Recent publications
The fungal green synthesis of nanoparticles (NPs) has gained great interest since it is a cost-effective and easy handling method. The process is simple because fungi secrete metabolites and proteins capable of reducing metal salts in aqueous solution, however the mechanism remains largely unknown. The aim of this study was to analyze the secretome of a Trichoderma harzianum strain during the mycobiosynthesis process of zinc and iron nanoparticles. Different profiles of proteins secreted by the fungus grown in the culture media or in the aqueous filtrate were observed through SDS‒PAGE and LC‒MS/MS analysis identifying 99 and 304 proteins, respectively. Particularly, in the aqueous filtrate proteins of metabolic processes and stress response mainly oxidoreductases, were identified. Successfully, ZnO and FeO NPs were synthesized and characterized by transmission electron microscopy, energy dispersive X-ray spectroscopy, dynamic light scattering, thermogravimetric, and FTIR analysis. FTIR revealed organic compounds in nanoparticles acting as probably capping agents. This research is the first report in which a proteomic analysis identifies multiple enzymes involved in the biogenic process of NP biosynthesis from T. harzianum, and its role is clearly demonstrated by the formation of zincite and magnetite nanoparticles.
Ammonia has attracted considerable interest as a hydrogen carrier that can help decarbonize global energy networks. Key to realizing this is the development of low temperature ammonia fuel cells for the on‐demand generation of electricity. However, the efficiency of such systems is significantly impaired by the sluggish ammonia oxidation reaction (AOR) and oxygen reduction reaction (ORR). Here, we report the design of a bifunctional Ag2Pt3TiS6 electrocatalyst that facilitates both reactions at mass activities exceeding that of commercial Pt/C. Through comprehensive density functional theory calculations, we identify that active site motifs composed of Pt and Ti atoms work cooperatively to catalyze ORR and AOR. Notably, in situ shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) experiments indicate a decreased propensity for *NOx formation and hence an increased resistance toward catalyst poisoning for AOR. Employing Ag2Pt3TiS6 as both the cathode and anode, we constructed a low temperature ammonia fuel cell with a high peak power density of 8.71 mW cm⁻² and low Pt loading of 0.45 mg cm⁻². Our findings demonstrate a pathway towards the rational design of effective electrocatalysts with multi‐element active sites that work cooperatively.
Advanced alloy production with high mechanical properties and corrosion resistance is a challenging task, sometimes technical and non-viable by conventional metallurgy process due to the need for special temperatures, inert atmospheres or requirements related to the high plastic deformation process. These alloys, crucial for aerospace, energy production and biomedical industries, demand continuous innovation in metallurgical processes and manufacturing technologies. Traditional casting methods face issues like phase segregation and high costs due to the required high temperatures for fusing refractory elements. Powder metallurgy, which presents advanced solid-state production, is an alternative route to achieve advanced alloys. Advanced secondary powder metallurgy processes can eliminate residual porosity and achieve submicron or nanoscale grain sizes, enhancing mechanical alloy properties. Secondary treatments, like hot isostatic pressing, plastic deformation and heat treatments, are necessary to optimize these alloys for high-performance applications. These processes help match or surpass the properties of traditionally manufactured alloys. The development of advanced manufacturing processes is driven by the need for materials with tailored properties for specific applications. These processes can reduce production costs and improve the properties of casting alloys, allowing for industrial-scale production that meets the severe demands of various industrial sectors.
Preventing the oxidation of oxide‐C refractories used as working linings in steelmaking vessels is crucial for maintaining their performance and extending their lifetime. This study introduces a novel methodology for evaluating and quantifying the protective effect that adhered slag can have on the oxidation of the refractory lining of steelmaking ladles. The article details the ad‐hoc methodology itself, including the technique for adhering the slag to the refractory sample and the specifically developed equipment used. The proposed experimental approach includes the evaluation of how the environmental degradation of the slag layer affects the protection it provides to the refractory against attack by environmental oxygen. Finally, the methodology's ability to provide reliable and reproducible results is shown by its application on MgO–C refractories, the most widely used type of oxide‐C products in the steelmaking industry.
Small-sized invertebrates inhabiting hard substrates in coral reefs (a.k.a. cryptofauna) contribute substantially to reef biodiversity, but their patterns of distribution and ecological controls are poorly understood. Here, we characterized the cryptofauna community and explored “bottom-up” and “top-down” controls by benthic cover and fish abundance, respectively. We sampled the cryptofauna inhabiting the reef terrace from 13 sites along 200 km in Jardines de la Reina (Cuba), a well-preserved and protected area in the Caribbean. We counted 23,959 invertebrates of 14 higher taxa, being the most abundant Copepoda (54%), Nematoda (21%), Mollusca (7%), Ostracoda (5%), Polychaeta (5%), and Amphipoda (3%). Richness, abundance, and community structure varied across the reefs without any geographical gradient of distribution. One-third of the variance occurred at site scale (~ 10 km), and half occurred at quadrat scale (~ 1 m). Algal cover promoted cryptofauna richness and abundance likely providing substrate and food, while live coral cover negatively influenced nematode abundances, potentially due to coral defenses. Relationships between cryptofauna and reef fishes were also present, with invertivores and herbivores negatively affecting cryptofauna abundance likely due to direct or indirect predation pressures. This research highlights the important roles of bottom-up and top-down controls, by algal/coral cover and fishes, respectively, on cryptofauna and in extension to coral reef biodiversity. Current threats by climate change are expected to alter these controls on cryptofauna resulting in changes to diversity, trophodynamics and energy flows of coral reefs.
Polyolefins such as polyethylenes and polypropylenes are the most‐produced plastic waste globally, yet are difficult to convert into useful products due to their unreactivity. Pyrolysis is a practical method for large‐scale treatment of mixed, contaminated plastic, allowing for their conversion into industrially‐relevant petrochemicals. Metal–organic frameworks (MOFs), despite their tremendous utility in heterogeneous catalysis, have been overlooked for polyolefin depolymerization due to their perceived thermal instabilities and inability of polyethylenes and polypropylenes to penetrate their pores. Herein, we demonstrate the viability of UiO‐66 MOFs containing coordinatively‐unsaturated zirconium nodes, as effective catalysts for pyrolysis that significantly enhances the yields of valuable liquid and gas hydrocarbons, whilst halving the amounts of residual solids produced. Reactions occur on the Lewis‐acidic UiO‐66 nodes, without the need for noble metals, and yield aliphatic product distributions distinctly different from the aromatic‐rich hydrocarbons that can be obtained from zeolite catalysis. We also demonstrate the first unambiguous characterization of polyolefin penetration into UiO‐66 pores at pyrolytic temperatures, allowing access to the abundant Zr‐oxo nodes within the MOF interior for efficient C−C cleavage. Our work highlights the potential of MOFs as highly‐designable heterogeneous catalysts for depolymerisation of plastics, which can complement conventional catalysts in reactivity.
Evaporation is a key to global water and energy cycle. It drives climate dynamics, and regulates human body temperature. It has a perennial nature rarely observed in other energy sources, including sunlight. Despite this, evaporation has hardly ever been exploited for energy harvesting. ¹ The few limited efforts to-date mainly focused on indirect approaches, via mechanical or biochemical means, yielding only minuscule amount of power. ²⁻⁴ Herein, we demonstrate scalable and continuous direct-harvesting of electricity from evaporation (evapolectrics), which leverages on wet-bulb depression to maintain robust temperature gradient (ΔT) across thermoelectric generators. The power density of 4.2 W/m ² from evapolectrics is comparable to those of indoor photovoltaics, triboelectrics, and radiative cooling power harvesting. ⁵ Our demonstration suggests a compelling development of ambient-energy harvesting technologies in powering small electronics.
Temperature‐responsive hydrogels, or thermogels, have emerged as a leading platform for sustained delivery of both small molecule drugs and macromolecular biologic therapeutics. Although thermogel properties can be modulated by varying the polymer's hydrophilic‐hydrophobic balance, molecular weight and degree of branching, varying the supramolecular donor‐acceptor interactions on the polymer remains surprisingly overlooked. Herein, to study the influence of enhanced hydrogen bonding on thermogelation, we synthesized a family of amphiphilic polymers containing urea and urethane linkages using quinuclidine as an organocatalyst. Our findings showed that the presence of strongly hydrogen bonding urea linkages significantly enhanced polymer hydration in water, in turn affecting hierarchical polymer self‐assembly and macroscopic gel properties such as sol‐gel phase transition temperature and gel stiffness. Additionally, analysis of the sustained release profiles of Aflibercept, an FDA‐approved protein biologic for anti‐angiogenic treatment, showed that urea bonds on the thermogel were able to significantly alter the drug release mechanism and kinetics compared to usage of polyurethane gels of similar composition and molecular weight. Our findings demonstrate the unrealized possibility of modulating gel properties and outcomes of sustained drug delivery through judicious variation of hydrogen bonding motifs on the polymer structure.
Este caso de estudio examina la promoción de los estudios culturales, la equidad social y la preservación del patrimonio en la educación rural colombiana. Se utilizaron técnicas cualitativas como estudio de campo, observación, entrevistas semiestructuradas y talleres para estudiar las diferentes formas de patrimonio en la comunidad de Altos de la Florida (Colombia), donde se diagnosticó que el patrimonio natural es fundamental. La primera fase consistió en el estudio y análisis del contexto inmediato de la comunidad, seguida de una segunda fase donde se realizaron talleres artísticos y recreativos para 30 niños entre 5 y 14 años, que representan el 10% de los 300 habitantes de la comunidad. Durante la tercera fase, se realizó un ejercicio previo a la exposición para comprender la definición de patrimonio de los participantes. Los resultados mostraron que los niños más pequeños se centraron en la naturaleza y la historia familiar, mientras que los niños mayores mostraron interés en la identidad comunitaria y el territorio. La exposición reveló que el patrimonio natural fue el tema más destacado, mientras que el patrimonio familiar fue el menos explorado. El estudio destaca la importancia de los métodos pedagógicos para mejorar la educación rural y propone una futura iniciativa de investigación para establecer una "Escuela del Mundo". que además contribuya a las metas de equidad social y preservación cultural, alineándose con los objetivos de la Agenda 2030
Poly ethylene-terephthalate (PET) is currently considered one of the plastics with the greatest potential for recycling, and then a good candidate in the transition towards a circular economy. However, processing and re-processing may deteriorate PET properties, since they involve high temperatures and shear stresses that together with the presence of moisture (due to the strong hydrophilic nature of PET) can provoke hydrolysis of the polymer with a corresponding loss in molecular weight. It is evident the huge importance of the drying stage in the processing of this resin. However, it has not been yet studied the influence of different techniques on the final mechanical properties of processed parts and on the processing cycle (time/costs). In this work, two drying techniques were applied: a conventional one in an oven widely used in the industry, and a novel one that uses infrared rays. The aim was to study their influence on the processing cycle, and mainly on the final mechanical properties of PET parts obtained from both virgin material and waste soda bottles. It was found that drying by infrared technology reduces drying time by 80% which implies a drastic reduction in total processing time for both virgin and recycled PET. In addition, no significant differences were found in the conventional and non-conventional mechanical properties, but differences in the propagation mode under fracture were noticeable. These were found to be due to unintentional esterification reactions induced by IR radiation in thick materials, probably due to heat concentration, that can be avoided by using thinner materials.
In this research, hydrogels based on chitosan, pectin, and salt (NaCl) were synthesized through the formation of polyelectrolyte complexes (PECs). The synthesis parameters, including pH, salinity, and polymer concentration, were varied to explore their influence. Weight and texture analysis revealed differences in hydrogel morphology. Swelling behavior studies showed hydrogels synthesized at pH 4 exhibiting higher swelling capacities. Additionally, the presence of salt affected the formation process. Thermal characterization showed a first decomposition step occurring around 180–224 °C. Morphological testing using SEM highlighted differences in pore size and distribution, notably when salt was included in the formulation (pore wall diameter without NaCl, 2.2 ± 1.1 um, with NaCl, 4.7 ± 1.2 um). Physico-chemical tests, including Zeta potential, FTIR, and XRD, provided insights into interactions within the hydrogels: hydrogen bonds and electrostatic interactions. Moreover, antibacterial tests demonstrated efficacy against Escherichia coli and Staphylococcus aureus, with varying inhibition degrees correlated with NaCl content (halo for E. coli without NaCl, 8 and 10 mm; with NaCl, 10 and 15 mm). Further assessments, including water vapor transmission rate (WVTR) and lidocaine release assays, highlighted hydrogel potential for wound dressing applications, with suitable moisture retention properties and controlled drug release capabilities. The release percentage achieved by the hydrogel with 0.15 M NaCl was higher than without salt (111.1% ± 9.5% and 31.16% ± 15.13%, respectively). Preliminary in vivo wound healing studies showed promising results. Overall, our findings emphasize the tunable properties of these hydrogels and their potential for wound dressings.
(Bi0.5Na0.5)1−xBaxTiO3 lead-free ferroelectric ceramics were synthesized via the conventional solid-state reaction method. Structural and dielectric properties were investigated as a function of the doping concentration, considering x = 0, 2, 5, 8, 10, 12, 16, and 18 at. % Ba. The structural analyses were carried out from the x-ray diffraction technique, including the Rietveld refinement method, and Raman spectroscopy. Results confirmed the formation of the perovskite structure, revealing different crystalline symmetries, depending on the Ba²⁺ concentration: the single rhombohedral ferroelectric phase (R3c) for x = 0 and 2 at. %; coexistence of both rhombohedral ferroelectric (R3c) and tetragonal antiferroelectric (P4bm) phases for x = 5 at. % Ba; the single tetragonal antiferroelectric phase (P4bm) for x = 8 at. % Ba; coexistence of two tetragonal phases (antiferroelectric P4bm and ferroelectric P4mm) for x = 10 at. % Ba; and the single tetragonal ferroelectric phase (P4mm) for x = 12, 16, and 18 at. % Ba. The characteristics of the phases’ transition, investigated from dielectric analysis, revealed the presence of two dielectric anomalies, which indeed have been associated to different phases’ transitions, one of them showing relaxor-like characteristics. The obtained results offer new insights for a better understanding on the features of the phase diagram for the studied ceramic system, according to the different observed crystalline symmetries (ferroelectric and antiferroelectric) in a very wide doping concentration. In the light of the obtained results, a new phase diagram has been proposed considering a wider compositional range than those reported in the literature.
In this report, we present the results on the physicochemical characterization of cadmium telluride quantum dots (QDs) stabilized with glutathione and prepared by optimizing the synthesis conditions. An excellent control of emissions and the composition of the nanocrystal surface for its potential application in monoclonal antibody and biomarker testing was achieved. Two samples (QDYellow, QDOrange, corresponding to their emission colors) were analyzed by dynamic light scattering (DLS), and their hydrodynamic sizes were 6.7 nm and 19.4 nm, respectively. Optical characterization by UV-vis absorbance spectroscopy showed excitonic peaks at 517 nm and 554 nm. Photoluminescence spectroscopy indicated that the samples have a maximum intensity emission at 570 and 606 nm, respectively, within the visible range from yellow to orange. Infrared spectroscopy showed vibrational modes corresponding to the functional groups OH-C-H, C-N, C=C, C-O, C-OH, and COOH, which allows for the formation of functionalized QDs for the manufacture of biomarkers. In addition, the hydrodynamic radius, zeta potential, and approximate molecular weight were determined by dynamic light scattering (DLS), electrophoretic light scattering (ELS), and static light scattering (SLS) techniques. Size dispersion and the structure of nanoparticles was obtained by Transmission Electron Microscopy (TEM) and by X-ray diffraction. In the same way, we calculated the concentration of Cd²⁺ ions expressed in mg/L by using the Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-OES). In addition to the characterization of the nanoparticles, the labeling of murine myeloid cells was carried out with both samples of quantum dots, where it was demonstrated that quantum dots can diffuse into these cells and connect mostly with the cell nucleus.
Vitrimers represent an emerging class of polymeric materials that combine the desirable characteristics of both thermoplastics and thermosets achieved through the design of dynamic covalent bonds within the polymer networks. However, these materials are prone to creep due to the inherent instability of dynamic covalent bonds. Consequently, there are pressing demands for the development of robust and stable dynamic covalent chemistries. Here, we report a catalyst‐free α‐acetyl cinnamate/acetoacetate (α‐AC/A) exchange reaction to develop vitrimers with remarkable creep resistance. Small‐molecule model studies revealed that the α‐AC/A exchange occurred at temperatures above 140 °C in bulk, whereas at 120 °C, this reaction was absent. For demonstration in the case of polymers, copolymers derived from common vinyl monomers were crosslinked with terephthalaldehyde to produce α‐AC/A vitrimers with tunable thermal and mechanical performance. All resulting α‐AC/A vitrimers exhibited high stability, especially in terms of creep resistance at 120 °C, while retaining commendable reprocessability when subjected to high temperatures. This work showcases the α‐AC/A exchange reaction as a novel and robust dynamic covalent chemistry capable of imparting both reprocessability and high stability to cross‐linked networks.
Aggregation is one of the most remarkable behaviours in the animal kingdom—a process that is usually governed by pheromones. Triatomines are blood-sucking bugs that act as vectors of Trypanosoma cruzi, the etiological agent of Chagas disease in mammals, including humans. Triatomines usually gather in roosting refuges by using aggregation pheromones of unknown chemical structure. In terms of vector control, one option to reduce triatomine–human contact is via capturing the insects into traps baited with lures based on such aggregation pheromones. As a first step towards this aim, we elucidated the aggregation pheromone in the triatomine Triatoma pallidipennis, using T. cruzi-infected and non-infected bugs. We used different extraction techniques and gas chromatography coupled to mass spectrometry for the identification. Also, two different bioassays were implemented for evaluating the attractant and arrestant activity of the pheromone. We found that T. pallidipennis produced short-chain aldehydes as attractants, and nitrogen-derived compounds as arrestants. We detected differences in the production and perception of these compounds according to whether animals were infected or not. These findings show that T. cruzi may influence triatomine chemical ecology and are promising tools for triatomine control.
Falls have a global impact, affecting people worldwide, with a notably high occurrence among the elderly. This study employs machine learning techniques to analyze falls and simulate Activities of Daily Living (ADL). The objective is to predict human falls by leveraging signals from accelerometers and gyroscopes as wearable sensors. By deriving statistical features such as mean, standard deviation, and range the authors successfully trained and assessed six machine learning models allowing them to compare solutions based on both wrist and waist data. The combination of these characteristics and sensors resulted in the Random Forest waist model achieving the most favorable metrics, with an accuracy rate of 97.22% in a 5‐s window.
Arsenic in groundwater poses serious health risks. Over the last decade, adhering to World Health Organization (WHO) directives, permissible arsenic levels in drinking water were reduced, requiring efficient, cost-effective, and user-friendly technologies. In this work, a hybrid nanocomposite membrane (HNM) with adsorbent mesoporous silica nanoparticles (MSN) covalently linked to organic electrospun nanofibers was developed. MSN were synthesised and superficially modified in order to be physically and chemically effective for both the conformation of the HNM and the adsorption of arsenic(V). Materials were structurally characterised by N2 adsorption/desorption, SEM, TEM, TGA, FTIR and evaluated for As(V) removal in synthetic and real groundwater samples at pH 8. In synthetic solutions, HNM lowers arsenic below WHO limits in less than 60 min, showing very fast adsorption kinetic during the first 15 min. The adsorption mechanism adheres to a pseudo-second-order reaction, signifying the chemical bonding of As(V) to active sites. Also, Langmuir model aligns with the adsorption isotherm, indicating surface saturation with a monolayer of arsenate species. HNM sustains capacity (>94%) over five adsorption/desorption cycles, enhancing viability for reuse. When exposed to real contaminated water, HNM achieves more than 60% adsorption within 60 min and 90% surface regeneration, an outstanding result for the treatment of real environmental samples without prior treatments. Therefore, this hybrid nanocomposite membrane offers an effective and viable alternative for the removal of arsenate ions from contaminated water. These outcomes could forward the design of new treatment devices with an effective and environmentally acceptable technology for arsenic removal.
Graphical Abstract
A top priority for the scientific community is reducing the greenhouse effect. Developing new materials for gas storage is a critical aspect, and new materials suitable for the adsorption of greenhouse gases such as carbon dioxide and methane are being investigated. Carbon Nano-Onions (CNOs) are one of the most recently discovered carbon allotropes, which can be synthesized by several methods, including submerged arc-discharge in water (SADW). Although the SADW method is well known, the properties of CNOs synthesized by this method as gas adsorbents have not yet been studied. Therefore, the aim of this work is to study these properties. For this purpose, CNOs were synthesized by SADW and characterized by different methods (XRD, TEM, Raman spectroscopy, and TGA) to determine their structural defects, size, morphology, and thermal stability. Their surface area, volume, and average pore size were also determined by nitrogen adsorption at 77 K measurement. Subsequently, their adsorption capacities of methane and carbon dioxide were obtained from adsorption/desorption isotherms and compared with other adsorbents found in the literature, with promising results. The predominant adsorption mode was also studied from isotherm models, and possible interaction mechanisms were provided.
Polyhydroxyalkanoates (PHAs) are biopolymers accumulated by a diversity of bacterial strains as carbon and energy reserve when grown under unbalanced nutritional conditions. Among the wide spectrum of applications for these biopolymers, the generation of nano and microparticles has drawn huge attention. PHA nanoparticles showed a high surface‐to‐volume ratio that makes them interesting for pharmaceutical uses. Bacteria from the Halomonas genus became interesting tools for biopolymer production in the last years, due to its metabolic plasticity that allows them to grow in a wide spectrum of compounds and salt concentrations. Halomonas titanicae KHS3 was previously isolated based on their ability to grow using aromatic hydrocarbons as the sole carbon source. In this work, the novelty lies in the evaluation of PHA accumulation by H. titanicae KHS3. Accumulation was successfully observed and thoroughly characterized on various carbon sources. Irrespective of the carbon source employed for growth, our experimental conditions consistently yielded PHB as the sole material identified. The truly intriguing aspect of this study is that PHB solutions in glacial acetic acid demonstrated exceptional suitability for electrospraying processing. This groundbreaking development led to the creation of nanoparticles with unique characteristics that hold immense promise for a wide range of applications.
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