Judul: Variation in Natural Durability of Surian (Toona sinensis Roem.) Wood from a Single Tree
Abstrak: Surian (Toona sinensis) merupakan salah satu pohon cepat tumbuh yang banyak ditemukan di Indonesia. Kayunya sudah dijadikan komponen perahu, rumah dan meubel meski baru diperdagangkan secara lokal. Variasi keawetan alami kayu surian masih belum banyak diketahui. Penelitian ini bertujuan mempelajari variasi vertikal dan variasi radial keawetan alami kayu surian dalam satu batang pohon untuk menentukan tindakan pengawetan yang harus diambil dalam rangka pemanfaatan kayu secara maksimal. Contoh uji berupa kayu surian yang mewakili bagian pangkal-tengah-ujung (variasi vertikal atau faktor ketinggian) dan gubal peralihan-teras (cariasi radial atau faktor kedalaman) dalam batang. Sebagai pembanding digunakan kayu pinus. Keawetan alami dievaluasi berdasarkan kehilangan berat dan kerusakan contoh uji setelah dikubur 3 bulan. Hasil penelitian menunjukkan keawetan alami kayu bervariasi menurut ketinggian dan kedalaman batang. Keawetan alami cenderung berkurang dari pangkal ke ujung batang mau pun dari teras ke gubal. Kehilangan berat dipengaruhi oleh faktor ketinggian dan kedalaman, sedangkan kerusakan contoh uji dipengaruhi oleh faktor ketinggian, kedalaman dan interaksi keduanya. Keawetan alami kayu surian secara keseluruhan lebih baik dibandingkan kayu pinus., Surian (Toona sinensis) is one of the fast-growing tree species found in Indonesia. The wood is already used locally as a component for boats, houses and furniture. Since variations in natural durability of this wood are still limited, it is necesary to conduct a study on this aspect. This study aims to investigate variations in natural durability of surian wood, especially from a single tree, both vertical and radial directions in order to determine proper preservative treatment. The test sample was surian wood which represents the bottom-middle-tip as well as the heartwood transition-sapwood. As a comparison, pine wood was utilized. Natural durability of wood was evaluated based on weight loss and damage percentage in cross-section of wood samples after being buried for 3 months. Results showed that natural durability of this wood varies in vertical and radial directions. It tends to decrease from the bottom to the tip of the trunk and from pith (heartwood) to the bark (sapwood). The weight loss percentage was influenced by the height and depth factors, while the damage was influenced by the height, depth and the interaction of these two factors. Overall, natural durability of surian wood is better than that of pine wood.
Keyword: natural durability, pine, radial variation, surian, Toona sinensis, vertical variation

Judul: Variations in chemical components of surian (Toona sinensis Roem.) wood in a single tree
Abstrak: Surian (Toona sinensis Roem.) merupakan salah satu jenis kayu yang pemanfaatannya kurang maksimal. Penelitian ini bertujuan mempelajari variasi vertikal (pangkal dan ujung) dan radial (gubal-peralihan-teras) komponen kimia kayu surian dalam sebatang pohon. Komponen kimia dianalisis mengikuti standar TAPPI. Hasil penelitian menunjukkan komponen kimia kayu surian bervariasi dalam sebatang pohon. Kadar lignin serta kadar ekstraktif larut air panas dan larut etanol-benzena dipengaruhi oleh faktor ketinggian dan faktor kedalaman dalam batang, namun tidak oleh interaksi keduanya; sedangkan kadar holoselulosa, α-selulosa, hemiselulosa dan kadar abu dipengaruhi oleh faktor ketinggian, kedalaman dan interaksi kedua faktor. Secara umum pangkal batang memiliki lebih banyak α-selulosa, zat ekstraktif dan abu dibanding bagian ujung; kayu teras lebih banyak mengandung lignin, ekstraktif dan abu; kayu peralihan lebih banyak hemiselulosa; sedangkan kayu gubal lebih banyak α-selulosa. Jumlah relatif komponen kimia kayu surian adalah 69,47‒75,89% (holoselulosa), 44,69‒59,25% (α-selulosa), 14,91‒28,29% (hemiselulosa), 24,29‒36,46% (lignin), 8,66‒13,30% (larut air panas), 3,58‒4,70% (larut etanol benzena) dan 0,64‒1,44% (abu)., Surian (Toona sinensis Roem.) is a member of lesser-used wood species. This study aimed to investigate vertical (base and tip) and radial (heartwood-transition-sapwood) variations in chemical components of this wood from a single tree trunk. Chemical component analysis was determined following TAPPI standards. Results showed that chemical components were influenced by sample location inside tree trunk. Lignin content, extractive content in hot water and in ethanol-benzene varied vertically and radially, but were not influenced by the interaction of the two factors. Holocellulose, α-cellulose, hemicellulose and ash content varied vertically and radially and were influenced by the interaction. In general, the base of the trunk has the highest cellulose, extractive (in hot water and ethanol-benzene) and ash content compared to the tip. Heartwood has more lignin, extractives and ash; transition wood has more hemicellulose; while sapwood has more α-cellulose. The relative amounts of each chemical component of surian wood are 69.47‒75.89% (holocellulose), 44.69‒59.25% (α-cellulose), 14.91‒28.29% (hemicellulose), 24.29‒36.46% (lignin), 8.66‒13.30% (hot water soluble extractive), 3.58‒4.70% (ethanol benzene soluble extractive) and 0.64‒1.44% (ash).
Keyword: chemical components, radial variation, surian, Toona sinensis, vertical variation

Judul: Model Input-output dalam Masalah Network Flow
Abstrak: Production process is a process, which is done by industry, to transform input into output. According to the type of output and its activity, industry can be classified into various sectors, which are connected to each other. Therefore, a model to analyze the connection among sections is needed. The model is known as input-output model (IO model). IO model presents an IO table, which shows informations about the transaction between goods and services in each economic sector. Furthermore, the IO model also shows that the amount of all input is the same as the amount of all output. In this paper, the transaction of each economic sector in IO table is analyzed using network flow theory. The formulated network flow problem implies that each sector represents partly as a producer and also as a consumer. This paper also solves a minimum cost circulation problem.
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