61. Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory : a case study with a long-range transported biomass burning plumeKatja Džepina, Claudio Mazzoleni, Paulo Fialho, Swarup China, Bo Zhang, R. Chris Owen, D. Helmig, J. Hueber, Sumit Kumar, J. A. Perlinger, 2015, original scientific article Abstract: Free tropospheric aerosol was sampled at the
Pico Mountain Observatory located at 2225 m above mean
sea level on Pico Island of the Azores archipelago in the
North Atlantic. The observatory is located ∼ 3900 km east
and downwind of North America, which enables studies
of free tropospheric air transported over long distances.
Aerosol samples collected on filters from June to October
2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 µg m−3
. On average, organic aerosol components represent the largest mass fraction of the total measured aerosol (60 ± 51 %), followed by
sulfate (23 ± 28 %), nitrate (13 ± 10 %), chloride (2 ± 3 %),
and elemental carbon (2 ± 2 %). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and
9/25) collected consecutively during a pollution event were
analyzed using ultrahigh-resolution electrospray ionization
Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned
to each of the mass spectra in the range of m/z 100–1000.
The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled
air masses were very aged (average plume age > 12 days).
These aged aerosol WSOM compounds had an average O /C
ratio of ∼ 0.45, which is relatively low compared to O /C
ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to
biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM
and with the morphology and mixing state of particles as
determined by scanning electron microscopy. The presence
of markers characteristic of aqueous-phase reactions of phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses of 9/25 were
more aged and influenced by marine emissions, as indicated
by the presence of organosulfates and other species characteristic of marine aerosol. The change in the air masses for
the two samples was corroborated by the changes in ethane,
propane, and ozone, morphology of particles, as well as by
the FLEXPART retroplume simulations. This paper presents
the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere
remote location and provides evidence of low oxygenation
after long-range transport. We hypothesize this is a result of
the selective removal of highly aged and polar species during long-range transport, because the aerosol underwent a
combination of atmospheric processes during transport facilitating aqueous-phase removal (e.g., clouds processing) and
fragmentation (e.g., photolysis) of components.
Keywords: organic aerosol, ultrahigh-resolution FT-ICR MS, electron microscopy, remote marine atmosphere, Pico Mountain Observatory
Published in RUNG: 11.04.2021; Views: 2383; Downloads: 0
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62. Molecular and physical characteristics of aerosol at a remote free troposphere site : implications for atmospheric agingSimeon K. Schum, Bo Zhang, Katja Džepina, Paulo Fialho, Claudio Mazzoleni, Lynn R. Mazzoleni, 2018, original scientific article Abstract: Aerosol properties are transformed by atmospheric processes during long-range transport and play a key role in the Earth’s radiative balance. To understand the molecular and physical characteristics of free tropospheric aerosol, we studied samples collected at the Pico Mountain Observatory in the North Atlantic. The observatory is located in the marine free troposphere at 2225m above sea level, on Pico Island in the Azores archipelago. The site is ideal for the study of long-range-transported free tropospheric aerosol with minimal local influence. Three aerosol samples with elevated organic carbon concentrations were selected for detailed analysis. FLEXPART retroplumes indicated that two
of the samples were influenced by North American wildfire
emissions transported in the free troposphere and one by
North American outflow mainly transported within the marine
boundary layer. Ultrahigh-resolution Fourier transform
ion cyclotron resonance mass spectrometry was used to determine
the detailed molecular composition of the samples.
Thousands of molecular formulas were assigned to each of
the individual samples. On average ~60% of the molecular
formulas contained only carbon, hydrogen, and oxygen
atoms (CHO), ~ 30% contained nitrogen (CHNO), and
~ 10% contained sulfur (CHOS). The molecular formula
compositions of the two wildfire-influenced aerosol samples
transported mainly in the free troposphere had relatively low
average O=C ratios (0:48 ± 0:13 and 0:45 ± 0:11) despite the
7–10 days of transport time according to FLEXPART. In contrast,
the molecular composition of the North American outflow
transported mainly in the boundary layer had a higher
average O=C ratio (0:57 ± 0:17) with 3 days of transport time.
To better understand the difference between free tropospheric
transport and boundary layer transport, the meteorological
conditions along the FLEXPART simulated transport pathways
were extracted from the Global Forecast System analysis
for the model grids. We used the extracted meteorological
conditions and the observed molecular chemistry to predict
the relative-humidity-dependent glass transition temperatures
(Tg) of the aerosol components. Comparisons of the
Tg to the ambient temperature indicated that a majority of
the organic aerosol components transported in the free troposphere were more viscous and therefore less susceptible to
oxidation than the organic aerosol components transported
in the boundary layer. Although the number of observations
is limited, the results suggest that biomass burning organic
aerosol injected into the free troposphere is more persistent
than organic aerosol in the boundary layer having broader
implications for aerosol aging.
Keywords: secondary organic aerosols, brown carbon, particle dispersion model, ultrahigh-resolution FT-ICR MS, Pico Mountain Observatory
Published in RUNG: 10.04.2021; Views: 2436; Downloads: 0
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63. Pollutant removal with organic macrocycle-based covalent organic polymers and frameworksTina Škorjanc, Dinesh Shetty, Ali Trabolsi, 2021, review article Abstract: Air, water, and soil pollution devastate countless ecosystems and deteriorate human health. Adsorption has commonly been used as a pollutant removal technique, but ongoing materials science research is still searching for more efficient, cheaper, and scalable sorbent materials. Herein, we discuss the synthesis and pollutant-capturing abilities of covalent polymeric structures, including covalent organic polymers and covalent organic frameworks that contain organic macrocycles in the backbone of their structures. These organic macrocycles (cyclodextrin, calixarene, cucurbituril, pillararene, and porphyrin) possess cavities and functional groups that can sequester pollutants by forming supramolecular interactions. The insolubility of these materials prominently aids in their regeneration and recyclability potentials. Following a discussion on the synthetic strategies used in the polymerization of each type of macrocycle, environmental applications of these materials are presented. Here, we focus on the removal of micropollutants, charged species, metal ions, oils and organic solvents, perfluorinated substances, iodine, and volatile organic compounds.
Keywords: supramolecular interactions, host-guest chemistry, organic macrocycles, covalent polymers, covalent organic frameworks, environmental remediation, adsorption
Published in RUNG: 09.04.2021; Views: 2276; Downloads: 65
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64. Taming the topology of calix[4]arene-based 2D-covalent organic frameworks : interpenetrated vs noninterpenetrated frameworks and their selective removal of cationic dyesBikash Garai, Dinesh Shetty, Tina Škorjanc, Felipe Gándara, Nawavi Naleem, Sabu Varghese, Sudhir Kumar Sharma, Maria Baias, Ramesh Jagannathan, Mark Anthony Olson, 2021, original scientific article Abstract: A bowl-shaped calix[4]arene with its exciting host–guest chemistry is a versatile supramolecular building block for the synthesis of distinct coordination cages or metal–organic frameworks. However, its utility in the synthesis of crystalline covalent organic frameworks (COFs) remains challenging, presumably due to its conformational flexibility. Here, we report the synthesis of a periodic 2D extended organic network of calix[4]arenes joined by a linear benzidine linker via dynamic imine bonds. By tuning the interaction among neighboring calixarene units through varying the concentration in the reaction mixture, we show the selective formation of interpenetrated (CX4-BD-1) and non-interpenetrated (CX4-BD-2) frameworks. The cone-shaped calixarene moiety in the structural backbone allows for the interweaving of two neighboring layers in CX4-BD-1, making it a unique example of interpenetrated 2D layers. Due to the high negative surface charge from calixarene units, both COFs have shown high performance in charge-selective dye removal and an exceptional selectivity for cationic dyes irrespective of their molecular size. The charge distribution of the COFs and the resulting selectivity for the cationic dyes were further investigated using computational methods.
Keywords: dyes and pigments, covalent organic frameworks, adsorption, layers, chemical structure
Published in RUNG: 16.03.2021; Views: 2261; Downloads: 0
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65. Multiresponsive nonvolatile memories based on optically switchable ferroelectric organic field-effect transistorsMarco Carroli, Alex Dixon, Martin Herder, Egon Pavlica, Stefan Hecht, Gvido Bratina, Emanuele Orgiu, Paolo Samorì, 2021, original scientific article Abstract: Organic transistors are key elements for flexible, wearable, and biocompatible logic applications. Multiresponsivity is highly sought‐after in organic electronics to enable sophisticated operations and functions. Such a challenge can be pursued by integrating more components in a single device, each one responding to a specific external stimulus. Here, the first multiresponsive organic device based on a photochromic–ferroelectric organic field‐effect transistor, which is capable of operating as nonvolatile memory with 11 bit memory storage capacity in a single device, is reported. The memory elements can be written and erased independently by means of light or an electric field, with accurate control over the readout signal, excellent repeatability, fast response, and high retention time. Such a proof of concept paves the way toward enhanced functional complexity in optoelectronics via the interfacing of multiple components in a single device, in a fully integrated low‐cost technology compatible with flexible substrates.
Keywords: organic transistors, memory, time-dependent
Published in RUNG: 11.03.2021; Views: 2118; Downloads: 0
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66. Impedimetric, PEDOT:PSS-based organic electrochemical sensor for detection of histamine for precision animal agricultureHuiwen Bai, Kateryna Vyshniakova, Egon Pavlica, Victor Marco Rocha Malacco, Alexandros Yiannikouris, Thirupathi Reddy Yerramreddy, Shawn S. Donkin, Richard M. Voyles, Robert A. Nawrocki, 2020, original scientific article Keywords: organic semiconductors, biosensor, electrochemical transistor
Published in RUNG: 18.02.2021; Views: 2376; Downloads: 140
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68. The peppermint breath test: a benchmarking protocol for breath sampling and analysis using GC-MSMaxim Wilkinson, Iain R. White, Katie Hamshere, Olaf Holz, Sven Schuchardt, Francesca G. Bellagambi, Tommaso Lomonaco, Denise Biagini, Laura Di Francesco, Stephen J. Fowler, 2020, original scientific article Abstract: Exhaled breath contains hundreds of volatile organic compounds (VOCs) which offers the potential for diagnosing and monitoring a wide range of diseases. As the breath research field has grown, sampling and analytical practices have become highly varied between groups. Standardisation would allow meta-analyses of data from multiple studies and greater confidence in published results. The Peppermint Consortium has been formed to address this task of standardisation. In the current study we aimed to generate initial benchmark values for thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) analysis of breath samples containing peppermint-derived VOCs. Headspace analysis of peppermint oil capsules was performed to determine compounds of interest. Ten healthy participants were recruited by three groups. Each participant provided a baseline breath sample prior to taking a peppermint capsule, with further samples collected at 60, 90, 165, 285 and 360 min following ingestion. Sampling and analytical protocols were different for each institution, in line with their usual practice. Samples were analysed by TD-GC-MS and benchmarking values determined for the time taken for detected peppermint VOCs to return to baseline values. Sixteen compounds were identified in the capsule headspace. Additionally, 2,3-dehydro-1,8-cineole was uniquely found in the breath samples, with a washout profile that suggested it was a product of peppermint metabolism. Five compounds (α-pinene, β-pinene, eucalyptol, menthol and menthone) were quantified by all three groups. Differences in recovery were observed between the groups, particularly for menthone and menthol. The average time taken for VOCs to return to baseline was selected as the benchmark and were 441, 648, 1736, 643 and 375 min for α-pinene, β-pinene, eucalyptol, menthone and menthol respectively. An initial set of easy-to-measure benchmarking values for assessing the performance of TD-GC-MS systems for the analysis of VOCs in breath is presented. These values will be updated when more groups provide additional data.
Keywords: Volatile organic compounds, breath, diagnostics, standardisation
Published in RUNG: 11.12.2020; Views: 3066; Downloads: 0
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69. Detection and quantification of exhaled volatile organic compounds in mechanically ventilated patients–comparison of two sampling methodsIain R. White, Pouline M. van Oort, Waqar Ahmed, Craig Johnson, Jonathan Bannard-Smith, Timothy Felton, Lieuwe D. Bos, Royston Goodacre, Paul Dark, Stephen J. Fowler, 2020, original scientific article Abstract: Exhaled breath analysis is a promising new diagnostic tool, but currently no standardised method for sampling is available in mechanically ventilated patients. We compared two breath sampling methods, first using an artificial ventilator circuit, then in “real life” in mechanically ventilated patients on the intensive care unit. In the laboratory circuit, a 24-component synthetic-breath volatile organic compound (VOC) mixture was injected into the system as air was sampled: (A) through a port on the exhalation limb of the circuit and (B) through a closed endo-bronchial suction catheter. Sorbent tubes were used to collect samples for analysis by thermal desorption-gas chromatography-mass spectrometry. Realistic mechanical ventilation rates and breath pressure–volume loops were established and method detection limits (MDLs) were calculated for all VOCs. Higher yields of VOCs were retrieved using the closed suction catheter; however, for several VOCs MDLs were compromised due to the background signal associated with plastic and rubber components in the catheters. Different brands of suction catheter were compared. Exhaled VOC data from 40 patient samples collected at two sites were then used to calculate the proportion of data analysed above the MDL. The relative performance of the two methods differed depending on the VOC under study and both methods showed sensitivity towards different exhaled VOCs. Furthermore, method performance differed depending on recruitment site, as the centres were equipped with different brands of respiratory equipment, an important consideration for the design of multicentre studies investigating exhaled VOCs in mechanically ventilated patients.
Keywords: Volatile organic compounds, infection, breath, ventilator associated pneumonia
Published in RUNG: 10.12.2020; Views: 2543; Downloads: 0
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70. Ultraviolet absorption and transient photocurrent spectroscopy in organic thin layers as evidence of super atomic molecular orbitals in corannuleneNadiia Pastukhova, Layla Martin-Samos, Laura Zoppi, Egon Pavlica, Jinta Mathew, Gvido Bratina, J. S. Siegel, Kim K. Baldridge, 2018, published scientific conference contribution abstract Keywords: photocurrent spectroscopy, organic thin layers, atomic molecular orbitals
Published in RUNG: 03.11.2020; Views: 2641; Downloads: 71
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