Derivatives of n-(pyrimid-4-yl)ethylamine

In order to find compounds possessing antibacterial activity, a number of new derivatives of N-(pyrimid-4-yl)ethylamine have been synthesized from 5-amino-4, 6-dichloropyrimidine, 2-amino-4, 6-dichloro-pyrimidine, 4, 6-dichloro-2-phenylpyrimidine, and 2,4-dichloro-6-methylpyrimidine and various ethylamines substituted in the -position. Several derivatives of 4-(4-methylpiperazinyl)pyrimidine have also been obtained. Results of a biological study of the compounds obtained are presented.For part II, see ¦1¦.     

H2O and D2O spin-isomers as a mediator of the electron transfer in the reaction center of purple bacteria

The dynamics of charge separation states has been numerically simulated in order to calculate the polarization (in the third order of the perturbation theory) and its evolution in a pulsed optical field. Time evolution of the rotational states of the ortho-D₂O isomer with a nonzero magnetic momentum and mixed ortho/para-D₂O states have been calculated on the basis of the Liouville equation for the density matrix and the Redfield relaxation model for molecular aggregates. Frequencies similar to the known experimental frequencies of the modulation of the kinetics (electron transfer) of the reaction centers special pair in purple bacteria are selected from the set of calculated rotational-resonance frequencies. This semiquantitative coincidence of frequencies (within the experimental error) confirms the previously stated hypothesis, according to which the ortho-H₂O (D₂O) spin isomer can play a role of mediator during electron transfer in the reaction centers of purple bacteria.     

H2O monomers in channels of icelike water structures

We consider the dynamics of H₂O monomers in channels of icelike structures using the model of 1D rotator (i.e., a particle with one translational and one rotational degree of freedom). The effect of the channel walls on the motion of the particle is simulated by the interaction of the dipole moment of the particle with a periodic electric field. In this model, the following four regimes of motion are possible: (i) reflection of the particle from the inlet of the channel; (ii) single passage through the channel with a fixed phase; (iii) passage of the particle through the channel after multiple reflections in the channel from its inlet to its outlet; and (iv) reverse motion of the particle after its stay in the channel and multiple reflections from the inlet and outlet. These regimes indicate the possibility of existence of H₂O monomers in the form of particles trapped in the channels of icelike formations.     

Regenerative amplification of the central component of the Rayleigh line in liquid

It is shown that the Rayleigh scattering signal excited in liquid during four-wave mixing of radiation of diode laser whose frequency difference is tuned in the vicinity of small detunings is amplified in the active element of the probe laser.     

Inverse TERS effect in methyl hydroxyethyl cellulose layers

The Raman scattering signal at the second harmonic (532 nm) of cw Nd:YAG laser in a 0.5-μm-thick methyl hydroxyethyl cellulose film on a gold substrate is found to be attenuated when a platinum-iridium probe (with a tip radius of about 10 nm) of a scanning tunnel microscope is brought close (at a distance of 6 to 8 nm) to the surface. The fluorescence signal barely changes under these conditions.     

Spontaneous symmetry breaking during the switching of a buckled graphene membrane

Switching between the states of a buckled graphene membrane for non-volatile memory applications has been studied. The structure of a zigzag graphene strip bent by a force applied to the central region has been investigated by means of the density functional theory with the use of a B3LYP/6-31G approximation. The initial state of the buckled graphene membrane has the geometry of a segment of a half of a (20,0) carbon nanotube with a length of 5 hexagons. The force has been simulated by sequential displacement of the central atoms of the strip toward the fixed edges of the structure. The dependences of the deformation energy and internal forces on the positions of central atoms have been found. Spontaneous breaking of the membrane symmetry decreasing the energy threshold between the states has been discovered.     

On the theory of electron capture and loss in collisions of accelerated ions

Based on the stationary multichannel scattering theory, the processes of one-electron charge exchange in collisions of multiply charged ions have been considered for the range of high energies of the colliding particles in view of the Coulomb interaction of the nuclei. Numerical calculations have been performed to find the cross-section for electron capture in scattering of high-energy hydrogen-like ions in atomic hydrogen. It has been shown that the Coulomb interaction of nuclei substantially increases the capture cross-section compared to the result predicted by the Brinkmann-Kramers approximation. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 77–81, March, 2008.