فهرست مطالب rouhollah heydari

Graphene oxide/polydopamine-polyacrylamide nanocomposite was synthesized by a simple method and  used  as  adsorbent for  dispersive  micro-solid-phase  extraction of phenobarbital  in  plasma samples.  The adsorbent  was  characterized  by  Fourier-transform  infrared  spectroscopy,  X-ray diffraction, scanning electron microscopy–energy dispersive spectroscopy and thermal gravimetric analysis. The  results show  that functionalization of graphene  oxide  by  polymeric  materials  can enhance  the  sorption  properties  and  thermal  stability  of the  prepared  adsorbent.  Influential parameters on  the extraction  efficiency  of Phenobarbital  including  adsorbent  amount,  elution solvent and its volume, sorption and desorption times and pH of sample solution were investigated and optimized. Under the optimized conditions, limits of detection and quantitation values were 1.4 and 5ng/mL, respectively. Relative recovery data for several real samples were obtained within the range of 84.0-98.0% with a relative standard deviation less than 7.2%. The proposed method was successfully applied to quantitative determination of phenobarbital in plasma samples.

In this study, Chemical Oxygen Demand (COD) from a pharmaceutical wastewater (PhW) was reduced by several techniques such as electro-Fenton (EF), photo electro-Fenton (PEF) and activated sludge (AS) processes and the obtained data were compared with each other. The effects of several parameters such as pH, current density, H2O2/Fe2+ molar ratio, volume ratio of H2O2/PhW, reaction time and UVA light were studied on the COD reduction through the EF and PEF processes. The Box-Behnken Design (BBD) under Response Surface Methodology (RSM) was applied to design and then optimize these processes. The optimal conditions for 87% of COD removal through the EF process were at pH of 3.27, current density of 57 mA/cm2, H2O2/Fe2+ molar ratio of 3.5, volume ratio of H2O2/PhW of 1.34 ml/l and reaction time of 56.32 min while the optimal conditions for 91.6% of COD removal through PEF process were at pH of 3.5, current density of 57.5 mA/cm2, H2O2/Fe2+ molar ratio of 3.81, volume ratio of H2O2/PhW of 1.5 ml/l, reaction time of 10.12 min and 6 W UVA light while 77.70% of COD removal was obtained by  the AS process with residence time of 1020 min. According to the kinetic study, the second order reaction (with high R2 data) could properly model the EF and PEF processes.

Simultaneous spectrophotometric determination of some polycyclic aromatic hydrocarbons (PAHs) in wastewater samples after preconcentration by salting-out assisted liquid-liquid extraction was achieved using a doolittle multivariate calibration algorithm (DMCA). The DMCA was applied by lower and upper (LU) triangular matrix decomposition which is efficient, powerful and easily. Results were shown that DMCA has advantages such as, simplicity, rapidness, avoiding matrix inverting and reducing the orders of matrices. The influence of various parameters, such as extraction solvent and volume, type and amount of salt, vortex time and sample pH were studied and optimized. The net analyte signal (NAS) method was used for calculating figures of merit. Linear range (LR) of calibration graphs for naphthalene, anthracene and pyrene were between 0.20 - 2.00, 0.10 - 1.50 and 0.07 -1.00 µg mL-1, respectively. The root mean square errors of prediction (RMSEP) for naphthalene, anthracene and pyrene using DMCA model were 0.0367, 0.0331 and 0.0305, respectively.

The indiscriminate consumption of antibiotics and their discharge into the environment have created serious complications. Therefore, it is necessary to remove these contaminants from the aquatic environment. The antibiotic Metronidazole is a contaminant that should be eliminated from the environment. The aim of this study was to evaluate the use of the Electro-Fenton advanced oxidation process for the removal of metronidazole from aqueous solution.
This research method was experimental and bench scale. The influence of factors such as solution pH, reaction time, the initial concentration of metronidazole, electric current, and hydrogen peroxide concentration on the removal efficiency were investigated.
In this study, the dose of hydrogen peroxide, electric current, and reaction time had a positive effect on metronidazole removal efficiency, while the initial concentration of metronidazole had a negative effect. The optimal values of variable for the removal of more than 99% metronidazole were: pH =7, current 30v, reaction time 40min, dose of hydrogen peroxide 0.02 mol/l and the initial concentration of metronidazole 10mg/l.
The Electro-Fenton process can effectively remove metronidazole from aquatic solutions in environmentally convenient conditions. This process can be used as an efficient method for removing other persistent pollutants from the environment.

The kind of population, climate and density have a significant influence on the various properties of the Milk Thistle. Therefore, the impact of two temperate and cold climate on the four native populations collected from Shush, Poldoktar, Khorramabad and Aleshtar and a cultivar were evaluated as a randomized complete block design in a few years and places. As Well as an experimental was performed in the form of Split plot includes three different densities of 6, 8 and 10 plants/m2 as subplots and populations of Milk Thistle as main plots for two years from 2014-2015. The results showed that the climate had significant impact on traits such as plant height, grain yield and Silybin. Results of the interaction effects showed that The maximum amount of Silymarin (21 mg.g) and Silybin (4.2 mg.g) was obtained in native population of Aleshtar and in the cold region. Also the highest of plant height, grain and biological yield was obtained at density of 8 plants/m2 but the density did not affect on the amount of Silymarin.

In this study, ultrasonic-assisted matrix solid-phase dispersion (UA-MSPD) as a new sample preparation method for natural product analysis was developed. Influential parameters of the UA-MSPD method was optimized using oleuropein content of olive leaves as a model analyte. Main parameters of the proposed technique such as ultrasonic time, amplitude and pulse, sorbent material, the ratio of sample to sorbent material, elution solvent and its volume have been fully evaluated and optimized. In the proposed method several steps in classical MSPD including, transfer of sample and sorbent mixture to cartridge, packing and elution under vacuum conditions were removed. Also, ultrasound waves were applied to the sample and sorbent mixture in elution step for effective analyte desorption. Oleuropein was successfully extracted by silica gel and acetone as the sorbent and elution solvent, respectively. The calibration curve shows good linearity (R2=0.9979) and precision (RSD < 6.8) in the concentration range of 0.1-200 μg/mL for oleuropein. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.03 and 0.1 μg/mL, respectively. The recovery values were in the range of 90.2-96.7% with RSD values ranging from 5.5-7.2%.

Cloud point extraction (CPE) as a rapid, simple and efficient method coupled with high performance liquid chromatography (HPLC) was used for sample preparation and subsequent determination of carbazole, trinitrocarbazole (TrNC) and tetra nitro carbazole (TNC) in water samples. Some effective parameters on extraction, such as volume of Triton X-100, extraction time, extraction temperature, ionic strength and centrifuging time were studied and optimized. Under the optimum conditions, recoveries of analytes were in the range of 98.0–102.0 . The calibration curve was linear in the range of 0.08 to 15.0 μg mL−1 for TNC, 0.06 to 15.2 μg mL−1 for TrNC, and 0.08–21.0 μg mL−1 for carbazole. Limit of detection (LOD) and limit of quantification (LOQ) were in the range of 0.009 -0.01 and 0.06-0.08μg mL−1, respectively. The relative standard deviations (RSDs) were in the range of 4.0- 6.2 %. The obtained results show that CPE with a high performance liquid chromatography (HPLC) is a sensitive and simple method for the determination of carbazole, TrNC and TNC in water samples.

Global temperature has increased about 0. 74°C over the last century (IPCC، 2007، 30). In recent studies، the potential of increase in heat waves، heavy precipitation، cold winter، summer storms and drought event due to climate change noticed (Zhang،2005،11). On the other hand، it is believed that climate change will affect most aspects of weather and climate، especially precipitation and temperature extreme events (Radinovi and Curi، 2009، 200; Lehner et al.، 2006، 293). Therefore، the socio-economic effects of extremes (Ryoo et al.، 2004، 145)، require more attention to such studies. Assessment of the temperature extremes changes is done in many region of the world in the last century (Mudelsee et al. 2003; New et al. 2001; Moberg and Jones 2005; Klein Tank and K¨onnen 2003; Alexander et al. 2006). The socio - economic effects of extremes in arid and semi arid regions like Iran due to very vulnerable and fragile climates are more and their sudden changes may be followed by the devastating events. Spatial and temporal variability of climate in Iran is one of its inherent characteristics and devastative socio-economic effects of climatic disasters such as floods and droughts have been high in recent years (Nazemosadat and Cordery 2000، 59; Barlow et al. 2002، 697; Nazemosadat and Ghasemi 2004، 4016). Studies such as Rasouli (2004)، about spatial analysis of cold winds in the Southwestern of Iran and Kaviani and his colleagues (2004)، the effective temperatures in the country، show the variability and instability of climate in Iran. Consequences of global warming in Iran include increased frequency of extreme events، especially in cold and heat waves، long time severe droughts and torrential rain (Rahimzadeh et al. 2009، 342). Numerous studies in recent years، has been investigated the average temperature and precipitation variability in Iran (Alijani 1997; Jahadi Toroghi 2000; Rasooli 2002; Rahimzadeh and Asgari 2003; Rahimzadeh and Asgari 2005; Pedram et al. 2005; Asadi and Heydari 2011). Furthermore، Rahimzadeh and her colleagues (2009) were considered the temperature and precipitation extreme variability in Iran and Taghavi، and Mohammadi (2007)، stated that the frequency of warm and cold events، respectively، has been associated with decreases and increases. Moreover، kari (2010)، has confirmed significant changes in heat waves and cold periods in Tehran. The purpose of this study provides a more detailed analysis about the spatial and temporal distribution of the temperature extremes in Iran.