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81.
Xiao-Lei Li Lang Zhao Jianfeng Wu Wei Shi Niklas Struch Arne Lützen Annie K. Powell Peng Cheng Jinkui Tang 《Chemical science》2022,13(34):10048
In situ metal-templated (hydrazone) condensation also called subcomponent self-assembly of 4,6-dihydrazino-pyrimidine, o-vanillin and dysprosium ions resulted in the formation of discrete hexa- or dodecanuclear metallosupramolecular Dy6(L)6 or Dy12(L)8 aggregates resulting from second-order template effects of the base and the lanthanide counterions used in these processes. XRD analysis revealed unique circular helical or tetragonal bipyramid architectures in which the bis(hydrazone) ligand L adopts different conformations and shows remarkable differences in its mode of metal coordination. While a molecule of trimethylamine acts as a secondary template that fills the void of the Dy6(L)6 assembly, sodium ions take on this role for the formation of heterobimetallic Dy12(L)8 by occupying vacant coordination sites, thus demonstrating that these processes can be steered in different directions upon subtle changes of reaction conditions. Furthermore, Dy6(L)6 shows an interesting spin-relaxation energy barrier of 435 K, which is amongst the largest values within multinuclear lanthanide single-molecular magnets.Subcomponent self-assembly gave access to Dy12(L)8 and Dy6(L)6 architectures via second-order template effects. The Dy6(L)6 assembly behaves as a single-molecule magnet exhibiting a high anisotropy barrier and butterfly-shaped magnetic hysteresis. 相似文献
82.
Rouven F. Pfleger Sören Schlittenhardt Dr. Marcel P. Merkel Prof. Dr. Mario Ruben Prof. Dr. Karin Fink Dr. Christopher E. Anson Prof. Jesper Bendix Prof. Dr. Annie K. Powell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(61):15086-15095
We report three structurally related single ion Dy compounds using the pentadentate ligand 2,6-bis((E)-1-(2-(pyridin-2-yl)-hydrazineylidene)ethyl)pyridine (H2dapp) [Dy(H2dapp)(NO3)2]NO3 ( 1 ), [Dy(H2dapp)(OAc)2]Cl ( 2 ) and [Dy(H2dapp)(NO3)2]Cl0.92(NO3)0.08 ( 3 ). The (H2dapp) occupies a helical twisted pentagonal equatorial arrangement with two anionic ligands in the axial positions. Further influence on the electronic and magnetic structure is provided by a closely associated counterion interacting with the central N−H group of the (H2dapp). The slow relaxation of the magnetisation shows that the anionic acetates give the greatest slowing down of the magnetisation reversal. Further influence on the relaxation properties of compounds 1 and 2 is the presence of short nitrate-nitrate intermolecular ligand contact opening further lattice relaxation pathways. 相似文献
83.
84.
Efficacy of cidofovir injection for the treatment of recurrent respiratory papillomatosis 总被引:4,自引:0,他引:4
To evaluate the efficacy of intralesional cidofovir injection for the treatment of recurrent respiratory papillomatosis (RRP). It is a prospective, open-label study design. This prospective study included 16 RRP patients, ages 9 to 68 years, who were treated with intralesional injections of cidofovir combined with surgical excision of RRP. The disease states of the patients pretreatment and posttreatment were assessed by assigning RRP severity scores, examining the need for any surgical excision of RRP, and evaluating the presence of RRP upon long-term follow-up. Sixteen patients were treated with cidofovir; however, three were lost to follow-up. Thirteen patients are the subjects of this report. This study group included three pediatric patients. Ten of thirteen patients (76.9%) responded to the treatment and are presently in remission. One patient did not respond, and two patients relapsed after initial success or had a partial response. The responders consisted of eight adults and two children. The mean number of injections the responders received was 3.5, and the average follow-up period of the responders was 25.4 months. No immediate complication of cidofovir treatment was evident. However, three patients were found to have significant vocal fold scarring after long-term follow-up. Cidofovir has been found to be efficacious in treating RRP. Further study regarding long-term follow-up and the assessment of possible side effects after cidofovir intralesional injection for RRP is required. 相似文献
85.
Summary Padé approximants are a frequently used tool for the solution of mathematical problems. One of the main drawbacks of their use for multivariate functions is the calculation of the derivatives off(x
1, ...,x
p
). Therefore multivariate Newton-Padé approximants are introduced; their computation will only use the value off at some points. In Sect. 1 we shall repeat the univariate Newton-Padé approximation problem which is a rational Hermite interpolation problem. In Sect. 2 we sketch some problems that can arise when dealing with multivariate interpolation. In Sect. 3 we define multivariate divided differences and prove some lemmas that will be useful tools for the introduction of multivariate Newton-Padé approximants in Sect. 4. A numerical example is given in Sect. 5, together with the proof that forp=1 the classical Newton-Padé approximants for a univariate function are obtained. 相似文献
86.
87.
88.
Annie Millet 《Mathematische Zeitschrift》1980,172(3):213-237
Sans résumé 相似文献
89.
The well-known cleavage reactions of vicinal diols by such reagents as Pb(OAc)4, NaIO4, PhI(OAc)2 and Ph3BiV-compounds have now been observed for the first time on covalent derivatives of these vicinal diols, their dibutylstannylenes. 相似文献
90.
Annie Alexander Selden 《Semigroup Forum》1976,12(1):373-379