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The impact on indoor air quality during metal casting processes using the 3D printing (3DP) binder jetting technique to manufacture moulds is analyzed in this research. This study investigates the particle size distribution and gas concentration during the manufacturing stages of 3DP moulds, with focus on particle deposition in the human respiratory system. The goal is to understand the risks associated with particle and gas emissions in binder jetting 3D printing, and thus improve worker safety. The results indicate that particle emission rates are lowest during printing (0.01 1011particles min−1) but increase during post-processing and melting-pouring phases (3.07 1011 particles min−1). During melting and pouring, the emission of particles was mainly in the range 7.9–71 nm, with values 10 times higher than in the previous phases. The study calculates the deposition of inhaled particles in different parts of the respiratory tract and reveals a 2.39 times higher extrathoracic mass deposition during 3DP mould manufacturing stages compared to melting-pouring stages. Additionally, alveolar mass deposition is higher during melting-pouring stages due to an increase in ultrafine emission rates. The study emphasizes the importance of insulation equipment and workplace ventilation in indoor spaces, particularly during heating processes that generate ultrafine particles through nucleation, so that health risks can be mitigated. [Display omitted] • Particle size distributions were studied during metal casting using 3D print binder jetting. • Inhaled particle deposition rates in respiratory tracts were modelled. • Particle emission rates were lowest when printing, but rose in melting-pouring process. • During melting-pouring, the particle emission was mainly in the range 8–71 nm. • Alveolar mass deposition estimated was higher during melting-pouring stages. [ABSTRACT FROM AUTHOR]

Abstract Aerosol black carbon (BC) is the second strongest contributor to global warming, after CO 2 , and it is linked to many adverse health effects. A sampling campaign of 15 months was carried out in León (Spain) in order to evaluate the scavenging of BC with an ensemble aethalometer-disdrometer. The aethalometer provides the concentration of equivalent black carbon (eBC), and the disdrometer, the raindrop size distribution. A total of seventy-five rain events were studied and in 73% of them there was an effective (eBC initial > eBC final) scavenging, with a mean decrease of 48 ± 37% in long rain events (>8 h) and 39 ± 38% in short rain events. The scavenging of BC is strongly related to its source. Thus, the scavenging coefficient (SC) mean value of the BC from fossil fuel (eBC ff) for short and long rain events was 5.1 10−5 and 1.3 10−5 s−1, respectively. For the BC from biomass burning (eBC bb), the SC values were 1.6 10−4 and 2.8 10−5 s−1 in short and long events, respectively. There was a significant positive correlation between the SC and the number of drops with diameters between 0.375 and 2.5 mm. Rain scavenging of eBC was analyzed depending on the air mass origin obtaining an effective scavenging for air masses from Atlantic, Arctic and Africa. A linear model (R2 = 0.72) was built to estimate the ΔeBC values with variables from an aethalometer, a disdrometer and a weather station: eBC concentration before rain, swept volume and precipitation accumulated. A Kolmogorov-Smirnov statistical test confirmed the goodness of fit of the model to the measured data. Graphical abstract Image 1 Highlights • Hourly measures were taken of black carbon and rain during 15 months in León, Spain. • 70% of the rain events showed an effective scavenging (37% eBC decrease). • The scavenging coefficient for short rain events is 3 times the one for long events. • The scavenging was different according to specific BC source. • A model for rain scavenging of BC with aethalometer and disdrometer data was built. The combination of aethalometer and disdrometer measurements reveals that the scavenging of BC depends strongly on the BC source (biomass burning or fossil fuel combustion). [ABSTRACT FROM AUTHOR]

Summary: A new index is introduced in this article to measure the degree of normality in the speech. The proposed parameter has demonstrated to be correlated with the perceived hoarseness, giving an indication of the degree of normality. The calculation of such a parameter is based on a statistical model developed to represent normal and pathological voices. The modeling is built around Gaussian mixture models and Mel frequency cepstral coefficients. The proposed index has been named pathological likelihood index (PLI). PLI is compared with other aperiodicity features (such as jitter and shimmer), and measurements sensitive to additive noise (such as harmonics-to-noise ratio (HNR), cepstrum-based HNR, normalized noise energy, and glottal-to-noise excitation ratio). The proposed parameter is revealed to be a good estimator of the presence of pathology, showing lower correlation with noise, frequency, and amplitude perturbation parameters than these classical features among them. [ABSTRACT FROM AUTHOR]

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This paper studies the below-cloud scavenging caused by precipitation on ultrafine and accumulation modes, as well as the role of the different raindrop sizes in an urban environment. The equipment used to measure aerosol particles and raindrop variables includes a scanning mobility particle sizer spectrometer-SMPS and a Laser Precipitation Monitor (LPM), respectively. An analysis of the scavenging efficiency and the scavenging coefficient (λ) by modes and rain intensities was carried out. The main results observed have been: i) the nucleation (between 14 and 30 nm), Aitken (between 30 and 100 nm), accumulation 1 (between 100 and 300) and accumulation 2 (between 300 and 1000 nm) modes presented a scavenging efficiency of 15, 4, 22 and 21%, respectively; ii) events with rain intensities between 1 and 3 mm h−1 caused less scavenging in all modes; iii) raindrop sizes between 1.25 and 3.5 mm scavenged mainly particle sizes between 70 and 250 nm. Lower scavenging was observed on particle sizes >300 nm, and particle sizes >600 nm were only scavenged by raindrop sizes >4.75 mm; iv) the respirable fraction before and after the rain events presented a statically significant decrease of −35%. The combination in this study of SMPS and disdrometer measurements has resulted in a more detailed characterization of the influence of this process on the submicrometer aerosol fraction, noting that below-cloud scavenging is one of the main removal pathways for submicrometer aerosol particles. This study thus contributes to improving the current state of knowledge of below-cloud scavenging. [Display omitted] • The role of the different raindrop sizes in the aerosol scavenging was analyzed. • Aitken mode presented the least washing with a scavenging efficiency of 4%. • The scavenging depends on the rain intensity, mainly in accumulation mode. • Raindrops between 1.25 and 3.5 mm washed mainly the particles sizes between 70 and 300 nm. • Mass respirable fraction showed a clear decrease regardless of rain intensity. Rain intensity and raindrop size control the scavenging of ultrafine and accumulation aerosols, with raindrops of 1.25–3.5 mm being the main captors of particles between 70 and 300 nm. [ABSTRACT FROM AUTHOR]

Abstract In order to describe the means, variability and trends of the aerosol radiative effects on the southwest Atlantic coast of Europe, 11 years of aerosol light scattering (σ sp) and 4 years of aerosol light absorption (σ ap) are analyzed. A 2006–2016 trend analysis of σ sp for D < 10 μm indicates statistically significant trends for March, May–June and September–November, with a decreasing trend ranging from −1.5 to −2.8 Mm−1/year. In the 2009–2016 period, the decreasing trend is only observed for the months of June and September. For scattering Ångström exponent (SAE) there is an increasing trend during June with a rate of 0.059/year and a decreasing trend during October with −0.060/year. The trends observed may be caused by a reduction of Saharan dust aerosol or a drop in particle loading in anthropogenic influenced air masses. The relationship between SAE and absorption Ångström exponent is used to assess the aerosol typing. Based on this typing, the sub-micron particles are dominated by black carbon, mixed black and brown carbon or marine with anthropogenic influences, while the super-micrometer particles are desert dust and sea spray aerosol. The mean and standard deviation of the dry aerosol direct radiative effect at the top of the atmosphere (DRE TOA) are −4.7 ± 4.2 W m−2. DRE TOA for marine aerosol shows all observations more negative than −4 W m−2 and for anthropogenic aerosol type, DRE TOA ranges from −5.0 to −13.0 W m−2. DRE TOA of regional marine aerosol ranges from −3 to −7 W m−2, as it consists of a mixture of sea salt and anthropogenic aerosol. The variability in DRE TOA is mainly dependent on AOD, given that variations in backscatter fraction and the single scattering albedo tend to counteract each other in the radiative forcing efficiency equation. The results shown here may help in interpretation of satellite retrieval products and provide context for model evaluation. Highlights • Trend analyses detect aerosol changes from 2006 to 2016 in southwestern Europe. • It is proposed that the trends may be related to specific climatic changes. • There is a cooling aerosol direct radiative effect (DRE TOA is −4.7 ± 4.2 W m−2). • DRE TOA depends mainly on AOD as b and SSA counteract each other in forcing equation. [ABSTRACT FROM AUTHOR]

Worldwide coal is still used for household heating purposes not only because it is available and cheap but also due to behavioural issues. Regional variability in fuels and combustion appliances make accurate emission estimates from this source hard to achieve. In the present study, gaseous (CO, VOCs, SO 2 and NO X) and particulate matter (TSP) emission factors (EFs) were determined for Spanish household coal combustion covering three commercial coals and distinct combustion stages and mimicking usage patterns in real households. TSP samples were analysed to determine water-soluble inorganic ions, metal(loid)s, and organic and elemental carbon (OC and EC). Additionally, the morphology of the emitted particles was also characterised. CO (3.43–169 g kg−1), NO X (1.29–6.00 g kg−1) and SO 2 (8.96–22.3 g kg−1) EFs showed no trend regarding the combustion stage or coal type tested. On the other hand, VOC, TSP and EC EFs were higher for the ignition/devolatilisation combustion stage, regardless of the fuel tested. TSP EFs (0.085–1.08 g kg−1) increased with increasing coal volatile matter while the opposite trend was recorded for VOC emissions (0.045–3.39 gC kg−1). TSP carbonaceous matter was dominated by EC while OC represented a small fraction of the particulate mass emitted (less than 8 %wt.). Inorganic compounds composed an important fraction of the TSP samples. Sulphate particulate mass fractions (8.66–22.9 %wt.) appeared to increase with coal S-content. Coal combustion released particles with diverse morphologies, including silicate-rich particles, ferro- and glassy-spheres. This study provides novel emission factors to update emission inventories of residential coal combustion. Additionally, detailed chemical profiles were obtained for source apportionment. [Display omitted] • Gaseous and particulate emissions from the combustion of 3 types of coal were studied • Different gaseous and PM emissions were recorded over distinct combustion stages • TSP emissions appeared to be related to the coal volatile matter content • Sulphate was the major water-soluble inorganic ion for all the coal types studied • Coal combustion released silicate-rich particles, ferro- and glassy-spheres [ABSTRACT FROM AUTHOR]

Measurements of ambient aerosol particles at the University of León, León, Spain, were made in May and June 2015 with a Wideband Integrated Bioaerosol Spectrometer (WIBS). The WIBS detects Fluorescing Aerosol Particles (FAP) in the size range from 0.5 to 20 μm. These measurements were complemented with an analysis of pollen concentrations assessed with optical microscopy of samples captured with a volumetric Hirst spore trap. The total particle, FAP and pollen concentrations show clear, daily cycles. Whereas the total particle concentrations maximize at 0800 and 2200 UTC, the FAP concentrations have peaks at midnight and 0800 UTC while the pollen has a broad peak between 1200 and 2000 UTC. The FAP larger than 2 μm represent 15–35% of the total particle population in this size range, maximizing at midnight UTC. Similar to what has been found by investigators at other locations, there is a strong positive correlation of the WIBS measured FAP with relative humidity; however, the pollen concentration is positively correlated with the temperature and anti-correlated with the relative humidity. Back trajectory analysis indicates that the largest FAP to total particle fractions are found in air masses arriving from the northeast with the second largest coming from the southwest. Given the location of the university in relation to the city and forested areas, this implies that the higher concentration FAP are coming from rural, probably natural, sources; however, more local, anthropogenic sources cannot be ruled out as a secondary source. The majority of the FAP that are identified from microscopy are fungal spores ( Cladosporium , Aspergillus , Alternaria , Oidium ) and pollen grains (mainly Poaceae , Quercus , Plantago , Rumex and Urticaceae ). A comparison of the fluorescence fingerprints between laboratory generated FAP and the ambient particles showed some similarities; however, a significant fraction of the FAP are those whose fluorescence patterns do not match any of those that have been previously classified in the laboratory. [ABSTRACT FROM AUTHOR]

Logs of three common Southern and mid-European woods ( Quercus pyrenaica , Populus nigra and Fagus sylvatica ) were burned in two different combustion appliances, a fireplace and a stove. The flue gas composition was monitored continuously in the exhaust ducts of both burning appliances for total hydrocarbons (THC) and carbon oxides (CO 2 and CO). Particulate matter with aerodynamic diameter below 2.5 μm (PM 2.5 ) was sampled in a dilution tunnel under isokinetic conditions and chemically characterised for water soluble-inorganic ions, organic and elemental carbon and levoglucosan, mannosan, and galactosan. The evolution of the emission factors of these components throughout the combustion cycle was studied. The fireplace was the combustion appliance with the highest CO, CO 2 , THC and PM 2.5 emission factors. The carbonaceous matter represented 72–84% of the particulate mass emitted, regardless of species burned and combustion devices. OC/EC ratios were higher for the fireplace than for the stove, and showed a significant potential relation with K + /levoglucosan. The dominant water soluble inorganic ions in smoke particles were K + , PO 4 3 − , SO 4 2 − , and Na + . Anhydrosugar emissions were strongly enhanced in the start-up phase, when lower temperatures are registered, and decreased progressively until the glowing combustion phase. However, K + emission seems to be higher in flaming-dominated combustion at higher temperature. Statistical analyses, including the Kruskal–Wallis test, principal component analysis and Pearson correlation between emission factors, were carried out. A significant correlation between NH 4 + and levoglucosan was found for both appliances. [ABSTRACT FROM AUTHOR]

In the present study, particulate emissions from the co-combustion of forest biomass residues with sewage sludge in a pilot-scale bubbling fluidised bed combustor were characterised. The combustion flue gas was exhausted to the atmosphere after passing through a cyclone separator. Physical–chemical characteristics of the particles were studied: i) morphology and aerosol size, surface and volume distributions before the cyclone and ii) chemical composition (carbonates, water soluble-inorganic ions, organic and elemental carbon) before and after the cyclone. Chemical composition data were used to calculate aerosol density and refractive index. Aerosols showed a unimodal size distribution with a geometric mean diameter of 2.25±0.02μm and a geometric standard deviation of 1.27±0.01. The surface and volume mean diameters were 2.64±0.02μm and 2.91±0.05μm, respectively. Water-soluble inorganic ions were predominant in the fine particle fraction (PM2.5). The filters were loaded of crystallised mineral particles. The analysis revealed a dominance of calcium carbonate/oxide and halide (NaCl or KCl), sulphate and aluminosilicate nanocrystals forming larger mixed aggregates. [ABSTRACT FROM AUTHOR]

Potential step voltammetry is used to characterize the resistive and capacitive properties of electrochemical systems. Within those systems, electrochemical processes are modeled by means of equivalent circuits (ECs). In this study, we established and experimentally validated algebraic expressions describing the electrical response of those ECs. We then analyzed the features that allow significant differentiation between the ECs. Finally, we have proposed a method to graphically visualize and analyze the electrical response of the circuit to a potential step sequence. The application of this method to real electrochemical systems will allow us to not only identify the electrochemical processes taking place in an experiment but to also assess parameters such as the double layer capacitance, the solution resistance, and the polarization resistance of the redox process. [ABSTRACT FROM AUTHOR]