Artículos de revista INAMAT2 - INAMAT2 aldizkari artikuluak

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Open Access
Corrosion behavior of additively manufactured steels: a comprehensive review
(Wiley, 2025-03-21) Villabona Gorri, Eneko; Veiga Suárez, Fernando; Rivero Fuente, Pedro J.; Uralde Jiménez, Virginia; Suárez, Alfredo; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Additive manufacturing (AM) is transforming the production of steel components, offering unique advantages such as design freedom and the ability to create complex geometries. This review examines the corrosion behavior of various steel types, including austenitic stainless steels (SS), martensitic SS, duplex SS, low-alloy steels, and maraging steels, produced through AM technologies. In addition, the topic of material hybridization through AM is addressed, which allows for the optimization of the properties of the base materials. While AM often generates finer grain structures, particularly in SS, which enhances corrosion resistance, it can also lead to undesirable phases, precipitates, or defects like porosity that degrade performance. Controlling AM process parameters is crucial to achieving the desired microstructure and optimizing corrosion resistance. The review highlights current knowledge, identifies challenges, and underscores the importance of standardized testing methodologies to enable better cross-study comparisons and guide future advancements in corrosion-resistant AM steels.
Open Access
Study of spacing surface roughness parameters and proposal of a wear behaviour criterion in die-sinking EDM of cobalt-bonded tungsten carbide
(Springer, 2025-07-16) Puertas Arbizu, Ignacio; Salvide-González, Unai; Luis Pérez, Carmelo Javier; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PRO-UPNA12514
Surface roughness analysis is crucial for assessing machining quality, with most studies emphasizing amplitude parameters due to their industrial relevance. However, spacing roughness parameters, such as Sm (mean spacing of profile irregularities) and Pc (peak count), provide complementary insights into the horizontal distribution of surface features, which are often overlooked. This study investigates the effect of current intensity (I) and pulse time (ti) on Sm and Pc during the die-sinking EDM of cobalt-bonded tungsten carbide (94WC-6Co), a material widely used in wear-intensive applications due to its exceptional hardness. A multilevel design of experiments (DOE) was performed, varying I from 2 to 6 A and ti from 10 to 100 µs. Results demonstrated a strong relationship between machining conditions and both parameters, with higher current intensities increasing feature spacing (Sm) and reducing peak number (Pc). The optimal surface quality, defined by Sm = 30 µm and Pc = 337 cm⁻1, was achieved at I = 2 A and ti = 10 µs. Polynomial regression models provided predictive insights for process optimization. Scanning Electron Microscopy (SEM) analysis validated these results, revealing distinct surface morphology variations associated with the machining parameters. Finally, an attempt to define a criterion for predicting wear behaviour under the experimental conditions considered in this study will be made, where this will be based on Pc and two additional surface roughness parameters such as Rsk (skewness) and Rku (kurtosis).
Open Access
Valorisation of red mud: disclosing the potential of an abundant residue
(MDPI, 2025-02-21) Vielma, Carlos A.; Svobodova-Sedlackova, Adela; Chimenos, Josep Maria; Fernández, A. Inés; Berlanga Labari, Carlos; Rodríguez Trías, Rafael; Barreneche, Camila; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua
Red mud (RM), the primary waste product of the aluminium industry, is notable for its high concentrations of metals and rare earth elements (REE). Efforts have been made to develop extraction methods for REE recovery from RM, aiming to enhance its valorisation and reduce the European reliance on external REE sources—particularly crucial for technological advancements and the transition to renewable energy. However, these methods have only been limited to low technology readiness levels (TRLs), with no economically or technically viable processing routes yet defined to enable large-scale industrialisation within a circular economy model. This study characterised RM samples from the Seydişehir region in Türkiye using different techniques and explored the experimental process for recovering metals and REE. Moreover, the study assessed the global prospective potential of RM based on technical and economic data, as well as the sustainability of the implemented process through the life cycle assessment (LCA) tool. Results showed a total REE concentration of up to 1600 ppm, with Ce, being the most abundant (426 ± 27 ppm), followed by La, Nd, and Sc. Concentration efficiencies for La and Nd ranged between 240–300%. Sc, Y, Ce, La, and Nd have significant usage in European markets and represent prime RM targets for further prospecting. The LCA revealed that the highest global warming potential of the sequential extraction process was attributed to hydroxylamine hydrochloride and hydrogen peroxide. The findings highlight the need to explore alternative, more eco-friendly reagents to improve RM valorisation.
Open Access
Past-myopic economic agents
(Economics Bulletin, 2025-03-30) Campión Arrastia, María Jesús; Induráin Eraso, Esteban; Munárriz Iriarte, Ana; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Research in Business and Economics - INARBE; Institute for Advanced Materials and Mathematics - INAMAT2
In this paper, the idea of myopic preference and myopic topology provided by Brown and Lewis is further explored. In this sense, new definitions of myopia are introduced for finite spaces. The main contribution of the work is the inclusion of the past in the models. We have defined the notions of past-myopic preference and topology for sequence spaces and n-dimensional spaces. Adding this new dimension makes it possible to work with decision spaces where the economic agent only has information about past events and when she has to choose accordingly to it, which is in line with the reality of certain economic situations, such as voting or finances. This approach generates a wide room for future research lines related to the idea of myopia. Based on this, it would allow to study in forthcoming research past-hyperopic topologies and preferences, and to interconnect different preferences, defined on the past and future models.
Open Access
Synergic removal of Aflatoxin B1 in oily matrices by focusing on the peroxidase-like nanozymes-driven strategies: mechanisms and intermediate toxicity, nutritional impact, advances and challenges
(Elsevier, 2025-09-01) Faraji, Ali Reza; Gil Bravo, Antonio; Farahanipour, Alireza; Tehrani, Elnaz; Khoramdareh, Niloufar Bakhshi; Dashtabadi, E.; Jafari, Seyede Zeynab; Shojaei, Najmeh; Hekmatian, Zahra; Saeedi, S.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Background: oilseeds and extracted oils, as the supplier of at least 40 % of calories, dietary essential fatty acids, and food flavor, due to insufficient cultivation-harvesting techniques, processing and long-term storage in improper conditions, and lack of adequate food-safety standards and/or official consideration, are prone to contamination by AFB1. Given its irreversible adverse effects on consumer health and food/feed safety due to various factors (e.g., high chemical stability of lipophilic AFB1, transformation to other toxic derivatives, and chemical interaction with oily matrices), developing a decontamination approach from a safety/efficiency perspective is imperative. Scope and approach: this review provides the recent progress on the AFB1 detoxification from oily matrices by focusing on the peroxidase-based nanozymes technologies and enzymatic-like mechanisms of reactive species in detail for the first time. Significantly, the superiority of enzymatic-like activity in capturing/detoxifying AFB1 from oily matrices, change in nutritional quality, organoleptic profiles, and physicochemical properties of oils, and mechanism of action are highlighted by a comparison with various edible oil remediation systems (i.e., physicochemical, physical, chemical, and biological). Key findings and conclusions: The peroxidase nanozyme-based technologies could be of primary importance in the remediation of AFB1 from oily matrices due to the unique merits of nanozymes (e.g., low-cost, size/surface-dependent properties, excellent efficiency and durability/stability, recoverability, biocompatibility, many capabilities to maintain the nutritional quality, and without require to any pre-treatment). Finally, this review aimed to provide several beneficial insights regarding safety, universality, finance, ecology, rapidity, selectivity, detoxification path, and toxicity/biological nature of transformed products in peroxidase-mimicking nanozyme technologies.
Open Access
Synthesis of MOF@aluminum saline slag-based composites for CO2 capture at moderate temperatures
(Elsevier, 2025-09-01) Muñoz Alvear, Helir Joseph; Vicente, Miguel Ángel; Korili, Sophia A.; Gil Bravo, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Combining metal–organic framework (MOF) materials and aluminum-containing saline slag residues opens a promising research avenue. This approach reduces the environmental impact of aluminum production by integrating industrial waste in the development of advanced materials that adhere to circular economy principles. It also addresses some inherent stability issues observed in pure MOFs. This study is the first to propose the use of this industrial by-product as a cost-effective and environmentally friendly modulator for controlling the phase transition between MIL-96(Al) and MIL-110(Al). For the first time, novel MOFs composites (MOF@RW1*-n; n = 25, 50, 75% waste) and saline slag waste (RW1*)—a by-product of initial aluminum extraction in an acidic medium—were synthesized in situ by preparing the MOF on RW1* via hydrothermal treatment and subsequently tested as CO2 adsorbents at up to 225 ◦C and 80 kPa. The optimized RW1* content in the composite proved critical in determining the formation of specific crystalline structures (MIL-96(Al) or MIL-110(Al)), ultimately yielding hybrid materials with enhanced textural properties and thermal stability.
Open Access
The Pearcey integral in the highly oscillatory region II
(Elsevier, 2025-08-01) Ferreira González, Chelo; López García, José Luis; Pérez Sinusía, Ester; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2
We consider the Pearcey integral P(x, y) for large values of |x| and bounded values of |y|. The standard saddle point analysis is difficult to apply because the Pearcey integral is highly oscillating in this region. To overcome this problem we use the modified saddle point method introduced in López et al. (2009). A complete asymptotic analysis is possible with this method, and we derive a complete asymptotic expansion of P(x, y) for large |x|, accompanied by the exact location of the Stokes lines. There are two Stokes lines that divide the complex x−plane in two different sectors in which P(x, y) behaves differently when |x| is large. The asymptotic approximation is the sum of two asymptotic series whose terms are elementary functions of x and y. Both of them are of Poincaré type; one of them is given in terms of inverse powers of x; the other one in terms of inverse powers of x 1/2 , and it is multiplied by an exponential factor that behaves differently in the two mentioned sectors. Some numerical experiments illustrate the accuracy of the approximation.
Open Access
High-temperature superspin glass and low-temperature glassy exchange bias in passivated FeCo nanoparticles
(Elsevier, 2025-05-15) López Martín, Raúl; Lepesant, Mathieu; Lacroix, Lise-Marie; Toro, José A. de; López Ortega, Alberto; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Conventional powders, dense systems of magnetic nanoparticles, often combine intra- and inter-particle magnetically glassy properties, which may complicate their interpretation. To shed light on this matter, we have studied 9 nm FeCo particles synthesized by thermal co-decomposition of metal amides after a passivation layer around 2 nm thick has formed in ambient conditions. The saturation magnetization, 117 emu/g, is consistent with the above metallic core/ferrite shell picture. The high magnetic moment and concentration of the particles yield, via strong interparticle interactions, a remarkable room temperature superspin glass-like phase (with freezing temperature above 350 K) for such small particles, as confirmed by the de Almeida-Thouless analysis. Additionally, we detect a spin glass-like freezing at the atomic scale (within the particles). Its corresponding feature, a small hump under small fields in the temperature dependence of the magnetization, closely agrees with the onset of the exchange bias effect (∼ 60 K) measured, unlike it is customary, with repeated field-coolings. The spin-disordered nature of the core/shell interface is further proved by a strong training effect of the exchange bias field, among others. This magnetic behavior offers an indirect proof of structural interface disorder even in fully passivated metallic particles.
Open Access
Ferrihydrite surface functionalization of anatase TiO2 nanoparticles as flower-like core-shell heterostructure with enhanced visible-light-driven photocatalytic properties
(Elsevier, 2025-07-15) Gherca, Daniel; Borhan, Adrian Iulian; Herea, Daniel-Dumitru; Minuti, Anca Emanuela; Stavila, Cristina; Danceanu, Camelia Mihaela; Popescu, Dana-Georgeta; Borca, Camelia Nicoleta; Huthwelker, Thomas; Stoian, George; Chiriac, Horia; Gómez Polo, Cristina; Ababei, Gabriel; Lupu, Nicoleta; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The development of titania-based hybrid nanostructures with enhanced visible-light photocatalytic activity has been a key research area recently. The present study addresses current limitations of the TiO2 based composite photocatalyst by newly-experimental designing of flower-like multifunctional hybrid nanostructure with visible light capability through Ferrihydrite (Fh) surface TiO2 functionalization. Here, we present a versatile nanocompartimentalization process of which, core anatase TiO2 nanoparticles are emebeded into Fh lamellar shell. Physico-chemical properties related to the chemical structure and morphology of the prepared nanomaterials were comprehensively analysed using complementary analytical techniques, such as powder X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Ultra-High Resolution Transmission Electron Microscopy (UHR-TEM), X-Ray Photoelectron Spectroscopy (XPS) and soft X-Ray Absorption Spectroscopy (XAS). The conducted visible-light-driven photocatalytic water splitting tests highlights significant enhancement in the Oxygen Evolution Reaction (OER) performance for TiO2-Fh core-shell nanoheterostructure of 25.6 μmol/L of molecular oxygen after 60 min of visible light irradiation (AM1.5G), and a photocatalytic water oxidation activity rate of 341.3 μmol l-1 g-1h-1. The biocompatibility assessment of the developed core-shell structures combined with their enhanced photocatalytic water oxidation activity under visible light illumination suits them as excellent candidates for the development of sustainable environmental remediation technologies.
Open Access
Structural and functional analysis of polyethylene glycol-coated zein nanoparticles
(Elsevier, 2025-08-20) Calvopiña, Jonathan; Rivero Fuente, Pedro J.; Martínez-Ohárriz, María Cristina; Palacio, José F.; Álvarez Galindo, José Ignacio; Espuelas, Socorro; Irache, Juan M. ; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
The development of nanoparticles for drug delivery purposes is faced to a number of challenges, including the complexity of an adequate physico-chemical characterization, especially when nanoparticles are functionalized. The aim of this work was to evaluate and characterize the structure and properties of zein nanoparticles (approximately 200 nm) functionalized with polyethylene glycol (PEG 35,000) at different PEG-to-zein ratios. The interaction between PEG and zein, attributed to hydrogen bonding between the amide groups of zein and the hydroxyl groups of PEG, was evidenced by FTIR and further confirmed by 2D-COS spectroscopy. DSC and TGA thermograms demonstrated the role of PEG in improving nanoparticle thermal stability, with PEG-coated nanoparticles exhibiting higher decomposition temperatures and increased PEG content with higher PEG-to-zein ratios. SEM and AFM imaging of nanoparticle thin films confirmed that PEG decoration enhanced wettability and reduced the hydrophobicity of bare zein nanoparticles, consistent with Rose Bengal test results. Additionally, AFM analysis of nanoparticle distribution in a mucin thin film demonstrated that PEG coating improved nanoparticle dispersibility within the mucin matrix, in line with previous studies describing the increased diffusivity and mucus-permeation properties of nanoparticles coated with hydrophilic polymers. In summary, this study highlights the importance of an in-depth analysis of the physicochemical characteristics of nanoparticles, providing valuable structural insights that facilitate optimization and the selection of the most suitable compositions for preclinical development.
Open Access
Low-cost Titania-Hydroxyapatite (TiHAp) nanocomposites were synthesized for removal of methylene blue under solar and UV irradiation
(Elsevier, 2025-07-01) Latifi, Souhayla; Saoiabi, Sanaa ; Alanazi, Mohammed M. ; Boukra, Omar ; Krime, Anas ; El Hammari, Larbi; Azzaoui, Khalil; Hammouti, Belkheir; Hanbali, Ghadir; Jodeh, Shehdeh; Saoiabi, Ahmad ; Sabbahi, Rachid ; Algarra González, Manuel; Abidi, Noureddine ; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Water pollution from industrial dyes like methylene blue (MB) poses significant environmental and health risks due to their toxicity and persistence. In this study, we synthesized a novel titania-hydroxyapatite (TiHAp) nanocomposite via a low-cost, scalable sol-gel method to address these challenges. The composite was comprehensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Photocatalytic degradation of MB under both solar and UV irradiation was evaluated using kinetic (pseudo-first-order and pseudo-second-order) and isotherm (Langmuir and Freundlich) models, demonstrating hydroxyapatite's key role in enhancing adsorption and facilitating effective interactions with the catalyst. Under optimized conditions, the TiHAp nanocomposite achieved 96.58 % degradation of MB at an initial concentration of 120 mg/L and retained over 95 % activity after five reuse cycles. These results illustrate that the synergistic combination of TiO₂'s photocatalytic activity and HAp's adsorptive capacity produces a highly effective composite for degrading organic pollutants. The study underscores the potential of TiHAp nanocomposites as sustainable materials for wastewater treatment applications, while future work will explore their performance against a broader range of contaminants under realistic environmental conditions.
Open Access
Duplex treatments prepared by HiPIMS and sol-gel on biodegradable ZK60 magnesium alloy for biomedical applications
(Elsevier, 2025-09-01) Claver Alba, Adrián; Quintana, Iban; Fernández, Iván; Santiago, José A.; Díaz-Rodríguez, Pablo; Panizo-Laiz, Miguel; Zalakain Iriazabal, Iñaki; Urroz Unzueta, José Carlos; García Lorente, José Antonio; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua
The utilization of magnesium-based biomaterials in biomedical applications has grown considerably in recent years due to their favourable biocompatibility, biodegradability, and mechanical properties that closely resemble those of bones. However, the use of Mg-based alloys in aggressive environments, such as human bodily fluids, is hindered by their susceptibility to rapid corrosion, which compromises their mechanical properties. This can lead to infections in the body due to uncontrolled corrosion. In this study, a novel approach was employed to enhance the corrosion resistance of biodegradable ZK60 magnesium alloy and achieve optimal surface properties that can potentially enhance its antibacterial performance, hardness, and toughness. This approach involved the application of duplex treatments consisting of TiN doped with Cu coatings deposited via high power impulse magnetron sputtering (HiPIMS) followed by a Sol-gel top layer. The study systematically investigated the surface properties (wettability, roughness, and morphology), hardness, toughness and adhesion of the coatings to the substrate. To assess the corrosion resistance, mass change and hydrogen evolution of the samples, they were immersed in Hanks Balanced Salts Solution. Electrochemical tests were conducted to estimate the corrosion behavior of the samples. The in-vitro corrosion tests results demonstrated that the duplex treatments enhanced the corrosion resistance of the uncoated magnesium alloy samples. The duplex treatments exhibited suitable properties, including high corrosion resistance, hardness, toughness and adequate values of wettability and porosity-roughness. Therefore, they can be considered a promising option for use in biodegradable magnesium implants.
Open Access
Low temperature chemical looping combustion of pyrolysis gases in a fixed bed reactor
(Elsevier, 2025-08-01) Gracia Monforte, César; Maldonado-Martín, Francisco; Atienza Martínez, María; Ábrego, Javier; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
This study presents an experimental investigation into the feasibility of oxidizing biomass pyrolysis gases at relatively low temperatures using a chemical looping combustion (CLC) approach. The application of this alternative method would enable the capture of carbon from the pyrolysis gas stream, which is currently released into the atmosphere in most pyrolysis systems, as high-purity CO2. In a fixed bed reactor, the reduction behavior of three different Cu-based oxygen carriers (OC) - pure CuO pellets, carulite and Al2O3-supported CuO - was evaluated to determine whether pyrolysis gases could be completely oxidized to CO2 and H2O within a temperature range of 600–650 ◦C and at weight hourly space velocities (WHSV) of 0.06–0.10 h− 1 . Both CuO and carulite exhibited significant amounts of unconverted pyrolysis gases even during the initial stages of the reduction experiments. In contrast, Al2O3-supported CuO emerged as the most effective material, facilitating the complete oxidation of pyrolysis gases over extended reaction times. For this oxygen carrier, a decline in the combustion efficiency was only observed at very high (90 %) reduction conversions. Reduction/oxidation cycles for this most promising material were successfully demonstrated, with the oxygen carrier showing no signs of activity loss after 10 cycles. However, carbon deposition was detected under several experimental conditions, which could potentially reduce the carbon capture efficiency of the process.
Open Access
Enhancement of sol-gel coatings for photoprotection of rosé wines
(MDPI, 2025-02-15) Moriones, Jennifer; Osés Martínez de Zúñiga, Javier; Amézqueta, Pablo; Palacio, José F.; Fernández de Ara, Jonathan; Almandoz Sánchez, Eluxka; Ciencias; Zientziak; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
Exposure to short-wavelength light, including UV-A and blue light, can degrade high-value products like rosé wine, which are usually packaged in colourless bottles. This study investigates the optimisation of sol¿gel coatings enhanced with UV-absorbing additives (Tinuvin 479 and semaSORB 20109) to provide photoprotection for rosé wines. Coatings with varying additive concentrations (0.5%, 0.75%, 1%, and 1.5%) were applied to glass substrates via spin coating and cured with UV light. Then, optical and mechanical characterisation was performed. The 1.5% concentration semaSORB 20109 bilayer coating demonstrated improved photoprotective properties without compromising colour properties, leading to successful application on glass bottles by spray coating. Accelerated degradation tests confirmed that the optimised coating effectively protected against photodegradation, as indicated by the stability of polyphenol levels and colour parameters in rosé wines. The results suggest that these coatings could be a suitable option for commercial-scale applications, enhancing the light resistance of colourless-bottled products.
Open Access
Effect of annealing on the mechanical properties of composites of PLA mixed with Mg and with HA
(MDPI, 2025-04-28) Sánchez González, Carmen; Pérez Jiménez, Aurora Fernanda; Malvè, Mauro; Díaz Jiménez, Cristina; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
Polylactic acid (PLA) is a bioresorbable and biocompatible material and is a promising alternative to the current materials used for permanent implants as it has osteosynthesis properties. However, this material has some drawbacks due to its low mechanical and thermal resistance after 3D printing. Extensive research has been conducted to improve the properties of this material, for example, with the addition of other compounds, such as magnesium (Mg) or Hydroxyapatite (HA). These reinforced materials have been shown to reduce the internal stress of the matrix of PLA, improving the thermal, optical and structural properties of the material, even though the performance achieved is lower than needed to be implanted. In addition, although it is known that the addition of Mg or HA affects the mechanical performance of the material, mechanical properties have not been studied in the literature. Thus, the aim of this study is to research the effect of thermal post-processing based on annealing of composites made of PLA with Mg and PLA with HA, manufactured by fused filament fabrication, with the goal of finding an improvement in the mechanical properties of these materials. As a result, different designs of annealing processes have been studied with different reinforced materials and their mechanical properties have been compared, studying axial traction and compression, radial compression as well as flexibility, among others. The comparative results achieved show the relevance of the design of the annealing process for the improvement of the mechanical properties of these materials.
Open Access
Exploring the complex interplay of anisotropies in magnetosomes of magnetotactic bacteria
(American Chemical Society, 2025-04-14) Gandía Aguado, David; Marcano, Lourdes; Gandarias, Lucía; Gubieda, Alicia G.; García-Prieto, Ana; Fernández Barquín, Luis; Espeso, José Ignacio; Martín Jefremovas, E.; Orue, Iñaki; Abad Díaz de Cerio, Ana; Fernández-Gubieda, María Luisa; Alonso Masa, Javier; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Magnetotactic bacteria (MTB) are at the forefront of interest for biophysics applications, especially in cancer treatment. Magnetosomes biomineralized by these bacteria are high-quality magnetic nanoparticles that form chains inside the MTB through a highly reproducible, naturally driven process. In particular, Magnetovibrio blakemorei and Magnetospirillum gryphiswaldense MTB exhibit distinct magnetosome morphologies: truncated hexa-octahedral and cuboctahedral shapes, respectively. Despite having identical compositions (magnetite, Fe3O4) and dimensions within a similar size range, their effective uniaxial anisotropies significantly differ at room temperature, with M. blakemorei exhibiting ∼25 kJ/m3 and M. gryphiswaldense ∼ 11 kJ/m3. This prominent anisotropy variance provides a unique opportunity to explore the role of magnetic anisotropy contributions in the magnetic responses of these magnetite-based nanoparticles. This study systematically investigates these responses by examining static magnetization as a function of temperature (M vs T, 5 mT) and magnetic field (M vs μ0H, up to 1 T). Above the Verwey transition temperature (∼110 K), the effective anisotropy is dominated by the shape anisotropy contribution, notably increasing the coercivity for M. blakemorei by up to twofold compared to M. gryphiswaldense. However, below this temperature, the effective uniaxial anisotropy rapidly increases in a nonmonotonic way, significantly changing the magnetic behavior. Computational simulations using a dynamic Stoner–Wohlfarth model provide insights into these phenomena, enabling careful interpretation of experimental data. According to our simulations, below the Verwey temperature, a uniaxial magnetocrystalline contribution progressively emerges, peaking around 22–24 kJ/m3 at 5 K. Our study reveals the complex evolution of magnetocrystalline contributions, which dominate the magnetic response of magnetosomes below the Verwey temperature. This demonstrates the profound impact of anisotropic properties on the magnetic behaviors and applications of magnetite-based nanoparticles and highlights the exceptional utility of magnetosomes as ideal model systems for studying the complex interplay of anisotropies in magnetite-based nanoparticles.
Open Access
Ni-Mo2C/y-Al2O3 catalysts for syngas production in pyrolysis-dry reforming of plastics - the effect of amine nature on catalyst performance
(Elsevier, 2025-05-29) Pawelczyk, Ewelina; Frackiewicz, Izabela; Gil Bravo, Antonio; Karczewski, Jakub; Maciejewski, Michał E.; Dymerski, Tomasz; Gebicki, Jacek; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Pyrolysis combined with dry reforming (PCDR) is eco-friendly technology for plastic waste management, allowing for sustainable production of syngas. Design of suitable catalysts with high performance and stability is crucial for its industrialization. In this work, Ni-Mo2C/γ-Al2O3 catalysts were synthesized using organic–inorganic precursors. Three types of amines (hexylamine – aliphatic linear, cyclohexylamine – aliphatic cyclic, aniline – aromatic) were used as carbon source in the precursor preparation to investigate their effect on catalyst physicochemical properties and its catalytic performance. Catalytic performance of the obtained catalysts was examined in PCDR of model waste plastic mixture. It was revealed that catalytic activity of catalysts prepared with aliphatic amines was higher compared to aromatic aniline, amine commonly used for carbide synthesis. The differences in catalyst properties, which affected their catalytic activity were characterized using N2-adsorption at −196 °C, XRD, H2-TPR, SEM, TG/DTG and CO2-adsorption methods. A correlation was observed between amine molecule complexity and Mo2C crystallite size, significantly affecting hydrogen generation. The less complex the amine, the smaller the crystallite and the increased hydrogen production. Moreover, the use of aliphatic amines resulted in the stronger Ni-support interactions, the increased number of more favorable, larger mesopores as well as the presence of the metallic Mo phase and the lack of unbound carbon in contrast to the catalyst obtained using aniline. The catalyst synthesized using hexylamine increased H2 yield by more than tenfold, syngas yield by more than threefold, and the H2/CO ratio by fivefold, which offers an opportunity for future industrialization of PCDR.
Open Access
UV-photoelectron spectroscopy and MS-CASPT2/CASSCF study of the thermolysis of azidoethyl-methyl sulfide: Characterization and mechanism of the formation of S-methyl-N-sulfenylethanimine
(American Institute of Physics (AIP), 2025-05-16) Algarra González, Manuel; Labat, Stephane; Rodríguez-Borges, José Enrique; Pino-González, María Soledad; Sotiropoulos, Jean Marc; Soto, Juan; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The thermal decomposition of azidoethyl methyl sulfide was studied by real-time UV-photoelectron spectroscopy (UV-PES) at temperatures ranging from 773 to 1023 K. Different ionization energies were obtained using density functional theory calculations to assign UV-PES spectra. The complete active space self-consistent field and multistate second-order perturbation methods were used to predict the formation of different species present in the thermal decomposition process. N2 and S-methyl-N-sulfenylethanimine are generated at 773 K. The first step of the reaction is the dissociation of the molecule into nitrene and nitrogen. The spin state (singlet or triplet) of nitrene formed in the first step of the reaction is temperature-dependent. At low temperatures (T ≤ 650 K), both states are formed with almost the same probability; in contrast, at high temperatures (T ≤ 1000 K), singlet nitrene is the majority intermediate. From this singlet nitrene, three stable reaction products were detected in the experiments: an imine derivative, a four-member cyclic derivative, and a sulfenyl derivative.
Open Access
Metal-free nanostructured-carbon inks for a sustainable fabrication of zinc/air batteries: from ORR activity to a simple prototype
(Wiley, 2024-08-14) Santos, Florencio; Lorca, Sebastián; González-Martínez, Juan F.; Urbina Yeregui, Antonio; Álvarez-Sánchez, Miguel A. ; González-Domínguez, José M.; García-Bordejé, Enrique; Ansón-Casaos, Alejandro; Benito, Ana M.; Maser, Wolfgang K.; Fernández Romero, Antonio J.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Zinc/air batteries are convenient energy storage devices for both small and massive applications. While future perspectives indicate the need for low-cost components and sustainable fabrication processes, the battery performance is in part controlled by the kinetics of the oxygen reduction reaction (ORR), which typically involves transition metals as catalysts. In this context, we prepare a series of metal-free water-based carbon inks, which are tested for their catalytic performance, once deposited on a gas-diffusion substrate, in the air cathode of a simple battery prototype. The inks contain a variety of well-defined carbon nanomaterials and additives, exhibiting different physicochemical properties that critically influence the interaction with the gas diffusion hydrophobic substrate. The intrinsic ORR catalytic activity of the ink material is also analyzed on a glassy carbon electrode by the rotating ring-disc electrode (RRDE) method and specific capacitance measurements. The discharge capacity on our zinc/air battery prototype correlates well with the intrinsic catalytic activity in the RRDE. However, only the activity in the RRDE does not actually assure the performance on the commercial cathode of the prototype, since other chemical compatibility issues play a role. Thus, we highlight the importance of catalyst testing, not only on the RRDE but also under realistic device conditions.
Open Access
Compact wideband groove gap waveguide bandpass filters manufactured with 3D printing and CNC milling techniques
(MDPI, 2023-07-07) Máximo-Gutierrez, Clara; Hinojosa, Juan; Abad, José; Urbina Yeregui, Antonio; Álvarez-Melcon, Alejandro; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Zientziak
This paper presents for the first time a compact wideband bandpass filter in groove gap waveguide (GGW) technology. The structure is obtained by including metallic pins along the central part of the GGW bottom plate according to an n-order Chebyshev stepped impedance synthesis method. The bandpass response is achieved by combining the high-pass characteristic of the GGW and the low-pass behavior of the metallic pins, which act as impedance inverters. This simple structure together with the rigorous design technique allows for a reduction in the manufacturing complexity for the realization of high-performance filters. These capabilities are verified by designing a fifth-order GGW Chebyshev bandpass filter with a bandwidth BW = 3.7 GHz and return loss RL = 20 dB in the frequency range of the WR-75 standard, and by implementing it using computer numerical control (CNC) machining and three-dimensional (3D) printing techniques. Three prototypes have been manufactured: one using a computer numerical control (CNC) milling machine and two others by means of a stereolithography-based 3D printer and a photopolymer resin. One of the two resin-based prototypes has been metallized from a silver vacuum thermal evaporation deposition technique, while for the other a spray coating system has been used. The three prototypes have shown a good agreement between the measured and simulated S-parameters, with insertion losses better than IL = 1.2 dB. Reduced size and high-performance frequency responses with respect to other GGW bandpass filters were obtained. These wideband GGW filter prototypes could have a great potential for future emerging satellite communications systems.