ジメチルホルムアミド(DMF)中の金属塩化物のEDTAによる伝導度滴定において二,三の塩の添加による(反応点)の単一化を検討した.EDTAによる伝導度滴定では,置換反応の後にキレート反応が起こり両方の反応点が順次現れる.置換反応ではEDTAのカルボキシル基のプロトンにDMFと金属塩化物との付加陽イオン種が置換する点として4:1,2:1の反応比の点にが現れ,その後に1:1のキレート反応点を得る.このように種々多くの点が得られ複雑なため,本報では二,三の塩の添加によりを少なくすることを試み,併せて二者共存時のEDTAによる示差滴定を検討した.シュウ酸,硝酸,硝酸リチウム及び過塩素酸アンモニウムを添加すると置換反応点の2:1がマスクされを少なくすることができた.

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Objective analysis of the radiographic characteristics of the alveolar bone is critical in prosthodontic treatment. The author investigated basic items on the classification of the radiographic image of the alveolar bones based on the quantitative analysis and on the calibration system on many films for the observation of their clinical course after the treatment.
In a number of cases of the radiographs of lower alveolar ridge, density distribution was analyzed for quantitative classification with emphasis placed on the internal structure of the alveolar bone, and the density distribution of the periodontal alveolar area was also analyzed quantitatively.
Results and Conclusions
1) The several linear analytical value in the particular area must be required to classify the radiographic image of the alveolar bone because of the marked differences of linear analytical value in the narrow area on the radiographic image of the alveolar bone.
2) The lamina dura in the tooth neighboring the edentulous area was wider than the one on the counter side of it and the one of abutment tooth for a fixed bridge.
3) The width of the periodontal space was almost the same because of small individual variations and less influence by the presence or absence of the adjacent tooth. The average of the width for all the cases showed 0.23±0.08mm.
4) Density in the area corresponding to the lamina dura and the periodontal space which were calibrated in a step wedge equivalent markedly varied between individuals and between areas.

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We measured the creep of polyvinyl chloride fibers at 20°C and 40°C, and constructed the master creep curves by basing the key to the procedure for generalization upon O'Shughnessy's assumption that there exist an invariant pattern in logarithmic time for the entire delayed elongation process but that the time scale of the response, as well as its magnitude is dependent on stress.
The characteristic retardation times, Log τ, plotted as function of stresses, decreased linearly as stresses increased. The instantaneous elastic elongation E₀, plotted as function of stresses, increased linearly where stresses (S) were relatively small, but these relations between E₀ and S deviate from linear relations where stresses were relatively large and these deviations suggested the structural change in PVC fibers. The reciprocals of scale factors, 1/f, plotted as function of stresses well indicate the stress dependence of retarded elastic deformation of PVC fibers.

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