BUSCADOR RECOLECTA

[EN] The development of flat acoustic lenses for different applications such as biomedical engineering is a topic of great interest. Flat lenses like Fresnel Zone Plates (FZPs) are capable of focusing energy beams without the need of concave or convex geometries, which are more difficult to manufacture. One of the possible applications of these type of lenses is tumor ablation through High Intensity Focused Ultrasound (HIFU) therapies with real time Magnetic Resonance Imaging (MRI) monitoring. In order to be MRI compatible, the FZP material cannot have electromagnetic interaction. In this work, a Phase-Reversal FZP (PR-FZP) made of Polylactic Acid (PLA) manufactured with a commercial 3D printer is proposed as a better, more efficient and MRI compatible alternative to conventional Soret FZPs. Phase-Reversal lenses, unlike traditional FZPs, take advantage of all the incident energy by adding phase compensation regions instead of pressure blocking regions. The manufactured PR-FZP achieves 21.9 dB of focal gain, which increases the gain compared to a Soret FZP of its same size by a factor of 4.0 dB. Both numerical and experimental results are presented, demonstrating the improved focusing capabilities of these types of lenses., This work has been supported by Spanish MINECO (TEC2015-70939-R). S.P.-L. acknowledges financial support from Universitat Politècnica de València through grant program PAID-01-18.

[EN] In this work, we present a bifocal Fresnel zone plate (BiFZP) capable of generating focusing profiles with two different foci. The performance of the BiFZP is demonstrated in the ultrasound domain, with a very good agreement between the experimental measurements and the finite element method (FEM) simulations. This lens becomes an appealing alternative to other dual-focusing lenses,in which the foci location can only be set at a limited range of positions, such as M-bonacci zone plates. Moreover, the variation of the operating frequency has also been analyzed, providing an additional dynamic control parameter in this type of lenses., This work was supported by the Spanish MICINN RTI2018-100792-B-I00 project. S.P.-L. acknowledges financial support from the Universitat Politècnica de València grant program PAID-01-18. D.T.-S. acknowledges financial support from the MICINN BES-2016-07713 project.

[EN] In this work, we present a lens based on a thin hollow ABS spherical container structure, which can be filled up with different compatible liquids. The acoustic jet can be dynamically shaped by either shifting the operating frequency or modifying the geometry of the lens. We show for the first time that a spherical Ethanol ABS core¿shell acoustical lens immersed in water with low diameter-to-wavelength ratio equal to 6.67 and refraction index of 1.24 achieves a focusing spot narrower than 0.85¿. Experimental measurements validate simulation results and demonstrate the viability of these configurable spherical lenses in underwater acoustic focusing applications., This work has been supported by Spanish MINECO
TEC2015-70939-R and MICINN RTI2018-100792-B-I00 projects. S.P.-L. acknowledges
financial support from Universitat Politècnica de València grant
program PAID-01-18. I.V.M. and O.V.M. acknowledge the Tomsk Polytechnic
University Competitiveness Enhancement Program.

[EN] This work analyzes the influence of the distribution of transparent Fresnel regions over the focusing profile of Soret Zone Plates. It is shown that this effect becomes very significant in those fields where directional transducers are employed, such as microwaves or acoustics. A thorough analysis on both the lens transmission efficiency and the focusing enhancement factor is presented. Moreover, experimental measurements are also carried out, validating the theoretical model and demonstrating that the distribution of transparent Fresnel regions becomes a critical parameter in applications requiring directional emitters., This work was supported by Spanish MINECO TEC2015-70939-R and MICINN RTI2018-100792-B-I00 projects. S.P.-L. acknowledges financial support from Universitat Politecnica de Valencia Grant Program No. PAID-01-18.

[EN] Over the recent years, subwavelength grating (SWG) structures have increasingly attracted attention in the area of evanescent-field photonic sensors. In this Letter, for the first time
to the best of our knowledge, we demonstrate experimentally
the real-time refractive index (RI) sensing using the SWG
bimodal interferometric structures. Two different configurations are considered to compare the effect of the nonlinear
phase shift, obtained between the two first transverse electromagnetic propagating modes, in the measured bulk sensitivity. Very high experimental values up to 2270 nm/RIU are
reached, which perfectly match the numerical simulations
and significantly enhance other existing SWG and spectralbased sensors. By measuring the spectral shift, the obtained
experimental sensitivity does not depend on the sensor
length. As a result, a highly sensitive and compact singlechannel interferometer is experimentally validated for refractive index sensing, thus opening new paths in the field of
optical integrated sensors., European Commission (PHC-634013 PHOCNOSIS project); Spanish Government (TEC2015-63838-C3-1-R-OPTONANOSENS project); Universitat Politecnica de Valencia (grant PAID 01-18).

[EN] Tomato chlorotic dwarf viroid (TCDVd) is a pospiviroid that causes severe disease symptoms in tomato. TCDVd is also naturally found in other crops and plants, in most occasions being asymptomatic. Apart from the natural hosts reported up to now, artificial inoculations have revealed that TCDVd can infect other plants, including eggplant (Solanum melongena). In a screening of seedlings of eggplant from a breeding programme we detected a pospiviroid, which we identified as TCDVd, representing the first report of natural infection of eggplant by TCDVd. The new TCDVd isolate of eggplant was detected by reverse transcription polymerase chain reaction (RT¿PCR) using primers TG21/CT20, initially designed to detect potato spindle tuber viroid. The new isolate sequence is close to a Brugmansia sanguinea isolate of TCDVd from the Netherlands, and most of the nucleotidic changes with respect to this isolate and to the reference genome sequence of TCDVd are found in the TR region. Naturally infected plants of eggplant with this TCDVd isolate did not display any disease symptoms. We demonstrated that in eggplant TCDVd is mechanically transmitted with low to moderate efficiency with cultivation practices, but not by plant¿to¿plant contact. Tomato plants artificially inoculated with the eggplant isolate of TCDVd tested positive for the presence of the viroid at 50¿days after inoculation, but did not display any disease symptoms. Seed transmission to germinated seedlings of eggplant was variable among progenies from infected plants, ranging from 7.7% to 100.0%. Disinfection of seeds with chemical treatments with sodium hypochlorite and trisodium phosphate solutions plus thermotherapy at 80°C for 24¿hr or 90°C for 6 hr was ineffective in reducing the rate of transmission by seed. We did not find evidence of horizontal transmission of TCDVd by pollen, but vertical transmission was highly efficient when healthy eggplant plants were pollinated with infected pollen. Our results indicate that asymptomatic infection of eggplant by TCDVd and high seed and pollen transmission rates may contribute to the spread of this viroid. The information we obtained is useful in order to implement measures for the prevention, control and eradication of TCDVd in eggplant crops, as well as to avoid their transmission to other hosts., P.G. is grateful to Universitat Politècnica de València and to Japan Society for the Promotion of Science for their respective postdoctoral grants (PAID-10-18 and FY2019 JSPS Postdoctoral Fellowship for Research in Japan [Standard]). A.A. and D.A. are grateful to Universitat Politècnica de València for their respective predoctoral (PAID-01-18 and PAID-01-16) contracts within the Programa de Ayudas de Investigación y Desarrollo initiative. E.G.-F. is grateful to Ministerio de Educación, Cultura y Deporte para la Formación de Profesorado Universitario for a predoctoral grant (FPU17/02389). G.M. is grateful to Generalitat Valenciana for a predoctoral grant within the Santiago Grisolía programme (GRISOLIAP/2016/012). M.P. is grateful to Generalitat Valenciana and Fondo Social Europeo for a postdoctoral grant (APOSTD/2018/014).

[EN] Framed within the approach of a circular economy, this doctoral thesis studies the possibilities on the use of agricultural by-products for the manufacture of materials that could potentially replace polymers of petrochemical origin in the food packaging sector.

In this thesis different by-products from the flax industry have been studied to develop and subsequently characterize composite materials with high environmental performance. For this, a biodegradable polymer has been used in addition to flax by-products as a matrix for said composite materials. The polymer used is polylactic acid (PLA).

The flax by-products that have been used have been both in the form of filler / particulate materials and additives. Thus, short flax fiber and flax seed meal particles have been used as reinforcement materials in green composites with a PLA matrix: On the other hand, two types of chemically modified flax oil (epoxidized flax oil-ELO , and maleinized flax oil-MLO) have been used as plasticizers and / or compatibilizing agents in both parts of the work. In order to carry out a comparative analysis, other compatibilizing techniques were used to improve the interaction between the matrix and the reinforcing materials. To this end, in the different phases of this work, treatments with particle silanes, alkalinization, reactive extrusion with an epoxide-ESAO oligomer and with a styrene-methacrylate-PS-co-GMA copolymer have been used.

Furthermore, the initial phase of this thesis consists of verifying the positive effect that MLO has when it is used as additives in PLA matrix composites. After checking this effect, a second stage consisted of optimizing the percentage in which it can be included in the formulation. The composite material developed for this previous study consists of a PLA matrix with a fixed content of Diatomaceous Earth.

On the other hand, due to the nature of the thesis, focused on sustainability and the study of innovative ways of revaluing resources of natural origin, a study of the recyclability of the materials developed was also carried out. To do this, the deterioration of the PLA matrix undergoing several re-processing cycles was studied, simulating the standard polymer recycling processes., [ES] Enmarcándose dentro del planteamiento de una economía circular, la presente tesis doctoral estudia las posibilidades sobre el aprovechamiento de subproductos agrícolas para la fabricación de materiales que potencialmente pudieran sustituir a los polímeros de origen petroleoquímico en el sector del envasado de alimentos.

En esta tesis se han estudiado distintos subproductos procedentes de la industria del lino para desarrollar y posteriormente caracterizar materiales compuestos con un alto rendimiento medioambiental. Para ello se ha empleado además de los subproductos del lino, un polímero biodegradable como matriz de dichos materiales compuestos. El polímero empleado es el ácido poliláctico (PLA).

Los subproductos del lino que se han empleado han sido tanto en forma de materiales de relleno/partículas, como de aditivos. De este modo, se ha empleado fibra corta de lino y partículas de harina de semilla de lino como materiales de refuerzo en green composites con matriz de PLA: Por otro lado, dos tipos de aceite de lino modificado químicamente (aceite epoxidado de lino-ELO, y aceite maleinizado de lino-MLO) se han empleado como plastificantes y/o agentes compatibilizantes en ambas partes del trabajo. Para poder llevar a cabo un análisis comparativo, otras técnicas de compatibilizan se emplearon para mejorar la interacción entre la matriz y los materiales de refuerzo. Con este fin, en las distintas fases de este trabajo se han empleado tratamientos con silanos de las partículas, alcalinización, extrusión reactiva con un oligómero epóxido-ESAO y con un copolimero estireno-metacrilato-PS-co-GMA.

Además, la fase inicial de dicha tesis consiste en la comprobación del efecto positivo que ejerce el MLO cuando se emplea como aditivos en materiales compuestos de matriz de PLA. Tras la comprobación de dicho efecto, una segunda etapa consistió en la optimización del porcentaje en que este se puede incluir en la formulación. El material compuesto desarrollado para este estudio previo consiste en una matriz de PLA con un contenido fijo de Tierra de Diatomeas.

Por otro lado, debido a la naturaleza de la tesis, enfocada hacia las sostenibilidad y estudio de vías novedosas de re valorización de recursos de origen natural, se llevó también a cabo un estudio de la reciclabilidad de los materiales desarrollados. Para ello se estudió el deterioro que supone en la matriz de PLA el sometimiento a varios ciclos de re procesado, simulando los procesos estándares de reciclado de polímeros., [CA] Emmarcant-se dins del plantejament d'una economia circular, la present tesi doctoral estudia les possibilitats sobre l'aprofitament de subproductes agrícoles per a la fabricació de materials que potencialment pogueren substituir als polímers d'origen *petroleoquímico en el sector de l'envasament d'aliments. En aquesta tesi s'han estudiat diferents subproductes procedents de la indústria del lli per a desenvolupar i posteriorment caracteritzar materials compostos amb un alt rendiment mediambiental. Per a això s'ha emprat a més dels subproductes del lli, un polímer biodegradable com a matriu d'aquests materials compostos. El polímer empleat és l'àcid *poliláctico (PLA). Els subproductes del lli que s'han emprat han sigut tant en forma de materials de farcit/partícules, com d'additius. D'aquesta manera, s'ha emprat fibra curta de lli i partícules de farina de llavor de lli com a materials de reforç en *green *composites amb matriu de PLA: D'altra banda, dos tipus d'oli de lli modificat químicament (oli *epoxidado de lli-*ELO, i oli *maleinizado de lli-*MLO) s'han emprat com a plastificants i/o agents *compatibilizantes en totes dues parts del treball. Per a poder dur a terme una anàlisi comparativa, altres tècniques de compatibilitzen es van emprar per a millorar la interacció entre la matriu i els materials de reforç. A aquest efecte, en les diferents fases d'aquest treball s'han emprat tractaments amb *silanos de les partícules, *alcalinización, extrusió reactiva amb un *oligómero *epóxido-*ESAO i amb un *copolimero estiré-metacrilat-PS-*co-*GMA. A més, la fase inicial d'aquesta tesi consisteix en la comprovació de l'efecte positiu que exerceix el *MLO quan s'empra com a additius en materials compostos de matriu de PLA. Després de la comprovació d'aquest efecte, una segona etapa va consistir en l'optimització del percentatge en què aquest es pot incloure en la formulació. El material compost desenvolupat per a aquest estudi previ consisteix en una matriu de PLA amb un contingut fix de Terra de Diatomees. D'altra banda, a causa de la naturalesa de la tesi, enfocada cap a les sostenibilitat i estudi de vies noves de re valorització de recursos d'origen natural, es va portar també a cap un estudi de la *reciclabilidad dels materials desenvolupats. Per a això es va estudiar la deterioració que suposa en la matriu de PLA el sotmetiment a diversos cicles de re processat, simulant els processos estàndard de reciclatge de polímers., This research was funded by the Ministry of Science, Innovation, and
Universities (MICIU) project number MAT2017-84909-C2-2-R. L. Quiles-Carrillo is
recipient of a FPU grant (FPU15/03812) from the Spanish Ministry of Education,
Culture, and Sports (MECD). D. Lascano acknowledges UPV for the grant received
though the PAID-01-18 program.

[EN] In the present work, green¿composites from a partially biobased epoxy resin (BioEP) reinforced with lignocellulosic particles, obtained from flax industry by¿products or wastes, have been manufactured by casting. In this study, the flaxseed has been crushed by two different mechanical milling processes to achieve different particle sizes, namely coarse size (CFF), and fine size (FFF) particle flaxseed flour, with a particle size ranging between 100¿220 ¿m and 40¿140 ¿m respectively. Subsequently, different loadings of each particle size (10, 20, 30, and 40 wt%) were mixed with the BioEP resin and poured into a mold and subjected to a curing cycle to obtain solid samples for mechanical, thermal, water absorption, and morphological characterization. The main aim of this research was to study the effect of the particle size and its content on the overall properties of composites with BioEP. The results show that the best mechanical properties were obtained for composites with a low reinforcement content (10 wt%) and with the finest particle size (FFF) due to a better dispersion into the matrix, and a better polymer¿particle interaction too. This also resulted in a lower water absorption capacity due to the presence of fewer voids in the developed composites. Therefore, this study shows the feasibility of using flax wastes from the seeds as a filler in highly environmentally friendly composites with a wood¿like appearance with potential use in furniture or automotive sectors., This research was funded by Spanish Ministry of Science, Innovation, and Universities (MICIU), project numbers MAT2017-84909-C2-2-R. This work was supported by the POLISABIO program grant number (2019-A02).
D. Lascano thanks Universitat Politècnica de València (UPV) for the grant received through
the PAID-01-18 program. D. Garcia-Garcia wants to thank Generalitat Valenciana (GVA) for their financial support
through a post-doctoral grant (APOSTD/2019/201). S. Rojas-Lema is a recipient of a Santiago Grisolía contract
(GRISOLIAP/2019/132) from GVA. L. Quiles-Carrillo wants to thank GV for his FPI grant (ACIF/2016/182) and
MECD for his FPU grant (FPU15/03812). Microscopy services at UPV are acknowledged for their help in collecting
and analyzing FESEM images.

[EN] Big data is a concept that has changed the way to analyse data and information in different environments such as industry and recently, in agriculture. It is used to describe a large volume of data (structured or unstructured data), which are difficult to obtain, process or parse using conventional technologies and tools like relational databases or conventional statistics, in a reasonable time for their insight. However, Big Data is applied differently in each area to take advantage of its potential and capabilities. Specially in agriculture that presents more demanding conditions due to its inherent uncertainty, so Big Data methods and models from other environments cannot be used straight away in this area. In this paper, we present a review/update of term Big Data and analyse the evolution and the role of Big Data in agriculture outlined the element of collaboration., All authors acknowledge the partial support of Project 691249, RUC-APS: Enhancing and implementing Knowledge based ICT solutions within high Risk and Uncertain Conditions for Agriculture Production Systems, funded by the EU under its funding scheme H2020-MSCA-RISE-2015; and the project "Development of an integrated maturity model for agility, resilience and gender perspective in supply chains (MoMARGE). Application to the agricultural sector." Ref. GV/2017/025 funded by the Generalitat Valenciana. This first author was supported by the Aid Programme of Research and Development of Universitat Politecnica de Valencia [PAID-01-18].

[EN] Multicore optical fibers are of great interest in the optical sensing field. Their core diversity and spatial distribution enable the development of sensing mechanisms that are not possible in single-core fibers. In this paper, we study the use of the inter-core crosstalk phenomena for the implementation of a surrounding refractive index (SRI) sensor. The selective inscription of a tilted fiber Bragg grating (TFBG) intentionally increases the inter-core crosstalk between the inscribed cores and makes it sensitive to the SRI. With this technique we simplify the measurement of the SRI and improve the identification and tracking of the excited cladding modes, as compared with the analysis of the transmission spectrum of a TFBG in single-core fibers. The proposed device is also sensitive to temperature. Temperature is obtained from the crosstalk wavelength shift with a measured sensitivity of 9.75 pm/degrees C. The SRI is obtained from the measurement of the crosstalk optical power. For increasing SRIs the cladding modes gradually fade, reducing the crosstalk optical power. We observed that the higher the tilt, the higher the sensor sensitivity. For a 7 degrees TFBG the SRI sensitivity obtained is -74.2 dB/RIU from 1.31 to 1.39 and -250.8 dB/RIU from 1.39 to 1.44., This work was supported in part by the Spanish Ministry of Economy and Competitiveness under the DIMENSION TEC2017 88029-R Project and in part by the Generalitat Valenciana by PROMETEO 2017/103 research excellency award and IDI/FEDER/2018 GVA Infraestructura. The work of J. Madrigal was supported by Universitat Politecnica de Valencia scholarship PAID-01-18. The work of D. Barrera was supported by Spanish MICINN fellowship IJCI-2017-32476.