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241.
Ultra-High Performance Concrete (UHPC) that contains pyrogenic oxides (Pox) and has been heat-cured with microwave energy reaches as high as 420 MPa after 1 day. The influence of microwave curing on the strength gain is much more pronounced in UHPC than in normal concrete. 29Si and 27Al MAS NMR nanomolecular structure investigation of Ultra-High-Performance Concrete (UHPC) modified with nanoscale pozzolans (pyrogenic oxides) reveals significant differences from other concrete types that may explain such high early strength. There is an increase in polymerization degree of C-(A) S–H (C–S–H containing Al) phase of the UHPC modified with pyrogenic oxides, followed by a trend of substitution of silicon atoms on the Q? sites of C–S–H (calcium-silicate-hydrates) through aluminum atoms. The mean chain length (MCL) and degree of connectivity (Dc) are the highest for pyrogenic oxides containing UHPC that have been cured with microwave energy. The increase of polymerization degree is more pronounced for alumina-based pyrogenic oxide containing UHPC. 相似文献
242.
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244.
Cáceres Gustavo Rojas Víctor López Silvana Henríquez Rodrigo Grez Paula Schrebler Ricardo Herrera Francisco Pereyra C. Javier Marotti Ricardo E. Navarrete Emilio Muñoz Eduardo 《Journal of Solid State Electrochemistry》2021,25(6):1881-1888
Journal of Solid State Electrochemistry - In this work, the influence of the electrochemical insertion of different alkali ions, e.g., lithium, sodium, and potassium, on the electrochromic... 相似文献
245.
Yang Ding Carlos M. Gutirrez‐Ariza C. IgnacioSainz‐Díaz Julyan H. E. Cartwright Silvana S. S. Cardoso 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6273-6279
Chemical gardens and clock reactions are two of the best‐known demonstration reactions in chemistry. Until now these have been separate categories. We have discovered that a chemical garden confined to two dimensions is a clock reaction involving a phase change, so that after a reproducible and controllable induction period it explodes. 相似文献
246.
Rolf Brandl Silvana Franciosi Francesco De Giovanni 《Rendiconti del Circolo Matematico di Palermo》1999,48(1):13-22
IfH is a subgroup of a groupG, theautomizer ofH inG is the group of all automorphisms ofH induced by elements of its normalizerN
G
(H). the subgroupH is said to havesmall automizer ifAut
G
(H)=Inn(H), i.e. ifN
G
(H)=HC
G
(H). This article is devoted to the study of groups for which many subgroups have small automizer.
In Memoriam Valeria Fedri
R. Brandl wishes to express his sincerest thanks for the warm hospitality offered by the Department of Mathematics of the
University of Napoli “Federico II” for the time of writing this paper. 相似文献
247.
Sofía Raffaelli Eduardo Abreo Nora Altier lvaro Vzquez Silvana Albors 《Molecules (Basel, Switzerland)》2022,27(6)
Antimicrobial resistance is a growing concern in public health and current research shows an important role for bacterial biofilms in recurrent or chronic infections. New strategies, therefore, are necessary to overcome antimicrobial resistance, through the development of new therapies that could alter or inhibit biofilm formation. In this sense, antibiofilm natural products are very promising. In this work, a bioprospection of antimicrobial and antibiofilm extracts from Uruguayan soil bacteria and insect gut bacteria was carried out. Extracts from extracellular broths were tested for their ability to inhibit planktonic cell growth and biofilm formation. Genomic analysis of Bacillus cereus ILBB55 was carried out. All extracts were able to inhibit the growth of, at least, one microorganism and several extracts showed MICs lower than 500 µg mL−1 against microorganisms of clinical relevance (Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacter cloacae). Among the extracts evaluated for biofilm inhibition only ILBB55, from B. cereus, was able to inhibit, S. aureus (99%) and P. aeruginosa (62%) biofilms. Genomic analysis of this strain showed gene clusters similar to other clusters that code for known antimicrobial compounds. Our study revealed that extracts from soil bacteria and insect gut bacteria, especially from B. cereus ILBB55, could be potential candidates for drug discovery to treat infectious diseases and inhibit S. aureus and P. aeruginosa biofilms. 相似文献
248.
Arlen Ferrari Massimo Merlin Silvana Sostero Heinz Rüegger LuigiM. Venanzi 《Helvetica chimica acta》1999,82(9):1454-1457
The photochemical rearrangement of [Rh(η4-1,5-cod)TpMe2](TpMe2=hydrotris(3,5-dimethylpyrazolyl)borato, 1,5-cod=cycloocta-1,5-diene) to the new compound [Rh(η4-1,3-cod)TpMe2] ( 2 ) is described. The characterization of 2 was carried out using 1H-, 13C-, and 103Rh-HMQC-NMR spectroscopy. Photolysis of 2 is a versatile entry point into the organometallic chemistry of the {RhTpMe2} fragment as it can be used to produce a) hydrido-carbonyl ([Rh(CO)H2TpMe2]), b) hydrido-phenyl-phosphite ([RhH(Ph)(P(OMe)3)TpMe2]), and c) ethoxide-hydrido-phosphite ([RhH(OEt)(P(OMe)3)TpMe2]) complexes. 相似文献
249.
Arlen Ferrari Massimo Merlin Silvana Sostero Orazio Traverso Heinz Rüegger Luigi M. Venanzi 《Helvetica chimica acta》1998,81(11):2127-2139
Photolysis of [Ir(η2-coe)H2(TpMe2)] ( 1 ; TpMe2=hydrotris(3,5-dimethylpyrazolyl)borato, coe=(Z)-cyclooctene) in CH3OH gives a mixture of [IrH4(TpMe2)] ( 4 ) and [Ir(CO)H2(TpMe2)] ( 5 ) in a ca. 1 : 1 ratio. Mass-spectral analysis of the distillate of the reaction mixture at the end of the photolysis shows the presence of coe. When pure CD3OD is used as solvent, the deuteride complexes [IrD4(TpMe2)] ((D4)- 4 ) and [Ir(CO)D2(TpMe2)] ((D2)- 5 ) are obtained. Also the photolysis of [Ir(η4-cod)(TpMe2)] ( 3 ) (cod=cycloocta-1,5-diene) gives 4 and 5 . A key feature of this photoreaction is the intramolecular dehydrogenation of cod with formation of cycloocta-1,3,5-triene, detected by mass spectroscopy at the end of the photolysis. Labeling experiments using CD3OD show that the hydrides in 4 originate from MeOH. When 13CH3OH is used as solvent, [Ir(13CO)H2(TpMe2)] is formed demonstrating that CH3OH is the source of the CO ligand. The observation that the photolysis of both 1 and 3 give the same product mixture is attributed to the formation of a common intermediate, i.e., the coordinatively unsaturated 16e− species {IrH2(TpMe2)}. 相似文献
250.
Domenico La Camera Vittorio Petraccone Silvana Artimagnella Odda Ruiz de Ballesteros 《Macromolecular Symposia》2001,166(1):157-164
The influence of the shape and size of guest molecules on the structural organization of the α and β class clathrates of syndiotactic poly(p‐methylstyrene) is described, through the analysis of the packing model proposed for the crystal structures of the clathrate forms containing o‐dichlorobenzene and tetrahydrofuran. Preliminary data of the crystal structure of the s‐PPMS clathrate containing benzene and a comparison with the crystal structure of the clathrate forms of syndiotactic polystyrene are also presented. 相似文献