| Nama Pengarang | : | M.M. Yetty Tjandrawati |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 67-74 |
| Abstraksi Narasi | : | Corrosion of iron and aluminium in some liquid solutions has been studied from thermodynamic and electrochemical point of view. It was found that iron would be much corroded in acid rain. Corrosion of aluminium was impeded by Al2O3, but since chloride ion could penetrate Al2O3 aluminium could be corroded by oxygen and water. |
| Nama Pengarang | : | Yosef Wijoyo, Tjandrawati, M.M. Yetty, Damanik, Asan, Maria Agustiani, PK Purwadi, Wilardjo, Priyatma, J. Eka, Budi Jumpowati, Maria Dwi, Sri Agustini Sulandari, Maslichah Asy''ari |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 81-87 |
| Abstraksi Narasi | : | In their life humans are susually in contact with other living organisms, such as microorganisms, bacteria, fungi, viruses, parasites, etc. Infection occurs when microorganism`s invasion to the human body causes physiological disorders. The chemical substances used in infection eradication are antibiotics. The antibiotics found in commercial use are formulated in miscellaneous dosage forms, strength and quality and are marketed in relatively high prices. Because of the product`s diversity, antibiotic users deserve comprehensive product knowledge as guidance in using antibiotics in order to avoid the drug`s misuse. This article discusses important information regarding antibiotics and the negative impact induced by antibiotic misuse. |
| Nama Pengarang | : | Frans Susilo |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 67-79 |
| Abstraksi Narasi | : | One form of uncertainty, which results from information deficiency, is the ambiguity whether a particular element of a universe X belongs to a crisp subset of X or not. In this case we need a measure to indicate the degree to which the available information supports the evidence or belief that the element belongs to the subset. Such a measure is called fuzzy measure. Within the framework of fuzzy measure theory, evidence theory and possibility theory, which initially were intuitively developed by L.A. Zadeh in terms of in terms of fuzzy sets, will be discussed. A comparison between possibility theory and probability theory will be presented as well. |
| Nama Pengarang | : | St. Susento |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 80-88 |
| Abstraksi Narasi | : | Mathematical aspects of the postulates of quantum mechanics, specially related to physical quantities with discrete spectrum, are discussed. In order to facilitate the discussion, we formulate some prerequisites from linear algebra, such as abstract vector space, linear functional and operator, eigen value/vector, and Hermitian operator. |
| Nama Pengarang | : | Alb. Setiyoko |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 61-66 |
| Abstraksi Narasi | : | A theoretical study of calculation of compressibilityand Bulk modulus of several metals has been done using electron gas model. The results of this study show that Bulk modulus of AI, Cu and Ga is in agreement with the experimental results available in the literature, but Bulk modulus of other metals with different electronic configuration is not. |
| Nama Pengarang | : | Riswaka Sudjaswadi |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 12-23 |
| Abstraksi Narasi | : | Although chloramphenicol is a broad-spectrum antibiotic, the usage becomes restricted because of its dangerous side-effects in the longer application and larger doses. It is necessary, therefore, to study the formulation development in order to improve the effectiveness in smaller doses that will decrease the side-effects. Chloramphenicol was dispersed in the equal amounts of poliethylenglicol 4000-Tween 80 (PT) prepared in the range of mole fraction 0,0 to 1,0. The solid dispersion, then, was determined by infra-red spectrophotometics, followed by thermal analysis using the Differential Scanning Calorimetry (DSC) for the selected mole fraction solid dispersion (0,0; 0,1; 0,5; 0,9 and 1,0). The bactericidal effect on Staphylococcus aureus and Escherichia coli were studied by diffusion methods. The results showed that the infra-red spectrograms indicated differences at the peaks of carbonyl of chloramphenicol and PT, also at amide of chloramphenicol. Data of DCS thermograms of the selected mole fraction were also similar, i.e. they indicated differences at the peaks showing the melting points from the pure drug. The bactericidal effects of samples were studied by using diffucion methods on the definite micro-organisms, and the results indicated that the effectiveness was significantly improved in comparison to that of chloramphenicol. In conclusion, the organic molecular complex interactions seemed to occur and the solid dispersion dosage forms gave higher effectiveness in the bactericidal effects. Further studies are necessary to be set up. |
| Nama Pengarang | : | Linggo Sumarno |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 45-52 |
| Abstraksi Narasi | : | Digital FIR (Finite Impulse Response) filtering with an overlap-save method was originally based on FFT (Fast Fourier Transform). DCT (Discrete Cosine Transform), which is frequently found in lossy data compression, can also be used as an alternative. The simulation of digital FIR filtering with an overlap-save method based on DCT shows that DCT has the ability to replace FFT. This ability, however, must be compromised with some worse filtering performance such as ripple and attenuation in the pass band. |
| Nama Pengarang | : | lmono Argo Donatus |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 1-11 |
| Abstraksi Narasi | : | A rational approach to elderly therapy needs a comprehensive understanding on various changing pharmacokinetic and pharmacodynamic profiles during ageing processes. These two profiles are interrelated, and affect the availability of the drug in a certain side of action and the effectiveness of the interaction with their cells` target. Furthermore, this will determine the performance of drug`s pharmacology and toxicology. As for the decision on elderly, it is suggested that the therapy should not be based only on the consideration of drug`s fate during ageing processes, but also on that drug`s fate due to complicated illness, polypharmacy habits, environment (smoking), and nutritional status, which are basically difficult to distinguish from the ageing processes. |
| Nama Pengarang | : | Budi Setyahandana |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 30-44 |
| Abstraksi Narasi | : | The tensile test measures the resistance of material to a static or slowly applied force. In this test we obtain a yield strength, which is the stress at which plastic deformation becomes noticeable. A component is often subjected to repeated applications of stress below the yield strength of the material; nevertheless, the material may fail after a large number of applications of the stress. This mode of failure is called fatigue. in this paper, we discuss the tensile and fatigue test of ST-37 steel that can be found in shops in Yogyakarta. The results of these tests are the tensile and fatigue characteristics together with their correlation. |
| Nama Pengarang | : | Asan Damanik |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 53-60 |
| Abstraksi Narasi | : | The effect of Fermi resonance to the wave number difference between V3 and V1 transitions, and between V3 and 2V2 transitions, for three kinds of carbondioxide isotope molecule, has been provided. Using the Fermi resonance effect, the theoretical wave number difference between V3 and V1 transitions is in agreement with the experimental results reported by Bradley et al (1987). On the other hand, the theoretical wave number difference between V3 and 2V2 transitions is in agreement with the experimental results if it is calculated without using the Fermi resonance effect. |
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