Search results for "Crown"
showing 10 items of 324 documents
Zirconium dioxide implants as an alternative to titanium: A systematic review
2020
Background: This systematic review evaluates the available scientific literature to demonstrate the aesthetic and clinical benefits and to determine the survival and the success of zirconium dioxide implants concerning titanium implants. Material and Methods: The electronic databases were searched until January 2020. Outcome measures were pink aesthetic score (PAS), white aesthetic score (WAS), bleeding on probing (BOP) and probing depth (PD). The addressed PICO question was: In partially edentulous patients in the upper-anterior sector, do zirconium dioxide implants provide aesthetic benefits over conventional titanium implants? Results: In the 15 articles included after the screening were…
Using ultrasound transmission velocity to analyse the mechanical properties of teeth after in vitro, in situ, and in vivo irradiation.
2000
Ultrasound transmission velocity (UTV) in isotropic material as a measure for the modulus of elasticity was correlated to mechanical properties. Changes in micromechanical properties of radiated teeth and influence of the oral cavity were to be evaluated nondestructively. UTV was measured in extracted teeth after 36 Gy and 62 Gy of in situ (enorally, with no contact to the oral cavity) and in vitro irradiation. Relative to controls, teeth subjected to 62 Gy in vivo showed higher UTV values for dentine and enamel. Sound teeth irradiated with 60 Gy in situ also showed higher UTV values for enamel, whereas dentine values were not significantly different from those of control. The mechanical pr…
12-MC-4 metallacrowns as versatile tools for SMM research
2015
Abstract The outstanding chemical and structural features of 12-MC-4 metallacrowns allow for versatile applications in magneto-chemical research. Herein, we present three novel approaches. The heterometallic, or magnetic director approach, provides a targeted way to attain unusual high-spin ground states in 12-MC-4 complexes. Further, the first cobalt metallacrowns of salicylhydroxamic acid have been established. They comprise a diamagnetic scaffold which facilitates an engineering of the magnetism of the central guest ion and thus three novel SMMs based on single Co(II) ions have been established. Finally, click chemistry has been utilized to realize a linkage of an azide-functionalized mo…
Enforcement of a high-spin ground state for the first 3d heterometallic 12-metallacrown-4 complex.
2014
Cu(II)(DMF)2Cl2[12-MC(Fe(III)N(Shi))-4](DMF)4·2DMF was synthesized as the first heterometallic transition metal 12-MC-4 complex. The purposeful placement of specific metal ions in the different sites of the metallacrown attains the establishment of a high-spin ground state. Inducing the anticipated superior exchange interactions, the central Cu(II) guest ion averts the common mutual cancellation of the spins, as is observed in the corresponding homometallic compounds.
Synthesis, Structure, and Magnetic Properties of the Oxalate-Based Bimetallic Ferromagnetic Chain {[K(18-crown-6)][Mn(H2O)2Cr(ox)3]}∞ (18-crown-6 = C…
2005
The salt [K(18-crown-6)][Mn(H2O)2Cr(ox)3]·0.5(18-crown-6) (1) has been prepared and structurally and magnetically characterized. It crystallizes in the P21/c space group [a = 21.011(2) A, b = 11.265(2) A, c = 15.748(3) A, β = 105.952(6)°, V = 3584(1) A3, and Z = 4] and contains [Mn(H2O)2Cr(ox)3]∞ chains connected through hydrogen bonding to form 2D anionic networks. The magnetic exchange is ferromagnetic [J = +2.23(2) cm-1] in the chain and also in between chains, reaching bulk ferromagnetic ordering below 3.5 K.
3d/4f Sandwich Complex Based on Metallacrowns.
2021
A novel lanthanide double-decker complex with nickel metallacrowns (MCs) as coordinating ligands has been synthesized. In the 3d/4f metallacrown complex TbIII[12-MCNiIIN(shi)-4]2, the central lanthanide ion is sandwiched between two [12-MC-4] units, forming an almost ideal square-antiprismatic coordination sphere. The resulting zenithal angles at the central lanthanide ion are smaller than those for previously reported sandwich compounds. Magnetic measurements reveal an energy barrier of 346 K under zero field and up to 585 K under 3200 Oe, the highest reported for metallacrowns with D4d symmetry.
A “Cation-less” Oxalate-Based Ferromagnet Formed by Neutral Bimetallic Layers: {[Co(H2O)2]3[Cr(ox)3]2(18-crown-6)2}∞ (ox = Oxalate Dianion; 18-crown…
2007
Neutral layers of the bimetallic oxalate complex {[Co(H2O)2]3[Cr(ox)3]2}∞ are formed in the presence of a crown ether and stabilized by hydrogen bonding. The resulting soluble ferromagnet orders at Tc = 7.4 K.
SYNTHESIS OF SELENIUM-CONTAINING CROWN ETHERS AND RELATED COMPOUNDS
1991
Abstract The synthesis of the first examples of selenium-containing crown ethers from the benzene diselenolate anion and dichalcogenated ethers is reported. The reaction is highly dependent on the experimental conditions, particularly the concentration. 1H NMR and mass spectrometry were used to confirm the structures of the new compounds.
Oxalate-Based Soluble 2D Magnets: The Series [K(18-crown-6)]3[MII3(H2O)4{MIII(ox)3}3] (MIII = Cr, Fe; MII = Mn, Fe, Ni, Co, Cu; ox = C2O42−; 18-crown…
2008
The synthesis and magnetic properties of the oxalate-based molecular soluble magnets with general formula [K(18-crown-6)] 3[M (II) 3(H 2O) 4{M (III)(ox) 3} 3] (M (III) = Cr, Fe; M (II) = Mn, Fe, Ni, Co, Cu; ox = C 2O 4 (2-)) are here described. All the reported compounds are isostructural and built up by 2D bimetallic networks formed by alternating M (III) and M (II) ions connected through oxalate anions. Whereas the Cr (III)M (II) derivatives behave as ferromagnets with critical temperatures up to 8 K, the Fe (III)M (II) present ferri- or weak ferromagnetic ordering up to 26 K.
The Dark Trienium: Valencia, 1389-1391. Unrest coinciding with an assault on the Jewish district
2012
Estudio de base documental sobre el auge del antijudaísmo desde 1371 y el asalto a la judería de Valencia en julio de 1391, al poco tiempo de su ampliación. Sitúa el hecho en el contexto de las tensiones políticas en la Corona de Aragón y en la ciudad, donde se enfrentaban sendos bandos: actuaciones entre 1375 y 1392 del inquisidor Nicolau Eimeric (Directorium inquisitorum) contra herejes y su condena de obras de Ramon Llull. Cortes de 1388-1389. Guerras en el ámbito pirenaico en 1390. Políticas de abastecimiento y defensa de la ciudad de Valencia y oposición de villas y nobles del reino al municipio de la capital, que arma una milicia montada en mayo de 1391. Represión de maleantes y medid…