Evaluation of the radioactivity in concrete from accelerator facilities

For evaluation of radioactivity induced in the concrete samples from accelerator facilities, the residual radioactivity in concrete sample, collected from seven accelerator facilities, was determined by γ-ray spectrometry. The tritium was extracted by the heating method using an IR furnace, and measured with a liquid scintillation counter. It was found that the major radioisotopes activated mainly by neutrons in the concrete samples were ¹⁵²Eu, ⁶⁰Co, ¹³⁴Cs and ³H. The concentrations of radioactivities induced by thermal neutron capture are the highest at a depth of 10 cm in the concrete wall. The correlation between tritium, ⁶⁰Co and ¹⁵²Eu activity was investigated by measuring many concrete samples for seven accelerator facilities. The results indicate that their activities are strongly correlated with each other. So it would also be concluded that the total activity in shielding concrete could be estimated on the basis of the activities of ⁶⁰Co and ¹⁵²Eu.     

Concise and highly stereocontrolled synthesis of 1-deoxygalactonojirimycin and its congeners using dioxanylpiperidene,a promising chiral building block

[reaction: see text] A concise and stereoselective synthesis of the chiral building block, dioxanylpiperidene 4 as a precursor for deoxyazasugars, starting from the Garner aldehyde 5 using catalytic ring-closing metathesis (RCM) for the construction of the piperidine ring is described. The asymmetric synthesis of 1-deoxygalactonojirimycin and its congeners 1-3 was carried out via the use of 4 in a highly stereocontrolled mode.     

Regioselective oxidation of internal olefins bearing neighboring oxygen functions by means of palladium catalysts. Preparation of β-alkoxy or acetoxy ketones from allyl and homoallyl ethers or esters

A new preparative method of β- and γ-alkoxy (acetoxy) ketones, which are important precursors of vinyl ketones and 1,4-diketones, respectively, is presented. With PdCl₂/CuCl/O₂ or PdCl₂/p-benzoquinone catalyst system, internal olefins bearing allylic alkoxy or acetoxy group underwent regioselective oxidation to form the corresponding β-alkoxy or β-acetoxy ketones. Similarly, γ-acetoxy ketones were obtained from homoallyl acetates having internal olefins with high regioselectivity.     

Di(triptycyl)carbene: a fairly persistent triplet dialkylcarbene

The title carbene was generated and characterized by matrix spectroscopy (ESR and UV/vis) and laser flash photolysis along with theoretical calculations, which revealed interesting effects of triptycyl groups on structure and reactivities of carbenes.     

Synthesis and properties of novel fluoroalkyl end‐capped oligomers having adamantane units in the main chains via a radical process

Fluoroalkanoyl peroxides were reacted with adamantane in the presence of radical polymerizable monomers such as acrylic acid, acryloylmorpholine, and N,N‐dimethylacrylamide to afford fluoroalkyl end‐capped oligomers having adamantane units in the main chains via a radical process under very mild conditions. Thermal stability of these new fluorinated adamantane co‐oligomers thus obtained became higher than that of the corresponding fluorinated homo‐oligomers having no adamantane units. Interestingly, these fluorinated adamantane co‐oligomers exhibited good solubility in traditional organic solvents such as methanol, ethanol, tetrahydrofuran, chloroform, benzene, dimethylsulfoxide and N,N‐dimethylformamide including water, although the parent adamantane exhibited no solubility in water, methanol and dimethylsulfoxide. Furthermore, these adamantane co‐oligomers were able to reduce the surface tension effectively to form the nanometer size‐controlled self‐assembled fluorinated molecular aggregates. Copyright © 2005 John Wiley & Sons, Ltd.     

A comparison of the adsorption of saliva proteins and some typical proteins onto the surface of hydroxyapatite

Adsorption of protein from saliva on hydroxyapatite was compared with adsorption of several typical proteins with different electric charges, i.e. lysozyme, human serum albumin, β-lactoglobulin and ovalbumin. Adsorbed amounts of these proteins were determined and electrophoretic mobilities of protein-covered hydroxyapatite particles were measured, at different values for the adsorbed mass and, therefore, at various degrees of surface coverage. Also, adsorption kinetics were investigated by streaming potential measurements of a hydroxyapatite surface in contact with a protein solution, allowing monitoring of changes in the zeta-potential of the protein-covered hydroxyapatite surface in real time. The adsorbed amounts show that, as compared to most of the other proteins, the saliva proteins have remarkably low adsorption affinity. The measured values for the electrophoretic mobilities indicate that the positively charged proteins in the saliva mixture preferentially adsorb onto the negatively charged hydroxyapatite surface; this is most pronounced at low protein concentration in solution (i.e. at low coverage of the surface by the protein). Preferential uptake of the positively charged saliva proteins during the initial stages of the adsorption process is also concluded from the results of the kinetics experiments. Preferential adsorption of positive proteins is somewhat suppressed by the presence of Ca²⁺ ions in the medium. The results suggest that an acquired pellicle on a tooth in an oral environment contains a significant fraction of positively charged proteins. The positively charged proteins in the pellicle reduce the zeta-potential at the tooth surface to low values; consequently, electrostatic forces are expected to play only a minor role in the interaction with other components (e.g. bacterial cells).     

Ionic-conductivity switching of vinyl malachite green leuconitrile copolymers based on photoinduced carrier generation

Copolymers of bis[4-(N,N-dimethylamino)phenyl]-4-vinylphenylmethanenitrile (vinyl Malachite Green leuconitrile) with methyl methacrylate or ω-methoxyoligo(oxyethylene) methacrylate have been synthesized, aiming at designing one-component-type organic polymers for photoswitchable ion-conducting films. The triphenylmethanenitrile copolymers with ω-methoxyoligo(oxyethylene) methacrylate were found to undergo ionic-conductivity switching by turning on and off UV light at ambient temperature, owing to their low glass transition temperature. © 1993 John Wiley & Sons, Inc.     

Chemical studies on the anobiidae: Sex pheromone of the drugstore beetle, stegobium paniceum (L.) (coleoptera)

Chemical an spectroscopic evidence is presented to show that 2,3-dihydro-2,3,5-trimethyl-6-(1-methyl-2-oxobutyl)-4H-pyran-4-one (10) is the sex pheromone produced by the female drugstore beetle, Stegobium paniceum L.     

Synthesis of 1,8- and 2,8-dihydrocycloheptapyrazol-8-one derivatives by the reactions of 3-acetyltropolone and its methyl ethers with phenylhydrazine

3-Acetyltropolone ( 1 ) reacted with phenylhydrazine to give 3-acetyltropolone phenylhydrazone ( 3 ) and 3-methyl-1-phenyl-1,8-dihydrocycloheptapyrazol-8-one ( 4 ). The former ( 3 ) cyclized to afford the latter ( 4 ). The reaction of 3-acetyl-2-methoxytropone ( 2a ) with phenylhydrazine gave 4 , 3-methyl-2-phenyl-2,8-dihydrocyclo-heptapyrazol-8-one ( 5 ), and 3-methyl-2-phenyl-2,8-dihydrocycloheptapyrazol-8-one phenylhydrazone ( 6 ). The compound ( 5 ) reacted with phenylhydrazine to afford 6 . The reaction of 7-acetyl-2-methoxytropone ( 2b ) with phenylhydrazone gave 7-acetyl-2-methoxytropone phenylhydrazone ( 7 ), 7-acetyl-2-(N′-phenylhydrazino)-tropone phenylhydrazone ( 8 ), 3-methyl-1-phenyl-1,8-dihydrocycloheptapyrazol-8-one phenylhydrazone ( 9 ), and 6 . The compound ( 7 ) was heated to afford 4 and reacted with phenylhydrazine to afford 8 and 9 . The compound ( 8 ) was also refluxed to give 9 .     

Practical enantioselective synthesis of endothelin antagonist S-1255 by dynamic resolution of 4-methoxychromene-3-carboxylic acid intermediate

A practical multikilogram-scale synthesis of enantiomerically pure S-1255 (1), a potent and orally active ET(A) receptor antagonist, is described. Utilizing readily available starting materials and reagents, the entire sequence of reactions starting from 2,5-dihydroxyacetophenone 8 proceeded under mild conditions to give 1 in an excellent chemical yield (8 steps, 41% overall yield) and in a high enantiopurity (98% ee). The crucial step of the synthesis is a dynamic resolution of key intermediate 16. (R)-Methoxy acid (R)-16 having 97-99% ee was obtained in 83-84% yield from racemic 16 as a crystalline (1S,2R)-(+)-norephedrine or (+)-cinchonine salt by the dynamic resolution comprising concurrent crystallization and in situ racemization. A mechanism of the dynamic resolution through a ring-opened zwitterionic intermediate is discussed. In the final synthetic step, an effective carbon-carbon bond formation between the C4 carbon and the p-anisyl group was accomplished by a conjugate addition-elimination reaction of Grignard reagent 3 to (R)-16 to give 1 having 98% ee. Owing to high efficiencies of functional group transformations, carbon-carbon bond formations, and the dynamic resolution, the synthesis required no chromatographic purification and was amenable to a multikilogram-scale preparation. Several kilograms of 1 for clinical trials were successfully prepared by this process.