Colloidal quasicrystals engineered with DNA.

In principle, designing and synthesizing almost any class of colloidal crystal is possible. Nonetheless, the deliberate and rational formation of colloidal quasicrystals has been difficult to achieve. Here we describe the assembly of colloidal quasicrystals by exploiting the geometry of nanoscale decahedra and the programmable bonding characteristics of DNA immobilized on their facets. This process is enthalpy-driven, works over a range of particle sizes and DNA lengths, and is made possible by the energetic preference of the system to maximize DNA duplex formation and favour facet alignment, generating local five- and six-coordinated motifs. This class of axial structures is defined by a square-triangle tiling with rhombus defects and successive on-average quasiperiodic layers exhibiting stacking disorder which provides the entropy necessary for thermodynamic stability. Taken together, these results establish an engineering milestone in the deliberate design of programmable matter.

Health-promoting behavior among undergraduate students in the COVID-19 era: Its association with problematic use of social media, social isolation, and online health information-seeking behavior.

OBJECTIVE: To examine the association between problematic use of social media, online health information-seeking, social isolation, and health-promoting behaviors among Korean undergraduate students. METHODS: In total, 178 undergraduate students participated in this study. A multiple linear regression analysis was performed. RESULTS: Predictors of health-promoting behaviors included overall time spent on social media, problematic social media use, social isolation, and online information-seeking, explaining 33.5 % of the variance in health-promoting behaviors. CONCLUSION: Prolonged social media use and social isolation negatively affected undergraduate students' health-promoting behaviors, while online information-seeking positively affected them. Nurses should assist young adults in improving health-promoting behaviors by preventing problematic social media uses, reducing social isolation, and strengthening their online health information-seeking ability.

Engineering the Thermodynamic Stability and Metastability of Mesophases of Colloidal Bipyramids through Shape Entropy.

We report several types of entropy-driven phase transition behaviors in hard bipyramid systems using Monte Carlo simulations. Bipyramidal nanoparticle shapes are synthesizable from gold and silver, with sizes ranging from tens to hundreds of nanometers. We report numerous colloidal crystalline phases with varying symmetries and complexities as the bipyramid aspect ratio and base polygon are varied. Some bipyramids are mesogenic and undergo either monotropic or enantiotropic phase transitions. We show that such mesophase behavior can be modulated by tuning the bipyramid aspect ratio. In addition, we report stepwise kinetic crystallization and melting pathways that occur via an intermediate mesophase as the system gains or loses order in successive stages. Our results demonstrate that complex phase transition behavior involving mesophases can be driven by entropy alone. Importantly, our results can guide the synthesis of bipyramid shapes able to assemble target structures and can be used to engineer the kinetic pathways to and from those structures to involve or avoid mesophases.

Validation of a liquid chromatography tandem mass spectrometry method to measure oxidized and reduced forms of glutathione in whole blood and verification in a mouse model as an indicator of oxidative stress.

As a possible marker of oxidative stress, many studies have measured whole blood reduced glutathione (GSH) and oxidized glutathione (GSSG). However, large differences in GSH and GSSG levels reported in different studies, calls for a reliable standardized method. In this study, we validate not only analytical performance of new measurement method for GSH and GSSG, but also the clinical utility of these markers in a mouse model with chronic oxidative stress. Twenty mice were randomized into four treatment groups according to iron burden: 0mg, 5mg, 10mg, or 15 mg of iron were injected into the peritoneum per day over 4 weeks. To prevent artifactual GSH auto-oxidation, we pretreated the sample with N-ethylmaleimide (NEM) immediately after sample collection. After protein precipitation using sulfosalicylic acid, GSSG and GSH-NEM were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The mean GSH/GSSG ratios of the mouse model were 163.1, 31.0, 27.9, and 12.8 for control, 5mg, 10mg, and 15 mg injection groups, respectively, showing a decrease in the GSH/GSSG ratios according to the amount of oxidative stress induced. Inter-assay coefficients of variation were 4.1% for GSH-NEM and 7.3% for GSSG. Recoveries were 98.0-105.9% for GSH-NEM and 98.0-107.3% for GSSG. No ion suppression was observed at the retention time for GSH-NEM and GSSG. This study suggests an accurate method that can be used for glutathione measurement using LC-MS/MS, and showed that GSH/GSSG ratio could provide an assessment of the degree of oxidative stress.

Biaxially stretchable, integrated array of high performance microsupercapacitors.

We report on the fabrication of a biaxially stretchable array of high performance microsupercapacitors (MSCs) on a deformable substrate. The deformable substrate is designed to suppress local strain applied to active devices by locally implanting pieces of stiff polyethylene terephthalate (PET) films within the soft elastomer of Ecoflex. A strain suppressed region is formed on the top surface of the deformable substrate, below which PET films are implanted. Active devices placed within this region can be isolated from the strain. Analysis of strain distribution by finite element method confirms that the maximum strain applied to MSC in the strain suppressed region is smaller than 0.02%, while that on the Ecoflex film is larger than 250% under both uniaxial strain of 70% and biaxial strain of 50%. The all-solid-state planar MSCs, fabricated with layer-by-layer deposited multiwalled carbon nanotube electrodes and patterned ionogel electrolyte of poly(ethylene glycol) diacrylate and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide having high-potential windows, are dry-transferred onto the deformable substrate and electrically connected in series and parallel via embedded liquid metal interconnection and Ag nanowire contacts. Liquid metal interconnection, formed by injecting liquid metal into the microchannel embedded within the substrate, can endure severe strains and requires no additional encapsulation process. This formed MSC array exhibits high energy and power density of 25 mWh/cm(3) and 32 W/cm(3), and stable electrochemical performance up to 100% uniaxial and 50% biaxial stretching. The high output voltage of the MSC array is used to light micro-light-emitting diode (µ-LED) arrays, even under strain conditions. This work demonstrates the potential application of our stretchable MSC arrays to wearable and bioimplantable electronics with a self-powered system.

Design and fabrication of novel stretchable device arrays on a deformable polymer substrate with embedded liquid-metal interconnections.

Stretchable devices are fabricated on a newly designed deformable substrate. Active devices attached on the stiff islands are electrically connected by an embedded EGaIn interconnection, which ensures protection from external damage. In this structure, the local strain in the active device area is estimated to be less than 1% under applied strain of 30% by analysis of the strain distribution using the finite element method.

High-density, stretchable, all-solid-state microsupercapacitor arrays.

We report on the successful fabrication of stretchable microsupercapacitor (MSC) arrays on a deformable polymer substrate that exhibits high electrochemical performance even under mechanical deformation such as bending, twisting, and uniaxial strain of up to 40%. We designed the deformable substrate to minimize the strain on MSCs by adopting a heterogeneous structure consisting of stiff PDMS islands (on which MSCs are attached) and a soft thin film (mixture of Ecoflex and PDMS) between neighboring PDMS islands. Finite element method analysis of strain distribution showed that an almost negligible strain of 0.47% existed on the PDMS islands but a concentrated strain of 107% was present on the soft thin film area under a uniaxial strain of 40%. The use of an embedded interconnection of the liquid metal Galinstan helped simplify the fabrication and provided mechanical stability under deformation. Furthermore, double-sided integration of MSCs increased the capacitance to twice that of MSCs on a conventional planar deformable substrate. In this study, planar-type MSCs with layer-by-layer assembled hybrid thin film electrodes of MWNT/Mn3O4 and PVA-H3PO4 electrolyte were fabricated; when they are integrated into a circuit, these MSCs increase the output voltage beyond the potential of the electrolyte used. Therefore, various LEDs that require high voltages can be operated under a high uniaxial strain of 40% without any decrease in their brightness. The results obtained in this study demonstrate the high potential of our stretchable MSC arrays for their application as embedded stretchable energy storage devices in bioimplantable and future wearable nanoelectronics.