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2,489 result(s) for "hierarchical structure"
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Synthesis of Pd-Doped SnO2 and Flower-like Hierarchical Structures for Efficient and Rapid Detection of Ethanolamine
In this study, we successfully synthesized a Pd-doped SnO2 (Pd-SnO2) material with a flower-like hierarchical structure using the solvothermal method. The material’s structural proper-ties were characterized employing techniques such as XRD, XPS, FESEM and HRTEM. A gas sensor fabricated from the 2.0 mol% Pd-SnO2 material demonstrated exceptional sensitivity (Ra/Rg = 106) to 100 ppm ethanolamine at an operating temperature of 150 °C, with rapid response/recovery times of 10 s and 12 s, respectively, along with excellent linearity, selectivity, and stability, and a detection limit down to 1 ppm. The superior gas-sensing performance is attributed to the distinctive flower-like hierarchical architecture of the Pd-SnO2 and the lattice distortions introduced by Pd doping, which substantially boost the material’s sensing characteristics. Further analysis using density functional theory (DFT) has revealed that within the Pd-SnO2 system, Sn exhibits strong affinities for O and N, leading to high adsorption energies for ethanolamine, thus enhancing the system’s selectivity and sensitivity to ethanolamine gas. This research introduces a novel approach for the efficient and rapid detection of ethanolamine gas.
Fabrication and Photocatalytic Activity of Single Crystalline TiO2 Hierarchically Structured Microspheres
Single crystalline anatase TiO2 microspheres with co-exposed 001/101 facets were prepared by a facile one-pot hydrothermal method using NaF as a morphology controlling agent. The influences of the NaF amount on the morphology and also on the photocatalytic activity were investigated systematically. The obtained microspheres possessed better morphology when the concentration of NaF was chosen at 0.1 mol/L, and the experimental results indicated that the crystal structure and morphology played important roles on the photocatalytic activity, based on the experimental results it was found that the photocatalytic degradation efficiency of TiO2 microspheres on Tetracycline hydrochloride could reach 76.4% in 2 h. Finally, a growth mechanism was proposed by investigating the growth process, i.e., a synergistic effect of F ions modified Ostwald ripening and oriented attachment.
Electrochemical Fabrication of rGO-embedded Ag-TiO2 Nanoring/Nanotube Arrays for Plasmonic Solar Water Splitting
Highlights Reduced graphene oxide (rGO) in electrode can weaken the light scattering of plasmonic Ag nanoparticles and promote the hot electrons transfer from Ag nanoparticles to Ti substrate. A route synergizing rGO with plasmonic Ag on TiO 2 for plasmonic solar water splitting was provided. Effective utilization of hot electrons generated from the decay of surface plasmon resonance in metal nanoparticles is conductive to improve solar water splitting efficiency. Herein, Ag nanoparticles and reduced graphene oxide (rGO) co-decorated hierarchical TiO 2 nanoring/nanotube arrays (TiO 2 R/T) were facilely fabricated by using two-step electrochemical anodization, electrodeposition, and photoreduction methods. Comparative studies were conducted to elucidate the effects of rGO and Ag on the morphology, photoresponse, charge transfer, and photoelectric properties of TiO 2 . Firstly, scanning electron microscope images confirm that the Ag nanoparticles adhered on TiO 2 R/T and TiO 2 R/T-rGO have similar diameter of 20 nm except for TiO 2 R-rGO/T. Then, the UV–Vis DRS and scatter spectra reveal that the optical property of the Ag-TiO 2 R/T-rGO ternary composite is enhanced, ascribing to the visible light absorption of plasmonic Ag nanoparticles and the weakening effect of rGO on light scattering. Meanwhile, intensity-modulated photocurrent spectroscopy and photoluminescence spectra demonstrate that rGO can promote the hot electrons transfer from Ag nanoparticles to Ti substrate, reducing the photogenerated electron–hole recombination. Finally, Ag-TiO 2 R/T-rGO photoanode exhibits high photocurrent density (0.98 mA cm −2 ) and photovoltage (0.90 V), and the stable H 2 evolution rate of 413 μL h −1 cm −2 within 1.5 h under AM 1.5 which exceeds by 1.30 times than that of pristine TiO 2 R/T. In line with the above results, this work provides a reliable route synergizing rGO with plasmonic metal nanoparticles for photocatalysis, in which, rGO presents a broad absorption spectrum and effective photogenerated electrons transfer.
Air Trapping Mechanism in Artificial Salvinia-Like Micro-Hairs Fabricated via Direct Laser Lithography
Salvinia leaves represent an extraordinary example of how nature found a strategy for the long term retainment of air, and thus oxygen, on a surface, the so-called ‘Salvinia effect’, thanks to the peculiar three-dimensional and hierarchical shape of the hairs covering the leaves. Here, starting from the natural model, we have microfabricated hairs inspired by those present on the Salvinia molesta leaves, by means of direct laser lithography. Artificial hairs, like their natural counterpart, are composed of a stalk and a crown-like head, and have been reproduced in the microscale since this ensures, if using a proper design, an air-retaining behavior even if the bulk structural material is hydrophilic. We have investigated the capability of air retainment inside the heads of the hairs that can last up to 100 h, demonstrating the stability of the phenomenon. For a given dimension of the head, the greater the number of filaments, the greater the amount of air that can be trapped inside the heads since the increase in the number of solid–air interfaces able to pin the liquid phase. For this reason, such type of pattern could be used for the fabrication of surfaces for controlled gas retainment and gas release in liquid phases. The range of applications would be quite large, including industrial, medical, and biological fields.
Über die konstruktion einer hierarchischen textverbundgesamtstruktur. Ein beitrag zur theorie der wörterbuchform
Nach einem kurzen kritischen Einblick in die Forschung zu Textver-bundgesamtstrukturen in den Jahren 1988 bis 2016 wird zunächst ein Ausschnitt aus einer Typolo-gie von Textverbundtypen und hierarchischen Textverbundstrukturen präsentiert und kommen-tiert. Nach einer terminologischen Erörterung, insbesondere zum Begriff der lexikographischen Konstituente, wird als Beispiel eine hierarchische Textverbundgesamtstruktur mit rechtserweiterter Textverbundstruktur so schrittweise konstruiert, dass ihre Teilstrukturen, nämlich die hierar-chische rechtserweiterte Textverbundkonstituentenstruktur, ihre hierarchische konstituentenlose Vor- und Nachspannstruktur, ihre hierarchische Wörterverzeichnisstruktur und ihre hierarchische Artikeltextstrukturen getrennt konstruiert und dann zusammengefügt werden. In diesem Prozess werden eine Reihe neuer Begriffe geprägt und zugehörige Termini eingeführt, wie z.B. Vor- und Nachspannsektor, hybride Vor- und Nachspannkonstituente, vorderer Vorspann und hinterer Nachspann. Weiterhin wird überlegt, da Wörterbücher und Gebrauchsgegenstände mit lexikographischen Formeigenschaften immer mindestens eine äuηere Zugriffsstruktur aufweisen, ob und wie wenig-stens äuηere alphabetische Hauptzugriffsstrukturen bei der Konstruktion von hierarchischen Text-verbundgesamtstrukturen berücksichtigt werden können. Dazu wird abschlieηend ein Vorschlag gemacht. On the Construction of a Hierarchical Comprehensive Text Com-pound Structure. A Contribution to the Theory of Dictionary Structures. After a brief critical look at research on comprehensive text compound structures in the period 1988 to 2016 an excerpt of a typology of types of text compounds and hierarchical text compound struc-tures is presented and commented on. Following a terminological discussion, especially regarding the concept of lexicographic constituents, a hierarchical comprehensive text compound structure with right expanded text compound structure is constructed as an example step by step, in such a way that its partial structures, i.e. the hierarchical right expanded text compound constituent structure, its hierarchical constituentless front and back matter structure, its hierarchical word list structure and its hierarchical article stretch structures, are constructed separately and are then combined. In this process a number of new concepts are coined and relevant terms are introduced, e.g. front and back matter sector, hybrid front and back matter constituents, front front matter and back back matter. In addition, because dictionaries and utility objects with lexicographical structural features always display at least one outer access structure, it is considered if and how at least outer alphabetical main access structures can be considered in the construction of hierarchical compre-hensive text compound structures. In conclusion a proposal is made in this regard.
Hierarchical design of FeCo-based microchains for enhanced microwave absorption in C band
Microwave absorbing materials (MAMs) has been intensively investigated in order to meet the requirement of electromagnetic radiation control, especially in S and C band. In this work, FeCo-based magnetic MAMs are hydrothermally synthesized via a magnetic-field-induced process. The composition and morphology of the MAMs are capable of being adjusted simultaneously by the atomic ratio of Fe 2+ to Co 2+ in the precursor. The hierarchical magnetic microchain, which has a core-shell structure of two-dimensional Fe x Co 1− x OOH nanosheets anchored vertically on the surface of a one-dimensional (1D) Co microchain, shows significantly enhanced microwave absorption in C band, resulting in a reflection loss ( R L ) of lower than −20 dB at frequencies ranging from 4.4 to 8.0 GHz under a suitable matching thickness. The magnetic coupling of Co microcrystals and the double-loss mechanisms out of the core-shell structure are considered to promote the microwave attenuation capability. The hierarchical design of 1D magnetic MAMs provides a feasible strategy to solve the electromagnetic pollution in C band.
TreeSummarizedExperiment: a S4 class for data with hierarchical structure version 1; peer review: 2 approved, 1 approved with reservations
Data organized into hierarchical structures (e.g., phylogenies or cell types) arises in several biological fields. It is therefore of interest to have data containers that store the hierarchical structure together with the biological profile data, and provide functions to easily access or manipulate data at different resolutions. Here, we present TreeSummarizedExperiment, a R/S4 class that extends the commonly used SingleCellExperiment class by incorporating tree representations of rows and/or columns (represented by objects of the phylo class). It follows the convention of the SummarizedExperiment class, while providing links between the assays and the nodes of a tree to allow data manipulation at arbitrary levels of the tree. The package is designed to be extensible, allowing new functions on the tree (phylo) to be contributed. As the work is based on the SingleCellExperiment class and the phylo class, both of which are popular classes used in many R packages, it is expected to be able to interact seamlessly with many other tools.
Hierarchical structures of amorphous solids characterized by persistent homology
This article proposes a topological method that extracts hierarchical structures of various amorphous solids. The method is based on the persistence diagram (PD), a mathematical tool for capturing shapes of multiscale data. The input to the PDs is given by an atomic configuration and the output is expressed as 2D histograms. Then, specific distributions such as curves and islands in the PDs identify meaningful shape characteristics of the atomic configuration. Although the method can be applied to a wide variety of disordered systems, it is applied here to silica glass, the Lennard-Jones system, and Cu-Zr metallic glass as standard examples of continuous random network and random packing structures. In silica glass, the method classified the atomic rings as short-range and medium-range orders and unveiled hierarchical ring structures among them. These detailed geometric characterizations clarified a real space origin of the first sharp diffraction peak and also indicated that PDs contain information on elastic response. Even in the Lennard-Jones system and Cu-Zr metallic glass, the hierarchical structures in the atomic configurations were derived in a similar way using PDs, although the glass structures and properties substantially differ from silica glass. These results suggest that the PDs provide a unified method that extracts greater depth of geometric information in amorphous solids than conventional methods.
Nacre-like composites with superior specific damping performance
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.
Mesoscale bicontinuous networks in self-healing hydrogels delay fatigue fracture
Load-bearing biological tissues, such as muscles, are highly fatigue-resistant, but how the exquisite hierarchical structures of biological tissues contribute to their excellent fatigue resistance is not well understood. In this work, we study antifatigue properties of soft materials with hierarchical structures using polyampholyte hydrogels (PA gels) as a simple model system. PA gels are tough and self-healing, consisting of reversible ionic bonds at the 1-nm scale, a cross-linked polymer network at the 10-nm scale, and bicontinuous hard/soft phase networks at the 100-nm scale. We find that the polymer network at the 10-nm scale determines the threshold of energy release rate G₀ above which the crack grows, while the bicontinuous phase networks at the 100-nm scale significantly decelerate the crack advance until a transition Gtran far above G₀. In situ small-angle X-ray scattering analysis reveals that the hard phase network suppresses the crack advance to show decelerated fatigue fracture, and Gtran corresponds to the rupture of the hard phase network.