Judul: Komponen Kimia Kayu Jati (Tectona grand& L. f.) Pada Berbagai Kelas Umur Dari KPH Purwakarta
Abstrak: Various age class of Teak wood (Tectona grandis L J), i.e. the age class of I, 11, I11 and IV were investigated for their chemicals content. The sample were taken from the forest district of Punvukartu in West Java. All chemicals content were determined based on approriate Tappi and ASTM standard. The present research is intented to determine the possibility of reducing the harvesting rotation of teak woodfrom Punvakarta (West Java). It was found that holocellulose, cellulose, a-cellulose, Klasan lignin, Spectrophotometric lignin, hernicellulose, extractive (ethanol : benzene = 1 : 2), ash content, solubili@ in NaOH I%, solubility in cold water and solubility in hat water ranged from 68.69-70.65%, 43.57-45.25%, 37.41-39.1 7%, 24.73-28.94%, 23.99-24.26%, 24.29-27.08%, 3.16-1 0.56% 0.58-0.87%. 13.61-19.32%, 4.82-6.46% and 5.23-6.91 %, respectively. Stutistical evaluation of the chemical content data along with anatomy, mechanics and phjlsical properties indicated that the teak wood from Punvakarta may be harvested at the age class of 111.
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Judul: Komponen Kimia Kayu Jati (Tectona grandis Linn. f.) pada Berbagai Kelas Umur dari KPH Saradan
Abstrak: Kecenderungan menurunnya sumber daya hutan alam dan hutan tanaman serta menillgkahlya kebutuhan kayu di Indonesia, mnendorong untuk meningkatkan efisiensi pemanfaatan kayu. Usaha efisiensi ini dapat bempa pemanfaatan kayu secara keseluruhan untuk menghilaugkan atau menyrangi limbah dan daur yang lebih pendek dengan harapau memenuhi kebutuhan kayu yang meningkat. Peuggunaan kayu secara efesien sangat bergantung pada seberapa jauh pengetahuau terhadap sifat-sifat kayu tersebut. Kayu jati (Tectona grandis Li. f.) sebagai salah satu komoditi terbesar di Pulau Jam merupakan jenis kayn yang paling banyak dipakai untuk berbagai keperluan. Namun, penggunaannya hanya terbatas pada umnr tertentu (masak tebang). Cukup luasnya keguuaan kayu jati tidak nlenuhlp kemungkman dihasilkan produk-produk olahan dari pohon dengan daur yang lebih pendek dengan harapan sifat-sifat yang dimiliki sama dengan pohon dari daur yng lebih paujang. Untuk itu, perlu ditunjangpengetahuan tentang sifat-sifat dasar kayu terutama sifat kimianya. Menurut Achmadi (1990), bauyak sifat-sifat kayu baik laugsung atau tidak langsung berhubungan dengan kimia kayu serta arsitektur penyusnnannya pada peringkat lnakroskopis dan mikroskopis. Dumanauw (1993) mengemukakan bahwa sifat kimia mempunyai pengaruh yang cukup besar terhadap sifat umum suatu kayu. Deugan kata lain, komponen kimia kayu mempunyai arti pentiug katena menentukan kegunaau suatu jenis kayu. Sehubungan deligall sifat ini, maka penelitian ini ditujukan untuk mengetahui kadar komponen kimia jati (Tectona grandis Linn. f.) pada berbagai kela
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Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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