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51.
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Ermilas Alcalde Javier De Mendoza Jos Elguero Juan Marino Garcia-Marquina Consuelo Almera 《Journal of heterocyclic chemistry》1974,11(3):423-429
The three compounds C8 H10N4 which arise from reaction of hydrazine and β-aminocrotonitrile have been identified: the formation of anazine, a 3(5)-amino 5(3)-methyl pyrazole derivative and a 7-amino pyrazolo [1,5-a] pyrimidine has been demonstrated. The relationships among these compounds and with the methyl-aminopyrazole have been studied. 相似文献
53.
D. Mendoza J.L. Benítez F. Morales R. Escudero 《Solid State Communications》2010,150(25-26):1124-1127
Synthesis, electrical and magnetic characterization of a superconducting FeSe0.85 compound is reported. An anomaly in the magnetization against temperature around 90 K is observed. The magnetic characterization of a commercial compound with nominal FeSe stoichiometry is also presented. The overall magnetic behaviors as well as the magnetic anomaly in both compounds are discussed in terms of magnetic impurities and secondary phases. 相似文献
54.
The vehicle routing problem with stochastic demands consists in designing transportation routes of minimal expected cost to satisfy a set of customers with random demands of known probability distributions. This paper proposes a simple yet effective heuristic approach that uses randomized heuristics for the traveling salesman problem, a tour partitioning procedure, and a set partitioning formulation to sample the solution space and find high-quality solutions for the problem. Computational experiments on benchmark instances from the literature show that the proposed approach is competitive with the state-of-the-art algorithm for the problem in terms of both accuracy and efficiency. In experiments conducted on a set of 40 instances, the proposed approach unveiled four new best-known solutions (BKSs) and matched another 24. For the remaining 12 instances, the heuristic reported average gaps with respect to the BKS ranging from 0.69 to 0.15 % depending on its configuration. 相似文献
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Israel Rocha‐Mendoza Paola Borri Wolfgang Langbein 《Journal of Raman spectroscopy : JRS》2013,44(2):255-261
We demonstrate a technique for simultaneous detection of coherent anti‐Stokes Raman scattering (CARS) at four vibrational frequencies, using simple passive optical elements and without spectrally resolved detection. The technique is based on pump and Stokes femtosecond pulses selectively exciting vibrational resonances through spectral focusing. By replicating the pump and Stokes pair into four pairs, each traveling through appropriate glass elements, we simultaneously excite four different vibrational frequencies. The resulting CARS is a periodic train of intensities detected by a single photomultiplier and frequency analyzed to retrieve its Fourier coefficients. We demonstrate detection of methanol and ethanol mixtures in water and quantitative determination of their concentration owing to the improved chemical selectivity of this quadruplex CARS scheme. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Etienne Boutin Min Wang John C. Lin Matthieu Mesnage Daniela Mendoza Benedikt Lassalle‐Kaiser Christopher Hahn Thomas F. Jaramillo Marc Robert 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16318-16322
Conversion of CO2 into valuable molecules is a field of intensive investigation with the aim of developing scalable technologies for making fuels using renewable energy sources. While electrochemical reduction into CO and formate are approaching industrial maturity, a current challenge is obtaining more reduced products like methanol. However, literature on the matter is scarce, and even more for the use of molecular catalysts. Here, we demonstrate that cobalt phthalocyanine, a well‐known catalyst for the electrochemical conversion of CO2 to CO, can also catalyze the reaction from CO2 or CO to methanol in aqueous electrolytes at ambient conditions of temperature and pressure. The studies identify formaldehyde as a key intermediate and an unexpected pH effect on selectivity. This paves the way for establishing a sequential process where CO2 is first converted to CO which is subsequently used as a reactant to produce methanol. Under ideal conditions, the reaction shows a global Faradaic efficiency of 19.5 % and chemical selectivity of 7.5 %. 相似文献
59.
Chemically and Biologically Harmless versus Harmful Ferritin/Copper–Metallothionein Couples
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Dr. Fernando Carmona Daniela Mendoza Scheghajegh Kord Michela Asperti Prof. Paolo Arosio Prof. Sílvia Atrian Prof. Mercè Capdevila Prof. Jose M. Dominguez‐Vera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):808-813
The simultaneous measurement of the decrease of available FeII ions and the increase of available FeIII ions allowed the analysis of the ferroxidase activity of two distinct apoferritins. Although recombinant human apoferritin (HuFtH) rapidly oxidizes FeII to FeIII, this iron is not properly stored in the ferritin cavity, as otherwise occurs in horse‐spleen H/L‐apoferritin (HsFt; H=heavy subunit, L=light subunit). Iron storage in these apoferritins was also studied in the presence of two copper‐loaded mammalian metallothioneins (MT2 and MT3), a scenario that occurs in different brain‐cell types. For HuFtH, unstored FeIII ions trigger the oxidation of Cu–MT2 with concomitant CuI release. In contrast, there is no reaction with Cu–MT2 in the case of HsFt. Similarly, Cu–MT3 does not react during either HuFtH or HsFt iron reconstitution. Significantly, the combination of ferritin and metallothionein isoforms reported in glia and neuronal cells are precisely those combinations that avoid a harmful release of FeII and CuI ions. 相似文献
60.
The existence of a homoclinic orbit in dynamical systems implies chaotic behaviour with positive entropy. In this work, we determine explicitly the Markov shifts associated to certain Smale horseshoe homoclinic orbits which allow us to compute a lower bound for the topological entropy that such a system can have. It is done associating a heteroclinic orbit which belongs to the same isotopy class and then determining the Markov partition of the dynamical core of an end periodic mapping. 相似文献