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991.
992.
993.
We obtain a complete derived equivalence classification of the cluster-tilted algebras of Dynkin type E. There are 67, 416, 1574 algebras in types E 6, E 7 and E 8 which turn out to fall into 6, 14, 15 derived equivalence classes, respectively. This classification can be achieved computationally and we outline an algorithm which has been implemented to carry out this task. We also make the classification explicit by giving standard forms for each derived equivalence class as well as complete lists of the algebras contained in each class; as these lists are quite long they are provided as supplementary material to this paper. From a structural point of view the remarkable outcome of our classification is that two cluster-tilted algebras of Dynkin type E are derived equivalent if and only if their Cartan matrices represent equivalent bilinear forms over the integers which in turn happens if and only if the two algebras are connected by a sequence of “good” mutations. This is reminiscent of the derived equivalence classification of cluster-tilted algebras of Dynkin type A, but quite different from the situation in Dynkin type D where a far-reaching classification has been obtained using similar methods as in the present paper but some very subtle questions are still open. 相似文献
994.
Thorsten W. Jaskolla Michael Karas Udo Roth Kerstin Steinert Christoph Menzel Karsten Reihs 《Journal of the American Society for Mass Spectrometry》2009,20(6):1104-1114
The properties of several cinnamic acid compounds used as matrices for matrix-assisted laser desorption ionization time-of-flight
mass spectrometry (MALDI-TOF MS) were investigated as standard dried droplet (DD) and vacuum sublimed preparations. The differences
between both preparation methods were analyzed with regard to matrix grain size, internal ion energy, initial velocity, analyte
intensity, and analyte incorporation depth. Some of the used cinnamic acid derivatives exhibit clearly reduced grain sizes
as sublimed preparations compared with standard DD approaches. In these cases higher effective temperatures could be measured
accompanied by increased analyte intensities, which can be explained by stronger volatilization processes caused by a hindered
heat dissipation resulting in a raised analyte transfer into the gas phase. For all sublimed compounds, a strong increase
of the initial ion velocity compared with DD preparations could be measured. Higher initial ion velocities correlate with
a decrease in internal ion energy which might be attributed to the very uniform crystal morphology exhibited by sublimed compounds.
For sublimed matrices without reduced grain size, at least slightly higher analyte intensities could be detected at raised
laser fluences. Analyte accumulation in the uppermost matrix layers or the detected higher ion stability can be explanations
for these results. 相似文献
995.
Philipp Selig Dr. Eberhardt Herdtweck Dr. Thorsten Bach Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(14):3509-3525
The stereogenic centers at C3 and C12 of meloscine ( 3 ) can be established in the photochemical key step 1 → 2 . 1,2‐retro‐Benzilic acid rearrangement to a five‐membered ring, reductive amination, Claisen rearrangement, and ring‐closing metathesis are further key steps in the transformation of cyclobutane 2 into the target molecule 3 (14 steps, 9 % overall yield). Enantioselective access to (+)‐meloscine was possible when the [2+2]‐photocycloaddition was conducted in the presence of a chiral template.
996.
The reactions of the mass-selected gas-phase gold cluster cations Au3+ and Au5+ with H2O, CH3Cl, and mixtures of these reactants were studied under well-defined multi-collision conditions in an octopole ion trap. The reaction of CH3Cl with the gold cations was found to proceed fast at room temperature, leading to the adsorption of one CH3Cl molecule at each ‘corner’ atom of the cluster ion. This strong adsorption hindered the coadsorption of other reactants like H2O. However, a considerable reduction of the CH3Cl partial pressure led to distinct patterns of H2O/CH3Cl coadsorption products. Furthermore, the mass spectra indicated the loss of hydrogen after the reaction of CH3Cl with Au3+. 相似文献
997.
Yoh Matsuki Dr. Thorsten Maly Dr. Olivier Ouari Dr. Hakim Karoui Dr. François Le Moigne Dr. Egon Rizzato Dr. Sevdalina Lyubenova Dr. Judith Herzfeld Prof. Thomas Prisner Prof. Paul Tordo Prof. Robert G. Griffin Prof. 《Angewandte Chemie (International ed. in English)》2009,48(27):4996-5000
A new polarizing agent with superior performance in dynamic nuclear polarization experiments is introduced, and utilizes two TEMPO (2,2,6,6‐tetramethylpiperidine‐1‐oxyl) moieties connected through a rigid spiro tether (see structure). The observed NMR signal intensities were enhanced by a factor of 1.4 compared to those of TOTAPOL, a previously described TEMPO‐based biradical with a flexible tether.
998.
Smit T Türckheim F Mores R 《The Journal of the Acoustical Society of America》2010,127(5):EL222-EL226
This paper introduces a fully automated plucking apparatus for stringed instruments. The basic idea of the proposed mechanism is to make use of the constant tensile strength of bare wires. It defines the plucking intensity of a clasped string by pulling the wire until it breaks. The main components of the apparatus are bare wires for the string plucking, solenoids for the transmission of traction, bipolar transistors for the electric circuit switching, and a signal generator for the trigger settings. The mean average of the correlation coefficients between several individual excitations is well above 99%. 相似文献
999.
Marquardsen T Hofmann M Hollander JG Loch CM Kiihne SR Engelke F Siegal G 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2006,182(1):55-65
NMR based ligand screening is becoming increasingly important for the very early stages of drug discovery. We have proposed a method that makes highly efficient use of a single sample of a scarce target, or one with poor or limited solubility, to screen an entire compound library. This comparative method is based on immobilizing the target for the screening procedure. In order to support the method, a dual cell, flow injection probe with a single receiver coil has been constructed. The flow injection probe has been mated to a single high performance pump and sample handling system to enable the automated analysis of large numbers of compound mixes for binding to the target. The probe, having an 8 mm 1H/2H dual tuned coil and triple axis gradients, is easily shimmed and yields NMR spectra of comparable quality to a standard 5 mm high-resolution probe. The lineshape in the presence of a solid support is identical to that in glass NMR tubes in a 5 mm probe. Control spectra of each cell are identical and well separated, while ligand binding in a complex mixture can be readily detected in 20-30 min, thus paving the way for use of the probe for actual drug discovery efforts. 相似文献
1000.
Gelation of the reaction mixture and insolubility of the poly(p‐phenylene vinylenes) (PPVs) when isolated at this stage, but complete redissolution of the gel and excellent solubility of the resulting PPVs after further stirring for hours or days, is a phenomenon in Gilch polymerizations that has not been explained so far. It is verified that, in agreement with the literature, specific additives prevent gelation. However, it is also shown that chemical crosslinking is certainly not the reason for gel formation. Instead, it seems to be the consequence of a very high entanglement density in the pristine PPVs, which requires time for relaxation. The mentioned additives seem to support this dis‐entanglement process.