Relationship between rainfall and water table in a coastal aquifer: the case study of Castelporziano presidential estate

This study is focused on the analysis of seasonal and annual variability in groundwater levels of the coastal aquifer of Castelporziano Presidential Estate, a protected area of 59 Km2 located in the periphery of Rome. A comparison with the local trends of rainfall at “Castello” gauging station at different time scales (monthly, seasonal and annual) has been carried out. The results highlight differences between the coastal area and eastern and northern sector of the Estate. Indeed, the seasonal effect due to local meteoric recharge is direct and regular during the year in the coastal area in respect to the eastern and northern sectors of the Estate. Moreover, annual steady regime and multi-year trend of groundwater levels suggest the contribution from the adjacent volcanic aquifer of Albani Hills. In the latter case, the regional circulation of groundwater is affected by the effects of intense withdrawals. The maintenance of the monitoring network will allow to define the flow paths of the groundwater that characterize the coastal aquifer of Castelporziano

Chronic constipation diagnosis and treatment evaluation: The "CHRO.CO.DI.T.E." study

Background: According to Rome criteria, chronic constipation (CC) includes functional constipation (FC) and irritable bowel syndrome with constipation (IBS-C). Some patients do not meet these criteria (No Rome Constipation, NRC). The aim of the study was is to evaluate the various clinical presentation and management of FC, IBS-C and NRC in Italy. Methods: During a 2-month period, 52 Italian gastroenterologists recorded clinical data of FC, IBS-C and NRC patients, using Bristol scale, PAC-SYM and PAC-QoL questionnaires. In addition, gastroenterologists were also asked to record whether the patients were clinically assessed for CC for the first time or were in follow up. Diagnostic tests and prescribed therapies were also recorded. Results: Eight hundred seventy-eight consecutive CC patients (706 F) were enrolled (FC 62.5%, IBS-C 31.3%, NRC 6.2%). PAC-SYM and PAC-QoL scores were higher in IBS-C than in FC and NRC. 49.5% were at their first gastroenterological evaluation for CC. In 48.5% CC duration was longer than 10 years. A specialist consultation was requested in 31.6%, more frequently in IBS-C than in NRC. Digital rectal examination was performed in only 56.4%. Diagnostic tests were prescribed to 80.0%. Faecal calprotectin, thyroid tests, celiac serology, breath tests were more frequently suggested in IBS-C and anorectal manometry in FC. More than 90% had at least one treatment suggested on chronic constipation, most frequently dietary changes, macrogol and fibers. Antispasmodics and psychotherapy were more frequently prescribed in IBS-C, prucalopride and pelvic floor rehabilitation in FC. Conclusions: Patients with IBS-C reported more severe symptoms and worse quality of life than FC and NRC. Digital rectal examination was often not performed but at least one diagnostic test was prescribed to most patients. Colonoscopy and blood tests were the "first line" diagnostic tools. Macrogol was the most prescribed laxative, and prucalopride and pelvic floor rehabilitation represented a "second line" approach. Diagnostic tests and prescribed therapies increased by increasing CC severity

Microstructural and Thermo-Mechanical Characterization of Cast NiTiCu20 Shape Memory Alloy

Among NiTi-based alloys, one of the most promising and exploited alloys is NiTiCu, since the addition of Cu in substitution of Ni in the binary equiatomic NiTi has a significant influence on the martensitic transformation and the thermomechanical properties of the system. A high content of Cu improves the damping properties at the expense of phase homogeneity and workability. The present study focuses on an alloy with a high copper content, i.e., 20 at.%. For this specific composition, the correlation between the thermal treatments, microstructure, formation of secondary phases, and damping properties are investigated by several analyses. The microscopic observation, together with the compositional analysis, allowed the determination of four different phases in the alloy. Both the calorimetry and dynamic thermo mechanical measurements, which confirmed the high damping ability of the alloy, provided a characterization of the martensitic transition. Finally, the electron backscatter diffraction (EBSD) analysis detected the different crystallographic structures (i.e., cubic austenite, orthorhombic martensite, and cubic (face-centered) NiTi2) and their orientation in the different phases. Therefore, the present work aims to improve the knowledge of the role of secondary phases in the optimization of the NiTiCu20 alloy as a valuable alternative to typical alloys used for damping purposes

A Study on Damping Property of NiTi Elements Produced by Selective Laser‐Beam Melting

The damping properties of NiTi elements produced through selective laser melting are investigated by tuning the process parameters. To this end, twelve parameters’ sets are selected to fabricate fully-dense NiTi specimens. Damping is evaluated through loss factor index, mechanical loading cycles (up to 104 cycles), solicitation frequency and strain amplitude. Results confirm that NiTi fabricated through selective laser-beam melting is an excellent candidate to substitute conventional materials when used in the martensite phase. Furthermore, the selected process parameters enable specific damping performances that can be collected in damping maps which turn out to be practical tools for the fabrication of NiTi parts with tunable damping response

Applications of Shape Memory Alloys for Neurology and Neuromuscular Rehabilitation

Shape memory alloys (SMAs) are a very promising class of metallic materials that display interesting nonlinear properties, such as pseudoelasticity (PE), shape memory effect (SME) and damping capacity, due to high mechanical hysteresis and internal friction. Our group has applied SMA in the field of neuromuscular rehabilitation, designing some new devices based on the mentioned SMA properties: in particular, a new type of orthosis for spastic limb repositioning, which allows residual voluntary movement of the impaired limb and has no predetermined final target position, but follows and supports muscular elongation in a dynamic and compliant way. Considering patients in the sub-acute phase after a neurological lesion, and possibly bedridden, the paper presents a mobiliser for the ankle joint, which is designed exploiting the SME to provide passive exercise to the paretic lower limb. Two different SMA-based applications in the field of neuroscience are then presented, a guide and a limb mobiliser specially designed to be compatible with diagnostic instrumentations that impose rigid constraints in terms of electromagnetic compatibility and noise distortion. Finally, the paper discusses possible uses of these materials in the treatment of movement disorders, such as dystonia or hyperkinesia, where their dynamic characteristics can be advantageous

A novel sintering method for polycrystalline NiMnGa production for elastocaloric applications

NiMnGa Heusler alloy plays a key role as reference system for ferromagnetic shape memory alloys (FeSMAs) and their peculiar functional properties including large magnetic-field-induced strain, magnetocaloric and elastocaloric effects. Moreover, the microstructure of polycrystalline NiMnGa alloys has been investigated and optimized to improve the mechanical properties and to reduce their typical brittleness. For this reason, increasing interest has been devoted to different kinds of fabrication routes for this alloy, such as powder metallurgy processes. In the present study, a polycrystalline Ni50Mn30Ga20 (atomic %) alloy is produced by means of an unconventional sintering method that involves the canning of powders and the subsequent processing by hot rolling. This process was implemented according to the results obtained by means of the open die pressing (ODP) sintering of NiMnGa which was investigated in a previous work. The present study is aimed at developing an alternative and cost-effective sintering method for the consolidation of fully-dense NiMnGa samples. The process allowed reducing the intrinsic brittleness of the alloy. A heat treatment at 925 °C for 6 h was applied and allowed achieving a maximum adiabatic ΔT of +6.3 °C and - 4.5 °C with a strain of 4 % and a strain rate of 400 %/min in compression. The novel method led to very promising elastocaloric properties, making NiMnGa a suitable candidate for solid-state cooling and heating applications

A Study of a Cryogenic CuAlMn Shape Memory Alloy

In extreme temperature environments, a newly emerging engineering application involves both the active and passive control of structures using cryogenic shape memory alloys, which are smart materials able to recover high deformation below the freezing point. With the objective of carrying out new advances in this area, the present work aims to investigate the Cu-7.5Al-13.5Mn (wt.%) shape memory alloy. Thermal, microstructural, and thermomechanical analyses of as-cast and hot-rolled specimens were performed, taking into account the effects of annealing and solubilization. It was observed that the phase transition occurs at temperatures below 120 K and changes according to the thermo-mechanical path. Specifically, hot-rolling lowers the phase transition temperature range with respect to the as-cast condition–from 34 K to 23 K for Mf, and from 89 K to 80 K for Af. Additionally, when the annealing temperature rises, the phase transformation temperature increases as well, and the alloy loses its cryogenic features when heat treated above 473 K. Finally, loss factors of 0.06 and 0.088, which were respectively found in dynamic and static settings, validate the material’s good damping response

Study of pseudoelastic systems for the design of complex passive dampers: Static analysis and modeling

This work presents an experimental and numerical analysis of several parallel systems of NiTi pseudoelastic wires. Standard tensile tests were accomplished to evaluate the global damping capacity, the energy dissipated per cycle and the maximum attenuated force in a static condition. Besides, a numerical model was implemented to predict the damping response of more complex pseudoelastic arrangements. It was found a damping capacity upper limit of 0.09 regardless the number and the length of the NiTi components. In addition, it was found that the energy dissipated per cycle is related to the strain and to the number of the NiTi components; furthermore, the system composed of NiTi wires with different length allows for an elastic region that is related to the numbers of wires and that presents a modulation of the stiffness. Finally, the proposed numerical model allows a precise design of complex pseudoelastic combinations as it is able to represent the rhombohedral characteristic

Elastocaloric Properties of Polycrystalline Samples of NiMnGaCu Ferromagnetic Shape Memory Alloy under Compression: Effect of Improvement of Thermoelastic Martensitic Transformation

Shape memory alloys (SMAs) and ferromagnetic shape memory alloys (FeSMAs) have recently attracted interest for solid state refrigeration applications. Among NiMnGa-based quaternary systems, NiMnGaCu exhibits an interesting giant magnetocaloric effect thanks to the overlapping of the temperatures related to the magnetic transition and the thermoelastic martensitic transformation (TMT); in particular, for compositions with Cu content of approximately 6 at%. In the present work, we investigated the improvement effect of TMT on the total entropy change (ΔS) in the elastocaloric performances of polycrystalline Ni50Mn18.5Cu6.5Ga25 at% alloy samples, just above room temperature. We report an extensive calorimetric and thermomechanical characterization to explore correlations between microstructural properties induced by the selected thermal treatment and elastocaloric response, aiming at providing the basis to develop more efficient materials based on this quaternary system. Both ΔT and ΔS values obtained from mechanical curves at different temperatures and strain recovery tests under fixed load vs. T were considered. Maximum values of ΔS = 55.9 J/KgK and ΔT = 4.5 K were attained with, respectively, a stress of 65 MPa and strain of 4%. The evaluation of the coefficient of performance (COP) was carried out from a cyclic test

Towards an understanding of the functional properties of NiTi produced by powder bed fusion

In this work, near fully dense NiTi components have been fabricated using a 55.2Ni-Ti (wt.%) powder through selective laser beam melting. The effect of the manufacturing process on mechanical and functional properties of the selected NiTi alloy has been systematically investigated by tuning the hatching distance, h, and the scanning speed, v, in order to define a set of 12 NiTi families. The as-built NiTi parts present phase transformation temperatures higher than those of the feedstock, ascribed to the depletion of Ni during the process. Pseudoelasticity and shape memory responses have been evaluated through uniaxial compression and bending measurements, respectively. Both quasi-static and dynamic analyses have been considered. It is shown that the resulting material may exhibit distinct damping and strain recovery responses depending on the used process parameters