Conceptual design of spectrum changeable neutron calibration fields in JAERI/FRS

Spectrum changeable neutron calibration fields are planned to be established with an accelerator installed in Japan Atomic Energy Research Institute/Facility of Radiation Standards. The neutron fields are provided by bombarding a target surrounded by a moderator, with charged particles from the accelerator. In the fields, a wide variety of neutron spectra is provided with sufficient fluence rate for the calibration of dosemeters. In this study, necessity of the field was first discussed in view of relationship between readings of existing dosemeters and true dose equivalents where the dosemeters were used. Second, test simulation of neutron spectra was carried out with the Monte Carlo technique for some arrangements with a LiF target and quasi-cylindrical moderators with different materials. The simulated spectra were summarised in terms of fluence-average energy, fluence rate and calibration factor for the dosemeters.     

Copolymerization of 2-phenoxy-1,3,2-dioxaphosphorinanes with α-keto acids involving deoxygenation of the keto oxygen atom: deoxy-copolymerization

Summary The copolymerization of 2-phenoxy-1,3,2-dioxaphosphorinanes (4) with -keto acids (2) took place at room temperature without added catalyst to produce copolymers (5). The copolymer 5 is composed of phosphoric acid triester unit (5 ) and of -hydroxy-carboxylic acid ester unit (5 ). Unit 5 is an alternating unit of monomers 4 and 2 whereas unit 5 is formed by deoxygenating 2 by 4. 5 can be taken as copolymers of units 5 and 5 , the formation of the latter involving a deoxygenation process (Deoxy-Copolymerization). The ratio of 5 /5 (m-value in 5) increased in the order of unsubstituted (4a)-, 5,5-dimethyl (4b)-, and 5-t-butyl (4c)-phosphorinane systems. The reaction mechanism is also discussed.Dedicated to the 65th birthday of Professor G. Manecke     

Different expression of Bcl-2 protein in gastric adenomas and carcinomas

In order to cast light on the possible role of bcl-2 protein (Bcl-2) expression in gastric tumorigenesis, 33 cases of gastric adenomas and carcinomas originating from the same stomachs were immunohistochemically investigated for Bcl-2 protein (Bcl-2) expression, accumulation of p53 protein and cell proliferation as determined by the Ki-67 labeling index (LI). Bcl-2 expression was detected in 24/33 (72.7%) adenomas and in 6/33 (18.2%) carcinomas, the difference being statistically significant (P = 0.0001). Only 4 of 33 (12.1%) cases exhibited expression in both adenoma and carcinoma lesions in the same stomachs. Immunoreactivity was decreased in areas of cellular and structural atypia in adenoma lesions (P < 0.008), and appeared to be positively linked to the tumor progression and the degree of differentation in carcinomas, although it did not reach statistical significance. Accumulation of p53 protein was rare in the adenomas but was found in 15/33 (45.5%) of carcinoma lesions, with a significant dissociation from Bcl-2 immunoreactivity. No apparent relation between Ki-67 LI and either adenoma grading or carcinoma typing was noted, although average Ki-67 LI of the highest labeling areas in carcinomas was statistically higher than in adenomas (P = 0.0001). These results indicate that the regulation of Bcl-2 expression may differ between gastric adenomas and carcinomas, may be correlated with tumor differentiative features. In addition, p53 accumulation may play an important role in the onset of malignancy.     

Polyethylenimine–polyepichlorohydrin interpolymer for chelating ion-exchange membrane

Polyethylenimine membranes consisting of linear polyethylenimine (PEI) and polyepichlorohydrin (PECH) were prepared by casting and heating an N,N-dimethylformamide solution of the two polymers under nitrogen at 100°C for 60 min. The membrane was also prepared by a heat-press method in a conventional manner. The cast membrane obtained was transparent. The membrane has a crosslinked structure due to the reaction between the secondary amino groups in PEI and the chloromethyl groups in PECH. Although a larger feed ratio of PEI/PECH gave membranes with a larger adsorption capacity for Cu²⁺ ions, the optimum ratio was 40/100 with respect to mechanical properties. A belt conveyor system using the PEI membrane was able to transport Cu²⁺ ions from one bath to another. In a diffusion dialysis against 1N HCl, the PEI membrane crosslinked rather tightly showed a specific ion-selective transfer character. For example, in Cu²⁺–Ca²⁺ system the permeability ratio P_cu/P_ca was about 3.8. The selectivity arises from the difference between affinities (extractabilities) of PEI toward metal ions. The selectivity was changed depending on the pH value.     

Reactions of organoboron polymers prepared by hydroboration polymerization

Summary Hydroboration polymerization of diolefin gives an organoboron polymer, which can be regarded as a polymer homologue of trialkylborane. The organoboron polymers obtained were reacted with ,-dichloromethyl methyl ether (DCME) followed by the oxidative treatment to produce the corresponding poly(alcohol)s in high yields.Part II: Polym. Bull. 25,1 (1991)     

Synthesis of an amphigel by the terpolymerization of 2-methyl-2-oxazoline, 2-alkyl-2-oxazoline,and bis-oxazoline

Summary The terpolymerization of 2-methyl-2-oxazoline, 2-alkyl-2-oxazoline (alkyl = n-butyl, n-octyl, n-dodecyl), and 2,2-tetramethylenebis(2-oxazoline) was carried out with methyl trifluoromethanesulfonate initiator. The obtained gel was isolated in a moderate yield after Soxhlet extraction. The resulting gel showed a characteristic property as an amphiphilic gel (amphigel), i.e., it was swollen both in water and in organic solvents such as N,N-dimethylformamide (DMF), n-propanol, 1,2-dichloroethane, diethyleneglycol dimethyl ether (diglyme) and toluene.     

PbTiO3-PbO-B2O3 Glass-Ceramics by a Sol-Gel Process

PbTiO₃ (PT)-PbO-B₂O₃ glass-ceramics were produced by a sol-gel process. Achievement of high PT content at levels unattainable by conventional glass-ceramics preparation methods was semiquantitatively shown. PT content was similar to the designed PT volume fraction and seemed rather unaffected by the composition of the glassforming component at a calcination temperature of 700°C. A higher ratio of PbO to B₂O₃ in the glassforming component resulted in a low PT crystallization temperature, <500°C. PT crystals 1-2 μm in size were obtained at calcination temperatures >600°C.     

Preparation of Stoichiometric Fine Lead Barium Titanate Powder

Lead barium titanate powder with 0.03–0.15 μm particle sizes was prepared from lead barium titanyl oxalate which was previously prepared by reacting high-purity ammonium titanyl oxalate with barium and lead acetate. The critical factor in preparing the barium titanyl oxalate was the reaction time. It was necessary to allow 2–4 h to synthesize the oxalate to get a single-phase barium titanate. The critical factors in preparing the lead titanyl oxalate were pH and the concentration of the solution. It was necessary to adjust the pH to around 0.5 and the concentration to <0.08 M . When lead barium titanyl oxalate is prepared, low pH, low concentration, and a long reaction time are necessary.