Evidence of defect-induced ferromagnetism in ZnFe2_{2}O4_{4} thin films

X-ray absorption near-edge and grazing incidence X-ray fluorescence spectroscopy are employed to investigate the electronic structure of ZnFe$_{2}$O$_{4}$ thin films. The spectroscopy techniques are used to determine the non-equilibrium cation site occupancy as a function of depth and oxygen pressure during deposition and its effects on the magnetic properties. It is found that low deposition pressures below 10$^{-3}$ mbar cause iron superoccupation of tetrahedral sites without Zn$^{2+}$ inversion, resulting in an ordered magnetic phase with high room temperature magnetic moment.Comment: Accepted for publication in Phys. Rev.

A search for new hot subdwarf stars by means of Virtual Observatory tools

Hot subdwarf stars are faint, blue objects, and are the main contributors to the far-UV excess observed in elliptical galaxies. They offer an excellent laboratory to study close and wide binary systems, and to scrutinize their interiors through asteroseismology, as some of them undergo stellar oscillations. However, their origins are still uncertain, and increasing the number of detections is crucial to undertake statistical studies. In this work, we aim at defining a strategy to find new, uncatalogued hot subdwarfs. Making use of Virtual Observatory tools we thoroughly search stellar catalogues to retrieve multi-colour photometry and astrometric information of a known sample of blue objects, including hot subdwarfs, white dwarfs, cataclysmic variables and main sequence OB stars. We define a procedure to discriminate among these spectral classes, particularly designed to obtain a hot subdwarf sample with a low contamination factor. In order to check the validity of the method, this procedure is then applied to two test sky regions: the Kepler FoV and to a test region of around (RA:225, DEC:5) deg. As a result, we obtained 38 hot subdwarf candidates, 23 of which had already a spectral classification. We have acquired spectroscopy for three other targets, and four additional ones have an available SDSS spectrum, which we used to determine their spectral type. A temperature estimate is provided for the candidates based on their spectral energy distribution, considering two-atmospheres fit for objects with clear infrared excess. Eventually, out of 30 candidates with spectral classification, 26 objects were confirmed to be hot subdwarfs, yielding a contamination factor of only 13%. The high rate of success demonstrates the validity of the proposed strategy to find new uncatalogued hot subdwarfs. An application of this method to the entire sky will be presented in a forthcoming work.Comment: 13 pages, 7 figure

New approach to determine the morphological and structural changes in the enamel as consequence of dental bleaching

Nowadays, there are a number of methods very effectives for the dental bleaching, which are typically strong oxidizing agents, as the hydrogen peroxide, applied directly to the tooth surface. After bleaching, several research studies have been carried out to evaluate the efficacy of bleaching agents on teeth, there being a great controversy concerning the techniques used and their pre-treatment requirements derived, which could alter the final results. In fact, there is a strong necessity to develop different approach to determine the real consequences of bleaching treatment by using an unchangeable and entire tooth. Herein, to evaluate the effects of 38% (p/v) hydrogen peroxide treatment onto morphological, chemical and structural features in the human enamel and dentin, environmental scanning electron microscopy, electron probe micro analyzer and X-ray diffraction techniques have been used. Although such effects have been widely investigated with several techniques, including XRD and SEM, the novelty of this study lies on the techniques and methodology used to characterize the human teeth after bleaching treatment. This approach allows carrying out the analyses without any previous pretreatment, such as powdering, dried or metal sputtering, and its study in the same tooth piece before and after bleaching, which avoids the possible intrinsic differences derived from the use of different pieces. The obtained results display that neither the structural nor the chemical features of both enamel and dentin are altered after bleaching treatment. However, the morphology of the enamel is notably altered, appearing pronounced pores which could affect to the possible bacterial colonization. These findings put an end to the controversies on the different obtained results in the literature of the bleaching effects in the enamel and set standards for future studies

Appearance of room temperature ferromagnetism in Cu-doped TiO2−δ_{2-\delta} films

In recent years there has been an intense search for room temperature ferromagnetism in doped dilute semiconductors, which have many potentially applications in spintronics and optoelectronics. We report here the unexpected observation of significant room temperature ferromagnetism in a semiconductor doped with nonmagnetic impurities, Cu-doped TiO$_2$ thin films grown by Pulsed Laser Deposition. The magnetic moment, calculated from the magnetization curves, resulted surprisingly large, about 1.5 $\mu_B$ per Cu atom. A large magnetic moment was also obtained from ab initio calculations using the supercell method for TiO$_2$ with Cu impurities, but only if an oxygen vacancy in the nearest-neighbour shell of Cu was present. This result suggests that the role of oxygen vacancies is crucial for the appearance of ferromagnetism. The calculations also predict that Cu doping favours the formation of oxygen vacancies.Comment: 4 pages, 3 figures, published in Phys. Rev. B (Rapid Comm.

Understory plant communities show resistance to drought, hurricanes, and experimental warming in a wet tropical forest

Global climate change has led to rising temperatures and to more frequent and intense climatic events, such as storms and droughts. Changes in climate and disturbance regimes can have non-additive effects on plant communities and result in complicated legacies we have yet to understand. This is especially true for tropical forests, which play a significant role in regulating global climate. We used understory vegetation data from the Tropical Responses to Altered Climate Experiment (TRACE) in Puerto Rico to evaluate how plant communities responded to climate warming and disturbance. The TRACE understory vegetation was exposed to a severe drought (2015), 2 years of experimental warming (4°C above ambient in half of the plots, 2016–2017 and 2018–2019), and two major hurricanes (Irma and María, September 2017). Woody seedlings and saplings were censused yearly from 2015 to 2019, with an additional census in 2015 after the drought ended. We evaluated disturbance-driven changes in species richness, diversity, and composition across ontogeny. We then used Bayesian predictive trait modeling to assess how species responded to disturbance and how this might influence the functional structure of the plant community. Our results show decreased seedling richness after hurricane disturbance, as well as increased sapling richness and diversity after warming. We found a shift in species composition through time for both seedlings and saplings, yet the individual effects of each disturbance were not significant. At both ontogenetic stages, we observed about twice as many species responding to experimental warming as those responding to drought and hurricanes. Predicted changes in functional structure point to disturbance-driven functional shifts toward a mixture of fast-growing and drought-tolerant species. Our findings demonstrate that the tropical forest understory community is more resistant to climatic stressors than expected, especially at the sapling stage. However, early signs of changes in species composition suggest that, in a warming climate with frequent droughts and hurricanes, plant communities might shift over time toward fast-growing or drought-tolerant species

Eficacia del tratamiento conservador en las fracturas mandibulares / Effectiveness of the conservative procedure in mandibular fractures

Se realizó un estudio en 30 pacientes con fractura mandibular, que fueron atendidos en el servicio de cirugía máxilofacial del Hospital Universitario "Abel Santamaría Cuadrado", en el periodo comprendido desde el 1ro de noviembre del 2002 hasta el 28 de febrero del 2006, con el objetivo de demostrar la eficacia del tratamiento conservador en las fracturas mandibulares según los resultados obtenidos con la reducción de la fractura, fijación y oclusión dentaria. Se plantean y analizan los resultados obtenidos, encontrando una mayor incidencia de estas fracturas de 25 a 34 años de edad, siendo las fracturas con desplazamiento y factor dentario favorable las de mayor incidencia y existiendo en el 100 % de los pacientes, al realizar el tratamiento conservador una reducción anatómica, adecuada fijación y buena oclusión. Palabras Clave: FRACTURAS MANDIBULARES/Cirugía/Terapia ABSTRACT A study of 30 patients suffering from mandibular fracture attended at the Oral Surgery Office was carried out at "Abel Santamaría Cuadrado" General hospital during November 1, 2002 to February 28, 2006. It was aimed at demonstrating the effectiveness of the findings obtained with the reduction of the fracture, fixation and dental occlusion. Findings were analyzed showing a higher incidence in 25 -34 year-old subjects, having the dislocated fractures and the dental factor a higher incidence. In 100% of cases it was observed an anatomic reduction and a proper fixation as well as a good occlusion when the conservative procedure was done. Key words: MANDIBULAR FRACTURES/Surgery/Therap

Eficacia del tratamiento conservador en las fracturas mandibulares / Effectiveness of the conservative procedure in mandibular fractures

Se realizó un estudio en 30 pacientes con fractura mandibular, que fueron atendidos en el servicio de cirugía máxilofacial del Hospital Universitario "Abel Santamaría Cuadrado", en el periodo comprendido desde el 1ro de noviembre del 2002 hasta el 28 de febrero del 2006, con el objetivo de demostrar la eficacia del tratamiento conservador en las fracturas mandibulares según los resultados obtenidos con la reducción de la fractura, fijación y oclusión dentaria. Se plantean y analizan los resultados obtenidos, encontrando una mayor incidencia de estas fracturas de 25 a 34 años de edad, siendo las fracturas con desplazamiento y factor dentario favorable las de mayor incidencia y existiendo en el 100 % de los pacientes, al realizar el tratamiento conservador una reducción anatómica, adecuada fijación y buena oclusión. Palabras Clave: FRACTURAS MANDIBULARES/Cirugía/Terapia ABSTRACT A study of 30 patients suffering from mandibular fracture attended at the Oral Surgery Office was carried out at "Abel Santamaría Cuadrado" General hospital during November 1, 2002 to February 28, 2006. It was aimed at demonstrating the effectiveness of the findings obtained with the reduction of the fracture, fixation and dental occlusion. Findings were analyzed showing a higher incidence in 25 -34 year-old subjects, having the dislocated fractures and the dental factor a higher incidence. In 100% of cases it was observed an anatomic reduction and a proper fixation as well as a good occlusion when the conservative procedure was done. Key words: MANDIBULAR FRACTURES/Surgery/Therap

Integrating pressure sensor control into semi-solid extrusion 3D printing to optimize medicine manufacturing

Semi-solid extrusion (SSE) is a three-dimensional printing (3DP) process that involves the extrusion of a gel or paste-like material via a syringe-based printhead to create the desired object. In pharmaceuticals, SSE 3DP has already been used to manufacture formulations for human clinical studies. To further support its clinical adoption, the use of a pressure sensor may provide information on the printability of the feedstock material in situ and under the exact printing conditions for quality control purposes. This study aimed to integrate a pressure sensor in an SSE pharmaceutical 3D printer for both material characterization and as a process analytical technology (PAT) to monitor the printing process. In this study, three materials of different consistency were tested (soft vaseline, gel-like mass and paste-like mass) under 12 different conditions, by changing flow rate, temperature, or nozzle diameter. The use of a pressure sensor allowed, for the first time, the characterization of rheological properties of the inks, which exhibited temperature-dependent, plastic and viscoelastic behaviours. Controlling critical material attributes and 3D printing process parameters may allow a quality by design (QbD) approach to facilitate a high-fidelity 3D printing process critical for the future of personalized medicine

The Low Redshift survey at Calar Alto (LoRCA)

The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of galaxies provides a standard ruler to measure the accelerated expansion of the Universe. To extract all available information about dark energy, it is necessary to measure a standard ruler in the local, z<0.2, universe where dark energy dominates most the energy density of the Universe. Though the volume available in the local universe is limited, it is just big enough to measure accurately the long 100 Mpc/h wave-mode of the BAO. Using cosmological N-body simulations and approximate methods based on Lagrangian perturbation theory, we construct a suite of a thousand light-cones to evaluate the precision at which one can measure the BAO standard ruler in the local universe. We find that using the most massive galaxies on the full sky (34,000 sq. deg.), i.e. a K(2MASS)<14 magnitude-limited sample, one can measure the BAO scale up to a precision of 4\% and 1.2\% using reconstruction). We also find that such a survey would help to detect the dynamics of dark energy.Therefore, we propose a 3-year long observational project, named the Low Redshift survey at Calar Alto (LoRCA), to observe spectroscopically about 200,000 galaxies in the northern sky to contribute to the construction of aforementioned galaxy sample. The suite of light-cones is made available to the public.Comment: 15 pages. Accepted in MNRAS. Please visit our website: http://lorca-survey.ft.uam.es