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481 result(s) for "Valenzuela, Antonio"
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Particle Shape Impact on the Radiative Forcing Efficiency Estimated from Single Levitated (NH4)2SO4 Particles
Levitation of single trapped particles enables the exploration of fundamental physicochemical aerosol properties never previously achieved. Experimental measurements showed that (NH4)2SO4’s particle shape deviated from sphericity during the crystallization process. Despite that, salt aerosols are assumed to be spheres even in low relative humidity (RH) in most climate models. In the analysis performed here, Mie and T-Matrix codes were operated to simulate crucial parameters needed to estimate the radiative forcing efficiency: extinction efficiency, asymmetry parameter and backscattering fraction. The incorporation of non-spherical effects in (NH4)2SO4 particles can cause a difference of up to 46% radiative forcing efficiency compared to the assumption of sphericity in the 0.3–0.6 µm particle radius range.
In-depth resistome analysis by targeted metagenomics
Background Antimicrobial resistance is a major global health challenge. Metagenomics allows analyzing the presence and dynamics of “resistomes” (the ensemble of genes encoding antimicrobial resistance in a given microbiome) in disparate microbial ecosystems. However, the low sensitivity and specificity of available metagenomic methods preclude the detection of minority populations (often present below their detection threshold) and/or the identification of allelic variants that differ in the resulting phenotype. Here, we describe a novel strategy that combines targeted metagenomics using last generation in-solution capture platforms, with novel bioinformatics tools to establish a standardized framework that allows both quantitative and qualitative analyses of resistomes. Methods We developed ResCap, a targeted sequence capture platform based on SeqCapEZ (NimbleGene) technology, which includes probes for 8667 canonical resistance genes (7963 antibiotic resistance genes and 704 genes conferring resistance to metals or biocides), and 2517 relaxase genes (plasmid markers) and 78,600 genes homologous to the previous identified targets (47,806 for antibiotics and 30,794 for biocides or metals). Its performance was compared with metagenomic shotgun sequencing (MSS) for 17 fecal samples (9 humans, 8 swine). ResCap significantly improves MSS to detect “gene abundance” (from 2.0 to 83.2%) and “gene diversity” (26 versus 14.9 genes unequivocally detected per sample per million of reads; the number of reads unequivocally mapped increasing up to 300-fold by using ResCap), which were calculated using novel bioinformatic tools. ResCap also facilitated the analysis of novel genes potentially involved in the resistance to antibiotics, metals, biocides, or any combination thereof. Conclusions ResCap, the first targeted sequence capture, specifically developed to analyze resistomes, greatly enhances the sensitivity and specificity of available metagenomic methods and offers the possibility to analyze genes related to the selection and transfer of antimicrobial resistance (biocides, heavy metals, plasmids). The model opens the possibility to study other complex microbial systems in which minority populations play a relevant role.
Synergistic Activity of Thymol with Commercial Antibiotics against Critical and High WHO Priority Pathogenic Bacteria
The use of synergistic combinations between natural compounds and commercial antibiotics may be a good strategy to fight against microbial resistance, with fewer side effects on human, animal and environmental, health. The antimicrobial capacity of four compounds of plant origin (thymol and gallic, salicylic and gentisic acids) was analysed against 14 pathogenic bacteria. Thymol showed the best antimicrobial activity, with MICs ranging from 125 µg/mL (for Acinetobacter baumannii, Pasteurella aerogenes, and Salmonella typhimurium) to 250 µg/mL (for Bacillus subtilis, Klebsiella aerogenes, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus, and Streptococcus agalactiae). Combinations of thymol with eight widely used antibiotics were studied to identify combinations with synergistic effects. Thymol showed synergistic activity with chloramphenicol against A. baumannii (critical priority by the WHO), with streptomycin and gentamicin against Staphylococcus aureus (high priority by the WHO), and with streptomycin against Streptococcus agalactiae, decreasing the MICs of these antibiotics by 75% to 87.5%. The kinetics of these synergies indicated that thymol alone at the synergy concentration had almost no effect on the maximum achievable population density and very little effect on the growth rate. However, in combination with antibiotics at the same concentration, it completely inhibited growth, confirming its role in facilitating the action of the antibiotic. The time–kill curves indicated that all the combinations with synergistic effects were mainly bactericidal.
Bcl-3 expression in the imiquimod-induced psoriasis mouse skin
Objective Psoriasis is an inflammatory process in the skin involving the loss of normal function of immune cells and keratinocytes. TNF-α is a pro-inflammatory cytokine involved in psoriasis induced by NF-κB activation. In contrast, the anti-inflammatory cytokine IL-10 can suppress macrophage TNF-α production. The non-classical NF-κB regulator, Bcl-3, can regulate IL-10 expression. Limited knowledge exists on Bcl-3 and IL-10 expression in psoriasis and their action on TNF-α. This study evaluated Bcl-3, TNF-α, and IL-10 expression levels in mouse skin in a model of imiquimod-induced psoriasis. Results Female Balb/c mice were shaved in the lumbar region and administered 62 mg of 5% imiquimod (IMQ) cream for six consecutive days. The non-lesional group received only 62 mg of cream without IMQ for six consecutive days. RT-qPCR was used to determine Bcl-3, TNF-α, and IL-10 expression. Imiquimod psoriasis induction was confirmed phenotypically and histologically. On day 2 of imiquimod treatment, the lesioned skin significantly reduced the expression level of Bcl-3, and TNF-α. However, on day 6, a significant difference in the expression of Bcl-3 (sixfold), TNF-α (twofold), and IL-10 (threefold) was found in lesioned skin compared to non-lesioned skin. Results suggest that late-stage overexpression of Bcl-3 in lesioned skin induces IL-10 expression to regulate TNF-α inflammatory effects.
Four Years of Atmospheric Boundary Layer Height Retrievals Using COSMIC-2 Satellite Data
This work aimed to study the atmospheric boundary layer height (ABLH) from COSMIC-2 refractivity data, endeavoring to refine existing ABLH detection algorithms and scrutinize the resulting spatial and seasonal distributions. Through validation analyses involving different ground-based methodologies (involving data from lidar, ceilometer, microwave radiometers, and radiosondes), the optimal ABLH determination relied on identifying the lowest refractivity gradient negative peak with a magnitude at least τ% times the minimum refractivity gradient magnitude, where τ is a fitting parameter representing the minimum peak strength relative to the absolute minimum refractivity gradient. Different τ values were derived accounting for the moment of the day (daytime, nighttime, or sunrise/sunset) and the underlying surface (land or sea). Results show discernible relations between ABLH and various features, notably, the land cover and latitude. On average, ABLH is higher over oceans (≈1.5 km), but extreme values (maximums > 2.5 km, and minimums < 1 km) are reached over intertropical lands. Variability is generally subtle over oceans, whereas seasonality and daily evolution are pronounced over continents, with higher ABLHs during daytime and local wintertime (summertime) in intertropical (middle) latitudes.
Hydroquinone Ecotoxicity: Unveiling Risks in Soil and River Ecosystems with Insights into Microbial Resilience
Despite widespread industrial use, the environmental safety of hydroquinone (HQ), a benzene compound from plants used in processes like cosmetics, remains uncertain. This study evaluated the ecotoxicological impact of HQ on soil and river environments, utilizing non-target indicator organisms from diverse trophic levels: Daphnia magna, Aliivibrio fischeri, Allium cepa, and Eisenia fetida. For a more environmentally realistic assessment, microbial communities from a river and untreated soil underwent 16S rRNA gene sequencing, with growth and changes in community-level physiological profiling assessed using Biolog EcoPlate™ assays. The water indicator D. magna exhibited the highest sensitivity to HQ (EC50 = 0.142 µg/mL), followed by A. fischeri (EC50 = 1.446 µg/mL), and A. cepa (LC50 = 7.631 µg/mL), while E. fetida showed the highest resistance (EC50 = 234 mg/Kg). Remarkably, microbial communities mitigated HQ impact in both aquatic and terrestrial environments. River microorganisms displayed minimal inhibition, except for a significant reduction in polymer metabolism at the highest concentration (100 µg/mL). Soil communities demonstrated resilience up to 100 µg/mL, beyond which there was a significant decrease in population growth and the capacity to metabolize carbohydrates and polymers. Despite microbial mitigation, HQ remains highly toxic to various trophic levels, emphasizing the necessity for environmental regulations.
Study of mineral dust entrainment in the planetary boundary layer by lidar depolarisation technique
Measurements on 27 June 2011 were performed over the Southern Iberian Peninsula at Granada EARLINET station, using active and passive remote sensing and airborne and surface in-situ data in order to study the entrainment processes between aerosols in the free troposphere and those in the planetary boundary layer (PBL). To this aim the temporal evolution of the lidar depolarisation, backscatter-related Angström exponent and potential temperature profiles were used in combination with the PBL contribution to the aerosol optical depth (AOD). Our results show that the mineral dust entrainment in the PBL was caused by the convective processes which 'trapped' the lofted mineral dust layer, distributing the mineral dust particles within the PBL. The temporal evolution of ground-based in-situ data evidenced the impact of this process at surface level. Finally, the amount of mineral dust in the atmospheric column available to be dispersed into the PBL was estimated by means of POLIPHON (Polarizing Lidar Photometer Networking). The dust mass concentration derived from POLIPHON was compared with the coarse-mode mass concentration retrieved with airborne in-situ measurements. Comparison shows differences below 50 µg/m 3 (30% relative difference) indicating a relative good agreement between both techniques.
Biocide and Copper Tolerance in Enterococci from Different Sources
Antimicrobial resistance in enterococci is a matter of concern. A collection of 272 strains (including 107 Enterococcus faecalis and 165 Enterococcus faecium strains) isolated from meat and dairy products, seafood, vegetable foods, wildflowers, animal feces (ewe, goat, horse, mule), and hospitals were tested for sensitivity to biocides of different classes (quaternary ammonium compounds, a bisphenol, and a biguanide) and copper sulfate. Most isolates were inhibited at 25 mg of benzalkonium chloride or cetrimide per liter or at 2.5 mg of hexadecylpyridinium chloride per liter. Few isolates had MICs higher than 25 mg/liter for benzalkonium chloride (2.2%), cetrimide (0.74%), or hexadecylpyridinium chloride (0.37%), although they were all inhibited at 250 mg/liter. The population response to triclosan was very homogeneous, and most isolates (98.16%) were inhibited at 250 mg of triclosan per liter. Chlorhexidine showed the greatest variability, with MICs in a range from 2.5 to 2,500 mg/liter. Remarkably, 74.57% of isolates from clinical samples required 2,500 mg of chlorhexidine per liter for inhibition, compared to much-lower concentrations required for most isolates from other sources. Enterococci were inhibited by copper sulfate in a concentration range from 4 to 16 mM, with no bimodal distribution. However, most isolates required 12 mM (41.91%) or 16 mM (47.43%) for inhibition. The highest percentages of isolates requiring 16 mM CuSO4 were from vegetable foods, seafood, and wildflowers. The results from the present study suggest intermediate levels of copper tolerance and a low incidence of biocide tolerance in the enterococci investigated, except for chlorhexidine in clinical isolates.
A comparative study of aerosol microphysical properties retrieved from ground-based remote sensing and aircraft in situ measurements during a Saharan dust event
In this work we present an analysis of aerosol microphysical properties during a mineral dust event taking advantage of the combination of different state-of-the-art retrieval techniques applied to active and passive remote sensing measurements and the evaluation of some of those techniques using independent data acquired from in situ aircraft measurements. Data were collected in a field campaign performed during a mineral dust outbreak at the Granada, Spain, experimental site (37.16° N, 3.61° W, 680 m a.s.l.) on 27 June 2011. Column-integrated properties are provided by sun- and star-photometry, which allows for a continuous evaluation of the mineral dust optical properties during both day and nighttime. Both the linear estimation and AERONET (Aerosol Robotic Network) inversion algorithms are applied for the retrieval of the column-integrated microphysical particle properties. In addition, vertically resolved microphysical properties are obtained from a multi-wavelength Raman lidar system included in EARLINET (European Aerosol Research Lidar Network), by using both LIRIC (Lidar Radiometer Inversion Code) algorithm during daytime and an algorithm applied to the Raman measurements based on the regularization technique during nighttime. LIRIC retrievals reveal the presence of dust layers between 3 and 5 km a.s.l. with volume concentrations of the coarse spheroid mode up to 60 µm3 cm−3. The combined use of the regularization and LIRIC methods reveals the night-to-day evolution of the vertical structure of the mineral dust microphysical properties and offers complementary information to that from column-integrated variables retrieved from passive remote sensing. Additionally, lidar depolarization profiles and LIRIC retrieved volume concentration are compared with aircraft in situ measurements. This study presents for the first time a comparison of the total volume concentration retrieved with LIRIC with independent in situ measurements, obtaining agreement within the estimated uncertainties for both methods and quite good agreement for the vertical distribution of the aerosol layers. Regarding the depolarization, the first published data set of the CAS-POL for polarization ratios is presented here and qualitatively compared with the lidar technique.
Evaluation of LIRIC Algorithm Performance Using Independent Sun-Sky Photometer Data at Two Altitude Levels
This work evaluates the Lidar-Radiometer Inversion Code (LIRIC) using sun-sky photometers located at different altitudes in the same atmospheric column. Measurements were acquired during an intensive observational period in summer 2012 at Aerosols, Clouds, and Trace gases Research InfraStructure Network (ACTRIS)/Aerosol Robotic Network (AERONET) Granada (GRA; 37.16°N, 3.61°W, 680 m above sea level (a.s.l.)) and Cerro Poyos (CP; 37.11°N, 3.49°W, 1820 m a.s.l.) sites. Both stations operated AERONET sun-photometry, with an additional lidar system operating at Granada station. The extended database of simultaneous lidar and sun-photometry measurements from this study allowed the statistical analysis of vertically resolved microphysical properties retrieved with LIRIC, with 70% of the analyzed cases corresponding to mineral dust. Consequently, volume concentration values were 46 μm3/cm3 on average, with a value of ~30 μm3/cm3 corresponding to the coarse spheroid mode and concentrations below 10 μm3/cm3 for the fine and coarse spherical modes. According to the microphysical properties’ profiles, aerosol particles reached altitudes up to 6000 m a.s.l., as observed in previous studies over the same region. Results obtained from comparing the LIRIC retrievals from GRA and from CP revealed good agreement between both stations with differences within the expected uncertainties associated with LIRIC (15%). However, larger discrepancies were found for 10% of the cases, mostly due to the incomplete overlap of the lidar signal and/or to the influence of different aerosol layers advected from the local origin located between both stations, which is particularly important in cases of low aerosol loads. Nevertheless, the results presented here demonstrate the robustness and self-consistency of LIRIC and consequently its applicability to large databases such as those derived from ACTRIS-European Aerosol Research Lidar Network (EARLINET) observations.