Spatially Programmable Chirality in Cellulose Nanocrystal Films via Rotational Magnetic Flow.

Programmed assembly of natural materials on a large scale is often limited by inherent factors, including dimensional dispersity, complex hierarchical organization, and slow processing kinetics. In this study, we demonstrate a scalable strategy to preprogram the chiral assembly of cellulose nanocrystals (CNCs) by applying a rotational magnetic field during evaporation-induced self-assembly. To facilitate magnetic responsiveness, CNCs are decorated with magnetic nanoparticles and subjected to a rotational magnetic field.

Spatially patterned stiffness variation in a light-triggered jumper for symmetry breaking and high snap-through efficiency.

The nonlinear strain response of soft material-based snap-through systems enables amplified and accelerated force output. However, efficiency of snap-through energy release is challenging to improve because of the inherent trade-off between initial curvature and stiffness. Here, spatial programming of stiffness variation in the azobenzene-functionalized liquid-crystalline polymer (Azo-LCP) addresses this limitation and achieves efficient photomechanical jumping.

Robust Skin-Conformal Nano-Electrodes for Sustainable Health and Performance Monitoring.

Wearable electrodes with high conformability to the skin allow for a second-skin-like wearing experience and record high-quality electrophysiological signals over extended time in challenging environments. However, current research on skin-conformal electrodes faces limitations due to excessive motion artifacts under real-life external conditions. Here, we report a nanoscale skin-conformal electrode that enables continuous resilient electrophysiological signal monitoring with highly suppressed noise, low-motion artifacts, and high water-resilience, all unachievable with commercial gel electrodes.

Piezo-ionic Materials and Structures for Complex Shear Field Monitoring.

Capturing shearing stresses is crucial for accurately monitoring multidirectional mechanical deformation, enabling advanced motion analysis and enhancing functionality in wearable and robotic applications. Here, we present self-powered porous piezo-ionic shear-sensing materials that simultaneously resolve normal and tangential stresses with high sensitivity, a broad dynamic range, and high linearity. A composite of thermoplastic urethane and ionic liquids, reinforced with silica nanoparticles, was exploited to establish and sustain a porous framework.

Collective and Rapid High Amplitude Magnetic Oscillation of Anisotropic Micropillar Arrays.

Magnetic soft actuators allow high-frequency shape reconfiguration of the micropillar array by rapid rotation of an external magnetic field; however, viscoelastic soft actuators cannot instantaneously reach an equilibrium deformation state to minimize the magnetic moment at a given short time scale, resulting in a significant reduction of the strain amplitude. Herein, we report high-frequency magnetic oscillation of a micropillar array without significant reduction in frequency or strain amplitude by programming the magnetization direction of hard magnetic microparticles embedded in a soft elastomer. Various oscillatory motions, including bending, twisting, and torsion under time-varying external magnetic fields, are demonstrated via programming the magnetization of anisotropic micropillars.

Magneto-Responsive Chiral Optical Materials: Flow-Induced Twisting of Cellulose Nanocrystals in Patterned Magnetic Fields.

Magnetic fields have been used to uniformly align the lyotropic chiral nematic (cholesteric) liquid crystalline (LC) phase of biopolymers to a global orientation and optical appearance. Here, we demonstrate that, in contrast, weak and patterned magnetic field gradients can create a complex optical appearance with the variable spatial local organization of needle-like magnetically decorated cellulose nanocrystals. The formation of optically patterned thin films with left- and right-handed chiral and achiral regions is observed and related to local magnetic gradient-driven vortices during LC suspension flow.

Double-Sided Pressure-Sensitive Adhesive Materials under Human-Centric Extreme Environments.

Maintaining the adhesion strength of flexible pressure-sensitive adhesives (PSAs) is crucial for advanced applications, such as health monitoring. Sustainable mounting is critical for wearable sensor devices, especially under challenging surroundings such as low and high temperatures (e.g.

Fine dust inflow paths and heating load variation based on field measurement of air tightness in two Korean schools.

This study aimed to determine the effects of fine dust reduction, as well as the energy load reduction in association with the improvement plans by measuring the airtightness and indoor and outdoor fine dust concentrations in middle and high school classrooms and by identifying the fine dust inflow paths. The air tightness and indoor and outdoor fine dust concentrations were measured at two schools, and the paths of outdoor fine dust inflow were identified for an extensive analysis of the effects of fine dust reduction and the energy load reduction in association with improvement plans. Air tightness in the classroom at school A and B was improved by 32.

Machine learning based prediction of recurrence after curative resection for rectal cancer.

Purpose: Patients with rectal cancer without distant metastases are typically treated with radical surgery. Post curative resection, several factors can affect tumor recurrence. This study aimed to analyze factors related to rectal cancer recurrence after curative resection using different machine learning techniques.

Steerable and Agile Light-Fueled Rolling Locomotors by Curvature-Engineered Torsional Torque.

On-demand photo-steerable amphibious rolling motions are generated by the structural engineering of monolithic soft locomotors. Photo-morphogenesis of azobenzene-functionalized liquid crystal polymer networks (azo-LCNs) is designed from spiral ribbon to helicoid helices, employing a 270° super-twisted nematic molecular geometry with aspect ratio variations of azo-LCN strips. Unlike the intermittent and biased rolling of spiral ribbon azo-LCNs with center-of-mass shifting, the axial torsional torque of helicoid azo-LCNs enables continuous and straight rolling at high rotation rates (≈720 rpm).

A review on indoor airborne transmission of COVID-19- modelling and mitigation approaches.

In the past few years, significant efforts have been made to investigate the transmission of COVID-19. This paper provides a review of the COVID-19 airborne transmission modeling and mitigation strategies. The simulation models here are classified into airborne transmission infectious risk models and numerical approaches for spatiotemporal airborne transmissions.

Multi-Modal Locomotion of Caenorhabditis elegans by Magnetic Reconfiguration of 3D Microtopography.

Miniaturized untethered soft robots are recently exploited to imitate multi-modal curvilinear locomotion of living creatures that perceive change of surrounding environments. Herein, the use of Caenorhabditis elegans (C. elegans) is proposed as a microscale model capable of curvilinear locomotion with mechanosensing, controlled by magnetically reconfigured 3D microtopography.

On-Demand Dynamic Chirality Selection in Flower Corolla-like Micropillar Arrays.

Chiral morphology has been intensively studied in various fields including biology, organic chemistry, pharmaceuticals, and optics. On-demand and dynamic chiral inversion not only cannot be realized in most intrinsically chiral materials but also has mostly been limited to chemical or light-induced methods. Herein, we report reversible real-time magneto-mechanical chiral inversion of a three-dimensional (3D) micropillar array between achiral, clockwise, and counterclockwise chiral arrangements.

Height-Tunable Replica Molding Using Viscous Polymeric Resins.

Replica molding is one of the most common and low-cost methods for constructing microstructures for various applications, including dry adhesives, optics, tissue engineering, and strain sensors. However, replica molding provides only a single-height microstructure from a mold and master molds produced by an expensive photolithography process are required to prepare microstructures with different heights. Herein, we present a strategy to control the height of micropillars from the same mold by varying the cavity size of the micromold and the viscosity of the photocurable polyimide resin.

Programmable Liquid Crystal Defect Arrays via Electric Field Modulation for Mechanically Functional Liquid Crystal Networks.

The arrangement of mesogenic units determines mechanical response of the liquid crystal polymer network (LCN) film to heat. Here, we show an interesting approach to programming three-dimensional patterns of the LCN films with periodic topological defects generated by applying an electric field. The mechanical properties of three representative patterned LCN films were investigated in terms of the arrangement of mesogenic units through tensile testing.

Effect of eco-friendly pervious concrete with amorphous metallic fiber on evaporative cooling performance.

Impervious pavements exist in large proportions in most cities owing to the high-impact development of the transportation infrastructure. However, this type of pavement causes environmental issues such as waterlogging, floods, and urban heat islands. Pervious concrete (PC), which is a novel pavement material characterized by a porous structure that allows water to percolate through it, is an important solution to these issues.

Evaluation of thermal properties and acetaldehyde adsorption performance of sustainable composites using waste wood and biochar.

In order to vitalize the use of wood, which is a sustainable resource, increase the utilization of resources through the recycling of wood waste, and reduce environmental pollution in the waste disposal process, biocomposite was manufactured by using biochar which can be produced with wood waste and is effective in carbon isolation. The thermal characteristics and acetaldehyde adsorption performance of the prepared biocomposite were evaluated based on the pore characteristics, surface functional groups, crystal structure, and elemental analysis results of the biochar. As a result of the experiment, as the content of biochar increased, the thermal conductivity of the biocomposite decreased and the specific heat was not affected.

Analysis of biochar-mortar composite as a humidity control material to improve the building energy and hygrothermal performance.

This study suggests a new perspective of biochar as a building material that improve not only for the strength but also hygrothermal properties. Biochar has a high porosity and surface area created by pyrolysis. It can be suitably used as a porous material because porous materials are used by incorporating into building materials for improving hygrothermal performance in the construction sector.

Electrocatalytic Oxidation of Methanol by a Polymeric Ni Complex-Modified Electrode Prepared by a One-Step Cold-Plasma Process.

In this work, a polymeric nickel complex-modified indium tin oxide (ITO) electrode was prepared by a one-step cold-plasma process of acrylic-Ni complex precursors. Also, the work provides the electrocatalytic oxidation of methanol by a polymeric Ni complex-modified electrode prepared by a simple one-step cold-plasma process. The acrylic-Ni complex precursors were synthesized by complexation of nickel (II) chloride, and acrylic acid in a small amount of water; subsequently we added N,N'-methylene-bis-acrylamide as a crosslinking agent to the complex solution.

High crystallinity of tunicate cellulose nanofibers for high-performance engineering films.

Tunicate cellulose nanofibers (CNFs) have received widespread attention as renewable and eco-friendly engineering materials because of their high crystallinity and mechanical stiffness. Here, we report the effects of disintegration process conditions on structure-property relationships of tunicate CNFs. By varying the hydrolysis time, we could establish a correlation between crystallinity of the CNFs with linearity and stiffness, which produces different molecular ordering within their nanostructured films.

High-Speed Production of Crystalline Semiconducting Polymer Line Arrays by Meniscus Oscillation Self-Assembly.

Evaporative self-assembly of semiconducting polymers is a low-cost route to fabricating micrometer and nanoscale features for use in organic and flexible electronic devices. However, in most cases, rate is limited by the kinetics of solvent evaporation, and it is challenging to achieve uniformity over length- and time-scales that are compelling for manufacturing scale-up. In this study, we report high-throughput, continuous printing of poly(3-hexylthiophene) (P3HT) by a modified doctor blading technique with oscillatory meniscus motion-meniscus-oscillated self-assembly (MOSA), which forms P3HT features ∼100 times faster than previously reported techniques.

Evaluation of hygrothermal performance of wood-derived biocomposite with biochar in response to climate change.

Wood is a sustainable resource and building material. It provides an excellent response to climate change and has excellent insulation performance. However, structural defects may occur due to decay from moisture, resulting in poor dimensional stability.

Enhancement of Magneto-Mechanical Actuation of Micropillar Arrays by Anisotropic Stress Distribution.

Magnetically active shape-reconfigurable microarrays undergo programmed actuation according to the arrangement of magnetic dipoles within the structures, achieving complex twisting and bending deformations. Cylindrical micropillars have been widely used to date, whose circular cross-sections lead to identical actuation regardless of the actuating direction. In this study, micropillars with triangular or rectangular cross-sections are designed and fabricated to introduce preferential actuation directions and explore the limits of their actuation.

Shape-Programmed Fabrication and Actuation of Magnetically Active Micropost Arrays.

Micro- and nanotextured surfaces with reconfigurable textures can enable advancements in the control of wetting and heat transfer, directed assembly of complex materials, and reconfigurable optics, among many applications. However, reliable and programmable directional shape in large scale is significant for prescribed applications. Herein, we demonstrate the self-directed fabrication and actuation of large-area elastomer micropillar arrays, using magnetic fields to both program a shape-directed actuation response and rapidly and reversibly actuate the arrays.

Field study on the improvement of indoor air quality with toluene adsorption finishing materials in an urban residential apartment.

To improve the indoor air quality of apartments in Korea, a toluene adsorptive paint was manufactured and tested for its efficiency to remove the indoor toluene released from wallpaper adhesives. The toluene adsorptive paint was prepared by blending activated carbon and inorganic binder, and the pore characteristics and chemical functional groups of the activated carbon were analyzed to determine whether the micropores and surface functionalities of activated carbon affected toluene adsorption. Toluene adsorption performance of the toluene adsorptive paint was confirmed through static and verification experiments.