Identification of key aerosol types and mixing states in the central Indian Himalayas during the GVAX campaign: the role of particle size in aerosol classification

Abstract. Characterizing chemical and physical aerosol properties is important to understand their sources, effects, and feedback mechanisms in the atmosphere. This study proposes a scheme to classify aerosol populations based on their spectral optical properties (absorption and scattering). The scheme is obtained thanks to the outstanding set of information on particle size and composition these properties contain. The spectral variability of the aerosol Single Scattering Albedo (dSSA), and the Scattering and Absorption Angstrom Exponents (SAE and AAE, respectively) were observed on the basis of two-year measurements of aerosol optical properties (scattering and absorption coefficients at blue, green and red wavelengths) performed in the suburbs of Rome (Italy). Optical measurements of various aerosol types were coupled to measurements of particle number size distributions and relevant optical properties simulations (Mie theory). These latter allowed to investigate the role of the particle size and composition in the bulk aerosol properties observed. The combination of simulations and measurements suggested a general "paradigm" built on dSSA, SAE and AAE to optically classify aerosols. The paradigm proved suitable to identify the presence of key aerosol populations, including soot, biomass burning, organics, dust and marine particles. The work highlights that: (i) aerosol populations show distinctive combinations of SAE and dSSA times AAE, these variables being linked by a linear inverse relation varying with varying SSA; (ii) fine particles show SAE > 1.5, whilst SAE < 1 is found for both coarse particles and ultrafine soot-rich aerosols; (iii) fine and coarse particles both show SSA > 0.8, whilst ultrafine urban Aitken mode and soot particles show SSA < 0.8. A strict agreement was found when comparing the proposed paradigm to aerosol observations performed during past major field campaigns.

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Fibrin Formation: The Role of the Fibrinogen-Fibrin Monomer Complex

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648007 ◽

1976 ◽

Vol 36 (01) ◽

pp. 037-048 ◽

Cited By ~ 49

Author(s):

Eric P. Brass ◽

Walter B. Forman ◽

Robert V. Edwards ◽

Olgierd Lindan

Keyword(s):

Particle Size ◽

Induction Period ◽

Fibrin Clot ◽

Clot Formation ◽

Appreciable Amount ◽

Buffer System ◽

Homeostatic Mechanism ◽

Fibrin Formation ◽

Fibrin Monomer

SummaryThe process of fibrin formation using highly purified fibrinogen and thrombin was studied using laser fluctuation spectroscopy, a method that rapidly determines particle size in a solution. Two periods in fibrin clot formation were noted: an induction period during which no fibrin polymerization occurred and a period of rapid increase in particle size. Direct measurement of fibrin monomer polymerization and fibrinopeptide release showed no evidence of an induction period. These observations were best explained by a kinetic model for fibrin clot formation incorporating a reversible fibrinogen-fibrin monomer complex. In this model, the complex serves as a buffer system during the earliest phase of fibrin formation. This prevents the accumulation of free polymerizable fibrin monomer until an appreciable amount of fibrinogen has reacted with thrombin, at which point the fibrin monomer level rises rapidly and polymerization proceeds. Clinically, the complex may be a homeostatic mechanism preventing pathological clotting during periods of elevated fibrinogen.

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272. Controlling Respirable Quartz Dust in Sand-Blasting: Role of Sand Particle Size and a Dust Suppression Agent

10.3320/1.2765800 ◽

2001 ◽

Author(s):

J. Nelson ◽

S. Soderholm ◽

M. Greskevitch

Keyword(s):

Particle Size ◽

Sand Particle ◽

Dust Suppression ◽

Sand Blasting ◽

Quartz Dust

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Faculty Opinions recommendation of The role of the particle size spectrum in estimating POC fluxes from disequilibrium.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1087095.540074 ◽

2007 ◽

Author(s):

Edward Laws

Keyword(s):

Particle Size ◽

Size Spectrum

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Positive Role of Synthesis Method and Hard Template on the Catalytic Performance of SAPO-34 in Methanol to Olefin Reaction.

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323666200720103321 ◽

2020 ◽

Vol 23 ◽

Author(s):

Sajjad Rimaz ◽

Reza Katal

Keyword(s):

Particle Size ◽

Synthesis Method ◽

Catalytic Performance ◽

Hard Template ◽

Structure Directing Agent ◽

Positive Role ◽

Methanol To Olefin ◽

Dg Method ◽

Synthesis Procedure

: In the present study, SAPO-34 particles were synthesized using hydrothermal (HT) and dry gel (DG) conversion methods in the presence of diethyl amine (DEA) as an organic structure directing agent (SDA). Carbon nanotubes (CNT) were used as hard template in the synthesis procedure to introduce transport pores into the structures of the synthesized samples. The synthesized samples were characterized with different methods to reveal effects of synthesis method and using hard template on their structure and catalytic performance in methanol to olefin reaction (MTO). DG conversion method results in smaller particle size in comparison with hydrothermal method, resulting in enhancing catalytic performance. On the other side, using CNT in the synthesis procedure with DG method results in more reduction in particle size and formation of hierarchical structure which drastically improves catalytic performance.

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Effect of grain size on the vapour phase hydration of monoclinic and triclinic modifications of tricalcium silicate; role of high temperature activation

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19911993 ◽

1991 ◽

Vol 56 (10) ◽

pp. 1993-2008

Author(s):

S. Hanafi ◽

G. M. S. El-Shafei ◽

B. Abd El-Hamid

Keyword(s):

Particle Size ◽

Vapour Phase ◽

Tricalcium Silicate ◽

Active Centers ◽

Thermally Activated ◽

Grain Sizes ◽

Intermediate Size ◽

Surface Active ◽

Temperature Activation

The hydration of tricalcium silicate (C3S) with three grain sizes of monoclinic (M) and triclinic (T) modifications and on their thermally activated samples were investigated by exposure to water vapour at 80°C for 60 days. The products were investigated by XRD, TG and N2 adsorption. The smaller the particle size the greater was the hydration for both dried and activated samples from (M). In the activated samples a hydrate with 2θ values of 38.4°, 44.6° and 48.6° could be identified. Hydration increased with particle size for the unactivated (T) samples but after activation the intermediate size exhibited enhanced hydration. Thermal treatment at 950°C of (T) samples increased the surface active centers on the expense of those in the bulk. Changes produced in surface texture upon activation and/or hydration are discussed.

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Investigating the Feasibility of Mefenamic Acid Nanosuspension for Pediatric Delivery: Preparation, Characterization, and Role of Excipients

Processes ◽

10.3390/pr9040574 ◽

2021 ◽

Vol 9 (4) ◽

pp. 574

Author(s):

Nikhat Perween ◽

Sultan Alshehri ◽

T. S. Easwari ◽

Vivek Verma ◽

Md. Faiyazuddin ◽

...

Keyword(s):

Particle Size ◽

Mefenamic Acid ◽

Hydroxypropyl Methylcellulose ◽

Sodium Dodecyl ◽

Aqueous Solubility ◽

Oral Route ◽

Precipitation Method ◽

Antisolvent Precipitation

Molecules with poor aqueous solubility are difficult to formulate using conventional approaches and are associated with many formulation delivery issues. To overcome these obstacles, nanosuspension technology can be one of the promising approaches. Hence, in this study, the feasibility of mefenamic acid (MA) oral nanosuspension was investigated for pediatric delivery by studying the role of excipients and optimizing the techniques. Nanosuspensions of MA were prepared by adopting an antisolvent precipitation method, followed by ultrasonication with varying concentrations of polymers, surfactants, and microfluidics. The prepared nanosuspensions were evaluated for particle size, morphology, and rheological measures. Hydroxypropyl methylcellulose (HPMC) with varying concentrations and different stabilizers including Tween® 80 and sodium dodecyl sulfate (SLS) were used to restrain the particle size growth of the developed nanosuspension. The optimized nanosuspension formula was stable for more than 3 weeks and showed a reduced particle size of 510 nm with a polydispersity index of 0.329. It was observed that the type and ratio of polymer stabilizers were responsive on the particle contour and dimension and stability. We have developed a biologically compatible oral nanoformulation for a first-in-class drug beautifully designed for pediatric delivery that will be progressed toward further in vivo enabling studies. Finally, the nanosuspension could be considered a promising carrier for pediatric delivery of MA through the oral route with enhanced biological impact.

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