Mn-53-Cr-53 Systematics of R-Chondrite NWA 753

Chondrules and chondrites are interpreted as objects formed in the early solar system, and it is important to study them in order to elucidate its evolution. Here, we report the study of the Mn-Cr systematics of the R-Chondrite NWA753 and compare the results to other chondrite data. The goal was to determine Cr isotopic and age variations among chondrite groups with different O-isotope signatures. The Mn-53-Cr-53 method as applied to individual chondrules [1] or bulk chondrites [2] is based on the assumption that 53Mn was initially homogeneously distributed in that portion the solar nebula where the chondrules and/or chondrites formed. However, different groups of chondrites formed from regions of different O-isotope compositions. So, different types of chondrites also may have had different initial Mn-53 abundances and/or Cr isotopic compositions. Thus, it is important to determine the Cr isotopic systematics among chondrites from various chondrite groups. We are studying CO-chondrite ALH83108 and Tagish Lake in addition to R-Chondrite NWA753. These meteorites have very distinct O-isotope compositions (Figure 1)

Varietal Adoption, Outcomes and Impact

Parallel to the preceding chapter, we synthesize the results of Chapters 6–17 here. The focus is on outcomes and impacts. Outcomes centre on varietal adoption and turnover; impacts refer to changes in on-farm productivity, poverty and food security. Hypotheses from Chapter 3 are revisited at the end of each thematic section..

Upaya Peningkatan Kompetensi Profesional Guru IPS dalam Proses Pembelajaran

Professional competence is a learning ability related to mastery of the material broadly and deeply. However, this is not in accordance with the observations of social studies teachers and junior high school principals that teachers experience difficulties in presenting economic material, limited sources of teaching materials and teaching media, and the method used is still limited to the KTSP method. This study aims to reveal the professional competence of social studies subject teachers in the learning process. The method used is a qualitative research with the subject of this research are social studies subject teachers and principals. Data collection techniques were carried out through interviews, observation and documentation. While the data analysis techniques used are data reduction, data presentation, and drawing conclusions. The results of the study reveal that social studies teachers have not fully met the professional competence of teachers. Efforts are being made to overcome this by involving social studies teachers in MGMP activities, seminars, training and Technical Guidance (Bimtek). Meanwhile, efforts to improve the professionalism of school principals by following supervision

Three-dimensional structures and elemental distributions of Stardust impact tracks using synchrotron microtomography and X-ray fluorescence analysis

Three-dimensional structures and elemental abundances of four impact tracks in silica aerogel keystones of Stardust samples from comet 81P/Wild 2 (bulbous track 67 and carrot-type tracks 46, 47, and 68) were examined non-destructively by synchrotron radiation-based microtomography and X-ray fluorescence analysis. Track features, such as lengths, volumes and width as a function of track depth, were obtained quantitatively by tomography. A bulbous portion was present near the track entrance even in carrot-type tracks. Each impact of a cometary dust particle results in the particle disaggregated into small pieces that were widely distributed on the track walls as well as at its terminal. Fe, S, Ca, Ni, and eight minor elements are concentrated in the bulbous portion of track 68 as well as in terminal grains. It was confirmed that bulbous portions and thin tracks were formed by disaggregation of very fine fragile materials and relatively coarse crystalline particles, respectively. The almost constant ratio of whole Fe mass to track volume indicates that the track volume is almost proportional to the impact kinetic energy. The size of the original impactor was estimated from the absolute Fe mass by assuming its Fe content (CI) and bulk density. Relations between the track sizes normalized by the impactor size and impact conditions are roughly consistent with those of previous hypervelocity impact experiments.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202