elemental mass
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2021 ◽  
Author(s):  
Denice van Herwerden ◽  
Jake O'Brien ◽  
Phil Choi ◽  
Kevin Thomas ◽  
Peter Schoenmakers ◽  
...  

Isotopologue identification or removal is a necessary step to reduce the number of features that need to be identified in samples analyzed with non-targeted analysis. Currently available approaches rely on either predicted isotopic patterns or an arbitrary mass tolerance, requiring information on the molecular formula or instrumental error, respectively. Therefore, a Naive Bayes isotopologue classification model was developed that does not depend on any thresholds or molecular formula information. This classification model uses elemental mass defects of six elemental ratios and can successfully identify isotopologues in both theoretical isotopic patterns and wastewater influent samples, outperforming one of the most commonly used approaches (i.e., 1.0033 Da mass difference method - CAMERA).


2021 ◽  
Vol 21 (19) ◽  
pp. 14471-14492
Author(s):  
Magdalena Reizer ◽  
Giulia Calzolai ◽  
Katarzyna Maciejewska ◽  
José A. G. Orza ◽  
Luca Carraresi ◽  
...  

Abstract. The elemental composition of the fine (PM2.5) and coarse (PM2.5−10) fraction of atmospheric particulate matter was measured at an hourly time resolution by the use of a streaker sampler during a winter period at a Central European urban background site in Warsaw, Poland. A combination of multivariate (Positive Matrix Factorization) and wind- (Conditional Probability Function) and trajectory-based (Cluster Analysis) receptor models was applied for source apportionment. It allowed for the identification of five similar sources in both fractions, including sulfates, soil dust, road salt, and traffic- and industry-related sources. Another two sources, i.e., Cl-rich and wood and coal combustion, were solely identified in the fine fraction. In the fine fraction, aged sulfate aerosol related to emissions from domestic solid fuel combustion in the outskirts of the city was the largest contributing source to fine elemental mass (44 %), while traffic-related sources, including soil dust mixed with road dust, road dust, and traffic emissions, had the biggest contribution to the coarse elemental mass (together accounting for 83 %). Regional transport of aged aerosols and more local impact of the rest of the identified sources played a crucial role in aerosol formation over the city. In addition, two intensive Saharan dust outbreaks were registered on 18 February and 8 March 2016. Both episodes were characterized by the long-range transport of dust at 1500 and 3000 m over Warsaw and the concentrations of the soil component being 7 (up to 3.5 µg m−3) and 6 (up to 6.1 µg m−3) times higher than the mean concentrations observed during non-episodes days (0.5 and 1.1 µg m−3) in the fine and coarse fractions, respectively. The set of receptor models applied to the high time resolution data allowed us to follow, in detail, the daily evolution of the aerosol elemental composition and to identify distinct sources contributing to the concentrations of the different PM fractions, and it revealed the multi-faceted nature of some elements with diverse origins in the fine and coarse fractions. The hourly resolution of meteorological conditions and air mass back trajectories allowed us to follow the transport pathways of the aerosol as well.


Author(s):  
Fithriyyah Karimah ◽  
Tico G Samosir ◽  
Fuaddinda P Salsabila

Hydrogen or sometimes called water, is a chemical element on the periodic table that has the symbol H and atomic number 1. At standard temperatures and pressures, hydrogen is colorless, odorless, non-metallic, singlevalent, and a highly flammable diatomic gas. With an atomic mass of 1.00794 amu, hydrogen is the lightest element in the world. It is also the most abundant element, accounting for roughly 75% of the total elemental mass of the universe. Most stars are formed by hydrogen in the plasma state. Hydrogen compounds are relatively rare and rarely found naturally on Earth, and are usually produced industrially from various hydrocarbons such as methane. Hydrogen can also be produced from water through electrolysis, but this process is more expensive commercially than producing hydrogen from natural gas. With the aim to prove the explosion that occurred and the reaction that occurred during the experimental process of an exothermic or endoderm reaction explosion


2021 ◽  
Author(s):  
Magdalena Reizer ◽  
Giulia Calzolai ◽  
Katarzyna Maciejewska ◽  
José A. G. Orza ◽  
Luca Carraresi ◽  
...  

Abstract. Elemental composition of the fine (PM2.5) and coarse (PM2.5-10) fraction of atmospheric particulate matter was measured at hourly time resolution by the use of a “streaker” sampler during a winter period at a Central European urban background site in Warsaw, Poland. A combination of multivariate (Positive Matrix Factorization), wind- (Conditional Probability Function) and trajectory-based (Cluster Analysis) receptor models, was applied for source apportionment. It allowed for identification of 5 similar sources in both fractions, including sulfates, soil dust, road salt, traffic- and industry-related sources. Another 2 sources, i.e., Cl-rich and wood and waste combustion, were identified in the fine fraction solely. In the fine fraction, aged sulfate aerosol related with emissions from solid fuel combustion in the residential sector located outside the city was the largest contributing source to fine elemental mass (44 %), while traffic-related sources, including soil dust mixed with road dust, road dust, as well as exhaust and non-exhaust traffic emissions, had the biggest contribution in the coarse elemental mass (together accounting for 83 %). Regional transport of aged aerosols and more local impact of the rest of identified sources played a crucial role in aerosol formation over the city. In addition, 2 intensive Saharan dust outbreaks were registered on 18th February and 8th March 2016. Both episodes were characterized by long-range transport of dust at 1 500 m and 3 000 m over Warsaw, as well as the concentrations of the soil component being 7 (up to 3.5 µg m−3) and 6 (up to 6.1 µg m−3) times higher than the mean concentrations observed during non-episodes days (0.5 µg m−3 and 1.1 µg m−3) in the fine and coarse fraction, respectively. The set of receptor models applied to the high time resolution data allowed to follow in detail the daily evolution of the aerosol elemental composition and to identify distinct sources contributing to the concentrations of different PM fractions, as well as revealed “multi-faces” of some elements, having diverse origin in the fine and coarse fraction. The hourly resolution of meteorological conditions and air mass back trajectories empower to follow transport pathways of the aerosol as well.


2021 ◽  
Author(s):  
Xiao-Le Deng ◽  
Wen-Bin Shen ◽  
Meng Yang ◽  
Jiangjun Ran

<p>The tensor invariants (or invariants of tensors) for gravity gradient tensors (GGT, the second-order derivatives of the gravitational potential (GP)) have the advantage of not changing with the rotation of the corresponding coordinate system, which were widely applied in the study of gravity field (e.g., recovery of global gravity field, geophysical exploration, and gravity matching for navigation and positioning). With the advent of gravitational curvatures (GC, the third-order derivatives of the GP), the new definition of tensor invariants for gravitational curvatures can be proposed. In this contribution, the general expressions for the principal and main invariants of gravitational curvatures (PIGC and MIGC denoted as I and J systems) are presented. Taking the tesseroid, rectangular prism, sphere, and spherical shell as examples, the detailed expressions for the PIGC and MIGC are derived for these elemental mass bodies. Simulated numerical experiments based on these new expressions are performed compared to other gravity field parameters (e.g., GP, gravity vector (GV), GGT, GC, and tensor invariants for the GGT). Numerical results show that the PIGC and MIGC can provide additional information for the GC. Furthermore, the potential applications for the PIGC and MIGC are discussed both in spatial and spectral domains for the gravity field.</p>


2021 ◽  
Vol 144 ◽  
pp. 104269
Author(s):  
Matthew T. Dorsey ◽  
Thomas K. Rockwell ◽  
Gary H. Girty ◽  
Giles A. Ostermeijer ◽  
John Browning ◽  
...  

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