Judul: Hubungan Kekuatan Antioksidan Ekstrak Teh, dan Air Gambut terhadap Ukuran Nanoperak dan Aktivitas Antibakteri
Abstrak: Nanoperak merupakan salah satu nanomaterial yang telah banyak diteliti karena memiliki aplikasi yang luas. Sintesis nanoperak telah berkembang, salah satunya adalah dengan menggunakan reduktor alami sehingga tidak berbahaya bagi manusia dan lingkungan. Urutan kekuatan antioksidan metode 1,1-difenil-2- pikrilhidrazil (DPPH) maupun kekuatan reduksi mulai dari tertinggi sampai terendah adalah teh, kopi, lalu air gambut. Karakteristik puncak serapan UV-Vis nanoperak menggunakan ketiga reduktor berbanding lurus dengan kekuatan antioksidannya. Ukuran nanoperak semakin kecil dengan bertambahnya kekuatan antioksidan. Semakin kecil ukuran nanoperak, aktivitas antibakterinya akan semakin besar. Urutan aktivitas antibakteri tertinggi sampai terendah ialah nanoperak-teh, nanoperak-kopi, diikuti oleh nanoperak-air gambut.
Keyword: antibakteri, antioksidan, nanoperak, puncak serapan

Judul: Sintesis, Karakterisasi, dan Analisis Aktivitas Antimikroba Nanopartikel Perak Menggunakan Ekstrak Teh Hitam (Camellia sinensis).
Abstrak: Nanopartikel perak sangat diminati dalam berbagai terutama dalam bidang optis, katalisis, dan biomedis bidang karena memiliki sifat fisika, kimia, dan antimikroba yang unik. Sintesis nanopartikel perak menggunakan reduktor alami dari tumbuhan merupakan metode yang ramah lingkungan (ecofriendly). Penelitian sebelumnya menyatakan perak dengan ekstrak daun Abutilon indicum menghasilkan ukuran nanopartikel 7-17 nm dan efektif sebagai antimikroba terhadap bakteri Gram positif B. Substilus dan Gram negatif E. coli. Berdasarkan penelitian sebelumnya, maka dilakukan penelitian yang bertujuan untuk sintesis dan formulasi nanopartikel perak dengan menggunakan ekstrak teh hitam (Camellia sinensis), karakterisasi dan analisis aktivitas antimikroba terhadap jamur Fusarium oxysporum dan bakteri Ralstonia solanacearum. Sintesis dilakukan dengan pencampuran AgNO3 10 mM dan ekstrak daun teh hitam dengan perbandingan 90:10, kemudian inkubasi selama 24 jam. Berdasarkan analisis PSA, nanopartikel perak yang terbentuk memiliki ukuran rerata 174 nm dan hasil analisis FTIR menunjukan adanya gugus polifenol dan polisakarida. Nanopartikel perak efektif sebagai antifungal Fusarium oxysporum hingga 59.7 % (500 ppm) dan antibakteri Ralstonia solanacearum sebesar 99% (12,5 ppm).
Keyword: Antimikroba, Nanopartikel, Perak, Sintesis

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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