Judul: Pirolisis limbah kayu dan bambu yang ramah lingkungan untuk menghasilkan asam asetat
Abstrak: The research goal is to produce liquid smoke through pyrolysis process and to get fractions of potential chemical components from woods and bamboo wastes. These raw materials contain adequate hemicellulose, cellulose and lignin. These studies revealed relationship between type of raw materials and compound composition of liquid smoke products. Results of this research are expected to give benefits as follows: (1) Liquid smoke produced from wood and bamboo wastes through pyrolysis process is able to diversify preservative products, aplication of liquid smoke was done at tuna fish and tofu, (2) Model of pyrolysis kinetics was established from Arrhenius and Tsamba equations to observe influence of pyrolisis time and resident time. From calculation of kinetics constant, it can be calculated activation energy (Ea), pre exponential factor (A), half-life time (t½), while, pyrolysis thermodynamics was obtained from entropy, enthalpy and Gibbs free energy changes. From the three liquid smoke produced from pyrolisis of these raw materials, liquid smoke of bamboo gave the highest liquid smoke residue as much as 61.34%, followed by liquid smoke pine tree by 49.60 % and liquid smoke of teak tree produced 43.78%. This indicated that liquid smoke residue produced during pyrolisis process was dependend on the types of raw materials used. Identification of GC-MS of teak, pine and bamboo dust could provide compounds that mostly derived from acid is group of dominant volatile compounds. Identification of compound group of phenol, acid, ester, ketone, alcohol, furan and so on, then followed by separation process to determine acetic acid compound that potential to be used as natural preservative. Its difference is Arrhenius model focused discussion on the impact of temperature to the kinetics constant in form of particle size without heating rate. Tsamba model focused discussion to the impact of pyrolisis temperature to the yield, pre exponential factor and reverse to the heating rate.
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Judul: Karakteristik Fisikokimia dan Aktivitas Antibakteri Asap Cair dari Limbah Padat Penyulingan Minyak Kayu Putih
Abstrak: Penelitian ini bertujuan menentukan rendemen, menganalisis karakteristik fisikokimia, serta menguji aktivitas antibakteri Escherichia coli dan Staphyloccocus aureus dari asap cair hasil pirolisis limbah padat (daun dan ranting). Pembuatan asap cair dilakukan dengan pirolisis menggunakan suhu 400 oC selama 4-5 jam, kemudian asap cair diendapkan dan disaring untuk pemisahan tar. Pengujian yang dilakukan yaitu analisis karakteristik fisikokimia meliputi berat jenis, keasaman, warna, bau, transparansi dan analisis Gas Chromatography Mass Spectrometer (GCMS) serta aktivitas antibakterinya. Hasil penelitian menunjukan bahwa perbedaan bahan baku memberikan pengaruh terhadap kualitas asap cair yang dihasilkan. Asap cair bagian ranting memiliki kualitas fisikokimia dan aktivitas antibakteri yang lebih baik dari asap cair daun. Berdasarkan hasil GCMS, kandungan asam asap cair ranting lebih dominan dibandingkan asap cair daun. Selain itu, peningkatan konsentrasi asap cair hingga 15% pada setiap jenis bahan dapat meningkatkan aktivitas antibakteri. Asap cair campuran (daun-ranting) memiliki kualitas fisikokimia dan aktivitas antibakteri yang cenderung sama dengan asap cair ranting sehingga dapat menjadi alternatif bahan baku., The objective of this research was to determine the yield, analyze physicochemical characteristics, as well as test the antibacterial activity of Escherichia coli and Staphyloccocus aureus from liquid smoke resulting from the pyrolysis of solid waste (leaf and twig). Liquid smoke was made by pyrolysis using a temperature of 400 oC for 4-5 hours, then the liquid smoke was precipitated and filtered for tar separation. The tests carried out analysis of physicochemical characteristics including specific gravity, acidity, color, odor, transparency and analysis of Gas Chromatography Mass Spectrometer (GCMS) as well as its antibacterial activity. The results show that the difference in raw materials have an effect on the quality of the liquid smoke produced. The liquid smoke of the twigs have better physicochemical quality and antibacterial activity than leaves liquid smoke. Based on the results of GCMS, the acid and phenol content of twig liquid smoke is more dominant than leaf liquid smoke. In addition, increasing the concentration of liquid smoke up to 15% in each type of material can increase the antibacterial activity. Mixed liquid smoke (leaf-twig) has physicochemical quality and antibacterial activity which tends to be the same as twig liquid smoke so that it can be an alternative raw material.
Keyword: antibakteri, asap cair, fisikokimia, limbah padat, pirolisis, antibacterial, liquid smoke, physicochemistry, pyrolisis, solid waste

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf