Search results for " complex"
showing 10 items of 3391 documents
Macrobiotus naginae sp. nov., a New Xerophilous Tardigrade Species from Rokua Sand Dunes (Finland)
2022
Animals that colonize soil show specific adaptations to soil. Compared to closely related species living on the surface, the limbs of soil-dwelling animals are often shortened, reduced, or absent to allow a less restricted passage through cavities between soil particles. This pattern of limb reduction has also been observed in tardigrades, where multiple lineages that colonized the below-ground habitat show independent reduction and/or loss of legs and claws. In the tardigrade superfamily Macrobiotoidea, leg and claw reductions are a common trait found in the Macrobiotus pseudohufelandi complex. This rarely found species complex currently contains four nominal taxa. Here we describe, with t…
Comment on “Crystallographic Snapshot of an Arrested Intermediate in the Biomimetic Activation of CO2”
2015
Out of focus: A recent Communication published in this journal describes the synthesis of [nBu4 N]HCO3 . The authors performed a single-crystal X-ray study that revealed a putative species described as an incipient hydroxide ion engaging in a long, and presumably weak, interaction with CO2 . Our recent exploration of the coordination chemistry of CO2 with small ions leads us to believe that such an exceptional bonding situation is unlikely. Instead, we argue that the crystal structure is that of [nBu4 N]O2 CCH3 and therefore not representative of the bulk powder from the synthesis.
Side‐on Coordination in Isostructural Nitrous Oxide and Carbon Dioxide Complexes of Nickel
2021
Abstract A nickel complex incorporating an N2O ligand with a rare η2‐N,N′‐coordination mode was isolated and characterized by X‐ray crystallography, as well as by IR and solid‐state NMR spectroscopy augmented by 15N‐labeling experiments. The isoelectronic nickel CO2 complex reported for comparison features a very similar solid‐state structure. Computational studies revealed that η2‐N2O binds to nickel slightly stronger than η2‐CO2 in this case, and comparably to or slightly stronger than η2‐CO2 to transition metals in general. Comparable transition‐state energies for the formation of isomeric η2‐N,N′‐ and η2‐N,O‐complexes, and a negligible activation barrier for the decomposition of the lat…
Придворные королевские церемонии и их рецепция в праздничной жизни Речи Посполитой
2020
The author traces the transition of the royal court of the Polish-Lithuanian Commonwealth to the Western European model of court ceremonies, which lasted for almost two centuries, from the sixteenth to the eighteenth centuries. Initially, they followed the ceremonial models of the House of Habsburg and, starting in the 1640s, the French ceremonial, refined at the Versailles of Louis XIV. Meant to extol the monarch in the eyes of subjects, such ceremonies became widespread under kings of the House of Vasa, Michał Korybut Wiśniowiecki, Jan III Sobieski, and the House of Wettin. Many etiquette elements and ceremonial patterns were borrowed and adapted to the needs of the wealthy Polish and Lit…
Experimental FTIR-MI and Theoretical Studies of Isocyanic Acid Aggregates
2023
Homoaggregates of isocyanic acid (HNCO) were studied using FTIR spectroscopy combined with a low-temperature matrix isolation technique and quantum chemical calculations. Computationally, the structures of the HNCO dimers and trimers were optimized at the MP2, B3LYPD3 and B2PLYPD3 levels of theory employing the 6-311++G(3df,3pd) basis set. Topological analysis of the electron density (AIM) was used to identify the type of non-covalent interactions in the studied aggregates. Five stable minima were located on the potential energy surface for (HNCO)2, and nine were located on the potential energy surface for (HNCO)3. The most stable dimer (D1) involves a weak, almost linear N-H⋯N hydrog…
Matrix Isolation FTIR and Theoretical Study of Weakly Bound Complexes of Isocyanic Acid with Nitrogen.
2021
Weak complexes of isocyanic acid (HNCO) with nitrogen were studied computationally employing MP2, B2PLYPD3 and B3LYPD3 methods and experimentally by FTIR matrix isolation technique. The results show that HNCO interacts specifically with N2. For the 1:1 stoichiometry, three stable minima were located on the potential energy surface. The most stable of them involves a weak, almost linear hydrogen bond from the NH group of the acid molecule to nitrogen molecule lone pair. Two other structures are bound by van der Waals interactions of N⋯N and C⋯N types. The 1:2 and 2:1 HNCO complexes with nitrogen were computationally tracked as well. Similar types of interactions as in the 1:1 complexes were …
La promozione della capacità di analisi di situazioni educative complesse nei futuri insegnanti di scuola primaria.The promotion of future primary sc…
2011
Il tema della capacità di risoluzione di problemi educativi da parte di coloro che si accingono a svolgere la professione di insegnante, implica l’acquisizione di strategie per reagire in modo adeguato alla complessità dei problemi che connotano le situazioni educative. Si presentano i risultati di una ricerca triennale che ha coinvolto in totale 450 studenti del corso di Laurea in Scienze della Formazione Primaria dell’Università di Palermo. Con la ricerca ci si è posti l’obiettivo di rilevare la capacità degli studenti di affrontare lo studio con un atteggiamento volto alla comprensione e alla soluzione dei problemi concreti con i quali ci si confronta nel lavoro educativo. Si è inteso pr…
La méthode de la complexité pour comprendre la plurisémiocité des discours numériques : de l’efficacité de TikTok
2023
Based on a corpus of videos collected on the Tik Tok platform, our study aims to analyse the plurisemicity and memetic functioning of these productions. We seek to show the effectiveness of these native productions of Tik Tok through a strategic and integrated use of different semis. This is why we are working on the analysis of digital discourses and post-dualist epistemological work in this field of language sciences. Through our analytical work, we wish to contribute to the questioning of written/oral, man/machine and text/image oppositions.
Firsts lysidinyl- and lysidinium-triphosphines Pd(II) complexes
2010
International audience; The preparation of first lysidinyl-triphosphine ligand (named Triphosline) is described in three steps which are first a Michael type addition of imidazolidine (or lysidine) to diethylvinylphosphonate, second a phosphonate reduction with LiAlH4 and third an anti-Markovnikov radical addition of the primary phosphine to diphenylvinylphosphine. The Triphosline behaves as a tridentate P-coordinating ligand in palladium(II) complexes. The dangling lysidine function is then cleanly and totally alkylated by methyl iodide to lead to a new kind of lysidinium-triphosphine complexes. Subsequent anion exchange with TlPF6 affords the first example of a chloride free lysidinium-tr…
Nuclear entry and egress of parvoviruses.
2022
Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A2 domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diameter of 18–26 nm, intact capsids can potentially pass into the nucleus through nuclear pore complexes (NPCs). This might be facilitated by active nuclear import, but capsids may also follow an alternative entry pathway that includes activation of mitotic factors and local transient disruption of the nuclear envelope. The nuclear entry is followed b…