On strongly stable normal operators in Krein spaces

For bounded normal operators in Krein spaces we give a necessary and sufficient condition for strong stability. The same result for unitary operators was obtained by M.G.Krein [1] (see also [2]). For selfadjoint operators we refer to the papers of P.Jonas, H.Langer [3] and H.Langer [4].     

Ultraheavy Yukawa-bound states of fourth-generation at Large Hadron Collider

A study of bound states of the fourth-generation quarks in the range of 500?C700 GeV is presented, where the binding energies are expected to be mainly of Yukawa origin, with QCD subdominant. Near degeneracy of their masses exhibits a new ??isospin??. The production of a colour-octet, isosinglet vector meson via $q\bar q \to \omega_8$ is the most interesting. Its leading decay modes are $\pi_8^\pm W^\mp$ , $\pi_8^0Z^0$ , and constituent quark decay, with $q\bar q$ and $t\bar t'$ and $b\bar b'$ subdominant. The colour octet, isovector pseudoscalar ?? ₈ meson decays via constituent quark decay, or to Wg. This work calls for more detailed study of fourth-generation phenomena at LHC.     

Epoxidation of alantolactone and isoalantolactone

Alantolactone and isoalantolactone have been epoxidized with peracetic, m-chloroperbenzoic, and trifluoroperacetic acids. The structure of 4(15)--epoxyisoalactone has been established by an x-ray structural investigation.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 879–884, November–December, 1996. Original article submitted May 20, 1996.     

Crystal and molecular structure of subchrysine (3-O-acetylridentine), a new germacranolide fromArtemisia subchrysolepis

A new sesquiterpenoid lactone was isolated from terrestrial parts ofArtemisia subchrysolepis Filat. and studied by X-ray diffraction analysis and CD spectroscopy. This compound was called subchrysine and identified as (1R,3S,4E,6R,7S)-3-acetoxy-1-hydroxygernmacra-4,10(14), 11(13)-trien-12,6-olide. Pronounced temperature dependence of the¹H and¹³C NMR spectra of subchrysine was observed. The results of conformational analysis of subchrysine by quantum-chemical (PM3) and molecular mechanics (MMX) methods are also presented. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1429–1433, July, 1998.     

Synthesis and antioxidant activity of phenolic derivatives ofα-santonin

Phenolic derivatives of-santonin have been synthesized and their antioxidant effect has been studied.Institute of Phytochemistry, National Academy of Sciences of the Republic of Kazakhstan, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 247–249, March–April, 1997.     

Mass-spectrometric study of 4-azaphenanthrene derivatives

The mass spectra of 15 compounds of the 4-azaphenanthrene series and their deutero analogs with bulky R substituents (R=-CCPh, -CH=CHPh, CHBr-CHBrPh,-CH=CHC₆H₄OCH₃-p, -COOH, -COOC₂H₅, and -CONHNH₂) in the ortho position relative to the nitrogen atom were studied. An intense [M-H]⁺ ion peak, the appearance of which is evidently due to a process involving cyclization of the carbon atom of the side chain with the nitrogen atom, is formed in the fragmentation of the styryl derivatives. The fragmentation of the compounds with a methyl group in the ortho position relative to the styryl grouping is accompanied by the formation of an intense [M-Ph]⁺ ion peak. An ortho effect of the carboxyl and carbethoxy groups adjacent to the methyl substituent is observed in the mass spectra of the investigated compounds. The data obtained make it possible to establish the structures of bulky substituents in the ortho position relative to the ring nitrogen atom and the position of the methyl group in the pyridine ring of monomethylated azaphenahthrenes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 659–665, May, 1979.     

Mass-spectrometric study of methyl-substituted azomethines of the 4-azafluorene series

The M⁺ and [M-H]⁺ ion peaks are the peaks of maximum intensity in the mass spectra of Schiff bases belonging to the 4-aza-9-fluorenylidenearylamine series. The dependence of the relative intensity of the [M-H]⁺ fragment on the structures of the I–XI molecules provides evidence for the possibility of the occurrence of rearrangement processes involving the formation of this ion. The formation of [M-CH₃]⁺, [M-HCN]⁺, [M-Ar]⁺, and [M-CNAr]⁺ ions is also characteristic for the fragmentation of the investigated compounds. It was found that, in contrast to other types of Schiff bases, the ejection of an HCN molecule during the mass-spectrometric fragmentation of the investigated compounds occurs without participation of the nitrogen atom of the azomethine group. The elimination of a CNAr particle by the molecular ions is a distinctive feature of the investigated series of Schiff bases.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 397–402, March, 1979.     

Optical filters with panchromatic emulsion layers for image processing

Amplitude filters with non-linear adaptive performance in the Fourier plane of a mirror optical system are considered. Panchromatic silver bromide layers with a printout effect are employed. The processing of binary and grey-scale images with the aid of a passively adaptive mirror filtering block is investigated.     

SQUID-based measuring systems

A program has been developed and initiated at the Indira Gandhi Centre for Atomic Research (IGCAR) for the utilization of SQUID sensors in various application areas. DC SQUID sensors based on Nb-AlO _x -Nb Josephson junctions have been designed and developed inhouse along with associated flux-locked loop (FLL) electronics. A compact low field SQUID magnetometer insertible in a liquid helium storage dewar has also been developed inhouse and is in use. Efforts to build a high field SQUID magnetometer, SQUID-DAC system, are in progress. A planar gradiometric DC SQUID sensor for non-destructive evaluation (NDE) application to be used in relatively unshielded environment has been designed and developed. An easily portable NDE cryostat with a small lift-off distance, to be used in external locations has been designed and tested. The magnetic field produced by a given two-dimensional current density distribution is inverted using the Fourier transform technique.     

Allobetulin and its derivatives: synthesis and biological activity

This review covers the chemistry of allobetulin analogs, including their formation by rearrangement from betulin derivatives, their further derivatisation, their fusion with heterocyclic rings, and any further rearrangements of allobetulin compounds including ring opening, ring contraction and ring expansion reactions. In the last part, the most important biological activities of allobetulin derivatives are listed. One hundred and fifteen references are cited and the relevant literature is covered, starting in 1922 up to the end of 2010.