Azide-Alkyne Huisgen [3+2] Cycloaddition Using CuO Nanoparticles

Recent developments in the synthesis of CuO nanoparticles (NPs) and their application to the [3+2] cycloaddition of azides with terminal alkynes are reviewed. With respect to the importance of click chemistry, CuO hollow NPs, CuO hollow NPs on acetylene black, water-soluble double-hydrophilic block copolymer (DHBC) nanoreactors and ZnO-CuO hybrid NPs were synthesized. Non-conventional energy sources such as microwaves and ultrasound were also applied to these click reactions, and good catalytic activity with high regioselectivity was observed. CuO hollow NPs on acetylene black can be recycled nine times without any loss of activity, and water-soluble DHBC nanoreactors have been developed for an environmentally friendly process.open6

Associations between the Timing and Nutritional Characteristics of Bedtime Meals and Sleep Quality for Nurses after a Rotating Night Shift: A Cross-Sectional Analysis

The purpose of this study was to investigate the associations of the timing and nutritional characteristics of bedtime meals with sleep quality in nurses after rotating night shifts. In total, 128 nurses from a university hospital in South Korea participated in this cross-sectional study. Data were collected on the first night of two or three consecutive routine night shifts. Participants recorded all food eaten before going to bed after work. An accelerometer was used to objectively measure sleep quality, and subjective sleep quality was assessed by self-report using the Korean version of the Verran and Snyder-Halpern Sleep Scale. The associations of timing and nutritional characteristics of bedtime meals with sleep quality after night shifts were analyzed using multivariate linear regression. A short time interval between meals and sleep was associated with longer objectively measured total sleep time (β = −0.37, p = 0.002), and the proportion of protein in meals was associated with better objectively measured sleep efficiency (β = 0.31, p = 0.007). The shorter the time interval, the better the subjective sleep quality (β = −0.23, p = 0.048), and high-calorie meals were positively associated with subjective sleep quality (β = 0.23, p = 0.043). Based on our findings, we encourage nurses to have protein-rich meals after night shifts and reduce the delay between meals and sleep. Although high-calorie meals were shown to have a positive effect on subjective sleep quality, it is necessary to confirm this effect through additional research

Dopamine-assisted wet spinning and mechanical reinforcement of graphene oxide fibers

Bioinspired polydopamine coatings have been widely used for the surface modification of various materials because of their strong adhesion, facile application method, and functionalization ability. However, dopamine has not been previously utilized as a coagulation agent for graphene oxide fibers (GOFs). In this study, we performed the wet spinning of GOFs using dopamine as a coagulation agent (denoted as DA-GOFs) and successive polymerization of dopamine inside the fibers. The polymerized DA-GOFs (pDA-GOFs) exhibited enhanced mechanical properties with a 97% higher tensile strength than that of the fibers coagulated with CaCl2. The described dopamine-assisted wet spinning and polymerization process were simple but effective method for preparing mechanically strong fibers, which can be potentially employed in flexible and wearable electronic applications

Photocatalytic dehydrogenation of organic hydrogen carrier on Pd-TiO2(110) surfaces

Hydrogen can be stored in a liquid organic hydrogen carrier (LOHC) via the formation of chemical bonds with carbon. Most recently studied LOHC molecules store hydrogen through the transformation between cyclohexane and benzene. However, because the C???H bonds of cyclohexane are difficult to break, catalysts and high temperatures are usually required to achieve this transformation. In this study, we investigated the photocatalytic dehydrogenation of cis-1,4-diaminocyclohexane on the surface of TiO2(110) decorated with Pd nanoparticles by low-temperature scanning tunnelling microscopy and X-ray photoelectron spectroscopy. The photocatalytic dissociation of the C???H bond was observed on Pd-decorated TiO2 but not on the bare TiO2 surface under 365 nm UV irradiation. We showed that the dehydrogenation reaction is induced by hot electrons produced by the dielectric response of TiO2(110) toward plasmonic metal nanoparticles. The photocatalytic dehydrogenation is performed under extremely low temperature and pressure compared to conventional dehydrogenation processes of LOHC molecules, which suggests a prospective pathway of the H2-release process for the LOHCs

Uniform Pressing Mechanism in Large-Area Roll-to-Roll Nanoimprint Lithography Process

We aimed to increase the processing area of the roll-to-roll (R2R) nanoimprint lithography (NIL) process for high productivity, using a long roller. It is common for a long roller to have bending deformation, geometric errors and misalignment. This causes the non-uniformity of contact pressure between the rollers, which leads to defects such as non-uniform patterning. The non-uniformity of the contact pressure of the conventional R2R NIL system was investigated through finite element (FE) analysis and experiments in the conventional system. To solve the problem, a new large-area R2R NIL uniform pressing system with five multi-backup rollers was proposed and manufactured instead of the conventional system. As a preliminary experiment, the possibility of uniform contact pressure was confirmed by using only the pressure at both ends and one backup roller in the center. A more even contact pressure was achieved by using all five backup rollers and applying an appropriate pushing force to each backup roller. Machine learning techniques were applied to find the optimal combination of the pushing forces. In the conventional pressing process, it was confirmed that pressure deviation of the contact area occurred at a level of 44%; when the improved system was applied, pressure deviation dropped to 5%

High-resolution printing of micrometer-scale copper electrode: From ink formulation and process optimization to application

In the rapidly advancing field of electronics, there is a growing demand for devices to be miniaturized with high-resolution patterns and compact, straightforward configurations, all while maintaining cost competitiveness. Precision patterning of conductive nano ink based on inexpensive metals offers an effective solution. This technique has proven compatibility with numerous integrated electronics. However, conventional patterning techniques face difficulties achieving high resolution, uniform thickness, and compatibility with environments prone to oxidation. Here, we optimize the reverse offset printing process and its ink formulation for green manufacturing of high-quality, high-resolution conductive micropatterns. The oleate ligand on the surface of Cu nanoparticles (CuNPs) is replaced by polyvinylpyrrolidone, which is more suitable for the steric stabilization of CuNPs in eco-friendly, polar solvent. Then, in consideration of the reverse offset printing mechanism, solvents and additives are evaluated to prepare a reverse offset printable ink. By examining the change in printability according to the composition and process parameters, we determine the printable composition range and process conditions. High-quality CuNP micropatterns with a fine line width of 10 μm, narrow spacing, sharp edge definition, and high uniformity are achieved. Finally, the reverse offset printed CuNP micropatterns are successfully implemented in thermistor microarrays as a potential application. © 2023 The AuthorsTRU