Judul: Perbandingan kualitas layanan pada protokol VOIP H.323 dan SIP
Abstrak: Voice over Internet Protocol (VoIP) adalab suatu teknologi yang dapat mentTiznsmisikan pesan sum melalui jaringan data (internet protocol). Rotokol VolP yang banyak digunakan saat hi adalah H.323 dm SIP. SIP dikembangkan oleh Internet Engineering Task Force's (ETF) yang dituangkan dalam RFC2543 dm H.323 dikembangkan oleh International Telecommzrnication Union (ITU-T). Perbedaan yang mendasar mtara kedua protokol tersebut adalah format data yang ditransmisikan, H.323 menggunakan format binary, sedangkan SIP menggunakan format text (ASCII).
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Judul: Peningkatan Kualitas Layanan VoIP pada Jaringan MPLS Melalui Pengaturan Prioritas
Abstrak: Multi Protocol Label Switch (MPLS) is a method of sending data packets through a network by Label Switching concept. This concept is implemented by adding an independent and unique label in a row of data packet (a packet of Internet Protocol). The function of this label is to graft and to search for a path in the network. Applications that passed through the MPLS network are vary including VoIP, email, ping, internet browsing, etc. With the existence of this labeling function, MPLS can give priority to scale applications to pass through. This research aims to improve the performance of MPLS networks using priority settings on VoIP services. The results obtained when the VoIP service priority settings applied to the MPLS network is that it decreases the ping delay value of 44.75%. And also, the quality of service becomes more stable due to impairment of the jitter standard deviation of 73.44%.
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Judul: Heterologous Expression Of Endo-Β-Xylanase From Bacillus Pumilus Strain Bcrs-01 In Escherichia Coli.
Abstrak: Xylanases are glycoside hydrolase family 11 which depolymerise xylan in the plant cell wall, the most excessive form of hemicellulose. Endo-β-xylanases (EC 3.2.1.8) are most important to breakdown β-1,4-glicoside bond of xylan to produce disaccaride xyloolygosaccaride (XOs) and xylose (monomer). Bovine rumen fluids have potential to obtain endo-β-xylanase produced of bacteria. The objectives of this study were to obtain xylanase producing bacteria and to express xynA gene encoding endo-β-xylanase from bacterium in Escherichia coli. Twenty nine isolate bacteria have been succesfully isolated from bovine rumen fluid in agar medium containing birchwood xylan. Isolate BCRS-01 bacterium was previously screened for the high production of xylanase. Based on 16S rRNA gene sequence analysis, BCRS-01 showed high similarity (99%) to Bacillus pumilus (accession number NR043241). The crude xylanase had optimal activity at 55oC, pH 7.0. Furthermore, the crude xylanase exhibited broad pH stability from 4.0 to 10.0 and remained more than 60% and 40% of its activity after incubation at pH 4.0 until 10.0, respectively for 60 min. It also showed a stability at temperature 25-50oC since it retained 80% and 50% of its activity when incubated at 50oC or 30 and 60 min, respectively. The xylanase activity was strongly inhibited by Ca2+ and Cu2+ at concentration 10 mM, and as little as 1 mM for Mn2+. Therefore, this xylanase has potentially used as additive feeds in animal feed industry. The DNA sequence xynA gene encoded endo-β-xylanase was amplified and cloned into the expression vector pET-15by under the control of T7 promoter. The recombinant protein had succesfully expressed in Escherichia coli BL21 (DE3) pLysS. A protein recombinant of approximately, 26.7 kDa was observed on the SDS-PAGE analysis. Crude extract of recombinant endo-β-xylanase demonstrated activity of enzyme at 56 U mL-1 using birchwood xylan as a substrate at 55oC for 10 min.
Keyword: Bacillus pumilus, bovine rumen fluid, endo-β-xylanase, heterologous expression.