The optical properties of transferred graphene and the dielectrics grown on it obtained by ellipsometry

Graphene layers grown by chemical vapour deposition (CVD) method and transferred from Cu-foils to the oxidized Si-substrates were investigated by spectroscopic ellipsometry (SE), Raman and X-Ray Photoelectron Spectroscopy (XPS) methods. The optical properties of transferred CVD graphene layers do not always correspond to the ones of the exfoliated graphene due to the contamination from the chemicals used in the transfer process. However, the real thickness and the mean properties of the transferred CVD graphene layers can be found using ellipsometry if a real thickness of the SiO2 layer is taken into account. The pulsed layer deposition (PLD) and atomic layer deposition (ALD) methods were used to grow dielectric layers on the transferred graphene and the obtained structures were characterized using optical methods. The approach demonstrated in this work could be useful for the characterization of various materials grown on graphene.Comment: 8 pages, 8 figures, 2 tables, presented on "Solid State Surfaces and Interfaces", November 2016 Piestany, Slovaki

A combined modelling and experimental characterisation of Chlamydomonas reinhardtii under monochromatic LED illumination

Industrial biotechnology is currently synonymous with heterotrophic processes that rely on bacterial, yeast, insect or mammalian cells to biosynthesise products of interest. Microalgae are of substantial biotechnological interest due their polyphyletic nature which grants them access to a wide array of high-value metabolites and their ability to grow under a variety of trophic strategies, including phototrophy. Despite significant process development and optimisation efforts, the full potential of these photosynthetic organisms has yet to be realised. One of the most impactful process parameters when cultivating microalgae is light. It is essential for phototrophic growth and remains highly influential on mixotrophic growth. Indoor cultivations relying on artificial light allow full control of illumination conditions. The advent of LED lights has lowered the costs and improved the flexibility of such installations. Specifically, the spectral composition of LED lights can be accurately and dynamically tailored to the needs of the culture. Spectral composition is known to exert regulatory control over the cell cycle and can affect the cell’s biochemical make up. The effects of illumination strategy on the model microalgae Chlamydomonas reinhardtii were characterised at three different levels (a) growth kinetics, (b) biochemical composition and, (c) transcriptional activity at key carbon nodes. To obtain the transcriptional data, RNA extraction protocols were compared and optimised. Additionally, a suite of candidate reference genes was validated to ensure accurate gene expression normalisation was possible in reverse transcriptase quantitative real-time polymerase chain reaction (RT-qPCR) studies. The growth kinetics and biochemical composition data obtained served as inputs for a previously published genome scale metabolic model. An algorithm was developed to approximate the default biomass composition in the model to experimental data in an effort to increase the fidelity of the simulations. The flux distributions obtained thereafter helped to describe the distinct metabolic fingerprints created under different trophic and illumination strategies

Numerical simulation and validation of ultrasonic de-icing system

This work presents the analytic and experimental research of de-icing method with piezoelectric transducer as actuators. For the reason of flight conditions like altitude, high and humidity. To meet the requirements for flight, deicing measures must be taken in consideration. There are lots of existing deicing methods, but the main problem is that the loss of power with them is very big increasing the consumption of fuel and decreasing the efficiency of the flight. With the development of piezoelectric ceramic technology, shear vibration deicing is more concerned for their low power consumption. Shear stress between surface and ice is generated by the forced vibration which is driven by piezoelectric. The device achieves the deicing purpose activating resonant frequencies of a structure using piezoelectric ceramic actuators to generate enough shear stress at the interface, between the surface and ice, to break the adhesion stress between them. In this study, we study the effect of shear stress generated for different distances between ceramic piezoelectric, and then analyze the relations of the shear stress and frequency. First, a numerical method was validated to assist the design of such systems. Numerical simulations were performed for the case of a flat plate testing the natural modes and harmonic response by the software ANSYS, which proves the feasibility to remove ice by piezoelectric ceramic actuator in theory. And then, validated experimentally. The model was then used to study important design parameters such as actuator positioning and the distance between them

Hardness and modulus of elasticity of atomic layer deposited Al2O3-ZrO2 nanolaminates and mixtures

This work was funded by the European Regional Development Fund project TK134 “Emerging orders in quantum and nanomaterials”, Estonian Research Agency project PRG4 “Emerging novel phases in strongly frustrated quantum magnets”.Atomic layer deposition was used to produce 90–105 nm thick alumina-zirconia mixtures and nanolaminate structures on soda-lime glass substrate. The resultant chemical and structural compositions of the thin films were characterized. Hardness and modulus of elasticity were determined by instrumented nanoindentation. The hardness of mixtures and nanolaminates were in the range of 11–15 GPa and moduli in the range of 140–180 GPa ZrO2 with 3.7 mol.-% Al2O3 crystallized in pure tetragonal phase and measured hardness reached about 15 GPa on glass substrate at indentation displacement of about 13 nm. Similar mechanical properties were measured in most thin films, except pure ZrO2, demonstrating insensitivity of mechanical properties to deposition receipt.ERDF TK134; Estonian Research Agency PRG4; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Violencia sexual contra el hombre: avance jurisprudencial de la Corte Interamericana de Derechos Humanos

This article examines the jurisprudence of the Inter–American Court of Human Rights on sexual violence when the victim is a man. In this sense it is highlighted the jurisprudential progress made in the case “Rodriguez Vera and others (‘Persons disappeared from the Palace of Justice’) vs. Colombia”, where a man was recognized, for the first time, as a victim of sexual violence. This article also mentions in general terms, the state of discussion on this topic in other spheres, both national and international.El presente artículo examina la jurisprudencia de la Corte Interamericana de Derechos Humanos sobre violencia sexual cuando la víctima es un hombre. En este sentido, se resalta el avance jurisprudencial realizado en el caso “Rodríguez Vera y otros (‘Desaparecidos del Palacio de Justicia’) vs. Colombia” donde, por primera vez, se reconoció a un hombre como víctima de violencia sexual. Asimismo, se hace mención de forma genérica al estado de la discusión sobre este tema en otras esferas, tanto nacionales como internacionales

Nanostructured Coating for Aluminum Alloys Used in Aerospace Applications

The authors would like to acknowledge the Estonian Ministry of Education and Research by granting the projects IUT2–24, TLTFY14054T, PSG448, PRG4, SLTFY16134T and by the EU through the European Regional Development Fund under project TK141 (2014-2020.4.01.15-00). The atomic oxygen testing was performed in the framework of the “Announcement of opportunity for atomic oxygen in the ESTEC Materials and Electrical Components Laboratory/ESA-TECQE-AO-013375),” through a collaboration with Picosun Oy. The authors also thank Dr. Elo Kibena-Põldsepp for the electrodeposition of Ag onto the anodized substrates.A thin industrial corrosion-protection nanostructured coating for the Al alloy AA2024-T3 is demonstrated. The coating is prepared in a two-step process utilizing hard anodizing as a pre-treatment, followed by sealing and coating by atomic layer deposition (ALD). In the first step, anodizing in sulfuric acid at a low temperature converts the alloy surface into a low-porosity anodic oxide. In the second step, the pores are sealed and coated by low-temperature ALD using different metal oxides. The resulting nanostructured ceramic coatings are thoroughly characterized by cross-sectioning using a focused ion beam, followed by scanning electron microscopy, transmission electron microscopy, X-ray microanalysis, and nanoindentation and are tested via linear sweep voltammetry, electrochemical impedance spectroscopy, salt spray, and energetic atomic oxygen flow. The best thin corrosion protection coating, made by anodizing at 20 V, 1 °C and sealing and coating with amorphous Al2O3/TiO2 nanolaminate, exhibits no signs of corrosion after a 1000 h ISO 9227 salt spray test and demonstrates a maximum surface hardness of 5.5 GPa. The same coating also suffers negligible damage in an atomic oxygen test, which is comparable to 1 year of exposure to space in low Earth orbit. © 2022 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.Estonian Ministry of Education and Research by granting the projects IUT2–24, TLTFY14054T, PSG448, PRG4, SLTFY16134T; ERDF TK141 (2014-2020.4.01.15-00); Institute of Solid State Physics, University of Latvia as the Center of Excellence acknowledges funding from the European Union’s Horizon 2020 Framework Programme H2020- WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2

Structure and behavior of ZrO2-graphene-ZrO2 stacks

Producción CientíficaZrO2-graphene-ZrO2 layered structures were built and their crystallinity was characterized before resistive switching measurements. Thin nanocrystalline ZrO2 dielectric films were grown by atomic layer deposition on chemical vapor deposited graphene. Graphene was transferred, prior to the growth of the ZrO2 overlayer, to the ZrO2 film pre-grown on titanium nitride. Nucleation and growth of the top ZrO2 layer was improved after growing an amorphous Al2O3 interface layer on graphene at lowered temperatures. Studies on resistive switching in such structures revealed that the exploitation of graphene interlayers could modify the operational voltage ranges and somewhat increase the ratio between high and low resistance states.Fondo Europeo de Desarrollo Regional (project TK134)Estonian Research Agency (grants PRG753 and PRG4)Ministerio de Economía, Industria y Competitividad (grant TEC2017-84321-C4-2-R

Thermal effects on TiN/Ti/HfO<inf>2</inf>/Pt memristors charge conduction

TiN/Ti/HfO2/Pt resistive switching devices have been fabricated, measured, and modeled. After programming the devices in the low resistance state, the current-voltage characteristic below the reset switching voltage was measured at different temperatures (from 90 to 350 K). A weak but complex temperature dependence was obtained for several voltage regimes. These memristors belong to a wider set known as valence change memories, whose conductance is determined by the formation of conductive filaments (CFs) linked to a high density of oxygen vacancies in a dielectric sandwiched between two metal electrodes. This usually leads to ohmic conduction in the low resistance state. However, a non-linear current dependence has been also observed in the measured devices, in addition to symmetric current-voltage curves for positive and negative biases in the 0-0.6 V voltage range. Three different thermal dependences have been considered for explaining the whole set of experimental data. Two of them are linked to ohmic filamentary conduction; the CF shows a conductivity enhancement due to thermally activated mechanisms at low temperatures; on the contrary, a CF conductivity degradation is observed at the higher temperatures. Finally, an additional slightly higher value for the non-linear current component as the temperature rises has also been taken into account. A semiempirical compact model has been implemented including these conduction mechanisms and their corresponding temperature dependences, the device has been simulated in LT-Spice and the experimental currents have been correctly reproduced.This research was supported by the projects A-TIC-117-UGR18, B-TIC-624-UGR20, and IE2017-5414 funded by the Consejería de Conocimiento, Investigación y Universidad, Junta de Andalucía (Spain), and the FEDER program. The study was also supported by the European Regional Development Fund project “Emerging Orders in Quantum and Nanomaterials” (No. TK134) and the Estonian Research Agency (PRG753). M.B.G. acknowledges the Ramón y Cajal under Grant No. RYC2020-030150-I.Peer reviewe