103 research outputs found

    Instrument for Analysis of Organic Compounds on Other Planets

    Get PDF
    The goal of this project is to develop the Instrument for Solvent Extraction and Analysis of Extraterrestrial Bodies using In Situ Resources (ISEE). Specifically, ISEE will extract and characterize organic compounds from regolith which is found on the surface of other planets or asteroids. The techniques this instrument will use are supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC). ISEE aligns with NASA's goal to expand the frontiers of knowledge, capability, and opportunities in space in addition to supporting NASA's aim to search for life elsewhere by characterizing organic compounds. The outcome of this project will be conceptual designs of 2 components of the ISEE instrument as well as the completion of proof-of-concept extraction experiments to demonstrate the capabilities of SFE. The first conceptual design is a pressure vessel to be used for the extraction of the organic compounds from the regolith. This includes a comparison of different materials, geometry's, and a proposition of how to insert the regolith into the vessel. The second conceptual design identifies commercially available fluid pumps based on the requirements needed to generate supercritical CO2. The proof-of-concept extraction results show the percent mass lost during standard solvent extractions of regolith with organic compounds. This data will be compared to SFE results to demonstrate the capabilities of ISEE's approach

    X-ray absorption spectroscopy systematics at the tungsten L-edge

    Get PDF
    A series of mononuclear six-coordinate tungsten compounds spanning formal oxidation states from 0 to +VI, largely in a ligand environment of inert chloride and/or phosphine, has been interrogated by tungsten L-edge X-ray absorption spectroscopy. The L-edge spectra of this compound set, comprised of [W<sup>0</sup>(PMe<sub>3</sub>)<sub>6</sub>], [W<sup>II</sup>Cl<sub>2</sub>(PMePh<sub>2</sub>)<sub>4</sub>], [W<sup>III</sup>Cl<sub>2</sub>(dppe)<sub>2</sub>][PF<sub>6</sub>] (dppe = 1,2-bis(diphenylphosphino)ethane), [W<sup>IV</sup>Cl<sub>4</sub>(PMePh<sub>2</sub>)<sub>2</sub>], [W<sup>V</sup>(NPh)Cl<sub>3</sub>(PMe<sub>3</sub>)<sub>2</sub>], and [W<sup>VI</sup>Cl<sub>6</sub>] correlate with formal oxidation state and have usefulness as references for the interpretation of the L-edge spectra of tungsten compounds with redox-active ligands and ambiguous electronic structure descriptions. The utility of these spectra arises from the combined correlation of the estimated branching ratio (EBR) of the L<sub>3,2</sub>-edges and the L<sub>1</sub> rising-edge energy with metal Z<sub>eff</sub>, thereby permitting an assessment of effective metal oxidation state. An application of these reference spectra is illustrated by their use as backdrop for the L-edge X-ray absorption spectra of [W<sup>IV</sup>(mdt)<sub>2</sub>(CO)<sub>2</sub>] and [W<sup>IV</sup>(mdt)<sub>2</sub>(CN)<sub>2</sub>]<sup>2–</sup> (mdt<sup>2–</sup> = 1,2-dimethylethene-1,2-dithiolate), which shows that both compounds are effectively W<sup>IV</sup> species. Use of metal L-edge XAS to assess a compound of uncertain formulation requires: 1) Placement of that data within the context of spectra offered by unambiguous calibrant compounds, preferably with the same coordination number and similar metal ligand distances. Such spectra assist in defining upper and/or lower limits for metal Z<sub>eff</sub> in the species of interest; 2) Evaluation of that data in conjunction with information from other physical methods, especially ligand K-edge XAS; 3) Increased care in interpretation if strong π-acceptor ligands, particularly CO, or π-donor ligands are present. The electron-withdrawing/donating nature of these ligand types, combined with relatively short metal-ligand distances, exaggerate the difference between formal oxidation state and metal Z<sub>eff</sub> or, as in the case of [W<sup>IV</sup>(mdt)<sub>2</sub>(CO)<sub>2</sub>], add other subtlety by modulating the redox level of other ligands in the coordination sphere

    Infrared Absorption Investigations Confirm the Extraterrestrial Origin of Carbonado-Diamonds

    Full text link
    The first complete infrared FTIR absorption spectra for carbonado-diamond confirm the interstellar origin for the most enigmatic diamonds known as carbonado. All previous attempts failed to measure the absorption of carbonado-diamond in the most important IR-range of 1000-1300 cm-1 (10.00-7.69 micro-m.) because of silica inclusions. In our investigation, KBr pellets were made from crushed silica-free carbonado-diamond and thin sections were also prepared. The 100 to 1000 times brighter synchrotron infrared radiation permits a greater spatial resolution. Inclusions and pore spaces were avoided and/or sources of chemical contamination were removed. The FTIR spectra of carbonado-diamond mostly depict the presence of single nitrogen impurities, and hydrogen. The lack of identifiable nitrogen aggregates in the infrared spectra, the presence of features related to hydrocarbon stretch bonds, and the resemblance of the spectra to CVD and presolar diamonds indicate that carbonado-diamonds formed in a hydrogen-rich interstellar environment. This is consistent with carbonado-diamond being sintered and porous, with extremely reduced metals, metal alloys, carbides and nitrides, light carbon isotopes, surfaces with glassy melt-like patinas, deformation lamellae, and a complete absence of primary, terrestrial mineral inclusions. The 2.6-3.8 billion year old fragmented body was of asteroidal proportions

    Evolution of interstellar dust and stardust in the solar neighbourhood

    Full text link
    The abundance evolution of interstellar dust species originating from stellar sources and from condensation in molecular clouds in the local interstellar medium of the Milky Way is studied and the input of dust material to the Solar System is determined. A one-zone chemical evolution model of the Milky Way for the elemental composition of the disk combined with an evolution model for its interstellar dust component similar to that of Dwek (1998) is developed. The dust model considers dust-mass return from AGB stars as calculated from synthetic AGB models combined with models for dust condensation in stellar outflows. Supernova dust formation is included in a simple parameterized form which is gauged by observed abundances of presolar dust grains with supernova origin. For dust growth in the ISM a simple method is developed for coupling this with disk and dust evolution models. The time evolution of the abundance of the following dust species is followed in the model: silicate, carbon, silicon carbide, and iron dust from AGB stars and from SNe as well as silicate, carbon, and iron dust grown in molecular clouds. It is shown that the interstellar dust population is dominated by dust accreted in molecular clouds; most of the dust material entering the Solar System at its formation does not show isotopic abundance anomalies of the refractory elements, i.e., inconspicuous isotopic abundances do not point to a Solar System origin of dust grains. The observed abundance ratios of presolar dust grains formed in SN ejecta and in AGB star outflows requires that for the ejecta from SNe the fraction of refractory elements condensed into dust is 0.15 for carbon dust and is quite small (∼10−4\sim10^{-4}) for other dust species.Comment: 29 pages, 19 figure

    Interprofessional Education and Collaborative Practice (IPECP) in Post-COVID Healthcare Education and Practice Transformation Era – Discussion Paper. Joint Publication by InterprofessionalResearch.Global, American Interprofessional Health Collaborative & Canadian Interprofessional Health Collaborative

    Get PDF
    In the past two years the world has experienced unprecedented devastation, disruption, and death due to the COVID-19 global Pandemic. At the same time, the Pandemic acts as a transformation catalyst that accelerated the implementation and adoption of long overdue changes in healthcare education and practice, including telehealth and virtual learning.Interprofessional collaboration during the pandemic was able to foster healthcare transformation in several ways at the policy and legislative level, such as the fast-tracking of internationally trained professions. The role and use of digital technologies in healthcare education and practice have been extended and solidified by the pandemic. Macro-level policies acknowledging the importance ofpopulation health are key for future interprofessional collaboration of stakeholders to address inequalities. Similarly, interprofessional collaboration is key to addressing the proliferation of misinformation. Interprofessional education and collaborative practice (IPECP) can be effectively utilized to combat misinformation by increasing health literacy amongst health professions and the communities they serve.Despite IPECP being an integral component of promoting patient safety, and holistic, quality care, silos continue to exist. Furthermore, implementation of the Quintuple Aim (better health, better care, better value, better work experience, and better health equity), particularly through the lens of equity, remains elusive. Going forward, the integration and sustainability of IPECP are crucial and the experience of IPECP within the context of the COVID-19 pandemic should be reflected on, researched, and evaluated to inform future global healthcare systems and the workforce to provide and achieve the Quintuple Aim; the goal ofall in healthcare.As we are emerging out of the Pandemic, we have a unique opportunity to leverage on the lessons learned from the pandemic in fostering the healthcare transformation through innovation and IPECP. To capitalize on this opportunity and in a collaborative effort, the InterprofessionalResearch.Global (IPR.Global), the American Interprofessional Health Collaborative (AIHC), and the CanadianInterprofessional Health Collaborative (CIHC) have developed this e-book as a Discussion Paper to explore and discuss (from a global perspective) the impact and application of healthcare education and practice transformation on IPECP as we emerge from the COVID Pandemic with the goal to identify best practicesto integrate and sustain IPECP. We call the interprofessional educators, practitioners, leaders, scholars, and policy makers to utilize ‘Forward Thinking and Adaptability’ and ‘Sustainability and Growth’ in their IPECP approaches and strategies, to achieve Quintuple Aim. As learned during the Pandemic, working together – across professions, institutions, nationally, and globally – is essential in emerging stronger and in transforming our healthcare education and practice
    • …
    corecore