Co-Assembly of Soft and Hard Nanoparticles into Macroscopic Colloidal Composites with Tailored Mechanical Property and Processability.

Colloidal composites, translating the great potential of nanoscale building bricks into macroscopic dimensions, have emerged as an appealing candidate for new materials with applications in optics, energy storage, and biomedicines. However, it remains a key challenge to bridge the size regimes from nanoscopic colloidal particles to macroscale composites possessing mechanical robustness. Herein, a bottom-up approach is demonstrated to manufacture colloidal composites with customized macroscopic forms by virtue of the co-assembly of nanosized soft polymeric micelles and hard inorganic nanoparticles. Upon association, the hairy micellar corona can bind with the hard nanoparticles, linking individual hard constituents together in a soft-hard alternating manner to form a collective entity. This permits the integration of block copolymer micelles with controlled amounts of hard nanoparticles into macroscopic colloidal composites featuring diverse internal microstructures. The resultant composites showed tunable microscale mechanical strength in a range of 90-270 MPa and macroscale mechanical strength in a range of 7-42 MPa for compression and 2-24 MPa for bending. Notably, the incorporation of soft polymeric micelles also imparts time- and temperature-dependent dynamic deformability and versatile capacity to the resulting composites, allowing their application in the low-temperature plastic processing for functional fused silica glass.

Promotion of the Nucleation of Ultrafine Ni-Rich Layered Oxide Primary Particles by an Atomic Layer-Deposited Thin Film for Enhanced Mechanical Stability.

Understanding the atomistic mechanisms of non-equilibrium processes during solid-state synthesis, such as nucleation and grain structure formation of a layered oxide phase, is a critical challenge for developing promising cathode materials such as Ni-rich layered oxide for Li-ion batteries. In this study, we found that the aluminum oxide coating layer transforms into lithium aluminate as an intermediate, which has favorable low interfacial energies with the layered oxide to promote the nucleation of the latter. The fast and uniform nucleation and formation of the layered oxide phase at relatively low temperatures were evidenced using solid-state nuclear magnetic resonance and in situ synchrotron X-ray diffraction. The resulting Ni-rich layered oxide cathode has fine primary particles, as visualized by three-dimensional tomography constructed using a focused-ion beam and scanning electron microscopy. The densely packed fine primary particles enable the excellent mechanical strength of the secondary particles, as demonstrated by in situ compression tests. This strategy provides a new approach for developing next-generation, high-strength battery materials.

Exploration of Hierarchical Metal-Organic Framework as Ultralight, High-Strength Mechanical Metamaterials.

Due to the extraordinarily high surface to volume ratio and enormous structural and chemical diversities, metal-organic frameworks (MOFs) have drawn much attention in applications such as heterogeneous catalysis, gas storage separation, and drug delivery, and so on. However, the potential of MOF materials as mechanical metamaterials has not been investigated. In this work, we demonstrated that through the concerted effort of molecular construct and mesoscopic structural design, hierarchical MOFs can exhibit superb mechanical properties. With the cutting-edge in situ transmission and scanning electron microscope (TEM and SEM) techniques, the mechanical properties of hollow UiO-66 octahedron particles were quantitatively studied by compression on individual specimens. Results showed that the yield strength and Young's modulus of the hierarchical porous framework material presented a distinct "smaller is stronger and stiffer" size dependency, and the maximum yield strength and Young's modulus reached 580 ± 55 MPa and 4.3 ± 0.5 GPa, respectively. The specific strengths were measured as 0.15 ± 0.03 to 0.68 ± 0.11 GPa g-1 cm3, which is comparable to the previously reported state-of-the-art mechanical metamaterials like glassy carbon nanolattices and pyrolytic carbon nanolattices. This work revealed that MOF materials can be made into a new class of low-density, high-strength mechanical metamaterials and provided insight into the mechanical stability of nanoscale MOFs for practical applications.

Piezoelectrically enhanced photocatalysis of KxNa1-xNbO3 (KNN) microstructures for efficient water purification.

As a kind of excellent multifunctional metal oxide semiconductor, KxNa1-xNbO3 (KNN) has been widely applied in a variety of fields such as photocatalysis and energy harvesting due to its excellent piezoelectric, dielectric and photovoltaic properties in recent decades. In this report, octahedron-shaped K0.4Na0.6NbO3 (KNN-6) microstructures assembled by cubic nanoparticles with {010} exposed facets were synthesized via a one-pot hydrothermal reaction. Due to the accumulation of electrons on the exposed facets, which was conducive to the separation of photo-generated electron-hole pairs, the microstructures could achieve a highly efficient photocatalytic performance for wastewater degradation. In addition, owing to the piezoelectric effect of KNN crystals, the degradation efficiency could be further enhanced by introducing ultrasonic vibration. Using methylene blue (MB) as the organic dye to evaluate their wastewater degradation efficiency, the KNN microstructures achieved their best catalytic performance when the atomic ratio of KOH to NaOH in the reactant was set at 4 : 6 (KNN-6). Under the synergistic effect of light irradiation and ultrasonic vibration, MB could almost be completely (99%) degraded within 40 minutes by KNN-6 microstructures, which was several times more efficient than that of pure NaNbO3 or KNbO3 in previous reports. This work demonstrated that the K0.4Na0.6NbO3 (KNN-6) microstructure could be a prominent candidate for wastewater purification. The formation mechanism of KNN crystals and the role of the piezoelectric effect in the photocatalytic process were also discussed.

Nanohybrid of Co3O4 Nanoparticles and Polyphosphazene-Decorated Ultra-Thin Boron Nitride Nanosheets for Simultaneous Enhancement in Fire Safety and Smoke Suppression of Thermoplastic Polyurethane.

Thermoplastic polyurethane (TPU) is widely used in daily life due to its characteristics of light weight, high impact strength, and compression resistance. However, TPU products are extremely flammable and will generate toxic fumes under fire attack, threatening human life and safety. In this article, a nanohybrid flame retardant was designed for the fire safety of TPU. Herein, Co3O4 was anchored on the surface of exfoliated ultra-thin boron nitride nanosheets (BNNO@Co3O4) via coprecipitation and subsequent calcination. Then, a polyphosphazene (PPZ) layer was coated onto BNNO@Co3O4 by high temperature polymerization to generate a nanohybrid flame retardant named BNNO@Co3O4@PPZ. The cone calorimeter results exhibited that the heat release and smoke production during TPU combustion were remarkably restrained after the incorporation of the nanohybrid flame retardant. Compared with pure TPU, the peak heat release rate (PHRR) decreased by 44.1%, the peak smoke production rate (PSPR) decreased by 51.2%, and the peak CO production rate (PCOPR) decreased by 72.5%. Based on the analysis of carbon residues after combustion, the significant improvement in fire resistance of TPU by BNNO@Co3O4@PPZ was attributed to the combination of quenching effect, catalytic carbonization effect, and barrier effect. In addition, the intrinsic mechanical properties of TPU were well maintained due to the existence of the PPZ organic layer.

Facile Synthesis of BiVO4@ZIF-8 Composite with Heterojunction Structure for Photocatalytic Wastewater Treatment.

Water pollution has always been a serious problem across the world; therefore, facile pollutant degradation via light irradiation has been an attractive issue in the field of environmental protection. In this study, a type of Zn-based metal-organic framework (ZIF-8)-wrapped BiVO4 nanorod (BiVO4@ZIF-8) with high efficiency for photocatalytic wastewater treatment was synthesized through a two-step hydrothermal method. The heterojunction structure of BiVO4@ZIF-8 was confirmed by morphology characterization. Due to the introduction of mesoporous ZIF-8, the specific surface area reached up to 304.5 m2/g, which was hundreds of times larger than that of pure BiVO4 nanorods. Furthermore, the band gap of BiVO4@ZIF-8 was narrowed down to 2.35 eV, which enabled its more efficient utilization of visible light. After irradiation under visible light for about 40 min, about 80% of rhodamine B (RhB) was degraded, which was much faster than using pure BiVO4 or other BiVO4-based photocatalysts. The synergistic photocatalysis mechanism of BiVO4@ZIF-8 is also discussed. This study might offer new pathways for effective degradation of wastewater through facile design of novel photocatalysts.

A Reflection on the 2017 Nobel Prize for Physiology and Chinese Medicine.

Research on the molecular mechanisms controlling circadian rhythm in Western medicine is comparable to the study of a day-night rhythm in Chinese medicine (CM), as also focus on the same life phenomenon. By comparing the two, this paper elaborates on the differences between them in their respective issues of consciousness, ways of thinking, research methods and research results. Relatively speaking, Nobel Prize research has a stronger sense of the problems and concerns about the essence of "what", while CM focuses on "how a thing functions". The former mainly adopts experimental and mathematical methods, while the latter primarily depends on observation and understanding. The natural philosophy and natural science eventually lead to the results and the inevitable, quantitative and qualitative differences. Research on the life rhythm in CM should be proposed, scientific problems should be fully grasped, and research should be carried out with the aid of multidisciplinary new knowledge and new achievements through cross-disciplinary studies. On the basis of clinical epidemiological research and experimental research, a systematic review should be made of the human physiology of CM and the pathological rhythm model to explore the regulatory mechanism of time rhythm and create a new theory of time medicine.

[Research progress on Huang Fu-mi's A-B classic of acupuncture and moxibustion].

In order to understand the research status of HUANG Fu-mi's A-B Classic of Acupuncture and Moxibustion, 83 pieces of literature that have been publically published since 1978 were analyzed. A summary was performed according to 7 aspects including version origin, emendation, arrangement and summary, theory discussion, clinical research, value evaluation, the rest questions, etc. It is believed that deep research work has been done on explanations, emendation and translation regarding A-B Classic of Acupuncture and Moxibustion. However, the exploration work on the theory and application is far from enough. Therefore, beginning from historical and cultural background, we should analyze the humanistic spirit of HUANG Fu-mi combined with A-B Classic of Acupuncture and Moxibustion to perform a deep exploration, so we could have a thorough and comprehensive research on HUANG Fu-mi's academic thoughts.