Judul: Activity and stability of glucose biosensor based on Escherichia coli immobilized on zeolite-glutaraldehyde
Abstrak: Biosensor glukosa berbasis Escherichia coli hingga saat ini telah dikembangkan. Pengembangan ini memiliki beberapa kelemahan, yaitu aktivitas glukosa dehidrogenase (GDH) dan stabilitas elektrode rendah. Penggunaan zeolit pada biosensor dapat meningkatkan aktivitas enzim, sedangkan penggunaan glutaraldehida (GA) sebagai bahan taut-silang dapat meningkatkan stabilitas elektrode. Perancangan percobaan optimisasi dilakukan menggunakan metode permekaan respons (RSM). Kondisi optimum aktivitas biosensor ini ialah suhu 30 oC, pH 6, konsentrasi glukosa 15 mM, konsentrasi pirolokuinolina kuinon (PQQ) 3.5 μM, zeolit 150 mg/mL, dan konsentrasi GA 14.05%. GDH sel E. coli terimobilisasi dapat mendeteksi konsentrasi glukosa hingga 50 mM. Reaksi kinetika GDH sel E. coli terimobilisasi mengikuti persamaan Lineweaver-Burk. Nilai KM app dan Imaks app biosensor ini secara berturut-turut adalah 2.69 mM dan 3.73 μA. Aktivitas GDH sel bakteri relatif stabil sebesar 70–80% selama 4 hari. Oleh karena itu, penggunaan zeolit-GA sebagai matriks imobilisasi dapat meningkatkan aktivitas GDH sel bakteri E. coli yang relatif stabil.
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Judul: Stabilitas dan Efektivitas Biosensor Glukosa Menggunakan Escherichia coli Yang Diimobilisasi Pada Matriks Nanokomposit Zeolit
Abstrak: Biosensor combines the selectivity of biological recognition element and the sensitivity of the transducer. The application of biosensor as blood glucose measurer for diabetes mellitus patients uses purified enzyme as biological sensor. The substitution of purified enzyme with the microbial cells producing enzymes as biological sensor is carried out to overcome the weaknesses of purified enzyme such as the low stability of the enzyme activity and the high cost. This research was carried out to measure the activity of glucose dehydrogenase (GDH)–the enzyme reacting specifically with glucose as substrate and binding with both pyrolloquinoline quinone (PQQ) and Mg2+ ion as prosthetic group and activator respectively-which is exhibited by escherichia coli, using electrochemical methods Design of experiments only to optimalization the activity of GDH bacterial cells of e. coli is a method of surface response. Optimum conditions of activity of GDH derived cells of e. coli bacteria in the absence of a matrix of nanocomposite zeolite on the process of immobilization is the temperature of 30°C, pH 6, concentration of glucose 15 mM, the concentration of PQQ 3,050 μM. As for the optimum conditions for the activity of GDH bacterial cells of e. coli with matrix nanocomposite zeolite is the temperature of 30°C, pH 6, glucose concentration of 15 mM, the concentration of PQQ 3,050 μM, and nanocomposite zeolite 137,50 mg. The reaction catalyzed by GDH kinetics of Glucose Kinetics equation follows the Lineweaver-Burk. The value of KM app bacterial cells of e. coli with the larger of nanocomposite zeolite mM compared to 1,4580 without nanocomposite of zeolite matrix 0,720 mM. This shows that affinity GDH e. coli immobilization of glucose substrate without nanocomposite zeolite is greater compared to the matrix nanocomposite zeolite.GDH activity stability of bacterial cells is not much different compared with no matrix nanocomposite zeolite.
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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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