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71.
Sophie Nocquet‐Thibault Anita Rayar Dr. Pascal Retailleau Dr. Kevin Cariou Dr. Robert H. Dodd 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):14205-14210
In this study we demonstrate that the combination of bis(tert‐butylcarbonyloxy)iodobenzene and lithium azide in acetonitrile allows the diazidation of various enamide substrates. The azido‐oxyamination of the same substrates can be carried out in the presence of 2,2,6,6‐tetramethylpiperidine N‐oxide (TEMPO). Control experiments strongly suggest that this latter process occurs through a shift in nature of the in situ generated electrophilic species from a radical to a cation. Finally, the versatility of the novel compounds synthesized was also assessed by running various selective reactions on them. 相似文献
72.
Ga(III)protoporphyrin-IX (Ga-PP) has been proposed as a model for the key interporphyrin interactions in malaria pigment. Unlike the paramagnetic parent iron heme derivatives, Ga-PP is readily soluble in methanol (MeOH). We report optical, mass spectroscopic, and theoretical results for Ga-PP as well as its reactions with myoglobin. UV-visible absorption and MCD spectroscopy show that Ga-PP exhibits a typical spectrum for a main group metal: a Q-band at 539 nm and a B band at 406 nm when dissolved in MeOH. We also report optical data for Zn(II)protoporphyrin IX (Zn-PP) dissolved in MeOH, which exhibits a Q-band at 545 nm and a B band at 415 nm. ESI mass spectral data for Ga-PP dissolved in MeOH show the presence of predominantly monomers, with smaller fractions of dimers [(Ga-PP)(2)] and trimers. UV-visible and MCD absorption spectroscopy and ESI mass spectral data demonstrate the successful insertion of monomeric Ga-PP into apo-Mb. Ga-PP-Mb exhibits a B band at 417 nm and Q bands at 545 and 584 nm, which are all red-shifted from the free Ga-PP values. The calculated electronic structures and frontier molecular orbitals of Ga-PP, (Ga-PP)(2) and Zn-PP fit the previously reported trends in band energies and oscillator strengths as a function of molecular orbital energies. These new data can be applied to explain the experimentally observed optical spectroscopy. The observed Q-band energies are accounted for by calculated (HOMO-LUMO) gap of the frontier MOs, while the split in the two top occupied MOs accounts for the magnitude of the Q-band oscillator strength as well as the experimentally observed Q to B band energy separation. Although Ga-PP shares more spectroscopic properties with Zn-PP than it does with Fe(III)PPIX, the trivalent oxidation state allows this molecule to be used as a model for ferric hemes in heme proteins. 相似文献
73.
SJ Rose 《Contemporary Physics》2013,54(2):109-121
In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required. 相似文献
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Aaron Dodd 《Journal of nanoparticle research》2009,11(8):2171-2177
A three stage process consisting of mechanical milling, heat treatment, and washing has been investigated as a means of manufacturing
nanoparticulate powders of In2O3. In the first stage of processing, mechanical milling was used to prepare a nanocrystalline mixture of In2(SO4)3, Na2CO3, and NaCl. Subsequent heat treatment of the milled reactant resulted in the formation of nanocrystalline In2O3 particles embedded within a matrix of Na2SO4 and NaCl. In the final stage of processing, the In2O3 powder was recovered by washing with deionised water. The duration of milling was found to determine the degree of hard agglomeration
in the final washed powder. It was also found that the average particle size of the powder could be controlled between 8 and
18 nm by simply varying the temperature of the post-milling heat treatment over the range of 400 to 550°C. These results demonstrate
that solid state chemical reaction can be used as a technically simple method for manufacturing nanoparticulate In2O3 powders with a controlled particle size and low levels of hard agglomeration. 相似文献
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K. Kaimi H. Bøggild J. Boissevain M. Cherney J. Dodd S. Esumi C.W. Fabjan D.E. Fields A. Franz B. Holzer T.J. Humanic B. Jacak R. Jayanti H. Kalechofsky T. Kobayashi Y.Y. Lee M. Leltchouk B. Lörstad N. Maeda A. Medvedev A. Miyabayashi M. Murray S. Nishimura E. Noteboom S.U. Pandey F. Piuz V. Polychronakos M. Potekhin G. Poulard A. Sakaguchi J. Schmidt-Sorensen J. Simon-Gillo W. Sondheim T. Sugitate J.P. Sullivan Y. Sumi H. van Hecke W.J. Willis K. Wolf N. Xu 《Zeitschrift fur Physik C Particles and Fields》1997,75(4):619-625
The emission of pions from relativistic heavy-ion collisions of S+S, S+Ag and S+Pb at 200 GeV/nucleon is characterized using two-particle interferometry. The multiplicity dependence of the pion source parameters near midrapidity is studied. The transversal (R t) and longitudinal (R l) pion source parameters are independent of the initial nuclei in the interaction and increase with increasing multiplicity. This suggests that the freeze-out process is governed mainly by the particle multiplicity. The multiplicity dependence is weaker than that expected from a simple model of a freeze-out at a constant density. 相似文献
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