Fluid simulation and X-ray CT images for soot deposition in a diesel filter

Recently, stricter diesel particulate emission standards have been set in many countries. As for the after-treatment of exhaust gas, a diesel filter has been developed to trap diesel particles inside small-scale porous structure. Since measurement of flow in the filter is impossible, the phenomena of particle deposition in the filter are not well understood. In this study, we conducted Lattice Boltzmann simulation on flow in the newly developed diesel filter. The soot deposition was included to consider the particle trap in the filter. The inner structure of the diesel filter as well as trapped soot region was scanned by an X-ray CT technique. Results show that the flow pattern is largely changed when the soot is attached to the filter surface. By comparing simulation results with CT images, soot accumulation region is well predicted. It is found that the amount of trapped soot is proportional to the filter back-pressure even when soot deposition probability is changed.     

Total Synthesis of the Bicyclic Depsipeptide HDAC Inhibitors Spiruchostatins A and B, 5′′‐epi‐Spiruchostatin B,FK228 (FR901228) and Preliminary Evaluation of Their Biological Activity

The bicyclic depsipeptide histone deacetylase (HDAC) inhibitors spiruchostatins A and B, 5′′‐epi‐spiruchostatin B and FK228 were efficiently synthesized in a convergent and unified manner. The synthetic method involved the following crucial steps: i) a Julia–Kocienski olefination of a 1,3‐propanediol‐derived sulfone and a L ‐ or D ‐malic acid‐derived aldehyde to access the most synthetically challenging unit, (3S or 3R,4E)‐3‐hydroxy‐7‐mercaptohept‐4‐enoic acid, present in a D ‐alanine‐ or D ‐valine‐containing segment; ii) a condensation of a D ‐valine‐D ‐cysteine‐ or D ‐allo‐isoleucine‐D ‐cysteine‐containing segment with a D ‐alanine‐ or D ‐valine‐containing segment to directly assemble the corresponding seco‐acids; and iii) a macrocyclization of a seco‐acid using the Shiina method or the Mitsunobu method to construct the requisite 15‐ or 16‐membered macrolactone. The present synthesis has established the C5′′ stereochemistry of spiruchostatin B. In addition, HDAC inhibitory assay and the cell‐growth inhibition analysis of the synthesized depsipeptides determined the order of their potency and revealed some novel aspects of structure–activity relationships. It was also found that unnatural 5′′‐epi‐spiruchostatin B shows extremely high selectivity (ca. 1600‐fold) for class I HDAC1 (IC₅₀=2.4 nM ) over class II HDAC6 (IC₅₀=3900 nM ) with potent cell‐growth‐inhibitory activity at nanomolar levels of IC₅₀ values.     

A Peanut‐Shaped Polyaromatic Capsule: Solvent‐Dependent Transformation and Electronic Properties of a Non‐Contacted Fullerene Dimer

Synthesis of molecular containers capable of incorporating multiple fullerenes remains challenging. Reported here is that room‐temperature mixing of metal ions with W‐shaped bispyridine ligands featuring polyaromatic panels results in the quantitative formation of a peanut‐shaped M₂L₄ capsule. The capsule reversibly converts into two molecules of an ML₂ double tube in response to changes in the solvent. Notably, the capsule allows the incorporation of two fullerene molecules into the connected two spherical cavities at room temperature. The close proximity yet non‐contact of the encapsulated C₆₀ molecules, with a separation of 6.4 Å, was revealed by X‐ray crystallographic analysis. The resultant, unusual fullerene dimer undergoes sequential reduction within the capsule to generate (C₆₀^.?)₂, C₆₀^.??C₆₀^2?, and (C₆₀^2?)₂ species. Furthermore, temperature‐controlled stepwise incorporation of two C₆₀ molecules into the capsule is demonstrated.     

Mechanistic studies of hydrogen-peroxide-mediated anthocyanin oxidation

The oxidation of cyanidin-3-O-glucoside by hydrogen peroxide was investigated in a range of solvents. The reaction products had chemical structures identical to those formed by the reaction of this compound with the alkylperoxyl radical 2,2?-azobis(2,4-dimethyl)valeronitrile. A plausible oxidation mechanism was proposed based on the obtained reaction products, and this mechanism was confirmed by HPLC–MS experiments using ¹⁸O-labeled reagents. Further, the reaction conditions were found to influence both the reaction rate and the products formed during the transformation, which validated the proposed mechanism.     

Restructuring of the bleomycin metal core. Novel oxygen-activating ligands with symmetrized structure

Novel ligands having symmetrized coordination environment consisting of two histidine units and a pyridine are prepared. Oxygen activating efficiency of the iron complexes of the synthetic ligands increases by introducing electron donating substituent into the pyridine ring.     

Characteristics of proflavine solubilized in complexes of anionic polymers with a cationic surfactant

Absorption and emission spectra of 3,6-diaminoacridine (proflavine) are reported in mixed solutions of dodecyltrimethylammonium bromide (DTAB) with various polyelectrolytes including the sodium salts of poly(acrylic acid) (PAA). poly(methacrylic acid) (PMA), poly(styrenesulfonic acid) (PSS), poly(garacturonic acid) (pectate), and the alternating copolymers of maleic acid with ethylene (PMA-E) and styrene (PMA-S). The spectral change indicates the association of the dye (blue-shift) on these polyions except on PSS, the easy dissociation of the aggregated form into the monomeric form and the solubilization into the hydrophobic PMA-S/DTAB complex (red-shift), the little dissociation in the PAA/DTAB, PMA/DTAB and PMA-E/DTAB complexes, and the liberation of the bound dye in the case of pectate/DTAB complexes. In the PSS system, the strong interaction of the dye with the styrene groups induces the completely different spectral behavior. These results are discussed with the cooperative binding of the dye and the surfactant ion.     

Trifluoroethylxanthate as an analytical reagent: Spectrophotometric determination of cobalt and copper as their trifluoroethylxanthates

Summary A direct spectrophotometric method has been developed for the micro-determination of Co(II) and Cu(II) as their trifluoroethylxanthates, by use of aqueous acetone medium. The reagent and methods have been found selective and sensitive for the determination of these metals in certain alloys.

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Trifluorethylxanthat als analytisches Reagens: Spektrophotometrische Bestimmung von Kobalt und Kupfer

Zusammenfassung Eine direkte spektrofluorimetrische Methode zur Mikrobestimmung von Co(II) und Cu(II) in Form ihrer Trifluorethylxanthate in wäßrigem Acetonmedium wurde ausgearbeitet. Reagens und Methode sind bei der Bestimmung der genannten Metalle in gewissen Legierungen selektiv und empfindlich.