Judul: Schizophyllum commune Fr. As Indonesian National Standard Wood Resistance Test Fungi on Four Kinds of Community Wood: Sengon, Rubber, Tusam, and Mangium
Abstrak: Schizophyllum commune Fr. merupakan jamur pelapuk kayu yang cukup ganas karena dalam beberapa kasus dapat menyebabkan kehilangan berat sampai 70 %. Jamur ini dapat menyerang berbagai jenis kayu (lebih dari 25 spesies kayu), telah tersebar luas terutama di daerah tropis, serta mudah tumbuh dan berkembang pada berbagai kondisi. Jamur pelapuk kayu mempunyai kemampuan menguraikan komponen-komponen sel kayu melalui proses enzimatik dari bentuk yang kompleks menjadi lebih sederhana. Ketahanan kayu sangat dipengaruhi oleh kandungan zat ekstraktifnya meskipun tidak semua zat ekstraktif bersifat racun bagi organisme perusak kayu. Berdasarkan sifat ketahanannya, sebagian besar kayu rakyat memiliki kelas ketahanan yang rendah (kelas III, IV, dan V). Penelitian ini bertujuan untuk mengetahui tingkat ketahanan empat jenis kayu rakyat yaitu kayu sengon (P. falcataria), karet (H. brasiliensis), tusam (P. merkusii), dan mangium (A. mangium) terhadap serangan jamur pelapuk S. commune berdasarkan SNI 01.7202-2006. Parameter ketahanan kayu terhadap serangan jamur S. commune dilihat dari nilai kehilangan bobot contoh uji. Berdasarkan hasil pengujian diketahui bahwa kayu sengon termasuk ke dalam kelas ketahanan IV-V (tidak tahan sampai sangat tidak tahan terhadap serangan jamur) dengan nilai kehilangan bobot sengon longitudinal dan sengon cross berturut-turut adalah 32.2 dan 15.5 %. Kayu karet termasuk ke dalam kelas ketahanan IV (tidak tahan terhadap serangan jamur) dengan nilai kehilangan bobot karet longitudinal dan karet cross berturut-turut adalah 13.8 dan 12.0 %. Kayu tusam dan mangium termasuk ke dalam kelas ketahanan III (agak tahan). Nilai kehilangan bobot tusam longitudinal dan tusam cross berturut-turut adalah 8.0 dan 9.3 %. Sedangkan nilai kehilangan bobot mangium longitudinal dan mangium cross berturut-turut adalah 6.3 dan 6.3 %. Dengan demikian, jenis kayu yang dianjurkan untuk menjadi kayu kontrol dalam pengujian ketahanan kayu terhadap jamur S. commune adalah kayu sengon dengan arah serat longitudinal. Jamur S. commune dapat digunakan sebagai standar dan direkomendasikan menjadi jamur untuk pengujian ketahanan alami kayu karena dapat menyebabkan kehilangan bobot hingga 32.2 % pada kayu sengon dengan arah serat longitudinal.
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Judul: Pengujian Ketahanan Alami Kayu Sengon terhadap Jamur Pelapuk Kayu Schizophyllum commune, Pleurotus djamor dan Pleurotus ostreatus dengan Metode JIS K 1571-2004
Abstrak: Fungi is an organism heterotroft that obtains energy by absorbing food from other organic materials, one of which is wood. Wood destroying fungi lives off wood components, such as cellulose, hemicellulose and lignin which are biochemically overhauled with the help of enzymes. Well know wood in the trade to date approximately 400 types. Around 80–85% of Indonesian woods had low resistance class which it’s very easy attacked by wood decay fungi. For instance Falcatria molucana, Acacia mangium dan Pinus merkusii (Yunasfi 2008). Kinds of it which potentially most decaying off the woods are Schizophyllum commune, Pleurotus ostreatus and Pleurotus djamor. This study aims to determine the potential that three kinds on wood decay fungi and the potential quality of wood to three decay fungi based on JIS K 1571-2004 method. The results showed that all three types of wood rot fungi used in this test has the potential to lower the weight of the wood sample. Fungi are the most potent in lowering weight sengon is S. commune with the percentage reduction in timber weight by 3,7%. P. ostreatus and P. djamor only have the potential to decrease the weight of each of 1,5 and 1,1%. Fungi significantly affect the percentage reduction in timber weight, the percentage weight loss of wood obtained from the results of laboratory tests the durability of wood used as a parameter. From these results it sengon wood into class II (resistant), while according to the Seng (1990) sengon wood balance to class IV–V (not resistance) so it can be said that this research has not succeeded. Discrepancy value of the percentage reduction in weight of wood sample with literature, because they suspected the existence of fungal hyphae into the sample wood so that hamper the final weight after the test sample is fed finished. Based on visual observations indicate multiple replication miselliums of fungi not full to close the wood. Ganerally the sample timber has been attacked fungal discoloration lighter (light brown). Its shows three types of fungi that is used is a white rot fungi
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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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