Size Distribution Measurements Research Articles

Particle tracer analysis for PIV experiments in a closed loop transonic wind tunnel

A performance study of several tracer particles for PIV has been conducted. The study included particle response time analysis of an oblique shock wave generated by a conical nose of a store model in a closed loop transonic wind tunnel, and in-situ measurements of the particle size distribution in a low-speed wind tunnel facility. From the oblique shock wave analysis, the estimated particle response time for different smoke materials and generator settings was of the order of 1.4 - 2.2 μs and the effective particle size was 0.58 - 0.85 μm, which was much larger than the measured geometric mean particle size. This larger size was mainly attributed to the correlation bias towards larger particles in PIV measurements. The effective particle size from the particle response time analysis accounts for the holistic performance of the PIV system. Additionally, particle response analysis was performed on ambient water droplets resident in the tunnel. The estimated particle response time for the water droplets was in the order of 3.4 μs and the effective particle size was 0.97 μm, revealing inferior performance compared to the smoke particles.

Application Of The Phase Doppler Measurement Technique For The Characterization Of Supersonic Gas Atomization

A dual-mode phase Doppler measurement system has been set up for the characterization of the complex spray produced through supersonic gas atomization. The atomizer design has been based on a generic close-coupled configuration operated with water and air, which leads to high local Mach numbers and complex patterns of compression and expansion waves within the gas flow field. As a result, the dense spray is characterized by high particle velocities and a wide range of particle sizes, which proves challenging for experimental investigations. Measurements of local particle size and velocity distributions have been performed in various radial positions within the spray downstream of the atomizer, where the spray is fully developed. The set point of operation, which is defined by the gas stagnation pressure and the liquid mass flow rate, has been varied systematically, covering a wide range. By decoupling both operational parameters, their influence on the atomization result has been investigated independently. Furthermore, the atomizer geometry has been varied in terms of liquid nozzle diameter and liquid nozzle protrusion length. In accordance with data from the literature, the gas stagnation pressure has been observed to lead to decreasing median particle size and dispersion of the particle size, when increased. However, as a novel finding, the atomization result has been shown to be more sensitive to changes in the liquid mass flow rate. Thus, increasing the liquid mass flow rate results in an increase in both the median particle size and the dispersion of the particle size. The relationship between the atomization result and the gas-to-liquid ratio has been clearly shown to be ambiguous, that is, a function of the gas stagnation pressure and the liquid mass flow rate. Neither the liquid nozzle diameter nor the liquid nozzle protrusion length have been found to have an influence on the median particle size. However, the latter clearly influences the dispersion of the particle size in a complicated way, while the effect of the liquid nozzle diameter is more subtle. It has been concluded that the complex coupling between operational parameters and the specific atomizer design evident in supersonic gas atomization requires a deeper understanding of the local gas flow field and its interaction with the liquid flow.

Revisiting the Hail Radar Reflectivity–Kinetic Energy Flux Relation by Combining T-Matrix and Discrete Dipole Approximation Calculations to Size Distribution Observations

Abstract The retrieval of hail kinetic energy with weather radars or its simulation in numerical models is challenging because of the shape complexity and variable density of hailstones. We combine 3D scans of individual hailstones with measurements of the particle size distributions (PSD) and T-matrix calculations to understand how hail reflectivity Z changes when approximating hailstones as spheroids, as compared to the realistic shapes obtained by 3D scanning technology. Additionally, recent terminal velocity relations are used to compare Z to the hail kinetic energy flux . We parameterize the hail backscattering cross sections at L, S, C, and X bands as a function of size between 0.5 and 5.0 cm, matching the range of the observed PSDs. The scattering calculations use the T-matrix method for size parameters below 1.0 and the discrete dipole approximation (DDA) method otherwise. The DDA calculations are done for 48 digital models of realistic hailstones of sizes between 1 and 5 cm. The DDA cross sections are calculated for multiple orientations and averaged assuming a fully random orientation distribution to provide a single value per hailstone. The T-matrix reflectivity assuming solid ice spheres presents negligible differences to DDA results for size parameters below 1.0. Therefore, T matrix was used to fill in the gaps left by the DDA calculations. The results are mapped to the same size bins of the observed PSDs, allowing the calculation of the radar reflectivity. This is then correlated to , allowing a potential improvement of past retrieval methods of from Z in multiple wavelengths.

What determines the drop size in sprays of polymer solutions?

The effect of viscoelasticity on sprays produced from agricultural flat fan nozzles is investigated experimentally using dilute aqueous solutions of polyethylene oxide (PEO). Measurements of the droplet size distribution reveal that polymer addition to water results in the formation of overall bigger droplets with a broader size distribution. The median droplet size is found to increase linearly with the extensional relaxation time of the liquid and to be well captured by a simple empirical expression in terms of non-dimensional Weber and Deborah numbers. We show that the increase in droplet size with increasing viscoelasticity can be partly attributed to an increase of the wavelength of the flapping motion responsible for the sheet breakup, resulting in the formation of larger ligaments from which droplets are formed. We also show that droplet size distributions, rescaled by the average drop size, are well described by a compound gamma distribution with parameters n and m encoding for the ligament corrugation and the width of the ligament size distribution, respectively. These parameters are found to saturate to values n = 4 and m = 4 at sufficiently high polymer concentrations. • Viscoelasticity leads to larger droplets in sprays for agricultural flat fan nozzles. • Polymer additives can therefore be used to reduce airborne spray drift. • The median droplet size increases linearly with the extensional relaxation time. • Droplet sizes are Gamma distributed with broad drop and ligament sizes with polymers.

Grafted Pullulan Derivatives for Reducing the Content of Some Pesticides from Simulated Wastewater.

The goal of the current article was to obtain data regarding the application of a series of grafted pullulan derivatives, as flocculating agents, for removal of some pesticide formulations from model wastewater. The pullulan derivatives are cationic polyelectrolytes, with various content and length of grafted poly[(3-acrylamidopropyl)-trimethylammonium chloride] chains onto the pullulan (P-g-pAPTAC)]. The commercial pesticides are either fungicide (Bordeaux Mixture) (BM) or insecticides (Decis (Dc)—active ingredient Deltamethrin, Confidor Oil (CO)—active ingredient Imidacloprid, Confidor Energy (CE)—active ingredients Deltamethrin and Imidacloprid and Novadim Progress (NP)—active ingredient Dimethoate). The removal efficiency has been assessed by UV-Vis spectroscopy measurements as a function of some parameters, namely polymer dose, grafted chains content and length, pesticides concentration. The P-g-pAPTAC samples showed good removal efficacy at doseop, more than 94% for BM, between 84 and 90% for DC, CO and CE and around 93% for NP. The maximum percentage removal decreased with the pesticides (DC, CO, CE, NP) concentration declining; no effect of BM concentration in suspension on its removal efficiency process has been noted. Differences indicated by zeta potential and particle size distribution measurements regarding the pesticides removal mechanisms by pullulan derivatives (charge neutralization, bridging, etc.) are discussed.

Outdoor and indoor measurements of number particles size distributions and equivalent black carbon (EBC) at a mechanical manufacturing plant

Human exposure to air pollution is of great concern, especially in working places, where many people spend a lot of time. This work describes results obtained during a measurements campaign (February–July 2021) of aerosol number size distributions and equivalent black carbon (EBC), inside and outside a mechanical manufacturing plant, in Southern Italy. Outdoor and indoor EBC data are highly correlated (R2 = 0.98) suggesting the same sources: vehicular traffic, domestic heating and agricultural waste burning (February–April). In these months the outdoor Angstrom absorption exponent (AAE) was highly oscillating (0.64–1.62), with reduced oscillations (0.9–1.5) during warmer months. These last values suggest the influence of a diffuse cloud of aged smoke due to uncontrolled and extended wheat biomass burning, lasting about one month, in the nearby Apulia region. A good correlation between outdoor EBC and NC1 (particles number with D ≤ 1 μm) confirms that EBC has a high contribution to the aerosol size distribution. The same profile of number size distributions in both configurations indicates the same sources but, during cold months, the outdoor ones are characterized by higher values than the warm months, especially in the fine particles range. During working and non-working days, a reduction of indoor particles number concentration over the whole size range is observed throughout the weekend, suggesting manufacturing activities as one of the sources. Scanning electron microscope (SEM) analysis of outdoor and indoor spare internal filters shows the presence of metal particles indicating inside particles are being transported outside.

A dual-wavelength photothermal aerosol absorption monitor: design, calibration and performance

Abstract. There exists a lack of aerosol absorption measurement techniques with low uncertainties and without artefacts. We have developed the two-wavelength Photothermal Aerosol Absorption Monitor (PTAAM-2λ), which measures the aerosol absorption coefficient at 532 and 1064 nm. Here we describe its design, calibration and mode of operation and evaluate its applicability, limits and uncertainties. The 532 nm channel was calibrated with ∼ 1 µmol mol−1 NO2, whereas the 1064 nm channel was calibrated using measured size distribution spectra of nigrosin particles and a Mie calculation. Since the aerosolized nigrosin used for calibration was dry, we determined the imaginary part of the refractive index of nigrosin from the absorbance measurements on solid thin film samples. The obtained refractive index differed considerably from the one determined using aqueous nigrosin solution. PTAAM-2λ has no scattering artefact and features very low uncertainties: 4 % and 6 % for the absorption coefficient at 532 and 1064 nm, respectively, and 9 % for the absorption Ångström exponent. The artefact-free nature of the measurement method allowed us to investigate the artefacts of filter photometers. Both the Aethalometer AE33 and CLAP suffer from cross-sensitivity to scattering – this scattering artefact is most pronounced for particles smaller than 70 nm. We observed a strong dependence of the filter multiple scattering parameter on the particle size in the 100–500 nm range. The results from the winter ambient campaign in Ljubljana showed similar multiple scattering parameter values for ambient aerosols and laboratory experiments. The spectral dependence of this parameter resulted in AE33 reporting the absorption Ångström exponent for different soot samples with values biased 0.23–0.35 higher than the PTAAM-2λ measurement. Photothermal interferometry is a promising method for reference aerosol absorption measurements.

Fragmentation Size Distribution Measurement by GNSS-Aided Photogrammetry at Real Mine Site

In mining operations that employ explosives and mineral processing, one of the important factors for efficient and low-cost operation is the fragmentation size distribution of rock after it has been blasted. Automatic scaling is a critical component of fragmentation size distribution measurement as it will directly determine the accuracy of the size estimation. In this study, we propose a method to create a system for creating a scaled 3D CG model, without the use of ground truth data such as GCPs (Ground Control Points), for the purpose of improving fragmentation size distribution measurement using positional data such as GNSS (Global Navigation Satellite System)-aided photogrammetry. We confirmed the validation of the method through an experimental evaluation of actual muckpiles. The results showed evidence of improving the scaling aspect of 3D fragmentation measurement systems without using GCPs or manual scales, specifically in surface mines where GNSS data are available.

Carbon-based zero valent iron catalyst for NOX removal at low temperatures: performance and kinetic study.

In order to solve the problem of nitrous oxide (NOX) removal at low temperatures, the carbon-based zero valent iron (C-ZFe) catalyst was prepared and studied. According to the kinetic study and the obtained kinetic parameters, the De-NOX reactor was designed to provide information for industrial applications. The box-behnken experimental design (BBD) was used to study the performance of C-ZFe, and the optimized operating parameters were obtained as the temperature was 408.15K, the catalyst bed height was 140cm (the space velocity was 459h-1), the concentration of NO was 550ppm, under which the NOX conversion was 72.7%. A kinetic model based on Langmuir-Hinshelwood (L-H) and Mars Van Krevelen mechanism was used to describe the kinetics for the reduction of NO by C-ZFe at low temperatures. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), surface area and pore size distribution measurements, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results supported the validity of the model proposed. The gas-solid catalytic kinetic process of NO removal by C-ZFe was a quasi-first-order kinetic reaction, the apparent activation energy was 41.57kJ/mol, and the pre-exponential factor was 2980min-1.

Interferometric laser imaging for droplet-size measurement in spray.

An upgraded droplet-size measurement method, based on laser interference particle imaging (IPI) technology, is applied to accomplish high-precision measurement of particle size and spatial distribution of gas-liquid two-phase flow in the atomization field. In this study, an improved morphological-Hough transform interference fringe location algorithm is applied to IPI measurement. The particle size of the standard particle field with a diameter of 24 µm is measured by the upgraded IPI measurement experimentally, whose absolute error and relative error are 0.14 µm and 0.58%, respectively. The atomization field of the 400 µm centrifugal nozzle under different pressures is demonstrated by direct imaging and IPI technology, where the assessment results are evaluated by SMD value and particle size distribution, and the results exhibit good agreement.

Effect of Liquid–Liquid Interfacial Area on Biphasic Catalysis Exemplified by Hydroformylation

Biphasic catalysis enables the effective recycling of homogeneous catalysts by their immobilization in an additional liquid phase immiscible with the products. The introduced liquid–liquid interfacial area implies mass transfer limitations that play an important role in understanding these catalytic systems, with many rate enhancement strategies revolving around optimizing said area. In this contribution, the relationship between liquid–liquid interfacial area and catalytic activity is elucidated by applying a methodology that utilizes an image-based in situ measurement of the transient droplet size distribution. When the industrially highly relevant aqueous biphasic hydroformylation of the long-chain olefin 1-octene is taken as the model reaction, it is found that the product nonanal and the addition of the ligand increases the interfacial area by a factor of up to 5. The rate of conversion is found to depend on the stirring speed. By variation of the catalyst concentration, it is shown that an accumulation of the catalyst species at the interface is unlikely. Using a mathematical model, it is highlighted that the effect of the aqueous–organic interfacial area on the catalytic activity is not linear as was previously assumed in the literature. Instead, a change in the interfacial composition is proposed that causes a shift in the dependence of catalytic activity on said area. Thus, the dynamic physical properties of a lean gas–liquid–liquid system were linked to the catalytic performance of the system.

Sensitivity analysis of attenuation in convective rainfall at X-band frequency using the mountain reference technique

Abstract. The RadAlp experiment aims at improving quantitative precipitation estimation (QPE) in the Alps thanks to X-band polarimetric radars and in situ measurements deployed in the region of Grenoble, France. In this article, we revisit the physics of propagation and attenuation of microwaves in rain. We first derive four attenuation–reflectivity (AZ) algorithms constrained, or not, by path-integrated attenuations (PIAs) estimated from the decrease in the return of selected mountain targets when it rains compared to their dry weather levels (the so-called mountain reference technique – MRT). We also consider one simple polarimetric algorithm based on the profile of the total differential phase shift between the radar and the mountain targets. The central idea of the work is to implement these five algorithms all together in the framework of a generalized sensitivity analysis in order to establish useful parameterizations for attenuation correction. The parameter structure and the inherent mathematical ambiguity of the system of equations makes it necessary to organize the optimization procedure in a nested way. The core of the procedure consists of (i) exploring with classical sampling techniques the space of the parameters allowed to be variable from one target to the other and from one time step to the next, (ii) computing a cost function (CF) quantifying the proximity of the simulated profiles and (iii) selecting parameters sets for which a given CF threshold is exceeded. This core is activated for a series of values of parameters supposed to be fixed, e.g., the radar calibration error for a given event. The sensitivity analysis is performed for a set of three convective events using the 0∘ elevation plan position indicator (PPI) measurements of the Météo-France weather radar located on top of the Moucherotte mountain (altitude of 1901 m a.s.l. – above sea level). It allows the estimation of critical parameters for radar QPE using radar data alone. In addition to the radar calibration error, this includes the time series of radome attenuation and estimations of the coefficients of the power law models relating the specific attenuation and the reflectivity (A–Z relationship) on the one hand and the specific attenuation and the specific differential phase shift (A–Kdp relationship) on the other hand. It is noteworthy that the A–Z and A–Kdp relationships obtained are consistent with those derived from concomitant drop size distribution measurements at ground level, in particular with a slightly non-linear A–Kdp relationship (A=0.28 Kdp1.1). X-Band radome attenuations as high as 15 dB were estimated, leading to the recommendation of avoiding the use of radomes for remote sensing of precipitation at such a frequency.

Mapping riverbed sediment size from Sentinel‐2 satellite data

AbstractA comprehensive understanding of river dynamics requires the grain size distribution of bed sediments and its variation across different temporal and spatial scales. Several techniques are already available for grain size assessment based on field and remotely sensed data. However, the existing methods are only applicable on small spatial scales and on short time scales. Thus, the operational measurement of grain size distribution of riverbed sediments at the catchment scale remains an open problem. A solution could be the use of satellite images as the main imaging platform. However, this would entail retrieving information at sub‐pixel scales.In this study, we propose a new approach to retrieve sub‐pixel scale grain size class information from Copernicus Sentinel‐2 imagery building upon a new image‐based grain size mapping procedure. Three Italian gravel‐bed rivers featuring different morphologies were selected for unmanned aerial vehicle (UAV) acquisitions, field surveys and laboratory analysis meant to serve as ground truth grain size data, ranging from medium sand to coarse gravel. Grain size maps on the river bars were generated in each study site by exploiting image texture measurements, upscaled and co‐registered with Sentinel‐2 data resolution.Relationships between the grain sizes measured and the reflectance values in Sentinel‐2 imagery were analysed using a machine learning framework. Results show statistically significant predictive models (MAE of ±8.34 mm and R2 = 0.92). The trained model was applied on 300 km of the Po River in Italy and allowed us to identify the gravel–sand transition occurring along this river length.Therefore, the approach presented here—based on freely available satellite data calibrated by low‐cost drone‐derived imagery—represents a promising step towards an automated surface mean grain size mapping over long river length, easily repeated through time for monitoring purposes.

Exposure to Aerosols Emitted from Common Heating Combustion Sources Indoors—The Jordanian Case as an Example for Eastern Mediterranean Conditions

In Jordan, ~61% of total residential energy consumption is consumed by heating spaces using portable kerosene (K) and liquified petroleum gas (LPG) heaters. Here, we evaluated the indoor air quality (IAQ) versus the use of K and LPG heaters inside a test room reflecting the typical conditions of Jordanian dwellings during the winter season. The experimental setup included particle size distribution (diameter 0.01–25 µm) measurements, and we utilized a simple sectional indoor aerosol model (SIAM) to estimate the emission rate and lifetime of the combustion products in the test room. The particle number (PN) concentration during the LPG operation was 6 × 104–5.9 × 105 cm−3, depending on the setting at minimum, medium, or maximum. The K heater operation increased with the PN concentrations to a range of 4 × 105–8 × 105 cm−3. On average, the particle losses were 0.7–1.6 h−1 for micron particles (1–10 µm) and 0.8–0.9 h−1 for ultrafine particles (<0.1 µm). The emission rate from the LPG heater was 1.2 × 1010–2.8 × 1010 particles/s (6.6 × 106–8.0 × 106 particles/J), and that for the K heater was about 4.4 × 1010 particles/s (1.9 × 107 particles/J). The results call for the immediate need to apply interventions to improve the IAQ by turning to cleaner heating processes indoors.

Effect of oxymethylene ether-2-3-4 (OME2-4) on soot particle formation and chemical features

The reduction of carbon emissions is leading to alternative and renewable energy sources. Solar or wind sources can only be regulated to a limited extent and fluctuate considerably due to environmental conditions, which could be overcome by chemical energy storage solutions.Synthetic fuels are chemical energy carriers that can be produced using excess renewable electrical energy and can be directly used or easily stored. Different synthetic fuels have been investigated recently as a potential alternative or additive for fossil diesel and gasoline. Of the synthetic fuels, oxymethylene ethers (OMEs) have proven to be suitable candidates for compression-ignition engines while additionally reducing soot emissions when used either as a neat fuel or blended with fossil fuels. However, the effect of varying OME chain length on this soot reduction effect and the structure of the particulate matter has not yet been systematically investigated.This study therefore compares the soot reduction potential and analyzes the physicochemical particle features in laminar premixed flames fueled with pure ethylene and ethylene/OME2-4 flames at four equivalence ratios, from lightly to heavily sooting conditions. Particle size distribution (PSD) measurements and numerical investigations (Conditional Quadrature Method of Moments—CQMOM) were conducted to study particle formation and growth. The results indicate a reduction in the total number and size of particles at all equivalence ratios, while the number of nanoparticles remains almost unchanged. The CQMOM model predicts the general shape of the experimentally measured PSD for both ethylene and OME-blended flames. Further, carbon particulate matter was thermophoretically sampled and its chemical structure was analyzed. The nanostructure of soot was investigated using ultraviolet–visible and Raman spectroscopy, revealing slightly higher aromaticity for the pure ethylene soot, whereas OME2-4 particles exhibited increased reactivity, as evidenced by thermogravimetric analysis. Fourier-Transform Infrared (FTIR) spectroscopy analysis showed that carbon particulate matter produced from OME2-4-doped flames contained higher amounts of oxygen, mainly as C = O. Mass spectrometry confirmed the presence of oxygen-containing functional groups in OME2-4 particulate only.

Spray characteristics from nasal spray atomization

In addition to topical delivery, nasal sprays offer an alternative drug administration route to the systemic circulation, therefore avoiding the need for painful, invasive delivery techniques. Studies on the efficacy of nasal drug delivery to date have been conflicting despite its potential. In particular computational studies, e.g. Computational Fluid Dynamics (CFD), of nasal spray deposition require realistic initial spray conditions, which are lacking in the literature. This study aims to provide benchmark experimental data for CFD inputs by characterizing four different types of commercially available nasal sprays used in an ENT (Ear Nose Throat) clinic. Spray characteristics were obtained via high-speed videography, while droplet size distribution (DSD) measurements were obtained with laser diffraction. Three actuation forces were evaluated, representing the use-case of an average adult, average child and the maximum force applied to the spray device. The results demonstrated that actuation force influenced spray velocity, spray duration, DSD, and breakup length. Quantitative data of Rosin–Rammler diameter distributions, spray cone angles, dispersion angles and breakup lengths were found, assisting computational models with realistic values, thereby improving future CFD studies of nasal spray drug delivery in the nasal cavity.

In-situ imaging of particle size distribution in an industrial-scale calcination reactor using micro-focusing particle shadowgraphy

We present a novel demonstration of in-situ particle size measurement in a high-temperature, industrial-scale reactor for lime-calcination using micro-focusing particle shadowgraphy in particle-laden flows with volume fraction up to 0.02 and an optical path length of 670 mm. This non-intrusive method was demonstrated to provide reliable in-situ measurement of both particle size distribution (PSD) and sphericity, which are relevant to the performance of a novel cement production technology under development to provide direct capture of process-derived CO2 emissions. The details of the optical diagnosing system and test rig are presented. A previously reported processing algorithm based on image gradient to accurately identify the edges of particles in the focal plane with negligible line-of-sight interference was employed to derive both particle diameter and sphericity in comparison with independent extractive measurements with a commercial Mastersizer. The in-situ measurement revealed the presence of large calcined particle agglomerates under some conditions that were not identified with the extractive measurements. Statistical correlations between particle diameter and sphericity are also reported.

Measurement report: Interpretation of wide-range particulate matter size distributions in Delhi

Abstract. Delhi is one of the world's most polluted cities, with very high concentrations of airborne particulate matter. However, little is known about the factors controlling the characteristics of wide-range particle number size distributions. Here, new measurements are reported from three field campaigns conducted in winter and pre-monsoon and post-monsoon seasons at the Indian Institute of Technology campus in the south of the city. Particle number size distributions were measured simultaneously, using a scanning mobility particle sizer and a GRIMM optical particle monitor, covering 15 nm to >10 µm diameter. The merged, wide-range size distributions were categorized into the following five size ranges: nucleation (15–20 nm), Aitken (20–100 nm), accumulation (100 nm–1 µm), large fine (1–2.5 µm), and coarse (2.5–10 µm) particles. The ultrafine fraction (15–100 nm) accounts for about 52 % of all particles by number (PN10 is the total particle number from 15 nm to 10 µm) but just 1 % by PM10 volume (PV10 is the total particle volume from 15 nm to 10 µm). The measured size distributions are markedly coarser than most from other parts of the world but are consistent with earlier cascade impactor data from Delhi. Our results suggest substantial aerosol processing by coagulation, condensation, and water uptake in the heavily polluted atmosphere, which takes place mostly at nighttime and in the morning hours. Total number concentrations are highest in winter, but the mode of the distribution is largest in the post-monsoon (autumn) season. The accumulation mode particles dominate the particle volume in autumn and winter, while the coarse mode dominates in summer. Polar plots show a huge variation between both size fractions in the same season and between seasons for the same size fraction. The diurnal pattern of particle numbers is strongly reflective of a road traffic influence upon concentrations, especially in autumn and winter, although other sources, such as cooking and domestic heating, may influence the evening peak. There is a clear influence of diesel traffic at nighttime, when it is permitted to enter the city, and also indications in the size distribution data of a mode < 15 nm, which is probably attributable to CNG/LPG vehicles. New particle formation appears to be infrequent and is, in this dataset, limited to 1 d in the summer campaign. Our results reveal that the very high emissions of airborne particles in Delhi, particularly from traffic, determine the variation in particle number size distributions.

The Impact of Exosomes/Microvesicles Derived from Myeloid Dendritic Cells Cultured in the Presence of Calcitriol and Tacalcitol on Acute B-Cell Precursor Cell Lines with MLL Fusion Gene.

Vitamin D analogs (VDAs) may directly inhibit the growth of normal and malignant (derived from acute lymphoblastic leukemia (ALL)) B cells, as both types of cells express vitamin D receptor (VDR). We performed anti-proliferative, morphology tests and phenotyping to evaluate the sensitivity of monocytes and iDCs (immature myeloid-derived dendritic cells) on calcitriol and tacalcitol treatment, phenotyping, morphology, and size distribution measurement to determine the characteristics of microvesicles (MVs) and exosomes (EXs) derived from them and, finally, phenotyping and Elisa test to determine the effects of VDAs on modulation of the phenotype of B cells through extracellular vesicles (EVs) released by iDCs. Our results confirmed that both SC cells and iDCs were sensitive to the VDAs and showed altered surface expression of markers associated with monocyte differentiation, which was resulting in the phenotypic changes in EVs derived from them. We also showed that obtained EVs could change the morphology and phenotype of ALL-B-derived precursor cells in a different way, depending on their origin. The differential effect of VDAs on ALL-B cells, which was associated with increased or decreased expression of CD27, CD24, CD38, and CD23 expression, was observed. Hence, further studies to explain the modulation in the composition of EVs by VDAs are required.

Saharan Dust Deposition in Central Europe in 2016—A Representative Year of the Increased North African Dust Removal Over the Last Decade

Changes in circulation patterns associated with climate change have led to an increase in the frequency and intensity of Saharan dust events (SDEs) in the Carpathian Basin. The annual number of dust events was 4.2 on average between 1979 and 2010, while in the period of 2011–2018, it has increased to 10.3. This study presents a quantitative assessment of wet deposition of dust particles to Lake Balaton (Central Europe) with mineralogical and particle size distribution measurements. In addition to a comprehensive, systematic SDE identification process, rainwater samples were collected in 2016, and the particles on the filters were characterised using a range of analytical techniques. The atmospheric transport of particulates and moisture was evaluated using HYSPLIT Lagrangian trajectory model. XRD measurements revealed that during these events, the major minerals were quartz, kaolinite and 10-Å phyllosilicates. In addition, mineralogical source markers of arid dust (palygorskite and smectite) were also identified in majority of the analysed samples. Based on the results, wet deposition fluxes of dust particles were estimated for the region. 2016 was a typical and representative year for the decade, with twelve identified dust episodes. The synoptic patterns of the events fit well with the typical meteorological character of the North African dust intrusions with enhanced atmospheric meridionality described earlier. From the twelve episodes of 2016, seven were depositional events when wet deposition could be observed at ground level. Dust material of five episodes was analysed in detail, while particles of the two February wet deposition episodes were only granulometrically characterised. General uncertainties that hinder the characterisation of mineral dust in climate models were also observed in the granulometric and dust flux data of the sampled material. The particle size of the deposited dust was coarser than the upper cut-off level of grain size of the models. In addition, the discrepancies between measured and simulated deposition values clearly demonstrated the incorrect representation of dust flux in numerical simulations (partly due to inaccurate grain size data in the models).