Unraveling the ferroelectric switching mechanisms in ferroelectric pure and La doped HfO(2 )epitaxial thin films

Epitaxial orthorhombic phase La doped HfO2 films are promising for achieving robust ferroelectric polarization without wake-up effect. However, lowering the coercive field is crucial for achieving low-power memory devices. In this work, we have investigated the influence of the La content effect on the structural and ferroelectric properties of epitaxial HfO2 thin films. We show that while the remanent polarization is optimum for 2-5 at. % La-doped HfO2 films, the coercive field is decreased with La doping. The experimental work is supported by density functional theory (DFT) calculations which show that the polarization switching in epitaxial La:HfO2 films can be understood based on the synergetic contribution of the presence of a non-ferroelectric monoclinic phase and the La doping itself that causes a reduction of the nucleation and DW motion energy barriers for the crossing path, which makes it more probable than the non-crossing one.Financial support from the Spanish Ministry of Science and Innova- tion (MCIN/AEI/10.13039/501100011033) , through the Severo Ochoa FUNFUTURE (CEX2019-000917-S) , PID2020-112548RB-I00 and PID2019-107727RB-I00 projects, and from Generalitat de Catalunya (2021 SGR 00804) is acknowledged. We also acknowledge project TED2021-130453B-C21, funded by MCIN/AEI/10.13039/501100011033 and European Union NextGeneration EU/PRTR. This work was supported by: (i) the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding Contract UIDB/04650/2020; (ii) exploratory project 2022.01740.PDTC and (iii) the European Unions Horizon 2020 research and innovation pro- gramme under grant agreement No 958174 (M-ERA-NET3/0003/2021-NanOx4EStor) . J. P. B. S. also thanks FCT for the contract under the Institutional Call to Scientific Employment Stimulus - 2021 Call (CEE- CINST/00018/2021) . A.S. also acknowledges FCT for the PhD grant with reference 2022.13796.BD

Síntese e Caracterização Estrutural de Complexos Metálicos de Cu(II) para Modificação de Eletrodo de Carbono Vítreo por Adsorção Química

The copper complexes has been synthesized resulting in a yield of 90%. The melting point of the complex and UV-Vis spectroscopy suggested complexation with high purity. The atomic absorption spectroscopy flame determined, together with the gravimetric analysis, the stoichiometric ratio obtained between metal and ligand for the complex. The potentiometric titration proposed which active sites are related to coordination with the metal, such coordination’s sites were confirmed by infrared spectroscopy. Studies about the adsorption of chemical modifiers in the glassy carbon of the electrode surface resulting in obtaining ideal conditions for the electrode modification estimating the exact time of contact with modifier sunder ultrasound in different means of dissolution. The electrochemical properties of the electrodes howed improvements in electrochemical response to the redox couple Fe3-/4- than the unmodified electrode through organic dissolution. DOI: http://dx.doi.org/10.17807/orbital.v8i2.80

Network process of children : influence of gender and type of game during cooperative-opposition games

The children, when playing, are communicating, since this is one of the forms of disinhibition and interaction with the group in which they are inserted (Lima, 2014). Ten children, five boys (n = 5; 5.8 ± 0.4 years old of age) and five girls (n = 5; 5.6 ± 0.5 years old of age) from a elementar school were observed during classes of motor expression. These classes took place once a week for a month, lasting one hour for each session. The interactions were observed with two cameras. It was counted as an interaction when a child passed one ball to another. The results suggest that it was in the “Free Game” that there were significant diferences between the type of game, since it was found in this one that it was easier for a player to be connected with his colleagues, being later the most requested, at the moment they had to pass the ball. Between the type of game and the gender, no significant interactions were found, as children who were the ones most requested by their classmates when they had to pass the ball were not verified. However, children who were crucial to maintaining cross-pass connections were also not checked. With regard to gender, no significant differences were found because no child, both male and female, has become important in sustaining the connections between the passes and the fact that no boys and / or girls were the most requested to make the passes with the ball. Finally, among the game types, no significant differences were found, since the children did not become essential to maintain the connection of passes between colleagues, in any of the matches played. The main objective of this study is to compare the interaction between female and male children in the type of cooperative-opposition games through Social Network Analysis.info:eu-repo/semantics/publishedVersio

Spin-1/2 "bosons" with mass dimension 3/2 and fermions with mass dimension 1 cannot represent physical particle states

We delve into the first principles of quantum field theory to prove that the so-called spin-1/2 "bosons" and the fermions with mass dimension 1, including ELKO, cannot represent physical particle states with spin 1/2. Specifically, we first demonstrate that both aforementioned fields are not invariant under rotational symmetry, which implies that the particles created for these fields are not eigenstates of the spin operator in the (1/2, 0) circle plus (0, 1/2) representation of the Lorentz group, nor is it possible to construct a Hamiltonian density scalar under the rotational group from them. Furthermore, following Weinberg's approach to local causal fields, we prove that regardless of any discrete symmetry or adjoint structure, the relativistic fields in the (1/2, 0) circle plus (0, 1/2) representation satisfy the Fermi-Dirac statistics in complete agreement with the well-established spin-statistics theorem and experimental results.Peer reviewe

Dynamics Around an Asteroid Modeled as a Mass Tripole

The orbital dynamics of a spacecraft orbiting around irregular small celestial bodies is a challenging problem. Difficulties to model the gravity field of these bodies arise from the poor knowledge of the exact shape as observed from the Earth. In order to understand the complex dynamical environment in the vicinity of irregular asteroids, several studies have been conducted using simplified models. In this work, we investigate the qualitative dynamics in the vicinity of an asteroid with an arched shape using a tripole model based on the existence of three mass points linked to each other by rods with given lengths and negligible masses. We applied our results to some real systems, namely, asteroids 8567, 243 Ida and 433 Eros and also Phobos, one of the natural satellites of Mars

The dust content of high-z submillimeter galaxies revealed by Herschel

We use deep observations taken with the Photodetector Array Camera and Spectrometer (PACS), on board the Herschel satellite as part of the PACS evolutionary probe (PEP) guaranteed project along with submm ground-based observations to measure the dust mass of a sample of high-z submillimeter galaxies (SMGs). We investigate their dust content relative to their stellar and gas masses, and compare them with local star-forming galaxies. High-z SMGs are dust rich, i.e. they have higher dust-to-stellar mass ratios compared to local spiral galaxies (by a factor of 30) and also compared to local ultraluminous infrared galaxies (ULIRGs, by a factor of 6). This indicates that the large masses of gas typically hosted in SMGs have already been highly enriched with metals and dust. Indeed, for those SMGs whose gas mass is measured, we infer dust-to-gas ratios similar or higher than local spirals and ULIRGs. However, similarly to other strongly star-forming galaxies in the local Universe and at high-z, SMGs are characterized by gas metalicities lower (by a factor of a few) than local spirals, as inferred from their optical nebular lines, which are generally ascribed to infall of metal-poor gas. This is in contrast with the large dust content inferred from the far-IR and submm data. In short, the metalicity inferred from the dust mass is much higher (by more than an order of magnitude) than that inferred from the optical nebular lines. We discuss the possible explanations of this discrepancy and the possible implications for the investigation of the metalicity evolution at high-z.Comment: Accepted for publication in Astronomy & Astrophysics Letters. One reference update

DABCO-customized nanoemulsions: characterization, cell viability and genotoxicity in retinal pigmented epithelium and microglia cells

Quaternary derivatives of 1,4-diazabicyclo[2.2.2]octane (DABCO) and of quinuclidine surfactants were used to develop oil-in-water nanoemulsions with the purpose of selecting the best long-term stable nanoemulsion for the ocular administration of triamcinolone acetonide (TA). The combination of the best physicochemical properties (i.e., mean droplet size, polydispersity index, zeta potential, osmolality, viscoelastic properties, surface tension) was considered, together with the cell viability assays in ARPE-19 and HMC3 cell lines. Surfactants with cationic properties have been used to tailor the nanoemulsions surface for site-specific delivery of drugs to the ocular structure for the delivery of TA. They are tailored for the eye because they have cationic properties that interact with the anionic surface of the eye.Portuguese Science and Technology Foundation (FCT) from the Ministry of Science and Technology (MCTES), European Social Fund (FSE) of the EU, for the scholarship SFRH/BD/130555/2017 granted to A. R. Fernandes, and for the projects UIDB/04469/2020 (CEB strategic fund) and UIDB/04033/2020 (CITAB), co-funded by European Funds (PRODER/COMPETE) and FEDER, under the Partnership Agreement PT2020info:eu-repo/semantics/publishedVersio

Levels and patterns of objectively assessed physical activity and compliance with different public health guidelines in university students

ArticleBackground Physical activity (PA) is associated with health enhancement. The aim of this study was to assess: 1) levels and patterns of PA in university students by using accelerometers; and 2) the percentage of fulfilment of PA recommendations for adults, according to different public health guidelines. Methods Observational cross-sectional study (Cuenca’s Adults Study) involving 296 (206 women) healthy Spanish university students aged 18–25 years old. Participants wore the ActiGraph GT1M accelerometer for seven consecutive days. Total PA, steps and time spent in sedentary time, light, moderate, vigorous, and moderate to vigorous PA (MVPA) was assessed, and the prevalence of sufficient PA was calculated according to various public health guidelines. Results No sex differences in total PA were found. University students were more sedentary during weekend days than weekdays (p<0.05). Only 30.3% of participants accumulated 30 min/day at least five days a week of MVPA. A total of 5.4% of students met the recommendation of 150 min/week of MVPA or 75 min/week of vigorous PA, in PA bouts of at least 10 min. using the same definition, but on five or more days a week, only 0.5% students were found to meet the recommendation. In addition, only 0.5% of students met the recommendation of 30 min/day of MVPA, at least five days a week and in bouts of at least 10 min. Finally, 28.1% of the students met the recommendation of 10,000 steps/day. Conclusions Our study shows a high incidence of sedentary time in university students. The number of students meeting PA recommendations significantly differed depending on the recommendation proposed. Specific strategies to promote PA in this population are necessary as well as an agreement as to which PA guidelines should be used.Fundación para la Investigación SanitariaMinistry of Health and Consumer AffairsInstituto de Salud Carlos IIIRed de Investigación en Actividades Preventivas y de Promoción de Salu

Mono- and dicationic DABCO/Quinuclidine composed nanomaterials for the loading of steroidal drug: 32 factorial design and physicochemical characterization

Oil-in-water nanoemulsions (NEs) are considered a suitable nanotechnological approach to improve the eye-related bioavailability of lipophilic drugs. The potential of cationic NEs is prominent due to the electrostatic interaction that occurs between the positively charged droplets with the negatively charged mucins present in the tear film. This interaction offers prolonged NEs residence at the ocular surface, increasing the drug absorption. Triamcinolone acetonide (TA) is one of the first pharmacologic strategies applied as an intravitreal injection in the treatment of age-related macular degeneration (AMD). Newly synthesized quaternary derivatives of 1,4-diazabicyclo[2.2.2]octane (DABCO) and quinuclidine surfactants have been screened with the purpose to select the best compound to formulate long-term stable NEs that combine the best physicochemical properties for the loading of TA intended for ocular administration.This work was funded by the Portuguese Science and Technology Foundation (FCT) from the Ministry of Science and Technology (MCTES), European Social Fund (FSE) of EU, for the scholar ship SFRH/BD/130555/2017 granted to A. R. Fernandes, and for the projects UIDB/04469/2020 (CEB strategic fund) and UIDB/04033/2020 (CITAB), co-funded by European Funds (PRODER/COMPETE) and FEDER, under the Partnership Agreement PT2020.info:eu-repo/semantics/publishedVersio