Judul: Identification and optimization of growth media of microalgae originated from Cipanas hot spring water West Java that is potential for biodiesel source
Abstrak: The increasing use of fossil fuel leads to the depletion of fuel sources and increases CO2 emission level into the environment that affects global warming. Microalgae is an alternative biodiesel source that is renewable and environmentally friendly. The objective of the research was to identify and optimize the growth media of microalgae isolate originated from Cipanas hot spring water. Identification was done based on morphological and 18S rDNA gene sequence approaches. Growth media experiment was designed as a factorial randomized block design. First factor was water media composition containing aquades and hot spring water with five level of aquades:hot spring water ratio, which were 1:0, 0:1, 1:1, 2:1, and 1:2 (v/v). The second factor was P concentration, which were 40, 80 and 120 ppm. The result showed that the morphologically a microalgae isolate had similarity to Chroococcus sp prokaryotic, but molecular data indicated that the microalgae was similar to uncultured freshwater eukaryote clones. The highest cell density of microalgae culture was 2.19 and 2,21 which were achieved when microalgae was cultured in aquades:hot spring water medium 1:2 (v/v) and in P concentration 120 ppm, respectively. The highest dry weight average of biomass (175 mg) was obtained in aquades:hot spring water 1:0 (v/v) with P concentration 120 ppm. Hot spring water could be substituted by aquades to gain high lipid content microalgae. Growth media containing aquades:hot spring water 1:0 (v/v) with P concentration 40 ppm produced the highest average of lipid content (21%) and highest average of lipid productivity, 17 mg l-1 day-1.
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Judul: Optimasi lingkungan tumbuh mikroalga dari kawah ratu Sukabumi yang berpotensi sebagai sumber biodiesel
Abstrak: Microalgae is a potential as a source for biodiesel and can be cultured in a large scale. The objective of this study was to optimize growing environment (nitrogen consentration in media and light intensity) for microalgae from Kawah Ratu Sukabumi. Microalgae that was previously isolated and cultured, identified and examined for the lipid content using Nile Red method. Microalgae was then grown in the media with different concentrations of nitrogen (0, 0.5, 1 and 2 M) and light intensities (105, 140, 70, 175 mmol photon/m2 / s) over 16 days. Lipid content is monitored at 16 day after inoculation. Based on lipid content, only Chlorella sp. from Kawah Ratu that was potential as a raw material for biodiesel. Chlorella sp. grew the best in media BG11 containing of 750 ppm nitrogen under 70 μmol foton/m2/s light intensity. The highest lipid productivity was produced (10.8 mg/l/day) when it was grown on media BG11 under 70 μmol foton/m2/s light intensity.
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Judul: Monotonicity Properties of Trapezoid Sum Sequence on Class of Nonconvex and Nonconcave Function
Abstrak: Bernhard Riemann mendefinisikan integral tentu sebagai luas daerah di bawah kurva dari suatu fungsi real taknegatif pada sebuah interval yang tertutup dan terbatas. Beberapa alternatif yang dapat digunakan untuk menghampiri luas tersebut adalah Darboux sums melalui penjumlahan beberapa luas persegi panjang dan trapezoid sum melalui penjumlahan luas trapesium. Trapezoid sum lebih baik dalam menghampiri nilai integral untuk fungsi-fungsi yang well-behaved daripada Darboux sums. Untuk fungsi f yang bernilai real dan kontinu pada interval [a,b], f terintegral Riemann jika dan hanya jika f terintegral Darboux. Pada tesis ini ditunjukkan bahwa f terintegral Riemann jika dan hanya jika f terintegral secara trapesium. Misalkan f adalah suatu fungsi bernilai real yang kontinu pada interval [a,b]. Untuk setiap partisi P_n yang membagi [a,b] menjadi n subinterval dengan jarak yang sama, dibentuk trapezoid sum T_n (f) yang merupakan jumlah luas n trapesium sebagai pendekatan dari nilai integral f pada [a,b]. Jika f adalah fungsi konveks maka barisan trapezoid sum {T_n (f)} bersifat monoton turun dan akan bersifat monoton naik jika f fungsi konkaf. Fokus tesis ini adalah sifat kemonotonan barisan {T_n (f)} untuk fungsi f yang nonkonkaf dan fungsi f yang nonkonveks. Pada tesis ini dibuktikan sifat monoton turun dari {T_n (f)} secara generik tidak terjadi pada kelas fungsi nonkonkaf f, serta secara generik, barisan itu juga tidak monoton naik pada kelas fungsi nonkonveks. Meskipun demikian, sifat generik mengakibatkan bahwa untuk sebarang fungsi f baik di kelas fungsi nonkonkaf maupun nonkonveks, terdapat fungsi g yang menghampiri f sedemikian sehingga ekor barisan {T_n (g)} bersifat monoton. Ditunjukkan pula bahwa himpunan fungsi naik nonkonkaf dengan {T_n (f)} yang tidak monoton turun dense terhadap kelas fungsi naik nonkonkaf f. Hal tersebut juga ditunjukkan untuk himpunan fungsi turun nonkonkaf terhadap kelas fungsi turun nonkonkaf. Lalu, dibuktikan bahwa himpunan fungsi naik nonkonveks dan himpunan fungsi turun nonkonveks dengan {T_n (f)} yang tidak monoton naik, berturut-turut dense terhadap kelas fungsi naik nonkonveks dan turun nonkonveks. Himpunan-himpunan yang dense tersebut mengartikan bahwa setiap fungsi f pada kelas-kelas tersebut, dapat dihampiri oleh suatu fungsi g yang bersesuaian dengan kelas-kelas tersebut sedemikiam sehingga barisan {T_n (g)} tidak monoton., Bernhard Riemann defined definite integral as an area under the curve of a real nonnegative function on a closed bounded interval. The alternatives that can be used to estimate the area are Darboux sum which is sum of rectangular areas and trapezoid sum which is sum of trapezium areas. Trapezoid sum is better than Darboux sum as approximations toward the integral of well-behaved functions. Let f be a real valued continuous function on interval [a,b], f is Riemann integrable if and only if it is Darboux integrable. In this master’s thesis, it showed that f is Riemann integrable if and only if it is trapezium integrable. Let f be a real valued continuous function on interval [a,b]. For each partition P_n that divides the interval [a,b] into n equal length subintervals, defined trapezoid sum T_n (f) which is the total of n trapezium areas as an approach of integral value f on [a,b]. If f is a convex function then the trapezoid sum sequence {T_n (f)} is decreasing
Keyword: monotonicity, nonconcave, nonconvex, trapezoid sum