S2O, polysulfuroxide and sulfur polymer on Io's surface?

To settle the question of disulfur monoxide and sulfur monoxide deposition and occurrence on Io's surface, we performed series of laboratory experiments reproducing the condensation of S₂O at low temperature. Its polymerization has been monitored by recording infrared spectra under conditions of temperature, pressure, mixing with SO₂ and UV-visible radiation simulating that of Io's surface. Our experiments show that S₂O condensates are not chemically stable under ionian conditions. We also demonstrate that SO and S₂O outgassed by Io's volcanoes and condensing on Io's surface should lead to yellow polysulfuroxide deposits or to white deposits of S₂O diluted in sulfur dioxide frost (i.e., S₂O/SO₂ < 0.1%). Thus S₂O condensation cannot be responsible for the red volcanic deposits on Io. Comparison of the laboratory infrared spectra of S₂O and polysulfuroxide with NIMS/Galileo infrared spectra of Io's surface leads us to discuss the possible identification of polysulfuroxide. We also recorded the visible transmission spectra of sulfur samples resulting from polysulfuroxide decomposition. These samples consist in a mixture of sulfur polymer and orthorhombic sulfur. Using the optical constants extracted from these measurements, we show that a linear combination of the reflectance spectra of our samples, the reflectance spectrum of orthorhombic S₈ sulfur and SO₂ reflectance spectrum, leads to a very good matching of Io's visible spectrum between 330 and 520 nm. We conclude then that Io's surface is probably mainly composed of sulfur dioxide and a mixture of sulfur S₈ and sulfur polymer. Some polysulfuroxide could also co-exist with these dominant components, but is probably restricted to some volcanic areas.     

Combining IR and X‐ray microtomography data sets: Application to Itokawa particles and to Paris meteorite

In the near future, a new generation of sample return missions (Hayabusa2, OSIRIS‐REx, MMX, etc.) will collect samples from small solar system bodies. To maximize the scientific outcome of laboratory studies and minimize the loss of precious extraterrestrial samples, an analytical sequence from less destructive to more destructive techniques needs to be established. In this work, we present a combined X‐ray and IR microtomography applied to five Itokawa particles and one fragment of the primitive carbonaceous chondrite Paris. We show that this analytical approach is able to provide a 3‐D physical and chemical characterization of individual extraterrestrial particles, using the measurement of their 3‐D structure and porosity, and the detection of mineral and organic phases, and their spatial co‐localization in 3‐D. We propose these techniques as an efficient first step in a multitechnique analytical sequence on microscopic samples collected by space missions.     

The efficiency of using a seismic base isolation system for a 2D concrete frame founded upon improved soft soil with rigid inclusions

2D finite element models were developed to analyze the effect of improved soft-soil foundation on the efficiency of a base-isolated concrete frame. Static and dynamic analyses were performed for a frame on raft foundation. Non-improved and improved soft-soil foundation using rigid inclusions were considered, as well as the use of high damping rubber bearing as base isolation. Results show that the use of rigid inclusions increases the efficiency of base isolation; base shear is reduced by 38% and maximum acceleration at the top of the frame by 30%.     

Detailed ground radiometric surveys on Gabal El Sela,Southeastern Desert,Egypt

Gabal El Sela area lies in the extreme southeastern part of the eastern desert in Egypt. It is covered by basement rocks of different compositions. The detailed work in this area covers about 4 km² and it is represented mainly by coarse younger granite as a curved shape extended in NE–SW direction and dissected by many faults in various trends; some of them are invaded by dykes especially the lamprophyre dykes in the ENE–WSW trend. Detailed geological, structural, and radiometric investigations are carried out on the area. The radiometric data are statistically analyzed and the results show that the total count radiometric map reflects six separate anomalies. The field work revealed that four anomalies are related to lamprophyre dykes, the other two anomalies are structurally controlled by NE–SW and E–W faults. These anomalies are followed by some trenches which traced and measured in detail exhibiting the possible extension of these anomalies with depth. These measurements show that lamprophyre dyke has the highest reading of radioactivity, it reaches 270 Ur in the surface and to 6,300 in the trenches. While the granite of the sela area is considered possesses high level of radioactivity, where its radioactivity ranges from 19.9 to 81 Ur with an average of about 32 Ur.     

Application of remotely sensed imagery to watershed analysis a case study of Lake Karoun, Egypt

Delineation of Lake Karoun watershed in Egypt was carried out and various watershed parameters and environmental characteristics were extracted using geographic information system and remote sensing. Environmental characteristics including normalized vegetation index (NDVI), moisture index, land surface temperature, and land use classes were obtained from high spatial resolution images (Landsat TM). Moreover, hydrological parameters, drainage flow directions, drainage networks, and catchments from digital elevation model have been delineated using the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) satellite images. As a result, the lake's watershed characteristics including the environmental and hydrological factors for each watershed zone were presented and analyzed. The information generated would be of immense help in hydrological modeling of watershed for prediction of runoff and sediment yield, thereby providing necessary inputs for developing suitable developmental management plans with sound scientific basis.     

Pore water transport of enterococci out of beach sediments

Enterococci are used to evaluate the safety of beach waters and studies have identified beach sands as a source of these bacteria. In order to study and quantify the release of microbes from beach sediments, flow column systems were built to evaluate flow of pore water out of beach sediments. Results show a peak in enterococci (average of 10% of the total microbes in core) released from the sand core within one pore water volume followed by a marked decline to below detection. These results indicate that few enterococci are easily removed and that factors other than simple pore water flow control the release of the majority of enterococci within beach sediments. A significantly larger quantity and release of enterococci were observed in cores collected after a significant rain event suggesting the influx of fresh water can alter the release pattern as compared to cores with no antecedent rainfall.