Judul: Potensi Antioksidan, Inhibitor Tirosinase, dan Nilai Toksisitas dari Beberapa Spesies Tanaman Mangrove di Indonesia
Abstrak: Indonesia is a country rich in biodiversity. Mangrove is a plant that quite a lot in Indonesia. This research was conducted to determine potency of antioxidant, tyrosine inhibitors, and toxicity from some types of mangrove plants. The result showed that the yield of R. stylosa bark extract was 18.07% and it was the highest yield extract. S. caseolaris fruit extract had the lowest LC50 of toxicity (126.73 μg/mL). S. caseolaris bark extract had antioxidant best value with IC50 of 3.03 μg/mL. This extract also had the best potency of tyrosinase inhibitors with IC50 value of 117.67 mg/mL for monophenols and 364.99 mg/mL for diphenols. Active compounds detected in S. caseolaris extract were tannins, saponin, flavonoid, and phenol hydroquinone. S. caseolaris bark extract was the best extract due to the best ability of antioxidant activity and tyrosinase inhibitory activity.
Keyword: Bogor Agricultural University (IPB), toxicity, mangrove, inhibitors tyrosinase, best extract, antioxidant

Judul: Eksplorasi Potensi Bahan Aktif Berkhasiat Antioksidan Pada Daun dan Buah Mangrove Jenis Sonneratia alba (JE Smith, 1816)
Abstrak: Sonneratia alba has been used traditionally by coastal communities for drugs and foodstuffs. Antioxidants are compounds that was result from plant secondary metabolites and that has been helpful for humans to protect from free radical attack when it consumed. The purpose of this research is to obtain a total phenol values, IC50 concentrations and the relationship of both, from methanol extract of young leaves, old leaves and fruits of Sonneratia alba then to identify the phytochemical content. The experiments antioxidant activity using 1,1-diphenyl-2-pikrilhidrazil (DPPH). Total phenol values in the three extracts showed theres no significantly values. DPPH test showed that IC50 concentrations in the sample extracts are classified into three powerful antioxidants, the young leaf extract showed highest antioxidant activity of 37.43 ppm. Regression between total phenols with IC50 showed no significant. So, there are other compounds that affect the value of IC50. Based on phytochemical test, the chemical components of dried simplicia contained flavonoids, saponins, tannins, and steroids on the three samples.
Keyword: Bogor Agricultural University (IPB), Sonneratia alba, DPPH, leaves, fruits, antioxidants

Judul: Persamaan Geodesik Black Hole dengan Metrik Kerr 4+1 Dimensi dalam Koordinat Waktu Kosmik
Abstrak: Persamaan geodesik black hole dengan metrik Kerr 4+1 dimensi dalam koordinat waktu kosmik merupakan interpretasi lain dari persamaan geodesik black hole dengan metrik Kerr 4+1 dimensi, dimana acuan waktu yang digunakan diubah dari koordinat waktu wajar (proper time) ke dalam koordinat waktu kosmik (cosmic time). Waktu kosmik merupakan koordinat waktu yang dimana pengamat bergerak mengikuti ekspansi dari alam semesta. Penelitian ini merekonstruksi persamaan geodesik black hole dengan metrik Kerr 4+1 dimensi yang telah ditemukan pada penelitian sebelumnya menjadi persamaan geodesik yang memiliki fungsi terhadap dimensi waktu (t). Hasil akhir dari transformasi persamaan dapat digunakan sebagai bahan studi pustaka untuk penelitian lebih lanjut mengenai persamaan geodesik black hole dalam koordinat waktu kosmik.
Keyword: Dimensi ekstra, Metrik Kerr, Persamaan geodesik, Waktu kosmik