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NanoHydroxyapatite/chitosan (Cs) composite material has been successfully synthesized by the co-precipitation method. The Hydroxyapatite (HAp) was synthesized by utilizing limestone in Druju Malang, East Java, as a source of calcium using the co-precipitation method. XRD characterization resulted in HAp crystal size 23.13 nm, and EDX characterization results showed a Ca/P ratio of 1.64. Variations in the pH of the solution with values 4, 7, and 13 were carried out on the synthesis of nanoHAp/Cs composites. At pH 4 (acid) for samples with sintering showed a significant increase in hardness compared to those without sintering from 14.28 to 177.87 kg/mm2. Acid pH conditions increase the hardness of the composite significantly. Therefore, the choice of reaction pH is worth consideration. [ABSTRACT FROM AUTHOR]

A novel PVA/TiO2 nanofibers composite membranes that can be used for photocatalytic applications are synthesized by electrospinning methods. These new nanofibers membranes are prepared by better processing of the electrospun solution with the addition of sonication and surfactants. PVA/TiO2 composite nanofibers were observed by the characterization of SEM, EDAX, and FTIR. The characterization results showed the PVA/TiO2 composite nanofibers membranes have a good performance of photocatalytic. FTIR results showed functional PVA groups, and EDAX results showed TiO2 successfully inserted into the nanofibers membrane. The effects of processing with certain treatments, such as sonication and surfactant addition to the morphology and photocatalytic properties, were studied in the experiment. EDAX characterization shows that nanofibers with sonication have a TiO2 distribution along with an increase in the percentage of TiO2 up to 10.20%. This indicates that sonication can increase the electrospun solution to be more homogeneous. Nanofibers, with the addition of surfactants, have better TiO2 distribution, along with an increase in the percentage of TiO2 to 16.21%. The dye degradation ability of the PVA/TiO2 composite nanofibre membrane was investigated by the methylene blue photodegradation test under UV light. Methylene blue degradation was measured by UV vis spectroscopy. The photocatalytic activity of the PVA/TiO2 composite nanofibre membrane reduced Methylene Blue up to 40%. Sonication treatment increases photocatalytic activity by up to 60%, and the addition of surfactants increases photocatalytic activity by up to 80%. [ABSTRACT FROM AUTHOR]

Students' ability in scientific argumentation is very important to improve the skills needed in studying physics, especially thermodynamics. However, students' scientific argumentation skills in thermodynamics are still not optimal because they seem abstract. Authentic learning is needed where thermodynamic phenomena occur in our lives. Meanwhile, authentic problem based learning (aPBL)-STEM solutions with formative assessment to overcome low scientific arguments are still rare. This study aims to explore students' scientific argumentation skills on the subject of Thermodynamics through aPBL-STEM with Formative Assessment. This study uses a mixed method with embedded experimental design and research samples were 33 students of class XI science in Waikabubak, Indonesia. The instrument used is the Thermodynamics' Scientific Argumentation Test in the form of 5 essay test items with a reliability of 0.728. Quantitative analysis based on pretest and posttest data using Wilcoxon test, N-gain, and effect size. Qualitative data on variations in student answers, results of interviews and observations, were analyzed by reducing data, coding, and conclusions. The results of students' answers are categorized into five levels of scientific argumentation, namely very weak, weak, strong enough, strong, and very strong. The results showed that there was a significant increase in students' scientific argumentation skills, with N-gain = 0.51 (medium category), and effect size = 2.84 (strong category). The average level of students' scientific arguments is strong enough. In addition, students still have difficulty in determining the work on the system, analyzing PV graphs, the efficiency of Carnot engine, and understanding the entropy concept. In future research, it is better to train students specifically to write the rebuttal component and add to the control class. [ABSTRACT FROM AUTHOR]

Nanofiber PVA/Chitosan/TiO2 have been prepared by electrospinning method. Electrospinning was performed at a voltage 15 kV, with a tip-collector distance of 14 cm. A novel nanofibers mat was fabricated in various contents of PVA, Chitosan, and TiO2. The structure of PVA/Chitosan/TiO2 was examined by FTIR, XRD, and SEM-EDAX. The results showed that PVA/Chitosan/TiO2 nanofiber was successfully formed. SEM observation showed that the fiber had several hundred nanometers with a smooth surface and distributed randomly. It was also observed that nanofibers containing chitosan show smaller diameter than that of without chitosan. The beads on the nanofibers are decreased by adding TiO2 nanoparticles into the electrospun solution. [ABSTRACT FROM AUTHOR]

Ceramic/polymer composites are currently being developed by researchers because of their wide applications in biomedical. This work describes the synthesis of hydroxyapatite/polyethylene glycol (nHAp/PEG) composites by the co-precipitation method with a composition ratio of 80:20 wt% and temperature variations of 25, 50, 75 °C. HAp was synthesized from limestone using the co-precipitation method. The properties of HAp and nHAp/PEG composites were evaluated using XRD, SEM, EDX and hardness that was tested by Vickers hardness. Synthetic HAp has a crystal size of 28.89 nm. The co-precipitation temperature affected the porosity and hardness of the nHAp/PEG composites, respectively for porosity of 2.98, 5.88, 8.82% and for hardness of 0.07, 0.05, 0.04 GPa. SEM results show a microstructure with a narrow grain size distribution, which means it is almost homogeneous. Hardness values in the range 0.04-0.07 GPa are appropriate for dentin applications. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) nanostructures are known to contribute a straight pathway for electron transfer to achieve good device performance. Besides that, Titanium dioxide (TiO2) is a metal oxide semiconductor, investigated as a material with upstanding physical and chemical properties with excellent light sensitivity, good relialibility in the environment, and low synthesis costs. In this research, the composite of ZnO nanorod/TiO2 designed to become a semiconductor coating material for photoanodes to support the process of electron transport. In this research, hexagonal structures of ZnO nanorods were synthesized by various growth time of hydrothermal synthesis method. The growth time affects to ZnO nanorods was systematically investigated on ZnO nanorods/TiO2 composites by scanning electron microscopy. From the XRD analysis showed that the ZnO nanorods in a crystalline phase in ZnO nanorods/TiO2 composites. Its crystallinity increases with increasing hydrothermal duration. In addition, the hydrothermal duration of 5 hours resulted the largest diameter and thickness of ZnO nanorod. [ABSTRACT FROM AUTHOR]

In science learning, it is important to develop procedural and conceptual understanding, one of which is to train students' science process skills (SPS) in the classroom. SPS is very important for every student because it underlies students' ability to train thinking such as formulating hypotheses, conducting experiments and analyzing data. The fact is that SPS is still not optimally implemented during the learning process and is still rarely trained to students. The purpose of this study was to create the profile of students' SPS which includes basic SPS and integrated SPS on thermodynamic topics through authentic PBL with STEM approach and formative assessment. This study uses a descriptive analysis of the results of observations and student worksheets. The Indicators of SPS are categorized into four, namely very good (score 4), good (score 3), not good with (score 2), and very not good (score 1). The results of observations during the learning process showed that students' basic SPS had percentages above 68% and integrated SPS above 70.6% with both categories being good and very good. The SPS indicators that students tend to master well are classification indicators, while those that tend to be difficult are predicting. [ABSTRACT FROM AUTHOR]

The aim of this study was to fabricate an HAp/Zn-ferrite nanocomposite for drug delivery application. The HAp/Zn-ferrite nanocomposite was synthesized using the coprecipitation method. The nanocomposite obtained was then characterized using XRD, SEM, and FTIR. Meanwhile, the drug delivery performance of the synthesized nanocomposite was characterized with UV-Vis to determine the loading and releasing capabilities. The result of XRD data analysis showed that the HAp phase had a crystallite size of 10.0 nm with a hexagonal crystal system. The presence of a Zn-ferrite was detected with a cubic spinel system with a crystallite size of 13.4 nm. The results of the FTIR analysis showed that the presence of the HAp phase was indicated by the presence of PO43-, CO32- and O-H groups. Meanwhile, the Zn-ferrite phase was indicated by Fe-O and Zn-O vibrations. The surfactant element was detected by the vibrations of CH2, COO−, C-C, and O-H groups. Based on the SEM image, it was known that the aggregated particle size was 60 nm with spherical morphology in the form of granular. The result of the UV-Vis data analysis showed that the nanocomposite had the ability to load doxorubicin with a capacity of 27.61 mg/g and the ability to release doxorubicin, which was relatively stable, reaching 79.15% in 300 minutes. [ABSTRACT FROM AUTHOR]

Supercapacitor is able to provide fast charging rate, environmentally friendly and relatively abundant material availability. Manganese dioxide (MnO2) has a high potential to use as a supercapacitor electrode material because of its significant advantages compared to other metal oxides such as high specific capacitance due to the reversible redox reaction and affordable prices. Briefly, the experiment begins with the preparation of a composite solution with a variety of compositions that was deposited on the aluminum foil substrate as electrodes using the doctor blade method. The supercapacitor was packed in a coin cell with 1 M Et4NBF4. The symmetric supercapacitor cycled in the cell potential window of 0-2 V, exhibited excellent specific capacitance of 52.87 F g−1, with power density of 344.94 Wh kg−1 and maximum energy density of 21.84 Wh kg−1 with 82.23 % capacity retention for 100 cycles. [ABSTRACT FROM AUTHOR]

Supercapacitor has received considerable attention as a promising energy storage device due to its fast charging, excellent cyclic stability, and high-power density. Activated carbon is the main material used to make supercapacitor electrodes because it has a high theory-specific surface area reach of 2,685 m2g−1 and low cost. However, structure micropore activated carbon had poor ionic diffusion and transportability that make inefficient surface area utilization, long charge-discharge performance, and low cycle life. Therefore, continuous research is needed to improve supercapacitor performance by adding and modifying structure micropores to increase the performance of electrochemically active sites so that ionic diffusion is better. This research is focused on the influence of concentration PVP immersion 0 M and 0.06 M with the dehydrogenation method. The higher concentration PVP strongly influenced the microstructure, morphology, and electrochemical process. The activated carbon mesoporous was characterized by XRD, SEM – EDX, FTIR, BET, and Charge Discharge. Further, the supercapacitor with the best performance is shown by the highest concentration of PVP 0.06 M exhibited the highest specific capacitance, energy density, and power density of 83.83 F.g−1, 60.06 Wh kg−1, 454.24 Wkg−1. ACM-0.06 had highest cycle stability in the cell voltage of 0-2.4 V at a current density of 0.1 Ag−1, and maximum energy density is 58.96 Wh kg−1 with 95.82 % capacity retention after 25 cycles. [ABSTRACT FROM AUTHOR]

The design innovation and composition of TiO2 as a photoanode have been continuously studied in recent years to improve the photoconversion performance of Dye-sensitized Solar Cells (DSSC). The important components in the formation of TiO2 paste are solid content, solvents, and organic compounds as binders. In terms of solvents, water or simple alcohol are not suitable for screen printing methods, because cracking will occur after the annealing process by rapid evaporation. In this report, we investigated the addition of nitric acid (HNO3) and ethyl cellulose (CH2CH3) as a binder for optimize the overall DSSC performance. TiO2 photoanode was synthesized by screen printing method through the initial stage of making blocking layer with spin coating method. The effect of nitric acid and ethyl cellulose on, TiO2 powder was studied intensively to determine the best photoconversion performance. TiO2 films were prepared by varying the process without and with post-treatment. The XRD pattern confirmed the presence of a pure anatase phase of TiO2. The morphology of the photoanodes surface area were studied through SEM characterization. The characteristics of J-V shows an increasing in photocurrent and efficiency through the post-treatment process. DSSCs based on TiO2-HNO3 photoanode with post-treatment exhibited a highest efficiency of 3.59%. We found that the sample with post-treatment process have a smaller impedance than sample without post-treatment with charge transfer resistance (RCT) of 10 Ω and 23 Ω, respectively. It may indicate that the TiO2 film with post-treatment have a better interconnection then charge transfer and charge extraction process are more effective and resulting higher efficiency. [ABSTRACT FROM AUTHOR]

Nowadays, bone tissue engineering is developed rapidly along with better and faster healing needs. One application of bone tissue engineering is improvement in defects. This improvement was completed by regenerating the tissue through a skeleton called scaffold. In this study, nano-Hydroxyapatite (n-HAp)/PLA scaffold composites were successfully made with variations in composition. The basic ingredients for making n-HAp are from natural materials using the sonication method. Addition of PLA into the nHAp matrix was carried out with variations of 10, 20, 30, 40 and 50 wt%. Nano-HAp was characterized using XRD and SEM. n-HAp/PLA composites were characterized by SEM and porosity tests were carried out. The results showed the crystal size of HAp was 14.46 nm. The most optimal porosity test on composites with the composition of n-HAp: PLA; 90:10 wt%. [ABSTRACT FROM AUTHOR]

Material research for energy storage is increasing in an effort to find alternative renewable energy devices. A lot of thermal energy wasted in everyday life. Research for various alternative high-capacitance supercapacitor materials continues to be encouraged. SrTiO3 shows good electrical and dielectric properties, as wellas defect induced structure. Modification of local structure using Pb dopant on the SrTi1-xPbxO3 was applied for exploring the scientific information and its potential applications intensively. The synthesis of SrTi1-xPbxO3 was prepared by solid-state reaction method. The powder was then calcined, pressed into a pellet, and subsequently sintered at 860°C. Various fraction of lead (Pb) dopants were carried out in 0.00; 0.02; 0.04; 0.06; 0.08; 0.1 molar ratio. The structure, morphology, and supercapacitor properties of SrTi1-xPbxO3 composite powder was performed by using X-Ray Diffraction, UV-Vis, IV temperature-induced conductivity and CV EIS. XRD data analysis with Cu-Kα wavelength indicated the single phase was identified and a slight change in lattice parameters was observed. Sixfold symmetry of the local octahedral structure also changed to a tetragonal structure after introducing the amount ofPb element. For investigating electrical properties of SrTi1-xPbxO3, I-V meter was applied. Furthermore, electrical conductivity and dielectric constant will be discussed in detail. Loading higher Pb fraction promoted the electrical conductivity measured at various temperatures. Increasing conductivity is one indicator that this system potentially enhanced the electronic exchange of supercapacitor in SrTi1-xPbxO3 system. [ABSTRACT FROM AUTHOR]

Natural polymers can be extracted from leaf or stem of plants. Pterocarpus Indicus W. (PIW) and Jatropha Multifida L. (JIL) plants are good candidate as natural polymer sources. PIW and JIW polymers contain chemical compound so-called flavonoids which has C6-C3-C6 carbons conjugated configuration. The renewable type of polymer as well as their abundancy of flavonoid provide us to explore their physical properties. A number of research have been reported related to broad synthesis method and mechanical properties. So far there is no specific report of electrical conductivity associated to PIW and JIL natural polymers. In order to obtain electrical conductivity and its crystallinity of the extracted polymer films, it was induced on them a various fraction of silver nano particles. The film has been prepared by means of spin coating method on nickel substrate. It was revealed that FTIR spectra confirm the existing of rutine flavonoid. The crystallinity of the samples increase from 0.66%, to 4.11% associated to the respective various of silver fractions of 0.1 M to 0.5 M. SEM images show that there are some grains of silver in the film. The nature of electric conductivity increases a long with the addition of silver. The electrical conductivity increase significantly from 3.22 S/cm, to 542.85 S/cm. On the other hand, PIW films also shows similar trends that increase of Ag induce the increase its crystallinity as well as its electrical conductivity at semiconducting level. This result opens a prospective research and application of the green renewable polymer as optoelectronic materials. [ABSTRACT FROM AUTHOR]

Natural polymers can be extracted from leaf or stem of plants. Pterocarpus Indicus W. (PIW) and Jatropha Multifida L. (JIL) plants are good candidate as natural polymer sources. PIW and JIW polymers contain chemical compound so-called flavonoids which has C6-C3-C6 carbons conjugated configuration. The renewable type of polymer as well as their abundancy of flavonoid provide us to explore their physical properties. A number of research have been reported related to broad synthesis method and mechanical properties. So far there is no specific report of electrical conductivity associated to PIW and JIL natural polymers. In order to obtain electrical conductivity and its crystallinity of the extracted polymer films, it was induced on them a various fraction of silver nano particles. The film has been prepared by means of spin coating method on nickel substrate. It was revealed that FTIR spectra confirm the existing of rutine flavonoid. The crystallinity of the samples increase from 0.66%, to 4.11% associated to the respective various of silver fractions of 0.1 M to 0.5 M. SEM images show that there are some grains of silver in the film. The nature of electric conductivity increases a long with the addition of silver. The electrical conductivity increase significantly from 3.22 S/cm, to 542.85 S/cm. On the other hand, PIW films also shows similar trends that increase of Ag induce the increase its crystallinity as well as its electrical conductivity at semiconducting level. This result opens a prospective research and application of the green renewable polymer as optoelectronic materials. [ABSTRACT FROM AUTHOR]

The discovery of delafossite compound has encouraged more rapid technological developments particularly in transparent electronic devices. Copper oxide-based transparent thin films delafossite semiconductor recently give much attention in the field of optoelectronic technology, after the discovery of p-type CuAlO2. The potential applications of a p-type semiconductor transparent conductive oxides (TCO) have been applied in broad field of optoelectronics. To explore a broad physical properties interms of magnetic conducting subtitution is understudied. In this work we report the fabrication of delafossite film on Ni substrate and their characterization of CuAl1-xMxO2 delafossite compounds doped with Cr3+ and Fe3+ from the raw material of Cu(NO3)2.3H2O, Al(NO3)3.9H2O, Fe(NO3)3.9H2O and Cr (NO3)3.9H2O. The films were prepared using spin coating through a sol-gel technique at various concentrations of x = 0, 0.03, 0.04, and 0.05 for chromium and x = 0, 0.02, 0.04, 0.06, and 0.08 for iron doped. Crystal and microstructure were characterized by means of Cu-Ka Bragg-Brentano X-RD followed by High Score Plus and SEM-EDAX. The dielectric constants of the films were characterized using LCR meter. It was found that the CuAl1-xMxO2/Ni delafossite films were successfully fabricated. The CuAl1-xFexO2 compound crystallized with lattice parameters of a = b ranged from 2.8603 Å to 2.8675 Å and c ranged from 16.9576 to 17.0763 Å. The increase of the dopant give rise to the increase of the lattice parameters. Since iron has bigger ionic radius (69 pm) than original site of Al3+ with radius of 53 pm the crystal volume lattice also increase. Further analyses of increasing volume of the crystal, as expected, affected to the decreasing of its dielectric constant. The similar trends also shown by Cr3+ doped of CuAl1-xCrxO2 films with smaller effects. [ABSTRACT FROM AUTHOR]