Browsing by Author "Gandhimathy Selvaraj"

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    CORK SCREW PETRI DISHES FOR PLASTIC FREE SEALING
    (2024) Rageshwari Selvaraj; Vinodkumar Selvaraj; Muthukumar Muthamilselvan; Gandhimathy Selvaraj; Melvin Joe; Anbukkarasi Kaliyaperumal; Akshaya Subbaiah Balamurali
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    LARVICIDAL PROPERTIES OF PSYCHOTRIA OCTOSULCATA (W. A. TALBOT.) (RUBIACEAE) CRUDE EXTRACTS ON HUMAN VECTOR MOSQUITOES AEDES AEGYPTI (LINN.), CULEX QUINQUEFASCIATUS (SAY.) AND ANOPHELES STEPHENSI LISTON
    (Journal of Entomology and Zoology studies, 2018-01) Gandhimathy Selvaraj; Jeyasankar Alagarmalai
    Psychotria octosulcata plant extract potential in controlling mosquito larvae was investigated. The crude extracts from the plant leaves were obtained by soaking method using the solvents such as ethyl acetate, chloroform and hexane. The crude extracts were subjected to larvicidal activity of Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi of IV th instar larvae at 48hrs. An. stephensi showed maximum larvicidal activity at a minimum LC 50 value of 58.2ppm for ethyl acetate extract. Above 90% mortality was observed for ethyl acetate extract at LC 50 62.2ppm and 65.7ppm for C. quinquefasciatus and A. aegypti respectively. The hexane also showed above 90% mortality for three species at 60-68ppm and chloroform showed comparatively lower mortality than other two solvents. The microscopic observations suggest that the extract has produced physical and physiological inconvenience for the survival of larvae. The results indicate that the plant extract has phytochemicals that are efficient to control mosquito larvae.
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    MIDDLE SCHOOL STUDENTS' KNOWLEDGE ABOUT STATIC AND DYNAMIC ARTEFACTS STUDIED THROUGH THEIR DRAWINGS AND DESCRIPTIONS
    (MacMillan/Homi Bhabha Centre for Science Education, TIFR, 2009-01) Gandhimathy Selvaraj; Ritesh Khunyakari; Chitra Natarajan
    This paper reports a study of students' understanding of artefacts through their drawings and descriptions. The experimental design of the study carried out with 12 middle School students (ages 11- 13 years) involved four stages: pre-test, intervention and post-test, followed by a semi-structured interview of each student. The intervention activities engaged students in filling a questionnaire by estimating and measuring dimensions of a variety of artefacts of common shapes and sizes, writing their descriptions, and in repairing a bicycle. The study analysed students' paper-pencil productions in the tests and the questionnaire, and audio and video data collected during the intervention and interviews. The effect of the intervention on the nature of depictions of proportions and dimensional attributes in the drawings depended on the context of problem solving. Interviews helped to make explicit the meanings ascribed by students to the descriptions and the strategies used by them in their object depictions. The study highlights the importance of engaging students in authentic contexts of problem solving, and making drawings in such contexts.