Improving virtual screening results with MM/GBSA and MM/PBSA rescoring

Journal of Computer-Aided Molecular Design - Virtual screening (VS) based on molecular docking is one of the most useful methods in computer-aided drug design. By allowing to identify...     

Recyclization of pyrimidinium salts into 1,2,4-triazole derivatives

The interaction of the iodomethylates of pyrimidinyl-2-acetic acid derivatives with monosubstituted hydrazines, in addition to the products of a Kost-Sagitullin rearrangement, leads also to N-substituted triazoles. The structure of the triazoles was demonstrated by NOESY NMR experiments. The structure of the reaction products was determined on the basis of the response observed in the spectra between the methyl group protons of the triazole ring and the spatially close proton of the substituent in position 1 and a conclusion was drawn on the direction of the primary attack of nucleophile in the recyclization process of the pyrimidinium salts into a 1,2,4-triazole. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1175–1179, August, 2007.     

Measurement of the Hydrodynamic Efficiency of Laser Plasma at the “Kanal-2” Installation using Aluminum and Copper Targets

The results of experimental measurements of the hydrodynamic efficiency of laser plasma for aluminum and copper targets are presented. The studies were performed on the “Kanal-2” laser setup system using the ballistic pendulum method. The pressure in the interaction chamber was 10^?4 Torr, the pendulum length was 145 mm, the mass of the pendulum with a target was 7.2 g. At the half-height pulse duration of 2.5 ns, the power density on the target surface was ～10¹³ W/cm². In the case of aluminum target, the hydrodynamic efficiency coefficient increased from 1.5% to 4.5% with increasing laser pulse energy from 5 J to 10 J, whereas it remained at the level of 5% for the copper target.     

Laser-beam-induced current in two-dimensional <Emphasis Type="Italic">n-p-n</Emphasis>-structures

Appearance of a transverse photocurrent at local excitation, by an optical beam, of the surface of n-p-n-structure realized on the basis of a two-dimensional electron gas is studied theoretically. It is shown that the magnitude and sign of the photocurrent depend on the coordinate of the center of light spot. Conditions of linearity of this dependence are found demonstrating the suitability of two-dimensional bipolar structures for use in position-sensitive detectors with high spatial resolution.     

Electron irradiation effects in doped high temperature superconductors YBa2Cu3? x M x O y (M = Fe, Ni; x=0; x =0:01)

The influence of irradiation by electrons with an energy of 8 MeV, at dose intervals between 10¹³ and 2×10¹⁸el/cm², on the properties of impurity doped, high-temperature superconductor YBa₂Cu_3−x M _x O _y (M = Fe, Ni; x=0; x=0:01) ceramics has been studied. It has been established that, as the irradiation dose is increased, the onset temperature of the transition to the superconducting state (T _c ^on ), and the intergranular weak link coupling temperature between granules (T _m ^J ), exhibit an oscillation around their initial values of approximately about 1–1.5 K. This oscillation indicates that the process of radiation defect formation in HTSC occurs in multiple stages. It was also found that the critical current (J _c )decreases with an increase of the irradiation dose, and exhibits a local minimum at a dose of 8×10¹⁶el/cm²coinciding with minima for T _c ^on and T _m ^J at this dose. It was found that the introduction of Fe atoms to the ceramic decreases T _m ^J , while introducing Ni atoms decreases both T _c ^on and T _m ^J ; it is suggested that this is a result of Ni substitution of Cu both in Cu2 plane sites and Cu1 chain sites. The introduction of Ni causes a large change in the intergranular critical current density, J _c . A critical irradiation dose is obtained (2×10¹⁸)after which all HTSC parameters strongly decrease, i. e. the superconductivity of HTSC is destroyed.      

The Kost-Sagitullin Rearrangement in a Series of 1-Alkyl-2-(carbamoylmethyl)-4,6-dimethylpyrimidinium Iodides

The rearrangement of 1-alkyl-2-(carbamoylmethyl)pyrimidinium iodides into substituted 2-alkylaminonicotinamides occurring in alcoholic solutions of amines has been studied. It was shown that in the presence of water the rearrangement of 2-(carbamoylmethyl)-1,4,6-trimethylpyrimidinium iodide is accompanied by the formation of a derivative of 2-oxo-1,2-dihydronicotinic acid, and under the action of ethylamine a rearrangement and transamination occurs leading to 2-ethylamino-4,6-dimethylnicotinamide.