JOSA year 15 no. 4 (33)
eISSN 2068-3049

CONTENTS

SECTION A – Mathematics

1. HOW TO FIND THE INVERSE OF A MATRIX IN LORENTZ SPACE

(Mustafa Bilici, Ergin Bayram) / 315

2. SURFACE FAMILY WITH A COMMON NATURAL LINE OF CURVATURE LIFT

(Evren Ergün, Ergin Bayram, Emin Kasap) / 321

3. RESEARCH ARTICLE ASSESSING HIGH SCHOOL STUDENTS’ MATHEMATICS COMPETENCY: USING VISUAL IMAGE OF CONVEX FUNCTION GRAPH, CONCAVE FUNCTION TO PROVE THE INEQUALITY

(Nguyen Huu Hau, Nguyen Tien Da) / 329

4. TEACHERS ASSESS STUDENT’S MATHEMATICAL CREATIVITY COMPETENCE IN HIGH SCHOOL

(Tran Trung Tinh) / 335

SECTION B – Chemistry

1. PHYTOCHEMICAL SCREENING AND IN-VITRO EVALUATION OF ANTIOXIDANT, CYTOTOXICITY, ANTIFUNGAL ACTIVITIES OF KALANCHOE PINNATA (L)

(Roy Abhijit) / 343

2. THE INFLUENCE OF HEAT TREATMENT ON STRUCTURAL AND MECHANICAL PROPERTIES OF THE NICKEL-BASED ALLOY BC1

(O. Ben Lenda, F. Sabir, S. Saissi, K. Marbouh, S. Elhamzi, L. Zerrouk, A. Ibenlfassi, R. Boulif, E.Saad) / 351

3. STRUCTRUAL HARDENING MECHANISM OF LEAD-CADMIUM-BISMUTH-MAGNESIUM ALLOYS (PbCdBiMg) FOR BATTERY GRIDS FOR THE NEW GENERATION

(S. Saissi, K. Marbouh, F. Sabir, O. Ben Lenda, S. Elhamzi, L. Zerrouk, A. Ibnlfassi, Y. Ait Yassine, E. Saad) / 363