谈谈量子力学中的状态叠加原理

以对话的形式,介绍并评论了布洛欣采夫、狄拉克以及朗道和栗弗席茨关于状态叠加原理的不同表述.     

The Maximum Hardness Principle and the Composition of Zn(II) and Cd(II) Tetrafluoroborate Complexes with Nitrogen-Containing Organic Bases

The hardness/softness parameters of the central complexing ion, the donor nitrogen atom of the ligand, and the coordination bond were calculated for zinc and cadmium tetrafluoroborate complexes with nitrogen-containing organic bases of various composition (both experimentally determined and hypothetical). On the basis of the quantitative estimate of the hard/soft characteristics of the whole series of the coordination compounds considered, it was found that the hardest parameters are inherent in the complexes isolated in a pure state by a preparative method.     

De novo sequencing of peptides secreted by the skin glands of the Caucasian Green Frog Rana ridibunda

Amphibian skin glands are known to secrete various types of bioactive peptides. The array of these peptides is specific for every frog species. The present research deals with the identification of peptides isolated from the skin secretion of the Marsh frog R. ridibunda inhabiting the Kolkhida Canyon of the Caucasian region. The research is based on comprehensive high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) analysis of intact and chemically modified peptides. In particular, an oxidation procedure was applied directly to the crude skin secretion to open S--S loops whereas N-terminal acetylation was additionally carried out for one individual peptide. Sequences were determined by manual interpretation of electron capture dissociation (ECD) and collisionally induced dissociation (CID) tandem mass spectra. A total of 29 peptides were identified in the skin secretion of the Caucasian Marsh frog. The peptide profile is represented with disulfide-containing peptides belonging to the brevinin, esculentin and ranatuerin families, neuropeptides of the bradykinin and bombesin families. Two identified peptides belonging to the ranatuerins are the first peptides of this family discovered in the skin secretions of European frogs. Ten of the identified peptides coincide with those reported earlier for the European Edible frog. Another ten are identical to those found in R. ridubunda from the Moscow region. This fact verifies the described method as being an efficient analytical tool to compare intra- and interspecific variabilities.     

Long-range order in quasi-one-dimensional conductors

We study the formation of the charge-density wave long-range order in a system of repulsive 1D electrons coupled to 3D phonons. We show that the charge-density wave can be stabilized by interaction with phonons in quasi-1D crystals and semiconducting nanowires. In the case of metallic atomic chains, interaction with phonons of a 3D substrate is not enough, and violation of the translational invariance by commensurable perturbation or disorder is needed. The possibility of stabilization of superconductivity in 1D electrons with attraction by means of tunnel coupling to a 3D metal is considered.     

Magnetic field tuning of polaron losses in Fe doped BaTiO(3) single crystals

Artificial tuning of dielectric parameters can result from interface conductivity in polycrystalline materials. In ferroelectric single crystals, it has already been shown that ferroelectric domain walls can be the source of such artificial coupling. We show here that low-temperature dielectric losses can be tuned by a dc magnetic field. Since such losses were previously ascribed to polaron relaxation we suggest this results from the interaction of hopping polarons with the magnetic field. The fact that this loss alteration has no counterpart in the real part of the dielectric permittivity confirms that no interface is involved in this purely dynamical effect. The contribution of mobile charges hopping among Fe-related centers was confirmed by ESR spectroscopy, showing a maximum intensity at ca T?～?40?K.     

Solitons with a localized electronic state in quasi-one-dimensional conductors with a charge-density wave

It is shown that self-trapped soliton states, in which the position of the electronic level in the Peierls gap 2Δ is shifted from the center of the gap by an amount of the order of Δ, can exist in quasi-one-dimensional conductors possessing a charge-density wave. The energy of the level is determined by the local position of the chemical potential and depends on the parameters of the crystal and the temperature. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 1, 49–54 (10 January 1996)