A new synthetic route to oligoribonucleotides based on CpRu-catalyzed deallylation

A triribonucleotide 3-5 U, which is fully protected by an allyl group at the 2′-hydroxy and phosphoric acid positions was synthesized, the deprotection being quantitatively achieved by use of a catalytic amount of CpRu(η³-C₃H₅)(2-quinolinecarboxylato) in methanol. The reaction is completed within 30 min at ambient temperature. The utility of the simple allyl protecting group has the potential to open a new pathway in the synthesis of RNA-related compounds.     

Design of unique titanium oxide photocatalysts by an advanced metal ion-implantation method and photocatalytic reactions under visible light irradiation

The metal ion-implantation of titanium oxide with various transition metal ions was carried out by applying by high voltage acceleration. The subsequent calcination of the implanted TiO₂ in oxygen at around 723 K resulted in a large shift in the absorption spectra of the TiO₂ toward visible light regions, its extent being dependent on the amount and the kind of metal ions implanted. Such metal ion-implanted titanium oxide catalysts were active in carrying out various photocatalytic reactions such as the decomposition of NO into N₂, O₂ and N₂O at 275 K under irradiation with visible light longer than 450 nm. The application of this advanced, high energy metal ion-implantation method enables the novel design of titanium oxide photocatalysts which can absorb and initiate vital reactions under visible light and will contribute to the development of catalytic systems utilizing solar energy.     

Zeta Regularizations

We survey our work on various generalizations of the usual zeta regularized product and their applications. For construction of functions having a certain invariance and a given set of zeros, so-called the zeta regularization method is quite useful. We exhibit several examples and discuss some questions.     

Simple formylacetal (CH2) as a novel linker for saccharide synthesis on soluble-polymer support

Described herein is a new formylacetal (CH₂) linker for immobilization of small molecules onto a soluble-polymer support, poly(ethylene glycol) ω-monomethyl ether (MPEG), and its application to saccharide synthesis. This small linker allows immobilization of a hindered hydroxy group such as the 4-hydroxy group of glucose onto MPEG. The linker is stable under several reaction conditions including glycosylation. Removal of this support was found to be achieved through cleavage of the CH₂ linker either by a Lewis acid (TMSI or Ce(OTf)_x) or a Brønsted acid (trifluoroacetic acid) in moderate to good yields. In combination with solid acid catalyst, simpler operations became possible during the working-up and purification processes.     

The Role of Current Density and Applied Voltage During Anodization for Porous Silicon

Porous silicon is usually formed by means of the anodization under constant current density. In order to study the role of the applied voltage during the anodization, we formed porous silicon on condition that the applied voltage was constant. The current density was not always large when the applied voltage was large. We have found that the thickness of the formed porous layer correlated with the current density while photoluminescent intensity depended on the applied voltage. When the anodization was performed with a comparatively large current density, the constant-voltage condition caused unstable current density accompanied by partial peeling of the surface.     

Experimental studies of the radiative properties of sulfur dioxide

The narrow band-model parameters S/d, γ_N/d and B have been obtained experimentally for the infrared bands of SO₂. Good agreement was obtained between the present experimental and previous theoretical studies. The revised wide band-model parameters were determined and used to calculate total gas emissivities, which are found to be considerably different from previously published values.     

Automatic sensitivity analysis of kinetic mechanisms

An algorithm for the automatic sensitivity analysis of kinetic mechanisms based on the Fourier amplitude sensitivity test (FAST) method of Shuler and co-workers is reported. The algorithm computes a measure of the relative sensitivity of each concentration to each parameter of interest, such as rate constants, Arrhenius parameters, stoichiometric coefficients, and initial concentrations. Arbitrary variations in the magnitude of the parameters are allowable. The algorithm is illustrated for the simple example of computing the sensitivity of the concentration of species A to variation of the two Arrhenius parameters for the hypothetical reaction A + A →.     

System for precise measurement in inverse Raman spectroscopy

A system for precise measurement was developed for inverse Raman spectroscopy, using a cw argon laser and a pulsed dye laser pumped by a YAG laser. The frequency accuracy was assured by monitoring the frequency of both of the lasers with an iodine fluorescence cell or a Fabry-Perot etalon dynamically calibrated by a stabilized HeNe laser. The spectrometer system employed a digitally controlled mechanism to handle the complicated measurement procedure and hence to reduce the overall measurement time. The performance of the system was tested by measuring the CH₄ v₁ lines and the H₂ Q(1) line.