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71.
Systems of strongly coupled chaotic maps generically exhibit collective behavior emerging out of extensive chaos. We show how the well-known renormalization group (RG) of unimodal maps can be extended to the coupled systems, and in particular to coupled map lattices (CMLs) with local diffusive coupling. The RG relation derived for CMLs is nonperturbative, i.e., not restricted to a particular class of configurations nor to some vanishingly small region of parameter space. After defining the strong-coupling limit in which the RG applies to almost all asymptotic solutions, we first present the simple case of coupled tent maps. We then turn to the general case of unimodal maps coupled by diffusive coupling operators satisfying basic properties, extending the formal approach developed by Collet and Eckmann for single maps. We finally discuss and illustrate the general consequences of the RG: CMLs are shown to share universal properties in the space-continuous limit which emerges naturally as the group is iterated. We prove that the scaling properly ties of the local map carry to the coupled systems, with an additional scaling factor of length scales implied by the synchronous updating of these dynamical systems. This explains various scaling laws and self-similar features previously observed numerically. 相似文献
72.
73.
Francesco Gentile Michael Fernandez Fuqiang Ban Anh-Tien Ton Hazem Mslati Carl F. Perez Eric Leblanc Jean Charle Yaacoub James Gleave Abraham Stern Bill Wong Franois Jean Natalie Strynadka Artem Cherkasov 《Chemical science》2021,12(48):15960
Recent explosive growth of ‘make-on-demand’ chemical libraries brought unprecedented opportunities but also significant challenges to the field of computer-aided drug discovery. To address this expansion of the accessible chemical universe, molecular docking needs to accurately rank billions of chemical structures, calling for the development of automated hit-selecting protocols to minimize human intervention and error. Herein, we report the development of an artificial intelligence-driven virtual screening pipeline that utilizes Deep Docking with Autodock GPU, Glide SP, FRED, ICM and QuickVina2 programs to screen 40 billion molecules against SARS-CoV-2 main protease (Mpro). This campaign returned a significant number of experimentally confirmed inhibitors of Mpro enzyme, and also enabled to benchmark the performance of twenty-eight hit-selecting strategies of various degrees of stringency and automation. These findings provide new starting scaffolds for hit-to-lead optimization campaigns against Mpro and encourage the development of fully automated end-to-end drug discovery protocols integrating machine learning and human expertise.Deep learning-accelerated docking coupled with computational hit selection strategies enable the identification of inhibitors for the SARS-CoV-2 main protease from a chemical library of 40 billion small molecules. 相似文献
74.
75.
Thirteen phases are now evidenced in the composition space diagram of the Al(OH)3–tren–HF–ethanol system at 190 °C. Solvothermal syntheses are performed under microwave heating. Six new organic–inorganic fluorides crystallise and their structures are determined: (H3O)·[H4tren]2·(AlF6)3·6H2O (P-1, Z = 2), [H3tren]2·(AlF5(H2O))3·8H2O (C2/c, Z = 8), [H3tren]4·(AlF6)2·(Al2F11)·(F)·10H2O (P21/n, Z = 2), [H3tren]2·(Al4F18)·3.5H2O (P63, Z = 2), [H3tren]2·(Al4F18) (P-1, Z = 1), and [H3tren]4·(Al8F35)·(OH)·H2O (P-1, Z = 1). The existence domains are approximately located for all phases. Tren amine is tetraprotonated at high HF concentration, otherwise it is triprotonated. A protonated water cluster, H3O+(H2O)6, appears in (H3O)·[H4tren]2·(AlF6)3·6H2O while a new Al4F18 unit, found in [H3tren]2·(Al4F18), is evidenced; it results from corner and edge sharing association of four AlF6 octahedra. Finally, the structure of [H3tren]4·(Al8F35)·(OH)·H2O revealed the largest known fluoroaluminate polyanion, built from eight vertex sharing AlF6 octahedra, (Al8F35)11−. 相似文献
76.
Amor Ben Ali Jean-Marc Grenche Marc Leblanc Vincent Maisonneuve 《Solid State Sciences》2009,11(9):1631-1638
The hydrothermal synthesis, using tris-(2-ethylamino)amine (tren) as a template, and the crystal structures of three new hybrid iron fluorides, (H3O)2·[H3tren]2·(FeF6)2·(FeF5(H2O))·2H2O (I), [H3tren]2·(FeF6)2·(FeF2(H2O)4)·8H2O (II) and [H3tren]2·(FeF6)·(F)3·H2O (III), are reported. I, II, and III are triclinic (P-1), monoclinic (P21/c) and orthorhombic (I222), respectively. The structure of I is built up from isolated FeF6 and FeF5(H2O) distorted octahedra separated by triprotonated [H3tren]3+ cations, disordered H3O+ cations and H2O molecules. In II, FeIIIF6 and neutral [FeIIF2(H2O)4] octahedra form, together with [H3tren]3+ cations, infinite (100) layers separated by extra water molecules. The structure of III consists of isolated and disordered FeF6 octahedra, fluoride anions F− connected to [H3tren]3+ cations and extra fluoride anions F− disordered with H2O molecules. All [H3tren]3+ cations have a “spider” type conformation. 57Fe Mössbauer characterization shows that +III valence state can only be considered for iron cations in I and III and preliminary Mössbauer results are consistent with the presence of both +II and +III valences for iron cations in II, in agreement with the crystallographic results. 相似文献
77.
Bughin C Zhao G Bienaymé H Zhu J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(4):1174-1184
A conceptually novel macrolactonization protocol has been developed. It is a domino process involving a sequence of: 1) protonation of 5-aminooxazole leading to the electrophilic iminium salt; 2) trapping of the iminium species by the neighboring C-terminal carboxylic acid leading to a putative spirolactone; and 3) intramolecular nucleophilic addition of the tethered alcohol to the spirolactone followed by fragmentation. The strategically incorporated 5-aminooxazole serves as an internal traceless activator of the neighboring C-terminal carboxylic acid, since it became an integral part of the peptide backbone after cyclization. No coupling reagent is required and the entire sequence is triggered by just a few equivalents of trifluoroacetic acid under very mild conditions (MeCN as the solvent at room temperature). The spirolactone as an activated form of the carboxylic acid has been evidenced by a sulfur-migration experiment. By combining with a three-component synthesis of 5-aminooxazole, a two-step synthesis of structurally complex cyclodepsipeptides from readily accessible starting materials was developed. 相似文献
78.
Ji X Naistat D Li C Orbulesco J Leblanc RM 《Colloids and surfaces. B, Biointerfaces》2006,50(2):104-111
Aβ (31–35) peptide and control peptides as well as full length Aβ (1–40) and Aβ (1–42) peptides were labelled with luminescent CdSe/ZnS quantum dots (QDs) to observe the morphology of amyloid fibers. A comparison was made between QDs and an organic dye, namely Dansyl group, which showed that the QDs present a much better contrast for imaging than the organic dye. 相似文献
79.
Moreno MJ Pacheco-Arjona J Rodríguez-González P Preud'Homme H Amouroux D Donard OF 《Journal of mass spectrometry : JMS》2006,41(11):1491-1497
In this work, the simultaneous determination of four organometallic species (monomethylmercury, monobutyltin, dibutyltin and tributyltin) in environmental samples by using a GC-MS system with electron ionisation has been established. The measurement of isotope ratios in each species was accomplished by selecting the most adequate molecular cluster, and simple mathematical equations were applied to correct the contributions of 13C from the organic groups attached to the tin and mercury atoms. The influence of different parameters such as dwell time on the precision and accuracy of the measured isotope ratios in each target species has also been studied. The determination and the sample preparation procedures presented in this work were first individually validated by analysing several certified reference materials for butyltin compounds (mussel tissue CRM-477 and marine sediment SOPH-1) and for monomethylmercury (tuna fish CRM-464) using an innovative focused microwave technology for the extraction of the species from the solid samples. Additionally, the simultaneous determination of the four species was successfully validated by obtaining quantitative recoveries in spiked natural waters and by analysing the certified reference material BCR-710 (certified in tributyltin and monomethylmercury). The values obtained in such certified tissue were fully in agreement not only with the certified mass fractions but also with the proposed indicative values for mono- and dibutyltin. 相似文献
80.
We report the synthesis and first characterization of N-alkyldiaminoresorcinols (or 4,6-bis-dialkylaminobenzene-1,3-diols C6H2(NHR)2(OH)2) (10a, R = CH2-2-Py; 10b, R = CH2-3-Py; 10c, R = CH2-4-Py) which result from one-pot stepwise reactions: (i) air-oxidation of diaminoresorcinol 3, (ii) transamination reaction leading to the corresponding functional 6π+6π quinonemonoimine zwitterions C6H2(NHR)2(O)2 (9a, R = CH2-2-Py; 9b, R = CH2-3-Py; 9c, R = CH2-4-Py), (iii) reduction and re-aromatization in the presence of the corresponding primary amine bearing a pyridine moiety. 相似文献