A novel analytical method is presented whereby Direct Analysis in Real Time-Mass Spectrometry (DART-MS) is applied to the study of gas-surface heterogeneous reactions. To illustrate the capabilities of the approach, the kinetics of a well-studied reaction of surface-bound polycyclic aromatic hydrocarbons with ozone are presented. Specifically, using helium as the reagent gas and with the DART heater temperature of 500 °C, nanogram quantities of benzo[e]pyrene (BeP) deposited on the outside of glass melting point capillary tubes were analyzed in positive ion mode with a limit of detection of 40 pg. Using bis(2-ethylhexyl) sebacate as an internal standard, the kinetics of the ozone-BeP reaction were assessed by determining the surface-bound BeP decays, after oxidation in an off-line reaction cell. The reaction is demonstrated to follow the Langmuir-Hinshelwood mechanism, known to prevail for heterogeneous reactions of this type. In addition, a wide array of oxygenated, condensed-phase products has been observed. The present work demonstrates the capability of the DART-MS technique to investigate the heterogeneous chemistry taking place on a wide range of surfaces, such as those that form in both outdoor and indoor environments.
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http://dx.doi.org/10.1021/ac504722z | DOI Listing |
J Math Biol
January 2025
Department of Integrative Biology, Oklahoma State University, Stillwater, OK, 74078, USA.
In the past several decades, much attention has been focused on the effects of dispersal on total populations of species. In Zhang (EL 20:1118-1128, 2017), a rigorous biological experiment was performed to confirm the mathematical conclusion: Dispersal tends to enhance populations under a suitable hypothesis. In addition, mathematical models keeping track of resource dynamics in population growth were also proposed in Zhang (EL 20:1118-1128, 2017) to understand this remarkable phenomenon.
View Article and Find Full Text PDFUltramicroscopy
January 2025
Mechanical Engineering, University of Michigan, USA.
The objective of this work was to explore the capabilities of a field emission gun scanning electron microscope (FEG-SEM) equipped with a transmission scanning electron detector (TSEM) and energy dispersive spectroscopy (EDS) to identify nanoscale chemical heterogeneities in a gas atomization reaction synthesis (GARS) steel sample. The results of this analysis were compared to the same study conducted with scanning transmission electron microscopy (STEM) with EDS mapping. TSEM-EDS was performed using the standard spectral analysis approach, i.
View Article and Find Full Text PDFFront Biosci (Landmark Ed)
January 2025
Graduate School of Life and Environmental Sciences, Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi, 400-8510 Kofu, Japan.
Background: Sperm represent a heterogeneous population crucial for male reproductive success. Additionally, sperm undergo dynamic changes during maturation and capacitation. Despite these well-established processes, the complex nature of sperm heterogeneity and membrane dynamics remains elusive.
View Article and Find Full Text PDFPharmaceutics
January 2025
Laboratory of Nuclear Medicine (LIM-43), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo 05403-911, SP, Brazil.
Background/objectives: Dithiocarbazates (DTCs) and their metal complexes have been studied regarding their property as anticancer activities. In this work, using S-benzyl-5-hydroxy-3-methyl-5-phenyl-4,5-dihydro-1H-pirazol-1-carbodithionate (Hbdtc), we prepared [ReO(bdtc)(Hbdtc)] and [[Tc]TcO(bdtc)(Hbdtc)] complexes for tumor uptake and animal biodistribution studies.
Methods: Re complex was prepared by a reaction of H2bdtc and (NBu)[ReOCl], the final product was characterized by IR, H NMR, CHN, and MS-ESI.
Molecules
January 2025
Department of Polymer Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Skłodowska University, Gliniana 33 Street, 20-614 Lublin, Poland.
The properties of starch graft poly(cinnamyl methacrylate) copolymers were presented. The "grafting from" method and different ratios of starch to methacrylic monomer were used. The copolymers with the maximum grafting percent (G: 55.
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