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Volume 49, Issue 4
Displaying 1-4 of 4 articles from this issue
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Tatsuya Tomioka, Chisato Takahashi, Chika Takai, Mitsuo Utsuno, Masayo ...2012 Volume 49 Issue 4 Pages 260-266
Published: April 10, 2012
Released on J-STAGE: April 27, 2012
JOURNAL FREE ACCESSEffect of pH change on the shell thickness of calcium carbonate hollow particles was investigated. Calcium carbonate hollow particles were synthesized at different pH change rates by Carbon dioxide bubbling into a solution. And influence of pH change rate on the shell thickness was estimated by observing SEM images of cross section of hollow particles. pH change curve could be divided into two stages, before and after the point where pH changes rapidly, and could express each stage with the approximated curve. Rate parameters of pH change rate were determined from these approximated curves, and the relation with shell thickness was investigated. As a result, it has become clear that thickness of hollow particles is expressible by the rate parameter of approximation curve corresponding to the first stage which is characterized as the process from start of bubbling to the point where shell is formed.View full abstractDownload PDF (1168K) -
Toshiyuki Nomura, Akinori Yoshihara, Hayato Tokumoto, Yasuhiro Konishi2012 Volume 49 Issue 4 Pages 267-273
Published: April 10, 2012
Released on J-STAGE: April 27, 2012
JOURNAL FREE ACCESSFrom the view point of fine particle technology, the effects of surface properties of methanogens, which are related to the rate-limiting step in the methane fermentation process, on their adhesion and aggregation were examined. As a result, Methanosarcina barkeri were found to be charged negatively and their isoelectric point was around pH 2. In contrast, Methanosaeta concilii was found to be non-charged and their isoelectric point was around pH 4.5. According to the ATR-FTIR analysis and acid-base titration, it was guessed that the difference of surface potential between two types of methanogens was due to the difference of the amount of carboxyl group and phosphate group on their microbial surface. Methanosarcina barkeri showed better adhesion to not the negatively-charged glass but to the positively-charged one. Percent aggregate of Methanosarcina barkeri increased with an increase in the ionic strength of the cell suspension. In contrast, percent aggregate of Methanosaeta concilii was almost constant regardless of the ionic strength. These adhesion and aggregation phenomena could be understood by the electrostatic interaction and the change of free energy of interaction between methanogen and slide glass.View full abstractDownload PDF (668K) -
Takayoshi Kiguchi, Takamasa Mori, JunIchiro Tsubaki2012 Volume 49 Issue 4 Pages 274-280
Published: April 10, 2012
Released on J-STAGE: April 27, 2012
JOURNAL FREE ACCESSThe particle assembling state in a slurry affects the production quality or performance in ceramic industry and so on. Generally, to control the assembling state dispersants are added However, it is difficult to control it precisely because the adsorbing mechanism of dispersants has not been clarified enough. We have tried to make clear the adsorption mechanism of dispersant mainly through the observation of desorption behavior of the adsorbed dispersant. A mono-carboxylate and a polycarboxylate were used as dispersant, and two kinds of pure alumina powder were used : one contains Mg as sintering aid and the other one doesn't. It was found that the hydrophilic carboxyl groups in dispersants adsorbs on alumina particles electrostatically. In addition it was shown that polycarboxylate strongly adsorbs on alumina powder since it has a lot of carboxyl groups in a molecule. Furthermore, when containing Mg into alumina powder, dispersants should associate to Mg on the particle surface, resulting in much stronger adsorption.View full abstractDownload PDF (690K)
Review: Frontier Research Series
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Takashi Shirai2012 Volume 49 Issue 4 Pages 281-290
Published: April 10, 2012
Released on J-STAGE: August 04, 2015
JOURNAL RESTRICTED ACCESSIn recent years, the author has faced threats of global warming and depletion of energy resources. The ceramic industry adversely affects the environment. Its energy consumption per product is high because it requires a long period of heating at high temperature during manufacturing and because it emits many greenhouse gases such as carbon dioxide during the manufacturing process. The author has been studying toward simplifying and shortening the ceramic manufacturing process from forming to sintering aiming at reducing the environmental load using the utilization of the unique reaction field of an electromagnetic field environment created by microwaves. The microwave heating has various features such as selective heating and internal heating, and it offers the possibility of an energy-saving effect through effective energy consumption. In this paper, the recent topics of our research using microwave technology for development of ceramics manufacturing process are introduced, and the future of ceramics manufacturing process is discussed from the viewpoint of environmental load reduction.View full abstractDownload PDF (1462K)
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