Calificación de operaciones de un espectrómetro de fluorescencia de rayos X

Este trabajo es una guía genérica para la calificación de operación de un espectrómetro de fluorescencia de rayos X SIEMENS SRS 3000 (Longitud de onda). Para este fin se presentan varias pruebas que se aplicaron a componentes principales (calificación de operación) que integran al instrumento. Esto permitirá reconocer si el instrumento se encuentra en óptimas condiciones de medición, de acuerdo a las especificaciones del proveedor, para ofrecer integridad en sus resultados analítico

Hybrid photonic-plasmonic cavities based on the nanoparticle-on-a-mirror configuration

[EN] Hybrid photonic-plasmonic cavities have emerged as a new platform to increase light-matter interaction capable to enhance the Purcell factor in a singular way not attainable with either photonic or plasmonic cavities separately. In the hybrid cavities proposed so far, the plasmonic element is usually a metallic bow-tie antenna, so the plasmonic gap-defined by lithography-is limited to minimum values of several nanometers. Nanoparticle-on-a-mirror (NPoM) cavities are far superior to achieve the smallest possible mode volumes, as plasmonic gaps smaller than 1 nm can be created. Here, we design a hybrid cavity that combines an NPoM plasmonic cavity and a dielectric-nanobeam photonic crystal cavity operating at transverse-magnetic polarization. The metallic nanoparticle can be placed very close (<1 nm) to the upper surface of the dielectric cavity, which acts as a low-reflectivity mirror. We demonstrate through numerical calculations of the local density of states that this hybrid plasmonic-photonic cavity exhibits quality factors Q above 10(3) and normalized mode volumes V down to 10(-3), thus resulting in high Purcell factors (F-P approximate to 10(5)), while being experimentally feasible with current technology. Our results suggest that hybrid cavities with sub-nanometer gaps should open new avenues for boosting light -matter interaction in nanophotonic systems.Horizon 2020 Framework Programme (829067 THOR); Generalitat Valenciana (PPC/2018/002, PROMETEO/2019/123); Ministerio de Ciencia, Innovacion y Universidades (PGC2018-094490-B, PRX18/00126); Alexander von Humboldt-Stiftung.Barreda, ÁI.; Zapata-Herrera, M.; Palstra, IM.; Mercadé-Morales, L.; Aizpurua, J.; Koenderink, AF.; Martínez Abietar, AJ. (2021). Hybrid photonic-plasmonic cavities based on the nanoparticle-on-a-mirror configuration. Photonics Research. 9(12):2398-2419. https://doi.org/10.1364/PRJ.433761S2398241991

Photo-Fenton process at natural conditions of pH, iron, ions, and humic acids for degradation of diuron and amoxicillin

Effect of ferric ions at concentrations typically found in natural waters (0.05 to 1.06 mg L−1) and low H2O2 concentrations (between 0.5 and 17.9 mg L−1) on simulated sunlight-induced (300 W m−2) photo-Fenton degradation at initial neutral pH (7.0) of amoxicillin and diuron in Milli-Q water was studied using an rotatable central composite experimental design 22 with a central and two axial points. H2O2 concentration was the parameter playing the key role on the degradation of both pollutants. Despite that initial pH was 7.0 in Milli-Q water, this latter decreased rapidly in the first minutes, reaching values of 3.5 and 5.0 for diuron and amoxicillin respectively after 15 min of simulated sunlight irradiation. In contrast, in presence of bicarbonate/carbonate (HCO3 −/CO3 =), fluoride (F−), and humic acids (HAs) at concentrations found often in surface and well waters with ferric ion and H2O2 concentrations of 0.3 and 9.7 and 15.2 mg L−1 respectively, both pollutants exhibited a strong degradation keeping the circumneutral pH. Amoxicillin and diuron degradation byproducts found by HPLC/MS were compatible with HO• and/or CO3 –• radical attack. Several photo-induced processes such as photo-Fenton (by dissolved ferric-HA complexes), heterogeneous photocatalysis (by colloidal iron), UV-B H2O2 photolysis, irradiated-dissolved organic matter, and their reactions with pollutants would be the main oxidative route responsible of degradations. These findings demonstrated that it could be possible using iron concentrations often found in natural waters to oxidize via photo-Fenton processes among other events, organic pollutants at natural pH conditions.Fil: Buitrago, Jose L.. Universidad Tecnológica de Pereira; ColombiaFil: Sanabria, Janeth. Universidad del Valle; ColombiaFil: Gútierrez Zapata, Héctor M.. Universidad del Valle; ColombiaFil: Urbano Ceron, Frankly J.. Instituto Nacional de Medicina Legal y Ciencias Forenses; ColombiaFil: García Barco, Alejandra. Universidad Tecnológica de Pereira; ColombiaFil: Osorio Vargas, Paula Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina. Universidad Tecnológica de Pereira; Colombia. Universidad del Bio Bio; ChileFil: Rengifo Herrera, Julian Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentin

Colposcopy in the Primary Health Care: A Scoping Review

Aim: Low- and middle-income countries represent nearly 85% of all cervical cancer cases worldwide; thereby, it is extremely important to identify methods to improve the screening process. Therefore, this study aimed to summarize the primary characteristics of studies on accessibility, coverage, patient preferences, and factors associated with patient satisfaction or acceptance of colposcopy in primary healthcare. Methods: A search strategy, based on MeSH, Emtree, and free terms, was run through 5 databases (PubMed, Scopus, Embase, Ovid/Medline, and Web of Science). EndNote 20.1 © and Rayyan QCRI © were used for screening. A preset datasheet was used for data extraction. Results: The systematic search retrieved 1127 references, and after removing duplicates, screening the titles and abstracts, and reviewing the full text, 7 studies were included. The interrater reliability was 77.73% (kappa statistic = 0.1842). Most studies estimated the proportion of women that sought for colposcopy after a previous screening test for human papilloma virus. One study identifies barriers to colposcopy examination in women at risk of developing cervical cancer. Three studies assessed the decentralization of colposcopy from a tertiary healthcare center to a primary care center. Pap smear was the most common first-line screening test, followed by liquid-based cytology sample and visual inspection with acetic acid. Conclusion: Only a few countries have investigated the use of colposcopy in primary care. Thus, barriers and the care structure for this implementation to be successful in reducing cervical cancer incidence and mortality should be identified.Revisión por pare

Probing the role of grain boundaries in single Cu nanoparticle oxidation by in situ plasmonic scattering

Grain boundaries determine physical properties of bulk materials including ductility, diffusivity, and electrical conductivity. However, the role of grain boundaries in nanostructures and nanoparticles is much less understood, despite the wide application of nanoparticles in nanophotonics, nanoelectronics, and heterogeneous catalysis. Here, we investigate the role of high-angle grain boundaries in the oxidation of Cu nanoparticles, using a combination of in situ single particle plasmonic nanoimaging and postmortem transmission electron microscopy image analysis, together with ab initio and classical electromagnetic calculations. We find an initial growth of a 5-nm-thick Cu2O shell on all nanoparticles, irrespective of different grain morphologies. This insensitivity of the Cu2O shell on the grain morphology is rationalized by extraction of Cu atoms from the metal lattice being the rate limiting step, as proposed by density functional theory calculations. Furthermore, we find that the change in optical scattering intensity measured from the individual particles can be deconvoluted into one contribution from the oxide layer growth and one contribution that is directly proportional to the grain boundary density. The latter contribution signals accumulation of Cu vacancies at the grain boundaries, which, as corroborated by calculations of the optical scattering, leads to increased absorption losses and thus a decrease of the scattering, thereby manifesting the role of grain boundaries as vacancy sinks and nuclei for Kirkendall void formation at a later stage of the oxidation process

Self-Medication Practices, Use of Brand-Name, and Over-the-Counter Medicines by Peruvian Older Adults

Background Older adults are a particularly vulnerable group to drug use and self-medication. The aim of the study was to evaluate self-medication as a factor associated with the purchase of brand-name and over-the-counter (OTC) drugs in older adults in Peru. Methods A secondary analysis was performed using an analytical cross-sectional design of data from a nationally representative survey from 2014 to 2016. The exposure variable was self-medication, defined as the purchase of medicines without a prescription. The dependent variables were purchases of brand-name and OTC drugs, both as a dichotomous response (yes/no). Information of sociodemographic variables, health insurance, and the types of drugs purchased by the participants was collected. Crude prevalence ratios (PR) were calculated and adjusted using generalized linear models of the Poisson family, considering the complex sample of the survey. Results In this study, 1,115 respondents were evaluated, with a mean age of 63.8 years and a male proportion of 48.2%. The prevalence of self-medication was 66.6%, while the proportions of purchases of brand-name and OTC drugs were 62.4% and 23.6%, respectively. The adjusted Poisson regression analysis revealed an association between self-medication and the purchase of brand-name drugs (adjusted PR [aPR]=1.09; 95% confidence interval [CI]: 1.01–1.19). Likewise, self-medication was associated with the purchase of OTC medications (aPR=1.97; 95%CI: 1.55–2.51). Conclusions This study evidenced a high prevalence of self-medication in Peruvian older adults. Two-thirds of the surveyed people bought brand-name drugs, whereas one-quarter bought OTC drugs. Self-medication was associated with a greater likelihood of buying brand-name and OTC drugs

The effects of thymoquinone on pancreatic cancer: Evidence from preclinical studies

Thymoquinone (TQ) is a secondary metabolite found in abundance in very few plant species including Nigella sativa L., Monarda fistulosa L., Thymus vulgaris L. and Satureja montana L. Preclinical pharmacological studies have shown that TQ has many biological activities, such as anti-inflammatory, antioxidant and anticancer. Both in vivo and in vitro experiments have shown that TQ acts as an antitumor agent by altering cell cycle progression, inhibiting cell proliferation, stimulating apoptosis, inhibiting angiogenesis, reducing metastasis and affecting autophagy. In this comprehensive study, the evidence on the pharmacological potential of TQ on pancreatic cancer is reviewed. The positive results of preclinical studies support the view that TQ can be considered as an additional therapeutic agent against pancreatic cancer. The possibilities of success for this compound in human medicine should be further explored through clinical trials. © 2022 The Author

Stomatal Density and its Relationship with Yield of Radish (Raphanus Sativus L.) Fertilized with Biol Produced from Sugar Cane Residues

The impact of agro-industrial waste can be reduced by using it in crop fertilization. The aim of this study was to evaluate the stomatal density and yield of radish (Raphanus Sativus L.) fertilized with biol at different concentrations, produced from sugar cane residues. A completely randomized blocks design statistical model was used, which consisted of 5 tests with 3 repetitions for each one, being T1 the control trial, and T2, T3, T4 and T5 the treatments using 2, 3, 4 and 5 L of biol in 200 L of water respectively. In terms of crop physical characteristics, the T5 treatment excelled in plant length, equatorial diameter, plant weight, as well as yield with 12.71 t/ha. Likewise, in the chemical analysis of the radish leaves, the T5 treatment showed an increase in K, Ca, Zn and MN, while the T2 did it in N, P and Cu, the T3 in Fe and the T4 in Mg. In terms of stomatal density, T5 stood out with 122 stomatal/mm2. Based on this, it is concluded that the increase in the dose of biol influences the increase in nutrient and stomatal density and hence the yield of the radish crop

Direction‐sensitive magnetophotonic surface crystals

Nanometer-thin rare-earth–transition-metal (RE–TM) alloys with precisely controlled compositions and out-of-plane magnetic anisotropy are currently in the focus for ultrafast magnetophotonic applications. However, achieving lateral nanoscale dimensions, crucial for potential device downscaling, while maintaining designable optomagnetic functionality and out-of-plane magnetic anisotropy is extremely challenging. Herein, nanosized Tb18Co82 ferrimagnetic alloys, having strong out-of-plane magnetic anisotropy, within a gold plasmonic nanoantenna array to design a micrometer-scale magnetophotonic crystal that exhibits abrupt and narrow magneto-optical (MO) spectral features that are both magnetic field and light incidence direction controlled are integrated. The narrow Fano-type resonance arises through the interference of the individual nanoantenna's surface plasmons and a Rayleigh anomaly of the whole nanoantenna array, in both optical and MO spectra, which are demonstrated and explained using Maxwell theory simulations. This robust magnetophotonic crystal opens the way for conceptually new high-resolution light incidence direction sensors, as well as for building blocks for plasmon-assisted all-optical magnetization switching in ferrimagnetic RE–TM alloys

Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.