Isolation, distribution and evaluation of cytotoxic and antioxidant activity of cultivable actinobacteria from the Oman Sea sediments     

Gozari Mohsen  Bahador Nim  Jassbi Amir Rez  Mortazavi Mohammad Seddiq  Hamzehei Sam  Eftekhar Ebrahim 《海洋学报(英文版)》2019,38(12):84-90

Screening bioactive natural products from bacteria is a determinative step in the drug discovery programs. The present study aim to isolate actinobacteria from the Oman Sea sediments for determining the effects of different culture media and treatments on the yield of the isolation process, and measure the DPPH radical scavenging and Artemia cytotoxic activity of culture extracts of the actinobacterial isolates. A total of 290 actinobacterial isolates were collected from 14 sediment samples. Heat treatment(40.68%) and M_4 medium(29.31%) exhibited the maximum isolation rates of actinobacteria. Streptomyces isolates were dominantly distributed in all of the investigated stations according to 16 S rRNA gene sequencing. The distribution pattern of Streptomyces followed a depth-dependent frequency trend, whereas the members of rare genera including Micromonospora, Nocardia Actinoplanes, Nocardiopsis, Saccharopolyspora and Crossiella were distributed in deeper stations. Approximately,25% of the examined isolates could scavenge 90% of 10~(–4) mol/L DPPH solutions at 1 250 μg/mL final concentration of their ethyl acetate culture extracts. Furthermore, the most potent extracts could scavenge DPPH radicals with IC50 ranges from 356.8 to 566.4 μg/mL. Brine shrimp cytotoxicity tests showed that 38.88% of the examined culture extracts exhibited LC_(50) lower than 1 000 μg/mL against the Artemia cells. Moreover, the most potent culture extracts exhibited LC_(50) range from 335.4 to 534.4 μg/mL. Phylogenetic analysis by 16 S rRNA gene sequence revealed that the OS 005, OS 263 and OS 157 closely related to Streptomyces djakartensis, Streptomyces olivaceus and Nocardiopsis dassonvillei respectively. These results suggested the widespread distribution of the antioxidant and cytotoxic producing actinobacteria in the Oman Sea sediments, which could be considered as promising candidates for the discovery of microbial bioactive compounds.  相似文献   

Assessment of future changes in the maximum temperature at selected stations in Iran based on HADCM3 and CGCM3 models     

Mohsen Abbasnia  Taghi Tavousi  Mahmood Khosravi 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(4):371-377

Identification and assessment of climate change in the next decades with the aim of appropriate environmental planning in order to adapt and mitigate its effects are quite necessary. In this study, maximum temperature changes of Iran were comparatively examined in two future periods (2041-2070 and 2071-2099) and based on the two general circulation model outputs (CGCM3 and HADCM3) and under existing emission scenarios (A2, A1B, B1 and B2). For this purpose, after examining the ability of statistical downscaling method of SDSM in simulation of the observational period (1981-2010), the daily maximum temperature of future decades was downscaled by considering the uncertainty in seven synoptic stations as representatives of climate in Iran. In uncertainty analysis related to model-scenarios, it was found that CGCM3 model under scenario B1 had the best performance about the simulation of future maximum temperature among all of the examined scenario-models. The findings also showed that the maximum temperature at study stations will be increased between 1°C and 2°C in the middle and the end of 21st century. Also this maximum temperature changes is more severe in the HADCM3 model than the CGCM3 model.  相似文献   

Unsteady flow over offshore wind turbine airfoils and aerodynamic loads with computational fluid dynamic simulations     

M. Abbaspour  A. R. Radmanesh  M. R. Soltani 《International Journal of Environmental Science and Technology》2016,13(6):1525-1540

The first notable megawatt class wind turbine, which was the pioneer of improvement in the blade performance in large wind turbines, appeared in Vermont. Nowadays, modern wind turbines are using blades with multi-airfoils at different sections. In this study, in order to indicate the best airfoil profile for the optimum performance in different sections of a blade, five popular airfoils, including S8xx, FFA and AH series, were studied. On the large-scale profile, shear stress transport K–ω model was applied for the simulation of horizontal axis wind turbines for different wind speeds. The aerodynamic simulation was accomplished using computational fluid dynamic method, which in turn is based on the finite volume method, and semi-implicit method for pressure-linked equations algorithm is used for pressure–velocity coupling. The governing equations applied in this simulation are the unsteady Reynolds-averaged Navier–Stokes equations. The aerodynamic coefficients of lift and drag were calculated at different angle of attacks and different wind speeds. The results were validated by EPPLER code, XFOIL and experimental data of the US National Renewable Energy Laboratory. The results showed that S818 profile is the best profile in terms of gaining the highest lift coefficient with the lowest angle of attack at the root of the blades. The findings also indicated that the selected model can predict the exact geometry with a high precision.  相似文献   

Groundwater risk mapping prediction using mathematical modeling and the Monte Carlo technique   总被引：1，自引：0，他引：1  

Fatemeh Jafari  Saman Javadi  Golmar Golmohammadi  Kourosh Mohammadi  Ahmad Khodadadi  Mohsen Mohammadzadeh 《Environmental Earth Sciences》2016,75(6):491

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Drought prediction using co-active neuro-fuzzy inference system,validation, and uncertainty analysis (case study: Birjand,Iran)     

Hadi Memarian  Mohsen Pourreza Bilondi  Majid Rezaei 《Theoretical and Applied Climatology》2016,124(3-4):541-554

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Spatio-temporal analysis of crime by developing a method to detect critical distances for the Knox test   总被引：1，自引：0，他引：1  

Mohsen Kalantari  Bamshad Yaghmaei  Somaye Ghezelbash 《International journal of geographical information science》2016,30(11):2302-2320

The present study examined and compared spatio–temporal interaction of the theft of car parts, shop burglary and motorcycle theft in the central business district (CBD) of the city of Zanjan in Iran. The Knox test was selected to detect spatio–temporal interaction. This test has been criticized as being subjective because the selection of critical distances is arbitrary; thus, a method is proposed to detect critical distances in the Knox test using the mean distance, natural breaks classification of nearest neighbour (NN) distance and Ripley’s k function. Results show obvious differences between the spatio-temporal clusters of the three sets of crimes. They also indicate that changing the spatial cut-offs within a cluster creates different temporal patterns. Of the three criteria for determining critical distances, NN classification based on natural breaks showed more interactions than the other methods.  相似文献   

Modeling the exceptional south Foehn event (Garmij) over the Alborz Mountains during the extreme forest fire of December 2005     

Abbas Mofidi  Iman Soltanzadeh  Yadollah Yousefi  Azar Zarrin  Mohsen Soltani  Jafar Masoompour Samakosh  Ghasem Azizi  Samuel T. K. Miller 《Natural Hazards》2015,75(3):2489-2518

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Evaluation of earthquake mitigation measures to reduce economic and human losses: a case study to residential property owners in the metropolitan area of Shiraz,Iran     

Mehdi Sadeghi  Stefan Hochrainer-Stigler  Mohsen Ghafory-Ashtiany 《Natural Hazards》2015,78(3):1811-1826

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Sedimentological,Geochemical and Hydrogeochemical Studies of Alluvial Fans for Mineral and Environmental Purposes (Case Study of Southwestern Iran)     

Saeid Pourmorad  Harami  Reza Mousavi  Solgi  Ali  Aleali  Mohsen 《Lithology and Mineral Resources》2021,56(1):89-112

Lithology and Mineral Resources - The alluvial-fan sediments play a very important role in mineral reserves and underground water resources, though a comprehensive study on such sediments,...  相似文献   

Thermal instability and the effects of cosmic-ray diffusion     

Mohsen Shadmehri 《Monthly notices of the Royal Astronomical Society》2009,397(3):1521-1527

We study the dynamical effects of cosmic rays (CRs) on thermal instability in the linear regime. CRs and the thermal plasma are treated as two different interacting fluids, in which CRs can diffuse along the magnetic field lines. We show that the growth rate of the magnetothermal condensation mode is reduced because of the existence of CRs, and this stabilizing effect depends on the diffusion coefficient and the ratio of CR pressure to gas pressure. Thus, a slower rate of structure formation via thermal instability is predicted when CRs are considered.  相似文献