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The singular set of any Lipschitzian minimizer of a general quasiconvex functional is uniformly porous and hence its Hausdorff
dimension is strictly smaller than the space dimension 相似文献
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We present an expanded LC-model for nanoscale split-ring resonators (SRR), including the influence of dielectric host materials. The LC-model is experimentally verified by changing the geometry of the SRR unit cell as well as by optofluidic tuning, where the SRR samples are covered with index oil. The extended model can be used as a general guideline for metal SRR structures with arbitrary dielectric host materials. 相似文献
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The unusual stability of a structured but locally flexible protein, human growth hormone (hGH) at pH 2.7, was investigated using the temperature dependence of the nanosecond-picosecond dynamics of the backbone amide groups obtained from (15)N NMR relaxation data. It is found that the flexibility of the backbone of the helices decreases with temperature in the range from 24 °C to ~40 °C, corresponding to an increasing stability. A concomitant increase with temperature of the electrostatic interactions between charged residues forming an interhelical network of salt bridges at the center of the four-helix core suggests that these interactions give rise to the decreasing flexibility and increasing stability of the protein. However, numerous hydrophobic interactions in the interior of the four-helix core may also contribute. Above ~40 °C, where the thermal energy overcomes the electrostatic and hydrophobic interactions, a substantial increase in the flexibility of the helix backbones results in a highly positive contribution from the local conformational heat capacity, C(p,?conf), of the helix backbones to the total heat capacity, C(p), of the protein. This reduces the change in heat capacity upon unfolding, ΔC(p), increases the change in the Gibbs free energy, ΔG(unfold), and stabilizes the protein at high temperatures. A similar decrease in flexibility is found near other salt bridges in hGH and in Calmodulin and may be of general importance for the thermostability of proteins and, in particular, of the salt bridge intensive thermophilic proteins. 相似文献
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A user of an LALR(k) parser generator system may have difficulties in understanding how a given LALR(k) conflict is generated. This is especially difficult if the conflict does not correspond to an LR(k) conflict.A practical method for giving informative diagnostics on LALR(k) conflicts is presented. The diagnostics distinguish between those LALR(k) conflicts that correspond to LR(k) conflicts and those that do not. As a side effect the user is thus informed whether or not his grammar is in fact LR(k) despite not being LALR(k).The method is based on an algorithm for testing LR(k)-ness using the LR(0) machine supplied with LALR(k) lookahead sets. This algorithm is presented and its correctness is proved. 相似文献
59.
Benedicte Rønne Kristensen Assoc. Prof. Christian Marcus Pedersen 《European journal of organic chemistry》2023,26(16):e202300213
A self-promoted glycosylation method for the stereoselective formation of β-glucosides from a substrate library of glycosyl trichloroacetimidate glycosyl donors and glycosyl acceptors is presented. The simple two-component reaction takes place at elevated temperatures, without the addition of any additives or catalysts. After a simple basic workup, N-glycosides were obtained in good yields and with high β-selectivity and hence this method allows for easy access to glycoconjugates under very mild conditions. The influences of neighboring group participation and substituents, in both the glycosyl donor and acceptor, were studied. Kinetic data were obtained from in situ IR and these were used for a Hammett study. A connection between the pKa of the acceptor and reaction rate was found and new mechanistic insight in self-promoted glycosylations gained. 相似文献
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Reisner W Beech JP Larsen NB Flyvbjerg H Kristensen A Tegenfeldt JO 《Physical review letters》2007,99(5):058302
We show that the ionic environment plays a critical role in determining the configurational properties of DNA confined in silica nanochannels. The extension of DNA in the nanochannels increases as the ionic strength is reduced, almost tripling over two decades in ionic strength for channels around 100 x 100 nm in dimension. Surprisingly, we find that the variation of the persistence length alone with ionic strength is not enough to explain our results. The effect is due mainly to increasing self-avoidance created by the reduced screening of electrostatic interactions at low ionic strength. To quantify the increase in self-avoidance, we introduce a new parameter into the de Gennes theory: an effective DNA width that gives the increase in the excluded volume due to electrostatic repulsion. 相似文献