فهرست مطالب

- پیاپی 41 (بهار 1402)
- تاریخ انتشار: 1402/04/07
- تعداد عناوین: 8
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صفحات 2-5
- استاندارد
- مقالات
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صفحات 13-18
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صفحات 25-36
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صفحات 37-47
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صفحات 48-54
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Pages 7-12
Contamination of soils and water environments with heavy metals is a serious and expanding problem. The entry of heavy metals through human activities has caused the pollution of many soils. Also, contamination of rice with heavy metals and its entry into the food chain can have harmful effects on human health. Arsenic species need to be carefully monitored in food due to their toxicity. In this article, the importance of measuring arsenic in rice by selective hydride production atomic absorption spectrometry, as well as the types of nuisances and methods to solve them, are discussed. The atomic absorption spectrometer must be equipped with an air-acetylene torch, a hydride vapor generator, a quartz absorption tube, an arsenic hollow cathode lamp, suitable for measuring at a wavelength of 193.7 nm.
Keywords: Arsenic, Rice, Atomic Absorption -
Laser Scanning Confocal Microscopy / Part 2Pages 13-18
Biological laser scanning confocal microscopy relies heavily on fluorescence as an imaging mode, primarily due to the high degree of sensitivity afforded by the technique coupled with the ability to specifically target structural components and dynamic processes in chemically fixed as well as living cells and tissues. Many fluorescent probes are constructed around synthetic aromatic organic chemicals designed to bind with a biological macromolecule (for example, a protein or nucleic acid) or to localize within a specific structural region, such as the cytoskeleton, mitochondria, Golgi apparatus, endoplasmic reticulum, and nucleus. Other probes are employed to monitor dynamic processes and localized environmental variables, including concentrations of inorganic metallic ions, pH, reactive oxygen species, and membrane potential. Fluorescent dyes are also useful in monitoring cellular integrity (live versus dead and apoptosis), endocytosis, exocytosis, membrane fluidity, protein trafficking, signal transduction, and enzymatic activity. In addition, fluorescent probes have been widely applied to genetic.
Keywords: Laser scanning confocal microscopy, Fluorescence, Fluorophores -
Pages 19-24
Determination of oxygenated additive compounds like ethanol, MTBE, ETBE and also aromatic compounds like xylenes, benzene and toluene in different kinds of engine fuels and vehicles is very important due to check the quality and environment issues. Regarding to this topic using gas chromatography has a great importance and measuring of these evaporative compounds is easy done by this method. ASTM D6729 is the method for measuring of above compounds in different fuels by gas chromatography. Gas chromatography is an analytical method for separation of evaporative compounds in gas phase. In gas chromatography method the gas components of sample dissolved in a solvent, evaporate between two stationary and mobile phases and then separation happens. Mobile phase is an inert gas that keep moving of sample molecules in the warmed column.
Keywords: Gas chromatography, fuel, hydrocarbon, aromatic, olefin, separation of evaporative compounds, MTBE, ETBE, oxygenate, carrier gas -
Pages 25-36
Part 2The purpose of this article is to explain the role of the laboratory and standard tests in the quality control of seamless cylinders. First, in this part of the article, general and functional tests of seamless cylinders including Ambient temperature pressure cycling, Leak Test, Bonfire Test, Penetration Test, Hydrostatic Pressure Test and other functional tests were discussed and then non-destructive tests such as magnetic particle tests, crack detection and thickness measurement by ultrasonic Test method were investigated. In the following, the specialized tests of type II, III and IV automotive and industrial cylinders, including acid environment tests, Extreme temperature pressure cycling Test, High temperature creep Test, Composite flaw tolerance Test, Accelerated stress rupture Test and others Tests were stated and at the end, the tests of adhesion, flexibility, Coating Thickness measurement and other tests of the protective coating of the cylinders were investigated. Based on the presented materials, regard to the great number of selective Tests and approval procedure that should meet the standards in a Accredited laboratory, as well as continuously quality controls, the reliability and high level of safety of these cylinders are guaranteed.
Keywords: Laboratory, Seamless Gas Cylinders, Compressed Catural Gas (CNG), Materialtests, Mechanical properties tests, Destructivetest, Non-destructive tests -
Pages 37-47
Many grease-lubricated components operate in wet environments, making them susceptible to water contamination which degrades their performance, functionality, and useful life. Hence, selecting a grease with appropriate water-resistant properties can have a significant influence on the life of the machine. While industry standards attempt to evaluate a grease’s water resistance, research indicates that a more thorough understanding of water resistance is needed to properly match a grease to an application. This paper provides an overview of the interaction of grease and water, covers existing water-resistance standards, discusses the results of available experiments aiming to describe the effects of water on grease, demonstrates the need for more meaningful standards, and suggests additional measures for characterizing a grease’s water resistance.
Keywords: grease contamination, water resistance, water contamination -
Pages 48-54
In recent years, Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) and Electrospray-Time of Flight Mass Spectrometry (ESI-TOF MS) have been widely used in different countries. Several thousand types of these devices are used for elemental and molecular analysis from the environmental level to hospitals and various industries, from satellites to the detection of any toxic substance and many other cases are being heavily developed. The heart of these devices is the time-of-flight mass analyzer system, where the ionized samples (with MALDI or ESI or other methods) are flown in this mass analyzer system and, based on the flight time of each ion inside this system (which depends on their mass), are determined by mass. In this report, the theory of the system (TOF), its different types and its advantages and disadvantages are briefly discussed. Also, the use of this method in the analysis of materials, especially macromolecules (synthetic to biological) and other cases of using this method are mentioned.
Keywords: Mass Spectrometry, MALDI-TOF MS, ESI-TOF MS, Biomolecule analysis