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NWA 8785 is a remarkable, recently identified, unequilibrated enstatite chondrite. It was classified as an EL3 but contains highly unusual characteristics not observed in any other EL3, including a high abundance of FeO‐rich matrix and metal‐rich nodules that are texturally and mineralogically different from those in other EL3s. We characterized the mineral assemblages and compositions of metal‐rich nodules in a thin section of NWA 8785 and compared them to nodules in other EL3s to evaluate models for formation of metal‐rich nodules in EL3s. Of a total of 40 metal‐rich nodules, 10 were selected for detailed study. These metal‐rich nodules vary in their physical structure, texture, and mineral assemblages. Some contain the rare Al‐poor, alkali‐rich silicate mineral roedderite, a first discovery in an EL3, as well as the Cl‐bearing sulfide djerfisherite. The diversity of metal‐rich nodules in NWA 8785 suggests each nodule formed independently and supports their origin by primary processes prior to accretion. The high abundance of FeO‐rich matrix and the unique qualities of its metal‐rich nodules call into question classification of NWA 8785 as an EL3, but the Si content in its kamacite and Cr and Ti content in its troilite, and the presence of alabandite, support its classification as an EL3; thus, it is an EL3‐anomalous. Although alternative hypotheses exist, the presence of roedderite, as well as a magnetite‐rich matrix and sodalite, may provide the first evidence of extensive metasomatic alteration on the EL3 parent body. [ABSTRACT FROM AUTHOR]

Opaque assemblages (OAs) are small (submillimeter) objects composed primarily of metals, sulfides, and oxides that exist in nearly all chondritic meteorite groups as discrete objects in the matrix or associated with chondrules. The size, morphology, and petrology of OAs vary greatly between different chondrite groups, with petrologic grade within a single group, and by their apparent textural setting. Two hypotheses may explain the formation of matrix OAs: (1) they were separated from chondrules via surface tension during heating events, or (2) they formed as free‐floating objects in the solar nebula; however, this is the first comprehensive study of the petrology of OAs in ordinary chondrites (OCs) as a group, which seeks to determine if one hypothesis is sufficient to explain all such objects. Here, we use a newly developed machine learning algorithm to show that all OAs from the least equilibrated OC, Semarkona (LL 3.01), are composed of kamacite, taenite, troilite, pentlandite, magnetite, and other minor phases. These OAs form two distinct groups based on their modal mineralogy: one group in and associated with chondrules, and the other group free‐floating in the matrix. Chondrule OAs exhibit a bimodal distribution between sulfide‐ and metal‐rich endmembers in agreement with previous findings. Matrix OAs cluster at roughly equal abundances of sulfides and metals and universally exhibit magnetite rims. The two populations of chondrule OAs cannot be combined to form the modal mineralogies observed in matrix OAs and some matrix OAs exhibit mineralogical layering consistent with fractional condensation. Both observations support the hypothesis that matrix OAs were not formed by expulsion from chondrules and instead formed as free‐floating objects in the solar nebula; however, chondrule OAs must have formed with their host chondrules during heating events. [ABSTRACT FROM AUTHOR]

PURPOSE The purpose of this review is to quantify response to radiotherapy delivered early in the active inflammatory phase of moderate-to-severe Graves' ophthalmopathy. MATERIALS AND METHODS A retrospective review of radiotherapy delivered early in the active phase of Graves' ophthalmopathy was performed. All 47 cases had moderate-to-severe ophthalmopathy, and 30 cases had optic neuropathy. Variables examined included exophthalmos, color vision, and resistance to retropulsion. Statistical analyses comparing these variables at presentation and at 3 and 6 months after radiotherapy were performed. Subset analyses comparing responses of patients with symptoms lasting longer or less than 6 months were also performed. RESULTS At 6 months after radiotherapy, there was improvement in exophthalmos in 74.5% of cases and improvement in retropulsion in 83.0%, and all cases of previous color deficiency improved. The mean improvement in exophthalmos was 1.38 mm, color vision was two plates, and retropulsion was 1 grade. On subset analyses, there was a trend toward greater improvement in patients treated earlier in the course of their symptoms. CONCLUSIONS Radiotherapy may play an important role in the treatment of Graves' ophthalmopathy, especially for patients with optic neuropathy. Early intervention (symptoms < 6 months) with radiotherapy may be the optimal timing for this treatment. [ABSTRACT FROM AUTHOR]