Depth estimation of protoporphyrin IX objects in turbid media considering the fluorescence intensity ratio between two wavelengths of light for application in invasion diagnosis of gastric cancer

Optical Review - This paper demonstrates a method to estimate the depth of a fluorescence object in turbid media using dual-wavelength excited photodynamic diagnosis, to aid in the invasion depth...     

PEO-based composite lithium polymer electrolyte, PEO-BaTiO3-Li(C2F5SO2)2N

Polyethylene oxide (PEO) based polymer electrolytes with BaTiO₃ as filler and Li(C₂F₅SO₂)₂N as salt have been examined in lithium polymer batteries. The aluminum disolution potential in PEO-Li(C₂F₅SO₂)₂N was estimated to be 4.1 V vs. Li/Li⁺ at 80 °C, which was compared to that of 3.8 V vs. Li/Li⁺ in PEO-Li(CF₃SO₂)₂N. The electrical conductivity of the system was measured as a function of O/Li ratio. The highest conductivity was observed in O/Li=8. The conductivity was 1.65×10⁻³ S/cm at 80 °C and 1.5×10⁻⁵ S/cm at 25 °C. The interfacial resistance of Li/polymer electrolyte/Li annealed at 80 °C for 15 days was lower than 100 Ωcm². Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16 – 22, 2001.     

Novel method to control release of lipophilic drugs with high potency from silicone

Silicone has been utilized as a carrier material for sustained release system of lipophilic drugs. Extensive studies revealed that drug release rate is influenced by factors such as physicochemical properties of the drug and additives.(1-5)) When a lipophilic drug is highly potent at low concentrations, the drug release rate should be strictly controlled so as to avoid side effects. In this study, using vitamin D(3) (VD(3)) as an example of such drugs, we investigated novel method to suppress initial burst and to modify drug release rate from silicone matrix. As a result, it was found that (a). addition of human serum albumin (HSA) suppressed initial burst and enhanced release rate in the later stage, resulting constant release of VD(3), (b). covering a matrix formulation with a membrane of low diffusivity (core-rod formulation) suppressed initial burst and released drug in a constant rate, and (3) using materials for which the drug has high affinity as dissolution solvent (reservoir formulation), the drug release rate was reduced.     

Large-scale separation of metallic and semiconducting single-walled carbon nanotubes

In the applications of single-walled carbon nanotubes (SWNTs), it is extremely important to separate semiconducting and metallic SWNTs. Although several methods have been reported for the separation, only low yields have been achieved at great expense. We show a separation method involving a dispersion-centrifugation process in a tetrahydrofuran solution of amine, which makes metallic SWNTs highly concentrated to 87% in a simple way.     

1,6-dihydro-3(2H)-pyridinones as synthetic intermediates. Total synthesis of (±)-tecomanine

The first and stereoselective total synthesis of (±)-tecomanine ($\text{1}$) has been achieved from ethyl 1,6-dihydro-3(2H)-pyridinone-1-carboxylate ($\text{2}$) as a synthon.     

Photochemical valence tautomerization of berberinephenolbetaines to 8,14-cycloberbines,versatile aziridine derivatives for spirobenzylisoquinolines

Irradiation of the berberinephenolbetaines ($\text{8}$$\text{a}$, $\text{8}$$\text{b}$, and $\text{8}$$\text{c}$) effected valence tautomerization to give the 8,14-cycloberbines ($\text{9}$$\text{a}$, $\text{9}$$\text{b}$, and $\text{9}$$\text{c}$), the aziridine derivatives, in high yield. The 8,14-cycloberbines were efficiently converted to the spirobenzylisoquinolines by regioselective C bond cleavage.     

Synthesis of Vinyl Polymer—Poly (α-Amino Acid) Block Copolymers by End-Reactive Oligomers

In order to synthesize block copolymers consisting of segments having dissimilar properties, vinyl polymer - poly (α-amino acid) block copolymers were synthesized by two different methods. In the first method, the terminal amino groups of polysarcosine, poly(γ-benzyl L-glutamate), and poly(γ-benzyloxycarbonyl-L-lysine) were haloacetylated. The mixture of the terminally haloacetylated poly (α-amino acid) and styrene or methyl methacrylate was photoirradiated in the presence of Mo (CO)₆ or heated with Mo(CO)₆, yielding A-B-A-type block copolymers consisting of poly(α-amino cid) (the A component) and vinyl polymer(the B component). The characterization of block copolymers revealed that the thermally initiated polymerization of vinyl compounds by the trichloroacetyl poly(α-amino acid)/Mo(CO)₆ system was most suitable for the synthesis of vinyl polymer - poly-(α-amino acid) block copolymers. In the second method, poly (methyl methacrylate) and polystyrene having a terminal amino group were synthesized by the radical polymerization in the presence of 2-mercaptoethylammonium chloride. Using these polymers having a terminal amino group as an initiator, the block polymerizations of γ-benzyl L-glutamate NCA and e-benzyloxycarbonyl-L-lysine NCA were carried out, yielding A-B-type block copolymer. By eliminating the protecting groups of the side chains of poly(α-amino acid) segment, block copolymers such as poly(methyl methacrylate) with poly(L-glutamic acid) or poly(L-lysine) and polystyrene with poly(L-glutamic acid) and poly(L-lysine) were successfully synthesized.     

Efficient partial hydrogenation of trichloromethyl to gem-dichloromethyl groups in platinum on carbon-catalyzed system

While gem-dichloromethyl groups can be directly synthesized by the mono-dechlorination of the corresponding trichloromethyl groups, the suppression control of the over-reduction to form chloromethyl or methyl functionalities is quite difficult. We have established the efficient and widely applicable mono-dechlorination method of the trichloromethyl groups to form the corresponding gem-dichloromethyl groups using platinum on carbon in dimethylacetamide as a specific solvent at 25 °C under a hydrogen atmosphere. The mono-dechlorination of the α,α,α-trichloromethylcarbonyl groups smoothly proceeded by the use of platinum on carbon as a catalyst in a highly chemoselective manner, while the efficient mono-dechlorination of the alkyl- and aryl-trichloromethyl groups required the combined use of Bu₃SnH.