Path integral quantization corresponding to the deformed Heisenberg algebra

In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result.     

Wavelength-scanning Talbot effect and its application for arbitrary three-dimensional step-height measurement

We demonstrate the phenomenon of Talbot self-image plane shift by tuning the wavelength of the broadband light source. A superluminescent diode (SLD) is used as a broad-band light source and an acousto-optic tunable filter (AOTF) as wavelength-scanning device. A periodic grating is illuminated by the wavelength tuned light of SLD using AOTF and Talbot self-image plane is shifted continuously in the longitudinal direction without mechanically moving the grating. The wavelength-scanning Talbot effect is then implemented for the measurement of arbitrary step-height of discontinuous objects with extended range. The main advantages of the proposed system are non-mechanical scanning, high stability because of it’s common-path geometry and compactness. Since the measurement of the phase is not required the system is free from phase ambiguity problem and therefore, the range of measurement is large as compare to interferometric techniques.     

Working group report: Neutrino and astroparticle physics

This is the report of neutrino and astroparticle physics working group at WHEPP-7. Discussions and work on CP violation in long baseline neutrino experiments, ultra high energy neutrinos, supernova neutrinos and water Cerenkov detectors are discussed.     

Z decay constraints on supersymmetric particles revisited

The allowed regions in the chargino-gluino mass plane are mapped out using the latestZ decay data from experiments. The determination of these masses in future experiments will uniquely fix the neutralino mass spectrum for a fixedv ₁/v ₂. Since the usual two-fold ambiguity is removed by LEP data for gluino masses upto 200 GeV. Constraints have also been placed on neutralino masses.     

Electron transfer reactions of nickel(III) and nickel(IV) complexes

This review narrates the electron transfer reactions of various nickel(III) and nickel(IV) complexes reported during the period 1981 until today. The reactions have been categorized mainly with respect to the type of nickel complexes. The reactivity of nickel(III) complexes of macrocycles, 2,2′-bipyridyl and 1,10-phenanthroline, peptides and oxime–imine, and of nickel(IV) complexes derived from oxime–imine, oxime and miscellaneous ligands with various organic and inorganic electron donors have been included. Kinetic and mechanistic features associated with such interactions have been duly analyzed. The relevance of Marcus cross-relation equations in the delineation of the electron transfer paths has also been critically discussed.     

Polyelectrolyte behavior and macromolecular properties of sodium amylopectin xanthate in dilute solution

Sodium amylopectin xanthate was prepared by xanthation of potato amylopectin in alkaline medium. The pure product was characterized by I₂ solution and ultraviolet spectra of the xanthate groups. The polyelectrolyte behavior of Na amylopectin xanthate in aqueous and salt solutions was investigated by viscometry and light scattering. Its polyelectrolyte behavior in aqueous solution as studied viscometrically was completely different from that of Na amylose xanthate, which is characteristic of linear polyelectrolyte molecules. This difference in behavior could be partly due to the branched structure of amylopectin molecule. A dissymmetry study of Na amylopectin xanthate in aqueous and salt solutions, however, showed that Na amylopectin xanthate molecule underwent expansion in water by about 1.3 times its linear dimension in 0.5M NaCl (unperturbed value). Light-scattering measurements confirmed that the Na amylopectin xanthate molecule had a polydisperse random-coil chain configuration in 0.25M NaCl. Its molecular weight, end-to-end length, and other parameters in salt and alkali solutions were also determined, and the data were then compared with those of Na amylose xanthate in the same media. The solution behavior of Na amylopectin xanthate in 1M NaOH was further investigated and linear expansion factor α, excluded volume factor A₂M _W/[η], and Flory's hydrodynamic constant φ were evaluated.     

Mechanism of azole antifungal activity as determined by liquid chromatographic/mass spectrometric monitoring of ergosterol biosynthesis

A liquid chromatography/mass spectrometry (LC/MS) method for separation and characterization of ergosterol biosynthetic precursors was developed to study the effect of Posaconazole on sterol biosynthesis in fungi. Ergosterol biosynthetic precursors were characterized from their electron ionization mass spectra acquired by a normal-phase chromatography, particle beam LC/MS method. Fragment ions resulting from cleavage across the D-ring and an abundant M - 15 fragment ion were diagnostic for methyl substitution at C-4 and C-14. Comparison of the sterol profile in control and treated Candida albicans incubations showed depletion of ergosterol and accumulation of C-4 and C-14 methyl-substituted sterols following treatment with Posaconazole. These C-4 and C-14 methyl sterols are known to be incapable of sustaining cell growth. The results demonstrate that Posaconazole exerts its antifungal activity by inhibition of ergosterol biosynthesis. Furthermore, Posaconazole appears to disrupt ergosterol biosynthesis by inhibition of lanosterol 14alpha-demethylase.     

Physicochemical and macromolecular properties of sodium amylose xanthate in dilute solution

Sodium amylose xanthate has been studied in dilute solution. Potato starch was fractionated for this purpose into amylose and amylopectin fractions. Amylose was xanthated in solution under alkaline conditions and the Na amylose xanthate was then characterized by reaction with I₂ solution and ultraviolet spectra of the xanthate groups determined. Stability of the xanthate in alkaline condition under both oxygen and nitrogen atmospheres was also investigated. From light scattering measurements of dilute salt solutions of Na amylose xanthate, the weight-average molecular weight M _w as well as the molecular dimensions were determined. In 0.11M NaCl, which conforms to the θ solvent, Na amylose xanthate molecules appear to have a random-coil configuration. Two other configurational parameters, such as the effective bond length b, and the steric factor σ, i.e., (R₀²)^1/2/(R_f² )^1/2, where (R₀²)^1/2 is the Root-mean-square end-to-end distance in the unperturbed state and (R_f² )^1/2 is the unperturbed value calculated on the assumption of free rotation about each intermonomer C? O bond of the amylose chain were also calculated and found to be 6.24 and 1.020, respectively. It is thus concluded that the amylose chain in Na amylose xanthate behaves as a typical flexible coil in dilute salt solution.     

Zeolite-mediated photochemical charge separation using a surface-entrapped ruthenium-polypyridyl complex

Employing the strategy of quaternization of the 2,2' N atoms of the conjugated bipyridine ligand 1,4-bis[2-(4'-methyl-2,2'-bipyrid-4-yl)ethenyl]benzene (L), a polypyridyl complex of ruthenium(II) was tethered on the surface of zeolite Y. Electrochemical and spectroscopic properties of the complex suggest that, upon visible photoexcitation of the MLCT band, the electron is localized on the conjugated ligand rather than the bipyridines. Electron transfer from the surface complex to bipyridinium ions (methyl viologen) within the zeolite was observed. Visible light photolysis of the ruthenium-zeolite solid ion-exchanged with diquat and suspended in a propyl viologen sulfonate solution led to permanent formation of the blue propyl viologen sulfonate radical ion in solution. The model that is proposed involves intrazeolitic charge transfer to ion-exchanged diquat followed by interfacial (zeolite to solution) electron transfer to propyl viologen sulfonate in solution. Because of the slow intramolecular back-electron-transfer reaction and the forward electron propagation via the ion-exchanged diquat, Ru(III) is formed. This Ru(III) complex formed on the zeolite is proposed to react rapidly with water in the presence of light, followed by reaction with the propyl viologen sulfonate, to form pyridones and regeneration of Ru(II), which then continues the photochemical process.     

Time-resolved spectroscopy of solid poly(1-vinyl naphthalene)following electron beam pulse radiolysis: pulse radiolytic studies on polymers

Transient emission studies following pulse radiolysis of solid poly(1-vinyl naphthalene) show existence of excited monomers and two excimers. Quenching experiments indicate that excimers are not formed directly by recombination of ions but probably by trapping of migrating monomeric excitation in performed traps whose density is approximately one in 10³.