Papers by PATRICIO ROBERTO LOPEZ EXPOSITO
Journal of Biotechnology, Feb 1, 2017
Fast and reliable methods to determine biomass concentration are necessary to facilitate the larg... more Fast and reliable methods to determine biomass concentration are necessary to facilitate the large scale production of microalgae. A method for the rapid estimation of Chlorella sorokiniana biomass concentration was developed. The method translates the suspension particle size spectrum gathered though laser reflectance into biomass concentration by means of two machine learning modelling techniques. In each case, the model hyper-parameters were selected applying a simulated annealing algorithm. The results show that dry biomass concentration can be estimated with a very good accuracy (R 2 = 0.87). The presented method seems to be suited to perform fast estimations of biomass concentration in suspensions of microalgae cultivated in moderately turbid media with tendency to aggregate.
Carbohydrate Polymers, Feb 1, 2021
In-depth characterization of the aggregation state of cellulose nanocrystals through analysis of ... more In-depth characterization of the aggregation state of cellulose nanocrystals through analysis of transmission electron microscopy images Cristina Campano (Conceptualization) (Methodology) (Validation) (Formal analysis) (Investigation) (Data curation) (Writing-original draft) (Visualization), Patricio Lopez-Exposito (Conceptualization) (Methodology) (Software) (Validation) (Formal analysis) (Investigation) (Data curation) (Writing-review and editing) (Visualization), Laura Gonzalez-Aguilera (Methodology) (Validation) (Investigation) (Data curation) (Visualization),Ángeles Blanco (Resources) (Writing-review and editing) (Supervision) (Project administration) (Funding acquisition), Carlos Negro (Resources) (Writing-review and editing) (Supervision) (Project administration) (Funding acquisition)
Algal Research-Biomass Biofuels and Bioproducts, Dec 1, 2017
Flocculation followed by settling is gaining momentum as a means to concentrate microalgal biomas... more Flocculation followed by settling is gaining momentum as a means to concentrate microalgal biomass due to the low investment and operation costs of the process. Microalgal flocculation can be further optimized by knowing the relationship between the hydrodynamic conditions applied in the process and the geometric properties of the flocs, namely characteristic size and fractal dimension, D f , given that settling rate is highly dependent on these two parameters. Current methods to characterize the geometry of flocs rely on estimating the 2D fractal dimension from microscopic images, which may result in inaccuracies caused by the overlapping or superimposition of aggregate structures prompted when the image of a 3D object is projected a on the plane, and due to the fact that the estimation performed is dependent on the orientation of the particle during image acquisition. The present paper describes a new procedure to estimate D f of Chlorella sorokiniana aggregates by correlating the 2D fractal dimension of the real aggregates microscopic images with the 2D fractal dimensions of computer generated flocs of prescribed 3D geometry. This procedure avoids the inaccuracies entailed with floc imaging and those due to the random orientation of the floc during image acquisition.
Nanomaterials, 2021
The present paper proposes a novel approach for the morphological characterization of cellulose n... more The present paper proposes a novel approach for the morphological characterization of cellulose nano and microfibers suspensions (CMF/CNFs) based on the analysis of eroded CMF/CNF microscopy images. This approach offers a detailed morphological characterization and quantification of the micro and nanofibers networks present in the product, which allows the mode of fibrillation associated to the different CMF/CNF extraction conditions to be discerned. This information is needed to control CMF/CNF quality during industrial production. Five cellulose raw materials, from wood and non-wood sources, were subjected to mechanical, enzymatic, and (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO)-mediated oxidative pre-treatments followed by different homogenization sequences to obtain products of different morphologies. Skeleton analysis of microscopy images provided in-depth morphological information of CMF/CNFs that, complemented with aspect ratio information, estimated from gel point data, ...
El proyecto consistio en la presentacion del prototipo Chem-E-Car desarrollado en la UCM en la co... more El proyecto consistio en la presentacion del prototipo Chem-E-Car desarrollado en la UCM en la competicion mundial que se celebro durante el transcurso del Congreso Mundial de Ingenieria Quimica (Barcelona, 30 septiembre-2 de octubre de 2017).
El objetivo principal de este proyecto es la preparacion de grupos de alumnos para la concepcion ... more El objetivo principal de este proyecto es la preparacion de grupos de alumnos para la concepcion y diseno de un prototipo teorico de Chem-E-Car, que cumpla todos los estandares del concurso Chem-E-Car organizado por AIChE, utilizando el material docente y las bases para la competicion desarrollados por el equipo investigador en el PIMCD 103 de la convocatoria 2014. Para ello se ha llevado a cabo las siguientes actividades: • Se preparo y celebro un seminario en marzo de 2015 para informar a los alumnos sobre el concurso Chem-E-Car y sobre el material desarrollado en el PIMCD 103 de 2014. • Se formaron dos equipos de trabajo multidisciplinares con alumnos de distintos cursos de los grados de Ingenieria Quimica y de Ingenieria de Materiales. Cada equipo selecciono un capitan y un tutor miembro del equipo del presente proyecto de innovacion docente, para guiar a los alumnos. Los alumnos participantes han tenido a su disposicion los laboratorios y material del departamento de Ingenieria...
Colloids and Surfaces B: Biointerfaces, 2019
This paper investigates the flocculation of Chlorella sorokiniana suspensions with a novel cellul... more This paper investigates the flocculation of Chlorella sorokiniana suspensions with a novel cellulose derivative, namely hairy cationic nanocrystalline cellulose (CNCC). CNCC are a brand new family of nanocellulose characterized by having two positively charged amorphous ends joint through a common crystalline shaft. Flocculation was monitored through laser reflectance and its mechanism was studied by means of zeta potential, fractal dimension and turbidity removal. CNCC dosage and shear rate were varied and their effect on floc morphology and filterability were assessed. CNCC effectively flocculated the cultures at dosages well below and over the isoelectric point, being the flocculation mechanisms and floc strength highly dependent on the doses applied. The filtration propensity of flocculated suspensions proved highly sensitive to small differences in flocs' geometry. The aggregation process entailed two phases, a first one in which the CNCC adsorbed on the surface of microalgal cells according to a flat random deposition up to reaching a maximal cell coverage, and a second one in which the free spots left were progressively covered with orthogonally deposited CNCC, being this later configuration the main responsible for intercellular attachment. The present work demonstrates that CNCC is an effective flocculant of microalgal cell suspensions and constitutes an alternative worth exploring for the aggregation of other cells' suspensions.
Journal of Colloid and Interface Science, 2019
Hypothesis: The present paper investigates, for the first time, the potential of cationic hairy c... more Hypothesis: The present paper investigates, for the first time, the potential of cationic hairy cellulose nanocrystals (CNCC) to induce the flocculation of a model suspension of kaolinite. CNCC belong to a brand new family of nanocelluloses characterized for presenting a crystalline rod-like body and functionalized amorphous chains at both ends. Given that these chains can be easily tuned, these nanocelluloses present a high potential as fit-to-purpose flocculants. Experiments: CNCC were produced through periodate oxidation, cationization and thermal treatment of cellulose. Flocculation was monitored by both photometric dispersion analysis and laser reflectance. Flocs were characterized by the determination of zeta potential, supernatant turbidity removal and optical microscopy. A recently developed machine learning random forest regression model was used to estimate fractal dimension (D f) from chord length distribution data. Findings: Although a high efficiency was achieved for CNCC dosages between 7.5 and 75 mg/g, the maximum floc size and the fastest flocculation were found near the isoelectric point (10-30 mg/g). Thus, CNCC acted through charge neutralization mechanism. The model used to estimate flocs D f was found very successful to describe the flocculation process. The clay/CNCC flocs D f values suggest a relation between floc conformation and CNCC dosage, presenting an opener structure when closer to the isoelectric point.
Algal Research, 2019
The pre-concentration of microalgal cultures through flocculation can be applied to reduce the ha... more The pre-concentration of microalgal cultures through flocculation can be applied to reduce the harvesting costs of biomass. The microalgal flocs induced through flocculation must have the optimal size and geometry to enhance the performance of subsequent concentration operations. In this work, we propose a new method to estimate the average fractal dimension of Chlorella sorokiniana flocs based on correlating the suspension chord length distribution with the flocs average geometry through a machine learning random forest regression model. To obtain the data required for training the machine learning model, a set of virtual flocs of prescribed fractal dimension was generated through a computer software. The virtual flocs were subject to chord length data acquisition by means of another piece of software simulating the operation of a focused beam reflectance probe. With the chord length data generated the random forest regression model was trained and optimized and then satisfactorily validated with data of real suspensions of known average geometry. The method developed may be used to implement flocculation control systems capable of adjusting the geometry of flocs to the requirements of subsequent concentration operations by actuating on the process stirring intensity.
Algal Research, 2017
Flocculation followed by settling is gaining momentum as a means to concentrate microalgal biomas... more Flocculation followed by settling is gaining momentum as a means to concentrate microalgal biomass due to the low investment and operation costs of the process. Microalgal flocculation can be further optimized by knowing the relationship between the hydrodynamic conditions applied in the process and the geometric properties of the flocs, namely characteristic size and fractal dimension, D f , given that settling rate is highly dependent on these two parameters. Current methods to characterize the geometry of flocs rely on estimating the 2D fractal dimension from microscopic images, which may result in inaccuracies caused by the overlapping or superimposition of aggregate structures prompted when the image of a 3D object is projected a on the plane, and due to the fact that the estimation performed is dependent on the orientation of the particle during image acquisition. The present paper describes a new procedure to estimate D f of Chlorella sorokiniana aggregates by correlating the 2D fractal dimension of the real aggregates microscopic images with the 2D fractal dimensions of computer generated flocs of prescribed 3D geometry. This procedure avoids the inaccuracies entailed with floc imaging and those due to the random orientation of the floc during image acquisition.
Journal of Biotechnology, 2017
Fast and reliable methods to determine biomass concentration are necessary to facilitate the larg... more Fast and reliable methods to determine biomass concentration are necessary to facilitate the large scale production of microalgae. A method for the rapid estimation of Chlorella sorokiniana biomass concentration was developed. The method translates the suspension particle size spectrum gathered though laser reflectance into biomass concentration by means of two machine learning modelling techniques. In each case, the model hyper-parameters were selected applying a simulated annealing algorithm. The results show that dry biomass concentration can be estimated with a very good accuracy (R 2 = 0.87). The presented method seems to be suited to perform fast estimations of biomass concentration in suspensions of microalgae cultivated in moderately turbid media with tendency to aggregate.
Journal of Applied Phycology, 2015
A novel method to estimate the concentration of Chlamydomonas reinhardtii biomass was developed. ... more A novel method to estimate the concentration of Chlamydomonas reinhardtii biomass was developed. The method employs the chord length distribution information gathered by means of a focused beam reflectance probe immersed in the culture sample and processes the data through a feedforward multilayer perceptron. The multilayer perceptron architecture was systematically optimised through the application of a simulated annealing algorithm. The method developed can predict the concentration of microalgae with acceptable accuracy and, with further development, it could be implemented online to monitor the aggregation status and biomass concentration of microalgal cultures.
El proyecto consiste en construir un prototipo de coche “Chem-E-Car” y constituir a la UCM como u... more El proyecto consiste en construir un prototipo de coche “Chem-E-Car” y constituir a la UCM como una de las primeras universidades espanolas que participa en dicha competicion internacional.
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Papers by PATRICIO ROBERTO LOPEZ EXPOSITO