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Radiative cooling has proven to be a powerful strategy for sustainable thermal management. Nanophotonic structures enabling broadband reflection lead to minimization of sunlight absorption, which has brought nighttime-limited radiative cooling into daytime applications. However, this broadband reflection strategy in turn restricts the accessible colorization of radiative coolers to white or neutral, consequently hindering their practical applications, particularly for aesthetic purposes. With a few exceptions, selective absorption at a specific visible wavelength has been the most prevalent paradigm for colorization of radiative coolers. However, this absorption-based colorization inevitably makes the radiative cooler prone to heating, thus decreasing the cooling efficiency. Here, we demonstrate an undiscovered usage of opals for advancing color-preserved daytime radiative coolers. Opals, which have served mainly as Bragg reflective color pigments thus far, can be considered an effective homogeneous medium in the mid-infrared region. Thus, opals can also be envisioned as reflectively colorful metamaterials capable of radiative cooling even under the direct summer sun. Together with the soft fluidity of colloidal suspensions, opals can serve as platforms for easy-to-craft, large-scale, and colorful radiative coolers with minimal solar absorption.

Easy-to-craft photonic crystals enabling frequency-isolated Weyl points, especially at visible wavelengths, are yet to be developed. To this end, we exploited double gyroid (DG) crystals with Parit...

We describe a DNA base pair (bp) stacking driven 3D crystallization of 70-80 nm gold nanospheres (Au NSs) into a large-area, face-centered-cubic (FCC) lattice. Although great advances have been achieved over the past decade, DNA nanoparticle (NP) crystallization has relied solely on the base complementary binding. This limits the accessible crystal size particularly for the larger and heavier Au NPs (50 nm). In this work, we argue that the use of DNA bp-stacking (so-called blunt-end stacking) instead of complementary binding can widen the scope of controlled interparticle interactions used to assemble larger Au colloids into a larger-area crystal. Through the optimization of the melting transition, relatively large Au NSs (e.g., 75 nm) with nearly ideal roundness can be crystallized into FCC crystals with the area of up to approximately 1400 μm

The discrete element method (DEM) can be used to simulate the behavior of spherical particles. The spherical particles are regarded as rigid bodies in the calculation of DEM. However, the properties of these spherical particles are not applicable to powders consisting of plate-shaped or flaky particles because of the lack of geometrical consideration. Inevitably, the lack of geometrical consideration brings the misunderstanding of the powder flow with plate-shaped particles. In this research study, we suggest a new model, called flaky particles, consisting of a series of spherical particles to simulate the behavior of powder with spherical particles. To mimic the dynamic behavior of the hard particles, the relative motion of spherical particles, constituting a plate, is restricted. Afterwards, the suggested model is validated by the drop-and-bounce test and by theoretical results. The magnitude of the errors in the computation of the translational and the rotational velocities after collision are compared and the results show that the generated error is negligible (below 2%).

Summary Crystalline silicon (c-Si) is not used for developing transparent photovoltaics, owing to its opaque nature. Furthermore, adding optical transparency to a conventional c-Si wafer is one of the most challenging problems in this field. Here, we demonstrate the development of a neutral-colored transparent c-Si substrate using a 200-μm-thick c-Si wafer, which is known to be intrinsically opaque. Transparent c-Si substrates were fabricated by placing microhole-shaped light transmission windows on a bare c-Si wafer. These windows were designed to enable the transmission of all incident visible light through the substrate, resulting in a colorless substrate. A light absorption area was also designed on the wafer to efficiently absorb incident light. As a representative application, solar cells fabricated using the neutral-colored transparent c-Si substrate showed a power conversion efficiency of up to 12.2%. Therefore, our transparent c-Si solar cells present a unique opportunity to develop next-generation colorless transparent photovoltaics.

Desalination brine is a potential source for CO2 mineralization aimed at reducing CO2 emissions, because the concentration of Ca and Mg in brine is almost twice that of ordinary seawater. However, the previously achieved conversion ratio of CO2 to carbonate minerals is too low for commercial application, as Ca and Mg compete and interfere with each other during precipitation. In this study, we tested the separate and sequential mineralization of Ca and Mg in brine, enhancing the CO2 conversion ratio to 57% from 12%. We also tested the use of 15% CO2 gas (the typical concentration of actual combustion gas), and it was observed that 69% of injected CO2 was precipitated as Ca and Mg carbonate minerals and 99% of Ca and 69% of Mg in the initial brine were precipitated. In addition, the volume of NaOH solution required was reduced by 76%. This revised method is more material- and reagent-efficient which would likely have lower operation costs; moreover, as no further additives are required, environmental impact of brine release is also likely to be reduced. The findings of this study can help address environmental problems caused by large seawater desalination plants and thermal power plants.

BACKGROUND Autism spectrum disorder (ASD) is characterized by abnormalities in social communication and limited and repetitive behavioral patterns. Children with ASD who lack social communication skills will eventually not interact with others and will lack peer relationships when compared to ordinary people. Thus, it is necessary to develop a program to improve social communication abilities using digital technology in people with ASD. OBJECTIVE We intend to develop and apply a metaverse-based child social skills training program aimed at improving the social interaction abilities of children with ASD aged 7-12 years. We plan to compare and analyze the biometric information collected through wearable devices when applying the metaverse-based social skills training program to evaluate emotional changes in children with ASD in stressful situations. METHODS This parallel randomized controlled study will be conducted on children aged 7-12 years diagnosed with ASD. A metaverse-based social skills training program using digital technology will be administered to children who voluntarily wish to participate in the research with consent from their legal guardians. The treatment group will participate in the metaverse-based social skills training program developed by this research team once a week for 60 minutes per session for 4 weeks. The control group will not intervene during the experiment. The treatment group will use wearable devices during the experiment to collect real-time biometric information. RESULTS The study is expected to recruit and enroll participants in March 2022. After registering the participants, the study will be conducted from March 2022 to May 2022. This research will be jointly conducted by Yonsei University and Dobrain Co Ltd. Children participating in the program will use the internet-based platform. CONCLUSIONS The metaverse-based Program for the Education and Enrichment of Relational Skills (PEERS) will be effective in improving the social skills of children with ASD, similar to the offline PEERS program. The metaverse-based PEERS program offers excellent accessibility and is inexpensive because it can be administered at home; thus, it is expected to be effective in many children with ASD. If a method can be applied to detect children's emotional changes early using biometric information collected through wearable devices, then emotional changes such as anxiety and anger can be alleviated in advance, thus reducing issues in children with ASD. CLINICALTRIAL Clinical Research Information Service KCT0006859; https://tinyurl.com/4r3k7cmj INTERNATIONAL REGISTERED REPORT PRR1-10.2196/35960

An organoid array chip was developed by adopting a micropillar and microwell structure to test safety and efficacy of drugs using high dose drug heat map. In the chip, we encapsulated patient-derived cells in alginate and grow them to maturity for more than 7 days to form cancer organoids. When screening drug compounds in a high-density organoid array due to lack of number of patient-derived cells, changing media without damage of organoids is a very tedious and difficult process. Organoids grown in conventional well plates needed too many cells and were also easily damaged due to multiple pipetting during maintenance culture or during experimental procedures. To solve those problem, we applied a micropillar and microwell structure to the organoid array. We used patient-derived cells from patients with Glioblastoma multiforme (GBM), the most common and lethal form of central nervous system cancer, to validate the array chip performance. After forming more than 100µm-diameter organoids in 12 [[EQUATION]] 36 pillar array chip (25mm [[EQUATION]] 75mm), we tested 70 drug compounds (6 replicates) with high high-dose to find out high safety and efficacy drug candidates. Comparing the drug response of organoids derived from normal cells and cancer cells, we identified four compounds (Dacomitinib, Cediranib, Ly2835219, BGJ398) as drug candidates without toxicity to GBM cells.

Calcium carbonate is an earth-abundant biomineral that exists in a variety of marine environments, including corals, shells of mollusks, sea urchins, and so forth. Particularly, amorphous calcium c...

The enhanced electrochemical activity of nanostructured materials is readily exploited in energy devices, but their utility in scalable and human-compatible implantable neural interfaces can significantly advance the performance of clinical and research electrodes. We utilize low-temperature selective dealloying to develop scalable and biocompatible one-dimensional platinum nanorod (PtNR) arrays that exhibit superb electrochemical properties at various length scales, stability, and biocompatibility for high performance neurotechnologies. PtNR arrays record brain activity with cellular resolution from the cortical surfaces in birds and nonhuman primates. Significantly, strong modulation of surface recorded single unit activity by auditory stimuli is demonstrated in European Starling birds as well as the modulation of local field potentials in the visual cortex by light stimuli in a nonhuman primate and responses to electrical stimulation in mice. PtNRs record behaviorally and physiologically relevant neuronal dynamics from the surface of the brain with high spatiotemporal resolution, which paves the way for less invasive brain−machine interfaces.

To make a polymer-based material photosensitive, it is usually modified by inclusion of azobenzene (azo) chromophores. Their interaction with the light leads to conversion of absorbed energy into mechanical work. The wavelengths ∼500 nm induce cyclic trans-cis isomerization, which results in preferred orientation of the trans-isomers perpendicular to light polarization. This causes reorientation of the polymer backbones to which the azos are attached and appearance of the light-induced stress that dictates a direction of the macroscopic deformation. The directional photodeformations can be explained by an orientation approach, in which the reorientation of azos is described by the effective orientation potential. Here, we show how to calculate the time-dependent orientation state of the polymer backbones and the light-induced stress tensor. For side-chain azopolymers, a tensile stress in the direction of light polarization is predicted. Implementing the stress in a viscoplastic material model of the finite element software ANSYS, we show that a square azopolymer post elongates along the electric field vector for the linearly polarized light and contracts along the propagation direction for the circularly polarized light. These results of viscoplastic material modeling are in accordance with the experiments on light-induced reshaping of microscaled square and cylinder posts. Hence, the orientation approach works rather well for homogeneous illumination. We discuss how this approach can be used to describe surface deformations induced by complex light interference patterns.

Colloidal photonic crystals (CPCs), which possess intrinsic colourization characteristics due to their internal periodic structure, have been extensively exploited for various optical applications. However, conventional droplet-based synthesis of CPCs has shown simple structure and mono-colour generating properties since they generally require a protective shell as the outermost confining layer, and the lattice spacing inside the CPCs is invariantly determined, which hinders further tunability for structural and optically responsive properties. To enhance the tunability for structural and optically responsive properties of CPCs, here, we present a means to induce a spontaneous core-hatching process of selectively removing the CPC-encapsulating oil layer in double emulsion droplets by harnessing interfacial instability. By virtue of the reinforced interconnectivity between colloidal polyvinylpyrrolidone (PVP)-decorated polystyrene (PS) nanoparticles, isolated CPCs can retain their structural integrity even without a protective outer shell. As a result, the hatched CPCs can be further re-ordered into a core–shell-like structure having dual internal spacings and dual-colour generation properties. PVP chains decorated on the PS nanoparticles dictate the lattice spacing not only through solvent swelling but also by imparting structural stability via formation of hydrogen bonds. Furthermore, the degree of hatching of CPCs can be modulated to either core–shell-like CPCs (complete hatching) or Janus-like CPCs (partial hatching). Therefore, the work presented here offers a new approach to create uniquely structured and multicoloured CPCs with stimulus responsiveness while fully utilizing the advantages of the double emulsion templating method.

The self-assembly of metallic colloidal clusters (so called plasmonic metamolecules) has been viewed as a versatile, but highly effective approach for the materialization of the metamaterials exhibiting artificial magnetism at optical frequencies (including visible and near infrared (NIR) regimes). Indeed, several proofs of concepts of plasmonic metamolecules have been successfully demonstrated in both theoretical and experimental ways. Nevertheless, this self-assembly strategy has barely been used and still remains an underutilized method. For example, the self-assembly and optical utilization of the plasmonic metamolecules have been limited to the discrete unit of the structure; the materialization of effective optical medium made of plasmonic metamolecules is highly challenging. In this work, we theoretically exploited the practical limits of self-assembly technology for the fabrication of optical magnetic metamaterials.

Although DNA (low-cost, highly transparent, low optical loss, biodegradable, non-toxic, and highly flexible) and gold nanoparticles (Au NPs, exhibiting interband transition and localized surface plasmon resonance) have been intensively studied, DNA with Au NPs in photodetectors is rarely discussed. Here, we constructed salmon DNA (SDNA) thin films and incorporated Au NPs to demonstrate efficient and high-performance UV photodetectors. The Au NP-embedded SDNA thin films were characterized with UV–vis absorption, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and conductivity measurements in order to understand their physical and chemical properties. The FTIR and XPS measurements elucidated how Au NPs become embedded in SDNA, through analysis of chemical binding and chemical composition. A current increase was observed under UV illumination when performing conductivity measurements. In addition, photovoltage measurements were conducted to investigate the significance of photoresponse and retention characteristics. The density of d-band electrons in Au NPs and the charge carriers in SDNA were observed to increase under UV illumination, followed by a significantly enhanced UV photoresponse. From our observations, the photovoltage displayed a flat response over time, which indicated their stability, durability, and high Au NP retention.

Diffractive optical elements (DOE) and holograms based on diffractive optics use diffracted light generated by the interaction between light and the periodic structures such as gratings. For the fabrication of these structures, the researchers have widely used the materials that can modulate the refractive index. Recently, the photochromic materials have attracted a surge of interests for reversible holograms or DOE that can be controlled by light or heat. Especially, azobenzene molecules, which can undergo photo-isomerization under the specific wavelength of the light, are widely used for fabrication of surface relief gratings (SRGs). When the interference light is illuminated, azobenzene-containing polymer (azopolymer) films can form the SRGs via mass migration rather than lithographic etching. More strikingly, these already recorded SRGs as depending on mass migration, can be further inscribed via second mass migration, which can be also guided via another interference light. However, it has been accepted that this overwriting of SRGs needs to be performed after the erasing process of the already recorded SRGs. This limitation has in turn significantly restricted the hierarchical integration of the various SRGs with different structural features. In this work, we demonstrate that overwriting of SRGs on azopolymeric film can be possible without erasing of the previously recorded SRGs. By using this method, we can greatly advance not only the versatility of the process but also the accessible design of the SRGs and the resultant range of DOE-based light molding. In particularly, the pixelated SRGs with the unprecedented structural integrity can be achieved with a successive overwriting of SRGs without erasing process, which can serve to promote the augmented reality (AR) or virtual reality (VR) technologies.

High refractive index provides various benefits such as miniaturization of optical elements, enhancement of resolution for imaging techniques and utilization for transformative optics. In line with this, a lot of efforts have been taken to engineer and increase the refractive index (n). Especially, metamaterials have enabled to extremely increase the refractive index beyond the naturally occurring materials [1,2]. However, the high-index metamaterials, developed thus far, has been mainly limited to the regime of the relatively low frequency due to their easy-to-craft features (e.g., n of 38.64 at THz and ~1800 at microwave) [3,4]; an increase in n beyond the natural limit is yet to be achieved at optical regimes. The monolithic lithography, which has been a major tool for the development of the metamaterials, would be difficult to satisfy the requirements for achieving unnaturally high n at optical range, including the arraying of sub-100 nm building blocks with a few nm-gaps over the

Plasmonic polymers consisting of metallic nanoparticles (NPs) are able to squeeze light into the deep-subwavelength space and transfer along a highly confined nanoscale path in long range. DNA nanotechnology, particularly benefiting from the molecular programmability of DNA origami, has provided otherwise nearly impossible platforms for constructing plasmonic nanoparticle polymers with designer configurations and nanoscale gaps. Here, we design and assemble a DNA origami hashtag tile that is able to polymerize into one-dimensional chains with high rigidity. The DNA origami hashtag chains are used as frames to enable robust, versatile, and precise arrangement of metallic NPs into micrometer-long chiral and magnetic plasmonic polymers, which are capable of efficiently transporting plasmonic angular momentum and magnetic surface plasmonic polaritons at the deep-subwavelength scale. Our work provides a molecular platform for the fabrication of long, straight, and structurally complex nanoparticle polymers with emerging plasmonic properties that are appealing to a variety of fields.

DNA origami, in which a long scaffold strand is assembled with a many short staple strands into parallel arrays of double helices, has proven a powerful method for custom nanofabrication. However, currently the design and optimization of custom 3D DNA-origami shapes is a barrier to rapid application to new areas. Here we introduce a modular barrel architecture, and demonstrate hierarchical assembly of a 100 megadalton DNA-origami barrel of ~90 nm diameter and ~250 nm height, that provides a rhombic-lattice canvas of a thousand pixels each, with pitch of ~8 nm, on its inner and outer surfaces. Complex patterns rendered on these surfaces were resolved using up to twelve rounds of Exchange-PAINT super-resolution microscopy. We envision these structures as versatile nanoscale pegboards for applications requiring complex 3D arrangements of matter, which will serve to promote rapid uptake of this technology in diverse fields beyond specialist groups working in DNA nanotechnology., The design and optimisation of 3D DNA-origami can be a barrier to rapid application. Here the authors design barrel structure of stacked 2D double helical rings with complex surface patterns.

Identifying the cause of inconsistent landfarming efficacy is critical to designing optimal remedial strategies for petroleum-contaminated sites. We assessed contaminated soils collected from two former military bases in South Korea to better understand the role and influence of different factors. Landfarming remediation was simulated in the laboratory by applying comparable practices (such as tillage and bioaugmentation) and the relevant mechanism was examined. We then systematically examined potential factors affecting petroleum-removal efficacy, including the content of fine soil particles, the initial concentration and composition of petroleum contaminants, and the degree of soil-contaminant interaction. The distribution range of total petroleum hydrocarbons (TPHs) and the size of unresolved complex mixture (UCM) found in gas chromatography data showed that petroleum composed of TPHs with lower carbon numbers and having smaller size of UCM could be treated more effectively by landfarming. Incorporating the evaluation of the distribution range and UCM properties of petroleum, rather than simply considering its total concentration, is a more accurate and efficient method for determining the site-specific suitability of landfarming as a remedial option, as well as for assessing the necessity of supplementary processes.

Hf0.5Zr0.5O2 (HZO) is an appropriate material for the back-end-of-line (BEOL) process in fabricating ferroelectric TiN/HZO/TiN devices because of its excellent conformality on 3D nanostructures and a suitable crystallization temperature (≥ 350 °C–400 °C). However, in the semiconductor industry, the deposition temperature of TiN is usually higher than 400 °C. Therefore, it is necessary to study the ferroelectric properties of TiN/HZO/TiN devices when the deposition temperature of the TiN top electrode is higher than the HZO film crystallization temperature. In this study, 10-nm-thick TiN top electrodes were deposited at various temperatures on the HZO thin film to investigate the impact of the TiN deposition temperature on the structural features and ferroelectric properties of TiN/HZO/TiN capacitors. Only the sample capped with a TiN top electrode deposited at 400 °C showed ferroelectric properties without subsequent annealing (in situ crystallization). However, this sample exhibited an approximately 40% reduction in the polarization value compared with the other samples that were crystallized after the annealing process. This behavior can be ascribed to the formation of a monoclinic nonpolar phase. To prevent the degradation of the polarization value and suppress the formation of the m-phase in the in situ crystallized HZO thin film, a two-step TiN deposition method was carried out. The sample was fabricated by depositing a 5-nm-thick TiN top electrode at room temperature followed by the deposition of a 5-nm-thick TiN layer at 400 °C, which resulted in strong ferroelectric properties comparable to those of the samples capped with TiN grown at relatively low temperatures (room temperature, 200 °C, and 300 °C). These findings can adequately explain the role of the capping layer in achieving the ferroelectric phase, which is closely related not only during the cooling step of any thermal process but also during the heating and crystallization steps.

Despite ongoing advances in our understanding of local single-cellular and network-level activity of neuronal populations in the human brain, extraordinarily little is known about their “intermediate” microscale local circuit dynamics. Here, we utilized ultra-high-density microelectrode arrays and a rare opportunity to perform intracranial recordings across multiple cortical areas in human participants to discover three distinct classes of cortical activity that are not locked to ongoing natural brain rhythmic activity. The first included fast waveforms similar to extracellular single-unit activity. The other two types were discrete events with slower waveform dynamics and were found preferentially in upper cortical layers. These second and third types were also observed in rodents, nonhuman primates, and semi-chronic recordings from humans via laminar and Utah array microelectrodes. The rates of all three events were selectively modulated by auditory and electrical stimuli, pharmacological manipulation, and cold saline application and had small causal co-occurrences. These results suggest that the proper combination of high-resolution microelectrodes and analytic techniques can capture neuronal dynamics that lay between somatic action potentials and aggregate population activity. Understanding intermediate microscale dynamics in relation to single-cell and network dynamics may reveal important details about activity in the full cortical circuit.