The enhanced mixing states of oxalate with metals in single particles in Guangzhou, China

Abstract. The mixing states of particulate amines with different chemical components are of great significance in studying the formation and evolution processes of amine-containing particles. In this work, the mixing states of single particles containing trimethylamine (TMA) and diethylamine (DEA) are investigated using a high-performance single-particle aerosol mass spectrometer located in Nanjing, China, in September 2019. TMA- and DEA-containing particles accounted for 22.8 % and 5.5 % of the total detected single particles, respectively. The particle count and abundance of the TMA-containing particles in the total particles notably increased with enhancement of ambient relative humidity (RH), while the DEA-containing particles showed no increase under a high RH. This result suggested the important role of RH in the formation of particulate TMA. Significant enrichments of secondary organic species, including 43C2H3O+, 26CN−, 42CNO−, 73C3H5O2-, and 89HC2O4-, were found in DEA-containing particles, indicating that DEA-containing particles were closely associated with the aging of secondary organics. The differential mass spectra of the DEA-containing particles showed a much higher abundance of nitrate and organic nitrogen species during the nighttime than during the daytime, which suggested that the nighttime production of particulate DEA might be associated with reactions of gaseous DEA with HNO3 and/or particulate nitrate. In the daytime, the decrease in DEA-containing particles was observed with the enrichment of oxalate and glyoxylate, which suggested a substantial impact of photochemistry on the aging process of DEA-containing particles. Furthermore, more than 80 % of TMA- and DEA-containing particles internally mixed with nitrate, while the abundance of sulfate was higher in the DEA-containing particles (79.3 %) than in the TMA-containing particles (55.3 %). This suggested that particulate DEA existed both as nitrate and sulfate aminium salts, while the particulate TMA primarily presented as nitrate aminium salt. The different mixing states of the TMA- and DEA-containing particles suggested their different formation processes and various influencing factors, which are difficult to investigate using bulk analysis. These results provide insights into the discriminated fates of organics during the evolution process in aerosols, which helps to illustrate the behavior of secondary organic aerosols.

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Diverse mixing states of amine-containing single particles in Nanjing, China

10.5194/acp-2021-593 ◽

2021 ◽

Author(s):

Qi En Zhong ◽

Chunlei Cheng ◽

Zaihua Wang ◽

Lei Li ◽

Mei Li ◽

...

Keyword(s):

High Performance ◽

Sharp Decrease ◽

Chemical Components ◽

Single Particles ◽

Bulk Analysis ◽

Substantial Impact ◽

Particle Count ◽

Ambient Relative Humidity ◽

Aerosol Mass ◽

Mixing States

Abstract. The mixing states of particulate amines with different chemical components are of great significance in studying the formation and evolution processes of amine-containing particles. In this work, the mixing states of single particles containing trimethylamine (TMA) and diethylamine (DEA) are investigated in order to study the formation and aging processes of the single particles using a high-performance single-particle aerosol mass spectrometer located in Nanjing, China, in September 2019. TMA- and DEA-containing particles accounted for 22.8 % and 5.5 % of the total detected single particles, respectively. The particle count and abundance of the TMA-containing particles in total particles notably increased with enhancement of ambient relative humidity (RH), while the DEA-containing particles showed no increase under a high RH. This result suggested the important role of RH in the formation of particulate TMA. Significant enrichments of secondary organic species, including 43C2H3O+, 26CN−, 42CNO−, 73C3H5O2−, and 89HC2O4−, were found in DEA-containing particles, indicating that DEA-containing particles were closely associated with the aging of secondary organics. The particle count and abundance of DEA-containing particles showed a prominent increase during the nighttime, but a sharp decrease during the afternoon. Furthermore, the differential mass spectra of the DEA-containing particles showed a much higher abundance of nitrate during the nighttime than during the daytime. In addition, the number fraction of organic nitrogen species in the DEA-containing particles and ambient NOx both showed consistent increasing trends, similar to the accumulation of DEA-containing particles during the nighttime. This suggested that the nighttime production of particulate DEA might be associated with reactions of gaseous DEA with HNO3 and/or particulate nitrate. Higher abundances of oxalate and glyoxylate were found in DEA-containing particles during the strong photochemistry period when the abundance of DEA-containing particles decreased to the lowest of the total particles. This result suggested a substantial impact of photochemistry on the aging process of DEA-containing particles. Further, greater than 80 % of TMA- and DEA-containing particles internally mixed with nitrate, while the abundance of sulfate was higher in the DEA-containing particles (79.3 %) than in the TMA-containing particles (55.3 %). In addition, a lesser amount of ammonium was found in the DEA-containing particles (13.2 %) compared with the TMA-containing particles (35 %). These observations suggested that particulate DEA existed both as nitrate and sulfate aminium salts, while the particulate TMA primarily presented as nitrate aminium salt. Overall, the different mixing states of the TMA- and DEA-containing particles suggested their different formation processes and various influencing factors, which are difficult to be investigated using bulk analysis. These results provide insights into the discriminated fates of organics during the evolution process in aerosols, which provides a better illustration of the behavior of secondary organic aerosols.

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Application of Single-Particle Mass Spectrometer to Obtain Chemical Signatures of Various Combustion Aerosols

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph182111580 ◽

2021 ◽

Vol 18 (21) ◽

pp. 11580

Author(s):

Hee-joo Cho ◽

Joonwoo Kim ◽

Nohhyeon Kwak ◽

Heesung Kwak ◽

Taewan Son ◽

...

Keyword(s):

Single Particle ◽

Mass Spectra ◽

Fine Particles ◽

Particle Mass ◽

Single Particles ◽

Engine Exhaust ◽

Diesel Engine Exhaust ◽

Chemical Signatures ◽

Combustion Aerosols ◽

Mixing States

A single-particle mass spectrometer (SPMS) with laser ionization was constructed to determine the chemical composition of single particles in real time. The technique was evaluated using various polystyrene latex particles with different sizes (125 nm, 300 nm, 700 nm, and 1000 nm); NaCl, KCl, MgCO3, CaCO3, and Al2O3 particles with different chemical compositions; an internal mixture of NaCl and KCl; and an internal mixture of NaCl, KCl, and MgCl2 with different mixing states. The results show that the SPMS can be useful for the determination of chemical characteristics and mixing states of single particles in real time. The SPMS was then applied to obtain the chemical signatures of various combustion aerosols (diesel engine exhaust, biomass burning (rice straw), coal burning, and cooking (pork)) based on their single-particle mass spectra. Elemental carbon (EC)-rich and EC-organic carbon (OC) particles were the predominant particle types identified in diesel engine exhaust, while K-rich and EC-OC-K particles were observed among rice straw burning emissions. Only one particle type (ash-rich particles) was detected among coal burning emissions. EC-rich and EC-OC particles were observed among pork burning particles. The single-particle mass spectra of the EC or OC types of particles differed among various combustion sources. The observed chemical signatures could be useful for rapidly identifying sources of atmospheric fine particles. In addition, the detected chemical signatures of the fine particles may be used to estimate their toxicity and to better understand their effects on human health.

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3-D reconstruction of molecular shape from microcrystal thin sections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077311 ◽

1983 ◽

Vol 41 ◽

pp. 748-749

Author(s):

S. Cusack ◽

J.-C. Jésior

Keyword(s):

Three Dimensional ◽

Molecular Shape ◽

Biological Molecules ◽

Fourier Space ◽

Single Particles ◽

Thin Sections ◽

Standard Methods ◽

X Ray ◽

X Ray Crystallography ◽

Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

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Computer Assisted Image Reconstruction of Oligomer Structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092323 ◽

1976 ◽

Vol 34 ◽

pp. 472-473

Author(s):

A.M. Jones ◽

A. Max Fiskin

Keyword(s):

Three Dimensional ◽

Depth Of Field ◽

Computer Assisted ◽

Projection Data ◽

Two Dimensional ◽

Single Particles ◽

Dimensional Reconstruction ◽

Computer Assisted Image ◽

The Fourier Transform ◽

Space Approach

If the tilt of a specimen can be varied either by the strategy of observing identical particles orientated randomly or by use of a eucentric goniometer stage, three dimensional reconstruction procedures are available (l). If the specimens, such as small protein aggregates, lack periodicity, direct space methods compete favorably in ease of implementation with reconstruction by the Fourier (transform) space approach (2). Regardless of method, reconstruction is possible because useful specimen thicknesses are always much less than the depth of field in an electron microscope. Thus electron images record the amount of stain in columns of the object normal to the recording plates. For single particles, practical considerations dictate that the specimen be tilted precisely about a single axis. In so doing a reconstructed image is achieved serially from two-dimensional sections which in turn are generated by a series of back-to-front lines of projection data.

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New challenges to image processing posed by cryo-Electron microscopy of single particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086416 ◽

1991 ◽

Vol 49 ◽

pp. 422-423

Author(s):

Joachim Frank

Keyword(s):

Electron Microscopy ◽

Phase Contrast ◽

Particle Orientation ◽

Single Particles ◽

Contrast Transfer Function ◽

Virtual Absence ◽

Cryo Electron Microscopy ◽

Spatial Frequencies ◽

New Challenges ◽

Particle Images

Compared with images of negatively stained single particle specimens, those obtained by cryo-electron microscopy have the following new features: (a) higher “signal” variability due to a higher variability of particle orientation; (b) reduced signal/noise ratio (S/N); (c) virtual absence of low-spatial-frequency information related to elastic scattering, due to the properties of the phase contrast transfer function (PCTF); and (d) reduced resolution due to the efforts of the microscopist to boost the PCTF at low spatial frequencies, in his attempt to obtain recognizable particle images.

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Microstructure and reactivity of small metal particles: The role of Ce additives

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121995 ◽

1992 ◽

Vol 50 (1) ◽

pp. 318-319

Author(s):

L.D. Schmidt ◽

K. R. Krause ◽

J. M. Schwartz ◽

X. Chu

Keyword(s):

Atmospheric Pressure ◽

Noble Metals ◽

Mixed Oxides ◽

Catalytic Properties ◽

Chemical Shifts ◽

Catalytic Converter ◽

Structural Evolution ◽

Single Particles ◽

Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

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Structure of rattlesnake venom lectin determined by single particle high-resolution electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162776 ◽

1996 ◽

Vol 54 ◽

pp. 62-63

Author(s):

Peter D. Moisiuk ◽

Daniel R. Beniac ◽

Ross A. Ridsdale ◽

Martin Young ◽

Bhushan Nagar ◽

...

Keyword(s):

High Resolution Electron Microscopy ◽

Lipid Monolayer ◽

Outer Diameter ◽

X Ray Diffraction ◽

Single Particles ◽

Crotalus Atrox ◽

3D Reconstructions ◽

X Ray ◽

Rattlesnake Venom ◽

Covalently Linked

Venom from the rattlesnake Crotalus atrox contains a mixture of enzymes that induce a localized effect leading to hemorrhaging, necrosis and edema. As a member of the crotalid family of snake venoms, Crotalus atrox venom contains a C-type lectin that will agglutinate blood cells in a Ca2+-dependent fashion. The lectin is a hydrophilic protein, consisting of two covalently linked, 135 amino acid residues, identical subunits that are rich in aspartic acid, glutamic acid and lysine. Sequence homology with known carbohydrate recognition domains (CRDs) indicates that rattlesnake venom lectin (RSLV) contains a CRD motif that is not linked to accessory domains. Preliminary X-ray diffraction and sedimentation analysis has indicated that lectin from Crotalus atrox forms decamers composed of two five-fold symmetric pentamers. Single particles of RSVL imaged at – 171°C displayed two distinct orientations on the specimen support (Figure a) following incubation in a crystallization Teflon well, coated with a lipid monolayer consisting of phosphatidylcholine and monosialoganglioside. When lying in an end-on orientation, the lectin exhibited a “pentagonal ring” with an outer diameter of 6.7 nm and an inner hollow core of 1.7 nm. A side orientation was also seen, whereby a thickness of 5.8 nm was measured for the lectin. Image processing of 2280 single particles placed in 100 classes (Figure b) led to 3D reconstructions of RSVL (Figure c). Density limited 3D reconstructions showed the lectin to be made of two five-fold symmetrical rings covalently linked between the five subunits that constitute each ring of this homodimer. These results are consistent with sedimentation and preliminary X-ray diffraction analysis on the shape of RSVL and provide the framework for structural verification by 2D electron crystallography.

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Laser Oscillation in Aggregates of Ultrasmall Si Nanoparticles

MRS Proceedings ◽

10.1557/proc-728-s6.6 ◽

2002 ◽

Vol 728 ◽

Cited By ~ 1

Author(s):

Munir H. Nayfeh

Keyword(s):

Stimulated Emission ◽

Gaussian Beams ◽

Single Particles ◽

Nonlinear Characteristics ◽

Femtosecond Radiation ◽

Highly Nonlinear ◽

Line Narrowing ◽

Si Nanoparticles ◽

Speckle Patterns ◽

Spectral Line Narrowing

AbstractWe dispersed electrochemically etched Si into ultrabright ultrasmall nanoparticles, with brightness higher than fluorescein or rhodamine. The emission from single particles is readily detectable. Aggregates or films of the particles exhibit emission with highly nonlinear characteristics. We observe directed blue beams at ∼ 410 nm between faces of aggregates excited by femtosecond radiation at 780 nm; and at ∼ 610 nm from aggregates of red luminescent Si nanoparticles excited by radiation at 550-570 nm from a mercury lamp. Intense directed Gaussian beams, a pumping threshold, spectral line narrowing, and speckle patterns manifest the emission. The results are analyzed in terms of population inversion and stimulated emission in quantum confinement-induced Si-Si dimer phase, found only on ultrasmall Si nanoparticles. This microlasing constitutes an important step towards the realization of a laser on a chip.

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