1,721,095 research outputs found
Correction to: How to measure premature mortality? A proposal combining “relative” and “absolute” approaches (Population Health Metrics, (2021), 19, 1, (41), 10.1186/s12963-021-00267-y)
No full textFollowing publication of the original article [1], it was reported that the first name of each author was repeated as an initial. The correct authorship list is given in this Correction article and the original article [1] has been updated
Parameter orthogonalization for the Siler mortality model
No full textCorrelation and, in general, close relationships between parameters can cause problems in the estimation of a model and the consequent fluctuation in the trend of its coefficients. We show the connections existing between parameters in the Siler model, one of the most widely used in demography to approximate mortality over the entire life span, and propose a method to reduce them. Parameter orthogonalization via the Gram-Schmidt-Fisher scoring algorithm seems a promising technique for limiting identification issues and numerical instabilities often encountered when maximizing the likelihood
Synthesis, characterization and reactivity of platinum-substituted ketenes [PtX{eta(1)-C(PPh3))CO}L-2]BF4, (X = Me, Cl; L-2=1,5-cyclooctadiene, 1,2-bis(diphenylphosphino)ethane, cis-1.2-bis(diphenylphosphino)ethene). Steric and electronic effects of the ancillary ligands
No full textKetenylidenetriphenylphosphorane, Ph3PC=C=O, 1, has been used to synthesize platinum-substituted ketenes [PtMe{eta1-C(PPh3)CO}L2]BF4, 2a, b [L2=1,5-cyclooctadiene, cod (a), 1,2-bis(diphenylphosphino)ethane, diphos (b)]. Parent compound [PtCl{eta1-C(PPh3)CO}L2]BF4, 3, with L2=cis-1,2-bis(diphenylphosphino)ethene, diphoe, was also synthesized, which is stable only at low temperature. The stability of 2 and 3 and the reactivity of the C=C=O moiety have been examined and discussed in terms of the electronic and steric characteristics of the ancillary ligands, also taking into account the reactivity of the ‘PtXL2’ fragment with other carbonyl stabilized phosphorus ylides, Ph3PCHCOR (R=Me, Ph, OMe, OEt)
Synthesis and deprotonation reactions of five-membered cyclic (aminooxy)carbenes derived from Platinum(II) carbonyls
No full textThe synthesis and reactivity in deprotonation reactions of a series of five-membered cyclic (aminooxy)carbenes derived from Platinum(II) carbonyls are reported
Metal substituted ketenes: first 13C and 31P CP/MAS NMR determinations
No full textCross-polarization, combined with magic-angle spinning, has been employed to obtain high-resolution solid-state 13C and 31P NMR spectra of a series of solid, peculiar ketenes, also known as eta1-ketenyl derivatives, bearing as substituents a PPh3 moiety and a coordinatively unsaturated Pt(II) fragment. Solid–state NMR data found for trans-[PtCl2(eta2-C2H4){eta1-C(PPh3)CO}], trans-[PtCl2{eta1-C(PPh3)CO}2], Ph3PC=C=O, trans-[PtCl2(eta2-C2H4){eta1-CH(PPh3)COMe}], trans-[PtCl2{eta1-CH(PPh3)COMe}2] and Ph3PCHCOMe, are compared with NMR values obtained in solution. The general utility of the CP/MAS NMR technique in the study of unstable or insoluble complexes is discusse
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Catalytic transformations of diazo compounds promoted by platinum(0) and dicationic platinum(II) complexes
No full textTaormin
SYNTHESIS OF O-CO-ORDINATED PLATINUM(II) COMPLEXES OF CARBONYL-STABILIZED ARSONIUM YLIDES AND THE MECHANISM OF CONVERSION TO THEIR C-CO-ORDINATED ISOMERS
No full textThe reaction of [{PtCl(dppe)}2][BF4], [dppe=1,2-bis(diphenylphosphino)ethane] with ylides Ph3AsCHCOR (R = Me, Ph or OMe) led to novel platinum(II) complexes [PtCl(dppe){OC(R)CH(AsPh3)}]BF4 (R = Me 1, Ph 2 or OMe 3) in which the carbonyl stabilized arsonium ylides are co-ordinated to the metal centre via the oxygen carbonyl atom. These derivatives are not stable in chlorinated solvents and slowly undergo isomerization to their C-co-ordinated analogues 4-6 following a first-order rate law. The mechanism proposed for this rearrangement implies both intramolecular and free-ylide promoted intermolecular paths with k(obs) values of the whole process depending on the basicity of the ylide
PREPARATION AND CHARACTERIZATION OF PDII-YLIDE COMPLEXES OF TYPE (PD(CNR)(ETA-3-2-XC3H4)[PH3PC(H)COME])BF4 (X = H, ME - R = PARA-C6H4OME, C(ME)3, ME, C6H11, PARA-C6H4NO2) - CRYSTAL-STRUCTURE OF (PD[CNC(ME)3]-(ETA-3-2-MEC3H4)[PH3PC(H)COME])BF4
No full text- …
