Judul: Biosensor Asam Urat Menggunakan Urikase dengan Taut Silang Glutaraldehida pada Screen Printed Electrode.
Abstrak: Enzim urikase yang berasal dari Bacillus fastidious dimanfaatkan sebagai pengenal biologis pada biosensor asam urat. Namun, sifat enzim yang mudah terdenaturasi mengakibatkan rendahnya aktivitas, yang dapat ditingkatkan dengan mengimobilisasi enzim dengan glutaraldehida. Screen-printed carbon electrode (SPCE) digunakan sebagai tempat pelekatan menggantikan elektrode kerja pasta karbon (EPK). Respons pengukuran terbaik diperoleh dari SPCE terimobilisasi glutaraldehida yang disimpan pada suhu 4 °C dengan konsentrasi optimum glutaraldehida 1.5% dan konsentrasi asam urat 4 mM. Nilai KM dan Vmaks urikase sebesar 0.8375 mM dan 125 μA. Nilai limit deteksi dan limit kuantisasi pengukuran masing-masing sebesar 0.053 mM dan 0.161 M, dengan sensitivitas 36.987 μA mM–1. Linearitas pengukuran memiliki koefisien determinasi (R2) sebesar 0.9937. Nilai simpangan baku relatif (%SBR) sebesar 1.76%. Stabilitas biosensor asam urat selama 21 hari pengukuran sebesar 85.58%.
Keyword: Bacillus fastidious, biosensor asam urat, glutaraldehida, screen–printed carbon electrode, urikase

Judul: Imobilisasi Urikase Dari Lactobacillus Plantarum Pada Karboksimetilselulose-Gelatin-Zeolit Untuk Meningkatkan Stabilitas Biosensor Asam Urat
Abstrak: Konsentrasi asam urat yang tinggi dalam darah mengindikasikan adanya penyakit. Ada banyak metode yang umum digunakan untuk mengukur kadar asam urat dalam darah, salah satunya adalah biosensor. Penelitian ini bertujuan untuk meningkatkan stabilitas biosensor asam urat dengan cara mengimobilisasi bakteri Lactobacillus plantarum (bioreseptor) pada matriks yang dibuat dari karboksimetilselulosa-gelatin-zeolit. Biosensor asam urat digunakan sebagai alat deteksi awal pasien yang menderita berbagai macam penyakit yang disebabkan oleh tingginya kadar asam urat dalam darah seperti gout, penyakit kardiovaskular, hipertensi, dan lain-lain. Penggunaan sensor ini dalam jangka panjang akan mengurangi performa stabilitasnya, sehingga diperlukan metode untuk meningkatkan stabilitas sensor. Urikase dan matriks didepositkan pada elektroda pasta karbon dan dikarakterisasi menggunakan KCl dan K3Fe(CN)6. Elektroda yang layak digunakan selanjutnya diukur menggunakan voltametrik siklik untuk mengetahui arus yang dihasilkan. Kondisi optimum pengukuran diperoleh dengan memvariasikan konsentrasi asam urat, massa zeolit, dan konsentrasi glutaraldehida. Dari proses optimasi diketahui bahwa kinerja elektroda terbaik adalah pada konsentrasi gltaraldehida 0 mM, massa zeolit 5 gram, dan konsentrasi asam urat 2,3 mM. Parameter kinetik menghasilkan nilai KM dan Vmax berturutturut adalah 478,9 μM dan 9,7266 A. Stabilitas biosensor mencapai 23 hari.
Keyword: biosensor, imobilisasi, zeolit, Lactobacillus plantarum, asam urat, urikase, voltametrik siklik

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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