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81.
Valery G. Voinov Samuel E. Bennett Joseph S. Beckman Douglas F. Barofsky 《Journal of the American Society for Mass Spectrometry》2014,25(10):1730-1738
A radio frequency-free electromagnetostatic (EMS) cell devised for electron-capture dissociation (ECD) of ions has been retrofitted into the collision-induced dissociation (CID) section of a triple quadrupole mass spectrometer to enable recording of ECD product-ion mass spectra and simultaneous recording of ECD-CID product-ion mass spectra. This modified instrument can be used to produce easily interpretable ECD and ECD-CID product-ion mass spectra of tyrosine-phosphorylated peptides that cover over 50% of their respective amino-acid sequences and readily identify their respective sites of phosphorylation. ECD fragmentation of doubly protonated, tyrosine-phosphorylated peptides, which was difficult to observe with FT-ICR instruments, occurs efficiently in the EMS cell. Figure
? 相似文献
82.
The reaction of 1-ethoxycarbonylmethyl-5,5,7,7-tetramethyl-2-oxo-tetrahydroimidazo[1,5-b]oxadiazol-6-oxyl with the weakly basic nucleophiles NaN3, NaCN, KF, KBr, KCl and NaNO2 has been studied. It was shown for the first time that, as in the case of NaOH and MeONa, the reaction occurs with opening
of the oxadiazolone ring to form exo-N-substituted amidines. It was shown that the weakly basic nucleophiles readily react
with substrates which contain a substituent sensitive to attack by such nucleophiles as NaOH or MeONa. The effect of the nature
of the nucleophiles on the reaction course for opening of the oxadiazolone ring was also studied. It was found that the reactivity
of the nucleophiles in DMSO changes in the series F− > CN− > N3– >NO2− > Cl− > Br− and qualitatively correlates with their basicities in this solvent. Examination of the effect of the ratio of the reagents
on the degree of conversion of the starting oxadiazolone has shown that a quantity of nucleophiles less than one equivalent
also allowed the cleavage reaction of the oxadiazolone heterocycle to go to completion through just increasing the reaction
time. The experimental data obtained lends support to the proposed reaction scheme.
Dedicated to Academician B. A. Trofimov in his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 71–78, January, 2009. 相似文献
83.
Voinov MA Sosa Pagán JO Morrison E Smirnova TI Smirnov AI 《Journal of the American Chemical Society》2011,133(1):35-41
Emerging applications of nanosized iron oxides in nanotechnology introduce vast quantities of nanomaterials into the human environment, thus raising some concerns. Here we report that the surface of γ-Fe(2)O(3) nanoparticles 20-40 nm in diameter mediates production of highly reactive hydroxyl radicals (OH(?)) under conditions of the biologically relevant superoxide-driven Fenton reaction. By conducting comparative spin-trapping EPR experiments, we show that the free radical production is attributed primarily to the catalytic reactions at the nanoparticles' surface rather than being caused by the dissolved metal ions released by the nanoparticles as previously thought. Moreover, the catalytic centers on the nanoparticle surface were found to be at least 50-fold more effective in OH(?) radical production than the dissolved Fe(3+) ions. Conventional surface modification methods such as passivating the nanoparticles' surface with up to 935 molecules of oleate or up to 18 molecules of bovine serum albumin per iron oxide core were found to be rather ineffective in suppressing production of the hydroxyl radicals. The experimental protocols developed in this study could be used as one of the approaches for developing analytical assays for assessing the free radical generating activity of a variety of nanomaterials that is potentially related to their biotoxicity. 相似文献
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Nikolay V. Aksenov Patrick Steinegger Farid Sh. Abdullin Yury V. Albin Gospodin A. Bozhikov Viktor I. Chepigin Robert Eichler Vyacheslav Ya. Lebedev Alexander Sh. Madumarov Oleg N. Malyshev Oleg V. Petrushkin Alexander N. Polyakov Yury A. Popov Alexey V. Sabel’nikov Roman N. Sagaidak Igor V. Shirokovsky Maksim V. Shumeiko Gennadii Ya. Starodub Yury S. Tsyganov Vladimir K. Utyonkov Alexey A. Voinov Grigory K. Vostokin Alexander V. Yeremin Sergey N. Dmitriev 《The European Physical Journal A - Hadrons and Nuclei》2017,53(7):158
86.
Pyatyshev A. Yu. Skrabatun A. V. Rusak A. A. Sverbil P. P. Voinov Yu. P. 《Journal of Russian Laser Research》2021,42(6):645-649
Journal of Russian Laser Research - We record stimulated Raman scattering spectra in chemically-pure glycerol with the formation of two Stokes satellites with equidistant Raman frequencies ν =... 相似文献
87.
Tables of unbiased estimators with minimal variances for functions of the parameters of multinomial and negative multinomial
distributions are collected. Bibliography: 10 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 207, pp. 13–18, 1993.
Translated by V. Sudakov. 相似文献
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