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201.
202.
Kpers Verena Kolek Martin Bieker Peter Stan Marian Cristian Placke Tobias Winter Martin 《Journal of Solid State Electrochemistry》2022,26(9):2077-2088
Journal of Solid State Electrochemistry - In this work, a cell concept comprising of an anion intercalating graphite-based positive electrode (cathode) and an elemental sulfur-based negative... 相似文献
203.
204.
Cristian Peptu Oscar F. van den Brink Valeria Harabagiu Bogdan C. Simionescu Marek Kowalczuk Jerzy Silberring 《Journal of polymer science. Part A, Polymer chemistry》2012,50(12):2421-2431
End‐capped and intramolecular azofunctional oligocaprolactones were characterized at molecular level by liquid chromatography electrospray ionization mass spectrometry (ESI MS) and NMR spectroscopy. The Disperse Red 19 (DR19) azofunctional oligomers, DC, were synthesized by ring‐opening oligomerization of ε‐caprolactone (ε‐CL) initiated by the hydroxyl groups of DR19 azo dye. The reaction products consist of a minor fraction of end‐capped azo functional oligocaprolactone (α‐DC), that is, a single CL arm oligomer, and a major fraction of intramolecular azo functional oligocaprolactone (β‐DC), that is, a two CL arms oligomer. The chromatographic separation was used to discriminate between α‐DC and β‐DC, and the results were confirmed by MS/MS performed on an ESI ion trap instrument. The results supported by accurate mass data obtained for product ions using an ESI quadrupole time of flight instrument demonstrate the qualitative discrimination at the molecular level between intramolecular and end‐capped azofunctional oligoesters isomers through a relatively simple multistage mass spectrometry experiment. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
205.
206.
A green alternative method for analysis of ivermectin and moxidectin in environmental water samples using automatized preconcentration previous MEEKC
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Emiliano Felici Cristian Casado Chien C. Wang Julio Raba María R. Gomez 《Electrophoresis》2016,37(22):2977-2985
Antiparasitic drugs derived from macrocyclic lactones (MLs) are widely used in livestock activities around the world. An increasing concern for local authorities is the environmental pollution as a consequence of veterinary drugs widely used in rural areas. The purpose of environmental analysis is to monitor low levels of pollutant analytes in a large number of samples. Also, due to the lipophilic characteristic of these lactones, long‐chain solvents are usually required for performing sample treatment before and during the analysis. Therefore, sensitive, specific, robust, and environmentally friendly analytical methods are still required. In this paper, a new automatized preconcentration methodology followed by microemulsion electrokinetic chromatography analysis was developed for the simultaneous separation and determination of the most used MLs, ivermectin (IVM) and moxidectin (MXD) in environmental water. XAD‐4 resin was employed as an adsorbent for the preconcentration process and ethanol was used as the eluent. In contrast to traditional analysis for IVM and MXD, in this methodology nonpolluting solvents were involved during the whole process and therefore, it could be considered as a contribution to green analytical chemistry. Under optimal experimental conditions, LOD obtained for IVM and MXD were of 3 × 10?3 and 3.6 × 10?3 μg/L, respectively. 相似文献
207.
The Baeyer‐Villiger oxidation versus aromatic ring hydroxylation: competing organic peracid oxidation mechanisms explored by multivariate modelling of designed multi‐response experiments
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Peroxy acids can be used as the terminal oxidant for the Baeyer–Villiger oxidation of acetophenones and for direct ring hydroxylation of methoxy‐substituted benzenes. An oxidative system involving 3‐chloroperbenzoic acid (mCPBA) and 2,6‐dimethoxyacetophenone as model substrate was investigated by means of statistical experimental design, multivariate modelling and response surface methodology. The outcome of the organic peracid oxidation experiments was portrayed by a multi‐response matrix consisting of the yields of three different compounds; 2,6‐dimethoxyphenyl acetate, 1‐(4‐hydroxy‐2,6‐dimethoxy‐phenyl)ethanone and 3‐hydroxy‐2,6‐dimethoxy‐phenyl acetate. The optimized reaction protocol was utilized to investigate a series of various substituted acetophenones. The overall investigation revealed that both the molecular structure of the acetophenone substrate and the experimental conditions exhibited a substantial impact on whether the oxidation reaction follows the oxygen insertion or direct ring hydroxylation mechanism. An improved protocol for the direct ring hydroxylation was also obtained from the experimental and modelling described herein. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
208.
Cristian Paz Viviana Burgos Sebastin Suarez Ricardo Baggio 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(4):294-297
The title compound, dendocarbin A [systematic name: (1R,5aS,9aS,9bR)‐1‐hydroxy‐6,6,9a‐trimethyldodecahydronaphtho[1,2‐c]furan‐3‐one], C15H22O3, is a sesquiterpene lactone isolated from Drimys winteri var chilensis. The monoclinic phase described herein displays an identical molecular structure to the orthorhombic phase that we reported previously [Paz Robles et al. (2014). Acta Cryst. C 70 , 1007–1010], while varying significantly in chain pitch, and can thus be considered as a borderline case of one‐dimensional isostructural polymorphism. 相似文献
209.
In this paper, a novel 3D nonlinear system with chaotic behavior is considered. Our proposed system is a generalized Lorenz‐like system, with no reflections about coordinates axes. Although the considered system depends on seven real parameters, its stability is completely analyzed. Also, the presence of Hopf bifurcation is pointed out. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
210.
Electrospray ionization (ESI) of the Lindqvist (n-Bu4N)2[M6O19] (M = Mo, W) polyoxometalates provides a straightforward entry for the generation of an assortment of oxo- and hydroxo anions
in the gas-phase. In particular, the series of oxo dianions of general formula [(MO3)
n
O]2− (n = 2–6; M = Mo, W), monoanions, namely [(MO3)
n
O]− (n = 1, 2) and [(MO3)
n
]− (n = 1, 2), and the hydroxo [(MO3)
n
(OH)]− (n = 1–6) species can be readily generated in the gas-phase upon varying the solvent composition as well as the ionisation conditions
(typically the Uc cone voltage). Complementary tandem mass experiments (collision induced dissociation and ion–molecule reactions) are also
used aimed to investigate the consecutive dissociation of these species and their intrinsic gas-phase reactivity towards methanol.
Special emphasis is paid to some of the key factors of these group 6 anions related to the gas-phase activation of methanol,
such as molecular composition, open vs closed shell electronic nature and cluster size. 相似文献