Extracellular vesicles are a heterogeneous group of cell-derived membranous structures comprising exosomes and microvesicles, which originate from the endosomal system or which are shed from the plasma membrane, respectively They are present in biological fluids and are involved in multiple physiological and pathological processes Extracellular vesicles are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material Knowledge of the cellular processes that govern extracellular vesicle biology is essential to shed light on the physiological and pathological functions of these vesicles as well as on clinical applications involving their use and/or analysis However, in this expanding field, much remains unknown regarding the origin, biogenesis, secretion, targeting and fate of these vesicles

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Shedding light on the cell biology of extracellular vesicles.

The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review.

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

Nitrogen (N)-doped carbon materials exhibit high electrocatalytic activity for the oxygen reduction reaction (ORR), which is essential for several renewable energy systems. However, the ORR active site (or sites) is unclear, which retards further developments of high-performance catalysts. Here, we characterized the ORR active site by using newly designed graphite (highly oriented pyrolitic graphite) model catalysts with well-defined π conjugation and well-controlled doping of N species. The ORR active site is created by pyridinic N. Carbon dioxide adsorption experiments indicated that pyridinic N also creates Lewis basic sites. The specific activities per pyridinic N in the HOPG model catalysts are comparable with those of N-doped graphene powder catalysts. Thus, the ORR active sites in N-doped carbon materials are carbon atoms with Lewis basicity next to pyridinic N.

Active sites of nitrogen-doped carbon materials for oxygen reduction reaction clarified using model catalysts

The recent advances in electrocatalysis for oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs) are thoroughly reviewed. This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core–shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts, and metal-free catalysts. The recent development of ORR electrocatalysts with novel structures and compositions is highlighted. The understandings of the correlation between the activity and the shape, size, composition, and synthesis method are summarized. For the carbon-based materials, their performance and stability in fuel cells and comparisons with those of platinum are documented. The research directions as well as perspectives on the further development of more active and less expensive electrocatalysts are provided.

http://repository.ust.hk/ir/bitstream/1783.1-77094/1/acs.chemrev.5b00462_withlink.pdf

Recent Advances in Electrocatalysts for Oxygen Reduction Reaction

Hybrid organic–inorganic perovskite (HOIP) materials have caught significant attention in photovoltaics and photoelectronics for their outstanding photovoltaic properties. However, their instability to various environment, such as illumination, temperature, moisture and oxygen, hinders their way to commercialization. To figure out the interaction mechanism between H2O and CH3NH3PbI3 (MAPbI3), extensive theoretical studies have been carried out; however, the experimental results are insufficient and inconsistent. Here, we systematically investigate and compare the influence of H2O on MAPbI3 perovskite films with or without DMF) post-annealing in dark or light condition. The interaction between H2O and the surface of pristine MAPbI3 leads to the fusion of grain boundaries thus grain growth into micron level in short-time moisture exposure. While the penetration of H2O into MAPbI3 results in swelled crystalline whisker, cracking into smaller grains in long-time exposure upon the release of H2O. However, no degradation occurs in dark condition. As the DMF post-annealing treatment changes the surface states of MAPbI3, the interactions between the external H2O and internal MAPbI3 significantly varies from the pristine MAPbI3. Three different surface states with different topographies have influence on the interaction process and mechanism with H2O, leading to different decomposition rates, the striped surface that is the most rough among the three and experiencing the minimum change in surface potential with exposure to 80% humidity decomposes into PbI2 fastest. However, the addition of light will once again affect the aforementioned process. It is found that even ambient light could severely speed up the moisture-induced decomposition of MAPbI3, while the N,N-dimethylformamide (DMF) post-annealing treatment significantly improves the stability of MAPbI3 films upon exposure to humidity and illumination, benefiting from the MAI-deficient thus H2O resistant surface.

Microscopic investigations on the surface-state dependent moisture stability of a hybrid perovskite.

A new two-dimensional (2D) layered oxysulfide, namely, SrOCuSbS2, was successfully synthesized at 160 °C by using a hydrazine-hydrothermal method. The compound crystallizes in the space group C2h2-...

Enhanced Photoelectric SrOCuSbS2 of a [SrO]-Intercalated CuSbS2 Structure.

Ultrasmall Ag nanocrystals supported on chitosan/PVA nanofiber mats with bifunctional properties

Shanghai soft X-ray free-electron laser facility (SXFEL) is the first coherent X-ray light source in China with the shortest wavelength down to 2 nm. SXFEL is based on a 1.5 GeV C-band linac, including one seeded FEL line, one self-amplified spontaneous emission FEL line and five experimental stations. The development of SXFEL is in two stages, the test facility SXFEL-TF and the user facility SXFEL-UF. SXFEL-TF is based on a 0.84 GeV linac, aiming to master the key technologies of a cascaded FEL with high gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) scheme. Meanwhile, the object of SXFEL-UF is to start user operation at the end of 2019. This paper presents the design, construction and commissioning status of SXFEL. © 2019, Chinese Lasers Press. All right reserved.

Shanghai Soft X-Ray Free-Electron Laser Facility

Background: Panax notoginseng is an important Chinese medicinal plant. Dammarene-type triterpenoid saponins are main pharmacologically effective compounds in P. notoginseng. This study aims to investigate the formation and accumulation of saponins in P. notoginseng roots during germination and juvenile stage. Methods: P. notoginseng seeds were collected and stored in wet sand. After germination, the seedlings were transplanted into a soil nursery bed and cultivated for one year. During this period, samples were collected every month and the concentrations of ginsengnosides Rg1, Re, Rb1, Rd and notoginsengnoside R1 were determined by HPLC. Results: There was little saponin in the P. notoginseng seed. The chemical composition of seed was different from that of root. After germination, Rb1 ,R g1, Re, Rd and R1 appeared successively in the seedling root. And in the fivemonth-old root, all these five main saponins came into existence. The accumulation of saponins in P. notoginseng root was affected by seasons. Conclusion: The accumulation of saponins showed a time-dependent increase after germination of P. notoginseng.

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Dong Wang

Papers

Microscopic investigations on the surface-state dependent moisture stability of a hybrid perovskite.

Enhanced Photoelectric SrOCuSbS2 of a [SrO]-Intercalated CuSbS2 Structure.

Ultrasmall Ag nanocrystals supported on chitosan/PVA nanofiber mats with bifunctional properties

Shanghai Soft X-Ray Free-Electron Laser Facility

Saponin accumulation in the seedling root of Panax notoginseng