improved-polydimethylsiloxane-pdms-double-casting-via-silicone-oil

Improved Polydimethylsiloxane (PDMS) Double Casting via Silicone Oil Treatment for Densely Packed Microstructure Replication

Polydimethylsiloxane (PDMS) double casting is widely used for replicating microscale structures, including microfluidic channels and biomedical ...

Gwangju Institute of Science and Technology

We will discuss fabrication of twin core photonic crystal fiber (TC-PCF) using the stack-and-draw method and its application for in-line Mach-Zehnder interferometers. The small difference in the effective indexes of the two core modes leads to interference fringes and the birefringence of the twin cores results in polarization-dependent fringe spacing. The strain sensitivity was negative and wavelength-dependent. A novel intensity-based bend sensor is also demonstrated with bend-induced spatial fringe shift. High air filling fraction of fabricated TC-PCF cladding provides immunity to bend-induced intensity fluctuation.

Twin core photonic crystal fiber for in-line Mach-Zehnder interferometric sensing applications.

To assess the basal resources supporting food webs impacted by rainfalls, we compared stable isotope ratios (δC and δN) of fish consumers and organic matter sources between up- and down-sites in an estuary between seasons (June and September) and years (2018 and 2019) that showed different patterns of summer monsoon. Our study showed seasonal differences in the δC and δN values of basal resources and fish consumers in both years. At the up-site, significant differences of δC values of fish consumers were found between years, resulting from changing rainfall period, thereby causing a shift in food availability from terrigenous organic matter to periphyton. In contrast, at the down-site, the consistent isotopic values of fishes were observed in both years, suggesting that rainfall shift has a negligible impact on resources for fishes. Overall, the annual shift in resources for fishes in the estuary may be controlled by contrasting rainfall events.

Trophic response of fishes to rainfall variability in a temperate estuarine system of Korea: A stable isotope approach.

Copper-tantalate, CuTaO (CTO), shows significant promise as an efficient photocathode for multi-carbon compounds (C) production through photoelectrochemical (PEC) CO reduction, owing to its suitable energy bands and catalytic surface. However, synthesizing CTO poses a significant challenge due to its metastable nature and thermal instability. In this study, this challenge is addressed by employing a flux-mediated synthesis technique using a sodium-based flux to create sodium-doped CTO (Na-CTO) thin films, providing enhanced nucleation and stabilization for the CTO phase. To evaluate the PEC performance and catalytic properties of the films, copper(II) oxide (CuO) at the Na-CTO surface is selectively etched. The etched Na-CTO shows a lower dark current, with decreased contribution from photocorrosion, unlike the non-etched Na-CTO which has remaining CuO on the surface. Furthermore, Na-CTO exhibits 7.3-fold ethylene selectivity over hydrogen, thus highlighting its promising potential as a photocathode for C production through PEC CO reduction.

Copper Tantalate by a Sodium-Driven Flux-Mediated Synthesis for Photoelectrochemical CO Reduction.

Two-dimensional SnSe (X = 1, 2) has emerged as a promising candidate for a NO chemiresistive sensor due to a remarkable affinity to NO gas adsorption. Although their gas sensing mechanism primarily relies on direct charge transfer, the underlying mechanisms of SnSe and SnSe remain unclear, despite various reported successes in phase engineering of SnSe. Here, we investigate phase engineering of SnSe in a hydrothermal route via 1-dodecanethiol (1-DDT), which served as a phase stabilizer, and comprehensively demonstrate phase-dependent NO detection properties. As the 1-DDT concentration increases, we directly confirm that the SnSe structure was gradually transformed to the SnSe one. This transformation correlates with a gradual increase in NO gas responses from 45 to 1430%, the highest value reported among SnSe-based NO gas sensors. The obtained SnSe-based sensors also exhibit a good NO discrimination without configuration of sensor arrays, under an interfering gas atmosphere in humidity conditions. Our computational calculation also unveils that these outstanding detection performances are attributed to well-constructed SnSe coupled with a single Se vacancy to enhance a stronger NO adsorption than SnSe. Finally, we demonstrate a sensor module system based on SnSe, enabling real-time monitoring of NO gas.

Phase Engineering of SnSe (X = 1,2) Microstructures for High-Performance NO Chemiresistive Room-Temperature Sensor Systems: Toward Highly Reliable and Robust Detection Properties under Humidity and Interfering Gas Conditions.

The river transports dissolved and particulate matter to the estuary, where physical and biogeochemical transitions occur. In the river-estuary transition zone (RETZ), phytoplankton response is an effective indicator of environmental variability with their immediate responses. Here, we examine summer-monsoonal variability in productivity and nitrogen uptake of phytoplankton in three major Korean rivers and their estuaries: the Han, Geum, and Yeongsan. Results showed that summer-monsoonal variability of primary productivity in dam-constructed RETZ divided them into riverine zone governed by nutrient-phytoplankton interactions and estuarine zone associated with nitrogenous substrate dynamics. In contrast, free-flowing RETZ exhibited lower variability in phytoplankton productivity due to simultaneously enhanced nitrogenous nutrients and turbidity. Our generalized additive model analysis indicated that composition of particulate organic matter is primarily correlated with phytoplankton biomass associated with light availability. Our findings emphasize the complex interplay of physical and biogeochemical processes in RETZ, mainly influenced by monsoonal variability and river-estuary connectivity.

Article	Year
Twin core photonic crystal fiber for in-line Mach-Zehnder interferometric sensing applications. Optics express\| PubMed ID: 19724547	2009
Trophic response of fishes to rainfall variability in a temperate estuarine system of Korea: A stable isotope approach. Marine pollution bulletin\| PubMed ID: 37369155	2023
Copper Tantalate by a Sodium-Driven Flux-Mediated Synthesis for Photoelectrochemical CO Reduction. Small methods\| PubMed ID: 39815160	2025
Phase Engineering of SnSe (X = 1,2) Microstructures for High-Performance NO Chemiresistive Room-Temperature Sensor Systems: Toward Highly Reliable and Robust Detection Properties under Humid... ACS sensors\| PubMed ID: 39818782	2025
Dual effects of estuarine dams on summertime phytoplankton productivity in temperate river-estuary transition zones. Marine environmental research\| PubMed ID: 40466499	2025

Taehoon Kim

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