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141.
142.
Kalenius E Beyeh NK Jänis J Rissanen K 《Chemical communications (Cambridge, England)》2011,47(9):2649-2651
Pyrogallarene shows concentration-dependent instability in dilute solutions resulting in elimination of two ketene molecules and formation of pyrogallarene lactones. This unexpected phenomenon, which is not observed with resorcinarenes, highlights the significance of the four hydroxyl groups at 2-position for the molecular characteristics of pyrogallarenes. 相似文献
143.
Microwave assisted acid cleavage was applied directly to intact adenovirus type 5 to achieve denaturation and proteolysis in a single reaction. The speed of the digestion, coupled with the simplicity of MALDI analysis, allowed peptide products to be profiled in less than 5 min. Identification of peptides from a range of proteins by MALDI-TOF confirms that both denaturation and proteolysis were achieved using low concentrations of acetic acid (12.5%) and short incubations (1.5 to 2 min) at high temperatures (140° C). These conditions favor production of peptides that carry Asp on their C-termini. When this cleavage reaction is carried out in highly enriched H(2) (18)O, a single atom of (18)O is introduced site-specifically into the carboxyl terminal. The labeling reaction is applied to label reporter peptides from human adenovirus type 5 harvested from HeLa cells. Small peptide products of endogenous processing were also observed. 相似文献
144.
145.
Janne Pesonen Krister O. E. Henriksson Jose Ramon López-Blanco Pablo Chacón 《Journal of mathematical chemistry》2012,50(6):1521-1549
Normal mode analysis (NMA) was introduced in 1930s as a framework to understand the structure of the observed vibration-rotation
spectrum of several small molecules. During the past three decades NMA has also become a popular alternative to figuring out
the large-scale motion of proteins and other macromolecules. However, the “standard” NMA is based on approximations, which
sometimes are unphysical. Especially problematic is the assumption that atoms move only “infinitesimally”, which, of course,
is an oxymoron when large amplitude motions are concerned. The “infinitesimal” approximation has the further unfortunate side
effect of masking the physical importance of the coupling between vibrational and rotational degrees of freedom. Here, we
present a novel formulation of the NMA, which is applied for finite motions in non-Eckart body-frame. Contrary to standard normal mode theory, our approach starts by assuming a harmonic potential in generalized coordinates,
and tries to avoid the linearization of the coordinates. It also takes explicitly into account the Coriolis terms, which couple vibrations and
rotations, and the terms involving Christoffel symbols, which are ignored by default in the standard NMA. We also computationally
explore the effect of various terms to the solutions of the NMA equation of motions. 相似文献
146.
Koshevoy IO Chang YC Karttunen AJ Selivanov SI Jänis J Haukka M Pakkanen T Tunik SP Chou PT 《Inorganic chemistry》2012,51(13):7392-7403
Treatment of Au(SC(4)H(8))Cl with a stoichiometric amount of hydroxyaliphatic alkyne in the presence of NEt(3) results in high-yield self-assembly of homoleptic clusters (AuC(2)R)(10) (R = 9-fluorenol (1), diphenylmethanol (2), 2,6-dimethyl-4-heptanol (3), 3-methyl-2-butanol (4), 4-methyl-2-pentanol (4), 1-cyclohexanol (6), 2-borneol (7)). The molecular compounds contain an unprecedented catenane metal core with two interlocked 5-membered rings. Reactions of the decanuclear clusters 1-7 with gold-diphosphine complex [Au(2)(1,4-PPh(2)-C(6)H(4)-PPh(2))(2)](2+) lead to octanuclear cationic derivatives [Au(8)(C(2)R)(6)(PPh(2)-C(6)H(4)-PPh(2))(2)](2+) (8-14), which consist of planar tetranuclear units {Au(4)(C(2)R)(4)} coupled with two fragments [AuPPh(2)-C(6)H(4)-PPh(2)(AuC(2)R)](+). The titled complexes were characterized by NMR and ESI-MS spectroscopy, and the structures of 1, 13, and 14 were determined by single-crystal X-ray diffraction analysis. The luminescence behavior of both Au(I)(10) and Au(I)(8) families has been studied, revealing efficient room-temperature phosphorescence in solution and in the solid state, with the maximum quantum yield approaching 100% (2 in solution). DFT computational studies showed that in both Au(I)(10) and Au(I)(8) clusters metal-centered Au → Au charge transfer transitions mixed with some π-alkynyl MLCT character play a dominant role in the observed phosphorescence. 相似文献
147.
148.
By subtracting from a recent lattice measurement of the thermal vector-current correlator the known 5-loop vacuum contribution,
we demonstrate that the remainder is small and shows no visible short-distance divergence. It can therefore in principle be
subjected to model-independent analytic continuation. Testing a particular implementation, we obtain estimates for the flavour-diffusion
coefficient (2πTD≳0.8) and electrical conductivity which are significantly smaller than previous results. Although systematic errors remain
beyond control at present, some aspects of our approach could be of a wider applicability. 相似文献
149.
Derek F. Laine 《Microchemical Journal》2009,91(1):125-268
A rapid electrochemical detection scheme for the improvised explosive, hexamethylene triperoxide diamine (HMTD) is demonstrated. This is based on the hydrolysis of HMTD releasing H2O2 and the electrochemical redox cycling of FeII/IIIEDTA via the following scheme:
FeIIIEDTA + e−→FeIIEDTA 相似文献
150.
Nadia Canilho Edis Kasëmi A. Dieter Schlüter Janne Ruokolainen Raffaele Mezzenga 《Macromolecular Symposia》2008,270(1):58-64
We describe how cationic dendronized polymers of generations 1, and 2 and anionic monoalkyl tails can be combined by supramolecular ionic complexation into comb-like liquid crystalline polymers. The final structures in bulk of these supramolecular complexes were studied by differential scanning calorimetry (DSC), cross-polarized optical microscopy (CPOM), small angle x-rays scattering (SAXS) and transmission electron microscopy (TEM). The combination of these techniques allowed elucidating (i) that these complexes exhibit thermotropic behaviour, (ii) that various liquid crystalline structures in the 3–5 nm length scale can be obtained such as columnar rectangular, columnar tetragonal, columnar hexagonal and lamellar, depending both on alkyl tail length and polymer generation, (iii) that although the alkyl tails represent the majority phase in the columnar phases, they form the cylindric domains, and the dendronized polymers occupy the continuous domains. Therefore, upon selective cleavage of the alkyl tails in the columnar phases, the present self-assembly approach may constitute an efficient strategy towards the formation of porous organic matrices with ultra-dense pore size in the range of 2 to 4 nm. 相似文献