Sarangbanua plant, known as Clerodendrumfragrans Vent Willd, is a division of the Verbanaceae family found in Simalungun district of Indonesia, which is traditionally used as medicinal plants. The antioxidant and antibacterial activities of the C. fragrans leave extract was prepared by dissolving it in non-polar to polar solvents and treated by DPPH (1,1diphenyl-2-picrylhydrazin) and diffusion methods. The results showed that the ethanol (polar) extract of the C. fragrans leaves had the highest antioxidant activity than ethyl acetate (semi-polar) and n-hexane (non-polar) extracts, which had IC 50 values of 22.37 ppm, 27.26 ppm, and 88.77 ppm respectively. Vitamin C as a positive controlled with the IC 50 value of 20.18 ppm. Furthermore, the ethyl acetate (semi-polar) extract of the C. fragrans leaves had the greatest inhibition value on Gram-positive bacteria of S. aureus (90.0%)with inhibitory zones of 11.25 ± 0.2 mm, meanwhile the n-hexane (non-polar) extract had the greatest inhibition against Gram-negative bacteria of the E.coli(77.21%)with inhibitory zones of 10.5±0.3 mm.

This research aimed to provide an innovative chemistry learning material with guided tasks to improve students’ competence in Chemistry. It involved 180 students enrolled in the Analytical Chemistry course at State University of Medan in academic year of 2016/2017. The samples were purposively selected and divided into two groups. The research consisted of several steps including enrichment, innovation and standardization of learning material, followed by implementation of the developed learning material in class. A set of good quality learning material equipped with the guided task for Gravimetry topic has been provided. It contained relevant contextual examples, laboratory works, students’ activities, multimedia, and hyperlink to trustworthy websites. Implementation of innovative learning material has been conducted by using a set of developed learning material in the experimental class while the existing textbook was used in the control class. The research findings highlighted several points: (1) well-implemented innovative learning material was effective to improve the students’ competence; (2) learning outcome in experimental class was found higher than that in control class; (3) the guided task in the learning package facilitated the students to learn the selected chemistry topic independently which in turn shifted student learning style from lecturer-oriented to student-oriented; (4) the guided task not only made the students be familiar with searching for scientific documents to complete the given tasks but also improved the students’ ability to write and organize their assignments; (5) students’ academic attitudes, observed during the learning activities, were categorized as very good. Keyword: innovative learning material, guided tasks, independent learning, students’ competence.

No abstract

This study aimed to understand level of feasibility of learning media based-Lectora Inspire for special topic of acids and bases developed according to BSNP standard for interactive computer media; and to know the differences of the improvement of students is conceptual skills in learning acids and bases studied by using computer media of Lectora Inspire developed with power-point. It used R & D method (Development Research) with model ADDIE. The population of this study was students of class XI and teachers in MAN 2 Langsa, and lectures of Postgraduate Program of Chemistry Education at State University of Medan. Sample in this study was students of class MIA 1 and MIA 2 which have 30 students for each class. The BSNP questionnaire was used as the instrument after had been integrated with computer interactive media, and multiple choice questions used to measure students conceptual skills. Data were analyzed using descriptive method and statistical analysis with independent sample t-test. The result showed that: the developed learning media of Lectora Inspire was categorized with level of very feasible by content feasibility of 4.8 and presentation feasibility of 4.7, and there was the difference of students conceptual skills (Ngain of students) for special topic of acids and bases that learned using computer media of Lectora Inspire which had been developed with power-point media (0.041).

Amylase is an enzyme that plays a role in hydrolyzing starch to simple sugars. This protein is very important for various industrial processes. Microorganisms are considered as the best source of amylase production. This study was aimed at isolating and dentifying amylolytic bacteria from rice soil samples that have the potential to produce amylase enzymes. Rice soil samples were collected from two locations, namely the Percut Sei Tuan area and Labu Beach. Samples was isolated, then macroscopically identified with microscopy, and microscopically characterized with catalase test, endospore staining and gram staining. The identification results showed that 14 bacterial isolates from the two samples potential to produce amylase enzymes. The isolates which were characterized with catalase test showed positive results for all isolates. The characterization results with endospora staining showed 7 positive isolates and 7 negative isolates. Likewise with the results of gram staining characterization. Thus, from the two sample locations obtained amylolytic bacteria that potentially produce amylase enzymes.

No abstract

This research aims to implement the Virtual Lab media using Problem Based Learning assisted to increasing the students' learning achievements in Cahaya Medan High School and finding out whether there are differences in student learning achievements using virtual lab media and Problem Based Learning models in terms of the STIFIn test and learning style tests This study uses a pretest-posttest group design. Data analysis techniques using One Way Anova analysis. The results showed: (1) there were differences in the increase in students' chemistry learning achievements in terms of the STIFIn test, and (2) there were differences in the increase in students' chemistry learning achievements in terms of learning style tests.

Sarangbanua traditional medicinal plant is found in Simalungunand NorthTapanuli Regencies, Sumatera, Indonesia. The result of plant determination, sarangbanuais Clerodendrumfragrans Vent Willd, including the Verbenaceae family. This study aims to determine the toxicity of the three types of leaf extracts of C. fragrans Vent Will. The Brine Shrimp Lethality Test (BSLT) method was used to determine the toxicity of the extracts. The mortality data were then analyzed by Probit SAS to obtain LC50 values. The results showed that the three types of C. fragrans leaf extracts had LC50 values below 1000 µg/mL, so they were classified as toxic and potentially bioactive. The LC50 values of each of the ethanol, ethyl acetate and ethanol extracts were 26.25; 37.50 and 41.97 µg/mL