Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 83
Filtrar
1.
Inorg Chem ; 63(27): 12641-12650, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38920333

RESUMO

Metal halide perovskites with a two-dimensional structure are utilized in photovoltaics and optoelectronics. High-crystallinity CsSn2Br5 specimens have been synthesized via ball milling. Differential scanning calorimetry curves show melting at 553 K (endothermic) and recrystallization at 516 K (exothermic). Structural analysis using synchrotron X-ray diffraction data, collected from 100 to 373 K, allows for the determination of Debye model parameters. This analysis provides insights into the relative Cs-Br and Sn-Br chemical bonds within the tetragonal structure (space group: I4/mcm), which remains stable throughout the temperature range studied. Combined with neutron data, X-N techniques permit the identification of the Sn2+ lone electron pair (5s2) in the two-dimensional framework, occupying empty space opposite to the four Sn-Br bonds of the pyramidal [SnBr4] coordination polyhedra. Additionally, diffuse reflectance UV-vis spectroscopy unveils an indirect optical gap of approximately ∼3.3 eV, aligning with the calculated value from the B3LYP-DFT method (∼3.2 eV). The material exhibits a positive Seebeck coefficient as high as 6.5 × 104 µV K-1 at 350 K, which evolves down to negative values of -3.0 × 103 µV K-1 at 550 K, surpassing values reported for other halide perovskites. Notably, the thermal conductivity remains exceptionally low, between 0.32 and 0.25 W m-1 K-1.

2.
ACS Appl Mater Interfaces ; 16(14): 17474-17482, 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38563237

RESUMO

A new anode material, Ru-SrMo0.9O3-δ, with a perovskite structure and segregated metallic Ru, has been tested in an intermediate-temperature solid oxide fuel cell (IT-SOFC) in an electrolyte-supported configuration giving substantial power densities as high as 840 mW/cm2 at 850 °C using pure H2 as fuel. This material has been prepared by the citrate method and structurally and microstructurally characterized at room temperature by different techniques such as X-ray diffraction (XRD), neutron powder diffraction (NPD), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM). NPD was very useful to determine oxygen positions and vacancies, unveiling a cubic and oxygen-deficient perovskite SrMo0.9O3-δ oxide with a Pm-3m space group and potential ionic mobility. On the other hand, SEM and STEM studies have allowed to identify metallic segregated Ru nanoparticles providing the material with an excellent catalytic activity. Other properties such as the thermal expansion coefficient (TEC) and chemical compatibility with other cell components or electrical conductivity have also been studied to understand the excellent performance of this material as anode in IT-SOFC and correlate it with the crystallographic structure.

3.
Fish Physiol Biochem ; 50(2): 463-475, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38060080

RESUMO

This study investigated the effects of occupational enrichment, specifically underwater currents, on the stress status of rainbow trout (Oncorhynchus mykiss). A total of 540 fish were divided into three groups: control tanks without artificial currents (CO), tanks with randomly fired underwater currents (RFC), and tanks with continuous current throughout the day (CT). After 30 days, half of the fish in each group underwent a 5-day pre-slaughter fasting (5D), while the others were fed until the day before slaughter (0D). Fish in the RFC group exhibited lower levels of plasma cortisol and acetylcholinesterase enzyme activity in hypothalamus and optic tract than other groups, suggesting an improved stress status. RFC group also showed higher levels of non-esterified fatty acids (NEFA) in 5D fish and higher liver glycogen stores, suggesting improved energy reserves. In comparison, the CT group had higher LDH levels, possibly due to their increased swimming activity. The CO group had significantly lower NEFA levels at 5D compared to the RFC group, suggesting lower energy reserves. The RFC fish had darker and yellow-reddish skin and liver color, suggesting an improved stress status and lower lipid reserves, respectively. Overall, although a significant stress response was not observed in fasted individuals, possibly due to the relatively short fasting period, the study suggests that providing occupational enrichment using randomly fired underwater currents for 1 month helped to improve stress status in rainbow trout, indicating that occupational enrichment during the grow-out phase can positively impact the welfare of rainbow trout during routine handling procedures.


Assuntos
Oncorhynchus mykiss , Animais , Oncorhynchus mykiss/fisiologia , Ácidos Graxos não Esterificados/farmacologia , Acetilcolinesterase , Fígado , Jejum/fisiologia
4.
J Sci Food Agric ; 104(6): 3487-3497, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38133882

RESUMO

BACKGROUND: Some environmental enrichment methods, such as occupational enrichment (OE), can improve fish growth, but little is known about its effects on fillet quality. In this study, we evaluated the effects of OE using underwater currents on different aspects of fillet quality and muscle metabolism in rainbow trout (Oncorhynchus mykiss), before and after a handling procedure (fasting). The trout were placed in groups of 30 in separate tanks in three treatments for 30 days: no artificial currents (CON), randomly fired underwater currents (RFC), and continuous underwater currents (CUC). Additionally, half of the individuals in each treatment were fasted (5 days, 45.2 °C days). RESULTS: Slaughter weight, condition factor, and relative growth were lower in CON fish, indicating a positive effect of OE on growth. Rigor mortis, muscle pH, and muscle glycogen levels were similar among treatments, indicating no effect of OE on classical measures of fillet quality. However, significant differences were found regarding fillet colour and muscle enzymes. The fillets of RFC fish were more salmon-pink in colour, which is favoured by consumers. Also, activity levels of pyruvate kinase and glycogen phosphorylase in muscle were significantly higher in CUC fish, probably due to increased energy demands, as pumps were on continually in that treatment. CONCLUSION: Overall, RFC fish seemed to have received enough stimulation to improve growth while not being excessive in terms of exhausting the animals (avoiding negative effects on muscle metabolism), whereas OE may have provided a hormetic effect, allowing fish to better adjust to fasting. © 2023 Society of Chemical Industry.


Assuntos
Oncorhynchus mykiss , Animais , Oncorhynchus mykiss/metabolismo , Alimentos Marinhos/análise , Rigor Mortis
5.
ACS Appl Mater Interfaces ; 15(34): 40762-40771, 2023 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-37595125

RESUMO

Despite the great success of hybrid CH3NH3PbI3 perovskite in photovoltaics, ascribed to its excellent optical absorption properties, its instability toward moisture is still an insurmountable drawback. All-inorganic perovskites are much less sensitive to humidity and have potential interest for solar cell applications. Alternative strategies have been developed to design novel materials with appealing properties, which include different topologies for the octahedral arrangements from three-dimensional (3D, e.g., CsPbBr3 perovskite) or two-dimensional (2D, e.g., CsPb2Br5) to zero-dimensional (0D, i.e., without connection between octahedra), as the case of Cs4PbX6 (X = Br, I) halides. The crystal structure of these materials is complex, and their thermal evolution is unexplored. In this work, we describe the synthesis of Cs4PbBr6-xIx (x = 0, 2, 4, 6) halides by mechanochemical procedures with green credentials; these specimens display excellent crystallinity enabling a detailed structural investigation from synchrotron X-ray powder diffraction (SXRD) data, essential to revisit some features in the temperature range of 90-298 K. In all this regime, the structure is defined in the trigonal R3̅c space group (#167). The presence of Cs and X vacancies suggests some ionic mobility into the crystal structure of these 0D halides. Bond valence maps (BVMs) are useful in determining isovalent surfaces for both Cs4PbBr6 and Cs4PbI6 phases, unveiling the likely ionic pathways for cesium and bromide ions and showing a full 3D connection in the bromide phase, in contrast to the iodide one. On the other hand, the evolution of the anisotropic displacement parameters is useful to evaluate the Debye temperatures, confirming that Cs atoms have more freedom to move, while Pb is more confined at its site, likely due to a higher covalency degree in Pb-X bonds than that in Cs-X bonds. Diffuse reflectance ultraviolet-visible (UV-vis) spectroscopy shows that the optical band gap can be tuned depending on iodine content (x) in the range of 3.6-3.06 eV. From density functional theory (DFT) simulations, the general trend of reducing the band gap when Br is replaced by I is well reproduced.

6.
Nanomaterials (Basel) ; 13(14)2023 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-37513065

RESUMO

This article focuses on the Na2O-Ga2O3-TiO2 system, which is barely explored in the study of transparent conductive oxides (TCOs). NaxGa4+xTin-4-xO2n-2 (n = 5, 6, and 7 and x ≈ 0.7-0.8) materials were characterized using neutron powder diffraction and aberration-corrected scanning transmission electron microscopy. Activation energy, as a function of different structures depending on tunnel size, shows a significant improvement in Na+ ion conduction from hexagonal to octagonal tunnels. New insights into the relationship between the crystal structure and the transport properties of TCOs, which are crucial for the design and development of new optoelectronic devices, are provided.

7.
J Environ Manage ; 334: 117438, 2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-36796190

RESUMO

The European Union has identified the Textile and Clothing industry as one of the essential objectives towards carbon neutrality in 2050 in line with the "European Green Deal". There are no previous research papers focused on analysing the drivers and inhibitors of the past greenhouse gas emission changes of the textile and clothing industry in Europe. This paper aims to analyse the determinants of the changes in these emissions, and the disassociation level between emissions and economic growth, throughout the 27 Member States of the European Union, from 2008 to 2018. A Logarithmic Mean Divisia Index that explains the key drivers of the changes in greenhouse gas emissions of European Union Textile and Cloth industry and a Decoupling Index have been applied. The results generally conclude that the intensity and carbonisation effects are key factors that contribute to reducing greenhouse gas emissions. The lower relative weight of the textile and clothing industry throughout the EU-27 was noteworthy, and favours lower emissions, partially counteracted by the activity effect. Also, most Member States have been decoupling the industry's emissions from economic growth. Our policy recommendation shows that if further reductions in greenhouse gas emissions are to be achieved, energy efficiency improvements and cleaner use of energy sources would offset the potential increase in emissions of this industry as a result of a relative increase in its gross value added.


Assuntos
Gases de Efeito Estufa , Gases de Efeito Estufa/análise , Dióxido de Carbono/análise , Indústrias , Desenvolvimento Econômico , Carbono/análise , Vestuário , China
8.
An. R. Acad. Nac. Farm. (Internet) ; 88(número extraordinario): 447-457, diciembre 2022.
Artigo em Espanhol | IBECS | ID: ibc-225716

RESUMO

Un escape de gas, un tren aproximándose, la cercanía de un fuego, una comida en mal estado o, sin ponerse en lo peor, una simple caricia o el saborear un buen vino, es cuestión de cómo percibimos el mundo físico a través de las percepciones sensoriales y como construimos una imagen en nuestro cerebro y su estudio ha fascinado a la humanidad a lo largo de milenios. Esta búsqueda y los hitos generados han sido galardonados con varios Premios Nobel y ha culminado en el Premio Nobel de medicina de 2021 que ha sido concedido a los norteamericanos David Julius, un bioquímico, profesor de la Universidad de California y Ardem Patapoutian, un biólogo molecular de origen armenio y nacido en Líbano, también investigador de la Universidad de California en La Jolla, por sus hallazgos acerca de los receptores de temperatura y tacto. Los revolucionarios descubrimientos de los canales iónicos TRPV1, TRPM8 y PIEZO realizados por los premiados han permitido comprender las bases moleculares de la percepción del calor, el frío, el dolor, las fuerzas mecánicas y la posición de nuestro cuerpo en el espacio, y como esas sensaciones de naturaleza tan variada se transforman en impulsos nerviosos en el SNC lo que nos permite generar una representación interna del mundo que nos rodea y adaptarnos a él. (AU)


A gas leak, an approaching train, the proximity of a fire, a rotten meal or simply a caress or tasting a good wine, it is a question of how we perceive the physical world through sensory perceptions and how we build an image in our brain and its study has fascinated mankind for millennia. These questions and the milestones generated have been awarded several Nobel Prizes and has culminated in the 2021 Nobel Prize in Medicine that has been awarded to the North Americans David Julius, a biochemist, professor at the University of California and Ardem Patapoutian, a molecular biologist of Armenian origin and born in Lebanon, also a researcher at the University of California, La Jolla, for their findings about temperature and touch receptors. The groundbreaking discoveries of the TRPV1, TRPM8 and PIEZO ion channels made by the laureates have provided insight into the molecular basis of the perception of heat, cold, pain, mechanical forces, and the position of our body in space, and how these sensations of such a varied nature are transformed into nerve impulses in the CNS that allow us to generate an internal representation of the world around us and adapt to it. (AU)


Assuntos
Humanos , Sensação Térmica , Propriocepção , Nociceptividade , Epidemias
9.
Nanomaterials (Basel) ; 12(21)2022 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-36364685

RESUMO

AgSbTe2 intermetallic compound is a promising thermoelectric material. It has also been described as necessary to obtain LAST and TAGS alloys, some of the best performing thermoelectrics of the last decades. Due to the random location of Ag and Sb atoms in the crystal structure, the electronic structure is highly influenced by the atomic ordering of these atoms and makes the accurate determination of the Ag/Sb occupancy of paramount importance. We report on the synthesis of polycrystalline AgSbTe2 by arc-melting, yielding nanostructured dense pellets. SEM images show a conspicuous layered nanostructuration, with a layer thickness of 25-30 nm. Neutron powder diffraction data show that AgSbTe2 crystalizes in the cubic Pm-3m space group, with a slight deficiency of Te, probably due to volatilization during the arc-melting process. The transport properties show some anomalies at ~600 K, which can be related to the onset temperature for atomic ordering. The average thermoelectric figure of merit remains around ~0.6 from ~550 up to ~680 K.

10.
Materials (Basel) ; 15(11)2022 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-35683119

RESUMO

Two perovskite materials with SrMo1-xAlxO3-δ (x = 0.1, 0.2) compositions have been synthesized by reduction from the corresponding scheelite phases, with SrMo1-xAlxO4-δ stoichiometry; the pertinent characterization shows that the defective perovskites can be used as anode materials in solid oxide fuel cells, providing maximum output power densities of 633 mW/cm2 for x = 0.2. To correlate structure and properties, a neutron powder diffraction investigation was carried out for both perovskite and scheelite phases. Both perovskites are cubic, defined in the Pm-3m space group, displaying a random distribution of Mo and Al cations over the 1a sites of the structure. The introduction of Al at Mo positions produced conspicuous amounts of oxygen vacancies in the perovskite, detected by neutrons. This is essential to induce ionic diffusion, providing a mixed ionic and electronic conduction (MIEC), since in MIEC electrodes, charge carriers are combined in one single phase and the ionic conductivity can be one order of magnitude higher than in a conventional material. The thermal expansion coefficients of the reduced and oxidized samples demonstrated that these materials perfectly match with the La0.8Sr0.2Ga0.83Mg0.17O3-δ electrolyte, La0.4Ce0.6O2-δ buffer layer and other components of the cell. Scanning electron microscopy after the test in a real solid oxide fuel cell showed a very dense electrolyte and porous electrodes, essential requirements for this type of fuel. SrMo1-xAlxO3-δ perovskites are, thus, a good replacement of conventional biphasic cermet anodes in solid oxide fuel cells.

11.
RSC Adv ; 12(6): 3696-3707, 2022 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-35425360

RESUMO

A novel oxynitride Li0.94FePO3.84N0.16 with olivine structure (space group Pnma, no. 62) has been synthesized by heating a parent LiFePO4 precursor obtained by citrate chemistry in flowing ammonia at 650 °C. The polycrystalline sample has been characterized by X-ray and neutron powder diffraction (NPD), elemental and thermal analysis, scanning electron microscopy (SEM) and electrochemical measurements. Based on the existing contrast between the scattering lengths of the N and O species, a Rietveld refinement of the structure from NPD data revealed that N preferentially occupies the O2 positions, as likely required to fulfil the bonding power of N ions. The refined crystallographic formula implies an oxidation state of 2.2+ for Fe cations. The differential thermal analysis, in still air, shows a strong exothermic peak at 520-540 °C due to the combustion of C contents, which are embedding the olivine particles, as observed by SEM. The electrochemical measurements suggest a better performance for the nitrided sample relative to the unnitrided LiFePO4 material, as far as capacity and cyclability are concerned. A bond-valence energy landscape study reveals a decrease in the percolation activation energy of about 6% upon nitridation, concomitant with the better electrochemical properties of the oxynitride compound. Additionally, ceramic samples prepared under NH3 flow could be obtained as pure and well-crystallized olivine phases at milder temperatures (650 °C) than those usually described in literature.

12.
Dalton Trans ; 51(6): 2278-2286, 2022 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-35040857

RESUMO

The crystal structure of LuNiO3 perovskite has been examined below RT and across TN = 125 K by neutron powder diffraction. In this temperature region (2-298 K), well below the metal-insulator transition this oxide exhibits at TMI = 599 K, this material is insulating and characterized by a partial charge disproportionation of the Ni valence. In the perovskite structure, defined in the monoclinic P21/n space group, there are two inequivalent Ni sites located in alternating octahedra of different sizes. The structural analysis with high-resolution techniques (λ = 1.594 Å) unveils a subtle increase of the charge disproportionation as temperature decreases, reaching δeff = 0.34 at 2 K. The magnetic structure has been investigated from low-T NPD patterns collected with a larger wavelength (λ = 2.52 Å). Magnetic peaks are observed below TN; they can be indexed with a propagation vector k = (½, 0, ½), as previously observed in other RNiO3 perovskites for the Ni sublattice. Among the three possible solutions for the magnetic structure, the first one is discarded since it would correspond to a full charge ordering (Ni2+ + Ni4+), with magnetic moments only on Ni2+ ions, not compatible with the structural findings assessing a partial charge disproportionation. The best agreement is found for a non-collinear model with two different moments in Ni1 and Ni2 sites, 1.4(1) µB, and m 0.7(1) µB at 2 K, the ordered magnetic moments lying on the a-c plane. This is similar to that found for YNiO3. In complement, the magnetic and thermal properties of LuNiO3 have been investigated. AC susceptibility curves exhibit a clear peak centered at TN = 125 K, corresponding to the establishment of the Ni antiferromagnetic structure. This is corroborated by DC susceptibility and specific heat measurements. Magnetization vs. field measurements confirm that the system is antiferromagnetic down to 2 K, without any further magnetic change. This linear behavior is also observed in the paramagnetic regime (T > TN).

14.
An. R. Acad. Nac. Farm. (Internet) ; 87(4): 447-458, octubre 2021. ilus
Artigo em Espanhol | IBECS | ID: ibc-210554

RESUMO

Un escape de gas, un tren aproximándose, la cercanía de un fuego, una comida en mal estado o, sin ponerse en lo peor, una simple caricia o el saborear un buen vino, es cuestión de cómo percibimos el mundo físico a través de las percepciones sensoriales y como construimos una imagen en nuestro cerebro y su estudio ha fascinado a la humanidad a lo largo de milenios. Esta búsqueda y los hitos generados han sido galardonados con varios Premios Nobel y ha culminado en el Premio Nobel de medicina de 2021 que ha sido concedido a los norteamericanos David Julius, un bioquímico, profesor de la Universidad de California y Ardem Patapoutian, un biólogo molecular de origen armenio y nacido en Líbano, también investigador de la Universidad de California en La Jolla, por sus hallazgos acerca de los receptores de temperatura y tacto. Los revolucionarios descubrimientos de los canales iónicos TRPV1, TRPM8 y PIEZO realizados por los premiados han permitido comprender las bases moleculares de la percepción del calor, el frío, el dolor, las fuerzas mecánicas y la posición de nuestro cuerpo en el espacio, y como esas sensaciones de naturaleza tan variada se transforman en impulsos nerviosos en el SNC lo que nos permite generar una representación interna del mundo que nos rodea y adaptarnos a él. (AU)


A gas leak, an approaching train, the proximity of a fire, a rotten meal or simply a caress or tasting a good wine, it is a question of how we perceive the physical world through sensory perceptions and how we build an image in our brain and its study has fascinated mankind for millennia. These questions and the milestones generated have been awarded several Nobel Prizes and has culminated in the 2021 Nobel Prize in Medicine that has been awarded to the North Americans David Julius, a biochemist, professor at the University of California and Ardem Patapoutian, a molecular biologist of Armenian origin and born in Lebanon, also a researcher at the University of California, La Jolla, for their findings about temperature and touch receptors. The groundbreaking discoveries of the TRPV1, TRPM8 and PIEZO ion channels made by the laureates have provided insight into the molecular basis of the perception of heat, cold, pain, mechanical forces, and the position of our body in space, and how these sensations of such a varied nature are transformed into nerve impulses in the CNS that allow us to generate an internal representation of the world around us and adapt to it. (AU)


Assuntos
Humanos , Sensação Térmica , Propriocepção , Nociceptividade , Medicina , Tato
15.
Inorg Chem ; 60(18): 13990-14001, 2021 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-34496217

RESUMO

This study presents the influence of polymorphism on the magnetic properties of Co5TeO8. This compound with a spinel-like structure [Co2]A[Co3Te]BO8 was synthesized into two polymorphs: one disordered within a cubic Fd3̅m structure, where Co2+ and Te6+ ions are randomly distributed on the octahedral B sites [the disordered polymorph can also be presented as an inverse spinel of the formula Co(Co1.5Te0.5)O4] and the other ordered with a cubic P4332 structure where Co2+ and Te6+ ions are ordered on the B sites. The macroscopic magnetic measurements showed that both polymorphs present a ferrimagnetic ordering, below ∼40 K, and a second transition is also observed at 27 K for the ordered polymorph. Neutron powder diffraction data between room temperature and 1.7 K showed as well the presence of short-range magnetic ordered clusters, which appears for both polymorphs below 200 K. At lower temperature, these short-range orders are transformed into long-range ferrimagnetic orders. Below TC = 40 K, the colinear ferrimagnetic structure of the disordered polymorph is described with the I41/am'd' space group. The ordered polymorph undergoes an incommensurate ferrimagnetic spiral spin ordering below TC1 = 45 K, followed by a second magnetic phase transition at TC2 = 27 K. This last transition is associated with the emergence of an additional ferrimagnetic component and an abrupt change in the magnitude of the magnetic propagation vector k = [0, 0, γ] from γ = 0.086 at T = 30 K to γ ≈ 0.14 in the range between 27 and 1.7 K. The magnetic symmetry of the ordered polymorph is described with the P43(00γ)0 magnetic superspace group. We evidenced that the ordering of Co2+/Te6+ on the B sites changes all of the Co-Co and Co-O distances and thus all JAB, JAA, and JBB exchange interactions, between the A and B sites, which are able to stabilize the incommensurate spin modulation in the ordered polymorph.

16.
ACS Appl Mater Interfaces ; 13(36): 42927-42934, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34463469

RESUMO

The limit of the energy density and increasing security issues on sodium-ion batteries (SIBs) impede their further development. Solid-state sodium metal batteries are potential candidates to replace the present SIBs. However, low ionic conductivity and poor interface contact hinder their progress. In this work, the impact of Al doping on the crystalline structure and ionic transport in Na3.4Zr2(Si0.8P0.2O4)3 was studied by neutron powder diffraction. The ionic conductivity of Na3.5Zr1.9Al0.1Si2.4P0.6O12 achieves 4.43 × 10-3 S cm-1 at 50 °C. The polarization voltage of the Na||Na symmetric battery is about 40 mV after cycling for more than 1600 h. Moreover, a solid-state sodium-sulfur battery with a monolithic structure was constructed to alleviate the interfacial resistance problems. Its specific discharge capacity can still keep 300 mA h g-1 after 480 cycles at 300 mA g-1. The work provides a promising strategy to design solid-state sodium-sulfur batteries with high performances.

17.
Environ Sci Pollut Res Int ; 28(38): 53412-53431, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34031824

RESUMO

Globally, interest in the environment and its conservation is growing and primordial. Emissions abatement is one of the main challenges faced by different governments. Firstly, the emissions should be estimated, and two types of responsibilities or focuses stand out, the producer's and the consumer's. Based on the Multiregional Input-Output Methodology, this study determines Ecuador's responsibility in terms of CO2 emissions. It defines the economic sectors that have the greatest representation in these emissions, as well as establishing an assessment at the level of the Trade Balance. To do so, the EORA database was used. There has been a strong growth of Ecuador's Footprint of 145.26% from 2000 to 2015, with the transport and secondary sectors having the highest representation and the trade with the BRICS nations standing out. This result strengthens the need to foster a change in the consumption patterns of the population and the public administrations. It is therefore recommended that the authorities allocate part of the public budget to measures oriented to sustainable consumption. Amongst other measures, it would be advisable to extend the RENOVA Plan to private vehicles, as well as to launch awareness campaigns on the degree of sustainability of imported products. These types of measures could stop the strong growth in emissions per capita, essential to reduce the country's carbon footprint.


Assuntos
Dióxido de Carbono , Pegada de Carbono , Carbono , Dióxido de Carbono/análise , Demografia , Equador
18.
Foods ; 10(4)2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33921048

RESUMO

Obesity is considered a risk factor for the development of colorectal cancer. In rodents, high-fat (HF) diets are able to increase the formation of azoxymethane (AOM)-induced polyps. Polyphenol-rich apple extracts have antioxidant and anti-inflammatory activities and may induce an amelioration of the manifestations of colorectal cancer. Twenty-seven male Crl:CD-1 mice received AOM during four weeks and were subsequently divided into three groups fed a HF diet (n = 9 each group): a non-supplemented group, a second group supplemented with apple extract at 1%, and a third group supplemented with the same apple extract at 1.5%. Energy metabolism and the respiratory quotient were not affected by the supplementation with the apple extract. Although body weight was not affected by the treatment, the mice supplemented with the apple extract showed less signs of cachexia than the non-treated mice. In the intestine, the mice supplemented with the apple extract showed lower sucrase, dipeptidyl-peptidase IV, and aminopeptidase N activities, and less intestinal lesions (aberrant crypt foci and polyps). Administration of a polyphenol-rich apple extract reduces the number of neoplastic lesions in mice with AOM-induced colorectal cancer and contributes to preserve adipose tissue mass.

19.
ACS Catal ; 11(24): 15026-15039, 2021 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-34976431

RESUMO

A family of iron-doped manganese-related hollandites, K x Mn1-y Fe y O2-δ (0 ≤ y ≤ 0.15), with high performance in CO oxidation have been prepared. Among them, the most active catalyst, K0.11Mn0.876Fe0.123O1.80(OH)0.09, is able to oxidize more than 50% of CO at room temperature. Detailed compositional and structural characterization studies, using a wide battery of thermogravimetric, spectroscopic, and diffractometric techniques, both at macroscopic and microscopic levels, have provided essential information about this never-reported behavior, which relates to the oxidation state of manganese. Neutron diffraction studies evidence that the above compound stabilizes hydroxyl groups at the midpoints of the tunnel edges as in isostructural ß-FeOOH. The presence of oxygen and hydroxyl species at the anion sublattice and Mn3+, confirmed by electron energy loss spectroscopy, appears to play a key role in the catalytic activity of this doped hollandite oxide. The analysis of these detailed structural features has allowed us to point out the key role of both OH groups and Mn3+ content in these materials, which are able to effectively transform CO without involving any critical, noble metal in the catalyst formulation.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA