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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.11.011 Byline: B. Diez (a), W.C. Feldman (b), N. Mangold (c)(e), D. Baratoux (d), S. Maurice (a), O. Gasnault (a), L. d'Uston (a), F. Costard (c) Keywords: Mars; surface; Gamma ray spectroscopy; Data reduction techniques; Regoliths Abstract: The neutron signals measured by the Neutron Spectrometer on board the Mars Odyssey satellite are analyzed at Central Elysium Planitia. The neutron currents have variations associated with the boundaries of geological units in all three energy ranges: thermal, epithermal and fast neutron. Geochemical constraints can be derived from the neutron data using macroscopic absorption cross sections. This variable measures the ability of a material to absorb neutrons, giving clues of its chemical composition. The neutron derived chemical constraints are compared with the elemental abundances measured by the Gamma Subsystem, also on board Mars Odyssey. Differences between the two datasets are interpreted to reflect heterogeneities of probed surfaces. The knowledge already derived from other observations and a detailed examination of the GRS datasets are used to determine a general overview of the geology of the region and possible mechanisms of emplacement. The particular role played by chlorine in this scheme is emphasized. Author Affiliation: (a) CESR, Universite Paul Sabatier, CNRS, 9 Avenue Colonel Roche, B.P. 44346, 31028 Toulouse Cedex 4, France (b) Planetary Science Institute, 1700 E. Fort Lowell Rd. #106, Tucson, AZ 85719, USA (c) IDES, Universite Paris Sud, CNRS, Orsay, France (d) LDTP, Observatoire Midi-Pyrenees, Universite Paul Sabatier, CNRS, Toulouse, France (e) LPGN, Universite Nantes/CNRS, France Article History: Received 30 May 2008; Revised 9 September 2008; Accepted 3 November 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.02.006 Byline: B. Diez (a), W.C. Feldman (b), S. Maurice (a), O. Gasnault (a), T.H. Prettyman (c), M.T. Mellon (d), O. Aharonson (e), N. Schorghofer (f) Keywords: Mars; polar caps; Ices; Mineralogy; Gamma ray spectroscopy; Data reduction techniques Abstract: We explore the capability of a method of mapping the depth distribution of a hydrogen-rich layer in the top meter of Mars from the neutron currents measured by the Mars Odyssey Neutron Spectrometer. Assuming the soil can be modeled by two layers of known composition having different hydrogen contents, simulations allow an inversion of the neutron data into knowledge of depth and hydrogen content of the lower layer. The determination of these variables is sensitive to the hypothesis of chemical composition of the soil. We quantify this contribution to the uncertainty in the method first in terms of individual chemical elements and then in terms of macroscopic absorption cross sections. To minimize this source of error, an average composition was inferred from Mars Exploration Rover data. Possible compositions having a wide range of macroscopic absorption cross sections were used to evaluate the uncertainty associated with our calculations. We finally compare our results to ice table depth estimates predicted by two published theoretical models at locations where the composition is relatively well known. The fit is excellent in the southern high latitudes but questionable in the northern high latitudes. Possible explanations of these differences include the high geographical variations of the neutron currents relative to the spatial width of the response function of the instrument and the overly simple model we, of necessity, used for surface layering. Author Affiliation: (a) Universite Paul Sabatier, Centre d'Etude Spatiale des Rayonnements, 9 avenue Colonel Roche, B.P. 44346, 31028 Toulouse cedex 4, France (b) Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719, USA (c) Los Alamos National Laboratory, Group ISR-1, PO Box 1664, MSB241, Los Alamos, NM 87545, USA (d) Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovative Drive, Boulder, CO 80303-7814, USA (e) Division of Geological and Planetary Sciences, Californian Institute of Technology, MC170-25 1200 E. California Blvd., Pasadena, CA 91125, USA (f) Institute for Astronomy, University of Hawaii at Manoa, 2680 Woodlawn Drive, Honolulu, HI 96822-1897, USA Article History: Received 15 June 2007; Revised 7 February 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2007.08.044 Byline: W.C. Feldman (a), M.C. Bourke (a)(b), R.C. Elphic (c), S. Maurice (d), J. Bandfield (e), T.H. Prettyman (c), B. Diez (d), D.J. Lawrence (c) Keywords: Mars; polar geology; Mars; polar caps; Ices Abstract: Neutron currents measured using the Mars Odyssey Neutron Spectrometer, seasonally varying temperatures measured using the Thermal Emission Spectrometer, and visible images measured using the High Resolution Imaging Science Experiment (HiRISE) are studied to determine the water content and stratigraphy of Olympia Undae. Both the neutron and thermal infrared data are best represented by a two-layered model having a water-ice equivalent hydrogen content of 30[+ or -]5% in a lower semi-infinite layer, buried beneath a relatively desiccated upper layer that is 9[+ or -]6 g/cm.sup.2 thick (about 6 cm depth at a density of 1.5 g/cm.sup.3). A model that is consistent with all three data sets is that the dunes contain a top layer that is relatively mobile, which overlays a niveo-aeolian lower layer. The geomorphology shown by the HiRISE images suggests that the bottom layer may be cemented in place and therefore relatively immobile. Author Affiliation: (a) Planetary Science Institute, 1700 E. Fort Lowell, Suite 106, Tucson, AZ 85719, USA (b) Oxford University Centre for the Environment, University of Oxford, Oxford, OX13QY, UK (c) Los Alamos National Laboratory, Mail Stop D466, Los Alamos, NM 87545, USA (d) Centre d'Etude Spatiale des Rayonnements, 9 av. Colonel Roche, 31500, Toulouse, France (e) Arizona State University, School of Earth and Space Exploration, Tempe, AZ 85287-6305, USA Article History: Received 13 April 2007; Revised 20 July 2007

Graphical abstract Highlights • MZPPY composite was explored for Cr(VI) removal from water in fixed-bed column. • Lower AER values indicated good performance removal of Cr(VI) ions. • Yoon–Nelson and Thomas models described well the breakthrough curves. Abstract A composite of magnetized natural zeolite and polypyrrole (MZ-PPY) was synthesized and used to explore Cr(VI) removal from aqueous solution and environmental water. A column dynamic set up was employed to analyse adsorption breakthrough performance under different process conditions. Material characterization was done to assess morphology and functional groups and to elucidate Cr(VI) removal mechanism. Results indicate that Cr(VI) removal is a function of bed mass, flowrate and initial Cr(VI) concentration. Sharp breakthrough curves were obtained which are fingerprints of reaction kinetics controlled adsorption process. Consequently, three simple kinetic models; Yoon–Nelson, Thomas and Bohart–Adams were applied to the experimental data to predict the breakthrough curves and to determine the characteristic parameters of the column that are useful for process design. The Yoon–Nelson and Thomas models were found to appropriately describe the breakthrough curves. From material characterization, Cr(VI) removal proceeded mainly by adsorption and reduction. Meanwhile using adsorbent exhaustion rate (AER) as performance indicator, a low value of 0.25 was obtained for environmental water from a chrome mine suggesting that MZ-PPY is a highly efficient adsorption media. [ABSTRACT FROM AUTHOR]

In this study, eggshell (ES) powder was evaluated as a cheap and biocompatible waste material for the pre-treatment of acid mine drainage (AMD) leachate from coal dump. First, the composition of the AMD and physiochemical properties of the ES powder were determined using various standard characterization techniques. Then the removal efficiency of the target metal contaminants and the acid-neutralisation effect were explored in batch and kinetic set-ups. Thereafter, the settling rate of sludge formed after separately reacting ES and limestone powders with AMD was explored. Results revealed that the AMD leachate was highly acidic and contaminated with both cations and anions. Thermogravimetric analysis (TGA) and X-ray fluorescence (XRF) analyses demonstrated that ES powder was thermally stable up to 700 °C and CaO was the main component, respectively. Scanning electron microscopy (SEM) and EDX spectra confirmed the removal of contaminants. Both the decrease in particle size and increase in mass of ES enhanced the treatment efficiency. Although complete Fe and Al removal was achieved, Mn and sulphates posed a challenge as they were partially removed. Meanwhile, ES demonstrated superior acid-neutralizing effect to limestone and the mine water clarity and pH were shifted to acceptable levels. Both Fe and Al removal proceeded through an exothermic process while it was opposite for Mn. Kinetics were rapid and the sludge from ES powder settled faster compared with that from limestone powder. Cost analysis indicated that significant financial savings can be realised by substituting limestone with ES material. The findings suggest that ES waste could be an efficient and cheap material in the pre-treatment of AMD effluents. [ABSTRACT FROM AUTHOR]

The present study evaluated the treatment of municipal wastewater containing phenol using solar and ultraviolet (UV) light photocatalytic ozonation processes to explore comparative performance. Important aspects such as catalyst reuse, mineralization of pollutants, energy requirements, and toxicity of treated wastewater which are crucial for practical implementation of the processes were explored. The activity of the photocatalysts did not change significantly even after three consecutive uses despite approximately 2% of the initial quantity of catalyst being lost in each run. Analysis of the change in average oxidation state (AOS) demonstrated the formation of more oxidized degradation products (ΔAOS values of 1.0–1.7) due to mineralization. The energy requirements were determined in terms of electrical energy per order (E EO ) and the collector area per order (A CO ). The E EO (kWh m −3 Order −1 ) values were 26.2 for ozonation, 38–47 for UV photocatalysis and 7–22 for UV photocatalytic ozonation processes. On the other hand, A CO (m 2 m −3 order −1 ) values were 31–69 for solar photocatalysis and 8–13 for solar photocatalytic ozonation. Thus photocatalytic ozonation processes required less energy input compared to the individual processes. The cytotoxicity of the wastewater was analysed using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay with Vero cells. The cell viability increased from 28.7% in untreated wastewater to 80% in treated wastewater; thus showing that the treated wastewater was less toxic. The effectiveness of photocatalytic ozonation, recovery and reusability of the photocatalysts, as well as detoxification of the wastewater make this low energy consumption process attractive for wastewater remediation. [ABSTRACT FROM AUTHOR]

Summary Myotonic dystrophy types 1 (DM1) and 2 (DM2) are dominantly inherited neuromuscular disorders caused by a toxic gain of function of expanded CUG and CCUG repeats, respectively. Although both disorders are clinically similar, congenital myotonic dystrophy (CDM), a severe DM form, is found only in DM1. CDM is also characterized by muscle fiber immaturity not observed in adult DM, suggesting specific pathological mechanisms. Here, we revealed upregulation of the interleukin-6 (IL-6) myokine signaling pathway in CDM muscles. We also found a correlation between muscle immaturity and not only IL-6 expression but also expanded CTG repeat length and CpG methylation status upstream of the repeats. Aberrant CpG methylation was associated with transcriptional dysregulation at the repeat locus, increasing the toxic RNA burden that upregulates IL-6. Because the IL-6 pathway is involved in myocyte maturation and muscle atrophy, our results indicate that enhanced RNA toxicity contributes to severe CDM phenotypes through aberrant IL-6 signaling. [ABSTRACT FROM AUTHOR]

Summary Brain function is compromised in myotonic dystrophy type 1 (DM1), but the underlying mechanisms are not fully understood. To gain insight into the cellular and molecular pathways primarily affected, we studied a mouse model of DM1 and brains of adult patients. We found pronounced RNA toxicity in the Bergmann glia of the cerebellum, in association with abnormal Purkinje cell firing and fine motor incoordination in DM1 mice. A global proteomics approach revealed downregulation of the GLT1 glutamate transporter in DM1 mice and human patients, which we found to be the result of MBNL1 inactivation. GLT1 downregulation in DM1 astrocytes increases glutamate neurotoxicity and is detrimental to neurons. Finally, we demonstrated that the upregulation of GLT1 corrected Purkinje cell firing and motor incoordination in DM1 mice. Our findings show that glial defects are critical in DM1 brain pathophysiology and open promising therapeutic perspectives through the modulation of glutamate levels. [ABSTRACT FROM AUTHOR]

Transformation of agricultural waste such as banana peels into a valuable sorbent material has been proven effective and efficient in wastewater treatment. Further, transformation into nanosorbent to enhance the removal capacity of actinides (uranium and thorium) from synthetic and real mine water is extensively investigated in this study. The nanosorbent samples before and after adsorption were characterised by X-ray diffraction (XRD), Fourier transform infra-red (FTIR), zetasizer nanoseries and scanning electron microscopy (SEM) while the amount of radioactive substances adsorbed was determined by inductively coupled plasma optical emission spectroscopy. Results revealed that there was a crystallite size and particle size reduction from 108 to 12 nm and <65,000 nm to <25 nm respectively as a function of milling time. Furthermore, appearance and disappearance of nanofibers via milling was noticed during structural analysis. The functional groups responsible for the banana peels capability to coordinate and remove metal ions were identified at absorption bands of 1730 cm −1 (carboxylic groups) and 889 cm −1 (amine groups) via FTIR analysis. Equilibrium isotherm results demonstrated that the adsorption process was endothermic for both uranium and thorium. The Langmuir maximum adsorption capacity was 27.1 mg g −1 , 34.13 mg g −1 for uranium and 45.5 mg g −1 , 10.10 mg g −1 for thorium in synthetic and real mine water, respectively. The results obtained indicate that nanostructured banana peels is a potential adsorbent for the removal of radioactive substances from aqueous solution and also from real mine water. However, the choice of this sorbent material for any application depends on the composition of the effluent to be treated. [ABSTRACT FROM AUTHOR]