مجله دانش آزمایشگاهی ایران
سال دهم شماره 2 (پیاپی 38، تابستان 1401)

According to the statistics of organic agriculture in the world, in 2019, the area under cultivation of organic prouducts in Iran was reported to be 11,916 hectares. This amount has only 0.03% of the share of total agricultural lands with 24 producers of organic products in the country. According to the same report, so far only one producer in the country and only one farm has succeeded in obtaining the International Certification Office of Biodynamic Federation(ICO-Certified). A close look at the above statistics shows the high potential of the country to produce organic products. From the economic point of view, organic products are a very good opportunity for the export of the country's farmers. Creating a legal basis for this type of product is very important. In this regard, in order to legalize organic products in the country and in order to create national and international coordination in determining the requirements for the production of organic products, for the first time in 1387 the national standard of Iran No. 11000 entitled "Requirements for production, processing, inspection, certification, labeling, and marketing of organic food" has been developed by the Iranian National Standardization Organization (INSO). Subsequently, this standard has been revised in 1392 and then in 1399 to maintain synchronization and coordination with national and global developments and progress. In the development of the standard, the production of organic food on the farm, preparation, storage, transportation, labeling, marketing, as well as raw materials allowed for soil fertility and improvement, pest and disease control, plant diseases, food additives and process aids are considered. In this article, while explaining the concepts of organic agriculture, with the introduction of the standard 11000 general requirements for organic product labeling and inspection systems and licensing of organic trademarks and accreditation procedures by the National Accreditation Center of Iran (NACI), is presented.

X-ray fluorescence (XRF) analysis is a reliable and non-destructive multi-element analysis method that is widely used in research and industrial applications. In this article, the advantages and limitations of handheld XRF analysis were discussed. Handheld XRF is portable, requires minimal sample preparation, and responds quickly. For alloy identification, one of the most common applications of XRF is often grade determination, which can be done in less than 40 seconds using handheld XRF. Handheld XRF is capable of quantifying more than 90% of the common alloying elements of the periodic table, from magnesium and heavier, which is about 72 elements. Due to the potential risk of working with ionizing radiation, the analysis should be performed by trained people and following safety precautions.

Confocal microscopy is an established light microscopical technique for imaging fluorescently labeled specimens with significant three-dimensional structure. Laser scanning confocal microscopy has become an invaluable tool for a wide range of investigations in the biological and medical sciences for imaging thin optical sections in living and fixed specimens ranging in thickness up to 100 micrometers. Modern instruments are equipped with 3-5 laser systems controlled by high-speed filters, which allow very precise regulation of wavelength and excitation intensity. Coupled with photomultipliers that have high quantum efficiency in the near-ultraviolet, visible and near-infrared spectral regions, these microscopes are capable of examining fluorescence emission ranging from 400 to 750 nanometers. Instruments equipped with spectral imaging detection systems further refine the technique by enabling the examination and resolution of fluorophores with overlapping spectra as well as providing the ability to compensate for autofluorescence. Recent advances in fluorophore design have led to improved synthetic and naturally occurring molecular probes, including fluorescent proteins and quantum dots, which exhibit a high level of photostability and target specificity.

Since its development, conventional transmission electron microscopy (CTEM) has long been an indispensable tool for wide range of various fields of research. Through the decades, TEM has undergone a number of revolutions, such as: development of cryogenic TEM, in-situ TEM Equipped with gas or liquid cell, aberration correction for atomic level imaging, and so on. One of the most important developments is the ability to observe and image specimens in liquid phase with unprecedented spatial and temporal resolution. Maybe you ask yourself why do we want to image a sample in liquid environment? To answer this question we need to first understand the limitations of CTEM. CTEM requires the sample be stable in high vacuum, thus samples must be dried, which works well for some materials but not all of them. In order to endure UHV specification of CTEM, other materials must be embedded in resin or be flash freeze. All these methods have the potential to introduce artifacts during the preparation process, to observe real-time dynamics, ش but more importantly they immobilize the sample making it impossible such as: growth, interactions, and corrosions. In addition to observing dynamic processes, there are many other types of hydrated or liquid materials that can benefit from direct aid imaging in their native hydrated state, such as: paints, oils, cosmetics, nanoparticles, biological specimens, … . In-situ TEM equipped with liquid cell provides the opportunity to examine samples in their native state (in this case: liquid environment) and track occurrence of any dynamic process in real-time. Now researchers are able to perform heating, electrochemical, static, flow, and liquid mixing experiments with a single liquid cell holder and gain a much needed insights into nanomaterial synthesis and manipulation, battery science and biological cells. The efficient fabrication of functional nanomaterial in many cases depends on the in-depth understanding of the early processes during synthesis. This early period of synthesis typically related to the nucleation at early growth stage has a profound influence on the characteristics of final products (e.g.: nanoparticle size distribution, morphology, composition, and crystal structure). In this article, we study various applications of in-situ TEM equipped with liquid cell to provide the readers with better understanding of its functions.

Plate loading test (PLT) is one of the most useful tests in geotechnical studies. The application of the results of this test, due to its nature, is very important in designing the foundation of structures and estimating settlements after the construction of the structure. In this test, an attempt is made to determine the strength and stiffness of the soil according to the construction material of the site. The purpose of this test is to help determine the important geotechnical parameters of the soil, including the modulus of elasticity. In general, the elasticity modulus is calculated using laboratory results, field tests, and empirical relationships and correlations. Field tests are much more reliable than laboratory tests due to less disturbance of soil. In this article, Isfahan metro line 2 with 24 km long, has been divided into different stations and Plate Loading Test (PLT) has been done in the mentioned areas. Based on these studies, the amount of soil elasticity modulus increases with increasing depth due to the increase in the density of soil layers.

Natural sources are one of the main sources for drug discovery and identification and isolation of natural compounds with biological properties. Due to the existence of different diseases and the creation of new diseases, new drug discoveries are important. The compounds of natural origin are divided into primary and secondary metabolite categories. Most of the production compounds of various microorganisms, especially fungi and bacteria, will be very important due to their rapid growth and exogenous secondary metabolites. Moreover, the comprehensive metabolomics studies of fungal and bacterial colonies are important sources of drug discovery. Natural compounds are examined in two qualitative and quantitative methods. Qualitative and quantitative analysis of compounds is done based on microchemical studies based on precipitation or characteristic and spectrophotometry. The process of separation of the natural compounds is done using many methods, salting out and chromatography methods are among the most important applied methods. The aim of this study is the analysis of metabolomics of fungal and bacterial compounds using gas chromatography-mass spectroscopy method to discover new drugs. GC-MS device has the ability to analyze and identify compounds in extracts and other natural sources due to having a library of compounds. In this technique, the analysis compound must have a boiling point lower than about 250 oC or escape with the derivatization process to be analyzed by this metho