bluuebunny/crossref_metadata_2025 huggingface dataset:
Sequences analysis and phylogenetic of leukemia DNA
Authors: Lusiyanti D , Nacong N , Irawan M I
Published: February 2021

DNA is one part of a biological sequence other than RNA and protein. DNA is a nucleic acid that stores all the unique biological information of every living thing and several viruses. Someone who has an illness can be seen in the structure of the DNA which can then be compared with other DNA structures. This process is part of sequence analysis which is the core of bioinformatics. This study aims to analyze the results of sequences alignment of cancer. The sequence was obtained from DNA leukemia taken from GenBank (www.ncbi.nlm.nih.gov). In the sequence analysis, the most basic thing is the sequence alignment. Alignment results can provide information about the level of similarity in the structure of the two sequences. This study will apply the Super Pairwise Alignment method that is implemented in JAVA-based programming languages. Alignment results are carried out by giving different values of gap penalty and gap extend. The results of the study obtained different alignment values, this proves that there is a significant effect of the selection of core parameters used in alignment.
Effect of thermoelectric placement on the commercial waterblock to the liquid cooling system performance
Authors: Kennedy  , Anwar K , Muis A , Basri B , Ilhamsyah M
Published: February 2021

Thermoelectric liquid cooling systems have been widely used to maintain the temperature of electronic devices due to their small size, compactness, and simplicity. A few of these cooling systems utilize the waterblock as a liquid heat exchanger. This study aims to determine the performance of a thermoelectric-based water cooling system in a commercial waterblock. The research was conducted in the laboratory using a 4x12 cm aluminium waterblock placed on the cold side of TEC1-12715. Three variations of thermoelectric placement have been carried out; at the inlet and outlet, in the middle, and the end of the waterblock. The temperature of the coolant and the flow rate of the cooled fluid are kept constant for these variations. The results showed that the thermoelectric position on the waterblock affected the rate of reduction in fluid temperature and the cooling system’s performance.
The sensitivity of Covid-19 spread model parameter: an effort to point out the importance of the detection program
Authors: Ratianingsih R , Hajar H , Rahmah A A , Jaya A I
Published: February 2021

The pandemic of covid-19 has been spread in entire the world. Unfortunately, some regions in Indonesia are ignoring the detection program as an important prevention in control the disease. This research notice some parameters that play a role in the behaviour of covid-19 spread model. The parameters describe the level and rate of the transition and interaction behaviour of the variables, the number of susceptive, unsympthom, quarantined, infected and recovered population with respect to time. The reproduction number, governed from the matrix generation of the mathematical model, shows that the parameters determine the disease spread status. The mathematical model is governed from the disease spread diagram that derives a nonlinear partial differential equation system. The reproduction number is nothing but the thresh hold of the spread disease. To keep the disease spread to be controllable, the reproduction number of the model have to be arranged less than the thresh hold. The appearance of the parameters interpret that the detection program in important to be pointed out.
Study of reducing Chromium (VI) to Chromium (III) ion using reduction and coagulation methods for electroplating industrial waste
Authors: Azis M Y , Amedyan N N , Hanefiatni  , Suprabawati A
Published: February 2021

The electroplating industrial waste is the primary source of environmental pollution due to heavy metal chromium (VI). The method commonly used in treating chromium (VI) metal waste in industry is by reduction and coagulation. Chromium (VI) metal is very toxic because it is very unstable compared to chromium (III). Therefore, chromium (VI) waste must be reduced to chromium (III) before it will be discharged into the environment. The purpose of this study is to find the optimum conditions in reducing levels of chromium (VI). The method used is reduction with sodium metabisulfite, coagulation with Polyaluminium chloride (PAC), and a combination of both. The percentage of reduction obtained in the reduction, coagulation, and combined methods is 96.36%; 20.57%; and 98.57%, with the optimum dose of reducing agents and coagulants of 330 mg/L and 300 mg/L. The best method to reduce the level of chromium (VI) is the combined method at a percentage reduction of 98.57% with a standard deviation of 0.0046 and %RSD of 0.43%. The electroplating waste has reduced percentage until 98,39% at using combination methods.
Leaching of limonitic nickel from Sorowako with sulfuric acid at atmospheric pressure
Authors: Safitri N , Mubarok M Z , Meidji I U , Hardi J , Jayadi H
Published: February 2021

Indonesia has the largest nickel laterite reserves in the world that it plays an important role in fulfilling the demand for stainless steel, nickel-based alloys, and the issue of using electric cars in the future. Currently, low-grade nickel laterite ore has not been maximally processed into value-added products domestically. The extraction process that is widely applied in the industry for low-grade laterite nickel ore through the hydrometallurgical route, which is the leaching method at atmospheric pressure in a sulphuric acid solution. The characterization of nickel ore from Sorowako has been studied that included water content analysis, sieve analysis, XRF analysis, XRD analysis, and leaching in sulphuric acid solution with agitation method at various leaching times. The results showed that the nickel ore sample from Sorowako had a water content of 5.51% with a dominant size fraction of -4 +14 mesh. XRD and XRF analysis results have shown that the chemical compositions of laterite nickel from Sorowako were Limonitic type of goethite (FeOOH) and quartz (SiO2) with the content of Ni, Co, Mg, and Fe of 1.5%, 0.02%, 0.05%, and 23.82%, respectively. The highest percentages of nickel and iron extract that were obtained at the 12 hour leaching time were 90.01% and 97.11%, respectively.
Near-surface evaluation of Bora office area using MASW methods on land-streamer
Authors: Muin M R , Kurniawan M , Musa M D T , Winata E , Batalipu A I , Sahabuddin  , Alfayed F , Marwah S , Anjarsari R , Maulana M I A
Published: February 2021

A limited seismic investigation of the Bora Office Area, was conducted using multiple seismic methods including multi-channel analysis of surface waves (MASW), using land streamer originally designed by the author. The main feature of the land streamer tool is the non-stretch woven belt on which geophone units are mounted to form a multichannel geophone array similar. As a result, it was concluded that it might be possible to avoid higher-mode contaminantion at low frequencies at sites with hight (Vs), it can be seen that the distribution of Vs values varies over the range of 240 m/s to 420 m/s. In general, can be divided into 2 layers based on the value of Vs 100 - 250 m/s as soft rock and > 250 m/s as hard rock. There is a soft rock at a depth range of 0 to 5 m with a velocity value of 140-260 m/s, and hard rock layers at a depth range of below 5m with a velocity value of 280 - 400 m s.
Modelling the number of HIV/AIDS in Central Sulawesi
Authors: Utami I U , Setiawan I , Daniaty D
Published: February 2021

The spread of HIV/AIDS in Central Sulawesi is centralized and spreads in certain districts or cities so that there are indications of a spatial effect in the spread of HIV/AIDS. Geographically Weighted Negative Binomial Regression (GWNBR) is one of the right solutions for modelling the relationship between response variables and explanatory variables on counted data that is local for each observation location with overdispersion and the influence of location or spatial aspects on the data. Spatial aspects can be caused by geographic, socio-cultural, economic conditions, as well as different people’s knowledge between regions. Overdispersion is a condition where the variance of the data is greater than the average data. This study aims to determine the GWNBR model and the factors that influence the number of HIV/AIDS cases in the province of Central Sulawesi. The obtained result based on GWNBR model shown that the districts with the most number of districts that have the most significant similarities in variables are divided into nine subdistrict groups. Factor affecting the number of HIV/AIDS cases in Central Sulawesi Province in 2018 was population density.
Sediment thickness mapping and soil classification using ellipticity inversion of Rayleigh wave in the eastern part of Mataram City, Indonesia
Authors: Meidji I U , Rusydi M , Asrafil  , Jayadi H , Safitri N
Published: February 2021

A soil’s dynamic characteristics greatly influence earthquake potential damage inland. Subsurface investigations to determine the dynamic characteristics of the soil can minimize the risk of such damage. The sediment layer thickness is one of the parameters to assess the local geological character in response to an earthquake. Another parameter is Vs30 value, which is used to classify soil types as an indicator of soil response, which generally dominates ground motion amplification. In this study, the two parameters are analyzed to determine the potential for local damage in the event of an earthquake in the eastern area of Mataram City using the rayleigh wave inversion from microtremor data. The research area covers 3 districts, including Selaparang, Cakranegara, and Sandubaya Districts. The results showed that the value of the sediment thickness in the entire study area ranged from 12.78 m to 57.20 m. The value of Vs30 varies between 286 m/s to 866 m/s with the classification of rigid soils, very dense soils, and soft rocks and rocks. These results indicate that the study area in general experiences a large potential for damage if an earthquake occurs. This research is expected to be a reference for the spatial plan of Mataram City.
Analysis of calcium levels in beef bones from kaledo waste
Authors: Supriadi S , Rahmawati S , Aminah S , Ningsih P , Hastuti S , Said I , Setyawati A
Published: February 2021

Kaledo is one of the special culinary from Central Sulawesi which containing beef bones. The large number of restaurants that provide kaledo in their menus resulted in the amount of beef bone waste that cannot be consumed. This waste can cause environmental problems. However, the bones have the number of minerals, one of them is calcium (Ca). Ca is a mineral that is needed by the body in maintaining body functions. This study aimed to determine the calcium levels in beef bones from kaledo waste which was taken randomly from the kaledo restaurant in Palu. Determination of calcium levels in beef bones from kaledo waste used atomic absorption spectrophotometer. The results of the analysis showed that the water content was 4.5950%, and the ash content was 61.7424%. The analysis of calcium levels measured at a wavelength of 422.7 nm was 19,6800 mg/L. The results of this study are expected to be a source of information about the levels of calcium contained in cow bones from kaledo waste, and it can be used further as a substance in the utilization of beef bones from kaledo waste as a food that can meet the body’s need for calcium intake in preventing stunting.
Application of geoelectrical methods for estimating the availability of shallow aquifer layers
Authors: Sastrawan F D , Romadhon W
Published: February 2021

Kalimantan Institute of Technology (ITK) is the only institute of technology in Kalimantan with an area of ±300 Ha. Most of the area of ITK is not built yet. The increasing of interests of people to study in ITK causing the institute to build more lecture facilities to fulfil the people’s interests. Along with its development, it needs an independent clean water resource. The main source of clean water is groundwater. The potential of groundwater in its unbuilt area can be known by using geoelectrical method measurement. Geoelectrical method could give an early representation of the earth’s subsurface condition based on the resistivity parameter. This research produced a 1D cross section of the earth’s subsurface resistivity. Based on the result, it is known that the land cover is a red-yellow podzolic and clayey sand with the resistivity value of 300 – 570 Ωm and 2 – 4 meters of thickness. The second layer is a layer of water-saturated clay associated with low resistivity values of 15 – 44 Ωm with 20 meters of thickness. The third layer is a clayey sand layer which is estimated as aquifer layer in the depth of 9 – 24 meters. There is also an anomaly of coal inserts at VES_1 measurement point in the depth of 17 meters with a resistivity value of 962 Ωm.
Electrochemical performance of carbon paste electrode modified TiO2/Ag-Li (CPE-TiO2/Ag-Li) in determining fipronil compound
Authors: Nurdin M , Arham Z , Rasyid J , Maulidiyah M , Mustapa F , Sosidi H , Ruslan R , Salim L O A
Published: February 2021

Electrochemical studies in detecting persistent organic pollutants (POPs) have attracted a lot of interest from researchers, especially the carbon paste electrode (CPE). The research objectives were to determine the electrochemical characteristics of TiO2/Ag-Li on the CPE in the system Fe2+/Fe3+ and determine the fipronil in solution. TiO2/Ag-Li preparation was carried out by using the sol-gel method. Electrochemical performance of CPE was applied by cyclic voltammetry. The system developed was a reversible redox reaction and have peaks Ipa 110 µA and Ipc 105 µA. We also found that the composition of the best modifier addition to CPE was using TiO2/Ag-Li with a mass of 0.005 g. The optimum scan rate for the measurement of the fipronil test solution was obtained at 0.2 V/s with an Ipa value of 15 µA and an Epa value of 0.40 V. Based on the plot between the root scan rate and the oxidation current of the solution containing fipronil, the obtained R2 value was 0.9806. This research provides the development of modifier CPE material with the well electrochemically performance and considered as a very effective monitored system for the environment contaminated by POPs waste.
Antimicrobial activity of secondary metabolite compounds from lichen Teloschistes flavicans
Authors: Maulidiyah M , Suilowati P E , Musdalifah A , Kusmalwaty T , Imran I , Azis T , Watoni A H , Hasan A , Salim L O A , Nurdin M
Published: February 2021

Exploration of lichen natural compounds has attracted a lot of attention from researchers as potential medicinal raw materials because chemical compounds contained in lichen have many properties. The potential for developing secondary metabolite compounds of lichen has become a trend for various benefits, for example, in cosmetics, agriculture, health, and food. Lichen Teloschistes flavicans was a concern to study because there were not many reports of secondary metabolites that have antimicrobial activity. The research objective was to examine antimicrobial activity using 3-[1’-(2”,3”-dihydroxy-phenyl)-propyl]-7hydroxy-chroman-4-one compound from lichen Teloschistes flavicans. The antimicrobial activity test was a well diffusion method. Bioactivity was determined by calculating the clear zone formed around the well. Antimicrobial activity testing indicated the inhibition of bacterial growth at a concentration of 500 ppm and 1000 ppm with the respective inhibition zones namely E. coli (10-11 mm), S. Typhi (2-5 mm), K. pneumoniae (11-13 mm), and S. aureus (10-13 mm). Also, B. cereus bacteria and C. albicans fungi were only inhibited at a concentration of 1000 ppm with an inhibition zone of 6 mm each. This research provides scientific knowledge about the potential development of lichen T. Flavicans as an antimicrobial.
The effect of calcogenate sulfur on the performance of the S-TiO2/Ti electrode as a photoelectrocatalytic sensor for phenolic compounds
Authors: Muzakkar M Z , Azis T , Rajiani M S P , Maulidiyah M , Irwan I , Mustapa F , Salim L O A , Nurdin M
Published: February 2021

The TiO2/Ti and S-TiO2/Ti electrodes are effectively prepared using the anodizing process. The objective of this analysis is to determine the characteristics of the S-TiO2/Ti electrode and its efficiency as a photoelectrocatalytic sensor device. The composite electrode of S-TiO2/Ti was prepared using the Ti plate anodizing method in glycerol and NH4F 0.27 M with a bias potential of 25 V for 4 h followed by calcination at 500 °C for 90 minutes. Doping S to the TiO2/Ti electrode was carried out in sol-gel containing sulfur by the dip-coating process and then calcined for 10 minutes at 150 °C. The obtained TiO2/Ti and S-TiO2/Ti electrodes are characterized by UV-Vis DRS, XRD, SEM-EDX, and FTIR techniques. TiO2/Ti was shown to be active under UV light, while S-TiO2/Ti was active under visible light. We also observed that the best composition of the S-TiO2/Ti electrode was 1 M with a current value of 5.71x10−5 A in the visible area. The S-doped TiO2/Ti electrode photoelectrocatalytic activity was stronger than the undoped electrodes under visible light area irradiation.
Trends in composition and density of marine litters on the Mamboro Beach
Authors: Putra A E , Sulistiawati D , Safir M , Mansyur K , Rizal A , Serdiati N
Published: February 2021

The coastal zone is an intermediate area between land and sea which is very vulnerable to being contaminated by litters. The density and composition of marine litters is strongly influenced by environmental factors and human activities. The research objective was to monitor trends in composition and density of litters on the Mamboro Beach in 2019 and 2020. The sampling method is based on marine litter guideline monitoring formulated by the Ministry of Environment and Forestry which was adopted from UNEP and NOAA. The results showed that the total litter weight for macro size (> 2.5 cm) has decreased by 4303.29 g (56.23%) from 2019 to 2020. Likewise, meso size (0.5-2.5 cm) has decreased by 902.25 g (18.42%) from 2019 to 2020. Meanwhile, both litter sizes have increased in density for macro size by 14.12 pieces/m2 and meso size by 18.92 pieces/m2 from 2019 to 2020. The decline in the trend of macro and meso litter in 2019-2020 period is not always directly proportional to the litter density on the Mamboro beach. Apart from anthropogenic and infrastructure factors, geomorphological characteristics, weather conditions and oceanographic parameters also have an influence on the composition and density trends of litter in coastal areas.
Printing of PEDOT:PSS for top gate organic thin film transistor
Authors: Darwis D , Sesa E , Elkington D , Sharafutdinova G , Lewis T , Zhou X , Dastoor P C. , Belcher W J.
Published: February 2021

This report present a thorough discussion of the DOD inkjet printing technology, including technical skills and information about Dimatix inkjet printer employed for the realisation of devices. The use of inkjet printing for the deposition of the conducting polymer PEDOT:PSS was successfully demonstrated for top gate electrode organic thin film transistors. This investigation offers a significant contribution in order to the efficient fabrication of OTFTs.
The length of reaction time on the synthesis of poly (3,4-ethylenedioxythiophene)
Authors: Diah A W M , Wirayudha A , Supriadi  , Santoso T
Published: February 2021

Poly(3,4-ethylene dioxythiophene) (PEDOT) has been synthesised via the oxidative polymerisation method of 3,4-ethylenedioxythiophene (EDOT) monomer using Na2S2O8 and Fe2(SO4)3 as oxidising agents. The synthesis was carried out at various times of reaction, i.e for 6, 12, and 24 hours. The success of PEDOT synthesis was proven by FTIR spectra which indicated by the loss of the C-H group presented in the 890 cm−1 absorption area from EDOT monomer. The morphology of PEDOT particles was observed by Scanning Electron Microscopy (SEM). The results showed that the differences in the synthesis time of 6, 12, and 24 hours affected the diameter of PEDOT particles. The size morphology of those 6, 12, and 24 hours synthetically PEDOT particles were 38.64 ± 18.21 nm, 55.91 ± 15.31 nm, and 66.62 ± 18.92, respectively. The largest diameter product of PEDOT in this study was then doped with carrageenan to synthesis PEDOT/Carr dispersions via the post-polymerisation method. This study concluded that the size of PEDOT particles is significant with increasing time of reaction, and the product of PEDOT/Carr dispersions is promising as a green polymer.
Geospatial approach to determining potential of springs at the Palu Groundwater Basin for post disaster water supply in Central Sulawesi Province
Authors: Zeffitni
Published: February 2021

The disaster that occurred on 28 September 2018 in Palu City, Sigi and Donggala regencies had an impact on damage to a number of water resource. This study aims to determine the quantitative potential of springs with using a geospatial approach and hydrogeomorphological mapping. Based on the results of the field survey, the springs in Palu Groundwater Basin amounted to + 104 springs with divisions in the east and west. The results showed that in Palu Groundwater Basin the appearance of springs was not only caused by geomorphological conditions but also influenced by geological conditions. Based on the type of springs, it is dominated by the type of artesian, fracture and contact. The quantitative potency level of springs ranges from small (< 5.0 liters/second) to large (> 10.0 liters/second) quantitative potency levels. Small quantitative potential levels (< 5.0 liters/second) in the eastern part include the districts: East Palu, South Palu, Dolo and Biromaru. The western part of Palu Groundawter Basin includes the sub-districts: West Palu and South Palu. Based on the results of the study, it can be concluded that the quantitative potential of springs is very potential to meet the needs of clean water in post-disaster areas.
Determination risk of liquifaction disaster based on spatial distribution unconfined aquifer at the Tindaki Groundwater Basin, Parigi Moutong District
Authors: Ninasafitri  , Zeffitni
Published: February 2021

Natural disasters such as earthquake, tsunami and liquefaction in Central Sulawesi Province in 2018 had a significant impact on economic growth. This demands disaster risk reduction, especially liquefaction disasters. This research was conducted in Tindaki Groundwater Basin, Parigi Moutong Regency, especially in Parigi sub-district, which includes: Lebo, Bambalemo, Kampal, Maesa, Bantaya, and Olaya. The purpose of this study was to determine the level of risk of liquefaction based on the spatial distribution of the unconfined aquifer in Tindaki Groundwater Basin. The number of samples is 100 points taken randomly, consisting of community dug wells to obtain phreatic depth. The technique of collecting data is random and proportional sampling.The method used in this study is geological and hydrogeological approaches with rock formation as a determining parameter for groundwater density. The results showed that the average depth of the phreatic level was <10 meters from the ground and was in the alluvium formation. Based on the results of the study, it can be concluded that the potential for liquefaction in the research area is in the medium to high potency.
In vitro antioxidant assay and qualitative phytochemical estimation of Meistera chinensis from Southeast Sulawesi
Authors: Musdalipah  , Karmilah  , Tee S A , Yodha A W M , Sahidin I , Fristiohady A
Published: February 2021

Meistera chinensisis one of the species that belong to the Zingiberaceae family. Many antioxidant properties have been reported from this family. Thus, we aim to investigate the antioxidant activity ofMeistera chinensisand its secondary metabolites. The ethanol extract ofM. chinensiswas fractioned and obtained Ethyl acetate Fraction (FEA), Precipitate Fraction (FEN), and fraction 1-8 (F1-F8). The fractions were assayed with DPPH (1,1-diphenyl-2-picrylhidrazyl) and ABTS (2,2’-azino-bis-[3-ethylbenzothiazoline sulphonate) for their scavenging activity in vitro. Ascorbic acid and Trolox were used as control. The phytochemical screening was qualitatively conducted with a colorimetric method. The IC50 value of FEA, FEN, F1-F8, AA, and TX according to DPPH were 35.61±2.22; 47.62±2.93; 90.05±2.27; 105.34±0.83; 97.72±1.16; 112.59±1.22;72.81±2.36; 66.67±2.55; 59.47±2.23; 40.93±2.68; 8.84±0.69; and 11.45±0.87 mg/L, respectively. Similiar with ABTS method that exhibited IC50 were 37.27±3.43; 52.10±3.29; 94.19±4.23; 110.40±3.01; 102.80±2.66; 115.71±3.14; 73.60±3.20; 61.98±3.94; 42.70±3.53; 9.58±0.57; and 12.55±4.02, respectively. The secondary metabolites inMeistera chinensiswere phenolic compounds, flavonoids, steroids, terpenoids, alkaloids, and saponins. In conclusion, we confirmed thatMeistera chinensishas antioxidant capacity for scavenging the free radicals, and the metabolites inM. chinensismight play a vital role in its activity.
Improvement of the Ability of Representation, Reasoning, and Self-Efficacy of Prospective Mathematics Teacher Students by Using Learning with A Scientific Approach
Authors: Darta  , Saputra J , Eliyarti W , Putra B Y G , Kandaga T
Published: February 2021

This research was developed aiming to (1) Analyzing the improvement of representation, reasoning, and SE skills by using a scientific approach to prospective teacher students. (Already done); (2) Analyze the association between the ability of representation and reasoning with SE. (Already done); (3) Analyzing the relationship (association) between the ability of representation and reasoning seen from the level of student ability (low, medium, and high). (Already done); (4) Designing a scientific approach and teaching materials based on the association between ability and level of student ability, in order to improve the ability of students who still have a level of concrete representation to the level of abstract representation, so as to improve reasoning. This type of research is Research and Development. the Four-D model proposed by Thiagarajan (Buhari, 2014) with a mixed method (the multiphase design), through stages: Define, Design, Develop, and Disseminate, namely the definition, design, development, and distribution. The conclusions of the research are (1) the increase in reasoning ability increased significantly at the value of 0.43 with the moderate category. (2) Increasing the ability of representation increased significantly at 0.34 with a moderate category. (3) The increase in SE increased significantly at 0.31 in the medium category. (4) There is a significant positive correlation between reasoning ability and SE, but the correlation coefficient between reasoning ability and SE is 0.338 which is categorized as weak. (5) There is no significant correlation between the ability of representation and SE, with the correlation coefficient between the ability of representation and SE of 0.228 which is categorized as very weak and the direction is positive. (6) There is a significant positive correlation between the ability of reasoning and representation in students with high ability with the correlation coefficient between reasoning and representation ability is 0.889 which is categorized very strong and the direction is positive. (7) There is a significant positive correlation between the ability of reasoning and representation in students with moderate ability with the coefficient of correlation between reasoning and representation ability is 0.838 which is categorized very strong and the direction is positive.
The relation between spatial reasoning and creativity in solving geometric problems
Authors: Novitasari Dwi , Risfianty D K , Triutami T W , Wulandari N P , Tyaningsih R Y
Published: February 2021

Spatial reasoning has been used in daily life, such as in building designs, determining routes and using maps. Spatial reasoning is also used in mathematics, especially in geometry. Therefore, this study aims to find out how spatial reasoning is used by students in solving geometry problems, especially in their creativity to transform 2-dimensional images into 3-dimensional images. Creativity in this study is focused on fluency, flexibility, and originality. This study is an explorative descriptive study through a qualitative approach. The subjects of the study are 11 third grade junior high school students. Data were collected by geometry problem-solving tests with two types of questions in the form of true or false statements and open-ended problems. The results showed that: (1) in terms of fluency, students gave an average of three correct answers out of five, (2) in terms of flexibility, there were five different types of answers, and (3) in terms of originality, there are two students who gave different answers than other students. The results also showed that students applied their spatial reasoning in the form of spatial visualization and mental rotation in their creativity to solve the problems.
Assessing the effectiveness of using digital mathematics technology on student mathematics learning
Authors: Nurfalah Edy , Yuliastuti R , Rahayu P , Sulistyaningrum H , Surawan
Published: February 2021

Digital knowledge is very important in mathematical knowledge to understand steps and logical thinking. Some obstacles were found that mathematics lecturers did not apply their mathematical skills to the maximum when training students in a class. It was also shown from the results of identification: the time given by lecturers in short, the lack of facilities used by students, and the lack of time on campus to use information and communication technology, and the lack of access to digital resources for students to access the mathematical material needed. To deal with these problems, this analysis provides a choice of solutions for better learning. Many choices of digital technology that can be used in student mathematics learning. Such as online learning, based on social media, digital media, interactive questions or discussions, the use of mathematical software, and other digital media that can be used anywhere and anytime.
Students Reasoning Capabilities to Solve HOTS Geometry Materials
Authors: Setyahastuti Esti , Riyadi  , Triyanto
Published: February 2021

This study aims to describe students’ reasoning abilities to solve HOTS questions on geometry material. Type of this research is descriptive qualitative. Subjects of the research were 10 students of 12th grade at Senior High School which were taken using a purposive sampling technique. Data collection was obtained from the result of reasoning ability tests and interviews. The validity of the data in this study used a triangulation method. Based on the analysis of data obtained: 40% of students can submit allegations, students that can do mathematical manipulation and give a reason with proof through the solution both of them are 30%, and only 10% of students can draw conclusions from statements and check the validity of an argument. The results of this study indicate that students’ reasoning abilities are still low. Many students are not able to draw conclusions from statements and check the validity of an argument. This is caused students having difficulty determining the distance in space, besides that it has not been able to connect statements that correspond to the problem of question.
The Use of Magnetic Cube and Sticks Media in STEM-Based Learning (Science, Technology, Engineering, and Mathematics)
Authors: Susanti Eva , Kurniawan Haris
Published: February 2021

This research resulted in a method or learning path that is appropriate for learning mathematics about number patterns using magnetic cube media and STEM learning. The method of this research is design research with three stages, namely: preliminary design, experimental design, retrospective analysis. With the research subjects 32 students of class VIII.7 in SMP Negeri 27 Palembang. Data was collected through observation sheets, video recordings, interviews, photo documentation, and student activity sheets. The data collected was then analyzed retrospectively collected on HLT (Hypothetical Learning Trajectory). From the results of data analysis, it can be concluded that this research produces a mathematical method or trajectory for the subject of class VIII number patterns that are valid and reliable. Valid from HLT and traceable. Reliability is seen in data triangulation, namely from field notes, observation sheets, and video recordings. Where by using magnetic cube media that combines using STEM students are happier and excited in learning because they use knowledge, technology from the media, their ability to use media so that it brings out the expected mathematical knowledge
Mathematical and Mental Rotation Skill in Internal Representation of Elementary Students
Authors: Fiantika Feny Rita
Published: February 2021

In this article, we review how the mental rotation of students in their internal representation and what is mathematic skill they used. Researchers found three geometry problems in elementary schools in Kediri Indonesia. Students have difficulty to make a cube net from the cube and they have opinion that to make a cube they need parallelogram and square. It is a big problem in geometry to transform 2 dimensional objects to 3 dimensional objects and vice versa. Based on the geometry problem of student in Kediri Indonesia, the researcher gives them a cube to modify as a cube net. Internal process is activities in their mind that they used for make a transformation an object into another object. The form of an object is different in this case 3 dimensional object into 2 dimensional object. They used mental rotation in transformation process. This article describes process mental rotation and mathematic skill student that they used to transform 3 dimensional object to 2 dimensional object. The result shown that encoding of features, imagined angular stimuli rotations and fast stimulus matching are they used in mental rotation processes and they used symbolic number sense, ordinal magnitude sense and line sub division are they used in mathematic skill.
An Analysis of Mathematical Communication Ability on Solving Open Ended Problems in Linier Equation System with Two Variables
Authors: Anwar Rivai M , Mardiyana  , Slamet I
Published: February 2021

Mathematical communication ability are the ability of students to convey mathematical ideas either orally, in writing or in motion, so that mathematical communication ability must be possessed by students. This research is a qualitative descriptive study that aims to describe the mathematical communication ability of junior high school students in solving open ended problems, namely where one problem has many solutions or many ways of solving. The subjects in this study were 28 students of class IX of SMP Negeri 1 Mojolaban and the instruments used were 3 test descriptions of mathematical communication ability test. The variable of this study is an indicator of mathematical communication ability. The results show that students’ mathematical communication ability are quite well categorized, with the following details: student achievement in expressing real objects, situations and daily events in the form of mathematical models as much as 91.6%, student achievement in explaining mathematical ideas and models into ordinary language as much as 69.6% and student achievement in explaining and making mathematics questions learned as much as 40.47%. From the three indicators, it appears that students are still lacking in terms of explaining and making mathematical questions learned.
Assessment of Students’ Mathematical Proof Comprehension: Gender and Year Level Background
Authors: Waluyo Mohamad , Vidákovich Tibor
Published: February 2021

The ability to understanding proof is essential before students can write their proof. A literature study shows a few interests in investigating the students’ knowledge from reading proof. This study aims to assess students’ comprehension when they were reading proof using a developed instrument based on the previous study on the same field. Three groups of students from a different level of years from a preservice teacher training program in an Indonesian university are taken as the participants. This paper reports the preliminary finding of students’ comprehension score comparison by gender and year level. Further analysis also involved the correlation of students’ basic knowledge to their comprehension scores.
Geometric Thinking Skills of Seventh Grade Students on the Topic of Triangle and Quadrilateral Based on Van Hiele Geometry Learning Theory
Authors: Nusaibah Naja , Pramudya I , Subanti S
Published: February 2021

Students’ geometric thinking skills can describe students’ understanding of geometrical concepts. According to van Hiele, students’ geometric thinking skills is divided into five levels, namely Level 0 Visualization, Level 1 Analysis, Level 2 Informal Deductive, Level 3 Deduction, and Level 4 Rigor. The level of students’ geometric thinking skills be an indicator of the success of learning geometry. The teacher should be able to analyse the students’ geometric skills to help students to improve their geometric thinking skills. The purpose of this study was to describe the geometric thinking skills of 7th grade students of Junior High School in Boyolali, Indonesia. This type of research was quantitative descriptive research. The study was conducted by giving ten questions that correspond to the level of students’ geometric thinking skills. The results showed that as many as 26.09% of students were at level 0, as many as 56.62% of students were at level 1, as many as 17.39% of students were at level 2, and no students were able to reach level 3.
Same pattern, different visualization: visual support does matter in pre-algebra
Authors: Apsari Ratih Ayu , Sariyasa  , Putri R I I , Rejeki S , Lu’luilmaknun U
Published: February 2021

This paper is a part of a more significant study in design research aimed to create a learning trajectory in pre-algebra. The study was following the steps of the Preliminary Study, Teaching Implementation and Retrospective Analysis. In the current discussion, we will focus on the importance of visualization employed to represent the specific number pattern. The study was conducted in a state elementary school in Palembang with eight fifth grade students who participate during the Teaching Implementation phase. We gathered data from students’ written work, interviews, and observation during the lesson. The data were analyzed qualitatively using the constant comparative method. From the analysis, it was found that even though the problems were using the same number pattern, the students’ interpretation that leads to a correct generalization were highly influenced by the visual support. Hence, it is recommended to the future learning materials designers and teachers to consider the visual support matters to enhance the students’ mastery.
Digital technology in learning mathematical literacy, can it helpful?
Authors: Novita Rita , Herman T
Published: February 2021

Literacy is a critical skill and is quite a concern in the world of education, especially mathematics education in the 21st century. Literacy in mathematics illustrates how a student identifies and understands the problems in which mathematics he has learned plays a role in all aspects of life. On the other hand, the 21st-century digital era demands the realm of education to be able to utilize ICT (Information and communication technologies) in the learning process, not least in mathematics. Digital technology, as a tool that is believed to make a significant contribution to the development of education, is also a challenge in its application, especially concerning the development of mathematical knowledge and skills, mathematical literacy. A question that arises is, can the use of digital technology develop mathematical literacy in the process of learning mathematics? If the answer can, then how should such integration be carried out. This article aims to provide an overview of the answers to these questions by giving an overview of the importance of mathematical literacy and digital technology in developing mathematical literacy.
Science, Mathematics, Engineering, and Mathematics (STEM) Education in Indonesia: a Literature Review
Authors: Khotimah Rita Pramujiyanti , Adnan Mazlini , Ahmad Che Nidzam Che , Murtiyasa Budi
Published: February 2021

This study aims to describe: 1) the learning models used in the implementation of STEM education in Indonesia, 2) the level of education used in the implementation of STEM education in Indonesia, 3) the effect of STEM education in Indonesia on the students’ learning outcome. This is a literature review study, 27 articles were analyzed based on the research method, level of education, learning models, and learning outcome. A within-case analysis was carried out to analyze the articles in the dataset. The research result showed that: 1)STEM education in Indonesia was carried out by using the learning models: Project Based Learning (PjBL), 6E, HOTS assessment based-learning, inquiry,Think Pair Share (TPS), Problem Based Learning (PBL), android game, digital and student book based-learning, PjBL is the learning model which most widely used in the implementation of STEM education in Indonesia, 2) STEM education in Indonesia was conducted in elementary school, junior and senior high school, but very limited in university level, 3) STEM education in Indonesia was effective on the students’ learning outcome: scientific literacy, creative thinking, critical thinking, attitude, HOTS, character, achievement, problem solving, and 21st century skill.
The Analyzing of Pisa-based Mathematics Problem Solving Ability based on the Algebra Learning Object
Authors: Sumardi  , Herawanto Muhammad Risal
Published: February 2021

The aim of this study was describing the ability in solving math problems based on PISA change and relationship content based on algebra learning objects. This research was descriptive qualitative study involving 28 students of VIII B class at SMP Negeri 25 Surakarta. The techniques of collecting data used tests and interview, while the techniques of analyzing data were using data reduction, presentation, and drawing conclusions. The results of this study was the students’ problem solving abilities based on four algebra learning objects according to Skemp’s view, namely: 1) using symbols, 2) mathematical models, 3) linear equations and their solutions, and 4) algebraic calculations. The students with high-level math abilities were able to apply four algebra learning objects, namely: using symbols, making mathematical models, linear equations and solving them well, and the calculations correctly. The student’s weaknesses was not accurate in writing on the result of the unit obtained and there were no several symbols in giving information. The students with mid-level math abilities were only able to use symbols and create math models, the writing of the linear equations was correct but the solution was still incorrect because it was like Polya’s stage, so it was not quite right because there are no calculation steps. The students with low-level math abilities were only correct in writing linear equations, the way of solving and calculating the problems were still incorrect, and the writing of mathematical models and using symbols were incorrect.
The development of student worksheets based on higher order thinking skill for mathematics learning in junior high school
Authors: Sutama  , Prayitno Harun Joko , Narimo Sabar , Ishartono Naufal , Sari Diana Purwita
Published: February 2021

There are three purposes of this study. 1) to develop student worksheets based on Higher Order Thinking Skills (HOTS); 2) to test the feasibility of developed student worksheets, and 3) to analyse student assessments of developed worksheets. This research is a research and development (R&D). The development model is ADDIE which consists of 5 stages, namely Analysis, Design, Development, Implementation, and Evaluation. The study was conducted at SMP Negeri 1 Karanganyar in the academic year of 2018/2019. Data collection was obtained through observation, interviews, documentation, and questionnaires. Data analysis techniques used was critical analysis and comparative descriptive analysis. The results of the research were 1) This research and development had produced a worksheet based on HOTS on the subject of algebra; 2) Student worksheets developed were declared valid by experts and education practitioners, and 3) The results of the students’ responses showed that the student worksheets that had been developed were interesting and the questions of HOTS presented were quite challenging to solve. Thus, students’ worksheets based on developed HOTS were suitable to be used in mathematics learning.
Ethnomathematics Vs Ethomodeling: how does cigugur traditional community determines the direction of the wind to seek fortune based on month
Authors: Umbara Uba , Wahyudin  , Prabawanto Sufyani
Published: February 2021

This study discusses the way of Cigugur indigenous communityin predicting the direction ins seeking fortunes. It uses a phenomenological approach with a realist ethnographic design through observation techniques, in-depth interviews, documentation, and field notes. The findings of this study indicate that the system of knowledge and livelihood which are included in the universal element of culture are implemented by the community using formal mathematical principles. Ethnomathematics as a research genre tries to reveal the dimensions of basic universal mathematical activities, while ethnomodeling as a methodology is used to represent the ideas and practices of community mathematics into academic mathematics through ethical, emic and dialctical approaches. The combination of naktu weton lahir, naktu pasaran, naktu tahun and naktu bulan, the time of one’s birth month can be used to predict a good direction in seeking fortune. Based on the study of ethnomathematics, the community determines the direction in seeking fortune, the mathematical concept used by the traditional Cigugur community is the concept of sequential pairs, relations, summations, and comparisons. Meanwhile, based on ethnomodeling, the community uses the concept of modulo and congruence. Ethnomatematics and ethnomodeling provide a different perspective on the conceptual mathematics that is inherent with the universal element of holistic culture.
Reflective thinking process of students in completing mathematical problems based on mathematical reasoning ability
Authors: Tisngati Urip , Genarsih Tunjung
Published: February 2021

This research aimed to describe the reflective thinking process of eighth-grade students of junior high schools in solving mathematical problems of circle material based on mathematical reasoning. It was a qualitative descriptive with a case study approach. There were 6 subjects selected by using purposive sampling technique based on mathematical reasoning levels. The methods used were test, interviews, and documentation techniques. The results showed that students with high mathematical reasoning level were able to fulfill all indicators of the reflective thinking process including identifying facts and questions, explaining the operations to be chosen, carrying out plans, and giving logical conclusions with indicators students wrote the correct final answers based on the order of the previous problem solving process; students with medium mathematical reasoning fulfilled two to three indicators of identifying facts and questions, explaining the operations to be chosen, carrying out a problem-solving plan; students with low mathematical reasoning fulfilled an indicator of identifying facts and questions; students tend to experience errors in the calculation aspects, lack of students’ prior knowledge, understanding, and mathematical attitude. It was concluded that there is a connection between problem solving and mathematical reasoning with reflective thinking ability of students. It have implications for teachers to condition mathematics learning by paying attention to students’ thinking skills.