Electromagnetic field representation in the source region

Representation of electromagnetic fields in the source region in inhomogeneous anisotropic media is developed in terms of Hertz vectors. Differential equations satisfied by these vectors as functions of stream potentials of the sources are obtained. Conditions for representation in terms of uncoupled transverse electric and magnetic modes satisfying second-order differential equations are derived.     

Frequency conversion and amplification by stimulated electromagnetic shock radiation (SESR)

The coherent response of a polarizable medium to the radiation stimulated by the interaction of an incident coherent electromagnetic wave with a charged-particle beam, moving with greater than critical speed, results in intense electromagnetic radiation in the form of one or more shock fronts. The shock frequencies are shifted significantly from that of the incident wave and are tunable by parametric variation of the incident beams. The mechanism for this new effect (SESR) differs fundamentally from the laser mechanism. Production of intense quasi-coherent x-ray radiation by SESR obviates the need for x-ray mirrors and is not inhibited by the large spontaneous emission rates at these frequencies. Substantial fraction of the particle-beam energy can be converted into frequency-shifted radiation, with intensity larger than that of the incident wave, because of quadratic dependence on the interaction distance in the medium of the energy radiated into SESR, as compared to the linear dependence of Cerenkov radiative energy. Specific shock frequencies cross from below to above a given resonance frequency of the medium as the relevant two level populations become inverted. This dynamical dependence of the shock frequencies on the level populations provides the basis for new pumping and amplification mechanisms. An example of a possible SESR-based transducing-amplification system is described.     

Growth of a nonuniform ripple on a Gaussian beam in a plasma

In the present paper we have investigated the growth of a radially symmetrical ripple, superimposed on a Gaussian beam propagating in a plasma. The effect of the position and the width of the ripple on its growth has been studied in some detail. The present analysis considers two mechanisms for the redistribution of carriers in the plasma and the effect of redistribution on the growth of the ripple; the two mechanisms are nonuniform collision dominated heating of the carriers and the ponderomotive force arising on account of nonuniform intensity distribution. Work supported by NSF (USA) and CSIR (India).     

Higher-order wave interactions in a periodic medium

A singular perturbation analysis of the interaction of the fundamental plane wave progressing in the direction of the sinusoidally varying permittivity of an unbounded medium with the first four space harmonics progressing in the reverse direction is carried out. The periodic inhomogeneity introduces self and mutual interaction phenomena. The self interaction, in general, produces a phase shift and causes the mutual interaction to occur for frequencies higher than those predicted by the Bragg condition. The mutual interaction introduces a complex change in the wavenumber resulting in the interacting waves becoming evanescent. Analytical expressions for the frequency shift and the other wave characteristics in the interaction region are deduced. With the increase in the order of the interaction, the frequency shift becomes a more dominant effect than the wave evanescence.     

Reactions of γ-Sultines with Electrophilic Reagents. 2. Bromination of 3,5-Diaryl-1,2-oxathiolane 2-Oxides in the Presence of Lewis Acids

The bromination of 3,5-diaryl-1,2-oxathiolane 2-oxides (84h703324u501/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-sultines) has been studied in the presence of added Lewis acids. It was discovered that 84h703324u501/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-sultines with donor substituents react with bromine with ring fission and conjugated addition of the nucleophilic reactant. Possible mechanisms for the reaction are discussed based on the data obtained.     

A new synthetic route to compounds of the AFDX-type with affinity to muscarinic M2-receptor

[3-(1,3-Dioxo-1,3-dihydroisoindol-2-yl)-propyl]dimethyl-{6-[(1-{2-[(6-oxo-5,6-dihydro-benzo[e]pyrido[3,2-b][1,4]diazepine-11-carbonyl)amino]ethyl}piperidin-2-yl-methyl)-propylamino]hexyl}ammonium bromide a hybride containing a fragment of the antagonist of muscarinic receptor AFDX-384 and a W84 moiety known as allosteric modulator of antagonist binding, was synthesized in a divergent synthesis starting from pipecolic acid, phthalic anhydride and 3-amino-2-chloropyridine. This new microwave assisted route is very convenient and allows to modify the piperidine ring, the benzodiazepine system, the phthalimide moiety and the chains connecting the ring systems. Yields and reproducibility were satisfying.     

Synthesis of New Cyclophane Host Molecules and Crystal Structures of Their Compounds with Hydrocarbon Guests

Three new cyclophane host molecules 2, 4, and 6 are prepared by connecting the oxygen atoms of two84/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> ,84/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">'–di(4-hydroxyphenyl)-1,4-diisopropylbenzene units with two di-, tetra-, and hexamethylene spacers, respectively. Solid-state structures are determined for host 2 with a hexane guest, host 4 with a toluene guest and a solvating toluene molecule, host 4 with a p-xylene guest,and host 6 with two p-xylene guests.     

Essential Oil Constituents of Satureja boissieri from Turkey

Water-distilled essential oil from the aerial parts ofS. Boissieriwas analyzed by GC/MS. Forty - five components were characterized representing 97% of the oil. The main components were identified as carvacrol (40.8%),84u496668g31/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-terpinene (26.4%), andp-cymene (14.5%).