| Alexander Omelyanchik, Silvia Villa, Federico Locardi, Anna Maria Ferretti, Alessandro Ponti, Gurvinder Singh, Gianni Barucca, Sawssen Slimani, Anna Del Tedesco, Pietro Riello, Bogdan Rutkowski, Marianna Vasilakaki, George Margaris, Kalliopi N. Trohidou, Davide Peddis.“Magnetic Anisotropy and Interactions in Hard/Soft Core/Shell Nanoarchitectures: The Role of Shell Thickness”, Chemistry of Materials, 36(16), 7976−7987 (2024) |
| Abstract: In this work, the influence of shell thickness on the magnetic behavior of hard cobalt ferrite (CoFe2O4) nanoparticles coated with one or more layers of magnetically soft nickel ferrite (NiFe2O4) was investigated. The materials were chosen as model soft and hard magnetics due to their significant difference in the magnetic anisotropy constant, which spans 2 orders of magnitude. The obtained magnetic nanoarchitectures are compositionally graded single crystals, i.e., they comprise a crystallographic coherence of core and shell with no visible core–shell interface at the atomic level. The CoFe2O4 core exhibited an average size of ∼9 nm, while the NiFe2O4 shells were engineered with varying thicknesses of ∼1, 3, and 6 nm. The core/shell nanoarchitectures behave as a single magnetic unit, i.e., in the rigid exchange coupling regime. Nonmonotonic variation of the coercivity with the shell thickness is observed that is attributed to the competition of the different magnetic anisotropies, such as magneto-crystalline and surface, interplaying with the interparticle dipolar interactions. The experimental findings are in good qualitative agreement with Monte Carlo simulation results for a mesoscopic model that includes both the nanoparticle morphology and interparticle interactions. |
| Z. Abdollahi, B. Feizizadeh, B. Shokati, M. Gaiolini, G. Busico, M. Mastrocicco, N. Colombani “Simulating the effects of retreating Urmia Lake and increased evapotranspiration rates on the nearby unconfined aquifer”, Groundwater for Sustainable Development, Volume 26, August 2024, 101307. |
| Abstract: The unsustainable management of water resources along with climate change impacts have led Urmia Lake to severely shrink since 1995. To quantify the groundwater losses in the surrounding area and to avoid the future worsening of a yet worrying scenario a numerical model is needed. For this purpose, a transient state MODFLOW model (2000–2016) has been calibrated and validated versus hydraulic heads. Good model performances were obtained, allowing to accurately estimate the groundwater budget. MODIS dataset was employed to set up the numerical model to identify temporal and spatial extent of evapotranspiration. Evapotranspiration turned out to play a massive contribution in groundwater outflow showing an increasing trend over time. Several scenarios, considering a different way to implement recharge and evapotranspiration in the modelling routine were assessed. The role of the spatialization of the evapotranspiration extinction depth was investigated by averaging remotely sensed heterogeneous datasets over the model domain. No significant differences in model performance indicators were found. Moreover, a model scenario without human groundwater exploitation and land use change was considered. The results slightly differ from the groundwater budget calculated by the validated model and thus indicating the climate change as the major driver of groundwater depletion in the study area. The implementation of such a model allowed for the assessment of the exchange between the lake and the unconfined aquifer, providing a robust foundation for future sustainable management. |
| L. Alessandrino, E. Giuditta, S. Faugno, N. Colombani, M. Mastrocicco “Direct and Remote Sensing Monitoring of Plant Salinity Stress in a Coastal Back-Barrier Environment: Mediterranean Pine Forest Stress and Mortality as a Case Study”, Remote Sensing, Volume 16(17), September 2024, 3150. |
| Abstract: The increase in atmospheric and soil temperatures in recent decades has led to unfavorable conditions for plants in many Mediterranean coastal environments. A typical example can be found along the coast of the Campania region in Italy, within the “Volturno Licola Falciano Natural Reserve”, where a pine forest suffered a dramatic loss of trees in 2021. New pines were planted in 2023 to replace the dead ones, with a larger tree layout and interspersed with Mediterranean bushes to replace the dead pine forest. A direct (in situ) monitoring program was planned to analyze the determinants of the pine salinity stress, coupled with Sentinel-2 L2A data; in particular, multispectral indices NDVI and NDMI were provided by the EU Copernicus service for plant status and water stress level information. Both the vadose zone and shallow groundwater were monitored with continuous logging probes. Vadose zone monitoring indicated that salinity peaked at a 30 cm soil depth, with values up to 1.9 g/L. These harsh conditions, combined with air temperatures reaching peaks of more than 40 °C, created severe difficulties for pine growth. The results of the shallow groundwater monitoring showed that the groundwater salinity was low (0.35–0.4 g/L) near the shoreline since the dune environment allowed rapid rainwater infiltration, preventing seawater intrusion. Meanwhile, salinity increased inland, reaching a peak at the end of the summer, with values up to 2.8 g/L. In November 2023, salts from storm-borne aerosols (“sea spray”) deposited on the soil caused the sea-facing portion of the newly planted pines to dry out. Differently, the pioneer vegetation of the Mediterranean dunes, directly facing the sea, was not affected by the massive deposition of sea spray. The NDMI and NDVI data were useful in distinguishing the old pine trees suffering from increasing stress and final death but were not accurate in detecting the stress conditions of newly planted, still rather short pine trees because their spectral reflectance largely interfered with the adjacent shrub growth. The proposed coupling of direct and remote sensing monitoring was successful and could be applied to detect the main drivers of plant stress in many other Mediterranean coastal environments. |
| N. Colombani, L. Alessandrino, M. Gaiolini, M.P. Gervasio, D. Ruberti, M. Mastrocicco “Unravelling the salinity origins in the coastal aquifer/aquitard system of the Volturno River (Italy)”, Water Research, Volume 263, October 2024, 122145. |
| Abstract: To counteract the ongoing salinization of coastal aquifers, which poses a significant environmental and socioeconomic challenge to local communities, it is necessary to first understand the origin and mechanisms of this phenomenon. This study investigates the origins of salinity in the Volturno River lowland in Southern Italy and reveals that the primary source in the area is paleo-seawater entrapped within sediments that were subject to evapoconcentration processes. By systematically collecting sediment samples at variable depths and locations and extracting porewaters, a comprehensive understanding of the interplay between freshwater and saline water was gained, including complex patterns of vertical stratification of groundwater salinity. The study highlights the limitations of traditional methods that rely on salinity monitoring via integral depth sampling, particularly in capturing the vertical redox and salinity gradients characteristics of layered aquifer/aquitard systems. On the contrary, environmental tracers, like chloride and bromide, provide valuable insights into the sources of groundwater salinity, distinguishing between current seawater intrusion and other causes, such as paleo-seawater and return flow from drained agricultural land. Results suggest that the majority of salinity does not originate from modern seawater intrusion or recent evaporation. Instead, it can be attributed to paleo-seawater affected by evapoconcentration processes. This study has broader implications for the sustainable management of coastal aquifers and the safeguarding of freshwater resources. While our findings are specific to the Volturno River coastal area, the methodologies and insights here presented can be reproduced in every coastal region facing similar salinity challenges. |
| K. Wederni, M. Schiavo, B. Haddaji, Y. Hamed, S. Bouri, N. Colombani “SEAWAT Scenarios Evaluating Links between the Southern Gabès (TN) Confined Aquifer and the Mediterranean Sea”, Water (Switzerland), Volume 16(19), October 2024, 2865. |
| Abstract: The southern Gabès aquifer in southeastern Tunisia faces significant stress due to unsustainable groundwater extraction. This study employs a SEAWAT model to evaluate groundwater losses, salinization mechanisms, and the interaction between the confined aquifer and the Mediterranean Sea. The model, incorporating well pumping rates, regional freshwater inflows from the Matmata Mountain Range, and the Mediterranean Sea boundary, demonstrated high accuracy in simulating hydraulic heads. Findings reveal that regional inflow is only half of the current pumping rate, indicating unsustainable groundwater use. The study also assessed salinity dynamics by modeling the Mediterranean Sea as a constant head and salinity boundary. Results suggest limited exchange between the aquifer and the sea, challenging previous assumptions. While the immediate risks of salinization are low, continued over-extraction could compromise the aquifer’s long-term sustainability. This research highlights the need for stricter local groundwater management, offers insights into regional coastal aquifer interactions, and contributes to global discussions on managing stressed aquifer systems. |
| K. Wederni, B. Haddaji, Y. Hamed, S. Bouri, N. Colombani “Controversial Insights into Irrigation Water Quality in Arid and Semi-arid Regions Using AI Driven Predictions: Case of Southern Gabès”, Groundwater for Sustainable Development, Volume 27, November 2024, 101381. |
| Abstract: Effective groundwater management is critical in arid and semi-arid regions, where water resources are essential for agriculture. This study assesses the Irrigation Water Quality Index (IWQI) of the Southern Gabès aquifer in Tunisia using a combination of traditional hydrochemical analysis and machine learning models—specifically, Classification and Regression Tree (CART) and Support Vector Machine (SVM). A total of 83 groundwater samples were analyzed based on five key parameters: Electrical Conductivity (EC), Sodium Adsorption Ratio (SAR), Chloride (Cl–), Sodium (Na+), and Bicarbonate (HCO3–). The results show that the CART model demonstrated superior performance with an R2 value of 0.99 and a Root Mean Square Error (RMSE) of 0.43, while the SVM model achieved an R2 of 0.87. These findings underscore CART’s robustness in predicting IWQI, offering high precision even with limited datasets. The groundwater quality was categorized, revealing that 62% of samples were classified as “satisfactory” for irrigation, while 31% were deemed “unsuitable” without treatment, highlighting areas of concern for agricultural use. The study also emphasizes the importance of continuous monitoring and adaptive management strategies to ensure sustainable water use in the region. Overall, this research demonstrates the effectiveness of machine learning models, particularly CART, in accurately assessing groundwater quality. These insights provide valuable tools for resource managers to make informed decisions, ensuring the sustainable exploitation of groundwater in arid and semi-arid regions. The findings pave the way for future research and policy development in water resource management. |
| M. Gaiolini, F. Rama, M. Mastrocicco, M. Cosma, S. Donnici, L. Tosi, N. Colombani “Disentangling hydrodynamic drivers of the Southern Venice (Italy) coastal aquifer via frequency decomposition analysis: Insights, challenges, and limitations”, Journal of Hydrology: Regional Studies, Volume 56, December 2024, 102039. |
| Abstract: Study region: Shallow coastal aquifer located in the southern part of the Venice lagoon (Italy). Study focus: This study aims to improve the understanding of coastal aquifers’ hydrodynamics by implementing systematic time-series analyses of data. A collection of non-intrinsically consistent time series from hydrological (surface water and groundwater) and meteo-mareographic monitoring networks was obtained from different institutions. Each signal was broken down through a frequency decomposition analysis, isolating the main driving forces to focus on phenomena that occur at different time and spatial scales. New hydrological insights for the region: Results highlighted that the aquifer is highly connected with the Venice lagoon, with a clear fluctuation of piezometric heads induced by tidal major constituents, decreasing landward. Besides, the effects exerted by reclamation canals and pumping stations were also determined and found to increase landward. Despite the relatively simple behaviour of piezometric heads, the groundwater salinity is influenced by additional local factors, like probe depth, wells’ screen length, and vertical salinity distribution along the aquifer. These findings suggested how to make use of limited and sparse data to enhance the conceptual model of coastal aquifer hydrodynamics, while highlighting the limitations of existing monitoring networks. This outcome justified the need for an intrinsically-consistent network of dedicated multi-level samplers to avoid intra-borehole mixing and reliably characterize the groundwater salinity distribution. |
| P. Habakaramo Macumu, M. Gaiolini, A Ofori, M. Mastrocicco, N. Colombani “Additional sources of salinity and heavy metals from plant residues of peaty horizons in the Po River lowland (Italy)”, Science of the Total Environment, Volume 957, December 2024, 177671. |
| Abstract: The Po River lowland (Italy) is suffering of soil and surface water salinization due to seepage of saline groundwater into drainage canals of agricultural lands. The main drivers are paleo-saline porewaters trapped in peaty and silty clay lenses, deposited in back barrier and lagoonal environments. To study this phenomenon, a 2-ha tile drained agricultural field, experiencing dramatic crop yield decrease in the last years, was selected. The field is located in a reclaimed area at approximately 3 m below sea level in the Ferrara province, 24 km from the Adriatic Sea. To delineate the salinity gradients, 10 high resolution vertical profiles of soil cores were collected with a manual auger corer and analysed in laboratory for EC, pH, grain size, organic matter content, major ions and trace elements. The composition of porewater’s leaching fraction (LF) was gained via deionized water batch extraction with solid liquid ratio 1:5, while the plant available water (PAW) was obtained via microwave hot water extraction in three selected profiles. Linear correlation matrix, principal components analysis (PCA), LF and PAW depth profiles were employed to gain insights on the salinity sources. Stratigraphical cores were almost homogeneous with the most permeable layers constituted by peats. An average porewater salinity of 8.2 g/L with a downward increasing trend was found, with slight acidic pH and very high content of organic matter. PCA highlighted the strong connection among some trace elements (like As, Cd, Cr, Li, Pb, Se), NH4+ and the saline peaty horizons. The PAW salinity was up to two times the LF, highlighting that peaty aquitards are the major saline source in these reclaimed lands. A new salinizing mechanism was then postulated, since plant tissue fragments can store much more salts than the mineral fraction and can act as a long-term source of diffusion driven salinization, so far neglected. |
| M. Gaiolini, N. Colombani, V. Chierici, L. Montanari, M. Mastrocicco “Numerical Modelling of Groundwater Level and Salinity Evolution in a Low-Lying Coastal Area Under Intensive Agricultural Activity”, Water Resources Management, December 2024, https://doi.org/10.1007/s11269-024-04044-y. |
| Abstract: The groundwater salinity changes of the coastal unconfined aquifer of the Po Delta (Italy) from 2010 to 2020 were assessed via a density-dependent numerical model implemented with SEAWAT 4.2. The temporal discretization was defined on a monthly basis, allowing for detailed analysis of the evolution of salinity stratification within the aquifer and of the vertical fluxes induced by the reclamation drainage network. The validated model was used to unravel surface-groundwater interaction fluxes and the long-term impacts induced by the ongoing climate change. The simulation highlighted that deeper layers experienced a salinity increase due to the presence of hyper saline low permeability lenses, while shallow layers experienced both increasing and decreasing salinization trends, depending on the temporal and areal distribution of local factors such as recharge and evapotranspiration, the connection between the shallow aquifer and the drainage network, and the presence of a seawater wedge along the coastline. The sensitivity analysis performed on the maximum plant salt uptake due to evapotranspiration revealed a slight variation in the accumulated salinity mass and concentration within the aquifer, resulting in a maximum error of less than 2% at the end of the simulation. |
| Jacopo Donnini, Alessandra Mobili, Gianluca Maracchini, Gianluca Chiappini, Francesca Tittarelli, Valeria Corinaldesi. “A multi-performance comparison between lime, cementitious and alkali-activated TRM systems: Mechanical, environmental and energy perspectives”, Construction and Building Materials, Volume 440, August 2024, 137396. |
| Abstract: The combined need to propose new solutions for the structural reinforcement of existing buildings and for the reduction of CO2 emissions is leading to the development of more sustainable composite materials, such as those based on alkali-activated mortars (AAM). In this study, different formulations of AAM, based on metakaolin or fly ash, have been evaluated as possible matrices for Textile Reinforced Mortar (TRM) systems. Two different bidirectional textiles, made of AR glass or basalt fibers, were used as internal reinforcement. The physical-mechanical properties of TRM systems based on AAM were evaluated and compared with those of commercial systems with cementitious or lime-based matrices. Direct tensile tests on TRM coupons and shear bond tests on clay brick substrates were carried out. Then, their energy and environmental-related performance have been compared. Results showed that alkali-activated matrices can be very promising and eco-friendly alternative solutions to traditional mortars in TRM systems. |
| Liana Lucchetti, Giovanni Nava “Nonlinear optical director reorientation in heliconical cholesteric liquid crystals: a brief review”, Giant, Volume 19, August 2024, 100311. |
| Abstract: Cholesteric liquid crystals, also known as chiral nematics, possess a right-angle helicoidal structure with pitch in the submicrometer and micrometer range. Although the possibility of getting optical reorientation in this kind of materials has been considered since the discovery of giant optical nonlinearity in nematic liquid crystals, a significant light-induced modulation of the helical structure has shown to be a challenging task. The recent experimental realization of a chiral phase with an oblique helicoidal structure, identified as the heliconical phase predicted by Meyer and DeGennes in 1968, offers the opportunity to observe such an optical reorientation of the optic axis. This paper is a brief review of the nonlinear optical properties of these unconventional chiral nematic liquid crystals and is aimed at showing that the world of liquid crystalline phases can still amaze with new material properties and new physics. © 2024 The Author(s) |
| Cristian Patiño Vidal, Cristina Muñoz-Shugulí, Manon Guivier, Debora Puglia, Francesca Luzi, Adrián Rojas, Eliezer Velásquez, María José Galotto, López-de-Dicastillo, C. (2024). PLA-and PHA-Biopolyester-Based Electrospun Materials: Development, Legislation, and Food Packaging Applications. Molecules, 29(22), 5452. |
| Abstract: The high accumulation of plastic waste in the environment has led to great interest in biodegradable polymers, such as polylactic acid (PLA) or polyhydroxyalkanoates (PHAs). Their benefits, combined with the application of electrospinning technology, represent an innovative proposal for the food packaging industry. This article provides a comprehensive review of the latest developments of PLA- and PHA-biopolyester-based electrospun materials for food packaging applications, summarizing the reported technologies, material properties, applications, and invention patents. In addition, the legislation used to assess their biodegradability is also detailed. Electrospun packaging materials are largely developed through uniaxial, coaxial, emulsion, multiaxial, and needleless techniques. PLA- and PHA-biopolyester-based electrospun materials can be obtained as single and multilayer packaging structures, and the incorporation of natural extracts, organic compounds, and nanoparticles has become a great strategy for designing active food packaging systems. The biodegradability of electrospun materials has mainly been evaluated in soil, compost, and aquatic systems through ASTM and ISO normatives. In this review, the dependence of the biodegradation process on the polymer type, conditions, and test methods is clearly reviewed. Moreover, these biodegradable electrospun materials have shown excellent antioxidant and antimicrobial properties, resulting in a great method for extending the shelf life of fruits, bread, fish, and meat products. |
| Catia Clementi, Francesca Luzi, Franco Dominici, Fabio Marmottini, Riccardo Vivani, Loredana Latterini, Debora Puglia, (2024). Development of MOF-Pigment Hybrids to Implement a Sustainable Coloration of Poly (ε-caprolactone) Composites. ACS Sustainable Chemistry & Engineering, 12(33), 12525-12533. |
| Abstract: A sustainable strategy to improve aesthetic and mechanical properties of poly-(ε-caprolactone) (PCL) is proposed relying on the use of MIL53(Al) metal organic framework (MOF) as filler and hosting matrix for natural dyes extracted from logwood (LW). Three purple pigments are prepared by combining the aqueous extract of LW with MOF, previously prepared and differently dried with three methods to optimize the dye load. The three pigments are obtained with high reaction mass efficiency (RME) values (44–66%). According to the optical and structural characteristics, the color is caused by hematein-aluminum chelates, which are formed when logwood dye molecules interact with the bulk or surface unsaturated aluminum centers of the MOF, depending on how much the matrix has dried out. The pigments are combined in different amounts (1, 3, and 5 wt %) with PCL effectively imparting purple-violet shades (ΔE* ≈ 32–55), while also enhancing its mechanical and thermal characteristics. Tensile characterization results for PCL composites verify the contribution of nanostructured fillers in enhancing stiffness and strength up to 3% by weight, with only a little reduction in ductility. Variable color and tensile qualities are sustainably and effectively given to the PCL polymer by using MOF-LW fillers. |
| Elisa Mammoliti, Sara Ciattoni, Mirko Francioni, Gregorio Baiocchi, Veronica Gironelli, Stefano Mazzoli, “Controls of lithology and degree of fracturing on the in-situ estimation of rock mass hardness using the Equotip hardness tester”, Bulletin of Engineering Geology and the Environment, Volume 83, November 2024. |
| Abstract: The use of the Equotip hardness tester in engineering geology has increased significantly in recent years, especially in estimating the strength of weak and weathered rock materials. Weathering and fracturing, besides lithology, influence the overall behaviour of the rock mass and the response of the non-destructive tester. In this study, more than 9,000 Equotip rebound measurements were collected from twelve rock outcrops of several geological formations in central Italy, using a regular measurement grid approach. In addition, linear scan lines were combined with the analysis of photogrammetric sampling windows to determine geomechanical indexes such as Rock Quality Designation (RQD), Joint Volumetric Count (Jv) and Fracture intensity (P21) to be coupled with the Equotip measurements. A strong correlation was found between RQD, Jv, P21 and the Equotip rebound. The study presents an innovative approach by integrating extensive Equotip rebound measurements with geomechanical indices (RQD, Jv, P21) and advanced photogrammetric techniques. This combination provides new quantitative constraints on the relationship between fracture intensity, lithological variation, and mechanical properties of rock masses. Our findings highlight the potential of Equotip testing as a fast and reliable tool for in-situ rock mass quality assessment, also in heterogeneous geological settings, improving hazard management and engineering design. |
| Degradation behavior of austenite, ferrite, and martensite present in biodegradable Fe-based alloys in three protein-rich pseudo-physiological solutions Abdelhakim Cherqaoui, Quang Nguyen Cao, Maria Laura Gatto, Carlo Paternoster, Paolo Mengucci, Diego Mantovani, Bioactive Materials 41 (2024) 96–107 |
| Abstract: This study investigates the degradation behavior of three distinct Fe-based alloys immersed in three pseudophysiological solutions. These alloys, which have varied Mn and C contents, include a commercially available Fe-0.15C alloy, namely Fe–C, and two newly developed alloys, that is Fe–5Mn-0.2C (namely Fe–5Mn) and Fe–18Mn-0.6C (namely Fe–18Mn). The aim was to understand the effect of alloying elements and the testing solution on the in-vitro degradation behavior of these Fe-based materials. Static immersion degradation and potentiodynamic corrosion tests were carried out using three pseudo-physiological solutions with albumin supply, that is modified Hanks’ saline solution (MHSS), phosphate buffered saline solution (PBS), and sodium-chloride solution (NaCl). After two weeks of static immersion, the results revealed that Fe–5Mn, characterized by a mixture of ferrite and martensite, showed the highest degradation rate, while Fe–C, composed solely of ferrite, showed the lowest rate of degradation. The predominant degradation products in MHSS and PBS were phosphates and carbonates. In PBS, these products formed a remarkably stable protective layer on the surface, contributing to the lowest degradation rate. In contrast, porous hydroxides appeared as the main degradation products for samples immersed in NaCl solution, leading to the highest degradation rate. These results provided important insights into the customization of Fe–Mn–C alloys for a range of biomedical applications, meeting a variety of clinical requirements, and highlighting the considerable potential of Fe–Mn–C alloys for biomedical applications. |
| Physical and chemical surface modification by laser polishing of CuZn42 parts produced by laser powder bed fusion Andrea Gatto, Riccardo Groppo, Maria Laura Gatto, Eleonora Santecchia, Daniel Munteanu, Paolo Mengucci, Surfaces and Interfaces 54 (2024) 105228 |
| Abstract: The widespread use of Cu-Zn alloys containing lead (Pb) in plumbing applications poses significant health risks due to potential Pb leaching into drinking water. In response to international legislation aimed at reducing or eliminating Pb in metal alloys, there is an increasing demand for environmentally friendly brass. In this experimental work, authors show that during the Laser Beam Powder Bed Fusion (PBF-LB) process of the CuZn42 (CW510L) alloy, small particles only a few microns large mixed with large particles that are hundreds of microns in size, are spattered from the material. Large particles show average Zn/Cu ratio around 0.22, while for small particles it increases up to 3, against a nominal value of 0.72 for the CW510L alloy. The fallout of such particles on the produced part enriches surface of Zn, thus altering the surface chemical composition with an increase in Zn concentration beyond the acceptance limit of 43 at.%. To restore the standard chemical composition of the surface, a treatment based on the ablation of the surface material by a laser beam was proposed. Results clearly show that, after the laser treatment, the chemical composition of the surface is completely restored, and the standard properties recovered. |
| Alesiani, P., & Ruggeri, P. (2024). “Assessment of Load Test Results on a Sheet Pile Quay Wall: The Potential of 3D Numerical Modeling”. Journal of Geotechnical and Geoenvironmental Engineering, 150(9), 05024007. |
| Abstract: A full scale load test on the apron is a very effective method for validating the design of a new operative quay wall. The availability of the monitoring data from the load test on a sheet pile wall of a major Italian port and the well-known geotechnical context of the site made it possible to explore the potential of three-dimensional (3D) numerical modeling to understand the response of the work to the applied load. In order to achieve a good match between real observations and numerical results, the limited impact of the working load on a robust geotechnical structure, the use of advanced constitutive models for soils and careful modeling of the construction phases and details of the work were taken into consideration. For this reason, the procedure adopted to calibrate the numerical model based on geotechnical test results is presented after the description of the load test monitoring data. Thanks to these efforts, the 3D numerical model, validated on the monitored data, allowed us to gain further insights on the structural behavior of the quay wall during construction and loading phases, underlining the relevant role played by some apparently marginal and often ignored details. |
| Andrea Gatto, Emanuele Tognoli, Riccardo Groppo, Marcello Cabibbo, Maria Laura Gatto, Simona Sabbatini, Paolo Mengucci, “Reactive formation of C3N4 as a by‑product of AISI 1070 parts produced by laser powder bed fusion in N2 atmosphere”, Progress in Additive Manufacturing, September 2024, https://doi.org/10.1007/s40964-024-00785-9. |
| Abstract: In metal additive manufacturing (AM), inert gases are traditionally used to achieve a controlled atmosphere and mitigate the effects of residual reactive gases. However, the interaction between gases and laser processes, particularly in reactive laser powder bed fusion (RL-PBF) technology, offers the possibility of opening up new avenues for material synthesis. In this experimental work, the authors observed the presence of C3N4 in the residual powder during the manufacture of AISI 1070 steel parts by L-PBF, indicating a reactive process occurred during parts production. This investigation revealed the formation in the working chamber of a waste product containing C3N4 carbon nitride, due to the reaction between the carbon released from the steel and the nitrogen in the chamber. Remarkably, despite carbon depletion, the final product of AISI 1070 steel complies with the specifications of use. Hence, the L-PBF machine was modified to allow black powder sampling from various locations in the chamber. Authors attempted to enhance the production of the C3N4 material by increasing the SED up to 7143 J/mm2 to sublimate a pure graphite rod and concurrently manufacture parts in AISI 1070, in a nitrogen atmosphere. The results obtained at higher SED values showed that in both cases (graphite rod or AISI 1070 steel) a C3N4 compound in the black powder is formed in the investigated atmosphere by reaction of nitrogen atoms with the carbon atoms vaporized by the laser beam. Thus, the study highlights the novel achievement of synthesizing carbon nitride as a high-value by-product while producing functional AISI 1070 steel parts via L-PBF through reaction with nitrogen atmosphere. |
| Serena Summa, Giada Remia, Costanzo Di Perna, Francesca Stazi, Mechanically ventilated classrooms in central Italy’s heritage school buildings: Proposal of archetypes and CO2 prediction models, Building and Environment, Volume 265, 01/11/2024, 111963, ISSN 0360-1323, https://doi.org/10.1016/j.buildenv.2024.111963. |
| Abstract: This study proposed a typological analysis to identify the archetypes of classrooms equipped with controlled mechanical ventilation (CMV) in Italy and an experimental campaign on 58 typical classrooms to identify the main indoor microclimatic characteristics and CO2 concentrations. From the analyses carried out, general information was gathered on the heating systems and the main energy and acoustic improvements carried out in the schools. The typological analysis identified four different types of mechanical ventilation systems installed in three different classroom archetypes: wide, square and deep, with percentages of window area of 25 %, 30 % and 40 % respectively. The field measurement campaign showed that, in terms of CO2 concentration, mechanical ventilation was effective in the winter period, while in the mid-season and summer periods, natural ventilation was predominant due to the opening of windows by the occupants. Furthermore, in the case of manual control, incorrect use of the machine by the occupants, who reported noise-related problems or insufficient user training, resulted in CO2 levels above the recommended limits. Multivariate regressions developed for schools equipped with CMVs predicted maximum and average CO2 concentrations as a function of minimum and maximum indoor and outdoor temperatures with a significance (R2, correct) of 76 % and 83 % respectively. |
| Serena Summa, Luca Tarabelli, Costanzo Di Perna, Francesca Stazi, Data-driven automation of HVAC systems: An experimental study in a university study room, Journal of Building Engineering, Volume 95, 15/10/2024, 110166, ISSN 2352-7102, https://doi.org/10.1016/j.jobe.2024.110166. |
| Abstract: This study proposes a framework for controlling HVAC systems for university study rooms that includes a data-driven model capable of identifying the probability of user interaction with air conditioning and ventilation systems, depending on the thermal sensation vote (TSV), perceived air quality (PAQ) and microclimate parameters (air and operative temperature, air velocity, relative humidity and CO2). The experimental setup allowed the participants to carry out their usual study/work activities without the need to be supervised. This allowed the occupants not to be psychologically conditioned and made their experience and interaction with the environment/systems as realistic as possible. The analysis of the experimental data showed that the operative temperature mainly influences the thermal sensation of the occupant inside the room, while the perceived air quality depends not only on the CO2 concentration but also on thermal perception and air velocity. Furthermore, three predictive models (heating, cooling and IAQ) were obtained from the experimental data, indicating the probability of user interaction with the system (R2 between 0.85 and 0.94). The heating phase model was also verified by automatizing the heating system through the developed framework and comparing the user’s sensations before and after control (users unaware of the changes). The use of the models increased users’ thermal comfort from 39 % to 82 %, confirming the effectiveness of the system. |
| O. Roig, S. Summa, C. Pardal, A. Isalgue, C. Di Perna, F. Stazi, Opaque ventilated façades: Energy performance for different main walls and claddings, Energy and Buildings, Volume 314, 01/07/2024, 114280, ISSN 0378-7788, https://doi.org/10.1016/j.enbuild.2024.114280. |
| Abstract: Ventilated façades can reduce heat gains through the opaque envelope of buildings, and consequently help to lower the cooling energy demand and the relative greenhouse gas emissions. However, the influence of the design features and climatic variables on their energy performance is not known enough. In this article, the influence of different parameters of the ventilated façade has been assessed. The cladding material, the relative position between mass and thermal insulation in the main wall, the air cavity geometry, and the open/closed joint configurations have been evaluated through a numerical calculation with a model that considers all these parameters, validated with experimental data. It has been observed that, in summer conditions, the best strategy to prevent heat gains is to block the energy in the outermost layers. This suggests adopting non-thermal conductor materials for claddings and the insulation of the main wall on the outer layer. Higher cavities imply a reduction of the ventilation benefits; the air remains more time in the cavity, and thus heat fluxes per unit façade area increase. On the contrary, lower air cavities allow more fresh air entrances from outside, as occurs for open joint claddings, reducing net heat gains. Additionally, widening the air cavity, up to 10 cm, results in lower average heat flux. All these different façade configurations are compared in a cradle-to-gate environmental impact assessment demonstrating that the lowest energy-demanding solution during the service life might not be the best one in the whole life cycle, thus a deeper study is needed. |
