ELONGATED HYPOCOTYL 5 interacts with HISTONE DEACETYLASE 9 to suppress glucosinolate biosynthesis in Arabidopsis.

Glucosinolates (GSLs) are defensive secondary metabolites produced by Brassicaceae species in response to abiotic and biotic stresses. The biosynthesis of GSL compounds and the expression of GSL-related genes are highly modulated by endogenous signals (i.e., circadian clocks) and environmental cues, such as temperature, light, and pathogens. However, the detailed mechanism by which light signaling influences GSL metabolism remains poorly understood. In this study, we found that a light-signaling factor, ELONGATED HYPOCOTYL 5 (HY5), was involved in the regulation of GSL content under light conditions in Arabidopsis (Arabidopsis thaliana). In hy5-215 mutants, the transcript levels of GSL pathway genes were substantially upregulated compared with those in wild-type plants. The content of GSL compounds was also substantially increased in hy5-215 mutants, whereas 35S::HY5-GFP/hy5-215 transgenic lines exhibited comparable levels of GSL-related transcripts and GSL content to those in WT plants. HY5 physically interacts with HISTONE DEACETYLASE9 (HDA9) and binds to the proximal promoter region of MYB29 and IMD1 to suppress aliphatic GSL biosynthetic processes. These results demonstrate that HY5 suppresses GSL accumulation during the daytime, thus properly modulating GSL content daily in Arabidopsis plants.

Microstructural characterization and inductively coupled plasma-reactive ion etching resistance of Y2O3-Y4Al2O9 composite under CF4/Ar/O2 mixed gas conditions.

In the semiconductor manufacturing process, when conducting inductively coupled plasma-reactive ion etching in challenging environments, both wafers and the ceramic components comprising the chamber's interior can be influenced by plasma attack. When ceramic components are exposed to long-term plasma environments, the eroded components must be replaced. Furthermore, non-volatile reactants can form and settle on semiconductor chips, acting as contaminants and reducing semiconductor production yield. Therefore, for semiconductor processing equipment parts to be utilized, it is necessary that they exhibit minimized generation of contaminant particles and not deviate significantly from the composition of conventionally used Al2O3 and Y2O3; part must also last long in various physicochemical etching environment. Herein, we investigate the plasma etching behavior of Y2O3-Y4Al2O9 (YAM) composites with a variety of mixing ratios under different gas fraction conditions. The investigation revealed that the etching rates and changes in surface roughness for these materials were significantly less than those of Y2O3 materials subjected to both chemical and physical etching. Microstructure analysis was conducted to demonstrate the minimization of crater formation. Mechanical properties of the composite were also analyzed. The results show that the composite can be commercialized as next-generation ceramic component in semiconductor processing equipment applications.

Phytochrome phosphorylation in plant light signaling.

Plant phytochromes, renowned phosphoproteins, are red and far-red photoreceptors that regulate growth and development in response to light signals. Studies on phytochrome phosphorylation postulate that the N-terminal extension (NTE) and hinge region between N- and C-domains are sites of phosphorylation. Further studies have demonstrated that phosphorylation in the hinge region is important for regulating protein-protein interactions with downstream signaling partners, and phosphorylation in the NTE partakes in controlling phytochrome activity for signal attenuation and nuclear import. Moreover, phytochrome-associated protein phosphatases have been reported, indicating a role of reversible phosphorylation in phytochrome regulation. Furthermore, phytochromes exhibit serine/threonine kinase activity with autophosphorylation, and studies on phytochrome mutants with impaired or increased kinase activity corroborate that they are functional protein kinases in plants. In addition to the autophosphorylation, phytochromes negatively regulate PHYTOCHROME-INTERACTING FACTORs (PIFs) in a light-dependent manner by phosphorylating them as kinase substrates. Very recently, a few protein kinases have also been reported to phosphorylate phytochromes, suggesting new views on the regulation of phytochrome via phosphorylation. Using these recent advances, this review details phytochrome regulation through phosphorylation and highlights their significance as protein kinases in plant light signaling.

Distribution of sika deer (Cervus nippon) and the bioclimatic impact on their habitats in South Korea.

Invasive species and climate change are primary factors influencing biodiversity, and examining the behavior of invasive species is essential for effective conservation management. Here, we report the global distribution of the sika deer (Cervus nippon) based on locations reported in published literature (Google Scholar), the Global Biodiversity Information Facility (GBIF) database, and the International Union for Conservation of Nature report. We used the maximum entropy (Maxent) model to examine the impact of climate change on sika deer habitats in South Korea based on GBIF occurrence data and WorldClim bioclimatic variables. Habitat suitability analysis was performed using the Maxent model under Representative Concentration Pathways (RCPs) 4.5 and 8.5 (for predicted climatic conditions in both 2050 and 2070) to project the effects of different climate change scenarios on South Korean sika deer habitats. We identified that the sika deer is distributed in 39 countries worldwide. Due to climate change effects, South Korean sika deer habitats will decline by approximately 24.98% and 20.63% (under RCP 4.5) and by 50.51% and 57.35% (under RCP 8.5) by 2050 and 2070, respectively. Our findings shed light on sika deer ecology and provide reference data for future conservation management strategies and policy design.

Classification of fNIRS signals from adolescents with MDD in suicide high- and low-risk groups using machine learning.

Prefrontal cortex activation is attenuated during cognitive tasks in patients with suicidal ideation or major depressive disorder (MDD). However, the apparent relationship between patients with MDD, especially suicide high-risk (SHR) adolescents, and the characteristics of their hemodynamic responses has not yet been elucidated. To investigate this relationship, we recruited 30 patients with MDD aged 13-19. Functional near-infrared spectroscopy (fNIRS) data were collected for all patients during a Stroop test. Through a ten-time iterative leave-one-out cross-validation via 1000 iterative random search-based feature selections, we achieved a generalized classification accuracy of 70.3±5.0 % (from min. 63.3 % to max. 76.7 %). From the results of random search-based feature selection, Ch08oxy and Ch09deoxy were identified as the two most relevant fNIRS channels. This finding implies that these fNIRS channels can be used as neurological biomarkers to distinguish SHR adolescents with MDD from suicide low-risk (SLR) adolescents. In addition, we determined the oxy-Hb channels of the SHR group, except for Ch01oxy, Ch02oxy, Ch11oxy, and Ch14oxy, were hyperactivated compared to the SLR group.

A Bioactive Compound-Loaded Zinc-Aminoclay Encapsulated, Pickering Emulsion System for Treating Acne-Inducing Microbes.

Acne is a common skin condition caused by the growth of certain bacteria. Many plant extracts have been investigated for their potential to combat acne-inducing microbes, and one such plant extract is microwave-assisted Opuntia humifusa extract (MA-OHE). The MA-OHE was loaded onto zinc-aminoclay (ZnAC) and encapsulated in a Pickering emulsion system (MA-OHE/ZnAC PE) to evaluate its therapeutic potential against acne-inducing microbes. Dynamic light scattering and scanning electron microscopy were used to characterize MA-OHE/ZnAC PE with a mean particle diameter of 353.97 nm and a PDI of 0.629. The antimicrobial effect of MA-OHE/ZnAC was evaluated against Staphylococcus aureus (S. aureus) and Cutibacterium acnes (C. acnes), which contribute to acne inflammation. The antibacterial activity of MA-OHE/ZnAC was 0.1 and 0.025 mg/mL to S. aureus and C. acnes, respectively, which were close to naturally derived antibiotics. Additionally, the cytotoxicity of MA-OHE, ZnAC, and MA-OHE/ZnAC was tested, and the results showed that they had no cytotoxic effects on cultured human keratinocytes in a range of 10-100 µg/mL. Thus, MA-OHE/ZnAC is suggested to be a promising antimicrobial agent for treating acne-inducing microbes, while MA-OHE/ZnAC PE is a potentially advantageous dermal delivery system.

Three-Dimensional Printing of Structural Color Using a Femtoliter Meniscus.

Structural colors are produced by the diffraction of light from microstructures. The collective arrangement of substructures is a simple and cost-effective approach for structural coloration represented by colloidal self-assembly. Nanofabrication methods enable precise and flexible coloration by processing individual nanostructures, but these methods are expensive or complex. Direct integration of desired structural coloration remains difficult because of the limited resolution, material-specificity, or complexity. Here, we demonstrate three-dimensional printing of structural colors by direct writing of nanowire gratings using a femtoliter meniscus of polymer ink. This method combines a simple process, desired coloration, and direct integration at a low cost. Precise and flexible coloration is demonstrated by printing the desired structural colors and shapes. In addition, alignment-resolved selective reflection is shown for displayed image control and color synthesis. The direct integration facilitates structural coloration on various substrates, including quartz, silicon, platinum, gold, and flexible polymer films. We expect that our contribution can expand the utility of diffraction gratings across various disciplines such as surface-integrated strain sensors, transparent reflective displays, fiber-integrated spectrometers, anticounterfeiting, biological assays, and environmental sensors.

Regulation of Plant Photoresponses by Protein Kinase Activity of Phytochrome A.

Extensive research has been conducted for decades to elucidate the molecular and regulatory mechanisms for phytochrome-mediated light signaling in plants. As a result, tens of downstream signaling components that physically interact with phytochromes are identified, among which negative transcription factors for photomorphogenesis, PHYTOCHROME-INTERACTING FACTORs (PIFs), are well known to be regulated by phytochromes. In addition, phytochromes are also shown to inactivate an important E3 ligase complex consisting of CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and SUPPRESSORs OF phyA-105 (SPAs). This inactivation induces the accumulation of positive transcription factors for plant photomorphogenesis, such as ELONGATED HYPOCOTYL 5 (HY5). Although many downstream components of phytochrome signaling have been studied thus far, it is not fully elucidated which intrinsic activity of phytochromes is necessary for the regulation of these components. It should be noted that phytochromes are autophosphorylating protein kinases. Recently, the protein kinase activity of phytochrome A (phyA) has shown to be important for its function in plant light signaling using Avena sativa phyA mutants with reduced or increased kinase activity. In this review, we highlight the function of phyA as a protein kinase to explain the regulation of plant photoresponses by phyA.

Long-Term Survival Analysis of 5619 Total Ankle Arthroplasty and Patient Risk Factors for Failure.

BACKGROUND: Total ankle arthroplasty (TAA) has higher complication and failure rates compared to other surgical joint replacement procedures despite technological advances. This study aimed to find the long-term survivability of the TAA procedure and identify the patient risk factors for failure with one of the largest cohorts of patients in the literature. METHODS: This retrospective cohort study involving cases between 2007 and 2018 analyzed patients who received an index primary TAA procedure in Korea. A total of 5619 cases were included in the final analysis. The TAA failure was defined as either a case with revision arthroplasty or a case with TAA implant removal and arthrodesis performed after primary TAA. RESULTS: During the study period, the 5-year survival rate was 95.4% (95% CI, 94.7-96.1%), and the 10-year survival rate was 91.1% (95% CI, 89.1-93.1%). A younger age (<55 years, adjusted hazard ratio [AHR], 1.725; 55-64 years, AHR, 1.812; p < 0.001 for both), chronic pulmonary disease (AHR, 1.476; p = 0.013), diabetes (AHR, 1.443; p = 0.014), and alcohol abuse (AHR, 1.524; p = 0.032) showed a significantly high odds ratio for primary TAA failure in Cox regression analysis. CONCLUSION: The 10-year TAA survivorship rate was 91.1%. A younger age, chronic pulmonary disease, diabetes, and heavy alcohol consumption are risk factors for TAA.

Mucus-inspired organogel as an efficient absorbent and retention agent for volatile organic compounds.

Nasal mucus plays a key role in the sense of smell by absorbing and transporting chemicals to olfactory receptors. Inspired by the physical properties of mucus that enable it to transport molecules despite its high viscosity, we developed a polymeric organogel with similar viscosity and analyzed its general performance. Through qualitative and quantitative analysis, we confirmed that the matrix viscosity mainly affects the absorption and retention of volatile organic compounds (VOCs) and not their diffusion inside the matrix. Additionally, the vapor pressure of VOCs influences the absorption and retention efficiencies of the matrix. Finally, a detailed understanding of the properties of mucus along with the use of sol-gel transition enabled us to create an efficient VOC absorbent and retention agent.

Microwave-Assisted Dendropanax morbifera Extract for Cosmetic Applications.

Recently, utilizing natural bioactive compounds for active ingredients in cosmetics has become a growing worldwide trend. More and more studies aim to identify the sources of herbal ingredients for applications in the pharmaceutical and cosmetic fields. Additionally, in order to optimize the safety of natural ingredients, choosing an environmentally friendly extraction method also plays an important role. In this work, an eco-friendly extraction technique for Dendropanax morbifera using microwave treatment and microwave-assisted Dendropanax morbifera extract (MA-DME) was investigated. The results indicate that higher yields of MA-DME were obtained than with conventional methods and that D. morbifera's antioxidant properties were enhanced. Moreover, we found that MA-DME exhibited extraordinary antioxidant, anti-aging, and skin-whitening activities. We suggest MA-DME as a potential cosmeceutical ingredient than could be utilized for comprehensive protection of human skin.

Molecular Engineering of Printed Semiconducting Blends to Develop Organic Integrated Circuits: Crystallization, Charge Transport, and Device Application Analyses.

Solution-based printing has contributed to the facile deposition of various types of materials, including the building blocks of printed electronics. In particular, solution-processable organic semiconductors (OSCs) are regarded as one of the most fascinating candidates for the fabrication of printed electronics. Herein, we report electrohydrodynamic (EHD) jet-printed p- and n-type OSCs, namely 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN) and 6,13-bis((triisopropylsilyl)ethynyl)-5,7,12,14-tetraazapentacene (TIPS-TAP), and their use as single-OSC layers and as OSC mixed p-n layers to fabricate solution-processed p-, n-, and ambipolar-type organic field-effect transistors (OFETs). Use of the dragging mode of EHD jet printing, a process driven under a low electrostatic field with a short nozzle-to-substrate distance, was found to provide favorable conditions for growth of TIPS-PEN and TIPS-TAP crystals. In this way, the similar molecular structures of TIPS-PEN and TIPS-TAP yielded a homogeneous solid solution and showed ambipolar transport properties in OFETs. Therefore, the combination of single- and mixed-OSC layers enabled the preparation of various charge-transported devices from unit to integrated devices (NOT, NAND, NOR, and multivalued logic). Therefore, this fabrication technology can be useful for assisting in the production of OSC layers for practical applications in the near future.

The progression of the vertebral body bruise associated with a spinal fracture.

BACKGROUND: Advances in magnetic resonance imaging (MRI) have made it possible to find the vertebral body bruise (VBB), which was not found in computed tomography (CT) after trauma. There has been only one study with adult patients about whether traumatic VBB will cause a collapse of the vertebral body or not. The purpose is to elucidate the progression of VBB in non-osteoporotic adult patients and to identify the possible factors influencing the progression. METHOD: The VBB was defined on MRI as band-like or diffuse zones of high signal intensity on T2-weighted sequences without fracture of the cortex based on CT. The study population with traumatic VBB associated with non-osteoporotic spinal fracture was composed of 15 females and 21 males. The minimal follow-up period was 6 months. The ratio of anterior to posterior heights of the VBB, the ratio of anterior heights of the VBB to the average of those of cranial and caudal adjacent vertebral bodies, the anterior wedge angle of the VBB, and the focal angle around the VBB were compared between the initial and final visits. We evaluated the age of the patients, the C2 plumb line distance, the regional location of VBB, the etiology of VBB, and the treatment methods of the fractures as possible risk factors influencing the progression. RESULTS: There was no difference in the ratios and angles between the initial and final visits. The differences in the ratios and angles between the initial and final visits were not dependent on the possible risk factors. The anterior superior area is the most common in the distribution of VBB. CONCLUSIONS: Unlike compression fractures, the vertebral body with traumatic VBB found in adult patients with non-osteoporotic spinal fractures of AO classification A or B types did not develop collapse. In clinical practice, it is reasonable to diagnose it as a spinal fracture rather than a VBB if the collapse of a possible VBB occurs.

Plant-Derived Nanoscale-Encapsulated Antioxidants for Oral and Topical Uses: A Brief Review.

Several plant-based nanoscale-encapsulated antioxidant compounds (rutin, myricetin, ß-carotene, fisetin, lycopene, quercetin, genkwanin, lutein, resveratrol, eucalyptol, kaempferol, glabridin, pinene, and whole-plant bio-active compounds) are briefly introduced in this paper, along with their characteristics. Antioxidants' bioavailability has become one of the main research topics in bio-nanomedicine. Two low patient compliance drug delivery pathways (namely, the oral and topical delivery routes), are described in detail in this paper, for nanoscale colloidal systems and gel formulations. Both routes and/or formulations seek to improve bioavailability and maximize the drug agents' efficiency. Some well-known compounds have been robustly studied, but many remain elusive. The objective of this review is to discuss recent studies and advantages of nanoscale formulations of plant-derived antioxidant compounds.

Hydroprinting Technology to Transfer Ultrathin, Transparent, and Double-Sided Conductive Nanomembranes for Multiscale 3D Conformal Electronics.

Transparent multiscale 3D conformal electronics using hydroprinting with polyvinyl alcohol (PVA) as a sacrificial layer to transfer networks of silver nanowires (AgNWs) without a carrier layer is developed. However, AgNWs are known to disperse on water surfaces during the transfer process. Therefore, a functional film is developed by simultaneously welding and embedding AgNWs in the PVA through a simple one-step thermal pressing, demonstrating that ultrathin, transparent, and double-sided conductive/patterned nanomembranes with welded AgNWs can float on water without dispersion. The nanomembrane with an excellent figure of merit of 1200, a low sheet resistance of 16.2 Ω sq-1 , and a high transmittance of 98.17% achieves conformal contact with excellent step surface coverage of complex macro- and microstructures because of its nanoscale thickness (54.39 nm) and numerous deformable micro- and nanopores. Furthermore, the double-sided conductive nanomembranes facilitate wiring and layer-by-layer assembly, regardless of the transfer direction of the surface. As a proof-of-concept demonstration, a nanomembrane-based aneurysm sensor is developed. Its high transparency enables coil embolization, and the sensor can measure the pushing force of the coil within an aneurysm in an endovascular simulator. Moreover, this newly developed hydroprinting technology provides a new method for the fabrication of transparent multiscale 3D conformal electronics.

The Influence of Suture-Tape Augmentation on Biological Healing of the Anterior Talofibular Ligament in Chronic Ankle Instability: A Quantitative Analysis Using MRI.

While the effectiveness of suture-tape augmentation for chronic ankle instability has been supported biomechanically and clinically, little information is available regarding biological changes of the lateral ligaments postoperatively. This study aims to quantitatively evaluate ligament regeneration with MRI after suture-tape augmentation. Forty-six patients underwent MRI scan at follow-up of a minimum of 1 year after lateral ligaments augmentation using suture-tape. The signal-to-noise ratio (SNR) and width of anterior talofibular ligament (ATFL) were measured on preoperative and postoperative MRI by 3 researchers. The degree of biological healing of ATFL was analyzed based on the change of SNR and comparison with normal contralateral ankle. Clinical outcomes were evaluated with the Foot and Ankle Outcome Score, Foot and Ankle Ability Measure. Mean Foot and Ankle Outcome Score and Foot and Ankle Ability Measure scores improved significantly from 63.1 to 92.7, and 59.6 to 91.5 points at final follow-up, respectively (p < .001). Mean SNR and width of ATFL were changed insignificantly from 8.24 to 7.96, and 1.88 mm to 2.05 mm at final follow-up, respectively (p = .391, .509). As compared to contralateral side, there were significant differences in both mean SNR and width of the ATFL, respectively (p < .001, p = .0012). Spearman's correlation analysis revealed no significant association between clinical outcomes and degree of biological healing of ATFL based on MRI. Despite significant improvement in patient-reported clinical outcomes, the influence on ligament regeneration of suture-tape augmentation for chronic ankle instability was insignificant. In addition, there was no significant correlation between clinical outcomes and degree of biological healing of the ATFL.

A quantitative evaluation of the individual components contributing to the functional ankle instability in patients with modified Broström procedure.

Residual functional ankle instability regardless of the restoration of mechanical stability after the lateral ligament repair or reconstruction can cause recurrent sprain. The purpose of this study was to identify the sequential changes of joint-position sense, peroneal strength, postural control, and functional performance ability after the modified Broström procedure (MBP) for chronic ankle instability. A total of 46 patients (46 ankles) underwent the MBP for chronic ankle instability were eligible for this study and were followed for 1 year postoperatively. The changes of joint-position sense and peroneal strength were periodically evaluated with an isokinetic dynamometer. Postural control ability was evaluated using a one-leg stance test with eyes closed. The functional performance ability examination comprised a one-leg hop test, a 6-meter hop test, and a cross 3-meter hop test. The error in joint-position sense significantly improved from a mean 4.3º to 2.8º (p < .001). Peak torque for eversion significantly improved from a mean 18.2 Nm to 21.2 Nm (p = .024). Balance retention time significantly improved from a mean 4.7 seconds to 6.4 seconds (p < .001). Among the functional performance tests, only the one-leg hop test showed a significant improvement postoperatively (p = .031). At 1 year postoperatively, the recovery ratios compared to the unaffected ankle were 67.9% in joint-position sense (p < .001), 86.9% in peroneal strength (p = .012), and 74.4% in postural control (p < .001) with significant side-to-side differences. Although joint-position sense, peroneal strength, postural control, and functional performance ability were significantly improved after the MBP, recovery ratios compared to the unaffected ankle were insufficient up to 1 year postoperatively.

High-Resolution and Facile Patterning of Silver Nanowire Electrodes by Solvent-Free Photolithographic Technique Using UV-Curable Pressure Sensitive Adhesive Film.

Patterning of silver nanowires (AgNWs) used in fabricating flexible and transparent electrodes (FTEs) is essential for constructing a variety of optoelectronic devices. However, patterning AgNW electrodes using a simple, inexpensive, high-resolution, designable, and scalable process remains a challenge. Therefore, herein a novel solvent-free photolithographic technique using a UV-curable pressure sensitive adhesive (PSA) film for patterning AgNWs is introduced. The UV-curable PSA film can be selectively patterned by photopolymerization under UV exposure through a photomask. The AgNWs embedded in the non-photocured adhesive areas of the film are firmly held by a crosslinked network of photocurable resin when the patterned film is attached to the AgNW-coated substrate and additionally irradiated by UV light. After peeling off the film, the positive pattern of AgNW electrodes remains on the substrate, while the negative pattern is transferred to the film. This solvent-free photolithographic technique, which does not use toxic solvents, provides superior pattern features, such as fine line widths and spacings, sharp line edges, and low roughness. Therefore, the developed technique could be successfully applied in the development of flexible and transparent optoelectronic devices, such as a self-cleaning electro-wetting-on-dielectric (EWOD) devices, transparent heaters, and FTEs.

Electrohydrodynamic-Jet-Printed Cinnamate-Fluorinated Cross-Linked Polymeric Dielectrics for Flexible and Electrically Stable Operating Organic Thin-Film Transistors and Integrated Devices.

Herein, printable polymer series containing different portions of cinnamate and perfluorinated phenyl functionalities, namely, polyperfluorostyrene-co-poly(vinylbenzyl cinnamates) (PFS-co-PVBCi (x:y)) copolymers, were synthesized and applied as gate dielectrics for organic thin-film transistors (OTFTs). The polymeric dielectrics were successfully printed via electrostatic force-assisted dispensing mode of electrohydrodynamic jet printing. The dielectric characteristics of the printed polymers, such as surface energy, dielectric constant, leakage current, atomic depth profiles, and deposited semiconducting layer characteristics, were clearly identified. In particular, the difference in driving stability of OTFTs according to the type of polymer was analyzed in detail and a possible mechanism was proposed. Results suggested that PFS-co-PVBCi (3:7) led to optimized consequences, yielding an almost negligible Vth shift under continuous bias stress. Through this, we successfully implemented flexible OTFT and logic devices using printed PFS-co-PVBCi (3:7) dielectrics with stable operation properties. Therefore, we believe that this study will facilitate the printing and synthesis of polymer dielectrics to produce printed and flexible OTFTs.

Enhancement of Steel Sandwich Sheet Adhesion Using Mechanical Interlocking Structures Formed by Electrochemical Etching.

Steel sandwich sheets (steel-polymer-steel), which are composed of lightweight polymers bonded on both sides with rigid steel sheets, have recently been developed as functional lightweight materials. In this study, a steel sandwich sheet (electrogalvanized (EG) steel sheet-polypropylene (PP)-EG steel sheet) with improved normal adhesion is fabricated without adhesives. Instead, adhesion is achieved via mechanical interlocking between the etched EG steel sheets and PP. Hierarchical structures were formed on the EG steel sheet surface by electrochemical etching to attain effective mechanical interlocking for improving normal adhesion without any adhesives. In the case of the EG steel sheet etched at 6 V for 7 s, a high fraction (∼35%) of holes (size: <1 µm2) with nanoscale scalloped structures was formed on the EG steel sheet surface. The normal adhesion test result of the fabricated steel sandwich sheet showed that the adhesion strength increased from virtually 0 (bare) to 559.6 kPa as a result of mechanical interlocking. The results of the focused ion beam-scanning electron microscopy and energy-dispersive spectrometry analyses confirmed the cohesive failure of PP resulting from the successful mechanical interlocking of PP with the holes formed on the etched EG steel sheet. To examine the effect of hierarchical structures on the normal adhesion of the steel sandwich sheet, finite element analysis was implemented.