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131.
Piovezan C Silva JM Neves A Bortoluzzi AJ Haase W Tomkowicz Z Castellano EE Hough TC Rossi LM 《Inorganic chemistry》2012,51(11):6104-6115
Presented herein is the design of a dinuclear Ni(II) synthetic hydrolase [Ni(2)(HBPPAMFF)(μ-OAc)(2)(H(2)O)]BPh(4) (1) (H(2)BPPAMFF = 2-[(N-benzyl-N-2-pyridylmethylamine)]-4-methyl-6-[N-(2-pyridylmethyl)aminomethyl)])-4-methyl-6-formylphenol) to be covalently attached to silica surfaces, while maintaining its catalytic activity. An aldehyde-containing ligand (H(2)BPPAMFF) provides a reactive functional group that can serve as a cross-linking group to bind the complex to an organoalkoxysilane and later to the silica surfaces or directly to amino-modified surfaces. The dinuclear Ni(II) complex covalently attached to the silica surfaces was fully characterized by different techniques. The catalytic turnover number (k(cat)) of the immobilized Ni(II)Ni(II) catalyst in the hydrolysis of 2,4-bis(dinitrophenyl)phosphate is comparable to the homogeneous reaction; however, the catalyst interaction with the support enhanced the substrate to complex association constant, and consequently, the catalytic efficiency (E = k(cat)/K(M)) and the supported catalyst can be reused for subsequent diester hydrolysis reactions. 相似文献
132.
Catarina I. V. Ramos M. Graça Santana‐Marques A. J. Ferrer‐Correia Joana F. B. Barata Augusto C. Tomé M. Graça P. M. S. Neves J. A. S. Cavaleiro Paulo E. Abreu Mariette M. Pereira Alberto A. C. C. Pais 《Journal of mass spectrometry : JMS》2012,47(4):516-522
Two new isomeric aminomethyl corrole derivatives of [5,10,15‐tris(pentafluorophenyl)corrolato]gallium(III) were synthesized with pyridine (py) molecules as axial ligands. When investigated by electrospray ionization mass spectrometry, in the positive and the negative ion modes, these compounds showed an unusual gas‐phase behavior that could be used for their differentiation. In the positive ion mode, the differentiation was achieved through the formation of diagnostic fragment ions formed from [M‐py + H]+ precursors, by (CH3)2NH and HF losses. An unusual addition of water to the main fragment ions provides an alternative route for isomer identification. Semi‐empirical calculations were performed to elucidate the structures and stabilities of the main ionic species formed in the positive ion mode. In the negative ion mode isomer discrimination is accomplished via the fragmentation of the methoxide adduct ions [M‐py + CH3O]‐ through (CH3)2 N. and HF losses. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
133.
Grazziela P. Figueredo Nelson F. F. Ebecken Douglas A. Augusto Helio J. C. Barbosa 《Memetic Computing》2012,4(2):135-147
One issue in data classification problems is to find an optimal subset of instances to train a classifier. Training sets that
represent well the characteristics of each class have better chances to build a successful predictor. There are cases where
data are redundant or take large amounts of computing time in the learning process. To overcome this issue, instance selection
techniques have been proposed. These techniques remove examples from the data set so that classifiers are built faster and,
in some cases, with better accuracy. Some of these techniques are based on nearest neighbors, ordered removal, random sampling
and evolutionary methods. The weaknesses of these methods generally involve lack of accuracy, overfitting, lack of robustness
when the data set size increases and high complexity. This work proposes a simple and fast immune-inspired suppressive algorithm
for instance selection, called SeleSup. According to self-regulation mechanisms, those cells unable to neutralize danger tend
to disappear from the organism. Therefore, by analogy, data not relevant to the learning of a classifier are eliminated from
the training process. The proposed method was compared with three important instance selection algorithms on a number of data
sets. The experiments showed that our mechanism substantially reduces the data set size and is accurate and robust, specially
on larger data sets. 相似文献
134.
It is shown that for Gaussian diffusions, the transformation back to Brownian motion, usually accomplished via the Girsanov (or Feynman–Kac) formula and time-shift, can be obtained by a classical canonical, i.e. symplectic, transformation in phase space. The method is based on constants of motion, in this case the Wronskian. Similar transformations for general diffusions are briefly discussed. 相似文献
135.
Joo Victor Batista da Silva Carlos Augusto Fernandes de Oliveira Leandra Nira Zambelli Ramalho 《Molecules (Basel, Switzerland)》2021,26(23)
Aflatoxins are mycotoxins produced as secondary fungal metabolites. Among them, aflatoxin B1 (AFB1) stands out due to its genotoxic and mutagenic potential, being a potent initiator of carcinogenesis. In this review, the outcomes from the published literature in the past 10 years on the effects of AFB1 pathophysiological mechanisms on embryological and fetal development are discussed. In several animal species, including humans, AFB1 has a teratogenic effect, resulting in bone malformations, visceral anomalies, lesions in several organs, and behavioral and reproductive changes, in addition to low birth weight. The mutagenic capacity of AFB1 in prenatal life is greater than in adults, indicating that when exposure occurs in the womb, the risk of the development of neoplasms is higher. Studies conducted in humans indicate that the exposure to this mycotoxin during pregnancy is associated with low birth weight, decreased head circumference, and DNA hypermethylation. However, as the actual impacts on humans are still unclear, the importance of this issue cannot be overemphasized and studies on the matter are essential. 相似文献
136.
Takembo Clovis Ntahkie Mvogo Alain Fouda H. P. Ekobena Kofane T. C. 《Nonlinear dynamics》2019,95(2):1079-1098
Nonlinear Dynamics - Motivated by often non-observance clinical effects attributed to some pathological heart diseases, we obtain in this paper the analytical solutions describing localized... 相似文献
137.
Dr. G. Henrieke Heideman Dr. José Augusto Berrocal Prof. Meike Stöhr Prof. E. W. Meijer Prof. Ben L. Feringa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):207-211
The development of new strategies for the preparation of multicomponent supramolecular assemblies is a major challenge on the road to complex functional molecular systems. Here we present the use of a non-porous self-assembled monolayer from uC33-NDI-uC33 , a naphthalenediimide symmetrically functionalized with unsaturated 33 carbon-atom-chains, to prepare bicomponent supramolecular surface systems with a series of alkoxy-pyrene ( PyrOR ) derivatives at the liquid/HOPG interface. While previous attempts at directly depositing many of these PyrOR units at the liquid/HOPG interface failed, the multicomponent approach through the uC33-NDI-uC33 template enabled control over molecular interactions and facilitated adsorption. The PyrOR deposition restructured the initial uC33-NDI-uC33 monolayer, causing an expansion in two dimensions to accommodate the guests. As far as we know, this represents the first example of a non-porous or non-metal complex-bearing monolayer that allows the stepwise formation of multicomponent supramolecular architectures on surfaces. 相似文献
138.
139.
An inequality reminiscent of Kato’s inequality is presented. Motivated by this, we discuss some criteria to decide whether
a singularity of the equation Δu=g in Ω/K comes from a Radon measure or not. As an application, we extend a lemma of H. Brezis and P. L. Lions on isolated singularities
to the case where the singularity lies on a compact manifold.
this author was supported by CAPES, Brazil, under the grant BEX 1187/99-6. 相似文献
140.
When extended supergravity theories with noncompact symmetry groups are written in a physical gauge, the noncompact symmetries join with the supersymmetries to generate an infinite-dimensional algebra. The details are worked out explicitly for a two-dimensional theory with an SU(1, 1) internal symmetry. Our analysis confirms the observation of Ellis et al. that the infinite rigid superalgebra should be obtained from the finite-dimensional local superalgebra by replacing scalar fields with their asymptotic values at infinity. The infinite algebra is described by extending the super-Poincaré generators to functions on the coset space defined by the scalar fields at infinity. While mathematically nontrivial, this result is, in a certain sense, trivial from a physical point of view. 相似文献