Publications by authors named "Luis F Silva"

Although semiconducting metal oxide (SMOx) nanoparticles (NPs) have attracted attention as sensing materials, the methodologies available to synthesize them with desirable properties are quite limited and/or often require relatively high energy consumption. Thus, we report herein the processing of Zn-doped SnO NPs via a microwave-assisted nonaqueous route at a relatively low temperature (160 °C) and with a short treatment time (20 min). In addition, the effects of adding Zn in the structural, electronic, and gas-sensing properties of SnO NPs were investigated.

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Motivation: Severe to profound sensorineural hearing loss interferes with a child's development at the cognitive, linguistic, academic, and social levels. Since the beginning of the pediatric auditory rehabilitation program through cochlear implantation in the Ear, Nose, and Throat (ENT) Service of the Coimbra Hospital and University Center (CHUC), Portugal, its mentors defended the early diagnosis of hearing loss followed by timely intervention, and this was considered the starting point to optimize (re)habilitation through this method. Three decades or so later, recently we conducted this study to evaluate the performance of patients implanted in the initial phase of the cochlear implantation program.

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A promissory technic for reducing environmental contaminants is the production of biochar from waste reuse and its application for water treatment. This study developed biochar (CWb) and NHCl-modified biochar (MCWb) using cassava residues as precursors. CWb and MCWb were characterized and evaluated in removing dyes (Acid Blue 9 and Food Red 17) in a binary system.

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The present article analyzed the process of precarious work relations in the health sector, demonstrating how this situation generated illness and suffering among workers. The text sought to register how the institutional adoption of neoliberal economic conceptions, of the reduction of State social policies, coupled with a history of cultural rejection of labor rights, provided the attraction of mechanisms of precarious work for the public sector, notably, the outsourcing of labor and the provision of services. In a second moment, the text points out the legal improprieties committed, presenting the consequences of the weakening of the legal bond in the working conditions of these workers, mainly regarding working hours and remuneration, also highlighting how much the dissemination of these links represented a factor of a general reduction in wages and labor and social security rights in the sector.

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Article Synopsis
  • Silver tungstate (AgWO) exists in three crystalline forms: orthorhombic (α), hexagonal (β), and cubic (γ), which were successfully synthesized using a simple ambient temperature precipitation method.
  • The synthesis method relied on manipulating the volumetric ratios of silver nitrate and tungstate sodium dehydrate, while various analytical techniques were used to investigate the structural and electronic properties of the AgWO polymorphs.
  • First-principles calculations provided insights into the atomic-level characteristics, and the study linked the local coordination of elements to the photocatalytic and antibacterial properties of the polymorphs against specific compounds under UV light.
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A novel approach for the online coupling of solid-phase microextraction (SPME) and liquid chromatography (LC) is introduced. An innovative Si@GO@βCD coated needle-sleeve extractant device was developed and then employed in the automated online SPME-LC-UV determination of estrogen-like isoflavones from human urine samples. The extractant SPME device is easily attachable at the endpoint of an analytical syringe needle and operated by a lab-made autosampler.

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β-Cyclodextrin, coupled to graphene oxide supported on aminopropyl silica, was synthesized and characterized. This material was combined with microextraction by packed sorbent to act as the sample preparation step. The analytical method optimization was carried out by employing experimental design and had its figures of merit determined.

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Since its discovery in 2004 by Novoselov et al., graphene has attracted increasing attention in the scientific community due to its excellent physical and chemical properties, such as thermal/mechanical resistance, electronic stability, high Young's modulus, and fast mobility of charged atoms. In addition, other remarkable characteristics support its use in analytical chemistry, especially as sorbent.

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Kirschner wires (K wires) are a common fixation device in foot and ankle surgery, particularly in lesser-toe fixation. Fatigue failure is a known complication of this fixation. The material properties of the K wire are a factor in the strength and durability of the wire.

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Material processing has become essential for the proper control, tuning and consequent application of the properties of micro/nanoparticles. In this case, we report herein the capability of the microwave-assisted hydrothermal (MAH) method to prepare the SrTiO3 compound, as a case study of inorganic compounds. Analyses conducted by X-ray diffraction, X-ray photoelectron and X-ray absorption spectroscopies confirmed that the MAH route enables the formation of pristine SrTiO3.

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Two kinds of flexible ozone (O) sensors were obtained by placing pristine ZnO nanorods and gold-modified ZnO nanorods (NRs) on a bi-axially oriented poly(ethylene terephthalate) substrate. The chemiresistive sensor is operated at typically 1 V at room temperature under the UV-light illumination. The ZnO nanorods were prepared via a hydrothermal route and have a highly crystalline wurtzite structure, with diameters ranging between 70 and 300 nm and a length varying from 1 to 3 μm.

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Road dust has been identified as one of the main sources of outdoor PM in Bogota (a Latin American megacity), but there are no studies that have analyzed the physicochemical characteristics and origins of its respirable fraction. A characterization of inorganic compounds (water soluble ions, major and trace elements, organic and elemental carbon) and an analysis of source contributions to the PM fraction of road dust were carried out in this study. A total of twenty road dust samples, selected from representative industrial, residential and commercial areas, were swept and resuspended to obtain the thoracic fraction.

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Facial nerve stimulation (FNS) after cochlear implant activation is a well-known side effect, with an incidence rate raging between 1% and 14.9%. Some causes of deafness have been associated with a higher incidence of this entity, however, there is still no consensus regarding its pathophysiological mechanisms.

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According to our research, this is the first case described in the literature of spontaneous intracranial epidural hematoma secondary to the use of Xareltor. Spontaneous intracranial epidural hematomas are rarely described in the literature. They are associated with infectious diseases of the skull, coagulation disorders, vascular malformations of the dura mater and metastasis to the skull.

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Soils around coal mining are important reservoir of hazardous elements (HEs), nanominerals, and ultrafine compounds. This research reports and discusses the soil concentrations of HEs (As, Cd, Cr, Cu, Ni, Pb, and Zn) in coal residues of abandoned mines. To assess differences regarding environmental impact and risk assessment between coal abandoned mines from the Santa Catarina state, eighteen coal cleaning rejects with different mineralogical and chemical composition, from eight abandoned mines were collected.

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Exposure to coal and coal ashes can cause harmful effects in in vitro and in vivo systems, mainly by the induction of oxidative damage. The aim of this work was to assess cytotoxic and genotoxic effects using the V79 cell line treated with coal and coal fly ash particles derived from a coal power plant located in Santa Catarina, Brazil. Two coal samples (COAL11 and COAL16) and two coal fly ash samples (CFA11 and CFA16) were included in this study.

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A detailed study of the structural, surface, and gas-sensing properties of nanostructured CoZnO films is presented. X-ray diffraction (XRD) analysis revealed a decrease in the crystallization degree with increasing Co content. The X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopies (XPS) revealed that the Co ions preferentially occupied the Zn sites and that the oxygen vacancy concentration increased as the amount of cobalt increased.

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Quercetin is a natural compound that has several biological activities including anticancer activity. However, the use of this drug has been limited mostly because of its poor water solubility and low bioavailability. Therefore, the development of quercetin-loaded nanocarrier systems may be considered a promising advance to exploit its therapeutic properties in clinical setting including cancer treatment.

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Aim: To compare a gel made with chamomile (Chamomilla recutita) with a cream of urea as an intervention to delay the time to occurrence of radiation dermatitis.

Background: Radiation dermatitis is one of the most common adverse effects of radiotherapy in patients with head and neck cancer. It is characterized by erythema, itching, pain, skin breakage and burning sensation, and there is no consensus on how to prevent it.

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Strontium titanate nanoparticles have attracted much attention due to their physical and chemical properties, especially as photocatalysts under ultraviolet irradiation. In this paper, we analyze the effect of heating rate during the crystallization process of SrTiO3 nanoparticles in the degradation of organic pollutants. The relationship between structural, morphological and photocatalytic properties of the SrTiO3 nanoparticles was investigated using different techniques.

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Detailed geochemistry similarities between the burning coal cleaning rejects (BCCRs) and non-anthropogenic geological environments are outlined here. While no visible flames were detected, this research revealed that auto-combustion existed in the studied area for many years. The occurrence of several amorphous phases, mullite, hematite and many other Al/Fe-minerals formed by high temperature was found.

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Brazilian coal area (South Brazil) impacted the environment by means of a large number of coal waste piles emplaced over the old mine sites and the adjacent areas of the Criciúma, Urussanga, and Siderópolis cities. The area studied here was abandoned and after almost 30 years (smokeless visual) some companies use the actual minerals derived from burning coal cleaning rejects (BCCRs) complied in the mentioned area for industry tiles or refractory bricks. Mineralogical and geochemical similarities between the BCCRs and non-anthropogenic geological environments are outlined here.

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Ultrafine and nanometric sediment inputs into river systems can be a major source of nutrients and hazardous elements and have a strong impact on water quality and ecosystem functions of rivers and lakes regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in South America. The objective of this work was to study the coal cleaning rejects (CCRs) spill that occurred from a CCRs impoundment pond into the Tubarão River, South Brazil, provided a unique occasion to study the importance and role of incidental nanoparticles associated with pollutant dispersal from a large-scale, acute aquatic pollution event.

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The sulfide oxidation and precipitation of Al-Fe-secondary minerals associated with abandoned acid mine drainage (AMD) from the abandoned copper mine waste pile at Touro, Spain, has been studied by sequential extraction (SE) combined with several techniques with the intent of understanding the role of these processes play in the natural attenuation of hazardous element contaminants in the AMD. In addition, the fragile nature of nanominerals and ultrafine particle (UFP) assemblages from contaminated sediment systems from the abandoned copper mine required novel techniques and experimental approaches. The investigation of the geochemistry of complex nanominerals and UFP assemblages was a prerequisite to accurately assess the environmental and human health risks of contaminants and cost-effective chemical and biogeological remediation strategies.

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