A scalable and catalyst-free method to deposit stoichiometric molybdenum disulfide (MoS2) films over large areas is reported, with the maximum area limited by the size of the substrate holder. The method allows deposition of MoS2 layers on a wide range of substrates without any additional surface preparation, including single-crystal (sapphire and quartz), polycrystalline (HfO2), and amorphous (SiO2) substrates. The films are deposited using carefully designed MoS2 targets fabricated with excess sulfur and variable MoS2 and sulfur particle size. Uniform and layered MoS2 films as thin as two monolayers, with an electrical resistivity of 1.54 × 10(4) Ω cm(-1), were achieved. The MoS2 stoichiometry was confirmed by high-resolution Rutherford backscattering spectrometry. With the method reported here, in situ graded MoS2 films ranging from ∼1 to 10 monolayers can be deposited.
The reinforcing effects of carbon nanotubes (CNTs) are investigated for aluminum matrix composites. The composites present a strong bonding between CNTs and the aluminum matrix using a controlled mechanical milling process, producing a network structure of aluminum atoms around CNTs. At the same time, CNTs that are dispersed during the milling process can be located inside aluminum powders, thereby providing an easy consolidation route via thermomechanical processes. A composite containing 4.5 vol% multiwalled CNTs exhibits a yield strength of 620 MPa and fracture toughness of 61 MPa·mm1/2, the values of which are nearly 15 and seven times higher than those of the corresponding starting aluminum, respectively.
A new type of wearable electronic device, called a textile memory, is reported. This is created by combining the unique properties of Al‐coated threads with a native layer of Al2O3 as a resistance switching layer, and carbon fiber as the counter‐electrode, which induces a fluent redox reaction at the interface under a small electrical bias (typically 2–3 V). These two materials can be embroidered into an existing cloth or woven into a novel cloth. The electrical resistance of the contacts is repeatedly switched by the bias polarity, as observed in the recently highlighted resistance switching memory. The devices with different structure from the solid metal‐insulator‐metal devices show reliable resistance switching behaviors in textile form by single stitch and in array as well that would render this new type of material system applicable to a broad range of emerging wearable devices. Such behavior cannot be achieved in other material choices, revealing the uniqueness of this material system.
A subgrid orographic parameterization (SOP) is updated by including the effects of orographic anisotropy and flow‐blocking drag (FBD). The impact of the updated SOP on short‐range forecasts is investigated using a global atmospheric forecast model applied to a heavy snowfall event over Korea on 4 January 2010. When the SOP is updated, the orographic drag in the lower troposphere noticeably increases owing to the additional FBD over mountainous regions. The enhanced drag directly weakens the excessive wind speed in the low troposphere and indirectly improves the temperature and mass fields over East Asia. In addition, the snowfall overestimation over Korea is improved by the reduced heat fluxes from the surface. The forecast improvements are robust regardless of the horizontal resolution of the model between T126 and T510. The parameterization is statistically evaluated based on the skill of the medium‐range forecasts for February 2014. For the medium‐range forecasts, the skill improvements of the wind speed and temperature in the low troposphere are observed globally and for East Asia while both positive and negative effects appear indirectly in the middle‐upper troposphere. The statistical skill for the precipitation is mostly improved due to the improvements in the synoptic fields. The improvements are also found for seasonal simulation throughout the troposphere and stratosphere during boreal winter.
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