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The high capacity of electrodes allows for a lower mass of electrodes, which is essential for increasing the energy density of the batteries. According to this, silicon is a promising anode candidate for Li-ion batteries due to its high theoretical capacity. However, its practical application is hampered by the significant volume expansion of silicon during battery operation, resulting in pulverization and contact loss. In this study, we developed a stable Li-ion anode that not only solves the problem of the short lifetime of silicon but also preserves the initial efficiency by using silicon nanoparticles covered with glassy ZIF-4 (SZ-4). SZ-4 suppresses silicon pulverization, contact loss, etc. because the glassy ZIF-4 wrapped around the silicon nanoparticles prevents additional SEI formation outside the silicon surface due to the electrically insulating characteristics of glassy ZIF-4. The SZ-4 realized by a simple heat treatment method showed 74% capacity retention after 100 cycles and a high initial efficiency of 78.7%.

Li metal is a promising anode candidate due to its high theoretical capacity and low electrochemical potential. However, dendrite formation and the resulting dead Li cause continuous Li consumption, which hinders its practical application. In this study, we realized N-doped nanoporous carbon for a stable Li metal host composed only of lightweight elements C and N through the simple calcination of a nitrogen-containing metal-organic framework (MOF). During the calcination process, we effectively controlled the amount of lithophilic N and the electrical conductivity of the N-doped porous carbons to optimize their performance as Li metal hosts. As a result, the N-doped porous carbon exhibited excellent electrochemical performances, including 95.8% coulombic efficiency and 91% capacity retention after 150 cycles in a full cell with an LFP cathode. The N-doped nanoporous carbon developed in this study can realize a stable Li metal host without adding lithium ion metals and metal oxides, etc., which is expected to provide an efficient approach for reliable Li metal anodes in secondary battery applications.

A two-dimensional (2D) atomic crystalline transition metal dichalcogenides has shown immense features, aiming for future nanoelectronic devices comparable to conventional silicon (Si). 2D molybdenum ditelluride (MoTe 2 ) has a small bandgap, appears close to that of Si, and is more favorable than other typical 2D semiconductors. In this study, we demonstrate laser-induced p-type doping in a selective region of n-type semiconducting MoTe 2 field effect transistors (FET) with an advance in using the hexagonal boron nitride as passivation layer from protecting the structure phase change from laser doping. A single nanoflake MoTe 2 -based FET, exhibiting initial n-type and converting to p-type in clear four-step doping, changing charge transport behavior in a selective surface region by laser doping. The device shows high electron mobility of about 23.4 cm 2 V -1 s -1 in an intrinsic n-type channel and hole mobility of about 0.61 cm 2 V -1 s -1 with a high on/off ratio. The device was measured in the range of temperature 77-300 K to observe the consistency of the MoTe 2 -based FET in intrinsic and laser-dopped region. In addition, we measured the device as a complementary metal-oxide-semiconductor (CMOS) inverter by switching the charge-carrier polarity of the MoTe 2 FET. This fabrication process of selective laser doping can potentially be used for larger-scale MoTe 2 CMOS circuit applications.

Due to the vulnerability of organic optoelectronic devices to moisture and oxygen, thin-film moisture barriers have played a critical role in improving the lifetime of the devices. Here, we propose a hexagonal boron nitride (hBN) embedded Al 2 O 3 thin film as a flexible moisture barrier. After layer-by-layer (LBL) staking of polymer and hBN flake composite layer, Al 2 O 3 was deposited on the nano-laminate template by spatial plasma atomic layer deposition (PEALD). Because the hBN flakes in Al 2 O 3 thin film increase the diffusion path of moisture, the composite layer has a low water vapor transmission ratio (WVTR) value of 1.8 × 10 -4 g/m 2 day. Furthermore, as embedded hBN flakes restrict crack propagation, the composite film exhibits high mechanical stability in repeated 3 mm bending radius fatigue tests.

We report a novel graphene transfer technique for fabricating graphene field-effect transistors (FETs) that avoids detrimental organic contamination on a graphene surface. Instead of using an organic supporting film like poly(methyl methacrylate) (PMMA) for graphene transfer, Au film is directly deposited on the as-grown graphene substrate. Graphene FETs fabricated using the established organic film transfer method are easily contaminated by organic residues, while Au film protects graphene channels from these contaminants. In addition, this method can also simplify the device fabrication process, as the Au film acts as an electrode. We successfully fabricated graphene FETs with a clean surface and improved electrical properties using this Au-assisted transfer method.

Manipulation of Ohmic contacts in 2D transition metal dichalcogenides for enhancing the transport properties and enabling its application as a practical device has been a long-sought goal. In this study, n-type tungsten disulfide (WS 2 ) single atomic layer to improve the Ohmic contacts of the p-type molybdenum ditelluride (MoTe 2 ) material is covered. The Ohmic properties, based on the lowering of Schottky barrier height (SBH) owing to the tunneling barrier effect of the WS 2 monolayer, are found to be unexpectedly excellent at room temperature and even at 100 K. The improved SBH and contact resistances are 3 meV and 1 MΩ µm, respectively. The reduction in SBH and contact resistance is confirmed with temperature-dependent transport measurements. This study further demonstrates the selective carrier transport across the MoTe 2 and WS 2 layers by modulating the applied gate voltage. This WS 2 /MoTe 2 heterostructure exhibits excellent gate control over the currents of both channels (n-type and p-type). The on/off ratios for both the electron and hole channels are calculated as 10 7 and 10 6 , respectively, indicating good carrier type modulation by the electric field of the gate electrode. The Ohmic contact resistance using the tunneling of the atomic layer can be applied to heterojunction combinations of various materials., (© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Li-ion batteries (LIBs) employ porous, composite-type electrodes, where few weight percentages of carbonaceous conducting agents and polymeric binders are required to bestow electrodes with electrical conductivity and mechanical robustness. However, the use of such inactive materials has limited enhancements of battery performance in terms of energy density and safety. In this study, we introduced graphene/polyvinylidene fluoride (Gr/PVdF) composites in Ni-rich oxide cathodes for LIBs, replacing conventional conducting agents, carbon black (CB) nanoparticles. By using Gr/PVdF suspensions, we fabricated highly dense LiNi 0.85 Co 0.15 Al 0.05 O 2 (NCA) cathodes having a uniform distribution of conductive Gr sheets without CB nanoparticles, which was confirmed by scanning spreading resistance microscopy mode using atomic force microscopy. At a high content of 99 wt.% NCA, good cycling stability was shown with significantly improved areal capacity (Q areal ) and volumetric capacity (Q vol ), relative to the CB/PVdF-containing NCA electrode with a commercial-level of electrode parameters. The NCA electrodes using 1 wt.% Gr/PVdF (0.9:0.1) delivered a high Q areal of ~3.7 mAh cm -2 (~19% increment) and a high Q vol of ~774 mAh cm -3 (~18% increment) at a current rate of 0.2 C, as compared to the conventional NCA electrode. Our results suggest a viable strategy for superseding conventional conducting agents (CB) and improving the electrochemical performance of Ni-rich cathodes for advanced LIBs., Competing Interests: The authors declare no conflicts of interest.

The energy storage performance of lithium-ion batteries (LIBs) depends on the electrode capacity and electrode/cell design parameters, which have previously been addressed separately, leading to a failure in practical implementation. Here, we show how conformal graphene (Gr) coating on Ni-rich oxides enables the fabrication of highly packed cathodes containing a high content of active material (~99 wt%) without conventional conducting agents. With 99 wt% LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) and electrode density of ~4.3 g cm -3 , the Gr-coated NCA cathode delivers a high areal capacity, ~5.4 mAh cm -2 (~38% increase) and high volumetric capacity, ~863 mAh cm -3 (~34% increase) at a current rate of 0.2 C (~1.1 mA cm -2 ); this surpasses the bare electrode approaching a commercial level of electrode setting (96 wt% NCA; ~3.3 g cm -3 ). Our findings offer a combinatorial avenue for materials engineering and electrode design toward advanced LIB cathodes.

We present the case of a patient with acute upper limb ischemia as the sole initial manifestation of severe acute respiratory syndrome associated with coronavirus disease 2 infection, without concomitant respiratory symptoms or pneumonia. Viral infection presumably precipitated the patient's thromboembolic event, causing multifocal vascular occlusions. This case illustrates that coronavirus disease-19 must be considered in the differential diagnosis of patients presenting with signs or symptoms of coagulopathy, even in the absence of respiratory symptoms. We believe that an awareness of the variety of clinical presentations in patients with coronavirus disease-19, particularly extrapulmonary manifestations, is critical for optimal patient management as well as implementation of appropriate infection prevention measures., (© 2020 The Authors.)

The competition between quality and productivity has been a major issue for large-scale applications of two-dimensional materials (2DMs). Until now, the top-down mechanical cleavage method has guaranteed pure perfect 2DMs, but it has been considered a poor option in terms of manufacturing. Here, we present a layer-engineered exfoliation technique for graphene that not only allows us to obtain large-size graphene, up to a millimeter size, but also allows selective thickness control. A thin metal film evaporated on graphite induces tensile stress such that spalling occurs, resulting in exfoliation of graphene, where the number of exfoliated layers is adjusted by using different metal films. Detailed spectroscopy and electron transport measurement analysis greatly support our proposed spalling mechanism and fine quality of exfoliated graphene. Our layer-engineered exfoliation technique can pave the way for the development of a manufacturing-scale process for graphene and other 2DMs in electronics and optoelectronics., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Flexible transparent conducting electrodes (FTCE) are an essential component of next-generation flexible optoelectronic devices. Graphene is expected to be a promising material for the FTCE, because of its high transparency, large charge carrier mobilities, and outstanding chemical and mechanical stability. However, the electrical conductivity of graphene is still not good enough to be used as the electrode of an FTCE, which hinders its practical application. In this study, graphene was heavily n -type doped while maintaining high transmittance by adsorbing amine-rich macromolecules to graphene. The n -type charge-transfer doping of graphene was maximized by increasing the density of free amine in the macromolecule through a vacuum annealing process. The graphene adsorbed with the n -type dopants was stacked twice, resulting in a graphene FTCE with a sheet resistance of 38 ohm/sq and optical transmittance of 94.1%. The figure of merit (FoM) of the graphene electrode is as high as 158, which is significantly higher than the minimum standard for commercially available transparent electrodes (FoM = 35) as well as graphene electrodes doped with previously reported chemical doping methods. Furthermore, the n -doped graphene electrodes not only show outstanding flexibility but also maintain the doping effect even in high temperature (500 K) and high vacuum (~10 -6 torr) conditions. These results show that the graphene doping proposed in this study is a promising approach for graphene-based next-generation FTCEs.

The electrical and optical properties of semiconducting transition metal dichalcogenides (TMDs) can be tuned by controlling their composition and the number of layers they have. Among various TMDs, the monolayer WSe 2 has a direct bandgap of 1.65 eV and exhibits p-type or bipolar behavior, depending on the type of contact metal. Despite these promising properties, a lack of efficient large-area production methods for high-quality, uniform WSe 2 hinders its practical device applications. Various methods have been investigated for the synthesis of large-area monolayer WSe 2 , but the difficulty of precisely controlling solid-state TMD precursors (WO 3 , MoO 3 , Se, and S powders) is a major obstacle to the synthesis of uniform TMD layers. In this work, we outline our success in growing large-area, high-quality, monolayered WSe 2 by utilizing methane (CH 4 ) gas with precisely controlled pressure as a promoter. When compared to the catalytic growth of monolayered WSe 2 without a gas-phase promoter, the catalytic growth of the monolayered WSe 2 with a CH 4 promoter reduced the nucleation density to 1/1000 and increased the grain size of monolayer WSe 2 up to 100 μm. The significant improvement in the optical properties of the resulting WSe 2 indicates that CH 4 is a suitable candidate as a promoter for the synthesis of TMD materials, because it allows accurate gas control.

Twisted bi-layer graphene (tBLG) has attracted much attention because of its unique band structure and properties. The properties of tBLG vary with small differences in the interlayer twist angle, but it is difficult to accurately adjust the interlayer twist angle of tBLG with the conventional fabrication method. In this study, we introduce a facile tBLG fabrication method that directly picks up a single-crystalline graphene layer from a growth substrate and places it on another graphene layer with a pre-designed twist angle. Using this approach, we stacked single-crystalline graphene layers with controlled twist angles and thus fabricated tBLG and twisted multi-layer graphene (tMLG). The structural, optical and electrical properties depending on the twist angle and number of layers, were investigated using transmission electron microscopy (TEM), micro-Raman spectroscopy, and gate-dependent sheet resistance measurements. The obtained results show that the pick and place approach enables the direct dry transfer of the top graphene layer on the as-grown graphene to fabricate uniform tBLG and tMLG with minimal interlayer contamination and pre-defined twist angles.

With increasing demand for high-capacity and rapidly rechargeable anodes, problems associated with unstable evolution of a solid-electrolyte interphase on the active anode surface become more detrimental. Here, we report the near fatigue-free, ultrafast, and high-power operations of lithium-ion battery anodes employing silicide nanowires anchored selectively to the inner surface of graphene-based micro-tubular conducting electrodes. This design electrically shields the electrolyte inside the electrode from an external potential load, eliminating the driving force that generates the solid-electrolyte interphase on the nanowire surface. Owing to this electric control, a solid-electrolyte interphase develops firmly on the outer surface of the graphene, while solid-electrolyte interphase-free nanowires enable fast electronic and ionic transport, as well as strain relaxation over 2000 cycles, with 84% capacity retention even at ultrafast cycling (>20C). Moreover, these anodes exhibit unprecedentedly high rate capabilities with capacity retention higher than 88% at 80C (vs. the capacity at 1C).

Rapid progress in two-dimensional (2D) crystalline materials has recently enabled a range of device possibilities. These possibilities may be further expanded through the development of advanced 2D glass materials. Zachariasen carbon monolayer, a novel amorphous 2D carbon allotrope, was successfully synthesized on germanium surface. The one-atom-thick continuous amorphous layer, in which the in-plane carbon network was fully sp 2 -hybridized, was achieved at high temperatures (>900°C) and a controlled growth rate. We verified that the charge carriers within the Zachariasen carbon monolayer are strongly localized to display Anderson insulating behavior and a large negative magnetoresistance. This new 2D glass also exhibited a unique ability as an atom-thick interface layer, allowing the deposition of an atomically flat dielectric film. It can be adopted in conventional semiconductor and display processing or used in the fabrication of flexible devices consisting of thin inorganic layers.

A facile approach was demonstrated for fabricating high-performance nonvolatile memory devices based on ferroelectric-gate field effect transistors using a p-type Si nanowire coated with omega-shaped gate organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)). We overcame the interfacial layer problem by incorporating P(VDF-TrFE) as a ferroelectric gate using a low-temperature fabrication process. Our memory devices exhibited excellent memory characteristics with a low programming voltage of ±5 V, a large modulation in channel conductance between ON and OFF states exceeding 10 5 , a long retention time greater than 3 × 10 4 s, and a high endurance of over 10 5 programming cycles while maintaining an I ON / I OFF ratio higher than 10 2 .

Due to its direct and narrow band gap, high chemical stability, and high Seebeck coefficient (1800 μVK(-1)), antimony selenide (Sb2Se3) has many potential applications, such as in photovoltaic devices, thermoelectric devices, and solar cells. However, research on the Sb2Se3 materials has been limited by its low electrical conductivity in bulk state. To overcome this challenge, we suggest two kinds of nano-structured materials, namely, the diameter-controlled Sb2Se3 nanowires and Ag2Se-decorated Sb2Se3 nanowires. The photocurrent response of diameter-controlled Sb2Se3, which depends on electrical conductivity of the material, increases non-linearly with the diameter of the nanowire. The photosensitivity factor (K = I(light)/I(dark)) of the intrinsic Sb2Se3 nanowire with diameter of 80-100 nm is highly improved (K = 75). Additionally, the measurement was conducted using a single nanowire under low source-drain voltage. The dark- and photocurrent of the Ag2Se-decorated Sb2Se3 nanowire further increased, as compared to that of the intrinsic Sb2Se3 nanowire, to approximately 50 and 7 times, respectively.

There are limited data examining whether outcomes of methicillin-resistant Staphylococcus aureus (MRSA) healthcare-associated infections (HAIs) are worse when caused by community-associated (CA) strains compared to HA strains. We reviewed all patients' charts at our institution from 1999 to 2009 that had MRSA first isolated only after 72 h of hospitalization (n=724). Of these, 384 patients had a MRSA-HAI according to CDC criteria. Treatment failure was similar in those infected with a phenotypically CA-MRSA strain compared to a phenotypically HA-MRSA strain (23% vs. 15%, P=0.10) as was 30-day mortality (16% vs. 19%, P=0.57). Independent risk factors associated with (P<0.05) treatment failure were higher Charlson Comorbidity Index, higher APACHE II score, and no anti-MRSA treatment. These factors were also associated with 30-day mortality, as were female gender, older age, MRSA bloodstream infection, MRSA pneumonia, and HIV. Our findings suggest that clinical and host factors, not MRSA strain type, predict treatment failure and death in hospitalized patients with MRSA-HAIs.

Inorganic zeolites are used for many practical applications that exploit the microporosity intrinsic to their crystal structures. Organic analogues, which are assembled from modular organic building blocks linked through non-covalent interactions, are of interest for similar applications. These range from catalysis, separation and sensor technology to optoelectronics, with enantioselective separation and catalysis being especially important for the chemical and pharmaceutical industries. The modular construction of these analogues allows flexible and rational design, as both the architecture and chemical functionality of the micropores can, in principle, be precisely controlled. Porous organic solids with large voids and high framework stability have been produced, and investigations into the range of accessible pore functionalities have been initiated. For example, catalytically active organic zeolite analogues are known, as are chiral metal-organic open-framework materials. However, the latter are only available as racemic mixtures, or lack the degree of framework stability or void space that is required for practical applications. Here we report the synthesis of a homochiral metal-organic porous material that allows the enantioselective inclusion of metal complexes in its pores and catalyses a transesterification reaction in an enantioselective manner. Our synthesis strategy, which uses enantiopure metal-organic clusters as secondary building blocks, should be readily applicable to chemically modified cluster components and thus provide access to a wide range of porous organic materials suitable for enantioselective separation and catalysis.