Investigation about the electrochemical reduction in 3YSZ, related phase transition and consequences

In this research the electrochemical reduction of 3YSZ was investigated in various atmospheres with different oxygen partial pressures under an electric field of 25 V/cm at an environmental temperature of 800 {\deg}C. At a certain oxygen partial pressure insufficient incorporation of oxygen in the sample led to electrochemical reduction of YSZ which shows two clearly distinguishable states. First, greying of the material without a significant change in properties was detected which then transitioned into a second stage where a fundamental phase transition in the material happened within seconds from tetragonal 3YSZ towards FCC rocksalt ZrO or ZrON, dependent on the atmosphere. This phase transition is accompanied by blackening of the material, sudden increase in electrical conductivity, current concentration, and an obvious change in Raman spectrum.Comment: 17 pages, 5 figure

Comment on the letter of the Society of Vertebrate Paleontology (SVP) dated April 21, 2020 regarding 'Fossils from conflict zones and reproducibility of fossil‑based scientific data': Myanmar amber

Recently, the Society of Vertebrate Paleontology (SVP) has sent around a letter, dated 21st April, 2020 to more than 300 palaeontological journals, signed by the President, Vice President and a former President of the society (Rayfield et al. 2020). The signatories of this letter request significant changes to the common practices in palaeontology. With our present, multi-authored comment, we aim to argue why these suggestions will not lead to improvement of both practice and ethics of palaeontological research but, conversely, hamper its further development. Although we disagree with most contents of the SVP letter, we appreciate this initiative to discuss scientific practices and the underlying ethics. Here, we consider different aspects of the suggestions by Rayfield et al. (2020) in which we see weaknesses and dangers. It is our intent to compile views from many different fields of palaeontology, as our discipline is (and should remain) pluralistic. This contribution deals with the aspects concerning Myanmar amber. Reference is made to Haug et al. (2020a) for another comment on aspects concerning amateur palaeontologists/citizen scientists/private collectors

Comment on the letter of the Society of Vertebrate Paleontology (SVP) dated April 21, 2020 regarding “Fossils from conflict zones and reproducibility of fossil‑based scientific data”: Myanmar amber

Non peer reviewe

Visible light emissions during flash sintering of 3YSZ are thermal radiation

Flash sintering enables the densification of ceramics at low furnace temperatures in a few seconds by the application of an electric field to the specimen. One of the earliest mechanisms proposed to explain the rapid densification involves the generation of Frenkel defects. Light emission during flash sintering is often interpreted as electroluminescence from electron-hole pair recombination, in support of this mechanism. In this work, experimental investigation of the emissions during flash sintering of the most widely studied ceramic, 3YSZ, shows that the visible spectrum can be explained completely in terms of black body (thermal) radiation resulting from the Joule heating of the specimen rather than electroluminescence. Apparent peaks in the spectrum are experimental artefacts associated with the equipment. There is no evidence in the visible emission spectrum during flash sintering of 3YSZ for electron-hole pair recombination associated with Frenkel pair formation or for any mechanism other than Joule heating

Zerstoerungsfreie Dichtheitspruefung von Grundstuecksentwaesserungsleitungen. 1. Entwicklung eines Pruefgeraetes zur zerstoerungsfreien Dichtheitspruefung von Grundstuecksentwaesserungsleitungen. 2. Erarbeitung zulaessiger Wasserverluste fuer die zerstoerungsfreie Dichtheitspruefung von Grundstuecksentwaesserungsleitungen

Available from TIB Hannover: RN 6966(74/2001) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Genetic diversity of the Atacama Desert shrub Huidobria chilensis in the context of geography and climate

Highlights: • Huidobria chilensis is an endemic shrub distributed in the south of the Atacama Desert with a disjunct population at the northern coast. • Population and genetic structure correlate with geographic distance and geological factors. • Rain fall and fog, as well as ground water, must be regarded as important factors for populations at the coast and the Andean valleys, respectively. • A combination of different software tool to analyze GBS data allowed a good understanding of the population structure and genetic diversity. Abstract: Survival in hyperarid deserts is a major challenge for life in general and for plants in particular. The Atacama Desert presents harsh conditions such as limited rainfall, crusted soils, high soil salinity, high altitude, and intense solar radiation. These conditions, together with paleoclimatic variations over the last 10 million years, have influenced the genetic structure and connectivity of plant populations, resulting in a diverse flora with high endemism. However, the diversification of most lineages appears to be relatively recent, in contrast to the reported age of the Atacama Desert and the onset and expansion of hyperarid conditions since the late Oligocene and early Miocene. A prominent exception is Huidobria chilensis (Loasaceae), which is thought to be endemic to the Atacama since the Eocene. However, it is still not understood why this plant has been successful in adapting to the harshening environmental conditions. To investigate its genetic structure in relation to the history of the Atacama Desert, we studied 186 individuals from 11 populations using genotyping-by-sequencing (GBS). A total of nearly 56 k genome-wide single nucleotide polymorphisms (SNPs) were analyzed for population structure and genetic diversity. We identified four genetic clusters corresponding to geographic regions: the coastal region south of Tocopilla, the Cordillera de la Costa around Chañaral, and the Copiapó catchment 1 and 2. Genetic diversity within and between these clusters was analyzed along with rainfall, altitude, and landscape data. Although the genetic data support `isolation by distance’ as a major factor for genetic divergence between populations, the study also reveals the influence of topography on the distribution of H. chilensis and highlights the role of hydrologically connected watersheds and rivers in plant migration and colonization. This shapes the species' evolutionary trajectory and genetic diversity. Understanding these patterns in H chilensis lets one draw general conclusions about adaptation and survival strategies of plants in extreme desert environments such as the Atacama

Crown Group Lejeuneaceae and Pleurocarpous Mosses in Early Eocene (Ypresian) Indian Amber.

Cambay amber originates from the warmest period of the Eocene, which is also well known for the appearance of early angiosperm-dominated megathermal forests. The humid climate of these forests may have triggered the evolution of epiphytic lineages of bryophytes; however, early Eocene fossils of bryophytes are rare. Here, we present evidence for lejeuneoid liverworts and pleurocarpous mosses in Cambay amber. The preserved morphology of the moss fossil is inconclusive for a detailed taxonomic treatment. The liverwort fossil is, however, distinctive; its zig-zagged stems, suberect complicate-bilobed leaves, large leaf lobules, and small, deeply bifid underleaves suggest a member of Lejeuneaceae subtribe Lejeuneinae (Harpalejeunea, Lejeunea, Microlejeunea). We tested alternative classification possibilities by conducting divergence time estimates based on DNA sequence variation of Lejeuneinae using the age of the fossil for corresponding age constraints. Consideration of the fossil as a stem group member of Microlejeunea or Lejeunea resulted in an Eocene to Late Cretaceous age of the Lejeuneinae crown group. This reconstruction is in good accordance with published divergence time estimates generated without the newly presented fossil evidence. Balancing available evidence, we describe the liverwort fossil as the extinct species Microlejeunea nyiahae, representing the oldest crown group fossil of Lejeuneaceae

Reconstruction of <i>Microlejeunea nyiahae</i> based on the holotype and accompanying gametophytes.

<p>(A-F) Portions of sterile shoots in ventral view. (G-H) Portion of stem with a leaf in ventral view showing the large leaf lobule (dotted cells) and the lobe. (I) Median leaf lobe cells in top view. (J, L) Portion of shoot in ventral view with deeply bifid underleaf. (K) Free margin of leaf lobule showing hyaline papilla cell (gray) next to apical lobule tooth.</p

Results from the different divergence time estimates of Lejeuneinae.

<p>Age estimates are given as mean plus 95% confidence interval.</p

Cambay amber specimen AMNH-Tad-441-A.

<p>(A) Overview showing liverwort and moss inclusions as well as two dipterans. The arrowhead points to the holotype of <i>Microlejeunea nyiahae</i>. (B) Pleurocarpous moss. (C) Close-up showing upper portions of leaves of the moss inclusion. The prosenchymatous cells are well visible. Scale bars 1 mm (A) and 100 μm (B,C).</p