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This contribution reports on the biosynthesis of Nanoscaled Zinc oxide nanoparticles (ZnO-NPs) using natural extracts from various parts of the Moringa Oleifera as effective chelating agents. More precisely, natural extracts from flowers, seeds and leaves of Moringa Oleifera as chelating and/or oxidizing/reducing agents of zinc nitrate hexahydrate are reported for the first time in the current literature. The structural and optical properties of ZnO-NPs obtained by the leaves are slightly different from those obtained with the other extracts. The average crystallite sizes of ZnO-NPs calculated via X-rays diffraction analysis are found to be 13.2, 13.9, and 10.8 nm for ZnO-NPs synthesized by the flowers, seeds, and leaves respectively while the direct band gap values deducted from Tauc approximation are 3.12, 3.18 and 3.25 eV. From the photoluminescence analysis at room temperature, a broad band in the visible centered around 450 nm is obtained for all the zinc oxide nanoparticles. One major bioactive compound for each solution extract was used to propose a mechanism of the reaction of ZnO-NPs formation: L-ascorbic acid for the leaves, quercetin for the flowers and oleic acid for the seeds.

This work reports for the first time the possibility of green synthesis and the antibacterial effect of silver nanoparticles (AgNPs) on commercialized polycarbonate membrane. The AgNPs were loaded on the polycarbonate membrane serving as the substrate via ultra-sonication and centrifugation. The extracts from the red flowers of Callistemon viminalis were used as the chelating agent. The synthesised thin film silver nanoparticles were characterized by various techniques such as Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX), Fourier transform-infrared (FT-IR), X-Ray diffraction and UV–Vis spectroscopy. Consequently, the antibacterial affect was studied. The synthesised thin film silver nanoparticles had a surface plasmon resonance of 310nmand show a very effective inhibition growth of both Gram-positive and Gram-negative.

Graphene, a single layer graphitic based material, is nowadays the most promising and studied material due to its unique physical and chemical properties [1]. The “top-down” method of synthesizing graphene from graphene oxide (GO) by chemical reduction is the most economical and efficient method. Oxygen based components of GO, such as epoxide, carbonyl, carboxyl and hydroxyl groups have to be eliminated, as much as possible to be more closed to a monomolecular layer of graphite. However, chemical reducing agents, such as hydrazine, are harsh and environmentally unfriendly to be used for large scale production [8]. Madagascar has great varieties of indigenous plants, some of them have a power to heal illness and cancers [16], and used as herbal medicine by traditional health practitioners. This study will complete all reports done on bio-synthesis of graphene by green chemistry process [1]. Hence, physical and optical properties of the obtained graphene sheets mediated by Catharanthus roseus (CR), Phyllarthron madagascariense K. Schum (PM), Cinnamomum camphora cineoliferum (CCC), Cedrelopsis grevei Baill (CGB) and Artemisia annua (AA) natural extracts are reported on this work. Optical and physical properties of the obtained graphene sheets through Raman shift and X-Ray diffraction spectroscopy, confirmed the reduction and conversion of the bulk graphitic material to few-layered reduced graphene oxide. Hence, bio-active compounds extracted from Catharanthus roseus (CR), Phyllarthron madagascariense K. Schum (PM), Cinnamomum camphora cineoliferum (CCC), Cedrelopsis grevei Baill (CGB) and Artemisia annua (AA), can be used and are effective chelating agent for the synthesizing of graphene sheets.

Cadmium oxide (CdO) nanoparticles were synthesized for the first time via an eco-friendly, simple and cost effective green synthesis method mediated by corn husk extract. Indeed, the corn husk extract acted as an effective chelating agent in facilitating the formation of the CdO nanoparticles. XRD analysis confirmed the formation of highly crystalline face-centred cubic CdO nanoparticles. The structural morphology and the constituents of the resultant CdO nanoparticles were investigated by High Resolution – Scanning Electron Microscopy (HR-SEM) and Energy Dispersive X- rays Spectroscopy (EDS). Attenuated Total Reflection – Fourier Transformer Infrared spectroscopy (ATR-FTIR) and Raman spectroscopy measurements have been obtained to complete the structural investigation. UV – Visible spectroscopy analysis showed a wide absorbance spectral range of 250 – 2500 nm. Consequently, the CdO nanoparticle displayed photoluminescence emission peak at 508 nm.

A new Pt-Al2O3 double cermet selective solar absorber configuration was prepared using magnetron sputtering system at room temperature. The Scanning Electron Microscopy (SEM) investigations showed that the surface of the Pt-Al2O3 double cermet coating was characterized by a granular structure, while AFM and cross-section SEM analysis revealed a columnar structure with an average height of 45.4 ± 0.1 nm and a surface roughness of 21.1 nm. EDS analysis confirmed the chemical purity of the without any detectable impurities. The coatings showed a combination of a high selective solar absorptance of 0.97 and a thermal emittance of 0.18 at 400 °C, which is better than almost all Al2O3, based selective solar absorbers reported so far. An optical analysis revealed that these favorable properties arise from a combination of interference, and light trapping/absorption effects that occur in the multilayered columnar solar absorber coating. The Pt-Al2O3 cermet showed an excellent photo-thermal conversion efficiency of 88%.

The present work reports on the bio-synthesis and characterization of cadmium oxide nanoparticles (CdO) which were prepared via green synthesis method validating for the first time that oranges peel skin (Citrus x Sinensis) extract is an effective bio-oxidizing/bio-reducing /chelating agent. The prepared nanoparticles were characterized by various techniques such as X-rays diffraction, attenuated total reflection-Fourier transform infrared, Photoluminescence as well as diffuse reflectance. Synthesized samples annealed at various temperature of 200 °C, 300 °C, 400 °C reveal Bragg peaks which were matched to fcc structure of Monteponite CdO while ATR analysis show absorption bands at 548 and 617 cm−1 characteristic of CdO. Photoluminescence spectroscopy analysis shows emission peaks centered at 520 nm meanwhile diffuse reflectance measurement recorded reflectance of 60%, 15%, 8% for samples annealed at 400 °C, 300 °C, 200 °C with respective bandgap of 2.19 eV, 2.42 eV, 2.45 eV.

A novel bio- synthesized Ag nanoparticles (AgNPs) using extracts from khat (Catha edulis) plant which is efficient towards mercury ion detection is reported. Ag NPs were characterized by HRTEM, EDS, FTIR/ATR, XRD, UV–Vis absorbance to investigate the size, morphology, chemical bonding, and optical properties, respectively. HRTEM analysis reveals spherical nanoparticles with an average particle size of 14.8 nm. EDS analysis reveals the presence of Ag on the samples and also week signals of Si, Cl, K, Ca, Fe elements originating from the khat plant. According to the FTIR/ATR analysis, we deduce that the phytochemicals in the khat plant are actively involved in the interaction and reduction of the Ag+ ions to Ag. The Brag peaks identified on the XRD spectra are perfectly matched to Face-centered cubic Ag. The Ag NPs recorded a surface Plasmon resonance (SPR) at 450.279 nm which is responsible for the blue colour shift of mercury ion (Hg2+) detection. As a direct application, the sensitivity of Ag NPs was tested towards mercury ions.

Waste management stays a challenge in developing countries. This research reports on the valorisation of agro-waste for the synthesis of nickel oxide nanoparticles (NiO NPs), useful as antibacterial agents to assure the sustainable use of renewable waste resources for human health protection. Agro-waste extracts from Persea americana seed, Zea mays silk and Eucalyptus globulus leaves were used as chelating agents in combination with nickel nitrate to synthesis NiO NPs. Optical, physical and chemical characteristics of synthesised NiO NPs were analysed by Ultraviolet spectroscopy studies (UV–VIS analysis), X-ray powder diffraction (XRD) and Scanning Electron Microscopy (SEM); Fourier Transform Infrared analysis (FTIR) and Energy Dispersive X-Ray Spectroscopy (EDS), respectively. Antibacterial activity of each synthesised NiO-NPs was determined by cell culture in nutrient agar using well diffusion method. The UV–VIS results showed the formation of NiO NPs at wavelength range 300 – 400 nm. The XRD patterns demonstrated the crystalline form of the NiO NPs with a lattice face-centered cubic with average size of 14, 18 and 19 nm for NiO NPs from Persea americana seed, Zea mays silk and Eucalyptus globulus leaves, respectively. SEM images revealed the spherical, pleomorphism and nanosheet surface shape of the synthesised NiO NPs. Chemical elements K, P, Mg, Na, C and O were detected by EDS analysis as forming part of the elemental composition of the NiO NPs synthesised. Chemical bending between O–H, C–H, C–C and C-N was observed using FTIR. Furthermore, antibacterial studies showed the efficacy of all the NiO NPs synthesised against pathogen microbial growth with the largest inhibition zone (IZ) of 26 mm for the NiO NPs from Eucalyptus globulus leaves being observed. Therefore, Eucalyptus globulus leaves are recommended to synthesise NiO NPs for antibacterial applications.

Green chemistry with its objective of overcoming chemical hazards is an attractive method of synthesising nano-metallic oxides. This study reports for the first time, the green synthesis and characterization of CuO nanoparticles using Mimosa hamata flower extracts as reducing agents. The X-ray diffraction (XRD), Attenuated total reflection-Fourier transform infrared (ATR/FTIR), and Photoluminescence (PL) spectroscopy analyses were subsequently performed post-annealing at 500 °C in air, confirming the formation of Tenorite- based centered monoclinic CuO. The average particle size obtained from the XRD for both annealed and as-preapred samples varied with the concentrations. The energy band gap calculated from the diffuse reflectance was 1.5 eV, 1.3 eV, and 1.2 eV for the different cupric acetate concentrations used, i.e. 0.5, 1.0 and 1.5 g per 10 mL, respectively. The photoluminescence properties obtained at ambient temperature gave emission peaks at 417 and 437 nm which were ascribed to the near-band-edge emission peak of CuO. Furthermore, Anti-bacterial studies were performed on both the as-prepared and annealed CuO for direct application purposes. The as-prepared CuO (liquid form) was demonstrated to have better antimicrobial activity than the CuO powder formed after annealing at 500 °C.

Black Moly (MoO3) coatings obtained by a facile sustainable wet chemical etching method has been investigated to understand the effect of etchant time on the prepared coatings. The effect of the time of etching on the structural, morphological and optical properties of black moly coatings have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and UV–Vis spectroscopy. The XRD spectrum of the prepared coatings showed only peaks from the Molybdenum substrate indicating amorphous coatings. But when annealed at 500˚C, it showed crystallisation to MoO2. In this work, we developed a nanostructured coating, black moly, with a high solar absorptance of over 81%. These results suggest that black moly coatings made from refractory metal oxides can be used for solar thermal absorbers.

In the present work, a novel bio-synthesis of highly crystalline cubic MgO nanoparticles from aqueous extracts obtained from date pits is reported. The synthesised cubic MgO nanoparticles were annealed at 500 and 700 °C for 2 h in air. Characterization of the samples was carried out using various characterization techniques. To show the photocatalytic effectiveness of date pits mediated MgO nanoparticles, degradation ability with Methylene blue (MB) under visible irradiation was evaluated. HRTEM analysis of the samples reveals a spherical-like structure of the nanoparticles while selected area electron diffraction and XRD patterns showed that the annealed nanoparticles are crystalline. The photocatalysis efficiency showed 64 and 52% degradation ability for MB of MgO nanoparticles annealed at 500 and 700 °C, respectively.

In this study, zinc oxide nanoparticles (ZnO NPs) in powder and in thin film were successfully synthesized first time using an eco-friendly, simple and cost effective green synthesis method mediated by corn husk (Zea mays) extract as an effective chelating agent, and zinc nitrate hexahydrate as precursor. Diverse characterizations techniques such as High Resolution - Scanning Electron Microscopy (HR-SEM), Energy Dispersive X- rays Spectroscopy (EDS), X-Rays Diffraction (XRD), and UV - Vis - NIR spectroscopy as well as Photoluminescence (PL) were investigated to confirm ZnO NPs nature. For the ZnO NPs powder, highly crystalline ZnO nanoparticles (ZnO NPs) annealed at 500°C which are 48.635 nm in particles size were characterised by HR-SEM and XRD analysis. The structure morphology and the constituents of the resultant ZnO powder were investigated respectively by HR-SEM and EDS. UV - Visible spectroscopy analysis was investigated on the optical band gap of ZnO NPs, which was calculated to be 3.31 eV. This result indicates that ZnO NPs can be used in metal oxide semiconductor-based devices. For the ZnO NPs thin film, XRD patterns of hexagonal wurtzite structure with c/a ratio about of 1.60 and μ - parameter of 0.38 were obtained. PL measurements showed a broad emission band in the 380 - 800 nm range, centred at 481 nm. ZnO NPs thin film yielded relatively more intense photoluminescence spectra than the ZnO NPs powder. The intrinsic point defects and defect level transitions responsible for the broad emission are discussed.

A novel technique providing a cost effective sustainable wet chemical etching method of synthesizing black Moly thin films rapidly has been presented. A top- down method for fabricating MoO3 has been investigated to understand the effect of chemical etchant concentration on the structural, morphological and optical properties of the thin films on Mo substrates. The XRD patterns demonstrated the formation of Tugarinovite MoO2 films on Mo substrate after annealing at 500°C in a vacuum. In this work, we developed nanostructured MoO3 on Mo substrate solar absorber, with a high solar absorptance of over 89%. These results suggest that solar absorbers made from refractory metal oxide nanostructures can be used for solar thermal applications.

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.

This contribution reports on the physical properties of the natural Namibian red Ochre used by the Himba Community in a form of a formulation, so called Otjize as a skin protective and beauty cream. The morphological and crystallographic studies of this red ochre validated its nano-scaled dominating phase of rhombohedral α-Fe

Background: Of recent, immense attention has been given to chitosan in the biomedical field due to its valuable biochemical and physiological properties such as biodegradability, biocompatibility, non-immunogenicity, reactivity, solubility and non-toxicity. For instance, chitosan has exhibited distinguished bioactivity not limited to only antimicrobial activity but also promotion of wound healing and immune system augmentation in model animals. Therefore, chitosan has attracted application as a nano drug targeted delivery system. Traditionally, the chief source of chitosan is chitin from crab and shrimp shells obtained as waste products in the seafood industry. Chitin is also an important component of fish scales, insects and fungal cell walls, therefore, Uganda’s edible mushrooms, Nile perch scales and banana weevils can be used as alternative sources of chitin and obviously chitosan. Thus, the aim of this study was to isolate and characterize chitosan from locally available material for potential use in the biomedical field. Methods: Chitin was extracted from banana weevils, Nile perch scales and mushrooms powder by demineralization with 1.0M HCl solution, then deproteinization with 1.0M NaOH. Chitosan was prepared by treating chitin with 50% NaOH at 100°C for 8 hrs. Chitosan ash and moisture contents were determined gravimetrically while solubility was computed as percentage dry weight of suspended chitosan. FTIR was used to determine the DD while XRD was used to estimate the crystallinity of chitosan. Results: Ash and moisture contents ranged from 3.5 to 15% and 3.5 to 6.4% respectively while solubility level varied from 57 to 68%. FTIR spectra reveal high degree of similarity between locally isolated chitosan and commercial chitosan with DD ranging from 77.8 to 79.1%. X-Ray Diffraction (XRD) patterns exhibited peaks at 2θ values of 19.5° for both chitosan extracted from Mushrooms and banana weevils while chitosan from Nile perch scales registered 3 peaks at 2θ angles of 12.3°, 20.1° and 21.3° comparable to the established commercial chitosan (Sigma Aldrich) XRD pattern. Conclusion: Ash content, moisture content, DD, FTIR spectra and XRD pattern revealed that chitosan isolated from locally available materials has physicochemical properties comparable to conventional chitosan and therefore it can be used in the biomedical field.

A non-energy intense route was used for the synthesis of highly crystalline WO3 nanocubes. The morphological studies confirmed the cuboidal shape of the nanocrystals. Raman spectrum result for the synthesized sample revealed that the vibrational modes correspond to those ones assigned to single phase stoichiometric WO3. The band gap Eg was derived based on UV-Vis diffuse reflectance result and found to be 2.58 eV, whereas the photoluminescence (PL) result confirmed the blue emission for the synthesized sample. The structural and electronic properties of the orthorhombic WO3 were studied within the spin-polarized density functional theory (SDFT) using various functionals. Results indicated that the orthorhombic WO3 is non-magnetic and has a direct band gap in the range of 2.15–3.75 eV which depends on the exchange-correlation functional used in the theory. The electrochemical studies showed that the nanocubes exhibited a peculiar electrochemical behaviour. In fact, the charge transfer resistances relatively enhanced which may results in decreasing the capacitance of the highly crystalline WO3 nanocubes.

A new ZrOx/Zr/ZrOx/AlxOy multilayered selective solar absorber coating was fabricated using electron-beam vacuum evaporation onto stainless steel (SS), microscope glass slides and silicon (Si) substrates. The structural investigations of the multilayered coatings showed crystalline phases of ZrOx after annealing the coatings at 400 °C for 2 h whereas AlxOy was amorphous, which was also confirmed by Raman spectroscopy. AFM showed uniformly distributed small particles with an average surface roughness value of about 7.29 nm. The optical analysis of the coating exhibits a solar absorbance of 0.93 and low thermal emittance of 0.11 at 100 °C, which is due to mainly interference mechanism and intrinsic absorption as indicated by ellipsometer. These results indicate that a ZrOx/Zr/ZrOx/AlxOy multilayered coating deposited by e-beam evaporation is a good material for selective solar absorbers applications.

Recently, scientists have demonstrated that material surfaces in nature that possess special wettability properties are composed of micro- and nanostructures. In this study, we focused on the importance of surface structures in determining the wettability of wings of the flying insect species: Idea malabarica, Lucilia sericata and Chrysomya marginalis. Scanning Electron Microscopy (SEM) analysis indicates the different nano-/micro- structures identified on the wings. Surface roughness which plays a role in influencing the wettability was theoretically estimated from the SEM images. While the spherical liquid water droplets used for testing wettability were observed to float on the surface of the Idea malabarica and Lucilia sericata wings, the surface of the Chrysomya marginalis wing was made completely wet. The super-hydrophobicity of the Idea malabarica wing as compared to the near-hydrophobicity/mild hydrophilicity of the Lucilia sericata wing and the distinct hydrophilicity of the Chrysomya marginilis wing could be attributed to its complicated composition of nano-/microstructures and higher surface roughness value.

This contribution reports, to the best of our knowledge, for the first time on the neutron tunneling phenomenon in nickel isotopes based nanostructured. More accurately, 58Ni-62Ni-58Ni thin films Fabry-Perot resonator configuration exhibited several tunneling resonances. In total, there were 7 tunneling resonances. These tunneling resonances manifest themselves via sharp dips in the total reflection plateau due to quasi-bound states in the nanostructured isotopic based nickel thin film Fabry-Perot resonator.

The adult Papilio demoleus Linnaeus comes in different sizes (80-100 mm) and colours. On the basis of structural colour observation, an experimental and theoretical study on the different colours on Papilio demoleus Linnaeus wings was conducted. The wing scales were investigated from a photonic crystal perspective using scanning electron and optical microscopies and reflectance measurements. In the SEM measurements, the parts studied show nanostructured ridges separated by crossribs (grooves). The scales show several tilted cuticle layers lapped on the ridges, which constitute a grating. The widths of the ridges and crossribs (grooves) in the grating are different. Arrangements and shapes of scales are clearly seen under the optical microscopy. It was deduced that the yellow colour with the highest reflectance of 485 nm and 580 nm could be due to multiple interferences from a highly tilted cuticle arrangement. The layer arrangement in the brown and ash scales is not enough to reflect observable interference light. The study shows an application in fine light elements in the photo-electro devices.

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.

Supplemental material, sj-pdf-1-jct-10.1177_2380084420981016 for Tooth Loss and Nutritional Status in Older Adults: A Systematic Review and Meta-analysis by R. Zelig, S. Goldstein, R. Touger-Decker, E. Firestone, A. Golden, Z. Johnson, A. Kaseta, J. Sackey, J. Tomesko and J.S. Parrott in JDR Clinical & Translational Research

The study reports computational and experimental synthesis of Mn3O4 nanoparticles using extracts of Phoenix dactylifera otherwise known as date pits for electrochemical applications. The interaction of active compounds which are Gallic acid, L-Glutamic acid, and Sinapic acid contained in date pits serving as reducing agents with the Mn3O4 nanoparticle is investigated using molecular dynamics (MD). The MD analysis enabled to guess the behaviour of the active compounds with the Mn3O4 nanoparticles. Analysis of the density maps and Radial Distribution Function (RDF) showed that, L-Glutamic acid has the most hydrophilicity and the less affinity to interact with the Mn3O4 nanoparticle compare to Gallic and Sinapic acids. By experimental analysis via UV-Vis absorbance, the presence of the active compounds is confirmed at absorbance peaks of 280 and 330 nm. Subsequently, the aqueous extracts obtained from date pits are used to bio-synthesized Mn3O4 nanoparticles. Un-annealed Mn3O4 nanoparticles are thermally oxidized in air for 2 h at 500 °C and 700 °C and subsequently characterized using Diffuse reflectance, XRD, FTIR, HRTEM, HRSEM, and EDS. As direct application, electrochemical properties of Mn3O4 nanoparticles are evaluated using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). XRD analysis revealed plenty of diffraction peaks which are harmonized to Hausmannite Mn3O4 phase. Meanwhile the crystallinity of samples with increasing annealing temperature was evaluated from SAED images characterized by the presence of scattered bright diffractions spots. The electrochemical analysis exhibited an excellent voltammetry response and good electrochemical performance making Hausmannite Mn3O4 nanoplatelets a promising material for electrochemical applications.

The nanostructures on the wings of Idea malabarica (Moore, 1877) were analysed using scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy, Fourier transform-infrared spectroscopy, and reflectance measurements. The chemical and morphological analyses revealed the chitin-based intricate nanostructures. The influence of the nanostructures on the wetting characteristics of the wing was investigated using optical imaging. Applying the Maxwell-Garnet approximation to the porosities within the nanostructures, the refractive indices, which relate the reflectance response, were estimated. It was concluded that the colour seen on the wings of the Idea malabarica originate from the nanostructural configurations of the chitin-based structures and the embedded pigment.

A selective single phase black α-Cr2O3 nanoparticles was bio-synthesised via simple straight-forward green synthesis approach. The process involves extraction of phytochemicals contained in peels of sweet potatoes. Extraction was done in distilled water under constant magnetic stirring at a temperature of 70–80 °C resulting in a dusty yellow colour aqueous extracts. Afterwards, chromic nitrate salt was added to extracts resulting in reduction of metal salt to metal nanoparticles. Obtained precipitates were dried and annealed in the air for 2 h ready to be applied without further post synthesis modifications. SEM and EDS analysis of annealed precipitates reveal distinct shapes and high purity of nanoparticles. The effects of the annealing temperature are evident in the nanoparticle sizes. SAED and XRD patterns expose bright diffraction peaks which are harmonized to the rhombohedral structure of pure Eskolaiteα-Cr2O3. By quantitative analysis of XRD data, it was noted that lattice parameters and crystal sizes slightly decrease w.r.t increase annealing temperature. Raman spectra recorded peaks ascribe to vibrations in A1g and Eg mode whereas FTIR analysis show absorption bands at 641 and 632 cm−1 which evidence the presence of α-Cr2O3 nanoparticles. UV–Vis absorbance peak generated Cr2O3 nanoparticles are observed at 402 nm yielding a band gap of 3.08eV. Magnetism results of α-Cr2O3 nanoparticles shows linear increase upon field increasing, which can be elucidated by the existing of uncompensated spins at the surface of the nanoparticles that may lead to nonmagnetic or antiferromagnetic state. Zero field cooling (ZFC) results of α-Cr2O3 nanoparticles were analysed based on Curie-Wien relation which yield values of magnetic moment (μeff) of the synthesised Cr2O3 nanoparticles close to the value that was assigned for Cr2+.The density functional theory (DFT) with the PW91, PBE, PBESOL and a Hubbard U Coulomb interactionwas utilized to study the optimum structure, electronic and magnetic properties of antiferromagnetically ordered Cr2O3. The computed results are consistent with the experimental measurements.

This paper presents the effects of low-dose γ-irradiation on the structural, morphological, and optical properties of Fluorine-doped tin oxide (FTO) thin films for application as a passive thermal control coating in future miniaturized lightweight spacecraft. Commercial-grade FTO films on glass substrate (Pilkington Ltd, UK) with a bulk density of 2.5 g/cm3, sheet resistance of 12 Ω.sq-1, coating thickness of 450 nm, optical band-gap of 3.80 eV, a carrier concentration of 1.50×1020 cm−3 and a mobility of 15 cm2/Vs were irradiated at room temperature and atmospheric pressure using a 60Co gamma source (with gamma energies of 1.17 MeV and 1.33 MeV) at iThemba Laboratory for Accelerator Based Sciences, Cape Town, South Africa. Each sample was exposed to γ-rays for a different span of time to achieve a series of different integrated absorbed doses of 20, 30, and 50 Gy, at a dose rate of 0.207 Gy/min. Evolution in structural properties of the films was characterized using a Bruker AXS D8 Advance XRD with Cu-Kα (λ = 1.54056 A) scanned in the 2θ degree range of 20 – 80 degrees. Surface properties were analyzed using a VEECO Dimension 1100 AFM machine. Meanwhile, variations in optical transmittance of the films was investigated using a Cary 5000 UV-vis-NIR spectrophotometer of Varian, Inc. model internal DRA- 2500 in the wavelength range of 200 – 2500 nm. XRD results indicate an enhancement of crystallization after irradiation, slight peak shifts, and variations in crystallite sizes with increasing dose. Surface roughness decreased with increasing dose and the grain structures also seen to vary with dose. No significant variations in optical transmittance of the FTO films.

Green chemistry methods for synthesising metal oxides nanoparticles (NPs) have been extensively used due to their tremendous and remarkable advantages such as easy preparation, reliable results, non toxicity, low cost and eco-friendly. Based on these advantages we have applied a green chemistry method for synthesising Nickel Ferrite (NiFe2O4) NPs mediated plant extract from Persa Americano seeds. XRD pattern confirmed the spinel phase structure of the synthesised NiFe2O4 NPs. Fourier Transform Infrared (FTIR) spectroscopy showed the chemical bonds of the sample are consistent with the bonds assigned to NiFe2O4 NPs. Morphological studies revealed the cubic shapes for some of the particles with average sizes range from 15nm to 20nm and irregular shapes for the others. The optical properties were studied using UV–Vis spectrophotometer and the obtained results indicated that NiFe2O4 NPs exhibit a strong absorption behaviour in the UV range with a maximum peak at 250nm. The optical band gap calculated based on UV–Vis result was 4.25 eV. Photoluminescence (PL) spectrum of NiFe2O4 NPs revealed two emission peaks, one in the UV region centred at 379nm and another a broad peak in nearly visible region (Blue emission) centred at 450nm. Magnetic studies showed a decrease in saturation magnetization Ms of NiFe2O4 NPs compared to their bulk system which is attributed to surface spin disorder. Finally, NiFe2O4 NPs exhibited excellent electrochemical properties which can be ascribed to: this compound possess two electrochemical active components and / or the nanocube structure of the particles which can further improve the electrochemistry through the feasible oxidation states and the synergetic effect.

Copper oxide nanoparticles were successfully synthesised via cost effective approach using aqueous extracts obtained from red flowers of Euphorbia pulcherrima. Green precipitates were obtained post-drying which were thermally oxidised to pure single phase monoclinic CuO at 500 °C as per the XRD analysis. Further characterization of un-annealed and annealed samples was carried out using Scanning Electron Microscope (SEM), Optical Microscope (OPM), High Resolution Transmission Electron Microscope (HRTEM), Energy-Dispersive X-ray spectroscopy (EDS), Fourier Transform Infrared spectroscopy (FTIR/ATR), Thermogravimetric analysis (TGA). Zeta potential, X-ray Photoelectron Spectroscopy (XPS), Diffuse Reflectance (DR), UV–Vis and Photoluminescence measurements (PL). Electrochemical properties were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). SEM and OPM analysis on un-annealed and annealed samples reveal elongate and dense cubic agglomerate nanoparticles respectively. EDS spectra confirmed high purity phase composition of CuO. HRTEM analysis of annealed samples revealed a densed cubic nanoparticles, while selected electron area diffraction (SAED) and XRD patterns shows well-crystalline nanoparticles. FTIR/ATR spectra display peaks at 480 and 525 cm−1, which are characteristic peaks of CuO. Zeta potential measurement of annealed samples recorded a value of −6.58 mV. TGA analysis indicated the thermal stability of CuO while XPS analysis confirmed synthesis of pure single phase CuO. Value of energy band gap obtained from diffuse reflectance spectrum was 1.3 eV. From electrochemical study, maximum areal capacitance achieved was 39.45 mF/cm2 at a scan rate of 20 mV/s. This shows that Euphorbia pulcherrima mediated copper oxide nanoparticles is promising material for electrochemical energy storage application.

In this study we mainly report on the magnetic and thermoelectric power properties of the Ce1-xLaxCu4In compounds. XRD results confirm the orthorhombic-CeCu4: 38In1: 62 type structure for all compositions, as well as Vegard’s rule. Resistivity ρ(T) results show an evolution from coherent Kondo scattering to incoherent single-ion Kondo scattering, with increased La content x. The magnetic susceptibility, χ(T) data indicate paramagnetic behaviour and follow the Curie–Weiss law with effective magnetic moment μeff values across the series close to the value of 2.54μB expected for the free Ce 3 + -ion. No evidence of metamagnetic transition was observed from the magnetization results, M(μ0H). For selected representatives of the studied series, thermoelectric power S(T) exhibits a positive maximum, which reaches up to 64.5 µV.K − 1 for the parent CeCu4In. This maximum of S(T) decreases from 64.5 µV.K − 1 to 44.1 µV.K − 1 upon 40% La concentration. Similarly, the thermoelectric power factor PF(T) reached a maximum of 32.6 µW.cm.K − 1 for the parent CeCu4In and decreases with increase in La content x.

A characteristic feature of the giant owl butterfly, i.e. Caligo memnon , is its big wing eyespot. This feature could serve as deceiving functionality for the butterfly against predators. As evidenced by scanning electron microscope (SEM) image on black part of eyespot, the scales on wing eyespot contain nanostructured ridges and cross-ribs. Applying direct measurement, statistical method, and Fourier analysis, the authors evidence that these nanostructures display order–disorder in their shape and position. The autocorrelation of SEM image provides average values of characteristic periods of the order–disorder nanostructures together with an estimation of corresponding correlation lengths. Linecuts obtained from the Fourier transform of SEM image were also analysed with the Hosemann function to extract similar information. These analyses indicate that the nanostructured order–disorder may contribute to blackness on wing eyespot. The authors thus conclude that the blackness on wing eyespot of C. memnon could be attributed to contributions from both the nanostructured order–disorder and melanin pigment.

The ‘plain black’ forewings and black with ‘red spot’ hindwings of the Papilio kotzebuea (Eschscholtz, 1821) were characterized by Scanning Electron Microscopy (SEM), Energy-Dispersive x-ray Spectroscopy (EDS), Atomic Force Microscopy (AFM), Fourier transform Infrared spectroscopy (FT-IR), UV-Vis spectrophometer and NIRQuest spectrometer. SEM images showed that the two sections of wings have different structures. The black with ‘red spot’ hindwings have ‘hair-like’ structures attached to the ridges and connected to the lamellae. On the contrary, the ‘plain black’ forewings have holes that separate the ridges. AFM analysis unveiled that the ‘plain black’ forewings have higher average surfaces roughness values as compared with the black with ‘red spot’ hindwing. EDS and FT-IR results confirmed the presence of naturally hydrophobic materials on the wings. The ‘plain black’ forewing exhibited strong absorptance (97%) throughout the solar spectrum range, which is attributed to the high melanin concentration as well as to the presence of holes in the scales. Biomimicking this wing could serves as equivalent solar absorber material.

This paper investigates the self-assembled chitin based nanostructures of the Caligo Memnon Nymphalidae Felder (1866) butterfly's scales that are responsible for the colour formation on the butterfly's “artificial eyespot”. The Fourier transform analysis of the digital scanning electron microscope images and the calculation of the corresponding half-width Airy disc allowed an effective estimation of the temporal resolution of this “artificial eyespot” as well as its optical sensitivity and optical absorption/light trapping. It was observed that Land equation remains an excellent tool for computing optical sensitivity of nanostructure materials.

This paper examines the electromagnetic energies developed in the scales of the Lepidoptera Danaus plexippus. The Green tensor method was used to calculate and simulate the energies at specific wavelengths. Scattering of electromagnetic waves within the scales was simulated at different wavelengths (λ) with the corresponding maximum energy occurred at λ = 0.45 μm. The study shows that the design of wing’s cross-ribs maximizes the eigenmode of electromagnetic energy. This shows promising applications in bio-sensors of Solar light and likewise in waveguide for photonic transmission.

The study of the substitution of Ca2+ ions by Cd2+ ions in precipitated calcium carbonate is reported. The synthesizing route consists in precipitating CdxCa1−xCO3 particles by rapidly mixing CdCl2 and CaCl2 precursor solutions with Na2CO3 solution. We show experimentally that Cd2+ ions are completely miscible in CdxCa1−xCO3 for x = 0 to x = 1. One interesting point was to investigate whether the vaterite polymorph could be obtained during the precipitation of the initial precursors as it is the case for x = 0. We evidence that vaterite can be obtained only when x is less than 10%. Above this threshold, the calcite structure is the only polymorph observed. Yet, SEM experiments evidence that although the calcite structure is formed at x > 10%, a spheroidal morphology is nevertheless preserved in opposition to the classical rhombohedral one usually observed for calcite. We show by quantitative X-ray analysis that the size of the coherently scattering domains strongly decreases while the strain increases when x increases yielding CdCO3 scattering over a coherent size of about 100 nm.

The research on nano-photonics has been on the increase recently. Among the materials that exhibit stunning optical properties are the nano-photonic materials found in nature such as those on butterfly wings. The wing scales of papilio crino was analysed using the Scanning Electron Microscopy (SEM), UV-Vis-NIR spectrometer, and Optical Microscopy (OPM). Under the OPM, the wing scales was imaged both in normal and polarized (45°) light. The SEM images reveal concave surfaces separated by repeating pattern of ridges and cross ribs. The variation in colour across the concave surface modulation was evident from the optical microscopy images. Through the numerical simulation and CIELab colour space, it was shown that the green colour seen on the wings is a combination of yellow and blue light reflected from different microscopic regions on the wing concave surface. This shows application in the bio-mimicks of retroflection sensors for the detection and classification of optical systems.

In a two-year study, aqueous seed extracts of the neem tree Azadirachta indica A. Juss (Meliaceae) and Bacillus thurigiensis (Bt) were evaluated in the field for the management of pests of okra, Abelmoschus esculentus (L.) Moench. The aqueous neem seed extracts were applied at the rate of 30, 50, 75 and 100 g/l and B.thurigiensis was applied at the rate 1.0 g/l of water. Actellic 25 EC, a synthetic insecticide, was applied at the rate of 2 ml/l as standard check. Arthropod fauna on okra were sampled using traps, sweep nets, aspirators and handpicking. The nature of damage caused to the stems, leaves, flowers and fruit was assessed by visual observation. The major insect pests of okra collected were Podagrica uniformis Jac, Aphis gossypii Glov, Sylepta derogata (F.), Spodoptera litoralis Boisd, Prodenia litura (F.), Dysdercus superstitiosus (F.), Epilachna similis (F.), Bemisia tabaci (Genn.) and Zonocerus variegatus (F.). These pests were observed attacking mainly the leaves of okra. Some of the minor pests identified were Lagria villosa (F.), L. cuprina Thoms, Mylabris temporalis Wellni, M. trifasciata (Thumb.), Lapidognatha sp and Empoasca devastans (D.). Actellic, neem seed extract and Bt significantly reduced the population and damage caused by the major insect pests of okra recorded at Legon, Ghana compared to the untreated. Actellic and aqueous neem seed extracts were equally effective against the pests of okra and caused a significant reduction in insect damage to the leaves, flowers and fruit of the crop. There were no significant differences among the different dosages of neem seed extract on all the parameters assessed, with the exception of the final fruit yield. Actellic, neem extracts or Bt produced higher yield of marketable fruit of okra than untreated plants. Neem seed extract applied at the rate of 30 g/l of water to okra plants produced lower fruit yield than those treated with 50 g or more. Aqueous neem seed extracts and Bt can be used effectively by farmers as a component of integrated management of pests of okra in Ghana. Key words/phrases: Bacillus thurigiensis (Bt), insect pests, neem seed extract, non-synthetic insecticides, okra SINET: Ethiopian Journal of Science Vol.26(2) 2003: 145-150