Spatial structure and composition of polysaccharide-protein complexes from Small Angle Neutron Scattering

We use Small Angle Neutron Scattering (SANS), with an original analysis method, to obtain both the characteristic sizes and the inner composition of lysozyme-pectin complexes depending on the charge density. Lysozyme is a globular protein and pectin a natural anionic semiflexible polysaccharide with a degree of methylation (DM) 0, 43 and 74. For our experimental conditions (buffer ionic strength I = 2.5 10-2 mol/L and pH between 3 and 7), the electrostatic charge of lysozyme is always positive (from 8 to 17 depending on pH). The pectin charge per elementary chain segment is negative and can be varied from almost zero to one through the change of DM and pH. The weight molar ratio of lysozyme on pectin monomers is kept constant. The ratio of negative charge content per volume to positive charge content per volume, -/+, is varied between 10 and 0.007. On a local scale, for all charged pectins, a correlation peak appears at 0.2 {\AA}-1 due to proteins clustering inside the complexes. On a large scale, the complexes appear as formed of spherical globules with a well defined radius of 10 to 50 nm, containing a few thousands proteins. The volume fraction Phi of organic matter within the globules derived from SANS absolute cross-sections is around 0.1. The protein stacking, which occurs inside the globules, is enhanced when pectin is more charged, due to pH or DM. The linear charge density of the pectin determines the size of the globules for pectin chains of comparable molecular weights whether it is controlled by the pH or the DM. The radius of the globules varies between 10 nm and 50 nm. In conclusion the structure is driven by electrostatic interactions and not by hydrophobic interactions. The molecular weight also has a large influence on the structure of the complexes since long chains tend to form larger globules. This maybe one reason why DM and pH are not completely equivalent in our system since DM 0 has a short mass, but this may not be the only one. For very low pectin charge (-/+ = 0.07), globules do not appear and the scattering signals a gel-like structure. We did not observe any beads-on-a-string structure

Twenty-five years of geodetic measurements along the Tadjoura-Asal rift system, Djibouti, East Africa

International audienceSince most of Tadjoura-Asal rift system sits on dry land in the Afar depression near the triple junction between the Arabia, Somalia, and Nubia plates, it is an ideal natural laboratory for studying rifting processes. We analyze these processes in light of a time series of geodetic measurements from 1978 through. A network of about 30 GPS sites covers the Republic of Djibouti. Additional points were also measured in Yemen and Ethiopia. Stations lying in the Danakil block have almost the same velocity as Arabian plate, indicating that opening near the southern tip of the Red Sea is almost totally accommodated in the Afar depression. Inside Djibouti, the Asal-Ghoubbet rift system accommodates 16 ± 1 mm/yr of opening perpendicular to the rift axis and exhibits a pronounced asymmetry with essentially null deformation on its southwestern side and significant deformation on its northeastern side. This rate, slightly higher than the large-scale Arabia-Somalia motion (13 ± 1 mm/yr), suggests transient variations associated with relaxation processes following the Asal-Ghoubbet seismovolcanic sequence of 1978. Inside the rift, the deformation pattern exhibits a clear two-dimensional pattern. Along the rift axis, the rate decreases to the northwest, suggesting propagation in the same direction. Perpendicular to the rift axis, the focus of the opening is clearly shifted to the northeast, relative to the topographic rift axis, in the ''Petit Rift,'' a rift-in-rift structure, containing most of the active faults and the seismicity. Vertical motions, measured by differential leveling, show the same asymmetric pattern with a bulge of the northeastern shoulder. Although the inner floor of the rift is subsiding with respect to the shoulders, all sites within the rift system show uplift at rates varying from 0 to 10 mm/yr with respect to a far-field reference outside the rift

Time of flight spectrometry studies of graphite surface : ultrafast laser ablation and photoelectron spectroscopy

This work reports an investigation of the interaction of ultrashort laser pulses with a graphite surface. Time-of-flight experiments were conducted with a 100 fs laser system, then 13 fs laser pulses at 800 nm wavelength were used for photoelectron spectroscopy studies. Multi-shots and single-shot laser pulse regimes have shown the existence of two mechanisms involved in the ablation of graphite: at low laser fluence, a non-thermal physical process known as Coulomb explosion (CE) is responsible for the ultrafast removal of particles. At high laser fluence, a thermal process, called plasma generation and characterized by a liquid-carbon phase initiated by the laser pulse, takes place and is believed to be at the origin of the ejection of particles. On the other hand, results from 13 fs laser pulses give rise to unusual high kinetic energy photoelectron around 20 eV that cannot be explained by the multiphoton ionization process but by tunnel and/or above barrier ionization (ABI). This unexpected result at such low intensities (10¹⁰ < I(W/cm²) <10¹²) is interpreted as a roughening of the surface by the laser pulse that leads to photon-plasmon coupling, then an enhancement of the local electric surface field enough to make possible electrons tunneling through the potential barrier or even to escape directly (ABI) into the vacuum.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

La cresme philosophale des questions enciclopédiques de Pantagruel (un opuscule chimérique dans la bataille des arts)

Que nous dit sur la tradition des Œuvres de Rabelais, La Cresme philosophalle, curieux opuscule ajouté à la fin des éditions parues après la mort de l écrivain ? Et comment le lire ? Telles sont les deux questions examinées dans cette thèse. Dans la première partie, en est retracée la réception critique (XVIIe-XXe s.), puis la tradition éditoriale dans les éditions du XVIe siècle. La question de l'attribution donne ensuite lieu à trois hypothèses : l'authenticité complète, l'attribution partielle (opuscule traduit), enfin, l'inauthenticité. Dans la deuxième partie, après avoir décrit les enjeux et les espèces de la quaestio, genre dont relève cet opuscule, et qui appartient à l'histoire de la scolastique, est retracée la tradition des critiques dont celle-ci fait l'objet dans le cadre de la bataille des arts, puis lors la polémique frontale des premiers temps de la Réforme. Ensuite, en contre-champ, sont considérés plusieurs opuscules de nature parodique, appartenant à la production festive des clercs, toujours en rapport avec la quaestio. Pour finir, l étude interne puis la comparaison de cet opuscule avec l'ensemble des textes précédemment considérés permettent d affirmer qu'il s'agit d'un opuscule, aux confins de plusieurs sphères de discours, reposant sur une stratégie parodique. Plusieurs procédés sont en outre conformes à l'utilisation rabelaisienne de la figure. Surtout, cet opuscule confirme la nécessité de rapprocher sinon croiser histoire littéraire et histoire de l'Université. Cette étude est suivie de la première édition critique de cet opuscule, suivie d appendices, contenant plusieurs opuscules inédits en français.The Philosophical Cream is a curious opuscule added to the end of the editions published after its author's death: what does it tell us about the tradition of The Works of Rabelais ? And how should we read it ? These are the two questions that are discussed in this thesis. In the first part, we have retraced its critical reception (17th-20th c.), then its editorial tradition in the editions of the 16th century. After which, the issue of its attribution gives place to three hypotheses : the complete authenticity, the partial attribution (translated opuscule) and, finally, the unauthenticity. In the second part, after describing the stakes involved and the different types of quaestio - the genre to which this opuscule pertains, belonging to the history of scholasticism -, the tradition of criticisms is discussed, this being the object in the frame of the battle of arts, since then a frontal debate in the Reformation times. Then, as an anticlimax, several opuscules of parodic nature are discussed, as belonging to the festive production of clergymen, always in relation with the quaestio. Finally, the internal study as well as the comparison between these data and the previously examined texts enable us to state that the work is an opuscule, at the borderline of several discourse spheres, lying on a strategy of mimetic satire. Several procedures are consistent with the Rabelaisian use of figures. But this opuscule in particular confirms the necessity to confront the history of literature with the history of University. The study is complemented by the first critical edition of this opuscule, followed by wide appendixes containing several other opuscules, remained unpublished in French.PARIS4-BU Serpente (751052129) / SudocSudocFranceF

Maîtrise de la contamination des fontaines réfrigérantes par

Des fontaines réfrigérantes sont installées dans les établissements de santé afin de procurer une eau de boisson rafraichie et désaltérante. Dans ce but, elles sont utilisées par les soignants et par les patients. Le nettoyage de ces fontaines, leur maintenance et leur surveillance font intervenir des professionnels soignants, techniques et les hygiénistes. Dans le cadre d’une gestion rigoureuse et selon réglementation, des analyses bactériologiques sur toutes les fontaines réfrigérantes de l’hôpital sont réalisées pluri-annuellement. Dans cette étude, 3 fontaines sur 26 sont contaminées par Pseudomonas aeruginosa. Cette contamination est problématique et peut entraîner des infections nosocomiales chez les patients les plus fragiles. La recherche des causes de la contamination montre qu’elle ne provient pas du réseau d’eau de l’hôpital et que la fontaine réfrigérante incriminée n’est pas contaminée. Nous avons trouvé que la colonisation par P. aeruginosa s’effectue dans le tuyau de jonction entre le réseau d’eau froide et la fontaine. Les différents moyens de maîtriser cette situation ont été le détartrage, les interventions techniques internes et le changement du tuyau de jonction

Nebulization is less effective than aerosolization, in PIPAC live animal drug delivery testing

International audienc

Tectonic Evolution of a Sedimented Oceanic Transform Fault: The Owen Transform Fault, Indian Ocean

The Owen transform fault (OTF) connecting the Sheba and the Carlsberg spreading ridges in the Indian Ocean currently forms the active plate boundary between India and Somalia plates. This 330-km-long transform fault is by far the longest transform fault along the India-Somalia plate boundary and its valley is buried under the thick distal turbidites of the Indus Fan with total thickness ranging from 1,000 to >5,000 m. A new set of seismic reflection and multibeam bathymetric data reveals remarkable transpressive structures along its entire length recorded as folds in the sedimentary cover, eruption of mud ridges at the seafloor, thrusts in the young oceanic lithosphere. Based on a new regional time-calibration of the seismic reflectors, we show that sediments in the transform valley (post 8.6 Ma) recorded a period of tectonic quiescence until the onset of a transpressive event around 1.5–2.4 Ma that we relate to a minor change in India-Somalia kinematics not captured by magnetic anomalies. This tectonic regime is still active based on compressive earthquakes and deformation of the most recent sediments. Transpression resulted in the formation of a proto-median ridge and the coeval propagation of the tip of the Carlsberg Ridge into the Somalian plate. These features are typically encountered at many other transform faults but rarely captured in their very early stag

The Magnetic Signature of Oceanic Core Complexes

International audienceOceanic core complexes (OCC) are widespread tectonic features on slow spreading centers. They involve a steep detachment fault rooted on the neovolcanic zone that evolves to a flat, often exhumed detachment surface away from the axis. Their magnetic signature has so far been poorly defined: only few magnetic surveys exist and their interpretation is complex due to the multiple rock types, insufficient coverage and resolution and, for the best studied OCCs on the MAR 13-15°N, location-N-S trending magnetized features near the magnetic Equator generate negligible anomalies. We take advantage of two recent surveys to constrain the magnetic signature of OCCs. (1) Cruise CARLMAG of BHO Beautemps-Beaupré (2019) surveyed several large OCCs of the NE-SW trending Carlsberg Ridge and depicted clear sea-surface anomalies that unambiguously record geomagnetic reversals, pointing out that the oceanic crust created on large OCCs also bears the seafloor spreading magnetic stripes. As expected, the axial anomaly extends from the axial valley over a large part of the OCC, this large shift with respect to the axial valley confirming that most seafloor spreading is accounted by the detachment fault motion. Possible sources for the magnetic anomalies include gabbro bodies cooled in the neovolcanic zone and carried off-axis as the footwall progressively exhumes, or serpentinite formed near the axis as mantle peridotite cools below ~400°C and is altered by hydrothermal circulation. (2) During Cruise ODEMAR of R/V Pourquoi Pas? (2013), AUV Abyss achieved a detailed bathymetric and magnetic survey of the 13°20'N OCC at altitude ~70 m. Although the OCC presumably formed within the Brunhes chron, the magnetic data inverted to equivalent magnetization reveal a clear magnetic stripe that may reflect geomagnetic variations recorded by seafloor spreading. The sharp limits of this anomaly favor cooled gabbro bodies as the source for the magnetic anomalies observed at OCCs

Pressurized intra-peritoneal aerosol chemotherapy (PIPAC): increased intraperitoneal pressure does not affect distribution patterns but leads to deeper penetration depth of doxorubicin in a sheep model

International audiencePressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC) is an innovative treatment against peritoneal carcinomatosis. Doxorubicin is a common intravenous chemotherapy used for peritoneal carcinomatosis and for PIPAC. This study evaluated the impact of increased PIPAC intraperitoneal pressure on the distribution and cell penetration of doxorubicin in a sheep model.Doxorubicin was aerosolized using PIPAC into the peritoneal cavity of 6 ewes (pre-alpes breed): N = 3 with 12 mmHg intraperitoneal pressure ("group 12") and N = 3 with 20 mmHg ("group 20"). Samples from peritoneum (N = 6), ovarian (N = 1), omentum (N = 1) and caecum (N = 1) were collected for each ewe. The number of doxorubicin positive cells was determined using the ratio between doxorubicine fluorescence-positive cell nuclei (DOXO+) over total number of DAPI positive cell nuclei (DAPI+). Penetration depth (μm) was defined as the distance between the luminal surface and the location of the deepest DOXO+ nuclei over the total number of cell nuclei that were stained with DAPI. Penetration depth (μm) was defined as the distance between the luminal surface and the location of the deepest DOXO+ nuclei.DOXO+ nuclei were identified in 87% of samples. All omental samples, directly localized in front of the nebulizer head, had 100% DOXO+ nuclei whereas very few nuclei were DOXO+ for caecum. Distribution patterns were not different between the two groups but penetration depth in ovary and caecum samples was significantly deeper in group 20