Table of contents

3rd MRS-id Meeting is the continuation of successful biannual series including 1st MRS-id Meeting in Bali (2014) and 2nd MRS-id Meeting in Bandung (2016) organized by Materials Research Society of Indonesia (MRS-id). The conference was held on July 31st to 2 August 2nd, 2018 at Aston Denpasar Hotel & Convention Center, Bali, Indonesia. The theme of current meeting is "Materials for Energy and Environment Sustainability". The focus of the MRS-id meeting is to promote materials science and technology in Indonesia, regional area (such as ASEAN and Asia) as well as global. The MRS-id meeting is a platform for the gathering of researchers, lecturers and students who always seek for collaboration, exchanging ideas across all scientific disciplines.

The 3rd MRS-id Meeting was attended by 7 plenary speakers, 13 keynote speakers, 95 oral speakers and 45 poster presenters. These are the contribution from 11 countries across the world. The scope of meeting covers various aspects of advanced materials science and technology such as photonic materials, optical materials, biomaterials, biomedical materials, electronic materials, magnetic materials, porous materials and membrane. The submitted manuscripts from this meeting have been peer-reviewed and to the selected manuscripts, those has been published on Materials Research Express. Eventually, other 34 accepted manuscripts are for the publication on IOP Conference Series: Materials Science and Engineering.

The 3rd MRS-id Meeting organizing committee would like to acknowledge the enthusiasm of the participants, support from the sponsors, contribution from the international advisory boards and support from the heads of universities that lead to the success of this event.

Rino R. Mukti

Chair of 3rd MRS-id Meeting

Editors:

Khairurrijal Khairurrijal, Institut Teknologi Bandung, Indonesia (krijal@fi.itb.ac.id)

Rino R. Mukti, Institut Teknologi Bandung, Indonesia (rino@chem.itb.ac.id)

Hutomo Suryo Wasisto, Technische Universitaet Braunschweig (h.wasisto@tu-braunschweig.de)

Ariando, National University of Singapore, Singapore (ariando@nus.edu.sg)

Satria Z. Bisri, RIKEN Center for Emergent Matter Science, Japan (satria.bisri@riken.jp)

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The surface crack in flexure (SCF) is a method for the evaluation of the fracture toughness of advanced ceramics. Conventionally is practiced by using a Knoop indenter to make a very small pre-crack. Removal on indent and the plastically deformed zone is required before the fracture test. The purpose of this removal is to eliminate residual stresses under the Knoop impression and to obtain a semi elliptical pre-crack shape. In this work fracture toughness values by the SCF method are compared with those measured using the SEVNB (single edge V-notched beam) method. The material chosen for this purpose was gas pressured sintered silicon nitride (Si₃N₄) containing 3wt. % Al₂O₃ and 3 wt. % Y₂O₃ (SL200B, Ceram Tec, Plochingen, Germany). The varied parameters the amount of material removed from the surface. Short specimens with size 3 x 4 x >25 mm were prepared for this purpose. The fracture toughness of specimens with a surface removal in the range suggested from ASTM C 1421 were found to agree with the results obtained from SEVNB. A surface removal below the recommendation resulted in low values of fracture toughness. Increasing the amount of surface removal moderately was found to still fit with results obtained from SEVNB. Surface removal of much more from the recommended amount leads to failure from natural flaws.

Bolus is a material equivalent to tissue and used in radiotherapy process to increase a dose surface using electron beam. The bolus synthesis from a material equivalent to tissue is not easy, one of the alternative materials used is silicone rubber (SR). In this research bolus was synthesized with dimension of length x width x thickness is (17 x 17 x 1) cm³. Bolus has been characterized by CT-Scan to find relative electron density (RED) and linear accelerator (LINAC) to investigate percentage of surface dose (PSD) with two energy (8 MeV and 10 MeV). The RED value for bolus is 1.176, these results show the RED value for bolus between soft tissue and solid tissue. The PSD value at 8 MeV and 10 MeV are 102.32% and 101.32%, respectively. These results indicate that the silicone rubber material can be used as an alternative bolus material because it corresponds to the bolus function in radiotherapy.

Cerium oxide base materials have been attracting great attention as a promising electrolyte for intermediate temperature of solid oxide fuel cell (IT-SOFC) due to its excellent conductivity at a lower temperature. In this works, cerium from Indonesia local raw material was developed as a cheaper alternative precursor for preparing gadolinium doped cerium (Ce_0.9Gd_0.1O_1.95 or GDC10) electrolyte. The effects of polyethylene glycol 400 (PEG 400) as a surfactant on to physical properties of GDC10 electrolyte were studied. GDC10 powders were synthesized using co-precipitation method with the addition of various PEG 400 concentration i.e 0,1,2 and 3v/v%. Synthesized powders were characterized by using X-Ray Diffraction (XRD), Particle Size Analyzer (PSA), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infrared (FTIR) Spectroscopy. The XRD analysis indicates that crystallinity was enhanced and all of the peaks on samples correspond to the fluorite crystal structure of single phase CeO₂. The average crystallite size is about 11.37, 7.27, 6.75 and 7.02 nm for PEG 400 concentration of 0, 1, 2 and 3v/v%, respectively. SEM images show different morphology of particle regarding with the addition of surfactant. Particle size analysis exhibits decreasing of particle diameter as the addition of PEG surfactant. The smallest particle size was about 1.47 μm for 1v/v% of PEG concentration. The results of this works confirm that the addition of PEG 400 surfactant strongly affects particle size and morphology of GDC10 powders. However, addition PEG 400 as surfactant should be delivered in a certain amount to give optimum effects where according to this works it is about 1 -2v/v%.

We propose a new metamaterial antenna on electro-optic (EO) modulator for wireless terra-hertz detection through radio-over-fibre (ROF) technology. By wireless terra-hertz signal irradiation to the proposed device, strong terra-hertz electric field can be induced on the electric- LC metamaterial resonator. The induced terra-hertz electric field can be used for optical modulation through EO effects when a light-wave propagates into an optical waveguide located under the capacitive gap which the strongest induced terra-hertz electric field. Analysis of optical modulation is presented in details for operational frequency of 0.1 THz. The device fabrication process and the results of its measured characteristics are also reported.

Air pollution has become an environmental problem since it poses a serious effect on human health. In addition, circulation of air containing airborne particles including pathogens in an enclosed building like a hospital may lead to more severe health effects. Therefore, an air purifier is needed to prevent the spreading of those particles through air circulation. To address the issue, an antimicrobial membrane was prepared by embedding ZnO nanoparticles onto hollow fiber polypropylene (PP) membrane. Results showed that the prepared PP/ZnO membrane had a high air filtration performance as well as antibacterial properties. The membrane also showed a high filtration capacity or permeability with a relatively low-pressure drop. With those interesting features, the newly developed PP/ZnO membrane can be applied in air filtration, in particular for indoor spaces and other medical applications.

Anatase phase of Titanium dioxide (TiO₂) is a wide bandgap semiconductor which is active as photocatalyst material under ultraviolet light irradiation. Vanadium dopant has reported to enhance its photocatalytic properties toward visible light irradiation. However, vanadium doped TiO₂ has several limitations for further practical application such as its low surface area and difficult in recycling due to its superfine particle. Supporting this material into porous and large surface material like zeolite material supposed to improve its photocatalytic properties. In this research, vanadium doped TiO₂ (Ti_0.997V_0.003O₂) photocatalyst was supported on Indonesian natural Zeolite using sonochemical method to study the structural and optical properties of supported photocatalyst. Ti_0.997V_0.003O₂ was loaded into zeolite at various concentration ranging from 10 to 30 % w/w. The X-Ray Diffraction (XRD) data showed that Ti_0.997V_0.003O₂/Zeolite at various concentrations have characteristic of anatase, rutile and mordenite phase structure. Infrared spectra showed the typical vibrational mode of TiO₂ and mordenite phase. The sharp peak at 1370 cm-1 which is attributed to the lattice vibration of TiO₂ became weaker due to vanadium dopant. The Raman spectra showed that the anatase vibration mode position shifted to higher wavenumber caused by the interaction between Ti_0.997V_0.003O₂ and zeolite. Diffuse Reflectance Spectroscopy (DRS) data revealed that 15% of Ti_0.997V_0.003O₂ on Zeolite has the highest visible light absorption and the lowest band gap energy (2.77 eV or 447 nm) in comparison to the others composition.

The solid surface tension plays an important role in the heat and mass transfer system for heat exchanger equipment. In the nuclear power plant industry, Zircalloy 4 has been used for long time as structure materials. The purpose of the experimental is to study solid state surface tension behavior by measure contact angle of aquades and Nano fluid contain nano particle alumina on metal surface of Zircalloy 4 before and after oxidation at 700°C by sessile drop method. The experiment is to measure the static contact angle and drop of aquades and nano fluid contains nano particle alumina on zircalloy 4 with different spreading time from 1 to 30 minute. It was observed that zircalloy 4 after oxidation lose their hydrophobic properties with increasing elapsed time during drop of a aquades and nano fluid on the surface of alloy compared with zircalloy 4 before oxidation. As a result the contact angle of aquades and nano fluid on surface of zircalloy 4 before and after oxidation is decrease grdually during increasing elapsed time. While the magnitude diameter drops of aquades and nano fluid and wetting surface are increase with increasing elapsed time on the surface of Zircalloy 4 before and after oxidation. It was observed that oxidised zircalloy4 good wettability properties compare with non oxidised zircaloy 4.

On the attempt to increase transport properties of the photo-anode in DSSC, we synthesized rGO powder from graphite bar (commercially available) using modified Hummer's method. The SEM-EDS results had confirmed the attachment of the rGO layer to the FTO substrate. For DSSC cells, we made two cells configuration, the first one was stacking layers of rGO and TiO₂ resulting configuration of TiO₂/rGO/TiO₂ (A2) and rGO/TiO₂/rGO (A3), where rGO was deposited by spin coating and TiO₂ was deposited by a screen printing technique. The second one, the rGO powder was mixed with TiO₂ paste with several ratios in weight, namely TiO₂:rGO 40:1 (B1), 40:2 (B2), and 40:8 (B3) and then deposited on the FTO substrate by screen printing. The reference cell was assigned as A1 (TiO₂ only). From the conductivity measurement using the four-probe method, the utilization of rGO layer increased the conductivity of photoanode layer, namely (1.37, 2.9 and 6.3)x10⁻² Ω⁻¹cm⁻¹ for A1 to A3 and (1.5, 2.5, and 3.7)x10⁻² Ω⁻¹cm⁻¹ for B1 to B3. From the photovoltaic measurement, we found that the efficiency of the DSSC cell firstly increased with the insertion of rGO layer, from 1.8% (A1) to 4.59% (A2), and decreased to 3.22%, as the conductivity increased in A3. While for the composite of TiO₂:rGO, the efficiency of the cell reduced with the increased amount of rGO, from 3.45% (B1) to 2.9% and 1.9% for B2 and B3. We found that the reduction of photovoltaic performance was affected by two main factors, specifically, direct contact between rGO and redox species in the electrolyte, which induced recombination process, and conductivity of the photo-anode layer. To fully achieve the advantage of rGO utilization in photo-anode, once must be considered was the use of protection layer on top of the rGO layer to avoid direct contact between the rGO/electrolyte interface.

Quenching is performed as part of steel heat-treatment to enhance mechanical properties, by rapid cooling. Factors that affect the selection of quench medium are hardenability of material, geometry, and dimensions of the component. In recent developments, nanofluids are used to improve heat transfer capacity. In this research, nanofluids were synthesized using the two-step method. Milling of particles was done using a high energy ball mill for 15 hours at 500 rpm. Observation of particle size, material composition, and morphology of particle, and surface changes of the particle were measured by Field-Emission Scanning Electron Microscope (FE- SEM), and Energy Dispersive X-Ray Spectroscopy (EDX). Water-based nanofluids with a volume of 100ml were produced using the two-step method, with carbon concentrations of 0.1%, and 0.5% and Sodium Dodecylbenzene Sulfonate concentrations of 0%, 1%, 3%, and 5%. Samples of S45C steels were austenized at 1000°C for 60 minutes. Hardness testing results correspond to the severity of the quenching mediums, with peak hardness of 845 HV for 0.1% Carbon with 1% SDBS, and 878 HV for 0.5% carbon with 3% SDBS. Hardness testing results show a significant improvement over results without SDBS addition. Excess surfactant addition yields a lower hardness due to the re-agglomeration of particles.

We reported preliminary study about dried nata de coco for extend the shelf life of fruits We made nata de coco by mixing coconut water and adding Acetobacter xylinum. Nata de coco was dried and compacted with hot press. The design of nata de coco as an absorbent of water made similar to the design of silica gel. Moisture absorption test was carried out by storing dried nata de coco samples along with fruits (apple, mango, pear) in one container. Fourier Transform InfraRed Spectrometer (FTIR Alpha Platinum ATR A220) was used to check the water content in the dried nata de coco sample. The result showed that dried nata de coco succesfully to absorb water vapor.

Gadolinium-doped cerium (Ce_0.9Gd_0.1O_1.95, GDC) as an electrolyte in IT-SOFC has higher performance in nano-sized than the other sized. Carbonate was known as a precipitant agent that could affect the morphology and size of the particle. In this study, the effects of various carbonates as a precipitant agent on the synthesis of GDC by co-precipitation method were investigated. Cerium in the form of Ce(NO₃)₃.6H₂O (cerium nitrate hexahydrate) used in the synthesis process. Three types of carbonates, i.e. ammonium carbonate, potassium carbonate, and sodium hydrogen carbonate, namely GDC1, GDC2, and GDC3, respectively, was used as a precipitating agent. The GDC powder resulted was then characterized by X-Ray Diffraction (XRD), Fourier Transform Infra Red (FTIR), Particle Size Analysis (PSA), and Scanning Electron Microscopy (SEM). The carbonates variation affected the physical properties and the formed particle of GDC. GDC2 showed the optimum carbonate that produces electrolyte GDC with better properties as an IT-SOFC electrolyte based on physical properties.

In this paper, the effect of particle size distribution on the preparation of bonded NdFeB isotropic permanent magnets was investigated. Different particle size distribution of NdFeB powders was prepared by sieving method using standard test sieves of #100, #200, and #325 meshes. Varied distribution of particle size was mixed with 3 wt% of epoxy binder and compacted by uniaxial hydraulic pressing machine to produce bonded isotropic green body. Bonded NdFeB green body was cured by vacuum drying machine under temperature 100 °C for 4 hours with vacuum pressure of 10 mbar. The characterization performed were bulk density measurement, particle size analysis, microhardness Vickers, SEM image and hysteresis curve. We find that the hardness of bonded NdFeB magnets decreased as the particle size decreases. Contrary to common belief that the finer powder with sharply particle size distribution not always give the highest product characteristics. The optimum characteristics of bonded NdFeB was obtained by the mixture of #100+#200 meshes powders with bulk density, hardness, magnetic remanence, coercivity, and energy product of 5.87 g/cm3, 88 HV, 6.5 kG, 11.15 kOe, and 9.4 MGOe, respectively. Therefore, the middle range of particle size distribution is effective to obtain high quality bonded NdFeB permanent magnets.

Magnetite (Fe₃O₄) nanoparticles becomes a new innovation that gets attention of biomedicine scientists. Magnetite can be applied to cancer treatment as a drug carrier because it's good biocompatibility and very low toxicity. The purpose of this study was to determine the effect of temperature and stirring rate on the magnetite particle characteristics prepared by co-precipitation method. Firstly, FeCl₃ and FeCl₂ with 2:1 mole ratio were reacted with 10% NH₄OH at 40 - 80°C temperatures and stirring speed of 300 - 500 rpm in a beaker glass. Subsequently, the precipitate was separated using filter paper and it dried into air oven at 100°C. The properties of obtained magnetite powder were determined using XRD and SEM. From XRD pattern indicates that magnetite formed at all temperatures with crystallite diameter in the range of 10-12 nm. The SEM results indicate the agglomeration of the magnetite particles with size in the range of 2.7 to 3.3 μm. In the other hand, the higher of temperature and stirring rate of agitation will make the agglomeration of the particles become more uniform. The increasing of temperature and the stirring rate will increase the magnetite crystallinity level.

Magnesium composite with Mg-Al-Sr matrix reinforced by nano-SiC has successfully fabricated by stir casting process. Addition of nano-SiC into magnesium matrix varies by 0.05; 0.10; 0.15; 0.20; and 0.25 in percent of volume fraction (Vf-%). The optimum mechanical properties are found in composition of 0.15 Vf-% nano-SiC. The number of hardness, impact toughness, and wear rate of this composition are 68.4 BHN, 0.065 Joule/mm², 1.03310⁻⁵mm³/mm respectively. Addition of 0.15 Vf-% nano-SiC enhances the hardness by 26%, impact toughness by 23.57%, and wear resistance by 38.40% respectively. Furthermore, the existence of nano-SiC in Mg-Al-Sr matrix modify the microstructure of composite by dispersing the intermetallic compounds. However, it is observed that higher nano-SiC content tends to agglomerate thus the strengthen mechanism cannot effectively occur. Microstructure analysis using OM and SEM reveals that the addition of nano-SiC transforms the dendritic matrix to globular equiaxed. EDX result predicts the phases formed are α-Mg, Al₄Sr, Mg₁₇Al₁₂, MgAlSr, and XRD analysis finds the existence of SiC, SiO₂.

Platinum film growth using thermal evaporation method was studied using molecular dynamics simulation. This platinum film was intended as catalyst film for graphene growth. Tersoff, Eam and Lennard-Jones potential were used to describe interaction of Si-Si, Pt-Pt and Pt-Si respectively. Deposition process was performed with low incident energy to represent thermal evaporation method. Our simulation found that heating temperature at 400 K produced platinum film with higher percentage of crystal structure than other heating condition 300K, 500K & 600K. We also found transition phase from fcc to bcc at 600K.

The mechanical properties of a material depend on the quenching process. In this process, there is a rapid cooling from elevated to room temperature in a short time by using a quench medium. Therefore, the phase transformation from austenite to martensite occurs. The common medium used in the quenching process is water, oil, polymer, and gas. Nanofluids are started to be used as a quench medium because they offer better thermal conductivity compared with the conventional medium. Selection of carbon-based nanofluids as a quenching process medium aims to obtain high thermal conductivity values and controllable cooling rates. Thereby, the expected microstructure of the material could be relatively easier to form. In this paper, carbon particles were obtained using a top-down method with a planetary ball mill for 15 hours at 500 rpm. Based on the electron microscope and spectroscopy results, the particle dimension was average at 15 μm after milling, and the carbon purity of the powder used in this research was 99%. Carbon particles at 0.1%, 0.3%, and 0.5% with variation of non-ionic surfactant Polyethylene Glycol of 1%, 2%, 3%, 4% and 5% respectively was used in this research. AISI 1045 or JIS S45C carbon steel was used as a steel sample, and austenized at 1000°C for 1 hour and then quenched in the microfluid. The hardness obtained was up to 811 HV for the sample quenched in 0.5% carbon and 1% Polyethylene Glycol. The improvement was more than 100 HV, compared with the sample quenched in distilled water, which had a hardness only 666 HV.

Heat treatment of material particularly quenching requires a high thermal conductivity quench medium. Hardenability of material, dimension, and geometry of the component are considerate on choosing quench medium. The cooling rate of quenching affects the properties and microstructures by creating specific phase transformation to occur. Enhancing the quench medium by accelerating the cooling rate can be attained by the addition of nanoparticle which has higher thermal conductivity. This nanoparticle-added medium is commonly termed as nanofluid. Commercial and laboratory grade of TiO₂ was used as the nanoparticle to distilled water as the nanofluid base to acquired higher conductivity on the heat treatment process. In this experiment, a top-down method was done to obtain TiO₂ particles by grounding using a planetary ball mill for 15 hours at 500 rpm. Nanofluid quench medium was mixed with TiO₂ in various concentration of 1%, 5% and 10% with a volume of 100 ml each. Samples of AISI 1045 or JIS S45C carbon steel were used to obtain different cooling rate on a different type of TiO₂ particles. Samples were heat treated by austenizing at 1000°C for 1 hour, followed by rapid quenching in nanofluid quench medium with the addition of agitation as quenching variable. Observation of particle morphology and size, material composition, and the change of surface ere measured by Field-Emission Scanning Electron Microscope (FE-SEM), and Energy Dispersive X-Ray Spectroscopy (EDX). Initial characterization showed that the TiO₂ particle size was at 150 nm range, and roughly free from any impurities. Martensite microstructures have the most significant area and the amount at laboratory-grade TiO₂ in 0.2 wt% composition, followed by commercial-grade at 0.3 wt% composition.

The combination of of wireless millimeter-wave (MMW) bands and fiber optic cables is able to compensate the propagation loss of millimeter waves in broadband communications and high-resolution imaging. This paper discusses the design and the realization of optical modulator using coplanar stripline (CPS) structure completed with the u-slot antenna patch for RF signal input. The substrate used for CPS structure is Lithium Niobat (LiNbO3) due to its large electro optical coefficient. A 10 Ghz radio wave frequency is inputted via microstrip u-slot antenna patch array 2 x 1 with input impedance 50 Ω, and acceptable return loss -10 dB. The light waves for the carrier are generated from the laser diode. Several measurements have been completely done and reported. The design is carried out by means of varying physical variable value which results in specification of the operating frequency 10 GHz. This is a pure research since the obtained results are not directly applied to the radio-over-fiber (RoF) technology.

Azo dyes are the major type of textile dye in the world, owing to their stability to light, microbial degradation, and physical degradation due to washing. However, these properties also lead to problematic removal or degradation of azo dyes that pollute the water body. In this research, nanofiltration (NF) thin film composite (TFC) membranes based on polyetherimide (PEI) polymer are utilized to remove an azo-based dye from a simulated textile wastewater, namely Reactive Black 5 (RB5). PEI is firstly dissolved by using N-methyl-2 pyrollidone (NMP) as solvent, combined with acetone as a non-solvent, and converted to be membranes via phase inversion method. The created membrane will be further modified by interfacial polymerization (IP) method using trimesoyl chloride (TMC) and m-phenylene diamine (MPD) as precursors of acyl chloride and amine, immersed in two immiscible liquids of hexane and water, respectively. This method fabricates a new selective layer composed of tightly-packed nylon-like polyamide layer that might improve the separation performance. Membranes from polymeric dope solution of PEI/acetone/NMP 15/65/20 (w/w) were employed due to acceptable flux and rejection, compared to other formulations. They were then modified by using IP method (0.05% TMC in hexane and 1.5% MPD in water) to create PEI-TFC membranes. The PEI-TFC membranes exhibited fluxes around 0.01 L m⁻² h⁻¹ psi⁻¹, with rejection of RB5 dyes up to 90%, which suggested the successful IP method on the PEI membranes. SEM and FTIR were carried out for comprehending the reasons behind the improved separation performance, and they revealed that the TFC nylon-like selective layer was successfully developed, from both physical and chemical perspectives, respectively. The fabrication of NF TFC membranes might open some new roads for environmental application of membranes in Indonesia.

Polypropylene (PP) is one of the most widely used polymer materials, such as in textile, automotive spare part, furniture, household appliances, and packaging. However, PP is very difficult to degrade naturally. When the product from PP is not reused and discharged into the environment, this plastic can cause problems to the environment. One of the solution to improve degradability of PP is by adding pro-oxidant additives. The addition of pro-oxidant additives can make polypropylene to easily oxidize and degrade into shorter chains by producing carbonyl groups. The pro-oxidant additive used in this research is manganese palmitate. The additive was synthesized by reacting palmitic acid with sodium hydroxide and followed by reaction with manganese chloride tetrahydrate. The purpose of this research was to study the effect of manganese palmitate as a pro-oxidant additive to the structure and mechanical properties of PP before and after thermal treatment. The thermal treatment was carried out by providing heating in PP at various temperatures (25, 60, and 90°C) for 2, 4, 6, 8, and 10 days. The structure and mechanical properties of PP was characterized by functional group analysis (FTIR) and mechanical properties (Tensile tester). FTIR spectra of PP film after thermal treatment at temperature 60 and 90°C showed the presence of carbonyl group in 1700-1720 cm⁻¹ region. After thermal treatment at 90°C, PP film could not be analyzed by mechanical properties because it was damaged and destroyed. The peak intensity of the carbonyl group increased with the increasing temperature of heating. PP films with the addition of manganese palmitate both before and after thermal treatment have a lower tensile strength and elongation compared to the pure PP, but their modulus young are higher, so that the films of PP with addition of pro-oxidant became more fragile and rigid. In addition, the PP film with heating treatment at 90°C cannot be analysed due to it was damaged and destroyed.

Tendon injury causes significant morbidity during the productive age, and the number is increase in recent decades. Tensile strength is the most important factor in tendon function of style, and the results of repair should be able to withstand large current style of early mobilization. This research was an experimental research design with the post-test only control group design with the subject of the rabbit. A total of 18 research subjects who meet the requirements of the study inclusion were randomly divided into treatment and control groups. Control group was a group of rabbits that were repaired with 4 strand modified Kessler technique after Achilles tendon cut sharply. While the treatment group were a group of rabbits that were repaired with continuous-cores technique. The ratio of collagen I/III in rabbit Achilles tendon repair with the technique of continuous-cores are smaller compared to the control group with value of P <0.05. Also Showed statistical analysis tensile strength of rabbit Achilles tendon repair with the technique of continuous-core is greater than the control group at P <0.05.

The precise and accurate measurements of material properties are needed in biomaterial and tissue engineering study to better describe the properties of material and ensure the product quality Diffusion Magnetic Resonance Imaging (MRI) is used in biomaterial study as a biomarker for composition and structure of biomaterial and a tool to observe mechanical properties of materials. The previous study predicted the mechanical properties of polyvinyl alcohol (PVA)-based material for biomedical phantom using diffusion MRI. The measurement was performed based on water diffusion inside gel and the method only worked for a certain concentration of PVA. In this study, Diffusion MRI was used to observe water diffusion of agarose as a potential hydrogel material for phantom development and tissue-mimicking materials.

Lactic acid has been widely used as flavour and preservative in the food, pharmaceutical, leather and textile industries. It can be produced by fermentation process of the substrates with high lactose content, such as cheese whey, soybean milk, corn, and potatoes. Among various existing technologies, membrane bioreactor is one of the promising methods to achieve high productivity of lactic acid. In addition, membrane bioreactor allows integration of fermentation and separation steps, thus it able to simultaneously maintain high cell density, recycle the cells for further use, and continuously remove lactic acid from the fermenter.

The hydrogénation of CO to produce synthetic natural gas (SNG) is highly exothermic and usually catalyzed by nickel as an active site. These reactions are typically conducted under elevated pressures and low temperatures to shift the reversible reactions to the products. However, conducting reaction under such low temperature is kinetically limited. An alternative method that can be applied to ameliorate this limitation is by conducting a dynamic operation. This study focused on model development and reactor approach for dynamic fixed-bed operation intended for CO methanation. One dimensional pseudo-homogeneous reactor model was developed for a typical laboratory scale by neglecting internal and external diffusion based on Weisz-Prater, Anderson, and Mears criteria. The gas phase model was governed for compounds in the bulk phase. The model consisted of the dynamic term, convective term, diffusive term, and source term. The design criteria involving pressure drop, ratio of the height of catalyst bed to particle diameter (L_B/d_p), ratio of reactor diameter to particle diameter (d_r/d_p), ratio of bed length to reactor diameter (L_B/d_r) and axial dispersion were taken into consideration. A kinetic model to complement the simulation was taken from literature. The reactor model was simulated for steady-state and unsteady-state operation with optimum feed composition. The result of steady-state model simulation was considered as a base case and comparison to judge the reactor performance under unsteady-state operation. Modulating the value of the inlet CO fraction in step function was introduced to the unsteady-state model in order to enhance methane production. The simulation results showed that the highest methane production could be achieved by modulating CO inlet fraction between 0.45 and 0.4 with the overall switching time of 25 s.

Electrolytes system plays an important part in Lithium Ion Batteries (LIBs) due to its role in lithium ion (Li⁺) transport between anode and cathode. Commercial LIBs use organic carbonates-based electrolytes system, but these electrolytes are flammable and volatile. For these reasons, replacement with non-flammable, non-volatile and high conductive compounds become recent research focus. Owing to the excellent properties, ILs are expected to cover the limitation of the organic-based electrolytes system in LIBs. The conductivity of electrolytes system which consists of dimethyl carbonate (DMC)/diethyl carbonate (DEC) (1:1, v/v) as organic solvent (OS) and imidazolium-based ILs is measured at various temperatures. Furthermore, the thermal stability of the electrolytes and the redox properties of lithium ion in IL-based electrolytes system are also investigated. [bmim][BF₄]-based electrolyte yields a conductivity of ~13 mS cm⁻¹ at 20 °C which is 10,000 times higher than DMC/DEC based only. Thermal analysis shows that the IL-based electrolytes decompose at 360 °C, much higher than the organic-based only (∼110 °C). Cyclic voltammetry measurement of the ILs-based electrolytes with [bmim][BF₄] : DEC: DMC (3:1:1) + LiBF₄ 0.2 M compositions displays reversible redox reaction. The presence of [bmim][BF₄] affects the redox reaction of Li+ ion, in both current and potential. Based on these results, a mixture of ILs and organic solvent has a potential as a new electrolytes system in the next LIBs.

Multilayer printed circuit board (PCB) consists of many layers in PCB. In order to connect one layer to other layers is needed plated-through-hole (PTH). PTH is commonly formed from the copper metal using some methods such as electroplating or electroless plating. Electroplating is method which there is adhering process the copper metal using the electrical current. This method is easy and cheap in PCB manufacture. One of the important part of electroplating result is surface morphology and thickness of PTH in multilayer PCB. The objective of this study is to im the electroplating current in electroplating process to learn more about the effect of electroplating current against the surface morphology and thickness of PTH.. The electroplating current applied in this experiment is at 5 A, 10 A, 15 A, and 20 A. In this research is also used Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) to characterize the formed PTH in multilayer PCB. The results shows that the PTH was successfully formed in through hole of multilayer PCB. The thickest PTH is about 37.8 μm for the applied current 20A and the smoothest morphology of PTH cross section is at the electroplating current 15 A.

In a system of a thin ferromagnetic layer sandwiched by non-magnetic metals, the precession of magnetization of the ferromagnetic layer has been shown to generate spin current in the adjacent non-magnetic metals. The spin current arises from the spin-dependent scattering that is originated by the exchange interaction between the magnetic moment and the spin of adjacent normal metal's electron. While the theory was originally studied in magnetic multilayer that consists of a thin ferromagnet sandwiched by non-magnetic materials, to be able to describe a more realistic ferromagnetic layer, we need to study how magnetic moments far from the interface can influence the spin current generation. We use a simple model one dimension ferromagnetic spin chain to show the criteria in which the collective movements of the spin moments can enhance the spin current generation.

The additive effect of ZrO₂ nanoparticles in Fe-18Al based alloys through the mechanical alloying process to the porosity and hardness was investigated. Results of microstructure observations showed that the only intermetallic Fe₃Al present as the major phase in the samples along with other phases which are very minor together with the presence of porosity that indicated by objects of dark color. The porosity tends to diminish with the addition of ZrO₂ nanoparticles. However, the porosity is still visible on the Fe-Al alloy with the addition of 2% additive and the higher compaction load especially in the surface area. The results of phase study by XRD confirmed the presence of the intermetallic Fe₃Al. It is shown that ZrO₂ nanoparticles are dispersed in the metal matrix. The presence of ZrO₂ also confirmed by SEMEDS. The fraction of pores that estimated based on the microstructure observation showed a decrease with an increase in volume fraction of ZrO₂ nanoparticles and the compaction load. The study concluded that the hardness of Fe-18Al alloys increased with a decrease in porosity which achieved in Fe-18Al alloy added with 2% ZrO₂ nanoparticles. The lowest porosity level is 0.17% and the highest hardness value is 352.59 HV

In this study, we report about the characteristics of ion transport of chitosan composite membranes "chitosan-silver nanoparticle". The chitosan composite membranes were prepared by a casting method using chitosan as a matrix, silver nanoparticle (AgNP) as filler, and acetic acid 1% as a solvent. The various amount of filler added e.g. 10, 100, 250, 500, 750, and 1000 μg. These membranes called chitosan composite membrane Ch-AgNP10, Ch-AgNP100, Ch-AgNP250, Ch-AgNP500, Ch-AgNP750, and Ch-AgNP1000. A membrane without AgNP has also been prepared named chitosan membrane (Ch membrane) as a comparison. The ion transport experiments conducted by using a cell model consisting of two chambers, chamber 1 and 2, and the area of the membrane was 9.616 cm². The driving force used is a gradient concentration (dC/dx). The electrolyte solutions used were KCl and CaCl₂ with concentrations of 0.1, 1, 10, 100, 250, 500, 750, and 1000 mM. The voltage difference (V) is measured using Ag/AgCl electrodes which connected to a voltmeter. All measurements were done at room temperature, 28.1°C. The result showed that the obtained J_diff -V curves of chitosan composite membranes are similar to J_diff -V curves of Ch membrane, where the diffusion current densities of chitosan composite membranes increased with increasing the concentration gradient of solution. It also depends on the electrolyte solutions. The diffusion current density of chitosan composite membranes had affected by the amount of AgNP added that is increased as increasing the mass of AgNP added.

The research and development of biomass-based activated carbon (AC) has attracted much attention from researchers due to the abundant resource of biomass, including corncob waste. The urgency to find alternative and innovative applications for simple, inexpensive carbon material can be obtained by synthesizing the corncob waste which is abundant renewable resource and suitable for carbon properties. The use of chemical agent during activation process is of important to produce the desired AC, including high surface area and excellent electrical conductivity. Among the various chemical agents, KOH and ZnCl₂ have been widely applied for synthesizing AC. This study aims to find out the characteristics of corncob-originated activated carbon (CAC) using these two chemical agents. Step by step of activating carbon from corncob will be determined briefly. Corncob was dried and chopped. Then it was carbonized. After that, the carbon result was soaked in each chemical agent solution, KOH and ZnCl₂, in different molarity for carbon chemical activation. For physical activation, impregnated carbon was carbonized again in high temperature under inert gas atmosphere until AC was obtained. We employed scanning electron microscopy (SEM), X-Ray diffraction (XRD), and Raman Spectroscopy measurement to characterize the CAC samples. The results showed that the application of KOH and ZnCl₂ at a different optimized process parameters exhibited the different results of surface morphology, structures, and crystallyte size. The crystallite size of the activated carbon using different chemical activating agents with varied concentrations is diverse enough. The XRD data revealed the average crystallite size of carbon with KOH as the activator is ∼45 nm in three different conditions. However, in the case of ZnCl₂ as the activating agent, it shows the average size of ∼65 nm. This number is significantly higher than the activated carbon impregnated with KOH . Visual observation of SEM images gives an impression on the carbon pore where CACK12 posess the highest pores among those analytes. The synthesized corncob activated carbon can be used in many functional application such as energy storage materials, agriculture, and adsorbents in industrial and environmental sectors.

Silver nanowires (Ag NWs) have attracted more attention in the last decade due to their potential applications in the next generation of flexible and wearable electronic devices. Several simple approaches were used to produce highly crystalline Ag NWs, but the synthesis parameter should still be precisely optimized to obtain high aspect ratio Ag NWs. In this study, we observed the morphological changes of Ag NWs during the synthesis to obtain the precise temperature and reaction time. AgNO₃ is used as a source of metal ions, polyvinylpyrrolidone (PVP) as a capping agent or stabilizing agent, NaCl as a control agent, and ethylene glycol (EG) as a reducing agent and solvent. Synthesis was performed with temperatures of 150°C and 170°C, and it was observed in reaction times of 10, 15, 40, 80, and 120 min. The results show that Ag nanoparticles were formed in the first 10 min of the reaction then continue to form Ag NWs up to 80 min. After that, the diameter of Ag NWs starts to expand from 7.1 nm to 8.8 nm. The highly crystalline Ag NWs with an aspect ratio of 191.7 ± 9.8 were obtained in the synthesis performed at temperature of 170°C in 120 min.

In this study, Fluorine-doped Tin Oxide (FTO) was fabricated and synthesized by using spray pyrolysis methods for solar cells applications through the variation of the concentration and deposition time of precursor solution of SnCh:F. The glass substrate furthermore was heated at a temperature of 450°C prior to deposition and the sheet resistance was about 56 to 137.25 Ω/cm². X-Ray Diffraction, Scanning Electron Microscopy, UV-Vis Spectroscopy, and four-point probe were employed to investigate the characteristic of the FTO. This product was further applied as an electrode in the dye-sensitized solar cell (DSSC) and a photovoltaic effect was observed.

In order to fabricate a low-cost dye-sensitized solar cell (DSSC), carbon has become a highly preferred catalytic material as counter-electrode, particularly for DSSC with monolithic structure. This paper presents novel synthesis method of carbon-based composite pastes using two types of carbon material, i.e. carbon nanopowder and activated carbon. The concentrations of the inorganic binder added to the composite pastes were varied to investigate their effect on the physical properties of the counter electrode and the electronic properties of the constructed monolithic DSSC. The inorganic binder used in this work was titanium dioxide nanoparticles, Evonik P25. After optimization, power conversion efficiency of 0.221% was achieved by the monolithic DSSC with counter electrode composite comprising activated carbon and titanium dioxide with weight concentration of 0.5 g and 0.25 g, respectively. Characterizations using gas sorption technique showed that the shape of the hysteresis curves obtained for all composites resembled the isotherm curve Type II and H3, indicating the presence of micropores. Furthermore, higher concentration of titanium dioxide nanoparticles as binder led to counter electrode with lower surface area. The solar cell efficiency, however, was found to be not only correlated to the surface area or the binder composition, but it was also determined by the type of the carbon material.

Thermal conversion of biomass to produce energy inevitably generates ash as residual matter. Therefore, sustainable utilization of biomass should also consider reuse measures for the ash. This research examines the conversion of locally available biomass ashes in Indonesia into geopolymer. This is an environmentally more benign alkali-aluminosilicate alternative to the ordinary Portland cement produced by low-temperature reactions between aluminosilicates and concentrated alkali solution. Biomass ash sources in this study are corn stover, coconut shell, and sugarcane bagasse. Biomass ash blends are prepared according to a ternary simplex centroid mixture experiment design. These blends are reacted with activator solutions containing NaOH and Na-silicate and blended with sand aggregate to produce geopolymer mortar specimens. Early compressive strengths of geopolymer mortars range from 7.2 to 10.4 MPa, which surpasses the SNI 15-2049-2004 national standard for Portland cement with low heat of hydration. Statistical analysis of the experimental data indicates that the early strength as a function of biomass ash blend formulation is represented by a quadratic mixture model. Bagasse ash produces the highest strength. The quadratic terms consist of bagasse-corn and bagasse-coconut antagonistic blending terms. Morphology of the geopolymer mortar fracture surface indicates good bonding with the sand aggregate. Extensive acicular crystal growth within the amorphous geopolymer gel phase is observed in lower-strength formulations, which points to the formation of zeolite-like phase in the geopolymerization process. While the correlation of biomass ash type to the structure of the resulting geopolymer is yet to be established, this work has clearly identified the technical feasibility of producing geopolymer with satisfactory strength from tropical biomass ashes.