Isolation and characterization of two crude oil-degrading yeast strains, Yarrowia lipolytica PG-20 and PG-32, from the Persian Gulf   总被引：1，自引：0，他引：1  

Hassanshahian M  Tebyanian H  Cappello S 《Marine pollution bulletin》2012,64(7):1386-1391

Among six crude oil-degrading yeasts that were isolated from an oil-polluted area in the Persian Gulf, two yeast strains showed high degradation activity of aliphatic hydrocarbons. From an analysis of 18S rRNA sequences and biochemical characteristics, these strains were identified as Yarrowia lipolytica strains PG-20 and PG-32. Gas Chromatography (GC) analysis of the crude oil remaining in the culture medium after 1 week at 30°C showed that the strains PG-20 and PG-32 degraded 68% and 58% of crude oil, respectively. The optimal growth condition and biodegradation of hydrocarbons was in ONR medium with an acidic pH (pH5). These two strains may degrade aliphatic hydrocarbons more efficiently than aromatic hydrocarbons, although strain PG-20 had better degradation than strain PG-32. The two Y. lipolytica strains reduce surface tension when cultured on hydrocarbon substrates (1% v/v). These strains showed a cell surface hydrophobicity higher than 70%. These results suggested that Y. lipolytica strains PG-20 and PG-32 have high crude oil degrading activity due to their high emulsifying activity and cell hydrophobicity. In conclusion, these yeast strains can be useful for the bioremediation process in the Persian Gulf and decreasing oil pollution in this marine ecosystem.  相似文献   

伊朗锡斯坦地区沙漠灾害区划(英文)   总被引：1，自引：1，他引：0  

Seyed Mahmood HOSSEINI  Sahar SADRAFSHARI  Mehdi FAYZOLAHPOUR 《地理学报(英文版)》2012,22(5):885-894

Desertification process as a great problem affects most of the countries in the world.This process has a high rate in arid and semiarid areas.Today,human societies are encountering the desertification phenomenon as a serious problem which causes various irreparable damages to economic and social sectors.In order to assess desertification results in production of different regional models for their application in another region the indices should be re-investigated and adjusted to local conditions.Several models have been developed for desertification evaluation.The present study,attempts to assess quantitatively the desertification process has in an area located at Sistan plain of Iran(Niatak region as a case study) by using Modified MEDALUS method.The obtained results indicated that of the whole studied region(comprising 4819.6 acres),2651.56 acres(55%) are located in medium desertification intensity class,1269.48 acres(26.34%) are positioned in severe desertification intensity class,and 898.54 acres(18.64%) are placed in vary severe desertification intensity class.  相似文献   

Enhanced nonlinear static analysis with the drift pushover procedure for tall buildings     

Farhad Behnamfar  Sayed Mehdi Taherian  Arash Sahraei 《Bulletin of Earthquake Engineering》2016,14(11):3025-3046

In this study a new method for nonlinear static analysis based on the relative displacements of stories is proposed that is able to be implemented in a single stage analysis and considers the effects of an arbitrary number of higher modes. The method is called the extended drift pushover analysis procedure (EDPA). To define the lateral load pattern, values of the relative displacements of stories are calculated using the elastic modal analysis and the modal combination factors introduced. For determining the combination factors, six different approaches are examined. Buildings evaluated in this study consist of four special steel moment-resisting frames with 10–30 stories. Responses including relative displacements of stories, story shear forces and rotation of plastic hinges in each story are calculated using the proposed approaches in addition to modal pushover analysis and nonlinear dynamic time history analyses. The nonlinear dynamic analysis is implemented using ten consistent earthquake records that have been scaled with regard to ASCE7-10. Distribution of response errors of story shears and plastic hinge rotations show that a major part of error corresponds to the second half of the buildings studied. Thus, the mentioned responses are corrected systematically. The final results of this study show that implementing the EDPA procedure using the third approach of this research is able to effectively overcome the limitations of both the traditional and the modal pushover analyses methods and predict the seismic demands of tall buildings with good accuracy.  相似文献   

From Satellite Gradiometry Data to Subcrustal Stress Due to Mantle Convection     

Mehdi Eshagh 《Pure and Applied Geophysics》2014,171(9):2391-2406

Subcrustal stress induced by mantle convection can be determined by the Earth’s gravitational potential. In this study, the spherical harmonic expansion of the simplified Navier–Stokes equation is developed further so satellite gradiometry data (SGD) can be used to determine the subcrustal stress. To do so, we present two methods for producing the stress components or an equivalent function thereof, the so-called S function, from which the stress components can be computed numerically. First, some integral estimators are presented to integrate the SGD and deliver the stress components and/or the S function. Second, integral equations are constructed for inversion of the SGD to the aforementioned quantities. The kernel functions of the integrals of both approaches are plotted and interpreted. The behaviour of the integral kernels is dependent on the signal and noise spectra in the first approach whilst it does not depend on extra information in the second method. It is shown that recovering the stress from the vertical–vertical gradients, using the integral estimators presented, is suitable, but when using the integral equations the vertical–vertical gradients are recommended for recovering the S function and the vertical–horizontal gradients for the stress components. This study is theoretical and numerical results using synthetic or real data are not given.  相似文献   

Assessment of Relationship Between Grouted Values and Calculated Values in the Bazoft Dam Site     

Ahmad Rastegarnia  Abdollah Sohrabibidar  Vahid Bagheri  Mehdi Razifard  Abbas Zolfaghari 《Geotechnical and Geological Engineering》2017,35(4):1299-1310

Seepage through foundation and abutments of a dam can potentially result in a waste of the water stored in dam reservoir, erosion of foundation materials, and development of uplift pressure in dam foundation which, consequently, threatens the long-term stability of the dam. In this study, the grout volume is estimated based on parameters such as joint aperture, the maximum penetration length of the grout, and calculated grout take in Bazoft dam site. Bazoft Dam is a hydroelectric supply and double-curvature arch dam with a height of 211 m located in Chaharmahal and Bakhtiari Province of Iran. The bedrock of Bazoft dam site consists of Asemari Formation (limy marl and marly lime), in the middle and upper parts of left abutment, and Jahrom Formation (limestone and dolomite) in the right abutment, river bed, and lower part of left abutment. The joint apertures were calculated based on the permeability and the joint spacing. Next, the maximum penetration length of the grout and grout volume were calculated. Using a statistical analysis, the relationship of the joint aperture, maximum penetration length, and the calculated grout volume with real grout take was also investigated. The results show that the grout take can be predicted with appropriate accuracy based on the calculated grout volume.  相似文献   

Effect of texture of carbonate soils in South Iran coasts on aggregate crushing     

Mahmoud Fatemiaghda  Habib Shahnazari  Mehdi Talkhablu 《Marine Georesources & Geotechnology》2017,35(7):986-998

Aggregate crushing is a phenomenon occurring in carbonate soils under shear and compressive loads resulting in settlement of the offshore structures such as piers, bridges, waterfronts, wharfs, and oil and gas extraction platform foundations. Therefore, it is of significant importance to address the above-mentioned issue through a comprehensive study. In the present research, the texture of carbonate soil in south Iran coasts and its effect at high hydrostatic pressure (2?MPa) on aggregate crushing was studied. The physical properties of coastal soils, such as the effective grain size, shape index, and angularity were then characterized to investigate their effect on grain crushing grade. The results showed that the effective grain size, shape index, angularity, and calcium carbonate content are the main parameters affecting the crushing of grains and consequently settlement of marine soils. Based on the above parameters, a relationship is proposed to estimate grain crushing in carbonate soils.  相似文献   

Terrestrische Sedimente der Intermontanbecken im Iran     

Dr.-Ing. Mehdi Nadji 《International Journal of Earth Sciences》1974,63(3):897-904

Noteworthy facts about terrestrial deposits which fill the Internal Basins in Iran have been studied mainly in the last decade. Hydrogeological investigations in more than 100 alluvial basins have been most informative for essential knowledge about the structure of and sedimentation in the extensive plains. The thickness of the alluvial deposits ranges in different amount. Its known maximum, above 500 m, is located in the area between Teheran and Karaj. By the example of Varamin Plain it is shown that the sedimentation has an unequivocal dependence on the recent drainage pattern. The trace of“Water veins” is very important for exploration of ground water. The“Veins” are ancient washes filled up with outwashed gravels which are covered later with younger fine grained materials. The occurrence of these highly permeable deposits can be found by means of sedimentological investigations.  相似文献   

Higher-degree reference field in the generalized Stokes-Helmert scheme for geoid computation     

Petr Vaníček  Mehdi Najafi  Zdeněk Martinec  Lars Harrie  Lars E. Sjöberg 《Journal of Geodesy》1995,70(3):176-182

In this paper we formulate two corrections that have to be applied to the higher-degree reference spheroid if one wants to use it in conjunction with the Stokes-Helmert scheme for geoid determination. We show that in a precise geoid determination one has to apply the correction for the residual topographical potential and the correction for the earth ellipticity. Both these corrections may reach several decimetres; we show how their magnitudes vary within Canada and we give their global ranges.  相似文献   

Health risk assessments due to nitrate levels in drinking water in villages of Azadshahr,northeastern Iran     

Mehdi Qasemi  Mansoureh Farhang  Hamed Biglari  Mojtaba Afsharnia  Afsaneh Ojrati  Fatemeh Khani  Mohammad Samiee  Ahmad Zarei 《Environmental Earth Sciences》2018,77(23):782

Groundwater is the main water source used for drinking and cooking purposes globally. Nitrate level in most groundwater resources in arid and semi-arid areas has increased in the past several decades as a result of human activities and natural processes. This may exert a great impact on human health. To learn the contamination circumstances of groundwater nitrate in villages of Azadshahr, Iran and assess its probable risk to the health of adults, children and infants, fifty-eight groundwater samples were collected from wells and springs in 2018. Nitrate concentrations had a wide spatial variability in wells and springs of the studied villages, with values going from 1 up to 51 mg/L. Exceedances of the EPA standard value were limited to two village springs (villages Nili and Narab, with nitrate level of 51 and 46 mg/L, respectively). The hazard quotients (HQ) values for 41% of children and infants were above the safety level (i.e., HQ?>?1), suggesting that groundwater nitrate would have significant health effects on these age groups. Therefore, appropriate control measures and sanitation improvement programs should be put in place to protect the health of the residents in the contaminated villages.  相似文献   

Spatial assessment of the potential of groundwater quality using fuzzy AHP in GIS     

Saeed Azimi  Mehdi Azhdary Moghaddam  Seyed Arman Hashemi Monfared 《Arabian Journal of Geosciences》2018,11(7):142

In this study, fuzzy AHP method is used for extracting the water quality indicators based on the Schuler standard and World Health Organization (WHO) guidelines during a 20-year period. For this purpose, the best fit of the zoning model was performed. Furthermore, by comparing the standard errors, the continuous Raster layer was extracted from the important parameters used in generating the qualitative potential assessment index. The classified layer was generated by integrating continuous layers in the GIS environment and with the use of Python programming. The similarity of the outputs of both methods indicates the presence of large sections of aquifers in the middle and southwestern regions of Iran in the “temporarily drinkable” and “bad” classes. The calculations showed that the majority of aquifers that were located in the “inappropriate” class during the first 10 years fell to less valuable class types. Based on the results of the model, there is a direct correlation between the drop in water resources and the decline in the quality indices. In addition, in the Urmia and Bushehr coastal aquifers, due to excessive water withdrawal and salty water penetration, the quality of the table water is in critical condition. Based on the results of the research, the aquifers in the range of Zagros and Alborz mountains show the least change in water quality. The reason for this is the depth of the aquifer and the ability to recharge it.  相似文献