Judul: Sisntesis Silikon Karbida (SiC) dari Silika Sekam Padi dan Karbon Kayu dengan Metode Reaksi Fasa Padat
Abstrak: The agricultural waste such as rice husk and meubel waste such as powder wood does not used in an optimal fashion for functional material. Silica were synthesized from rice husk by burning and refining. Rice husk contains silica ± 10,5% with purity 95,1%. Carbon were synthesized from powder wood in reactor. The aim of our research was synthesis silicon carbide (SiC) from rice husk and wood. Silica and carbon mixture with ratio 5/3 and 1/3 were reacted by solid state reaction. SiC ceramic was produced by milling, hidrothermal, and sintering. The product was analyzed by X-Ray Diffraction, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Ultra Violet -Visible spectrometry, and I-V meter. The Size of crystal vary from 18 to 200 nm. The SiC ceramic is semiconductor material that can used to electronic aplication.
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Judul: Penambahan magnesium berlebih dalam menghasilkan silikon murni dari sekam padi sebagai bahan semikonduktor
Abstrak: Rice is one of the most important cultivated plants in human civilization. Rice is also one of the main carbohydrate source the majority of the population in Indonesia. Central Statistics Agency (BPS 2012), estimates that in 2012 rice production reached 68.59 million tons, up by 2.84 million tonnes (4:13%) than in 2011. Seeing this, then it will appear in the form of agricultural waste rice husk. Most of the waste generated from the processing of rice had only burned or thrown away (Azadi et al 2010). Utilization of rice husk furnace developed by IPB since 2007, generating more waste in the form of waste rice husk (Irzaman et al 2007). Rice husk charcoal is known to contain at 95.14% silicon dioxide (Supaman et al 2010) and has the potential to produce pure silicon with a rate 40.78% (Hikmawati 2010) and 42.29% (Ahmad L 2012). This study aimed to examine the characteristics of silicon powder obtained from rice husk by chemical reduction method, which reduces the silicon dioxide using magnesium (Mg) powder to vary the ratio of the amount of silicon dioxide with magnesium and washing with a solution of HCl in the purification. Silicon dioxide and silicon obtained will be analyzed using X-Ray Difraction (XRD), Scanning Electron Microscope-Energy Distersive X-Ray (SEM-EDX), LCR meter and I-V meter. Manufacture of silicon through three (3) phases, husk charcoal, silicon dioxide and silicon. Husk charcoal through several stages. At first the rice husk is dried with the aid of sunlight with the purpose of accelerating the combustion process. Then the rice husks were weighed at 5000 grams (5 kg), entered into a husk furnace and continued with the process of burning, then the rice husk charcoal weighed. In this process produced rice husk for 1440 grams (1.44 kg). Rice husk as much as 40 grams put in porcelain dish and baked in a kiln at a temperature initially 400 °C for 2 hours, subsequent heating to temperatures of 1000 °C for 1 hour with the temperature rising rate setting by 1 °C/minutes and 5 ° C/minutes. After the ash obtained by burning weighed, then washed rice husk ash using hydrochloric acid (HCl) 3% technical which 12 mL of HCl 3% for 1 gram of technical rice husk ash, then heated over a hotplate with temperature settings 200 °C and stirred with magnetic stirrer at a speed of 240 rpm for 2 hours. Subsequently washed with hot distilled water (temperature of about 90-100 °C) repeatedly until acid-free (tested with litmus paper), and then filtered through ash-free paper. Screening results (residue separated from the filter paper) is inserted in the porcelain dish is then heated in a furnace at temperatures of 1000 °C for 1 hour with a temperature rise of 1 °C/minutes and 5 °C/minutes until the silicon dioxide remaining white. The samples were cooled in the furnace and weighed, then the result is tested SEM-EDX, LCR meter and I-V meter (Ahmad L 2012). The next process is to get silicon, silicon dioxide mixed with magnesium powder with a reductant that vary the ratio ranging from ratio
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Judul: Beberapa aspek toxoplasmosis pada domba
Abstrak: Toxoplasmosis merupakan penyakit yang disebabkan oleh infeksi protozoa yaitu Toxoplasma gondii. Menurut Kudo (1960), Toxoplasma digolongkan dalam filum Protozoa, sub filum Plasmodroma, kelas Sporozoa, sub kelas Telosporidia, ordo Haemosporidia, famili Babesiidae dan genus Toxoplasma. Selanjutnya Levine et al. (1980) dalam Thomas Cheng (1986), memngklasifikasikan Toxoplasma sebagai berikut : filum Apicomplexa, kelas Sporozoa, sub kelas Coccidia, ordo Eucoccidiida dan sub ordo Eimiriina dengan genus Toxoplasma. Toxoplasma gondii berkembang biak secara seksual dan aseksual. Stadium seksual terjadi di dalam epitel usus ku- cing rumah dan famili Felidae lainnya, sedangkan perkembang biakkan secara aseksual terjadi pada induk semang antara yaitu carnivora, herbivora dan mamalia (Levine, 1973). Kucing mengeluarkan ookista yang belum bersporulasi dalam feses selama 3 10 hari. Hal Ini terjadi setelah kucing tersebut memakan tikus yang telah terinfeksi bradizoit atau trofozoit atau mencerna ookista (Dubey dan Frenkel, 1976 dalam Georgi, 1980). Induk semang antara dapat terinfeksi Toxoplasma gondii bila tertulari ookista bersporulasi dari feses kucing, takhi- zoit atau bradizoit yang terdapat dalam jaringan induk semang antara yang lain, dapat juga terjadi karena terinfeksi takhizoit melalui penularan secara transplasental (Soulsby 1982). Dalam imunitas terdapat satu hal yang menarik yaitu kemampuan Toxoplasma untuk bertahan dalam makrofag yang seca- ra umum dapat membunuh organisme ekstraselular. Menurut Ian Tizzard (1981), respon kekebalan yang perta- ma dari tubuh terhadap parasit Toxoplasma gondii adalah res- pon kekebalan selular (CMI response). Sebagian besar infeksi oleh Toxoplasma gondii tidak menunjukkan gejala klinis yang jelas. Pada domba gejala klinis yang dapat terlihat berupa demam, dispnoe. tremor secara umum dan kadang-kadang terlihat adanya inkoordinasi gerak. Tetapi gejala yang paling umum terjadi adalah plasentitis diikuti abortus atau terjadi kematian foetus pada saat 3 atau 4 minggu terakhir dari kebuntingan. Selanjutnya pada domba gejala dari dikatakan juga gejala yang dapat terlihat betina adalah "circle walking" yang merupakan encephalitis (Soulsby, 1982)…dst
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