Non-adiabatic calculation of muonic atom-nucleus collisions

In order to calculate the cross sections of the muonic atom-nucleus collisions, we have proposed a precise numerical method, a non-adiabatic coupled-rearrangement-channel method with the use of the Jacobian coordinates for the three-body system in the whole space. The scattering boundary condition is correctly imposed along the coordinates; this method does not suffer from the well known defects of the method of adiabatic representation. We applied our method to the muonic atom-nucleus collisions for an incident c.m. energies of 0.001–100 eV.     

Resonance energies of meta-stable dtµ*

Using the coupled rearrangement channel method, we have calculated resonance energies for meta-stable states of the molecular ion dtµ^* associated with the adiabatic 3 potential. The vacuum polarization effect was taken into account by direct inclusion of the Uehling potential in our three-body Hamiltonian. Comparing with the solution of the pure Coulombic Schrödinger equation a shift of approximately +0.1 eV is found. Thus the infinite series of states of the Coulombic Schrödinger equation becomes truncated. Eleven states remain semi-bound, five of them with binding energy smaller than the dissociation energy of the D₂ molecule, facilitating formation of dtµ^* in tµ(2s)-D₂ scattering by means of the Vesman-mechanism.     

Base-mediated cyclization reaction of 2-alkynylphenylphosphine oxides: synthesis and photophysical properties of benzo[b]phosphole oxides

The base-mediated intramolecular cyclization reaction of 2-alkynylphenylphosphine oxides affords benzo[ b]phosphole oxides, which show intense blue-green fluorescence. Benzo[ b]phospholes are also prepared by the reduction of benzo[ b]phosphole oxides.     

Simultaneous determination of YM928, a novel noncompetitive AMPA receptor antagonist, and its demethylated metabolite in rat, dog and monkey plasma by high-performance liquid chromatography with ultraviolet detection

A specific HPLC method for the simultaneous determination of YM928, a novel noncompetitive AMPA receptor antagonist, and its demethylated metabolite (YM-58875) in rat, dog and monkey plasma was developed and validated. The method utilized multiple-step liquid-liquid extraction followed by a reversed-phase HPLC with UV detection at 275 nm. No interfering peaks were observed at the retention times of YM928, YM-58875 or internal standard. The validated quantitation range was 5-5000 ng/mL for both YM928 and YM-58875 when 1 mL of the plasma sample was used. The intra- and inter-day precision was less than 5.3 and 2.5% for YM928, and 3.7 and 2.3% for YM-58875, respectively. The intra- and inter-day accuracies were -8.7-5.3% and 0.7-1.9% for YM928, and -10.0-6.1% and 1.3-3.4% for YM-58875, respectively. The mean recoveries in the extraction process were 52.7-62.8%. The utility of this analytical method was demonstrated by the investigation of the pharmacokinetics of the unchanged drug and its metabolite in preclinical studies.     

40]nonaphyrin(1.1.1.1.1.1.1.1.1) and its heterometallic complexes with palladium-carbon bonds

meso-Pentafluorophenyl- substituted [40]nonaphyrin(1.1.1.1.1.1.1.1.1) 3 has been prepared by using a stepwise ring-size-selective synthesis, and has been reduced with NaBH(4) to [42]nonaphyrin(1.1.1.1.1.1.1.1.1) 5. Structurally, 3 is characterized by a figure-of-eight shape, consisting of a porphyrin-like tetrapyrrolic segment and a hexaphyrin-like hexapyrrolic segment, whereas 5 has been found to adopt a distorted nonplanar butterfly-like shape. In the mono-metal complexes 6 and 7, a Zn(II) or Cu(II) ion is bound by the porphyrin-like tetrapyrrolic segment, maintaining the overall structure of 3. Similarly to 3, complexes 6 and 7 are interconvertible with the corresponding complexes 9 and 10 through two-electron reduction with NaBH(4) and oxidation with DDQ. The metal-free hexaphyrin-like segments of 6 and 7 have been shown to serve as a suitable platform for the complexation of two palladium ions, providing hetero-trinuclear metal complexes 11 (Zn(II)-Pd(II)-Pd(II)) and 13 (Cu(II)-Pd(II)-Pd(II)) in high yields, in which the Zn or Cu ion resides at the same porphyrin-like segment, and one Pd ion is bound in an NNCC fashion through double C--H bond activation while the other is bound in an NNC fashion with single C--H bond activation. Multi-metal complexes 11, 12, and 13 exhibit small electrochemical HOMO-LUMO gaps (<0.6 eV), despite their nonplanar conformations.     

Single-Round DNA Aptamer Selection by Combined Use of Capillary Electrophoresis and Next Generation Sequencing: An Aptaomics Approach for Identifying Unique Functional Protein-Binding DNA Aptamers

In DNA aptamer selection, existing methods do not discriminate aptamer sequences based on their binding affinity and function and the reproducibility of the selection is often poor, even for the selection of well-known aptamers like those that bind the commonly used model protein thrombin. In the present study, a novel single-round selection method (SR-CE selection) was developed by combining capillary electrophoresis (CE) with next generation sequencing. Using SR-CE selection, a successful semi-quantitative and semi-comprehensive aptamer selection for thrombin was demonstrated with high reproducibility for the first time. Selection rules based on dissociation equilibria and kinetics were devised to obtain families of analogous sequences. Selected sequences of the same family were shown to bind thrombin with high affinity. Furthermore, data acquired from SR-CE selection was mined by creating sub-libraries that were categorized by the functionality of the aptamers (e. g., pre-organized aptamers versus structure-induced aptamers). Using this approach, a novel fluorescent molecular recognition sensor for thrombin with nanomolar detection limits was discovered. Thus, in this proof-of-concept report, we have demonstrated the potential of a “DNA Aptaomics” approach to systematically design functional aptamers as well as to obtain high affinity aptamers.     

Structural assignment of n3-acylated uridine derivatives by means of 13c nmr spectroscopy

Diisopropylethylamine was effective as a base for acylation of 2′,3′,5′-tri-O-acetyluridine with various acid chlorides. The ¹³C NMR spectra of the products and related compounds showed clearly that the acyl groups intoduced to the uracil moiety are attached to the N³-nitrogen.     

A convenient stereoselective synthesis of β-lactams from β-hydroxy-α-thioalkylesters prepared from Michael/aldol tandem reaction or stereoselective addition of thiols to the Baylis-Hillman adducts

A convenient stereoselective synthesis of β-lactams from thio-Michael/aldol tandem adduct is described. syn-Selective tandem reaction followed by amidation and intramolecular S_N2 reaction provided β-lactams in diastereomerically pure form. The tandem reaction with aliphatic aldehydes, on the other hand, afforded a mixture of diastereomers of corresponding tandem adducts in about 3:1 ratio so that the conversion to β-lactams afforded a diastereomeric mixture. As an alternative approach to prepare the tandem adducts, the stereoselective Michael addition of aliphatic thiols to Baylis-Hillman adduct was developed. The stereoselectivity was sensitive to the protective group at the hydroxyl group and TBS protection brought the most successful syn-selective formation of the tandem adducts. The procedure could be applied to the ketone derivatives of the Baylis-Hillman adduct but no selectivity was observed for the nitrile-Baylis-Hillman adducts. A similar conversion of the adduct provided desired β-lactams stereoselectively.     

Uptake and Reduction of Arsenate by Dunaliella sp.

Uptake and reduction of arsenate [AS(V)] by Dunaliella sp. cells were determined to investigate the metabolic processes of arsenic in the alga. Cellular uptake of arsenic by Dunaliella sp. cells was markedly affected by the form of arsenic in the medium. The content of arsenic taken up by Dunaliella sp. cells increased rapidly with time on addition of As(V) to the medium. However, in the case of addition of arsenite [As(III)], the gradient of arsenic uptake by Dunaliella sp. cells was low, and arsenic content was small. In the water-soluble fraction of arsenic taken up by Dunaliella sp. cells with exposure to As(V), arsenic was in the forms of organic arsenic, As(V) and As(III). The content of As(V) in the water-soluble fraction increased with exposure time. The content of As(III) also increased with time, but remained constant after 5 h of exposure. On the other hand, organic arsenic content was small and did not increase with time. It was found that Dunaliella sp. takes up As(V) and readily reduces it to As(III)