Pembuatan Lapisan Tipis Oksida Grafena Tereduksi sebagai Material Elektroda Sistem Kapasitor dan Karakterisasinya

Grafena adalah material karbon dua dimensi dan memiliki sifat mekanik, listrik, dan termal yang unggul. Grafena memiliki potensi sebagai bahan elektroda sistem penyimpanan energy seperti superkapasitor. Dalampenelitian digunakan bahan reduced graphene oxide (RGO) yang diperoleh melalui proses reduksi secara termal bahan graphene oxide (GO) komersial. Lapisan tipis GO di atas substrat ITO-glass dibuat menggunakan metode Spincoating pada kecepatan 1000 rpm selama 60 sekon. Lapisan tipis RGO diperoleh dengan cara pemanasan lapisan tipis GO pada temperatur 200C selama 1 jam. Sistem kapasitor menggunakan anoda dan katoda dari bahan RGO di atas dan untuk medium elektrolit digunakan larutan H2SO4 1 Molar. Karakteristik sistem kapasitor tersebut diamati melalui pengukuran cyclic voltammetry (CV) secara potensio-static pada rentang tegangan -0,2-0,8 volt dengan scan rate 125 mV/s. Juga dilakukan karakteristik charge-discharge melalui pengukuran pengisian-pengosongan muatan secara galvano-static. Karakteristik sifat penyimpanan muatan secara kapasitip diperlihatkan dengan adanya pola histerisis pada hasil kurva CV. Hasil pengukuran charge-discharge memperlihatkan pola kurva segitiga yang mengindikasikan adanya proses penyimpanan muatan. Nilai kapasitansi spesifik maksimum elektroda RGO adalah 1,54 × 10−4/massa F/g pada kondisi arus pengosongan 0,7 μA.ABSTRACTGraphene is a two-dimensional carbon material and has superior mechanical, electrical, and thermal properties. Graphene has potential as an electrode material for energy storage systems such as supercapacitors. In the study used reduced graphene oxide (RGO) material obtained through the thermal reduction process of commercial graphene oxide (GO) material. The GO thin layer on the ITO-glass substrate was made using Spin coating method at 1000 rpm for 60 seconds. The RGO thin layer was obtained by heating the GO thin film at a temperature of 200C for 1 hour. The capacitor system uses the anode and cathode of the above RGO material and for the electrolyte medium, a 1 Molar H2SO4 solution is used. The characteristic of the capacitor system was observed by potential-static cyclic voltammetry (CV) measurements in the voltage range of -0.2-0.8 volts with a scan rate of 125 mV/s. Also performed the characteristics of charge-discharge through the measurement of charge-discharging charge in galvanostatic. Characteristic properties of energy storage are shown in the presence of a pattern of hysteresis on the CV curve. The result of the charge-discharge measurement shows a triangle curve pattern indicating the existence of a storage process of the charge. The maximum specific capacitance value of RGO electrode is 1.54 × 10−4 / mass F/g at 0.7 μA discharge current condition

Bionatura : Vol. 8, No. 1, Maret 2006

1. Analisis urutan Nukleotida Daerah Hipervariabel I (HVI) DNA Mitokondria pada Suku Baduy untuk Menentukan Motif Populasi Suku Sunda / Iman P. Maksum, Dian S. Kamara, Teni W. Hartati 2. Penghentian Pendedahan HanPV tehadap Helicoverpa armigera Hubner / Yayan Sanjaya, et al. 3. Penhambatan Enkapsulasi Pradewasa Parasitoid Eriborus argenteopilosus (CAMERON) oleh Larva Crocidolomia pavonana (F.) Menggunakan Rokaglamida / Danar Dono, et al. 4. Uji Kemankusan Moluskosida Keong Mas (Pomacea canaliculata) di Laboratorium dan Lapangan / Musri Musman 5. Elevated Alumunium Concentrations in Soil Reduce Growth and Function of External Hyphae of Gigaspora Margarita in Growth of Cowpea Plants / Agus Rohyadi 6. Efek Sifat Fisik Terhadap Permeabilitas dan Suction Head Tanah (kajian empirik untuk meningkatkan laju infiltrasi) / Indratmo Soekarno, Dede Rohmat 7. Budidaya Kuda Laut (Hyppocampus barbourie): upaya perbenihan di laboratorium dan penangkaran dalam karamba apung / A Niartiningsih, Irfan Ambas, Syafiuddin 8. Efektifitas Penggunaan Ulang Mulsa Plastik Hitam Perak dengan Pemberian Pupuk Nitrogen terhadap Pertumbuhan dan Hasil Cabai / Fahrurozi, Nanik Setyowati, Sarjon

EXPRESSION OF RECOMBINANT ANTIBODY FRAGMENT, ANTI BNP-SCFV ON THE PERIPLASM OF Escherichia coli FOR THE DETECTION OF HEART FAILURE

Basic natriuretic peptide (BNP) is a polypeptide hormone consist of 32 amino acids that secreted by the heart ventricle to respond the excessive stretching of heart muscle cells. BNP can be used as prognostic marker for patients with heart failure. The presence of BNP in blood can be detected by BNP antibody, which is anti BNP-single chain variable fragment (Anti BNP-SCFV). The antibody is a combination of polypeptides between varying region on the heavy chain (VH) and the light chain (VL) of immunoglobulin. Anti BNP-SCFV will bind to BNP through the antigen-antibody interaction. Concentration of BNP in a patient’s blood can be detected through the interaction of BNP with Anti BNP-SCFV using immunosensor method. Production of recombinant Anti BNP-SCFV in Escherichia coli as host is reported in the present study. Anti BNP-SCFV was expressed in fusion form with OmpC signal peptide that direct the protein to a periplasmic space. Expression was performed under RhaBad promoter as control using L-rhamnose as inducer. SDS-PAGE characterization showed consistent band at 28 kDa, which was assumed as Anti BNP-SCFV. The optimum expression was found at four hours after induction with 4 mM inducer. Anti BNP-SCFV was secreted from the cell as characterized by the presence of the protein on periplasmic membrane and extracellular fraction

Study of the Interaction Carbondioxide Gas with Hydroxyapatite Using Density Functional Theory

Hydroxyapatite (HA) is a phosphate mineral with Ca10(PO4)6(OH)2 chemical formula. The hydroxyl group in HA allows ion to exchange, so this material may be applied as a CO2 gas sensor. The interaction between HA with CO2 gas is difficult to observe directly, and ab initio modeling is necessarily to investigate the interactions between HA with CO2 gas. In this study, a simulation was conducted using the density functional theory method to determine the interaction between CO2 gas on the surface of HA. The simulation results indicate that a large HA surface is required for optimal CO2 gas adsorption. Pore diameter size needs to be larger than 2.5 Å to prevent binding on two sides of the surface pores

Hartati Proceeding of The International Seminar on Chemistry

Abstract DNA biosensors based on DNA hybridization play a more important role in DNA analysis. This report describes the electrochemical DNA hybridization sensors for sequences recognition on graphite/carbon paste and disposable pencil graphite electrodes. The immobilization technique is adsorption on the electrode surface. The formation of double-stranded DNA upon hybridization are detected using a redoks-active intercalator, and label free, in connection with differential pulse voltammetry measurements. Factors influencing the performance of these biosensors are investigated. The low detection limits (e.g., 36 ng ml -1 S. typhi DNA and 2.35 % heteroplasmy DNA mutation) are coupled to a good surface-to-surface reproducibility (RSD of 7.4 % referred to carbon paste electrodes and 8.4 % to disposable pencil graphite electrodes for triplicate measurements). These and similar developments are expected to have a profound effect on diagnostic, food, and environmental analysis