Judul: Process engineering of langsat fruit peel (Lansium domesticum var. langsat) extraction as antibacterial and antioxidant
Abstrak: Langsat, a fruit plant in the family of Meliaceae, has long been used in traditional medicine to treat fever, diarrhea, malaria, and tumor. This study aims to obtain the optimum extraction condition and method of langsat fruit peel with the best antibacterial and antioxidant activities. The methods used to determine activities were agar diffusion method, dillution method for MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) for antibacterial and DPPH (1,1-diphenyl-1-picrilhydrazyl) for antioxidant activity. Solvents used in the maceration extraction were hexane (non polar), ethyl acetate (semi-polar) and ethanol (polar). Solvent that gave the best antibacterial and antioxidant activity was further used for the microwave extraction. Conventional extraction methods namely reflux and maceration were then compared to microwave extraction. The microwave power and extraction time was determined based on the highest total phenol extract of langsat fruit peel. The best extraction method was used to optimize the extraction process with response surface method to determine the optimal conditions for the extraction of langsat fruit peel. The results showed that ethanol extracts have the highest antibacterial and antioxidant activity compared to other extracts. The MIC and MBC values of ethanol extracts were 62.5 and 125 ppm for bacteria S. aureus, while the bacteria E. coli with value of 500 and 1000 ppm, respectively. The antioxidant activity of ethanol extract DPPH method has IC50 value of 77.60 ppm. Microwave with power of 400 watt for 3 minutes, produced the highest total phenol extract. Extraction with microwave produced phenol with a total of 13.92% and 22.64%, higher than extraction with reflux and maceration. The optimum extraction of langsat fruit peel was obtained at the microwave power of 336.56 watts and for extraction time of 3.24 minutes, which resulted in a total phenolic extract of the langsat fruit peel 44.07 mg TAE/g. The validation results experimentally showed the value of total phenols 0.66% smaller than predicted. Validation results showed an increase in antibacterial and antioxidant activity than before the optimization, the MIC and MBC values for S. aureus were 31.25 and 62.5 ppm, whereas E. coli with value of 125 and 250 ppm. The antioxidant activity of the validation result has IC50 value of 47.44 ppm.
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Judul: Pengaruh Fraksionasi pada Aktivitas Antioksidan Ekstrak Kulit Buah Langsat (Lansium domesticum)
Abstrak: Langsat (Lansium domesticum) fruit’s peel has been reported to have antioxidant activity but the active compound has yet to be verified. The study objectives were to evaluate antioxidant activities from the crude extract of langsat fruit’s peel and its fractions. The crude extract was obtained through maceration method in 70% ethanol and ethyl acetate. The antioxidant activity was tested by 2,2-diphenyl-1-picrilhydrazil method. The extract with the best activity was further fractionated with the best eluent obtained. The best antioxidant activity was showed by crude 70% ethanol extract with 50% inhibition concentration (IC50) value of 372.90 ppm. The phytochemical compounds in the extract were tannins, flavonoids, alkaloids, and saponins. The fractionation was done by using column chromatography via step gradient elution with at combination of n-hexana and ethyl acetate with increasing polarity giving. 12 fractions which were further tested for their antioxidant activities. However, all fractions did not have antioxidant activities as the inhibition percentage were below 50%.
Keyword: Lansium domesticum, phytochemicals, fractionation, antioxidant

Judul: Analisis Struktur Atas Gedung Diploma IPB terhadap Beban Gempa Berdasarkan SNI 03-1726-2002 dan SNI 03-1726-2012
Abstrak: Gedung Diploma IPB masih menggunakan SNI 03-1726-2002 dalam perencanaan strukturnya. SNI tersebut kemudian diubah seiring dengan keluarnya peraturan baru yang termuat dalam SNI 03-1726-2012. Tujuan dari penelitian ini adalah mengetahui ketahanan struktur atas gedung Diploma IPB terhadap beban gempa ditinjau berdasarkan waktu getar alami dan partisipasi massa, mengetahui besarnya gaya geser dasar seismik, dan membandingkan besarnya simpangan berdasarkan kedua SNI. Partisipasi massa arah X yang dihasilkan yaitu sebesar 0.9417 pada modal ke 9 dan 0.9006 pada modal ke 12 pada arah Y. Kedua nilai tersebut telah memenuhi kedua standar SNI. Waktu getar alami telah memenuhi standar SNI 2002, namun belum memenuhi standar SNI 2012. Gaya geser dasar dinamik yang dihasilkan berdasarkan SNI 2012 sebesar 1599.6606 kN akibat gempa arah X dan 1223.5794 kN akibat gempa arah Y, sedangkan berdasarkan SNI 2002 untuk arah X sebesar 1544.5109 kN dan untuk arah Y sebesar 1544.8304 kN. Simpangan antar lantai telah memenuhi persyaratan kedua standar SNI. Struktur Gedung Diploma IPB telah memiliki kekakuan yang cukup dan terhitung boros, sehingga seharusnya dapat direncanakan dengan lebih hemat biaya.
Keyword: beban gempa, gaya geser dasar, simpangan, struktur atas