1,720,976 research outputs found
Heat and mass transfer in porous materials for passive energy-conversion devices
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
Selective Ammonium Recovery from Livestock and Organic Solid Waste Digestates Using Zeolite Tuff: Efficiency and Farm-Scale Prospects
No full textImplementing efficient strategies for the circular recovery and reuse of nutrients from wastewaters is mandatory to meet the Green Deal objectives and Sustainable Development Goals. In this context we investigated the use of zeolitic tuff (containing chabazite and phillipsite) in the selective recovery and reuse of N from various anaerobic liquid digestates in view of their implementation in farm-scale treatment plants. We tested the method on three livestock digestates and two municipal organic solid waste digestates. Adsorption isotherms and kinetics were assessed on each digestate, and a large set of parameters, including (i) contact time, (ii) initial NH4+ concentration, (iii) presence of competing ions, (iv) total solids content, and (vi) separation methods (microfiltration and clarification), were considered in the experimental design. Our results showed that the adsorption mechanism can be explained by the Freundlich model (R2 up to 0.97), indicating a multilayer and heterogeneous adsorption, while the kinetic of adsorption can be explained by the pseudo-second-order model, indicating chemical adsorption and ion exchange. The efficiency in the removal of NH4+ was indirectly related to the K+ and total solids content of the digestate. Maximum NH4+ removal exceeded 90% in MSW-derived digestates and 80% within 60 min in livestock-derived digestates at a 5% solid/liquid ratio. Thermodynamic parameters confirmed favorable and spontaneous adsorption (ΔG up to −7 kJ⋅mol−1). Farm-scale projections estimate a nitrogen recovery potential of 1.2 to 16 kg N⋅day−1, depending on digestate type and process conditions. These findings support the application of natural zeolitic tuffs as a low-cost, chemical-free solution for ammonium recovery, contributing to sustainable agriculture and circular economy objectives
Enhanced latent thermal energy battery with additive manufacturing
Full text linkThe low thermal conductivity of Phase Change Materials (PCMs), such as paraffin waxes, hinders efficient latent heat storage, especially for rapid charging and discharging cycles. To address this issue, this study explores experimentally and numerically the use of metal additive manufacturing to create a latent heat storage system operating at medium temperatures (around 90°C). A 3D Cartesian metal lattice is manufactured through laser powder bed fusion to optimize heat conduction within the PCM. Experimental tests show impressive specific power densities (approximately 714 ± 17 W kg−1 during charging and 1310 ± 48 W kg−1 during discharging). Moreover, the device exhibits stability over multiple cycles. Finally, the validated finite-element model has the potential to provides a basis for general design guidelines to boost the system's performance further. Potential applications of this technology are highlighted in the automotive industry, where such systems could efficiently manage thermal energy, for instance, by capturing excess heat from an engine's cooling radiator to expedite the warm-up process during a cold start, which is a critical phase for reducing pollutant emissions
Assessment of Nitrogen Dynamics in an Acidic Sandy-Loam Soil: Impact of Varied Nitrogen Sources and Incorporation of Chabazite Zeolite Tuff
No full textVolcanic tuffs containing high percentage of zeolites have been extensively studied, both in their natural state or enriched with nitrogen, as a means of enhancing soil properties and fertilizer efficiency. Limited data however exist on their application in acidic sandy soils and in conjunction with organic fertilizers.
This work consists of a 50-day laboratory incubation study wherein the nitrogen dynamics in an acidic sandy-loam agricultural soil fertilized with various nitrogen sources were investigated. These sources included urea, nitrogen-enriched chabazite zeolite tuff, and pelleted composted manure. Additionally, the nitrogen sources were tested in combination with the addition of chabazite zeolite tuff in its natural state to act as a soil improver.
The results revealed distinct behaviors among the various nitrogen sources, particularly affecting soil pH and nitrogen dynamics. Mineralization was very slow in manure-fertilized soil, whereas nitrogen-enriched zeolite exhibited a more balanced behavior in terms of net nitrate production and ammonium consumption. Nitrogen-enriched zeolite and urea demonstrated a temporary "liming" effect, while pelleted manure promoted a prolonged shift of soil pH toward neutral values.
In conclusion, nitrogen-charged chabazite zeolite tuff proved to be a valuable nitrogen source in acidic sandy-loam soil, serving as a viable alternative to synthetic fertilizers and an effective means of nitrogen recycling
Innovative Solutions for Reducing Copper-Based Pesticides in Sustainable Agriculture: The LIFE MICROFIGHTER Project
No full textCopper (Cu) is one of the seven essential micronutrients for plants, but its intensive use as a
pesticide in agriculture, especially in organic and integrated production systems, has led to its
progressive accumulation in European soils. This phenomenon poses a serious threat to soil
biodiversity, water quality, and human health. Despite EU regulations limiting copper inputs to a
maximum of 28 kg/ha over seven years (an average of 4 kg/ha/year), a significant amount of
copper-based pesticides is still widely used, as they remain essential for controlling numerous
fungal and bacterial diseases. However, their accumulation in soils and sediments has become an
unsustainable environmental issue, particularly in Italy, Greece, France, and Spain, where
agricultural land contamination is particularly high. The LIFE MICROFIGHTER project proposes an
innovative solution to reduce or replace copper-based pesticides by demonstrating the efficacy of
a new Zeo-Biopesticide, applied as a foliar treatment, composed of natural Italian zeolites
(potassium chabazite) and a specific biocontrol microorganism (Pseudomonas sp. DLS65). The goal
is to control major pathogens of grapevine, tomato, and olive (including downy mildew, bacterial
speck, bacterial spot, olive knot, and peacock spot), exploiting Zeo-Biopesticide and hence
reducing or avoiding the use of copper in organic and integrated agricultural systems. The efficacy
of the method will be demonstrated with field trials (2-3 years duration) in Italy, Croatia, and Spain
(a total of 9 fields).
The specific objectives of the project includes: i) reducing copper inputs in agricultural soils from
an average of 4 kg/ha/year to 2 kg/ha/year without compromising crop yield and quality, with the
potential for complete copper replacement; ii) demonstrating a reduction in total soil copper
concentration while promoting increased soil biodiversity; iii) raising awareness among farmers,
policymakers, and other stakeholders about the environmental and health risks associated with
copper-based pesticides, and promoting the adoption of the Zeo-Biopesticide as an effective and
sustainable alternative; iv) conducting environmental monitoring campaigns, life cycle analysis
(LCA), and developing a business plan to assess the economic and environmental sustainability of
the new technology
Multistage and passive cooling process driven by salinity difference
Full text linkSpace cooling in buildings is anticipated to rise because of an increasing thermal comfort demand worldwide, and this calls for cost-effective and sustainable cooling technologies. We present a proof-of-concept multistage device, where a net cooling capacity and a temperature difference are demonstrated as long as two water solutions at disparate salinity are maintained. Each stage is made of two hydrophilic layers separated by a hydrophobic membrane. An imbalance in water activity in the two layers naturally causes a non-isothermal vapor flux across the membrane without requiring any mechanical ancillaries. One prototype of the device developed a specific cooling capacity of up to 170 W m−2 at a vanishing temperature difference, considering a 3.1 mol/kg calcium chloride solution. To provide perspective, if successfully up-scaled, this concept may help satisfy at least partially the cooling needs in hot, humid regions with naturally available salinity gradients
3D printed lattice metal structures for enhanced heat transfer in latent heat storage systems
Full text linkThe low thermal conductivity of Phase Change Materials (PCMs), e.g., paraffin waxes, is one of the main drawbacks of latent heat storage, especially when fast charging and discharging cycles are required. The introduction of highly conductive fillers in the PCM matrix may be an effective solution; however, it is difficult to grant their stable and homogeneous dispersion, which therefore limits the resulting enhancement of the overall thermal conductivity. Metal 3D printing or additive manufacturing, instead, allows to manufacture complex geometries with precise patterns, therefore allowing the design of optimal paths for heat conduction within the PCM. In this work, a device-scale latent heat storage system operating at medium temperatures (∼ 90 °C) was manufactured and characterized. Its innovative design relies on a 3D Cartesian metal lattice, fabricated via laser powder bed fusion, to achieve higher specific power densities. Numerical and experimental tests demonstrated remarkable specific power (approximately 714 ± 17 W kg−1 and 1310 ± 48 W kg−1 during heat charge and discharge, respectively). Moreover, the device performance remained stable over multiple charging and discharging cycles. Finally, simulation results were used to infer general design guidelines to further enhance the device performance. This work aims at promoting the use of metal additive manufacturing to design efficient and responsive thermal energy storage units for medium-sized applications, such as in the automotive sector (e.g. speed up of the engine warm up or as an auxiliary for other enhanced thermal management strategies
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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