Photonic Crystal Palette of Binary Block Copolymer Blends for Full Visible Structural Color Encryption

Structural color (SC) arising from a periodically ordered self-assembled block copolymer (BCP) photonic crystal (PC) is useful for reflective-mode sensing displays owing to its capability of stimuli-responsive structure alteration. However, a set of PC inks, each providing a precisely addressable SC in the full visible range, has rarely been demonstrated. Here, a strategy for developing BCP PC inks with tunable structures is presented. This involves solution-blending of two lamellar-forming BCPs with different molecular weights. By controlling the mixing ratio of the two BCPs, a thin 1D BCP PC film is developed with alternating in-plane lamellae whose periodicity varies linearly from ≈46 to ≈91 nm. Subsequent preferential swelling of one-type lamellae with either solvent or non-volatile ionic liquid causes the photonic band gap of the films to red-shift, giving rise to full-visible-range SC correlated with the pristine nanostructures of the blended films in both liquid and solid states. The BCP PC palette of solution-blended binary solutions is conveniently employed in various coating processes, allowing facile development of BCP SC on the targeted surface. Furthermore, full-color SC paintings are realized with their transparent PC inks, facilitating low-power pattern encryption.     

Modus Operandi of Simultaneous Covering Synthesis from Precursor Heterogeneity for Shelled Nanorods for Multipotent Cancer Theranostics

The synthesis of nanostructures using homogeneous precursors in the solution phase is widely used to achieve uniformity and well‐defined morphological control. However, drawbacks such as the lack of diversity due to the limited reaction rate modulation exist. One‐step, core–shell nanorod formation using simultaneous covering synthesis using solid and ionic heterogeneous precursors is proposed in this study. A Te‐Bi₂Te₃/TeO₂ core–shell structure is successfully synthesized by precisely controlling various influencing factors, including concentration, temperature, and pH, and its physicochemical and photochemical properties are thoroughly investigated. The proposed nanostructure overcomes the oxidation susceptibility of Te and can be applied to multipotent cancer theranostics in vitro and in vivo in combination with computed tomography imaging.     

High‐Precision Temperature‐Controllable Metal‐Coated Polymeric Molds for Programmable,Hierarchical Patterning

Nanofabrication is an indispensable process in nanoscience and nanotechnology. Unconventional lithographic techniques are often used for fabrication as alternatives to photolithography because they are faster, more cost‐effective, and simpler to use. However, these techniques are limited in scalability and utility because of the collapse of preprinted structures during step‐and‐repeat processes. This study proposes a new class of temperature‐controllable polymeric molds that are coated with a metal such that any site‐specific patterning can be accomplished in a programmable manner using selective contact‐dewetting lithography. The lithography allows sub‐100 nm patterning, step‐and‐repeat processing, and hierarchical structure fabrication. The programmable feature of the lithography can be utilized for the structural coloring and shaping of objects. Large‐area programmable patterning, semiconductor device manufacturing, and the fabrication of iridescent security devices would benefit from the unique features of the proposed strategy.     

Protection of Digital TV from Cognitive Radio Interference

Analytic modeling and computational simulation for the protection of DTV from cognitive radio interference are performed. Protection is achieved by using the protection ratio, which is derived through system modeling and its analysis. On the frequency coordination between digital TV and cognitive radio, an analysis in a co‐channel environment, in a rural area in Korea, is performed.     

Stable single-frequency fiber ring laser for 25-GHz ITU-T grids utilizing saturable absorber filter

A stable single-frequency fiber ring laser is proposed that operates in a single mode for more than an hour by incorporating unpumped erbium-doped fiber (EDF) as a saturable absorber filter and optimizing the length of EDF used as gain medium. This laser can be continuously tuned to 25-GHz spacing that precisely matches the ITU-T grids by temperature control of etalon filter. This laser had a signal-to-source spontaneous emission ratio higher than 70 dB, and lasing frequencies of 361 channels was matched to ITU-T grids with excellent flatness. Frequency offset from the ITU-T grid was less than 0.14 GHz. The linewidth and the relative intensity noise value was less than 1.3 kHz and 130 dB/Hz (above 250 kHz), respectively.     

Use and Disuse of Contextual Primes in Dynamic News Environments

This study reexamines the news priming effects of the 1991 Persian Gulf War. Suggesting an alternative approach to those used in previous studies, this study assesses individuals' use and disuse of a contextual prime (i.e., the air war) in dynamic news environments. With a short-term, quasi-experimental approach considering the air war as a prime stimulus, a path analysis suggests robust evidence of the short-term accessibility effects of priming. More importantly, as suggested in Martin's (1986) set/reset model, this study extends priming effects beyond the simple hydraulic patterns of accessibility effects. It reveals that both attitudes toward military action and attitudes toward a diplomatic solution were used in subsequent judgments of the president's job performance and handling of the war. The associations between attitudes toward a diplomatic solution and subsequent judgments were even stronger than those between attitudes toward military action and the same subsequent judgments, despite the clear prowar primes of news discourse in the air-war context. This pattern was more greatly intensified among those in the high news attention group than those in the low news attention group     

Dynamic Response Modeling of MEMS Micromirror Corner Cube Reflectors With Angular Vertical Combdrives

A model for the dynamic response of microelectromechanical-systems micromirrors with angular vertical combdrive electrostatic actuators has been proposed based on a numerical solution of the nonlinear dynamic equations for torsional oscillation. The torque generated by the electrostatic drive is assumed to depend at least on the second order of the turn angle, and the model shows a shift in the resonant frequency with drive voltage, in agreement with the experimental results obtained from components fabricated by self-assembly of bonded silicon parts. The dynamic response of a corner cube reflector (CCR) based on a pair of scanning mirrors and a fixed mirror is predicted using the model, and the theoretical response agrees well with the experimental results. From the model, a small initial misalignment of the CCR mirrors can be determined     

Hydrophobic Chromophores in Aqueous Micellar Solution Showing Large Two‐Photon Absorption Cross Sections

A series of new hydrophobic two‐photon absorbing (2PA) chromophores with varied electron‐donating groups in quasi‐linear and multibranched structures are synthesized to correlate their structure/photophysical property relationships. The feasibility of using these large two‐photon absorption cross‐sectional (δ, expressed in GM = 1 × 10^–50 cm⁴ s photon^–1 molecule^–1) materials in aqueous solution is also explored. All four hydrophobic 2PA materials can be encapsulated into micelles generated by dispersing an amphiphilic block copolymer, poly(methacrylic acid)‐block‐polystyrene (PMAA‐b‐PS), into water. The micellar nanostructures are characterized using dynamic light scattering, atomic force microscopy, and transmission electron microscopy. After these dyes are incorporated into micelles, they exhibit strong fluorescence in water. It is found that the quantum yield and δ values of these chromophores are strongly dependent on the diameters of the micelles, concentrations of the PMAA‐b‐PS, and molecular structures of the 2PA chromophores. One of the compounds that has a strong triarylamino donor and a multibranched structure exhibits a large δ value of 2790 GM and high quantum yield (0.56) in micelle‐containing water. Although this value is smaller than the original value of 5300 GM in toluene, it is still substantially larger than the values of most water‐soluble 2PA materials, which have δ values of less than 100 GM.     

A Multi‐Strategic Concept‐Spotting Approach for Robust Understanding of Spoken Korean

We propose a multi‐strategic concept‐spotting approach for robust spoken language understanding of conversational Korean in a hostile recognition environment such as in‐car navigation and telebanking services. Our concept‐spotting method adopts a partial semantic understanding strategy within a given specific domain since the method tries to directly extract pre‐defined meaning representation slot values from spoken language inputs. In spite of partial understanding, we can efficiently acquire the necessary information to compose interesting applications because the meaning representation slots are properly designed for specific domain‐oriented understanding tasks. We also propose a multi‐strategic method based on this concept‐spotting approach such as a voting method. We present experiments conducted to verify the feasibility of these methods using a variety of spoken Korean data.     

Mergers and Acquisitions in the Telecommunications Industry: Myths and Reality

This paper investigates how market participants react to mergers and acquisitions (M&As) involving telecommunications companies. The empirical evidence suggests that such activities convey bad news to the market. This is consistent with the synergy trap hypothesis and extant empirical findings of value‐reducing diversification strategies in recent literature. The evidence also indicates that a cross‐border, rather than a domestic M&A deal, is the main driver of the negative market reaction. Further, our evidence of negative impacts on the bidder's business after an M&A reinforces our main finding that market participants, on average, perceive M&A activities to be detrimental to shareholder value. This suggests that value creation or synergy through an M&A deal is not warranted even though it can generate an increase in size of the firm.