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Celia?Ruiz-Palomero M.?Laura SorianoEmail author Miguel?Valcárcel 《Mikrochimica acta》2017,184(4):1069-1076
The paper reports on a method for the detection of nanocellulose (NC) in consumer products by making use of a combination of (a) liquid-liquid extraction with an ionic liquid, and (b) size characterization by asymmetric flow field-flow fractionation (AF4) coupled to multi-angle light scattering (MALS) and refractive index (RI) detection. Both AF4 and MALS are viable tools for characterizing the size of the nanofibers. Sample preparation is easy, and the extraction efficiency of the method is 80.9 ± 1.8% (n = 5). It was applied to the detection of NC in toothpaste and coconut foodstuff to verify the practicability of the method. 相似文献
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As a result of the increased focus on data literacy and data science across the world, there has been a large demand for professional development in statistics. However, exactly how these professional development opportunities should be structured remains an open question. The purpose of this paper is to describe the first iteration of a design experiment involving Project-SET (www.project-set.com) professional development program. Project-SET provided professional development to enhance teachers’ understanding of statistics concepts. The project constructed two learning trajectories for teacher learning and subsequently used the learning trajectories to structure the professional development curriculum. The main goal of this paper is to illustrate how the utilization of the teacher-learning trajectories to structure the professional development allowed participating teachers to develop several aspects of Statistics Knowledge for Teaching (Groth, 2013). 相似文献
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Sodiun borohydride reacts with oxazolidinium methiodides derived from ephedrine and pseudoephedrine, in ethereal solvents, cleaving regioselectively the C-N bond of the ring and leading, in good yields, to chiral amine-borane adducts of know absolute configuration. The 1HNMR data allow to predict the most stable conformation. 相似文献
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Experimental and Computational Studies of the Molybdenum‐Flanking Arene Interaction in Quadruply Bonded Dimolybdenum Complexes with Terphenyl Ligands 下载免费PDF全文
Dr. Mario Carrasco Irene Mendoza Dr. Eleuterio Álvarez Dr. Abdessamad Grirrane Dr. Celia Maya Dr. Riccardo Peloso Dr. Amor Rodríguez Andrés Falceto Prof. Dr. Santiago Álvarez Prof. Dr. Ernesto Carmona 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):410-421
To clarify the nature of the Mo?Carene interaction in terphenyl complexes with quadruple Mo?Mo bonds, ether adducts of composition [Mo2(Ar′)(I)(O2CR)2(OEt2)] have been prepared and characterized (Ar′=ArXyl2, R=Me; Ar′=ArMes2, R=Me; Ar′=ArXyl2, R=CF3) (Mes=mesityl; Xyl=2,6‐Me2C6H3, from now on xylyl) and their reactivity toward different neutral Lewis bases investigated. PMe3, P(OMe)3 and PiPr3 were chosen as P‐donors and the reactivity studies complemented with the use of the C‐donors CNXyl and CN2C2Me4 (1,3,4,5‐tetramethylimidazol‐2‐ylidene). New compounds of general formula [Mo2(Ar′)(I)(O2CR)2( L )] were obtained, except for the imidazol‐2‐ylidene ligand that yielded a salt‐like compound of composition [Mo2(ArXyl2)(O2CMe)2(CN2C2Me4)2]I. The Mo?Carene interaction in these complexes has been analyzed with the aid of X‐ray data and computational studies. This interaction compensates the coordinative and electronic unsaturation of one of the Mo atoms in the above complexes, but it seems to be weak in terms of sharing of electron density between the Mo and Carene atoms and appears to have no appreciable effect in the length of the Mo?Mo, Mo?X, and Mo? L bonds present in these molecules. 相似文献
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C Lanthony JM Ducéré MD Rouhani A Hemeryck A Estève C Rossi 《The Journal of chemical physics》2012,137(9):094707
We propose a barrierless mechanism for describing the oxidation of Al(111) in which oxygen atoms located on the outer surface extract aluminum atoms of the surface layers through local cooperation of other pre-adsorbed oxygen atoms. We show the details of this complex chemical process that kinetically competes with the non-destructive formation of an oxygen monolayer onto the Al surface, thus elucidating the initial aluminum oxidation regime. We demonstrate that further stripping of the complete surface Al layer is consistent with both (i) the formation of a defective alumina structure and (ii) an oxide capping layer preventing further oxidation at low temperature. 相似文献
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Rebeca Infante Dr. Javier Nieto Prof. Dr. Celia Andrés 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4375-4379
A highly efficient enantioselective addition of Me2Zn to α‐ketoesters, assisted by a chiral perhydro‐1,3‐benzoxazine ligand, is described. This novel catalytic system offers homogeneous elevated enantioselectivities in the preparation of α‐hydroxyesters that bear a quaternary stereocenter, with a minor dependence on electronic and steric effects when aromatic, heteroaromatic, or aliphatic α‐ketoesters are employed. The catalyst can be recovered and reused without loss of activity. 相似文献
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Crispín Cristóbal Dr. Yohar A. Hernández Dr. Joaquín López‐Serrano Prof. Dr. Margarita Paneque Dr. Ana Petronilho Prof. Dr. Manuel L. Poveda Dr. Verónica Salazar Florencia Vattier Dr. Eleuterio Álvarez Dr. Celia Maya Prof. Dr. Ernesto Carmona 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(12):4003-4020
The reactivity of a series of iridium? pyridylidene complexes with the formula [TpMe2Ir(C6H5)2(C(CH)3C(R)N H] ( 1 a – 1 c ) towards a variety of substrates, from small molecules, such as H2, O2, carbon oxides, and formaldehyde, to alkenes and alkynes, is described. Most of the observed reactivity is best explained by invoking 16 e? unsaturated [TpMe2Ir(phenyl)(pyridyl)] intermediates, which behave as internal frustrated Lewis pairs (FLPs). H2 is heterolytically split to give hydride? pyridylidene complexes, whilst CO, CO2, and H2C?O provide carbonyl, carbonate, and alkoxide species, respectively. Ethylene and propene form five‐membered metallacycles with an IrCH2CH(R)N (R=H, Me) motif, whereas, in contrast, acetylene affords four‐membered iridacycles with the IrC(?CH2)N moiety. C6H5(C?O)H and C6H5C?CH react with formation of Ir? C6H5 and Ir? C?CPh bonds and the concomitant elimination of a molecule of pyridine and benzene, respectively. Finally the reactivity of compounds 1 a – 1 c against O2 is described. Density functional theory calculations that provide theoretical support for these experimental observations are also reported. 相似文献