مجله دانش آزمایشگاهی ایران
سال هشتم شماره 3 (پیاپی 31، پاییز 1399)

A regular independent assessment of the technical performance of a laboratory is necessary to assure the validity of measurements or tests. A common approach to this independent assessment is the use of independent Proficiency Testing (PT) schemes that this test great help to the participants to assess the accuracy of its measurements. Therefore, the establishment of national and international ISO/IEC17025 standards is one of the most important goals of calibration laboratories, that all of its legal requirements are based on statistical analysis and it involves recognizing laboratories of the knowledge of test methods and recognizing the behavior of measuring devices which is measured by various tests and ultimately expressed the satisfactory collection. Although, satisfactory performance and vice versa does not necessarily mean the competence or incompetence of a laboratory complex, However, these results can be used to improve the quality of performance.

Optical emission spectroscopy is one of the old methods of studying materials that is used for quantitative and qualitative analysis of metals, alloys, rocks, minerals, etc. In this method, the detection limit in picograms is achievable for many elements. The basis of the operation of this method is based on electron excitation, change in electron energy level and emission of photoelectrons. The amount of energy of the emitted photoelectrons is the identity of the material. The quantometer is one of the devices that uses this technology. This device includes the excitation source, the photoelectron separator section and the detector section. The separator uses grating technology and the detector uses photo multiplier tube technology.

Discontinuities usually rule the mechanical behavior of a rock mass. The free surface of geotechnical structures such as dam foundations, powerhouses, slopes, and tunnel walls, are also significantly affected by discontinuities. Besides, when the intact material is relatively strong, the effect of discontinuities and their properties would even increase. The direct shear test is a well-known test for determining the shear strength of saw-cut surfaces and natural joints of rocks, which provide the most valuable results for engineering design parameters. The shear strength of concrete layers in Rolling Compacted Concrete dams (RCC dams) is also considered a crucial engineering design parameter. This parameter is additionally determined by direct shear testing on the cored samples of a dam body. The in-situ direct shear test is the most precise direct shear test, among other direct shear test types. However, due to the enormous costs and difficult executive operations of the in-situ direct shear test at sites, the direct shear test would be conducted in the laboratory most of the time. The laboratory direct shear test could be conducted at small and large scales. In case that the subjected project has great importance, by using the large scale laboratory direct shear test, more precise results would be acquired. For this purpose, the Azmouneh Foulad Consultant Engineers Co. has designed and manufactured a large scale direct shear box that can be used for more accurate simulation of the in-situ direct shear test. This shear box, which is unique in its category, is capable of 35×35 cm samples testing.

As mentioned in previous article published in Iranian Journal of Laboratory knowledge (No. 30-Summer 2020) With the title of ‘An introduction to In-situ Environmental Transmission Electron Microscopy equipped with a gas-controlled environment operational principals and structures’ unlike Conventional Transmission Electron Microscope, samples inside in-situ Environmental Transmission Electron Microscopy (ETEM) equipped with controlled gas-environment can be exposed to different gaseous species, pressures and temperatures. Such approach provides researchers with unique opportunities to achieve new level of material analysis. This kind of microscopy is considered valuable equipment for understanding the behavior of different specimens in atomic scale. In-situ ETEM with gaseous environment makes it possible to acquire dynamic measurements of nanostructures during reaction processes and also to follow the structural and chemical changes under different atmosphere, pressure and temperature conditions. Extensively used gaseous species in various research and industrial fields have a significant effect on both the configuration of solid materials and the evolution of reactive systems. Various nanomaterial-based technologies, such as food production, efficient energy conversion, transportation, and environmental protection are dependent on In-situ ETEM for achieving accurate real world results. In order to gain new insights into the growth, properties, and functionality of nano-materials such as biological specimens, catalysts, and fuel cells, obtaining practical information from gas–solid interactions accrued from In-situ ETEM is essential. Thereby in this article some of the more important applications of the ETEM when using a gaseous environment will be reviewed.

Liquid sample introduction is referred to as the Achilles̕ heel of atomic spectrometry in view of the achievable aerosol transport efficiency, matrix sensitivity of nebulizer, its ease-of-use and its applicable ranges of gas and liquid flow rates. It is accepted, that the technology used for liquid sample introduction is still far from ideal system. The miniaturization of systems utilized for sample introduction has become a major trend. The reason for this might be increasing need to cope with minute amount of sample to be analyzed and to establish the hyphenation of low flow separation techniques with analysis instruments. A large number of novel nebulizers was presented based on classical but further developed and improved approaches for minute amount liquid sample nebulization e.g. the micro-concentric and direct injection designs. Micro nebulizers produce fine aerosols at low sample uptake rates, but they are even more prone for blocking or clogging than conventional systems. Novel nebulizers based on different approaches and techniques were introduced to eliminate this problem. In this paper we will explore different types of pneumatic nebulizers.

Electroencephalography refers to the measurement of electrical changes in the brain that indicate spikes, transient currents, random events, and rhythms. Neurotherapy uses brain anatomy, psychological tests, behavioral measurements, and records the patterns of specific brain activities, with a focus on the rhythms and activities of delta, theta, alpha, beta, and gamma frequency bands as well as sensorimotor rhythms. The synchronous and asynchronous pattern of these frequency bands describes specific cognitive and behavioral states of an individual. Therefore, cortical involvement can be identified by measuring the combination of slow and fast rhythms in different parts of the head. Although EEG has a high temporal resolution, it cannot be used as a single imaging technique to study brain function due to the poor spatial resolution. In recent years, several non-invasive high-resolution spatial brain imaging techniques, including Positron Emission Tomography, Computed Tomography, and Functional Magnetic Resonance Imaging have developed to enhance understanding of the function of the human brain. Despite the desirable spatial resolution, these methods have an unfavorable temporal resolution. Therefore, to better understanding the brain function and studying deeper structures of the brain, EEG can be combined with any of these imaging methods. On the other hand, the analyzae of the frequency of EEG signals by identifying abnormalities in the neuronal function of the brain allows the integration with magnetic stimulation of the brain and neurofeedback for cognitive and behavioral enhancement. In this study, we introduce EEG and integrate it with non-invasive methods to identify the relationship between brain structures and abnormal patterns of neural activity, as well as improving the cognitive-behavioral function due to EEG neuroprocessing interventions.