[en] Water confined at the nanoscale has been the focus of numerous experimental and theoretical investigations in recent years, y yet there is no consensus on such basic properties et as diffusion and the nature of hydrogen bonding (HB) under confinement. Unraveling these properties is important to understand fluid flow and transport at the nanoscale, and to shed light on the solvation of biomolecules. Here we report on a first principle, computational study focusing on water confined between prototypical non polar substrate, i.e. , single wall carbon nanotubes and graphene sheets, 1 to 2.5 nm apart. The results of our molecular dynamics simulations show the presence of a thin, interfacial liquid layer (∼ 5 Angstroms) whose microscopic structure and thickness are independent of the distance between confining layers. The prop properties of the hydrogen bonded network are very similar to those of the bulk outside the interfacial region, even in the case of strong confinement , confinement. Our findings indicate that the perturbation induced by the presence of confining media is extremely local in liquid water, and we propose that many of the effects attributed to novel phases under confinement are determined by subtle electronic structure rearrangements occurring at the interface with the confining medium

[en] The thermal behavior of sodium heated steam generators is studied based on boiling curves and the concept of thermal stability. A simple model of an evaporator is investigated by two successive methods: the evolution of steady-states when sodium inlet temperature is varied is calculated by the continuation method; then, transients are calculated from an initial to a final state by the dynamic computer code SICLE to confirm the preceding results. (author)

[en] Nanowires made of materials with non-centrosymmetric crystal structures are expected to be ideal building blocks for self-powered nanodevices due to their piezoelectric properties, yet a controversial explanation of the effective operational mechanisms and size effects still delays their real exploitation. To solve this controversy, we propose a methodology based on DFT calculations of the response of nanostructures to external deformations that allows us to distinguish between the different (bulk and surface) contributions: we apply this scheme to evaluate the piezoelectric properties of ZnO [0001] nanowires, with a diameter up to 2.3 nm. Our results reveal that, while surface and confinement effects are negligible, effective strain energies, and thus the nanowire mechanical response, are dependent on size. Our unified approach allows for a proper definition of piezoelectric coefficients for nanostructures, and explains in a rigorous way the reason why nanowires are found to be more sensitive to mechanical deformation than the corresponding bulk material. (paper)

[en] Batch's disease (BD) is a multisystem disorder of unknown aetiology, characterized by recurrent oral ulcers, genital ulcers, uveitis, skin lesions, and pathergy. Gastrointestinal disease outside the oral cavity is well recognized and usually takes the form of small intestinal ulcers, with the most significant lesions frequently occurring in the ileocaecal region. Symptoms usually include nausea, vomiting, colicky abdominal pain, and change in bowel habit and it is not unusual that patients may present late, with life-threatening complications requiring surgery. Diagnosis has been hindered for many years by limitations in imaging the small bowel and it is usually achieved by means of endoscopy and CT of the abdomen. Magnetic resonance enterography (MRE) is a relatively new technique, which has a high diagnostic rate in patients with Crohns disease (CD). Although many similarities between CD and intestinal B D have already been described in literature, the role of MR E in the evaluation of intestinal B D has never been defined up to now. We report a case of a 12-year-old female patient with diagnosis of BD who presented at our institution for recurrent colicky abdominal pain and diarrhoea. The patient underwent MRE that demonstrated the gastrointestinal involvement

[en] Cystic echinococcosis (CE), also known as ^hydatid disease⁽HD), is a zoonotic infection caused by the larval stage of Echinococcus granulosus, which infects humans as intermediate hosts through the oro fecal route. Carried by the intestinal venous blood, the embryos released by the eggs of the tapeworms can reach every organ, especially the liver, turning into a hydatid cyst. Usually asymptomatic, the cysts can be incidentally detected through radiological examinations performed for other reasons. We show an unusual case of superinfection of a hydatid cyst with typical radiological features of inactivity (WHO-type CE5) with an even rarer skin fistulization passing through a subcutaneous-abdominal abscess involving the right iliac muscle

[en] Two Closed Loop Pulsating Heat Pipes (CLPHPs) are tested on board REXUS 18 sounding rocket in order to obtain data over a relatively long microgravity period (approximately 90 s). The CLPHPs are partially filled with FC-72 and have, respectively, an inner tube diameter larger (3 mm) and slightly smaller (1.6 mm) than the critical diameter evaluated in static Earth gravity conditions. On ground, the small diameter CLPHP effectively works as a Pulsating Heat Pipe (PHP): the characteristic slug and plug flow pattern forms inside the tube and the heat exchange is triggered by thermally driven self-sustained oscillations of the working fluid. On the other hand, the large diameter CLPHP works as a two- phase thermosyphon in vertical position and doesn't work in horizontal position: in this particular condition, the working fluid stratifies within the device as the surface tension force is no longer able to balance buoyancy. Then, the idea to test the CLPHPs in reduced gravity conditions: as the gravity reduces the buoyancy forces becomes less intense and it is possible to recreate the typical PHP flow pattern also for larger inner tube diameters. This allows to increase the heat transfer rate and, consequently, to decrease the overall thermal resistance. Even though it was not possible to experience low gravity conditions due to a failure in the yoyo de-spin system, the thermal response to the peculiar acceleration field (hyper-gravity) experienced on board are thoroughly described. (paper)

[en] Tailoring the structural and electronic properties of 2D materials is fundamental to boost their use in a wide range of technological applications. In this paper, by means of first principles simulations, we show how methyl functionalization of MoS₂ and WS₂ monolayers can be employed to change their energy gap, tune their optoelectronic properties and modify the relative stability of their structural phases (or polytypes). In particular for both compound monolayers, we find that the most stable semiconducting H phase becomes metallic upon methyl functionalization, while in the metastable T′ phase the band gap increases as a function of the –CH₃ coverage; correspondingly the phase stability is reversed and the on-set of the optical absorption is blue-shifted. (paper)

[en] A simple model to evaluate the impedance of a cell in the presence of the generation and recombination of charges is proposed. The analysis is performed by considering a typical asymmetric cell having one electrode perfectly blocking and the other electrode perfectly transparent. The dependence of the impedance of the cell, in the shape of a slab, on the recombination coefficient is investigated. We obtain approximated expressions for the impedance of the cell valid in the low and high frequency regions. The frequencies defining the regions where approximated expressions hold are deduced by means of the asymptotic expansions for the real and imaginary parts of the electrical impedance of the cell.