Flavonoid compound from durian shell biowaste was identified by phytochemical assay and FTIR spectrophotometric methods. Total flavonoid content determined by the aluminum chloride (AlCl3) method using a UV-Vis spectrophotometer. Durian shells, which are a waste that causes the environmental problem, can be used as a source of potentially valuable flavonoid compounds. Flavonoid has antioxidants ability that is beneficial and useful. Durian shell used in this research consists of three types, namely Malika, Malon, and Monti, which are from local Indonesian durian. Based on the result, proximate test analysis showed that three local durian shell samples generally had a water content of 7%, a fat content of 0.9%, the protein content of 4.9%, an ash content of 8.5%, and a 78% carbohydrate content. The results of the analysis of the three durian shell samples did not show significantly different results. Then for the phytochemical assay, three local durian shell samples contained phenols, steroids, and terpenoids, the results of the phytochemical assay showed that there were more phenolic groups than the flavonoid group. The following analysis result is the functional group of three samples using Fourier Transform Infrared (FT-IR) spectrophotometer shows that the three types of durian shell samples have a band that is slightly different from the standard, but the number of waves in this band is similar to the standard quercetin. Then for total flavonoid levels in local durian shell using the aluminum chloride (AlCl3) method, the result is Monti durian shell having higher flavonoid levels, each 0.405 ± 0.002 mg QE/g, compared with each other shell type namely Malika and Malon of 0.321 ± 0.003 mg QE / g and 0.324 ± 0.002 mg QE/g, respectively. Thus in this study shows that Indonesian local durian shell contains significant total flavonoid content without the need for extraction. Samples were only dissolved with ethanol solvent, then a series of tests were carried out, then a series of tests were carried out, ranging from phytochemical assessment, FTIR spectrophotometer, and AlCl3 methods to determine the total flavonoid content through quantitative.
This research is a mix method research with the design of sequential explanatory strategy. This research aims to know and describe students’ conceptual understanding of buffer solution material and to get student response to teaching material of multiple representation buffers (macroscopic, submicroscopic, and symbolic). Research subjects were 114 students from eleven grade of natural science class (XI MIPA 3, XI MIPA 4, and XI MIPA 5), state senior high school 12 (SMA Negeri 12) Semarang, Indonesia, academic year 2017/2018. Quantitative data was collected through a diagnostic test in the form of three-tier multiple choice test totaling 20 items and questionnaires to find out the student’s response to multiple representation of teaching materials. Qualitative data is obtained by interview to confirm student answers. Multiple representation materials validated by three validators and received very excellent results with an average score of 190.33 from 212. The average score of the questionnaire was 30.026 with a proper category, and Alpha Cronbach reliability was 0.884. The results of this study indicate that the understanding of the concept of students on the material of buffer solution as much as 47.061% understand, 29.868% less understood, 12.763% misconception, and 10.307% do not understand.
PET (polyethylene terephthalate) waste is a plastic bottle waste that difficult to recycle in large scale, so it was causing environmental pollution. In this research, PET waste used as a main material of bricks by using the mix design method. The mix design method used includes cutting of PET waste, melting of PET waste, mixing with other materials, and molding the materials. This research used four variations of PET waste added by cement and sand to find the ideal composition that mentioned by SNI (Indonesia National Standard). The ideal composition of brick is solid plastic: cement: sand volume ratio is 66:22:12. The result of this research showed that brick quality is ideal, which was characterized by FT-IR and SEM. This composition has 0% of water absorbency, the compressive strength is 75 Kg/cm2, water absorbency of SNI brick is under 20%, and the compressive strength is between 60-100 Kg/cm2.
Teaching and learning activities in the classroom are part of the educational process aimed at bringing to a better state. These activities will be more meaningful if the needs and experiences of students are considered. Thus, this can improve the learning objectives which is connecting the subject matter subject to real-world problems. The purposes of this research are (1) to get student response toward teaching materials of multiple Representations-Chemoentrepreneurship (entrepreneurship in the chemistry field) and (2) to know and describe the influence of entrepreneur interest toward student learning outcomes. This research is the mixed method using by the model of sequential explanatory. Research subjects were 114 students from eleven grade of natural science class (XI MIPA 3, XI MIPA 4, and XI MIPA 5), state senior high school 12 (SMA Negeri 12) Semarang, academic year 2017/2018. Quantitative data obtained through a three-tier multiple choice test. Qualitative data collected through questionnaires to determine the response of students towards teaching materials and through questionnaires. Based on this data, we can assess of student entrepreneur interest. The teaching material was validated by three validators and it obtained very feasible results with an average score of 190.33 from 212. The average score of the response sheet questionnaire was 29,500 with good category and Alpha Cronbach reliability results of 0.871. Reliability of entrepreneurial interest questionnaire is 0.935. The results of this study indicate that entrepreneur interest of student influences on student learning outcomes (tcount 10.811 > ttable 1.660).
A misconception is a problem that is often encountered in the world of education caused by several things, including students' initial prejudices, incompetent teachers, unclear textbooks, different contexts of the student experience, and teaching methods that only contain lectures. This study is intended to answer the problem regarding the effectiveness of cognitive conflict-based chemistry learning in reducing students' misconceptions about acid-base material. This research is quasi-experimental research with One group Pre-test and Post-test Design. The population in this study was all class XI IPA. The sample in this study was class XI IPA I. The instrument used in this study was a student's concept understanding test. The data collection method used is a multiple-choice reasoned test method. Changes in misconceptions were analyzed descriptively and statistically. A descriptive analysis was conducted to see changes in students' concepts. Statistical analysis using the T-test. Based on the research, it was found that the indicators of questions that experienced misconceptions were: Arrhenius acid-base theory (32.05%), Arrhenius acid-base classification (56.40%), Bronsted Lowry theory (43.59%), writing down the acid-base reaction equation according to Bronsted Lowry and Lewis acid-base theory (59.00%), distinguish between Arrhenius, Bronsted Lowry and Lewis acid-base theories (49.00%), the nature of acidic and basic solutions (47.00), degree of acidity/pH (79.00%), determination of strong acid (79.00%), determination of strong base (46.00%), degree of ionization in acid and base determination (46.00%) and application of the concept of pH in pollution (66.00%). Understanding of students' initial conceptions, namely students who are classified as knowing the concept of 23.18%, misconceptions of 53.95%, and not knowing the concept of 22.87%, while the understanding of the final conception of students is students who are classified as knowing concepts of 76, 20%, a misconception of 15.49% and not knowing the concept of 8.31%. Based on these data, it can be concluded that the cognitive conflict learning method is effective in reducing students' misconceptions
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