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51.
Re‐Appearance of Cooperativity in Ultra‐Small Spin‐Crossover [Fe(pz){Ni(CN)4}] Nanoparticles
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Haonan Peng Dr. Simon Tricard Gautier Félix Dr. Gábor Molnár Dr. William Nicolazzi Dr. Lionel Salmon Dr. Azzedine Bousseksou 《Angewandte Chemie (International ed. in English)》2014,53(41):10894-10898
A reverse nanoemulsion technique was used for the elaboration of [Fe(pz){Ni(CN)4}] nanoparticles. Low‐temperature micellar exchange made it possible to elaborate ultra‐small nanoparticles with sizes down to 2 nm. When decreasing the size of the particles from 110 to 12 nm the spin transition shifts to lower temperatures, becomes gradual, and the hysteresis shrinks. On the other hand, a re‐opening of the hysteresis was observed for smaller (2 nm) particles. A detailed 57Fe Mössbauer spectroscopy analysis was used to correlate this unusual phenomenon to the modification of the stiffness of the nanoparticles thanks to the determination of their Debye temperature. 相似文献
52.
Massoumi Sina Challamel Noël Lerbet Jean Wautier Antoine Nicot François Darve Félix 《Meccanica》2022,57(8):2043-2066
Meccanica - This study is an attempt towards a better understanding of the length scale effects on the bending response of the granular beams. To this aim, a unidimensional discrete granular chain... 相似文献
53.
Dr. Flávio Figueira Igor Marques Dr. Andreia S. F. Farinha Prof. Dr. Augusto C. Tomé Prof. Dr. José A. S. Cavaleiro Prof. Dr. Artur M. S. Silva Prof. Dr. Jonathan Sessler Prof. Dr. Vítor Félix Prof. Dr. João P. C. Tomé 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14349-14355
A novel sapphyrin derivative was obtained from the reaction between a free‐base sapphyrin and dimethyl acetylenedicarboxylate (DMAD). The formation of the new compound involved a double aza‐Michael addition of two pyrrolic NH groups to a DMAD molecule, with the formation of a disubstituted ethano bridge. The NMR spectral data reveal a product with an unsymmetrical structure; DFT calculations provided support for a structure in which the ethano bridge links two adjacent pyrrole units. The present study provides a seemingly unprecedented example of an N,N′‐dinucleophile reacting with DMAD to form a heterocyclic compound in which the two N‐atoms are linked to the two sp3 carbon atoms derived from a substituted acetylene. 相似文献
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56.
Félix Cabello Sánchez 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》1999,69(1):167-173
We deal with mappings from a (not necessarily commutative) groupG into a Banach spaceY which are nearly additive in the sense of satisfying that for some constantK ≥ 0,
wheneverx
i
andy
i
∈ G are such that Σ
i=1
n
x
i
= Σ
j=1
m
y
j
,where P ’ is a fixed (non-negative) ”control” functional onG. Such maps, called zero-additive, appear in various contexts. The smallest constantK for which the inequality holds shall be noted byZ(F).
For mappingsG’ Y we consider the (possibly infinite) distance
Then one may ask whether or not a zero-additive mapF must be near to a true additive mapA : G → Y in the sense of dist(F, A) < ∞ and howZ(F) and dist(F, A) are related (a question which goes back to Ulam). We prove the following “uniform boundedness” result, thus solving a problem
stated by CASTILLO and the present author.
This work is supported in part by DGICYT project PB97-0377 and HI project 1997-0016. 相似文献
57.
Basurto S Torroba T Comes M Martínez-Máñez R Sancenón F Villaescusa L Amorós P 《Organic letters》2005,7(24):5469-5472
[structure: see text] A new sensory MCM-41-based material for the colorimetric sensing and discrimination of amines has been developed. 相似文献
58.
Thin films of barium strontium titanate (Ba1−xSrx TiO3 (BSTO)) have been used in coupled microstrip phase shifters (CMPS) for possible insertion in satellite and wireless communication platforms primarily because of their high dielectric constant, low loss, large tunability, and good structural stability. In an attempt to improve the figure of merit K (phase shift °/dB of loss) of phase shifters, modification of the metal/BSTO interface of these devices has been done through surface modification of the BSTO layer using a self-assembled monolayer approach. The impact of this nanotechnology promises to reduce RF losses by improving the quality of the metal/BSTO interface. In this study, compounds such as 3-mercaptopropyltrimethoxysilane (MPS), 16-mercaptohexadecanois acid (MHDA) and 3-mercaptopropionic acid (MPA) were used to form the self-assembled monolayers on the BSTO surface. As a result of the previous modification, chemical derivatization of the self-assembled monolayers was done in order to increase the chain length. Chemical derivatization was done using 3-aminopropyltrimethoxysilane (APS) and 16-mercaptohexadecanoic acid. Surface chemical analysis was done to reveal the composition of the derivatization via X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared (FT-IR). Low and high frequencies measurements of phase shifters were done in order measure the performance of these devices for insertion in antennas. X-ray photoelectron spectroscopy characterization of modified BSTO thin films with MPS showed a binding energy peak at 162.9 eV, indicative of a possible SO interaction: sulfur of the mercapto compound, MPS, used to modify the surface with the oxygen site of the BSTO thin film. This interaction is at higher binding energies compared with the thiolate interaction. This behavior is observed with the other mercapto compounds such as: MHDA and MPA. An FT-IR analysis present a band at 780 cm−1, which is characteristic of an OSC stretching and reveals the modification of the BSTO thin film by the coupling of the O of the BSTO with the S of the mercapto compound. All the modification using mercapto compounds is through sulfur to the BSTO thin film. MHDA SAM on BSTO thin film was chemically derivatized using APS shown by XPS and FT-IR. The SAMs modified phase shifters showed an improvement in performance with respect to those phase shifters fabricated with standard methods. 相似文献
59.
Yves Fé lix Jean-Claude Thomas 《Proceedings of the American Mathematical Society》2004,132(1):305-312
Let be a simply-connected closed oriented -dimensional manifold. We prove that for any field of coefficients there exists a natural homomorphism of commutative graded algebras where is the loop algebra defined by Chas and Sullivan. As usual denotes the monoid of self-equivalences homotopic to the identity, and the space of based loops. When is of characteristic zero, yields isomorphisms where denotes the Hodge decomposition on .
60.
[reaction: see text] Highly stereoselective titanium-mediated aldol reactions based on lactate-derived ketones are reported. The stereochemical outcome of the process depends on the protecting group (PMB or Bn) and the Lewis acid (i-PrOTiCl(3) or TiCl(4)) used in the enolization step, the corresponding anti-syn or syn-syn aldols being prepared in high yields and with diastereomeric ratios up to 99:1. 相似文献