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Chinese Edison pearls, invented and produced in China by the Zhejiang Grace Pearl Jewelry Co., Ltd, are usually large and round with variable but attractive colors. Edison pearls have entered the jewelry market in 2011. However, the fine microstructural characteristics of these pearls remain largely unknown, particularly the thickness of the nacre and the spatial distributions of organic pigment in the nacre. Herein, using X-ray microradiography analysis, field-emission scanning electron microscopy, and Raman spectroscopy, we comprehensively investigated the internal fine-microstructural characteristics of typical colored Edison pearls. Our results indicated that Edison pearls have a typical core–shell structure, in which the core is the nucellus and the shell is the nacre. Average nacre thicknesses varied from 1.00 to 3.60 mm among specimens. Surprisingly, theoretical calculations showed that nacre accounted for about 50–90% of the whole pearl by volume. In addition, multiple prismatic or irregular structures, almost entirely composed of aragonite, coexisted in the nacre of some Edison pearls; one of these structures was closely adjacent to the nucleus. Interestingly, the average thickness of individual aragonite tablets in the nacre gradually decreased from the inner nacre (near the nucleus) to the outer nacre (near the pearl surface). Finally, the intensity ratios of the two peaks in the Raman spectra (I1124–1134/I1085) were non-uniform across nacre regions, and generally increased with distance from the nucleus. This pattern was directly attributed to variations in pigment content among nacre regions. Our results substantially increase our understanding of nacre biomineralization and the gemological characteristics of colored Edison pearls. More importantly, this study identified certain characteristics that can be used to identify color-treated Edison pearls. [ABSTRACT FROM AUTHOR]

Porous carbon nanofibers (PCNFs), are widely used as free-standing anode materials for lithium-ion batteries (LIBs), due to their high specific surface area and excellent ion diffusion kinetics, but they also present problems of reduced rate performance and cycling performance, due to poor strength caused by porosity. Herein, a novel surface porous carbon nanofiber (SPCNFs) is prepared by coaxial electrospinning, followed by carbonization. All the pores are distributed in the shell of the fibers, with a dense amorphous carbon structure in the core, which would not only provide abundant lithium-ion embedding sites, and accelerate the penetration of electrolyte ions, but also alleviate the reduction of mechanical properties (with a ~ 30% improvement to PCNFs). Consequently, our LIBs assembled with this SPCNFs anode represent remarkable cycling stability (445.33 mAh g−1 at 100 mA g−1 after 100 cycles and 388.92 mAh g−1 at 1 A g−1 after 1000 cycles), and excellent rate capacity (317.55 mAh g−1 at 1 A g−1). [ABSTRACT FROM AUTHOR]

Highly conductive and flexible graphene-based microtubes (μ-GTs) have many potential applications in catalyst supports and wearable electronics. However, there is a lack of effective method to fabricate the high-performance μ-GTs, especially the multi-channel ones. In this work, the electrostatic spray deposition technique was introduced to fabricate the graphene oxide-coated polyester thread from cost-efficient graphene oxide suspensions. After the polyester thread template was removed along with the reduction of graphene oxide by thermal annealing, the multi-channel μ-GT was prepared successfully. Due to the multiple structure of the cross section and the vertically aligned reduced graphene oxide sheets of the tube wall, the multi-channel μ-GT exhibits many excellent properties, such as highly conductive, good flexibility, and functionalization. For example, the electrical conductivity of the multi-channel μ-GT thermally reduced at 1200 °C is about 1.99 × 104 S m−1 at room temperature and can light a LED as a conductive wire. And the electrical conductivity is nearly invariable in either the straight or bent state though a cyclic bending test up to 800 times. In addition, the TiO2/multi-channel μ-GT composite shows strong photocurrent response in which the multi-channel μ-GT provides a super platform due to the high specific surface area. The high-performance μ-GTs obtained by the simple method opens the immense potentials for application in wearable devices. [ABSTRACT FROM AUTHOR]

UV-Vis reflectance spectroscopy combined with field emission scanning electron microscopy (FE-SEM) was used to characterize the nacres of seawater and freshwater cultured pearls and shells. While distinct spectral features were observed for different types of pearls or shells, a characteristic absorption band at about 275 nm was identified in the UV-Vis spectra for the nacres of pearls and shells regardless of their growing environments or physical appearance. The UV absorption peak was no longer observable after the nacres were coated with Pt, indicating that the laminated structure of the nacre's surface, which remains intact after coating, was not responsible for producing the peak. In addition, the peak was observed in different parts of the nacre where the thickness of the individual aragonite platelets varied significantly, indicating that the inner multilayered microstructure of nacre did not contribute to the formation of this characteristic absorption. It is therefore here suggested that the characteristic UV band of the nacres of pearls and shells originates from the organic matrix in nacre. Given the established key role of the organic matrix in facilitating the unique brick-and-mortar architectures of nacre, which is known for its superior mechanical properties, the present study could potentially provide the basis for designing advanced optical and biomedical materials. [ABSTRACT FROM AUTHOR]

In this paper, Ag@FeO@cellulose nanocrystals (CNC) nanocomposites were synthesized by a facile and green microwave-assisted hydrothermal method. In the procedure, CNC was used as a reducing agent for the synthesis of Ag. During the whole synthesis process, there were no additional reducing agents or toxic solvents used. The nanocomposites were characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray spectrum, transmission electron microscopy, thermogravimetric analysis, and differential thermal analysis. In addition, Ag@FeO@CNC nanocomposites were also synthesized by microwave-assisted method and hydrothermal method. Both the effects of reaction time and synthetic procedures on the reduction process of Ag by CNC were explored. The results showed that FeO was formed with sphere-like structure and dispersed uniformly. Ag@FeO@CNC nanocomposites exhibited good adsorption of dye solution, which showed potential applications in water treatment. The antibacterial results showed that Ag@ FeO@CNC nanocomposites had good antibacterial activities toward both Staphylococcus aureus ( S. aureus) and Escherichia coli ( E. coli). The green and facile strategy reported in this paper may be broadly used in synthesizing other metal nanoparticles, as well as organic-inorganic nanocomposites. [ABSTRACT FROM AUTHOR]

The ligament of bivalve molluscs is known for its exceptional mechanical properties. In the present work, we investigated the nanoscale structure and composition of the aragonite fibers in the inner ligament of the freshwater shell Hyriopsis Cumingii, using high-resolution transmission electron microscope coupled with selected area electron diffraction, field-emission scanning electron microscope, and X-ray diffraction. The sample was found to exhibit cobble-like nanograins that were the basic building blocks to construct individual needle-shaped aragonite fibers in the ligament, which are generally different in sizes and shapes. The individual aragonite fibers were confirmed to be polycrystalline. In addition, twin stacking faults have been observed in the aragonite fibers of the ligament. These newly identified structural properties enhance our understanding of the formation mechanisms of bivalve ligaments and provide new guidelines to design and synthesis advanced functional materials for biomedical applications. [ABSTRACT FROM AUTHOR]

A facile and palladium-free process for the electroless plating on poly(vinyl chloride) (PVC) plastic has been demonstrated. The process is based on the Cu adsorption capacity of semi-interpenetrating polymer network (semi-IPN) hydrogel chemically bonded to PVC surface via a simple and one-step approach that applying a chitosan/polyethylene glycol/glutaraldehyde system under mild stirring at room temperature. Therefore, electroless plating can be achieved in the following three steps, namely: (1) the functionalization of PVC by the semi-IPN hydrogel film (2) the adsorption and formation of the catalyst Cu0 on the PVC surface, and (3) the electroless nickel plating in plating bath. Batch adsorption experiments are conducted to determine the effects of pH, initial Cu2+ ions concentration and the dosage of crosslinking agent glutaraldehyde on copper adsorption and the surface resistance of the corresponding plated-PVC. The activated reaction progress and resulting nickel-phosphorus (Ni-P) layer were characterized by attenuated total reflection Fourier transform infrared, scanning electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The results show that the Cu nanoparticles chemisorbed on the functionalized PVC substrate, could effectively initial the subsequent electroless nickel plating; and a compact and continuous Ni-P layer with amorphous phase was successfully deposited on PVC by this process. Besides, the surface resistance of the plated-PVC as low as 0.5 Ω sq-1 showed an excellent adhesion with the PVC substrate proved by Scotch-tape test. [ABSTRACT FROM AUTHOR]