Correlation between Li Plating Behavior and Surface Characteristics of Carbon Matrix toward Stable Li Metal Anodes

Carbonaceous materials are widely employed to host Li for stable and safe Li metal batteries while relatively little effort is devoted to tailoring the surface properties of carbon to facilitate uniform Li plating. Herein, the correlation between Li plating behavior and the surface characteristics of electrospun porous carbon nanofibers (PCNFs) is systemically elucidated through experiments and theoretical calculations. It is revealed that the neat carbon surface suffers from severe lattice mismatch with Li metal, hindering uniform Li plating. In contrast, open pores created on the PCNF surface serve as active sites for controlled initial nucleation of Li. The introduction of oxygenated functional groups further facilitates the nucleation of Li on PCNFs through the largely reduced nucleation energy barrier. The Li film uniformly deposited on PCNFs enables efficient use of the whole carbon surface, giving rise to enhanced cyclic stability of the electrode. When used as an anode in lithium–sulfur batteries, the modified electrode delivers an excellent energy density of 385 Wh kg^?1 after 100 cycles. The fundamental correlation established in this study is universal to all types of carbonaceous materials and sheds new light on the rational design of high‐performance Li metal anodes by controlling the initial Li nucleation.     

Sulfiphilic Few‐Layered MoSe2 Nanoflakes Decorated rGO as a Highly Efficient Sulfur Host for Lithium‐Sulfur Batteries

Lithium‐sulfur batteries (LSBs) have been regarded as a competitive candidate for next‐generation electrochemical energy‐storage technologies due to their merits in energy density. The sluggish redox kinetics of the electrochemistry and the high solubility of polysulfides during cycling result in insufficient sulfur utilization, severe polarization, and poor cyclic stability. Herein, sulfiphilic few‐layered MoSe₂ nanoflakes decorated rGO (MoSe₂@rGO) hybrid has been synthesized through a facile hydrothermal method and for the first time, is used as a conceptually new‐style sulfur host for LSBs. Specifically, MoSe₂@rGO not only strongly interacts with polysulfides but also dynamically strengthens polysulfide redox reactions. The polarization problem is effectively alleviated by relying on the sulfiphilic MoSe₂. Moreover, MoSe₂@rGO is demonstrated to be beneficial for the fast nucleation and uniform deposition of Li₂S, contributing to the high discharge capacity and good cyclic stability. A high initial capacity of 1608 mAh g^?1 at 0.1 C, a slow decay rate of 0.042% per loop at 0.25 C, and a high reversible capacity of 870 mAh g^?1 with areal sulfur loading of 4.2 mg cm^?2 at 0.3 C are obtained. The concept of introducing sulfiphilic transition‐metal selenides into the LSBs system can stimulate engineering of novel architectures with enhanced properties for various energy‐storage devices.     

Activity-Dependent Nucleation of Dynamic Microtubules at Presynaptic Boutons Controls Neurotransmission

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CTENO64 Is Required for Coordinated Paddling of Ciliary Comb Plate in Ctenophores

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Disassembly of Actin and Keratin Networks by Aurora B Kinase at the Midplane of Cleaving Xenopus laevis Eggs

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Centromere Dysfunction Compromises Mitotic Spindle Pole Integrity

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Acentriolar microtubule organization centers and Ran‐mediated microtubule formation pathways are both required in porcine oocytes

Mammalian oocytes lack centrioles but can generate bipolar spindles using several different mechanisms. For example, mouse oocytes have acentriolar microtubule organization centers (MTOCs) that contain many components of the centrosome, and which initiate microtubule polymerization. On the contrary, human oocytes lack MTOCs and the Ran‐mediated mechanisms may be responsible for spindle assembly. Complete knowledge of the different mechanisms of spindle assembly is lacking in various mammalian oocytes. In this study, we demonstrate that both MTOC‐ and Ran‐mediated microtubule nucleation are required for functional meiotic metaphase I spindle generation in porcine oocytes. Acentriolar MTOC components, including Cep192 and pericentrin, were absent in the germinal vesicle and germinal vesicle breakdown stages. However, they start to colocalize to the spindle microtubules, but are absent in the meiotic spindle poles. Knockdown of Cep192 or inhibition of Polo‐like kinase 1 activity impaired the recruitment of Cep192 and pericentrin to the spindles, impaired microtubule assembly, and decreased the polar body extrusion rate. When the Ran^GTP gradient was perturbed by the expression of dominant negative or constitutively active Ran mutants, severe defects in microtubule nucleation and cytokinesis were observed, and the localization of MTOC materials in the spindles was abolished. These results demonstrate that the stepwise involvement of MTOC‐ and Ran‐mediated microtubule assembly is crucial for the formation of meiotic spindles in porcine oocytes, indicating the diversity of spindle formation mechanisms among mammalian oocytes.     

PTEN modulates GDNF/RET mediated chemotaxis and branching morphogenesis in the developing kidney

The RET receptor tyrosine kinase is activated by GDNF and controls outgrowth and invasion of the ureteric bud epithelia in the developing kidney. In renal epithelial cells and in enteric neuronal precursor cells, activation of RET results in chemotaxis as Ret expressing cells invade the surrounding GDNF expressing tissue. One potential downstream signaling pathway governing RET mediated chemotaxis may require phosphatidylinositol 3-kinase (PI3K), which generates PI(3,4,5) triphosphate. The PTEN tumor suppressor gene encodes a protein and lipid phosphatase that regulates cell growth, apoptosis and many other cellular processes. PTEN helps regulate cellular chemotaxis by antagonizing the PI3K signaling pathway through dephosphorylation of phosphotidylinositol triphosphates. In this report, we show that PTEN suppresses RET mediated cell migration and chemotaxis in cell culture assays, that RET activation results in asymmetric localization of inositol triphosphates and that loss of PTEN affects the pattern of branching morphogenesis in developing mouse kidneys. These data suggest a critical role for the PI3K/PTEN axis in shaping the pattern of epithelial branches in response to RET activation.     

Dynamics of embryonic pancreas development using real-time imaging

Current knowledge about developmental processes in complex organisms has relied almost exclusively on analyses of fixed specimens. However, organ growth is highly dynamic, and visualization of such dynamic processes, e.g., real-time tracking of cell movement and tissue morphogenesis, is becoming increasingly important. Here, we use live imaging to investigate expansion of the embryonic pancreatic epithelium in mouse. Using time-lapse imaging of tissue explants in culture, fluorescently labeled pancreatic epithelium was found to undergo significant expansion accompanied by branching. Quantification of the real-time imaging data revealed lateral branching as the predominant mode of morphogenesis during epithelial expansion. Live imaging also allowed documentation of dynamic beta-cell formation and migration. During in vitro growth, appearance of newly formed beta-cells was visualized using pancreatic explants from MIP-GFP transgenic animals. Migration and clustering of beta-cells were recorded for the first time using live imaging. Total beta-cell mass and concordant aggregation increased during the time of imaging, demonstrating that cells were clustering to form "pre-islets". Finally, inhibition of Hedgehog signaling in explant cultures led to a dramatic increase in total beta-cell mass, demonstrating application of the system in investigating roles of critical embryonic signaling pathways in pancreas development including beta-cell expansion. Thus, pancreas growth in vitro can be documented by live imaging, allowing visualization of the developing pancreas in real-time.