Short-Term Outcomes, Functional Status, and Risk Factors for Requiring Extracorporeal Life Support After Norwood Operation: A Single-Center Retrospective Study.

Patients requiring extracorporeal life support (ECLS) post-Norwood operation constitute an extremely high-risk group. We retrospectively described short-term outcomes, functional status, and assessed risk factors for requiring ECLS post-Norwood operation between January 2010 and December 2020 in a high-volume center. During the study period, 269 patients underwent a Norwood procedure of which 65 (24%) required ECLS. Of the 65 patients, 27 (41.5%) survived to hospital discharge. Mean functional status scale (FSS) score at discharge increased from 6.0 on admission to 8.48 (p < 0.0001). This change was primary in feeding (p < 0.0001) and respiratory domains (p = 0.017). Seven survivors (26%) developed new morbidity, and two (7%) developed unfavorable functional outcomes. In the regression analysis, we showed that patients with moderate-severe univentricular dysfunction on pre-Norwood transthoracic echocardiogram (odds ratio [OR] = 6.97), modified Blalock Taussig Thomas (m-BTT) shunt as source of pulmonary blood flow (OR = 2.65), moderate-severe atrioventricular valve regurgitation on transesophageal echocardiogram (OR = 8.50), longer cardiopulmonary bypass time (OR = 1.16), longer circulatory arrest time (OR = 1.20), and delayed sternal closure (OR = 3.86), had higher odds of requiring ECLS (p < 0.05). Careful identification of these risk factors is imperative to improve the care of this high-risk cohort and improve overall outcomes.

Characteristics of conventional high-risk coronary plaques and a novel CT defined thin-cap fibroatheroma in patients undergoing CCTA with stable chest pain.

BACKGROUND: Coronary computed tomography angiography (CCTA) can identify high-risk coronary plaque types. However, the inter-observer variability for high-risk plaque features, including low attenuation plaque (LAP), positive remodelling (PR), and the Napkin-Ring sign (NRS), may reduce their utility, especially amongst less experienced readers. METHODOLOGY: In a prospective study, we compared the prevalence, location and inter-observer variability of both conventional CT-defined high-risk plaques with a novel index based on quantifying the ratio of necrotic core to fibrous plaque using individualised X-ray attenuation cut-offs (the CT-defined thin-cap fibroatheroma - CT-TCFA) in 100 patients followed-up for 7 years. RESULTS: In total, 346 plaques were identified in all patients. Seventy-two (21%) of all plaques were classified by conventional CT parameters as high-risk (either NRS or PR and LAP combined), and 43 (12%) of plaques were considered high-risk using the novel CT-TCFA definition of (Necrotic Core/fibrous plaque ratio of >0.9). The majority (80%) of the high-risk plaques (LAP&PR, NRS and CT-TCFA) were located in the proximal and mid-LAD and RCA. The kappa co-efficient of inter-observer variability (k) for NRS was 0.4 and for PR and LAP combined 0.4. While the kappa co-efficient of inter-observer variability (k) for the new CT-TCFA definition was 0.7. During follow-up, patients with either conventional high-risk plaques or CT-TCFAs were significantly more likely to have MACE (Major adverse cardiovascular events) compared to patients without coronary plaques (p value 0.03 & 0.03, respectively). CONCLUSION: The novel CT-TCFA is associated with MACE and has improved inter-observer variability compared with current CT-defined high-risk plaques.

Utility of cephalic drains in infants receiving extracorporeal membrane oxygenation.

INTRODUCTION: The addition of cephalic drains (CDs) in extracorporeal membrane oxygenation (ECMO) to augment venous drainage may offer benefit, though their use is varied. Our objective was to describe our institution's experience with CDs including flow rates and patency. We also compared complication rates between patients with and without a CD. METHODS: This retrospective cohort study included infants <12 months of age cannulated for ECMO between January 1, 2010 and September 30, 2019 at a single institution. Flow data were obtained for those with a CD. Demographic and complication rates were obtained for all. RESULTS: Of 264 patients in the final cohort, 220 (83%) had a CD of which 93.2% remained patent to decannulation. CDs typically provided 30% or more of ECMO flow throughout the ECMO run. The median time to CD clot was 139 h (range 48-635 h). Patients with a clotted CD had longer ECMO runs than those whose CD remained patent (median 382 h [IQR 217-538] vs 139 h [IQR 91-246], p < 0.001). Survival to discharge was lower for those with clotted versus patent CD (14% vs 70%, p < 0.001). Mechanical complications were more common in patients with CD (p = 0.005). Seizures were more common in those without a CD (p = 0.021). CONCLUSIONS: In this cohort, the majority of CDs placed remained patent at decannulation and provided substantial additional venous drainage. Mechanical problems were common in patients with CDs, but without clinical sequelae. Further study is warranted to elucidate CD impact on short- and long-term outcomes.

Measures of anticoagulation and coagulopathy in pediatric cardiac extracorporeal membrane oxygenation patients.

INTRODUCTION: Pediatric cardiac Extracorporeal Membrane Oxygenation (ECMO) is effective, however, bleeding and clotting issues continue to cause significant morbidity and mortality. The objective of this study was to assess the correlation between measures of anticoagulation, the heparin dose in pediatric cardiac ECMO patients as well as to assess covert coagulopathy as measured by thromboelastography (TEG). METHODS: Retrospective study of cardiac ECMO patients in a large, academic referral center using anticoagulation data during the ECMO support. RESULTS: Five hundred and eighty-four sets of anticoagulation tests and 343 TEG from 100 patients with median age of 26 days were reviewed. ECMO was post-surgical for congenital heart disease in 94% with resuscitation (ECPR) in 38% of the cases. Mean duration of support was 6.3 days. Overall survival to discharge was 35%. There was low but statistically significant correlation between individual anticoagulation measures and low correlation between Anti-Xa levels and heparin dose. There was no correlation between PTT and heparin dose. 343 TEG with Heparinase were reviewed to assess covert coagulopathy which was present in 25% of these. The coagulopathy noted was pro-hemorrhagic in almost all of the cases with high values of reaction time and kinetics and low values for angle and maximum amplitude. CONCLUSION: Coagulation monitoring on ECMO may benefit from addition of Heparinase TEG to diagnose covert coagulopathy which can contribute to significant hemorrhagic complications. There is a need for a prospective, thromboelastography guided intervention trial to reduce coagulopathy related morbidity and mortality in ECMO.

Insight Into Disorder, Stress and Strain of Radiation Damaged Pyrochlores: A Possible Mechanism for the Appearance of Defect Fluorite.

We have examined the irradiation response of a titanate and zirconate pyrochlore-both of which are well studied in the literature individually-in an attempt to define the appearance of defect fluorite in zirconate pyrochlores. To our knowledge this study is unique in that it attempts to discover the mechanism of formation by a comparison of the different systems exposed to the same conditions and then examined via a range of techniques that cover a wide length scale. The conditions of approximately 1 displacement per atom via He2+ ions were used to simulate long term waste storage conditions as outlined by previous results from Ewing in a large enough sample volume to allow for neutron diffraction, as not attempted previously. The titanate sample, used as a baseline comparison since it readily becomes amorphous under these conditions behaved as expected. In contrast, the zirconate sample accumulates tensile stress in the absence of detectable strain. We propose this is analogous to the lanthanide zirconate pyrochlores examined by Simeone et al. where they reported the appearance of defect fluorite diffraction patterns due to a reduction in grain size. Radiation damage and stress results in the grains breaking into even smaller crystallites, thus creating even smaller coherent diffraction domains. An (ErNd)2(ZrTi)2O7 pyrochlore was synthesized to examine which mechanism might dominate, amorphization or stress/strain build up. Although strain was detected in the pristine sample via Synchrotron X-ray diffraction it was not of sufficient quality to perform a full analysis on.

Clinical and Hematological Outcomes of Aminocaproic Acid Use During Pediatric Cardiac ECMO.

Bleeding and thrombosis-related complications are common in pediatric cardiac patients supported by extracorporeal membrane oxygenation (ECMO) and are associated with morbidity and mortality. The purpose of this study was to evaluate the utility of aminocaproic acid (ACA), an antifibrinolytic agent, as it pertains to bleeding in pediatric cardiac patients on ECMO. This included a retrospective cohort study of pediatric cardiac patients receiving ACA while supported on ECMO between 2013 and 2017. For each patient, data were collected in three time intervals: the 24 hours before ACA initiation, and then 0-24 and 24-48 hours following ACA initiation. For each time frame, bleeding, component transfusion, and laboratory data were collected and analyzed. A total of 62 patients were included, representing 42% of our cardiac ECMO patients during the time period. ACA was initiated at 16.3 ± 8.7 hours following initiation of ECMO. The mean bleeding rate before ACA was 10.57 mL/kg/h, which reduced to 7.8 mL/kg/h in the 24-hour period after initiation of ACA and a further decrease to 3.65 mL/kg/h during the 24- to 48-hour time period following ACA initiation. ACA administration was associated with reduction in bleeding (p < .001) and packed red blood cell transfusions (p = .02), administration of fresh frozen plasma (p < .001), platelets (p = .017), cryoprecipitate (p = .05), factor VII (p = .002), and Cell Saver (p = .005). Hemoglobin and platelet count were stable, whereas prothrombin time (PT), partial thromboplastin time, and international normalized ratio (INR) showed significant reduction over the time course. ACA administration was not associated with specific adverse effects. A clinically significant reduction in bleeding amount, red blood cell transfusions, and other hematologic interventions occurred following ACA administration for pediatric patients on ECMO. Wider consideration for ACA use as a part of a multipronged strategy to manage bleeding during ECMO should be considered.

Oxia Planum: The Landing Site for the ExoMars "Rosalind Franklin" Rover Mission: Geological Context and Prelanding Interpretation.

The European Space Agency (ESA) and Roscosmos ExoMars mission will launch the "Rosalind Franklin" rover in 2022 for a landing on Mars in 2023.The goals of the mission are to search for signs of past and present life on Mars, investigate the water/geochemical environment as a function of depth in the shallow subsurface, and characterize the surface environment. To meet these scientific objectives while minimizing the risk for landing, a 5-year-long landing site selection process was conducted by ESA, during which eight candidate sites were down selected to one: Oxia Planum. Oxia Planum is a 200 km-wide low-relief terrain characterized by hydrous clay-bearing bedrock units located at the southwest margin of Arabia Terra. This region exhibits Noachian-aged terrains. We show in this study that the selected landing site has recorded at least two distinct aqueous environments, both of which occurred during the Noachian: (1) a first phase that led to the deposition and alteration of ∼100 m of layered clay-rich deposits and (2) a second phase of a fluviodeltaic system that postdates the widespread clay-rich layered unit. Rounded isolated buttes that overlie the clay-bearing unit may also be related to aqueous processes. Our study also details the formation of an unaltered mafic-rich dark resistant unit likely of Amazonian age that caps the other units and possibly originated from volcanism. Oxia Planum shows evidence for intense erosion from morphology (inverted features) and crater statistics. Due to these erosional processes, two types of Noachian sedimentary rocks are currently exposed. We also expect rocks at the surface to have been exposed to cosmic bombardment only recently, minimizing organic matter damage.

Anatomical and biochemical evidence for Treponema pallidum in a 19th to early twentieth century skeletal cadaver.

This report summarizes findings relating to the biochemical and skeletal evidence for Treponema pallidum in an unusually old case of congenital syphilis. In 1951, the Milwaukee Public Museum acquired skeletal remains from the Surgical School of Marquette University. The male was identified as a 60-65-year-old, that was suffering from congenital syphilis. His remains are now part of the anthropological collections of Wisconsin Lutheran College (Milwaukee, Wisconsin). Venereal Disease Research Laboratory (VDRL) and Rapid Plasma Reagin (RPR) tests were used to verify the presence of the bacteria-generated antibodies, while mass spectrometry testing provided indirect evidence for the historical treatment of the disease. Notably, antibody detection in human remains of this age is rare. These initial results support what is known of syphilis and its treatment prior to the wide scale, clinical use of penicillin therapy, and describe evidence for long-term skeletal symptoms of congenital syphilis in century-old human remains.

Sustained fluvial deposition recorded in Mars' Noachian stratigraphic record.

Orbital observation has revealed a rich record of fluvial landforms on Mars, with much of this record dating 3.6-3.0 Ga. Despite widespread geomorphic evidence, few analyses of Mars' alluvial sedimentary-stratigraphic record exist, with detailed studies of alluvium largely limited to smaller sand-bodies amenable to study in-situ by rovers. These typically metre-scale outcrop dimensions have prevented interpretation of larger scale channel-morphology and long-term basin evolution, vital for understanding the past Martian climate. Here we give an interpretation of a large sedimentary succession at Izola mensa within the NW Hellas Basin rim. The succession comprises channel and barform packages which together demonstrate that river deposition was already well established >3.7 Ga. The deposits mirror terrestrial analogues subject to low-peak discharge variation, implying that river deposition at Izola was subject to sustained, potentially perennial, fluvial flow. Such conditions would require an environment capable of maintaining large volumes of water for extensive time-periods, necessitating a precipitation-driven hydrological cycle.

Factors Associated With Survival Following Extracorporeal Cardiopulmonary Resuscitation in Children.

OBJECTIVES: We examined a large single-institution experience in extracorporeal cardiopulmonary resuscitation (ECPR) in children having cardiac arrest refractory to conventional resuscitation measures with focus on factors affecting survival. METHODS: Between 2002 and 2017, 184 children underwent ECPR at our institution. We entered demographic, anatomic, clinical, surgical, and ECPR support details into a multivariable logistic regression models to determine factors associated with mortality. RESULTS: Median age was 54 days (interquartile range [IQR]: 11-272). In all, 157 (85%) patients had primary cardiac disease, including 136 (74%) with congenital heart disease (71 with single ventricle). Extracorporeal cardiopulmonary resuscitation occurred following cardiac surgery in 124 (67%) patients. Median cardiopulmonary resuscitation (CPR) duration was 27 minutes (IQR: 18-40) and median support duration was 3.0 days (IQR: 1.6-5.3). Overall, ECPR was weaned in 115 (63%), with 79 (43%) surviving to hospital discharge. Survival for patients with congenital heart disease, noncongenital cardiac, and noncardiac pathologies was 44%, 71%, and 15%, respectively. On multivariable regression analysis, risk factors associated with mortality were presupport pH <7.1 (odds ratio [OR] = 3.7, 95% confidence interval [CI]: 1.11-12.41, P = .033), mechanical complications (OR = 8.33, 95% CI: 1.91-36.25, P = .005), neurologic complications (OR = 6.27, 95% CI: 1.40-28.10, P = .017), and renal replacement therapy (OR = 3.31, 95% CI: 1.03-10.66, P = .045). CONCLUSIONS: Extracorporeal cardiopulmonary resuscitation plays a valuable role salvaging children with refractory cardiac arrest. Survival varies with underlying pathology and can be expected even with relatively longer CPR durations. Efforts to improve systemic output before and after institution of ECPR might mitigate some of the significant risk factors for mortality.

Blood product transfusion and mortality in neonatal extracorporeal membrane oxygenation.

BACKGROUND: Neonates receiving extracorporeal membrane oxygenation (ECMO) support are transfused large volumes of red blood cells (RBCs) and platelets (PLTs). Transfusions are often administered in response to specific, but largely unstudied thresholds. The aim of this study is to examine the relationship between RBC and PLT transfusion rates and mortality in neonates receiving ECMO support. STUDY DESIGN AND METHODS: We retrospectively examined outcomes of neonates receiving ECMO support in the neonatal intensive care unit (NICU) for respiratory failure between 2010 and 2016 at a single quaternary-referral NICU. We examined the association between RBC and PLT transfusion rate (mL per kg per day) and in-hospital mortality, adjusting for confounding by using a validated composite baseline risk score (Neo-RESCUERS). RESULTS: Among the 110 neonates receiving ECMO support, in-hospital mortality was 28%. The median RBC transfusion rate (mL/kg/d) after cannulation was greater among non-survivors, compared to survivors: 12.4 (IQR 9.3-16.2) versus 7.3 (IQR 5.1-10.3), p < 0.001. Similarly, PLT transfusion rate was greater among non-survivors: 22.9 (9.3-16.2) versus 12.1 (8.4-20.1), p = 0.02. After adjusting for baseline mortality risk, both RBC transfusion (adjusted relative risk per 5 mL/kg/d increase: 1.33; 95% CI 1.05-1.69, p = 0.02) and PLT transfusion (adjusted relative risk per 5 mL/kg/d increase: 1.12; 95% CI 1.02-1.23, p = 0.02) were both associated with in-hospital mortality. CONCLUSIONS: RBC and PLT transfusion rates are associated with in-hospital mortality among neonates receiving ECMO. These data provide a basis for future studies evaluating more restrictive transfusion practices for neonates receiving ECMO support.

Functional Movement Screen (FMS™) Scores and Demographics of US Army Pre-Ranger Candidates.

INTRODUCTION: The United States Army Rangers are a unique population whose training requirements are intensive, and physically and mentally demanding. The Functional Movement Screen (FMS) is a movement screening tool designed to assess movement quality and asymmetries in movement with the potential to identify injury risk. This study was a descriptive, cross-sectional investigation examining associations between FMS scores and the various measures of health and performance of active duty soldiers in light infantry units who were involved in the U.S. Army Pre-Ranger Course (PRC). MATERIALS AND METHODS: Before the PRC, 491 male soldiers (mean age = 24.0 ± 3.8 years; mean height = 176.6 ± 7.2 cm; mean body mass = 80.2 ± 9.8 kg) completed a questionnaire which included items on self-assessed physical fitness, last Army physical fitness test (APFT) score, tobacco use, and injury history. The soldiers then completed the FMS, which consisted of seven movements and three clearing tests. From the FMS results, a determination of asymmetries (i.e., differences in FMS scores between the right and left side of the body) was made. Differences between groups were analyzed via an independent sample t-test, a one-way analysis of variance, or a chi-square as appropriate. Significance was set at 0.05 a priori. RESULTS: The average composite FMS score was 16.4 (±1.9) points. Soldiers reporting ≥290 APFT points achieved a higher FMS score than those reporting lower APFT scores (16.5 ± 2.0 vs 16.1 ± 2.0 points, P = 0.03). Soldiers reporting either tobacco use or a previous musculoskeletal injury had lower FMS scores than those not reporting these (tobacco: 16.1 ± 2.1 vs 16.5 ± 1.8 points, P = 0.02; injury: 16.0 ± 2.2 vs 16.6 ± 1.8 points, P < 0.01). FMS asymmetries were not related to APFT scores, tobacco use, or self-rated fitness. As self-rated fitness increased so did APFT scores. CONCLUSIONS: Active duty soldiers of a light infantry division achieved FMS scores similar to other military populations tested, and the composite FMS score was related to higher APFT scores, absence of tobacco use, and absence of previous musculoskeletal injuries. Improving PRC candidate healthy habits through highlighting the negative associations between poorer fitness, cigarette tobacco use and movement quality, may reduce injury risk and increase PRC completion potential.

A Diverse Array of Fluvial Depositional Systems in Arabia Terra: Evidence for mid-Noachian to Early Hesperian Rivers on Mars.

Branching to sinuous ridges systems, hundreds of kilometers in length and comprising layered strata, are present across much of Arabia Terra, Mars. These ridges are interpreted as depositional fluvial channels, now preserved as inverted topography. Here we use high-resolution image and topographic data sets to investigate the morphology of these depositional systems and show key examples of their relationships to associated fluvial landforms. The inverted channel systems likely comprise indurated conglomerate, sandstone, and mudstone bodies, which form a multistory channel stratigraphy. The channel systems intersect local basins and indurated sedimentary mounds, which we interpret as paleolake deposits. Some inverted channels are located within erosional valley networks, which have regional and local catchments. Inverted channels are typically found in downslope sections of valley networks, sometimes at the margins of basins, and numerous different transition morphologies are observed. These relationships indicate a complex history of erosion and deposition, possibly controlled by changes in water or sediment flux, or base-level variation. Other inverted channel systems have no clear preserved catchment, likely lost due to regional resurfacing of upland areas. Sediment may have been transported through Arabia Terra toward the dichotomy and stored in local and regional-scale basins. Regional stratigraphic relations suggest these systems were active between the mid-Noachian and early Hesperian. The morphology of these systems is supportive of an early Mars climate, which was characterized by prolonged precipitation and runoff.

Inotrope Needs in Neonates Requiring Extracorporeal Membrane Oxygenation for Respiratory Failure.

OBJECTIVE: To evaluate how inotropic requirements in neonates with respiratory failure are affected by extracorporeal membrane oxygenation (ECMO) mode and whether high requirements predict mortality. STUDY DESIGN: This retrospective chart review included all neonates undergoing ECMO for primary respiratory failure from 2010 to 2016 at a single institution. The vasoactive inotropy score (VIS) was calculated as described in the literature. Data were analyzed with descriptive statistics and univariate analyses. RESULTS: Of the 110 identified neonates, 96 underwent venovenous (VV) (87%), 11 (10%) venoarterial, and 3 (3%) converted from VV to venoarterial. The median precannulation VIS score was 33.02 for patients who underwent VV compared with 28.93 for venoarterial (P = .25) and 15 for infants converted. VIS decreased dramatically by 4 hours of ECMO in both groups. The VIS before cannulation was similar in survivors and nonsurvivors, but was significantly higher in nonsurvivors after 24 hours of ECMO (median VIS, 12 [IQR, 8-25] vs 8 [IQR, 3.0-14.5]; P = .035) and at decannulation (10 [IQR, 7-19] vs 3 [IQR, 0-7]; P < .001). CONCLUSIONS: Neonates with respiratory failure can be successfully managed on VV ECMO even with considerable vasoactive requirements. Vasoactive requirement after 24 hours of ECMO was predictive of mortality.

Corrigendum: Impact of the Food Additive Titanium Dioxide (E171) on Gut Microbiota-Host Interaction.

[This corrects the article DOI: 10.3389/fnut.2019.00057.].

Impact of the Food Additive Titanium Dioxide (E171) on Gut Microbiota-Host Interaction.

The interaction between gut microbiota and host plays a central role in health. Dysbiosis, detrimental changes in gut microbiota and inflammation have been reported in non-communicable diseases. While diet has a profound impact on gut microbiota composition and function, the role of food additives such as titanium dioxide (TiO2), prevalent in processed food, is less established. In this project, we investigated the impact of food grade TiO2 on gut microbiota of mice when orally administered via drinking water. While TiO2 had minimal impact on the composition of the microbiota in the small intestine and colon, we found that TiO2 treatment could alter the release of bacterial metabolites in vivo and affect the spatial distribution of commensal bacteria in vitro by promoting biofilm formation. We also found reduced expression of the colonic mucin 2 gene, a key component of the intestinal mucus layer, and increased expression of the beta defensin gene, indicating that TiO2 significantly impacts gut homeostasis. These changes were associated with colonic inflammation, as shown by decreased crypt length, infiltration of CD8+ T cells, increased macrophages as well as increased expression of inflammatory cytokines. These findings collectively show that TiO2 is not inert, but rather impairs gut homeostasis which may in turn prime the host for disease development.

Biofilm-enhanced adsorption of strong and weak cations onto different microplastic sample types: Use of spectroscopy, microscopy and radiotracer methods.

The adsorption of metals and other elements onto environmental plastics has been previously quantified and is known to be enhanced by surface-weathering and development of biofilms. However, further biofilm-adsorption characterisation is needed with respect to the fate of radionuclides. This study uses spectroscopy, microscopy and radiotracer methods to investigate the adsorption capacity of relatively strong and weak cations onto different microplastic sample types that were conditioned in freshwater, estuarine and marine conditions although marine data were limited. Fourier-transform infrared spectroscopy confirmed that surface oxidation chemistry changes induced by gamma irradiation were similar to those resulting from environmental exposures. Microscopy elemental mapping revealed patchy biofilm development, which contained Si, Al, and O, consistent with microbial-facilitated capture of clays. The plastics+biofilm of all sample types had measurable adsorption for Cs and Sr radiotracers, suggesting environmental plastics act broadly as a sink for the key pervasive environmental radionuclides of 137Cs and 90Sr associated with releases from nuclear activities. Adsorption onto high-density polyethylene plastic types was greater than that on polypropylene. However, in most cases, the adsorption rates of all types of plastic+biofilm were much lower than those of reference sediments and roughly consistent with their relative exchangeable surface areas.

Persistence of intense, climate-driven runoff late in Mars history.

Mars is dry today, but numerous precipitation-fed paleo-rivers are found across the planet's surface. These rivers' existence is a challenge to models of planetary climate evolution. We report results indicating that, for a given catchment area, rivers on Mars were wider than rivers on Earth today. We use the scale (width and wavelength) of Mars paleo-rivers as a proxy for past runoff production. Using multiple methods, we infer that intense runoff production of >(3-20) kg/m2 per day persisted until <3 billion years (Ga) ago and probably <1 Ga ago, and was globally distributed. Therefore, the intense runoff production inferred from the results of the Mars Science Laboratory rover was not a short-lived or local anomaly. Rather, precipitation-fed runoff production was globally distributed, was intense, and persisted intermittently over >1 Ga. Our improved history of Mars' river runoff places new constraints on the unknown mechanism that caused wet climates on Mars.

The Quantification of Radiation Damage in Orthophosphates Using Confocal µ-Luminescence Spectroscopy of Nd3.

In this study, we present a new concept based on the steady-state, laser-induced photoluminescence of Nd3+, which aims at a direct determination of the amorphous fraction f a in monazite- and xenotime-type orthophosphates on a micrometer scale. Polycrystalline, cold-pressed, sintered LaPO4, and YPO4 ceramics were exposed to quadruple Au-ion irradiation with ion energies 35 MeV (50% of the respective total fluence), 22 MeV (21%), 14 MeV (16%), and 7 MeV (13%). Total irradiation fluences were varied in the range 1.6 × 1013-6.5 × 1013 ions/cm2. Ion-irradiation resulted in amorphization and damage accumulation unto a depth of ~5 µm below the irradiated surfaces. The amorphous fraction created was quantified by means of surface-sensitive grazing-incidence X-ray diffraction and photoluminescence spectroscopy using state-of-the-art confocal spectrometers with spatial resolution in the µm range. Monazite-type LaPO4 was found to be more susceptible to ion-irradiation induced damage accumulation than xenotime-type YPO4. Transmission electron microscopy of lamella cut from irradiated surfaces with the focused-ion beam technique confirmed damage depth-profiles with those obtained from PL hyperspectral mapping. Potential analytical advantages that arise from an improved characterization and quantification of radiation damage (i.e., f a) on the µm-scale are discussed.