Vibrational-spectroscopy study of intermolecular dynamics of condensed matter IV. Temperature dependence of the low-frequency Raman scattering spectra of certain organic compounds

An experimental study was made of the Raman scattering spectra of more than 20 organic compounds in the polycrystalline state over a broad temperature range in the frequency range 20–150 cm^–1. General features are found in the temperature dependence of the line frequencies and widths: coalescence of lines into bands, spectral blurring, intensity redistribution, etc. At liquid-nitrogen temperature the number of low-frequency lines is consistent with the Born theory, while at high temperatures (how high depends on the particular substance) the orientational disorder of a crystal strongly affects the spectrum.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 2, pp. 75–83, February, 1971.     

Centralizing and normalizing constants for extrema and for records

A series of relations are given for the domains of attraction of limiting distributions and the corresponding centralizing and normalizing constants for extremal order statistics, record values, and some generalizations of record values.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 166, pp. 103–111, 1988.     

Cosmological constant in SUGRA models and the multiple-point principle

Physics of Atomic Nuclei - An attempt is made to explain the tiny order of magnitude of the cosmological constant in a model involvingt he following ingredients: supersymmetry breaking in N = 1...     

Gauge coupling unification in the exceptional supersymmetric Standard Model

We consider the renormalisation group flow of gauge couplings within the so-called exceptional supersymmetric Standard Model (E₆SSM) based on the low-energy matter content of 27-dimensional representations of the gauge group E₆$E_6$, together with two additional non-Higgs doublets. The two-loop beta functions are computed, and the threshold corrections are studied in the E₆SSM. Our results show that gauge coupling unification in the E₆SSM can be achieved for phenomenologically acceptable values of α₃(MZ)${\alpha }_3(M_Z)$, consistent with the central measured low-energy value, unlike in the minimal supersymmetric Standard Model (MSSM) which, ignoring the effects of high energy threshold corrections, requires significantly higher values of α₃(MZ)${\alpha }_3(M_Z)$, well above the experimentally measured central value.     

Repetitive cross-polarization contacts via equilibration-re-equilibration of the proton bath: Sensitivity enhancement for NMR of membrane proteins reconstituted in magnetically aligned bicelles

Thermodynamic limit of magnetization corresponding to the intact proton bath usually cannot be transferred in a single cross-polarization contact. This is mainly due to the finite ratio between the number densities of the high- and low-gamma nuclei, quantum-mechanical bounds on spin dynamics, and Hartmann-Hahn mismatches due to rf field inhomogeneity. Moreover, for fully hydrated membrane proteins refolded in magnetically oriented bicelles, short spin-lock relaxation times (T1ρ) and rf heating can further decrease cross polarization efficiency. Here we show that multiple equilibrations-re-equilibrations of the high- and low-spin reservoirs during the preparation period yield an over twofold gain in the magnetization transfer as compared to a single-contact cross polarization (CP), and up to 45% enhancement as compared to the mismatch-optimized CP-MOIST scheme for bicelle-reconstituted membrane proteins. This enhancement is achieved by employing the differences between the spin-lattice relaxation times for the high- and low-gamma spins. The new technique is applicable to systems with short T1ρ's, and speeds up acquisition of the multidimensional solid-state NMR spectra of oriented membrane proteins for their subsequent structural and dynamic studies.     

ChemInform Abstract: The Ground-State Potential Energy Surface of Diazene

has been studied by using a complete active space MCSCF wave function generated by distributing eight electrons among eight orbitals.