Lipid-soluble and water-soluble arsenic compounds in blubber of ringed seal (Pusa hispida)

High concentrations of arsenic were observed in the blubber of ringed seals (Pusa hispida) in our previous study. To better understand the arsenic accumulation in blubber of marine mammals, arsenicals in the blubber of ringed seal were characterized using high performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICPMS). The most predominant water-soluble arsenical in the blubber was dimethylarsinic acid (DMA), in spite of the predominance of arsenobetaine in other tissues. Lipid-soluble fraction was hydrolyzed under mild (tetraethylammonium hydroxide (TEAH) hydrolysis) and strong (NaOH hydrolysis) conditions, and then an aliquot of hydrolysate was injected onto HPLC–ICPMS. Both TEAH-labile and TEAH-stable/NaOH-labile lipid-soluble fractions contained precursors of DMA. These results suggest that the blubber might be the pool of DMA and DMA-containing precursors in ringed seals.     

On square roots of the Haar state on compact quantum groups

The paper is concerned with the extension of the classical study of probability measures on a compact group which are square roots of the Haar measure, due to Diaconis and Shahshahani, to the context of compact quantum groups. We provide a simple characterisation for compact quantum groups which admit no non-trivial square roots of the Haar state in terms of their corepresentation theory. In particular it is shown that such compact quantum groups are necessarily of Kac type and their subalgebras generated by the coefficients of a fixed two-dimensional irreducible corepresentation are isomorphic (as finite quantum groups) to the algebra of functions on the group of unit quaternions. An example of a quantum group whose Haar state admits no nontrivial square root and which is neither commutative nor cocommutative is given.     

Approximate innerness and central triviality of endomorphisms

We introduce the notions of approximate innerness and central triviality for endomorphisms on separable von Neumann factors, and we characterize them for hyperfinite factors by Connes-Takesaki modules of endomorphisms and modular endomorphisms which are introduced by Izumi. Our result is a generalization of the corresponding result obtained by Kawahigashi-Sutherland-Takesaki in automorphism case.     

Supervised scoring models with docked ligand conformations for structure-based virtual screening

Protein-ligand docking programs have been used to efficiently discover novel ligands for target proteins from large-scale compound databases. However, better scoring methods are needed. Generally, scoring functions are optimized by means of various techniques that affect their fitness for reproducing X-ray structures and protein-ligand binding affinities. However, these scoring functions do not always work well for all target proteins. A scoring function should be optimized for a target protein to enhance enrichment for structure-based virtual screening. To address this problem, we propose the supervised scoring model (SSM), which takes into account the protein-ligand binding process using docked ligand conformations with supervised learning for optimizing scoring functions against a target protein. SSM employs a rough linear correlation between binding free energy and the root mean square deviation of a native ligand for predicting binding energy. We applied SSM to the FlexX scoring function, that is, F-Score, with five different target proteins: thymidine kinase (TK), estrogen receptor (ER), acetylcholine esterase (AChE), phosphodiesterase 5 (PDE5), and peroxisome proliferator-activated receptor gamma (PPARgamma). For these five proteins, SSM always enhanced enrichment better than F-Score, exhibiting superior performance that was particularly remarkable for TK, AChE, and PPARgamma. We also demonstrated that SSM is especially good at enhancing enrichments of the top ranks of screened compounds, which is useful in practical drug screening.     

Ferroelectricity and pressure-induced phenomena driven by neutral ionic valence instability of acid-base supramolecules

Supramolecular ferroelectric cocrystals of phenazine (Phz) with chloranilic acid (H(2)ca), bromanilic acid (H(2)ba), and fluoranilic acid (H(2)fa) have been characterized by the interplay between their structural transformations and solid-state acid-base (proton transfer) reactions. At ambient pressure, the Phz-H(2)ca, Phz-H(2)ba, and their deuterated crystals exhibit incomplete proton displacement, which transforms the neutral molecules into semi-ionic at low temperatures below the Curie point (T(c)(IC) < T < T(c)(I)). For the cocrystal of the less acidic H(2)fa, the ferroelectric phase is induced only by applying hydrostatic pressure above ~0.6 GPa. According to the combined studies of temperature-dependent dielectric permittivity and synchrotron X-ray diffraction, it was proved that the ferroelectric (FE-I) phase is always accompanied at lower temperatures by successive phase transitions to the lattice modulated phases with incommensurate periodicities (IC phase, T(c)(II) < T < T(c)(IC)) and with commensurate (2- or 3-fold) periodicities (FE-II or FE-III phase, T < T(c)(II)). Whereas the ground-state structures at ambient pressure are different from one another among the Phz-H(2)ca (FE-II form), Phz-H(2)ba (FE-III form), and Phz-H(2)fa (paraelectric form), their systematic changes under pressure depict a universal pressure-temperature phase diagram. The possible origins of structural changes are assigned to the valence instability and the frustrated Coulomb interactions that induce the charge disproportionation (coexisting neutral ionic) states with the staging spatial orders.     

Extension to velocity dependent gauge transformations

In previous papers it was shown that in phase space a generator of gauge transformations for a singular Lagrangian \(L(q,\dot q)\) is given byG[ε^α]=ε _k ^α φ _α ^k (q,p,t) where φ _α ^k are first class constraints andG is subjected to a stationarity condition. A non-trivial extension from velocity (or momentum) independent gauge transformations to velocity dependent ones is realized, by replacing gauge functions ε^α(t) with momentum dependent functions ε^α(q,p,t), as long asG satisfies the stationarity condition. Inversely, it is proved in a classical framework that, within velocity dependent gauge transformations, all generators of gauge transformations can be expressed in terms of the linear combinations of φ _α ^k .     

P 3-factorization of complete multipartite graphs

In this paper, it is shown that a necessary and sufficient condition for the existence of aP ₃-factorization ofK _m ⁿ is (i)mn 0(mod 3) and (ii) (m – 1)n 0(mod 4).     

The reaction of 1,2-diiodo-tetrafluoroethane with sulfur trioxide

As an extension of our studies on the reaction of I(CF₂CF₂)_nI (n = 2 and 3) with sulfur trioxide¹⁾, the reaction of 1,2-diiodo-tetrafluoroethane with sulfur trioxide was studied.1,2-Diiodo-tetrafluoroethane was reacted with an excess of sulfur trioxide at reaction temperature ranging from 0°C to 115°C.The products were not the expected iododifluoroacetyl fluoride and/ or oxalyl fluoride, but thermally stable derivatives with polysulfate structures.These derivaties could be converted nearly quantitatively into iododifluoroacetyl fluoride and ethyl iododifluoroacetate by potassium fluoride and by ethanol, respectively.The possible structures of these derivatives will be discussed based on these results and ¹⁹F-NMR studies.     

Liquid structure and preferential solvation of metal ions in solvent mixtures of N,N-dimethylformamide and N-methylformamide

Raman spectra of aprotic N,N-dimethylformamide (DMF) and protic N-methylformamide (NMF) mixtures containing manganese(II), nickel(II), and zinc(II) perchlorate were obtained, and the individual solvation numbers around the metal ions were determined over the whole range of solvent compositions. Variation profiles of the individual solvation numbers with solvent composition showed no significant difference among the metal systems examined. In all of these metal systems, no preferential solvation occurs in mixtures with DMF mole fraction of x(DMF) < 0.5, whereas DMF preferentially solvates the metal ions at x(DMF) > 0.5. The liquid structure of the mixtures was also studied by means of small-angle neutron scattering (SANS) and low-frequency Raman spectroscopy. SANS experiments demonstrate that DMF molecules do not appreciably self-aggregate in the mixtures over the whole range of solvent composition. Low-frequency Raman spectroscopy suggests that DMF molecules are extensively hydrogen-bonded with NMF in NMF-rich mixtures, whereas NMF molecules extensively self-aggregate in DMF-rich mixtures, although the liquid structure in neat NMF is partly ruptured. The bulk solvent structure in the mixtures thus varies with solvent composition, which plays a decisive role in developing the varying profiles of the individual solvation numbers of metal ions in the solvent mixtures.