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Sample records for hierarchical structure consisting

  1. Novel nanocomposite hydrogels consisting of layered double hydroxide with ultrahigh tensibility and hierarchical porous structure at low inorganic content.

    Science.gov (United States)

    Hu, Ziqiao; Chen, Guangming

    2014-09-10

    A novel type of polymer nanocomposite (NC) hydrogel with extraordinary mechanical properties at low inorganic content is prepared and investigated. The NC hydrogels consist of isethionate-loaded layered double hydroxide/polyacrylamide (LDH-Ise/PAM) - with LDH-Ise being used because of its swelling properties - and no conventional organic crosslinker. The NC hydrogels exhibit an unusual hierarchical porous structure at the micro- and nanometer scales, and their elongation at break can exceed 4000%.

  2. Hierarchically structured monolithic silicalite-1 consisting of crystallized nanoparticles and its performance in the Beckmann rearrangement of cyclohexanone oxime.

    Science.gov (United States)

    Li, Wen-Cui; Lu, An-Hui; Palkovits, Regina; Schmidt, Wolfgang; Spliethoff, Bernd; Schüth, Ferdi

    2005-09-14

    In this study, we present a synthetic pathway for the fabrication of self-supporting zeolite monoliths consisting of crystallized nanoparticles. A resorcinol-formaldehyde-based organic aerogel is used as a template, and silicalite-1 is used as the zeolite example. The silicalite-1 monoliths obtained consist of individual well-defined zeolite nanocrystals with sizes of 30-40 nm. The monoliths exhibit a high mechanical stability and have hierarchical porosity, with micropores within the zeolite particles, a mesopore system formed by the packing of the nanoparticles, and a macropore system on the monolith level. Such monolithic zeolites show high selectivity typically above 80% to epsilon-caprolactam combined with a high rate of reaction of 0.46 g(caprolactame)/(g(catalyst).h) in the Beckmann rearrangement of cyclohexanone oxime.

  3. Hierarchical Porous Structures

    Energy Technology Data Exchange (ETDEWEB)

    Grote, Christopher John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-07

    Materials Design is often at the forefront of technological innovation. While there has always been a push to generate increasingly low density materials, such as aero or hydrogels, more recently the idea of bicontinuous structures has gone more into play. This review will cover some of the methods and applications for generating both porous, and hierarchically porous structures.

  4. Hierarchically Structured Electrospun Fibers

    Directory of Open Access Journals (Sweden)

    Nicole E. Zander

    2013-01-01

    Full Text Available Traditional electrospun nanofibers have a myriad of applications ranging from scaffolds for tissue engineering to components of biosensors and energy harvesting devices. The generally smooth one-dimensional structure of the fibers has stood as a limitation to several interesting novel applications. Control of fiber diameter, porosity and collector geometry will be briefly discussed, as will more traditional methods for controlling fiber morphology and fiber mat architecture. The remainder of the review will focus on new techniques to prepare hierarchically structured fibers. Fibers with hierarchical primary structures—including helical, buckled, and beads-on-a-string fibers, as well as fibers with secondary structures, such as nanopores, nanopillars, nanorods, and internally structured fibers and their applications—will be discussed. These new materials with helical/buckled morphology are expected to possess unique optical and mechanical properties with possible applications for negative refractive index materials, highly stretchable/high-tensile-strength materials, and components in microelectromechanical devices. Core-shell type fibers enable a much wider variety of materials to be electrospun and are expected to be widely applied in the sensing, drug delivery/controlled release fields, and in the encapsulation of live cells for biological applications. Materials with a hierarchical secondary structure are expected to provide new superhydrophobic and self-cleaning materials.

  5. Detecting Hierarchical Structure in Networks

    DEFF Research Database (Denmark)

    Herlau, Tue; Mørup, Morten; Schmidt, Mikkel Nørgaard;

    2012-01-01

    a generative Bayesian model that is able to infer whether hierarchies are present or not from a hypothesis space encompassing all types of hierarchical tree structures. For efficient inference we propose a collapsed Gibbs sampling procedure that jointly infers a partition and its hierarchical structure......Many real-world networks exhibit hierarchical organization. Previous models of hierarchies within relational data has focused on binary trees; however, for many networks it is unknown whether there is hierarchical structure, and if there is, a binary tree might not account well for it. We propose....... On synthetic and real data we demonstrate that our model can detect hierarchical structure leading to better link-prediction than competing models. Our model can be used to detect if a network exhibits hierarchical structure, thereby leading to a better comprehension and statistical account the network....

  6. Treatment Protocols as Hierarchical Structures

    Science.gov (United States)

    Ben-Bassat, Moshe; Carlson, Richard W.; Puri, Vinod K.; Weil, Max Harry

    1978-01-01

    We view a treatment protocol as a hierarchical structure of therapeutic modules. The lowest level of this structure consists of individual therapeutic actions. Combinations of individual actions define higher level modules, which we call routines. Routines are designed to manage limited clinical problems, such as the routine for fluid loading to correct hypovolemia. Combinations of routines and additional actions, together with comments, questions, or precautions organized in a branching logic, in turn, define the treatment protocol for a given disorder. Adoption of this modular approach may facilitate the formulation of treatment protocols, since the physician is not required to prepare complex flowcharts. This hierarchical approach also allows protocols to be updated and modified in a flexible manner. By use of such a standard format, individual components may be fitted together to create protocols for multiple disorders. The technique is suited for computer implementation. We believe that this hierarchical approach may facilitate standarization of patient care as well as aid in clinical teaching. A protocol for acute pancreatitis is used to illustrate this technique.

  7. Trees and Hierarchical Structures

    CERN Document Server

    Haeseler, Arndt

    1990-01-01

    The "raison d'etre" of hierarchical dustering theory stems from one basic phe­ nomenon: This is the notorious non-transitivity of similarity relations. In spite of the fact that very often two objects may be quite similar to a third without being that similar to each other, one still wants to dassify objects according to their similarity. This should be achieved by grouping them into a hierarchy of non-overlapping dusters such that any two objects in ~ne duster appear to be more related to each other than they are to objects outside this duster. In everyday life, as well as in essentially every field of scientific investigation, there is an urge to reduce complexity by recognizing and establishing reasonable das­ sification schemes. Unfortunately, this is counterbalanced by the experience of seemingly unavoidable deadlocks caused by the existence of sequences of objects, each comparatively similar to the next, but the last rather different from the first.

  8. Hierarchical mutual information for the comparison of hierarchical community structures in complex networks

    CERN Document Server

    Perotti, Juan Ignacio; Caldarelli, Guido

    2015-01-01

    The quest for a quantitative characterization of community and modular structure of complex networks produced a variety of methods and algorithms to classify different networks. However, it is not clear if such methods provide consistent, robust and meaningful results when considering hierarchies as a whole. Part of the problem is the lack of a similarity measure for the comparison of hierarchical community structures. In this work we give a contribution by introducing the {\\it hierarchical mutual information}, which is a generalization of the traditional mutual information, and allows to compare hierarchical partitions and hierarchical community structures. The {\\it normalized} version of the hierarchical mutual information should behave analogously to the traditional normalized mutual information. Here, the correct behavior of the hierarchical mutual information is corroborated on an extensive battery of numerical experiments. The experiments are performed on artificial hierarchies, and on the hierarchical ...

  9. Structural integrity of hierarchical composites

    Directory of Open Access Journals (Sweden)

    Marco Paggi

    2012-01-01

    Full Text Available Interface mechanical problems are of paramount importance in engineering and materials science. Traditionally, due to the complexity of modelling their mechanical behaviour, interfaces are often treated as defects and their features are not explored. In this study, a different approach is illustrated, where the interfaces play an active role in the design of innovative hierarchical composites and are fundamental for their structural integrity. Numerical examples regarding cutting tools made of hierarchical cellular polycrystalline materials are proposed, showing that tailoring of interface properties at the different scales is the way to achieve superior mechanical responses that cannot be obtained using standard materials

  10. Hierarchical Neural Network Structures for Phoneme Recognition

    CERN Document Server

    Vasquez, Daniel; Minker, Wolfgang

    2013-01-01

    In this book, hierarchical structures based on neural networks are investigated for automatic speech recognition. These structures are evaluated on the phoneme recognition task where a  Hybrid Hidden Markov Model/Artificial Neural Network paradigm is used. The baseline hierarchical scheme consists of two levels each which is based on a Multilayered Perceptron. Additionally, the output of the first level serves as a second level input. The computational speed of the phoneme recognizer can be substantially increased by removing redundant information still contained at the first level output. Several techniques based on temporal and phonetic criteria have been investigated to remove this redundant information. The computational time could be reduced by 57% whilst keeping the system accuracy comparable to the baseline hierarchical approach.

  11. Hierarchically Structured Electrospun Fibers

    Science.gov (United States)

    2013-01-07

    range of fluorescence could be tuned from yellow-green to blue , making these fibers ideal for micro- and nano-optoelectronic devices [144]. Figure 7...forces. Rapid phase separation of the distorted droplet and energy minimization may lead to the formation of the spider -web-like structure of the fiber...engineering cellularized blood vessels. Biomaterials 2010, 31, 4313–4321. 59. Thorvaldsson, A.; Stenhamre, H.; Gatenholm, P.; Walkenstrom, P

  12. Hierarchical structure of biological systems

    Science.gov (United States)

    Alcocer-Cuarón, Carlos; Rivera, Ana L; Castaño, Victor M

    2014-01-01

    A general theory of biological systems, based on few fundamental propositions, allows a generalization of both Wierner and Berthalanffy approaches to theoretical biology. Here, a biological system is defined as a set of self-organized, differentiated elements that interact pair-wise through various networks and media, isolated from other sets by boundaries. Their relation to other systems can be described as a closed loop in a steady-state, which leads to a hierarchical structure and functioning of the biological system. Our thermodynamical approach of hierarchical character can be applied to biological systems of varying sizes through some general principles, based on the exchange of energy information and/or mass from and within the systems. PMID:24145961

  13. Electronic Properties in a Hierarchical Multilayer Structure

    Institute of Scientific and Technical Information of China (English)

    ZHU Chen-Ping; XIONG Shi-Jie

    2001-01-01

    We investigate electronic properties of a hierarchical multilayer structure consisting of stacking of barriers and wells. The structure is formed in a sequence of generations, each of which is constructed with the same pattern but with the previous generation as the basic building blocks. We calculate the transmission spectrum which shows the multifractal behavior for systems with large generation index. From the analysis of the average resistivity and the multifractal structure of the wavefunctions, we show that there exist different types of states exhibiting extended, localized and intermediate characteristics. The degree of localization is sensitive to the variation of the structural parameters.Suggestion of the possible experimental realization is discussed.

  14. Modeling hierarchical structures - Hierarchical Linear Modeling using MPlus

    CERN Document Server

    Jelonek, M

    2006-01-01

    The aim of this paper is to present the technique (and its linkage with physics) of overcoming problems connected to modeling social structures, which are typically hierarchical. Hierarchical Linear Models provide a conceptual and statistical mechanism for drawing conclusions regarding the influence of phenomena at different levels of analysis. In the social sciences it is used to analyze many problems such as educational, organizational or market dilemma. This paper introduces the logic of modeling hierarchical linear equations and estimation based on MPlus software. I present my own model to illustrate the impact of different factors on school acceptation level.

  15. Modeling hierarchical structures - Hierarchical Linear Modeling using MPlus

    OpenAIRE

    Jelonek, Magdalena

    2006-01-01

    The aim of this paper is to present the technique (and its linkage with physics) of overcoming problems connected to modeling social structures, which are typically hierarchical. Hierarchical Linear Models provide a conceptual and statistical mechanism for drawing conclusions regarding the influence of phenomena at different levels of analysis. In the social sciences it is used to analyze many problems such as educational, organizational or market dilemma. This paper introduces the logic of m...

  16. Hierarchical structures consisting of SiO2 nanorods and p-GaN microdomes for efficiently harvesting solar energy for InGaN quantum well photovoltaic cells.

    Science.gov (United States)

    Ho, Cheng-Han; Lien, Der-Hsien; Chang, Hung-Chih; Lin, Chin-An; Kang, Chen-Fang; Hsing, Meng-Kai; Lai, Kun-Yu; He, Jr-Hau

    2012-12-07

    We experimentally and theoretically demonstrated the hierarchical structure of SiO(2) nanorod arrays/p-GaN microdomes as a light harvesting scheme for InGaN-based multiple quantum well solar cells. The combination of nano- and micro-structures leads to increased internal multiple reflection and provides an intermediate refractive index between air and GaN. Cells with the hierarchical structure exhibit improved short-circuit current densities and fill factors, rendering a 1.47 fold efficiency enhancement as compared to planar cells.

  17. Hierarchical Structures in Hypertext Learning Environments

    NARCIS (Netherlands)

    Bezdan, Eniko; Kester, Liesbeth; Kirschner, Paul A.

    2011-01-01

    Bezdan, E., Kester, L., & Kirschner, P. A. (2011, 9 September). Hierarchical Structures in Hypertext Learning Environments. Presentation for the visit of KU Leuven, Open University, Heerlen, The Netherlands.

  18. Discovering hierarchical structure in normal relational data

    DEFF Research Database (Denmark)

    Schmidt, Mikkel Nørgaard; Herlau, Tue; Mørup, Morten

    2014-01-01

    Hierarchical clustering is a widely used tool for structuring and visualizing complex data using similarity. Traditionally, hierarchical clustering is based on local heuristics that do not explicitly provide assessment of the statistical saliency of the extracted hierarchy. We propose a non-param...

  19. Hierarchically structured, nitrogen-doped carbon membranes

    KAUST Repository

    Wang, Hong

    2017-08-03

    The present invention is a structure, method of making and method of use for a novel macroscopic hierarchically structured, nitrogen-doped, nano-porous carbon membrane (HNDCMs) with asymmetric and hierarchical pore architecture that can be produced on a large-scale approach. The unique HNDCM holds great promise as components in separation and advanced carbon devices because they could offer unconventional fluidic transport phenomena on the nanoscale. Overall, the invention set forth herein covers a hierarchically structured, nitrogen-doped carbon membranes and methods of making and using such a membranes.

  20. Evaluating Hierarchical Structure in Music Annotations.

    Science.gov (United States)

    McFee, Brian; Nieto, Oriol; Farbood, Morwaread M; Bello, Juan Pablo

    2017-01-01

    Music exhibits structure at multiple scales, ranging from motifs to large-scale functional components. When inferring the structure of a piece, different listeners may attend to different temporal scales, which can result in disagreements when they describe the same piece. In the field of music informatics research (MIR), it is common to use corpora annotated with structural boundaries at different levels. By quantifying disagreements between multiple annotators, previous research has yielded several insights relevant to the study of music cognition. First, annotators tend to agree when structural boundaries are ambiguous. Second, this ambiguity seems to depend on musical features, time scale, and genre. Furthermore, it is possible to tune current annotation evaluation metrics to better align with these perceptual differences. However, previous work has not directly analyzed the effects of hierarchical structure because the existing methods for comparing structural annotations are designed for "flat" descriptions, and do not readily generalize to hierarchical annotations. In this paper, we extend and generalize previous work on the evaluation of hierarchical descriptions of musical structure. We derive an evaluation metric which can compare hierarchical annotations holistically across multiple levels. sing this metric, we investigate inter-annotator agreement on the multilevel annotations of two different music corpora, investigate the influence of acoustic properties on hierarchical annotations, and evaluate existing hierarchical segmentation algorithms against the distribution of inter-annotator agreement.

  1. Evaluating Hierarchical Structure in Music Annotations

    Directory of Open Access Journals (Sweden)

    Brian McFee

    2017-08-01

    Full Text Available Music exhibits structure at multiple scales, ranging from motifs to large-scale functional components. When inferring the structure of a piece, different listeners may attend to different temporal scales, which can result in disagreements when they describe the same piece. In the field of music informatics research (MIR, it is common to use corpora annotated with structural boundaries at different levels. By quantifying disagreements between multiple annotators, previous research has yielded several insights relevant to the study of music cognition. First, annotators tend to agree when structural boundaries are ambiguous. Second, this ambiguity seems to depend on musical features, time scale, and genre. Furthermore, it is possible to tune current annotation evaluation metrics to better align with these perceptual differences. However, previous work has not directly analyzed the effects of hierarchical structure because the existing methods for comparing structural annotations are designed for “flat” descriptions, and do not readily generalize to hierarchical annotations. In this paper, we extend and generalize previous work on the evaluation of hierarchical descriptions of musical structure. We derive an evaluation metric which can compare hierarchical annotations holistically across multiple levels. sing this metric, we investigate inter-annotator agreement on the multilevel annotations of two different music corpora, investigate the influence of acoustic properties on hierarchical annotations, and evaluate existing hierarchical segmentation algorithms against the distribution of inter-annotator agreement.

  2. Quantum transport through hierarchical structures.

    Science.gov (United States)

    Boettcher, S; Varghese, C; Novotny, M A

    2011-04-01

    The transport of quantum electrons through hierarchical lattices is of interest because such lattices have some properties of both regular lattices and random systems. We calculate the electron transmission as a function of energy in the tight-binding approximation for two related Hanoi networks. HN3 is a Hanoi network with every site having three bonds. HN5 has additional bonds added to HN3 to make the average number of bonds per site equal to five. We present a renormalization group approach to solve the matrix equation involved in this quantum transport calculation. We observe band gaps in HN3, while no such band gaps are observed in linear networks or in HN5. We provide a detailed scaling analysis near the edges of these band gaps.

  3. Hierarchical structure of nanofibers by bubbfil spinning

    Directory of Open Access Journals (Sweden)

    Liu Chang

    2015-01-01

    Full Text Available A polymer bubble is easy to be broken under a small external force, various different fragments are formed, which can be produced to different morphologies of products including nanofibers and plate-like strip. Polyvinyl-alcohol/honey solution is used in the experiment to show hierarchical structure by the bubbfil spinning.

  4. Design of Hierarchical Structures for Synchronized Deformations

    Science.gov (United States)

    Seifi, Hamed; Javan, Anooshe Rezaee; Ghaedizadeh, Arash; Shen, Jianhu; Xu, Shanqing; Xie, Yi Min

    2017-01-01

    In this paper we propose a general method for creating a new type of hierarchical structures at any level in both 2D and 3D. A simple rule based on a rotate-and-mirror procedure is introduced to achieve multi-level hierarchies. These new hierarchical structures have remarkably few degrees of freedom compared to existing designs by other methods. More importantly, these structures exhibit synchronized motions during opening or closure, resulting in uniform and easily-controllable deformations. Furthermore, a simple analytical formula is found which can be used to avoid collision of units of the structure during the closing process. The novel design concept is verified by mathematical analyses, computational simulations and physical experiments.

  5. Hierarchical community structure in complex (social) networks

    CERN Document Server

    Massaro, Emanuele

    2014-01-01

    The investigation of community structure in networks is a task of great importance in many disciplines, namely physics, sociology, biology and computer science where systems are often represented as graphs. One of the challenges is to find local communities from a local viewpoint in a graph without global information in order to reproduce the subjective hierarchical vision for each vertex. In this paper we present the improvement of an information dynamics algorithm in which the label propagation of nodes is based on the Markovian flow of information in the network under cognitive-inspired constraints \\cite{Massaro2012}. In this framework we have introduced two more complex heuristics that allow the algorithm to detect the multi-resolution hierarchical community structure of networks from a source vertex or communities adopting fixed values of model's parameters. Experimental results show that the proposed methods are efficient and well-behaved in both real-world and synthetic networks.

  6. Alligator osteoderms: Mechanical behavior and hierarchical structure

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Irene H. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Yang, Wen, E-mail: wey005@eng.ucsd.edu [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Meyers, Marc A. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Departments of Mechanical and Aerospace Engineering and Nanoengineering, University of California, San Diego, La Jolla, CA 92093 (United States)

    2014-02-01

    Osteoderms are bony scutes embedded underneath the dermal layers of the skin acting as a protection of the alligator (Archosauria: Crocodylia) internal organs and tissues. Additionally, these scutes function as an aid in temperature regulation. The scutes are inter-linked by fibrous connective tissue. They have properties similar to bone and thus have the necessary toughness to provide protection against predators. The scutes consist of hydroxyapatite and have a porosity of approximately 12%. They have a disc-like morphology with a ridge along the middle of the plate, called the keel; the outer perimeter of the disc has depressions, grooves, and jagged edges which anchor the collagen and act as sutures. Computerized tomography reveals the pattern of elongated pores, which emanate from the keel in a radial pattern. Micro-indentation measurements along the cross-section show a zigzag behavior due to the porosity. Compression results indicate that the axial direction is the strongest (UTS ∼ 67 MPa) and toughest (11 MJ/m{sup 3}); this is the orientation in which they undergo the largest external compression forces from predator teeth. Toughening mechanisms are identified through observation of the damage progression and interpreted in mechanistic terms. They are: flattening of pores, microcrack opening, and microcrack growth and coalescence. Collagen plays an essential role in toughening and plasticity by providing bridges that impede the opening of the cracks and prevent their growth. - Highlights: • We characterized the hierarchical structure of alligator scute. • The anisotropic mechanical behavior of alligator scute was studied. • Toughening mechanisms were identified at the micro- and nano-levels.

  7. Additive Manufacturing of Hierarchical Porous Structures

    Energy Technology Data Exchange (ETDEWEB)

    Grote, Christopher John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division. Polymers and Coatings

    2016-08-30

    Additive manufacturing has become a tool of choice for the development of customizable components. Developments in this technology have led to a powerful array of printers that t serve a variety of needs. However, resin development plays a crucial role in leading the technology forward. This paper addresses the development and application of printing hierarchical porous structures. Beginning with the development of a porous scaffold, which can be functionalized with a variety of materials, and concluding with customized resins for metal, ceramic, and carbon structures.

  8. The hierarchical structure of chemical engineering

    Institute of Scientific and Technical Information of China (English)

    Mooson; KWAUK

    2007-01-01

    Around the turn of the present century,scholars began to recognize chemical engineering as a com-plex system,and have been searching for a convenient point of entry for refreshing its knowledge base.From our study of the dynamic structures of dispersed particles in fluidization and the resultingmulti-scale method,we have been attempting to extend our findings to structures prevailing in othermultiphase systems as well as in the burgeoning industries producing functional materials.Chemicalengineering itself is hierarchically structured.Besides structures based on space and time,such hier-archy could be built from ChE history scaled according to science content,or from ChE operation ac-cording to the expenditure of manpower and capital investment.

  9. The hierarchical structure of chemical engineering

    Institute of Scientific and Technical Information of China (English)

    Mooson KWAUK

    2007-01-01

    Around the turn of the present century, scholars began to recognize chemical engineering as a complex system, and have been searching for a convenient point of entry for refreshing its knowledge base. From our study of the dynamic structures of dispersed particles in fluidization and the resulting multi-scale method, we have been attempting to extend our findings to structures prevailing in other multiphase systems as well as in the burgeoning industries producing functional materials. Chemical engineering itself is hierarchically structured. Besides structures based on space and time, such hierarchy could be built from ChE history scaled according to science content, or from ChE operation according to the expenditure of manpower and capital investment.

  10. Hierarchical structuring of liquid crystal polymer-Laponite hybrid materials.

    Science.gov (United States)

    Tritschler, Ulrich; Zlotnikov, Igor; Zaslansky, Paul; Aichmayer, Barbara; Fratzl, Peter; Schlaad, Helmut; Cölfen, Helmut

    2013-09-03

    Biomimetic organic-inorganic composite materials were fabricated via one-step self-organization on three hierarchical levels. The organic component was a polyoxazoline with pendent cholesteryl and carboxyl (N-Boc-protected amino acid) side chains that was able to form a chiral nematic lyotropic phase and bind to positively charged inorganic faces of Laponite. The Laponite particles formed a mesocrystalline arrangement within the liquid-crystal (LC) polymer phase upon shearing a viscous dispersion of Laponite nanoparticles and LC polymer in DMF. Complementary analytical and mechanical characterization techniques (AUC, POM, TEM, SEM, SAXS, μCT, and nanoindentation) covering the millimeter, micrometer, and nanometer length scales reveal the hierarchical structures and properties of the composite materials consisting of different ratios of Laponite nanoparticles and liquid-crystalline polymer.

  11. Hierarchical structures in fully developed turbulence

    Science.gov (United States)

    Liu, Li

    Analysis of the probability density functions (PDFs) of the velocity increment dvl and of their deformation is used to reveal the statistical structure of the intermittent energy cascade dynamics of turbulence. By analyzing a series of turbulent data sets including that of an experiment of fully developed low temperature helium turbulent gas flow (Belin, Tabeling, & Willaime, Physica D 93, 52, 1996), of a three-dimensional isotropic Navier-Stokes simulation with a resolution of 2563 (Cao, Chen, & She, Phys. Rev. Lett. 76, 3711, 1996) and of a GOY shell model simulation (Leveque & She, Phys. Rev. E 55, 1997) of a very big sample size (up to 5 billions), the validity of the Hierarchical Structure model (She & Leveque, Phys. Rev. Lett. 72, 366, 1994) for the inertial-range is firmly demonstrated. Furthermore, it is shown that parameters in the Hierarchical Structure model can be reliably measured and used to characterize the cascade process. The physical interpretations of the parameters then allow to describe differential changes in different turbulent systems so as to address non-universal features of turbulent systems. It is proposed that the above study provides a framework for the study of non-homogeneous turbulence. A convergence study of moments and scaling exponents is also carried out with detailed analysis of effects of finite statistical sample size. A quantity Pmin is introduced to characterize the resolution of a PDF, and hence the sample size. The fact that any reported scaling exponent depends on the PDF resolution suggests that the validation (or rejection) of a model of turbulence needs to carry out a resolution dependence analysis on its scaling prediction.

  12. Crack Propagation in Bamboo's Hierarchical Cellular Structure

    Science.gov (United States)

    Habibi, Meisam K.; Lu, Yang

    2014-07-01

    Bamboo, as a natural hierarchical cellular material, exhibits remarkable mechanical properties including excellent flexibility and fracture toughness. As far as bamboo as a functionally graded bio-composite is concerned, the interactions of different constituents (bamboo fibers; parenchyma cells; and vessels.) alongside their corresponding interfacial areas with a developed crack should be of high significance. Here, by using multi-scale mechanical characterizations coupled with advanced environmental electron microscopy (ESEM), we unambiguously show that fibers' interfacial areas along with parenchyma cells' boundaries were preferred routes for crack growth in both radial and longitudinal directions. Irrespective of the honeycomb structure of fibers along with cellular configuration of parenchyma ground, the hollow vessels within bamboo culm affected the crack propagation too, by crack deflection or crack-tip energy dissipation. It is expected that the tortuous crack propagation mode exhibited in the present study could be applicable to other cellular natural materials as well.

  13. Hierarchical structure and biomineralization in cricket tooth

    CERN Document Server

    Xing, Xueqing; Cai, Quan; Mo, Guang; Du, Rong; Chen, Zhongjun; Wu, Zhonghua

    2012-01-01

    Cricket is a truculent insect with stiff and sharp teeth as a fighting weapon. The structure and possible biomineralization of the cricket teeth are always interested. Synchrotron radiation X-ray fluorescence, X-ray diffraction and small angle X-ray scattering techniques were used to probe the element distribution, possible crystalline structures and size distribution of scatterers in cricket teeth. Scanning electron microscope was used to observe the nanoscaled structure. The results demonstrate that Zn is the main heavy element in cricket teeth. The surface of the cricket teeth has a crystalline compound like ZnFe2(AsO4)2(OH)2(H2O)4. While, the interior of the teeth has a crystalline compound like ZnCl2, which is from the biomineralization. The ZnCl2-like biomineral forms nanoscaled microfibrils and their axial direction points at the top of tooth cusp. The microfibrils aggregate random into intermediate filaments, forming a hierarchical structure. A sketch map of the cricket tooth cusp was proposed and a d...

  14. Hierarchical structure of moral stages assessed by a sorting task

    NARCIS (Netherlands)

    Boom, J.; Brugman, D.; Van der Heijden, P.G.M.

    2001-01-01

    Following criticism of Kohlberg’s theory of moral judgment, an empirical re-examination of hierarchical stage structure was desirable. Utilizing Piaget’s concept of reflective abstraction as a basis, the hierarchical stage structure was investigated using a new method. Study participants (553 Dutch

  15. Dynamic and Quantitative Method of Analyzing Service Consistency Evolution Based on Extended Hierarchical Finite State Automata

    Directory of Open Access Journals (Sweden)

    Linjun Fan

    2014-01-01

    Full Text Available This paper is concerned with the dynamic evolution analysis and quantitative measurement of primary factors that cause service inconsistency in service-oriented distributed simulation applications (SODSA. Traditional methods are mostly qualitative and empirical, and they do not consider the dynamic disturbances among factors in service’s evolution behaviors such as producing, publishing, calling, and maintenance. Moreover, SODSA are rapidly evolving in terms of large-scale, reusable, compositional, pervasive, and flexible features, which presents difficulties in the usage of traditional analysis methods. To resolve these problems, a novel dynamic evolution model extended hierarchical service-finite state automata (EHS-FSA is constructed based on finite state automata (FSA, which formally depict overall changing processes of service consistency states. And also the service consistency evolution algorithms (SCEAs based on EHS-FSA are developed to quantitatively assess these impact factors. Experimental results show that the bad reusability (17.93% on average is the biggest influential factor, the noncomposition of atomic services (13.12% is the second biggest one, and the service version’s confusion (1.2% is the smallest one. Compared with previous qualitative analysis, SCEAs present good effectiveness and feasibility. This research can guide the engineers of service consistency technologies toward obtaining a higher level of consistency in SODSA.

  16. Automatic layout of structured hierarchical reports.

    Science.gov (United States)

    Bakke, Eirik; Karger, David R; Miller, Robert C

    2013-12-01

    Domain-specific database applications tend to contain a sizable number of table-, form-, and report-style views that must each be designed and maintained by a software developer. A significant part of this job is the necessary tweaking of low-level presentation details such as label placements, text field dimensions, list or table styles, and so on. In this paper, we present a horizontally constrained layout management algorithm that automates the display of structured hierarchical data using the traditional visual idioms of hand-designed database UIs: tables, multi-column forms, and outline-style indented lists. We compare our system with pure outline and nested table layouts with respect to space efficiency and readability, the latter with an online user study on 27 subjects. Our layouts are 3.9 and 1.6 times more compact on average than outline layouts and horizontally unconstrained table layouts, respectively, and are as readable as table layouts even for large datasets.

  17. Hierarchical Data Structures, Institutional Research, and Multilevel Modeling

    Science.gov (United States)

    O'Connell, Ann A.; Reed, Sandra J.

    2012-01-01

    Multilevel modeling (MLM), also referred to as hierarchical linear modeling (HLM) or mixed models, provides a powerful analytical framework through which to study colleges and universities and their impact on students. Due to the natural hierarchical structure of data obtained from students or faculty in colleges and universities, MLM offers many…

  18. Self-consistent structure of metallic hydrogen

    Science.gov (United States)

    Straus, D. M.; Ashcroft, N. W.

    1977-01-01

    A calculation is presented of the total energy of metallic hydrogen for a family of face-centered tetragonal lattices carried out within the self-consistent phonon approximation. The energy of proton motion is large and proper inclusion of proton dynamics alters the structural dependence of the total energy, causing isotropic lattices to become favored. For the dynamic lattice the structural dependence of terms of third and higher order in the electron-proton interaction is greatly reduced from static lattice equivalents.

  19. Cortical tracking of hierarchical linguistic structures in connected speech.

    Science.gov (United States)

    Ding, Nai; Melloni, Lucia; Zhang, Hang; Tian, Xing; Poeppel, David

    2016-01-01

    The most critical attribute of human language is its unbounded combinatorial nature: smaller elements can be combined into larger structures on the basis of a grammatical system, resulting in a hierarchy of linguistic units, such as words, phrases and sentences. Mentally parsing and representing such structures, however, poses challenges for speech comprehension. In speech, hierarchical linguistic structures do not have boundaries that are clearly defined by acoustic cues and must therefore be internally and incrementally constructed during comprehension. We found that, during listening to connected speech, cortical activity of different timescales concurrently tracked the time course of abstract linguistic structures at different hierarchical levels, such as words, phrases and sentences. Notably, the neural tracking of hierarchical linguistic structures was dissociated from the encoding of acoustic cues and from the predictability of incoming words. Our results indicate that a hierarchy of neural processing timescales underlies grammar-based internal construction of hierarchical linguistic structure.

  20. Mechanically robust superhydrophobicity on hierarchically structured Si surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Xiu Yonghao; Hess, Dennis W [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0100 (United States); Liu Yan; Wong, C P, E-mail: dennis.hess@chbe.gatech.edu, E-mail: cp.wong@mse.gatech.edu [School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive, Atlanta, GA 30332-0245 (United States)

    2010-04-16

    Improvement of the robustness of superhydrophobic surfaces is critical in order to achieve commercial applications of these surfaces in such diverse areas as self-cleaning, water repellency and corrosion resistance. In this study, the mechanical robustness of superhydrophobic surfaces was evaluated on hierarchically structured silicon surfaces. The effect of two-scale hierarchical structures on robustness was investigated using an abrasion test and the results compared to those of superhydrophobic surfaces fabricated from polymeric materials and from silicon that contains only nanostructures. Unlike the polymeric and nanostructure-only surfaces, the hierarchical structures retained superhydrophobic behavior after mechanical abrasion.

  1. Hierarchically Structured Monolithic ZSM-5 through Macroporous Silica Gel Zeolitization

    Institute of Scientific and Technical Information of China (English)

    Lei Qian; Zhao Tianbo; Li Fengyan; Zong Baoning; Tong Yangchuan

    2006-01-01

    The hierarchically structured ZSM-5 monolith was prepared through transforming the skeletons of the macroporous silica gel into ZSM-5 by the steam-assisted conversion method. The morphology and monolithic shapes of macroporous silica gel were well preserved. The hierarchically structured ZSM-5 monolith exhibited the hierarchical porosity, with mesopores and macropores existing inside the macroporous silica gel, and micropores formed by the ZSM-5. The products have been characterized properly by using the XRD, SEM and N2 adsorption-desorption methods.

  2. Hierarchical Optimization of Material and Structure

    DEFF Research Database (Denmark)

    Rodrigues, Helder C.; Guedes, Jose M.; Bendsøe, Martin P.

    2002-01-01

    This paper describes a hierarchical computational procedure for optimizing material distribution as well as the local material properties of mechanical elements. The local properties are designed using a topology design approach, leading to single scale microstructures, which may be restricted...... in various ways, based on design and manufacturing criteria. Implementation issues are also discussed and computational results illustrate the nature of the procedure....

  3. Hierarchical structure of moral stages assessed by a sorting task

    OpenAIRE

    Van Boom, J; Brugman, D.; Heijden, P.G.M. van der

    2001-01-01

    Following criticism of Kohlberg’s theory of moral judgment, an empirical re-examination of hierarchical stage structure was desirable. Utilizing Piaget’s concept of reflective abstraction as a basis, the hierarchical stage structure was investigated using a new method. Study participants (553 Dutch university students and 196 Russian high school students) sorted statements in terms of moral sophistication. These statements were typical for the different stages of moral development as defined ...

  4. Road Network Selection Based on Road Hierarchical Structure Control

    Directory of Open Access Journals (Sweden)

    HE Haiwei

    2015-04-01

    Full Text Available A new road network selection method based on hierarchical structure is studied. Firstly, road network is built as strokes which are then classified into hierarchical collections according to the criteria of betweenness centrality value (BC value. Secondly, the hierarchical structure of the strokes is enhanced using structural characteristic identification technique. Thirdly, the importance calculation model was established according to the relationships among the hierarchical structure of the strokes. Finally, the importance values of strokes are got supported with the model's hierarchical calculation, and with which the road network is selected. Tests are done to verify the advantage of this method by comparing it with other common stroke-oriented methods using three kinds of typical road network data. Comparision of the results show that this method had few need to semantic data, and could eliminate the negative influence of edge strokes caused by the criteria of BC value well. So, it is better to maintain the global hierarchical structure of road network, and suitable to meet with the selection of various kinds of road network at the same time.

  5. 3D Printing of Hierarchical Silk Fibroin Structures.

    Science.gov (United States)

    Sommer, Marianne R; Schaffner, Manuel; Carnelli, Davide; Studart, André R

    2016-12-21

    Like many other natural materials, silk is hierarchically structured from the amino acid level up to the cocoon or spider web macroscopic structures. Despite being used industrially in a number of applications, hierarchically structured silk fibroin objects with a similar degree of architectural control as in natural structures have not been produced yet due to limitations in fabrication processes. In a combined top-down and bottom-up approach, we exploit the freedom in macroscopic design offered by 3D printing and the template-guided assembly of ink building blocks at the meso- and nanolevel to fabricate hierarchical silk porous materials with unprecedented structural control. Pores with tunable sizes in the range 40-350 μm are generated by adding sacrificial organic microparticles as templates to a silk fibroin-based ink. Commercially available wax particles or monodisperse polycaprolactone made by microfluidics can be used as microparticle templates. Since closed pores are generated after template removal, an ultrasonication treatment can optionally be used to achieve open porosity. Such pore templating particles can be further modified with nanoparticles to create a hierarchical template that results in porous structures with a defined nanotopography on the pore walls. The hierarchically porous silk structures obtained with this processing technique can potentially be utilized in various application fields from structural materials to thermal insulation to tissue engineering scaffolds.

  6. Examining the Factor Structure and Hierarchical Nature of the Quality of Life Construct

    Science.gov (United States)

    Wang, Mian; Schalock, Robert L.; Verdugo, Miguel A.; Jenaro, Christina

    2010-01-01

    There is considerable debate in the area of individual quality of life research regarding the factor structure and hierarchical nature of the quality of life construct. Our purpose in this study was to test via structural equation modeling an a priori quality of life model consisting of eight first-order factors and one second-order factor. Data…

  7. Detect overlapping and hierarchical community structure in networks

    CERN Document Server

    Shen, Huawei; Cai, Kai; Hu, Mao-Bin

    2008-01-01

    Clustering and community structure is crucial for many network systems and the related dynamic processes. It has been shown that communities are usually overlapping and hierarchical. However, previous methods investigate these two properties of community structure separately. This paper propose an algorithm (EAGLE) to detect both the overlapping and hierarchical properties of complex community structure together. This algorithm deals with the set of maximal cliques and adopts an agglomerative framework. The quality function of modularity is extended to evaluate the goodness of a cover. The examples of application to real world networks give excellent results.

  8. Trait anxiety, disgust sensitivity, and the hierarchic structure of fears.

    Science.gov (United States)

    McDonald, Scott D; Hartman, Nathan S; Vrana, Scott R

    2008-08-01

    This paper describes an evaluation of Taylor's (1998) hierarchic model of fears and its relationship to trait anxiety and disgust sensitivity (DS). In Study 1 (N=420), a confirmatory factor analysis supported a hierarchic structure of fears. Next, an analysis using structural equation modeling indicated that trait anxiety is associated with claustrophobic and social fears, whereas DS is associated with all four fear subtypes examined (claustrophobic, social, blood-injection-injury and animal). However, trait anxiety and DS did not account for all variance shared by fear subtypes. The addition of a generalized "fear factor" accounted for significant residual shared variance between the four fear subtypes, beyond that accounted for by trait anxiety and DS. Study 2 (N=213) generally replicated these results. Findings suggest that the hierarchic structural model of fears would benefit from inclusion of trait anxiety and DS as higher-order contributors to fearfulness.

  9. Structure of urban movements: polycentric activity and entangled hierarchical flows.

    Directory of Open Access Journals (Sweden)

    Camille Roth

    Full Text Available The spatial arrangement of urban hubs and centers and how individuals interact with these centers is a crucial problem with many applications ranging from urban planning to epidemiology. We utilize here in an unprecedented manner the large scale, real-time 'Oyster' card database of individual person movements in the London subway to reveal the structure and organization of the city. We show that patterns of intraurban movement are strongly heterogeneous in terms of volume, but not in terms of distance travelled, and that there is a polycentric structure composed of large flows organized around a limited number of activity centers. For smaller flows, the pattern of connections becomes richer and more complex and is not strictly hierarchical since it mixes different levels consisting of different orders of magnitude. This new understanding can shed light on the impact of new urban projects on the evolution of the polycentric configuration of a city and the dense structure of its centers and it provides an initial approach to modeling flows in an urban system.

  10. Micro-nanofibers with hierarchical structure by bubbfil-spinning

    Directory of Open Access Journals (Sweden)

    Liu Peng

    2015-01-01

    Full Text Available Bubbfil spinning is used to fabricate micro/nanofibers with hierarchical structure. The wall of a polymer film is attenuated unevenly by a blowing air. The burst of the bubble results in film fragments with different thickness, as a result, different sizes of fibers are obtained.

  11. Hierarchically structured superoleophobic surfaces with ultralow contact angle hysteresis.

    Science.gov (United States)

    Kota, Arun K; Li, Yongxin; Mabry, Joseph M; Tuteja, Anish

    2012-11-14

    Hierarchically structured, superoleophobic surfaces are demonstrated that display one of the lowest contact angle hysteresis values ever reported - even with extremely low-surface-tension liquids such as n-heptane. Consequently, these surfaces allow, for the first time, even ≈2 μL n-heptane droplets to bounce and roll-off at tilt angles. ≤ 2°.

  12. Content Consumption and Hierarchical Structures of Web-Supported Courses

    Science.gov (United States)

    Hershkovitz, Arnon; Hardof-Jaffe, Sharon; Nachmias, Rafi

    2014-01-01

    This study presents an empirical investigation of the relationship between the hierarchical structure of content delivered to students within a Learning Management System (LMS) and its actual consumption. To this end, campus-wide data relating to 1,203 courses were collected from the LMS' servers and were subsequently analyzed using data mining…

  13. Hierarchical structures of ZnO spherical particles synthesized solvothermally

    Science.gov (United States)

    Saito, Noriko; Haneda, Hajime

    2011-12-01

    We review the solvothermal synthesis, using a mixture of ethylene glycol (EG) and water as the solvent, of zinc oxide (ZnO) particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i) EG restricts the growth of ZnO microcrystals, (ii) EG promotes the self-assembly of small crystallites into spheroidal particles and (iii) the high water content of EG results in hollow spheres.

  14. Hierarchical structures of ZnO spherical particles synthesized solvothermally

    Directory of Open Access Journals (Sweden)

    Noriko Saito and Hajime Haneda

    2011-01-01

    Full Text Available We review the solvothermal synthesis, using a mixture of ethylene glycol (EG and water as the solvent, of zinc oxide (ZnO particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i EG restricts the growth of ZnO microcrystals, (ii EG promotes the self-assembly of small crystallites into spheroidal particles and (iii the high water content of EG results in hollow spheres.

  15. Evaluating Hierarchical Structure in Music Annotations

    OpenAIRE

    Brian McFee; Oriol Nieto; Morwaread M. Farbood; Juan Pablo Bello

    2017-01-01

    Music exhibits structure at multiple scales, ranging from motifs to large-scale functional components. When inferring the structure of a piece, different listeners may attend to different temporal scales, which can result in disagreements when they describe the same piece. In the field of music informatics research (MIR), it is common to use corpora annotated with structural boundaries at different levels. By quantifying disagreements between multiple annotators, previous research has yielded...

  16. Hierarchical Self-Assembled Structures from POSS-Containing Block Copolymers Synthesized by Living Anionic Polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, Tomoyasu; Leolukman, Melvina; Jin, Sangwoo; Goseki, Raita; Ishida, Yoshihito; Kakimoto, Masa-aki; Hayakawa, Teruaki; Ree, Moonhor; Gopalan, Padma; (Tokyo Inst. Tech.); (UW); (POSTECH)

    2010-03-16

    Two kinds of polyhedral oligomeric silsesquioxane (POSS)-containing block copolymers (BCPs), namely PS-b-PMAPOSS and PMMA-b-PMAPOSS, were synthesized by living anionic polymerization. A wide range of molecular weights were obtained with a very narrow polydispersity index of less than 1.09. The bulk samples prepared by slow evaporation from a polymer solution in chloroform exhibit well-defined microphase-separated structures with long-range order. Thermal annealing induced hierarchical structures consisting of a smaller length scale ordered crystalline POSS domains within the larger microphase-separated structures. We report detailed structural characterization of these hierarchical structures in bulk and thin films by transmission electron microscopy and grazing incidence wide-angle X-ray scattering (GIWAXS). On the basis of this structural analysis, we propose a model for the formation of an orthorhombic lattice structure through the aggregation of POSS segments which formed a helix-like structure.

  17. Auction-based resource allocation game under a hierarchical structure

    Science.gov (United States)

    Cui, Yingying; Zou, Suli; Ma, Zhongjing

    2016-01-01

    This paper studies a class of auction-based resource allocation games under a hierarchical structure, such that each supplier is assigned a certain amount of resource from a single provider and allocates it to its buyers with auction mechanisms. To implement the efficient allocations for the underlying hierarchical system, we first design an auction mechanism, for each local system composed of a supplier and its buyers, which inherits the advantages of the progressive second price mechanism. By employing a dynamic algorithm, each local system converges to its own efficient Nash equilibrium, at which the efficient resource allocation is achieved and the bidding prices of all the buyers in this local system are identical with each other. After the local systems reach their own equilibria respectively, the resources assigned to suppliers are readjusted via a dynamic hierarchical algorithm with respect to the bidding prices associated with the implemented equilibria of local systems. By applying the proposed hierarchical process, the formulated hierarchical system can converge to the efficient allocation under certain mild conditions. The developed results in this work are demonstrated with simulations.

  18. Hierarchical expansion of the kinetic energy operator in curvilinear coordinates for the vibrational self-consistent field method.

    Science.gov (United States)

    Strobusch, D; Scheurer, Ch

    2011-09-28

    A new hierarchical expansion of the kinetic energy operator in curvilinear coordinates is presented and modified vibrational self-consistent field (VSCF) equations are derived including all kinematic effects within the mean field approximation. The new concept for the kinetic energy operator is based on many-body expansions for all G matrix elements and its determinant. As a test application VSCF computations were performed on the H(2)O(2) molecule using an analytic potential (PCPSDE) and different hierarchical approximations for the kinetic energy operator. The results indicate that coordinate-dependent reduced masses account for the largest part of the kinetic energy. Neither kinematic couplings nor derivatives of the G matrix nor its determinant had significant effects on the VSCF energies. Only the zero-point value of the pseudopotential yields an offset to absolute energies which, however, is irrelevant for spectroscopic problems.

  19. Zeólitas hierarquicamente estruturadas Hierarchically structured zeolites

    Directory of Open Access Journals (Sweden)

    Saulo de Tarso Figueiredo Grecco

    2013-01-01

    Full Text Available This review presents the main characteristics and properties of microporous (zeolites and ordered mesoporous materials, focusing on structural aspects and preparation. In addition, their use as heterogeneous catalysts are also discussed, with emphasis on their advantages and disadvantages. Due to difficulty in application of zeolites in the conversion of bulky molecules, the most relevant strategies of synthesis for the preparation of zeolitic materials with hierarchical pore structure was also analyzed, which allow this limitation to be overcome.

  20. Reliability and Hierarchical Structure of DSM-5 Pathological Traits in a Danish Mixed Sample

    DEFF Research Database (Denmark)

    Bo, Sune; Bach, Bo; Mortensen, Erik Lykke

    2016-01-01

    In this study we assessed the DSM-5 trait model in a large Danish sample (n = 1,119) with respect to reliability of the applied Danish version of the Personality Inventory for DSM-5 (PID-5) self-report form by means of internal consistency and item discrimination. In addition, we tested whether...... the five-factor structure of the DSM-5 trait model can be replicated in a Danish independent sample using the PID-5 self-report form. Finally, we examined the hierarchical structure of DSM-5 traits. In terms of internal consistency and item discrimination, the applied PID-5 scales were generally found...... reliable and functional; our data resembled the five-factor structure of previous findings, and we identified a hierarchical structure from one to five factors that was conceptually reasonable and corresponded with existing findings. These results support the new DSM-5 trait model and suggest that it can...

  1. PATH PRIORITIZATION AND OPERATIONAL CONSISTENCY FOR DYNAMIC TRAFFIC ASSIGNMENT: AN ANALYTIC HIERARCHICAL APPROACH

    Directory of Open Access Journals (Sweden)

    Srinivas Bulusu

    2016-06-01

    Full Text Available An operational consistency model for real-time dynamic traffic assignment (DTA applications seeks to correct the time-dependent path assignment within a rolling horizon scheme. This study extends an existing consistency framework to develop a hierarchy for the time-dependent path set based upon their relative importance to ensuring consistency. Using the analytic hierarchy process, the eigenvalue associated with a path is identified as the parameter which enables the rank ordering of paths. The ability to identify a subset of dominant paths relative to enhancing consistency enhances the computational viability of the consistency framework for real-time implementation and has significant practical implications. Additionally, it provides insights on the complex dynamics that are inherent to the operational consistency problem.

  2. Hierarchical semantic structures for medical NLP.

    Science.gov (United States)

    Taira, Ricky K; Arnold, Corey W

    2013-01-01

    We present a framework for building a medical natural language processing (NLP) system capable of deep understanding of clinical text reports. The framework helps developers understand how various NLP-related efforts and knowledge sources can be integrated. The aspects considered include: 1) computational issues dealing with defining layers of intermediate semantic structures to reduce the dimensionality of the NLP problem; 2) algorithmic issues in which we survey the NLP literature and discuss state-of-the-art procedures used to map between various levels of the hierarchy; and 3) implementation issues to software developers with available resources. The objective of this poster is to educate readers to the various levels of semantic representation (e.g., word level concepts, ontological concepts, logical relations, logical frames, discourse structures, etc.). The poster presents an architecture for which diverse efforts and resources in medical NLP can be integrated in a principled way.

  3. Information and hierarchical structure in financial markets

    Science.gov (United States)

    Mantegna, R. N.

    1999-09-01

    I investigate the information content present in the time series of stock prices of a portfolio of stocks traded in a financial market. By investigating the correlation coefficient between pairs of stocks I provide a working definition of a generalized distance between the stocks of the portfolio. This generalized distance is used to obtain an ultrametric distance matrix between the stocks. The ultrametric structure of the portfolio investigated has associated a taxonomy which is meaningful from an economic point of view.

  4. The Hierarchical Structure and Dynamics of Voids

    CERN Document Server

    Aragon-Calvo, M A

    2012-01-01

    Contrary to the common view voids have very complex internal structure and dynamics. Here we show how the hierarchy of structures in the density field inside voids is reflected by a similar hierarchy of structures in the velocity field. Voids defined by dense filaments and clusters can de described as simple expanding domains with coherent flows everywhere except at their boundaries. At scales smaller that the void radius the velocity field breaks into expanding sub-domains corresponding to sub- voids. These sub-domains break into even smaller sub-sub domains at smaller scales resulting in a nesting hierarchy of locally expanding domains. The ratio between the magnitude of the velocity field responsible for the expansion of the void and the velocity field defining the sub voids is approximately one order of magnitude. The small-scale components of the velocity field play a minor role in the shaping of the voids but they define the local dynamics directly affecting the processes of galaxy formation and evoluti...

  5. Growth Mechanism of Pumpkin-Shaped Vaterite Hierarchical Structures

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2015-03-01

    CaCO3-based biominerals possess sophisticated hierarchical structures and promising mechanical properties. Recent researches imply that vaterite may play an important role in formation of CaCO3-based biominerals. However, as a less common polymorph of CaCO3, the growth mechanism of vaterite remains not very clear. Here we report the growth of a pumpkin-shaped vaterite hierarchical structure with a six-fold symmetrical axis and lamellar microstructure. We demonstrate that the growth is controlled by supersaturation and the intrinsic crystallographic anisotropy of vaterite. For the scenario of high supersaturation, the nucleation rate is higher than the lateral extension rate, favoring the ``double-leaf'' spherulitic growth. Meanwhile, nucleation occurs preferentially in as determined by the crystalline structure of vaterite, modulating the grown products with a hexagonal symmetry. The results are beneficial for an in-depth understanding of the biomineralization of CaCO3. The growth mechanism may also be applicable to interpret the formation of similar hierarchical structures of other materials. The authors gratefully acknowledge the financial support from National Science Foundation of China (Grant Nos. 51172104 and 50972057) and National Key Basic Research Program of China (Grant No. 2010CB630705).

  6. Simulating Self-organization and Interference between Certain Hierarchical Structures.

    Science.gov (United States)

    Raczynski, Stanislaw

    2014-10-01

    A model of the dynamics and interactions between organizations with self-organizing hierarchical structures is presented for discrete events. The active objects of the model are individuals (people, organization members). The parameters of an individual are ability, corruption level, resources, and lust for power, among others. Three organizations are generated and interact with each other, attempting to gain more members and power. The individuals appear and disappear, due to a simple 'birth-and-death' process. If an individual disappears from the model, a corresponding reconfiguration in the hierarchical structure occurs. The organization's growth and macro-patterns are the result of the activities of the individuals. The aim of the simulation is to visualize the evolution of the organizations and the stability of the whole system. A 'steady state' for the model is rare; instead, in most parameter configurations, the model enters into oscillations.

  7. Hierarchical Cellular Structures in High-Capacity Cellular Communication Systems

    CERN Document Server

    Jain, R K; Agrawal, N K

    2011-01-01

    In the prevailing cellular environment, it is important to provide the resources for the fluctuating traffic demand exactly in the place and at the time where and when they are needed. In this paper, we explored the ability of hierarchical cellular structures with inter layer reuse to increase the capacity of mobile communication network by applying total frequency hopping (T-FH) and adaptive frequency allocation (AFA) as a strategy to reuse the macro and micro cell resources without frequency planning in indoor pico cells [11]. The practical aspects for designing macro- micro cellular overlays in the existing big urban areas are also explained [4]. Femto cells are inducted in macro / micro / pico cells hierarchical structure to achieve the required QoS cost effectively.

  8. D Nearest Neighbour Search Using a Clustered Hierarchical Tree Structure

    Science.gov (United States)

    Suhaibah, A.; Uznir, U.; Anton, F.; Mioc, D.; Rahman, A. A.

    2016-06-01

    Locating and analysing the location of new stores or outlets is one of the common issues facing retailers and franchisers. This is due to assure that new opening stores are at their strategic location to attract the highest possible number of customers. Spatial information is used to manage, maintain and analyse these store locations. However, since the business of franchising and chain stores in urban areas runs within high rise multi-level buildings, a three-dimensional (3D) method is prominently required in order to locate and identify the surrounding information such as at which level of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN) analysis. It uses a point location and identifies the surrounding neighbours. However, with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results are presented in this paper. Another advantage of this structure is that it also offers a minimal overlap and coverage among nodes which can reduce repetitive data entry.

  9. Hierarchical structure of biological systems: A bioengineering approach

    OpenAIRE

    Alcocer-Cuarón, Carlos; Rivera, Ana L; Castaño, Victor M.

    2013-01-01

    A general theory of biological systems, based on few fundamental propositions, allows a generalization of both Wierner and Berthalanffy approaches to theoretical biology. Here, a biological system is defined as a set of self-organized, differentiated elements that interact pair-wise through various networks and media, isolated from other sets by boundaries. Their relation to other systems can be described as a closed loop in a steady-state, which leads to a hierarchical structure and function...

  10. Concept Vector for Similarity Measurement Based on Hierarchical Domain Structure

    OpenAIRE

    Hong Zhe Liu; Hong Bao; Xu

    2012-01-01

    The concept vector model generalizes standard representations of similarity concept in terms of tree-like structure. In the model, each concept node in the hierarchical tree has ancestor and descendent concept nodes composing its relevancy nodes, thus a concept node is represented as a concept vector according to its relevancy nodes' density and the similarity of the two concepts is obtained by computing cosine similarity between their vectors. In addition, the model is adjusted in terms of l...

  11. Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

    Institute of Scientific and Technical Information of China (English)

    Weiyan Meng; Yanmin Zhou; Yanjing Zhang; Qing Cai; Liming Yang; Jinghui Zhao; Chnnyan Li

    2011-01-01

    In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hierarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching (EE). MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched (SLA) as well as Machined (M) surfaces respectively. The results show significant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

  12. Hierarchical structure of moral stages assessed by a sorting task.

    Science.gov (United States)

    Boom, J; Brugman, D; van der Heijden, P G

    2001-01-01

    Following criticism of Kohlberg's theory of moral judgment, an empirical re-examination of hierarchical stage structure was desirable. Utilizing Piaget's concept of reflective abstraction as a basis, the hierarchical stage structure was investigated using a new method. Study participants (553 Dutch university students and 196 Russian high school students) sorted statements in terms of moral sophistication. These statements were typical for the different stages of moral development as defined in Colby and Kohlberg. The rank ordering performed by participants confirmed the hypotheses. First, despite large individual variation, the ordering of the statements that gave the best fit revealed that each consecutive Kohlbergian stage was perceived to be more morally sophisticated. Second, the lower the stage as represented by the items, the higher the agreement among the participants in their ranking; and the higher the stage as represented by the items, the lower the agreement among the participants in the rankings. Moreover, the pivotal point depended on the developmental characteristics of the sample, which demonstrated a developmental effect: The ordering of statements representative of moral stages below one's own current stage was straightforward, whereas the ordering of statements above one's own stage was difficult. It was concluded that the Piagetian idea of reflective abstraction can be used successfully to operationalize and measure the hierarchical nature of moral development.

  13. Study on Hierarchical Structure of Detailed Control Planning

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Using case studies,this paper analyzes the characteristics of detailed control planning and its hierarchical controls,the form and composition of plan content,and methodological innovations.It then suggests improvements to the planning structure that are oriented at adaptability,fairness,centrality,and scientific principles with regard to the content,methods,and results of the planning.Regarding the hierarchical control system,the paper suggests that the detailed control plan should be composed of "block planning" and "plot planning".It is believed that through a combination of block and plot planning,the problem of joining long-term and short-term planning will be solved and it will be possible to address the need for adjustment and revision of detailed control plan.

  14. An interference cancellation strategy for broadcast in hierarchical cell structure

    KAUST Repository

    Yang, Yuli

    2014-12-01

    In this paper, a hierarchical cell structure is considered, where public safety broadcasting is fulfilled in a femtocell located within a macrocell. In the femtocell, also known as local cell, an access point broadcasts to each local node (LN) over an orthogonal frequency sub-band independently. Since the local cell shares the spectrum licensed to the macrocell, a given LN is interfered by transmissions of the macrocell user (MU) in the same sub-band. To improve the broadcast performance in the local cell, a novel scheme is proposed to mitigate the interference from the MU to the LN while achieving diversity gain. For the sake of performance evaluation, ergodic capacity of the proposed scheme is quantified and a corresponding closed-form expression is obtained. By comparing with the traditional scheme that suffers from the MU\\'s interference, numerical results substantiate the advantage of the proposed scheme and provide a useful tool for the broadcast design in hierarchical cell systems.

  15. Synthesis of nickel hierarchical structures and evaluation on their magnetic properties and Congo red removal ability.

    Science.gov (United States)

    Zhang, Guangshu; Zhao, Lijun

    2013-03-14

    Novel nickel hierarchical structures were prepared through a facile one-pot solvothermal approach in the presence of surfactant and mineralizer. The influence of dynamics factors such as polyvinylpyrrolidone (PVP) content, ratio (R) between NaF and NH(3)·H(2)O on the morphologies of the as-synthesized products were investigated in detail. By regulating the dynamics factors, nickel crystals with three different structures (hcp and fcc mixture structure, fcc structure and a mostly hcp structure) were synthesized. Meanwhile, the corresponding morphologies are changed from hierarchical structures composed of nanoparticles to hierarchical structures consisted of nanoflakes, and to polyhedra. The values of saturation magnetizations of nickel crystals also range from 41.6 to 8 emu g(-1) because of the change of crystal structure from fcc to mostly hcp. One thing to be mentioned is that the mostly hcp phase can be completely converted into fcc phase if the solvothermal treatment temperature is further enhanced to 220 °C. Further, the Congo red (CR) removal ability by the as-obtained nickel particles was evaluated. By the investigation of adsorption and desorption experiments on nickel powders, we can ascertain that chemical reduction and physical adsorption happen at the same time during the treatment process of CR solution.

  16. Nanodomain structures with hierarchical inhomogeneities in PMN-PT.

    Science.gov (United States)

    Kurushima, Kosuke; Kobayashi, Keisuke; Mori, Shigeo

    2012-09-01

    The nanometric domain configuration of (1 - x) Pb(Mg(1/3)Nb(2/3))O(3-x)PbTiO(3) [(1 - x)PMN-xPT] single crystals in the monoclinic phase around a morphotropic phase boundary (MPB) has been examined thoroughly by means of transmission electron microscopy (TEM). Domain structures with hierarchically inhomogeneous configuration were found in the monoclinic phase near the MPB region around x ~ 0.32, which are characterized as nanoscaled lamella-type domain structures with ~10 nm width inside macroscopic-sized banded domains with 100 to 200 nm width. To elucidate formation processes of the domain structures with hierarchically inhomogeneous configuration, an in situ TEM observation of changes of the domain structures in the temperature window between 298K and 500K was carried out. It is revealed that these nanoscaled lamella-type domain structures with ~10 nm width appear inside the banded domains as a result of the tetragonal structure and are inherent to the monoclinic phase.

  17. Gene function prediction based on the Gene Ontology hierarchical structure.

    Science.gov (United States)

    Cheng, Liangxi; Lin, Hongfei; Hu, Yuncui; Wang, Jian; Yang, Zhihao

    2014-01-01

    The information of the Gene Ontology annotation is helpful in the explanation of life science phenomena, and can provide great support for the research of the biomedical field. The use of the Gene Ontology is gradually affecting the way people store and understand bioinformatic data. To facilitate the prediction of gene functions with the aid of text mining methods and existing resources, we transform it into a multi-label top-down classification problem and develop a method that uses the hierarchical relationships in the Gene Ontology structure to relieve the quantitative imbalance of positive and negative training samples. Meanwhile the method enhances the discriminating ability of classifiers by retaining and highlighting the key training samples. Additionally, the top-down classifier based on a tree structure takes the relationship of target classes into consideration and thus solves the incompatibility between the classification results and the Gene Ontology structure. Our experiment on the Gene Ontology annotation corpus achieves an F-value performance of 50.7% (precision: 52.7% recall: 48.9%). The experimental results demonstrate that when the size of training set is small, it can be expanded via topological propagation of associated documents between the parent and child nodes in the tree structure. The top-down classification model applies to the set of texts in an ontology structure or with a hierarchical relationship.

  18. Hierarchical surface atomic structure of a manganese-based spinel cathode for lithium-ion batteries.

    Science.gov (United States)

    Lee, Sanghan; Yoon, Gabin; Jeong, Minseul; Lee, Min-Joon; Kang, Kisuk; Cho, Jaephil

    2015-01-19

    The increasing use of lithium-ion batteries (LIBs) in high-power applications requires improvement of their high-temperature electrochemical performance, including their cyclability and rate capability. Spinel lithium manganese oxide (LiMn2O4) is a promising cathode material because of its high stability and abundance. However, it exhibits poor cycling performance at high temperatures owing to Mn dissolution. Herein we show that when stoichiometric lithium manganese oxide is coated with highly doped spinels, the resulting epitaxial coating has a hierarchical atomic structure consisting of cubic-spinel, tetragonal-spinel, and layered structures, and no interfacial phase is formed. In a practical application of the coating to doped spinel, the material retained 90% of its capacity after 800 cycles at 60 °C. Thus, the formation of an epitaxial coating with a hierarchical atomic structure could enhance the electrochemical performance of LIB cathode materials while preventing large losses in capacity.

  19. A stochastic model for detecting overlapping and hierarchical community structure.

    Directory of Open Access Journals (Sweden)

    Xiaochun Cao

    Full Text Available Community detection is a fundamental problem in the analysis of complex networks. Recently, many researchers have concentrated on the detection of overlapping communities, where a vertex may belong to more than one community. However, most current methods require the number (or the size of the communities as a priori information, which is usually unavailable in real-world networks. Thus, a practical algorithm should not only find the overlapping community structure, but also automatically determine the number of communities. Furthermore, it is preferable if this method is able to reveal the hierarchical structure of networks as well. In this work, we firstly propose a generative model that employs a nonnegative matrix factorization (NMF formulization with a l(2,1 norm regularization term, balanced by a resolution parameter. The NMF has the nature that provides overlapping community structure by assigning soft membership variables to each vertex; the l(2,1 regularization term is a technique of group sparsity which can automatically determine the number of communities by penalizing too many nonempty communities; and hence the resolution parameter enables us to explore the hierarchical structure of networks. Thereafter, we derive the multiplicative update rule to learn the model parameters, and offer the proof of its correctness. Finally, we test our approach on a variety of synthetic and real-world networks, and compare it with some state-of-the-art algorithms. The results validate the superior performance of our new method.

  20. Hierarchical structure of the otolith of adult wild carp

    Energy Technology Data Exchange (ETDEWEB)

    Li Zhuo; Gao Yonghua [State key laboratory of new ceramics and fine processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Feng Qingling, E-mail: biomater@mail.tsinghua.edu.cn [State key laboratory of new ceramics and fine processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2009-04-30

    The otolith of adult wild carp contains a pair of asterisci, a pair of lappilli and a pair of sagittae. Current research works are mainly restricted to the field of the daily ring structure. The purpose of this work is to explore the structural characteristics of carp's otolith in terms of hierarchy from nanometer to millimeter scale by transmission election microscope (TEM) and scanning electron microscope (SEM). Based on the observation, carp's lapillus is composed of ordered aragonite crystals. Seven hierarchical levels of the microstructure were proposed and described with the scheme representing a complete organization in detail. SEM studies show not only the clear daily growth increment, but also the morphology within the single daily increment. The domain structure of crystal orientation in otolith was observed for the first time. Furthermore, TEM investigation displays that the lapillus is composed of aragonite crystals with nanometer scale. Four hierarchical levels of the microstructure of the sagitta are also proposed. The asteriscus which is composed of nanometer scale vaterite crystals is considered to have a uniform structure.

  1. Hierarchical optimisation on scissor seat suspension characteristic and structure

    Science.gov (United States)

    Wang, Chunlei; Zhang, Xinjie; Guo, Konghui; Lv, Jiming; Yang, Yi

    2016-11-01

    Scissor seat suspension has been applied widely to attenuate the cab vibrations of commercial vehicles, while its design generally needs a trade-off between the seat acceleration and suspension travel, which creates a typical optimisation issue. A complexity for this issue is that the optimal dynamics parameters are not easy to approach solutions fast and unequivocally. Hence, the hierarchical optimisation on scissor seat suspension characteristic and structure is proposed, providing a top-down methodology with the globally optimal and fast convergent solutions to compromise these design contradictions. In details, a characteristic-oriented non-parametric dynamics model of the scissor seat suspension is formulated firstly via databases, describing its vertical dynamics accurately. Then, the ideal vertical stiffness-damping characteristic is cascaded via the characteristic-oriented model, and the structure parameters are optimised in accordance with a structure-oriented multi-body dynamics model of the scissor seat suspension. Eventually, the seat effective amplitude transmissibility factor, suspension travel and the CPU time for solving are evaluated. The results show the seat suspension performance and convergent speed of the globally optimal solutions are improved well. Hence, the proposed hierarchical optimisation methodology regarding characteristic and structure of the scissor seat suspension is promising for its virtual development.

  2. Connectivity independent protein-structure alignment: a hierarchical approach

    Directory of Open Access Journals (Sweden)

    Schmidt-Goenner Tobias

    2006-11-01

    Full Text Available Abstract Background Protein-structure alignment is a fundamental tool to study protein function, evolution and model building. In the last decade several methods for structure alignment were introduced, but most of them ignore that structurally similar proteins can share the same spatial arrangement of secondary structure elements (SSE but differ in the underlying polypeptide chain connectivity (non-sequential SSE connectivity. Results We perform protein-structure alignment using a two-level hierarchical approach implemented in the program GANGSTA. On the first level, pair contacts and relative orientations between SSEs (i.e. α-helices and β-strands are maximized with a genetic algorithm (GA. On the second level residue pair contacts from the best SSE alignments are optimized. We have tested the method on visually optimized structure alignments of protein pairs (pairwise mode and for database scans. For a given protein structure, our method is able to detect significant structural similarity of functionally important folds with non-sequential SSE connectivity. The performance for structure alignments with strictly sequential SSE connectivity is comparable to that of other structure alignment methods. Conclusion As demonstrated for several applications, GANGSTA finds meaningful protein-structure alignments independent of the SSE connectivity. GANGSTA is able to detect structural similarity of protein folds that are assigned to different superfamilies but nevertheless possess similar structures and perform related functions, even if these proteins differ in SSE connectivity.

  3. Numerical analysis on mechanical behaviors of hierarchical cellular structures with negative Poisson’s ratio

    Science.gov (United States)

    Li, Dong; Yin, Jianhua; Dong, Liang; Lakes, Roderic S.

    2017-02-01

    Two-dimensional hierarchical re-entrant honeycomb structures were designed and the mechanical behaviors of the structures were studied using a finite element method. Hierarchical re-entrant structure of order n (n ≥ 1) was constructed by replacing each vertex of a lower order (n - 1) hierarchical re-entrant structure with a smaller re-entrant hexagon with identical strut aspect ratio. The Poisson’s ratio and energy absorption capacity of re-entrant structures of different hierarchical orders were studied under different compression velocities. The results showed that the Poisson’s ratio of the first and second order hierarchical structures can reach -1.36 and -1.33 with appropriate aspect ratio, 13.8% and 12.1% lower than that of the zeroth order hierarchical structure. The energy absorption capacity of the three models increased with an increasing compression velocity; the second order hierarchical structure exhibited the highest rate of increase in energy absorption capacity with an increasing compression velocity. The plateau stresses of the first and second order hierarchical structures were slightly lower than that of the zeroth order hierarchical structure; however the second order hierarchical structure exhibited the highest energy absorption capacity at high compression velocity (60 m s-1).

  4. Analysis of stability of community structure across multiple hierarchical levels

    CERN Document Server

    Li, Hui-Jia

    2015-01-01

    The analysis of stability of community structure is an important problem for scientists from many fields. Here, we propose a new framework to reveal hidden properties of community structure by quantitatively analyzing the dynamics of Potts model. Specifically we model the Potts procedure of community structure detection by a Markov process, which has a clear mathematical explanation. Critical topological information regarding to multivariate spin configuration could also be inferred from the spectral significance of the Markov process. We test our framework on some example networks and find it doesn't have resolute limitation problem at all. Results have shown the model we proposed is able to uncover hierarchical structure in different scales effectively and efficiently.

  5. A mechanism for the cortical computation of hierarchical linguistic structure.

    Science.gov (United States)

    Martin, Andrea E; Doumas, Leonidas A A

    2017-03-01

    Biological systems often detect species-specific signals in the environment. In humans, speech and language are species-specific signals of fundamental biological importance. To detect the linguistic signal, human brains must form hierarchical representations from a sequence of perceptual inputs distributed in time. What mechanism underlies this ability? One hypothesis is that the brain repurposed an available neurobiological mechanism when hierarchical linguistic representation became an efficient solution to a computational problem posed to the organism. Under such an account, a single mechanism must have the capacity to perform multiple, functionally related computations, e.g., detect the linguistic signal and perform other cognitive functions, while, ideally, oscillating like the human brain. We show that a computational model of analogy, built for an entirely different purpose-learning relational reasoning-processes sentences, represents their meaning, and, crucially, exhibits oscillatory activation patterns resembling cortical signals elicited by the same stimuli. Such redundancy in the cortical and machine signals is indicative of formal and mechanistic alignment between representational structure building and "cortical" oscillations. By inductive inference, this synergy suggests that the cortical signal reflects structure generation, just as the machine signal does. A single mechanism-using time to encode information across a layered network-generates the kind of (de)compositional representational hierarchy that is crucial for human language and offers a mechanistic linking hypothesis between linguistic representation and cortical computation.

  6. Colloidal quantum dot solar cells exploiting hierarchical structuring

    KAUST Repository

    Labelle, André J.

    2015-02-11

    Extremely thin-absorber solar cells offer low materials utilization and simplified manufacture but require improved means to enhance photon absorption in the active layer. Here, we report enhanced-absorption colloidal quantum dot (CQD) solar cells that feature transfer-stamped solution-processed pyramid-shaped electrodes employed in a hierarchically structured device. The pyramids increase, by up to a factor of 2, the external quantum efficiency of the device at absorption-limited wavelengths near the absorber band edge. We show that absorption enhancement can be optimized with increased pyramid angle with an appreciable net improvement in power conversion efficiency, that is, with the gain in current associated with improved absorption and extraction overcoming the smaller fractional decrease in open-circuit voltage associated with increased junction area. We show that the hierarchical combination of micron-scale structured electrodes with nanoscale films provides for an optimized enhancement at absorption-limited wavelengths. We fabricate 54.7° pyramid-patterned electrodes, conformally apply the quantum dot films, and report pyramid CQD solar cells that exhibit a 24% improvement in overall short-circuit current density with champion devices providing a power conversion efficiency of 9.2%.

  7. A mechanism for the cortical computation of hierarchical linguistic structure

    Science.gov (United States)

    Doumas, Leonidas A. A.

    2017-01-01

    Biological systems often detect species-specific signals in the environment. In humans, speech and language are species-specific signals of fundamental biological importance. To detect the linguistic signal, human brains must form hierarchical representations from a sequence of perceptual inputs distributed in time. What mechanism underlies this ability? One hypothesis is that the brain repurposed an available neurobiological mechanism when hierarchical linguistic representation became an efficient solution to a computational problem posed to the organism. Under such an account, a single mechanism must have the capacity to perform multiple, functionally related computations, e.g., detect the linguistic signal and perform other cognitive functions, while, ideally, oscillating like the human brain. We show that a computational model of analogy, built for an entirely different purpose—learning relational reasoning—processes sentences, represents their meaning, and, crucially, exhibits oscillatory activation patterns resembling cortical signals elicited by the same stimuli. Such redundancy in the cortical and machine signals is indicative of formal and mechanistic alignment between representational structure building and “cortical” oscillations. By inductive inference, this synergy suggests that the cortical signal reflects structure generation, just as the machine signal does. A single mechanism—using time to encode information across a layered network—generates the kind of (de)compositional representational hierarchy that is crucial for human language and offers a mechanistic linking hypothesis between linguistic representation and cortical computation. PMID:28253256

  8. Hierarchical ZnO with twinned structure: Morphology evolution, formation mechanism and properties

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Ruixia; Song, Xueling; Li, Jia; Yang, Ping, E-mail: mse_yangp@ujn.edu.cn

    2015-04-15

    Various hierarchical ZnO architectures constructed by twinned structures have been synthesized via a trisodium citrate assisted hydrothermal method on a large scale. The probable formation mechanisms of hierarchical ZnO structures with twinned structure were proposed and discussed. The hierarchical ZnO with twinned structures are composed of two hemispheres with a center concave junction to join them together at their waists. The ZnO microspheres with rough surfaces were obtained when the concentration of trisodium citrate is 0.1 M. However, the football-like microspheres consisted of hexagonal nanosheets were formed when adding glycerol into the water, which should be attributed to the slower nucleation and growth rate of nanocrystals. The hamburger-like ZnO with different aspect ratio and nonuniform ZnO microspheres were generated due to the different quantity of initial nuclei and growth units when simply modulating the concentration of trisodium citrate. The surface area of football-like ZnO is about 3.51 times of microspheres composed of irregular particles. However their photocatalytic performances are similar under UV light irradiation, which indicates that pore sizes of the sample have more important influences on the photocatalytic activity. - Highlights: • Hierarchical ZnO constructed by twinned structures have been synthesized. • The formation mechanisms of ZnO with twinned structure were discussed. • Football-like microspheres were obtained due to the slower nucleation and growth. • Hamburger-like ZnO was formed due to the amount of initial nuclei and growth units. • Pore sizes have important effects on the photocatalytic activity of sample.

  9. Superhydrophobic surface based on a coral-like hierarchical structure of ZnO.

    Directory of Open Access Journals (Sweden)

    Jun Wu

    Full Text Available BACKGROUND: Fabrication of superhydrophobic surfaces has attracted much interest in the past decade. The fabrication methods that have been studied are chemical vapour deposition, the sol-gel method, etching technique, electrochemical deposition, the layer-by-layer deposition, and so on. Simple and inexpensive methods for manufacturing environmentally stable superhydrophobic surfaces have also been proposed lately. However, work referring to the influence of special structures on the wettability, such as hierarchical ZnO nanostructures, is rare. METHODOLOGY: This study presents a simple and reproducible method to fabricate a superhydrophobic surface with micro-scale roughness based on zinc oxide (ZnO hierarchical structure, which is grown by the hydrothermal method with an alkaline aqueous solution. Coral-like structures of ZnO were fabricated on a glass substrate with a micro-scale roughness, while the antennas of the coral formed the nano-scale roughness. The fresh ZnO films exhibited excellent superhydrophilicity (the apparent contact angle for water droplet was about 0°, while the ability to be wet could be changed to superhydrophobicity after spin-coating Teflon (the apparent contact angle greater than 168°. The procedure reported here can be applied to substrates consisting of other materials and having various shapes. RESULTS: The new process is convenient and environmentally friendly compared to conventional methods. Furthermore, the hierarchical structure generates the extraordinary solid/gas/liquid three-phase contact interface, which is the essential characteristic for a superhydrophobic surface.

  10. HD-RNAS: An automated hierarchical database of RNA structures

    Directory of Open Access Journals (Sweden)

    Shubhra Sankar eRay

    2012-04-01

    Full Text Available One of the important goals of most biological investigations is to classify and organize the experimental findings so that they are readily useful for deriving generalized rules. Although there is a huge amount of information on RNA structures in PDB, there are redundant files, ambiguous synthetic sequences etc. Moreover, a systematic hierarchical organization, reflecting RNA classification, is missing in PDB. In this investigation, we have classified all the available RNA crystal structures from PDB through a programmatic approach. Hence, it would be now a simple assignment to regularly update the classification as and when new structures are released. The classification can further determine (i a non-redundant set of RNA structures and (ii if available, a set of structures of identical sequence and function, which can highlight structural polymorphism, ligand-induced conformational alterations etc. Presently, we have classified the available structures (2095 PDB entries having RNA chain longer than 9 nucleotides solved by X-ray crystallography or NMR spectroscopy into nine functional classes. The structures of same function and same source are mostly seen to be similar with subtle differences depending on their functional complexation. The web-server is available online at http://www.saha.ac.in/biop/www/HD-RNAS.html and is updated regularly.

  11. Emergence of hierarchical structural complexities in nanoparticles and their assembly

    Science.gov (United States)

    Zeng, Chenjie; Chen, Yuxiang; Kirschbaum, Kristin; Lambright, Kelly J.; Jin, Rongchao

    2016-12-01

    We demonstrate that nanoparticle self-assembly can reach the same level of hierarchy, complexity, and accuracy as biomolecules. The precise assembly structures of gold nanoparticles (246 gold core atoms with 80 p-methylbenzenethiolate surface ligands) at the atomic, molecular, and nanoscale levels were determined from x-ray diffraction studies. We identified the driving forces and rules that guide the multiscale assembly behavior. The protecting ligands self-organize into rotational and parallel patterns on the nanoparticle surface via C-Hṡṡṡπ interaction, and the symmetry and density of surface patterns dictate directional packing of nanoparticles into crystals with orientational, rotational, and translational orders. Through hierarchical interactions and symmetry matching, the simple building blocks evolve into complex structures, representing an emergent phenomenon in the nanoparticle system.

  12. Genomic analysis of the hierarchical structure of regulatory networks

    Science.gov (United States)

    Yu, Haiyuan; Gerstein, Mark

    2006-01-01

    A fundamental question in biology is how the cell uses transcription factors (TFs) to coordinate the expression of thousands of genes in response to various stimuli. The relationships between TFs and their target genes can be modeled in terms of directed regulatory networks. These relationships, in turn, can be readily compared with commonplace “chain-of-command” structures in social networks, which have characteristic hierarchical layouts. Here, we develop algorithms for identifying generalized hierarchies (allowing for various loop structures) and use these approaches to illuminate extensive pyramid-shaped hierarchical structures existing in the regulatory networks of representative prokaryotes (Escherichia coli) and eukaryotes (Saccharomyces cerevisiae), with most TFs at the bottom levels and only a few master TFs on top. These masters are situated near the center of the protein–protein interaction network, a different type of network from the regulatory one, and they receive most of the input for the whole regulatory hierarchy through protein interactions. Moreover, they have maximal influence over other genes, in terms of affecting expression-level changes. Surprisingly, however, TFs at the bottom of the regulatory hierarchy are more essential to the viability of the cell. Finally, one might think master TFs achieve their wide influence through directly regulating many targets, but TFs with most direct targets are in the middle of the hierarchy. We find, in fact, that these midlevel TFs are “control bottlenecks” in the hierarchy, and this great degree of control for “middle managers” has parallels in efficient social structures in various corporate and governmental settings. PMID:17003135

  13. Hybrid Direct Write Lithographic Strategies for Complex Hierarchical Structures

    Science.gov (United States)

    Singer, Jonathan P.

    With the number of alternative lithographic techniques for high resolution and 3D patterning rapidly increasing, there is a need to identify a set of scalable techniques which balances the ability to arbitrarily control every detail of a target pattern and to produce these complex patterns at a high rate. It is in this way that metamaterial devices put forward on a lab scale for applications such as phononics, photonics, and plasmonics can be realized in the industrial scale. This thesis, in approaching this challenge, utilizes combinations of patterning techniques, leveraging the ability for "large" scale alternative lithographic techniques, such as interference lithography or self-assembly, to create the same nanostructured morphology over a large area combined with laser direct write. The process of drawing a single line or isolated voxel can result in a hierarchical pattern defined by the latent motif of the larger-scale technique. The net resuh is to shift the burden of high resolution patterning from the direct write to the large scale technique, effectively decoupling the correlation between the level of detail and the patterning speed and control. More specifically, the following combinations with laser direct writing were investigated: (1) proximity field nanopatterning for the predefinition of diffraction-order-defined 3D resonators which were applied as "stand-up" plasmodic microresonators, (2) dewetting to conduct development-free 2D patterning of isolated sub-micron lines, and, via overlap effects, nanoscale ( <1 00 nm) gratings, (3) block copolymer self-assembly to initiate the simultaneous annealing and alignment of near-equilibrium microdomains from a metastable starting morphology, and (4) interference lithography to fabricate 3D sub-micron periodic and quasiperiodic hierarchical structures with controllable positioning and tunable fill fraction that has potential for applications to microphotonics. In conjunction with the experimental components

  14. The structure of dark matter halos in hierarchical clustering theories

    CERN Document Server

    Subramanian, K; Ostriker, J P; Subramanian, Kandaswamy; Cen, Renyue; Ostriker, Jeremiah P.

    1999-01-01

    During hierarchical clustering, smaller masses generally collapse earlier than larger masses and so are denser on the average. The core of a small mass halo could be dense enough to resist disruption and survive undigested, when it is incorporated into a bigger object. We explore the possibility that a nested sequence of undigested cores in the center of the halo, which have survived the hierarchical, inhomogeneous collapse to form larger and larger objects, determines the halo structure in the inner regions. For a flat universe with $P(k) \\propto k^n$, scaling arguments then suggest that the core density profile is, $\\rho \\propto r^{-\\alpha}$ with $\\alpha = (9+3n)/(5+n)$. But whether such behaviour obtains depends on detailed dynamics. We first examine the dynamics using a fluid approach to the self-similar collapse solutions for the dark matter phase space density, including the effect of velocity dispersions. We highlight the importance of tangential velocity dispersions to obtain density profiles shallowe...

  15. Mesopore quality determines the lifetime of hierarchically structured zeolite catalysts

    Science.gov (United States)

    Milina, Maria; Mitchell, Sharon; Crivelli, Paolo; Cooke, David; Pérez-Ramírez, Javier

    2014-05-01

    Deactivation due to coking limits the lifetime of zeolite catalysts in the production of chemicals and fuels. Superior performance can be achieved through hierarchically structuring the zeolite porosity, yet no relation has been established between the mesopore architecture and the catalyst lifetime. Here we introduce a top-down demetallation strategy to locate mesopores in different regions of MFI-type crystals with identical bulk porous and acidic properties. In contrast, well-established bottom-up strategies as carbon templating and seed silanization fail to yield materials with matching characteristics. Advanced characterization tools capable of accurately discriminating the mesopore size, distribution and connectivity are applied to corroborate the concept of mesopore quality. Positron annihilation lifetime spectroscopy proves powerful to quantify the global connectivity of the intracrystalline pore network, which, as demonstrated in the conversions of methanol or of propanal to hydrocarbons, is closely linked to the lifetime of zeolite catalysts. The findings emphasize the need to aptly tailor hierarchical materials for maximal catalytic advantage.

  16. Uncovering hierarchical data structure in single molecule transport

    Science.gov (United States)

    Wu, Ben H.; Ivie, Jeffrey A.; Johnson, Tyler K.; Monti, Oliver L. A.

    2017-03-01

    Interpretation of single molecule transport data is complicated by the fact that all such data are inherently highly stochastic in nature. Features are often broad, seemingly unstructured and distributed over more than an order of magnitude. However, the distribution contains information necessary for capturing the full variety of processes relevant in nanoscale transport, and a better understanding of its hierarchical structure is needed to gain deeper insight into the physics and chemistry of single molecule electronics. Here, we describe a novel data analysis approach based on hierarchical clustering to aid in the interpretation of single molecule conductance-displacement histograms. The primary purpose of statistically partitioning transport data is to provide avenues for unbiased hypothesis generation in single molecule break junction experiments by revealing otherwise potentially hidden aspects in the conductance data. Our approach is generalizable to the analysis of a wide variety of other single molecule experiments in molecular electronics, as well as in single molecule fluorescence spectroscopy, force microscopy, and ion-channel conductance measurements.

  17. Assembly of CdS Quantum Dots onto Hierarchical TiO2 Structure for Quantum Dots Sensitized Solar Cell Applications

    OpenAIRE

    Syed Mansoor Ali; Mohamed Aslam; W. A. Farooq; Amanullah Fatehmulla; Atif, M

    2015-01-01

    Quantum dot (QD) sensitized solar cells based on Hierarchical TiO2 structure (HTS) consisting of spherical nano-urchins on transparent conductive fluorine doped tin oxide glass substrate is fabricated. The hierarchical TiO2 structure consisting of spherical nano-urchins on transparent conductive fluorine doped tin oxide glass substrate synthesized by hydrothermal route. The CdS quantum dots were grown by the successive ionic layer adsorption and reaction deposition method. The quantum dot sen...

  18. Nanowire-based polypyrrole hierarchical structures synthesized by a two-step electrochemical method.

    Science.gov (United States)

    Ge, Dongtao; Huang, Sanqing; Qi, Rucai; Mu, Jing; Shen, Yuqing; Shi, Wei

    2009-08-03

    A simple two-step electrochemical method is proposed for the synthesis of nanowire-based polypyrrole hierarchical structures. In the first step, microstructured polypyrrole films are prepared by electropolymerization. Then, polypyrrole nanowires are electrodeposited on the surface of the as-synthesized microstructured polypyrrole films. As a result, hierarchical structures of polypyrrole nanowires on polypyrrole microstructures are obtained. The surface wettabilities of the resulting nanowire-based polypyrrole hierarchical structures are examined. It is expected that this two-step method can be developed into a versatile route to produce nanowire-based polypyrrole hierarchical structures with different morphologies and surface properties.

  19. YAP-mediated mechanotransduction regulates osteogenic and adipogenic differentiation of BMSCs on hierarchical structure.

    Science.gov (United States)

    Pan, Houhua; Xie, Youtao; Zhang, Zequan; Li, Kai; Hu, Dandan; Zheng, Xuebin; Fan, Qiming; Tang, Tingting

    2017-04-01

    Hierarchical structure mimicking the natural bone microenvironment has been considered as a promising platform to regulate cell functions. We have previously fabricated hierarchical macropore/nanowire structure and evidence has shown that it can better manipulate the cytoskeleton status and osteogenic performance of osteoblasts. However, how cues of hierarchical structure are translated and ultimately linked to BMSC lineage commitment have still remained elusive, which hinders the accurate knowledge and further development of the hierarchical structure. In this study, bone marrow-derived mesenchymal stem cells (BMSCs) fate on hierarchical structure was investigated as well as the detailed mechanisms. It was shown that well-developed cytoskeleton and focal adhesion were observed for BMSCs on hierarchical structure, which was accompanied by enhanced osteogenic and depressed adipogenic potential. Evidence of increased YAP activity and nuclear translocation were exhibited on hierarchical structure and YAP knockdown inhibited osteogenic differentiation and promoted adipogenic differentiation induced by hierarchical structure. Further remove of cytoskeleton tension inhibited YAP function, which confirmed the key role of YAP-mediated mechanotransduction in the BMSC differentiation. These results together provide information of the stem cell fate commitment on hierarchical structure and a promising approach to design advanced biomaterials by focusing on specific mechanotransduction process.

  20. Hierarchical Structure in Semicrystalline Polymers Tethered to Nanospheres

    KAUST Repository

    Kim, Sung A

    2014-01-28

    We report on structural and dynamic transitions of polymers tethered to nanoparticles. In particular, we use X-ray diffraction, vibrational spectroscopy, and thermal measurements to investigate multiscale structure and dynamic transitions of poly(ethylene glycol) (PEG) chains densely grafted to SiO2 nanoparticles. The approach used for synthesizing these hybrid particles leads to homogeneous SiO2-PEG composites with polymer grafting densities as high as 1.5 chains/nm2, which allows the hybrid materials to exist as self-suspended suspensions with distinct hierarchical structure and thermal properties. On angstrom and nanometer length scales, the tethered PEG chains exhibit more dominant TTG conformations and helix unit cell structure, in comparison to the untethered polymer. The nanoparticle tethered PEG chains are also reported to form extended crystallites on tens of nanometers length scales and to exhibit more stable crystalline structure on small dimensions. On length scales comparable to the size of each hybrid SiO 2-PEG unit, the materials are amorphous presumably as a result of the difficulty fitting the nanoparticle anchors into the PEG crystal lattice. This structural change produces large effects on the thermal transitions of PEG molecules tethered to nanoparticles. © 2014 American Chemical Society.

  1. Control Strategies for Islanded Microgrid using Enhanced Hierarchical Control Structure with Multiple Current-Loop Damping Schemes

    DEFF Research Database (Denmark)

    Han, Yang; Shen, Pan; Zhao, Xin

    2017-01-01

    In this paper, the modeling, controller design, and stability analysis of the islanded microgrid (MG) using enhanced hierarchical control structure with multiple current loop damping schemes is proposed. The islanded MG is consisted of the parallel-connected voltage source inverters using LCL...

  2. Hierarchical Sets: Analyzing Pangenome Structure through Scalable Set Visualizations

    DEFF Research Database (Denmark)

    Pedersen, Thomas Lin

    2017-01-01

    The increase in available microbial genome sequences has resulted in an increase in the size of the pangenomes being analyzed. Current pangenome visualizations are not intended for the pangenome sizes possible today and new approaches are necessary in order to convert the increase in available...... information to increase in knowledge. As the pangenome data structure is essentially a collection of sets we explore the potential for scalable set visualization as a tool for pangenome analysis. We present a new hierarchical clustering algorithm based on set arithmetics that optimizes the intersection sizes...... along the branches. The intersection and union sizes along the hierarchy are visualized using a composite dendrogram and icicle plot, which, in pangenome context, shows the evolution of pangenome and core size along the evolutionary hierarchy. Outlying elements, i.e. elements whose presence pattern do...

  3. Tensegrity I. Cell structure and hierarchical systems biology

    Science.gov (United States)

    Ingber, Donald E.

    2003-01-01

    In 1993, a Commentary in this journal described how a simple mechanical model of cell structure based on tensegrity architecture can help to explain how cell shape, movement and cytoskeletal mechanics are controlled, as well as how cells sense and respond to mechanical forces (J. Cell Sci. 104, 613-627). The cellular tensegrity model can now be revisited and placed in context of new advances in our understanding of cell structure, biological networks and mechanoregulation that have been made over the past decade. Recent work provides strong evidence to support the use of tensegrity by cells, and mathematical formulations of the model predict many aspects of cell behavior. In addition, development of the tensegrity theory and its translation into mathematical terms are beginning to allow us to define the relationship between mechanics and biochemistry at the molecular level and to attack the larger problem of biological complexity. Part I of this two-part article covers the evidence for cellular tensegrity at the molecular level and describes how this building system may provide a structural basis for the hierarchical organization of living systems--from molecule to organism. Part II, which focuses on how these structural networks influence information processing networks, appears in the next issue.

  4. The fragmentation and stability of hierarchical structure in Serpens South

    CERN Document Server

    Friesen, R K; Di Francesco, J; Gutermuth, R; Myers, P C

    2016-01-01

    Filamentary structures are ubiquitous in molecular clouds, and have been recently argued to play an important role in regulating the size and mass of embedded clumps through fragmentation and mass accretion. Here, we reveal the dynamical state and fragmentation of filamentary molecular gas associated with the Serpens South protocluster through analysis of wide (~4 x 4 pc) observations of NH3 (1,1) and (2,2) inversion transitions with the Green Bank Telescope. Detailed modeling of the NH3 lines reveals that the kinematics of the cluster and surrounding filaments are complex. We identify hierarchical structure using a dendrogram analysis of the NH3 emission. The distance between neighbour structures that are embedded within the same parent structure is generally greater than expected from a spherical Jeans analysis, and is in better agreement with cylindrical fragmentation models. The NH3 line width-size relation is flat, and average gas motions are sub- or trans-sonic over all physical scales observed. Subsoni...

  5. Tensegrity I. Cell structure and hierarchical systems biology

    Science.gov (United States)

    Ingber, Donald E.

    2003-01-01

    In 1993, a Commentary in this journal described how a simple mechanical model of cell structure based on tensegrity architecture can help to explain how cell shape, movement and cytoskeletal mechanics are controlled, as well as how cells sense and respond to mechanical forces (J. Cell Sci. 104, 613-627). The cellular tensegrity model can now be revisited and placed in context of new advances in our understanding of cell structure, biological networks and mechanoregulation that have been made over the past decade. Recent work provides strong evidence to support the use of tensegrity by cells, and mathematical formulations of the model predict many aspects of cell behavior. In addition, development of the tensegrity theory and its translation into mathematical terms are beginning to allow us to define the relationship between mechanics and biochemistry at the molecular level and to attack the larger problem of biological complexity. Part I of this two-part article covers the evidence for cellular tensegrity at the molecular level and describes how this building system may provide a structural basis for the hierarchical organization of living systems--from molecule to organism. Part II, which focuses on how these structural networks influence information processing networks, appears in the next issue.

  6. Structural Consistency: Enabling XML Keyword Search to Eliminate Spurious Results Consistently

    CERN Document Server

    Lee, Ki-Hoon; Han, Wook-Shin; Kim, Min-Soo

    2009-01-01

    XML keyword search is a user-friendly way to query XML data using only keywords. In XML keyword search, to achieve high precision without sacrificing recall, it is important to remove spurious results not intended by the user. Efforts to eliminate spurious results have enjoyed some success by using the concepts of LCA or its variants, SLCA and MLCA. However, existing methods still could find many spurious results. The fundamental cause for the occurrence of spurious results is that the existing methods try to eliminate spurious results locally without global examination of all the query results and, accordingly, some spurious results are not consistently eliminated. In this paper, we propose a novel keyword search method that removes spurious results consistently by exploiting the new concept of structural consistency.

  7. Amino acids assisted hydrothermal synthesis of hierarchically structured ZnO with enhanced photocatalytic activities

    Science.gov (United States)

    Guo, Yanxia; Lin, Siwen; Li, Xuan; Liu, Yuping

    2016-10-01

    Novel hierarchically structured ZnO, including rose-like, dandelion-like and flower-like, have been synthesized through a simple hydrothermal process using different amino acids (glutamine, histidine and glycine) as structure-directing agents and urea as deposition agent, followed by subsequent calcination. Amino acids played a crucial role in the formation of hierarchically structured ZnO, and different amino acids could induce different exquisite shapes and assembly ways, as well as more oxygen defects. The prepared hierarchically structured ZnO exhibited excellent photocatalytic activities for the photodegradation of Rhodamine B, which was associated with their special hierarchical structures, large BET surface area and the existence of more oxygen defects. Amino acid-assisted growth mechanism of hierarchically structured ZnO was also discussed.

  8. Interaction of light with hematite hierarchical structures: Experiments and simulations

    Science.gov (United States)

    Distaso, Monica; Zhuromskyy, Oleksander; Seemann, Benjamin; Pflug, Lukas; Mačković, Mirza; Encina, Ezequiel; Taylor, Robin Klupp; Müller, Rolf; Leugering, Günter; Spiecker, Erdmann; Peschel, Ulf; Peukert, Wolfgang

    2017-03-01

    Mesocrystalline particles have been recognized as a class of multifunctional materials with potential applications in different fields. However, the internal organization of nanocomposite mesocrystals and its influence on the final properties have not yet been investigated. In this paper, a novel strategy based on electrodynamic simulations is developed to shed light on how the internal structure of mesocrystals influences their optical properties. In a first instance, a unified design protocol is reported for the fabrication of hematite/PVP particles with different morphologies such as pseudo-cubes, rods-like and apple-like structures and controlled particle size distributions. The optical properties of hematite/PVP mesocrystals are effectively simulated by taking their aggregate and nanocomposite structure into consideration. The superposition T-Matrix approach accounts for the aggregate nature of mesocrystalline particles and validate the effective medium approximation used in the framework of the Mie theory and electromagnetic simulation such as Finite Element Method. The approach described in our paper provides the framework to understand and predict the optical properties of mesocrystals and more general, of hierarchical nanostructured particles.

  9. Hierarchical spatial structure of stream fish colonization and extinction

    Science.gov (United States)

    Hitt, N.P.; Roberts, J.H.

    2012-01-01

    Spatial variation in extinction and colonization is expected to influence community composition over time. In stream fish communities, local species richness (alpha diversity) and species turnover (beta diversity) are thought to be regulated by high extinction rates in headwater streams and high colonization rates in downstream areas. We evaluated the spatiotemporal structure of fish communities in streams originally surveyed by Burton and Odum 1945 (Ecology 26: 182-194) in Virginia, USA and explored the effects of species traits on extinction and colonization dynamics. We documented dramatic changes in fish community structure at both the site and stream scales. Of the 34 fish species observed, 20 (59%) were present in both time periods, but 11 (32%) colonized the study area and three (9%) were extirpated over time. Within streams, alpha diversity increased in two of three streams but beta diversity decreased dramatically in all streams due to fish community homogenization caused by colonization of common species and extirpation of rare species. Among streams, however, fish communities differentiated over time. Regression trees indicated that reproductive life-history traits such as spawning mound construction, associations with mound-building species, and high fecundity were important predictors of species persistence or colonization. Conversely, native fishes not associated with mound-building exhibited the highest rates of extirpation from streams. Our results demonstrate that stream fish colonization and extinction dynamics exhibit hierarchical spatial structure and suggest that mound-building fishes serve as keystone species for colonization of headwater streams.

  10. Decoupled Hierarchical Structures for Suppression of Leidenfrost Phenomenon.

    Science.gov (United States)

    Farokhnia, Nazanin; Sajadi, Seyed Mohammad; Irajizad, Peyman; Ghasemi, Hadi

    2017-03-14

    Thermal management of high temperature systems through cooling droplets is limited by the existence of the Leidenfrost point (LFP), at which the formation of a continuous vapor film between a hot solid and a cooling droplet diminishes the heat transfer rate. This limit results in a bottleneck for the advancement of the wide spectrum of systems including high-temperature power generation, electronics/photonics, reactors, and spacecraft. Despite a long time effort on development of surfaces for suppression of this phenomenon, this limit has only shifted to higher temperatures, but still exists. Here, we report a new multiscale decoupled hierarchical structure that suppress the Leidenfrost state and provide efficient heat dissipation at high temperatures. The architecture of these structures is composed of a nanomembrane assembled on top of a deep micropillar structure. This architecture allows to independently tune the involved forces and to suppress LFP. Once a cooling droplet contacts these surfaces, by rerouting the path of vapor flow, the cooling droplet remains attached to the hot solid substrates even at high temperatures (up to 570 °C) for heat dissipation with no existence of Leidenfrost phenomenon. These new surfaces offer unprecedented heat dissipation capacity at high temperatures (2 orders of magnitude higher than the other state-of-the-art surfaces). We envision that these surfaces open a new avenue in thermal management of high-temperature systems through spray cooling.

  11. Growth Mechanism of a Unique Hierarchical Vaterite Structure

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2013-03-01

    Calcium carbonate is one of the most significant minerals in nature as well as in biogenic sources. Calcium carbonate occurs naturally in three crystalline polymorphs, i.e., calcite, aragonite, and vaterite. Although it has been attracted much research attention to understanding of the formation mechanisms of the material, the properties of the vaterite polymorph is not well known. Here we report synthesis and formation mechanism of a unique hierarchical structure of vaterite. The material is grown by a controlled diffusion method. The structure possesses a core and an outer part. The core is convex lens-like and is formed by vaterite nanocrystals that have small misorientations. The outer part is separated into six garlic clove-like segments. Each segment possesses piles of plate-like vaterite crystals, and the orientations of the plates continuously change from pile to pile. Based on real-time experimental results and the structural analysis, a growth mechanism is presented. Work supported by NSFC (Grant No. 51172104) and MOST of China (Grant No. 2101CB630705)

  12. Generation of Hierarchically Ordered Structures on a Polymer Film by Electrohydrodynamic Structure Formation.

    Science.gov (United States)

    Tian, Hongmiao; Shao, Jinyou; Hu, Hong; Wang, Li; Ding, Yucheng

    2016-06-29

    The extensive applications of hierarchical structures in optoelectronics, micro/nanofluidics, energy conservation, etc., have led to the development of a variety of approaches for their fabrication, which can be categorized as bottom-up or top-down strategies. Current bottom-up and top-down strategies bear a complementary relationship to each other due to their processing characteristics, i.e., the advantages of one method correspond to the disadvantages of the other, and vice versa. Here we propose a novel method based on electrohydrodynamic structure formation, aimed at combining the main advantages of the two strategies. The method allows the fabrication of a hierarchically ordered structure with well-defined geometry and high mechanical durability on a polymer film, through a simple and low-cost process also suitable for mass-production. In this approach, upon application of an electric field between a template and a substrate sandwiching an air gap and a polymer film, the polymer is pulled toward the template and further flows into the template cavities, resulting in a hierarchical structure with primary and secondary patterns determined by electrohydrodynamic instability and by the template features, respectively. In this work, the fabrication of a hierarchical structure by electrohydrodynamic structure formation is studied using numerical simulations and experimental tests. The proposed method is then employed for the one-step fabrication of a hierarchical structure exhibiting a gradual transition in the periodicity of the primary structure using a slant template and a flat polymer film, which presents an excellent performance on controllable wettability.

  13. Frontoparietal Connectivity and Hierarchical Structure of the Brain’s Functional Network during Sleep

    Directory of Open Access Journals (Sweden)

    Victor I Spoormaker

    2012-05-01

    Full Text Available Frontal and parietal regions are associated with some of the most complex cognitive functions, and several frontoparietal resting-state networks can be observed in wakefulness. We used functional magnetic resonance imaging (fMRI data acquired in polysomnographically validated wakefulness, light sleep and slow-wave sleep to examine the hierarchical structure of a low-frequency functional brain network, and to examine whether frontoparietal connectivity would disintegrate in sleep. Whole-brain analyses with hierarchical cluster analysis on predefined atlases were performed, as well as regression of inferior parietal lobules seeds against all voxels in the brain, and an evaluation of the integrity of voxel time-courses in subcortical regions-of-interest. We observed that frontoparietal functional connectivity disintegrated in sleep stage 1 and was absent in deeper sleep stages. Slow-wave sleep was characterized by strong hierarchical clustering of local submodules. Frontoparietal connectivity between inferior parietal lobules and superior medial and right frontal gyrus was lower in sleep stages than in wakefulness. Moreover, thalamus voxels showed maintained integrity in sleep stage 1, making intrathalamic desynchronization an unlikely source of reduced thalamocortical connectivity in this sleep stage. Our data suggest a transition from a globally integrated functional brain network in wakefulness to a disintegrated network consisting of local submodules in slow-wave sleep, in which frontoparietal inter-modular nodes may play a crucial role, possibly in combination with the thalamus.

  14. Category breadth and hierarchical structure in personality: studies of asymmetries in judgments of trait implications.

    Science.gov (United States)

    Hampson, S E; John, O P; Goldberg, L R

    1986-07-01

    Trait breadth and hierarchical organization are central structural principles in personality theory and research. We assume that personality traits serve as categories of behavioral events, and we define the breadth of traits as the diversity of their behavioral manifestations. We show that trait breadth can be measured reliably both by ratings and by direct comparisons within trait pairs. We assess the hierarchical relations between traits differing in breadth, using a task in which subjects select the most meaningful of two statements, such as "To be talkative is a way of being extroverted" versus "To be extroverted is a way of being talkative." The extent of asymmetry in the choices of the subject sample provides an index of the degree of class inclusion. In four studies, we demonstrate that the size of the asymmetry effect is highly predictable from differences in trait breadth, even when the effects of social desirability, familiarity, and meaningfulness are controlled. Moreover, we replicate these findings in two cultural contexts, and even at the level of individual subjects. The availability of traits at different hierarchical levels requires personality psychologists to make an explicit choice about level of abstraction, especially when studying behavioral consistency. We discuss the prospect for identifying a generally preferred or "basic" level of personality description.

  15. Copper oxide assisted cysteine hierarchical structures for immunosensor application

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Chandra Mouli [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India); Sumana, Gajjala, E-mail: sumanagajjala@gmail.com [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Tiwari, Ida [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India)

    2014-09-08

    The present work describes the promising electrochemical immunosensing strategy based on copper (II) assisted hierarchical cysteine structures (CuCys) varying from star to flower like morphology. The CuCys having average size of 10 μm have been synthesised using L-Cysteine as initial precursor in presence of copper oxide under environmentally friendly conditions in aqueous medium. To delineate the synthesis mechanism, detailed structural investigations have been carried out using characterization techniques such as X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The electrochemical behaviour of self-assembled CuCys on gold electrode shows surface controlled electrode reaction with an apparent electron transfer rate constant of 3.38 × 10{sup −4 }cm s{sup −1}. This innovative platform has been utilized to fabricate an immunosensor by covalently immobilizing monoclonal antibodies specific for Escherichia coli O157:H7 (E. coli). Under the optimal conditions, the fabricated immunosensor is found to be sensitive and specific for the detection of E. coli with a detection limit of 10 cfu/ml.

  16. Leveraging hierarchical population structure in discrete association studies.

    Directory of Open Access Journals (Sweden)

    Jonathan Carlson

    Full Text Available Population structure can confound the identification of correlations in biological data. Such confounding has been recognized in multiple biological disciplines, resulting in a disparate collection of proposed solutions. We examine several methods that correct for confounding on discrete data with hierarchical population structure and identify two distinct confounding processes, which we call coevolution and conditional influence. We describe these processes in terms of generative models and show that these generative models can be used to correct for the confounding effects. Finally, we apply the models to three applications: identification of escape mutations in HIV-1 in response to specific HLA-mediated immune pressure, prediction of coevolving residues in an HIV-1 peptide, and a search for genotypes that are associated with bacterial resistance traits in Arabidopsis thaliana. We show that coevolution is a better description of confounding in some applications and conditional influence is better in others. That is, we show that no single method is best for addressing all forms of confounding. Analysis tools based on these models are available on the internet as both web based applications and downloadable source code at http://atom.research.microsoft.com/bio/phylod.aspx.

  17. Hierarchical tubular structures grown from the gel/liquid interface.

    Science.gov (United States)

    Steenbjerg Ibsen, Casper Jon; Mikladal, Bjørn Fridur; Bjørnholt Jensen, Uffe; Birkedal, Henrik

    2014-12-01

    Three dimensional hierarchical materials are widespread in nature but are difficult to synthesize by using self-assembly/organization. Here, we employ a gel-liquid interface to obtain centimeter-long ∼100 μm diameter tubes with complex mineral wall structures that grow from the interface into solution. The gel, made from gelatin, is loaded with metal chloride salt, whereas the solution is a high pH anion source. Tubes were obtained with a range of cations (Ca(2+) , Sr(2+) , Ba(2+) , Cu(2+) , and Zn(2+) ) and anions (CO3 (2-) and PO4 (3-) ). The crystalline phases found in the tube walls corresponded to expectations from solution chemistries and phase solubilities. The growth mechanism is found to be akin to that of chemical gardens. The divalent cations modify the strength of the gelatin gel in a manner that involves not only simple electrostatic screening, but also ion-specific effects. Thus, tubes were not obtained for those ions and/or concentrations that significantly changed the gel's mechanical structure. At high Cu(2+) loading, for example, vertical convection bands, not Liesegang bands, were observed in the gels.

  18. Hierarchical object parsing from structured noisy point clouds.

    Science.gov (United States)

    Barbu, Adrian

    2013-07-01

    Object parsing and segmentation from point clouds are challenging tasks because the relevant data is available only as thin structures along object boundaries or other features, and is corrupted by large amounts of noise. To handle this kind of data, flexible shape models are desired that can accurately follow the object boundaries. Popular models such as active shape and active appearance models (AAMs) lack the necessary flexibility for this task, while recent approaches such as the recursive compositional models make model simplifications to obtain computational guarantees. This paper investigates a hierarchical Bayesian model of shape and appearance in a generative setting. The input data is explained by an object parsing layer which is a deformation of a hidden principal component analysis (PCA) shape model with Gaussian prior. The paper also introduces a novel efficient inference algorithm that uses informed data-driven proposals to initialize local searches for the hidden variables. Applied to the problem of object parsing from structured point clouds such as edge detection images, the proposed approach obtains state-of-the-art parsing errors on two standard datasets without using any intensity information.

  19. Curved hierarchically micro-micro structured polypropylene surfaces by injection molding

    Science.gov (United States)

    Mielonen, K.; Suvanto, M.; Pakkanen, T. A.

    2017-01-01

    Structural hierarchy of polymer surfaces has been of central interest due to its diverse surface functionalities. However, the research on hierarchically structured polymer surfaces has been focused on planar surfaces even though applications may also be variously curved. This study demonstrates the fabrication of curved rigid polymer surfaces with precisely controlled hierarchical microstructures. The surface structuration was made on an aluminum foil with a microworking robot, and polypropylene replicas were produced by injection molding. Depending on the mold structuration procedure, the curved mold can have either radially or vertically oriented structures. Both convex and concave curvatures were here applied to spherically and cylindrically curved surfaces. A simple structure protection technique was applied to support the structures during mechanical bending of the foil. The planar hierarchically microstructured polypropylene surfaces were characterized to exhibit superhydrophobicity, and similar structures were obtained on the curved surfaces. Introducing the curvature to the hierarchically structured surfaces may further widen the applicability of functionalized polymer surfaces.

  20. Transfer printing of 3D hierarchical gold structures using a sequentially imprinted polymer stamp

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Fengxiang; Low, Hong Yee [Institute of Materials Research and Engineering, A-STAR - Agency for Science, Technology and Research, 3 Research Link, 117602 (Singapore)], E-mail: hy-low@imre.a-star.edu.sg

    2008-10-15

    Complex three-dimensional (3D) hierarchical structures on polymeric materials are fabricated through a process referred to as sequential imprinting. In this work, the sequentially imprinted polystyrene film is used as a soft stamp to replicate hierarchical structures onto gold (Au) films, and the Au structures are then transferred to a substrate by transfer printing at an elevated temperature and pressure. Continuous and isolated 3D structures can be selectively fabricated with the assistance of thermo-mechanical deformation of the polymer stamp. Hierarchical Au structures are achieved without the need for a corresponding three-dimensionally patterned mold.

  1. A study of hierarchical structure on South China industrial electricity-consumption correlation

    Science.gov (United States)

    Yao, Can-Zhong; Lin, Ji-Nan; Liu, Xiao-Feng

    2016-02-01

    Based on industrial electricity-consumption data of five southern provinces of China from 2005 to 2013, we study the industrial correlation mechanism with MST (minimal spanning tree) and HT (hierarchical tree) models. First, we comparatively analyze the industrial electricity-consumption correlation structure in pre-crisis and after-crisis period using MST model and Bootstrap technique of statistical reliability test of links. Results exhibit that all industrial electricity-consumption trees of five southern provinces of China in pre-crisis and after-crisis time are in formation of chain, and the "center-periphery structure" of those chain-like trees is consistent with industrial specialization in classical industrial chain theory. Additionally, the industrial structure of some provinces is reorganized and transferred in pre-crisis and after-crisis time. Further, the comparative analysis with hierarchical tree and Bootstrap technique demonstrates that as for both observations of GD and overall NF, the industrial electricity-consumption correlation is non-significant clustered in pre-crisis period, whereas it turns significant clustered in after-crisis time. Therefore we propose that in perspective of electricity-consumption, their industrial structures are directed to optimized organization and global correlation. Finally, the analysis of distance of HTs verifies that industrial reorganization and development may strengthen market integration, coordination and correlation of industrial production. Except GZ, other four provinces have a shorter distance of industrial electricity-consumption correlation in after-crisis period, revealing a better performance of regional specialization and integration.

  2. Developing Dynamic Virtual Environments Using Hierarchical, Tree-Structured Approach

    Directory of Open Access Journals (Sweden)

    Wan Mohd Rizhan Wan Idris

    2011-05-01

    Full Text Available Virtual reality (VR has been utilized in various applications such as in architecture, medicine, advertisement, business, entertainment, and education. In the world of simulation, VR software allows users to visualize, manipulate and interact with the computers and complex data. However, developing VR environments is costly and expensive. Highly-technical persons are needed to create the virtual objects from scratch. Once a virtual system is created, managing and modifying it creates further problems. There is a need for non-technical users to be able to create and modify their own virtual environments. This paper discusses a systematic technique to develop dynamic virtual environments and to manage virtual objects in their virtual environment. The technique is called hierarchical, tree-structured approach. To implement the technique, object-oriented programming language was used such as Java, Java 3D and Java Swing. For the usability and performance of the technique, a virtual environment has been created to become as case study. The tool has been perceived as an easy tool to use, especially for an environment in education.

  3. DEVELOPING DYNAMIC VIRTUAL ENVIRONMENTS USING HIERARCHICAL, TREE-STRUCTURED APPROACH

    Directory of Open Access Journals (Sweden)

    Wan Mohd Rizhan Wan Idris

    2015-10-01

    Full Text Available Virtual reality (VR has been utilized in various applications such as in architecture, medicine, advertisement, business, entertainment, and education. In the world of simulation, VR software allows users to visualize, manipulate and interact with the computers and complex data. However, developing VR environments is costly and expensive. Highly-technical persons are needed to create the virtual objects from scratch. Once a virtual system is created, managing and modifying it creates further problems. There is a need for non-technical users to be able to create and modify their own virtual environments. This paper discusses a systematic technique to develop dynamic virtual environments and to manage virtual objects in their virtual environment. The technique is called hierarchical, tree-structured approach. To implement the technique, object-oriented programming language was used such as Java, Java 3D and Java Swing. For the usability and performance of the technique, a virtual environment has been created to become as case study. The tool has been perceived as an easy tool to use, especially for an environment in education.

  4. SO2 Emissions in China - Their Network and Hierarchical Structures

    Science.gov (United States)

    Yan, Shaomin; Wu, Guang

    2017-04-01

    SO2 emissions lead to various harmful effects on environment and human health. The SO2 emission in China has significant contribution to the global SO2 emission, so it is necessary to employ various methods to study SO2 emissions in China with great details in order to lay the foundation for policymaking to improve environmental conditions in China. Network analysis is used to analyze the SO2 emissions from power generation, industrial, residential and transportation sectors in China for 2008 and 2010, which are recently available from 1744 ground surface monitoring stations. The results show that the SO2 emissions from power generation sector were highly individualized as small-sized clusters, the SO2 emissions from industrial sector underwent an integration process with a large cluster contained 1674 places covering all industrial areas in China, the SO2 emissions from residential sector was not impacted by time, and the SO2 emissions from transportation sector underwent significant integration. Hierarchical structure is obtained by further combining SO2 emissions from all four sectors and is potentially useful to find out similar patterns of SO2 emissions, which can provide information on understanding the mechanisms of SO2 pollution and on designing different environmental measure to combat SO2 emissions.

  5. Bayesian structural equation modeling method for hierarchical model validation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Xiaomo [Department of Civil and Environmental Engineering, Vanderbilt University, Box 1831-B, Nashville, TN 37235 (United States)], E-mail: xiaomo.jiang@vanderbilt.edu; Mahadevan, Sankaran [Department of Civil and Environmental Engineering, Vanderbilt University, Box 1831-B, Nashville, TN 37235 (United States)], E-mail: sankaran.mahadevan@vanderbilt.edu

    2009-04-15

    A building block approach to model validation may proceed through various levels, such as material to component to subsystem to system, comparing model predictions with experimental observations at each level. Usually, experimental data becomes scarce as one proceeds from lower to higher levels. This paper presents a structural equation modeling approach to make use of the lower-level data for higher-level model validation under uncertainty, integrating several components: lower-level data, higher-level data, computational model, and latent variables. The method proposed in this paper uses latent variables to model two sets of relationships, namely, the computational model to system-level data, and lower-level data to system-level data. A Bayesian network with Markov chain Monte Carlo simulation is applied to represent the two relationships and to estimate the influencing factors between them. Bayesian hypothesis testing is employed to quantify the confidence in the predictive model at the system level, and the role of lower-level data in the model validation assessment at the system level. The proposed methodology is implemented for hierarchical assessment of three validation problems, using discrete observations and time-series data.

  6. The Emergence of Hierarchical Structure in Human Language

    Directory of Open Access Journals (Sweden)

    Shigeru eMiyagawa

    2013-02-01

    Full Text Available We propose a novel account for the emergence of human language syntax. Like many evolutionary innovations, language arose from the adventitious combination of two pre-existing, simpler systems that had been evolved for other functional tasks. The first system, Type E(xpression, is found in birdsong, where it marks territory, mating availability, and similar ‘expressive’ functions. The second system, Type L(exical, has been suggestively found in non-human primate calls and in honeybee waggle dances, where it demarcates predicates with one or more ‘arguments,’ such as combinations of calls in monkeys or compass headings set to sun position in honeybees. We show that human language syntax is composed of two layers that parallel these two independently evolved systems: an E layer resembling the Type E system of birdsong and an L layer providing words. The existence of the E and L layers can be confirmed using standard linguistic methodology. Each layer, E and L, when considered separately, are characterizable as finite state systems, as observed in several non-human species. When the two systems are put together they interact, yielding the unbounded, non-finite state, hierarchical structure that serves as the hallmark of ful

  7. Hierarchical Structure of the Eysenck Personality Inventory in a Large Population Sample: Goldberg's Trait-Tier Mapping Procedure.

    Science.gov (United States)

    Chapman, Benjamin P; Weiss, Alexander; Barrett, Paul; Duberstein, Paul

    2013-03-01

    The structure of the Eysenck Personality Inventory (EPI) is poorly understood, and applications have mostly been confined to the broad Neuroticism, Extraversion, and Lie scales. Using a hierarchical factoring procedure, we mapped the sequential differentiation of EPI scales from broad, molar factors to more specific, molecular factors, in a UK population sample of over 6500 persons. Replicable facets at the lowest tier of Neuroticism included emotional fragility, mood lability, nervous tension, and rumination. The lowest order set of replicable Extraversion facets consisted of social dynamism, sociotropy, decisiveness, jocularity, social information seeking, and impulsivity. The Lie scale consisted of an interpersonal virtue and a behavioral diligence facet. Users of the EPI may be well served in some circumstances by considering its broad Neuroticism, Extraversion, and Lie scales as multifactorial, a feature that was explicitly incorporated into subsequent Eysenck inventories and is consistent with other hierarchical trait structures.

  8. HIERARCHICAL STRUCTURE IN ADL AND IADL - ANALYTICAL ASSUMPTIONS AND APPLICATIONS FOR CLINICIAN AND RESEARCHERS

    NARCIS (Netherlands)

    KEMPEN, GIJM; MYERS, AM; POWELL, LE

    1995-01-01

    The results of a Canadian study have shown that a set of 12 (I)ADL items did not meet the criteria of Guttman's scalogram program, questioning the assumption of hierarchical ordering. In this article, the hierarchical structure of (I)ADL items from the Canadian elderly sample is retested with anothe

  9. Hierarchical modeling and its numerical implementation for layered thin elastic structures

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jin-Rae [Hongik University, Sejong (Korea, Republic of)

    2017-05-15

    Thin elastic structures such as beam- and plate-like structures and laminates are characterized by the small thickness, which lead to classical plate and laminate theories in which the displacement fields through the thickness are assumed linear or higher-order polynomials. These classical theories are either insufficient to represent the complex stress variation through the thickness or may encounter the accuracy-computational cost dilemma. In order to overcome the inherent problem of classical theories, the concept of hierarchical modeling has been emerged. In the hierarchical modeling, the hierarchical models with different model levels are selected and combined within a structure domain, in order to make the modeling error be distributed as uniformly as possible throughout the problem domain. The purpose of current study is to explore the potential of hierarchical modeling for the effective numerical analysis of layered structures such as laminated composite. For this goal, the hierarchical models are constructed and the hierarchical modeling is implemented by selectively adjusting the level of hierarchical models. As well, the major characteristics of hierarchical models are investigated through the numerical experiments.

  10. Self-consistent modelling of resonant tunnelling structures

    DEFF Research Database (Denmark)

    Fiig, T.; Jauho, A.P.

    1992-01-01

    We report a comprehensive study of the effects of self-consistency on the I-V-characteristics of resonant tunnelling structures. The calculational method is based on a simultaneous solution of the effective-mass Schrödinger equation and the Poisson equation, and the current is evaluated with the ......We report a comprehensive study of the effects of self-consistency on the I-V-characteristics of resonant tunnelling structures. The calculational method is based on a simultaneous solution of the effective-mass Schrödinger equation and the Poisson equation, and the current is evaluated...... applied voltages and carrier densities at the emitter-barrier interface. We include the two-dimensional accumulation layer charge and the quantum well charge in our self-consistent scheme. We discuss the evaluation of the current contribution originating from the two-dimensional accumulation layer charges...

  11. Structures, profile consistency, and transport scaling in electrostatic convection

    DEFF Research Database (Denmark)

    Bian, N.H.; Garcia, O.E.

    2005-01-01

    that for interchange modes, profile consistency is in fact due to mixing by persistent large-scale convective cells. This mechanism is not a turbulent diffusion, cannot occur in collisionless systems, and is the analog of the well-known laminar "magnetic flux expulsion" in magneiohydrodynamics. This expulsion process...... involves a "pinch" across closed streamlines and further results in the formation of pressure fingers along the-separatrix of the convective cells. By nature, these coherent structures are dissipative because the mixing process that leads to their formation relies on a finite amount of collisional...... diffusion. Numerical simulations of two-dimensional interchange modes confirm the role of laminar expulsion by convective cells, for profile consistency and structure formation. They also show that the fingerlike pressure structures ultimately control the rate of heat transport across the plasma layer...

  12. Fabrication of micro/nano hierarchical structures with analysis on the surface mechanics

    Science.gov (United States)

    Jheng, Yu-Sheng; Lee, Yeeu-Chang

    2016-10-01

    Biomimicry refers to the imitation of mechanisms and features found in living creatures using artificial methods. This study used optical lithography, colloidal lithography, and dry etching to mimic the micro/nano hierarchical structures covering the soles of gecko feet. We measured the static contact angle and contact angle hysteresis to reveal the behavior of liquid drops on the hierarchical structures. Pulling tests were also performed to measure the resistance of movement between the hierarchical structures and a testing plate. Our results reveal that hierarchical structures at the micro-/nano-scale are considerably hydrophobic, they provide good flow characteristics, and they generate more contact force than do surfaces with micro-scale cylindrical structures.

  13. SHIPS: Spectral Hierarchical clustering for the Inference of Population Structure in genetic studies.

    Science.gov (United States)

    Bouaziz, Matthieu; Paccard, Caroline; Guedj, Mickael; Ambroise, Christophe

    2012-01-01

    Inferring the structure of populations has many applications for genetic research. In addition to providing information for evolutionary studies, it can be used to account for the bias induced by population stratification in association studies. To this end, many algorithms have been proposed to cluster individuals into genetically homogeneous sub-populations. The parametric algorithms, such as Structure, are very popular but their underlying complexity and their high computational cost led to the development of faster parametric alternatives such as Admixture. Alternatives to these methods are the non-parametric approaches. Among this category, AWclust has proven efficient but fails to properly identify population structure for complex datasets. We present in this article a new clustering algorithm called Spectral Hierarchical clustering for the Inference of Population Structure (SHIPS), based on a divisive hierarchical clustering strategy, allowing a progressive investigation of population structure. This method takes genetic data as input to cluster individuals into homogeneous sub-populations and with the use of the gap statistic estimates the optimal number of such sub-populations. SHIPS was applied to a set of simulated discrete and admixed datasets and to real SNP datasets, that are data from the HapMap and Pan-Asian SNP consortium. The programs Structure, Admixture, AWclust and PCAclust were also investigated in a comparison study. SHIPS and the parametric approach Structure were the most accurate when applied to simulated datasets both in terms of individual assignments and estimation of the correct number of clusters. The analysis of the results on the real datasets highlighted that the clusterings of SHIPS were the more consistent with the population labels or those produced by the Admixture program. The performances of SHIPS when applied to SNP data, along with its relatively low computational cost and its ease of use make this method a promising

  14. Superior water repellency of water strider legs with hierarchical structures: experiments and analysis.

    Science.gov (United States)

    Feng, Xi-Qiao; Gao, Xuefeng; Wu, Ziniu; Jiang, Lei; Zheng, Quan-Shui

    2007-04-24

    Water striders are a type of insect with the remarkable ability to stand effortlessly and walk quickly on water. This article reports the water repellency mechanism of water strider legs. Scanning electron microscope (SEM) observations reveal the uniquely hierarchical structure on the legs, consisting of numerous oriented needle-shaped microsetae with elaborate nanogrooves. The maximal supporting force of a single leg against water surprisingly reaches up to 152 dynes, about 15 times the total body weight of this insect. We theoretically demonstrate that the cooperation of nanogroove structures on the oriented microsetae, in conjunction with the wax on the leg, renders such water repellency. This finding might be helpful in the design of innovative miniature aquatic devices and nonwetting materials.

  15. Superhydrophobic hierarchical structures produced through novel low-cost stamp fabrication and hot embossing of thermoplastic film

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Chae Hee; Han, Sol Yi; Kim, Kwang; Kim, Wook Bae [Korea Polytechnic University, Siheung (Korea, Republic of); Eo, Jae Dong [SNDENG Co., Ltd., Ansan (Korea, Republic of)

    2015-11-15

    We present a simple and cost-effective method to produce super hydrophobic surfaces in thermoplastic polymer substrates, which contain hierarchical micro/nano structures that resemble lotus leaves. The method involved the fabrication of an Al stamp through the sequential application of laser ablation and anodization to create micro- and nano-structures, respectively. The fabricated patterns on the Al stamp were replicated on the thermoplastic Cyclic olefin copolymer (COC) film surfaces through a hot embossing technique. Static water contact angles were measured to evaluate the hydrophobicity of the patterned COC surfaces. The static water contact angle on the micro/nano hierarchical structured COC surface was measured to be 162.3 .deg. on average. The hot embossing process was repeated 31 times with a nano-structured Al stamp, and the replicated COC surfaces showed consistent water contact angles.

  16. Chemical-mechanical stability of the hierarchical structure of shell nacre

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The hierarchical structure and mechanical property of shell nacre are experimentally investigated from the new aspects of chemical stability and chemistry-mechanics coupling. Through chemical deproteinization or demineralization methods together with characterization techniques at micro/nano scales,it is found that the nacre of abalone,haliotis discus hannai,contains a hierarchical structure stacked with irregular aragonite platelets and interplatelet organic matrix thin layers. Yet the aragonite platelet itself is a nanocomposite consisting of nanoparticles and intraplatelet organic matrix framework. The mean diameter of the nanoparticles and the distribution of framework are quite different for different platelets. Though the interplatelet and in-traplatelet organic matrix can be both decomposed by sodium hydroxide solution,the chemical stability of individual aragonite platelets is much higher than that of the microstructure stacked with them. Further,macroscopic bending test or nanoindentation experiment is performed on the micro/nanostructure of nacre after sodium hydroxide treatment. It is found that the Young’s modulus of both the stacked microstructure and nanocomposite platelet reduced. The reduction of the microstructure is more remark than that of the platelet. Therefore the chemical-mechanical stability of the nanocomposite platelet itself is much higher than that of the stacked microstructure of nacre.

  17. The contribution of reinforcement sensitivity to the personality-psychopathology hierarchical structure in childhood and adolescence.

    Science.gov (United States)

    Slobodskaya, Helena R

    2016-11-01

    This study examined the contribution of reinforcement sensitivity to the hierarchical structure of child personality and common psychopathology in community samples of parent reports of children aged 2-18 (N = 968) and self-reports of adolescents aged 10-18 (N = 1,543) using the Inventory of Child Individual Differences-Short version (ICID-S), the Strengths and Difficulties Questionnaire (SDQ), and the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ). A joint higher-order factor analysis of the ICID-S and SDQ scales suggested a 4-factor solution; congruence coefficients indicated replicability of the factors across the 2 samples at all levels of the personality-psychopathology hierarchy. The canonical correlation analyses indicated that reinforcement sensitivity and personality-psychopathology dimensions shared much of their variance. The main contribution of reinforcement sensitivity was through opposing effects of reward and punishment sensitivities. The superordinate factors Beta and Internalizing were best predicted by reinforcement sensitivity, followed by the Externalizing and Positive personality factors. These findings provide evidence for consistency of the hierarchical structure of personality and common psychopathology across informants and highlight the role of reinforcement systems in the development of normal and abnormal patterns of behavior and affect. (PsycINFO Database Record

  18. Building Algebra Testlets: A Comparison of Hierarchical and Linear Structures.

    Science.gov (United States)

    Wainer, Howard; And Others

    1991-01-01

    Hierarchical (adaptive) and linear methods of testlet construction were compared. The performance of 2,080 ninth and tenth graders on a 4-item testlet was used to predict performance on the entire test. The adaptive test was slightly superior as a predictor, but the cost of obtaining that superiority was considerable. (SLD)

  19. Building Algebra Testlets: A Comparison of Hierarchical and Linear Structures.

    Science.gov (United States)

    Wainer, Howard; And Others

    1991-01-01

    Hierarchical (adaptive) and linear methods of testlet construction were compared. The performance of 2,080 ninth and tenth graders on a 4-item testlet was used to predict performance on the entire test. The adaptive test was slightly superior as a predictor, but the cost of obtaining that superiority was considerable. (SLD)

  20. Hierarchical Data Structures in Adventure Education and Therapy

    Science.gov (United States)

    Russell, Keith; Sibthorp, Jim

    2004-01-01

    Hierarchical linear modeling (HIM) is an approach used in data analysis to better understand how program outcomes are affected by the "nested" nature of data collected in many studies. An outcome can be considered variables such as an individual's self-efficacy, social skills, or more targeted outcomes such as demonstrated reading and mathematical…

  1. Web Application for Hierarchical Organizational Structure Optimization – Human Resource Management Case Study

    Directory of Open Access Journals (Sweden)

    Kofjač Davorin

    2015-08-01

    Full Text Available Background and Purpose: In a complex strictly hierarchical organizational structure, undesired oscillations may occur, which have not yet been adequately addressed. Therefore, parameter values, which define fluctuations and transitions from one state to another, need to be optimized to prevent oscillations and to keep parameter values between lower and upper bounds. The objective was to develop a simulation model of hierarchical organizational structure as a web application to help in solving the aforementioned problem.

  2. Resolution of Singularities Introduced by Hierarchical Structure in Deep Neural Networks.

    Science.gov (United States)

    Nitta, Tohru

    2016-06-30

    We present a theoretical analysis of singular points of artificial deep neural networks, resulting in providing deep neural network models having no critical points introduced by a hierarchical structure. It is considered that such deep neural network models have good nature for gradient-based optimization. First, we show that there exist a large number of critical points introduced by a hierarchical structure in deep neural networks as straight lines, depending on the number of hidden layers and the number of hidden neurons. Second, we derive a sufficient condition for deep neural networks having no critical points introduced by a hierarchical structure, which can be applied to general deep neural networks. It is also shown that the existence of critical points introduced by a hierarchical structure is determined by the rank and the regularity of weight matrices for a specific class of deep neural networks. Finally, two kinds of implementation methods of the sufficient conditions to have no critical points are provided. One is a learning algorithm that can avoid critical points introduced by the hierarchical structure during learning (called avoidant learning algorithm). The other is a neural network that does not have some critical points introduced by the hierarchical structure as an inherent property (called avoidant neural network).

  3. Hierarchical structure and cytocompatibility of fish scales from Carassius auratus

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zhou [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wang, Yukun [State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100084 (China); Feng, Qingling, E-mail: biomater@mail.tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory of Advanced Materials of Ministry of Education of China, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Kienzle, Arne; Müller, Werner E.G. [Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Johannes Gutenberg-Universität, Duesbergweg 6, Mainz 55099 (Germany)

    2014-10-01

    To study the structure and the cytocompatibility of fish scales from Carassius auratus, scanning electron microscopy (SEM) was used to observe the morphology of fish scales treated with different processing methods. Based on varying morphologies and components, the fish scales can be divided into three regions on the surface and three layers in vertical. The functions of these three individual layers were analyzed. SEM results show that the primary inorganic components are spherical or cubic hydroxyapatite (HA) nanoparticles. The fish scales have an ∼ 60° overlapped plywood structure of lamellas in the fibrillary plate. The plywood structure consists of co-aligned type I collagen fibers, which are parallel to the HA lamellas. X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and Fourier transform infrared (FTIR) analysis indicate that the main components are HA and type I collagen fibers. MC3T3-E1 cell culture results show a high cytocompatibility and the ability to guide cell proliferation and migration along the scale ridge channels of the fish scales. This plywood structure provides inspiration for a structure-enhanced composite material. - Highlights: • The Carassius auratus fish scale can be divided into 3 layers rather than 2. • The functions of these three individual layers were firstly analyzed. • The fish scale shows a high cytocompatibility. • The fish scale can guide cells migration along the scale ridge channels.

  4. The structure of dust aggregates in hierarchical coagulation

    CERN Document Server

    Dominik, Carsten; Borel, Herman

    2016-01-01

    Dust coagulation in interstellar space and protoplanetary disks is usually treated as one of 2 extreme cases: Particle-Cluster Aggregation and Cluster-Cluster Aggregation. In this paper we study the process of hierarchical growth, where aggregates are built from significantly smaller aggregates (but not monomers). We show that this process can be understood as a modified, PCA-like process that produces porous, but non-fractal particles whose filling factor is chiefly determined by the porosity of the building blocks. We also show that in a coagulation environment where relative velocities are driven by turbulence, a logarithmically flat mass distribution (equal mass per mass decade) as it is typically found in environments where fragmentation replenishes small grains, leads to a situation where small particles and aggregates dominate the growth of large ones. Therefore, in such environments, hierarchical growth should be seen as the norm. Consequently, we predict that the aggregates in such environments are n...

  5. Quasar Evolution Driven by Galaxy Encounters in Hierarchical Structures

    CERN Document Server

    Menci, N; Fontana, A; Giallongo, E; Poli, F; Vittorini, V

    2003-01-01

    We link the evolution of the galaxies in the hierarchical clustering scenario with the changing accretion rates of cold gas onto the central massive black holes that power the quasars. We base on galaxy interactions as main triggers of accretion; the related scaling laws are taken up from Cavaliere & Vittorini (2000), and grafted to a semi-analytic code for galaxy formation. As a result, at high $z$ the protogalaxies grow rapidly by hierarchical merging; meanwhile, much fresh gas is imported and also destabilized, so the holes are fueled at their full Eddington rates. At lower $z$ the galactic dynamical events are mostly encounters in hierarchically growing groups; now the refueling peters out, as the residual gas is exhausted while the destabilizing encounters dwindle. So, with no parameter tuning other than needed for stellar observables, our model uniquely produces at $z>3$ a rise, and at $z\\lesssim 2.5 $ a decline of the bright quasar population as steep as observed. In addition, our results closely f...

  6. Constrained hierarchical least square nonlinear equation solvers. [for indefinite stiffness and large structural deformations

    Science.gov (United States)

    Padovan, J.; Lackney, J.

    1986-01-01

    The current paper develops a constrained hierarchical least square nonlinear equation solver. The procedure can handle the response behavior of systems which possess indefinite tangent stiffness characteristics. Due to the generality of the scheme, this can be achieved at various hierarchical application levels. For instance, in the case of finite element simulations, various combinations of either degree of freedom, nodal, elemental, substructural, and global level iterations are possible. Overall, this enables a solution methodology which is highly stable and storage efficient. To demonstrate the capability of the constrained hierarchical least square methodology, benchmarking examples are presented which treat structure exhibiting highly nonlinear pre- and postbuckling behavior wherein several indefinite stiffness transitions occur.

  7. Template-free synthesis of hierarchical TiO2 structures and their application in dye-sensitized solar cells.

    Science.gov (United States)

    Shao, Fang; Sun, Jing; Gao, Lian; Yang, Songwang; Luo, Jianqiang

    2011-06-01

    We demonstrate here the synthesis of a hierarchical TiO(2) architecture without any surfactants or templates. Two kinds of structure existed simultaneously, the ordered nanoarrays at bottom provided direct conduction pathway for photo generated electrons, while the upper micro-flowers consisted of nanobelt as building units increased the light harvesting ability as the scattering part. The formation mechanism of the hierarchical architecture has been proposed by studying the morphology evolution processes upon reaction time. The performance of dye-sensitized solar cells based on the obtained hierarchical anatase TiO(2) has been also studied, giving a J(SC) = 12.44 mA cm(-2), V(OC) = 0.64 V, FF = 69.05%, and η = 5.53%, which is superior than commercial TiO(2) (P25). The UV-vis results prove that the obtained morphology is beneficial to light-scattering and thus increases the light harvesting ability. This hierarchical TiO(2) structure offers great potential for the development of high-efficiency DSSCs. © 2011 American Chemical Society

  8. 3D Nearest Neighbour Search Using a Clustered Hierarchical Tree Structure

    DEFF Research Database (Denmark)

    Suhaibah, A.; Uznir, U.; Antón Castro, Francesc/François

    2016-01-01

    , with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our...... findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results...... of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN) analysis. It uses a point location and identifies the surrounding neighbours. However...

  9. Hierarchical structural control of visual properties in self-assembled photonic-plasmonic pigments

    CERN Document Server

    Koay, Natalie; Kay, Theresa M; Nerger, Bryan A; Miles-Rossouw, Malaika; Shirman, Tanya; Vu, Thy L; England, Grant; Phillips, Katherine R; Utech, Stefanie; Vogel, Nicolas; Kolle, Mathias; Aizenberg, Joanna

    2014-01-01

    We present a simple one-pot co-assembly method for the synthesis of hierarchically structured pigment particles consisting of silica inverse-opal bricks that are doped with plasmonic absorbers. We study the interplay between the plasmonic and photonic resonances and their effect on the visual appearance of macroscopic collections of photonic bricks that are distributed in randomized orientations. Manipulating the pore geometry tunes the wavelength- and angle-dependence of the scattering profile, which can be engineered to produce angle-dependent Bragg resonances that can either enhance or contrast with the color produced by the plasmonic absorber. By controlling the overall dimensions of the photonic bricks and their aspect ratios, their preferential alignment can either be encouraged or suppressed. This causes the Bragg resonance to appear either as uniform color travel in the former case or as sparse iridescent sparkle in the later case. By manipulating the surface chemistry of these photonic bricks, which ...

  10. Configuration of Self-consistent Flows in a Hole Structure

    Science.gov (United States)

    Hasegawa, Hiroki; Ishiguro, Seiji

    2016-10-01

    Self-consistent particle flows in a hole structure have been studied with a three dimensional electrostatic plasma particle simulation code. In our previous study, we investigated kinetic effects on plasma blob dynamics with the particle simulation code. In this study, we have improved the code in order to investigate the hole propagation dynamics. Here, the hole is the intermittent filamentary structure along the magnetic field line in peripheral plasmas of fusion magnetic confinement devices and the plasma density in the hole is lower than that of background plasma. In the simulation, a hole structure is initially set as a cylindrical form elongated between both end plates and propagates in the grad-B direction. The simulation confirms that a spiral current system is formed in a hole structure. Further, the investigation into the effect of impurities on the flow configuration will be reported. Supported by NIFS Collaboration Research programs (NIFS15KNSS058, NIFS14KNXN279, NIFS15KNTS039, NIFS15KNTS040, and NIFS16KNTT038).

  11. INFOGRAPHIC MODELING OF THE HIERARCHICAL STRUCTURE OF THE MANAGEMENT SYSTEM EXPOSED TO AN INNOVATIVE CONFLICT

    OpenAIRE

    Chulkov Vitaliy Olegovich; Rakhmonov Emomali Karimovich; Kas'yanov Vitaliy Fedorovich; Gusakova Elena Aleksandrovna

    2012-01-01

    This article deals with the infographic modeling of hierarchical management systems exposed to innovative conflicts. The authors analyze the facts that serve as conflict drivers in the construction management environment. The reasons for innovative conflicts include changes in hierarchical structures of management systems, adjustment of workers to new management conditions, changes in the ideology, etc. Conflicts under consideration may involve contradictions between requests placed by custom...

  12. Improved Bio-inspired Artificial Gecko Adhesive by Using Hierarchical Fibrillar Structures

    OpenAIRE

    Li, Yasong

    2014-01-01

    Geckos are well known for being rapid climbers that have long existed in nature. The reversible and reusable adhesive on their feet intrigues scientists to explore a bio-mimetic adhesive, which inherits the adhesion properties of the gecko’s adhesives. Recent advances in electron microscopy reveal the secret of gecko’s climbing ability: there are hierarchical fibrillar structures branching from the skin of their climbing feet. Sizes of these hierarchical fibrils range from micrometer to nanom...

  13. Hydrothermal Fabrication of WO3 Hierarchical Architectures: Structure, Growth and Response

    Directory of Open Access Journals (Sweden)

    Chuan-Sheng Wu

    2015-07-01

    Full Text Available Recently hierarchical architectures, consisting of two-dimensional (2D nanostructures, are of great interest for potential applications in energy and environmental. Here, novel rose-like WO3 hierarchical architectures were successfully synthesized via a facile hydrothermal method. The as-prepared WO3 hierarchical architectures were in fact assembled by numerous nanosheets with an average thickness of ~30 nm. We found that the oxalic acid played a significant role in governing morphologies of WO3 during hydrothermal process. Based on comparative studies, a possible formation mechanism was also proposed in detail. Furthermore, gas-sensing measurement showed that the well-defined 3D WO3 hierarchical architectures exhibited the excellent gas sensing properties towards CO.

  14. A novel method for a multi-level hierarchical composite with brick-and-mortar structure.

    Science.gov (United States)

    Brandt, Kristina; Wolff, Michael F H; Salikov, Vitalij; Heinrich, Stefan; Schneider, Gerold A

    2013-01-01

    The fascination for hierarchically structured hard tissues such as enamel or nacre arises from their unique structure-properties-relationship. During the last decades this numerously motivated the synthesis of composites, mimicking the brick-and-mortar structure of nacre. However, there is still a lack in synthetic engineering materials displaying a true hierarchical structure. Here, we present a novel multi-step processing route for anisotropic 2-level hierarchical composites by combining different coating techniques on different length scales. It comprises polymer-encapsulated ceramic particles as building blocks for the first level, followed by spouted bed spray granulation for a second level, and finally directional hot pressing to anisotropically consolidate the composite. The microstructure achieved reveals a brick-and-mortar hierarchical structure with distinct, however not yet optimized mechanical properties on each level. It opens up a completely new processing route for the synthesis of multi-level hierarchically structured composites, giving prospects to multi-functional structure-properties relationships.

  15. Page Layout Analysis of the Document Image Based on the Region Classification in a Decision Hierarchical Structure

    Directory of Open Access Journals (Sweden)

    Hossein Pourghassem

    2010-10-01

    Full Text Available The conversion of document image to its electronic version is a very important problem in the saving, searching and retrieval application in the official automation system. For this purpose, analysis of the document image is necessary. In this paper, a hierarchical classification structure based on a two-stage segmentation algorithm is proposed. In this structure, image is segmented using the proposed two-stage segmentation algorithm. Then, the type of the image regions such as document and non-document image is determined using multiple classifiers in the hierarchical classification structure. The proposed segmentation algorithm uses two algorithms based on wavelet transform and thresholding. Texture features such as correlation, homogeneity and entropy that extracted from co-occurrenc matrix and also two new features based on wavelet transform are used to classifiy and lable the regions of the image. The hierarchical classifier is consisted of two Multilayer Perceptron (MLP classifiers and a Support Vector Machine (SVM classifier. The proposed algorithm is evaluated on a database consisting of document and non-document images that provides from Internet. The experimental results show the efficiency of the proposed approach in the region segmentation and classification. The proposed algorithm provides accuracy rate of 97.5% on classification of the regions.

  16. Organizational and Spatial Dynamics of Attentional Focusing in Hierarchically Structured Objects

    Science.gov (United States)

    Yeari, Menahem; Goldsmith, Morris

    2011-01-01

    Is the focusing of visual attention object-based, space-based, both, or neither? Attentional focusing latencies in hierarchically structured compound-letter objects were examined, orthogonally manipulating global size (larger vs. smaller) and organizational complexity (two-level structure vs. three-level structure). In a dynamic focusing task,…

  17. Obstacle Avoidance of a Mobile Robot with Hierarchical Structure

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chan Gyu [Yeungnam College of Science and Technolgy, Taegu (Korea)

    2001-06-01

    This paper proposed a new hierarchical fuzzy-neural network algorithm for navigation of a mobile robot within unknown dynamic environment. Proposed navigation algorithm used the learning ability of the neural network and the feasibility of control highly nonlinear system of fuzzy theory. The proposed navigation algorithm used fuzzy algorithm for goal approach and fuzzy-network for effective collision avoidance. Some computer simulation results for a mobile robot equipped with ultrasonic range sensors show that the suggested navigation algorithm is very effective to escape in stationary and moving obstacles environment. (author). 11 refs., 14 figs., 2 tabs.

  18. Estimating the Term Structure With a Semiparametric Bayesian Hierarchical Model: An Application to Corporate Bonds1

    Science.gov (United States)

    Cruz-Marcelo, Alejandro; Ensor, Katherine B.; Rosner, Gary L.

    2011-01-01

    The term structure of interest rates is used to price defaultable bonds and credit derivatives, as well as to infer the quality of bonds for risk management purposes. We introduce a model that jointly estimates term structures by means of a Bayesian hierarchical model with a prior probability model based on Dirichlet process mixtures. The modeling methodology borrows strength across term structures for purposes of estimation. The main advantage of our framework is its ability to produce reliable estimators at the company level even when there are only a few bonds per company. After describing the proposed model, we discuss an empirical application in which the term structure of 197 individual companies is estimated. The sample of 197 consists of 143 companies with only one or two bonds. In-sample and out-of-sample tests are used to quantify the improvement in accuracy that results from approximating the term structure of corporate bonds with estimators by company rather than by credit rating, the latter being a popular choice in the financial literature. A complete description of a Markov chain Monte Carlo (MCMC) scheme for the proposed model is available as Supplementary Material. PMID:21765566

  19. Assembly of CdS Quantum Dots onto Hierarchical TiO2 Structure for Quantum Dots Sensitized Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Syed Mansoor Ali

    2015-05-01

    Full Text Available Quantum dot (QD sensitized solar cells based on Hierarchical TiO2 structure (HTS consisting of spherical nano-urchins on transparent conductive fluorine doped tin oxide glass substrate is fabricated. The hierarchical TiO2 structure consisting of spherical nano-urchins on transparent conductive fluorine doped tin oxide glass substrate synthesized by hydrothermal route. The CdS quantum dots were grown by the successive ionic layer adsorption and reaction deposition method. The quantum dot sensitized solar cell based on the hierarchical TiO2 structure shows a current density JSC = 1.44 mA, VOC = 0.46 V, FF = 0.42 and η = 0.27%. The QD provide a high surface area and nano-urchins offer a highway for fast charge collection and multiple scattering centers within the photoelectrode.

  20. Ordered assembly of NiCo₂O₄ multiple hierarchical structures for high-performance pseudocapacitors.

    Science.gov (United States)

    Zhou, Qingwen; Xing, Jiachao; Gao, Yanfang; Lv, Xiaojun; He, Yongmei; Guo, Zihan; Li, Yueming

    2014-07-23

    The design and development of nanomaterials has become central to the advancement of pseudocapacitive performance. Many one-dimensional nanostructures (1D NSs), two-dimensional nanostructures (2D NSs), and three-dimensional hierarchical structures (3D HSs) composed of these building blocks have been synthesized as pseudocapacitive materials via different methods. However, due to the unclear assembly mechanism of these NSs, reports of HSs simultaneously assembled from two or more types of NSs are rare. In this article, NiCo2O4 multiple hierarchical structures (MHSs) composed of 1D nanowires and 2D nanosheets are simply grown on Ni foam using an ordered two-step hydrothermal synthesis followed by annealing processing. The low-dimensional nanowire is found to hold priority in the growth order, rather than the high-dimensional nanosheet, thus effectively promoting the integration of these different NSs in the assembly of the NiCo2O4 MHSs. With vast electroactive surface area and favorable mesoporous architecture, the NiCo2O4 MHSs exhibit a high specific capacitance of up to 2623.3 F g(-1), scaled to the active mass of the NiCo2O4 sample at a current density of 1 A g(-1). A nearly constant rate performance of 68% is achieved at a current density ranging from 1 to 40 A g(-1), and the sample retains approximately 94% of its maximum capacitance even after 3000 continuous charge-discharge cycles at a consistently high current density of 10 A g(-1).

  1. Origin of Hierarchical Structures of Quark and Lepton Mass Matrices

    CERN Document Server

    Koide, Yoshio

    2015-01-01

    It is shown that the so-called "Yukawaon" model can give a unified description of masses, mixing and $CP$ violation parameters of quarks and leptons without using any hierarchical (family number-dependent) parameters besides the charged lepton masses. Here, we have introduced a phase matrix $P={\\rm daig}(e^{i \\phi_1}, e^{i \\phi_2}, e^{i \\phi_3})$ with the phase parameters $(\\phi_1, \\phi_2, \\phi_3)$ which are described in terms of family number-independent parameters, together with using only the charged lepton mass parameters as the family number-dependent parameters. In this paper, the $CP$ violating phase parameters $\\delta_{CP}^q$ and $\\delta_{CP}^\\ell$ in the standard expression of $V_{CKM}$ and $U_{PMNS}$ are predicted as $\\delta_{CP}^q \\simeq 72^\\circ$ and $\\delta_{CP}^\\ell \\simeq -76^\\circ$, respectively, i.e. $\\delta_{CP}^\\ell \\sim - \\delta_{CP}^q$.

  2. Children's Knowledge of Hierarchical Phrase Structure: Quantifier Floating in Japanese

    Science.gov (United States)

    Suzuki, Takaaki; Yoshinaga, Naoko

    2013-01-01

    The interpretation of floating quantifiers in Japanese requires knowledge of hierarchical phrase structure. However, the input to children is insufficient or even misleading, as our analysis indicates. This presents an intriguing question on learnability: do children interpret floating quantifiers based on a structure-dependent rule which is not…

  3. A Hierarchical Linear Model with Factor Analysis Structure at Level 2

    Science.gov (United States)

    Miyazaki, Yasuo; Frank, Kenneth A.

    2006-01-01

    In this article the authors develop a model that employs a factor analysis structure at Level 2 of a two-level hierarchical linear model (HLM). The model (HLM2F) imposes a structure on a deficient rank Level 2 covariance matrix [tau], and facilitates estimation of a relatively large [tau] matrix. Maximum likelihood estimators are derived via the…

  4. Hierarchical Structure, Disassortativity and Information Measures of the US Flight Network

    Institute of Scientific and Technical Information of China (English)

    WANG Ru; CAI Xu

    2005-01-01

    @@ We investigate the mixing structure of directed and evolutionary US flight network. It is shown that such a network is a hierarchical network, with average assortativity coefficient -0.37. Application of the informationbased method that can give the same result provides a way to explore the structure of complex networks.

  5. Asymmetric block copolymer membranes with ultrahigh porosity and hierarchical pore structure by plain solvent evaporation

    KAUST Repository

    Yu, H.

    2016-09-14

    Membranes with a hierarchical porous structure could be manufactured from a block copolymer blend by pure solvent evaporation. Uniform pores in a 30 nm thin skin layer supported by a macroporous structure were formed. This new process is attractive for membrane production because of its simplicity and the lack of liquid waste.

  6. Hierarchical structure graphitic-like/MoS2 film as superlubricity material

    Science.gov (United States)

    Gong, Zhenbin; Jia, Xiaolong; Ma, Wei; Zhang, Bin; Zhang, Junyan

    2017-08-01

    Friction and wear result in a great amount of energy loss and the invalidation of mechanical parts, thus it is necessary to minimize friction in practical application. In this study, the graphitic-like/MoS2 films with hierarchical structure were synthesized by the combination of pulse current plasma chemical-vapor deposition and medium frequency unbalanced magnetron sputtering in preheated environment. This hierarchical structure composite with multilayer nano sheets endows the films excellent tribological performance, which easily achieves macro superlubricity (friction coefficient ∼0.004) under humid air. Furthermore, it is expected that hierarchical structure of graphitic-like/MoS2 films could match the requirements of large scale, high bear-capacity and wear-resistance of actual working conditions, which could be widely used in the industrial production as a promising superlubricity material.

  7. Hierarchical structure for audio-video based semantic classification of sports video sequences

    Science.gov (United States)

    Kolekar, M. H.; Sengupta, S.

    2005-07-01

    A hierarchical structure for sports event classification based on audio and video content analysis is proposed in this paper. Compared to the event classifications in other games, those of cricket are very challenging and yet unexplored. We have successfully solved cricket video classification problem using a six level hierarchical structure. The first level performs event detection based on audio energy and Zero Crossing Rate (ZCR) of short-time audio signal. In the subsequent levels, we classify the events based on video features using a Hidden Markov Model implemented through Dynamic Programming (HMM-DP) using color or motion as a likelihood function. For some of the game-specific decisions, a rule-based classification is also performed. Our proposed hierarchical structure can easily be applied to any other sports. Our results are very promising and we have moved a step forward towards addressing semantic classification problems in general.

  8. Leading virtual teams: hierarchical leadership, structural supports, and shared team leadership.

    Science.gov (United States)

    Hoch, Julia E; Kozlowski, Steve W J

    2014-05-01

    Using a field sample of 101 virtual teams, this research empirically evaluates the impact of traditional hierarchical leadership, structural supports, and shared team leadership on team performance. Building on Bell and Kozlowski's (2002) work, we expected structural supports and shared team leadership to be more, and hierarchical leadership to be less, strongly related to team performance when teams were more virtual in nature. As predicted, results from moderation analyses indicated that the extent to which teams were more virtual attenuated relations between hierarchical leadership and team performance but strengthened relations for structural supports and team performance. However, shared team leadership was significantly related to team performance regardless of the degree of virtuality. Results are discussed in terms of needed research extensions for understanding leadership processes in virtual teams and practical implications for leading virtual teams.

  9. Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

    KAUST Repository

    Chen, Ping-Hei

    2011-01-01

    This study successfully develops a versatile method of producing superhydrophobic surfaces with micro/nano-silica hierarchical structures on glass surfaces. Optically transparent super hydrophobic silica thin films were prepared by spin-coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements. The glass substrates in this study were modified with different particles: micro-silica particles, nano-silica particles, and hierarchical structures. This study includes SEM micrographs of the modified glass surfaces with hierarchical structures at different magnifications. © 2011 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

  10. One-Step Fabrication of Hierarchically Structured Silicon Surfaces and Modification of Their Morphologies Using Sacrificial Layers

    Directory of Open Access Journals (Sweden)

    Seong J. Cho

    2013-01-01

    Full Text Available Fabrication of one-dimensional nanostructures is a key issue for optical devices, fluidic devices, and solar cells because of their unique functionalities such as antireflection and superhydrophobicity. Here, we report a novel one-step process to fabricate patternable hierarchical structures consisting of microstructures and one-dimensional nanostructures using a sacrificial layer. The layer plays a role as not only a micromask for producing microstructures but also as a nanomask for nanostructures according to the etching time. Using this method, we fabricated patterned hierarchical structures, with the ability to control the shape and density of the nanostructure. The various architectures provided unique functionalities. For example, our sacrificial-layer etching method allowed nanostructures denser than what would be attainable with conventional processes to form. The dense nanostructure resulted in a very low reflectance of the silicon surface (less than 1%. The nanostructured surface and hierarchically structured surface also exhibited excellent antiwetting properties, with a high contact angle (>165° and low sliding angle (<1°. We believe that our fabrication approach will provide new insight into functional surfaces, such as those used for antiwetting and antireflection surface applications.

  11. Construction of super-hydrophobic iron with a hierarchical surface structure

    Science.gov (United States)

    Yuan, Zhiqing; Bin, Jiping; Wang, Xian; Wang, Menglei; Peng, Chaoyi; Xing, Suli; Xiao, Jiayu; Zeng, Jingcheng; Xiao, Ximei; Fu, Xin

    2014-04-01

    Wettability of an iron surface is crucial for the wide applications of iron in practice. In this work, a hierarchical structure highly similar to that of the underside of a bamboo leaf was constructed on an iron surface via the template method and controllable etching. After modification by stearic acid, the iron surface with hierarchical structure showed excellent water repellency, with an average contact angle of 156° and a sliding angle of 3°. X-ray diffraction (XRD) techniques and Fourier transform infrared spectroscopy (FTIR) are applied to examine the chemical components of an iron surface.

  12. Multi-scaling hierarchical structure analysis on the sequence of E. coli complete genome

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We have applied the newly developed hierarchical structure theory for complex systems to analyze the multi-scaling structures of the nucleotide density distribution along a linear DNA sequence from the complete Escherichia coli genome. The hierarchical symmetry in the nucleotide density distribution was demonstrated. In particular, we have shown that the G, C density distribution that represents a strong H-bonding between the two DNA chains is more coherent with smaller similarity parameter compared to that of A, T density distribution, indicating a better organized multi-scaling fluctuation field for G, C density distribution along the genome sequence. The biological significance of these findings is under investigation.

  13. Fabrication of hierarchical structures for stable superhydrophobicity on metallic planar and cylindrical inner surfaces

    Science.gov (United States)

    Hao, Xiuqing; Wang, Li; Lv, Danhui; Wang, Quandai; Li, Liang; He, Ning; Lu, Bingheng

    2015-01-01

    Recently, the construction of stable superhydrophobicity on metallic wetting surfaces has gained increasing attention due to its potential wide applications. In this paper, we propose an economic fabricating method, which not only is suitable for metallic planar surfaces, but also could be applied onto cylindrical inner surfaces. It mainly involves two steps: etching micro-concaves by a movable mask electrochemical micromachining (EMM) technique and fabricating nanopillars of ZnO by a hydrothermal method. Then the influences of surface morphology on the static and dynamic behaviors of water droplets are investigated. The energy loss during impact on the surfaces is quantified in terms of the restitution coefficient for droplets bouncing off the surfaces. For hierarchical structures with excellent superhydrophobicity (contact angle ≈180° and sliding angle ≤1°), the droplet bounces off the surface several times, superior to the droplet's response on single nanopillars (contact angle ≈165.8° and sliding angle ≈6.29°) where droplet bounces off only for limited a number of times, and even far better than the dynamics of a liquid droplet impinging on microstructures (contact angle ≈132.1° and sliding angle >90°) where droplet does not rebound and remains pinned. The highest elasticity is obtained on the hierarchical surface, where the restitution coefficient can be as large as 0.94. The fabricating method is then applied onto the cylindrical inner surface and the wetting behavior is confirmed to be consistent with the planar surface. This method, which can be generalized to any kind of solid electroconductive metal or other surfaces with different shapes, could find wide practical applications in self-cleaning surfaces, chemical industry, microfluidic devices, mechanical engineering and aviation.

  14. A spatial analysis of hierarchical waste transport structures under growing demand.

    Science.gov (United States)

    Tanguy, Audrey; Glaus, Mathias; Laforest, Valérie; Villot, Jonathan; Hausler, Robert

    2016-10-01

    The design of waste management systems rarely accounts for the spatio-temporal evolution of the demand. However, recent studies suggest that this evolution affects the planning of waste management activities like the choice and location of treatment facilities. As a result, the transport structure could also be affected by these changes. The objective of this paper is to study the influence of the spatio-temporal evolution of the demand on the strategic planning of a waste transport structure. More particularly this study aims at evaluating the effect of varying spatial parameters on the economic performance of hierarchical structures (with one transfer station). To this end, three consecutive generations of three different spatial distributions were tested for hierarchical and non-hierarchical transport structures based on costs minimization. Results showed that a hierarchical structure is economically viable for large and clustered spatial distributions. The distance parameter was decisive but the loading ratio of trucks and the formation of clusters of sources also impacted the attractiveness of the transfer station. Thus the territories' morphology should influence strategies as regards to the installation of transfer stations. The use of spatial-explicit tools such as the transport model presented in this work that take into account the territory's evolution are needed to help waste managers in the strategic planning of waste transport structures.

  15. Controlled Fabrication of Flower-like Nickel Oxide Hierarchical Structures and Their Application in Water Treatment

    Directory of Open Access Journals (Sweden)

    Linxia Wang

    2012-01-01

    Full Text Available Flower-like NiO hierarchical structures with 2–5 μm diameter assembled from nanosheet building blocks have been successfully fabricated via a wet-chemical method combined with thermodecomposition technology. The template-free method is facile and effective in preparing flower-like NiO superstructures in high yield. The intermediate product and final hierarchical structures are characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray diffraction (XRD, Fourier transform IR (FTIR, and thermogravimetric analysis (TGA. The effects of growth temperature and reaction time on the morphologies of the as-prepared structures were investigated by SEM characterization and a possible mechanism for the formation of flower-like NiO is proposed. Based on the nitrogen adsorption and desorption measurements, the BET surface area of the as-obtained sample is 55.7 m2/g and the pore-size distribution plot indicates a bimodal mesopore distribution, with pore sizes of ca. 2.6 nm and 7.4 nm, respectively. In comparison with sphere-like and rod-like structures, the flower-like NiO hierarchical structures show an excellent ability to rapidly remove various pollutants when used as adsorbent and photocatalyst in waste-water treatment, which may be attributed to its unique hierarchical and porous surface structures.

  16. Joint Hierarchical Category Structure Learning and Large-Scale Image Classification

    Science.gov (United States)

    Qu, Yanyun; Lin, Li; Shen, Fumin; Lu, Chang; Wu, Yang; Xie, Yuan; Tao, Dacheng

    2017-09-01

    We investigate the scalable image classification problem with a large number of categories. Hierarchical visual data structures are helpful for improving the efficiency and performance of large-scale multi-class classification. We propose a novel image classification method based on learning hierarchical inter-class structures. Specifically, we first design a fast algorithm to compute the similarity metric between categories, based on which a visual tree is constructed by hierarchical spectral clustering. Using the learned visual tree, a test sample label is efficiently predicted by searching for the best path over the entire tree. The proposed method is extensively evaluated on the ILSVRC2010 and Caltech 256 benchmark datasets. Experimental results show that our method obtains significantly better category hierarchies than other state-of-the-art visual tree-based methods and, therefore, much more accurate classification.

  17. Topology of the correlation networks among major currencies using hierarchical structure methods

    Science.gov (United States)

    Keskin, Mustafa; Deviren, Bayram; Kocakaplan, Yusuf

    2011-02-01

    We studied the topology of correlation networks among 34 major currencies using the concept of a minimal spanning tree and hierarchical tree for the full years of 2007-2008 when major economic turbulence occurred. We used the USD (US Dollar) and the TL (Turkish Lira) as numeraires in which the USD was the major currency and the TL was the minor currency. We derived a hierarchical organization and constructed minimal spanning trees (MSTs) and hierarchical trees (HTs) for the full years of 2007, 2008 and for the 2007-2008 period. We performed a technique to associate a value of reliability to the links of MSTs and HTs by using bootstrap replicas of data. We also used the average linkage cluster analysis for obtaining the hierarchical trees in the case of the TL as the numeraire. These trees are useful tools for understanding and detecting the global structure, taxonomy and hierarchy in financial data. We illustrated how the minimal spanning trees and their related hierarchical trees developed over a period of time. From these trees we identified different clusters of currencies according to their proximity and economic ties. The clustered structure of the currencies and the key currency in each cluster were obtained and we found that the clusters matched nicely with the geographical regions of corresponding countries in the world such as Asia or Europe. As expected the key currencies were generally those showing major economic activity.

  18. Fabrication and condensation characteristics of metallic superhydrophobic surface with hierarchical micro-nano structures

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin

    2016-05-01

    Metallic superhydrophobic surfaces have various applications in aerospace, refrigeration and other engineering fields due to their excellent water repellent characteristics. This study considers a simple but widely applicable fabrication method using a two simultaneous chemical reactions method to prepare the acid-salt mixed solutions to process the metal surfaces with surface deposition and surface etching to construct hierarchical micro-nano structures on the surface and then modify the surface with low surface-energy materials. Al-based and Cu-based superhydrophobic surfaces were fabricated using this method. The Al-based superhydrophobic surface had a water contact angle of 164° with hierarchical micro-nano structures similar to the lotus leaves. The Cu-based surface had a water contact angle of 157° with moss-like hierarchical micro-nano structures. Droplet condensation experiments were also performed on these two superhydrophobic surfaces to investigate their condensation characteristics. The results show that the Al-based superhydrophobic surface has lower droplet density, higher droplet jumping probability, slower droplet growth rate and lower surface coverage due to the more structured hierarchical structures.

  19. Hierarchically structured polysulfone/titania fibrous membranes with enhanced air filtration performance.

    Science.gov (United States)

    Wan, Huigao; Wang, Na; Yang, Jianmao; Si, Yinsong; Chen, Kun; Ding, Bin; Sun, Gang; El-Newehy, Mohamed; Al-Deyab, Salem S; Yu, Jianyong

    2014-03-01

    Hierarchically structured, superhydrophobic filter medium exhibiting robust filtration performance to airborne particulate were prepared by a facile deposition of electrospun polysulfone/titania nanoparticles (PSU/TiO2 NPs) on a conventional nonwoven substrate. The air permeability, tensile strength and abrasion resistance of pristine PSU fibrous membranes could be finely controlled by regulating the solvent composition and number ratios of jets. By employing the TiO2 NPs incorporation, the pristine PSU fibers were endowed with promising superhydrophobicity with a water contact angle of up to 152°. The quantitative hierarchical roughness analysis using N2 adsorption method has confirmed the major contribution of TiO2 NPs on enhancing the porous structure and surface fractal features with irregular rough structure. Filtration performance studies have revealed that the filtration efficiency and pressure drop of resultant hybrid membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. Furthermore, the as-prepared PSU/TiO2-5 membrane exhibited improved filtration efficiency (99.997%) and pressure drop (45.3 Pa) compared with pristine PSU membrane, which would make them a promising media for fine particle filtration, and a new insight was also provided into the design and development of high performance filter medium based on hierarchical structured fibers.

  20. Hierarchically structured nanocarbon electrodes for flexible solid lithium batteries

    KAUST Repository

    Wei, Di

    2013-09-01

    The ever increasing demand for storage of electrical energy in portable electronic devices and electric vehicles is driving technological improvements in rechargeable batteries. Lithium (Li) batteries have many advantages over other rechargeable battery technologies, including high specific energy and energy density, operation over a wide range of temperatures (-40 to 70. °C) and a low self-discharge rate, which translates into a long shelf-life (~10 years) [1]. However, upon release of the first generation of rechargeable Li batteries, explosions related to the shorting of the circuit through Li dendrites bridging the anode and cathode were observed. As a result, Li metal batteries today are generally relegated to non-rechargeable primary battery applications, because the dendritic growth of Li is associated with the charging and discharging process. However, there still remain significant advantages in realizing rechargeable secondary batteries based on Li metal anodes because they possess superior electrical conductivity, higher specific energy and lower heat generation due to lower internal resistance. One of the most practical solutions is to use a solid polymer electrolyte to act as a physical barrier against dendrite growth. This may enable the use of Li metal once again in rechargeable secondary batteries [2]. Here we report a flexible and solid Li battery using a polymer electrolyte with a hierarchical and highly porous nanocarbon electrode comprising aligned multiwalled carbon nanotubes (CNTs) and carbon nanohorns (CNHs). Electrodes with high specific surface area are realized through the combination of CNHs with CNTs and provide a significant performance enhancement to the solid Li battery performance. © 2013 Elsevier Ltd.

  1. Hierarchical structures in cold-drawn pearlitic steel wire

    DEFF Research Database (Denmark)

    Zhang, Xiaodan; Godfrey, Andrew; Hansen, Niels

    2013-01-01

    in the structure and crystallography when a randomly oriented cementite structure in a patented wire during wire drawing is transformed into a lamellar structure parallel to the drawing axis. Changes in the interlamellar spacing and in the misorientation angle along and across the ferrite lamellae show significant...

  2. A hierarchical nanostructure consisting of amorphous MnO 2, Mn 3O 4 nanocrystallites, and single-crystalline MnOOH nanowires for supercapacitors

    Science.gov (United States)

    Hu, Chi-Chang; Hung, Ching-Yun; Chang, Kuo-Hsin; Yang, Yi-Lin

    In this communication, a porous hierarchical nanostructure consisting of amorphous MnO 2 (a-MnO 2), Mn 3O 4 nanocrystals, and single-crystalline MnOOH nanowires is designed for the supercapacitor application, which is prepared by a simple two-step electrochemical deposition process. Because of the gradual co-transformation of Mn 3O 4 nanocrystals and a-MnO 2 nanorods into an amorphous manganese oxide, the cycle stability of a-MnO 2 is obviously enhanced by adding Mn 3O 4. This unique ternary oxide nanocomposite with 100-cycle CV activation exhibits excellent capacitive performances, i.e., excellent reversibility, high specific capacitances (470 F g -1 in CaCl 2), high power property, and outstanding cycle stability. The highly porous microstructures of this composite before and after the 10,000-cycle CV test are examined by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  3. Hierarchical structural nanopore arrays fabricated by pre-patterning aluminum using nanosphere lithography.

    Science.gov (United States)

    Wang, Xinnan; Xu, Shuping; Cong, Ming; Li, Haibo; Gu, Yuejiao; Xu, Weiqing

    2012-04-10

    A highly ordered and hierarchical structural nanopore array is fabricated via anodizing a pre-patterned aluminum foil under an optimized voltage. A pre-patterned hexagonal nanoindentation array on an aluminum substrate is prepared via the nanosphere lithography method. This pattern leads to an elaborate nanochannel structure with seven nanopores in each nanoindentation after anodization treatment. The structure achieved in our study is new, interesting, and likely to be applied in photonic devices.

  4. Elaborately prepared hierarchical structure titanium dioxide for remarkable performance in lithium storage

    Science.gov (United States)

    Tian, Qinghua; Luo, Dong; Li, Xiaowei; Zhang, Zhengxi; Yang, Li; Hirano, Shin-ichi

    2016-05-01

    Titanium dioxide (TiO2) has been considered to be a promisingly alternative anode material for lithium-ion batteries and thus attracted wide research interest. But, its practical application in lithium-ion batteries is seriously impeded by low capacity and poor rate capability. In the present work, the electrochemical performance of TiO2 is significantly improved by elaborately fabricating hierarchical structures. These as-prepared four hierarchical structure TiO2 assembled by different building blocks (TO2-2 h, TO2-6 h, TO2-18 h and TO2-24 h) all exhibit impressed performance. More importantly, the TO2-6 h constructed by curved nanosheets exhibits the best performance, delivering a capacity of 231.6 mAh g-1 at 0.2C after 200 cycles, and capacities of 187.1 and 129.3 mAh g-1 at 1 and 10C after even 1200 cycles, respectively. The results indicated that design and fabrication of hierarchical structure is an effective strategy for significantly improving the electrochemical performance of TiO2 electrodes, and the electrochemical performance of hierarchical structure TiO2 is heavily dependent on its building blocks. It is suggested that thus excellent electrochemical performance may make TiO2-6 h a promising anode material for advanced lithium-ion batteries with high capacity, good rate capability and long life.

  5. Can Prosody Be Used to Discover Hierarchical Structure in Continuous Speech?

    Science.gov (United States)

    Langus, Alan; Marchetto, Erika; Bion, Ricardo Augusto Hoffmann; Nespor, Marina

    2012-01-01

    We tested whether adult listeners can simultaneously keep track of variations in pitch and syllable duration in order to segment continuous speech into phrases and group these phrases into sentences. The speech stream was constructed so that prosodic cues signaled hierarchical structures (i.e., phrases embedded within sentences) and non-adjacent…

  6. Symptom structure of PTSD: support for a hierarchical model separating core PTSD symptoms from dysphoria

    NARCIS (Netherlands)

    Rademaker, A.R.; Minnen, A. van; Ebberink, F.; Zuiden, M. van; Geuze, E.

    2012-01-01

    Background: As of yet, no collective agreement has been reached regarding the precise factor structure of posttraumatic stress disorder (PTSD). Several alternative factor-models have been proposed in the last decades. Objective: The current study examined the fit of a hierarchical adaptation of the

  7. A developmental model of hierarchical stage structure in objective moral judgements

    NARCIS (Netherlands)

    J. Boom; P.C.M. Molenaar

    1989-01-01

    A hierarchical structural model of moral judgment is proposed in which an S is characterized as occupying a particular moral stage. During development, the S's characteristic stage progresses along a latent, ordered dimension in an age-dependent way. Evaluation of prototypic statements representativ

  8. Task Switching in a Hierarchical Task Structure: Evidence for the Fragility of the Task Repetition Benefit

    Science.gov (United States)

    Lien, Mei-Ching; Ruthruff, Eric

    2004-01-01

    This study examined how task switching is affected by hierarchical task organization. Traditional task-switching studies, which use a constant temporal and spatial distance between each task element (defined as a stimulus requiring a response), promote a flat task structure. Using this approach, Experiment 1 revealed a large switch cost of 238 ms.…

  9. Hierarchical structures in cold-drawn pearlitic steel wire

    DEFF Research Database (Denmark)

    Zhang, Xiaodan; Godfrey, Andrew; Hansen, Niels

    2013-01-01

    The microstructure and crystallography of drawn pearlitic steel wires have been quantified by a number of electron microscopy techniques including scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction and nanobeam diffraction, with focus on the change......, and high-angle boundaries form in the A_BC structure parallel to the cementite lamellae. The structural and crystallographic analyses suggest that boundary strengthening and dislocation strengthening are important mechanisms in the cold-drawn wire. However, differences in structural parameters between...

  10. Identifying the hierarchical structure of customer complaint behaviors on the example of Iranian hotels

    Directory of Open Access Journals (Sweden)

    P. Charsetad

    2016-12-01

    Full Text Available The aim of this article. Consumer researchers have become increasingly interested in the study of coping. Despite the importance of coping strategies in service failure context, there isn’t any considerable research in Iran to identify coping behaviors. This article contributes to this novel paradigm by investigating structural theories of coping with service failure using a hierarchical structure. The purpose of present article was to identify and classify the coping strategies of Iranian people in the higher order and lower order factors in encountering to service failure. The results of the analysis. In this study nine dimensions, explaining the coping strategies with service failures, have been identified. The nine identified factors were labeled based on previous studies including; social support, avoidance, negative word of mouth, complain to service provider, third party complain, fatalism coping, self-controlling, emotional venting and denial coping. Reliability was evaluated on internal consistency by calculating Cronbach’s Alpha coefficient. The resulting coefficients were higher than 0,7 for all factors. After the extraction of lower order factors, Varimax rotation was used and was extracted three factors which were labeled as “active coping”, “expressive coping” and “denial / avoiding coping” based on literature review and previous research. The findings have allowed us to largely confirm the results obtained by previous studies, but using a sample of Iranian consumers. Specially, the factors found in this study were very similar to three dimensional model found in Duhachek and Tsarenko & Strizhakva. Therefore, can be concluded that there were several similarities between Iranian and other countries in coping behaviors. This fact contributed to the validation of this coping strategies framework showing its application to different contexts. So, a contribution of this study was to acknowledge this as an instrument to

  11. Mapping the hierarchical layout of the structural network of the macaque prefrontal cortex.

    Science.gov (United States)

    Goulas, Alexandros; Uylings, Harry B M; Stiers, Peter

    2014-05-01

    A consensus on the prefrontal cortex (PFC) holds that it is pivotal for flexible behavior and the integration of the cognitive, affective, and motivational domains. Certain models have been put forth and a dominant model postulates a hierarchical anterior-posterior gradient. The structural connectivity principles of this model dictate that increasingly anterior PFC regions exhibit more efferent connections toward posterior ones than vice versa. Such hierarchical asymmetry principles are thought to pertain to the macaque PFC. Additionally, the laminar patterns of the connectivity of PFC regions can be used for defining hierarchies. In the current study, we formally tested the asymmetry-based hierarchical principles of the anterior-posterior model by employing an exhaustive dataset on macaque PFC connectivity and tools from network science. On the one hand, the asymmetry-based principles and predictions of the hierarchical anterior-posterior model were not confirmed. The wiring of the macaque PFC does not fully correspond to the principles of the model, and its asymmetry-based hierarchical layout does not follow a strict anterior-posterior gradient. On the other hand, our results suggest that the laminar-based hierarchy seems a more tenable working hypothesis for models advocating an anterior-posterior gradient. Our results can inform models of the human PFC.

  12. Proton Conduction in Sulfonated Organic-Inorganic Hybrid Monoliths with Hierarchical Pore Structure.

    Science.gov (United States)

    von der Lehr, Martin; Seidler, Christopher F; Taffa, Dereje H; Wark, Michael; Smarsly, Bernd M; Marschall, Roland

    2016-09-28

    Porous organic-inorganic hybrid monoliths with hierarchical porosity exhibiting macro- and mesopores are prepared via sol-gel process under variation of the mesopore size. Organic moieties in the pore walls are incorporated by substituting up to 10% of the silicon precursor tetramethylorthosilicate with bisilylated benzene molecules. After functionalization with sulfonic acid groups, the resulting sulfonated hybrid monoliths featuring a bimodal pore structure are investigated regarding proton conduction depending on temperature and relative humidity. The hierarchical pore system and controlled mesopore design turn out to be crucial for sulfonation and proton conduction. These sulfonated hybrid hierarchical monoliths containing only 10% organic precursor exhibit higher proton conduction at different relative humidities than sulfonated periodic mesoporous organosilica made of 100% bisilylated precursors exhibiting solely mesopores, even with a lower concentration of sulfonic acid groups.

  13. Hierarchical cluster-tendency analysis of the group structure in the foreign exchange market

    Science.gov (United States)

    Wu, Xin-Ye; Zheng, Zhi-Gang

    2013-08-01

    A hierarchical cluster-tendency (HCT) method in analyzing the group structure of networks of the global foreign exchange (FX) market is proposed by combining the advantages of both the minimal spanning tree (MST) and the hierarchical tree (HT). Fifty currencies of the top 50 World GDP in 2010 according to World Bank's database are chosen as the underlying system. By using the HCT method, all nodes in the FX market network can be "colored" and distinguished. We reveal that the FX networks can be divided into two groups, i.e., the Asia-Pacific group and the Pan-European group. The results given by the hierarchical cluster-tendency method agree well with the formerly observed geographical aggregation behavior in the FX market. Moreover, an oil-resource aggregation phenomenon is discovered by using our method. We find that gold could be a better numeraire for the weekly-frequency FX data.

  14. INFOGRAPHIC MODELING OF THE HIERARCHICAL STRUCTURE OF THE MANAGEMENT SYSTEM EXPOSED TO AN INNOVATIVE CONFLICT

    Directory of Open Access Journals (Sweden)

    Chulkov Vitaliy Olegovich

    2012-12-01

    Full Text Available This article deals with the infographic modeling of hierarchical management systems exposed to innovative conflicts. The authors analyze the facts that serve as conflict drivers in the construction management environment. The reasons for innovative conflicts include changes in hierarchical structures of management systems, adjustment of workers to new management conditions, changes in the ideology, etc. Conflicts under consideration may involve contradictions between requests placed by customers and the legislation, any risks that may originate from the above contradiction, conflicts arising from any failure to comply with any accepted standards of conduct, etc. One of the main objectives of the theory of hierarchical structures is to develop a model capable of projecting potential innovative conflicts. Models described in the paper reflect dynamic changes in patterns of external impacts within the conflict area. The simplest model element is a monad, or an indivisible set of characteristics of participants at the pre-set level. Interaction between two monads forms a diad. Modeling of situations that involve a different number of monads, diads, resources and impacts can improve methods used to control and manage hierarchical structures in the construction industry. However, in the absence of any mathematical models employed to simulate conflict-related events, processes and situations, any research into, projection and management of interpersonal and group-to-group conflicts are to be performed in the legal environment

  15. Optical and photocatalytic properties of Mn doped flower-like ZnO hierarchical structures

    Science.gov (United States)

    Ma, Qun; Lv, Xiangzhou; Wang, Yongqian; Chen, Jieyu

    2016-10-01

    A novel Mn doped flower-like ZnO hierarchical structures were successfully synthesized with a facile ion-exchange method. Structural properties of the synthesized photocatalysis have been investigated with XRD, FESEM equipped with energy dispersive spectroscopy, while UV-vis and PL spectroscopy were employed to study their optical properties. The inner structure of doped ZnO hierarchical structure can be finely transformed from nanosheets to nanorods and to nanoparticles with the increasing of doping contents. All the synthesized Mn/ZnO samples exhibit strong blue-violet emission. Furthermore, the optical absorption towards visible light of ZnO was significantly enhanced due to the incorporation of Mn ions. The photocatalytic results indicate that photocatalytic activity of ZnO was enhanced with the doping of Mn and there is an optimum Mn doping level, leading to the highest photocatalytic performance.

  16. Learning Hierarchical and Topographic Dictionaries with Structured Sparsity

    CERN Document Server

    Mairal, Julien; Obozinski, Guillaume; Bach, Francis; 10.1117/12.893811

    2011-01-01

    Recent work in signal processing and statistics have focused on defining new regularization functions, which not only induce sparsity of the solution, but also take into account the structure of the problem. We present in this paper a class of convex penalties introduced in the machine learning community, which take the form of a sum of l_2 and l_infinity-norms over groups of variables. They extend the classical group-sparsity regularization in the sense that the groups possibly overlap, allowing more flexibility in the group design. We review efficient optimization methods to deal with the corresponding inverse problems, and their application to the problem of learning dictionaries of natural image patches: On the one hand, dictionary learning has indeed proven effective for various signal processing tasks. On the other hand, structured sparsity provides a natural framework for modeling dependencies between dictionary elements. We thus consider a structured sparse regularization to learn dictionaries embedde...

  17. Hierarchically structured titania films for application in photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Niedermeier, M.A.; Kaune, G.; Mueller-Buschbaum, P. [TU Muenchen, Garching (Germany). Lehrstuhl fuer Funktionelle Materialien; Perlich, J. [TU Muenchen, Garching (Germany). Lehrstuhl fuer Funktionelle Materialien; DESY, Hamburg (Germany). HASYLAB; Memesa, M. [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany); Gutmann, J.S. [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany); Mainz Univ. (Germany). Inst. fuer Physikalische Chemie

    2010-07-01

    The fabrication of nanostructured titania films is investigated. The nanostructures are prepared using the diblock copolymer polystyrene-block-polyethyleneoxide (P(S-b-EO)) as a structure directing agent. Using repetitive sol-gel chemistry together with spin coating a thin polymer-nanocomposite film is deposited on silicon substrates which is calcined in air to obtain crystalline titania nanostructures. Furthermore, different types of morphologies are combined. The thus obtained structures are investigated regarding their morphologies, for example using imaging techniques like SEM. Additionally, information about the crystallinity is obtained with XRD. From our results we discuss the use of our films for photovoltaic applications. (orig.)

  18. Kendall’s tau and agglomerative clustering for structure determination of hierarchical Archimedean copulas

    Directory of Open Access Journals (Sweden)

    Górecki J.

    2017-01-01

    Full Text Available Several successful approaches to structure determination of hierarchical Archimedean copulas (HACs proposed in the literature rely on agglomerative clustering and Kendall’s correlation coefficient. However, there has not been presented any theoretical proof justifying such approaches. This work fills this gap and introduces a theorem showing that, given the matrix of the pairwise Kendall correlation coefficients corresponding to a HAC, its structure can be recovered by an agglomerative clustering technique.

  19. An XML-hierarchical data structure for ENSDF

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, Aaron M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-03-15

    A data structure based on an eXtensible Markup Language (XML) hierarchy according to experimental nuclear structure data in the Evaluated Nuclear Structure Data File (ENSDF) is presented. A Python-coded translator has been developed to interpret the standard one-card records of the ENSDF datasets, together with their associated quantities defined according to field position, and generate corresponding representative XML output. The quantities belonging to this mixed-record format are described in the ENSDF manual. Of the 16 ENSDF records in total, XML output has been successfully generated for 15 records. An XML-translation for the Comment Record is yet to be implemented; this will be considered in a separate phase of the overall translation effort. Continuation records, not yet implemented, will also be treated in a future phase of this work. Several examples are presented in this document to illustrate the XML schema and methods for handling the various ENSDF data types. However, the proposed nomenclature for the XML elements and attributes need not necessarily be considered as a fixed set of constructs. Indeed, better conventions may be suggested and a consensus can be achieved amongst the various groups of people interested in this project. The main purpose here is to present an initial phase of the translation effort to demonstrate the feasibility of interpreting ENSDF datasets and creating a representative XML-structured hierarchy for data storage.

  20. Hierarchical structure formation in supramolecular comb-shaped block copolymers

    NARCIS (Netherlands)

    Hofman, Anton; ten Brinke, Gerrit; Loos, Katja

    2016-01-01

    Block copolymers are known to spontaneously form ordered structures at the nano-to mesoscale. Although the number of different morphologies is rather limited in diblock copolymer systems, their phase behavior becomes increasingly more complex with each additional building block. Synthesis of such al

  1. Synthesis and structural characterization of two-dimensional hierarchical covellite nano-structures

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Nirupam, E-mail: n.banerjee@utwente.nl [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); MESA Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Krupanidhi, S.B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

    2012-12-14

    We report a simple, template free and low-temperature hydrothermal reaction pathway using Cu(II) - thiourea complex (prepared in situ from copper (II) chloride and thiourea as precursors) and citric acid as complexing agent to synthesize two-dimensional hierarchical nano-structures of covellite (CuS). The product was characterized with the help of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy (XPS). The concentration of citric acid in the hydrothermal precursor solution was seen to have a profound effect on the nanostructure of the product generated. Based on the outcoming product nano-architecture at different concentration of the ionic surfactant in the hydrothermal precursor solution a possible mechanism suited for reaction and further nucleation is also discussed. -- Highlights: Black-Right-Pointing-Pointer A novel reaction scheme is proposed for synthesizing covellite 2D nano-structures. Black-Right-Pointing-Pointer The nanostructures were thoroughly characterized, both structurally and chemically. Black-Right-Pointing-Pointer Through variation of synthetic parameters a general growth mechanism is proposed.

  2. Facile synthesis of Zn doped CuO hierarchical nanostructures: Structural, optical and antibacterial properties

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Javed, E-mail: tariqjan84@gmail.com, E-mail: javed.suggau@iiu.edu.pk; Jan, Tariq, E-mail: tariqjan84@gmail.com, E-mail: javed.suggau@iiu.edu.pk; Ul-Hassan, Sibt; Umair Ali, M.; Abbas, Fazal [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University, H-10, Islamabad (Pakistan); Ahmed, Ishaq [Experimental Physics Labs, National Center for Physics, Islamabad (Pakistan); Mansoor, Qaisar; Ismail, Muhammad [Institute of Biomedical and Genetic Engineering (IBGE), Islamabad (Pakistan)

    2015-12-15

    Zn{sub x}Cu{sub 1−x}O (where x= 0, 0.01, 0.03, 0.05, 0.07 and 0.1 mol%) hierarchical nanostructures have been prepared via soft chemical route. X-ray diffraction (XRD) results of the synthesized samples reveal the monoclinic structure of CuO without any impurity related phases. The micro-structural parameters such as crystallite size and microstrain have been strongly influenced by Zn doping. Scanning electron microscope (SEM) analyses depict the formation of hierarchical nanostructures having average particle size in the range of 26-43 nm. The surface area of CuO nanostructures has been reduced systematically with the increase in Zn content which is linked with the variations in particle size. An obvious decrease in the optical band gap energy of the synthesized CuO hierarchical nanostructures has been observed with Zn doping which is assigned to the formation of shallow levels in the band gap of CuO and combined transition from oxygen 2p states to d sates of Cu and Zn ions. The bactericidal potency of the CuO hierarchical nanostructures have been found to be enhanced remarkably with Zn doping.

  3. Modular networks with hierarchical organization: The dynamical implications of complex structure

    Indian Academy of Sciences (India)

    Raj Kumar Pan; Sitabhra Sinha

    2008-08-01

    Several networks occurring in real life have modular structures that are arranged in a hierarchical fashion. In this paper, we have proposed a model for such networks, using a stochastic generation method. Using this model we show that, the scaling relation between the clustering and degree of the nodes is not a necessary property of hierarchical modular networks, as had previously been suggested on the basis of a deterministically constructed model. We also look at dynamics on such networks, in particular, the stability of equilibria of network dynamics and of synchronized activity in the network. For both of these, we find that, increasing modularity or the number of hierarchical levels tends to increase the probability of instability. As both hierarchy and modularity are seen in natural systems, which necessarily have to be robust against environmental fluctuations, we conclude that additional constraints are necessary for the emergence of hierarchical structure, similar to the occurrence of modularity through multi-constraint optimization as shown by us previously.

  4. Dielectric study on hierarchical water structures restricted in cement and wood materials

    Science.gov (United States)

    Abe, Fumiya; Nishi, Akihiro; Saito, Hironobu; Asano, Megumi; Watanabe, Seiei; Kita, Rio; Shinyashiki, Naoki; Yagihara, Shin; Fukuzaki, Minoru; Sudo, Seiichi; Suzuki, Youki

    2017-04-01

    Dielectric relaxation processes for mortar observed by broadband dielectric spectroscopy were analyzed in the drying and hydration processes for an aging sample in the frequency region from 1 MHz up to 2 MHz. At least two processes for structured water in the kHz frequency region and another mHz relaxation process affected by ionic behaviors were observed. Comparison of the relaxation parameters obtained for the drying and hydration processes suggests an existence of hierarchical water structures in the exchange of water molecules, which are originally exchanged from free water observed at around 20 GHz. The water molecules reflected in the lower frequency process of the two kHz relaxation processes are more restricted and take more homogeneous structures than the higher kHz relaxation process. These structured water usually hidden in large ionic behaviors for wood samples was observed by electrodes covered by a thin Teflon film, and hierarchical water structures were also suggested for wood samples. Dielectric spectroscopy technique is an effective tool to analyze the new concept of hierarchical water structures in complex materials.

  5. Hierarchical Structures from Inorganic Nanocrystal Self-Assembly for Photoenergy Utilization

    Directory of Open Access Journals (Sweden)

    Yun-Pei Zhu

    2014-01-01

    Full Text Available Self-assembly has emerged as a powerful strategy for controlling the structure and physicochemical properties of ensembles of inorganic nanocrystals. Hierarchical structures from nanocrystal assembly show collective properties that differ from individual nanocrystals and bulk samples. Incorporation of structural hierarchy into nanostructures is of great importance as a result of enhancing mass transportation, reducing resistance to diffusion, and high surface areas for adsorption and reaction, and thus much effort has been devoted to the exploration of various novel organizing schemes through which inorganic porous structure with architectural design can be created. In this paper, the recent research progress in this field is reviewed. The general strategies for the synthesis of hierarchical structures assembled from nanobuilding blocks are elaborated. The well-defined hierarchical structures provide new opportunities for optimizing, tuning, and/or enhancing the properties and performance of these materials and have found applications in photoenergy utilization including photodegradation, photocatalytic H2 production, photocatalytic CO2 conversion, and sensitized solar cells, and these are discussed illustratively.

  6. Prediction of Halocarbon Toxicity from Structure: A Hierarchical QSAR Approach

    Energy Technology Data Exchange (ETDEWEB)

    Gute, B D; Balasubramanian, K; Geiss, K; Basak, S C

    2003-04-11

    Mathematical structural invariants and quantum theoretical descriptors have been used extensively in quantitative structure-activity relationships (QSARs) for the estimation of pharmaceutical activities, biological properties, physicochemical properties, and the toxicities of chemicals. Recently our research team has explored the relative importance of various levels of chemodescriptors, i.e., topostructural, topochemical, geometrical, and quantum theoretical descriptors, in property estimation. This study examines the contribution of chemodescriptors ranging from topostructural to quantum theoretic calculations up to the Gaussian STO-3G level in the prediction of the toxicity of a set of twenty halocarbons. We also report the results of experimental cell-level toxicity studies on these twenty halocarbons to validate our models.

  7. Hierarchical Sets: Analyzing Pangenome Structure through Scalable Set Visualizations

    OpenAIRE

    Pedersen, Thomas Lin

    2017-01-01

    The increase in available microbial genome sequences has resulted in an increase in the size of the pangenomes being analyzed. Current pangenome visualizations are not intended for the pangenome sizes possible today and new approaches are necessary in order to convert the increase in available information to increase in knowledge. As the pangenome data structure is essentially a collection of sets we explore the potential for scalable set visualization as a tool for pangenome analysis. We pre...

  8. Fractal analysis of the hierarchic structure of fossil coal surface

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A.D.; Vasilenko, T.A.; Kirillov, A.K. [National Academy of Sciences, Donetsk (Ukraine)

    2008-05-15

    The fractal analysis is described as method of studying images of surface of fossil coal, one of the natural sorbent, with the aim of determining its structural surface heterogeneity. The deformation effect as a reduction in the dimensions of heterogeneity boundaries is considered. It is shown that the theory of nonequilibrium dynamic systems permits to assess a formation level of heterogeneities involved into a sorbent composition by means of the Hurst factor.

  9. Mechanical Properties of Zirconium Ceramics with Hierarchical Porous Structure

    Science.gov (United States)

    Kulkov, S.; Shutilova, E.; Buyakova, S.

    2016-07-01

    The work studies porous ceramics produced from ultra-fine powders. The porosity of ceramic samples was from 15 to 80%. The ceramic materials had cellular structure. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations, which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformations on deformation diagrams is due to mechanical instability of cellular elements in a ceramic frame.

  10. Structure-function relationships in Macadamia integrifolia seed coats--fundamentals of the hierarchical microstructure.

    Directory of Open Access Journals (Sweden)

    Paul Schüler

    Full Text Available The shells/coats of nuts and seeds are often very hard to crack. This is particularly the case with Macadamia seed coats, known to exhibit astoundingly high strength and toughness. We performed an extensive materials science characterization of the complex hierarchical structure of these coats, using light and scanning electron microscopy in 2D as well as microCT for 3D characterization. We differentiate nine hierarchical levels that characterize the structure ranging from the whole fruit on the macroscopic scale down to the molecular scale. From a biological viewpoint, understanding the hierarchical structure may elucidate why it is advantageous for these seed coats to be so difficult to break. From an engineering viewpoint, microstructure characterization is important for identifying features that contribute to the high strength and cracking resistance of these objects. This is essential for revealing the underlying structure-function-relationships. Such information will help us develop engineering materials and lightweight-structures with improved fracture and puncture resistance.

  11. Hierarchical photonic structured stimuli-responsive materials as high-performance colorimetric sensors.

    Science.gov (United States)

    Lu, Tao; Zhu, Shenmin; Chen, Zhixin; Wang, Wanlin; Zhang, Wang; Zhang, Di

    2016-05-21

    Hierarchical photonic structures in nature are of special interest because they can be used as templates for fabrication of stimuli-responsive photonic crystals (PCs) with unique structures beyond man-made synthesis. The current stimuli-responsive PCs templated directly from natural PCs showed a very weak external stimuli response and poor durability due to the limitations of natural templates. Herein, we tackle this problem by chemically coating functional polymers, polyacrylamide, on butterfly wing scales which have hierarchical photonic structures. As a result of the combination of the strong water absorption properties of the polyacrylamide and the PC structures of the butterfly wing scales, the designed materials demonstrated excellent humidity responsive properties and a tremendous colour change. The colour change is induced by the refractive index change which is in turn due to the swollen nature of the polymer when the relative humidity changes. The butterfly wing scales also showed an excellent durability which is due to the chemical bonds formed between the polymer and wing scales. The synthesis strategy provides an avenue for the promising applications of stimuli-responsive PCs with hierarchical structures.

  12. Superhydrophobic hierarchically structured surfaces in biology: evolution, structural principles and biomimetic applications

    Science.gov (United States)

    Mail, M.; Neinhuis, C.

    2016-01-01

    A comprehensive survey of the construction principles and occurrences of superhydrophobic surfaces in plants, animals and other organisms is provided and is based on our own scanning electron microscopic examinations of almost 20 000 different species and the existing literature. Properties such as self-cleaning (lotus effect), fluid drag reduction (Salvinia effect) and the introduction of new functions (air layers as sensory systems) are described and biomimetic applications are discussed: self-cleaning is established, drag reduction becomes increasingly important, and novel air-retaining grid technology is introduced. Surprisingly, no evidence for lasting superhydrophobicity in non-biological surfaces exists (except technical materials). Phylogenetic trees indicate that superhydrophobicity evolved as a consequence of the conquest of land about 450 million years ago and may be a key innovation in the evolution of terrestrial life. The approximate 10 million extant species exhibit a stunning diversity of materials and structures, many of which are formed by self-assembly, and are solely based on a limited number of molecules. A short historical survey shows that bionics (today often called biomimetics) dates back more than 100 years. Statistical data illustrate that the interest in biomimetic surfaces is much younger still. Superhydrophobicity caught the attention of scientists only after the extreme superhydrophobicity of lotus leaves was published in 1997. Regrettably, parabionic products play an increasing role in marketing. This article is part of the themed issue ‘Bioinspired hierarchically structured surfaces for green science’. PMID:27354736

  13. Superhydrophobic hierarchically structured surfaces in biology: evolution, structural principles and biomimetic applications.

    Science.gov (United States)

    Barthlott, W; Mail, M; Neinhuis, C

    2016-08-06

    A comprehensive survey of the construction principles and occurrences of superhydrophobic surfaces in plants, animals and other organisms is provided and is based on our own scanning electron microscopic examinations of almost 20 000 different species and the existing literature. Properties such as self-cleaning (lotus effect), fluid drag reduction (Salvinia effect) and the introduction of new functions (air layers as sensory systems) are described and biomimetic applications are discussed: self-cleaning is established, drag reduction becomes increasingly important, and novel air-retaining grid technology is introduced. Surprisingly, no evidence for lasting superhydrophobicity in non-biological surfaces exists (except technical materials). Phylogenetic trees indicate that superhydrophobicity evolved as a consequence of the conquest of land about 450 million years ago and may be a key innovation in the evolution of terrestrial life. The approximate 10 million extant species exhibit a stunning diversity of materials and structures, many of which are formed by self-assembly, and are solely based on a limited number of molecules. A short historical survey shows that bionics (today often called biomimetics) dates back more than 100 years. Statistical data illustrate that the interest in biomimetic surfaces is much younger still. Superhydrophobicity caught the attention of scientists only after the extreme superhydrophobicity of lotus leaves was published in 1997. Regrettably, parabionic products play an increasing role in marketing.This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'. © 2016 The Author(s).

  14. Ultrahigh stress and strain in hierarchically structured hollow nanoparticles

    Science.gov (United States)

    Shan, Z. W.; Adesso, G.; Cabot, A.; Sherburne, M. P.; Syed Asif, S. A.; Warren, O. L.; Chrzan, D. C.; Minor, A. M.; Alivisatos, A. P.

    2008-12-01

    Nanocrystalline materials offer very high strength but are typically limited in their strain to failure, and efforts to improve deformability in these materials are usually found to be at the expense of strength. Using a combination of quantitative in situ compression in a transmission electron microscope and finite-element analysis, we show that the mechanical properties of nanoparticles can be directly measured and interpreted on an individual basis. We find that nanocrystalline CdS synthesized into a spherical shell geometry is capable of withstanding extreme stresses (approaching the ideal shear strength of CdS). This unusual strength enables the spherical shells to exhibit considerable deformation to failure (up to 20% of the sphere's diameter). By taking into account the structural hierarchy intrinsic to novel nanocrystalline materials such as this, we show it is possible to achieve and characterize the ultrahigh stresses and strains that exist within a single nanoparticle during deformation.

  15. A Generic Identification Scheme for Hierarchically Structured Objects

    Institute of Scientific and Technical Information of China (English)

    ChristianArnault; StanBentvelsen; 等

    2001-01-01

    The detector description database,the event data structure,the condition database are all examples(among others)of complex collections of objects which need to be unambiguously identified,not only internally to their own management structure.but also from one collection to the other.The requirements for such an identification scheme include the management of identifiers individually attached to each collected object,the possibility to formally spectify these identifiers (eg through dictionaries),to generate optimised and compact representations for these identifiers and to be able to use them as sorting and searching keys.we present here the generic toolkit developed in the context of the Atlas experiment to primarily provide the identification of the readout elements of the detector.This toolkit offers several either generic or specialized component such as:an XML based dictionary with which the formal specification of a particular object collection is expressed,a set of various binary representations for identifier objects(offering various level of compaction),range operators meant to manipulate ranges of identifiers,and finally a collection manager similar to the STL map but optimised for an organization keyed by Identifiers.All these components easily interoperate.In Particular the Identifier didctionary offers means of specifying permitted cardinalities of objects at each level of the hierarchy,This can then be translated into Identifier Ranges or can be used as the strategy driver for high compactification of the identifiers(e.g.to store very large number of identified objects).Current use of this toolkit within the detector description will be presented,and expected or possible other usages will be discussed.

  16. Synthesis of hierarchical NiO microsphere with waxberry-like structure and its enhanced lithium storage performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qi; Xu, Yue-Feng; Xu, Gui-Liang [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen, 361005 (China); Su, Hang [College of Energy, Xiamen University, Xiamen 361005 (China); Shen, Shou-Yu; Tu, Ting-Ting [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen, 361005 (China); Huang, Ling, E-mail: huangl@xmu.edu.cn [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen, 361005 (China); Li, Jun-Tao [College of Energy, Xiamen University, Xiamen 361005 (China); Sun, Shi-Gang [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen, 361005 (China); College of Energy, Xiamen University, Xiamen 361005 (China)

    2015-11-05

    This work reports a facile synthesis of hierarchical NiO microspheres with a waxberry-like structure by one-pot hydrothermal reaction followed by thermal annealing. We detected the composition of precursor by using two-dimensional detector X-ray diffractometer (XRD{sup 2}). In addition, XRD, TG, SEM, TEM and BET measurement were used to characterize the structural properties of the as-prepared materials. The XRD result showed that the precursor has been completely transformed into NiO materials by calcination at 300 °C (denoted as NiO-300). Moreover, thanks to the well conservation of hierarchical structure consisting of needle-like nanoparticles in NiO-300 sample, the charge capacity can be stabilized at 597.8 mAh g{sup −1} reversibly when cycled 100 times at a relatively high current density of 0.7C which show a very competitive capacity compared with other nano-structure NiO materials and commercial NiO material. It also showed high rate capability, the reversible charge capacity is still retained to 370.3 mAh g{sup −1}, even for the condition of 4.46C (high rate). This NiO-300 material's superior electrochemical performance should be exclusively attributed to the well conserved hierarchical waxberry-like structures, which shortens the diffusion pathways of lithium ions and electrons transfer as well as accommodate the drastic volume change during electrochemical charge/discharge process. - Highlights: • Hierarchical waxberry-like NiO has been synthesized by hydrothermal reaction. • Two-dimensional XRD (XRD{sup 2}) was used to ensure the composition of precursor. • The NiO-300 delivers a charge capacity of 597.8 mAh g{sup −1} cycled 100 weeks at 0.7C. • The superior electrochemical performance should be owed to waxberry-like structure.

  17. Hierarchical structure of the Sicilian goats revealed by Bayesian analyses of microsatellite information.

    Science.gov (United States)

    Siwek, M; Finocchiaro, R; Curik, I; Portolano, B

    2011-02-01

    Genetic structure and relationship amongst the main goat populations in Sicily (Girgentana, Derivata di Siria, Maltese and Messinese) were analysed using information from 19 microsatellite markers genotyped on 173 individuals. A posterior Bayesian approach implemented in the program STRUCTURE revealed a hierarchical structure with two clusters at the first level (Girgentana vs. Messinese, Derivata di Siria and Maltese), explaining 4.8% of variation (amovaФ(ST) estimate). Seven clusters nested within these first two clusters (further differentiations of Girgentana, Derivata di Siria and Maltese), explaining 8.5% of variation (amovaФ(SC) estimate). The analyses and methods applied in this study indicate their power to detect subtle population structure.

  18. Complexity of major UK companies between 2006 and 2010: Hierarchical structure method approach

    Science.gov (United States)

    Ulusoy, Tolga; Keskin, Mustafa; Shirvani, Ayoub; Deviren, Bayram; Kantar, Ersin; Çaǧrı Dönmez, Cem

    2012-11-01

    This study reports on topology of the top 40 UK companies that have been analysed for predictive verification of markets for the period 2006-2010, applying the concept of minimal spanning tree and hierarchical tree (HT) analysis. Construction of the minimal spanning tree (MST) and the hierarchical tree (HT) is confined to a brief description of the methodology and a definition of the correlation function between a pair of companies based on the London Stock Exchange (LSE) index in order to quantify synchronization between the companies. A derivation of hierarchical organization and the construction of minimal-spanning and hierarchical trees for the 2006-2008 and 2008-2010 periods have been used and the results validate the predictive verification of applied semantics. The trees are known as useful tools to perceive and detect the global structure, taxonomy and hierarchy in financial data. From these trees, two different clusters of companies in 2006 were detected. They also show three clusters in 2008 and two between 2008 and 2010, according to their proximity. The clusters match each other as regards their common production activities or their strong interrelationship. The key companies are generally given by major economic activities as expected. This work gives a comparative approach between MST and HT methods from statistical physics and information theory with analysis of financial markets that may give new valuable and useful information of the financial market dynamics.

  19. Microwave-assisted synthesis and characterization of hierarchically structured calcium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhenxing [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China); Wang, Guangjian, E-mail: wgj2260@chnu.edu.cn [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China); Guo, Yajie; Kang, Fangfang; Huang, Yanhong; Bo, Dongsheng [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China)

    2012-12-15

    Graphical abstract: CaF{sub 2} with different morphologies and hierarchical structure such as dendrites, spherical and cube was prepared under microwave-assisted condition by a simple solvothermal synthesis route using CaCl{sub 2} and [BMIM]BF{sub 4} as initial reagents, respectively. It was found that the species of precursor was of vital importance for the formation of CaF{sub 2} crystals. That is, precursors itself also acted as structure directing agent. The outstanding features of the approach to obtain hierarchical structure CaF{sub 2} were its simplicity, effectiveness and ease of assembly. On the basis of the experimental results, a possible growth mechanism of the CaF{sub 2} crystals was proposed. Display Omitted Highlights: ► CaF{sub 2} with hierarchical structure was synthesized under microwave-assisted conditions. ► Characteristic morphologies with cube, dendrite, hierarchical sphere, etc. were observed. ► Thin cubes assembled into a spherical structure. ► Ionic liquid of [BMIM]BF{sub 4} was fluorine source. ► Possible growth mechanisms of CaF{sub 2} crystals were discussed. -- Abstract: CaF{sub 2} with different morphologies and hierarchical structures was prepared under microwave-assisted condition by a simple hydrothermal route using CaCl{sub 2} and ionic liquid [BMIM]BF{sub 4} as initial reagents, respectively. It was found that both the precursor and pH values played an important role in the formation of CaF{sub 2} crystals with different morphologies. The results suggested that the CaF{sub 2} with cube and spherical structures was obtained at different pH values (4, 8, 11), while the CaF{sub 2} with dendrite shape was formed through an oriented self-assembly growth using (NH{sub 4}){sub 2}HPO{sub 4} as a structure directing agent. Scanning electron microscope observation showed that the as-prepared CaF{sub 2} was of three-dimensional eight-horn-shaped dendritic structure. The influence of the pH values for the reaction solution and

  20. Assessing the multidimensional and hierarchical structure of SERVQUAL.

    Science.gov (United States)

    Ma, Jun; Harvey, Milton E; Hu, Michael Y

    2007-10-01

    Parasuraman, Zeithaml, and Berry introduced SERVQUAL in 1998 as a scale to measure service quality. Since then, researchers have proposed several variations. This study examines the development of the tool. Marketing researchers have first challenged the conceptualization of a perceptions-expectations gap and have concluded that the performance-based measures are adequate to capture consumers' perception of service quality. Some researchers have argued that the five dimensions of the SERVQUAL scale only focus on the process of service delivery and have extended the SERVQUAL scale into six dimensions by including the service outcome dimension. Others have proposed that service quality is a multilevel construct and should be measured accordingly. From a sample of 467 undergraduate students data on service quality toward up-scale restaurants were collected. Using the structural equation approach, two measurement models of service quality were compared, the extended SERVQUAL model and the restructured multilevel SERVQUAL model. Analysis suggested that the latter model fits the data better than the extended one.

  1. Hierarchical structure of the countries based on electricity consumption and economic growth

    Science.gov (United States)

    Kantar, Ersin; Aslan, Alper; Deviren, Bayram; Keskin, Mustafa

    2016-07-01

    We investigate the hierarchical structures of countries based on electricity consumption and economic growth by using the real amounts of their consumption over a certain time period. We use electricity consumption data to detect the topological properties of 64 countries from 1971 to 2008. These countries are divided into three clusters: low income group, middle income group and high income group countries. Firstly, a relationship between electricity consumption and economic growth is investigated by using the concept of hierarchical structure methods (minimal spanning tree (MST) and hierarchical tree (HT)). Secondly, we perform bootstrap techniques to investigate a value of the statistical reliability to the links of the MST. Finally, we use a clustering linkage procedure in order to observe the cluster structure more clearly. The results of the structural topologies of these trees are as follows: (i) we identified different clusters of countries according to their geographical location and economic growth, (ii) we found a strong relation between energy consumption and economic growth for all the income groups considered in this study and (iii) the results are in good agreement with the causal relationship between electricity consumption and economic growth.

  2. Hierarchically structured composites for ultrafast liquid sensing and smart leak-plugging.

    Science.gov (United States)

    Wu, Xiaodong; Han, Yangyang; Zhang, Xinxing; Lu, Canhui

    2017-06-21

    Conductive polymer composites (CPCs) have been intensively exploited as remarkable liquid sensing materials based on variations in their conductivity under liquid stimuli. However, most advances in liquid sensing CPCs are limited to bulk materials. Due to the slow permeation of liquids into the compact CPCs, sluggish responses are inevitable for most existing CPC-based liquid sensing materials. Here, we developed a new class of liquid sensing materials via a hierarchical structure design. Specifically, a thin CPC layer with a segregated conductive network was coated on porous polyurethane (PU) skeletons by layer-by-layer assembly, forming an elaborately designed hierarchical structure in the prepared CPC@PU composites. With this hierarchical structure, the CPC@PU composites exhibited ultrafast responses (0.05-0.15 s) to solvent stimuli, which are ∼3 orders of magnitude faster than the state-of-the-art composites. After liquid sensing, quick regeneration (within 10 s) could be achieved under hot-air. Accordingly, organic liquid and gas sensors and liquid-sensing electronic skins were fabricated. Furthermore, we prepared smart and fast leak-plugging materials using the CPC@PU composites based on the swelling-induced blocking of micropores in the materials. This structural strategy proposed here opens up exciting avenues towards manufacturing real-time liquid sensing and plugging materials, revealing potential applications in oilfield exploitation, solvent storage/transportation, environmental monitoring, etc.

  3. Hierarchically structured carbon nanotubes for energy conversion and storage

    Science.gov (United States)

    Du, Feng

    As the world population continues to increase, large amounts of energy are consumed. Reality pushes us to find new energy or use our current energy more efficiently. Researches on energy conversion and storage have become increasingly important and essential. This grand challenge research has led to a recent focus on nanostructured materials. Carbon nanomaterials such as carbon nanotubes (CNTs) play a critical role in all of these nanotechnology challenges. CNTs have a very large surface area, a high electrochemical accessibility, high electronic conductivity and strong mechanical properties. This combination of properties makes them promising materials for energy device applications, such as FETs, supercapacitors, fuel cells, and lithium batteries. This study focuses on exploring the possibility of using vertically aligned carbon nanotubes (VA-CNTs) as the electrode materials in these energy applications. For the application of electrode materials, electrical conductive, vertically aligned CNTs with controllable length and diameter were synthesized. Several CVD methods for VA-CNT growth have been explored, although the iron / aluminum pre-coated catalyst CVD system was the main focus. A systematic study of several factors, including growth time, temperature, gas ratio, catalyst coating was conducted. The mechanism of VA-CNTs was discussed and a model for VA-CNT length / time was proposed to explain the CNT growth rate. Furthermore, the preferential growth of semiconducting (up to 96 atom% carbon) VA-SWNTs by using a plasma enhanced CVD process combined with fast heating was also explored, and these semiconducting materials have been directly used for making FETs using simple dispersion in organic solvent, without any separation and purification. Also, by inserting electron-accepting nitrogen atoms into the conjugated VA-CNT structure during the growth process, we synthesized vertically aligned nitrogen containing carbon nanotubes (VA-NCNTs). After purification of

  4. CTAB-Assisted Hydrothermal Synthesis of WO3 Hierarchical Porous Structures and Investigation of Their Sensing Properties

    Directory of Open Access Journals (Sweden)

    Dan Meng

    2015-01-01

    Full Text Available WO3 hierarchical porous structures were successfully synthesized via cetyltrimethylammonium bromide- (CTAB- assisted hydrothermal method. The structure and morphology were investigated using scanning electron microscope, X-ray diffractometer, transmission electron microscopy, X-ray photoelectron spectra, Brunauer-Emmett-Teller nitrogen adsorption-desorption, and thermogravimetry and differential thermal analysis. The result demonstrated that WO3 hierarchical porous structures with an orthorhombic structure were constructed by a number of nanoparticles about 50–100 nm in diameters. The H2 gas sensing measurements showed that well-defined WO3 hierarchical porous structures with a large specific surface area exhibited the higher sensitivity compared with products without CTAB at all operating temperatures. Moreover, the reversible and fast response to H2 gas and good selectivity were obtained. The results indicated that the WO3 hierarchical porous structures are promising materials for gas sensors.

  5. Rapid fabrication of hierarchically structured supramolecular nanocomposite thin films in one minute

    Science.gov (United States)

    Xu, Ting; Kao, Joseph

    2016-11-08

    Functional nanocomposites containing nanoparticles of different chemical compositions may exhibit new properties to meet demands for advanced technology. It is imperative to simultaneously achieve hierarchical structural control and to develop rapid, scalable fabrication to minimize degradation of nanoparticle properties and for compatibility with nanomanufacturing. The assembly kinetics of supramolecular nanocomposite in thin films is governed by the energetic cost arising from defects, the chain mobility, and the activation energy for inter-domain diffusion. By optimizing only one parameter, the solvent fraction in the film, the assembly kinetics can be precisely tailored to produce hierarchically structured thin films of supramolecular nanocomposites in approximately one minute. Moreover, the strong wavelength dependent optical anisotropy in the nanocomposite highlights their potential applications for light manipulation and information transmission. The present invention opens a new avenue in designing manufacture-friendly continuous processing for the fabrication of functional nanocomposite thin films.

  6. Hierarchically structured photonic crystals for integrated chemical separation and colorimetric detection.

    Science.gov (United States)

    Fu, Qianqian; Zhu, Biting; Ge, Jianping

    2017-02-16

    A SiO2 colloidal photonic crystal film with a hierarchical porous structure is fabricated to demonstrate an integrated separation and colorimetric detection of chemical species for the first time. This new photonic crystal based thin layer chromatography process requires no dyeing, developing and UV irradiation compared to the traditional TLC. The assembling of mesoporous SiO2 particles via a supersaturation-induced-precipitation process forms uniform and hierarchical photonic crystals with micron-scale cracks and mesopores, which accelerate the diffusion of developers and intensify the adsorption/desorption between the analytes and silica for efficient separation. Meanwhile, the chemical substances infiltrated to the voids of photonic crystals cause an increase of the refractive index and a large contrast of structural colors towards the unloaded part, so that the sample spots can be directly recognized with the naked eye before and after separation.

  7. Hierarchical statistical shape models of multiobject anatomical structures: application to brain MRI.

    Science.gov (United States)

    Cerrolaza, Juan J; Villanueva, Arantxa; Cabeza, Rafael

    2012-03-01

    The accurate segmentation of subcortical brain structures in magnetic resonance (MR) images is of crucial importance in the interdisciplinary field of medical imaging. Although statistical approaches such as active shape models (ASMs) have proven to be particularly useful in the modeling of multiobject shapes, they are inefficient when facing challenging problems. Based on the wavelet transform, the fully generic multiresolution framework presented in this paper allows us to decompose the interobject relationships into different levels of detail. The aim of this hierarchical decomposition is twofold: to efficiently characterize the relationships between objects and their particular localities. Experiments performed on an eight-object structure defined in axial cross sectional MR brain images show that the new hierarchical segmentation significantly improves the accuracy of the segmentation, and while it exhibits a remarkable robustness with respect to the size of the training set.

  8. Rapid fabrication of hierarchically structured supramolecular nanocomposite thin films in one minute

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ting; Kao, Joseph

    2016-11-08

    Functional nanocomposites containing nanoparticles of different chemical compositions may exhibit new properties to meet demands for advanced technology. It is imperative to simultaneously achieve hierarchical structural control and to develop rapid, scalable fabrication to minimize degradation of nanoparticle properties and for compatibility with nanomanufacturing. The assembly kinetics of supramolecular nanocomposite in thin films is governed by the energetic cost arising from defects, the chain mobility, and the activation energy for inter-domain diffusion. By optimizing only one parameter, the solvent fraction in the film, the assembly kinetics can be precisely tailored to produce hierarchically structured thin films of supramolecular nanocomposites in approximately one minute. Moreover, the strong wavelength dependent optical anisotropy in the nanocomposite highlights their potential applications for light manipulation and information transmission. The present invention opens a new avenue in designing manufacture-friendly continuous processing for the fabrication of functional nanocomposite thin films.

  9. Controlling Torque Distribution for Parallel Hybrid Vehicle Based on Hierarchical Structure Fuzzy Logic

    Institute of Scientific and Technical Information of China (English)

    HuangMiao-hua; JinGuo-dong

    2003-01-01

    The Hierarchical Structure Fuzzy Logic Control(HSFLC) strategies of torque distribute for Parallel Hybrid Electric Vehicle (PHEV) in the mocle of operation of the vehicle i. e. , acceleration, cruise, deceleration etc. have been studied. Using secondly developed the hybrid vehicle simulation tool ADVISOR, the dynamic model of PHEV has been set up by MATLAB/SIMULINK. The engine, motor as well as the battery characteristics have been studied. Simulation results show that the proposed hierarchical structured fuzzy logic control strategy is effective over the entire operating range of the vehicle in terms of fuel economy. Based on the analyses of the simulation results and driver's experiences, a fuzzy controller is designed and developed to control the torque distribution. The controller is evaluated via hardware-in-the-loop simulator (HILS). The results show that controller verify its value.

  10. Spatio-temporal map generalizations with the hierarchical Voronoi data structure

    DEFF Research Database (Denmark)

    Mioc, Darka; Anton, François; Gold, Christopher M.

    of map objects, together with their temporal and spatial adjacency relationships. In this paper, we present new solutions to the problems of spatio-temporal generalizations using the hierarchical Voronoi spatio-temporal data structure. The application of the hierarchical Voronoi data structure presented...... in this research is in spatio-temporal map generalization, which is needed for reasoning about dynamic aspects of the world, primarily about actions, events and processes. This provides an advance in the domain of map generalization as we are able to deal not only with the cartographic objects, but also...... implemented in commercial GIS systems. In this research, we used the Voronoi spatial data model for map generalizations. We were able to demonstrate that the map generalization does not affect only spatial objects (points, lines or polygons), but also the events corresponding to the creation and modification...

  11. 3D NEAREST NEIGHBOUR SEARCH USING A CLUSTERED HIERARCHICAL TREE STRUCTURE

    Directory of Open Access Journals (Sweden)

    A. Suhaibah

    2016-06-01

    Full Text Available Locating and analysing the location of new stores or outlets is one of the common issues facing retailers and franchisers. This is due to assure that new opening stores are at their strategic location to attract the highest possible number of customers. Spatial information is used to manage, maintain and analyse these store locations. However, since the business of franchising and chain stores in urban areas runs within high rise multi-level buildings, a three-dimensional (3D method is prominently required in order to locate and identify the surrounding information such as at which level of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN analysis. It uses a point location and identifies the surrounding neighbours. However, with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results are presented in this paper. Another advantage of this structure is that it also offers a minimal overlap and coverage among nodes which can reduce repetitive data entry.

  12. MODEM: a multi-agent hierarchical structure to model the human motor control system.

    Science.gov (United States)

    Emadi Andani, Mehran; Bahrami, Fariba; Jabehdar Maralani, Parviz; Ijspeert, Auke Jan

    2009-12-01

    In this study, based on behavioral and neurophysiological facts, a new hierarchical multi-agent architecture is proposed to model the human motor control system. Performance of the proposed structure is investigated by simulating the control of sit to stand movement. To develop the model, concepts of mixture of experts, modular structure, and some aspects of equilibrium point hypothesis were brought together. We have called this architecture MODularized Experts Model (MODEM). Human motor system is modeled at the joint torque level and the role of the muscles has been embedded in the function of the joint compliance characteristics. The input to the motor system, i.e., the central command, is the reciprocal command. At the lower level, there are several experts to generate the central command to control the task according to the details of the movement. The number of experts depends on the task to be performed. At the higher level, a "gate selector" block selects the suitable subordinate expert considering the context of the task. Each expert consists of a main controller and a predictor as well as several auxiliary modules. The main controller of an expert learns to control the performance of a given task by generating appropriate central commands under given conditions and/or constraints. The auxiliary modules of this expert learn to scrutinize the generated central command by the main controller. Auxiliary modules increase their intervention to correct the central command if the movement error is increased due to an external disturbance. Each auxiliary module acts autonomously and can be interpreted as an agent. Each agent is responsible for one joint and, therefore, the number of the agents of each expert is equal to the number of joints. Our results indicate that this architecture is robust against external disturbances, signal-dependent noise in sensory information, and changes in the environment. We also discuss the neurophysiological and behavioral basis of

  13. UV-assisted capillary force lithography for engineering biomimetic multiscale hierarchical structures: From lotus leaf to gecko foot hairs

    KAUST Repository

    Jeong, Hoon Eui

    2009-01-01

    This feature article provides an overview of the recently developed two-step UV-assisted capillary force lithography and its application to fabricating well-defined micro/nanoscale hierarchical structures. This method utilizes an oxygen inhibition effect in the course of UV irradiation curing and a two-step moulding process, to form multiscale hierarchical or suspended nanobridge structures in a rapid and reproducible manner. After a brief description of the fabrication principles, several examples of the two-step UV-assisted moulding technique are presented. In addition, emerging applications of the multiscale hierarchical structures are briefly described. © The Royal Society of Chemistry 2009.

  14. The Relationship between Self-Leadership and Personality: A Comparison of Hierarchical Factor Structures

    OpenAIRE

    Jeffery D. Houghton

    2000-01-01

    This study examined the relationship between self-leadership and personality through an analysis and comparison of hierarchical factor structures. More specifically, this study examined the relationships between the self-leadership dimensions of behavior-focused strategies, natural reward strategies, and constructive thought strategies, and the personality dimensions of extraversion, emotional stability, and conscientiousness. The results of the study provide evidence that the self-leadershi...

  15. structSSI: Simultaneous and Selective Inference for Grouped or Hierarchically Structured Data

    Directory of Open Access Journals (Sweden)

    Kris Sankaran

    2014-09-01

    We briefly describe the group Benjamini-Hochberg and hierarchical false discovery rate procedures and then illustrate them using two examples, one a measure of ecological microbial abundances and the other a global temperature time series. For both procedures, we detail the steps associated with the analysis of these particular data sets, including establishing the dependence structures, performing the test, and interpreting the results. These steps are encapsulated by R functions, and we explain their applicability to general data sets.

  16. HIERARCHICAL STRUCTURE OF MAGNETOHYDRODYNAMIC TURBULENCE IN POSITION-POSITION-VELOCITY SPACE

    Energy Technology Data Exchange (ETDEWEB)

    Burkhart, Blakesley; Lazarian, A. [Astronomy Department, University of Wisconsin, Madison, 475 N. Charter St., WI 53711 (United States); Goodman, Alyssa [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); Rosolowsky, Erik [University of British Columbia, Okanagan Campus, 3333 University Way, Kelowna BC V1V 1V7 (Canada)

    2013-06-20

    Magnetohydrodynamic turbulence is able to create hierarchical structures in the interstellar medium (ISM) that are correlated on a wide range of scales via the energy cascade. We use hierarchical tree diagrams known as dendrograms to characterize structures in synthetic position-position-velocity (PPV) emission cubes of isothermal magnetohydrodynamic turbulence. We show that the structures and degree of hierarchy observed in PPV space are related to the presence of self-gravity and the global sonic and Alfvenic Mach numbers. Simulations with higher Alfvenic Mach number, self-gravity and supersonic flows display enhanced hierarchical structure. We observe a strong dependency on the sonic and Alfvenic Mach numbers and self-gravity when we apply the statistical moments (i.e., mean, variance, skewness, kurtosis) to the leaf and node distribution of the dendrogram. Simulations with self-gravity, larger magnetic field and higher sonic Mach number have dendrogram distributions with higher statistical moments. Application of the dendrogram to three-dimensional density cubes, also known as position-position-position (PPP) cubes, reveals that the dominant emission contours in PPP and PPV are related for supersonic gas but not for subsonic. We also explore the effects of smoothing, thermal broadening, and velocity resolution on the dendrograms in order to make our study more applicable to observational data. These results all point to hierarchical tree diagrams as being a promising additional tool for studying ISM turbulence and star forming regions for obtaining information on the degree of self-gravity, the Mach numbers and the complicated relationship between PPV and PPP data.

  17. A Hierarchical FEM approach for Simulation of Geometrical and Material induced Instability of Composite Structures

    DEFF Research Database (Denmark)

    Hansen, Anders L.; Lund, Erik; Pinho, Silvestre T.

    2009-01-01

    In this paper a hierarchical FE approach is utilized to simulate delamination in a composite plate loaded in uni-axial compression. Progressive delamination is modelled by use of cohesive interface elements that are automatically embedded. The non-linear problem is solved quasi-statically in which...... the interaction between material degradation and structural instability is solved iteratively. The effect of fibre bridging is studied numerically and in-plane failure is predicted using physically based failure criteria....

  18. Synthesis, structure and properties of hierarchical nanostructured porous materials studied by molecular dynamics simulations

    Science.gov (United States)

    Chae, Kisung

    For applications of porous materials in many fields of technological importance, such as catalysis, filtration, separation, energy storage and conversion, the efficiency is often limited by chemical kinetics, and/or diffusion of reactants and products to and from the active sites. Hierarchical nanostructured porous materials (HNPMs) that possess both mesopores (2 nm size size size and the pore wall roughness as well as the microporous structure such as the density and the graphitic pore walls can be independently controlled by synthesis parameters, such as the size of the template, the interaction strength between the template and carbon source, the initial carbon density and the quench rate, respectively. These atomic models allowed us to quantify the structure-mechanical properties relation in aligned carbon nanotubes/amorphous porous carbon nanocomposites. Our study shows that there is an optimum balance between the crystallinity of CNTs and the number bridging bonds between CNTs and the microporous matrix in order for the nanocomposites to have desired mechanical properties such as high stiffness and high buckling resistance under compressive loading. We further used these models to study the effects of the mesopore size and the pore wall roughness on the transport behaviors of methane in HNPCs. Our study shows that some defects in the mesopore walls do not have a significant effect on transport properties, especially in large channels. However, when the walls of small channels become rough, adsorption and transport behaviors change dramatically. Our study shows that the enhanced flow in CNTs observed in experiments is mainly due to the smooth potential energy surface of CNTs with high quality of graphitic walls. In order to carry out a systematic study on pressure-driven gas transport in HNPCs, a computationally efficient reflecting particle method (RPM) together with a perturbation-relaxation loop was developed in this work to make the pressure drop

  19. Thermodynamic analysis on an anisotropically superhydrophobic surface with a hierarchical structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jieliang [Division of Intelligent and Biomechanical Systems, State Key Laboratory of Tribology, Tsinghua University, Room 3407, Building 9003, 100084 Beijing (China); Su, Zhengliang [Division of Intelligent and Biomechanical Systems, State Key Laboratory of Tribology, Tsinghua University, Room 3407, Building 9003, 100084 Beijing (China); Department of Automotive Engineering, Tsinghua University, Beijing 100084 (China); Yan, Shaoze, E-mail: yansz@mail.tsinghua.edu.cn [Division of Intelligent and Biomechanical Systems, State Key Laboratory of Tribology, Tsinghua University, Room 3407, Building 9003, 100084 Beijing (China)

    2015-12-01

    Graphical abstract: - Highlights: • We model the superhydrophobic surface with anisotropic and hierarchical structure. • Anisotropic wetting only shows in noncomposite state (not in composite state). • Transition from noncomposite to composite state on dual-scale structure is hard. • Droplets tend to roll in the particular direction. • Droplets tend to stably remain in one preferred thermodynamic state. - Abstract: Superhydrophobic surfaces, which refer to the surfaces with contact angle higher than 150° and hysteresis less than 10°, have been reported in various studies. However, studies on the superhydrophobicity of anisotropic, hierarchical surfaces are limited and the corresponding thermodynamic mechanisms could not be explained thoroughly. Here we propose a simplified surface model of anisotropic patterned surface with dual scale roughness. Based on the thermodynamic method, we calculate the equilibrium contact angle (ECA) and the contact angle hysteresis (CAH) on the given surface. We show here that the hierarchical structure has much better anisotropic wetting properties than the single-scale one, and the results shed light on the potential application in controllable micro-/nano-fluidic systems. Our studies can be potentially applied for the fabrication of anisotropically superhydrophobic surfaces.

  20. GENETIC CONSEQUENCES OF SEED DISPERSAL IN THREE SYMPATRIC FOREST HERBS. I. HIERARCHICAL POPULATION-GENETIC STRUCTURE.

    Science.gov (United States)

    Williams, Charles F; Guries, Raymond P

    1994-06-01

    To examine the effects of seed dispersal on spatial genetic structure, we compare three sympatric species of forest herbs in the family Apiaceae whose fruits differ widely in morphological adaptations for animal-attached dispersal. Cryptotaenia canadensis has smooth fruits that are gravity dispersed, whereas Osmorhiza claytonii and Sanicula odorata fruits have appendages that facilitate their attachment to animals. The relative seed-dispersal ability among species, measured as their ability to remain attached to mammal fur, is ranked Sanicula > Osmorhiza > Cryptotaenia. We use a nested hierarchical sampling design to analyze genetic structure at spatial scales ranging from a few meters to hundreds of kilometers. Genetic differentiation among population subdivisions, estimated by average genetic distance and hierarchical F-statistics, has an inverse relationship with dispersal ability such that Cryptotaenia > Osmorhiza > Sanicula. In each species, genetic differentiation increases with distance among population subdivisions. Stochastic variation in gene flow, arising from seed dispersal by attachment to animals, may partly explain the weak relationship between pairwise spatial and genetic distance among populations and heterogeneity in estimates of single locus F-statistics. A hierarchical island model of gene flow is invoked to describe the effects of seed dispersal on population genetic structure. Seed dispersal is the predominant factor affecting variation in gene flow among these ecologically similar, taxonomically related species. © 1994 The Society for the Study of Evolution.

  1. Inferring a district-based hierarchical structure of social contacts from census data.

    Directory of Open Access Journals (Sweden)

    Z Yu

    Full Text Available Researchers have recently paid attention to social contact patterns among individuals due to their useful applications in such areas as epidemic evaluation and control, public health decisions, chronic disease research and social network research. Although some studies have estimated social contact patterns from social networks and surveys, few have considered how to infer the hierarchical structure of social contacts directly from census data. In this paper, we focus on inferring an individual's social contact patterns from detailed census data, and generate various types of social contact patterns such as hierarchical-district-structure-based, cross-district and age-district-based patterns. We evaluate newly generated contact patterns derived from detailed 2011 Hong Kong census data by incorporating them into a model and simulation of the 2009 Hong Kong H1N1 epidemic. We then compare the newly generated social contact patterns with the mixing patterns that are often used in the literature, and draw the following conclusions. First, the generation of social contact patterns based on a hierarchical district structure allows for simulations at different district levels. Second, the newly generated social contact patterns reflect individuals social contacts. Third, the newly generated social contact patterns improve the accuracy of the SEIR-based epidemic model.

  2. Fluctuation relations between hierarchical kinetically equivalent networks with Arrhenius-type transitions and their roles in systems and structural biology

    Science.gov (United States)

    Deng, De-Ming; Lu, Yi-Ta; Chang, Cheng-Hung

    2017-06-01

    The legality of using simple kinetic schemes to determine the stochastic properties of a complex system depends on whether the fluctuations generated from hierarchical equivalent schemes are consistent with one another. To analyze this consistency, we perform lumping processes on the stochastic differential equations and the generalized fluctuation-dissipation theorem and apply them to networks with the frequently encountered Arrhenius-type transition rates. The explicit Langevin force derived from those networks enables us to calculate the state fluctuations caused by the intrinsic and extrinsic noises on the free energy surface and deduce their relations between kinetically equivalent networks. In addition to its applicability to wide classes of network related systems, such as those in structural and systems biology, the result sheds light on the fluctuation relations for general physical variables in Keizer's canonical theory.

  3. On Hierarchical Extensions of Large-Scale 4-regular Grid Network Structures

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Patel, A.; Knudsen, Thomas Phillip

    It is studied how the introduction of ordered hierarchies in 4-regular grid network structures decreses distances remarkably, while at the same time allowing for simple topological routing schemes. Both meshes and tori are considered; in both cases non-hierarchical structures have power law......, and it is shown that while they allow for more flexibility in design and construction of structures supporting topological routing, their performances are comparable to the performance of the perfect square mesh. Finally suggestions for further research within the field are given....

  4. On Hierarchical Extensions of Large-Scale 4-regular Grid Network Structures

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Patel, A.; Knudsen, Thomas Phillip

    2004-01-01

    It is studied how the introduction of ordered hierarchies in 4-regular grid network structures decreases distances remarkably, while at the same time allowing for simple topological routing schemes. Both meshes and tori are considered; in both cases non-hierarchical structures have power law......, and it is shown that while they allow for more flexibility in design and construction of structures supporting topological routing, their performances are comparable to the performance of the perfect square mesh. Finally suggestions for further research within the field are given....

  5. About Hierarchical XML Structures, Replacement of Relational Data Structures in Construction and Implementation of ERP Systems

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available The projects essential objective is to develop a new ERP system, of homogeneous nature, based on XML structures, as a possible replacement for classic ERP systems. The criteria that guide the objective definition are modularity, portability and Web connectivity. This objective is connected to a series of secondary objectives, considering that the technological approach will be filtered through the economic, social and legislative environment for a validation-by-context study. Statistics and cybernetics are to be used for simulation purposes. The homogeneous approach is meant to provide strong modularity and portability, in relation with the n-tier principles, but the main advantage of the model is its opening to the semantic Web, based on a Small enterprise ontology defined with XML-driven languages. Shockwave solutions will be used for implementing client-oriented hypermedia elements and an XML Gate will be de-fined between black box modules, for a clear separation with obvious advantages. Security and the XMLTP project will be an important issue for XML transfers due to the conflict between the open architecture of the Web, the readability of XML data and the privacy elements which have to be preserved within a business environment. The projects finality is oriented on small business but the semantic Web perspective and the surprising new conflict between hierarchical/network data structures and relational ones will certainly widen its scope. The proposed model is meant to fulfill the IT compatibility requirements of the European environment, defined as a knowledge society. The paper is a brief of the contributions of the team re-search at the project type A applied to CNCSIS "Research on the Role of XML in Building Extensible and Homogeneous ERP Systems".

  6. Synthesis and characterization of branched yttrium hydroxide fluoride microcrystals with hierarchical tubular structure

    Institute of Scientific and Technical Information of China (English)

    TIAN Li; JIANG Wentao; SUN Qiliang; LIU Jin

    2012-01-01

    Hexagonal yttrium hydroxide fluoride microcrystals were prepared by a two-step hydrothermal route using yttrium nitrate,sodium hydroxide and sodium fluoride as raw materials to react in propanetriol solvent.The samples were characterized by powder X-ray diffraction (XRD),energy dispersive spectrum (EDS),scanning electron microscopy (SEM),transmission electron microscopy (TEM),Fourier transform infrared spectroscopy (FT-IR),thermogravimetre and differential-thermogravimetric analysis (TG-DTA),which revealed that Y(OH)2.14F0.86 microcrystals were multi-branched and that the branches of Y(OH)2.14F0.86 microcrystals were composed of hierarchical tubes.This novel multi-branched and intriguing hierarchical tubular structure of yttrium hydroxide fluoride maybe has a potential application in photoelectric crystals.The formation of branched Y(OH)2.14F0.86 microcrystals with hierarchical tubular structure were due to the substitution reaction and Oswald ripening.

  7. Identifying overlapping and hierarchical thematic structures in networks of scholarly papers: a comparison of three approaches.

    Science.gov (United States)

    Havemann, Frank; Gläser, Jochen; Heinz, Michael; Struck, Alexander

    2012-01-01

    The aim of this paper is to introduce and assess three algorithms for the identification of overlapping thematic structures in networks of papers. We implemented three recently proposed approaches to the identification of overlapping and hierarchical substructures in graphs and applied the corresponding algorithms to a network of 492 information-science papers coupled via their cited sources. The thematic substructures obtained and overlaps produced by the three hierarchical cluster algorithms were compared to a content-based categorisation, which we based on the interpretation of titles, abstracts, and keywords. We defined sets of papers dealing with three topics located on different levels of aggregation: h-index, webometrics, and bibliometrics. We identified these topics with branches in the dendrograms produced by the three cluster algorithms and compared the overlapping topics they detected with one another and with the three predefined paper sets. We discuss the advantages and drawbacks of applying the three approaches to paper networks in research fields.

  8. Identifying overlapping and hierarchical thematic structures in networks of scholarly papers: a comparison of three approaches.

    Directory of Open Access Journals (Sweden)

    Frank Havemann

    Full Text Available The aim of this paper is to introduce and assess three algorithms for the identification of overlapping thematic structures in networks of papers. We implemented three recently proposed approaches to the identification of overlapping and hierarchical substructures in graphs and applied the corresponding algorithms to a network of 492 information-science papers coupled via their cited sources. The thematic substructures obtained and overlaps produced by the three hierarchical cluster algorithms were compared to a content-based categorisation, which we based on the interpretation of titles, abstracts, and keywords. We defined sets of papers dealing with three topics located on different levels of aggregation: h-index, webometrics, and bibliometrics. We identified these topics with branches in the dendrograms produced by the three cluster algorithms and compared the overlapping topics they detected with one another and with the three predefined paper sets. We discuss the advantages and drawbacks of applying the three approaches to paper networks in research fields.

  9. Thermodynamic analysis on an anisotropically superhydrophobic surface with a hierarchical structure

    Science.gov (United States)

    Zhao, Jieliang; Su, Zhengliang; Yan, Shaoze

    2015-12-01

    Superhydrophobic surfaces, which refer to the surfaces with contact angle higher than 150° and hysteresis less than 10°, have been reported in various studies. However, studies on the superhydrophobicity of anisotropic, hierarchical surfaces are limited and the corresponding thermodynamic mechanisms could not be explained thoroughly. Here we propose a simplified surface model of anisotropic patterned surface with dual scale roughness. Based on the thermodynamic method, we calculate the equilibrium contact angle (ECA) and the contact angle hysteresis (CAH) on the given surface. We show here that the hierarchical structure has much better anisotropic wetting properties than the single-scale one, and the results shed light on the potential application in controllable micro-/nano-fluidic systems. Our studies can be potentially applied for the fabrication of anisotropically superhydrophobic surfaces.

  10. Chiral acidic amino acids induce chiral hierarchical structure in calcium carbonate

    Science.gov (United States)

    Jiang, Wenge; Pacella, Michael S.; Athanasiadou, Dimitra; Nelea, Valentin; Vali, Hojatollah; Hazen, Robert M.; Gray, Jeffrey J.; McKee, Marc D.

    2017-04-01

    Chirality is ubiquitous in biology, including in biomineralization, where it is found in many hardened structures of invertebrate marine and terrestrial organisms (for example, spiralling gastropod shells). Here we show that chiral, hierarchically organized architectures for calcium carbonate (vaterite) can be controlled simply by adding chiral acidic amino acids (Asp and Glu). Chiral, vaterite toroidal suprastructure having a `right-handed' (counterclockwise) spiralling morphology is induced by L-enantiomers of Asp and Glu, whereas `left-handed' (clockwise) morphology is induced by D-enantiomers, and sequentially switching between amino-acid enantiomers causes a switch in chirality. Nanoparticle tilting after binding of chiral amino acids is proposed as a chiral growth mechanism, where a `mother' subunit nanoparticle spawns a slightly tilted, consequential `daughter' nanoparticle, which by amplification over various length scales creates oriented mineral platelets and chiral vaterite suprastructures. These findings suggest a molecular mechanism for how biomineralization-related enantiomers might exert hierarchical control to form extended chiral suprastructures.

  11. Hierarchically Structured Graphene Coupled Microporous Organic Polymers for Superior CO2 Capture.

    Science.gov (United States)

    Liu, Fa-Qian; Wang, Li-Li; Li, Guo-Hua; Li, Wei; Li, Chao-Qin

    2017-10-04

    Hierarchically porous materials containing interconnected macro-/meso-/micropores are promising candidates for energy storage, catalysis, and gas separation. Here, we present an effective approach for synthesizing three-dimensional (3D) sulfonated graphene coupled microporous organic polymers (SG-MOPs). The resulting SG-MOPs possess uniform macropores with an average size of ca. 350 nm, abundant mesopores, and micropores with an average size of ca. 0.6 nm. The SG-supported adsorbents exhibit a high nitrogen content (more than 38.1 wt %), high adsorption capacity (up to 3.37 mmol CO2 g(-1)), high CO2/N2 selectivity from 42 to 51, moderate heat of adsorption, as well as good stability because of the hierarchical porous structure and excellent thermal conductivity of the SG scaffold. Thus, these nitrogen-enriched adsorbents allow the overall CO2 capture process to be promising and sustainable.

  12. Facile method for preparing superoleophobic surfaces with hierarchical microcubic/nanowire structures

    Science.gov (United States)

    Kwak, Wonshik; Hwang, Woonbong

    2016-02-01

    To facilitate the fabrication of superoleophobic surfaces having hierarchical microcubic/nanowire structures (HMNS), even for low surface tension liquids including octane (surface tension = 21.1 mN m-1), and to understand the influences of surface structures on the oleophobicity, we developed a convenient method to achieve superoleophobic surfaces on aluminum substrates using chemical acid etching, anodization and fluorination treatment. The liquid repellency of the structured surface was validated through observable experimental results the contact and sliding angle measurements. The etching condition required to ensure high surface roughness was established, and an optimal anodizing condition was determined, as a critical parameter in building the superoleophobicity. The microcubic structures formed by acid etching are essential for achieving the formation of the hierarchical structure, and therefore, the nanowire structures formed by anodization lead to an enhancement of the superoleophobicity for low surface tension liquids. Under optimized morphology by microcubic/nanowire structures with fluorination treatment, the contact angle over 150° and the sliding angle less than 10° are achieved even for octane.

  13. Spatial Object Aggregation Based on Data Structure,Local Triangulation and Hierarchical Analyzing Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper focuses on the methods and process of spatial aggregation based on semantic and geometric characteristics of spatial objects and relations among the objects with the help of spatial data structure (Formal Data Structure),the Local Constrained Delaunay Triangulations and semantic hierarchy.The adjacent relation among connected objects and unconnected objects has been studied through constrained triangle as elementary processing unit in aggregation operation.The hierarchical semantic analytical matrix is given for analyzing the similarity between objects types and between objects.Several different cases of aggregation have been presented in this paper.

  14. Hierarchically structured carbonaceous foams generation and their use as electrochemical energy storage devices

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Nicolas [Centre de Recherche Paul Pascal, Pessac (France); Institut des Sciences Moleculaires, Talence (France); Prabaharan, Savari R.S.; Morcrette, Mathieu [Laboratoire de Reactivite et de Chimie des Solides, Amiens (France); Pecastaing, Gilles [Laboratoire de Chimie des Polymeres Organiques, Pessac (France); Birot, Marc; Deleuze, Herve [Institut des Sciences Moleculaires, Talence (France); Backov, Renal [Centre de Recherche Paul Pascal, Pessac (France)

    2010-07-01

    Hierarchically structured carbonaceous foams with a high control over macro-meso-microporous structures have been synthesized, using silica as inorganic exotemplate and phenolic resin as carbon precursor. These monolithic foams have been thoroughly characterized over all length scales. The applications of this new series of macrocellular carbonaceous monoliths as negative electrodes for Lithium-ion batteries devices (stable capacity of 200 mAh.g{sup -1}, during 50 cycles) and electrochemical capacitors (specific capacitance of 30 F.g{sup -1} at a scan rate of 10 mV.s{sup -1}) have been checked and will be discussed. (orig.)

  15. Fabrication of semi-transparent superoleophobic thin film from fabrics and nanoparticle-based hierarchical structure

    Directory of Open Access Journals (Sweden)

    Nishizawa S.

    2013-08-01

    Full Text Available Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain resistant and antifouling materials, and microfluidics among others. Transparency is also desired with superhydrophobicity for their numerous applications; however transparency and oleophobicity are almost incompatible relationship with each other in the point of surface structure. Because oleophobicity required rougher structure at nano-micro scale than hydrophobicity, and these rough structure brings light scattering. So far, there is very few report of the compatible of transparency and superoleophobicity. In this report, we proposed the see-through type fabrics using the nanoparticle-based hierarchical structure thin film for improving both of oleophobicity and transparency. The vacant space between fibrils of fabrics has two important roles: the one is to through the light, another one is to introduce air layer to realize Cassie state of liquid droplet on thin film. To realize the low surface energy and nanoscale rough structure surface on fibrils, we used the spray method with perfluoroalkyl methacrylic copolymer (PMC, silica nano particles and volatile solvent. From the SEM image, the hierarchical structures of nanoparticle were formed uniformly on the fabrics. The transparency of thin film obtained was approximately 61% and the change of transparency between pre-coated fabrics and coated was 11%. From investigation of the surface wettability, the contact angles of oils (rapeseed oil and hexadecane and water droplet on the fabricated film were over 150 degree.

  16. Hierarchical assembly may be a way to make large information-rich structures

    CERN Document Server

    Whitelam, Stephen

    2015-01-01

    Self-assembly in the laboratory can now yield `information-rich' nanostructures in which each component is of a distinct type and has a defined spatial position. Ensuring the thermodynamic stability of such structures requires inter-component interaction energies to increase logarithmically with structure size, in order to counter the entropy gained upon mixing component types in solution. However, self-assembly in the presence of strong interactions results in general in kinetic trapping, so suggesting a limit to the size of an (equilibrium) structure that can be self-assembled from distinguishable components. Here we study numerically a two-dimensional hierarchical assembly scheme already considered in experiment. We show that this scheme is immune to the kinetic traps associated with strong `native' interactions (interactions designed to stabilize the intended structure), and so, in principle, offers a way to make large information-rich structures. In this scheme the size of an assembled structure scales e...

  17. The type I error rate for in vivo Comet assay data when the hierarchical structure is disregarded

    DEFF Research Database (Denmark)

    Hansen, Merete Kjær; Kulahci, Murat

    The Comet assay is a sensitive technique for detection of DNA strand breaks. The experimental design of in vivo Comet assay studies are often hierarchically structured, which should be reWected in the statistical analysis. However, the hierarchical structure sometimes seems to be disregarded, and...... the exposition of the statistical methodology and to suitably account for the hierarchical structure of Comet assay data whenever present.......The Comet assay is a sensitive technique for detection of DNA strand breaks. The experimental design of in vivo Comet assay studies are often hierarchically structured, which should be reWected in the statistical analysis. However, the hierarchical structure sometimes seems to be disregarded......, and this imposes considerable impact on the type I error rate. This study aims to demonstrate the implications that result from disregarding the hierarchical structure. DiUerent combinations of the factor levels as they appear in a literature study give type I error rates up to 0.51 and for all combinations...

  18. Neural mechanisms underlying the computation of hierarchical tree structures in mathematics.

    Directory of Open Access Journals (Sweden)

    Tomoya Nakai

    Full Text Available Whether mathematical and linguistic processes share the same neural mechanisms has been a matter of controversy. By examining various sentence structures, we recently demonstrated that activations in the left inferior frontal gyrus (L. IFG and left supramarginal gyrus (L. SMG were modulated by the Degree of Merger (DoM, a measure for the complexity of tree structures. In the present study, we hypothesize that the DoM is also critical in mathematical calculations, and clarify whether the DoM in the hierarchical tree structures modulates activations in these regions. We tested an arithmetic task that involved linear and quadratic sequences with recursive computation. Using functional magnetic resonance imaging, we found significant activation in the L. IFG, L. SMG, bilateral intraparietal sulcus (IPS, and precuneus selectively among the tested conditions. We also confirmed that activations in the L. IFG and L. SMG were free from memory-related factors, and that activations in the bilateral IPS and precuneus were independent from other possible factors. Moreover, by fitting parametric models of eight factors, we found that the model of DoM in the hierarchical tree structures was the best to explain the modulation of activations in these five regions. Using dynamic causal modeling, we showed that the model with a modulatory effect for the connection from the L. IPS to the L. IFG, and with driving inputs into the L. IFG, was highly probable. The intrinsic, i.e., task-independent, connection from the L. IFG to the L. IPS, as well as that from the L. IPS to the R. IPS, would provide a feedforward signal, together with negative feedback connections. We indicate that mathematics and language share the network of the L. IFG and L. IPS/SMG for the computation of hierarchical tree structures, and that mathematics recruits the additional network of the L. IPS and R. IPS.

  19. Neural mechanisms underlying the computation of hierarchical tree structures in mathematics.

    Science.gov (United States)

    Nakai, Tomoya; Sakai, Kuniyoshi L

    2014-01-01

    Whether mathematical and linguistic processes share the same neural mechanisms has been a matter of controversy. By examining various sentence structures, we recently demonstrated that activations in the left inferior frontal gyrus (L. IFG) and left supramarginal gyrus (L. SMG) were modulated by the Degree of Merger (DoM), a measure for the complexity of tree structures. In the present study, we hypothesize that the DoM is also critical in mathematical calculations, and clarify whether the DoM in the hierarchical tree structures modulates activations in these regions. We tested an arithmetic task that involved linear and quadratic sequences with recursive computation. Using functional magnetic resonance imaging, we found significant activation in the L. IFG, L. SMG, bilateral intraparietal sulcus (IPS), and precuneus selectively among the tested conditions. We also confirmed that activations in the L. IFG and L. SMG were free from memory-related factors, and that activations in the bilateral IPS and precuneus were independent from other possible factors. Moreover, by fitting parametric models of eight factors, we found that the model of DoM in the hierarchical tree structures was the best to explain the modulation of activations in these five regions. Using dynamic causal modeling, we showed that the model with a modulatory effect for the connection from the L. IPS to the L. IFG, and with driving inputs into the L. IFG, was highly probable. The intrinsic, i.e., task-independent, connection from the L. IFG to the L. IPS, as well as that from the L. IPS to the R. IPS, would provide a feedforward signal, together with negative feedback connections. We indicate that mathematics and language share the network of the L. IFG and L. IPS/SMG for the computation of hierarchical tree structures, and that mathematics recruits the additional network of the L. IPS and R. IPS.

  20. Neural Mechanisms Underlying the Computation of Hierarchical Tree Structures in Mathematics

    Science.gov (United States)

    Nakai, Tomoya; Sakai, Kuniyoshi L.

    2014-01-01

    Whether mathematical and linguistic processes share the same neural mechanisms has been a matter of controversy. By examining various sentence structures, we recently demonstrated that activations in the left inferior frontal gyrus (L. IFG) and left supramarginal gyrus (L. SMG) were modulated by the Degree of Merger (DoM), a measure for the complexity of tree structures. In the present study, we hypothesize that the DoM is also critical in mathematical calculations, and clarify whether the DoM in the hierarchical tree structures modulates activations in these regions. We tested an arithmetic task that involved linear and quadratic sequences with recursive computation. Using functional magnetic resonance imaging, we found significant activation in the L. IFG, L. SMG, bilateral intraparietal sulcus (IPS), and precuneus selectively among the tested conditions. We also confirmed that activations in the L. IFG and L. SMG were free from memory-related factors, and that activations in the bilateral IPS and precuneus were independent from other possible factors. Moreover, by fitting parametric models of eight factors, we found that the model of DoM in the hierarchical tree structures was the best to explain the modulation of activations in these five regions. Using dynamic causal modeling, we showed that the model with a modulatory effect for the connection from the L. IPS to the L. IFG, and with driving inputs into the L. IFG, was highly probable. The intrinsic, i.e., task-independent, connection from the L. IFG to the L. IPS, as well as that from the L. IPS to the R. IPS, would provide a feedforward signal, together with negative feedback connections. We indicate that mathematics and language share the network of the L. IFG and L. IPS/SMG for the computation of hierarchical tree structures, and that mathematics recruits the additional network of the L. IPS and R. IPS. PMID:25379713

  1. Hazard consistent structural demands and in-structure design response spectra

    Energy Technology Data Exchange (ETDEWEB)

    Houston, Thomas W [Los Alamos National Laboratory; Costantino, Michael C [Los Alamos National Laboratory; Costantino, Carl J [Los Alamos National Laboratory

    2009-01-01

    Current analysis methodology for the Soil Structure Interaction (SSI) analysis of nuclear facilities is specified in ASCE Standard 4. This methodology is based on the use of deterministic procedures with the intention that enough conservatism is included in the specified procedures to achieve an 80% probability of non-exceedance in the computed response of a Structure, System. or Component for given a mean seismic design input. Recently developed standards are aimed at achieving performance-based, risk consistent seismic designs that meet specified target performance goals. These design approaches rely upon accurately characterizing the probability (hazard) level of system demands due to seismic loads consistent with Probabilistic Seismic Hazard Analyses. This paper examines the adequacy of the deterministic SSI procedures described in ASCE 4-98 to achieve an 80th percentile of Non-Exceedance Probability (NEP) in structural demand, given a mean seismic input motion. The study demonstrates that the deterministic procedures provide computed in-structure response spectra that are near or greater than the target 80th percentile NEP for site profiles other than those resulting in high levels of radiation damping. The deterministic procedures do not appear to be as robust in predicting peak accelerations, which correlate to structural demands within the structure.

  2. Synthesis and Characterization of Hierarchical Structured TiO2 Nanotubes and Their Photocatalytic Performance on Methyl Orange

    Directory of Open Access Journals (Sweden)

    Kai Liu

    2015-01-01

    Full Text Available Hierarchical structured TiO2 nanotubes were prepared by mechanical ball milling of highly ordered TiO2 nanotube arrays grown by electrochemical anodization of titanium foil. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, specific surface area analysis, UV-visible absorption spectroscopy, photocurrent measurement, photoluminescence spectra, electrochemical impedance spectra, and photocatalytic degradation test were applied to characterize the nanocomposites. Surface area increased as the milling time extended. After 5 h ball milling, TiO2 hierarchical nanotubes exhibited a corn-like shape and exhibited enhanced photoelectrochemical activity in comparison to commercial P25. The superior photocatalytic activity is suggested to be due to the combined advantages of high surface area of nanoparticles and rapid electron transfer as well as collection of the nanotubes in the hierarchical structure. The hierarchical structured TiO2 nanotubes could be applied into flexible applications on solar cells, sensors, and other photoelectrochemical devices.

  3. Hierarchical system for autonomous sensing-healing of delamination in large-scale composite structures

    Science.gov (United States)

    Minakuchi, Shu; Sun, Denghao; Takeda, Nobuo

    2014-10-01

    This study combines our hierarchical fiber-optic-based delamination detection system with a microvascular self-healing material to develop the first autonomous sensing-healing system applicable to large-scale composite structures. In this combined system, embedded vascular modules are connected through check valves to a surface-mounted supply tube of a pressurized healing agent while fiber-optic-based sensors monitor the internal pressure of these vascular modules. When delamination occurs, the healing agent flows into the vascular modules breached by the delamination and infiltrates the damage for healing. At the same time, the pressure sensors identify the damaged modules by detecting internal pressure changes. This paper begins by describing the basic concept of the combined system and by discussing the advantages that arise from its hierarchical nature. The feasibility of the system is then confirmed through delamination infiltration tests. Finally, the hierarchical system is validated in a plate specimen by focusing on the detection and infiltration of the damage. Its self-diagnostic function is also demonstrated.

  4. Structural and photovoltaic characteristics of hierarchical ZnO nanostructures electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, Muhammad, E-mail: saleem.malikape@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Key Laboratory of Optoelectronic Technology and Systems of the Education Ministry of China, Chongqing University, Chongqing 400044 (China); Fang, L. [Key Laboratory of Optoelectronic Technology and Systems of the Education Ministry of China, Chongqing University, Chongqing 400044 (China); Shaukat, Saleem F.; Ahmad, M. Ashfaq [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Raza, Rizwan, E-mail: razahussaini786@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Akhtar, Majid Niaz; Jamil, Ayesha; Aslam, Samia [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Abbas, Ghazanfar [Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2015-04-15

    Highlights: • Hierarchically ZnO nanostructures electrodes were grown using hot plate magnetic stirring at different growth reaction temperature. • We have investigated the effect of working temperature of 160°, 170°, 180°, and 190° on the growth mechanism of nanospheres and on the power conversion efficiency of DSSCs. • ZnO nanospheres with perfect aggregation show superior power conversion efficiency of 1.24% which is about 83% higher than nanoparticles DSSC. • An obvious vogue is that the overall power conversion efficiency decreases as the degree of the spherical aggregation is gradually destroyed. - Abstract: Structural and photovoltaic characteristics of hierarchical ZnO nanostructures solar cell have been studied in relation to growth reaction temperature. It is found that the hierarchical ZnO nanostructures network to act not only as large surface area substrates but also as a transport medium for electrons injected from the dye molecules. The incident photon-to-current conversion efficiency is decreased by increasing the growth reaction temperature of ZnO electrodes. The best conversion efficiency of a 0.25 cm{sup 2} cell is measured to be 1.24% under 100 mW cm{sup −2} irradiation.

  5. Data with hierarchical structure: impact of intraclass correlation and sample size on type-I error.

    Science.gov (United States)

    Musca, Serban C; Kamiejski, Rodolphe; Nugier, Armelle; Méot, Alain; Er-Rafiy, Abdelatif; Brauer, Markus

    2011-01-01

    Least squares analyses (e.g., ANOVAs, linear regressions) of hierarchical data leads to Type-I error rates that depart severely from the nominal Type-I error rate assumed. Thus, when least squares methods are used to analyze hierarchical data coming from designs in which some groups are assigned to the treatment condition, and others to the control condition (i.e., the widely used "groups nested under treatment" experimental design), the Type-I error rate is seriously inflated, leading too often to the incorrect rejection of the null hypothesis (i.e., the incorrect conclusion of an effect of the treatment). To highlight the severity of the problem, we present simulations showing how the Type-I error rate is affected under different conditions of intraclass correlation and sample size. For all simulations the Type-I error rate after application of the popular Kish (1965) correction is also considered, and the limitations of this correction technique discussed. We conclude with suggestions on how one should collect and analyze data bearing a hierarchical structure.

  6. Data with hierarchical structure: impact of intraclass correlation and sample size on Type-I error

    Directory of Open Access Journals (Sweden)

    Serban C Musca

    2011-04-01

    Full Text Available Least squares analyses (e.g., ANOVAs, linear regressions of hierarchical data leads to Type-I error rates that depart severely from the nominal Type-I error rate assumed. Thus, when least squares methods are used to analyze hierarchical data coming from designs in which some groups are assigned to the treatment condition, and others to the control condition (i.e., the widely used "groups nested under treatment" experimental design, the Type-I error rate is seriously inflated, leading too often to the incorrect rejection of the null hypothesis (i.e., the incorrect conclusion of an effect of the treatment. To highlight the severity of the problem, we present simulations showing how the Type-I error rate is affected under different conditions of intraclass correlation and sample size. For all simulations the Type-I error rate after application of the popular Kish (1965 correction is also considered, and the limitations of this correction technique discussed. We conclude with suggestions on how one should collect and analyze data bearing a hierarchical structure.

  7. Hierarchical structures of correlations networks among Turkey’s exports and imports by currencies

    Science.gov (United States)

    Kocakaplan, Yusuf; Deviren, Bayram; Keskin, Mustafa

    2012-12-01

    We have examined the hierarchical structures of correlations networks among Turkey’s exports and imports by currencies for the 1996-2010 periods, using the concept of a minimal spanning tree (MST) and hierarchical tree (HT) which depend on the concept of ultrametricity. These trees are useful tools for understanding and detecting the global structure, taxonomy and hierarchy in financial markets. We derived a hierarchical organization and build the MSTs and HTs during the 1996-2001 and 2002-2010 periods. The reason for studying two different sub-periods, namely 1996-2001 and 2002-2010, is that the Euro (EUR) came into use in 2001, and some countries have made their exports and imports with Turkey via the EUR since 2002, and in order to test various time-windows and observe temporal evolution. We have carried out bootstrap analysis to associate a value of the statistical reliability to the links of the MSTs and HTs. We have also used the average linkage cluster analysis (ALCA) to observe the cluster structure more clearly. Moreover, we have obtained the bidimensional minimal spanning tree (BMST) due to economic trade being a bidimensional problem. From the structural topologies of these trees, we have identified different clusters of currencies according to their proximity and economic ties. Our results show that some currencies are more important within the network, due to a tighter connection with other currencies. We have also found that the obtained currencies play a key role for Turkey’s exports and imports and have important implications for the design of portfolio and investment strategies.

  8. Hierarchical robot control structure and Newton's divided difference approach to robot path planning

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A hierarchical robot control is proposed for robot soccer system. The Newton' s divided difference is utilized in robot path planning. This paper describes the problems encoutered, software design considerations, vision algorithm and controls of individual robots. The solutions.to the problems implemented are simple and di rect. It is observed that many of the ideas and solutions can be evolved based on simple theories and concepts. This paper focuses on software structure of multi-agent controls, vision algorithm and simple path planning method.

  9. Hierarchically structured lithium titanate for ultrafast charging in long-life high capacity batteries

    Science.gov (United States)

    Odziomek, Mateusz; Chaput, Frédéric; Rutkowska, Anna; Świerczek, Konrad; Olszewska, Danuta; Sitarz, Maciej; Lerouge, Frédéric; Parola, Stephane

    2017-05-01

    High-performance Li-ion batteries require materials with well-designed and controlled structures on nanometre and micrometre scales. Electrochemical properties can be enhanced by reducing crystallite size and by manipulating structure and morphology. Here we show a method for preparing hierarchically structured Li4Ti5O12 yielding nano- and microstructure well-suited for use in lithium-ion batteries. Scalable glycothermal synthesis yields well-crystallized primary 4-8 nm nanoparticles, assembled into porous secondary particles. X-ray photoelectron spectroscopy reveals presence of Ti+4 only; combined with chemical analysis showing lithium deficiency, this suggests oxygen non-stoichiometry. Electron microscopy confirms hierarchical morphology of the obtained material. Extended cycling tests in half cells demonstrates capacity of 170 mAh g-1 and no sign of capacity fading after 1,000 cycles at 50C rate (charging completed in 72 s). The particular combination of nanostructure, microstructure and non-stoichiometry for the prepared lithium titanate is believed to underlie the observed electrochemical performance of material.

  10. Hierarchical organization in the temporal structure of infant-direct speech and song.

    Science.gov (United States)

    Falk, Simone; Kello, Christopher T

    2017-06-01

    Caregivers alter the temporal structure of their utterances when talking and singing to infants compared with adult communication. The present study tested whether temporal variability in infant-directed registers serves to emphasize the hierarchical temporal structure of speech. Fifteen German-speaking mothers sang a play song and told a story to their 6-months-old infants, or to an adult. Recordings were analyzed using a recently developed method that determines the degree of nested clustering of temporal events in speech. Events were defined as peaks in the amplitude envelope, and clusters of various sizes related to periods of acoustic speech energy at varying timescales. Infant-directed speech and song clearly showed greater event clustering compared with adult-directed registers, at multiple timescales of hundreds of milliseconds to tens of seconds. We discuss the relation of this newly discovered acoustic property to temporal variability in linguistic units and its potential implications for parent-infant communication and infants learning the hierarchical structures of speech and language. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. The relationships between electricity consumption and GDP in Asian countries, using hierarchical structure methods

    Science.gov (United States)

    Kantar, Ersin; Keskin, Mustafa

    2013-11-01

    This study uses hierarchical structure methods (minimal spanning tree (MST) and hierarchical tree (HT)) to examine the relationship between energy consumption and economic growth in a sample of 30 Asian countries covering the period 1971-2008. These countries are categorized into four panels based on the World Bank income classification, namely high, upper middle, lower middle, and low income. In particular, we use the data of electricity consumption and real gross domestic product (GDP) per capita to detect the topological properties of the countries. We show a relationship between electricity consumption and economic growth by using the MST and HT. We also use the bootstrap technique to investigate a value of the statistical reliability to the links of the MST. Finally, we use a clustering linkage procedure in order to observe the cluster structure. The results of the structural topologies of these trees are as follows: (i) we identified different clusters of countries according to their geographical location and economic growth, (ii) we found a strong relationship between energy consumption and economic growth for all income groups considered in this study and (iii) the results are in good agreement with the causal relationship between electricity consumption and economic growth.

  12. Controllable synthesis of branched ZnO/Si nanowire arrays with hierarchical structure.

    Science.gov (United States)

    Huang, Shengli; Yang, Qianqian; Yu, Binbin; Li, Dingguo; Zhao, Ruisheng; Li, Shuping; Kang, Junyong

    2014-01-01

    A rational approach for creating branched ZnO/Si nanowire arrays with hierarchical structure was developed based on a combination of three simple and cost-effective synthesis pathways. The crucial procedure included growth of crystalline Si nanowire arrays as backbones by chemical etching of Si substrates, deposition of ZnO thin film as a seed layer by magnetron sputtering, and fabrication of ZnO nanowire arrays as branches by hydrothermal growth. The successful synthesis of ZnO/Si heterogeneous nanostructures was confirmed by morphologic, structural, and optical characterizations. The roles of key experimental parameters, such as the etchant solution, the substrate direction, and the seed layer on the hierarchical nanostructure formation, were systematically investigated. It was demonstrated that an etchant solution with an appropriate redox potential of the oxidant was crucial for a moderate etching speed to achieve a well-aligned Si nanowire array with solid and round surface. Meanwhile, the presence of gravity gradient was a key issue for the growth of branched ZnO nanowire arrays. The substrate should be placed vertically or facedown in contrast to the solution surface during the hydrothermal growth. Otherwise, only the condensation of the ZnO nanoparticles took place in a form of film on the substrate surface. The seed layer played another important role in the growth of ZnO nanowire arrays, as it provided nucleation sites and determined the growing direction and density of the nanowire arrays for reducing the thermodynamic barrier. The results of this study might provide insight on the synthesis of hierarchical three-dimensional nanostructure materials and offer an approach for the development of complex devices and advanced applications.

  13. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis.

    Science.gov (United States)

    Nozaki, Kosuke; Shinonaga, Togo; Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao; Tsukamoto, Masahiro; Yamashita, Kimihiro; Nagai, Akiko

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni-Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol.

  14. Toughening mystery of natural rubber deciphered by double network incorporating hierarchical structures.

    Science.gov (United States)

    Zhou, Weiming; Li, Xiangyang; Lu, Jie; Huang, Ningdong; Chen, Liang; Qi, Zeming; Li, Liangbin; Liang, Haiyi

    2014-12-16

    As an indispensible material for modern society, natural rubber possesses peerless mechanical properties such as strength and toughness over its artificial analogues, which remains a mystery. Intensive experimental and theoretical investigations have revealed the self-enhancement of natural rubber due to strain-induced crystallization. However a rigorous model on the self-enhancement, elucidating natural rubber's extraordinary mechanical properties, is obscured by deficient understanding of the local hierarchical structure under strain. With spatially resolved synchrotron radiation micro-beam scanning X-ray diffraction we discover weak oscillation in distributions of strain-induced crystallinity around crack tip for stretched natural rubber film, demonstrating a soft-hard double network structure. The fracture energy enhancement factor obtained by utilizing the double network model indicates an enhancement of toughness by 3 orders. It's proposed that upon stretching spontaneously developed double network structures integrating hierarchy at multi length-scale in natural rubber play an essential role in its remarkable mechanical performance.

  15. How Are Researching and Reading Interwieved during Retrieval from Hierarchically Structured Documents?

    DEFF Research Database (Denmark)

    Hertzum, Morten; Lalmas, M.; Frøkjær, Erik

    2001-01-01

    Effective use of information retrieval systems requires that users know when to – temporarily – cease searching to do some reading and where to start reading. In hierarchically structured documents, users can to some extent interchange searching and reading by entering the text at different levels...... in the structure. Based on an experiment where 83 subjects solved 20 tasks each, we find that the subjects spend at least one third of their time reading, irrespective of whether the system they use offers browsing and/or querying. The subjects prefer reading the text in chunks that span multiple levels...... of the structure. As much as 21% of the tasks are solved by subjects who enter the text at a level above the texts containing the answer and rely on reading from there. In relation to queries, multi-level texts are used to extend hits with more detail or, occasionally, more context. Designers should consider how...

  16. Self-assembly of hierarchically ordered structures in DNA nanotube systems

    Science.gov (United States)

    Glaser, Martin; Schnauß, Jörg; Tschirner, Teresa; Schmidt, B. U. Sebastian; Moebius-Winkler, Maximilian; Käs, Josef A.; Smith, David M.

    2016-05-01

    The self-assembly of molecular and macromolecular building blocks into organized patterns is a complex process found in diverse systems over a wide range of size and time scales. The formation of star- or aster-like configurations, for example, is a common characteristic in solutions of polymers or other molecules containing multi-scaled, hierarchical assembly processes. This is a recurring phenomenon in numerous pattern-forming systems ranging from cellular constructs to solutions of ferromagnetic colloids or synthetic plastics. To date, however, it has not been possible to systematically parameterize structural properties of the constituent components in order to study their influence on assembled states. Here, we circumvent this limitation by using DNA nanotubes with programmable mechanical properties as our basic building blocks. A small set of DNA oligonucleotides can be chosen to hybridize into micron-length DNA nanotubes with a well-defined circumference and stiffness. The self-assembly of these nanotubes to hierarchically ordered structures is driven by depletion forces caused by the presence of polyethylene glycol. This trait allowed us to investigate self-assembly effects while maintaining a complete decoupling of density, self-association or bundling strength, and stiffness of the nanotubes. Our findings show diverse ranges of emerging structures including heterogeneous networks, aster-like structures, and densely bundled needle-like structures, which compare to configurations found in many other systems. These show a strong dependence not only on concentration and bundling strength, but also on the underlying mechanical properties of the nanotubes. Similar network architectures to those caused by depletion forces in the low-density regime are obtained when an alternative hybridization-based bundling mechanism is employed to induce self-assembly in an isotropic network of pre-formed DNA nanotubes. This emphasizes the universal effect inevitable

  17. Friction and adhesion of hierarchical carbon nanotube structures for biomimetic dry adhesives: multiscale modeling.

    Science.gov (United States)

    Hu, Shihao; Jiang, Haodan; Xia, Zhenhai; Gao, Xiaosheng

    2010-09-01

    With unique hierarchical fibrillar structures on their feet, gecko lizards can walk on vertical walls or even ceilings. Recent experiments have shown that strong binding along the shear direction and easy lifting in the normal direction can be achieved by forming unidirectional carbon nanotube array with laterally distributed tips similar to gecko's feet. In this study, a multiscale modeling approach was developed to analyze friction and adhesion behaviors of this hierarchical fibrillar system. Vertically aligned carbon nanotube array with laterally distributed segments at the end was simulated by coarse grained molecular dynamics. The effects of the laterally distributed segments on friction and adhesion strengths were analyzed, and further adopted as cohesive laws used in finite element analysis at device scale. The results show that the laterally distributed segments play an essential role in achieving high force anisotropy between normal and shear directions in the adhesives. Finite element analysis reveals a new friction-enhanced adhesion mechanism of the carbon nanotube array, which also exists in gecko adhesive system. The multiscale modeling provides an approach to bridge the microlevel structures of the carbon nanotube array with its macrolevel adhesive behaviors, and the predictions from this modeling give an insight into the mechanisms of gecko-mimicking dry adhesives.

  18. Emergence of hierarchical structure mirroring linguistic composition in a recurrent neural network.

    Science.gov (United States)

    Hinoshita, Wataru; Arie, Hiroaki; Tani, Jun; Okuno, Hiroshi G; Ogata, Tetsuya

    2011-05-01

    We show that a Multiple Timescale Recurrent Neural Network (MTRNN) can acquire the capabilities to recognize, generate, and correct sentences by self-organizing in a way that mirrors the hierarchical structure of sentences: characters grouped into words, and words into sentences. The model can control which sentence to generate depending on its initial states (generation phase) and the initial states can be calculated from the target sentence (recognition phase). In an experiment, we trained our model over a set of unannotated sentences from an artificial language, represented as sequences of characters. Once trained, the model could recognize and generate grammatical sentences, even if they were not learned. Moreover, we found that our model could correct a few substitution errors in a sentence, and the correction performance was improved by adding the errors to the training sentences in each training iteration with a certain probability. An analysis of the neural activations in our model revealed that the MTRNN had self-organized, reflecting the hierarchical linguistic structure by taking advantage of the differences in timescale among its neurons: in particular, neurons that change the fastest represented "characters", those that change more slowly, "words", and those that change the slowest, "sentences".

  19. Hierarchical structures induce long-range dynamical correlations in written texts.

    Science.gov (United States)

    Alvarez-Lacalle, E; Dorow, B; Eckmann, J-P; Moses, E

    2006-05-23

    Thoughts and ideas are multidimensional and often concurrent, yet they can be expressed surprisingly well sequentially by the translation into language. This reduction of dimensions occurs naturally but requires memory and necessitates the existence of correlations, e.g., in written text. However, correlations in word appearance decay quickly, while previous observations of long-range correlations using random walk approaches yield little insight on memory or on semantic context. Instead, we study combinations of words that a reader is exposed to within a "window of attention," spanning about 100 words. We define a vector space of such word combinations by looking at words that co-occur within the window of attention, and analyze its structure. Singular value decomposition of the co-occurrence matrix identifies a basis whose vectors correspond to specific topics, or "concepts" that are relevant to the text. As the reader follows a text, the "vector of attention" traces out a trajectory of directions in this "concept space." We find that memory of the direction is retained over long times, forming power-law correlations. The appearance of power laws hints at the existence of an underlying hierarchical network. Indeed, imposing a hierarchy similar to that defined by volumes, chapters, paragraphs, etc. succeeds in creating correlations in a surrogate random text that are identical to those of the original text. We conclude that hierarchical structures in text serve to create long-range correlations, and use the reader's memory in reenacting some of the multidimensionality of the thoughts being expressed.

  20. Hierarchical assemblies of soft matters from polymers and liquid crystals on structured surfaces

    Science.gov (United States)

    Honglawan, Apiradee

    Hierarchical, multifunctional materials hold important keys to numerous advanced technologies, including electronics, optics, and medicine. This thesis encompasses generation of hierarchical structures with novel morphologies and functions through self-assembly directed by lithographically fabricated templates. Here, two soft materials, amphiphilic random copolymers of photopolymerized acryloyl chloride (ranPAC) and smectic-A liquid crystal (SmA-LC) molecule, 4'(5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecaflu-orododecyloxy)-biphenyl-4-carboxylic acid ethyl ester, are synthesized as model systems to investigate the governing principles at the topographic surface/interface. The ranPAC can self-organize into nanomicelles with high regularity and stability, typically not possible in random copolymer systems. The morphology can be controlled by the photopolymerization conditions and solvent; the crosslinked shell makes the micelles robust against drying and storage. Using SU-8 micropillar arrays with spatially controlled surface chemistry as templates, we construct hierarchical microporous structures with tunable pore size and symmetry (e.g. square array), and uncover a new evaporative assembly method. By functionalizing the ranPAC nanovesicles with cationic poly(ethyleneimines), we encapsulate the anticancer drug, doxorubicin hydrochloride, and mRNA at a high payload, which are delivered to HEK 293T cells in vitro at a low cytotoxicity level. SmA-LC are characterized by arrangement of molecules into thin layers with the long molecular axis parallel to the layer normal, forming a close-packed hexagonal array of topological defects known as focal conic domains (FCDs) in a thin film. Using a series of SU-8 micropillar arrays with different size, shape, height, and symmetry as topological templates, we investigate the epitaxial and hierarchical assemblies of FCDs; whether the system favors confinement or "pillar edge-pinning" depends on balance of the elastic energy

  1. Hierarchical Structured Cu/Ni/TiO2 Nanocomposites as Electrodes for Lithium-Ion Batteries.

    Science.gov (United States)

    Yue, Yuan; Juarez-Robles, Daniel; Chen, Yan; Ma, Lian; Kuo, Winson C H; Mukherjee, Partha; Liang, Hong

    2017-08-30

    The electrochemical performance of anodes made of transition metal oxides (TMOs) in lithium-ion batteries (LIBs) often suffers from their chemical and mechanical instability. In this research, a novel electrode with a hierarchical current collector for TMO active materials is successfully fabricated. It consists of porous nickel as current collector on a copper substrate. The copper has vertically aligned microchannels. Anatase titanium dioxide (TiO2) nanoparticles of ∼100 nm are directly synthesized and cast on the porous Ni using a one-step process. Characterization indicates that this electrode exhibits excellent performance in terms of capacity, reliable rate, and long cyclic stability. The maximum insertion coefficient for the reaction product of LixTiO2 is ∼0.85, a desirable value as an anode of LIBs. Cross-sectional SEM and EDS analysis confirmed the uniform and stable distribution of nanosized TiO2 nanoparticles inside the Ni microchannels during cycling. This is due to the synergistic effect of nano-TiO2 and the hierarchical Cu/Ni current collector. The advantages of the Cu/Ni/TiO2 anode include enhanced activity of electrochemical reactions, shortened lithium ion diffusion pathways, ultrahigh specific surface area, effective accommodation of volume changes of TiO2 nanoparticles, and optimized routes for electrons transport.

  2. Hierarchically structured self-supported latex films for flexible and semi-transparent electronics

    Energy Technology Data Exchange (ETDEWEB)

    Määttänen, Anni, E-mail: anni.maattanen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Ihalainen, Petri, E-mail: petri.ihalainen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Törngren, Björn, E-mail: bjorn.torngren@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Rosqvist, Emil, E-mail: emil.rosqvist@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Pesonen, Markus, E-mail: markus.pesonen@abo.fi [Physics, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Peltonen, Jouko, E-mail: jouko.peltonen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland)

    2016-02-28

    Graphical abstract: - Highlights: • Transparent self-supported latex films were fabricated by a peel-off process. • Various template substrates were used for creating e.g. hierarchically structured latex films. • Ultra-thin and semi-transparent conductive gold electrodes were evaporated on the latex films.Electrochemical experiments were carried out to verify the applicability of the electrodes. - Abstract: Different length scale alterations in topography, surface texture, and symmetry are known to evoke diverse cell behavior, including adhesion, orientation, motility, cytoskeletal condensation, and modulation of intracellular signaling pathways. In this work, self-supported latex films with well-defined isotropic/anisotropic surface features and hierarchical morphologies were fabricated by a peel-off process from different template surfaces. In addition, the latex films were used as substrates for evaporated ultrathin gold films with nominal thicknesses of 10 and 20 nm. Optical properties and topography of the samples were characterized using UV–vis spectroscopy and Atomic Force Microscopy (AFM) measurements, respectively. The latex films showed high-level transmittance of visible light, enabling the fabrication of semi-transparent gold electrodes. Electrochemical impedance spectroscopy (EIS) measurements were carried out for a number of days to investigate the long-term stability of the electrodes. The effect of 1-octadecanethiol (ODT) and HS(CH{sub 2}){sub 11}OH (MuOH) thiolation and protein (human serum albumin, HSA) adsorption on the impedance and capacitance was studied. In addition, cyclic voltammetry (CV) measurements were carried out to determine active medicinal components, i.e., caffeic acid with interesting biological activities and poorly water-soluble anti-inflammatory drug, piroxicam. The results show that the fabrication procedure presented in this study enables the formation of platforms with hierarchical morphologies for multimodal

  3. Hierarchical Network Design

    DEFF Research Database (Denmark)

    Thomadsen, Tommy

    2005-01-01

    of different types of hierarchical networks. This is supplemented by a review of ring network design problems and a presentation of a model allowing for modeling most hierarchical networks. We use methods based on linear programming to design the hierarchical networks. Thus, a brief introduction to the various....... The thesis investigates models for hierarchical network design and methods used to design such networks. In addition, ring network design is considered, since ring networks commonly appear in the design of hierarchical networks. The thesis introduces hierarchical networks, including a classification scheme...... linear programming based methods is included. The thesis is thus suitable as a foundation for study of design of hierarchical networks. The major contribution of the thesis consists of seven papers which are included in the appendix. The papers address hierarchical network design and/or ring network...

  4. Structure, dynamics and evolution of disk galaxies in a hierarchical formation scenario

    CERN Document Server

    Firmani, C

    1999-01-01

    Using galaxy evolutionary models in a hierarchical formation scenario, we predict the structure, dynamics and evolution of disk galaxies in a LCDM universe. Our models include star formation and hydrodynamics of the ISM. We find that the Tully-Fisher relation (TFR) in the I and H bands is an imprint of the mass-velocity relation of the cosmological dark halos. The scatter of the TFR originates mainly from the scatter in the dark halo structure and, to a minor extension, from the dispersion of the primordial spin parameter lambda. Our models allow us to explain why low and high surface brightness galaxies have the same TFR. The disk gas fractions predicted agree with the observations. The disks formed within the growing halos have nearly exponential surface brightness and flat rotation curves. Towards high redshifts, the zero-point of the TFR in the H band increases while in the B-band it slightly decreases.

  5. Fischer-Tropsch synthesis on hierarchically structured cobalt nanoparticle/carbon nanofiber/carbon felt composites.

    Science.gov (United States)

    Zarubova, Sarka; Rane, Shreyas; Yang, Jia; Yu, Yingda; Zhu, Ye; Chen, De; Holmen, Anders

    2011-07-18

    The hierarchically structured carbon nanofibers (CNFs)/carbon felt composites, in which CNFs were directly grown on the surface of microfibers in carbon felt, forming a CNF layer on a micrometer range that completely covers the microfiber surfaces, were tested as a novel support material for cobalt nanoparticles in the highly exothermic Fischer-Tropsch (F-T) synthesis. A compact, fixed-bed reactor, made of disks of such composite materials, offered the advantages of improved heat and mass transfer, relatively low pressure drop, and safe handling of immobilized CNFs. An efficient 3-D thermal conductive network in the composite provided a relatively uniform temperature profile, whereas the open structure of the CNF layer afforded an almost 100 % effectiveness of Co nanoparticles in the F-T synthesis in the fixed bed. The greatly improved mass and heat transport makes the compact reactor attractive for applications in the conversion of biomass, coal, and natural gas to liquids.

  6. Exploring the hierarchical structure of the MMPI-2-RF Personality Psychopathology Five in psychiatric patient and university student samples.

    Science.gov (United States)

    Bagby, R Michael; Sellbom, Martin; Ayearst, Lindsay E; Chmielewski, Michael S; Anderson, Jaime L; Quilty, Lena C

    2014-01-01

    In this study our goal was to examine the hierarchical structure of personality pathology as conceptualized by Harkness and McNulty's (1994) Personality Psychopathology Five (PSY-5) model, as recently operationalized by the MMPI-2-RF (Ben-Porath & Tellegen, 2011) PSY-5r scales. We used Goldberg's (2006) "bass-ackwards" method to obtain factor structure using PSY-5r item data, successively extracting from 1 to 5 factors in a sample of psychiatric patients (n = 1,000) and a sample of university undergraduate students (n = 1,331). Participants from these samples had completed either the MMPI-2 or the MMPI-2-RF. The results were mostly consistent across the 2 samples, with some differences at the 3-factor level. In the patient sample a factor structure representing 3 broad psychopathology domains (internalizing, externalizing, and psychoticism) emerged; in the student sample the 3-factor level represented what is more commonly observed in "normal-range" personality models (negative emotionality, introversion, and disconstraint). At the 5-factor level the basic structure was similar across the 2 samples and represented well the PSY-5r domains.

  7. A neural signature of hierarchical reinforcement learning.

    Science.gov (United States)

    Ribas-Fernandes, José J F; Solway, Alec; Diuk, Carlos; McGuire, Joseph T; Barto, Andrew G; Niv, Yael; Botvinick, Matthew M

    2011-07-28

    Human behavior displays hierarchical structure: simple actions cohere into subtask sequences, which work together to accomplish overall task goals. Although the neural substrates of such hierarchy have been the target of increasing research, they remain poorly understood. We propose that the computations supporting hierarchical behavior may relate to those in hierarchical reinforcement learning (HRL), a machine-learning framework that extends reinforcement-learning mechanisms into hierarchical domains. To test this, we leveraged a distinctive prediction arising from HRL. In ordinary reinforcement learning, reward prediction errors are computed when there is an unanticipated change in the prospects for accomplishing overall task goals. HRL entails that prediction errors should also occur in relation to task subgoals. In three neuroimaging studies we observed neural responses consistent with such subgoal-related reward prediction errors, within structures previously implicated in reinforcement learning. The results reported support the relevance of HRL to the neural processes underlying hierarchical behavior.

  8. Asymmetric flexural behavior from bamboo's functionally graded hierarchical structure: underlying mechanisms.

    Science.gov (United States)

    Habibi, Meisam K; Samaei, Arash T; Gheshlaghi, Behnam; Lu, Jian; Lu, Yang

    2015-04-01

    As one of the most renewable resources on Earth, bamboo has recently attracted increasing interest for its promising applications in sustainable structural purposes. Its superior mechanical properties arising from the unique functionally-graded (FG) hierarchical structure also make bamboo an excellent candidate for bio-mimicking purposes in advanced material design. However, despite its well-documented, impressive mechanical characteristics, the intriguing asymmetry in flexural behavior of bamboo, alongside its underlying mechanisms, has not yet been fully understood. Here, we used multi-scale mechanical characterizations assisted with advanced environmental scanning electron microscopy (ESEM) to investigate the asymmetric flexural responses of natural bamboo (Phyllostachys edulis) strips under different loading configurations, during "elastic bending" and "fracture failure" stages, with their respective deformation mechanisms at microstructural level. Results showed that the gradient distribution of the vascular bundles along the thickness direction is mainly responsible for the exhibited asymmetry, whereas the hierarchical fiber/parenchyma cellular structure plays a critical role in alternating the dominant factors for determining the distinctly different failure mechanisms. A numerical model has been likewise adopted to validate the effective flexural moduli of bamboo strips as a function of their FG parameters, while additional experiments on uniaxial loading of bamboo specimens were performed to assess the tension-compression asymmetry, for further understanding of the microstructure evolution of bamboo's outer and innermost layers under different bending states. This work could provide insights to help the processing of novel bamboo-based composites and enable the bio-inspired design of advanced structural materials with desired flexural behavior.

  9. The porous carbon derived from water hyacinth with well-designed hierarchical structure for supercapacitors

    Science.gov (United States)

    Zheng, Kaiwen; Li, Yuanyuan; Zhu, Ming; Yu, Xi; Zhang, Mengyan; Shi, Ling; Cheng, Jue

    2017-10-01

    A hierarchical porous water hyacinth-derived carbon (WHC) is fabricated by pre-carbonization and KOH activation for supercapacitors. The physicochemical properties of WHC are researched by scanning electron microscopy (SEM), N2 adsorption-desorption measurements, X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results indicate that WHC exhibits hierarchical porous structure and high specific surface area of 2276 m2/g. And the electrochemical properties of WHC are studied by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) tests. In a three-electrode test system, WHC shows considerable specific capacitance of 344.9 F/g at a current density of 0.5 A/g, good rate performance with 225.8 F/g even at a current density of 30 A/g, and good cycle stability with 95% of the capacitance retention after 10000 cycles of charge-discharge at a current density of 5 A/g. Moreover, WHC cell delivers an energy density of 23.8 Wh/kg at 0.5 A/g and a power density of 15.7 kW/kg at 10 A/g. Thus, using water hyacinth as carbon source to fabricate supercapacitors electrodes is a promising approach for developing inexpensive, sustainable and high-performance carbon materials. Additionally, this study supports the sustainable development and the control of biological invasion.

  10. Highly Stretchable Superhydrophobic Composite Coating Based on Self-Adaptive Deformation of Hierarchical Structures.

    Science.gov (United States)

    Hu, Xin; Tang, Changyu; He, Zhoukun; Shao, Hong; Xu, Keqin; Mei, Jun; Lau, Woon-Ming

    2017-05-01

    With the rapid development of stretchable electronics, functional textiles, and flexible sensors, water-proof protection materials are required to be built on various highly flexible substrates. However, maintaining the antiwetting of superhydrophobic surface under stretching is still a big challenge since the hierarchical structures at hybridized micro-nanoscales are easily damaged following large deformation of the substrates. This study reports a highly stretchable and mechanically stable superhydrophobic surface prepared by a facile spray coating of carbon black/polybutadiene elastomeric composite on a rubber substrate followed by thermal curing. The resulting composite coating can maintain its superhydrophobic property (water contact angle ≈170° and sliding angle superhydrophobic property. Furthermore, the experimental observation and modeling analysis reveal that the stable superhydrophobic properties of the composite coating are attributed to the unique self-adaptive deformation ability of 3D hierarchical roughness of the composite coating, which delays the Cassie-Wenzel transition of surface wetting. In addition, it is first observed that the damaged coating can automatically recover its superhydrophobicity via a simple stretching treatment without incorporating additional hydrophobic materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Construct validity of the WISC-IV with a referred sample: direct versus indirect hierarchical structures.

    Science.gov (United States)

    Canivez, Gary L

    2014-03-01

    The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) is one of the most frequently used intelligence tests in clinical assessments of children with learning difficulties. Construct validity studies of the WISC-IV have generally supported the higher order structure with four correlated first-order factors and one higher-order general intelligence factor, but recent studies have supported an alternate model in which general intelligence is conceptualized as a breadth factor rather than a superordinate factor (M. W. Watkins, 2010, Structure of the Wechsler Intelligence Scale for Children-Fourth Edition among a national sample of referred students, Psychological Assessment, Vol. 22, pp. 782-787; M. W. Watkins, G. L. Canivez, T. James, K. & R. Good, in press, Construct validity of the WISC-IVUK with a large referred Irish sample, International Journal of School and Educational Psychology). WISC-IV core subtest data obtained from evaluations to assess learning difficulties in 345 children (224 boys, 121 girls) were examined. One through four, first order factor models and indirect versus direct hierarchical models were compared using confirmatory factor analyses. The correlated four-factor Wechsler model provided good fit to these data, but the direct hierarchical model showed statistically significant improvement over the indirect hierarchical model and correlated four-factor model. The direct hierarchical model was judged the best explanation of the WISC-IV factor structure, with the general factor accounting for 71.6% of the common variance while the first order factors accounted for 2.4-10.3% of the common variance. Thus, the results with the present sample of referred children were similar to those from other investigations (G. E. Gignac, 2005, Revisiting the factor structure of the WAIS-R: Insights through nested factor modeling, Assessment, Vol. 12, pp. 320-329; G. E. Gignac, 2006, The WAIS-III as a nested factors model: A useful alternative to

  12. Light-Emitting Diodes with Hierarchical and Multifunctional Surface Structures for High Light Extraction and an Antifouling Effect.

    Science.gov (United States)

    Leem, Young-Chul; Park, Jung Su; Kim, Joon Heon; Myoung, NoSoung; Yim, Sang-Youp; Jeong, Sehee; Lim, Wantae; Kim, Sung-Tae; Park, Seong-Ju

    2016-01-13

    Bioinspired hierarchical structures on the surface of vertical light-emitting diodes (VLEDs) are demonstrated by combining a self-assembled dip-coating process and nanopatterning transfer method using thermal release tape. This versatile surface structure can efficiently reduce the total internal reflection and add functions, such as superhydrophobicity and high oleophobicity, to achieve an antifouling effect for VLEDs.

  13. Determination of genetic structure of germplasm collections: are traditional hierarchical clustering methods appropriate for molecular marker data?

    Science.gov (United States)

    Odong, T L; van Heerwaarden, J; Jansen, J; van Hintum, T J L; van Eeuwijk, F A

    2011-07-01

    Despite the availability of newer approaches, traditional hierarchical clustering remains very popular in genetic diversity studies in plants. However, little is known about its suitability for molecular marker data. We studied the performance of traditional hierarchical clustering techniques using real and simulated molecular marker data. Our study also compared the performance of traditional hierarchical clustering with model-based clustering (STRUCTURE). We showed that the cophenetic correlation coefficient is directly related to subgroup differentiation and can thus be used as an indicator of the presence of genetically distinct subgroups in germplasm collections. Whereas UPGMA performed well in preserving distances between accessions, Ward excelled in recovering groups. Our results also showed a close similarity between clusters obtained by Ward and by STRUCTURE. Traditional cluster analysis can provide an easy and effective way of determining structure in germplasm collections using molecular marker data, and, the output can be used for sampling core collections or for association studies.

  14. Self-similar Hierarchical Wrinkles as a Potential Multifunctional Smart Window with Simultaneously Tunable Transparency, Structural Color, and Droplet Transport.

    Science.gov (United States)

    Lin, Gaojian; Chandrasekaran, Prashant; Lv, Cunjing; Zhang, Qiuting; Tang, Yichao; Han, Lin; Yin, Jie

    2017-08-09

    Smart window has immense potential for energy savings in architectural and vehicular applications, while most studies focus on the tunability of a single property of optical transmittance. Here we explore harnessing dynamically tunable hierarchical wrinkles for design of a potential multifunctional smart window with combined structural color and water droplet transport control. The self-similar hierarchical wrinkles with both nanoscale and microscale features are generated on a prestrained poly(dimethylsiloxane) elastomer through sequential strain release and multistep oxygen plasma treatment. We show that the hierarchically wrinkled elastomer displays both opaqueness and iridescent structural color. We find that restretching/releasing the elastomer leads to the reversible and repeatable switch from opaqueness to transparency, arising from the flattening of large wrinkles (micrometer scale), while a nonvanishing structural color occurs due to the nondisappearing small wrinkles (nanoscale). The unique features of combined reversible large wrinkles and irreversible small wrinkles during hierarchical wrinkling are well reproduced by corresponding finite element simulation. The criteria for generating self-similar hierarchical wrinkles is revealed through a simplified theoretical model and validated by experiments. In addition to its tunable optical property, we further show its ability in control of water droplet transport on demand through mechanical stretching and release. We find that an initially pinned water droplet on the tilted hierarchically wrinkled surface starts to slide when the surface is stretched, and becomes pinned again upon strain release. Such a process is reversible and repeatable. The hierarchically wrinkled surface could find broad potential applications not only in multifunctional smart windows with additional features of aesthetics and water collection, but in microfluidics, design of slippery surfaces, and directional water transportation.

  15. Multiscale mechanics of hierarchical structure/property relationships in calcified tissues and tissue/material interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Katz, J. Lawrence [School of Computing and Engineering, University of Missouri-Kansas City, Kansas City, MO (United States) and School of Dentistry, University of Missouri-Kansas City, Kansas City, MO (United States)]. E-mail: katzjl@umkc.edu; Misra, Anil [School of Computing and Engineering, University of Missouri-Kansas City, Kansas City, MO (United States); Spencer, Paulette [School of Dentistry, University of Missouri-Kansas City, Kansas City, MO (United States); Wang, Yong [School of Dentistry, University of Missouri-Kansas City, Kansas City, MO (United States); Bumrerraj, Sauwanan [School of Medicine, Khon Kaen University, Khon Kaen (Thailand); Nomura, Tsutomu [School of Dentistry, Niigata University, Niigata (Japan); Eppell, Steven J. [Case School of Engineering, Case Western Reserve University, Cleveland, OH (United States); Tabib-Azar, Massood [Case School of Engineering, Case Western Reserve University, Cleveland, OH (United States)

    2007-04-15

    This paper presents a review plus new data that describes the role hierarchical nanostructural properties play in developing an understanding of the effect of scale on the material properties (chemical, elastic and electrical) of calcified tissues as well as the interfaces that form between such tissues and biomaterials. Both nanostructural and microstructural properties will be considered starting with the size and shape of the apatitic mineralites in both young and mature bovine bone. Microstructural properties for human dentin and cortical and trabecular bone will be considered. These separate sets of data will be combined mathematically to advance the effects of scale on the modeling of these tissues and the tissue/biomaterial interfaces as hierarchical material/structural composites. Interfacial structure and properties to be considered in greatest detail will be that of the dentin/adhesive (d/a) interface, which presents a clear example of examining all three material properties, (chemical, elastic and electrical). In this case, finite element modeling (FEA) was based on the actual measured values of the structure and elastic properties of the materials comprising the d/a interface; this combination provides insight into factors and mechanisms that contribute to premature failure of dental composite fillings. At present, there are more elastic property data obtained by microstructural measurements, especially high frequency ultrasonic wave propagation (UWP) and scanning acoustic microscopy (SAM) techniques. However, atomic force microscopy (AFM) and nanoindentation (NI) of cortical and trabecular bone and the dentin-enamel junction (DEJ) among others have become available allowing correlation of the nanostructural level measurements with those made on the microstructural level.

  16. Mechanics of robust and releasable adhesion in biology: Bottom up designed hierarchical structures of gecko

    Science.gov (United States)

    Yao, Haimin; Gao, Huajian

    2006-06-01

    Gecko and many insects have evolved specialized adhesive tissues with bottom-up designed (from nanoscale and up) hierarchical structures that allow them to maneuver on vertical walls and ceilings. The adhesion mechanisms of gecko must be robust enough to function on unknown rough surfaces and also easily releasable upon animal movement. How does nature design such macroscopic sized robust and releasable adhesion devices? How can an adhesion system designed for robust attachment simultaneously allow easy detachment? These questions have motivated the present investigation on mechanics of robust and releasable adhesion in biology. On the question of robust adhesion, we introduce a fractal gecko hairs model, which assumes self-similar fibrillar structures at multiple hierarchical levels mimicking gecko's spatula ultrastructure, to show that structural hierarchy plays a key role in robust adhesion: it allows the work of adhesion to be exponentially enhanced with each added level of hierarchy. We demonstrate that, barring fiber fracture, the fractal gecko hairs can be designed from nanoscale and up to achieve flaw tolerant adhesion at any length scales. However, consideration of crack-like flaws in the hairs themselves results in an upper size limit for flaw tolerant design. On the question of releasable adhesion, we hypothesize that the asymmetrically aligned seta hairs of gecko form a strongly anisotropic material with adhesion strength strongly varying with the direction of pulling. We use analytical solutions to show that a strongly anisotropic elastic solid indeed exhibits a strongly anisotropic adhesion strength when sticking on a rough surface. Furthermore, we perform finite element calculations to show that the adhesion strength of a strongly anisotropic attachment pad exhibits essentially two levels of adhesion strength depending on the direction of pulling, resulting in an orientation-controlled switch between attachment and detachment. These findings not only

  17. Hierarchical composite structures prepared by electrophoretic deposition of carbon nanotubes onto glass fibers.

    Science.gov (United States)

    An, Qi; Rider, Andrew N; Thostenson, Erik T

    2013-03-01

    Carbon nanotube/glass fiber hierarchical composite structures have been produced using an electrophoretic deposition (EPD) approach for integrating the carbon nanotubes (CNTs) into unidirectional E-glass fabric, followed by infusion of an epoxy polymer matrix. The resulting composites show a hierarchical structure, where the structural glass fibers, which have diameters in micrometer range, are coated with CNTs having diameters around 10-20 nm. The stable aqueous dispersions of CNTs were produced using a novel ozonolysis and ultrasonication technique that results in dispersion and functionalization in a single step. Ozone-oxidized CNTs were then chemically reacted with a polyethyleneimine (PEI) dendrimer to enable cathodic EPD and promote adhesion between the CNTs and the glass-fiber substrate. Deposition onto the fabric was accomplished by placing the fabric in front of the cathode and applying a direct current (DC) field. Microscopic characterization shows the integration of CNTs throughout the thickness of the glass fabric, where individual fibers are coated with CNTs and a thin film of CNTs also forms on the fabric surfaces. Within the composite, networks of CNTs span between adjacent fibers, and the resulting composites exhibit good electrical conductivity and considerable increases in the interlaminar shear strength, relative to fiber composites without integrated CNTs. Mechanical, chemical and morphological characterization of the coated fiber surfaces reveal interface/interphase modification resulting from the coating is responsible for the improved mechanical and electrical properties. The CNT-coated glass-fiber laminates also exhibited clear changes in electrical resistance as a function of applied shear strain and enables self-sensing of the transition between elastic and plastic load regions.

  18. Active Antifogging Property of Monolayer SiO2 Film with Bioinspired Multiscale Hierarchical Pagoda Structures.

    Science.gov (United States)

    Han, Zhiwu; Mu, Zhengzhi; Li, Bo; Wang, Ze; Zhang, Junqiu; Niu, Shichao; Ren, Luquan

    2016-09-27

    Antifogging surfaces with hydrophilic or even superhydrophilic wetting behavior have received significant attention due to their ability to reduce light scattering by film-like condensation. However, a major challenge remains in achieving high-speed antifogging performance and revealing the hydrophilic-based antifogging mechanism of glass or other transparent materials under aggressive fogging conditions. Herein, with inspiration from the fog-free property of the typical Morpho menelaus terrestris butterfly (Butler, 1866) wing scales, a monolayer SiO2 film with multiscale hierarchical pagoda structures (MHPSs) based on glass substrate was designed and fabricated using an optimized biotemplate-assisted wet chemical method without any post-treatments. The biomimetic monolayer film (BMF) composed of nanoscale SiO2 3D networks displayed excellent antifogging properties, which is superior to that of the glass substrate itself. The MHPS-based BMF even kept high transmittance (∼95%) under aggressive fog conditions, and it almost instantaneously recovered to a fog-free state (properties mainly benefit from the synergistic effect of both hydrophilic chemical compositions (nanoscale SiO2) and physical structures (biomimetic MHPSs) of the BMF. High-speed active antifogging performance of the glass materials enabled the retention of a high transmittance property even in humid conditions, heralding reliable optical performance in outdoor practical applications, especially in aggressive foggy environments. More importantly, the investigations in this work offer a promising way to handily design and fabricate quasi-textured surfaces with multiscale hierarchical structures that possess high-performance physicochemical properties.

  19. The relationship between carbon dioxide emission and economic growth: Hierarchical structure methods

    Science.gov (United States)

    Deviren, Seyma Akkaya; Deviren, Bayram

    2016-06-01

    Carbon dioxide (CO2) emission has an essential role in the current debate on sustainable development and environmental protection. CO2 emission is also directly linked with use of energy which plays a focal role both for production and consumption in the world economy. Therefore the relationship between the CO2 emission and economic growth has a significant implication for the environmental and economical policies. In this study, within the scope of sociophysics, the topology, taxonomy and relationships among the 33 countries, which have almost the high CO2 emission and economic growth values, are investigated by using the hierarchical structure methods, such as the minimal spanning tree (MST) and hierarchical tree (HT), over the period of 1970-2010. The average linkage cluster analysis (ALCA) is also used to examine the cluster structure more clearly in HTs. According to their proximity, economic ties and economic growth, different clusters of countries are identified from the structural topologies of these trees. We have found that the high income & OECD countries are closely connected to each other and are isolated from the upper middle and lower middle income countries from the MSTs, which are obtained both for the CO2 emission and economic growth. Moreover, the high income & OECD clusters are homogeneous with respect to the economic activities and economic ties of the countries. It is also mentioned that the Group of Seven (G7) countries (CAN, ENG, FRA, GER, ITA, JPN, USA) are connected to each other and these countries are located at the center of the MST for the results of CO2 emission. The same analysis may also successfully apply to the other environmental sources and different countries.

  20. Hierarchical columnar silicon anode structures for high energy density lithium sulfur batteries

    Science.gov (United States)

    Piwko, Markus; Kuntze, Thomas; Winkler, Sebastian; Straach, Steffen; Härtel, Paul; Althues, Holger; Kaskel, Stefan

    2017-05-01

    Silicon is a promising anode material for next generation lithium secondary batteries. To significantly increase the energy density of state of the art batteries with silicon, new concepts have to be developed and electrode structuring will become a key technology. Structuring is essential to reduce the macroscopic and microscopic electrode deformation, caused by the volume change during cycling. We report pulsed laser structuring for the generation of hierarchical columnar silicon films with outstanding high areal capacities up to 7.5 mAh cm-2 and good capacity retention. Unstructured columnar electrodes form a micron-sized block structure during the first cycle to compensate the volume expansion leading to macroscopic electrode deformation. At increased silicon loading, without additional structuring, pronounced distortion and the formation of cracks through the current collector causes cell failure. Pulsed laser ablation instead is demonstrated to avoid macroscopic electrode deformation by initial formation of the block structure. A full cell with lithiated silicon versus a carbon-sulfur cathode is assembled with only 15% overbalanced anode and low electrolyte amount (8 μl mgsulfur-1). While the capacity retention over 50 cycles is identical to a cell with high excess lithium anode, the volumetric energy density could be increased by 30%.

  1. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Nozaki, Kosuke [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Shinonaga, Togo [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Tsukamoto, Masahiro [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Yamashita, Kimihiro [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Nagai, Akiko, E-mail: nag-bcr@tmd.ac.jp [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan)

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni–Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol. - Highlights: • Hierarchical micro/nano-structures were created on nitinol using a femtosecond laser. • The nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. • Endothelial cells aligned along the nano-structures • Platelets failed to adhere to the micro/nano-surface.

  2. One-step self-assembled synthesis of CuO with tunable hierarchical structures and their electrocatalytic properties for nitrite oxidation in aqueous media.

    Science.gov (United States)

    Zhao, Youcheng; Song, Xinyu; Yin, Zhilei; Song, Qisheng

    2013-04-15

    Controlled synthesis of CuO with various hierarchical structures consisting of self-organized nanoparticles is realized by using n-octylamine (OLA) as a structure inducing agent via a facile hydrothermal synthetic method. The growth and assemblage of CuO can be finely tuned by selecting the preparative parameters. In particular, it is found that the degree of the hierarchical organization can be modulated by simply changing the amount of the n-octylamine and CuO nanoparticles exhibit self-assembled two-dimensional (2D) sheet-like, three-dimensional (3D) disk-like and bowknot-like architectures, respectively. In the present case, OLA serves as a capping surfactant that can modulate growth of CuO nanocrystals via hydrophobic forces between the OLA molecules. CuO nanoparticles can be self-assembled into different complex architectures depending on the strength of hydrophobic forces. Hierarchical sphere-like CuO assembled from nanorods can also be easily fabricated by adjusting the starting NaOH to CuCl2 volume ratio, in which OLA serves not only as the structure-directing agent, but also as a weak base agent to produce hydroxyl anions. The electrochemical performances of the as-synthesized different products for sensing nitrite oxidation are evaluated. The results reveal that the electrocatalytic activity is related to the secondary nanostructures. Compared to the others, the bowknot-shaped and sphere-shaped CuO products exhibit excellent electrocatalytic activity toward nitrite oxidation and fast current response in nitrite sensing because of their peculiar hierarchical structures with high BET surface areas and well-ordered pores.

  3. Hierarchically porous Ni monolith@branch-structured NiCo2O4 for high energy density supercapacitors

    Institute of Scientific and Technical Information of China (English)

    Mengjie Xu; Rongjun Xu; Ying Zhao; Libao Chen; Boyun Huang; Weifeng Wei n

    2016-01-01

    A variety of NiCo2O4 nanostrucutures ranging from nanowire to nanoplate and branched structures were successfully prepared via a simple hydrothermal process. The experimental results show that NiCo2O4 with branched structures possesses the best overall electrochemical performance. The improvement of energy density was explored in terms of hierarchically three-dimensional (3D) metal substrates and a high specific area capacitance, and area energy density is obtained with hierarchically porous Ni monolith synthesized through a controlled combustion procedure.

  4. Hierarchically porous Ni monolith@branch-structured NiCo2O4 for high energy density supercapacitors

    Directory of Open Access Journals (Sweden)

    Mengjie Xu

    2016-06-01

    Full Text Available A variety of NiCo2O4 nanostrucutures ranging from nanowire to nanoplate and branched structures were successfully prepared via a simple hydrothermal process. The experimental results show that NiCo2O4 with branched structures possesses the best overall electrochemical performance. The improvement of energy density was explored in terms of hierarchically three-dimensional (3D metal substrates and a high specific area capacitance, and area energy density is obtained with hierarchically porous Ni monolith synthesized through a controlled combustion procedure.

  5. Multicast Address Management and Connection Control Based on Hierarchical Autonomous Structure

    Institute of Scientific and Technical Information of China (English)

    WANG Jian; ZHANG Fuyan

    1999-01-01

    Multicast capability, including multicast address and multicast routing mechanisms, at the network layeris necessary in order to reduce the bandwidth requirements of multiparty, multicast applications. Based on hierarchical autonomous structure in accordance with the self-organization topologies of Internet, the paper puts forward a multicast address management scheme that is shown to be robust and scalable. Connection control hierarchy (CCH) based on master/slave relationship and a simple efficient building algorithm of multi-point connection is also built. The paper also describes the normal operations of multicast address management andmulti-point connection controller. Through simulation experiment, HAM, CM and DDM of Multicast Address Allocation are compared. HAM integrates the merits of CM and DDM, which is efficient as a whole, robust andscalable. CCH raises the efficiency of connection control, and is highly robust, flexible and scalable.

  6. Hierarchical structured TiO2 photoanodes for dye-sensitized solar cells.

    Science.gov (United States)

    Shih, Yen-Chen; Chu, Ann-Kuo; Huang, Wen-Yao

    2012-04-01

    A novel approach has been developed to fabricate hills-like hierarchical structured TiO2 photoanodes for dye-sensitized solar cells (DSSCs). The appropriately aggregated TiO2 clusters in the photoanode layer could cause stronger light scattering and higher dye loading that increases the efficiency of photovoltaic device. For detailed light-harvesting study, different molecular weights of polyvinyl alcohol (PVA) were used as binders for TiO2 nanoparticles (P-25 Degussa) aggregation. A series of TiO2 films with dissimilar morphology, the reflection of TiO2 films, absorbance of attached dye, amount of dye loading, and performance of fabricated DSSC devices, were measured and investigated. An optimized device had energy conversion efficiency of 4.47% having a higher dye loading and good light harvesting, achieving a 23% increase of short-circuit current J(sc) in DSSCs.

  7. Identifying rock blocks based on hierarchical rock-mass structure model

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Rock-masses are divided into many closed blocks by deterministic and stochastic discontinuities and engineering interfaces in complex rock-mass engineering. Determining the sizes, shapes, and adjacent relations of blocks is important for stability analysis of fractured rock masses. Here we propose an algorithm for identifying spatial blocks based on a hierarchical 3D Rock-mass Structure Model (RSM). First, a model is built composed of deterministic discontinuities, engineering interfaces, and the earth’s surface, and the deterministic blocks surrounded by these interfaces are traced. Then, in each deter-ministic block, a network model of stochastic discontinuities is built and the stochastic blocks are traced. Building a unitary wire frame that connects all interfaces seamlessly is the key for our algorithm to identify the above two kinds of blocks. Using this algorithm, geometric models can be built for block theory, discrete element method, and discontinuous deformation analysis.

  8. Synthesis and properties of flexible nanocable with carbon nanotube @ polymer hierarchical structure

    Science.gov (United States)

    Ren, Junwen; Wang, Xiaoguang; Narayan Ramasubramanian, Lakshmi; Dong, Chengye; Cheng, Yonghong; Yu, Demei; Shan, Zhiwei

    2017-03-01

    A multi-functional polymer–carbon nanotube (CNT) nanocable with a hierarchical structure is fabricated by grafting poly (glycidyl methacrylate) (PGMA) from the CNT surface via activators regenerated by electron transfer atom transfer radical polymerization. Multiple CNTs are arranged in parallel in the fabricated nanocable and exhibit strong binding force with sheathing PGMA. In situ mechanical and electrical tests conducted on an individual nanocable reveal its high flexibility and excellent surface insulation, with an electrical resistance of approximately 1 GΩ. On increasing the voltage to the nanocable’s electrical breakdown point, nanoscale electrical trees are observed. Such degradation behavior is discussed in the wider context of breakdown mechanisms in polymer based CNTs.

  9. Hierarchically structured ZnO-graphene hollow microspheres towards effective reusable adsorbent for organic pollutant via photodegradation process

    Energy Technology Data Exchange (ETDEWEB)

    Bera, Susanta; Pal, Moumita; Naskar, Atanu; Jana, Sunirmal, E-mail: sjana@cgcri.res.in

    2016-06-05

    Present work reports on successful synthesis of hierarchical hollow microspheres (HHM) from ZnO-chemically converted graphene (CCG) nanocomposites by adopting low-temperature surfactant/template free solution method, varying graphene oxide (GO) to zinc acetate dihydrate weight ratio (R = 0.00, 0.01, 0.032, 0.063) in the precursors. It is found that the HHM consist of self-assembled ZnO nanoparticles, chemically interacted with CCG as evidenced from structural characterizations (X-ray diffraction, field emission scanning and transmission electron microscopes) with UV–Vis, FTIR, Raman and X-ray photoelectron spectroscopies. Multipoint BET nitrogen adsorption–desorption isotherms of ZG30, synthesized using an optimum GO content (R = 0.032) showed relatively high specific surface area. The sample showed significantly improved adsorption capacity of rhodamine B dye (as water pollutant) compare to pristine ZnO (R = 0.0) as well as commercially available P25 (TiO{sub 2}). The ZG30 functioned as reusable adsorbent due to its highly efficient photocatalytic activity under UV (λ, 254 nm) irradiation. Methyl orange and phenol were also used to check the effectiveness of ZG30 for permanent cleaning of the pollutants. This facile process could create an avenue for synthesis of hollow microspheres from different metal oxide semiconductor–graphene nanocomposites for efficient and reusable adsorbent of water soluble organic pollutants. - Graphical abstract: Hierarchical hollow microspheres from ZnO-graphene nanocomposites as reusable adsorbent of organic water pollutant. - Highlights: • Prepared hollow microspheres of ZnO-graphene nanocomposite (ZG) by solution route. • By optimizing graphene content, ZG shows improved adsorption capacity of dyes. • ZG shows a highly efficient photocatalytic activity of the dye pollutants. • It acts as a reusable adsorbent of the pollutants.

  10. A hierarchical model for structure learning based on the physiological characteristics of neurons

    Institute of Scientific and Technical Information of China (English)

    WEI Hui

    2007-01-01

    Almost all applications of Artificial Neural Networks (ANNs) depend mainly on their memory ability.The characteristics of typical ANN models are fixed connections,with evolved weights,globalized representations,and globalized optimizations,all based on a mathematical approach.This makes those models to be deficient in robustness,efficiency of learning,capacity,anti-jamming between training sets,and correlativity of samples,etc.In this paper,we attempt to address these problems by adopting the characteristics of biological neurons in morphology and signal processing.A hierarchical neural network was designed and realized to implement structure learning and representations based on connected structures.The basic characteristics of this model are localized and random connections,field limitations of neuron fan-in and fan-out,dynamic behavior of neurons,and samples represented through different sub-circuits of neurons specialized into different response patterns.At the end of this paper,some important aspects of error correction,capacity,learning efficiency,and soundness of structural representation are analyzed theoretically.This paper has demonstrated the feasibility and advantages of structure learning and representation.This model can serve as a fundamental element of cognitive systems such as perception and associative memory.Key-words structure learning,representation,associative memory,computational neuroscience

  11. Structural system identification using degree of freedom-based reduction and hierarchical clustering algorithm

    Science.gov (United States)

    Chang, Seongmin; Baek, Sungmin; Kim, Ki-Ook; Cho, Maenghyo

    2015-06-01

    A system identification method has been proposed to validate finite element models of complex structures using measured modal data. Finite element method is used for the system identification as well as the structural analysis. In perturbation methods, the perturbed system is expressed as a combination of the baseline structure and the related perturbations. The changes in dynamic responses are applied to determine the structural modifications so that the equilibrium may be satisfied in the perturbed system. In practical applications, the dynamic measurements are carried out on a limited number of accessible nodes and associated degrees of freedom. The equilibrium equation is, in principle, expressed in terms of the measured (master, primary) and unmeasured (slave, secondary) degrees of freedom. Only the specified degrees of freedom are included in the equation formulation for identification and the unspecified degrees of freedom are eliminated through the iterative improved reduction scheme. A large number of system parameters are included as the unknown variables in the system identification of large-scaled structures. The identification problem with large number of system parameters requires a large amount of computation time and resources. In the present study, a hierarchical clustering algorithm is applied to reduce the number of system parameters effectively. Numerical examples demonstrate that the proposed method greatly improves the accuracy and efficiency in the inverse problem of identification.

  12. Structure function relationship in complex brain networks expressed by hierarchical synchronization

    Science.gov (United States)

    Zhou, Changsong; Zemanová, Lucia; Zamora-López, Gorka; Hilgetag, Claus C.; Kurths, Jürgen

    2007-06-01

    The brain is one of the most complex systems in nature, with a structured complex connectivity. Recently, large-scale corticocortical connectivities, both structural and functional, have received a great deal of research attention, especially using the approach of complex network analysis. Understanding the relationship between structural and functional connectivity is of crucial importance in neuroscience. Here we try to illuminate this relationship by studying synchronization dynamics in a realistic anatomical network of cat cortical connectivity. We model the nodes (cortical areas) by a neural mass model (population model) or by a subnetwork of interacting excitable neurons (multilevel model). We show that if the dynamics is characterized by well-defined oscillations (neural mass model and subnetworks with strong couplings), the synchronization patterns are mainly determined by the node intensity (total input strengths of a node) and the detailed network topology is rather irrelevant. On the other hand, the multilevel model with weak couplings displays more irregular, biologically plausible dynamics, and the synchronization patterns reveal a hierarchical cluster organization in the network structure. The relationship between structural and functional connectivity at different levels of synchronization is explored. Thus, the study of synchronization in a multilevel complex network model of cortex can provide insights into the relationship between network topology and functional organization of complex brain networks.

  13. Time-domain analysis of neural tracking of hierarchical linguistic structures.

    Science.gov (United States)

    Zhang, Wen; Ding, Nai

    2017-02-01

    When listening to continuous speech, cortical activity measured by MEG concurrently follows the rhythms of multiple linguistic structures, e.g., syllables, phrases, and sentences. This phenomenon was previously characterized in the frequency domain. Here, we investigate the waveform of neural activity tracking linguistic structures in the time domain and quantify the coherence of neural response phases over subjects listening to the same stimulus. These analyses are achieved by decomposing the multi-channel MEG recordings into components that maximize the correlation between neural response waveforms across listeners. Each MEG component can be viewed as the recording from a virtual sensor that is spatially tuned to a cortical network showing coherent neural activity over subjects. This analysis reveals information not available from previous frequency-domain analysis of MEG global field power: First, concurrent neural tracking of hierarchical linguistic structures emerges at the beginning of the stimulus, rather than slowly building up after repetitions of the same sentential structure. Second, neural tracking of the sentential structure is reflected by slow neural fluctuations, rather than, e.g., a series of short-lasting transient responses at sentential boundaries. Lastly and most importantly, it shows that the MEG responses tracking the syllabic rhythm are spatially separable from the MEG responses tracking the sentential and phrasal rhythms.

  14. Hierarchical linear modeling (HLM) of longitudinal brain structural and cognitive changes in alcohol-dependent individuals during sobriety

    DEFF Research Database (Denmark)

    Yeh, P.H.; Gazdzinski, S.; Durazzo, T.C.;

    2007-01-01

    and unique hierarchical linear models allow assessments of the complex relationships among outcome measures of longitudinal data sets. These HLM applications suggest that chronic cigarette smoking modulates the temporal dynamics of brain structural and cognitive changes in alcoholics during prolonged......Background: Hierarchical linear modeling (HLM) can reveal complex relationships between longitudinal outcome measures and their covariates under proper consideration of potentially unequal error variances. We demonstrate the application of FILM to the study of magnetic resonance imaging (MRI...... time points. Using HLM, we modeled volumetric and cognitive outcome measures as a function of cigarette and alcohol use variables. Results: Different hierarchical linear models with unique model structures are presented and discussed. The results show that smaller brain volumes at baseline predict...

  15. Modelling of seismic-electromagnetic Processes in hierarchic Structures, caused by seism-tectonic Activity

    Science.gov (United States)

    Hachay, Olga; Khachay, Andrey

    2013-04-01

    Rock massive can be described by four functions: structure, physical features, content and state. The last feature plays the main role by forecasting the dynamical events which can occur in it. The energy and intensity of the dynamical events depend from the volume of the massive and the space-time changes of the influence on it. The second feature of the state evolution is: the local volume massive does not immediately respond on the changing of the surrounded it stress state. Therefore it stores the response energy and then extracts it through a high energy dynamical effect. It is very significant to define the time of reaction lagging, in spite of the influence on the massive can be assumed as elastic. The unique model which can explain that effect is a model of the massive with a hierarchic structure. We developed a mathematical algorithm using integral and integral-differential equations for 2-D model for two problems in a frequency domain: diffraction a sound wave and linear polarized transverse wave through a arbitrary hierarchy rank inclusion plunged in an N-layered medium. That algorithm differs from the fractal model approach by a freer selecting of heterogeneities position of each rank. And the second the problem is solved in the dynamical approach. The higher the amount of the hierarchic ranks the more is the degree of nonlinearity of the massive response and the longer can be the time of massive reaction lag of the influence. The paper was supported by the grant RFBR 10-05-00013 Key Words: geosynergetics, theory and experimental results.

  16. Bio-inspired hierarchical self-assembly of nanotubes into multi-dimensional and multi-scale structures

    Science.gov (United States)

    Liu, Yong; Gao, Yuan; Lu, Qinghua; Zhou, Yongfeng; Yan, Deyue

    2011-12-01

    As inspired from nature's strategy to prepare collagen, herein we report a hierarchical solution self-assembly method to prepare multi-dimensional and multi-scale supra-structures from the building blocks of pristine titanate nanotubes (TNTs) around 10 nm. With the help of amylose, the nanotubes was continuously self-assembled into helically wrapped TNTs, highly aligned fibres, large bundles, 2D crystal facets and 3D core-shell hybrid crystals. The amyloses work as the glue molecules to drive and direct the hierarchical self-assembly process extending from microscopic to macroscopic scale. The whole self-assembly process as well as the self-assembly structures were carefully characterized by the combination methods of 1H NMR, CD, Hr-SEM, AFM, Hr-TEM, SAED pattern and EDX measurements. A hierarchical self-assembly mechanism was also proposed.As inspired from nature's strategy to prepare collagen, herein we report a hierarchical solution self-assembly method to prepare multi-dimensional and multi-scale supra-structures from the building blocks of pristine titanate nanotubes (TNTs) around 10 nm. With the help of amylose, the nanotubes was continuously self-assembled into helically wrapped TNTs, highly aligned fibres, large bundles, 2D crystal facets and 3D core-shell hybrid crystals. The amyloses work as the glue molecules to drive and direct the hierarchical self-assembly process extending from microscopic to macroscopic scale. The whole self-assembly process as well as the self-assembly structures were carefully characterized by the combination methods of 1H NMR, CD, Hr-SEM, AFM, Hr-TEM, SAED pattern and EDX measurements. A hierarchical self-assembly mechanism was also proposed. Electronic supplementary information (ESI) available: Characterization of the A/TNTs and TNT crystals. See DOI: 10.1039/c1nr11151e

  17. From nano to macro: studying the hierarchical structure of the corneal extracellular matrix.

    Science.gov (United States)

    Quantock, Andrew J; Winkler, Moritz; Parfitt, Geraint J; Young, Robert D; Brown, Donald J; Boote, Craig; Jester, James V

    2015-04-01

    In this review, we discuss current methods for studying ocular extracellular matrix (ECM) assembly from the 'nano' to the 'macro' levels of hierarchical organization. Since collagen is the major structural protein in the eye, providing mechanical strength and controlling ocular shape, the methods presented focus on understanding the molecular assembly of collagen at the nanometre level using X-ray scattering through to the millimetre to centimetre level using non-linear optical (NLO) imaging of second harmonic generated (SHG) signals. Three-dimensional analysis of ECM structure is also discussed, including electron tomography, serial block face scanning electron microscopy (SBF-SEM) and digital image reconstruction. Techniques to detect non-collagenous structural components of the ECM are also presented, and these include immunoelectron microscopy and staining with cationic dyes. Together, these various approaches are providing new insights into the structural blueprint of the ocular ECM, and in particular that of the cornea, which impacts upon our current understanding of the control of corneal shape, pathogenic mechanisms underlying ectatic disorders of the cornea and the potential for corneal tissue engineering. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Hierarchical Network Design

    DEFF Research Database (Denmark)

    Thomadsen, Tommy

    2005-01-01

    Communication networks are immensely important today, since both companies and individuals use numerous services that rely on them. This thesis considers the design of hierarchical (communication) networks. Hierarchical networks consist of layers of networks and are well-suited for coping...... the clusters. The design of hierarchical networks involves clustering of nodes, hub selection, and network design, i.e. selection of links and routing of ows. Hierarchical networks have been in use for decades, but integrated design of these networks has only been considered for very special types of networks....... The thesis investigates models for hierarchical network design and methods used to design such networks. In addition, ring network design is considered, since ring networks commonly appear in the design of hierarchical networks. The thesis introduces hierarchical networks, including a classification scheme...

  19. Femtosecond laser fabrication of highly hydrophobic stainless steel surface with hierarchical structures fabricated by combining ordered microstructures and LIPSS

    Science.gov (United States)

    Martínez-Calderon, M.; Rodríguez, A.; Dias-Ponte, A.; Morant-Miñana, M. C.; Gómez-Aranzadi, M.; Olaizola, S. M.

    2016-06-01

    In this work we have developed hierarchical structures that consist of micro-patterned surfaces covered by nanostructures with a femtosecond laser. The first part of this work is a study to determine the microscale modifications produced on a stainless steel alloy (AISI304) surface at high pulse energy, different velocities, and number of overscans in order to obtain microstructures with a selected depth of around 10 μm and line widths of 20 μm. The second part of the work is focused on finding the optimal irradiation parameters to obtain the nanostructure pattern. Nanostructures have been defined by means of Laser Induced Periodical Surface Structures (LIPSS) around 250 nm high and a period of 580 nm, which constitute the nanostructure pattern. Finally, dual scale gratings of 50 mm2 were fabricated with different geometries and their effect on the measured contact angle. Combining the micro-pattern with the LIPSS nano-pattern, highly hydrophobic surfaces have been developed with measured static contact angles higher than 150° on a stainless steel alloy.

  20. Motion Tree Delineates Hierarchical Structure of Protein Dynamics Observed in Molecular Dynamics Simulation.

    Directory of Open Access Journals (Sweden)

    Kei Moritsugu

    Full Text Available Molecular dynamics (MD simulations of proteins provide important information to understand their functional mechanisms, which are, however, likely to be hidden behind their complicated motions with a wide range of spatial and temporal scales. A straightforward and intuitive analysis of protein dynamics observed in MD simulation trajectories is therefore of growing significance with the large increase in both the simulation time and system size. In this study, we propose a novel description of protein motions based on the hierarchical clustering of fluctuations in the inter-atomic distances calculated from an MD trajectory, which constructs a single tree diagram, named a "Motion Tree", to determine a set of rigid-domain pairs hierarchically along with associated inter-domain fluctuations. The method was first applied to the MD trajectory of substrate-free adenylate kinase to clarify the usefulness of the Motion Tree, which illustrated a clear-cut dynamics picture of the inter-domain motions involving the ATP/AMP lid and the core domain together with the associated amplitudes and correlations. The comparison of two Motion Trees calculated from MD simulations of ligand-free and -bound glutamine binding proteins clarified changes in inherent dynamics upon ligand binding appeared in both large domains and a small loop that stabilized ligand molecule. Another application to a huge protein, a multidrug ATP binding cassette (ABC transporter, captured significant increases of fluctuations upon binding a drug molecule observed in both large scale inter-subunit motions and a motion localized at a transmembrane helix, which may be a trigger to the subsequent structural change from inward-open to outward-open states to transport the drug molecule. These applications demonstrated the capabilities of Motion Trees to provide an at-a-glance view of various sizes of functional motions inherent in the complicated MD trajectory.

  1. Biomolecule-Assisted Hydrothermal Synthesis and Self-Assembly of Bi2Te3 Nanostring-Cluster Hierarchical Structure

    DEFF Research Database (Denmark)

    Mi, Jianli; Lock, Nina; Sun, Ting;

    2010-01-01

    A simple biomolecule-assisted hydrothermal approach has been developed for the fabrication of Bi2Te3 thermoelectric nanomaterials. The product has a nanostring-cluster hierarchical structure which is composed of ordered and aligned platelet-like crystals. The platelets are100 nm in diameter...

  2. Synthesis of a hierarchically structured zeolite-templated carbon starting from fly ash-derived zeolite X

    CSIR Research Space (South Africa)

    Musyoka, Nicholas M

    2014-05-01

    Full Text Available the same morphological features as the parent zeolite and was composed of more than 96% carbon which confirmed that the zeolite template was successfully removed. It is important to emphasize that the hierarchically structured zeolite was produced without...

  3. Self-templated synthesis of TiO2 hierarchical structure photocatalyst with high efficiency and good sedimentation property

    Science.gov (United States)

    Wang, Xiaoning; Sang, Yuanhua; Yu, Xin; Liu, Baishan; Liu, Hong

    2016-10-01

    The balance between highly efficient photocatalysis and a good emulsion/water extraction property is crucial for the practical application of TiO2 photocatalysts. The TiO2 hierarchical structure was synthesized via a hydrothermal treatment of H2Ti3O7 nanobelts with TiF4. The hydrolysis of TiF4 supplies the TiO2 nucleus, and HF, which is derived from the hydrolysis process, acts as a corrosive to etch the H2Ti3O7 nanobelt, resulting in a dynamic dissolution and precipitation process. The etching process resulted in self-generated TiF4 and initiated hydrolysis to generate new TiO2 primary particles. Induced by F etching process, Ti3+ defects were formed in the hierarchical structures, which was beneficial to the photocatalytic property. This hydrolysis-etching-hydrolysis process allows for template dissolution and self-assembly of anatase TiO2 nanobelts to form the TiO2 hierarchical structures. This process balances the nanominiaturization and sedimentation property requirements by the photocatalytic and emulsion/water extraction properties. This simple hydrolysis-etching-hydrolysis process can be applied to the synthesis of many other hierarchical structures.

  4. Synthesis and Visible-Light Photocatalytic Property of Bi2WO6Hierarchical Octahedron-Like Structures

    Directory of Open Access Journals (Sweden)

    Li Yuanyuan

    2008-01-01

    Full Text Available Abstract A novel octahedron-like hierarchical structure of Bi2WO6has been fabricated by a facile hydrothermal method in high quantity. XRD, SEM, TEM, and HRTEM were used to characterize the product. The results indicated that this kind of Bi2WO6crystals had an average size of ~4 μm, constructed by quasi-square single-crystal nanosheets assembled in a special fashion. The formation of octahedron-like hierarchical structure of Bi2WO6depended crucially on the pH value of the precursor suspensions. The photocatalytic activity of the hierarchical Bi2WO6structures toward RhB degradation under visible light was investigated, and it was found to be significantly better than that of the sample fabricated by SSR. The better photocatalytic property should be strongly associated with the high specific surface area and the abundant pore structure of the hierarchical octahedron-like Bi2WO6.

  5. The Impact of Adjacent-Dependencies and Staged-Input on the Learnability of Center-Embedded Hierarchical Structures

    Science.gov (United States)

    Lai, Jun; Poletiek, Fenna H.

    2011-01-01

    A theoretical debate in artificial grammar learning (AGL) regards the learnability of hierarchical structures. Recent studies using an A[superscript n]B[superscript n] grammar draw conflicting conclusions ([Bahlmann and Friederici, 2006] and [De Vries et al., 2008]). We argue that 2 conditions crucially affect learning A[superscript…

  6. Predicting allergic contact dermatitis: a hierarchical structure activity relationship (SAR) approach to chemical classification using topological and quantum chemical descriptors

    Science.gov (United States)

    Basak, Subhash C.; Mills, Denise; Hawkins, Douglas M.

    2008-06-01

    A hierarchical classification study was carried out based on a set of 70 chemicals—35 which produce allergic contact dermatitis (ACD) and 35 which do not. This approach was implemented using a regular ridge regression computer code, followed by conversion of regression output to binary data values. The hierarchical descriptor classes used in the modeling include topostructural (TS), topochemical (TC), and quantum chemical (QC), all of which are based solely on chemical structure. The concordance, sensitivity, and specificity are reported. The model based on the TC descriptors was found to be the best, while the TS model was extremely poor.

  7. Superior supercapacitive performance of hollow activated carbon nanomesh with hierarchical structure derived from poplar catkins

    Science.gov (United States)

    Su, Xiao-Li; Cheng, Ming-Yu; Fu, Lin; Yang, Jing-He; Zheng, Xiu-Cheng; Guan, Xin-Xin

    2017-09-01

    The hollow activated carbon nanomesh (PCACM) with a hierarchical porous structure is derived from biowaste-poplar catkins by in-situ calcination etching with Ni(NO3)2·6H2O and KOH in N2 flow combined with an acid dissolution technique. This procedure not only inherits the natural tube morphology of poplar catkins, but also generates a fascinating nanomesh structure on the walls. PCACM possesses a large specific surface area (SBET = 1893.0 m2 g-1) and high total pore volume (Vp = 1.495 cm3 g-1), and displays an exciting meso-macoporous structure with a concentrated pore size distribution of 4.53 nm. The specific capacitance of PCACM is as high as 314.6 F g-1 at 1.0 A g-1 when used as the electrode materials for supercapacitor. Furthermore, the symmetric supercapacitor of PCACM with 1.0 M Na2SO4 solution as the electrolyte displays a high energy density of 20.86 Wh kg-1 at a power density of 180.13 W kg-1 within a wide voltage rage of 0-1.8 V, which is comparable or even obviously higher than those of other biomass derived carbon reported. It is noteworthy that PCACM also exhibits superior cycling stability and coulombic efficiency. The excellent electrochemical behaviors enable PCACM to be a promising electrode material for supercapacitors.

  8. Detecting a hierarchical genetic population structure via Multi-InDel markers on the X chromosome

    Science.gov (United States)

    Fan, Guang Yao; Ye, Yi; Hou, Yi Ping

    2016-01-01

    Detecting population structure and estimating individual biogeographical ancestry are very important in population genetics studies, biomedical research and forensics. Single-nucleotide polymorphism (SNP) has long been considered to be a primary ancestry-informative marker (AIM), but it is constrained by complex and time-consuming genotyping protocols. Following up on our previous study, we propose that a multi-insertion-deletion polymorphism (Multi-InDel) with multiple haplotypes can be useful in ancestry inference and hierarchical genetic population structures. A validation study for the X chromosome Multi-InDel marker (X-Multi-InDel) as a novel AIM was conducted. Genetic polymorphisms and genetic distances among three Chinese populations and 14 worldwide populations obtained from the 1000 Genomes database were analyzed. A Bayesian clustering method (STRUCTURE) was used to discern the continental origins of Europe, East Asia, and Africa. A minimal panel of ten X-Multi-InDels was verified to be sufficient to distinguish human ancestries from three major continental regions with nearly the same efficiency of the earlier panel with 21 insertion-deletion AIMs. Along with the development of more X-Multi-InDels, an approach using this novel marker has the potential for broad applicability as a cost-effective tool toward more accurate determinations of individual biogeographical ancestry and population stratification. PMID:27535707

  9. Zipf's Law, Hierarchical Structure, and Cards-Shuffling Model for Urban Development

    Directory of Open Access Journals (Sweden)

    Yanguang Chen

    2012-01-01

    Full Text Available Hierarchy of cities reflects the ubiquitous structure frequently observed in the natural world and social institutions. Where there is a hierarchy with cascade structure, there is a Zipf's rank-size distribution, and vice versa. However, we have no theory to explain the spatial dynamics associated with Zipf's law of cities. In this paper, a new angle of view is proposed to find the simple rules dominating complex systems and regular patterns behind random distribution of cities. The hierarchical structure can be described with a set of exponential functions that are identical in form to Horton-Strahler's laws on rivers and Gutenberg-Richter's laws on earthquake energy. From the exponential models, we can derive four power laws including Zipf's law indicative of fractals and scaling symmetry. A card-shuffling model is built to interpret the relation between Zipf's law and hierarchy of cities. This model can be expanded to illuminate the general empirical power-law distributions across the individual physical and social sciences, which are hard to be comprehended within the specific scientific domains. This research is useful for us to understand how complex systems such as networks of cities are self-organized.

  10. Zipf's law, Hierarchical Structure, and Shuffling-Cards Model for Urban Development

    CERN Document Server

    Chen, Yanguang

    2011-01-01

    A new angle of view is proposed to find the simple rules dominating complex systems and regular patterns behind random phenomena such as cities. Hierarchy of cities reflects the ubiquitous structure frequently observed in the natural world and social institutions. Where there is a hierarchy with cascade structure, there is a rank-size distribution following Zipf's law, and vice versa. The hierarchical structure can be described with a set of exponential functions that are identical in form to Horton-Strahler's laws on rivers and Gutenberg-Richter's laws on earthquake energy. From the exponential models, we can derive four power laws such as Zipf's law indicative of fractals and scaling symmetry. Research on the hierarchy is revealing for us to understand how complex systems are self-organized. A card-shuffling model is built to interpret the relation between Zipf's law and hierarchy of cities. This model can be expanded to explain the general empirical power-law distributions across the individual physical an...

  11. On the internal consistency of the term structure of forecasts of housing starts

    DEFF Research Database (Denmark)

    Pierdzioch, C.; Rulke, J. C.; Stadtmann, G.

    2013-01-01

    We use the term structure of forecasts of housing starts to test for rationality of forecasts. Our test is based on the idea that short-term and long-term forecasts should be internally consistent. We test the internal consistency of forecasts using data for Australia, Canada, Japan and the Unite...... States. Using a simple model of forecast formation, we find that forecasts are not internally consistent, leading to a rejection of forecast rationality....

  12. Hierarchical progressive surveys. Multi-resolution HEALPix data structures for astronomical images, catalogues, and 3-dimensional data cubes

    CERN Document Server

    Fernique, P; Boch, T; Oberto, A; Pineau, F-X; Durand, D; Bot, C; Cambresy, L; Derriere, S; Genova, F; Bonnarel, F

    2015-01-01

    Scientific exploitation of the ever increasing volumes of astronomical data requires efficient and practical methods for data access, visualisation, and analysis. Hierarchical sky tessellation techniques enable a multi-resolution approach to organising data on angular scales from the full sky down to the individual image pixels. Aims. We aim to show that the Hierarchical progressive survey (HiPS) scheme for describing astronomical images, source catalogues, and three-dimensional data cubes is a practical solution to managing large volumes of heterogeneous data and that it enables a new level of scientific interoperability across large collections of data of these different data types. Methods. HiPS uses the HEALPix tessellation of the sphere to define a hierarchical tile and pixel structure to describe and organise astronomical data. HiPS is designed to conserve the scientific properties of the data alongside both visualisation considerations and emphasis on the ease of implementation. We describe the develop...

  13. Hierarchical mixture of experts and diagnostic modeling approach to reduce hydrologic model structural uncertainty: STRUCTURAL UNCERTAINTY DIAGNOSTICS

    Energy Technology Data Exchange (ETDEWEB)

    Moges, Edom [Civil and Environmental Engineering Department, Washington State University, Richland Washington USA; Demissie, Yonas [Civil and Environmental Engineering Department, Washington State University, Richland Washington USA; Li, Hong-Yi [Hydrology Group, Pacific Northwest National Laboratory, Richland Washington USA

    2016-04-01

    In most water resources applications, a single model structure might be inadequate to capture the dynamic multi-scale interactions among different hydrological processes. Calibrating single models for dynamic catchments, where multiple dominant processes exist, can result in displacement of errors from structure to parameters, which in turn leads to over-correction and biased predictions. An alternative to a single model structure is to develop local expert structures that are effective in representing the dominant components of the hydrologic process and adaptively integrate them based on an indicator variable. In this study, the Hierarchical Mixture of Experts (HME) framework is applied to integrate expert model structures representing the different components of the hydrologic process. Various signature diagnostic analyses are used to assess the presence of multiple dominant processes and the adequacy of a single model, as well as to identify the structures of the expert models. The approaches are applied for two distinct catchments, the Guadalupe River (Texas) and the French Broad River (North Carolina) from the Model Parameter Estimation Experiment (MOPEX), using different structures of the HBV model. The results show that the HME approach has a better performance over the single model for the Guadalupe catchment, where multiple dominant processes are witnessed through diagnostic measures. Whereas, the diagnostics and aggregated performance measures prove that French Broad has a homogeneous catchment response, making the single model adequate to capture the response.

  14. Hierarchical QSAR technology based on the Simplex representation of molecular structure.

    Science.gov (United States)

    Kuz'min, V E; Artemenko, A G; Muratov, E N

    2008-01-01

    This article is about the hierarchical quantitative structure-activity relationship technology (HiT QSAR) based on the Simplex representation of molecular structure (SiRMS) and its application for different QSAR/QSP(property)R tasks. The essence of this technology is a sequential solution (with the use of the information obtained on the previous steps) to the QSAR problem by the series of enhanced models of molecular structure description [from one dimensional (1D) to four dimensional (4D)]. It is a system of permanently improved solutions. In the SiRMS approach, every molecule is represented as a system of different simplexes (tetratomic fragments with fixed composition, structure, chirality and symmetry). The level of simplex descriptors detailing increases consecutively from the 1D to 4D representation of the molecular structure. The advantages of the approach reported here are the absence of "molecular alignment" problems, consideration of different physical-chemical properties of atoms (e.g. charge, lipophilicity, etc.), the high adequacy and good interpretability of obtained models and clear ways for molecular design. The efficiency of the HiT QSAR approach is demonstrated by comparing it with the most popular modern QSAR approaches on two representative examination sets. The examples of successful application of the HiT QSAR for various QSAR/QSPR investigations on the different levels (1D-4D) of the molecular structure description are also highlighted. The reliability of developed QSAR models as predictive virtual screening tools and their ability to serve as the base of directed drug design was validated by subsequent synthetic and biological experiments, among others. The HiT QSAR is realized as a complex of computer programs known as HIT QSAR: software that also includes a powerful statistical block and a number of useful utilities.

  15. Preparation and performance of tubular nanoflaky (Ni, Co, Mn) oxides with hierarchical mesoporous structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao; Fu, Yanqing; Wang, Xianyou, E-mail: wxianyou@yahoo.com; Gao, Jiao; Zhang, Youwei; Zhao, Qinglan

    2015-08-05

    Highlights: • The nickel cobalt manganese oxide with nanosheet-like nanotube structure is firstly reported. • The novel composite possess high specific surface area of 134.1 m{sup 2} g{sup −1}. • The novel composite deliver superior electrochemical behaviors. - Abstract: The nickel cobalt manganese oxide (NCMO/CNT) with hierarchical tubular nanoflaky structure is intentionally designed and synthesized via a facile method by using carbon nanotube (CNT) as a backbone template, then the nickel cobalt manganese oxide with nanosheet-like nanotube structure (NCMONST) is synthesized after removed successfully the CNT templates. The morphology, structure and physicochemical properties of the NCMONST samples are characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and nitrogen adsorption–desorption isotherms. The results reveal that the NCMO shell with a thickness of 0.2 μm grows uniformly on the surface of the CNT with a diameter of 0.1 μm. After calcined NCMO/CNT in air, the mesoporous NCMONST is successfully obtained. The as-prepared NCMONST maintains the tubular and sheets-like structure of NCMO/CNT, and possesses a high specific surface area of 134.1 m{sup 2} g{sup −1}, large pore volume of 0.609 cm{sup 3} g{sup −1} and broad pore-size distribution. The electrochemical results show that the NCMONST exhibits a high specific capacitance of 680 F g{sup −1} at 1 A g{sup −1}, excellent rate capability of 38% at 20 A g{sup −1} and good capacity retention of 88% after 1000 cycles. Therefore, the transition metal oxide with porous structure is a promising electrode candidate for the application of supercapacitors.

  16. Hierarchical QSAR technology based on the Simplex representation of molecular structure

    Science.gov (United States)

    Kuz'min, V. E.; Artemenko, A. G.; Muratov, E. N.

    2008-06-01

    This article is about the hierarchical quantitative structure-activity relationship technology (HiT QSAR) based on the Simplex representation of molecular structure (SiRMS) and its application for different QSAR/QSP(property)R tasks. The essence of this technology is a sequential solution (with the use of the information obtained on the previous steps) to the QSAR problem by the series of enhanced models of molecular structure description [from one dimensional (1D) to four dimensional (4D)]. It is a system of permanently improved solutions. In the SiRMS approach, every molecule is represented as a system of different simplexes (tetratomic fragments with fixed composition, structure, chirality and symmetry). The level of simplex descriptors detailing increases consecutively from the 1D to 4D representation of the molecular structure. The advantages of the approach reported here are the absence of "molecular alignment" problems, consideration of different physical-chemical properties of atoms (e.g. charge, lipophilicity, etc.), the high adequacy and good interpretability of obtained models and clear ways for molecular design. The efficiency of the HiT QSAR approach is demonstrated by comparing it with the most popular modern QSAR approaches on two representative examination sets. The examples of successful application of the HiT QSAR for various QSAR/QSPR investigations on the different levels (1D-4D) of the molecular structure description are also highlighted. The reliability of developed QSAR models as predictive virtual screening tools and their ability to serve as the base of directed drug design was validated by subsequent synthetic and biological experiments, among others. The HiT QSAR is realized as a complex of computer programs known as HiT QSAR software that also includes a powerful statistical block and a number of useful utilities.

  17. Hierarchical alteration of brain structural and functional networks in female migraine sufferers.

    Directory of Open Access Journals (Sweden)

    Jixin Liu

    Full Text Available BACKGROUND: Little is known about the changes of brain structural and functional connectivity networks underlying the pathophysiology in migraine. We aimed to investigate how the cortical network reorganization is altered by frequent cortical overstimulation associated with migraine. METHODOLOGY/PRINCIPAL FINDINGS: Gray matter volumes and resting-state functional magnetic resonance imaging signal correlations were employed to construct structural and functional networks between brain regions in 43 female patients with migraine (PM and 43 gender-matched healthy controls (HC by using graph theory-based approaches. Compared with the HC group, the patients showed abnormal global topology in both structural and functional networks, characterized by higher mean clustering coefficients without significant change in the shortest absolute path length, which indicated that the PM lost optimal topological organization in their cortical networks. Brain hubs related to pain-processing revealed abnormal nodal centrality in both structural and functional networks, including the precentral gyrus, orbital part of the inferior frontal gyrus, parahippocampal gyrus, anterior cingulate gyrus, thalamus, temporal pole of the middle temporal gyrus and the inferior parietal gyrus. Negative correlations were found between migraine duration and regions with abnormal centrality. Furthermore, the dysfunctional connections in patients' cortical networks formed into a connected component and three dysregulated modules were identified involving pain-related information processing and motion-processing visual networks. CONCLUSIONS: Our results may reflect brain alteration dynamics resulting from migraine and suggest that long-term and high-frequency headache attacks may cause both structural and functional connectivity network reorganization. The disrupted information exchange between brain areas in migraine may be reshaped into a hierarchical modular structure progressively.

  18. Consistency of Semantic Meaning with Structure andFunction in English Writing

    Institute of Scientific and Technical Information of China (English)

    马文静; 张丽婧

    2015-01-01

    Writing is one of the skills most difficult to train and develop.Although writing can be circumvented in many cases bysome people, modern civilization is imposing increasing demands on our ability to write, and write well. In English writing,consistency of semantic meaning with structure and function in English writing is a very important part to evaluate the quality ofwriting.In student's English academic writing, there are different writing types. The consistency of semanticmeaning with structureand function in different academic writings is various. In this thesis, the consistency of the semantic meaning with structure andfunction in the essay and academic and report writing is analyzed.

  19. Durable polyorganosiloxane superhydrophobic films with a hierarchical structure by sol-gel and heat treatment method

    Science.gov (United States)

    Jiang, Zhenlin; Fang, Shuying; Wang, Chaosheng; Wang, Huaping; Ji, Chengchang

    2016-12-01

    For a surface to be superhydrophobic a combination of surface roughness and low surface energy is required. In this study, polyorganosiloxane superhydrophobic surfaces were fabricated using a sol-gel and heat treatment process followed by coating with a nanosilica (SiO2) sol and organosiloxane 1, 1, 1, 3, 5, 5, 5-heptamethyl-3-[2-(trimethoxysilyl)ethyl]-trisiloxane (β-HPEOs). The nano-structure was superimposed using self-assembled, surface-modified silica nanoparticles, forming two-dimensional hierarchical structures. The water contact angle (WCA) of polyorganosiloxane superhydrophobic surface was 143.7 ± 0.6°, which was further increased to 156.7 ± 1.1° with water angle hysteresis of 2.5 ± 0.6° by superimposing nanoparticles using a heat treatment process. An analytical characterization of the surface revealed that the nano-silica and polyorganosiloxane formed a micro/nano structure on the films and the wetting behaviour of the films changed from hydrophilic to superhydrophobic. The WCA of these films were 143.7 ± 0.6° and at heat treatment temperatures of less than 400 °C, the WCA increased from 144.5 ± 0.7° to 156.7 ± 1.1°. The prepared superhydrophobic films were stable even after heat treatment at 430 °C for 30 min and their superhydrophobicity was durable for more than 120 days. The effects of heat treatment process on the surface chemistry structure, wettability and morphology of the polyorganosiloxane superhydrophobic films were investigated in detail. The results indicated that the stability of the chemical structure was required to yield a thermally-stable superhydrophobic surface.

  20. Hierarchical fiber-optic delamination detection system for carbon fiber reinforced plastic structures

    Science.gov (United States)

    Minakuchi, Shu; Banshoya, Hidehiko; Shingo, Ii; Takeda, Nobuo

    2012-10-01

    This study develops a delamination detection system by extending our previous approach for monitoring surface cracks in a large-scale composite structure. In the new system, numerous thin glass capillaries are embedded into a composite structure, and internal pressure in the built-in capillary sensors, based on comparative vacuum monitoring (CVM), is maintained as a vacuum. When delamination is induced, the capillary sensors located within the delaminated area are breached, and atmospheric air flows into the capillaries. The consequent pressure change within the capillaries is then converted into axial strain in a surface-mounted optical fiber through a transducing mechanism, which is connected to the capillaries. By monitoring the strain distribution along the optical fiber, it is possible to identify a transducing mechanism in which the pressure change occurred and thus to specify the location of the delamination. This study begins by establishing a novel sensor embedding/extracting method. The airflow characteristic in the capillary sensors is then comprehensively evaluated, determining the basic performance of the new system. The proposed detection technique is validated by taking a step-by-step approach, and finally the hierarchical fiber-optic delamination detection system is demonstrated. A further advance to be combined with a self-healing concept is also discussed.

  1. Insights into the hierarchical structure and digestion rate of alkali-modulated starches with different amylose contents.

    Science.gov (United States)

    Qiao, Dongling; Yu, Long; Liu, Hongsheng; Zou, Wei; Xie, Fengwei; Simon, George; Petinakis, Eustathios; Shen, Zhiqi; Chen, Ling

    2016-06-25

    Combined analytical techniques were used to explore the effects of alkali treatment on the multi-scale structure and digestion behavior of starches with different amylose/amylopectin ratios. Alkali treatment disrupted the amorphous matrix, and partial lamellae and crystallites, which weakened starch molecular packing and eventually enhanced the susceptibility of starch to alkali. Stronger alkali treatment (0.5% w/w) made this effect more prominent and even transformed the dual-phase digestion of starch into a triple-phase pattern. Compared with high-amylose starch, regular maize starch, which possesses some unique structure characteristics typically as pores and crystallite weak points, showed evident changes of hierarchical structure and in digestion rate. Thus, alkali treatment has been demonstrated as a simple method to modulate starch hierarchical structure and thus to realize the rational development of starch-based food products with desired digestibility.

  2. Hierarchical organization of the coordinative structure of the skill of clay kneading.

    Science.gov (United States)

    Yamamoto, Tomoyuki; Fujinami, Tsutomu

    2008-10-01

    An experiment was conducted to study the skill of clay kneading in pottery. This task usually requires a few years to master and is therefore well suited to study the long-term development of a complex motor skill. Participants' kneading movements were measured in 3D using a motion capture device and phase relations among coordinates and joint angles were analyzed in terms of the mutual phase relative to a reference point using the Hilbert transform. While a certain degree of periodicity was observed in all 10 participants, the behavior of the experts was characterized by a significant delay for the right elbow (i.e., the pushing arm) and the fore-aft position of the upper torso and only brief delays for the other parts, which all tended to synchronize with the reference. These findings are consistent with our notion of "differentiation within coordination", according to which skill learning proceeds in a hierarchical manner in that coordination among limb movements is established first, followed by modulations of specific limb movements within the established coordination. Although this feature of expert behavior was also apparent in our previous studies of clay kneading and samba shaking and dancing, the numbers of participants in those studies were not sufficient to draw firm conclusions. Since the present study involved more participants and a superior method of analysis, the present evidence for the principle of differentiation within coordination is more conclusive.

  3. A top-down approach for fabricating free-standing bio-carbon supercapacitor electrodes with a hierarchical structure

    OpenAIRE

    Yingzhi Li; Qinghua Zhang; Junxian Zhang; Lei Jin; Xin Zhao; Ting Xu

    2015-01-01

    Biomass has delicate hierarchical structures, which inspired us to develop a cost-effective route to prepare electrode materials with rational nanostructures for use in high-performance storage devices. Here, we demonstrate a novel top-down approach for fabricating bio-carbon materials with stable structures and excellent diffusion pathways; this approach is based on carbonization with controlled chemical activation. The developed free-standing bio-carbon electrode exhibits a high specific ca...

  4. Solvent-mediated gel formation, hierarchical structures, and rheological properties of organogels.

    Science.gov (United States)

    Su, Ming-Ming; Yang, Hai-Kuan; Ren, Li-Jun; Zheng, Ping; Wang, Wei

    2015-01-28

    We report the formation of solvent-mediated gels as well as their hierarchical structures and rheological properties. The gelator used is a hybrid with a molecular structure of cholesterol-polyoxometalate-cholesterol, in which the cholesterol dissolves well in toluene and N,N-dimethylformamide (DMF), whereas the polyoxometalate cluster dissolves only in DMF. These solubility differences enable the gelator to form thermally reversible supramolecular organogels by mixing solvents of toluene and DMF when the volume fraction, ftol, of toluene is larger than 85.7 v/v%. We found a V-shaped correlation between the gelation times, tgel and ftol: tgel decreases from 1300 min to 2 min when ftol increases from 85.7 v/v% to 90.0 v/v%. It then increases from 2 min to 5800 min when ftol further increases from 90.0 v/v% to 100.0 v/v%. We observed ribbon-like self-assembled structures in the gels as well as a structural evolution from rigid and straight ribbons to twistable ones from ftol=85.7 v/v% to ftol=100.0 v/v%. These ribbons constitute two three-dimensional (3D) gel networks: one is constructed via physical connection of the rigid and straight ribbon, and the other is built up from ribbons splitting and intertwining. The latter has a better 3D gel network that offers improved rheological properties. Fundamentally, this solvent-mediated approach regulates the balance between solubility and insolubility of this gelator in the mixing solvents. It also provides a new method for the preparation of organogels.

  5. The neural processing of hierarchical structure in music and speech at different timescales

    Directory of Open Access Journals (Sweden)

    Morwaread Mary Farbood

    2015-05-01

    Full Text Available Music, like speech, is a complex auditory signal that contains structures at multiple timescales, and as such a potentially powerful entry point into the question of how the brain integrates complex streams of information. Using an experimental design modeled after previous studies that used scrambled versions of a spoken story (Lerner, Honey, Silbert, & Hasson, 2011 and a silent movie (Hasson, Yang, Vallines, Heeger, & Rubin, 2008, we investigate whether listeners perceive hierarchical structure in music beyond short (~6 sec time windows and whether there is cortical overlap between music and language processing at multiple timescales. Experienced pianists were presented with an extended musical excerpt scrambled at multiple timescales––by measure, phrase, and section––while measuring brain activity with functional magnetic resonance imaging (fMRI. The reliability of evoked activity, as quantified by inter-subject correlation of the fMRI responses was measured. We found that response reliability depended systematically on musical structural coherence, revealing a topographically organized hierarchy of processing timescales. Early auditory areas (at the bottom of the hierarchy responded reliably in all conditions. For brain areas at the top of the hierarchy, the original (unscrambled excerpt evoked more reliable responses than any of the scrambled excerpts, indicating that these brain areas process long-timescale musical structures, on the order of minutes. The topography of processing timescales was analogous with that reported previously for speech, but the timescale gradients for music and speech overlapped with one another only partially, suggesting that temporally analogous structures––words/measures, sentences/musical phrases, paragraph/sections––are processed separately.

  6. The neural processing of hierarchical structure in music and speech at different timescales

    Science.gov (United States)

    Farbood, Morwaread M.; Heeger, David J.; Marcus, Gary; Hasson, Uri; Lerner, Yulia

    2015-01-01

    Music, like speech, is a complex auditory signal that contains structures at multiple timescales, and as such is a potentially powerful entry point into the question of how the brain integrates complex streams of information. Using an experimental design modeled after previous studies that used scrambled versions of a spoken story (Lerner et al., 2011) and a silent movie (Hasson et al., 2008), we investigate whether listeners perceive hierarchical structure in music beyond short (~6 s) time windows and whether there is cortical overlap between music and language processing at multiple timescales. Experienced pianists were presented with an extended musical excerpt scrambled at multiple timescales—by measure, phrase, and section—while measuring brain activity with functional magnetic resonance imaging (fMRI). The reliability of evoked activity, as quantified by inter-subject correlation of the fMRI responses, was measured. We found that response reliability depended systematically on musical structure coherence, revealing a topographically organized hierarchy of processing timescales. Early auditory areas (at the bottom of the hierarchy) responded reliably in all conditions. For brain areas at the top of the hierarchy, the original (unscrambled) excerpt evoked more reliable responses than any of the scrambled excerpts, indicating that these brain areas process long-timescale musical structures, on the order of minutes. The topography of processing timescales was analogous with that reported previously for speech, but the timescale gradients for music and speech overlapped with one another only partially, suggesting that temporally analogous structures—words/measures, sentences/musical phrases, paragraph/sections—are processed separately. PMID:26029037

  7. Reflection of hierarchical medium structures of different scales in the space time data of wave fields distribution.

    Science.gov (United States)

    Hachay, Olga; Khachay, Andrey

    2015-04-01

    The last decades are characterized by active development of Earth's sciences. The modern research methods and technologies give the opportunity to obtain new data about the Earth's structure and processes, which occur in its interior. The conception development about the nonlinear geodynamics practically coincides with research of nonlinear processes in different parts of physics. In geology soliton and auto wave conceptions are developed, principles of synergetic and self organization become be used, in geodynamics the macro quantum behavior of large mass matter, which are in critical state, in geophysics the auto wave nature of geophysical fields is researched in a frame of a new structural model with hierarchical inclusions. It is very significant to define the time of reaction lagging, in spite of the influence on the massif can be assumed as elastic. The unique model which can explain that effect is a model of the massif with a hierarchic structure. We developed a mathematical algorithm using integral and integral-differential equations for 2-D model for two problems in a frequency domain: diffraction a sound wave and linear polarized transverse wave through a arbitrary hierarchy rank inclusion plunged in an N-layered medium. That algorithm differs from the fractal model approach by a freer selecting of heterogeneities position of each rank. And the second, the problem is solved in the dynamical approach. The higher the amount of the hierarchic ranks the more is the degree of nonlinearity of the massive response and the longer can be the time of massive reaction lag of the influence. For research of hierarchic medium we had developed an iterative algorithm for electromagnetic and seismic fields in the problem setting similar to analyze higher for layered-block models with homogeneous inclusions. We had developed an iterative algorithm of inverse problem solution for the same models, using the approach of three stage interpretation. For that we had developed a

  8. AFM study of excimer laser patterning of block-copolymer: Creation of ordered hierarchical, hybrid, or recessed structures

    Science.gov (United States)

    Švanda, Jan; Siegel, Jakub; Švorčík, Vaclav; Lyutakov, Oleksiy

    2016-05-01

    We report fabrication of the varied range of hierarchical structures by combining bottom-up self-assembly of block copolymer poly(styrene-block-vinylpyridine) (PS-b-P4VP) with top-down excimer laser patterning method. Different procedures were tested, where laser treatment was applied before phase separation and after phase separation or phase separation and surface reconstruction. Laser treatment was performed using either polarized laser light with the aim to create periodical pattern on polymer surface or non-polarized light for preferential removing of polystyrene (PS) part from PS-b-P4VP. Additionally, dye was introduced into one part of block copolymer (P4VP) with the aim to modify its response to laser light. Resulting structures were analyzed by XPS, UV-vis and AFM techniques. Application of polarized laser light leads to creation of structures with hierarchical, recessed or hybrid geometries. Non-polarized laser beam allows pronouncing the block copolymer phase separated structure. Tuning the order of steps or individual step conditions enables the efficient reorientation of block-copolymer domain at large scale, fabrication of hierarchical, hybrid or recessed structures. The obtained structures can find potential applications in nanotechnology, photonics, plasmonics, information storage, optical devices, sensors and smart surfaces.

  9. Characterization of the effects of x-ray irradiation on the hierarchical structure and mechanical properties of human cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Holly; Zimmermann, Elizabeth; Schaible, Eric; Tang, Simon; Alliston, Tamara; Ritchie, Robert

    2011-08-19

    Bone comprises a complex structure of primarily collagen, hydroxyapatite and water, where each hierarchical structural level contributes to its strength, ductility and toughness. These properties, however, are degraded by irradiation, arising from medical therapy or bone-allograft sterilization. We provide here a mechanistic framework for how irradiation affects the nature and properties of human cortical bone over a range of characteristic (nano to macro) length-scales, following x-­ray exposures up to 630 kGy. Macroscopically, bone strength, ductility and fracture resistance are seen to be progressively degraded with increasing irradiation levels. At the micron-­scale, fracture properties, evaluated using in-situ scanning electron microscopy and synchrotron x-ray computed micro-tomography, provide mechanistic information on how cracks interact with the bone-matrix structure. At sub-micron scales, strength properties are evaluated with in-situ tensile tests in the synchrotron using small-/wide-angle x-ray scattering/diffraction, where strains are simultaneously measured in the macroscopic tissue, collagen fibrils and mineral. Compared to healthy bone, results show that the fibrillar strain is decreased by ~40% following 70 kGy exposures, consistent with significant stiffening and degradation of the collagen. We attribute the irradiation-­induced deterioration in mechanical properties to mechanisms at multiple length-scales, including changes in crack paths at micron-­scales, loss of plasticity from suppressed fibrillar sliding at sub-­micron scales, and the loss and damage of collagen at the nano-­scales, the latter being assessed using Raman and Fourier-Transform-Infrared spectroscopy and a fluorometric assay.

  10. Hierarchical structure of mitochondrial DNA gene flow among humpback whales Megaptera novaeangliae, world-wide.

    Science.gov (United States)

    Baker, C S; Slade, R W; Bannister, J L; Abernethy, R B; Weinrich, M T; Lien, J; Urban, J; Corkeron, P; Calmabokidis, J; Vasquez, O

    1994-08-01

    The genetic structure of humpback whale populations and subpopulation divisions is described by restriction fragment length analysis of the mitochondrial (mt) DNA from samples of 230 whales collected by biopsy darting in 11 seasonal habitats representing six subpopulations, or 'stocks', world-wide. The hierarchical structure of mtDNA haplotype diversity among population subdivisions is described using the analysis of molecular variance (AMOVA) procedure, the analysis of gene identity, and the genealogical relationship of haplotypes as constructed by parsimony analysis and distance clustering. These analyses revealed: (i) significant partitioning of world-wide genetic variation among oceanic populations, among subpopulations or 'stocks' within oceanic populations and among seasonal habitats within stocks; (ii) fixed categorical segregation of haplotypes on the south-eastern Alaska and central California feeding grounds of the North Pacific; (iii) support for the division of the North Pacific population into a central stock which feeds in Alaska and winters in Hawaii, and an eastern or 'American' stock which feeds along the coast of California and winters near Mexico; (iv) evidence of genetic heterogeneity within the Gulf of Maine feeding grounds and among the sampled feeding and breeding grounds of the western North Atlantic; and (v) support for the historical division between the Group IV (Western Australia) and Group V (eastern Australia, New Zealand and Tonga) stocks in the Southern Oceans. Overall, our results demonstrate a striking degree of genetic structure both within and between oceanic populations of humpback whales, despite the nearly unlimited migratory potential of this species. We suggest that the humpback whale is a suitable demographic and genetic model for the management of less tractable species of baleen whales and for the general study of gene flow among long-lived, mobile vertebrates in the marine ecosystem.

  11. Fabrication and in vitro characterization of magnetic hydroxycarbonate apatite coatings with hierarchically porous structures.

    Science.gov (United States)

    Guo, Yaping; Zhou, Yu; Jia, Dechang; Meng, Qingchang

    2008-07-01

    Hydroxycarbonate apatite/Fe(3)O(4) composite coatings (MHACs) with hierarchically porous structures were fabricated by electrophoretic deposition of CaCO(3)/Fe(3)O(4) particles on Ti6Al4V substrates followed by treatment with phosphate buffer solution (PBS) at 37 degrees C. The effects of Fe(3)O(4) on the conversion rate of calcium carbonate to hydroxycarbonate apatite and the porous structures and in vitro bioactivity of MHACs were investigated. After soaking CaCO(3)/Fe(3)O(4) coatings in PBS, hydroxycarbonate apatite nucleates heterogeneously on the surfaces of CaCO(3)/Fe(3)O(4) particles and forms a plate-like structure. Fe(3)O(4) increases the velocity of nucleus formation of hydroxycarbonate apatite. After soaking for 1day, the percentage of unreacted calcium carbonate for MHACs is approximately 9.1%, lower than the approximately 41.0% for hydroxycarbonate apatite coatings (HCACs). As the CaCO(3)/Fe(3)O(4) coatings are converted to MHACs, macropores with a pore size of approximately 4mum on the coatings and mesopores with a pore size of approximately 3.9nm within the hydroxycarbonate apatite plates are formed. The mesopores remain in the MHACs after treatment with PBS for 9 days, while they disappear in the HCACs. Simulated body fluid immersion tests reveal that Fe(3)O(4) improves the in vitro bioactivity of biocoatings. The amount of bone-like apatite precipitated on the surfaces of MHACs is greater than that on the surfaces of HCACs.

  12. Challenges in engineering osteochondral tissue grafts with hierarchical structures Ivana Gadjanski, Gordana Vunjak Novakovic

    Science.gov (United States)

    Gadjanski, Ivana; Vunjak-Novakovic, Gordana

    2015-01-01

    Introduction A major hurdle in treating osteochondral (OC) defects are the different healing abilities of two types of tissues involved - articular cartilage and subchondral bone. Biomimetic approaches to OC-construct-engineering, based on recapitulation of biological principles of tissue development and regeneration, have potential for providing new treatments and advancing fundamental studies of OC tissue repair. Areas covered This review on state of the art in hierarchical OC tissue graft engineering is focused on tissue engineering approaches designed to recapitulate the native milieu of cartilage and bone development. These biomimetic systems are discussed with relevance to bioreactor cultivation of clinically sized, anatomically shaped human cartilage/bone constructs with physiologic stratification and mechanical properties. The utility of engineered OC tissue constructs is evaluated for their use as grafts in regenerative medicine, and as high-fidelity models in biological research. Expert opinion A major challenge in engineering OC tissues is to generate a functionally integrated stratified cartilage-bone structure starting from one single population of mesenchymal cells, while incorporating perfusable vasculature into the bone, and in bone-cartilage interface. To this end, new generations of advanced scaffolds and bioreactors, implementation of mechanical loading regimens, and harnessing of inflammatory responses of the host will likely drive the further progress. PMID:26195329

  13. SO2 Emissions in China – Their Network and Hierarchical Structures

    Science.gov (United States)

    Yan, Shaomin; Wu, Guang

    2017-01-01

    SO2 emissions lead to various harmful effects on environment and human health. The SO2 emission in China has significant contribution to the global SO2 emission, so it is necessary to employ various methods to study SO2 emissions in China with great details in order to lay the foundation for policymaking to improve environmental conditions in China. Network analysis is used to analyze the SO2 emissions from power generation, industrial, residential and transportation sectors in China for 2008 and 2010, which are recently available from 1744 ground surface monitoring stations. The results show that the SO2 emissions from power generation sector were highly individualized as small-sized clusters, the SO2 emissions from industrial sector underwent an integration process with a large cluster contained 1674 places covering all industrial areas in China, the SO2 emissions from residential sector was not impacted by time, and the SO2 emissions from transportation sector underwent significant integration. Hierarchical structure is obtained by further combining SO2 emissions from all four sectors and is potentially useful to find out similar patterns of SO2 emissions, which can provide information on understanding the mechanisms of SO2 pollution and on designing different environmental measure to combat SO2 emissions. PMID:28387301

  14. The Magellanic Satellites Survey: Searching for Hierarchical Structure Formation within the Local Group

    Science.gov (United States)

    Bechtol, Keith; Magellanic Satellites Survey (MagLiteS)

    2017-01-01

    A generic prediction of galaxy formation in the standard cosmological model with cold dark matter is the hierarchical assembly of structure on mass scales ranging from ultra-faint galaxies to galaxy clusters. In the Local Group, dozens of galaxies have been found orbiting the Milky Way and Andromeda. The question of whether the largest Milky Way satellites, the Large and Small Magellanic Clouds, brought in their own entourage of satellites has been a long standing puzzle, and has garnered renewed interest following the recent discovery of more than a dozen ultra-faint galaxy candidates in the southern hemisphere. The on-going Magellanic Satellites Survey (MagLiteS) aims to complete an annulus of contiguous deep optical imaging with Blanco/DECam around the periphery of the Magellanic Clouds, enabling a systematic search for ultra-faint galaxies and other low-surface-brightness stellar substructures associated with the Magellanic system. I will report on the progress of MagLiteS and discuss science highlights from the first observing season, including a new ultra-faint galaxy candidate located ~11 kpc from the Large Magellanic Cloud.

  15. Hierarchical structure and dynamics of an ionic liquid 1-octyl-3-methylimidazolium chloride.

    Science.gov (United States)

    Yamamuro, Osamu; Yamada, Takeshi; Kofu, Maiko; Nakakoshi, Masamichi; Nagao, Michihiro

    2011-08-07

    We have performed the heat capacity, neutron diffraction, and neutron quasielastic scattering measurements of an ionic liquid 1-octyl-3-methylimidazolium chloride (C8mimCl). The heat capacity data revealed that C8mimCl exhibits a glass transition with a large heat capacity jump at T(g) = 214 K, which is lower than T(g) of C4mimCl with a shorter alkyl-chain. In the neutron diffraction measurement for a deuterated analogue, d-C8mimCl, the peaks associated with the inter-domain, inter-ionic, and inter-alkyl-chain correlations appeared at (3, 11, and 14) nm(-1), respectively. The temperature dependence of these peaks indicates that the packing of the alkyl-chains becomes more compact and the domains become more vivid and larger as decreasing temperature. The quasielastic neutron scattering measurements using neutron spin echo and time-of-flight type instruments demonstrated that C8mimCl has faster relaxations probably owing to the alkyl-group and a slower relaxation owing to the ions. The latter relaxation, which is related to the glass transition, is of non-exponential as in the α relaxation of glass-forming molecular liquids. The relaxation of domains could not be observed in the present experiment but should have relaxation times longer than 100 ns. This is the first report to clarify temperature dependence of the hierarchical structure and relaxations simultaneously for a typical ionic liquid.

  16. Hierarchically-structured silver nanoflowers for highly conductive metallic inks with dramatically reduced filler concentration.

    Science.gov (United States)

    C, Muhammed Ajmal; K P, Faseela; Singh, Swati; Baik, Seunghyun

    2016-10-07

    Silver has long been employed as an electrically conductive component, and morphology-dependent properties have been actively investigated. Here we present a novel scalable synthesis method of flower-shaped silver nanoparticles (silver nanoflowers, Ag NFs). The preferential affinity of citrate molecules on (111) surface of silver enabled spontaneous anisotropic growth of Ag NFs (bud size: 250~580 nm, single crystalline petal thickness: 9~22 nm) with high reproducibility and a high yield of >99.5%. The unique hierarchical structure resulted in coalescence of petals over 80~120 °C which was practically employed in conductive inks to construct percolation pathways among Ag NFs. The ink with only 3 wt% of Ag NFs provided two orders of magnitude greater conductivity (1.008 × 10(5) Scm(-1)), at a low curing temperature of 120 °C, compared with the silver nanoparticle ink with a much higher silver concentration (50 wt%). This extraordinary property may provide an excellent opportunity for Ag NFs for practical applications in printable and flexible electronics.

  17. Oscillatory behaviors and hierarchical assembly of contractile structures in intercalating cells

    Science.gov (United States)

    Fernandez-Gonzalez, Rodrigo; Zallen, Jennifer A.

    2011-08-01

    Fluctuations in the size of the apical cell surface have been associated with apical constriction and tissue invagination. However, it is currently not known if apical oscillatory behaviors are a unique property of constricting cells or if they constitute a universal feature of the force balance between cells in multicellular tissues. Here, we set out to determine whether oscillatory cell behaviors occur in parallel with cell intercalation during the morphogenetic process of axis elongation in the Drosophila embryo. We applied multi-color, time-lapse imaging of living embryos and SIESTA, an integrated tool for automated and semi-automated cell segmentation, tracking, and analysis of image sequences. Using SIESTA, we identified cycles of contraction and expansion of the apical surface in intercalating cells and characterized them at the molecular, cellular, and tissue scales. We demonstrate that apical oscillations are anisotropic, and this anisotropy depends on the presence of intact cell-cell junctions and spatial cues provided by the anterior-posterior patterning system. Oscillatory cell behaviors during axis elongation are associated with the hierarchical assembly and disassembly of contractile actomyosin structures at the medial cortex of the cell, with actin localization preceding myosin II and with the localization of both proteins preceding changes in cell shape. We discuss models to explain how the architecture of cytoskeletal networks regulates their contractile behavior and the mechanisms that give rise to oscillatory cell behaviors in intercalating cells.

  18. Multifunctional hybrid porous filters with hierarchical structures for simultaneous removal of indoor VOCs, dusts and microorganisms.

    Science.gov (United States)

    Zhao, Yang; Low, Ze-Xian; Feng, Shasha; Zhong, Zhaoxiang; Wang, Yong; Yao, Zhong

    2017-02-23

    Air purification often requires multiple layers of filters with different functions to remove various air pollutants, which lead to high pressure drop, high air flow path and frequent filter replacement. In this work, a novel multifunctional Ag@MWCNTs/Al2O3 hybrid filter with a depth-type hierarchical structure for simultaneous removal of fine particles, microorganisms and VOCs was designed and fabricated. The novel hybrid air filter showed leading air purification performances to date, achieving 82.24% degradation of formaldehyde at room temperature, 99.99% formaldehyde degradation at 55 °C and complete retention of indoor airborne microorganisms. The complete particle retention rate (100% retention) based on the most penetrating particle size (MPPS, aerodynamic diameter ≦300 nm) of Ag@MWCNTs/Al2O3 was achieved at an only 35.60% pressure drop compared with the pristine Al2O3 filter, leading to the highest quality factor (Qf) ever reported. Furthermore, the Ag@MWCNTs/Al2O3 hybrid filter showed excellent water repellency (water contact angle of 139.6 ± 2.9°), prolonging the service life of the filters and improving the air purification efficiency. The novel Ag@MWCNTs/Al2O3 hybrid filter exhibits remarkable air purification performance in both laboratory synthetic conditions as well as in the "real world" and shows great promise as an effective single replacement for multiple layers of air purifying filters.

  19. Stretchable conducting materials with multi-scale hierarchical structures for biomedical applications

    Science.gov (United States)

    Kim, Hyun; Shim, Bong Sup

    2014-08-01

    Electrogenetic tissues in human body such as central and peripheral nerve systems, muscular and cardiomuscular systems are soft and stretchable materials. However, most of the artificial materials, interfacing with those conductive tissues, such as neural electrodes and cardiac pacemakers, have stiff mechanical properties. The rather contradictory properties between natural and artificial materials usually cause critical incompatibility problems in implanting bodymachine interfaces for wide ranges of biomedical devices. Thus, we developed a stretchable and electrically conductive material with complex hierarchical structures; multi-scale microstructures and nanostructural electrical pathways. For biomedical purposes, an implantable polycaprolactone (PCL) membrane was coated by molecularly controlled layer-bylayer (LBL) assembly of single-walled carbon nanotubes (SWNTs) or poly(3,4-ethylenedioxythiophene) (PEDOT). The soft PCL membrane with asymmetric micro- and nano-pores provides elastic properties, while conductive SWNT or PEDOT coating preserves stable electrical conductivity even in a fully stretched state. This electrical conductivity enhanced ionic cell transmission and cell-to-cell interactions as well as electrical cellular stimulation on the membrane. Our novel stretchable conducting materials will overcome long-lasting challenges for bioelectronic applications by significantly reducing mechanical property gaps between tissues and artificial materials and by providing 3D interconnected electro-active pathways which can be available even at a fully stretched state.

  20. Interference mitigation for broadcast in hierarchical cell structure networks: Transmission strategy and area spectral efficiency

    KAUST Repository

    Yang, Yuli

    2014-10-01

    In this paper, a hierarchical cell structure (HCS) is considered, where an access point (AP) broadcasts to local nodes (LNs) over orthogonal frequency subbands within a local cell located in a macrocell. Since the local cell shares the spectrum licensed to the macrocell, a given LN is interfered with by the macrocell user (MU)\\'s transmissions over the same subband. To improve the performance of the AP\\'s broadcast service, a novel transmission strategy is proposed to mitigate the interference from the MU to the LN while achieving diversity gain. For the purpose of performance evaluation, the ergodic capacity of the proposed scheme is quantified, and the corresponding closed-form expression is obtained. By comparing with the traditional transmission scheme, which suffers from MU\\'s interference, illustrative numerical results substantiate that the proposed scheme achieves better performance than the traditional scheme as the MU-LN mean channel power gain is larger than half of the AP-LN mean channel power gain. Subsequently, we develop an optimized network design by maximizing the area spectral efficiency (ASE) of the AP\\'s broadcast in the local cell.

  1. Hierarchical structures of cactus spines that aid in the directional movement of dew droplets.

    Science.gov (United States)

    Malik, F T; Clement, R M; Gethin, D T; Kiernan, M; Goral, T; Griffiths, P; Beynon, D; Parker, A R

    2016-08-06

    Three species of cactus whose spines act as dew harvesters were chosen for this study: Copiapoa cinerea var. haseltoniana, Mammillaria columbiana subsp. yucatanensis and Parodia mammulosa and compared with Ferocactus wislizenii whose spines do not perform as dew harvesters. Time-lapse snapshots of C. cinerea showed movement of dew droplets from spine tips to their base, even against gravity. Spines emanating from one of the areoles of C. cinerea were submerged in water laced with fluorescent nanoparticles and this particular areole with its spines and a small area of stem was removed and imaged. These images clearly showed that fluorescent water had moved into the stem of the plant. Lines of vascular bundles radiating inwards from the surface areoles (from where the spines emanate) to the core of the stem were detected using magnetic resonance imaging, with the exception of F. wislizenii that does not harvest dew on its spines. Spine microstructures were examined using SEM images and surface roughness measurements (Ra and Rz) taken of the spines of C. cinerea It was found that a roughness gradient created by tapered microgrooves existed that could potentially direct surface water from a spine tip to its base.This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'.

  2. Mastering algebra retrains the visual system to perceive hierarchical structure in equations.

    Science.gov (United States)

    Marghetis, Tyler; Landy, David; Goldstone, Robert L

    2016-01-01

    Formal mathematics is a paragon of abstractness. It thus seems natural to assume that the mathematical expert should rely more on symbolic or conceptual processes, and less on perception and action. We argue instead that mathematical proficiency relies on perceptual systems that have been retrained to implement mathematical skills. Specifically, we investigated whether the visual system-in particular, object-based attention-is retrained so that parsing algebraic expressions and evaluating algebraic validity are accomplished by visual processing. Object-based attention occurs when the visual system organizes the world into discrete objects, which then guide the deployment of attention. One classic signature of object-based attention is better perceptual discrimination within, rather than between, visual objects. The current study reports that object-based attention occurs not only for simple shapes but also for symbolic mathematical elements within algebraic expressions-but only among individuals who have mastered the hierarchical syntax of algebra. Moreover, among these individuals, increased object-based attention within algebraic expressions is associated with a better ability to evaluate algebraic validity. These results suggest that, in mastering the rules of algebra, people retrain their visual system to represent and evaluate abstract mathematical structure. We thus argue that algebraic expertise involves the regimentation and reuse of evolutionarily ancient perceptual processes. Our findings implicate the visual system as central to learning and reasoning in mathematics, leading us to favor educational approaches to mathematics and related STEM fields that encourage students to adapt, not abandon, their use of perception.

  3. Dynamics of Infuence on Hierarchical Structures: Towards the Statistical Mechanics of Social Class Struggle

    CERN Document Server

    Fotouhi, Babak

    2013-01-01

    The theory of class struggle is modeled within the framework of statistical physics. Dichotomous spin dynamics on a pyramid-shaped hierarchical structure are examined (akin to the Cayley tree). A "head node" is placed at the apex. The system embodies a number of "classes", corresponding to different levels of the hierarchy. A class is comprised of nodes that are equidistant from the head. Weighted links exist between nodes from the same and different classes. We study the effect of these weights on the dynamics. The spin (hereafter, "state") of the head node is fixed, and it imposes its state on the rest of the hierarchy. Necessary conditions so that the classes eventually repudiate or acquiesce in the state imposed by the head node are found. The results show that, to reach unanimity across the hierarchy, it suffices for the head node to make the bottom-most class adopt the same state. Then the rest of the hierarchy will inevitably comply, regardless of the inter/intra class link configurations. Hence the ro...

  4. Hierarchical Structure of Abilities: Factorial Validation of Higher Order Constructs in Thurstone's Primary Mental Abilities.

    Science.gov (United States)

    Paden, Patricia

    1981-01-01

    Thurstone's primary mental abilities (1938/1968) involving 57 tests were factor analyzed to produce a comprehensive hierarchical model. Kaiser's varimax solution for primary mental abilities served as the raw data for this study. (Author/GK)

  5. Self-consistent treatment of v-groove quantum wire band structure in no parabolic approximation

    Directory of Open Access Journals (Sweden)

    Crnjanski Jasna V.

    2004-01-01

    Full Text Available The self-consistent no parabolic calculation of a V-groove-quantum-wire (VQWR band structure is presented. A comparison with the parabolic flat-band model of VQWR shows that both, the self-consistency and the nonparabolicity shift sub band edges, in some cases even in the opposite directions. These shifts indicate that for an accurate description of inter sub band absorption, both effects have to be taken into the account.

  6. Correlation between Hierarchical Structure and Processing Control of Large-area Spray-coated Polymer Solar Cells toward High Performance.

    Science.gov (United States)

    Huang, Yu-Ching; Tsao, Cheng-Si; Cha, Hou-Chin; Chuang, Chih-Min; Su, Chun-Jen; Jeng, U-Ser; Chen, Charn-Ying

    2016-01-28

    The formation mechanism of a spray-coated film is different from that of a spin-coated film. This study employs grazing incidence small- and wide-angle X-ray Scattering (GISAXS and GIWAXS, respectively) quantitatively and systematically to investigate the hierarchical structure and phase-separated behavior of a spray-deposited blend film. The formation of PCBM clusters involves mutual interactions with both the P3HT crystal domains and droplet boundary. The processing control and the formed hierarchical structure of the active layer in the spray-coated polymer/fullerene blend film are compared to those in the spin-coated film. How the different post-treatments, such as thermal and solvent vapor annealing, tailor the hierarchical structure of the spray-coated films is quantitatively studied. Finally, the relationship between the processing control and tailored BHJ structures and the performance of polymer solar cell devices is established here, taking into account the evolution of the device area from 1 × 0.3 and 1 × 1 cm(2). The formation and control of the special networks formed by the PCBM cluster and P3HT crystallites, respectively, are related to the droplet boundary. These structures are favorable for the transverse transport of electrons and holes.

  7. Correlation between Hierarchical Structure and Processing Control of Large-area Spray-coated Polymer Solar Cells toward High Performance

    Science.gov (United States)

    Huang, Yu-Ching; Tsao, Cheng-Si; Cha, Hou-Chin; Chuang, Chih-Min; Su, Chun-Jen; Jeng, U-Ser; Chen, Charn-Ying

    2016-01-01

    The formation mechanism of a spray-coated film is different from that of a spin-coated film. This study employs grazing incidence small- and wide-angle X-ray Scattering (GISAXS and GIWAXS, respectively) quantitatively and systematically to investigate the hierarchical structure and phase-separated behavior of a spray-deposited blend film. The formation of PCBM clusters involves mutual interactions with both the P3HT crystal domains and droplet boundary. The processing control and the formed hierarchical structure of the active layer in the spray-coated polymer/fullerene blend film are compared to those in the spin-coated film. How the different post-treatments, such as thermal and solvent vapor annealing, tailor the hierarchical structure of the spray-coated films is quantitatively studied. Finally, the relationship between the processing control and tailored BHJ structures and the performance of polymer solar cell devices is established here, taking into account the evolution of the device area from 1 × 0.3 and 1 × 1 cm2. The formation and control of the special networks formed by the PCBM cluster and P3HT crystallites, respectively, are related to the droplet boundary. These structures are favorable for the transverse transport of electrons and holes. PMID:26817585

  8. Scalable synthesis of hierarchically structured carbon nanotube-graphene fibres for capacitive energy storage.

    Science.gov (United States)

    Yu, Dingshan; Goh, Kunli; Wang, Hong; Wei, Li; Jiang, Wenchao; Zhang, Qiang; Dai, Liming; Chen, Yuan

    2014-07-01

    Micro-supercapacitors are promising energy storage devices that can complement or even replace batteries in miniaturized portable electronics and microelectromechanical systems. Their main limitation, however, is the low volumetric energy density when compared with batteries. Here, we describe a hierarchically structured carbon microfibre made of an interconnected network of aligned single-walled carbon nanotubes with interposed nitrogen-doped reduced graphene oxide sheets. The nanomaterials form mesoporous structures of large specific surface area (396 m(2) g(-1)) and high electrical conductivity (102 S cm(-1)). We develop a scalable method to continuously produce the fibres using a silica capillary column functioning as a hydrothermal microreactor. The resultant fibres show a specific volumetric capacity as high as 305 F cm(-3) in sulphuric acid (measured at 73.5 mA cm(-3) in a three-electrode cell) or 300 F cm(-3) in polyvinyl alcohol (PVA)/H(3)PO(4) electrolyte (measured at 26.7 mA cm(-3) in a two-electrode cell). A full micro-supercapacitor with PVA/H(3)PO(4) gel electrolyte, free from binder, current collector and separator, has a volumetric energy density of ∼6.3 mWh cm(-3) (a value comparable to that of 4 V-500 µAh thin-film lithium batteries) while maintaining a power density more than two orders of magnitude higher than that of batteries, as well as a long cycle life. To demonstrate that our fibre-based, all-solid-state micro-supercapacitors can be easily integrated into miniaturized flexible devices, we use them to power an ultraviolet photodetector and a light-emitting diode.

  9. Scalable synthesis of hierarchically structured carbon nanotube-graphene fibres for capacitive energy storage

    Science.gov (United States)

    Yu, Dingshan; Goh, Kunli; Wang, Hong; Wei, Li; Jiang, Wenchao; Zhang, Qiang; Dai, Liming; Chen, Yuan

    2014-07-01

    Micro-supercapacitors are promising energy storage devices that can complement or even replace batteries in miniaturized portable electronics and microelectromechanical systems. Their main limitation, however, is the low volumetric energy density when compared with batteries. Here, we describe a hierarchically structured carbon microfibre made of an interconnected network of aligned single-walled carbon nanotubes with interposed nitrogen-doped reduced graphene oxide sheets. The nanomaterials form mesoporous structures of large specific surface area (396 m2 g-1) and high electrical conductivity (102 S cm-1). We develop a scalable method to continuously produce the fibres using a silica capillary column functioning as a hydrothermal microreactor. The resultant fibres show a specific volumetric capacity as high as 305 F cm-3 in sulphuric acid (measured at 73.5 mA cm-3 in a three-electrode cell) or 300 F cm-3 in polyvinyl alcohol (PVA)/H3PO4 electrolyte (measured at 26.7 mA cm-3 in a two-electrode cell). A full micro-supercapacitor with PVA/H3PO4 gel electrolyte, free from binder, current collector and separator, has a volumetric energy density of ~6.3 mWh cm-3 (a value comparable to that of 4 V-500 µAh thin-film lithium batteries) while maintaining a power density more than two orders of magnitude higher than that of batteries, as well as a long cycle life. To demonstrate that our fibre-based, all-solid-state micro-supercapacitors can be easily integrated into miniaturized flexible devices, we use them to power an ultraviolet photodetector and a light-emitting diode.

  10. Are watershed and lacustrine controls on planktonic N2 fixation hierarchically structured?

    Science.gov (United States)

    Scott, J Thad; Doyle, Robert D; Prochnow, Shane J; White, Joseph D

    2008-04-01

    N2 fixation can be an important source of N to limnetic ecosystems and can influence the structure of phytoplankton communities. However, watershed-scale conditions that favor N2 fixation in lakes and reservoirs have not been well studied. We measured N2 fixation and lacustrine variables monthly over a 19-month period in Waco Reservoir, Texas, USA, and linked these data with nutrient-loading estimates from a physically based watershed model. Readily available topographic, soil, land cover, effluent discharge, and climate data were used in the Soil and Water Assessment Tool (SWAT) to derive watershed nutrient-loading estimates. Categorical and regression tree (CART) analysis revealed that lacustrine and watershed correlates of N2 fixation were hierarchically structured. Lacustrine conditions showed greater predictive capability temporally. For instance, low NO3(-) concentration (27 degrees C) in the reservoir were correlated with the initiation of N2 fixation seasonally. When lacustrine conditions were favorable for N2 fixation, watershed conditions appeared to influence spatial patterns of N2 fixation within the reservoir. For example, spatially explicit patterns of N2 fixation were correlated with the ratio of N:P in nutrient loadings and the N loading rate, which were driven by anthropogenic activity in the watershed and periods of low stream flow, respectively. Although N2 fixation contributed <5% of the annual N load to the reservoir, 37% of the N load was derived from atmospheric N2 fixation during summertime when stream flow in the watershed was low. This study provides evidence that watershed anthropogenic activity can exert control on planktonic N2 fixation, but that temporality is controlled by lacustrine conditions. Furthermore, this study also supports suggestions that reduced inflows may increase the propensity of N2-fixing cyanobacterial blooms in receiving waters of anthropogenically modified landscapes.

  11. Energetics and electronic structure of nanoscale rotors consisting of triptycene and hydrocarbon molecules

    Science.gov (United States)

    Akiba, Miki; Okada, Susumu

    2017-10-01

    Using the density functional theory with generalized gradient approximation, we studied the energetics and electronic structures of nanoscale rotors consisting of tryptycene and hydrocarbon molecules with respect to their mutual orientation. Energy barriers for the rotational motion of an attached hydrocarbon molecule range from 40 to 200 meV, depending on the attached molecular species and arrangements. The electronic structure of the nanoscale molecular rotors does not depend on the rotational angle of the attached hydrocarbon molecules.

  12. Organosilane with gemini-type structure as the mesoporogen for synthesis of hierarchical porous ZSM-5 zeolite

    KAUST Repository

    Zhu, Haibo

    2016-02-08

    A new kind of organosilane (1,6-bis (diethyl(3-trimethoxysilylpropyl)ammonium) hexane bromide) with a gemini-type structure was prepared and used as a mesoporogen for the synthesis of hierarchical porous ZSM-5 zeolite. There are two quaternary ammonium centers along with double hydrolysable -RSi(OMe)3 fragments in the organosilane, which results in a strong interaction between this mesoporogen and silica-alumina gel. The organosilane can be easily incorporated into ZSM-5 zeolite structure during the crystallization process, and it was finally removed by calcination leading to secondary pores in ZSM-5. The synthesized ZSM-5 has been systematically studied by XRD, nitrogen adsorption, SEM, TEM, TG and solid-state one-dimensional (1D) and two-dimensional (2D) NMR, which reveals information on its detailed structure. It has a hierarchical porosity system, which combines the intrinsic micropores coming from the crystalline structure and irregular mesopores created by the organosilane template. Moreover, the mesoposity including pore size and volume within ZSM-5 can be systematically tuned by changing the organosilane/TEOS ratios, which confirms this organosilane has high flexibility of using as template for the synthesis of hierarchical porous zeolite.

  13. Hierarchical folding of multiple sequence alignments for the prediction of structures and RNA-RNA interactions

    Directory of Open Access Journals (Sweden)

    Gorodkin Jan

    2010-05-01

    Full Text Available Abstract Background Many regulatory non-coding RNAs (ncRNAs function through complementary binding with mRNAs or other ncRNAs, e.g., microRNAs, snoRNAs and bacterial sRNAs. Predicting these RNA interactions is essential for functional studies of putative ncRNAs or for the design of artificial RNAs. Many ncRNAs show clear signs of undergoing compensating base changes over evolutionary time. Here, we postulate that a non-negligible part of the existing RNA-RNA interactions contain preserved but covarying patterns of interactions. Methods We present a novel method that takes compensating base changes across the binding sites into account. The algorithm works in two steps on two pre-generated multiple alignments. In the first step, individual base pairs with high reliability are found using the PETfold algorithm, which includes evolutionary and thermodynamic properties. In step two (where high reliability base pairs from step one are constrained as unpaired, the principle of cofolding is combined with hierarchical folding. The final prediction of intra- and inter-molecular base pairs consists of the reliabilities computed from the constrained expected accuracy scoring, which is an extended version of that used for individual multiple alignments. Results We derived a rather extensive algorithm. One of the advantages of our approach (in contrast to other RNA-RNA interaction prediction methods is the application of covariance detection and prediction of pseudoknots between intra- and inter-molecular base pairs. As a proof of concept, we show an example and discuss the strengths and weaknesses of the approach.

  14. Unsupervised Learning of Structural Representation of Percussive Audio Using a Hierarchical Dirichlet Process Hidden Markov Model

    DEFF Research Database (Denmark)

    Antich, Jose Luis Diez; Paterna, Mattia; Marxer, Richard

    2016-01-01

    A method is proposed that extracts a structural representation of percussive audio in an unsupervised manner. It consists of two parts: 1) The input signal is segmented into blocks of approximately even duration, aligned to a metrical grid, using onset and timbre feature extraction, agglomerative...

  15. Hierarchical structure and modules in the Escherichia coli transcriptional regulatory network revealed by a new top-down approach

    Directory of Open Access Journals (Sweden)

    Buer Jan

    2004-12-01

    Full Text Available Abstract Background Cellular functions are coordinately carried out by groups of genes forming functional modules. Identifying such modules in the transcriptional regulatory network (TRN of organisms is important for understanding the structure and function of these fundamental cellular networks and essential for the emerging modular biology. So far, the global connectivity structure of TRN has not been well studied and consequently not applied for the identification of functional modules. Moreover, network motifs such as feed forward loop are recently proposed to be basic building blocks of TRN. However, their relationship to functional modules is not clear. Results In this work we proposed a top-down approach to identify modules in the TRN of E. coli. By studying the global connectivity structure of the regulatory network, we first revealed a five-layer hierarchical structure in which all the regulatory relationships are downward. Based on this regulatory hierarchy, we developed a new method to decompose the regulatory network into functional modules and to identify global regulators governing multiple modules. As a result, 10 global regulators and 39 modules were identified and shown to have well defined functions. We then investigated the distribution and composition of the two basic network motifs (feed forward loop and bi-fan motif in the hierarchical structure of TRN. We found that most of these network motifs include global regulators, indicating that these motifs are not basic building blocks of modules since modules should not contain global regulators. Conclusion The transcriptional regulatory network of E. coli possesses a multi-layer hierarchical modular structure without feedback regulation at transcription level. This hierarchical structure builds the basis for a new and simple decomposition method which is suitable for the identification of functional modules and global regulators in the transcriptional regulatory network of E

  16. Locally self-consistent Green’s function approach to the electronic structure problem

    DEFF Research Database (Denmark)

    Abrikosov, I.A.; Simak, S.I.; Johansson, B.;

    1997-01-01

    The locally self-consistent Green's function (LSGF) method is an order-N method for calculation of the electronic structure of systems with an arbitrary distribution of atoms of different kinds on an underlying crystal lattice. For each atom Dyson's equation is used to solve the electronic multiple...

  17. Controllable preparation of hierarchically core–shell structure NiO/C microspheres for non-enzymatic glucose sensor

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Zhenzhen; Yin, Haoyong; Nie, Qiulin, E-mail: nieqiulin@hdu.edu.cn

    2015-05-25

    Highlights: • Hierarchically core–shell structure NiO/C microspheres were prepared. • The NiO/C microspheres were obtained via layer-by-layer assembly methods. • The NiO/C sensor shows excellent performance in glucose detection. • Good stability and anti-interference were also obtained on the NiO/C sensor. - Abstract: Hierarchically core–shell structure NiO/C microspheres were controllably fabricated with a facile hydrothermal method via layer-by-layer assembly. The single-/double-/triple-/quadri-shelled NiO/C microspheres were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX). The results showed that the NiO/C composites are flower-like hierarchically structured microspheres composed of the interconnecting porous nanoplates with the thickness of about 50 nm. Every nanoplate is assembled by NiO nanoparticles with diameter about 10 nm. All the multi-shelled NiO/C microspheres show high electro-catalytic activity toward the oxidation of glucose. The double-shelled NiO/C glucose sensor exhibits the best performance with a much wider linear range of 2 μM–1.279 mM, higher sensitivity of 30.19 mA mM{sup −1} cm{sup −2} and lower detection limit of 2 μM. Importantly, long-term stability and favorable anti-interference were obtained thanks to the hierarchically core–shell structure.

  18. APPLICATION OF NEURAL NETWORK WITH MULTI-HIERARCHIC STRUCTURE TO EVALUATE SUSTAINABLE DEVELOPMENT OF THE COAL MINES

    Institute of Scientific and Technical Information of China (English)

    李新春; 陶学禹

    2000-01-01

    The neural network with multi-hierarchic structure is provided in this paper to evaluate sustainable development of the coal mines based on analyzing its effect factors. The whole evaluating system is composed of 5 neural networks.The feasibility of this method has been proved by case study. This study will provide a scientfic and theoretic foundation for evaluating the sustainable development of coal mines.

  19. A High-Transmission, Multiple Antireflective Surface Inspired from Bilayer 3D Ultrafine Hierarchical Structures in Butterfly Wing Scales.

    Science.gov (United States)

    Han, Zhiwu; Mu, Zhengzhi; Li, Bo; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

    2016-02-10

    A high-transmission, multiple antireflective surface inspired by bilayer 3D ultrafine hierarchical structures in butterfly wing scales is fabricated on a glass substrate using wet chemical biomimetic fabrication. Interestingly, the biomimetic antireflective surface exhibits excellent antireflective properties and high transmission, which provides better characteristics than the butterfly wings and can significantly reduce reflection without losing transparency. These findings offer a new path for generating nanostructured antireflectors with high transmission properties.

  20. Hydrothermal deposition and photochromic performances of three kinds of hierarchical structure arrays of WO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Defang; Shen, Yi, E-mail: sysy7373@163.com; Ouyang, Yali; Li, Zhen

    2012-10-01

    Three kinds of tungsten oxide (WO{sub 3}) thin films have been fabricated by a simple hydrothermal deposition method. Scanning electron microscopy images of the products revealed that the capping agents did impact the microstructure of WO{sub 3} films. Films prepared without capping agents were ordered nanorod arrays, while the ones obtained with ethanol and oxalic acid revealed peeled-orange-like and cauliflower-like hierarchical structure arrays, respectively. Both of the two hierarchical structures were composed of much thinner nanorods compared with the one obtained without capping agents. All the WO{sub 3} films exhibited good photochromic properties and the two with inducers performed even better, which could be due to the changes in the microstructure that increased the amount of photogenerated electron-hole pairs and the proton diffusion rates. - Highlights: Black-Right-Pointing-Pointer Ordered WO{sub 3} nanorod arrays were prepared by hydrothermal deposition process. Black-Right-Pointing-Pointer Two hierarchical WO{sub 3} structure arrays were obtained with ethanol and oxalic acid. Black-Right-Pointing-Pointer Mechanism for the improved photochromic performances of WO{sub 3} films is proposed.

  1. Impact of cell shape in hierarchically structured plant surfaces on the attachment of male Colorado potato beetles (Leptinotarsa decemlineata

    Directory of Open Access Journals (Sweden)

    Bettina Prüm

    2012-01-01

    Full Text Available Plant surfaces showing hierarchical structuring are frequently found in plant organs such as leaves, petals, fruits and stems. In our study we focus on the level of cell shape and on the level of superimposed microstructuring, leading to hierarchical surfaces if both levels are present. While it has been shown that epicuticular wax crystals and cuticular folds strongly reduce insect attachment, and that smooth papillate epidermal cells in petals improve the grip of pollinators, the impact of hierarchical surface structuring of plant surfaces possessing convex or papillate cells on insect attachment remains unclear. We performed traction experiments with male Colorado potato beetles on nine different plant surfaces with different structures. The selected plant surfaces showed epidermal cells with either tabular, convex or papillate cell shape, covered either with flat films of wax, epicuticular wax crystals or with cuticular folds. On surfaces possessing either superimposed wax crystals or cuticular folds we found traction forces to be almost one order of magnitude lower than on surfaces covered only with flat films of wax. Independent of superimposed microstructures we found that convex and papillate epidermal cell shapes slightly enhance the attachment ability of the beetles. Thus, in plant surfaces, cell shape and superimposed microstructuring yield contrary effects on the attachment of the Colorado potato beetle, with convex or papillate cells enhancing attachment and both wax crystals or cuticular folds reducing attachment. However, the overall magnitude of traction force mainly depends on the presence or absence of superimposed microstructuring.

  2. Ab initio self-consistent x-ray absorption fine structure analysis for metalloproteins.

    Science.gov (United States)

    Dimakis, Nicholas; Bunker, Grant

    2006-12-01

    X-ray absorption fine structure is a powerful tool for probing the structures of metals in proteins in both crystalline and noncrystalline environments. Until recently, a fundamental problem in biological XAFS has been that ad hoc assumptions must be made concerning the vibrational properties of the amino acid residues that are coordinated to the metal to fit the data. Here, an automatic procedure for accurate structural determination of active sites of metalloproteins is presented. It is based on direct multiple-scattering simulation of experimental X-ray absorption fine structure spectra combining electron multiple scattering calculations with density functional theory calculations of vibrational modes of amino acid residues and the genetic algorithm differential evolution to determine a global minimum in the space of fitting parameters. Structure determination of the metalloprotein active site is obtained through a self-consistent iterative procedure with only minimal initial information.

  3. Osteogenic activity of titanium surfaces with hierarchical micro-/nano-structures obtained by hydrofluoric acid treatment

    Science.gov (United States)

    Liang, Jianfei; Xu, Shanshan; Shen, Mingming; Cheng, Bingkun; Li, Yongfeng; Liu, Xiangwei; Qin, Dongze; Bellare, Anuj; Kong, Liang

    2017-01-01

    An easier method for constructing the hierarchical micro-/nano-structures on the surface of dental implants in the clinic is needed. In this study, three different titanium surfaces with microscale grooves (width 0.5–1, 1–1.5, and 1.5–2 μm) and nanoscale nanoparticles (diameter 20–30, 30–50, and 50–100 nm, respectively) were obtained by treatment with different concentrations of hydrofluoric acid (HF) and at different etching times (1%, 3 min; 0.5%, 12 min; and 1.5%, 12 min, respectively; denoted as groups HF1, HF2, and HF3). The biological response to the three different titanium surfaces was evaluated by in vitro human bone marrow-derived mesenchymal stem cell (hBMMSC) experiments and in vivo animal experiments. The results showed that cell adhesion, proliferation, alkaline phosphatase activity, and mineralization of hBMMSCs were increased in the HF3 group. After the different surface implants were inserted into the distal femurs of 40 rats, the bone–implant contact in groups HF1, HF2, and HF3 was 33.17%±2.2%, 33.82%±3.42%, and 41.04%±3.08%, respectively. Moreover, the maximal pullout force in groups HF1, HF2, and HF3 was 57.92±2.88, 57.83±4.09, and 67.44±6.14 N, respectively. The results showed that group HF3 with large micron grooves (1.5–2.0 μm) and large nanoparticles (50–100 nm) showed the best bio-functionality for the hBMMSC response and osseointegration in animal experiments compared with other groups.

  4. Using light to guide the motion of nanorods in photoresponsive binary blends: designing hierarchically structured nanocomposites.

    Science.gov (United States)

    Liu, Ya; Kuksenok, Olga; Balazs, Anna C

    2013-10-15

    One of the challenges in creating high-performance polymer nanocomposites is establishing effective routes for tailoring the morphology of both the polymer mixture and the dispersed nanoparticles, which contribute desirable optical, electrical, and mechanical properties. Using computational modeling, we devise an effective method for simultaneously controlling the spatial regularity of the polymer phases and the distribution of the rods within this matrix. We focus on mixtures of photosensitive AB binary blends and A-coated nanorods; in the presence of light, the binary blends undergo a reversible chemical reaction and phase separation to yield a morphology resembling that of microphase-separated diblock copolymers. We simulate the effects of illuminating this sample with a uniform background light and a higher intensity, spatially localized light, which is rastered over the sample with a velocity v. The resulting material displays a periodically ordered, essentially defect-free morphology, with the A-like nanoparticles localized in lamellar A domains. The dynamic behavior of the rods within this system can be controlled by varying the velocity v and Γ2, the reaction rate coefficient produced by the higher intensity light. Specifically, the rastering light can drive the rods to be "pushed" along the lamellar domains or oriented perpendicular to these stripes. Given these attributes, we isolate scenarios where the system encompasses a complex hierarchical structure, with rods that are simultaneously ordered along two distinct directions within the periodic matrix. Namely, the rods form long nanowires that span the length of the sample and lie perpendicular to these wires in regularly spaced A lamellae. Hence, our approach points to new routes for producing self-organized rectangular grids, which can impart remarkable optoelectronic or mechanical properties to the materials.

  5. Phase-Controlled Iron Oxide Nanobox Deposited on Hierarchically Structured Graphene Networks for Lithium Ion Storage and Photocatalysis

    Science.gov (United States)

    Yun, Sol; Lee, Young-Chul; Park, Ho Seok

    2016-01-01

    The phase control, hierarchical architecturing and hybridization of iron oxide is important for achieving multifunctional capability for many practical applications. Herein, hierarchically structured reduced graphene oxide (hrGO)/α-Fe2O3 and γ-Fe3O4 nanobox hybrids (hrGO/α-Fe and hrGO/γ-Fe NBhs) are synthesized via a one-pot, hydrothermal process and their functionality controlled by the crystalline phases is adapted for energy storage and photocatalysis. The three-dimensionally (3D) macroporous structure of hrGO/α-Fe NBhs is constructed, while α-Fe2O3 nanoboxes (NBs) in a proximate contact with the hrGO surface are simultaneously grown during a hydrothermal treatment. The discrete α-Fe2O3 NBs are uniformly distributed on the surface of the hrGO/α-Fe and confined in the 3D architecture, thereby inhibiting the restacking of rGO. After the subsequent phase transition into γ-Fe3O4, the hierarchical structure and the uniform distribution of NBs are preserved. Despite lower initial capacity, the hrGO/α-Fe NBhs show better rate and cyclic performances than those of commercial rGO/α-Fe due to the uniform distribution of discrete α-Fe2O3 NBs and electronic conductivity, macroporosity, and buffering effect of the hrGO for lithium ion battery anodes. Moreover, the catalytic activity and kinetics of hrGO/γ-Fe NBhs are enhanced for photo-Fenton reaction because of the uniform distribution of discrete γ-Fe3O4 NBs on the 3D hierarchical architecture.

  6. Three-dimensional nanotube electrode arrays for hierarchical tubular structured high-performance pseudocapacitors

    Science.gov (United States)

    Gao, Yuan; Lin, Yuanjing; Chen, Jiaqi; Lin, Qingfeng; Wu, Yue; Su, Wenjun; Wang, Wenli; Fan, Zhiyong

    2016-07-01

    Ordered three-dimensional (3-D) tubular arrays are highly attractive candidates for high performance pseudocapacitor electrodes. Here, we report 3-D fluorine doped tin oxide (FTO) tubular arrays fabricated by a cost-effective ultrasonic spray pyrolysis (USP) method in anodic aluminum oxide (AAO) channels with high uniformity. The large surface area of such a structure leads to remarkable surface area enhancement up to 51.8 times compared to a planar structure. Combining with electrochemically deposited manganese dioxide (MnO2) nanoflakes on the inner side wall of the FTO nanotubes, the unique hierarchical tubular structured pseudocapacitor electrode demonstrated the highest areal capacitance of 193.8 mF cm-2 at the scan rate of 5 mV s-1 and 184 mF cm-2 at the discharge current density of 0.6 mA cm-2, which is 18.5 times that of a planar electrode. And it also showed a volumetric capacitance of 112.6 F cm-3 at the scan rate of 5 mV s-1 and 108.8 F cm-3 at the discharge current density of 0.6 mA cm-2. In addition, the cyclic stability test also indicated that a nanostructured pseudocapacitive electrode has a much larger capacitance retention after 3000 cycles of the charge-discharge process compared with a planar electrode, primarily due to the mechanical stability of the nanostructure. Moreover, pseudocapacitor device fabrication based on such electrodes shows the volumetric capacitance of 17.5 F cm-3, and the highest specific energy of 1.56 × 10-3 Wh cm-3. With the merit of facile fabrication procedures and largely enhanced electrochemical performance, such a 3-D structure has high potency for energy storage systems for a wide range of practical applications.Ordered three-dimensional (3-D) tubular arrays are highly attractive candidates for high performance pseudocapacitor electrodes. Here, we report 3-D fluorine doped tin oxide (FTO) tubular arrays fabricated by a cost-effective ultrasonic spray pyrolysis (USP) method in anodic aluminum oxide (AAO) channels with

  7. On the Lagrangian structure of 3D consistent systems of asymmetric quad-equations

    CERN Document Server

    Boll, Raphael

    2011-01-01

    Recently, the first-named author gave a classification of 3D consistent 6-tuples of quad-equations with the tetrahedron property; several novel asymmetric 6-tuples have been found. Due to 3D consistency, these 6-tuples can be extended to discrete integrable systems on Z^m. We establish Lagrangian structures and flip-invariance of the action functional for the class of discrete integrable systems involving equations for which some of the biquadratics are non-degenerate and some are degenerate. This class covers, among others, some of the above mentioned novel systems.

  8. Multiscale approach to description of deformation and fracture of brittle media with hierarchical porous structure on the basis of movable cellular automaton method

    Directory of Open Access Journals (Sweden)

    S. G. Psakhie

    2013-04-01

    Full Text Available An approach to multiscale description of deformation and fracture of brittle porous materials on the basis of movable cellular automaton method was proposed. The material characterized by pore size distribution function having two maxima was considered. The core of the proposed approach consists in finding the automaton effective response function by means of direct numerical simulation of representative volume of the porous material. A hierarchical two-scale model of mechanical behavior of ceramics under compression and shear loading was developed. Zirconia based ceramics with pore size greater than the average grain size was considered. At the first scale of the model only small pores (corresponding to the first maximum of the pore size distribution function were taking into account explicitly (by removing automata from the initial structure. The representative volume and effective elastic properties of the porous material at this scale were evaluated. At the second scale of the model, big pores were taking into account explicitly, the parameters of the matrix corresponded to the ones determined at the first scale. Simulation results showed that the proposed multiscale model allows qualitatively and quantitatively correct describing of deformation and fracture of brittle material with hierarchical porous structure.

  9. Hierarchical α-Fe2O3/NiO composites with a hollow structure for a gas sensor.

    Science.gov (United States)

    Wang, Chen; Cheng, Xiaoyang; Zhou, Xin; Sun, Peng; Hu, Xiaolong; Shimanoe, Kengo; Lu, Geyu; Yamazoe, Noboru

    2014-08-13

    Hierarchical α-Fe2O3/NiO composites with a hollow nanostructure were synthesized by a facile hydrothermal method. The structures and morphologies of the composites were investigated by different kinds of techniques, including X-ray diffraction, field-emission electron scanning microscopy, transmission electron microscopy, and energy dispersive spectroscopy. Hierarchical α-Fe2O3/NiO composites were fabricated by growing the α-Fe2O3 nanorods on the surfaces of porous NiO nanosheets with a thickness of ∼12 nm. The gas sensing properties of hierarchical α-Fe2O3/NiO composites toward toluene were investigated using a static system. The response of α-Fe2O3/NiO composites to 100 ppm toluene was ∼18.68, which was 13.18 times higher than that of pure NiO at 300 °C. The enhanced response can be attributed to heterojunction. Meanwhile, the rapid response and recovery characteristics were observed because of the porous hollow structural characteristics and catalytic actions of α-Fe2O3 and NiO.

  10. Circumpolar Arctic vegetation: a hierarchic review and roadmap toward an internationally consistent approach to survey, archive and classify tundra plot data

    Science.gov (United States)

    Walker, D. A.; Daniëls, F. J. A.; Alsos, I.; Bhatt, U. S.; Breen, A. L.; Buchhorn, M.; Bültmann, H.; Druckenmiller, L. A.; Edwards, M. E.; Ehrich, D.; Epstein, H. E.; Gould, W. A.; Ims, R. A.; Meltofte, H.; Raynolds, M. K.; Sibik, J.; Talbot, S. S.; Webber, P. J.

    2016-05-01

    Satellite-derived remote-sensing products are providing a modern circumpolar perspective of Arctic vegetation and its changes, but this new view is dependent on a long heritage of ground-based observations in the Arctic. Several products of the Conservation of Arctic Flora and Fauna are key to our current understanding. We review aspects of the PanArctic Flora, the Circumpolar Arctic Vegetation Map, the Arctic Biodiversity Assessment, and the Arctic Vegetation Archive (AVA) as they relate to efforts to describe and map the vegetation, plant biomass, and biodiversity of the Arctic at circumpolar, regional, landscape and plot scales. Cornerstones for all these tools are ground-based plant-species and plant-community surveys. The AVA is in progress and will store plot-based vegetation observations in a public-accessible database for vegetation classification, modeling, diversity studies, and other applications. We present the current status of the Alaska Arctic Vegetation Archive (AVA-AK), as a regional example for the panarctic archive, and with a roadmap for a coordinated international approach to survey, archive and classify Arctic vegetation. We note the need for more consistent standards of plot-based observations, and make several recommendations to improve the linkage between plot-based observations biodiversity studies and satellite-based observations of Arctic vegetation.

  11. Structural consistency analysis of recombinant and wild-type human serum albumin

    Science.gov (United States)

    Cao, Hui-Ling; Sun, Li-Hua; Liu, Li; Li, Jian; Tang, Lin; Guo, Yun-Zhu; Mei, Qi-Bing; He, Jian-Hua; Yin, Da-Chuan

    2017-01-01

    Recombinant human serum albumin (rHSA) is potential alternatives for human serum albumin (HSA) which may ease severe shortage of HSA worldwide. In theory, rHSA and HSA are the same. Structure decides function. Therefore, the 3D structural consistency analysis of rHSA and HSA is outmost importance, which is the base of their function consistency. In this paper, the crystal structures of rHSA at resolution limit of 2.22 Å and HSA at 2.30 Å were determined by X-ray diffraction (XRD), which were deposited in the Protein Data Bank (PDB) with accession codes 4G03 (rHSA) and 4G04 (HSA). The differences between rHSA and HSA were systematically analyzed from the crystallization behavior, diffraction data and three-dimensional (3D) structure. The superimposed contrasted analysis indicated that rHSA and HSA achieved a structural similarity of 99% with an r.m.s. deviation of 0.397 Å for the corresponding overall Cα atoms. In addition, the number of α-helices in the rHSA or HSA molecule was verified to be 30. As a result, rHSA can potentially replace HSA. The study provides a theoretical and experimental basis for the clinical and additional applications of rHSA. Meanwhile, it is also a good example for applications of genetic engineering.

  12. Non-zero density-velocity consistency relations for large scale structures

    CERN Document Server

    Rizzo, Luca Alberto; Valageas, Patrick

    2016-01-01

    We present exact kinematic consistency relations for cosmological structures that do not vanish at equal times and can thus be measured in surveys. These rely on cross-correlations between the density and velocity, or momentum, fields. Indeed, the uniform transport of small-scale structures by long wavelength modes, which cannot be detected at equal times by looking at density correlations only, gives rise to a shift in the amplitude of the velocity field that could be measured. These consistency relations only rely on the weak equivalence principle and Gaussian initial conditions. They remain valid in the non-linear regime and for biased galaxy fields. They can be used to constrain non-standard cosmological scenarios or the large-scale galaxy bias.

  13. Internal consistency and factor structure of 12-item general health questionnaire in visually impaired students

    Directory of Open Access Journals (Sweden)

    Ajay Kumar Bakhla

    2013-01-01

    Full Text Available Background: As there are no instruments to measure psychological wellness or distress in visually impaired students, we studied internal consistency and factor structure of GHQ-12 in visually impaired children. Materials and Methods: Internal consistency analysis (Cronbach′s alpha and item total correlation and exploratory factor analysis (principal component analysis were carried out to identify factor structure of 12-item general health questionnaire (GHQ-12. Results: All items of GHQ-12 were significantly associated with each other and the Cronbach′s alpha coefficient for the scale was 0.7. On analysis of principal component, three-factor solution was found that accounted for 47.92% of the total variance. The factors included, ′general well-being′, ′depression′ and ′cognitive′, with Cronbach′s alpha coefficients being 0.70, 0.59, and 0.34, respectively. Conclusion: Our study findings suggest GHQ-12 is a reliable with adequate internal consistency scale and multidimensional factor structure in visually impaired students.

  14. Determination of Protein Folding Intermediate Structures Consistent with Data from Oxidative Footprinting Mass Spectrometry.

    Science.gov (United States)

    Heinkel, Florian; Gsponer, Jörg

    2016-01-29

    The mapping of folding landscapes remains an important challenge in protein chemistry. Pulsed oxidative labeling of exposed residues and their detection via mass spectrometry provide new means of taking time-resolved "snapshots" of the structural changes that occur during protein folding. However, such experiments have been so far only interpreted qualitatively. Here, we report the detailed structural interpretation of mass spectrometry data from fast photochemical oxidation of proteins (FPOP) experiments at atomic resolution in a biased molecular dynamics approach. We are able to calculate structures of the early folding intermediate of the model system barstar that are fully consistent with FPOP data and Φ values. Furthermore, structures calculated with both FPOP data and Φ values are significantly less compact and have fewer helical residues than intermediate structures calculated with Φ values only. This improves the agreement with the experimental β-Tanford value and CD measurements. The restraints that we introduce facilitate the structural interpretation of FPOP data and provide new means for refined structure calculations of transiently sampled states on protein folding landscapes.

  15. RNA secondary structure modeling at consistent high accuracy using differential SHAPE.

    Science.gov (United States)

    Rice, Greggory M; Leonard, Christopher W; Weeks, Kevin M

    2014-06-01

    RNA secondary structure modeling is a challenging problem, and recent successes have raised the standards for accuracy, consistency, and tractability. Large increases in accuracy have been achieved by including data on reactivity toward chemical probes: Incorporation of 1M7 SHAPE reactivity data into an mfold-class algorithm results in median accuracies for base pair prediction that exceed 90%. However, a few RNA structures are modeled with significantly lower accuracy. Here, we show that incorporating differential reactivities from the NMIA and 1M6 reagents--which detect noncanonical and tertiary interactions--into prediction algorithms results in highly accurate secondary structure models for RNAs that were previously shown to be difficult to model. For these RNAs, 93% of accepted canonical base pairs were recovered in SHAPE-directed models. Discrepancies between accepted and modeled structures were small and appear to reflect genuine structural differences. Three-reagent SHAPE-directed modeling scales concisely to structurally complex RNAs to resolve the in-solution secondary structure analysis problem for many classes of RNA.

  16. Improving Heat Transfer at the Bottom of Vials for Consistent Freeze Drying with Unidirectional Structured Ice.

    Science.gov (United States)

    Rosa, Mónica; Tiago, João M; Singh, Satish K; Geraldes, Vítor; Rodrigues, Miguel A

    2016-10-01

    The quality of lyophilized products is dependent of the ice structure formed during the freezing step. Herein, we evaluate the importance of the air gap at the bottom of lyophilization vials for consistent nucleation, ice structure, and cake appearance. The bottom of lyophilization vials was modified by attaching a rectified aluminum disc with an adhesive material. Freezing was studied for normal and converted vials, with different volumes of solution, varying initial solution temperature (from 5°C to 20°C) and shelf temperature (from -20°C to -40°C). The impact of the air gap on the overall heat transfer was interpreted with the assistance of a computational fluid dynamics model. Converted vials caused nucleation at the bottom and decreased the nucleation time up to one order of magnitude. The formation of ice crystals unidirectionally structured from bottom to top lead to a honeycomb-structured cake after lyophilization of a solution with 4% mannitol. The primary drying time was reduced by approximately 35%. Converted vials that were frozen radially instead of bottom-up showed similar improvements compared with normal vials but very poor cake quality. Overall, the curvature of the bottom of glass vials presents a considerable threat to consistency by delaying nucleation and causing radial ice growth. Rectifying the vials bottom with an adhesive material revealed to be a relatively simple alternative to overcome this inconsistency.

  17. Bioinspired synthesis of hierarchically micro/nano-structured CuI tetrahedron and its potential application as adsorbent for Cd(II) with high removal capacity.

    Science.gov (United States)

    Gao, Shuyan; Yang, Jianmao; Li, Zhengdao; Jia, Xiaoxia; Chen, Yanli

    2012-04-15

    An environment friendly bioinspired strategy for synthesizing hierarchically micro/nano-structured CuI tetrahedron has been developed by combining the stabilization and the reduction performances of l-tryptophan together. A possible growth mechanism of such hierarchical tetrahedron is tentatively proposed. Remarkably, such CuI tetrahedron is found to possess high removal capacity for poisonous Cd(II) ions, 136.3mg/g, and ideal reusability. This is ascribed to the hierarchical micro/nano-structure and chemical adsorption mechanism, which shows great advantages over the traditional nano-scaled adsorbents. These interesting results stand out the promising applications of such hierarchically micro/nano-structured materials in environment. It is also a good example for the organic combination of green chemistry and nanotechnologies for the treatment of contaminated water.

  18. Boron carbide: Consistency of components, lattice parameters, fine structure and chemical composition makes the complex structure reasonable

    Science.gov (United States)

    Werheit, Helmut

    2016-10-01

    The complex, highly distorted structure of boron carbide is composed of B12 and B11C icosahedra and CBC, CBB and B□B linear elements, whose concentration depends on the chemical composition each. These concentrations are shown to be consistent with lattice parameters, fine structure data and chemical composition. The respective impacts on lattice parameters are estimated and discussed. Considering the contributions of the different structural components to the energy of the overall structure makes the structure and its variation within the homogeneity range reasonable; in particular that of B4.3C representing the carbon-rich limit of the homogeneity range. Replacing in B4.3C virtually the B□B components by CBC yields the hypothetical moderately distorted B4.0C (structure formula (B11C)CBC). The reduction of lattice parameters related is compatible with recently reported uncommonly prepared single crystals, whose compositions deviate from B4.3C.

  19. Mussel-inspired one-step copolymerization to engineer hierarchically structured surface with superhydrophobic properties for removing oil from water.

    Science.gov (United States)

    Huang, Shouying

    2014-10-08

    In the present study, a superhydrophobic polyurethane (PU) sponge with hierarchically structured surface, which exhibits excellent performance in absorbing oils/organic solvents, was fabricated for the first time through mussel-inspired one-step copolymerization approach. Specifically, dopamine (a small molecular bioadhesive) and n-dodecylthiol were copolymerized in an alkaline aqueous solution to generate polydopamine (PDA) nanoaggregates with n-dodecylthiol motifs on the surface of the PU sponge skeletons. Then, the superhydrophobic sponge that comprised a hierarchical structured surface similar to the chemical/topological structures of lotus leaf was fabricated. The topological structures, surface wettability, and mechanical property of the sponge were characterized by scanning electron microscopy, contact angle experiments, and compression test. Just as a result of the highly porous structure, superhydrophobic property and strong mechanical stability, this sponge exhibited desirable absorption capability of oils/organic solvents (weight gains ranging from 2494% to 8670%), suggesting a promising sorbents for the removal of oily pollutants from water. Furthermore, thanks to the nonutilization of the complicated processes or sophisticated equipment, the fabrication of the superhydrophobic sponge seemed to be quite easy to scale up. All these merits make the sponge a competitive candidate when compared to the conventional absorbents, for example, nonwoven polypropylene fabric.

  20. Rigorous Approach in Investigation of Seismic Structure and Source Characteristicsin Northeast Asia: Hierarchical and Trans-dimensional Bayesian Inversion

    Science.gov (United States)

    Mustac, M.; Kim, S.; Tkalcic, H.; Rhie, J.; Chen, Y.; Ford, S. R.; Sebastian, N.

    2015-12-01

    Conventional approaches to inverse problems suffer from non-linearity and non-uniqueness in estimations of seismic structures and source properties. Estimated results and associated uncertainties are often biased by applied regularizations and additional constraints, which are commonly introduced to solve such problems. Bayesian methods, however, provide statistically meaningful estimations of models and their uncertainties constrained by data information. In addition, hierarchical and trans-dimensional (trans-D) techniques are inherently implemented in the Bayesian framework to account for involved error statistics and model parameterizations, and, in turn, allow more rigorous estimations of the same. Here, we apply Bayesian methods throughout the entire inference process to estimate seismic structures and source properties in Northeast Asia including east China, the Korean peninsula, and the Japanese islands. Ambient noise analysis is first performed to obtain a base three-dimensional (3-D) heterogeneity model using continuous broadband waveforms from more than 300 stations. As for the tomography of surface wave group and phase velocities in the 5-70 s band, we adopt a hierarchical and trans-D Bayesian inversion method using Voronoi partition. The 3-D heterogeneity model is further improved by joint inversions of teleseismic receiver functions and dispersion data using a newly developed high-efficiency Bayesian technique. The obtained model is subsequently used to prepare 3-D structural Green's functions for the source characterization. A hierarchical Bayesian method for point source inversion using regional complete waveform data is applied to selected events from the region. The seismic structure and source characteristics with rigorously estimated uncertainties from the novel Bayesian methods provide enhanced monitoring and discrimination of seismic events in northeast Asia.

  1. Hierarchical structures in Northern Hemispheric extratropical winter ocean-atmosphere interactions

    CERN Document Server

    Wiedermann, Marc; Handorf, Dörthe; Kurths, Jürgen; Donner, Reik V

    2015-01-01

    In recent years extensive studies on the Earth's climate system have been carried out by means of advanced complex network statistics. The great majority of these studies, however, have been focusing on investigating interaction structures within single climatological fields directly on or parallel to the Earth's surface. In this work, we develop a novel approach of node weighted interacting network measures to study ocean-atmosphere coupling in the Northern Hemisphere and construct 18 coupled climate networks, each consisting of two subnetworks. In all cases, one subnetwork represents monthly sea-surface temperature (SST) anomalies while the other is based on the monthly geopotential height (HGT) of isobaric surfaces at different pressure levels covering the troposphere as well as the lower stratosphere. The weighted cross-degree density proves to be consistent with the leading coupled pattern obtained from maximum covariance analysis, while network measures of higher order allow for a further analysis of th...

  2. Self-assembled biomimetic superhydrophobic hierarchical arrays.

    Science.gov (United States)

    Yang, Hongta; Dou, Xuan; Fang, Yin; Jiang, Peng

    2013-09-01

    Here, we report a simple and inexpensive bottom-up technology for fabricating superhydrophobic coatings with hierarchical micro-/nano-structures, which are inspired by the binary periodic structure found on the superhydrophobic compound eyes of some insects (e.g., mosquitoes and moths). Binary colloidal arrays consisting of exemplary large (4 and 30 μm) and small (300 nm) silica spheres are first assembled by a scalable Langmuir-Blodgett (LB) technology in a layer-by-layer manner. After surface modification with fluorosilanes, the self-assembled hierarchical particle arrays become superhydrophobic with an apparent water contact angle (CA) larger than 150°. The throughput of the resulting superhydrophobic coatings with hierarchical structures can be significantly improved by templating the binary periodic structures of the LB-assembled colloidal arrays into UV-curable fluoropolymers by a soft lithography approach. Superhydrophobic perfluoroether acrylate hierarchical arrays with large CAs and small CA hysteresis can be faithfully replicated onto various substrates. Both experiments and theoretical calculations based on the Cassie's dewetting model demonstrate the importance of the hierarchical structure in achieving the final superhydrophobic surface states. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Applied Bayesian Hierarchical Methods

    CERN Document Server

    Congdon, Peter D

    2010-01-01

    Bayesian methods facilitate the analysis of complex models and data structures. Emphasizing data applications, alternative modeling specifications, and computer implementation, this book provides a practical overview of methods for Bayesian analysis of hierarchical models.

  4. Programming with Hierarchical Maps

    DEFF Research Database (Denmark)

    Ørbæk, Peter

    This report desribes the hierarchical maps used as a central data structure in the Corundum framework. We describe its most prominent features, ague for its usefulness and briefly describe some of the software prototypes implemented using the technology....

  5. Identifying Overlapping and Hierarchical Thematic Structures in Networks of Scholarly Papers: A Comparison of Three Approaches

    CERN Document Server

    Havemann, Frank; Heinz, Michael; Struck, Alexander

    2011-01-01

    We implemented three recently proposed approaches to the identification of overlapping and hierarchical substructures in graphs and applied the corresponding algorithms to a network of 492 information-science papers coupled via their cited sources. The thematic substructures obtained and overlaps produced by the three hierarchical cluster algorithms were compared to a content-based categorisation, which we based on the interpretation of titles and keywords. We defined sets of papers dealing with three topics located on different levels of aggregation: h-index, webometrics, and bibliometrics. We identified these topics with branches in the dendrograms produced by the three cluster algorithms and compared the overlapping topics they detected with one another and with the three pre-defined paper sets. We discuss the advantages and drawbacks of applying the three approaches to paper networks in research fields.

  6. Assessing motivation for work environment improvements: internal consistency, reliability and factorial structure.

    Science.gov (United States)

    Hedlund, Ann; Ateg, Mattias; Andersson, Ing-Marie; Rosén, Gunnar

    2010-04-01

    Workers' motivation to actively take part in improvements to the work environment is assumed to be important for the efficiency of investments for that purpose. That gives rise to the need for a tool to measure this motivation. A questionnaire to measure motivation for improvements to the work environment has been designed. Internal consistency and test-retest reliability of the domains of the questionnaire have been measured, and the factorial structure has been explored, from the answers of 113 employees. The internal consistency is high (0.94), as well as the correlation for the total score (0.84). Three factors are identified accounting for 61.6% of the total variance. The questionnaire can be a useful tool in improving intervention methods. The expectation is that the tool can be useful, particularly with the aim of improving efficiency of companies' investments for work environment improvements. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. Globular structures of a helix-coil copolymer: Self-consistent treatment

    Science.gov (United States)

    Nowak, C.; Rostiashvili, V. G.; Vilgis, T. A.

    2007-01-01

    A self-consistent-field theory was developed in the grand canonical ensemble formulation to study transitions in a helix-coil multiblock globule. Helical and coil parts are treated as stiff rods and self-avoiding walks of variable lengths correspondingly. The resulting field theory takes, in addition to the conventional Zimm-Bragg, [J. Chem. Phys. 31, 526 (1959)] parameters, also three-dimensional interaction terms into account. The appropriate differential equations which determine the self-consistent fields were solved numerically with finite element method. Three different phase states are found: open chain, amorphous globule, and nematic liquid-crystalline (LC) globule. The LC-globule formation is driven by the interplay between the hydrophobic helical segment attraction and the anisotropic globule surface energy of an entropic nature. The full phase diagram of the helix-coil copolymer was calculated and thoroughly discussed. The suggested theory shows a clear interplay between secondary and tertiary structures in globular homopolypeptides.

  8. Facet Theory and the Mapping Sentence as Hermeneutically Consistent Structured Meta-Ontology and Structured Meta-Mereology

    Directory of Open Access Journals (Sweden)

    Paul M W Hackett

    2016-03-01

    Full Text Available When behaviour is interpreted in a reliable manner (i.e., robustly across different situations and times its explained meaning may be seen to possess hermeneutic consistency. In this essay I present an evaluation of the hermeneutic consistency that I propose may be present when the research tool know as the mapping sentence is used to create generic structural ontologies. I also claim that theoretical and empirical validity is a likely result of employing the mapping sentence in research design and interpretation. These claims are non-contentious within the realm of quantitative psychological and behavioural research. However, I extend the scope of both facet theory based research and claims for its structural utility, reliability and validity to philosophical and qualitative investigations. I assert that the hermeneutic consistency of a structural ontology is a product of a structural representation’s ontological components and the mereological relationships between these ontological sub-units: the mapping sentence seminally allows for the depiction of such structure.

  9. Hierarchical ZSM-11 with intergrowth structures:Synthesis,characterization and catalytic properties

    Institute of Scientific and Technical Information of China (English)

    Qingjun; Yu; Chaoyue; Cui; Qiang; Zhang; Jing; Chen; Yang; Li; Jinpeng; Sun; Chunyi; Li; Qiukai; Cui; Chaohe; Yang; Honghong; Shan

    2013-01-01

    Hierarchical ZSM-11 microspheres with intercrystalline mesoporous properties and rod-like crystals intergrowth morphology have been synthesized using a spot of tetrabutylammonium as a single template.XRD,FTIR,SEM,TEM and N2 adsorption analysis revealed that each individual particle was composed of nanosized rod crystals inserting each other and the intercrystalline voids existing among rods gave a significant mesopore size distribution.Steam treatment result demonstrated the excellent hydrothermal stability of samples.Various crystallization modes including constant temperature crystallization (one-stage crystallization) and two-stage temperature-varying crystallization with different 1st stage durations were investigated.The results suggested that the crystallization modes were mainly responsible for the adjustable particle size and textural properties of samples while the small amount of tetrabutylammonium bromide was mainly used to direct the formation of both ZSM-11 framework and its intergrowth morphology.Furthermore,the performance of optimal ZSM-11 as an active component for the catalytic pyrolysis of heavy oil was also investigated.Compared with the commercial pyrolysis catalyst,the hierarchical ZSM-11 catalyst exhibited a high selectivity to desired products(LPG+gasoline+diesel),as well as a much lower dry gas and coke yield,plus a high selectivity and yield of light olefins(C=3 C=4)and very poor selectivity to benzene.Therefore,fully open micropore-mesopore connectivity would make such hierarchically porous ZSM-11 zeolites very attractive for applications in clean petrochemical catalysis field.

  10. Beyond Poisson-Boltzmann: fluctuations and fluid structure in a self-consistent theory.

    Science.gov (United States)

    Buyukdagli, S; Blossey, R

    2016-09-01

    Poisson-Boltzmann (PB) theory is the classic approach to soft matter electrostatics and has been applied to numerous physical chemistry and biophysics problems. Its essential limitations are in its neglect of correlation effects and fluid structure. Recently, several theoretical insights have allowed the formulation of approaches that go beyond PB theory in a systematic way. In this topical review, we provide an update on the developments achieved in the self-consistent formulations of correlation-corrected Poisson-Boltzmann theory. We introduce a corresponding system of coupled non-linear equations for both continuum electrostatics with a uniform dielectric constant, and a structured solvent-a dipolar Coulomb fluid-including non-local effects. While the approach is only approximate and also limited to corrections in the so-called weak fluctuation regime, it allows us to include physically relevant effects, as we show for a range of applications of these equations.

  11. Beyond Poisson-Boltzmann: fluctuations and fluid structure in a self-consistent theory

    Science.gov (United States)

    Buyukdagli, S.; Blossey, R.

    2016-09-01

    Poisson-Boltzmann (PB) theory is the classic approach to soft matter electrostatics and has been applied to numerous physical chemistry and biophysics problems. Its essential limitations are in its neglect of correlation effects and fluid structure. Recently, several theoretical insights have allowed the formulation of approaches that go beyond PB theory in a systematic way. In this topical review, we provide an update on the developments achieved in the self-consistent formulations of correlation-corrected Poisson-Boltzmann theory. We introduce a corresponding system of coupled non-linear equations for both continuum electrostatics with a uniform dielectric constant, and a structured solvent—a dipolar Coulomb fluid—including non-local effects. While the approach is only approximate and also limited to corrections in the so-called weak fluctuation regime, it allows us to include physically relevant effects, as we show for a range of applications of these equations.

  12. Consistency relations for large scale structures with primordial non-Gaussianities

    CERN Document Server

    Valageas, Patrick; Nishimichi, Takahiro

    2016-01-01

    We investigate how the consistency relations of large-scale structures are modified when the initial density field is not Gaussian. We consider both scenarios where the primordial density field can be written as a nonlinear functional of a Gaussian field and more general scenarios where the probability distribution of the primordial density field can be expanded around the Gaussian distribution, up to all orders over $\\delta_{L0}$. Working at linear order over the non-Gaussianity parameters $f_{\\rm NL}^{(n)}$ or $S_n$, we find that the consistency relations for the matter density fields are modified as they include additional contributions that involve all-order mixed linear-nonlinear correlations $\\langle \\prod \\delta_L \\prod \\delta \\rangle$. We derive the conditions needed to recover the simple Gaussian form of the consistency relations. This corresponds to scenarios that become Gaussian in the squeezed limit. Our results also apply to biased tracers, and velocity or momentum cross-correlations.

  13. Holey graphene/polypyrrole nanoparticle hybrid aerogels with three-dimensional hierarchical porous structure for high performance supercapacitor

    Science.gov (United States)

    He, Yibo; Bai, Yonglong; Yang, Xiaofan; Zhang, Jinyang; Kang, Liping; Xu, Hua; Shi, Feng; Lei, Zhibin; Liu, Zong-Huai

    2016-06-01

    Holey graphene/polypyrrole hybrid aerogels (HGPAs) with three-dimensional (3D) hierarchical structure have been fabricated by freeze-drying holey graphene/polypyrrole hydrogels, which are assembled by using holey graphene (HG) nanosheets and polypyrrole (PPy) nanoparticles as assembling primitives. The as-prepared HGPAs materials show an interconnected and stable 3D porous network, and PPy nanoparticles uniformly embedded in the aerogel prevent the restacking of holey graphene (HG) nanosheets. The unique hierarchical porous structure and synergistic effect between PPy nanoparticles and HG nanosheets make HGPA hybrid aerogel electrode with a mass ratio of PPy/HGO = 0.75 exhibits high specific capacitance (418 F g-1) at a current density of 0.5 A g-1, extremely outstanding rate capability (80%) at various current densities from 0.5 to 20 A g-1 and good cycling performance (74%) after 2000 cycles in 1.0 M KOH aqueous electrolyte. Moreover, the effect of the PPy nanoparticle sizes in HGPAs on their electrochemical properties is also investigated, and PPy nanoparticles with relatively larger sizes are favorable of the good capacitive performance for the obtained electrodes. The facile and efficient preparation method for HGPAs electrodes may be developed for preparing other holey graphene-based hybrid aerogels with structure-controllable nanostructures.

  14. Hierarchical porous structured zeolite composite for removal of ionic contaminants from waste streams and effective encapsulation of hazardous waste.

    Science.gov (United States)

    Al-Jubouri, Sama M; Curry, Nicholas A; Holmes, Stuart M

    2016-12-15

    A hierarchical structured composite made from clinoptilolite supported on date stones carbon is synthesized using two techniques. The composites are manufactured by fixing a natural zeolite (clinoptilolite) to the porous surface of date stones carbon or by direct hydrothermal synthesis on to the surface to provide a supported high surface area ion-exchange material for metal ion removal from aqueous streams. The fixing of the clinoptilolite is achieved using sucrose and citric acid as a binder. The composites and pure clinoptilolite were compared to test the efficacy for the removal of Sr(2+) ions from an aqueous phase. The encapsulation of the Sr(2+) using either vitrification or a geo-polymer addition was tested to ensure that the hazardous waste can be made safe for disposal. The hierarchical structured composites were shown to achieve a higher ion exchange capacity per gram of zeolite than the pure clinoptilolite (65mg/g for the pure natural clinoptilolite and 72mg/g for the pure synthesized clinoptilolite) with the synthesized composite (160mg/g) having higher capacity than the natural clinoptilolite composite (95mg/g). The rate at which the equilibria were established followed the same trend showing the composite structure facilitates diffusion to the ion-exchange sites in the zeolite.

  15. Hierarchical linear modeling (HLM) of longitudinal brain structural and cognitive changes in alcohol-dependent individuals during sobriety.

    Science.gov (United States)

    Yeh, Ping-Hong; Gazdzinski, Stefan; Durazzo, Timothy C; Sjöstrand, Karl; Meyerhoff, Dieter J

    2007-12-01

    Hierarchical linear modeling (HLM) can reveal complex relationships between longitudinal outcome measures and their covariates under proper consideration of potentially unequal error variances. We demonstrate the application of HLM to the study of magnetic resonance imaging (MRI)-derived brain volume changes and cognitive changes in abstinent alcohol-dependent individuals as a function of smoking status, smoking severity, and drinking quantities. Twenty non-smoking recovering alcoholics (nsALC) and 30 age-matched smoking recovering alcoholics (sALC) underwent quantitative MRI and cognitive assessments at 1 week, 1 month, and 7 months of sobriety. Eight non-smoking light drinking controls were studied at baseline and 7 months later. Brain and ventricle volumes at each time point were quantified using MRI masks, while the boundary shift integral method measured volume changes between time points. Using HLM, we modeled volumetric and cognitive outcome measures as a function of cigarette and alcohol use variables. Different hierarchical linear models with unique model structures are presented and discussed. The results show that smaller brain volumes at baseline predict faster brain volume gains, which were also related to greater smoking and drinking severities. Over 7 months of abstinence from alcohol, sALC compared to nsALC showed less improvements in visuospatial learning and memory despite larger brain volume gains and ventricular shrinkage. Different and unique hierarchical linear models allow assessments of the complex relationships among outcome measures of longitudinal data sets. These HLM applications suggest that chronic cigarette smoking modulates the temporal dynamics of brain structural and cognitive changes in alcoholics during prolonged sobriety.

  16. The Origin of Hierarchical Structure in Self-Assembled Graphene Oxide Papers and the Effect on Mechanical Properties

    Science.gov (United States)

    Nandy, Krishanu

    The quest for new materials with ever improving properties has motivated interest in bulk nanostructured materials. Graphene, a two-dimensional sheet of hexagonally arranged carbon atoms, has been of particular interest given its exceptional mechanical, thermal, optical and electrical properties. Graphene oxide is a chemically modified form of graphene in which the honeycomb lattice of carbon atoms is decorated with oxygen bearing functional groups. Graphene oxide represents a facile route for the production of large quantities of graphene based materials, is stable in aqueous and polar organic solvents and has the potential for further chemical modification. In this dissertation, the origin and influence of hierarchical structure on the mechanical properties of graphene oxide paper and graphene oxide paper based materials has been investigated. Free-standing papers derived from graphene oxide are of interest as structural materials due to their impressive mechanical properties. While studies have investigated the mechanical properties of graphene oxide papers, little is known about the formation mechanism. Using a series of flash-freezing experiments on graphene oxide papers undergoing formation, a stop-motion animation of the fabrication process was obtained. The results explain the origin of the hierarchical nature of graphene oxide papers and provide a method for the tailoring of graphene oxide based materials. An in depth study of fusion of graphene oxide papers demonstrates a simple single-step route for the fabrication of practical materials derived from graphene oxide papers. Fused papers retain the properties of constituent papers allowing for the fabrication of mechanical heterostructures that replicate the hierarchical nature of natural materials. The contribution of the hierarchical nature of graphene oxide papers to the mechanical properties was examined by comparing papers formed by two different mechanisms. The intermediate length scale structures

  17. CHIMERA: Top-down model for hierarchical, overlapping and directed cluster structures in directed and weighted complex networks

    Science.gov (United States)

    Franke, R.

    2016-11-01

    In many networks discovered in biology, medicine, neuroscience and other disciplines special properties like a certain degree distribution and hierarchical cluster structure (also called communities) can be observed as general organizing principles. Detecting the cluster structure of an unknown network promises to identify functional subdivisions, hierarchy and interactions on a mesoscale. It is not trivial choosing an appropriate detection algorithm because there are multiple network, cluster and algorithmic properties to be considered. Edges can be weighted and/or directed, clusters overlap or build a hierarchy in several ways. Algorithms differ not only in runtime, memory requirements but also in allowed network and cluster properties. They are based on a specific definition of what a cluster is, too. On the one hand, a comprehensive network creation model is needed to build a large variety of benchmark networks with different reasonable structures to compare algorithms. On the other hand, if a cluster structure is already known, it is desirable to separate effects of this structure from other network properties. This can be done with null model networks that mimic an observed cluster structure to improve statistics on other network features. A third important application is the general study of properties in networks with different cluster structures, possibly evolving over time. Currently there are good benchmark and creation models available. But what is left is a precise sandbox model to build hierarchical, overlapping and directed clusters for undirected or directed, binary or weighted complex random networks on basis of a sophisticated blueprint. This gap shall be closed by the model CHIMERA (Cluster Hierarchy Interconnection Model for Evaluation, Research and Analysis) which will be introduced and described here for the first time.

  18. Assessing the Graphical and Algorithmic Structure of Hierarchical Coloured Petri Net Models

    Directory of Open Access Journals (Sweden)

    George Benwell

    1994-11-01

    Full Text Available Petri nets, as a modelling formalism, are utilised for the analysis of processes, whether for explicit understanding, database design or business process re-engineering. The formalism, however, can be represented on a virtual continuum from highly graphical to largely algorithmic. The use and understanding of the formalism will, in part, therefore depend on the resultant complexity and power of the representation and, on the graphical or algorithmic preference of the user. This paper develops a metric which will indicate the graphical or algorithmic tendency of hierarchical coloured Petri nets.

  19. Iterative Maps with Hierarchical Clustering for the Observed Scales of Astrophysical and Cosmological Structures

    CERN Document Server

    Capozziello, S; De Siena, S; Guerra, F; Illuminati, F

    2000-01-01

    We derive, in order of magnitude, the observed astrophysical and cosmologicalscales in the Universe, from neutron stars to superclusters of galaxies, up to,asymptotically, the observed radius of the Universe. This result is obtained byintroducing a recursive scheme of alternating hierachical mechanisms ofthree-dimensional and two-dimensional close packings of gravitationallyinteracting objects. The iterative scheme yields a rapidly converging geometricsequence, which can be described as a hierarchical clustering of aggregates,having the observed radius of the Universe as its fixed point.

  20. Universal hierarchical behavior of citation networks

    CERN Document Server

    Mones, Enys; Vicsek, Tamás

    2014-01-01

    Many of the essential features of the evolution of scientific research are imprinted in the structure of citation networks. Connections in these networks imply information about the transfer of knowledge among papers, or in other words, edges describe the impact of papers on other publications. This inherent meaning of the edges infers that citation networks can exhibit hierarchical features, that is typical of networks based on decision-making. In this paper, we investigate the hierarchical structure of citation networks consisting of papers in the same field. We find that the majority of the networks follow a universal trend towards a highly hierarchical state, and i) the various fields display differences only concerning their phase in life (distance from the "birth" of a field) or ii) the characteristic time according to which they are approaching the stationary state. We also show by a simple argument that the alterations in the behavior are related to and can be understood by the degree of specializatio...

  1. Hierarchically structured superhydrophobic flowers with low hysteresis of the wild pansy (Viola tricolor – new design principles for biomimetic materials

    Directory of Open Access Journals (Sweden)

    Anna J. Schulte

    2011-05-01

    Full Text Available Hierarchically structured flower leaves (petals of many plants are superhydrophobic, but water droplets do not roll-off when the surfaces are tilted. On such surfaces water droplets are in the “Cassie impregnating wetting state”, which is also known as the “petal effect”. By analyzing the petal surfaces of different species, we discovered interesting new wetting characteristics of the surface of the flower of the wild pansy (Viola tricolor. This surface is superhydrophobic with a static contact angle of 169° and very low hysteresis, i.e., the petal effect does not exist and water droplets roll-off as from a lotus (Nelumbo nucifera leaf. However, the surface of the wild pansy petal does not possess the wax crystals of the lotus leaf. Its petals exhibit high cone-shaped cells (average size 40 µm with a high aspect ratio (2.1 and a very fine cuticular folding (width 260 nm on top. The applied water droplets are in the Cassie–Baxter wetting state and roll-off at inclination angles below 5°. Fabricated hydrophobic polymer replicas of the wild pansy were prepared in an easy two-step moulding process and possess the same wetting characteristics as the original flowers. In this work we present a technical surface with a new superhydrophobic, low adhesive surface design, which combines the hierarchical structuring of petals with a wetting behavior similar to that of the lotus leaf.

  2. Hierarchically structured suspended TiO2 nanofibers for use in UV and pH sensor devices.

    Science.gov (United States)

    Lee, Won Seok; Park, Yang-Seok; Cho, Yoon-Kyoung

    2014-08-13

    Photoelectrochemical sensors based on hierarchically structured titanium dioxide (TiO2) nanofibers (NFs) were fabricated by combination of electrospinning, carbon microelectromechanical systems (MEMS), and hydrothermal reaction. During the electrospinning step, a rotating drum collector was used to align and position NFs of titanium tetraisopropoxide (TTIP) in polyvinylpyrrolidone (PVP) on top of a carbon-MEMS structure. Following calcination under vacuum, a stable ohmic contact was obtained between suspended TiO2-carbon NFs (TiO2/C NF) and the carbon electrodes. Subsequent to this, a hierarchical nanostructure of TiO2 nanowires (TiO2 NWs) was hydrothermally synthesized onto the TiO2/C NFs and successfully utilized as UV and pH sensors. This is the first demonstration of a semiconductor-based nanofiber sensor suspended on carbon electrodes that has been achieved by a relatively simple and cost-effective electrospinning method. Furthermore, these sensors demonstrate a high sensitivity, as well as a stable ohmic contact, due to the large surface area of the TiO2 NWs and the carbon-carbon contact between the suspended TiO2/C NFs and carbon electrodes.

  3. Determination of genetic structure of germplasm collections: are traditional hierarchical clustering methods appropriate for molecular marker data?

    NARCIS (Netherlands)

    Odong, T.L.; Heerwaarden, van J.; Jansen, J.; Hintum, van T.J.L.; Eeuwijk, van F.A.

    2011-01-01

    Despite the availability of newer approaches, traditional hierarchical clustering remains very popular in genetic diversity studies in plants. However, little is known about its suitability for molecular marker data. We studied the performance of traditional hierarchical clustering techniques using

  4. Consistent Data Assimilation of Structural Isotopes: 23Na and 56Fe

    Energy Technology Data Exchange (ETDEWEB)

    Giuseppe Palmiotti

    2010-09-01

    A new approach is proposed, the consistent data assimilation, that allows to link the integral data experiment results to basic nuclear parameters employed by evaluators to generate ENDF/B point energy files in order to improve them. Practical examples are provided for the structural materials 23Na and 56Fe. The sodium neutron propagation experiments, EURACOS and JANUS-8, are used to improve via modifications of 23Na nuclear parameters (like scattering radius, resonance parameters, Optical model parameters, Statistical Hauser-Feshbach model parameters, and Preequilibrium Exciton model parameters) the agreement of calculation versus experiments for a series of measured reaction rate detectors slopes. For the 56Fe case the EURACOS and ZPR3 assembly 54 are used. Results have shown inconsistencies in the set of nuclear parameters used so that further investigation is needed. Future work involves comparison of results against a more traditional multigroup adjustments, and extension to other isotope of interest in the reactor community.

  5. Consistent truncations of M-theory for general SU(2) structures

    CERN Document Server

    Triendl, Hagen

    2015-01-01

    In seven dimensions any spin manifold admits an SU(2) structure and therefore very general M-theory compactifications have the potential to allow for a reduction to N=4 gauged supergravity. We perform this general SU(2) reduction and give the relation of SU(2) torsion classes and fluxes to gaugings in the N=4 theory. We furthermore show explicitly that this reduction is a consistent truncation of the eleven-dimensional theory, in other words classical solutions of the reduced theory also solve the eleven-dimensional equations of motion. This reduction generalizes previous M-theory reductions on Tri-Sasakian manifolds and type IIA reductions on Calabi-Yau manifolds of vanishing Euler number. Moreover, it can also be applied to compactifications on certain G2 holonomy manifolds and to more general flux backgrounds.

  6. Ion acoustic solitary structures in a collisionless unmagnetized plasma consisting of nonthermal electrons and isothermal positrons

    CERN Document Server

    Paul, Ashesh

    2016-01-01

    Employing the Sagdeev pseudo-potential technique the ion acoustic solitary structures have been investigated in an unmagnetized collisionless plasma consisting of adiabatic warm ions, nonthermal electrons and isothermal positrons. The qualitatively different compositional parameter spaces clearly indicate the existence domains of solitons and double layers with respect to any parameter of the present plasma system. The present system supports the negative potential double layer which always restricts the occurrence of negative potential solitons. The system also supports positive potential double layers when the ratio of the average thermal velocity of positrons to that of electrons is less than a critical value. However, there exists a parameter regime for which the positive potential double layer is unable to restrict the occurrence of positive potential solitary waves and in this region of the parameter space, there exist positive potential solitary waves after the formation of a positive potential double ...

  7. Hierarchically structured self-supported latex films for flexible and semi-transparent electronics

    Science.gov (United States)

    Määttänen, Anni; Ihalainen, Petri; Törngren, Björn; Rosqvist, Emil; Pesonen, Markus; Peltonen, Jouko

    2016-02-01

    Different length scale alterations in topography, surface texture, and symmetry are known to evoke diverse cell behavior, including adhesion, orientation, motility, cytoskeletal condensation, and modulation of intracellular signaling pathways. In this work, self-supported latex films with well-defined isotropic/anisotropic surface features and hierarchical morphologies were fabricated by a peel-off process from different template surfaces. In addition, the latex films were used as substrates for evaporated ultrathin gold films with nominal thicknesses of 10 and 20 nm. Optical properties and topography of the samples were characterized using UV-vis spectroscopy and Atomic Force Microscopy (AFM) measurements, respectively. The latex films showed high-level transmittance of visible light, enabling the fabrication of semi-transparent gold electrodes. Electrochemical impedance spectroscopy (EIS) measurements were carried out for a number of days to investigate the long-term stability of the electrodes. The effect of 1-octadecanethiol (ODT) and HS(CH2)11OH (MuOH) thiolation and protein (human serum albumin, HSA) adsorption on the impedance and capacitance was studied. In addition, cyclic voltammetry (CV) measurements were carried out to determine active medicinal components, i.e., caffeic acid with interesting biological activities and poorly water-soluble anti-inflammatory drug, piroxicam. The results show that the fabrication procedure presented in this study enables the formation of platforms with hierarchical morphologies for multimodal (optical and electrical) real-time monitoring of length-scale-dependent biomaterial-surface interactions.

  8. Amazon Forests Maintain Consistent Canopy Structure and Greenness During the Dry Season

    Science.gov (United States)

    Morton, Douglas C.; Nagol, Jyoteshwar; Carabajal, Claudia C.; Rosette, Jacqueline; Palace, Michael; Cook, Bruce D.; Vermote, Eric F.; Harding, David J.; North, Peter R. J.

    2014-01-01

    The seasonality of sunlight and rainfall regulates net primary production in tropical forests. Previous studies have suggested that light is more limiting than water for tropical forest productivity, consistent with greening of Amazon forests during the dry season in satellite data.We evaluated four potential mechanisms for the seasonal green-up phenomenon, including increases in leaf area or leaf reflectance, using a sophisticated radiative transfer model and independent satellite observations from lidar and optical sensors. Here we show that the apparent green up of Amazon forests in optical remote sensing data resulted from seasonal changes in near-infrared reflectance, an artefact of variations in sun-sensor geometry. Correcting this bidirectional reflectance effect eliminated seasonal changes in surface reflectance, consistent with independent lidar observations and model simulations with unchanging canopy properties. The stability of Amazon forest structure and reflectance over seasonal timescales challenges the paradigm of light-limited net primary production in Amazon forests and enhanced forest growth during drought conditions. Correcting optical remote sensing data for artefacts of sun-sensor geometry is essential to isolate the response of global vegetation to seasonal and interannual climate variability.

  9. Retinal anatomy of the New Zealand kiwi: structural traits consistent with their nocturnal behavior.

    Science.gov (United States)

    Corfield, Jeremy R; Parsons, Stuart; Harimoto, Yoshitetsu; Acosta, Monica L

    2015-04-01

    Kiwi (Apteryx spp.) have a visual system unlike that of other nocturnal birds, and have specializations to their auditory, olfactory, and tactile systems. Eye size, binocular visual fields and visual brain centers in kiwi are proportionally the smallest yet recorded among birds. Given the many unique features of the kiwi visual system, we examined the laminar organization of the kiwi retina to determine if they evolved increased light sensitivity with a shift to a nocturnal niche or if they retained features of their diurnal ancestor. The laminar organization of the kiwi retina was consistent with an ability to detect low light levels similar to that of other nocturnal species. In particular, the retina appeared to have a high proportion of rod photoreceptors as compared to diurnal species, as evidenced by a thick outer nuclear layer, and also numerous thin photoreceptor segments intercalated among the conical shaped cone photoreceptor inner segments. Therefore, the retinal structure of kiwi was consistent with increased light sensitivity, although other features of the visual system, such as eye size, suggest a reduced reliance on vision. The unique combination of a nocturnal retina and smaller than expected eye size, binocular visual fields, and brain regions make the kiwi visual system unlike that of any bird examined to date. Whether these features of their visual system are an evolutionary design that meets their specific visual needs or are a remnant of a kiwi ancestor that relied more heavily on vision is yet to be determined.

  10. Consistent structures and interactions by density functional theory with small atomic orbital basis sets

    Science.gov (United States)

    Grimme, Stefan; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas

    2015-08-01

    A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of "low-cost" electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT methods

  11. Consistent structures and interactions by density functional theory with small atomic orbital basis sets.

    Science.gov (United States)

    Grimme, Stefan; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas

    2015-08-07

    A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of "low-cost" electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT methods

  12. Consistent structures and interactions by density functional theory with small atomic orbital basis sets

    Energy Technology Data Exchange (ETDEWEB)

    Grimme, Stefan, E-mail: grimme@thch.uni-bonn.de; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas [Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms Universität Bonn, Beringstraße 4, 53115 Bonn (Germany)

    2015-08-07

    A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of “low-cost” electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT

  13. Analyzing security protocols in hierarchical networks

    DEFF Research Database (Denmark)

    Zhang, Ye; Nielson, Hanne Riis

    2006-01-01

    Validating security protocols is a well-known hard problem even in a simple setting of a single global network. But a real network often consists of, besides the public-accessed part, several sub-networks and thereby forms a hierarchical structure. In this paper we first present a process calculus...... capturing the characteristics of hierarchical networks and describe the behavior of protocols on such networks. We then develop a static analysis to automate the validation. Finally we demonstrate how the technique can benefit the protocol development and the design of network systems by presenting a series...

  14. Nanocrystalline TiO{sub 2} photocatalytic membranes with a hierarchical mesoporous multilayer structure: synthesis, characterization, and multifunction

    Energy Technology Data Exchange (ETDEWEB)

    Choi, H.; Dionysiou, D.D. [Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221-0071 (United States); Sofranko, A.C. [Department of Chemical Engineering, University of Virginia, Charlottesville, VA 22904-4741 (United States)

    2006-05-19

    A novel sol-gel dip-coating process to fabricate nanocrystalline TiO{sub 2} photocatalytic membranes with a robust hierarchical mesoporous multilayer and improved performance has been studied. Various titania sols containing poly(oxyethylenesorbitan monooleate) (Tween 80) surfactant as a pore-directing agent to tailor-design the porous structure of TiO{sub 2} materials at different molar ratios of Tween 80/isopropyl alcohol/acetic acid/titanium tetraisopropoxide = R:45:6:1 have been synthesized. The sols are dip-coated on top of a homemade porous alumina substrate to fabricate TiO{sub 2}/Al{sub 2}O{sub 3} composite membranes, dried, and calcined, and this procedure is repeated with varying sols in succession. The resulting asymmetric mesoporous TiO{sub 2} membrane with a thickness of 0.9 {mu}m exhibits a hierarchical change in pore diameter from 2-6, through 3-8, to 5-11 nm from the top to the bottom layer. Moreover, the corresponding porosity is incremented from 46.2, through 56.7, to 69.3 %. Compared to a repeated-coating process using a single sol, the hierarchical multilayer process improves water permeability significantly without sacrificing the organic retention and photocatalytic activity of the TiO{sub 2} membranes. The prepared TiO{sub 2} photocatalytic membrane has great potential in developing highly efficient water treatment and reuse systems, for example, decomposition of organic pollutants, inactivation of pathogenic microorganisms, physical separation of contaminants, and self-antifouling action because of its multifunctional capability. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  15. Hierarchical spatial segregation of two Mediterranean vole species: the role of patch-network structure and matrix composition.

    Science.gov (United States)

    Pita, Ricardo; Lambin, Xavier; Mira, António; Beja, Pedro

    2016-09-01

    According to ecological theory, the coexistence of competitors in patchy environments may be facilitated by hierarchical spatial segregation along axes of environmental variation, but empirical evidence is limited. Cabrera and water voles show a metapopulation-like structure in Mediterranean farmland, where they are known to segregate along space, habitat, and time axes within habitat patches. Here, we assess whether segregation also occurs among and within landscapes, and how this is influenced by patch-network and matrix composition. We surveyed 75 landscapes, each covering 78 ha, where we mapped all habitat patches potentially suitable for Cabrera and water voles, and the area effectively occupied by each species (extent of occupancy). The relatively large water vole tended to be the sole occupant of landscapes with high habitat amount but relatively low patch density (i.e., with a few large patches), and with a predominantly agricultural matrix, whereas landscapes with high patch density (i.e., many small patches) and low agricultural cover, tended to be occupied exclusively by the small Cabrera vole. The two species tended to co-occur in landscapes with intermediate patch-network and matrix characteristics, though their extents of occurrence were negatively correlated after controlling for environmental effects. In combination with our previous studies on the Cabrera-water vole system, these findings illustrated empirically the occurrence of hierarchical spatial segregation, ranging from within-patches to among-landscapes. Overall, our study suggests that recognizing the hierarchical nature of spatial segregation patterns and their major environmental drivers should enhance our understanding of species coexistence in patchy environments.

  16. Hierarchical Factor Structure of the Turkish Version of the Posttraumatic Growth Inventory in a Normal Population

    Directory of Open Access Journals (Sweden)

    Mucahit Kagan

    2012-10-01

    Full Text Available Background: Negative consequences of traumatic experiences, such as depression, anxiety, or dissociative symptoms, etc. have been reported by many researchers. However, it is proposed that stressful events not only lead to poor psychological outcomes but also may trigger positive changes. Several instruments gauging posttraumatic benefits have been developed to examine the effects of factors that may promote positive psychological outcomes in the aftermath of stressful events. The Posttraumatic Growth Inventory (PTGI is one of the prominent instruments that assess posttraumatic positive changes. In this study we aimed to assess psychometric properties of the Turkish version of the PTGI. Method: This study differed to an extent from previous studies concerning the features of the PTGI. We used a dispositional form of the instrument in a sample recruited from high school and university students. Our data were collected from 723 volunteers. 367 subjects were males (50.76% and 356 subjects were females (49.24%. Also we did not specify any selection criteria in recruiting subjects owing to their adverse life experiences with a presumption that stressful life events are not uncommon in normal population. We administered to participants a dispositional form of the Posttraumatic Growth Inventory and the Personal View Survey-III. Item statistics for the measure were computed. We performed an explanatory factor analysis by using principal components with promax rotation and a confirmatory factor analysis by using structural equation modeling. Since the factor inter-correlations were higher than .40 we computed Schmid-Leiman transformation to obtain second-order general factor loadings. Inner consistencies and 15-day test-retest intracorrelations were calculated. Results: Item discrimination indexes ranged from .28 to .72. Promax rotated principal components analysis pointed out a three-factor structure. It was found in model testing with structural

  17. Structural investigation of the O-specific polysaccharides of Morganella morganii consisting of two higher sugars.

    Science.gov (United States)

    Kilcoyne, Michelle; Shashkov, Alexander S; Senchenkova, Sof'ya A; Knirel, Yuriy A; Vinogradov, Evgeny V; Radziejewska-Lebrecht, Joanna; Galimska-Stypa, Regina; Savage, Angela V

    2002-10-01

    The lipopolysaccharide of the bacterium Morganella morganii (strain KF 1676, RK 4222) yielded two polysaccharides, PS1 and PS2, when subjected to mild acid degradation followed by GPC. The polysaccharides were studied by 1H and 13C NMR spectroscopy, including two-dimensional COSY, TOCSY, NOESY, 1H,(13)C HMQC, and HMBC experiments. Each polysaccharide was found to contain a disaccharide repeating unit consisting of two higher sugars, 5-acetamidino-7-acetamido-3,5,7,9-tetradeoxy-L-glycero-D-galacto-non-2-ulosonic acid (a derivative of 8-epilegionaminic acid, 8eLeg5Am7Ac) and 2-acetamido-4-C-(3'-carboxamide-2',2'-dihydroxypropyl)-2,6-dideoxy-D-galactose (shewanellose, She). The two polysaccharides differ only in the ring size of shewanellose and have the following structures:Shewanellose has been previously identified in a phenol-soluble polysaccharide from Shewanella putrefaciens A6, which shows a close structural similarity to PS2.

  18. Thermocline Storage Filled with Structured Ceramics. Numerical Consistency of the Developed Numerical Model and First Observations

    Science.gov (United States)

    Motte, Fabrice; Bugler-Lamb, Samuel L.; Falcoz, Quentin

    2015-07-01

    The attraction of solar energy is greatly enhanced by the possibility of it being used during times of reduced or non-existent solar flux, such as weather induced intermittences or the darkness of the night. Therefore optimizing thermal storage for use in solar energy plants is crucial for the success of this sustainable energy source. Here we present a study of a structured bed filler dedicated to Thermocline type thermal storage, believed to outweigh the financial and thermal benefits of other systems currently in use such as packed bed Thermocline tanks. Several criterions such as Thermocline thickness and Thermocline centering are defined with the purpose of facilitating the assessment of the efficiency of the tank to complement the standard concepts of power output. A numerical model is developed that reduces to two dimensions the modeling of such a tank. The structure within the tank is designed to be built using simple bricks harboring rectangular channels through which the solar heat transfer and storage fluid will flow. The model is scrutinized and tested for physical robustness, and the results are presented in this paper. The consistency of the model is achieved within particular ranges for each physical variable.

  19. Recent Advances in Unconventional Lithography for Challenging 3D Hierarchical Structures and Their Applications

    Directory of Open Access Journals (Sweden)

    Jong Uk Kim

    2016-01-01

    Full Text Available In nanoscience and nanotechnology, nanofabrication is critical. Among the required processes for nanofabrication, lithography is one of core issues. Although conventional photolithography with recent remarkable improvement has contributed to the industry during the past few decades, fabrication of 3-dimensional (3D nanostructure is still challenging. In this review, we summarize recent advances for the construction of 3D nanostructures by unconventional lithography and the combination of two top-down approaches or top-down and bottom-up approaches. We believe that the 3D hierarchical nanostructures described here will have a broad range of applications having adaptable levels of functional integration of precisely controlled nanoarchitectures that are required by not only academia, but also industry.

  20. Hierarchical spatial genetic structure in a distinct population segment of greater sage-grouse

    Science.gov (United States)

    Oyler-McCance, Sara J.; Casazza, Michael L.; Fike, Jennifer A.; Coates, Peter S.

    2014-01-01

    Greater sage-grouse (Centrocercus urophasianus) within the Bi-State Management Zone (area along the border between Nevada and California) are geographically isolated on the southwestern edge of the species’ range. Previous research demonstrated that this population is genetically unique, with a high proportion of unique mitochondrial DNA (mtDNA) haplotypes and with significant differences in microsatellite allele frequencies compared to populations across the species’ range. As a result, this population was considered a distinct population segment (DPS) and was recently proposed for listing as threatened under the U.S. Endangered Species Act. A more comprehensive understanding of the boundaries of this genetically unique population (where the Bi-State population begins) and an examination of genetic structure within the Bi-State is needed to help guide effective management decisions. We collected DNA from eight sampling locales within the Bi-State (N = 181) and compared those samples to previously collected DNA from the two most proximal populations outside of the Bi-State DPS, generating mtDNA sequence data and amplifying 15 nuclear microsatellites. Both mtDNA and microsatellite analyses support the idea that the Bi-State DPS represents a genetically unique population, which has likely been separated for thousands of years. Seven mtDNA haplotypes were found exclusively in the Bi-State population and represented 73 % of individuals, while three haplotypes were shared with neighboring populations. In the microsatellite analyses both STRUCTURE and FCA separate the Bi-State from the neighboring populations. We also found genetic structure within the Bi-State as both types of data revealed differences between the northern and southern part of the Bi-State and there was evidence of isolation-by-distance. STRUCTURE revealed three subpopulations within the Bi-State consisting of the northern Pine Nut Mountains (PNa), mid Bi-State, and White Mountains (WM) following a

  1. Fabrication of hierarchical hybrid structures using bio-enabled layer-by-layer self-assembly.

    Science.gov (United States)

    Hnilova, Marketa; Karaca, Banu Taktak; Park, James; Jia, Carol; Wilson, Brandon R; Sarikaya, Mehmet; Tamerler, Candan

    2012-05-01

    Development of versatile and flexible assembly systems for fabrication of functional hybrid nanomaterials with well-defined hierarchical and spatial organization is of a significant importance in practical nanobiotechnology applications. Here we demonstrate a bio-enabled self-assembly technique for fabrication of multi-layered protein and nanometallic assemblies utilizing a modular gold-binding (AuBP1) fusion tag. To accomplish the bottom-up assembly we first genetically fused the AuBP1 peptide sequence to the C'-terminus of maltose-binding protein (MBP) using two different linkers to produce MBP-AuBP1 hetero-functional constructs. Using various spectroscopic techniques, surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR), we verified the exceptional binding and self-assembly characteristics of AuBP1 peptide. The AuBP1 peptide tag can direct the organization of recombinant MBP protein on various gold surfaces through an efficient control of the organic-inorganic interface at the molecular level. Furthermore using a combination of soft-lithography, self-assembly techniques and advanced AuBP1 peptide tag technology, we produced spatially and hierarchically controlled protein multi-layered assemblies on gold nanoparticle arrays with high molecular packing density and pattering efficiency in simple, reproducible steps. This model system offers layer-by-layer assembly capability based on specific AuBP1 peptide tag and constitutes novel biological routes for biofabrication of various protein arrays, plasmon-active nanometallic assemblies and devices with controlled organization, packing density and architecture.

  2. The role of the IFG and pSTS in syntactic prediction: Evidence from a parametric study of hierarchical structure in fMRI.

    Science.gov (United States)

    Matchin, William; Hammerly, Christopher; Lau, Ellen

    2017-03-01

    Sentences encode hierarchical structural relations among words. Several neuroimaging experiments aiming to localize combinatory operations responsible for creating this structure during sentence comprehension have contrasted short, simple phrases and sentences to unstructured controls. Some of these experiments have revealed activation in the left inferior frontal gyrus (IFG) and posterior superior temporal sulcus (pSTS), associating these regions with basic syntactic combination. However, the wide variability of these effects across studies raises questions about this interpretation. In an fMRI experiment, we provide support for an alternative hypothesis: these regions underlie top-down syntactic predictions that facilitate sentence processing but are not necessary for building syntactic structure. We presented stimuli with three levels of structure: unstructured lists, two-word phrases, and simple, short sentences; and two levels of content: natural stimuli with real words and stimuli with open-class items replaced with pseudowords (jabberwocky). While both the phrase and sentence conditions engaged syntactic combination, our experiment only encouraged syntactic prediction in the sentence condition. We found increased activity for both natural and jabberwocky sentences in the left IFG (pars triangularis and pars orbitalis) and pSTS relative to unstructured word lists and two-word phrases, but we did not find any such effects for two-word phrases relative to unstructured word lists in these areas. Our results are most consistent with the hypothesis that increased activity in IFG and pSTS for basic contrasts of structure reflects syntactic prediction. The pars opercularis of the IFG showed a response profile consistent with verbal working memory. We found incremental effects of structure in the anterior temporal lobe (ATL), and increased activation only for sentences in the angular gyrus (AG)/temporal-parietal junction (TPJ) - both regions showed these effects for

  3. Cosmology and astrophysics from relaxed galaxy clusters – V. Consistency with cold dark matter structure formation

    Energy Technology Data Exchange (ETDEWEB)

    Mantz, A.B.; /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Allen, S.W.; /KIPAC, Menlo Park /Stanford U., Phys. Dept. /SLAC; Morris, R.Glenn; /KIPAC, Menlo Park /SLAC

    2016-07-15

    This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the cold dark matter (CDM) paradigm. We present constraints on the concentration–mass relation for massive clusters, finding a power-law mass dependence with a slope of κm = -0.16 ± 0.07, in agreement with CDM predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κζ = -0.17 ± 0.26), with an intrinsic scatter of σln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ~50 kpc–1 Mpc), and test for departures from the simple Navarro–Frenk–White (NFW) form, for which the logarithmic slope of the density profile tends to -1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σβ = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σα = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.

  4. Cosmology and astrophysics from relaxed galaxy clusters - V. Consistency with cold dark matter structure formation

    Science.gov (United States)

    Mantz, A. B.; Allen, S. W.; Morris, R. G.

    2016-10-01

    This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the cold dark matter (CDM) paradigm. We present constraints on the concentration-mass relation for massive clusters, finding a power-law mass dependence with a slope of κm = -0.16 ± 0.07, in agreement with CDM predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κζ = -0.17 ± 0.26), with an intrinsic scatter of σln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ˜50 kpc-1 Mpc), and test for departures from the simple Navarro-Frenk-White (NFW) form, for which the logarithmic slope of the density profile tends to -1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σβ = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σα = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.

  5. Synthetic Architecture of MgO/C Nanocomposite from Hierarchical-Structured Coordination Polymer toward Enhanced CO2 Capture.

    Science.gov (United States)

    Li, Ping; Liu, Wen; Dennis, John S; Zeng, Hua Chun

    2017-03-22

    Highly efficient, durable, and earth-abundant solid sorbents are of paramount importance for practical carbon capture, storage, and utilization. Here, we report a novel and facile two-step strategy to synthesize a group of hierarchically structured porous MgO/C nanocomposites using flowerlike Mg-containing coordination polymer as a precursor. The new nanocomposites exhibit superb CO2 capture performance with sorption capacity up to 30.9 wt % (at 27 °C, 1 bar CO2), fast sorption kinetics, and long cycling life. Importantly, the achieved capacity is >14 times higher than that of commercial MgO, and favorably exceeds the highest value recorded to date for MgO-based sorbents under similar operating conditions. On the basis of the morphological and textural property analysis, together with CO2 sorption mechanism study using CO2-TPD and DRIFT techniques, the outstanding performance in CO2 uptake originates from unique features of this type of sorbent materials, which include hierarchical architecture, porous building blocks of nanosheets, high specific surface area (ca. 300 m(2)/g), evenly dispersed MgO nanocrystallites (ca. 3 nm) providing abundant active sites, and the in situ generated carbon matrix that acts as a stabilizer to prevent the growth and agglomeration of MgO crystallites. The nanocomposite system developed in this work shows good potential for future low-cost CO2 abatement and utilization.

  6. Hierarchical structure of genetic distances: Effects of matrix size, spatial distribution and correlation structure among gene frequencies

    Directory of Open Access Journals (Sweden)

    Flávia Melo Rodrigues

    1998-06-01

    Full Text Available Geographic structure of genetic distances among local populations within species, based on allozyme data, has usually been evaluated by estimating genetic distances clustered with hierarchical algorithms, such as the unweighted pair-group method by arithmetic averages (UPGMA. The distortion produced in the clustering process is estimated by the cophenetic correlation coefficient. This hierarchical approach, however, can fail to produce an accurate representation of genetic distances among populations in a low dimensional space, especially when continuous (clinal or reticulate patterns of variation exist. In the present study, we analyzed 50 genetic distance matrices from the literature, for animal taxa ranging from Platyhelminthes to Mammalia, in order to determine in which situations the UPGMA is useful to understand patterns of genetic variation among populations. The cophenetic correlation coefficients, derived from UPGMA based on three types of genetic distance coefficients, were correlated with other parameters of each matrix, including number of populations, loci, alleles, maximum geographic distance among populations, relative magnitude of the first eigenvalue of covariance matrix among alleles and logarithm of body size. Most cophenetic correlations were higher than 0.80, and the highest values appeared for Nei's and Rogers' genetic distances. The relationship between cophenetic correlation coefficients and the other parameters analyzed was defined by an "envelope space", forming triangles in which higher values of cophenetic correlations are found for higher values in the parameters, though low values do not necessarily correspond to high cophenetic correlations. We concluded that UPGMA is useful to describe genetic distances based on large distance matrices (both in terms of elevated number of populations or alleles, when dimensionality of the system is low (matrices with large first eigenvalues or when local populations are separated

  7. Fabrication of α-Fe2O3/TiO2 bi-functional composites with hierarchical and hollow structures and their application in water treatment

    Science.gov (United States)

    Li, Yinhui; Zhang, Na; Chen, Jianxin; Li, Ruijuan; Li, Liang; Li, Kunyu

    2016-02-01

    The α-Fe2O3/TiO2 bi-functional composites with hierarchical and hollow structures are fabricated through a hydrothermal route. The adsorption performance and photocatalytic activity of the composites towards Pb2+ are investigated in this work. Different adsorption kinetics models and equilibrium models are used to explore the adsorption behavior of hierarchical α-Fe2O3/TiO2 hollow spheres. Experimental data show that adsorption kinetics of the hierarchical α-Fe2O3/TiO2 hollow spheres can be fitted well by the pseudo-second-order model, while the isothermal data can be perfectly described by the Langmuir adsorption model. The maximum adsorption capacity of the hierarchical α-Fe2O3/TiO2 hollow spheres is 32.36 mg g-1. Moreover, the hierarchical α-Fe2O3/TiO2 hollow spheres possess photocatalytic oxidation character under simulated solar light irradiation. The results demonstrate that the hierarchical α-Fe2O3/TiO2 hollow spheres, as effective and cheap materials, can be applied to the removal of heavy metal ions from wastewater.

  8. Hierarchical auxetic mechanical metamaterials.

    Science.gov (United States)

    Gatt, Ruben; Mizzi, Luke; Azzopardi, Joseph I; Azzopardi, Keith M; Attard, Daphne; Casha, Aaron; Briffa, Joseph; Grima, Joseph N

    2015-02-11

    Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.

  9. Hierarchical Auxetic Mechanical Metamaterials

    Science.gov (United States)

    Gatt, Ruben; Mizzi, Luke; Azzopardi, Joseph I.; Azzopardi, Keith M.; Attard, Daphne; Casha, Aaron; Briffa, Joseph; Grima, Joseph N.

    2015-02-01

    Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.

  10. Cosmology and Astrophysics from Relaxed Galaxy Clusters V: Consistency with Cold Dark Matter Structure Formation

    CERN Document Server

    Mantz, Adam B; Morris, R Glenn

    2016-01-01

    This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the Cold Dark Matter (CDM) paradigm. We present constraints on the concentration--mass relation for massive clusters, finding a power-law mass dependence with a slope of $\\kappa_m=-0.16\\pm0.07$, in agreement with CDM predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with $1+z$ of $\\kappa_\\zeta=-0.17\\pm0.26$), with an intrinsic scatter of $\\sigma_{\\ln c}=0.16\\pm0.03$. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically $\\sim50$kpc--1Mpc), and test for departures from the simple Navarro, Frenk & White (NFW...

  11. On Dowell's simplification for acoustic cavity-structure interaction and consistent alternatives.

    Science.gov (United States)

    Ginsberg, Jerry H

    2010-01-01

    A widely employed description of the acoustical response in a cavity whose walls are compliant, which was first proposed by Dowell and Voss [(1962). AIAA J. 1, 476-477], uses the modes of the corresponding cavity with rigid walls as basis functions for a series representation of the pressure. It yields a velocity field that is not compatible with the movement of the boundary, and the system equations do not satisfy the principle of reciprocity. The simplified formulation is compared to consistent solutions of the coupled field equations in the time and frequency domains. In addition, this paper introduces an extension of the Ritz series method to fluid-structure coupled systems that satisfies all continuity conditions by imposing constraint equations to enforce any such conditions that are not identically satisfied by the series. A slender waveguide terminated by an oscillator is analyzed by each method. The simplified formulation is found to be very accurate for light fluid loading, except for the pressure field at frequencies below the fundamental rigid-cavity resonance, whereas the Ritz series solution is found to be extremely accurate in all cases.

  12. The Czech audit: internal consistency, latent structure and identification of risky alcohol consumption.

    Science.gov (United States)

    Sovinová, Hana; Csémy, Ladislav

    2010-09-01

    The primary aim of the study is to examine the psychometric properties and the structure of the Czech version of the Alcohol Use Disorders Identification Test (AUDIT), and to estimate the rate of risky, harmful and problematic alcohol consumers. Two large data sets were analyzed. The first was based on the application of the AUDIT as a part of a general population survey (N = 1.326; age range 18-64), the second represents data gathered by general practitioners (GPs) in the context of a pilot screening and brief advice (SBA) project in the area of Greater Prague (N = 2.589). Analyses of reliability showed satisfying internal consistency of the AUDIT (Cronbach's alpha = 0.83 for population survey and 0.77 for survey based on SBA). Principal component analyses suggest two factor solutions where one factor represents drinking patterns and the second alcohol-related problems or symptoms of dependence. The principal component analyses of both data sets led to similar factor formation. A total of 19% of the general population sample was classified as risky or harmful drinkers and 2% as problem drinkers. These figures were slightly lower in the sample of patients of general practitioners. The Czech version of the AUDIT seems to be a plausible screening instrument. The properties of the instrument suggest usefulness of the summary score for identification of the level of risk.

  13. A novel 3D structure composed of strings of hierarchical TiO{sub 2} spheres formed on TiO{sub 2} nanobelts with high photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yongjian [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Li, Meicheng, E-mail: mcli@ncepu.edu.cn [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Suzhou Institute, North China Electric Power University, Suzhou 215123 (China); Song, Dandan; Li, Xiaodan; Yu, Yue [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China)

    2014-03-15

    A novel hierarchical titanium dioxide (TiO{sub 2}) composite nanostructure with strings of anatase TiO{sub 2} hierarchical micro-spheres and rutile nanobelts framework (TiO{sub 2} HSN) is successfully synthesized via a one-step hydrothermal method. Particularly, the strings of hierarchical spheres are assembled by very thin TiO{sub 2} nanosheets, which are composed of highly crystallized anatase nanocrystals. Meanwhile, the HSN has a large surface area of 191 m{sup 2}/g, which is about 3 times larger than Degussa P25. More importantly, the photocatalytic activity of HSN and P25 were evaluated by the photocatalytic oxidation decomposition of methyl orange (MO) under UV light illumination, and the TiO{sub 2} HSN shows enhanced photocatalytic activity compared with Degussa P25, as result of its continuous hierarchical structures, special conductive channel and large specific surface area. With these features, the hierarchical TiO{sub 2} may have more potential applications in the fields of dye-sensitized solar cells and lithium ion batteries. -- Graphical abstract: Novel TiO{sub 2} with anatase micro-spheres and rutile nanobelts is synthesized. Enhanced photocatalysis is attributed to hierarchical structures (3D spheres), conductive channel (1D nanobelts) and large specific surface area (2D nanosheet). Highlights: • The novel TiO{sub 2} nanostructure (HSN) is fabricated for the first time. • HSN is composed of strings of anatase hierarchical spheres and rutile nanobelt. • HSN presents a larger S{sub BET} of 191 m{sup 2}/g, 3 times larger than the Degussa P25 (59 m{sup 2}/g). • HSN owns three kinds of dimensional TiO{sub 2} (1D, 2D and 3D) simultaneously. • HSN exhibits better photocatalytic performance compared with Degussa P25.

  14. Student conceptions about the DNA structure within a hierarchical organizational level: Improvement by experiment- and computer-based outreach learning.

    Science.gov (United States)

    Langheinrich, Jessica; Bogner, Franz X

    2015-01-01

    As non-scientific conceptions interfere with learning processes, teachers need both, to know about them and to address them in their classrooms. For our study, based on 182 eleventh graders, we analyzed the level of conceptual understanding by implementing the "draw and write" technique during a computer-supported gene technology module. To give participants the hierarchical organizational level which they have to draw, was a specific feature of our study. We introduced two objective category systems for analyzing drawings and inscriptions. Our results indicated a long- as well as a short-term increase in the level of conceptual understanding and in the number of drawn elements and their grades concerning the DNA structure. Consequently, we regard the "draw and write" technique as a tool for a teacher to get to know students' alternative conceptions. Furthermore, our study points the modification potential of hands-on and computer-supported learning modules.

  15. A Decentralized Approach to the Formulation of Hypotheses: A Hierarchical Structural Model for a Prion Self-Assembled System

    Science.gov (United States)

    Wang, Mingyang; Zhang, Feifei; Song, Chao; Shi, Pengfei; Zhu, Jin

    2016-07-01

    Innovation in hypotheses is a key transformative driver for scientific development. The conventional centralized hypothesis formulation approach, where a dominant hypothesis is typically derived from a primary phenomenon, can, inevitably, impose restriction on the range of conceivable experiments and legitimate hypotheses, and ultimately impede understanding of the system of interest. We report herein the proposal of a decentralized approach for the formulation of hypotheses, through initial preconception-free phenomenon accumulation and subsequent reticular logical reasoning processes. The two-step approach can provide an unbiased, panoramic view of the system and as such should enable the generation of a set of more coherent and therefore plausible hypotheses. As a proof-of-concept demonstration of the utility of this open-ended approach, a hierarchical model has been developed for a prion self-assembled system, allowing insight into hitherto elusive static and dynamic features associated with this intriguing structure.

  16. A novel 300 kW arc plasma inverter system based on hierarchical controlled building block structure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To date, the high power arc plasma technology is widely used. A next generation high power arc plasma system based on building block structure is presented. The whole arc plasma inverter system is composed of 12 paralleled units to increase the system output capability. The hierarchical control system is adopted to improve the reliability and flexibility of the high power arc plasma inverter. To ensure the reliable turn on and off of the IGBT module in each building block unit, a special pulse drive circuit is designed by using pulse transformer. The experimental result indicates that the high power arc plasma inverter system can transfer 300 kW arc plasma energy reliably with high efficiency.

  17. Development of hierarchical structures for actions and motor imagery: a constructivist view from synthetic neuro-robotics study.

    Science.gov (United States)

    Nishimoto, Ryunosuke; Tani, Jun

    2009-07-01

    The current paper shows a neuro-robotics experiment on developmental learning of goal-directed actions. The robot was trained to predict visuo-proprioceptive flow of achieving a set of goal-directed behaviors through iterative tutor training processes. The learning was conducted by employing a dynamic neural network model which is characterized by their multiple time-scale dynamics. The experimental results showed that functional hierarchical structures emerge through stages of developments where behavior primitives are generated in earlier stages and their sequences of achieving goals appear in later stages. It was also observed that motor imagery is generated in earlier stages compared to actual behaviors. Our claim that manipulatable inner representation should emerge through the sensory-motor interactions is corresponded to Piaget's constructivist view.

  18. RedeR: R/Bioconductor package for representing modular structures, nested networks and multiple levels of hierarchical associations.

    Science.gov (United States)

    Castro, Mauro A A; Wang, Xin; Fletcher, Michael N C; Meyer, Kerstin B; Markowetz, Florian

    2012-04-24

    Visualization and analysis of molecular networks are both central to systems biology. However, there still exists a large technological gap between them, especially when assessing multiple network levels or hierarchies. Here we present RedeR, an R/Bioconductor package combined with a Java core engine for representing modular networks. The functionality of RedeR is demonstrated in two different scenarios: hierarchical and modular organization in gene co-expression networks and nested structures in time-course gene expression subnetworks. Our results demonstrate RedeR as a new framework to deal with the multiple network levels that are inherent to complex biological systems. RedeR is available from http://bioconductor.org/packages/release/bioc/html/RedeR.html.

  19. Formation of Hierarchical Structure Composed of (Co/Ni)Mn-LDH Nanosheets on MWCNT Backbones for Efficient Electrocatalytic Water Oxidation.

    Science.gov (United States)

    Jia, Gan; Hu, Yingfei; Qian, Qinfeng; Yao, Yingfang; Zhang, Shiying; Li, Zhaosheng; Zou, Zhigang

    2016-06-15

    Active, stable, and cost-effective electrocatalysts are attractive alternatives to the noble metal oxides that have been used in water splitting. The direct nucleation and growth of electrochemically active LDH materials on chemically modified MWCNTs exhibit considerable electrocatalytic activity toward oxygen evolution from water oxidation. CoMn-based and NiMn-based hybrids were synthesized using a facile chemical bath deposition method and the as-synthesized materials exhibited three-dimensional hierarchical configurations with tunable Co/Mn and Ni/Mn ratio. Benefiting from enhanced electrical conductivity with MWCNT backbones and LDH lamellar structure, the Co5Mn-LDH/MWCNT and Ni5Mn-LDH/MWCNT could generated a current density of 10 mA cm(-2) at overpotentials of ∼300 and ∼350 mV, respectively, in 1 M KOH. In addition, the materials also exhibited outstanding long-term electrocatalytic stability.

  20. Hierarchical-structured anatase-titania/cellulose composite sheet with high photocatalytic performance and antibacterial activity.

    Science.gov (United States)

    Luo, Yan; Huang, Jianguo

    2015-02-02

    Bulk hierarchical anatase-titania/cellulose composite sheets were fabricated by subjecting an ultrathin titania gel film pre-deposited filter paper to a solvo-co-hydrothermal treatment by using titanium butoxide as the precursor to grow anatase-titania nanocrystallites on the cellulose nanofiber surfaces. The titanium butoxide specie is firstly absorbed onto the nanofibers of the cellulose substance through a solvothermal process, which was thereafter hydrolyzed and crystallized upon the subsequent hydrothermal treatment, leading to the formation of fine anatase-titania nanoparticles with sizes of 2-5 nm uniformly anchored on the cellulose nanofibers. The resulting anatase-titania/cellulose composite sheet shows a significant photocatalytic performance towards degradation of a methylene blue dye, and introduction of silver nanoparticles into the composite sheet yields an Ag-NP/anatase-titania/cellulose composite material possessing excellent antibacterial activity against both Gram-positive and Gram-negative bacteria. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Hierarchical particle swarm optimizer for minimizing the non-convex potential energy of molecular structure.

    Science.gov (United States)

    Cheung, Ngaam J; Shen, Hong-Bin

    2014-11-01

    The stable conformation of a molecule is greatly important to uncover the secret of its properties and functions. Generally, the conformation of a molecule will be the most stable when it is of the minimum potential energy. Accordingly, the determination of the conformation can be solved in the optimization framework. It is, however, not an easy task to achieve the only conformation with the lowest energy among all the potential ones because of the high complexity of the energy landscape and the exponential computation increasing with molecular size. In this paper, we develop a hierarchical and heterogeneous particle swarm optimizer (HHPSO) to deal with the problem in the minimization of the potential energy. The proposed method is evaluated over a scalable simplified molecular potential energy function with up to 200 degrees of freedom and a realistic energy function of pseudo-ethane molecule. The experimental results are compared with other six PSO variants and four genetic algorithms. The results show HHPSO is significantly better than the compared PSOs with p-value less than 0.01277 over molecular potential energy function.

  2. Enhancing the Discrete Particle Swarm Optimization based Workflow Grid Scheduling using Hierarchical Structure

    Directory of Open Access Journals (Sweden)

    Ritu Garg

    2013-05-01

    Full Text Available The problem of scheduling dependent tasks (DAG is an important version of scheduling, to efficiently exploit the computational capabilities of grid systems. The problem of scheduling tasks of a graph onto a set of different machines is an NP Complete problem. As a result, a number of heuristic and meta-heuristic approaches are used over the years due to their ability of providing high quality solutions with reasonable computation time. Discrete Particle Swarm Optimization is one such meta-heuristic used for solving the discrete problem of grid scheduling, but this method converge to sub optimal solutions due to premature convergence. To deal with premature convergence, in this paper we proposed the design and implementation of hierarchical discrete particle swarm optimization (H-DPSO for dependent task scheduling in grid environment. In H-DPSO particles are arranged in dynamic hierarchy where good particles lying above in hierarchy are having larger influence on the swarm. We consider the bi-objective version of problem to minimize makespan and total cost simultaneously as the optimization criteria. The H-DPSO based scheduler was evaluated under different application task graphs. Simulation analysis manifests that H-DPSO based scheduling is highly viable and effective approach for grid computing.

  3. Linking lipid architecture to bilayer structure and mechanics using self-consistent field modelling

    Energy Technology Data Exchange (ETDEWEB)

    Pera, H.; Kleijn, J. M.; Leermakers, F. A. M., E-mail: Frans.leermakers@wur.nl [Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6307 HB Wageningen (Netherlands)

    2014-02-14

    To understand how lipid architecture determines the lipid bilayer structure and its mechanics, we implement a molecularly detailed model that uses the self-consistent field theory. This numerical model accurately predicts parameters such as Helfrichs mean and Gaussian bending modulus k{sub c} and k{sup ¯} and the preferred monolayer curvature J{sub 0}{sup m}, and also delivers structural membrane properties like the core thickness, and head group position and orientation. We studied how these mechanical parameters vary with system variations, such as lipid tail length, membrane composition, and those parameters that control the lipid tail and head group solvent quality. For the membrane composition, negatively charged phosphatidylglycerol (PG) or zwitterionic, phosphatidylcholine (PC), and -ethanolamine (PE) lipids were used. In line with experimental findings, we find that the values of k{sub c} and the area compression modulus k{sub A} are always positive. They respond similarly to parameters that affect the core thickness, but differently to parameters that affect the head group properties. We found that the trends for k{sup ¯} and J{sub 0}{sup m} can be rationalised by the concept of Israelachivili's surfactant packing parameter, and that both k{sup ¯} and J{sub 0}{sup m} change sign with relevant parameter changes. Although typically k{sup ¯}<0, membranes can form stable cubic phases when the Gaussian bending modulus becomes positive, which occurs with membranes composed of PC lipids with long tails. Similarly, negative monolayer curvatures appear when a small head group such as PE is combined with long lipid tails, which hints towards the stability of inverse hexagonal phases at the cost of the bilayer topology. To prevent the destabilisation of bilayers, PG lipids can be mixed into these PC or PE lipid membranes. Progressive loading of bilayers with PG lipids lead to highly charged membranes, resulting in J{sub 0}{sup m}≫0, especially at low ionic

  4. On the consistency of Monte Carlo track structure DNA damage simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pater, Piotr, E-mail: piotr.pater@mail.mcgill.ca; Seuntjens, Jan; El Naqa, Issam [McGill University, Montreal, Quebec H3G 1A4 (Canada); Bernal, Mario A. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, Campinas 13083-859 (Brazil)

    2014-12-15

    Purpose: Monte Carlo track structures (MCTS) simulations have been recognized as useful tools for radiobiological modeling. However, the authors noticed several issues regarding the consistency of reported data. Therefore, in this work, they analyze the impact of various user defined parameters on simulated direct DNA damage yields. In addition, they draw attention to discrepancies in published literature in DNA strand break (SB) yields and selected methodologies. Methods: The MCTS code Geant4-DNA was used to compare radial dose profiles in a nanometer-scale region of interest (ROI) for photon sources of varying sizes and energies. Then, electron tracks of 0.28 keV–220 keV were superimposed on a geometric DNA model composed of 2.7 × 10{sup 6} nucleosomes, and SBs were simulated according to four definitions based on energy deposits or energy transfers in DNA strand targets compared to a threshold energy E{sub TH}. The SB frequencies and complexities in nucleosomes as a function of incident electron energies were obtained. SBs were classified into higher order clusters such as single and double strand breaks (SSBs and DSBs) based on inter-SB distances and on the number of affected strands. Results: Comparisons of different nonuniform dose distributions lacking charged particle equilibrium may lead to erroneous conclusions regarding the effect of energy on relative biological effectiveness. The energy transfer-based SB definitions give similar SB yields as the one based on energy deposit when E{sub TH} ≈ 10.79 eV, but deviate significantly for higher E{sub TH} values. Between 30 and 40 nucleosomes/Gy show at least one SB in the ROI. The number of nucleosomes that present a complex damage pattern of more than 2 SBs and the degree of complexity of the damage in these nucleosomes diminish as the incident electron energy increases. DNA damage classification into SSB and DSB is highly dependent on the definitions of these higher order structures and their

  5. Three Ways to Link Merge with Hierarchical Concept-Combination

    Directory of Open Access Journals (Sweden)

    Chris Thornton

    2016-11-01

    Full Text Available In the Minimalist Program, language competence is seen to stem from a fundamental ability to construct hierarchical structure, an operation dubbed ‘Merge’. This raises the problem of how to view hierarchical concept-combination. This is a conceptual operation which also builds hierarchical structure. We can conceive of a garden that consists of a lawn and a flower-bed, for example, or a salad consisting of lettuce, fennel and rocket, or a crew consisting of a pilot and engineer. In such cases, concepts are put together in a way that makes one the accommodating element with respect to the others taken in combination. The accommodating element becomes the root of a hierarchical unit. Since this unit is itself a concept, the operation is inherently recursive. Does this mean the mind has two independent systems of hierarchical construction? Or is some form of integration more likely? Following a detailed examination of the operations involved, this paper shows there are three main ways in which Merge might be linked to hierarchical concept-combination. Also examined are the architectural implications that arise in each case.

  6. How hierarchical is language use?

    Science.gov (United States)

    Frank, Stefan L.; Bod, Rens; Christiansen, Morten H.

    2012-01-01

    It is generally assumed that hierarchical phrase structure plays a central role in human language. However, considerations of simplicity and evolutionary continuity suggest that hierarchical structure should not be invoked too hastily. Indeed, recent neurophysiological, behavioural and computational studies show that sequential sentence structure has considerable explanatory power and that hierarchical processing is often not involved. In this paper, we review evidence from the recent literature supporting the hypothesis that sequential structure may be fundamental to the comprehension, production and acquisition of human language. Moreover, we provide a preliminary sketch outlining a non-hierarchical model of language use and discuss its implications and testable predictions. If linguistic phenomena can be explained by sequential rather than hierarchical structure, this will have considerable impact in a wide range of fields, such as linguistics, ethology, cognitive neuroscience, psychology and computer science. PMID:22977157

  7. How hierarchical is language use?

    Science.gov (United States)

    Frank, Stefan L; Bod, Rens; Christiansen, Morten H

    2012-11-22

    It is generally assumed that hierarchical phrase structure plays a central role in human language. However, considerations of simplicity and evolutionary continuity suggest that hierarchical structure should not be invoked too hastily. Indeed, recent neurophysiological, behavioural and computational studies show that sequential sentence structure has considerable explanatory power and that hierarchical processing is often not involved. In this paper, we review evidence from the recent literature supporting the hypothesis that sequential structure may be fundamental to the comprehension, production and acquisition of human language. Moreover, we provide a preliminary sketch outlining a non-hierarchical model of language use and discuss its implications and testable predictions. If linguistic phenomena can be explained by sequential rather than hierarchical structure, this will have considerable impact in a wide range of fields, such as linguistics, ethology, cognitive neuroscience, psychology and computer science.

  8. New bio-ceramization processes applied to vegetable hierarchical structures for bone regeneration: an experimental model in sheep.

    Science.gov (United States)

    Filardo, Giuseppe; Kon, Elizaveta; Tampieri, Anna; Cabezas-Rodríguez, Rafael; Di Martino, Alessandro; Fini, Milena; Giavaresi, Gianluca; Lelli, Marco; Martínez-Fernández, Julian; Martini, Lucia; Ramírez-Rico, Joaquin; Salamanna, Francesca; Sandri, Monica; Sprio, Simone; Marcacci, Maurilio

    2014-02-01

    Bone loss is still a major problem in orthopedics. The purpose of this experimental study is to evaluate the safety and regenerative potential of a new scaffold based on a bio-ceramization process for bone regeneration in long diaphyseal defects in a sheep model. The scaffold was obtained by transformation of wood pieces into porous biomorphic silicon carbide (BioSiC®). The process enabled the maintenance of the original wood microstructure, thus exhibiting hierarchically organized porosity and high mechanical strength. To improve cell adhesion and osseointegration, the external surface of the hollow cylinder was made more bioactive by electrodeposition of a uniform layer of collagen fibers that were mineralized with biomimetic hydroxyapatite, whereas the internal part was filled with a bio-hybrid HA/collagen composite. The final scaffold was then implanted in the metatarsus of 15 crossbred (Merinos-Sarda) adult sheep, divided into 3 groups: scaffold alone, scaffold with platelet-rich plasma (PRP) augmentation, and scaffold with bone marrow stromal cells (BMSCs) added during implantation. Radiological analysis was performed at 4, 8, 12 weeks, and 4 months, when animals were sacrificed for the final radiological, histological, and histomorphometric evaluation. In all tested treatments, these analyses highlighted the presence of newly formed bone at the bone scaffolds' interface. Although a lack of substantial effect of PRP was demonstrated, the scaffold+BMSC augmentation showed the highest value of bone-to-implant contact and new bone growth inside the scaffold. The findings of this study suggest the potential of bio-ceramization processes applied to vegetable hierarchical structures for the production of wood-derived bone scaffolds, and document a suitable augmentation procedure in enhancing bone regeneration, particularly when combined with BMSCs.

  9. Boosted Supercapacitive Energy with High Rate Capability of aCarbon Framework with Hierarchical Pore Structure in an Ionic Liquid.

    Science.gov (United States)

    Wang, Xuehang; Zhou, Haitao; Lou, Fengliu; Li, Yahao; Buan, Marthe E M; Duan, Xuezhi; Walmsley, John C; Sheridan, Edel; Chen, De

    2016-11-09

    The specific energy of a supercapacitor (SC) with an ionic liquid (IL)-based electrolyte is larger than that using an aqueous electrolyte owing to the wide operating voltage window provided by the IL. However, the wide-scale application of high-energy SCs using ILs is limited owing to a serious reduction of the energy with increasing power. The introduction of macropores to the porous material can mitigate the reduction in the gravimetric capacitance at high rates, but this lowers the volumetric capacitance. Synthetic polymers can be used to obtain macroporous frameworks with high apparent densities, but the preservation of the frameworks during activation is challenging. To simultaneously achieve high gravimetric capacitance, volumetric capacitance, and rate capability, a systematic strategy was used to synthesize a densely knitted carbon framework with a hierarchical pore structure by using a polymer. The energy of the SC using the hierarchically porous carbon was 160 Wh kg(-1) and 85 Wh L(-1) on an active material base at a power of 100 W kg(-1) in an IL electrolyte, and 60 % of the energy was still retained at a power larger than 5000 W kg(-1) . To illustrate, a full-packaged SC with the material could store/release energy comparable to a Ni-metal hydride battery (gravimetrically) and one order of magnitude higher than a commercial carbon-based SC (volumetrically), within one minute. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Fukunaga-Koontz feature transformation for statistical structural damage detection and hierarchical neuro-fuzzy damage localisation

    Science.gov (United States)

    Hoell, Simon; Omenzetter, Piotr

    2017-07-01

    Considering jointly damage sensitive features (DSFs) of signals recorded by multiple sensors, applying advanced transformations to these DSFs and assessing systematically their contribution to damage detectability and localisation can significantly enhance the performance of structural health monitoring systems. This philosophy is explored here for partial autocorrelation coefficients (PACCs) of acceleration responses. They are interrogated with the help of the linear discriminant analysis based on the Fukunaga-Koontz transformation using datasets of the healthy and selected reference damage states. Then, a simple but efficient fast forward selection procedure is applied to rank the DSF components with respect to statistical distance measures specialised for either damage detection or localisation. For the damage detection task, the optimal feature subsets are identified based on the statistical hypothesis testing. For damage localisation, a hierarchical neuro-fuzzy tool is developed that uses the DSF ranking to establish its own optimal architecture. The proposed approaches are evaluated experimentally on data from non-destructively simulated damage in a laboratory scale wind turbine blade. The results support our claim of being able to enhance damage detectability and localisation performance by transforming and optimally selecting DSFs. It is demonstrated that the optimally selected PACCs from multiple sensors or their Fukunaga-Koontz transformed versions can not only improve the detectability of damage via statistical hypothesis testing but also increase the accuracy of damage localisation when used as inputs into a hierarchical neuro-fuzzy network. Furthermore, the computational effort of employing these advanced soft computing models for damage localisation can be significantly reduced by using transformed DSFs.

  11. Hierarchical photocatalysts.

    Science.gov (United States)

    Li, Xin; Yu, Jiaguo; Jaroniec, Mietek

    2016-05-01

    As a green and sustainable technology, semiconductor-based heterogeneous photocatalysis has received much attention in the last few decades because it has potential to solve both energy and environmental problems. To achieve efficient photocatalysts, various hierarchical semiconductors have been designed and fabricated at the micro/nanometer scale in recent years. This review presents a critical appraisal of fabrication methods, growth mechanisms and applications of advanced hierarchical photocatalysts. Especially, the different synthesis strategies such as two-step templating, in situ template-sacrificial dissolution, self-templating method, in situ template-free assembly, chemically induced self-transformation and post-synthesis treatment are highlighted. Finally, some important applications including photocatalytic degradation of pollutants, photocatalytic H2 production and photocatalytic CO2 reduction are reviewed. A thorough assessment of the progress made in photocatalysis may open new opportunities in designing highly effective hierarchical photocatalysts for advanced applications ranging from thermal catalysis, separation and purification processes to solar cells.

  12. Ca(II) doped β-In2S3 hierarchical structures for photocatalytic hydrogen generation and organic dye degradation under visible light irradiation.

    Science.gov (United States)

    Yang, Shuang; Xu, Cheng-Yan; Zhang, Bao-You; Yang, Li; Hu, Sheng-Peng; Zhen, Liang

    2017-04-01

    Hierarchical structures assembled by two-dimensional (2D) nanosheets could inherit the characteristics of nanosheets and acquire additional advantages from the unique secondary architectures, which would have important influences on the photocatalytic properties of semiconductor nanomaterials. In this work, we successfully synthesized Ca(II) doped β-In2S3 hierarchical structures stacked by thin nanosheets by a simple solution chemical process. The effects of reaction temperature and Ca(2+) concentration on the size and morphology of the products were systematically investigated. The photocatalytic applications of the β-In2S3 hierarchical structures were evaluated for hydrogen production and degradation of Rhodamine B (RhB) under visible light irradiation (λ>420nm). The β-In2S3 hierarchical structures showed promising activity towards photocatalytic hydrogen production (145.0μmolg(-1)h(-1)) and RhB solution (1×10(-5)M) was completely degraded within 100min under visible light irradiation.

  13. Robust synthesis of green fuels from biomass-derived ethyl esters over a hierarchically core/shell-structured ZSM-5@(Co/SiO2) catalyst.

    Science.gov (United States)

    Wang, Darui; Wang, Bo; Ding, Yu; Yuan, Qingqing; Wu, Haihong; Guan, Yejun; Wu, Peng

    2017-09-12

    A novel bifunctional ZSM-5@(Co/SiO2) material with a hierarchical core/shell structure was successfully prepared through a simple chemoselective interaction between the crystal surface silica species of zeolite and the external Co(2+) source in basic media, which served as an excellent catalyst in the synthesis of green fuels from biomass-derived ethyl esters.

  14. Self-Concepts in Reading, Writing, Listening, and Speaking: A Multidimensional and Hierarchical Structure and Its Generalizability across Native and Foreign Languages

    Science.gov (United States)

    Arens, A. Katrin; Jansen, Malte

    2016-01-01

    Academic self-concept has been conceptualized as a multidimensional and hierarchical construct. Previous research has mostly focused on its multidimensionality, distinguishing between verbal and mathematical self-concept domains, and only a few studies have examined the factorial structure within specific self-concept domains. The present study…

  15. Synthesis and microwave absorption enhancement of graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures.

    Science.gov (United States)

    Wang, Lei; Huang, Ying; Sun, Xu; Huang, Haijian; Liu, Panbo; Zong, Meng; Wang, Yan

    2014-03-21

    Hierarchical structures of graphene@Fe3O4@SiO2@NiO nanosheets were prepared by combining the versatile sol-gel process with a hydrothermal reaction. Graphene@Fe3O4 composites were first synthesized by the reduction reaction between FeCl3 and diethylene glycol (DEG) in the presence of GO. Then, graphene@Fe3O4 was coated with SiO2 to obtain graphene@Fe3O4@SiO2. Finally, NiO nanosheets were grown perpendicularly on the surface of graphene@Fe3O4@SiO2 and graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures were formed. Moreover, the microwave absorption properties of both graphene@Fe3O4 and graphene@Fe3O4@SiO2@NiO nanosheets were investigated between 2 and 18 GHz microwave frequency bands. The electromagnetic data demonstrate that graphene@Fe3O4@SiO2@NiO nanosheet hierarchical structures exhibit significantly enhanced microwave absorption properties compared with graphene@Fe3O4, which probably originate from the unique hierarchical structure with a large surface area and high porosity.

  16. Investigating the Hierarchical Factor Structure of the Fifth Edition of the 16PF: An Application of the Schmid-Leiman Orthogonalization Procedure.

    Science.gov (United States)

    Chernyshenko, Oleksandr S.; Stark, Stephen; Chan, Kim Yin

    2001-01-01

    Studied the unidimensionality of the 16 noncognitive scales of the Sixteen Personality Factor Questionnaire (16PF) and the hierarchical factor structure of the inventory. Results using the Schmid Leiman orthogonalization procedure (J. Schmid and J. Leiman, 1957) showed that the noncognitive multi-item composites could be factored into 16…

  17. Hierarchically Nanoporous Bioactive Glasses for High Efficiency Immobilization of Enzymes

    DEFF Research Database (Denmark)

    He, W.; Min, D.D.; Zhang, X.D.

    2014-01-01

    Bioactive glasses with hierarchical nanoporosity and structures have been heavily involved in immobilization of enzymes. Because of meticulous design and ingenious hierarchical nanostructuration of porosities from yeast cell biotemplates, hierarchically nanostructured porous bioactive glasses can...

  18. Hierarchical Cantor set in the large scale structure with torus geometry

    Energy Technology Data Exchange (ETDEWEB)

    Murdzek, R. [Physics Department, ' Al. I. Cuza' University, Blvd. Carol I, Nr. 11, Iassy 700506 (Romania)], E-mail: rmurdzek@yahoo.com

    2008-12-15

    The formation of large scale structures is considered within a model with string on toroidal space-time. Firstly, the space-time geometry is presented. In this geometry, the Universe is represented by a string describing a torus surface. Thereafter, the large scale structure of the Universe is derived from the string oscillations. The results are in agreement with the cellular structure of the large scale distribution and with the theory of a Cantorian space-time.

  19. Time-Dependent Wetting Behavior of PDMS Surfaces with Bio-Inspired, Hierarchical Structures

    KAUST Repository

    Mishra, Himanshu

    2015-12-28

    Wetting of rough surfaces involves time-dependent effects, such as surface deformations, non-uniform filling of surface pores within or outside the contact area, and surface chemistries, but the detailed impact of these phenomena on wetting is not entirely clear. Understanding these effects is crucial for designing coatings for a wide range of applications, such as membrane-based oil-water separation and desalination, waterproof linings/windows for automobiles, aircrafts, and naval vessels, and antibiofouling. Herein, we report on time-dependent contact angles of water droplets on a rough polydimethylsiloxane (PDMS) surface that cannot be completely described by the conventional Cassie-Baxter or Wenzel models or the recently proposed Cassie-impregnated model. Shells of sand dollars (Dendraster excentricus) were used as lithography-free, robust templates to produce rough PDMS surfaces with hierarchical, periodic features ranging from 10-7-10-4 m. Under saturated vapor conditions, we found that in the short-term (<1 min), the contact angle of a sessile water droplet on the templated PDMS, θSDT = 140° ± 3°, was accurately described by the Cassie-Baxter model (predicted θSDT = 137°); however, after 90 min, θSDT fell to 110°. Fluorescent confocal microscopy confirmed that the initial reduction in θSDT to 110° (the Wenzel limit) was primarily a Cassie-Baxter to Wenzel transition during which pores within the contact area filled gradually, and more rapidly for ethanol-water mixtures. After 90 min, the contact line of the water droplet became pinned, perhaps caused by viscoelastic deformation of the PDMS around the contact line, and a significant volume of water began to flow from the droplet to pores outside the contact region, causing θSDT to decrease to 65° over 48 h on the rough surface. The system we present here to explore the concept of contact angle time dependence (dynamics) and modeling of natural surfaces provides insights into the design and

  20. High Thermoelectric Performance Lead Selenide Materials through All-scale Hierarchical Structuring

    Science.gov (United States)

    Lee, Yeseul

    Industries have paid increasing attention to power generation using waste heat through thermoelectrics, which convert heat to electric energy. This method can be used in renewable applications because of its environmentally friendly process. Large-scale production of bulk materials with high thermoelectric figure of merit (ZT) is the key to practical applications. PbTe-based materials have been mostly studied, but are facing a challenge regarding scarcity of Te. PbSe is a more abundant analog of PbTe that has been less frequently studied. This work presents a synthesis and characterization of bulk thermoelectric materials based on both n- and p-type PbSe with atomic-, nano-, meso-scale architectures. When PbSe is doped with Ga and In they efficiently generate electron carriers that are sufficient for high ZT. Thus, higher ZT of n-type PbSe can be achieved than that of optimized n-type PbTe at high temperatures. The study of the thermoelectric properties of p-type PbSe with Li, Na, and K indicates that the efficiency of Na in doping PbSe is found to be the highest. The additional spark plasma sintering (SPS) process allows samples to have increased carrier density and produce mesoscale grains that reduce lattice thermal conductivity, increasing ZT. Additional studies for reducing lattice thermal conductivity through nanostructuring were conducted. Adding (Ca/Sr/Ba)Se and EuSe to Na doped SPS PbSe generates nanoprecipitates. This study shows that the hierarchical architecture on the atomic scale (Na and Ca/Sr/Ba/Eu solid solution), nanoscale (MSe/EuSe nanoprecipitates), and mesoscale (grains) effectively increases ZT. MSe samples show no appreciable change in charge transport, while EuSe samples show decreased charge carriers. However, adding more Na optimizes properties. Continued investigating n-type dopants with Sb and Bi shows that Sb not only plays the role as a dopant but also is unexpectedly effective in generating nanostructuring. The Sb-rich precipitates

  1. Fabrication of ZnO/SnO2 hierarchical structures as the composite photoanodes for efficient CdS/CdSe co-sensitized solar cells

    Science.gov (United States)

    Lin, Yibing; Lin, Yu; Wu, Jihuai; Zhang, Xiaolong; Fang, Biaopeng

    2017-03-01

    The composite photoanodes based on the ZnO/SnO2 hierarchical structures with high photoelectricity properties have been successfully synthesized, and used in the CdS and CdSe quantum dots co-sensitized solar cells (QDSSCs). In this experiment, the ZnO/SnO2 nanoparticles (ZS-NP) and hierarchical nanosheets-based microflowers (ZS-MF) were prepared by the one-step hydrothermal route and the morphologies of the products were controlled by the solvent variation. An improved power conversion efficiency of 4.98% was achieved for the cell based on the ZS-MF composite photoanodes, which showed an increase of 21.8% compared to the ZS-NP photoanodes (4.09%). This result is mainly connected to the unique superiority of the three-dimensional hierarchical microflower nanostructures for light scattering and quantum dots loading, which is responsible for the increase of photocurrent values and eventual PCE.

  2. Pore-structure-mediated hierarchical SAPO-34: Facile synthesis, tunable nanostructure, and catalysis applications for the conversion of dimethyl ether into olefins

    Institute of Scientific and Technical Information of China (English)

    Yu Cui; Qiang Zhang; Jie He; Yao Wang; Fei Wei

    2013-01-01

    Hierarchical cross-like SAPO-34 catalysts with different pore size distributions were obtained via hydrothermal synthesis with polyethylene glycol (PEG) as the mesopore-generating agent.The hierarchical SAPO-34 molecular sieves were characterized using X-ray diffraction,scanning electron microscopy,N2 adsorption-desorption,thermogravimetric analysis,and temperature-programmed NH3 desorption.The cross-like SAPO-34 catalysts exhibited enriched multi-porosity,and the sizes of their mesopores ranged from 10 to 50 nm.Both the mesoporous structures and morphologies of the hierarchical SAPO-34 could be further tuned through adjustments of the amount of PEG used.The as-obtained SAPO-34 showed dramatic catalytic performance in the conversion of dimethyl ether into olefins.A maximum selectivity of olefins of 96% was achieved,which was attributed to the rapid transport of the reactants and products in zeolitic micropores through mesopores.

  3. Mechanism and control of the structural evolution of a polymer solar cell from a bulk heterojunction to a thermally unstable hierarchical structure.

    Science.gov (United States)

    Chen, Charn-Ying; Tsao, Cheng-Si; Huang, Yu-Ching; Liu, Hung-Wei; Chiu, Wen-Yen; Chuang, Chih-Min; Jeng, U-Ser; Su, Chun-Jen; Wu, Wei-Ru; Su, Wei-Fang; Wang, Leeyih

    2013-08-21

    We simultaneously employed grazing incidence small-angle and wide-angle X-ray scattering (GISAXS and GIWAXS) techniques to quantitatively study the structural evolution and kinetic behavior of poly(3-hexylthiophene) (P3HT) crystallization, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) aggregation and amorphous P3HT/PCBM domains from a bulk heterojunction (BHJ) to a thermally unstable structure. The independent phase separation regimes on the nanoscale (∼10 nm), mesoscale (∼100 nm) and macroscale (∼μm) are revealed for the first time. Bis-PCBM molecules as inhibitors incorporated into the P3HT/PCBM blend films were adopted as a case study of a control strategy for improving the thermal stability of P3HT/PCBM solar cell. The detailed information on the formation, growth, transformation and mutual interaction between different phases during the hierarchical structural evolution of P3HT/PCBM:xbis-PCBM (x = 8-100%) blend films are presented herein. This systematic study proposes the mechanisms of thermal instability for a polymer/fullerene-based solar cell. We demonstrate a new fundamental concept that the structural evolution and thermal stability of mesoscale amorphous P3HT/PCBM domains during heating are the origin of controlling thermal instability rather than those of nanoscale thermally-stable BHJ structures. It leads to a low-cost and easy-fabrication control strategy for effectively tailoring the hierarchical morphology against thermal instability from molecular to macro scales. The optimum treatment achieving high thermal stability, control of mesoscale domains, can be effectively designed. It is independent of the original BHJ nanostructure design of a polymer/fullerene-based solar cell with high performance. It advances the general knowledge on the thermal instability directly arising from the nanoscale structure.

  4. A Bayesian Approach for Analyzing Hierarchical Data with Missing Outcomes through Structural Equation Models

    Science.gov (United States)

    Song, Xin-Yuan; Lee, Sik-Yum

    2008-01-01

    Structural equation models are widely appreciated in behavioral, social, and psychological research to model relations between latent constructs and manifest variables, and to control for measurement errors. Most applications of structural equation models are based on fully observed data that are independently distributed. However, hierarchical…

  5. Fabrication of semi-transparent superoleophobic thin film from fabrics and nanoparticle-based hierarchical structure

    OpenAIRE

    Nishizawa S.; Shiratori S.

    2013-01-01

    Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain resistant and antifouling materials, and microfluidics among others. Transparency is also desired with superhydrophobicity for their numerous applications; however transparency and oleophobicity are almost incompatible relationship with each other in the point of surface structure. Because oleophobicity required rougher structure at nano-micro scale than hydrophobicity, and these r...

  6. Solvent-free synthesis of nanosized hierarchical sodalite zeolite with a multi-hollow polycrystalline structure

    KAUST Repository

    Zeng, Shangjing

    2016-08-03

    A solvent-free route is developed for preparing nanoscale sodalite zeolite with a multi-hollow structure. Furthermore, the synthesis of nanosized hollow sodalite polycrystalline aggregates with a mesoporous structure and high crystallinity is investigated by adding an organosilane surfactant as a mesopore-generating agent.

  7. Hierarchical Dragonfly Wing: Microstructure-Biomechanical Behavior Relations

    Institute of Scientific and Technical Information of China (English)

    Yinglong Chen; Xishu Wang; Huaihui Ren; Hang Yin; Su Jia

    2012-01-01

    The dragonfly wing,which consists of veins and membrane,is of biological hierarchical material.We observed the cross-sections of longitudinal veins and membrane using Environmental Scanning Electron Microscopy (ESEM).Based on the experiments and previous studies,we described the longitudinal vein and the membrane in terms of two hierarchical levels of organization of composite materials at the micro- and nano-scales.The longitudinal vein of dragonfly wing has a complex sandwich structure with two chitinous shells and a protein layer,and it is considered as the first hierarchical level of the vein.Moreover,the chitinous shells are concentric multilayered structures.Clusters of nano-fibrils grow along the circumferential orientation embedded into the protein layer.It is considered as the second level of the hierarchy.Similarly,the upper and lower epidermises of membrane constitute the first hierarchical level of organization in micro scale.Similar to the vein shell,the membrane epidermises were found to be a paralleled multilayered structure,defined as the second hierarchical level of the membrane.Combining with the mechanical behavior analysis of the dragonfly wing,we concluded that the growth orientation of the hierarchical structure of the longitudinal vein and membrane is relevant to its biomechanical behavior.

  8. Neutrosophic Hierarchical Clustering Algoritms

    Directory of Open Access Journals (Sweden)

    Rıdvan Şahin

    2014-03-01

    Full Text Available Interval neutrosophic set (INS is a generalization of interval valued intuitionistic fuzzy set (IVIFS, whose the membership and non-membership values of elements consist of fuzzy range, while single valued neutrosophic set (SVNS is regarded as extension of intuitionistic fuzzy set (IFS. In this paper, we extend the hierarchical clustering techniques proposed for IFSs and IVIFSs to SVNSs and INSs respectively. Based on the traditional hierarchical clustering procedure, the single valued neutrosophic aggregation operator, and the basic distance measures between SVNSs, we define a single valued neutrosophic hierarchical clustering algorithm for clustering SVNSs. Then we extend the algorithm to classify an interval neutrosophic data. Finally, we present some numerical examples in order to show the effectiveness and availability of the developed clustering algorithms.

  9. Preparation of novel polymer–metal oxide nanocomposites with nanophase separated hierarchical structure

    Indian Academy of Sciences (India)

    K Nam; Y Tsutsumi; C Yoshikawa; Y Tanaka; R Fukaya; T Kimura; H Kobayashi; T Hanawa; A Kishida

    2011-12-01

    This article deals with preparation of nanocomposite which comprised of nanophase separated structure of polymer chains and metal oxide. By grafting poly(hydroxyethyl methacrylate), poly(HEMA) on the surface of titanium which is covered by passive titanium oxide by atom transfer radical polymerization (ATRP) and executing anodic polarization, hierarchy nanophase separated structure with controlled thickness can be obtained. The titanium ions would be cationically charged and completely filled up the unoccupied binding sites of the polymer chains via electrochemical reaction, eventually covering the polymer chains with titanium oxide. However, this structure can be obtained when the anodic polarization is executed at initial applied voltage exceeding 10 VSCE. The control of thickness is possible by controlling the initial applied voltage. These results prove that the conventional polymer can form composite structure with metal oxide without using fillers or special polymers designed for composite.

  10. Self-consistent photonic band structure of dielectric superlattices containing nonlinear optical materials.

    Science.gov (United States)

    Lousse, V; Vigneron, J P

    2001-02-01

    The theory of photonic crystals is extended to include the optical Kerr effect taking place in weak third-order, nonlinear materials present in the unit cell. The influence on the dispersion relations of the illumination caused by a single Bloch mode transiting through the crystal structure is examined. Special attention is given to the modification of the photonic gap width and position. Assuming an instantaneous change of refractive index with illumination, the nonlinear band structure problem is solved as a sequence of ordinary, linear band structure calculations, carried out in a plane-wave field representation.

  11. A hierarchical method for structural topology design problems with local stress and displacement constraints

    DEFF Research Database (Denmark)

    Stolpe, Mathias; Stidsen, Thomas K.

    2005-01-01

    of minimizing the weight of a structure subject to displacement and local design-dependent stress constraints. The method iteratively solves a sequence of problems of increasing size of the same type as the original problem. The problems are defined on a design mesh which is initially coarse...... from global optimization, which have only recently become available, for solving the problems in the sequence. Numerical examples of topology design problems of continuum structures with local stress and displacement constraints are presented....

  12. A hierarchical method for discrete structural topology design problems with local stress and displacement constraints

    DEFF Research Database (Denmark)

    Stolpe, Mathias; Stidsen, Thomas K.

    2007-01-01

    of minimizing the weight of a structure subject to displacement and local design-dependent stress constraints. The method iteratively treats a sequence of problems of increasing size of the same type as the original problem. The problems are defined on a design mesh which is initially coarse...... from global optimization, which have only recently become available, for solving the problems in the sequence. Numerical examples of topology design problems of continuum structures with local stress and displacement constraints are presented....

  13. Facile synthesis of hierarchically structured BiVO4 oriented along (010) facets with different morphologies and their photocatalytic properties

    Science.gov (United States)

    Zhao, Guosheng; Liu, Wei; Li, Jinying; Lv, Qiuyan; Li, Wenxin; Liang, Liting

    2016-12-01

    Hierarchically structured BiVO4 oriented along (010) facets with different morphologies are synthesized by a template-free solvothermal process in glycerol (Gly)-water mixed solvent. The effects of the volume fraction of Gly aqueous solution on the crystal structure, growth degree of (010) facets, morphology and photocatalytic activity were investigated. It is found that the volume fraction of Gly aqueous solution has strong influence on the concentration of the reaction species in the self-assembly process, and consequently induces the different morphology, as well as the crystal growth of the as-prepared BiVO4 oriented along (010) facets. A possible formation mechanism is proposed on the basis of the characterization results of X-ray diffraction and scanning electron microscopy. The four-leaved primrose-like BiVO4 sample exhibits the best photocatalytic activity for the photodegradation of methylene blue (MB) solution under simulated sunlight irradiation. The enhanced photocatalytic activity can be attributed to the improved separation of photogenerated electrons and holes caused by both special morphology and preferential growth of (010) facets.

  14. Synthesis of CaMoO{sub 4} hierarchical structures via a simple slow-release co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Yubin; Song, Jimei, E-mail: jmsongsss@163.com; Hu, Gang; Liu, Ya

    2015-09-15

    Graphical abstract: - Highlights: • Erythrocyte-like CaMoO{sub 4} with uniform shape were successfully synthesized. • The slow-release of MoO{sub 4}{sup 2−} affected the final CaMoO{sub 4} morphology. • Erythrocyte-like CaMoO{sub 4} exhibited high removal rate for the methylene blue. - Abstract: In this paper, erythrocyte-like calcium molybdate (CaMoO{sub 4}) hierarchical structures were successfully synthesized by a modified slow-release strategy. The structure of the as-prepared products was characterized by X-ray diffraction, Fourier transform infrared and Raman spectroscopy. The morphology was observed with scanning electron microscopy. A series of experiments of reaction conditions including reaction time, initial pH and molybdenum source were carefully carried out. The results showed that the slow release of MoO{sub 4}{sup 2−} played a key role in the morphology of the products. Moreover, the photoluminescence spectrum of the erythrocyte-like CaMoO{sub 4} revealed a strong and broad emission peak at 536 nm. The erythrocyte-like CaMoO{sub 4} exhibited high removal rate for the methylene blue (MB), suggesting its potential application in water treatment.

  15. Computational prediction of riboswitch tertiary structures including pseudoknots by RAGTOP: a hierarchical graph sampling approach.

    Science.gov (United States)

    Kim, Namhee; Zahran, Mai; Schlick, Tamar

    2015-01-01

    The modular organization of RNA structure has been exploited in various computational and theoretical approaches to identify RNA tertiary (3D) motifs and assemble RNA structures. Riboswitches exemplify this modularity in terms of both structural and functional adaptability of RNA components. Here, we extend our computational approach based on tree graph sampling to the prediction of riboswitch topologies by defining additional edges to mimick pseudoknots. Starting from a secondary (2D) structure, we construct an initial graph deduced from predicted junction topologies by our data-mining algorithm RNAJAG trained on known RNAs; we sample these graphs in 3D space guided by knowledge-based statistical potentials derived from bending and torsion measures of internal loops as well as radii of gyration for known RNAs. We present graph sampling results for 10 representative riboswitches, 6 of them with pseudoknots, and compare our predictions to solved structures based on global and local RMSD measures. Our results indicate that the helical arrangements in riboswitches can be approximated using our combination of modified 3D tree graph representations for pseudoknots, junction prediction, graph moves, and scoring functions. Future challenges in the field of riboswitch prediction and design are also discussed.

  16. Hierarchical Event Descriptors (HED): Semi-Structured Tagging for Real-World Events in Large-Scale EEG

    Science.gov (United States)

    Bigdely-Shamlo, Nima; Cockfield, Jeremy; Makeig, Scott; Rognon, Thomas; La Valle, Chris; Miyakoshi, Makoto; Robbins, Kay A.

    2016-01-01

    Real-world brain imaging by EEG requires accurate annotation of complex subject-environment interactions in event-rich tasks and paradigms. This paper describes the evolution of the Hierarchical Event Descriptor (HED) system for systematically describing both laboratory and real-world events. HED version 2, first described here, provides the semantic capability of describing a variety of subject and environmental states. HED descriptions can include stimulus presentation events on screen or in virtual worlds, experimental or spontaneous events occurring in the real world environment, and events experienced via one or multiple sensory modalities. Furthermore, HED 2 can distinguish between the mere presence of an object and its actual (or putative) perception by a subject. Although the HED framework has implicit ontological and linked data representations, the user-interface for HED annotation is more intuitive than traditional ontological annotation. We believe that hiding the formal representations allows for a more user-friendly interface, making consistent, detailed tagging of experimental, and real-world events possible for research users. HED is extensible while retaining the advantages of having an enforced common core vocabulary. We have developed a collection of tools to support HED tag assignment and validation; these are available at hedtags.org. A plug-in for EEGLAB (sccn.ucsd.edu/eeglab), CTAGGER, is also available to speed the process of tagging existing studies. PMID:27799907

  17. Hierarchical Event Descriptors (HED: Semi-structured tagging for real-world events in large-scale EEG

    Directory of Open Access Journals (Sweden)

    Nima Bigdely-Shamlo

    2016-10-01

    Full Text Available Real-world brain imaging by EEG requires accurate annotation of complex subject-environment interactions in event-rich tasks and paradigms. This paper describes the evolution of the HED (Hierarchical Event Descriptor system for systematically describing both laboratory and real-world events. HED version 2, first described here, provides the semantic capability of describing a variety of subject and environmental states. HED descriptions can include stimulus presentation events on screen or in virtual worlds, experimental or spontaneous events occurring in the real world environment, and events experienced via one or multiple sensory modalities. Furthermore, HED 2 can distinguish between the mere presence of an object and its actual (or putative perception by a subject. Although the HED framework has implicit ontological and linked data representations, the user-interface for HED annotation is more intuitive than traditional ontological annotation. We believe that hiding the formal representations allows for a more user-friendly interface, making consistent, detailed tagging of experimental and real-world events possible for research users. HED is extensible while retaining the advantages of having an enforced common core vocabulary. We have developed a collection of tools to support HED tag assignment and validation; these are available at hedtags.org. A plug-in for EEGLAB (sccn.ucsd.edu/eeglab, CTAGGER, is also available to speed the process of tagging existing studies.

  18. Biomimetics Bioinspired Hierarchical-Structured Surfaces for Green Science and Technology

    CERN Document Server

    Bhushan, Bharat

    2012-01-01

    This book presents an overview of the general field of biomimetics - lessons from nature. It presents various examples of biomimetics, including roughness-induced superomniphobic surfaces which provide functionality of commercial interest. The major focus in the book is on lotus effect, rose petal effect, shark skin effect, and gecko adhesion.  For each example, the book first presents characterization of an object to understand how a natural object provides functionality, followed by modeling and then fabrication of structures in the lab using nature’s route to verify one’s understanding of nature and provide guidance for development of optimum structures. Once it is understood how nature does it, examples of fabrication of optimum structures using smart materials and fabrication techniques, are presented. Examples of nature inspired objects are also presented throughout.

  19. Vapour sensitivity of an ALD hierarchical photonic structure inspired by Morpho.

    Science.gov (United States)

    Poncelet, Olivier; Tallier, Guillaume; Mouchet, Sébastien R; Crahay, André; Rasson, Jonathan; Kotipalli, Ratan; Deparis, Olivier; Francis, Laurent A

    2016-05-09

    The unique architecture of iridescent Morpho butterfly scales is known to exhibit different optical responses to various vapours. However, the mechanism behind this phenomenon is not fully quantitatively understood. This work reports on process developments in the micro-fabrication of a Morpho-inspired photonic structure in atomic layer deposited (ALD) materials in order to investigate the vapour optical sensitivity of such artificial nanostructures. By developing recipes for dry and wet etching of ALD oxides, we micro-fabricated two structures: one combining Al2O3 and TiO2, and the other combining Al2O3 and HfO2. For the first time, we report the optical response of such ALD Morpho-like structures measured under a controlled flow of either ethanol or isopropyl alcohol (IPA) vapour. In spite of the small magnitude of the effect, the results show a selective vapour response (depending on the materials used).

  20. GISAXS/GIXRD View of ZnO Films with Hierarchical Structural Elements

    Directory of Open Access Journals (Sweden)

    M. Lučić Lavčević

    2012-01-01

    Full Text Available ZnO films constituted of porous sheet-like structures, formed by calcination of precursor, were examined using scanning electron microscopy and simultaneous small-angle scattering and diffraction of the synchrotron-sourced X-rays, under the grazing-incidence conditions. The presented analysis enabled insight into the complexity of the film morphology, which revealed substrate sensitivity on the microscopic and nanoscopic length scales. The average size and spatial arrangement of nanoparticles, single-crystal domains, and the average size and features of nanopores in sheet-like structures were determined for films deposited on glass, polycrystalline ZnO layer, and silicon.