Prototype Teknologi Siluman (Stealth) Material Organik Penyerap Gelombang Radar Dari Komposit Polimer Chitosan-hidroksiapatit Untuk Aplikasi Peralatan Militer Wilayah Perbatasan

Border regions in Indonesia are still often hit problems with other countries, and in other words it indicates weak military defense systems in the border area. Therefore, Indonesia needs to deploy some special forces on the frontier that uses advanced technology, one of them is the stealth technology. Radar absorbing material plays an important role in this technology. Chitosan and hydroxyapatite believed to resemble a good combination of new organic materials that can be developed as a radar absorbing material. The purpose of this study is to develop a prototype of organic radar absorbing material from chitosan-hydroxyapatite polymer composite. Quality characteristics of the material being analyzed are solution viscosity analysis, FTIR, SEM, material thickness, tensile strength. Ability of material to absorb radar waves was analyzed with reflection loss measurement. The prototype resembles a thin, transparent plastic sheet with a yellowish brown color. Values of thickness ranged from 0.14 to 0.17 mm. This material has a tensile strength values ranged from 1.41 ± 2.82 to 159.33 ± 106.33 kPa. SEM analysis showed a porous and homogeneous structure marked by good interaction between chitosan, PVA, and hydroxyapatite. Value of radar absorption by prototype shown with increasing the value of reflection loss. The optimum values obtained in the film with a mixture of chitosan prototype 2%, 5% PVA, and 0.04 gram hydroxyapatite with an average value of reflection loss -32.0907 ± 4.0763 dB

Pengaruh Lama Pengukusan terhadap Mutu Fisik Beras Pratanak pada Beberapa Varietas Gabah

Parboiled rice processing begins with a process of paddy soaking and steaming. These processes are intended to improve physical quality and lower the glycemic index so it fits for diabetic and diet purposes. Objective of this study was to assess the effect of soaking time and temperature on paddy moisture content and effect of steaming time on milling yield and physical quality of parboiled rice in some paddy varieties. The stages of the research was determination of soaking time and temperature, processing of parboiled rice, milling yield analysis, and physical properties analysis. The result showed that paddy soaking at 60oC takes 3 - 5 hours to reach moisture content of 25 – 30%, whereas at 30oC takes more than 7 hours. Steaming of Ciherang paddy for 20 minutes resulted the highest head rice yield (72.52 ± 5.00%). Parboiling condition that recommended was soaking paddy on 60oC for 4 hours and steaming for 20 minutes using Ciherang paddy variety