Forest fires are major contributors of reactive gas- and particle-phase organic compounds to the atmosphere. We used offline high-resolution tandem mass spectrometry to perform a molecular-level ...speciation of gas- and particle-phase compounds sampled via aircraft from an evolving boreal forest fire smoke plume in Saskatchewan, Canada. We observed diverse multifunctional compounds containing oxygen, nitrogen, and sulfur (CHONS), whose structures, formation, and impacts are understudied. The dilution-corrected absolute ion abundance of particle-phase CHONS compounds increased with plume age by a factor of 6.4 over the first 4 h of downwind transport, and their relative contribution to the observed functionalized organic aerosol (OA) mixture increased from 19 % to 40 %. The dilution-corrected absolute ion abundance of particle-phase compounds with sulfide functional groups increased by a factor of 13 with plume age, and their relative contribution to observed OA increased from 4 % to 40 %. Sulfides were present in up to 75 % of CHONS compounds and the increases in sulfides were accompanied by increases in ring-bound nitrogen; both increased together with CHONS prevalence. A complex mixture of intermediate- and semi-volatile gas-phase organic sulfur species was observed in emissions from the fire and depleted downwind, representing potential precursors to particle-phase CHONS compounds. These results demonstrate CHONS formation from nitrogen- and oxygen-containing biomass burning emissions in the presence of reduced sulfur species. In addition, they highlight chemical pathways that may also be relevant in situations with elevated emissions of nitrogen- and sulfur-containing organic compounds from residential biomass burning and fossil fuel use (e.g., coal), respectively.
•Our integrated sampling-to-analysis system measures trace (sub-ppt) gas-phase organic compounds.•Holistic optimization of the entire adsorbent tube life cycle is necessary to achieve a high level of ...performance.•Careful preparation and handling extends analytical capabilities across a wide range of volatility and functionality.•These developments enable routine offline collection and detection from chamber, field, or aircraft studies.•The flexible integrated system platform seamlessly couples with multiple analytically powerful detectors.
Gas-phase organic compounds across a range of volatilities, including volatile organic compounds (VOCs), are key components of outdoor air, indoor spaces, and a variety of other anthropogenic and biogenic systems. The collection of offline samples on adsorbent-packed tubes for analysis on laboratory instrumentation has been in use for decades, but with limited sensitivities and compound coverage. We present and evaluate our integrated sampling-to-analysis system that enables offline detailed chemical characterization of multi-faceted organic mixtures at trace concentrations. Its capabilities extend across a diverse variety of VOCs with different molecular features, as well as intermediate and semivolatile organic compounds (I/SVOCs). Samples can be collected manually or via automated devices that have been applied in chamber, field, and aircraft platforms. The laboratory instrumentation can be coupled to both a high resolution mass spectrometer (MS) and a traditional quadrupole MS, though performance metrics presented in this study are determined via the traditional MS. We demonstrate capabilities for detailed chemical characterization and routine performance for a wide range of compound functionalities at sub-part per trillion (ppt) concentrations, and as low as <100 parts per quadrillion (ppq), yielding 3300 observed unique compound peaks in a single indoor air sample. These limits of detection and compound coverage were accomplished through a holistic optimization of the entire system and lifecycle of adsorbent tubes. We present our best practices for all aspects of tube production, handling, sampling, and analysis, and an examination of commercially-available materials and our custom adsorbent tubes using a diverse mix of VOC, IVOC, and SVOC standards, including difficult to measure analytes across a range of polarities and functionalities. In many aspects, the commercially-available materials and tube conditioners tested were insufficient for achieving low-ppt measurements.
We present a nanomechanical device, operating as a reprogrammable logic gate, and performing fundamental logic functions such as AND/OR and NAND/NOR. The logic function can be programmed (e.g., from ...AND to OR) dynamically, by adjusting the resonator’s operating parameters. The device can access one of two stable steady states, according to a specific logic function; this operation is mediated by the noise floor which can be directly adjusted, or dynamically “tuned” via an adjustment of the underlying nonlinearity of the resonator, i.e., it is not necessary to have direct control over the noise floor. The demonstration of this reprogrammable nanomechanical logic gate affords a path to the practical realization of a new generation of mechanical computers.
Unsaturated triglycerides found in food and skin oils are reactive in ambient air. However, the chemical fate of such compounds has not been well characterized in genuine indoor environments. Here, ...we monitored the aging of oil coatings on glass surfaces over a range of environmental conditions, using mass spectrometry, nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) techniques. Upon room air exposure (up to 17 ppb ozone), the characteristic ozonolysis products, secondary ozonides, were observed on surfaces near the cooking area of a commercial kitchen, along with condensed-phase aldehydes. In an office setting, ozonolysis is also the dominant degradation pathway for oil films exposed to air. However, for indoor enclosed spaces such as drawers, the depleted air flow makes lipid autoxidation more favorable after an induction period of a few days. Forming hydroperoxides as the major primary products, this radical-mediated peroxidation behavior is accelerated by indoor direct sunlight, but the initiation step in dark settings is still unclear. These results are in accord with radical measurements, indicating that indoor photooxidation facilitates radical formation on surfaces. Overall, many intermediate and end products observed are reactive oxygen species (ROS) that may induce oxidative stress in human bodies. Given that these species can be widely found on both food and household surfaces, their toxicological properties are worth further attention.
Enzymes are commonly used in food processing and in the production of food ingredients. Enzymes traditionally isolated from culturable microorganisms, plants, and mammalian tissues are often not ...well-adapted to the conditions used in modern food production methods. The use of recombinant DNA technology has made it possible to manufacture novel enzymes suitable for specific food-processing conditions. Such enzymes may be discovered by screening microorganisms sampled from diverse environments or developed by modification of known enzymes using modern methods of protein engineering or molecular evolution. As a result, several important food-processing enzymes such as amylases and lipases with properties tailored to particular food applications have become available. Another important achievement is improvement of microbial production strains. For example, several microbial strains recently developed for enzyme production have been engineered to increase enzyme yield by deleting native genes encoding extracellular proteases. Moreover, certain fungal production strains have been modified to reduce or eliminate their potential for production of toxic secondary metabolites. In this article, we discuss the safety of microorganisms used as hosts for enzyme-encoding genes, the construction of recombinant production strains, and methods of improving enzyme properties. We also briefly describe the manufacture and safety assessment of enzyme preparations and summarize options for submitting information on enzyme preparations to the US Food and Drug Administration.
Aerosol phase state is critical for quantifying aerosol effects on climate and air quality. However, significant challenges remain in our ability to predict and quantify phase state during its ...evolution in the atmosphere. Herein, we demonstrate that aerosol phase (liquid, semisolid, solid) exhibits a diel cycle in a mixed forest environment, oscillating between a viscous, semisolid phase state at night and liquid phase state with phase separation during the day. The viscous nighttime particles existed despite higher relative humidity and were independently confirmed by bounce factor measurements and atomic force microscopy. High-resolution mass spectrometry shows the more viscous phase state at night is impacted by the formation of terpene-derived and higher molecular weight secondary organic aerosol (SOA) and smaller inorganic sulfate mass fractions. Larger daytime particulate sulfate mass fractions, as well as a predominance of lower molecular weight isoprene-derived SOA, lead to the liquid state of the daytime particles and phase separation after greater uptake of liquid water, despite the lower daytime relative humidity. The observed diel cycle of aerosol phase should provoke rethinking of the SOA atmospheric lifecycle, as it suggests diurnal variability in gas–particle partitioning and mixing time scales, which influence aerosol multiphase chemistry, lifetime, and climate impacts.
•New routine capabilities to speciate complex gas-phase organic mixtures in air.•Dual MS setup combines hard electron ionization and soft chemical ionization.•High-resolution MS coupled to our ...integrated sampling-to-analysis system.•Characterizes complex mixtures of both primary and functionalized compounds.•Tandem mass spectrometry (MS/MS) enables isomer structural characterization.
Complex airborne mixtures of organic compounds can contain 10,000′s of diverse compounds at trace concentrations. Here, we incorporate high-resolution mass spectrometry into our integrated offline sampling-to-analysis measurement system for routine molecular-level speciation of complex mixtures in gas- or particle-phase samples with detection limits of 2–20 pg L−1 (i.e. 0.2–1.9 ppt in 6 L samples). Analytes desorbed from custom adsorbent tubes (or filter extracts) were separated via gas chromatography (GC) and simultaneously analyzed by an electron ionization quadrupole mass spectrometer (EI-MS), and by atmospheric pressure chemical ionization (APCI) combined with a high-resolution quadrupole time-of-flight mass spectrometer (Q-TOF) with a resolution of 25,000–40,000 M/ΔM in HR-TOF and MS/MS modes. We demonstrated our system with simple standards, a Macondo crude oil standard as a reference for complex mixtures of common airborne compounds, and ambient samples using GC-TOF and GC–MS/MS. We speciated complex mixtures at mass accuracy error (i.e. mass tolerance) down to 8 ± 2 ppm (e.g. resolving analytes of mass 270.000 u with 0.003 u accuracy) using a targeted approach with 3000 molecular formulas, including hydrocarbons and functionalized analytes containing oxygen, sulfur, nitrogen, or phosphorous. This extended from compounds with 10 to 32 carbon atoms and up to 16 hydrocarbon formulas per carbon number, and a similar range for functionalized compound classes. We also demonstrated our MS/MS capabilities to differentiate structural isomers and determine the presence of specific functional groups; and our direct-TOF capability, which bypasses high-temperature chromatographic separation to preserve functionalized analytes.
Interstitial lung disease (ILD) is a frequent extra-articular manifestation of RA associated with increased mortality. High-resolution CT (HRCT) is used for diagnosis and follow-up, but its accuracy ...is counterbalanced by high costs and radiological risk. In the presence of ILD, lung US (LUS) detects vertical artefacts called B-lines. The aims of the present study were to evaluate the accuracy of LUS in the diagnosis of ILD in RA and to validate the use of a pocket-size US device (PS-USD) as a screening tool.
LUS was performed with standard equipment by a trained physician through longitudinal scans following anatomical lines: 72 segments were considered (28 anteriorly and 44 posteriorly) and B-lines were counted in each segment. A B-lines score >10 identified a positive examination (presence of ILD). A second LUS session for positive/negative judgment was performed by a short-trained physician using a PS-USD.
Thirty-nine patients were studied. The sensitivity and specificity of standard LUS vs HRCT were 92% and 56%, respectively. The B-line score was significantly correlated with HRCT score (r = 0.806). A total of 29 patients were studied with a PS-USD. Sensitivity and specificity for PS-USD vs HRCT were 89% and 50%.
The sensitivity of LUS in the detection of ILD supports its use as a screening test for ILD in RA patients, even in the ambulatory setting with a PS-USD. The strong correlation between echographic and HRCT scores indicates LUS is a valid tool for grading and follow-up of ILD.
Exposure to ambient fine particulate matter (PM2.5) is associated with millions of premature deaths annually. Oxidative stress through overproduction of reactive oxygen species (ROS) is a possible ...mechanism for PM2.5-induced health effects. Organic aerosol (OA) is a dominant component of PM2.5 worldwide, yet its role in PM2.5 toxicity is poorly understood due to its chemical complexity. Here, through integrated cellular ROS measurements and detailed multi-instrument chemical characterization of PM in urban southeastern United States, we show that oxygenated OA (OOA), especially more-oxidized OOA, is the main OA type associated with cellular ROS production. We further reveal that highly unsaturated species containing carbon–oxygen double bonds and aromatic rings in OOA are major contributors to cellular ROS production. These results highlight the key chemical features of ambient OA driving its toxicity. As more-oxidized OOA is ubiquitous and abundant in the atmosphere, this emphasizes the need to understand its sources and chemical processing when formulating effective strategies to mitigate PM2.5 health impacts.
Surfen, a small molecule antagonist of heparan sulfate Schuksz, Manuela; Fuster, Mark M; Brown, Jillian R ...
Proceedings of the National Academy of Sciences - PNAS,
09/2008, Letnik:
105, Številka:
35
Journal Article
Recenzirano
Odprti dostop
In a search for small molecule antagonists of heparan sulfate, we examined the activity of bis-2-methyl-4-amino-quinolyl-6-carbamide, also known as surfen. Fluorescence-based titrations indicated ...that surfen bound to glycosaminoglycans, and the extent of binding increased according to charge density in the order heparin > dermatan sulfate > heparan sulfate > chondroitin sulfate. All charged groups in heparin (N-sulfates, O-sulfates, and carboxyl groups) contributed to binding, consistent with the idea that surfen interacted electrostatically. Surfen neutralized the anticoagulant activity of both unfractionated and low molecular weight heparins and inhibited enzymatic sulfation and degradation reactions in vitro. Addition of surfen to cultured cells blocked FGF2-binding and signaling that depended on cell surface heparan sulfate and prevented both FGF2- and VEGF₁₆₅-mediated sprouting of endothelial cells in Matrigel. Surfen also blocked heparan sulfate-mediated cell adhesion to the Hep-II domain of fibronectin and prevented infection by HSV-1 that depended on glycoprotein D interaction with heparan sulfate. These findings demonstrate the feasibility of identifying small molecule antagonists of heparan sulfate and raise the possibility of developing pharmacological agents to treat disorders that involve glycosaminoglycan-protein interactions.
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