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961.
Understanding Complex Electrochemical Impedance Spectroscopy in Corrosion Systems Using in‐situ Synchrotron Radiation Grazing Incidence X‐ray Diffraction
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Muhammad Tanzirul Alam Emilyn Wai Lyn Chan Roland De Marco Yanliang Huang Stuart Bailey 《Electroanalysis》2016,28(9):2166-2170
The difficulty in interpreting electrochemical impedance spectroscopy (EIS) data has limited the potential of the method despite its utility as an electrochemical method for studies of electrode reactions and interfacial structures. Taking the test case of the carbon dioxide corrosion of carbon steel, in‐situ synchrotron radiation grazing incidence X‐ray diffraction (SR‐GIXRD) has been demonstrated to be a powerful technique for validating and understanding the interfacial structures associated with complex EIS data. Carbon dioxide corrosion was found to occur in several steps, which may only be surmised by EIS, but the use of SR‐GIXRD in conjunction with EIS has enabled the establishment of a link between EIS time constants and structural changes associated with the evolution of corrosion products with time. By comparison to previous studies by the authors and others in this field, this communication provides the first direct experimental evidence linking SR‐GIXRD surface compositional data to otherwise indistinctive EIS time constants. 相似文献
962.
The Role of Ligand Topology in the Decomplexation of Luminescent Lanthanide Complexes by Dipicolinic Acid
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Dr. Federica Mian Dr. Gregorio Bottaro Dr. Roberta Seraglia Dr. Marco Cavazzini Dr. Silvio Quici Prof. Lidia Armelao 《Chemphyschem》2016,17(20):3229-3236
In this study, we present the aqueous solution behavior of two luminescent lanthanide antenna complexes (Eu3+? 1 , Dy3+? 9 ) with different ligand topologies in the presence of dipicolinic acid (DPA, pyridine‐2,6‐dicarboxylic acid). Macrocyclic (1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid, DO3A, 9 ) and acyclic (1,4,7‐triazaheptane‐1,1,7,7‐tetraacetic acid, DTTA, 1 ) ligands have been selected to form a ratiometric pair in which Dy3+? 9 acts as a reference and Eu3+? 1 acts as a probe for the recognition of DPA. The pair of luminescent complexes in water reveals the capability to work as a DPA luminescent sensor. The change of emission intensity of Eu3+ indicates the occurrence of a new sensitization path for the lanthanide cation through excitation of DPA. NMR evidence implies the presence of free 1 and mass spectrometry shows the formation of emitting [EuDPA2]? as a result of a ligand exchange reaction. 相似文献
963.
Marco A. S. Trindade Eric Pinto J. D. M. Vianna 《Advances in Applied Clifford Algebras》2016,26(2):771-792
The aim of this paper is to present a general algebraic formulation for the decoherence-free subspaces (DFSs). In order to build the DFSs we consider the tensor product of Clifford algebras and left minimal ideals. States, error operators and projection operators are defined in a purely algebraic point of view. For this purpose, we initially generalize some results of Pauli and Artin about semisimple algebras. Then we derive orthogonality theorems for associative algebras analogous to theorems for finite groups. Some advantages and perspectives are also discussed. 相似文献
964.
Tiago Carvalho Marco Antônio Teixeira Durval José Tonon 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2016,67(2):31
The paper deals with the analysis of the behavior of a nonsmooth three-dimensional vector field around a typal singularity. We focus on a class of generic one-parameter families \({Z_{\lambda}}\) of Filippov systems and address the persistence problem for the asymptotic stability when the parameter varies near the bifurcation value \({\lambda = 0}\). 相似文献
965.
In the present work we investigate various optical properties (such as light absorption and reflectance) of anodic TiO2 nanotube layers directly transferred as self‐standing membranes onto quartz substrates. This allows investigation in a transmission geometry which provides significantly more reliable data than measurements on the metallic Ti substrate. Light transmission and reflectance measurements were carried out for layers of thickness varying from 1.8 to 50 μm, and the layers were investigated in their amorphous and crystalline forms. A series of wavelength‐dependent light attenuation coefficients are extrapolated and found to match the photocurrent versus irradiation wavelength behavior. A feature specific to anodic nanotubes is that their intrinsic carbon contamination content causes a proportional sub‐bandgap response. Overall, the extracted data provide a valuable basis and understanding for the design of photo‐electrochemical devices based on TiO2 nanotubes. 相似文献
966.
A graph is reflexive if the second largest eigenvalue of its adjacency matrix is less than or equal to 2. In this paper, we characterize trees whose line graphs are reflexive. It turns out that these trees can be of arbitrary order—they can have either a unique vertex of arbitrary degree or pendant paths of arbitrary lengths, or both. Since the reflexive line graphs are Salem graphs, we also relate some of our results to the Salem (graph) numbers. 相似文献
967.
We wish to describe here that good levels of substrate-based, 1,5-syn-stereocontrol could be achieved in the boron-mediated aldol reactions of beta-trichloromethyl methylketones with achiral aldehydes, independent of the nature of the beta-alkoxy protecting group. 相似文献
968.
[reaction: see text] A stereocontrolled, convergent synthesis of the alkaloid australine, a glycosidase inhibitor of the pyrrolizidine class, is described. The chiral starting materials were ketone 3, derived from L-erythrulose, and alpha-alkoxy aldehyde 4, prepared from L-malic acid. A key step of the synthesis was the highly stereoselective aldol reaction between 4 and a Z boron enolate derived from 3. Another key step was the one-pot construction of the bicyclic pyrrolizidine system by means of a three-step sequence of SN2 displacements induced by benzylamine on a trimesylate precursor. 相似文献
969.
[reaction: see text] The enantioselective total synthesis of proansamitocin, a key biosynthetic intermediate of the highly potent antitumor agent ansamitocin P-3, is described which bears a diene-ene RCM as the key macrocyclization step. Feeding of proansamitocin to an AHBA block mutant Actinosynnema pretiosum (HGF073) yielded ansamitocin P-3 as well as dechloroansamitocin P-3, the latter also being formed upon fermentation in the presence of 3-amino-5-methoxybenzoic acid. 相似文献
970.