Enhanced terahertz conductivity in ultra-thin gold film deposited onto (3-mercaptopropyl) trimethoxysilane (MPTMS)-coated Si substrates

Various material properties change considerably when material is thinned down to nanometer thicknesses. Accordingly, researchers have been trying to obtain homogeneous thin films with nanometer thickness but depositing homogeneous few nanometers thick gold film is challenging as it tends to form islands rather than homogenous film. Recently, studies have revealed that treating the substrate with an organic buffer, (3-mercaptopropyl) trimethoxysilane (MPTMS) enables deposition of ultra-thin gold film having thickness as low as 5 nm. Different aspects of MPTMS treatment for ultrathin gold films like its effect on the structure and optical properties at visible wavelengths have been investigated. However, the effect of the MPTMS treatment on electrical conductivity of ultra-thin gold film at terahertz frequency remains unexplored. Here, we measure the complex conductivity of nanometer-thick gold films deposited onto an MPTMS-coated silicon substrate using terahertz time-domain spectroscopy. Following the MPTMS treatment of the substrate, the conductivity of the films was found to increase compared to those deposited onto uncoated substrate for gold films having the thickness less than 11 nm. We observed 5-fold enhancement in the conductivity for a 7 nm-thick gold film. We also demonstrate the fabrication of nanoslot-antenna arrays in 8.2-nm-thick gold films. The nanoslot-antenna with MPTMS coating has resonance at around 0.5 THz with an electric field enhancement of 44, whereas the nanoslot-antenna without MPTMS coating does not show resonant properties. Our results demonstrate that gold films deposited onto MPTMS-coated silicon substrates are promising advanced materials for fabricating ultra-thin terahertz plasmonic devices

Broadband high-performance terahertz polarizer based on a dense array of 5 nm gap slit antennas

Critical factors for terahertz polarizers include broadband operation, high transmittance, and a good extinction ratio. In this paper, using a 5 nm-wide metallic slit array with a 200 nm periodicity as a wire grid polarizer, we achieved over 95% transmittance with an average extinction ratio of 40 dB, over the entire spectrum as defined by the terahertz time-domain spectroscopy (0.4 - 2 THz). Theoretical calculations revealed that the slit array can show 100% transmission up to 5 THz, and wider bandwidths with a higher cutoff frequency can be achieved by reducing the slit periodicity. These results provide a novel approach for achieving a broadband THz polarizer and open a new path for seamless integration of the polarizers with nanophotonic applications. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreemen

Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit

Electromagnetic absorbers based on ultra-thin metallic film are desirable for many applications such as plasmonics, metamaterials, and long-wavelength detectors. A metallic film will achieve a maximum 50% of electromagnetic wave absorption, frequency independent, at a thickness defined by its conductivity, typically in the sub-Angstrom range for good metals if bulk conductivity is maintained throughout. This makes it extremely difficult to obtain substantial absorption from thin metal films, in contrast to 2D materials such as graphene. Luckily, however, from a practical point of view, metal conductivity is drastically reduced as the film becomes sub-100 nm, to make it a race between the thinnest possible metal thickness experimentally achievable vs the conductivity reduction. Here, we demonstrate a near-50% absorption at a gold film thickness of 6.5 nm, with conductivity much reduced from the bulk value, down to the range of 10(6) Siemens per meter. Studying the effect of the substrate thickness, we found that the common cover glass, with its thickness much smaller than the wavelength, achieves symmetric absorption of 44%, implying that a pseudo-free-standing limit is achieved. Our work may find applications in infrared sensing as in bolometers and biomedical sensing using microwaves

Ultra-Narrow Metallic Nano-Trenches Realized by Wet Etching and Critical Point Drying

A metallic nano-trench is a unique optical structure capable of ultrasensitive detection of molecules, active modulation as well as potential electrochemical applications. Recently, wet-etching the dielectrics of metal-insulator-metal structures has emerged as a reliable method of creating optically active metallic nano-trenches with a gap width of 10 nm or less, opening a new venue for studying the dynamics of nanoconfined molecules. Yet, the high surface tension of water in the process of drying leaves the nano-trenches vulnerable to collapsing, limiting the achievable width to no less than 5 nm. In this work, we overcome the technical limit and realize metallic nano-trenches with widths as small as 1.5 nm. The critical point drying technique significantly alleviates the stress applied to the gap in the drying process, keeping the ultra-narrow gap from collapsing. Terahertz spectroscopy of the trenches clearly reveals the signature of successful wet etching of the dielectrics without apparent damage to the gap. We expect that our work will enable various optical and electrochemical studies at a few-molecules-thick level

The pioneer round of translation ensures proper targeting of ER and mitochondrial proteins

The pioneer (or first) round of translation of newly synthesized mRNAs is largely mediated by a nuclear cap-binding complex (CBC). In a transcriptome-wide analysis of polysome-associated and CBC-bound transcripts, we identify RN7SL1, a noncoding RNA component of a signal recognition particle (SRP), as an interaction partner of the CBC. The direct CBC???SRP interaction safeguards against abnormal expression of polypeptides from a ribosome???nascent chain complex (RNC)???SRP complex until the latter is properly delivered to the endoplasmic reticulum. Failure of this surveillance causes abnormal expression of misfolded proteins at inappropriate intracellular locations, leading to a cytosolic stress response. This surveillance pathway also blocks protein synthesis through RNC???SRP misassembled on an mRNA encoding a mitochondrial protein. Thus, our results reveal a surveillance pathway in which pioneer translation ensures proper targeting of endoplasmic reticulum and mitochondrial proteins

The impact of two-dimensional versus three-dimensional art therapy on locus of control in special needs children in South Korea

Children with special needs often have a tendency to be externally oriented because of their accumulated failure experiences. Accordingly, when children enjoy successful experiences through art making, they may be more likely to feel a sense of control and employ their own abilities The purpose of this study was to identify differences in the impact of two-dimensional (2D) versus three-dimensional (3D) art materials on LOC in South Korean elementary school children with special needs. This study compares the effects of 2D and 3D clay-based art materials in art therapy on LOC in special needs children in group art therapy in South Korea. This mixed methods study employed a quantitative pre and post-test control group design with a qualitative component. 15 Children with special needs in a South Korean elementary school were divided into three groups using: (1) 2D art media only, (2) only 3D clay-based art media only, and (3) no artistic intervention. The two treatment groups underwent 10 sessions of art therapy. The age of the15 participants ranged from 7-12 years. The Stanford Preschool Internal-External Scale (Mischel, Zeiss, and Zeiss, 1974) was utilized for both the pre- and posttests. For qualitative data, observation, teacher interview, and art pieces were used. One-way ANOVA, Shapiro-Wilk Statistic, post hoc test (Student-Newman-Keuls, Duncan, and Keuky HSD test), paired samples test, and Wilcoxon singed rank test were used for quantitative analysis. Result of quantitative and qualitative data indicate that 2D group and 3D group both showed increased internal LOC score, however, 3D group showed more significant change when analyzed the data using Post-hoc test (SNK and Duncan). The result supported the use of clay-based 3D art media aimed special needs children group art therapy programs

Branding Korea though collaborative strategies with the Olympic movement

노트 : Master exécutif en management des organisations sportives, MEMOS XIV (2010-2011

Why do(n't) young people watch the Olympics?: A comparison of motives and constraints for attendance and media viewing

This study investigates internal and external motives, and intrapersonal, interpersonal, and structural constraints affecting domestic young peoples intentions for attending or media viewing the 2018 PyeongChang Winter Olympics. Through thought-listing, key motives and constraints are identified. Based on surveys and SEM analysis, relationships among motives, constraints, and intentions are tested, and findings related to attendance and media viewing are compared. Perceived motives/constraints/intentions in host and non-host regions are compared based on mean structure analysis. Universal (e.g., curiosity, enjoyment, social influence) and contextual (e.g., lack of knowledge, cost) motives/constraints affecting attendance and/or media viewing are identified. Interestingly, only structural constraints affect attendance intention, whereas intra- and interpersonal constraints affect media viewing intention as well. Perceived levels of motives/constraints/intentions partially vary between host and non-host regions. Diversified marketing strategies for Olympics attendance and media viewing in host- and non-host regions are discussed. Copyright © 2021 Inderscience Enterprises Ltd.N

Can Esports Substitute Traditional Sports? The Convergence of Sports and Video Gaming during the Pandemic and Beyond

This research examines the various ways that video games, particularly esports, have been leveraged for content production and fan engagement (i.e., gamification) in traditional sports during the COVID-19 pandemic, as well as sports fans’ reactions in relation to their motives, points of attachment, and other consumer behavior. The study presents a sports–gaming convergence framework and identifies six popular gamification modes where video games and traditional sports converge during the pandemic. The survey results further reveal that gamification content is not consumed as simply a “substitute” for traditional sports, but instead a complementary yet unique product. In conclusion, we suggest that it is critical to recognize the differences between fans of video games and fans of traditional sports concerning market segmentation. Nevertheless, esports could effectively bridge these two industries and their consumers by enriching the content offering and extending distribution channels