Hiroshi Hirotani

type:Article 大阪教育大学・教職実践演習ミニ講座「理科の実験・観察における安全」(2018年度)より,ICT教材を活用した授業実践について報告する。この講座では,理科の実験・観察を安全に行うために必要な知識を習得し,それを支える理論的根拠や経験知についてもディスカッションを通して深く理解することを目的としている。本稿にて報告する授業実践では,酸・塩基の中和実験(高校化学基礎)を撮影・編集した動画をICT教材として用い,実験時に事故を誘発し得る危険な兆候を察知する練習を行った。そして,そのような危険な兆候として,実験中の生徒の立ち位置・姿勢が悪いこと,実験卓上の整理整頓の不徹底等を見出した。 A course to learn how to safely conduct scientific experiments and observations is offered for prospective teachers (fourth grade students in Osaka Kyoiku University). This paper reports a practice in a class consisting of the course held in 2018. A video material is edited as an ICT teaching material, in which an experiment on neutralization of acids and bases is conducted in a first grade high school chemistry class. The practice in this report is aided by the ICT teaching material. The prospective teachers in the class are trained to find indications of danger in the laboratory through the video material.

Water quality parameters in the water column of a dam reservoir were measured monthly in 2001. From July to November, the vertical profiles of alkaline phosphatase activity (APA) and related parameters were examined in detail. APA increased during the summer in epilimnion while it was almost stable in hypolimnion. A small increase in APA was observed at a depth immediately above the bottom of the lake. APA fluctuation was independent of soluble reactive phosphorus. It was assumed that APA is not indicative of the phosphorus status of aquatic microorganisms in the lake. A positive correlation was observed between chlorophyll a content and APA in the photic zone. In the aphotic zone, APA correlated positively with the colony count of heterotrophic bacteria, but not with microscopic total bacterial count.

Fluctuations of alkaline phosphatase activities in two streams and in reservoirs receiving the stream waters located in two adjacent but not connected watersheds were investigated from January to December in 2000. Alkaline phosphatase activities (APA) remained nearly constant in both streams, whereas in reservoirs they increased during the summer season. No relation was found between APA and soluble reactive phosphorus concentration. At one sampling station located in the stream, phosphorus concentration extraordinarily increased later in the study, but there were no related change observed in APA. An examination of size-fractionated samples suggested that most the APA in stream could be attributed to dissolved enzymes, whereas in reservoir most APA was related to bacterial particles. It assumed that APA is not indicative of phosphorus status of aquatic microorganisms.

Dryobalanops aromatica and D. Ianceolata (hereafter denoted as Lin and Dl, respectively) are major Dipterocarp species constituting an emergent layer in the Bornean Rain Forest, and their distributions are in proximity, but never overlap. Thus, we examined the relationship between the distribution of these species and soils with reference to the soil physico-chemical, morphological, and microbiological properties, <BR>Based on the topographical investigation, was located only on the upper slope, whereas Dl occupied on both upper and lower slopes. The soil solums examined around these two species were always deeper than 1,3 meter. Soil texture was always sandy for the soils around Da, on the other hand, ranging from sandy te clayey for these around Dl. Furthermore, the following differences were found; 1) organic layer was thicker {n the Da soils, 2) soil color of subsurface horizons was duller in the Dl soils, and 3) only the Dl soils contained coarse fragments. 4) the amounts of exchangeable cations such as Ca and/or Mg and total oxides' content of K₂O, MgO, and P₂O₅ were higher for the Dl soils, 5) the amounts of exchangeable At and H were higher in the Da soils, 6} proportion of air phase and volume of macropore, and the value of sand content were higher for the Da soils, showing that the Da soils easily attain to drier soil moisture condition after rainfall, which was proved by monitoring soil water potential, 7) ten times as much fungal colonies were detected in the Da soils as compared to the Dl soils.<BR> These result$ suggest that Da emerges on a sandy soil with a dominance of drier soil moisture condition for some period and a low nutrient status with high acidity on the reflection of stable pedogenetic processes, while Dl stands on either clayey or sandy soil with a dominance of reductive condition for a certain period and relatively high nutrient status with low acidity, reflecting weak pedogenctic processes. It was well-known that shifting cultivators utilize a land where Dl dominates as a productive crop field, Their traditional way of land selection proves to be rational from the standpoint of soil science.

An antiviral substance produced by phototrophic bacteria was partially purified. The characteristics of this substance were as follows: 1) The substance inhibited the replication of Poliovirus type I at the concentration of 0.1μg/ml. 2) Antiviral activity of the substance was enhanced by Cu cation or ascorbic acid at a concentration of 1μg/m1 or 50μg/ml, respectively. 3) Antiviral activity of the substance was inhibited by Fe cation at a concentration of 10μg/ml. Studies for the detection of an antiviral substance similar to that produced by phototrophic bacteria were carried out in several fresh vegetables.

1) It was observed that the phototrophic bacteria, Rhodopseudomonas capsulata produce a substance that inactivates the Sindbis virus and the T_5 phage of E. coli. 2) The molecular weight of the antiviral substance was below 10,000 and the substance was neither a protein nor a high molecular nucleic acid. 3) The active subtance exhibiting the antiviral activity was found to be relatively stable upon heating (60℃) under dark condition. The activity of the antiviral substance increased when it was kept in contact with the virus under light condition. However when the extraction was performed in the light; the activity tended to decrease. Therefore, it is concluded that the antiviral substance should be extracted under dark condition as much as possible.