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661.
662.
Since the early 70s electrochemistry has been used as a powerful analytical technique for monitoring electroactive species in living organisms. In particular, after extremely rapid evolution of new micro and nanotechnology it has been established as an invaluable technique ranging from experiments in vivo to measurement of exocytosis during communication between cells under in vitro conditions. This review highlights recent advances in the development of electrochemical sensors for selective sensing of one of the most important neurotransmitters—dopamine. Dopamine is an electroactive catecholamine neurotransmitter, abundant in the mammalian central nervous system, affecting both cognitive and behavioral functions of living organisms. We have not attempted to cover a large time-span nor to be comprehensive in presenting the vast literature devoted to electrochemical dopamine sensing. Instead, we have focused on the last five years, describing recent progress as well as showing some problems and directions for future development. 相似文献
663.
Afewerki S Breistein P Pirttilä K Deiana L Dziedzic P Ibrahem I Córdova A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(32):8784-8788
Branching out! The first co-catalytic enantioselective (up to 98:2 e.r.) β-alkylation of α,β-unsaturated aldehydes by combination of simple chiral amine and copper catalysts provides β-branched aldehydes in a one-pot protocol. The methodology was applied to the short total syntheses of bisabolane sesquiterpenes (S)-(+)-curcumene, (E)-(S)-(+)-3-dehydrocurcumene and (S)-(+)-tumerone. 相似文献
664.
Deiana L Dziedzic P Zhao GL Vesely J Ibrahem I Rios R Sun J Córdova A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(28):7904-7917
The development, scope, and application of the highly enantioselective organocatalytic aziridination of α,β-unsaturated aldehydes is presented. The aminocatalytic azirdination of α,β-unsaturated aldehydes enables the asymmetric formation of β-formyl aziridines with up to >19:1 d.r. and 99% ee. The aminocatalytic aziridination of α-monosubstituted enals gives access to terminal α-substituted-α-formyl aziridines in high yields and up to 99% ee. In the case of the organocatalytic aziridination of disubstituted α,β-unsaturated aldehydes, the transformations were highly diastereo- and enantioselective and give nearly enantiomerically pure β-formyl-functionalized aziridine products (99% ee). A highly enantioselective one-pot cascade sequence based on the combination of asymmetric amine and N-heterocyclic carbene catalysis (AHCC) is also disclosed. This one-pot three-component co-catalytic transformation between α,β-unsaturated aldehydes, hydroxylamine derivatives, and alcohols gives the corresponding N-tert-butoxycarbonyl and N-carbobenzyloxy-protected β-amino acid esters with ee values ranging from 92-99%. The mechanisms and stereochemistry of all these catalytic transformations are also discussed. 相似文献
665.
We predict theoretically the optical signatures of spin polarization of carriers in self-assembled quantum dots. The emission spectra are mapped out as a function of increasing electron spin polarization for a fixed number of electrons and holes. The spin-polarized spectra are determined using exact diagonalization techniques for up to 12 particles, corresponding to two lowest filled shells. We predict that the spin polarization leads to photon polarization, to redshifts of emission lines due to excess exchange interactions among the spin-polarized electrons, and to a complete breakup of emission lines for spin-polarized electronic shells. 相似文献
666.
667.
Evaluation of the UFXC32k photon‐counting detector for pump–probe experiments using synchrotron radiation 下载免费PDF全文
Anna Koziol Michel Bordessoule Alessandra Ciavardini Arkadiusz Dawiec Paulo Da Silva Kewin Desjardins Pawel Grybos Brahim Kanoute Claire Laulhe Piotr Maj Claude Menneglier Pascal Mercere Fabienne Orsini Robert Szczygiel 《Journal of synchrotron radiation》2018,25(2):413-418
This paper presents the performance of a single‐photon‐counting hybrid pixel X‐ray detector with synchrotron radiation. The camera was evaluated with respect to time‐resolved experiments, namely pump–probe–probe experiments held at SOLEIL. The UFXC camera shows very good energy resolution of around 1.5 keV and allows the minimum threshold setting to be as low as 3 keV keeping the high‐count‐rate capabilities. Measurements of a synchrotron characteristic filling mode prove the proper separation of an isolated bunch of photons and the usability of the detector in time‐resolved experiments. 相似文献
668.
669.
Jacek Niziol Andrzej Danel Ewa Gondek Pawel Armatys Jerzy Sanetra Gisele Boiteux 《Macromolecular Symposia》2004,212(1):473-478
In this paper the synthesis of some new chromophores which could be used in polymer/organic LED fabrication are presented. All of them are pyrazoloquinoline (PAQ) derivatives. Their emission properties were tuned by side group substitution. They were characterized by absorption and photoemission spectroscopy. Some were used, dispersed in poly(N-vinylcarbazole) (PVK) matrix, as the emissive layer in LED structures. 相似文献