| Nama Pengarang | : | Lestyo Wulandari |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 105-109 |
| Abstraksi Narasi | : | The cromatograpghic efficiency of HPTLC plate better than the conventional TLC plate, but unfortunately it is more expensive. Due to the higher price of HPTLC plate compared to the conventional TLC plate, the application of reused HPTLC plate has been tested. After being used for analyzing samples, the plates were developed again with the mobile phase, then were dried for 60 minutes before being used for the next measurement. The qualitative chromatography profile showed that reused HPTLC plate has less contaminant than the new plate and the RSD of the precision quantitative testing of the plates reused three times showed a value which is greater than 2%. |
| Nama Pengarang | : | Nita Suhartini, Barroca Aliyanta, dan Ali Arman Lubis |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 199-205 |
| Abstraksi Narasi | : | Investigation of erosion rate estimation has been done using environmental isotope 137 CS. Radiogenic 137 Cs contents of the soil can be used to estimate the maount of erosion/deposition in an area with respect to the stable reference site. The investigation aimed to estimate erosion/deposit rate in small cultivated site using ridge and furrow system located in Puncak Bogor. Sampling of soil was done by using scraper (20 x 50) cm for reference site, and coring (di=7cm) for investigation points. Two small cultivated sites were chosen, namely TS3 (50x60)m, and TS5 (50x60)m. The result showed taht net erosion for TS3 and TS5 were -5 t/ha/yr and -39 t/ha/yr, respectively. |
| Nama Pengarang | : | Bowo Eko Cahyono, Misto, Tuti Isnawati, Nita Suhartini, Ali Arman Lubis, Barroca Aliyanta, Lestyo Wulandari, Syamsurijal Rasimeng, Fahru Nurosyid et al, Dwiretnani Sudjoko, Budiantara, I Nyoman, Mulianah, Sumarno, Linggo, D. Asmi, I. M. Low, B. O`Connor, Anastasia Rita Widiarti, Yosaphat Sumardi, Jumina |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 133-140 |
| Abstraksi Narasi | : | The aim of this research is to design and implement a lamp controller system using AT89S51 microcontroller. The system consists of microcontroller hardware and software working on PC. The hardwares are AT89S51 microcontroller lamp and light sensor series using LDR. RS 232 was used to establish communication between the PC and the system, in order to control the lamp and display the results on the monitor. The result of the research showed that the software in the microcontrollers, as well as in the PC, was running well, leading us to the conclusion that the lamp controller can be used in real life. |
| Nama Pengarang | : | Imam Rofi |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 15-23 |
| Abstraksi Narasi | : | In this research, damage profiles of random implanted SI-GaAs samples were investigated using Rutherford Backscattering (RBS) Channeling Spectrometry. Random implantations were performed using 400 keV germaniumions with several ion doses, namely: 3x10.. , 1x10.. , 3x10.. , 1x10.. , 3x10.. , and 1x10.. ions/cm . The effects of ion doses on the crystal structures of GaAs samples were studied. The results showed that RBS yields were monotonically effected by the ion dose of implantatios. The damage profiles of GaAs samples were also compared and analyzed using TRIM 98 calculation. These results clearly indicated that the RBS profiles corresponded to the damage induced by ion implantation in the GaAs samples. |
| Nama Pengarang | : | Irwan Ginting Sukadan Wasinton Simanjuntak |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 35-44 |
| Abstraksi Narasi | : | Linear low-density polyethylene (LLDPE) film grafted with epoxy-bearing polymer, poly(glycidyl methacrylate) (polyGMA), which is known to have high reactivity for numerous functional groups such as alcohols, hydroxyl, and amine groups,was prepared by the photografting (...> 300 nm) method. Xanthone was used as a photoinitiator by coating it on the film suface. Distribution of the grafted chains in the resultan GMA-grafted film was examined by attenuated total-reflection IR spectroscopy and scanning electron microscopy. The percentage of grafting of polyGMA increased with the concrentation of GMA-grafted films were subjected to amination with ethylenediamine (En) at 70 for 3 h in N, N`-dimethylformamide. It was found that epoxy groups of GMA-grafted chains have the ability to react with En. The aminated epoxy group increased the concentration of En in the system. The aminated GMA-grated film had an excellent ability to adsorb cupric ion. the amount of adsorbed Cu... increased with the increasing of the concentration of Cu... and reached about 0,4 when the concentration of Cu... was 10 mmol/L. |
| Nama Pengarang | : | lkhsan Setiawan, Agung B.S. Utomo, Guntur Maruto, dan Andi R. Wijaya.... |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 25-53 |
| Abstraksi Narasi | : | A simple thermoacoustic device as a heat pump has been successfully constructed and operated. The main parts of the device consist of a cylindrical resonator made of PVC pipe, a loudspeaker as a sound source, and a stack as a heat transfer element. The device ws operated at a resonance frequency of the resonator, i.e. about 151 Hz, using atmospheric air as a working medium. A heat transfer from cold reservoir to hot reservoir has been observed where the cold reservoir temperature decreased about 5...C and the hot reservoir temperature increased about 8...C after 6 minustes of the device operation. |
| Nama Pengarang | : | Benny Yong dan Yose Stefanus |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 71-76 |
| Abstraksi Narasi | : | Option is one of the derivative tools which currently has been undergoing great progress. The option style may vary, such as European option, American option, Asian option, etc. This paper explores the Asian option whose value will be calculated using three methods, i.e. the standard Monte Carlo Simulation, the antithetic variable Monte Carlo, and the control variate Monte Carlo.The results of the three methods will then be compared to each other. The conclution is that the result of Asian call option price from the control variate method is the most accurate one. |
| Nama Pengarang | : | Laksmi P. Maharani dan L Hartanto Nugroho |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 45-53 |
| Abstraksi Narasi | : | A research has been done to investigate the effect of wastewater tempe production on anatomical structure and the content of Beta-Carotene kangkung (Ipomoea reptans Poir) in hydroponics culture. The samples are kangkung treated with wastewater tempe production. There are two combinations of research factor. The first factor is kinds of wastewater tempe production i.e. wastewater A (Wastewater from the process of soy bean washing and soaking) and wastewater B (wastewater from the process soy bean boiling) and the second factor is the concentration of wastewater (0, 25, 50, 75 and 100%). Data was analyzed using analysis of varians for roots rexygen lacuna, the thickness of stems, percentage of palisade in leaves thickness, and Beta-Carotene content. Results show that wastewater tempe production affected the physiology, growth and the content of Bera-Carotene on kangkung grown hydrophonically. The treatment of 100% wastewater A showed good effect on the morphology, physiology, and anatomy of kangkung grown hydroponically. However, the treatmentof wasterwater B showed good effect up to 25% - 50% concentration only. The increase in wastewater concentration was not followed bu the increase in Beta Carotene content. |
| Nama Pengarang | : | PK Purwadi |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 1-13 |
| Abstraksi Narasi | : | The objectives of this study were to find out the effects of Biot number (BI) on the distribustion of temperature in a cubic-shape solid object during the unsteady state and to determine the value of Biot number that generated homogenous distribution of temperature from time to time at all positions. This study was carried out by solving a mathematical model which was suitable to the problem, namely the Fourier equation for heat conduction. It utilized a numerical computation approach using explicit technique of finite difference method. The temperature of the object at initial condition was homogenous. Mean while, all boundary conditions were in contact with the fluid whose temperature (T) and coefficient of convention (h) were kept constant and homofenous from time to time. The specific gravity (p), specific heat (c), and coefficient of heat conduction (k) of the object were assumed fixed or unchanged against the temperature change and were homogenous at all positions or not the function of position. During the process of unsteady state, the object did not experience any change in both form and volume. From the results of this study, we concluded that (1) the higher value of Bi, the less homogenous was the distribution of temperature from time to time; (2) for Bi = 0,01, the distribution of temperature generated from time to time could be considered as homogenous with the value of 0max = 4,23%. |
| Nama Pengarang | : | CJ. Soegihardjo |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 83-102 |
| Abstraksi Narasi | : | Neem (Azadirachta indica A.Juss., family Meliaceae) has attracted world- wide prominence in recent years, owing to its wide range of medicinal properties. Neem has been extensively used in Ayurveda, Siddha, Unani, and Homo and Homoeopathic medicine and has become a complementary and alternative of modern medicine. Neem elaborates a vast array of biologically active compounds that are chemically diverse and structurally complex. More than 140 compounds have been isolated from different parts of neem. All parts of the neem tree, e.g. leaves, flowers, seeds, fruits, roots and bark have been used traditionally for the treatment of inflammation, infections, fever skin diseases, and dental disorders. The medicinal utilities have been described especially for neem leaf. This review givies a bird`s eye view mainly on the bioactivities of some of the neem compounds isolated, pharmacological actions of neem extracts, clinical studies, and medicinal applications of neem along with their safety evaluation. Based on these facts, now it is good time to disemminate all information about neem in traditionally uses for Indonesian people and to encourage scientists for investigating neem. |
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