Judul: Synthesis of Ulvan-based Hydrogel from Ulva lactuca Seaweed as Probiotic Immobilization Scaffold
Abstrak: Hidrogel berbasis polisakarida bersulfat ulvan terbuat dengan tambahan polimer pendukung yaitu matriks alginat. Sintesis hidrogel berbasis ulvan-alginat sebagai scaffold untuk imobilisasi probiotik belum pernah dilaporkan. Ulvan merupakan polisakarida bersulfat yang berasal dari rumput laut hijau Ulva. Ulvan diperoleh dari ekstraksi rumput laut Ulva lactuca yang umumnya dilakukan dengan suhu tinggi dan waktu yang lama sehingga diperlukan metode alternatif dalam proses ekstraksinya untuk menghasilkan ulvan dengan kualitas baik namun efisien dalam prosesnya. Alternatif proses ekstraksi yang bisa dilakukan yaitu penggunaan ultrasonikasi yang dapat mengurangi penggunaan pelarut organik dan energi yang tinggi. Penelitian bertujuan mengkarakterisasi Ulva lactuca, menentukan pengaruh Ultrasound-assisted Extraction (UAE) terhadap mutu ulvan, dan menentukan formulasi hidrogel terbaik berbasis ulvan untuk imobilisasi probiotik. Tahapan penelitian meliputi preparasi sampel, optimasi ekstraksi ulvan, dan sintesis hidrogel dengan variasi ulvan (0, 1, 2, 3, dan 4 %)) dan konsentrasi tetap alginat 4%. Ulvan terpilih berdasarkan kandungan sulfat terbesar yaitu 57,20 ± 0,11 % hasil ekstraksi dengan NaOH berbantu ultrasonikasi. Hidrogel ulvan-alginat menghasilkan fraksi gel dan rasio swelling terbaik sebesar 31,88 ± 3,80 % dan 57,18 ± 19,88 % dengan total bakteri probiotik sebesar 8,5 ± 4,9 × 106 log CFU/g. Ulvan dapat berperan sebagai bahan makanan pada hidrogel scaffold sehingga mampu mempertahankan keberadaan bakteri probiotik.
Keyword: imobilisasi probiotik, hidrogel, Ulva lactuca, ulvan

Judul: Synthesis and Characterization of Ulvan Alginate Hydrogel Beads with Encapsulated Probiotics.
Abstrak: Minuman probiotik memiliki berbagai keuntungan bagi saluran pencernaan. Namun, terdapat masalah pada kepastian kelangsungan hidup probiotik dan fungsionalitasnya selama melalui saluran pencernaan hingga mencapai usus besar, sehingga diperlukan metode alternatif untuk mempertahankan kelangsungan hidup probiotik yaitu enkapsulasi hydrogel beads dari biopolimer alami yaitu alginat dan ulvan. Hydrogel beads yang dikonstruksi dari alginat dan ulvan diprediksi akan sesuai dengan tantangan sebagai bioreaktor probiotik yang dapat menstimulasi kesehatan pencernaan manusia karena secara kimia dapat dikontrol porositas dan kapasitas retensinya. Pengaplikasian hydrogel beads dalam penelitian ini dilakukan pada minuman tisane sargassum. Penelitian bertujuan menentukan karakteristik konsentrasi ulvan terpilih, ketahanan bakteri probiotik terenkapsulasi dalam simulated gastric fluid (SGF) dan simulated intestinal fluid (SIF) serta karakteristik hydrogel beads di dalam minuman tisane sargassum. Tahapan penelitian terdiri dari karakterisasi hydrogel beads dengan konsentrasi ulvan (1%, 2%, 3%, dan 4%) dan alginat 2% serta pengaplikasian hydrogel beads pada tisane sargassum. Hydrogel beads ulvan alginat menghasilkan fraksi gel dan rasio swelling tertinggi sebesar 98,8% dan 19,7%. Hydrogel beads dapat mempertahankan tingkat kelangsungan hidup bakteri probiotik pada kedua kondisi yaitu SGF dan SIF sebesar 3,41×10^7 log CFU/g dan 0,14×10^7 log CFU/g. Hasil analisis sensori menghasilkan formulasi terpilih dengan perlakuan ukuran hydrogel beads R2 (sedang) dengan ukuran 9,05 ±0,92 mm, hal ini menunjukkan bahwa ukuran hydrogel beads memengaruhi tingkat kesukaan panelis., Probiotic beverages offer a range of advantages for the digestive system. However, issues arise concerning the viability and functionality of probiotics as they traverse the digestive tract to reach the large intestine. As a result, alternative methods are required to sustain probiotic viability, such as encapsulating them in hydrogel beads made from natural biopolymers like alginate and ulvan. The construction of hydrogel beads from alginate and ulvan is predicted to address challenges as a probiotic bioreactor that can promote human digestive health, primarily due to the controllable chemical properties of porosity and retention capacity. In this study, hydrogel beads were applied within the context of sargassum tisane, a beverage. The research aimed to determine the characteristics of the selected ulvan concentrations, the resilience of encapsulated probiotic bacteria within simulated gastric fluid (SGF) and simulated intestinal fluid (SIF), and the attributes of hydrogel beads within sargassum tisane. The research phases encompassed the characterization of hydrogel beads with varying ulvan concentrations (1%, 2%, 3%, and 4%) and a constant 2% alginate concentration. Subsequently, the hydrogel beads were introduced into the sargassum tisane. The hydrogel beads composed of ulvan and alginate yielded the highest gel fraction and swelling ratio at 98.8% and 19.7%, respectively. These hydrogel beads effectively maintained the survival levels of probiotic bacteria under both SGF and SIF conditions, registering at 3.41×10^7 log CFU/g and 0.14×10^7 log CFU/g, respectively. Sensory analysis results identified a preferred formulation, indicating that the size of hydrogel beads, specifically the R2 (medium) size at 9.05 ± 0.92 mm, significantly influenced the panelists' preference levels. This underscores the impact of hydrogel bead size on palatability perception.
Keyword: alginate, bacterial probiotic, hydrogel beads, ulvan

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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