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Duprat, J.

Publications and source records attributed to Duprat, J..

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples

Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed 17 Ryugu samples measuring 1 to 8 millimeters. Carbon dioxide–bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu’s parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and calcium- and aluminum-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed through aqueous alteration reactions at low temperature, high pH, and water/rock ratios of <1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate that Ryugu’s parent body formed ~2 million years after the beginning of Solar System formation.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2020

Organic Matter in the Aguas Zarcas (CM2) Meteorite: High Abundance of Aliphatic Carbon in Metal-Rich Lithology

The Aguas Zarcas meteorite is a new CM2 chondrite which fell on 23 April 2019 (local time) in Costa Rica. Aguas Zarcas is brecciated and contains several different lithologies, e.g., metal-rich lithology and CI-like lithology. This fresh CM2 chondrite gives us good op-portunities for analyses of organic matter (OM) without terrestrial contamination and weathering, particularly some stones which were collected before rain fell over the fall site. We also aim to characterize local hetero-geneities and associations of organic and mineral phases using state-of-the-art microscopic techniques to con-strain the origin and evolutionally processes of OM during pre- and post-accretion.

Kebukawa, Y.↗
DOE OSTI2019

Inguinal and Ilio-inguinal Lymphadenectomy in Management of Palpable Melanoma Lymph Node Metastasis: A Long-Term Prospective Evaluation of Morbidity and Quality of Life

Purpose: Prospective data are lacking on long-term morbidity of inguinal lymphadenectomy including the influence of extent of surgery, use of radiotherapy, and patient factors. The aim of this study is to evaluate the effects of these factors on patient outcome, quality of life (QOL), regional symptoms, and limb volumes after inguinal or ilio-inguinal lymphadenectomy for melanoma. Methods: Analysis of the subgroup of patients with inguinal lymph node field relapse of melanoma, treated by inguinal or ilio-inguinal lymphadenectomy in the ANZMTG/TROG randomized trial of adjuvant radiotherapy versus observation. Results: Sixty-nine patients, 46 having undergone inguinal and 23 ilio-inguinal lymphadenectomy, with median follow-up of 73 months were analyzed. Mean limb volume increased rapidly after surgery (7% by 3 months) and continued to increase for at least another 18 months. Patients with body mass index (BMI) ≥ 25 kg/m{sup 2} had greater limb volume increase than normal-weight patients (13.3% versus 6.9%, P = 0.030). QOL improved over the first 18 months, but despite initial improvement, regional symptoms persisted long term. Type of surgery (inguinal or ilio-inguinal lymphadenectomy) had no demonstrably significant effect on limb volume (9.9% versus 13.4%, P = 0.35), QOL (P = 0.68), or regional symptoms (P = 0.65). There was no difference in overall survival between inguinal and ilio-inguinal lymphadenectomy [hazard ratio (HR) 0.75, 95% confidence interval (CI) 0.40–1.40, P = 0.43]. Conclusions: Inguinal lymphadenectomy for melanoma is a potentially morbid procedure with significant increases in limb volume. Patients report reasonable QOL but may have ongoing regional symptoms. Overweight/obesity is associated with poorer QOL, increased limb volume, and regional symptoms.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2013

C/N and other Elemental Ratios of Chondritic Porous IDPS and a Fluffy Concordia Micrometeorite

Chondritic porous interplanetary dust particles (CP-IDPs) may be cometary in origin [1], as may ultracarbona-ceous (UCAMMs) [2] and 'fluffy' [3] micrometeorites from the Concordia collection. They are all rich in organics, which can rim grains and may have helped glue grains together during accretion [4]. The organics also contain nitrogen the input of which to Earth has potential biological importance. We report C/N ratios, and other properties of CP-IDPs and a Concordia fluffy microme-teorite.

Smith, T.↗
NASA NTRS2003

About Tagish Lake as a Potential Parent Body for Polar Micrometeorites; Clues from their Hydrogen Isotopic Compositions

The origin of the Antarctic micrometeorites (AMMs) is still a matter of debate. Their closest meteoritic counterparts are the C2 chondrites, but the match is not perfect, and the parent body(ies) of the AMMs is(are) still to be identified. Tagish Lake is a new meteorite fall which bears similarity with CI1 and CM2 chondrites, but is distinct from both. Based on the mineralogy of phyllosilicates, Noguchi et al. proposed that the phyllosilicate-rich AMMs and the Tagish Lake meteorites could derive from similar asteroids. The hydrogen isotopic compositions of extra-terrestrial samples can be used to get some insight on their origin. The D/H ratios of AMMs and of Tagish Lake have been measured, but using different analytical techniques. They are therefore not directly comparable. We performed additional hydrogen isotopic analyses of fragments of Tagish Lake using the same experimental setup previously used for the measurement of the hydrogen isotopic composition of AMMs. In this work, we could also analyze separately both lithologies of Tagish Lake (carbonate-poor and -rich). The distributions of delta D values measured in the two lithologies of Tagish Lake are very similar, indicating that fluids with similar hydrogen isotopic compositions altered the meteorite on the parent body for the two lithologies. Yet, the hydrogen isotopic composition of Tagish Lake is different from that of AMMs, suggesting that they do not derive from the same parent body.

Engrand, C.↗