Antonio Cid-Samamed | Universidade de Vigo (original) (raw)

Papers by Antonio Cid-Samamed

Molecules, 2019

Heliyon, 2017

The kinetic bioconcentration of N-heterocyclic aromatic hydrocarbons and polycyclic aromatic hydr... more The kinetic bioconcentration of N-heterocyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons in mussels (Mytilus galloprovincialis) after short waterborne exposure was studied. Benzo[a]pyrene (BaP), its analogue azaarene 10-azabenzo[a]pyrene (AzaBaP), and their mixture (Mix), were selected to monitor the changes in water concentrations over three days. Decay of both PAHs concentrations in water after 24 h of waterborne exposure to mussels at levels of 10 and 100 μg/L follows a first order kinetic with half-lives of 4-5 h, with residual levels of PAHs below 7%. While steady-state scenarios are well studied, there is a lack of information of what happens under non-steady-state conditions, the main purpose of our paper. A synergistic bioconcentration of the mixture was found (around 800 in the mix vs. around 400 for individual PAHs at 100 μg/L of waterborne exposure). It could be explained by the following reasons. The most polar AzaBaP does not compete with the most non-polar BaP for the same tissue

Cyclodextrin - A Versatile Ingredient

The essential oils normally had low physicochemical stability and low solubility in water. These ... more The essential oils normally had low physicochemical stability and low solubility in water. These facts limit their industrial applications in general and in food formulations particularly. This chapter characterizes the physicochemical properties and the antioxidant and antimicrobial activities of three encapsulated essential oils-guava leaf, yarrow and black pepper essential oils-in hydroxypropyl-β-cyclodextrin (HPβCD).

Properties and Uses of Microemulsions, 2017

In this chapter, the ability of artificial neural networks was evaluated to predict the influence... more In this chapter, the ability of artificial neural networks was evaluated to predict the influence of amphiphiles as additive upon the electrical percolation of dioctyl sodium sulfosuccinate (AOT)/isooctane/water microemulsions. In particular, water/AOT/isooctane microemulsion behaviour has been modelled. These microemulsions have been developed in presence of 1-n-alcohols, 2-n-alcohols, n-alkylamines and n-alkyl acids. In all cases, a neural network has been obtained to predict with accuracy the experimental behaviour to identify the physico-chemical variables (such as additive concentration, molecular mass, log P, pK a or chain length) that exert a greater influence on the model. All models are valuable tools to evaluate the percolation temperature for AOT-based microemulsions.

Journal of Molecular Liquids, 2016

Abstract Percolative behaviour of w/o AOT/iC8/H2O microemulsions added with different n-alkanols ... more Abstract Percolative behaviour of w/o AOT/iC8/H2O microemulsions added with different n-alkanols is reported. 1-n-alcohols and 2-n-alkanols presented dissimilarities affecting percolation. Smaller alcohols ease percolation, especially at low concentrations. Greater molecules implied a reinforcement of the surfactant film that delayed the percolation threshold. Also, a neural network based simulation model of the phenomenon has been developed. This single model has only five input variables and can estimate percolation temperature of microemulsions added with the two types of alcohols studied, with an RMSE of 0.98 °C and R2 = 0.9740 (validation dataset values). This is considered a successful prediction rate, following previous developments with other families of additives, that confirms neural networks as reliable tools for percolative behaviour modelling.

ACS Omega, 2017

This work aims at assessing the influence of two different solvents, bidistilled water and toluen... more This work aims at assessing the influence of two different solvents, bidistilled water and toluene, on dispersions of carbon-based engineered nanomaterials, namely, fullerenes, and their self-assembly behavior. The obtained self-assembled carbon-based materials were characterized using UV−vis spectrophotometry and transmission electron microscopy techniques. The results obtained were unexpected when toluene was used for dispersing fullerene C 60 , with the formation of two different types of self-assembled structures: fullerene C 60 nanowhiskers (FNWs) and a type of quasispherical nanostructure. The FNWs ranged between 1 and 6 μm in length, whereas the quasispherical fullerene C 60 nanoaggregates ranged between 10 and 50 nm in diameter. Aggregates obtained in toluene showed a well-formed crystal structure. When using water, the obtained aggregates were amorphous and showed a no well-defined shape. Their sizes ranged between 20 and 40 nm for nanosized structures and between 0.4 and 4.8 μm for micron-sized self-aggregates.

Tenside Surfactants Detergents

The influence of alkyl-aldehydes upon electric percolation of AOT-based microemulsions has been s... more The influence of alkyl-aldehydes upon electric percolation of AOT-based microemulsions has been studied. The number of carbons in the hydrocarbon chain was varied between 0 and 5 atoms (chain length between 0 and 7.33 Å). Two different behaviors were found, while the presence in the microemulsion of short chains aldehydes implies a decrease in the percolation temperature, aldehydes with 4 or 5 carbon atoms in the hydrocarbon chain increase the percolation threshold. This opposite behavior has been justified in terms of aldehyde location in the microheterogeneous system.

International Journal of Environmental Research and Public Health

Geoscience Communication Discussions

We present a laboratory technique that can be used to measure tropospheric ozone, following a tra... more We present a laboratory technique that can be used to measure tropospheric ozone, following a traditional method developed by Christian Friedrich Schönbein in the 19 th century. The practice is described with two levels of complexity (the advanced level includes the production in the lab of paper strips as they were produced in the 19 th century while the basic level does not), and is suitable for use by both high-school and first-year undergraduate students. The overall aim is to familiarise students with both the scientific methods involved and the related concepts of pollution and ozone. This technique was developed and presented in high schools during a communication campaign to celebrate the annual Galician Scientist Day and based on the detected need for a better understanding of the problems of climate change and pollution. Moreover, we discuss the teaching approach used and the results obtained from surveys and feedback obtained from the students and teachers. 1 Introduction Usually, the study of the atmosphere at this educational levels and from the practical point of view is focused at best on the use of cheap and small weather stations that measure physical variables (e.g. temperature, pressure, humidity). However the study of the atmosphere and the environment needs of knowledge on its chemical composition. For example, global warming and ozone depletion are issues broadly taught but mostly from a theoretical approach (documentaries, lectures...). That said, this laboratory practice introduces a hands-on approach to the study of the chemical composition of the atmosphere, letting the students be much more familiar with it. This laboratory practice is intended as an additional tool to assist in the teaching of atmosphere and environment science. Thus it is presented as project-based learning with proven competence, as defended in previous works (Blumenfeld et al., 1991; Bell, 2010). Using this learning method, students developed their skills through "learning-by-doing".

Microemulsions are self-aggregated colloidal systems that provide a controllable system with a pr... more Microemulsions are self-aggregated colloidal systems that provide a controllable system with a promising application as nanoreactors: they can act as pools within which the properties of the nanoparticles can be controlled without difficulty. So in this chapter, I will deal with the metal NPs synthesized by the microemulsion method. This method allows in some cases to control the properties of size, shape, and crystal structure of the metallic NPs, thus generating with the same reagents a series of seeds of different shapes and sizes. The control of the reaction time, the temperature, and the reaction conditions will give us a production of different geometries that will find different applications in large range of research fields.

Microemulsion - a Chemical Nanoreactor [Working Title]

The kinetic behaviours in microemulsions can be easily modelled using an extension of the pseudop... more The kinetic behaviours in microemulsions can be easily modelled using an extension of the pseudophase model previously developed for micellar catalysis. This model considers that the microheterogeneous media can be considered as the sum of different conventional reaction media, where the reagents are distributed and in which the reaction can occur simultaneously. The reaction rate observed in the microheterogeneous system will be the sum of the velocities in each one of the pseudophases. This use can be considered as an extension of the pseudophase model, which has been developed for the quantitative analysis of nitrosation reactions in AOT/isooctane/water microemulsions and has been applied successfully in the literature in a large variety of chemical reactions.

Journal of Inorganic and Organometallic Polymers and Materials volume 30, pages1011–1032, 2020

In recent decades, the industrial use of nanoparticles (NPs) and, especially, metal nanoparticles... more In recent decades, the industrial use of nanoparticles (NPs) and, especially, metal nanoparticles (MNPs), has attracted widespread attention because of their special physicochemical properties. The ability of MNPs to self-arrange into ordered, nanometrically sized structures and form nanometric colloids has enabled their use as nanocatalysts the properties of which can be tailored through ordered growth of their crystal structures. In fact, these nanocatalysts provide a unique opportunity to tune material properties at the nanometric scale. Thus, altering the size or shape of the nanoparticles allows materials of identical composition but different properties to be obtained. The versatility of MNPs (and, especially, those containing the transition metals copper, nickel and palladium) led us to review their synthetic procedures, most salient physicochemical properties, and existing and potential applications (chemical sensing and plasmon resonance included).

International Journal of Environmental Research and Public Health, 2020

The exponential growth of nanotechnology has led to the production of large quantities of nanomat... more The exponential growth of nanotechnology has led to the production of large quantities of nanomaterials for numerous industrial, technological, agricultural, environmental, food and many other applications. However, this huge production has raised growing concerns about the adverse effects that the release of these nanomaterials may have on the environment and on living organisms. Regarding the effects of QDs on aquatic organisms, existing data is scarce and often contradictory. Thus, more information is needed to understand the mechanisms associated with the potential toxicity of these nanomaterials in the aquatic environment. The toxicity of QDs (ZnS and CdS) was evaluated in the freshwater fish Danio rerio. The fishes were exposed for seven days to different concentrations of QDs (10, 100 and 1000 µg/L) individually and combined. Oxidative stress enzymes (catalase, superoxide dismutase and glutathione S-transferase), lipid peroxidation, HSP70 and total ubiquitin were assessed. In general, results suggest low to moderate toxicity as shown by the increase in catalase activity and lipid peroxidation levels. The QDs (ZnS and CdS) appear to cause more adverse effects singly than when tested combined. However, LPO results suggest that exposure to CdS singly caused more oxidative stress in zebrafish than ZnS or when the two QDs were tested combined. Levels of Zn and Cd measured in fish tissues indicate that both elements were bioaccumulated by fish and the concentrations increased in tissues according to the concentrations tested. The increase in HSP70 measured in fish exposed to 100 µg ZnS-QDs/L may be associated with high levels of Zn determined in fish tissues. No significant changes were detected for total ubiquitin. More experiments should be performed to fully understand the effects of QDs exposure to aquatic biota.

Geosci. Commun., 3, 99–108, 2020

We present a laboratory technique to measure tro-pospheric ozone, following a traditional method ... more We present a laboratory technique to measure tro-pospheric ozone, following a traditional method developed by Christian Friedrich Schönbein in the 19th century. The aim is to familiarise students with both the scientific method and the concepts of pollution and climate change, taking advantage of the possibilities of a very cheap hands-on approach over other existing theoretical ones. Also, this teaching activity can help the students to understand the differences between objective and subjective analysis. Moreover, they can make effective use of new technologies and photography. We include a description of how to conduct the lesson at two different levels of complexity (advanced and basic) to allow us to adapt it to the capacity of the students. The advanced level includes the production in the lab of paper strips as they were produced in the 19th century, whilst the basic level does not. This practice is suitable for use by both high school and first-year undergraduate students and was presented in high schools during a communication campaign to celebrate the annual Galician Scientist Day. We evaluate the teaching approach used through the results from collected surveys and feedback received from the students and teachers .

molecules, 2019

Micellar systems consisting of a surfactant and an additive such as an organic salt or an acid us... more Micellar systems consisting of a surfactant and an additive such as an organic salt or an acid usually self-organize as a series of worm-like micelles that ultimately form a micellar network. The nature of the additive influences micellar structure and properties such as aggregate lifetime. For ionic surfactants such as sodium dodecyl sulfate (SDS), CMC decreases with increasing temperature to a minimum in the low-temperature region beyond which it exhibits the opposite trend. The presence of additives in a surfactant micellar system also modifies monomer interactions in aggregates, thereby altering CMC and conductance. Because the standard deviation of β was always lower than 10%, its slight decrease with increasing temperature was not significant. However, the absolute value of Gibbs free enthalpy, a thermodynamic potential that can be used to calculate the maximum of reversible work, increased with increasing temperature and caffeic acid concentration. Micellization in the presence of caffeic acid was an endothermic process, which was entropically controlled. The enthalpy and enthropy positive values resulted from melting of "icebergs" or "flickering clusters" around the surfactant, leading to increased packing of hydrocarbon chains within the micellar core in a non-random manner. This can be possibly explained by caffeic acid governing the 3D matrix structure of water around the micellar aggregates. The fact that both enthalpy and entropy were positive testifies to the importance of hydrophobic interactions as a major driving force for micellization. Micellar systems allow the service life of some products to be extended without the need to increase the amounts of post-harvest storage preservatives used. If a surfactant is not an allowed ingredient or food additive, carefully washing it off before the product is consumed can avoid any associated risks. In this work, we examined the influence of temperature and SDS concentration on the properties of SDS-caffeic acid micellar systems. Micellar properties can be modified with various additives to develop new uses for micelles. This allows smaller amounts of additives to be used without detracting from their benefits.