Intrusion and extrusion of water in hydrophobic mesopores

We present experimental and theoretical results on intrusion-extrusion cycles of water in hydrophobic mesoporous materials, characterized by independent cylindrical pores. The intrusion, which takes place above the bulk saturation pressure, can be well described using a macroscopic capillary model. Once the material is saturated with water, extrusion takes place upon reduction of the externally applied pressure; Our results for the extrusion pressure can only be understood by assuming that the limiting extrusion mechanism is the nucleation of a vapour bubble inside the pores. A comparison of calculated and experimental nucleation pressures shows that a proper inclusion of line tension effects is necessary to account for the observed values of nucleation barriers. Negative line tensions of order $10^{-11} \mathrm{J.m}^{-1}$ are found for our system, in reasonable agreement with other experimental estimates of this quantity

Decreased Sialidase Activity in Alveolar Macrophages of Guinea Pigs Exposed to Coal Mine Dust

International audienceThe origin of immune dysfunctions that are observed in pneumoconiotic miners still remains unknown. There is evidence that the carbohydrate moiety of membrane glycoconjugates is of primary importance in many functions of immunocompetent cells. The glycosylation, and especially the sialylation level of membrane components of various lymphocyte and macrophage subsets, vary depending on the state of cellular differentiation and activation. Sialidases, which may regulate the amount of sialic acids exposed on the cell membrane, can thus be considered as immunoregulatory enzymes. In this report, the sialidase activity has been measured in alveolar macrophages (AM) and in cell-free bronchoalveolar lavage fluid (BALF) from guinea pigs exposed for 4 months to coal mine dust at a concentration of 300 mg/m3. The samples were collected by bronchoalveolar lavage 2 months after cessation of exposure. The sialidase activity in the cell-free fluid and in the purified alveolar macrophages showed a 10-fold decrease (p < 0.001). Kinetic parameters of the enzyme such as K(m) and optimum pH did not change. This changed activity was specific for sialidase, as two other lysosomal glycosidases, beta-galactosidase and N-acetylglucosaminidase, showed unchanged activities. These results suggest the possibility that, by inducing a decreased sialidase activity, exposure to coal mine dust may lead to a modified expression of AM membrane-associated sialic acids giving rise to altered immune functions (i. e., phagocytosis, antigen processing response to cytokines, etc.)

Synthesis, Structure and Electrochemical Behavior of New RPONOP (R = tBu, iPr) Pincer Complexes of the Fe2+, Co2+, Ni2+ and Zn2+ ions.

International audienceThe coordination chemistry of the M2+ ions of the first row elements iron, cobalt, nickel and zinc was explored with the ligands RPONOP (2,6-(R2PO)(C5H3N), R = iPr and tBu). Syntheses and characterization of the complexes Fe(RPONOP)Br2, Co(tBuPONOP)Cl2, Ni(RPONOP)I2 and Zn(RPONOP)I2 (R = tBu, iPr) are reported together with the crystal structures of Fe(RPONOP)Br2 (R = iPr and tBu), Co(tBuPONOP)Cl2, Co(iPrPONOP)Cl(m-Cl)CoCl2(THF), Ni(iPrPONOP)I2, Zn(iPrPONOP)I2 and of the oxidation product Zn[tBuP(=O)ONOP(=O)]I2 resulting from reaction with oxygen. The electrochemical behavior of the M(tBuPONOP)X2 complexes has been investigated in acetonitrile. While the nickel compound is stable, all the complexes are sensitive to dissociation of the RPONOP ligand or ligand scrambling in strongly coordinating media. Catalytic activity in formic acid dehydrogenation with TONs up to 1143 has been found for Ni(tBuPONOP)I2

Decrease in ovalbumin-induced pulmonary allergic response by benzaldehyde but not acetaldehyde exposure in a guinea pig model

International audienceThe pulmonary effects of two environmentally relevant aldehydes were investigated in non-sensitized or ovalbumin (OA)-sensitized guinea pigs (GPs). Four-week-old male Hartley GPs, weighing about 400 g, were intraperitoneally injected with 1 ml of an NaCl solution containing 100 mug OA and 100 mg Al/(OH)(3). They were then exposed to either acetaldehyde (200 ppb) or benzaldehyde (500 ppb) (or 4 wk (6 h/d, 5 d/wk). At the end of exposure, GPs were challenged with an OA aerosol (0.1% in NaCl) and pulmonary functions were measured. The day after, guinea pigs were anesthetized and several endpoints related to inflammatory anti allergic responses were assessed in blood, whole-lung histology, and bronchoalveolar lavage (BAL). Sensitized nonexposed GPs showed bronchial hyperresponsiveness to OA and an increased number of eosinophils in blood and BAL, together with a rise in total protein and leukotrienes (LTB4 and LTC4/D-4/E-4) in BAL. In nonsensitized GPs, exposure to acetaldehyde or benzaldehyde did not induce any change in the tested parameters;, with the exception of irritation of the respiratory tract as detected by histology and an increased number of alveolar macrophages in animals exposed to acetaldehyde. In sensitized GPs, exposure to acetaldehyde induced a moderate irritation of the respiratory tract but no change in biological parameters linked to the inflammatory and allergic responses, In contrast, exposure to benzaldehyde induced a decrease both in OA-induced bronchoconstriction and in eosinophil and neutrophil numbers in BAL, an increase in the bronchodilatator mediator prostaglandin E-2 (PGE(2)) and a decrease in the bronchoconstrictor mediators LTC4/D-4/E-4. Further investigations are needed to determine if the attenuated response observed in sensitized GPs exposed to benzaldehyde is due to an alteration of the mechanism of sensitization or to a more direct effect on various mechanisms of the allergic response

Semi-empirical dissipation source functions for ocean waves: Part I, definition, calibration and validation

New parameterizations for the spectra dissipation of wind-generated waves are proposed. The rates of dissipation have no predetermined spectral shapes and are functions of the wave spectrum and wind speed and direction, in a way consistent with observation of wave breaking and swell dissipation properties. Namely, the swell dissipation is nonlinear and proportional to the swell steepness, and dissipation due to wave breaking is non-zero only when a non-dimensional spectrum exceeds the threshold at which waves are observed to start breaking. An additional source of short wave dissipation due to long wave breaking is introduced to represent the dissipation of short waves due to longer breaking waves. Several degrees of freedom are introduced in the wave breaking and the wind-wave generation term of Janssen (J. Phys. Oceanogr. 1991). These parameterizations are combined and calibrated with the Discrete Interaction Approximation of Hasselmann et al. (J. Phys. Oceangr. 1985) for the nonlinear interactions. Parameters are adjusted to reproduce observed shapes of directional wave spectra, and the variability of spectral moments with wind speed and wave height. The wave energy balance is verified in a wide range of conditions and scales, from gentle swells to major hurricanes, from the global ocean to coastal settings. Wave height, peak and mean periods, and spectral data are validated using in situ and remote sensing data. Some systematic defects are still present, but the parameterizations yield the best overall results to date. Perspectives for further improvement are also given.Comment: revised version for Journal of Physical Oceanograph

Harmonin-b, an actin-binding scaffold protein, is involved in the adaptation of mechanoelectrical transduction by sensory hair cells

We assessed the involvement of harmonin-b, a submembranous protein containing PDZ domains, in the mechanoelectrical transduction machinery of inner ear hair cells. Harmonin-b is located in the region of the upper insertion point of the tip link that joins adjacent stereocilia from different rows and that is believed to gate transducer channel(s) located in the region of the tip link's lower insertion point. In Ush1cdfcr-2J/dfcr-2J mutant mice defective for harmonin-b, step deflections of the hair bundle evoked transduction currents with altered speed and extent of adaptation. In utricular hair cells, hair bundle morphology and maximal transduction currents were similar to those observed in wild-type mice, but adaptation was faster and more complete. Cochlear outer hair cells displayed reduced maximal transduction currents, which may be the consequence of moderate structural anomalies of their hair bundles. Their adaptation was slower and displayed a variable extent. The latter was positively correlated with the magnitude of the maximal transduction current, but the cells that showed the largest currents could be either hyperadaptive or hypoadaptive. To interpret our observations, we used a theoretical description of mechanoelectrical transduction based on the gating spring theory and a motor model of adaptation. Simulations could account for the characteristics of transduction currents in wild-type and mutant hair cells, both vestibular and cochlear. They led us to conclude that harmonin-b operates as an intracellular link that limits adaptation and engages adaptation motors, a dual role consistent with the scaffolding property of the protein and its binding to both actin filaments and the tip link component cadherin-23

Enabling planetary science across light-years. Ariel Definition Study Report

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution

Trials

BACKGROUND: Postoperative upper gastrointestinal fistula (PUGIF) is a devastating complication, leading to high mortality (reaching up to 80%), increased length of hospital stay, reduced health-related quality of life and increased health costs. Nutritional support is a key component of therapy in such cases, which is related to the high prevalence of malnutrition. In the prophylactic setting, enteral nutrition (EN) is associated with a shorter hospital stay, a lower incidence of severe infectious complications, lower severity of complications and decreased cost compared to total parenteral nutrition (TPN) following major upper gastrointestinal (GI) surgery. There is little evidence available for the curative setting after fistula occurrence. We hypothesize that EN increases the 30-day fistula closure rate in PUGIF, allowing better health-related quality of life without increasing the morbidity or mortality. METHODS/DESIGN: The NUTRILEAK trial is a multicenter, randomized, parallel-group, open-label phase III trial to assess the efficacy of EN (the experimental group) compared with TPN (the control group) in patients with PUGIF. The primary objective of the study is to compare EN versus TPN in the treatment of PUGIF (after esophagogastric resection including bariatric surgery, duodenojejunal resection or pancreatic resection with digestive tract violation) in terms of the 30-day fistula closure rate. Secondary objectives are to evaluate the 6-month postrandomization fistula closure rate, time of first fistula closure (in days), the medical- and surgical treatment-related complication rate at 6 months after randomization, the fistula-related complication rate at 6 months after randomization, the type and severity of early (30 days after randomization) and late fistula-related complications (over 30 days after randomization), 30-day and 6-month postrandomization mortality rate, nutritional status at day 30, day 60, day 90 and day 180 postrandomization, the mean length of hospital stay, the patient's health-related quality of life (by self-assessment questionnaire), oral feeding time and direct costs of treatment. A total of 321 patients will be enrolled. DISCUSSION: The two nutritional supports are already used in daily practice, but most surgeons are reluctant to use the enteral route in case of PUGIF. This study will be the first randomized trial testing the role of EN versus TPN in PUGIF. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03742752. Registered on 14 November 2018.This research program is funded by the French Ministry of Health through Programme Hospitalier de Recherche Clinique 2016