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101.
102.
Sarah Sulzer‐Mossé Alexandre Alexakis Prof. Jiri Mareda Dr. Guillaume Bollot Gerald Bernardinelli Dr. Yaroslav Filinchuk Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(13):3204-3220
Chiral framework : Chiral amines with pyrrolidine frameworks catalyze the enantioselective conjugate addition of a wide range of aldehydes to various vinyl sulfones and vinyl phosphonates in high yields and with enantioselectivities up to >99 % ee (see scheme). The high versatility of the Michael adducts is exemplified by various functionalizations with conservation of the optical purity.
103.
Wang J Burdzinski G Kubicki J Platz MS Moss RA Fu X Piotrowiak P Myahkostupov M 《Journal of the American Chemical Society》2006,128(51):16446-16447
Ultrafast photolysis (lambdaex = 270, 350, or 360 nm) of bromophenyl, chlorophenyl, fluorophenyl, and fluoro-para-trifluoromethylphenyl diazirines produces transient species which absorb broadly in the UV and visible regions. Transient decay can be fit to either mono- or biexponential functions (tau1 approximately 0.3-10 ps, tau2 approximately 10-350 ps; dependent on solvent and halogen). Fluoro- and chlorophenylcarbene are formed within the time resolution of the spectrometer (300 fs, 270 nm excitation). Bromophenyl diazirine decay (270 nm excitation) correlates with the growth of bromophenylcarbene. Solvent and substituent effects on the slower decays of the transient absorptions are consistent with assigning the carriers of transient absorption in the visible region to ring-opened zwitterionic species. 相似文献
104.
Though molecular simulation of proteins has made notable contributions to the study of protein folding and kinetics, disagreement between simulation and experiment still exists. One of the criticisms levied against simulation is its failure to reproduce cooperative protein folding transitions. This weakness has been attributed to many factors such as a lack of polarizability and adequate capturing of solvent effects. This work, however, investigates how increasing the number of proteins simulated simultaneously can affect the cooperativity of folding transitions--a topic that has received little attention previously. Two proteins are studied in this work: phage T4 lysozyme (Protein Data Bank (PDB) ID: 7LZM) and phage 434 repressor (PDB ID: 1R69). The results show that increasing the number of proteins molecules simulated simultaneously leads to an increase in the macroscopic cooperativity for transitions that are inherently cooperative on the molecular level but has little effect on the cooperativity of other transitions. Taken as a whole, the results identify one area of consideration to improving simulations of protein folding. 相似文献
105.
Moss CL Liang W Li X Tureček F 《Journal of the American Society for Mass Spectrometry》2012,23(3):446-459
We report a new approach to investigating the mechanisms of fast peptide cation-radical dissociations based on an analysis
of time-resolved reaction progress by Ehrenfest dynamics, as applied to an Ala-Arg cation-radical model system. Calculations
of stationary points on the ground electronic state that were carried out with effective CCSD(T)/6-311++G(3df,2p) could not
explain the experimental branching ratios for loss of a hydrogen atom, ammonia, and N–Cα bond dissociation in (AR + 2H)+●. The Ehrenfest dynamics results indicate that the ground and low-lying excited electronic states of (AR + 2H)+● follow different reaction courses in the first 330 femtoseconds after electron attachment. The ground (X) state undergoes competing loss of N-terminal ammonia and isomerization to an aminoketyl radical intermediate that depend
on the vibrational energy of the charge-reduced ion. The A and B excited states involve electron capture in the Arg guanidine and carboxyl groups and are non-reactive on the short time scale.
The C state is dissociative and progresses to a fast loss of an H atom from the Arg guanidine group. Analogous results were obtained
by using the B3LYP and CAM-B3LYP density functionals for the excited state dynamics and including the universal M06-2X functional
for ground electronic state calculations. The results of this Ehrenfest dynamics study indicate that reaction pathway branching
into the various dissociation channels occurs in the early stages of electron attachment and is primarily determined by the
electronic states being accessed. This represents a new paradigm for the discussion of peptide dissociations in electron based
methods of mass spectrometry. 相似文献
106.
Rosaria Conte Bruce Edmonds Scott Moss R. Keith Sawyer 《Computational & Mathematical Organization Theory》2001,7(3):183-205
A lengthy and intensive debate about the role of sociology in agent based social simulation dominated the email list simsoc@jiscmail.ac.uk during the autumn of 2000. The debate turned on the importance of models being devised to capture the properties of whole social systems and whether those properties should determine agent behaviour or, conversely, whether the properties of social systems should emerge from the behaviour and interaction of the agents and, if so, how that emergence should be represented. The positions of four of the main protagonists concerned specifically with the modelling issues are reprised and extended in this symposium. 相似文献
107.
Development of high efficiency, multi-element CdZnTe detectors for portable measurement applications 总被引:3,自引:0,他引:3
T. H. Prettyman K. D. Ianakiev C. E. Moss S. A. Soldner M. R. Sweet M. C. Browne 《Journal of Radioanalytical and Nuclear Chemistry》2001,248(2):295-300
We describe the development of detector arrays and electronics for large-volume, hand-held CdZnTe detectors with the same counting efficiency as portable NaI(Tl) detectors presently used for nuclear material measurement applications. The pulse-height resolution of the multi-element detectors is at least three times better than NaI(Tl) over a wide energy range (from 100 keV to several MeV), enabling more accurate measurements of gamma-rays emitted by special nuclear material. Arrays of up to eight coplanar grid detectors can be combined to make detectors ranging in size from 4 to 14 cm3. Because the number of spectroscopy channels is small, low-power, hand-held detectors can be manufactured with conventional printed circuit board technology, thus keeping the cost of multi-element detectors to a minimum. The design and performance of an 8-element detector is presented. 相似文献
108.
Hexamethoxycyclopropane, obtained by reaction of lithiopentamethoxycyclopropane with dimethyl peroxide, decomposes at 200°C to dimethoxycarbene and tetramethoxyethylene. 相似文献
109.
J. P. Mossé P. Chevallier J. P. Briand 《Zeitschrift für Physik A Hadrons and Nuclei》1985,322(2):207-209
The natural width of a hypersatellite line (K ?2→K ?1 L ?1 transition) has been measured for the first time. In the case of Cu (Z=29) this width has been found equal toΓ = 5 eV, i.e. much larger than that of the diagram (K ?1→L ?1) line. This result follows a proposed empirical law assuming this width to be equal to 3Γ K+ΓL. 相似文献
110.
The reactions of the complexes [CpFe(CO)2]2[μ-(CH2)n with Ph3CPF6 yield cationic di-iron complexes of the type {[CpFe(C 相似文献