Judul: Antioxidant Properties Extractive Substances of Manglid Tree Leaves (Magnolia sumatrana (Miq.) Figlar & Noot.)
Abstrak: Pemanfaatan pohon manglid (Magnolia sumatrana (Miq.) Figlar & Noot.) tidak hanya terbatas pada penggunaan kayunya, melainkan pada bagian pohon lainnya seperti daun, kulit, dan akar dengan memanfaatkan kandungan kimia yang terdapat di dalam pohon tersebut. Penelitian ini bertujuan untuk mengetahui kadar ekstraktif daun manglid, mengukur aktivitas antioksidan, dan menganalisis komponen senyawa kimia yang terkandung di dalam fraksi teraktif. Serbuk daun manglid diekstraksi dengan metoda maserasi menggunakan pelarut aseton. Ekstrak aseton yang diperoleh difraksinasi secara bertingkat dengan menggunakan pelarut n-heksana, etil eter, dan etil asetat. Masing-masing fraksi selanjutnya dilakukan uji antioksidan. Fraksi teraktif dianalisis dengan GC-MS untuk mengetahui kandungan kimia yang ada di dalam fraksi tersebut. Kadar ekstraktif daun manglid yang diperoleh dalam penelitian ini adalah 4,11%. Hasil uji antioksidan menunjukkan bahwa fraksi etil asetat merupakan fraksi yang paling aktif sebagai antioksidan dengan nilai IC50 545,34 ppm. Hasil analisis kimia terhadap fraksi etil asetat menunjukkan bahwa senyawa yang diduga mengandung bioaktivitas antioksidan, yaitu oplopenone (1,57%) dan Bis(2-ethylhexyl) phthalate (9,96%)., The utilization of the manglid tree (Magnolia sumatrana (Miq.) Figlar & Noot.) is not only limited to the use of its wood, but also other parts of the tree such as leaves, bark, and roots by utilizing the chemical content contained in the tree. This study aims to determine the extractive content of manglid leaves, measure antioxidant activity, and analyze the components of chemical compounds contained in the most active fraction. Manglid leaf powder was extracted by maceration method using acetone as solvent. The acetone extract obtained was gradually fractionated using n-hexane, ethyl ether, and ethyl acetate as solvents. Each fraction was then tested for antioxidants. The most active fraction was analyzed by GC-MS to determine the chemical content in the fraction. Manglid leaf extractive content obtained in this study was 4,11%. The antioxidant test results showed that the ethyl acetate fraction was the most active fraction as an antioxidant with an IC50 value of 545,34 ppm. Chemical analysis of the ethyl acetate fraction showed that the compounds suspected of containing antioxidant bioactivity were oplopenone (1,57%) and Bis(2-ethylhexyl) phthalate (9,96%).
Keyword: antioksidan, Bis(2-ethylhexyl) phthalate, daun manglid (Magnolia sumatrana (Miq.) Figlar & Noot.), ekstrak aseton, oplopenone, antioxidant, Bis(2-ethylhexyl) phthalate, manglid leaf (Magnolia sumatrana (Miq.) Figlar & Noot.), acetone extract, oplopenone

Judul: Anti-termite Properties of the Extractive Substance of Magnolia sumatrana (Miq.)) Against Subterranean Termites (Coptotermes curvignathus Holmgren).
Abstrak: Manglid (Magnolia sumatrana Miq.) merupakan salah satu jenis tanaman yang banyak dikembangkan di hutan rakyat Jawa Barat. Jenis ini relatif cepat tumbuh dan termasuk kelas awet II, sehingga memiliki ketahanan alami terhadap organisme perusak kayu. Penelitian ini bertujuan untuk mengetahui kadar ekstraktif kulit kayu manglid serta mengukur bioaktivitas zat ekstraktif tersebut terhadap rayap Coptotermes curvignathus Holmgren dan menganalisis komponen senyawa kimia yang terkandung di dalam fraksi teraktif. Ekstrak aseton yang diperoleh melalui ekstraksi dengan metode maserasi, difraksinasi secara bertingkat dengan pelarut n-heksan, etil eter, etil asetat. Analisis kimia dilakukan terhadap fraksi yang paling aktif dengan alat GC-MS. Fraksi etil asetat memiliki persentase mortalitas rayap rata - rata tertinggi sebesar 55,47 % serta persentase kehilangan berat kertas selulosa rata - rata terendah sebesar 24,89 %. Senyawa yang diduga mengandung bioaktivitas anti-rayap, yaitu (+)spathulenol dan (-)- Caryophyllene oxide., Manglid (Magnolia sumatrana Miq.) is a plant that is widely developed in the community forests of West Java. This species is relatively fast growing and has durable class II, so it has natural resistance to wood destroyers. This study aims to determine the extractive content of the manglid bark and to measure the bioactivity of the extractive substance against the termite Coptotermes curvignathus Holmgren and to analyze the components of chemical compounds contained in the most active fraction. The acetone extract obtained by extraction by maceration method was fractionated in stages with n-hexane, ethyl ether, and ethyl acetate as solvents. Chemical analysis was carried out on the most active fraction by means of GC-MS. The ethyl acetate fraction had the highest average termite mortality percentage of 55.47% and the lowest percentage of cellulose paper weight loss was 24.89%. The compounds suspected to contain anti-termite bioactivity are (+)spathulenol and (-)- Caryophyllene oxide.
Keyword: Ekstrak aseton, Kulit kayu manglid (Magnolia sumatrana Miq.), Rayap tanah (Coptotermes curvignathus), Bioaktivitas anti-rayap, Mortalitas, Kehilangan berat, Acetone extract, Manglid bark (Magnolia sumatrana Miq.), Subterranean termites (Coptotermes curvignathus), Anti-termites’ properties, Mortality, Weight loss

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model