An alternative proof of the extended Saalschütz summation theorem for the r + 3Fr + 2(1) series with applications

A simple proof is given of a new summation formula recently added in the literature for a terminating _{r + 3}F_{r + 2}(1) hypergeometric series for the case when r pairs of numeratorial and denominatorial parameters differ by positive integers. This formula represents an extension of the well‐known Saalschütz summation formula for a ₃F₂(1) series. Two applications of this extended summation formula are discussed. The first application extends two identities given by Ramanujan and the second, which also employs a similar extension of the Vandermonde–Chu summation theorem for the ₂F₁ series, extends certain reduction formulas for the Kampé de Fériet function of two variables given by Exton and Cvijovi? & Miller. Copyright © 2015 John Wiley & Sons, Ltd.     

Steady-state and laser flash photolysis studies on photochemical formation of 4-tert-butyl-4′-methoxydibenzoylmethane from its derivative via the Norrish Type II reaction in solution

A photochemical formation process of avobenzone (AB; 4-tert-butyl-4′-methoxydibenzoylmethane) from 1,1-(4-tert-butybenzoyl)(4′-methoxybenzoyl)butane (PrAB) is studied by steady-state and laser flash photolysis in solution. The quantum yield of the formation via the triplet state of PrAB is determined to be 0.23 in degassed acetonitrile at 295 K. The Arrhenius plots of the decay rate of triplet PrAB show that photoelimination proceeds with an activation energy of 6.0 kcal mol^?1 and the frequency factor of 4.6 × 10¹⁰ s^?1.     

Development of a metabonomic approach based on LC-ESI-HRMS measurements for profiling of metabolic changes induced by recombinant equine growth hormone in horse urine

Despite the worldwide existing regulation banning the use of the recombinant equine growth hormone (reGH) as growth promoter, it is suspected to be used in horseracing to improve performances. Various analytical methods previously developed to screen for its misuse have encountered some limitations in terms of detection timeframes, in particular during the first days following reGH administration. A novel strategy involving the characterization of global metabolomic fingerprints in urine samples of non-treated and reGH-treated horses by liquid chromatography–electrospray–high-resolution mass spectrometry (LC-ESI-HRMS) is described and assessed in this paper in order to develop a new screening tool for growth hormone abuse in horseracing. The strategy involves a limited sample preparation of the urine samples and the use of appropriate software for data processing and analysis. As preliminary work, reproducibility of both sample preparation and mass spectrometry (MS) measurements was evaluated in order to demonstrate the reliability of the method. Application of the developed protocol on two horses demonstrated the suitability of the developed strategy and preliminary results showed significant modifications of the metabolome after treatment with reGH.       

Preparation of allyltin reagents grafted on solid support: clean and easily recyclable reagents for allylation of aldehydes

The preparation of polymer-supported allyltin reagents was shown to be possible for both unfunctionalized and functionalized allyl units. These reagents were treated with aldehydes in the presence of cerium(III) or indium(III) salts to afford high yields of homoallylic alcohols, practically uncontaminated with organotin residues (less than 5 ppm). Some mechanism aspects are briefly discussed and the potential for regeneration and reuse of these supported reagents is pointed out.     

Auto-assembling of ditopic macrocyclic lanthanide chelates with transition-metal ions. Rigid multimetallic high relaxivity contrast agents for magnetic resonance imaging

PhenHDO3A is a ditopic ligand featuring a tetraazacyclododecane unit substituted by three acetate arms and one 6-hydroxy-5,6-dihydro-1,10-phenanthroline group (PhenHDO3A = rel-10-[(5R,6R)-5,6-dihydro-6-hydroxy-1,10-phenantholin-5-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid). This ligand was specially designed so as to obtain highly stable heteropolymetallic assemblies. PhenHDO3A has been prepared starting from phenanthroline epoxide and either a triprotected tetraazacyclododecane or tert-butyl triester of N,N',N' '-tetraazacyclododecane-triacetic acid. The latter yields PhenHDO3A in a single step. PhenHDO3A forms kinetically stable lanthanide complexes (acid-catalyzed kinetic constant kH = (1.2 +/- 0.2) x 10(-3) s(-1) M(-1)) whose solution structure has been deduced from a quantitative analysis of the paramagnetic shifts and the longitudinal relaxation times of the proton nuclei of YbPhenHDO3A. The alcohol group of the dihydro-phenanthroline unit remains coordinated to the encapsulated metal ion despite the steric crowding brought about by this group. Furthermore, the complexes are monohydrated, as shown by luminescence lifetime measurements on EuPhenHDO3A solutions. Relaxivity titrations at 20 MHz clearly indicate that the phenanthroline unit of GdPhenHDO3A is available for the spontaneous formation of highly stable tris complexes with the Fe2+ and Ni2+ ions. The water-exchange times and the rotational correlation times of GdPhenHDO3A and Fe(GdPhenHDO3A)32+ have been deduced from variable temperature 17O NMR studies and from nuclear relaxation dispersion curves. Despite rather slow water-exchange rates (taum0 = 1.0-1.2 x 10(-6) s), relaxivity gains of 90% have been observed upon the formation of the heterometallic tris complexes. The latter rotate about four times more slowly (taur0= 398 ps) than the monomeric unit (taur0 = 105 ps) and their relaxivity is, accordingly, twice as high. The relaxivity of the tris complexes between 10 and 50 MHz is comparable to relaxivities reported for Gd3+-containing dendrimers of much higher molecular weights. The high relaxivity of the tris-PhenHDO3A lanthanide complexes is attributed to their internal rigidity.     

The evaluation of a weighted sum of Gauss hypergeometric functions and its connection with Galton–Watson processes

Lithuanian Mathematical Journal - We evaluate a weighted sum of Gauss hypergeometric functions for certain ranges of the argument, weights and parameters. We establish the domain of absolute...     

Solid-state NMR study of Na versus K doping of para-phenylene oligomers

13C solid-state nuclear magnetic resonance (NMR) experiments were performed on p-terphenyl, p-quaterphenyl, and p-sexiphenyl either in their pristine or doped with alkali metals form. The 13C NMR spectra of doped materials show new resonances by comparison with pristine compounds. For the K-doped materials, these resonances appear in the 90-135 ppm range, while for Na-doped materials, they are observed in the larger 20-150 ppm range. It suggests that the interaction between the alkali ions and the oligomers depends on the nature of the alkali. It is corroborated by 13C NMR experiments after exposure to air that show different behaviors. As expected, air exposure of K-doped samples restores the pristine spectra. This is not the case for Na doping, where the signature of the doped material persists even after exposure to air. In the latter case, some 13C resonances can be assigned to sp3 hybridized carbons and to the quinoid group. It suggests that Na doping induces a polymerization of the oligophenylenes.     

Strain-induced morphologies during homogeneous phase separation in alloys

When precipitates grow with a lattice misfit inside a matrix having cubic crystal symmetry, a transition may occur from an isotropic arrangement of the precipitates to an alignment along the cubic directions of the crystal. Furthermore, if a uniaxial external strain is applied, an additional transition towards tetragonal symmetry can occur by fusion of the precipitates into large plates perpendicular (or long rods parallel) to the direction of applied strain (“rafting”). Recent experiments on Ni-Al-Mo alloys as well as computer simulations relating to these two transitions are reviewed.     

Stereoselective conjugate addition of nitrogen nucleophiles to 3,3,3-trifluoro-1-nitropropene

In order to access 1,2-diamines incorporating perfluorinated groups, the Michael-like addition of nitrogen nucleophiles to 3,3,3-trifluoro-1-nitropropene has been investigated using racemic and optically pure nucleophiles such as amines, amides, oxazolidin(on)es, and thiazolidin(on)es. Complete diastereoselectivity of the addition was achieved with 4-phenylthiazolidine-2-thione.