Couplage diffusion d'humidité/ états mécaniques internes dans les polymères et composites - une approche thermodynamique

International audienceNous utilisons une approche thermodynamique, basée sur la définition du potentiel chimique de l'eau, pour établir un modèle couplant la diffusion de l'humidité aux états mécaniques d'un polymère. Le modèle permet de prendre en compte les évolutions, au cours du processus de diffusion, de la masse volumique du polymère et de la capacité maximale d'absorption d'humidité aux frontières. L'approche développée peut s'appliquer à des cas de chargement dissymétriques en termes d'humidité et de pression extérieure. Le modèle ainsi établi permet, entre autres, de prédire les profils de teneur en eau dans l'épaisseur du polymère, tout au long de la phase transitoire du processus de diffusion. Les résultats obtenus montrent l'effet considérable, induit par l'application d'une pression extérieure, sur la cinétique de diffusion de l'humidité dans les polymères

Does advancing male age influence the expression levels and localisation patterns of phospholipase C zeta (PLCζ) in human sperm?

Socio-economic factors have led to an increasing trend for couples to delay parenthood. However, advancing age exerts detrimental effects upon gametes which can have serious consequences upon embryo viability. While such effects are well documented for the oocyte, relatively little is known with regard to the sperm. One fundamental role of sperm is to activate the oocyte at fertilisation, a process initiated by phospholipase C zeta (PLCζ), a sperm-specific protein. While PLCζ deficiency can lead to oocyte activation deficiency and infertility, it is currently unknown whether the expression or function of PLCζ is compromised by advancing male age. Here, we evaluate sperm motility and the proportion of sperm expressing PLCζ in 71 males (22–54 years; 44 fertile controls and 27 infertile patients), along with total levels and localisation patterns of PLCζ within the sperm head. Three different statistical approaches were deployed with male age considered both as a categorical and a continuous factor. While progressive motility was negatively correlated with male age, all three statistical models concurred that no PLCζ–related parameter was associated with male age, suggesting that advancing male age is unlikely to cause problems in terms of the sperm’s fundamental ability to activate an oocyt

Anti-müllerian hormone levels and evolution in women of reproductive age with breast cancer treated with chemotherapy

International audienceBackground: Long-term consequences of cancer treatments in young women, and especially fertility issues, are gaining attention as survival rates increase. Breast cancer is the most frequent malignancy in women of reproductive age.Aim: The purpose of this review is to describe serum anti-mü llerian hormone (AMH) level at diagnosis and its evolution during and after chemotherapy in women of reproductive age treated for breast cancer. Second, the impact of taxanes on AMH, the association between AMH and amenorrhea, and the comparison of AMH with other hormonal markers of ovarian reserve were studied.Methods: A systematic PubMed search was conducted on all articles, published up to April 2016 and related to AMH in women suffering from breast cancer using the following key words: AMH, mü llerian-inhibiting substance, ovarian reserve, ovarian function, breast cancer, gonadotoxicity, ovarian toxicity, amenorrhea, chemotherapy, and menopause.Results: AMH levels rapidly fall down to undetectable levels in most women during chemo-therapy and generally persist at very low levels in most women after the treatment. Taxanes seem to impact negatively ovarian function, but data on ovarian reserve are scarce. AMH is a predictor of the occurrence of chemotherapy-related amenorrhea and is the most relevant hormonal marker of ovarian reserve.Conclusion: Serum AMH is a relevant tool for ovarian reserve assessment and follow-up during treatment in premenopausal women with breast cancer. Further large prospective studies are necessary to determine its predictive interest for post-treatment residual fertility, and eventually use it in fertility preservation counseling before treatment initiation

Synchronous Multimodal Measurements on Lips and Glottis: Comparison Between Two Human-Valve Oscillating Systems

International audienceThe brass instrument-player and the human voice production systems are both composed of a vibrating " human valve " coupled to an acoustic resonator and can be modelled by very similar dynamical systems. Moreover, lips and glottis are both difficult to access during sound production without disturbing their mechanical behaviour and vibration characteristics. In this article, we introduce a common measurement and analysis framework in order to study and compare the vibration of lips and glottis during sound production. Based on previous studies conducted on vibrating vocal folds, our measurement system is composed of three synchronous measurements –electrical admittance (electroglottography and electrolabiography), high-speed video recording and sound recording– and allows relatively non-intrusive measurements to be performed on singers and trombone players. Analysis of the collected data highlights the interpretability of electrolabiographic signals. Furthermore, similarities and differences between the two valve systems are investigated with regard to high speed imaging, electrical admittance and basic characteristics of the radiated sound

Characterisation of the hygro-thermo-mechanical behaviour of organic matrix composites instrumented with optical fibres: A study of interfacial bonding

International audienceMoisture diffusion can decrease the mechanical stiffness and strength of organic matrix composites. Recently, Fibre Bragg Grating (FBG) sensors have been used in order to study the hygroscopic ageing of polyester/glass composites at room temperature. In the present study, the hygroscopic strain measurement of polyester/glass composite has been achieved at room temperature. Furthermore, measurements have been done at higher temperatures in order to better understand the combination of both hygroscopic ageing and varying temperatures on the mechanical properties of these composite samples. The Bragg wavelength (λbλb) was found to shift linearly over a temperature range from room temperature to 35 °C. Beyond 35 °C, the Bragg wavelength does not linearly vary as a function of the temperature. A strong variation of the Bragg wavelength above a specific temperature threshold was found. This could be explained according to two mechanisms. Firstly, hygroscopic ageing could result in a decrease of the glass transition temperature (Tg) of the polymer matrix. Therefore viscoelastic behavior may appear beyond this temperature. Hygroscopic ageing could also degrade the interfacial shear strength between the fibre and the resin. Differential Scanning Calorimetry (DSC) analyses showed that hygroscopic aging does not affect the Tg of the polyester resin. Furthermore, it has been found that the hygroscopic aging degrades the interfacial adhesion of the optical fibre/polyester according to the considerable decreases of the interfacial shear strength observed in practic

The magnetic field of the chemically peculiar star V352 Peg

International audienceWe present a spectropolarimetric analysis of the hot star V352 Peg. We have acquired 18 spectropolarimetric observations of the star with ESPaDOnS at the CFHT between 2018 and 2019 and completed our dataset with one archival ESPaDOnS measurement obtained in 2011. Our analysis of the spectra shows that the star is on the main sequence and chemically peculiar, i.e. it is a Bp star, with overabundances of iron peak elements (Ti, Cr and Fe) and underabundance of He and O. Through a Least-Square Deconvolution of each spectrum, we extracted the mean Zeeman signature and mean line profile of thousands of spectral lines and detected a magnetic field in V352 Peg. By modelling the Stokes I and V profiles and using the Oblique Rotator Model, we determined the geometrical configuration of V352 Peg. We also performed Zeeman-Doppler Imaging (ZDI) to provide a more detailed characterization of the magnetic field of V352 Peg and its surface chemical distributions. We find a magnetic field that is mainly dipolar, dominantly poloidal, and largely non-axisymmetric with a dipole field strength of ~9 kG and a magnetic axis almost perpendicular to the rotation axis. The strong variability of Stokes I profiles also suggests the presence of chemical spots at the stellar surface

Hygroscopic strain measurement by fibre Bragg gratings sensors in organic matrix composites – Application to monitoring of a composite structure

International audienc

Sperm cryopreservation and assisted reproductive technology outcome in patients with spinal cord injury

International audienceThis study aimed to describe spinal cord injured patients' semen characteristics before and after cryopreservation, and assisted reproductive technology cycles outcome compared to the infertile population. Data about sperm analysis and assisted reproductive technology (ART) cycles outcomes for 78 men with spinal cord injury referred for sperm cryopreservation between 1998 and 2013 were retrospectively analysed and compared with a reference group consisting of every Intra Cytoplasmic Sperm Injection (ICSI) cycle performed in our in vitro fertilization unit over the 2009-2014 period. Semen was collected by penile vibratory stimulation (PVS), electroejaculation or via testis biopsies. Fresh and frozen semen parameters and ART outcomes with frozen-thawed sperm were measured. Patients were divided into three groups according to the sperm retrieval methods: 37 electroejaculations, 37 PVSs and four surgical sperm retrievals. Low ejaculate volume was observed in 33% of the patients, and oligozoospermia in 37% of the patients. Specimens from 77 of the patients contained motile sperm and were therefore frozen for future use. There was no statistical difference for any of the fresh semen parameters between all groups. Twenty of them underwent ICSI leading to five live births, while four underwent intrauterine insemination. ART with frozen-thawed spermatozoa can provide men with SCI with comparable results as in the infertile population

Semen cultures analysis: retrospective study during a 6-year period and interest in the management of infertility

International audienceIn the past decade, the number of couples consulting an assisted reproductive techniques (ART) center for infertility has increased in most European countries. In France, sperm bacterial examination must be performed every 6 months in couples undergoing in vitro fertilization (IVF) cycles, according to 2010 French ART Guidelines. The aim of this study was to analyze the results from such samples at Nantes University Hospital and to assess their potential value for infertile couples undergoing ART cycles. Between 2003 and 2008, semen cultures performed were analyzed according to bacterial enumeration, type and number of bacterial species, and their antibiotic resistance profile. A total of 14,119 semen cultures were performed, showing an annual increase of 45% from the start to the end of the study. The proportion of positive semen cultures was stable throughout the study period (40 to 45%). Many bacterial species were considered as contaminants (coagulase-negative staphylococci, alpha-hemolytic streptococci). For pathogen agents (in most cases, Enterobacteriaceae), the antibiotic resistance profile revealed mostly a susceptible phenotype. Finally, every positive bacterial result had direct consequences on the IVF cycle management, with subsequent reinforced advice on the hygiene procedure before sample collection and/or antibiotics prescription