IRIS Università degli Studi dell'Aquila
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Benchmarking the design of the cryogenics system for the underground argon in DarkSide-20k
Get PDFDarkSide-20k (DS-20k) is a dark matter detection experiment under construction at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. It utilises ∼100 t of low radioactivity argon from an underground source (UAr) in its inner detector, with half serving as target in a dual-phase time projection chamber (TPC). The UAr cryogenics system must maintain stable thermodynamic conditions throughout the experiment’s lifetime of over 10 years. Continuous removal of impurities and radon from the UAr is essential for maximising signal yield and mitigating background. We are developing an efficient and powerful cryogenics system with a gas purification loop with a target circulation rate of 1000 slpm. Central to its design is a condenser operated with liquid nitrogen which is paired with a gas heat exchanger cascade, delivering a combined cooling power of more than 8 kW. Here we present the design choices in view of the DS-20k requirements, in particular the condenser’s working principle and the cooling control, and we show test results obtained with a dedicated benchmarking platform at CERN and LNGS. We find that the thermal efficiency of the recirculation loop, defined in terms of nitrogen consumption per argon flow rate, is 95 % and the pressure in the test cryostat can be maintained within ±(0.1–0.2) mbar. We further detail a 5-day cool-down procedure of the test cryostat, maintaining a cooling rate typically within −2 K/h, as required for the DS-20k inner detector. Additionally, we assess the circuit’s flow resistance, and the heat transfer capabilities of two heat exchanger geometries for argon phase change, used to provide gas for recirculation. We conclude by discussing how our findings influence the finalisation of the system design, including necessary modifications to meet requirements and ongoing testing activities
Synergistic benefits of AMF: development of sustainable plant defense system
Get PDFArbuscular mycorrhizal fungi (AMF) are a ubiquitous group of soil microorganisms that form symbiotic relationships with the roots of over 80% of terrestrial plant species. These beneficial fungi are crucial in plant growth, nutrition enhancement, and abiotic and biotic stress resilience. This review explores the AMF synergistic benefits including their capacity to interact with plant roots system to enhance nutrient absorption, improve stress resilience, and confer disease resistance, and their potential applications in sustainable agriculture. The Review integrates recent insights illustrating the molecular processes responsible for improving plant defense mechanisms by AMF, including the modulation of signaling pathways. It highlights the importance of AMF-induced systemic resistance in enhanced abiotic and biotic stress resistance. Moreover, the article provides an integrative perspective on applying AMF toward sustainable plant protection. Within this context, we discussed how these fungi improve plant performance, including enhanced nutrient acquisition, increased tolerance to environmental stressors, and enhanced protection against pathogens by improving plant resistance to biotic stress through the activation of the plant immune system. We also examine the ecological significance of AMF in maintaining soil health and fertility and highlight the importance of incorporating their management into sustainable agricultural practices. Future research directions and innovative applications are also presented. The literature survey demonstrated these fungi's versatility in improving plant tolerance to several biotic and abiotic stresses. At the scientific level, these abilities are supported by several open-field experiments on different plant species. Available commercial formulations and positive ongoing research of AMF, in combination with other sustainable tools, highlight the solid research outline on these beneficial fungi
Selection of a Bacterial Conditioner to Improve Wheat Production Under Salinity Stress
Get PDFThis study investigated the isolation and formulation of a bacterial conditioner as a biostimulant for Triticum durum (durum wheat) under salinity stress. An Algerian alkaline-saline soil was sampled, characterized for its physical and chemical characteristics and its culturable and total microbial community (16S rRNA gene metabarcoding). Three bacterial strains showing high 16S rRNA gene similarity to Pseudomonas putida, Bacillus proteolyticus, and Niallia nealsonii were selected for their plant growth-promoting (PGP) traits under different salinity levels, including phosphate solubilisation (194 mu g mL-1), hormone production (e.g., gibberellin up to 56 mu g mL-1), and good levels of hydrocyanic acid, ammonia, and siderophores. N. nealsonii maintained high indole production under saline conditions, while B. proteolyticus displayed enhanced indole synthesis at higher salt concentrations. Siderophore production remained stable for P. putida and N. nealsonii, whereas for B. proteolyticus a complete inhibition was registered in the presence of salt stress. The consortium density and application were tested under controlled conditions using Medicago sativa as a model plant. The effective biostimulant formulation was tested on Triticum durum under greenhouse experiments. Bacterial inoculation significantly improved plant growth in the presence of salt stress. Root length increased by 91% at 250 mM NaCl. Shoot length was enhanced by 112% at 500 mM NaCl. Total chlorophyll content increased by 208% at 250 mM NaCl. The chlorophyll a/b ratio increased by 117% at 500 mM. Also, reduced amounts of plant extracts were necessary to scavenge 50% of radicals (-22% at 250 mM compared to the 0 mM control). Proline content increased by 20% at both 250 mM and 500 mM NaCl. These results demonstrate the potential of beneficial bacteria as biostimulants to mitigate salt stress and enhance plant yield in saline soils
Architetture del Novecento a L’Aquila tra riconoscimento e uso: il nuovo ospedale di Marcello Vittorini /
Get PDFTwentieth-century hospital complexes are significant examples of how architecture can shape the urban context and the development of cities. However, the significances and the architectural values of these structures are often overlooked and misunderstood; especially when said buildings assume strategic importance, their functions tend to overwhelm and distort the architecture.
The selection of the most significant works of the twentieth century and beyond (from 1945 to today) in Abruzzo seems to ignore hospitals; furthermore, the generally used criteria to assess cultural interest appear to mainly focus on the initial project, neglecting transformations over time and the relationship with places.
Starting from the analysis of 20th-century hospital complexes (particularly the most recent, yet significantly altered, one), we aim to reflect on the need for a long-term vision that allows for the management of change with a view to co-evolution, avoiding disruption and damage to the architectural heritage
Overstrength and variance analysis of angle brackets for timber structures considering the uncertainty in the nail–timber interaction
Get PDFEngineered wood products, along with advanced processing and fabrication, are pushing the limits of modern wood construction. However, the capacities of such systems are often determined by the capabilities of the connections. Typical connections for timber beams consist of angle brackets with annular ring nails. The load-bearing capacity of these connections is usually provided by their producers and is based on experimental testing, where the connection is typically subjected to short-term monotonic loading. However, the variability of angle bracket capacity is generally governed by uncertainties on the timber side, specifically the interaction between nails and wood. This paper presents the experimental results and a parametric numerical element model for predicting the load-bearing capacity of connections with nailed angle brackets, considering the effects of uncertainties in the nail–timber constitutive behaviour. Three metal brackets for beam–column connections are analysed, and their performance in various loading arrangements is examined. Detailed finite element models have been developed for each connection, where the response of each nail is defined by a semi-physical constitutive relationship calibrated on separate axial and transversal tests on isolated nails. The authors propagate the uncertainty in the nail–timber interaction on the capacity of the angle brackets following a Monte Carlo-based approach in the three considered loading scenarios. The generated dataset is used to estimate the overstrength factors of the connections and explain the variance of the estimated capacity values based on a multilinear regression surrogate model
Evaluating Viaduct Surface Cracking on SLAM Point Clouds: Insights from an Italian Case Study
No full textKinematics of Zigzagged Articulated Parallelograms with Articulated Braces (ZAPAB) mechanisms
No full textWe study the kinematics of Zigzagged Articulated Parallelograms with Articulated Braces (ZAPAB) mechanisms, a modular-based bars linkage characterized by a single Lagrange parameter, aimed to supply the microstructure for a third-gradient planar one-dimensional continuum after homogenization. We choose a specific geometry for the constituent planar modules of the ZAPAB mechanism, where each module is built upon rigid bars and hinges (nodes). The hinges are arranged in three layers: upper, middle, and lower. Thus, when perfect constraints are imposed, the placement and the length of each module depend uniquely on the selected Lagrangian parameter: the distance between adjacent, nonconnected nodes associated with the middle layer hinges. In this way, we introduce a mechanism in which a designated set of material points belong to a family of circumferences parameterized by a unique degree of freedom, when neglecting the global rigid motions. We prove, following a symmetry argument, that the allowed configurations for the considered ZAPAB mechanism are circumferences of different radii. Furthermore, given a reference length of the mechanism, we prove that, in the limit of a large number of modules, the length of the mechanism does not vary as the Lagrange parameter changes: the mechanism is inextensible. We give the analytical expression for the curve traced by the terminal point of ZAPAB mechanism. Therefore, this configuration of ZAPAB structure is a candidate to represent a synthesis for a particular class of third-gradient one-dimensional continua: those that are inextensible and whose deformation energy depends on the derivative of the curvature, with respect to its curvilinear abscissa
Alle origini di un tipo architettonico fra Roma, il mondo greco e il ‘laboratorio Lazio’ del tardo ellenismo
No full textIn the wake of the publication of the nymphaeum of Q. Mutius in Segni, one can retrace, on the basis of some new acquisitions and reflections, the traces that, from the Hellenistic world, and perhaps Alexandrian in particular, seem to lead to the sudden appearance in the cities of “Roman” Italy of the 2nd century BC of some architectural types linked to the monumentalization of water.
Thus, starting from Lazio and the Palestrina dossier, it seems possible to follow this process starting from the early development of the nymphaeums, a type capable of offering the clearest connections with the Greek experience. In the same period of time, the chamber nymphaeums seem to find rapid and wide diffusion, built in individual cases in precise monumental forms whose diffusion marks, like other architectural typologies, a bridge between the Latins and the foederati.
Finally, on this dual line of experience is grafted the elaboration of the type, both architectural and decorative, of the nymphaeum with a chamber with walls divided into niches and decorated with rustic mosaic, a type that finds its complete and accomplished codification in the monument signed by Q. Mutius at the end of the 2nd century BC. The elaboration of these types is a splendid example, in the architectural field and in the broader and better-known phenomenon of the renewal of urban planning during the 2nd century BC, of the process of creation of that late-Hellenistic language
that, generally thought of in a purely “dual” perspective in the dialectic between Rome and the Greek world, seems today to show a plurality of centers of elaboration. Among these, certainly, the cities of the “Lazio del Calcare” play an extremely important role, but important signs of participation are also given by various allied communities
