Asymmetry, inherent

The delayed intensity decays essentially exponentially in time, which implies that there is no additional electric field gradient beyond the electric field gradient from the asymmetry inherent in the surface, that is, the surface is practically perfect and undisturbed. By stepwise increase in the temperature a beat appears at about 45 ns that become more pronounced with the temperature. The highest temperature of the experiment was 870 K in order to avoid destruction of the Fe monolayer by diffusion of Fe into the W substrate. When the temperature is lowered again to 300 K, the beat structure disappears and the original spectrum is recovered, proving that thermally activated defects are responsible for the beat... 

Systematic and well-pronounced deviation from verticality of the migration tracks both with 5-(- -)-ibuprofen and 5-(+)-naproxen certainly needs some sort of explanation, even if it is not possible for the time being to furnish an exhaustive molecular-level insight. It seems rather obvious that one reason is structural asymmetry of the employed analytes. The second reason must be certain kind of asymmetry inherent of the chromatographic system involved. With the nonchiral components of the employed mobile phases, it can only be the case with the stationary phase. 

Optical second harmonic generation (SHG), which is the conversion of two photons of frequency u to a single photon of frequency 2co, is known to be an inherently surface-sensitive technique, because it requires a noncentrosymmetrical medium. At the interface between two centrosymmetrical media, such as the interface between two liquids, only the molecules which participate in the asymmetry of the interface will contribute to the SHG [18]. SHG has been used as an in-situ probe of chemisorption, molecular orientation, and... 

Nigg EA, Stearns T (2011) The centrosome cycle centriole biogenesis, duplication and inherent asymmetries. Nat Cell Biol 13 1154-1160... 

Modem synthetic chemistry is increasingly focused on the formation, control, and induction of asymmetry in molecular stmcture. As the complexity of synthetic targets increases, in particular those derived from natural sources, the demands of the chemist for new and efficient methods for the introduction of new stereogenic centers has generated many elegant solutions. Since azomethine ylides are inherently achiral, the induction of stereocontrol has to be performed by attachment of a suitable stereodirecting unit onto either the dipole, or more recently onto the ylide, and latterly many elegant solutions have been developed. 

We have also learned that the point-successive methods need not demand more computer memory than point-simultaneous methods, and that the seemingly inherent asymmetry of the point-successive methods can be overcome. Furthermore, the linear methods described in this section are... 

The dimer (OEP)Sc—O—Sc(OEP) has been examined by optically detected magnetic resonance with the conclusion that the rings are approximately coplanar.27 The NMR spectra of the dimer and the monomer show that the methylene protons are anisochronous, this probably not being caused by hindered rotation but by the inherent asymmetry of the ligands.28... 

Attempts to induce asymmetry in the cyclisation of 57 using the chiral lithium amides, which had worked well with simple benzamides, were frustrated by the inherent chirality, at low temperature, of the naphthamide itself. This feature is common to all 2-substituted tertiary aromatic amides, which may become atropisomeric at low temperature due to slow rotation about the Ar-CO bond.48 We therefore sought to... 

The imperfection also may be interpreted as resulting from an inherent cellular asymmetry such as the entry point of the sperm or internal compartmentalization ((-------)... 

In order to resolve the issue of whether the observed pattern is due to an inherent asymmetry or a Turing type selforganization mechanism, one must make a calculation to see if the former can, in fact, explain the amplitude and ratios of ionic currents and other details of the pattern. 

Ortoleva, P. "inherent Asymmetry and Imperfect Bifurcation in the Developmental Scenario" (in preparation). 

The representative examples of chirogenic assemblies on the basis of achiral monomeric porphyrinoids exposed to a chiral influence clearly show their great importance and wide applicability in various fields. The major chiroptical properties of these relatively simple supramolecular systems include transferring the chiral information and controlling the induced asymmetry by different factors. However, another type of chirogenic process— modulation of inherent chirality is going to be illustrated for chiral porphyrins in the next sections. 

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