Elemental ratio measurements of organic compounds  using aerosol mass spectrometry: characterization,  improved calibration, and implications

Abstract. Elemental compositions of organic aerosol (OA) particles provide useful constraints on OA sources, chemical evolution, and effects. The Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) is widely used to measure OA elemental composition. This study evaluates AMS measurements of atomic oxygen-to-carbon (O : C), hydrogen-to-carbon (H : C), and organic mass-to-organic carbon (OM : OC) ratios, and of carbon oxidation state (OS C) for a vastly expanded laboratory data set of multifunctional oxidized OA standards. For the expanded standard data set, the method introduced by Aiken et al. (2008), which uses experimentally measured ion intensities at all ions to determine elemental ratios (referred to here as "Aiken-Explicit"), reproduces known O : C and H : C ratio values within 20% (average absolute value of relative errors) and 12%, respectively. The more commonly used method, which uses empirically estimated H2O+ and CO+ ion intensities to avoid gas phase air interferences at these ions (referred to here as "Aiken-Ambient"), reproduces O : C and H : C of multifunctional oxidized species within 28 and 14% of known values. The values from the latter method are systematically biased low, however, with larger biases observed for alcohols and simple diacids. A detailed examination of the H2O+, CO+, and CO2+ fragments in the high-resolution mass spectra of the standard compounds indicates that the Aiken-Ambient method underestimates the CO+ and especially H2O+ produced from many oxidized species. Combined AMS–vacuum ultraviolet (VUV) ionization measurements indicate that these ions are produced by dehydration and decarboxylation on the AMS vaporizer (usually operated at 600 °C). Thermal decomposition is observed to be efficient at vaporizer temperatures down to 200 °C. These results are used together to develop an "Improved-Ambient" elemental analysis method for AMS spectra measured in air. The Improved-Ambient method uses specific ion fragments as markers to correct for molecular functionality-dependent systematic biases and reproduces known O : C (H : C) ratios of individual oxidized standards within 28% (13%) of the known molecular values. The error in Improved-Ambient O : C (H : C) values is smaller for theoretical standard mixtures of the oxidized organic standards, which are more representative of the complex mix of species present in ambient OA. For ambient OA, the Improved-Ambient method produces O : C (H : C) values that are 27% (11%) larger than previously published Aiken-Ambient values; a corresponding increase of 9% is observed for OM : OC values. These results imply that ambient OA has a higher relative oxygen content than previously estimated. The OS C values calculated for ambient OA by the two methods agree well, however (average relative difference of 0.06 OS C units). This indicates that OS C is a more robust metric of oxidation than O : C, likely since OS C is not affected by hydration or dehydration, either in the atmosphere or during analysis.

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Elemental ratio measurements of organic compounds using aerosol mass spectrometry: characterization, improved calibration, and implications

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-19791-2014 ◽

2014 ◽

Vol 14 (13) ◽

pp. 19791-19835 ◽

Cited By ~ 13

Author(s):

M. R. Canagaratna ◽

J. L. Jimenez ◽

J. H. Kroll ◽

Q. Chen ◽

S. H. Kessler ◽

...

Keyword(s):

High Resolution ◽

Vacuum Ultraviolet ◽

Detailed Examination ◽

Relative Difference ◽

Elemental Ratios ◽

Aerosol Mass Spectrometer ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry ◽

Systematic Biases ◽

Relative Errors

Abstract. Elemental compositions of organic aerosol (OA) particles provide useful constraints on OA sources, chemical evolution, and effects. The Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) is widely used to measure OA elemental composition. This study evaluates AMS measurements of atomic oxygen-to-carbon (O : C), hydrogen-to-carbon (H : C), organic mass-to-organic carbon (OM : OC), and carbon oxidation state (OSC) for a vastly expanded laboratory dataset of multifunctional oxidized OA standards. For the expanded standard dataset, the "Aiken-Explicit" method (Aiken et al., 2008), which uses experimentally measured ion intensities at all ions to determine elemental ratios, reproduces known molecular O : C and H : C ratio values within 20% (average absolute value of relative errors) and 12% respectively. The more commonly used "Aiken-Ambient" method, which uses empirically estimated H2O+ and CO+ ion intensities to avoid gas phase air interferences at these ions, reproduces O : C and H : C of multifunctional oxidized species within 28% and 14% of known values. These values are systematically biased low, however, with larger biases observed for alcohols and simple diacids. A detailed examination of the H2O+, CO+, and CO2+ fragments in the high-resolution mass spectra of the standard compounds indicates that the Aiken-Ambient method underestimates the CO+ and H2O+ produced from many oxidized species. Combined AMS-vacuum ultraviolet (VUV) ionization measurements indicate that these ions are produced by dehydration and decarboxylation on the AMS vaporizer (usually operated at 600 °C). Thermal decomposition is observed to be efficient at vaporizer temperatures down to 200 °C. These results are used together to develop an "Improved-Ambient" elemental analysis method for AMS spectra measured in air. The Improved-Ambient method reduces the systematic biases and reproduces O : C (H : C) ratios of individual oxidized standards within 28% (13%) of the known molecular values. The error in Improved-Ambient O : C and H : C values is smaller (12% and 4% respectively) for synthetic mixtures of the oxidized organic standards, which are more representative of the complex mix of species present in ambient OA. For ambient OA, the Improved-Ambient method produces O : C (H : C) values that are 27% (11%) larger than previously published Aiken-Ambient values; a corresponding increase of 9% is observed for OM : OC values. These results imply that ambient OA has a higher relative oxygen content than previously estimated. The OSC values calculated for ambient OA by the two methods agree well, however (average relative difference of 0.06 OSC units). This indicates that OSC is a more robust metric of oxidation than O : C, likely since OSC is not affected by hydration or dehydration, either in the atmosphere or during analysis.

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Algorithms for automated montage synthesis of images from laser-scanning confocal microscopes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100139627 ◽

1995 ◽

Vol 53 ◽

pp. 650-651

Author(s):

D. E. Becker

Keyword(s):

Image Analysis ◽

High Resolution ◽

Laser Scanning ◽

Cell Counting ◽

Wide Area ◽

Data Set ◽

Computational Synthesis ◽

Automated Cell Counting ◽

Partial View ◽

The Individual

An efficient, robust, and widely-applicable technique is presented for computational synthesis of high-resolution, wide-area images of a specimen from a series of overlapping partial views. This technique can also be used to combine the results of various forms of image analysis, such as segmentation, automated cell counting, deblurring, and neuron tracing, to generate representations that are equivalent to processing the large wide-area image, rather than the individual partial views. This can be a first step towards quantitation of the higher-level tissue architecture. The computational approach overcomes mechanical limitations, such as hysterisis and backlash, of microscope stages. It also automates a procedure that is currently done manually. One application is the high-resolution visualization and/or quantitation of large batches of specimens that are much wider than the field of view of the microscope.The automated montage synthesis begins by computing a concise set of landmark points for each partial view. The type of landmarks used can vary greatly depending on the images of interest. In many cases, image analysis performed on each data set can provide useful landmarks. Even when no such “natural” landmarks are available, image processing can often provide useful landmarks.

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The Study of Multiple Classes Boosting Classification Method Based on Local Similarity

Algorithms ◽

10.3390/a14020037 ◽

2021 ◽

Vol 14 (2) ◽

pp. 37

Author(s):

Shixun Wang ◽

Qiang Chen

Keyword(s):

Image Retrieval ◽

Loss Function ◽

Single Mode ◽

Local Similarity ◽

Text And Image ◽

Data Set ◽

Standard Data ◽

Weak Learner ◽

Great Progress ◽

Data Points

Boosting of the ensemble learning model has made great progress, but most of the methods are Boosting the single mode. For this reason, based on the simple multiclass enhancement framework that uses local similarity as a weak learner, it is extended to multimodal multiclass enhancement Boosting. First, based on the local similarity as a weak learner, the loss function is used to find the basic loss, and the logarithmic data points are binarized. Then, we find the optimal local similarity and find the corresponding loss. Compared with the basic loss, the smaller one is the best so far. Second, the local similarity of the two points is calculated, and then the loss is calculated by the local similarity of the two points. Finally, the text and image are retrieved from each other, and the correct rate of text and image retrieval is obtained, respectively. The experimental results show that the multimodal multi-class enhancement framework with local similarity as the weak learner is evaluated on the standard data set and compared with other most advanced methods, showing the experience proficiency of this method.

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A comprehensive evaluation of aerosol extinction apportionment in Beijing using a high-resolution time-of-flight aerosol mass spectrometer

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.146976 ◽

2021 ◽

Vol 783 ◽

pp. 146976

Author(s):

Lingbin Kong ◽

Jinyuan Xin ◽

Wenkang Gao ◽

Guiqian Tang ◽

Xuemei Wang ◽

...

Keyword(s):

High Resolution ◽

Mass Spectrometer ◽

Comprehensive Evaluation ◽

Time Of Flight ◽

Aerosol Extinction ◽

Resolution Time ◽

Aerosol Mass Spectrometer ◽

Aerosol Mass

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Predissociation supported high‐resolution vacuum ultraviolet absorption spectroscopy of excited electronic states of NH3

The Journal of Chemical Physics ◽

10.1063/1.467341 ◽

1994 ◽

Vol 101 (7) ◽

pp. 5523-5528 ◽

Cited By ~ 15

Author(s):

Xinghua Li ◽

Carl Rudolf Vidal

Keyword(s):

High Resolution ◽

Absorption Spectroscopy ◽

Vacuum Ultraviolet ◽

Electronic States ◽

Ultraviolet Absorption ◽

Excited Electronic States ◽

Ultraviolet Absorption Spectroscopy

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A high-resolution model of the inner organs based on the visible muman data set

Journal of Visualization ◽

10.1007/bf03182328 ◽

2002 ◽

Vol 5 (3) ◽

pp. 212-212 ◽

Cited By ~ 1

Author(s):

U. Tiede ◽

A. Pommert ◽

B. Pflesser ◽

E. Richter ◽

M. Riemer ◽

...

Keyword(s):

High Resolution ◽

Data Set ◽

Inner Organs ◽

Resolution Model ◽

High Resolution Model

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Performance of the vacuum ultraviolet high-resolution and high-flux beamline for chemical dynamics studies at the Advanced Light Source

Review of Scientific Instruments ◽

10.1063/1.1148082 ◽

1997 ◽

Vol 68 (5) ◽

pp. 1945-1951 ◽

Cited By ~ 147

Author(s):

P. A. Heimann ◽

M. Koike ◽

C. W. Hsu ◽

D. Blank ◽

X. M. Yang ◽

...

Keyword(s):

High Resolution ◽

Light Source ◽

Vacuum Ultraviolet ◽

High Flux ◽

Chemical Dynamics ◽

Advanced Light Source

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TNO-MACC_II emission inventory; a multi-year (2003–2009) consistent high-resolution European emission inventory for air quality modelling

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-10963-2014 ◽

2014 ◽

Vol 14 (20) ◽

pp. 10963-10976 ◽

Cited By ~ 200

Author(s):

J. J. P. Kuenen ◽

A. J. H. Visschedijk ◽

M. Jozwicka ◽

H. A. C. Denier van der Gon

Keyword(s):

Particulate Matter ◽

Air Quality ◽

High Resolution ◽

Emission Inventory ◽

Point Sources ◽

Air Quality Modelling ◽

Emission Data ◽

Data Set ◽

Spatially Distributed ◽

Reported Data

Abstract. Emissions to air are reported by countries to EMEP. The emissions data are used for country compliance checking with EU emission ceilings and associated emission reductions. The emissions data are also necessary as input for air quality modelling. The quality of these "official" emissions varies across Europe. As alternative to these official emissions, a spatially explicit high-resolution emission inventory (7 × 7 km) for UNECE-Europe for all years between 2003 and 2009 for the main air pollutants was made. The primary goal was to supply air quality modellers with the input they need. The inventory was constructed by using the reported emission national totals by sector where the quality is sufficient. The reported data were analysed by sector in detail, and completed with alternative emission estimates as needed. This resulted in a complete emission inventory for all countries. For particulate matter, for each source emissions have been split in coarse and fine particulate matter, and further disaggregated to EC, OC, SO4, Na and other minerals using fractions based on the literature. Doing this at the most detailed sectoral level in the database implies that a consistent set was obtained across Europe. This allows better comparisons with observational data which can, through feedback, help to further identify uncertain sources and/or support emission inventory improvements for this highly uncertain pollutant. The resulting emission data set was spatially distributed consistently across all countries by using proxy parameters. Point sources were spatially distributed using the specific location of the point source. The spatial distribution for the point sources was made year-specific. The TNO-MACC_II is an update of the TNO-MACC emission data set. Major updates included the time extension towards 2009, use of the latest available reported data (including updates and corrections made until early 2012) and updates in distribution maps.

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