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Kabiri K.,Iranian National Institute for Oceanography
Earth Science Informatics | Year: 2017

The improvement in the capabilities of Landsat-8 imagery to retrieve bathymetric information in shallow coastal waters was examined. Landsat-8 images have an additional band named coastal/aerosol, Band 1: 435–451 nm in comparison with former generation of Landsat imagery. The selected Landsat-8 operational land image (OLI) was of Chabahar Bay, located in the southern part of Iran (acquired on February 22, 2014 in calm weather and relatively low turbidity). Accurate and high resolution bathymetric data from the study area, produced by field surveys using a single beam echo-sounder, were selected for calibrating the models and validating the results. Three methods, including traditional linear and ratio transform techniques, as well as a novel proposed integrated method, were used to determine depth values. All possible combinations of the three bands [coastal/aerosol (CB), blue (B), and green (G)] have been considered (11 options) using the traditional linear and ratio transform techniques, together with five model options for the integrated method. The accuracy of each model was assessed by comparing the determined bathymetric information with field measured values. The standard error of the estimates, correlation coefficients (R2) for both calibration and validation points, and root mean square errors (RMSE) were calculated for all cases. When compared with the ratio transform method, the method employing linear transformation with a combination of CB, B, and G bands yielded more accurate results (standard error = 1.712 m, R2 calibration = 0.594, R2 validation = 0.551, and RMSE =1.80 m). Adding the CB band to the ratio transform methodology also dramatically increased the accuracy of the estimated depths, whereas this increment was not statistically significant when using the linear transform methodology. The integrated transform method in form of Depth = b0 + b1XCB + b2XB + b5ln(RCB)/ln(RG) + b6ln(RB)/ln(RG) yielded the highest accuracy (standard error = 1.634 m, R2 calibration = 0.634, R2 validation = 0.595, and RMSE = 1.71 m), where Ri (i = CB, B, or G) refers to atmospherically corrected reflectance values in the ith band [Xi = ln(Ri-Rdeep water)]. © 2017 Springer-Verlag Berlin Heidelberg

Kamranzad B.,Iran University of Science and Technology | Etemad-Shahidi A.,Griffith University | Chegini V.,Iranian National Institute for Oceanography
Ocean Engineering | Year: 2013

Since wave energy has the highest marine energy density in the coastal areas, assessment of its potential is of great importance. Furthermore, long term variation of wave power must be studied to ensure the availability of stable wave energy. In this paper, wave energy potential is assessed along the southern coasts of Iran, the Persian Gulf. For this purpose, SWAN numerical model and ECMWF wind fields were used to produce the time series of wave characteristics over 25 years from 1984 till 2008. Moreover, three points in the western, central and eastern parts of the Persian Gulf were selected and the time series of energy extracted from the modeled waves were evaluated at these points. The results show that there are both seasonal and decadal variations in the wave energy trends in all considered points due to the climate variability. There was a reduction in wave power values from 1990 to 2000 in comparison with the previous and following years. Comparison of wind speed and corresponding wave power variations indicates that a small variation in the wind speed can cause a large variation in the wave power. The seasonal oscillations lead to variation of the wave power from the lowest value in summer to the highest value in winter in all considered stations. In addition, the seasonal trend of wave power changed during the decadal variation of wave power. Directional variations of wave power were also assessed during the decadal variations and the results showed that the dominant direction of wave propagation changed in the period of 1990 to 2000 especially in the western station. © 2013 Elsevier Ltd.

Mehdinia A.,Iranian National Institute for Oceanography | Khani H.,University of Tehran | Mozaffari S.,University of Tehran
Microchimica Acta | Year: 2014

We have prepared a fiber for solid-phase microextraction of organochlorine pesticides. A graphene-polyaniline composite was electrochemically deposited on a platinum fiber by exploiting the unique properties of polyaniline and graphene. The modified fiber displays thermal stability up to 320 °C and can be used more than 70 times. It possesses high extraction efficiency due to the high specific surface of graphene. The Pt fiber was used for the extraction and subsequent GC determination of the pesticides heptachlor, aldrin, endrin and p,p'-DDT in aqueous samples. The effects of extraction time, extraction temperature, stirring rate, salinity and headspace volume were optimized. Calibration plots are linear (with an R2 of 0.990) in the 0.2 to 250 μg L-1 concentration range, and the limits of detection are below 11 ng L-1 (at an S/N of 3). The relative standard deviations for three replicate measurements with a single fiber were <11.0 %. The recovery of the pesticides from spiked seawater samples ranged from 81 % to 112 %. © 2013 Springer-Verlag Wien.

Aziz-Zanjani M.O.,K. N. Toosi University of Technology | Mehdinia A.,Iranian National Institute for Oceanography
Microchimica Acta | Year: 2014

Introduced in the 1990s, solid-phase microextraction (SPME) has found numerous applications. This is due to the solventless nature of SPME and the large variety of sorbents and coatings available. Highly diverse procedures have been applied to coat supports such as fused silica fibers or metal wires with sorbents in order to enhance capability, selectivity and robustness of SPME. Lately, research also is directed towards more simple methods for deposition of different types of coatings. Several of these methods have resulted in better stability and higher effective surface areas of the coatings. This review (with 128 references) covers the state of the art in methods for coating materials for use in SPME. It is divided into the following sections: (a) Dip methods and physical agglutination methods, (b) sol-gel technology, (c) chemical grafting, (d) electrochemical methods for coating (such as electrodeposition, anodizing and electrophoretic deposition), (e) electrospinning, (f) liquidphase deposition, and (g) hydrothermal methods. A final section covers conclusions and future trends. [Figure not available: see fulltext.] © 2014 Springer-Verlag Wien.

Mehdinia A.,Iranian National Institute for Oceanography | Ziaei E.,K. N. Toosi University of Technology | Jabbari A.,K. N. Toosi University of Technology
Electrochimica Acta | Year: 2014

Nanocomposit of multi-walled carbon nanotubes and tin oxide (MWCNTs/SnO2) was used as an anode material in Microbial fuel cells (MFCs). The anode was constructed by coating of the nanocomposits on the glassy carbon electrode (GCE). The MWCNTs-SnO2/GCE showed the highest electrochemical performance as compared to MWCNT/GCE and bare GCE anodes. MWCNTs-SnO2/GCE, MWCNT/GCE and bare GCE anodes showed maximum power densities of 1421 mWm-2, 699 mW m-2 and 457 mW m -2, respectively. The electrodes were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The electrochemical properties of the MFC have been investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). High conductivity and large unique surface area extremely enhanced the charge transfer efficiency and the growth of bacterial biofilm on the electrode surface in MFC. Comparison of the power density of the proposed MFC with the other one in the literature showed that the MWCNTs/SnO2 nanocomposit was a desirable anode material for the MFCs. © 2014 Elsevier Ltd.

Mehdinia A.,Iranian National Institute for Oceanography | Roohi F.,K. N. Toosi University of Technology | Jabbari A.,K. N. Toosi University of Technology
Journal of Chromatography A | Year: 2011

A new Fe 3O 4/polyaniline nanoparticle (PANI) material has been successfully developed as magnetic solid-phase extraction sorbent in dispersion mode for the determination of methylmercury (MeHg) in aqueous samples, via quantification by gas chromatography/mass spectrometry (GC-MS). The resultant core-shell magnetic solid-phase extraction nanoparticle (MSPE-NP) sorbent was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and Fourier transform-infrared (FTIR) spectroscopy. Fe 3O 4/PANI composites showed fibrous structure with diameters between 50 and 100nm for fibers. The MSPE-NP process involved the dispersion of the Fe 3O 4/PANI nanoparticles in water samples with sonication, followed by magnetic aided retrieval of the sorbent and then, solvent (hexane) desorption of extracted MeHg for GC-MS analysis. The extraction, derivatization and adsorption conditions were optimized by selecting the appropriate extraction parameters including the amount of sorbent, extraction time, derivatizing reagent volume and extraction solvent. The calibration graph was linear in the concentration range of 0.5-300ngmL -1 (R 2>0.993) with detection limit of 0.1ngmL -1 (n=3), while the repeatability was 4.1% (n=5). Enrichment factor was obtained as 91. Seawater sample was analyzed as real sample and good recoveries (>98%) were obtained at different spiked values. © 2011 Elsevier B.V.

Mehdinia A.,Iranian National Institute for Oceanography | Aziz-Zanjani M.O.,K. N. Toosi University of Technology
TrAC - Trends in Analytical Chemistry | Year: 2013

Since the introduction of solid-phase microextraction (SPME) in the 1990s, different types of coating have shown their crucial role in extraction efficiency. In the past decade, unique properties of nanostructured materials (e.g., large surface area, and remarkable thermal, mechanical and chemical stability) led to their application as desirable coatings in SPME. The current review classifies nanomaterial-based SPME coatings as based on carbon, polymer, silica or metal nanoparticles. It also briefly discusses new developments and methods in preparing nanomaterial-based SPME coatings. © 2012 Elsevier Ltd.

Mehdinia A.,Iranian National Institute for Oceanography | Aziz-Zanjani M.O.,K. N. Toosi University of Technology | Ahmadifar M.,K. N. Toosi University of Technology | Jabbari A.,K. N. Toosi University of Technology
Biosensors and Bioelectronics | Year: 2013

Molecular imprinting is an attractive technique for preparing mimics of natural and biological receptors. Nevertheless, molecular imprinting for aqueous systems remains a challenge due to the hydrogen bonding between templates and functional monomers destroyed in the bulk water. The hydrogen bonding between templates and monomers are the most crucial factor governing recognition, particularly in non-covalent molecularly imprinted polymers. Using mesoporous materials for molecular imprinting is an effective approach to overcome this barrier and to remove the limitations of the traditional molecularly imprinted polymers which include incomplete template removal, small binding capacity, slow mass transfer, and irregular materials shape. Here, SBA-15 was used as a mesoporous silica material for synthesis of molecularly imprinted polypyrrole. The pyrrole monomers and template molecules were immobilized onto the SBA-15 hexagonal channels, and then polymerization occurred. The resulting nanocomposites were characterized by Fourier transform infrared (FT-IR) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. In batch rebinding tests, the imprinted nanocomposites reached saturated adsorption within 100min and exhibited significant specific recognition toward the ascorbic acid (AA) with high adsorption capacity (83.7mgg-1). To further illustrate the recognition property of the imprinted nanocomposites, binary competitive and non-competitive adsorption experiments were performed with ascorbic acid, dopamine, paracetamol and epinephrine. The imprinting factors for these compounds in non-competitive adsorption experiments were 3.2, 1.5, 1.4 and 1.3, respectively. The results showed that the imprinted nanocomposites exhibited significant adsorption selectivity for the ascorbic acid against the related compounds. © 2012 Elsevier B.V..

Aziz-Zanjani M.O.,K. N. Toosi University of Technology | Mehdinia A.,Iranian National Institute for Oceanography
Analytica Chimica Acta | Year: 2013

During the last decade, electrochemically prepared coatings have gained widespread acceptance for solid-phase microextraction (SPME) applications. The current review classified these coatings as electropolymerized conductive polymers (CPs), electrodeposited metal oxides, electrophoretically deposited carbon nanotubes (CNTs) and anodized metals. These electrochemical methods resulted in easily controlled and reproducible SPME coatings with inherent characteristics such as biocompatibility, thermal stability and porous structure. The objective of this review is to provide a concise overview of recent developments in the electrochemically prepared SPME coatings and their analytical applications. © 2013 Elsevier B.V.

Mehdinia A.,Iranian National Institute for Oceanography | Aziz-Zanjani M.O.,K. N. Toosi University of Technology
TrAC - Trends in Analytical Chemistry | Year: 2013

Since its introduction in 1990s, different configurations of solid-phase microextraction (SPME) have been evaluated for different applications, and can be classified into the static and dynamic techniques. The current review briefly discusses the development of the techniques applied to reduce extraction time and/or to enhance extraction efficiency. It is also reviews selective microextraction techniques, such as molecularly-imprinted polymer, immunoaffinity, restricted access material and aptamer sol-gel SPME. © 2013 Elsevier Ltd.

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