Judul: Depresan Titik Tuang Berbasis Polimer dan Ester Oktil Oleat.
Abstrak: Depresan titik tuang (DTT) dapat digunakan untuk menurunkan titik tuang minyak mentah. Pada penelitian ini, DTT disintesis melalui esterifikasi asam oleat dengan 1-oktanol dan kopolimerisasi ester oktil oleat yang dihasilkan dengan monomer asam akrilat, akrilamida, atau (2-dimetilamino)etil metakrilat, lalu diuji pengaruhnya pada titik tuang dan perilaku aliran minyak mentah. Campuran dengan pelarut xilena telah dapat menurunkan titik tuang minyak mentah yang tergolong fraksi berat dan penambahan aditif kopolimer ester dapat meningkatkan kemampuan tersebut. Kopolimer ester dengan asam akrilat, misalnya, mampu menurunkan titik tuang sebesar 9 oC pada konsentrasi 1% (b/b). Fungsi aditif dalam menurunkan titik tuang teramati dari nilai viskositas sesaat yang lebih rendah dibandingkan dengan blangko. Oleh karena itu, aditif ini berhasil menurunkan titik tuang dan pada suhu 54 oC masih menunjukkan perilaku aliran tipe pseudoplastik.
Keyword: depresan titik tuang, esterifikasi, kopolimerisasi, perilaku aliran

Judul: Sintesis Depresan Titik Tuang Minyak Bumi Berbasis Asam Lemak dan Glikol.
Abstrak: Pengendapan parafin pada pipa penyalur minyak bumi dapat menurunkan produktivitas minyak bumi sehingga perlu upaya untuk mengendalikan proses pengendapan parafin melalui penambahan depresan titik tuang (DTT). DTT ini disintesis melalui esterifikasi asam lemak dengan glikol menggunakan katalis H2SO4. Kinerja DTT diuji melalui dua cara penambahan asam lemak, yakni sebelum inklusi urea dan setelahnya, dua jenis glikol, yaitu dietilena glikol (DEG) dan polietilena glikol 400 (PEG 400), dan tiga DTT dalam minyak bumi, 0.05%, 0.1%, dan 0.5% b/b). Gugus fungsi yang dicirikan menggunakan spektrofotometer inframerah transformasi Fourier mengindikasikan keberadaan gugus fungsi karbonil ester, hilangnya gugus fungsi karbonil asam karboksilat, dan hilangnya gugus OH. Penurunan titik tuang tidak dipengaruhi oleh komposisi asam lemak, tetapi jenis glikol dan konsentrasi DTT. Penurunan titik tuang terbesar adalah 9 °C pada konsentrasi tertinggi diester asam lemak-DEG dan 6 °C pada konsentrasi tertinggi diester asam lemak-PEG.
Keyword: asam lemak, depresan titik tuang, glikol, minyak bumi

Judul: Biology and ecology of the buffalo fly, haematobia exigua de meijere (diptera:muscidae)
Abstrak: The life history of the buffalo fly was observed at room temperature of 27°-29.5°C and at a relative humidity of 48-68 percent. The eggs hatched after 17-22 hours, with an average of 18 hours. First instar larvae measured 1.25 + 0.16 mm long and 0.27 + 0.037 mm wide. reach the second larval stage. It took 6-12 hours to the second instar larvae measured 2.676 +0.187 mm long and 0.353 +0.028 mm wide. The second instar took about 12-24 hours to reach the third larval stage. The third instar measured 6.833 + 0.189 mm long and 0.919 + 0.051 mm wide. It took about 2-3 days for the third instar to become pupae. Duration of the pupal stage was about 5-7 days before the adults emerged. Under laboratory condition, the buffalo fly completed its life cycle in 9.5 to 10.5 days, whereas under field condition it took 9-14 days with an average of 10.5 days. The growth ratio which was based on the measurements of the cephalo-pharyngeal skeleton of each instar was 1.797. The preoviposition period was 8-12 days and mating usually occurred on the 6th or 7th day. The longevity of the male was 29 days, whereas it was 32 days in the female. The range of egg production under laboratory condition was between 20-139 per female fly. The belly and hind legs of the carabao were the most preferred habitat either during cloudy and cool dry or shiny and warm day. When the weather was clear and the carabao was in the shade, the flies tended to be more distributed particularly on the shoulder, dewlap, back and horns. The carabaos had relatively fewer Musca sp. and Stomoxys calcitrans than cattle; never the less carabaos had a higher infestation of buffalo fly than cattle. Oviposition occured either during the day or night but the buffalo flies were more active during the night than in the day time. The effect of various lengths of exposure time of manure in relation to the oviposition was profound. observed, the maximum number of the buffalo flies was occurred when the dung was exposed for 30 minutes. With increasing time of exposure the number and variety of insects also increase. It was evident that Sepsidae and psychodidae were the most dominant insects emerging from the dung. The number of buffalo flies also increased with increasing
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