Judul: Aktivitas Antimikroba Nanopartikel Perak yang Disintesis Menggunakan Ekstrak Kulit Jeruk Purut
Abstrak: Jeruk purut telah dikenal luas oleh masyarakat Indonesia. Namun sejauh ini belum banyak masyarakat yang mampu memanfaatkan limbah kulit jeruk purut, khususnya limbah di pasar dan di rumah yang dapat menambah nilai guna dan tentunya nilai jualnya. Jeruk purut kaya manfaat terutama kulit buah dan daunnya sebagai agen antibakteri yang dapat mutakhir membunuh kuman. Berdasarkan hal tersebut penelitian ini menggunakan limbah kulit jeruk purut yang dapat dimanfaatkan sebagai bioreduktor dalam sintesis nanopartikel perak menggunakan metode green synthesis untuk menguji sifat antibakterinya. Di sisi lain, penggunaan reagen kimia dalam proses sintesis nanopartikel perak dapat berdampak terhadap lingkungan serta membutuhkan biaya pengeluaran yang tinggi. Oleh sebab itu dalam penelitian ini dilakukan metode alternatif yang lebih murah dan ramah lingkungan yang tidak berdampak pada lingkungan. Justru membantu mengurangi limbah rumah tangga. Hasil kemampuan antibakteri menunjukan bahwa nanopartikel yang telah disintesis dengan konsentrasi 1 mM dan 1,5 mM ditemukan efektif membunuh pertumbuhan spesies bakteri Stapylococcus aureus., Kaffir lime has been widely known by the people of Indonesia. However, so far not many people have been able to utilize the waste of kaffir lime peels. Kaffir lime is rich in benefits, especially the skin of the fruit and leaves as an antibacterial agent that can kill germs. Based on this, this research uses kaffir lime peel waste which can be used as a bioreductant in the synthesis of silver nanoparticles using the green synthesis method to test its antibacterial properties. On the other hand, the use of chemical reagents in the synthesis of silver nanoparticles can have an impact on the environment and require high costs. Therefore, in this study an alternative method that is cheaper and environmentally friendly has no impact on the environment. It actually helps reduce household waste. The results of the antibacterial ability showed that the nanoparticles that had been synthesized with a concentration of 1 mM dan 1,5 mM were found to be effective against the species of bacteria Stapylococcus Aureus.
Keyword: antimicrobial test, green synthesis, kaffir lime, nanoparticles

Judul: Silver Nanoparticle Biosynthesis Using Kaffir Lime  Peel Waste (Citrus hystrix) with Bioreductor Volume Variations
Abstrak: Jeruk purut (Citrus hystrix) merupakan tanaman yang telah dikenal masyarakat yang memiliki banyak kegunaan. Kandungan dalam kulit jeruk purut berpotensi dijadikan bahan bioreduktor dalam sintesis nanopartikel. Nanopartikel perak sebagai salah satu jenis nanopartikel logam memiliki sifat antibakteri serta proses sintesisnya sudah banyak dilakukan. Sintesis nanopartikel perak dilakukan dengan mereaksikan ekstrak kulit jeruk purut sebagai bioreduktor dan AgNO3 dengan konsentrasi 1 mM untuk meninjau kondisi optimal pengaruh volume bioreduktor dan suhu terhadap biosintesis nanopartikel perak. Rancangan percobaan dibuat menggunakan Response Surface Methodology dengan bentuk Central Composite Design (CCD). Nilai absorbansi maksimum 0.41-2.52 yang tercapai pada panjang gelombang 267-289 nm. Ukuran partikel yang diperoleh berkisar pada 84-503 nm yang masih dalam ukuran toleransi nanopartikel. Hasil penelitian ini menunjukkan bahwa nanopartikel perak berdiameter kurang dari 100 nm tercapai pada variasi volume 1.5 ml dengan suhu 70⁰C., Kaffir lime (Citrus hystrix) is a plant that has been known to the public that has many uses. The content in kaffir lime peel has the potential to be used as a bioreductant in the synthesis of nanoparticles. Silver nanoparticles as a type of metal nanoparticles have antibacterial properties and many synthesis processes have been carried out. The synthesis of silver nanoparticles was carried out by reacting kaffir lime peel extract as a bioreductant and AgNO3 with a concentration of 1 mM to examine the optimal conditions for the effect of bioreductant volume and temperature on the biosynthesis of silver nanoparticles. The experimental design was made using Response Surface Methodology in the form of Central Composite Design (CCD). The maximum absorbance value is 0.41-2.52 which is achieved at a wavelength of 267-289 nm. The particle size obtained is in the range of 84-503 nm which is still within the tolerance of nanoparticles. The results of this study indicate that silver nanoparticles with a diameter of less than 100 nm are achieved at a volume variation of 1.5 ml at a temperature of 70⁰C.
Keyword: AgNO3, biosynthesis, Citrus hystrix, RSM, silver nanoparticles

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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