Ion chromatographic determination of perchlorate in foods consumed in Hatay region

Recently, the exposure to perchlorate was emphasised as an important risk factor for human and especially newborn health. A number of studies were focused on this matter. In this study, samples of soil, vegetable (cabbage, spinach, lettuce, carrot, tomato, red cabbage), fruit (orange, mandarin, lemon, grapefruit), water, milk and fish were taken from 8 different regions of Hatay (Samanda?, K?r?khan, Reyhanl?, Amik Plain, Dörtyol, Yaylada??, Alt?nözü, Erzin). An ion chromatography system (Shimadzu C196-E039A model) was used to determine the concentrations of perchlorate in the samples. 2.5 mM Phthalic acid and 2.4 mM tris (hydroxymethyl)aminomethane solutions (pH = 4) were used as the mobile phase. A flow rate of 1.5 ml min⁻¹ and oven temperature of 40 °C were used during the analysis. The foods had perchlorate concentrations in the range of 0.236–1.218 μg kg⁻¹. The perchlorate concentration varied from 0.30 ± 0.01 to 0.94 ± 0.02 μg l⁻¹ in milk samples. Perchlorate concentrations were determined to be lower in the drinking waters (0.44 ± 0.03 μg l⁻¹) compared to irrigation waters (0.59 ± 0.03 μg l⁻¹). Perchlorate concentrations of the fish samples were ranged from 0.38 ± 0.01 to 0.61 ± 0.01 μg kg⁻¹.     

Nonlinear static response of laminated composite plates by discrete singular convolution method

In this paper, large deflection analysis of laminated composite plates is analysed. Nonlinear governing equation for bending based on first-order shear deformation theory (FSDT) in the von Karman sense is presented. These equations have been solved by the method of discrete singular convolution (DSC). Regularized Shannon’s delta (RSD) kernel and Lagrange delta sequence (LDS) kernel are selected as singular convolution to illustrate the present algorithm. The effects of plate aspect ratio, fiber orientation, boundary conditions, thickness-to-side ratio, and applied load on the nonlinear static response of the laminated plate are investigated.     

Effect of cation contamination and hydrated pressure loading on the mechanical properties of proton exchange membranes

Perfluorosulfonic acid (PFSA) polymer membranes are widely used as electrolyte thin films to transport protons in proton exchange membrane (PEM) fuel cells. The mechanical degradation of the membrane represents a common failure mode that limits the operational life of the fuel cells. In the present work, effect of contamination related to cation exchange on the mechanical reliability of PEMs was investigated. We applied the bulge test technique to assess the mechanical properties of Nafion^® PFSA membranes simulating pressure loading on hydrated PEMs in fuel cells. The corresponding elastic moduli of Nafion^® before and after cation exchange were analyzed and compared with the results measured by uniaxial tension experiments at selected humidity conditions, showing increasing stiffness with the increase of cation radius. We also used the out-of-plane tearing test method to characterize the fracture behaviors of PEMs. The effects of cation exchange and water absorption on mechanical and fracture properties of PEMs at different temperatures are discussed in terms of cation and water interactions with the molecular structure of PFSA polymers.     

3D Path Planning for Multiple UAVs for Maximum Information Collection

This paper addresses the problem of path planning for multiple UAVs. The paths are planned to maximize collected amount of information from Desired Regions (DR) while avoiding Forbidden Regions (FR) violation and reaching the destination. The approach extends prior study for multiple UAVs by considering 3D environment constraints. The path planning problem is studied as an optimization problem. The problem has been solved by a Genetic Algorithm (GA) with the proposal of novel evolutionary operators. The initial populations have been generated from a seed-path for each UAV. The seed-paths have been obtained both by utilizing the Pattern Search method and solving the multiple-Traveling Salesman Problem (mTSP). Utilizing the mTSP solves both the visiting sequences of DRs and the assignment problem of “which DR should be visited by which UAV”. It should be emphasized that all of the paths in population in any generation of the GA have been constructed using the dynamical mathematical model of an UAV equipped with the autopilot and guidance algorithms. Simulations are realized in the MATLAB/Simulink environment. The path planning algorithm has been tested with different scenarios, and the results are presented in Section 6. Although there are previous studies in this field, this paper focuses on maximizing the collected information instead of minimizing the total mission time. Even though, a direct comparison of our results with those in the literature is not possible, it has been observed that the proposed methodology generates satisfactory and intuitively expected solutions.     

Preparation and properties of flame retardant poly(urethane‐imide)s containing phosphine oxide moiety

The preparation of new poly(urethane‐imide)s (PUIs) having acceptable thermal stability and higher flame resistance was aimed. Two new aromatic diisocyanate‐containing methyldiphenylphosphine oxide and triphenylphosphine oxide moieties were synthesized via Curtius rearrangement in situ and polymerized by various prepared diols. Four aliphatic hydroxy terminated aromatic based diols were synthesized by the reaction between ethylene carbonate and various diphenolic substances. Chemical structures of monomers and polymers were characterized by FTIR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy. Thermal stabilities and decomposition behaviors of the PUIs were tested by DSC and TGA. Thermal measurements indicate that the polymers have high thermal stability and produce high char. Polymers exhibit quite high fire resistance, evaluated by fire test UL‐94. The films of the polymers were prepared by casting the solution. Inherent viscosities, solubilities, and water absorbtion behaviors of the polymers were reported in. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of ingredients on thermal and mechanical properties of acrylic bone cements

There is a very delicate relation between the amounts of all the ingredients present in the cement composition and the properties of the product. In this study, homogeneous poly(methyl methacrylate) (PMMA) microspheres were prepared by suspension polymerization technique, and used in cement formulations. Various acrylic cements with different compositions were prepared by using PMMA microspheres, methyl methacrylate (MMA) monomer, radiopaque agent of barium sulfate (BaSO₄), inorganic particles of hydroxyapatite (HA), initiator and chain stopping agent of 1‐dodecyl mercaptan (DDM). The effects of these additives on mechanical and thermal properties of the resultant cements were examined. Addition of 8% HA relative to the solid parts caused an increase in both tensile and compressive strengths from 20.40 to 25.20 MPa, and from 84.04 to 89.57 MPa, respectively, while curing temperature was decreased about 3 degrees. Chain stopping agent of DDM caused a sharp decrease about 30 degrees in the curing temperature. Radiopaque agent of barium sulfate caused inverse effect on mechanical and thermal properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Classical enterotoxigenic characteristics of Staphylococcus aureus strains isolated from bovine subclinical mastitis in Van, Turkey

The aim of the present study was to investigate classical enterotoxigenic properties of Staphylococcus aureus strains isolated from cows with subclinical mastitis. For this purpose, 480 milk samples from cows with subclinical mastitis raised in different villages neighbouring Van city Center were collected. A total of 106 S. aureus strains were isolated. Twenty seven isolates (25.5%) were found to be enterotoxigenic by reverse passive latex agglutination (RPLA). Of these, 25 (23.6%) were positive for staphylococcal enterotoxin A (SEA), 2 (1.9%) for SEB. None of the isolates was positive for SEC or SED. This study showed that most S. aureus strains isolated from bovine subclinical mastitis produced SEA compared to other SEs.     

Changes in yield and seed quality traits in rapeseed genotypes by sulphur fertilization

Sulphur is considered more as a soil amendment to remedy alkaline soils rather than a fertilizer in crop production. However, as one of the macronutrients, just as N–P–K, it is able to have a direct and significant effect on yield and quality in some crops. There might be a sound potential of increasing seed yield and quality of rapeseed, the second important oil crop around the world, with the use of sulphur as a fertilizer in cultural practices. Our objective in this study is to determine the effects of sulphur fertilization on seed yield and several seed and oil quality traits in rapeseed. Five rapeseed genotypes were grown for two consecutive growing seasons in Çanakkale, in a RCB design with three replications. The experimental plots were given 0, 100 or 200 kg ha^?1 sulphur along with a fixed amount of 240 kg ha^?1 N. Results indicated that sulphur fertilization had positive effects on seed yield and some of the seed and oil quality components. On the other hand, excessive sulphur fertilization, or naturally occurring high levels in the soil, may have adverse effects in elevating some undesired compounds, such as glucosinolates.     

Analysis of the control strategies for fuel saving in the hydrogen fuel cell vehicles

A hydrogen fuel cell vehicle requires fuel cells, batteries, supercapacitors, controllers and smart control units with their control strategies. The controller ensures that a control strategy predicated on the data taken from the traction motor and energy storage systems is created. The smart control unit compares the fuel cell nominal output power with the vehicle power demand, calculates the parameters and continually adjusts the variables. The control strategies that can be developed for these units will enable us to overcome the technological challenges for hydrogen fuel cell vehicles in the near future. This study presents the best hydrogen fuel cell vehicle configurations and control strategies for safe, low cost and high efficiency by comparing control strategies in the literature for fuel economy.