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International audience; This article proposes three new decompositions of inequality measures, drawn from the framework of cooperative game theory. It allows the impact of players' interactions, rather than players' contributions to inequality, to be taken into consideration. These innovative approaches are especially suited for the study of income inequality when the income has a hierarchical structure: the income is composed of several primary sources, with the particularity that each of them is also composed of secondary sources. We revisit the Shapley-Owen value that quantifies the importance of each of these secondary sources in the overall income inequality. Our main contribution is to decompose this importance into two parts: the pure marginal contribution of the considered source and a weighted sum of pairwise interactions. We then provide an axiomatic characterization of each additive interaction decomposable (AID) coalitional value considered in this paper. We give an application of these decompositions in the context of inequality theory.

Hierarchically structured polymeric fibers, composed of structural nanoscale motifs that assemble into a microscale fiber are frequently found in natural fibers including cellulose and silk. The creation of synthetic fibers with nano-to-microscale hierarchical structures represents a promising avenue for the development of novel fabrics with distinctive physical, chemical, and mechanical characteristics. In this work, we introduce a novel approach for creating polyamine-based core–sheath microfibers with controlled hierarchical architectures. This approach involves a polymerization-induced spontaneous phase separation and subsequent chemical fixation. Through the use of various polyamines, the phase separation process can be manipulated to produce fibers with diverse porous core architectures, ranging from densely packed nanospheres to segmented “bamboo-stem” morphology. Moreover, the nitrogen-rich surface of the core enables both the chemisorption of heavy metals and the physisorption of proteins and enzymes. Our method offers a new set of tools for the production of polymeric fibers with novel hierarchical morphologies, which has a high potential for a wide range of applications such as filtering, separation, and catalysis.

The concept of “complexity” is considered in relation to radiation processes in condensed matter. It is shown that a combination of such properties as nanoscale, fractality, low dimension, chirality, and hierarchy in combination with high nonequilibrium create conditions for the manifestation of unusual “emergent” radiation effects (radiation synergetics, great dose reduction of threshold radiation effects, etc.). Examples of radiation effects in living and inanimate systems, interpreted within the framework of the concept of “complexity”, are presented. An overview of both previously obtained and new results is presented. © 2022, Pleiades Publishing, Ltd. Russian Foundation for Basic Research, РФФИ: 21-12-00392 This work was supported by the Russian Foundation for Basic Research, project no. 21-12-00392.

The hydrothermal synthesis of nickel oxide in the presence of triethanolamine was studied. Furthermore, the relationship between the synthesis conditions, thermal behavior, crystal structure features, phase composition and microstructure of semi-products, and the target oxide nanopowders was established. The thermal behavior of the semi-products was studied using a simultaneous thermal analysis (in particular, using one that involved thermogravimetric analysis and differential scanning calorimetry, TGA/DSC). An X-ray diffraction (XRD) analysis revealed that varying the triethanolamine and nickel chloride concentration in the reaction system can govern the formation of α- and β-Ni(OH)2-based semi-products that contain Ni(HCO3)2 or Ni2(CO3)(OH)2 as additional components. The set of functional groups in the powders was determined using a Fourier-transform infrared (FTIR) spectroscopy analysis. Using microextrusion printing, a composite NiO—(CeO2)0.80(Sm2O3)0.20 anode film was fabricated. Using XRD, scanning electron microscopy (SEM), and atomic force microscopy (AFM) analyses, it was demonstrated that the crystal structure, dispersity, and microstructure character of the obtained material correspond to the initial nanopowders. Using Kelvin probe force microscopy (KPFM) and scanning capacitance microscopy (SCM), the local electrophysical properties of the printed composite film were examined. The value of its conductivity was evaluated using the four-probe method on a direct current in the temperature range of 300–650 °C. The activation energy for the 500–650 °C region, which is of most interest in the context of intermediate-temperature SOFCs working temperatures, has been estimated.

Fibrin-based hydrogels are used as scaffolds in tissue engineering and regenerative medicine due to their biocompatibility, low cell toxicity, autologous production, and relevance for wound healing and clot formation. The availability of fibrinogen as well as its unique mechanical behavior exhibiting nonlinear elasticity makes it suitable for the fabrication of hydrogels. However, the broad application of fibrin hydrogels in biomaterials still faces challenges in terms of gel shrinkage and degradation processes. This can be addressed through the modulation of the hydrogels'r chemical and mechanical properties. In the present work, it is demonstrated that fibrin-based hydrogels with adjustable mechanical properties and controllable degradation profiles can be fabricated through the addition of fibrin-binding peptides. The cyclic peptide X2CXYYGTCLX (Tn7) is used, binding to fibrin by noncovalent supramolecular interactions. These new hydrogels exhibit no toxicity and reduced degradation rate at the same time supporting cell proliferation. Tn7 peptides significantly increase the Young's Modulus and mechanical stiffness as well as fibrin fiber thickness and inter-fiber crosslinking in hydrogels. In conclusion, hydrogels with optimized mechanical properties and controllable degradation profiles that can be advantageous for further approaches in tissue regeneration, cell-based therapies, or clinical treatment options are produced.

Directed self-assembly of block copolymers is evolving toward applications that are more defect-tolerant but still require high morphological control and could benefit from simple, inexpensive fabrication processes. Previously, we demonstrated that simply casting ultra-thin block copolymer films on topographically defined substrates leads to hierarchical structures with dual patterns in a controlled manner and unraveled the dependence of the local morphology on the topographic feature dimensions. In this article, we discuss the extreme of the ultraconfined thickness regime at the border of film dewetting. Additional non-bulk morphologies are observed at this extreme, which further elaborate the arsenal of dual patterns that could be obtained in coexistence with full placement control. It is shown that as the thickness confinement approaches its limit, lateral confinement imposed by the width of the plateaus becomes a critical factor influencing the local morphology.

Biological materials such as nacre have evolved microstructural design principles that result in outstanding mechanical properties. While nacre's design concepts have led to bio-inspired materials with enhanced fracture toughness, the microstructural features underlying the remarkable damping properties of this biological material have not yet been fully explored in synthetic composites. Here, we study the damping behavior of nacre-like composites containing mineral bridges and platelet asperities as nanoscale structural features within its brick-and-mortar architecture. Dynamic mechanical analysis was performed to experimentally elucidate the role of these features on the damping response of the nacre-like composites. By enhancing stress transfer between platelets and at the brick/mortar interface, mineral bridges and nano-asperities were found to improve the damping performance of the composite to levels that surpass many biological and man-made materials. Surprisingly, the improved properties are achieved without reaching the perfect organization of the biological counterparts. Our nacre-like composites display a loss modulus 2.4-fold higher than natural nacre and 1.4-fold more than highly dissipative natural fiber composites. These findings shed light on the role of nanoscale structural features on the dynamic mechanical properties of nacre and offer design concepts for the manufacturing of bio-inspired composites for high-performance damping applications., Proceedings of the National Academy of Sciences of the United States of America, 119 (31), ISSN:0027-8424, ISSN:1091-6490

Hierarchy provides unique opportunities for the design of advanced materials with superior properties that arise from architecture, rather than from constitutive material response. Contrary to the quasi-static regime, where the potential of hierarchy has been largely explored, its role in vibration mitigation and wave manipulation remains elusive. So far, the majority of the studies concerning hierarchical elastic metamaterials have proposed a self-similar repetition of a specific unit cell at multiple scale levels, leading to the activation of the same bandgap mechanism at different frequencies. On the contrary, here, we show that by designing non self-similar hierarchical geometries allows us to create periodic structures supporting multiple, highly attenuative and broadband bandgaps involving (independently or simultaneously) different scattering mechanisms, namely, Bragg scattering, local resonance and/or inertial amplification, at different frequencies. The type of band gap mechanism is identified and discussed by examining the vibrational mode shapes and the imaginary component of the wavenumber in the dispersion diagram of the unit cell. We also experimentally confirm this by performing measurements in the lowest frequency regime on a 3D printed structure. Hierarchical design strategies may find application in vibration mitigation for civil, aerospace and mechanical engineering., International Journal of Mechanical Sciences, 241, ISSN:0020-7403

In this study, the wetting behavior of microstructured polyethylene terephthalate (PET) foils for polar and nonpolar liquids produced by plate-to-plate hot embossing is investigated. For the embossing step, stainless steel plates are used as stamps, which are microstructured with single-scaled and hierarchical textures using direct laser writing and two-beam direct laser interference patterning. The imprinted microstructures, containing pillar- and line-like textures, show increased water contact angles combined with a superoleophilic behavior. Time-resolved measurements reveal that oil droplets spread rapidly on the hierarchical textures with velocities of up to 1.4 mm2 s-1. This functionalization of PET foils creates new opportunities for a wide range of industrial applications, such as the use of oil-based instead of solvent-based paints, an improved distribution of lubricants in mechanical components or for oil-water separation in maritime surroundings.

The use of antibacterial and antifouling materials is widely being investigated to combat the increasing risk associated with bacterial infections and the evolution of drug-resistant bacteria. Efficient antibacterial materials can be fabricated by mimicking the topography found on the surface of natural antibacterial materials. Natural materials such as the wings of cicadas and dragonflies have evolved to use the structural features on their surface to attain bactericidal properties. The nanopillars/nanospikes present on these natural materials physically damage the bacterial cells that settle on the nanostructures resulting in cell lysis and death. This article reviews the role of nanostructures found on the surface of some of these natural antibacterial and antifouling materials such as lotus leaf, cicadas and dragonflies wings, shark skin, and rose petals. These natural structures provide guidelines for the design of synthetic bio-inspired materials. This review article also presents some novel fabrication techniques used to produce biomimetic micro- and nano-structures on synthetic material surfaces. The role of size, shape, aspect ratio, and spacing between the micro/nano-structures on the bactericidal properties is also discussed. Finally, the review is finished with the author's view on the future of the field. Refereed/Peer-reviewed

In this paper, NiO, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and (CeO2)0.8(Sm2O3)0.2 (SDC) nanopowders with different microstructures were obtained using hydrothermal and glycol–citrate methods. The microstructural features of the powders were examined using scanning electron microscopy (SEM). The obtained oxide powders were used to form functional inks for the sequential microextrusion printing of NiO-SDC, SDC and LSCF-SDC coatings with resulting three-layer structures of (NiO-SDC)/SDC/(LSCF-SDC) composition. The crystal structures of these layers were studied using an X-ray diffraction analysis, and the microstructures were studied using atomic force microscopy. Scanning capacitance microscopy was employed to build maps of capacitance gradient distribution over the surface of the oxide layers, and Kelvin probe force microscopy was utilized to map surface potential distribution and to estimate the work function values of the studied oxide layers. Using SEM and an energy-dispersive X-ray microanalysis, the cross-sectional area of the formed three-layer structure was analyzed—the interfacial boundary and the chemical element distribution over the surface of the cross-section were investigated. Using impedance spectroscopy, the temperature dependence of the electrical conductivity was also determined for the printed three-layer nanostructure.

Conjugated polymers (CPs) are a class of polymers that exhibit a change in size or shape in response to electrical stimuli. The unique combination of electrical and mechanical properties facilitates the fabrication of novel devices in a broad range of applications including: sensors, actuators, and lab-on-a-chip systems. The alternating single and double bonds along the polymer chain of CPs enables their electroactive properties but is also responsible for processability associated with CPs that has limited fabrication methods. Recently a photosensitive CP composite enabling additive manufacturing (AM) of 3D CP structures was developed. However, the introduction of a copolymer for mechanical stability resulted in a commensurate loss in electroactive performance, and this loss needs to be addressed to unlock to potential of 3D CP devices. This work has identified two main themes for the advancement of 3D CP devices. First, improvement of AM approaches for 3D CP devices is conducted through the development of extrusion-based direct ink writing (DIW) of passive support structures as well as the further development of existing photosensitive CP resin formulations for use in vat polymerization of 3D CP-composite structures. Secondly, the improvement of electroactive performance of 3D CP-composite devices is explored through methods to increase surface area and reduce diffusion path lengths by the deposition of hierarchical CP structures. Development of a DIW process leveraging a support gel improved resolution and quality of 3D polydimethylsiloxane (PDMS) structures enabling the fabrication of 3D CP bilayer devices. The DIW process has also been paired with the development of a PDMS-carbon nanotube composite to produce 3D tubular strain sensors for applications in fluidic networks. The electrical conductivity of CP photosensitive resin formulations has been improved through the integration of polypyrrole (PPy) functionalized carbon nanotubes. This improvement to the material properties enabled the development of a soft-template polymerization process to deposit hierarchical PPy structures on vat polymerized CP composite films. Films with hierarchical PPy features demonstrated improved electroactive performance compared to those deposited with conventional 2D PPy films. Development of these fabrication methods and improved material properties further advances the potential of 3D CP devices and bridges the gap between the micro- and nanoscales towards controllable nanoscale CP features.

Three-dimensional (3D) printing has been widely utilized to fabricate free-standing electrodes in energy-related fields. In terms of fabrication, the two most challenging limitations of 3D printed electrodes are the poor printing resolution and simple structural dimension. Here we proposed a novel process to fabricate molybdenum disulfide-polyvinylidene fluoride (MoS2-PVDF) hierarchical electrodes for energy storage applications. The 20-layer microscale PVDF films with a stable fiber width of 8.3 ± 1.2 μm were fabricated by using electrohydrodynamic (EHD) printing. MoS2 nanostructures were synthesized and assembled on the microscale PVDF fibers by using hydrothermal crystal growth. The structural and material investigations were conducted to demonstrate the geometrical morphology and materials component of the composite structure. The electrochemical measurements indicated that the MoS2-PVDF electrodes exhibited the typical charge-discharge performance with a mass specific capacitance of 60.2 ± 4.5 F/g. The proposed method offers a facile and scalable approach for the fabrication of high-resolution electrodes, which might be further developed with enhanced specific capacitance in energy storage fields.

Many aquatic creatures in nature have non-cooperative surface scaling abilities using suction organs; micro-/nano-scale structures found in different parts of the organs play an important role in this mechanism. Synthetic bioinspired suction devices have been developed, but the mechanisms of bioinspired suction system need further investigation. This paper presents the development of a synthetic adhesive disc inspired by the hillstream loach. The microscopic structures involved in adhesion of the hillstream loach were investigated. Bioinspired suction discs were designed with single-level or hierarchical micropatterned margins. Micro three-dimensional (3D) printing and micro electromechanical system (MEMs) technology were utilized in the fabrication of the discs, and the adhesion performance was tested on substrates with different roughness values. The engaging and disengaging processes of the margin were simulated by carrying out a peeling test on a submerged substrate. The interactions between the liquid film and the microstructures were observed using fluorescence microscopy. The enhanced adhesion forces due to the synergy of the hierarchically micro-patterned margin and the disc cavity were duplicated in the synthetic adhesion system.

Electrospinning is a popular method for generating long and continuous nanofibers due to its simplicity and versatility. However, conventional electrospun products have weak strength and low availability, which restrict their functionality in complex applications. Hierarchical morphology introduces additional and distinctive structural layers onto electrospun fibers. This requires either an extra fabrication step or controlling electrospinning parameters to achieve the desired morphology. Hierarchical morphology can improve the properties of electrospun nanofibers while also mitigating the undesired characteristics. This review discusses the primary and secondary hierarchical structures of electrospun nanomaterials. Hierarchical structures were found to enhance the functionality of nanomaterials and improve pore connectivity and surface areas of electrospun nanofibers. A further advantage is the ability to impart multiple functionalities on nanostructures. With a better understanding of some of the dominant hierarchical structures, nanomaterials applications in drug delivery, tissue engineering, catalysis, and energy devices industries can be improved.

A three-dimensional real-space model has been created for complex hierarchical materials by matching observed and simulated small-angle X-ray scattering patterns. The simulation is performed by arranging the positions of small primary particles and constructing an aggregate structure in a finite-sized cell., A three-dimensional real-space model has been created for hierarchical materials by matching observed and simulated small-angle X-ray scattering patterns. The simulation is performed by arranging the positions of small primary particles and constructing an aggregate structure in a finite-sized cell. In order to avoid the effect of the finite size of the cell, the cell size is extended to infinity by introducing an asymptotic form of the long-range correlations among the primary particles. As a result, simulations for small-angle X-ray scattering patterns can be performed correctly in the low-wavenumber regime (

A novel superhydrophobic/superoleophilic surface has been developed by direct surface condensation of dichloroxylene that results in a controlled coating of hyper-cross-linked polymers. Specifically, the coating was successfully applied to a melamine formaldehyde sponge and optimized by fine-tuning the reaction variables. The resulting hierarchical porous sorbents stabilized by polydimethylsiloxane exhibited an increased surface area, good physiochemical stability, high selectivity, and adsorption capacities for a variety of oils and solvents. The composite can separate oil in water emulsions with ultrahigh separation efficiency >99% over 10 cycles in liter-scale experiments, wherein the highest separation efficiency was as low as 2 ppm even with a short period of filtration, suggesting strong potential for oil/water separation and recovery.

A two-stage micromechanics technique is used to predict the elastic modulus, as well as the major and minor Poisson’s ratio of unidirectional natural fiber (NF) reinforced composites. The actual NF microstructure consists of cellulose, hemicellulose, lignin, lumen, etc., and these constituents and their contributions are neglected in classical models while quantifying their mechanical properties. The present paper addresses the effect of the real microstructure of the natural jute fiber (JF) by applying a micromechanics approach with the Finite Element Method. Six different hierarchically micro-structured JFs are considered to quantify the JF elastic properties in the first level of homogenization. Later, the JF reinforced polypropylene matrix properties are investigated in the second stage by adopting a homogenization approach. Taking into account the different hierarchical structures (HS), the fiber direction modulus (E1), transverse modulus (E2 and E3), in-plane and out-of-plane shear modulus (G12 and G23), and major (ν12, ν13) and minor (ν23, ν21) Poisson’s ratios are estimated for JF and JF reinforced polypropylene composites. The predicted elastic modulus from micromechanics models is validated against the analytical results and experimental predictions. From the present work, it is observed that the HS of NF needs to be considered while addressing the elastic properties of the NF-reinforced composite for their effective design, particularly at a higher volume fraction of NF.

Stabilizing the hydrophobic wetting state on a surface is essential in heat transfer and microfluidics. However, most hydrophobic surfaces of Si are primarily achieved through microtexturing with subsequent coating or modification of low surface energy materials. The coatings make the hydrophobic surface unstable and impractical in many industrial applications. In this work, the Si chips’ wettability transitions are yielded from the original hydrophilic state to a stable transitional hydrophobic state by texturing bamboo-leaf-like hierarchical structures (BLHSs) through a diamond grinding wheel with one-step forming. Experiments showed that the contact angles (CAs) on the BLHS surfaces increased to 97° and only reduced by 2% after droplet impacts. This is unmatched by the current texturing surface without modification. Moreover, the droplets can be split up and transferred by the BLHS surfaces with their 100% mass. When the BLHS surfaces are modified by the low surface energy materials’ coating, the hydrophobic BLHS surfaces are upgraded to be superhydrophobic (CA > 135°). More interestingly, the droplet can be completely self-sucked into a hollow micro-tube within 0.1 s without applying external forces. A new wetting model for BLHS surfaces based on the fractal theory is determined by comparing simulated values with the measured static contact angle of the droplets. The successful preparation of the bamboo-leaf-like Si confirmed that transitional wettability surfaces could be achieved by the micromachining of grinding on the hard and brittle materials. Additionally, this may expand the application potential of the key semiconductor material of Si.

Magnetic field‐directed assemblies of magnetic nanoparticles (MNPs) in ferrofluids exhibit complex interconvertible metastable patterns and structures. Formally, ferrofluid patterns are unstable – they disappear when the magnetic field is removed. The present study shows that ferrofluid patterns can be “trapped” as kinetically stable structures that encode a surprising degree of morphological detail over nanometer to millimeter length scales. An external magnetic field is used to direct assembly of oleic acid‐decorated magnetite (Fe3O4) nanoparticles to make spike and labyrinthine patterns in volatile host solvents of heptane, octane and nonane. Solvent evaporation coupled with increases in sample magnetization drive pattern formation and its permanent recording. Use of a crosslinking siloxane polymer host yields remarkably different material responses. From the trapped states in both fluid systems, previously unreported hierarchies of order emerge in nanocomposite spike structures that also exhibit orientational and magnetic anisotropy. The possibility of designing hierarchical matter from initially uncorrelated MNPs is demonstrated by a directed solid‐state transformation of the magnetic nanocomposite; the spikes template memory of their origin onto the transformation products.

The ability to create mixed morphologies using easily controlled parameters is crucial for the integration of block copolymers in advanced technologies. We have previously shown that casting an ultrathin block copolymer film on a topographically patterned substrate results in different deposited thicknesses on the plateaus and in the trenches, which leads to the co-existence of two patterns. In this work, we highlight the dependence of the dual patterns on the film profile. We suggest that the steepness of the film profile formed across the plateau edge affects the nucleation of microphase-separated domains near the plateau edges, which influences the morphology that develops on the plateau regions. An analysis of the local film thicknesses in multiple samples exhibiting various combinations of plateau and trench widths for different trench depths enabled the construction of phase diagrams, which unraveled the intricate dependence of the formed patterns not only on the curvature of the film profile but also on the fraction of the film that resides in the trenches. Our analysis facilitates the prediction of the patterns that would develop in the trenches and on the plateaus for a given block copolymer film of known thickness from the dimensions of the topographic features.

Submitted by Regina Aparecida Capeli (regina.capeli@unesp.br) on 2022-06-07T22:04:06Z No. of bitstreams: 1 TESE DEFESA DOUTORADO Regina Ap Capeli da Silva.pdf: 7852682 bytes, checksum: a61f6e1e46ce3795c8281e7a64ab3f9c (MD5) Rejected by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br), reason: Favor refazer a submissão seguindo as orientações abaixo: 1 - Inserir a cópia da ata de defesa no lugar do atestado de aprovação. Agradecemos a compreensão on 2022-06-08T13:11:47Z (GMT) Submitted by Regina Aparecida Capeli (regina.capeli@unesp.br) on 2022-06-09T21:59:04Z No. of bitstreams: 1 TESE DEFESA DOUTORADO Regina Ap Capeli da Silva.pdf: 7967630 bytes, checksum: e817cff8b9739517c5ceff180e2e22bf (MD5) Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2022-06-10T12:35:19Z (GMT) No. of bitstreams: 1 silva_rac_dr_bauru.pdf: 7967630 bytes, checksum: e817cff8b9739517c5ceff180e2e22bf (MD5) Made available in DSpace on 2022-06-10T12:35:19Z (GMT). No. of bitstreams: 1 silva_rac_dr_bauru.pdf: 7967630 bytes, checksum: e817cff8b9739517c5ceff180e2e22bf (MD5) Previous issue date: 2022-04-29 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) As estruturas de WO3/Ag foram sintetizadas com sucesso pela rota hidrotérmica, utilizando como precursores o ácido tunguístico, o peróxido de hidrogênio e nitrato de prata. A síntese de nanocompósitos de WO3/Ag foi feita nas concentrações de Ag (prata) igual a 0,01 M, 0,05 M e 0,20 M. A composição de 0,20M de Ag foi submetida à diferentes temperaturas de tratamento hidrotermal. Os materiais nanoestruturados sintetizados foram caracterizados por Difração de Raios-X (DRX), Espectroscopia Raman, Espectroscopia no Infravermelho com Transformada de Fourier (FTIR), Microscopia Eletrônica de Varredura (MEV/FEG), Microscopia Eletrônica de Transmissão (MET), Espectroscopia Ultravioleta-Visível (UV-Vis), Isotermas de adsorção (BET), Fotoluminescência (PL), Espectroscopia de Fotoelétrons Excitados por Raios-X (XPS) e Análise Termogravimétrica (TG-DSC). As amostras foram submetidas a testes fotocatalíticos e biológicos. Para os testes biológicos foram realizados os testes de Concentração Inibitória Mínima (CIM), sob diferentes concentrações. Para os testes de atividade fotocatalítica, a decomposição de um corante sintético, Rodamina B, sob irradiação de lâmpada LED 467 nm, foram estudados. Com a análise dos resultados obtidos foi possível se estabelecer correlações entre a atividade fotocatalítica e bactericida com as propriedades estruturais, morfológicas e de superfície. Como resultado, verificou-se que a quantidade de Ag e a temperatura de síntese são fatores cruciais na formação de várias arquiteturas hierárquicas 3D novas e complexas de WO3. Os resultados mostraram a melhora da cristalinidade e a redução da densidade de estados eletrônicos localizados com o aumento da temperatura de síntese. A amostra sintetizada com a maior concentração do sal de Ag e de maior temperatura de síntese apresentou melhores resultados fotocatalíticos. Os biotestes revelaram que as propriedades antibacterianas das estruturas hierárquicas 3D de WO3 decoradas com NPs de Ag foram efetivamente afetadas pela forma e tamanho. WO3/Ag structures were successfully synthesized by the hydrothermal route, using tungstic acid, hydrogen peroxide and silver nitrate as precursors. The synthesis of WO3/Ag nanocomposites was carried out at Ag (silver) concentrations equal to 0.01 M, 0.05 M and 0.20 M. The 0.20M Ag composition was subjected to different hydrothermal treatment temperatures. The synthesized nanostructured materials were characterized by X-Ray Diffraction (XRD), Raman spectroscopy Scanning Electron Microscopy (SEM/FEG), Fourier Transform Infrared Spectroscopy (FTIR), SEM-FEG, Transmission electron microscopy (TEM), Ultraviolet-Visible Spectroscopy (UV-Vis), Adsorption isotherms (BET) method, Photoluminescence (PL), X-Ray Excited Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TG-DSC). The samples were submitted to photocatalytic and biological tests. For the biological tests, the Minimum Inhibitory Concentration (MIC) tests were applied, under different concentrations. For the photocatalytic activity tests, the decomposition of a synthetic dye, Rhodamine B, under 467 nm LED lamp irradiation, was studied. With the analysis of the obtained results, it was possible to establish correlations between the photocatalytic and bactericidal activity with the structural, morphological and surface properties. As a result, it was found that the amount of Ag and the synthesis temperature are crucial factors in the formation of several new and complex hierarchical 3D architectures of WO3. The results showed an improvement in crystallinity and a reduction in the density of localized electronic states with increasing synthesis temperature. The sample synthesized with the highest concentration of Ag salt and the highest synthesis temperature showed better photocatalytic results. Biotests revealed that the antibacterial properties of the 3D hierarchical structures of WO3 decorated with Ag NPs were effectively affected by shape and size.

Fabrication of scaffolds with hierarchical structures exhibiting the blood vessel topological and biochemical features of the native extracellular matrix that maintain long-term patency remains a major challenge. Within this context, scaffold assembly using biodegradable synthetic polymers (BSPs) via electrospinning had led to soft-tissue-resembling microstructures that allow cell infiltration. However, BSPs fail to exhibit the sufficient surface reactivity, limiting protein adsorption and/or cell adhesion and jeopardizing the overall graft performance. Here, we present a methodology for the fabrication of three-layered polycaprolactone (PCL)-based tubular structures with biochemical cues to improve protein adsorption and cell adhesion. For this purpose, PCL was backbone-oxidized (O-PCL) and cast over a photolithography-manufactured microgrooved mold to obtain a bioactive surface as demonstrated using a protein adsorption assay (BSA), Fourier transform infrared spectroscopy (FTIR) and calorimetric analyses. Then, two layers of PCL:gelatin (75:25 and 95:5 w/w), obtained using a novel single-desolvation method, were electrospun over the casted O-PCL to mimic a vascular wall with a physicochemical gradient to guide cell adhesion. Furthermore, tensile properties were shown to withstand the physiological mechanical stresses and strains. In vitro characterization, using L929 mouse fibroblasts, demonstrated that the multilayered scaffold is a suitable platform for cell infiltration and proliferation from the innermost to the outermost layer as is needed for vascular wall regeneration. Our work holds promise as a strategy for the low-cost manufacture of next-generation polymer-based hierarchical scaffolds with high bioactivity and resemblance of ECM’s microstructure to accurately guide cell attachment and proliferation.

In this study, the modification of leather surface by application of TiO2-SiO2-GLYMO (3-Glycidyloxypropyltrimethoxysilane) nanocomposite coating and plasma treatment with N2 gas activation is investigated by using Small and Wide Angle X-ray scattering methods. The protective properties were tried to be developed with TEOS and HMDSO polymers’ usage in the coating process by following and controlling nano scale structural changes. The main aim was the controls of nanoscaled surface modifications and determination of the best coating process by keeping natural structure of the leathers. These scattering methods were useful to investigate the coating effects on the PTLs (Plasma Treated Leathers)’ internal structures including collagen microfibers and nanofibers which are hierarchical structures of triple helix collagen. The main purpose of the work was investigate whether the structural change in the natural form of the leather is present or not in the molecular-nanoscopic and microscopic scales after the coating and the applied physico-bio-chemical processes. On the other hand, the successful protective coatings and surface modifications were determined with SAXS analyses by controlling the shape, size and distance distributions of the appeared nanoglobular aggregations. The observations of structural changes taking place within collagen fibrils as a result of surface modification provides new insight into the nature of finishing and informs future processing developments. © 2020, © 2020 Taylor & Francis.

Il cambiamento climatico e uno dei temi più urgenti nel dibattito pubblico, incluso nell’Agenda 2030 per lo sviluppo sostenibile adottata dalle Nazioni Unite, a causa dei rischi che può comportare per la vita umana. Esso rappresenta un fenomeno multidimensionale definito da diverse dimensioni, ognuna delle quali misurata da un insieme di variabili direttamente osservabili, che riguardano le emissioni di gas serra, le cause del cambiamento climatico, le sue conseguenze per gli umani e la natura e gli sforzi messi in campo dal genere umano per evitare e adattarsi a tali conseguenze. In questo lavoro, introduciamo un nuovo approccio basato su modello per studiare questo fenomeno e le sue diverse caratterizzazioni nei paesi europei. La proposta metodologica ha l’obiettivo di costruire un sistema di indicatori compositi per identificare i principali fattori che determinano il cambiamento climatico e fornire di conseguenza indicazioni per attuare politiche nel contesto europeo volte a combattere il cambiamento climatico. Nowadays climate change is one of the most urgent topics in public de bate, also included into the 2030 Agenda for Sustainable Development adopted by the United Nations, because of its risks for human life. It represents a multidimensional phenomenon defined by different dimensions that pertain to greenhouse as emissions, human causes of climate change, impacts on humans and natural systems, and efforts of human to avoid and adapt to the consequences, each of which is described by a set of variables directly observed. In this paper, we introduce a new model-based approach to study this phenomenon and its different characterization in European countries. The proposal aims at building a system of composite indicators in order to understand the main determinants of this phenomenon, and to provide guidelines for policy decisions to combat climate change in the European Union framework.

Pressure sensitivity and wide range are two crucial features of flexible electromechanical sensors for applications in the next‐generation of intelligent electronics, such as wearable healthcare monitors and soft human–machine interfaces. Conventional pressure sensors have a narrow pressure range (

Two frontier crystalline porous framework materials, namely, metal‐organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely explored owing to their outstanding physicochemical properties. While each type of framework has its own intrinsic advantages and shortcomings for specific applications, combining the complementary properties of the two materials allows the engineering of new classes of hybrid porous crystalline materials with properties superior to the individual components. Since the first report of MOF/COF hybrid in 2016, it has rapidly evolved as a novel platform for diverse applications. The state‐of‐art advances in the various synthetic approaches of MOF/COF hybrids are hereby summarized, together with their applications in different areas. Perspectives on the main challenges and future opportunities are also offered in order to inspire a multidisciplinary effort toward the further development of chemically diverse, multi‐functional hybrid porous crystalline materials., This review provides a systematic summary of the synthetic protocols of hybrid materials based on metal‐ organic frameworks (MOFs) and covalent organic frameworks (COFs), as well as an overview of their application in various fields. Together with perspectives on the main challenges and opportunities, the timely review should inspire future research efforts toward the rational development of functional MOF/COF hybrids.

Plant and animal surfaces have become a model for preparing special synthetic surfaces with low wettability, reflectivity, or antibacterial properties. Processes that lead to the creation of replicas of natural character use two-step imprinting methods. This article describes a technique of synthetic polymer surface preparation by the process of two-stage imprinting. The laboratory-prepared structure copies the original natural pattern at the micrometer and sub-micrometer levels, supplemented by a new substructure. The new substructure identified by the scanning electron microscope is created at the nanometer level during the technological process. The nanostructure is formed only under the conditions that a hierarchical structure forms the surface of the natural replicated pattern, the replication mold is from a soft elastomeric material, and the material for producing the synthetic surface is a polymer capable of crystallizing. A new nanometer substructure formation occurs when the polymer cools to standard laboratory temperature and atmospheric pressure.

The process of the hydrothermal synthesis of hierarchically organized nanomaterials with the core-shell structure with the composition ((CeO2)0.8(Sm2O3)0.2)@NiO was studied, and the prospects for their application in the formation of planar composite structures using microextrusion printing were shown. The hydrothermal synthesis conditions of the (CeO2)0.8(Sm2O3)0.2 nanospheres were determined, and the approach to their surface modification by growing the NiO shell with the formation of core-shell structures equally distributed between the larger nickel(II) oxide nanosheets was developed. The resulting nanopowder was used as a functional ink component in the microextrusion printing of the corresponding composite coating. The microstructure of the powders and the oxide coating was studied by scanning (SEM) and transmission electron microscopy (TEM), the crystal structure was explored by X-ray diffraction analysis (XRD), the set of functional groups in the powders was studied by Fourier-transform infrared spectroscopy (FTIR) spectroscopy, and their thermal behavior in an air flow by synchronous thermal analysis (TGA/DSC). The electronic state of the chemical elements in the resulting coating was studied using X-ray photoelectron spectroscopy (XPS). The surface topography and local electrophysical properties of the composite coating were studied using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). Using impedance spectroscopy, the temperature dependence of the specific electrical conductivity of the obtained composite coating was estimated.

Hierarchical lattices are structures composed of self-similar or dissimilar architected metamaterials that span multiple length scales. Hierarchical lattices have superior and tunable properties when compared to conventional lattices, and thus, open the door for a wide range of material property manipulation and optimization. Using finite element analysis, we investigate the energy absorption capabilities of 3D hierarchical lattices for various unit cells under low strain rates and loads. In this study, we use fused deposition modeling (FDM) 3D printing to fabricate a dog bone specimen and extract the mechanical properties of thermoplastic polyurethane (TPU) 85A with a hundred percent infill printed along the direction of tensile loading. With the numerical results, we observed that the energy absorption performance of the octet lattice can be enhanced four to five times by introducing a hierarchy in the structure. Conventional energy absorption structures such as foams and lattices have demonstrated their effectiveness and strengths, this research aims at expanding the design domain of energy absorption structures by exploiting 3D hierarchical lattices. The result of introducing a hierarchy to a lattice on the energy absorption performance is investigated by varying the hierarchical order from a first-order octet to a second-order octet. In addition, the effect of relative density on the energy absorption is isolated by creating a comparison between a first-order octet lattice with an equivalent relative density as a second-order octet lattice. The compression behaviors for the second order octet, dodecahedron, and truncated octahedron are studied. The effect of changing the cross-sectional geometry of the lattice members with respect to the energy absorption performance is investigated. Changing the orientation of the second-order cells from 0 to 45 degrees has a considerable impact on the force–displacement curve, providing a 20% increase in energy absorption for the second-order octet. Analytical solutions of the effective elasticity modulus for the first- and second-order octet lattices are compared to validate the simulations. The findings of this paper and the provided understanding will aid future works in lattice design optimization for energy absorption.

Detailed and accurate three-dimensional (3D) information about the morphology of hierarchically structured materials is derived from multi-scale X-ray computed tomography (XCT) and subsequent 3D data reconstruction. High-resolution X-ray microscopy and nano-XCT are suitable techniques to nondestructively study nanomaterials, including porous or skeleton materials. However, laboratory nano-XCT studies are very time-consuming. To reduce the time-to-data by more than an order of magnitude, we propose taking advantage of a monitored tomographic reconstruction. The benefit of this new protocol for 3D imaging is that the data acquisition for each projection is interspersed by image reconstruction. We demonstrate this new approach for nano-XCT data of a novel transition-metal-based materials system: MoNi4 electrocatalysts anchored on MoO2 cuboids aligned on Ni foam (MoNi4/MoO2@Ni). Quantitative data that describe the 3D morphology of this hierarchically structured system with an advanced electrocatalytically active nanomaterial are needed to tailor performance and durability of the electrocatalyst system. We present the framework for monitored tomographic reconstruction, construct three stopping rules for various reconstruction quality metrics and provide their experimental evaluation.

Significance While microwave absorption is a widely pursued topic, a conceptual-based design can offer a theoretical basis for generalization and improvements. We offer a design recipe for ultrabroadband absorption based on the use of electrical dipole resonance in a metallic ring to generate, via interaction with its image resonance, two high-impedance resonances. Impedance matching over the frequency range in between the two resonances is obtained by adding resistance to the metallic ring. To extend the absorption to an ultrabroadband spectrum, we employ a double-layer self-similar structure in conjunction with absorption of the diffracted waves at the higher frequency end. The resulting absorber pushes the overall performance close to the causality limit over a large absorption bandwidth., By introducing metallic ring structural dipole resonances in the microwave regime, we have designed and realized a metamaterial absorber with hierarchical structures that can display an averaged −19.4 dB reflection loss (∼99% absorption) from 3 to 40 GHz. The measured performance is independent of the polarizations of the incident wave at normal incidence, while absorption at oblique incidence remains considerably effective up to 45°. We provide a conceptual basis for our absorber design based on the capacitive-coupled electrical dipole resonances in the lateral plane, coupled to the standing wave along the incident wave direction. To realize broadband impedance matching, resistive dissipation of the metallic ring is optimally tuned by using the approach of dispersion engineering. To further extend the absorption spectrum to an ultrabroadband range, we employ a double-layer self-similar structure in conjunction with the absorption of the diffracted waves at the higher end of the frequency spectrum. The overall thickness of the final sample is 14.2 mm, only 5% over the theoretical minimum thickness dictated by the causality limit.

Pristine graphene is one of the strongest materials known in the world, and may play important roles in structural and functional materials. In order to utilize the extraordinary mechanical properties in practical engineering structures, graphene should be assembled into macroscopic structures such as graphene-based papers, fibers, foams, etc. However, the mechanical properties of graphene-based materials such as Young’s modulus and strength are 1–2 orders lower than those of pristine monolayer graphene. Many efforts have been made to unveil the multi-scale structure–property relations of graphene-based materials with hierarchical structures spanning the nanoscale to macroscale, and significant achievements have been obtained to improve the mechanical performance of graphene-based materials through composition and structure optimization across multi-scale. This review aims at summarizing the currently theoretical, simulation, and experimental efforts devoted to the multi-scale structure–property relation of graphene-based layer materials including defective monolayer graphene, nacre-like and laminar nanostructures of multilayer graphene, graphene-based papers, fibers, aerogels, and graphene/polymer composites. The mechanisms of mechanical property degradation across the multi-scale are discussed, based on which some multi-scale optimization strategies are presented to further improve the mechanical properties of graphene-based layer materials. We expect that this review can provide useful insights into the continuous improvement of mechanical properties of graphene-based layer materials.

Significance Despite emerging breakthroughs in the achievement of numerous elegant biomimetic structures that impart fascinating functionalities, bioinspired materials still suffer from poor structural durability, chemical reliability, flexibility, and optical transparency, as well as unaffordable cost and low throughput, thus preventing their broad real-life applications. In striking contrast to conventional wisdom, we demonstrate that the usually avoided and detrimental elastic crack phenomenon can be translated into powerful configurable-crack engineering to achieve structures and functions that are impossible to realize even using state-of-the-art techniques. Our approach dramatically enriches the freedom and flexibility in the design of materials to mimic various natural living organisms and paves the road for translating nature’s inspirations into real-world applications., Three-dimensional hierarchical morphologies widely exist in natural and biomimetic materials, which impart preferential functions including liquid and mass transport, energy conversion, and signal transmission for various applications. While notable progress has been made in the design and manufacturing of various hierarchical materials, the state-of-the-art approaches suffer from limited materials selection, high costs, as well as low processing throughput. Herein, by harnessing the configurable elastic crack engineering—controlled formation and configuration of cracks in elastic materials—an effect normally avoided in various industrial processes, we report the development of a facile and powerful technique that enables the faithful transfer of arbitrary hierarchical structures with broad material compatibility and structural and functional integrity. Our work paves the way for the cost-effective, large-scale production of a variety of flexible, inexpensive, and transparent 3D hierarchical and biomimetic materials.

The deposition of ice on wings and tails surfaces of aircrafts often alters the airflow reducing the lift force and causing aerodynamic stall. In order to prevent these kind of serious problems, de-icing and anti-icing systems, which act by removing the ice once it has formed, and by preventing its formation, respectively, are usually employed. In particular, the anti-icing superhydrophobic and icephobic coatings can be achieved by designing and realizing nanostructured surfaces by taking inspiration from effective surface present in nature, e.g., the lotus leaf. However, this process is often expensive and requires specialized equipment. The effort of the present work is to find out a simplified and not-expensive method to prepare superhydrophobic coatings to be applied on large aircraft surfaces. Among the investigated methods, the deposition of several layers of a homogeneous hydrophobic silica nanoparticles by using a simple aerograph allowed to build-up a coating which exhibits a contact angle of 154°. The coating withstands to aging tests simulating flight conditions. Also during typical flight conditions, i.e., −12 °C and 0.5 bar, it retains its hierarchical superficial morphology with roughness features from nano- to micro-scale and shows contact angle higher than the commercial reference.

Hierarchical silicon structures consisting of micropyramids and nanowire arrays are fabricated by two-step chemical etching processes aimed at achieving cost and time effectiveness constraints without using any expensive vacuum system or complicated lithography process. The hierarchical structures can suppress the average reflectance to as low as 4.3% from 300 to 1100 nm without causing poor minority carrier lifetimes, exhibiting excellent broadband light-harvesting abilities with minimal recombination losses, which is the key point to design high-performance nanostructured solar cells. By utilizing hierarchical structures in the practical solar cells application, the short-circuit current density (JSC) shows a significant enhancement from 21.5 to 28.7 mA/cm2, and the conversion efficiency is enhanced by a factor of 35%. Such a significant enhancement is attributed not only to the superior light harvesting achieved by hierarchical structures but also to the benefit of small electrical losses in the solar cells. Thus, the concept and technique presented in this paper open avenues for developing high-performance structure solar devices.

Peptide derivatives and, most specifically, their self-assembled supramolecular structures are being considered in the design of novel biofunctional materials. Although the self-assembly of triphenylalanine homopeptides has been found to be more versatile than that of homopeptides containing an even number of residues (i.e. diphenylalanine and tetraphenylalanine), only uncapped triphenylalanine (FFF) and a highly aromatic analog blocked at both the N- and C-termini with fluorenyl-containing groups (Fmoc-FFF-OFm), have been deeply studied before. In this work, we have examined the self-assembly of a triphenylalanine derivative bearing 9-fluorenylmethyloxycarbonyl and benzyl ester end-capping groups at the N- and C-termini, respectively (Fmoc-FFF-OBzl). The antiparallel arrangement clearly dominates in β-sheets formed by Fmoc-FFF-OBzl, whereas the parallel and antiparallel dispositions are almost isoenergetic in Fmoc-FFF-OFm β-sheets and the parallel one is slightly favored for FFF. The effects of both the peptide concentration and the medium on the self-assembly process have been examined considering Fmoc-FFF-OBzl solutions in a wide variety of solvent:co-solvent mixtures. In addition, Fmoc-FFF-OBzl supramolecular structures have been compared to those obtained for FFF and Fmoc-FFF-OFm under identical experimental conditions. The strength of π-π stacking interactions involving the end-capping groups plays a crucial role in the nucleation and growth of supramolecular structures, which determines the resulting morphology. Finally, the influence of a non-invasive external stimulus, ultrasounds, on the nucleation and growth of supramolecular structures has been examined. Overall, FFF-based peptides provide a wide range of supramolecular structures that can be of interest in the biotechnological field., The authors gratefully acknowledge financial support provided by Ministerio de Asuntos Económicos y Transformación Digital, con Fondos de la Unión Europea - FEDER (MINECO/FEDER; RTI2018-098951-B-I00), Agència de Gestió d'Ajuts Universitaris i de Recerca (2017SGR359), and Gobierno de Aragón (research group Aminoácidos y Péptidos; E19_20R). M.M.P.-M. is thankful for the Junior Beatriz Galindo Fellowship (BG20/00216).

Hierarchical Zn-ZSM-5 photocatalyst structures were synthesized via a hydrothermal one-pot synthesis route using a double template. Activated attapulgite (Si-ATP) and zinc nitrate (Zn(NO3)2) precursors were used as silicon and zinc sources, respectively. The structural properties, morphology, photocatalytic activity and the texture properties of the synthesized Zn-ZSM-5 photocatalysts were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), diffracted ultraviolet–visible (UV–Vis) spectrometry (DRUV–Vis) and N2 adsorption/desorption, respectively. It was found that the composites exhibit a typical MFI framework structure, a hexahedral twin structure and typical UV absorption peaks at 292 nm and 246 nm, when the Zn/Si mole ratio reaches its optimum value of 1:100. The hierarchical nanocrystals exhibit a similar Brunauer–Emmett–Teller surface area (309 m2 g−1) and a high mesopore ratio (37.47%) as compared to commercial zeolites. Sub-nano-sized zinc oxide (ZnO) particles with small size moieties were implanted and isolated in the silica matrices of micro-mesoporous zeolite, which had a significant photocatalytic activity and reusability of degrading methylene blue (MB) dyeing wastewater. Using a 500 W mercury lamp with the wavelength range from 185–500 nm operating during an illumination time of 30 min, the concentration of MB decreases significantly in the presence of Zn-ZSM-5 photocatalyst leading to a 95.56% of degradation, where the ratio still remained at 94.32% after six times of reuse.

We report the design and fabrication by laser direct writing via two photons polymerization of innovative hierarchical structures with cell-repellency capability. The structures were designed in the shape of “mushrooms”, consisting of an underside (mushroom’s leg) acting as a support structure and a top side (mushroom’s hat) decorated with micro- and nanostructures. A ripple-like pattern was created on top of the mushrooms, over length scales ranging from several µm (microstructured mushroom-like pillars, MMP) to tens of nm (nanostructured mushroom-like pillars, NMP). The MMP and NMP structures were hydrophobic, with contact angles of (127 ± 2)◦ and (128 ± 4)◦ , respectively, whereas flat polymer surfaces were hydrophilic, with a contact angle of (43 ± 1)◦ . The cell attachment on NMP structures was reduced by 55% as compared to the controls, whereas for the MMP, a reduction of only 21% was observed. Moreover, the MMP structures preserved the native spindle-like with phyllopodia cellular shape, whereas the cells from NMP structures showed a round shape and absence of phyllopodia. Overall, the NMP structures were more effective in impeding the cellular attachment and affected the cell shape to a greater extent than the MMP structures. The influence of the wettability on cell adhesion and shape was less important, the cellular behavior being mainly governed by structures’ topography.

Nowadays, the demand for surface functionalized plastics is constantly rising. To address this demand with an industry compatible solution, here a strategy is developed for producing hierarchical microstructures on polyethylene terephthalate (PET) by hot embossing using a stainless steel stamp. The master was structured using three laser-based processing steps. First, a nanosecond-Direct Laser Writing (DLW) system was used to pattern dimples with a depth of up to 8 µm. Next, the surface was smoothed by a remelting process with a high-speed laser scanning at low laser fluence. In the third step, Direct Laser Interference Patterning (DLIP) was utilized using four interfering sub-beams to texture a hole-like substructure with a spatial period of 3.1 µm and a depth up to 2 µm. The produced stamp was used to imprint PET foils under controlled temperature and pressure. Optical confocal microscopy and scanning electron microscopy imaging showed that the hierarchical textures could be accurately transferred to the polymer. Finally, the wettability of the single- and multi-scaled textured PET surfaces was characterized with a drop shape analyzer, revealing that the highest water contact angles were reached for the hierarchical patterns. Particularly, this angle was increased from 77° on the untreated PET up to 105° for a hierarchical structure processed with a DLW spot distance of 60 µm and with 10 pulses for the DLIP treatment.

International audience; The use of plant proteins to design colloidal food systems is a hot topic in the current context of the protein transition. However, replacing animal-derived proteins (in particular, dairy proteins) that have been traditionally used for this purpose by plant proteins is a challenge from various perspectives, and in particular, because of drastically different solubility and functionality. A possible route to mitigate these issues is to combine plant and dairy proteins, providing that their interactions can be understood from the molecular to the macroscopic scale. This review addresses the major advances that have occurred in the field of such blend-based systems, all the way from their behaviour in aqueous dispersions to their potential applications in gels, foams and emulsions.

Pt based materials are the most efficient electrocatalysts for the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in fuel cells. Maximizing the utilization of Pt based materials by modulating their morphologies to expose more active sites is a fundamental objective for the practical application of fuel cells. Herein, we report a new class of hierarchically skeletal Pt-Ni nanocrystals (HSNs) with a multi-layered structure, prepared by an inorganic acid-induced solvothermal method. The addition of H2SO4 to the synthetic protocol provides a critical trigger for the successful growth of Pt-Ni nanocrystals with the desired structure. The Pt-Ni HSNs synthesized by this method exhibit enhanced mass activity of 1.25 A mgpt−1 at 0.9 V (versus the reversible hydrogen electrode) towards ORR in 0.1-M HClO4, which is superior to that of Pt-Ni multi-branched nanocrystals obtained by the same method in the absence of inorganic acid; it is additionally 8.9-fold higher than that of the commercial Pt/C catalyst. Meanwhile, it displays enhanced stability, with only 21.6% mass activity loss after 10,000 cycles (0.6–1.0 V) for ORR. Furthermore, the Pt-Ni HSNs show enhanced activity and anti-toxic ability in CO for MOR. The superb activity of the Pt-Ni HSNs for ORR and MOR is fully attributed to an extensively exposed electrochemical surface area and high intrinsic activity, induced by strain effects, provided by the unique hierarchically skeletal alloy structure. The novel open and hierarchical structure of Pt-Ni alloy provides a promising approach for significant improvements of the activity of Pt based alloy electrocatalysts. © 2021 Dalian Institute of Chemical Physics, the Chinese Academy of Sciences. This work was supported by the National Key Research and Development Plan (2017YFB0103001), the link project of the National Natural Science Foundation of China and Fujian Province (U1705252), the Guangxi Science and Technology Projects (AA17204083, AB16380030), the innovation project of Guangxi Graduate Education (YCBZ2019012).

Network operators cannot change their foot-print to upgrade the entire network to support SDN from scratch. Hence, network operators adapted the original SDN concept into a hybrid SDN approach to have a pragmatic, evolutionary, and economically viable solution. This article tests an SDN architecture based on a hierarchical structure of a Software-Defined Transport Networking (SDTN) controller, which deals with the end-to-end service provision and topology collection on top of a set of SDN controllers for each technological domain. The authors demonstrate L3/L2 VPN service deployment using an underlay multi-domain IP/Optical network in a field trial. The approach allows a service provider to migrate brownfield scenarios into SDN domains using programmatic interfaces. © 2021 IEEE.

Direct laser scribing, an advanced printing technique, has been recently developed to enable the carbonization of carbonaceous precursors in a rapid, precise, and cost-effective manner. Herein, it is reported that metal−organic frameworks (MOFs) can be converted into patterned derived carbon with desired structural features using a CO2 infrared laser system. Metal species in MOFs play a key role in the morphology, porous structure, and crystallinity of the resulting laser-induced products by studying six representative MOFs. Diverse features such as ordered porous structure and continuous network microstructure can be obtained in the laser-induced MOF-derived carbon, which is influenced by the melting and boiling points of metals and their magnetic and catalytic behaviors. Furthermore, a core–shell structured composite (MOF-199@ZIF-67) has been designed and prepared for the fabrication of 12-interdigital electrodes derived from the composite by laser-assisted printing. The as-obtained electrodes with highly porous and hierarchical structure show an enhanced specific capacitance for micro-supercapacitors (MSCs). This work provides a complementary heat treatment method to produce MOF-derived carbon nanomaterials with desired structural features and patterns for MSCs and micro-device-related applications. Nanyang Technological University This work was supported by the National Natural Science Foundation of China (22075248). The authors acknowledge the financial support from the Nanyang Environment and Water Research Institute (Core Fund), Nanyang Technological University, Singapore.

Bone was a crucial biological material for the evolution of large terrestrial organisms and is today essential for most of our daily activities and well-being. From an engineering perspective, this living material features highly desirable properties for modern load-bearing structures. It is made of abundant and environmental-friendly building blocks, which are combined into a tough and durable structure that can continuously modify itself to adapt to changes in the mechanical load imposed by the surroundings. In this review article, we compile and discuss scientific findings that allow us to understand bone as a complex system with properties that emerge from cell-mediated interactions of molecules and particles at multiple length scales. Analogous to other complex systems, such interactions lead to self-organization, hierarchical structures and adaptive behavior without the need of a central controlling unit. A rich range of physical, chemical and biological phenomena provide a framework for information to be generated and processed in this complex system. Understanding the interplay between such underlying phenomena and their emerging properties should help the diagnosis and treatment of bone-related medical conditions and might provide guidelines for the future development of more sustainable materials and engineering structures.

Multidimensional phenomena are often characterised by nested latent concepts ordered in a hierarchical structure, from the most specific to the most general ones. In this paper, we model a nonnegative data covariance matrix by extending the Ultrametric Correlation Model to covariance matrices. The proposal is a parsimonious model which identifies a partition of variables in a reduced number of groups, and the relationships among them via the ultrametric property. The proposed model is applied to investigate the relationships among the dimensions of the Teachers’ Job Satisfaction in Italian secondary schools.

The presence of the polycationic macromolecule poly(diallyldimethylammonium chloride) (poly-DADMAC) has a strong effect on the shape and size of colloidal gold nanoparticles formed by the reduction of tetrachloroauric acid with ascorbic acid in aqueous solution. It slows down nanoparticle growth and supports the formation of nonspherical, partially highly fractal and hierarchical nanoparticle shapes. Four structural levels have been recognized from the near-spherical gold nanoparticles in the lower nanometer range over compact aggregates in the midnanometer range and flower and star-like particles in the submicron range up to larger filamentous aggregates. High-contrast scanning electron microscope (SEM) images show that single gold nanoparticles and clusters of them are connected by bundles of macromolecules in large aggregates. The investigation showed that a large spectrum of different nanoparticle shapes and sizes can be accessed by tuning the poly-DADMAC concentrations and their ratio to other reactants. The nanoassemblies with a very high specific surface area might be of interest for SERS and heterogeneous catalysis.

Liquid metal dealloying (LMD) has recently attracted significant attention. Because the LMD process enables the production of three-dimensional (3D) interconnected non-noble metallic materials. In addition, the metallic melt medium is useful for the development of heterostructure (HS) metal–metal composites. However, the solidified liquid metal phase (low melting point metals such as Mg, Bi, Sn, or Cu) has a much lower strength than the developed ligament phase (e.g., Fe, FeCr, Ti, etc.). In this study, the soft Mg phase was strengthened by adding alloying element of Ni. A eutectic composition of Mg–10 at.% Ni melt leads to the formation of fine eutectic structure of (Mg–Mg2Ni) within 3D interconnected morphology. This hierarchical heterostructured composite consisted of FeCr ligament and Mg–Mg2Ni lamellar, and a high yield strength of 280 MPa and a noticeable elongation (1.5%) were achieved. The complex 3D morphology of ligament and lamellar geometrically constraint each other, and it prevents the early fracture of brittle Mg–Mg2Ni lamellar phase. The alloy design for the LMD melt gives insights for hierarchical HS materials with outstanding mechanical properties for structural applications. © 2021 The Authors. This work was supported by JSPS KAKENHI (Grant Number JP20J14001 ). Yeonbeom Jeong acknowledges the support from the GP-MS at Tohoku University . This work has supported by the National Research Foundation of Korea grant funded by the Korea government(MSIT) (No. NRF-2021R1C1C1007645 ). This work was primarily supported by a Grant-in-Aid for Scientific Research on Innovative Areas “Science of New-Class of Materials Based on Elemental Multiplicity and Heterogeneity (Grant No. 18H05452)” from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT, Japan) (H.K and T.W). This work was performed under the ICC-IMR Program of the Institute for Materials Research, Tohoku University.

We report the design and fabrication by laser direct writing via two photons polymerization of innovative hierarchical structures with cell-repellency capability. The structures were designed in the shape of “mushrooms”, consisting of an underside (mushroom’s leg) acting as a support structure and a top side (mushroom’s hat) decorated with micro- and nanostructures. A ripple-like pattern was created on top of the mushrooms, over length scales ranging from several µm (microstructured mushroom-like pillars, MMP) to tens of nm (nanostructured mushroom-like pillars, NMP). The MMP and NMP structures were hydrophobic, with contact angles of (127 ± 2)° and (128 ± 4)°, respectively, whereas flat polymer surfaces were hydrophilic, with a contact angle of (43 ± 1)°. The cell attachment on NMP structures was reduced by 55% as compared to the controls, whereas for the MMP, a reduction of only 21% was observed. Moreover, the MMP structures preserved the native spindle-like with phyllopodia cellular shape, whereas the cells from NMP structures showed a round shape and absence of phyllopodia. Overall, the NMP structures were more effective in impeding the cellular attachment and affected the cell shape to a greater extent than the MMP structures. The influence of the wettability on cell adhesion and shape was less important, the cellular behavior being mainly governed by structures’ topography.