Evidence of a structural anomaly at 14 K in polymerised CsC60

We report the results of a high-resolution synchrotron X-ray powder diffraction study of polymerised CsC$_{60}$ in the temperature range 4 to 40 K. Its crystal structure is monoclinic (space group I2/m), isostructural with RbC$_{60}$. Below 14 K, a spontaneous thermal contraction is observed along both the polymer chain axis, $a$ and the interchain separation along [111], $d_1$. This structural anomaly could trigger the occurrence of the spin-singlet ground state, observed by NMR at the same temperature.Comment: 8 pages, 5 figures, submitte

A multi-stage model for dielectric barrier discharge in atmospheric pressure air

In this paper, a multi-stage numerical methodology for the description of the Dielectric Barrier Discharge physics in air is discussed. The behavior of the heavy species is computed using drift-diffusion equations. Electrons are taken into account by solving a non-linear formulation of electrostatics. The physical effects of the steamer discharges are modelled by means of a simplified 0D approach. The model also includes a semi-implicit 0D model for the assessment of the elementary chemical processes occurring in air. The developed methodology is employed for the simulation of a volumetric Dielectric Barrier Discharge reactor. The obtained species number density and surface charge deposition rates and are shown and discussed

Increase in airborne allergenic pollen in Trentino (North Italy) over a 30-year period (1989-2018) is connected to temperature rise

The aim of this study is to verify if changes occurred in the seasonality and yearly amounts of airborne pollen in San Michele all’Adige - Northern Italy, and to evaluate their relation with climate change-related variables, such as air temperatures and frost days in the period 1989 - 2018. The study of airborne pollen and its spatio-temporal changes is highly important due to the allergenicity of many pollen taxa. The pollen allergy, in fact, interests 25-40% of population, globally, and displays an increasing trend. Climate change may impact pollen allergenicity and production, as well as plant distribution, with the potential spread of neophytes that produce allergenic pollen. The main hypothesis of our research is that climate change impacting our study area influences pollen dispersal in the atmosphere, and therefore on human-health related issues. Airborne pollen was collected using a volumetric Hirst-type aerobiological sampler (Lanzoni VPPS 2000), and the daily concentration of airborne pollen (P*m-3 ) was calculated for a total of 24 arboreal (AP; trees and shrubs) and non-arboreal pollen taxa (NAP; herbaceous) over a 30- year period. The sampling and analysis of airborne pollen have been performed in accordance with the UNI EN 16868:2019 European standard procedure. The main pollen season (MPS) descriptors were calculated for each taxon. The presence of a monotonic upward or downward temporal trend in pollen season descriptors was verified (non-parametric Mann-Kendall test) and changes were analyzed in relation to air temperature, precipitation, and land use; in addition, pollen data were analyzed clustered into three decadic blocks (non-parametric Kruskal-Wallis ANOVA) to minimize interannual fluctuations and maximize relevant change signals. The major change observed during the study period was the significant increase in annual pollen integral (APIn). This change is strongly emphasized when analyzing the pollen data in three decadic blocks, both for all the considered taxa (+58%) and for Arboreal Pollen (AP; +155%). When considering single taxa, APIn shows a significant positive trend for Cupressaceae/Taxaceae, Ulmus, Populus, Salix, Ostrya, Quercus, Olea, Plantago, Cannabaceae, and Ambrosia; a significantly earlier start of the MPS is proved for Rumex and Poaceae. Cumulated APIn shows a significant positive correlation with annual T min (<0.005) and T mean (<0.001), both of which showing a significant increase, and a negative correlation (<0.025) with the number of frost days. The research demonstrates an increasingly larger amount of airborne pollen connected to climate change, such as rising temperatures and milder winter conditions in the study area, leading to a major threat to people suffering of pollen allergies

Real Time Power Control in a High Voltage Power Supply for Dielectric Barrier Discharge Reactors: Implementation Strategy and Load Thermal Analysis

Atmospheric-pressure plasma treatments for industrial and biomedical applications are often performed using Dielectric Barrier Discharge reactors. Dedicated power supplies are needed to provide the high voltage frequency waveforms to operate these nonlinear and time-dependent loads. Moreover, there is a growing technical need for reliable and reproducible treatments, which require the discharge parameters to be actively controlled. In this work, we illustrate a low-cost power supply topology based on a push-pull converter. We perform experimental measurements on two different reactor topologies (surface and volumetric), showing that open loop operation of the power supply leads to a temperature and average power increase over time. The temperature increases by Delta T-vol similar to 120 degrees C and Delta T-sup similar to 70 degrees C, while the power increases by Delta P-vol similar to 78% and Delta P-sup similar to 60% for the volumetric (40 s) and superficial reactors (120 s), respectively. We discuss how these changes are often unwanted in practical applications. A simplified circuital model of the power supply-reactor system is used to infer the physical relation between the observed reactor thermal behavior and its electrical characteristics. We then show a control strategy for the power supply voltage to ensure constant average power operation of the device based on real-time power measurements on the high voltage side of the power supply and an empirical expression relating the delivered power to the power supply output voltage. These are performed with an Arduino Due microcontroller unit, also used to control the power supply. In a controlled operation the measured power stays within 5% of the reference value for both configurations, reducing the temperature increments to Delta T-vol similar to 80 degrees C and Delta T-sup similar to 44 degrees C, respectively. The obtained results show that the proposed novel control strategy is capable of following the transient temperature behavior, achieving a constant average power operation and subsequently limiting the reactor thermal stress

Forests attenuate temperature and air pollution discomfort in montane tourist areas

Forests deliver many ecosystem services, from provisioning to regulating and cultural services. We aimed at demonstrating microclimatic regulation and pollutant removal as especially relevant ecosystem services when considering the tourism vocation of the Alpine regions. A study was realized along an altitudinal gradient (900–1600 m a.s.l.) in Trentino, northern Italy, an area with high touristic presence (ca. 9.3 million overnight stays in summer 2021). Nitrogen dioxide (NO2 , µg m−3 ), ozone (O3 , µg m−3 ) concentrations, air temperature (T, ◦C), and relative humidity (RH, %) were simultaneously measured in three open-field sites (OF) and below-canopy Norway spruce forest stands (FO) during the period 23 May–7 August 2013. The temperature–humidity index (THI) was calculated. We found a distinct mitigating effect of forest on T, with lower maximum (−30.6%) and higher minimum values (+6.3%) in FO than in OF. THI supported a higher comfort sensation in FO than in OF, especially in the central part of the day. NO2 concentrations did not differ between OF and FO; ozone concentrations were lower in FO than OF. This study confirms the role of forests in providing several ecosystem services beneficial for forest users, especially relevant for promoting nature-based tourism in the Alpine regio

Analytical Model of the Anisotropic Dimensional Change on Sintering of Ferrous PM Parts

Abstract This work proposes an analytical model developed from experimental data to describe the anisotropic dimensional change on sintering. Axial-symmetric iron parts differing for geometry and sintering conditions have been investigated, aiming at highlighting the influence of geometry. The specimens were measured in the green and sintered state by a coordinate measuring machine (CMM). The dimensional changes of height, external diameter and internal diameter were derived from measurement results. The anisotropy of the dimensional variations has been studied with reference to the isotropic dimensional change derived from the change in volume of the parts. The influence of geometry and sintering temperature was highlighted. To properly describe the dimensional variations in the compaction plane, the dimensional change of the external diameter versus the dimensional change of the internal one has been analysed. By means of the experimental data, a reliable analytical relationship has been found, dependent on the parts geometry. An anisotropy parameter has been identified, which allows relating the dimensional change in the compaction plane and in the axial direction to the isotropic dimensional change. This parameter depends both on geometry and on sintering conditions. By means of the anisotropy parameter an analytical model for the anisotropic behaviour has been developed

Aerobiology in alpine environments: exploring pollen biodiversity and its impacts on human health

This review summarizes methods and relevant outcomes of aerobiological studies carried out in the alpine biome worldwide impacting the knowledge on the occurrence of airborne pollen and their origin, for biodiversity studies, models of transport, forecasts, and climate change scenarios, for the reconstruction of past vegetation, and the potential impacts on human health. Deposition sampling is the method of choice, while volumetric sampling is mostly performed in densely populated mountain ranges. Conventional microscopic identification of pollen of alpine environments is rarely complemented or replaced by molecular methods. The pollen bioaerosol mirrors the surrounding vegetation but includes components from medium and distant source locations. However, there is no uniform understanding on the definition of source-scales – crucial for the interpretation of the bioaerosol constituents – to which we propose an answer. Alpine habitats, with their cold-adapted plant communities, may react to increasing temperatures with shifts in their range. The potential of using pollen as a proxy to monitor such changes in alpine biomes has been exploited in paleoecology but rarely in aerobiology. Health impacts are linked to the low allergen load in the bioaerosol and the overall effect of the alpine climate in a highly natural environment. Generally, the soothing effect is reported for respiratory allergy patients, which may be jeopardized by seasonality and allergens transported from outside. The complex topography of mountain ranges does not allow for general assumptions on the quality and quantity of bioaerosol in alpine environments. We emphasize the importance of monitoring the bioaerosol in alpine environments to evaluate the effects of global change, and to optimize the management of respiratory health issue

Increase in airborne allergenic pollen in Trentino (North Italy): knowledge to adapt to climate change

Pollen allergy affects approximately 25% of adult and 40% of children globally (Nur Husna et al. 2022). Climate change is impacting allergenicity and pollen production, as well as the spread of neophytes that produce allergenic pollen, due to the combined effects of milder weather, air pollution, and elevated CO2 levels (Luschkova et al. 2022). As a result, there is an upward trend in allergic diseases (D’Amato et al. 2015). The study of pollen and its spatio-temporal changes is highly important due to the allergenicity of many airborne pollen taxa. Earlier-onset of pollen, the lengthening of the pollen season, and/or the increase in pollen quantities, can diminish the quality of life of allergic patients. In the "one health" perspective, we examine how climate change impact the ecosystem, affecting human well-being and health. Phenology, the science of natural recurring events, is one of the preferred indicators for observing the impacts of climate change on ecosystems and biological processes (Parmesan 2006). The shift in phenology is a high-temporal resolution signal of this impact and pollen dispersal is often used as a reliable proxy of flowering. This study describes the significant changes that have occurred to the airborne pollen component recorded in San Michele all’Adige, Northern Italy, from 1989 to 2018, analyzing a total of 24 arboreal (AP; trees and shrubs) and non-arboreal pollen taxa (NAP; herbaceous). Airborne pollen was collected using a volumetric Hirst-type aerobiological sampler (Lanzoni VPPS 2000), and the daily concentration of airborne pollen (P*m-3) was calculated for each taxon over a 30-year period from 1989 to 2018. The sampling and analysis of airborne pollen have been performed in accordance with the UNI EN 16868:2019 European standard procedure. The following pollen season descriptors were calculated for each taxon: (i) annual pollen integral (APIn; pollen*day*m-3); (ii) the start and end dates of the main pollen season (MPS), as the day of the year (DOY) when 2.5% and 97.5% of the APIn was reached, respectively; (iii) the length of the MPS, as the difference between the end and start DOY (+1); (iv) peak concentration; and (v) peak date, as the DOY when the maximum concentration was registered. The presence of a monotonic upward or downward temporal trend in pollen season descriptors was verified and changes were analyzed in relation to temperature, precipitation, and land use; in addition, pollen data were analyzed clustered into blocks of one decade each to minimize interannual fluctuations and maximize relevant change signals. The major result is an increase in pollen load (Fig. 1). All arboreal and shrub species (AP) and the majority of herbaceous (NAP) species had an impressive increase in pollen quantities. The extent of the increase in pollen load is evident when analyzing decadic blocks, with a relevant increase in the APIn for the total pollen spectrum, mostly due to AP taxa, with hop hornbeam and cypress family accounting for 49% of the increase (average on the 30-year period). Accordingly, AP shows a significant increase (+31 days) in the number of days with high pollen concentrations (i.e., > 100 pollen grains/m3). Such an increase in pollen quantity is unlikely to be related to changes in land use, given that the increase in forests and semi-natural areas is limited. The finding of an increase in APIn, especially marked for AP taxa, is consistent with previous studies and on a broader scale, from Europe (Ziello et al. 2012) to the entire Northern Hemisphere (Ziska et al. 2019). Moreover, some evidence of early start date for some taxa has been observed (e.g. Poaceae), at the same time as a longer pollen seasons for other taxa (e.g. Cupressaceae). A larger amount of pollen, an increase in the number of days with high pollen concentration, and an early start to the pollen season, which have been occurring since 1990 in the study area, all constitute a worsening situation and a major threat to people with pollen allergies. Thanks to these achievements it is possible to develop proposals for adaptation strategies that include as early stages: (i) development and implementation of risk communication strategies, (ii) implementation of good practices for green management. These proposals will be included in the Climate Change Adaptation Strategy of the Autonomous Province of Trento, which is currently being defined. Figures Fig 1: Increase of total arboreal pollen integral in the 30 years; detail for Ostrya (hop hornbeam) pollen taxonom

Assessment of AC Corrosion Probability in Buried Pipelines with a FEM-Assisted Stochastic Approach

In this paper, a stochastic approach is combined with field theory and circuit methods to study how the geometrical and electrical properties of holidays (defects or pores in the insulating coating) in a metallic pipeline influence the probability of exceeding the current density limit for corrosion. Three-dimensional FEM simulations are conducted to assess the influence of the shape and electrical resistivity of the pore on the computed spread resistance value. The obtained results are then used to evaluate the probability of exceeding a given current density value for different sizes of pore and soil resistivities. Finally, a case of 50 Hz interference along a pipeline-transmission line routing is examined. The probabilistic approach presented in this paper allows the pipeline sections more subjected to the induced AC corrosion risk to be identified to be used as an auxiliary tool for adopting preventive protection countermeasures. Lastly, unlike most papers devoted to assessing electromagnetic interference on pipelines, the present work uses a probabilistic rather than a deterministic approach, representing its main novelty aspect

FLARE: A Framework for the Finite Element Simulation of Electromagnetic Interference on Buried Metallic Pipelines

The functionality of buried metallic pipelines can be compromised by the electrical lines that share the same right-of-way. Given the considerable size of shared corridors, computer simulation is an important tool for performing risk assessment and mitigation design. In this work, we introduce an open-source computational framework for the analysis of electromagnetic interference on large earth-return structures. The developed framework is based on FLARE-an efficient finite element solver developed by the authors in MATLAB((R)). FLARE includes solvers for problems involving static electric and magnetic fields, and DC and time-harmonic AC currents. Quasi-magnetostatic transient problems can be studied through time-marching or-for linear problems-with an efficient inverse-Laplace approach. In this work, we succinctly describe the optimization of time-critical operations in FLARE, as well as the implementation of a transient solver with automatic time-stepping. We validate the numerical results obtained with FLARE via a comparison with the commercial software COMSOL Multiphysics((R)). We then use the validated time-marching analysis results to test the accuracy and efficiency of three numerical inverse-Laplace algorithms. The test problem considered is the assessment of the inductive coupling between a 500 kV transmission line and a metallic pipeline buried in the soil