فهرست مطالب s mortazavi

Mine exploitation has led to the rangeland's destruction. In this study, the phytoremediation of Pb-contaminated soils by Chrysypogon zizanioides was investigated in the soil around the lead mine of Lashkar region, located in Malayer county. In the initial measurement, the amount of soil Pb contamination in the rangeland was estimated to be 600 milligrams per kilogram of dry soil. By evaluating the environmental effects of lead in the region, the coefficients of geoaccumulation index, pollution degree, and potential ecological risk were observed in the infinite to very high range. The research was conducted in a completely randomized design with 4 Pb pollution levels (0, 300, 600, and 1600 mg/kg) in 4 replications in the greenhouse of Malayer University for 130 days. At the end of the period, lead concentration in soil, root, shoot, BCF bioaccumulation index, TF transfer coefficient, shoot, and root productivity in vetiver plants were measured. The results showed the increasing effect of soil Pb concentration on the amount of root and shoot Pb concentrations. At the level of 1600 mg/kg contamination, the Pb concentration in the shoot and root reached 242.94 and 242.02 mg/kg, respectively. At most levels of contamination except the level of 1600 mg/kg, the BCF indicators in the root and shoot and the TF coefficient were less than one. TF <1 indicates the lack of high concentration of Pb in harvesting organs and the health of the aerial production. So, vetiver is recommended for the rangeland reclamation in the study area.

Deviant behaviors are instances of unethical behaviors in organizations having an adverse effect on their productivity. The current research was accomplished to explain the relationship between job embeddedness and unethical behavior of cyberloafing among the employees of a public university.

In the framework of descriptive-correlational research aiming at creating applied knowledge in the subject area, a sample of 500 administrative staff who had access to the organizational Internet was surveyed by conducting convenience sampling. And then, sampling adequacy was established given the test power and the number of model’s parameters and coefficients. Field data were gathered by adopting pre-made questionnaires existed in the valid studies after verifying their validity and reliability. Research hypotheses were tested by conducting variance-based structural equation modeling in Smart-PLS software.

According to research results, the variable of job embeddedness has an increasing effect on employees’ cyberloafing behaviors. In addition, job satisfaction decreases the effect of job embeddedness on cyberloafing to a great extent. It should be noted that although job satisfaction makes this relationship close to zero, it does not reverse it. In general, and considering the moderation slope, the amount of exerting the cyberloafing behaviors is almost zero for highly embedded employees who are satisfied with their jobs.

The quality of the relationship between job embeddedness and cyberloafing depends on employees’ attitude towards the job and their perception of job conditions, and thus, job satisfaction can dramatically reduce the effect of job embeddedness on cyberloafing.

Conventional wastewater treatment methods usually cannot meet the standards required by environmental organizations. Therefore, in this study, the efficiency of advanced oxidation methods using persulfate by various activators of hydrogen peroxide, UV, and ozone in the tertiary treatment of municipal wastewater was investigated. Also, the effects of contact time, solution pH, and the molar ratio of oxidants on the color removal were evaluated. The results showed that the highest color removal was obtained in H2O2/S2O82- with a molar ratio of 1.06 to 1 for three processes of H2O2/S2O82-, UV/H2O2/S2O82- and O3/H2O2/S2O82- in solution pH of 9. A comparison of different systems showed the highest color removal efficiency followed the order of O3/H2O2/S2O82- >UV/H2O2/S2O82- >H2O2/S2O82-. The results showed that activating agents and persulfate have a significant effect on the removal of color in wastewater treatment. Therefore, tertiary wastewater treatment by these processes can effectively reuse wastewater in agriculture and aquaculture.

HIFU technology is a non-invasive treatment method based on the conversion of acoustic energy into thermal energy focused on the target area. In this study, the effect of radiation cross- section on heat distribution in the target tissue is investigated. To investigate the effect of radiation cross- section, in this study, finite element method and COMSOL simulation software were used in the linear emission mode of ultrasonic waves. At a maximum input sound intensity of 10 W/cm2, the pressure wave equation was solved by considering thermo-viscous fluid at two cross- sections of 1.5 and 0.8 cm2. Based on the Pennes heat transfer equation, the heat field distribution in skin tissue, subcutaneous fat, and muscle was calculated. To validate the simulation results, the correlation between the results of the mathematical model the experimental method with a 95% confidence level (p<0.05) was evaluated. At an input sound intensity of 10 W/ cm2 and at a focal length of 4.5 mm from the skin surface, with an increase in cross- section from 0.8 to 1.5 cm2, the maximum sound pressure from 8.6 to 20.9 MPa and the maximum temperature from 60 to 139 °C. The results showed that the sound pressure distribution and the thermal dose of the target tissue depended on the cross-sectional area of the sound transducers. It is concluded that in order to achieve the selected treatment protocol, the treatment plan should be simulated based on radiation input and physical characteristics of the tissue.

Four heavy metals were measured in forty-nine topsoil samples collected fromagricultural areas in Siakh-Darengoun, Iran. The goals were to investigate soil spatialdistribution patterns of metals; their potential ecological risk; and sources. The Hakansonpotential ecological risk index and index of geo-accumulation (Igeo) were used forevaluating the condition of soil heavy metal enrichment and the extent of potentialecological risk. Results demonstrated that the mean concentrations in the agricultural soilswere 2.23 mg/kg for Cd, 5.3 mg/kg for Cu, 38.002 mg/kg for Pb, and 13.84 mg/kg for Zn.The average concentrations of Cd and Pb in the agricultural soils were higher than averageworldwide soils and for Cu and Zn, values were lower than average worldwide soils. Thespatial mapping of the distribution of heavy metals produced by kriging interpolationshowed similar patterns for all heavy metals, and higher concentrations of all heavy metalswere observed in the western and southern parts of the study area. Our findingsdemonstrated that in the Siakh-Darengoun plain, natural sources affect the levels of Cu andZn, however, anthropogenic sources such as chemical fertilizers, especially phosphatefertilizers could be the major sources of Cd and Pb. Hossain Abad agro industry in the westof the study area can be considered as one of the most important heavy metal sources. Thegeo-accumulation index classified Cu and Zn into no pollution levels, Cd and Pb intounpolluted to moderately polluted level. Cd produced serious ecological risk in agriculturalsoils and was the main pollutant, while the Cu, Pb and Zn had low ecological risk.Comprehensive potential ecological risk indexes of all metals showed that the soils in SiakhDarengoun were suffering from high level of ecological risk.

The current study investigated the concentration of Cu, Pb, Zn, Cd, Ni, and Cr in shell and soft tissue of Saccostrea cucullata, water, and sediments of seven stations in Qeshm Island of Persian Gulf.

The samples were digested by a combination of nitric acid and perchloric acid and the concentration of elements was measured by atomic absorption spectroscopy.

The results indicated that the concentrations of Cu and Zn in all samples, Ni in the sediment and Cd in oyster were the highest bio-water accumulation factor were significantly higher than those of bio-sediment accumulation factor. Also, these factors in the soft tissue were higher than in the shell. Furthermore, the macro-concentrators of soft tissue were Cd, Cu, and Zn, while the macro-concentrator of shell was Cd.

The shell can be an appropriate monitoring tool for evaluating Cu and Zn in water and Cu in sediments. Also, the soft tissue can be practical for monitoring Cu and Zn in sediments.

Today, the presence and increase of particulate matter is one of the serious factors that threaten human health. In the meantime, trees can accumulate airborne particles by their foliage. In this study, the accumulating ability of various PM by the leaf of some tree and shrub species was evaluated in Isfahan. 12 species of trees and shrubs were selected at 8 locations in Isfahan and the total PM, PM10, PM2.5 and PM0.2 were measured using water and chloroform washing methods by paper filters 91, 42 μm, and Polytetra Fluorethylene filters and digital balance. The results showed that the highest and lowest mean total accumulation of total particulate matter was related to Morus nigra and Salix alba, that were 190.23 ± 23.5 and 11.9 ± 4.42 μg/cm2. In addition, the trend of accumulation of total PM on the leaf surface from the highest to the lowest was: Morus nigra> Platanus orientalis> Ulmus umbraculifera> Morus alba> Acer negundo> Ailanthus altissima> Fraxinus excelsior > Nerium oleander >Robinia pseudoacacia> Cercis siliquastrum> Nerium oleander > Euonymus japonicas> Salix alba and in epicuticular Waxes, Morus nigra> Ulmus umbraculifera > Platanus orientalis > Morus alba> Ailanthus altissima> Acer negundo > Robinia pseudoacacia>Cercis siliquastrum> Fraxinus excelsior > Nerium oleander > Euonymus japonicas> Salix alba. The results indicated that the ability of different tree species to absorb PM depended on the morphological, physiological and ecological characteristics of the leaf. Finally, among the different species the Morus nigra had the highest ability to capture various PM.

Considering the toxicity, health and ecological hazards of heavy metals in the environment and the impact on organisms, it looks essential to measure and evaluate their concentrations at the various levels in indigineous ecological strctures. The present study evaluated the concentration of Lead, Nickel, Copper and Zinc and their ecological risk assessment in surface sediments of Sezar River in Lorestan province. 16 stations along the Sezar River were selected for sampling. After preparation and acid digestion of the samples, the concentrations of these metals were determined by Atomic absorbtion. The average total concentration of the detected metals Ni, Zn, Cu and Pb in the sediment was 71.84 > 40.56> 7.75 > 5.61 mg/kg, respectively. In addition, the evaluation of the Potential acute toxicity, ecological risk, and Pollution Load Index represented a low pollution in the sediments. The environmental risk of the metals in the sediment was evaluated as: Ni> Pb> Cu> Zn. The findings showed that among metals, the contamination factor and modified hazard quotient (mHQ) for nickel was moderate and in the mediun to severe pollution level to the contamination, respectively. According to the results, it can be concluded that Potential acute toxicity, pollution and ecological risk in the region for investigated metals were low. However, a rapid expansion of various human activities in the area and the pollution of nickel in the river along with the probability of its biological effects require continuous monitoring of the river in order to assess the health risk and its ecological risk.

Marine sediments are the most important component of monitoring the health of aquatic ecosystems. The present study uses sediment quality indices to determine the contamination status in Qeshm ecosystems and to evaluate the toxicity of the elements studied for its organisms. Sampling of surface sediments of seven stations was carried out on Qeshm coastal areas. The samples were digested by a combination of nitric acid and perchloric acid, and the concentration of metals was measured by atomic absorption spectrometry. The results of modified Hazard Quotient indicated a high pollution rate for copper and nickel metals in most stations, which was consistent with the results of the Potential Contamination Index in relation to nickel metal. Additionally, the results of the Potential Contamination Index and Contamination Factor agreed with the amount of lead element. According to the results, the pollution index of Hamoon Lake and Zakeri pier was highly contaminated and Modified Pollution Index demonstrated a contamination in Romacha, Hamoon Lake, Zakeri pier and Nazes areas. The enrichment factor associated with contamination regarding most of the heavy metals confirmed the indices used to evaluate the comtamination in the study area. Due to the higher concentrations of the heavy metals in the sediments than that of the quality guidelines, the high toxicity of sediments for the aquatic ecosystems was confirmed. The Romachah, Hamoon, Zakeri stations showed higher pollution levels and sever toxicity for aquatic life. Copper, nickel and in some cases lead, were the main heavy metals that contaminated the sediments in the region.

X-band microwave with 8-12.5 frequency range has various applications such as air control traffic, navy communication and etc. Uncontrolled exposure with microwave can lead to adverse effect on workers. Application of the shielding is superior control for prevention of microwave exposure.The aim of this study is production a new electromagnetic shielding for exposure control of X-band frequency by nano nickel oxide and epoxy resin.

Nanocomposites prepared by epoxy resin and nano nickel oxide (7wt %) with 2, 4 and 6 mm thicknesses. Nanoparticles characterized by XRD and FESEM. Shielding effectiveness measured with vector network analyzer.

The Average of shielding effectiveness for three thicknesses were 2.68, 5.09 and 5.35 dB respectively that were equivalent to 45.98, 69.01 and 70.87 attenuation percentage. Maximum attenuation (8.96 dB or 87.29 attenuation percentage) obtained by the nanocomposite with 6mm thickness at 8.51 GHz frequency. The Average of shielding effectiveness increased with increasing the thickness.

these nanocomposites could be used as appropriate shielding for exposure control of X-band frequency in workplace. Both Epoxy and nanocomposite with 6mm thicknesses are useful in specific frequency such as 8.52 and 8.51 GHz. However, According to economical and technical issues, nanocomposite with 4mm thickness is appropriate shield in this study. In according to required attenuation and economical benefit, attenuation matrix can be used for selecting the appropriate electromagnetic shield.

Harmful algal blooms resulting in red discoloration of coastal waters in the Persian Gulf, Iran were first observed in January 2007. The species responsible for the bloom, which was identified as Cochlodinium polykrikoides, coincided with massive aquatic organisms’ mortalities in the Persian Gulf. In order to provide optimum growth and bloom forming, C. polykrikoides cells were sampled during the bloom conditions in the coastal waters of Persian Gulf. After adaptation in filtered seawater, they isolated by positive phototropism characteristic of this species to light. They were grown in modified media culture at different salinity (30, 32 and 35ppt), temperature (20, 23, 26 and 28ºC) and intensity (35, 70 and 90 μmol m-2s-1). The results of the present study clearly showed that the highest alga biomass and growth rate was obtained following culture under the 32ppt salinity, 26°C temperature, and under a 12h light:12h dark photoperiod regime at a light intensity of 90μmol m-2s-1 provided by cool white fluorescent tubes. Maximum cell density and growth rate of C. polykrikoides in a 60 liter tank for 20 days reached to 32×106 cell L−1 and 0.28 day-1, respectively. However, the mean obtained cell density of C. polykrikoides in temperature regimes 20, 23, 26 and 28ºC (under salinity of 32ppt, and 90μmol m-2s-1 irradiance) were 2730, 9360, 28240 and 18080 cell ml-1, respectively. A two-way ANOVA indicated significant effects of temperature on the growth rate of C. polykrikoides followed by salinity, and then the interaction between temperature and salinity.

In this paper automatic generation control (AGC) of three and five unequal-areas interconnected thermal systems with reheat turbine and generation rate constraints of 3% has been investigated. New fuzzy logic controller for AGC in multi area thermal system is suggested. Fuzzy logic controller is optimized by evolutionary computation Genetic Algorithm (GA). A comparison dynamic response of systems reveals that the dynamic performance of suggested fuzzy controller is superior to conventional controllers. Sensitivity analyses reveals robustness of the fuzzy logic PD controller (FLPD) to wide changes in the system parameters (Inertia constant H, Reheater time constant Tr and Reheater coefficient Kr).