Search results for "Lope"
showing 10 items of 2014 documents
Dimeric n-Alkyl Complexes of Rare-Earth Metals Supported by a Linked Amido−Cyclopentadienyl Ligand: Evidence for β-Agostic Bonding in Bridging n-Alk…
2002
The dimeric rare-earth hydrides [Ln(η^5:η^1-C_5Me_4SiMe_2NCMe_3)(THF)(μ-H)]_2 (Ln = Y, Yb) react with excess α-olefin H_2C ═ CHR (R = Et, ^nPr, ^nBu) in a 1,2-insertion to give the series of THF-free dimeric n-alkyl complexes [Ln(η^5:η^1-C_5Me_4SiMe_2NCMe_3)(μ-CH_2CH_2R)]_2 as isolable crystals. Single-crystal X-ray diffraction studies on the five derivatives [Y(η^5:η^1-C_5Me_4SiMe_2NCMe_2R‘)(μ-CH_2CH_2R)]_2 (R‘ = Me, R = Et, ^nBu; R‘ = Et, R = Et, ^nPr) and [Yb(η^5:η^1-C_5Me_4SiMe_2NCMe_3)(μ-CH_2CH_2^nBu)]_2 revealed that the centrosymmetric dimeric complexes consist of two trans-arranged [Ln(η^5:η^1-C_5Me_4SiMe_2NCMe_2R‘)] fragments connected by two μ-alkyl ligands. Most strikingly, there…
Group 3 and 4 metal alkyl and hydrido complexes containing a linked amido-cyclopentadienyl ligand: “constrained geometry” polymerization catalysts fo…
2002
Abstract In order to understand the nature of the putative cationic 12-electron species [M(η 5 :η 1 -C 5 R 4 SiMe 2 NR′)R″] + of titanium catalysts supported by a linked amido-cyclopentadienyl ligand, several derivatives with different cyclopentadienyl C 5 R 4 and amido substituents R′ were studied systematically. The use of tridentate variants (C 5 R 4 SiMe 2 NCH 2 CH 2 X) 2− (C 5 R 4 =C 5 Me 4 , C 5 H 4 , C 5 H 3 t Bu ; X=OMe, SMe, NMe 2 ) allowed the NMR spectroscopic observation of the titanium benzyl cations [Ti(η 5 :η 1 -C 5 Me 4 SiMe 2 NCH 2 CH 2 X)(CH 2 Ph)] + . Isoelectronic neutral rare earth metal complexes [Ln(η 5 :η 1 -C 5 R 4 SiMe 2 NR′)R″] can be expected to be active for pol…
A Dysprosium Metallocene Single-Molecule Magnet Functioning at the Axial Limit
2017
Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] (1Dy Cpttt=1,2,4‐tri(tert‐butyl)cyclopentadienide) by the triethylsilylium cation produces the first base‐free rare‐earth metallocenium cation [(Cpttt)2Dy]+ (2Dy) as a salt of the non‐coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low‐lying Kramers doub…
Efficient and accurate computation of Green's function for the Poisson equation in rectangular waveguides
2009
[1] In this paper, a new algorithm for the fast and precise computation of Green's function for the 2-D Poisson equation in rectangular waveguides is presented. For this purpose, Green's function is written in terms of Jacobian elliptic functions involving complex arguments. A new algorithm for the fast and accurate evaluation of such Green's function is detailed. The main benefit of this algorithm is successfully shown within the frame of the Boundary Integral Resonant Mode Expansion method, where a substantial reduction of the computational effort related to the evaluation of the cited Green's function is obtained.
Data from: Plant – herbivorous beetle networks: molecular characterization of trophic ecology within a threatened steppic environment
2015
DNA barcoding facilitates many evolutionary and ecological studies, including the examination of the dietary diversity of herbivores. In this study, we present a survey of ecological associations between herbivorous beetles and host plants from seriously threatened European steppic grasslands. We determined host plants for the majority (65%) of steppic leaf beetles (55 species) and weevils (59) known from central Europe using two barcodes (trnL and rbcL) and two sequencing strategies (Sanger for mono/oligophagous species and Illumina for polyphagous taxa). To better understand the ecological associations between steppic beetles and their host plants, we tested the hypothesis that leaf beetl…
Le «Facezie» di Poggio nel teatro spagnolo del “Siglo de oro”
2022
Un capitolo della fortuna europea del «Liber facetiarum» di Poggio Bracciolini riguarda le rielaborazioni e le riscritture di alcune di esse nelle commedie spagnole del secolo XVII (il cosiddetto “Siglo de oro”). In questo studio, dopo una preliminare ricognizione bibliografica sull’attuale status della ricerca sul «Liber facetiarum», vengono analizzati i modi di riscrittura di tre racconti del Bracciolini (fac. 157, 172, 203) in tre scene di commedie spagnole del XVII secolo, «La dama boba» ed «El perro del hortelano» di Lope de Vega e «Don Gil de las calzas verdes» di Tirso de Molina. A chapter of the European fortune of Poggio Bracciolini’s «Liber facetiarum» concerns the re-elaborations…
Is the Rigidity of SARS-CoV-2 Spike Receptor-Binding Motif the Hallmark for Its Enhanced Infectivity? Insights from All-Atom Simulations
2020
The severe acute respiratory syndrome coronavirus (SARS-CoV-2) pandemic is setting the global health crisis of our time, causing a devastating societal and economic burden. An idiosyncratic trait of coronaviruses is the presence of spike glycoproteins on the viral envelope, which mediate the virus binding to specific host receptor, enabling its entry into the human cells. In spite of the high sequence identity of SARS-CoV-2 with its closely related SARS-CoV emerged in 2002, the atomic-level determinants underlining the molecular recognition of SARS-CoV-2 to the angiotensin-converting enzyme 2 (ACE2) receptor and, thus, the rapid virus spread into human body, remain unresolved. Here, multi-m…
Effect of imidazo[1,2-α]pyrimidine derivatives on leukocyte function
2001
Objective and Design: A series of six imidazo[1,2-α]pyrimidine (IP) derivatives were evaluated for their effects on leukocyte functions in vitro as well as on the inflammatory response induced by zymosan in the mouse air pouch.¶Materials and Subjects: Human neutrophils and murine peritoneal macrophages were used for in vitro assays. Mouse air pouch was performed in Swiss mice.¶Treatment: Test compounds were incubated with either human neutrophils or mouse peritoneal macrophages at concentrations not showing cytotoxic effects. For in vivo experiments, IPs were injected into the air pouch.¶Methods: Elastase and myeloperoxidase release, superoxide generation and LTB4 production were assayed in…
Effects of caffeoyl conjugates of isoprenyl-hydroquinone glucoside and quinic acid on leukocyte function.
2002
The activity of three prenylhydroquinone glucosides (1-3) and four caffeoylquinic esters (4-7), obtained from Phagnalon rupestre, on elastase release, myeloperoxidase activity and superoxide and leukotriene B(4) production from polymorphonuclear leukocytes was determined. 4,5-Dicaffeoylquinic acid strongly inhibited elastase release with an IC(50) value of 4.8 microM. Methylated caffeoylquinic derivatives were the most potent inhibitors of myeloperoxidase (IC(50) near 60 microM), whereas both methylated and free carboxyl isomers inhibited superoxide production with similar potency (IC(50) between 27 and 42 microM). The monocaffeoyl conjugate of prenylhydroquinone glucoside (3), the most pot…
Bank-specific shocks and aggregate leverage: Empirical evidence from a panel of developed countries
2020
International audience; This paper investigates the link between shocks in the banking sector and aggregate leverage measured by the credit-to-GDP gap. Using a balanced panel of 15 countries for the period 1989–2016, we exploit the approach due to Gabaix (2011) and consider banking granular shocks as an indicator of banking distress. Using methods that account for potential endogeneity, we find that banking shocks Granger-cause aggregate leverage. In particular, banking shocks tend to increase the level of leverage and cause departures of the credit-to-GDP ratio from its long-term trend.