Finite element simulation for the effect of loading rate on visco‐hyperelastic characterisation of soft materials by spherical nanoindentation

Nanoindentation test performed by atomic force microscopy is highly recommended for the characterisation of soft materials at nanoscale. The assumption proposed in the characterisation is that the material is pure elastic with no viscosity. However, this assumption does not represent the real characteristics of soft materials such as bio tissue or cell. Therefore, a parametric finite element simulation of nanoindentation by spherical tip was carried out to investigate the response of cells with different constitutive laws (elastic, hyperelastic and visco‐hyperelastic). The investigation of the loading rate effect on the characterisation of cell mechanical properties was performed for different size of spherical tip. The selected dimensions of spherical tips cover commercially available products. The viscosity effects are insensitive to the varied dimensions of spherical tip in this study. A limit loading rate was found above which viscous effect has to be considered to correctly determine the mechanical properties. The method in this work can be implemented to propose a criterion for the threshold of loading rate when viscosity effect can be neglected for soft material characterisation.Inspec keywords: atomic force microscopy, viscoelasticity, finite element analysis, nanoindentation, viscosity, biomechanics, indentation, elasticityOther keywords: spherical tip, viscosity effect, viscous effect, soft material characterisation, visco‐hyperelastic characterisation, spherical nanoindentation, nanoindentation test, atomic force microscopy, bio tissue, parametric finite element simulation, loading rate effect, cell mechanical properties, constitutive laws     

Self‐repair behaviour of the neuronal cell membrane by conductive atomic force indentation

Conductive atomic force indentation (CAFI) was proposed to study the self‐repair behaviour of the neuronal cell membrane here. CAFI was used to detect the changes of membrane potentials by performing the mechanical indentation on neurons with a conductive atomic force microscope. In the experiment, a special insulation treatment was made on the conductive probe, which turned out to be a conductive nanoelectrode, to implement the CAFI function. The mechanical properties of the neuronal cell membrane surface were tested and the membrane potential changes of neurons cultured in vitro were detected. The self‐repair behaviour of the neuronal cell membrane after being punctured was investigated. The experiment results show that CAFI provides a new way for the study of self‐repair behaviours of neuronal cell membranes and mechanical and electrical properties of living cells.Inspec keywords: neurophysiology, bioelectric potentials, indentation, membranes, biomembranes, probes, cellular biophysics, atomic force microscopyOther keywords: CAFI, self‐repair behaviour, membrane potentials, neurons, conductive atomic force microscope, conductive probe, conductive nanoelectrode, neuronal cell membrane surface, membrane potential changes, conductive atomic force indentation     

Investigation of the morphological cell structures and their optical significances of Aeshna cyanea

The transparent wing of the dragonfly Aeshna cyanea has been investigated using scanning electron microscopy (SEM), optical microscopy (OPM), energy‐dispersive X‐ray spectroscopy (EDS) and reflectance spectroscopy. Four cells (D1–D4) were studied and classified according to their general morphology. The OPM depicted the vein‐joint characterised by the distribution of resilin. EDS technique showed common elements such as carbon, oxygen, and chlorine. SEM analysis revealed thin membranes reinforced with a network of hallow veins. Spikes and round shape of microstructures were identified. The roughness of the pruinosity was estimated, which indicates the shape and curvature of the microstructures that essentially play a significant role in the optical response observed. The study can be essential to design and improve micro‐air vehicles.Inspec keywords: bio‐optics, optical microscopy, biomembranes, light reflection, X‐ray chemical analysis, scanning electron microscopy, crystal microstructureOther keywords: transparent wing, EDS technique, SEM analysis, morphological cell structures, optical microscopy, dragonfly Aeshna cyanea, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, reflectance spectroscopy, vein‐joint characterization, resilin distribution, carbon, oxygen, chlorine, thin membrane reinforced hallow vein network, microstructure spikes, microstructure round shape, micro‐air vehicles     

Antibacterial activity of carbon nanoparticles isolated from chimney soot

Carbon nanoparticles (CNPs) are isolated from chimney soot and characterised by various tools such as X‐ray diffraction, scanning electron microscopy, transmission electron microscopy and ultraviolet–visible spectroscopy. The X‐ray diffraction studies confirm the presence of C₆₀ nanoparticles in the isolated sample. The thermal properties of the prepared CNPs are recorded using thermogravimetric analysis and differential thermal analysis. The analysis of the antibacterial activity of the synthesised CNPs against selected Gram‐positive and Gram‐negative bacterial strains is also investigated. The systematic study confirms that CNPs collected from chimney soot exhibit good antibacterial potency against Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumoniae, and Proteus mirabilis.Inspec keywords: ultraviolet spectra, scanning electron microscopy, visible spectra, differential thermal analysis, thermal analysis, antibacterial activity, nanoparticles, X‐ray diffraction, nanofabrication, transmission electron microscopy, carbonOther keywords: chimney soot, transmission electron microscopy, ultraviolet–visible spectroscopy, thermal properties, thermogravimetric analysis, differential thermal analysis, antibacterial activity, carbon nanoparticles, X‐ray diffraction study, gram‐positive bacterial strains, gram‐negative bacterial strains, antibacterial potency, scanning electron microscopy, C₆₀      

Biocompatibility enhancement of graphene oxide‐silver nanocomposite by functionalisation with polyvinylpyrrolidone

Several materials such as silver are used to enhance graphene oxide (GO) sheets antimicrobial activity. However, these toxic materials decrease its biocompatibility and hinder its usage in many biological applications. Therefore, there is an urgent need to develop nanocomposites that can preserve both the antimicrobial activity and biocompatibility simultaneously. This work highlights the importance of functionalisation of GO sheets using Polyvinylpyrrolidone (PVP) and decorating them with silver nanoparticles (AgNPs) in order to enhance their antimicrobial activity and biocompatibility at the same time. The structural and morphological characterisations were performed by UV‐Visible, Fourier transform infrared (FTIR), and Raman spectroscopic techniques, X‐ray diffraction (XRD), and high‐resolution transmission electron microscopy (HR‐TEM). The antimicrobial activities of the prepared samples against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans were studied. The cytotoxicity of prepared materials was tested against BJ1 normal skin fibroblasts. The results indicated that the decoration with AgNPs showed a significant increase in the antimicrobial activity of GO and FGO sheets, and functionalisation of GO sheets and GO‐Ag nanocomposite with PVP improved the cell viability about 40 and 35%, respectively.Inspec keywords: biomedical materials, nanocomposites, visible spectra, ultraviolet spectra, X‐ray diffraction, cellular biophysics, nanoparticles, Raman spectra, filled polymers, transmission electron microscopy, silver, microorganisms, antibacterial activity, nanomedicine, nanofabrication, graphene compounds, toxicology, Fourier transform infrared spectraOther keywords: graphene oxide‐silver nanocomposite, polyvinylpyrrolidone, toxic materials, biocompatibility, antimicrobial activity, morphological characterisations, structural characterisations, UV‐visible spectra, Fourier transform infrared spectra, Raman spectra, X‐ray diffraction, high‐resolution transmission electron microscopy, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, cytotoxicity, BJ1 normal skin fibroblasts, cell viability, CO‐Ag     

Antibacterial and anticancer activity of biosynthesised CuO nanoparticles

The present investigation aims for the synthesis of copper oxide nanoparticles (CuO NPs) using Nilgirianthus ciliatus plant extract. The obtained CuO NPs were characterised by X‐ray diffraction, Fourier transform infrared spectrum, ultraviolet–visible spectroscopy, photoluminescence, scanning electron microscopy and transmission electron microscopy analysis. Significant bacterial activity was manifested by CuO nanoparticles against both Gram‐positive (Staphylococcus aureus and Staphylococcus mutans) and Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. The synthesised CuO NPs have good cytotoxicity against both human breast cancer cell line (MCF‐7) and lung cancer cell line (A549) with minimum cytotoxic effect on normal L929 (fibroblast) cell lines.Inspec keywords: microorganisms, ultraviolet spectra, nanomedicine, transmission electron microscopy, visible spectra, cellular biophysics, antibacterial activity, nanoparticles, X‐ray diffraction, lung, copper compounds, cancer, toxicology, biomedical materials, scanning electron microscopy, photoluminescence, Fourier transform infrared spectraOther keywords: antibacterial activity, anticancer activity, biosynthesised CuO nanoparticles, copper oxide nanoparticles, Nilgirianthus ciliatus plant, X‐ray diffraction, infrared spectrum, ultraviolet–visible spectroscopy, transmission electron microscopy analysis, bacterial activity, Gram‐negative bacteria, synthesised CuO NPs, human breast cancer cell line, Staphylococcus aureus, Staphylococcus mutans, CuO     

Estimation of skin impedance models with experimental data and a proposed model for human skin impedance

The skin is a complex biological tissue whose impedance varies with frequency. The properties and structure of skin changes with the location on the body, age, geographical location and other factors. Considering these factors, skin impedance analysis is a sophisticated data analysis. However, despite all these variations, various researchers have always worked to develop an equivalent electrical model of the skin. The two most important categories of electrical models are RC‐based model and CPE‐based model which focus on the physiological stratification and biological properties of skin, respectively. In this work, experimental skin impedance data is acquired from ten sites on the body to find the fitting model. It is observed that a hybrid of fractional‐order CPE‐based model and higher‐order RC layered‐based model can provide the best fitting electrical model of skin. A new model is developed with this hybrid orders. Genetic algorithm is used for the extraction of parameter components. Least error of fitting has been observed for the proposed model as compared with the other models. This model can be used in correlating many skin problems and in the development of diagnostic tools. It will offer an additional supportive tool in‐vitro to the medical specialist.Inspec keywords: genetic algorithms, skin, data analysis, bioelectric phenomena, medical computing, electric impedance, patient diagnosisOther keywords: skin impedance models, human skin impedance, skin impedance analysis, data analysis, electrical models, RC‐based model, biological properties, experimental skin impedance data, fractional‐order CPE‐based model, skin problems, complex biological tissue, higher‐order RC layered‐based model, genetic algorithm, diagnostic tools     

Fabrication and characterisation of super‐paramagnetic responsive PLGA–gelatine–magnetite scaffolds with the unidirectional porous structure: a physicochemical,mechanical, and in vitro evaluation

Architecture and composition of Scaffolds are influential factors in the regeneration of defects. Herein, synthesised iron oxide (magnetite) nanoparticles (MNPs) by co‐precipitation technique were evenly distributed in polylactic‐co‐glycolic acid (PLGA)–gelatine Scaffolds. Hybrid structures were fabricated by freeze‐casting method to the creation of a matrix with tunable pores. The synthesised MNPs were characterised by transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction spectroscopy, and vibrating sample magnetometer analysis. Scanning electron microscopy micrographs of porous Scaffolds confirmed the formation of unidirectional microstructure, so that pore size measurement indicated the orientation of pores in the direction of solvent solidification. The addition of MNPs to the PLGA–gelatine Scaffolds had no particular effect on the morphology of the pores, but reduced slightly pore size distribution. The MNPs contained constructs demonstrated increased mechanical strength, but a reduced absorption capacity and biodegradation ratio. Stability of the MNPs and lack of iron release was the point of strength in this investigation and were determined by atomic absorption spectroscopy. The evolution of rat bone marrow mesenchymal stem cells performance on the hybrid structure under a static magnetic field indicated the potential of super‐paramagnetic constructs for further pre‐clinical and clinical studies in the field of neural regeneration.Inspec keywords: transmission electron microscopy, biodegradable materials, nanofabrication, freezing, mechanical strength, tissue engineering, X‐ray diffraction, cellular biophysics, precipitation (physical chemistry), biomedical materials, iron compounds, porosity, scanning electron microscopy, atomic absorption spectroscopy, gelatin, nanoparticles, porous materials, bone, nanocomposites, Fourier transform infrared spectraOther keywords: unidirectional microstructure, pore size measurement, mechanical strength, atomic absorption spectroscopy, hybrid structure, super‐paramagnetic responsive PLGA–gelatine–magnetite scaffolds, unidirectional porous structure, tissue engineering Scaffolds, co‐precipitation technique, polylactic‐co‐glycolic acid–gelatine Scaffolds, freeze‐casting method, transmission electron microscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction spectroscopy, scanning electron microscopy micrographs, pore size distribution, absorption capacity, iron oxide nanoparticles, Fe₃ O₄      

Properties of scaffolds based on chitosan and collagen with bioglass 45S5

Scaffolds based on chitosan (CTS), collagen (Coll) and glycosaminoglycans (GAG) mixtures cross‐linked by tannic acid (TA) with bioglass 45S5 addition were obtained with the use of the freeze‐drying method. The prepared scaffolds were characterised for morphology, mechanical strength and degradation rate. Moreover, cell viability on the obtained scaffolds was measured with and without the presence of ascorbic acid and dexamethasone. The main purpose of the research was to compare the effectiveness of bioglass 45S5 influence on the physicochemical and biological properties of scaffolds. The results demonstrated that the scaffolds based on the blends of biopolymers cross‐linked by TA are stable in an aqueous environment. Scanning electron microscope images allowed the observation of a porous scaffold structure with interconnected pores. The addition of bioglass nanoparticles improved the mechanical properties and decreased the degradation rate of composite materials. The biological properties were improved for 20% tannic acid addition compared to 5%. However, the addition of bioglass 45S5 did not change to cells response significantly.Inspec keywords: biomedical materials, drying, porous materials, freezing, tissue engineering, proteins, nanofabrication, bone, scanning electron microscopy, polymers, molecular biophysics, cellular biophysics, nanoparticles, porosityOther keywords: chitosan, collagen, glycosaminoglycans, bioglass 45S5 addition, freeze‐drying method, degradation rate, ascorbic acid, dexamethasone, physicochemical properties, biological properties, porous scaffold structure, bioglass nanoparticles, mechanical properties, tannic acid addition, scanning electron microscopy     

Cytotoxicity properties of functionalised carbon nanotubes on pathogenic bacteria

Nanobiotechnology is a promising field concerned with the using of engineered nanomaterials, which leads to the improvement of new human remedial against pathogenic bacteria modalities. In this work, silver nanoparticles (AgNPs) were prepared by an easy, cheap and low‐cost electro‐chemical method. The AgNPs were then loaded successfully on to multi‐walled carbon nanotubes (MWCNTs) using a modified chemical reaction process. The AgNPs on the MWCNTs were well spread and evenly distributed on the surfaces of the long nanotubes with well‐graphitised walls as examined by high‐resolution transmission electron microscopy. X‐ray diffraction and transmission electron microscopy were used for sample characterisation. Good dispersion of AgNPs was obtained on the surface of MWCNTs, resulting in an efficient reactivity of the carbon nanotubes surfaces. Finally, the antibacterial activity of AgNPs/MWCNTs hybrid was evaluated against two pathogenic bacteria Pseudomonas aeruginosa and Staphylococcus aureus exhibited excellent activity.Inspec keywords: nanocomposites, X‐ray diffraction, nanofabrication, nanoparticles, transmission electron microscopy, toxicology, silver, antibacterial activity, microorganisms, nanomedicine, multi‐wall carbon nanotubes, electrochemistryOther keywords: engineered nanomaterials, human remedial, pathogenic bacteria modalities, silver nanoparticles, multiwalled carbon nanotubes, modified chemical reaction process, well‐graphitised walls, high‐resolution transmission electron microscopy, cytotoxicity properties, functionalised carbon nanotubes, carbon nanotube surfaces, nanobiotechnology, low‐cost electrochemical method, AgNP‐MWCNT hybrid, X‐ray diffraction, antibacterial activity, Pseudomonas aeruginosa, Staphylococcus aureus, Ag‐C     

Relative larvicidal property of common oxide nanostructures against Culex quinquefasciatus

Common oxide nanostructures such as silicon‐di‐oxide, magnesium‐oxide, zinc‐oxide, and copper‐oxide (CuO) having useful functional and bioactive properties have been synthesised and characterised. All these nanostructures have been found to be larvicidal towards Culex quinquefasciatus mosquito especially against lower instars in comparison with higher instars in 48 h. Only, CuO is larvicidal against late instar stages after 48 h. Moreover, CuO is larvicidal against first instar stages after 24 h (LC₅₀ 157 mg/l). However, none of these nanostructures are pupicidal. Post mortality larval morphology was found to be distorted under bright field microscopy and scanning electron microscopy images of affected larval surface appeared to be rough and uneven. Fluorescent images showed that nanostructures infiltrated inside visceral organs of larvae. Nanostructures also caused tissue oxidative stress in larvae. These results indicate that above stated oxide nanostructures are effective larvicidal agents against early instar stages of Culex larvae.Inspec keywords: biodegradable materials, oxidation, optical microscopy, fluorescence, cellular biophysics, biological tissues, diseases, scanning electron microscopy, toxicology, biological techniquesOther keywords: late instar stages, bright field microscopy, scanning electron microscopy images, tissue oxidative stress, oxide nanostructures, silicon‐dioxide, magnesium‐oxide, zinc‐oxide, copper‐oxide, functional properties, bioactive properties, larvicidal property, larvicidal agents, Culex quinquefasciatus mosquito, Culex larvae     

Novel synthesis of ultra‐fine Sb2 O3 nanocubes using plant extract

In this study, the synthesis of ultra‐fine grade antimony trioxide (Sb₂ O₃) using plant extract for the first time is reported. Antimony chloride was used as a starting material and Dioscorea alata tuber extract was used as a reducing and capping agent. The synthesised nanoparticles were characterised by X‐ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy. XRD analysis indicates the formation of pure Sb₂ O₃ nanoparticles. The result from FE‐SEM and DLS showed that the particles have a cube‐like morphology and have an average size of 346.4 nm which falls within the range of ultra‐fine grade Sb₂ O₃.Inspec keywords: field emission electron microscopy, scanning electron microscopy, X‐ray diffraction, particle size, nanofabrication, light scattering, transmission electron microscopy, ultraviolet spectra, nanoparticles, antimony compounds, Fourier transform infrared spectraOther keywords: field emission scanning electron microscopy, FE‐SEM, dynamic light scattering, DLS, XRD analysis, antimony chloride, starting material, reducing agent, ultrafine grade antimony trioxide, plant extract, dioscorea alata tuber extract, capping agent, X‐ray diffraction, pure antimony trioxide nanoparticles, cube‐like morphology, Sb₂ O₃      

Promising opportunities and potential risk of nanoparticle on the society

The ever‐promising opportunities and the uses of NP in our life are increasing but their present and future potential risks on the animals, plants and microorganisms are not well discussed elsewhere. In this review, the authors have systematically discussed the toxic effect of the uses of NP on animals, plants and microorganisms including human health. They have also discussed about the bioaccumulation of these NP in the food chain. Finally, they have provided some possible suggestions for the uses of NP to reduce the detrimental effect on the environment.Inspec keywords: nanoparticles, health and safety, toxicology, microorganismsOther keywords: ever‐promising opportunities, plants, microorganisms, toxic effect, human health, nanoparticle, food chain, bioaccumulation     

Extracellular biosynthesis of biocompatible CdSe quantum dots

An extracellular biosynthesis method has been developed to prepare cadmium selenide (CdSe) quantum dots (QDs) with strong fluorescence emission by incubating cheap Cd and Se inorganic salts with Escherichia coli (E.coli) bacteria. Ultraviolet–visible absorption spectra, photoluminescence (PL) spectra, and high‐resolution transmission electron microscopy analysis showed that the biosynthesised CdSe QDs have an average size of 3.1 nm, the excellent optical properties with fluorescence emission around 494 nm, and the good crystallinity. It was found that addition of 80 mg of mercaptosuccinic acid resulted in the formation of CdSe QDs with highest PL intensity. Furthermore, Fourier‐transform infrared spectra of as‐synthesised CdSe QDs confirmed the presence of a surface protein capping layer. The biosynthesised CdSe QDs were incorporated into the yeast cells as illustrated by laser confocal scanning microscopy images, showing a great potential in bio‐imaging and bio‐labelling application.Inspec keywords: microorganisms, molecular biophysics, fluorescence, visible spectra, nanofabrication, nanobiotechnology, proteins, cellular biophysics, nanostructured materials, wide band gap semiconductors, cadmium compounds, semiconductor quantum dots, II‐VI semiconductors, transmission electron microscopy, photoluminescence, optical microscopy, ultraviolet spectra, Fourier transform infrared spectra, biological techniques, semiconductor growthOther keywords: biocompatible CdSe quantum dots, extracellular biosynthesis method, cadmium selenide quantum dots, high‐resolution transmission electron microscopy analysis, biosynthesised CdSe QDs, Fourier‐transform infrared spectra, Escherichia coli, ultraviolet‐visible absorption spectra, PL intensity, fluorescence emission, photoluminescence spectra, optical properties, surface protein capping layer, laser confocal scanning microscopy images, bioimaging, biolabelling application, yeast cells, f mercaptosuccinic acid, CdSe     

Biosynthesis of Ag nanoparticles and two‐dimensional element distribution in Arabidopsis

Metallic nanoparticles can be synthesised in living plants, which provide a friendly approach. In this work, the authors aimed to study the synthesis of silver nanoparticles (AgNPs) in Arabidopsis and the two‐dimensional (2D) distribution of Ag and other elements (Ca, P, S, Mg, and CI) in the Arabidopsis plant tissues. The concentrations of Ag in the plant tissues were determined by inductively coupled plasma‐atomic emission spectrometer, showing that the majority of Ag was retained in the roots. Transmission electron micrographs showed the morphology of AgNPs and the location in plant cells. The distributions of Cl and Ag were consistent in plant tissues by 2D proton‐induced X‐ray emission. In conclusion, this is the first report of the AgNP synthesis in Arabidopsis living plants and its 2D distribution of important elements, which provide a new clue for further research.Inspec keywords: silver, botany, atomic emission spectroscopy, antibacterial activity, nanoparticles, nanofabrication, transmission electron microscopy, chlorine, calcium, sulphur, phosphorusOther keywords: biosynthesis, two‐dimensional element distribution, metallic nanoparticles, silver nanoparticles, Arabidopsis plant tissues, inductively coupled plasma‐atomic emission spectrometry, transmission electron micrography, plant cells, 2D proton‐induced X‐ray emission, Arabidopsis living plants, Ag, Cl, Ca, P, S, Mg     

Synthesised magnetic nano‐zeolite as a mycotoxins binder to reduce the toxicity of aflatoxins,zearalenone, ochratoxin A,and deoxynivalenol in barley

Agricultural commodities, particularly cereals can be contaminated with mycotoxins during the pre‐ and post‐harvest stage. The main goal of this study was to evaluate the efficacy of magnetic zeolite nanocomposite (MZNC) as an adsorbent for the reduction of mycotoxins in barley flour. The MZNC is synthesised using an eco‐friendly and efficient procedure and characterised by zeta potential, field emission scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. The adsorbent amount that affects the adsorption capacity was optimised. Low amounts of the nanocomposite removed >99% of aflatoxins, 50% of ochratoxin A, 22% of zearalenone, and 1.8% of the deoxynivalenol from the contaminated sample and adsorption by MZNC was better than the natural zeolite; this phenomenon is related to the wide surface of nanocomposites. Results provide new insights into possible future research that could overcome the challenges of using nanotechnology to eliminate mycotoxins from agricultural products. It can be hoped that the presence of cheap and eco‐friendly mycotoxin binders such as the MZNC that is synthesised and utilised in this research will help to produce secure food and feed products.Inspec keywords: toxicology, field emission electron microscopy, zeolites, scanning electron microscopy, adsorption, X‐ray chemical analysis, nanotechnology, nanocomposites, agricultural products, contaminationOther keywords: synthesised magnetic nanozeolite, mycotoxins binder, zearalenone, deoxynivalenol, ochratoxin A, agricultural commodities, cereals, post‐harvest stage, magnetic zeolite nanocomposite, MZNC, barley flour, zeta potential field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, adsorption capacity, natural zeolite, agricultural products, eco‐friendly mycotoxin binders, aflatoxins, toxicity     

Impartation of apatite‐forming ability to chitosan nanofibres by using apatite nuclei

Chitosan nanofibre–apatite nuclei composites obtained by mixing apatite nuclei which possess high apatite‐forming ability with chitosan nanofibre have been expected to be novel bone restorative materials with suitable properties such as light weight, low coefficient of thermal expansion, high mechanical strength, biocompatibility and bioactivity. In this study, the authors prepared three types of apatite nuclei by changing the reaction time aimed to optimise their crystallinity and fabricated their composites with chitosan nanofibre. In order to evaluate the bioactivity in vitro, the authors tested apatite‐forming ability in simulated body fluid. As a result, the materials showed enough apatite‐forming ability in a short time by mixing chitosan nanofibre and apatite nuclei with extremely low crystallinity and their high reactivity in simulated body fluid.Inspec keywords: calcium compounds, nanofibres, bioceramics, bone, polymer fibres, nanocomposites, filled polymers, nanomedicine, nanofabricationOther keywords: apatite‐forming ability, chitosan nanofibre‐apatite nuclei composites, bone restorative materials, reaction time, crystallinity, in vitro bioactivity, simulated body fluid, Ca₁₀ (PO₄)₆ (OH)₂      

Facile synthesis of mesoporous alumina using hexadecyltrimethylammonium bromide (HTAB) as template: simplified sol‐gel approach

Herein the authors present the synthesis of surface functionalised mesoporous alumina (MeAl) for textural characterisation by a simplified sol–gel method obtained by using hexadecyltrimethylammonium bromide as a template. Etoricoxib (ETOX) was used as a model drug for the study. Alumina supported mesoporous material containing drug was characterised using instrumental technique namely Brunauer–Emmett–Teller surface area, Fourier transform‐infrared, differential scanning calorimetry, transmission electron microscopy, X‐ray diffraction, and field emission scanning electron microscopy. Diffusion study using a dialysis bag method used to check the release pattern of ETOX‐loaded‐MeAl. Results of characterisation study revealed the successful surface functionalisation of the drug on nanocomposite. The IC₅₀ value obtained from cell viability study demonstrated the non‐toxic behaviour of synthesised drug‐loaded mesoporous alumina up to the tested concentration range. The present work has demonstrated that synthesised MeAl showed excellent stability with an expanded surface area suitable for carrier material for drug delivery system.Inspec keywords: Fourier transform spectra, adsorption, biomedical materials, silicon compounds, drug delivery systems, X‐ray diffraction, alumina, differential scanning calorimetry, nanocomposites, field emission electron microscopy, nanofabrication, nanomedicine, mesoporous materials, transmission electron microscopy, sol‐gel processing, scanning electron microscopyOther keywords: ETOX‐loaded‐MeAl, successful surface functionalisation, synthesised drug‐loaded mesoporous alumina, synthesised MeAl, expanded surface area, drug delivery system, hexadecyltrimethylammonium bromide, sol‐gel approach, surface functionalised mesoporous alumina, simplified sol–gel method, mesoporous material containing drug, Brunauer–Emmett–Teller surface area, Fourier transform‐infrared, differential scanning calorimetry, transmission electron microscopy, X‐ray diffraction, field emission scanning electron microscopy, dialysis bag method     

Comprehensive analysis of retroreflection in Papilio crino Fabricius, 1792 wings

Multilayer thin‐film structures in the wings of a butterfly; Papilio crino produce a colourful iridescence from reflected light. In this investigation, scanning electron microscope images show both the concave cover scales and pigmented air‐chamber ground scales. The microstructures with the concavities retroreflect incident light, thus causing the double reflection. This gives rise to both the colour mixing and polarisation conversion clearly depicted in the optical images. The result of the numerical and theoretical analysis via the CIELAB, and optical reflection and transmission of light through the multilayer stacks with the use of transfer method show that the emerging colouration on the Papilio crino is structural and is due to the combination of colours caused by multiple bounces within the concavities. The butterfly wing structure can be used as the template for designing the photonic device.Inspec keywords: bio‐optics, scanning electron microscopy, photodiodes, optical sensors, optical images, light reflection, reflectivity, colour, optical links, multilayers, optical multilayers, light polarisationOther keywords: pigmented air‐chamber ground scales, concavities, incident light, double reflection, colour mixing, polarisation conversion, optical images, numerical analysis, theoretical analysis, optical reflection, multilayer stacks, emerging colouration, butterfly wing structure, papilio crino fabricius, thin‐film structures, colourful iridescence, reflected light, electron microscope images, concave cover scales     

Enhancing data rate of molecular communication system using Brownian motion

Inter‐symbol and co‐channel interferences restrict the capacity of molecular communication (MC) systems. In this study, the effect of these interferences on the data rate of MC systems is investigated to design an efficient MC system. To this end, the authors propose an analytical model for a diffusion‐based MC system comprised of two nanomachines when they exploit On/Off keying modulation. They model the Brownian motion of molecules in a one‐dimensional environment as a wiener process and the life expectancy of diffused molecules as an exponential process. First, they consider the inter‐symbol interference to derive the data rate of the MC system as a function of the receiver decision threshold and the symbol time duration. Hence, they propose an algorithm to obtain the optimal values of MC system parameters. Then, the effect of co‐channel interference is considered by assuming parallel MC systems. They propose a minimum distance between adjacent MC systems that their co‐channel interferences effect to be negligible. Moreover, they verify the accuracy of the analytical results by Monte–Carlo simulations. Results show a remarkable improvement in the data rate of MC systems. The derived results may find application in nanonetworks where nanomachines connect together to perform complex tasks.Inspec keywords: channel capacity, Monte Carlo methods, intersymbol interference, stochastic processes, Brownian motion, cochannel interferenceOther keywords: enhancing data rate, molecular communication system, Brownian motion, co‐channel interference, efficient MC system, diffusion‐based MC system, inter‐symbol interference, MC system parameters, parallel MC systems, adjacent MC systems, co‐channel interferences effect