Open Access
Steering the synthesis of Fe3O4 nanoparticles under sonication by using a fractional factorial design
(Elsevier, 2021) Echeverría Morrás, Jesús; Moriones Jiménez, Paula; Garrido Segovia, Julián José; Ugarte Martínez, María Dolores; Cervera Gabalda, Laura María; Garayo Urabayen, Eneko; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Superparamagnetic iron oxide nanoparticles (MNPs) have the potential to act as heat sources in magnetic hyperthermia. The key parameter for this application is the specific absorption rate (SAR), which must be as large as possible in order to optimize the hyperthermia treatment. We applied a Plackett-Burman fractional factorial design to investigate the effect of total iron concentration, ammonia concentration, reaction temperature, sonication time and percentage of ethanol in the aqueous media on the properties of iron oxide MNPs. Characterization techniques included total iron content, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, High Resolution Transmission Electron Microscopy, and Dynamic Magnetization. The reaction pathway in the coprecipitation reaction depended on the initial Fe concentration. Samples synthesized from 0.220 mol L−1 Fe yielded magnetite and metastable precipitates of iron oxyhydroxides. An initial solution made up of 0.110 mol L−1 total Fe and either 0.90 or 1.20 mol L−1 NH3(aq) led to the formation of magnetite nanoparticles. Sonication of the reaction media promoted a phase transformation of metastable oxyhydroxides to crystalline magnetite, the development of crystallinity, and the increase of specific absorption rate under dynamic magnetization.
Open Access
Volatile compounds other than CO2 emitted by different microorganisms promote distinct posttranscriptionally regulated responses in plants
(Wiley, 2019) García Gómez, Pablo; Almagro Zabalza, Goizeder; Sánchez López, Ángela María; Bahaji, Abdellatif; Ameztoy del Amo, Kinia; Ricarte Bermejo, Adriana; Baslam, Marouane; López Gómez, Pedro; Morán Juez, José Fernando; Garrido Segovia, Julián José; Muñoz Pérez, Francisco José; Baroja Fernández, Edurne; Pozueta Romero, Javier; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua
A 'box-in-box' cocultivation system was used to investigate plant responses to microbial volatile compounds (VCs) and to evaluate the contributions of organic and inorganic VCs (VOCs and VICs, respectively) to these responses. Arabidopsis plants were exposed to VCs emitted by adjacent Alternaria alternata and Penicillium aurantiogriseum cultures, with and without charcoal filtration. No VOCs were detected in the headspace of growth chambers containing fungal cultures with charcoal filters. However, these growth chambers exhibited elevated CO2 and bioactive CO and NO headspace concentrations. Independently of charcoal filtration, VCs from both fungal phytopathogens promoted growth and distinct developmental changes. Plants cultured at CO2 levels observed in growth boxes containing fungal cultures were identical to those cultured at ambient CO2. Plants exposed to charcoal-filtered fungal VCs, nonfiltered VCs, or superelevated CO2 levels exhibited transcriptional changes resembling those induced by increased irradiance. Thus, in the 'box-in-box'' system, (a) fungal VICs other than CO2 and/or VOCs not detected by our analytical systems strongly influence the plants' responses to fungal VCs, (b) different microorganisms release VCs with distinct action potentials, (c) transcriptional changes in VC-exposed plants are mainly due to enhanced photosynthesis signaling, and (d) regulation of some plant responses to fungal VCs is primarily posttranscriptional.
Open Access
Hybrid xerogels: study of the sol-gel process and local structure by vibrational spectroscopy
(MDPI, 2021) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; López Ramón, María Victoria; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The properties of hybrid silica xerogels obtained by the sol-gel method are highly dependent on the precursor and the synthesis conditions. This study examines the influence of organic substituents of the precursor on the sol-gel process and determines the structure of the final materials in xerogels containing tetraethyl orthosilicate (TEOS) and alkyltriethoxysilane or chloroalkyltri-ethoxysilane at different molar percentages (RTEOS and ClRTEOS, R = methyl [M], ethyl [E], or propyl [P]). The intermolecular forces exerted by the organic moiety and the chlorine atom of the precursors were elucidated by comparing the sol-gel process between alkyl and chloroalkyl series. The microstructure of the resulting xerogels was explored in a structural theoretical study using Fourier transformed infrared spectroscopy and deconvolution methods, revealing the distribution of (SiO)4 and (SiO)6 rings in the silicon matrix of the hybrid xerogels. The results demonstrate that the alkyl chain and the chlorine atom of the precursor in these materials determines their inductive and steric effects on the sol-gel process and, therefore, their gelation times. Furthermore, the distribution of (SiO)4 and (SiO)6 rings was found to be consistent with the data from the X-ray diffraction spectra, which confirm that the local periodicity associated with four-fold rings increases with higher percentage of precursor. Both the sol-gel process and the ordered domains formed determine the final structure of these hybrid materials and, therefore, their properties and potential applications.
Open Access
Hybrid xerogels doped with Tb(III) and Eu (III) and a water soluble Pybox ligand
(2021) Cruz Quesada, Guillermo; Espinal Viguri, Maialen; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Hybrid organic-inorganic siliceous materials (ORMOSiLs) are a key focus within the nanoscience area as they combine advantages of inorganic materials without losing characteristics intrinsic of organic molecules. In the past years, our research group has designed hybrid siliceous xerogels (HSXG) with porosities and surface chemistries on demand for a range of applications, such as coatings for optic fiber sensors [1]. Although hybrid xerogels are mainly amorphous materials, recent studies by our group have demonstrated that introducing specific organic fragments on the precursors can induce selforganization during the sol-gel process to obtain a series of transparent nanostructured HSXG [2]. In the present work, a step forward is taken in the applicability of this type of HSXG by doping them with Tb(III) or Eu (III) cations and a water-soluble pybox-based antenna ligand (Pybox-EG= 2,2′-(4-(2-Ethoxyethoxy)pyridine-2,6-diyl)bis(4,5-dihydrooxazole)). Inclusion of photoluminescence will provide the materials with new properties and therefore new applications in fiber optic sensors (FOS) or in solar cells devices.
Open Access
Design of novel photoactive modified titanium silicalites and their application for venlafaxine degradation under simulated solar irradiation
(Wiley, 2024) Cruz Quesada, Guillermo; Sampaio, María J.; Espinal Viguri, Maialen; López Ramón, María Victoria; Garrido Segovia, Julián José; Silva, Cláudia G.; Faria, Joaquim L.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA18-2022
Titanium silicalites (TS) are well-known materials for their use in industrial oxidation reactions, and although they are used as photocatalysts, their activity is limited. Therefore, numerous synthetic strategies are investigated to improve their photocatalytic activity. Herein, three series of modified titanium silicalites are synthesized using three different organotriethoxysilanes at different molar percentages with the aim of modifying the structure of the zeolite, both at a porous and chemical level, to obtain materials with high photocatalytic activity. The study of their morphological, textural, chemical, and UV–vis light absorption properties through various characterization techniques has allowed the selection of the best candidates to test their photoactivity in the degradation of venlafaxine, an antidepressant drug that persists as a contaminant in wastewater and has serious neurotoxic effects. Materials synthesized using a 5% molar percentage of RTEOS and 10% of PhTEOS (Ph = phenyl) are able to degrade venlafaxine, whereas the reference material does not show any photocatalytic activity. These results lead the way to use this synthetic strategy to develop titanium silicates and optimize their photocatalytic activity in degradation reactions of different pollutants.
Open Access
Fe3O4-SiO2 mesoporous core/shell nanoparticles for magnetic field-induced ibuprofen-controlled release
(American Chemical Society, 2022-12-23) García Rodríguez, Lucía; Garayo Urabayen, Eneko; López Ortega, Alberto; Galarreta Rodríguez, Itziar; Cervera Gabalda, Laura María; Cruz Quesada, Guillermo; Cornejo Ibergallartu, Alfonso; Garrido Segovia, Julián José; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA2020; Gobierno de Navarra / Nafarroako Gobernua
Hybrid magnetic nanoparticles made up of an iron oxide, Fe3O4, core and a mesoporous SiO2 shell with high magnetization and a large surface area were proposed as an efficient drug delivery platform. The core/shell structure was synthesized by two seed-mediated growth steps combining solvothermal and sol—gel approaches and using organic molecules as a porous scaffolding template. The system presents a mean particle diameter of 30(5) nm (9 nm magnetic core diameter and 10 nm silica shell thickness) with superparamagnetic behavior, saturation magnetization of 32 emu/g, and a significant AC magnetic-field-induced heating response (SAR = 63 W/gFe3O4, measured at an amplitude of 400 Oe and a frequency of 307 kHz). Using ibuprofen as a model drug, the specific surface area (231 m2/g) of the porous structure exhibits a high molecule loading capacity (10 wt %), and controlled drug release efficiency (67%) can be achieved using the external AC magnetic field for short time periods (5 min), showing faster and higher drug desorption compared to that of similar stimulus-responsive iron oxide-based nanocarriers. In addition, it is demonstrated that the magnetic field-induced drug release shows higher efficiency compared to that of the sustained release at fixed temperatures (47 and 53% for 37 and 42 °C, respectively), considering that the maximum temperature reached during the exposure to the magnetic field is well below (31 °C). Therefore, it can be hypothesized that short periods of exposure to the oscillating field induce much greater heating within the nanoparticles than in the external solution.
Open Access
Phenyl siloxane hybrid xerogels: structure and porous texture
(Springer US, 2019) Moriones Jiménez, Paula; Echeverría Morrás, Jesús; Parra, Bernardo; Garrido Segovia, Julián José; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua
The aim of this research is to investigate the effect of phenyltriethoxysilane (PhTEOS) and tetraethoxysilane (TEOS) molar ratios as silicon precursors on the structure and porous texture of xerogels. We have prepared phenyl-silane hybrid xerogels from mixtures of PhTEOS and TEOS at pH 10 and 333 K, using ethanol as a solvent. Characterization techniques include 29Si NMR, FTIR, XRD, FE-SEM, HRTEM, TGA-DSC, helium density, and gas adsorption (N2 at 77 K and CO2 at 273 K). In order to assess the contribution of the quadrupolar moment of N2 and CO2 in the adsorption we obtained the adsorption– desorption isotherm of Ar at 87.3 K for the xerogel synthesized from 50% PhTEOS. The morphology of xerogels changed from aggregates of spherical particles for 20% PhTEOS to lamellae for samples obtained with PhTEOS percentages equal or larger that 60%. The incorporation of phenyl groups into the xerogel matrix caused an increase in the spacing bond between silicon atoms and led to an intramolecular reaction and the formation of lamellar domains. Increasing the PhTEOS molar ratio in the mixture of silicon precursors produced hybrid xerogels with lower specific surface area, pore volume and characteristic energy. The similarity between the isotherms of N2 at 77 K and Ar at 87.3 K indicates that the main retention mechanism is physisorption and that the variation in the surface chemistry with the incorporation of phenyl groups doesn’t inhibit the retention of N2.
Open Access
Determination of hazardous vapors from the thermal decomposition of organochlorinated silica xerogels with adsorptive properties
(Elsevier, 2024) Rosales Reina, María Beatriz; Cruz Quesada, Guillermo; Pujol, Pablo; Reinoso, Santiago; Elosúa Aguado, César; Arzamendi Manterola, Gurutze; López Ramón, María Victoria; Garrido Segovia, Julián José; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The incorporation of organic groups into sol-gel silica materials is known to have a noticeable impact on the properties and structure of the resulting xerogels due to the combination of the properties inherent to the organic fragments (functionality and flexibility) with the mechanical and structural stability of the inorganic matrix. However, the reduction of the inorganic content in the materials could be detrimental to their thermal stability properties, limiting the range of their potential applications. Therefore, this work aims to evaluate the thermal stability of hybrid inorganic-organic silica xerogels prepared from mixtures of tetraethoxysilane and organochlorinated triethoxysilane precursors. To this end, a series of four materials with a molar percentage of organochlorinated precursor fixed at 10%, but differing in the type of organic group (chloroalkyls varying in the alkyl-chain length and chlorophenyl), has been selected as model case study. The gases and vapors released during the thermal decomposition of the samples under N2 atmosphere have been analyzed and their components determined and quantified using a thermogravimetric analyzer coupled to a Fourier-transform infrared spectrophotometer and to a gas chromatography-mass spectrometry unit. These analyses have allowed to identify up to three different thermal events for the pyrolysis of the organochlorinated xerogel materials and to elucidate the reaction pathways associated with such processes. These mechanisms have been found to be strongly dependent on the specific nature of the organic group.
Open Access
Bioavailability of heavy metals in soils amended with sewage sludge
(Agricultural Institute of Canada, 2002) Morera Luzán, María Teresa; Echeverría Morrás, Jesús; Garrido Segovia, Julián José; Química Aplicada; Kimika Aplikatua
The recycling of sewage sludge to agricultural land results in the slow accumulation of potentially toxic heavy metals in soils. A greenhouse experiment was conducted to determine the bioavailability of Cu, Ni, Pb and Zn applied to soils in urban anaerobically stabilized sewage sludge. The soils were Lithic Haplumbrept (Lh), Calcixerollic Xerochrept (Cx1 and Cx2) and Paralithic Xerorthent (Px). Sunflower plants (Helianthus annuus L) were grown in. the soils following amendment with the sludge. The addition of sewage sludge markedly increased the average dry weight of the plants in the soils that had lower yields without sludge addition (Lh, Cx2, and Px). The acid pH of the Lh soil favoured the bioavailability of Zn from sewage sludge. The bioavailability of Cu was greater in the alkaline soils than in the acidic soil (Lh), which can be attributed to the high organic matter content of the Lh soil which complexes Cu and impairs its uptake by the plants. The concentration of metals in the plants increased with the sewage sludge dose. The effect of the soil type on the metal concentration in plants was greater that the effect of the dose.
Open Access
Henri Lenaerts: su búsqueda, su silencio
(Gobierno de Navarra, 2019) Aliende Urtasun, Ana; Garrido Segovia, Julián José; Kortadi, Edorta; Lenaerts, Henri; Masse, Judith
La exposición muestra esculturas, la mayoría de bronce, pinturas, grabados, tapices, tejidos por Paulette Garin según sus cartones, y un conjunto sobresaliente de dibujos. Todas estas obras se presentan ligadas por la visión de su comisario, Edorta Kortadi, que ve en Henri Lenaerts a un «artista trotamundos, culto, abierto, y religioso de claros acentos panteístas» y a quien se da voz también con la publicación de su autobiografía y otros escritos en el catálogo.