Sensitive Determination of 6-Thioguanine Using Caffeic Acid-functionalized Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Electrochemical Sensor

The study demonstrates the potential application of caffeic acid-functionalized magnetite nanoparticles (CA-Fe₃O₄ NPs) as an effective electrode modifying material for the electrochemical oxidation of the 6-thioguanine (6-TG) drug. The functionalized Fe₃O₄ NPs were prepared using simple wet-chemical methodology where the used caffeic acid acted simultaneously as growth controlling and functionalizing agent. The study discusses the influence of an effective functionalization on the signal sensitivity observed for the electro-oxidation of 6-TG over CA-Fe₃O₄ NPs in comparison to a glassy carbon electrode modified with bare and nicotinic acid (NA)-functionalized Fe₃O₄ NPs. The experiment results provided sufficient evidence to support the importance of favorable functionality to achieve higher signal sensitivity for the electro-oxidation of 6-TG. The presence of favorable interactions between the active functional moieties of caffeic acid and 6-TG synergized with the greater surface area of magnetic NPs produces a stable electro-oxidation signal within the working range of 0.01–0.23 μM with sensitive up to 0.001 μM. Additionally, the sensor showed the strong anti-interference potential against the common co-existing drug molecules such as benzoic acid, acetaminophen, epinephrine, norepinephrine, glucose, ascorbic acid and l-cysteine. In addition, the successful quantification of 6-TG from the commercial tablets obtained from local pharmacy further signified the practical capability of the discussed sensor.     

Design of NS3 VLC module and performance analysis of ad hoc network under VLC and Wi‐Fi layers

Visible light communication (VLC) is the branch of optical wireless communications that uses light‐emitting diodes for the dual purpose of illumination and very‐high‐speed data communication. The main motivation behind the current work is finding alternatives to the saturated radio frequency spectrum, radio frequency security issue, and vulnerability to interferences. The current work is aimed at developing a module for the physical layer of a VLC‐based ad hoc network in network simulation 3. The VLC physical layer module is developed by using the optical signal modules available in the network simulator. The work also includes modelling of VLC‐based transmitter, wireless optical channel, and the optical receiver. Furthermore, the implementation and evaluation of the VLC‐based physical layer is carried out over a typical ad hoc network under different performance metrics. The designed ad hoc network is also tested under Wi‐Fi module followed by its comparison with corresponding ad hoc network under VLC module. The comparison is based on bit error rate curves, system throughput, and gain in received signal‐to‐noise ratio mainly. Finally, the suitability of different modulation schemes is also investigated in the current work for both Wi‐Fi– and VLC‐based ad hoc networks.     

Investigation of copper plates as anode and TiO2/glycine/ZnFe2O4 stabilized on graphite as cathode for textile dyes degradation from aqueous solution under visible light

Journal of Applied Electrochemistry - This study aimed to degrade the two most commonly used dyes in textile industries, Acid Black 172 and Reactive Blue 19, in pollutant water via...     

Bandwidth‐Efficient Selective Retransmission for MIMO‐OFDM Systems

In this work, we propose an efficient selective retransmission method for multiple‐input and multiple‐output (MIMO) wireless systems under orthogonal frequency‐division multiplexing (OFDM) signaling. A typical received OFDM frame may have some symbols in error, which results in a retransmission of the entire frame. Such a retransmission is often unnecessary, and to avoid this, we propose a method to selectively retransmit symbols that correspond to poor‐quality subcarriers. We use the condition numbers of the subcarrier channel matrices of the MIMO‐OFDM system as a quality measure. The proposed scheme is embedded in the modulation layer and is independent of conventional hybrid automatic repeat request (HARQ) methods. The receiver integrates the original OFDM and the punctured retransmitted OFDM signals for more reliable detection. The targeted retransmission results in fewer negative acknowledgements from conventional HARQ algorithms, which results in increasing bandwidth and power efficiency. We investigate the efficacy of the proposed method for optimal and suboptimal receivers. The simulation results demonstrate the efficacy of the proposed method on throughput for MIMO‐OFDM systems.     

Formation of furan in baby food products: Identification and technical challenges

Furan is generally produced during thermal processing of various foods including baked, fried, and roasted food items such as cereal products, coffee, canned, and jarred prepared foods as well as in baby foods. Furan is a toxic and carcinogenic compound to humans and may be a vital hazard to infants and babies. Furan could be formed in foods through thermal degradation of carbohydrates, dissociation of amino acids, and oxidation of polyunsaturated fatty acids. The detection of furan in food products is difficult due to its high volatility and low molecular weight. Headspace solid-phase microextraction coupled with gas chromatography/mass spectrometer (GC/MS) is generally used for analysis of furan in food samples. The risk assessment of furan can be characterized using margin of exposure approach (MOE). Conventional strategies including cooking in open vessels, reheating of commercially processed foods with stirring, and physical removal using vacuum treatment have remained unsuccessful for the removal of furan due to the complex production mechanisms and possible precursors of furan. The innovative food-processing technologies such as high-pressure processing (HPP), high-pressure thermal sterilization (HPTS), and Ohmic heating have been adapted for the reduction of furan levels in baby foods. But in recent years, only HPP has gained interest due to successful reduction of furan because of its nonthermal mechanism. HPP-treated baby food products are commercially available from different food companies. This review summarizes the mechanism involved in the formation of furan in foods, its toxicity, and identification in infant foods and presents a solution for limiting its formation, occurrence, and retention using novel strategies.     

Nanoscale heat transfer investigation of an array of impinging jet systems with different working fluids under crossflow with and without pin fins

In the current numerical study, the thermal and flow field performance of an array of confined multiple jets with air, water, and water‐Al₂O₃ nanofluid in the maximum crossflow configuration over the target plate with and without pin fins is investigated. The numerical results are validated with the experimental data; it is found that a reasonable prediction related to heat transfer can be made. For this study, steady‐state Reynolds‐averaged Navier‐Stokes simulations with the shear‐stress transport $k‐\omega$ turbulence model in ANSYS Fluent were performed. The simulations are performed with volumetric concentration $?=0.2\%$ to 3% and the jet's Reynolds number Re = 15 000 to 35 000. In all cases, the jet outlet‐to‐target plate distance $Z/D$ is 3. It is found that the increase in values of the volumetric concentration of nanoparticles results in a decrease of the Nusselt number and an increase of the convective heat transfer coefficient. This is because there is an increase in thermal conductivity of the working fluid with the increase in the volumetric concentration of nanoparticles for the same Reynolds number. About 81.5% and 89.1% enhancement in the average heat transfer flux values is observed for flat and pin fin‐roughened target plates, respectively, for $?=3\%$.     

EWMA Dispersion Control Charts for Normal and Non‐normal Processes

Process monitoring through control charts is a quite popular practice in statistical process control. This study is planned for monitoring the process dispersion parameter using exponentially weighted moving average (EWMA) control chart scheme. Most of the EWMA dispersion charts that have been proposed are based on the assumption that the parent distribution of the quality characteristic is normal, which is not always the case. In this study, we develop new EWMA charts based on a wide range of dispersion estimates for processes following normal and non‐normal parent distributions. The performance of all the charts is evaluated and compared using run length characteristics (such as the average run length). Extra quadratic loss, relative average run length, and performance comparison index measures are also used to examine the overall effectiveness of the EWMA dispersion charts.Copyright © 2014 John Wiley & Sons, Ltd.     

Electrochemical Properties of Si‐Ge Heterostructures as an Anode Material for Lithium Ion Batteries

Si‐Ge composites have recently been explored as an anode material for lithium‐ion batteries due to their stable cycle performance and excellent rate capability. Although previous reports show the benefits of Si‐Ge composites on electrochemical performance, the specific mechanism and structural effects have been overlooked. Here, the structural effect of Si‐Ge heterogeneous nanostructures on both mechanics and kinetics is systematically studied through theoretical analysis and detailed experimental results. Si‐Ge and Ge‐Si core–shell nanowires are employed for this study. The Si‐Ge core–shell nanowires show a much improved electrochemical performance, especially cycle performance and rate capability, when compared to those of the Ge‐Si core–shell nanowires electrode. On the basis of the detailed experimental results and associated theoretical analysis, its is demonstrated that the strain distribution and Li diffusivity and/or diffusion path are significantly affected by the Si‐Ge heterostructure, which induce different mechanics and kinetics associated with lithium.     

A Logical Framework for the Representation and Verification of Context-aware Agents

We propose a logical framework for modelling and verifying context-aware multi-agent systems. We extend C T L ^? with belief and communication modalities, and the resulting logic ?? _OCRS allows us to describe a set of rule-based reasoning agents with bound on time, memory and communication. The set of rules which are used to model a desired systems is derived from OWL 2 RL ontologies. We provide an axiomatization of the logic and prove it is sound and complete. We show how Maude rewriting system can be used to encode and verify interesting properties of ?? _OCRS models using existing model checking techniques.     

Effect of Accelerated Laboratory Aging on Selected Electrical Properties of Medium-voltage Heat Shrink Cable Joints

Cross linked polyethylene (XLPE) cables are being used extensively in high-voltage power transmission and distribution networks around the world. However, such joints suffer high failure rates in extreme weather conditions. To investigate this issue, selected properties of 15-kV heat shrinkable XLPE cable joints produced by four manufacturers that are widely being used by electric power utilities in Saudi Arabia were evaluated before and after accelerated multi-factor aging. Aging stresses included high voltage, temperature cycling, and periodic applications of switching impulses while keeping joints in air as well as in water. Partial discharge characteristics, dissipation factor at 60 and 0.01 Hz, and breakdown voltages were measured for un-aged and aged joint samples. The results show that partial discharge characteristics supplemented with a 0.01-Hz dissipation factor provide useful diagnostic information about the condition of such joints. Moreover, these properties also provide useful information about the comparative performance of joints produced by different manufacturers.