Generalized Steiner Systems GS(2, 4, v, 2) with v a Prime Power ≡ 7 (mod 12)

Generalized Steiner systems GS(2, 4, v, g) were first introduced by Etzion and were used to construct optimal constant weight codes over an alphabet of size g + 1 with minimum Hamming distance 5, in which each codeword has length v and weight 4. Etzion conjectured that the necessary conditions v 1 (mod 3) and v ; 7 are also sufficient for the existence of a GS(2,4,v,2). Except for the example of a GS(2,4,10,2) and some recursive constructions given by Etzion, nothing else is known about this conjecture. In this paper, Weil's theorem on character sum estimates is used to show that the conjecture is true for any prime power v 7 (mod 12) except v = 7, for which there does not exist a GS(2,4,7,2).     

p-Adic Dynamics and Sullivan's No Wandering Domains Theorem

In this paper we study dynamics on the Fatou set of a rational function . Using a notion of components of the Fatou set defined by Benedetto, we state and prove an analogue of Sullivan's No Wandering Domains Theorem for p-adic rational functions which have no wild recurrent Julia critical points.     

On the structure of the class A(ϕ)

In this paper, we study whether the set A(?) is closed under multiplication f · g, where f and g belong to the class A(?). We also study the problem of the existence of a solution of the equation Bx = C (where B,C ∈ A(?) and B ≠ 0) on the set A(?).     

Expeditious synthesis of helianane and C-10 halogenated heliananes employing ring-closing metathesis

An expeditious synthesis of the marine sesquiterpene helianane enclosing an unusual benzoxocane ring system is described employing ring-closing metathesis as the key step. Helianane has been further converted to the naturally occurring C-10 bromo and chloro derivatives.     

Flow-injection spectrophotometric determination of arylamines and sulphonamides by diazotization and coupling in a micellar medium

In a sodium dodecyl sulphate (SDS) micellar solution, the rate of coupling of a diazonium ion with N-(1- naphthyl)ethylenediamine (NED) increases greatly, the protonation of the resulting azo dyes takes place at higher pH values and the dyes are more soluble. These favourable features were applied to the development of a simple flow-injection spectrophotometric procedure for the determination of diazotizable substances of pharmaceutical interest. Limits of detection in the range 0.2–0.5 μg ml^?1 (signal-to-noise ratio=3), with relative standard deviation of 0.7–3% (n=3) for 5 μg ml^?1 standards, were obtained.     

Precise potential harmonic approach to directly solving Schrodinger equations of helium-like three-body systems

A complete potential harmonic scheme is presented,including the linked coupled hyperradial ordi nary differential equations and the secular equation of eigencnergy It has been used to directly solve the Scchrodinger equations of helium-like three-body systems (nuclear charge Z=1-9),and very accurate ground state eigonenergies as well as low-lying singlet excited state ones have been obtained     

Some less usual properties of tetracyano complexes

The structure and reactivity of one unique molecule may be understood only in relation to its molecular surroundings. The non-stoichiometric forms of the tetracyano complexes M(B) _mM (CN)₄·nG (B=nitrogen or oxygen containing base; G=aromatic compound or H₂O,m0,n>0) are understood in this respect. Their stoichiometric or non-stoichiometric forms, with voids either completely or more often partially occupied, are responsible for their observed sorptive and resorptive abilities. The effects of the surroundings are correlated with the results of thermal analysis, magnetic measurements and their sorptive abilities.Dedicated to Professor H. M. Powell.     

Thermodynamic behavior of polyelectrolytes with the lower critical solution temperature (LCST) phenomenon

A series of vinyl polymers with L-valine and L-leucine residues, and related copolymers with N-isopropylacrylamide, were studied in aqueous solution at different temperatures (25, 30 and 35°C) and at two ionic strengths (0.01 M and 0.1 M NaCl). The protonation behavior revealed great differences between the polymers that were attributed to the size of the hydrophobic lateral group. Macromolecular shrinkage, occurring above a critical degree of protonation β, was related to hydrophobic forces outweighing the electrostatic repulsions between COO – groups. Low salt concentrations increased the electrostatic potential while high temperatures increased the hydrophobic interaction at lower β. The release of fewer water molecules structured around the polymer chain, responsible for the lower critical solution temperature phenomenon, revealed lower entropy changes at higher temperatures. The reversible configuration of graft polymer chains instantly responded to changes in pH and temperature, modifying the water filtration rates through the pores of cellulose membranes.     

Flow injection on-line ultrasound-assisted extraction of iron in meat samples coupled to a flame atomic absorption spectrometric system

Iron was extracted on-line from solid meat samples by a simple and rapid continuous ultrasound-assisted extraction system (CUES). The CUES is connected to a flow injection manifold, which allows the on-line flame atomic absorption spectrometric determination of iron. A Plakett–Burman design was used for the optimisation of the CUES. The method achieved a total sampling frequency of 11 samples per hour with a relative standard deviation for the complete procedure of 0.4%. The detection limit was 0.6 g g^–1 (dry mass) for a sample amount of 30 mg. Accurate results were obtained by measuring the certified reference materials BCR-186 (pig kidney) and BCR-184 (bovine muscle). The analytical procedure was applied to different real meat samples with satisfactory results.     

Atomic Force Microscopy,Transmission Electron Microscopy,and Photon Correlation Spectroscopy: Three Techniques for Rapid Characterization of Optimized Self-Nanoemulsiying Drug Delivery System of Glibenclamide,Carvedilol, and Lovastatin

This article looks at atomic force microscopy as an important aid to characterize the self-nanoemulsifying formulation of glibenclamide, lovastatin, and carvedilol in conjunction with other sophisticated technique, viz., transmission electron microscopy and photon correlation spectroscopy. Sizes obtained by processing the atomic force microscopy (AFM) image are comparable with those obtained from transmission electron microscope. Although in the present study, the mean particle size obtained from photon correlation spectroscopy does not correlate to the findings of atomic force microscopy and transmission electron microscopy, but the poly-disperse index values correlate well with the findings of AFM and transmission electron microscopy where uniform particle size was observed in aqueous dispersion of self-nanoemulsifying formulation of glibenclamide, lovastatin, and carvedilol.