Search results for "40"
showing 10 items of 17345 documents
Phosphorus-Chalcogen Ring Expansion and Metal Coordination
2017
The reactivity of 4-membered (RPCh)2 rings (Ch = S, Se) that contain phosphorus in the +3 oxidation state is reported. These compounds undergo ring expansion to (RPCh)3 with the addition of a Lewis base. The 6-membered rings were found to be more stable than the 4-membered precursors, and the mechanism of their formation was investigated experimentally and by density functional theory calculations. The computational work identified two plausible mechanisms involving a phosphinidene chalcogenide intermediate, either as a free species or stabilized by a suitable base. Both the 4- and 6-membered rings were found to react with coinage metals, giving the same products: (RPCh)3 rings bound to the…
Testing the Dispersion of Nanoparticles in a Nanocomposite with an Ultra-Low Fill Content Using a Novel Non-Destructive Evaluation Technique
2022
A non-destructive evaluation (NDE) technique capable of testing the dispersion of nanoparticles in a nanocomposite would be of great use to the industry to check the quality of the products made and to ensure compliance with their specifications. Very few NDE techniques found in the literature can evaluate the level of dispersion of the nanoparticles in the whole nanocomposite. Here, a recently developed NDE technique based on pulsed phase thermography (PPT) in transmission mode was used to assess the particle dispersion in ultra-low, less than 0.05 wt%, Ag enriched polymeric based nanocomposite manufactured with an innovative nano-coating fragmentation technique. The phasegrams obtained wi…
Decomposition Process of Carboxylate MOF HKUST-1 Unveiled at the Atomic Scale Level
2016
HKUST-1 is a metal-organic framework (MOF) which plays a significant role both in applicative and basic fields of research, thanks to its outstanding properties of adsorption and catalysis but also because it is a reference material for the study of many general properties of MOFs. Its metallic group comprises a pair of Cu2+ ions chelated by four carboxylate bridges, forming a structure known as paddle-wheel unit, which is the heart of the material. However, previous studies have well established that the paddle-wheel is incline to hydrolysis. In fact, the prolonged exposure of the material to moisture promotes the hydrolysis of Cu-O bonds in the paddle-wheels, so breaking the crystalline n…
Land Snail Communities in Limestone Gorges from the Southern Part of the Metaliferi Mountains (Apuseni Mountains, Romania)
2018
Abstract This study focuses on terrestrial gastropod communities in a karst area, where the presence of water and the limestone generates favourable environment for land snails. Three limestone gorges were analysed located in the southeast of the Metaliferi Mountains. Four different habitats in three limestone gorges were analysed – Glodului, Cibului and Mada. A total of 42 species of land snails were identified. The terrestrial gastropod communities in the area are dominated by calciphile species, such as Granaria frumentum, Truncatellina cylindrica and Alopia bielzii madensis. The differences between the analysed habitats are not pronounced enough to be reflected in the structure of the s…
Scanning Tunneling Spectroscope Use in Electrocatalysis Testing
2010
Published version of an article from the journal: Materials (1996-1944). Also available from publisher: http://dx.doi.org/10.3390/ma3063675 The relationship between the electrocatalytic properties of an electrode and its ability to transfer electrons between the electrode and a metallic tip in a scanning tunneling microscope (STM) is investigated. The alkaline oxygen evolution reaction (OER) was used as a test reaction with four different metallic glasses, Ni78Si8B14, Ni70Mo20Si5B5, Ni58Co20Si10B12, and Ni25Co50Si15B10, as electrodes. The electrocatalytic properties of the electrodes were determined. The electrode surfaces were then investigated with an STM. A clear relationship between the…
From 1D coordination polymers to Metal Organic Frameworks by the use of 2-pyridyl oximes.
2020
The synthesis and characterization of coordination polymers and metal&ndash
Synthesis and characterization of ferrocene-based Schiff base and ferrocenecarboxaldehyde oxime and their adsorptive removal of methyl blue from aque…
2018
Abstract The ferrocene-based Schiff base 3 was synthetized by reaction of ferrocenecarboxaldehyde 1 with 4-aminoantipyrine 2. However, the reaction of 1 with hydroxylamine affords ferrocenecarboxaldehyde oxime 4. Compounds 3 and 4 were fully characterized by IR, 1H, 13C and DEPT-135 NMR spectroscopy, elemental analyses and also by single crystal X-ray diffraction. Compounds 3 and 4 were used to remove anionic methyl blue dye from wastewater. The results established that both compounds have high adsorption capacity towards methyl blue. Langmuir adsorption capacity of compound 4 (464 mmol/g) is much higher than that of compound 3 (193 mmol/g) at 25 °C. The kinetics data was fitted well pseudo…
Methyl Radical in Clathrate Silica Voids. The Peculiar Physisorption Features of the Guest-Host Molecular Dynamics Interaction.
2016
EPR line shape simulations of CH3/SiO2 clathrates and comparison to CH3/N2O and CH3/SiO2 experiments reveal the motional conditions of the CH3 radical up to the unusual regime of its stability, the high-temperature diffusional regime, at 300 K. In the low-temperature region, the CH3 in clathrates is found to rotate around the in-plane axes even at as low temperatures as 3.8 K. However, nonrotating methyls performing only libration about the C2-axes as well as around the C3-axis are also found, proving the existence of special sites in the clathrate voids that begin to accumulate a significant fraction of methyl radicals at temperatures below approximately 7 K. A distinctive feature in the s…
Revisión bibliográfica y análisis sobre b-learning y la socialización del alumnado en educación primaria
2021
espanolLa modalidad educativa de b-learning se incorporo al sistema educativo hace algunos anos y se ha implantado con fuerza, sobre todo a nivel universitario. El objetivo del estudio es analizar las investigaciones publicadas sobre b-learning en la etapa de Educacion Primaria a traves de una revision bibliografica centrada en los ultimos 5 anos. Aunque el estudio confirma que la tendencia no ha cambiado y el modelo sigue teniendo mas presencia en niveles superiores, poco a poco, se van viendo estudios sobre b-learning en Educacion Primaria. En su mayoria, son estudios enfocados a la eficacia en cuanto al rendimiento academico, pero podemos encontrar investigaciones donde el foco de estudi…
Some critical remarks on the paper “A note on the metrizability of tvs-cone metric spaces” / Некоторые критические замечания о работе «Заметки о метр…
2018
This short and concise note provides a detailed exposition of the approach and results established by (Lin et al, 2015, pp.271-279). We show that the obtained results are not particularly surprising and new. Namely, using an old result due to K. Deimling it is indicated that tvs-cone metric spaces over solid cones are actually cone metric spaces over normal solid cones. Hence, there are only cone metric spaces over normal solid cones or over normal non-solid cones. One question still unanswered is whether an ordered topological vector space with a non-normal non-solid cone exists. / В представленных, в данной статье, заметках приведен подробный обзор методов и полученных результатов исследо…