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This research focuses on the properties and capabilities of carbon nanotubes (CNTs) as reinforcing agents in ceramic composite bearing components. The addition of CNT to pure ceramics can form composites with much better performance than conventional ceramics for various applications. The study was started from the pure ceramics in their use as a component of bearing total hip arthroplasty and the damage that occurred after implantation. The study covers factors that cause degradation of conventional ceramics introduction of properties and use of CNTs as new reinforcing agents for ceramic composite materials widely used sintering method and the heat and pressure parameters used during the sintering process to meet the standards for the manufacture of Total Hip Arthroplasty (THA) bearing component. The contact and buckling behaviors of the CNTs influence the composites friction properties. The presence of CNT until 20 wt% of CNT exhibited improve wear resistance with lower friction with the increase of weight percent. CNT reinforced ceramic coating might be capable to withstand high load-bearing conditions. Plastic deformation can be one of the critical processes in wear in the ceramics wear mechanism. Other processes are cracking and chemical reaction. The microstructures and porosity take an important role in indicating the ceramics wear properties and wear mechanisms.

Observation on the effects of rare earth impurities on the properties of Ce0.9Gd0.1O0.195 (GDC) composite electrolyte has been performed. Indonesia has abundant rare earth elements especially CeO2, which one of the resources is from monazite mineral. In this study, the GDC powders were synthesized via solid state technique. The two types of precursors were prepared and mixed into planetary ballmill, i.e., CeO2 (Sigma Aldrich) with Gd2O3 (Sigma Aldrich) and CeO2 (non-commercial, local product) with Gd2O3 (Sigma Aldrich), namely GDC commercial and GDC non-commercial, respectively. The composite electrolyte powders calcined at temperature of 800°C in the air atmosphere condition. The composite electrolytes were then characterized in terms of its morphology, elemental, phase structure and thermal properties of the powders. The GDC commercial and non-commercial powders both consist of face centered cubic fluorite ceria structure which was confirmed by X-Ray Diffraction (XRD). The peaks are matching well with the cerium oxide JCPDS card No: 34-394. There are no peaks detected for the gadolinium oxide. It indicates that the dopant ion is fully substituted into the CeO2 lattice. The elemental analysis was performed using X-ray Fluorescence (XRF). The microstructures were observed under Scanning Electron Microscopy (SEM). The thermal properties characterizations were performed by using Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) from room temperature to 1500°C. Both powders investigated are suitable for electrolyte IT-SOFC based on their physical and thermal characterization. Among the composite electrolytes investigated, the GDC commercial showed the better performance in terms of their physical and thermal properties.

The purpose of this study are describe the results display of each stage of making augmented reality learning media on the conformation concepts of alkanes and cycloalkanes, analyze the results of the feasibility test of augmented reality learning media on the conformation concepts of alkanes and cycloalkanes. This research uses Research and Development (R & D) method which produces products in the form of AR learning media on the conformation concepts of alkanes and cycloalkanes. The results display of AR learning media is visual characteristic, that is a medium that visualizes the 3D form of each alkane and cycloalkane conformation by realizing a vistual form into a real form. The feasibility test phase and limited trial aim to get assessment, suggestions, and improvements to aspects of learning, material substance aspects, visual communication aspects, and software engineering aspects. The results of the overall feasibility test obtained showed high feasibility with a count of 0.73–0.87. While the results of the limited trials obtained showed high feasibility with a percentage of 75–87.5% feasibility. These results indicate that AR learning media on the alkane and cycloalkane conformation concepts are suitable for use as learning aids

In this work, ZnO (Zinc Oxide) rods, which is a sensitive material for gas detection, are grown on a microcantilever surface by hydrothermal technique. Synthesis of ZnO rods consists of two processes, i.e., a formation of seed layer using Zinc Acetate Dihydrate by a dip-coating and a growth of the ZnO rods using Zinc-Nitrate-Tetrahydrate at a temperature 95°C for time variations of 2 hours, 4 hours and 6 hours. Drying condition for both seed layer and growth of ZnO rods was done at a temperature of 120 oC for 2 hours. The ZnO rods were then characterized by Fourier Transform Infrared (FTIR) in order to investigate the formation of Zn-O bond. The characterization results indicate that the metal oxide correlation is shown in the wavenumber spectrum of 540 cm-1 for a sample with 2-hour growth time, while the wavenumber spectrum of 548 cm-1 and 547 cm-1 for the growth time of ZnO rods for 4 hours and 6 hours. Wavenumber spectrum approximately at 540-548 cm-1 is predicted to be the absorption of the formation of a Zn-O bond. Keyword: Microcantilever, ZnO rods, dip-coating, hydrothermal, growth time dependent.

Environmental monitoring has been one of the key to provide better safety measure in various sectors of life. The most famously featured technology in this area is the gas detecting system. It serves not only in an early-warning application, but also a continuous mean to provide background check of the atmospheric status of a specific area ranges. According to their principals, gas sensors can be separated into two categories; the conductive metal-oxides and the electrochemical-type, with the latter gaining more recognition over the last decade as the future standard component in any gas sensing apparatus. Within this article, the whole concept of an electrochemical gas sensor will be presented, including the basic science and the basic electronical engineering that runs the device. The main concern will be fallen onto a specific amperometric-type sensor as the most common electrochemical sensor in the market. Ultimately, since there are multiple parts that comprise a single electrochemical sensor, a special section will be written within this article to show the array of materials that are responsible to the sensing capabilities of the sensor, particularly in the area of sensitivity and selectivity of gases.

Observation on the effect of adding titanium oxide (TiO2) and magnesium oxide (MgO) on the sintering of α-alumina (Al2O3) has been performed. In this study, technical alumina used as basic material in which the sample is formed by the pressureless sintering/cold press and sintered at 1500°C which is lower than alumina sintering temperature at 1700°C. Elemental analysis, observation of microstructure, hardness, fracture toughness and density measurements were carried out to determine the physical and mechanical properties of alumina. The results indicate a change in the microstructure where the content of the platelet structure are much more than the equilateral structure. At sintering temperature of 1500°C, neck growth occurs at ceramics grain, supported by the results of the density test which indicate perfect compaction has occurred in this process.

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 (Ce0.9Gd0.1O1.95 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%.

The purpose of the work is to obtain size and geometry numerical data of femur bone for designing femoral stem of total hip joint arthroplasy to fit for Indonesian patient with normal hip joint structure. Geometry data of femur bone was taken by both X-ray and CT scan methods. The X-Ray anatomy digital objects were taken from different angles at certain intervals as input data to reconstruct anatomical objects. Slicing of femur bone imaging taken by CT scan has a constant interval. Data obtained from both CT scan and X-ray were compared. A solid model of bone is used as a visual-tactile representation, planning surgery (surgical) and simulation tool for physicians. In this work the data input was used for design of a total hip joint arthroplasty (THA) femoral stem. The work reported in this article is considered as a preliminary stage of the development of total hip joint arthroplasty devices for being fit to local (Indonesian) patients with hip joint disorders. The preliminary designs developed in this work is suit for many kind materials, however, for the implementation into manufacturing works, the use of Titanium Alloys need to consider for appropriate femoral stem designs by taking into account the available of tools and effectiveness of femoral stem production, made of the materials.

Elektrolit berbasis serium seperti GDC10 telah banyak dikembangkan untuk aplikasi sel bahan bakar oksida padatan suhu sedang atau yang dikenal dengan Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC). Kodoping merupakan salah satu cara untuk meningkatkan konduktivitas elektrolit IT-SOFC. Tujuan dari penelitian ini adalah untuk mempelajari pengaruh penambahan kodopan neodimium (Nd) terhadap GDC10 (Ce0,9Gd0,1-xNdxO1,90) dengan rasio molar x = 0,025; 0,050; dan 0,075 terhadap sifat fisis dan elektrokimianya. Neodimium digunakan sebagai kodopan karena dapat menurunkan energi aktivasi, sehingga konduktivitas elektrolit meningkat. Metode sintesis yang digunakan adalah sol gel untuk menghasilkan serbuk GDC terdoping Nd, setelah itu serbuk dibuat pelet. Sampel dikarakterisasi dengan menggunakan X-Ray Diffraction (XRD) untuk mengidentifikasi fasa, Scanning Electron Microscope (SEM) untuk melihat morfologi dan Thermal Gravimetric Analysis (TGA) untuk melihat stabilitas termalnya. Dari hasil penelitian, kalsinasi pada suhu 700 oC selama 5 jam dan sintering pada suhu 1350 oC selama 2 jam diperoleh densitas pelet elektrolit lebih besar dari 95%. Hal ini telah memenuhi syarat sebagai elektrolit sel bahan bakar padatan yang baik. Keseluruhan sampel memiliki struktur kubik dengan ukuran kristal antara 4,26 nm hingga 4,47 nm. GDC10 terdoping neodimium dengan rasio molar x = 0,025 (GDC-Nd0,025) memiliki konduktivitas tertinggi yaitu 0,055 S/cmpada suhu 600 oC. Hasil tersebut menunjukkan bahwa kodoping dapat meningkatkan konduktivitas sel elektrolit GDC untuk aplikasi sel bahan bakar oksida padatan suhu sedang.

Microcantilever-based sensors have been demonstrated to be a high sensitive sensor in sensing application areas of chemistry, physics, biology, and biomedical. To determine the sensor selectivity, the microcantilever surface must be coated by a sensitive layer. In this work, zinc oxide (ZnO) is prepared on the microcantilever surface as a sensitive layer by employing a crystal growth method. To confirm the elemental of ZnO sensitive layer, the coated microcantilever surface is characterized by energy dispersive spectroscopy (EDS). Next, we investigate the response of microcantilever sensor to CO2 gas in dynamic mode operation. The results show that the microcantilever sensitively responds the gas, which is indicated by the change of resonance frequency. Moreover, the consistent sensing behavior with certain resonance frequency shift due to gas response over repetitive cycles is found. The quite small of response and recovery times indicate that the sensing performance of the microcantilever with ZnO sensitive layer has high repeatablility and high reproducibility.

Composite based on gadolinium doped cerium (GDC) co-doped Lanthanum (La), Scandium (Sc), Ytterbium (Yb) were investigated as electrolyte for solid oxide fuel cell (SOFC), namely GDC-La, GDC-Sc, GDC-Yb and GDC-Nd, respectively. The second co-doped La, Sc, Yb and Nd ensured the stability and high ionic conductivity of the GDC ceria-based electrolyte materials for SOFC. The GDC powder was synthesized via sol-gel technique. Then the La-GDC, Sc-GDC, Yb-GDC and GDC-Nd were subsequently prepared by mixing the GDC with La, Sc, Yb, and Nd respectively, through solid-state reaction in ballmill at 200rpm alumina balls. The composite electrolytes were then characterized in terms of its morphology, phase and thermal properties of the powders. Among the composite electrolytes investigated, GDC-Yb powder show higher purity and better dispersion than the others co-doped GDC. TGA analysis present that the addition of co-dopant led to improve thermal resistance and stability of solid electrolyte powders. The results confirm that GDC with co-dopant is promising alternative electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFC).

The effect of micromotion on the shear shielding and size of yielding region in the bone asperity in contact with metal of femoral stem was investigated. The main objective of this work was to gain an understanding of bone wear particleformation mechanism from the two-dimensional finite element model of cementless femoral stem type. To assess the influence of the parameters of interest, different friction coefficients and sliding distance (micromotion)were used in the numerical simulations. Results from the finite element analysis showed that the increase ofthe yielding region is strongly influenced by the rise in sliding distance (micromotion), which is related to the generation of bone wear particle formations. Finite element bone wearparticle formation model, based on strain discontinuities, was therefore proposed for further works. The results obtained in this study can lead to the development of an accurate finite element wearparticle formation mechanism model that would be of use in the assessment of an artificial implant performance and their development.