Judul: Fingerprint, Antioxidant, and Anti-tyrosinase Activity of Fungus Comb Extract
Abstrak: Fungus comb merupakan suatu struktur yang dibuat oleh koloni rayap Macrotermitinae dengan banyak potensi karena mengandung metabolit sekunder seperti steroid, terpenoid, dan saponin, serta senyawa yang memiliki sifat antioksidan dan anti-tirosinase. Tujuan penelitian ini adalah menemukan pola sidik jari serta menentukan kapasitas antioksidan dan aktivitas anti-tirosinase ekstrak fungus comb. Kromatografi lapis tipis (KLT) digunakan untuk menggambarkan pola sidik jari. Pola KLT yang dihasilkan diolah dengan ImageJ dan diubah menjadi densitogram. Fungus comb diekstraksi dengan pelarut n-heksana dan etil asetat. Hasil KLT menunjukkan ekstrak mengandung steroid dan terpenoid serta memiliki sifat antioksidan. Kapasitas antioksidan diuji dengan pereaksi 2,2-difenil-1-pikrihidrazil. Ekstrak n-heksana memiliki nilai kapasitas antioksidan 9,07 mg asam askorbat ekuivalen (AAE)/g ekstrak sedangkan ekstrak etil asetat memiliki nilai 6,04 mg AAE/g ekstrak. Aktivitas anti-tirosinase diuji dengan substrat L-tirosina dan L-3,4-dihidroksifenilalanin (L-DOPA). Ekstrak n-heksana memiliki aktivitas anti-tirosinase lebih baik dengan nilai IC50 1804 µg/mL untuk L-tirosina dan 6784 µg/mL untuk L-DOPA., Fungus comb is a structure made by termite colony Macrotermitinae with lots of potential because it contains secondary metabolites such as steroids, terpenoids, and saponins and compounds containing antioxidant and anti-tyrosinase properties. This study aimed to determine fungus comb extracts' fingerprint pattern, antioxidant capacity, and anti-tyrosinase activity. Thin layer chromatography (TLC) was used to determine fingerprint patterns. The resulting TLC pattern was processed with ImageJ and converted into a densitogram. The fungus comb was extracted with n-hexane and ethyl acetate. TLC results showed that fungus comb extracts contain steroids and terpenoids and have antioxidant properties. The antioxidant capacity assay was carried out with 2,2-diphenyl-1-picrylhydrazyl reagent. N-hexane extract had an antioxidant capacity value of 9,07 mg ascorbic acid equivalent (AAE)/g extract, while ethyl acetate extract had 6,04 mg AAE/g extract. Anti-tyrosinase activity assay was carried out with L-tyrosine and L-3,4-dihydroxyphenylalanine (L-DOPA) as substrates. N-hexane extract had a better anti-tyrosinase activity with IC50 of 1804 µg/mL for L-tyrosine and 6784 µg/mL for L-DOPA.
Keyword: analisis sidik jari, antioksidan, anti-tirosinase, ImageJ, KLT

Judul: Bioactivity of Fungus Comb Extracts from  Subterranean Termite’s Nests of Subfamily Macrotermitinae on Wood Stain Fungi
Abstrak: Indonesia merupakan salah satu wilayah sebaran utama spesies rayap dari subfamili Macrotermitinae (Isoptera: Termitidae). Salah satu keunikan spesies rayap dari subfamili ini adalah sumber makanannya berupa nodul jamur yang tumbuh pada fungus comb di dalam sarang rayap tersebut. Fungus comb tersebut hanya dapat ditumbuhi oleh genus jamur Termitomyces. Hal ini kemungkinan besar terkait dengan aktivitas senyawa kimia pada fungus comb. Penelitian ini bertujuan menentukan ekstrak fungus comb dari sarang rayap subfamili Macrotermitinae teraktif sebagai penghambat pertumbuhan jamur pewarna kayu Aspergillus foetidus. Ekstraksi fungus comb dilakukan secara bertingkat menggunakan n-heksana, etil asetat, metanol, dan air destilata. Masing-masing ekstrak dan larutan kontrol positif (metilen bistiosianat) ditentukan bioaktivitasnya terhadap A.foetidus berdasarkan metode persentase penghambatan pertumbuhan jamur tersebut pada media PDA (Potato Dextrose Agar). Hasil penelitian menunjukkan bahwa semua larutan ekstrak fungus comb memiliki aktivitas terhadap A.foetidus dengan daya hambat pertumbuhan berkisar antara 21,67% sampai 100%. Ekstrak etil asetat dengan konsentrasi 6% menunjukkan daya hambat pertumbuhan A.foetidus tertinggi., Indonesia is one of the main geographical distribution regions for termite species from the subfamily Macrotermitinae (Isoptera: Termitidae). One of the uniqueness of the termite species from this subfamily is that they developed a brain like structure inside their nest, known as fungus comb, as a substrate for growing Termitomyces fungus. On the fungus comb, Termitomyces fungus is the only genus of fungus that can grow. It is suspected that the chemical compounds of the fungus comb inhibited other fungus to be grown. This study aimed to determine the active extract of the fungus comb from the subfamily Macrotermitinae as an inhibitor for the wood staining fungi Aspergillus foetidus growth. Fungus comb extraction was carried out gradualy using n-hexane, ethyl acetate, methanol, and distilled water respectively. Each extract and positive control solution (methylene bistiocyanate) was determined for its bioactivity on A.foetidus based on the method of inhibiting the growth of the fungus on PDA (Potato Dextrose Agar) media. The results showed that all fungus comb extracts had activity in inhibiting A.foetidus growth with inhibition rate ranged from 21.67% to 100%. Ethyl acetate extract with a concentration of 6% showed the highest growth inhibition rate on A.foetidus
Keyword: Aspergillus foetidus, Bioaktivitas, Ekstrak, Fungus comb

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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