Marino Arroyo

There is broad consensus that intermediate filaments, such as keratin, play a key role in protecting cells and tissues from large deformations. However, little is known about how they fulfil this function. Here we show that epithelial cells slowly adapt to stretching through a coupling of a star-bundling transition of keratin filaments with the escape of the nucleus from its keratin cage. The bundling transition begins with a depletion of keratin filaments at tricellular junctions followed by a progressive accumulation in thick bundles that bisect cell–cell junctions. Bundling is a cooperative process that initiates in a few scattered cells and propagates to their neighbours, leading to the growth of multicellular clusters that contain a percolated network of thick keratin bundles. Bundling dynamics are slow and strongly influenced by the interaction between actin and keratin. Informed by a computational model, we provide evidence that keratin bundling generates a compressive stress on the nucleus, which is relaxed by nuclear escape from the keratin cage. The topological transitions identified here provide epithelia with a multiscale mechanism to adapt to sustained stretching.

Epithelial monolayers perform a variety of mechanical functions, which include maintaining a cohesive barrier or developing three-dimensional (3D) shapes, while undergoing stretches over a wide range of magnitudes and loading rates. To perform these functions, they rely on a hierarchical organization, which spans molecules, cytoskeletal networks, adhesion complexes, and junctional networks up to the tissue scale. While the molecular understanding and ability to manipulate cytoskeletal components within cells is rapidly increasing, how these components integrate to control tissue mechanics is far less understood, partly due to the disconnect between theoretical models of subcellular dynamics and those at a tissue scale. To fill this gap, here we propose a formalism bridging active-gel models of the actomyosin cortex and 3D vertex-like models at a tissue scale. We focus on relatively short timescales or jammed tissues, such that tissue deformation is controlled by cellular deformations rather than by topological transitions of the junctional network. We show that this unified framework recapitulates a number of seemingly disconnected epithelial time-dependent phenomenologies, including stress relaxation following stretch-unstretch maneuvers, active flattening after buckling, or nonreciprocal and nonaffine pulsatile contractions. We further analyze tissue dynamics probed by a novel experimental setup operating in a pressure-controlled ensemble. Overall, the proposed framework systematically connects subcellular cortical dynamics and tissue mechanics and ties a variety of epithelial phenomenologies to a common subcellular origin.

Engineering living materials that autonomously morph into predetermined shapes holds potential for synthetic morphogenesis and soft robotics. Harnessing cellular tissues to self-organize and generate forces offers a promising route toward this goal. However, controlling tissue mechanics to direct morphogenesis remains challenging. We introduce a strategy to program tissue-shape transformations through nematic organization of cellular forces. By controlling nematic order and topological defects, we generate tissues programmed with specific stress fields. Using a theoretical framework coupling contractile nematics with thin-sheet mechanics, we show that nematically guided active stresses can drive morphogenesis through Gaussian morphing. Experimentally, detachment of nematic tissues triggers out-of-plane deformations, generating reproducible three-dimensional shapes. Integrating contractility and nematic patterning, our approach establishes a framework for designing shape-programmable living surfaces.

The actin cytoskeleton is remarkably adaptable and multifunctional. It often organizes into nematic bundles such as contractile rings or stress fibers. However, how a uniform and isotropic actin gel self-organizes into dense nematic bundles is not fully understood. Here, using an active gel model accounting for nematic order and density variations, we identify an active patterning mechanism leading to localized dense nematic structures. Linear stability analysis and nonlinear finite element simulations establish the conditions for nematic bundle self-assembly and how active gel parameters control the architecture, orientation, connectivity, and dynamics of self-organized patterns. Finally, we substantiate with discrete network simulations the main requirements for nematic bundle formation according to our theory, namely increased active tension perpendicular to the nematic direction and generalized active forces conjugate to nematic order. Our work portrays actin gels as reconfigurable active materials with a spontaneous tendency to develop patterns of dense nematic bundles.

The study investigates the enhanced properties of Chak'o nano-clay following amine functionalization and polymeric coating, which were employed for the selective removal of pharmaceuticals, pesticides, and heavy metals from the Mantaro River water in Peru. Adsorption experiments were conducted under varying conditions, including dosages ranging from 0.5 to 2.0 g/L and contact times between 1 and 6 hours. The results demonstrated that the modified Chak'o nano-clay achieved a diclofenac removal efficiency of 92.4%, an atrazine removal efficiency of 93.0%, and a lead removal efficiency of 99.5% under optimal operational conditions. The maximum adsorption capacities of the surface-modified chak'o nano-clay were found to be 45.6 mg/g for diclofenac, 48.3 mg/g for atrazine, 120.7 mg/g for lead, and 104.3 mg/g for cadmium. Kinetic analysis indicated that the adsorption data adhered to a pseudo-second-order model, while the Langmuir isotherm provided the best fit, suggesting that the adsorption occurred on a monolayer of active sites. The reusability of chak'o nano-clay was notably high, retaining more than 85% of its adsorption capacity after five complete adsorption-desorption cycles. Post-treatment water quality met food processing standards, with reductions in turbidity, mineral content, and microbial pathogens. These findings highlight that surface-modified Chak'o nano-clay represents a promising, sustainable water purification technology capable of removing multiple contaminants, thereby ensuring the safety and quality of water used in food processing in regions impacted by water pollution.

The rapid increase in agricultural waste and global food insecurity highlights the urgent need for sustainable resource utilization methods. This study investigates mycelium-based fermentation as a solution for converting plant-based agrarian byproducts, such as sugarcane bagasse and tomato pomace, into high-protein food products. The goal is to explore how fungi can improve the nutritional profile of inedible plant waste, transforming it into digestible, nutrient-rich, and palatable protein alternatives. The fermentation process breaks down complex plant fibers into simpler compounds that the fungi can metabolize, yielding high-protein biomass suitable for human or animal consumption. The results demonstrate that this approach not only addresses protein scarcity but also promotes circular agriculture by reducing waste, minimizing greenhouse gas emissions, and fostering sustainable resource management. Moreover, the scalability of mycelium-based fermentation shows promise for industrial applications, particularly in regions with abundant agricultural residues. In conclusion, this innovative biotechnological process presents a promising approach to addressing food security challenges while promoting a sustainable global food system. However, further research is needed to optimize fermentation processes, ensure regulatory compliance, and enhance consumer acceptance.

This review discusses the potential of valorizing orange biowaste as an eco-friendly approach for environmental mitigation and resource reuse. This paper focuses on how high-value compounds, such as essential oils (limonene, citral), flavonoids, polyphenols, pectin, dietary fibers, and carotenoids, found in orange peels, pomace, and seeds, can be recovered by citrus-processing industries. The systematic review references peer-reviewed studies, government policies, and case studies from citrus-producing regions, particularly in Peru, Spain, Brazil, and the United States. It provides an overview of key waste-to-value technologies. It highlights successful local initiatives in Peru, where producer organizations and small businesses have developed extraction processes to create natural food additives and cosmetic ingredients. The experiences from international models demonstrate that biowaste valorization can be integrated within the framework of a circular economy, suggesting a potential for scaling up these practices. At the same time, there are constraints, such as technological limitations and market competition, which affect the potential use of citrus biowaste in value chains. This integration can enhance environmental sustainability, leading to a cleaner and healthier environment, while also improving socio-economic conditions. The paper concludes that effective policy-making, investments in research and development, and the implementation of a circular economy model are crucial for promoting the valorization of citrus biowaste in agro-industrial systems.

La energía solar fotovoltaica es fundamental para la transición energética global, ofreciendo una fuente limpia y sostenible. Esta revisión sistemática (2019-2025) analiza la optimización técnica, aplicaciones sectoriales y gestión energética de sistemas fotovoltaicos. Se destaca que ajustar el ángulo de inclinación y azimut, junto con sistemas de seguimiento solar, puede aumentar la eficiencia entre un 5% y 40%. La mitigación del efecto térmico mejora el rendimiento en climas cálidos. Las aplicaciones incluyen agroindustria, electrificación rural, movilidad eléctrica e industria manufacturera, donde tecnologías avanzadas como inversores multifuncionales y almacenamiento optimizan la producción y reducen costos y emisiones. Sin embargo, persisten desafíos en costos iniciales, mantenimiento y adaptación a redes eléctricas. Se recomienda enfocar futuras investigaciones en tecnologías accesibles, duraderas y modelos inclusivos para ampliar el acceso en comunidades vulnerables.

There is broad consensus that intermediate filaments play a key role in protecting cells and tissues from large deformations. However, little is known about how they fulfil this function. Here we demonstrate that epithelial cells undergo a slow adaptation to stretch that couples a star- bundling transition of keratin filaments and the escape of the nucleus from its keratin cage. The bundling transition begins with a depletion of keratin filaments at tri-cellular junctions followed by a progressive accumulation in thick bundles that bisect cell-cell junctions. Bundling is a cooperative process that initiates in a few scattered cells and propagates to their neighbours through desmosomes, leading to the growth of multicellular clusters that contain a percolated network of thick keratin bundles. Bundling dynamics are slow and strongly influenced by the interaction between actin and keratin. Informed by a computational model, we provide evidence that keratin bundling generates a compressive stress on the nucleus, which is relaxed by nuclear escape from the keratin cage. The topological transitions identified here provide epithelia with a multiscale mechanism to adapt to sustained stretch.