Judul: Sintesis Hidroksiapatit Berpori dari Cangkang Keong Sawah (Bellamya javanica) dengan Penambahan Pati Singkong sebagai Porogen
Abstrak: Hydroxyapatite (HAp) was synthesized by mixing Ca(OH)2 with (NH4)2·HPO4 and adding cassava starch as porogen. The method used was wet method (presipitation), by reactioning Ca(OH)2 from snail’s shell with technical (NH4)2·HPO4. Characterizing using X-ray diffractogram (XRD) showed that the sonication treatment of 2, 4, and 6 hours produced various Hap purities. HAp with sonication time of 6 hours gave the highest in purity level, so it was used for synthezing the pored HAp. Pored HAp was formed by adding cassava starch as porogen with concentration at 20 and 30%. Cassava starch was lost in calcination process and it created the pores in HAp. Characterization by XRD showed that the samples formed HAp but still contained some wastes. Identification by scanning electron microscope described the porogened Hap by 30% cassava starch had larger pore, between 13.2 and 46.79 μm. Analisis of infrared spectrum on porogened HAp by 30% cassava starch showed band that the functional groups had patterns. The growth of apatite crystal in in vitro test showed bioactivity of the porogenated HAp.
Keyword: snail’s shell., hydroxyapatite, cassava starch

Judul: Sintesis hidroksiapatit berpori dari cangkang keong sawah (Bellamya javanica) dengan porogen polivinil alkohol dan pati singkong
Abstrak: Hidroksiapatit (HAp) (Ca10(PO4)6(OH)2) merupakan biokeramik yang memiliki komposisi kimia yang sama dengan jaringan tulang. Tujuan penelitian ini ialah menyintesis HAp berpori dengan sumber kalsium dari cangkang keong sawah menggunakan polivinil alkohol (PVA) serta pati sebagai porogen. Metode yang digunakan adalah metode basah (presipitasi) dengan mereaksikan Ca(OH)2 dan H3PO4 85% pada suhu ±40 oC serta pH 10. HAp berpori disintesis dengan menambahkan porogen PVA dan pati dengan nisbah 10%:20%, 15%:15%, dan 20%:10%. Berdasarkan spektrum difraksi sinar-X pada HAp dengan porogen PVA dan pati, fase HAp merupakan fase yang dominan. Selain HAp, terdapat fase lain seperti Ca10(PO4)6CO3 dan Ca10(PO4)3(CO3)3(OH)2. Berdasarkan analisis mikroskop elektron payaran, HAp berporogen yang terbaik adalah PVA dan pati bernisbah 10%:20% dengan ukuran pori maksimum 7.2 μm. Berdasarkan analisis gugus fungsi menggunakan spektrum inframerah transformasi fourier diperoleh gugus fungsi OH-, PO4 3-, dan CO3 2- baik pada HAp tanpa porogen maupun dengan porogen PVA:pati (10%:20%).
Keyword: cassava starch, hydroxyapatite, polyvinyl alcohol, porogen

Judul: Pemanfaatan modul transmitter-receiver untuk pengukuran telemetri unsur-unsur cuaca
Abstrak: Telemetry is transfer of information at a certain radio frequency of the transmitter to the receiver system with air intermediaries. Telemetry system will be useful for the measurement process with the direct method requires measuring device is placed in a location difficult to monitor at all times. A universal transmitter-receiver modules in available the market have different characteristic and specifications depend on manufacturers. The antenna is modified to maximize the distance of data transmission. The separation time between the incoming data is detected down to 0.32 second and the minimum signal pulse length can be detected by the module is 0.3 second. The farthest distance of data transmission obtained after modifying the antenna is 260 meters, maximum results are obtained if the modification is only made to any one of the modules. Faulty measurement due to timming conflict and power supply instability are about 3 % of the whole measurement.
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