Optical wireless communication using a flexible and waterproof perovskite color converter.

In this Letter, the CH3NH3PbBr3 nanocrystals (NCs) are embedded into the interstices of the fluorine (polyvinyl fluoride/polyvinylidene fluoride, PVF/PVDF) matrix on polyethylene terephthalate (PET) substrate to introduce new advantages, such as being flexible and waterproof, while maintaining the high optical performance of perovskites. The sample's photoluminescence (PL) spectra under 325 nm laser is a green emission peaked at 537 nm with full width at half maximum (FWHM) of about 21.2 nm and a fast PL decay time. As a color converter, it shows high optical absorption and can transform light from solar-blind ultraviolet to a blue region into a green region in air, water, and bending conditions. While excited by a 270 nm ultraviolet light-emitting diode (LED), the system's observed -3 dB bandwidth with the color converter is near 4.4 MHz in air and water conditions with well-eye diagrams at a data rate of 30 Mbps. Finally, we demonstrate an audio transmission application with an ultraviolet light source, a color conversion layer, and a low-cost silicon-based photodetector.

Chemical Solution Route for High-Quality Multiferroic BiFeO3 Thin Films.

Bismuth ferrite (BiFeO3 ) has recently become interesting as a room-temperature multiferroic material, and a variety of prototype devices have been designed based on its thin films. A low-cost and simple processing technique for large-area and high-quality BiFeO3 thin films that is compatible with current semiconductor technologies is therefore urgently needed. Development of BiFeO3 thin films is summarized with a specific focus on the chemical solution route. By a systematic analysis of the recent progress in chemical-route-derived BiFeO3 thin films, the challenges of these films are highlighted. An all-solution chemical-solution deposition (AS-CSD) for BiFeO3 thin films with different orientation epitaxial on various oxide bottom electrodes is introduced and a comprehensive study of the growth, structure, and ferroelectric properties of these films is provided. A facile low-cost route to prepare large-area high-quality epitaxial BFO thin films with a comprehensive understanding of the film thickness, stoichiometry, crystal orientation, ferroelectric properties, and bottom electrode effects on evolutions of microstructures is provided. This work paves the way for the fabrication of devices based on BiFeO3 thin films.

[Pseudo color method for the infrared thermogram display of local breast focus tissue].

An infrared thermogram which reflects the human body surface temperature distribution can be obtained through detecting the infrared thermal radiation from each point on the human body surface. When a malignant tumor occurs in a breast, it will cause an increase in the prominent temperature in the breast surface focus region due to the abnormal blood transmission state of local focus tissue. Breast cancer can be detected through the visual analysis of the focus regions by physicians. In order to help physicians better find these focus regions, the present paper improved the traditional pseudo color display method by introducing visual effect factor and made the focus regions have a better display effect. The efficacy of this method was verified in the breast infrared thermograms of 47 breast cancer patients. The result from visual analysis of the focus region in infrared thermogram by this method can also be compared with the tissue blood transmission state from near infrared spectroscopy (NIRS) and other methods. It will be helpful to obtain more accurate diagnostic information.

Highly Ambient-Stable 1T-MoS2 and 1T-WS2 by Hydrothermal Synthesis under High Magnetic Fields.

The phase-controlled synthesis of metallic and ambient-stable 2D MX2 (M is Mo or W; X is S) with 1T octahedral coordination will endow these materials with superior performance compared with their semiconducting 2H coordination counterparts. We report a clean and facile route to prepare 1T-MoS2 and 1T-WS2 through hydrothermal processing under high magnetic fields. We reveal that the as-synthesized 1T-MoS2 and 1T-WS2 are ambient-stable for more than 1 year. Electrochemical measurements show that 1T-MoS2 performs much better than 2H-MoS2 as the anode for sodium ion batteries. These results can provide a clean and facile method to prepare ambient-stable 1T-phase MX2.

Enhancement of Low-field Magnetoresistance in Self-Assembled Epitaxial La0.67Ca0.33MnO3:NiO and La0.67Ca0.33MnO3:Co3O4 Composite Films via Polymer-Assisted Deposition.

Polymer-assisted deposition method has been used to fabricate self-assembled epitaxial La0.67Ca0.33MnO3:NiO and La0.67Ca0.33MnO3:Co3O4 films on LaAlO3 substrates. Compared to pulsed-laser deposition method, polymer-assisted deposition provides a simpler and lower-cost approach to self-assembled composite films with enhanced low-field magnetoresistance effect. After the addition of NiO or Co3O4, triangular NiO and tetrahedral Co3O4 nanoparticles remain on the surface of La0.67Ca0.33MnO3 films. This results in a dramatic increase in resistivity of the films from 0.0061 Ω•cm to 0.59 Ω•cm and 1.07 Ω•cm, and a decrease in metal-insulator transition temperature from 270 K to 180 K and 172 K by the addition of 10%-NiO and 10%-Co3O4, respectively. Accordingly, the maximum absolute magnetoresistance value is improved from -44.6% to -59.1% and -52.7% by the addition of 10%-NiO and 10%-Co3O4, respectively. The enhanced low-field magnetoresistance property is ascribed to the introduced insulating phase at the grain boundaries. The magnetism is found to be more suppressed for the La0.67Ca0.33MnO3:Co3O4 composite films than the La0.67Ca0.33MnO3:NiO films, which can be attributed to the antiferromagnetic properties of the Co3O4 phase. The solution-processed composite films show enhanced low-field magnetoresistance effect which are crucial in practical applications. We expect our polymer-assisted deposited films paving the pathway in the field of hole-doped perovskites with their intrinsic colossal magnetoresistance.

[Spectral colorimetric correction of full view color images in a real scene measurement system].

In the three dimensional multiple modalities scanning real scene measurement system, a color linear CCD was used to obtain the one dimensional linear color information of the scene. Successive one dimensional color images of different angles were patched to constitute the full view color image. If the color image is displayed directly on the color cathode ray tube (CRT) monitor of a computer, colorimetric distortion will occur. Colorimetric correction is then needed. Through thespectral colorimetric correction, the colorimage displayed on the color CRT monitor is matched with the original scene in the colorimetric sense.

Transparent conducting p-type thin films of c-axis self-oriented Bi2Sr2Co2O(y) with high figure of merit.

Transparent conducting p-type Bi2Sr2Co2O(y) thin films have been first grown on SrTiO3 substrates by a chemical solution deposition, showing c-axis self-orientation. The figure of merit can reach as high as 800 MΩ(-1), which is the highest value for p-type transparent conducting thin films by solution methods.

Epitaxial antiperovskite superconducting CuNNi3 thin films synthesized by chemical solution deposition.

Epitaxial antiperovskite superconducting CuNNi3 thin films have been grown by chemical solution deposition. The film is a type II superconductor and shows a Tc of 3.2 K with a transition of 0.13 K. The Hc2(0) and ξ0 are estimated to be 8.1 kOe and 201 Å, respectively.

Synthesis and characterization of ordered and disordered polycrystalline La2NiMnO6 thin films by sol-gel.

Polycrystalline La(2)NiMnO(6) thin films are prepared on Pt/Ti/SiO(2)/Si substrates by the sol-gel method. Through controlling the processing parameters, the cation ordering can be tuned. The disordered and ordered thin films exhibit distinct differences for crystal structures as well as properties. The crystal structure at room temperature characterized by X-ray diffraction and Raman spectra is suggested to be monoclinic (P2(1)/n) and orthorhombic (Pbnm) for the ordered and disordered thin films, respectively. The ferromagnetic-paramagnetic transition is 263 K and 60 K for the ordered and disordered samples respectively, whereas the saturation magnetic moment at 5 K is 4.9 µ(B) fu(-1) (fu = formula unit) and 0.9 µ(B) fu(-1). The dielectric constant as well as magnetodielectric effect is higher for the ordered La(2)NiMnO(6) thin films. The magnetodielectric effect for the ordered thin film is dominantly contributed to the intrinsic coupling of electric dipole ordering and fluctuations and magnetic ordering and fluctuations, while it is mainly contributed to Maxwell-Wagner (M-W) effects for the disordered thin film. The successful achievements of ordered and disordered polycrystalline La(2)NiMnO(6) thin films will provide an effective route to fabricate double-perovskite polycrystalline thin films by the sol-gel method.

Synthesis and characterization of self-assembled c-axis oriented Bi2Sr3Co2O(y) thin films by the sol-gel method.

Bi(2)Sr(3)Co(2)O(y) thin films are prepared on SrTiO(3) (100), (110) and (111) single crystal substrates using the sol-gel method. All the thin films are c-axis oriented regardless of the orientation of the substrate suggesting self-assembled c-axis orientation, and X-ray photoelectron spectroscopy results give evidence of coexistence of Co(3+) and Co(2+) ions in the derived films. Transmission electronic microscopy observations reveal that all samples are c-axis oriented with no obvious differences for different samples, and the c-axis lattice constant is determined as ~15 Å suggesting the misfit structure. A phenomenological thermodynamic phase diagram for self-assembled c-axis orientation is established for misfit cobaltate-based films using chemical solution deposition. All samples behave like semiconductors due to the coexistence of Co(3+)/Co(2+) ions, and the resistivity at 350 K is ~47, 39 and 17 mΩ cm for the thin films on SrTiO(3) (100), (110) and (111), respectively, whereas the Seebeck coefficient at 300 K is 97, 89 and 77 µV K(-1). The successful attainment of Bi(2)Sr(3)Co(2)O(y) thin films with self-assembled c-axis orientation will provide an effective prototype for investigation of growth mechanisms in complex oxide thin films with a misfit structure.

Asymmetry analysis of breast thermograms with morphological image segmentation.

Breast thermography is considered particularly valuable for early breast tumors detection. The fast growing tumor has a higher metabolic rate and associated increase in local vascularization. It will cause the occurrence of some asymmetric heat patterns. Clinical interpretation of a breast thermogram is primarily based on the asymmetry analysis of these heat patterns visually and subjectively. In this paper, a new approach of asymmetry analysis of breast thermograms was proposed. The heat patterns are first segmented with mathematical morphology. The asymmetry analysis is performed both qualitatively and quantitatively according to the extracted features. The abnormality of a breast thermogram is clearly indicated by the features.