JKPK (Jurnal Kimia dan Pendidikan Kimia)
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Implementation of Scaffolding in Project Based Learning Model to Improve Skills of Science Process in Buffer Solution Material
No full textDynamic assessment, which is supported by scaffolding, consists of questioning, prompting, cueing, and explaining. Scaffolding is considered as an effort to overcome learning problems which present in the concept of buffer solution as well as in the Project-based Learning, which aims to improve students' science process skills. This study aims to investigate the implementation of scaffolding to improve students' science process skills about the concept of buffer solution. Data were collected using in-depth interviews and analyzed using the Delphi technique. Based on the results of the analysis, it can be seen that the ideal scaffolding widely used was the questioning and the prompting. This was because the students only needed to be guided to solve the problems using the most appropriate assistance to overcome the issues. Therefore, it can be concluded that the implementation of the scaffolding was able to help the students to overcome the problems that occur during the learning process. The implementation was also able to improve the students' understanding and skills of the science process about the concept of buffer solution
Binahong Leaves Water Extract (Anredera cordifolia (Tenore) Steen.) as a Natural Foaming and Antibacterial Agent of Antiseptic Liquid Bath Soap
Get PDFThe research about the use of binahong leaves water extract (Anredera cordifolia (Tenore) Steen.) as a natural foaming and antibacterial agent in the production of antiseptic liquid bath soap has been conducted. The extraction of binahong leaves was done by the maceration method using water solvents, and then saponin identification was carried out using a foam test and Lieberman Burchard. Antiseptic liquid soap is made in 6 preparations with variations in the ratio of Sodium Lauryl Sulfate (SLS) and water extract of binahong leaves. Antibacterial activity test was carried out on Staphylococcus aureus and Escherichia coli using the excellent diffusion method. The results showed that binahong leaf water extract contained saponins and produced a stable foam of more than 10 minutes so that it could be used as a natural foaming agent in the production of antiseptic liquid bath soap. The soap produced meets the quality requirements of SNI 06-4085-1996 concerning Liquid Bath Soap, where preparation 4 has the best results with detergency power of 40%; pH 8,87; free alkali content of 0,04%; and a specific gravity of 1,06 gr/ml. A liquid bath soap with binahong leaves water extract surfactant (preparation 6) has the highest antibacterial activity against S. aureus and E. coli with inhibition area diameter of 13,5 mm (strong) and 12,5 mm (strong) respectively
Development Learning Cycle 5E Module Integrated with Science, Technology, Engineering, and Mathematics (STEM) in Thermochemistry
Get PDFThe success of the learning process is something that needs to be considered in 21st-century learning. One of the successes in teaching and learning uses appropriate learning models. One of the 21st-century learning models is the 5E Learning Cycle integrated with Science, Technology, Engineering, and Mathematics (STEM). This learning model encourages student activities in the teaching and learning process, with the encouragement of student activities, students' science process skills will grow. Science process skill is one of skill that student must have in 21st-century learning. One effort to encourage students' process skills is to use a virtual laboratory. This research aims to develop a 5E Learning Cycle module integrated with STEM and is equipped using a virtual laboratory (www.chemcollective.org) on thermochemistry material. This study's subjects were students of class XI of state high schools in the city of Kediri. This research is a Research and Development (R&D). The data collected through interview, observation, and questionnaires. The results of this study are: students need a teaching material that can drive the student achievement of the teaching and learning process in the 21st century in thermochemistry material; module validity which is declared valid by a severe expert (v = 0.89); The module developed shows effective results seen from the learning outcome on thermochemistry material and the module can foster science process skil
INFLUENCE OF TIME AND CONCENTRATION ON TEXTURAL PROPERTIES OF MESOPOROUS CARBONS OF GELATIN PREPARED BY HARD-TEMPLATING PROCESS
Get PDF Mesoporous carbons with different textural properties were prepared with gelatin by hard templating process. The effect silica removal condition (time and acid concentration) on the nanocomposite properties was studied during synthesis process. 1, 6, and 24 h silica removal times and 10%, 20%, 30% and 40% HF concentraton were chosen. Textural properties and microstructure of the nanocomposites were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDAX), and N2 adsorption– desorption. Results showed that removal silica time process led to mesoporous nucleation and growth on the surface of mesoporous carbon. At decreasing of removal silica time and HF concentration the surface area and total pore volume increased from 410 to 760 m2/g and 0.14–0.99 cm3/g with almost same of the average pore diameter considerably at 4.1 nm. Furthermore, it was observed more homogeneous pore distribution with decreasing the silica removal time dan HF consentration. In conclusion, the silica removal time and acid concentration play an important role on textural properties of mesoporous carbon which could have a major effect on adsorption properties of sulfuric compound in the fuel
QSAR Modeling of Compounds Derived from 1,2,3-Triazolopiperidine as DPP-4 Enzyme Inhibitors Using Semiempirical AM1
Get PDFThis study aims to model the derived compounds of 1,2,3-triazolopiperidine using semÂiempirical method AM1 and determine the further derivation with the better IC50 values against DPP-4 enzyme theoretically. This research employed ChemDraw Pro 12 software for for 2D strucÂtural drawing, Hyperchem 8.0 for 3D modelling, and MLR statistical analysis for modeling QSAR equations. The semiempirical method was likely to be the appropriate platform to apply because the correlation coefficient of H1 NMR chemical shift between theoretical and actual value is relaÂtively close, 0.8891. The multilinear regression analysis produced 4 equation models where the best one is equation 4 as detailed below:†IC50   = 875,5116 + (-7400,27*qH35) + (-0,00133* Eat.is) + (-3230,72* qN23) + (3,30277* µ)†n = 25; r2 = 0,594; Adjusted r2= 0,486; PRESS = 1,2× 104. Finally, the theoretically promising substituent was -CN possessing IC50 value = 1.61 nM.Â
Natural Dye from Kepok Banana Leaf Stalk on Cotton Fabric with Variation of Fixation
No full textThe purposes of this study are to apply the natural dye obtained from Musa paradisiaca Var. Balbisiana Colla leaf stalk on cotton fabric with variation of fixation. The experiment was carried out by several steps including extraction of natural dye, mordanting process, dyeing process, fixation process and testing the application of natural dye on cotton fabric. The application testing was evaluated based on the color fastness againts washing and rubbing, color changes with gray scale and color staining with stainning scale. The results of this study show that extract of natural dye from Musa paradisiaca Var. Balbisiana Colla leaf stalk is applicable as natural dye in textile. Moreover, using fixation can increase the color fastness in which alum 10 g/L provided the best color fastness, ie scale 3-4 (good enough) for color fastness againts washing and dry rubbing, and 4 (good) for wet rubbing
Gamma Irradiation for Preservation of Suruhan Herbs (Peperomia pellucida L. Kunth.) and its Bioactivity Against L1210 Leukemia Cells
Get PDFPeperomia pellucida includes the Piperaceae family that has anti-cancer, anti-inflammatory, antioxidant, and anti-microbial activities. Microbes easily contaminate dry herbs during storage, so special handling is needed. One of the preservation techniques is using irradiation technology. This technique can be used to extend the shelf life of herbal medicinal ingredients. This research aimed to study the effects of irradiation on the anti-cancer activity of P. pellucida leaves. P. pellucida leaves' dried powder was irradiated at doses of 5, 7.5, 10, and 15 kGy. The anti-cancer activity test was carried out against L1210 leukaemia cells. The un-irradiated irradiated samples were macerated successively with n-hexane, ethyl acetate, and ethanol, then be concentrated. The ethyl acetate extract was fractionated using silica gel column chromatography, obtained seven fractions. Their IC50 values < 20 mg/mL, with fraction F4 was the most active fraction (IC50 1.9 mg/mL). The result showed that gamma radiation at doses of 5 - 15 kGy reduced their cytotoxic activity significantly. However, the fractions were still in the active category as anti-cancer (IC50 values were < 20 mg/mL)
Synthesis and Characterization of Fe3O4 Composites Embeded on Coconut Shell Activated Carbon
No full textSynthesis and characterization of Fe3O4-coconut shell activated carbon composites has been carried out to create a magnetic adsorbents. Composites were synthesized using the coprecipitation reflux method by mixing a solution of Fe3+/Fe2+ iron salt (mol ratio 2:1) and suspension of activated carbon in water followed by the addition of NaOH solution. The structure, functional groups, morphology and surface area of the composites were characterized using FTIR, XRD, SEM and GSA. The magnetic properties of composites are tested by response to magnetic fields. The characterization results showed that the embedment of Fe3O4 on coconut shell activated carbon was successfully carried out through the interaction of hydroxyl groups at wave numbers 601.79 and 416.62 cm-1. Diffraction peaks at 2θ 30.12° [220], 35.58° [311], 43.14° [400], 53.57° [422], 57.18° [511] and 62.83° [440] indicate the existence magnetite sized of 11.72 nm. Activated carbon has an average pore size of micropores with an average pore of 1.46 nm. Magnetite embedment reduced the surface area of activated carbon from 91.16 m2/g to 12.04 m2/g. The response of sample to the magnetic field indicates that composite has magnetic properties
The Antimicrobial and Antioxidant Activity of Endophytic Fungi Extract Associated with Chlorantus officinalis Blume and Staurogyne elongata Kuntze
Get PDFAn endophytic fungi has been widely known for a source of bioactive compounds attributed as antimicrobial and antioxidant. In this report, we investigated the antimicrobial and antioxidant activity of extract of endophytic fungi associated with two indigenous Indonesian medicinal plants, i.e., Chloranthus officinalis (CO) and Staurogyne elongata (SE). Ten endophytic fungi isolates were collected from barks, roots, and leaves of CO and SE host plants and were cultured into potato dextrose broth (PDB) media. After 14 days of incubation, the whole culture was extracted by ethyl acetate. The qualitative antimicrobial analysis that was conducted by dot blot and TLC-bioautography showed all of the extracts show antimicrobial activity against Staphylococcus aureus. At the same time, they were observed less active against Escherichia coli. The minimum inhibitory concentration (MIC) analysis showed that endophytic fungi extract of CO2 and SE3 are classified as strong antibacterial activity against S. aureus with MIC value <8 µg/ml. The TLC bioautography of antioxidant displayed the appearance of radical inhibition area from SE4 and SE5 extract. Quantitative antioxidant activity, which was conducted by the radical DPPH scavenging, showed that SE5 has the lowest IC50 value, i.e., 56.3679 µg/ml (AAI value 0.5455) and was classified as moderate antioxidant activity. Meanwhile, the remaining extracts are classified as weak antioxidant activity
The Development of Scaffolding in Inquiry-Based Learning to Improve Students' Science Process Skills in The Concept of Acid and Base Solution
Get PDFThe technique of providing learning support in a structured manner to encourage students to learn independently is called scaffolding. This consists of four types questioning, prompting, cueing, and explaining. This study aims to describe the procedure for developing scaffolding in inquiry-based learning that is beneficial to improve students' science process skills in the concept of acid and base solution. The heuristic method in the type of F2-O3-S1+S5+S6-A3 was used in this study to develop the design of the scaffolding. The data were collected using an interview and analyzed using a Delphi technique. Based on the expert validation, it was seen that the scaffolding technique designed was suitable for use. The results of the student trial also showed that the scaffolding technique was effective to be used to improve students' science process skills. It can be concluded that the scaffolding technique on inquiry-based learning was able to improve students' science process skills in the concept of acid and base solution