Chemical composition, antioxidant and anticorrosive activities of Thymus Algeriensis.

International audienceKnown therapeutic applications of medicinal plants were made of them an alternative to synthetic compounds. In this situation, the present study was designed to give more knowledge and helping to exploit the leaves of Thymus algeriensis by determining the chemical composition of its essential oil, the phenolic content of the aqueous extract and evaluate the antioxidant and anticorrosive activity. The essential oil was characterized by Geranyl acetate (80.8%) as mainly compound. The aqueous extract has exhibited a moderate antioxidant activity against free radical DPPH. On the other hand, this work describes the successful performance of T. algeriensis as an eco-friendly corrosion inhibitor for acidic media. The corrosion inhibiting effect of the extract and the essential oil of T. algeriensis (TAE & TAO) on mild steel in 0.5 M H 2 SO 4 solution was investigated by electrochemical studies in the presence of different concentrations of TAE & TAO ranging from 0.25 g/L to 2 g/L. Potentiodynamic polarization showed that TAE and TAO behaves as mixed type inhibitors. Nyquist plots show that the efficiency of inhibition increases with increasing concentration of T. algeriensis and the increased charge transfer resistance

Disentangling the role of the SnO layer on the pyro-phototronic effect in ZnO-based self-powered photodetectors

Self-powered photodetectors (PDs) have been recognized as one of the developing trends of next-generation optoelectronic devices. Herein, it is shown that by introducing a thin layer of SnO film between the Si substrate and the ZnO film, the self-powered photodetector Al/Si/SnO/ZnO/ITO exhibits a stable and uniform violet sensing ability with high photoresponsivity and fast response. The SnO layer introduces a built-in electrostatic field to highly enhance the photocurrent by over 1000%. By analyzing energy diagrams of the p-n junction, the underlying physical mechanism of the self-powered violet PDs is carefully illustrated. A high photo-responsivity (R) of 93 mA W-1 accompanied by a detectivity (D*) of 3.1 x 10(10) Jones are observed under self-driven conditions, when the device is exposed to 405 nm excitation laser wavelength, with a laser power density of 36 mW cm(-2) and at a chopper frequency of 400 Hz. The Si/SnO/ZnO/ITO device shows an enhancement of 3067% in responsivity when compared to the Al/Si/ZnO/ITO. The photodetector holds an ultra-fast response of approximate to 2 mu s, which is among the best self-powered photodetectors reported in the literature based on ZnO.This work was supported by: (i) the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding Contracts UIDB/04650/2020 and the Scientific and Technological Cooperation Program between Portugal (FCT) and Morocco (CNRST) - 2019/2020; (ii) the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 - Programa Operacional Competitividade e Internacionalizacao (POCI) with the reference project POCI-01-0145-FEDER-006941; (iii) CMEMS-UMinho Strategic Project UIDB/04436/2020 and UIDP/04436/2020; (iv) Infrastructures Micro & NanoFabs@PT, NORTE-01-0145-FEDER-022090, Portugal 2020 and (v) MPhotonBiopsy, PTDC/FIS-OTI/1259/2020. J.P.B. Silva also thanks FCT for the contract under the Institutional Call to Scientific Employment Stimulus - 2021 Call (CEECINST/00018/2021). The authors would also like to thank engineer Jose Santos for technical support at the Thin Film Laboratory

Energy storage performance of ferroelectric ZrO2 film capacitors: effect of HfO2:Al2O3 dielectric insert layer

The present work reports for the first time, the employment of ferroelectric ZrO2 films as energy storage capacitors utilized in pulsed power systems. Furthermore, the effect of insertion of a low permittivity dielectric HfO2:Al2O3 (HAO) layer, with a thickness ranging from 2 to 8 nm, on the tunability of ferroelectric and energy storage characteristics of ZrO2 films is assessed. The increase in thickness of the HAO layer gave rise to distorted ferroelectric loops with decreased polarization, coercive field, and hysteresis loss of the films. These results are correlated with the depolarization field induced by the insertion of the dielectric HAO layer. An optimum combination of high energy density of 54.3 J cm−3 and good storage efficiency of 51.3% are obtained for the ZrO2 film capacitors with 2 nm-thick HAO insert layer. These values correspond to an increase of ∼55% and ∼92%, from the respective values of pure ZrO2 film capacitors. In addition, the HAO/ZrO2 films showed a good fatigue endurance of energy storage performance over 109 electric field cycles. The energy storage density obtained from HAO(2 nm)/ZrO2 film capacitor is found to be higher than that reported for several Pb-based as well as Pb-free ferroelectric ceramic films with complex compositions. The present study demonstrates that simple binary oxides such as ZrO2 with ferroelectric behavior could be potential candidates for developing high performance energy storage capacitors.This work was supported by: (i) the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding Contracts UIDB/04650/2020 and the Scientific and Technological Cooperation Program between Portugal (FCT) and Morocco (CNRST) – 2019/2020; (ii) DST-SERB, Govt. of India through Grant No. ECR/2017/00006. C. I., R. N. and C. G. acknowledge the financial support from the Romanian Ministry of Education and Research within the project PN3– PCCF PN-III-P4-ID-PCCF2016-0047, contract no. 16/2018. The authors acknowledge the CERIC-ERIC Consortium for access to experimental facilities and financial support under proposal 20192055

SiGe layer thickness effect on the structural and optical properties of well-organized SiGe/SiO2 multilayers

In this work, we report on the production of regular (SiGe/SiO2)20 multilayer structures by conventional RF-magnetron sputtering, at 350 °C. Transmission electron microscopy, scanning transmission electron microscopy, raman spectroscopy, and x-ray reflectometry measurements revealed that annealing at a temperature of 1000 °C leads to the formation of SiGe nanocrystals between SiO2 thin layers with good multilayer stability. Reducing the nominal SiGe layer thickness (t SiGe) from 3.5-2 nm results in a transition from continuous SiGe crystalline layer (t SiGe ∼ 3.5 nm) to layers consisting of isolated nanocrystals (t SiGe ∼ 2 nm). Namely, in the latter case, the presence of SiGe nanocrystals ∼3-8 nm in size, is observed. Spectroscopic ellipsometry was applied to determine the evolution of the onset in the effective optical absorption, as well as the dielectric function, in SiGe multilayers as a function of the SiGe thickness. A clear blue-shift in the optical absorption is observed for t SiGe ∼ 2 nm multilayer, as a consequence of the presence of isolated nanocrystals. Furthermore, the observed near infrared values of n = 2.8 and k = 1.5 are lower than those of bulk SiGe compounds, suggesting the presence of electronic confinement effects in the nanocrystals. The low temperature (70 K) photoluminescence measurements performed on annealed SiGe/SiO2 nanostructures show an emission band located between 0.7-0.9 eV associated with the development of interface states between the formed nanocrystals and surrounding amorphous matrix.This work was partially funded by: (i) FEDER funds through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011; (ii) the transnational access framework of the ANNA Eu Project (Contract No. 026134-RII3) through the funding of the ANNA_TA_UC9_RP006 proposal; (iii) UID/CTM/50025/2013 and (iv) UID/FIS/04650/2013. EMFV is grateful for financial support through the FCT and POPH of the grant SFRH/ BPD/95905/2013. The authors would like also to thank engineer José Santos for technical support at the Thin Film Laboratory.info:eu-repo/semantics/publishedVersio

Three Feasibility Constraints on the Concept of Justice

The feasibility constraint on the concept of justice roughly states that a necessary (but not sufficient) condition for something to qualify as a conception of justice is that it is possible to achieve and maintain given the conditions of the human world. In this paper, I propose three alternative interpretations of this constraint that could be derived from different understandings of the Kantian formula 'ought implies can': the ability constraint, the motivational constraint and the institutional constraint. I argue that the three constraints constitute a sequence in the sense that accepting the motivational constraint presupposes that we accept the ability constraint, and to accept the institutional constraint presupposes that we accept both previous constraints. Adding the possibility of rejecting all three constraints, we get four distinct metatheoretical positions that theorists could take vis-a-vis the feasibility constraint on justice