Search results for "barium"
showing 10 items of 262 documents
Potamogeton pusillus agg. in Tajikistan (Middle Asia)
2011
The locality of <em>Potamogeton berchtoldii</em> Fieber, the new species to the flora of Tajikistan (Middle Asia), together with its ecological conditions are presented. Additionally, the list of herbarium specimens of <em>P. pusillus</em> L. s. stricto gathered in Tajikistan and few specimens of <em>P. berchtoldii</em> collected from the area of adjacent countries are also provided. Taxonomical position of the species within the <em>Potamogeton pusillus</em> aggregation, the main morphological features of both taxa and possibility of finding other localities are discussed.
Orthotrichum pilosissimum (Orthotrichaceae), a new moss from arid areas of Nevada with unique axillary hairs
2011
Abstract Orthotrichum pilosissimum is described from herbarium material and recently collected specimens in the state of Nevada. Its specific epithet refers to the diagnostic hyper-developed axillary hairs, which are frequently longer than 1 mm, multiseriate and branched, covering most of the stems surface and sometimes protruding from the foliose shoots. These hairs are not only unique in the genus but also among mosses, providing a reliable diagnostic character for the new taxon. Additional gametophytic and sporophytic characters that contribute to its taxonomic delimitation are also given.
Taxonomic notes and distribution of taxa of Orobanche gr. minor (Orobanchaceae) from Tunisia
2015
AbstractNew records for the flora of Tunisia and, in part, for North Africa of taxa of Orobanche sect. Orobanche subsect. Minores (Beck) Teryokhin, are reported. These records come from field research carried out between 2010 and 2014 in the Kroumiria region in northwestern Tunisia and herbarium studies. Infraspecific taxa and chorological data about the identified taxa (Orobanche amethystea Thuill., Orobanche canescens C. Presl, Orobanche hederae Duby, Orobanche litorea Guss., Orobanche minor Sm. and Orobanche pubescens d’Urv.) are reported. Literature data on host and distribution are also revised. Orobanche litorea is new to North Africa, and O. canescens has been confirmed for North Afr…
First-principles calculations of surfaceHcenters inBaF2
2010
H center, a hole trapped at an interstitial anion site, placed on the 111 surface of Barium fluoride BaF2 has been studied by using density functional theory DFT with hybrid exchange potentials, namely, DFT-B3PW. Two different configurations of surface H center are investigated carefully. Both surface H-center systems have strong relaxations because of the surface effect. In the configuration that the interstitial fluorine atom is within the surface, named case 1 in this paper, the unpaired electron is almost equally distributed onto the two atoms of the H center, which is quite different from the bulk H-center case. The other configuration with one of the F atoms of the H center located ab…
Inventory of the non‐native flora of Italy
2009
In this paper we present a comprehensive inventory of the non‐native vascular flora of Italy, which was produced within the project “A survey of the Italian non‐native flora”, funded by the Italian Ministry for the Environment. Previously published floristic accounts were the main source of information. Historical records were critically revised and integrated with recent literature, data from herbaria and some unpublished information, so as to obtain a complete, up‐to‐date catalogue of the non‐native vascular plant species that occur spontaneously in Italy. The inventory lists 1023 non‐native species and subspecies, which account for 13.4% of all the Italian flora. The Italian non‐native f…
Gada koka 2020 – Eiropas dižskābarža – herbārijs
2020
Latvijas Dendrologu biedrība (LDB) par 2020. gada koku izvēlējās Eiropas dižskābardi Fagus sylvatica L. Latvijas Universitātes Muzeja Botānikas un mikoloģijas kolekciju herbārijā glabājas arī šīs sugas pārstāvju herbārijs - žāvēti un presēti zariņi ar lapām. Rakstā ir Eiropas dižskābarža sugas apraksts un 5 attēli no LU Muzeja herbārija, ar informāciju par to ievākšanas vietām un laikiem.
Elemental fingerprint of wines from the protected designation of origin Valencia
2009
Abstract Inductively coupled plasma optical emission (ICP-OES), in combination with different chemometric approaches, has been used to verify the origin of different red wine samples from Utiel-Requena, Jumilla, Yecla and Valencia protected designation of origin (PDO). The ability of multivariate analysis methods, such as hierarchical cluster analysis (HCA), principal component analysis (PCA), classification and regression trees (CARTs) and discriminant analysis (DA), to achieve wine classification from their elemental contents has been investigated. The calculations were performed using 38 variables (contents of Al, Ba, Be, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Gd, Ho, K, La, Li, Lu, Mg,…
Local Environment of Yttrium in Y-Doped Barium Cerate Compounds
2006
The local structure of yttrium in Y-doped BaCeO3 compounds was studied using X-ray absorption spectroscopy (XAS) at the Y K-edge. Data analysis shows that the local environment of Y3+ changes, resulting in a distorted octahedron. The structural distortion found does not depend on the dopant amount at the investigated compositions, but on the level of hydration, as clearly demonstrated by the distortion increase in the BaCe0.9Y0.1O3-ä sample after the treatment in O2/H2O. In situ measurements performed in O2/H2O flux, which show that the distortion is retained at 753 K, are also reported. The observed significative structural changes seem to point out a preferential insertion of the hydroxyl…
Proton Dynamics in In:BaZrO3: Insights on the Atomic and Electronic Structure from X-ray Absorption Spectroscopy
2009
The local structure of Ba2+, Zr4+, and In3+ in In:BaZrO3 is investigated with EXAFS for samples having 0 to 75% In3+ content. It is found that indium can be inserted in any ratio in the host matrix oxide and that the oxygen coordination shell displays an In-O distance very similar to the Zr-O length. In the Zr-rich compositions, there is a preferred dopant-vacancy association that, however, does not give rise to dopant-proton interaction in the hydrated samples. The tendency of Ba2+ to be attracted toward the dopant site is attributed to the electrostatic interaction with the dopant and to the structural rearrangement around the In3+ site. Third cumulant analysis at high temperatures (up to…
Element variability in the coralline alga Lithophyllum yemenense as archive of past climate in the Gulf of Aden (NW Indian Ocean)
2017
This study presents the first algal thallus (skeleton) archive of Asian monsoon strength and Red Sea influence in the Gulf of Aden. Mg/Ca, Li/Ca, and Ba/Ca were measured in Lithophyllum yemenense from Balhaf (Gulf of Aden) using laser ablation inductively coupled plasma mass spectrometry, and Mg/Ca ratio oscillation was used to reconstruct the chronology (34 y). Oscillations of element rates corresponding to the algal growth between 1974 and 2008 were compared with recorded climate and oceanographic variability. During this period, sea surface temperatures (SST) in Balhaf recorded a warming trend of 0.55 degrees C, corresponding to an increase in Mg and Li content in the algal thallus of 2.…