NaCl crystals grown by the evaporation of an aqueous salt solution in microgravity on the International Space Station (ISS) were characterized and compared to salt crystals grown on earth. NaCl crystallized as thin wafers in a supersaturated film of 200–700 μm thickness and 50 mm diameter, or as hopper cubes in 10 mm diameter supersaturated spheres. Neutron diffraction shows no change in crystal structure and in cell parameters compared to earth-grown crystals. However, the morphology can be different, frequently showing circular, disk-like shapes of single crystals with 〈1 1 1〉 perpendicular to the disks, an unusual morphology for salt crystals. In contrast to the growth on earth the lateral faces of the microgravity tabular hopper crystals are symmetrical because they are free floating during the crystallization process. Hopper cubes were produced without the need to suspend the growing crystals by an ongoing stirring. “Fleur de Sel” is shown as an example of two-dimensional growth of salt on earth and compared to the space grown crystals. It is shown that in microgravity conditions brine fluid inclusions form within the salt crystals.
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 degrees 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.
Leveraging electrokinetics for the active control of dendritic fullerene-1 release across a nanochannel membrane
General adoption of advanced treatment protocols such as chronotherapy will hinge on progress in drug delivery technologies that provide precise temporal control of therapeutic release. Such innovation is also crucial to future medicine approaches such as telemedicine. Here we present a nanofluidic membrane technology capable of achieving active and tunable control of molecular transport through nanofluidic channels. Control was achieved through application of an electric field between two platinum electrodes positioned on either surface of a 5.7 nm nanochannel membrane designed for zero-order drug delivery. Two electrode configurations were tested: laser-cut foils and electron beam deposited thin-films, configurations capable of operating at low voltage (=1.5 V), and power (100 nW). Temporal, reproducible tuning and interruption of dendritic fullerene 1 (DF-1) transport was demonstrated over multi-day release experiments. Conductance tests showed limiting currents in the low applied potential range, implying ionic concentration polarization (ICP) at the interface between the membrane's micro- and nanochannels, even in concentrated solutions (=1 M NaCl). The ability of this nanotechnology platform to facilitate controlled delivery of molecules and particles has broad applicability to next-generation therapeutics for numerous pathologies, including autoimmune diseases, circadian dysfunction, pain, and stress, among others.
The paper presents observation of relativistic electrons. Data are collected by the Radiation Risk Radiometer-Dosimeters (R3D) B2/B3 modifications during the flights of Foton M2/M3 satellites in 2005 and 2007 as well as by the R3DE instrument at the European Technology Exposure Facility (EuTEF) on the Columbus External Payload Adaptor at the International Space Station (ISS) in the per- iod February 20 – April 28, 2008. On the Foton M2/M3 satellites relativistic electrons are observed more frequently than on the ISS because of higher (62.8°) inclination of the orbit. At both Foton satellites the usual duration of the observations are a few minutes long. On the ISS the duration usually is about 1 min or less. The places of observations of high doses due to relativistic electrons are distributed mainly at latitudes above 50° geographic latitude in both hemispheres on Foton M2/M3 satellites. A very high maximum is found in the southern hemisphere at longitudinal range 0°–60°E. At the ISS the maximums are observed between 45° and 52° geographic latitude in both hemispheres mainly at longitudes equatorward from the magnetic poles. The measured absolute maximums of dose rates generated by relativistic electrons are found to be as follows: 304 lGy h 1 behind 1.75 g cm 2 shielding at Foton M2, 2314 lGy h 1 behind 0.71 g cm 2 shielding at Foton M3 and 19,195 lGy h 1 (Flux is 8363 cm 2 s 1) behind les than 0.4 g cm 2 shielding at ISS.
The Human Genome Project changed everything—or did it? Although un-deniably a scientific tour de force, the Genome Project’s outcome posed more questions than it answered, and molecular biology has been working assiduously ever since to answer those questions.
The microgravity DSC-DCMIX1 mission onboard ISS: Experiment description and results on the measurement of the Soret coefficients for isobutylbenzene, dodecane, tetralin ternary hydrocarbons mixtures
In the energy sector, in particular for hydrocarbon reservoirs, accurate simulation of the various forms of mass flux is important in oil exploration and optimal oil recovery. Since the diffusion and thermodiffusion coefficients of binary hydrocarbon mixtures have been measured and analyzed in detail elsewhere (Urteaga et al., 2012; Jaber et al., 2009; Kianian et al., 2012), here we experimentally analyzed and reported the separation in a ternary hydrocarbon mixture of tetrahydronaphthalene, isobutylbenzene, and dodecane due to thermal gradients, and we determined the Soret coefficients of this mixture for four different compositions. The thermodiffusion experiment was conducted by means of a Mach–Zehnder Interferometer (MZI) using two wavelengths and in a low gravity environment on board the International Space Station (ISS). Thus, we report the chemical concentration variations of the various cases obtained by the recently developed processing technique. In addition we investigated the reliability and the repeatability of the MZI experiment to study thermodiffusion for ternary mixtures. Finally, according to the transient behavior of the separation of the components, the Soret diffusion coefficients for various compositions of this mixture were measured and then compared.
We present a transient experimental analysis of the DCMIX1 project conducted onboard the International Space Station for a ternary tetrahydronaphtalene, isobutylbenzene, n-dodecane mixture. Raw images taken in microgravity environment using the SODI (Selectable Optical Diagnostic) apparatus which is equipped with two wavelength diagnostic were processed and the results were analyzed in this work. We measured the concentration profile of the mixture containing 80% THN, 10% IBB and 10% nC12 during the entire experiment using an advanced image processing technique and accordingly we determined the Soret coefficients using an advanced curve-fitting and post-processing technique. It must be noted that the experiment has been repeated five times to ensure the repeatability of the experiment.
Effect of Varying the Initial Diameter of n-Octane and n-Decane Droplets over a Wide Range on the Spherically Symmetric Combustion Process: International Space Station and Ground-based Experiments
This study reports on an investigation of varying the initial droplet diameter (Do) over a very wide range (from 0.5 mm to 5 mm) on droplet combustion. The droplet burning history is examined in an environment of reduced convection as promoted by low gravity to achieve spherical droplet flames. The fuels examined are n-octane and n-decane. The long burning times for Do > 1.2 mm were accommodated in the Multi-user Droplet Combustion Apparatus (MDCA) onboard the orbiting International Space Station (ISS), while experiments for Do < 1 mm were carried out in a ground-based drop tower. The results reported encompass the widest range of Do examined in the history of droplet combustion experimentation for a given fuel. Both free floating (unsupported) and fiber-supported droplets are deployed and ignited. Quantitative data are obtained from digital analysis of the individual video images of the burning process for the droplet, flame and soot shell diameters. Results show that the droplet burning rate decreases with increasing Do throughout the Do range investigated. The mechanisms responsible include a combination of fuel molecule residence time effects and radiative losses from the flame, both of which influence soot formation to varying degrees. Assuming that increasing soot formation (e.g., from increasing residence times) would lower heat transfer to the droplet, "small" droplets (Do < 1 mm, with negligible radiation losses) will burn slower as Do increases in this initial droplet diameter range, which is consistent with the experimental results. For Do > 1.5 mm the droplet flames appeared less luminous and therefore less sooty, yet the droplets continued to burn progressively slower as Do increased. This effect is conjectured to be the result of increased radiative losses that would tend to reduce sooting that outweigh the longer residence times of the larger droplets that would tend to increase sooting. The experimental results reported also include the evolution of relative distances between the flame, soot shell, and droplet diameters, all of which are influenced by Do.
EFFECT OF THERMAL DRIFT ON THE INITIAL TRANSIENT BEHAVIOR IN DIRECTIONAL SOLIDIFICATION OF A BULK TRANSPARENT MODEL ALLOY
In situ monitoring of directional solidification experiments on a transparent model alloy was carried out under low gravity in the Directional Solidification Insert of the Device for the Study of Critical Liquids and Crystallization (DECLIC-DSI) on-board the International Space Station. The present work is focused on the analysis of the interface recoil and its macroscopic shape evolution. Theoretically the interface movement is due to the formation of a solute boundary layer in front of the interface. However, the bulk configuration and the thermal specificities of transparent systems induce thermal effects, which are usually not observed in the classical thin sample configuration. Numerical thermal modeling highlights two thermal contributions to the interface recoil, both increasing with pulling rate. The Warren and Langer model is modified to take into account these contributions that modify the interface dynamics, and a good agreement is obtained between the experiments and the modified model.
Assessment of polycarbonate filter in a molecular analytical system for the microbiological quality monitoring of recycled waters onboard ISS
On the ISS, as on Earth, water is an essential element for life and its quality control on a regular basis allows to ensure the health of the crew and the integrity of equipment. Currently, microbial water analysis onboard ISS still relies on the traditional culture-based microbiology methods. Molecular methods based on the amplification of nucleic acids for microbiological analysis of water quality show enormous potential and are considered as the best alternative to culture-based methods. For this reason, the Midass, a fully integrated and automated prototype was designed conjointly by ESA and bioMerieux for a rapid monitoring of the microbiological quality of air. The prototype allows air sampling, sample processing and the amplification/detection of nucleic acids. We describe herein the proof of principle of an analytical approach based on molecular biology that could fulfill the ESA’s need for a rapid monitoring of the microbiological quality of recycled water onboard ISS. Both concentration and recovery of microorganisms are the main critical steps when the microfiltration technology is used for water analysis. Among filters recommended standards for monitoring the microbiological quality of the water, the polycarbonate filter was fully in line with the requirements of the ISO 7704-1985 standard in terms of efficacy of capture and recovery of bacteria. Moreover, this filter does not retain nucleic acids on the surface and has no inhibitory effect on their downstream processing steps such as purification and amplification/detection. Although the Midass system was designed for the treatment of air samples, the first results on the integration of PC filters were encouraging. Nevertheless, system modifications are needed to better adapt the Midass system for the monitoring of the microbiological water quality.