scholarly journals Size distribution of particle-associated polybrominated diphenyl ethers (PBDEs) and their implications for health

2016 ◽  
Vol 9 (3) ◽  
pp. 1025-1037 ◽  
Author(s):  
Yan Lyu ◽  
Tingting Xu ◽  
Xiang Li ◽  
Tiantao Cheng ◽  
Xin Yang ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Polybrominated Diphenyl Ethers ◽  
Fine Particles ◽  
Bimodal Distribution ◽  
Urban Site ◽  
Deposition Flux ◽  
Human Respiratory Tract ◽  
Particle Size Range ◽  
Peak Intensity

Abstract. In order to better understand the size distribution of particle-associated PBDEs and their deposition pattern in the human respiratory tract, we carried out a 1-year campaign during 2012–2013 for the measurement of size-resolved particles at the urban site of Shanghai. The results showed that particulate PBDEs exhibited a bimodal distribution with a mode peak in the accumulation particle size range and the second mode peak in the coarse particle size ranges. As the number of bromine atoms in the molecule increases, accumulation-mode peak intensity increased while coarse-mode peak intensity decreased. This change was consistent with the variation of PBDEs' subcooled vapor pressure. Absorption and adsorption processes dominated the distribution of PBDEs among the different size particles. The evaluated deposition flux of Σ13 PBDEs was 26.8 pg h−1, in which coarse particles contributed most PBDEs in head and tracheobronchial regions, while fine-mode particles contributed major PBDEs in the alveoli region. In association with the fact that fine particles can penetrate deeper into the respiratory system, fine-particle-bound highly brominated PBDEs can be inhaled more deeply into human lungs and cause a greater risk to human health.

scholarly journals Particle-size distribution of polybrominated diphenyl ethers (PBDEs) and its implications for health

2015 ◽  
Vol 8 (12) ◽  
pp. 12955-12992 ◽  
Author(s):  
Y. Lyu ◽  
T. Xu ◽  
X. Li ◽  
T. Cheng ◽  
X. Yang ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Polybrominated Diphenyl Ethers ◽  
Fine Particles ◽  
Urban Site ◽  
Deposition Flux ◽  
Human Respiratory Tract ◽  
Particle Size Range ◽  
Peak Intensity

Abstract. In order better to understand the particle-size distribution of particulate PBDEs and their deposition pattern in human respiratory tract, we made an one year campaign 2012–2013 for the measurement of size-resolved aerosol particles at Shanghai urban site. The results showed that particulate PBDEs exhibited a bimodal distribution with a mode peak in the accumulation particle size range and the second mode peak in the coarse particle size ranges. As the number of bromine atoms in the molecule increased, accumulation mode peak intensity increased while coarse mode peak intensity decreased. This change was the consistent with the variation of PBDEs' sub-cooled vapor pressure. Absorption and adsorption process dominated the distribution of PBDEs among the different size particles. Evaluated deposition flux of Σ13PBDE was 26.8 pg h−1, in which coarse particles contributed most PBDEs in head and tracheobronchial regions, while fine mode particles contributed major PBDEs in the alveoli region. In associated with the fact that fine particles can penetrate deeper into the respiratory system, fine particle-bound highly brominated PBDEs can be inhaled more deeply into human lungs and cause a greater risk to human health.

Size distribution and sources of humic-like substances in particulate matter at an urban site during winter

2016 ◽  
Vol 18 (1) ◽  
pp. 32-41 ◽  
Author(s):  
Seungshik Park ◽  
Se-Chang Son
Keyword(s):  
Particle Size ◽  
Particulate Matter ◽  
Size Distribution ◽  
Bimodal Distribution ◽  
Asian Dust ◽  
Urban Site

The highest contribution of HULIS-C to WSOC was observed to be in the particle size bins of 0.55–1.0 μm and 1.8–3.1 μm during non-Asian dust (NAD, 45 ± 6%) and Asian dust (AD, 44 ± 7%) periods, respectively. HULIS exhibited a uni-modal (@0.55 μm) distribution during the NAD and a bimodal distribution (@0.32 and 1.8 μm) during AD, respectively.

scholarly journals Monte Carlo simulation for soot dynamics

2012 ◽  
Vol 16 (5) ◽  
pp. 1391-1394 ◽  
Author(s):  
Kun Zhou
Keyword(s):  
Particle Size ◽  
Monte Carlo ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Gas Phase ◽  
Volume Fraction ◽  
Soot Formation ◽  
Bimodal Distribution ◽  
Number Density ◽  
Stochastic Error

A new Monte Carlo method termed Comb-like frame Monte Carlo is developed to simulate the soot dynamics. Detailed stochastic error analysis is provided. Comb-like frame Monte Carlo is coupled with the gas phase solver Chemkin II to simulate soot formation in a 1-D premixed burner stabilized flame. The simulated soot number density, volume fraction, and particle size distribution all agree well with the measurement available in literature. The origin of the bimodal distribution of particle size distribution is revealed with quantitative proof.

scholarly journals Blend of natural waxes as a matrix for aroma encapsulation

2017 ◽  
Vol 15 (2) ◽  
pp. 103-111
Author(s):  
Jelena Milanovic ◽  
Gordana Ilic-Sevic ◽  
Marijana Gavrilovic ◽  
Milutin Milosavljevic ◽  
Branko Bugarski
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Elevated Temperatures ◽  
Thermal Characteristics ◽  
Feed Additives ◽  
Morphological Properties ◽  
Particle Size Range ◽  
Carnauba Wax ◽  
Potential Applications

In this study, the possibility of using a blend of natural waxes (bees and carnauba) for encapsulation of some aroma compounds was investigated. Melt dispersion/melt solidification technique was applied for microbeads production. Since one of the most important characteristics of the particles are the size and shape, particle size distribution as well as morphological properties are tested. Thermal characteristics are also examined as significant properties for thermal behavior at elevated temperatures, important for application of encapsulated particles in food production processes. Different contents of the carnauba wax in the mixture with beeswax are investigated, from 10% to 50% (w/w). Since one of the potential applications of the encapsulated aroma is in feed additives production, the targeted particle size range was under 300 ?m to be suitable for handling and mixing with other powder substances. According to the obtained results, a higher carnauba wax content in the wax blend had an impact on particle size distribution. Also, it had an impact on the surface morphology and thermal properties. The obtained results may contribute to the development of methods of encapsulation of hydrophobic aromas in the natural wax matrix.

scholarly journals Particle size-dependent fluorescence properties of water-soluble organic compounds (WSOC) and their atmospheric implications on the aging of WSOC

2021 ◽  
Author(s):  
Juanjuan Qin ◽  
Jihua Tan ◽  
Xueming Zhou ◽  
Yanrong Yang ◽  
Yuanyuan Qin ◽  
...  
Keyword(s):  
Particle Size ◽  
Organic Compounds ◽  
Fine Particles ◽  
Stokes Shift ◽  
Bimodal Distribution ◽  
Dominant Mode ◽  
Water Soluble ◽  
Atmospheric Particle ◽  
Humification Degree ◽  
Transformation Processes

Abstract. Water-soluble organic compounds (WSOC) are essential in atmospheric particle formation, migration, and transformation processes. Size-segregated atmospheric particles were collected in a rural area of Beijing. Excitation-emission matrix (EEM) fluorescence spectroscopy was used to investigate the sources and optical properties of WSOC. Sophisticated data analysis on EEM data was performed to characteristically estimate the underlying connections among aerosol particles in different sizes. The WSOC concentrations and average fluorescence intensity (AFI) showed monomodal distribution in winter and bimodal distribution in summer, with dominant mode between 0.26 to 0.44 µm for both seasons. The EEM spectra of size-segregated WSOC were different among variant particle sizes, which could be the results of changing sources and/or chemical transformation of organics. Size distributions of fluorescence regional intensity (region Ⅲ and Ⅴ) and HIX indicate that humification degree or aromaticity of WSOC was highest between 0.26 to 0.44 µm. The Stokes shift (SS) and the harmonic mean of the excitation and emission wavelengths (WH) reflected that π-conjugated systems were high between 0.26 to 0.44 µm as well. The parallel factor analysis (PARAFAC) results showed that humic-like substances were abundant in fine particles (< 1 µm) and peaked at 0.26–0.44 µm. All evidence supported that the humification degree of WSOC increased in submicron mode (< 0.44 µm) and decreased gradually. Thus, it was conjectured that condensation of organics still goes on in submicron mode, resulting in the highest humification degree exhibit in particle size between 0.26 to 0.44 µm rather than < 0.26 µm. Synthetically analyzing 3-dimensional fluorescence data could efficiently present the secondary transformation processes of WSOC.

The Role of Particle Size Distribution in the Performance and Modelling of Filtration

1993 ◽  
Vol 27 (10) ◽  
pp. 19-34 ◽  
Author(s):  
R. I. Mackie ◽  
R. Bai
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Coarse Particles ◽  
Large Particles

The paper examines the importance of size distribution of the influent suspension on the performance of deep bed filters and its significance with regard to modelling. Experiments were carried out under a variety of conditions using suspensions which were identical in every respect apart from their size distribution. The results indicate that the presence of coarse particles does increase the removal of fine particles. Deposition of fine particles leads to a greater headloss than deposition of large particles. Changes in size distribution with time and depth play an important role in determining the behaviour of a filter, and models of both removal and headloss development must take account of this.

A Noise Removal Method in Measurement of Particle Size Distribution by the Shifrin-Transform

2014 ◽  
Vol 1058 ◽  
pp. 93-96 ◽  
Author(s):  
Yue Han ◽  
Zong Ling Yang ◽  
Yin Nan Yuan ◽  
Bing Dai
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Large Angle ◽  
Bimodal Distribution ◽  
Noise Removal ◽  
Good Effect ◽  
Actual Measurement ◽  
Original Distribution ◽  
Angle Data

In actual measurement of particle size distribution by the Shifrin-transform, many noises are easily misread as distribution peaks, and bring serious difficulties to the measurement. The purpose of this paper is to find a method of removing these noises to improve existing technology. By analyzing the source of these noises, we found these noises are mainly caused by the serious large angle data loss, and then propose a compensation function in the Shifrin-transform to remove these noises. Simulations explain that the method has a good effect. The method is actually tested for the sample particles of the unimodal and bimodal distribution by experiments. The result shows that the noises disappear but the number and location of original distribution peaks aren’t affected after using the compensate function. So this method can remove effectively noises and restore accurately original distribution in the measurement.

Performance Characteristics of Centrifugal Slurry Pumps

2001 ◽  
Vol 123 (2) ◽  
pp. 271-280 ◽  
Author(s):  
B. K. Gandhi ◽  
S. N. Singh ◽  
V. Seshadri
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Performance Characteristics ◽  
Solid Concentration ◽  
Solid Materials ◽  
Power Characteristics ◽  
Additional Losses

The performance of two centrifugal slurry pumps has been reported for three solid materials having different particle size distribution (PSD) in terms of head, capacity, and power characteristics. The results have shown that the values of head and efficiency ratios are not only dependent on solid concentration but are also affected by PSD of the solids and properties of the slurry. The addition of fine particles in the slurry of coarser material leads to reduction in the additional losses that occur in the pumps due to the presence of solids. It is also observed that with the increase in the pump size, the additional losses due to presence of solids reduce.

Particle Size Distribution Measurement of Free-Falling Fine Particles in a Dusty Plasma Experiment

2001 ◽  
Vol 40 (Part 1, No. 5A) ◽  
pp. 3433-3434
Author(s):  
Nobuki Kawashima ◽  
Kazuya Takeda ◽  
Takeharu Etoh ◽  
Kousei Takehara ◽  
Haruya Kubo ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Dusty Plasma ◽  
Fine Particles ◽  
Distribution Measurement ◽  
Plasma Experiment ◽  
Particle Size Distribution Measurement ◽  
Free Falling

Reconstructed expression for aerosol extinction coefficient by considering mass extinction efficiency and hygroscopic growth for polydipersed aerosol

2020 ◽  
Author(s):  
Chang Hoon Jung ◽  
JiYi Lee ◽  
Junshik Um ◽  
Yong Pyo Kim
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Growth Factor ◽  
Size Distribution ◽  
Enhancement Factor ◽  
Size Range ◽  
Geometric Mean ◽  
Mie Theory ◽  
Hygroscopic Growth ◽  
Particle Size Range

&lt;p&gt;In this study, simplified analytic type of expression for size dependent MEs (Mass efficiencies) are developed. The entire size was considered assuming lognormal size distribution for sulfate, nitrate and NaCl aerosol species and the MEE of each aerosol chemical composition was estimated by fitting Mie&amp;#8217;s calculation. The obtained results are compared with the results from the Mie-theory-based calculations and showed comparable results.&lt;/p&gt;&lt;p&gt;The mass efficiencies of all aerosol components for each size range are compared with Mie&amp;#8217;s results and approximated as a function of geometric mean diameter in the form of a power law formula. Finally, harmonic mean type approximation was used to cover entire particle size range.&lt;/p&gt;&lt;p&gt;Also, analytic expression of approximated scattering enhancement factor which stands for the effect of hygroscopic growth factor for polydispersed aerosol on aerosol optical properties are obtained.&lt;/p&gt;&lt;p&gt;Based on aerosol thermodynamic models, mass growth factor can be obtained and their optical properties can be obtained by using Mie theory with different aerosol properties and size distribution. Finally, scattering enhancement factor was approximated fRH for polydispersed aerosol as a function of RH.&lt;/p&gt;&lt;p&gt;Finally, we also compared the simple forcing efficiency (SFE, W/g) of polydisperse aerosols between the developed simple approach and by the method using the Mie theory. The results show that current obtained approximated methods are comparable with existing numercal calculation based results for polydipersed particle size.&lt;/p&gt;

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