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Abstract: The sensing of gasses/vapors in the ambient air is the focus of attention due to the need to monitor our everyday environment. Photonic crystals are sensing materials of the future because of their strong light-manipulating properties. Natural photonic structures are well-suited materials for testing detection principles because they are significantly cheaper than artificial photonic structures and are available in larger sizes. Additionally, natural photonic structures may provide new ideas for developing novel artificial photonic nanoarchitectures with improved properties. In the present paper, we discuss the effects arising from the sensor temperature and the vapor concentration in air during measurements with a photonic crystal-type optical gas sensor. Our results shed light on the sources of discrepancy between simulated and experimental sensing behaviors of photonic crystal-type structures. Through capillary condensation, the vapors will condensate to a liquid state inside the nanocavities. Due to the temperature and radius of curvature dependence of capillary condensation, the measured signals are affected by the sensor temperature as well as by the presence of a nanocavity size distribution. The sensing materials used are natural photonic nanoarchitectures present in the wing scales of blue butterflies. [Copyright &y& Elsevier]

Linearly polarized light microscopy (PM) revealed that graphene grown by chemical vapor deposition (CVD) on stepped Cu substrate may appear colored. The coloration is associated with the coupling of the light of 450-600 nm into propagating mode in the graphene layer when the electric vector (Evector ) of polarized light is parallel with the step edges and with the scattering when the Evector is normal to the step edges. PM is an inexpensive, fast, and contamination free method to efficiently visualize graphene and to map the step structure of Cu substrates used for large area CVD growth of graphene. [ABSTRACT FROM AUTHOR]

Abstract: The color generating nanoarchitectures in the cover scales of the blue (dorsal)–green (ventral) wing surfaces of the butterfly Albulina metallica were investigated by scanning electron microscopy and cross-sectional transmission electron microscopy. A layered, quasiordered structure was revealed in both the dorsal and ventral scales, with different order parameters, associated with their different colors. A successful attempt was made to reproduce the biological structure in the form of a quasiordered composite (SiO/(In & SiO)) multilayer structure using standard thin film deposition techniques. The position of the reflectance maxima of this artificial structure could be tailored by controlling the size of the In inclusions through oxidation. Our results show that photonic band gap materials of biologic origin may constitute valuable blueprints for artificial structures. [Copyright &y& Elsevier]

Abstract: The photonic crystal type nanostructures in the scales of male individuals of two butterfly species: Cyanophrys remus and Albulina metallica were investigated by electron microscopy and reflectance measurements. While the colors of C. remus arise from structures with rigorous long range (dorsal) or short range (ventral) three dimensional (3D) order, the colors of A. metallica are produced by quasi-ordered, layered structures. Surprisingly, the most efficient photonic band gap reflector is the quasi-ordered structure giving the shiny, yellowish green color of the ventral hind wings of A. metallica. All four investigated structures are based on a moderate refractive index contrast between chitin (n =1.58) and air, the various structures achieve a wide range of biological functions. [Copyright &y& Elsevier]

AimTo quantitatively assess corneal endothelial changes after phacoemulsification with the fluid-based system compared to conventional ultrasound technique.MethodsThis prospective, randomized clinical study included patients with cataract who were randomly assigned either to have phacoemulsification with the fluid-based system (30 eyes of 30 patients—Group 1) or with traditional ultrasound (30 eyes of 30 patients—Group 2). Patients who were available at each follow-up visit (25 eyes in both groups) were enrolled in the statistical analysis. Endothelial function was evaluated by measuring central corneal thickness, central endothelial cell density (ECD), mean cell size, and coefficient of variation in cell size preoperatively, 10 days, 1 and 3 months, and 1 year after surgery. Statistical analyses were performed using two-way repeated measure ANOVA.ResultsAn acute, reversible increase of central corneal thickness (CCT) was found 10 days after surgery, which was similar in both groups (P=0.35). ECD decreased, whereas mean cell size increased significantly immediately after surgery. However, the impairments were finished after 1 month. The alterations were similar in both groups (ECD: P=0.99; mean cell size: P=0.85). The coefficient of variation in cell size remained stable after surgery (P=0.08), and significant difference was not found between groups (P=0.99). The endothelial cell loss (ECL) was 6.5±8.4% in Group 1 and 6.5±11.7% in Group 2 (P=0.69).ConclusionsCorneal endothelial changes were similar using the fluid-based system compared to the traditional ultrasound technique. The fluid-based method proved to be as safe as conventional ultrasound in cataract surgery.Eye (2007) 21, 727–732; doi:10.1038/sj.eye.6702314; published online 3 March 2006 [ABSTRACT FROM AUTHOR]

Abstract: Despite of the very promising foreseen applications, the use of carbon nanotubes in wider range is still limited by the high production costs. In this paper, our latest results concerning two inexpensive methods of carbon nanotube growth with the promise of industrial upscaling are presented. In case of the DC “arc in water” method, the effect of the angle of the two electrodes on the product yield was investigated. The highest nanotube yield and lowest amount of impurities were found at 90° electrode angles. We have studied the applicability of several liquid hydrocarbons and other metallocenes different from the most widely used benzene/ferrocene solution in case of the injection CVD or “spay pyrolysis” method. Toluene, xylene, cyclohexane, cyclohexanone, n-hexane, n-heptane, n-octane and n-pentane were used as carbon source and cobaltocene and nickelocene as catalyst source. All these compounds were found to be suitable for nanotube production. The highest yield and the best quality were obtained when a mixture of ferrocene–nickelocene was used as catalyst and xylene as carbon source. [Copyright &y& Elsevier]

Abstract: Photonic crystal type structures of biological origin were investigated by scanning electron microscopy (SEM) and UV–VIS reflectance measurements. It was demonstrated that despite the moderate refractive index contrast between chitin and air, biological evolution developed in the wing scale nanostructures of butterflies representing various families, numerous structures with different hues of blue and very different degrees of directionality. Furthermore, for illustrating the variety of purposes for which nature may use photonic structures, the UV protection mechanism of the high altitude flower Edelweiss has been investigated. We present fully supportive data that the protection mechanism is based on coupling by nanostructured, highly selective couplers the harmful UV radiation in propagating modes along fibers containing UV absorbing pigment. [Copyright &y& Elsevier]

Abstract: A systematic study on the controlled growth of large areas of aligned multi-wall carbon nanotube arrays, from ferrocene–benzene precursor, and of nanotube junctions from ferrocene–thiophene precursor, without hydrogen addition, using an injection CVD method easy to scale up for industrial production is reported. A detailed study is presented of how the synthesis parameters such as growth temperature, active solution flow rate, catalyst concentration or sulfur addition can control the properties and morphology of the grown nanotube mat. Nanotube junctions with considerable yield can be grown with our method by adding sulfur to the synthesis process. The sulfur addition also results in growth of carbon nanocones (CNC) in the lower temperature regime of the furnace. Observation of single-wall carbon nanotubes in our STM investigations provides further indication that under properly chosen conditions SWCNTs can be grown with similar continuous processes. [Copyright &y& Elsevier]

The penelfin Penaincisalia alina sp. nov. is described from Department Apurímac, Peru on the basis of wing and genitalia characters. Spectral analysis of structural colours carried out on congeneric species is presented. A hitherto unnamed Penaincisalia species from the vicinity of the type locality is also documented. [ABSTRACT FROM AUTHOR]

We constructed a new type of light-weight, nanocarbon based thin film material having good mechanical properties, thermal stability, and electromagnetic shielding efficiency. Our method, 3D printing combined with hot pressing, is a cheap and industrially upscalable process. First a sandwich structure was created by layer-to-layer deposition of alternating 100 lm thick nanocarbon containing plastic layers and 100 lm thick pristine plastic layers, repeated as building blocks. The 3D printed samples were hot pressed to obtain thin films of 10-30 lm thickness. We used a commercial nanocarbon 3D printing filament (Black Magic). TEM investigations revealed the nanocarbon filler to be a mixture of graphene sheets, short carbon nanotubes, fishbone nanotubes, graphitic nanoparticles, and carbon black. Small-angle X-ray scattering and X-ray diffraction studies showed some amorphization of the nanocarbon filler as a consequence of the hot pressing. The nanoindentation hardness, nanoscratch hardness, and Young's modulus increase gradually by increasing the number of layers in the films, due to an increase of the amount of nanocarbon filler. Microwave absorption also increases continuously with the number of nanocarbon layers, reaching 40% for 3 nanocarbon layers. We demonstrate that unlike most conventional composites loaded with nanocarbons having pronounced dielectric properties, when the real part of permittivity Re(e) is much higher than its imaginary part Im(e) at high frequencies, a combination of 3D printing and hot pressing allows the fabrication of composites with Re e ≈ Im e in a very broad frequency range (0.2-0.6 THz). Our new 3D printed—hot pressed thin films may compete with the CVD graphene sandwiches in electromagnetic shielding applications because of their easier processability and low cost. [ABSTRACT FROM AUTHOR]

A new type of light-weight material produced by 3D printing consisting of nano-carbon doped polymer layer followed by a dielectric polymer layer is proposed. We performed temperature dependent characterization and measured the electromagnetic (EM) response of the samples in the GHz and THz range. The temperature dependent structural characteristics, crystallization, and melting were observed to be strongly affected by the presence and the number of nano-carbon doped layers in the sandwich structure. The electromagnetic measurements show a great potential of such a type of periodic material for electromagnetic compatibility applications in microwave frequency range. Sandwich structures containing only two nano-carbon layers already become not transparent to the microwaves, giving an electromagnetic interference shielding efficiency at the level of 8-15 dB. A sandwich consisting of one nano-carbon doped and one polymer layer is opaque for THz radiation, because of 80% of absorption. These studies serve as a basis for design and realization of specific optimal geometries of meta-surface type with the 3D printing technique, in order to reach a high level of electromagnetic interference shielding performance for real world EM cloaking and EM ecology applications. [ABSTRACT FROM AUTHOR]

The aim of our study was to investigate the correlation between structural colour and scale morphology in butterflies. Detailed correlations between blue colour and structure were investigated in three lycaenid subfamilies, which represent a monophylum in the butterfly family Lycaenidae (Lepidoptera): the Coppers (Lycaeninae), the Hairstreaks (Theclinae) and the Blues (Polyommatinae). Complex investigations such as spectral measurements and characterization by means of light microscopy, scanning electron microscopy and transmission electron microscopy enabled us to demonstrate that: (i) a wide array of nanostructures generate blue colours; (ii) monophyletic groups use qualitatively similar structures; and (iii) the hue of the blue colour is characteristic for the microstructure and nanostructure of the body of the scales. [ABSTRACT FROM AUTHOR]

Male secondary sexual characters have been discovered on the hindwing verso of genera Aphnaeus Hübner, [1819], Cigaritis Donzel, 1847, Lipaphnaeus Aurivillius, 1916 and Pseudaletis Druce, 1888 representing the Palaeotropical subfamily Aphnaeinae (Lycaenidae: Lepidoptera). Relevant wing parts are illustrated, described, and some observations on the organs are briefly annotated. With an appendix and 14 figures. [ABSTRACT FROM AUTHOR]

Chemical sensing properties of single wire and mat form sensor structures fabricated from the same carbon nanotubes (CNT) materials have been compared. Sensing properties of CNT sensors were evaluated upon electrical response in the presence of five vapours as acetone, acetic acid, ethanol, toluene, and water. Diverse behaviour of single wire CNT sensors was found, while the mat structures showed similar response for all the applied vapours. This indicates that the sensing mechanism of random CNT networks cannot be interpreted as a simple summation of the constituting individual CNT effects, but is associated with another robust phenomenon, localized presumably at CNT-CNT junctions, must be supposed. [ABSTRACT FROM AUTHOR]

Abstract: Bioinspired, regular, rectangular (with periodicities of 600nm and 700nm), and random (with average characteristic distances of 600nm and 750nm) two dimensional (2D) photonic nanoarchitectures of 60nm thickness were produced in graphite by Focused Ion Beam (FIB) nanomachining and subsequent controlled oxidation. The color of the nanoarchitectures was modified by the conformal deposition of 90nm Al2O3. The regular patterns generate iridescent colors, while the random ones exhibit a remarkably constant color with the variation of the illumination and viewing conditions. [Copyright &y& Elsevier]

The structure of novel forms of carbon nanostructures (Haeckelites) is investigated combining modeling with experimental data. New arguments are given for the existence of a theoretically predicted sp2 hybridized carbon form, with structure close to that of graphite, called Haeckelite (Terrones et al., Phys. Rev. Lett. 84 (2000) 1716). The major difference between Haeckelite and graphite is given by the regular occurrence of non-hexagonal carbon rings as building blocks of Haeckelite. It is proposed that the necklace of pearls type nanostructures investigated by SEM, TEM and HRTEM, are built of Haeckelite and a structural model which allows a graphitic interlayer spacing for multilayer Haeckelite necklaces is proposed. [Copyright &y& Elsevier]

A simple, low cost and continuous growth method for the production of well graphitized multi-wall carbon nanotubes is described. The growth takes place in an AC arc in water between two carbon electrodes. At a voltage of 40 V the arc is stable in the range of 85–45 A, lower current values help in increasing the fraction of carbon nanotubes in the product. [Copyright &y& Elsevier]