1,721,635 research outputs found
Comment on "self-assembled multiporphyrin arrays mediated by self-complementary quadrupole hydrogen bond motifs"
No full textThe self-assembly of discrete linear tapes claimed by the title communication is questioned on the basis of a rigorous thermodynamic analysis; moreover the reported thermodynamic data are not consistent with self-assembly of the square
Comment on 'using a convenient, quantitative model for torsional entropy to establish qualitative trends for molecular processes that restrict conformational freedom'
No full textNumerical Evaluation of Energy Levels and Wave Functions for Hindered Internal Rotation
No full textA numerical procedure for the solution of the one-dimensional Schrödinger equation (the finite-difference boundary-value method), especially suited for problems having periodic nature, is presented and applied to the problem of hindered internal rotation. The accuracy of the numerical method, as a function of the number of mesh points, is evaluated by comparing the approximate numerical results with the exact ones, relative to the case of free internal rotation. The hindered rotation in ethane is then examined in detail, and the character of the obtained energy levels is discussed by a comparison with the energy levels of the two limiting cases of torsional vibration and shifted potential free rotation. An approximate procedure for the treatment of internal rotations involving asymmetric tops is also suggested, and applied to the case of 1,2-dichloroethane. The results show a satisfactory agreement with those obtained by the more elaborate method of Chung-Phillips and with the experimental one
Predictive indices of morbidity and mortality after liver resection [9]
No full textMELD score is an usuful method to predict post-operative liver failure in cirrhotic patient
Erratum: Predictive indices of morbidity and mortality after liver resection (Annals of Surgery (2006) 244, (635-637))
No full textcomment to Editoria
The origin of cooperativity in double-wheel receptors. Freezing of internal rotation or ligand-induced torsional strain?
No full text
Determination of the rotational barrier in ethane by vibrational spectroscopy and statistical thermodynamics
No full textA model for self-assembly in solution
No full textA model treating the competition, under thermodynamic control, between self-assembly and nonlinear random polymerization is presented. The fundamental quantities on which the treatment is based are the effective molarity (EM) of the assembly and the equilibrium constant for the intermolecular model reaction between monofunctional reactants (Kinter). Knowledge of these quantities allows the evaluation of the distribution curve of the self-assembling complex. In order for effective self-assembly to take place, the product KinterEM must be no lower than a limit value easily computable on the basis of simple structural parameters such as the number of molecules in the assembly (N), the number of bonds joining them (B), and the number of interaction sites in the monomers. This limit decreases on decreasing N and on increasing B, and the most obvious way to realize this condition is by increasing the degree of cyclicity of the assembly (B − N + 1). The yield of an assembly with a high degree of cyclicity is very sensitive also to modest changes of KinterEM about its limit value. Depending on the value of the monomers concentration, the assembly could undergo either sharp disassembly (denaturation) or conversion into gel
Principles for Designing an Achiral Receptor Promoting Asymmetric Autocatalysis with Amplification of Chirality
No full textThe idea that an achiral receptor can promote asymmetric autocatalysis with amplification of chirality is presented and discussed in the light of two models, dubbed ACM1 and ACM2, corresponding to the autocatalytic versions of the classical Kagan and Noyori models for non-linear effects in asymmetric catalysis. The chiral amplifications produced by the two models have been investigated. The results suggest that an achiral receptor working according to the ACM1 model presents distinct advantages over the ACM2 counterpart, both in terms of elegance of design and performance
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