Thermal Conductivity and Thermal Boundary Resistances of ALD Al$$_{}$$O$$_{3}$$3 Films on Si and Sapphire

On Si and sapphire substrates, 6–45 nm thick films of atomic layer-deposited Al\(_{2}\)O\(_{3}\) were grown. The thermal conductivity of ALD films has been determined from a linear relation between film thickness and thermal resistance measured by the 3\(\omega \) method. ALD films on Si and sapphire showed almost same thermal conductivity in the temperature range of 50–350 K. Residual thermal resistance was also obtained by extrapolation of the linear fit and was modeled as a sum of the thermal boundary resistances at heater–film and film–substrate interfaces. The total thermal resistance addenda for films on sapphire was close to independently measured thermal boundary resistance of heater–sapphire interface. From the result, it was deduced that the thermal boundary resistance at ALD Al\(_{2}\)O\(_{3}\)–sapphire interface was much lower than that of heater–film. By contrast, the films on Si showed significantly larger thermal boundary resistance than films on sapphire. Data of \(< 30\) nm films on Si were excluded because an AC coupling of electrical heating voltage to semiconductive Si complicated the relation between 3\(\omega \) voltage and temperature.     

Flexible Hard Coating: Glass‐Like Wear Resistant,Yet Plastic‐Like Compliant,Transparent Protective Coating for Foldable Displays

A flexible hard coating for foldable displays is realized by the highly cross‐linked siloxane hybrid using structure–property relationships in organic–inorganic hybridization. Glass‐like wear resistance, plastic‐like flexibility, and highly elastic resilience are demonstrated together with outstanding optical transparency. It provides a framework for the application of siloxane hybrids in protective hard coatings with high scratch resistance and flexibility for foldable displays.     

Interface Control of Ferroelectricity in an SrRuO3/BaTiO3/SrRuO3 Capacitor and its Critical Thickness

The atomic‐scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure during growth plays an important role in controlling the interfacial terminations of SrRuO₃/BaTiO₃/SrRuO₃ (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high (around 150 mTorr), usually exhibits a mixture of RuO₂–BaO and SrO–TiO₂ terminations. By reducing , the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO–TiO₂ termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells.     

Fabrication of Millimeter‐Long Carbon Tubular Nanostructures Using the Self‐Rolling Process Inherent in Elastic Protein Layers

Millimeter‐long conducting fibers can be fabricated from carbon nanomaterials via a simple method involving the release of a prestrained protein layer. This study shows how a self‐rolling process initiated by polymerization of a micropatterned layer of fibronectin (FN) results in the production of carbon nanomaterial‐based microtubular fibers. The process begins with deposition of carbon nanotube (CNT) or graphene oxide (GO) particles on the FN layer. Before polymerization, particles are discrete and nonconducting, but after polymerization the carbon materials become entangled to form an interconnected conducting network clad by FN. Selective removal of FN using high‐temperature combustion yields freestanding CNT or reduced GO microtubular fibers. The properties of these fibers are characterized using atomic force microscopy and Raman spectroscopy. The data suggest that this method may provide a ready route to rapid design and fabrication of aligned biohybrid nanomaterials potentially useful for future electronic applications.     

A Fluid Liquid‐Crystal Material with Highly Polar Order

An anomalously large dielectric permittivity of ≈10⁴ is found in the mesophase temperature range (MP phase) wherein high fluidity is observed for a liquid‐crystal compound having a 1,3‐dioxane unit in the mesogenic core (DIO). In this temperature range, no sharp X‐ray diffraction peak is observed at both small and wide Bragg angles, similar to that for a nematic phase; however, an inhomogeneous sandy texture or broken Schlieren one is observed via polarizing optical microscopy, unlike that for a conventional nematic phase. DIO exhibits polarization switching with a large polarization value, i.e., P = 4.4 µC cm^?2, and a parallelogram‐shaped polarization–electric field hysteresis loop in the MP phase. The inhomogeneously aligned DIO in the absence of an electric field adopts a uniform orientation along an applied electric field when field‐induced polarization switching occurs. Furthermore, sufficiently larger second‐harmonic generation is observed for DIO in the MP phase. Second‐harmonic‐generation interferometry clearly shows that the sense of polarization is inverted when the +/? sign of the applied electric field in MP is reversed. These results suggest that a unidirectional, ferroelectric‐like parallel polar arrangement of the molecules is generated along the director in the MP phase.     

Spatial arrangement using deep reinforcement learning to minimise rearrangement in ship block stockyards

As the shipbuilding industry is an engineering-to-order industry, different types of products are manufactured according to customer requests, and each product goes through different processes and workshops. During the shipbuilding process, if the product is not able to go directly to the subsequent process due to physical constraints of workshop, it temporarily waits in a stockyard. Since the waiting process involves unpredictable circumstances, plans regarding time and space cannot be established in advance. Therefore, unnecessary movement often occurs when ship blocks enter or depart from the stockyard. In this study, a reinforcement learning approach was proposed to minimise rearrangement in such circumstances. For this purpose, an environment in which blocks are arranged and rearranged was defined. Rewards based on the simplified rules were logically defined, and simulation was performed for quantitative evaluation using the proposed reinforcement learning algorithm. This algorithm was verified using an example model derived from actual data from a shipyard. The method proposed in this study can be used not only to the arrangement problem of ship block stockyards but also to the various arrangement and allocation problems or logistics problems in the manufacturing industry.