Separation and purification of 99mTc from 99Mo produced by electron linear accelerator

The medical radionuclide ⁹⁹Mo was produced by the ¹⁰⁰Mo(γ,n) reaction using bremsstrahlung photons generated by an electron linear accelerator. The amount of ⁹⁹Mo produced was compared to that predicted by calculation using the particles and heavy ion transport code system. From the ⁹⁹Mo produced, highly pure ^99mTc was separated using the so-called technetium master milker, and the chemical yield of ^99mTc was 83–99 %. The installation of a new complex using this method and the electron linear accelerator with the preferable specification was suggested, and a possibility to supply the demand of ^99mTc was discussed and shown.

     

Determination of gallium by graphite furnace atomic absorption spectrometry with combined use of a tungsten-coated L'vov platform tube and a chemical modification technique

Tungsten-coated non-pyrolytic graphite (NPG), pyrolytic graphite (PG) and pyrolytic L'vov platform graphite (PPG) tubes were prepared, and their analytical performances were compared. The coating process simply involved injecting 100 μl of a sodium tungstate solution (0.01 mol l⁻¹) into each graphite tube, followed by heating according to a temperature programme similar to an atomisation cycle for the determination of gallium. This procedure for coating was repeated at least 12, 25, and 7 times towards NPG, PG, and PPG tubes, respectively. Among these tubes, the tungsten-coated PPG tube showed excellent performance for the determination of gallium. By combined use of a chemical modifier such as aluminium(III) or nickel(II) a detection limit (3σ) of 6 pg and sensitivity (1% absorption) of 3–4 pg were achieved. The practical potential of the proposed technique was demonstrated for the determination of gallium in several samples of alloys and fresh water.     

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)(n)() (n = 2 or 3)

A novel class of catalysts for alkane oxidation with molecular oxygen was examined. N-Hydroxyphthalimide (NHPI) combined with Co(acac)(n)() (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions. Cycloalkanes were successfully oxidized with molecular oxygen in the presence of a catalytic amount of NHPI and Co(acac)(2) in acetic acid at 100 degrees C to give the corresponding cycloalkanones and dicarboxylic acids. Alkylbenzenes were also oxidized with dioxygen using this catalytic system. For example, toluene was converted into benzoic acid in excellent yield under these conditions. Ethyl- and butylbenzenes were selectively oxidized at their alpha-positions to form the corresponding ketones, acetophenone, and 1-phenyl-1-butanone, respectively, in good yields. A key intermediate in this oxidation is believed to be the phthalimide N-oxyl radical generated from NHPI and molecular oxygen using a Co(II) species. The isotope effect (k(H)/k(D)) in the oxidation of ethylbenzene and ethylbenzene-d(10) with dioxygen using NHPI/Co(acac)(2) was 3.8.     

Ultraweak Luminescence Generated by Sweet Potato and Fusarium oxysporum Interactions Associated with a Defense Response

Abstract— Ultraweak luminescence generated by sweet potato and nonpathogenic Fusarium oxysporum interactions associated with a defense response was detected by a photoncounting method using ultrahigh-sensitive photodetectors. The time-dependent intensity variation, the spectrum and the two-dimensional imaging of the ultraweak luminescence are indicative of the defense response of the sweet potato to F. oxysporum. The production of ipomeamarone as a phytoalexin means that F. oxysporum induced the defense response in the sweet potato.     

Stepwise annealing of poly(butylene terephthalate)

Annealing of poly(butylene terephthalate) (PBT) was studied by differential scanning calorimetry (DSC) and small angle X‐ray scattering (SAXS) measurement. A PBT sample was annealed at a recrystallization temperature where recrystallization occurs with a maximum rate in the heating process of the sample. In the subsequent annealing steps, the annealed sample was annealed repeatedly at the recrystallization temperatures, and the stepwise annealing sample was obtained. Peak melting temperature (T_m) and sharpness of DSC peak of the stepwise annealing sample increased with the annealing step. A high melting‐temperature sample was obtained in a short time, and T_m increased up to 238.5°C which is higher than all the T_m values that appear in the literature. The long period calculated from SAXS curves of the stepwise annealing sample increased with the annealing step. The increase of crystallite size and perfection of the crystal in the stepwise annealing process is suggested. Annealing experiment indicated that T^°_m should be higher than about 235°C. T_m increased linearly with the annealing temperature of the final step in the stepwise annealing (T_a). The equilibrium melting temperature (T^°_m) for PBT was estimated to be 247°C by the application of a Hoffman–Weeks plot to the relation between T_m vs. T_a. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2420–2429, 1999     

Molecular hybrids of azobenzene polymer and liquid crystal molecule. A new approach for understanding the command surface system

Langmuir-Blodgett (LB) films consisting of the hybrid of a polymer having the azobenzene (Az) side chain and 4î-pentyl-4-cyanobiphenyl (5CB) are prepared. Microscopic observations and spectroscopic data both indicate that the Az side chain and 5CB are homogeneously mixed at a molecular level without phase separation in the layer. This provides a satisfactory model of the command surface system. Time course accumulation of spectroscopic data for multilayered hybrid films reveals the cooperative nature of the photo-motivated molecular motions.     

Crystalline‐Sponge‐Based Structural Analysis of Crude Natural Product Extracts

Characterization of complex natural product mixtures to the absolute structural level of their components often requires significant amounts of starting materials and lengthy purification process, followed by arduous structure elucidation efforts. The crystalline sponge (CS) method has demonstrated utility in the absolute structure elucidation of isolated organic compounds at miniscule quantities compared to conventional methods. In this work, we developed a new CS‐based workflow that greatly expedites the in‐depth structural analysis of crude natural product extracts. Using a crude extract of the red alga Laurencia pacifica, we showed that CS affinity screening prior to compound isolation enables prioritization of analytes present in the extract, and we subsequently resolved the molecular structures of six sesquiterpenes with stereochemical clarity from around 10 mg crude extract. This study demonstrates a new chemotyping workflow that can greatly accelerate natural product discovery from complex samples.     

Synthesis of dendritic bisphosphonates as bone targeting ligands

A dendritic bisphosphonate carrying three bisphosphonate (BP) units in close proximity was designed as a ligand to conjugate large therapeutic molecules for their bone selective delivery. The Bu₃P-catalyzed conjugate addition of nitromethane to vinylidene bisphosphonate was effective to construct a quaternary carbon center carrying BP units. Owing to multivalent interactions, the dendritic bisphosphonate showed considerable affinity for the bone mineral hydroxyapatite even in the presence of a competitor, demonstrating potential as a bone targeting ligand.     

Preparation and characterization of novel polyaryloxydiphenylsilanes with high glass transition temperature by melt polycondensation of dianilinodiphenylsilane with bisphenols

Novel polyaryloxydiphenylsilanes with reduced viscosities of 0.31–0.65 dL/g were obtained by the melt polycondensation of dianilinodiphenylsilane with three bisphenols, 2,2-bis (4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, 3 (4-hydroxyphenyl)-1,1,3-trimethyl-5-indanol, and 9,9-bis (4-hydroxyphenyl) fluorene, at 200–320°C in vacuo. These polymers are all amorphous and readily soluble in a wide variety of organic solvents such as chlorinated and aromatic hydrocarbons, cyclic ethers, and polar aprotic solvents. Because of their bulky and/or rigid ring structures, polyaryloxydiphenylsilanes containing diphenylhexafluoropropane, phenylindane, and diphenylfluorene units in the main chain have high glass transition temperatures of 106, 112, and 172°C, respectively. They are thermally stable showing almost no weight loss up to 350°C in air. Colorless, transparent, but brittle films are obtained from these polymers by solution casting. Ultraviolet transmission is sharply cut off by these polyaryloxydiphenylsilane films at ca. 300 nm, and the cut-off wavelength depends on the bisphenols used.