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31.
Christian Gérard Fumio Hiroshima Annalisa Panati Akito Suzuki 《Communications in Mathematical Physics》2011,308(2):543-566
We consider the Nelson model on some static space-times and investigate the problem of existence of a ground state. Nelson
models with variable coefficients arise when one replaces in the usual Nelson model the flat Minkowski metric by a static
metric, allowing also the boson mass to depend on position. We investigate the existence of a ground state of the Hamiltonian
in the presence of the infrared problem, i.e. assuming that the boson mass m(x) tends to 0 at spatial infinity. We show that if m(x) ≥ C |x|−1 at infinity for some C > 0 then the Nelson Hamiltonian has a ground state. 相似文献
32.
Romualdo Caputo Annalisa Guaragna Giovanni Palumbo Silvana Pedatella Francesco Solla 《Journal of carbohydrate chemistry》2013,32(4-5):631-634
In a recent paper2 we have reported the design and synthesis of 3-C-lithiated 5,6-dihydro-1,4-dithiin-2-yl[(4-methoxybenzyl)oxy]methane (1) which can be utilized as an allylic alcohol anion equivalent and leads to three-carbon elongations of various electrophiles by introduction of a fully protected hydroxypropenyl moiety. The latter contains a double bond, which can be unravelled to the cis configuration by diastereoselective removal3 of the dimethylene-disulfur bridge, as well as a protected primary hydroxyl group that, depending on the deprotection conditions used (DDQ/NaBH4 or DDQ), may either lead to the free allylic alcohol or to an α,β-unsaturated aldehyde. 相似文献
33.
34.
Martina Mazzoni Lorenzo Franco Alberta Ferrarini Carlo Corvaja Giovanni Zordan Gianfranco Scorrano Michele Maggini 《Liquid crystals》2002,29(2):203-208
A nitroxide [60]fullerene adduct containing a pyrrolidine-1-oxyl group has been synthesized. Its orientational order in the nematic phase of the liquid crystal solvent 4,4'-azoxyanisole (PAA) has been measured from the variation of the EPR spectral parameters on passing from the isotropic to the nematic phase. Highly resolved EPR lines allow for precise evaluation of the shifts of the g , a N and a H values. Since the g and the hyperfine tensors are known, the order matrix could be obtained. This is compared with the one calculated with a theoretical model based on short range solute-solvent interactions, which predicts a considerable degree of orientation of the molecular axes, despite the almost spherical shape of the molecule. The agreement with experimental findings is quite good and it is further improved if a bent structure of the pyrrolidine ring is taken into account. 相似文献
35.
In this Note we deal with the finite element approximation of a transmission problem across a prefractal curve approximating the von Koch fractal curve. We construct a mesh adapted to the geometric shape of the interface and we refine it consistently with some estimates in suitable weighted Sobolev spaces. In these spaces we also obtain an approximation error estimate. To cite this article: P. Bagnerini et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
36.
Inside Back Cover: Fragment‐Based Discovery of a Dual pan‐RET/VEGFR2 Kinase Inhibitor Optimized for Single‐Agent Polypharmacology (Angew. Chem. Int. Ed. 30/2015)
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37.
Dr. Annalisa Arcella Dr. Jens Dreyer Dr. Emiliano Ippoliti Ivan Ivani Dr. Guillem Portella Dr. Valérie Gabelica Prof. Dr. Paolo Carloni Prof. Dr. Modesto Orozco 《Angewandte Chemie (International ed. in English)》2015,54(2):467-471
By combining ion‐mobility mass spectrometry experiments with sub‐millisecond classical and ab initio molecular dynamics we fully characterized, for the first time, the dynamic ensemble of a model nucleic acid in the gas phase under electrospray ionization conditions. The studied oligonucleotide unfolds upon vaporization, loses memory of the solution structure, and explores true gas‐phase conformational space. Contrary to our original expectations, the oligonucleotide shows very rich dynamics in three different timescales (multi‐picosecond, nanosecond, and sub‐millisecond). The shorter timescale dynamics has a quantum mechanical nature and leads to changes in the covalent structure, whereas the other two are of classical origin. Overall, this study suggests that a re‐evaluation on our view of the physics of nucleic acids upon vaporization is needed. 相似文献
38.
39.
Donoli A Marcuzzo V Moretto A Toniolo C Cardena R Bisello A Santi S 《Organic letters》2011,13(6):1282-1285
Two series of 3(10)-helical peptides of different lengths and rigidity, based on the strongly foldameric α-aminoisobutyric acid and containing a terminal ferrocenyl unit, have been synthesized. Oxidation-state sensitive spectroscopic tags of helical peptides, the N-H groups, allowed mapping of the charge delocalization triggered by oxidation of the terminal ferrocenyl moiety and were monitored by IR spectroelectrochemistry. 相似文献
40.
Giovanni Petrillo Cinzia Tavani Lara Bianchi Alice Benzi Maria Maddalena Cavalluzzi Lara Salvagno Laura Quintieri Annalisa De Palma Leonardo Caputo Antonio Rosato Giovanni Lentini 《Molecules (Basel, Switzerland)》2021,26(13)
Twenty-two novel, variously substituted nitroazetidines were designed as both sulfonamide and urethane vinylogs possibly endowed with antimicrobial activity. The compounds under study were obtained following a general procedure recently developed, starting from 4-nitropentadienoates deriving from a common β-nitrothiophenic precursor. While being devoid of any activity against fungi and Gram-negative bacteria, most of the title compounds performed as potent antibacterial agents on Gram-positive bacteria (E. faecalis and three strains of S. aureus), with the most potent congener being the 1-(4-chlorobenzyl)-3-nitro-4-(p-tolyl)azetidine 22, which displayed potency close to that of norfloxacin, the reference antibiotic (minimum inhibitory concentration values 4 and 1–2 μg/mL, respectively). Since 22 combines a relatively efficient activity against Gram-positive bacteria and a cytotoxicity on eucharyotic cells only at 4-times higher concentrations (inhibiting concentration on 50% of the cultured eukaryotic cells: 36 ± 10 μM, MIC: 8.6 μM), it may be considered as a promising hit compound for the development of a new series of antibacterials selectively active on Gram-positive pathogens. The relatively concise synthetic route described herein, based on widely available starting materials, could feed further structure–activity relationship studies, thus allowing for the fine investigation and optimization of the toxico-pharmacological profile. 相似文献