Synthesis of furyl-, furylvinyl-, thienyl-, pyrrolinylquinazolines and isoindolo[2,1-<Emphasis Type="Italic">a</Emphasis>]quinazolines

A method for the synthesis of hydrogenated furyl-, furylvinyl-, thienyl-, and pyrrolinyl-substituted quinazolin-4-ones was developed. A possibility of the reaction of 2-furylquinazolines with maleic anhydride was demonstrated. A number of quinazolines obtained were subjected to a primary bioscreening on inhibition of acetylcholinesterase.     

Opening of the epoxide bridge in 3a,6-epoxyisoindol-1-ones by the action of BF3⋅Et2O in acetic anhydride*

The opening of the epoxide bridge in N-substituted 2,3,7,7a-tetrahydro-3a,6-epoxyisoindol-1-ones by the action of BF₃⋅Et₂O in acetic anhydride at 25°C over 1 h proceeds through an S_N1 mechanism. The allylic type cation formed in the first step is stabilized by the addition of an acetoxy group at C-5 in the isoindole system to give a mixture of cis and trans isomers of 5,6-diacetoxy-2,3,5,6,7,7a-hexa-hydroisoindol-1-ones, which are aromatized under these conditions over 24 h to give 2,3-dihydro-1H-isoindol-1-ones.     

Plasmonic Photoconductive Antennas for Terahertz Pulsed Spectroscopy and Imaging Systems

Optics and Spectroscopy - We propose a terahertz (THz) plasmonic photoconductive antenna (PCA) with a record height of its metal electrodes of h = 100 nm and a high aspect ratio of h/p = 0.5 (p is...     

Wide-Aperture Aspheric Optics for Formation of Subwavelength Caustics of a Terahertz Electromagnetic-Radiation Beam

A wide-aperture aspheric lens for focusing a terahertz electromagnetic-radiation beam in a circle of the subwavelength size is proposed. The calculation of the lens and the estimation of size of created caustic were carried out using computational methods of geometric optics and electrodynamics. The lens is made of high-density polyethylene with the help of a turning machine. For experimental estimation of the spatial resolution provided by the lens, a THz imaging system based on raster scanning of the object’s surface was created. The imaging system was used in combination with wide-aperture THz optics to record images of the streak plates with different spatial frequencies. Analysis of the experimental data showed that the aspheric lens allows the resolution of two objects spaced at a distance of 0.95λ, providing contrast of 15%. The proposed THz optics is superior to classical THz spherical lenses and off-axis parabolic mirrors, greatly expanding the capabilities of THz-spectroscopy methods and imaging.     

Structurally generated elastic nonlinearity of grainy media: Theory and experiment

Nonlinear elastic properties of a grainy medium caused by its structural inhomogeneity are analyzed in this paper. The results of analytical consideration and numerical modeling are compared with the results of known and specially performed experiments. It is shown that the structural mechanism allows us to explain experimental results that remain unexplained within the framework of the concept of elastic nonlinearity related to crystalline lattice anharmonicity.Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, Nos. 1–2, pp. 94–99, January–February, 1995.     

Quasielastic neutrino and antineutrino scattering total cross-sections,axial-vector form-factor

Experimental results on the study of quasielastic reactionsv _μ n→μ ^? p and \(\bar v_u p \to \mu ^ + n\) in the energy range 3–30 GeV are presented in this paper. Spark chamber detector with Al filters has been exposed to the wide-band neutrino and antineutrino beams at Serpukhov. Neutrino and antineutrino data have been used to reconstruct the behaviour of axial-vector form-factorF _A (Q ²). We measured the total cross-sections as a function of energy. The parameterM _A =(1.00±0.04) GeV/c² has been determined under the assumption of the dipole parametrization and CVC hypothesis. Upper limit for the second class currents was estimated.     

MOCVD modification of the surface of multiwalled carbon nanotubes to impart to them necessary physicochemical properties

Multiwalled iron-containing carbon nanotubes were synthesized by the MOCVD method with pyrolysis of ferrocene and toluene mixtures in an argon flow at atmospheric pressure. Using the MOCVD method with vacuum pyrolysis of bis-arene-chromium compounds onto the surface of multiwalled carbon nanotubes (MWCNTs), pyrolytic chromium films were deposited and new composite materials MWCNT/pyrolytic chromium were obtained. The composite morphology depends on the conditions of pyrolytic chromium deposition. Regular bead-shaped structures were detected. The mechanism of their appearance due to the formation of bis-arene chromium compounds of the intermediate viscoplastic polymer phase and the onset of Plateau-Rayleigh instability during pyrolysis is discussed.     

A nonlinear theory for the motion of hydrodynamic discontinuity surfaces

The complete system of hydrodynamic equations that describe the free surface of an inviscid fluid, a tangential discontinuity, and the development of the hydrodynamic instability of a reaction front is reduced to a closed system of surface equations using Lagrangian variables, special integrals of motion, and their analogues. The vorticity is shown to play a fundamental role in the pattern of motion of hydrodynamic discontinuities, imparting a differential form to the equations. In the isentropic approximation, it is demonstrated how to take into account the fluid density oscillations caused by this motion. The derived system of equations is consistent with the previously known analytical solutions obtained in special cases.