Judul: Purifikasi parsial B-Galaktosidase Enterobacter cloacae dan penentuan karakternya pada kondisi Teramobil dengan Na-Alginat
Abstrak: Enzim ẞ-galaktosidase (EC 3.2.1.23) merupakan enzim yang dapat menghidrolisis laktosa menjadi glukosa dan galaktosa. Pada penelitian ini, purifikasi parsial B-galaktosidase dilakukan dengan metode pengendapan diikuti dengan dialisis, sementara amobilisasinya dilakukan menggunakan Na-alginat. Tujuan penelitian ini adalah melakukan purifikasi parsial ẞ-galaktosidase dari Enterobacter cloacae dan karakterisasi {pH optimum, suhu optimum, parameter kinetika (Vmaks dan KM)} pada kondisi teramobilisasi dengan Na-alginat. Aktivitas spesifik ẞ- galaktosidase pada ekstrak kasar, pengendapan amonium sulfat 40%, dan dialisis masing-masing sebesar 2.167 U/mg, 5.297 U/mg, dan 12.586 U/mg dengan faktor pemurnian masing-masing sebesar 1,000; 2,445 dan 5,809. Kondisi optimum ẞ- galaktosidase E. cloacae purifikasi parsial yang teramobilisasi adalah pada suhu 40°C dengan aktivitas sebesar 0.012 U/mL dan pada pH 7 dengan aktivitas sebesar 0.009 U/mL, sedangkan parameter kinetikanya adalah Vmaks sebesar 1.273 µmol/menit dan nilai KM sebesar 1.961 mM.
Keyword: Purifikasi, B-Galaktosidase, Amobilisasi

Judul: Purifikasi, amobilisasi, dan karakterisasi β-galaktosidase dari Enterobacter cloacae serta potensinya terhadap susu UHT
Abstrak: Enzymatic hydrolysis of lactose is an important biotechnological process because the hydrolyzed products can be consumed by people with lactose intolerance. The aim of this study was purification, immobilization, and characterization of β-galactosidase from E. cloacae. This research also studied the hydrolysis of lactose in UHT milk. The stages of this research were production and purification β-galactosidase from E. cloacae; characterization of enzyme; optimization of immobilization formula; and hydrolisis of UHT milk. The β- galactosidase from E. cloacae was purified and showed a purification of 30.26- fold, a yield of about 6.18%, and a specific activity of 101.781 U/mg. Free and immobilized enzyme exhibited maximum activity at an optimal pH of 7.0 and an optimum temperature of 40°C. This enzyme was activated by Co2+, Mn2+, and Mg2+; however, was inhibited by Ca2+, Zn2+, Cu2+, and Hg2+. KM for free and immobilized β-galactosidase were 0.434 and 2.068 mM, respectively. Optimal formulation of cell and enzyme immobilization were consist of 10% (w/v) cell with 5% (w/v) sodium alginate and 10% (v/v) purified enzyme with 5% (w/v) sodium alginate, respectively. This researh found that entrapped β-galactosidase was higher in the hydrolysis of lactose present in milk (28.09%) after 6 hours in batch process as compared to entrapped E. cloacae (22.01%) after 18 hours. Free β-galactosidase was higher in the hydrolysis of lactose present in milk (78.20%) after 6 hours as compared to free E. cloacae (55.14%) after 18 hours.
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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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