Particle hygroscopicity plays a key role in determining the particle deposition in the human respiratory tract (HRT). In this study, the effects of hygroscopicity and mixing state on regional and ...total deposition doses on the basis of the particle number concentration for children, adults, and the elderly were quantified using the Multiple-Path Particle Dosimetry
model, based on the size-resolved particle hygroscopicity measurements at
HRT-like conditions (relative humidity = 98 %) performed in the North China Plain. The measured particle population with an external mixing state was dominated by hygroscopic particles (number fraction = (91.5 ± 5.7) %, mean ± standard deviation (SD); the same below). Particle hygroscopic growth in the HRT led to a reduction by around 24 % in the total doses of submicron particles for all age groups. Such a reduction was mainly caused by the growth of hygroscopic particles and was more pronounced in the pulmonary and tracheobronchial regions. Regardless of hygroscopicity, the elderly group of people had the highest total dose among three age groups, while
children received the maximum total deposition rate. With 270 nm in
diameter as the boundary, the total deposition doses of particles smaller
than this diameter were overestimated, and those of larger particles were
underestimated, assuming no particle hygroscopic growth in the HRT. From the perspective of the daily variation, the deposition rates of hygroscopic
particles with an average of (2.88 ± 0.81) × 109 particles h−1 during the daytime were larger than those at night ((2.32 ± 0.24) × 109 particles h−1). On the contrary, hydrophobic particles interpreted as freshly emitted soot and primary organic aerosols exhibited higher deposition rates at nighttime ((3.39 ± 1.34) × 108 particles h−1) than those in the day ((2.58 ± 0.76) × 108 particles h−1). The traffic emissions during the rush hours enhanced the deposition rate of hydrophobic particles. This work provides a more explicit assessment of the impact of hygroscopicity and mixing state on the deposition pattern of submicron particles in the HRT.
Here we report results of a detailed analysis of the urban and non-urban
contributions to particulate matter (PM) concentrations and source contributions in five European
cities, namely Schiedam (the ...Netherlands, NL), Lens (France, FR), Leipzig
(Germany, DE), Zurich (Switzerland, CH) and Barcelona (Spain, ES). PM
chemically speciated data from 12 European paired monitoring sites (one
traffic, five urban, five regional and one continental background) were analysed by
positive matrix factorisation (PMF) and Lenschow's approach to assign
measured PM and source contributions to the different spatial levels. Five
common sources were obtained at the 12 sites: sulfate-rich (SSA) and nitrate-rich (NSA) aerosols,
road traffic (RT), mineral matter (MM), and aged sea salt (SS). These sources explained from 55 % to 88 % of PM
mass at urban low-traffic-impact sites (UB) depending on the country. Three
additional common sources were identified at a subset of sites/countries,
namely biomass burning (BB) (FR, CH and DE), explaining an additional 9 %–13 % of PM
mass, and residual oil combustion (V–Ni) and primary industrial (IND) (NL and ES), together explaining an additional
11 %–15 % of PM mass. In all countries, the majority of PM measured at UB
sites was of a regional+continental (R+C) nature (64 %–74 %). The R+C PM
increments due to anthropogenic emissions in DE, NL, CH, ES and FR
represented around 66 %, 62 %, 52 %, 32 % and 23 %, respectively,
of UB PM mass. Overall, the R+C PM increments due to natural and
anthropogenic sources showed opposite seasonal profiles with the former
increasing in summer and the latter increasing in winter, even if exceptions
were observed. In ES, the anthropogenic R+C PM increment was higher in
summer due to high contributions from regional SSA and V–Ni sources, both
being mostly related to maritime shipping emissions at the Spanish sites.
Conversely, in the other countries, higher anthropogenic R+C PM increments
in winter were mostly due to high contributions from NSA and BB regional
sources during the cold season. On annual average, the sources showing
higher R+C increments were SSA (77 %–91 % of SSA source contribution at the
urban level), NSA (51 %–94 %), MM (58 %–80 %), BB (42 %–78 %) and IND (91 %
in NL). Other sources showing high R+C increments were photochemistry and coal combustion (97 %–99 %;
identified only in DE). The highest regional SSA increment was observed in
ES, especially in summer, and was related to ship emissions, enhanced
photochemistry and peculiar meteorological patterns of the Western
Mediterranean. The highest R+C and urban NSA increments were observed in
NL and associated with high availability of precursors such as NOx and
NH3. Conversely, on average, the sources showing higher local
increments were RT (62 %–90 % at all sites) and V–Ni (65 %–80 % in ES and
NL). The relationship between SSA and V–Ni indicated that the contribution
of ship emissions to the local sulfate concentrations in NL has strongly
decreased since 2007 thanks to the shift from high-sulfur- to low-sulfur-content fuel used by ships. An improvement of air quality in the five cities
included here could be achieved by further reducing local (urban) emissions
of PM, NOx and NH3 (from both traffic and non-traffic sources) but
also SO2 and PM (from maritime ships and ports) and giving high
relevance to non-urban contributions by further reducing emissions of
SO2 (maritime shipping) and NH3 (agriculture) and those from
industry, regional BB sources and coal combustion.
Particle hygroscopic growth at 90% RH (relative humidity), cloud condensation nuclei (CCN) activity, and size-resolved chemical composition were concurrently measured in the Thüringer Wald mid-level ...mountain range in central Germany in the fall of 2010. The median hygroscopicity parameter values, κ, of 50, 75, 100, 150, 200, and 250 nm particles derived from hygroscopicity measurements are respectively 0.14, 0.14, 0.17, 0.21, 0.24, and 0.28 during the sampling period. The closure between HTDMA (Hygroscopicity Tandem Differential Mobility Analyzers)-measured (κHTDMA) and chemical composition-derived (κchem) hygroscopicity parameters was performed based on the Zdanovskii–Stokes–Robinson (ZSR) mixing rule. Using size-averaged chemical composition, the κ values are substantially overpredicted (30 and 40% for 150 and 100 nm particles). Introducing size-resolved chemical composition substantially improved closure. We found that the evaporation of NH4NO3, which may happen in a HTDMA system, could lead to a discrepancy in predicted and measured particle hygroscopic growth. The hygroscopic parameter of the organic fraction, κorg, is positively correlated with the O : C ratio (κorg = 0.19 × (O : C) − 0.03). Such correlation is helpful to define the κorg value in the closure study. κ derived from CCN measurement was around 30% (varied with particle diameters) higher than that determined from particle hygroscopic growth measurements (here, hydrophilic mode is considered only). This difference might be explained by the surface tension effects, solution non-ideality, gas-particle partitioning of semivolatile compounds, and the partial solubility of constituents or non-dissolved particle matter. Therefore, extrapolating from HTDMA data to properties at the point of activation should be done with great care. Finally, closure study between CCNc (cloud condensation nucleus counter)-measured (κCCN) and chemical composition (κCCN, chem) was performed using CCNc-derived κ values for individual components. The results show that the κCCN can be well predicted using particle size-resolved chemical composition and the ZSR mixing rule.
To fight against the first wave of coronavirus disease 2019
(COVID-19) in 2020, lockdown measures were implemented in most European
countries. These lockdowns had well-documented effects on human ...mobility. We
assessed the impact of the lockdown implementation and relaxation on air
pollution by comparing daily particulate matter (PM), nitrogen dioxide
(NO2) and ozone (O3) concentrations, as well as particle number
size distributions (PNSDs) and particle light absorption coefficient in situ
measurement data, with values that would have been expected if no COVID-19 epidemic had occurred
at 28 sites across Europe for the period 17 February–31 May 2020.
Expected PM, NO2 and O3 concentrations were calculated from the
2020 Copernicus Atmosphere Monitoring Service (CAMS) ensemble forecasts,
combined with 2019 CAMS ensemble forecasts and measurement data. On average,
lockdown implementations did not lead to a decrease in PM2.5 mass
concentrations at urban sites, while relaxations resulted in a +26 ± 21 % rebound. The impacts of lockdown implementation and relaxation on
NO2 concentrations were more consistent (−29 ± 17 and +31 ± 30 %, respectively). The implementation of the lockdown measures
also induced statistically significant increases in O3 concentrations
at half of all sites (+13 % on average). An enhanced oxidising capacity
of the atmosphere could have boosted the production of secondary aerosol at
those places. By comparison with 2017–2019 measurement data, a
significant change in the relative contributions of wood and fossil fuel
burning to the concentration of black carbon during the lockdown was
detected at 7 out of 14 sites. The contribution of particles smaller than 70 nm to the total number of particles significantly also changed at most of
the urban sites, with a mean decrease of −7 ± 5 % coinciding with
the lockdown implementation. Our study shows that the response of PM2.5
and PM10 mass concentrations to lockdown measures was not systematic at
various sites across Europe for multiple reasons, the relationship between
road traffic intensity and particulate air pollution being more complex than
expected.
Humic-like substances (HULIS) comprise a significant fraction of the organic compounds in aerosol particles. In the present study we report the chemical properties of HULIS samples originating from ...urban (Copenhagen, Denmark), rural (Melpitz, Germany) and remote (Storm Peak Laboratory, CO, USA) environments. Suwannee River Fulvic Acid Standard (SRFA) was included in the study as a reference. Raman, Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy were used together with high performance liquid chromatography-mass spectrometry (HPLC-MS) for characterisation of the samples. The same main functional groups were present in all samples, but the relative abundance of functional groups varied among the studied samples, which was mainly evident from the FTIR spectra. The urban and rural samples were found to be very similar with respect to the relative abundance of functional groups. The remote sample contained relatively more C=O and COOH groups, which may be due to the remote environment. Organonitrates appeared to be present in the three atmospheric samples, while it did not appear to be present in the SRFA. The SRFA sample comprised significantly larger amounts of aromatic groups relative to the atmospheric samples in line with previous findings. All the obtained mass spectra showed clear periods of 14-16 Da in line with previous studies. The estimated average molecular weight (AMW) was comparable for the atmospheric samples within the errors - while the AMW of SRFA was higher. In general the atmospheric HULIS samples from different environments were rather similar with respect to the properties investigated.
Fine particulate matter (PM2.5) samples collected at Mount (Mt.) Tai in the North China Plain during summer 2014 were analyzed for dicarboxylic acids and related compounds (oxocarboxylic acids and ...α-dicarbonyls) (DCRCs). The total concentration of DCRCs was 1050±580 and 1040±490 ng m-3 during the day and night, respectively. Although these concentrations were about 2 times lower than similar measurements in 2006, the concentrations reported here were about 1–13 times higher than previous measurements in other major cities in the world. Molecular distributions of DCRCs revealed that oxalic acid (C2) was the dominant species (50 %), followed by succinic acid (C4) (12 %) and malonic acid (C3) (8 %). WRF modeling revealed that Mt. Tai was mostly in the free troposphere during the campaign and long-range transport was a major factor governing the distributions of the measured compounds at Mt. Tai. A majority of the samples (79 %) had comparable concentrations during the day and night, with their day–night concentration ratios between 0.9 and 1.1. Multi-day transport was considered an important reason for the similar concentrations. Correlation analyses of DCRCs and their gas precursors and between C2 and sulfate indicated precursor emissions and aqueous-phase oxidations during long-range transport also likely play an important role, especially during the night. Source identification indicated that anthropogenic activities followed by photochemical aging accounted for about 60 % of the total variance and were the dominant source at Mt. Tai. However, biomass burning was only important during the first half of the measurement period. Measurements of potassium (K+) and DCRCs were about 2 times higher than those from the second half of the measurement period. The concentration of levoglucosan, a biomass burning tracer, decreased by about 80 % between 2006 and 2014, indicating that biomass burning may have decreased between 2006 and 2014.
Emerging data show that microRNA 193a-3p (miR-193a-3p) has a suppressive role in many cancers and is often downregulated in tumors, as compared to surrounding normal tissues. Therefore, mimics of ...miR-193a-3p could be used as an attractive therapeutic approach in oncology. To better understand and document the molecular mechanism of action of 1B3, a novel synthetic miRNA-193a-3p mimic, RNA sequencing was performed after transfection of 1B3 in six different human tumor cell lines. Genes differentially expressed (DE) in at least three cell lines were mapped by Ingenuity Pathway Analysis (IPA), and interestingly, these results strongly indicated upregulation of the tumor-suppressive phosphatase and tensin homolog (PTEN) pathway, as well as downregulation of many oncogenic growth factor signaling pathways. Importantly, although unsurprisingly, IPA identified miR-193a-3p as a strong upstream regulator of DE genes in an unbiased manner. Furthermore, biological function analysis pointed to an extensive link of 1B3 with cancer, via expected effects on tumor cell survival, proliferation, migration, and cell death. Our data strongly suggest that miR-193a-3p/1B3 is a potent tumor suppressor agent that targets various key oncogenic pathways across cancer types. Therefore, the introduction of 1B3 into tumor cells may represent a promising strategy for cancer treatment.
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1B3 is a mimic of the naturally occurring miRNA-193a-3p, a gene regulator that has potent tumor suppressor functions. We characterized the effect of 1B3 on gene expression in six human cancer cell lines. 1B3 was shown to strongly activate tumor suppressor pathways while inhibiting oncogenic cell signaling.
The aerosol size-segregated chemical composition was analyzed at an urban (Bologna) and a rural (San Pietro Capofiume) site in the Po Valley, Italy, during June and July 2012, by ion-chromatography ...(major water-soluble ions and organic acids) and evolved gas analysis (total and water-soluble carbon), to investigate sources and mechanisms of secondary aerosol formation during the summer. A significant enhancement of secondary organic and inorganic aerosol mass was observed under anticyclonic conditions with recirculation of planetary boundary layer air but with substantial differences between the urban and the rural site. The data analysis, including a principal component analysis (PCA) on the size-resolved dataset of chemical concentrations, indicated that the photochemical oxidation of inorganic and organic gaseous precursors was an important mechanism of secondary aerosol formation at both sites. In addition, at the rural site a second formation process, explaining the largest fraction (22 %) of the total variance, was active at nighttime, especially under stagnant conditions. Nocturnal chemistry in the rural Po Valley was associated with the formation of ammonium nitrate in large accumulation-mode (0.42–1.2 µm) aerosols favored by local thermodynamic conditions (higher relative humidity and lower temperature compared to the urban site). Nocturnal concentrations of fine nitrate were, in fact, on average 5 times higher at the rural site than in Bologna. The water uptake by this highly hygroscopic compound under high RH conditions provided the medium for increased nocturnal aerosol uptake of water-soluble organic gases and possibly also for aqueous chemistry, as revealed by the shifting of peak concentrations of secondary compounds (water-soluble organic carbon (WSOC) and sulfate) toward the large accumulation mode (0.42–1.2 µm). Contrarily, the diurnal production of WSOC (proxy for secondary organic aerosol) by photochemistry was similar at the two sites but mostly affected the small accumulation mode of particles (0.14–0.42 µm) in Bologna, while a shift to larger accumulation mode was observed at the rural site. A significant increment in carbonaceous aerosol concentration (for both WSOC and water-insoluble carbon) at the urban site was recorded mainly in the quasi-ultrafine fraction (size range 0.05–0.14 µm), indicating a direct influence of traffic emissions on the mass concentrations of this range of particles.
Compelling evidence demonstrates that miR-193a-3p is a tumor suppressor microRNA in many cancer types, and its reduced expression is linked to cancer initiation and progression, metastasis, and ...therapy resistance. However, its mechanism of action is not consistently described between studies, and often contradicts the pleiotropic role of a microRNA in manipulating several different mRNA targets. We therefore comprehensively investigated miRNA-193a-3p's mode of action in a panel of human cancer cell lines, with a variety of genetic backgrounds, using 1B3, a synthetic microRNA mimic. Interestingly, the exact mechanism through which 1B3 reduced cell proliferation varied between cell lines. 1B3 efficiently reduced target gene expression, leading to reduced cell proliferation/survival, cell cycle arrest, induction of apoptosis, increased cell senescence, DNA damage, and inhibition of migration. SiRNA silencing of 1B3 target mRNAs further highlighted the advantage of the pleiotropic mechanism of 1B3 action, as repression of individual targets did not achieve the same robust effect on cell proliferation in all cell lines. Importantly, a novel lipid nanoparticle-based formulation of 1B3, INT-1B3, demonstrated marked anti-tumor activity as a single agent following systemic administration in tumor-bearing mice. Together, these data strongly support the development of 1B3 as a novel therapeutic agent for treatment of human cancer.
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