We address various aspects on estimating the magnetocaloric effect from magnetization measurements, and the use of a Maxwell relation in first- and second-order phase transitions, including (a) the ...use of magnetization as a thermodynamic variable in an inhomogeneous situation (structural or chemical distributions, magnetic domains) and (b) non-equilibrium conditions (irreversibility) on first-order phase transitions, including mixed-phase conditions. We find that the Maxwell equation or any other methods such as area differentiation should be used with caution and not include data out of equilibrium, which can lead to spurious results. The use of methods for modeling the magnetic entropy change of first- and second-order magnetic phase transitions, such as Landau and mean-field theory, can be helpful to better understand the nature of the commonly found anomalous peaks in magnetic entropy change and their physical relevance.
Estuarine systems receive large amounts of organic matter that enhance the production of greenhouse gases (GHGs), such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Despite ...considerable research on GHGs and dissolved organic matter (DOM) distribution in estuaries, little is known about the linkage between these gases and DOM composition. Here we evaluated the relationship between three GHGs (CO2, CH4, and N2O) and DOM composition, determined through optical properties, in Guadalete estuary (Bay of Cadiz, Spain). The partial pressure of CO2, and CH4 and N2O concentrations ranged between 332.8 and 6807.1 μatm, 19.9–6440.1 nM, and 6.8–283.9 nM, respectively. Thus, the Guadalete estuary was a source of CO2, CH4 and N2O to the atmosphere. We validated three PARAFAC components related to humic-like fluorescence from terrestrial, microbial and effluent sources, and one with protein-like material. Humic-like components accounted for 86% ± 6% of the total FDOM pool, indicating a predominantly allochthonous DOM origin. The three GHGs were significantly linked to DOC concentration and DOM composition, exhibiting different patterns in these linkages. Terrestrial and microbial humic-like substances with increasing aromaticity might enhance pCO2 in Guadalete estuary. Dissolved CH4 concentrations showed the strongest relationship with DOM composition, indicating that humic and protein-like material are linked with their distribution. In contrast, dissolved N2O was only related with the protein-like fraction and with humic-like material derived from anthropogenic activities (sewage and agriculture). Our results further indicate that a possible coupling between benthic fluxes of GHGs and DOM might be occurring in this shallow estuary. We conclude that it is important to account for DOM composition when studying GHGs distribution in estuarine systems to understand their roles and potential responses associated with climate change.
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•In estuarine systems, pCO2, CH4, and N2O distribution were linked to DOM composition.•Terrestrial and microbial humic-like material with increasing aromaticity might enhance pCO2 values.•Dissolved CH4 concentration was related with DOM derived from terrestrial, microbial, and anthropogenic sources.•Dissolved N2O was related with protein-like DOM and humic-like compounds derived from anthropogenic activities (sewage and agriculture).•In shallow estuarine systems, benthic flux of DOM and greenhouse gases may be coupled.
We assessed the state of knowledge regarding the effects of large-scale pollution with neonicotinoid insecticides and fipronil on non-target invertebrate species of terrestrial, freshwater and marine ...environments. A large section of the assessment is dedicated to the state of knowledge on sublethal effects on honeybees (Apis mellifera) because this important pollinator is the most studied non-target invertebrate species. Lepidoptera (butterflies and moths), Lumbricidae (earthworms), Apoidae sensu lato (bumblebees, solitary bees) and the section “other invertebrates” review available studies on the other terrestrial species. The sections on freshwater and marine species are rather short as little is known so far about the impact of neonicotinoid insecticides and fipronil on the diverse invertebrate fauna of these widely exposed habitats. For terrestrial and aquatic invertebrate species, the known effects of neonicotinoid pesticides and fipronil are described ranging from organismal toxicology and behavioural effects to population-level effects. For earthworms, freshwater and marine species, the relation of findings to regulatory risk assessment is described. Neonicotinoid insecticides exhibit very high toxicity to a wide range of invertebrates, particularly insects, and field-realistic exposure is likely to result in both lethal and a broad range of important sublethal impacts. There is a major knowledge gap regarding impacts on the grand majority of invertebrates, many of which perform essential roles enabling healthy ecosystem functioning. The data on the few non-target species on which field tests have been performed are limited by major flaws in the outdated test protocols. Despite large knowledge gaps and uncertainties, enough knowledge exists to conclude that existing levels of pollution with neonicotinoids and fipronil resulting from presently authorized uses frequently exceed the lowest observed adverse effect concentrations and are thus likely to have large-scale and wide ranging negative biological and ecological impacts on a wide range of non-target invertebrates in terrestrial, aquatic, marine and benthic habitats.
Self-assembled short peptide-based gels are highly promising drug delivery systems. However, implementing a stimulus often requires screening different structures to obtain gels with suitable ...properties, and drugs might not be well encapsulated and/or cause undesirable effects on the gel's properties. To overcome this challenge, a new design approach is presented to modulate the release of doxorubicin as a model chemotherapeutic drug through the interplay of (di)phenylalanine-coated magnetic nanoparticles, PEGylated liposomes and doxorubicin co-assembly in dehydropeptide-based gels. The composites enable an enhancement of the gelation kinetics in a concentration-dependent manner, mainly through the use of PEGylated liposomes. The effect of the co-assembly of phenylalanine-coated nanoparticles with the hydrogel displays a concentration and size dependence. Finally, the integration of liposomes as doxorubicin storage units and of nanoparticles as composites that co-assemble with the gel matrix enables the tuneability of both passive and active doxorubicin release through a thermal, and a low-frequency alternating magnetic field-based trigger. In addition to the modulation of the gel properties, the functionalization with (di)phenylalanine improves the cytocompatibility of the nanoparticles. Hereby, this work paves a way for the development of peptide-based supramolecular systems for on-demand and controlled release of drugs.
The potential thermal regulation effect of rigid polyurethane (RPU) foams can be enhanced by the incorporation of phase change materials (PCM). The main goal of the present work is to evaluate the ...thermal characteristics of RPU panels using two different types of PCM (a commercial one and another based on paraffin and calcium carbonate) and to quantify their potential as thermal regulators of indoor spaces.
The experimental results obtained revealed that the RPU panels incorporating PCM can lead to a thermal amplitude reduction of about 3.5–1 °C (peak maximum temperature – peak minimum temperature). Furthermore, it was demonstrated that the performance of the RPU panel with PCM was enhanced when the external and internal mean temperature were closer to the melting peak temperature of the PCM. Additionally, it was also verified that the thermal amplitude reduction due to the PCM is more significant for the RPU panel incorporating PCM.
In brief, the results showed that the efficiency of the RPU panels incorporating PCM is not exclusively dependent on the presence and quantity of PCM (equivalent in wt% in all cases) but it is also affected by the imposed temperature profile and the PCM thermal properties.
•Rigid polyurethane foams (RPU) panels incorporating phase change materials (PCM).•Commercial microencapsulated PCM versus shape stabilized CaCO3 containing-PCM.•Inclusion of PCM on RPU panels enhances the thermal regulation of indoor spaces.•Efficiency of RPU panels is not exclusively dependent on the quantity of PCM.•Thermal performance is affected by the imposed temperature and the PCM properties.
In striving for mass production of magnetocaloric materials for refrigeration applications, one has to face the fact that these will not be laboratory‐grade materials, and will necessarily present ...(at the very least) composition gradients due to lower quality precursors. One can expect some probable consequences from this, namely that the maximum value of magnetic entropy change (ΔSM) will decrease compared to a pure material, but also some broadening of the ΔSM(T) curves should occur, as observed in some elementary ferromagnets. Some theoretical work has focused on this topic, for second‐order phase transition systems via the Landau theory of phase transitions and the molecular mean‐field model. Still, these theoretical considerations do not directly apply to first‐order phase transition (giant magnetocaloric effect) systems. We here present a study on the effect of disorder on the magnetic and magnetocaloric properties of first‐order phase transition systems. We employ the Bean–Rodbell model, and consider disorder to be described by a width of a Curie temperature distribution. We show how disorder effects “smooth” the discontinuities of magnetization and entropy change, and also affect magnetic hysteresis. We show how for sufficiently large disorder, the shape of the magnetic entropy curves approximate the distribution function. We discuss how the magnetic field dependence of magnetic entropy change is affected by disorder, in light of recent reports of “second‐order like” dependence of magnetic entropy change on applied magnetic field, for disordered giant magnetocaloric effect La–Fe–Si‐based samples.
Central inverters based on conventional topologies are the current preferred solution in solar farms because of their low cost and simplicity. However, such topologies have some disadvantages such as ...poor maximum power tracking, use of bulky filters, and low-frequency transformers. An interesting alternative in this case is the SiC-based cascaded multilevel converter (CMC), which provides a distributed maximum power point tracking control with reduced footprint and high flexibility. Each cell of a CMC usually has, as an intermediate stage, a solid-state transformer based on a dual-active-bridge dc-dc converter. Due to the unidirectional power flow characteristic of the photovoltaic application and aiming at further reduction in the converter volume, this work proposes a forward dual-active-bridge (F-DAB) topology, which reduces the number of active switches. This paper shows through analytical, simulation, and experimental results that the cell using an F-DAB is superior to other unidirectional topologies in three aspects: higher power density with commercially available power modules, reduced part count, and simplicity of control.
Non-thermal food processing is configured as an interesting alternative for the food industry due to the increased nutrient retention and minimal sensory changes in processed products.
The aim of ...this review is to address the potential of supercritical carbon dioxide technology, emphasizing milk and dairy processing, including the historical aspects, main advantages, microbial inactivation mechanisms, as well as effects in some quality parameters of dairy products.
The use of supercritical carbon dioxide technology (SC-CO2) presents great potential application in dairy processing, since it is effective to reduce microbial load when compared to the pasteurization process, thus obtaining a product with greater shelf life and better organoleptic properties with minimal and sometimes positive changes in the intrinsic quality parameters.
•Supercritical Carbon Dioxide Technology is presented as nonthermal food processing.•Fundamentals and advantages and microbial inactivation mechanism are reported.•Previous studies covering the effects at the intrinsic quality parameters of dairy foods are also revised.
Coastal lagoons are among the most productive and biodiverse systems in the world and are important sentinels of climate change. The Mar Menor is one of the largest coastal lagoons in the ...Mediterranean, providing a variety of ecosystem services and resources to the community. However, in recent decades this lagoon has suffered drastic changes and degradation caused by human activities. We analyzed the concentration of dissolved organic carbon (DOC) and the optical properties of dissolved organic matter (DOM) in the water column and sediment pore water during the summer and winter of 2018 and during eighteen months from 2016 to 2018. Overall, we found that the composition of DOM is mainly related to and enhanced by anthropogenic activities and microbial metabolism. DOM enters the lagoon via urban and agricultural runoff, drainage systems, and wastewater treatment plants. Additionally, strong microbial metabolism in sediments leads to differences in DOM composition between water and sediments. In the water column, humic-like components accounted for 71 % of the total DOM, while protein-like compounds were most abundant in sediment pore water. We observed a strong seasonal variability associated with precipitation and the system collapse in 2016 (phytoplankton bloom), which resulted in the death of 80 % of macrophytes. The sediments act as a source of DOM to the overlying water, likely due to relatively high organic matter content and intense microbial activity, primarily through anaerobic pathways. Benthic fluxes of DOC ranged from 5.24 to 33.30 mmol m−2 d−1, being higher in winter than summer 2018 and decreasing from north to south, likely related to lower residence time in the northern basin, groundwater discharge and accumulation of organic matter from the dead meadows. We estimate a net flux of DOC from the Mar Menor toward the Mediterranean Sea of 1.57 × 107 mol yr−1.
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•DOM composition was mainly associated and/or enhanced by anthropogenic activities.•DOM distribution showed a strong seasonal variability related with precipitations and the break down of the system in 2016.•The sediments of the lagoon acted as a source of DOM to the overlying waters.•There is a net flux of DOC from de Mar Menor toward the Mediterranean Sea.•DOM characteristics reflect the anthropogenic impact that this lagoon is suffering.
In this work, n-type a-Si:H/c-Si heterojunction solar cells were fabricated using mono-like silicon wafers. First, cell efficiency distribution was investigated along a complete mono-like silicon ...ingot. Advanced electrical characterization was performed in order to understand limiting mechanisms of the final device performances. Fabricated heterojunction cells with the standard industrial compatible process have demonstrated efficiencies comparable to those with our Czochralski grown monocrystalline substrates: over 19% along a large part of the ingot. Moreover, the best wafers were evaluated using our advanced cells process. Very high efficiencies over 21.5% have been obtained, demonstrating the potential of such substrates for very high efficiency solar cells.
•Heterojunction silicon solar cells have been fabricated on mono-like silicon wafers.•Mono-like silicon ingot has been studied all along its height.•We performed advanced electrical characterizations on mono-like silicon.•We obtained high efficiency with an advanced solar cell process.
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