Forward-looking solvency contagion

Solvency contagion risk is a key channel through which systemic risk can come about. We introduce a model that accounts not only for losses transmitted after banks default, but also for losses due to the fact that creditors revalue their exposures when probabilities of default of their counterparties change. We apply the model to run a series of simplified stress tests of the UK banking system from 2008 to 2016, based on two datasets of real interbank exposures between the seven major UK banks. We show that risks due to solvency contagion decrease markedly from the peak of the crisis, to the point of becoming negligible. We also characterise the distributions of both vulnerabilities and systemic importances of individual banks, thereby tracking the evolution of risk concentration

Shedding light upon the complex net of genome size, genome composition and environment in chordates

The nucleotype theory has been advanced on the basis of studies regarding genome size and composition in various plant and animal species, i.e. the influence that genome can have on the phenotype independently of the informational content of DNA. It has also been noted that during evolution various interactions between different environmental factors and genome structural and functional parameters would have occurred. In this review, changes in genome size, transposon content, and base composition occurred during the evolution of chordates were examined. Many environmental stresses, such as temperature, can act on transposons and through these on genome size. Temperature is also one of the most important elements of natural selection able to interact both with base composition and genome size. It has been evidenced that temperature exerts a direct influence on base composition and its increase would have led to an higher content of genome GC-rich components during the evolution of chordates, in particular in endotherms. Temperature would have controlled the rate of biosynthesis in G1 phase and consequently the cell cycle duration which in turn would have interacted with genome size. The combined action of temperature, base composition, and genome size would also have been very important in controlling the metabolic rate. Finally, another important aspect of the nucleotypic effect is the influence that genome size and cell cycle duration, in correlation with environmental temperature, would have exert on embryo and larval development, very important for environmental adaptation. In conclusion, studies here reviewed to confirm the existence in chordates of a mutual influence between environment and genome non-coding components that would have played an important role in the evolution of these animals especially in environmental adaptation processes

Inorganic UV filter-based sunscreens labelled as eco-friendly threaten sea urchin populations

Although the negative effects of inorganic UV filters have been documented on several marine organisms, sunscreen products containing such filters are available in the market and proposed as eco-friendly substitutes for harmful, and already banned, organic UV filters (e.g. octinoxate and oxybenzone). In the present study, we investigated the effects of four sunscreen products, labelled by cosmetic companies as “eco-friendly”, on the early developmental stages of the sea urchin Paracentrotus lividus, a keystone species occurring in vulnerable coastal habitats. Among sunscreens tested, those containing ZnO and TiO2 or their mix caused severe impacts on sea urchin embryos. We show that inorganic UV filters were incorporated by larvae during their development and, despite the activation of defence strategies (e.g. phagocytosis by coelomocytes), generated anomalies such as skeletal malformations and tissue necrosis. Conversely, the sunscreen product containing only new-generation organic UV filters (e.g. methylene bis-benzotriazolyl tetramethyl, ethylhexyl triazone, butylphenol diethylamino hydroxybenzoyl hexyl benzoate) did not affect sea urchins, thus resulting actually eco-compatible. Our findings expand information on the impact of inorganic UV filters on marine life, corroborate the need to improve the eco-friendliness assessment of sunscreen products and warn of the risk of bioaccumulation and potential biomagnification of inorganic UV filters along the marine food chain

Chemical engineering of cationic distribution in spinel ferrite nanoparticles: the effect on the magnetic properties

A set of ∼9 nm CoFe2O4 nanoparticles substituted with Zn2+ and Ni2+ was prepared by thermal decomposition of metallic acetylacetonate precursors to correlate the effects of replacement of Co2+ with the resulting magnetic properties. Due to the distinct selectivity of these cations for the spinel ferrite crystal sites, we show that it is possible to tailor the magnetic anisotropy, saturation magnetization, and interparticle interactions of the nanoparticles during the synthesis stage. This approach unlocks new possibilities for enhancing the performance of spinel ferrite nanoparticles in specific applications. Particularly, our study shows that the replacement of Co2+ by 48% of Zn2+ ions led to an increase in saturation magnetization of approximately 40% from ∼103 A m2 kg−1 to ∼143 A m2 kg−1, whereas the addition of Ni2+ at a similar percentage led to an ∼30% decrease in saturation magnetization to 68-72 A m2 kg−1. The results of calculations based on the two-sublattice Néel model of magnetization match the experimental findings, demonstrating the model's effectiveness in the strategic design of spinel ferrite nanoparticles with targeted magnetic properties through doping/inversion degree engineering

Influence of the thermomechanical characteristics of low-density polyethylene substrates on the thermoresistive properties of graphite nanoplatelet coatings

Morphological, structural, and thermoresistive properties of films deposited on low-density polyethylene (LDPE) substrates are investigated for possible application in flexible electronics. Scanning and transmission electron microscopy analyses, and X-ray diffraction measurements show that the films consist of overlapped graphite nanoplatelets (GNP) each composed on average of 41 graphene layers. Differential scanning calorimetry and dynamic-mechanical-thermal analysis indicate that irreversible phase transitions and large variations of mechanical parameters in the polymer substrates can be avoided by limiting the temperature variations between −40 and 40◦ C. Electrical measurements performed in such temperature range reveal that the resistance of GNP films on LDPE substrates increases as a function of the temperature, unlike the behavior of graphite-based materials in which the temperature coefficient of resistance is negative. The explanation is given by the strong influence of the thermal expansion properties of the LDPE substrates on the thermo-resistive features of GNP coating films. The results show that, narrowing the temperature range from 20 to 40◦ C, the GNP on LDPE samples can work as temperature sensors having linear temperature-resistance relationship, while keeping constant the temperature and applying mechanical strains in the 0–4.2 × 10−3 range, they can operate as strain gauges with a gauge factor of about 48

Development of an FSI Environment for the Aerodynamic Performance Assessment of Flapping Wings

Insects and birds take advantage of their flexible wings to modulate the aerodynamic forces and increase their flight efficiency. A deep understanding of the aeroelastic benefits could be valuable to design Flapping Wing Micro Air Vehicles (FWMAVs) that exploit nature’s full potential. This work presents an open-source, high-fidelity, Fluid-Structure Interaction solver (FSI) to simulate flapping and deforming wings. The proposed approach uses the code CoCoNuT to couple the Computational Structural Mechanics (CSM) software Kratos Multiphysics with the Computational Fluid Dynamics (CFD) software OpenFOAM. The coupling code relies on the Interface Quasi-Newton with Inverse Jacobian method (IQNI). The CSM evaluates the wing deformation using a classic Finite Element Method with shell elements, while the CFD solver uses the deformable overset method. In the CFD solver, the deformation of the wing is interpolated onto the grid’s boundaries to accurately simulate wings with large motion and deformation. The FSI solver is tested in the case of an airfoil in heave motion and validated with experimental data. The results demonstrate the strong influence of wing deformation on its aerodynamic performanc

Network sensitivity of systemic risk

A growing body of studies on systemic risk in financial markets has emphasized the key importance of taking into consideration the complex interconnections among financial institutions. Much effort has been put into modeling the contagion dynamics of financial shocks and into assessing the resilience of specific financial markets, either using real network data, reconstruction techniques or simple toy networks. Here, we address the more general problem of how shock propagation dynamics depend on the topological details of the underlying network. To this end, we consider different realistic network topologies, all consistent with balance sheet information obtained from real data on financial institutions. In particular, we consider networks of varying density and with different block structures. In addition, we diversify in the details of the shock propagation dynamics. We confirm that the systemic risk properties of a financial network are extremely sensitive to its network features. Our results can aid in the design of regulatory policies to improve the robustness of financial markets

Microwave driven synthesis of narrow bandgap alpha-tin nanoparticles on silicon

This work proposes a microwave-based synthetic route for the preparation of tin nanospheres with a diamond-like a-phase structure on silicon. The main characteristics of the synthesized material are an extraordinarily narrow (around 50 meV) direct bandgap and an improved thermal stability (up to 200° C). Structural and compositional characterizations showed a core–shell structure comprised of an outer amorphous oxide shell and inner core containing a-phase tin domains. Microwaves turned out to be instrumental in achieving the specific nanostructures reported, due to their peculiar heating characteristics. Low pressure, low temperature and compatibility with integrated circuits manufacturing represent the most innovative features of the present synthetic process

Biphasic lithium iron oxide nanocomposites for enhancement in electromagnetic interference shielding properties

There is a great demand for efficient electromagnetic interference (EMI) shielding materials due to exponential growth in wireless telecommunication devices. These devices emit electromagnetic radiation that can disrupt electronic devices, and cause health hazards. Therefore, it is crucial to develop materials that can shield devices and humans from exposure to electromagnetic radiation. In this context, nanocomposite materials offer huge advantages due to the dual possibility of tailoring the interfaces as well as using the complementary properties of magnetic and dielectric components in the nanocomposite to enhance the EMI shielding performance. This work shows that by a careful tuning of the synthesis parameters, we can grow biphasic lithium iron oxide (ferrimagnetic α-LiFe5O8 and paramagnetic α-LiFeO2) nanocomposite with different relative fractions of the two phases. The variation of the phase fraction and the simultaneous growth of the two phases allow us to control the interfaces between the two phases as well as the physical properties of the nanocomposite, which have a direct effect on the EMI shielding performance. Detailed structural (X-ray diffraction), compositional (Raman spectroscopy), and morphological (high-resolution transmission electron microscopy) characterization is presented to understand the effect of the synthesis conditions on the EMI shielding parameters. Improved dielectric and magnetic properties together with an increased number of interfaces in the sample with nearly equal amounts of the two phases results in the best performance. This work demonstrates the significant potential of using biphasic magnetic oxide nanocomposites with controllable interfaces and physical properties for EMI shielding, which can form the base for more complex triphasic systems in the future