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Despite apoptosis processes being conserved, cancer cells have developed mechanisms to inhibit apoptosis by altering anti-apoptotic molecules or inactivating pro-apoptotic. The aim of this study was to determine the palmitic acid of Musa paradisiaca var. sapientum (L) Kunz (MP) stem extracts against human oral squamous cell carcinoma (hOSCC) through caspase-3.Ethanol and ethyl acetate extracts of MP stem were analyzed by gas chromatography-mass spectrometry (GC-MS). Computerized models of chemically active compounds were used to predict anticancer activity. Cytotoxicity was evaluated in Artemia salina Leach and hOSCC (OM-1) culture at concentrations 100, 90, 80, 70, 60, 50, 40, 30, 20, and 10 µg/mL respectively. The expression level of caspase-3 on hOSCC was measured by enzyme-linked immunoassay (ELISA).We found seven chemically active compounds in the ethanol extract and 15 compounds in the ethyl acetate extract of MP stem. The major component was hexadecanoic acid of palmitic acid derivates, and this was predicted to have anticancer activities as apoptosis through caspase-3 stimulants. However, cytotoxicity effects against hOSCC culture were assessed by values of the 50% inhibitory concentration (IC50) of 15.00 µg/mL for the ethanol extract, and an IC50 of 10.61 µg/mL for the ethyl acetate. There was a significant increase of caspase-3 level on treatment groups compared to control.Hexadecanoic acid of MP stem extracts has anticancer activity by inhibiting cell growth of hOSCC culture through caspase-3 stimulants.

Starch is a unique polysaccharide that is widely used as a thickener, filler, and gelling agent. Indonesia is one of the largest, sweet potato producers that can be used as a source of starch. Not much is known from the utilization of sweet potato starch because of its less popularity compared to potato or cassava starch. Besides, sweet potato starch in its native state has various disadvantages such as low solubility, low stability, and high retrograde tendency. These starch limitations can be overcome by modifying the starch. Starch pregelatinization is a physical modification method carried out by heating the starch above its gelatinization temperature. This research was aimed to optimize the temperature and time of sweet potato starch pre-gelatinization. The response surface method (RSM) with a central composite design (CCD) was used to create a process model. The use of 59.53°C for 15.00 mins showed that had the most optimum characteristics in solubility, swelling power, and water-binding capacity. SEM analysis also showed that starch had larger starch granules and some granules had melted which shows that partial pre-gelatinization had occurred.

Cabang kayu mangrove merupakan limbah kayu yang bisa dimanfaatkan untuk berbagai produk kerajinan kayu. Tujuan dari kegiatan pelatihan yang dilakukan adalah melatih masyarakat membuat kerajinan berbahan cabang kayu mangrove dan memberikan pengetahuan tentang sifat-sifat dasar cabang kayu dalam pengolahannya. Metode pelatihan meliputi pemberian materi pelatihan, praktek langsung pembuatan kerajinan dan diskusi. Hasil pelatihan dari praktek tiap-tiap kelompok membuat kerajinan dari cabang kayu mangrove yang berbeda-beda, antara lainn aneka gantungan kunci, cup lampu dan tongkat kayu. Setelah pelatihan peserta bertambah pengetahuan tentang sifat-sifat dasar cabang kayu dan produk-produk kerajinan yang dibuat dari cabang kayu.

Ranting kayu mangrove sampai saat ini merupakan limbah yang belum termanfaatkan. Limbah ranting ini sangat potensial untuk dimanfaatkan sebagai bahan baku kerajinan. Tujuan dari kegiatan pelatihan ini adalah melatih masyarakat tentang pembuatan kerajinan berbahan ranting kayu mangrove dan memberikan pengetahuan tentang sifat-sifat pengerjaan kayu khususnya ranting sebagai bahan baku kerajinan. Metode pelatihan meliputi pemberian kuisioner dan materi pelatihan, diskusi dan praktek langsung pembuatan kerajinan. Hasil pelatihan dari praktek masyarakat membuat kerajinan dari ranting kayu mangrove antara lain pas bunga, bonsai, miniatur saung, miniatur kursi dan tempat tissue. Pelatihan ini merupakan pelatihan pertama yang diikuti oleh peserta terkait pelatihan pembuatan kerajinan. Peserta pelatihan mendapatkan pengetahuan tentang sifat-sifat pengerjaan kayu dan produk-produk kerajinan berbahan ranting kayu. Dampak dari kegiatan ini adalah masyarakat menjadi terampil membuat kerajinan berbahan ranting kayu mangrove.

Medan is the capital city of North Sumatra Province and the biggest city on the island of Sumatra. Big cities in Indonesia generally have problems with environmental degradation. One of the efforts to preserve the environment in urban areas is to provide public green spaces dominated by trees. In the process of its life, the tree experiences many disturbances and interventions from the surrounding environment. It can make it grow abnormally or become sick. One of the negative impacts of this is when extreme weather occurs and causes trees to break easily, fall, and fall on whatever is underneath. It can cause various material losses and even fatalities. The research has conducted at Beringin Park in Medan. It is one of the favorite places for people to gather and enjoy the freshness of clean air. Research on tree health surveys and inventories in public green spaces is important to do as one of the efforts to mitigate the occurrence of fallen tree disasters. This research is aimed to take an inventory of tree health in Beringin Park as an mitigation effort of the fallen tree disaster in Medan. Vegetation parameters were collected by using the census method at the pole and tree stage. The Shannon – Wienner diversity index has used to assess the biodiversity level of the research location. Then damage level index was analyzed by using Forest Health Monitoring Method. The results showed that the tree vegetation in Beringin Park was in the healthy category based on the Tree Damage Index Value which ranged from 1.20 to 4.10.

Vegetation is an important component of preventing erosion and drought, regulating water and hydrology, improving soil physical, chemical, and biological properties, balancing the carbon dioxide and oxygen in the air, conserving biodiversity, effecting other biota in ecosystem, and supporting the ecotourism potential. The effect varies depending on the structure and composition of the plants that comprise the area's vegetation formation. Sibolangit tourism park, with an area of 24.85 Ha, was established in 1980 by Minister of Agriculture Decree No. 636/Kpts/Um/1980. This study aims to examine the importance value index and diversity index of species in the Sibolangit tourism park area. The data was sampled using a simple random sampling method with a 5% sampling intensity. The observation plots were randomly placed to cover all the study sites. Species, diameter, height, and the number of each individual were recorded during field observation. The study recorded a total of 67 species in Sibolangit Tourism Park. The dominant species at the tree stage was Pterocarpus indicus with an IVI of 28%. Mitrephora obtusa was the dominant species at the pole and sapling stages with the IVI of 52% and 35%, respectively. At the seedling stage, Strombosia ceylanica was the dominant with an IVI of 62%. The vegetation diversity at the study site was in the moderate range with the 2.71 of Shannon-Wiener diversity index.

The mangrove forests in Indonesia are starting to decrease over time because there is still a lack of knowledge among people around the coast about the importance of mangroves. Kampung Nelayan, Medan Belawaan, is a coastal community area whose life is very dependent on coastal, mangrove, and water resources. Unmanned Aerial Vehicle (UAV) technology has the potential to provide a fast, cost-effective, and efficient mangrove mapping technique. It is very useful because mangrove areas are located in remote areas, where field measurements are difficult, time-consuming, and expensive. The objective of this study is to analyze mangrove species using UAV imagery with Object-Based Image Analysis (OBIA) classification. The object-based classification result for the overall accuracy is 82.94% where there are 7 classes of mangrove species based on the classification process, including: Avicennia alba, Avicennia officinialis, Avicennia Marina, Rhizopora apiculata, Nypah fruticans, Scyphipora hydrophylacea, Bruguiera gymnorriza. There are also two classes for non-mangrove, consisting of the water body and non-mangrove. The largest area of mangrove species in the research site is Avicennia Marina with a percentage of 33.86% covering an area of 7.80 Ha. The second-largest mangrove species with a percentage of 21.88% is Avicennia officinalis with an area of 5.04 Ha.

The jeruju plant (Acanthus ilicifolius) is a plant that is affected by the tides and usually gets a higher supply of fresh water. Jeruju plants can be processed into processed products in the form of mangrove tea. This study aims to determine the antioxidant activity and analysis of microbial contamination of ready-to-drink jeruju leaf tea based on storage time. Determination of antioxidant activity was carried out by the 2,2-diphenylpicrylhdrazyl (DPPH) method using UV-Visible Spectrophotometry. The microbiological analysis test was carried out based on the Coliform Most Probable Number (MPN). The results of the antioxidant activity test have different antioxidant activity values at each storage time. The results of microbiological analysis testing with a storage period of 3 months contain coliform bacteria, so they are not suitable for consumption.

Panthera tigris sumatraeis one of endemic species of Sumatera Island included in the endangered species red list by the IUCN. The efforts to preserve the sumatran tiger is with conservation activities both in-situ and ex-situ. One form of ex-situ conservation is to keep animals in the zoos. This study aims to assess the welfare level of Sumatran tigers are in Medan Zoo and Siantar Zoo. Aspects of tiger welfare are measured through 5 variables basedon five animal freedom, namely the free of hunger and thirst, the free of environmental discomfort, the free of pain, wounds and diseases, the free of natural behavior and the free of fear and suffering. Data collection through direct observation of animal management and assessment of minimum animal welfare standards. Interviews with veterinarians and animal keepers about human resources and management activities carried out in supporting animal welfare. The assessment is carried out by the management, namely veterinarians, animal keepers, researchers and visitors to obtain objective results. The implementation of sumatran tiger welfare management in Medan Zoo has an average of 76.9 with the category is good and for Siantar Zoo has an average of 95 with the category is very good. Recommendation that needs to be considered from the results of this study is that Medan Zoo needs to add enrichment in the cages that tigers can behave naturally.

Nature tourism is an effort to utilize natural resources that have been designated as tourist attraction objects to be targeted for tourism potential. One of the national strategic natural tourism areas around Lake Toba is Simarjarunjung. This area has an ecosystem of forest areas with very beautiful views that are managed by the community. This study aims to examine how the institutional management of natural tourism objects and the use of natural resources in the Simarjarunjung area of North Sumatra. This study uses a descriptive method with a qualitative approach. The results of this study present various characteristics of the institutional aspects of nature tourism management. Various advantages and disadvantages exist in the form of management institutions, such as the Association of Forest Farmers Groups (Gapoktan), Tourism Aware Groups (Pokdarwis), and individuals/volunteers. The potential of natural resources that are utilized and managed in the form of views of Lake Toba, the natural charm of the mountains, the charm of pine stands, agroforestry ecosystems, and a cool microclimate. The results of the comparison of various institutional models and the use of natural resources can be used as a reference in the development of natural tourism by managers and related stakeholders.

One of the main focuses in microbial ecology is the analysis of microbial communities in water, especially concerning bacteria. The results of the analysis related to the abundance of bacteria will be essential knowledge for the development of aquaculture, especially those relating to the dynamics of pond water quality. This study aims to analyze the total abundance of bacteria and water quality dynamics in the water of Litopenaeus vannamei aquaculture that applies a recirculation system. The study was conducted for three months on a concrete pond plot with an area of 2500 m2. Samples of bacterial abundance were taken from pond water, while water quality checks were carried out at ponds and pond outlets. Sampling was carried out at weeks 1, 3, 5, and 8 during the cultivation phase. Bacterial abundance was calculated using Environmental DNA (eDNA), which refers to DNA extracted from the environment without isolating the target organism. The water quality parameters observed were pH, conductivity, DO, turbidity, temperature, and salinity. This study suggested that the abundance of bacteria from the first to the 8th week were 15.3x107; 17.1x107; 36.6x107; and 35.4x107, respectively. Moreover, DO ranged from 3.2 ppm to 7.6 ppm; temperature ranged from 30 °C to 33.3°C; turbidity raged from 12 NTU to 57 NTU; salinity ranged from 19 ppt to 24 ppt; conductivity ranged from 2.93 s/m to 3.54 s/m, and pH ranged from 6.6 to 7.0. This study indicates that the recirculation aquaculture system in Lamongan, East Java may obtain the optimum water quality and controlling the abundance of bacteria to support the aquaculture of Litopenaeus vannamei.

Urban forests are part of urban green open spaces that are planted to provide direct or indirect advantages such as security, comfort, welfare, and the beauty of urban areas. The study’s objectives were to (1) assess the variety of flora species in the Stabat City Forest and (2) determine the structure of the composition of the species that compose the urban forest. The vegetation analysis approach was used in this study to determine the composition of the forest stand structure in Stabat City. From the results of research in from the results of the study that there are 14 species of trees in the city forest of Stabat which are included in 10 families, namely Meliaceae (14.28%), Moraceae (14.28%), Fabaceae (14.28%) and Myrtaceae (14.28%). The highest IVI value at the seedling, sapling, pole and tree were Oroxylum indicum (44.07%), Swietenia mahagoni (108.90%), Swietenia mahagoni (148%) and Switenia mahagony (76.71%) respectively. Swietenia mahagoni found as the species with the highest IVI value at sapling, pole and tree stage. Meaning that this species dominates the growth level.

Ecotourism is a type of ethical travel that preserves the natural environment while also benefiting the local community culturally, socially, and economically if implemented correctly. Ecotourism in the Bagan Serdang mangrove forest was initiated in 2018 as an effort to make this area as one of the leading tourism alternatives with mangrove-based edu-tourism Recently, the condition of mangrove vegetation is degraded in several spots, facilities and infrastructure are neglected and even damaged, and accessibility is not optimal. These, on the other hand, are some of the factors that must be considered for the feasibility of developing ecotourism in mangrove areas. This research aims to identify the development potential level of Bagan Serdang mangrove ecotourism. Data collecting was done through the field observation and the potency of ecotourism development was measured based on ADO-ODTWA guidebook from Indonesian Forestry Department. The attraction of Bagan Serdang mangrove ecotourism had a moderate potential level with 21 species of vegetation and 9 species of fauna. Accessibility and accommodation had a low potential level, whereas facilities and infrastructures had a high potential level. The low potential criteria were suggested to be priority in the ecotourism development of Bagan Serdang.

The mangrove ecosystem in Forest Managemen Unit - VII (FMU) Sumatera Utara is a natural forest. FMU has not managed and utilizes mangrove forests optimally. It can open up opportunities for illegal loggers and trigger damage to these natural ecosystems. This condition requires prevention and mitigation so that severe damage to mangrove forests does not occur. This study aims to determine the relationship between vegetation index and mangrove density in the field and map the mangrove density distribution based on the image vegetation index value. The density distribution mapping was carried out by compiling a vegetation density estimator model NDVI, GNDVI, and TVI as independent variables. Correlation test and regression analysis between the vegetation index value (NDVI, GNDVI, and TVI) to the number of trees per unit area. The distribution model for the density of mangrove stands was chosen based on the coefficient of determination (R2). The study resulted from NDVI selected as the vegetation index used to map the distribution of mangrove density with a Pearson correlation coefficient (R) of 0.738. The selected model is Y = 2.48e2.8667x, which is an exponential equation with a coefficient of determination (R2) of 61.3%. Based on this model, the distribution of mangrove density has the lowest density reaching 400, and the highest density is 2,200 trees per hectare

Dimensional stability is a significant problem in particleboard. This study aims to analyze the effect of immersing particles in an acid solution on particleboard’s physical and mechanical properties made of kemenyan (Styrax sumatrana) wood and belangke (Gigantochloa pruriens) bamboo. The particles were immersed in each acid solution for 24 h, and then dried to reach 9% water content. The particleboard was made with a 25x25 cm2 with a target thickness and density of 1 cm and 0.70 g/cm3, respectively. After being made into sheets, the next step is hot pressing using a hot press machine that has set the temperature, time, and pressure at 160 °C, 5 min, and 30 kg/cm2, respectively. The results showed that immersion in the acid solution can stabilize the dimensions of the resulting particleboard but does not reduce the strength of the board. Several board properties have met the standards, such as density, thickness swelling, modulus of rupture, and internal bond.

Tree species have received more attention recently due to its contribution and prospective utilization. Although provided many function for human and ecosystem, the existence of trees also threatened due to illegal harvesting and forest conversion. Sustainable utlization approaches were needed for increasing the value and willingness of the community to engage in conservation activities. Although many tropical tree species, especially in North Sumatra, have been exploited, there are still few reports of sustainable approaches to those species. In this study, the assessment of several local tree species in North Sumatra was approached with five conditions adopted from previous research, those were :1) sustainable harvesting, (2) no threat interaction, (3) effective commercialization, (4) economic benefits to farmers, and 5) utilization of financial proceeds to promote conservation initiatives. The results of the study illustrate that although these four criteria are fulfilled, the forest product trade often does not provide sufficient financial benefits to protect forests from other threats. Therefore, it is necessary to understand the interaction between threats for sustainable use and conservation, by using a precise conceptual model. The financial benefits of sustainable use must be adequate to support conservation efforts that can overcome various threats to tree species conservation.

The use of non-wood lignocellulosic materials is currently limited as organic fertilizer, fuel, and animal feed. These materials have the opportunity to be used in the manufacture of particleboard. This study aimed to analyze the properties of the panel made of non-wood lignocellulosic material bonded using melamine-formaldehyde adhesive. Non-wood lignocellulosic materials used in this study include bagasse, corn cobs, durian skin, coconut fiber, and rice husks. The material was converted into 20 mesh size particles. The level of melamine-formaldehyde adhesive used was 10%. Hot pressing was done for 10 min at 140oC using 30 kg/cm2 pressure. The board is made of 25 x 25 cm2 with a target density and thickness of 0.80 g/cm3 and 1 cm, respectively. The findings revealed that bagasse board has superior physical and mechanical properties to other lignocellulosic materials. This board has the highest internal bond and the lowest thickness swelling value. Most of the test parameters in this study did not meet the JIS A 5908-2003 because the density target was not achieved.

West Binjai is a sub-district located in Binjai City, North Sumatra. Green Open Space is also part of the Binjai city’s planning scheme which has many benefits for the community and the environment. This research used Normalized Difference Vegetation Index (NDVI) analysis and NDVI value classification results in the distribution of vegetation density. Analysis of changes in vegetation density was carried out between 2015 and 2020 in West Binjai. The largest change in the area of vegetation density classes in the West Binjai between 2015 and 2020 was the increase in the area of the high dense class to 19.13%. The sub-district has green open spaces in the form of sub-district parks, public cemeteries, road green lane, river bank and private green open spaces. These green open spaces were in the low dense, medium, dense and high dense classes. There is a need for rearrangement of green open spaces, especially those within low dense class. Replanting trees are also essential to increase the quality of the green area. Improving the quality of green space will lead to the enhancement of quality of environment.

The existence of megabenthos has an important role in maintaining sustainability of coral reef ecosystems and in the food web process. Megabenthos is also often used as an indicator of the health condition of coral reefs. The purpose of study was to analyze the biodiversity of megabenthos associated with coral reef in Tuan Island. This research was conducted in July -September, 2020. There were four research stations determined by purposes method based on four wind directions. Megabenthos data collection carried out by benthos belt transect method and coral reef data collected by using the Line Intercept Transect (LIT) method. The results were found 8 species of megabenthos target, namely spiny starfish (Acanthaster planci), blue starfish (Linckia laevigata), sea urchins (Diadema setosum), sea cucumbers (Holothuria atra), clams (Tridacna squamosa), Drupella snails (Drupella sp.), lola clams (Tronchus niloticus) and lobster (Panulirus versicolor). Totally, there were 190 individuals of megabenthos with the abundance ranged from 0.18 to 0.52 individuals/m2. Diadema setosum had the highest abundance with the value 0.9 individuals/m2 followed by Drupulella sp. (0.3 individuals/m2). The highest diversity index was station 4 followed by station 3, 2, and 1 with the value of 2.21, 0.85, 0.64, and 0.41, respectively. The diversity index was categorized as low and medium. The average of evenness and dominance indices were 0.04 and 0.62, both was medium category. The highest percentage of coral cover was at station 1 followed by station 3, 4, and 2, the coral cover value were 50.44%, 29.20%, 18.14%, and 9.29%, respectively. The correlation (r) between the percentage of coral reef cover and megabenthos abundance has a positive correlation, but the level of correlation was low (0.215 %). The density of megabenthos on Tuan Island did not have a major influence on coral reef cover where the determination value (R2) was 0.0462 which indicated that the megabenthos abundance was influenced by the percentage of coral reef cover only 4.62%.

Deli Serdang is one of the regencies in North Sumatra Province, experiencing relatively rapid development and population. Increasing in demand for the availability of land as living space. Two sub-districts of upstream watershed experienced changes in land cover, namely; Sinembah Tanjung Muda (STM) Hilir and STM Hulu. Monitoring changes in land cover in both sub-districts is essential, given that they are located in the upstream area of the watershed and will impact other areas in the lower watershed. This study aims to analyse land cover changes in both sub-districts over ten years (2009 - 2019). The method used in calculating land changes that occur is change detection. Field surveys were carried out to ensure that the land cover conditions on the land cover maps followed the field’s actual conditions. The research shows the period of 2009 – 2019, land cover that has increased in the area are mining, industry, open land, settlements, livestock and shrubs. The decrease in the area occurred in land cover, including dryland forest, mixed gardens and cultivated land.

Village life around the forest is inseparable from the existence of the forest. The use of raru as a forest product has been passed down from generation to generation in the community of Bonalumban Village, Tukka District, Central Tapanuli Regency, North Sumatra. The study of community perceptions and dependencies on Raru in Bonalumban village is needed to determine the potential of raru and encourage efforts to preserve raru. The method of selecting respondents is done by purposive sampling by selecting general respondents and specialized respondents. Data analysis uses descriptive statistics. Public perceptions about the existence of raru in nature are still plentiful so there is no public effort to regenerate. Community dependency on raru is grouped into four categories, that is for sale, palm wine concoctions, animal cages, and building materials. Raru harvesting activities by felling without being accompanied by cultivation activities causes the presence of raru vegetation to decrease.

Jambi Province has a very extensive forest area. However, the forest area in Jambi Province continues to decline due to forest and land fires which result in changes in land cover every year. There have been large-scale forest and land fires in Jambi Province in 2019. The objectives of this study to determine the temporal and spatial distribution of hotspots in Jambi Province and to find out changes in the land cover before and after forest and land fires in 2019. The method used in this study was an analysis of the temporal and spatial distribution of hotspots and satellite imagery processing of land cover at locations with the highest hotspot density. The period of increasing hotspots in Jambi Province in 2019 occurred from August to December and reached a peak in September. The highest hotspot density was in Muaro Jambi District. Land cover that experienced forest and land fires was dominated by palm oil plantation and swamp shrubs. The forest and land fire incidents generally occur at the same location over the years.

Sodium acetate anhydrous (SAA) added into sweet potato starch to prepare acetylated starch at dissimilar levels (2-12 g), were evaluated. Three main parameters that were compared were swelling power (SP), solubility (S), and water binding capacity (WBC) of starches. The SP and S of sweet potato starch ranged from 16.26-30.41g/g and 1.58-5.24%, respectively. Moreover, the WBC obtained are 76.07-107.50%. The acetylated starches showed higher SP, S, and WBC than native starches, and it’s increase with the addition of SAA in the medium. The objective was to determine the effect of SAA addition into the medium until the higher response obtained. Overall, the best treatment found at the addition of 10 g SAA. Native and treated starches were analyzed using SEM, FTIR, and rheometer to know the flow behavior of starches. The diversity obtained in the starches’ properties was important for some industrial requisites.

Potato starch becomes one of the popular starches. It is preferred for use in various industries due to its unique characteristics such as a good film-forming ability and consistency. The high phosphate content causes potato starch to have the excellent ability of water binding, swelling, and good consistency. However, potato production in the developing country tends to decrease. Local tubers could be used to be an alternative to substitute it. The modification process could improve the physicochemical and functional properties of the native local tubers starch. Sweet potato has the potential to be developed to substitute potato starch because it comes from the Solanaceae family. Hydroxypropylation, succinylation, and phosphorylation are suggested in producing potato starch substitute.

This study aims to develop and analyze the feasibility of collaboration skills based on the Collaborative Problem Solving (CPS) rubric in junior high school science learning which is feasible from the aspects of validity and practicality. The research method used is the method of research and development of the Borg and Gall model which is limited to only 7 stages. Data collection techniques and tools are adapted to the research stage. The results of the validation of the research content using the Lawshe formula obtained CVI (Content Validity Instrument) = 0.99. Practicality tests through a questionnaire response to educators in a limited manner obtained positive statements of 92.55% and widely obtained positive statements of 97.35%. The conclusion of this research is that collaborative skills rubric is feasible to be used to measure collaboration skills in science learning in junior high schools.

The use of technology has entered all aspects of human activities, belonging education. The use of computer-based media in the learning process is very useful. This study aims to describe the results of various studies on the use of computers in the learning of mathematics. The method used is descriptive research. The aspects seen are the various types of software used and their effects on mathematics learning. Based on the results of the research, it can be concluded that the use of computers can help students visualize and understand mathematics material.

The COVID-19 pandemic that attacks the respiratory tract is spreading rapidly to all regions in Indonesia. In this pandemic situation, daily products such as sprays, tissue paper and masks need to be developed using nanomaterials. In this paper, graphite carbon and zinc oxide were synthesized using gelatin as a pore guide. The morphology and character of graphite carbon and zinc oxide were characterized by SEM, EDX and XRD to address appropriate active centers to counteract the protein spike interaction in covid-19 with ACE in the human body. Several illustrations are presented in this paper to understand the opportunity of carbon and zinc oxide materials as the basis for making antiviral devices to store viral molecules so that human-to-human transmission can be prevented.

Sweet potato is a common tuber in Indonesia, however it is less popular than cassava and corn. Sweet potato is alsorich for starch that can be used for many industrial applications, although it still have many drawbacks in native form. Pregelatinization can be used to overcome those drawbacks and increase its value. The swelling power (SP), solubility (S), and water binding capacity (WBC) of pregelatinized white sweet potato starch were analyzed. The starch were pregelatinized with different temperature at 35, 40, 45, 50, 55, 60°C. The swelling power and solubility of sweet potato starch ranged from 16.26-30.30 g/g and 1.58-26.39 %, respectively. Moreover, the WBC obtained are 76.07-232.37 %. Pregelatinized sweet potato starch showed a higher SP, S, and WBC as the increasing of temperature until some point. The variation obtained in the starches’ properties was important for some industrial requirements.

This study aims to analyze the conception, threshold concept, and troublesome knowledge in chemical reaction topic. This study uses qualitative methods, document analyses, as well as interviews with chemistry teachers to obtain information about threshold concepts and troublesome knowledge. From the results of the analysis of several journals obtained that there were still many misconceptions encountered when students study chemical reactions. While the results of the interview, threshol concept in chemical reaction consisted of mixtures, physical and chemical properties, material changes, concepts of protons and electrons, electron configurations, chemical bonds, intermolecular forces, attractive forces between charges, compound nomenclatures, chemical formulas, and Lavoisier’s laws. While troublesome knowledge includes complexity of particles involved, complexity of interactions that may occur, complexity of applying Lavoisier’s Law, and language used.

Rainfall is an important factor in many fields, such as aviation and agriculture. Although it has been assisted by technology but the accuracy can not reach 100% and there is still the possibility of error. Though current rainfall prediction information is needed in various fields, such as agriculture and aviation fields. In the field of agriculture, to obtain abundant and quality yields, farmers are very dependent on weather conditions, especially rainfall. Rainfall is one of the factors that affect the safety of aircraft. To overcome the problems above, then it's required a system that can accurately predict rainfall. In predicting rainfall, artificial neural network modeling is applied in this research. The method used in modeling this artificial neural network is backpropagation method. Backpropagation methods can result in better performance in repetitive exercises. This means that the weight of the ANN interconnection can approach the weight it should be. Another advantage of this method is the ability in the learning process adaptively and multilayer owned on this method there is a process of weight changes so as to minimize error (fault tolerance). Therefore, this method can guarantee good system resilience and consistently work well. The network is designed using 4 input variables, namely air temperature, air humidity, wind speed, and sunshine duration and 3 output variables ie low rainfall, medium rainfall, and high rainfall. Based on the research that has been done, the network can be used properly, as evidenced by the results of the prediction of the system precipitation is the same as the results of manual calculations.