著者

富田 達

出版者

地学団体研究会

雑誌

地球科学 (ISSN:03666611)

巻号頁・発行日

vol.1956, no.26-27, pp.36-51, 1956-03-25 (Released:2017-07-24)

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Many data on the radio-effects in zircon are examined with the following results: (1) Zircon is subdivided structurally into three groups : Group A-Non-metamict zircons, includimg normal zircon and transparent hyacinth (G>4.6 or 4.55); Group B-Partly metamict zircons (G=4.6-4.0); Group C-Completely metamict zircon or typical malacon (G=4.0-3.9 or less). (2) In the damage process in zircon are recongnized three stages: Stage I-a continuous change from normal zircon to transparent hyacinths up to a certain saturation of ionization by free elections, the degree of which is shown in the colour order: colourless-yellow-orange-pink-purple; Stage II-a biscontinuous change from Group A to Group B. This change involves the abrupt partaking of radiogenic dissociation (ZrSiO_4→ZrO_2+SiO_2) occurring in part within a single crystal. Megascopic translucency or nearly opaque character carrying with yellowish and/or greenish tinge is an indication of this change; StageIII- a continuous increase of the dissociation products in Group B. This stage ends with the formation of Group C, opaque and green or brownish-green. (3) Time has a becibebly greater effect than alpha-activity. Most of the post-Cambrian granite zircons do not show so wide a range of variation of 2θ as seen in the pre-Cambrian, and less damaged crystals are present among the Miocene zircons. (4) A series of zircon from the Middle Cretaceous granites in Japan exhibits the general tendency that the later members are of greater radioactivity. This may be a reflection of the evolution of granitic magma, which becomes more enriched in the radioelements in its later stages. (5) Radio-effects in zircon are gradually restored by heating. Naturally heated zircons are met with in granitic xenoliths often found within volcanic rocks. Colour of these zircons corresponds with the age of the volcanic rocks. This suggests a means of age-determination for volcanic rocks.

著者

三嶋 直之 富田 達洋 松原 秀憲 簗瀬 武史 吉成 正雄

出版者

公益社団法人 日本口腔インプラント学会

雑誌

日本口腔インプラント学会誌 (ISSN:09146695)

巻号頁・発行日

vol.27, no.4, pp.541-548, 2014-12-31 (Released:2015-02-01)

参考文献数

25

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The aim of this study was to examine the possibility of repeated heat-pressing of pressable glass-ceramic by evaluating the influence of repeated heat-pressing on mechanical properties, surface characteristics and dimensional accuracy. A commercially available pressable glass-ceramic system (IPS e.max Press, Ivoclar Vivadent, Liechtenstein) was selected in this study. Disc samples with 12.5 mm in diameter and 1.3 mm in thickness were heat-pressed and used as the first heat-pressing specimens. Sprue and button parts of the first heat-pressed specimens were retrieved, and they were used to construct the second heat-pressed specimens. The third heat-pressing groups were constructed in just the same way as the second heat-pressing groups. All the heat-pressing procedures were performed according to the manufacturers' instructions. After the arithmetic mean surface roughness (Ra) of pressed specimens was measured, a biaxial flexural strength (BFS) of disc specimens was measured using a universal testing machine. Surface hardness, optical microscopic and scanning electron microscopic observations were carried out. Surface characteristics were examined with X-ray diffractometry (XRD) and electron probe microanalysis (EPMA). The dimensional accuracy of a heat-pressed full crown was also evaluated. The Ra values ranged from 4.0-4.3 μm of all heat-pressing groups. The BFS values obtained were 346±29 MPa, 312±24 MPa and 305±20 MPa for the first, second and third heat-pressing group, respectively. The third heatpressing group showed a lower BFS mean than the first heat-pressing group (p=0.038). Surface hardness showed around 540 Hv in all heat-pressing groups. Microscopic observations revealed that small amounts of porosity were observed in all heat-pressing groups with no differences among the number of heat-pressings, and that the apparent lithium disilicate crystals were confirmed by XRD. A compositional change was not recognized in all heatpressing specimens by EPMA. The dimensional change of all heat-pressed full crowns ranged from +0.16-0.19% with no differences among the number of heat-pressings. These results demonstrated that the repeated heatpressing of pressable glass-ceramics used in this study was available with a slight decrease in strength and no differences in surface characteristics and dimensional accuracy.

著者

宮久 三千年 木下 龜城 富田 達

出版者

日本地質学会

雑誌

地質學雜誌 (ISSN:00167630)

巻号頁・発行日

vol.59, no.694, 1953-07-25

著者

富田 達夫

雑誌

情報処理

巻号頁・発行日

vol.57, no.7, 2016-06-15

著者

飯田一朗 武理一郎 森田俊彦 富田達夫

雑誌

デジタルプラクティス (ISSN:21884390)

巻号頁・発行日

vol.5, no.4, pp.284-290, 2014-10-15

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