El carbón como fuente de energía

Cuadernillo didáctico y de divulgación científica presentado en la Semana de la Ciencia y la Tecnología.Peer reviewe

Influence of charcoal fines on the thermoplastic properties of coking coals and the optical properties of the semicoke

The aim of this work is to investigate the influence of the addition of organic inerts such as charcoal with a well-controlled particle size on the development of fluidity in three coking coals of different rank, maceral composition, and rheological properties. Three size fractions of charcoal, < 20, 20–80, and 80–212 μm, that can be considered as artificially prepared inertinites were used. The different charcoal fractions were added in amounts of 2, 5, 10, and 15 wt.% to selected high-quality coking coals with a Gieseler maximum fluidity (Fmax) of 373 (LF), 541 (MF), and 1891 (HF) ddpm. Increasing the amount of charcoal in the blend led to a progressive inverse exponential reduction in fluidity. This reduction was accompanied by a shortening of the fluid interval due to an increase in the softening temperature. In the case of the finest charcoal fraction, the inhibition of fluidity was even more pronounced. The HF coal with a relatively high fluidity was very sensitive to minimum amounts of charcoal addition, losing nearly half of its fluidity when 5 wt.% charcoal was added. A similar reduction in Fmax was also observed for LF, while MF with only a slightly higher fluidity displayed a different trend. From the results it can be seen that the inherent characteristics of a coal are critical factors that affect the extent of the reduction in fluidity caused by the incorporation of charcoal. The differences can be partially attributed to the amount of inertinite present in the parent coal and to the macerals within the inertinite, especially fusinite, semifusinite, and inertodetrinite. In relation to petrographic changes in the matrix of the semicokes, there is a general trend for isotropic material to increase and the size of the anisotropic textures to decrease with the addition of charcoal. Inclusions within the semicoke matrix also change according to the amount and the size of the charcoal added to coal.The research leading to these results has received funding from the Research Programme of the Research Fund for Coal and Steel (Grant Agreement number RFC-PR- 09024). Co-financing from PCTI grant COF11-39 and funds from MICINN (PIB2010BZ-00418 project)Peer reviewe

Spectral fluorescence variation of pollen and spores from recent peat-forming plants

The fluorescence properties of spores and pollen grains examined under ultraviolet incident light are used to assess the maturity of sedimentary organic matter and may have other applications in relation to recent sediments, in areas such as paleoenvironmental research. In this study pollen grains and spores from 33 species common in peat ecosystems were mounted on a glass slide in accordance with standard palynologycal procedures for recent plants. The main objective of this work was to assess the variability of fluorescence spectra of pollens and spores within a single species or even within a single sample. A minimum of 10 spectra were recorded from each sample and were averaged to obtain a spectrum characteristic of each sample. Both the average scattering and the scattering in different spectral regions were calculated using the standard deviation (SD) and the coefficient of variation (CV). The effect of the preparation techniques was assessed on some samples of Ericaceae taxa. The results indicated similar spectra for alcohol-washed and distilled water-washed samples, whereas the application of an acetolysis solution caused an increase in intensity and a shift to longer wavelengths. The spectra corresponding to the Sphagnum spores had the lowest intensity of all the families studied and displayed their maxima at the lowest registered wavelengths. They often showed a peak in the red region of the spectra, causing a larger scatter in fluorescence in this region. This peak is probably the result of wax or cytoplasmic material attached to the exospore. A significant number of Ericaceae taxa had two fluorescing pollen populations: a blue one of high intensity and smaller size and a yellow-orange one of low intensity and larger size. This difference could be related to different degrees of maturity of the pollen grains. In the case of pollen grains of herbaceous, tree and bush plants the largest scatter was found in the tails of the spectra toward the blue and red regions. The decreasing trend of fluorescence intensity with the shift of the spectra toward red was not observed in the pollen and spores of fresh plants. A good correlation was found between the spectral maxima (λmax) and the red-green quotient (QR/G) regardless of the type of plant.Financial support from MICINN (CGL2009-13990-C02-01/02), MINECO (CGL2013-46458-C2-1-R) and a FPU fellowship from MEC for J. Urbanczyk are gratefully acknowledged.Peer reviewe

Comparison of coal chars prepared in different devices at similar temperature

The characteristics of chars prepared in both a drop tube furnace (DTF) and a flat flame burner (FFB) at 1300 ºC from seven coals of different rank and maceral composition are the subject of this study. Coal samples sized and sieved to 36-75 μm were fed. The flame temperature of the FFB was achieved with a mixture of methane, air and oxygen whereas two different gas compositions were used in the DTF to account for sub-stoichiometric (2.5% O2) and close to stoichiometric (10% O2) oxygen levels. Determination of micropore surface area was carried out by CO2 adsorption isotherms at 0°C and char reactivity to air was measured at 550 °C in a thermogravimetric analyser (TGA). Overall similar combustion trends were obtained in both devices with burnout decreasing as coal rank increases and CO2 surface areas decreasing up to the medium volatile bituminous coal rank and increasing again for the anthracites. The results reveal a reasonable agreement between burnouts of FFB chars and low oxygen DTF chars whereas higher burnouts were obtained for higher oxygen DTF chars. The CO2 surface areas of the chars reasonably scattered without any systematic trend. The intrinsic reactivities of both series of chars from the DTF were similar to the corresponding FFB chars. Increasing coal rank, intrinsic reactivity of chars from the different combustion conditions decreased.The Principality of Asturias (Principado de Asturias), Project PC04-03 and the Ministry for Education (Ministerio de Educación), Project PSE2-2005Peer reviewe

Development of water-soluble polyanionic carbosilane dendrimers as novel and highly potent topical anti-HIV-2 microbicides

This is the author’s version of a work that was accepted for publication in Nanoscale."The development of topical microbicide formulations for vaginal delivery to prevent HIV-2 sexual transmission is urgently needed. Second- and third-generation polyanionic carbosilane dendrimers with a silicon atom core and 16 sulfonate (G2-S16), napthylsulfonate (G2-NS16) and sulphate (G3-Sh16) end-groups have shown potent and broad-spectrum anti-HIV-1 activity. However, their antiviral activity against HIV-2 and mode of action have not been probed. Cytotoxicity, anti-HIV-2, anti-sperm and antimicrobial activities of dendrimers were determined. Analysis of combined effects of triple combinations with tenofovir and raltegravir was performed by using CalcuSyn software. We also assessed the mode of antiviral action on the inhibition of HIV-2 infection through a panel of different in vitro antiviral assays: attachment, internalization in PBMCs, inactivation and cell-based fusion. Vaginal irritation and histological analysis in female BALB/c mice were evaluated. Our results suggest that G2-S16, G2-NS16 and G3-Sh16 exert anti-HIV-2 activity at an early stage of viral replication inactivating the virus, inhibiting cell-to-cell HIV-2 transmission, and blocking the binding of gp120 to CD4, and the HIV-2 entry. Triple combinations with tenofovir and raltegravir increased the anti-HIV-2 activity, consistent with synergistic interactions (CIwt: 0.33–0.66). No vaginal irritation was detected in BALB/c mice after two consecutive applications for 2 days with 3% G2-S16. Our results have clearly shown that G2-S16, G2-NS16 and G3-Sh16 have high potency against HIV-2 infection. The modes of action confirm their multifactorial and non-specific ability, suggesting that these dendrimers deserve further studies as potential candidate microbicides to prevent vaginal/rectal HIV-1/HIV-2 transmission in humans.

Biomarkers and inorganic proxies in the paleoenvironmental reconstruction of mires: The importance of landscape in Las Conchas (Asturias, Northern Spain)

We determined the lipid distributions (n-alkanes, n-alkan-2-ones, n-alkanoic acids), total organic carbon (TOC), total nitrogen (TN), Ca/Mg and ash content in Las Conchas mire, a 3.2 m deep bryophyte-dominated mire in Northern Spain covering 8000 cal yr BP. Bog conditions developed in the bottom 20 cm of the profile, and good preservation of organic matter (OM) was inferred from n-alkanoic acid distribution, with the exception of the uppermost 20 cm (last ca. 200 yr). Microbial synthesis of long chain saturated fatty acids from primary OM likely produced a dominance of short chain n-alkanoic acids with a bimodal distribution, as well as the lack of correspondence between the n-alkane and n-alkanoic acid profiles in the upper 20 cm. This was accompanied by an increase in ash content, a decrease in TOC and variation in n-alkane ratios, thereby suggesting significant changes in the mire, namely drainage and transformation to a meadow, in the last ca. 200 yr. The distribution of n-alkan-2-ones indicated an increase in bacterial source from the bottom of the record to 94 cm, whereas their distribution in the upper part could be attributed mainly to plant input and/or the microbial oxidation of n-alkanes. The different n-alkane proxies showed variations, which we interpreted in terms of changes in vegetation (Sphagnum vs. non-Sphagnum dominated phases) during the last 8000 cal yr BP. C23 was the most abundant homolog throughout most of the record, thereby suggesting dominant humid conditions alternating with short drier phases. However, such humid conditions were not linked to paleoclimatic variation but rather to geomorphological characteristics: Las Conchas mire, at the base of the Cuera Range, receives continuous runoff—even during drier periods—which is not necessarily accompanied by additional mineral input to peat, producing the development of Sphagnum moss typical of waterlogged ecotopes and damp habitats. Thus, although geochemical proxies indicated an ombrotrophic regime in the mire, geomorphological characteristics may make a considerable contribution to environmental conditions

Preliminary bulk characterization of Picacho tar sands, Pesca municipality (Boyacá, Colombia)

The tar sands are mined in Colombia for paving the local roads. An example of this use is the tar sands of the Picacho Formation, located in the municipality of Pesca, Boyacá. The objective of this study is providing a preliminary bulk characterization to evaluate this resource as a possible source of unconventional hydrocarbons in this area. The study is limited to two fronts of exploitation named the La Emilia and Santa Teresa mines. The methods used comprise elemental analysis, physico-mechanical test, SARA and pyrolysis. The results determine that the unit is composed of siliceous sandstones. The percentages of sulfur are low in most of the samples, except one that reaches 5%, the API gravity between 22.4 and 9.2 indicates that they range between medium and extra heavy crude, the oil fractional composition reflects a higher proportion of resins and asphaltenes, the pyrolysis indicates a high volatile content that completely distill at temperatures below 500ºC.En Colombia las arenas asfálticas las explotan para la pavimentación de vías terciarias, un ejemplo de esto son las areniscas asfálticas de la Formación Picacho, ubicadas en el municipio de Pesca, Boyacá. Este estudio tiene como objetivo una caracterización de las arenas asfálticas con el fin de tener una información preliminar sobre su variación en composición global entre dos frentes de explotación (minas La Emilia y Santa Teresa) con vistas a su posible potencial como fuente de hidrocarburos no convencionales. Los métodos comprenden análisis elementales, físico mecánico, SARA y pirólisis. Los resultados determinan que la unidad está compuesta por areniscas silíceas. Los porcentajes de azufre son bajos en casi todas las muestras, excepto una que alcanza 5%, la gravedad API determina que los crudos presentan un valor de 22,4 y 9,2 indicando que son crudos medios y extra pesados, las fracciones de crudo reflejan una mayor proporción de resinas y asfáltenos, la pirólisis indica un elevado contenido en volátiles que destila a temperaturas por debajo de 500ºC

Development of the marine Holocene environment in a drowned paleovalley with final anthropic influence in the Cartagena Bay (Murcia, SE Spain)

Sedimentological, paleobiological, mineralogical, and geochemical analyses of a sediment core retrieved on the seafront of Cartagena Bay were performed after high-resolution sampling. A wide series of dates obtained through radiocarbon and amino acid racemization proved that the Holocene record on the analyzed core began at ca. 7300 yr cal BP. Reinterpretation of the marine seismic profiles indicated that the beginning of this transgression was channeled along erosive paleochannels excavated on a coastal plain of, at least, MIS5c age. The Holocene paleoenvironmental evolution consisted of a first period marked by marine conditions with strong inputs from a fan delta linked to the reorganized fluvial network that occurred after the sudden rise of the base level, which caused a growing sedimentary prism. Later, the full marine environment was reflected in the development of a Posidonia-Cymodocea meadow hosting a rich biodiversity of marine species (mollusks, foraminifera, ostracoda). Around 3800 yr cal BP, the area underwent a profound change and a silting process started to alter the conditions, turning the area into a paucispecific brackish marsh environment in which mud deposition was dominant. Since Carthaginian times, arrangement works locally affected the record, allowing the arrival of some marine species due to port work (dredging) undertaken to gain depth and showing anthropic influence.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This paper was made possible by Grant HAR2017-85726-C2-2-P (Cambios ambientales y ocupación humana en el sector central del sureste ibérico) funded by MCIN/AEI/ 10.13039/501100011033 and by Grant HAR2017-85726-C2-1-P (Carthago Nova desde su entorno litoral: Paleotopografía y evolución medioambiental del Sector central del Sureste Ibérico. Dinámica poblacional y pro- ductiva) funded by MCIN/AEI/ 10.13039/501100011033.Peer reviewe

Underwater Quaternary record of the Cartagena Bay (Murcia, Spain)

Se perforó un sondeo de 30 m en la Bahía de Cartagena. El doble objetivo del mismo fue obtener datos sobre el antiguo frente marítimo de la ciudad romana y establecer la cronoestratigrafía y evolución paleoambiental. El sondeo (E3) se muestreó con alta resolución. Los sedimentos de la parte inferior (30-11,3 m) con predominio de colores marrones que indican condiciones oxidantes, la fauna de aguas salobres (Cerastoderma glaucum/Cyprideis torosa) y la sedimentación dominada por fangos y arenas, permiten interpretar el medio sedimentario estudiado como una llanura fangosa costera ligada a un abanico aluvial. Las edades AAR obtenidas revelan que todo el MIS5 está incluido en el registro. La parte superior (11,3-3,0 m), correspondiente al MIS 1, consiste en fangos orgánicos negros con arena y grava. Aparece una amplia diversidad de moluscos marinos en estadios juveniles de desarrollo. Todo esto representa el “cul de sac” de una bahía protegida donde se acumulaban restos vegetales, periódicamente afectada por llegadas de detríticos aluviales. Existe una somerización a techo del depósitoA new borehole was drilled at the end of the Cartagena Bay. The twofold aim of this operation was to obtain insights into the ancient Roman city seafront, and to establish its cronostratigraphy and paleoenvironmental evolution. A continuous 30 m long core (E3) was drilled and sampled with high resolution. The sediments of the lower part (30-11.3 m) with predominant brown colour indicating oxydizing conditions, the brackish-water fauna (Cerastoderma glaucum/Cyprideis torosa) and mud/sand dominance, allow to interpret the sedimentary environment as formed in a coastal mud flat linked to an alluvial fan. Consistent AAR dating ages reveal that the whole MIS5 record is included. The upper part of the record (11.3-3.0 m), which belongs to MIS 1, is made of black muddy sand and gravel. It appears a high diversity of marine mollusk species mostly in juvenile stage of development. This represents a complex environment: a “cul-d-sac” at the protected end of the bay where plant debris accumulated, being intruded by alluvial inputs. A growing continental influence likely occurred at the to