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This paper presents the stochastic analysis of finding the feasible trajectories of robotics arm motion at obstacle surrounding. Unknown variables are coefficients of polynomials joint angle so that the collision-free motion is achieved. ãk is matrix consisting of these unknown feasible polynomial coefficients. The pattern of feasible polynomial in the obstacle environment shows as random. This paper proposes to model the pattern of this randomness values using random polynomial with unknown variables as coefficients. The behavior of the system will be obtained from zero distribution as the characteristic of such random polynomial. Results show that the pattern of random polynomial of avoiding collision can be constructed from zero distribution. Zero distribution is like building block of the system with obstacles as uncertainty factor. By scale factor k, which has range, the random coefficient pattern can be predicted.

Curcuma xanthorrhiza Roxb, known as Temulawak or Javanese ginger, is a plant species. Its rhizomes are used as a medicinal herb. It contains curcumin as an active compound and ethereal oils mainly consisted of sesquiterpenes. In this work, Curcuma xanthorrhiza Roxb ethanolic extract was micronized with an addition of PVP using supercritical antisolvent (SAS) method. The ethanolic extract was obtained from dried Curcuma xanthorrhiza Roxb using soxhletation. For the micronization, the extracted compound solvent was a mixture of acetone and ethanol (90:10 (v/v)), while the supercritical CO2 was used as an antisolvent. The effect of operating conditions on the particle size and morphology was evaluated. Through this method, spherical Curcuma xanthorrhiza/PVP particles with mean diameter ranging from 191 ± 70 nm to 178 ± 57 nm were successfully formed. The particle size not significantly decreased as the pressure increased from 8 12 MPa. The addition of PVP is very effective to reduce the particle size, increase the solubility, and enhance the bioavailability of Curcuma xanthorrhiza extract. This work has the potential to improve the use of Curcuma xanthorrhiza in pharmaceutical and nutraceutical applications.

Extraction by using supercritical CO2 has been extensively developed to extract materials that are easily decomposed at high temperatures. Therefore, in this study extraction of valuable compounds (such as: carotenoids and fatty acids) from macroalgae of Eucheuma cottonii and Gracilaria sp was carried out experimentally with supercritical CO2 and mathematical model of Broken and Intact Cells (BIC) and Chrastil model. The result with BIC model is compared with the experimental result that has been done. Extraction was conducted at various pressures of 15, 20, and 25 MPa, temperature of 40, 60, and 80 ºC, CO2 flow rate of 6 mL/min, and ethanol concentrations for cosolvent of 5 %, 7.5%, and 10% CO2 flow rate. The content of extract was analyzed by using a Spectrophotometer UV - Vis and HPLC. The total yield of extract on Eucheuma cottonii was about 0.01623-0.03752 gr extract/gr sample at operating conditions 15 MPa pressure, temperature 60 ºC, and ethanol flow rate of 10%. The total yield of the extract on Gracilaria sp was 0.1982-0.4237 gr extract/gr samples, at operating conditions 15 MPa pressure, 60 ºC temperature, and ethanol flow rate 7.5% CO2 flow rate. The solubility of Eucheuma cottonii are greater than Gracilaria Sp with constant of Chrastil k, a, and b that are: 2,52; 0,911; and-27,66 at operating conditions. Broken and Intact Cells model could also describe well for extraction yield. The best fitting parameters in BIC model depends on condition at extraction process, such as : 0.45 – 0.46 for f, 0.5 - 0.75 for Xc, and 0.15 - 0.4 for K value..

Extraction of phytochemical compounds (such as β-carotene, linoleic acids, carrageenan, and polyphenols) from algae Eucheuma cottonii and Gracilaria sp with supercritical CO2 followed by subcritical water has been investigated. Supercritical CO2 extraction was carried out at pressure of 25 MPa, temperature of 60°C, CO2 flowrate of 15 ml/min, and ethanol flowrate of 0.25 ml/min. To determine the content of carotenoids and linoleic acids, the extracted compounds were analyzed using a spectrophotometer UV-Vis. The residue of algae starting material was subsequently extracted by subcritical water at pressures of 3, 5, and 7 MPa, and temperatures of 120, 140, 160, and 180 °C. Carrageenan extracted by subcritical water was analyzed using Fourier Transform Infra Red (FTIR), while the total phenolic compound was analyzed with UV-vis spectrophotometer. Moreover, the antioxidant efficiency of extract was also examined by DPPH assay method. Based on the analytical result, β-carotene and linoleic acid content in Eucheuma cottonii were 209.91 and 321.025 μg/g sample, respectively. While β-carotene and linoleic acid content in Gracilaria sp were 219.99 and 286.52 μg/g sample, respectively. The optimum condition of subcritical water extraction was at 180°C and 7 MPa. At this condition, the highest TPC content in the extract from Eucheuma cottonii and Gracilaria sp were 18.51 mg GAE/g sample and 22.47 mg GAE/g sample, respectively; while the highest yield of carrageenan extracted from Eucheuma cottonii and Gracilaria sp were 61.33 and 65.54 g/100 g dried algae, respectively. At the same condition, the antioxidant efficiency was 0.513 min-1 for Eucheuma cottonii and 0,277 min-1 for Gracilaria sp. Based on the results the extraction method effectively separated non-polar and polar compounds, then increased the antioxidant efficiency of extract.

Ceria oxide (CeO2) is widely used as catalyst with high oxygen storage capacity at low temperature. The addition of zirconia oxide (ZrO2) to CeO2 can enhance oxygen storage capacity as well as thermal stability. In this work, ceria zirconia oxides has been synthesized via a low temperature solvothermal treatment in order to produce ceria zirconia oxides composite with high oxygen storage capacity as electrolyte of solid oxide fuel cells (SOFC). Under solvothermal conditions, solvent may control the direction of crystal growth, morphology, particle size and size distribution, because of the controllability of thermodynamics and transport properties by pressure and temperature. Water, mixed of water and ethanol (70/30 vol/vol), and mixed of water and ethylene glycol (70/30 vol/vol) were used as solvent, while Ce(NO3)3 and ZrO(NO3)2 with 0.06 M concentration were used as precursor. The experiments were conducted at temperature of 150 °C and pressure for 2 h in a Teflon-lined autoclave of 100 mL volume. The synthesized products were dried at 60 °C for 6 and 12 h and then calcined at 900 °C for 6 h. The particle products were characterized using SEM, XRD, TG/DTA, and Potentiostat. The results showed that the morphology of particles formed were affected by the solvent. Solid plate shaped particles were produced in water, and tend to be pore with the addition of ethylene glycol. The addition of ethanol decreased the size of particles with sphere shaped. The XRD pattern indicated that ceria-zirconia oxides particles are uniformly distributed in the structure to form a homogeneous solid solution. Based on the electrochemical analysis, ceria zirconia oxides produced via solvothermal synthesis had high conductivity ion of 0.5594 S/cm, which is higher than minimum conductivity ion requirement of 0.01 S/cm for SOFC electrolyte. It indicated that ceria zirconia oxides produced via solvothermal synthesis is suitable for SOFC electrolyte.