Judul: SEM, EDX, and FTIR Analysis from Salak Pondoh Skin Extracted SiO2
Abstrak: Silikon Dioksida (SiO2) diperoleh dari ektraksi kulit salak pondoh. Kulit salak pondoh dikeringkan terlebih dahulu dengan sinar matahari selama satu hari. Kulit salak pondoh yang telah dikeringkan, dibakar menggunakan oven hingga menjadi abu pada suhu 350oC selama 2 jam. Abu selanjutnya dipanaskan dengan variasi suhu 550oC, 600oC, dan 650oC. Analisis data menggunakan alat SEM (Scanning Electron Microscope) menunjukkan bahwa permukaan SiO2 relatif homogen, analisis EDX (Energy Dispersive X-Ray) menunjukkan bahwa kandungan SiO2 dari kulit salak dalam selang 1% - 20% serta analisis Spektrofotometer FTIR (Fourier Transform Infra Red) menunjukkan bahwa kandungan gugus fungsi dari SiO2 dari kulit salak berupa gugus fungsi O–Si–O pada bilangan gelombang 1167,6 cm-1, gugus fungsi O=Si=O pada bilangan gelombang 1651,3 cm-1, dan gugus fungsi Si–C–Si pada bilangan gelombang 1145,1 cm-1. Hasil analisis yang diperoleh menunjukkan bahwa kulit salak pondoh sangat berpotensial untuk diperoleh Silikon Dioksida., Silicon Dioxide (SiO2) can be obtained from the extraction of the peel of salak pondoh fruit. First, the peel of salak pondoh is dried with the help of sunlight for one day. The peel that has been dried, will be burned to ash using an oven, at 350oC for 2 hours. The ash then is heated further with temperature variations of 550oC, 600oC, and 650oC. Data analysis using SEM (Scanning Electron Microscope) showed that the surface of SiO2 was relatively homogeneous, EDX (Energy Dispersive X-Ray) analysis showed that the content of SiO2 from salak pondoh peel in 1% - 20% interval, and FTIR (Fourier Transform Infra Red) spectrophotometer analysis shows that the functional group content of SiO2 from salak pondoh peel is O–Si–O at wave number 1167.6 cm-1, O=Si=O at wave number 1651.3 cm-1, and Si–C–Si at wave number 1145.1 cm-1. The results of the analysis showed that Silicon Dioxide could be obtained from salak pondoh peel.
Keyword: EDX, FTIR, salak pondoh peel, SEM, silicon dioxide

Judul: Uji Struktur dan Sifat Listrik Silikon Dioksida dan Silikon dari Sekam Padi
Abstrak: Rice husk charcoal is known to contain 93.67% of silicon dioxide and has the potential to produce silicon. This study produced silicon dioxide and silicon, that had been tested for the electrical and structural properties. Incineration process of rice husk charcoal was performed in a furnace at a temperature of 400 oC for 2 hours and 1000 oC for 1 hour, with the increase rate of 5 oC/minute. The incineration yield then washed with HCl 3% (12 ml HCl 3% for 1 grams of rice husk ash), and heated using hotplate and magnetic stirrer, with a speed of 240 rpm for 2 hours at 200 oC. Furthermore sample washed repeatedly using hot distilled water until free of acid, then reheated in a furnace to produce silicon dioxide. Silicon dioxide produced approximately 5.6 to 6.8 grams of 10 grams of rice husk charcoal. The silicon dioxide then mixed with reductor (magnesium powder), using comparisons based on stoikhiometri, afterwards heated in a furnace for 1 hour with a temperature of 650 oC. Based on the results of XRD analysis, the crystallinity of silicon dioxide reaches 75.85 to 83.28% and silicon with value of 53.34%. XRD analysis showed that the silicon dioxide structure is tetragonal with lattice constants a = 12.45 Å and c = 111.77 Å, while the silicon has cube structural with lattice constants a = 5.27 Å. SEM results showed that the silicon dioxide has the smoother surface and the silicon had formed a crystal structure. EDX results for silicon dioxide of about 77.88 to 81.64% and silicon 42.29%. Analysis of electrical properties was performed using the LCR meter and I-V meter, and was known that the silicon dioxide and silicon have the characteristic of semiconductor, where the electrical conductivity of silicon has a value higher than silicon dioxide. The I-V curves showed that silicon dioxide is a diode, while the diode is a resistor.
Keyword: 

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