| Nama Pengarang | : | Pulung Karo Karo, Simon Sembiring |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 167-176 |
| Abstraksi Narasi | : | This research was carried out to investigate the comprehensive information on the carbon dioxide corrosion of steel by cetylamine inhibitor at various concentration. The experimental results show that corrosion rate and weight loss of steel decrease significantly with increasing inhibitor concentration. Additionally, x-ray diffraction (XRD) pattern revealed that the formation of corrosion products (scales) on the surface, namely sierite (FeCO3), cementite (Fe3C), calcite (CaCO3), and lepidocrocite (FeOOH) were dependent on the cetylamine concentration. Scanning electron microscopy (SEM) analysis shows taht microstructure of corrosion scales on the surface treated with inhibitor are thinner without cracking than those treated without inhibitor. From these results, cetylamine inhibitor is tenaciously adsorbed to steel. |
| Nama Pengarang | : | JB Budi Darmawan |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 69-76 |
| Abstraksi Narasi | : | The main objective in developing a database is to enable many users to access shared data concurrently and to maintain consistencies. MySQL proposes to use functions to update records in a single operation in order to update data in one record in one table. This technique is not appropriate if data type of the data is large size, such as text or longtext. This paper proposes timestamp technique to support the update more efficiently. The technique has been tested in news editing process case using MySQL relational database. This technique could be used to update one record in one table and if a process involving reading the record followed by writing it exists, it should take more than one second. |
| Nama Pengarang | : | Kusman dan Mardi Santoso |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 9-12 |
| Abstraksi Narasi | : | Marine environments are a rich source of indole alkaloids with a wide spectrum of biological activities, for instance 3,3-bis(3'-indolyl)-2-indolinona sho¬wed antibiotic activity. Reaction of 5-hydroxyindole with isatin has been investi¬gated to afford 3,3-bis(5'-hydroxyi-3'-indoyil)-2-indolinona, a 3,3-bis(3'-indolyl)-2-indolinona derivative. |
| Nama Pengarang | : | Agus Purwadi, Suryadi, dan Widdi Usada |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 97-105 |
| Abstraksi Narasi | : | Ozone (03), a new chemistry molecule with strong oxidance and chemistry potential of 2.07 eV, has positive prospect to be apllied in the industry and enviromental fields (e.g. sterilization of gas and fluid waste) as well as in the agricultural chemistry fields (e.g. sterilization of the seed and fruits-vegetables processing). A Dielectric Barrier Discharge Tube (DBDT) as the main component of the ozon generator has been designed and constructed. Ozone is formed by atmospheric pressure with discharge voltage of 25 kV and frequency of 1,5 kHz. The measurement results of one of the DBDT are secondary current value of 1,34 mA and secondary voltage of 18,38 kV, yieding the power value of 24,63 watt, which is approximating the 25 watt power value required. Ten units of 250 watt plasma ozonizer consisting of 100 watt DBDT and 150 watt DBDT have been constructe |
| Nama Pengarang | : | Akhmad Ammuddin Barna , Muslim, M. F. Rosyid, M. Satriawan |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 19-30 |
| Abstraksi Narasi | : | An investigation is carried out on inequivalent quantizations and statistics for a quantum mechanical system of identical particles occupying a topological space-time M undergoing spatial topology changes. In this paper, a new concept has been introduced related to the construction of inequivalent quantizations for a system, which is called "history-like path" for particles. This is a collection of non-causal homotopical paths. Each homotopy class of paths will be labelled with a "word" constructed from the generators of fundamental group ,7r1(QN(Ei)) of a configuration space of the system in a space-like £ which is a deformation retract of M; region that is a sub-space-time of M in which there is no singular slice (a slice MM in M that contains a singular point). The labels determine the generators and their relations in constructing the fundamental group ,'z (QN) of the system. By using the new concept, two methods are proposed to construct inequivalent quantizations of a system of identical particles undergoing a spatial topology change, either via a "local-local" (L-L) or a "global-local" (G-L) quantization. The first method corresponds to constructions of inequivalent quantizations of the system in each region M; in M. Each of them is in a (1-1)-correspondence with irreducible unitary representations (IUR's) of a fundamental group .7r1(QN(i i)) BN(.2) constructed by generators in each of the regions corresponding to the possible history-like homotopy paths. A possible statistics for N-identical particles in M is determined by a sub-representation of IUR of braid group BN(.). The sub-representation is a representation of a subgroup _N(£) which is a subgroup of BN(E) only generated by permutation of particles. The second method is based on a construction of inequivalent quantizations of the system in M. They are in the (1-1)-correspondence with IUR's of the fundamental group .7r1(QN(2)) = BN(2) raised by generators corresponding to the history-like homotopical paths of the system in M; and these inequivalent quantizations are considered valid for all regions M; in M. A possible statistics for N-identical particles in M is determined by a sub-representation of IUR of braid group BN(.), i.e. a representation of cN(') C BN(2). |
| Nama Pengarang | : | Waluyo, Sabat Anwari, dan Yudha Eko Prayitno |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 77-96 |
| Abstraksi Narasi | : | A control system of automatic voltage regulator for tap-changer operation on a power transformer has been designed. This system used an A T89S51 series microcontroller as the main control unit of relays connected to the motor-drive of tap-changer. The operation principle of the microcontroller was on-off action. The microcontroller activated the relays and sent information to a computer, based on conditioned signal given by a sensing unit. This signal was converted to digital signal by an analog-to-digital converter of ADC0804 series. A testing of hardware and software was conducted. The input voltage was varied, up and down, from nominal voltage of 110 Volt, causing the rotor of motor and relay positions change accordingly. The change of voltage and relay positions could be seen on the software display using Visual Basic programming. The hardware and software were able to integrate and operate properly. |
| Nama Pengarang | : | Muslim Ansori , Yosephus D. Sumanto |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 31-41 |
| Abstraksi Narasi | : | We construct Henstock-Kurzweil integral for Riesz-space-valued functions defined on Euclidean space R" by a technique involving double sequences and prove some basic properties among which the fact that our new integral coincides with the Henstock-Kurzweil integral for Banach-space-valued functions defined on the space R" . Further, some convergence theorems are built using this integral. |
| Nama Pengarang | : | Oman Zuas |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 1-7 |
| Abstraksi Narasi | : | Evaluation of the storing effects of soil samples containing VX and screening of its degradation product have been done. The soil samples were spiked at the concentration level of 5 ppm and were then extracted using cold water extraction method (pH 2 at 4°C). The VX was quantitatively analyzed by means of LC-MS/MS using selected reaction monitoring (SRM, while its degradation product were identified using multiple reaction monitoring (MRM). The storing effect evaluation has shown that the VX can still be identified after stored. The yields after stored for 1 hour, 2 and 4 weeks were 58, 19 and 12 %, respectively. Bis[2-(diisopropylamino) ethyl] disulphide and ethyl methylphos¬phonate were identified as degradation products of VX. This study confirmed that cold water extraction was a useful method to detect the VX and its degradation product in soil sample when LC-MS/MS technique was applied. |
| Nama Pengarang | : | La Aba |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 13-18 |
| Abstraksi Narasi | : | A research on solar energy absorber's surface characteristics and its application as a water desalination has been done. The specific aim of this research is to investigate the effect of form and thickness of solar energy absorber to solar still performance. The results of this research show that the wave form and the thickness are most effective to improve the solar still performance. |
| Nama Pengarang | : | L. Hartanto Nugroho, Amalin B. Setiani, dan Sutikno |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 53-68 |
| Abstraksi Narasi | : | Due to the potential role and urgency of ginger as natural medicine mate¬rials, a research of ginger varieties has been done. It consists of the anatomical structure and the essential oil's chromatogram profile of rhizome and leaves of four ginger varieties, namely emprit, gajah, kapur, and merah ginger. The samples used in the research were taken from 7 month-old and fresh plant, so that the secretory cell structure and essential oil produced have not been destroyed yet. Water distillation method was used to isolate the essential oil of the rhizome and leaves. Ethyl acetat was used to separate oil from water phrase. The distillate was injected in GC-FID to get the chromatogram profiles. The results indicated that the anatomy structures of the rhizome and leaves of four ginger varieties have similar characteristics. Rhizome secretory cells were distributed in cortex and stele. In general, there are more essential oil cells in the cortex than in the stele. The secretory cells in the leaves were distributed in epidermic tissues. In general, there are more essential oil cells in the abaxial epidermic than in the adaxial ones. The profile of chromatograms demonstrated that the essential oil of emprit rhizome is the most complex one with 39 different time-retention peaks, while the essential oil of kapur leaves is the most complex one with 22 different time-retention peaks. Based on the essential oil peak area and compound concentration in the rhizome, the kapur and merah ginger have closed relationship, followed by gajah and emprit ginger. On the other hand, based on essential oil peak area and compound concentration in the leaves, the emprit and merah ginger have closed relationship, followed by kapur and gajah ginger. |
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