A5071745416- Vehicle emissions and performance
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Air Quality and Health Impacts
- Science Education and Pedagogy
- Outdoor and Experiential Education
- Atmospheric chemistry and aerosols
- Adventure Sports and Sensation Seeking
- Education and Critical Thinking Development
- Air Quality Monitoring and Forecasting
- Innovative Teaching and Learning Methods
- Molecular Spectroscopy and Structure
- Quantum, superfluid, helium dynamics
- Physical Education and Pedagogy
- Experimental Learning in Engineering
- Online and Blended Learning
- Spectroscopy and Laser Applications
- Diverse Educational Innovations Studies
- Educational Games and Gamification
- Winter Sports Injuries and Performance
- Catalytic Processes in Materials Science
- Online Learning and Analytics
- Mass Spectrometry Techniques and Applications
- Education and Technology Integration
- Science Education and Perceptions
The University of Texas at El Paso
2010-2024
California Air Resources Board
2007-2021
Médecins Sans Frontières
2021
California Maritime Academy
2015
West Virginia University
2009
General Atomics (United States)
2008
California Department of Fish and Wildlife
2008
University of California, Irvine
2006-2007
Environmental Molecular Sciences Laboratory
2006
University of Southern California
2006
The levels of four sets pollutants (heavy-metals, artificial radionuclides, petroleum components, and halogenated hydrocarbons), have been measured in U.S. coastal waters, using bivalves as sentinel organisms. strategies carrying out this programme are outlined the results from first year's work given. Varying degrees pollution waters indicated by elevated bivalves, which comprised certain species mussels oysters were collected at over one hundred localities.
This review provides a historical context for our understanding of the hydration shell surrounding halide ions and illustrates how cluster systems can be used, in combination with theory, to elucidate behavior water molecules direct contact anion. We discuss vibrational predissociation spectroscopy, carried out weakly bound argon atoms, has been employed deduce morphology small networks attached anions primary steps hydration. emphasize importance charge-transfer binary interaction, this...
There has been long-standing uncertainty about the number of water molecules in primary coordination environment OH − and F ions aqueous chemistry. We report vibrational spectra ·(H 2 O) n clusters interpret pattern stretching fundamentals with ab initio calculations. The cold complexes are obtained by first attaching weakly bound argon atoms to then monitoring photoinduced evaporation these when an infrared laser is tuned a resonance. small ( ≤ 3) display isolated, sharp feature near free...
Abstract. Environmental chamber ("smog chamber") experiments were conducted to investigate secondary organic aerosol (SOA) production from dilute emissions two medium-duty diesel vehicles (MDDVs) and three heavy-duty (HDDVs) under urban-like conditions. Some of the equipped with emission control aftertreatment devices, including particulate filters (DPFs), selective catalytic reduction (SCR) oxidation catalysts (DOCs). Experiments also performed different fuels (100% biodiesel low-, medium-...
Four heavy-duty and medium-duty diesel vehicles were tested in six different aftertreament configurations using a chassis dynamometer to characterize the occurrence of nucleation (the conversion exhaust gases particles upon dilution). The aftertreatment included four particulate filters two selective catalytic reduction (SCR) devices. All DPFs reduced emissions solid by several orders magnitude, but certain cases volatile mode could increase total particle number emissions. be predicted...
Emissions from four heavy-duty and medium-duty diesel vehicles were tested in six different aftertreatment configurations using a chassis dynamometer. The included particle filters (DPF) two prototype selective catalytic reduction (SCR) devices for NOx control. goal of the project was to fully characterize emissions various in-use meeting 2007 particulate matter (PM) standard United States California provide snapshot 2010 compliant vehicles. all worked as designed, realizing significant...
In total, 24 polycyclic aromatic hydrocarbons (PAHs) in both gas and particle phases 35 nitro-PAHs phase were analyzed the exhaust from heavy-duty diesel vehicles equipped with after-treatment for particulate matter (PM) NOX control. The test carried out using a chassis dynamometer under highway cruise, transient Urban Dynamometer Driving Schedule (UDDS), idle operation. efficiently abated more than 90% of total PAHs. Indeed, particle-bound PAHs reduced by >99%, gaseous removed at various...
To explore how a structured excess charge distribution affects the hydration of an anion, we report mid-IR, argon predissociation spectra for hydrated superoxide cluster anions, O2−⋅(H2O)n, 1⩽n⩽5. This size range was chosen to establish evolution structures through putative shell closing [Weber et al., Science 287, 2461 (2000)] at tetrahydrate. Whereas observed bonding motifs n⩽4 are those single water molecules and dimeric subclusters bound ion, pentahydrate spectrum displays strong bands...
We describe an ion source for the efficient preparation of cold ion-molecule complexes, X−⋅M. The method relies on condensation solvent molecules, M, onto argon-solvated ions, X−⋅Arm, where X−⋅Arm species are formed in a primary expansion and molecular partner, is interfaced to this flow hydrodynamic region by supersonic entrainment. This hybrid “supersonic afterglow” reactor provides clean synthetic approach both bare latter particularly useful since their structures can be characterized...
This study evaluated the UN-ECE Particle Measurement Programme (PMP) protocol for measurement of solid particle number emissions under laboratory and on-road conditions two passive diesel filters (DPF)–equipped medium heavy-heavy duty vehicles. The PMP were lower than European light-duty certification value (9.6 × 1011 #/mi) all standardized cycles, but exceeded this during some higher load driving conditions. measurements generally less variable those PM mass testing, had comparable or...
This study provides an evaluation of the nature sub-23-nm particles downstream European Particulate Measurement Programme (PMP) methodology, with prescribed cycles and on-road flow-of-traffic driving conditions. Particle number concentrations size distributions were measured using two PMP measurement systems running simultaneously. For this analysis, focus is on real-time results from multiple instruments. The revealed that a significant fraction both for all tested below 11 nm. sub-11-nm...
We present mid-IR argon predissociation spectra for a series of complexes, M-·H2O (M = CS2-, OCS-, SO2-, CH3NO2-, CH3CO2-, and NO2-), chosen to explore how changes in the triatomic binding site affect H-bonding configuration attached water molecule. With exception NO2-, calculated global minima on potential surfaces all complexes occur where both OH groups are anion. The observed spectra, other hand, fall into three distinct categories. Simple characteristic double ionic arrangement...
A new technique is introduced for the acquisition of size-selected neutral cluster spectra on basis argon-mediated, population-modulated electron attachment. This method demonstrated and used to obtain vibrational spectrum water hexamer precursor (H2O)6- ion. The mid-infrared species dominated by four intense features above 3400 cm-1, clearly indicating that significant structural rearrangements occur upon slow attachment form "magic" anion. Comparison with previous spectroscopic reports...
The reaction kinetics for gaseous hydroxyl radicals (OH) with deliquesced sodium chloride particles (NaCl(aq)) were investigated using a novel experimental approach. technique utilizes the exposure of substrate-deposited aerosol to reactive gases followed by chemical analysis computer-controlled scanning electron microscopy energy-dispersive X-rays (CCSEM/EDX) capability. Experiments performed at room temperature and atmospheric pressure NaCl in micron size range 70-80% RH OH concentrations...
This work evaluated the nitrogen oxide (NOx) emissions of 277 heavy-duty diesel vehicles (HDDVs) from three portable emission measurement system testing programs. HDDVs in these programs were properly maintained before testing, so malfunction indicator lamp (MIL) was not illuminated. NOx some significantly higher than certification standard even during hot operations where exhaust temperature ideal for selective catalytic reduction to reduce NOx. For engines certified 0.20 g/bhp-hr standard,...
The OH stretching bands associated with the ionic H-bond in Cl-·H2O complex are found to dramatically shift toward higher energy upon complexation carbon tetrachloride molecules a size selected photofragmentation study of Cl-·H2O·(CCl4)n, 1 ≤ n 5, clusters. large sequential shifts (80−100 cm-1/CCl4) addition first few effectively "tune" stretch v = level through Fermi resonance 2 intramolecular bending vibration. By fifth molecule, red-shift displayed by bare (577 cm-1 relative isolated...
Infrared spectra of I−⋅(CH3OH)n⋅Arm, n=1,2 clusters, obtained via argon and methanol predissociation, are interpreted with the aid ab initio calculations OH stretching fundamentals. The cold, argon-solvated clusters establish coexistence two isomeric forms n=2 cluster, asymmetric isomer displaying a dramatic (∼150 cm−1) red-shift relative to both symmetric n=1 complex. We trace this cooperative H-bonding which is only operative in form. At higher internal energies afforded by bare (i.e.,...
Argon predissociation spectroscopy is used together with ab initio electronic structure calculations to characterize the NO−⋅(H2O)n=1–3 clusters. In all cases, water molecules bind ion through single ionic H bonds. Two isomeric forms are assigned for n=1 species that differ according whether bond occurs N or O atom of core ion. While spectra dihydrate indicate formation an H-bonded dimer subcluster consistent four predicted isomers, their calculated vibrational too similar establish which...