Antibiotics and malachite green residues in farmed rainbow trout (Oncorhynchus mykiss) from the Iranian markets: A risk assessment

Antibiotic and malachite green residues in farmed rainbow trout muscles were determined by high-performance liquid chromatography for a food risk assessment. The surveillance was carried out on total of 120 rainbow trout fillets, all fishes were randomly sampled from 20 fish markets of Iran. All antibiotics were detected in the range of 0.42–1.20 μg/g for Oxytetracycline, 0.02–0.34 μg/g for Enrofloxacin, 0.21–2.61 μg/g for Florfenicol, and finally 0.02–0.89 μg/g for Malachite green. Our results showed that 99 (82.5%), 36 (30%), 56 (46.6%), and 70 (58.4%) samples contained detectable residues of Oxytetracycline, Enrofloxacin, and Florfenicol antibiotics, and Malachite green, respectively. Our results showed that fish farmers use these drugs in large scale. Further investigations are needed to prevent: the foodborne risk to consumers, the possible environmental contamination, and the antimicrobial resistances.     

Three-dimensional finite difference analysis of shallow sprayed concrete tunnels crossing a reverse fault or a normal fault: A parametric study

Urban tunnels crossing faults are always at the risk of severe damages. In this paper, the effects of a reverse and a normal fault movement on a transversely crossing shallow shotcreted tunnel are investigated by 3D finite difference analysis. After verifying the accuracy of the numerical simulation predictions with the centrifuge physical model results, a parametric study is then conducted. That is, the effects of various parameters such as the sprayed concrete thickness, the geo-mechanical properties of soil, the tunnel depth, and the fault plane dip angle are studied on the displacements of the ground surface and the tunnel structure, and on the plastic strains of the soil mass around tunnel. The results of each case of reverse and normal faulting are independently discussed and then compared with each other. It is obtained that deeper tunnels show greater displacements for both types of faulting.     

Erratum to: Prediction of Surface Flow by Forcing of Climate Forecast System Reanalysis Data

Water Resources Management -     

Preparation of epoxy-based insulator and optimization of its thermal property by Taguchi robust design method in double base propellant grain application

Taguchi method (orthogonal array, OA₉) was used to design an epoxy insulator by evaluating its glass transition temperature (T _g) for using in a double base (DB) propellant grain. In this design method, three epoxy resins based on diglycidylether bisphenol A (DGEBA), three polyamine curing agents and a DGEBA-based reactive diluent agent were used. The curing process of epoxy resins with polyamines was studied by Fourier transform infrared spectroscopy. The results showed that the curing process was completed at room temperature. The effects of four parameters including resin type, curing agent type, curing agent concentration and diluent quantity were investigated to design a resin formulation with a highest T _g after curing. The obtained results were quantitatively evaluated by the analysis of variance (ANOVA). The results of ANOVA showed that the highest T _g of 86.0 ± 9.0 °C was obtained for the optimum formulation of MANA POX-95 as epoxy resin, H-30 as curing agent and 52 phr H-30. The T _g measured by the experiment was 78.0 ± 0.9 °C. In addition, the single lap shear strength (adhesion strength) of the optimized insulator was measured at 13.66 ± 1.02 MPa. Pull-off test performed on the surface of DB propellant resulted a 1.935 ± 0.003 MPa adhesion strength.     

Determination of key sensor locations for non-point pollutant sources management in sewer network

As the importance of watershed management has emerged for water systems, non-point pollutant sources have been blamed as the main problem of water pollution. To control non-point pollutant sources, it is necessary to monitor sewers connected to the watershed and to analyze their effects on the sewer network. As the cost to monitor a sewer network depends on the number of sensors installed, the monitoring stations should be decided with proper guide of the installation location rule. In present paper, a new method to select the proper sensor location is proposed by combining monitoring information with data mining techniques. To estimate the amount of pollutants by wash-off and to find the sensor locations in a sewer network, three scenarios are considered based on rainfall intensity, influent concentrations and flow rate. The optimal locations of the sensor were selected based on the proposed method to facilitate the management of non-point pollutant source in sewer network. The presented approach can be extended to a complex sewer network system to design a minimum number of sensors and optimum locations for the sensors.     

Model-free kinetic analysis of thermal behavior of urea-formaldehyde microcapsules

In this study, experimental and analytical investigations were conducted concerning kinetics of thermal reactions of urea-formaldehyde microcapsules (UFM). Microencapsulated phase change materials were synthesized via in-situ polymerization using UF resin as shell and drying oil as core, and were characterized by scanning electron microscope (SEM), particle size analysis (PSA) and Fourier transform infrared analysis (FTIR). Accordingly, model-free kinetics (MFK) was used to determine the kinetics of the thermal behavior of UFM. Therefore, Thermogravimetry analysis was conducted at different heating rates of 3, 5, 7, and 10 °C/min. The apparent activation energy was obtained by MFK, which led to identify the reaction mechanisms. The results revealed that there are two stages for degradation of the synthesized microcapsules. Addition of the oil core in the UF microcapsules has hindered one stage of the suggested three stages of the pyrolysis process of UF based resins and the two stages were unified as a single extended stage. Additionally, the measured activation energy showed a low value of 20 kJ/mol due to the presence of oil in the UF microcapsules.     

Linear and nonlinear melt rheology and extrudate swell of acrylonitrile‐butadiene‐styrene and organoclay‐filled acrylonitrile‐butadiene‐styrene nanocomposite

Melt viscoelastic behavior and the die swell of Acrylonitrile‐Butadiene‐Styrene (ABS) and ABS/clay nanocomposites varying in organoclay loading were studied. A pronounced low‐frequency nonterminal behavior exhibited in linear viscoelastic experiments along with an apparent yield stress in transient startup flow tests suggested the existence of a network type, because of interconnection of rubber particles in ABS matrix. From the results of linear and nonlinear viscoelastic measurements, it was found that the incorporation of organoclay can lead to the formation of an additional network formed between organoclay tactoids that caused reduced temperature dependency of linear viscoelastic properties of the nanocomposite samples compared with ABS matrix. The swelling behavior of samples was interpreted using the results of stress relaxation experiments after cessation of steady shear flow. The great reduction in the die swell of nanocomposite samples could be explained in terms of great surface area and anisometric nature of organoclay tactoids and/or platelets, which promote energy consumption and less energy to be stored in chains. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Design of chemical composition and optimum working conditions for trivalent black chromium electroplating bath used for solar thermal collectors

Black chromium is one of the selective surfaces which are commonly used in solar thermal systems. The aim of this research was to design an electroplating bath, using chromium trivalent ions instead of its hexavalent ions because of its toxicity, for black chromium coating to produce a good metallurgical and light properties at low cost and reproducibility. The effect of the additives was investigated and a coating with an absorption coefficient of 0.96 was prepared. The bath contained inexpensive constituents such as chromium sulfate, cobalt chloride, sodium fluoride, sodium hypophosphite and sodium dihydrogen phosphate and did not need any pH control. Thermal resistance, corrosion resistance and adhesion of the coatings as well as throwing power of the bath were investigated. The effect of bright Ni as an undercoat before black chromium electroplating was also investigated. SEM and XRD techniques were employed to characterize the surface microstructure and chemical composition. Spectroscopy was also used to measure absorptance of the coatings.     

Synthetic and physical characterization of phase change materials microencapsulated by complex coacervation for thermal energy storage applications

This paper presents a comprehensive study of encapsulated phase change materials (PCMs). In order to investigate some synthesis parameters, microencapsulated paraffin with gelatin/gum Arabic wall system was prepared by the complex coacervation method and the performance of these microcapsules was evaluated by optical microscopy and differential scanning calorimetry. Further investigations were carried out on the impact of physical parameters on the melting time by studying the constrained melting transformation of an encapsulated PCM in a spherical shell subjected to a constant temperature media. Results indicate successful production of PCM microcapsules with high melting enthalpy (116 kJ/kg), and the effects of diameter and thermal conductivity on melting time of PCMs were demonstrated. Copyright © 2014 John Wiley & Sons, Ltd.