Can the morphology of γ-ray emission distinguish annihilating from decaying dark matter?

Recent results from the PAMELA, ATIC, FERMI and HESS experiments have focused attention on the possible existence of high energy cosmic rays e+ e- that may originate from dark matter annihilations or decays in the Milky Way. Here we examine the morphology of the associated γ-ray emission after propagation of the electrons generated by both annihilating and decaying dark matter models. We focus on photon energies of 1, 10, and 50 GeV (relevant for the FERMI satellite) and consider different propagation parameters. Our main conclusion is that distinguishing annihilating from decaying dark matter may only be possible if the propagation parameters correspond to the most optimistic diffusion models. In addition, we point to examples where morphology can lead to an erroneous interpretation of the source injection energy.     

Synthesis and binding ability of mono- and tetrasubstituted aminophosphonate Zn-tetraarylporphyrins towards N- and O-containing organic substrates

The 1,6-addition of mono- and tetra-amino 5,10,15,20-tetraphenylporphyrins with dimethyl-(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidenemethyl)phosphonate leads to the corresponding mono- and tetrasubstituted aminophosphonate porphyrin derivatives. The binding ability of their Zn(II)-complexes towards 1,4-diazabicyclo[2,2,2]octane, imidazole, 4-(1H-imidazole-1-yl)benzyl alcohol and 4-(1H-imidazole-1-ylmethyl)benzyl alcohol in toluene was investigated by spectrophotometric and ¹H NMR titration. It has been determined that the monosubstituted Zn-tetraarylporphyrin is involved in a two-point selective binding of 4-(1H-imidazole-1-ylmethyl)benzyl alcohol. Taking into account the fact that this binding is accompanied by a clear and easily identifiable response in the UV–vis spectra of the reaction mixture, this metalloporphyrin could be considered as a molecular optical sensing device for selected bidentate N- and O-containing substrates.     

Cold N+NH collisions in a magnetic trap

We present an experimental and theoretical study of atom-molecule collisions in a mixture of cold, trapped N atoms and NH molecules at a temperature of ～600 mK. We measure a small N+NH trap loss rate coefficient of k(loss)(N+NH)=9(5)(3)×10(-13) cm(3)?s(-1). Accurate quantum scattering calculations based on ab initio interaction potentials are in agreement with experiment and indicate the magnetic dipole interaction to be the dominant loss mechanism. Our theory further indicates the ratio of N+NH elastic-to-inelastic collisions remains large (>100) into the mK regime.     

Complexes of Chlorin e6 with Pluronics and Polyvinylpyrrolidone: Structure and Photodynamic Activity in Cell Culture

Polymeric carriers are extensively used in photodynamic therapy (PDT) for increase of efficacy of photosensitizers. Here, we report the influence of nine Pluronic copolymers on phototoxicity of chlorin e6 (Ce6), in particular 5‐ to 7‐fold rise in the phototoxicity caused by hydrophilic Pluronics F127, F108, F68 and F87 and practically no influence on Ce6 of more hydrophobic polymers. The revealed value of 0.2 mg mL^?1 of Pluronic F127 concentration sufficient for half‐of‐maximal increase of Ce6 photodynamic activity proved to be close to 0.16 mg mL^?1 inherent in well‐documented carrier poly(N‐vinylpyrrolidone) (PVP). The dissociation constants of Ce6 complexes with Pluronic F127 and PVP that were estimated from UV spectra were 0.252 and 0.036 mg mL^?1, respectively, indicating higher stability of Ce6 complex with PVP. According to the results of ¹H‐NMR studies of Ce6 complexes, the porphyrin interacts not only with hydrophobic regions but also with hydrophilic sides of both polymers.     

Methionine ligand lability of type I cytochromes c: detection of ligand loss using protein film voltammetry

Protein film voltammetry (PFV) is used to interrogate the behavior of a variety of bacterial and mitochondrial His/Met-ligated cytochromes c. While analogous studies upon alkanethiol-modified gold electrodes reveal the anticipated Fe(II/III) couple only, PFV using pyrolytic graphite edge (PGE) electrodes demonstrates the presence of a lower-potential form of each of the cyts c studied, with a potential of approximately -100 mV (vs hydrogen). The generation of the novel, lower-potential state is shown to arise specifically from the interaction with the PGE electrode. Simultaneously, the typical Fe(II/III) couple can be observed. PFV of a series of wild-type cytochromes and mutants in the Met-donating loop show that the lower-potential state is highly similar between proteins from Pseudomonas aeruginosa (PA), Hydrogenobacter thermophilus (HT), and horse heart. The generation of the lower-potential form correlates inversely with the stability of the Met-Fe interaction for each of the cytochromes. Comparison with chemically unfolded cyts c indicates that the lower-potential forms detected here are unique, and this distinct state is ascribed to the loss of the Met ligand. Thus, PGE is demonstrated to be a non-innocent electrode surface in PFV studies of His/Met-ligated cytochromes c.     

A validated LC–MS/MS method for fast detection of thiodiglycolic acid in aqueous samples

A novel sensitive screening method based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) has shown the feasibility of separation and detection of thiodiglycolic acid in aqueous samples. The analysis of this compound is of interest since it is specific microbiological metabolite of thiodiglycol, which is precursor and degradation product of chemical warfare agent sulfur mustard. The LC–electrospray ionisation (ESI)–MS method provides a sensitive and direct approach for thiodiglycolic acid identification and quantification using non-extracted non-derivitised samples from aqueous solutions. Chromatographic separation of the thiodiglycolic acid was produced using a reverse phase LC column with gradient mobile phases consisting of 0.1% formic acid in water and acetonitrile. Identification and quantification of species were achieved using ESI–tandem MS monitoring two precursor-to-product ion transitions for thiodiglycolic acid. The method demonstrates linearity over at least two orders of magnitude and detection limit of 10 ng...mL^–1 in environmental water samples.