Search results for "Metal"
showing 10 items of 7908 documents
Tiokruunueetterien metallikompleksit
2012
Tämä LuK-tutkielma käsittelee tiokruunueetterien metallikomplekseja. Tarkemman tarkastelun kohteeksi on valittu pelkkiä rikkidonoreita sisältävien tiokruunueettereiden hopea-, kulta-, kupari-, palladium- ja platinakompleksit, jotka ovat lisäksi homoleptisiä eli eivät sisällä tiokruunueetterien lisäksi muita ligandeja. Tutkielmassa on keskitetty lähinnä kompleksien rakenteisiin ja koordinaatiokemiaan.
Unlocking mixed oxides with unprecedented stoichiometries from heterometallic metalorganic frameworks for the catalytic hydrogenation of CO 2
2021
[EN] Their complex surface chemistry and high oxygen lattice mobilities place mixed-metal oxides among the most important families of materials. Modulation of stoichiometry in mixed-metal oxides has been shown to be a very powerful tool for tuning optical and catalytic properties. However, accessing different stoichiometries is not always synthetically possible. Here, we show that the thermal decomposition of the recently reported metal-organic framework MUV-101(Fe, Ti) results in the formation of carbon-supported titanomaghemite nanoparticles with an unprecedented Fe/Ti ratio close to 2, not achievable by soft-chemistry routes. The resulting titanomaghemite phase displays outstanding catal…
Alkyl-Substituted Aminobis(phosphonates) : Efficient Precipitating Agents for Rare Earth Elements, Thorium, and Uranium in Aqueous Solutions
2021
The efficient and environmentally sustainable separation process for rare earth elements (REE), especially for adjacent lanthanoids, remains a challenge due to the chemical similarity of REEs. Tetravalent actinoids, thorium, and traces of uranium are also present in concentrates of REEs, making their separation relevant. This study reports six simple water-soluble aminobis(phosphonate) ligands, RN[CH2P(O)(OH)2]2 (1 R = CH2CH3, 2 R = (CH2)2CH3, 3 R = (CH2)3CH3, 4 R = (CH2)4CH3, 5 R = (CH2)5CH3, 6 R = CH2CH(C2H5)(CH2)3CH3) as precipitating agents for REEs, Th, and U, as well as gives insight into the coordination modes of the utilized ligands with REEs at the molecular level. Aminobis(phospho…
“Olen tietoisempi, miten suomen kieli toimii” : havaintoja edistyneen suomenoppijan kielitaidosta täsmäopetushankkeen aikana
2018
Esittelemme tässä artikkelissa Turun yliopiston Täsmäopetusta edistyneille suomenoppijoille ‑hanketta ja tarkastelemme sellaisia edistyneen suomenoppijan kielitaitoon liittyviä ilmiöitä, jotka nousivat esiin tarjoamamme täsmä- eli yksilöopetuksen aikana. nonPeerReviewed
Momentum-space structure of surface states in a topological semimetal with a nexus point of Dirac lines
2016
Three-dimensional topological semimetals come in different variants, either containing Weyl points or Dirac lines. Here we describe a more complicated momentum-space topological defect where several separate Dirac lines connect with each other, forming a momentum-space equivalent of the real-space nexus considered before for helium-3. Close to the nexus the Dirac lines exhibit a transition from type I to type II lines. We consider a general model of stacked honeycomb lattices with the symmetry of Bernal (AB) stacked graphite and show that the structural mirror symmetries in such systems protect the presence of the Dirac lines, and also naturally lead to the formation of the nexus. By the bu…
Sand clams of Ganzirri marine coastal lagoon in Messina (Italy). Extraction and ICP-MS analysis
2008
This paper studies the possible forms or phases of heavy metals in sediments of a marine coastal lagoon, called Ganzirri, located in the Sicilian coast of the Messina’s strait by using sequential extraction. To reduce the extraction time of the Tessier method, the last step of speciation was carried out by mineralization in a microwave oven. Here we report the results of the distribution of As, Be, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, Se, Tl, V and Zn, in four fractions of sediments samples and the concentration of the same metals in clams. This study looked at three bivalve mollusc species, Tapes decussates, Chamelea gallina and Cardium edule, raised in the sediment considered and discussed the…
Phase equilibria of Pantelleria trachytes (Italy): constraints on pre-eruptive conditions and on the metaluminous to peralkaline transition in silici…
2018
Pantelleria Island is the type locality of pantellerite, an iron and alkali-rich rhyolite (P.I=molar Na2O+K2O/Al2O3 >1.05). Peralkaline rhyolites (i.e pantellerite and comendite) and trachytes usually represent the felsic end-members in continental rift systems (e.g., Pantelleria, Tibesti, Ethiopia, Afar, Kenya, Bain and Range, South Greenland) and in oceanic sland settings (Socorro Is., Easter Is., Iceland and Azores). The origin of peralkaline rhyolites in the different tectonic settings is still a matter of debate and three hypotheses have been suggested: (a) crystal fractionation of alkali-basalt in a shallow reservoir to produce a trachyte which subsequently gives rise to a pantelle…
New methodologies in transition metal catalysis. Organofluorine chemistry as the benchmark application.
2017
A lo largo de las últimas décadas, los compuestos organofluorados han encontrado numerosas aplicaciones dentro del campo de las industrias farmacéutica y agroquímica, así como en ciencias de los materiales. Dadas las singulares propiedades del átomo de flúor, éste es capaz de inducir alteraciones significativas en propiedades físico-químicas de las moléculas como lipofilia, distribución de cargas, acidez-basicidad, capacidad de formar enlaces de hidrógeno e incluso, equilibrios conformacionales. Sin embargo, la presencia de flúor en productos naturales es escasa. De hecho, la gran mayoría de las moléculas orgánicas que contienen flúor son sintéticas. De ahí el gran interés por parte de la c…