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41.
Jos Carlos Antunes Marques Arnold Falick Andras Heusler Daniel Stahl Pierre Tecon Tino Gumann 《Helvetica chimica acta》1984,67(2):425-433
Loss of CH, CH4, C2H4, C3H, C3H6 and C3H7 from the molecular ions of a number of 13C-labeled analogs of 4,4-dimethyl-1-pentene was studied both in normal (source) 70-eV electron impact (EI) spectra dn in metastable spectra. For loss of CH in the source, 96% of the methyl comes frm positions of 5, 5′ and 5″, while the remainder comes from position 1. In the metastable spectra, loss of C-1 (16%) and C-3 (9%) is increasing in importance. The loss of ethylene is a particular case: either C-1 or C-3 are lost with any other C-atom from positions 2,5,5′, and 5″ (8 × 10%) in the metastable spectra, the probability for simultaneous loss of C-1 and C-3 being 6%. If C-1 seems to these two positions become completely equivalent in the metastable time range. The T-values (kinetic energy release) for the different positions show small, but statisticaly different values and a small isotope effect. Loss of C3H5 (allylic cleavage) is 100% C-1, C-2 and C-3, i.e., no evidence for skeletal rearrangement is seen. This is also true for loss of C3C6 (McLafferty rearrangement) within the source, but in metastable decay the other positions gain in importance. The neutral fragment C3H appears to be the the result of consecutive loss of CH and C3H4, rather than a one-step loss of propyl radical or the inverse reactions sequence. No metastable reaction can be seen for this reaction. Decomposition of labeled C6H and C5H secondary ions occurs in an essentially random fashion. 相似文献
42.
T. Birendra Singh Xiwen Chen Wallace W. H. Wong Tino Ehlig Peter Kemppinen Ming Chen Scott E. Watkins Kevin N. Winzenberg Steven Holdcroft David J. Jones Andrew B. Holmes 《Applied Physics A: Materials Science & Processing》2012,108(3):515-520
Charge extraction properties of various binary and ternary blends of organic photovoltaic devices covering both polymers and small molecules are studied. Due to their bipolar nature, both slow and fast carrier mobilities are identified from the extraction current transient. The equilibrium carrier concentration is also estimated for each of the blend films. The product of the slow carrier mobility and equilibrium concentration spreading two orders of magnitude can be used to estimate the short circuit current density. A good agreement between the estimated and measured short circuit current density is obtained with the accuracy reliant on the estimation of the slowest carrier mobility. This simplistic approach will be very useful to predict the short circuit current density for devices based on new materials. 相似文献
43.
Just T Gafumbegete E Gramberg J Prüfer I Mikkat S Ringel B Pau HW Glocker MO 《Analytical and bioanalytical chemistry》2006,384(5):1134-1144
A proteomic approach has been used to establish a proteome map and differentiate between the protein composition of tonsils
from patients with chronic tonsillitis (CT) and that of tonsils with hyperplasia (HPL). Two-dimensional gel analysis was performed
with material from four patients with HPL and five patients with CT. An average of approximately 600 spots were detected in
each gel. A total of 127 different proteins were identified in 158 spots analyzed by mass spectrometry. Our study revealed
disease-associated differences between protein abundance for two protein spots, an HSP27 isoform and UMP-CMP kinase. Both
protein spots were more abundant in the CT group. HSP27 ELISA was performed for 32 patients, 12 belonging to the HPL group
and 20 to the CT group. ELISA could not be used to differentiate HSP27 isoforms nor to distinguish CT from HPL. HSP27 was
found to migrate to two further protein spots in the 2D gels. The differently expressed HSP27 isoform migrated as the most
acidic of all the HSP27 isoforms detected, indicating the highest degree of phosphorylation. The sum of all three HSP27 abundances
in the gels from the CT group was not different from that of the HPL group, consistent with the ELISA results. Our results
suggest that phosphorylation differences caused the observed migration differences of HSP27. Together with the UMP-CMP kinase
abundance differences, we conclude that kinase and/or phosphatase activity are different in CT and HPL.
This paper was presented at the 38th Annual Meeting of the German Society for Mass Spectrometry (DGMS) held in March 2005
in Rostock, Germany. 相似文献
44.
Stefano Provera Giuseppe Guercio Lucilla Turco Ornella Curcuruto Giuseppe Alvaro Tino Rossi Carla Marchioro 《Magnetic resonance in chemistry : MRC》2010,48(7):523-530
Liquid chromatography‐NMR (LC–NMR) spectroscopy was used to obtain detailed information regarding the structure of the major bulk drug impurities present in GW597599 (vestipitant). The one‐dimensional 1H LC–NMR experiments were performed in both continuous and stop‐flow modes on a sample of GW597599 (vestipitant) enriched with mother liquor impurities. The information derived from both LC–NMR and LC–MS data provided the structural information of all major impurities. The full characterisation of the impurities by high‐resolution NMR spectroscopy was ultimately performed on appropriately synthesised compounds. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
45.
Josef Seibl und Tino Gäumann 《Fresenius' Journal of Analytical Chemistry》1963,197(1):33-42
Zusammenfassung Die Massenspektren einer Reihe monocyclischer Ketone werden untersucht und durch Vergleich mit den Spektren der entsprechenden mit Deuterium bzw. 18O markierten Verbindungen die Art ihrer Fragmentierung unter Elektronenbeschuß verfolgt. Mechanismen für die wichtigsten Zerfallsreaktionen werden vorgeschlagen, die mit den experimentellen Befunden in Einklang stehen.
Den Herren Prof. H. H. Günthard und V. Prelog danken wir für die wohlwollende Förderung dieser Arbeit. Sie wurde von der Schweizerischen Kommission für Atomwissenschaft (Projekt A151) und dem Schweizerischen Nationalfonds (Projekt 2011) unterstützt, wofür wir auch hier bestens danken möchten. 相似文献
Summary The mass spectra of a series of monocyclic ketones are investigated and the modes of fragmentation under electron impact studied by comparison with the spectra of deuterated and 18O-labelled compounds. Reaction mechanisms are proposed for the formation of the most important fragments, which are in agreement with the experimental results.
Den Herren Prof. H. H. Günthard und V. Prelog danken wir für die wohlwollende Förderung dieser Arbeit. Sie wurde von der Schweizerischen Kommission für Atomwissenschaft (Projekt A151) und dem Schweizerischen Nationalfonds (Projekt 2011) unterstützt, wofür wir auch hier bestens danken möchten. 相似文献
46.
Effects of dose and temperature on the yields of the majority of the radiolysis products of the n-heptane, n-octane, n-nonane, n-decane and n-dodecane have been determined. The G-values of the products, excepting dimers are approximately the same for all the above n-alcanes. The temperature dependence, expressed as an apparent activation energy is shown to be equal for all n-alcanes. 相似文献
47.
The electron impact fragmentation of n-heptane has been investigated using 13C labelled derivatives. A mechanism is proposed for the loss of alkyl radicals where the cleavage of a C? C bond is coupled with the rearrangement of a hydrogen atom, thus yielding a secondary alkyl ion that eventually fragments further by a subsequent loss of olefin. For alkyl ions with less than six carbon atoms this consecutive pathway is in competition with formation directly from the molecular ion. The consecutive pathway contributes about 15% to the intensity of the alkyl ions with four and five carbon atoms and 80% for smaller ions. The electron energy dependence was studied. 相似文献
48.
Tino Reppe Dr. Silvio Poppe Prof. Dr. Carsten Tschierske 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):16066-16079
Spontaneous development of chirality in systems composed of achiral molecules is important for new routes to asymmetric synthesis, chiral superstructures and materials, as well as for the understanding of the mechanisms of emergence of prebiotic chirality. Herein, it is shown that the 4,4′-diphenylbenzil unit is a universal transiently chiral bent building block for the design of multi-chained (polycatenar) rod-like molecules capable of forming a wide variety of helically twisted network structures in the liquid, the liquid crystalline (LC) and the crystalline state. Single polar substituents at the apex of tricatenar molecules support the formation of the achiral (racemic) cubic double network phase with Ia d symmetry and relatively small twist along the networks. The combination of an alkyl chain with fluorine substitution leads to the homogeneously chiral triple network phase with I23 space group, and in addition, provides a mirror symmetry broken liquid. Replacing F by Cl or Br further increases the twist, leading to a short pitch double gyroid Ia d phase, which is achiral again. The effects of the structural variations on the network structures, either leading to achiral phases or chiral conglomerates are analyzed. 相似文献
49.
50.
Ferrari G Cancio P Drullinger R Giusfredi G Poli N Prevedelli M Toninelli C Tino GM 《Physical review letters》2003,91(24):243002
We report the direct frequency measurement of the visible 5s(2) 1S0-5s5p 3P1 intercombination line of strontium that is considered a possible candidate for a future optical-frequency standard. The frequency of a cavity-stabilized laser is locked to the saturated fluorescence in a thermal Sr atomic beam and is measured with an optical-frequency comb generator referenced to the SI second through a global positioning system signal. The 88Sr transition is measured to be at 434 829 121 311 (10) kHz. We measure also the 88Sr-86Sr isotope shift to be 163 817.4 (0.2) kHz. 相似文献