103 research outputs found
Instrument for Analysis of Organic Compounds on Other Planets
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
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Transmission electron microscopy study in-situ of radiation-induced defects in copper at elevated temperatures
Neutrons and high-energy ions incident upon a solid can initiate a displacement collision cascade of lattice atoms resulting in localized regions within the solid containing a high concentration of interstitial and vacancy point defects. These point defects can collapse into various types of dislocation loops and stacking fault tetrahedra (SFT) large enough that their lattice strain fields are visible under diffraction-contrast imaging using a Transmission Electron Microscope (TEM). The basic mechanisms driving the collapse of point defects produced in collision cascades is investigated in situ with TEM for fcc-Cu irradiated with heavy (100 keV Kr) ions at elevated temperature. The isothermal stability of these clusters is also examined in situ. Areal defect yields were observed to decrease abruptly for temperatures greater than 300 C. This decrease in defect yield is attributed to a proportional decrease in the probability of collapse of point defects into clusters. The evolution of the defect density under isothermal conditions appears to be influenced by three different rate processes active in the decline of the total defect density. These rate constants can be attributed to differences in the stability of various types of defect clusters and to different loss mechanisms. Based upon observed stabilities, estimations for the average binding enthalpies of vacancies to SFT are calculated for copper
X-ray absorption spectroscopy systematics at the tungsten L-edge
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
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
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 () for other dust species.Comment: 29 pages, 19 figure
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Photoionization of alkali and alkaline earth atoms: Na and Mg
Determinations of the photoionization cross sections of ground state magnesium atoms and excited state sodium atoms have been made over a wide wavelength range. The ground state measurement in magnesium was performed using synchrotron radiation from the uv ring at the National Synchrotron Light Source. Several autoionizing resonances were observed. The photoionization cross section of excited sodium atoms was determined by irradiating laser-produced Na(3p) with synchrotron light. In both cases, agreement with theory is excellent
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
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
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