Neutron Scattering Techniques and Complementary Methods for Structural and Functional Studies of Biological Macromolecules and Large Macromolecular Complexes

Crystallography Reports - The review describes the application of small-angle scattering (SAS) of neutrons and complementary methods to study the structures of biomacromolecules. Here we cover SAS...     

One-pot five-component high diastereoselective synthesis of polysubstituted 2-piperidinones from aromatic aldehydes,nitriles, dialkyl malonates and ammonium acetate

Molecular Diversity - A novel five-component diastereoselective synthesis of polysubstituted 2-piperidinones is reported. The Knoevenagel condensation–Michael addition–Mannich cascade...     

Purcell Effect and Nonlinear Behavior of the Emission in a Periodic Structure Composed of InAs Monolayers Embedded in a GaAs Matrix

Enhancement of spontaneous emission in a resonant Bragg quantum well (QW) structure with 60 periods of triple InAs monolayers embedded in a GaAs matrix is studied experimentally and theoretically. From measurements of the time‐resolved photoluminescence, besides the QW exciton at 1.47 eV, a specific super‐radiant (SR) emission demonstrating nonlinear properties is found. The SR mode shows a near‐quadratic dependence of intensity on excitation power, while its energy position follows the Bragg condition. It is revealed that the SR mode shows a peculiar non‐monotonic dependence of intensity on direction, with a maximum observed at approximately 40°. The enhancement in the SR emission at a specific direction is correlated well with suggested theoretical consideration of the modal Purcell factor for periodic quantum well structures.     

Effect of reactive stresses on the heat of martensitic transformations in titanium nickelide

Calorimetric studies of titanium nickelide show that thermally reversible prestraining does not affect the heat of the B2 → R and R → B2 martensitic transformations. At the same time, reactive stresses induced by straining under constrained conditions are found to decrease the heat of the B19′ → B2, R → B19′, B2 → R, and R → B2 transformations by a factor of 1.16–1.40. A formula describing this effect is proposed.     

Nanophotonics and nanometrology with planar X-ray waveguide-resonator

The mechanism of X-ray waveguide-resonance propagation or the radiation superstream model, which can become the ground of X-ray nanophotonics, is discussed briefly. Some attention is devoted to features consideration of the simplest devices characterized by the waveguide-resonance transportation of X-ray beams. The experimental data showing the user possibilities of a simplest waveguide-resonators application for diffractometry are presented. We discuss the main reasons to improve the metrological characteristics for total reflection X-ray fluorescence (TXRF) analytical method in case when the target exciting beam is formed by a waveguide-resonator. Some problems appearing during the waveguide-resonator application are formulated.     

The central limit theorem under the absence of extremal absolute order statistics

One finds conditions for the relation are the absolute order statistics for a repeated sample from a symmetric distribution.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 142, pp. 59–67, 1985.     

Effect of diatomite on combustion of poly(vinyl chloride) plastisols

The effect of diatomite on the inflammability, combustibility, and smoke-forming ability of poly(vinyl chloride)-based plastisols has been studied. A substantial decrease in these characteristics takes place upon the introduction of 2–3% diatomite as compared with 10–15% for vermiculite and phlogopite fillers. This phenomenon is associated with a high viscosity of the plastisol melt filled with diatomite and its better foaming and carbonization, along with the formation of a high-porosity coke demonstrating heat-shielding behavior. The use of diatomite also improves the mechanical properties of the tested material.     

On a class of maximally hypoelliptic operators

The maximal hypoellipticity of the operator X ₁ ^2m , ... X _k ^2m is proved, where X_j are first-order pseudodifferential operators and m is a natural number. It is assumed that the set of these operators and their first-order commutators is an elliptic system. The results obtained generalize the well-known results of Hormander, Oleinik, and Radkevich, Kohn, Helffer, and Nourrigat, and Rothshield and Stein. Bibliography: 9 titles. Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 17, pp. 3–26, 1994.     

Law of the iterated logarithm for the quadratic variation of a wiener process

LetP _a be the class of those partitions of intervals [,T], such that |t _i –t _i–1 |>a, wherea is a constant, . It is proved that for anya lim V(T,P _a )/2Tln ₂T=1 a. s., whereln _i x=ln ln x, ifln x e,ln ₂ x=1, ifln x <e.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 158, pp. 72–80, 1987.