708 research outputs found

    Improving outcomes for underrepresented women in science: The Achieving Excellence in Mathematics, Engineering, and Science (AEMES) programs at Smith College

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    Created to support diverse students interested in the sciences, Smith College’s Achieving Excellence in Mathematics, Engineering, and Science (AEMES) programs have improved life science academic outcomes for women of color. Elements of Smith’s AEMES programs include leadership development, peer mentoring, and faculty-mentored research opportunities, all sharing the goals of building community, increasing academic engagement, and encouraging persistence for underrepresented students. Since launching AEMES, our students of color in the life sciences have shown significant gains in positive outcomes (introductory biology and chemistry course GPA; retention in life sciences majors), dissolving a previously observed gap in gateway course performance relative to majority students. We discuss potential explanations for these outcomes as well as our ongoing work to evaluate and foster programming efforts aimed at achieving further inclusive excellence in the sciences, especially given the lack of change in advanced life sciences research participation for students of color over time. With greater investments in programs that encourage access in undergraduate programs across the United States, such as Smith’s AEMES program, the next generation of scientists will become increasingly diverse, broadening the approaches and perspectives of our STEM talent and workforce

    Branched ketone biofuels as blending agents for Jet-A1 aviation kerosene

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    In this investigation a range of ketone biofuels produced from the alkylation of isoamyl alcohol and isobutanol were examined as potential blending agents with Jet A-1 aviation kerosene. The fuels were synthesized under solvent-free conditions using a Pd/C catalyst with K3PO4, previously reported for the alkylation of acetone, butanol, and ethanol (ABE) fermentation mixtures. Reasonable yields and selectivity were achieved for branched alkylation products with up to 61% produced from isoamyl alcohol and 64% from isobutanol. The key aviation fuel properties of the mixtures were tested unblended and in 50% and 20% blends with Jet A-1 aviation kerosene. The freezing points of the fuels were all found to be below the required −47 °C irrespective of blend or the temperature of the reaction. The energy density of the unblended fuels ranged between 30.4 and 41.36 MJ/kg depending on the temperature of the reaction and whether remaining alcohols were removed. While this is below the higher heating value (HHV) of the Jet A-1 used (45.69 MJ/kg), the energy densities of the 50% and 20% blends were more suitable with the isoamyl alcohol derived fuels having a maximum HHV of 44.31 MJ/kg at 50% blending and 44.99 MJ/kg at 20% blend with Jet A-1. The fuels derived from isoamyl alcohol produced above 140 °C were found to satisfy the flash point criterion (>38 °C) of the Jet A-1 specification, though the isobutanol derived fuels did not, producing fuels with flash points between 33 and 35 °C. The kinematic viscosities of the fuels were also tested at −20 °C. Unblended only a few of the fuels analyzed met the maximum viscosity requirement at −20 °C of 8 mm2 s–1, though this fuel property was improved substantially on blending with jet fuel. This work demonstrates that ketones produced from isoamyl alcohol through a simple alkylation have the potential to be used as blending agents with Jet A-1

    Deep red emitting heteroleptic Ir(III) complexes that incorporate unsymmetrical 4?quinoline carboxylic acid derived ligands

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    Six disubstituted ligands based upon 2-(2¢-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids have been synthesised, solvent-free, in one step from a range of commercially available isatin derivatives. These species behave as ancilllary chelating ligands for Ir(III) complexes of the form [Ir(C^N)2(N^N)]PF6 (where C^N = cyclometalating ligand; N^N = 2-(2¢-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids). An X-ray crystallographic study on one complex shows a distorted octahedral geometry wherein a cis-C,C and trans-N,N coordination mode is observed. DFT calculations predicted that changing the N^N ligand from 2,2¢-bipyridine to L1-6 should localise the LUMO on to the Ln ligand and that the complexes are predicted to display MLCT/LLCT character. All complexes displayed luminescence in the deep red part of the visible region (674-679 nm) and emit from triplet states, but with little apparent tuning as a function of L1-6. Further time-resolved transient absorption spectroscopy supports the participation of these triplet states to the excited state character

    471 Arrhythmia-free survival in early-persistent atrial fibrillation patients undergoing radiofrequency catheter ablation

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    Abstract Aims Despite advances in success rate of paroxysmal atrial fibrillation (PAF) ablation, outcomes of radiofrequency catheter ablation (RFCA) in patients with persistent AF are highly variable. Early persistent AF (EPsAF) is defined as AF that is sustained beyond 7 days but is less than 3 months in duration. Arrhythmia-free survival data after RFCA in this specific population are still limited. We sought to report the outcomes of RFCA in the subgroup of patients with EPsAF, compared to those with PAF and with 'late' persistent AF (LPsAF) lasting between 3 and 12 months. Methods and results Data from 1143 consecutive AF patients receiving their first RFCA were prospectively collected. Patients with EPsAF (n = 190) were compared with PAF (n = 531) and LPsAF (n = 422) patients. All patients received pulmonary vein antrum isolation + posterior wall and sustained non-pulmonary vein (PV) trigger ablation. Non-sustained non-PV triggers were ablated based on operator discretion. Non-PV triggers were defined as sites of firing leading to sustained (>30 s) or non-sustained arrhythmias (<30 s, including premature atrial contractions ≥10 beats/min) with earliest activation outside the PVs. Mean age of the population was 64 ± 11 years. Female patients were more in PAF group (39%) compared to EPsAF (26%) and LPsAF (28%) (P < 0.001). There was no difference in other clinical characteristics among populations. Non-PV triggers were detected more in EPsAF [127 (66.8%)], and LPsAF [296 (70.1%)] patients compared to PAF [185 (34.8%)] (P < 0.001).One-year arrhythmia-free survival rate after a single procedure was 75.0% (398), 74.2% (141), and 64.5% (272) in PAF, EPsAF, and LPsAF, respectively. Success rate was significantly higher in PAF {[HR: 0.67 (0.53, 0.84), P = 0.001] and EPsAF [HR: 0.67 (0.49, 0.93)], P = 0.015} compared to LPsAF. Conclusions In patients with EPsAF, RFCA may result in significantly better freedom from atrial arrhythmias, compared to LPsAF. In this cohort, ablation might be reasonable as first line approach to improve outcomes and prevent AF progression

    Dual visible/NIR emission from organometallic iridium(III) complexes

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    A series of four substituted benzo[g]quinoxaline species have been synthesised and utilised as cyclometalating ligands for iridium(III). The ligands (L1-L4) were synthesised and isolated in good yield following the condensation of 2,3-diaminonaphthalene with benzil and three of its derivatives. The substituent modulated electronic properties of L1-L4 were dominated by intraligand π−π* transitions, with the fluorescence profile demonstrating vibronic features attributed to the highly conjugated nature of the chromophore. Iridium(III) complexes of the form [Ir(L)2(bipy)]PF6 were synthesised from L1-L4 in two steps. The electronic properties of the complexes reveal absorption in the UV-vis. region with spin forbidden metal-to-ligand charge transfer (MLCT) transitions possibly contributing at longer wavelengths to ca. 600 nm. Steady state luminescence (aerated, room temperature) on solutions of the complexes showed dual emissive properties in the visible and near-infra red (NIR) regions. Firstly, a vibronically structured emission in the visible region (ca. 525 nm) was attributed to ligand centred fluorescence (lifetime < 10 ns). Secondly, a broad emission peak in the NIR (ca. 950 nm) which extended to around 1200 nm was observed with corresponding lifetimes of 116–162 ns, indicative of triplet excited state emission

    Water soluble, cyclometalated Pt(II)–Ln(III) conjugates towards novel bimodal imaging agents

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    Facile conjugation of a luminescent cyclometalated PtII complex with a DO3A-derived GdIII moiety yields a hybrid species with visible luminescence and enhanced relaxivity
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