Identifying and Verifying Vulnerabilities through PLC Network Protocol and Memory Structure Analysis

Cyberattacks on the Industrial Control System (ICS) have recently been increasing, made more intelligent by advancing technologies. As such, cybersecurity for such systems is attracting attention. As a core element of control devices, the Programmable Logic Controller (PLC) in an ICS carries out on-site control over the ICS. A cyberattack on the PLC will cause damages on the overall ICS, with Stuxnet and Duqu as the most representative cases. Thus, cybersecurity for PLCs is considered essential, and many researchers carry out a variety of analyses on the vulnerabilities of PLCs as part of preemptive efforts against attacks. In this study, a vulnerability analysis was conducted on the XGB PLC. Security vulnerabilities were identified by analyzing the network protocols and memory structure of PLCs and were utilized to launch replay attack, memory modulation attack, and FTP/Web service account theft for the verification of the results. Based on the results, the attacks were proven to be able to cause the PLC to malfunction and disable it, and the identified vulnerabilities were defined.     

Anionic Redox Chemistry as a Clue for Understanding the Structural Behavior in Layered Cathode Materials

The anionic redox chemistries of layered cathode materials have been in focus recently due to an intriguing phenomenon that cannot be described by the number of electrons of transition metal ions. However, even though several studies have investigated the anionic redox chemistry of layered materials in terms of the charge compensation, the relationship between the origin of the structural behavior and anionic redox chemistry in layered materials remains poorly understood. In addition, a simultaneous redox process of transition metal ions could occur through the d bands interaction. Here, it is demonstrated that the anionic redox chemistry is associated with the anisotropic structural behavior of the layered cathode materials albeit without providing additional capacities exceeding the theoretical values. These findings will provide a foundation of a new chapter in the understanding of the properties of materials.     

Template Engineering of CuBi2O4 Single‐Crystal Thin Film Photocathodes

To develop strategies for efficient photo‐electrochemical water‐splitting, it is important to understand the fundamental properties of oxide photoelectrodes by synthesizing and investigating their single‐crystal thin films. However, it is challenging to synthesize high‐quality single‐crystal thin films from copper‐based oxide photoelectrodes due to the occurrence of significant defects such as copper or oxygen vacancies and grains. Here, the CuBi₂O₄ (CBO) single‐crystal thin film photocathode is achieved using a NiO template layer grown on single‐crystal SrTiO₃ (STO) (001) substrate via pulsed laser deposition. The NiO template layer plays a role as a buffer layer of large lattice mismatch between CBO and STO (001) substrate through domain‐matching epitaxy, and forms a type‐II band alignment with CBO, which prohibits the transfer of photogenerated electrons toward bottom electrode. The photocurrent densities of the CBO single‐crystal thin film photocathode demonstrate ?0.4 and ?0.7 mA cm^?2 at even 0 V_RHE with no severe dark current under illumination in a 0.1 m potassium phosphate buffer solution without and with H₂O₂ as an electron scavenger, respectively. The successful synthesis of high‐quality CBO single‐crystal thin film would be a cornerstone for the in‐depth understanding of the fundamental properties of CBO toward efficient photo‐electrochemical water‐splitting.     

Imidazolium-Functionalized Diacetylene Amphiphiles: Strike a Lighter and Wear Polaroid Glasses to Decipher the Secret Code

The development of smart inks that change color and transparency in response to external stimuli is very important for various fields, from modern art to safety and anticounterfeiting technology. A uniaxially oriented diacetylene thin film on a macroscopic area is obtained by coating, self-assembling and topochemical photopolymerizing of imidazolium-functionalized diacetylenes (M-DA and T-DA) and 4,6-decadiyne ink (70 wt%:20 wt%:10 wt%) exhibiting a lyotropic smectic A liquid-crystalline phase at room temperature. The color and transparency of letters and symbols written with the DA-based secret inks change reversibly from blue to red as well as from colorless transparent to black opaque depending on the temperature and polarization axis. A secret code written with thermoresponsive and polarization-dependent secret inks consisting of imidazolium-functionalized diacetylenes is successfully deciphered by wearing polaroid glasses and holding a burning torch.     

Organic Light-Emitting Diodes: Pushing Toward the Limits and Beyond

Organic light-emitting diodes (OLEDs) are established as a mainstream light source for display applications and can now be found in a plethora of consumer electronic devices used daily. This success can be attributed to the rich luminescent properties of organic materials, but efficiency enhancement made over the last few decades has also played a significant role in making OLEDs a practically viable technology. This report summarizes the efforts made so far to improve the external quantum efficiency (EQE) of OLEDs and discusses what should further be done to push toward the ultimate efficiency that can be offered by OLEDs. The study indicates that EQE close to 58% and 80% can be within reach without and with additional light extraction structures, respectively, with an optimal combination of cavity engineering, low-index transport layers, and horizontal dipole orientation. In addition, recent endeavors to identify possible applications of OLEDs beyond displays are presented with emphasis on their potential in wearable healthcare, such as OLED-based pulse oximetry as well as phototherapeutic applications based on body-attachable flexible OLED patches. OLEDs with fabric-like form factors and washable encapsulation strategies are also introduced as technologies essential to the success of OLED-based wearable electronics.     

Microstructure and dielectric properties of compositionally graded Ba1-xSrxTiO3 multilayer tunable capacitors

Li₂O/B₂O₃-added Ba_1-xSr_xTiO₃ (B_1-xS_xT) ceramics, where 0.2 ≤ x ≤ 0.35, were well densified at 920 °C with pure perovskite structure. The dielectric constant, tunability, and figure of merit (FOM) of B_1-xS_xT ceramics increased with x because of the decreasing Curie temperature (T_C). The specimen with x = 0.35, whose T_C was close to room temperature, exhibited a large tunability of 27.4 % and FOM of 110 at 10 kV/cm. A compositionally graded multilayer (CGML), which was sintered at 920 °C, was fabricated using B_1-xS_xT thick films to produce a temperature-stable tunable capacitor, and it evinced a dense microstructure and a continuous interface between the B_1-xS_xT thick film and the Ag electrode. This CGML capacitor showed a large tunability (51 %) and FOM (150) at 20 kV/cm. It also exhibited stable tunability (17–28 % at 10 kV/cm) at temperatures between 30–90 °C. Therefore, the B_1-xS_xT CGML capacitor is a suitable candidate for temperature-stable tunable capacitors.     

Stabilization of 6H-Hexagonal SrMnO3 Polymorph by Al2O3 insertion

We demonstrate the structural evolution of polymorphic phases in Al₂O₃-inserted SrMnO₃ ceramics synthesized by solid state reaction. While the 4H-hexagonal phase is predominant in pure SrMnO₃ ceramics, a small amount of 6H-hexagonal polymorph is identified in addition to the primary 4H-hexagonal SrMnO₃ and the secondary hexagonal SrAl₂O₄ phases in the as-sintered ceramics, evidenced by x-ray diffraction and subsequent Rietveld refinement analyses. The existence of the 6H-hexagonal SrMnO₃ phase is corroborated using Raman spectroscopy. The chemical compositions and electronic structures of the Al₂O₃-inserted SrMnO₃ compounds are also examined using energy dispersive spectroscopy and x-ray photoelectron spectroscopy, respectively. The first-principles calculations reveal that there is no clear difference between the total energies of 4H- and 6H-hexagonal polymorphs regardless of the presence/absence of Sr and oxygen vacancies. Possible origins are discussed with the estimation of actual strain based on the refined lattice parameter of 6H SrMnO₃.