Observation and evaluation of proton diffusion in porous media by the pH-imaging microscope using a flat semiconductor pH sensor.

The diffusion of protons in porous media was observed and evaluated using a pH-imaging microscope with a flat semiconductor. Small particles were packed on the sensing surface of the flat sensor, followed by the addition of a lactic acid droplet on the top of the packed particle layer. The pH distribution accompanied by the diffusion of lactic acid was visualized at the bottom of the layer using the flat sensor. The difference in the diffusion property was confirmed depending on the particle type. The effective diffusion coefficients of the lactic acid in some porous media were estimated by combining the experimental results and mathematical calculation.     

Efficient optical near-field energy transfer along an Au nanodot coupler with size-dependent resonance

We confirmed that the light intensity (λ=785 nm) scattered from an isolated hemispherical Au nanoparticle was resonantly enhanced at a diameter of 200 nm and a height of 50 nm, as observed experimentally using a collection-mode near-field optical microscope. The experimental results agreed with the calculated results using Mie’s theory. Furthermore, we observed resonant energy transfer of the optical near-field energy along a chain of Au nanoparticles. The magnitude of the transferred energy increased resonantly at the size of resonant light scattering for an isolated Au nanoparticle (200 nm diameter with 240 nm center-to-center separation). PACS 42.82.Et; 73.20.Mf; 78.67.Bf     

Preparation of a cycloheptane ring from a 1,2-diketone with high stereoselectivity

Treatment of 1,6-dialkylhexa-1,5-diene-3,4-diones with bis(iodozincio)methane gave zinc alkoxides of cis-5,6-dialkylcyclohepta-3,7-diene-1,3-diol in good yields at room temperature. The reaction proceeded with high stereospecificity. Bis(iodozincio)methane converted the diketone into the cis-divinylcyclopropane-1,2-diol stereoselectively; this diol transformed into the corresponding cycloheptane derivative stereospecifically via Cope rearrangement.     

Sulfur-rich CpCo(dithiolene) complexes: Isostructural or non-isostructural couples of CpCo(III) with CpNi(III) dithiolene complexes

Eight new sulfur-rich [CpCo(dithiolene)] complexes were synthesized from [Zn(dmit)₂]²⁻ as a starting material. The structures, electrochemical behavior and electronic absorption spectra of the sulfur-rich [CpCo(S₂C₂S₂Y)] complexes could be compared with the early data of analogous Ni complexes. [CpCo(pddt)] (Y = -(CH₂)₃-), [CpCo(dpdt)] (Y = -CH₂C(CH₂)CH₂-), [CpCo(bddt)] (Y = -(CH₂)₄-), [CpCo(dtdt)] (Y = -CH₂SCH₂-) and [CpCo(poddt)] (Y = -CH₂C(O)CH₂-) crystallized in all isostructural with the corresponding paramagnetic [CpNi(dithiolene)] complexes, but [CpCo(dmid)] (Y = CO), [CpCo(dddt)] (Y = -(CH₂)₂-) and [CpCo(F₂pddt)] (Y = -CH₂CF₂CH₂-) crystallized in non-isostructural with them. These molecules are associated with intermolecular short S?S contacts in the crystals. [CpCo(F₂pddt)] did not show any remarkable S?S contacts but indicated interesting fluorine segregation and Cp?Cp face-to-face interactions. Redox potentials of [CpCo(dithiolene)] complexes were obtained with the cyclic voltammetry measurements and dimerized by electrochemical oxidations. Electronic absorption spectra of [CpCo(dithiolene)] complexes showed visible absorption in the range of 585-701 nm as lowest energy wavelengths (? = 9800-11,800 M⁻¹ cm⁻¹) in solutions, and they were higher energy than those of [CpNi(dithiolene)] complexes (near-IR).     

CO2 absorption of perovskites as seen by positron lifetime spectroscopy

The CO₂ absorption of several ABO₃ type perovskites was studied by positron lifetime spectroscopy. The longer positron lifetime was associated with positrons trapped by A site vacancies. The evaluated positron lifetime data indicated the relative stability of the crystal structure of Sr(Co_0.5Fe_0.5)O_3−δ against Ca doping at low Ca concentrations. Oxygen desorption and CO₂ absorption/desorption could also be followed by positron lifetime spectroscopy. It was shown that the concentration of oxygen vacancies has a large effect on positron lifetime data through the electron density of A site vacancies.     

Polyion complex stabilized palladium nanoparticles for Suzuki and Heck reaction in water

Palladium nanoparticles stabilized by a polyion complex composed of poly{4-chloromethylstyrene-co-(4-vinylbenzyl) tributylammonium chloride} and poly(acrylic acid) were easily recovered by filtration after pH treatment. The polyion complex stabilized palladium nanoparticles have high catalytic activity for the Suzuki and Heck reactions in water.     

On embedding problems with restricted ramifications

Archiv der Mathematik - Let L / k be a Galois extension with Galois group G, and $(\varepsilon ): 1\to A\to E\to G\to 1$ a central extension. We study the existence of the Galois extension M / L /...     

Direct evidence for degradation of esperamicin A1 with thiol confirmed by fast-atom bombardment mass spectrometry.

A degradation of esperamicin A1, which is a potent antitumor antibiotic having DNA-cleaving activity, was studied by fast-atom bombardment (FAB) mass spectrometry. It was proved that the degradation easily occurs via the thiol group(s) in the matrix solution and not by a FAB-induced reaction. It was concluded that from the FAB mass spectra of all non-volatile compounds, the molecular weight should be determined by using at least two chemically different matrices.     

Immobilization of RuS2 Nanoparticles Prepared in Reverse Micellar System onto Thiol-Modified Polystyrene Particles and their Photocatalytic Properties

RuS₂ nanoparticles, smaller than 3 nm in diameter, were prepared by H₂S gas injection into the AOT/isooctane reverse micellar solution containing RuCl₃ aqueous solution. The nanoparticle size was found to be independent of the W_o (water content) value of the reverse micellar system, as shown by TEM observation. The recovery and immobilization of the RuS₂ nanoparticles from reverse micelles onto thiol-modified polystyrene particles (PSt-SH) were successfully carried out, by the addition of PSt-SH into the reverse micellar solution under conditions of mild stirring. The resulting composites, PSt-RuS₂, showed photocatalytic activity for H₂ generation form aqueous solution containing 2-propanol and Na₂SO₃ as sacrificial electron donors.     

Synthesis and structure-activity relationships of substituted 2-[(2-imidazolylsulfinyl)methyl]anilines as a new class of gastric H+/K(+)-ATPase inhibitors. II.

A series of 2-[(2-imidazolylsulfinyl)methyl]anilines (2) having various substituents on their imidazole and aniline rings was synthesized and examined for their H+/K(+)-ATPase (adenosine triphosphatase) inhibitory effects and antisecretory activity against histamine-stimulated gastric acid secretions in Heidenhain pouch dogs. Although substitutions on the imidazole ring did not enhance biological activity, substitutions on the aniline ring by electron-donating substituents potently enhanced the enzyme inhibitory activity and also showed an inhibitory effect on histamine-stimulated gastric acid secretion after oral administration. In particular, the in vitro activity of the dimethyl (2u--w) and trimethyl (2ac) derivatives was about 10 times that of omeprazole. Also, 4-methyl (2k), 4-methoxy-5-methyl (2y) and 3,5-dimethyl-4-methoxy (2ab) derivatives showed a potent antisecretory effect of more than 80% after oral administration at 6 mg/kg. Although these aniline derivatives have relatively low stabilities in aqueous solution, replacement of the isobutyl group at the aniline nitrogen atom with N-(2-methoxyethyl) group enhanced the stability.