bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of BaCO3 addition on critical temperature of Bi-Pb-Sr-Ca-Cu-O superconductor
Authors: Akbar I A , Imaduddin A , Humaidi S , Nugraha H 
Published: May 2021

Abstract
Bi-Pb-Sr-Ca-Cu-O high temperature superconductor has been applied in the field of electricity as power transport cables. This work has been carried out to investigate the effect of addition of BaCO3 on Bi1, 6Pb0, 4Sr2Ca2Cu2O10 superconductors. Solid state reaction method was used to prepare all samples. The starting materials were Bi2O3, PbO2, SrCO3, CaCO3, CuO, and BaCO3 powder. Starting materials without BaCO3 were ground using a mortar agate for 3 h. After calcination process of 820°C for 20 h, samples were mixed with BaCO3 (1 %wt, 2 %wt) and then sintered by 850°C for 30 h. Characterizations ware conducted by using cryogenic magnet to determine the critical temperature (Tc), SEM-EDX to analyze morphology, and XRD to determine the phase formed. There were semiconductor properties at high temperature and it was found that the addition of BaCO3 decreased Tc of the samples. 1 %wt BaCO3 showed a critical temperature with Tconset = 86 K and Tczero = 52 K, and 2 %wt of BaCO3 has Tconset of 80 K, and Tczero of 23 K. The surface morphology contains agglomeration and there is a lot of porosity. The dominant phase formed is Bi(Pb)-2212 with a volume fraction of 64.71%.
Forecasting sea surface temperature anomalies using the SARIMA ARCH/GARCH model
Authors: Oktaviani F , Miftahuddin  , Setiawan I 
Published: May 2021

Abstract
The areas that are close to the Indian Ocean can give a significant impact on climate change that caused by SSTA. Based on the records from NOAA website, there are data about points in the Indian Ocean. Moreover, climate change on earth is influenced by several parameters, one of them is called SSTA. Therefore, it is necessary to forecast SSTA in the future to minimize the impact of climate change. With a purpose to predict data that contains seasonal patterns, the method that can be used is SARIMA method with ARCH or GARCH. This study aims to determine the results of SSTA forecasting for the period from August to December 2018. This study uses the 4°N90°E point, which is a point located close to Aceh Province. The data used are daily data obtained from the NOAA website, from July 2010 to July 2018. Based on the research results, the best model for SSTA forecasting is the SARIMA model (2, 1, 1)(0, 1, 1)-GARCH(1, 1) with forecasting accuracy values of 3.67% MAPE, 0.032 MAE, and 0.016 RMSE. The MAPE values that are smaller than 10% indicate that the SARIMA (2, 1, 1)(0, 1, 1)-GARCH(1, 1) model is very good for forecasting SSTA in the future.
High school Physics teachers’ perceptions of the learning revolution era 4.0 at training activities in Bener Meriah Regency
Authors: Elisa E , Farhan A , Herliana F , Wahyuni A , Susanna S 
Published: May 2021

Abstract
The constraints of the limited practicum facilities for Physics lessons in Bener Meriah Regency High School schools can be overcome by virtual laboratory practicum. Learning technology using a virtual laboratory experiment method based on Smart Phone is given to Physics teachers in the district so that they can use simple information technology applications in learning. The subject matter of physics used in this training was Waves and Optics. This activity is gradually carried out to pioneer the realization of physics learning in high schools following the demands of the industrial era 4.0. The output is expected to improve the pedagogical quality of teachers, the learning process, and to overcome the limitations of Physics practicum tools, and to support online learning during the Covid-19 pandemic. The activity was attended by 10 high school teachers in Bener Meriah Regency. All participants were able to master the transfer of technology provided. They are optimistic that this IT technology can be implemented in the learning of Wave and Optical material Physics in their schools on duty. 100% of trainees are satisfied with the service and expect will be any similar activities to be continued for other Physics materials.
Computing the auto regressive distributed lag (ARDL) method in forecasting COVID-19 data: A case study of NTB Province until the end of 2020
Authors: Negara H R P , Syaharuddin  , Kusuma J W , Saddam  , Apriansyah D , Hamidah  , Tamur Maximus 
Published: May 2021

Abstract
The purpose of this research is to conduct data forecasting on the spread of COVID-19 in West Nusa Tenggara Province, Indonesia at the end of 2020. The data used in this research is the COVID-19 data in NTB Province including the data of the number of positive patient, the number of patients recovered and the number of patient passed away. The forecasting process uses the Autoregressive Distributed Lag (ARDL) method of the GUI Multiple Forecasting System (G-MFS) based on MATLAB by determining the prediction on the next day of the graph equation generated after the data simulation. The forecasting of the COVID-19 spread in NTB at the end of the year of 2020 obtained that the number of confirmed patients amounting to 19, 614 people with an average increase of 1.48%, the number of patients healed are 6, 651 with an average increase of 1.10%, and the number of patients died amounting to 4, 953 people with an average increase of 2.42%. The average increase in the number of patients who died showed that the provincial government of NTB needs to give more serious attention to handling COVID-19 patients.
Efforts to improve students’ mathematical critical thinking ability by using Team Assisted Individualization learning model
Authors: Marasabessy R , Hasanah A , Angkotasan N 
Published: May 2021

Abstract
The development of critical thinking is the goal of the Indonesian education curriculum. However, research on how to develop and improve these abilities is still rarely studied. In this article, we offer a team assisted individualization-learning model in improving critical thinking skills. The objectives of this study were (1) to describe the improvement of students’ mathematical-critical thinking skills using the Team Assisted Individualization learning model, (2) To determine the increase in students’ critical thinking skills after team assisted individualization learning has carried out. This study used experimental research. The subjects in this study were fourth-semester students of the Khairun University mathematics education program. The instrument used was a question describing students’ mathematical-critical thinking skills. Data have been analyzed per indicator and as a whole using descriptive analysis, namely benchmark reference guidelines (PAP) scale five and Normalized Gein. Data were analyzed using the inferential analysis to determine the increase in students’ mathematical critical thinking skills, namely hypothesis testing (one-sample t-test). The result of the data analysis showed an increase in students’ mathematical critical thinking skills, which were interpreted moderately after implementing the assisted individualization team learning model.
The impact of students’ personality types on the application of problem-solving strategies in solving PISA questions
Authors: Mawaddah A , Anwar  , Yusrizal  , Zubainur C M 
Published: May 2021

Abstract
The problem-solving strategy is one of reasons why Indonesian students competing in PISA only placed at the lowest rank. This is caused by some factors, including personality types. To indicate the effect of these types towards students’ strategies used is required more detail explanation. This research aims at investigating the strategies used by students in solving PISA questions based on personality types. There were 30 junior high school students in Banda Aceh involved in this research. Two research instruments were used, one consists of level 4, 5, and 6 PISA questions and another one is the Myers-Briggs Type Indicator questioner. The data gathered were analysed by grouping students based on the Myers-Briggs types. Afterwards, students’ answers to PISA questions were matched with the ten indicators of Posamentier and Krulik’s problem-solving. The result of this research shows that students come under 6 of 16 personality types. The result indicated that personality types impact the strategies which students applied in solving a problem in answering PISA questions. The implication of this study shows that teachers require to use combination of problem solving strategies to address different types of students’ personalities in Mathematics teaching and learning processes in order to optimize students’ achievements, particularly in problem-solving.
Mathematical communication skills in solving block and cube problems
Authors: Zulhelmi  , Anwar  
Published: May 2021

AbstractMathematical communication skills are required for understanding the lessons given by teachers. Students’ low mathematical communication skills are due to their lacking participation in learning or they are rarely allowed to ask or express their opinions. Learning process is still only the teachers teaching in front of the classroom and assigning tasks to students resulting in mathematical communication skills have not been able to be conveyed properly. This research aims to describe students’ written mathematical communication skills in solving cuboid and cube problems and to find out factors that influence mathematical communication skills. The research was descriptive means it explained and described students’ mathematical communication skills based on their indicators. The methods used were tests and non-test to see the students’ ability and to observe how students expressed opinions based on the answers they have written. The results showed that the problems faced by moderate and low ability students related to aspects of writing and drawing and the difficulty of expressing mathematical ideas. Highly qualified students had fulfilled all aspects of mathematical communication skills, namely writing, drawing, and mathematical expression in presenting mathematical ideas in solving math problems.
Guiding children in learning subtraction by using contextual strategy: as an attempt to develop students’ number sense
Authors: Novita R , Herman T 
Published: May 2021

Abstract
Subtraction operations are basic number operations that have been introduced to students at the 2nd grade of elementary school. Several studies have shown that this topic is difficult for students to understand and causes many problems in learning of numbers. Students’ constraints in performing this subtraction operation usually occur when subtracting two numbers in tens, hundreds, or more or numbers containing 0. One of the procedures that teachers often teach students in solving the problem of subtracting two numbers is borrowing techniques. This technique is often seen as forced and very abstract to students. This study aims to describe how students thinking in performing subtraction on numbers through more contextual strategies that they understand. This study used a single-subject research design with multiple baselines across individuals (n = 2) to evaluate the effectiveness of the measures performed. The intervention observed in this study was to use the number of subtraction technique with a different contextual strategy between the two subjects. The results indicate that the two contextual strategies used show a positive effect on understanding the number subtraction operation. The results also showed that subtraction without borrowing (not using formulas) made students more creative in solving the subtraction problem.
Development of student worksheets on ethnomathematics-based trigonometry through Project-Based Learning models
Authors: Husna N , Saminan  , Abidin Z 
Published: May 2021

Abstract
One of Indonesia Curriculum 2013 learning principles is learning that prioritizes culture and the empowerment of students. The culture of certain societies contains a mathematical concept known as ethnomathematics. One of the many mathematical materials found in ethnomathematics is trigonometry. However, in reality, students have difficulty mastery of trigonometry material. So far, ethnomathematics-based learning tools in Aceh traditional houses as an application of trigonometry are not yet available. Therefore, it is necessary to develop ethnomathematics-based learning tools. This study aims to develop an ethnomathematics-based trigonometry project worksheet through the Project-Based Learning model that met the valid criteria. This research refers to the Plomp development model, which consists of preliminary research and a prototyping stage. This study’s instruments were needs analysis sheets, validation sheets, observation sheets, and response questionnaires. The results showed that the developed Project Worksheet met the valid criteria because all validators stated that the project worksheet was fit for use.
Students’ mathematics problem solving ability through Model Eliciting Activities (MEAs)
Authors: Wahyuni S , Dahlan JA , Juandi D 
Published: May 2021

Abstract
Mathematical problem solving is an ability that is needed in the real world, especially in the field of work. Therefore, it is necessary to hone these skills from an early age. This study aims to describe the mathematical problem-solving abilities of students who learn to use MEAs. This research was conducted in class VIII at a junior high school in Bandung, Indonesia. The research method used is a qualitative approach. The instrument used was a test of mathematical problems solving and interviews. The results showed that the description of the mathematical problem-solving abilities of students who learned using MEAs, namely low category students succeeded in getting to the simple problem-solving planning stage so that the solving steps were not correct. Students in the category of being successful in problem planning but mistakenly seeing the facts in the problem, so that mistakenly made the first stage mathematical model so that students were wrong in determining the final goal of the solution. High category students succeed at the completion plan implementation stage of making the first stage mathematical model but mistakenly consider the real-world situation after the mathematical model at a later stage.
The effectiveness of the Project-Based Learning (PjBL) model in students’ mathematical ability: A systematic literature review
Authors: Yunita Y , Juandi D , Kusumah Y S , Suhendra S 
Published: May 2021

AbstractOne of the learning models recommended in the 2013 Curriculum is Project Based-Learning (PjBL) model with the demands for the skills required in the 21st century. This learning model can be applied to enhance students’ mathematical ability. This study aims to determine and evaluate the effectiveness of the PjBL model process to foster mathematical ability. This study used a systematic literature review method, including planning, implementing, and reporting. The data were analyzed based on data inclusion criteria, and then the data were extracted, resulting in 26 studies. The findings indicated that an increase in mathematics abilities through mathematics learning using PjBL could occur if students are directly involved in the learning process with clear directions, and they pay attention to essential aspects, such as learning activities, optimal use of time, and mathematical ability. Another finding revealed that the large percentage of the number of studies discuss the influence of the PjBL model on problem-solving and creative thinking skills. There is also an increase in publications, especially those indexed by Scopus every five periods and many studies using random research sampling. Thus, the PjBL model is appropriate for achieving learning objectives, especially in mathematical ability.
Students’ thinking process in solving Higher-Order Thinking (HOT) problems through Aptitude Treatment Interaction (ATI) learning model
Authors: Hanum O , Johar R , Yusrizal  
Published: May 2021

Abstract
The assessment model in the 2013 Curriculum has adapted the international standardized assessment model. It is expected to help students to improve their higher-order thinking skills. One of the differences among students that teachers should pay attention to is their thinking process when solving math problems. The Aptitude Treatment Interaction (ATI) learning model is a learning model that adapts learning to the characteristics of students’ abilities. The purpose of this study was to investigate how high-, moderate-, and low-ability students could solve higher-order thinking (HOT) problems through the ATI learning model. This research employed mixed methods. The participants were students of Junior High School 3 Banda Aceh, in which three of them were interviewed. The data were obtained from observations, tests, and interviews. The results showed that the ATI learning model did not directly impact the students’ thinking process in solving HOT problems. Instead, it had a profound effect on students’ activities during the study. The high-ability students were better than the moderate- and low-ability students in each indicator of the thinking process in solving HOT questions. Students’ activities increased during the learning process from the first meeting to the last one.
Didactical design of vectors in mathematics to develop creative thinking ability and self-confidence of Year 10 students
Authors: Adharini D , Herman T 
Published: May 2021

Abstract
This research was motivated by the low ability of creative thinking in mathematics and students’ self-confidence. This study aims to compile a didactic vector mathematical design to develop students’ creative thinking skills and self-confidence. This type of research is Didactic Design Research (DDR). The participants were 50 Year 12 students and 24 Year 10 science students. Data collection on learning obstacle was carried out on Year 12 students using tests, interviews, and textbook analysis. It was found that most students had didactical obstacles. Students had low creative thinking ability, and students with mathematical skills low had low self-confidence. The didactic design was implemented online twice for Year 10 students using the zoom meeting application and google classroom. Students’ creative thinking skills develop well for questioning and guessing and product improvement. Most of the students’ self-confidence is in good condition. Further research should provide an explanation of the related material before the test, make a didactic design using e-learning, add formulas for student activities, and provide examples and explanations for each completion step.
The Development of a rapid method for Plutonium separation by extraction chromatography and its application for environmental samples
Authors: Khairina R , Giyatmi  , Makmur M , Kusdiana  
Published: May 2021

Abstract
This research aims to develop a rapid method of plutonium analysis from sediment samples using the extraction chromatography method with TRU resin. This approach will be compared with the anion exchange method with DOWEX resin previously conducted in the BATAN radioecology laboratory. Plutonium measurements was carried out using an alpha spectrometer with a PIPS detector after the separation processes. The results showed that recovery using extraction chromatography followed by the microprecipitation method resulted in an average recovery of 71.22 percent, compared to anion exchange using the electrodeposition method, which obtained about 58.89 percent. Since a combination of chromatographic extraction with electro-deposition, the recovery is still low, about 27.56 percent. The chromatographic extraction method with microprecipitation method to sediment samples from the coast of Merak resulted in an average activity of 0.14 Bq/kg dry. The activities obtained are comparable with the previous data from the Merak coastal sediment study. The advantages of using the extraction chromatography method compare to using the anion exchange method to separate plutonium from sediment samples are the shorter separation time and the less acid waste produced. Another advantage is that it is more selective to separate plutonium from other actinides. This approach is very suitable for emergency preparedness when there is an emergency response.
Magnetic Sulfonated Chitosan composite beads for Mercury removal from Aqueous solutions
Authors: Lelifajri  , Rahmi  , Ayu A S W 
Published: May 2021

Abstract
Magnetic sulfonated chitosan composite beads had been prepared and applied for mercury removal from aqueous solutions. Preparation of magnetic sulfonated chitosan composite beads was initially performed by the sulfonation of chitosan and continued with the addition of iron oxide particles prepared from local iron sand to form composite beads. The magnetic sulfonated chitosan beads were characterized by FTIR and XRD analysis. FTIR spectra confirmed the formation of magnetic sulfonated chitosan beads. The patterns of XRD exhibited the decrease of chitosan crystallinity after modification. The result of adsorption experiments showed that the addition of sulfonation and iron oxide particles can improve the adsorption capacity of chitosan.
Phytochemical screening and spectrum profile of functional group from Banana (Musa paradisiaca L.) stem waste extract using Fourier-transform Infrared (FTIR) Spectroscopy method
Authors: Purnama R C , Primadiamanti A 
Published: May 2021

Abstract
Banana (Musa paradisiaca L.) is plant that contain secondary metabolites compounds such as tannins and flavanoids. Tannins and flavanoids have various properties for human health. Research had been conducted to identify secondary metabolite compounds (tannins, flavanoids, and saponins) with phytochemical screening methods and to look at the spectrum profile of the functional group found in the waste extract of banana stem. The waste of banana stem extracted with 96% ethanol. From the obtained extract, evaporation and phytochemical screening were carried; consecutively. From the screening results, tannin compounds were characterized by a greenish-black result, and flavanoids created a deep red color. Saponins were expressed negatively because the formed foam had a height of 0.3 cm and did not meet the requirements of saponins expression (foam height 1-3 cm and stable for 5 minutes). After that, the identification of the functional group found in the banana stem waste extract was carried out using Fourier-transform Infrared (FTIR) spectroscopy. Banana stem waste obtained the form of compound function clusters supported by o-H bound absorption data in the area of 3284.91 cm-1, c = O in the area of 1643.06 cm-1, bend CH2 in the area 1409.25 cm-1, and C-C in the area 1078.56 cm-1.
Scale-up preparation and testing of activated-carbon-cloth as carbon-filter prototypes for ammonia-vapor adsorption
Authors: Adlim M , Rahmayani R F I , Zarlaida F , Yudha M B 
Published: May 2021

Abstract
This study is a scaled-up experiment for carbon cloth made of the pristine-palm-kernel shell studied previously at the laboratory level. Prototypes of activated carbon filter (cylindric net, 40 cm height & 18 cm diameter) were prepared from the activated palm-kernel carbon cloth. The ammoniac adsorption capacity test was carried out within six closed rooms with the individual dimension of 120 cm × 90 cm × 220 cm. The ammonia vapor samples were determined by UV-Vis spectrophotometric method. Each room contained 2.8 × 10−5 M of ammonia vapor at ambient temperature, (28 + 1)°C atmospheric pressure. The activated carbon mean-weight of (179 + 5) g or equivalent to (0.1 + 0.003) g per cm2. The optimum time of adsorption was 60 minutes and the mean adsorption capacity of the carbon filter was 1.78 × 10−5 M per 1720 cm2 of carbon cloth. The carbon filter prototype absorbed 60.6% of ammonia vapor in the closed room. The adsorption remained constant, although the absorbent and time were expanded.