Green synthesis of Fe3O4/ZnO magnetic core-shell nanoparticles by Petasites hybridus rhizome water extract and their application for the synthesis of pyran derivatives: Investigation of antioxidant and antimicrobial activity

In this research, Fe₃O₄/ZnO magnetic core-shell nanoparticles (Fe₃O₄/ZnO MCNPs) were synthesized through a green method using Petasites hybridus rhizome water extract as a reducing and stabilizing agent. The morphology and size of the Fe₃O₄/ZnO MCNPs was identified by X-ray diffraction, scanning electron microscopy, and Energy-dispersive X-ray spectroscopy (EDX) analysis. The catalytic activity of the Fe₃O₄/ZnO MCNPs was evaluated in the efficient and green preparation of pyran derivatives in excellent yield using three-component reactions of dimedone, aldehydes, and malononitrile in ethanol at room temperature. The ability of some synthesized compounds to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical was measured and the results proved this observation. Moreover, the antimicrobial activity of some synthesized compounds was proved by employing the disk diffusion test on Gram-positive and Gram-negative bacteria. The results for the disk diffusion test showed that compounds ( 4c, 4d, 4f and 4g ) prevented bacterial growth.     

ZnO/Fe3O4 nanoparticles promoted green synthesis of pyrazolo pyrimidinones: Study of antioxidant activity

The preparation of pyrazolo pyrimidinone derivatives was performed by using five component reactions of phthalaldehyde, cyanomethylamine, electron deficient acetylenic compounds, isocyanate, hydrazine, and catalytic amounts of ZnO/Fe₃O₄-magnetic nanoparticles as a high performance catalyst under ultrasonic conditions at ambient temperature in aquause media at room temperature. It should be mentioned that this catalyst was prepared using Spinacia oleracea water extract. In addition, for investigation of antioxidant ability, radical trapping by DPPH and reducing power of ferric ion experiments was performed. As a result, synthesized compounds show excellent radical trapping by DPPH and good reducing ability of ferric ion. The current procedure has the benefits for instance excellent yield of reaction, green media, and easy separation of product and catalyst.     

A Novel Synthesis and Antioxidant Evaluation of Functionalized [1,3]‐Oxazoles Using Fe3O4‐Magnetic Nanoparticles

In this research, green procedure was employed for biosynthesis of magnetic nanoparticles of iron oxide (Fe₃O₄‐MNPs) by reduction of ferric chloride solution with Orange peel water extract. Also, dihydro‐2H‐cyclopenta[d][1,3]oxazole was generated through multicomponent reaction of 1,3‐oxazole‐2(3H)‐thione, dialkyl acetylenedicarboxylates, α‐haloketones, and Fe₃O₄‐MNPs as catalyst at ambient temperature in good yield. Initially, 1,3‐oxazole‐2(3H)‐thione derivatives as one of the precursors are produced through the reaction of alkyl bromides, isothiocyanate, sodium hydride, and Fe₃O₄‐MNPs as catalyst water at ambient temperature in 83–95% yields. Also, diphenyl‐picrylhydrazine radical trapping and ferric reduction activity potential assays are used for evaluation of antioxidant activity of some synthesized compounds. Among investigated compounds, 4b has good power for radical trapping activity and 4d has good reduction power to butylated hydroxytoluene and 2‐tert‐butylhydroquinone.     

Combination of CoWO4 and Ag3VO4 with Fe3O4/ZnO nanocomposites: Magnetic photocatalysts with enhanced activity through p-n-n heterojunctions under visible light

As novel visible-light-induced photocatalysts, a series of magnetically recyclable Fe₃O₄/ZnO/CoWO₄/Ag₃VO₄ nanocomposites were fabricated through successive combination of Fe₃O₄/ZnO with CoWO₄ and Ag₃VO₄. A facile refluxing-calcination procedure was employed to prepare these nanocomposites and they were characterized by various sophisticated instruments including XRD, EDX, SEM, TEM, UV–vis DRS, FT-IR, PL, as well as VSM and subsequently tested for photocatalytic degradations of three dyes and one colorless pollutants. The Fe₃O₄/ZnO/CoWO₄/Ag₃VO₄ (20%) nanocomposite indicated excellent photodegradation for RhB under visible light, which is 78.4, 4.44, and 3.19 times superior to the Fe₃O₄/ZnO, Fe₃O₄/ZnO/Ag₃VO₄, and Fe₃O₄/ZnO/CoWO₄ samples, respectively. Production of more electron-hole pairs due to presence of two small band gap semiconductors and retardation of the charge carriers from recombination due to formation of p-n-n heterojunctions are the main factors enhancing the photocatalytic performance. Additionally, the nanocomposite was readily recovered from the reaction solution using a magnet and its photocatalytic activity remained reasonable after some repetitive cycles.     

Preparation of New Magnetic Nanocatalysts Based on TiO2 and ZnO and Their Application in Improved Photocatalytic Degradation of Dye Pollutant Under Visible Light

Photocatalytic degradation of methyl orange (MO) as a model of an organic pollution was accomplished with magnetic and porous TiO₂/ZnO/Fe₃O₄/PANI and ZnO/Fe₃O₄/PANI nanocomposites under visible light irradiation. The structures of nanocomposites were characterized by various techniques including UV–Vis absorption spectroscopy, XRD, SEM, EDS, BET and TGA. Optical absorption investigations show two λ_max at 450 and 590 nm for TiO₂/ZnO/Fe₃O₄/PANI nanocomposites respectively possessing optical band gaps about 2.75 and 2.1 eV smaller than that of the neat TiO₂ and ZnO nanoparticles. Due to these optical absorptions, the nanocomposites can be considered promising candidates as visible light photocatalysts to produce more electron‐hole pairs. The degradation of MO, extremely increased using polymeric photocatalysts and decolorization in the presence of visible light achieved up to 90% in less than 20 min in comparison with the neat nanoparticles (about 10%). All these advantages promise a bright future for these composites as useful photocatalysts. The degradation efficiency of MO using stable nanocomposites was still over 70% after ten times reusing. The highest decolorizing efficiencies were achieved with 0.75 g L^?1 of catalyst and 10 mg L^?1 of MO at natural pH under visible light irradiation in less than 20 min.     

Preparation and characterization of novel polyimide/functionalized ZnO bionanocomposite for gas separation and study of their antibacterial activity

In the present investigation novel Polyimide/functionalized ZnO (PI/ZnO) bionanocomposites containing amino acid (Methionine) and benzimidazole pendent groups with different amounts of modified ZnO nanoparticles (ZnO NPs) were successfully prepared through ultrasonic irradiation technique. Due to the high surface energy and tendency for agglomeration, the surface ZnO NPs was modified by a coupling agent as 3- methacryloxypropyl-trimethoxysilane (MPS) to form MPS-ZnO nanoparticles. The ultrasonic irradiation effectively changes the rheology and the glass transition temperature and the crystallinity of the composite polymer. PI/ZnO nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). TEM analysis showed that the modified ZnO nanoparticles were homogeneously dispersed in polymer matrix. The TGA results of PI/ZnO nanocomposites showed that the thermal stability is obviously improved the presence of MPS-ZnO NPs in comparison with the pure PI and that this increase is higher when the NP content increases. The permeabilities of pure H₂, CH₄, O₂, and N₂ gases through prepared membranes were determined at room temperature (25 °C) and 20 bar feed pressure. The membranes having 20% ZnO showed higher values of H₂ permeability, and H₂/CH₄ and H₂/N₂ ideal selectivities (the ratio of pair gas permeabilities) compared with other membranes. The antibacterial activity of bionanocomposite films was tested against gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Further, it was observed that antibacterial activity of the resulting hybrid biofilms showed somewhat higher for gram-positive bacteria compared to gram-negative bacteria.     

Design and synthesis of diethyl(substituted 2-benzylbenzofuran-3-yl)phosphonates as antioxidant and antimicrobial agents

In continuance of our effort to improve novel and potent synthetic approaches for various bioactive phosphorylated heterocycles via C─P bond formation, a series of diethyl substituted(2-benzylbenzofuran-3-yl)phosphonate derivatives ( 4a - j ) was synthesized by one-pot reaction of various diversely substituted salicylaldehydes, phenyl acetylene, and diethyl phosphite using CuO nanoparticles as catalyst in 1:1 ethanol and water under room temperature. The new compounds have been studied for their radical scavenging activity by DPPH, H₂O₂, and NO approaches and antimicrobial activity assay against bacteria and fungi by disk diffusion method.     

Fabrication of Fe3O4@SiO2 nanocomposites to enhance anticorrosion performance of epoxy coatings

SiO₂‐coated Fe₃O₄ (Fe₃O₄@SiO₂) nanocomposites were prepared by sol–gel method, and the anticorrosion performance of composite coatings was discussed. The structure of the Fe₃O₄@SiO₂ nanocomposites was verified through Fourier transform infrared, X‐ray diffraction, and scanning electron microscopy. Composite epoxy coatings with same concentrations of Fe₃O₄ and Fe₃O₄@SiO₂ were measured by scanning electron microscopy contact angle meter. More importantly, the Fe₃O₄@SiO₂ nanocomposites not only obtained a homogeneous dispersion and compatibility in epoxy resin but also exhibited an obvious superiority in enhancing the anticorrosion performance of epoxy coatings. Furthermore, the anticorrosion mechanism of Fe₃O₄@SiO₂/epoxy composite coating was tentatively discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Improving barrier properties of polyethylene/Fe2O3-modified nanographene nanocomposites in a magnetic field

The present work aims at improving the barrier properties of high molecular weight Polyethylene/ graphene nanoplatelets (HMWPE/GnP) nanocomposites by aligning the embedded modified graphene nanoparticles in a magnetic field. Graphene nanoplatelets (GnP) were modified by magnetic Fe₂O₃ to produce Fe₂O₃-modified Graphene, GnP-mFe₂O₃. The magnetic properties of Fe₂O₃ were previously characterized by the vibrating sample magnetometer (VSM) method and resulting GnP-mFe₂O₃ nanoparticles were characterized by Fourier transform infrared (FTIR) analysis. HMWPE/GnP nanocomposites were prepared via melt mixing. The prepared nanocomposites were sheeted at high temperatures in a magnetic field using a hot press. The barrier properties of prepared films, HMWPE/GnP and HMWPE/GnP-mFe₂O₃ were characterized by carrying out a permeation to oxygen experiment as a function of GnP and GnP-mFe₂O₃ contents. A decrease in gas transmission rate (GTR) was observed for the samples after being subjected to the magnetic field compared to the non-treated sample. The results of differential scanning calorimetry (DSC) and field emission electron microscopy (FESEM) experiments confirmed the orientation of GnP-mFe₂O₃ nanoparticles in nanocomposites.     

Statistical modeling of <Emphasis Type="Italic">p</Emphasis>-nitrophenol degradation using a response surface methodology (RSM) over nano zero-valent iron-modified Degussa P25-TiO<Subscript>2</Subscript>/ZnO photocatalyst with persulfate

Zero-valent iron-modified Degussa P25-TiO₂/ZnO nanocomposites (denoted as P25/Fe⁰/ZnO) were designed and prepared via Fe⁰ impregnation of P25-TiO₂/ZnO and then were employed in the visible-light photocatalytic degradation of p-nitrophenol (PNP) in the presence of [K₂S₂O₈]. Central composite design was applied for response surface modeling (RSM) to understand the influence of selected factors (pH, [Fe⁰] wt% and [K₂S₂O₈] concentration) on the degradation of PNP and to determine the interaction between the factors. The maximal PNP degradation efficiency (86.9%) was obtained with P25/1.5 wt% Fe⁰/ZnO at 3 mg/L of [K₂S₂O₈] concentration and pH 7.5. In addition, the RSM showed a satisfactory correlation between the experimental and predicted values of PNP degradation. The P25/Fe⁰/ZnO photocatalyst performance was also examined degrading methyl orange and phenol and high degradation efficiency, 82 and 99%, was achieved, respectively. The structure, morphology, light absorption and photocatalytic properties of as-prepared P25/Fe⁰/ZnO were studied using TEM, BET, XRD, FTIR and DRS.     

A study of magnetic,antibacterial and antifungal behaviour of a novel gold anchor of polyaniline/itaconic acid/Fe3O4 hybrid nanocomposite: Synthesis and characterization

The objective of the present investigation is to fabricate the gold anchor polyaniline (PANI) based nanocomposites which is prepared using itaconic acid (IA) with Fe₃O₄ by the simple polymerization reaction. The developed multi responsive antibacterial magnetic polymeric composite is represented as Au@PANI–IA–Fe₃O₄. Further, the chemical structure, thermal and magnetic properties such as FT-IR, TGA/DTA, and VSM analysis are studied. The TEM and SEM/EDX are used to find the shape and composition of gold nanoparticles. The enhanced magnetic properties of ferrite composite are exhibited and the antibacterial properties are determined using E. coli (gram -ve) and S. aureus (gram +ve) bacteria’s. The results of biological properties such as antifungal and antimicrobial are also studied critically conferred. Based on the experimental results, the fabrication method of Au@/PANI/IA/Fe₃O₄ magnetic nanocomposites, and the relationship between the structure and biological properties are discussed in detail.     

Bio‐based hyperbranched polyurethane/Fe3O4 nanocomposites as shape memory materials

The bio‐based shape memory polymers have generated immense interest as advanced smart materials. Mesua ferrea L. seed oil‐based hyperbranched polyurethane (HBPU)/Fe₃O₄ nanocomposites were prepared by the in‐situ polymerization technique. The transmission electron microscopy confirmed the homogeneous distribution of the Fe₃O₄ nanoparticles in polymer matrix, whereas Fourier transform infrared spectroscopic study revealed the presence of strong interfacial interactions between them. The incorporation of Fe₃O₄ (0 to 10 wt%) into the HBPU resulted in an increase in tensile strength (5.5–15 MPa) and scratch resistance (3–6 kg). The thermo‐gravimetric analysis indicated the improvement of thermal stability (240–270°C) of the nanocomposites. The nanocomposites exhibited full shape fixity, as well as almost full shape recovery under the microwave stimulus. The shape recovery speed increased with the increase of Fe₃O₄ nanoparticles content in the nanocomposites. Thus, the studied nanocomposites might be used as advanced shape memory materials in different potential fields. Copyright © 2013 John Wiley & Sons, Ltd.     

Coal tar residues-based nanostructured activated carbon/Fe3O4 composite electrode materials for supercapacitors

Oxygen-rich activated carbon with a three-dimensional network structure was prepared by chemical activation of coal tar residues with potassium hydroxide and subsequent carbonization treatment. Nanostructured Fe₃O₄/AC composites were then prepared by simple chemical coprecipitation method and were used as active electrode materials for supercapacitors. The electrochemical behaviors of Fe₃O₄/AC nanocomposites were characterized by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy in 1.0 M Na₂SO₃ electrolyte. It was shown that the specific capacitance of Fe₃O₄/AC nanocomposites reached 150 F g^?1 at a current density of 3.0 A g^?1 and was a great improvement over Fe₃O₄ or AC alone. Furthermore, as-prepared Fe₃O₄/AC nanocomposites exhibited long cycle life without obvious capacitance fading even after 1,000 charge/discharge cycles. Compared with pure Fe₃O₄ and AC, the significant enhanced electrochemical performance of Fe₃O₄/AC nanocomposites could be reasonably attributed to the positive synergetic effect between Fe₃O₄ and AC.     

Photocatalytic and antibacterial activities of Ag-doped ZnO thin films prepared by a sol–gel dip-coating method

Silver-doped ZnO thin films with various loadings of Ag in the range of 0–10 mol% were prepared by the sol–gel dip-coating method. All prepared films show X-ray powder diffraction patterns that matched with ZnO in its würtzite structure. The grain size decreased as the Ag loading increased. The prepared films, under UV blacklight illumination, produced a photocatalytic degradation of methylene blue, rhodamine B and reactive orange solutions. Furthermore, they inhibited the growth of Escherichia coli bacteria under UV blacklight irradiation and to a lesser extent in dark conditions. The photocatalytic and antibacterial activities of the prepared films increased with Ag loading, presumably because Ag enhanced the efficiency of generation of superoxide anion radicals (^•O₂ ⁻) and hydroxyl radicals (^•OH).     

A novel Prussian blue‐magnetite composite synthesized by self‐template method and its application in reduction of hydrogen peroxide

A novel Prussian blue (PB)‐Fe₃O₄ composite has been prepared for the first time by self‐template method using PB as the precursor. According to this method, Fe₃O₄ nanoparticles distributed uniformly on the surface of PB cube. The feed ratio of sodium acetate to PB has been proved to be a key factor for magnetic properties and electro‐catalysis properties of the composite. Under the experimental conditions, the saturation magnetization value (Ms) of PB‐Fe₃O₄–2 composite was 22 emug^?1, while the Ms value of other samples reduced. The composites also showed a good peroxidase‐like activity for the oxidation of substrate 3,3,5,5‐tetramethylbenzidine (TMB) in the presence of H₂O₂. The catalytic reduction of hydrogen peroxide capacity was PB‐Fe₃O₄–1> PB‐Fe₃O₄–2> PB‐Fe₃O₄–3> PB‐Fe₃O₄–0, which confirmed the Fe(II) centres in PB surface and Fe₃O₄ nanoparticles had synergistic effect on catalytic reduction of hydrogen peroxide.     

ZnO nanorods as efficient catalyst for the green synthesis of thiophene derivatives: Investigation of antioxidant and antimicrobial activity

In this work, thiophene derivatives were synthesized in good yields via multicomponent reaction of isoquinoline, alkyl bromides, activated acetylenic compounds, isothiocyanates, and catalytic amounts of ZnO nanorods (NRs) at room temperature under solvent-free conditions. This procedure for the synthesis of thiophene derivatives is green, easy, and simple with excellent yield. In addition, DPPH radical scavenging and ferric reduction power experiment has been studied for the evaluation of the antioxidant activity of some prepared thiophenes, for example, 5b , 5d , 5e , and 5f . As outcome, the compound 5d exhibited a noteworthy radical trapping activity and excellent reducing ability than synthetic antioxidants such as butylated hydroxytoluene (BHT) and 2-tertbutylhydroquinone (TBHQ). Moreover, the antimicrobial activity of some synthesized thiophenes was confirmed by employing the disk diffusion test on Gram-positive and Gram-negative bacteria. The obtained results of disk diffusion test showed that compounds 5b , 5d , 5e , and 5f prevented bacterial growth.     

Characterization and application of Fe3O4/SiO2 nanocomposites

A sol-gel procedure was used to cover Fe₃O₄ nanoparticles with SiO₂ shell, forming a core/shell structure. The core/shell nanocomposites were synthesized by a two-step process. First, Fe₃O₄ nanoparticles were obtained through co-precipitation and dispersed in aqueous solution through electrostatic interactions in the presence of tetramethylammonium hydroxide (TMAOH). In the second step, Fe₃O₄ was capped with SiO₂ generated from the hydrolyzation of tetraethyl orthosilicate (TEOS). The structure and properties of the formed Fe₃O₄/SiO₂ nanocomposites were characterized and the results indicate that the Fe₃O₄/SiO₂ nanocomposites are superparamagnetic and are about 30 nm in size. Bioconjugation to IgG was also studied. Finally, the mechanism of depositing SiO₂ on magnetic nanoparticles was discussed.     

Conducting and magnetic behaviors of monodispersed iron oxide/polypyrrole nanocomposites synthesized by in situ chemical oxidative polymerization

This study describes the preparation of nanocomposites fabricated from monodispersed iron oxide (Fe₃O₄) and polypyrrole (PPy) by in situ chemical oxidative polymerization. The monodispersed 4 nm Fe₃O₄ nanoparticles which served as cores were synthesized using the thermal decomposition of a mixture of Iron (III) acetylacetonate and oleic acid in the presence of high boiling point solvents. The resulting nanoparticles were further dispersed in an aqueous solution with anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate to form micelle/Fe₃O₄ spherical templates that avoid the aggregation of Fe₃O₄ nanoparticles during the further preparation of the nanocomposites. The Fe₃O₄/PPy nanocomposites were then synthesized via in situ chemical oxidative polymerization on the surface of the spherical templates. Both field‐emission scanning electron microscopy (FESEM) and high‐resolution transmission electron microscopy (HRTEM) images indicate that the resulting Fe₃O₄ nanoparticles are close to spherical dots with a particle size of about 4 nm and a standard deviation of less than 5% (4 ± 0.2 nm). Structural and morphological analysis using FESEM and HRTEM showed that the fabricated Fe₃O₄/PPy nanocomposites are core (Fe₃O₄)‐shell (PPy) structures. Morphology of the nanocomposites shows a remarkable change from spherical to tube‐like structures as the content of monodispersed Fe₃O₄ nanoparticles increases from 9% up to 24 wt %. The conductivities of these Fe₃O₄/PPy nanocomposites are about six times higher than those of PPy without Fe₃O₄. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4647–4655, 2007     

Synthesis and characterisation of magnetic activated carbon/diopside nanocomposite for removal of reactive dyes from aqueous solutions: experimental design and optimisation

In this work, a series of magnetic activated carbon/nanodiopside (Fe₃O₄/AC/Diop) nanocomposites were synthesised and used for the removal of reactive green KE-4BD dye from the aqueous solution. After preparation of nanodiopside by sol-gel method and activated carbon from coconut husk, first, Fe₃O₄/AC composite was prepared by in situ synthesis of Fe₃O₄ nanoparticles between activated carbon pores, and then, different percentages of Fe₃O₄/AC/Diop nanocomposites were prepared by simple mixing of Fe₃O₄/AC composite and Diop in ethanol. Formation of Fe₃O₄/AC and Fe₃O₄/AC/Diop composites was characterised by FTIR, field emission scanning electron microscopy, BET, XRD and vibrating sample magnetometer analyses. Thermogravimetric analysis was used to show the adsorption capacity of the adsorbent more accurately. Effects of amount of adsorbent, initial pH, contact time and dye concentration on reactive green dye removal were also studied using central composite design. Optimal conditions for maximum reactive green KE-4BD dye adsorption (98.35%) process were as follows: pH= 4.90, adsorbent amount: 0.015 g, dye concentration: 37.17 mg/L and contact time: 10.12 min, respectively. In addition, the adsorption kinetics, thermodynamics and isotherms were examined. Adsorption isotherms (q_max: 344.827 mg/g), kinetics and thermodynamics were demonstrated that the sorption processes were better described by the pseudo-second-order equation and the Langmuir equation.     

Effect of polyol structure on the properties of the resultant magnetic polyurethane elastomer nanocomposites

In this study, two types of magnetic polyurethane (PU) elastomer nanocomposites using polycaprolactone (PCL) and polytetramethylene glycol (PTMG) as polyols were synthesized by incorporating thiodiglycolic acid surface modified Fe₃O₄ nanoparticles (TSM‐Fe₃O₄) into PU matrices through in situ polymerization method. TSM‐Fe₃O₄ nanoparticles were prepared using in situ coprecipitation method in alkali media and were characterized by X‐ray diffraction, Fourier Transform Infrared Spectrophotometer, Transmission Electron Microscopy, and Vibrating Sample Magnetometer. The effects of PCL and PTMG polyols on the properties of the resultant PUs were studied. The morphology and dispersion of the nanoparticles in the magnetic nanocomposites were studied by Scanning Electron Microscope. It was observed that dispersion of nanoparticles in PTMG‐based magnetic nanocomposite was better than PCL‐based magnetic nanocomposite. Furthermore, the effect of polyol structure on thermal and mechanical properties of nanocomposite was investigated by Thermogravimetric Analysis and Dynamic Mechanical Thermal Analysis. A decrease in the thermal stability of magnetic nanocomposites was found compared to pure PUs. Furthermore, DMTA results showed that increase in glass transition temperature of PTMG‐based magnetic nanocomposite is higher than PCL‐based magnetic nanocomposite, which is attributed to better dispersion of TSM‐Fe₃O₄ nanoparticles in PTMG‐based PU matrix. Additionally, magnetic nanocomposites exhibited a lower level of hydrophilicity compared to pure PUs. These observations were attributed to the hydrophobic behavior of TSM‐Fe₃O₄ nanoparticles. Moreover, study of fibroblast cells interaction with magnetic nanocomposites showed that the products can be a good candidate for biomedical application. Copyright © 2013 John Wiley & Sons, Ltd.