Advanced Materials Research Vol. 1179

Abstract: Bone tissue engineering has been used in the biomedical field to treat bone defects by implanting scaffolds into bone tissue. However, the currently developed scaffold still needs to be developed to obtain scaffold building materials with good compatible properties and can regenerate damaged bone cells. This study combines PVA/Chitosan polymer with CHA of tuna bone using the porogen leaching method at a calcination temperature of 100°C for 12 hours. The purpose of this study was to determine the physicochemical properties by characterizing XRD, SEM-EDX, FTIR, and the porosity of the scaffold. The results obtained from the results of the PVA/Chitosan/CHA XRD patterns are the formation of the PVA/Chitosan phase at 2θ(°)=19.68, the IR spectrum of the 𝑃𝑂₄³⁻group band and 𝐶𝐻₂ stretching, the ratio mol Ca/P is 1.98, the pore diameter is 1.561 ± 0.07 μm and the porosity is 55.04%. These results indicate that the PVA/Chitosan/CHA scaffold is an amorphous calcium phosphate (ACP) that has the potential for bone tissue engineering.

Abstract: Microwave heating was used with a gas foaming method for fabricating limestone carbonated hydroxyapatite scaffold (SCHA). Carbonated hydroxyapatite (CHA) was produced from limestone as a calcium source using the co-precipitation method. For further treatment, 0.6 gr CHA powder was mixed in 1 ml H₂O₂ solution as a blowing agent. The slurry-foam-like CHA was heated in a microwave with different levels of heating power from 180 W to 720 W. The SCHA samples were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and Scanning electron microscope (SEM). The crystallinity and crystallite size were affected due to different rates of heating power in the microwave-assisted method. The increasing temperature decreased the crystallite size from 37.49 to 33.97(nm). However, other crystallinity trends were observed at 180 W because the lower power heating needed a longer time to be formed SCHA. The different power rates have an insignificant contribution to the morphology of the scaffolds.

Abstract: Bone cement is a material used in many orthopedic surgeries. Polymethyl Methacrylate (PMMA) is one of the acrylic-based bone cement materials. PMMA will be mixed with an activator (N, N-Dimethyl-p-toluidine (DMPT)), initiator (Benzoyl Peroxide (BPO)), radiopacifier / filler (BaSO₄), and Methyl Methacrylate monomer. Once the materials were mixed, the activator react with the initiator to form radicals and activate the bulk polymerization reaction between the MMA monomer and PMMA molecules. The bulk polymerization reaction occurs exothermically and increases the bulk temperature. Barium sulfate (BaSO4) is an inorganic compound that can be acted as both radiopacifier and filler in bone cement. The specific objective of this study was to describe the effect of BaSO₄ in bone cement composite formation. The solid material; PMMA, BPO, and BaSO4 were mixed firstly. The liquid portions; N, N-Dimethyl-p-toluidine (DMPT), and MMA were mixed and then poured into the solids one in a stainless-steel bowl. The bulk temperature was recorded after a one-minute mixing process. The samples were characterized by Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC). The highest setting temperature and setting time were 107.3°C and 10.6 min which was obtained in BaSO₄ content variables of 7% and 11%, respectively. The average molecular weight of the samples was 561.5-1,332.0 kDa. From the DSC result, the glass temperature of the samples was 119.17-119.87°C.

Abstract: Local hyperthermia therapy is one of the cancer treatments by implementing heat from a temperature of 41-45°C on cancer cells. This method is believed to reduce the risk of normal cells around the cancer cells from dying. The form of hyperthermia therapy itself is in ferrofluid. During its development, superparamagnetic nanoparticles of iron oxide have attracted various studies because of their good magnetic properties and good biocompatibility. However, the poor particle interactions and their tendency to aggregation make coatings on superparamagnetic necessary. Therefore, silica coating on the superparamagnetic surface is carried out to reduce the risk of aggregation and increase the biocompatibility of the material. Polyethylene glycol functionalization was also applied to improve the biocompatibility of the material, as well as being a carrier for ferrofluid. The test was carried out using the magnetite co-precipitation synthesis method and the formation of a sol-gel silica coating. Variations applied in this experiment are the effects of TEOS concentration as a source of silica and the ratio of particles to PEG. The addition of silica was proven to increase the value of the magnetic moment to 51.55 emu/g. The addition of TEOS as a source of silica in iron (III) nanoparticles has an effect on increasing the magnetic attraction, decreasing the surface tension value, reducing particle size, and decreasing the SAR value. Functionalization of polyethylene glycol has the effect of reducing the magnetic moment, increasing and decreasing hydrophobicity, increasing the surface tension value, and reducing the particle size of iron (III) oxide nanoparticles. This shows that magnetic nanoparticles coated with silica with polyethylene glycol functionalization are proven to generate heat when given AC current with the SAR value and the highest temperature is found in iron (III) oxide which gets 3ml silica coating with a PEG ratio of 2:5 at a temperature of 32.2°C. and SAR value of 87.63 W/mg

Abstract: This study aims to obtain a better contrast in the film image on X-ray examination of the ossa manus in posteroanterior projection with the addition of an acrylic compensating filter. An investigation was carried out using the phantom manus object on the Quantum CS-2 X-ray apparatus in the examination room 1 of the Margono Soekarjo Hospital (RSMS) by adding acrylic material on the outside of the collimator with a thickness ranging from 2 mm to 22 mm as a determinant of the thickness of the compensation filter. The radiographs were processed by a CR reader and imported into the Weasis software version 2.0.7 to analyze their pixel values. The results showed different compensatory filter thicknesses in the carpal and distal phalanges. An acrylic compensation filter with a thickness of 2.32 cm was considered optimal to compensate for the distal phalanges area and 0.08 cm for the carpal area in the phantom manus with an exposure factor of 55 kV and five mAs.

Abstract: Denture wearing requires loss of teeth through trauma or natural phenomena. The activation of polymerization of polymethyl methacrylate (PMMA) denture base material by methylmethaacrylate (MMA) caused cytotoxic effect and biofilm formation at undercut hindered the mechanical properties and durability of denture. In this study, the effect of guava leaf extract modified coconut shell powder on mechanical properties of hybrid CSP-PMMA denture base composites was investigated. The coconut shell powder (CSP) was obtained from its extracted fiber after dried, grinded and sieved using 80 μm. Guava leaf extract was obtained using ethanolic method. PMMA composites were prepared at variable weight fraction of PMMA+CSP: GLE+MMA using rule of mixture in ratio. The flexural strength, tensile strength, hardness, and toughness properties of the composites at different levels were determined using Universal testing machine of AMETEK EZ 250 model and a shore scale D durometer in accordance with ASTM D – 2240, respectively. The modification of CSP-PMMA by GLE improved the tensile strength, toughness, elongation and hardness by 18.23, 10.52, 68.14 and 1.35 %. Hence the use of GLE in PMMA denture base composites not only enhanced the mechanical behaviours but protect the PMMA denture against biofilm formation. Keywords: Mechanical properties; Guava leave extract, PMMA; Coconut shell fillers.

Abstract: Biodiesel tends to oxidation during the time of storage due to chemical structure, makes deterioration of fuel quality. Hence, the presence in feed stock required to gain standard quality for biodiesel commercialization. Natural antioxidant, mainly oryzanol found in rice bran feed stock, have been worked in biodiesel oxidation synergistic without any additional of synthetic antioxidant. In this work, the potential natural antioxidant has been evaluated by the oxidation stability. The biodiesel exhibited oxidation stability gained the induction period at 3 h by Rancimat method. It was found that the concentration of oryzanol above 300 ppm keep the biodiesel from oxidation. Even though very small amount 3 ppm oryzanol was obtained but contribute as cost implication due to antioxidants are costly chemicals. Otherwise adding synthetic antioxidant making high cost on biodiesel storage and utilization.

Abstract: This research was conducted to compare the characteristics of activated carbon that synthesized via different methods, physical and chemical activation. It was applied to reduce Free Fatty Acids (FFA) in used cooking oil which will be used in the manufacture of biodiesel. Physical activation was carried out by heating dried coconut shell in a tube furnace at 900°C in N₂ gas flowing, by varied the holding time; 2 hours, 3 hours, and 4 hours. Meanwhile, chemical activation was conducted using phosphoric acid solution with various concentrations: 9%, 10%, and 11%. The BET (Brunauer-Emmett-Teller) test was processed to determine the surface area of ​​the activated carbon. The FFA test was conducted to determine the FFA content in treated used cooking oil. The activated carbon with chemical activation has a surface area of ​​260.57 m²/gram, 323.55 m²/gram, and 162.21 m²/gram at concentrations of phosphoric acid 9%, 10%, and 11%, respectively. Meanwhile, for physical activation, the surface area were 278.58 m²/gram, 448.368 m²/gram, and 444.74 m²/gram with variations in heating holding time of 2 hours, 3 hours, and 4 hours, respectively. The lowest levels of FFA are found in cooking oil with a phosphoric acid concentration of 11%, which is 1.505%. The higher the concentration of chemical activator, the greater the adsorption power of an activated carbon. The lowest levels of fatty acids are found in cooking oil with a holding time of 4 hours, which is 1.805%. FFA (Free Faty Acid) test results show that the longer the heating holding time, the better the activated carbon will be.

Abstract: The substitution of Mg/Al hydrotalcite catalyst over the glucose-isomerase is expected to decrease the space-time and reduce the energy consumption of glucose isomerization into fructose. The quality of the Mg/Al hydrotalcite catalyst is determined during the synthesis process. The synthesis has been carried out in the various Mg/Al molar ratio and precipitation times and observed the catalytic activity in the isomerization. Response Surface Methodology (RSM) is used to analyze statistically the optimum condition of the synthesis process. The Mg/Al molar ratio was 1:1 to 4:1 with a precipitation time of 720-1080 min. The characterization of the Mg/Al hydrotalcite catalyst includes the functional groups of the constituent compounds by FTIR, the crystallinity and particle size by (XRD), and the surface area of the catalyst by BET. The RSM results show the optimum condition of the Mg/Al molar ratio and precipitation time to produce the highest mass catalyst product of Mg/Al hydrotalcite catalyst (3,38 g) is 3.34:1 and 984.85 min. The highest degree of crystallinity obtained is 28.70% with the particle size is 10.19 Å. The highest yield and selectivity of the isomerization process are 56.95% and 91.89%, respectively. By the RSM analytical method, the Mg/Al molar ratio and the precipitation time used in this catalyst synthesis do not give a significant effect on the catalytic activity of the isomerization.