Unraveling Bulk and Grain Boundary Electrical Properties in La0.8Sr0.2Mn1-yO3 Thin Films

Grain boundaries in Sr-doped LaMnO3 thin films have been shown to strongly influence the electronic and oxygen mass transport properties, being able to profoundly modify the nature of the material. The unique behaviour of the grain boundaries can be correlated with substantial modifications of the cation concentration at the interfaces, which can be tuned by changing the overall cationic ratio in the films. In this work, we study the electronic properties of La0.8Sr0.2Mn1-yO3 thin films with variable Mn content. The influence of the cationic composition on the grain boundary and grain bulk electronic properties is elucidated by studying the manganese valence state evolution using spectroscopy techniques and by confronting the electronic properties of epitaxial and polycrystalline films. Substantial differences in the electronic conduction mechanism are found in the presence of grain boundaries and depending on the manganese content. Moreover, the unique defect chemistry of the nanomaterial is elucidated by measuring the electrical resistance of the thin films as a function of oxygen partial pressure, disclosing the importance of the cationic local non-stoichiometry on the thin films behavior

On the superconducting nature of the Bi-II phase of elemental Bismuth

The superconductivity in the Bi-II phase of elemental Bismuth (transition temperature $T_{\rm c}\simeq3.92$ K at pressure $p\simeq 2.80$ GPa) was studied experimentally by means of the muon-spin rotation as well as theoretically by using the Eliashberg theory in combination with Density Functional Theory calculations. Experiments reveal that Bi-II is a type-I superconductor with a zero temperature value of the thermodynamic critical field $B_{\rm c}(0)\simeq31.97$~mT. The Eliashberg theory approach provides a good agreement with the experimental $T_{\rm c}$ and the temperature evolution of $B_{\rm c}$. The estimated value for the retardation (coupling) parameter $k_{\rm B}T_{\rm c}/\omega_{\rm ln} \approx 0.07$ ($\omega_{\rm ln}$ is the logarithmically averaged phonon frequency) suggests that Bi-II is an intermediately-coupled superconductor.Comment: 6 pages, 2 figure

Habeant Corpus—they should have the body. Tools learners have the right to use

Grâce à des outils informatiques rapides, puissants, peu onéreux et aisément accessibles, l’utilisation des corpus a vu une véritable explosion au cours des vingt dernières années. Dans le domaine de l’apprentissage des langues étrangères, cependant, l’exploitation des corpus est essentiellement le fait des chercheurs, des auteurs de manuels et des enseignants, tandis que les bénéfices que les apprenants retirent de ces avancées sont la plupart du temps indirects. Rares, en effet, sont les enseignants qui permettent à leurs étudiants un accès direct aux corpus. Cet article défend l’idée que rien ne s’oppose à l’utilisation des corpus au moins par des apprenants « avancés » et que le fait d’encourager cette démarche active comporte des avantages considérables. Après avoir défini brièvement la logique de l’approche présentée, nous décrirons un cursus d’anglais dans lequel nous demandons aux apprenants d’appliquer les techniques d’analyse de corpus à un corpus existant ou confectionné par leurs soins. Nous décrirons ensuite les productions de nos propres étudiants en utilisant les mêmes techniques et outils, disponibles gratuitement sur Internet, et qui ne nécessitent qu’un degré minimal de maîtrise de l’informatique.With the advent of fast, powerful, cheap and accessible computer tools, the use of corpora has exploded in the last 20 years. In the field of language learning, however, their use is mainly restricted to researchers, course writers and teachers, while the benefits to the learner are largely second hand: rare is the teacher who allows a class direct access to corpus methodology. This paper argues that there is no reason not to trust at least advanced learners with corpus tools, and that there are significant advantages to encouraging a hands-on approach. After outlining the rationale underpinning this approach, we describe an English course where learners are required to apply corpus techniques to an existing corpus or one of their own devising. We then go on to describe our students’ own productions, using only corpus techniques and tools used by the learners themselves, all freely available on the internet and requiring minimal training

Laboratorium optimisasie van ‘n urea-formaldehied

The Indirect Tensile Strength (ITS) was used to characterise the soil stabilising properties of a urea-formaldehyde (UF) resin. The test soil was brown shale gravel. Synergistic strength improvements were obtained when combining the resin with anionic bitumen emulsion and dosing both at 2%. Performance levelled off above these concentrations. For full strength development, the soil moisture content must be reduced to below 3%. Optimum indirect tensile strength is obtained at formaldehyde to urea molar ratio of 2:1. Soil strength increases as the reaction pH is lowered but the need for adequate application times restricts it to pH > 4,5. The experimental results also suggest that the presence of appropriate organic matter is critical for effective soil stabilisation with UF resin.Die Indirekte Treksterkte (ITS) is gebruik om die grondstabilisasie-eienskappe van ‘n urea-formaldehied hars (UF) te kwantifiseer. Die toetsgrond was ‘n bruin skaliegruis. Kombinasie van die hars met ‘n anioniese bitumen emulsie toon sinergistiese sterkteverbetering wanneer beide doseer word op die 2% vlak. Werkverrigting plat af bokant hierdie konsentrasies. Vir volle sterkteontwikkeling moet die grondvogtigheid verlaag word tot onder 3%. Optimale indirekte treksterktes word behaal met ‘n formaldehied-tot-urea molverhouding van 2:1. Grondsterkte neem ook toe soos die reaksie pH verlaag word maar vir pH < 4,5 word die beskikbare aanwendingstyd ontoereikend. Die eksperimentele resultate dui ook daarop dat die teenwoordigheid van ‘n geskikte organiese fraksie in die grond krities is vir effektiewe stabilisasie met UF hars.The THRIP program of the Department of Trade and Industry and the National Research Foundation of South Africa as well as Megadev Pty. (Ltd.)http://www.saiche.co.za/article.aspam201

Retinoic acid drives intestine-specific adaptation of effector ILC2s originating from distant sites.

Adaptation of immune cells to tissue-specific microenvironments is a crucial process in homeostasis and inflammation. Here, we show that murine effector type 2 innate lymphoid cells (ILC2s) from various organs are equally effective in repopulating ILC2 niches in other anatomical locations where they adapt tissue-specific phenotypes of target organs. Single-cell transcriptomics of ILC2 populations revealed upregulation of retinoic acid (RA) signaling in ILC2s during adaptation to the small intestinal microenvironment, and RA signaling mediated reprogramming of kidney effector ILC2s toward the small intestinal phenotype in vitro and in vivo. Inhibition of intestinal ILC2 adaptation by blocking RA signaling impaired worm expulsion during Strongyloides ratti infection, indicating functional importance of ILC2 tissue imprinting. In conclusion, this study highlights that effector ILC2s retain the ability to adapt to changing tissue-specific microenvironments, enabling them to exert tissue-specific functions, such as promoting control of intestinal helminth infections

A redundant transcription factor network steers spatiotemporal Arabidopsis triterpene synthesis

25 Pág.Plant specialized metabolites modulate developmental and ecological functions and comprise many therapeutic and other high-value compounds. However, the mechanisms determining their cell-specific expression remain unknown. Here we describe the transcriptional regulatory network that underlies cell-specific biosynthesis of triterpenes in Arabidopsis thaliana root tips. Expression of thalianol and marneral biosynthesis pathway genes depends on the phytohormone jasmonate and is limited to outer tissues. We show that this is promoted by the activity of redundant bHLH-type transcription factors from two distinct clades and coactivated by homeodomain factors. Conversely, the DOF-type transcription factor DAG1 and other regulators prevent expression of the triterpene pathway genes in inner tissues. We thus show how precise expression of triterpene biosynthesis genes is determined by a robust network of transactivators, coactivators and counteracting repressors.This Article was written in loving memory of A. Van Moerkercke (1979–2021). The authors thank A. Bleys for critically reading the manuscript; D. Gasperini for kindly sharing the ProMYCs:NLS-VENUS reporter lines, and P. Vittorioso for the dag1 mutant, ProDAG1:GUS and DAG1 over-expressing lines; J. R. Wendrich and T. Eekhout for assistance in the launching and analysis of the scRNAseq experiment; and S. Desmet and G. Goeminne from the VIB Metabolomics Core – Ghent for the thalianol profiling. This work was supported by the European Community’s Seventh Framework Program (FP7/2007–2013) under grant agreement 613692-TriForC and H2020 Program under grant agreement 760331-Newcotiana to A.G.; the Special Research Fund from Ghent University to A.G. and A.R. (project BOF18/GOA/013), and M.M. (project BOF20/GOA/012); the Flemish Government (AI Research program) to Y.S.; the Research Foundation Flanders with research project grants to A.G. (G004515N and G008417N) and a postdoctoral fellowship to P.F.-C.; a Swiss National Science Foundation postdoctoral fellowship (P300PA_177831) to M.C.; and a China Scholarship Council PhD scholarship to Y.B. A.O. acknowledges funding support from the John Innes Foundation and the BBSRC Institute Strategic Program Grant ‘Molecules from Nature – Products and Pathways’ (BBS/E/J/000PR9790).Peer reviewe