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111.
Microcolumns with self-assembled particle frits for proteomics 总被引:1,自引:0,他引:1
LC-MS-MS experiments in proteomics are usually performed with packed microcolumns employing frits or outlets smaller than the particle diameter to retain the packing material. We have developed packed microcolumns using self-assembled particles (SAPs) as frits that are smaller than the size of the outlet. A five to one ratio of outlet size to particle diameter appears to be the upper maximum. In these situations the particles assembled into an arch over the outlet like the stones in a stone bridge. When 3 microm particles were packed into a tapered column with an 8 microm outlet, two particles bridged the outlet with 0.3 pl dead volume and perfect success rate. In peptide analysis by LC-MS, the peak width at half height was normally less than 6 s, compared to 12 s without SAPs. The LC-MS-MS system provided 37% sequence coverage (21 matched peptides) for a tryptically-digested sample of 10 fmol bovine serum albumin. We also describe application of the SAP principle to make disposable pipette tip columns with short pieces of fused-silica capillary as the outlet. 相似文献
112.
(?)-β-Caryophyllene (1) adopts three conformations in solution: αα(48%), βα(28%), and ββ(24%). The conformations were identified by an analysis of the 13C- and 1H-NMR spectra at ?87.2 and ?153.8° in connection with APT, HETCOR, and COSY spectra, and subsequent NOESY experiments. The activation parameters of the conversion αα → βα were determined from a bandshape analysis of exchange-broadened 13C-NMR spectra of 8-[methylene-13C]- 1 to give ΔH≠ = 5.9 ± 0.3 kcal/mol, ΔS? = ?8.1 ± 1.8 cal/mol. · K. and ΔG = ?8.3 ± 0.8 kcal/mol. The observed population ratio of the different conformers is best described by MM3. 相似文献
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Thep-state pairing idea proposed recently to explain the ferromagnetism of ZrZn2 is described in more detail, and the underlying soft-mode hypothesis is examined in relation with experiments, in particular the discovery of antiferromagnetism in TiBe2. The key result, namely an electron-phonon contribution to the Stoner factor given essentially by the mass enhancement factor, is used to explain the behaviour of the Curie pointT
m
and to predict an isotope effect.p-state superconductivity with a transition temperature determined by is predicted in TiBe2 and, above the critical pressure whereT
m
=0, also in ZrZn2.Work in La Jolla supported by NSF/DMR 77-08469. 相似文献
115.
Ida Vang Andersen Rocío García-Vzquez Umberto Maria Battisti Matthias M. Herth 《Molecules (Basel, Switzerland)》2022,27(13)
Radiolabeling of tetrazines has gained increasing attention due to their important role in pretargeted imaging or therapy. The most commonly used radionuclide in PET imaging is fluorine-18. For this reason, we have recently developed a method which enables the direct aromatic 18F-fluorination of tetrazines using stannane precursors through copper-mediated fluorinations. Herein, we further optimized this labeling procedure. 3-(3-fluorophenyl)-1,2,4,5-tetrazine was chosen for this purpose because of its high reactivity and respective limited stability during the labeling process. By optimizing parameters such as elution conditions, precursor amount, catalyst, time or temperature, the radiochemical yield (RCY) could be increased by approximately 30%. These conditions were then applied to optimize the RCY of a recently successfully developed and promising pretargeting imaging agent. This agent could be isolated in a decay corrected RCY of 14 ± 3% and Am of 201 ± 30 GBq/µmol in a synthesis time of 70 min. Consequently, the RCY increased by 27%. 相似文献
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Klaus Merz Stefan Martin Vassili Pintchouk Hans Pritzkow Matthias Driess 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract The reactions of primary silylphosphanes and -arsanes 1 with BuLi yield the three-dimensional M2ER-aggregates 2 (E = P, As). We observed that the double lithiation of 1 in the presence of Li2O results in the formation of the aggregates 3 and 4. 相似文献