Basic Divergent clay soils are soils that have high percentage of sodium ions. The soils prone to leaching when placed under water seepage and erosion. In this research, the impact of crude oil as a side effect of pollution (possibly positive) on the amount of divergence of the soil will be discussed. Therefore, first soil artificially by adding a solution of sodium hexametaphosphate were divergent and then some pinhole test on soil samples with different amounts of crude oil diverged (1, 3, 5 and 7%) were performed. In addition to this, the effect of crude oil pollutants on the shear strength and uniaxial testing was conducted to help. Results obtained showed that with presence of oil and increase in percentage of oil and the time of soil and oil contact, dispersivity of soil decrease. Thus with gradual increase of oil, the territory is quite divergent soil became non-divergent. Also the, single pivot (uniaxial )tests experiments showed that at the first samples strengths increase to 3% oil content and more oil quantities reduces the the resistance of the soil.

Introduction: Loess soils are a special type of silty soils with a porous structure and weak adhesion. In case of improper management, loess soils are the most sensitive soils to erosion and are easily washed away by heavy rains. One of the most important influencing factors in the vulnerability of loess soils is the phenomenon of dispersion. during which the soil floats in it as a result of contact with water and is removed from the environment by the force of the water flow. Many studies have been conducted by researchers to investigate dispersive soils. Providing a suitable improvement method for them requires the correct determination and diagnosis of the degree of divergence in the studied area. The complete identification of dispersive soil also depends on a detailed test. As a result, various methods have been presented to identify soil dispersion. The most significant of which are the pinhole, chemical, crumb and double hydrometry methods. So far, there is no general consensus regarding prioritizing the use of dispersion tests. Considering the importance of the issue of divergence on the quality of soil and agricultural products, in this research we try to investigate the accuracy of different tests in detecting soil dispersion.Materials and Methods: This research was focused on loess soils of Golestan province. seven pedons were selected, sampled and described in different parts of the province. Physicochemical properties of soil such as texture, density, pH, solutes in soil, etc. important measurements and tests to determine soil dispersion potential such as pinhole, chemical, crumb and double hydrometry tests were performed based on ASTM standards. Finally, the validation of the tests was done based on the comparison of their results with each other.Results and Discussion: The results show that the percentage of organic Carbon and soil porosity decreased from the surface (horizon A) to the depth of the soil (horizon B and C), while the apparent specific mass increased. Therefore, the change in soil properties from surface horizons to depth has caused a change in the degree of dispersion of these horizons. On the other hand, high amounts of exchangeable sodium in some horizons caused chemical dispersion, which indicates the role of sodium in increasing the thickness of the double layer of clay soil surfaces. However, the results of this research indicate that there is no severe dispersion of loess soils in Golestan province.On the other hand, the dispersion tests performed on these soils show that the dispersion phenomenon caused by the presence of sodium does not play a role in the erosion of these soils, and the dispersion of these soils is basically a physical phenomenon caused by the loess texture in the study area.Conclusion: The results of the studies indicate that almost all the tests have the ability to detect the dispersion of the soil, the only difference is in expressing the intensity of the dispersion and actually the accuracy of the test. In determining the dispersion potential of soils, the pinhole test better models the actual state of water seepage in the cracks in the soil structure. So, in any case, the results of this test can represent the potential of real soil dispersion in the region. In determining the dispersion potential of soils, the Crumb test in loess soils showed the dispersion potential to be lower than the actual state, and the double hydrometric method had the most agreement with the results of the pinhole test.Keywords: Loess soils, Dispersive soil, Pinhole test, Double hydrometric test.

Introduction: In some soils, special phenomena happen with increases in their moisture content that sometimes inflict major damages on development projects. Dispersive soils are one type of such soils. The physico-chemical properties of the particles in dispersive soils cause them to disperse and separate from each other upon contact with water. If dispersive clays are not accurately identified, they will cause damages and failures. In the Simin Dasht region of Semnan Province, some hydraulic structures have incurred serious damages because they are located on dispersive soils.

Introduction: loess are a special type of silty soil with a porous structure and poor cohesion, and often contain silt with minor amounts of clay to fine sand . These characteristics make loess among the problematic soils in terms of engineering geology. problematic soils are observed in different parts of the world including Australia, Brazil, New Zealand, the United States and many areas of Iran. Some fine-grained soils are structurally unstable, that is, they are easily dispersed and are highly erodible. Hence, presence of such soils in engineering and Agricultural projects can cause great damage and financial loss. One of the most important influencing factors in the vulnerability of loess soils is the dispersion phenomenon. Dispersion or colloidal erosion is a physical-chemical process that often occurs in fine-grained soils containing clay particles. In general, dispersion phenomena occur when the shear stress induced by the flow exceeds the friction among particles, causing surface abrasion. Erosion can extend itself along a drying crack, settlement, hydraulic fracture, or other high permeability channels in a soil mass. Dispersive loess soil easily and quickly separates and disperses from each other in water with low salt concentration without any special mechanical stimulation. Climate and physicochemical characteristics are two important factors in soil dispersive. which affect the degree of soil dispersive. Climate affects soil development by influencing physicochemical characteristics. On the other hand, soil texture, clay content, porosity and Bulk density, pH and solubility of salts in soil are closely related to dispersive. Although, extensive researches carried out to determine the dispersion potential of the soils, affecting factors on dispersion phenomenon and validation of the soil dispersion tests, no comprehensive studies have been performed on The effect of climatic characteristics loess soils in golestan province. Therefore, the aim of this research is to investigate the effect of climate and physicochemical characteristics on soil dispersive.Materials and Methods: This research was focused on loess soils of Golestan province. seven pedons were selected, sampled and described in different parts of the province. Climatic data was prepared and physicochemical and dispersive analyzes were performed on soil samples. The values of pH, electrical conductivity, equivalent calcium carbonate, cation exchange capacity and bulk density were measured. In order to study the degree of divergence, Sherrard's chemical test and pinhole test were performed.Results and Discussion By investigating the amount of rainfall in different regions of the province, it was found that the loess soils of Golestan province are not in the same climatic conditions. The results showed that the climatic and physicochemical characteristics of the soils in interaction with each other had a significant effect on the evolution of the soil and the reduction of divergence in the studied soils. The highest amount of precipitation was in Ramyan and Minodasht region And these two regions had greater depth of soil and heavier texture than other pedons. The results of the pinhole test show these soils with intermadiate dispersion potential. While the results of the chemical test for most of the samples are non dispersive. According to the results obtained from the pinhole test, Minodasht and Sufian pedons with rainfall of 815.8 and 608.9 mm were completely non-divergent, and Hoten pedon with Aridic moisture regime and rainfall of 189.7 mm had the highest dispersion potential. In total, 30% of the horizons showed moderate dispersion. which were mostly in the Aridic moisture regime. The chemical test in this research also confirmed the presence of a small amount of sodium ion in the saturated soil extract, and only three horizons had the potential of chemical divergence based on the SAR level. From the results, it can be analyzed that the soil dispersion in this research is due to the physical nature of soil particles.Conclusion: The review of climatic data and the results of physico-chemical tests showed the existence of direct coordination between the climatic and physico-chemical properties of the soil. So that with the increase of rainfall, the soil formation process increased. This means that in soils with xeric regime and high rainfall, the percentage of clay, organic matter, porosity and water retention in the soil has increased. As a result, the dispersion potential in these soils has decreased. Keywords: Loess soils, Dispersive soil, Physicochemical dispersion, Pinhole test.

Soil dispersion is a phenomenon where soil particles float when they are exposed to water and are carried away by the force of seepage. Various laboratory methods, including double hydrometer, Emerson, and pinhole tests and the Sherard chemical method have been used to evaluate soil dispersion potential. Despite the fact that soil dispersion is caused by its chemical composition, the results obtained from the chemical methods, especially from the Sherard method, do not match the results of the pinhole test. In this study, the role of existing anions in the dispersion potential of clayey soils was studied. Natural soil samples were collected from different regions of Iran and artificial soil samples were created by adding different percentages of sodium chloride, sodium carbonate, sodium sulfate, and sodium polyphosphate to a nondispersive soil. The physical, chemical, and index properties of all samples were determined and the Sherard method and pinhole test were employed to determine the dispersion potential. The results obtained from the tests showed that soil dispersion, which is a physico-chemical phenomenon, was caused by a combination of existing anions and cations in the soil, both in type and quantity. It was also found that the Sherard chemical method did not determine soil dispersion correctly since the role of some anions, especially chloride, was neglected. Among the existing anions in the soil, chloride, as opposed to sodium, acted as a flocculating factor.

Producion of efficient antimicrobial drugs against to common human pathogens is one of the most important challenges in the field of medical microbiology. Continuous screening of clinical isolates and survey of antimicrobial resistance pattern is critical.Today, disk diffusion and dilution methods are known as the common antimicrobial susceptibility testing methods. Disk diffusion method does not render dependable results in determination of antimicrobial susceptibility pattern because this method is semi quantitative. MIC determination by microdilution and macrodilution techniques and recent method “E-Test”, have given interpretable results to researchers. Microdilution and macrodilution methods are also time consuming, expensive and error- prone methods. Whereas E-Test method is one of the means by which we will be able to determine susceptibility pattern of known species in low cost and short time. In this survey, constructing and printing of E-Test, coating of antibiotic on O.H.P film and quality control of constructed E-Tests were performed according to M7 A7 CLSI Standard. In this study quality of required materials for E-Test Production were suitable. Evaluation of constructed strips was performed using standard strain of staphylococcus aureus and reproducibly of results was appreciated.

Contact dermatitis is an inflammatory skin disease due to contact with different substances and caused by two mechanisms: allergy and irritation. Contact dermatitis is a common skin disease and the most common occupational dermatosis. Differentiating between allergic and irritant contact dermatitis is essential in the identification of etiologic factor(s) and hence, its control and prognosis. This differentiation can be done only by patch test. Unfortunately, this simple, safe and useful test is always neglected. We review the basics of patch test, the method of performance, reading and interpretation of its results, possible side effects and results of studies done with patch test in different countries.