Judul: Material Nanotabung Imogolit dan Interaksinya dengan Ekstrak Herbal Indonesia.
Abstrak: Obat bahan alam dapat dibuat dari berbagai ekstrak herbal, seperti tabat barito (Ficus deltoidea) dan jambu biji (Psidium guajava). Ekstrak air, etanol 30%, dan etanol 96% daun tabat barito dan jambu biji memiliki kelarutan yang rendah dalam sejumlah pelarut. Imogolit dipilih sebagai material alternatif untuk meningkatkan dispersi ekstrak dalam larutan meskipun informasi tentang interaksinya dengan ekstrak herbal belum banyak diketahui. Pada kondisi normal, imogolit hanya berubah menjadi gel ketika dilarutkan dalam etanol 96% dengan penggembungan 16.33%. Pada pH 10, imogolit membentuk gel dalam semua pelarut terpilih dengan penggembungan 25.14%. Imogolit dalam larutan ekstrak herbal dapat meningkatkan dispersi ekstrak dalam larutan dan berubah menjadi gel dengan penggembungan terbesar 29.22% yang tidak terpengaruh oleh kenaikan pH. Nilai penggembungan imogolit dalam larutan filtrat maserasi menunjukkan hasil yang lebih baik dari larutan ekstrak dengan penggembungan 56.78%.
Keyword: Ficus deltoidea, herbal, imogolit, penggembungan, Psidium guajava

Judul: Literature Review of Synthesis Method, Modification, and Application of Imogolite
Abstrak: Imogolit adalah mineral alumina silika dengan struktur nanotabung berdinding tunggal. Imogolit memiliki rumus molekul (OH)3Al2O3Si(OH) yang tersusun dari lapisan oktahedron melengkung Al(OH)3 pada bagian luar; dan gugus Si(OH)3 pada bagian dalam. Imogolit dapat diperoleh dari alam maupun sintesis dari prekursor Si dan Al. Beberapa rute sintesis dapat mengontrol struktur dan sifat kimia imogolit, sehingga memungkinkan adanya modifikasi pada rongga dalam maupun permukaan luarnya. Modifikasi ini menjadi potensi besar dalam berbagai aplikasi imogolit. Penelitian ini bertujuan meninjau berbagai tulisan mengenai metode sintesis, modifikasi, dan aplikasi imogolit. Metode peninjauan berupa studi literatur dengan cara mengumpulkan data yang berhubungan dengan topik melalui pendekatan systematic literature review. Hasil penelusuran memaparkan bahwa imogolit dapat diperolah dari alam dengan proses pemurnian batuan atau disintesis melalui proses hidrolisis prekursor Si dan Al dengan NaOH hingga nsibah OH/Al= 2, lalu dipanaskan, dan dipurifikasi. Struktur imogolit dapat dimodifikasi melalui proses kondensasi prekursor maupun mengkompositkan imogolit dengan material lain. Hasil modifikasi menunjukkan potensi imogolit di bidang polimer, terutama untuk penguatan polimer dengan cara mengompositkan imogolit dengan senyawa organik secara in situ. Imogolit termodifikasi juga dapat digunakan sebagai katalis. Di bidang kesehatan, nanokomposit imogolit digunakan sebagai agen pembawa obat, templat untuk enzim, imobilisasi DNA, dan sebagai agen antibakteri., Imogolite is an alumino-silicate mineral with a single-walled nanotube structure. The molecular formula of imogolite is (OH)3Al2O3Si(OH) which composed by curved octahedral layer Al(OH)3 on the outside and Si(OH)3 group on the inside. Imogolite can be obtained from nature or synthetically from Si and Al precursors. Several synthetic routes can control the structure and properties of the imogolite, thereby allowing modification in the inner and outer surface. This modification has good potential in various imogolite applications. This study aims to review various writings on the synthesis, modification process, and application of imogolite. The method is a literature study by collecting data related to the topic through a systematic literature review approach. The study showed that imogolite results from nature by refining rocks or synthesized through the hydrolysis of Si and Al precursors with NaOH until the OH/Al ratio = 2, heated, and purified. The modified imogolite structure resulted from the precursor condensation or by compositing with other materials. The modification results showed the potential application of imogolite in the polymer field, especially for polymer reinforcement by in situ composites of imogolite with organic compounds. Modified imogolite is also for catalyst utilization. Application imogolite nanocomposites in the medical field are as drug delivery agents, templates for enzymes, immobilization of DNA, and antibacterial agents.
Keyword: imogolit, imogolit termodifikasi, sintesis imogolit

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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