a THF solvate of 4 has been determined.

To compare the patterns of evolution of two proinflammatory cytokines (tumor necrosis factor [TNF]-alpha and interleukin-6 [IL-6]) in two major clinical entities associated with systemic inflammatory response: septic shock and multiple trauma (with and without hemorrhagic shock).Prospective study of two cohorts of patients.Critical care unit and Emergency Center of a university hospital.Twenty-five nontrauma patients with septic shock and 60 multiple trauma patients (of whom eight patients were resuscitated from hemorrhagic shock).Serial blood samples were collected in each patient for determination of serum cytokine concentrations. Samples were obtained over 7 days in septic shock patients and 11 days in trauma patients. Standard resuscitation techniques were used in each patient. Clinical and laboratory data were prospectively collected.High concentrations of circulating TNF-alpha and IL-6 were found in patients with septic shock. High IL-6 concentrations, but normal TNF-alpha concentrations were detected in trauma patients. At study entry, TNF-alpha concentrations were higher in nonsurvivor septic shock than in nonsurvivor trauma patients (42 +/- 7 vs 13 +/- 2 pg/mL; p.001). During the whole study period, nonsurvivor septic shock patients maintained higher TNF-alpha concentrations than nonsurvivor trauma patients (p.001). In survivors in both groups, normal values for TNF-alpha were detected during the whole study period. At study entry, IL-6 concentrations were significantly higher in nonsurvivor septic shock patients than in nonsurvivor trauma patients (15,627 +/- 4336 vs. 317 +/- 124 pg/mL; p.0001). During the whole study period, much higher concentrations of IL-6 were detected in septic shock patients than in trauma patients (p.0001). In survivors, at study entry, IL-6 concentrations were much higher in septic shock patients than in trauma patients (3947 +/- 1410 vs. 247 +/- 41 pg/mL; p.001). Higher IL-6 concentrations were maintained throughout the study period in septic shock patients than in trauma patients (p.001). In septic shock patients, changes in both TNF-alpha and IL-6 were correlated with outcome, higher values being found in patients likely to die. Neither TNF-alpha nor IL-6 values were of any significant value in predicting outcome of trauma patients. When septic shock patients were compared with traumatized patients resuscitated from hemorrhagic shock, the former had much higher concentrations of both TNF-alpha and IL-6 throughout the study period (p.01 to p.00001). Increased IL-6 values were an indicator of the development of a nosocomial infection in trauma patients. In five trauma patients who developed a nosocomial pneumonia during the study period, the IL-6 concentration was 433 +/- 385 pg/mL before the onset of pneumonia, then peaked at 3970 +/- 1478 pg/mL on day 7, and returned to baseline (219 +/- 58 pg/mL) on day 11.In septic shock patients, high amounts of circulating TNF-alpha and IL-6 are found and then correlate with fatal outcome. In trauma patients (even those patients resuscitated from hemorrhagic shock), much less increased concentrations of IL-6 are detected while normal TNF-alpha circulating concentrations are measured. In these patients, cytokine concentrations do not correlate with outcome. This finding suggests a much higher degree of activation of the immunoinflammatory cascade in septic shock than in multiple trauma patients. Increased IL-6 values are an indicator of the development of a nosocomial infection in trauma patients.

Blood transfusion has increased significantly during the last decade and blood wastage reduction is a medical and economic challenge in hospital practice and for institutional quality, particularly in the ICU and operating theatre.To evaluate the impact of multiple strategies in one hospital to reduce red blood cell wastage.Multicentre, prospective, comparative, observational study.Over 10 years, the study was conducted over two time periods. During the first period (2000 to 2003), information was given to medical professionals about blood wastage, and audits (reasons for wastage) were performed, in a large teaching institution (more than 4% wastage in 1999). The second period (2004 to 2010) was designed to analyse the impact of seven strategies intended to minimise blood wastage. Blood wastage reduction in the local centre was compared with regional (64 institutions) and national centres (1470 institutions). Reduction was compared using the Mann-Kendall non-parametric trend test.Local centre (22,572 transfused patients, Nîmes, France), regional centre (South France, 64 institutions, 208,525 transfused patients) and national centres (France, 1470 institutions).Medical and surgical procedures.The primary end-point was to describe the percentage of blood wastage for two periods in a local centre. The secondary objective was to compare the percentage of blood wastage in the local centre with wastage at regional and national centres.Over the 10 year study period the percentage of blood wastage in the local centre decreased, with a significant reduction in the second period, from more than 4% (1999) to less than 1% (2010; P0.05). Blood wastage at regional and national centres was never less than 1%. Inadequate containers for transport, absence of a temperature analyser in the ICU and inadequate intraoperative blood strategies (excessive orders of blood) were the main causes of wastage. Correction of these points affected the outcome favourably in the second period, but transfusion information was poor in the first period.Seven simple strategies (including transport containers with an effective temperature analyser and audits) decreased blood wastage, especially in the ICU and operating theatre.

Summary 2 laboratory-scale reactor systems suitable for gas phase, and for solution or slurry polymerisations are discussed. The underlying concept behind the design and use of these reactors is that they can be used to understand the impact of conditions specific to different time scales and/or length scales inherent to large reactors that are difficult to recreate at the laboratory scale. For instance the fixed bed gas phase reactor is used to study the influence of different relative gas/solid velocities on the evolution of the molecular weight distribution of the nascent polymer. It is shown that in certain conditions, changing the heat transfer characteristics does not change the observed yield, but will impact the polymer properties. In the case of the solution reactor, the concept is to design and use a reactor to study the activation of unsupported metallocenes. Here it is shown that different metallocenes have very different activation profiles to a point where a stopped flow reactor might not be the ideal tool for their study.

International audience; Polyethylenes and azide-terminated polyethylenes can be converted to macroradicals and nitrenes, respectively followed by addition reactions onto the unsaturated system of graphite oxide sheets. For the first time, the addition of these macroradicals to graphite oxide sheets was compared by performing grafting reactions at 190 degrees C in 1,2,4-trichlorobenzene as a solvent and at 100 degrees C followed by a solvothermal reduction at 150 degrees C in a solvent mixture of 1,4-dioxane and 1,2-dichlorobenzene. Dispersion of PE coated graphite oxide in a DMF-heptane mixture was utilised to follow the introduction of polyethylene onto the GO sheet surface while the thermogravimetric analysis indicated the extent of this grafting. The grafting ratio was found to be in the 1.5 wt% range and despite this low grafting content, the amount of grafted PE was high enough to dramatically improve the affinity of GO with the heptane phase in the DMF-heptane (50/50 v/v) mixture. Polyethylene functionalised GO was imaged by scanning electron microscopy showing a significant difference in morphology between the two grafting paths. It was found that a higher level of grafting was obtained using a radical grafting reaction in the presence of benzoyl peroxide rather than the thermal cleavage of PE-N-3 onto GO while a similar grafting content was obtained with the thermal cleavage of PE-N-3 onto GO grafted trimethoxy(7-octen-1-yl)silane.

Despite the fact that the very early stages (several tens of seconds) of catalysed olefin polymerisation processes appear negligibly short with respect to the residence time of most industrial reactors, they are critical in terms of catalyst activation, obtaining good particle morphology, and avoiding irreparable problems caused by particle overheating. The different types of reactors that have been used over the course of the past few years are discussed in this feature article. It is shown that despite the difficulties encountered in finding the perfect experimental tool for this purpose, different configurations of stopped flow reactors can be used successfully to explore different aspects of what happens to the catalyst (supported and molecular) during these critical moments of polymerisation. © 2012 Canadian Society for Chemical Engineering

International audience; Enhanced spin capturing polymerization (ESCP)-a recent and versatile technique in the field of controlled radical polymerization-achieves control over molecular weights and the synthesis of complex copolymer structures for a wide range of monomers. In the present work, the use of ESCP was extended to the radical polymerization of ethylene under mild conditions (low temperature and medium ethylene pressure) using a nitrone as spin trapping agent. It was demonstrated that the evolution of polyethylene (PE) molecular weight can be accurately described by classical ESCP kinetic equations. A PE bearing a midchain alkoxyamine function was thus obtained with high selectivity (90%). A more complex structure was produced from the radical polymerization of ethylene in the presence of a midchain alkoxyamine-functionalized polystyrene (PS) synthesized by ESCP in the form of ABA triblock copolymer (where A is polystyrene and B polyethylene).

International audience; Thiol end functionalized polyethylenes (PE-SH, Mn around 1000 g mol−1, Đ \textless 1.3) were used as nucleophiles in thia-Michael additions with different acrylic molecules. It was found that under commonly used practical conditions the addition to methacrylates was very difficult, whereas addition to acrylates was very efficient. First, block copolymers based on PE and poly(methyl methacrylate) (PMMA) were targeted by reaction of PE-SH with PMMA obtained by catalytic chain transfer polymerization (CCTP). The reaction however failed and detailed model experiments using butanethiol and a dimer of MMA showed that the solubilization temperature of PE-SH was an impediment to the success of the reaction. The lack of reactivity towards PMMA obtained by CCTP and methacrylate functions was advantageously used to react molecules containing both an acrylate and a methacrylate group in the presence of tributyl phosphine (PBu3) to produce methacrylate-type PE macromonomers. The presence of a hydroxyl function on 3-(acryloyloxy)-2-hydroxypropyl methacrylate induced side trans-esterification reactions catalyzed by PBu3. This was overcome by using the hydroxyl free 2-(acryloyloxy) ethyl methacrylate. With the latter, the desired PE macromonomer exhibited a functionality as high as 85%. Alternatively, 2-isocyanatoethyl methacrylate could also be reacted with PE-SH to produce a highly functionalized methacrylate type PE macromonomer (functionality 89%). Eventually, the efficiency of the thia-Michael addition of PE-SH onto poly(ethylene glycol) acrylate (PEG-acrylate) was used to synthesize the PE-b-PEG block copolymer.

International audience; A poly(glycidyl methacrylate) (PGMA) synthesized by RAFT polymerization was spin-coated onto a silicon substrate to yield, after annealing and rinsing unreacted chains, covalently attached epoxy-containing PGMA pseudo-brushes. A tailor-made ω-amino-poly(ethylene) (Mn = 1040 g mol−1, PDI = 1.3) was then grafted in melt at 130 °C for 24 h by reaction between amine chain-ends and surface-tethered epoxy groups. After discarding unreacted poly(ethylene) chains by sonication and Soxhlet rinsing, the resulting poly(ethylene) brushes were characterized by scanning probe microscopy, water contact angle and neutron reflectivity measurements. The grafting of poly(ethylene) brushes to silicon substrates has thus been demonstrated for the first time and resulted in nanostructured grafted layers with homogeneous surface coverage.

Neutral NiII complexes, classically used for catalytic ethylene polymerization, can play an additional role as radical initiators of the homo- and copolymerizations of (meth)acrylates and styrene. Benefiting from this duality, the copolymerization of ethylene and various (meth)acrylates or styrene was successfully performed. Multiblock copolymers containing sequences of both ethylene and (meth)acrylates were prepared for the first time from an original dual radical/catalytic mechanism.

A route to fully miscible polyethylene (PE) nanocomposites has been established based on polymer-brush-coated nanoparticles. These nanoparticles can be mixed with PE at any ratio, with homogeneous dispersion, and without aggregation. This allowed a first systematic study of the thermomechanical properties of PE nanocomposites without interference from aggregation effects. We observe that the storage modulus in the semicrystalline state and the softening temperature increase significantly with increasing nanoparticle content, whereas the melt viscosity is unaltered by the presence of nanoparticles. We show that the complete miscibility with the semicrystalline polymer matrix and the improvement of thermomechanical properties in the solid state is caused by the PE-coated nanoparticles being nucleating agents for the crystallization of PE. This provides a general route to fully miscibility nanocomposites with semicrystalline polymers.

In the current contribution it is demonstrated - for the first time - that poly(ethylene) (M(n) = 1,400 as well as 2,800 g · mol(-1) , PDI = 1.2) can be readily equipped with highly reactive cyclopentadienyl (Cp) end groups. The Cp terminal poly(ethylene) can subsequently be reacted in an efficient hetero Diels-Alder (HDA) reaction with macromolecules (poly(isobornyl acrylate) (M(n) = 4,600 g · mol(-1) , PDI = 1.10) and poly(styrene) (M(n) = 6,300 g · mol(-1) , PDI = 1.13) featuring strongly electron withdrawing thiocarbonyl thio end groups, prepared via reversible addition fragmentation chain transfer (RAFT) polymerization employing benzylpyridin-2-yldithioformate (BPDF) as transfer agent. The resulting block copolymers have been analyzed via high-temperature size exclusion chromatography (SEC) as well as nuclear magnetic resonance (NMR) spectroscopy. The current system allows for the removal of the excess of the non-poly(ethylene) containing segment via filtration of the poly(ethylene)-containing block copolymer. However, the reaction temperatures need to be judiciously selected. Characterization of the generated block copolymers at elevated temperatures can lead - depending on the block copolymer type - to the occurrence of retro Diels-Alder processes. The present study thus demonstrates that RAFT-HDA ligation can be effectively employed for the generation of block copolymers containing poly(ethylene) segments.

International audience; Synthesis of highly end-functionalized polyethylene chains was accomplished using both coordination chemistry and radical mediated thiol?ene chemistry. A vinyl end-terminated polyethylene (Mn =1440 g·mol?1, PDI = 1.8) with a functionalization rate of 100% was synthesized using a P,O-chelated catalyst [Ni\Ph2PC(COOEt)═C(C6H5)O\Ph(PPh3)]. Thiol?ene reactions were subsequently undertaken between vinyl-terminated polyethylene and the thiol-containing molecules thioglycolic acid, 2-mercaptoethanol, 1-thioglycerol, chloropropanethiol, and methyl thioglycolate. A range of end-functionalized polyethylenes was thus prepared using simple reaction conditions and exhibiting degrees of functionalization higher than 93%.

International audience

International audience; An alpha-[Cu(II)-porphyrin]-polyethylene was synthesized for the first time using copper catalyzed 1,3-dipolar azide-alkyne Huisgen cycloaddition yielding highly colored moiety-substituted polyethylene.

International audience; Nickel complexes [(X,O)NiR(PPh(3))] (X = N or P), designed for the polymerization of ethylene, were found to be efficient for the homo- and copolymerization of butylacrylate (BuA), methylmethacrylate (MMA), and styrene. Their role as a radical initiator was demonstrated from the calculation of the copolymerization reactivity ratios. It was shown that the efficiency of the radical initiation is improved by the addition of PPh3 to the nickel complexes as well as by increasing the temperature. The dual role of a nickel complex as radical initiator and catalyst was exploited to succeed in the copolymerization of ethylene with BuA and MMA. Multiblock copolymers containing sequences of both ethylene and polar monomers were thus prepared for the first time by a dual radical/catalytic mechanism.

International audience; Copolymers of ethylene with methyl methacrylate (EMMA) and butyl acrylate (EBA), which are of different average chemical composition and block lengths according to NMR analysis, were analyzed by size exclusion chromatography (SEC), differential scanning calorimetry (DSC), Crystallization Analysis Fractionation (CRYSTAF), and high performance liquid chromatography at high temperature (HT-HPLC). With CRYSTAF and DSC crystallizing fractions were detected only in some samples. HT-HPLC fractionated all the samples irrespective of their crystallinity. Homopolymers, PMMA and PE were also found in the copolymer samples of EMMA. EMMA and EBA were separated in HPLC according to the content of polar comonomer. A linear correlation between the MMA content and elution volume could not be established due to the presence of homopolymers as admixtures. In such a case the average chemical composition obtained by NMR does not correspond to the real chemical composition of the copolymers. Unlike EMMA the EBA samples eluted in single peaks, which was used for evaluation of their chemical composition distribution. The comparison of results obtained by fractionation via CRYSTAF and HT-HPLC clearly demonstrates the advantages of the chromatographic approach to study the chemical heterogeneity of olefin based copolymers.

The reaction of silylene-bridged bis(fluorenyl)dipotassium salts with neodymium tris(borohydride) afforded new neutral ansa-bis(fluorenyl)silane neodymium borohydrides: (Flu2SiR2)Nd(BH4)(THF) [R2 = Me2, Et2, (CH2)3, Me(Ph), Flu = C13H8] that were better characterised and more soluble than the previously described anionic [(Flu2SiMe2)Nd(BH4)2]−. The X-ray structures of three of these complexes were determined, and their solid-state geometrical parameters are very similar, despite the ring strain introduced by the silacyclobutane bridge in [Flu2Si(CH2)3]Nd(BH4)(THF). The main geometrical features were satisfactorily reproduced by DFT calculations. The catalytic activity of the title complexes in ethylene–butadiene copolymerisation reactions was assessed and compared to that of the reported activity of [(Flu2SiMe2)Nd(BH4)2]− under similar conditions. From these results it can be concluded that the cyclo-copolymerisation of ethylene with butadiene is characteristic of a catalyst featuring silylene-bridged bis(fluorenyl) ligands around neodymium, and appears to be independent of the substituents at the silicon atom.

International audience; Free radical polymerization of ethylene in an intermediate pressure and temperature range (P(ethylene) < 250 bar and 50 degrees C < T < 90 degrees C) in the presence of an organic solvent has been studied. Under selected conditions ( P, T) and according to the amount of organic solvent added, either a supercritical monophasic or a biphasic medium is obtained. In the case of a biphasic medium, polymerization occurred in the liquid phase in which radical initiator and ethylenes are dissolved. The transition between a monophasic to a biphasic medium has been predicted using thermodynamic calculations and has been related to experimental observations such as the dependence of polymerization activity versus solvent volume.

International audience; Ethylene polymerization is performed industrially either by radical polymerization under severe conditions (1000-4000 bar, 200-300°C) or by catalytic mechanism at lower temperatures (usually less than 100°C) and pressures (below 50 bar). Standard radical polymerization conditions are too severe to permit a fine control of the macromolecular architecture. Under milder conditions radical ethylene polymerization is assumed to be ineffective, which has been confirmed using toluene as solvent. The efficiency of free radical polymerization under mild conditions (up to 250 bar of ethylene and a polymerization temperature between 50°C to 90°C) has been investigated in THF which is a more polar solvent than toluene. In this solvent, polyethylene has been obtained with relatively good yields highlighting an unexpected high solvent effect in the free radical ethylene polymerization. This solvent effect has been rationalized using theoretical considerations