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λ-Ti3O5 is an intriguing phase-transition material that has been proposed to be metastable and has emerged at room temperature only in the form of nanocrystals. In this work, λ-Ti3O5 was stabilized to room temperature in the form of microcrystals by aluminum (Al)-ion doping. Al entered the Ti3O5 lattice in the substitutional mode, which reduced the threshold temperature (Tc) of the β-λ phase transition in Ti3O5 and maintained a λ-phase Ti3O5 at room temperature. Al doping caused a significant decrease in resistivity of Ti3O5, which corresponds to a semiconductor-metal transition that is induced by Al-ion doping. We have developed a mechanism to fabricate λ-Ti3O5 by ion doping and have provided a fundamental foundation for a more available application of λ-Ti3O5 in smart optoelectronic devices. [ABSTRACT FROM AUTHOR]

Vanadium pentoxide/reduced graphene oxide (V2O5/rGO) nanocomposite film was fabricated by a facial sol-gel method. X-ray diffraction demonstrated that the interlayer distance of V2O5 increased from 1.05 to 1.36 nm due to the introduction of rGO. Raman spectra confirmed the co-existence of V2O5 and rGO in the V2O5/rGO nanocomposite film. Scanning electron microscopy revealed that V2O5 nanoparticles were well distributed on the surfaces of rGO sheets. And cyclic voltammograms and in-situ optical transmittance measurements confirmed that the V2O5/rGO composite film had better cyclic stability, faster switching speed, larger optical modulatory range and higher coloration efficiency compared with the V2O5 film. Moreover, the electrochemical impedance spectroscopy revealed that the V2O5/rGO composite film evinced the lower resistance due to the good interaction between the rGO sheets and the V2O5 nanoparticles. These improvements can be ascribed to the synergistic effect of rGO sheets and V2O5 nanoparticles. This study would be significant for optimizing the electrochromic performances of other transition metal oxide electrochromic materials by the incorporation of rGO. [ABSTRACT FROM AUTHOR]

We investigated the terahertz (THz) transmission characteristics of semiconductor VO2 film and its THz suppression behavior after the phase transition. The VO2 films were deposited by the sol-gel method, and an in situ growth with surface nanocrystallization occurring in the films with increasing thickness was presented. Morphology-induced percolation leads to high THz transparency in the semiconductor VO2 film, and the more compact nanostructure could account for the enhanced THz switching ratio in the metallic film. These results may offer insights into the artificial design of VO2 films for THz device applications. [ABSTRACT FROM AUTHOR]

Abstract: VO2 films on muscovite substrate were fabricated by inorganic sol-gel method and the following thermal treatment. The films were characterized by X-ray diffraction, scanning electron microscope (SEM), fourier transform infrared spectrophotometer (FTIR) and color difference (ΔE*). The FTIR result shows that the film has an infrared transmittance switching efficiency of 77% in the metal-insulator transition. The color changing properties indicate that the film color reversibly changes from khaki to yellow-green as the temperature changes. The relationship between ΔE* and the temperature presents a hysteresis loop, which is in accordance with the infrared optical switching properties. The maximum of ΔE* during the film metal-insulator transition is 11.31. [Copyright &y& Elsevier]

Differential phase-contrast (DPC) X-ray imaging has been performed in the Talbot–Lau configuration, in which the X-ray source was a combination of an absorption grating and a laboratory X-ray generator. We report here quantitative analysis of partial coherence effects on the X-ray Talbot–Lau interferometer. Based on the visibility of the self-image, the well-known geometry condition is reproduced. It is shown that effects of partial coherence are determined by the opening ratio of the source grating, and that the effects are independent of the Talbot order and the type of the phase grating, a condition quite different from those in a Talbot interferometer. A possible explanation is discussed from the point of view of the effective spatial coherence length. Taking into account the available X-ray flux and experimental fluctuations, we present the optimum opening ratio. Furthermore, we mention that our results can also be successfully used to discuss the properties of a multiline X-ray source. [ABSTRACT FROM AUTHOR]

The influence of polychromaticity of the X-ray source on the performance of an X-ray Talbot interferometer applied for phase-contrast imaging is analyzed through numerical simulations based on the Fresnel diffraction theory. The presented simulation results show that the visibility of the self-image is fairly insensitive to the source polychromaticity and explain why the interferometer could be well combined with polychromatic X-ray sources in recent experiments. Furthermore, the self-image with a high visibility can be obtained under polychromatic illumination even at a high-order fractional Talbot distance. This fact implies that the acquired image quality for phase measurements can be improved, since the primary signal for phase measurement is proportional to the inter-grating distance. Finally, we mention that the results are also valid for Talbot–Lau interferometer and scanning double-grating configuration. [ABSTRACT FROM AUTHOR]

A simple framework that allows a new general diffraction enhanced imaging (DEI) equation to be derived is presented. This latter equation may explain all open problems associated with the equation introduced by Chapman and those not explained by the first DEI equation, such as the noise background due to the small-angle scattering reflected by the analyzer. Combing the DEI equation with computed tomography (CT) theory, we propose a new DEI–CT formula that explains qualitatively the contour contrast caused by extinction of the refraction. Two formulae with a new method to extract the refraction angle are also introduced. Within this new theoretical framework the three components of the gradient of the refractive index can be reconstructed. [ABSTRACT FROM AUTHOR]

The investigation of the internal morphology of insects is usually performed using classical microtomy yielding optical micrographs of stained thin sections. The achievement of high-quality cross sections for microtomy is time-consuming and the risk of damaging sections is unavoidable. Moreover, the approach is impractical, in particular when quick acquisition of 3D structural information is required. Recently, X-ray computed microtomography (micro-CT) with a high spatial resolution was considered as a potential tool for the morphological classification of insects. We used micro-CT to investigate Quedius beesoni Cameron at the cellular length scale. This method provides a new powerful and nondestructive approach to obtain 3D structural information on the biological organization of insects. The preliminary images presented in this contribution clearly reveal the endoskeleton and the muscles of the head and the thorax with a full 3D structure. We also reconstructed the 3D structure of the brain of Quedius beesoni Cameron, and this is the first reconstruction in Staphylinidae, which will be a great advancement for morphological and phylogenic research. We claim that both the spatial resolution and the contrast characteristic of micro-CT imaging may fulfill the requirements necessary for zoological insect morphology and phylogeny, in particular, when a classification of a rare and unique insect specimen is required. [ABSTRACT FROM AUTHOR]

In this article, a pH sensitive semi-interpenetrating network (SIPN) hydrogel based on methacrylic acid, BSA, and PEG was prepared by UV initiated free radical polymerization. The swelling behavior and pH sensitivity of these hydrogels were studied in detail. With the increase in pH of the aqueous solution from 1.7 to 9.23, the swelling ratio of these hydrogels increased accordingly. The effect of BSA and crosslinker (BIS) content on the swelling behavior was more complicated, and the results were shown in the text. [ABSTRACT FROM AUTHOR]

This paper presents the design, simulation, and measurement of an asymmetric triple-band metamaterial composed of single geometry electric field coupled resonators in the terahertz region. Theoretical and experimental results show that the structure has three distinct and strong absorption frequency peaks near 0.38, 0.58, and 0.74 THz, all of which are related to the inductance-capacitance resonance of the metamaterial. Due to the well-separating of different resonances in the particle, this metamaterial shows potentially application promises in the design of multiband terahertz devices. [ABSTRACT FROM AUTHOR]

We demonstrate that Ag–Si photodiodes allow photocurrents to be modulated by changing periods of nanopatterns on Ag film. The maximum and minimum photocurrents occur in certain periods corresponding to the excitation of surface plasmon polariton and Wood’s anomaly, which can be predicted with the help of related theories. Therefore, it is feasible to design nanopatterns to satisfy special requirements. [ABSTRACT FROM AUTHOR]

An imaging system based on a polycapillary half-focusing X-ray lens (PHFXRL) and synchrotron radiation source has been designed. The focal spot size and the gain in power density of the PITIFXRL were 22 μm (FWHM) and 4648, respectively, at 14.0 keV. The spatial resolution of this new imaging system was better than 5 μm when an X-ray charge coupled device with a pixel size of 10.9 x 10.9 μm was used. A fossil of an ancient biological specimen was imaged using this system. [ABSTRACT FROM AUTHOR]

A new diarylbenzophenone, namely selagibenzophenone C (1), along with 1,3-di-p-hydroxyphenyl4-penten-1-one, (2) and unciflavone E (3) were isolated from Selaginella tamariscina. Their structures were elucidated on the basis of spectroscopic and mass spectrometric analyses, including 1D-, 2D-NMR and HRESIMS. Compound 1 represents the first example of naturally occurring diarylbenzophenone. Compound 2 was firstly isolated from the genus of Selaginella. [ABSTRACT FROM AUTHOR]

Integrating nanostructures onto optical fibers presents a promising strategy for developing new-fashioned devices and extending the scope of nanodevices’ applications. Here we report the first fabrication of a composite silicon nanostructure on an optical fiber. Through direct chemical etching using an H2O2/HF solution, multicrystal silicon films with columnar microstructures are etched into a vertically aligned, inverted-cone-like nanorod array embedded in a nanocone array. A faster dissolution rate of the silicon at the void-rich boundary regions between the columns is found to be responsible for the separation of the columns, and thus the formation of the nanostructure array. The morphology of the nanorods primarily depends on the microstructure of the columns in the film. Through controlling the microstructure of the as-grown film and the etching parameters, the structural control of the nanostructure is promising. This fabrication method can be extended to a larger length scale, and it even allows roll-to-roll processing. [ABSTRACT FROM AUTHOR]

We investigate analytically the subwavelength plasmonic lattice solitons excited in an optical plasmonic waveguide consisting of a chain of nanorods embedded in a Kerr nonlinear optical medium with strong near-field interactions. A nonlinear lattice equation with onsite and intersite nonlinear terms describing the plasmon wave propagating along the chain is derived. Stability analysis predicts that modulation instability can occur and that, correspondingly, conditions for localized modes will exist. We analyze the nonlinear excitations for genuine discreteness and nonlinearity enhanced by the fields strongly confined in the nanosized dielectric gaps. Based on a quasidiscreteness approach, we obtain a nonlinear Schròdinger equation and find that the system supports bright and dark soliton solutions in different frequency bands. It is also shown that the existence of different solitons depends strongly on the type of nonlinearity of the embedded medium. [ABSTRACT FROM AUTHOR]