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31.
Elise Deunf Olivier Buriez Eric Labbé Jean-Noël Verpeaux Christian Amatore 《Electrochemistry communications》2009,11(1):114-117
The electrochemical behavior of a new cobalt–cyclodextrin (CD) complex was investigated, in dimethylformamide, from CoX2 (X = Br and BF4) in the presence of 1 equiv. 6-Deoxy-6-N-(2-methyliminopyridine)-β-cyclodextrin as ligand. Under these conditions, it was demonstrated for the first time, that the electrogenerated cobalt(I) species can be kinetically and thermodynamically stabilized. The electrochemical study of CoX2 in the presence of a related iminopyridine ligand (2-pyridyl-N-benzylmethylimine), in which the cyclodextrin (CD) group was replaced by a simple aryl moiety, allowed to highlight the crucial role of the CD in this unexpected stabilization. Importantly, this unprecedented result was only observed when both the iminepyridine and the CD moieties were together covalently attached. Importantly, the supramolecular stabilized low-valent cobalt species remained fairly reactive towards aromatic halides despite its intrinsic stability. This original work opens new opportunities for the development of more selective catalytic processes both in organic and aqueous media. 相似文献
32.
Joshi HM Lin YP Aslam M Prasad PV Schultz-Sikma EA Edelman R Meade T Dravid VP 《The journal of physical chemistry. C, Nanomaterials and interfaces》2009,113(41):17761-17767
Cobalt ferrite magnetic nanostructures were synthesized via a high temperature solution phase method. Spherical nanostructures of various sizes were synthesized with the help of seed mediated growth of the nanostructures in organic phase, while faceted irregular (FI) cobalt ferrite nanostructures were synthesized via the same method but in the presence of a magnetic field. Magnetic properties were characterized by SQUID magnetometry, relaxivity measurements and thermal activation under RF field, as a function of size and shape. The results show that the saturation magnetization of the nanostructures increases with an increase in size, and the FI nanostructures exhibit lower saturation magnetization than their spherical counterparts. The relaxivity coefficient of cobalt ferrite nanostructures increases with increase in size; while FI nanostructures show a higher relaxivity coefficient than spherical nanostructures with respect to their saturation magnetization. In the case of RF thermal activation, the specific absorption rate (SAR) of nanostructures increases with increase in the size. The contribution sheds light on the role of size and shape on important magnetic properties of the nanostructures in relation to their biomedical applications. 相似文献
33.
The photodissociation dynamics of small I-(H2O)n(n=2-5) clusters excited to their charge-transfer-to-solvent (CTTS) states have been studied using photofragment coincidence imaging. Upon excitation to the CTTS state, two photodissociation channels were observed. The major channel (approximately 90%) is a two-body process forming neutral I+(H2O)n photofragments, and the minor channel is a three-body process forming I+(H2O)n-1+H2O fragments. Both processes display translational energy [P(ET)] distributions peaking at ET=0 with little available energy partitioned into translation. Clusters excited to the detachment continuum rather than to the CTTS state display the same two channels with similar P(ET) distributions. The observation of similar P(ET) distributions from the two sets of experiments suggests that in the CTTS experiments, I atom loss occurs after autodetachment of the excited [I(H2O)n-]* cluster or, less probably, that the presence of the excess electron has little effect on the departing I atom. 相似文献
34.
Elise A. Dennis Steven J. Ray Christie G. Enke Alexander W. Gundlach-Graham Charles J. Barinaga David W. Koppenaal Gary M. Hieftje 《Journal of the American Society for Mass Spectrometry》2016,27(3):371-379
Distance-of-flight mass spectrometry (DOFMS) is demonstrated for the first time with a commercially available ion detector—the IonCCD camera. Because DOFMS is a velocity-based MS technique that provides spatially dispersive, simultaneous mass spectrometry, a position-sensitive ion detector is needed for mass-spectral collection. The IonCCD camera is a 5.1-cm long, 1-D array that is capable of simultaneous, multichannel ion detection along a focal plane, which makes it an attractive option for DOFMS. In the current study, the IonCCD camera is evaluated for DOFMS with an inductively coupled plasma (ICP) ionization source over a relatively short field-free mass-separation distance of 25.3–30.4 cm. The combination of ICP-DOFMS and the IonCCD detector results in a mass-spectral resolving power (FWHM) of approximately 900 and isotope-ratio precision equivalent to or slightly better than current ICP-TOFMS systems. The measured isotope-ratio precision in % relative standard deviation (%RSD) was ≥0.008%RSD for nonconsecutive isotopes at 10-ppm concentration (near the ion-signal saturation point) and ≥0.02%RSD for all isotopes at 1-ppm. Results of DOFMS with the IonCCD camera are also compared with those of two previously characterized detection setups. 相似文献
35.
36.
Ozcan Altintas Thierry Muller Elise Lejeune Oliver Plietzsch Stefan Brse Christopher Barner‐Kowollik 《Macromolecular rapid communications》2012,33(11):977-983
A well‐defined random copolymer of styrene (S) and chloromethylstyrene (CMS) featuring lateral chlorine moieties with an alkyne terminal group is prepared (P(S‐co‐CMS), = 5500 Da, PDI = 1.13). The chloromethyl groups are converted into Hamilton wedge (HW) entities (P(S‐co‐HWS), = 6200 Da, PDI = 1.13). The P(S‐co‐HWS) polymer is subsequently ligated with tetrakis(4‐azidophenyl)methane to give HW‐functional star‐shaped macromolecules (P(S‐co‐HWS))4, = 25 100 Da, PDI = 1.08). Supramolecular star‐shaped copolymers are then prepared via self‐assembly between the HW‐functionalized four‐arm star‐shaped macromolecules ( P(S‐co‐HW )) 4 and cyanuric acid (CA) end‐functionalized PS (PS–CA, = 3700 Da, PDI = 1.04), CA end‐functionalized poly(methyl methacrylate) (PMMA–CA, = 8500 Da, PDI = 1.13) and CA end‐functionalized polyethylene glycol (PEG–CA, = 1700 Da, PDI = 1.05). The self‐assembly is monitored by 1H NMR spectroscopy and light scattering analyses. 相似文献
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39.
Yoko Hirohara Toshifumi Mihashi Asaki Suzaki Teruhito Kuroda Jennifer Elise Kelly Naoyuki Maeda Takashi Fujikado 《Optical Review》2006,13(5):396-404
To assess optical characteristics of bifocal soft contact lenses (BCLs) in use, we measured wavefront aberrations of human
eyes, of eyes with a monofocal soft contact lens (MCL), and of eyes with a BCL. Modulation transfer functions (MTFs), Strehl
ratios, and simulated images for far and near vision were produced with the measured aberrations. High order aberrations of
subject 1 were significantly smaller than those of subject 2 (t-test, P = 0.001). We found that wearing the BCL improved the optical quality of an eye in subject 1, expressed as the horizontal
MTF from 2 to 48 cycles per degree (cpd) for near vision and the Strehl ratio (t-test, P = 0.009 for Strehl ratio). But we did not find the same effect in subject 2. This difference may be due to the difference
in the aberrations of the eyes of the two subjects. 相似文献
40.
Stephane Klein Elise Kochanski Alain Strich Andrzej J. Sadlej 《Theoretical chemistry accounts》1996,94(2):75-91
Summary The dipole moments and dipole polarizabilities of the 1A1, 1B1, and 3B1 electronic states of the water molecule have been calculated by using the CASSCF approach followed by the evaluation of the dynamic electron correlation contribution by the second-order perturbation scheme CASPT2. All calculations have been carried out in a specifically extended ANO basis set which accounts for the Rydberg character of the two excited states. In order to estimate the correctness and accuracy of the present data a scan over a variety of different active spaces for the CASSCF wave function has been made. The present results are superior to earlier CASSCF calculations, although their qualitative features remain essentially the same. The dipole moments in 1B1 and 3B1 states are predicted to be about 0.49 a.u. and 0.33 a.u., respectively, and have the opposite orientation with respect to the ground state dipole moment. The dipole polarizability tensors of the excited states are characterized by high anisotropy and are dominated by the in-plane component perpendicular to the symmetry axis. All their components are found to be about an order of magnitude larger than those of the ground state polarizability tensor. The excitation energy dependence on the choice of the active orbital space in the CASSCF reference function is also considered and the analysis of the present data concludes in the concept of what is called the mutually compatible active spaces for the two states involved in excitation. All CASPT2 results are in good agreement with the results of recent calculations carried out in the framework of the open-shell coupled cluster formalism. This agreement confirms the high efficiency of the CASSCF/CASPT2 approach to the treatment of the electron correlation effects. 相似文献