Transient signal generation in a self-assembled nanosystem fueled by ATP

A fundamental difference exists in the way signal generation is dealt with in natural and synthetic systems. While nature uses the transient activation of signalling pathways to regulate all cellular functions, chemists rely on sensory devices that convert the presence of an analyte into a steady output signal. The development of chemical systems that bear a closer analogy to living ones (that is, require energy for functioning, are transient in nature and operate out-of-equilibrium) requires a paradigm shift in the design of such systems. Here we report a straightforward strategy that enables transient signal generation in a self-assembled system and show that it can be used to mimic key features of natural signalling pathways, which are control over the output signal intensity and decay rate, the concentration-dependent activation of different signalling pathways and the transient downregulation of catalytic activity. Overall, the reported methodology provides temporal control over supramolecular processe

Photoswitchable catalysis by a nanozyme mediated by a lightsensitive cofactor

The activity of a gold nanoparticle-based catalyst can be reversibly up- and down-regulated by light. Light is used to switch a small molecule between cis- and trans-isomers, which inhibits the catalytic activity of the nanoparticles to different extent. The system is functional in aqueous buffer, which paves the way for integrating the system in biological networks

Investigation of Electroplastic Effect on Four Grades of Duplex Stainless Steels

Since the late 1950s, an effect of electrical current in addition to joule heating on the deformation of metals called the Electroplastic Effect (EPE) has been known. It is used nowadays in the so-called Electrically Assisted Forming (EAF) processes, but the understanding of the phenomenon is not very clear yet. It has been found that EPE increases the formability of high stacking fault energy (SFE) materials, while low SFE materials reach fracture prematurely. Since Duplex Stainless Steels (DSSs) possess a microstructure consisting of two phases with very different SFE (low SFE austenite and high SFE ferrite) and they are widely used in industry, we investigated EPE on those alloys. Tensile tests at 5 A/mm2, 10 A/mm2 and 15 A/mm2 current densities along with thermal counterparts were conducted on UNS S32101, UNS S32205, UNS S32304 and UNS S32750. The DSS grades were characterized by means of optical microscopy, X-ray diffraction and their mechanical properties (ultimate tensile strength, total elongation, uniform elongation and yield stress). An increase in uniform elongation for the electrical tests compared to the thermal counterparts as well as an increase in total elongation was found. No differences were observed on the yield stress and on the ultimate tensile strength. Un uneven distribution of the current because of the different resistivity and work hardening of the two phases has been hypothesized as the explanation for the positive effect of EPE

Microstructural and Corrosion Properties of Cold Rolled Laser Welded UNS S32750 Duplex Stainless Steel

The main goal of this work was to study the effect of plastic deformation on weldability of duplex stainless steel (DSS). It is well known that plastic deformation prior to thermal cycles can enhance secondary phase precipitation in DSS which can lead to significant change of the ferrite-austenite phase ratio. From this point of view one of the most important phase transformation in DSS is the eutectoid decomposition of ferrite. Duplex stainless steels (DSSs) are a category of stainless steels which are employed in all kinds of applications where high strength and excellent corrosion resistance are both required. This favorable combination of properties is provided by their biphasic microstructure, consisting of ferrite and austenite in approximately equal volume fractions. Nevertheless, these materials may suffer from several microstructural transformations if they undergo heat treatments, welding processes or thermal cycles. These transformations modify the balanced phase ratio, compromising the corrosion and mechanical properties of the material. In this paper, the microstructural stability as a consequence of heat history due to welding processes has been investigated for a super duplex stainless steel (SDSS) UNS S32750. During this work, the effects of laser beam welding on cold rolled UNS S32750 SDSS have been investigated. Samples have been cold rolled at different thickness reduction (\u3b5 = 9.6%, 21.1%, 29.6%, 39.4%, 49.5%, and 60.3%) and then welded using Nd:YAG laser. Optical and electronical microscopy, eddy\u2019s current tests, microhardness tests, and critical pitting temperature tests have been performed on the welded samples to analyze the microstructure, ferrite content, hardness, and corrosion resistance. Results show that laser welded joints had a strongly unbalanced microstructure, mostly consisting of ferritic phase (~60%). Ferrite content decreases with increasing distance from the middle of the joint. The heat-affected zone (HAZ) was almost undetectable and no defects or secondary phases have been observed. Both hardness and corrosion susceptibility of the joints increase. Plastic deformation had no effects on microstructure, hardness or corrosion resistance of the joints, but resulted in higher hardness of the base material. Cold rolling process instead, influences the corrosion resistance of the base material

Tribocorrosion Properties of PEO Coatings Produced on AZ91 Magnesium Alloy with Silicate- or Phosphate-Based Electrolytes

In this work, the tribocorrosion behavior of plasma electrolytic oxidation (PEO)-coated AZ91 samples was studied. In particular, two different coatings were produced and compared. One was obtained with an alkaline electrolyte containing sodium phosphate, whereas the other one was produced with an alkaline electrolyte containing sodium silicate. The coatings were characterized with SEM-EDS and XRD techniques, and after the tribocorrosion tests, the wear scars were analyzed with SEM-EDS. The tribocorrosion behavior was evaluated measuring the OCP during a pin on disk test performed in an aggressive environment. Moreover, potentiodynamic polarization and electrochemical impedance spectroscopy tests were performed, to evaluate the corrosion resistance of the different samples in the absence of wear phenomena. The behavior of all the PEO-treated specimens was compared with the one of the untreated sample. A remarkable increase in the tribocorrosion performances after the PEO treatments was observed. Moreover, the samples obtained with the electrolyte containing silicates showed higher tribocorrosion performances

Parede celular de levedura em rações para alevinos de Tilápia do Nilo.

Este estudo avaliou a suplementação de diferentes níveis de parede celular de levedura spray dried (0,0%; 0,1%; 0,2% e 0,4%), em rações para alevinos de tilápia do Nilo. Foram utilizados 120 alevinos revertidos sexualmente para macho, com peso médio inicial de 2,48 ± 0,07 g, distribuídos aleatoriamente em 20 aquários circulares com volume de 60 L (seis peixes por aquário), dotados de sistema de recirculação de água com biofiltro e aquecimento controlado. O delineamento experimental foi inteiramente casualizado, com quatro tratamentos e cinco repetições. Não houve diferença significativa para conversão alimentar, taxa de crescimento específico e taxa de eficiência protéica. Para o ganho de peso houve efeito quadrático (p<0,05), com nível ótimo estimado em 0,22% de parede celular. Pode-se concluir que a inclusão de 0,22% de parede celular de levedura proporciona melhores resultados de desempenho produtivo para alevinos de tilápia do Nilo. Termos para indexação: Saccharomyces sp., glucano, manano,bitstream/item/38744/1/BP200847.pdfDocumento on-line

Desempenho produtivo de tilápias-do-nilo alimentadas com rações contendo parte aérea de mandioca.

bitstream/item/53729/1/BP201159.pd

L’ipoteca dotale giustinianea: spunti per una comparazione diacronica

This paper investigates the institution of dotal mortgage in a diachronic perspective. It is a very ancient institution systematised and regulated on several occasions by Justinian, which was already the subject of strong criticism in the late Middle Ages. Transposed only in some of the modern European codes and then definitively repealed, the dotal mortgage seems to be comparable, in terms of its nature and function, to the institution of the judicial mortgage securing support obligations at the time of separation and divorce (art. 156 co. 5 c.c. and art. 8 co. 2 L. 898/1970)

Active Inference and Behavior Trees for Reactive Action Planning and Execution in Robotics

We propose a hybrid combination of active inference and behavior trees (BTs) for reactive action planning and execution in dynamic environments, showing how robotic tasks can be formulated as a free-energy minimization problem. The proposed approach allows to handle partially observable initial states and improves the robustness of classical BTs against unexpected contingencies while at the same time reducing the number of nodes in a tree. In this work, the general nominal behavior is specified offline through BTs, where a new type of leaf node, the prior node, is introduced to specify the desired state to be achieved rather than an action to be executed as typically done in BTs. The decision of which action to execute to reach the desired state is performed online through active inference. This results in the combination of continual online planning and hierarchical deliberation, that is an agent is able to follow a predefined offline plan while still being able to locally adapt and take autonomous decisions at runtime. The properties of our algorithm, such as convergence and robustness, are thoroughly analyzed, and the theoretical results are validated in two different mobile manipulators performing similar tasks, both in a simulated and real retail environment

ultrasonic vibration turning to increase the deposition efficiency of a silica based sol gel coating

Abstract Magnesium alloys are attracting more and more attention for producing temporary prosthetic devices thanks to their bioresorbable characteristics in human environment. However, they present a reduced corrosion resistance to body fluids, which still limits their applications to a great extent. One possible way to increase the corrosion performances is to coat the device with a suitable coating that provides a barrier to the body fluids corrosion. In this work, Ultrasonic Vibration Turning (UVT) is used to create a surface texture to the AZ31 magnesium alloy with the aim of improving the surface wettability and therefore helping the subsequent coating deposition. The obtained results showed that the surface texture induced by UVT contributed to increase the surface wettability of approximately 17% compared to the conventional turning case, regardless of the adopted cutting parameters. The UVT texture proved to improve the efficiency of the coating deposition since the thickness of the deposited sol-gel coating was increased when applied to UVT surfaces, especially at the lowest depth of cut and highest cutting speed that contributed to generate deeper dimples