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Porcine pepsin is the main protease composed in collagen production in many needs. One alternative offered is replacing porcine based on protease produced by bacteria. Bacillus megaterium TR-10 was chosen in this study as the proteolytic bacterium because the collagen extraction used its crude extract of protease was claimed halal and non-pathogenic. The aim of this study was to meticulously identify the incubation time, the content of waste tofu as the N source, and pH level for optimizing production of crude extract of protease from Bacillus megaterium TR-10. The final result for the optimum crude extract of protease was 7,426 U/mL from Bacillus megaterium TR-10 produced by inoculating of 20 mL inoculum at the exponential phase in 100 mL of production medium containing 115 mg protein of tofu liquid waste at pH 7 and incubated for 43 hours at 37° C. [ABSTRACT FROM AUTHOR]

This study aims to determine the effect of the LC 5E-TPS learning model on students' high-order thinking skills (HOTS) on the reaction rate subject. The research design used was quasi-experimental with a one-group pretest-posttest design. The subject of this research is class XI Senior High School in Malang, Indonesia. Subjects consisted of three classes taught with different learning models, namely the LC 5E-TPS learning model, LC 5E learning model, and conventional methods. The instrument used is a cognitive learning outcome test based on high-order thinking skills (HOTS) which consists of 15 questions (reliability 0.805). The research data were analyzed using statistical analysis including the One Way ANOVA test, Paired Sample T-Test, N-Gain Score, and d-effect size Cohen's test. The results showed that: (1) the LC 5E-TPS learning model affected students' high-order thinking skills. The average HOTS test score for the LC 5E-TPS class (75.90) is higher than the LC 5E class (57.76) and the conventional class (47.63); (2) the LC 5E-TPS model is more effective in increasing students' HOTS compared to the LC 5E model and conventional methods with d-effect size Cohen results in LC 5E-TPS (3.83), LC 5E (2.53), and conventional (1,70). [ABSTRACT FROM AUTHOR]

High salt-tolerant extracellular protease is an enzyme that plays a crucial role in industries and requires high salt conditions. Some protease enzymes are not resistant to high salt conditions because they may denature under high salt concentrations. Halophilic microbes produce extracellular enzymes that are stable at high salts. This research has succeeded isolating several halophilic microbes capable of producing extracellular proteases from Bledug Kuwu, Grobogan, Central Java, Indonesia. Extracellular proteases producing bacteria screened with skim milk selective medium and purified with the quadrant streak method. Then, the pure isolate and the resulting extracellular protease were characterized BK1B isolate was a Gram-positive bacterium, while BK1D was a Gram-negative bacterium. BK1B isolate is a halotolerant bacterium and BK1D is a moderate halophilic bacterium. BK1B and BK1D had the largest proteolytic index values, capable of producing extracellular proteases with an optimal production time of three days and pH 6. Extracellular proteases from BK1B and BK1D worked optimally at pH 6 and temperatures of 45 and 42 °C with 2.541 and 3.505 U/mL activity and resistance to NaCl concentrations ranging from 3 - 13% NaCl. This suggests that extracellular proteases from BK1B and BK1D strains can be stable at high salt concentrations. [ABSTRACT FROM AUTHOR]

Gout and COVID-19 have been of global concerns. One of the drugs for gout is allopurinol that acts as a xanthin oxidase inhibitor (XOI). However, this drug has side effects, so we need safer drugs from herbal sources such as sugar apple. Sugar apple ethanol extract can act as XOI, but the activity of steeping with hot water is not known. Besides, several sugar apple compounds are also reported to be active as anti-viruses, but their activity has not been categorized against the COVID-19. This study aimed at making powder from sugar apple, which was brew using hot water, determined the phytochemical content, including TPC and TFC, tested its activity as XOI and the profile bond of the active compounds to the S protein of COVID-19. The results showed that the extract of sugar apple powder contained alkaloids, flavonoids, polyphenols, with TPC and TFC levels of 0.048% and 0.099%, active as XOI. Furthermore, the in silico analysis has shown three compounds in sugar apple, namely quercetin-3-glucoside, rutin, and kaempferol-3-rutinoside that can bound to the RBD of S protein of COVID-19, so it is predicted that the three compounds have anti-COVID-19 activity. [ABSTRACT FROM AUTHOR]

The discovery of DNA structure has changed our understanding of life. Large data has been generated from researches triggered by this discovery. Information technology development has made it possible to share DNA sequences, proteins sequences, and 3D structure of proteins, articles, and tools. This information will be continuously produced. Consequently, it will result in dynamic databases. As an agent of sustainability change, university is forced to make continuous adjustments to this dynamic phenomenon. This paper reports our preliminary study on developing a learning model to promote life-based learning to prepare our students to live in such dynamic and rapidly changing environments. This study focuses on utilizing open-access databases as learning resources by final year students to construct their knowledge on biochemistry and biotechnology through the final year project. The research was done by overviewing students' scripts and gathering information from students carrying the final year project using a closed- ended questionnaire. The results showed deficient students' access to the open-access databases by students who worked on protein projects due to low awareness of the presence of such databases. We propose problem-based learning with a database digging learning model as a possible learning model to promote students awareness at early courses [ABSTRACT FROM AUTHOR]

The damage of natural equilibrium nowadays requires urgent action. All global changes we face are the forms of self-reorganization process in nature. The long history of chemistry creates the means for overpowering nature for natural resources exploitation, for the sake of humankind. Chemistry is one of the key sciences to understand natural changes. Some probes in analytical chemistry can be the key information about the whole phenomena. Method development and validations in analytical chemistry must be in line with the need to preserve nature. This way technology must have good intension to assess its process and its risk management. Moreover, the power of big data can aid the need for chemists to examine earth condition as well as global common problems. In this paper, a rough survey about ethical issues regarding chemistry and its impact on the environment is reported. Ethics development in chemistry education needs to be put into action, from the very beginning of the knowledge transfer. An eco-reflexive chemistry education must be based also on chemist's responsibility towards nature as a whole. [ABSTRACT FROM AUTHOR]

Bioplastics became important as oil-based plastic accumulated around the world and polluted the environment. keratin is existed in chicken feathers around 90%. Keratin is an important biomaterial and the most inexpensive abundant biomaterial. Previous study showed that solid-state fermentation of keratinase by bacillus sp. MD24 using chicken feathers a sole carbon and nitrogen source produced soluble keratin hydrolysate. The keratin hydrolysate can be transformed into keratin biofilm which ultimately might be used to make bioplastic. However keratin biofilm has poor mechanical properties. Blending keratin with other biomaterial such as carrageenan might improve keratin biofilm properties. This research aimed to make keratin-carrageenan polyblend and characterize the properties of the polyblend. Keratin hydrolysate was collected from keratinase solid-state fermentation liquid by-product. After dyalisis, soluble keratin was mixed with carrageenan solution at various mass ratio. Prior to mix with carrageenan, Particle size analyzer (PSA) is used to examined the size of soluble keratin. The polybend film was then analyzed using FTIR, SEM, and DMA. SEM photograph showed morphology of film surface which smooth and homogen. FTIR spectra showed the presence of both carrageenan-keratin in the film. DMA shows better mechanical properties of polyblend film. [ABSTRACT FROM AUTHOR]

Keratinase is an alternative material used in the dehairing process of leather tanning industry to minimise production of hazardous waste. In the preservation process, leather soaked in high salt content solution, thus high salt tolerant keratinase is needed in this industry. By using halophilic bacteria isolated from the Bledug Kuwu mud crater, the BK-1H isolate is expected to have keratinase activity that can be used in the dehairing process of leather tanning. Isolate BK-1H used in this research refer to previous research that shown the high proteolitic index. The isolate needed to be identified for their ability to produce enzymes. The research stage include : (1) Gram staining and observation of bacterial colony morphology, (2) characterization of proteases by determining the optimum pH and temperature of the enzyme, and knowing the effect of metal addition on enzyme activity, (3) the variation effect of pH, time, and humidity to enzymes activity, (4) the ability of bacteria to degrade chicken feathers, (5) the ability of enzymes to degrade chicken feathers, and (6) genotypic identification of isolates using 16S rRNA gene sequencing. BK-1H was identified as a rod-shaped Gram-negative bacteria. Protease produced by BK-1H showed a maximum activity of 4,083 U/mL at 46 °C. The highest activity value for pH optimum is 1.308 (±0.243) U/mL, at pH 7. The addition of metal ions Zn2+, Ca2+, Co2+, and Mg2+ decrease enzymes their activity so that further testing is needed for other metal ions. The effect of variations pH at the time of enzyme production showed the highest yield at pH 10 with the optimum time of enzyme production within 2 days. The results of the sequencing showed the relations between BK-1H to Bacillus swezeyi with an identity percentage of 98.51%. [ABSTRACT FROM AUTHOR]

Keratin is a high-potential biopolymer as raw material for bioplastic to overcome environmental problems due to plastic waste. In this research, keratin was extracted from chicken feathers using the acid method. Extract keratin was blended with carboxymethyl cellulose (CMC) and various amount of glycerol as a plasticizer to produce bioplastics. Analysis of mechanical properties and surface morphology was used to determine the best synthesis result. The best bioplastic was produced from the ratio of 5/1 for CMC/keratin with 25% w/w of glycerol. These keratin-based bioplastics might be further studied as an eco-friendly biomaterial for further application. [ABSTRACT FROM AUTHOR]

During the roasting of coffee beans, some essential oils are produced. Roasted arabica coffee essential oil is rarely used. Essential coffee oil brings coffee's aroma. This study aims to analyse the profile of Arabica coffee essential oil produced during roasting at around 210 and 230 ˚C. The oil was collected from the surface of roasted beans and the roaster before dissolving it in n-hexane solvent. This solution was analysed using GC-MS and FTIR methods. The results revealed several profiles of compounds: alkanes, cycloalkanes, haloalkanes, aldehydes, ketones, alcohols, esters, and aromatic hydrocarbons, which are explained by the appearance of related functional groups in the FTIR spectra. Better processing is also recommended to obtain essential coffee oil during roasting. In this case, essential coffee oil would benefit some industries. [ABSTRACT FROM AUTHOR]

Keratinase is a specific proteolytic enzyme that degrades keratin. Keratinase has wide applications in global industries. Bacillus sp. MD24 has been reported to produce keratinase by solid-state fermentation method using chicken feathers as a sole substrate. Furthermore, keratinase production could be elevated by adding biomass waste (sugarcane bagasse, tofu waste, or rice husk) to chicken feathers. However, the ratio of biomass waste addition was unknown. The liquid by-product of keratinase production contains both carbon and nitrogen sources, which is potential as organic fertilizer. This study aimed to determine the effect of chicken feathers and an additional carbon source ratio toward keratinase production by Bacillus sp. MD24 and potential of its liquid by-products as organic fertilizer. This research was conducted in several stages: keratinase production, enzyme assay, testing liquid by-product on the growth of caisim, and plant morphological analysis. The results showed that the addition of tofu waste produced higher keratinase compared to other carbon sources. The optimal ratio between chicken feathers and tofu waste to produce optimal keratinase was 1:0,4 on the 6th day. Growth rates, the number of leaves, and chlorophyll a and b pigments increased significantly with 20-days irrigation at 1:5 and 1:10 (v/v) dilution. [ABSTRACT FROM AUTHOR]

Obesity is caused by fat accumulation resulting from the low performance of pancreatic lipase enzyme, while gout is caused by the increase of uric acid in the blood due to the imbalanced production and excretion of uric acid. These diseases can be maintained by reducing foods containing high purines (gout), high carbohydrates and fats (obesity). Orlistat is a synthetic drug which is used to reduce excess fat in the body to inhibit pancreatic lipase enzyme, while allopurinol is synthetic drug used to reduce uric acid levels by inhibiting xanthine oxidase enzyme. Both synthetic drugs have several negative side effects on health, therefore, it is urgent to find out natural medicine which has minimum negative effects. There are several steps in this research design includes preparations of sugar apple and watermelon mesocarp; characterization using SEM-EDX; qualitative phytochemicals test; investigate the inhibitory relative of sugar apples to one tablet orlistat; and investigate the inhibitory relative of watermelon mesocarp to one tablet allopurinol. The results showed that the percentage yield of sugar apple was 8.18% and the percentage yield of watermelon mesocarp was 2.46%. Characterizations with SEM showed that average of particles diameter of sugar apple powder and watermelon mesocarp were 20.167 µm and 17.236 µm. The EDX analysis showed that sugar apple contains element K (0,60%) while watermelon mesocarp has several minerals: Mg (0.47%), Al (0.33%), P (0.60%), Cl (0.79%), K (3.02%), and Ca (0.39%). Both brewed sugar apple and watermelon mesocarp contain secondary metabolites flavonoid and polyphenol. The inhibition activity of brewed 1.5 g/150 mL sugar apple to pancreatic lipase enzyme was 18.05% while the inhibition activity of brewed 1.5 g/150 mL watermelon mesocarp to xanthine oxidase was 19.75%. Therefore, it can be concluded that extracts of sugar apple and watermelon mesocarp have potency as natural drugs with double benefit as anti-obesity and anti-gout. [ABSTRACT FROM AUTHOR]

Keratin in chicken feathers has potential as a raw material for wood adhesives because it has functional groups from amino acid side chains that are able to cross-link with lignin in wood. The solid structure of keratin in chicken feathers needs to be converted into a soluble structure through a degradation step in order to be applied as a wood adhesive. Chemical degradation of keratin in chicken feathers cannot control the results of hydrolysis which causes keratin to be degraded into amino acids and produces hazardous chemical waste. Enzymatic degradation is an environmentally friendly alternative. Previous research reported that Bacillus sp. MD24 and 2 microbial isolates from Pasuruan salt pond water, namely TG3 and TG6 isolates were able to produce keratinase. Keratinase from each microbe is thought to have the ability to degrade by cutting at different specific keratin sites. Thus, the microbial consortium may be able to increase the concentration of soluble keratin hydrolyzate with more diverse molecular weights. This research was conducted with an experimental laboratory design. The steps carried out in this study include: (1) Confirming the ability of TG3 and TG6 isolates to produce keratinase; (2) Identification of TG3 and TG6 isolate species using 16s rRNA genomic methods; (3) Optimization of the humidity of the fermentation medium for TG3 and TG6 isolates; (4) Trial of microbial consortium isolates TG3 and TG6 with Bacillus sp. MD24 in keratinase fermentation. The environmental conditions of keratinase fermentation were carried out at 37°C and pH 8 using the Solid-State Fermentation method. TG3 and TG6 isolates have been tested for their ability to produce keratinase seen from their ability to degrade keratin in chicken feathers as much as 11.20% and 14.50% for 2 days of incubation, respectively. Species identification of isolates TG3 and TG6 showed that they were closely related to Salinivibrio proteolyticus with a similarity percentage of 99.13% and 99.14%, respectively. The optimization of the humidity of the fermentation medium showed that on the third day of incubation, both showed the highest optimum activity at variations in the ratio of chicken feather weight (g): volume of salt solution pH 8 (mL) 1:3. In this study, the microbial consortium of Bacillus sp MD24 with isolates TG3 and TG6 was not able to significantly increase the degradation ability of chicken feathers and the protein content of keratin hydrolyzate. This is possibly because the characteristics of the optimum pH and temperature of the enzymes produced by each microbe are different, so that in the microbial consortium it is necessary to select 2 isolates of microbes that have almost the same optimum characteristics of enzymes. [ABSTRACT FROM AUTHOR]

Cellulose-based bioplastics have been developed to reduce the use of synthetic plastics. In this work, a renewable material, cellulose-cysteine was synthesized using the esterification method to improve mechanical properties by adding disulfide bonds therein. Avicel PH101 and PH102 were used as raw materials for the manufacture of cellulose-cysteine. The SEM-EDX analysis showed that cysteine was successfully grafted with 1.44-1.72% on sulfur element content with a rougher surface structure than avicel. The FT-IR peak at 1749 cm-1 and 1429 cm-1 showed the presence of C=O esters and N-H groups of cysteine, respectively. Thus, it was confirmed that cysteine has bound to cellulose. [ABSTRACT FROM AUTHOR]

The abundance of non-biodegradable plastic waste in the environment has concerned the world since its mass production in the 1950s. On the other hand, the same problem happened to biomass waste, i.e., poultry feathers. In this work, keratin extracted from chicken feathers by acid hydrolysis was blended with microcrystalline cellulose, polyvinyl alcohol (PVA), and glycerol to form bioplastic via solution casting. Keratin and cellulose ratios of 4:0, 3:1, 2:2, 1:3, and 0:4 were blended with PVA dan glycerol. Their mechanical strength, thermal character, and degradability properties were observed. Adding keratin to cellulose lowering tensile strength but increasing biodegradability, while the best thermal property was achieved at keratin:cellulose ratio of 2:2. The result showed that keratin-based bioplastic has a high potential for further development to become high-functioning bioplastics. [ABSTRACT FROM AUTHOR]

Coffee's volatiles was extracted and adsorbed in a silica cellulose matrix. Silica from rice husk ash and cellulose from nata de coco was made adsorbent, from which volatile compounds can be adsorbed and released. Extracts from Arabica coffee types were applied. The objectives were to make an environment-friendly air freshener from coffee extracts and silica cellulose materials. GC-MS was employed to determine the volatiles released at 1st, 2nd, 7th and 14th days of adsorption time. The results showed interesting profiles of Arabica coffee with organic acid and ester components. A study about the surface dynamics of certain volatiles is underway. [ABSTRACT FROM AUTHOR]

Zn-oleate and Al-oleate are fatty acid metal salts known as synthetic metal soaps. These substances are not surface-active agents and therefore cannot function as cleaning agents. Concerning their structure, it can be thought to absorbed UV radiation and potentially use as a chemical sunscreen. Our study focused on synthesize metal (zinc and aluminum) oleate and sunscreen activity assay. The metal oleate synthesis was carried out using the trans-esterification method from the as-synthesized sodium oleate. Physicochemical properties of the as-synthesized zinc oleate and aluminum oleate were characterized using XRF, FT-IR, XRD, and SPF-based sunscreen activity assay by UV-spectrophotometry. The as-synthesized metal oleate resulted in the distinguishing feature. The as-synthesized zinc oleate is a white solid powder, melting point 64-71 °C, soluble in benzene, varnish oil, chloroform, and methanol, but un-soluble in water, ethanol, octanol, and petroleum ether. The as-synthesized aluminum oleate decomposed at 120 °C then its solubility properties are similar the as-synthesized zinc oleate. Zinc oleate is active as sunscreen (SPF 2.78), while aluminum oleate is inactive as sunscreen (SPF 0.96). [ABSTRACT FROM AUTHOR]

Modern civilization is always correlated with higher energy demand. Science development also brings possibilities of energy preservation along with the realization of the shortage of fossil fuel. Scientists are working for alternative energy resources and new materials for energy storage and transformations. More materials related to energy are emerging, along with new methods developed and validated to justify the applications and capabilities. However, the side effect of this sort of activity is not well considered so far. It becomes the background of environmental problems today. Chemistry as fundamental science plays a significant role in changing natural resources and shifting the natural equilibrium in our environment. Deep consideration based on previous reports was done by the literature review method. In this case, ethics in science might become very important to be implemented from the perspective of chemists and science as early as possible. At the same time, chemistry education can also display its role in describing a minute change in molecular level and its impact on the whole nature in the long run. Daily life attitude and wiser urban management, in turn, affect balancing small scale life web and preserving nature and energy for the common good for the whole world and community. A better scientific view of our environment as reported and reviewed is the crucial attitude of human beings as a part of nature. [ABSTRACT FROM AUTHOR]

Keratin is a protein that is very difficult to break down. One of the ways to degrade keratin is enzymatic degradation using keratinase. Keratinase plays an important role in the leather tanning industry, so it is necessary to explore keratinase-producing microbes. This study used isolate GAM15 from the peat soil of Palangka Raya, Central Kalimantan. The research stages were rejuvenation of protease-producing microbes, determination of isolate purity and identification of phenotypic morphology of isolates, a test of ability to degrade chicken feathers, determination of keratinase character, optimization of keratinase production using chicken feather substrate, and genotypic identification. The optimum GAM15 keratinase at pH 6, temperature 43 C, and the addition of Mg2+ and Ca2+ ions had no effect on keratinase activity. Optimal keratinase production was optimized on the second day and media at pH 5 with an activity value of 7,829 U/mL. In determining the moisture ratio, the keratinase activity was 9.079 U/mL with a mass of chicken feather substrate and a volume of saline solution at a humidity of 1:3. The percent weight loss after optimization is 12.9%. GAM15 isolate is a type of microbe that already exists and has a similarity percentage of 100.00% to the Bacillus proteolytic strain MCCC 1A00365 species. [ABSTRACT FROM AUTHOR]

Keratinase plays an important role in the leather tanning industry. The industry requires enzymes that are stable in a high salt environment process. One source of those enzymes is microbes that live in salt ponds. Previously, 8 halophilic isolates were isolated from Pasuruan salt pond. TG-3 and TG-6 have been characterized and tested for their ability to produce keratinase using chicken feathers with the highest activity of 5.893 U/mL and 9.685 U/mL. In this study, TG-5 isolate was characterized and tested for its ability to produce keratinase. The results exhibited the TG-5 isolate was Gram- negative with a rode shape and was not a new type of microbe because the sensitivity to the Salinivibrio proteolyticus strain DV was above 97%, which was 99.20%, and it was called Salinivibrio proteolyticus TG5. The optimum activity of TG-5 keratinase was achieved at pH 8, temperature 43 °C, 5% NaCl, and the presence of 1 mM Mg2+ ions. Optimization of keratinase production by SSF method showed day 3 of incubation, at pH 7, and humidity ratio of 1:4 (chicken feather: salt solution) with enzyme activity value of 6.094 U/mL. The results indicate that salinivibrio proteolyticcus TG-5 has potential in tanning leather. [ABSTRACT FROM AUTHOR]

Protease is one of the industrial enzymes which is capable of hydrolyzing peptide bonds in proteins. Many industries often require protease that is tolerant at high salt concentration. Indonesia is a country that has high microbial biodiversity, including halophiles, which naturally live in high salt environments such as salt concentrating ponds. We investigated proteases produced by halophilic microbes isolated from salt concentrating pond at Pasuruan, East Java. This research was conducted in several stages, namely isolation and selection of bacteria, gram staining and homogeneity tests, the stability of isolated bacteria at various NaCl concentrations, determination of optimal protease production time, characterization of proteases by pH, temperature, and the effect of salt concentration. The result shows that six isolates were obtained from salt concentrating pond at the highest concentration of 8.4%. No colonies grew from saltwater at higher salt concentrations. All colonies were indicated as rod-shaped gram-negative bacteria. Two of the isolates, namely TG-6 and TG-3, were selected for further investigation due to their high proteolytic index. The selected isolates show the highest production time of 3 days at 43 °C, optimum pH of 8 and 9, and crude extract activity of 2.475 and 4.809 U/mL, respectively. They grow at a moderate salt concentration (up to 10% of NaCl), and the enzyme has the potential for industrial application. [ABSTRACT FROM AUTHOR]

Diabetes Mellitus (DM) and COVID-19 diseases are still global problems. One of the causes of DM, mainly type 2 is unhealthy eating habits, including white sugar, which contains almost no active compounds except sucrose. The active compounds in sugarcane juice such as ferulic acid, gallic acid, 4-Hydroxy benzoate acid, and vanillic acid, which are suspected besides alpha-amylase inhibitors, also have potential as anti COVID-19. The purpose of this research is to extract secondary metabolites from sugarcane juice, determine TPC and TFC, and to know in silico activity of the active compounds in sugarcane juice as an alpha-amylase inhibitor and binding position to the active site of the spike protein. The results have shown that TPC and TFC in sugarcane juice are 0.5501% and 0.4480%. The in silico analysis has proven that the ferulic acid compound is bonded to the alpha-amylase binding site as acarbose did. Gallic acid, 4-hydroxy benzoic acid, and vanillic acid compounds are bonded to RBD of S protein COVID-19 as chloroquine did, with various binding affinity. These results indicate that phenolic and flavonoids in sugarcane juice have the potential as an alpha-amylase inhibitor and anti COVID-19. [ABSTRACT FROM AUTHOR]

POGIL had been shown to be one superior learning model in science education including chemistry education and it match with mandatory learning approach in current Indonesian High school curriculum. The effect of POGIL in learning result was somehow vary in many studied. One problem found in our observation, students were not able to apply their new knowledge at application step of POGIL model. This paper reports our effort to improve student’s cognitive learning outcome in learning buffer solution by modifying POGIL at application step. Buffer solution is one part of chemistry at high school of which students had difficulties in understanding it. In learning buffer, it requires ability in conceptual understanding and algorithmic problem solving. Polya’s problem solving method has known as one powerful problem solving model in mathematics. We had modified POGIL by incorporating Polya’s problem solving steps at application step of POGIL and implemented the model in learning buffer solution. Although only 50% student passed the school passing grade in experimental class, the modified model seem superior compared to original POGIL. In control class only 16% students passed the school passing grade. The mean rank value in the Mann-Whitney test in the experimental class (46.61) was higher than the control class (26.39). Therefore, modified POGIL was proven to be better model in learning buffer solution. This study was done in a short period of learning buffer solution. In order to get higher cognitive outcome in learning chemistry, longer observation must be carried out until students accustom with the modified POGIL. [ABSTRACT FROM AUTHOR]

Buffer solution is one difficult topic in high school chemistry. POGIL has known as one powerful model in teaching chemistry; however, after learning chemistry under POGIL environment we observed students were still having difficulties in implementing their new knowledge to solve problems. We did a study as our effort to improve student capability in solving problem related to buffer solution by modifying POGIL with Polya’s problem solving steps at the application step. Unlike common tests such as multiple choices and free descriptive tests, we apply Puvirajah’s argumentation skills test to justify student’s knowledge after learning process. Although modified POGIL gave better results compared to the original POGIL, the results revealed that original POGIL, as well as modified POGIL, did not succeed in building scientific argumentation skills. They were both still at insufficient to basic level of Puvirajah’s argumentation quality. The result was not surprising since student in both experiment and control classes were not used to learn under POGIL environment and the introduction to POGIL was done in a very short period. In addition, students were never introduced in argumentation skills test. Modified POGIL and argumentation skills test has to be implemented for much longer period to build to see the effect of the model to argumentation skills. [ABSTRACT FROM AUTHOR]