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EEGs are known to provide biomarkers for consciousness. Although EEG correlates of loss of consciousness (LOC) are often ascribed to changes in neural synchrony, mounting evidence suggests that some changes result from asynchronous neural activity. By combining EEG recordings of humans undergoing propofol administration with biophysical modelling, we present here a principled decomposition of EEG changes during LOC into synchronous and asynchronous sources. Our results reveal that IPSP decay rate and mean spike rate shape aperiodic EEG features, and that propofol’s effects on these parameters largely explain the changes in EEG spectra following propofol infusion. We further show that traditional spectral EEG analysis likely conflates these effects with changes in rhythmic activity, thereby masking the true dynamics of neural synchrony. We conclude that the well-documented propofol-induced alpha rhythm in fact appears before LOC, and that the moment of LOC is uniquely correlated with the sudden appearance of a delta rhythm.

The conversion of neuraxial anesthesia (NA) to general anesthesia (GA) during a cesarean section (CS) may be associated with a higher risk of neonatal morbidity by adding the undesirable effects of both these anesthesia techniques. We aimed to compare the neonatal morbidity of non-elective CS performed after conversion from NA to GA (secondary GA) vs. that after GA from the outset (primary GA).We performed a monocentric retrospective study at the Angers University Hospital (France). All non-elective CSs performed under GA between January 2015 and December 2019 were included. The CSs were classified using a three-color coding system (green for non-urgent delivery, orange for urgent CS, and red for very urgent CS). The primary neonatal outcome was a composite of umbilical artery pH7.10 or 5-min Apgar score7. The crude and adjusted odds ratios (OR) for the risk of neonatal morbidity associated with secondary GA were estimated.We included 247 patients, of whom 101 (41.3%) had a secondary GA and 146 (58.7%) had primary GA. In the secondary GA group, 86.1% (87/101) had epidural anesthesia and 13.9% (14/101) had spinal anesthesia. Multivariate analysis showed no difference in neonatal morbidity between the two groups (adjusted odds ratio 1.18, 95% CI 0.56 to 2.51).Our study found insufficient evidence to identify a difference in neonatal outcomes between secondary compared with primary GA for CS, regardless of the level of emergency. However, our study is underpowered and additional studies are needed to confirm these data.

International audience

International audience

The damping properties of unidirectional, 0/90 and twill 2/2 flax fibre (FF) reinforced epoxy composites containing 40 vol% of fibres have been measured by vibration beam testing (VBT). The influence of the impregnation quality, the fibre/matrix adhesion, the quality of the fibres, the twist of the FF yarns and the crimp in the FF fabrics on these properties was quantified. Carbon and glass fibre reinforced epoxy composites were considered as comparison. Unidirectional FF instead of glass fibres led to a damping increase of 133%. Under the VBT conditions, the inter and intra-yarn frictions mechanisms were dominant leading to energy dissipation. The damping properties increased with the twist and crimp amount, leading to a damping increase of 79% when a twill 2/2 fabric was considered instead of a [0/90] laminate. Fibre/matrix friction improved the damping properties by 23% with a limited fibre/matrix adhesion. Finally damping maps for several material systems were established. (C) 2014 Elsevier Ltd. All rights reserved.

The mechanical and damping properties of unidirectional (UD) and twill 2/2 flax fibre (FF) reinforced thermoset (epoxy) and thermoplastic (polypropylene (PP) and polylactic acid (PLA)) composites containing 40 vol% of fibres have been compared with those of carbon (CF) and glass (GF) fibre reinforced epoxy composites. Thanks to the relatively low density of the FF, the specific mechanical properties of the LID FF based composites were comparable with those of the GF epoxy composites. The composites reinforced with FF also showed improved damping as reflected by dynamic mechanical analysis with respect to composites reinforced with synthetic CF and GF. For example, the addition of UD FF to epoxy led to an approximately 100% increase in loss factor with respect to both the matrix and GF reinforced epoxy. FF/PP showed the highest damping at 25 degrees C and 1 Hz of all the composites investigated (tan delta = 0.033). However the best compromise between stiffness and damping was obtained with FF reinforced semicrystalline PLA. (C) 2014 Elsevier Ltd. All rights reserved.

Resume L’accouchement inopine hors maternite represente, en France, environ 0,5 % de la totalite des accouchements. La parturiente est surveillee de facon continue par un moniteur multiparametrique. La surveillance du rythme cardiaque du fœtus est realisee a l’aide d’un Doppler fœtal. L’analgesie n’est realisee que par l’inhalation au masque a haute concentration d’un melange equimoleculaire d’oxygene et de protoxyde d’azote. Dans certaines situations, en raison d’un terme premature, d’une grossesse gemellaire ou d’une pathologie maternelle ou parfois d’anomalies du rythme cardiaque fœtal, l’assistance d’un SMUR pediatrique peut etre necessaire. La conduite des efforts expulsifs ne doit debuter que lorsque l’on voit apparaitre la presentation a la vulve et seulement si la dilatation est complete et la poche des eaux rompue. L’expulsion ne doit pas durer plus de 30 minutes. Il ne faut pas pratiquer d’episiotomie de facon systematique. Il est recommande de pratiquer une delivrance dirigee. En cas de liquide amniotique clair, et si le nouveau-ne a terme respire, crie, et a un bon tonus, des soins de routine sont realises : rechauffement, essuyage et sechage doux. Trois criteres, evalues toutes les 30 secondes, guident ensuite la prise en charge : la frequence cardiaque, la qualite de la respiration et le tonus musculaire. La redaction d’un certificat de naissance est une obligation legale et incombe au medecin qui a pratique l’accouchement.

L’accouchement inopine hors d’une maternite represente, en France, environ 0,5 % de la totalite des accouchements. La parturiente est installee en decubitus dorsal en travers du lit, fesses au bord du lit, bassin sureleve par les oreillers et les pieds reposant chacun sur une chaise. Elle est surveillee de facon continue par un moniteur multiparametrique. La surveillance du rythme cardiaque du foetus est realisee a l’aide d’un Doppler foetal. L’analgesie n’est realisee que par l’inhalation au masque a haute concentration d’un melange equimoleculaire d’oxygene et de protoxyde d’azote. Dans certaines situations, en raison d’un terme premature, d’une grossesse gemellaire ou d’une pathologie maternelle ou parfois d’anomalies du rythme cardiaque foetal, l’assistance d’un service medical d’urgence et de reanimation (SMUR) pediatrique peut etre necessaire. La conduite des efforts expulsifs ne doit debuter que lorsque l’on voit apparaitre la presentation a la vulve et seulement si la dilatation est complete et la poche des eaux rompue. L’expulsion ne doit pas durer plus de 30 minutes. Il ne faut pas pratiquer une episiotomie de facon systematique. Il est recommande de pratiquer une delivrance dirigee. En cas de liquide amniotique clair, et si le nouveau-ne a terme respire, crie et a un bon tonus, des soins de routine sont realises: rechauffement, essuyage et sechage doux. Trois criteres, evalues toutes les 30 secondes, guident ensuite la prise en charge: la frequence cardiaque, la qualite de la respiration et le tonus musculaire. La redaction d’un certificat de naissance est une obligation legale et incombe au medecin qui a pratique l’accouchement.

Resume Introduction Le laryngoscope Airtraq ® (Vygon, Ecouen, France) permet une vision continue de l’intubation sans alignement des axes oral, pharynge et larynge. Son apprentissage decrit dans la litterature est extremement rapide et il semble bien adapte aux intubations difficiles. Le but de notre travail etait d’evaluer l’interet de l’Airtraq ® utilise par des praticiens inexperimentes dans l’intubation difficile prevue chez l’adulte. Methodes Les patients presentant au moins un des quatre criteres predictifs principaux d’intubation difficile (antecedent d’intubation difficile, distance thyromentale [DTM] inferieure a 60 mm, ouverture de bouche [OB] inferieure a 35 mm, classe de Mallampati 3 ou 4) ont ete inclus dans l’etude. Les praticiens inexperimentes beneficiaient auparavant d’une breve formation orale sur l’utilisation de l’Airtraq ® . Ils etaient encadres par un expert pour l’intubation avec l’Airtraq ® . Pour chaque patient inclus, on notait : le grade de Cormack et Lehane, les temps moyens pour visualiser la glotte et intuber, le succes ou non de la manœuvre d’intubation, les episodes de desaturation arterielle en oxygene, les manipulations et difficultes signalees par les operateurs. Resultats Vingt patients ont ete inclus. Parmi eux, 13 presentaient un antecedent d’intubation difficile, huit une DTM inferieur a 60 mm, neuf une OB inferieura 35 mm et 12 patients etaient classes Mallampati 4. Quatre patients n’ont pas ete intubes avec le laryngoscope Airtraq ® . Pour les autres, les temps moyens d’exposition glottique et d’intubation etaient de 28 et 47 s avec un taux de succes de 80 % (16/20). Discussion Dans la majorite des cas, l’introduction de l’Airtraq ® et la visualisation glottique ont ete simples et rapides, sans desaturation arterielle en oxygene. Cependant, les quatre echecs d’intubation tracheale avec l’Airtraq ® et la prolongation du delai d’intubation observee chez certains patients suggerent que la courbe d’apprentissage du laryngoscope Airtraq ® est certainement plus importante chez les patients presentant des criteres d’intubation difficile.

The swelling and compressive mechanical behavior as well as the morphology and biocompatibility of composite hydrogels based on Tween® 20 trimethacrylate (T3), N-vinyl-2-pyrrolidone (NVP) and nanofibrillated cellulose (NFC) were assessed in the present study. The chemical structure of T3 was verified by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance, and the degree of substitution was found to be around 3. Swelling ratios of neat hydrogels composed of different concentrations of T3 and NVP were found to range from 1.5 to 5.7 with decreasing concentration of T3. Various concentrations of cellulose nanofibrils (0.2-1.6wt.%) were then used to produce composite hydrogels that showed lower swelling ratios than neat ones for a given T3 concentration. Neat and composite hydrogels exhibited a typical nonlinear response under compression. All composite hydrogels showed an increase in elastic modulus compared to neat hydrogel of about 3- to 8-fold, reaching 18kPa at 0% strain and 62kPa at 20% strain for the hydrogel with the highest NFC content. All hydrogels presented a porous and homogeneous structure, with interconnected pore cells of around 100nm in diameter. The hydrogels are biocompatible. The results of this study demonstrate that composite hydrogels reinforced with NFC may be viable as nucleus pulposus implants due to their adequate swelling ratio, which may restore the annulus fibrosus loading, and their increased mechanical properties, which could possibly restore the height of the intervertebral discs.

Ag–28 wt.% Cu open-cell foam is produced by the replication process using MgSO4 as the space holder. Microcellular Ag–28 wt.% Cu of relative density between 36% and 50% and pore size of 300 μm shows good strength and high conductivity, an interesting combination for heat exchanger applications.

Resume A l'aide du modele multidimensionnel de l' « Ouverture emotionnelle » nous explorons les hypotheses suivantes : les patients souffrant d'un Trouble de la dependance ou d'un Trouble de la personnalite presentent une diminution a) de la « representation cognitive et conceptuelle » de leurs etats affectifs ; b) de leur « regulation emotionnelle » et c) de la « communication et expression » de leurs emotions, mais une augmentation d) de la « perception des indicateurs corporels internes » ; e) des interventions psychologiques appropriees ameliorent ces patterns problematiques. Les resultats avec le questionnaire factoriel DOE (« Dimensions de l'Ouverture Emotionnelle ») – dans deux etudes comparant des patients ( n = 71) avec des sujets non cliniques ( n = 101) – confirment les deficits marques selon les hypotheses, en particulier chez les patients avec un double diagnostic qui presentent des deficits encore plus importants en « representation cognitive » et en « regulation des emotions ». En revanche, des comparaisons pre- post-traitement montrent une amelioration du profil DOE. Des implications du dysfonctionnement emotionnel pour la psychotherapie sont discutees.

The title phase and its homogeneity range ( 0.12 ⩽ x ⩽ 0.18 ) have been established via several controlled solid state reactions at 630 °C. X-ray diffraction and TEM investigations indicate that the diffraction patterns are dominated by diffuse scattering due to heavily faulted layer stacking. After several attempts crystals of better quality were obtained and studied. The structural refinements carried out on one selected crystal from a batch treated at 700 °C and annealed at 600 °C during 4 days presents a formula slightly richer in Mo6+ and V4+, corresponding to x ≈ 0.5 , i.e., Mo1.5V1.5O8. The main structural features are reported and analysed. The structure of these crystals is still affected by stacking defects, but in lower concentrations, leading to twinning phenomena. A detailed investigation by TEM and HREM of crystals corresponding to x = 0.15 confirms the drastic stacking disorder of these materials. Magnetic and electric measurements allow to ascribe the mixed valence formula, Mo6+1+xV5+2−2xV4+xO8 for these various compositions which shows a semi-conducting behaviour with an activation energy for x = 0.15 phase being E a = 0.22 eV .

The local structure of the H gl Ba 2 CaCu 2 O 6+δ (Hg1212) crystal has been investigated by temperature dependent polarized Cu K-edge extended x-ray absorption fine structure (EXAFS). We have observed an anomalous behavior of the local structure showing anomaly at around the superconducting transition temperature T c in the temperature dependence of the Cu-O(planar) distance. The result suggests similarity of the temperature dependent local instability in the superconducting cuprates.

A high precision X-ray diffraction analysis up to sin θ / λ = 1.15 of a HgBa 2 cuO 4+δ single crystal having a T c of ≈ 90 K is presented. The cell parameters are a = 3.8815(4), c = 9.485 (7) A . The refinements indicate the existence of a split barium site due to the presence of excess oxygen in the mercury layer. The position of this excess oxygen might be slightly displaced from the (1/2 1/2 0) position. A 6% mercury deficiency is observed. Models, including mercury defects, substitution by copper cations, or carbonate groups, are compared. However, we obtain no definite evidence for either of the three models. A possible disorder of the Hg position, due to the formation of chemical bonds with neighbouring extra oxygen anions, could correlate to the refinements of mixed species at the Hg site. A low temperature single crystal x-ray diffraction study, and comparison of refinements for the same single crystal with different extra oxygen contents, are in progress to help clarify this problem.

Unexpected out-of-hospital delivery accounts for 0.5% of the total number of delivery in France. The parturient is placed under constant multiparametric monitoring. Fetus heart rate is monitored thanks to fetal doppler. A high concentration mask containing a 50-to-50 percent mix of O(2) and NO performs analgesia. Assistance of mobile pediatric service can be required under certain circumstances such as premature birth, gemellary pregnancy, maternal illness or fetal heart rate impairment. Maternal efforts should start only when head reaches the pelvic floor, only if the rupture of the membranes is done and the dilation is completed. The expulsion should not exceed 30 min. Episiotomy should not be systematically performed. A systematic active management of third stage of labour is recommended. Routine care such as warming and soft drying can be performed when the following conditions are fulfilled: clear amniotic liquid, normal breathing, crying and a good tonus. Every 30 seconds assessment of heart rate, breathing quality and muscular tonus then guide the care. The redaction of birth certificate is a legal obligation and rests with the attending doctor.

Biocomposite hydrogels with carboxymethylated, nanofibrillated cellulose (c-NFC) powder were prepared by UV polymerization of N-vinyl-2-pyrrolidone with Tween 20 trimethacrylate as a cross-linking agent for replacement of the native, human nucleus pulposus (NP) in intervertebral disks. The swelling ratios and the moduli of elasticity in compression of neat and biocomposite hydrogels were evaluated in dependence of c-NFC concentration (ranging from 0 to 1.6% v/v) and degree of substitution (DS, ranging from 0 to 0.23). The viscoelastic properties in shear and the material relaxation behavior in compression were measured for neat and biocomposite hydrogels containing 0.4% v/v of fibrils (DS ranging from 0 to 0.23), and their morphologies were characterized by cryo-scanning electron microscopy (cryo-SEM). The obtained results show that the biocomposite hydrogels can successfully mimic the mechanical and swelling behavior of the NP. In addition, the presence of the c-NFC shows lower strain values after cyclic compression tests and consequently creates improved material relaxation properties compared with neat hydrogels. Among the tested samples, the biocomposite hydrogel containing 0.4% v/v of c-NFC with a DS of 0.17 shows the closest behavior to native NP. Further investigation should focus on evaluation and improvement of the long-term relaxation behavior.

The Airtraq optical laryngoscope (Vygon, Écouen, France) is a new intubation device designed to provide a view of the glottis without alignment of the oral, pharyngeal and laryngeal axes. In recent literature, the efficiency of the Airtraq even in difficult intubation and its short learning curve were characterized. The goal of our study is to evaluate Airtraq efficiency when use by inexperienced physicians in anticipated difficult intubation adult patients.The patients showing at least one of the four difficult intubation predictors (history of difficult intubation, thyromental distance less than 60mm, mouth opening less than 35 mm and Mallampati class 3 or 4 were included. Before induction of anaesthesia, the inexperienced physicians participating the study received a short oral formation on the use of the Airtraq. For each intubation manoeuvres, the participant were supervised by an expert in Airtraq handling. The Cormack and Lehane grade of direct laryngoscopy view, the duration times to best glottis view and to intubate the trachea, the success or failure of tracheal intubation, the drop in arterial oxygen saturation of below 95%, the need for external manipulation, and the difficulties met by the operators were noted.Twenty patients were included over a month period. Thirteen had a history of difficult intubation, eight a thyromental distance less than 60mm, nine a mouth opening less than 35 mm and 12 patients were classified as Mallampati IV. The success rate of tracheal intubation with the Airtraq laryngoscope was 80%. Times to best glottis view and to complete tracheal intubation were 28 and 47 s, respectively. Four tracheal intubation failures were encountered. The LMA Fastrach and the flexible fiberoscope were used respectively in one and three patients.In the majority of the cases, the insertion of the Airtraq, the visualization of the glottis and the subsequent intubation were easy and rapid, without arterial oxygen desaturation. However, the four tracheal intubation failures associated with prolonged tracheal intubation times in some patients highlight the fact that the Airtraq laryngoscope requires a clinical training process particularly in case of anticipated difficult airway management situations.

We present the first application of pulsed high magnetic fields up to 30 T for neutron diffraction experiments. As the first study, field variations of a couple of magnetic Bragg reflections have successfully been measured in the frustrated antiferromagnet ${\mathrm{TbB}}_{4}$. The results show that the conventional models fail, and a model, which is a mixture of the $XY$- and the Ising-type moments, matches for the half-magnetization state. We deduce an interaction that stabilizes an orthogonal moment arrangement as an origin of the unusual magnetization plateaus. Our results demonstrate the powerfulness of the present pulsed magnetic fields neutron diffraction system.

We report the determination of the Dzyaloshinsky-Moriya interaction, the dominant magnetic anisotropy term in the kagome spin-1/2 compound ZnCu3(OH)6Cl2. Based on the analysis of the high-temperature electron spin resonance (ESR) spectra, we find its main component |Dz|=15(1) K to be perpendicular to the kagome planes. Through the temperature dependent ESR linewidth, we observe a building up of nearest-neighbor spin-spin correlations below approximately 150 K.

We report, through 17O NMR, an unambiguous local determination of the intrinsic kagome lattice spin susceptibility as well as that created around nonmagnetic defects arising from natural Zn/Cu exchange in the S=1/2 (Cu2+) herbertsmithite ZnCu3(OH)6Cl2 compound. The issue of a singlet-triplet gap is addressed. The magnetic response around a defect is found to markedly differ from that observed in nonfrustrated antiferromagnets. Finally, we discuss our relaxation measurements in the light of Cu and Cl NMR data and suggest a flat q dependence of the excitations.

A new vanadium molybdenum mixed oxide V1.1Mo0.9O5 [V(V)0.2V(IV)0.9Mo(VI)0.9O5] has been synthesized, as a pure phase, via hydrothermal methods in the presence of molybdic acid and vanadyl sulfate. Its crystal structure has been solved ab initio from high-resolution powder diffraction data collected at the ESRF beamline ID31. This compound crystallizes in the monoclinic symmetry, space group C2/m, with cell dimensions a = 12.1230 ( 2 ) A , b = 3.7168 ( 1 ) A , c = 4.0336 ( 1 ) A , β = 90.625 ( 3 ) ° and Z = 2 per formula. The structure consists of double strings of VO5 square pyramids sharing edges and corners along [100] and [010], and more weakly bound along [001]. In this latter direction, the bond (V,Mo)–O=2.377 A, while remaining long, leads for the first time to the interpenetration of the apical oxygens of the [(V,Mo)2O5]n layers, resulting in a three-dimensional (3D) structure closely related to R-Nb2O5. This structure will be compared to the pure layer structure of V2O5 where this bond reaches 2.793 A.

Volborthite Cu 3 V 2 O 7 ( OH ) 2 · 2 H 2 O is a natural frustrated antiferromagnet with a kagome-like magnetic lattice decorated by S = 1 2 spins. Our μ SR results confirm the existence of a dynamical plateau below 2 K, as initially demonstrated in [Phys. Rev. Lett. 91 (2003) 207603] despite sensible quantitative differences in the relaxation rate values. Thanks to additional low temperature SQUID and NMR data we show that this plateau occurs concurrently with a freezing transition. Moreover, we revisited the effect of diluting the magnetic lattice for small dilution rates between 1% and 15%. Comparison is made with the well studied kagome bilayer compounds. The ground state of volborthite appears to be far less stable with respect to dilution.

The volborthite compound is one of the very few realizations of S=1/2 quantum spins on a highly frustrated kagomé-like lattice. Low-T SQUID measurements reveal a broad magnetic transition below 2 K which is further confirmed by a peak in the 51V nuclear spin relaxation rate (1/T1) at 1.4 K +/- 0.2 K. Through 51V NMR, the ground state (GS) appears to be a mixture of different spin configurations, among which 20% corresponds to a well defined short-range order, possibly of the sqrt(3) x sqrt(3) type. While the freezing involves all the Cu2+ spins, only 40% of the copper moment is actually frozen which suggests that quantum fluctuations strongly renormalize the GS.

International audience; Bi 7−x As 1+x Mo 3 O 21 (0 x 1) a new pillar structure type: synthesis, crystal structure and conductivity Abstract An original structure of chemical formula Bi 13 As 3 Mo 6 O 42 has been obtained in the system Bi 2 O 3 :MoO 3 :As 2 O 3 by chemical transport reaction in presence of As 2 O 3. It crystallizes in the monoclinic system, space group P 2 1 /n with a = 12.7770(11) Å, b = 5.5890(4) Å, c = 27.971(2) Å and β = 101.009(7) •. The structure exhibits infinite [Bi 13 As 3 Mo 6 O 42 ] n complex pillars with a quite different organization compared with original [Bi 12 O 14 ] 8n+ n columns surrounded by (MoO 4) tetrahedra in the Bi 2/3 [Bi 12 O 14 ](MoO 4) 5 prototype structure. Nevertheless, the heavy atoms design almost perfect fluorite subnetwork-a common structural feature of these pillar structures. The conditions of synthesis via solid-state chemistry using basic oxides Bi 2 O 3 , As 2 O 3 and MoO 3 have been established and the phase identified by X-ray powder pattern. The indexing fits single crystal data as well as the values of volumic mass, ρ exp = 7.04(4) g cm −3 for ρ X = 7.096 g cm −3 for Z = 4. This Bi 13 As 3 Mo 6 O 42 phase shows also an interesting anionic conductivity around σ = 7.98 × 10 −4 S cm −1 at 980 K and is compared with related phases.  2004 Elsevier SAS. All rights reserved.

International audience; In this work, we report on low-temperature x-ray diffraction, electron-spin-resonance and magnetic-susceptibility measurements performed on η-Na1.286V2O5. We show that the low-temperature structure of this compound differs from that at room temperature mainly by the doubling of the unit cell in the b direction. The magnetic measurements give evidence for the opening of a spin gap which we discuss in conjunction with the low-temperature structure of this compound.

In this work, we report on x-ray diffraction, electron spin resonance, and magnetic susceptibility measurements performed on η-Na 1 . 2 8 6 V 2 O 5 . The x-ray data clearly reveal the existence, around 100 K, of a structuralsecond-order phase transition, stabilizing a superstructure associated with charge ordering. The complete superstructure is determined from x-ray scattering data measured at 15 and 40 K. The low-temperature structure remains centrosymmetric with space group P2/c but with a doubled b lattice parameter. An analysis using superspace symmetry shows that one of the vanadium atoms and its apical oxygen, namely the V7 and 07 atoms, are the most displaced. Two sites for V7 atoms are identified below the transition instead of one with the formal valence of V 4 . 5 + . We show that these two sites are occupied by V 4 + and V 5 + , which corresponds to a charge ordering. We suggest that this transition is driven by electronic repulsions. The magnetic measurements give additional evidence for this transition and for the opening of a spin gap at low temperature. This is discussed in conjunction with superstructure formation.

Analytical formulae for de Haas-van Alphen (dHvA) oscillations in linear chain of coupled two-dimensional (2D) orbits (Pippard's model) are derived systematically taking into account the chemical potential oscillations in magnetic field. Although corrective terms are observed, basic (alpha) and magnetic breakdown-induced (beta and 2beta - alpha) orbits can be accounted for by the Lifshits-Kosevich (LK) and Falicov-Stachowiak semiclassical models in the explored field and temperature ranges. In contrast, the 'forbidden orbit' beta - alpha amplitude is described by a non-LK equation involving a product of two classical orbit amplitudes. Furthermore, strongly non-monotonic field and temperature dependence may be observed for the second harmonics of basic frequencies such as 2alpha and the magnetic breakdown orbit beta + alpha, depending on the value of the spin damping factors. These features are in agreement with the dHvA oscillation spectra of the strongly 2D organic metal theta- theta-(ET)(4)CoBr(4)(C(6)H(4)Cl(2)).

The structure of HgBa 2 CuO 4+δ is studied as function of temperature by neutron diffraction and Cu-Kedge EXAFS on the same powder sample with Tc=97K. Both techniques reveal the presence of an anomalous behaviour of the Cu O in-plane bond length starting at ≈140K.

The mechanical and damping properties were measured for unidirectional, 0/90 and twill 2/2 flax fibre (FF) composites containing 40 vol% of fibres in an epoxy matrix. All composites were processed by resin transfer moulding. The influence of the impregnation quality, the fibre/matrix adhesion, the quality of the fibres, the twist angle of the FF yarns and the crimp in the FF fabrics on these properties were quantified. Twisted yarns in an unidirectional FF fabric impacted negatively on the stiffness while increasing the damping of about 57% through enhancement of the intra-yarn friction. In twill 2/2 fabrics, twisted yarns decreased Young's modulus owing to the induced crimp but increased the damping through enhanced inter-yarn friction. With improved fibre/matrix adhesion, a damping increase up to 109% was obtained through better activation of the intrinsic damping mechanisms of an elementary FF. The best compromise between damping and stiffness was obtained with FF having less dislocations.