A5062445438- Astrophysics and Star Formation Studies
- Advanced Chemical Physics Studies
- Astro and Planetary Science
- Atmospheric Ozone and Climate
- Molecular Spectroscopy and Structure
- Planetary Science and Exploration
- Space Exploration and Technology
- Archaeology and Historical Studies
- Atmospheric chemistry and aerosols
- High-pressure geophysics and materials
- Isotope Analysis in Ecology
- Ocular Surface and Contact Lens
- Ancient Egypt and Archaeology
- Space Science and Extraterrestrial Life
- Atomic and Molecular Physics
- Historical Astronomy and Related Studies
- Distributed systems and fault tolerance
- Intraocular Surgery and Lenses
- Solar and Space Plasma Dynamics
- Origins and Evolution of Life
- Free Radicals and Antioxidants
- Ancient Near East History
- Spacecraft and Cryogenic Technologies
- Historical, Religious, and Philosophical Studies
- Catalytic Processes in Materials Science
Environment and Climate Change Canada
2025
Health Affairs
2022-2024
University of Central Florida
2018-2024
Froedtert Hospital
2023
Jet Propulsion Laboratory
2021
Georgia Institute of Technology
2013-2019
University of Hawaiʻi at Mānoa
2004-2014
NASA Astrobiology Institute
2010-2014
University of Hawaii System
2010-2014
Mayo Clinic
2012
We have investigated the synthesis of simplest amino acid, glycine, by Galactic cosmic-ray particles in extraterrestrial ices. Laboratory experiments combined with electronic structure calculations showed that a methylamine molecule [CH3NH2(X1A')] can be dissociated through interaction energetic electrons track particle to form atomic hydrogen and radicals CH2NH2(X2A') CH3NH(X2A'). Hydrogen atoms sufficient kinetic energy could overcome entrance barrier add carbon dioxide [CO2(X1Σ)],...
Binary mixtures of methanol (CH3OH) and carbon monoxide (CO) ices were irradiated at 10 K with energetic electrons to mimic the energy transfer processes that occur in track trajectories MeV cosmic-ray particles. The formation glycolaldehyde (HCOCH2OH) was established through appearance new bands infrared spectrum 1757, 1700, 1690, 1367, 1267, 1067 cm-1. A second C2H4O2 isomer, methyl formate (HCOOCH3), also identified by absorptions appearing 1718, 1159, 914 Mass spectrometer signals during...
Pure methane ices (CH4) were irradiated at 10 K with energetic electrons to mimic the energy transfer processes that occur in track of trajectories MeV cosmic-ray particles. The experiments monitored via an FTIR spectrometer (solid state) and a quadrupole mass (gas phase). Combined electronic structure calculations, this paper focuses on identification CHx (x = 1-4) C2Hx 2-6) species also investigates their formation pathways quantitatively. primary reaction step is determined be cleavage...
Pure ices of amorphous methanol, CH3OH(X1A'), were irradiated at 11 K by 5 keV electrons 100 nA for 1 hr. These energetic simulate electronic energy transfer processes that occur as interstellar ices, comets, and icy solar system bodies are subjected to irradiation from MeV ions secondary produced in this process. The results analyzed quantitatively via absorption-reflection-absorption Fourier transform infrared (FTIR) spectroscopy, with the identification new species aided high-level...
Formamide, H2NCHO, represents the simplest molecule containing peptide bond. Consequently, formamide is of high interest as it considered an important precursor in abiotic synthesis amino acids, and thus significant to further prebiotic chemistry, more suitable environments. Previous experiments have demonstrated that formed under extreme conditions similar throughout interstellar medium via photolysis energetic processing ultracold solar system ices with high-energy protons; however, no...
The formation of the cyclic carbon trioxide isomer, CO3(X 1A1), in carbon-dioxide-rich extraterrestrial ices and atmospheres Earth Mars were investigated experimentally theoretically. Carbon dioxide deposited at 10 K onto a silver (111) single crystal irradiated with 5 keV electrons. Upon completion electron bombardment, samples kept then annealed to 293 release reactants newly formed molecules into gas phase. experiment was monitored via Fourier transform infrared spectrometer...
The synthetic routes to form acetaldehyde [CH3CHO(X1A')] in extraterrestrial ices were investigated experimentally a contamination-free ultrahigh vacuum scattering machine. Binary ice mixtures of carbon monoxide [CO(X1Σ+)] and methane [CH4(X1A1)] condensed at 10 K onto silver monocrystal irradiated with 5 keV electrons mimic the electronic energy transfer processes initiated by MeV cosmic-ray particle-induced δ-electrons "ultratrack" ion trajectories; monoxide-methane served as model...
Mixtures of water (H2O) and carbon monoxide (CO) ices were irradiated at 10 K with energetic electrons to simulate the energy transfer processes that occur in track galactic cosmic-ray particles penetrating interstellar ices. We identified formic acid (HCOOH) through new absorption bands infrared spectra 1690 1224 cm−1 (5.92 8.17 μm, respectively). During subsequent warm-up samples, is evident from mass spectrometer signal mass-to-charge ratio, m/z = 46 (HCOOH+) as ice sublimates. The...
Laboratory experiments were conducted to unravel synthetic routes form three C2H4O isomers—acetaldehyde (CH3CHO), ethylene oxide (c-C2H4O), and vinyl alcohol (CH2CHOH)—in extraterrestrial ices via electronic energy transfer processes initiated by electrons in the track of MeV ion trajectories. Here we present results electron irradiation on a 2 : 1 mixture carbon dioxide (CO2) (C2H4). Our studies suggest that suprathermal oxygen atoms can add carbon-carbon π bond an molecule initially...
Binary ice mixtures of methane (CH4) and carbon dioxide (CO 2) ices were irradiated at 12 K with energetic electrons to mimic the energy transfer processes that occur in track trajectories MeV cosmic-ray particles. The formation trans-acetic acid (CH3COOH) was established through appearance new bands infrared spectrum 1780, 1195, 1160, 1051, 957 cm-1; two dimeric forms acetic assigned via absorptions 1757 1723 cm-1 . During warm-up sample, mass spectrometer recorded peaks m/z values 60 45...
Valvular disease is estimated to account for as many 20% of cardiac surgical procedures performed in the United States. It may be congenital origin or secondary another process. One anomaly, bicuspid aortic valve, associated with increased incidence stenosis, regurgitation, endocarditis, and aneurysmal dilatation aorta. A valve has two cusps instead normal three; resultant fusion poor excursion leaflets lead presence which signaled by dephasing jets on magnetic resonance (MR) images. Surgery...
The formation of ozone (O3) in neat oxygen ices was investigated experimentally a surface-scattering machine. At 11 K, solid irradiated with energetic electrons; the chemical modification target followed on-line and situ via Fourier transform infrared spectroscopy (FTIR; state) quadrupole mass spectrometry (QMS; gas phase). dominant product identified molecule bent, C2v symmetric structure, O3(X1A1); cyclic D3h isomer not observed. associated van der Waals complexes [O3...O] [O3...O3] could...
A series of ice mixtures containing carbon monoxide (CO), dioxide (CO(2)), and molecular oxygen (O(2)) with varying carbon-to-oxygen ratios from 1 : 1.5 to 4 were irradiated at 10 K energetic electrons derive formation mechanisms destruction pathways trioxide (CO(3)) in extraterrestrial, low temperature ices. Reactants products analyzed on line situ via absorption-reflection-absorption FTIR spectroscopy the solid state, while gas phase was sampled by a quadrupole mass spectrometer (QMS)....
We present a joint crossed molecular beam and kinetics investigation combined with electronic structure statistical calculations on the reaction of ground-state cyano radical, CN(X2Σ+), 1,3-butadiene molecule, H2CCHCHCH2(X1Ag), its partially deuterated counterparts, H2CCDCDCH2(X1Ag) D2CCHCHCD2(X1Ag). The studies indicate that proceeds via long-lived C5H6N complex, yielding C5H5N isomer(s) plus atomic hydrogen under single collision conditions as nascent product(s). Experiments 1,3-butadienes...
Pure ethane ices (C2H6) were irradiated at 10, 30, and 50 K under contamination-free, ultrahigh vacuum conditions with energetic electrons generated in the track of galactic cosmic-ray (GCR) particles to simulate interaction GCRs outer solar system. The chemical processing samples was monitored by a Fourier transform infrared spectrometer quadrupole mass during irradiation phase subsequent warm-up phases on line situ order extract qualitative (products) quantitative (rate constants yields)...
We discuss the novel design of a sensitive, normal-Raman spectrometer interfaced to an ultra-high vacuum chamber (5 × 10–11 Torr) utilized investigate interaction ionizing radiation with low temperature ices relevant solar system and interstellar medium. The is based on pulsed Nd:YAG laser which takes advantage gating techniques isolate scattered Raman signal from competing fluorescence signal. setup incorporates innovations achieve maximum sensitivity without detectable heating sample. Thin...
The formation of nitrous oxide, N2O(X1Σ+), in interstellar space and ices on Pluto Triton has been experimentally investigated. A molecular nitrogen (N2) carbon dioxide (CO2) ice mixture was irradiated at 10 K with 5 keV electrons to simulate the electronic interaction effects Galactic cosmic-ray bombardment extraterrestrial samples over a time × 106 yr. By monitoring experiment Fourier transform infrared spectrometer line situ, temporal evolution 2235 cm-1 absorption band oxide found follow...
Binary ice mixtures of two carbon monoxide isotopomers, 13C16O and 12C18O, were subjected at 10 K to energetic electrons investigate the interaction ionizing radiation with extraterrestrial, bearing ices. The chemical modifications monitored on line in situ via absorption–reflection–absorption Fourier transform infrared spectroscopy as well gas-phase a quadrupole mass spectrometer. Detected products include newly formed isotopomers (12C16O 13C18O), dioxide (12C16O2, 12C18O16O, 12C18O2,...
Alkylbenzene sulfonates (ABS) are surfactants widely used in residential and commercial products. To support the environmental risk assessment of these compounds, acute toxicity three ABS, linear (n-ABS), branched (BABS), alkyl phenoxybenzene (APBS), was evaluated using six aquatic organisms from different trophic levels (algae, daphnid, amphipod, mussel, snail, fish). This approach allowed direct comparisons among species to provide insights into sensitivity surfactants, compounds...
Multimodal microscopy that combines complementary nanoscale imaging techniques is critical for extracting comprehensive chemical, structural, and functional information, particularly heterogeneous samples. X-ray can achieve high-resolution of bulk materials with magnetic, electronic, bond orientation contrast, while electron provides atomic-scale spatial resolution quantitative elemental composition. Here, we combine x-ray ptychography scanning transmission spectromicroscopy...
The formation of carbon dioxide from the processing monoxide (CO) and molecular oxygen (18O2) via radiolysis is studied within context its in interstellar ices quiescent clouds. With help isotopic labeling, we were able to ''trace'' atoms provide mechanistical information on how decomposed, formed ices. Here, quantify production 18O3, O18O2, 18OO18O, C18O, CO2, 18OCO, C18O2. In contrast experiments using ultraviolet irradiation, find that upon exposure energetic electrons, isolated molecules...