Preparative isolation of (+)-beta-eudesmol fromAmyris balsamifera

Summary Optically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum distillation of the total oil. Step two was a medium pressure LC separation with an AgNO₃ impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related sesquiterpene alcohols (75% of the oil).     

Cosmic rays as a new instrument of seismological studies

The state of the art of the short-termearthquake prediction problemis considered. A new method for monitoring the 3D stress state in the earthquake-prone zone using high-energy muons in cosmic rays and simultaneous measurements of acoustic and seismic signals in the frequency range from 1 Hz to 1–2 kHz is proposed. To implement this method, muons should be detected simultaneously with extensive air showers in an area of several square kilometers.     

Investigation of the electrophilic reactions of 2-benzyl-3-hydroxypyridine and its N-oxide

A comparative investigation of the aminomethylation, azo coupling, and iodination of 2-benzyl-3-hydroxypyridine and its N-oxide has shown that the N-oxide group affects the orientation of iodination but does not affect the direction of aminomethylation and azo coupling. The structures of the newly synthesized compounds were confirmed by the IR and PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 518–520, April, 1973.     

Asymptotic completeness of scattering in the nonlinear Lamb system for nonzero mass

We establish the asymptotic completeness in the nonlinear Lamb system with nonzero mass for hyperbolic stationary states. For the proof, we construct a trajectory of a reduced equation (which is a nonlinear nonautonomous ODE) converging to a hyperbolic stationary point, using the Banach space Inverse Function Theorem and a priori estimates. We give a counterexample showing that the hyperbolicity condition is essential.     

Scattering in the nonlinear Lamb system

We obtain long time asymptotics for the solutions to a string coupled to a nonlinear oscillator: each finite energy solution decays to a sum of a stationary state and a dispersive wave. The asymptotics hold in global energy norm. The dispersive waves are expressed via initial data and solution to an ordinary differential equation. The asymptotics give a mathematical model for the Bohr's transitions between quantum stationary states.     

On the Neumann problem for the Helmholtz equation in a plane angle

We prove that the solution of the Neumann problem for the Helmholtz equation in a plane angle Ω with boundary conditions from the space H_−1/2(Γ), where Γ is the boundary of Ω, which is provided by the well‐known Sommerfeld integral, belongs to the Sobolev space H₁(Ω) and depends continuously on the boundary values. To this end, we use another representation of the solution given by the inverse two‐dimensional Fourier transform of an analytic function depending on the Cauchy data of the solution. Copyright © 2000 John Wiley & Sons, Ltd.     

Evidence of suprathermal electron fluxes in laser-produced plasma from the polarization and anisotropy of X-ray bremsstrahlung emission

Polarization and angular distribution of suprathermal X-ray emission from plasma produced by picosecond ruby laser pulses have been measured. Polarization of 12 ± 3 percent and anisotropy of X-ray angular distribution evidence the existence of suprathermal electron fluxes in plasma. Their direction corresponds to resonance absorption mechanism.