Composition and characteristics of glass ionomer cements
Article Abstract:
Glass ionomer cements are a combination of a silicate glass powder and a polyacrylic acid liquid. The resulting product, first developed in the early 1970s, is strong, rigid, fluoride-releasing, adhesive, and biocompatible. The original glass contains SiO2, AlO2, CaF2, AlPO4, and Na3AlF6. Later modifications have made the cements less water sensitive with a longer working time. Gelation has been retarded by adding dicarboxylic or tricarboxylic acids and the resulting material is more reactive. The positive isomer of tartaric acid both prolongs working time and increases the setting rate, while toughness has been improved by adding water-soluble polymers or inducing polymerization in the cement itself. These also make the cements stronger. The setting rate depends on a reaction between the glass and the poly-acid liquid and varies with composition. The availability of glass ionomer cements with different characteristics allows a variety of clinical uses and, in fact, has led to the design of formulas specifically geared toward a particular clinical problem. Limited information is available on the exact chemical composition of most commercially available materials. As clinical trials test the properties of these cements, it is hoped the results will encourage better specification of criteria for their use. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journal of the American Dental Association
Subject: Health
ISSN: 0002-8177
Year: 1990
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Kancil: from mischief to moral education
Article Abstract:
The mouse-deer character Kancil in Indonesian folktales has changed in response to his new role in modern children's stories. In the traditional tales, Kancil is an important character who uses his wits to defeat more powerful animals. He represents the resentments and revenge fantasies of the 'little man' who feels powerless in the face of forces beyond his control. The modern stories for children have a more explicit moral, and Kancil has become asexual, juvenile and wise rather than cunning. The changes reflect the adaptation of Kancil to support institutional values of the modern state.
Publication Name: Western Folklore
Subject: Regional focus/area studies
ISSN: 0043-373X
Year: 1992
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Plug and play
Article Abstract:
Intel Corp's new Universal Serial Bus (USB) offers a simple way of adding peripherals such as scanners to a PC. It automatically communicates with the PC, and in many cases allows a new product to be used immediately. It can supply power to devices such as modems, and allows add-ons to be plugged in from the front of the PC, rather than the back. Once peripherals are installed, they can be attached and removed at will very simply.
Publication Name: Far Eastern Economic Review
Subject: Business, international
ISSN: 0014-7591
Year: 1997
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