Judul: Redistilled Liquid Smoke from Oil-Palm Shells and Its Application as Natural Rubber Coagulant
Abstrak: Abundant oil-palm shells waste which is generated annually as the result of the increasing production of palm oil can be utilized as source of liquid smoke. The acidic property of liquid smoke shows its potency as natural rubber coagulant. The objectives of this study are to redistill liquid smoke at 80, 90, and 100 ºC and also to examine the coagulation property of the RLS as compared to formic acid as a commercial coagulant. During redistillation, two collections of RLS were obtained from each temperature. The first collection was gathered at the first 5 min and the second one was gathered at the next 5 min. Each collection gave 5 L of RLS. The physical properties test showed that the RLS 100 ºC from the second collection was recommended as the natural rubber coagulant. This coagulant produced Wallace plasticity value that met the the Indonesian standard and high plasticity retention index value. The assumption of constituents in RLS which can prevent the storage hardening in rubber was not proven.
Keyword: Bogor Agricultural University (IPB), redistillation, oil-palm shells, natural rubber, coagulation

Judul: Manufacture and Characterization of Liquid Smoke from the Torrefacted Palm Oil Solid Waste
Abstrak: Peningkatan luas areal perkebunan serta jumlah industri minyak kelapa sawit akan menyebabkan meningkatnya jumlah limbah. Penelitian ini bertujuan memanfaatkan limbah padat kelapa sawit berupa cangkang, pelepah, dan tandan kosong kelapa sawit (TKKS) untuk dijadikan asap cair melalui proses torefaksi. Rendemen asap cair yang dihasilkan dari limbah cangkang, pelepah, dan TKKS berturut-turut 37,3%, 42,6%, dan 50,8%. Setelah distilasi, asap cair berwarna kuning transparan, tidak ada bahan terapung, keasaman 4,34−5,04%, kadar fenol 0,4−2,5%, pH 2,42−2,49, dan bobot jenis 0,995−1,021. Mutu asap cair cangkang dan pelepah telah memenuhi mutu 2 SNI 8985-2021, untuk kriteria warna, keasaman, fenol, pH, dan bobot jenis. Asap cair TKKS telah memenuhi beberapa standar, yaitu untuk kriteria warna, keasaman, bahan terapung, dan pH. Bobot jenis asap cair TKKS belum memenuhi standar karena <1,005, demikian pula dengan kadar fenol karena > 2,0%. Hasil analisis kromatografi gas-spektrum massa menunjukkian keberadaan senyawa asam, fenol, dan karbonil. Dengan demikian, asap cair yang diperoleh berpotensi sebagai pengawet makanan dan pestisida
Keyword: food preservative, liquid smoke, palm oil waste, pesticide, torrefaction

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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