Bioinspired shape shifting of liquid-infused ribbed sheets.

The recent emergence of stimuli-responsive, shape-shifting materials offers promising applications in fields as different as soft robotics, aeronautics, or biomedical engineering. Targeted shapes or movements are achieved from the advantageous coupling between some stimulus and various materials such as liquid crystalline elastomers, magnetically responsive soft materials, swelling hydrogels, etc. However, despite the large variety of strategies, they are strongly material dependent and do not offer the possibility to choose between reversible and irreversible transformations. Here, we introduce a strategy applicable to a wide range of materials yielding systematically reversible or irreversible shape transformations of soft ribbed sheets with precise control over the local curvature. Our approach-inspired by the spore-releasing mechanism of the fern sporangium-relies on the capillary deformation of an architected elastic sheet impregnated by an evaporating liquid. We develop an analytical model combining sheet geometry, material stiffness, and capillary forces to rationalize the onset of such deformations and develop a geometric procedure to inverse program target shapes requiring fine control over the curvature gradient. We finally demonstrate the potential irreversibility of the transformation by UV-curing a photosensitive evaporating solution and show that the obtained shells exhibit enhanced mechanical stiffness.

Segmenting and Predicting Musical Phrase Structure Exploits Neural Gain Modulation and Phase Precession.

Music, like spoken language, is often characterized by hierarchically organized structure. Previous experiments have shown neural tracking of notes and beats, but little work touches on the more abstract question: how does the brain establish high-level musical structures in real time? We presented Bach chorales to participants (20 females and 9 males) undergoing electroencephalogram (EEG) recording to investigate how the brain tracks musical phrases. We removed the main temporal cues to phrasal structures, so that listeners could only rely on harmonic information to parse a continuous musical stream. Phrasal structures were disrupted by locally or globally reversing the harmonic progression, so that our observations on the original music could be controlled and compared. We first replicated the findings on neural tracking of musical notes and beats, substantiating the positive correlation between musical training and neural tracking. Critically, we discovered a neural signature in the frequency range ∼0.1 Hz (modulations of EEG power) that reliably tracks musical phrasal structure. Next, we developed an approach to quantify the phrasal phase precession of the EEG power, revealing that phrase tracking is indeed an operation of active segmentation involving predictive processes. We demonstrate that the brain establishes complex musical structures online over long timescales (>5 s) and actively segments continuous music streams in a manner comparable to language processing. These two neural signatures, phrase tracking and phrasal phase precession, provide new conceptual and technical tools to study the processes underpinning high-level structure building using noninvasive recording techniques.

PtPd Atomic Layer Shelled PdCu Hollow Nanoparticles on Partially Unzipped Carbon Nanotubes for Breaking the Activity-Stability Trade-Off toward the Hydrogen Oxidation Reaction in Alkaline Media.

Developing highly active yet stable catalysts for the hydrogen oxidation reaction (HOR) in alkaline media remains a significant challenge. Herein, we designed a novel catalyst of atomic PtPd-layer shelled ultrasmall PdCu hollow nanoparticles (HPdCu NPs) on partially unzipped carbon nanotubes (PtPd@HPdCu/W-CNTs), which can achieve a high mass activity, 5 times that of the benchmark Pt/C, and show exceptional stability with negligible decay after 20,000 cycles of accelerated degradation test. The atomically thin PtPd shell serves as the primary active site for the HOR and a protective layer that prevents Cu leaching. Additionally, the HPdCu substrate not only tunes the adsorption properties of the PtPd layer but also prevents corrosive Pt from reaching the interface between NPs and the carbon support, thereby mitigating carbon corrosion. This work introduces a new strategy that leverages the distinct advantages of multiple components to address the challenges associated with slow kinetics and poor durability toward the HOR.

Synergistic Biofilter Tube for Promoting Scarless Tendon Regeneration.

Inspired by the imbalance between extrinsic and intrinsic tendon healing, this study fabricated a new biofilter scaffold with a hierarchical structure based on a melt electrowriting technique. The outer multilayered fibrous structure with connected porous characteristics provides a novel passageway for vascularization and isolates the penetration of scar fibers, which can be referred to as a biofilter process. In vitro experiments found that the porous architecture in the outer layer can effectively prevent cell infiltration, whereas the aligned fibers in the inner layer can promote cell recruitment and growth, as well as the expression of tendon-associated proteins in a simulated friction condition. It was shown in vivo that the biofilter process could promote tendon healing and reduce scar invasion. Herein, this novel strategy indicates great potential to design new biomaterials for balancing extrinsic and intrinsic healing and realizing scarless tendon healing.

One-Step Electrochemically Prepared Bionic Hierarchical Nickel Black@Graphene Composite Membrane for Desalination by Solar-Thermal Energy Conversion.

Ingenious microstructure construction and appropriate composition selection are effective strategies for achieving enhanced performance of photothermal materials. Herein, a broccoli-like hierarchical nickel black@graphene (Ni@Gr) membrane for solar-driven desalination was prepared by a one-step electrochemical method, which was carried out simultaneously with the electrochemical exfoliation of graphene and the co-deposition of Ni@Gr material. The bionic hierarchical structure and the chemical composition of the Ni@Gr membrane increased the sunlight absorption (90.36%) by the light-trapping effect and the introduction of graphene. The Ni@Gr membrane achieved high evaporation rates of 2.05 and 1.16 kg m-2 h-1 under simulated (1 sun) and outdoor sunlight conditions, respectively. The superhydrophilicity and the hierarchical structure of the Ni@Gr membrane jointly reduced the evaporation enthalpy (1343.6 kJ/kg), which was beneficial to break the theoretical limit of the evaporation rate (1.47 kg m-2 h-1). This work encourages the application of bionic metal-carbon composite photothermal materials in solar water evaporation.

Ion-Exchange Enabled Dual-Functional Swarms with Reconfigurability and Magnetic Controllability.

In nature, many organisms are capable of self-organizing into collective groups through local communications to perform complex tasks that individuals cannot complete. To date, the reported artificial microswarms either rely on toxic chemical reactions for communication or lack the hierarchical controllability and functionality, which is unfavorable for practical applications. To this end, this exploits the ion-exchange reaction enabled hierarchical swarm composed of cationic ion exchange resin and magnetic microspheres of internal information exchange. The swarm is reconfigurable under magnetic fields, generating ordered structures of controllable mobilities and even reversed hierarchy, able to navigate in confined and complex environments. Moreover, the swarm shows interesting communications among each other, such as merging, splitting, and member exchange, forming multi-leader groups, living crystals, and complex vortices. Furthermore, the swarm functions as a dual-functional microreactor, which can load, transport, and release drugs in a pH-enhanced manner, as well as effectively degrade antibiotics via light-enhanced Fenton-like reaction in polluted water. The organized structure of the swarm greatly improves the drug loading/transport efficiency and the local concentration of catalysts for fast pollutant removal. This design lays the foundation for the design of dual-functional micro/nanorobots for intelligent drug delivery and advanced environmental remediation.

Constructing Porous Energetic Spherulites via Solvation-Growth Coupling for Enhanced Combustion.

The fabrication of materials with hierarchical structures has garnered great interest, owing to the potential for significantly enhancing their functions. Herein, a strategy of coupling molecular solvation and crystal growth is presented to fabricate porous spherulites of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), an important energetic material. With the addition of polyvinylpyrrolidone in the antisolvent crystallization, the metastable solvate of CL-20 is formed and grows spherulitically, and spontaneously desolvates to obtain the porous spherulite when filtration, in which the characteristic peak of the nitro group of CL-20 shifts detected by the in situ micro-confocal Raman spectroscopy. The effect of polyvinylpyrrolidone is thought to induce the solvation of CL-20, confirmed by density functional theory calculations, meanwhile acting on the (020) face of CL-20 to trigger spherulitic growth, demonstrated through infrared spectroscopy and Rietveld refinement of powder X-ray diffraction. Moreover, compared to common CL-20 crystals, porous spherulites exhibit enhanced combustion with increases of 6.24% in peak pressure, 40.21% in pressurization rate, and 9.63% in pressure duration effect, indicating the capability of hierarchical structures to boost the energy release of energetic crystals. This work demonstrates a new route via solvation-growth coupling to construct hierarchical structures for organic crystals and provides insight into the structure-property relations for material design.

Regulation of Charge Transfer Pathway in Ag-ZnIn2S4 Nanowires for Visible Photodynamic Therapy on Candida Albicans Infections.

Photodynamic therapy (PDT) is receiving extensive attention as an antimicrobial strategy that does not cause drug resistance by reactive oxygen species (ROS). Herein, hierarchical Ag-ZnIn2S4 (Ag-ZIS) core-shell nanowires are synthesized by in situ Metal-Organic Framework derived method for efficient PDT of Candida albicans (C. albicans). The core-shell structure enables spatial synergy strategy to regulate the charge transfer pathway under visible light excitation, in which the Ag nanowires are like the highway for the photogenerated electrons. The enhanced charge carrier separation efficiency greatly increased the chances for the generation of ROS. As expected, the optimized Ag-ZIS nanowires exhibit excellent performance for inactivation of C. albicans under visible light irradiation (λ ≥ 420 nm, 15 min), and the effective sterilization concentration is as high as 107CFU mL-1. Moreover, in vivo infection experiments suggested that the PDT effect of Ag-ZIS nanowires on the mouse wound healing is better than that of the clinical Ketoconazole drug. The PDT antifungal mechanism of Ag-ZIS nanowires is also investigated, and superoxide anion is found to be the predominant active species to causes C. albicans damage. This work provides a new perspective for designing novel interface structures to regulate charge transfer to achieve efficient PDT antifungal therapy.

Ultrafast Bi-Directional Bending Moisture-Responsive Soft Actuators through Superfine Silk Rod Modified Bio-Mimicking Hierarchical Layered Structure.

Development of stimulus-responsive materials is crucial for novel soft actuators. Among these actuators, the moisture-responsive actuators are known for their accessibility, eco-friendliness, and robust regenerative attributes. A major challenge of moisture-responsive soft actuators (MRSAs) is achieving significant bending curvature within short response times. Many plants naturally perform large deformation through a layered hierarchical structure in response to moisture stimuli. Drawing inspiration from the bionic structure of Delosperma nakurense (D. nakurense) seed capsule, here the fabrication of an ultrafast bi-directional bending MRSAs is reported. Combining a superfine silk fibroin rod (SFR) modified graphene oxide (GO) moisture-responsive layer with a moisture-inert layer of reduced graphene oxide (RGO), this actuator demonstrated large bi-directional bending deformation (-4.06 ± 0.09 to 10.44 ± 0.00 cm-1) and ultrafast bending rates (7.06 cm-1 s-1). The high deformation rate is achieved by incorporating the SFR into the moisture-responsive layers, facilitating rapid water transmission within the interlayer structure. The complex yet predictable deformations of this actuator are demonstrated that can be utilized in smart switch, robotic arms, and walking device. The proposed SFR modification method is simple and versatile, enhancing the functionality of hierarchical layered actuators. It holds the potential to advance intelligent soft robots for application in confined environments.

Kiwi-Inspired Rational Nanoarchitecture with Intensified and Discrete Magneto-Fluorescent Functionalities for Ultrasensitive Point-of-Care Immunoassay.

Fluorescent lateral flow immunoassays (FLFIA) is a well-established rapid detection technique for quantitative analysis. However, achieving accurate analysis of biomarkers at the pg mL-1 level using FLFIA still poses challenges. Herein, an ultrasensitive FLFIA platform is reported utilizing a kiwi-type magneto-fluorescent silica nanohybrid (designated as MFS) that serves as both a target-enrichment substrate and an optical signal enhancement label. The spatially-layered architecture comprises a Fe3O4 core, an endocarp-fibers like dendritic mesoporous silica, seed-like quantum dots, and a kiwi-flesh like silica matrix. The MFS demonstrates heightened fluorescence brightness, swift magnetic response, excellent size uniformity, and dispersibility in water. Through liquid-phase capturing and fluorescence-enhanced signal amplification, as well as magnetic-enrichment sample amplification and magnetic-separation noise reduction, the MFS-based FLFIA is successfully applied to the detection of cardiac troponin I that achieved a limit of detection at 8.4 pg mL-1, tens of times lower than those of previously published fluorescent and colorimetric lateral flow immunoassays. This work offers insights into the strategic design of magneto-fluorescent synergetic signal amplification on LFIA platform and underscores their prospects in high-sensitive rapid and on-site diagnosis of biomarkers.

Language-like efficiency and structure in house finch song.

Communication needs to be complex enough to be functional while minimizing learning and production costs. Recent work suggests that the vocalizations and gestures of some songbirds, cetaceans and great apes may conform to linguistic laws that reflect this trade-off between efficiency and complexity. In studies of non-human communication, though, clustering signals into types cannot be done a priori, and decisions about the appropriate grain of analysis may affect statistical signals in the data. The aim of this study was to assess the evidence for language-like efficiency and structure in house finch (Haemorhous mexicanus) song across three levels of granularity in syllable clustering. The results show strong evidence for Zipf's rank-frequency law, Zipf's law of abbreviation and Menzerath's law. Additional analyses show that house finch songs have small-world structure, thought to reflect systematic structure in syntax, and the mutual information decay of sequences is consistent with a combination of Markovian and hierarchical processes. These statistical patterns are robust across three levels of granularity in syllable clustering, pointing to a limited form of scale invariance. In sum, it appears that house finch song has been shaped by pressure for efficiency, possibly to offset the costs of female preferences for complexity.

Utilization of reproductive health services among undergraduate regular class students in Assosa University, BGRS: a comparison among three varieties of multilevel binary logistic regression models.

INTRODUCTION: Reproductive health service (RHS) helps for people to have a delighted and safe sex through their life journey. It enables especially for women to go safely through pregnancy and childbirth and provide couples with the best chance of having a healthy infant. Therefore, this study aimed to identify the significant determinants of RHS utilization among undergraduate regular class students in Assosa University by using advanced methodology. METHODS: We used cross-sectional study design to collect RHS data from 362 students in Assosa University from 5 to 16, may 2021. These students were selected using stratified random sampling technique. We also used cross-tabulation to summarize the extents of RHS utilization across all predictors in terms of percentage and three varieties of multilevel binary logistic regression model to model the determinants of RHS. RESULTS: 42.27% of undergraduate regular class students in Assosa University utilize at least one type of RHS during their time at Assosa University whereas, 57.73% of undergraduate regular class students in this University are not utilized it. Among three varieties of multilevel binary logistic regression models, the random slopes two-level model was selected as a best fitted model for the datasets. At 5% level of significance, awareness about RHS, gender, preference of service fees and student's monthly average income were significant predictor variables in this model. In addition, the covariates; age, gender and preference of service fees have a significant random effects on utilization of RHS across all colleges/school. CONCLUSION: Students who; preferred service fee as usual rate, have awareness about RHS, are females and have high monthly average income were more likely to utilize RHS. RHS utilization among undergraduate regular students in Assosa University is likely to increase more effectively with interventions that address these factors.

HDPose: Post-Hierarchical Diffusion with Conditioning for 3D Human Pose Estimation.

Recently, monocular 3D human pose estimation (HPE) methods were used to accurately predict 3D pose by solving the ill-pose problem caused by 3D-2D projection. However, monocular 3D HPE still remains challenging owing to the inherent depth ambiguity and occlusions. To address this issue, previous studies have proposed diffusion model-based approaches (DDPM) that learn to reconstruct a correct 3D pose from a noisy initial 3D pose. In addition, these approaches use 2D keypoints or context encoders that encode spatial and temporal information to inform the model. However, they often fall short of achieving peak performance, or require an extended period to converge to the target pose. In this paper, we proposed HDPose, which can converge rapidly and predict 3D poses accurately. Our approach aggregated spatial and temporal information from the condition into a denoising model in a hierarchical structure. We observed that the post-hierarchical structure achieved the best performance among various condition structures. Further, we evaluated our model on the widely used Human3.6M and MPI-INF-3DHP datasets. The proposed model demonstrated competitive performance with state-of-the-art models, achieving high accuracy with faster convergence while being considerably more lightweight.

Designing an Effective and Scalable UV-Protective Cooling Textile with Nanoporous Fibers.

Although radiative cooling concepts guarantee reduction of air conditioning energy consumption by maximizing the scattering of solar radiation and dissipation of thermal radiation of a human body or building, large-scale implementation is challenging due to the need of radical adaptation in manufacturing processes, materials, and design. Here, we introduce an extremely thin layer of nanoporous microfibers without any additional materials or post-treatments. The optical and thermal effectiveness of porous fibers are presented to report a nondisruptive method of preventing the transmission of energy-intensive radiation such as ultraviolet radiation (UV) through textiles. Results show ∼1.4 °C cooling by adding 1 g/m2 (GSM) of porous fibers on a 160 GSM cotton t-shirt, and 91% of UV was prevented with 7.5 GSM of a porous fiber mat. This minimalistic additive approach would widen the scope of optical and radiative cooling research and accelerate both functional and sustainable materials research to be more accessible.

Hierarchically Structured Nanoporous Palladium with Ordered/Disordered Channels for Ultrahigh and Fast Strain.

Metallic actuators have increasingly shown the potential to replace conventional piezoelectric ceramics and conducting polymers. However, it is still a great challenge to achieve strain amplitudes over 4% while maintaining fast strain responses. Herein, we fabricated bulk nanoporous palladium (NP-Pd) with microsheet-array-like hierarchically nanoporous (MAHNP) structure by dealloying a eutectic Al-Pd precursor. The hierarchical structure consists of array-like microsized channels/sheets and disordered nanosized networks. The locally ordered channels play a critical role in fast mass transport while nanoligaments accumulate a large surface area for hydrogen adsorption/absorption and desorption. Therefore, the MAHNP-Pd not only obtains a fast strain rate with the maximum value close to 1 × 10-4 s-1 but also exhibits an ultrahigh strain amplitude of 4.68%, exceeding all reported values for bulk electrochemical metallic actuators to date. Additionally, the superiority of the MAHNP structure is demonstrated in transport kinetics as benchmarked with the scenario of unimodal NP-Pd.

Highly Efficient All-3D-Printed Electrolyzer toward Ultrastable Water Electrolysis.

The practical application of electrochemical water splitting has been plagued by the sluggish kinetics of bubble generation and the slow escape of bubbles which block reaction surfaces at high current densities. Here, 3D-printed Ni (3DP Ni) electrodes with a rationally designed periodic structure and surface chemistry are reported, where the macroscopic ordered pores allow fast bubble evolution and emission, while the microporosity ensures a high electrochemically active surface area (ECSA). When they are further loaded with MoNi4 and NiFe layered double hydroxide active materials, the 3D electrodes deliver 500 mA cm-2 at an overpotential of 104 mV for the hydrogen evolution reaction (HER) and 310 mV for the oxygen evolution reaction (OER), respectively. An all-3D-printed alkaline electrolyzer (including electrodes, membrane, and cell) delivers 500 mA cm-2 at a remarkable voltage of 1.63 V with no noticeable performance decay after 1000 h. Such a tailored bubble trajectory demonstrates feasible solutions for future large-scale clean energy production.

Structure-function coupling reveals the brain hierarchical structure dysfunction in Alzheimer's disease: A multicenter study.

BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative condition characterized by cognitive decline. To date, the specific dysfunction in the brain's hierarchical structure in AD remains unclear. METHODS: We introduced the structural decoupling index (SDI), based on a multi-site data set comprising functional and diffusion-weighted magnetic resonance imaging data from 793 subjects, to assess their brain hierarchy. RESULTS: Compared to normal controls (NCs), individuals with AD exhibited increased SDI within the posterior superior temporal sulcus, insular gyrus, precuneus, hippocampus, amygdala, postcentral gyrus, and cingulate gyrus; meanwhile, the patients with AD demonstrated decreased SDI in the frontal lobe. The SDI in those regions also showed a significant correlation with cognitive ability. Moreover, the SDI was a robust AD neuroimaging biomarker capable of accurately distinguishing diagnostic status (area under the curve [AUC] = 0.86). DISCUSSION: Our findings revealed the dysfunction of the brain's hierarchical structure in AD. Furthermore, the SDI could serve as a promising neuroimaging biomarker for AD. HIGHLIGHTS: This study utilized multi-center, multi-modal data from East Asian populations. We found an increased spatial gradient of the structure decoupling index (SDI) from sensory-motor to higher-order cognitive regions. Changes in SDI are associated with energy metabolism and mitochondria. SDI can identify Alzheimer's disease (AD) and further uncover the disease mechanisms of AD.

Synthesis of Pd-Doped SnO2 and Flower-like Hierarchical Structures for Efficient and Rapid Detection of Ethanolamine.

In this study, we successfully synthesized a Pd-doped SnO2 (Pd-SnO2) material with a flower-like hierarchical structure using the solvothermal method. The material's structural proper-ties were characterized employing techniques such as XRD, XPS, FESEM and HRTEM. A gas sensor fabricated from the 2.0 mol% Pd-SnO2 material demonstrated exceptional sensitivity (Ra/Rg = 106) to 100 ppm ethanolamine at an operating temperature of 150 °C, with rapid response/recovery times of 10 s and 12 s, respectively, along with excellent linearity, selectivity, and stability, and a detection limit down to 1 ppm. The superior gas-sensing performance is attributed to the distinctive flower-like hierarchical architecture of the Pd-SnO2 and the lattice distortions introduced by Pd doping, which substantially boost the material's sensing characteristics. Further analysis using density functional theory (DFT) has revealed that within the Pd-SnO2 system, Sn exhibits strong affinities for O and N, leading to high adsorption energies for ethanolamine, thus enhancing the system's selectivity and sensitivity to ethanolamine gas. This research introduces a novel approach for the efficient and rapid detection of ethanolamine gas.

Hierarchically Structured Graphene Aerogel Supported Nickel-Cobalt Oxide Nanowires as an Efficient Electrocatalyst for Oxygen Evolution Reaction.

The rational design of a heterostructure electrocatalyst is an attractive strategy to produce hydrogen energy by electrochemical water splitting. Herein, we have constructed hierarchically structured architectures by immobilizing nickel-cobalt oxide nanowires on/beneath the surface of reduced graphene aerogels (NiCoO2/rGAs) through solvent-thermal and activation treatments. The morphological structure of NiCoO2/rGAs was characterized by microscopic analysis, and the porous structure not only accelerates the electrolyte ion diffusion but also prevents the agglomeration of NiCoO2 nanowires, which is favorable to expose the large surface area and active sites. As further confirmed by the spectroscopic analysis, the tuned surface chemical state can boost the catalytic active sites to show the improved oxygen evolution reaction performance in alkaline electrolytes. Due to the synergistic effect of morphology and composition effect, NiCoO2/rGAs show the overpotential of 258 mV at the current density of 10 mA cm-2. Meanwhile, the small values of the Tafel slope and charge transfer resistance imply that NiCoO2/rGAs own fast kinetic behavior during the OER test. The overlap of CV curves at the initial and 1001st cycles and almost no change in current density after the chronoamperometric (CA) test for 10 h confirm that NiCoO2/rGAs own exceptional catalytic stability in a 1 M KOH electrolyte. This work provides a promising way to fabricate the hierarchically structured nanomaterials as efficient electrocatalysts for hydrogen production.

Jellyfish-inspired Polyurea Ionogel with Mechanical Robustness, Self-Healing, and Fluorescence Enabled by Hyperbranched Cluster Aggregates.

Ionogels are promising for soft iontronics, with their network structure playing a pivotal role in determining their performance and potential applications. However, simultaneously achieving mechanical toughness, low hysteresis, self-healing, and fluorescence using existing network structures is challenging. Drawing inspiration from jellyfish, we propose a novel hierarchical crosslinking network structure design for in situ formation of hyperbranched cluster aggregates (HCA) to fabricate polyurea ionogels to overcome these challenges. Leveraging the disparate reactivity of isocyanate groups, we induce the in situ formation of HCA through competing reactions, enhancing toughness and imparting the clustering-triggered emission of ionogel. This synergy between supramolecular interactions in the network and plasticizing effect in ionic liquid leads to reduced hysteresis of the ionogel. Furthermore, the incorporation of NCO-terminated prepolymer with dynamic oxime-urethane bonds (NPU) enables self-healing and enhances stretchability. Our investigations highlight the significant influence of HCA on ionogel performance, showcasing mechanical robustness including high strength (3.5 MPa), exceptional toughness (5.5 MJ m-3), resistance to puncture, and low hysteresis, self-healing, as well as fluorescence, surpassing conventional dynamic crosslinking approaches. This network design strategy is versatile and can meet the various demands of flexible electronics applications.