東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back

Switch To: Labeled | MARC Mode | ISBD

Molecular Characterization of Free T...

Schum, Simeon K.

Linked to FindBook

Google Book

Amazon

博客來

Molecular Characterization of Free Tropospheric Organic Aerosol and the Development of Computational Tools for Molecular Formula Assignment.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Molecular Characterization of Free Tropospheric Organic Aerosol and the Development of Computational Tools for Molecular Formula Assignment./
Author:	Schum, Simeon K.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
Description:	273 p.
Notes:	Source: Dissertation Abstracts International, Volume: 80-09(E), Section: B.
Contained By:	Dissertation Abstracts International80-09B(E).
Subject:	Atmospheric chemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=13863466
ISBN:	9781392173596

Molecular Characterization of Free Tropospheric Organic Aerosol and the Development of Computational Tools for Molecular Formula Assignment.
Schum, Simeon K.

Molecular Characterization of Free Tropospheric Organic Aerosol and the Development of Computational Tools for Molecular Formula Assignment. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 273 p.

Source: Dissertation Abstracts International, Volume: 80-09(E), Section: B.

Thesis (Ph.D.)--Michigan Technological University, 2019.

Organic aerosol affects human health and climate. These effects are largely determined by the composition of the organic aerosol, which is a complex mixture of species. Understanding the complexity of organic aerosol is critical to determining its effect on human health and climate. In this study, long range transported organic aerosol collected at the Pico Mountain Observatory was analyzed using ultrahigh resolution mass spectrometry. Organic aerosol transported in the free troposphere had an overall lower extent of oxidation than aerosol transported in the boundary layer. It was hypothesized that the lower oxidation was related to a more viscous phase state of the aerosol during transport. The results suggest that biomass burning organic aerosol injected into the free troposphere are more persistent than organic aerosol in the boundary layer. A sample was also analyzed using tandem FT-ICR MS/MS fragmentation, providing information about the functional group composition in the aerosol sample. This was done using a segmented scan approach, which revealed an unprecedented molecular complexity of unfragmented precursor ions. In addition to the expected CO2 and H2O neutral losses, neutral losses corresponding to carbonyl functional groups (C2H4O, CO) were observed. The abundance of carbonyl functional groups suggests a slower rate of aging in the atmosphere. Analysis of nitrogen and sulfur containing neutral losses highlighted a surprising abundance of reduced nitrogen and sulfur loss (NH3 and SH2). This further supports the hypothesis of slower aging in the free troposphere. Additional research was done to develop an R software package (MFAssignR) to perform molecular formula assignment with improved decision-making transparency, noise estimation, isotope identification, and mass recalibration. MFAssignR was found to assign the same molecular formula as other molecular formula assignment methods for the majority (97--99%) of mass peaks that were assigned a molecular formula by the compared methods. Additionally, MFAssignR was more effective at assigning molecular formulas to low intensity peaks relative to the other methods tested, leading to more overall molecular formula assignments. MFAssignR is available via GitHub and is the first open source package to contain a full pipeline of functions for data preparation and analysis for ultrahigh resolution mass spectrometry.

ISBN: 9781392173596Subjects--Topical Terms:

544140
Atmospheric chemistry.

Molecular Characterization of Free Tropospheric Organic Aerosol and the Development of Computational Tools for Molecular Formula Assignment.
LDR:03462nmm a2200313 4500 001 2204101
005 20190624102129.5
008 201008s2019 ||||||||||||||||| ||eng d
020 $a 9781392173596
035 $a (MiAaPQ)AAI13863466
035 $a (MiAaPQ)michigantech:11702
035 $a AAI13863466
040 $a MiAaPQ $c MiAaPQ
100 1 $a Schum, Simeon K. $0 (orcid)0000-0001-8988-5236 $3 3430920
245 1 0 $a Molecular Characterization of Free Tropospheric Organic Aerosol and the Development of Computational Tools for Molecular Formula Assignment.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2019
300 $a 273 p.
500 $a Source: Dissertation Abstracts International, Volume: 80-09(E), Section: B.
500 $a Adviser: Lynn R. Mazzoleni.
502 $a Thesis (Ph.D.)--Michigan Technological University, 2019.
520 $a Organic aerosol affects human health and climate. These effects are largely determined by the composition of the organic aerosol, which is a complex mixture of species. Understanding the complexity of organic aerosol is critical to determining its effect on human health and climate. In this study, long range transported organic aerosol collected at the Pico Mountain Observatory was analyzed using ultrahigh resolution mass spectrometry. Organic aerosol transported in the free troposphere had an overall lower extent of oxidation than aerosol transported in the boundary layer. It was hypothesized that the lower oxidation was related to a more viscous phase state of the aerosol during transport. The results suggest that biomass burning organic aerosol injected into the free troposphere are more persistent than organic aerosol in the boundary layer. A sample was also analyzed using tandem FT-ICR MS/MS fragmentation, providing information about the functional group composition in the aerosol sample. This was done using a segmented scan approach, which revealed an unprecedented molecular complexity of unfragmented precursor ions. In addition to the expected CO2 and H2O neutral losses, neutral losses corresponding to carbonyl functional groups (C2H4O, CO) were observed. The abundance of carbonyl functional groups suggests a slower rate of aging in the atmosphere. Analysis of nitrogen and sulfur containing neutral losses highlighted a surprising abundance of reduced nitrogen and sulfur loss (NH3 and SH2). This further supports the hypothesis of slower aging in the free troposphere. Additional research was done to develop an R software package (MFAssignR) to perform molecular formula assignment with improved decision-making transparency, noise estimation, isotope identification, and mass recalibration. MFAssignR was found to assign the same molecular formula as other molecular formula assignment methods for the majority (97--99%) of mass peaks that were assigned a molecular formula by the compared methods. Additionally, MFAssignR was more effective at assigning molecular formulas to low intensity peaks relative to the other methods tested, leading to more overall molecular formula assignments. MFAssignR is available via GitHub and is the first open source package to contain a full pipeline of functions for data preparation and analysis for ultrahigh resolution mass spectrometry.
590 $a School code: 0129.
650 4 $a Atmospheric chemistry. $3 544140
650 4 $a Analytical chemistry. $3 3168300
650 4 $a Chemistry. $3 516420
690 $a 0371
690 $a 0486
690 $a 0485
710 2 $a Michigan Technological University. $b Chemistry. $3 3430921
773 0 $t Dissertation Abstracts International $g 80-09B(E).
790 $a 0129
791 $a Ph.D.
792 $a 2019
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=13863466