Judul: Karakteristik Kimia Kayu Reaksi Ulin (Eusideroxylon zwageri T. et B.)
Abstrak: Reaction wood which formed in hardwood generally has a lower klason lignin content, higher acid soluble lignin content, and higher syringil unit than opposite wood. Ulin wood (E. zwageri) contains high klason lignin and low acid soluble lignin contents which closed to lignin characteristic of softwood. This experimental aimed to study the difference of chemical characteristic of reaction wood (klason lignin content, acid soluble lignin content, and lignin monomer composition) and polysaccharides content which formed in E. zwageri stem. Visually, the reaction wood part was formed in upper side of leaning stem. Klason lignin content in reaction wood part was lower (32.71%) than opposite wood part (33.74%). However, the lowest lignin content was found in the side wood part (28.15%). Lignin of E. zwageri was composed by syringyl and guaiacyl monomer with average of syringil to guaisyl ratio 0,2. Acid soluble lignin content in E. zwageri was very low (0.69%) that positively correlated with the proportion of syringil unit in lignin. Polysaccharide content of reaction wood part (63.66%) was higher than opposite wood part (62.88%), but the highest content polysaccharides presented in the side wood part (64.19%).
Keyword: Polisaccharide, syringil-guaiasyl ratio, lignin, E. zwageri, reaction wood

Judul: Chemical and Physical Properties of Melinjo Reaction Wood (Gnetum gnemon Linn.)
Abstrak: Kayu reaksi terbentuk selama pertumbuhan pohon yang ditandai dengan riap tumbuh yang lebih lebar dengan empulur yang tidak tepat berada di pusat lingkaran batang. Kayu reaksi pada jenis kayu daun jarum dan kayu daun lebar dapat berbeda dengan kayu normal dalam sifat kimia, fisis, dan mekanis kayu. Pohon Melinjo (Gnetum gnemon Linn.) adalah tanaman berbiji terbuka (Gymnospermae), tetapi memiliki beberapa sifat yang menyerupai kayu dari Angiospermae. Tujuan penelitian ini adalah untuk menguji kadar komponen kimia, proksimat, dan sifat fisis kayu reaksi melinjo (posisi kayu reaksi dan kayu samping) dibandingkan dengan kayu oposit (kayu normal). Sifat kimia kayu reaksi yang terbentuk pada kayu melinjo ini menyerupai kayu reaksi tekan dengan kadar lignin lebih tinggi dan kadar selulosa lebih rendah dibandingkan dengan kayu oposit. Sifat proksimat kayu melinjo memiliki keragaman relatif kecil. Nilai kalor sampel kayu melinjo berkisar 4060-4167 kkal/kg, dan nilai kalor tertinggi dihasilkan dari bagian kayu samping yang sejalan dengan tingginya kadar lignin dan karbon terikat dengan kadar zat terbang hampir sama. Kerapatan dan berat jenis kayu pada bagian kayu reaksi, kayu samping dan kayu oposit hampir sama sebagai akibat kecilnya keragaman kadar komponen kimia pada ketiga bagian kayu tersebut., Reaction wood is formed during tree growth which is characterized by wider increments with the pith not centered in the center of the stem circle. The reaction wood formed in the softwood is different from the broad leaved. Furthermore, it can differ from normal wood in chemical, physical, and mechanical properties of wood. Melinjo tree (Gnetum gnemon Linn.) is categorized as an open seeded plant (Gymnospermae) but melinjo wood has several properties that resemble from Angiospermae. The purpose of this study was to examine the chemical components, physical properties, and to analyzed the proximate of melinjo reaction wood (position of reaction wood and side wood) compared to opposite wood (normal wood). The chemical properties of the reaction wood formed on melinjo wood resembles that of tension reaction wood with higher lignin content and lower cellulose content compared to opposite wood. The proximate analysis of melinjo wood has a relatively small diversity. The calorific value of the melinjo wood samples ranged from 4060-4167 kkal/kg, and the highest calorific value was produced from the side wood which was in line with the high content of lignin and fixed carbon with almost the same volatile matter content. The density and specific gravity of the reaction wood, side wood and opposite wood were almost the same as a result of the small variation in the levels of chemical components in the three wood sections.
Keyword: proximate analysis melinjo, reaction wood, chemical components, physical properties

Judul: Rancang Bangun Sistem Kemudi Otomatis Traktor Pertanian Berbasis Navigasi GPS (Global Positioning System)
Abstrak: Research about the application of automatic navigation system on agricultural tractors has become one of the important research topics in the last two decades especially in the developed countries where the issue of ‘Precision Farming’ application is considered. GPS has been commonly used as the navigation system of vehicles including tractors. The objective of the research was to develop smart tractor that would work automatically based on GPS navigation for cultivation activity in precision farming. Mechatronic navigation control system for agricultural riding tractor including tractor steering, accelerator, clutch, brake system, and hydraulic control had been successfully developed using microcontrollers. GPS interfacing and data processing were also developed using Visual Basic 6.0 and functioned as the main control system. Field test was done on 40 x 20 m area with tractor velocity 0.6 m/s. The average error of control system was 17.9 cm.
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