When an artificial structure is built in a river, the river changes significantly in water quality and hydraulic properties. In this study, the effects of the weirs constructed in the middle section of a river as a four major rivers restoration project in Korea on water quality and hydrological characteristics were analyzed. For multi-dimensional data analysis, a self-organizing map was applied, and statistical techniques including analysis of variation were used.
View Article and Find Full Text PDFAstrocyte dysfunction and inflammation play a pivotal role in depression. In this study, we evaluated the antidepressant properties of root extract (HME), which is traditionally used for inflammation-related diseases, in a mouse model with astrocyte depletion that resembles the prefrontal cortex pathology of depressive patients. Mice were divided into four groups, with 10 mice per group.
View Article and Find Full Text PDFIn base-station-based underwater wireless acoustic networks (B-UWANs), effective handover mechanisms are necessary to ensure seamless data services for mobile nodes such as autonomous underwater vehicles (AUVs). Unlike terrestrial base stations (BSs), moored buoy BSs in B-UWANs experience motion responses due to wave loads under environmental conditions, posing unique challenges to the handover process. This study examines how BS motion affects handover decision errors, which arise when AUVs incorrectly initiate handovers to unintended BSs due to BS motion.
View Article and Find Full Text PDFAn unprecedented silver-mediated intramolecular oxy-argentation of 3-amidoaryne precursors that quickly generates a heteroarylsilver species is developed. AgF acts as both a stoichiometric fluoride source and a reagent for the formation of a benzoxazolylsilver intermediate via aryne generation. Pd-catalyzed coupling reactions of (hetero)aryl iodides with a silver species, generated in situ, allow for the synthesis of various C7-arylated benzoxazoles.
View Article and Find Full Text PDFNonpyrophoric aminophosphines reacted with indium(III) halides in the presence of zinc chloride have emerged as promising phosphorus precursors in the synthesis of colloidal indium phosphide (InP) quantum dots (QDs). Nonetheless, due to the required P/In ratio of 4:1, it remains challenging to prepare large-sized (>5 nm), near-infrared absorbing/emitting InP QDs using this synthetic scheme. Furthermore, the addition of zinc chloride leads to structural disorder and the formation of shallow trap states inducing spectral broadening.
View Article and Find Full Text PDFThe continuous flow synthesis of -sulfonyl-1,2,3-triazoles, which are convenient reactive azavinyl carbene precursors, for tandem relay Cu/Rh dual catalysis has been developed. Most reactions readily proceeded at 75 °C in a short residence time of 13.09 min in the presence of 2.
View Article and Find Full Text PDFThe adoption of low-crested and submerged structures (LCS) reduces the wave behind a structure, depending on the changes in the freeboard, and induces stable waves in the offshore. We aimed to estimate the wave transmission coefficient behind LCS structures to determine the feasible characteristics of wave mitigation. In addition, various empirical formulas based on regression analysis were proposed to quantitatively predict wave attenuation characteristics for field applications.
View Article and Find Full Text PDFEnvironmentally sustainable fuel cells with high efficiency have attracted much attention as a promising approach to resolving future energy problems. However, some obstacles must be overcome, such as corrosion, water control, and long-term degradation. Herein, we investigated the improved electrochemical performance and hydrogen oxidation reaction (HOR) mechanism of platinum loaded on carbon nanotube (Pt/CNT) catalyst by conducting experimental and theoretical studies.
View Article and Find Full Text PDFMagic-sized clusters (MSCs) can be isolated as intermediates in quantum dot (QD) synthesis, and they provide pivotal clues in understanding QD growth mechanisms. We report syntheses for two families of heterogeneous-atom-incorporated InP MSCs that have chlorine or zinc atoms. All the MSCs could be directly synthesized from conventional molecular precursors.
View Article and Find Full Text PDFIn this study, we designed and synthesized far-red- and near-infrared-emitting Cu-doped InP-based quantum dots (QDs), and we also demonstrated their highly specific and sensitive biological imaging ability. Cu-doped InP/ZnS (core/shell) QDs were prepared using the hot colloidal synthesis method in the organic phase. The ZnS shell passivates the surface and improves the photoluminescence (PL) intensity.
View Article and Find Full Text PDFAn efficient method was developed for the synthesis of unsymmetrical -arylsulfamides using sulfamoyl azides and arylboronic acids in the presence of 10 mol% of copper chloride as the catalyst. The reaction was facilitated in MeOH in an open flask at room temperature. Unlike the coupling of sulfamides and boronic acids, the use of sulfamoyl azides was found to be beneficial with respect to the yield and reaction time.
View Article and Find Full Text PDFPlatinum-based metal alloys have been generally developed to provide high carbon monoxide resistance in the anodes of direct methanol fuel cells. We report the potential of bimetallic platinum/iridium electrocatalysts in preserving the outstanding carbon monoxide tolerance obtained from both experimental and theoretical studies, which represents the enhanced electrochemical performance of methanol oxidation and the in-depth and stepwise investigations for reaction mechanisms, respectively. In this study, the findings highlight the dual-enhancement characteristics of low carbon monoxide adsorption energy (electronic effect) and carbon monoxide oxidative removal (bifunctional effect) compared with various electrocatalysts such as platinum, iridium, and platinum/ruthenium alloys.
View Article and Find Full Text PDFMn(III)-iodosylarene porphyrin adducts, [Mn(III)(ArIO)(Porp)], were synthesized by reacting electron-deficient Mn(III) porphyrin complexes with iodosylarene (ArIO) at -60 °C and characterized using various spectroscopic methods. The [Mn(III)(ArIO)(Porp)] species were then investigated in the epoxidation of olefins under stoichiometric conditions. In the epoxidation of olefins by the Mn(III)-iodosylarene porphyrin species, epoxide was formed as the sole product with high chemoselectivities and stereoselectivities.
View Article and Find Full Text PDF3-Hydroxy-2-(trialkylsilyl)phenyl triflates are presented as new versatile hydroxyaryne precursors. These are base-activated aryne precursors induced via a C-sp-to-O 1,3-Brook rearrangement. The reaction of various arynophiles and 3-trialkylsiloxybenzyne generated from 3-hydroxy-2-(trialkylsilyl)phenyl triflate efficiently afforded highly regioselective phenol derivatives.
View Article and Find Full Text PDFThree inorganic capping ligands (ICLs) for quantum dots (QDs), SnS4(4-), SbS4(3-) and AsS3(3-), were synthesized and the energy levels determined. Proximity between the ICL LUMO and QD conduction level governed the electronic couplings such as absorption shift upon ligand exchange, and electron transfer rate to TiO2. QD-sensitized solar cells were fabricated, using the ICL-QDs and also using QD multilayers layer-by-layer assembled by bridging coordinations, and studied as a function of the ICL ligand and the number of QD layers.
View Article and Find Full Text PDFThe prevalence of overweight in children has been dramatically increasing worldwide, and socioeconomic status is an important risk factor. The purpose of this study was to examine the hypothesis that household income is negatively associated with overweight in Korean and American girls and boys. In the study, 2117 children 7 to 12 years of age from the Korean National Health and Nutrition Examination Survey between 2001 and 2007 and 3016 children from the US National Health and Nutrition Examination Survey between 2001 and 2006 were included.
View Article and Find Full Text PDFThe purpose of this study was to examine the hypothesis that erythrocytes that are low in n-3 fatty acids and high in trans-fatty acids and nutrient intakes are associated with the risk of atherosclerosis. Fifty patients with acute nonfatal myocardial infarction were recruited to measure their dietary intake, erythrocyte fatty acid composition, intima medial thickness (IMT), and the Gensini score, which are markers of atherosclerosis. Trans-oleic acid of erythrocytes was positively (P = .
View Article and Find Full Text PDFThe aim of the present study is to investigate the learning-related changes in brain activation induced by the training of hypothesis generation skills regarding biological phenomena. Eighteen undergraduate participants were scanned twice with functional magnetic resonance imaging (fMRI) before and after training over a period of 2 months. The experimental group underwent eight biological hypothesis generation training programs, but the control group was not given any during the 2-month period.
View Article and Find Full Text PDFHypothesis generation has been regarded as one of the core reasoning processes in creative thinking and scientific discovery. To investigate changes in the amount of information transmission during scientific hypothesis generation, the averaged cross-mutual-information (A-CMI) of EEGs was estimated. Twenty-five 5th grade students were sampled in this study.
View Article and Find Full Text PDFThe purpose of the present study was to investigate differences in neural information transmission between gifted and normal children involved in scientific hypothesis generation. To investigate changes in the amount of information transmission, the children's averaged-cross mutual information (A-CMI) of EEGs was estimated during their generation of scientific hypotheses. We recorded EEG from 25 gifted and 25 age-matched normal children using 16 electrodes on each subject's scalp.
View Article and Find Full Text PDF