Nanostructured Thermoelectric Chalcogenides

Thermoelectric materials are outstanding to transform temperature differences directly and reversibly into electrical voltage. Exploiting waste heat recovery as a source of power generation could help towards energy sustainability. Recently, the SnSe semiconductor was identified, in single-crystal form, as a mid-temperature thermoelectric material with record high figure of merit, high power factor and surprisingly low thermal conductivity. We describe the preparation of polycrystals of alloys of SnSe obtained by arc-melting; a rapid synthesis that results in strongly nanostructured samples with low thermal conductivity, advantageous for thermoelectricity, approaching the amorphous limit, around 0.3–0.5 W/mK. An initial screening of novel samples Sn1−xMxSe, by alloying with 3d and 4d transition metals such as M = Mn, Y, Ag, Mo, Cd or Au, provides for a means to optimize the power factor. M=Mo, Ag, with excellent values, are described in detail with characterization by x-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electronic and thermal transport measurements. Rietveld analysis of XRD data demonstrates near-perfect stoichiometries of the above-mentioned alloys. SEM analysis shows stacking of nanosized sheets, with large surfaces parallel to layered slabs. An apparatus was developed for the simultaneous measurement of the Seebeck coefficient and electric conductivity at elevated temperatures

Acció dels andrògens en el testicle: un paper per a la meiosi

La funció que duen a terme els andrògens en l'espermatogènesi és, encara en certa mesura, enigmàtica: mentre que llur implicació és absolutament vital en la iniciació i en el manteniment del procés espermatogènic normal, la seva funció específica encara no està definida de manera precisa. Els andrògens, com les altres hormones esteroïdals, actuen a través del seu corresponent receptor anomenat receptor d'andrògens (AR). Fins avui, no hi ha gaire evidència que recolzi l'existència de diverses isoformes de l'AR com en el cas del sistema estrògensreceptor d'estrògens. Per tant, la pregunta de com els andrògens duen a terme la seva acció en l'espermatogènesi s'ha d'abordar definint dos processos: en primer lloc, s'han d'identifi- car amb total certesa els tipus cell. ulars testiculars capaços de respondre directament a l'estimulació androgènica. De manera específica, la qüestió per resoldre és quins són els tipus cellulars que expressen l'AR en el testicle. En segon lloc, sabent també que el complex del lligand unit a l'AR actua com a factor de transcripció, caldrà determinar quins són els gens que estaran activats o reprimits en les cèll. ules que tenen AR en resposta a l'estimulació androgènica. Fins que aquestes dues preguntes no estiguin contestades amb tota certesa, el mecanisme pel qual els andrògens regulen l'espermatogènesi serà, en el millor dels casos, especulatiu. En aquesta revisió presentem evidència que els andrògens actuen únicament a les cèll. ules somàtiques del testicle, com són les cèll. ules de Sertoli, les de Leydig, les mioides peritubulars i les cèll. ules del múscul llis que envolten els vasos sanguinis. A més a més, també discutim la possibilitat que els andrògens siguin indispensables per a l'inici de la meiosi, encara que continua essent desconegut el mecanisme pel qual els andrògens actuen en aquest procés.The role that androgens play in spermatogenesis still remains enigmatic: whereas their involvement is absolutely vital to the initiation and maintenance of the normal spermatogenic process, their specific role is yet to be defined. Androgens, like other steroid hormones, act via their corresponding receptor termed the androgen receptor (AR). To date, there is little evidence to support the notion that there are multiple forms of AR as is the case for the estrogen-estrogen receptor system. Thus, the question of how androgens manifest their action on spermatogenesis becomes one of defining two processes: First, the cell types within the testis that are capable of responding directly to androgen stimulation must be identified with absolute certainty. Specifically, this question can be stated as what cell types in the testis express AR. Second, given that the ligand-bound AR serves as a transcription factor, the question then becomes what are the genes turned on or off in AR positive cells in response to androgen stimulation? Until these two questions are unequivocally answered, the mechanism of how androgens regulate spermatogenesis will remain speculative at best. In this review we present evidence that androgens act solely at the level of the somatic cells of the testis, including Sertoli cells, Leydig cells, peritubular myoid cells and smooth muscle cells surrounding blood vessels. In addition, we discuss the likely possibility that androgens are indispensable for the onset of meiosis, albeit how they accomplish this remains a mystery

Fungal and ciliate protozoa are the main rumen microbes associated with methane emissions in dairy cattle

14 Pág. Departamento de Mejora Genetica AnimalMitigating the effects of global warming has become the main challenge for humanity in recent decades. Livestock farming contributes to greenhouse gas emissions, with an important output of methane from enteric fermentation processes, mostly in ruminants. Because ruminal microbiota is directly involved in digestive fermentation processes and methane biosynthesis, understanding the ecological relationships between rumen microorganisms and their active metabolic pathways is essential for reducing emissions. This study analysed whole rumen metagenome using long reads and considering its compositional nature in order to disentangle the role of rumen microbes in methane emissions.This research was financed by RTA2015-00022-C03-02 (METALGEN) project from the National Plan of Research, Development and Innovation 2013–2020 and the Department of Economic Development and Competitiveness (Madrid, Spain). A.L.G. was funded by FPI-INIA grant with reference FPI-SGIT2016-06.Peer reviewe

A dimensional reduction approach to modulate the core ruminal microbiome associated with methane emissions via selective breeding

17 Pág.  Departamento de ​Mejora Genética Animal (INIA)The rumen is a complex microbial system of substantial importance in terms of greenhouse gas emissions and feed efficiency. This study proposes combining metagenomic and host genomic data for selective breeding of the cow hologenome toward reduced methane emissions. We analyzed nanopore long reads from the rumen metagenome of 437 Holstein cows from 14 commercial herds in 4 northern regions in Spain. After filtering, data were treated as compositional. The large complexity of the rumen microbiota was aggregated, through principal component analysis (PCA), into few principal components (PC) that were used as proxies of the core metagenome. The PCA allowed us to condense the huge and fuzzy taxonomical and functional information from the metagenome into a few PC. Bivariate animal models were applied using these PC and methane production as phenotypes. The variability condensed in these PC is controlled by the cow genome, with heritability estimates for the first PC of ~0.30 at all taxonomic levels, with a large probability (>83%) of the posterior distribution being >0.20 and with the 95% highest posterior density interval (95%HPD) not containing zero. Most genetic correlation estimates between PC1 and methane were large (≥0.70), with most of the posterior distribution (>82%) being >0.50 and with its 95%HPD not containing zero. Enteric methane production was positively associated with relative abundance of eukaryotes (protozoa and fungi) through the first component of the PCA at phylum, class, order, family, and genus. Nanopore long reads allowed the characterization of the core rumen metagenome using whole-metagenome sequencing, and the purposed aggregated variables could be used in animal breeding programs to reduce methane emissions in future generations.This research was financed by the METALGEN project (RTA2015-00022-C03) from the national plan for research, development, and innovation 2013–2020 and the Department of Economic Development and Competitiveness (Madrid, Spain).Peer reviewe

A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system

It is commonly accepted that exoplanets with orbital periods shorter than one day, also known as ultra-short-period (USP) planets, formed further out within their natal protoplanetary disks before migrating to their current-day orbits via dynamical interactions. One of the most accepted theories suggests a violent scenario involving high-eccentricity migration followed by tidal circularization. Here we present the discovery of a four-planet system orbiting the bright (V = 10.5) K6 dwarf star TOI-500. The innermost planet is a transiting, Earth-sized USP planet with an orbital period of ~13 hours, a mass of 1.42 ± 0.18 M⊕, a radius of 1.166−0.058+0.061R⊕ and a mean density of 4.89−0.88+1.03gcm−3. Via Doppler spectroscopy, we discovered that the system hosts 3 outer planets on nearly circular orbits with periods of 6.6, 26.2 and 61.3 days and minimum masses of 5.03 ± 0.41 M⊕, 33.12 ± 0.88 M⊕ and 15.05−1.11+1.12M⊕, respectively. The presence of both a USP planet and a low-mass object on a 6.6-day orbit indicates that the architecture of this system can be explained via a scenario in which the planets started on low-eccentricity orbits then moved inwards through a quasi-static secular migration. Our numerical simulations show that this migration channel can bring TOI-500 b to its current location in 2 Gyr, starting from an initial orbit of 0.02 au. TOI-500 is the first four-planet system known to host a USP Earth analogue whose current architecture can be explained via a non-violent migration scenario

The Multiplanet System TOI-421: A Warm Neptune and a Super Puffy Mini-Neptune Transiting a G9 V Star in a Visual Binary

We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations—comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echellé Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Échelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements—and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P_b = 5.19672 ± 0.00049 days, a mass of M_b = 7.17 ± 0.66 M⊕, and a radius of R_b = 2.68^(+0.19)_(-0.18) R⊕, whereas the outer warm Neptune, TOI-421 c, has a period of Pc = 16.06819 ± 0.00035 days, a mass of M_c = 16.42^(+1.06)_(-1.04) M⊕, a radius of R_c = 5.09^(+0.16)_(-0.15) R⊕ and a density of ρ_c = 0.685^(+0.080)_(-0.072) g cm⁻³. With its characteristics, the outer planet (ρ_c = 0.685^(+0.080)_(-0.072) g cm⁻³) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Lyα transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed

Company for the Ultra-high Density, Ultra-short Period Sub-Earth GJ 367 b: Discovery of Two Additional Low-mass Planets at 11.5 and 34 Days

GJ 367 is a bright (V ~10.2) M1 V star that has been recently found to host a transiting ultra-short period sub-Earth on a 7.7 hr orbit. With the aim of improving the planetary mass and radius and unveiling the inner architecture of the system, we performed an intensive radial velocity follow-up campaign with the HARPS spectrograph - collecting 371 high-precision measurements over a baseline of nearly 3 yr - and combined our Doppler measurements with new TESS observations from sectors 35 and 36. We found that GJ 367 b has a mass of Mb = 0.633 +/- 0.050 ME and a radius of Rb = 0.699 +/- 0.024 RE, corresponding to precisions of 8% and 3.4%, respectively. This implies a planetary bulk density of rhob = 10.2 +/- 1.3 g cm-3, i.e., 85% higher than Earth's density. We revealed the presence of two additional non-transiting low-mass companions with orbital periods of ~11.5 and 34 days and minimum masses of = 4.13 +/- 0.36 ME and = 6.03 +/- 0.49 ME, respectively, which lie close to the 3:1 mean motion commensurability. GJ 367 b joins the small class of high-density planets, namely the class of super-Mercuries, being the densest ultra-short period small planet known to date. Thanks to our precise mass and radius estimates, we explored the potential internal composition and structure of GJ 367 b, and found that it is expected to have an iron core with a mass fraction of 0.91+0.07-.23 How this iron core is formed and how such a high density is reached is still not clear, and we discuss the possible pathways of formation of such a small ultra-dense planet

Sarcoma classification by DNA methylation profiling

Sarcomas are malignant soft tissue and bone tumours affecting adults, adolescents and children. They represent a morphologically heterogeneous class of tumours and some entities lack defining histopathological features. Therefore, the diagnosis of sarcomas is burdened with a high inter-observer variability and misclassification rate. Here, we demonstrate classification of soft tissue and bone tumours using a machine learning classifier algorithm based on array-generated DNA methylation data. This sarcoma classifier is trained using a dataset of 1077 methylation profiles from comprehensively pre-characterized cases comprising 62 tumour methylation classes constituting a broad range of soft tissue and bone sarcoma subtypes across the entire age spectrum. The performance is validated in a cohort of 428 sarcomatous tumours, of which 322 cases were classified by the sarcoma classifier. Our results demonstrate the potential of the DNA methylation-based sarcoma classification for research and future diagnostic applications