Crab's shells of Portunus pelagicus species were used as raw materials for synthesis of hydroxyapatite were used for protection against demineralization of teeth. Calcination was conducted to crab's shells of Portunus pelagicus at temperature of 1000°C for 5 hours. The results of calcination was reacted with (NH4)2HPO4, then dried at 110°C for 5 hours. Sintering was conducted to results of precipitated dried with temperature variations 400–1000°C for a hour each variation of temperature then characterized by X-ray diffractometer and FTIR in order to obtain the optimum formation temperature of hydroxyapatite is 800°C. The hydroxyapatite is then tested its effectiveness in protection against tooth demineralization using acetate buffer pH 5.0 with 1 M acetic acid concentration with the addition of hydroxyapatite and time variation of immersion. The results showed that the rate of tooth demineralization in acetate buffer decreased significantly with the provision of hydroxyapatite into a solution where the addition of the magnitude of hydroxyapatite is greater decrease in the rate of tooth demineralization.

Boundary value problems (BVPs) of anisotropic and exponentially-graded media governed by a diffusion convection-reaction (DCR) equation are considered. The governing equation is of spatially varying coefficients (with an anisotropic diffusion coefficient). The variable coefficients equation is firstly transformed into a constant coefficients equation, from which we derive a boundary integral equation. A boundary element method (BEM) is then constructed to be used for finding numerical solutions to the BVPs. For the computation of the solutions a FORTRAN code is developed. Some examples of problems are solved. The numerical solutions obtained verify the validity of the analysis used to construct the boundary element method with accurate and consistent solutions. The results also show that the BEM procedure elapses very efficient time in producing the solutions. In addition, the results indicate the effect of anisotropy of the media on the solutions.

The research about the fermentation of coffee Coffea arabica using a consortium of probiotic bacteria has been carried out. This study aims to determine the flavor of arabica coffee C. arabica and its chemical composition after the fermentation process. The fermentation time was divided into 3 times, consists of 24 hours, 36 hours, and 48 hours using a container measuring 10 L, each containing 1.5 kg of coffee and 75 mL of rejuvenated probiotic bacteria cultures. Organoleptic testing was carried out to see the panelists preference for the taste of coffee after fermentation. The results showed that coffee with a fermentation time of 48 hours had the best taste. The GC-MS test results showed several compounds were detected after the fermentation process including furan, phenol, propanoate acid, quinic acid, purine, palmitic acid, pyrol, ascorbic acid, linoleic acid, stearic acid, oleic acid, amines, piran, purines, aldehydes, vitamin E, benzadrex, hexene, tocophenols and arachidic acid.

A boundary element method is utilized to find numerical solutions to boundary value problems of exponentially graded media governed by a spatially varying coefficients anisotropic-diffusion convection equation. The variable coefficients equation is firstly transformed into a constant coefficients equation for which a boundary integral equation can be formulated. A boundary element method (BEM) is then derived from the boundary integral equation. Some problems are considered. The numerical solutions justify the validity of the analysis used to derive the boundary element method with accurate and consistent solutions. A FORTRAN script is developed for the computation of the solutions. The computation shows that the BEM procedure elapses very efficient time in producing the solutions. In addition, results obtained from the considered examples show the effect of the anisotropy of the media on the solutions. An example of a layered material is presented as an illustration of the application.

Japanese taro Colocasia esculenta (L.) Schott var. antiquorum is a good export-valued food commodity and is being developed in Indonesia. Lack of availability of taro seedling is one of a limiting factor in development of Japanese taro. In vitro propagation is an alternative to obtain seeds in large quantities and in a relatively short time. In vitro culture is very dependent on composition of media used, especially growth regulators. This study aims to determine effect and to find optimum concentration of green bean sprout extracts Phaseolus radiatus in shoot multiplication of Japanese taro through in vitro. Plantlet were derived from cultures with ± 3 weeks of age. MS media was supplemented with different concentrations of green bean sprout extracts for shoot multiplication experiments. The concentration was used is 0; 0.5; 1; 1.5; 2 ppm and MS + NAA 1.5 ppm + 1.5 ppm BAP as a comparison of synthetic hormones. The parameters observation were number of shoots, wet weight and percentage of live explants. The results showed that MS media with supplemented of 1.5 ppm green bean sprout extract was optimum concentration in Taro shoot multiplication. Therefore, green bean sprout extract can be used as natural growth regulator in media of Taro shoot multiplication.