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1. GPA Patterns of Black Mechanical Engineering Students

   Manning, Jessica; Mobley, Catherine; Orr, Marisa; Brawner, Catherine; Brent, Rebecca; Tidwell, Michael L. (August 2022, Proceedings of the 2022 Annual Conference of the American Society for Engineering Education. https://peer.asee.org/41089)

   In recent years, research has associated grade point average (GPA) with a variety of student outcomes during their undergraduate careers. The studies link higher GPAs to students being more likely to graduate in their major, while lower GPAs have been linked to students switching majors or leaving the institution. Further research, which focuses on how Black female and male students remain successful in different engineering degrees, is necessary to identify the underlying elements contributing to their entrance into and exit from engineering disciplines. This quantitative examination of trends among the GPAs of Black women and men is part of a larger NSF-funded mixed-methods study that includes in-depth student interviews of Black students who persisted in and switched from ME. In this quantitative paper, we examine the GPA patterns of Black students in Mechanical Engineering (ME). Students who have ever enrolled in ME have four potential, mutually exclusive, outcomes: 1) they can persist for 12 semesters without graduating; 2) they can graduate in ME within 12 semesters; 3) they can switch to another major; or 4) they can leave school. In this research, we identify the most common GPA patterns associated with graduated ME students. We hypothesize a relationship between distinct GPA patterns and whether a student persists in ME, graduates in ME, switches away from ME, or leaves the institution altogether. This quantitative investigation uses the Multiple-Institution Database for Investigating Engineering Longitudinal Development (MIDFIELD) to collect the cumulative GPA of ME students at each term. We use a functional cluster analysis approach to group similar patterns. First, a function is fit to each student record. Then a cluster analysis is conducted on the function parameters to identify natural groupings in the data. Once students are grouped according to their GPA profile, we examine the other characteristics and outcomes of the group. We present a visual quantitative analysis of the patterns in the GPAs of Black women and men who enroll in ME. Clustering analysis suggests that first-time-in-college (FTIC) Black female students in ME who graduated have a higher proportion of students in the higher GPA clusters than the proportion of FTIC Black male students who graduated in ME. A higher proportion of the male student population is clustered in the lower GPA cluster groups as compared to women in the lower GPA cluster groups. A higher proportion of students who graduated are in the higher GPA clusters than the proportion of graduated students in the lower GPA clusters. 

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2. Hydrous wadsleyite crystal structure up to 32 GPa

   https://doi.org/10.2138/am-2022-8380  

   Wang, Fei; Thompson, Elizabeth C; Zhang, Dongzhou; Xu, Jingui; Alp, Ercan E; Jacobsen, Steven D (October 2023, American Mineralogist)

   Abstract Hydroxylation of wadsleyite, β-(Mg,Fe)2SiO4, is associated with divalent cation defects and well known to affect its physical properties. However, an atomic-scale understanding of the defect structure and hydrogen bonding at high pressures is needed to interpret the influence of water on the behavior of wadsleyite in the mantle transition zone. We have determined the pressure evolution of the wadsleyite crystal symmetry and structure, including all O∙∙∙O interatomic distances, up to 32 GPa using single-crystal X-ray diffraction on two well-characterized, Fe-bearing (Fo90) samples containing 0.25(4) and 2.0(2) wt% H2O. Both compositions undergo a pressure-dependent monoclinic distortion from orthorhombic symmetry above 9 GPa, with the less hydrous sample showing a larger increase in distortion at increased pressures due to the difference in compressibility of the split M3 site in the monoclinic setting arising from preferred vacancy ordering at the M3B site. Although hydrogen positions cannot be modeled from the X-ray diffraction data, the pressure evolution of the longer O1∙∙∙O4 distance in the structure characterizes the primary hydrogen bond length. We observe the hydrogen-bonded O1∙∙∙O4 distance shorten gradually from 3.080(1) Å at ambient pressure to about 2.90(1) Å at 25 GPa, being still much longer than is defined as strong hydrogen bonding (2.5–2.7 Å). Above 25 GPa and up to the maximum pressure of the experiment at 32.5 GPa, the hydrogen-bonded O1∙∙∙O4 distance decreases no further, despite the fact that previous spectroscopic studies have shown that the primary O-H stretching frequencies continuously drop into the regime of strong hydrogen bonding (<3200 cm–1) above ~15 GPa. We propose that the primary O1-H∙∙∙O4 hydrogen bond in wadsleyite becomes highly nonlinear at high pressures based on its deviation from frequency-distance correlations for linear hydrogen bonds. One possible explanation is that the hydrogen position shifts from being nearly on the long O1-O4 edge of the M3 site to a position more above O1 along the c-axis. 

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3. Litho-GPA: Gaussian Process Assurance for Lithography Hotspot Detection

   https://doi.org/10.23919/DATE.2019.8714960  

   Ye, Wei; Alawieh, Mohamed Baker; Li, Meng; Lin, Yibo; Pan, David Z. (March 2019, DATE)
4. Structural complexity in ramp-compressed sodium to 480 GPa

   https://doi.org/10.1038/s41467-022-29813-4  

   Polsin, Danae N.; Lazicki, Amy; Gong, Xuchen; Burns, Stephen J.; Coppari, Federica; Hansen, Linda E.; Henderson, Brian J.; Huff, Margaret F.; McMahon, Malcolm I.; Millot, Marius; et al (December 2022, Nature Communications)

   Abstract The properties of all materials at one atmosphere of pressure are controlled by the configurations of their valence electrons. At extreme pressures, neighboring atoms approach so close that core-electron orbitals overlap, and theory predicts the emergence of unusual quantum behavior. We ramp-compress monovalent elemental sodium, a prototypical metal at ambient conditions, to nearly 500 GPa (5 million atmospheres). The 7-fold increase of density brings the interatomic distance to 1.74 Å well within the initial 2.03 Å of the Na + ionic diameter, and squeezes the valence electrons into the interstitial voids suggesting the formation of an electride phase. The laser-driven compression results in pressure-driven melting and recrystallization in a billionth of a second. In situ x-ray diffraction reveals a series of unexpected phase transitions upon recrystallization, and optical reflectivity measurements show a precipitous decrease throughout the liquid and solid phases, where the liquid is predicted to have electronic localization. These data reveal the presence of a rich, temperature-driven polymorphism where core electron overlap is thought to stabilize the formation of peculiar electride states. 

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5. Ferromagnesian jeffbenite synthesized at 15 GPa and 1200 °C

   https://doi.org/10.2138/am-2021-7852  

   Smyth, Joseph R.; Wang, Fei; Alp, E. Ercan; Bell, Aaron S.; Posner, Esther S.; Jacobsen, Steven D. (March 2022, American Mineralogist)

   Abstract Single crystals of Al-free, ferromagnesian jeffbenite up to 200 µm in size have been synthesized at 15 GPa and 1200 °C in a 1200 tonne multi-anvil press from a starting composition in the forsteritefayalite-magnetite-water system. This phase has the approximate formula Mg2.62Fe0.872+Fe1.633+Si2.88O12 and is observed to coexist with a Ca-free clinopyroxene plus what appears to be quenched melt. The crystal structure has been refined from single-crystal X-ray diffraction data and is similar to that determined for natural Al-bearing jeffbenite, Mg3Al2Si3O12, reported from inclusions in superdeep diamonds. The structure is a tetragonal orthosilicate in space group I42d with a = 6.6449(4) Å, c = 18.4823(14) Å, and is structurally more closely related to zircon than to garnet. The T2 site is larger than T1, shares an edge with the M2 octahedron, and incorporates significant Fe3+. Because of the tetrahedral incorporation of trivalent cations, jeffbenite appears to be compositionally distinct from garnet. Previous speculations that the phase may only occur as a retrograde decompression product from bridgmanite are not supported by its direct synthesis under transition zone conditions. The phase has a calculated density of 3.93 g/cm3, which is indistinguishable from a garnet of comparable composition, and is a possible component in the mantle transition zone under oxidizing conditions or with Al-rich compositions. 

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