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排序方式: 共有330条查询结果,搜索用时 15 毫秒
1.
Rodríguez-Calvillo Pablo Ferrer Nuria Cabrera José-María 《Journal of Thermal Analysis and Calorimetry》2021,146(3):1393-1403
Journal of Thermal Analysis and Calorimetry - The thermal behavior of two copper alloys, with 0.2 and 0.5 mass % of Mg, was analyzed after severe plastic deformation processing by Equal Channel... 相似文献
2.
Dr. Antonio Sánchez-Ruiz Dr. Julián Rodríguez-López Dr. Andrés Garzón-Ruiz Dr. Sonia B. Jiménez-Pulido Dr. Nuria A. Illán-Cabeza Dr. Amparo Navarro Dr. Joaquín C. García-Martínez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(61):13990-14001
Different molecular strategies have been carefully evaluated to produce solid-state luminescence enhancement (SLE) in compounds that show dark states in solution. A set of α-phenylstyrylarene derivatives with a butterfly shape have been designed and synthesised, for the first time, with the aim of improving the solid-state fluorescence emission of their parent styrylarene compounds. Although these butterfly molecules are not fluorescent in solution, one of them (1,2,4,5-tetra(α-phenylstyryl)benzene) exhibits a fluorescence quantum yield as high as 68 % in a drop-cast sample and 31 % in its crystalline form. In contrast, 1,3,5-tris(α-phenylstyryl)benzene and 4,6-bis(α-phenylstyryl)pyrimidine do not show SLE. A range of fluorescence spectroscopy experiments and DFT calculations were carried out to unravel the origin of different photophysical behaviour of these compounds in the solid state. The results indicate that a rational strategy to control the SLE effect in luminogens depends on a delicate balance between molecular properties and inter-/intramolecular interactions in the solid state. 相似文献
3.
Luis Fermín Capitán-Vallvey Nuria López-Ruiz Antonio Martínez-Olmos Miguel M. Erenas Alberto J. Palma 《Analytica chimica acta》2015
Chemical analysis based on colour changes recorded with imaging devices is gaining increasing interest. This is due to its several significant advantages, such as simplicity of use, and the fact that it is easily combinable with portable and widely distributed imaging devices, resulting in friendly analytical procedures in many areas that demand out-of-lab applications for in situ and real-time monitoring. This tutorial review covers computer vision-based analytical (CVAC) procedures and systems from 2005 to 2015, a period of time when 87.5% of the papers on this topic were published. The background regarding colour spaces and recent analytical system architectures of interest in analytical chemistry is presented in the form of a tutorial. Moreover, issues regarding images, such as the influence of illuminants, and the most relevant techniques for processing and analysing digital images are addressed. Some of the most relevant applications are then detailed, highlighting their main characteristics. Finally, our opinion about future perspectives is discussed. 相似文献
4.
Direct chemical profiling of olive (Olea europaea) fruit epicuticular waxes by direct electrospray‐ultrahigh resolution mass spectrometry 下载免费PDF全文
Stefania Vichi Nuria Cortés‐Francisco Agustí Romero Josep Caixach 《Journal of mass spectrometry : JMS》2015,50(3):558-566
In the present paper, an electrospray ionization (ESI)‐Orbitrap method is proposed for the direct chemical profiling of epicuticular wax (EW) from Olea europaea fruit. It constitutes a rapid and efficient tool suitable for a wide‐ranging screening of a large number of samples. In a few minutes, the method provides a comprehensive characterization of total EW extracts, based on the molecular formula of their components. Accurate mass measurements are obtained by ultrahigh resolution mass spectrometry, and compositional restrictions are set on the basis of the information available from previous studies of olive EW. By alternating positive and negative ESI modes within the same analysis, complementary results are obtained and a wide range of chemical species is covered. This provides a detailed compositional overview that otherwise would only be available by applying multiple analytical techniques. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
Dihydrogen Catalysis of the Reversible Formation and Cleavage of CH and NH Bonds of Aminopyridinate Ligands Bound to (η5‐C5Me5)IrIII 下载免费PDF全文
Dr. Ana Zamorano Dr. Nuria Rendón Dr. Joaquín López‐Serrano Dr. José E. V. Valpuesta Dr. Eleuterio Álvarez Prof. Dr. Ernesto Carmona 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2576-2587
This study focuses on a series of cationic complexes of iridium that contain aminopyridinate (Ap) ligands bound to an (η5‐C5Me5)IrIII fragment. The new complexes have the chemical composition [Ir(Ap)(η5‐C5Me5)]+, exist in the form of two isomers ( 1+ and 2+ ) and were isolated as salts of the BArF? anion (BArF=B[3,5‐(CF3)2C6H3]4). Four Ap ligands that differ in the nature of their bulky aryl substituents at the amido nitrogen atom and pyridinic ring were employed. In the presence of H2, the electrophilicity of the IrIII centre of these complexes allows for a reversible prototropic rearrangement that changes the nature and coordination mode of the aminopyridinate ligand between the well‐known κ2‐N,N′‐bidentate binding in 1+ and the unprecedented κ‐N,η3‐pseudo‐allyl‐coordination mode in isomers 2+ through activation of a benzylic C?H bond and formal proton transfer to the amido nitrogen atom. Experimental and computational studies evidence that the overall rearrangement, which entails reversible formation and cleavage of H?H, C?H and N?H bonds, is catalysed by dihydrogen under homogeneous conditions. 相似文献
6.
Javier Alcaraz Nuria RamónJosé L. Ruiz Inmaculada Sirvent 《European Journal of Operational Research》2013
The existence of alternate optima for the DEA weights may reduce the usefulness of the cross-efficiency evaluation, since the ranking provided depends on the choice of weights that the different DMUs make. In this paper, we develop a procedure to carry out the cross-efficiency evaluation without the need to make any specific choice of DEA weights. The proposed procedure takes into consideration all the possible choices of weights that all the DMUs can make, and yields for each unit a range for its possible rankings instead of a single ranking. This range is determined by the best and the worst rankings that would result in the best and the worst scenarios of each unit across all the DEA weights of all the DMUs. This approach might identify good/bad performers, as those that rank at the top/bottom irrespective of the weights that are chosen, or units that outperform others in all the scenarios. In addition, it may be used to analyze the stability of the ranking provided by the standard cross-efficiency evaluation. 相似文献
7.
Jorge Castellanos-Soriano Allen T. Ekubo Mark R. J. Elsegood Nuria Lastra-Calvo Aman Mantry Arturo Martinez-Insua-Rodriguez 《Phosphorus, sulfur, and silicon and the related elements》2017,192(5):570-575
New tetraalkylaminophosphonium chlorides were readily prepared by four-fold condensation of commercially available [P(CH2OH)4]Cl with a range of fifteen aryl based primary amines, in EtOH, at ambient temperature. All compounds have been characterized by FT–IR spectroscopy and elemental analysis. Solution 31P{1H} NMR studies of these chloride salts reveal their instability with respect to various PIII/PV species. The structures of three examples have been determined by single crystal X-ray diffraction and confirm the pseudotetrahedral arrangement around the PV center. Extensive N–H···Cl hydrogen bonding is observed. 相似文献
8.
Virginia Cebrián Clara Yagüe Manuel Arruebo Francisco M. Martín-Saavedra Jesus Santamaría Nuria Vilaboa 《Journal of nanoparticle research》2011,13(9):4097-4108
Mesoporous silica nanoparticles have been synthesized and functionalized with four different types of molecules containing
amino groups, i.e., with primary amines only, with quaternary amines, with quaternized cyclic amines, or with polyethylenimine
(PEI), which is formed by primary, secondary, and tertiary amines. These nanoparticles were then incubated with reporter plasmids
and the ability of the resulting complexes to transfect human cells was studied. Only nanoparticles functionalized with PEI
were efficient for transfection. The agglomeration behavior and the electrokinetic potential of the nanoparticle–plasmid complexes
have been studied, as well as their cell internalization behavior using a fluorescent-labeled plasmid that allows its monitorization
by confocal microscopy. The results indicate that the efficiency of PEI-functionalized nanoparticles for transfection resides
to some extent in the different characteristics imparted to the nanoparticles regarding agglomeration and surface charge behavior. 相似文献
9.
The influence of large amplitude pairing fluctuations is investigated in the framework of beyond mean field symmetry conserving configuration mixing calculations. In the numerical application the finite range density dependent Gogny force is used. We investigate the nucleus 54Cr with particle number and angular momentum projected wave functions considering the axial quadrupole deformation and the pairing gap degree of freedom as generator coordinates. We find that the effects of the pairing fluctuations increase with the excitation energy and the angular momentum. The self-consistency in the determination of the basis states plays an important role. 相似文献
10.