European Space Agency experiments on thermodiffusion of fluid mixtures in space.

This paper describes the European Space Agency (ESA) experiments devoted to study thermodiffusion of fluid mixtures in microgravity environment, where sedimentation and convection do not affect the mass flow induced by the Soret effect. First, the experiments performed on binary mixtures in the IVIDIL and GRADFLEX experiments are described. Then, further experiments on ternary mixtures and complex fluids performed in DCMIX and planned to be performed in the context of the NEUF-DIX project are presented. Finally, multi-component mixtures studied in the SCCO project are detailed.

Development of a high-pressure set-up for measurements of binary diffusion coefficients in supercritical carbon dioxide.

We present the development of a high-pressure apparatus for measurements of diffusion coefficients in supercritical fluids. The Taylor dispersion method has been adapted to conduct experiments at the pressures up to 25.0 MPa. In order to test the developed set-up, binary diffusion coefficients D at infinite dilution in supercritical carbon dioxide have been measured for a reference system, benzene, at temperatures in the range of 309.50-319.95 K. The effects of flow velocity, number of consecutive injections and absorbance at different wave numbers on the diffusion coefficient have been analysed. The obtained diffusion coefficients are of the order of 10-8 m 2/s and in excellent agreement with the available literature data.

Fickian Diffusion in Ternary Mixtures Composed by 1,2,3,4-Tetrahydronaphthalene, Isobutylbenzene, and n-Dodecane.

We report the Fickian diffusion coefficients in 20 ternary mixtures formed by 1,2,3,4-tetrahydronaphthalene (THN), isobutylbenzene (IBB) and n-dodecane (nC12) measured by the Taylor dispersion technique at 298.1 K and atmospheric pressure. Four diffusion coefficients of the ternary mixtures were measured along six concentration paths starting on one binary subsystem and moving toward the other one. We found expressions for the diffusion matrix of a ternary mixture approaching to the binary limits. The measured diffusion coefficients were thoroughly verified by comparison with the theoretical asymptotic behavior. The main diffusion coefficients vary smoothly over the entire concentration space and D11 is always larger than D22. One of the two cross-diffusion coefficients is of the same order of magnitude as the main ones and, hence, not negligible, whereas the other one is close to zero. The investigated mixtures also comprise compositions that were examined in microgravity experiments in the ESA DCMIX1 project.

Investigation of Fickian diffusion in the ternary mixtures of water-ethanol-triethylene glycol and its binary pairs.

We present a comprehensive experimental study of isothermal Fickian diffusion in the ternary and binary liquid mixtures of water, ethanol, and triethylene glycol over the entire ternary composition space. 21 ternary mixtures inside the composition triangle have been investigated by means of the Taylor dispersion technique and 30 binary mixtures by Taylor dispersion and/or optical beam deflection in a Soret cell. The scalar binary diffusion coefficient has been determined along all three binary boundaries of the composition space and compared with estimations based on the Stokes-Einstein relation using stick or slip boundary conditions. The four elements of the ternary diffusion matrix and the diffusion eigenvalues were determined over a large portion of the composition triangle. The pseudo-binary diffusion coefficients obtained in Taylor dispersion experiments with either one of the two independent concentrations kept constant are comparable to the two diffusion eigenvalues. One of the two off-diagonal elements of the diffusion matrix is of the same order as the diagonal ones and, hence, not negligible, whereas the other one is approximately one order of magnitude smaller. Where available, our results compare well with literature data. The investigated compositions also comprise the five compositions that are scheduled for microgravity experiments in the ESA DCMIX3 project.

Contribution to the benchmark for ternary mixtures: Measurement of the Soret, diffusion and thermodiffusion coefficients in the ternary mixture THN/IBB/nC12 with 0.8/0.1/0.1 mass fractions in ground and orbital laboratories.

We have determined the Soret (ST), diffusion (D, and thermodiffusion (DT) coefficients in a ternary mixture of tetralin-isobutylbenzene-n-dodecane with a composition of 0.80/0.10/0.10 by mass fraction at a temperature of 298K. The Soret coefficients were measured in the microgravity experiment DCMIX1 and on the ground by optical digital interferometry (ODI) using two lasers with different wavelengths. The values of the Soret coefficients were determined from the stationary separation of the components using two- and six-parameter fits. The diffusion coefficients were independently measured using the Taylor Dispersion Technique in the ground laboratory, and the thermodiffusion coefficients were derived from known ST and matrix D. The processing of the data from the DCMIX experiment conducted on the International Space Station is discussed in detail. The multi-user design of the on-board instrument causes perturbations in the component separation. Several recommendations are suggested for improving the quality of the microgravity results. For example, we demonstrated that the tomography reconstruction of the 3-D concentration field allows to restore the underestimated component separation resulting from the spatial non-linearity of the temperature field. Furthermore, to avoid errors in component separation due to mass exchange between the working liquid volume and the expansion volume at the top of the cell, we suggest considering the evolution of the separation only in the lower half of the cell. The results of this study displayed reasonable quantitative agreement between the microgravity and ground experiments.

Benchmark values for the Soret, thermodiffusion and molecular diffusion coefficients of the ternary mixture tetralin+isobutylbenzene+n-dodecane with 0.8-0.1-0.1 mass fraction.

With the aim of providing reliable benchmark values, we have measured the Soret, thermodiffusion and molecular diffusion coefficients for the ternary mixture formed by 1,2,3,4-tetrahydronaphthalene, isobutylbenzene and n-dodecane for a mass fraction of 0.8-0.1-0.1 and at a temperature of 25°C. The experimental techniques used by the six participating laboratories are Optical Digital Interferometry, Taylor Dispersion technique, Open Ended Capillary, Optical Beam Deflection, Thermogravitational technique and Sliding Symmetric Tubes technique in ground conditions and Selectable Optical Diagnostic Instrument (SODI) in microgravity conditions. The measurements obtained in the SODI installation have been analyzed independently by four laboratories. Benchmark values are proposed for the thermodiffusion and Soret coefficients and for the eigenvalues of the diffusion matrix in ground conditions, and for Soret coefficients in microgravity conditions.

Additional intranasal oxytocin to escitalopram improves depressive symptoms in resistant depression: an open trial.

The aim of this open trial was to assess the antidepressant/anxiolytic effects of oxytocin used as an adjunct to antidepressant in treatment-resistant depression. Fourteen patients, who have not responded to 40mg of escitalopram, received intranasal synthetic oxytocin during 4 weeks, in association with antidepressant. This is the first open trial study suggesting OT in association with escitalopram significantly reduced scores on Hamilton Depression Rating Scale.

Soret separation in a binary liquid mixture near its critical temperature.

The values of transport coefficients near a critical point are typically enhanced compared to the values in the classical region far away from a critical point. We report on the impact of the asymptotic behavior of the mass diffusion near the critical region on the Soret separation of the components in a model binary mixture. Concentration patterns are numerically investigated in the case of a spatially varying temperature. The Soret separation in ordinary mixture leads to the establishing of a linear concentration distribution in a steady state. The presence of the critical point redistributes the concentration field, it creates a thin layer with sharp concentration change at the critical region which can be seen as a horizontal plateau on vertical profiles. Large concentration gradients are established across this layer. The analysis showed that the kinetic of the separation significantly depends on whether the critical temperature is inside or outside of the applied temperature region, which is T(cold) ≤ T ≤ T(hot). Critical separation road is suggested for the case when T(cr) is located inside this region, T(cold) ≤ T(cr) ≤ T(hot).

Investigation of Fickian diffusion in the ternary mixture of 1,2,3,4-tetrahydronaphthalene, isobutylbenzene, and dodecane.

We present a comprehensive analysis of experimental results obtained for Fickian diffusion in the benchmark ternary liquid mixture of 1,2,3,4-tetrahydronaphthalene, isobutylbenzene, and dodecane (nC12) with equal mass fractions. Isothermal diffusion coefficients have been measured by two independent experimental methods: by Taylor dispersion technique, and by a counter flow cell fitted with an optical interferometry device. The experimental diffusion matrices have been critically analyzed regarding the Onsager reciprocal relations, for which we introduce a matrix asymmetry index s(2) that is independent of the frame of reference and the component order.

A new device to mimic intermittent hypoxia in mice.

Intermittent hypoxia (hypoxia-reoxygenation) is often associated with cardiovascular morbidity and mortality. We describe a new device which can be used to submit cohorts of mice to controlled and standardised hypoxia-normoxia cycles at an individual level. Mice were placed in individual compartments to which similar gas flow parameters were provided using an open loop strategy. Evaluations made using computational fluid dynamics were confirmed by studying changes in haemoglobin oxygen saturation in vivo. We also modified the parameters of the system and demonstrated its ability to generate different severities of cyclic hypoxemia very precisely, even with very high frequency cycles of hypoxia-reoxygenation. The importance of the parameters on reoxygenation was shown. This device will allow investigators to assess the effects of hypoxia-reoxygenation on different pathological conditions, such as obstructive sleep apnoea or chronic obstructive pulmonary disease.

Ascending aortic aneurysm in a patient with mixed gonadal dysgenesis.

Cardiovascular and endocrine complications in male or sexually-ambiguous patients carrying a 45,X/46,XY mosaicism are rarely discussed in the medical literature. However, young female patients with a diagnosis of Turner's disease usually benefit from regular cardiologic and endocrine follow-up, in accordance with current international guidelines. We report the case of a male patient, aged 23 years, with an ambiguous phenotype known to harbor a mixed gonadic 45,X/46,XY type dysgenesis. The patient was admitted to the cardiology ward for investigation and management of cardiac failure secondary to both a biscupid aortic valve and ascending aorta aneurysm. This case report, and the few others, which have been previously reported in the literature, emphasizes the importance of cardiologic and endocrine follow-up in male carriers of 45,X/46,XY mosaicism.

Oxytocin: From milk ejection to maladaptation in stress response and psychiatric disorders. A psychoneuroendocrine perspective.

Oxytocin (OT) is implicated in stress reduction as well as in social behavior. It inhibits the stress-induced activity of the hypothalamic-pituitary adrenal axis responsiveness. OT is involved in social affiliation, sexual and maternal-infant binding, anxiety, mood, feeding control and memory. Several lines of evidence suggest a role of OT in psychiatric disorders. Various psychiatric disorders are strongly influenced by social variables, such as panic attacks, depression and early childhood autism, and seem to exhibit a particularly close connection with the brain dynamics that underlie social emotions. This paper proposes an overview of OT in psychiatric disorders through the links with the stress response and prosocial behavior.

[Severe hyponatremia revealing Sheehan's syndrome]. / Une hyponatrémie sévère révélatrice d'un syndrome de Sheehan.

We describe the case of a young woman admitted for severe hyponatremia due to hypopituitarism caused by a Sheehan's syndrome. Sheehan's syndrome is a rare disorder. It develops after obstetrical hemorrhage that causes ischemic necrosis of the pituitary gland. In most cases, illness appears progressively and diagnosis is made after variable delay. Acute syndrome may develop immediately after delivery in some rare cases. Hyponatremia is a frequent manifestation and may be severe. It is principally caused by secondary adrenal failure.

ISA, ISSAM, EAU, EAA and ASA recommendations: investigation, treatment and monitoring of late-onset hypogonadism in males.

The new ISA, ISSAM, EAU, EAA and ASA recommendations on the investigation, treatment and monitoring of late-onset hypogonadism in males provide updated evidence-based information for clinicians who diagnose and treat patients with adult onset, age related testosterone deficiency.

[Secondary amenorrhea and cerebral ventriculomegaly]. / Aménorrhée secondaire et ventriculomégalie cérébrale.

Cerebral ventriculomegaly and hydrocephalus are not frequently associated with endocrine disorders of the gonadotropic axis. The mechanism of this association is not clarified. The most probable cause is however a partial hypothalamic dysfunction. The examination of the few reported cases is in favour of this explanation. We present the case of a young woman with a cerebral ventriculomegaly and suffering from secondary amenorrhea. Shunt was not necessary from the neurological point of view, the problem of secondary amenorrhea and anovulatory infertility was solved by clomiphen citrate therapy.

Impact of conditions at start-up on thermovibrational convective flow.

The development of thermovibrational convection in a cubic cell filled with high Prandtl number liquid (isopropanol) is studied. Direct nonlinear simulations are performed by solving three-dimensional Navier-Stokes equations in the Boussinesq approximation. The cell is subjected to high frequency periodic oscillations perpendicular to the applied temperature gradient under zero gravity. Two types of vibrations are imposed: either as a sine or cosine function of time. It is shown that the initial vibrational phase plays a significant role in the transient behavior of thermovibrational convective flow. Such knowledge is important to interpret correctly short-duration experimental results performed in microgravity, among which the most accessible are drop towers ( approximately 5s) and parabolic flights ( approximately 20s) . It is obtained that under sine vibrations, the flow reaches steady state within less than one thermal time. Under cosine acceleration, this time is 2 times longer. For cosine excitations, the Nusselt number is approximately 10 times smaller in comparison with the sine case. Besides, in the case of cosine, the Nusselt number oscillates with double frequency. However, at the steady state, time-averaged and oscillatory characteristics of the flow are independent of the vibrational start-up. The only feature that always differs the two cases is the phase difference between the velocity, temperature, and accelerations. We have found that due to nonlinear response of the system to the imposed vibrations, the phase shift between velocity and temperature is never equal exactly to pi2 , at least in weightlessness. Thus, heat transport always exists from the beginning of vibrations, although it might be weak.