Synthesis of nano‐niosomal deferoxamine and evaluation of its functional characteristics to apply as an iron‐chelating agent

Deferoxamine has been widely used as an iron‐chelating agent in patients with primary or secondary iron overload deficiency. Deferoxamine is typically administered subcutaneously, intramuscularly, or intravenously by the constant infusion of the drug over 8–12 h. This process is lengthy and uncomfortable for the patients. A nano‐niosomal form of deferoxamine was prepared using the reverse phase evaporation method and evaluated on the basis of morphology, drug release, cytotoxicity, and iron‐chelating efficacy to compare with free drug formulation. The unique structure of niosome enables sustained release of the drug over extended periods. The average particle size was 136 nm and the entrapment efficiency was about 96 %. The biocompatibility of the drug‐loaded nanoparticles showed that the encapsulation of the drug in nano‐niosomes reduces the toxicity of the drug significantly. Our results indicate that the iron‐chelating ability of the entrapped deferoxamine in hepatocytes is higher than the free drug. The nano‐niosomal drug form showed more efficacies versus the free one and it could be a promising clinical intravenous system for delivery of iron‐chelating drugs such as deferoxamine.     

Synthesis of ZnS–Mn nano-luminescent pigment for ink applications

In the present study, ZnS–Mn nano-luminescent pigments were synthesized, using co-precipitation method. Polyvinylpyrrolidine (PVP) surface modifier and Mn dopant concentrations were considered as affecting parameters. The luminescent ink was loaded with two different concentrations of pigments. The obtained ink was silk-screened on different types of fabrics mainly treated cotton, cotton and nylon. Structure, microstructure, luminescent properties of nano-pigments, inks and fabrics and also rheological properties of the inks were investigated. The results showed that the ceramic ink prepared with nano-luminescent pigment had high photoluminescence (PL) intensity. Moreover, the optimum concentrations of Mn and PVP for obtaining maximum PL intensity were found as 2 and 5 wt%, respectively. SEM images of fabrics indicated that nanoparticles were loaded, nonuniformly, on the fibers. The treated linen and nylon fabrics showed maximum and minimum PL intensity, respectively, due to ink penetration depth in the fabrics. Furthermore, washing fastness estimated for all fabrics was in the proper range.     

Day-ahead Resource Scheduling in Distribution Networks with Presence of Electric Vehicles and Distributed Generation Units

Abstract

In this paper a new framework for scheduling of available resources in the distribution networks is developed. In this respect attempts are focused on interactions between charging/discharging profiles of electric vehicles (EVs) and output power of distributed generation units. To reach this goal, the proposed framework is designed as a two-stage optimization procedure. In the first stage, the charging/discharging schedules of EVs are extracted running a linear programing optimization problem taking into account the EV users' constraints and requirements. The usage profiles of the DG units, strategy of buying electricity from the market and also the final charging/discharging patterns of the EVs are set running the second stage of this scheduling framework. The attained mixed-integer non-linear programing optimization problem is linearized and a procedure is organized to check the technical aspect of network. The results show that the proposed energy resource scheduling method satisfies financial and technical goals of network.     

Switched nonlinear singular systems with time‐delay: Stability analysis

This paper presents an approach to the stability analysis of a class of nonlinear interconnected continuous‐time singular systems with arbitrary switching signals. This class of interconnected subsystems consists of unknown but bounded state delay and nonlinear terms, and each subsystem can be globally stable, unstable, or locally stable. By constructing a new Lyapunov‐like Krasovskii functional, sufficient conditions are derived and formulated to check the asymptotic (exponential) stability of such systems with arbitrary switching signals. Then, some new general criteria for asymptotic (exponential) stability with average dwell‐time switching signals are also established. The theoretical developments are demonstrated by two numerical simulations. Copyright © 2014 John Wiley & Sons, Ltd.     

Stability analysis of hybrid switched nonlinear singular time-delay systems with stable and unstable subsystems

The issue of exponential stability of a class of continuous-time switched nonlinear singular systems consisting of a family of stable and unstable subsystems with time-varying delay is considered in this paper. Based on the free-weighting matrix approach, the average dwell-time approach and by constructing a Lyapunov-like Krasovskii functional, delay-dependent sufficient conditions are derived and formulated to check the exponential stability of such systems in terms of linear matrix inequalities (LMIs). By checking the corresponding LMI conditions, the average dwell-time and switching signal conditions are obtained. This paper also highlights the relationship between the average dwell-time of the switched nonlinear singular time-delay system, its stability and the exponential convergence rate of differential and algebraic states. A numerical example shows the effectiveness of the proposed method.     

Synthesis of carbon nanotube-cadmium selenide luminescent nanocomposites using electrophoretic deposition technique

In this research, nanocomposites containing carbon nanotube (CNT)-cadmium selenide (CdSe) quantum dots (QDs) were synthesized and deposited using electrophoretic deposition technique for optical sensors and displays. The composite was first synthesized using silane grafted cadmium selenide and different concentrations of carbon nanotubes, and then deposited on the aluminum electrodes via electrophoresis method. Fourier transformation infrared confirmed the formation of CNT–CdSe nanocomposites. Microstructural investigations using scanning and transmission electron microscopy also showed the presence of the QDs on the surface of carbon nanotubes (CNTs), enhancing their surface roughness. Increasing the applied voltage from 120 to 240 V resulted in the variation of deposition yield in the range of 0.0005–0.0035 g.cm^?2. The deposition yield was first increased and then decreased in all the samples. Photoluminescence studies revealed that the deposited composite has a distinct emission peak in the range of 485–495 nm (green region) under 360 nm illumination depending on the concentration of CNTs. It can be concluded that the deposited composite may be used in field emission displays due to its high efficiency emission in the presence of CNTs.     

Application of oak powder/Fe3O4 magnetic composite in toxic metals removal from aqueous solutions

In this study, the capability of a magnetic composite of oak powder/Fe₃O₄ (OP/Fe₃O₄) for the adsorption of lead, cobalt, and nickel ions from aqueous solutions was examined. Characteristics and structure of oak powder (OP) and OP/Fe₃O₄ magnetic composite were explored by FTIR, SEM, TGA-DTG, VSM, and XRD analysis. The XRD results showed that OP/Fe₃O₄ magnetic composite and OP were in crystalline form. Kinetic behavior of adsorption process was studied using pseudo-first-order, pseudo-second-order, and Elovich models. Results indicated that the pseudo-second-order model (R²?>?0.999) can better describe the kinetic behavior of the metal adsorption process. Equilibrium behavior of the adsorption process was also tested using Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Scatchard isotherm models. The results revealed that the adsorption equilibrium data for three metals match with the Freundlich isotherm model (R²?>?0.99). This indicates the effectiveness of heterogeneous surfaces in comparison with homogeneous ones in the adsorption process of metal ions. Moreover, the results showed that the adsorption process of metal ions with the OP/Fe₃O₄ magnetic composite is physical. Finally, negative values of enthalpy and entropy indicated that the process of the metal ion adsorption is spontaneous and exothermic.     

When will fossil fuel reserves be diminished?

Crude oil, coal and gas are the main resources for world energy supply. The size of fossil fuel reserves and the dilemma that “when non-renewable energy will be diminished” is a fundamental and doubtful question that needs to be answered. This paper presents a new formula for calculating when fossil fuel reserves are likely to be depleted and develops an econometrics model to demonstrate the relationship between fossil fuel reserves and some main variables. The new formula is modified from the Klass model and thus assumes a continuous compound rate and computes fossil fuel reserve depletion times for oil, coal and gas of approximately 35, 107 and 37 years, respectively. This means that coal reserves are available up to 2112, and will be the only fossil fuel remaining after 2042. In the Econometrics model, the main exogenous variables affecting oil, coal and gas reserve trends are their consumption and respective prices between 1980 and 2006. The models for oil and gas reserves unexpectedly show a positive and significant relationship with consumption, while presenting a negative and significant relationship with price. The econometrics model for coal reserves, however, expectedly illustrates a negative and significant relationship with consumption and a positive and significant relationship with price. Consequently, huge reserves of coal and low-level coal prices in comparison to oil and gas make coal one of the main energy substitutions for oil and gas in the future, under the assumption of coal as a clean energy source.     

Lamivudine‐conjugated and efavirenz‐loaded G2 dendrimers: Novel anti‐retroviral nano drug delivery systems

Infection with human immunodeficiency virus (HIV)‐1 causes immunological disorders and death worldwide which needs to be further assisted by novel anti‐retroviral drug delivery systems. Consequently, finding newer anti‐retroviral pharmaceuticals by using biocompatible, biodegradable nanomaterials comprising a nanoparticle as core and a therapeutic agent is of high global interest. In this experiment, a second generation of a negatively charged nano‐biopolymer linear globular G2 dendrimer was carefully conjugated and loaded with well‐known anti‐HIV drugs lamivudine and efavirenz, respectively. They were characterised by a variety of analytical methods such as Zetasizer, Fourier‐transform infrared spectroscopy, elemental analysis and liquid chromatography‐mass spectroscopy. Additionally, conjugated lamivudine and loaded efazirenz with globular PEGylated G2 dendrimer were tested on an HEK293 T cell infected by single‐cycle replicable HIV‐1 virion and evaluated using XTT test and HIV‐1 P24 protein load. The results showed that lamivudine‐conjugated G2 significantly decreased retroviral activity without any cell toxicity. This effect was more or less observed by efavirenz‐loaded G2. These nano‐constructs are strongly suggested for further in vivo anti‐HIV assays.     

Effect of microstructural evolution from nano to micron grain size regime towards structural,magnetic, electrical and microwave properties of gadolinium iron garnet (Gd3Fe5O12)

Journal of Materials Science: Materials in Electronics - The influence of microstructural changes from nano to micron grain size regime towards their structural, magnetic, electrical and microwave...