Alumina coated with oxazolone derivative for extraction of trace amounts of cadmium and copper from water and plant samples

A solid phase extraction procedure is proposed for simultaneous separation and preconcentration trace amounts of Cu(II) and Cd(II) using alumina coated with N'-{4-[4-{1-[4-(dimethylamino)phenyl]methylidene}-5-(4-H)oxazolone]phenyle}acetamide and determination by flame atomic absorption spectrometry. Using 0.1g of the sorbent, the metal ions were sorbed at pH 7 and recovered with 5.0 mL of 0.5 mol L(-1) HNO(3). It was found that extraction can be performed from the sample volumes of 2000 and 800 mL for Cu and Cd, respectively (preconcentration factors of 400 for Cu and 160 for Cd). Obtained sorption capacities for 1g sorbent were 8 mg Cu and 14 mg Cd. The linearity was maintained in the concentration range of 0.1 ng mL(-1) to 7.0 μg mL(-1) for Cu and 0.13 ng mL(-1) to 2.0 μg mL(-1) for Cd in the original solution. Eight replicate determinations of a mixture containing 1.0 μg mL(-1) each of the elements in the final solution gave relative standard deviation ±1.6 and ±1.3% for Cu and Cd, respectively. The detection limit was calculated as 0.06 and 0.05 ng mL(-1) for Cu and Cd, respectively. The proposed method was successfully applied to the determination trace amounts of Cu and Cd in the water and plant samples.     

Early detection of anastomotic leaks after colorectal surgery by measuring endotoxin in the drainage fluid

BACKGROUND/AIMS: Early detection of anastomotic leaks after colorectal anastomosis is essential for adequate intervention to prevent peritonitis. We investigated whether the measurement of endotoxin (LPS) concentrations in the drainage has any value for the early detection of anastomotic leaks. MATERIALS AND METHODS: Twenty two patients with colorectal anastomosis were enrolled in this study, 3 developed clinically established signs of anastomotic leaks and 19 recovered without complications. LPS concentrations in the drainage, the total daily excreted LPS amounts, leukocyte and thrombocyte counts, plasma urea and creatinine, and body temperature were measured for up to 8 days after surgery and tested for their value to detect anastomotic leaks. RESULTS: LPS concentrations in the drainage fluid and daily excreted LPS amounts of patients with anastomotic leaks were significantly higher compared to the group without anastomotic leaks. On the third postoperative day, LPS concentrations ranged from 5270 to 6750 pg/ml in patients with anastomotic leaks and from 1 to 1848 pg/ml in patients without complications. Total daily excreted LPS amounts were 270-675 ng/day in patients with anastomotic leak and 0-92 ng/day in patients without anastomotic leaks. Both LPS-related parameters allowed reliable detection of anastomotic leaks on day 3 after surgery (Student's t-Test, p < 0.0005), while leukocyte and thrombocyte counts, plasma urea and creatinine, and body temperatures of both patient groups were not significantly different at any time (p > 0.05). CONCLUSION: We found that the measurement of LPS concentrations in the drainage and the daily excreted LPS amount could be valuable parameters for the early detection of anastomotic leaks as early as on the third post-operative day.     

Dispersed solar thermal generation employing parabolic dish-electric transport with field modulated generator systems

This paper discusses the application of field modulated generator systems (FMGS) to dispersed solar-thermal-electric generation from a parabolic dish field with electric transport. Each solar generation unit is rated at 15 kWe and the power generated by an array of such units is electrically collected for insertion into an existing utility grid. Such an approach appears to be most suitable when the heat engine rotational speeds are high ( >6000 r/min) and, in particular, if they are operated in the variable speed mode and if utility-grade a.c. is required for direct insertion into the grid without an intermediate electric energy storage and reconversion system. Predictions of overall efficiencies based on conservative efficiency figures for the FMGS are in the range of 25 per cent and should be encouraging to those involved in the development of cost-effective dispersed solar thermal power systems.     

Thermal analysis of air-cooled PEM fuel cells

Air-cooled proton exchange membrane fuel cells (PEMFCs), having combined air cooling and oxidant supply channels, offer significantly reduced bill of materials and system complexity compared to conventional, water-cooled fuel cells. Thermal management of air-cooled fuel cells is however a major challenge. In the present study, a 3D numerical thermal model is presented to analyze the heat transfer and predict the temperature distribution in air-cooled PEMFCs. Conservation equations of mass, momentum, species, and energy are solved in the oxidant channel, while energy equation is solved in the entire domain, including the membrane electrode assembly (MEA) and bipolar plates. The model is validated with experiments and can reasonably predict the maximum temperature and main temperature gradients in the stack. Large temperature variations are found between the cool incoming air flow and the hot bipolar plates and MEA, and in contrast to water-cooled fuel cells, significant temperature gradients are detected in the flow direction. Furthermore, the air velocity and in-plane thermal conductivity of the plate are found to play an important role in the thermal performance of the stack.     

Study of the anticorrosive properties of polypyrrole/polyaniline bilayer via electrochemical techniques

In this work, using electrochemical techniques the authors investigated the protective properties of a polypyrrole/polyaniline bilayer as a conductive polymer. A polypyrrole/polyaniline bilayer was deposited on carbon steel substrate by potentiostatic method. The electric capacitance and resistance of the films were monitored with the immersion time in a corrosive solution to investigate the water permeability of the films. Polypyrrole/polyaniline bilayer has a relatively low permeability and good catalytic behavior in passivation of carbon steel in longer periods. The results show that the bilayer has a better anticorrosive behavior compared to homopolymers (polypyrrole and polyaniline).     

Mechanical behavior modeling of nanocrystalline NiAl compound by a feed-forward back-propagation multi-layer perceptron ANN

In this paper, an artificial neural network (ANN) model has been developed to predict the yield and tensile strengths of hot pressed NiAl intermetallic compound based on the experimental data from Albiter et al. [A. Albiter, M. Salazar, E. Bedolla, R.A.L. Drew, R. Perez, Mater. Sci. Eng. A 347 (2003) 154]. The predicted results, with a correlation relation between 0.9791 and 0.9921, show a very good agreement with the experimental values. Furthermore, the sensitivity analysis was performed to investigate the importance of the effects of chemical composition and temperature on the mechanical behavior of hot pressed NiAl intermetallic compound.     

Study of payment scheduling problem to achieve client–contractor agreement

This paper aims to determine simultaneously the amount, timing, and location of progress payments in projects in order to achieve a set of equitable solutions in the client–contractor negotiation process. The objective function tries to minimize the distance between the final solutions and the best achievable solutions of the client and the contractor. Due to combinatorial nature of the proposed problem, an iterative two-stage search method is proposed. In the first stage, a set of payments is determined to maximize the contractor's net present value (NPV), another set to maximize the client's NPV, and another one to minimize the objective function. In the second stage, activities are rescheduled to improve the solutions by fixing the amount and location of progress payments. A hybrid meta-heuristic algorithm named GASA, along with a simulated annealing (SA) and a genetic algorithm (GA), is introduced for the first stage, while the activities are optimally scheduled in the second stage. It has been shown that SA is better for the contractor’s objective function and GA for the client’s objective function, but GASA is the best in all situations; besides, the proposed method has represented to be an efficient approach to obtain non-dominated solutions in the client–contractor negotiation process.     

Feldspar/titanium dioxide/chitosan as a biophotocatalyst hybrid for the removal of organic dyes from aquatic phases

Feldspar/titanium dioxide/chitosan hybrid, a photoactive biocompatible adsorbent for anionic dyes, was synthesized, characterized, and successfully tested. The adsorbent characterization, pH role, adsorbent dose effect, equilibrium data, kinetic plats, and thermodynamic parameters are reported. The point of zero charge for the hybrid was measured to be 8.3, and the most favorable pH range for the adsorption process was found to be below this pH value. The adsorption equilibrium study demonstrated that the Freundlich model was best fitted to the experimental data. Without UV light exposure, the prepared adsorbent adsorbed 72 mg of Acid Black 1 (AB1)/g of sorbent (86% removal) from a 100‐mL solution with an initial dye concentration of 50 mg/L, whereas UV irradiation resulted in an increase in the elimination of AB1 dye (97% removal). The kinetic data was depicted well by the pseudo‐second‐order model. The thermodynamic parameters indicated that the reaction between the hybrid and the dye was exothermic and also spontaneous at lower temperatures. In the batch desorption process, several aqueous solutions adjusted to different pH values were tested, and the best desorption performance (90% desorption) was achieved at pH 11. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40247.     

Rapid determination of soil unconfined compressive strength using reflectance spectroscopy

Bulletin of Engineering Geology and the Environment - Understanding the physical and especially mechanical properties of forest soils is very important in forest engineering operations including...