Thickness-dependent elastic softening of few-layer free-standing MoSe2

Few-layer van der Waals (vdW) materials have been extensively investigated in terms of their exceptional electronic, optoelectronic, optical, and thermal properties. Simultaneously, a complete evaluation of their mechanical properties remains an undeniable challenge due to the small lateral sizes of samples and the limitations of experimental tools. In particular, there is no systematic experimental study providing unambiguous evidence on whether the reduction of vdW thickness down to few layers results in elastic softening or stiffening with respect to the bulk. In this work, micro-Brillouin light scattering is employed to investigate the anisotropic elastic properties of single-crystal free-standing 2H-MoSe as a function of thickness, down to three molecular layers. The so-called elastic size effect, that is, significant and systematic elastic softening of the material with decreasing numbers of layers is reported. In addition, this approach allows for a complete mechanical examination of few-layer membranes, that is, their elasticity, residual stress, and thickness, which can be easily extended to other vdW materials. The presented results shed new light on the ongoing debate on the elastic size-effect and are relevant for performance and durability of implementation of vdW materials as resonators, optoelectronic, and thermoelectric devices

Copper nanoparticles synthesis in hybrid mesoporous thin films: Controlling oxidation state and catalytic performance through pore chemistry

The room temperature synthesis of copper (Cu) nanoparticles (NPs) supported within SiO2 mesoporous thin films (MTF) modified with either COOH or NH2 functional groups is reported. The functional groups present in the MTF surface acted as adsorption sites for Cu (II) ions, which were afterwards reduced to Cu NPs in presence of sodium borohydride at room temperature. The oxidation state of the copper NPs, corroborated by X-ray Photoelectron Spectroscopy and Electron Energy Loss Spectroscopy, was strongly dependent on the functional group present in the pores of the MTF and on the number of adsorption/reduction (A/R) cycles applied for NPs loading. Metallic Cu (0) NPs were obtained in MTFs displaying COOH groups applying 10 A/R cycles while NPs with higher oxidation state were as well present after 20 A/R cycles. For MTF functionalized with NH2 groups the copper is present as Cu (I) and Cu(II) in the NPs but no Cu (0) can be detected. The MTF-Cu(CuOx) composite materials were tested as catalysts for the reduction of 4-nitrophenol in the presence of NaBH4. Catalytic activity of composite materials depends on the oxidation state of Cu NPs, being more active those samples containing Cu (0) NPs, synthesized from COOH functionalized MTFs.Fil: Coneo Rodríguez, Rusbel. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología; ArgentinaFil: Yate, Luis. No especifíca;Fil: Coy, Emerson. Adam Mickiewicz University; PoloniaFil: Martínez Villacorta, Ángel M.. No especifíca;Fil: Bordoni, Andrea Veronica. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología; ArgentinaFil: Moya, Sergio. No especifíca;Fil: Angelome, Paula Cecilia. Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentin

Electrolysis in reduced gravitational environments: current research perspectives and future applications

Electrochemical energy conversion technologies play a crucial role in space missions, for example, in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). They are also vitally important for future long-term space travel for oxygen, fuel and chemical production, where a re-supply of resources from Earth is not possible. Here, we provide an overview of currently existing electrolytic energy conversion technologies for space applications such as proton exchange membrane (PEM) and alkaline electrolyzer systems. We discuss the governing interfacial processes in these devices influenced by reduced gravitation and provide an outlook on future applications of electrolysis systems in, e.g., in-situ resource utilization (ISRU) technologies. A perspective of computational modelling to predict the impact of the reduced gravitational environment on governing electrochemical processes is also discussed and experimental suggestions to better understand efficiency-impacting processes such as gas bubble formation and detachment in reduced gravitational environments are outlined

Strontium titanate (SrTiO3) mesoporous coatings for enhanced strontium delivery and osseointegration on bone implants

The incorporation of strontium (Sr) in titania enhances surface bioactivity and has a positive effect on pre-osteoblastic cell attachment, proliferation, and differentiation. Strontium titanate mesoporous films (SrTiMFs) with 30% pore volume and a 20% Sr molar content have been prepared by the evaporation induced self-assembly method. SrTiMFs display a large internal surface area available for exchange of Sr, which is released in cell media up to 44% within the first 8 h. SrTiMFs improve attachment of MC3T3-E1 pre-osteoblastic cells, which show larger filopodia and more elongated features than cells attached to plain mesoporous titania films (MTFs). SrTiMFs also display improved cell proliferation and differentiation rates indicating that overall Sr incorporation into mesoporous titania coatings can lead to enhanced osseointegration during the early stages of bone tissue formation.Fil: Escobar, Ane. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Muzzio, Nicolás Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Angelome, Paula Cecilia. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bordoni, Andrea Veronica. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martínez, Angel. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Bindini, Elisa. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Coy, Emerson. Adam Mickiewicz University. Nanobiomedical Centre; PoloniaFil: Andreozzi, Patrizia. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Grzelczak, Marek. Donostia International Physic Center; . Basque Foundation for Science; EspañaFil: Moya, Sergio E.. Centro de Investigación Cooperativa en Biomateriales; Españ

Antibacterial mesoporous titania films with embedded gentamicin and surface modified with bone morphogenetic protein 2 to promote osseointegration in bone implants

Novel approaches are needed to avoid bacterial infections following implant surgery. Here the use of mesoporous titania films (MTFs) for gentamicin loading and delivery and the surface functionalization of MFTs with human recombinant bone morphogenetic protein 2 (hrBMP-2) are discussed. Gentamicin is incorporated into the MTF pores by immersion of the porous materials in gentamicin solution while hrBMP-2 is adsorbed on top of the MTF. Contact angle and X-ray photoelectron spectroscopy measurements are performed to prove gentamicin loading and hrBMP-2 functionalization. An initial burst release of gentamicin takes place in physiological media followed by a prolonged release that lasts weeks. Such a release profile is highly appealing for bone implants where a high concentration of antibiotics is necessary during implant surgery while a lower antibiotic concentration is needed until tissue is regenerated. The MTFs loaded with gentamicin and functionalized with hrBMP-2 are effective against Staphylococcus aureus colonization, and the presence of hrBMP-2 enhances MC3T3-E1 preosteoblastic cell attachment, proliferation, and differentiation.Fil: Escobar, Ane. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Muzzio, Nicolás Eduardo. Centro de Investigación Cooperativa en Biomateriales; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coy, Emerson. Adam Mickiewicz University; PoloniaFil: Liu, Hui. Chinese Academy of Sciences; República de ChinaFil: Bindini, Elisa. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Andreozzi, Patrizia. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Wang, Guocheng. Chinese Academy of Sciences; República de ChinaFil: Angelome, Paula Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Delcea, Mihaela. University of Greifswald; AlemaniaFil: Grzelczak, Marek. Donostia International Physic Center; . Basque Foundation for Science; EspañaFil: Moya, Sergio E.. Centro de Investigación Cooperativa en Biomateriales; Españ

Experimental and theoretical studies of the physicochemical and mechanical properties of multi-layered TiN/SiC films: Temperature effects on the nanocomposite structure

Nanoscale multilayered TiN/SiC films are of great importance in many electronic and industrial fields. The careful control over the structure of the laminates, nanocrystalline or amorphous, is crucial for their further applicability and study. However, several limitations in their fabrication have revealed important gaps in the understanding of this system. Here, we study influence of temperature on the physico-chemical and functional properties of TiN/SiC multilayers. We will show the clear increment on hardness of the samples, while the nanocomposite structure of the layers is maintained with no increment in crystal size. We will investigate the interstitial effects and rearrangements, between the TiN/SiC phases and their role in the enhanced mechanical response. Our experiments will clearly show a change in the modulation period of the samples, pointing to interfacial reactions, diffusion of ions or crystallization of new phases. Full Investigations of the film properties were carried out using several methods of analysis: XRD, XPS, FTIR, HR-TEM and SIMS Additionally, results were combined with First Principles MD computations of TiN/SiC heterostructures