Search results for "Fig"
showing 10 items of 1359 documents
Visitor arrivals forecasts amid COVID-19: A perspective from the Africa team
2021
Abstract COVID-19 disrupted international tourism worldwide, subsequently presenting forecasters with a challenging conundrum. In this competition, we predict international arrivals for 20 destinations in two phases: (i) Ex post forecasts pre-COVID; (ii) Ex ante forecasts during and after the pandemic up to end 2021. Our results show that univariate combined with cross-sectional hierarchical forecasting techniques (THieF-ETS) outperform multivariate models pre-COVID. Scenarios were developed based on judgemental adjustment of the THieF-ETS baseline forecasts. Analysts provided a regional view on the most likely path to normal, based on country-specific regulations, macroeconomic conditions,…
Transition state theory thermal rate constants and RRKM-based branching ratios for the N((2)D) + CH(4) reaction based on multi-state and multi-refere…
2012
International audience; Multireference single and double configuration interaction (MRCI) calculations including Davidson (+Q) or Pople (+P) corrections have been conducted in this work for the reactants, products, and extrema of the doublet ground state potential energy surface involved in the N(2D) + CH4 reaction. Such highly correlated ab initio calculations are then compared with previous PMP4, CCSD(T), W1, and DFT/B3LYP studies. Large relative differences are observed in particular for the transition state in the entrance channel resolving the disagreement between previous ab initio calculations. We confirm the existence of a small but positive potential barrier (3.86 +/- 0.84 kJ mol-1…
Single cigar-shaped nanopores functionalized with amphoteric amino acid chains: experimental and theoretical characterization.
2012
We present an experimental and theoretical characterization of single cigar-shaped nanopores with pH-responsive carboxylic acid and lysine chains functionalized on the pore surface. The nanopore characterization includes (i) optical images of the nanostructure obtained by FESEM; (ii) different chemical procedures for the nanopore preparation (etching time and functionalizations; pH and electrolyte concentration of the external solution) allowing externally tunable nanopore responses monitored by the current-voltage (I-V) curves; and (iii) transport simulations obtained with a multilayer nanopore model. We show that a single, approximately symmetric nanopore can be operated as a reconfigurab…
Spin crossover complexes as building units of hydrogen-bonded nanoporous structures
2009
The paper reports on the synthesis, crystal structure, differential scanning calorimetry (DSC) and magnetic properties of a spin crossover salt of formula [Fe(bpp)2](cis,cis-1,3,5-Hchtc)·5.5 H2O (1) (bpp = 2,6-bis(pyrazol-3yl)pyridine; cis,cis-1,3,5-Hchtc = monoprotonated cyclohexanetricarboxylate dianion). The salt shows a porous structure with water molecules sitting in the channels. The electronic configuration of the Fe2+ ions is high-spin (HS). Desolvation of 1 yields a material exhibiting an abrupt spin crossover with a thermal hysteresis loop located near room temperature (T1/2↑ = 319 K and T1/2↓ = 309 K). Rehydration of this desolvated salt yields an essentially low-spin (LS) materi…
Thermoelectric properties of atomic-thin silicene and germanene nano-structures
2014
The thermoelectric properties in one- and two-dimensional silicon and germanium structures have been investigated using first-principles density functional techniques and linear response for the thermal and electrical transport. We have considered here the two-dimensional silicene and germanene, together with nanoribbons of different widths. For the nano ribbons, we have also investigated the possibility of nano structuring these systems by mixing silicon and germanium. We found that the figure of merit at room temperature of these systems is remarkably high, up to 2.5.
The Alloxysta (Hymenoptera: Figitidae: Charipinae) type material in the United States National Museum of Natural History and the Canadian National Co…
2013
AbstractAlloxysta Förster, 1869 (Hymenoptera: Figitidae) type material of 19 nominal species deposited in the Canadian National Collection of Insects (Ottawa, Ontario, Canada) and the United States National Museum of Natural History (Washington, District of Columbia, United States of America) were studied. Nine species are treated as valid: A. australiae (Ashmead, 1900), A. commensuratus Andrews, 1978, A. japonicus (Ashmead, 1904), A. lachni (Ashmead, 1885), A. longiventris Baker, 1896, A. minuscula Andrews, 1978, A. nothofagi Andrews, 1976, A. vandenboschi Andrews, 1978, and A. xanthopsis (Ashmead, 1896). The following synonymies are established: A. affinis (Baker, 1896) and A. quebeci And…
ChemInform Abstract: Total Synthesis of (+)-Phenguignardic Acid, a Phytotoxic Metabolite of Guignardia bidwellii
2014
(+)-Phenguignardic acid, a phytotoxic metabolite of the grape black rot fungus Guignardia bidwellii was synthesized, as well as its enantiomer, in eight steps from (R)-phenyllactic acid and 3-phenylprop-2-yn-1-ol. The formation of the carboxylate at a late stage, to avoid enolization of the precursor used in the central acetalization step, proved to be crucial. The synthesis of the natural product allowed the unabiguous assignment of its hitherto unknown absolute configuration.
Total Synthesis of (+)-Phenguignardic Acid, a Phytotoxic Metabolite ofGuignardia bidwellii
2013
(+)-Phenguignardic acid, a phytotoxic metabolite of the grape black rot fungus Guignardia bidwellii was synthesized, as well as its enantiomer, in eight steps from (R)-phenyllactic acid and 3-phenylprop-2-yn-1-ol. The formation of the carboxylate at a late stage, to avoid enolization of the precursor used in the central acetalization step, proved to be crucial. The synthesis of the natural product allowed the unabiguous assignment of its hitherto unknown absolute configuration.
Evidence for a different electronic configuration as a primary effect during compression of orthorhombic perovskites: The case of NdM3+ O3 (M=Cr, Ga)
2018
(Mg,Fe)SiO3 perovskite is the most abundant mineral of the Earth's lower mantle, and compounds with the perovskite structure are perhaps the most widely employed ceramics. Hence, they attract both geophysicists and material scientists. Several investigations attempted to predict their structural evolution at high pressure, and recent advancements highlighted that perovskites having ions with the same formal valence at both polyhedral sites (i.e., 3+:3+) define different compressional patterns when transition metal ions (TMI) are involved. In this study, in situ high-pressure synchrotron XRD measurements coupled with ab initio simulations of the electronic population of NdCrO3 perovskite are…
«Per non dar moto alle fabriche»: l'ingegnere regio Scipione Basta e la costruzione della cappella Roano nel duomo di Monreale
2015
«PER NON DAR MOTO ALLE FABBRICHE»: THE ROYAL ENGINEER SCIPIONE BASTA AND THE CONSTRUCTION OF THE ROANO CHAPEL IN THE CATHEDRAL OF MONREALE. In December 1686 the Royal Engineer Scipione Basta, a personality still largely to be investigated but which seems to portend a specific expertise in techno-constructive issues and in particular in structural reinforcement, was appointed by the Viceroyal Government to draw up a technical report concerning some delicate constructive aspects of the project of the architect fra Giovanni da Monreale for the chapel commissioned by the archbishop Roano for the cathedral. Due to the particular configuration of the building to be constructed –a domed octagonal …