Creative Commons CC BY: This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://www.creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).In a recent review of research on gendered performance disparities in undergraduate science, technology, engineering, and mathematics (STEM) courses, Eddy and Brownell (2016) describe a confused research landscape: Some courses favor men, some favor women, and some show little bias. Their review calls specifically for systematic measurement of performance gaps across an array of disciplines and institutions, all accounting for prior academic performance, in the hope that emergent patterns might inform our understanding of "the relative contributions of different factors to performance and/or persistence in STEM." In this study, we answer this call, analyzing data on more than a million student enrollments in hundreds of courses drawn from five research-intensive public universities in the Big Ten Academic Alliance.We find evidence of statistically significant, persistent gendered performance differences (GPDs) in some large, introductory courses, differences that are also materially significant. In particular, men earned relatively higher grades than women in biology, chemistry, physics, accounting, and economics lecture courses, even after accounting for the influence of some measures of prior academic achievements Significant gendered performance differences are signals of systemic inequity in higher education. Understanding of these inequities has been hampered by the local nature of prior studies; consistent measures of performance disparity across many disciplines and institutions have not been available. Here, we report the first wide-ranging, multi-institution measures of gendered performance difference, examining more than a million student enrollments in hundreds of courses at five universities. After controlling for factors that relate to academic performance using optimal matching, we identify patterns of gendered performance difference that are consistent across these universities. Biology, chemistry, physics, accounting, and economics lecture courses regularly exhibit gendered performance differences that are statistically and materially significant, whereas lab courses in the same subjects do not. These results reinforce the importance of broad investigation of performance disparities across higher education. They also help focus equity research on the structure and evaluative schemes of these lecture courses.

Graphene has been the subject of intense research in recent years due to its unique electrical, optical and mechanical properties. Furthermore, it is expected that quantum dots of graphene would make their way into devices due to their structure and composition which unify graphene and quantum dots properties. Graphene quantum dots (GQDs) are planar nano flakes with a few atomic layers thick and with a higher surface-to-volume ratio than spherical carbon dots (CDs) of the same size. We have developed a pulsed laser synthesis (PLS) method for the synthesis of GQDs that are soluble in water, measure 2–6 nm across, and are about 1–3 layers thick. They show strong intrinsic fluorescence in the visible region. The source of fluorescence can be attributed to various factors, such as: quantum confinement, zigzag edge structure, and surface defects. Confocal microscopy images of bacteria exposed to GQDs show their suitability as biomarkers and nano-probes in high contrast bioimaging.

6415of the most highly charged myoglobin charge states (observed for the AMP studies). While the reduced intensities of the higher charge states may simply reflect a shift in the entire distribution to lower charge state, the high attenuation rat@ lead us to believe that ion-neutral processes may also contribute. Indeed, studies by McLuckey et ai. have shown that ion-molecule reactions can preferentially attenuate higher charge states." It is believed that Coulombic forces result in the higher charge states being more reactive. Uncertainties in the reaction rates and thermodynamics of their reactions presently preclude unambiguous interpretation of our results.We believe that under our conditions, reaction with multiply protonated macroions could be a requirement for detectable charge inversion of singly charged anions (see Table I). A "one-step" multiproton transfer (reaction 1) could have substantially largerrates than a two-step sequential charge inversion (Le., an ion-ion reaction followed by an ion-molecule reaction). Although the first neutralization step is likely also to occur, we believe it is unlikely to contribute to the charge inversion process due to a rate-limiting reionization step. One might also expect the ionneutral process would have a collision cross section substantially lower than that of the initial ion-ion step. A single-step charge inversion process would explain both the high effciency for overall inversion and the requirement for multiple protonation of the positive ion reactant.The evidence presented for charge inversion in the reaction of singly charged anions with multiply charged macroions raises many questions for future ion-molecule and ion-ion reaction studies. We wonder about the roles of ion structure, energetics, and chemical equilibrium on these reactions. If we assume that the charge inversion occurs as a result of a single ion-ion encounter (reaction l), how rapidly do the two protons transfer and how might that transfer be influenced by the chemical nature and proximity of the charge sites? What role, if any, is played by associated solvent molecules and the bath gas? Further investigations are being initiated to address these issues.Nascent vibrational skate distributions of SO(X3Z-) have been measured by laser-induced fluorescence spectroscopy following the 193-nm photodissociations of SO,, SOCI,, and (CH3),S0 in the gas phase. All three of the distributions are found to be inverted, indicating strong dynamical effects in the photodissociation processes. A Franck-Condon/golden rule model is used to propose mechanisms to account for the experimental vibrational distributions.

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