Examinando por Autor "Fuentes, F."
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Ítem Biomineralization of lithium nanoparticles by Li-resistant Pseudomonas rodhesiae isolated from the Atacama salt flat(BioMed Central Ltd, 2022-03) Bruna, N.; Galliani, E.; Oyarzún, P.; Bravo, D.; Fuentes, F.; Pérez-Donoso, J.Background: The Atacama salt flat is located in northern Chile, at 2300 m above sea level, and has a high concentration of lithium, being one of the main extraction sites in the world. The effect of lithium on microorganism communities inhabiting environments with high concentrations of this metal has been scarcely studied. A few works have studied the microorganisms present in lithium-rich salt flats (Uyuni and Hombre Muerto in Bolivia and Argentina, respectively). Nanocrystals formation through biological mineralization has been described as an alternative for microorganisms living in metal-rich environments to cope with metal ions. However, bacterial lithium biomineralization of lithium nanostructures has not been published to date. In the present work, we studied lithium-rich soils of the Atacama salt flat and reported for the first time the biological synthesis of Li nanoparticles. Results: Bacterial communities were evaluated and a high abundance of Cellulomonas, Arcticibacter, Mucilaginibacter, and Pseudomonas were determined. Three lithium resistant strains corresponding to Pseudomonas rodhesiae, Planomicrobium koreense, and Pseudomonas sp. were isolated (MIC > 700 mM). High levels of S2− were detected in the headspace of P. rodhesiae and Pseudomonas sp. cultures exposed to cysteine. Accordingly, biomineralization of lithium sulfide-containing nanomaterials was determined in P. rodhesiae exposed to lithium salts and cysteine. Transmission electron microscopy (TEM) analysis of ultrathin sections of P. rodhesiae cells biomineralizing lithium revealed the presence of nanometric materials. Lithium sulfide-containing nanomaterials were purified, and their size and shape determined by dynamic light scattering and TEM. Spherical nanoparticles with an average size < 40 nm and a hydrodynamic size ~ 44.62 nm were determined. Conclusions: We characterized the bacterial communities inhabiting Li-rich extreme environments and reported for the first time the biomineralization of Li-containing nanomaterials by Li-resistant bacteria. The biosynthesis method described in this report could be used to recover lithium from waste batteries and thus provide a solution to the accumulation of batteries.Ítem Forearc tectonics and volcanism during the Devonian–Carboniferous evolution of the North Patagonian segment, southern Chile (41,3°S)(Frontiers Media S.A., 2022-09) Palape, C.; Quezada, P.; Bastías, J.; Hervé, F.; Reyes, T.; Veas, M.; Vildoso, F.; Calderón, M.; Theye, T.; Fuentes, F.; Chiaradia, M.Late Paleozoic to early Mesozoic subduction complexes formed during the evolution of southwestern Gondwana and extensively crop out along the Chilean continental margin. Recent findings in northern Patagonia (40°–43°S) revealed that accretionary processes were active since the Devonian when enhanced lithosphere stretching in the forearc led to the formation of Chaitenia island arc. The extension in the crust consecutively developed a backarc basin, which culminated during a compressive episode that re-amalgamated the Chaitenia island arc with the margin. This episode produced intermediate grade metamorphism in the sedimentary rocks that were formed throughout the extension. To constrain the tectonic evolution of these processes, we combined petrology, structural analysis, whole-rock geochemical, and whole-rock isotopic tracing (Sr-Nd-Pb) data along with thermodynamic modelling. Two petro-tectonic domains are here defined. The Western Coastal Range Domain is composed of Carboniferous to Permian metapsammopelitic rocks, which are mainly schists with a metasedimentary Carboniferous protolith exhibiting a penetrative northeast to southwest dipping main foliation associated with basal accretion. The Eastern Coastal Range Domain is comprised by garnet micaschists, metabasalts, metarhyolites, and metasandstones. This unit is folded by three ductile structures: The first is related to rootless isoclinal folds, the second is associated with kilometric scale west-verging tight folds, and the third is associated with west-verging cylindrical folds. The volcanic rocks of this domain are comprised by middle Devonian alkaline metarhyolites and metabasalts with enriched-MORB and normal-MORB affinities. Trace element composition suggests that the metabasalts formed through shallow melting in an extensional setting over a supra-subduction zone. Nd and Pb isotope data point to a mantle source change for the basaltic melts from an EM1-like to a DM-like and are interpreted to reflect the embryonic to mature evolution of the early Devonian to Carboniferous backarc system. The calculated P–T evolution of the garnet micaschists follows: 1) a clockwise IP–IT prograde Barrovian path, 2) an isobaric thermal increase at ∼7 kbar and 540°C, and 3) an adiabatic decompression. Finally, after the metamorphism, these rocks were uplifted by thrusting processes that probably occurred during the late Permian. Copyright © 2022 Palape, Quezada, Bastías, Hervé, Reyes, Veas, Vildoso, Calderón, Theye, Fuentes and Chiaradia.Ítem Impact of 1% malic acid spray on the oral health-related quality of life of patients with xerostomia(Nihon University, School of Dentistry, 2018-06) Niklander, S.; Fuentes, F.; Sanchez, D.; Araya, V.; Chiappini, G.; Martinez, R.; Marshall, M.Dry mouth sensation, also known as xerostomia, is a common clinical problem with an increasing prevalence. Although recent studies have reported promissory results of malic acid, none have evaluated the impact of malic acid on the oral health-related quality of life (OHRQoL) of patients with xerostomia. Thus, this study aimed to evaluate the impact of 1% malic acid, combined with fluoride and xylitol, on the OHRQoL of patients with xerostomia. We enrolled 70 patients and randomly allocated them into two groups: the intervention group (applied topical sialogogue with 1% malic acid) and the control group (applied a placebo). We assessed the OHRQoL and severity of xerostomia before and after treatment with the Spanish version of the Oral Health Impact Profile-14 questionnaire (OHIP-14sp) and a visual analogue scale (VAS), respectively. In addition, stimulated and non-stimulated salivary flow rates before and after treatments were also measured. In total, 60 patients completed the study. According to the VAS, both sprays significantly improved dry mouth sensation (P < 0.001). However, OHIP-14sp total scores decreased significantly in the intervention group from 20.8 ± 10.4 to 16.5 ± 9.5 (P < 0.001), indicating an improvement in the OHRQoL. No significant differ- ences were observed in the control group (P > 0.05). Furthermore, non-stimulated salivary flow rates significantly increased in the intervention group from 0.25 ± 0.22 to 0.33 ± 0.33 mL/min (P < 0.001). Overall, this study demonstrated that malic acid improves the OHRQoL and dry mouth sensation in patients with xerostomia. © 2018, Nihon University, School of Dentistry. All rights reserved.Ítem Risk factors, hyposalivation and impact of xerostomia on oral health-related quality of life(Sociedade Brasileira de Pesquisa Odontológica - SBPqO, 2017-01) Niklander, S.; Veas, L.; Barrera, C.; Fuentes, F.; Chiappini, G.; Marshall, M.To determine xerostomia-related frequency, factors, salivary flow rates and Oral Health-Related Quality of Life (OHRQoL) of patients attending the Universidad Andrés Bello Dental School Clinic, in the city of Viña del Mar, Chile. The study involved 566 patients assessed with xerostomia, based on a single standardized questionnaire. The severity and impact of xerostomia on OHRQoL was assessed using a visual analogue scale (VAS) and the short version of the Oral Health Impact Profile Questionnaire (OHIP-14sp), respectively. Stimulated and non-stimulated salivary flow rates were obtained from a sample of patients. Xerostomia was reported in 61 patients (10.8%), comprising 50 women (83.3%) and 11 men (16.7%) (p < 0.013). The prevalence was 13% among the women and 6.1% among the men. Gender, age and medication were found to be independent risk factors for the development of xerostomia. Hyposalivation was found in 10 of the 35 patients with xerostomia (28.6%) and in 2 patients without it (p < 0.011). Patients with xerostomia had a reduced OHRQoL, compared with patients without xerostomia, as shown by the total OHIP-14sp score (p < 0.001). Xerostomia was a common, potentially debilitating condition with a major impact on the OHRQoL of a patient population attending a university-based dental clinic. Hyposalivation was present in almost 30% of the patients who complained of xerostomia. It is important that general dentists be aware of this condition, so that they can provide patients with a good diagnosis, treatment and follow-up.Ítem Risk factors, hyposalivation and impact of xerostomia on oral health-related quality of life(2017) Niklander, S.; Veas, L.; Barrera, C.; Fuentes, F.; Chiappini, G.; Marshall, M.To determine xerostomia-related frequency, factors, salivary flow rates and Oral Health-Related Quality of Life (OHRQoL) of patients attending the Universidad Andrés Bello Dental School Clinic, in the city of Viña del Mar, Chile. The study involved 566 patients assessed with xerostomia, based on a single standardized questionnaire. The severity and impact of xerostomia on OHRQoL was assessed using a visual analogue scale (VAS) and the short version of the Oral Health Impact Profile Questionnaire (OHIP-14sp), respectively. Stimulated and non-stimulated salivary flow rates were obtained from a sample of patients. Xerostomia was reported in 61 patients (10.8%), comprising 50 women (83.3%) and 11 men (16.7%) (p < 0.013). The prevalence was 13% among the women and 6.1% among the men. Gender, age and medication were found to be independent risk factors for the development of xerostomia. Hyposalivation was found in 10 of the 35 patients with xerostomia (28.6%) and in 2 patients without it (p < 0.011). Patients with xerostomia had a reduced OHRQoL, compared with patients without xerostomia, as shown by the total OHIP-14sp score (p < 0.001). Xerostomia was a common, potentially debilitating condition with a major impact on the OHRQoL of a patient population attending a university-based dental clinic. Hyposalivation was present in almost 30% of the patients who complained of xerostomia. It is important that general dentists be aware of this condition, so that they can provide patients with a good diagnosis, treatment and follow-up.Ítem Ultramafic rocks in the North Patagonian Andes: is their emplacement associated with the Neogene tectonics of the Liquiñe–Ofqui Fault Zone?(Servicio Nacional de Geologia y Mineria, 2017-01) Hervé, F.; Fuentes, F.; Calderón, M.; Fanning, M.; Quezada, P.; Pankhurst, R.; Rapela, C.Serpentinites and fresh or partially serpentinized harzburgite crop out in the western slope of the North Patagonian Andes of continental Chiloé (41°44’-42°12’S). These rocks are spatially associated with low-grade metamorphic rocks containing Cenozoic detrital zircons. The metamorphic rocks, together with Devonian metasediments, have been mapped previously as Late Paleozoic-Triassic metamorfic complex, an age no longer tenable for at least part of the complex. Transpressional tectonic emplacement of the ultramafic body or bodies is thought to have been related to activity on the Liquiñe-Ofqui Fault Zone, following a late Oligocene-Early Miocene extensional phase in the forearc region of the present Andes. This fault zone occurs immediately east of the outcrops of the ultramafic rocks and has been interpreted previously as generating a hemi-flower or flower structure.