Development of dispersive liquid-liquid microextraction based on deep eutectic solvent using as complexing agent and extraction solvent: application for extraction of heavy metals

ABSTRACT

A green and efficient dispersive liquid-liquid microextraction method based on a new deep eutectic solvent has been developed for the preconcentration and extraction of cobalt and nickel ions. The deep eutectic solvent is formed by mixing choline chloride (hydrogen bond acceptor) and 4-aminophenol (hydrogen bond donor). Then, it is used as a chelating agent as well as extraction solvent. Under the optimum experimental conditions, the linear ranges for Ni(II) and Co(II) were 0.80–50 and 0.50–50 µgL^?1, respectively, by flame atomic absorption spectrometry. The obtained detection limits were 0.30 and 0.22 µg L^?1 for Ni(II) and Co(II), respectively.     

Case study on handoff strategies for wireless overlay networks

One of the most challenging topics for next‐generation wireless networks is the process of vertical handoff since many of wireless technologies overlap each other and build a heterogeneous topology. Several parameters, pertaining to user/application requirements and network conditions, such as data rate, service cost, network latency, speed of mobile, and etc. must be considered in the handoff process of heterogeneous networks along with RSSI information. In this paper, adaptive fuzzy logic‐based vertical handoff decision‐making algorithms are presented for wireless overlay networks which consist of GSM/GPRS/Wi-Fi/UMTS/WiMAX technologies. The parameters data rate, monetary cost, speed of mobile and RSSI information are processed as inputs of the proposed fuzzy‐based systems. According to these parameters, an output value, which varies between 1 and 10, is produced. This output value is utilized to determine whether a handoff process is necessary or not and to select the best candidate access point in the vicinity. The results show that, compared to the traditional RSSI‐based algorithm significantly enhanced outcomes can be achieved for both user and network as a consequence of the proposed fuzzy‐based handoff systems. The simulation results are also compared with those of classical MADM (Multiple Attribute Decision Making) method, i.e. SAW (Simple Additive Weighting). According to the results obtained, the proposed vertical handoff decision algorithms are able to determine whether a handoff is necessary or not, properly, and select the best candidate access network considering the aforementioned parameters. Moreover, fuzzy‐based algorithm noticeably reduces the number of handoffs compared to SAW‐based algorithm.     

Neuro-fuzzy control strategy for an offshore steel jacket platform subjected to wave-induced forces using magnetorheological dampers

Magnetorheological (MR) damper is a prominent semi-active control device to vibrate mitigation of structures. Due to the inherent non-linear nature of MR damper, an intelligent non-linear neuro-fuzzy control strategy is designed to control wave-induced vibration of an offshore steel jacket platform equipped with MR dampers. In the proposed control system, a dynamic-feedback neural network is adapted to model non-linear dynamic system, and the fuzzy logic controller is used to determine the control forces of MR dampers. By use of two feedforward neural networks required voltages and actual MR damper forces are obtained, in which the first neural network and the second one acts as the inverse dynamics model, and the forward dynamics model of the MR dampers, respectively. The most important characteristic of the proposed intelligent control strategy is its inherent robustness and its ability to handle the non-linear behavior of the system. Besides, no mathematical model needed to calculate forces produced by MR dampers. According to linearized Morison equation, wave-induced forces are determined. The performance of the proposed neuro-fuzzy control system is compared with that of a traditional semi-active control strategy, i.e., clipped optimal control system with LQG-target controller, through computer simulations, while the uncontrolled system response is used as the baseline. It is demonstrated that the design of proposed control system framework is more effective than that of the clipped optimal control scheme with LQG-target controller to reduce the vibration of offshore structure. Furthermore, the control strategy is very important for semi-active control.     

Photovoltaic textile structure using polyaniline/carbon nanotube composite materials

In this paper, an investigation of flexible electrodes for photovoltaic textile structures utilizing polymer‐based organic materials is presented. The composite structure consisting of a blend of water dispersible carbon nanotube:polyaniline (CNT:PANI) components with poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was applied to be used as the hole collecting electrode in photovoltaic textile applications. Both photovoltaic textiles and conventional solar cells were fabricated by using a blend of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT):(6,6)‐phenyl C61‐butyric acid methyl ester (PCBM). All devices were characterized by measuring current versus voltage characteristics under AM 1.5 conditions. The nanoscale morphology of the photovoltaic structures was investigated using scanning electron microscopy and atomic force microscopy.     

Geometrical model to calculate the consumption of sewing thread for 504 over-edge stitch

Sewing thread is one of the most important components of a sewn product that contributes significantly in the useful life of a product. Stitch class 504 is the one which is used in all types of sewn products. Its thread consumption is higher than class 300 and class 400. A mathematical model to predict the sewing thread consumption of stitch class 504 has been proposed in this paper. The model is based on the geometry of the stitch. The proposed model takes into account material thickness and stitch density. The model was validated by using 24 samples (with different material thickness and stitch densities). The accuracy of the model was found to be 99%. Sensitivity analysis revealed that stitch density has 62% effect and material thickness has 38% effect on thread consumption. The proposed model can predict the thread consumption accurately; therefore, it can be used for better estimation of required thread and encourage its better utilization in sewn product industry.     

Evaluation of acupuncture and occlusal splint therapy in the treatment of temporomandibular joint disorders

One hundred patients showed signs and symptoms of temporomandibular joint disorder, were participated in a one year follow up study. The patients were randomly divided into four groups: Acuhealth treatment (group A), occlusal splint therapy (group B), Acuhealth and occlusal splint therapy (group C), and control (group D). Each group comprised 25 patients. The patients were examined before and 3, 6, and 12 months after treatment. At the three month evaluation, the patients who were not satisfied with the treatment outcome were offered additional treatment. The result showed that 87% of the patients treated by Acuhealth unit, 77.3% of the patients treated with occlusal splint therapy, and 91.3% of the patients received Acuhealth and occlusal splint therapy were improved subjectively and clinically after 3 months follow-up. The patients who responded well to treatment initially also responded well in the long run. The study showed that the Acuhealth unit proved to be an ideal early therapy for TMD, and complemented later with occlusal splint.     

MC-CDMA with exponential power profile in Nakagami fading channel

A refined study of multi-carrier code division multiple access transmission over a Nakagami fading channel is proposed. The channel power is modeled with an exponential power profile rather than the uniform profile prevalent in other papers. An expression for the bit error rate (BER) is then derived. Numerical results show that MC-CDMA performances depend on the power dispersion of interferers around the desired user power.