Metallic zinc anodes in zinc‐ion batteries suffer from problematic Zn dendrite chemistry. Previous works have shown that preferred‐orientation crystal planes can help dendrite‐free metal anodes. This ...work reports a nanothickness (≈570 nm) AgZn3 coating to regulate the Zn growth. First, AgZn3@Zn anode avoids the problem, in Ag@Zn anode, that the rate of electrochemical Ag‐Zn alloying is slower than that of Zn dendrites growth. Batteries life increased from 112 h (pure Zn) and 932 h (Ag@Zn) to 1360 h (AgZn3@Zn) at 2 mA cm−2 and 1 mAh cm−2. Then, plasma sputtering can remove nonconductive ZnO and improve Zn‐ion affinity, which brings a longer life for AuZn3@Zn (423 h), CuZn3@Zn (385 h), and AgZn3@Zn (1150 h) than pure Zn (93 h) at 1 mAh cm−2. More importantly, AgZn3 (002) has a high matching with the Zn (002), which can guide ordered Zn epitaxial deposition, thereby achieving dense and dendrite‐free Zn growth. This work clearly captures the fascinating structure of the densely stacked Zn layers on the AgZn3 layer. This strategy not only improves the performance of zinc‐ion batteries greatly but will also help one understand the matching mechanism of the (002) vertical crystal plane.
A thin and uniform AgZn3 coating is obtained on Zn foils by Ar plasma sputtering, and is used as the metal anode of aqueous zinc‐ion batteries. Due to its unique vertical crystal plane matching mechanism between AgZn3 (002) and Zn (002), dense and plate Zn deposition and long battery cycle life are achieved.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Recently, sensors that can imitate human skin have received extensive attention. Capacitive sensors have a simple structure, low loss, no temperature drift, and other excellent properties, and can be ...applied in the fields of robotics, human–machine interactions, medical care, and health monitoring. Polymer matrices are commonly employed in flexible capacitive sensors because of their high flexibility. However, their volume is almost unchanged when pressure is applied, and they are inherently viscoelastic. These shortcomings severely lead to high hysteresis and limit the improvement in sensitivity. Therefore, considerable efforts have been applied to improve the sensing performance by designing different microstructures of materials. Herein, two types of sensors based on the applied forces are discussed, including pressure sensors and strain sensors. Currently, five types of microstructures are commonly used in pressure sensors, while four are used in strain sensors. The advantages, disadvantages, and practical values of the different structures are systematically elaborated. Finally, future perspectives of microstructures for capacitive sensors are discussed, with the aim of providing a guide for designing advanced flexible and stretchable capacitive sensors via ingenious human‐made microstructures.
The advantages, disadvantages, and practical applications of several popular microstructures that are widely employed in capacitive sensors are summarized. A microstructured dielectric layer or electrode can improve sensor sensitivity, reduce hysteresis, and endow the rigid electronic device with excellent elastic stretchability, which is an essential part of next‐generation wearable devices and soft robots.
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Graphene-based vertical heterostructures, particularly stacks incorporated with other layered materials, are promising for nanoelectronics. The stacking of two model Dirac materials, graphene and ...topological insulator, can considerably enlarge the family of van der Waals heterostructures. Despite good understanding of the two individual materials, the electron transport properties of a combined vertical heterojunction are still unknown. Here, we show the experimental realization of a vertical heterojunction between Bi2Se3 nanoplate and monolayer graphene. At low temperatures, the electron transport through the vertical heterojunction is dominated by the tunneling process, which can be effectively tuned by gate voltage to alter the density of states near the Fermi surface. In the presence of a magnetic field, quantum oscillations are observed due to the quantized Landau levels in both graphene and the two-dimensional surface states of Bi2Se3. Furthermore, we observe an exotic gate-tunable tunneling resistance under high magnetic field, which displays resistance maxima when the underlying graphene becomes a quantum Hall insulator.
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IJS, KILJ, NUK, PNG, UL, UM
Residence of cancer-propagating cells (CPCs) within preferential microenvironmental niches has a major part in evading therapy. However, the nature of niches involved and the mechanisms protecting ...CPCs remain largely unknown. We addressed these issues in mouse transplantation models of acute lymphoblastic leukemia (ALL). When the engrafted leukemic cells substantially damaged adjacent microenvironment in the bone marrow (BM), after chemotherapy small foci of CPCs were retained, surrounded by sheaths of supporting cells that comprise a protective niche. We investigated patients’ BM biopsies and found evidence of a similar process in patients receiving induction therapy. The efficacy of chemotherapy was enhanced by interfering with the niche formation or function. We therefore identified a therapy-induced niche that protects CPCs.
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•A therapy-induced niche created by surviving LPCs is identified in the bone marrow•LPC-secreted cytokines recruit and modify Nestin+ MSCs to build the niche•The niche provides Furin to process GDF15 that confers chemoresistance on LPCs•The niche is associated with failure to achieve complete remission in ALL patients
Microenvironmental niches can protect cancer-propagating cells from therapy and thus facilitate cancer relapse. Duan et al. examine conditions for niche formation and identify molecular players within such a microenvironment that support acute lymphoblastic leukemia cell survival.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Reversible covalent polymers are able to change their bond arrangement and structure via reversible reaction triggered by external stimuli including heating, light and pH, while retaining the ...stability of irreversible covalent polymers in the absence of the stimuli. In recent years, more and more research has been devoted to utilization of reversible covalent bonds in synthesizing new materials, which not only overcomes disadvantages of permanent covalent polymers, but also brings in new functionalities. More importantly, a series of novel techniques dedicated to polymerized products with features such as properties regulation, self-healing, reprocessing, solid state recycling, and controllable degradation are developed, heralding the opportunity of upgrading of traditional polymer engineering. Although the exploration of this emerging topic is still in its infancy, the advances so far are encouraging and clearly directed to large scale applications. This review systematically outlines this promising trend, following a bottom-up strategy, taking into account both theoretical and experimental achievements. It mainly consists of four parts, involving design and preparation: (i) the basis of reversible covalent chemistry, (ii) rheology of reversible covalent polymers, (iii) methods of construction of reversible covalent polymers, and (iv) smart, adaptive properties offered by reversible covalent chemistry. The key elements for realizing reorganization of polymers containing reversible covalent bonds are covered. The advantages and weaknesses of representative reaction systems are analyzed, while the challenges and opportunities to engineering application of the equilibrium control based on reversible covalent chemistry for producing end-use polymers are summarized. In this way, the readers may grasp both the overall situation as well as insight into future work.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Since December 2019, an epidemic caused by novel coronavirus (2019-nCoV) infection has occurred unexpectedly in China. As of 8 pm, 31 January 2020, more than 20 pediatric cases have been reported in ...China. Of these cases, ten patients were identified in Zhejiang Province, with an age of onset ranging from 112 days to 17 years. Following the latest
National recommendations for diagnosis and treatment of pneumonia caused by 2019-nCoV
(the 4th edition) and current status of clinical practice in Zhejiang Province, recommendations for the diagnosis and treatment of respiratory infection caused by 2019-nCoV for children were drafted by the National Clinical Research Center for Child Health, the National Children’s Regional Medical Center, Children’s Hospital, Zhejiang University School of Medicine to further standardize the protocol for diagnosis and treatment of respiratory infection in children caused by 2019-nCoV.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Radical aryl migration reactions are of particular interest to the chemical community due to their potential application in radical chemistry and organic synthesis. The neophyl rearrangements used as ...radical clocks for examining the radical-molecular reactions have been known for decades. The combinations of these migrations with other radical reactions have provided a wide range of novel synthetic methodologies that are complementary to nucleophilic rearrangements. This review will give an overview of various types of radical aryl migrations, with an emphasis on their mechanistic studies from a historical point of view, as well as their application in tandem radical reactions.
This review provides a comprehensive summary of radical aryl migration reactions, highlighting their mechanistic studies and synthetic applications.
Tandem jump: A novel copper‐catalyzed tandem trifluoromethylation/semipinacol rearrangement reaction of allylic alcohols has been achieved under mild conditions. This reaction is valuable for the ...difunctionalization of alkenes through simultaneous construction of a C sp 3CF3 bond and a quaternary carbon center, and could provide a straightforward strategy for the preparation of α‐quaternary β‐trifluoromethyl ketone derivatives.
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Stimuli‐responsive polymers built by reversible covalent bonds used to possess unbalanced mechanical properties. Here, a crosslinked polyurethane containing aromatic pinacol as a novel reversible CC ...bond provider is synthesized, whose tensile strength and failure strain are tunable from 27.3 MPa to as high as 115.2 MPa and from 324% to 1501%, respectively, owing to the relatively high bond energy of the CC bond of pinacol as well as the hydrogen bond between hard segments and semicrystalline soft segments. Moreover, the dynamic equilibrium of pinacol enables self‐healing and recycling of the polymer. Interestingly, the dynamic exchange among macromolecules, for the first time, successfully cooperates with solid‐state drawing that applies to thermoplastics, realizing strengthening of thermoset. Meanwhile, the radicals derived from homolysis of pinacol can repeatedly initiate polymerization of vinyl monomers. The fruitful outcomes of this work may create a series of promising new techniques.
The CC bond of pinacol is dynamically reversible at moderate temperature. A crosslinked polyurethane carrying pinacol unit is synthesized, which can be self‐healed, reprocessed, and recycled via the catalyst‐free reversible homolysis/radicals recombination of the CC bond. Moreover, its strength can be greatly improved by solid‐state drawing. The radicals created during homolysis are enabled to repeatedly initiate polymerization of vinyl monomers.
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