Judul: Pengaruh Jenis Alkohol pada Rendemen Sintesis Zink Dialkilditiofosfat
Abstrak: Zinc dialkyldithiophosphate (ZDTP) is an organometallic compound used as an additive in lubrication system. ZDTP was composed of Zn atoms with two dialkyldithiophosphoric acid. The usefulness of ZDTP depends on alkyl content, as for antiwear, antioxidant, anticorrosive, and restrain extreme pressure. ZDTP can be synthesized through two step. Firstly, dialkyldithiophosphoric acid (ADTP) was made from diphosphorus pentasulphide (P2S5) with alcohol. Second, ADTP was reacted with zinc oxide (ZnO), producing ZDTP. The suitability of the ZDTP has been varied by using fourier transform infrared spectrophotometer (FTIR), atomic absorption spectrophotometer (AAS), and high performance liquid chromatography (HPLC). The yield of ZDTP 1-4 were 13.88%, 43.50%, 97.29%, and 77.35%, respectively. The result of FTIR characterization in ZDTP showed P-O-C group absorption at 1000􀵆980 cm-1, PS bond absorption at 650􀵆550 cm-1, and Zn-S bond absorption at 400􀵆300 cm-1 . AAS was used to determine the content of Zn in ZDTP 1-4 with the value of 16.16%, 28.82%, 11.81%, and 17.36%, respectively. Verification of compliance indicators ZDTP were measured by comparing the retention time and HPLC chromatograms. It showed that the measured ZDTP had similar retention time with and authentic commercial ZDTP on the same absorption band despite, low concentrations.
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Judul: Pengaruh Pelarut pada Rendemen Sintesis Zink bis(dibutil ditiofosfat)
Abstrak: Lubricant additives used in Indonesia are still imported. Zink dialkyldithiophosphate (ZDTP) is a multifunctional oil additives, works as an antioxidant, antiwear, anticorrosion, and antiscuff. Synthesis of ZDTP has been widely performed and several methods have been developed. The method used in this study was relatively easy and simple, and the reagents were relatively easy to obtain. Various organic solvents were used in the synthesis, namely n-heptane, diethyl ether, and chloroform. Zink bis(dibutyl dithiophosphate) yield in all three solvents did not differ markedly, 97%, 92%, and 98%, respectively, with reaction time of 12 hours each in both steps. Functional group characterization of Zink bis(dibutyl dithiophosphate) using Fourier transform infrared spectrophotometer showed similar absorption bands for all three solvents. The high performance liquid of chromatography analysis results showed that the retention time of Zink bis(dibutyl dithiophosphate) synthesized using n-heptane, diethyl ether, and chloroform were similar to that of commercial authentic ZDTP.
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Judul: Karakteristik Anatomi Skelet Kepala Buaya senyulong (Tomistoma schlegelii).
Abstrak: Buaya sepit atau senyulong (Tomistoma schlegelii) merupakan jenis buaya asli Indonesia yang berhabitat di sungai-sungai Sumatera, Kalimantan, dan juga pedalaman Sulawesi. Salah satu ciri khas buaya senyulong adalah bentuk moncong yang runcing dan sempit, namun hingga saat ini informasi mengenai struktur skelet kepala buaya senyulong sangat terbatas. Penelitian ini bertujuan untuk mempelajari karakteristik anatomi skelet kepala buaya senyulong yang dikatikan dengan fungsi dan perilakunya. Penelitian dilakukan secara eksploratif dengan melakukan pengamatan, pencatatan, dan pengambilan gambar dari skelet kepala buaya senyulong. Skelet kepala berukuran panjang 70 cm, lebar 29 cm, dan tingggi 17 cm dengan permukaan kasar pada os nasale, os frontale, os maxilla, os mandibula, os lacrimale, os jugale. Jumlah gigi pada buaya ini sebanyak 78 buah, terdiri dari 4 buah gigi premaxila, 16 buah gigi maxila, dan 19 buah gigi mandibula. Pada regio orbitalis ditemukan dua pasang fenestrae temporales yang berkembang baik. Fenestra supratemporale merupakan lubang oval yang membentang di sepanjang os parietale. Fenestra infratemporale berbentuk segitiga dan dibatasi oleh os squamosum, os postorbitale, os jugulare, dan os quadratum. Os mandibula hewan ini mempunyai symphysis mandibularis yang panjang yaitu garis yang melintang di corpus mandibulae. Secara fungsional ukuran symphysis mandibularis berkaitan dengan adaptasi hewan terhadap diet makan.
Keyword: kepala, moncong, Tomistoma schlegelii