Mild steel green inhibition by Ficus carica leaves extract under practical field conditions

Various electrochemical techniques were employed to study the effectiveness of aqueous Ficus carica (Fig. tree) leaves extract as green corrosion inhibitor for mild steel under field conditions containing 3.5% sodium chloride solution saturated with carbon dioxide. Optimum inhibition efficiency of 90% was obtained using 50 mg/L of inhibitor in the temperature range of 25–40 °C. The mode of action of Ficus carica leave extract as revealed by Polarization studies was shown to act as a mixed inhibitor. The adsorption isotherm of the adsorption of Ficus carica leaves extract on the steel surface was found to follow Langmuir adsorption isotherm. In order to assess the individual contribution of the different constituents of the extract theoretically, the adsorption of the four major organic constituents of Ficus carica leave extract on mild steel were modelled using density functional theory and quench molecular dynamic simulations. Among the four major Ficus carica leaves extract constituent investigated, Caffeoylmalic acid was found to make the most contribution to the overall inhibition action of Ficus carica leaves extract.     

AGGREGATION BEHAVIOR OF COBALT(II), NICKEL(II), AND COPPER(II) BIS(2-ETHYLHEXYL) PHOSPHATE COMPLEXES IN n-HEPTANE

ABSTRACT

The solution behavior of divalent transition metal-bis(2-ethylhexyl) phosphate (M(DEHP)₂, M = cobalt, nickel or copper) complexes in n-heptane have been investigated by vapor pressure osmometry, viscometry and dynamic light scattering. Co(DEHP)₂ complexes tend to form large macromolecular species with a mean aggregation number N_agg as large as 225, and the size of the macromolecular species decreases with increasing Co(DEHP)₂ concentration. In contrast, Cu(DEHP)₂ complexes tend to form small macromolecular species N_agg = 4-8 which increase in size with increasing Cu(DEHP)₂ concentration. On the other hand, Ni(DEHP)₂ complexes (and Ni(DEHP)₂-2H₂O complexes when the molar ratio of H₂O     

Radiation Synthesis of Polyampholytic and Reversible pH-Responsive Hydrogel and Its Application as Drug Delivery System

Graft copolymerization of acrylic acid (AA) and acrylamide (AAm) onto chitosan (CS) was carried out using gamma irradiation. Their swelling behavior was investigated. The hydrogels before and after alkaline hydrolysis were confirmed by FTIR spectroscopic studies. The hydrogels show ampholytic and reversible pH-responsiveness characteristics. The swelling variations were explained according to swelling theory based on the hydrogel chemical structure. The ability of the prepared copolymer to be used as gastric antibiotic delivery system was estimated using amoxicillin trihydrate as a model drug. Release of amoxicillin trihydrate from these investigated hydrogels was studied. For non-ionized drugs, such as amoxicilin trihydrate, the electrostatic polymer/ polymer interactions take place between the cationic groups from CS and the anionic ones from PAA resulting in entrapping the drug into the mesh space of the hydrogel. The non-ionized amoxicillin release was controlled by the swelling/eroding ratio.     

Monitoring the coefficient of variation using a variable sample size control chart

This paper proposes an adaptive Shewhart control chart implementing a variable sample size strategy in order to monitor the coefficient of variation. The goals of this paper are as follows: (a) to propose an easy-to-use 3-parameter logarithmic transformation for the coefficient of variation in order to handle the variable sample size aspect; (b) to derive the formulas for computing the average run length, the standard deviation run length, and the average sample size and to evaluate the performance of the proposed chart based on these criteria; (c) to present ready-to-use tables with optimal chart parameters minimizing the out-of-control average run length as well as the out-of-control average sample size; and (d) to compare this chart with the fixed sampling rate, variable sampling interval, and synthetic control charts. An example illustrates the use of the variable sample size control chart on real data gathered from a casting process.     

Group vertical handoff management in heterogeneous networks

Traditional vertical handover schemes postulate that vertical handovers (VHOs) of users come on an individual basis. This enables users to know previously the decision already made by other users, and then the choice will be accordingly made. However, in case of group mobility, almost all VHO decisions of all users, in a given group (e.g., passengers on board a bus or a train equipped with smart phones or laptops), will be made at the same time. This concept is called group vertical handover (GVHO). When all VHO decisions of a large number of users are made at the same time, the system performance may degrade and network congestion may occur. In this paper, we propose two fully decentralized algorithms for network access selection, and that is based on the concept of congestion game to resolve the problem of network congestion in group mobility scenarios. Two learning algorithms, dubbed Sastry Algorithm and Q‐Learning Algorithm, are envisioned. Each one of these algorithms helps mobile users in a group to reach the nash equilibrium in a stochastic environment. The nash equilibrium represents a fair and efficient solution according to which each mobile user is connected to a single network and has no intention to change his decision to improve his throughput. This shall help resolve the problem of network congestion caused by GVHO. Simulation results validate the proposed algorithms and show their efficiency in achieving convergence, even at a slower pace. To achieve fast convergence, we also propose a heuristic method inspired from simulated annealing and incorporated in a hybrid learning algorithm to speed up convergence time and maintain efficient solutions. The simulation results also show the adaptability of our hybrid algorithm with decreasing step size‐simulated annealing (DSS‐SA) for high mobility group scenario. Copyright © 2015 John Wiley & Sons, Ltd.     

Quasi-nonparametric blind inversion of Wiener systems

An efficient procedure for the blind inversion of a nonlinear Wiener system is proposed. We show that the problem can be expressed as a problem of blind source separation in nonlinear mixtures for which a solution has been previously proposed. Based on a quasi-nonparametric relative gradient descent, the proposed algorithm can perform efficiently even in the presence of hard distortions     

Electronic Level Structure and Single Electron Tunneling Effects in CdSe Quantum Rods

Optical spectroscopy and scanning tunneling microscopy are used to study the size and shape dependence of the electronic states in CdSe quantum rods. Samples having average rod dimensions ranging from 10 to 60 nm in length and 3.5 to 7 nm in diameter, with aspect ratios varying between 3 to 12, were investigated. Both size-selective optical spectroscopy and tunneling spectra on single rods show that the level structure depends primarily on the rod diameter and not on length. With increasing diameter, the band gap and the excited state level spacings shift to the red. The level structure is assigned using a multi-band effective-mass model. We shall also discuss the effect of single electron charging on the tunneling spectra, possibly reflecting the quantum rod level degeneracy, and its dependence on the tunneling junction parameters.     

Gold nanoparticles designed for combining dual modality imaging and radiotherapy

The synthesis of gold nanoparticles functionalized by gadolinium chelates constitutes an attractive way for combining imaging and therapy. The presence of gadolinium chelates allows monitoring their biodistribution after intravenous injection in small animals by magnetic resonance imaging (MRI) while the gold core strongly absorbs the X-ray photons. This feature is exploited for X-ray imaging but also for radiotherapy.     

An explicit and fair window adjustment method to enhance TCP efficiency and fairness over multihops Satellite networks

Transmission control protocol (TCP) is the most widely used transport protocol in today's Internet. Despite the fact that several mechanisms have been presented in recent literature to improve TCP, there remain some vexing attributes that impair TCPs performance. This paper addresses the issue of the efficiency and fairness of TCP in multihops satellite constellations. It mainly focuses on the effect of the change in flows count on TCP behavior. In case of a handover occurrence, a TCP sender may be forced to be sharing a new set of satellites with other users resulting in a change of flows count. This paper argues that the TCP rate of each flow should be dynamically adjusted to the available bandwidth when the number of flows that are competing for a single link, changes over time. An explicit and fair scheme is developed. The scheme matches the aggregate window size of all active TCP flows to the network pipe. At the same time, it provides all the active connections with feedbacks proportional to their round-trip time values so that the system converges to optimal efficiency and fairness. Feedbacks are signaled to TCP sources through the receiver's advertised window field in the TCP header of acknowledgments. Senders should accordingly regulate their sending rates. The proposed scheme is referred to as explicit and fair window adjustment (XFWA). Extensive simulation results show that the XFWA scheme substantially improves the system fairness, reduces the number of packet drops, and makes better utilization of the bottleneck link.