Effect of silver on the phase transition and wettability of titanium oxide films

The effect of silver on the phase transition and microstructure of titanium oxide films grown by pulsed cathodic arc had been investigated by XRD, SEM and Raman spectroscopy. Following successive thermal annealing up to 1000 °C, microstructural analysis of annealed Ag-TiO2 films reveals that the incorporation of Ag nanoparticles strongly affects the transition temperature from the initial metastable amorphous phase to anatase and stable rutile phase. An increase of silver content into TiO2 matrix inhibits the amorphous to anatase phase transition, raising its temperature boundary and, simultaneously reduces the transition temperature to promote rutile structure at lower value of 600 °C. The results are interpreted in terms of the steric effects produced by agglomeration of Ag atoms into larger clusters following annealing which hinders diffusion of Ti and O ions for anatase formation and constrains the volume available for the anatase lattice, thus disrupting its structure to form rutile phase. The effect of silver on the optical and wetting properties of TiO2 was evaluated to demonstrate its improved photocatalytic performance

Surface Morphology Evolution of Chemical Vapor-Deposited Tungsten Films on Si(100)

Chemical vapor deposition (CVD) is used to prepare research-grade heterostructures and to produce the majority of industrially important thin films.[1] In particular, CVD tungsten films are used for many technological applications.[2,3] In CVD an external source maintains a fixed concentration of reactant molecules at a distance above the film surface.[4] Then, gas diffusion drives the molecules through the diffusion layer[2] towards the film surface. At the film interface a reaction must occur before new material is incorporated into the solid. Kinetic studies show that two growth regimes are usually present in CVD. At a low deposition temperature (low rate, regime I) the kinetics is controlled by the surface reaction, whereas at a high temperature (high rate, regime II), mass transport of reactants to, or reaction products from, the surface is the rate-controlling step.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Surface nanopatterning of metal thin films by physical vapour deposition onto surface-modified silicon nanodots

Nanostructuring of metallic and semiconductor surfaces in the sub-100 nm range is a key point in the development of future technologies. In this work we describe a simple and low-cost method for metal nanostructuring with 50 nm lateral and 6 nm vertical resolutions based on metal film deposition on a silane-derivatized nanostructured silicon master. The silane monolayer anti-sticking properties allow nanopattern transfer from the master to the deposited metal films as well as easy film detachment. The method is non-destructive, allowing the use of the derivatized master several times without damaging. Potential applications of the method are in the field of high-density data storage, heterogeneous catalysis and electrocatalysis, microanalysis (sensors and biosensors) and new optical devices.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Molding and Replication of Ceramic Surfaces with Nanoscale Resolution

The design of reproducible and more efficient nanofabrication routes has become a very active research field in recent years. In particular, the development of new methods for micro- and nanopatterning materials surfaces has attracted the attention of many researchers in industry and academia as a consequence of the growing relevance of patterned surfaces in many technological fields, ranging from optoelectronics to biotechnology. In this work we explore, discuss, and demonstrate the possibility of extending the well-known molding and replication strategy for patterning ceramic materials with nanoscale resolution. To achieve this goal we have combined physical deposition methods, molecule-thick antisticking coatings, and nanostructured substrates as master surfaces. This new perspective on an “old technology”, as molding is, provides an interesting alternative for high-resolution, direct surface-relief patterning of materials that currently requires expensive and time-consuming lithographic approaches.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The value of selected in vitro and in silico methods to predict acute oral toxicity in a regulatory context: results from the European Project ACuteTox

ACuteTox is a project within the 6th European Framework Programme which had as one of its goals to develop, optimise and prevalidate a non-animal testing strategy for predicting human acute oral toxicity. In its last 6months, a challenging exercise was conducted to assess the predictive capacity of the developed testing strategies and final identification of the most promising ones. Thirty-two chemicals were tested blind in the battery of in vitro and in silico methods selected during the first phase of the project. This paper describes the classification approaches studied: single step procedures and two step tiered testing strategies. In summary, four in vitro testing strategies were proposed as best performing in terms of predictive capacity with respect to the European acute oral toxicity classification. In addition, a heuristic testing strategy is suggested that combines the prediction results gained from the neutral red uptake assay performed in 3T3 cells, with information on neurotoxicity alerts identified by the primary rat brain aggregates test method. Octanol-water partition coefficients and in silico prediction of intestinal absorption and blood-brain barrier passage are also considered. This approach allows to reduce the number of chemicals wrongly predicted as not classified (LD(50)>2000mg/kg b.w.).Peer Reviewe

Bcr/Abl Interferes with the Fanconi Anemia/BRCA Pathway: Implications in the Chromosomal Instability of Chronic Myeloid Leukemia Cells

Chronic myeloid leukemia (CML) is a malignant clonal disorder of the hematopoietic system caused by the expression of the BCR/ABL fusion oncogene. Although it is well known that CML cells are genetically unstable, the mechanisms accounting for this genomic instability are still poorly understood. Because the Fanconi anemia (FA) pathway is believed to control several mechanisms of DNA repair, we investigated whether this pathway was disrupted in CML cells. Our data show that CML cells have a defective capacity to generate FANCD2 nuclear foci, either in dividing cells or after DNA damage. Similarly, human cord blood CD34+ cells transduced with BCR/ABL retroviral vectors showed impaired FANCD2 foci formation, whereas FANCD2 monoubiquitination in these cells was unaffected. Soon after the transduction of CD34+ cells with BCR/ABL retroviral vectors a high proportion of cells with supernumerary centrosomes was observed. Similarly, BCR/ABL induced a high proportion of chromosomal abnormalities, while mediated a cell survival advantage after exposure to DNA cross-linking agents. Significantly, both the impaired formation of FANCD2 nuclear foci, and also the predisposition of BCR/ABL cells to develop centrosomal and chromosomal aberrations were reverted by the ectopic expression of BRCA1. Taken together, our data show for the first time a disruption of the FA/BRCA pathway in BCR/ABL cells, suggesting that this defective pathway should play an important role in the genomic instability of CML by the co-occurrence of centrosomal amplification and DNA repair deficiencies

XANES observations of the inhibition and promotion of anatase and rutile phases in silver containing films

X-ray absorption near-edge structure (XANES) spectroscopy has been applied to characterize the phase evolution of Ag–TiO2 films subjected to annealing treatments up to 1000 C. Silver has been theoretically predicted as a rutile promoter in anatase powders lowering the transition temperature, however, no systematic studies on films have been reported yet. In this work, the Ti L2,3- and O K-edge in XANES spectra were used as fingerprints of the phase structure of the films. The results show that silver atoms strongly affect the transition of the initially amorphous films to the anatase structure, delaying the crystallization temperature up to 400 C and, at the same time, promoting the subsequent phase transformation from anatase to rutile at temperatures as low as 600 C. These results have been confirmed by X-Ray Diffraction (XRD) analysis as well as by High Resolution TEM images (HRTEM) of films.The authors thank the Spanish State Secretary of Research, Development and Innovation for its support through the FUNCOAT project, within the program Consolider Ingenio (ref. CSD2008-00023).Peer reviewe

Enhanced optical chirality with directional emission of Surface Plasmon Polaritons for chiral sensing applications

7 pags., 6 figs.Chirality is a crucial aspect in life sciences, where systems capable of enhancing the chiroptical properties of molecules are highly demanded. In this work, we present a numerical proof of concept of a novel approach towards chiral sensing, consisting in the measurement of chiroptical properties via the directional emission of Surface Plasmon Polaritons (SPPs) on a metasurface. Based on the enhanced differential absorption between right and left circularly polarized light upon interaction with a metasurface made of high refractive index dielectric unit cells, a polarization-dependent SPP differential emission is obtained. Furthermore, the plasmonic emission direction is entirely dependent on the polarization handedness. Using FDTD numerical methods we report Circular Dichroism signals of around − 6° for the unit cell, with threefold dissymmetry factor enhancements in places accessible to analytes. We believe that this work sets a brand-new branch in chiral sensing towards faster, real-time measurements.The authors gratefully acknowledge financial support from Spanish national project (No. PGC2018–096649-B-I). V. G. thanks the “ENSEMBLE3 - Centre of Excellence for nanophotonics, advanced materials and novel crystal growth-based technologies” project (GA No. MAB/2020/14) carried out within the International Research Agendas programme of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund and the European Union’s Horizon 2020 research and innovation programme Teaming for Excellence (GA. No. 857543) for support of this work. G. S. thanks the Ministry of education for his collaboration grant. J. G-C and P. A thank the Ministry of science and Innovation of Spain for their grants, FPI and Ramon y Cajal Fellowship (No. RYC-2016–20831), respectively

CVD of covalent compounds and high- Tc superconductors

Chemical vapor deposition at high temperatures provided the deposited atoms with the necessary surface mobility to ensure crystallinity and epitaxial growth. The use of high-temperature CVD in the deposition of high-T-c superconducting ceramics and covalent materials such as diamond (see Figure) and boron nitride is reviewed, and, for example, the methods used to maintain the tetrahedral arrangement of neighboring atoms during deposition discussed.Peer Reviewe

Soporte tridimensional para producción artificial de órganos y otras estructuras del organismo humano y método de obtención del mismo

Soporte tridimensional para producción artificial de órganos y otras estructuras del organismo humano y método de obtención del mismo. La invención se refiere a un método de obtención de un soporte tridimensional de apoyo a tareas de producción artificial de órganos y otras estructuras del organismo humano caracterizado por una geometría exterior, que se adapta a la forma de la estructura biológica original, rellena de un conjunto de semillas fractales sólidas que conforman una retícula tridimensional, que permite enfoques personalizados para adaptarse de forma óptima a las características propias del órgano o estructura del organismo objeto de producción artificial y que promociona el crecimiento de células vivas sobre el soporte tridimensional sintético obtenido.Peer reviewedUniversidad Politécnica de Madrid, Consejo Superior de Investigaciones Científicas (España)B2 Patente sin exámen previ