Analysis of dielectric observations of KCl-charged poly(methyl methacrylate) microcapsules using a two-component model consisting of KCl-permeable and KCl-impermeable capsules

Dielectric measurements were carried out on aqueous suspensions of poly(methyl methacrylate) microcapsules charged with KCl solutions to examine the KCl permeability of the microcapsules. The specimens exhibited three kinds of dielectric relaxation. Two kinds of dielectric relaxation were observed immediately after washing the specimens with distilled water. These overlapped each other when the specimen was left standing in the measuring cell for a long time. Their relaxation frequencies were affected by the KCl concentration of the suspending medium in which the specimen was kept before washing. Another relaxation was observed distinctly when the spepcimens were washed thoroughly with distilled water. Its relaxation frequency was affected by the KCl concentration of the charged solution. These results were explained by assuming that the specimens were mixtures of KCl-permeable and KCl-impermeable capsules. The theoretical analysis procedure was devised in the light of dielectric theory of interfacial polarization to estimate the parameters which characterize the structure of the specimens.     

Specific radiation and recoil energy effects in recoil implantation reaction of51Cr in metal acetylacetonates

In recoil implantation reaction of⁵¹Cr in Cr/acac/₃ a polymer component which was sensitive to radiation dose was found. However, a retention type component⁵¹Cr/acac/₃ was not so sensitive to radiation dose. A remarkable dependence of the yield of⁵¹Cr/acac/₃ on recoil energy was found in the range 10²–10⁶ eV in recoil implantation using a thin film technique. This suggests a special role of implantation reaction in solids.     

Dependence of the Reactivities of Titanium Enolates on How They Are Generated: Diastereoselective Coupling of Phenylacetic Acid Esters Using Titanium Tetrachloride

Oxidative coupling of phenylacetic acid esters was easily achieved by treating the esters with TiCl(4) and then adding Et(3)N to the resulting solution. The products consisted of dl- and meso-2,3-diphenylsuccinic acid esters with the Claisen condensation product, and the ratio of these products depended on the reaction conditions. Reaction conditions suitable for high dl selectivity were determined, and a dimer of titanium enolate was postulated as an intermediate responsible for the high dl selectivity. The selectivities were compared with those in known oxidative couplings in which titanium enolate intermediates are prepared through lithium enolates and silyl enol ethers. The results suggest that the reactivities of titanium enolates intermediates depend on how they are generated.     

Structural assignment of n3-acylated uridine derivatives by means of 13c nmr spectroscopy

Diisopropylethylamine was effective as a base for acylation of 2′,3′,5′-tri-O-acetyluridine with various acid chlorides. The ¹³C NMR spectra of the products and related compounds showed clearly that the acyl groups intoduced to the uracil moiety are attached to the N³-nitrogen.     

A new convenient method for the synthesis of mixed-ligand β-diketonato Tc(III) complexes

A new convenient method has been proposed to synthesize mixed-ligand -diketonato Tc(III) complexes, using the ligand exchange reaction [Tc(acac)₂(CH₃CN)₂]⁺+L^–[Tc(acac)₂L]+ +2CH₃CN where L is bza, dpm or dbm. The yield was about 30–40%. UV-visible and IR spectra of these complexes were measured. Characteristic features of the compounds were compared with those of the corresponding complexes of ruthenium.     

Conversion of endohedral <Superscript>133</Superscript>Xe-fullerene to endohedral <Superscript>133</Superscript>Xe-fullerenol to be used in nuclear medicine

Summary Hydrophilic endohedral ¹³³Xe-fullerenols, [¹³³Xe@C₆₀(OH)_xand ¹³³Xe@C₇₀(OH)_x], were synthesized from hydrophobic endohedral ¹³³Xe-fullerenes. The yield of endohedral ¹³³Xe-fullerenols extracted in water was about 40% and 23% for C₆₀and C₇₀, respectively. The products stored in 0.9% NaCl solution at 20 °C were stable enough to be used in nuclear medicine.     

Thermal degradation of poly[(tetramethyl-p-silphenylene) siloxane]

For the purpose of studying the mechanism of thermal degradation of poly[(tetramethyl-p-silphenylene) Siloxane] (poly TMPS) a series of polymers with silphenylene and siloxane bonds in the main chain were prepared and subjected to thermogravimetry (TG) and pyrolysis study. Analyses of products from poly TMPS degradation (in vacuum at a constant temperature) by gas chromatography (GC), infrared (IR), nuclear magnetic resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry (GC–MS) revealed that degradation occurs at the silphenylene bonds. The TG curves obtained in He for heating rates of 1,2,2.5,7.5, and 10°C/min were analyzed by the Ozawa method; activation energies of 39 ± 1 and 45 ± 2 kcal/mol were obtained respectively for the initial cleavage of the methyl side group and the later-stage scission of the main-chain silphenylene bond which leads to a major weight loss. The results agree with those obtained for other structurally similar polymers.     

New guanosine derivatives: facile O6-phosphorylation,thiophosphinylation sulfonylation and silylation of guanosine derivatives by 4-dimethylaminopyridine catalized reaction

Appropriately protected guanosine derivatives were successfully converted to the corresponding O⁶-substituted guanosine derivatives by treatment with dialkyl- or diaryl-phosphoryl halides, dialkyl- or diaryl-phosphinothioyl halides, arenesulfonyl chlorides, and trialkylsilyl chlorides.     

Systematic high-pressure synthesis of new filled skutterudites with heavy lanthanide, LnFe4P12 (Ln=heavy lanthanide, including Y)

New filled skutterudites with heavy lanthanide, LnFe₄P₁₂ (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) have systematically been prepared for the first time by the high-pressure technique. The relationship between lattice constants and atomic numbers of lanthanide (including Y) is established for LnFe₄P₁₂. Electrical and magnetic properties of several new filled skutterudites with heavy lanthanide have been studied at low temperatures; YFe₄P₁₂ shows a superconducting transition at around 7 K, and DyFe₄P₁₂ behaves as a ferromagnet below 10 K. Electrical and magnetic anomalies in DyFe₄P₁₂ and YFe₄P₁₂ are mainly discussed.     

Solvent extraction of metal ions with mixed ligands: Extraction and separation of calcium and strontium with TTA and TBP in carbon tetrachloride

The solvent extraction of calcium(II) and strontium(II) by TTA has been studied using carbon tcetrachloride containing trioctylphosphine oxide (TOPO), tributylphosphate (TBP), and methyl isobutyl ketone (hexone) as adduct-forming ligands. Stability constants for the systems are given. The separation of calcium and strontium can be effected by 0.1 M TTA +0.01 M TBP in carbon tetrachloride.