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The formation of a protein nanobiofilm on the surface of degradable biomaterials such as magnesium (Mg) and its alloys influences metal ion release, cell adhesion/spreading, and biocompatibility. During the early stage of human body implantation, competition and interaction between inorganic species and protein molecules result in a complex film containing Mg oxide and a protein layer. This film affects the electrochemical properties of the metal surface, the protein conformational arrangement, and the electronic properties of the protein/Mg oxide interface. In this study, we discuss the impact of various simulated body fluids, including sodium chloride (NaCl), phosphate-buffered saline (PBS), and Hanks' solutions on protein adsorption, electrochemical interactions, and electrical surface potential (ESP) distribution at the adsorbed protein/Mg oxide interface. After 10 min of immersion in NaCl, atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM) showed a higher surface roughness related to enhanced degradation and lower ESP distribution on a Mg-based alloy than those in other solutions. Furthermore, adding bovine serum albumin (BSA) to all solutions caused a decline in the total surface roughness and ESP magnitude on the Mg alloy surface, particularly in the NaCl electrolyte. Using SKPFM surface analysis, we detected a protein nanobiofilm (∼10-20 nm) with an aggregated and/or fibrillary morphology only on the Mg surface exposed in Hanks' and PBS solutions; these surfaces had a lower ESP value than the oxide layer.

The biodegradation rate of Mg alloy medical devices, such as screws and plates for temporary bone fracture fixation or coronary angioplasty stents, is an increasingly important area of study. In vitro models of the corrosion behavior of these devices use revised simulated body fluid (m-SBF) based on a healthy individual’s blood chemistry. Therefore, model outputs have limited application to patients with altered blood plasma glucose or protein concentrations. This work studies the biodegradation behavior of Mg alloy WE43 in m-SBF modified with varying concentrations of glucose and bovine serum albumin (BSA) to (1) mimic a range of disease states and (2) determine the contributions of each biomolecule to corrosion. Measurements include the Mg ion release rate, electrolyte pH, the extent of hydrogen evolution (as a proxy for corrosion rate), surface morphology, and corrosion product composition and effects. BSA (0.1 g l–1) suppresses the rate of hydrogen evolution (about 30%) after 24 h and—to a lesser degree—Mg2+ release in both the presence and absence of glucose. This effect gets more pronounced with time, possibly due to BSA adsorption on the Mg surface. Electrochemical studies confirm that adding glucose (2 g l–1) to the solution containing BSA (0.1 g l–1) caused a decrease in corrosion resistance (by around 40%), and concomitant increase in the hydrogen evolution rate (from 10.32 to 11.04 mg cm–2 d–1) to levels far beyond the tolerance limits of live tissues.

One of the appealing cases of the neuromorphic research area is the implementation of biological neural networks. The current study offers Multiplierless Hodgkin-Huxley Model (MHHM). This modified model may reproduce various spiking behaviors, like the biological HH neurons, with high accuracy. The presented modified model, in comparison to the original HH model, due to its exact similarity to the original model, has more top performances in the case of FPGA saving and more achievable frequency (speed-up). In this approach, the proposed model has a 69 % saving in FPGA resources and also the maximum frequency of 85 MHz that is more than other similar works. In this modification, all spiking behaviors of the original model have been generated with low error calculations. To validate the MHHM neuron, this proposed model has been implemented on digital hardware FPGA. This approach demonstrates that the original HH model and the proposed model have high similarity in terms of higher performance and digital hardware cost reduction.

Abstract A novel polymethyl methacrylate/boehmite nanocomposite with remarkably enhanced adsorption performance of Cu(II) was synthesized from $${\text{Al}}({\text{NO}}_{3} )_{3} \cdot 9{\text{H}}_{2} {\text{O}}$$Al(NO3)3·9H2O using a facile sol–gel method. The effects of boehmite content, contact time and morphology of hybrid (pH of synthesis) as the main parameters on removal efficiency and removal capability of hybrid on copper ions have been explored. Composites contained between 0.7 and 5wt% boehmite content and those with dissimilar morphology prepared with different pH values showed different adsorption behavior. Batch adsorption experiments show that the adsorption performance of the hybrids was enhanced with increased boehmite and contact time. The highest removal efficiency and adsorption capability were achieved when the hybrid was prepared at pH 8 with associated increased catalytic activity. Graphic abstract

In this paper, an ultra-compact size microstrip Wilkinson Power Divider (WPD) has been proposed with nth harmonic suppression. Two symmetrical lowpass filters have been applied to suppress ...

In this paper, a Min-Max switching controller containing multiple state feedback regulators and fuel flow rate saturation is designed for a high bypass two-spool turbofan engine. Due to the switching nature of Min-Max algorithm and the presence of saturation function, stability analysis is an important issue in the process of controller design. Therefore, a methodology is presented to analyze the stability of the closed loop system. For this objective, the Min and Max selectors and the saturation block are replaced by their nonlinear equivalents and the structure of the control system is transformed into the canonical configuration of Lure’s system. Then, the condition for absolute stability is extracted using the Multivariable Circle Criterion. An asymptotic stability proof is achieved for the closed loop system and the performance of the designed multiregulator Min-Max controller in tracking a desired fan speed scenario and limit management is compared with the well-known Min-Max/SMC technique.

In this study, the oxyamino triazine (OAT) is used to produce a new type of epoxy composites by direct mix technique. OAT is one of the common by-product s in the petrochemical industry. A huge amount of OAT is daily produced in the petrochemical processes without especial application. Here, OAT was used as new filler to the epoxy resin, the weight percent of OAT was varied from 0 to 50 and the mechanical properties (e.g. Young's Module, strength, ductility, impact, hardness) of composites has been studied. The morphology of the OAT-epoxy composites is also studied using X-ray diffraction (XRD) and scanning electron microscope (SEM). Thermal behavior of OAT-epoxy composites is also investigated using thermo-gravimetric analysis (TGA) experiments. The results obtained in this study reveal that the OAT powder can be used as an alternative to epoxy fillers like calcium carbonate in composite manufacturing due to the low density and improvement of mechanical properties.

In this study, polyaniline/multiwall carbon nanotube nanocomposite (PANI/MWCNT) was first synthesized, and a simple organic solar cell was then fabricated containing PANI/MWCNT with cauliflower morphology as an active layer. In the next step; the influence of different parameters such as MWCNT content, the cathode buffer layer, the electrolyte and the presence of dye on the efficiency were experimentally investigated. The effect of carbon nanotubes weight percent on efficiency was studied by measuring the band gap using the UV–Vis characterization. In order to detect the chemical bonding between MWCNT and PANI, the Fourier transform-infrared spectroscopy was used. Also in order to investigate morphology, field emission scanning electron microscopy images of the composite were obtained, and conductivity properties were measured using a standard 4-point DC/voltage method at room temperature. The results showed that by increasing the amount of MWCNT in the composite, the band gap decreased and thus the cell efficiency increased. In a multi-layer cell with cauliflower morphology, due to the excellent synergy between the active layer of PANI/MWCNT and the dye cell components, a significant increase in photovoltaic profile was observed in comparison with simple cells with cauliflower morphology.

This study aims to correlate the microstructure and Volta potential distribution of Ti-Cu welded bimetal to its corrosion initiation sites, using AFM-SKPFM, and SEM-EDS. Local melted zones with Ti-Cu intermetallic precipitates in weld interface and in Cu matrix showed different Volta potential values in comparison with those of Ti and Cu regions. SKPFM revealed that Cu region has a higher Volta potential than that of Ti region. AFM and microstructural images after immersion in corrosive media proved the presence of a galvanic cell. Corrosion mainly extends on Cu side due to the increasing growth of Ti passive film.

In this study, a combination of scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), atomic force microscopy (AFM), scanning Kelvin probe force microscopy (SKPFM), and density functional theory is applied to investigate the evolution of Volta potential and electronic properties of TiO2/Cu2O coupled oxides in presence of chloride-containing corrosive solution. Volta potential and the band gap of Cu2O are increased in presence of chloride ion due to paratacamite (Cu2(OH)3Cl) formation whereas the opposite is seen for TiO2 due to the formation of H4TiO4. The results shows a good correlation between the measured Volta potential difference and the observed corrosion behavior.

A novel compact microstrip lowpass filter is presented in this paper. The structure uses stepped impedance and radial patches and it has the − 3 dB cut-off frequency at 4.39 GHz. The proposed lowpass filter has a wide rejection band from 6 to 30 GHz with rejection level more than − 20 dB. It has also other advantages such as: low insertion-loss

In this paper, a new power divider (PD) is designed initially; then a new PD has been proposed by replacing the conventional transmission lines with rectangular-shaped and radial-shaped resonators....

The critical pitting temperature (CPT) of selective laser melted (SLM) 316 L stainless steel in 1.0 M NaCl was measured and compared with a commercial wrought alloy. Potentiostatic measurements determined a mean CPT value of 16 ± 0.7 °C, 27.5 ± 0.8 °C and 31 ± 1 °C for the wrought alloy, the SLM alloy normal to the build direction and parallel to the build direction, respectively. The lead-in pencil electrode technique was used to study the pit chemistry of the two alloys and to explain the higher CPT values observed for the SLM alloy. A lower critical current density required for passivation in a simulated pit solution was measured for the SLM alloy. Moreover, the ratio of the critical concentration to saturated concentration of dissolving metal cations was found to be higher for the SLM alloy, which was related to its different salt film properties, possibly as a result of the SLM’s distinct microstructure.

In this paper, a very small microstrip low-pass filter (LPF) has presented for utilization in microwave systems. This device is composed of mirrored stepped impedances with two boxes at each side. A transfer function has been extracted from the relevant LC circuit, which expresses the function of this design. The operating frequency of the LPF is located at 3.5 GHz. The proposed LPF blocks a wide rejection with a rejection level of −20 dB or stronger. The return loss of 33 dB is another competence of the LPF. The overall size of the fabricated prototype is 9.5 mm × 5.8 mm (56 mm2). These dimensions maybe give the most compact lowpass filter operating in such frequency among the published work until now. The measurement results mimic the simulations.

The corrosion, passive layer characteristics, and surface morphology of Ti-45Nb in fluoride-containing H2SO4 solutions are evaluated through electrochemical measurements and surface profilometry. Ti-45Nb spontaneously passivated in solutions with 0 and 0.0025 M F−, contrasting with the active-passive behaviour observed at 0.025 and 0.05 M F−. The corrosion resistance of Ti-45Nb decreases with increasing fluoride concentration: the passive current density in 0.05 M F− is 207 μA/cm2, which is eight times greater than the value obtained in 0 M F− (26 μA/cm2).

Conductive adhesives based on Epoxy/Polyaniline/MWCNT (EPM) system doped with Paratoluensulfonic acid (p-TSA) have been successfully synthesis via different methods and characterized. The composites were prepared by in situ synthesis of aniline/MWCNTs within epoxy matrix and direct physical mixing. X-ray diffraction (XRD) spectrum established the existence of MWCNT in the structure and showed that the morphology of samples was amorphous. FT-IR results confirmed that the composites were successfully synthesis and there is strong coupling between the PANi and MWCNT. The microstructure of the conductive adhesives was considered by field emission scanning electron microscopy. The in situ technique contributes for the development of a conducting path with lower amount of PANi/p-TSA. Electrical properties as a function of PANi and MWCNTs contents have also indicated a great interaction between polyaniline, MWCNT and epoxy matrix by in situ polymerization procedure.

The synergestic role of boric acid, as a crystal modifier, and screw dislocation step defects on the crystal growth and formation mechanism of nickel micro-nanocones during electrocrystallization is explained using density functional theory (DFT) and Monte Carlo (MC) calculations. Earlier atomic force microscopy (AFM) studies provided direct evidences on the effect of boric acid on morphology distribution of nickel micro-nanocones and confirmed the presence of terraces and steps due to the spiral growth of screw dislocation. In the presence of boric acid, the formation of nickel-borate complex leads to a decrease in the system’s supersaturation and in turn provides an appropriate condition for screw dislocation driven-growth. DFT and MC simulations reveal that the nickel-borate complex primarily adsorb in the step edges with the lowest adsorption energy barrier, after which the crystal growth is inhibited on these edges resulting in the formation of nanocone structures.

In this paper, a backstepping sliding mode controller is developed for tracking control of spacecraft formation flying on elliptical orbits. The controller is designed in accordance with the nonlinear model of relative motion, and combines the advantages of backstepping and sliding mode control techniques. After applying the backstepping method to incorporate the tracking errors and Lyapunov functions, a sliding mode controller is developed to guarantee the Lyapunov stability, handling all nonlinearities, robustness against uncertainties and tracking the desired trajectory. It is supposed that the leader and follower spacecraft are in a low Earth orbit while J2 perturbation and atmospheric drag are considered as external disturbances. The performance of the proposed controller in tracking the desired formation is compared to a sliding mode controller. Simulation results confirm the effectiveness of the proposed controller.

In the present study, a simple, rapid, sensitive, and environmentally friendly method was proposed for the determination of dobutamine hydrochloride (Dbn.HCl). The method is based on the inhibition of the chemiluminescence (CL) arising from the reaction of luminol and graphene oxide (GO) in a strongly alkaline medium by Dbn.HCl. GO was synthesized and fully characterized by various spectroscopic methods, including TEM and SEM. The mechanisms of the generation and inhibition of CL were also investigated and discussed. The experimental conditions were optimized and under optimum conditions, the method showed a linear response for Dbn.HCl over the concentration range from 3.0 × 10−7 to 5.0 × 10−6 mol L−1. The correlation coefficient (r2) of the calibration line was 0.9972, and the relative standard deviation (RSD) of the method obtained by nine replicate determinations of 2.0 × 10−6 mol L−1 Dbn.HCl was equal to 1.2%. The method was successfully used for the determination of Dbn.HCl in various real samples.

The problem of relative motion control of spacecraft rendezvous process on elliptical orbit is considered in this paper. Due to the presence of nonlinear dynamics and external disturbances, two robust controllers are developed based on sliding mode control theory. The first one is an optimal sliding mode controller; in which optimal control theory is used to reduce the tracking error and fuel cost, and then integral sliding mode control technique is applied to robustify optimal controller. The other controller is a backstepping sliding mode one that is developed based on nonlinear dynamics of spacecraft rendezvous; having applied the backstepping method to synthesis the tracking errors and Lyapunov functions, a sliding mode controller is developed to guarantee the Lyapunov stability, handling of all nonlinearities, robustness against uncertainties as well as tracking the desired position. It is assumed that the chaser and target spacecraft are in a low Earth orbit and subject to the perturbing effects of J2 and atmospheric drag. In addition, two fault tolerant scenarios, i.e. thruster degradation and short thruster failure are also considered to verify the robustness and efficacy of the control approaches. Simulation results confirm the effectiveness of the proposed controllers in reaching to the desired position in case of actuator fault-free and fault tolerant situations.

Polyaniline and polyaniline/multi-walled carbon nanotube (PAni/MWCNT) nanocomposites were synthesized by in-situ chemical oxidative polymerization of aniline. Ammonium peroxydisulphate and p-toluenesulphonic acid were used as an initiator and surfactant dopant, respectively. The molar ratio of monomer unit to initiator and dopant was 1:1:1 and the percentage of MWCNT in PAni varied from 1 to 10 wt%. The structure of the resulting nanocomposite was characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The effects of MWCNT concentration on the electrical properties of the resulting nanocomposites were studied at temperatures between 90 and 300 K. Conductivity increases with the combination of MWCNT in the PAni environment. The strong coupling between the MWCNT and the PAni chains enhances the average localization length and hence conductivity increases for the nanocomposites.

A new approach involving low-temperature system has been developed for the polyaniline/multi-walled carbon nanotubes (PANi/MWCNT) composite in which MWCNT are coated with a layer of PANi in a complete tubular morphology. The MWCNT content varied from 0 to 10 %. The effect of MWCNT content on the thickness of PANi layer was studied. SEM technique was used to investigate the morphology and changes in the dimension of nanotubes. The interaction between PANi and MWCNT considering the nature of chain growth has been explained according to the results of FT-IR analysis. The improvement of thermal stability and crystallinity of the nanocomposites has been evaluated by using TGA and XRD, respectively. The results show the thickness of PANi coating on the surface of MWCNT was depended on the MWCNT content. These nanocomposites have been used for supercapacitor electrodes. The galvanostatic charge–discharge measurements indicated that the PANi/MWCNT composites had greater specific capacitances than pure PANi.

Stability analysis is an essential issue in Min–Max multiregulator control strategy for commercial aircraft engines. In this paper, a Min–Max selector scheme along with a stability analysis method is provided for aeroengine propulsion control. It is assumed that the main regulator is a dynamic compensator and the limit regulators are constant gains. The regulators are determined in such a way that the individual control loops are stable. However, due to the switching nature of Min–Max structure, the stability of single loops does not necessarily ensure the overall system stability. In order to analyze the stability of the presented Min–Maxapproach, the architecture of the control system is transformed into the canonical form of Lure’s system and the condition for absolute stability is specified using Multivariable Circle Criterion. The theoretical results can also be applied to investigate the stability of min-only or max-only schemes. Afterwards, using the provided methodology, the global asymptotic stability is proved for the control system of a high bypass two-spool turbofan engine and the performance of the designed Min–Max controller in tracking a desired fan speed and limit protection in fault-free and fault tolerant situations is compared with the well-known Min–Max/SMC approach.

Aeroengines use a Min-Max selector structure for fuel flow control. This structure should provide desired fan speed command and prevent the engine from violation of physical and operational limits. Recent studies show that there is no guarantee for Min-Max algorithm with linear compensators to protect engine limits during transient state, while limit violation can make dangerous events. In this study, based on a reliable turbofan engine model, a Min-Max selector controller with linear compensators is designed as the traditional controller for gas turbine engines. Then, model predictive control (MPC) technique which can provide optimal control input with regarding input/output constraints is designed as a modern model-based controller. The performance of the Min-Max selector algorithm and model predictive controller are compared in tracking a general fan speed scenario and limit protection. The simulation results show that the MPC method provides faster response and prevent limit violation in compare with Min-Max approach.

A simple and sensitive chemiluminometric method is described for the determination of tetracycline (TC) and oxytetracycline (OTC) in their hydrochloride form on the basis of drastic enhancement of the chemiluminescence (CL) from the luminol/L-cysteine-capped CdTe quantum dots (QDs)/sodium periodate system, caused by the presence of TC and OTC hydrochloride. The method uses pH value at which tetracyclines have proven to be stable. Response surface methodology was exploited for optimizing the experimental conditions. The synthesized QDs were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy, and photoluminescence spectroscopy. A possible mechanism of the CL system was proposed based on the CL spectra and the effect of some specific radical-scavengers on the system. Under the optimum conditions linear dynamic ranges of 5.0×10−8–6.0×10−6 mol L−1 and 5.0×10−8–8.0×10−6 mol L−1 were observed for TC and OTC, respectively with corresponding detection limits of 2.2×10−8 mol L−1 and 3.0×10−8 mol L−1. The precision (RSD%) for five replicate determinations of TC and OTC were respectively no more than 3.4% and 4.0%. The method was satisfactorily applied to the determination of TC.HCl and OTC.HCl in water samples, pharmaceutical formulations, and honey.

A simple and highly sensitive chemiluminescence (CL) method is reported for the determination of naphazoline hydrochloride (NH). It was found that the weak CL from the reaction of luminol and KIO4 in an alkaline medium could be highly amplified by cysteine-capped cadmium telluride quantum dots (QDs) and the enhanced CL was effectively quenched by NH and this finding was utilized as a basis for the determination of NH. The QDs were synthesized in aqueous medium and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis and photoluminescence spectroscopy. A possible mechanism was proposed for the CL system based on radical identification experiments, along with CL spectrum of the system. The experimental parameters were optimized by the reliable response surface methodology (RSM). Under the optimized experimental conditions, the proposed method allowed the determination of NH over the range of 5.0 × 10(-10) -2.0 × 10(-7) mol/L (r(2) = 0.9993, n = 10). The precision (RSD%) of the method, obtained from five replicate determinations of 2.0 and 150 nmol/L NH, was found to be 1.0% and 1.3%, respectively. The method was successfully applied to the determination of NH in pharmaceutical formulations and human urine and serum samples with results corroborated with the aid of those obtained from a standard method.

Scanning electron microscopy (SEM), atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM) were used to examine the role of constituent phases of a NiAl bronze in corrosion initiation in HCl solution. Volta potential revealed anodic character of κ phases with tens of mV higher than copper rich α phase as cathodic matrix. A correlation between SKPFM results and Work function values of constituents was obtained. SEM and AFM images revealed that the iron rich κ phases are the most preferential sites for corrosion initiation.

A lap joint of AA3003 and pure copper was produced by friction stir welding and the induced interfaces were investigated. Interfacial regions were characterized by SEM–EDS, AFM, SKPFM, OM and Vickers micro-hardness. Multimodal Gaussian distribution (for characterization of surface potential patterns) showed the formation of multiple compounds. A quantitative correlation between microstructure constituents and Volta potential distribution was recognized and confirmed by corrosion attacked sites observations. It was observed that the Al-rich regions proximate the dispersed Cu particles and Cu–Al intermetallics were most susceptible to corrosion attack initiation due to a galvanic driving force between these surface constituents.

Valproic acid (VA) is an acidic anticonvulsant and mood stabilizing drug with very weak fluorescence and absorption properties. A simple, inexpensive and sensitive method was established for determination of VA using thiogycolic acid (TGA)-capped CdTe quantum dots (QDs) based on pH-dependent fluorescence of the prepared QDs. The TGA-capped CdTe QDs of various sizes were successfully synthesized in aqueous medium and characterized by fluorescence spectroscopy, UV–vis absorption spectra, infrared spectroscopy and transmission electron microscopy (TEM). Under the optimal conditions, plotting ln( F 0 / F ) versus concentration of VA showed a linear relationship in the range of 0.3–7.5 mg/L with correlation coefficient of 0.998. The limit of detection (LOD) was 0.24 µg mL −1 . The proposed method was successfully applied for determination of VA in commercial tablets, human serum, and urine samples satisfactorily.

The effect of microstructure on corrosion behavior of a solid-state explosion welded Ti-Cu bimetal is investigated by means of alternating current-direct current (AC-DC) electrochemical measurements, optical microscopy, scanning electron microscopy, and scanning Kelvin probe force microscopy (SKPFM). The results indicate that the titanium regions in the welding interface, local melted zone (LMZ), and LMZ-Cu interface are potential sites for initiation of corrosion attacks. SKPFM mapping clearly shows that before exposure of the sample to a 3.5% NaCl corrosive solution and at the beginning of the exposure, the Cu side of the bimetal has a higher Volta potential in comparison to that of the Ti region, and thus acts as a cathode. Electrochemical measurements also confirm that titanium acts as an anode and copper as a cathode, in the first moments of immersion, in accordance with macroscopic observations and SKPFM results. However, by growing a passive layer of titanium oxide and titanium hydroxide on the Ti side after about 1 h exposure to the corrosive medium, the titanium side becomes nobler and the polarity arrangement in the galvanic couple reverses.

An enhanced thiosemicarbazide(TSC)-H 2O2 chemiluminescence (CL) system was established and proposed as a new analytical method for determination of b-lactam antibiotics, ampicillin sodium and amoxicillin at microgram levels. The method is based on the inhibition of CL emission accompanying oxidation of TSC by H 2O2 in alkaline medium. The effect of anionic, cationic, and non-ionic surfactants on the CL emission of the system was studied. Both N-cetyl- N,N,N- trimethylammonium bromide (CTMAB) and Triton X-100, unlike sodium dodecyl sulfate (SDS), reinforced the CL intensity and were efficient to approximately the same level. The effect of the presence of eight non-aqueous solvents on the CL system was also investigated. Upon addition of both of the non-ionic surfactant, Triton X-100, and the non-aqueous solvent, N,N- dimethyl formamide (DMF), the intensity of the CL reaction was increased 100-fold. This method allows the measurement of 25-545 mg amoxicillin, and 35-350 mg ampicillin sodium. The detection limits are 8 mg for amoxicillin and 9 mg for ampicillin sodium. The relative standard deviations of six replicate measurements of 200 mg amoxicillin and 200 mg ampicillin sodium were 1.9 and 2.1%, respectively. The effect of foreign species on the determination of amoxicillin and ampicillin sodium was also examined. The proposed method was successfully applied to the determination of ampicillin sodium and amoxicillin in some pharmaceutical dosage forms. Copyright © 2008 John Wiley & Sons, Ltd.

Silver nanoparticles were synthesized by chem- ical reduction method. The surface of silver nanoparticles (SNPs) was modified using polyvinylpyrrolidone to make them more compatible with pyrrole. Surface-modified SNPs were dispersed in pyrrole and polymerized via in situ oxi- dative polymerization technique. The molar ratio of mono- mer unit to initiator and dopant was 1:1:1 and the weight percent of SNPs in polymer matrix was varied from 1 to 10. The properties of polypyrrole-silver nanocomposites have been characterized using Fourier transform infrared spec- troscopy, X-ray diffraction, scanning electron microscope, transmission electron microscope, thermo-gravimetric ana- lysis and four-probe resistivity meter. All these character- izations indicate that the polypyrrole-silver nanocomposite is successfully synthesized via in situ oxidative polymeri- zation and electrical extent shows suitable conductivity.

Correction for ‘Enhanced luminol–O2 chemiluminescence reaction by CuO nanoparticles as oxidase mimics and its application for determination of ceftazidime’ by Mortaza Iranifam et al., Anal. Methods, 2016, 8, 3816–3823.

A simple and highly sensitive chemiluminescence (CL) method is reported for the determination of naphazoline hydrochloride (NH). It was found that the weak CL from the reaction of luminol and KIO4 in an alkaline medium could be highly amplified by cysteine-capped cadmium telluride quantum dots (QDs) and the enhanced CL was effectively quenched by NH and this finding was utilized as a basis for the determination of NH. The QDs were synthesized in aqueous medium and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis and photoluminescence spectroscopy. A possible mechanism was proposed for the CL system based on radical identification experiments, along with CL spectrum of the system. The experimental parameters were optimized by the reliable response surface methodology (RSM). Under the optimized experimental conditions, the proposed method allowed the determination of NH over the range of 5.0 × 10(-10) -2.0 × 10(-7) mol/L (r(2) = 0.9993, n = 10). The precision (RSD%) of the method, obtained from five replicate determinations of 2.0 and 150 nmol/L NH, was found to be 1.0% and 1.3%, respectively. The method was successfully applied to the determination of NH in pharmaceutical formulations and human urine and serum samples with results corroborated with the aid of those obtained from a standard method.

In this paper, a new approach of sliding mode control is presented for the control of a MEMS optical switch in which electrical, mechanical, and optical models are considered. In this method, fuzzy gain scheduling is employed to fight against uncertainties. By applying fuzzy method, sliding mode gains are tuned according to real-time error which leads to the optimization of the energy consumption and accurate control process. Robustness of the proposed controller is evaluated in the presence of uncertainties created by measurement errors, un-modeled dynamics, parametric errors, and external disturbances. This work improves upon the works previously done in this field of research by reducing the effects of modeling errors and uncertainty limits in calculating control law. Behavior of the control system is also kept robust and precise throughout. Simulation results show that the proposed approach outperforms the conventional sliding mode controller in terms of efficiency and accuracy.

Polypyrrole-multiwall carbon nanotube (PPy-MWCNT) nanocomposites were chemically synthesized via in situ oxidative polymerization of pyrrole. Ammonium peroxydisulfate and p-toluenesulfonic acid were used as an initiator and surfactant dopant, respectively. The molar ratio of monomer unit to initiator and dopant was 1:1:1, and the percentage of MWCNT in PPy varied from 1 to 10 wt.%. PPy-MWCNT nanocomposites were characterized to study chemical structure, morphology, thermal, electrical, and surface properties. To accomplish this, the samples have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, four probe resistivity method, and atomic force microscopy. The results showed that PPy-MWCNT nanocomposites were successfully synthesized via in situ oxidative polymerization method, and also, electrical conductivity of nanocomposites was increased when the content of MWCNT increase.