This paper assesses the feasibility of producing syngas from sewage sludge via two pyrolysis processes: microwave-induced pyrolysis (MWP) and conventional pyrolysis (CP). The changes in the ...composition of the produced gas as a function of the pyrolysis treatment and the initial moisture content of the sludge were evaluated. It was found that MWP produced a gas with a higher concentration of syngas than CP, reaching values of up to 94vol%. Moreover, this gas showed a CO2 and CH4 concentration around 50% and 70%, respectively, lower than that obtained in the gas from CP. With respect to the effect of moisture on gas composition, this was more pronounced in CP than in MWP. Thus, the presence of moisture increases the concentration of H2 and CO2 and decreases that of CO, especially when CP was used. In order to elucidate the behaviour of CO2 during the pyrolysis, the CO2 gasification kinetics of the char obtained from the pyrolysis were investigated. It was established that in microwave heating the gasification reaction is much more favoured than in conventional heating. Therefore, the low concentration of CO2 and the high concentration of CO in the microwave pyrolysis gas could be due to the self-gasification of the residue by the CO2 produced during the devolatilization of the sewage sludge in the pyrolysis process.
We present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. This is the Third Catalog of Hard ...Fermi-LAT Sources (3FHL), containing 1556 objects characterized in the 10 GeV-2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog at the same energies (1FHL). The vast majority of detected sources (79%) are associated with extragalactic counterparts at other wavelengths, including 16 sources located at very high redshift (z > 2). Of the sources, 8% have Galactic counterparts and 13% are unassociated (or associated with a source of unknown nature). The high-latitude sky and the Galactic plane are observed with a flux sensitivity of 4.4 to 9.5 × 10−11 ph cm−2 s−1, respectively (this is approximately 0.5% and 1% of the Crab Nebula flux above 10 GeV). The catalog includes 214 new γ-ray sources. The substantial increase in the number of photons (more than 4 times relative to 1FHL and 10 times to 2FHL) also allows us to measure significant spectral curvature for 32 sources and find flux variability for 163 of them. Furthermore, we estimate that for the same flux limit of 10−12 erg cm−2 s−1, the energy range above 10 GeV has twice as many sources as the range above 50 GeV, highlighting the importance, for future Cherenkov telescopes, of lowering the energy threshold as much as possible.
Display omitted
•Pure MoO2 samples were grown by chemically driven close space vapour transport.•Sequential oxidative annealings were carried out to modify phase or conductivity.•Reductive annealings ...were carried out for samples converted to MoO3.•Crystal structure and electrical properties were monitored after each annealing.•MoO2 rich MoO2/MoO3 composite originates the conductivity in mixed samples.
The effect of reductive or oxidative annealings on pure MoO2 films was monitored by X-ray diffraction and four-probe electrical conductivity measurements. For partially oxidized samples, it was observed the expected conductivity decrease with respect to pristine MoO2, but reasonably high conductivity was measured as long as the samples showed a MoO2/MoO3 phase-mixture with relatively high MoO2 content. On the other hand, for completely oxidized (pure MoO3) samples, a very low conductivity, not measurable with the four-probe arrangement, was noticed. The results of these experiments, together with the observations of Raman chemical maps are discussed to shed some light on the origin of the electrical conductivity in MoOx. The occurrence of a MoO2/MoO3 composite was found to be crucial to obtain a conductive material. The results presented in this work are relevant for the use of MoOx as hole transport layer, transparent conductive oxide or other modern generation optoelectronic devices.
•Centenarians maintain intrinsic capacity longer than individuals who display ordinary aging.•Resilience is a determinant of health, and centenarians maintain it longer.•Centenarians have specific ...genetic features.
Centenarians are remarkable not only because of their prolonged life, but also because they compress morbidity until the very last moments of their lives, thus being proposed as a model of successful, extraordinary ageing. From the medical viewpoint, centenarians do not escape the physiological decline or the age-related diseases or syndromes (i.e. frailty), but the rate of such processes is slow enough to be counterbalanced by their increased intrinsic capacity to respond to minor stresses of daily life (i.e. resilience). These new concepts are reviewed in this paper. Allostatic stresses lead to a chronic low-grade inflammation that has led to the proposal of the “inflammaging” theory of ageing and frailty. The biology of centenarians, described in this review, provides us with clues for intervention to promote healthy ageing in the general population. One of the major reasons for this healthy ageing has to do with the genetic signature that is specific for centenarians and certainly different from octogenarians who do not enjoy the extraordinary qualities of centenarians.
BL Lacertae objects represent a large fraction (22%) of γ-ray sources in the Third Fermi Large Area Telescope catalog (3FGL). Nearly half of the BL Lac object population remains without a redshift ...because of their featureless optical spectra. We aim to increase the number of BL Lac objects with a redshift measurement by using the photometric technique. For this work, we have used six Swift-UVOT filters and SDSS g′, r′, i′, and z′ optical filters mounted on the 0.65 m SARA-CTIO located in Chile and the 1.0 m SARA-ORM in the Canary Islands. A sample of 45 sources was selected from the 3FGL catalog for which photometry was performed in 10 optical and UV filters to obtain redshift measurements. We found three sources with z > 1.3, while reliable upper limits have been provided for 17 sources. The results presented here bring the total number of high-z (z > 1.3) BL Lac objects to 29.
ABSTRACT
Blazars display variable emission across the entire electromagnetic spectrum, with time-scales that can range from a few minutes to several years. Our recent work has shown that a sample of ...five blazars exhibit hints of periodicity with a global significance ${\gtrsim}2\, \sigma$ at γ-ray energies, in the range of 0.1 GeV < E < 800 GeV. In this work, we study their multiwavelength emission, covering the X-ray, ultraviolet, optical, and radio bands. We show that three of these blazars present similar periodic patterns in the optical and radio bands. Additionally, fluxes in the different bands of the five blazars are correlated, suggesting a co-spatial origin. Moreover, we detect a long-term (≈10 yr) rising trend in the light curves of PG 1553+113, and we use it to infer possible constraints on the binary black hole hypothesis.
Jarosite and birnessite secondary minerals play a pivotal role in the mobility, transport and fate of trace elements in the environment, although geochemical interactions of these compounds with ...extremely toxic thallium (Tl) remain poorly known. In this study, we investigated the sorption behavior of Tl(I) onto synthetic jarosite and birnessite, two minerals commonly found in soils and sediments as well as in mining-impacted areas where harsh conditions are involved. To achieve this, sorption and desorption experiments were carried out under two different acidic conditions and various Tl(I) concentrations to mimic natural scenarios. In addition, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and inductively coupled plasma (ICP) analyses were conducted to determine the performance of both minerals for Tl(I) sequestration. Our results indicate that both phases can effectively remove aqueous Tl by different sorption mechanisms. Jarosite preferentially incorporates Tl(I) into the structure to form Tl(I)-jarosite and eventually the mineral dorallcharite (TlFe3(SO4)2(OH)6) as increasing amounts of Tl are employed. Birnessite, however, favorably uptakes Tl(I) through an irreversible surface adsorption mechanism, underlining the affinity of Tl for this mineral in the entire concentration range studied (0.5–5 mmol L−1). Lastly, the presence of Tl(I) in conditions where aqueous molar ratio Tl/Mn is ∼0.25 inhibits the formation of birnessite since oxidation of Tl(I) to Tl(III) followed by precipitation of avicennite (Tl2O3) take place. Thus, the present research may provide useful insights on the role of both jarosite and birnessite minerals in Tl environmental cycles.
Display omitted
•Jarosite and birnessite effectively remove aqueous Tl(I) by different sorption mechanisms.•Jarosite preferentially incorporates Tl(I) into the mineral structure to form Tl-jarosite.•Birnessite uptakes Tl(I) through an irreversible surface adsorption mechanism.•High loadings of aqueous Tl(I) inhibits the formation of birnessite, but not jarosite.•Oxidation of Tl(I) to Tl(III) followed by precipitation of avicennite take place at Tl/Mn 0.25.
This research provides advances on geochemical understanding of thallium (Tl) sorption behavior during jarosite and birnessite precipitation.
The aim of this work was to assess the uptake of citrate-coated magnetite nanoparticles (NPs) by wheat plants and its effect on the bioaccumulation and toxicity of individual and joint Cd2+ and Cr6+ ...levels. Seven-day assays were conducted using quartz sand as the plant growth substrate. The endpoints measured were seed germination, root and shoot lengths, and heavy metal accumulation. Magnetite exhibited very low toxicity, regardless of the wheat seedling NP uptake and distribution into roots and shoots. The seed germination and shoot length were not sensitive enough, while the root length was a more sensitive toxicity endpoint. The root length of wheat seedlings exposed to individual metals decreased by 50% at 2.67mgCd2+kg−1 and 5.53mgCr6+kg−1. However, when magnetite NPs (1000mgkg−1) were added, the root length of the plants increased by 25 and 50%. Cd2+ and Cr6+ showed similar and noninteractive joint action, but strongly impaired the wheat seedlings. In contrast, an interactive infra-additive or antagonistic effect was observed upon adding magnetite NPs. Thus, cadmium and chromium accumulation in vegetable tissues was considerately diminished and the toxicity alleviated.
Display omitted
•We assessed the effect of nanomagnetite on heavy metal toxicity in wheat plants.•Citrate-coated magnetite nanoparticles (NPs) exerted very low toxicity to plants.•Cadmium was more toxic than chromium and toxicity was mitigated by magnetite NPs.•Cadmium and chromium had a similar and noninteractive joint action on plants.•Metals showed an interactive infra-additive joint effect by adding magnetite NPs.
This article examines the description of places and buildings in a selection of classical, medieval, and Renaissance texts by analyzing their use of
descriptio/ekphrasis and the technique of ...amplificatio (distributio and enumeratio) in order to reveal their cultural biases. Several of the texts are well known, while others are not. The texts are: the Epistola 2.17 by Caius Plinius the Young (62-c. 117 AD); Petrarch’s letter describing his ascent of Mount Ventoux (1336), published in Familiares rerum libri 4.1; a Tratado de montería (written between 1453-1473) and an inspection visit report on the Montizón castle (1478; both concerning the Sierra de Segura of Jaen); and a poem called Terze Rime (1458) that describes a new palace built by Cosimo I de Medici in Renaissance Florence
Este artículo examina la descripción de lugares y edificios en una selección de obras clásicas, medievales y renacentistas con características genéricas diferentes con el deseo de revelar sus apoyos culturales. Varios son bien conocidos, otros no. Los textos son: la Epistola 2.17 de Cayo Plinio el Joven (62-c.117 AD); la carta sobre la subida al Monte Ventoso de Petrarca (1336) publicada en Familiares rerum libri 4.1; un Tratado de montería (escrito entre 1453- 1473) y una visita de inspección al castillo de Montizón (1478; ambos sobre la Sierra de Segura de Jaén); y un poema llamado Terze Rime (1458) que describe un nuevo palacio de Cósimo I de Medici en la Florencia renacentista.
PDF
