bluuebunny/crossref_metadata_2025_split huggingface dataset:
Porous geopolymers: processing routes and properties
Authors: Kovárík Tomáš , Hájek Jirí 
Published: November 2019

Abstract
Cellular ceramics constitute a specific class of materials containing a high level of porosity, greater than 60 vol%, which are characterized by the presence of three-dimensionally arranged open and/or closed cells. Because of their structure, cellular ceramics exhibit a unique combination of properties such as low density, low thermal conductivity, low thermal mass, high permeability, high thermal shock resistance and high specific surface area, making them essential for various engineering application. Nowadays, porous geopolymers have been the focus of promising research in the field of porous inorganic materials because of their unique combination of good thermal stability and excellent mechanical properties. An interesting technological feature is that their solidification kinetics is easily adjustable and thanks to ceramic-like structure they have significant structural stability at elevated temperatures. The processing methods used for the fabrication of porous geopolymers can be divided into various approaches. Many methods have been explored to synthesize reproducible porous sponges or foams from geopolymer systems, such as gaseous method, rapid solidification, foaming, freeze-casting and/or combination of them. Concerning the macro/micro-structure of cells, the processing can be strongly influenced by various characteristics as a chemical composition, rheological behaviour of the slurries, kinetics of pore formation and hardening behaviour. This study presents methods of processing and manufacturing approaches with respect to types of porous materials and experimental results in this field.
Detection technique of the optical and thermoradiative characteristics with compensation effect of reflection and transmittance indicatrices for the semitransparent materials with high subsurface scattering
Authors: Merzlikin Vladimir G. , Bystrov Andrey V. , Smirnov Sergey V. 
Published: November 2019

Abstract
The experimental set-up is developed for detection of reflection and transparence coefficients of semitransparent materials within visible and IR radiation diapasons. The peculiarity of the set-up is using the spectral photometric integrating spheres for effect compensation of reflection indicatrices of tested materials with fixed wavelengths 0.63 µm 1.15 µm (near IR), 2.79 µm and 3.39 µm (middle infrared) of probing laser radiation. In the first case the integrating sphere is a photometric ball which made from porous fluoroplastic with high reflectivity up to 97-99%. For the second range an aluminum sphere (sand blasting) was used. The application of the photometric sphere reduced the measurement error, connected with different sensitivity of photosensors to beam slope angle of detected radiation reflected (transmitted) for flat material samples with different indicatrices of reflection (transmission). The proposed method of experimental measurements of spectral photometric characteristics of reflection and transparent improve the accuracy of theoretical estimations of the optical (thermoradiation) parameters (absorption and scattering indexes), as well as the functions of a thermal radiation heat source for the calculation of temperature fields in semitransparent materials. For the first time, a computational and experimental estimation of scattering and absorption indexes (with an accuracy not less than 1%) were carried out for semitransparent materials with high scattering (porous ceramics based on stabilized zirconium dioxide) in the middle infrared range of wavelengths which is most problematic for optical measurements.
The Properties of Bolus Material using Silicone Rubber
Authors: Sutanto Heri , Marhaendrajaya Indras , Jaya Gede Wiratma , Hidayanto Eko , Supratman Astri Suppa , Astuti Santi Yuli , Budiono Tris , Firmansyah Muhammad Agus 
Published: November 2019

Abstract
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.
Metamaterial Antenna on Electro-Optic Modulator for Wireless Terra-Hertz Detection Through Radio-Over-Fibre Technology
Authors: Wijayanto Yusuf Nur , Fathnan Ashif Aminulloh , Kanno Atsushi , Mahmudin Dadin , Daud Pamungkas 
Published: November 2019

Abstract
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.
Effect of Sodium Dodecylbenzene Sulfonate as Anionic Surfactant on Water based Carbon Nanofluid Performance as Quench Medium in Heat Treatment
Authors: Oktavio L , Ramadhani C A , Rakhman D , Harjanto S , Putra W N 
Published: November 2019

Abstract
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.
Effect of Particle Size Distribution on the Preparation of Bonded NdFeB Permanent Magnet
Authors: Kurniawan C. , Wahyuni S. , Ramlan  , Setiadi E. A. , Sebayang P. 
Published: November 2019

Abstract
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.
Synthesis of Magnetite Nanoparticles via Co-precipitation Method
Authors: Fadli Ahmad , Komalasari  , Adnan Arisman , Iwantono  , Rahimah  , Addabsi Adela Shofia 
Published: November 2019

Abstract
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.
The Role of Nano-SiC on Characteristics of Mg-Al-Sr/Nano-SiC Composites Produced by Stir Casting Route
Authors: Sartika Vioni Dwi , Syahrial Anne Zulfia 
Published: November 2019

Abstract
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.
Polyetherimide nanofiltration membranes modified by interfacial polymerization for treatment of textile dyes wastewater
Authors: Febrianto Gabriel , Karisma Doni , Mangindaan Dave 
Published: November 2019

Abstract
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.
On The Application of Diffusion Magnetic Resonance Imaging for Study of Agarose
Authors: Dwihapsari Yanurita , Zakiah Salma Niatu , Darminto  
Published: November 2019

Abstract
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.
Simulation of Feed Modulation on Dynamic Fixed-Bed Reactor for CO Methanation over Ni-based Catalyst
Authors: Nuravifah Utari , Putri Sarah Eka , Wibisono Yogi , Budhi  , Rizkiana Jenny 
Published: November 2019

AbstractThe 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 (LB/dp), ratio of reactor diameter to particle diameter (dr/dp), ratio of bed length to reactor diameter (LB/dr) 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.
Spin Current Generation in One – Dimension Spin – Chain Model of Insulating Magnetic Interface
Authors: Cahaya Adam B. , Majidi M. A. 
Published: November 2019

Abstract
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 Ion Transport Characteristics of Chitosan Composite Membranes ‘Ch-AgNP’ with Emphasis on the Amount of Filler
Authors: Rupiasih Ni Nyoman , Suharta W. G. , Sumadiyasa Made , Ketut Putra I , Mega Trisnayani Putri Ni Made Ayu 
Published: November 2019

Abstract
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 Jdiff -V curves of chitosan composite membranes are similar to Jdiff -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.
Influence of Inorganic Binder Composition on the Structure-Property Relationship of Monolithic Dye-sensitized Solar Cells with Carbon-based Counter Electrode
Authors: Nursam N M , Shobih  , Rosa E S , Hidayat J , Mubarak Z 
Published: November 2019

Abstract
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.
Synthesis of Geopolymer from Blends of Tropical Biomass Ashes
Authors: Samadhi Tjokorde Walmiki , Wulandari Winny , Suroto Afiana , Agung Dendi Satriya 
Published: November 2019

Abstract
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.