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961.
962.
963.
Iago Neira Dr. Cristina Alvariño Dr. Olaya Domarco Dr. Víctor Blanco Prof. Carlos Peinador Prof. Marcos D. García Prof. José M. Quintela 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(65):14834-14842
A series of aryl-extended N-monoalkyl-4,4′-bipyridinium salts L (aryl=1,4-phenyl, 4,4′-biphenyl, 2,6-naphthyl and 9,10-anthracenyl) have been implemented by PdII/PtII-directed self-assembly into constitutionally dynamic systems (CDSs). As a result, the intended processes produced not only (en) M 2 L 2 (en=ethylenediamine) metallacyclic species but also (en) M 4 L 4 ring-in-ring aggregates, in equilibrium with the former, as a consequence of the hydrophobic nature of the aryl rings within the 4,4′-bipyridinium scaffold. The key feature of the obtained dynamic systems is the possibility of modulating their response against external stimuli by modifying the hydrophobic character of the ligand. While the different dynamic libraries follow the same trends upon changes in concentration, temperature, polarity of the medium, or addition of an aromatic chemical effector, subtle changes in the ligand hydrophobic core results in a fine-tuning of the speciation when applying a certain degree of the different stimulus. The exception is the anthracene-containing derivative, which does not form inclusion complexes or self-threaded structures. 相似文献
964.
Systems of particles interacting with long range interactions present generically ”quasi-stationary states” (QSS), which are
approximately time-independent out of equilibrium states. In this proceedings, we explore the generalization of the formation
of such QSS and their relaxation from the much studied case of gravity to a generic pair interaction with the asymptotic form
of the potential v(r) ∼ 1/r
γ
with γ > 0 in d dimensions. We compute analytic estimations of the relaxation time calculating the rate of two body collisionality in a virialized
system approximated as homogeneous. We show that for γ < (d − 1/2), the collision integral is dominated by the size of the system, while for γ > (d − 1/2), it is dominated by small impact parameters. In addition, the lifetime of QSS increases with the number of particles
if γ < d − 1 (i.e. the force is not integrable) and decreases if γ > d − 1. Using numerical simulations we confirm our analytic results. A corollary of our work gives a ”dynamical” classification
of interactions: the dynamical properties of the system depend on whether the pair force is integrable or not. 相似文献
965.
Suélio Marques Marcos A. Castro Renato B. Pontes Salviano A. Leão Tertius L. Fonseca 《International journal of quantum chemistry》2020,120(3):e26093
This work reports the results of the vibrational corrections and frequency dependence to the first hyperpolarizabilities of the alkali- and alkaline-earth-doped boron nitride nanotubes. The electronic contributions were computed by means of the density functional theory with the M06-2X functional, and the vibrational corrections were calculated using the perturbation theoretical method and the field-induced coordinates methodology. The results for the electronic contribution show that such materials exhibit large first hyperpolarizabilities and electride characteristic. We also show that the distribution of the excess electron, which originates from the doping atoms, plays an important role in the large electronic hyperpolarizabilities (βel). Moreover, our findings strongly indicate that the effect of vibrations on the hyperpolarizabilities can be quite important and can even be much larger than the electronic counterpart. 相似文献
966.
This contribution proposes an approach for solving Reliability–based optimization (RBO) problems involving discrete design variables. The proposed approach is based on a decoupling approach and sequential approximations. An application example involving a linear structure under dynamic loading is presented, showing the efficiency of the proposed method. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
967.
Europium(III) Concentration Effect on the Spectroscopic and Photoluminescent Properties of BaMoO4:Eu
Ieda L. V. Rosa Ana Paula A. Marques Marcos T. S. Tanaka Fabiana V. Motta José A. Varela Edson R. Leite Elson Longo 《Journal of fluorescence》2009,19(3):495-500
BaMoO4:Eu (BEMO) powders were synthesized by the polymeric precursor method (PPM), heat treated at 800 °C for 2 h in a heating rate
of 5 °C/min and characterized by powder X-ray diffraction patterns (XRD), Fourier Transform Infra-Red (FTIR) and Raman spectroscopy,
besides room temperature Photoluminescence (PL) measurements. The emission spectra of BEMO samples under excitation of 394 nm
present the characteristic Eu3+ transitions. The relative intensities of the Eu3+ emissions increase as the concentration of this ion increases from 0.01 to 0.075 mol, but the luminescence is drastically
quenched for the Ba0.855Eu0.145MoO4 sample. The one exponential decay curves of the Eu3+ 5D0→7F2 transition, λ
exc = 394 nm and λ
em = 614 nm, provided the decay times of around 0.54 ms for all samples. It was observed a broadening of the Bragg reflections
and Raman bands when the Eu+3 concentration increases as a consequence of a more disordered material. The presence of MoO3 and Eu2Mo2O7 as additional phases in the BEMO samples where observed when the Eu3+ concentration was 14.5 mol%. 相似文献
968.
Simultaneous Determination of Glucose and Choline Based on the Intrinsic Fluorescence of the Enzymes
I. Sanz-Vicente J. J. Romero S. de Marcos M. Ostra C. Ubide J. Galbán 《Journal of fluorescence》2009,19(4):583-591
It has been possible to perform the simultaneous determination of choline and glucose using the intrinsic fluorescence of
the corresponding enzyme as an analytical signal. This can be done in two ways. First, for low glucose and choline concentrations
(about 0.55 mM and 0.75 μM respectively) two differentiated signals, without mutual interference, are obtained for both analytes
in the same measurement. Second, when glucose and choline concentrations are higher, a new model has been designed which permits
the concentrations to be accurately determined in samples containing from 0.55 mM to 3.75 mM glucose and from 0.75 μM to 11.0 μM
choline; the method has been applied to simultaneous glucose and choline determinations in serum samples with good results.
This method gives a better performance than multivariate calibration based on Partial Least Squares Regression. The methodology
here shown could be also used for the simultaneous determination of other pairs of analytes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
969.
A new strategy, epoxide-assisted precipitation route presented in this work, allows the shape control synthesis of Co3O4 nanoparticles. The shape of the nanoparticles is determined by the nature of the precursor cobalt salts (Co(NO3)2 · 6H2O, CoCl2 · 6H2O) used for the preparation of the particles. The different reaction dynamics of the two salts in ethanolic and aqueous solutions
with propylene oxide result in precursor particles with different structures, which lead to the formation of oxide nanoparticles
with different shapes during the heat treatment. Spherical particles of about 20 nm are obtained from the ethanolic solution
of Co(NO3)2 · 6H2O; cubic-shaped particles of about 30 nm can be prepared from the ethanolic solution of CoCl2 · 6H2O; whereas platelet-like particles of more than 100 nm are synthesized from the aqueous solution of the mixture of Co(NO3)2 · 6H2O and CoCl2 · 6H2O. 相似文献
970.