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.     

A role for sulfation-desulfation in the uptake of bisphenol a into breast tumor cells

Bisphenol A (BPA) is a widely used plasticizer whose estrogenic properties may impact hormone-responsive disorders and fetal development. In vivo, BPA appears to have greater activity than is suggested by its estrogen receptor (ER) binding affinity. This may be a result of BPA sulfation/desulfation providing a pathway for selective uptake into hormone-responsive cells. BPA is a substrate for estrogen sulfotransferase, and bisphenol A sulfate (BPAS) and disulfate are substrates for estrone sulfatase. Although the sulfated xenobiotics bind poorly to the ER, both stimulated the growth of receptor-positive breast tumor cells. Treatment of MCF-7 cells with BPAS leads to desulfation and uptake of BPA. No BPAS is found inside the cells. These findings suggest a mechanism for the selective uptake of BPA into cells expressing estrone sulfatase. Therefore, sulfation may increase the estrogenic potential of xenobiotics.     

A comprehensive approach to the synthesis of sulfate esters

A comprehensive approach to the synthesis of sulfate esters was developed. This approach permits the direct and high-yielding synthesis of protected sulfate monoesters. Subsequent deblocking to reveal sulfate monoesters is accomplished in near-quantitative yield. The exceptionally stable neopentyl protecting group and the labile isobutyl protecting group were utilized in the synthesis of aromatic and aliphatic sulfate monoesters. Strategies for tuning protecting group reactivity were also explored and developed.     

Synthesis and biological activity of N-sulfonylphosphoramidates: probing the electrostatic preferences of alkaline phosphatase.

N-Sulfonylphosphoramidates have been synthesized to investigate the electrostatic requirements for binding to alkaline phosphatase. Alkyl- and aryl N-benzylated sulfonamides were phosphorylated with bromophosphates or synthesized via phosphoramidite chemistry in moderate yields (44-77%.) The resulting tribenzylated N-sulfonylphosphoramidates may be deprotected in one step to give the free acids in quantitative yields. Physical data of N-sulfonylphosphoramidates, including pK(a)'s and stability toward hydrolysis, were determined. Inhibition data suggests that AP does not bind trianionic N-sulfonylphosphoramidates better than dianionic N-sulfonylphosphoramidates, although N-sulfonylphosphoramidates are bound tighter than N-phenylphosphoramidate. k(cat) for the hydrolysis of N-sulfonylphosphoramidates by bovine and E. coli alkaline phosphatases is 10-60% that of p-nitrophenyl phosphate.     

Synthesis and reactivity of polydisulfonimides.

The first synthesis of alkyl disulfonimide oligomers is presented. In the process of synthesizing these oligomers, previously unreported reactivity of the N-substituted disulfonimide functional group was discovered. Under basic conditions, unexpected lengthening of the oligomers occurs through a "transdisulfonimidation" reaction, whereby new disulfonimides are synthesized from existing ones by reaction with sulfonamide anion. This process appears to proceed via formation of a sulfene intermediate. Support for the E1cB(Rev) mechanism includes isotope scrambling, substituent effects, and sulfene trapping.     

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.