Local Structure in α-BIMEVOXes (ME = Ge, Sn).

The BIMEVOXes are among the best oxide ion conductors at low and intermediate temperatures. Their high conductivity is associated with local defect structure. In this work, the local structures of two BIMEVOX compositions, Bi2V0.9Ge0.1O5.45 and Bi2V0.95Sn0.05O5.475, are examined using total neutron and X-ray scattering methods, with both compositions exhibiting the ordered α-phase at 25 °C and the disordered γ-phase at 700 °C. While the diffraction data for the α-phase do not allow for the polar (C2) and nonpolar (C2/m) structures to be readily distinguished, measurements of dielectric permittivity suggest the α-phase is weakly ferroelectric in character, consistent with calculations of spontaneous polarization based on a combination of density functional calculations and machine learning methodology. Reverse Monte Carlo (RMC) analysis of total scattering data reveals Ge preferentially adopts tetrahedral geometry at both temperatures, while Sn is found to predominantly adopt octahedral coordination in the α-phase and tetrahedral coordination in the γ-phase. In all cases, V polyhedra are found to consist of tetrahedral, pentacoordinate, and octahedral geometries, as also predicted by the crystallographic analysis and confirmed by 51V solid state NMR spectroscopy. Although similar long-range structures are observed at room temperature, the oxide ion vacancy distributions were found to be quite different between the two studied compositions, with a nonrandom deficiency in vacancy pairs in the second-nearest shell along the ⟨100⟩ tetragonal direction for BIGEVOX10, compared with a long-distance (>8.0 Å) ordering of equatorial vacancies for BISNVOX05. This is attributed to the differences in the preferred coordination geometries of the substituent cations in the two systems. Impedance spectroscopy measurements reveal both compositions show high conductivity in the order of 10-1 S cm-1 at 600 °C.

Cl-/SO32--Codoped Poly(3,4-ethylenedioxythiophene) That Interpenetrates and Encapsulates Porous Fe2O3 To Form Composite Nanoframeworks for Stable Lithium-Ion Batteries.

Penetrating into the inner surface of porous metal-oxide nanostructures to encapsulate the conductive layer is an efficient but challenging route to exploit high-performance lithium-ion battery electrodes. Furthermore, if the bonding force on the interface between the core and shell was enhanced, the structure and cyclic performance of the electrodes will be greatly improved. Here, vertically aligned interpenetrating encapsulation composite nanoframeworks were assembled from Cl-/SO32--codoped poly(3,4-ethylenedioxythiophene) (PEDOT) that interpenetrated and coated on porous Fe2O3 nanoframeworks (PEDOT-IE-Fe2O3) via a one-step Fe3+-induced in situ growth strategy. Compared with conventional wrapped structures and methods, the special PEDOT-IE-Fe2O3 encapsulation structure has many advantages. First, the codoped PEDOT shell ensures a high conductive network in the composites (100.6 S cm-1) and provides interpenetrating fast ion/electron transport pathways on the inner and outer surface of a single composite unit. Additionally, the pores inside offer void space to buffer the volume expansion of the nanoscale frameworks in cycling processes. In particular, the formation of Fe-S bonds on the organic-inorganic interface (between PEDOT shell and Fe2O3 core) enhances the structural stability and further extends the cell cycle life. The PEDOT-IE-Fe2O3 was applied as lithium-ion battery anodes, which exhibit excellent lithium storage capability and cycling stability. The capacity was as high as 1096 mA h g-1 at 0.05 A g-1, excellent rate capability, and a long and stable cycle process with a capacity retention of 89% (791 mA h g-1) after 1000 cycles (2 A g-1). We demonstrate a novel interpenetrating encapsulation structure to highly enhance the electrochemical performance of metal-oxide nanostructures, especially the cycling stability, and provide new insights for designing electrochemical energy storage materials.

Distinct Patterns of PPARγ Promoter Usage, Lipid Degradation Activity, and Gene Expression in Subcutaneous Adipose Tissue of Lean and Obese Swine.

Subcutaneous adipose tissue is a loose connective tissue specializing in the regulation of energy storage and metabolization. In domesticated pigs (Sus scrofa), the temporal development of subcutaneous adipose tissue is critical for meat production. However, the regulation of adipose tissue development remains unclear. Here, the subcutaneous adipose tissue development was characterized and compared in lean (Danish-Landrace) and obese (Min) pigs at juvenile and the juvenile-to-adult growth stages. Using RNA sequencing, we profiled the transcriptome of subcutaneous adipose tissue isolated from 4- and 16-week-old pigs and identified 24,718 expressed transcription units. Of them, 6327 genes were differentially expressed between the breeds and/or developmental stages. Compared with obese pigs, upregulated genes in lean pigs showed significant function and pathway enrichment in fatty acid degradation and mitochondrial functions. Further analysis uncovered the distinct usage preferences of the three alternative peroxisome proliferator-activated receptor γ (PPARγ) promoters associated with the development of subcutaneous adipose tissue in both breeds. Transcriptome analysis of subcutaneous adipose tissue in lean and obese pigs suggested that marker-assisted selection of fatty acid degradation and PPARγ signaling pathways could be important directions for future pork quality improvement and modern breeding.

Controllable Synthesis of Tunable Microstructures of Self-Supporting Graphene Films from Opened Bubble to Cube via in Situ Template-Modulating.

Three-dimensional (3D) microstructured building units have replaced layer-to-layer stacked designs in transparent graphene films to fully exploit the advantages of two-dimensional graphene. However, it is still challenging to precisely control the size and microstructures of these building blocks to develop multifunctional graphene-based materials that satisfy the performance requirements of diverse applications. In this study, we propose a controllable method to regulate the microstructures of building units to form structures ranging from opened bubbles and cubes, while the size decreased from 20 to 3 µm, via an in situ template-modulating technology. NaCl was used as either a liquid or solid template by changing the dc bias. The reduced size and dense arrangement of the building units not only provide an improved mass loading for the transparent films but also build multiple pathways for fast ion/electron transmission, enhancing their promise for various practical applications. Generally, we provide a convenient protocol for finely regulating the microstructure and size of these building units, resulting in multifunctional films with a controllable transmittance, which enables the use of these graphene-based architectures as transparent electrodes in various applications and extends the family of multifunctional materials that will present new possibilities for electronics and other devices.

Transparent and Self-Supporting Graphene Films with Wrinkled- Graphene-Wall-Assembled Opening Polyhedron Building Blocks for High Performance Flexible/Transparent Supercapacitors.

Improving mass loading while maintaining high transparency and large surface area in one self-supporting graphene film is still a challenge. Unfortunately, all of these factors are absolutely essential for enhancing the energy storage performance of transparent supercapacitors for practical applications. To solve the above bottleneck problem, we produce a novel self-supporting flexible and transparent graphene film (STF-GF) with wrinkled-wall-assembled opened-hollow polyhedron building units. Taking advantage of the microscopic morphology, the STF-GF exhibits improved mass loading with high transmittance (70.2% at 550 nm), a large surface area (1105.6 m2/g), and good electrochemical performance: high energy (552.3 µWh/cm3), power densities (561.9 mW/cm3), a superlong cycle life, and good cycling stability (the capacitance retention is ∼94.8% after 20,000 cycles).

Symmetric transparent and flexible supercapacitor based on bio-inspired graphene-wrapped Fe2O3 nanowire networks.

Transition metal oxides with high specific capacitance materials are ideal for a new generation of high-performance transparent supercapacitors but are rarely reported. Commonly, the synthesis of the required nanostructured materials is a crucial step required to achieve the transparency of the device. In this study, a Fe2O3 nanowire network transparent film is developed simply through air-solution interface reactions and wrapped in graphene shells for use as transparent electrodes. The Fe2O3 nanowire networks surrounded by the graphene layer exhibit an effective encapsulation structure, providing rapid three-dimensional electron and ion transport pathways. The specific areal capacitance (3.3 mF cm-2 at a scan rate of 10 mV s-1) was greatly improved, which is at least one hundred times higher than that for transparent devices based on planar chemical vapor deposition graphene. Furthermore, the films have a power density of 191.3 W cm-3, which is higher than that of electrolytic capacitors, an energy density of 8 mWh cm-3, which is comparable to that of lithium thin-film batteries, and superior cycling stability.