Ekstraksi Karbon Aktif Bebas Silika dari Arang Sekam Padi untuk Adsorpsi Zat Warna Methyl Orange

Ekstrak karbon aktif bebas silika disintesis dari arang sekam padi berhasil diperoleh dari perbandingan mol karbon : NaOH sebesar 1:3. Hasil SEM pada karbon aktif menunjukkan morfologi materialnya berbentuk butiran dan hasil EDX menunjukkan komposisimya terdiri dari 93,29% karbon, 6,71% oksigen, dan 0% silika. Hasil karakterisasi FTIR karbon aktif bebas silika menunjukkan tidak adanya puncak silika pada bilangan gelombang 1100 cm-1. Berdasarkan hasil karakterisasi SAA, karbon aktif bebas silika memiliki luas permukaan sebesar 6,0018 m2/g, tergolong jenis mikropori. Proses adsorpsi dari karbon aktif bebas silika dalam penyerapan zat warna methyl orange optimum pada massa adsorben sebanyak 200 mg dan maksimum pada massa adsorben 250 mg

Measurement and Simulation Techniques for Piezoresistive Microcantilever Biosensor Applications

Applications of microcantileversas biosensors have been explored by many researchers for the applications in medicine, biological, chemistry, and environmental monitoring. This research discusses a design of measurement method and simuations forpiezoresistivemicrocantileveras a biosensor, which consist of designing Wheatstone bridge circuit as object detector, simulation of resonance frequency shift based on Euler Bernoulli Beam equation, and microcantilever vibration simulation using COMSOL Multiphysics 3.5. The piezoresistivemicrocantilever used here is Seiko Instrument Technology (Japan) product with length of 110 μm, width of 50 μm, and thickness of 1 μm. Microcantilever mass is 12.815 ng, including the mass receptor. The sample object in this research is bacteria EColi. One bacteria mass is assumed to 0.3 pg. Simulation results show that the mass of one bacterium will cause the deflection of 0.03053 nm and resonance frequency value of 118.90 kHz. Moreover, four bacterium will cause the deflection of 0.03054 nm and resonance frequency value of 118.68 kHz. These data indicate that the increasing of the bacteria mass increases the deflection value and reduces the value of resonance frequency

Penurunan Noise Figure Performance (Fn) Pada Hbt Si / Si 1-x Gex Berdasarkan Pengaturan Stripe Emiter Area (Ae) Dan Fraction Mole (X).

Paper ini membahas pengaruh Perubahan stripe emiter area (Ae) dan fraction mole (x) terhadap unjuk kerja HBT SiGe antara lain Resistensi parasitis RB dan RC, fT, fmaks, current gain (β) serta noise figure (Fn,), model dikembangkan dari HBT SiGe IBM generasi kedua dengan Ae 0,1810 m2. Saat Ae diturunkan menjadi Ae 0,1210 m2 dan Ae 0,0910 m2 dan fraction mole (x) dinaikkan menjadi dua kali (2) maka parameter RB, dan β mempunyai relasi positif sedangkan RC , fT, fmaks negatif terhadap Perubahan tersebut. Model HBT SiGe dengan x: 0.1 dan Ae:0,1810 m2 mempunyai nilai Fn minimum terendah dibanding dengan Ae 0,1210 m2 dan 0.0910 m2 yaitu 0.57 dB , 0.64 dB, 0.69 dB. Jika nilai fraction mole (x) diturunkan 50% , menyebabkan kenaikkan Fn yang tidak linier yaitu 77%, 79% dan 89% dari nilai semula. Relasi noise figure (Fn) dengan stripe emiter area (Ae) dan fraction mole (x) diekspresikan dengan relasi berikut ; F k A x n e. 0 , jadi noise figure (Fn) dapat diperkecil dengan memperarea stripe emiter area (Ae) dan menaikkan fraction mole (x). Kata kunci : Noise Figure (Fn), stripe emiter area (Ae), fraction mole (x), SiGe HBT ABSTRAK Paper ini membahas pengaruh Perubahan stripe emiter area (Ae) dan fraction mole (x) terhadap unjuk kerja HBT SiGe antara lain Resistensi parasitis RB dan RC, fT, fmaks, current gain (β) serta noise figure (Fn,), model dikembangkan dari HBT SiGe IBM generasi kedua dengan Ae 0,1810 m2. Saat Ae diturunkan menjadi Ae 0,1210 m2 dan Ae 0,0910 m2 dan fraction mole (x) dinaikkan menjadi dua kali (2) maka parameter RB, dan β mempunyai relasi positif sedangkan RC , fT, fmaks negatif terhadap Perubahan tersebut. Model HBT SiGe dengan x: 0.1 dan Ae:0,1810 m2 mempunyai nilai Fn minimum terendah dibanding dengan Ae 0,1210 m2 dan 0.0910 m2 yaitu 0.57 dB , 0.64 dB, 0.69 dB. Jika nilai fraction mole (x) diturunkan 50% , menyebabkan kenaikkan Fn yang tidak linier yaitu 77%, 79% dan 89% dari nilai semula. Relasi noise figure (Fn) dengan stripe emiter area (Ae) dan fraction mole (x) diekspresikan dengan relasi berikut ; F k A x n e. 0 , jadi noise figure (Fn) dapat diperkecil dengan memperarea stripe emiter area (Ae) dan menaikkan fraction mole (x). Kata kunci : Noise Figure (Fn), stripe emiter area (Ae), fraction mole (x), SiGe HB

Simple: Sistim Penilai Esei Otomatis Untuk Menilai Ujian Dalam Bahasa Indonesia

SIMPLE: System Automatic Essay Assessment for Indonesian Language Subject Examination. Evaluation ofstudy of a student is a very important aspect of an educational process. Evaluation is aimed at measuring the level ofstudent understanding of the given lecture materials. Measuring student understanding of the course material, usingessay-type exam, is generally used as the evaluation tool. In this essay-type exam, the student has to answer questionsusing sentences, whereby choices of possible answers are not indicated. The student has to answer the questions withhis/her sentences. The answers may vary, since it reflects the student's best thoughts of the materials. One of theweaknesses of essay-type exam is the difficulty to grade the answers and it tends to be time consuming. Currently,automatic grading systems that may speed up the grading process, are being developed in many research institutions.The method used to grade, varies form one system to another, and one of the popular system is the Latent SemanticAnalysis (LSA). LSA is a method of grading essay by extracting words and representing the sentence in the form ofmathematical or statistical formulation, from a text with a relatively large number of words. The grade of the essay isdetermined, by matching the important words to a group of words prepared by the human rater. This paper describes aneffort to developed LSA, enhanced with word weighting, word order and the word synonym to improve the accuracy ofgrading. This system is called SIMPLE. SIMPLE is used to grade answers using bahasa Indonesia. The exam is carriedout on-line through the Web. From the experiments conducted, for small classes, the conformity of grade compared tothe grade of human rater lies between 69.80 % - 94.64 %, and for medium size classes the conformity lies between77.18 % - 98.42 % with the human rater. These results are roughly proportional with the result of LSA system, whichgrade essay given in English

Phase Transformation of Rice Husk Ash in the Synthesis of ZSM-5 without Organic Template

Phase transformation of rice husk ash in the synthesis of ZSM-5 without organic template at various crystallization times has been studied. Zeolite has been synthesized using the hydrothermal method at 175 °C with molar ratio 10Na2O : 100SiO2 : 2Al2O3 : 1800H2O with addition of silicalite-1 as seed. Solids were characterized using X-ray diffraction (XRD), infrared (IR) spectroscopy and scanning electron microscopy (SEM) techniques. Analysis of the results of XRD and IR spectroscopy indicated that ZSM-5 crystalstarted to form at 12 h of crystallization time, reaching high crystallinity after 24 h. With a crystallization time of more than 48 h, the ZSM-5 crystals had completely transformed into more stable quartz phase. Results indicated that phase transformation has occurred, in which an amorphous phase of rice husk ash has been transformed to ZSM-5 crystal phase during the early crystallization stage and continued to transform to disordered α-cristobalite phase and lastly quartz phases. SEM showed that the morphology of the ZSM-5 crystal was of an irregular hexagonal shape with particle size distribution around 3-7 μm

Pengaruh Perbandingan Pelarut Etanol dan Dimetilformamida pada Sintesis Metal Organik Framework HKUST-1

Material Metal Organic Framework tipe HKUST-1 dengan rumus molekul [Cu3(BTC)2(H2O)3].xH2O telah disintesis menggunakan prekursor tembaga nitrat trihidrat dan asam 1,3,5 benzenetrikarboksilat melalui metode solvotermal dalam autoklaf dengan variasi volume pelarut etanol dan dimetilformamida pada suhu 100 oC selama 10 jam. Setelah padatan hasil reaksi disaring dan dicuci dengan metanol, diperoleh kristal Cu-BTC berbentuk serbuk berwarna biru cerah. Kristal Cu-BTC dikarakterisasi menggunakan teknik difraksi sinar-X, FT-IR, SEM, Energi Dispersi Sinar-X (EDS) dan TGA. Semua kristal yang didapat memiliki derajat kristalinitas yang tinggi dan menunjukkan kristal berbentuk oktahedral. Cu-BTC yang dihasilkan stabil dengan pemanasan hingga suhu ~350 oC. Keberadaan DMF menyebabkan ukuran kristal Cu-BTC lebih besar sedangkan Pengurangan volume pelarut DMF menyebabkan penurunan massa kristal yang terbentuk dan kurang homoge

PERANCANGAN PEMBANGKITAN FREKUENSI GANDA ANTENA MIKROSTRIP SEGITIGA SAMA SISI MENGGUNAKAN TEKNIK SAMBATAN ELEKTROMAGNETIK

Design of Generating Dual Frequency Operation for Triangular Microstrip Antenna Using ElectromagneticCoupling. A new design is proposed in this paper by applying a pair of slits using a microstrip feed line. Therefore themicrostrip line feeding system is electromagnetically coupled to the patch. The antenna works at two differentfrequencies in the range from 2 GHz to 4 GHz (S band frequency). The results of the simulation shows that the dualfrequency operation can be created when the slit width is 1 mm and the height of the slits ranges from 10 mm to 14 mmwith inter slit distance of 3 mm, 5 mm and 7 mm as well.Keywords: dual frequency, triangular microstrip antenna, microstrip lin