Judul: Pemanfaatan Kembali dan Modifikasi Elekrode Screen Printed Carbon Bekas dan Aplikasinya untuk Mendeteksi Asam Galat
Abstrak: Penelitian ini memodifikasi elektrode kerja screen printed carbon electrode (SPCE) bekas dengan campuran grafit:polistirena dan mengaplikasikannya untuk deteksi asam galat dengan metode voltammetri. Komposisi grafit:polistirena diragamkan pada nisbah 95:5, 90:10, dan 85:15. SPCE yang telah dimodifikasi (rSPCE) dievaluasi kinerjanya menggunakan K3Fe(CN)6.. Selanjutnya rSPCE digunakan untuk deteksi asam galat. Kondisi optimum pengukuran asam galat diperoleh pada saat digunakan bufer fosfat pH 2.5 sebagai elektrolit dan elektrode dibilas pada setiap ulangan pengukuran. Deteksi asam galat menghasilkan 2 puncak oksidasi masing-masing pada potensial 0.26 V dan 0.63 V vs Ag/AgCl. Elektrode dengan komposisi grafit:polistirena 95:5 memberikan respon terbaik pada pengukuran asam galat. Konsentrasi asam galat dan intensitas puncak oksidasinya menunjukkan hubungan yang linear dengan koefisien determinasi R2 = 0.9947 untuk puncak 1 dan R2 = 0.9864 untuk puncak 2. Presisi pengukuran asam galat dengan rSPCE 95:5 cukup baik dengan %SBR kurang dari 5%.
Keyword: asam galat, grafit, polistirena, SPCE

Judul: Deteksi Glutation Menggunakan Screen Printed Carbon Electrode Termodifikasi Grafena
Abstrak: Glutation merupakan senyawa penanda stres oksidatif, yaitu keadaan saat jumlah radikal bebas di dalam tubuh lebih banyak dibandingkan antioksidannya. Pada penelitian ini deteksi glutation dilakukan dengan screen printed carbon electrode (SPCE) dan SPCE termodifikasi grafena (SPCE-Gr). Grafena disintesis menggunakan bantuan gelombang mikro dengan ion nitronium sebagai pereaksi. Permukaan SPCE dimodifikasi dengan grafena melalui metode elektrodeposisi. Pada pengukuran langsung dalam elektrolit bufer fosfat, puncak oksidasi glutation terdeteksi pada potensial 0.65 V (vs Ag/AgCl). Pengukuran glutation dalam larutan bufer fosfat menggunakan SPCE-Gr menghasilkan limit deteksi 3.99 μM dan presisi dinyatakan sebagai persen simpangan baku relatif (%SBR) sebesar 1.71%. Disamping itu, glutation dapat diukur secara tidak langsung dengan memanfaatkan reaksi redoks bromida sehingga didapatkan limit deteksi sebesar 6.41 μM dan 8.10 μM masing-masing untuk SPCE dan SPCE-Gr. Presisi pengukuran glutation secara tidak langsung menggunakan SPCE dan SPCE-Gr cukup baik dengan %SBR berturut-turut sebesar 3.44% dan 2.95%. Hal ini menunjukkan bahwa SPCE termodifikasi grafena cukup potensial untuk pengukuran glutation secara elektrokimia.
Keyword: glutation, grafena, screen printed carbon electrode, voltametri 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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