Brine-driven destruction of clay minerals in Gale crater, Mars.

Mars' sedimentary rock record preserves information on geological (and potential astrobiological) processes that occurred on the planet billions of years ago. The Curiosity rover is exploring the lower reaches of Mount Sharp, in Gale crater on Mars. A traverse from Vera Rubin ridge to Glen Torridon has allowed Curiosity to examine a lateral transect of rock strata laid down in a martian lake ~3.5 billion years ago. We report spatial differences in the mineralogy of time-equivalent sedimentary rocks <400 meters apart. These differences indicate localized infiltration of silica-poor brines, generated during deposition of overlying magnesium sulfate-bearing strata. We propose that destabilization of silicate minerals driven by silica-poor brines (rarely observed on Earth) was widespread on ancient Mars, because sulfate deposits are globally distributed.

Spectral, Compositional, and Physical Properties of the Upper Murray Formation and Vera Rubin Ridge, Gale Crater, Mars.

During 2018 and 2019, the Mars Science Laboratory Curiosity rover investigated the chemistry, morphology, and stratigraphy of Vera Rubin ridge (VRR). Using orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars, scientists attributed the strong 860 nm signal associated with VRR to the presence of red crystalline hematite. However, Mastcam multispectral data and CheMin X-ray diffraction (XRD) measurements show that the depth of the 860 nm absorption is negatively correlated with the abundance of red crystalline hematite, suggesting that other mineralogical or physical parameters are also controlling the 860 nm absorption. Here, we examine Mastcam and ChemCam passive reflectance spectra from VRR and other locations to link the depth, position, and presence or absence of iron-related mineralogic absorption features to the XRD-derived rock mineralogy. Correlating CheMin mineralogy to spectral parameters showed that the ~860 nm absorption has a strong positive correlation with the abundance of ferric phyllosilicates. New laboratory reflectance measurements of powdered mineral mixtures can reproduce trends found in Gale crater. We hypothesize that variations in the 860 nm absorption feature in Mastcam and ChemCam observations of VRR materials are a result of three factors: (1) variations in ferric phyllosilicate abundance due to its ~800-1,000 nm absorption; (2) variations in clinopyroxene abundance because of its band maximum at ~860 nm; and (3) the presence of red crystalline hematite because of its absorption centered at 860 nm. We also show that relatively small changes in Ca-sulfate abundance is one potential cause of the erosional resistance and geomorphic expression of VRR.

Evidence for Multiple Diagenetic Episodes in Ancient Fluvial-Lacustrine Sedimentary Rocks in Gale Crater, Mars.

The Curiosity rover's exploration of rocks and soils in Gale crater has provided diverse geochemical and mineralogical data sets, underscoring the complex geological history of the region. We report the crystalline, clay mineral, and amorphous phase distributions of four Gale crater rocks from an 80-m stratigraphic interval. The mineralogy of the four samples is strongly influenced by aqueous alteration processes, including variations in water chemistries, redox, pH, and temperature. Localized hydrothermal events are evidenced by gray hematite and maturation of amorphous SiO2 to opal-CT. Low-temperature diagenetic events are associated with fluctuating lake levels, evaporative events, and groundwater infiltration. Among all mudstones analyzed in Gale crater, the diversity in diagenetic processes is primarily captured by the mineralogy and X-ray amorphous chemistry of the drilled rocks. Variations indicate a transition from magnetite to hematite and an increase in matrix-associated sulfates suggesting intensifying influence from oxic, diagenetic fluids upsection. Furthermore, diagenetic fluid pathways are shown to be strongly affected by unconformities and sedimentary transitions, as evidenced by the intensity of alteration inferred from the mineralogy of sediments sampled adjacent to stratigraphic contacts.

Chemistry, mineralogy, and grain properties at Namib and High dunes, Bagnold dune field, Gale crater, Mars: A synthesis of Curiosity rover observations.

The Mars Science Laboratory Curiosity rover performed coordinated measurements to examine the textures and compositions of aeolian sands in the active Bagnold dune field. The Bagnold sands are rounded to subrounded, very fine to medium sized (~45-500 µm) with ≥6 distinct grain colors. In contrast to sands examined by Curiosity in a dust-covered, inactive bedform called Rocknest and soils at other landing sites, Bagnold sands are darker, less red, better sorted, have fewer silt-sized or smaller grains, and show no evidence for cohesion. Nevertheless, Bagnold mineralogy and Rocknest mineralogy are similar with plagioclase, olivine, and pyroxenes in similar proportions comprising >90% of crystalline phases, along with a substantial amorphous component (35% ± 15%). Yet Bagnold and Rocknest bulk chemistry differ. Bagnold sands are Si enriched relative to other soils at Gale crater, and H2O, S, and Cl are lower relative to all previously measured Martian soils and most Gale crater rocks. Mg, Ni, Fe, and Mn are enriched in the coarse-sieved fraction of Bagnold sands, corroborated by visible/near-infrared spectra that suggest enrichment of olivine. Collectively, patterns in major element chemistry and volatile release data indicate two distinctive volatile reservoirs in Martian soils: (1) amorphous components in the sand-sized fraction (represented by Bagnold) that are Si-enriched, hydroxylated alteration products and/or H2O- or OH-bearing impact or volcanic glasses and (2) amorphous components in the fine fraction (<40 µm; represented by Rocknest and other bright soils) that are Fe, S, and Cl enriched with low Si and adsorbed and structural H2O.

The clinical safety and efficacy of ketoconazole in the prevention of postoperative erection: A systematic review

@#<p style="text-align: justify;"><strong>OBJECTIVE:</strong> To identify and assess the available literature in evaluating the efficacy and safety of ketoconazole in preventing postoperative erection among patients who underwent penile or urethral reconstructive surgery.<br /><strong>METHODS:</strong> From the period of 1990 to September 2016, the investigators assessed Cochrane Central Register of Controlled Trials, EMBASE, HERDIN, and PubMed for studies evaluating the efficacy and safety of ketoconazole in preventing post operative erection among patients who underwent penile or urethral reconstructive surgery. Review authors selected articles for inclusion, extracted date and and assessed trial quality.<br /><strong>RESULTS:</strong> One randomized controlled study and 2 retrospective studies were included in the review. Three studies for a total of 83 patients ages 17-32 comprised the evidence for this review. All trials investigated the efficacy and safety of ketoconazole in the prevention of post operative erection. In both retrospective studies, ketoconazole had significant prevention of erection in however both of these studies were non-RCTs. In the randomized control study by DeCastro et.al.,ketoconazole had no significant difference in the prevention of post operative erection against placebo. Sixteen out of 19 patients (84%) taking ketoconazole had episodes of erection and 15 out of 18 patients in the placebo group (83%) had episodes of erection. Common side effects include nausea (9-21%) and elevated liver enzymes (0-5.3%). Other reported adverse events include feet swelling,pruritus,frequent urination and headache. Present in only 1 out of the 31 patients (3.2%) in the study of DeCastro. All these adverse events were not statistically significant.<br /><strong>CONCLUSION:</strong> This review demonstrated that the use of Ketoconazole in the prevention of postoperative erection remains inconclusive. Further prospective randomized controlled trials with testosterone assay will help determine the appropriate dose and its efficacy in the prevention of postoperative erections. Ketoconazole is relatively safe if target testosterone levels are achieved using the 400mg/tab TID dosing.</p>

The clinical safety and efficacy of ketoconazole in the prevention of postoperative erection: A systematic review

OBJECTIVE: To identify and assess the available literature in evaluating the efficacy and safety of ketoconazole in preventing postoperative erection among patients who underwent penile or urethral reconstructive surgery.METHODS: From the period of 1990 to September 2016, the investigators assessed Cochrane Central Register of Controlled Trials, EMBASE, HERDIN, and PubMed for studies evaluating the efficacy and safety of ketoconazole in preventing post operative erection among patients who underwent penile or urethral reconstructive surgery. Review authors selected articles for inclusion, extracted date and and assessed trial quality.RESULTS: One randomized controlled study and 2 retrospective studies were included in the review. Three studies for a total of 83 patients ages 17-32 comprised the evidence for this review. All trials investigated the efficacy and safety of ketoconazole in the prevention of post operative erection. In both retrospective studies, ketoconazole had significant prevention of erection in however both of these studies were non-RCTs. In the randomized control study by DeCastro et.al.,ketoconazole had no significant difference in the prevention of post operative erection against placebo. Sixteen out of 19 patients (84%) taking ketoconazole had episodes of erection and 15 out of 18 patients in the placebo group (83%) had episodes of erection. Common side effects include nausea (9-21%) and elevated liver enzymes (0-5.3%). Other reported adverse events include feet swelling,pruritus,frequent urination and headache. Present in only 1 out of the 31 patients (3.2%) in the study of DeCastro. All these adverse events were not statistically significant.CONCLUSION: This review demonstrated that the use of Ketoconazole in the prevention of postoperative erection remains inconclusive. Further prospective randomized controlled trials with testosterone assay will help determine the appropriate dose and its efficacy in the prevention of postoperative erections. Ketoconazole is relatively safe if target testosterone levels are achieved using the 400mg/tab TID dosing.

Mineralogy of a mudstone at Yellowknife Bay, Gale crater, Mars.

Sedimentary rocks at Yellowknife Bay (Gale crater) on Mars include mudstone sampled by the Curiosity rover. The samples, John Klein and Cumberland, contain detrital basaltic minerals, calcium sulfates, iron oxide or hydroxides, iron sulfides, amorphous material, and trioctahedral smectites. The John Klein smectite has basal spacing of ~10 angstroms, indicating little interlayer hydration. The Cumberland smectite has basal spacing at both ~13.2 and ~10 angstroms. The larger spacing suggests a partially chloritized interlayer or interlayer magnesium or calcium facilitating H2O retention. Basaltic minerals in the mudstone are similar to those in nearby eolian deposits. However, the mudstone has far less Fe-forsterite, possibly lost with formation of smectite plus magnetite. Late Noachian/Early Hesperian or younger age indicates that clay mineral formation on Mars extended beyond Noachian time.

X-ray diffraction results from Mars Science Laboratory: mineralogy of Rocknest at Gale crater.

The Mars Science Laboratory rover Curiosity scooped samples of soil from the Rocknest aeolian bedform in Gale crater. Analysis of the soil with the Chemistry and Mineralogy (CheMin) x-ray diffraction (XRD) instrument revealed plagioclase (~An57), forsteritic olivine (~Fo62), augite, and pigeonite, with minor K-feldspar, magnetite, quartz, anhydrite, hematite, and ilmenite. The minor phases are present at, or near, detection limits. The soil also contains 27 ± 14 weight percent x-ray amorphous material, likely containing multiple Fe(3+)- and volatile-bearing phases, including possibly a substance resembling hisingerite. The crystalline component is similar to the normative mineralogy of certain basaltic rocks from Gusev crater on Mars and of martian basaltic meteorites. The amorphous component is similar to that found on Earth in places such as soils on the Mauna Kea volcano, Hawaii.

Curiosity at Gale crater, Mars: characterization and analysis of the Rocknest sand shadow.

The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand <150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations.