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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.

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.

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

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.

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.

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.

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).

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.

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.

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.

Over millions of years of evolution, the species in nature have gradually possessed some bio-structures. These structures have specific mechanical, hydrodynamic, optical, and electrical properties, which provide human the valuable enlightenments to design and fabricate high-performance components and devices. However, the traditional fabrication technologies cannot accurately reproduce or imitate the complicated and exquisite bioinspired structures, which restricts the development and application of biomimetic study. Due to the emergence and development of 3D printing technologies, more bioinspired structures can be designed and fabricated. Recent progress in 3D printing of structures inspired by the species in nature, such as springtails, filefish, abalone shell, conch shell, wheat awn, plant stem and wood, etc., are reviewed in this paper and the current challenge and future development for 3D printing of bioinspired structures are discussed.

Atomically precise ligand-protected nanoclusters (NCs) constitute an important class of compounds that exhibit well-defined structures and, when sufficiently small, evident molecular properties. NCs provide versatile building blocks to fabricate hierarchical superstructures. The assembly of NCs indeed offers opportunities to devise new materials with given structures and able to carry out specific functions. In this Concept article, we highlight the possibilities offered by NCs in which the physicochemical properties are controlled by the introduction of foreign metal atoms and/or modification of the composition of the capping monolayer with functional ligands. Different approaches to assemble NCs into dimers and higher hierarchy structures and the corresponding changes in physicochemical properties are also described.

Skeletal muscles are considered to date the best existing actuator in nature thanks to their hierarchical multiscale fibrous structure capable to enhance their strength and contractile performances. In recent years, driven by the growing of the soft robotics and tissue-engineering research field, many biomimetic soft actuators and scaffolds were designed by taking inspiration from the biological skeletal muscle. In this work we used the electrospinning technique to develop a hierarchically arranged nanofibrous structure resembling the morphology and passive biomechanical properties of skeletal muscles. To mimic the passive properties of muscle, a low-modulus polyurethane was used. Several electrospun structures (mats, bundles, and a muscle-like assembly) were produced with different internal 3D arrangements of the nanofibers. A thermal characterization through thermogravimetric and differential scanning calorimetry analysis investigated the physico-chemical properties of the material. The multiscale morphological similarities with the biological counterpart were verified by means of scanning electron microscopy investigation. The tensile tests on the different electrospun samples revealed that the muscle-like assembly presented slightly higher strength and stiffness compared to the skeletal muscle ones. Moreover, mathematical models of the mechanical behavior of the nanofibrous structures were successfully developed, allowing to better investigate the relationships between structure and mechanics of the samples. The promising results suggest the suitability of this hierarchical electrospun nanofibrous structure for applications in regenerative medicine and, if combined with active materials, in soft actuators for robotic.

Understanding the magnetic properties of nanostructures is a field under continuous evolution. Not only the low-dimensional characteristics of the materials confer unique properties to those structures, but also the high degree of freedom when fabricating them increases the possibilities of tailoring their magnetic properties. The recent development of novel technologies that provide ways of both fabrication and characterization at the nanoscale have opened door to the obtainment of nanostructures with specifically designed magnetic properties. In this chapter we have reviewed some of these tailored nanostructures that are sometimes referred to as three-dimensional (3D) nanostructures, such as diameter-modulated nanowires and composition-modulated nanowires. Then, we compare these structures to actual 3D nanostructures, that is, those that take advantage of their design in three spatial dimensions. Finally, we discuss in depth one fascinating 3D self-sustained magnetic nanostructure which has been developed within our research group based on template grown inside 3D tailored alumina, which is obtained using only industrially scalable and highly tunable fabrication methods.

Hierarchical micro/-nanostructures were produced on polycarbonate polymer surfaces by employing a two-step UV-laser processing strategy based on the combination of Direct Laser Interference Patterning (DLIP) of gratings and pillars on the microscale (3 ns, 266 nm, 2 kHz) and subsequently superimposing Laser-induced Periodic Surface Structures (LIPSS, 7&ndash, 10 ps, 350 nm, 100 kHz) which adds nanoscale surface features. Particular emphasis was laid on the influence of the direction of the laser beam polarization on the morphology of resulting hierarchical surfaces. Scanning electron and atomic force microscopy methods were used for the characterization of the hybrid surface structures. Finite-difference time-domain (FDTD) calculations of the laser intensity distribution on the DLIP structures allowed to address the specific polarization dependence of the LIPSS formation observed in the second processing step. Complementary chemical analyzes by micro-Raman spectroscopy and attenuated total reflection Fourier-transform infrared spectroscopy provided in-depth information on the chemical and structural material modifications and material degradation imposed by the laser processing. It was found that when the linear laser polarization was set perpendicular to the DLIP ridges, LIPSS could be formed on top of various DLIP structures. FDTD calculations showed enhanced optical intensity at the topographic maxima, which can explain the dependency of the morphology of LIPSS on the polarization with respect to the orientation of the DLIP structures. It was also found that the degradation of the polymer was enhanced for increasing accumulated fluence levels.

В статье анализируются организационные изменения в экономике России, вызванные коронакризисом. Обосновывается усиление роли иерархических форм организации в условиях нарушения структурной устойчивости социально-экономической системы и «новой нормальности». Анализируются организационные аспекты антикризисной политики в России, показана необходимость восстановления системообразующих от раслей и цепочек производственно-хозяйственных связей на новой антикризисной основе., The article analyzes the organizational changes in Russia’s economy, caused by the coronavirus crisis. The strengthening of the role of hierarchical forms of organization, in conditions of violation of the structural stability of the socio-economic system and of "the new normalcy", is substantiated. The organizational aspects of the anti-crisis policy in Russia are analyzed, the need to restore the backbone industries and chains of production and economic ties on a new anti-crisis basis is shown.

3D printing of fiber‐reinforced composites is expected to be the forefront technology for the next‐generation high‐strength, high‐toughness, and lightweight structural materials. The intrinsic architecture of 3D‐printed composites closely represents biomimetic micro/macrofibril‐like hierarchical structure composed of intermediate filament assembly among the micron‐sized reinforcing fibers, and thus contributes to a novel mechanism to simultaneously improve mechanical properties and structural features. Notably, it is found that an interfacial heterogeneity between numerous inner interfaces in the hierarchical structure enables an exceptional increase in the toughness of composites. The strong interfacial adhesion between the fibers and matrix, with accompanying the inherently weak interfacial adhesion between intermediate filaments and the resultant interfacial voids, provide a close representation of the toughness behavior of natural architectures relying on the localized heterogeneity. Given the critical embedment length of fiber reinforcement, extraordinary improvement has been attained not only in the strength but also in toughness taking advantage of the synergy effect from the aforementioned nature‐inspired features. Indeed, the addition of a small amount of short fiber to the brittle bio‐filaments results in a noticeable increase of more than 200% in the tensile strength and modulus with further elongation increment. This article highlights the inherent structural hierarchy of 3D‐printed composites and the relevant sophisticated mechanism for anomalous mechanical reinforcement., Here, the authors present that the intrinsic architecture of 3D‐printed composites closely represents biomimetic hierarchical structure composed of intermediate filament assembly among the reinforcing fibers, and thus contribute to a novel mechanism to simultaneously improve mechanical properties and structural features. Notably, the authors find that an interfacial heterogeneity between numerous inner interfaces in the hierarchical structure enables an exceptional increase in the toughness of composites.

The rise in structural performance requirements in engineering is driving the research and development of stronger, stiffer, and lighter materials. However, most traditional artificial materials are unable to meet the needs of modern industrial and technological development. In fact, multifarious creatures in nature are further ahead in their use of structural materials. There is a fairly limited selection of natural structural materials at ambient temperatures. They usually consist of hard and soft phases arranged in a complex hierarchy with characteristic dimensions ranging from nanoscale to macroscale. The resulting materials usually show a nearly perfect combination of strength and toughness integrated with lightweight characteristics. This is exactly what is required of engineering materials. In this review, different biological materials were divided into the following types in terms of structural elements: 1D fibrous structures, 2D layered structures, 3D cellular structures and heterogeneous interface structures. For each structural element, corresponding structure components and mechanical properties of typical organisms were well described. Abundant sophisticated models of natural biological structures were discussed contrastively. The purpose of this review was to summarize the excellent properties of multi-dimensional biological models with cross-scale features and to reveal the relationship between structure characteristics and function mechanism, which could provide valuable references for the design and optimization of a future biomimetic composite with high mechanical performance. This review is anticipated to not only inspire novel biomimetic design but also offer a window for the deep understanding of existing outstanding structural composites in diversified species, which could provide continuous innovative power for composite renovation in many engineering fields.

Computational design of menu systems has been solved in limited cases such as the linear menu (list) as an assignment task, where commands are assigned to menu positions while optimizing for for users selection performance and distance of associated items. We show that this approach falls short with larger, hierarchically organized menu systems, where one must also take into account how users navigate hierarchical structures. This paper presents a novel integer programming formulation that models hierarchical menus as a combination of the exact set covering problem and the assignment problem. It organizes commands into ordered groups of ordered groups via a novel objective function based on information foraging theory. It minimizes, on the one hand, the time required to select a command whose location is known from previous usage and, on the other, the time wasted in irrelevant parts of the menu while searching for commands whose location is not known. The convergence of these two factors yields usable, well-ordered command hierarchies from a single model. In generated menus, the lead (first) elements of a group or tab are good indicators of the remaining contents, thereby facilitating the search process. In a controlled usability evaluation, the performance of computationally designed menus was 25 faster than existing commercial designs with respect to selection time. The algorithm is efficient for large, representative instances of the problem. We further show applications in personalization and adaptation of menu systems., Comment: 22 pages paper. 6 pages appendix. 12 Figures

Purpose This paper aims to apply an integrated data envelopment analysis (DEA) and analytic hierarchy process (AHP) approach to a multi-hierarchy grey relational analysis (GRA) model. Consistent with the most real-life applications, the authors focus on a two-level hierarchy in which the attributes of similar characteristics can be grouped into categories. Nevertheless, the proposed approach can be easily extended to a three-level hierarchy in which attributes might also belong to different sub-categories and further be linked to categories. Design/methodology/approach The procedure of incorporating the DEA and AHP methods in a two-level GRA may be broken down into a series of steps. The first three steps are under the heading of attributes and the latter three steps are under the heading of categories as follows: computing the grey relational coefficients of attributes for each alternative using the basic GRA model which further provides the required (output) data for an additive DEA model; computing the priority weights of attributes and categories using the AHP method which provides a priori information on the adjustments of attributes and categories in additive DEA models; computing the grey relational grades of attributes in each category for alternatives using an additive DEA model; converting the grey relational grades of attributes to the grey relational coefficients of categories; computing the grey relational grades of categories for alternatives using an additive DEA model; computing the dissimilarity grades of categories for the tied alternatives using an additive DEA exclusion model. Findings The proposed approach provides a more reasonable and encompassing measure of performance in a hierarchy GRA, based on which the overall ranking position of alternatives is obtained. A case study of a wastewater treatment technology selection verifies the effectiveness of this approach. Originality/value This research is a step forward to overcome the current shortcomings in a hierarchy GRA by extracting the benefits from both the objective and subjective weighting methods.

The formation of micropatterns combining nanostructured (porous) Si (NPSi) and bulk Si is induced by a sequential process of selective high energy ion irradiation and anodic etching. In this work, we investigate the microstructural origin of the increase of Si resistivity on irradiated areas, which is responsible for the inhibition of NPSi formation upon anodization. The increase of Si resistivity after irradiation at variable fluence has been evidenced from current voltage (I-V) characteristics. Microstructural aspects of the Si interfaces irradiated with 1.5–20 MeV Si ions have been revealed by elastic backscattering experiments in channeling configuration, Raman spectroscopy and high resolution transmission electron microscopy. It is concluded that inhibition of NPSi formation is induced at fluences that do not imply amorphization. In fact, the analysis of electrochemical capacitance-voltage measurements suggests that, at fluences well below the threshold for lattice disruption, the concentration of holes suffers from a drastic decrease at depths that match the location of maximum damage yield of the implanted Si ions. These results suggest that the mechanism responsible of formation of hierarchical Si structures is the local B dopant deactivation in the irradiated areas.https://doi.org/10.1016/j.vacuum.2016.10.011, This research was partially funded through grant MAT2014-54826- C2-1- R from Ministerio de Economía y Competitividad.

We demonstrate exceptionally large modulation of PL intensity in hierarchical titanium dioxide (TiO2) nanostructures exposed to molecular oxygen (O2). Optical responsivities up to about 1100% at 20% O2 concentrations are observed in hyperbranched anatase-phase hierarchical structures, outperforming those obtainable by commercial TiO2 nanopowders (up to a factor of ∼7 for response to synthetic air) and significantly improving the ones typically reported in PL-based opto-chemical gas sensing using MOXs. The improved PL response is discussed in terms of the specific morphology of hierarchical structures, characterized by simultaneous presence of small nanoparticles, large surface areas, and large voids. These characteristics guarantee an optimal interplay between photogenerated charges, PL-active centers, and adsorbed gas molecules. The results highlight the potentialities offered by hierarchical structures based on TiO2 or other MOXs and open interesting scenarios toward the development of all-optical and/or hybrid (opto/electrical) chemical sensors with improved sensitivity.

Global climate changes and the aroused environmentally-energy problems categorically moved the research efforts towards programmed processing of a novel class of hierarchical materials having well defined phase, compositional and morphological features. The synthesis based on the principles of the molecular design and integrative chemistry which includes the innovative aerosol and hydro(solvo)thermal nanotechnology routes, the building block assembling and hybridization, represent intelligent platform for the creation of advanced functional materials. Due to exceptional optical properties and a diverse application in electronics, optoelectronics, energy conversion/storage and biomedicine, the examples from some wide band gap oxides for light harvesting and photocatalytic applications as well as both down and up-conversion energy-saving luminescent materials for photonic and biological applications are considered. With the help of various analyzing techniques like XRPD (X-ray powder diffraction), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), analytical and high resolution transmission electron microscopy (TEM, HR-TEM), selected area electron diffraction (SAED), scanning tunneling electron microscopy (STEM), Fourier transform infrared (FTIR) and Raman spectroscopy, photocatalytic and fluorescence measurements, the opportunities of the aerosol and hydro(solvo)thermal routes for the synthesis of novel hierarchically and hybrid assembled structures and nanocomposites are reviewed highlighting the recent research activities realized in the Institute of Technical Sciences of SASA, Belgrade, Serbia and University Carlos III, Madrid, Spain. The morphological, structural and functional aspects of the following systems: ZnO, TiO2, Y2O3:Eu,Yb/Er/T/Hm, Y2O3:Eu@Ag, (Y1−xGdx)2O3:Eu, (NaYF4:Yb/Er)@EDTA/PEG/PVP, are discussed from the state-of-the art and literature contexts. Controlled growth of 1D and 3D hierarchical structures based on the single-source processing methodology in combination with the homogeneous precipitation of optically active intermediate precursor are especially stressed for the case of yttria based phosphor particles and phase-dependent luminescence efficiency. The obtained results offer possible routes for the synthesis of hierarchically structured nanomaterials with tunable structure, morphology and optical properties., The authors acknowledge the financial support from the Ministry of Education, Science and Technological Development, Republic of Serbia (Projects OI172035, OI 1612046, III 45020) and the GEOMATERIALES II program (S2013/MIT-2914).

The direct assembly of functional nanoparticles into a highly crystalline mesoporous semiconductor with oriented configurations is challenging but of significance. Herein, an evaporation induced oriented co‐assembly strategy is reported to incorporate SnO2 nanocrystals (NCs) into a 3D branched mesoporous TiO2 framework by using poly(ethylene oxide)‐block‐polystyrene (PEO‐b‐PS) as the template, SnO2 NCs as the direct tin source, and titanium butoxide (TBOT) as the titania precursor. Owing to the combined properties of ultrasmall particle size (3–5 nm), excellent dispersibility and presence of abundant hydroxyl groups, SnO2 NCs can easily interact with PEO block of the template through hydrogen bonding and co‐assemble with hydrolyzed TBOT to form a novel hierarchical branched mesoporous structure (SHMT). After calcination, the obtained composites exhibit a unique 3D flower‐like structure, which consists of numerous mesoporous rutile TiO2 branches with uniform cylindrical mesopores (≈9 nm). More importantly, the SnO2 NCs are homogeneously distributed in the mesoporous TiO2 matrix, forming numerous n–n heterojunctions. Due to the unique textual structures, the SHMT‐based gas sensors show excellent gas sensing performance with fast response/recovery dynamics, high sensitivity, and selectivity toward ethanol., A solvent evaporation induced oriented co‐assembly strategy is developed to directly incorporate SnO2 nanocrystals into a hierarchical branched mesoporous TiO2 nanostructure (SHMT). Owing to the unique properties such as high specific surface area and numerous TiO2–SnO2 heterojunctions, the SHMT exhibits an excellent ethanol sensing performance, including high sensitivity, fast response/recovery time, and great selectivity.

The development of highly biomimetic scaffolds in terms of composition and structures, to repair or replace damaged bone tissues, is particularly relevant for tissue engineering. This paper investigates a 3D printed porous scaffold containing aligned multi-walled carbon nanotubes (MWCNTs) and nano-hydroxyapatite (nHA), mi- micking the natural bone tissue from the nanoscale to macroscale level. MWCNTs with similar dimensions as collagen fibres are coupled with nHA and mixed within a polycaprolactone (PCL) matrix to produce scaffolds using a screw-assisted extrusion-based additive manufacturing system. Scaffolds with different material com- positions were extensively characterised from morphological, mechanical and biological points of views. Transmission electron microscopy and polarised Raman spectroscopy confirm the presence of aligned MWCNTs within the printed filaments. The PCL/HA/MWCNTs scaffold are similar to the nanostructure of native bone and shows overall increased mechanical properties, cell proliferation, osteogenic differentiation and scaffold mi- neralisation, indicating a promising approach for bone tissue regeneration.

© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Self-assembly is a very effective and popular method to create monolayers or thin films of aligned nanorods and ellipsoids. Nevertheless, there has been little attention to forming thick films of aligned nanorods using this approach. Here, the self-assembly mechanism of nanorods coated with reduced graphene oxide in thick films with both a surface and a bulk alignment process is underpinned. The alignment method is robust and results in films with up to 50% higher volumetric density compared to nonaligned films of the same material. To optimize the coating process, an image processing script is implemented that quantifies the quality of the alignment based on a fast Fourier transform of nanorod electron microscope images. Based on this analysis, parameters are identified that influence the alignment to optimize the process for obtaining large area domains. Finally, dip-coating, blade casting and zone coating are tested and compared and lithographically patterned substrates are used to template the self-assembly process.

The coupling of phonons to electrons and other phonons plays a defining role in material properties, such as charge and energy transport, light emission, and superconductivity. In atomic solids, phonons are delocalized over the 3D lattice, in contrast to molecular solids where localized vibrations dominate. Here, a hierarchical semiconductor that expands the phonon space by combining localized 0D modes with delocalized 2D and 3D modes is described. This material consists of superatomic building blocks (Re6 Se8 ) covalently linked into 2D sheets that are stacked into a layered van der Waals lattice. Using transient reflectance spectroscopy, three types of coherent phonons are identified: localized 0D breathing modes of isolated superatom, 2D synchronized twisting of superatoms in layers, and 3D acoustic interlayer deformation. These phonons are coupled to the electronic degrees of freedom to varying extents. The presence of local phonon modes in an extended crystal opens the door to controlling material properties from hierarchical phonon engineering.

Magnesium-based implants present several advantages for clinical applications, in particular due to their biocompatibility and degradability. However, degradation products can affect negatively the cell activity. In this work, a combined coating strategy to control the implant degradation and cell regulation processes is evaluated, including plasma electrolytic oxidation (PEO) that produces a 13 µm-thick Ca, P, and Si containing ceramic coating with surface porosity, and breath figures (BF) approach that produces a porous polymeric poly(ε-caprolactone) surface. The degradation of PCL-PEO-coated Mg hierarchical scaffold can be tailored to promote cell adhesion and proliferation into the porous structure. As a result, cell culture can colonize the inner PEO-ceramic coating structure where higher amount of bioelements are present. The Mg/PEO/PCL/BF scaffolds exhibit equally good or better premyoblast cell adhesion and proliferation compared with Ti CP control. The biological behavior of this new hierarchical functionalized scaffold can improve the implantation success in bone and cardiovascular clinical applications., This work was funded by ADITIMAT-CM Programme (S2018/NMT-4411) via Regional Government of Madrid and EU Structural Funds. A.S.-C. is grateful to Regional Government of Madrid and European Social Fund for financial support (PEJD-2018-POST/BMD-9592). The authors gratefully acknowledge financial support from the Spanish National Science Foundation (CSIC) and the Ministerio de Ciencia, Innovación y Universidades grant number MAT2016-78437-R, FONDOS FEDER

The main task of this article is providing a sketch of possible approaches, response attempts, conundrums and issues arising from the question: ‘What is a geographical entity?’. It is shown how trying to answer this question is made particularly difficult by a multiplicity of aspects that might be summarized as follows: (1) There exist multiple conceptualizations of the geographical world. (2) Different languages and cultures may slice such a world in different ways. (3) The geographical world has changed and will change over time. (4) Also geography (as a discipline) has changed and will change over time, modifying its perspective, tools, domains of investigation and aims. Consequently, what had, has been, will be considered as non-geographic could be considered as geographic and vice versa. (5) There were, are and will be different kinds of geographies as well as different geographical branches, each of them had, have and might have different tools, aims, points of view and vocabularies. (6) The introduction of new scholarly fields and new technologies, the birth of intellectual movements or paradigm shifts and developments on other disciplinary contexts can/will influence geography as a discipline.

Developing novel anode materials containing electroactive heterostructures which boost ion and charge transfer kinetics in a carbon matrix is still a great challenge. Here we report on a new smartly designed material: SnS2/SnS p-n heterostructures embedded in S,N-doped carbon layer supported by hollow carbon spheres (C@SnSx@C) by a facile method and applied as negative electrode material in sodium ion batteries. The C@SnSx@C2 (at optimized carbon ratio) negative electrode can deliver an initial reversible capacity of 636.5 mAh·g−1 at 0.1 A·g−1, superior rate capability (265.1 mAh·g−1 at rate of 10.0 A·g−1) and long cycle life (capacity retention of 96.3 % at 1.0 A·g−1 after 150 cycles). The SnS2/SnS p-n heterojunctions provide a lower sodium ion diffusion energy barrier (0.38 eV), higher Na+ adsorption energy (−4.66 eV) and higher electronic conductivity due to an internal electric field according to density functional theory calculations compared to plain SnS. Moreover, S,N-doped carbon facilitates electronic conductivity and buffers the volume changes during the conversion reaction-based SnSx upon sodium insertion and extraction process. Porous hollow carbon spheres contribute to prevent the agglomeration of SnS2/SnS nanosheets and keep the structural integrity. Our findings on this unique material might be extended to other ion battery technologies.

Cellular structures (CSs) have been used extensively in recent years, as they offer a unique range of design freedoms. They can be deployed to create parts that can be lightweight by introducing controlled porous features, while still retaining or improving their mechanical, thermal, or even vibrational properties. Recent advancements in additive manufacturing (AM) technologies have helped to increase the feasibility and adoption of cellular structures. The layer-by-layer manufacturing approach offered by AM is ideal for fabricating CSs, with the cost of such parts being largely independent of complexity. There is a growing body of literature concerning CSs made via AM; this presents an opportunity to review the state-of-the-art in this domain and to showcase opportunities in design and manufacturing. This review will propose a novel way of classifying cellular structures by isolating their Geometrical Degrees of Freedom (GDoFs) and will explore the recent innovations in additively manufactured CSs. Based on the present work, the design inputs that are common in CSs generation will be highlighted. Furthermore, the work explores examples of how design inputs have been used to drive the design domain through various case studies. Finally, the review will highlight the manufacturability limitations of CSs in AM.

A facile route to hierarchically organized multicompartmentalized proteinosomes based on a recursive Pickering emulsion procedure using amphiphilic protein–polymer nanoconjugate building blocks is described. The number of incarcerated guest proteinosomes within a single host proteinosome is controlled, and enzymes and genetic polymers encapsulated within targeted subcompartments to produce chemically organized multi-tiered structures. Three types of spatiotemporal response—retarded concomitant release, synchronous release or hierarchical release of dextran and DNA—are demonstrated based on the sequential response of the host and guest membranes to attack by protease, or through variations in the positioning of disulfide-containing cross-links in either the host or guest proteinosomes integrated into the nested architectures. Overall, our studies provide a step towards the construction of hierarchically structured synthetic protocells with chemically and spatially integrated proto-organelles.

We introduce a new type of hybrid material: a nanostructured elastomer covered by a hard photoactive metal-oxide thin film resembling the exoskeleton of insects. It has extreme water repellency and fast self-recovery after damage. A new fabrication method for replicating high aspect ratio, hierarchical re-entrant aluminum structures into polydimethylsiloxane (PDMS) is presented. The method is based on a protective titania layer deposited by atomic layer deposition (ALD) on the aluminum template. The ALD titania transfers to the elastomeric scaffold via sacrificial release etching. The sacrificial release method allows for high aspect ratio, even 100 μm deep and successful release of overhanging structures, unlike conventional peeling. The ALD titania conformally covers the 3D multihierarchical structures of the template and protects the polymer during the release etch. Afterwards it prevents the high aspect ratio nanostructures from elasticity based collapse. The resulting nanostructured hybrid PDMS/titania replicas display robust superhydrophobicity without any further fluoro-coating or modification. Their mechanical and thermal robustness results from a thick nanostructured elastomeric layer which is conformally covered by ceramic titania instead of a monolayer hydrophobic coating. We have demonstrated the durability of these replicas against mechanical abrasion, knife scratches, rubbing, bending, peel tape test, high temperature annealing, UV exposure, water jet impingement and long term underwater storage. Though the material loses its superhydrophobicity in oxygen plasma exposure, a fast recovery from superhydrophilic to superhydrophobic can be achieved after 20 min UV irradiation. UV-assisted recovery is correlated with the high photoactivity of ALD titania film. This novel hybrid material will be applicable to the large area superhydrophobic surfaces in practical outdoor applications.

Mechanical properties of hydrogels can be modified by the variation of structure and concentration of reactive building blocks. One promising biological source for the synthesis of biocompatible hydrogels is fibrinogen. Fibrinogen is a glycoprotein in blood, which can be transformed enzymatically to fibrin playing an important role in wound healing and clot formation. In the present work, it is demonstrated that hybrid hydrogels with their improved mechanical properties, tunable internal structure, and enhanced resistance to degradation can be synthesized by a combination of fibrinogen and reactive amphiphilic copolymers. Water-soluble amphiphilic copolymers with tunable molecular weight and controlled amounts of reactive epoxy side groups are used as reactive crosslinkers to reinforce fibrin hydrogels. In the present work, copolymers that can influence the mechanical properties of fibrin-based hydrogels are used. The reactive copolymers increase the storage modulus of the hydrogels from 600 Pa to 30 kPa. The thickness of fibrin fibers is regulated by the copolymer concentration. It could be demonstrated that the fibrin-based hydrogels are biocompatible and support cell proliferation. Their degradation rate is considerably slower than that of native fibrin gels. In conclusion, fibrin-based hydrogels with tunable elasticity and fiber thickness useful to direct cell responses like proliferation and differentiation are produced. �� 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

The creation of a hierarchical interface between the carbon fiber (CF) and the epoxy resin matrix of fiber-reinforced polymer (CFRP) composites has become an effective strategy for introducing multifunctional properties. Although the efficacy of many hierarchical interfaces has been established in lab-scale, their production is not amenable to high-volume, continuous, cost effective fiber production, which is required for the large-scale commercialization of composites. This work investigates the use of commercially available CO2 laser as a means of nano-structuring the surface of carbon fiber (CF) tows in an incessant throughput procedure. Even though the single carbon fiber tensile strength measurements showed a decrease up to 68% for the exposed CFs, the electrical conductivity exhibited an increment up to 18.4%. Furthermore, results on laminates comprised of irradiated unidirectional CF cloth, demonstrated an enhancement in out of plane electrical conductivity up to 43%, while preserved the Mode-I interlaminar fracture toughness of the composite, showing the potential for multifunctionality. This work indicates that the laser-induced graphitization of the CF surface can act as an interface for fast and cost-effective manufacturing of multifunctional CFRP composite materials.

Nanoimprinting is a well-established replication technology for optical elements, with the capability to replicate highly complex micro- and nanostructures. One of the main challenges, however, is the generation of the master structures necessary for stamp fabrication. We used UV-based Nanoimprint Lithography to prepare hierarchical master structures. To realize structures with two different length scales, conventional nanoimprinting of larger structures and conformal reversal nanoimprinting to print smaller structures on top of the larger structures was performed. Liquid transfer imprint lithography proved to be well suited for this purpose. We used the sample prepared in such a way as a master for further nanoimprinting, where the hierarchical structures can then be imprinted in one single nanoimprinting step. As an example, we presented a diffusor structure with a diffraction-grating structure on top.

Power transformer is one of the critical and expensive apparatus in high voltage power system. Hence, using highly efficient gas sensors to real-time monitor the fault characteristic gases dissolved in transformer oil is in pressing need to ensure the smooth functionalization of the power system. Till date, as a semiconductor metal oxide, zinc oxide (ZnO) is considered as the promising resistive-type gas sensing material. However, the elevated operating temperature, slow response, poor selectivity and stability limit its extensive applications in the field of dissolved gases monitoring. In this respect, rigorous efforts have been made to offset the above-mentioned shortcomings by multiple strategies. In this review, we first introduce the various ZnO hierarchical structures which possess high surface areas and less aggregation, as well as their corresponding gas sensing performances. Then, the primary parameters (sensitivity, selectivity and stability) which affect the performances of ZnO hierarchical structures based gas sensors are discussed in detail. Much more attention is particularly paid to the improvement strategies of enhancing these parameters, mainly including surface modification, additive doping and ultraviolet (UV) light activation. We finally review gas sensing mechanism of ZnO hierarchical structure based gas sensor. Such a detailed study may open up an avenue to fabricate sensor which achieve high sensitivity, good selectivity and long-term stability, making it a promising candidate for transformer oil monitor.

© 2018 The Authors. Helvetica Chimica Acta Published by Wiley-VHCA AG. The self-assembly of molecular inorganic/organic hybrid building blocks into ordered hierarchical nanomaterials with a tunable morphology is an enormous challenge. Here, we describe the synthesis and characterization of a novel liquid crystalline hydrogen-bonding hepta(dimethylsiloxane) azobenzene carboxylic acid dimer. This inorganic/organic hybrid dimer forms sub-5 nm lamellar features in the bulk and at the liquid solid interface. When mixed with a complementary hydrogen-bonding disk-shaped small molecule, a columnar hexagonal phase is formed. When adding a block copolymer containing hydrogen bond-accepting moieties, a hierarchical nanostructured material is obtained with a hexagonal columnar arrangement perpendicular to lamellae super structure. Our supramolecular approach shows that hierarchical hybrid nanomaterials can be fabricated with controlled properties which is appealing for applications such as nanoporous materials, organic electronics, and nanolithography. ispartof: HELVETICA CHIMICA ACTA vol:101 issue:10 status: published