128 research outputs found
Electronic structure of (μ2-CO)[(η5-C5H5)Rh(CO)]2 by UV photoelectron spectroscopy and CNDO calculations
No full textSynthesis, crystal structure, electrochemistry and molecular-orbital analysis of the piano-stool dimer [Mo2(?-C5H5)2(CO)4(NC5H4PPh2-2)2]
No full textThe addition of 2-(diphenylphosphino)pyridine (NC5H4PPh2-2) to an in situ prepared m-xylene solution of [Mo2(η-C5H5)2(CO)4](molar ratio 2 : 1), at room temperature, yields the complex [Mo2(η-C5H5)2(CO)4(NC5H4PPh2-2)2]1. Compound 1 is easily converted into the cationic molybdenum(II) mononuclear complex [Mo(η-C5H5)(CO)3(NC5H4PPh2-2)]PF62 by reaction with AgPF6. Reduction of 1 with Na or Na/Hg, in tetrahydrofuran, affords an air-sensitive solution containing Na[Mo(η-C5H5)(CO)2(NC5H4PPh2-2)]3, together with minor products. Electrochemical measurements show that 1 undergoes a reversible one-electron oxidation followed by relatively slow decomposition of the electrogenerated species. The molecular structure of the diethyl ether solvate of 1 was determined by X-ray diffraction methods: monoclinic, space group P21/c, with a= 13.218(4), b= 19.485(6), c= 11.019(4)Å, β= 110.10(2)° and Z= 2. The centrosymmetric complex 1 is a typical piano-stool dimer in which two units share the leg coinciding with the Mo–Mo vector. Similarly to other compounds of this type, the M–M separation is quite long [Mo–Mo 3.276(3)Å], ca. 0.5 Å longer than the sum of the metal radii. The evidence for the single metal–metal bond (predicted by counting rules) and its role in providing the system's stability is discussed in terms of qualitative molecular orbital theory. The extended-Hückel method used appears sufficiently reliable as the total electronic energy minimizes for an intermetal separation close to the experimental one. The loss of σ bonding, on elongating Mo–Mo, is counterbalanced by the diminished repulsion between metal lone pairs (filled xy orbitals), thus the intermetallic distance is an evident compromise between attractive and repulsive electronic forces. Steric factors may not be so important. The theoretical implications for the eventual homolytic cleavage of the dimer are also underlined. A rationale is provided for the effects that follow the removal of one electron from the system
Genomewide linkage scan of schizophrenia in a large multicenter pedigree sample using single nucleotide polymorphisms
No full textA genomewide linkage scan was carried out in eight clinical samples of informative schizophrenia families. After all quality control checks, the analysis of 707 European-ancestry families included 1615 affected and 1602 unaffected genotyped individuals, and the analysis of all 807 families included 1900 affected and 1839 unaffected individuals. Multipoint linkage analysis with correction for marker-marker linkage disequilibrium was carried out with 5861 single nucleotide polymorphisms (SNPs; Illumina version 4.0 linkage map). Suggestive evidence for linkage ( European families) was observed on chromosomes 8p21, 8q24.1, 9q34 and 12q24.1 in nonparametric and/or parametric analyses. In a logistic regression allele-sharing analysis of linkage allowing for intersite heterogeneity, genomewide significant evidence for linkage was observed on chromosome 10p12. Significant heterogeneity was also observed on chromosome 22q11.1. Evidence for linkage across family sets and analyses was most consistent on chromosome 8p21, with a one-LOD support interval that does not include the candidate gene NRG1, suggesting that one or more other susceptibility loci might exist in the region. In this era of genomewide association and deep resequencing studies, consensus linkage regions deserve continued attention, given that linkage signals can be produced by many types of genomic variation, including any combination of multiple common or rare SNPs or copy number variants in a region. Molecular Psychiatry (2009) 14, 786-795; doi:10.1038/mp.2009.11; published online 17 February 2009</p
Das ästhetische Element in der historischen Erkenntnis. Croce und Windelband
No full textThe author makes a comparison between Benedetto Croce’s academic
writing of 1893, La storia ridotta sotto il concetto generale dell’arte, and Wilhelm
Windelband’s Rektoratsrede of 1894, Geschichte und Naturwissenschaft. By means
of this comparison, which is focused on the concepts of intuition and interest, the author
can reconstruct the dense network of sources of the theory of the history outlined by the
young Croce and by Windelband: from Lazarus to Simmel, from Köstlin to Labriola
Sleep-associated adverse events during the methylphenidate treatment of attention-deficit/hyperactivity disorder: A meta-analysis
No full textObjective: Sleep disturbances are a feature of attention deficit/hyperactivity disorder (ADHD) and an adverse event (AE) of methylphenidate (MPH) treatment. We sought to clarify MPH-associated sleep problems and how studies are affected by confounding factors. Data Sources: Published studies in English collected via online databases and unpublished data from www.clinicaltrials.gov and FDA websites. Sources were searched from inception to August 2017. Study Selection: We included blinded placebo-controlled studies of youth with ADHD conducted in naturalistic settings. This led to 35 studies yielding 75 observations of sleep-related AEs. These studies comprised 3079 drug-exposed and 2606 placebo-treated patients. Data Extraction: Two PhD reviewers reviewed each study for inclusion. Four PhD/PharmD reviewers extracted data in duplicate. Discrepancies were resolved by discussion or, if needed, by the senior author. Results: We found increased pooled relative risks (RRs) for MPH-associated sleep-related AEs for insomnia, initial insomnia, middle insomnia, combined insomnia, and sleep disorder. Several sample or study design features were significantly associated with the RR for sleep-related AEs and the MPH formulation studied. After correcting for confounding, we found significant differences among drugs. We show that the RR, and its interpretation, is constrained by the placebo AE rate. Conclusions: Several types of insomnia and sleep problems are associated with MPH treatment. Study design and sample features influence the RR statistic. By showing that the rate of placebo AEs impacts the RR, we provide the field with a useful covariate for adjusting RR statistics
Radio Base Stations and User Terminals Based on a Novel E-Shaped Patch Antenna for WWLAN Applications
No full text
Site selectivity in carbon monoxide insertion into a PtC σ-bond of the binuclear complex [(CH3)ClPt(μ-Cl) (μ-Ph2PPy) Pt(CH3)(DMSO)]DMSO. Structural characterization of the derivatives [(CH3CO)ClPt(μ-Cl)(μ-Ph2 PPy)Pt(CH3)(DMSO)] and [(CH3)ClPt(μ-Ph2PPy)2Pt(COCH3)]+
No full textTitle full: Site selectivity in carbon monoxide insertion into a PtC σ-bond of the binuclear complex [(CH3)ClPt(μ-Cl) (μ-Ph2PPy) Pt(CH3)(DMSO)]DMSO. Structural characterization of the derivatives [(CH3CO)ClPt(μ-Cl)(μ-Ph2 PPy)Pt(CH3)(DMSO)] and [(CH3)ClPt(μ-Ph2PPy)2Pt(COCH 3)]+. Carbon monoxide reacts with [(CH3)ClPt(μ-Cl)(μ-Ph2PPy)Pt(CH3) (DMSO)]DMSO, 1, to give [(CH3CO)ClPt(μ-Cl)(μ-Ph2 PPy)Pt(CH3)(DMSO)] 2. The insertion of CO into a platinum-carbon σ-bond of 1 shows a site selectivity, occurring at the Pt CH3 bond involving the metal atom connected to the P atom of the 2-(diphenylphosphino)pyridine (Ph2PPy). Under a carbon monoxide atmosphere for about 30 h, 1 forms the ionic compound [(CH3)ClPt(μ-Ph2PPy)2Pt(COCH3 )][Pt(CO)(COCH3)Cl2], 3. Complex 2 changes slowly into 3. It was not possible to obtain crystals of 2 or 3 suitable for X-ray investigations. A crystal species was isolated containing both 2 and 3 in a 1 : 1 ratio. The crystals are triclinic, space group P1 (no. 2), with a = 10.326(4) Å, b = 16.648(4) Å, c = 22.203(4) Å, α = 90.95(2)°, β = 96.50(2)°, γ = 95.44(2)°. The refinements, based on 3255 significant reflections, gave a final R value of 0.0621. The molecular structure of the neutral species 2 is similar to that of the parent compound 1, with a CH3CO group in place of a methyl. The structure of the anion of 3 was incompletely characterized because of disorder. The [(CH3)ClPt(μ-Ph2PPy)2Pt(COCH3 )]+ cation has a direct PtPt bond of 2.728(3) Å bridged by the two Ph2PPy ligands in a head-to-tail fashion. One of the Pt atoms completes its coordination with an acetyl group and is four-coordinate, whereas the second containing both a chlorine atom and a methyl group, is five-coordinate. Semi-empirical MO calculations for the cation have been performed, and show the dative nature of the PtII → PtII bond
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